Article

Cutaneous Leishmaniasis Induces a Transmissible Dysbiotic Skin Microbiota that Promotes Skin Inflammation

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Skin microbiota can impact allergic and autoimmune responses, wound healing, and anti-microbial defense. We investigated the role of skin microbiota in cutaneous leishmaniasis and found that human patients infected with Leishmania braziliensis develop dysbiotic skin microbiota, characterized by increases in the abundance of Staphylococcus and/or Streptococcus. Mice infected with L. major exhibit similar changes depending upon disease severity. Importantly, this dysbiosis is not limited to the lesion site, but is transmissible to normal skin distant from the infection site and to skin from co-housed naive mice. This observation allowed us to test whether a pre-existing dysbiotic skin microbiota influences disease, and we found that challenging dysbiotic naive mice with L. major or testing for contact hypersensitivity results in exacerbated skin inflammatory responses. These findings demonstrate that a dysbiotic skin microbiota is not only a consequence of tissue stress, but also enhances inflammation, which has implications for many inflammatory cutaneous diseases.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... In addition to commensal bacteria on the host's skin, recent data show the infection site is also exposed to microbes from the sand fly gut [12]. Ulcerated lesions provide a portal for bacterial invasion, occasionally leading to superinfection [13][14][15]. Staphylococcus and Streptococcus species are the two most common bacterial genera that have been detected in surveys of CL lesion microbiota [13][14][15]. Sand fly midgut microbiota include bacterial species belonging to the families Staphylococcaceae and Streptococcaceae within the phylum Firmicutes [16,17]. ...
... Ulcerated lesions provide a portal for bacterial invasion, occasionally leading to superinfection [13][14][15]. Staphylococcus and Streptococcus species are the two most common bacterial genera that have been detected in surveys of CL lesion microbiota [13][14][15]. Sand fly midgut microbiota include bacterial species belonging to the families Staphylococcaceae and Streptococcaceae within the phylum Firmicutes [16,17]. ...
... This led us to use a murine model of CL to examine the phenotypic effects of bacteria introduced at different times or body site locations relative to the L. major parasitic infection. We chose to use S. aureus, a bacterium found in the sand fly gut [16] and commonly present at the site of human CL lesions [13][14][15], at a subclinical 10 4 bacterial colony-forming units (CFUs) dose, which results in detectable but minimal swelling, and no ulceration in murine skin (S1 Fig). The simultaneous administration of L. major and S. aureus (L+S in figures) at a single site led to a significant and pronounced exacerbation of pathology compared to mice infected with either L. major or S. aureus alone (Lm or Sa in figures) (Fig 1). ...
Article
Full-text available
Cutaneous leishmaniasis (CL) is a parasitic disease causing chronic, ulcerating skin lesions. Most humans infected with the causative Leishmania protozoa are asymptomatic. Leishmania spp. are usually introduced by sand flies into the dermis of mammalian hosts in the presence of bacteria from either the host skin, sand fly gut or both. We hypothesized that bacteria at the dermal inoculation site of Leishmania major will influence the severity of infection that ensues. A C57BL/6 mouse ear model of single or coinfection with Leishmania major, Staphylococcus aureus, or both showed that single pathogen infections caused localized lesions that peaked after 2–3 days for S. aureus and 3 weeks for L. major infection, but that coinfection produced lesions that were two-fold larger than single infection throughout 4 weeks after coinfection. Coinfection increased S. aureus burdens over 7 days, whereas L. major burdens (3, 7, 28 days) were the same in singly and coinfected ears. Inflammatory lesions throughout the first 4 weeks of coinfection had more neutrophils than did singly infected lesions, and the recruited neutrophils from early (day 1) lesions had similar phagocytic and NADPH oxidase capacities. However, most neutrophils were apoptotic, and transcription of immunomodulatory genes that promote efferocytosis was not upregulated, suggesting that the increased numbers of neutrophils may, in part, reflect defective clearance and resolution of the inflammatory response. In addition, the presence of more IL-17A-producing γδ and non-γδ T cells in early lesions (1–7 days), and L. major antigen-responsive Th17 cells after 28 days of coinfection, with a corresponding increase in IL-1β, may recruit more naïve neutrophils into the inflammatory site. Neutralization studies suggest that IL-17A contributed to an enhanced inflammatory response, whereas IL-1β has an important role in controlling bacterial replication. Taken together, these data suggest that coinfection of L. major infection with S. aureus exacerbates disease, both by promoting more inflammation and neutrophil recruitment and by increasing neutrophil apoptosis and delaying resolution of the inflammatory response. These data illustrate the profound impact that coinfecting microorganisms can exert on inflammatory lesion pathology and host adaptive immune responses.
... The diverse pathologies associated with Leishmania infections develop following excessive inflammatory responses by the infected tissues due to dis-regulated immune responses, which are increasingly appreciated to be triggered by complex network of interactions between the parasites, host immunocytes, the bacteria from the human skin microbiota and sandfly vector gut microbiota in addition to Leishmania RNA viruses (LRV) known to infect some Leishmania species (Ives et al., 2011;Brodskyn and de Oliveira, 2012;Gimblet et al., 2017;Cruz and Freitas-Castro, 2019) (Figure 2). Understanding the complex interplay between these factors involved in the host-parasitemicrobiota interactions during Leishmania infection is crucial to refine the design of in vivo and in vitro Leishmania infection models and assays to study the biology of these parasites in more details and to eventually develop more effective prophylactic and therapeutic strategies with minimal or no side effects (Figure 2). ...
... Moreover, a detailed metatranscriptomics analysis in situ in the skin and in the insect vector covering the insect gut microbiota and the human skin microbiota, respectively, could aid in enriching our understanding of the factors that govern the complex host-parasite-microbiota interplay and their potential impact and relationship with the different forms of leishmaniasis, CL, VL, and MCL. Skin microbiota dysbiosis associated with CL requires further attention modulating the pathobiology of Leishmania infections and appears, importantly, as a potential novel therapeutic target (Gimblet et al., 2017). Notably, the mammalian skin and insect gut microbiota are also potentially relevant to trigger and modulate the shift from CL to VL (Gimblet et al., 2017). ...
... Skin microbiota dysbiosis associated with CL requires further attention modulating the pathobiology of Leishmania infections and appears, importantly, as a potential novel therapeutic target (Gimblet et al., 2017). Notably, the mammalian skin and insect gut microbiota are also potentially relevant to trigger and modulate the shift from CL to VL (Gimblet et al., 2017). Moreover, the impact of LRV and other viruses, such as the Lymphocytic choriomeningitis virus (LCMV), on the pathobiology of various Leishmania species would also be of great interest to investigate with more integrative approaches and model systems (Ives et al., 2011;Crosby et al., 2015). ...
Article
Full-text available
Leishmaniasis is a vector-borne disease caused by a protozoa parasite from over 20 Leishmania species. The clinical manifestations and the outcome of the disease vary greatly. Global RNA sequencing (RNA-Seq) analyses emerged as a powerful technique to profile the changes in the transcriptome that occur in the Leishmania parasites and their infected host cells as the parasites progresses through their life cycle. Following the bite of a sandfly vector, Leishmania are transmitted to a mammalian host where neutrophils and macrophages are key cells mediating the interactions with the parasites and result in either the elimination the infection or contributing to its proliferation. This review focuses on RNA-Seq based transcriptomics analyses and summarizes the main findings derived from this technology. In doing so, we will highlight caveats in our understanding of the parasite's pathobiology and suggest novel directions for research, including integrating more recent data highlighting the role of the bacterial members of the sandfly gut microbiota and the mammalian host skin microbiota in their potential role in influencing the quantitative and qualitative aspects of leishmaniasis pathology.
... In late phases of CL, granulomatous inflammatory reactions can been seen in lesions caused by Leishmania species such as L. tropica, L. braziliensis, L. mexicana and L. panamensis [48,52]. However, in the initial and intermediate phases of CL, the skin damage allows bacteria to penetrate the epidermal barrier and subsequently colonize the tissue [53] (Figure 1A & B). Some authors suggest that patients with ulcerated skin lesions are subject to secondary infection, more than patients with non-ulcerated skin lesions [54][55][56]. ...
... In fact, injuries disrupt the tissue homeostasis altering the oxygen level of skin layers of various depths and less oxygen is available in deeper microenvironments [54,65]. Gimblet et al. [53] also studied the skin of CL patients caused by L. braziliensis showing a Table 1. Diversity of secondary bacteria related to infection with Leishmania spp., found in lesions of human patients with CL or VL. ...
... Bacterioides sp. ‡ § [53,86] Beta hemolytic Streptococcus ‡ [70,124,127] Bifidobacterium sp. § [86] Class Bacilli ‡ ...
Article
Leishmaniasis is a zoonotic and neglected disease, which represents an important public health problem worldwide. Different species of Leishmania are associated with different manifestations, and a practical problem that can worsen the condition of hosts infected with Leishmania is the secondary infection caused by bacteria. This review aims to examine the importance and prevalence of bacteria co-infection during leishmaniasis and the nature of this ecological relationship. In the cases discussed in this review, the facilitation phenomenon, defined as any interaction where the action of one organism has a beneficial effect on an organism of another species, was considered in the Leishmania–bacteria interaction, as well as the effects on one another and their consequences for the host.
... braziliensis patients with classical cutaneous leishmanaisis mostly control the parasites, they develop chronic lesions that can be difficult to treat [2][3][4]. Several studies indicate that the magnitude of disease is often due to an uncontrolled inflammatory response, which can be mediated by IL-17A and/or IL-1b [1,[5][6][7][8][9][10][11]. Using a combination of murine models and human studies we and others have shown that the skin microbiome enhances IL-1b and IL-17A production and contributes to increased pathology in cutaneous leishmaniasis [10,12,13]. ...
... Several studies indicate that the magnitude of disease is often due to an uncontrolled inflammatory response, which can be mediated by IL-17A and/or IL-1b [1,[5][6][7][8][9][10][11]. Using a combination of murine models and human studies we and others have shown that the skin microbiome enhances IL-1b and IL-17A production and contributes to increased pathology in cutaneous leishmaniasis [10,12,13]. However, while the role of T cells in promoting an increased inflammatory response is well established [1], whether innate cells initiate and/or amplify a pathogenic response in leishmaniasis is unknown. ...
... Recent studies suggest that alterations to the skin microbiota, particularly changes in the dominance of Staphylococcus and Streptococcus species, at the site of Leishmania infection are linked to disease outcome [10]. Infection-induced alterations in the skin microbiota of L. major infected mice are linked to disease severity and immune-mediated inflammatory responses [10,22]. ...
Preprint
Full-text available
p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Helvetica} span.s1 {color: #222222} span.s2 {font: 8.0px Helvetica} Innate lymphoid cells (ILCs) comprise a heterogeneous population of immune cells that maintain barrier function and can initiate a protective or pathological immune response upon infection. Here we show the involvement of IL-17A-producing ILCs in microbiota-driven immunopathology in cutaneous leishmaniasis. IL-17A-producing ILCs were RORgt + and were enriched in Leishmania major infected skin, and topical colonization with Staphylococcus epidermidis before L. major infection exacerbated the skin inflammatory responses and IL-17A-producing RORgt + ILC accumulation without impacting type 1 immune responses. IL-17A responses in ILCs were directed by Batf3 dependent CD103 + dendritic cells, and experiments using ILC deficient Rag1 -/- mice established that IL-17A + ILCs were sufficient in driving the inflammatory responses. As depletion of ILCs or neutralization of IL-17A diminished the microbiota mediated immunopathology. Taken together, this study indicates that the skin microbiota promotes RORgt + IL-17A-producing ILCs, which augment the skin inflammation in cutaneous leishmaniasis.
... For example, even though L. braziliensis patients with classical cutaneous leishmanaisis mostly control the parasites, they develop chronic lesions that can be difficult to treat [2,3]. Several studies indicate that the magnitude of disease is often due to an uncontrolled inflammatory response, which can be mediated by IL-17A and/or IL-1β [1][2][3][4][5][6][7][8][9][10]. Using a combination of murine models and human studies we and others have shown that the skin microbiome enhances IL-1β and IL-17A production and contributes to increased pathology in cutaneous leishmaniasis [9,11,12]. ...
... Several studies indicate that the magnitude of disease is often due to an uncontrolled inflammatory response, which can be mediated by IL-17A and/or IL-1β [1][2][3][4][5][6][7][8][9][10]. Using a combination of murine models and human studies we and others have shown that the skin microbiome enhances IL-1β and IL-17A production and contributes to increased pathology in cutaneous leishmaniasis [9,11,12]. However, while the role of T cells in promoting an increased inflammatory response is well established [1], whether innate cells initiate and/or amplify a pathogenic response in leishmaniasis is unknown. ...
... Recent studies suggest that alterations to the skin microbiota, particularly changes in the dominance of Staphylococcus and Streptococcus species, at the site of Leishmania infection are linked to disease outcome [9]. Infection-induced alterations in the skin microbiota of L. major infected mice are linked to disease severity and immune-mediated inflammatory responses [9,20]. ...
Article
Full-text available
Innate lymphoid cells (ILCs) comprise a heterogeneous population of immune cells that maintain barrier function and can initiate a protective or pathological immune response upon infection. Here we show the involvement of IL-17A-producing ILCs in microbiota-driven immunopathology in cutaneous leishmaniasis. IL-17A-producing ILCs were RORγt ⁺ and were enriched in Leishmania major infected skin, and topical colonization with Staphylococcus epidermidis before L . major infection exacerbated the skin inflammatory responses and IL-17A-producing RORγt ⁺ ILC accumulation without impacting type 1 immune responses. IL-17A responses in ILCs were directed by Batf3 dependent CD103 ⁺ dendritic cells and IL-23. Moreover, experiments using Rag1 -/- mice established that IL-17A ⁺ ILCs were sufficient in driving the inflammatory responses as depletion of ILCs or neutralization of IL-17A diminished the microbiota mediated immunopathology. Taken together, this study indicates that the skin microbiota promotes RORγt ⁺ IL-17A-producing ILCs, which augment the skin inflammation in cutaneous leishmaniasis.
... A diverse skin microbiome is hypothesized to promote health by preventing invading microorganisms from causing infection directly or by educating T cells in the skin to respond to specific microorganisms (19). In contrast, the diversity of the skin microbiome can be reduced during cutaneous infections, reflecting overgrowth of specific pathogens or opportunistic commensals, and possibly microorganisms that are more resistant to the host immune responses (12,22,23). Our observed alpha and beta diversity measurements for AC and CU samples are similar to previous studies that have compared microbiomes of healthy and diseased skin (12,22,23). ...
... In contrast, the diversity of the skin microbiome can be reduced during cutaneous infections, reflecting overgrowth of specific pathogens or opportunistic commensals, and possibly microorganisms that are more resistant to the host immune responses (12,22,23). Our observed alpha and beta diversity measurements for AC and CU samples are similar to previous studies that have compared microbiomes of healthy and diseased skin (12,22,23). ...
Article
Full-text available
Cutaneous ulcers (CU) affect approximately 100,000 children in the tropics each year. While two-thirds of CU are caused by Treponema pallidumpertenueHaemophilus ducreyi
... Overall, these studies highlight the complexity of immune events following transmission that transcend a Th1 versus a Th2 phenotype. Another facet to inflammation and its role in leishmaniasis pathology is the observation that infection with L. major induces dysbiosis in skin-residing host microbiota that is not limited to lesions but extends to distal sites and other co-housed mice [76]. Importantly, skin dysbiosis exacerbated CL pathology without an effect on parasites due to an aggravated inflammatory response [76]. ...
... Another facet to inflammation and its role in leishmaniasis pathology is the observation that infection with L. major induces dysbiosis in skin-residing host microbiota that is not limited to lesions but extends to distal sites and other co-housed mice [76]. Importantly, skin dysbiosis exacerbated CL pathology without an effect on parasites due to an aggravated inflammatory response [76]. This study further emphasizes the complexity of the inflammatory milieu in the skin of infected individuals that is distinct from normal skin and may impact vector transmission or pick-up of parasites by sand flies. ...
Article
Full-text available
The contribution of vector transmission to pathogen establishment is largely underrated. For Leishmania, transmission by sand flies is critical to early survival involving an irreproducible myriad of parasite, vector, and host molecules acting in concert to promote infection at the bite site. Here, we review recent breakthroughs that provide consequential insights into how vector transmission of Leishmania unfolds. We focus on recent work pertaining to the effect of gut microbiota, sand fly immunity, and changes in metacyclogenesis upon multiple blood meals, on Leishmania development and transmission. We also explore how sand fly saliva, egested parasite molecules and vector gut microbiota, and bleeding have been implicated in modulating the early innate host response to Leishmania, affecting the phenotype of neutrophils and monocytes arriving at the bite site.
... Several studies focused on the use of HA-based liposomes or HA-based lipid nanocarriers for therapeutics in cancer and inflammation [28][29][30][31]. The inflammation is directly related to cutaneous leishmaniasis, which is not only caused by uncontrolled parasite replication, but also by an immune response linked to the inflammatory process [32]. The publications describe that the over-expression of macrophage-surface antigens, as the CD44, is associated with inflammation, and the HA can specifically bound on the activated macrophages in the inflamed tissues. ...
... The selective accumulation of liposomes in the paw can be attributed to the elimination by local macrophages, whereas inflammation in the periphery of the skin lesions increased vascular permeability and allowed the local leakage of intravenously administered liposomes [24]. Indeed, the factors responsible for disease in cutaneous leishmaniasis are not caused only by uncontrolled parasite replication, but also by an exaggerated immune response leading to excessive inflammation [32]. Experimental models of mice paw infection with L. amazonensis showed an induction of a strong inflammatory response in the skin, forming paw edema by recruiting macrophages to inflamed paw tissue [67,68]. ...
Article
The use of nanocarriers for drug delivery is a strategy aimed to improve therapeutic indices through changes in their pharmacokinetic and pharmacodynamic characteristics. Liposomes are well-investigated nanocarriers for drug delivery to macrophage-targeted therapy, the main hosts of intracellular pathogens of some infectious diseases, such as leishmaniasis. In this study, we developed hyaluronic acid (HA)-coated liposomes by different methods that can encapsulate a new quinoxaline derivative, the LSPN331, to increase its solubility and improve its bioavailability. The surface modification of liposomes and their physicochemical characteristics may depend on the coating method, which may be a critical parameter with regard to the route of administration of the antileishmanial drug. Liposomes with identical phospholipid composition containing the same drug were developed, and different biological responses were verified, and our hypothesis is that it is related to the type of modification of the surface. Different physicochemical characterization techniques (dynamic light scattering, transmission electron microscopy and UV–vis quantification of labeled-HA) were used to confirm the successful modification of liposomes as well as their stability upon storage. The encapsulation of LSPN331 was performed using HPLC method, and the entrapment efficiency (EE%) was satisfatory in all formulations, considering results of similar formulations in the literature. Furthermore, in vitro and in vivo studies were carried out to evaluate the efficacy against the parasite Leishmania amazonensis. The in vitro activity was maintained or even improved and HA-coated liposomes showed the ability to target to the site of action by the proposed routes of administration, topically and intravenously. Both formulations are promising for future tests of antileishmania activity in vivo.
... Also, skin microbiome dysbiosis has been associated with infections caused by eukaryotic parasites, such as human itch mite (Sarcoptes scabiei var. hominis; Bhat et al., 2017), and Leishmania species (Gimblet et al., 2017). Gimblet et al., 2017 The interactions related to skin microbiomes, including environmental exposures and the host immune system, strongly influence the host's overall health (Prescott et al., 2017). ...
... hominis; Bhat et al., 2017), and Leishmania species (Gimblet et al., 2017). Gimblet et al., 2017 The interactions related to skin microbiomes, including environmental exposures and the host immune system, strongly influence the host's overall health (Prescott et al., 2017). ...
Article
Skin is a complex organ serving a critical role as a barrier and mediator of interactions between the human body and its environment. Recent studies have uncovered how resident microbial communities play a significant role in maintaining the normal healthy function of the skin and the immune system. In turn, numerous host‐associated and environmental factors influence these communities' composition and diversity across the cutaneous surface. In addition, specific compositional changes in skin microbiota have also been connected to the development of several chronic diseases. The current era of microbiome research is characterized by its reliance on large data sets of nucleotide sequences produced with high‐throughput sequencing of sample‐extracted DNA. These approaches have yielded new insights into many previously uncharacterized microbial communities. Application of standardized practices in the study of skin microbial communities could help us understand their complex structures, functional capacities, and health associations and increase the reproducibility of the research. Here, we overview the current research in human skin microbiomes and outline challenges specific to their study. Furthermore, we provide perspectives on recent advances in methods, analytical tools, and applications of skin microbiomes in medicine and forensics. This article is protected by copyright. All rights reserved.
... There is therefore still a strong need to understand the role of lesion-free tissues in the transmission of Leishmania and in disease pathogenesis. However, our results are consistent with findings of microbiota dysbiosis in lesion-adjacent tissues in humans and in lesion-free cutaneous sites in mice [39]. ...
Article
Full-text available
Cutaneous leishmaniasis (CL) is the most common disease form caused by a Leishmania parasite infection and considered a neglected tropical disease (NTD), affecting 700,000 to 1.2 million new cases per year in the world. Leishmania major is one of several different species of the Leishmania genus that can cause CL. Current CL treatments are limited by adverse effects and rising resistance. Studying disease metabolism at the site of infection can provide knowledge of new targets for host-targeted drug development. In this study, tissue samples were collected from mice infected in the ear or footpad with L. major and analyzed by untargeted liquid chromatography-tandem mass spectrometry (LC-MS/MS). Significant differences in overall metabolite profiles were noted in the ear at the site of the lesion. Interestingly, lesion-adjacent, macroscopically healthy sites also showed alterations in specific metabolites, including selected glycerophosphocholines (PCs). Host-derived PCs in the lower m/z range (m/z 200–799) showed an increase with infection in the ear at the lesion site, while those in the higher m/z range (m/z 800–899) were decreased with infection at the lesion site. Overall, our results expanded our understanding of the mechanisms of CL pathogenesis through host metabolism and may lead to new curative measures against infection with Leishmania.
... However, environmental exposure and poor hygiene at the lesion site may promote polymicrobial infections (Salgado, Queiroz et al., 2016). Moreover, Leishmania parasites normally disrupt the natural skin barrier to establish cutaneous lesions that predispose to bacterial infections and can further cause dysbiosis by changing the composition of skin microbiota (Gimblet, Meisel et al., 2017;Silva-Almeida, Pereira et al., 2012). Secondary bacterial infections are frequently observed in 22% to 68% of the CL patients (Fontes, Carvalho et al., 2005;Vera, Macedo et al., 2006). ...
Article
Full-text available
A B S T R A C T The human skin microbiome is a major source of bacteria in cutaneous leishmaniasis (CL) ulcers following the fall of the crust and the subsequent formation of a shallow depression in the epidermis and dermis of the skin. As a result, secondary bacterial infections are frequently observed which impair the healing process. Our study aimed to investigate the bacterial communities in CL lesions using next-generation sequencing. A total of 298 patients (178 males and 120 females; the median age of 17) presenting ulcerated skin lesions suspected with CL were included in this study. CL was confirmed in 153 (51%) cases by ITS1-PCR and/ or microscopy. Based on bacterial 16S rRNA-PCR, 92 samples were positive for the presence of bacteria, while 206 samples were negative and excluded from the microbiome study. A total of 925 Operational Taxonomic Units (OTUs) were identified and assigned to 215 genera. Despite an insignificant difference in the microbiome composition between CL and non-CL lesions, the phylum level analysis revealed that Actinobacteria was significantly higher in CL ulcers while Proteobacteria was significantly higher in non-CL ulcers (X2, P=0.039). The relative abundance of the most commonly encountered skin pathogens i. e E. coli, Pseudomonas aeraginosa, Enterobacter, Enterococcus and Acinetobacter species were significantly higher in non-CL ulcers (X2, P<0.05) compared to Staphylococcus aureus and Proteus mirabilis which was higher in CL ulcers (P<0.05). Our data showed that bacterial communities did not cluster according to the Leishmania infection. Nonetheless, bacterial diversity was lower in CL compared to non-CL lesions. The presence of pathogenic bacteria in CL lesions such as S. aureus might exacerbate lesions, hinder diagnosis, and delay healing.
... However, environmental exposure and poor hygiene at the lesion site may promote polymicrobial infections (Salgado, Queiroz et al., 2016). Moreover, Leishmania parasites normally disrupt the natural skin barrier to establish cutaneous lesions that predispose to bacterial infections and can further cause dysbiosis by changing the composition of skin microbiota (Gimblet, Meisel et al., 2017;Silva-Almeida, Pereira et al., 2012). Secondary bacterial infections are frequently observed in 22% to 68% of the CL patients (Fontes, Carvalho et al., 2005;Vera, Macedo et al., 2006). ...
Article
The human skin microbiome is a major source of bacteria in cutaneous leishmaniasis (CL) ulcers following the fall of the crust and the subsequent formation of a shallow depression in the epidermis and dermis of the skin. As a result, secondary bacterial infections are frequently observed which impair the healing process. Our study aimed at studying the bacterial communities in CL lesions using next-generation sequencing. A total of 298 patients (178 males and 120 females; median age of 17) presenting ulcerated skin lesions suspected with CL were included in this study. CL was confirmed in 153 (51%) cases by ITS1-PCR and/ or microscopy. Based on bacterial 16S rRNA-PCR, 92 samples were positive for the presence of bacteria, while 206 samples were negative and excluded from the microbiome study. A total of 925 Operational Taxonomic Units (OTUs) were identified and assigned to 215 genera. Despite insignificant difference in the microbiome composition between CL and non-CL lesions, the phylum level analysis revealed that Actinobacteria was significantly higher in CL ulcers while Protoeobacteria was significantly higher in non-CL ulcers (X2, P=0.039). The relative abundance of the most commonly encountered skin pathogens i. e E coli, Pseudomonas aeruginosa, Enterobacter, Enterococcus and Acinetobacter species were significantly higher in non-CL ulcers (X2, P<0.05) compared to Staphylococcus aureus and Proteus mirabilis which were higher in CL ulcers (P<0.05). Our data showed that bacterial communities did not cluster according to the Leishmania infection. Nonetheless, bacterial diversity was lower in CL compared to non-CL lesions. Presence of pathogenic bacteria in CL lesions such as S. aureus might exacerbate lesions, hinder diagnosis, and delay healing.
... Differences in cell types, metabolism, oxygen levels, and temperature can influence the outcome of cutaneous leishmaniasis, but have been little studied in this disease. Further, the skin directly interacts with the external environment and the skin microbiome can have significant effects on the outcome of infection (76,77). It is fair to say that the success of host-directed therapies for cutaneous leishmaniasis will depend upon a better understanding of the skin, and for leishmaniasis we have just "scratched the surface" in that arena. ...
Article
Full-text available
Cutaneous leishmaniasis exhibits a wide spectrum of clinical presentations from self-resolving infections to severe chronic disease. Anti-parasitic drugs are often ineffective in the most severe forms of the disease, and in some cases the magnitude of the disease can result from an uncontrolled inflammatory response rather than unrestrained parasite replication. In these patients, host-directed therapies offer a novel approach to improve clinical outcome. Importantly, there are many anti-inflammatory drugs with known safety and efficacy profiles that are currently used for other inflammatory diseases and are readily available to be used for leishmaniasis. However, since leishmaniasis consists of a wide range of clinical entities, mediated by a diverse group of leishmanial species, host-directed therapies will need to be tailored for specific types of leishmaniasis. There is now substantial evidence that host-directed therapies are likely to be beneficial beyond autoimmune diseases and cancer and thus should be an important component in the armamentarium to modulate the severity of cutaneous leishmaniasis.
... Exposure of a host to an infectious pathogen can represent a disturbance to the microbiome [16][17][18]. However, little is known about the resilience (recovery) of nonhuman animal microbiomes following disturbance by infectious disease. ...
Article
Full-text available
Infectious pathogens can disrupt the microbiome in addition to directly affecting the host. Impacts of disease may be dependent on the ability of the microbiome to recover from such disturbance, yet remarkably little is known about microbiome recovery after disease, particularly in nonhuman animals. We assessed the resilience of the amphibian skin microbial community after disturbance by the pathogen, Batrachochytrium dendrobatidis (Bd). Skin microbial communities of laboratory-reared mountain yellow-legged frogs were tracked through three experimental phases: prior to Bd infection, after Bd infection (disturbance), and after clearing Bd infection (recovery period). Bd infection disturbed microbiome composition and altered the relative abundances of several dominant bacterial taxa. After Bd infection, frogs were treated with an antifungal drug that cleared Bd infection, but this did not lead to recovery of microbiome composition (measured as Unifrac distance) or relative abundances of dominant bacterial groups. These results indicate that Bd infection can lead to an alternate stable state in the microbiome of sensitive amphibians, or that microbiome recovery is extremely slow—in either case resilience is low. Furthermore, antifungal treatment and clearance of Bd infection had the additional effect of reducing microbial community variability, which we hypothesize results from similarity across frogs in the taxa that colonize community vacancies resulting from the removal of Bd. Our results indicate that the skin microbiota of mountain yellow-legged frogs has low resilience following Bd-induced disturbance and is further altered by the process of clearing Bd infection, which may have implications for the conservation of this endangered amphibian.
... Studies in recent decades have found that inflammation was associated with microbiota and skin microbiota was reported to influence skin wound healing [41]. Following skin injury, skin-resident microbiota and AGING pathogenic species may colonize the wound and proliferate. ...
Article
The mushroom Ganoderma lucidum (G. lucidum Leyss. ex Fr.) Karst has been a traditional Chinese medicine for millennia. In this study, we isolated the Ganoderma lucidum spore oil (GLSO) and evaluated the effect of GLSO on skin burn wound healing and the underlying mechanisms. Mice were used to perform skin wound healing assay. Wound analysis was performed by photography, hematoxylin/eosin staining, Masson's Trichrome staining and immunohistochemical analysis. Microbiota on the wounds were analyzed using the 16s rRNA sequence and quantitative statistics. The lipopolysaccharide (LPS) content was examined in skin wounds and serum using an enzyme-linked immunosorbent assay (ELISA). The expression of Toll-like receptor 4 (TLR4) and the relative levels of inflammatory cytokines were determined by qPCR and immunofluorescence assay. A pseudo-germfree mouse model treated with antibiotics was used to investigate whether GLSO accelerated skin burn wound healing through the skin microbiota. We found that GLSO significantly accelerated the process of skin wound healing and regulated the levels of gram-negative and gram-positive bacteria. Furthermore, GLSO reduced LPS and TLR4, and levels of some other related inflammatory cytokines. The assay with the pseudo-germfree mice model showed that GLSO had a significant acceleration on skin wound healing in comparison with antibiotic treatment. Thus, GLSO downregulated the inflammation by regulating skin microbiota to accelerate skin wound healing. These findings provide a scientific rationale for the potential therapeutic use of GLSO in skin burn injury.
... While the microbiome is increasingly recognized as a key determinant of gut health and human development, the impact of naturally acquired parasite infections on the microbial community in the gut is poorly understood. Many studies of parasites and their impact on the microbiome involve experimental infections of laboratory animals (10)(11)(12)(13)(14)(15). While such studies can be powerful for elucidating mechanisms, they often involve laboratory-adapted parasite strains, specialized animal husbandry practices, or high infectious doses, all of which can impact host immunity and the composition of the microbiome. ...
Article
Full-text available
Enteric parasitic infections are among the most prevalent infections in lower- and middle-income countries (LMICs) and have a profound impact on global public health. While the microbiome is increasingly recognized as a key determinant of gut health and human development, the impact of naturally acquired parasite infections on microbial community structure in the gut, and the extent to which parasite-induced changes in the microbiome may contribute to gastrointestinal symptoms, is poorly understood. Enteric parasites are routinely identified in companion animals in the United States, presenting a unique opportunity to leverage this animal model to investigate the impact of naturally acquired parasite infections on the microbiome. Clinical, parasitological, and microbiome profiling of a cohort of 258 dogs revealed a significant correlation between parasite infection and composition of the bacterial community in the gut. Relative to other enteric parasites, Giardia was associated with a more pronounced perturbation of the microbiome. To compare our findings to large-scale epidemiological studies of enteric diseases in humans, a database mining approach was employed to integrate clinical and micro- biome data. Substantial and consistent alterations to microbiome structure were observed in Giardia-infected children. Importantly, infection was associated with a reduction in the relative abundance of potential pathobionts, including Gammapro- teobacteria, and an increase in Prevotella—a profile often associated with gut health. Taken together, these data show that widespread Giardia infection in young animals and humans is associated with significant remodeling of the gut microbiome and provide a possible explanation for the high prevalence of asymptomatic Giardia infections observed across host species. © 2020 Berry et al. This is an openaccess article distributed under the terms of the Creative Commons Attribution 4.0 International license.
... CL is transmitted by the female sand-fly and presents on the skin as an erythematous papule that develops into an ulcer with a raised and distinct border (Markle and Makhoul 2004). In mice this disease induces dysbiosis within the skin microbiota (a surge in abundance of Staphylococcus and Streptococcus species) resulting in inflammation (Gimblet et al. 2017). Amphotericin B, an antibiotic originally isolated from Streptomyces nodosus, is a powerful antifungal agent and was found to have a positive effect at eliminating these ulcers (Mushtaq, Dogra and Dogra 2016). ...
Article
Full-text available
Interest surrounding the role that skin microbes play in various aspects of human health has recently experienced a timely surge, particularly among researchers, clinicians, and consumer-focused industries. The world is now approaching a post-antibiotic era where conventional antibacterial therapeutics have shown a loss in effectiveness due to overuse, leading to the looming antibiotic resistance crisis. The increasing threat posed by antibiotic resistance is compounded by an inadequate discovery rate of new antibiotics and has, in turn, resulted in global interest for alternative solutions. Recent studies have demonstrated that imbalances in skin microbiota are associated with assorted skin diseases and infections. Specifically, restoration of this ecosystem imbalance results in an alleviation of symptoms, achieved simply by applying bacteria normally found in abundance on healthy skin to the skin of those deficient in beneficial bacteria. The aim of this review is to discuss the currently available literature on biological tools that have the potential to manipulate the skin microbiota, with particular focus on bacteriocins, phage therapy, antibiotics, probiotics, and targets of the gut-skin axis. This review will also address how the skin microbiota protects humans from invading pathogens in the external environment while discussing novel strategies to manipulate the skin microbiota to avoid and/or treat various disease states.
... Although the majority of the microbiota resides in the gut, there are large populations that also reside in the mouth, urinary tract and on the skin. [5][6][7] Most principles learned from the study of gut microbiome apply to microbial habitats throughout the body. The study of microbiota-virus-host interactions in each specific location of the body allows the understanding of localized immunity and susceptibility to invading viruses and how the local microbiota factor into these processes. ...
The influence of the microbiota on viral infection susceptibility and disease outcome is undisputable although varies among viruses. The purpose of understanding the interactions between microbiota, virus, and host is to identify practical, effective, and safe approaches that target microbiota for the prevention and treatment of viral diseases in humans and animals, as currently there are few effective and reliable antiviral therapies available. The initial step for achieving this goal is to gather clinical evidences, focusing on the viral pathogens—from human and animal studies—that have already been shown to interact with microbiota. The subsequent step is to identify mechanisms, through experimental evidences, to support the development of translational applications that target microbiota. In this chapter, we review evidences of virus infections altering microbiota and of microbiota enhancing or suppressing infectivity, altering host susceptibility to certain viral diseases, and influencing vaccine immunogenicity in humans and farm animals.
... However, how dysbiosis of the skin microbiome relates to tropical diseases that affect skin integrity is understudied. For example, there are only a few studies to date that report dysbiosis in the skin of patients with leprosy (8,9) or leishmaniasis (10). Whether other skin-affecting tropical diseases or neglected infectious diseases (e.g., tuberculosis, filariasis, schistosomiasis), as well as the infection of human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) that may alter the skin immune system, could interact with the dysbiosis of the skin microbiota remains unclear. ...
Article
Full-text available
Characterization of microbial communities in the skin in healthy individuals and diseased patients holds valuable information for understanding pathogenesis of skin diseases and as a source for developing novel therapies. Notably, resources regarding skin microbiome are limited in developing countries where skin disorders from infectious diseases are extremely common. A simple method for sample collection and processing for skin microbiome studies in such countries is crucial. The aim of this study is to confirm the feasibility of collecting skin microbiota from individuals in Yaoundé, a capital city of Cameroon, and subsequent extraction of bacterial DNA in a resource limited setting. Skin swabs from several individuals in Yaoundé were successfully obtained, and sufficient amount of bacterial 16S ribosomal RNA-coding DNA was collected, which was confirmed by quantitative PCR. The median copy number of 16S ribosomal RNA gene varied across participants and collection sites, with significantly more copies in samples collected from the forehead compared to the left and right forearm, or back. This study demonstrated that collecting surface skin microbes using our swabbing method is feasible in a developing country. We further showed that even with limited resources, we could collect sufficient amount of skin microbiota from the inhabitants in Yaoundé where no studies of skin microbiome were reported, which can be passed to further metagenomic analysis such as next generation sequencing.
... For the most part, microbiome studies on obesity have been limited to the gut microbiome. Furthermore, skin microbiome studies have overwhelmingly focused on the structure of the healthy skin microbiome [12,13], its temporal stability [12,[14][15][16], or the skin microbiome of dermatological conditions [17][18][19][20][21][22]. Recently, Moestrup et al. examined the skin microbiome of mice maintained on a high-fat diet compared to those on a caloric-neutral (normal) diet. ...
Article
Full-text available
Microbiome compositional changes are associated with obesity in the gut. Emerging evidence points to a connection between gut and skin microbial communities. We hypothesized that skin microbiome compositional changes are associated with different BMI levels and that overweight or obese individuals would have reduced skin microbial diversity. We statistically analyzed gut, oral and skin microbiome samples to recapture previously observed partitioning between the microbiomes of these sites. We further analyzed 822 skin microbiome samples from the American Gut Project database and correlated BMI levels with community structure and composition using QIIME. Gut, oral and skin samples showed distinct community composition, and gut and skin microbial diversity was affected by BMI. Oral microbial diversity was not affected by BMI. Skin beta-diversity and community composition was correlated with BMI category, and Corynebacterium relative abundance was significantly correlated with BMI. In conclusion, non-cutaneous conditions affect the composition of the skin microbiome and the skin microbiome may therefore be used as a biomarker for disease manifestations beyond those with a cutaneous etiology. Keywords: Skin microbiome, BMI, Obesity, Human microbiome, American Gut Project
... Emerging data suggest that the human body is inhabited by a wide range of microorganisms that are collectively referred to as the commensal microbiota. A majority of the microbiota reside in the intestine, while distinct populations can also be found on the surfaces of the mouth, skin, and urinary tract (1)(2)(3). A wealth of evidence suggests that this incredibly diverse microbial community is regulated by host genetic factors, and more importantly, environmental and dietary factors (4)(5)(6). ...
Article
Full-text available
The human body is inhabited by a diverse microbial community that is collectively coined as commensal microbiota. Recent research has greatly advanced our understanding of how the commensal microbiota affects host health. Among the various kinds of pathogenic infections of the host, viral infections constitute one of the most serious public health problems worldwide. During the infection process, viruses may have substantial and intimate interactions with the commensal microbiota. A plethora of evidence suggests that the commensal microbiota regulates and is in turn regulated by invading viruses through diverse mechanisms, thereby having stimulatory or suppressive roles in viral infections. Furthermore, the integrity of the commensal microbiota can be disturbed by invading viruses, causing dysbiosis in the host and further influencing virus infectivity. In the present article, we discuss current insights into the regulation of viral infection by the commensal microbiota. We also draw attention to the disruption of microbiota homeostasis by several viruses.
... The variations in antimonial treatment may be influenced by different factors, including parasite species, the presence of secondary infections within/around the lesion and the spread of drug-resistant parasites. 24,25 As for the prevalence of VL among Syrian migrants, some cases were recorded at the Syrian border. 7 P. syriacus and domestic dogs (Canis lupus familiaris) were identified as the main implicated VL vector and reservoir, respectively. ...
Article
Full-text available
Background: Cutaneous leishmaniasis (CL) is the most prevalent neglected tropical disease among externally displaced people in the Middle East. In recent years, the Lebanese population has increased >30%, mainly due to a mass influx of Syrian migrants, thousands of them carrying CL, among other infectious diseases. Here we revisit the current CL prevalence among refugees in northern Lebanon. Methods: This cohort study was conducted at the Al Bashaer Medical Center in north Lebanon between January and June 2017. A total of 48 randomly selected suspected CL patients were clinically diagnosed by dermatologists and samples were obtained for microscopic examination and molecular identification by polymerase chain reaction restriction fragment length polymorphism. The treatment response to antimonials was assessed each week and was followed for up 6 months. Results: Leishmania tropica was the predominant species (91.7%) followed by Leishmania major (8.3%). Confirmed cases were treated with one to two courses of antimonials and healing was usually achieved after receiving a second course of treatment. Importantly, we show evidence of possible local CL transmission by indigenous sandflies in three separate patients who had no history of recent travel to Syria. Conclusions: This highlights the urgent necessity to implement preventive disease strategies to avoid further dispersion of L. tropica CL in north Lebanon.
... We used L. braziliensis (MHOM/BR/75/M2904 2019) as the target genome and the human genome as background. Genomes from Staphylococcus aureus and Streptococcus pyogenes were also included as background since both are skin commensals that we previously reported to be common members of the dysbiotic skin microbiome on L. braziliensis lesions [32]. We calculated the expected number of perfect match binding sitesacross a range of parasite and host genomes -for each of the 23, 8-mer primer sequences designed by the SWGA algorithm (Supplementary Table 1). ...
Preprint
In Brazil, Leishmania braziliensis is the main causative agent of the neglected tropical disease, cutaneous leishmaniasis (CL). CL caused by L. braziliensis can present on a spectrum of disease severity with a high rate of treatment failure. Yet the parasite factors that contribute to disease presentation and treatment outcome are not well understood, in part because successfully isolating and culturing parasites from patient lesions remains a major technical challenge. Here we describe the development of selective whole genome amplification (SWGA) for Leishmania and show that this method enables culture-independent analysis of parasite genomes obtained directly from primary patient skin samples, allowing us to circumvent artifacts associated with adaptation to culture. We show that SWGA can be applied to multiple Leishmania species residing in different host species, suggesting that this method is broadly useful in both experimental infection models and clinical studies. Finally, we show that parasite genome sequencing data generated by SWGA of skin biopsies collected from patients in Corte de Pedra, Bahia, Brazil, exhibit substantial genetic diversity and can be integrated with published whole genome data from parasite isolates to identify variants associated with high treatment failure rates observed in Northeast Brazil. AUTHOR SUMMARY Leishmania braziliensis is the main cause of cutaneous leishmaniasis in Brazil. Due to limitations in culturing, it is important to study the parasite in a culture-independent manner. We use selective whole genome amplification (SWGA) to explore parasite genomic diversity directly from patient biopsies. This method is inexpensive and can be broadly used to generate parasite genome sequence data sampled from different Leishmania species infecting different mammalian hosts. We found high diversity among the L. braziliensis genomes from Bahia, Brazil, which correlated with geographic location. By integrating these data with publicly available genome sequences from other studies spanning four countries in South America, we identified variants unique to Northeast Brazil that may be linked to high regional rates of treatment failure.
... The relationship between host immunity and pathogen-induced microbial community changes in the skin has been extensively studied in mammals [16,17]. For instance, patients infected with Leishmania braziliensis develop skin dysbiosis, which is characterized by increases in the abundance of Staphylococcus and/or Streptococcus, both of which can induce inflammation [18]. Some studies in fish have also evaluated the association between pathogens, skin immunity, and microbial community structure [19]. ...
Article
Full-text available
The skin is the largest organ on the surface of vertebrates, which not only acts as the first line of defense against pathogens but also harbors diverse symbiotic microorganisms. The complex interaction between skin immunity, pathogens, and commensal bacteria has been extensively studied in mammals. However, little is known regarding the effects of viral infection on the skin immune response and microbial composition in teleost fish. In this study, we exposed rainbow trout (Oncorhynchus mykiss) to infectious hematopoietic necrosis virus (IHNV) by immersion infection. Through pathogen load detection and pathological evaluation, we confirmed that IHNV successfully invaded the rainbow trout, causing severe damage to the epidermis of the skin. qPCR analyses revealed that IHNV invasion significantly upregulated antiviral genes and elicited strong innate immune responses. Transcriptome analyses indicated that IHNV challenge induced strong antiviral responses mediated by pattern recognition receptor (PRR) signaling pathways in the early stage of the infection (4 days post-infection (dpi)), and an extremely strong antibacterial immune response occurred at 14 dpi. Our 16S rRNA sequencing results indicated that the skin microbial community of IHNV-infected fish was significantly richer and more diverse. Particularly, the infected fish exhibited a decrease in Proteobacteria accompanied by an increase in Actinobacteria. Furthermore, IHNV invasion favored the colonization of opportunistic pathogens such as Rhodococcus and Vibrio on the skin, especially in the later stage of infection, leading to dysbiosis. Our findings suggest that IHNV invasion is associated with skin microbiota dysbiosis and could thus lead to secondary bacterial infection.
... Based on the parasite species, organs infected, and symptoms produced, leishmaniasis presents in three different forms: mucocutaneous, cutaneous (CL), and visceral (VL), also known as kala-azar (28) ( Table 1). The severity of disease progression is dictated by a number of factors, including the infecting parasite dose (29,30), composition of sand fly saliva (31), site of infection (32), degree of tissue damage (17), host skin microbiome (33,34) and the sand fly gut microbiota (35)(36)(37). The most important parameter that dictates disease severity is the type of immune response developed by the host. ...
Article
Full-text available
Intravital microscopy, such as 2-photon microscopy, is now a mainstay in immunological research to visually characterize immune cell dynamics during homeostasis and pathogen infections. This approach has been especially beneficial in describing the complex process of host immune responses to parasitic infections in vivo , such as Leishmania. Human-parasite co-evolution has endowed parasites with multiple strategies to subvert host immunity in order to establish chronic infections and ensure human-to-human transmission. While much focus has been placed on viral and bacterial infections, intravital microscopy studies during parasitic infections have been comparatively sparse. In this review, we will discuss how in vivo microscopy has provided important insights into the generation of innate and adaptive immunity in various organs during parasitic infections, with a primary focus on Leishmania . We highlight how microscopy-based approaches may be key to providing mechanistic insights into Leishmania persistence in vivo and to devise strategies for better parasite control.
... Changes we observed between AR hellbenders of varying toe lesion severity could represent a decreased ability to maintain an optimal microbial community as disease progresses in an individual. Another explanation could be that local microbial changes due to chronic lesions can eventually generate changes over the entire skin surface as has been seen around chronic ulceration due to leishmaniasis in humans (Gimblet et al. 2017). Alternatively, shifts in microbial communities could be the main mechanism by which lesions manifest, and lesion severity represent a sequela of this dysbiosis that manifests speci cally in an area of increased use (e.g. ...
Preprint
Full-text available
Background Skin microbiomes are important components of skin health and have been shown to contribute to immunity in amphibians, especially against the chytrid fungus, Batrachochytrium dendrobatidis ( Bd ). Hellbenders ( Cryptobranchus alleganiensis ) are large aquatic amphibians (Order Caudata) native to the eastern United States that have experienced population declines of both the Ozark and eastern subspecies, C. a. bishopi and C. a. alleganiensis , respectively. In addition, ulcerative non-healing toe lesions have become increasingly prevalent in C. a. bishopi , in Arkansas (AR) where populations are now reduced to a single river. To evaluate the potential impacts of both chronic toe lesions and Bd on hellbender health, we compared dorsal skin microbial assemblages based on 16S rRNA gene amplicons between a declining Ozark hellbender population in Arkansas (AR) presenting lesions and a reference, recruiting, lesion-free, population of eastern hellbenders in eastern Tennessee (ETN). We further evaluated effects of mass and life stage across both subspecies, as well as toe lesion severity and Bd infection status within AR, to better understand the associations between microbiomes and disease in a wild salamander.ResultsWe found skin of ETN hellbenders to have greater bacterial alpha diversity compared to AR, with this disparity decreasing as Hill number order increased. Conversely, within AR, animals with more severe lesions had decreased alpha diversity than those with mild lesions, which became more pronounced with increasing Hill number. Further, the average microbial assemblage structure differed between ETN and AR. Specifically, AR communities displayed increased beta diversity compared to those from ETN, which appeared to be linked to toe lesion severity. Neither size class (mass) nor Bd infection status had a significant effect on alpha or beta diversity. Taxonomic analysis revealed ETN to have greater OTU abundance of phylum Cyanobacteria 24.3%) compared to AR (5.9%); whereas AR had increased abundance of Proteobacteria (48.5%), Firmicutes (9.1%), and Synergistetes (1.5%), in comparison to ETN (31.5%, 2.6%, 0.2%, respectively).Conclusions Results demonstrate that eastern hellbenders of ETN have richer and less dispersed dorsal skin bacterial assemblages compared to Ozark hellbenders of AR. Furthermore, we suggest that increased severity of toe lesions may be linked to systemic changes resulting in skin microbial dysbiosis, independent of Bd infection. Although lesions remain to have an unknown etiology, this study is another step towards understanding skin bacterial microbiomes in hellbenders, and their potential associations with chronic disease.
... Vice versa, biofilms could affect the CL wound microenvironment as well. It has been found that the altered bacterial burden can change the immune microenvironment of CL wounds by recruiting more neutrophils, IL-1β and activation of IL-17A [16]. Investigating these changes would be important to open new paths in the management of CL wounds. ...
Article
Full-text available
Cutaneous leishmaniasis (CL) lesions are chronic and result in disfiguring scars. The microbiological aspects of these wounds have not been systematically investigated. We have recently reported that 61.5% of CL wounds in a Sri Lankan cohort harboured bacterial biofilms, mainly composed of bacilli, Enterobacteriaceae , and Pseudomonas, which could delay wound healing. We have additionally reported that biofilms were significantly associated patients over 40 years of age, discharge, pain and/or itching of the wound, and high pus cell counts. Using this as background knowledge and other relevant literature, we highlight the importance of investigating the role of biofilms in CL wound healing, clinical indicators, cost-effective laboratory tests involving less invasive sampling techniques for diagnosing biofilms and potential therapeutic options for biofilm-containing CL wounds, such as adjunctive application of wound debridement and antimicrobial treatment along with anti-parasitic drugs.
... Cutaneous leishmaniasis is characterized by augmented Staphylococcus and/ or Streptococcus infections and skin inflammation. Interestingly, in murine models this dysbiosis was found to be transferable to naive mice [25] . Similarly, visceral leishmaniasis (VL) patients are more susceptible to fatal nosocomial secondary bacterial infections (Pseudomonas aeruginosa and Staphylococcus aureus) [26] . ...
... T he human skin microbiome plays an important role in both health and disease. It is involved in immune training, pathogen exclusion, and its dysbiotic state can often exacerbate disease (1)(2)(3). Modern-day practices have attenuated the skin microbiome, with uncertain consequences (4)(5)(6). Products formulated to alter the skin microbiome community composition can be used for therapeutic purposes (7), highlighting its centrality in health and disease. ...
Article
Full-text available
The bacterial population that colonizes the human face imparts physiochemical and physiological effects on the facial skin. These skin-microbe interactions impact dermatological, cosmetic and skincare applications due to the centrality of the human face in daily interactions. However, fine-scale characterization of the human face skin microbiome is lacking. Using 16S rRNA sequencing and 3D cartography, this study plotted and characterized the facial skin microbiome in high-definition, based on 1,649 samples from 12 individuals. Analysis yielded a number of novel insights, including that of the relative uniformity of skin microbiome composition within skin sites, site localization of certain microbes, and the interpersonal variability of the skin microbiome. The results show that high-resolution topographical mapping of the skin microbiome is a powerful tool for studying the human skin microbiome. Despite a decade of skin microbiome research, there is still much to be discovered.
... Although Lachnospiraceae in the gut are considered beneficial (Sorbara et al., 2020), the role for Lachnospiraceae on the skin has not been defined. However, Lachnospiraceae have previously been identified on the skin of mice (Gimblet et al., 2017) and topical exposure to antibiotics was shown to reduce the abundance of Lachnospiraceae on mouse skin (SanMiguel et al., 2017). The skin microbiome is critical for maintaining homeostasis of the skin, supporting barrier integrity, and resisting colonization of pathogens (Baldwin et al., 2017;Byrd et al., 2018). ...
Article
Triclosan is an antimicrobial chemical used in healthcare settings that can be absorbed through the skin. Exposure to triclosan has been positively associated with food and aeroallergy and asthma exacerbation in humans and, although not directly sensitizing, has been demonstrated to augment the allergic response in a mouse model of asthma. The skin barrier and microbiome are thought to play important roles in regulating inflammation and allergy and disruptions may contribute to development of allergic disease. To investigate potential connections of the skin barrier and microbiome with immune responses to triclosan, SKH1 mice were exposed dermally to triclosan (0.5-2%) or vehicle for up to 7 consecutive days. Exposure to 2% triclosan for 5-7 days on the skin was shown to increase trans-epidermal water loss levels. Seven days of dermal exposure to triclosan decreased filaggrin 2 and keratin 10 expression, but increased filaggrin and keratin 14 protein along with the danger signal S100a8 and interleukin-4. Dermal exposure to triclosan for 7 days also altered the alpha and beta diversity of the skin and gut microbiome. Specifically, dermal triclosan exposure increased the relative abundance of the Firmicutes family, Lachnospiraceae on the skin but decreased the abundance of Firmicutes family, Ruminococcaceae in the gut. Collectively, these results demonstrate that repeated dermal exposure to the antimicrobial chemical triclosan alters the skin barrier integrity and microbiome in mice, suggesting that these changes may contribute to the increase in allergic immune responses following dermal exposure to triclosan.
... We also predict macrophages are exposed to these molecules during L. major infection. LPS may activate skin macrophages during CL given the presence of the microbiome and the compromised integrity of the skin [39]. IFN is also elevated at the site of infection due to the host Th1 immune response [3]. ...
Preprint
Leishmanial skin lesions are characterized by inflammatory hypoxia alongside the activation of hypoxia inducible factors, HIF-1a and HIF-2a, and subsequent expression of the HIF-a target VEGF-A during Leishmania major infection. However, the factors responsible for HIF-a activation are not known. We hypothesize hypoxia and pro-inflammatory stimuli contribute to HIF-a activation during infection. RNASeq on leishmanial lesions found transcripts associated with HIF-1a signaling are induced. To determine whether hypoxia contributes to HIF-a activation, we followed the fate of myeloid cells infiltrating from the blood and into hypoxic lesions. Recruited myeloid cells experience hypoxia when they enter inflamed lesions, and the length of time in lesions increases their hypoxic signature. To determine whether pro-inflammatory stimuli in the inflamed tissue can also influence HIF-a activation, we subjected macrophages to various pro-inflammatory stimuli and measured VEGF-A. While parasites alone did not induce VEGF-A, and pro-inflammatory stimuli only modestly induce VEGF-A, HIF- stabilization increases VEGF-A during infection. HIF-a stabilization does not impact parasite entry, growth or killing. Alternatively, the absence of ARNT/HIF- signaling enhances parasite internalization. Altogether, these findings suggest HIF-a is active during infection, and while macrophage HIF-a activation promotes lymphatic remodeling through VEGF-A production, HIF-a activation does not impact parasite internalization or control.
... These outcomes were related to smaller numbers of IFN-g and TNF-a T CD4 producing cells at the site of infection (37). In this work we have not addressed either the local Leishmania specific T cell response regarding to cytokine production or any T cell response towards skin microbiota that might occur during the dysbiosis promoted by the infection (59). We did find higher arginase I activity in lesions from germ-free mice, despite the same levels of IL-4 and IL-10 production by specific recall of Leishmania antigen response in the draining lymph nodes, which can induce arginase I expression (60), and are associated with parasite replication (23,49). ...
Article
Full-text available
Innate immune cells present a dual role during leishmaniasis: they constitute the first line of host defense but are also the main host cells for the parasite. Response against the infection that results in the control of parasite growth and lesion healing depends on activation of macrophages into a classical activated phenotype. We report an essential role for the microbiota in driving macrophage and monocyte-derived macrophage activation towards a resistance phenotype against Leishmania major infection in mice. Both germ-free and dysbiotic mice showed a higher number of myeloid innate cells in lesions and increased number of infected cells, mainly dermal resident and inflammatory macrophages. Despite developing a Th1 immune response characterized by the same levels of IFN-γ production as the conventional mice, germ-free mice presented reduced numbers of iNOS+ macrophages at the peak of infection. Absence or disturbance of host microbiota impaired the capacity of bone marrow-derived macrophage to be activated for Leishmania killing in vitro, even when stimulated by Th1 cytokines. These cells presented reduced expression of inos mRNA, and diminished production of microbicidal molecules, such as ROS, while presenting a permissive activation status, characterized by increased expression of arginase I and il-10 mRNA and higher arginase activity. Colonization of germ-free mice with complete microbiota from conventional mice rescued their ability to control the infection. This study demonstrates the essential role of host microbiota on innate immune response against L. major infection, driving host macrophages to a resistance phenotype.
... As we were able to greatly enhance LgyLRV1+ induced iNOS induction by providing additional inflammatory stimuli (Figures 2A-F), we assumed that the iNOS-coping strategy of LgyLRV1+ lied within suppression of NF-kB activation. While artificial in our in vitro setting, such additional inflammatory stimuli can naturally arise from harmless commensals present in the skin and known to impact inflammatory reactions (Naik et al., 2012;Belkaid and Tamoutounour, 2016;Gimblet et al., 2017) or from sandfly gut microbiota egested together with the parasites (Dey et al., 2018). Such immunologically cross-reactive environment would serve as an additional stimulus for a parasite to evolutionary develop iNOSmitigation mechanisms. ...
Article
Full-text available
Inducible nitric oxide synthase (iNOS) is essential to the production of nitric oxide (NO), an efficient effector molecule against intracellular human pathogens such as Leishmania protozoan parasites. Some strains of Leishmania are known to bear a viral endosymbiont termed Leishmania RNA virus 1 (LRV1). Recognition of LRV1 by the innate immune sensor Toll-like receptor-3 (TLR3) leads to conditions worsening the disease severity in mice. This process is governed by type I interferon (type I IFNs) arising downstream of TLR3 stimulation and favoring the formation of secondary metastatic lesions. The formation of these lesions is mediated by the inflammatory cytokine IL-17A and occurs in the absence, or low level of, protective cytokine IFN-γ. Here, we described that the presence of LRV1 led to the initial expression of iNOS and low production of NO that failed to control infection. We subsequently showed that LRV1-triggered type I IFN was essential but insufficient to induce robust iNOS induction, which requires strong activation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). Leishmania guyanensis carrying LRV1 ( Lgy LRV1+) parasites mitigated strong iNOS production by limiting NF-kB activation via the induction of tumor necrosis factor-alpha-induced protein 3 (TNFAIP3), also known as A20. Moreover, our data suggested that production of LRV1-induced iNOS could be correlated with parasite dissemination and metastasis via elevated secretion of IL-17A in the draining lymph nodes. Our findings support an additional strategy by which LRV1-bearing Leishmania guyanensis evaded killing by nitric oxide and suggest that low levels of LRV1-induced NO might contribute to parasite metastasis.
... The skin microbiota is strongly correlated with the immune system [34,35]. The protective function of the skin is ensured by the epidermis, while the anti-inflammatory and antimicrobial molecules are produced by keratinocytes and immune cells. ...
Article
Full-text available
Skin harbors an important microbial ecosystem — the skin microbiota that is in homeostasis with its host and is beneficial for human health. Cosmetic products have the potential to interfere with this microbial community; therefore their impact should be assessed. The aim of this review is to highlight the importance of skin microbiota in the cosmetic industry. Several studies determined that cosmetic ingredients have the potential to disrupt the skin microbiota equilibrium leading to the development of skin diseases and dysregulation of immune response. These studies led their investigation by using different methodologies and models, concluding that methods must be chosen according to the aim of the study, the skin site to be evaluated, and the target population of the cosmetics. Overall, it is crucial to test the impact of cosmetics in the skin microbiota and to stablish standard procedures, as well as specific criteria that allow to classify a cosmetic product as skin microbiota friendly.
... It has been reported that the normal flora of the skin can influence allergic and autoimmune responses, assist wound healing and initiate antimicrobial defence. The skin microbiota in CL patients develop dysbiotic skin microbiota which essentially reduce the diversity of microbial species and allow the predominance of Staphylococcus and or Streptococcus [131]. The dysbiotic skin microbiota heighten skin inflammatory responses. ...
Article
Full-text available
Nanomedicine strategies were first adapted and successfully translated to clinical application for diseases, such as cancer and diabetes. These strategies would no doubt benefit unmet diseases needs as in the case of leishmaniasis. The latter causes skin sores in the cutaneous form and affects internal organs in the visceral form. Treatment of cutaneous leishmaniasis (CL) aims at accelerating wound healing, reducing scarring and cosmetic morbidity, preventing parasite transmission and relapse. Unfortunately, available treatments show only suboptimal effectiveness and none of them were designed specifically for this disease condition. Tissue regeneration using nano-based devices coupled with drug delivery are currently being used in clinic to address diabetic wounds. Thus, in this review, we analyse the current treatment options and attempt to critically analyse the use of nanomedicine-based strategies to address CL wounds in view of achieving scarless wound healing, targeting secondary bacterial infection and lowering drug toxicity.
... Milder infections have self-healing mechanisms although with disfiguring, while severe infections have diffuse cutaneous leishmaniasis (DCL), disparaging uncontrolled mucocutaneous and visceral ramifications, the latter being most fatal of all. A variant pattern of parasite invasion is recorded in the clinical manifestations, where cutaneous leishmaniasis (CL) has restriction of parasite at site of sandfly bite, mucocutaneous leishmaniasis (MCL) advances to mucous and skin membranes of nose and mouth, and visceral leishmaniases depict uncontrolled spread and replication of parasite through host reticuloendothelial system infesting the mucosal/sub-mucosal digestive tract and pathological liver and spleen lesions [5][6][7]. ...
Article
Full-text available
The infectious paradigms have recently led to the recognition interplay of complex phenomenon underpinning disease diagnosis and prognosis. Evidently, parasitic infection studies are depicting converging trends of the epigenetic, environmental, and microbiome contributions, assisting pathogen-directed modulations of host biological system. The molecular details of epigenetic variations and memory, along with the multi-omics data at the interface of the host–pathogen level becomes strong indicator of immune cell plasticity, differentiation, and pathogen survival. Despite being one of the most important aspects of the disease’s etiopathology, the epigenetic regulation of host–pathogen interactions and evolutionary epigenetics have received little attention thus far. Recent evidence has focused on the growing need to link epigenetic and microbiome modulations on parasite phenotypic plasticity and pathogen-induced host phenotypic plasticity for designing futuristic therapeutic regimes. Leishmaniasis is a neglected tropical illness with varying degrees of disease severity that is linked to a trans-species and epigenetic heredity process, including the pathogen-induced host and strain-specific modulations. The review configures research findings aligning to the epigenetic epidemiology niche, involving co-evolutionary epigenetic inheritance and plasticity disease models. The epigenetic exemplars focus on the host–pathogen interactome expanse at the macrophage—inflammasome axis.
... We also predict that macrophages are exposed to these molecules during L. major infection. LPS may activate skin macrophages during CL, given the presence of the microbiome and the compromised integrity of the skin [38]. IFNγ is also elevated at the site of infection due to the host Th1 immune response [3]. ...
Article
Full-text available
Leishmanial skin lesions are characterized by inflammatory hypoxia alongside the activation of hypoxia-inducible factors, HIF-1α and HIF-2α, and subsequent expression of the HIF-α target VEGF-A during Leishmania major infection. However, the factors responsible for HIF-α activation are not known. We hypothesize that hypoxia and proinflammatory stimuli contribute to HIF-α activation during infection. RNA-Seq of leishmanial lesions revealed that transcripts associated with HIF-1α signaling were induced. To determine whether hypoxia contributes to HIF-α activation, we followed the fate of myeloid cells infiltrating from the blood and into hypoxic lesions. Recruited myeloid cells experienced hypoxia when they entered inflamed lesions, and the length of time in lesions increased their hypoxic signature. To determine whether proinflammatory stimuli in the inflamed tissue can also influence HIF-α activation, we subjected macrophages to various proinflammatory stimuli and measured VEGF-A. While parasites alone did not induce VEGF-A, and proinflammatory stimuli only modestly induced VEGF-A, HIF-α stabilization increased VEGF-A during infection. HIF-α stabilization did not impact parasite entry, growth, or killing. Conversely, the absence of ARNT/HIF-α signaling enhanced parasite internalization. Altogether, these findings suggest that HIF-α is active during infection, and while macrophage HIF-α activation promotes lymphatic remodeling through VEGF-A production, HIF-α activation does not impact parasite internalization or control.
Article
Full-text available
Interactions between pathogens, host microbiota and the immune system influence many physiological and pathological processes. In the 20 th century, widespread dermal vaccination with vaccinia virus (VACV) led to the eradication of smallpox but how VACV interacts with the microbiota and whether this influences the efficacy of vaccination are largely unknown. Here we report that intradermal vaccination with VACV induces a large increase in the number of commensal bacteria in infected tissue, which enhance recruitment of inflammatory cells, promote tissue damage and influence the host response. Treatment of vaccinated specific-pathogen-free (SPF) mice with antibiotic, or infection of genetically-matched germ-free (GF) animals caused smaller lesions without alteration in virus titre. Tissue damage correlated with enhanced neutrophil and T cell infiltration and levels of pro-inflammatory tissue cytokines and chemokines. One month after vaccination, GF and both groups of SPF mice had equal numbers of VACV-specific CD8 ⁺ T cells and were protected from disease induced by VACV challenge, despite lower levels of VACV-neutralising antibodies observed in GF animals. Thus, skin microbiota may provide an adjuvant-like stimulus during vaccination with VACV and influence the host response to vaccination.
Article
The prime objective of this study was to develop amphotericin B (AMB) and rifampicin (RIF) co-loaded transfersomal gel (AMB-RIF co-loaded TFG) for effective treatment of cutaneous leishmaniasis (CL). AMB-RIF co-loaded TF was prepared by the thin-film hydration method and was optimized based on particle size, polydispersity index (PDI), zeta potential, entrapment efficiency (%EE), and deformability index. Similarly, AMB-RIF co-loaded TFG was characterized in terms of rheology, spread ability, and pH. In vitro, ex vivo, and in vivo assays were performed to evaluate AMB-RIF co-loaded TF as a potential treatment option for CL. The optimized formulation had vesicles in nanosize range (167 nm) with suitable PDI (0.106), zeta potential (− 19.05 mV), and excellent %EE of RIF (66%) and AMB (85%). Moreover, it had appropriate deformability index (0.952). Additionally, AMB-RIF co-loaded TFG demonstrated suitable rheological behavior for topical application. AMB-RIF co-loaded TF and AMB-RIF co-loaded TFG showed sustained release of the incorporated drugs as compared to AMB-RIF suspension. Furthermore, RIF permeation from AMB-RIF co-loaded TF and AMB-RIF co-loaded TFG was enhanced fivefold and threefold, whereas AMB permeation was enhanced by eightfold and 6.6-fold, respectively. The significantly different IC50, higher CC50, and FIC50 (p < 0.5) showed synergistic antileishmanial potential of AMB-RIF co-loaded TF. Likewise, reduced lesion size and parasitic burden in AMB-RIF co-loaded TF–treated mouse group further established the antileishmanial effect of the optimized formulation. Besides, AMB-RIF co-loaded TFG showed a better safety profile. This study concluded that TFG may be a suitable carrier for co-delivery of AMB-RIF when administered topically for the treatment of CL.Graphical abstract
Article
Full-text available
Enteric viruses can directly infect the mammalian gastrointestinal tract which is home to a diverse community of commensal microorganism. Emerging evidence suggests that certain enteric viruses utilize these microbiotas to promote infection. Multiple viruses from different viral families have been indicated to bind directly to microbiota or bacterial components to enhance viral growth, pathogenesis, and transmission. These data indicated that the concept of a single virus infecting a single cell, independent of the environment, needs to be reevaluated. In this review, we will discuss the current knowledge of enteric virus-microbiota interactions and discuss the implications for viral pathogenesis and transmission.
Article
Full-text available
Human African trypanosomes rely for their transmission on tsetse flies (Glossina sp.) that inoculate parasites into the skin during blood feeding. The absence of a protective vaccine, limited knowledge about the infection immunology, and the existence of asymptomatic carriers sustaining transmission are major outstanding challenges towards elimination. All these relate to the skin where (i) parasites persist and transmit to tsetse flies and (ii) a successful vaccination strategy should ideally be effective. Host immune processes and parasite strategies that underlie early infection and skin tropism are essential aspects to comprehend the transmission-success of trypanosomes and the failure in vaccine development. Recent insights into the early infection establishment may pave the way to novel strategies aimed at blocking transmission.
Article
Full-text available
The endemic strain of Leishmania donovani in Sri Lanka causes cutaneous leishmaniasis (CL) rather than more common visceral form. We have visualized biofilms and profiled the microbiome of lesions and unaffected skin in thirty-nine CL patients. Twenty-four lesions (61.5%) were biofilm-positive according to fluorescence in situ hybridization. Biopsies of biofilm-positive lesions were dominated by Pseudomonas , class Bacilli and Enterobacteriaceae and distinguished by significantly lower community evenness. Higher relative abundance of a class Bacilli OTU was detected in wound swabs versus contralateral skin. Wound swabs and biopsies had significantly distinct microbiome profiles and lower diversity compared to unaffected skin. Greater abundances of potentially pathogenic organisms were observed in wet ulcers, lesions with high parasite loads and large wounds. In summary, more than half of L. donovani associated CL wounds harboured biofilms and the wounds exhibited a distinct, less diverse, microbiome than unaffected skin.
Article
The symbiotic microbiota is nowadays regarded as a human “invisible organ”, its imbalance has been shown to be associated with many diseases. Besides, the progress of diseases can in turn change the internal structure of microbiota. Some diseases have shown their unique microbiota markers that may be potential therapeutic targets. Therefore, modulating microbiota may be a powerful strategy for diseases treatment. However, conventional microbiota modulation strategies lack selectivity and are suffer from side effects. In recent years, with the increasing challenge of antibiotic resistance, bacteriophage (phage) therapy has gradually presented its potential to treat drug-resistant infections. Phages are viruses that infect bacteria, with high selectivity for specific bacteria and almost no tropism for mammalian cells. Studies showed that phage-mediated precise modulation of microbiota has achieved great success in diseases treatment. Here, we briefly summarized the treatment strategies of phage-mediated modulation of microbiota, and discussed prospect of possible development in this field.
Preprint
Full-text available
Motivation: Microbial communities play important roles in the function and maintenance of various biosystems, ranging from the human body to the environment. A major challenge in microbiome research is the classification of microbial communities of different environments or host phenotypes. The most common and cost-effective approach for such studies to date is 16S rRNA gene sequencing. Recent falls in sequencing costs have increased the demand for simple, efficient, and accurate methods for rapid detection or diagnosis with proved applications in medicine, agriculture, and forensic science. We describe a reference- and alignment-free approach for predicting environments and host phenotypes from 16S rRNA gene sequencing based on k-mer representations that benefits from a bootstrapping framework for investigating the sufficiency of shallow sub-samples. Deep learning methods as well as classical approaches were explored for predicting environments and host phenotypes. Results: k-mer distribution of shallow sub-samples outperformed the computationally costly Operational Taxonomic Unit (OTU) features in the tasks of body-site identification and Crohn's disease prediction. Aside from being more accurate, using k-mer features in shallow sub-samples allows (i) skipping computationally costly sequence alignments required in OTU-picking, and (ii) provided a proof of concept for the sufficiency of shallow and short-length 16S rRNA sequencing for phenotype prediction. In addition, k-mer features predicted representative 16S rRNA gene sequences of 18 ecological environments, and 5 organismal environments with high macro-F1 scores of 0.88 and 0.87. For large datasets, deep learning outperformed classical methods such as Random Forest and SVM. Availability: The software and datasets are available at https://llp.berkeley.edu/micropheno.
Chapter
Human beings house a multitude of microorganisms that control human health and disease progression. Presently, human microbiome and microbiota research is getting substantial attention in the field of infectious disease research. Growing research evidence shows a compositional and functional relationship between the human microbiome and disease states, and also proves that the microbiota and microbiome may be used for the expansion of therapeutic strategies against infectious diseases. Therefore, there is an increasing need to integrate and relate the research findings arising from the nascent microbiome research with infectious diseases. The understanding of the complete human microbiota/microbiome is limited by culture-dependent microbial techniques, but these limitations can be overcome by contemporary developments in culture-independent, high throughput methods such as next-generation sequencing and mass spectrometry for genome and proteome profiling, respectively. This chapter focuses on the recent advancements in metagenomics and metatranscriptomics methods utilized to characterize microbial genome and proteome and thereby helps us understand the relationship between microbial populations and human health.
Article
Modern medicine has long studied the mechanism and impact of pathogenic microbes on human hosts, but has only recently shifted attention toward the complex and vital roles that commensal and probiotic microbes play in both health and dysbiosis. Fueled by an enhanced appreciation of the human-microbe holobiont, the past decade has yielded countless insights and established many new avenues of investigation in this area. In this review, we discuss advances, limitations, and emerging frontiers for microbes as agents of health maintenance, disease prevention, and cure. We highlight the flexibility of microbial therapeutics across disease states, with special consideration for the rational engineering of microbes toward precision medicine outcomes. As the field advances, we anticipate that tools of synthetic biology will be increasingly employed to engineer functional living therapeutics with the potential to address longstanding limitations of traditional drugs.
Article
Today, more than a billion people – one-sixth of the world’s population – are suffering from neglected tropical diseases. Human African trypanosomiasis, Chagas disease, and leishmaniasis are neglected tropical diseases caused by protozoan parasites belonging to the genera Trypanosoma and Leishmania. About half a million people living in tropical and subtropical regions of the world are at risk of contracting one of these three infections. Kinetoplastids have complex life cycles with different morphologies and unique physiological requirements at each lifecycle stage. This review covers the latest findings on metabolic pathways impacting disease pathogenesis of kinetoplastids within the mammalian host. Nutrient availability is a key factor shaping in vivo parasite metabolism; thus, kinetoplastids display significant metabolic flexibility. Proteomic and transcriptomic profiles show that intracellular trypanosomatids are able to switch to an energy-efficient metabolism within the mammalian host system. Host metabolic changes can also favor parasite persistence, and contribute to symptom development, in a location-specific fashion. Ultimately, targeted and untargeted metabolomics studies have been a valuable approach to elucidate the specific biochemical pathways affected by infection within the host, leading to translational drug development and diagnostic insights.
Thesis
Le Leishmania RNA virus (LRV), un virus à ARN double brin retrouvé chez certaines Leishmania, pourrait constituer un facteur d’aggravation des leishmanioses tégumentaires. En Guyane Française, ce virus est retrouvé dans plus de 80% des isolats de L. guyanensis, dont la plupart sont issus des communes de l’intérieur. La présence de ce virus dans les Leishmania ne semble pas influencer la sensibilité in vitro des parasites aux principaux antiparasitaires, mais pourrait augmenter de 27% le risque d’échec thérapeutique et de rechutes chez les patients traités à la pentamidine. L’analyse génétique des LRV, dont le but était d'identifier l’implication de clusters dans la maladie, a permis de déterminer six groupes, dont deux majoritaires. Toutefois, aucun de ces clusters ne semblait être associé aux échecs thérapeutiques primaires. Le LRV ne semble être impliqué que dans les réactivations de la maladie. Ainsi, l’étude d’un plus grand nombre de sujets présentant une réactivation de la maladie permettrait de confirmer l’implication du LRV dans ces rechutes et de déterminer si un génotype de LRV particulier serait impliqué.
Article
The period between the infective sandfly bites and appearance of cutaneous leishmaniasis (CL) lesions is still hypothetical and little studied. This work aimed at assessing the incubation time of zoonotic CL (ZCL) due to Leishmania major using a standardized methodology. The retrospective analysis used the epidemiological, clinical, and biological information available in the database recording all the CL cases diagnosed at the Parasitology Department of the Pasteur Institute of Tunis during 2015-2019. It allowed for the selection of 92 privileged observations 1) of confirmed CL cases with presentation suggestive of ZCL form 2) living in northern regions free of ZCL 3) with a single infective trip of less than a week to ZCL foci during transmission season and 4) with accurate dates of travel and onset of lesions. Incubation length computed in this population ranged from 1 to 21 weeks, with a median of 5 weeks (interquartile range: 3-8.5 weeks).
Article
Full-text available
Localised cutaneous leishmaniasis (LCL) is the most common form of cutaneous leishmaniasis characterised by single or multiple painless chronic ulcers, which commonly presents with secondary bacterial infection. Previous culture-based studies have found staphylococci, streptococci, and opportunistic pathogenic bacteria in LCL lesions, but there have been no comparisons to normal skin. In addition, this approach has strong bias for determining bacterial composition. The present study tested the hypothesis that bacterial communities in LCL lesions differ from those found on healthy skin (HS). Using a high throughput amplicon sequencing approach, which allows for better populational evaluation due to greater depth coverage and the Quantitative Insights Into Microbial Ecology pipeline, we compared the microbiological signature of LCL lesions with that of contralateral HS from the same individuals.Streptococcus, Staphylococcus,Fusobacterium and other strict or facultative anaerobic bacteria composed the LCL microbiome. Aerobic and facultative anaerobic bacteria found in HS, including environmental bacteria, were significantly decreased in LCL lesions (p < 0.01). This paper presents the first comprehensive microbiome identification from LCL lesions with next generation sequence methodology and shows a marked reduction of bacterial diversity in the lesions.
Article
Full-text available
Chronic inflammatory disorders are thought to arise due to an interplay between predisposing host genetics and environmental factors. For example, the onset of inflammatory bowel disease is associated with enteric proteobacterial infection, yet the mechanistic basis for this association is unclear. We have shown previously that genetic defiency in TLR1 promotes acute enteric infection by the proteobacteria Yersinia enterocolitica. Examining that model further, we uncovered an altered cellular immune response that promotes the recruitment of neutrophils which in turn increases metabolism of the respiratory electron acceptor tetrathionate by Yersinia. These events drive permanent alterations in anti-commensal immunity, microbiota composition, and chronic inflammation, which persist long after Yersinia clearence. Deletion of the bacterial genes involved in tetrathionate respiration or treatment using targeted probiotics could prevent microbiota alterations and inflammation. Thus, acute infection can drive long term immune and microbiota alterations leading to chronic inflammatory disease in genetically predisposed individuals.
Article
Full-text available
Mice lacking three epidermal barrier proteins-envoplakin, periplakin and involucrin-(EPI-/- mice) have a defective cornified layer, reduced epidermal γδ T cells, increased dermal CD4+ T cells and are resistant to developing skin tumours. The tumour-protective mechanism involves signalling between Rae-1 expressing keratinocytes and the Natural Killer Group 2D (NKG2D) receptor on immune cells, which also plays a role in host defences against infection. Given the emerging link between bacteria and cancer, we investigated whether EPI-/- mice have an altered skin microbiota. The bacterial phyla were similar in wild type and EPI-/- skin. However, bacteria were 3-fold more abundant in EPI-/- skin and penetrated deeper into the epidermis. The major epithelial defense mechanism against bacteria is production of antimicrobial proteins (AMPs). EPI-/- skin exhibited enhanced expression of antimicrobial peptides. However, reducing the bacterial load by antibiotic treatment or breeding mice under specific pathogen-free conditions did not reduce AMP expression or alleviate the abnormalities in T cell populations. We conclude that the atopic characteristics of EPI-/- skin are a consequence of the defective barrier rather than a response to the increased bacterial load. It is therefore unlikely that the increase in skin microbiota contributes directly to the observed cancer resistance.Journal of Investigative Dermatology accepted article preview online, 30 September 2015. doi:10.1038/jid.2015.383.
Article
Full-text available
Cutaneous leishmaniasis is a disease characterized by ulcerating skin lesions, the resolution of which requires an effective, but regulated, immune response that limits parasite growth without causing permanent tissue damage. While mechanisms that control the parasites have been well studied, the factors regulating immunopathologic responses are less well understood. IL-22, a member of the IL-10 family of cytokines, can contribute to wound healing, but in other instances promotes pathology. Here we investigated the role of IL-22 during leishmania infection, and found that IL-22 limits leishmania-induced pathology when a certain threshold of damage is induced by a high dose of parasites. Il22-/- mice developed more severe disease than wild-type mice, with significantly more pathology at the site of infection, and in some cases permanent loss of tissue. The increased inflammation was not due to an increased parasite burden, but rather was associated with the loss of a wound healing phenotype in keratinocytes. Taken together, these studies demonstrate that during cutaneous leishmaniasis, IL-22 can play a previously unappreciated role in controlling leishmania-induced immunopathology.
Article
Full-text available
The skin represents the primary interface between the host and the environment. This organ is also home to trillions of microorganisms that play an important role in tissue homeostasis and local immunity. Skin microbial communities are highly diverse and can be remodelled over time or in response to environmental challenges. How, in the context of this complexity, individual commensal microorganisms may differentially modulate skin immunity and the consequences of these responses for tissue physiology remains unclear. Here we show that defined commensals dominantly affect skin immunity and identify the cellular mediators involved in this specification. In particular, colonization with Staphylococcus epidermidis induces IL-17A(+) CD8(+) T cells that home to the epidermis, enhance innate barrier immunity and limit pathogen invasion. Commensal-specific T-cell responses result from the coordinated action of skin-resident dendritic cell subsets and are not associated with inflammation, revealing that tissue-resident cells are poised to sense and respond to alterations in microbial communities. This interaction may represent an evolutionary means by which the skin immune system uses fluctuating commensal signals to calibrate barrier immunity and provide heterologous protection against invasive pathogens. These findings reveal that the skin immune landscape is a highly dynamic environment that can be rapidly and specifically remodelled by encounters with defined commensals, findings that have profound implications for our understanding of tissue-specific immunity and pathologies.
Article
Full-text available
The commensal microbiota has a high impact on health and disease by modulating the development and homeostasis of host immune system. Immune cells are involved in virtually every aspect of the wound repair process; however, the impact of commensal microbiota on skin wound healing is largely unknown. In this study, we evaluated the influence of commensal microbiota on tissue repair of excisional skin wounds by using germ-free (GF) Swiss mice. We observed that macroscopic wound closure rate is accelerated in the absence of commensal microbiota. Accordantly, histologically assessed wound epithelization was accelerated in GF in comparison with conventional (CV) Swiss mice. The wounds of GF mice presented a significant decrease in neutrophil accumulation and an increase in mast cell and macrophage infiltration into wounds. Interestingly, alternatively activated healing macrophage-related genes were highly expressed in the wound tissue of GF mice. Moreover, levels of the anti-inflammatory cytokine IL-10, the angiogenic growth factor VEGF and angiogenesis were higher in the wound tissue of those mice. Conversely, scarring and levels of the profibrogenic factor TGF-β1 were greatly reduced in GF mice wounded skin when compared with CV mice. Of note, conventionalization of GF mice with CV microbiota restored wound closure rate, neutrophil and macrophage accumulation, cytokine production, and scarring to the same extent as CV mice. Overall, our findings suggest that, in the absence of any contact with microbiota, skin wound healing is accelerated and scarless, partially because of reduced accumulation of neutrophils, increased accumulation of alternatively activated healing macrophages, and better angiogenesis at wound sites.
Article
Full-text available
The host immune response plays a critical role not only in protection from human leishmaniasis, but also in promoting disease severity. Although candidate gene approaches in mouse models of leishmaniasis have been extremely informative, a global understanding of the immune pathways active in lesions from human patients is lacking. To address this issue, genome-wide transcriptional profiling of Leishmania braziliensis-infected cutaneous lesions and normal skin controls was carried out. A signature of the L. braziliensis skin lesion was defined that includes over 2,000 differentially regulated genes. Pathway-level analysis of this transcriptional response revealed key biological pathways present in cutaneous lesions, generating a testable 'metapathway' model of immunopathology, and providing new insights for treatment of human leishmaniasis.Journal of Investigative Dermatology accepted article preview online, 18 July 2014; doi:10.1038/jid.2014.305.
Article
Full-text available
While landmark studies have shown that microbiota activate and educate host immunity, how immune systems shape microbiomes and contribute to disease is incompletely characterized. Primary immunodeficiency (PID) patients suffer recurrent microbial infections, providing a unique opportunity to address this issue. To investigate the potential influence of host immunity on the skin microbiome, we examined skin microbiomes in patients with rare monogenic PIDs: hyper-IgE (STAT3-deficient), Wiskott-Aldrich, and dedicator of cytokinesis 8 syndromes. While specific immunologic defects differ, a shared hallmark is atopic dermatitis (AD)-like eczema. We compared bacterial and fungal skin microbiomes (41 PID, 13 AD, 49 healthy controls) at four clinically relevant sites representing the major skin microenvironments. PID skin displayed increased ecological permissiveness with altered population structures, decreased site specificity and temporal stability, and colonization with microbial species not observed in controls, including Clostridium species and Serratia marcescens. Elevated fungal diversity and increased representation of opportunistic fungi (Candida, Aspergillus) supported increased PID skin permissiveness, suggesting that skin may serve as a reservoir for the recurrent fungal infections observed in these patients. The overarching theme of increased ecological permissiveness in PID skin was counterbalanced by the maintenance of a phylum barrier in which colonization remained restricted to typical human-associated phyla. Clinical parameters, including markers of disease severity, were positively correlated with prevalence of Staphylococcus, Corynebacterium, and other less abundant taxa. This study examines differences in microbial colonization and community stability in PID skin and informs our understanding of host-microbiome interactions, suggesting a bidirectional dialogue between skin commensals and the host organism.
Article
Full-text available
One of the hallmarks of adaptive immunity is the development of a long-term pathogen specific memory response. While persistent memory T cells certainly impact the immune response during a secondary challenge, their role in unrelated infections is less clear. To address this issue, we utilized lymphocytic choriomeningitis virus (LCMV) and Listeria monocytogenes immune mice to investigate whether bystander memory T cells influence Leishmania major infection. Despite similar parasite burdens, LCMV and Listeria immune mice exhibited a significant increase in leishmanial lesion size compared to mice infected with L. major alone. This increased lesion size was due to a severe inflammatory response, consisting not only of monocytes and neutrophils, but also significantly more CD8 T cells. Many of the CD8 T cells were LCMV specific and expressed gzmB and NKG2D, but unexpectedly expressed very little IFN-γ. Moreover, if CD8 T cells were depleted in LCMV immune mice prior to challenge with L. major, the increase in lesion size was lost. Strikingly, treating with NKG2D blocking antibodies abrogated the increased immunopathology observed in LCMV immune mice, showing that NKG2D engagement on LCMV specific memory CD8 T cells was required for the observed phenotype. These results indicate that bystander memory CD8 T cells can participate in an unrelated immune response and induce immunopathology through an NKG2D dependent mechanism without providing increased protection.
Article
Full-text available
Understanding gut microbiota alterations associated with HIV infection and factors that drive these alterations may help explain gut-linked diseases prevalent with HIV. 16S rRNA sequencing of feces from HIV-infected individuals revealed that HIV infection is associated with highly characteristic gut community changes, and antiretroviral therapy does not consistently restore the microbiota to an HIV-negative state. Despite the chronic gut inflammation characteristic of HIV infection, the associated microbiota showed limited similarity with other inflammatory states and instead showed increased, rather than decreased, diversity. Meta-analysis revealed that the microbiota of HIV-infected individuals in the U.S. was most similar to a Prevotella-rich community composition typically observed in healthy individuals in agrarian cultures of Malawi and Venezuela and related to that of U.S. individuals with carbohydrate-rich, protein- and fat-poor diets. By evaluating innate and adaptive immune responses to lysates from bacteria that differ with HIV, we explore the functional drivers of these compositional differences.
Article
Full-text available
Disease progression in response to infection can be strongly influenced by both pathogen burden and infection-induced immunopathology. While current therapeutics focus on augmenting protective immune responses, identifying therapeutics that reduce infection-induced immunopathology are clearly warranted. Despite the apparent protective role for murine CD8+ T cells following infection with the intracellular parasite Leishmania, CD8+ T cells have been paradoxically linked to immunopathological responses in human cutaneous leishmaniasis. Transcriptome analysis of lesions from Leishmania braziliensis patients revealed that genes associated with the cytolytic pathway are highly expressed and CD8+ T cells from lesions exhibited a cytolytic phenotype. To determine if CD8+ T cells play a causal role in disease, we turned to a murine model. These studies revealed that disease progression and metastasis in L. braziliensis infected mice was independent of parasite burden and was instead directly associated with the presence of CD8+ T cells. In mice with severe pathology, we visualized CD8+ T cell degranulation and lysis of L. braziliensis infected cells. Finally, in contrast to wild-type CD8+ T cells, perforin-deficient cells failed to induce disease. Thus, we show for the first time that cytolytic CD8+ T cells mediate immunopathology and drive the development of metastatic lesions in cutaneous leishmaniasis.
Article
Full-text available
Rapid advances in sequencing technology have changed the experimental landscape of microbial ecology. In the last 10 years the field has moved from sequencing hundreds of 16S rRNA gene fragments per study using clone libraries to the sequencing of millions of fragments per study using next generation sequencing technologies from 454 and Illumina. As these technologies advance it is critical to assess the strengths, weaknesses and overall suitability of these platforms for the interrogation of microbial communities. Here we present an improved method for sequencing variable regions within the 16S rRNA gene using Illumina's MiSeq platform, which is currently capable of producing paired 250-nt reads. We evaluated three overlapping regions of the 16S rRNA gene that vary in their length (i.e. V34, V4, and V45) by re-sequencing a mock community and natural samples from human feces, mouse feces, and soil. By titrating the concentration of 16S rRNA gene amplicons applied to the flow cell and using a quality score-based approach to correct discrepancies between reads used to construct contigs, we were able to reduce error rates by as much as two orders of magnitude. Finally, we re-processed samples from a previous study to demonstrate that large numbers of samples could be multiplexed and sequenced in parallel with shotgun metagenomes. These analyses demonstrate that our approach can provide data that are at least as good as that generated by the 454 platform while providing considerably higher sequencing coverage for a fraction of the cost.
Article
Full-text available
Leishmaniasis, resulting from infection with the protozoan parasite Leishmania, consists of a wide spectrum of clinical manifestations, from healing cutaneous lesions to fatal visceral infections. A particularly severe form of cutaneous leishmaniasis, termed mucosal leishmaniasis, exhibits decreased IL-10 levels and an exaggerated inflammatory response that perpetuates the disease. Using a mouse model of leishmaniasis, we investigated what cytokines contribute to increased pathology when IL-10-mediated regulation is absent. Leishmania major infected C57BL/6 mice lacking IL-10 regulation developed larger lesions than controls, but fewer parasites. Both IFN-γ and IL-17 levels were substantially elevated in mice lacking the capacity to respond to IL-10. IFN-γ promoted an increased infiltration of monocytes, while IL-17 contributed to an increase in neutrophils. Surprisingly, however, we found that IFN-γ did not contribute to increased pathology, but instead regulated the IL-17 response. Thus, blocking IFN-γ led to a significant increase in IL-17, neutrophils and disease. Similarly, the production of IL-17 by cells from leishmaniasis patients was also regulated by IL-10 and IFN-γ. Additional studies found that the IL-1 receptor was required for both the IL-17 response and increased pathology. Therefore, we propose that regulating IL-17, possibly by downregulating IL-1β, may be a useful approach for controlling immunopathology in leishmaniasis.
Article
Full-text available
There is a need for a simple and efficacious treatment for cutaneous leishmaniasis with an acceptable side-effect profile. We conducted a randomized, vehicle-controlled phase 3 trial of topical treatments containing 15% paromomycin, with and without 0.5% gentamicin, for cutaneous leishmaniasis caused by Leishmania major in Tunisia. We randomly assigned 375 patients with one to five ulcerative lesions from cutaneous leishmaniasis to receive a cream containing 15% paromomycin-0.5% gentamicin (called WR 279,396), 15% paromomycin alone, or vehicle control (with the same base as the other two creams but containing neither paromomycin nor gentamicin). Each lesion was treated once daily for 20 days. The primary end point was the cure of the index lesion. Cure was defined as at least 50% reduction in the size of the index lesion by 42 days, complete reepithelialization by 98 days, and absence of relapse by the end of the trial (168 days). Any withdrawal from the trial was considered a treatment failure. The rate of cure of the index lesion was 81% (95% confidence interval [CI], 73 to 87) for paromomycin-gentamicin, 82% (95% CI, 74 to 87) for paromomycin alone, and 58% (95% CI, 50 to 67) for vehicle control (P<0.001 for each treatment group vs. the vehicle-control group). Cure of the index lesion was accompanied by cure of all other lesions except in five patients, one in each of the paromomycin groups and three in the vehicle-control group. Mild-to-moderate application-site reactions were more frequent in the paromomycin groups than in the vehicle-control group. This trial provides evidence of the efficacy of paromomycin-gentamicin and paromomycin alone for ulcerative L. major disease. (Funded by the Department of the Army; ClinicalTrials.gov number, NCT00606580.).
Article
Full-text available
A protective or deleterious role of CD8(+)T cells in human cutaneous leishmaniasis (CL) has been debated. The present report explores the participation of CD8(+)T cells in disease pathogenesis as well as in the parasite killing. CD8(+) T cells accumulated in CL lesions as suggested by a higher frequency of CD8(+)CD45RO(+)T cells and CD8(+)CLA(+)T cells compared to PBMC. Upon L. braziliensis-restimulation, most of CD8(+)T cells from the lesion expressed cytolytic markers, CD107a and granzyme B. Granzyme B expression in CL lesions positively correlated with lesion size and percentage of TUNEL-positive cells. We also observed a significant higher percentage of TUNEL-positive cells and granzyme B expression in the biopsies of patients showing a more intense necrotic process. Furthermore, co-culture of infected macrophages and CD8(+)T lymphocytes resulted in release of granzyme B and the use of granzyme B inhibitor, as well as z-VAD, Fas:Fc or anti-IFN-γ had no effect upon parasite killing. However, co-culture of infected macrophages with CD4(+)T cells strongly increased parasite killing, which was completely reversed by anti-IFN-γ. Our results reveal a dichotomy in human cutaneous leishmaniasis: CD8(+) Granzyme B(+)T cells mediate tissue injury whereas CD4(+) IFN-γ(+)T cells mediate parasite killing.Journal of Investigative Dermatology accepted article preview online, 15 January 2013; doi:10.1038/jid.2013.4.
Article
Full-text available
Skin Specifics Much of the recent attention paid to the trillions of bacteria that colonize our bodies has been given to the bacteria that reside in the gut. Naik et al. (p. 1115 , published online 26 July) report that colonization of the skin with commensal bacteria is important for tuning effector T cell responses in the skin and for protective immunity against cutaneous infection with the parasite Leishmania major in mice. In contrast, selective depletion of the gut microbiota, which plays an important role in modulating immune responses in the gut, had no impact on T cell responses in the skin.
Article
Full-text available
Leishmania mexicana can cause both localized (LCL) and diffuse (DCL) cutaneous leishmaniasis, yet little is known about factors regulating disease severity in these patients. We analyzed if the disease was associated with single nucleotide polymorphisms (SNPs) in IL-1β (-511), CXCL8 (-251) and/or the inhibitor IL-1RA (+2018) in 58 Mexican mestizo patients with LCL, 6 with DCL and 123 control cases. Additionally, we analyzed the in vitro production of IL-1β by monocytes, the expression of this cytokine in sera of these patients, as well as the tissue distribution of IL-1β and the number of parasites in lesions of LCL and DCL patients. Our results show a significant difference in the distribution of IL-1β (-511 C/T) genotypes between patients and controls (heterozygous OR), with respect to the reference group CC, which was estimated with a value of 3.23, 95% CI = (1.2, 8.7) and p-value = 0.0167), indicating that IL-1β (-511 C/T) represents a variable influencing the risk to develop the disease in patients infected with Leishmania mexicana. Additionally, an increased in vitro production of IL-1β by monocytes and an increased serum expression of the cytokine correlated with the severity of the disease, since it was significantly higher in DCL patients heavily infected with Leishmania mexicana. The distribution of IL-1β in lesions also varied according to the number of parasites harbored in the tissues: in heavily infected LCL patients and in all DCL patients, the cytokine was scattered diffusely throughout the lesion. In contrast, in LCL patients with lower numbers of parasites in the lesions, IL-1β was confined to the cells. These data suggest that IL-1β possibly is a key player determining the severity of the disease in DCL patients. The analysis of polymorphisms in CXCL8 and IL-1RA showed no differences between patients with different disease severities or between patients and controls.
Article
Full-text available
Atopic dermatitis (AD) has long been associated with Staphylococcus aureus skin colonization or infection and is typically managed with regimens that include antimicrobial therapies. However, the role of microbial communities in the pathogenesis of AD is incompletely characterized. To assess the relationship between skin microbiota and disease progression, 16S ribosomal RNA bacterial gene sequencing was performed on DNA obtained directly from serial skin sampling of children with AD. The composition of bacterial communities was analyzed during AD disease states to identify characteristics associated with AD flares and improvement post-treatment. We found that microbial community structures at sites of disease predilection were dramatically different in AD patients compared with controls. Microbial diversity during AD flares was dependent on the presence or absence of recent AD treatments, with even intermittent treatment linked to greater bacterial diversity than no recent treatment. Treatment-associated changes in skin bacterial diversity suggest that AD treatments diversify skin bacteria preceding improvements in disease activity. In AD, the proportion of Staphylococcus sequences, particularly S. aureus, was greater during disease flares than at baseline or post-treatment, and correlated with worsened disease severity. Representation of the skin commensal S. epidermidis also significantly increased during flares. Increases in Streptococcus, Propionibacterium, and Corynebacterium species were observed following therapy. These findings reveal linkages between microbial communities and inflammatory diseases such as AD, and demonstrate that as compared with culture-based studies, higher resolution examination of microbiota associated with human disease provides novel insights into global shifts of bacteria relevant to disease progression and treatment.
Article
Full-text available
Glucantime is regarded as the first-line treatment of cutaneous leishmaniasis (CL); however, failure to treatment is a problem in many cases. The aim was to evaluate the therapeutic effect of glucantime in CL complicated with secondary bacterial infection compared to uncomplicated lesions. This experimental study was performed in Skin Diseases and Leishmaniasis Research Center, Isfahan, Iran. A total of 161 patients enrolled in the study had CL confirmed by positive smear of lesions. All the patients were treated with systemic glucantime for 3 weeks and followed for 2 months. Response to treatment was defined as loss of infiltration, reepithelization, and negative smear. Depending on the results of bacterial cultures, the lesions were divided into two groups and the efficacy of glucantime was compared. A total of 123 patients (76.4%) were negative, and 38 patients (23.6%) were positive for secondary bacterial infection. In groups with negative bacterial culture response to treatment was 65% (80 patients) and in the other positive group, it was 31.6% (12 patients), with a difference (χ(2) = 13.77, P < 0.01). Therapeutic effect of glucantime showed a decrease in CL lesions with secondary bacterial infection. Therefore, in the cases of unresponsiveness to treatment, the lesions should be evaluated for bacterial infection, before repeating the treatment.
Article
Full-text available
This study aimed to investigate the activity of a combination of topical paromomycin gel and oral miltefosine for the treatment of experimental cutaneous leishmaniasis caused by Leishmania (Leishmania) amazonensis. The efficacy of the combination, evaluated by measuring lesion size and parasite burden in the skin and spleen, was assessed in BALB/c mice infected by L. (L.) amazonensis. The miltefosine was administered orally at 10 mg/kg of body weight/day for 10 days, while 10% paromomycin gel was applied topically twice a day for 20 days. Treatment of the experimentally infected animals with a topical paromomycin-oral miltefosine combination induced a statistically significant reduction in lesion size and parasite burden in the skin and spleen, with complete healing of ulcers, compared with those treated with a placebo group. A combination of topical paromomycin gel and oral miltefosine provided enhanced efficacy in the treatment of L. (L.) amazonensis-infected mice, showing activity higher than that observed for the monotherapeutic regimens.
Article
Full-text available
Diabetics frequently suffer from chronic, nonhealing wounds. Although bacterial colonization and/or infection are generally acknowledged to negatively impact wound healing, the precise relationship between the microbial community and impaired wound healing remains unclear. Because the host cutaneous defense response is proposed to play a key role in modulating microbial colonization, we longitudinally examined the diabetic wound microbiome in tandem with host tissue gene expression. By sequencing 16S ribosomal RNA genes, we show that a longitudinal selective shift in wound microbiota coincides with impaired healing in diabetic mice (Lepr(db/db); db/db). We demonstrate a parallel shift in longitudinal gene expression that occurs in a cluster of genes related to the immune response. Further, we establish a correlation between relative abundance of Staphylococcus spp. and the expression of cutaneous defense response genes. Our data demonstrate that integrating two types of global datasets lends a better understanding to the dynamics governing host-microbe interactions.
Article
Full-text available
An extensive portion of the healthcare budget is allocated to chronic human infection. Chronic wounds in particular are a major contributor to this financial burden. Little is known about the types of bacteria which may contribute to the chronicity, biofilm and overall bioburden of the wound itself. In this study we compare the bacteriology of wounds and associated intact skin. Wound and paired intact skin swabs (from a contralateral location) were collected. The bacterial diversity was determined using bacterial Tag-encoded FLX amplicon pyrosequencing (bTEFAP). Diversity analysis showed intact skin to be significantly more diverse than wounds on both the species and genus levels (3% and 5% divergence). Furthermore, wounds show heightened levels of anaerobic bacteria, like Peptoniphilus, Finegoldia, and Anaerococcus, and other detrimental genera such as Corynebacterium and Staphylococcus. Although some of these and other bacterial genera were found to be common between intact skin and wounds, notable opportunistic wound pathogens were found at lower levels in intact skin. Principal Component Analysis demonstrated a clear separability of the two groups. The findings of the study not only greatly support the hypothesis of differing bacterial composition of intact skin and wounds, but also contribute additional insight into the ecology of skin and wound microflora. The increased diversity and lowered levels of opportunistic pathogens found in skin make the system highly distinguishable from wounds.