Rossana C. N. Melo

Federal University of Juiz de Fora

A key function of human eosinophils is to secrete cytokines, chemokines and cationic proteins, trafficking, and releasing these mediators for roles in inflammation and other immune responses. Eosinophil activation leads to secretion of pre-synthesized granule-stored mediators through different mechanisms, but the ability of eosinophils to secrete e...

Eosinophil activation leads to secretion of presynthesized, granule-stored mediators that determine the course of allergic, inflammatory, and immunoregulatory responses. CD63, a member of the transmembrane-4 glycoprotein superfamily (tetraspanins) and present on the limiting membranes of eosinophil-specific (secretory) granules, is considered a pot...

Precise immunolocalization of proteins within a cell is central to understanding cell processes and functions such as intracellular trafficking and secretion of molecules during immune responses. Here we describe a protocol for ultrastructural detection of proteins in leukocytes. The method uses a pre-embedding approach (immunolabeling before stand...

Phagocytosis of invading microorganisms by specialized cells such as macrophages and neutrophils is a key component of the innate immune response. These cells capture and engulf pathogens and subsequently destroy them in intracellular vacuoles-the phagosomes. Pathogen phagocytosis and progression and maturation of pathogen-containing phagosomes, a...

Etnopharmacological relevance: Traditional uses of Annona muricata L. (soursop) include treatment for cancer, fungal infections, and inflammatory diseases. Its phytoconstituents, mainly acetogenins and alkaloids, are associated with therapeutic activity and clinical application is currently under investigation. However, the application of phytothe...

Uncontrolled airway mucus is associated with diverse diseases. We hypothesized that the physical characteristics of infiltrating granulocytes themselves affect the clinical properties of mucus. Surgically obtained nasal mucus from patients with eosinophilic chronic rhinosinusitis (ECRS) and neutrophil-dominant non-eosinophilic chronic rhinosinusiti...

Eosinophils are remarkably recruited during schistosomiasis mansoni, one of the most common parasitic diseases worldwide. These cells actively migrate and accumulate at sites of granulomatous inflammation termed granulomas, the main pathological feature of this disease. Eosinophils colonize granulomas as a robust cell population and establish compl...

Etnopharmacological relevance Annona muricata L. (soursop) is traditionally used in the treatment of inflammatory diseases, cancer, and infections caused by fungi. The therapeutic activity explored by its medicinal use is generally associated with its phytoconstituents, such as acetogenins and alkaloids. However, its potential antifungal bioactivit...

Galectin-10 is a member of the lectin family and one of the most abundant cytoplasmic proteins in human eosinophils. Except for some myeloid leukemia cells, basophils, and minor T cell populations, galectin-10 is exclusively present in eosinophils in the human body. Galectin-10 forms Charcot–Leyden crystals, which are observed in various eosinophil...

The ability of freshwater bacteria to secrete extracellular vesicles (EVs) upon interaction with viruses remains to be established. Here, we investigated for the first time if freshwater virus‐infected bacteria release EVs in both natural ecosystems and virus‐like particles (VLPs)‐enriched cultures. We performed a systematic study using transmissio...

Eosinophilic diseases, also termed eosinophil-associated diseases (EADs), are characterized by eosinophil-rich inflammatory infiltrates and extensive eosinophil degranulation with clinically relevant organ pathology. Recent evidence shows that eosinophil cytolytic degranulation, that is, the release of intact, membrane-delimited granules that arise...

Visceral leishmaniasis (VL) is the most severe clinical form of leishmaniasis, being fatal if untreated. In search of a more effective treatment for VL, one of the main strategies is the development and screening of new antileishmanial compounds. Here, we reported the synthesis of seven new acetyl functionalized 1,2,3-triazolium salts, together wit...

Host immune responses contribute to dengue's pathogenesis and severity, yet the possibility that failure in endogenous inflammation resolution pathways could characterise the disease has not been contemplated. The pro-resolving protein Annexin A1 (AnxA1) is known to counterbalance overexuberant inflammation and mast cell (MC) activation. We hypothe...

In 2015, Brazil reported an outbreak identified as Zika virus (ZIKV) infection associated with congenital abnormalities. To date, a total of 86 countries and territories have described evidence of Zika infection and recently the appearance of the African ZIKV lineage in Brazil highlights the risk of a new epidemic. The spectrum of ZIKV infection-in...

Mitochondria are multifunctional organelles of which ultrastructure is tightly linked to cell physiology. Accumulating evidence shows that mitochondrial remodeling has an impact on immune responses, but our current understanding of the mitochondrial architecture, interactions, and morphological changes in immune cells, mainly in eosinophils, is sti...

Mice models have contributed greatly to our understanding of the mechanisms underlying eosinophil-associated diseases (EADs) and other human diseases. These models include not only wild-type mice but also micewith genetically manipulated numbers of eosinophils (increased or decreased) as well as mice with added, modified, or deleted specific genes...

Eosinophils are remarkable secretory cells able to release a large and varied collection of immune mediators upon cell activation. Ultrastructural evidence of eosinophil activation encompasses a multitude of events such as substantial morphological alterations of specific (secretory) granules, including a significant increase in the numbers of gran...

Eosinophils can be prominent in virtually any tissue during inflammatory responses increasing in number as a constituent of mixed inflammation or being the predominant or even the only cell found in inflammatory infiltrates. Peripheral blood and tissue eosinophilia can occur in patients with varied allergic and inflammatory diseases, as well as div...

While conventional transmission electron microscopy (TEM) has been used to unveil ultrastructural features of eosinophils, such as distinct secretory patterns, TEM combined with molecular detection methods has been applied for precise localization of proteins to intracellular compartments. Visualization of specific proteins at the nanoscale level i...

The life cycle of the eosinophil is divided into bone marrow, blood, and tissue phases. Like other hematopoietic lineages, eosinophils are derived from common hematopoietic stem cells and multilineage progenitors in the bone marrow. Eosinophil differentiation from multipotent progenitor cells leads to the formation of eosinophil progenitors (EoPs)...

The purpose of this chapter is to describe the ultrastructural architecture of mature human eosinophils as observed in normal conditions. These cells are ~12–15 μm in diameter and, like other granulocytes, are characterized by a segmented nucleus usually seen as a bilobed organelle, large secretory granules (specific granules) in the cytoplasm, and...

The role of eosinophils markedly relies on their ability to release their immune compounds, a process collectively referred to as degranulation. Many immune mediators are stored as preformed pools within eosinophil secretory (specific) granules. As with other nucleated cells, de novo synthesis of cytokines and other mediators within the endoplasmic...

The process of cell death is associated with multiple human diseases and is also considered an essential event for normal development and homeostasis. Cell death manifests with morphological changes. From a morphological point of view, cell death depicts fundamentally a cytolytic (also termed necrotic) or a noncytolytic (apoptotic) morphology. Both...

Host immune responses contribute to dengue's pathogenesis and severity, yet the possibility that failure in endogenous inflammation resolution pathways could characterise the disease has not been contemplated. The pro-resolving protein Annexin A1 (AnxA1) is known to counterbalance overexuberant inflammation and mast cell (MC) activation. We hypothe...

The battery of antifungals available to treat infections caused by Candida albicans is limited and can lead to adverse effects. Treatment of these infections continues to be a challenge mainly because of the Candida resistance to multiple antifungals. The aim of this work was to investigate the antifungal activity of Mitracarpus frigidus (Willd. Ex...

Spilanthol is a bioactive alkylamide from the native Amazon plant species, Acmella oleracea. However, antifungal activities of spilanthol and its application to the therapeutic treatment of candidiasis remains to be explored. This study sought to evaluate the in vitro and in vivo antifungal activity of spilanthol previously isolated from A. olerace...

New strategies that enable fast and accurate visualization of Candida biofilms are necessary to better study their structure and response to antifungals agents. Here, we applied whole slide imaging (WSI) to study biofilm formation of Candida species. Three relevant biofilm-forming Candida species (C. albicans ATCC 10231, C. glabrata ATCC 2001, and...

Objective Eosinophils are tissue‐dwelling immune cells. Accumulating evidence indicates that a type of cell death termed ETosis is an important cell fate involved in the pathophysiology of inflammatory diseases. Although the critical role of eosinophils, in eosinophilic granulomatosis with polyangiitis (EGPA, formerly Churg‐Strauss syndrome) is wel...

Schistosomiasis, a neglected parasitic tropical disease that has plagued humans for centuries, remains a major public health burden. A primary challenge to understanding schistosomiasis is deciphering the most remarkable pathological feature of this disease, the granuloma – a highly dynamic and self‐organized structure formed by both host and paras...

Eosinophils are granulocytes classically involved in allergic diseases and in the host immune responses to helminths, fungi, bacteria and viruses. The release of extracellular DNA traps by leukocytes is an important mechanism of the innate immune response to pathogens in various infectious conditions, including fungal infections. Aspergillus fumiga...

Matrix-assisted laser desorption/ionization (MALDI) has evolved to become a well-established technique during the last decades. Because of matrix peak interference in the low molecular-weight region, however, new matrices are often studied with the purpose of improving the spectral quality under m/z 500. Herein, we present the substance 2,4,5,7-tet...

In 2015, Brazil reported an outbreak identified as Zika virus (ZIKV) infection associated with congenital abnormalities. To date, a total of 86 countries and territories have described evidence of Zika infection and recently the appearance of the African ZIKV lineage in Brazil highlights the risk of a new epidemic. The spectrum of ZIKV infection-in...

Abstract: Viruses cause various diseases in humans through vector-borne (e.g., Zika and dengue fever), airborne (e.g., measles) and water-borne (e.g., hepatitis) transmission, as well as direct physical contact (e.g., AIDS and herpes). Recently, the new coronavirus (SARS-CoV-2) pandemic has triggered the greatest global health crisis in a century....

The purpose of this study was to develop tea tree oil (TTO)-loaded chitosan-poly(ε-caprolactone) core-shell nanocapsules (NC-TTO-Ch) aiming the topical acne treatment. TTO was analyzed by gas chromatography-mass spectrometry, and nanocapsules were characterized regarding mean particle size (Z-average), polydispersity index (PdI), zeta potential (ZP...

Congenital Zika Syndrome was first described due to increased incidence of congenital abnormalities associated with Zika virus (ZIKV) infection. Since the eye develops as part of the embryo central nervous system (CNS) structure, it becomes a specialized compartment able to display symptoms of neurodegenerative diseases and have been proposed as a...

Candida tropicalis is one the most relevant biofilm-forming fungal species increasingly associated with invasive mucosal candidiasis worldwide. The amplified antifungal resistance supports the necessity for more effective and less toxic treatment, including the use of plant-derived natural products. Scopoletin, a natural coumarin, has shown antifun...

The Charcot-Leyden crystal protein (CLC-P), a constituent of human and not mouse eosinophils, is one of the most abundant proteins within human eosinophils. It has a propensity to form crystalline structures, Charcot-Leyden crystals, which are hallmarks in their distinctive extracellular crystalline forms as markers of eosinophilic inflammation. Th...

New strategies that enable fast and accurate visualization of Candida biofilms are necessary to better study their structure and response to antifungals agents. Here, we applied whole slide imaging (WSI) to study biofilm formation of Candida species. Three relevant biofilm-forming Candida species ( C. albicans ATCC 10231 , C. glabrata ATCC 2001, an...

A predominant protein of human eosinophils is galectin-10 (Gal-10), also known as CharcotLeyden crystal protein (CLC-P) because of its remarkable ability to form Charcot-Leyden crystals (CLCs), which are frequently found in tissues from patients with eosinophilic disorders. CLCP/Gal-10 is highly expressed in human eosinophils and considered a bioma...

Neutrophils are leukocytes that are capable of eliminating both intra- and extracellular pathogens by mechanisms such as phagocytosis, degranulation and release of neutrophil extracellular traps (NET). Histoplasma capsulatum var. capsulatum (H. capsulatum) is a dimorphic fungus with a global distribution that causes histoplasmosis, a disease that i...

Histological analysis of hepatic tissue specimens is essential for evaluating the pathology of several liver disorders such as chronic liver diseases, hepatocellular carcinomas, liver steatosis, and infectious liver diseases. Manual examination of histological slides on the microscope is a classically used method to study these disorders. However,...

Salmonella spp. are a group of bacteria important to salmonellosis, a common infection frequently related to human contamination. In this context, new strategies to prevent or control these microorganisms are considered to be of global importance. The Mitracarpus frigidus aerial parts extracted by methanol (MFM) have several biological activities i...

Importance: Non-invasive techniques for retrieving ocular surface cells from babies infected by zika virus (ZIKV) during the gestational period remain to be determined. Objectives: The aim of this study was to describe an optimized impression cytology method for the isolation of viable cells from Zika infected babies with and without Congenital...

Trypanosoma cruzi causes Chagas disease, a neglected illness that affects millions of people worldwide, especially in Latin America. The balance between biochemical pathways triggered by the parasite and host cells response will ultimately define the progression of a life-threatening disease, justifying the efforts to understand cellular mechanisms...

IMPORTANCE Ocular complications in infants with Congenital Zika Syndrome (CZS) have been reported. However, the molecular mechanisms underlying of eye dysfunctions are presently unknown. OBJECTIVE A method (termed Cellular Imprinting Proteomics, CImP) for the identification and quantification of the ocular surface proteome using a minimally invasi...

Eosinophils and neutrophils are critical for host defense, yet gaps in understanding how granulocytes differentiate from hematopoietic stem cells (HSCs) into mature effectors remain. The pseudokinase tribbles homolog 1 (Trib1) is an important regulator of granulocytes; knockout mice lack eosinophils and have increased neutrophils. However, how Trib...

IMPORTANCE Noninvasive techniques for obtaining ocular surface cells (neuroepithelial) from babies with Congenital Zika Syndrome CZS - resulting from infection by zika virus (ZIKV) during gestational period (malformations include ocular abnormalities and microcephaly) - remain to be determined. OBJECTIVES The aim of this study was to describe an o...

Eosinophils have been long associated with helminthic infections, although their functions in these diseases remain unclear. During schistosomiasis caused by the trematode Schistosoma mansoni, eosinophils are specifically recruited and migrate to sites of granulomatous responses where they degranulate. However, little is known about the mechanisms...

Candida species are opportunistic pathogens associated with some important clinical infections such as vulvovaginal candidiasis (VVC). Nowadays, candidiasis is a public health problem that is aggravated by inefficiency of the traditionally used antifungal agents. The aim of the work was to evaluate the in vitro and in vivo antifungal activity of M....

Protein crystallization in human tissue rarely occurs. Charcot-Leyden crystals (CLCs) were described in various eosinophilic diseases over 150 years ago, but our understanding of CLC formation still remains limited. In this study, we demonstrate that CLCs observed in varied inflamed human tissues are closely associated with eosinophil cell-free gra...

Human eosinophils release numerous cytokines that are pre-synthesized and stored within their cytoplasmic-specific (secretory) granules. For example, high levels of interferon-gamma (IFN-γ) are constitutively expressed in these cells, but the intracellular compartments involved in the transport and release of this cytokine remain to be established....

Psychorubrin, a natural pyranonaphthoquinone found in different plants, has become an interesting compound in the search for new antimicrobial therapeutic agents. Here, we investigated the potential antagonistic activity of psychorubrin against planktonic and biofilm bacteria. First, psychorubrin was tested against several Gram-positive and Gram-ne...

Secretion of membrane-limited vesicles, collectively termed extracellular vesicles (EVs), is an important biological process of both eukaryotic and prokaryotic cells. This process has been observed in bacteria, but remains to be better characterized at high resolution in cyanobacteria. In the present work, we address the release of EVs by Cylindros...

Eosinophil secretory (specific) granules have a unique morphology and are both a morphologic hallmark of eosinophils and fundamental to eosinophil-mediated responses. Eosinophil mediators with multiple functional activities are presynthesized and stored within these granules, poised for very rapid, stimulus-induced secretion. The structural organiz...

Annona muricata has become an interesting subject in the search for new therapeutic agents. We investigated the bacterial mode of action of the methanolic extract of A. muricata leaves (AML). AML extract was tested against several bacteria strains by broth microdilution susceptibility method. The bacterial killing assay, bacterial abundance and mem...

The pathology of schistosomiasis mansoni, a neglected tropical disease of great clinical and socioeconomic importance, results from the parasite eggs that become trapped in host tissues, particularly in the liver and intestines. Continuous antigenic stimulation from these eggs leads to recruitment of inflammatory cells to the sites of infection wit...

Representative histological sections of uninfected organs from Nectomys squamipes and Swiss mice. Note the general morphology and preserved architecture of the liver (A, B), small intestines (C, D) and large intestines (E, F) of N. squamipes (A, C, E) and Swiss mouse (B, D, F). Bar = 100 μm (A, B); 150 μm (C, F); 200 μm (D); 120 μm (E). Liver and i...

Comparison between granuloma types in target organs from natural (Nectomys squamipes) and experimental (Swiss mice—acute and chronic phase) infections with Schistosoma mansoni. (PDF)

Background: Eosinophils mediate the immune response in different infection conditions. The release of extracellular DNA traps (ETs) by leukocytes has been described as an innate immune response mechanism that is relevant in many disorders including fungal diseases. Different stimuli induce human eosinophil ETs (EETs) release. Aspergillus fumigatus...

This study aimed to further investigate the cytotoxicity against tumor cell lines and several bacterial strains of Annona squamosa and its mode of action. Methanol extracts of A. squamosa leaves (ASL) and seeds (ASS) were used. ASL showed significant antibacterial activity against S. aureus, K. pneumoniae and E. faecalis with MIC values of 78, 78 a...

Study question: Can all types of testicular germ cells be accurately identified by microscopy techniques and unambiguously distributed in stages of the human seminiferous epithelium cycle (SEC)? Summary answer: By using a high-resolution light microscopy (HRLM) method, which enables an improved visualization of germ cell morphological features,...

Eosinophils are multifunctional cells of the innate immune system linked to allergic inflammation. Asthmatics were more likely to be hospitalized but less likely to suffer severe morbidity and mortality during the 2009 influenza pandemic. These epidemiologic findings were recapitulated in a mouse model of fungal asthma wherein infection during heig...

Bacterial cell death has key functional implications in bacterial dynamics and biogeochemical cycles in aquatic ecosystems. In this review, we highlight the use of light microscopy and transmission electron microscopy (TEM) to study cell viability and events of cell death in bacteria from freshwater ecosystems. First, we focus on the applications o...

Schistosomiasis is a neglected tropical disease of a significant public health impact. The water rat Nectomys squamipes is one of the most important non-human hosts in the schisto-somiasis mansoni transmission in Brazil, being considered a wild reservoir. Cellular mechanisms that contribute to the physiological adaptation of this rodent to the Schi...

Quantitative analyses of LD numbers in the hepatic tissue from naturally and experimentally infected animals. Liver fragments were fixed in buffered paraformaldehyde and stained with ORO. LD quantifications were performed in a slide scanner using Pannoramic Viewer and Histoquant softwares. A total of 1,500,000 μm2 of tissue area was evaluated per a...

Secretion of membrane vesicles is an important biological process of both eukaryotic and prokaryotic cells. This process has been characterized in pathogenic bacteria, but is less clear in non-pathogenic bacteria from aquatic ecosystems. Here, we investigated, for the first time, the process of formation of outer membranes vesicles (OMVs), nanoscal...

Lipid droplets were long considered to be simple storage structures, but they have recently been shown to be dynamic organelles involved in diverse biological processes, including emerging roles in innate immunity. Various intracellular pathogens, including viruses, bacteria and parasites, specifically target host lipid droplets during their life c...