Gudmundur Hrafn Gudmundsson

Gudmundur Hrafn Gudmundsson
University of Iceland | HI · Institute of Life and Environmental Sciences

About

129
Publications
15,537
Reads
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11,001
Citations
Additional affiliations
January 2013 - July 2013
Karolinska Institutet
Position
  • visiting scientist
January 2001 - February 2015
University of Iceland
Position
  • Professor (Full) of Cell Biology
Description
  • Teahing cell Biology Research on innate immunity

Publications

Publications (129)
Article
Full-text available
Aroylated phenylenediamines (APDs) are novel modulators of innate immunity with respect to enhancing the expression of antimicrobial peptides and maintaining epithelial barrier integrity. Here, we present a new study on induction of autophagy in human lung epithelial cells by the APD HO53. Interestingly, HO53 affected autophagy in a dose-dependent...
Article
Full-text available
Vitamin D (VD) is a major regulator of calcium metabolism in many living organisms. In addition, VD plays a key role in regulating innate and adaptive immunity in vertebrates. Neutrophils constitute an important part of the first line of defense against invading microbes; however, the potential effect of VD on neutrophils remains elusive. Thus, in...
Article
Infections caused by multidrug resistant (MDR) Klebsiella pneumoniae are difficult to treat with conventional antibiotics. Thus, alternative strategies to control the growth of MDR Klebsiella are warranted. We hypothesized that activation of innate effector systems could sensitize MDR Klebsiella to conventional antibiotics. Thus, human primary macr...
Article
Full-text available
The innate immune system constitutes the first line of defense against invading pathogens, regulating the normal microbiota and contributes to homeostasis. Today we have obtained detailed knowledge on receptors, signaling pathways, and effector molecules of innate immunity. Our research constellation has focused on ways to induce the expression of...
Article
Full-text available
Tuberculosis (TB) is one of the leading causes of mortality and morbidity, particularly in developing countries, presenting a major threat to the public health. The currently recommended long term treatment regimen with multiple antibiotics is associated with poor patient compliance, which in turn, may contribute to the emergence of multi-drug resi...
Article
Full-text available
Background: Azithromycin (Azm) is a macrolide recognized for its disease-modifying effects and reduction in exacerbation of chronic airway diseases. It is not clear whether the beneficial effects of Azm are due to its anti-microbial activity or other pharmacological actions. We have shown that Azm affects the integrity of the bronchial epithelial...
Article
Mechanical ventilation (MV) is a life-saving therapy for critically ill patients, alleviating the work of breathing and supporting adequate gas exchange. However, MV can cause ventilator induced lung injury (VILI) by baro/volu- and atelectrauma, even lead to acute respiratory distress syndrome (ARDS), and substantially augment mortality. There is a...
Article
Full-text available
Aroylated phenylenediamines (APDs) are novel inducers of innate immunity enhancing cathelicidin gene expression in human bronchial epithelial cell lines. Here we present two newly developed APDs and aimed at defining the response and signaling pathways for these compounds with reference to innate immunity and antimicrobial peptide (AMP) expression....
Article
Ventilator associated pneumonia and sepsis are frequent complications in neonatal care. Bacterial colonization of medical devices and interfaces used for respiratory support may contribute by functioning as a bacterial reservoir seeding bacteria into airways. We have developed an antibacterial surface coating based on a cysteine ligand covalently c...
Preprint
Full-text available
Tuberculosis (TB) is a global pandemic disease caused by Mycobacterium tuberculosis (Mtb) that is responsible for almost 9 million active pulmonary TB cases worldwide and about 1.5 million died from the disease in 2013 [1]. The prevalence of multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB is high and converge with the pandemics of...
Article
Full-text available
Background: We have previously shown that 8 weeks' treatment with phenylbutyrate (PBA) (500mgx2/day) with or without vitamin D3 (vitD3) (5000 IU/day) as host-directed therapy (HDT) accelerated clinical recovery, sputum culture conversion and increased expression of cathelicidin LL-37 by immune cells in a randomized, placebo-controlled trial in adu...
Data
Effects of lactose on pancreatic B and T cells following acute pancreatitis induction. Female BALB/c mice were treated with caerulein together with or without lactose and 3 h later cells were recovered from the pancreas. Cells were directly stained for the expression of CD45, Ly6G, CD11b, CD19, and TCRβ. B and T cell numbers per pancreas were shown...
Data
Lactose treatment modulates the severity of experimental AP-associated lung injury. Lung myeloperoxidase activity (A) and histology (B) were determined. Vehicle: saline treatment. Caerulein: caerulein hyperstimulation treatment. Prophylactic: lactose administered 30 min before starting caerulein treatment. Therapeutic: lactose administered 1 h afte...
Article
Full-text available
Acute pancreatitis (AP) is one common clinical acute abdominal disease, for which specific pharmacological or nutritional therapies remain elusive. Lactose, a macronutrient and an inducer of host innate immune responses, possesses immune modulatory functions. The current study aimed to investigate potential modulatory effects of lactose and the int...
Article
Full-text available
Airway epithelium restricts penetration of inhaled pathogens into the underlying tissue and plays a crucial role in innate immune defense against respiratory infections. The whooping cough agent, Bordetella pertussis, adheres to ciliated cells of human airway epithelium and subverts its defense functions through the action of secreted toxins and ot...
Chapter
One promising approach to meet the growing problem of antibiotic resistance is to modulate host defense mechanisms, i.e., host-directed therapy (HDT), in the fight against infections. Induction of endogenous antimicrobial peptides (AMPs) via small molecular compounds, such as 1,25-dihydroxyvitamin D3 or phenylbutyrate, could provide one such HDT-ba...
Article
Maintaining fish health is one of the most important aims in aquaculture. Prevention of fish diseases therefore is crucial and can be achieved by various different strategies, including most often a combination of different methods such as optimal feed and fish density, as well as strengthening the immune system. Understanding the fish innate immun...
Article
Full-text available
We have previously shown that oral treatment of an experimental model of shigellosis with sodium butyrate or phenylbutyrate improves clinical outcome and induces the expression of the antimicrobial peptide CAP-18 in the large intestinal epithelia. In a subsequent study, we have found that Entinostat, an aroylated phenylenediamine compound has simil...
Article
Full-text available
A new concept for treatment of infections is induction of our own antimicrobial peptides and the presented novel class of inducer, aroylated phenylenediamines (APDs), gives up to 20 to 30-fold induction of the human antimicrobial peptide LL-37, in vitro. In addition, oral administration of an APD in a rabbit model of Shigellosis resulted in recover...
Article
Full-text available
Bacterial resistance against classical antibiotics is a growing problem and the development of new antibiotics is limited. Thus, novel alternatives to antibiotics are warranted. Antimicrobial peptides (AMPs) are effector molecules of innate immunity that can be induced by several compounds, including vitamin D and phenyl-butyrate (PBA). Utilizing a...
Article
Full-text available
Mechanical ventilation (MV) of patients can cause damage to bronchoalveolar epithelium, leading to a sterile inflammatory response, infection and in severe cases sepsis. Limited knowledge is available on the effects of MV on the innate immune defense system in the human lung. In this study, we demonstrate that cyclic stretch of the human bronchial...
Data
Cyclic stretch down-regulates human beta defensin 1 (DEFB1) gene expression VA10 cells were subjected to cyclic stretch for 6 h and 24 h. The mRNA expression of DEFB1 was analyzed with q-RT PCR (n = 3, mean ± S.E. ). Relative expression levels (y-axis) in static cells were defined with an arbitrary value of ‘1’ and changes relative to this value in...
Article
Full-text available
Cathelicidins are pleiotropic antimicrobial peptides largely described for innate antimicrobial defenses and, more recently, immunomodulation. They are shown to modulate a variety of immune or nonimmune host cell responses. However, how cathelicidins are expressed by β cells and modulate β-cell functions under steady-state or proinflammatory condit...
Article
Full-text available
Background: Development of new tuberculosis (TB) drugs and alternative treatment strategies are urgently required to control the global spread of TB. Previous results have shown that vitamin D3 (vitD3) and 4-phenyl butyrate (PBA) are potent inducers of the host defense peptide LL-37 that possess anti-mycobacterial effects. Objective: To examine...
Article
Glucocorticoids (GCs) have been extensively used as the mainstream treatment for chronic inflammatory disorders. The persistent use of steroids in the past decades and the association with secondary infections warrants for detailed investigation into their effects on the innate immune system and the therapeutic outcome. In this study, we analyse th...
Article
Full-text available
LL-37 is a human antimicrobial peptide (AMP) of the cathelicidin family with multiple activities including a mediator of vitamin D-induced autophagy in human macrophages, resulting in intracellular killing of Mycobacterium tuberculosis (Mtb). In a previous trial in healthy volunteers, we have shown that LL-37 expression and subsequent Mtb-killing c...
Article
Full-text available
Antibiotics exert several effects on host cells including regulation of immune components. Antimicrobial peptides (AMPs), e.g., cathelicidins and defensins display multiple functions in innate immunity. In colonic mucosa, cathelicidins are induced by butyrate, a bacterial fermentation product. Here, we investigated the effect of antibiotics on buty...
Article
Full-text available
Unlabelled: At birth, the foetus makes the transition from the uterus to a world full of microbes. The newborn baby needs protection against potential invading pathogens and needs to establish a normal microbiota. Conclusion: Antimicrobial peptides and proteins are key effector molecules of innate immunity and are also important immunomodulators...
Article
Full-text available
Rationale: Progress has been made in understanding how the cystic fibrosis (CF) basic defect produces lung infection susceptibility. However, it remains unclear why CF exclusively leads to chronic infections that are noninvasive and highly resistant to eradication. Although biofilm formation has been suggested as a mechanism, recent work raises qu...
Chapter
Endogenous antimicrobial peptides (AMPs) are gene encoded and can be considered as our own antibiotics. These peptides represent an ancient system since they are widespread in nature and have been identified in invertebrates, vertebrates, mammals and also in plants. Defensins and cathelicidins are the main families of AMPs in mammals including huma...
Article
Antimicrobial peptides are important for a healthy host-microbe homeostasis. In infections characterized by low levels of the human cathelicidin, LL-37, induction of its expression increases clearance of pathogens. Our aim was to discover signaling pathways and compounds capable of affecting the expression of LL-37. We recently observed a synergist...
Article
Full-text available
Treatment of shigellosis in rabbits with phenylbutyrate reduces clinical severity and counteracts down-regulation of cathelicidin (CAP-18) in the large intestinal epithelia. We aimed to further evaluate whether in a rabbit model of enteropathogenic Escherichi coli (EPEC) diarrhea, CAP-18 is down-regulated in the small intestine and if oral phenylbu...
Article
Full-text available
Innate immunity, the front line of our defence against pathogens, relies, to a great extent, on the production of antimicrobial peptides (AMPs). These peptides exhibit antimicrobial activity and immunomodulatory properties. In humans, AMPs include the defensins (α- and β-families) and the cathelicidin, LL-37. Bacterial resistance against antibiotic...
Article
Full-text available
Background We earlier showed that 4-phenylbutyrate (PB) can induce cathelicidin LL-37 expression synergistically with 1,25-dihydroxyvitamin D3 in a lung epithelial cell line. We aimed to evaluate a therapeutic dose of PB alone or in combination with vitamin D3 for induction of LL-37 expression in immune cells and enhancement of antimycobacterial ac...
Article
Full-text available
Postpartum, infants have not yet established a fully functional adaptive immune system and are at risk of acquiring infections. Hence, newborns are dependent on the innate immune system with its antimicrobial peptides (AMPs) and proteins expressed at epithelial surfaces. Several factors in breast milk are known to confer immune protection, but whic...
Article
Full-text available
Treatment of shigellosis in rabbits with butyrate reduces clinical severity and counteracts the downregulation of cathelicidin (CAP-18) in the large intestinal epithelia. Here, we aimed to evaluate whether butyrate can be used as an adjunct to antibiotics in the treatment of shigellosis in patients. A randomized, double-blind, placebo-controlled, p...
Article
Antimicrobial peptides are essential elements of epithelial defense against invading micro-organisms. The palatine tonsils are positioned at the entry of the airway and the gut and as such are ideally situated to act as immune sentinels in the pharynx protecting against microbial invasion. Tonsils express a number of antimicrobial peptides includin...
Article
Full-text available
Cathelicidins are among the best characterized antimicrobial peptides and have been shown to have an important role in mammalian innate immunity. We recently isolated a novel mature cathelicidin peptide (codCath) from Atlantic cod and in the present study we functionally characterized codCath. The peptide demonstrated salt sensitivity with abrogati...
Article
Antimicrobial peptides are present in all walks of life, from plants to animals, and they are considered to be endogenous antibiotics. In general, antimicrobial peptides are determinants of the composition of the microbiota and they function to fend off microbes and prevent infections. Antimicrobial peptides eliminate micro-organisms through disrup...
Data
Computerized image analysis for detection of immunostaining. (DOC)
Article
Full-text available
Cathelicidins and defensins are endogenous antimicrobial peptides (AMPs) that are downregulated in the mucosal epithelia of the large intestine in shigellosis. Oral treatment of Shigella infected rabbits with sodium butyrate (NaB) reduces clinical severity and counteracts the downregulation of cathelicidin (CAP-18) in the large intestinal epithelia...
Article
Shigella is a major cause of morbidity and mortality for children in many developing countries. Emergence of antibiotic-resistance among Shigella demands the development of effective medicines. Antimicrobial peptides (AMPs) are expressed in phagocytes and at epithelial surfaces and are important effector molecules of innate immunity. We have found...
Article
Full-text available
Antimicrobial peptides (AMPs) are important components of our first line of defense. Induction of AMPs such as LL-37 of the cathelicidin family might provide a novel approach in treating bacterial infections. In this study we identified 4-phenylbutyrate (PBA) as a novel inducer of AMP expression and investigated affected regulatory pathways. We tre...
Article
Full-text available
Tight junctions (TJs) play a key role in maintaining bronchial epithelial integrity, including apical-basolateral polarity and paracellular trafficking. Patients with chronic obstructive pulmonary disease (COPD) and cystic fibrosis (CF) often suffer from chronic infections by the opportunistic Gram-negative bacterium Pseudomonas aeruginosa, which p...
Article
Mammalian antimicrobial peptides contribute to the protective barrier against microbes at epithelial surfaces. This study focuses on the promoter of the human CAMP gene, encoding the antimicrobial peptide LL-37, and induction of the gene in the colonic epithelial cell line HT-29. CAMP promoter segments were inserted in front of a luciferase reporte...
Article
Full-text available
Cathelicidins are antimicrobial peptides, well studied in mammals and found to be multifunctional proteins, important in the fight against bacterial invasion. Cathelicidins in fish have only recently been identified and little is known about their function and importance in the immune system of fish. In this study we have identified several novel c...