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1.
Antibiotics (Basel) ; 12(9)2023 Sep 19.
Article in English | MEDLINE | ID: mdl-37760758

ABSTRACT

Anti-microbial peptides provide a powerful toolkit for combating multidrug resistance. Combating eukaryotic pathogens is complicated because the intracellular drug targets in the eukaryotic pathogen are frequently homologs of cellular structures of vital importance in the host organism. The entomopathogenic bacteria (EPB), symbionts of entomopathogenic-nematode species, release a series of non-ribosomal templated anti-microbial peptides. Some may be potential drug candidates. The ability of an entomopathogenic-nematode/entomopathogenic bacterium symbiotic complex to survive in a given polyxenic milieu is a coevolutionary product. This explains that those gene complexes that are responsible for the biosynthesis of different non-ribosomal templated anti-microbial protective peptides (including those that are potently capable of inactivating the protist mammalian pathogen Leishmania donovanii and the gallinaceous bird pathogen Histomonas meleagridis) are co-regulated. Our approach is based on comparative anti-microbial bioassays of the culture media of the wild-type and regulatory mutant strains. We concluded that Xenorhabdus budapestensis and X. szentirmaii are excellent sources of non-ribosomal templated anti-microbial peptides that are efficient antagonists of the mentioned pathogens. Data on selective cytotoxicity of different cell-free culture media encourage us to forecast that the recently discovered "easy-PACId" research strategy is suitable for constructing entomopathogenic-bacterium (EPB) strains producing and releasing single, harmless, non-ribosomal templated anti-microbial peptides with considerable drug, (probiotic)-candidate potential.

3.
NPJ Vaccines ; 8(1): 63, 2023 Apr 25.
Article in English | MEDLINE | ID: mdl-37185599

ABSTRACT

Human infection with the protozoan parasite Trypanosoma cruzi causes Chagas disease for which there are no prophylactic vaccines. Cyclophilin 19 is a secreted cis-trans peptidyl isomerase expressed in all life stages of Trypanosoma cruzi. This protein in the insect stage leads to the inactivation of insect anti-parasitic peptides and parasite transformation whereas in the intracellular amastigotes it participates in generating ROS promoting the growth of parasites. We have generated a parasite mutant with depleted expression of Cyp19 by removal of 2 of 3 genes encoding this protein using double allelic homologous recombination. The mutant parasite line failed to replicate when inoculated into host cells in vitro or in mice indicating that Cyp19 is critical for infectivity. The mutant parasite line also fails to replicate in or cause clinical disease in immuno-deficient mice further validating their lack of virulence. Repeated inoculation of mutant parasites into immuno-competent mice elicits parasite-specific trypanolytic antibodies and a Th-1 biased immune response and challenge of mutant immunized mice with virulent wild-type parasites is 100% effective at preventing death from acute disease. These results suggest that parasite Cyp19 may be candidate for small molecule drug targeting and that the mutant parasite line may warrant further immunization studies for prevention of Chagas disease.

4.
Cell Microbiol ; 23(4): e13295, 2021 04.
Article in English | MEDLINE | ID: mdl-33222354

ABSTRACT

Infection by Trypanosoma cruzi, the protozoan parasite that causes Chagas disease, depends on reactive oxygen species (ROS), which has been described to induce parasite proliferation in mammalian host cells. It is unknown how the parasite manages to increase host ROS levels. Here, we found that intracellular T. cruzi forms release in the host cytosol its major cyclophilin of 19 kDa (TcCyp19). Parasites depleted of TcCyp19 by using CRISPR/Cas9 gene replacement proliferate inefficiently and fail to increase ROS, compared to wild type parasites or parasites with restored TcCyp19 gene expression. Expression of TcCyp19 in L6 rat myoblast increased ROS levels and restored the proliferation of TcCyp19 depleted parasites. These events could also be inhibited by cyclosporin A, (a cyclophilin inhibitor), and by polyethylene glycol-linked to antioxidant enzymes. TcCyp19 was found more concentrated in the membrane leading edges of the host cells in regions that also accumulate phosphorylated p47phox , as observed to the endogenous cyclophilin A, suggesting some mechanisms involved with the translocation process of the regulatory subunit p47phox in the activation of the NADPH oxidase enzymatic complex. We concluded that cyclophilin released in the host cell cytosol by T. cruzi mediates the increase of ROS, required to boost parasite proliferation in mammalian hosts.


Subject(s)
Cyclophilins/metabolism , Cytosol/metabolism , Host-Parasite Interactions , Reactive Oxygen Species/metabolism , Trypanosoma cruzi/growth & development , Trypanosoma cruzi/metabolism , Animals , Cyclophilins/biosynthesis , Cyclophilins/genetics , Cytosol/chemistry , Myoblasts/parasitology , Protozoan Proteins/genetics , Protozoan Proteins/metabolism , Rats , Trypanosoma cruzi/genetics
5.
Vessel Plus ; 42020.
Article in English | MEDLINE | ID: mdl-33089078

ABSTRACT

The vascular endothelium is a vital component in maintaining the structure and function of blood vessels. The endothelial cells (ECs) mediate vital regulatory functions such as the proliferation of cells, permeability of various tissue membranes, and exchange of gases, thrombolysis, blood flow, and homeostasis. The vascular endothelium also regulates inflammation and immune cell trafficking, and ECs serve as a replicative niche for many bacterial, viral, and protozoan infectious diseases. Endothelial dysfunction can lead to vasodilation and pro-inflammation, which are the hallmarks of many severe diseases. Exosomes are nanoscale membrane-bound vesicles that emerge from cells and serve as important extracellular components, which facilitate communication between cells and maintain homeostasis during normal and pathophysiological states. Exosomes are also involved in gene transfer, inflammation and antigen presentation, and mediation of the immune response during pathogenic states. Protozoa are a diverse group of unicellular organisms that cause many infectious diseases in humans. In this regard, it is becoming increasingly evident that many protozoan parasites (such as Plasmodium, Trypanosoma, Leishmania, and Toxoplasma) utilize exosomes for the transfer of their virulence factors and effector molecules into the host cells, which manipulate the host gene expression, immune responses, and other biological activities to establish and modulate infection. In this review, we discuss the role of the vascular endothelium and exosomes in and their contribution to pathogenesis in malaria, African sleeping sickness, Chagas disease, and leishmaniasis and toxoplasmosis with an emphasis on their actions on the innate and adaptive immune mechanisms of resistance.

6.
Infect Immun ; 88(7)2020 06 22.
Article in English | MEDLINE | ID: mdl-32312766

ABSTRACT

Chagas disease, caused by the intracellular protozoan parasite Trypanosoma cruzi, is a public health problem affecting 6 to 8 million people, mainly in Latin America. The role of microRNAs in the pathogenesis of Chagas disease has not been well described. Here, we investigate the role of microRNA-155 (miR-155), a proinflammatory host innate immune regulator responsible for T helper type 1 and type 17 (Th1 and Th17) development and macrophage responses during T. cruzi infection. For this, we compared the survival and parasite growth and distribution in miR-155-/- and wild-type (WT) C57BL/6 mice. The lack of miR-155 caused robust parasite infection and diminished survival of infected mice, while WT mice were resistant to infection. Immunological analysis of infected mice indicated that, in the absence of miR-155, there was decreased interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α) production. In addition, we found that there was a significant reduction of CD8-positive (CD8+) T cells, natural killer (NK) cells, and NK-T cells and increased accumulation of neutrophils and inflammatory monocytes in miR-155-/- mice. Collectively, these data indicate that miR-155 is an important immune regulatory molecule critical for the control of T. cruzi infection.


Subject(s)
Chagas Disease/genetics , Chagas Disease/parasitology , MicroRNAs/genetics , Trypanosoma cruzi , Animals , Chagas Disease/immunology , Chagas Disease/mortality , Cytokines/metabolism , Disease Progression , Disease Susceptibility/immunology , Genetic Predisposition to Disease , Kaplan-Meier Estimate , Mice , Mice, Inbred C57BL , Mice, Knockout , Neutrophils/immunology , Neutrophils/metabolism , Prognosis , Th1 Cells/immunology , Th1 Cells/metabolism , Trypanosoma cruzi/immunology
7.
Am J Case Rep ; 20: 268-273, 2019 Mar 01.
Article in English | MEDLINE | ID: mdl-30820022

ABSTRACT

BACKGROUND The overuse of antibiotics in animals promotes the development of multidrug-resistance predisposing for severe polymicrobial human infections. CASE REPORT We describe a case of spontaneous clostridial myonecrosis due to ulcerative colonic infection with multidrug-resistant Salmonella enterica subsp. enterica, serotype 4,[5],12: i: -. Serotyping of the colonic Salmonella isolate in the index case and the bovine farm outbreak isolates from where the patient worked indicated they were both serotype I 4,[5],12: i: -, which is linked with a multitude of large reported disease outbreaks. Further analysis revealed that they are highly genetically related and antibiotic susceptibility testing indicated that they are phenotypically identical. CONCLUSIONS Enteritis due to human acquisition of multidrug-resistant Salmonella from cattle led to the invasion and dissemination of Clostridium septicum resulting in devastating myonecrotic disease. This highlights the ramifications of co-existence and evolution of pathogenic bacteria in animals and humans and lends support to reducing the use of antibiotics in animals.


Subject(s)
Clostridium Infections/microbiology , Clostridium septicum/isolation & purification , Drug Resistance, Multiple, Bacterial , Muscle, Skeletal/pathology , Salmonella Infections/microbiology , Salmonella enterica/isolation & purification , Clostridium Infections/complications , Clostridium Infections/pathology , Female , Humans , Necrosis , Salmonella Infections/complications , Salmonella Infections/pathology , Young Adult
8.
Front Microbiol ; 9: 2655, 2018.
Article in English | MEDLINE | ID: mdl-30555425

ABSTRACT

The neglected tropical diseases (NTDs) caused by protozoan parasites are responsible for significant morbidity and mortality worldwide. Current treatments using anti-parasitic drugs are toxic and prolonged with poor patient compliance. In addition, emergence of drug-resistant parasites is increasing worldwide. Hence, there is a need for safer and better therapeutics for these infections. Host-directed therapy using drugs that target host pathways required for pathogen survival or its clearance is a promising approach for treating infections. This review will give a summary of the current status and advances of host-targeted therapies for treating NTDs caused by protozoa.

9.
J Med Microbiol ; 64(11): 1369-1374, 2015 Nov.
Article in English | MEDLINE | ID: mdl-26408191

ABSTRACT

Limited data exist evaluating outcomes in patients with serious Streptococcus anginosus group infections, particularly bacteraemia. A retrospective, single-centre cohort study was conducted to characterize potential risk factors along with clinical and microbiological outcomes in patients with S. anginosus group bacteraemia (SAGB). Adult inpatients with SAGB identified using the Verigene Gram-positive blood culture assay between March 2013 and April 2014 were included. Patients aged ≤ 18 or >89 years, those with SAGB identified at an outside facility and those who were incarcerated were excluded. Differences between groups were explored using a Wilcoxon rank-sum test, χ2 test, Student's t-test or Fisher's exact test as appropriate and a two-tailed P value of ≤ 0.05 was considered statistically significant. The 34 patients who met the inclusion criteria were 57 ± 14 (mean ± SD) years old and had a median Charlson co-morbidity index of 4 [interquartile range (IQR) 1-6] and 10 (29%) were immunosuppressed at baseline. Almost half (47%) had received antibiotics in the previous 90 days. Twelve (35%) patients had gastrointestinal malignancies and the commonest source of bacteraemia was the gastrointestinal tract (53%). The primary species responsible for SAGB was S. anginosus (68%), and overall susceptibility to penicillin was 91%. Patients were most often treated with a ß-lactam/ß-lactamase inhibitor combination (36%) for a duration of 8 (IQR 4-13) days. Length of stay (LOS) and infection-related LOS were 10 (IQR 5-17) and 9 (IQR 4-12) days, respectively. Twenty [59%] patients achieved a clinical cure, while 29 (85%) achieved a microbiological cure. Four (12%) patients died and one patient was readmitted within 30  days. In the largest cohort of patients with SAGB to date, gastrointestinal malignancies may have been an important risk factor for SAGB, while rapid identification via a microarray assay likely contributed to improved disease recognition and timely pharmacological and non-pharmacological therapy.


Subject(s)
Bacteremia/microbiology , Microarray Analysis/methods , Streptococcal Infections/microbiology , Streptococcus anginosus/isolation & purification , Adult , Aged , Aged, 80 and over , Anti-Bacterial Agents/pharmacology , Female , Humans , Male , Middle Aged , Retrospective Studies , Streptococcus anginosus/classification , Streptococcus anginosus/drug effects , Streptococcus anginosus/genetics , Young Adult
10.
AIDS Res Hum Retroviruses ; 31(9): 889-92, 2015 Sep.
Article in English | MEDLINE | ID: mdl-26154873

ABSTRACT

Immune reconstitution inflammatory syndrome (IRIS) is an immuno-pathologic reaction to quiescent opportunistic microbial pathogens upon restoration of underlying immune defects. Here we report a Honduran patient with HIV/AIDS who developed a facial rash worsening on antiretroviral therapy and increasing CD4 count. Culture and PCR analysis from the skin biopsy identified Leishmania panamensis, which was effectively treated with long-term liposomal amphotericin B. This is the first report of mucocutaneous leishmaniasis (MCL)-associated IRIS due to L. panamensis.


Subject(s)
AIDS-Related Opportunistic Infections , HIV Infections/complications , Immune Reconstitution Inflammatory Syndrome/complications , Leishmania , Leishmaniasis, Mucocutaneous/etiology , AIDS-Related Opportunistic Infections/drug therapy , AIDS-Related Opportunistic Infections/immunology , Adult , Amphotericin B/administration & dosage , Amphotericin B/therapeutic use , Antiprotozoal Agents/administration & dosage , Antiprotozoal Agents/therapeutic use , Female , HIV Infections/immunology , Humans , Immune Reconstitution Inflammatory Syndrome/immunology , Leishmaniasis, Mucocutaneous/drug therapy , Leishmaniasis, Mucocutaneous/immunology , Polymerase Chain Reaction
11.
Immunology ; 145(2): 225-31, 2015 Jun.
Article in English | MEDLINE | ID: mdl-25545325

ABSTRACT

The control of Trypanosoma cruzi infection is related to interferon-γ (IFN-γ) activation leading to intracellular clearance of parasites. The transcription factor signal transducer and activator of transcription 1 (STAT-1) is a key mediator of IFN-γ intracellular signalling and knockout of this protein leads to susceptibility to several intracellular microbes. To determine the role of STAT-1 in host susceptibility to T. cruzi infection we compared the survival, parasite loads and balance of IFN-γ and interleukin-10 (IL-10) responses between wild-type and STAT-1 knockout mice. We found that the lack of STAT-1 resulted in a more robust infection, leading to higher levels of blood and tissue parasites and markedly reduced survival. In addition, infected STAT-1 knockout mice had higher systemic levels of both IFN-γ and IL-10, suggesting that the absence of STAT-1 leads to a disequilibrium of pro-inflammatory and anti-inflammatory cytokines. Analysis of spleen cells indicates that CD4, CD8 cells generate IFN-γ and natural killer cells express IL-13 in STAT-1 knockout animals. The production of IL-17 is particularly enhanced in the absence STAT-1 expression but did not reduce mortality. Overall these results indicate that STAT-1 is important for the control of T. cruzi infection in mice.


Subject(s)
CD4-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/immunology , Chagas Disease/immunology , Cytokines/immunology , STAT1 Transcription Factor/immunology , Trypanosoma cruzi/immunology , Animals , Chagas Disease/genetics , Cytokines/genetics , Female , Mice , Mice, Knockout , STAT1 Transcription Factor/genetics
12.
Parasitol Res ; 113(5): 1971-6, 2014 May.
Article in English | MEDLINE | ID: mdl-24658630

ABSTRACT

Antimicrobial peptides are increasingly being explored as alternative agents for therapy against the parasitic protozoan Leishmania. Previously, we reported that the synthetic magainin analog, pexiganan, induced apoptosis of surface protease-deficient Leishmania. Here, we report the development of an arginine-rich variant of this peptide which has reduced protease susceptibility and enhanced activity against wild type Leishmania in vitro. This peptide induces calcium delocalization and caspase 3/7 activity indicative of apoptosis, demonstrating that structural modification of pexiganan leads to drastic changes in biologic activity against Leishmania.


Subject(s)
Antimicrobial Cationic Peptides/pharmacology , Antiprotozoal Agents/pharmacology , Leishmania/drug effects , Amino Acid Sequence , Antimicrobial Cationic Peptides/chemistry , Apoptosis/drug effects , Arginine/chemistry , Calcium/metabolism , Caspases/metabolism , Molecular Sequence Data , Parasitic Sensitivity Tests
13.
Cell Mol Life Sci ; 71(7): 1245-63, 2014 Apr.
Article in English | MEDLINE | ID: mdl-24221133

ABSTRACT

Numerous disease-causing parasites must invade host cells in order to prosper. Collectively, such pathogens are responsible for a staggering amount of human sickness and death throughout the world. Leishmaniasis, Chagas disease, toxoplasmosis, and malaria are neglected diseases and therefore are linked to socio-economical and geographical factors, affecting well-over half the world's population. Such obligate intracellular parasites have co-evolved with humans to establish a complexity of specific molecular parasite-host cell interactions, forming the basis of the parasite's cellular tropism. They make use of such interactions to invade host cells as a means to migrate through various tissues, to evade the host immune system, and to undergo intracellular replication. These cellular migration and invasion events are absolutely essential for the completion of the lifecycles of these parasites and lead to their for disease pathogenesis. This review is an overview of the molecular mechanisms of protozoan parasite invasion of host cells and discussion of therapeutic strategies, which could be developed by targeting these invasion pathways. Specifically, we focus on four species of protozoan parasites Leishmania, Trypanosoma cruzi, Plasmodium, and Toxoplasma, which are responsible for significant morbidity and mortality.


Subject(s)
Host-Parasite Interactions , Parasites/physiology , Protozoan Infections/parasitology , Animals , Chagas Disease/immunology , Chagas Disease/parasitology , Humans , Leishmania/immunology , Leishmania/pathogenicity , Leishmania/physiology , Leishmaniasis/immunology , Leishmaniasis/parasitology , Malaria/immunology , Malaria/parasitology , Parasites/pathogenicity , Phagocytes/immunology , Phagocytes/parasitology , Plasmodium/immunology , Plasmodium/pathogenicity , Plasmodium/physiology , Protozoan Infections/immunology , Toxoplasma/immunology , Toxoplasma/pathogenicity , Toxoplasma/physiology , Trypanosoma cruzi/immunology , Trypanosoma cruzi/pathogenicity , Trypanosoma cruzi/physiology
14.
J Biol Chem ; 288(12): 8772-8784, 2013 Mar 22.
Article in English | MEDLINE | ID: mdl-23386612

ABSTRACT

The mechanisms by which Trypanosoma cruzi survives antimicrobial peptides and differentiates during its transit through the gastrointestinal tract of the reduviid vector are unknown. We show that cyclophilin, a peptidyl-prolyl isomerase secreted from T. cruzi epimastigotes, binds to and neutralizes the reduviid antimicrobial peptide trialysin promoting parasite survival. This is dependent on a singular proline residue in trialysin and is inhibited by the cyclophilin inhibitor cyclosporine A. In addition, cyclophilin-trialysin complexes enhance the production of ATP and reductase responses of parasites, which are inhibited by both calcineurin-specific inhibitors cyclosporine A and FK506. Calcineurin phosphatase activity of cyclophilin-trialysin-treated parasites was higher than in controls and was inhibited by preincubation by either inhibitor. Parasites exposed to cyclophilin-trialysin have enhanced binding and invasion of host cells leading to higher infectivity. Leishmanial cyclophilin also mediates trialysin protection and metabolic stimulation by T. cruzi, indicating that extracellular cyclophilin may be critical to adaptation in other insect-borne protozoa. This work demonstrates that cyclophilin serves as molecular sensor leading to the evasion and adaptive metabolic response to insect defense peptides.


Subject(s)
Calcineurin/metabolism , Cyclophilins/physiology , Protozoan Proteins/physiology , Salivary Proteins and Peptides/antagonists & inhibitors , Trypanosoma cruzi/physiology , Adaptation, Biological , Adenosine Triphosphate/metabolism , Amino Acid Sequence , Animals , Cell Line , Cyclophilins/metabolism , Energy Metabolism , Enzyme Activation , Host-Parasite Interactions , Immune Evasion , Leishmania/physiology , Mitochondria/metabolism , Molecular Sequence Data , Oxidoreductases/metabolism , Proline/analogs & derivatives , Proline/chemistry , Protozoan Proteins/metabolism , Rats , Salivary Proteins and Peptides/chemistry , Salivary Proteins and Peptides/physiology , Signal Transduction , Trypanosoma cruzi/enzymology , Trypanosoma cruzi/immunology
15.
Parasitol Res ; 112(5): 2095-9, 2013 May.
Article in English | MEDLINE | ID: mdl-23392902

ABSTRACT

The digenetic protozoan Leishmania is dependent on ergosterol synthesis for growth and viability. We compared the in vitro activity of ergosterol synthesis inhibitor voriconazole with fluconazole and ketoconazole against cutaneous and visceral Leishmania species. We found the IC50 of voriconazole was comparable to ketoconazole and both were superior to fluconazole. Both ketoconazole and voriconazole were active against insect and mammalian stage parasites. This is the first report of the in vitro activity of voriconazole against leishmanial species.


Subject(s)
Leishmania/drug effects , Leishmania/growth & development , Pyrimidines/pharmacology , Triazoles/pharmacology , Animals , Antiprotozoal Agents/pharmacology , Fluconazole/pharmacology , Inhibitory Concentration 50 , Ketoconazole/pharmacology , Leishmania/classification , Parasitic Sensitivity Tests , Species Specificity , Voriconazole
16.
Future Microbiol ; 7(9): 1047-59, 2012 Sep.
Article in English | MEDLINE | ID: mdl-22953706

ABSTRACT

Leishmaniasis is one of the major neglected tropical diseases of the world. It is present in 88 countries with an estimated number of 500,000 cases of visceral leishmaniasis and 1.5 million cases of cutaneous disease. No effective vaccinations are available against leishmaniasis and the efficacy of existing treatments is compromised due to the emergence of drug resistance. Thus, there is an urgent need to develop new compounds with antileishmanial activity. Antimicrobial peptides have potential as novel antileishmanial therapy, either for use alone or in combination with current drug regimens. The modes of action of these peptides against Leishmania includes: membrane disruption leading to necrotic cell death; induction of apoptosis; binding to intracellular target(s); and indirect effects via immunomodulation of host immune cells. This article reviews the mechanisms of action of antimicrobial peptides with leishmanicidal activity.


Subject(s)
Antimicrobial Cationic Peptides/pharmacology , Antiprotozoal Agents/pharmacology , Leishmania/drug effects , Animals , Antimicrobial Cationic Peptides/chemistry , Antiprotozoal Agents/chemistry , Apoptosis , Cell Membrane/drug effects , Humans , Immunomodulation , Leishmaniasis/drug therapy , Leishmaniasis/immunology , Leishmaniasis/parasitology
17.
J Biol Chem ; 286(38): 33109-17, 2011 Sep 23.
Article in English | MEDLINE | ID: mdl-21784841

ABSTRACT

The flagellar calcium-binding protein (FCaBP) of Trypanosoma cruzi is localized to the flagellar membrane in all life cycle stages of the parasite. Myristoylation and palmitoylation of the N terminus of FCaBP are necessary for flagellar membrane targeting. Not all dually acylated proteins in T. cruzi are flagellar, however. Other determinants of FCaBP therefore likely contribute to flagellar specificity. We generated T. cruzi transfectants expressing the N-terminal 24 or 12 amino acids of FCaBP fused to GFP. Analysis of these mutants revealed that although amino acids 1-12 are sufficient for dual acylation and membrane binding, amino acids 13-24 are required for flagellar specificity and lipid raft association. Mutagenesis of several conserved lysine residues in the latter peptide demonstrated that these residues are essential for flagellar targeting and lipid raft association. Finally, FCaBP was expressed in the protozoan Leishmania amazonensis, which lacks FCaBP. The flagellar localization and membrane association of FCaBP in L. amazonensis suggest that the mechanisms for flagellar targeting, including a specific palmitoyl acyltransferase, are conserved in this organism.


Subject(s)
Calcium-Binding Proteins/metabolism , Cilia/metabolism , Intracellular Membranes/metabolism , Protozoan Proteins/metabolism , Trypanosoma cruzi/metabolism , Acylation/drug effects , Amino Acid Sequence , Calcium-Binding Proteins/chemistry , Conserved Sequence , Detergents/pharmacology , Green Fluorescent Proteins/metabolism , Intracellular Membranes/drug effects , Leishmania/drug effects , Leishmania/metabolism , Lysine/metabolism , Molecular Sequence Data , Mutation/genetics , Myristic Acid/metabolism , Palmitates/metabolism , Protein Binding/drug effects , Protein Transport/drug effects , Protozoan Proteins/chemistry , Recombinant Fusion Proteins/metabolism , Subcellular Fractions/drug effects , Subcellular Fractions/metabolism , Trypanosoma cruzi/drug effects
18.
Cell Microbiol ; 13(6): 913-23, 2011 Jun.
Article in English | MEDLINE | ID: mdl-21501359

ABSTRACT

Cathelicidin-type antimicrobial peptides (CAMP) are important mediators of innate immunity against microbial pathogens acting through direct interaction with and disruption of microbial membranes and indirectly through modulation of host cell migration and activation. Using a mouse knock-out model in CAMP we studied the role of this host peptide in control of dissemination of cutaneous infection by the parasitic protozoan Leishmania. The presence of pronounced host inflammatory infiltration in lesions and lymph nodes of infected animals was CAMP-dependent. Lack of CAMP expression was associated with higher levels of IL-10 receptor expression in bone marrow, splenic and lymph node macrophages as well as higher anti-inflammatory IL-10 production by bone marrow macrophages and spleen cells but reduced production of the pro-inflammatory cytokines IL-12 and IFN-γ by lymph nodes. Unlike wild-type mice, local lesions were exacerbated and parasites were found largely disseminated in CAMP knockouts. Infection of CAMP knockouts with parasite mutants lacking the surface metalloprotease virulence determinant resulted in more robust disseminated infection than in control animals suggesting that CAMP activity is negatively regulated by parasite surface proteolytic activity. This correlated with the ability of the protease to degrade CAMP in vitro and co-localization of CAMP with parasites within macrophages. Our results highlight the interplay of antimicrobial peptides and Leishmania that influence the host immune response and the outcome of infection.


Subject(s)
Cathelicidins/immunology , Leishmania/immunology , Leishmaniasis, Cutaneous/immunology , Animals , Antimicrobial Cationic Peptides , Cathelicidins/deficiency , Cytokines/metabolism , Inflammation/immunology , Inflammation/pathology , Leishmaniasis, Cutaneous/pathology , Lymph Nodes/immunology , Macrophages/immunology , Mice , Mice, Inbred BALB C , Mice, Knockout , Models, Biological , Spleen/immunology
19.
Exp Parasitol ; 126(3): 397-405, 2010 Nov.
Article in English | MEDLINE | ID: mdl-20159013

ABSTRACT

Antimicrobial peptides (AMPs) are multifunctional components of the innate systems of both insect and mammalian hosts of the pathogenic trypanosomatids Leishmania and Trypanosoma species. Structurally diverse AMPs from a wide range of organisms have in vitro activity against these parasites acting mainly to disrupt surface-membranes. In some cases AMPs also localize intracellularly to affect calcium levels, mitochondrial function and induce autophagy, necrosis and apoptosis. In this review we discuss the work done in the area of AMP interactions with trypanosomatid protozoa, propose potential targets of AMP activity at the cellular level and discuss how AMPs might influence parasite growth and differentiation in their hosts to determine the outcome of natural infection.


Subject(s)
Antimicrobial Cationic Peptides/physiology , Euglenozoa Infections/immunology , Insecta/parasitology , Trypanosomatina/drug effects , Animals , Antimicrobial Cationic Peptides/immunology , Antimicrobial Cationic Peptides/pharmacology , Euglenozoa Infections/parasitology , Host-Parasite Interactions/drug effects , Host-Parasite Interactions/immunology , Humans , Immunity, Innate , Insecta/immunology , Leishmania/drug effects , Leishmania/growth & development , Leishmania/immunology , Life Cycle Stages/drug effects , Life Cycle Stages/physiology , Trypanosoma brucei brucei/drug effects , Trypanosoma brucei brucei/growth & development , Trypanosoma brucei brucei/immunology , Trypanosoma cruzi/drug effects , Trypanosoma cruzi/growth & development , Trypanosoma cruzi/immunology , Trypanosomatina/growth & development , Trypanosomatina/immunology
20.
J Biol Chem ; 284(23): 15496-504, 2009 Jun 05.
Article in English | MEDLINE | ID: mdl-19357081

ABSTRACT

alpha- and -defensin-, magainin-, and cathelicidin-type antimicrobial peptides (AMPs) can kill the pathogenic protozoan Leishmania. Comparative studies of a panel of AMPs have defined two distinct groups: those that induce nonapoptotic (Class I) and apoptotic (Class II) parasite killing based on their differential ability to induce phosphatidyl serine exposure, loss of mitochondrial membrane potential and decreased ATP production, induction of caspase-3/7 and -12 activity, and DNA degradation. Class II AMPs cause rapid influx of the vital stain SYTOX and an increase in intracellular Ca2+, whereas Class I AMPs cause a slow accumulation of SYTOX and do not affect intracellular Ca2+ levels. Inhibitors of cysteine or caspase proteases diminished fast influx of SYTOX through the surface membrane and DNA degradation but do not ablate the annexin V staining or the induction of apoptosis by Class II AMPs. This suggests that the changes in surface permeability in AMP-mediated apoptosis are related to the downstream events of intracellular cysteine/caspase activation or the loss of ATP. The activation of caspase-12-like activity was Ca(2+)-dependent, and inhibitors of voltage-gated and nonspecific Ca2+ channels diminished this activity. Flufenamic acid, a nonspecific Ca2+ inhibitor, completely ablated AMP-induced mitochondrial dysfunction and cell death, indicating the importance of dysregulation of Ca2+ in antimicrobial peptide-induced apoptosis.


Subject(s)
Antiprotozoal Agents/pharmacology , Caspases/metabolism , Leishmania major/drug effects , Magainins/pharmacology , Mitochondria/pathology , alpha-Defensins/pharmacology , Adenosine Monophosphate/pharmacology , Animals , Antimicrobial Cationic Peptides/pharmacology , Calcium/metabolism , Calcium Channels/drug effects , Calcium Channels/physiology , Cell Line , Cell Membrane Permeability/drug effects , Flow Cytometry , Leishmania major/cytology , Leishmania major/enzymology , Mitochondria/drug effects , Mitochondrial Membranes/drug effects , Mitochondrial Membranes/physiology , Cathelicidins
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