RESUMEN
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-1ß, may recruit more naïve neutrophils into the inflammatory site. Neutralization studies suggest that IL-17A contributed to an enhanced inflammatory response, whereas IL-1ß 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.
Asunto(s)
Coinfección/inmunología , Interleucina-17/inmunología , Leishmania major/fisiología , Leishmaniasis Cutánea/inmunología , Infecciones Estafilocócicas/inmunología , Staphylococcus aureus/fisiología , Animales , Coinfección/microbiología , Coinfección/parasitología , Coinfección/patología , Femenino , Humanos , Interleucina-17/genética , Interleucina-1beta/genética , Interleucina-1beta/inmunología , Leishmania major/genética , Leishmania major/aislamiento & purificación , Leishmaniasis Cutánea/genética , Leishmaniasis Cutánea/parasitología , Leishmaniasis Cutánea/patología , Ratones , Ratones Endogámicos C57BL , Neutrófilos/inmunología , Infecciones Estafilocócicas/genética , Infecciones Estafilocócicas/microbiología , Infecciones Estafilocócicas/patología , Staphylococcus aureus/genética , Staphylococcus aureus/aislamiento & purificación , Células Th17/inmunologíaRESUMEN
BACKGROUND: The Leishmania spp. protozoa are introduced into humans through a sand fly blood meal, depositing the infectious metacyclic promastigote form of the parasite into human skin. Parasites enter a variety of host cells, although a majority are found in macrophages where they replicate intracellularly during chronic leishmaniasis. Symptomatic leishmaniasis causes considerable human morbidity in endemic regions. The Leishmania spp. evade host microbicidal mechanisms partially through virulence-associated proteins such as the major surface protease (MSP or GP63), to inactivate immune factors in the host environment. MSP is a metalloprotease encoded by a tandem array of genes belonging to three msp gene classes, whose mRNAs are differentially expressed in different life stages of the parasite. Like other cells, Leishmania spp. release small membrane-bound vesicles called exosomes into their environment. The purpose of this study was to detect MSP proteins in exosomal vesicles of Leishmania spp. protozoa. METHODS: Using mass spectrometry data we determined the profile of MSP class proteins released in L. infantum exosomes derived from promastigotes in their avirulent procyclic (logarithmic) stage and virulent stationary and metacyclic stages. MSP protein isoforms belonging to each of the three msp gene classes could be identified by unique peptides. RESULTS: Metacyclic promastigote exosomes contained the highest, and logarithmic exosomes had the lowest abundance of total MSP. Among the MSP classes, MSPC class had the greatest variety of isoforms, but was least abundant in all exosomes. Nonetheless, all MSP classes were present at higher levels in exosomes released from stationary or metacyclic promastigotes than logarithmic promastigotes. CONCLUSIONS: The data suggest the efficiency of exosome release may be more important than the identity of MSP isoform in determining the MSP content of Leishmania spp. exosomes.
Asunto(s)
Exosomas/metabolismo , Leishmania infantum/metabolismo , Péptido Hidrolasas/metabolismo , Proteínas Protozoarias/metabolismo , Factores de Virulencia/metabolismo , Animales , Transporte Biológico , Cricetinae , Exosomas/química , Exosomas/genética , Humanos , Leishmania infantum/química , Leishmania infantum/genética , Leishmania infantum/crecimiento & desarrollo , Leishmaniasis Visceral/parasitología , Masculino , Espectrometría de Masas , Mesocricetus , Péptido Hidrolasas/química , Péptido Hidrolasas/genética , Isoformas de Proteínas/química , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Proteínas Protozoarias/química , Proteínas Protozoarias/genética , Factores de Virulencia/química , Factores de Virulencia/genéticaRESUMEN
The role of the nucleotide-binding domain and leucine-rich repeat containing receptor NLRP10 in disease is incompletely understood. Using three mouse strains lacking the gene encoding NLRP10, only one of which had a coincidental mutation in DOCK8, we documented a role for NLRP10 as a suppressor of the cutaneous inflammatory response to Leishmania major infection. There was no evidence that the enhanced local inflammation was due to enhanced inflammasome activity. NLRP10/DOCK8-deficient mice harbored lower parasite burdens at the cutaneous site of inoculation compared with wild-type controls, whereas NLRP10-deficient mice and controls had similar parasite loads, suggesting that DOCK8 promotes local growth of parasites in the skin, whereas NLRP10 does not. NLRP10-deficient mice developed vigorous adaptive immune responses, indicating that there was not a global defect in the development of Ag-specific cytokine production. Bone marrow chimeras showed that the anti-inflammatory role of NLRP10 was mediated by NLRP10 expressed in resident cells in the skin rather than by bone marrow-derived cells. These data suggest a novel role for NLRP10 in the resolution of local inflammatory responses during L. major infection.