RESUMO
The production of IL-1-family cytokines such as IL-1ß and IL-18 is finely regulated by inflammasome activation after the recognition of pathogens associated molecular pattern (PAMPs) and danger associated molecular patterns (DAMPs). However, little is known about the helminth-derived molecules capable of activating the inflammasome. In the case of the helminth trematode Fasciola hepatica, the secretion of different cathepsin L cysteine peptidases (FhCL) is crucial for the parasite survival. Among these enzymes, cathepsin L3 (FhCL3) is expressed mainly in the juvenile or invasive stage. The ability of FhCL3 to digest collagen has demonstrated to be critical for intestinal tissue invasion during juvenile larvae migration. However, there is no information about the interaction of FhCL3 with the immune system. It has been shown here that FhCL3 induces a non-canonical inflammasome activation in dendritic cells (DCs), leading to IL-1ß and IL-18 production without a previous microbial priming. Interestingly, this activation was depending on the cysteine protease activity of FhCL3 and the NLRP3 receptor, but independent of caspase activation. We also show that FhCL3 is internalized by DCs, promoting pro-IL-1ß cleavage to its mature and biologically active form IL-1ß, which is released to the extracellular environment. The FhCL3-induced NLRP3 inflammasome activation conditions DCs to promote a singular adaptive immune response, characterized by increased production of IFN-γ and IL-13. These data reveal an unexpected ability of FhCL3, a helminth-derived molecule, to activate the NLRP3 inflammasome, which is independent of the classical mechanism involving caspase activation.
Assuntos
Catepsina L/imunologia , Células Dendríticas/imunologia , Fasciola hepatica/imunologia , Proteínas de Helminto/imunologia , Inflamassomos/imunologia , Proteína 3 que Contém Domínio de Pirina da Família NLR/imunologia , Animais , Inflamassomos/genética , Interleucina-18/genética , Interleucina-18/imunologia , Interleucina-1beta/genética , Interleucina-1beta/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Knockout , Proteína 3 que Contém Domínio de Pirina da Família NLR/genéticaRESUMO
Cathepsin L (CTSL) is a ubiquitously expressed lysosomal cysteine peptidase with diverse and highly specific functions. The involvement of CTSL in thymic CD4+ T-cell positive selection has been well documented. Using CTSL(nkt/nkt) mice that lack CTSL activity, we have previously demonstrated that the absence of CTSL activity affects the homeostasis of the T-cell pool by decreasing CD4+ cell thymic production and increasing CD8+ thymocyte production. Herein we investigated the influence of CTSL activity on the homeostasis of peripheral B-cell populations and bone marrow (BM) B-cell maturation. B-cell numbers were increased in lymph nodes (LN), spleen and blood from CTSL (nkt/nkt) mice. Increases in splenic B-cell numbers were restricted to transitional T1 and T2 cells and to the marginal zone (MZ) cell subpopulation. No alterations in the proliferative or apoptosis levels were detected in peripheral B-cell populations from CTSL (nkt/nkt) mice. In the BM, the percentage and the absolute number of pre-pro-B, pro-B, pre-B, immature and mature B cells were not altered. However, in vitro and in vivo experiments showed that BM B-cell production was markedly increased in CTSL (nkt/nkt) mice. Besides, BM B-cell emigration to the spleen was increased in CTSL (nkt/nkt) mice. Colony-forming unit pre-B (CFU pre-B) assays in the presence of BM stromal cells (SC) and reciprocal BM chimeras revealed that both BM B-cell precursors and SC would contribute to sustain the increased B-cell hematopoiesis in CTSL (nkt/nkt) mice. Overall, our data clearly demonstrate that CTSL negatively regulates BM B-cell production and output therefore influencing the homeostasis of peripheral B cells.
Assuntos
Subpopulações de Linfócitos B/citologia , Catepsina L/imunologia , Linfopoese/imunologia , Células Precursoras de Linfócitos B/citologia , Animais , Apoptose , Subpopulações de Linfócitos B/enzimologia , Subpopulações de Linfócitos B/imunologia , Células da Medula Óssea/citologia , Células da Medula Óssea/enzimologia , Células da Medula Óssea/imunologia , Linfócitos T CD4-Positivos/citologia , Linfócitos T CD4-Positivos/imunologia , Catepsina L/deficiência , Catepsina L/genética , Proliferação de Células , Regulação da Expressão Gênica , Homeostase , Linfonodos/citologia , Linfonodos/enzimologia , Linfonodos/imunologia , Camundongos , Camundongos Knockout , Células Precursoras de Linfócitos B/enzimologia , Células Precursoras de Linfócitos B/imunologia , Baço/citologia , Baço/enzimologia , Baço/imunologia , Células-Tronco/citologia , Células-Tronco/enzimologia , Células-Tronco/imunologiaRESUMO
Cathepsin L-like proteases are secreted by several parasites including Taenia solium. The mechanism used by T. solium oncospheres to degrade and penetrate the intestine and infect the host is incompletely understood. It is assumed that intestinal degradation is driven by the proteolytic activity of enzymes secreted by the oncosphere. Blocking the proteolytic activity by an antibody response would prevent the oncosphere penetration and further infection. Serine and cysteine proteases including chymotrypsin, trypsin, elastase, and cathepsin L, are secreted by T. solium and Taenia saginata oncospheres when cultured in vitro, being potential vaccine candidates. However, the purification of a sufficient quantity of proteases secreted by oncospheres to conduct a vaccine trial is costly and lengthy. A 53/25 kDa cathepsin L-like fraction partially purified from T. solium cyst fluid was described previously as an important antigen for immunodiagnostics. In this study we found that this antigen is present in the T. solium oncosphere and is also secreted by the cysticercus. This protein fraction was tested for its ability to protect pigs against an oral challenge with T. solium oncospheres in a vaccine trial. IgG antibodies against the 53/25 kDa cathepsin L-like protein fraction were elicited in the vaccinated animals but did not confer protection.
Assuntos
Cisticercose/imunologia , Cysticercus/imunologia , Proteínas de Helminto/imunologia , Imunoglobulina G/biossíntese , Doenças dos Suínos/parasitologia , Taenia solium/imunologia , Animais , Antígenos de Helmintos/imunologia , Catepsina L/imunologia , Cisticercose/parasitologia , Cysticercus/fisiologia , Proteínas de Helminto/fisiologia , Imunoglobulina G/efeitos dos fármacos , Peso Molecular , Suínos , Doenças dos Suínos/imunologia , Taenia solium/fisiologia , Vacinas/imunologia , Vacinas/farmacologiaRESUMO
Human neurocysticercosis (NCC), caused by the cestode Taenia solium, is responsible for a significant amount of neurological morbidity and epilepsy in developing countries. The disease remains highly endemic in many areas, despite several efforts and interventions to control it. A simple, cheap and fast diagnostic assay that is suitable for use in field conditions is highly desired. In immunodiagnostics based on western immunoblots or standard ELISA, a cathepsin-L-like protein purified from the cysticercus fluid has previously performed well as an antigen. In a recent study in Peru, the same 53/25-kDa antigen was therefore used in the development of a dot-ELISA that could be employed for mass screenings under field conditions. The assay was standardized and tested not only against sera from a large group of NCC cases but also against sera from patients with other common parasitic infections, so that sensitivity and specificity could be assessed. For NCC, the assay gave better sensitivity in the detection of individuals with extraparenchymal cysts (94·4%-100%) or multiple parenchymal cysts (74·6%-80·0%) than in the detection of individuals with single parenchymal cysts (29·4%-45·1%). The assay also showed a high specificity for NCC (99·0%-100%), with a very low level of cross-reactivity with other parasitic infections. The dot-ELISA developed in this study is a highly specific, simple, cheap and rapid test for NCC that could be used under field conditions, even in the low-resource settings that are common in developing countries.