Parasite Immunology最新文献

Toll-like receptors (TLRs) and inflammasomes belong to the pattern recognition receptors (PRRs) of innate immunity identifying conserved compounds produced by pathogens or discharged by injured cells. Different cell subsets in the human urogenital system, such as epithelial cells and infiltrating leukocytes, express different kinds of TLRs (such as TLR2, TLR3, TLR4, TLR5 and TLR9) as well as inflammasomes (such as NLRP3, NLRC4 and AIM2). Various types of the Trichomonas vaginalis-derived components such as glycosyl-phosphatidylinositol (GPI), T. vaginalis virus (TVV), Lipophosphoglycan (LPG) and flagellin can be recognized by TLR2, TLR3, TLR4 and TLR5, respectively, leading to the production of proinflammatory cytokines and chemokines in the cervicovaginal mucosa. The T. vaginalis-induced inflammasomes can lead to pyroptosis as well as the release of IL-1β and IL-18 promoting innate and adaptive immune responses. The PRR-mediated responses to T. vaginalis may contribute to the induction of protective immune responses, local inflammation, promotion of co-infections, or even the development of malignancies, for example, prostate cancer. The protective or pathogenic roles of the TLRs and inflammasomes during trichomoniasis are highlighted in this review. A better understanding of PRR-mediated responses provides invaluable insights to develop effective immunotherapeutic strategies against T. vaginalis infection.

Toxoplasma gondii is a zoonotic parasite with a global distribution. Heterophil extracellular traps (HETs) are a novel innate immune mechanism of chickens against pathogens, but whether T. gondii can induce HETs release in chickens has not been reported. The effects of T. gondii on heterophils viability were assessed by using Cell Counting Kit-8. T. gondii-induced HETs were observed and analysed by the immunofluorescence method. T. gondii-induced reactive oxygen species (ROS) was determined by the DCFH-DA method. The mechanisms underlying T. gondii-triggered HETs were investigated by inhibitors and fluorescence microplate reader. T. gondii did not significantly affect heterophils viability at a 1:1 ratio within 1 h. It was demonstrated for the first time that T. gondii could induce HETs release in chicken, and the structure of HETs was comprised of DNA, elastase and citrullinated histone 3 (citH3). T. gondii increased ROS production in a dose-dependent manner. Inhibitors of NADPH oxidase, extracellular signal-regulated kinase 1/2 (ERK_1/2 ) and P38 signalling pathways, glycolysis and autophagy significantly decreased the release of T. gondii-induced HETs. Taken together, T. gondii can induce HETs release in chickens, and ROS, NADPH oxidase, ERK_1/2 and P38 signalling pathways, glycolysis and autophagy participate in the process of HETs release, which provides new insights into the innate immune mechanism of chickens against T. gondii infection.

Intestinal helminth infection promotes a Type 2 inflammatory response in resistant C57BL/6 mice that is essential for worm clearance. The study of inbred mouse strains has revealed factors that are critical for parasite resistance and delineated the role of Type 1 versus Type 2 immune responses in worm clearance. In C57BL/6 mice, basophils are key innate immune cells that promote Type 2 inflammation and are programmed via the Notch signalling pathway during infection with the helminth Trichuris muris. However, how the host genetic background influences basophil responses and basophil expression of Notch receptors remains unclear. Here we use genetically susceptible inbred AKR/J mice that have a Type 1-skewed immune response during T. muris infection to investigate basophil responses in a susceptible host. Basophil population expansion occurred in AKR/J mice even in the absence of fulminant Type 2 inflammation during T. muris infection. However, basophils in AKR/J mice did not robustly upregulate expression of the Notch2 receptor in response to infection as occurred in C57BL/6 mice. Blockade of the Type 1 cytokine interferon-γ in infected AKR/J mice was not sufficient to elicit infection-induced basophil expression of the Notch2 receptor. These data suggest that the host genetic background, outside of the Type 1 skew, is important in regulating basophil responses during T. muris infection in susceptible AKR/J mice.

There is now sufficient evidence to support an inverse association between helminth infection and secreted products with allergic/autoimmune disorders. Accordingly, several experimental studies have shown that Echinococcus granulosus infection and hydatid cyst compounds are able to suppress immune responses in allergic airway inflammation. This is the first study on effects of somatic antigens of E. granulosus on chronic allergic airway inflammation in BALB/c mice. Mice in OVA group were intraperitoneally (IP) sensitized with OVA/Alum. Subsequently, were challenged by nebulizing of OVA 1%. The treatment groups received somatic antigens of protoscoleces on the specified days. Mice in PBS group were received PBS in both sensitization and challenge. The effects of somatic products on development of chronic allergic airway inflammation were evaluated by examining histopathological changes, the recruitment of inflammatory cells in the bronchoalveolar lavage, cytokines production in the homogenized lung tissue, and total antioxidant capacity in serum. Our findings show that the co-administration of somatic antigens of protoscoleces simultaneously with the development of asthma intensifies allergic airway inflammation. The identification of effective components involved in exacerbation of allergic airway inflammation manifestations will be a crucial approach to understanding the mechanism of these interactions.

Intestinal tuft cells have been shown to induce type 2 immune responses during viable parasite infections, but whether oral supplementation with a parasitic exudate is able to promote type 2 immune responses that have been shown to positively regulate obesogenic metabolic processes is yet unresolved. High-fat fed mice were gavaged with pseudocoelomic fluid (PCF) derived from the helminth Ascaris suum or saline thrice a week during weeks 5-9, followed by examination of intestinal tuft cell activity, immune, and metabolic parameters. Helminth PCF upregulated expression of distinct genes in small intestinal tuft cells, including genes involved in regulation of RUNX1 and organic cation transporters. Helminth PCF also enhanced levels of innate lymphoid cells in the ileum, and eosinophils in epididymal white adipose tissue (eWAT). Network analyses revealed two distinct immunometabolic cues affected by oral helminth PCF in high-fat fed mice: one coupling the small intestinal tuft cell responses to the fat-to-lean mass ratio and a second coupling eosinophils in eWAT to general regulation of body fat mass. Our findings point to specific mechanisms by which oral supplementation with helminth PCF may translate into systems-wide effects linking to reduced body and fat mass gain in mice during high-fat feeding.

Leishmaniasis is considered as one of the 20 neglected tropical diseases. Current methods of leishmanial diagnosis depend on conventional laboratory-based techniques, which are time-consuming, costly and require special equipment and trained personnel. In this context, we aimed to provide an immuno field effect transistors (ImmunoFET) biosensor that matches the conventional standards for point-of-care (POC) monitoring and detection of Leishmania (L.) donovani/Leishmania major. Crude antigens prepared by repeated freeze thawing of L. donovani/L. major stationary phase promastigotes were used for ELISA and ImmunoFETs. Lesishmania-specific antigens were serially diluted in 1× PBS from a concentration of 10⁶ -10² parasites/mL. A specific polyclonal antibody-based sandwich ELISA was established for the detection of Leishmania antigens. An immunoFET technology-based POC novel assay was constructed for the detection of Leishmania antigens. Interactions between antigen-antibody at the gate surface generate an electrical signal that can be measured by semiconductor field-effect principles. Sensitivity was considered and measured as the change in current divided by the initial current. The final L. donovani/L. major crude antigen protein concentrations were measured as 1.50 mg/mL. Sandwich ELISA against the Leishmania 40S ribosomal protein detected Leishmania antigens could detect as few as 100 L. donovani/L. major parasites. An immunoFET biosensor was constructed based on the optimization of aluminium gallium nitride/gallium nitride (AlGaN/GaN) surface oxidation methods. The device surface was composed by an AlGaN/GaN wafer with a 23 nm AlGaN barrier layer, a 2 μm GaN layer on the silicon carbide (SiC) substrate for Leishmania binding, and coated with a specific antibody against the Leishmania 40S ribosomal protein, which was successfully detected at concentrations from 10⁶ to 10² parasites/mL in 1× PBS. At the concentration of 10⁴ parasites, the immunoFETs device sensitivities were 13% and 0.052% in the sub-threshold regime and the saturation regime, respectively. Leishmania parasites were successfully detected by the ImmunoFET biosensor at a diluted concentration as low as 150 ng/mL. In this study, the developed ImmunoFET biosensor performed well. ImmunoFET biosensors can be used as an alternative diagnostic method to ELISA. Increasing the sensitivity and optimization of immuno-FET biosensors might allow earlier and faster detection of leishmaniasis.

Schistosomiasis affects nearly 240 million people in predominately low- and middle-income countries and ranks second in the number of cases and socio-economic burden among all parasitic diseases. Despite the enormous burden posed by schistosomes, our understanding of how schistosomiasis impacts infected human tissues remains limited. Intestinal schistosomiasis in animal models leads to goblet cell hyperplasia, likely increasing mucus production and reflecting an intestinal type 2 immune response. However, it is unknown whether these same changes occur in schistosome-infected humans. Using immunofluorescence and light microscopy, we compared the abundance and morphology of goblet cells in patients diagnosed with schistosomiasis to uninfected controls. The mucin-containing vesicles in goblet cells from schistosome-infected patients were significantly larger (hypertrophic) than uninfected individuals, although goblet cell hyperplasia was absent in chronic human schistosomiasis. In addition, we examined tuft cells in the large intestinal epithelium of control and schistosome-infected patients. Tuft cell numbers expand during helminth infection in mice, but these cells have not been characterized in human parasite infections. We found no evidence of tuft cell hyperplasia during human schistosome infection. Thus, our study provides novel insight into schistosome-associated changes to the intestinal epithelium in humans, suggesting an increase in mucus production by large intestinal goblet cells but relatively minor effects on tuft cell numbers.

Benznidazole (Bz) is the recommended drug for the treatment of Chagas disease; however, its efficacy may vary according to the sensitivity of Trypanosoma cruzi strains to the drug and host immune background. The study evaluated the immune response of peripheral blood mononuclear cells (PBMC) that were infected in vitro with the Colombian strain (Col) and treated with Bz. The co-cultures were incubated for 24 h, 5 and 10 days, where cytokine dosage was performed in the supernatant and evaluation of the cells for CD28⁺ and CTLA-4⁺ molecules in CD4⁺ and CD8⁺ lymphocytes, and CD80⁺ , CD86⁺ and HLA-DR⁺ in CD14⁺ cells. The results showed that Col induced a strong inflammatory response, with an increase in IFN-γ and TNF early in the infection (24 h), however, from 5 days of infection on, TNF production declined, and IL-10 production increased, which may be associated with a control mechanism of the exacerbated inflammatory response. The Bz treatment did not significantly alter the frequencies of the phenotypes evaluated both T cell subsets and CD14⁺ cells. Therefore, this study reinforces the need for typing the patient's strain to guide therapy and promote individualized treatment protocols due to the heterogeneous genetic background among T. cruzi strains.

The mucosal immune system contributes for the largest component of the tissue immune system due to its massive surface area and constant exposure to the microbiota. The gut microbiota comprises a complex micro-ecosystem in the intestine and plays a major role in regulating innate and adaptive immunity. Several studies revealed that infectious diseases involve bidirectional interactions in the gut microenvironment, including changes in the gut microbiota composition. During Plasmodium infection, an increase of pro-inflammatory cells in the lamina propria and a shift in the composition of the gut microbiota contribute to intestinal ecosystem dysbiosis. Although the mechanisms of this dysbiosis is still uncertain, it is thought to be associated with the sequestration of infected red blood cells in the intestinal microvascular system, leading to endothelial villous disruption, and thus activating effector immune cells scattered in the intestinal epithelium and lamina propria. This review provides information on this conjoint interaction which will be beneficial to modulate the host immune response in malaria through manipulation of the gut microbiota composition.

Helminths are metazoan parasites affecting about one third of the worldwide population. Chronic helminth infections (CHIs) confer immunological tolerance to harmless and self-antigens mediated by regulatory T cells (Treg) that are up-regulated. In coronavirus disease 2019 (COVID-19), abnormal adaptive immune response and unrestrained innate immune response could result in local and systemic immune-mediated tissue damage. COVID-19 and CHIs establish complicated immune interactions due to SARS-CoV-2-induced immunological stimulation and CHIs-induced immunological tolerance. However, COVID-19 severity in patients with CHIs is mild, as immuno-suppressive anti-inflammatory cytokines counterbalance the risk of cytokine storm. Here, an overview of the interplay between helminths and COVID-19 severity is given. CHIs through helminth-derived molecules may suppress SARS-CoV-2 entry and associated hyperinflammation through attenuation of the TLR4/NF-kB signalling pathway. In addition, CHIs may reduce the COVID-19 severity by reducing the SARS-CoV-2 entry points at ACE2/DPP4/CD147 axis in the initial phase and immunomodulation in the late phase of the disease by suppressing TLR4/NF-kB signalling pathway.