Cyclophilin A from Schistosoma japonicum promotes a Th2 response in mice

Protein expression profile of Taenia crassiceps cysticerci related to Th1- and Th2-type responses in the mouse cysticercosis model

The intraperitoneal cysticercosis model with the Taenia crassiceps ORF strain in female BALB/cAnN mice has been widely used to study the immune response in cysticercosis. During early infection (2 weeks), the host develops a non-permissive Th1 response, whereas during late infection (8 weeks), molecules from the cysticerci induce a Th2 response that is permissive to parasite growth. The modulation of the Th2 response is induced by molecules excreted/secreted by the larval stage of the parasite. However, there is limited information regarding the response of cysticerci to the mouse immunological environment during infection. The proteomic profiles in T. crassiceps ORF cysticerci when faced with the mouse Th1 and Th2 responses were analyzed through two-dimensional gel electrophoresis (2DE), and the differential expression of proteins was evaluated. Thirteen proteins, whose differential expression varied between 70% and 100%, were selected randomly. Protein identification by MALDI-TOF MS and BLAST showed that the proteins were related to folding, signaling, enzymatic activities, cell-movement regulation, cell-cell interactions, motility, carbohydrate metabolism, detoxification, and redox regulation processes. Notably, some of the proteins can act as antigenic-protective molecules and elicit a weak Th1 response; however, most are involved in the avoidance of the immune system, which leads to a Th2 response, or apoptosis. The findings indicate the process by which T. crassiceps cysticerci responds based on the host environment and provides novel insights into the mechanism by which this facilitates its establishment and persistence in the mouse. Furthermore, these proteins could be used as targets for drug and vaccine development.

iTRAQ-Based Comparative Proteomic Analysis of Adult Schistosoma japonicum from Water Buffalo and Yellow Cattle

Schistosomiasis japonicum is one of the most severe zoonotic diseases in China. Water buffalo and yellow cattle are important reservoir hosts and the main transmission sources of Schistosoma japonicum in endemic areas. The susceptibility of these two hosts to schistosome infection is different, as water buffaloes are less susceptible to S. japonicum than yellow cattle. In this study, iTRAQ-coupled LC-MS/MS was applied to compare the protein expression profiles of adult schistosomes recovered from water buffalo with those of yellow cattle. A total of 131 differentially expressed proteins (DEPs) were identified, including 46 upregulated proteins and 85 downregulated proteins. The iTRAQ results were confirmed by Western blotting and quantitative real-time PCR. Further analysis indicated that these DEPs were primarily involved in protein synthesis, transcriptional regulation, protein proteolysis, cytoskeletal structure and oxidative stress response processes. The results revealed that some of the differential expression molecules may affect the development and survival of schistosomes in these two natural hosts. Of note, this study provides useful information for understanding the interplay between schistosomes and their final hosts.

Composition of the Schistosoma mansoni worm secretome: Identification of immune modulatory Cyclophilin A

The helminth Schistosoma mansoni modulates the infected host's immune system to facilitate its own survival, by producing excretory/secretory molecules that interact with a variety of the host's cell types including those of the immune system. Herein, we characterise the S. mansoni adult male worm secretome and identify 111 proteins, including 7 vaccine candidates and several molecules with potential immunomodulatory activity. Amongst the molecules present in the secretome, a 17-19kDa protein analogous to human cyclophilin A was identified. Given the ability of cyclophilin A to modulate the immune system by regulating antigen presenting cell activity, we sought to determine whether recombinant S. mansoni Cyclophilin A (rSmCypA) is capable of modulating bone-marrow derived dendritic cell (BMDC) and T cell responses under in vitro conditions. rSmCypA was enzymatically active and able to alter the pro-inflammatory cytokine profile of LPS-activated dendritic cells. rSmCypA also modulated DC function in the induction of CD4+ T cell proliferation with a preferential expansion of Treg cells. This work demonstrates the unique protein composition of the S. mansoni male worm secretome and immunomodulatory activity of S. mansoni Cyclophilin A.

Microbial cyclophilins: specialized functions in virulence and beyond

Cyclophilins belong to the superfamily of peptidyl-prolyl cis/trans isomerases (PPIases, EC: 5.2.1.8), the enzymes that catalyze the cis/trans isomerization of peptidyl-prolyl peptide bonds in unfolded and partially folded polypeptide chains and native state proteins. Cyclophilins have been extensively studied, since they are involved in multiple cellular processes related to human pathologies, such as neurodegenerative disorders, infectious diseases, and cancer. However, the presence of cyclophilins in all domains of life indicates a broader biological importance. In this mini-review, we summarize current advances in the study of microbial cyclophilins. Apart from their anticipated role in protein folding and chaperoning, cyclophilins are involved in several other biological processes, such as cellular signal transduction, adaptation to stress, control of pathogens virulence, and modulation of host immune response. Since many existing family members do not have well-defined functions and novel ones are being characterized, the requirement for further studies on their biological role and molecular mechanism of action is apparent.

The dynamic changes of CD3e-CD11c+ dendritic cells in spleens and bone marrow of mice infected with Schistosoma japonicum

Schistosoma japonicum as a pathogeny requires dendritic cells to activate immune response. So, the research is to study the dynamic changes of CD3e^-CD11c⁺ dendritic cells in mice infected with S. japonicum. Zero, 7, 28, 35, and 63 days were selected to study the variation of dendritic cells, and the proportions of CD3e^-CD11c⁺ dendritic cells and CD86⁺ mature dendritic cells in spleens and bone marrow were tested by flow cytometry. As a result, the variation trends of dendritic cells in spleen and bone marrow are similar as follows: the proportions of CD3e^-CD11c⁺ dendritic cells increased first and then decreased from day 35, but the percentages of CD86⁺ mature dendritic cells decreased from day 28 and increased in day 63. In vitro, cultured dendritic cells treated with SEA and SAWA were tested by flow cytometry, the variation trends of CD86 on dendritic cells are consistent with the results in days 28 and 63. Besides CD86, the expression of MHC-II also hints immune regulation. In conclusion, it is speculated that dendritic cells play a role of immune regulation through MHC-II and CD86 in S. japonicum infection. Immune regulation of dendritic cells is not only in favor of the survival of host and parasite but also can be used in the therapy for immune diseases.

High-throughput dynamic analysis of differentially expressed genes in splenic dendritic cells from mice infected with Schistosoma japonicum

Dendritic cells are the initiation and key point of immune response and play a role in immune regulation. So we explored the mechanisms involved in immune regulation of dendritic cells (DCs) against schistosomiasis using mice infected with Schistosoma japonicum. Splenic DCs from normal mice and mice with acute and chronic S. japonicum infection were sorted by flow cytometry. The numbers and functions of differentially expressed genes (DEGs) in DCs were determined by high-throughput analysis. All DEGs with transcription-level fold changes of ≥2 were selected and matched to corresponding genes in databases. Annotations and cluster analysis of DEGs were performed to compare differences between groups. Six important DEGs about immune regulation-CD86, TLR2, DC-SIGN, Capase3, PD-L2, and IL-7r were selected, and their transcription levels at different stages of schistosomisis were validated by qPCR. The Venn diagram of DEGs implied some genes are functional at all stages during S. japonicum infection, while others are only involved at certain stages. GO and KEGG pathway annotations indicated that these DEGs mainly belong to biological regulation, regulation of biological process, regulation of cellular process, antigen processing and presentation, cell adhesion molecules, cytokine-cytokine receptor interaction and Toll-like receptor signaling. Cluster analysis revealed immune regulation existed in splenic DCs. The results above indicated that the mechanisms underlying immune regulation to S. japonicum infection in mice are very complex. The present high-throughput dynamic analysis of DEGs in splenic DCs provides valuable insights into the molecular mechanisms underlying immune regulation in S. japonicum infection.

Interleukin-4- and NACHT, LRR and PYD domains-containing protein 3-independent mechanisms of alum enhanced T helper type 2 responses on basophils

Aluminium hydroxide (alum), the most widely used adjuvant in human and animal vaccines, has long been known to promote T helper type 2 (Th2) responses and Th2-associated humoral responses, but the mechanisms have remained poorly understood. In this study, we explored whether alum is able to directly modulate antigen-presenting cells to enhance their potency for Th2 polarization. We found that alum treatment of dendritic cells failed to show any Th2-promoting activities. In contrast, alum was able to enhance the capacity of basophils to induce Th2 cells. When basophils from interleukin-4 (IL-4) knockout mice were examined, the intrinsic Th2-promoting activities by basophils were largely abrogated, but the alum-enhanced Th2-promoting activities on basophils were still detectable. More importantly, Th2-promoting adjuvant activities by alum found in IL-4 knockout mice were also largely reduced when basophils were depleted by antibody administration. Therefore, basophils can mediate Th2-promoting activities by alum both in vitro and in vivo through IL-4-independent mechanisms. Further studies revealed that secreted soluble molecules from alum-treated basophils were able to confer the Th2-promoting activities, and neutralization of thymic stromal lymphopoietin or IL-25 attenuated the IL-4-independent development of Th2 cells elicited by alum-treated basophils. Finally, alum was able to activate NACHT, LRR and PYD domains-containing protein 3 (NLRP3) inflammasome in murine basophils in the same way as alum in professional antigen-presenting cells, but NLRP3 was not required for Th2-promoting activities on basophils by alum in vitro. These results demonstrated that alum can enhance the capacities of basophils to polarize Th2 cells via IL-4- and NLRP3-independent pathways.

Therapeutic potential of recombinant cystatin from Schistosoma japonicum in TNBS-induced experimental colitis of mice

Background

Helminth infections and their components have been shown to have a protective effect on autoimmune diseases. The isolated purified protein from Schisotosoma japonicum and its potential therapeutic effect on trinitrobenzene sulfonic acid (TNBS)-induced colitis could provide an alternative way to treat inflammatory bowel disease (IBDs).

Methods

Colitis was induced in Balb/c mice by rectal administration of 2.5 % TNBS, followed by intraperitoneal injection of rSjcystatin 50 μg at 6 h and 24 h afterwards. The inflammation was monitored by recording weight change, stool character and bleeding, colon length, macroscopic score (MAO), microscopic score (MIO), myeloperoxidase activity (MPO) and disease activity index (DAI). The potential underlying mechanism was investigated by examining cytokine profiles including Th1 (IFNγ), Th2 (IL-4), Th17 (IL-17A) and Treg subsets from lymphocytes of spleen, mesenteric lymph nodes (MLN) and intestinal lamina propria mononuclear cells (LPMCs) by flow cytometry. The mRNA relative expressions of the cytokines in splenocytes and MLN were analysed by quantitative real time reverse-transcriptase polymerase chain reaction (qRT-PCR). Simultaneously, the concentrations of the cytokines in the colon homogenate supernatants were tested by enzyme-linked immunosorbent assay (ELISA) and key transcription factors were detected by Western blotting.

Results

Administration of rSjcystatin significantly reduced inflammatory parameters and ameliorated the severity of the TNBS-induced colitis through decreasing IFNγ in three organs and lifting the level of IL-4, IL-13, IL-10, and TGF-β in the colon tissues, with uptrending Tregs in the MLN and LPMC.

Conclusion

The findings provide evidence that rSjcystatin has a therapeutic potential for diminishing colitis inflammation in Balb/c mice. The immunological mechanism may involve the down-regulation of Th1 response and up-regulation of Th2 and Tregs in the MLN and colon.

IL-4-Producing Dendritic Cells Induced during Schistosoma japonica Infection Promote Th2 Cells via IL-4-Dependent Pathway

Although dendritic cells (DCs) have been widely demonstrated to play essential roles in initiation of Th2 responses in helminth infections and allergic reactions, the mechanisms remain uncertain largely because DCs do not produce IL-4. In present investigation, we have uncovered a novel subset of DCs from mice infected with Th2-provoking pathogens Schistosoma japonica, which independently promoted Th2 cells via IL-4-dependent pathway. These DCs contained similar levels of IL-4 mRNA and higher levels of IL-12p40 mRNA comparing to basophils, correlating to their Th2-promoting and Th1-promoting dual polarization capacities. Characterized by expression of FcεRI(+), these DCs were induced independent of T cells. Further investigations revealed that Th2-promoting FcεRI(+) DCs were monocyte-derived inflammatory DCs, which were sufficient to induce Th2 cells in vivo. Egg Ags together with GM-CSF or IL-3 alone were able to stimulate the generation of Th2-promoting FcεRI(+) DCs from bone marrow cells in vitro. To our knowledge, our data for the first time demonstrate that IL-4-producing DCs are induced under some Th2-provoking situations, and they should play important roles in initiation of Th2 response.

Protective immunity against Schistosoma japonicum infection can be provided by IgG antibodies towards periodate-sensitive or periodate-resistant glycans

BACKGROUND

It has been well accepted that glycans present in schistosomes are highly antigenic. However, it is not clear what kind of worm glycans can affect the infected host to mount IgG responses and whether mounted anti-glycan IgG responses are protective.

METHODS

The contribution of antigenicity by glycans was measured by using competitive ELISA assay in sera from infected mice and humans. Monoclonal antibodies towards soluble Schistosoma japonicum egg antigens (SjEA) were generated from SjEA immunizated mice. The expression of glycans on surfaces of cercaria or young worm and their distributions were examined by immunofluorescence assay. The protective roles of glycans-specific mAbs were assayed by determination of the worm and egg burden in infected mice.

RESULTS

Both periodate-resistant glycans and periodate-sensitive glycans are antigenic in schistosome infections. When monoclonal antibodies against either periodate-sensitive or periodate-resistant glycans were administered prior to schistosome infections in mice, both kinds of anti-glycan antibodies were found to successfully provide protective immunity to infected mice.

CONCLUSIONS

Both periodate-resistant and periodate-sensitive glycans are antigenic, and dominant anti-glycan IgG responses can play important roles in protective immunity in schistosome infected hosts.

P2Y12 expression and function in alternatively activated human microglia

Objective:

To investigate and measure the functional significance of altered P2Y12 expression in the context of human microglia activation.

Methods:

We performed in vitro and in situ experiments to measure how P2Y12 expression can influence disease-relevant functional properties of classically activated (M1) and alternatively activated (M2) human microglia in the inflamed brain.

Results:

We demonstrated that compared to resting and classically activated (M1) human microglia, P2Y12 expression is increased under alternatively activated (M2) conditions. In response to ADP, the endogenous ligand of P2Y12, M2 microglia have increased ligand-mediated calcium responses, which are blocked by selective P2Y12 antagonism. P2Y12 antagonism was also shown to decrease migratory and inflammatory responses in human microglia upon exposure to nucleotides that are released during CNS injury; no effects were observed in human monocytes or macrophages. In situ experiments confirm that P2Y12 is selectively expressed on human microglia and elevated under neuropathologic conditions that promote T_h2 responses, such as parasitic CNS infection.

Conclusion:

These findings provide insight into the roles of M2 microglia in the context of neuroinflammation and suggest a mechanism to selectively target a functionally unique population of myeloid cells in the CNS.

An association of Aquaporin-4 with the immunoregulation of liver pathology in mice infected with Schistosoma japonicum

Background

Schistosomiasis is a chronic parasitic disease that affects approximately 200 million people. In Schistosomiasis japonica and mansoni, parasite eggs were trapped in host liver and stimulated the CD4⁺T cell responses to regulate the formation of the granulomas. Subsequently, excessive granulomatous response in some heavily, and/or repeatedly infected individuals could result in chronic liver fibrosis and circulatory impairment. Thus, elucidation of the mechanisms of these responses will not only provide more information to better understand the mechanisms of the immunoregulation in schistosomiasis, but also help to design new therapies to control granuloma-associated immunopathology. The role of aquaporin-4 (AQP4) in water transport has been extensively investigated in the central nervous system (CNS). Recently, studies have shown that AQP4 expresses in immune system and lack of AQP4 in mice results in significantly less CD4⁺CD25⁺ T regulatory cells (Treg cells) under physiological condition, one of the subpopulations of CD4⁺T cells which restrains immunopathology in hosts with schistosomiasis. However, little information exists regarding the contribution of AQP4 to the immune regulation in schistosome infection.

Methods

The liver granulomatous response in S. japonicum-infected AQP4 knockout (KO) mice and its wild-type (WT) littermates were detected by staining liver sections with hematoxylin and eosin. The generation of various CD4⁺ T subsets, including Th1, Th2, Th17, and Treg cells were analyzed by flow cytometry. In addition, the levels of total IgG, IgG1, IgG2a in serum of infected mice were detected by ELISA assay.

Results

Our results showed an enhanced granulomatous response with increased accumulation of eosinophils and macrophages around eggs in the liver of AQP4 KO mice with Schistosomiasis japonica. In addition, our study demonstrated enhanced Th2 but reduced Th1 and Treg cells generation in AQP4 KO mice with Schistosomiasis japonica, which may, at least partly, account for the enhancement of the liver granuloma formation.

Conclusion

Our study for the first time provides evidences that AQP4 has an association with the immunoregulation of the liver granuloma formation, which may confer a new option for schistosomiasis treatment.

Parasitic antigens alter macrophage polarization during Schistosoma japonicum infection in mice

Background

Schistosome eggs are trapped in host liver and elicit severe hepatic granulomatous inflammation, which can lead to periportal fibrosis, portal hypertension, hemorrhage, or even death in the host. It was reported that the macrophage plays an important role in host immune responses to schistosome infection. Nitric oxide (NO) produced by classically activated macrophages (M1 macrophages) is cytotoxic to schistosomula and can prevent hepatic schistosomal fibrosis, while arginase-1 (Arg-1) expressed by alternatively activated macrophages (M2 macrophages) promotes hepatic schistosomal fibrosis. However, the dynamics of macrophage polarization, as well as the possible factors that regulate macrophage polarization, during schistosome infection remain unclear.

Methods

We first analyzed M1 and M2-phenotypic markers of peritoneal macrophages from mice infected with Schistosoma japonicum (S. japonicum) at indicated time points using flow cytometry (FCM) analysis and real-time PCR. Then we treated peritoneal macrophages from normal mice with schistosome worm antigen (SWA) or schistosome soluble egg antigen (SEA) and determined M1 and M2-phenotypic markers, in order to identify macrophage polarization in responding to schistosomal antigens.

Results

In this study, we showed that macrophages were preferentially differentiated into the M1 subtype during the acute stage of S. japonicum infection. However, the level of M1 macrophages decreased and M2 macrophages significantly increased during the chronic stage of infection. Furthermore, we showed that SWA favors the generation of M1 macrophages, whereas SEA preferentially promotes M2-polarized phenotype.

Conclusion

These findings not only reveal the parasite antigen-driven dynamic changes in macrophage polarization, but also suggest that manipulation of macrophage polarization may be of therapeutic benefit in controlling excessive hepatic granulomas and fibrosis in the host with schistosomiasis.