Immune response of γδT cells in Schistosome japonicum-infected C57BL/6 mouse liver

Characteristics of splenic PD-1+ γδT cells in Plasmodium yoelii nigeriensis infection

Although the functions of programmed death-1 (PD-1) on αβ T cells have been extensively reported, a role for PD-1 in regulating γδT cell function is only beginning to emerge. Here, we investigated the phenotypic and functional characteristics of PD-1-expressing γδT cells, and the molecular mechanism was also explored in the Plasmodium yoelii nigeriensis (P. yoelii NSM)-infected mice. Flow cytometry and single-cell RNA sequencing (scRNA-seq) were performed. An inverse agonist of RORα, SR3335, was used to investigate the role of RORα in regulating PD-1+ γδT cells. The results indicated that γδT cells continuously upregulated PD-1 expression during the infection period. Higher levels of CD94, IL-10, CX3CR1, and CD107a; and lower levels of CD25, CD69, and CD127 were found in PD-1+ γδT cells from infected mice than in PD-1- γδT cells. Furthermore, GO enrichment analysis revealed that the marker genes in PD-1+ γδT cells were involved in autophagy and processes utilizing autophagic mechanisms. ScRNA-seq results showed that RORα was increased significantly in PD-1+ γδT cells. GSEA identified that RORα was mainly involved in the regulation of I-kappaB kinase/NF-κB signaling and the positive regulation of cytokine production. Consistent with this, PD-1-expressing γδT cells upregulated RORα following Plasmodium yoelii infection. Additionally, in vitro studies revealed that higher levels of p-p65 were found in PD-1+ γδT cells after treatment with a RORα selective synthetic inhibitor. Collectively, these data suggest that RORα-mediated attenuation of NF-κB signaling may be fundamental for PD-1-expressing γδT cells to modulate host immune responses in the spleen of Plasmodium yoelii nigeriensis-infected C57BL/6 mice, and it requires further investigation.

Evaluation of the TLR3 involvement during Schistosoma japonicum-induced pathology

BACKGROUND

Despite the functions of TLRs in the parasitic infections have been extensively reported, few studies have addressed the role of TLR3 in the immune response to Schistosoma japonicum infections. The aim of this study was to investigate the properties of TLR3 in the liver of C57BL/6 mice infected by S. japonicum.

METHODS

The production of TLR3+ cells in CD4+T cells (CD4+CD3+), CD8+T cells (CD8+CD3+), γδT cells (γδTCR+CD3+), NKT cells (NK1.1+CD3+), B cells (CD19+CD3-), NK (NK1.1-CD3+) cells, MDSC (CD11b+Gr1+), macrophages (CD11b+F4/80+), DCs (CD11c+CD11b+) and neutrophils (CD11b+ Ly6g+) were assessed by flow cytometry. Sections of the liver were examined by haematoxylin and eosin staining in order to measure the area of granulomas. Hematological parameters including white blood cell (WBC), red blood cell (RBC), platelet (PLT) and hemoglobin (HGB) were analyzed. The levels of ALT and AST in the serum were measured using biochemical kits. The relative titers of anti-SEA IgG and anti-SEA IgM in the serum were measured by enzyme-linked immunosorbent assay (ELISA). CD25, CD69, CD314 and CD94 molecules were detected by flow cytometry.

RESULTS

Flow cytometry results showed that the expression of TLR3 increased significantly after S. japonicum infection (P < 0.05). Hepatic myeloid and lymphoid cells could express TLR3, and the percentages of TLR3-expressing MDSC, macrophages and neutrophils were increased after infection. Knocking out TLR3 ameliorated the damage and decreased infiltration of inflammatory cells in infected C57BL/6 mouse livers.,The number of WBC was significantly reduced in TLR3 KO-infected mice compared to WT-infected mice (P < 0.01), but the levels of RBC, platelet and HGB were significantly increased in KO infected mice. Moreover, the relative titers of anti-SEA IgG and anti-SEA IgM in the serum of infected KO mice were statistically decreased compared with the infected WT mice. We also compared the activation-associated molecules expression between S.japonicum-infected WT and TLR3 KO mice.

CONCLUSIONS

Taken together, our data indicated that TLR3 played potential roles in the context of S. japonicum infection and it may accelerate the progression of S. japonicum-associated liver pathology.

Characteristics of γδTCR on myeloid cells from C57BL/6 mice with Plasmodium yoelii nigeriensis infection

Recently, there is a paucity of studies focus on the characteristics of myeloid cells which expressed γδTCR. The aim of this study was to observe the properties of γδTCR-expressing myeloid cells in the spleen of C57BL/6 mice infected by P. yoelii nigeriensis NSM. Haematoxylin-eosin (HE) staining was used to observe pathological changes in the spleens from infected mice. The differentially expressed genes (DEGs) between the infection and control groups were analyzed by RNA sequencing (RNA -seq). Flow cytometry (FCM) was used to evaluate the frequency of γδTCR⁺ cells and the characteristics of γδTCR⁺ cells in P. yoelii nigeriensis NSM-infected mice. Obvious infiltration of inflammatory were observed in the spleens from infected C57BL/6 mouse. The proportions of γδTCR⁺ cells and CD11b⁺ γδTCR⁺ cells from infected group were higher than that from normal group. CD11b⁺ γδTCR⁺ cells expressed high levels of activated-mediated genes and inflammatory-mediated genes. The heterogeneous pathway activities among CD11b⁺ γδTCR⁺ cells from normal and infected group were characterized. The oxidative phosphorylation, respiratory electron transport chain and leukocyte activation involved in immune response pathways were up-regulated, while the alpha-beta T cell activation and myeloid leukocyte migration pathways were down-regulated in infected mice. Importantly, Ly6c2 was higher expressed in CD11b⁺ γδTCR⁺ cells than Ly6g. Consistent with it, flow cytometry results revealed that a subset of Ly6C⁺ cells was higher than Ly6G⁺ cells in the spleen. Taken together, our data suggest the existence of a population of γδTCR-expressing myeloid cells and they might be multifunctional cells, which play a role in couse of Plasmodium infection.

Higher frequency of circulating Vδ1 γδT cells in patients with advanced schistosomiasis

Gamma‐delta (γδ) T cells are the bridge between natural and adaptive immunity. In the present study, peripheral blood was collected from 13 patients with advanced schistosomiasis (schistosomiasis group) and 13 uninfected people (control group) to investigate the γδ T cells and their subtypes in human schistosomiasis. Compared with the control group, the proportion of Vδ1 cells and CD27⁺Vδ1⁺ cells in the schistosomiasis group increased significantly, while CD27⁻ cells and CD27⁻Vδ1⁻ cells decreased. Only the level of IL‐17A differed between the groups, being significantly decreased in the schistosomiasis group. In the schistosomiasis group, there were no correlations between the liver fibrosis and subsets of γδ T cells, or the level of cytokines. Additionally, the level of IL‐17A correlated positively with the proportion of CD27⁻ Vδ1⁻ cells. Thus, there was a higher frequency of circulating Vδ1 γδT cells in patients with advanced schistosomiasis. The decreased IL‐17A might be related to the reduction in CD27⁻Vδ1⁻ cell.

Expression of TLR2, TLR3, TLR4, and TLR7 on pulmonary lymphocytes of Schistosoma japonicum-infected C57BL/6 mice

Despite the paramount role of TLRs in the induction of innate immune and inflammatory responses, there is a paucity of studies on the role of TLRs in Schistosoma japonicum infection. Here, we observed obvious infiltration of inflammatory cells in S. japonicum-infected C57BL/6 mouse lungs. Expression and release of IFN-γ, IL-4, and IL-17 were significantly higher in pulmonary lymphocytes from infected mice compared with control mice in response to anti-CD3 plus anti-CD28 mAbs. Higher percentages of TLR2, TLR3, TLR4, and TLR7 were expressed on such lymphocytes, and the TLR agonists PGN, Poly I:C, LPS, and R848 induced a higher level of IFN-γ. However, a higher level of IL-4 was found in the supernatant of pulmonary lymphocytes from infected mice stimulated by these TLR agonists plus CD3 Ab. Only R848 plus anti-CD3 mAb could induce a higher level of IFN-γ in such lymphocytes. TLR expressions were then compared on different pulmonary lymphocytes after infection, including T cells, B cells, NK cells, NKT cells, and γδT cells. The expression levels of TLR3 on T cells, B cells, NK cells, and γδT cells were increased in the lungs after infection. NK cells also expressed higher levels of TLR4 after infection of control mice. Collectively, these findings highlight the potential role of TLR expression in the context of S. japonicum infection.