Immunological characteristics of CD103+CD8+ Tc cells in the liver of C57BL/6 mouse infected with plasmodium NSM.

CD103 is an important marker of tissue-resident memory T cells (TRM) which play important roles in fighting against infection. However, the immunological characteristics of CD103+ T cells are not thoroughly elucidated in the liver of mouse infected with Plasmodium. Six- to eight-week-old C57BL/6 mice were infected with Plasmodium yoelii nigeriensis NSM. Mice were sacrificed on 12-16 days after infection and the livers were picked out. Sections of the livers were stained, and serum aspartate aminotransferase (AST) and alanine transaminase (ALT) levels were measured. Moreover, lymphocytes in the liver were isolated, and the expression of CD103 was determined by using qPCR. The percentage of CD103 on different immune cell populations was dynamically observed by using flow cytometry (FCM). In addition, the phenotype and cytokine production characteristics of CD103+CD8+ Tc cell were analyzed by using flow cytometry, respectively. Erythrocyte stage plasmodium infection could result in severe hepatic damage, a widespread inflammatory response and the decrease of CD103 expression on hepatic immune cells. Only CD8+ Tc and γδT cells expressed higher levels of CD103 in the uninfected state.CD103 expression in CD8+ Tc cells significantly decreased after infection. Compared to that of CD103- CD8+ Tc cells, CD103+ CD8+ Tc cells from the infected mice expressed lower level of CD69, higher level of CD62L, and secreted more IL-4, IL-10, IL-17, and secreted less IFN-γ. CD103+CD8+ Tc cells might mediate the hepatic immune response by secreting IL-4, IL-10, and IL-17 except IFN-γ in the mice infected with the erythrocytic phase plasmodium, which could be involved in the pathogenesis of severe liver damage resulted from the erythrocytic phase plasmodium yoelii nigeriensis NSM infection.

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.

[The number of TIGIT+CD8+ T cells increases but their cytokine secretion decreases in the lungs of Plasmodium yoelii infected mice].

Objective To investigate the effect of T cell immunoreceptor with Ig and ITIM domains (TIGIT) on the function of CD8+ T cells in the lungs of Plasmodium infected mice. Methods The lungs of the mice infected with Plasmodium yoelii were isolated, weighed and photographed after 12 days' infection. After dissolution, lung lymphocytes were isolated, counted and stained, and then the contents of CD8+ and TIGIT+CD8+ T cells were detected by flow cytometry. The expressions of L selectin (CD62L), CD69, programmed death 1 (PD-1), CD25, and C-X3-C motif chemokine receptor 1 (CX3CR1) on TIGIT+CD8+ T cells were detected by flow cytometry. After stimulation with phorbol 12-myristate 13-acetate (PMA) and ionomycin, the ability of TIGIT+CD8+T cells to secrete interferon γ(IFN-γ), interleukin 21 (IL-21), IL-4, IL-17, and IL-10 was detected. Results The body mass of mice with Plasmodium infection was reduced. The lungs became darker, and the ratio of the lung mass to body mass was significantly increased. Compared with the normal mice, the percentages and absolute quantity of CD8+ and TIGIT+CD8+ T cells in the lungs of the infected mice were significantly increased. The percentage of TIGIT+CD8+ T cells expressing CD62L in the infected group was significantly lower, while the percentage of the CD69, PD-1, and CX3CR1 cells were significantly higher than that of TIGIT+CD8+ T cells from the normal mice. The percentages of TIGIT+CD8+ T cells secreting IL-21, IL-4, IL-17 and IL-10 cells in the infected group were significantly lower. Conclusion The lung lesions from mice with Plasmodium infection are obvious, the numbers of TIGIT+CD8+ T cells increase, and these cells express a variety of activation-related molecules, but the ability to secrete cytokines is reduced.

Characteristics of Th9 cells in Schistosoma japonicum-infected C57BL/6 mouse mesenteric lymph node.

Interleukin 9 (IL-9) is an effective cytokine secreted by newly defined Th9 cells, which is involved in allergic and infectious diseases. In this study, lymphocytes were isolated from mesenteric lymph node (MLN), spleen, liver, lung, and Peyer's patches (PP) of C57BL/6 mice 5-6 weeks after S. japonicum infection, intracellular cytokine staining was done to detect the percentage of IL-9-producing CD4+ T cells. The qPCR and ELISA were used to verify the content of IL-9 in MLN. The population of IL-9-producing lymphocyte subset was identified by FACS. In addition, the dynamic changes and cytokine profiles of Th9 cells in the MLN of infected mice were detected by FACS. ELISA was used to detect IL-9 induced by soluble egg antigen (SEA) from isolated lymphocytes in mouse MLN. The results showed that the percentage of IL-9-secreting Th9 cells in the MLN of the infected mouse was higher than that in the spleen, liver, lung, or PP. Though CD8+ Tc cells, NKT cells, and γδT cells could secrete IL-9, CD4+ Th cells were the main source of IL-9 in S. japonicum-infected C57BL/6 mice (P < 0.05). The percentage of Th9 cells in MLN of infected mouse increased from week 3-4, and reached a peak at week 5-6, then began to decrease from week 7-8 (P < 0.05). Moreover, Th9 cells could also secrete a small amount of IL-4, IFN-γ, IL-5, and IL-10. Our results suggested a higher percentage of Th9 cells was induced in the MLN of S. japonicum-infected mice, which might play an important role in the early stage of S. japonicum-induced disease.

PD-1+ CD4 T cell immune response is mediated by HIF-1α/NFATc1 pathway after P. yoelii infection.

The morbidity and mortality of malaria are still high. Programmed cell death-1(PD-1) is an important co-inhibitory factor and CD8 T cells with PD-1 were reported to be exhausted cells. It remains unknown what the role of CD4 T cells expressing PD-1 is and what the upstream regulating molecules of PD-1 in CD4 T cells are. The C57BL/6 mice were injected with Plasmodium yoelii (P. yoelii) in this study. Expressions of PD-1, activation markers, and cytokines were tested. The differentially expressed genes between PD-1+/- CD4 T cells were detected by microarray sequencing. Western blot, chromatin immunoprecipitation (ChIP), siRNA, hypoxia inducible factor-1α (HIF-1α) inducer and inhibitor were used to explore PD-1's upstream molecules, respectively. The proportions of PD-1+ CD4 T cells increased post P. yoelii infection. PD-1+ CD4 T cells expressed more activated surface markers and could produce more cytokines. Nuclear factor of activated T cells 1 (NFATc1) was found to be a key transcription factor to induce PD-1 expression after infection. Both the inducer and the inhibitor of HIF-1α could change the expressions of NFATc1 and PD-1 in vivo and in vitro, respectively. Taken together, P. yoelii infection induced NFATc1 expression by HIF-1α. The highly expressed NFATc1 entered the nucleus and initiated PD-1 expression. PD-1+ CD4 T cells appeared to be more activated and could secrete more cytokines to regulate the host's immune responses against malaria.

Roles of TLR7 in Schistosoma japonicum Infection-Induced Hepatic Pathological Changes in C57BL/6 Mice.

S. japonicum infection can induce granulomatous inflammation in the liver of the host. Granulomatous inflammation limits the spread of infection and plays a role in host protection. Toll-like receptor 7 (TLR7) is an endosomal TLR that recognizes single-stranded RNA (ssRNA). In this study, the role of TLR7 in S. japonicum infection-induced hepatitis was investigated in both normal and TLR7 knockout (KO) C57BL/6 mice. The results indicated that TLR7 KO could aggravate S. japonicum infection-induced damage in the body, with less granuloma formation in the tissue, lower WBCs in blood, and decreased ALT and AST in the serum. Then, the expression of TLR7 was detected in isolated hepatic lymphocytes. The results indicated that the percentage of TLR7+ cells was increased in the infected mice. Hepatic macrophages, DCs, and B cells could express TLR7, and most of the TLR7-expressing cells in the liver of infected mice were macrophages. The percentage of TLR7-expressing macrophages was also increased after infection. Moreover, macrophages, T cells, and B cells showed significant changes in the counts, activation-associated molecule expression, and cytokine secretion between S. japonicum-infected WT and TLR7 KO mice. Altogether, this study indicated that TLR7 could delay the progression of S. japonicum infection-induced hepatitis mainly through macrophages. DCs, B cells, and T cells were involved in the TLR7-mediated immune response.

Properties and Roles of γδT Cells in Plasmodium yoelii nigeriensis NSM Infected C57BL/6 Mice.

BACKGROUND: Many kinds of immune cells are involved in malaria infection. γδT cells represent a special type of immune cell between natural and adaptive immune cells that play critical roles in anti-parasite infection. METHODS: In this study, malaria infection model was constructed. Distribution of γδT cells in various immune organs and dynamic changes of γδT cells in the spleens of C57BL/6 mice after infection were detected by flow cytometry. And activation status of γδT cells was detected by flow cytometry. Then γδT cells in naive and infected mice were sorted and performed single-cell RNA sequencing (scRNA-seq). Finally, γδTCR KO mice model was constructed and the effect of γδT cell depletion on mouse T and B cell immunity against Plasmodium infection was explored. RESULTS: Here, splenic γδT cells were found to increase significantly on day 14 after Plasmodium yoelii nigeriensis NSM infection in C57BL/6 mice. Higher level of CD69, ICOS and PD-1, lower level of CD62L, and decreased IFN-γ producing after stimulation by PMA and ionomycin were found in γδT cells from infected mice, compared with naive mice. Moreover, 11 clusters were identified in γδT cells by scRNA-seq based t-SNE analysis. Cluster 4, 5, and 7 in γδT cells from infected mice were found the expression of numerous genes involved in immune response. In the same time, the GO enrichment analysis revealed that the marker genes in the infection group were involved in innate and adaptive immunity, pathway enrichment analysis identified the marker genes in the infected group shared many key signalling molecules with other cells or against pathogen infection. Furthermore, increased parasitaemia, decreased numbers of RBC and PLT, and increased numbers of WBC were found in the peripheral blood from γδTCR KO mice. Finally, lower IFN-γ and CD69 expressing CD4+ and CD8+ T cells, lower B cell percentage and numbers, and less CD69 expressing B cells were found in the spleen from γδTCR KO infected mice, and lower levels of IgG and IgM antibodies in the serum were also observed than WT mice. CONCLUSIONS: Overall, this study demonstrates the diversity of γδT cells in the spleen of Plasmodium yoelii nigeriensis NSM infected C57BL/6 mice at both the protein and RNA levels, and suggests that the expansion of γδT cells in cluster 4, 5 and 7 could promote both cellular and humoral immune responses.

Ikzf2 Regulates the Development of ICOS+ Th Cells to Mediate Immune Response in the Spleen of S. japonicum-Infected C57BL/6 Mice.

Background: Th cells (helper T cells) have multiple functions in Schistosoma japonicum (S. japonicum) infection. Inducible co-stimulator (ICOS) is induced and expressed in activated T lymphocytes, which enhances the development of B cells and antibody production through the ICOS/ICOSL pathway. It remains unclear about the role and possible regulating mechanism of ICOS+ Th cells in the spleen of S. japonicum-infected C57BL/6 mice. Methods: C57BL/6 mice were infected with cercariae of S. japonicum through the abdomen. The expression of ICOS, activation markers, and the cytokine production on CD4+ ICOS+ Th cells were detected by flow cytometry (FCM) and quantitative real-time PCR (qRT-PCR). Moreover, the differentially expressed gene data of ICOS+ and ICOS- Th cells from the spleen of infected mice were obtained by mRNA sequencing. Besides, Western blot and chromatin immunoprecipitation (ChIP) were used to explore the role of Ikzf2 on ICOS expression. Results: After S. japonicum infection, the expression of ICOS molecules gradually increased in splenic lymphocytes, especially in Th cells (P < 0.01). Compared with ICOS- Th cells, more ICOS+ Th cells expressed CD69, CD25, CXCR5, and CD40L (P < 0.05), while less of them expressed CD62L (P < 0.05). Also, ICOS+ Th cells expressed more cytokines, such as IFN-γ, IL-4, IL-10, IL-2, and IL-21 (P < 0.05). RNA sequencing results showed that many transcription factors were increased significantly in ICOS+ Th cells, especially Ikzf2 (P < 0.05). And then, the expression of Ikzf2 was verified to be significantly increased and mainly located in the nuclear of ICOS+ Th cells. Finally, ChIP experiments and dual-luciferase reporter assay confirmed that Ikzf2 could directly bind to the ICOS promoter in Th cells. Conclusion: In this study, ICOS+ Th cells were found to play an important role in S. japonicum infection to induce immune response in the spleen of C57BL/6 mice. Additionally, Ikzf2 was found to be one important transcription factor that could regulate the expression of ICOS in the spleen of S. japonicum-infected C57BL/6 mice.

TLR7 modulating B-cell immune responses in the spleen of C57BL/6 mice infected with Schistosoma japonicum.

B cells played an important role in Schistosoma infection-induced diseases. TLR7 is an intracellular member of the innate immune receptor. The role of TLR7 on B cells mediated immune response is still unclear. Here, C57BL/6 mice were percutaneously infected by S. japonicum for 5-6 weeks. The percentages and numbers of B cells increased in the infected mice (p < 0.05), and many activation and function associated molecules were also changed on B cells. More splenic cells of the infected mice expressed TLR7, and B cells were served as the main cell population. Moreover, a lower level of soluble egg antigen (SEA) specific antibody and less activation associated molecules were found on the surface of splenic B cells from S. japonicum infected TLR7 gene knockout (TLR7 KO) mice compared to infected wild type (WT) mice (p < 0.05). Additionally, SEA showed a little higher ability in inducing the activation of B cells from naive WT mice than TLR7 KO mice (p < 0.05). Finally, the effects of TLR7 on B cells are dependent on the activation of NF-κB p65. Altogether, TLR7 was found modulating the splenic B cell responses in S. japonicum infected C57BL/6 mice.