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

Although the functions of programmed death-1 (PD-1) on αß 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.

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.

[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.

TLR7 modulates extramedullary splenic erythropoiesis in P. yoelii NSM-infected mice through the regulation of iron metabolism of macrophages with IFN-γ.

Splenomegaly is a prominent clinical manifestation of malaria and the causes remain incompletely clear. Anemia is induced in malaria and extramedullary splenic erythropoiesis is compensation for the loss of erythrocytes. However, the regulation of extramedullary splenic erythropoiesis in malaria is unknown. An inflammatory response could facilitate extramedullary splenic erythropoiesis in the settings of infection and inflammation. Here, when mice were infected with rodent parasites, Plasmodium yoelii NSM, TLR7 expression in splenocytes was increased. To explore the roles of TLR7 in splenic erythropoiesis, we infected wild-type and TLR7 -/- C57BL/6 mice with P. yoelii NSM and found that the development of splenic erythroid progenitor cells was impeded in TLR7 -/- mice. Contrarily, the treatment of the TLR7 agonist, R848, promoted extramedullary splenic erythropoiesis in wild-type infected mice, which highlights the implication of TLR7 on splenic erythropoiesis. Then, we found that TLR7 promoted the production of IFN-γ that could enhance phagocytosis of infected erythrocytes by RAW264.7. After phagocytosis of infected erythrocytes, the iron metabolism of RAW264.7 was upregulated, evidenced by higher iron content and expression of Hmox1 and Slc40a1. Additionally, the neutralization of IFN-γ impeded the extramedullary splenic erythropoiesis modestly and reduced the iron accumulation in the spleen of infected mice. In conclusion, TLR7 promoted extramedullary splenic erythropoiesis in P. yoelii NSM-infected mice. TLR7 enhanced the production of IFN-γ, and IFN-γ promoted phagocytosis of infected erythrocytes and the iron metabolism of macrophages in vitro, which may be related to the regulation of extramedullary splenic erythropoiesis by TLR7.

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.

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.

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.

Epidemiological investigation and intergenerational clinical characteristics of 24 coronavirus disease patients associated with a supermarket cluster: a retrospective study.

BACKGROUND: In view of the ongoing coronavirus disease (COVID-19) pandemic, it remains unclear whether the severity of illness and time interval from symptom onset to release from quarantine differ between cases that originated from clusters and cases reported in other areas. This study aimed to assess epidemiological and intergenerational clinical characteristics of COVID-19 patients associated with cluster outbreaks to provide valuable data for the prevention and control of COVID-19. METHODS: We identified the first employee with COVID-19 at a supermarket and screened the close contacts of this index patient. Confirmed cases were divided into two groups according to the generation (first generation comprising supermarket employees [group A] and second or third generations comprising family members or friends of the supermarket employees [group B]). The epidemiological and clinical characteristics of the two groups were retrospectively compared. RESULTS: A total of 8437 people were screened, and 24 COVID-19 patients were identified. Seven patients (29.2%) were asymptomatic; three patients were responsible for six symptomatic cases. The interval from the confirmation of the first case to symptom onset in symptomatic patients was 5-11 days. The clinical manifestations of symptomatic patients upon admission were non-specific. All patients (including the seven asymptomatic patients) were admitted based on chest computed tomography features indicative of pneumonia. There were 11 cases in group A (first generation) and 13 cases in group B (second generation, 11 cases; third generation, 2 cases), with no significant differences in clinical and epidemiological characteristics between the two groups, except for sex, duration from symptom onset to hospitalization, and underlying disease (P > 0.05). CONCLUSIONS: For cluster outbreaks, it is important to comprehensively screen close the contacts of the index patient. Special attention should be paid to asymptomatic cases. The clinical management of cluster patients is similar to that of other COVID-19 patients.

Clinical Characteristics and Reasons for Differences in Duration From Symptom Onset to Release From Quarantine Among Patients With COVID-19 in Liaocheng, China.

Objective: This study aimed to identify additional characteristics and features of coronavirus disease (COVID-19) by assessing the clinical courses among COVID-19 patients in a region outside Hubei province. Methods: We analyzed retrospective data regarding general characteristics, epidemiologic history, underlying chronic diseases, clinical symptoms and complications, chest computed tomography findings, biochemical monitoring, disease severity, treatments, and outcomes among 37 adult patients with COVID-19. According to the duration from symptom onset to release from quarantine, the patients were divided into the ≤20 and >20-day groups, and the similarities and differences between them were compared. Results: Among the 37 patients, five had mild disease, 30 had moderate disease, one had severe disease, and one was critically ill. All of the patients were released from quarantine, and no mortality was observed. The average duration from symptom onset to release from quarantine was 20.2 ± 6.6 days. The average duration from symptom onset to hospitalization was 4.1 ± 3.7 days, and the patients were hospitalized for an average of 16.1 ± 6.2 days. The average age was 44.3 ± 1.67 years, and 78.4% of cases were caused by exposure to a patient with confirmed disease or the workplace of a patient with confirmed disease. The main symptoms were cough (67.6%), fever (62.2%), shortness of breath (32.4%), fatigue (24.3%), sore throat (21.6%), vomiting, and diarrhea (21.6%). White blood cell count was decreased in 27.0% of patients, and lymphocyte count was decreased in 62.2% of the patients, among whom 43.5% patients had counts of ≤0.6 × 109/L. On admission, 86.5% of patients showed pneumonia in chest CT scans, including some asymptomatic patients, while 68.8% of patients showed bilateral infiltration. In the >20-day group, the average age was 49.9 ± 1.38 years, and the average duration from symptom onset to hospitalization was 5.5 ± 3.9 days. Compared with the ≤20-day group, patients in the >20-day group were older and the duration was longer (P < 0.05). All of the seven asymptomatic patients belonged to the ≤20-day group. When the 37 patients were released from quarantine, the white blood cell count of 16.2% of the patients was <4.0 × 109/L, the lymphocyte count of 59.5% of the patients was <1.1 × 109/L, and the absolute counts of white blood cells and lymphocytes were 5.02 ± 1.34 × 109/L and 1.03 ± 0.34 × 109/L, respectively, compared with those recorded on admission (P > 0.05). Conclusion: The majority of COVID-19 cases in the study area were mild and moderate, with good clinical outcomes. There were some special characteristics in the clinical course. The reasons for differences in the duration from symptom onset to release from quarantine were complex. There was no significant change in the number of granulocytes at the time of release from quarantine compared to that at the time of admission.