The Inflammatory Factors Associated with Disease Severity to Predict COVID-19 Progression.

Coronavirus disease 2019 (COVID-19) is associated with immune dysregulation and cytokine storm. Exploring the immune-inflammatory characteristics of COVID-19 patients is essential to reveal pathogenesis and predict progression. In this study, COVID-19 patients showed decreased CD3+, CD4+, and CD8+ T cells but increased neutrophils in circulation, exhibiting upregulated neutrophil-to-lymphocyte and neutrophil-to-CD8+ T cell ratio. IL-6, TNF-α, IL-1ß, IL-18, IL-12/IL-23p40, IL-10, Tim-3, IL-8, neutrophil extracellular trap-related proteinase 3, and S100A8/A9 were elevated, whereas IFN-γ and C-type lectin domain family 9 member A (clec9A) were decreased in COVID-19 patients compared with healthy controls. When compared with influenza patients, the expressions of TNF-α, IL-18, IL-12/IL-23p40, IL-8, S100A8/A9 and Tim-3 were significantly increased in critical COVID-19 patients, and carcinoembryonic Ag, IL-8, and S100A8/A9 could serve as clinically available hematologic indexes for identifying COVID-19 from influenza. Moreover, IL-6, IL-8, IL-1ß, TNF-α, proteinase 3, and S100A8/A9 were increased in bronchoalveolar lavage fluid of severe/critical patients compared with moderate patients, despite decreased CD4+ T cells, CD8+ T cells, B cells, and NK cells. Interestingly, bronchoalveolar IL-6, carcinoembryonic Ag, IL-8, S100A8/A9, and proteinase 3 were found to be predictive of COVID-19 severity and may serve as potential biomarkers for predicting COVID-19 progression and potential targets in therapeutic intervention of COVID-19.

Increased expression of Clec9A on cDC1s associated with cytotoxic CD8+ T cell response in COPD.

Although C-type lectin domain family 9A (Clec9A) on conventional type 1 dendritic cells (cDC1s) plays a critical role in cytotoxic CD8+ T cell response in cancers and viral infections, its role in chronic obstructive pulmonary disease (COPD) is unknown. We measured the expression of Clec9A in sera, bronchoalveolar lavage fluid (BALF), and peripheral blood mononuclear cells (PBMCs) from controls and COPD patients. The percentages of Clec9A+ DC and cytotoxic CD8+ T cell in the BALF were determined by flow cytometry between patients with COPD and non-obstructive chronic bronchitis (NOCB). Compared with healthy individuals, the serum levels of Clec9A were increased at different stages of COPD patients, and the mRNA and protein levels of Clec9A were both increased in COPD patients at GOLD stages III-IV. The percentage of Clec9A+ DCs was also increased in the BALF of COPD patients compared with NOCB patients. Moreover, enhanced Clec9A+ DCs recruitment was positively correlated with cytotoxic CD8+ T cell response in the BALF of COPD patients. This study suggests that Clec9A+ DCs participate in the CD8+ T cell-mediated chronic airway inflammation in COPD.

TIM-3 regulates the NETs-mediated dendritic cell activation in myeloperoxidase-ANCA-associated vasculitis.

OBJECTIVES: T cell immunoglobulin and mucin domain 3 (TIM-3) has been reported as an important regulatory molecule on T cells and plays a pivotal role in autoimmune diseases, but the impact on dendritic cells (DCs) is poorly explored. The formation of neutrophil extracellular traps (NETs) is considered as strongly implicated in the pathogenesis of autoimmune diseases, such as in myeloperoxidase-antineutrophil cytoplasmic autoantibody associated vasculitis (MPO-AAV). This study thus aimed to investigate the potential regulation roles of TIM-3 in the regulation of NETs-mediated DC activation in MPO-AAV. METHODS: Twenty untreated patients with MPO-AAV and 20 healthy controls were enrolled in this study. The expressions of TIM-3 and toll-like receptor 4 (TLR4) in peripheral blood dendritic cells were analysed by flow cytometry, and the release of NETs by neutrophils was evaluated by immunofluorescence. In animal experiments, we measured the DC activation markers after the stimulation of NETs. Furthermore, we detected the NETs-mediated DC activation after TIM-3 blockade. RESULTS: Here we found an increased spontaneous NET production in MPOAAV patients. We also revealed a markedly reduced expression of TIM-3 and an increased expression of TLR4 on DCs of active MPO-AAV patients. We found the NETs could induce the activation of DCs and promote Toll-like receptor 4 expression on DC surface. More interestingly, the blockade of TIM-3 could further enhance the NETs-mediated DC cytokine expression. CONCLUSIONS: Our results demonstrated DC surface TIM-3 plays an important role in maintaining the NETs mediated immune homeostasis in MPO-AAV, suggesting an important role in MPOAAV development.

Cryptococcus neoformans Infection Induces IL-17 Production by Promoting STAT3 Phosphorylation in CD4+ T Cells.

Cryptococcus neoformans infection in the central nervous system is a severe infectious disease with poor outcomes and high mortality. It has been estimated that there are 220,000 new cases each year. Over 90% of C. neoformans meningitis cases were diagnosed in AIDS patients with CD4+ T cell count <100 cells/µl; however, the mechanism of cryptococcal meningitis in patients with normal immune functions remains unclear. IL-17 is a pro-inflammatory cytokine and plays an important role in anti-fungal immunity. Here we report that significantly high levels of IL-17 were predominantly detected in the cerebrospinal fluid of patients with either AIDS- or non-AIDS-associated C. neoformans meningitis but not in patients with tuberculous meningitis or non-neurosyphilis. Antifungal therapy minimized the IL-17 level in the cerebrospinal fluid. An in vitro mechanistic study showed that C. neoformans stimulation of healthy peripheral blood mononuclear cells prompted IL-17 production, and CD4+ T cells were the predominant IL-17-producing cells. IL-17 production by C. neoformans stimulation was STAT3 signaling dependent. Inhibition of STAT3 phosphorylation attenuated the C. neoformans-mediated IL-17 expression. Our data highlighted the significance of CD4+ T cells in antifungal immunity and suggested IL-17 as a diagnostic biomarker of C. neoformans infection and STAT3 as a checkpoint for antifungal targeted therapies.

[Ageing down-modulates the immune responses to Schistosoma japonicum infection in mice].

OBJECTIVE: To investigate the effect of ageing on the immune responses against Schistosoma japonicum infection in mice. METHODS: Female BALB/c mice were divided into young group (2 months) and old group (18 months), each composed of 8 mice. Each mouse was percutaneously infected with 40 +/- 1 S. japonicum cercariae. At 6 weeks post-infection, the mice were sacrificed, and the spleens were removed and single-cell suspensions of splenocytes were prepared. Worms were perfused from hepatic portal system and counted. The number of eggs in the liver was determined after KOH digestion. Mean single-egg granulomas sizes were determined in stained histological sections. Splenocyte proliferation responses were analyzed by MTT colorimetry. Level of interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) in the splenocyte culture supernatants was determined by ELISA. RESULTS: The worm burden and egg per gram of liver in old mice [19.75 +/- 1.95, (1.59 +/- 1.05) x 10(4)] were significantly lower than that of young mice [26.00 +/- 2.42, (208 +/- 0.87) x 10(4)] (P < 0.05). The mean volume of single-egg granulomas of the livers in old mice [(30.13 +/- 10.97) x 10(3) mm3] was significantly lower than that of the young mice [(47.02 +/- 24.13) x l0(3) mm3] (P < 0.05). RESULTS: of T cell proliferation showed that the splenocytes had poorer immune reactivity to ConA in old mice (SI: 1.08 +/- 0.12) than that in young mice (SI: 131 +/- 0.14) (P < 0.05). Levels of IFN-gamma and IL-4 in the splenocyte culture supernatants [(24.05 +/- 6.24), (4.15 +/- 0.68) pg/ml] from old mice were lower than that of young mice [(34.25 +/- 869), (7125 +/- 0.83) pg/ml](P < 0.05). CONCLUSION: Ageing down-modulates the immune responses and the poorer immune reactivity might decrease pathological alterations in mice infected with Schistosoma japonicum.

[Purification of Toxoplasma gondii Tachyzoites with cellulose membrane filtration and preparation of soluble antigen].

20 ml peritoneal lavage fluid of mice infected with Toxoplasma gondii RH strain was diluted to 250 ml with sterilized physiological saline, and filtered through cellulose membrane filters (pore size: 5 microm). The filtrate was centrifuged at 1512 x g for 15 min, and the sediment was pure T. gondii tachyzoites which were then sonicated. The soluble antigen was prepared by centrifugation at 11200 x g for 30 min. Sera of T. gondii infected SD rat and normal SD rats were collected for immunodetection of soluble antigen. The specificity and valence of soluble antigen were detected with indirect ELISA. The mean removal rates of mouse leukocytes and erythrocytes were 99.9% and 80.3%, respectively, and recovery rate of tachyzoites was 71%. The soluble antigen was extracted from purified T. gondii (1.38 mg per mouse). Indirect ELISA showed that the lowest effective antigen concentration was 5 microg/ml.

Ghrelin protects human umbilical vein endothelial cells against high glucose-induced apoptosis via mTOR/P70S6K signaling pathway.

Ghrelin exhibits its biological effect through binding to the growth hormone secretagogue 1a receptor (GHS-R1a). Recently, it has been reported that ghrelin has an anti-apoptotic effect in several cell types. However, the molecule mechanisms underlying the anti-apoptotic effect of ghrelin remain poorly understood. In this study, we investigated the intracellular mechanisms responsible for anti-apoptotic effect of ghrelin on human umbilical vein endothelial cells (HUVEC). Treatment of HUVEC with ghrelin inhibited high glucose-induced cell apoptosis. Ghrelin stimulated the rapid phosphorylation of mammalian target of rapamycin (mTOR), P70S6K and S6. The GHS-R1a-specific antagonist [D-Lys3]-GHRP-6 abolished the anti-apoptotic effect and inhibited the activation of mTOR, P70S6K, S6 induced by ghrelin. Pretreatment of cells with specific inhibitor of mTOR blocked the anti-apoptotic effect of ghrelin. In addition, ghrelin protected HUVECs against high glucose induced apoptosis by increasing Bcl-2/Bax ratio. Taken together, our results demonstrate that ghrelin produces a protective effect on HUVECs through activating GHS-R1a and mTOR/P70S6K signaling pathway mediates the effect of ghrelin. These observations suggest that ghrelin may act as a survival factor in preventing HUVECs apoptosis caused by high glucose.

[Dynamic expressions of IL-17 and IL-23 in mice infected with Schistosoma japonicum].

OBJECTIVE: To investigate the dynamic expressions of IL-17 and IL-23 in mice with Schistosoma japonicum infection. METHOD: A murine model of the infection of S. japonicum was established. The suspension of spleen cells incubated with ConA was collected at 0, 1, 2, 4, 6, 8 and 10 weeks post-infection. Sandwich ELISA and RT-PCR were used to measure the expressions of IL-17A and IL-23p19 on protein and mRNA level. RESULTS: The dynamic changes of IL-17A and IL-23p19 showed a positive correlation. The level of IL-17A increased and reached the peak at 1 week after the infection, reduced at 4 weeks after the infection, and was even lower at 8 weeks post-infection. The level of IL-17 mRNA increased at 1 week post-infection, and then decreased gradually at 2 weeks post-infection. Being consistent with the dynamic expression of IL-17A, the IL-23p19 expression increased at 1 week post-infection, went up to the peak at 2 weeks post-infection, and gradually reduced into the normal level at 4 weeks. However, the expression of IL-23p19 mRNA fluctuated in the normal range, increased at 4 weeks post-infection, and reached the peak at 6 weeks post-infection. CONCLUSIONS: IL-17 and IL-23 are of co-expression in the mice after schistosome infection. There is a significant increase in the early stage of the infection. IL-17 and IL-23 may play important roles during the immune process in the very early stage of Schistosoma infection.