Systemic lupus erythematosus (SLE) is a chronic autoimmune disease whose onset and progression are affected by genetic and environmental factors. The purpose of this study is to identify the influence of gut microbiota in the pathogenesis of SLE, and to investigate the mechanism involved. Fecal microbiota from C57/BL6 mice and SLE prone mice were examined using next-generation sequencing (NGS). Germ free mice were given fecal microbiota transplantation (FMT), and their gut microbiome and gene expression in recipients’ colons were examined by NGS. The anti-double stranded DNA (anti-dsDNA) antibodies in recipients were determined using an enzyme-linked immunosorbent assay (ELISA). The immune cell profiles of mice were analyzed by flow cytometry at the 3rd week after FMT, and the expression of genes associated with SLE after FMT was determined using quantitative real-time PCR (qRT-PCR). The fecal microbiota of SLE mice had lower community richness and diversity than healthy mice. Fecal microbiota of recipient mice were similar to their donors. Fecal microbiome from SLE mice could lead to a significant increase of anti-dsDNA antibodies and promote the immune response in recipient mice. Our results also indicated that fecal microbiome from SLE mice resulted in significant changes in the distribution of immune cells and upregulated expression of certain lupus susceptibility genes. SLE is associated with alterations of gut microbiota. Fecal microbiome from SLE mice can induce the production of anti-dsDNA antibodies in germ free mice and stimulate the inflammatory response, and alter the expression of SLE susceptibility genes in these mice.

Background: The gut microbiota was shown to play a crucial role in the development of vascular dysfunction, and the bacterial composition differed between healthy controls and coronary artery disease patients. The goal of this study was to investigate how the gut microbiota affects host metabolic homeostasis at the organism scale. Methods: We colonized germ-free C57BL/6 J mice with faeces from healthy control donors (Con) and coronary artery disease (CAD) patients and fed both groups a high fat diet for 12 weeks. We monitored cholesterol and vascular function in the transplanted mice. We analysed bile acids profiles and gut microbiota composition. Transcriptome sequencing and flow cytometry were performed to evaluate inflammatory and immune response. Results: CAD mice showed increased reactive oxygen species generation and intensive arterial stiffness. Microbiota profiles in recipient mice clustered according to the microbiota structure of the human donors. Clostridium symbiosum and Eggerthella colonization from CAD patients modulated the secondary bile acids pool, leading to an increase in lithocholic acid and keto-derivatives. Subsequently, bile acids imbalance in the CAD mice inhibited hepatic bile acids synthesis and resulted in elevated circulatory cholesterol. Moreover, the faecal microbiota from the CAD patients caused a significant induction of abnormal immune responses at both the transcriptome level and through the enhanced secretion of cytokines. In addition, microbes belonging to CAD promoted intestinal inflammation by contributing to lamina propria Th17/Treg imbalance and worsened gut barrier permeability. Conclusions: In summary, our findings elucidated that the gut microbiota impacts cholesterol homeostasis by modulating bile acids. In addition, the CAD-associated bacterial community was shown to function as an important regulator of systemic inflammation and to influence arterial stiffness.

Background: Patients with rheumatoid arthritis (RA) have an increased risk for cardiovascular disease. We examined the effect of gut microbiota in a mouse model of RA that develops atherosclerosis.Methods: We created three groups of K/BxN female mice that were positive for the anti‐glucose‐6‐phosphate isomerase (GPI) antibody: control diet (CD), high fat diet (HFD), and HFD with hydroxychloroquine (HFD + HCQ). Serological tests were used to detect the serum levels of total cholesterol (TCHO), low‐density lipoprotein cholesterol (LDL‐C), triglyceride (TG), high‐density lipoprotein cholesterol (HDL‐C), anti‐GPI antibody titers, and serum cytokines. Atherosclerotic plaque was determined by histological analysis, and gut microbiota were determined by 16sV4 sequencing.Results: Relative to mice given the CD, those receiving the HFD had increased serum levels of LDL‐C, TCHO, and TG, decreased serum levels of HDL‐C, increased atherosclerotic lesions in the aortic root, and altered gut microbiota. Addition of HCQ to HFD decreased the serum levels of LDL‐C, TCHO, and TG, increased serum levels of HDL‐C, and decreased the atherosclerotic lesions in the aortic root. Mice receiving HFD + HCQ also had the greatest bacterial diversity among the three experimental groups. Moreover, HCQ treatment significantly increased the abundance of Akkermansia and Parabacteroides, and decreased the abundance of Clostridium sensu stricto cluster 1, and therefore may be responsible for the reduced RA‐associated atherosclerosis and dyslipidemia.Conclusion: Our mouse model of RA indicated that HFD increased ankle width and aggravated atherosclerosis and dyslipidemia, and that HCQ alleviated the dyslipidemia and atherosclerosis, but had no effect on ankle width.

Oxymatrine, also known as ammothamnine or oxysophoridine, is a natural compound isolated from Sophora flavescens (in Chinese, Kushen), and many previous researchers have characterized its anti-inflammatory, anti-fibrotic and anti-tumor properties. However, the underlying anti-tumor immunological mechanism of oxymatrine remains elusive. In this study, we carried out experiments both in vitro and in vivo and investigated the anti-tumor effect of oxymatrine to inhibit the proliferation and migration of melanoma B16 cells, while promoting apoptosis. Oxymatrine upregulated CD4⁺ T, CD8⁺ T and NKT cells, downregulated Treg cells, promoted TNF-α secretion, and successfully modulated the immune microenvironment and ultimately suppressed melanoma development in subcutaneous tumor models established in mice. Evidence from network pharmacology and RNAseq suggested that possible targets of oxymatrine for melanoma treatment included PD-L1 and MYC. We observed oxymatrine inhibited PD-L1 and MYC expression in melanoma cells via qRT-PCR and western blotting analysis, and found MYC potentially regulated PD-L1 to mediate anti-tumor effects. These findings provide insight into the mechanism by which oxymatrine inhibits melanoma and enhances the anti-tumor immune effect. In summary, our study proposes a novel approach to suppress melanoma by targeting the MYC/PD-L1 pathway using oxymatrine, which may develop into a less toxic and more efficient anti-tumor agent for melanoma treatment.

Marginal zone (MZ) B cells contain a large number of autoreactive clones and the expansion of this compartment has been associated with autoimmunity. MZ B cells also efficiently transport blood-borne antigen to the follicles where they activate T cells and differentiate into plasma cells. Using the B6.NZM2410.Sle1.Sle2.Sle3 (B6.TC) model of lupus, we show that the IgM⁺ CD1d^hi/MZ B-cell compartment is expanded, and a large number of them reside inside the follicles. Contrary to the peripheral B-cell subset distribution and their activation status, the intrafollicular location of B6.TC IgM⁺ CD1d^hi/MZ B cells depends on both bone marrow- and stromal-derived factors. Among the factors responsible for this intrafollicular location, we have identified an increased response to CXCL13 by B6.TC MZ B cells and a decreased expression of VCAM-1 on stromal cells in the B6.TC MZ. However, the reduced number of MZ macrophages observed in B6.TC MZs was independent of the IgM⁺ CD1d^hi/B-cell location. B7-2 but not B7-1 deficiency restored IgM⁺ CD1d^hi/MZ B-cell follicular exclusion in B6.TC mice, and it correlated with tolerance to dsDNA and a significant reduction of autoimmune pathology. These results suggest that follicular exclusion of IgM⁺ CD1d^hi/MZ B cells is an important B-cell tolerance mechanism, and that B7-2 signaling is involved in breaching this tolerance checkpoint.