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Abstract Background The efficacy of human umbilical cord mesenchymal stem cell (hUC-MSC) transplantation in treating systemic lupus erythematosus (SLE) has been confirmed by small-scale clinical trials. However, these trials focused on severe or refractory SLE, while few studies focused on mild SLE. Therefore, this study focused on the therapeutic effects of hUC-MSC transplantation in early-stage or mild MRL/lpr lupus model mice. Methods Commercially available hUC-MSCs were transplanted into 8-week-old MRL/lpr mice by tail vein injection. Flow cytometry was used to analyze B cells and their subsets in the peripheral blood. Further, plasma inflammatory factors, autoantibodies, and plasma biochemical indices were detected using protein chip technology and ELISA kits. In addition, pathological staining and immunofluorescence were performed to detect kidney injury in mice. Results hUC-MSC transplantation did not affect the mice’s body weight, and both middle and high dose hUC-MSC transplantation (MD and HD group) actually reduced spleen weight. hUC-MSC transplantation significantly decreased the proportion of plasmablasts (PB), IgG1− PB, IgG1+ PB, IgG1+ memory B (MB) cells, IgG1+ DN MB, and IgG1+ SP MB cells. The hUC-MSC transplantation had significantly reduced plasma levels of inflammatory factors, such as TNF-α, IFN-γ, IL-6, and IL-13. Pathological staining showed that the infiltration of glomerular inflammatory cells was significantly reduced and that the level of glomerular fibrosis was significantly alleviated in hUC-MSC-transplanted mice. Immunofluorescence assays showed that the deposition of IgG and IgM antibodies in the kidneys of hUC-MSC-transplanted mice was significantly lower than in the control. Conclusion hUC-MSC transplantation could inhibit the proliferation and differentiation of peripheral blood B cells in the early-stage of MRL/lpr mice, thereby alleviating the plasma inflammatory environment in mice, leading to kidney injury remission. The study provides a new and feasible strategy for SLE treatment.

Animal models play an indispensable role in the study of human diseases. However, animal models of different diseases do not fully mimic the complex internal environment of humans. Immunodeficient mice are deficient in certain genes and do not express these or show reduced expression in some of their cells, facilitating the establishment of humanized mice and simulation of the human environment in vivo. Here, we summarize the developments in immunodeficient mice, from the initial nude mice lacking T lymphocytes to NOD/SCID rgnull mice lacking T, B, and NK cell populations. We describe existing humanized immune system mouse models based on immunodeficient mice in which human cells or tissues have been transplanted to establish a human immune system, including humanized-peripheral blood mononuclear cells (Hu-PBMCs), humanized hematopoietic stem cells (Hu-HSCs), and humanized bone marrow, liver, thymus (Hu-BLT) mouse models. The different methods for their development involve varying levels of complexity and humanization. Humanized mice are widely used in the study of various diseases to provide a transitional stage for clinical research. However, several challenges persist, including improving the efficiency of reconstructing the human B cell immune response, extending lifespan, improving the survival rate of mice to extend the observation period, and improving the development of standardized commercialized models and as well as their use. Overall, there are many opportunities and challenges in the development of humanized immune system mouse models which can provide novel strategies for understanding the mechanisms and treatments of human disease.

Animal models have played a crucial role in the understanding of the mechanisms and treatments of human diseases; however, owing to the large differences in genetic background and disease-specific characteristics, animal models cannot fully simulate the occurrence and progression of human diseases. Recently, humanized immune system mice, based on immunodeficient mice, have been developed that allow for the partial reconstruction of the human immune system and mimic the human in vivo microenvironment. Systemic lupus erythematosus (SLE) is a complex disease characterized by the loss of tolerance to autoantigens, overproduction of autoantibodies, and inflammation in multiple organ systems. The detailed immunological events that trigger the onset of clinical manifestations in patients with SLE are still not well known. Two methods have been adopted for the development of humanized SLE mice. They include transferring peripheral blood mononuclear cells from patients with SLE to immunodeficient mice or transferring human hematopoietic stem cells to immunodeficient mice followed by intraperitoneal injection with pristane to induce lupus. However, there are still several challenges to be overcome, such as how to improve the efficiency of reconstruction of the human B cell immune response, how to extend the lifespan and improve the survival rate of mice to extend the observation period, and how to improve the development of standardized commercialized models and use them. In summary, there are opportunities and challenges for the development of humanized mouse models of SLE, which will provide novel strategies for understanding the mechanisms and treatments of SLE.

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that was traditionally thought to be closely related to genetic and environmental risk factors. Although treatment options for SLE with hormones, immunosuppressants, and biologic drugs are now available, the rates of clinical response and functional remission of these drugs are still not satisfactory. Currently, emerging evidence suggests that gut microbiota dysbiosis may play crucial roles in the occurrence and development of SLE, and manipulation of targeting the gut microbiota holds great promises for the successful treatment of SLE. The possible mechanisms of gut microbiota dysbiosis in SLE have not yet been well identified to date, although they may include molecular mimicry, impaired intestinal barrier function and leaky gut, bacterial biofilms, intestinal specific pathogen infection, gender bias, intestinal epithelial cells autophagy, and extracellular vesicles and microRNAs. Potential therapies for modulating gut microbiota in SLE include oral antibiotic therapy, fecal microbiota transplantation, glucocorticoid therapy, regulation of intestinal epithelial cells autophagy, extracellular vesicle-derived miRNA therapy, mesenchymal stem cell therapy, and vaccination. This review summarizes novel insights into the mechanisms of microbiota dysbiosis in SLE and promising therapeutic strategies, which may help improve our understanding of the pathogenesis of SLE and provide novel therapies for SLE.

Nowadays, with the improvements in living standards and changes in living habits, high-fat diet (HFD) has become much more common in the populations worldwide. Recent studies have shown that HFD could induce lipid accumulation, and structural and functional abnormalities, accompanied by the release of large amounts of pro-inflammatory cytokines, in proximal tubular epithelial cells (PTECs). These findings indicate that, as an emerging risk factor, PTEC injury-induced by HFD may be closely related to inflammation; however, the potential mechanisms underlying this phenomenon is still not well-known, but may involve the several inflammatory pathways, including oxidative stress-related signaling pathways, mitochondrial dysfunction, the myeloid differentiation factor 2/Toll like receptor 4 (MD2/TLR4) signaling pathway, the ERK1/2-kidney injury molecule 1 (KIM-1)-related pathway, and nuclear factor-κB (NF-κB) activation, etc., and the detailed molecular mechanisms underlying these pathways still need further investigated in the future. Based on lipid abnormalities-induced inflammation is closely related to the development and progression of chronic kidney disease (CKD), to summarize the potential mechanisms underlying HFD-induced renal proximal tubular inflammatory injury, may provide novel approaches for CKD treatment.

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease. Although previous studies have demonstrated that SLE is related to the imbalance of cells in the immune system, including B cells, T cells, and dendritic cells, etc., the mechanisms underlying SLE pathogenesis remain unclear. Therefore, effective and low side-effect therapies for SLE are lacking. Recently, mesenchymal stem cell (MSC) therapy for autoimmune diseases, particularly SLE, has gained increasing attention. This therapy can improve the signs and symptoms of refractory SLE by promoting the proliferation of Th2 and Treg cells and inhibiting the activity of Th1, Th17, and B cells, etc. However, MSC therapy is also reported ineffective in some patients with SLE, which may be related to MSC- or patient-derived factors. Therefore, the therapeutic effects of MSCs should be further confirmed. This review summarizes the status of MSC therapy in refractory SLE treatment and potential reasons for the ineffectiveness of MSC therapy from three perspectives. We propose various MSC modification methods that may be beneficial in enhancing the immunosuppression of MSCs in SLE. However, their safety and protective effects in patients with SLE still need to be confirmed by further experimental and clinical evidence.