Mesenchymal stem cells (MSCs) play an anti-inflammatory role by secreting certain bioactive molecules to exert their therapeutic effects for disease treatment. However, the underlying mechanism of MSCs in chronic autoimmune liver diseases—primary biliary cholangitis (PBC), for example—remains to be elucidated. Human umbilical cord–derived MSCs (UC-MSCs) were injected intravenously into 2-octynoic acid coupled to bovine serum albumin (2OA-BSA)-induced autoimmune cholangitis mice. Serum levels of biomarkers and autoantibodies, histologic changes in the liver, diverse CD4+ T-cell subsets in different tissues, and chemokine activities were analyzed. Moreover, we investigated galectin-9 (Gal-9) expression and its function in UC-MSCs. In this study, UC-MSC transplantation (UC-MSCT) significantly ameliorated liver inflammation, primarily by diminishing T helper 1 (Th1) and Th17 responses as well as modifying liver chemokine activities in experimental autoimmune cholangitis mice. Mechanistically, UC-MSCs significantly repressed the proliferation of CD4+ T cells and suppressed the differentiation of Th1 and Th17 cells, which was likely dependent on Gal-9. Furthermore, the signal transducer and activator of transcription (STAT) and c-Jun N-terminal kinase (JNK) signaling pathways were involved in the production of Gal-9 in UC-MSCs. These results suggest that Gal-9 contributes significantly to UC-MSC–mediated therapeutic effects and improve our understanding of the immunomodulatory mechanisms of MSCs in the treatment of PBC.

Objective To investigate the role of curcumin in the treatment of lupus nephritis (LN) by inhibiting the migration of neutrophils and the underlying mechanism involved. Methods Two lupus mouse models, MRL/lpr mice and R848-treated mice, were treated with 50 mg/kg curcumin by intraperitoneal injection. H&E and Masson staining were used to estimate histopathological changes in the kidney. Immunofluorescence was used to assess the deposition of immune complexes. The expression of inflammatory factors was detected by enzyme-linked immunosorbent assay (ELISA) and real-time reverse transcription polymerase reaction (RT-PCR), and the protein expression was detected by western blotting. Results We revealed the remarkable potential of curcumin in improving inflammatory conditions in both MRL/lpr mice and R848-induced lupus mice. Curcumin effectively decelerates the progression of inflammation and diminishes the infiltration of neutrophils and their release of pivotal inflammatory factors, thereby reducing inflammation in renal tissues. Mechanistically, curcumin significantly inhibits the expression of p-PI3K, p-AKT and p-NF-κB, which are upregulated by interleukin-8 to induce neutrophil migration and renal inflammation, thereby reducing neutrophil migration and the release of inflammatory factors. Conclusion Curcumin significantly inhibits the recruitment of neutrophils and the release of proinflammatory factors in the kidney by inhibiting the PI3K/AKT/NF-κB signalling pathway, providing new therapeutic targets and medication strategies for the treatment of LN.

Mixed human umbilical cord‐derived mesenchymal stem cells (UC‐MSCs) are widely applied in clinical trials to treat various diseases due to their multipotent differentiation potential and immune regulatory activities. However, the lack of a clear understanding of their heterogeneity hampers their application to precisely treat diseases. Moreover, few studies have experimentally authenticated the functions of so‐called UC‐MSC subpopulations classified from scRNA‐seq samples. Here, this work draws a large‐scale single‐cell transcriptomic atlas and identified three clusters (C1, C2, and C3), representing the primed, intermediate, and stem statuses individually. The C1 and C3 clusters feature higher expression of cytokines and stemness markers, respectively. Surprisingly, further experimental assays reveal that the BAMBI^highMFGE8^high C1 subgroup has a unique phenotype, distinct transcriptomic profile, and limited adipogenic differentiation potential but compromised immunosuppressive activity in vitro and in vivo in lupus mice. Thus, this work is helpful to clarify the nature of human UC‐MSCs and to choose optimal MSC types to treat specific diseases in the future.

In search for new targets for the diagnosis and treatment of lupus nephritis (LN), we employed TMT-liquid chromatography-triple quadrupole mass spectrometry (TMT-LC–MS/MS) combined with RNA-seq and identified a panel of proteins that was dysregulated both at protein level and mRNA level in active LN patients compared with healthy controls. We chose to study the role of IGFBP2 since it is a relatively understudied protein in the context of LN. We further validated that IGFBP2 significantly increased and correlated with SLE activity index in active LN patients. The receiver operator characteristic (ROC) curve suggested that plasma IGFBP2 had a high diagnostic efficiency for distinguishing between inactive and active LN patients (AUC = 0.992; 95% CI = 0.974–1.000; P < 0.001). We demonstrated neutralizing IGFBP2-downregulated CD4⁺ T cell activation, upregulated the ratio of Treg, downregulated AKT/mTOR/4E-BP1 pathway, and significantly improved nephritis in MRL/lpr mice. In all, our work demonstrated IGFBP2 as a biomarker specific for active LN and blocking IGFBP2 could be a new target for treating LN. Key messages: Plasma IGFBP2 is a promising diagnostic marker for distinguishing stable LN from active LN, and it is also a predictor for the poor prognosis of LN. Blockade of IGFBP2 can significantly improve the pathological damage of LN. IGFBP2 may regulate activation of CD4⁺ T and Treg ratio. Neutralizing IGFBP2 downregulates AKT/mTOR/4E-BP1 pathway.

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by the production of autoantibodies and tissue inflammation. Mesenchymal stem cells (MSCs) have emerged as a promising candidate therapy for SLE owing to the immunomodulatory and regenerative properties. Circulating miRNAs are small, single-stranded noncoding RNAs in a variety of body fluids that regulate numerous immunologic and inflammatory pathways. Recent studies have revealed many differentially expressed circulating miRNAs in autoimmune diseases including SLE. However, the role of circulating miRNAs in SLE has not been extensively studied. Here, we performed small RNA sequencing analysis to compare the circulating miRNA profiles of SLE patients before and after MSC transplantation (MSCT), and identified a significant decrease of circulating miR-320b level during MSCT. Importantly, we found that the expression of circulating miR-320b and its target gene MAP3K1 was closely associated with SLE disease activity. The in vitro experiments showed that decreased MAP3K1 level in SLE peripheral blood mononuclear cells (PBMCs) was involved in CD4 T-cell proliferation. In MRL/lpr mice, miR-320b overexpression aggravated symptoms of SLE, while miR-320b inhibition could promote disease remission. Besides, MSCs regulate miR-320b/MAP3K1 expression both in vitro and in vivo. Our results suggested that circulating miR-320b and MAP3K1 may be involved in CD4 T-cell proliferation in SLE. This trial is registered with NCT01741857.

Umbilical cord‐derived mesenchymal stromal cells (MSCs) transplantation is a promising therapy for systemic sclerosis (SSc) because of their distinctive antifibrotic and immunomodulatory properties. To enhance the effects of MSCs transplantation, novel engineered MSC aggregates preconditioned with human E/N‐cadherin fusion protein (hE/N‐cad‐Fc) and interleukin‐6 (IL‐6) for SSc treatment are fabricated and named 3D‐Cad/IL6‐MSCs. These novel‐engineered MSC aggregates possess tighter cellular cohesion and exhibit enhanced antiapoptotic, immunosuppressive, and proangiogenic capabilities according to transcriptomic analyses. Moreover, 3D‐Cad/IL6‐MSCs have improved immunoregulatory effects on peripheral blood mononuclear cells (PBMCs), CD4⁺ T cells, and CD8⁺ T cells in vitro because of the synergistic preconditioning from IL‐6 and bioactive hE/N‐cad‐Fc. Upon intravenous injection, 3D‐Cad/IL6‐MSCs significantly mitigate skin and lung fibrosis and prolong the retention duration in bleomycin (BLM)‐induced SSc mouse model. In detail, they suppress excessive infiltration of macrophages and T cells in the injured skin and lungs and reestablish the immune equilibrium of circulating CD4⁺ T‐cell subsets in vivo. These results suggest that 3D‐Cad/IL6‐MSCs are ideal candidates for SSc therapy and optimize the clinical utilization of MSCs.