Human umbilical cord mesenchymal stem cells improve disease characterization of Sjogren's syndrome in NOD mice through regulation of gut microbiota and Treg/Th17 cellular immunity.

Background: For the unclear pathogenesis of Sjogren's syndrome (SS), further exploration is necessary. Mesenchymal stem cells (MSCs) and derived exosomes (MSCs‐exo) have exhibited promising results in treating SS. Object: This study aimed to investigate the effect and mechanism of human umbilical cord MSCs (UC‐MSCs) on SS. Methods: Nonobese Diabetic (NOD) mouse splenic T cells were co‐cultured with UC‐MSCs and UC‐MSCs‐exo, and interferon‐gamma (IFN‐γ), interleukin (IL)‐6, IL‐10, prostaglandin E2 (PGE2), and transforming growth factor‐β1 (TGF‐β1) levels in the supernatant were assessed by quantitative real‐time polymerase chain reaction and enzyme‐linked immunosorbent assay. Co‐cultured T cells were injected into NOD mice via the tail vein. The inflammatory cell infiltration in the intestine and the submandibular gland was characterized by hematoxylin‐eosin staining. Treg/Th17 homeostasis within the spleen was determined by flow cytometry. Gut microbiota was detected by 16S rRNA sequencing, and the relationship between differential microbiota and Treg/Th17 cytokines was analyzed by the Pearson correlation coefficient. Results: UC‐MSCs, UC‐MSCs‐exo, and NOD mouse splenic T cells were successfully cultured and identified. After T cells were co‐cultured with UC‐MSCs and UC‐MSCs‐exo, both IFN‐γ and IL‐6 were decreased while IL‐10, PGE2, and TGF‐β1 were increased in transcriptional and translational levels. UC‐MSCs and UC‐MSCs‐exo partially restored salivary secretion function, reduced Ro/SSA antibody and α‐Fodrin immunoglobulin A levels, reduced inflammatory cell infiltration in the intestine and submandibular gland, raised proportion of Treg cells, decreased IFN‐γ, IL‐6, IL‐2, IL‐17, lipopolysaccharide, and tumor necrosis factor‐alpha levels, and raised IL‐10, Foxp3, and TGF‐β1 levels by affecting co‐cultured T cells. The intervention of UC‐MSCs and UC‐MSCs‐exo improved intestinal homeostasis in NOD mice by increasing microbiota diversity and richness. Additionally, differential microbiota was significantly associated with Treg/Th17 cytokine levels. Conclusion: Human UC‐MSCs and UC‐MSCs‐exo improved disease characterization of SS in NOD mice through regulation of gut microbiota and Treg/Th17 cellular immunity. [ABSTRACT FROM AUTHOR]