MANF inhibits Sjögren's syndrome salivary gland epithelial cell apoptosis and antigen expression of Ro52/SSA through endoplasmic reticulum stress/autophagy pathway.

BACKGROUND: Sjögren's syndrome (SS) is a typical autoimmune disease characterized by lymphocyte infiltration accompanied by the production of Ro52/SSA and La/SSB autoantibodies against whole body ribonucleoprotein particles. The release of type I IFN can induce endoplasmic reticulum stress (ERS) in submandibular gland cells. ERS not only produces a large number of Ro52/SSA antigens and changes their location, but also down-regulates autophagy and increases apoptosis. METHOD: We collected human submandibular gland tissue samples, established an Experimental Sjögren's syndrome (ESS) mouse model, and used submandibular gland cells to test whether Mesencephalic astrocyte-derived neurotrophic factor (MANF) could reverse ERS-induced autophagy downregulation and reduce apoptosis and Ro52/SSA antigen expression. RESULT: It was found that MANF could reduce lymphocyte infiltration and the proportion of CD4+ T cell subsets in the salivary glands, reduce the phosphorylation of AKT and mTOR proteins and the expression of ERS-related proteins, and increase the expression of autophagy proteins. We also found that MANF can reduce the expression of Ro52/SSA antigen on the cell membrane and reduce apoptosis. CONCLUSION: In short, we found that MANF can activate autophagy, inhibit apoptosis and reduce the expression of Ro52/SSA by regulating the AKT/mTOR/LC3B signaling pathway. The above results suggest that MANF may be a protective factor against SS.

CXCL9, 10, 11/CXCR3 Axis Contributes to the Progress of Primary Sjogren's Syndrome by Activating GRK2 to Promote T Lymphocyte Migration.

Primary Sjogren's syndrome (pSS) is a systemic autoimmune disease that causes dysfunction of secretory glands and the specific pathogenesis is still unknown. The CXCL9, 10, 11/CXCR3 axis and G protein-coupled receptor kinase 2 (GRK2) involved in many inflammation and immunity processes. We used NOD/Ltj mice, a spontaneous SS animal model, to elucidate the pathological mechanism of CXCL9, 10, 11/CXCR3 axis promoting T lymphocyte migration by activating GRK2 in pSS. We found that CD4 + GRK2, Th17 + CXCR3 was apparently increased and Treg + CXCR3 was significantly decreased in the spleen of 4W NOD mice without sicca symptom compared to ICR mice (control group). The protein levels of IFN-γ, CXCL9, 10, 11 increased in submandibular gland (SG) tissue accompanied by obvious lymphocytic infiltration and Th17 cells overwhelmingly infiltrated relative to Treg cells at the sicca symptom occurs, and we found that the proportion of Th17 cells was increased, whereas that of Treg cells was decreased in spleen. In vitro, we used IFN-γ to stimulate human salivary gland epithelial cells (HSGECs) co-cultured with Jurkat cells, and the results showed that CXCL9, 10, 11 was increased by IFN-γ activating JAK2/STAT1 signal pathway and Jurkat cell migration increased with the raised of cell membrane GRK2 expression. HSGECs with tofacitinib or Jurkat cells with GRK2 siRNA can reduce the migration of Jurkat cells. The results indicate that CXCL9, 10, 11 significantly increased in SG tissue through IFN-γ stimulating HSGECs, and the CXCL9, 10, 11/CXCR3 axis contributes to the progress of pSS by activating GRK2 to promote T lymphocyte migration.