Increased levels of circulating soluble CD226 in multiple sclerosis.

BACKGROUND: The glycoprotein CD226 plays a key role in regulating immune cell function. Soluble CD226 (sCD226) is increased in sera of patients with several chronic inflammatory diseases but its levels in neuroinflammatory diseases such as multiple sclerosis (MS) are unknown. OBJECTIVE: To investigate the presence and functional implications of sCD226 in persons with multiple sclerosis (pwMS) and other neurological diseases. METHODS: The mechanisms of sCD226 production were first investigated by analyzing CD226 surface expression levels and supernatants of CD3/CD226-coactivated T cells. The role of sCD226 on dendritic cell maturation was evaluated. The concentration of sCD226 in the sera from healthy donors (HD), pwMS, neuromyelitis optica (NMO), and Alzheimer's disease (AD) was measured. RESULTS: CD3/CD226-costimulation induced CD226 shedding. Addition of sCD226 to dendritic cells during their maturation led to an increased production of the pro-inflammatory cytokine interleukin (IL)-23. We observed a significant increase in sCD226 in sera from pwMS and NMO compared to HD and AD. In MS, levels were increased in both relapsing-remitting multiple sclerosis (RRMS) and secondary-progressive multiple sclerosis (SPMS) compared to clinically isolated syndrome (CIS). CONCLUSION: Our data suggest that T-cell activation leads to release of sCD226 that could promote inflammation and raises the possibility of using sCD226 as a biomarker for neuroinflammation.

Vitamin D/CD46 Crosstalk in Human T Cells in Multiple Sclerosis.

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS), in which T-cell migration into the CNS is key for pathogenesis. Patients with MS exhibit impaired regulatory T cell populations, and both Foxp3+ Tregs and type I regulatory T cells (Tr1) are dysfunctional. MS is a multifactorial disease and vitamin D deficiency is associated with disease. Herein, we examined the impact of 1,25(OH)2D3 on CD4+ T cells coactivated by either CD28 to induce polyclonal activation or by the complement regulator CD46 to promote Tr1 differentiation. Addition of 1,25(OH)2D3 led to a differential expression of adhesion molecules on CD28- and CD46-costimulated T cells isolated from both healthy donors or from patients with MS. 1,25(OH)2D3 favored Tr1 motility though a Vitamin D-CD46 crosstalk highlighted by increased VDR expression as well as increased CYP24A1 and miR-9 in CD46-costimulated T cells. Furthermore, analysis of CD46 expression on T cells from a cohort of patients with MS supplemented by vitamin D showed a negative correlation with the levels of circulating vitamin D. Moreover, t-Distributed Stochastic Neighbor Embedding (t-SNE) analysis allowed the visualization and identification of clusters increased by vitamin D supplementation, but not by placebo, that exhibited similar adhesion phenotype to what was observed in vitro. Overall, our data show a crosstalk between vitamin D and CD46 that allows a preferential effect of Vitamin D on Tr1 cells, providing novel key insights into the role of an important modifiable environmental factor in MS.

A 3-week nonalcoholic steatohepatitis mouse model shows elafibranor benefits on hepatic inflammation and cell death.

The long duration of animal models represents a clear limitation to quickly evaluate the efficacy of drugs targeting nonalcoholic steatohepatitis (NASH). We, therefore, developed a rapid mouse model of liver inflammation (i.e., the mouse fed a high-fat/high-cholesterol diet, where cyclodextrin is co-administered to favor hepatic cholesterol loading, liver inflammation, and NASH within 3 weeks), and evaluated the effects of the dual peroxisome proliferator-activated receptor alpha/delta agonist elafibranor (ELA). C57BL6/J mice were fed a 60% high-fat, 1.25% cholesterol, and 0.5% cholic acid diet with 2% cyclodextrin in drinking water (HFCC/CDX diet) for 3 weeks. After 1 week of the diet, mice were treated orally with vehicle or ELA 20 mg/kg q.d. for 2 weeks. Compared with vehicle, ELA markedly reduced liver lipids and nonalcoholic fatty liver disease activity scoring, through steatosis, inflammation, and fibrosis (all P < 0.01 vs. vehicle). Flow cytometry analysis showed that ELA significantly improved the HFCC/CDX diet-induced liver inflammation by preventing the increase in total number of immune cells (CD45+), Kupffer cells, dendritic cells, and monocytes population, as well as the reduction in natural killer and natural killer T cells, and by blocking conversion of T cells in regulatory T cells. ELA did not alter pyroptosis (Gasdermin D), but significantly reduced necroptosis (cleaved RIP3) and apoptosis (cleaved caspase 3) in the liver. In conclusion, ELA showed strong benefits on NASH, including improvement in hepatic inflammation, necroptosis, and apoptosis in the 3-week NASH mouse. This preclinical model will be useful to rapidly detect the effects of novel drugs targeting NASH.