Unbalanced expression of membrane-bound and soluble programmed cell death 1 and programmed cell death ligand 1 in systemic juvenile idiopathic arthritis

Polyarticular juvenile idiopathic arthritis has a distinct co-inhibitor receptor profile

OBJECTIVES

JIA is the most common rheumatic disease of childhood; the pathogenesis is associated with T-cell activation. T-cell activation can be counterbalanced by signals generated by inhibitory receptors (IRs) such as CTLA-4, PD-1, LAG-3 and TIM-3. Here, we identify the role of IRs in the pathogenesis of different JIA subtypes.

METHODS

In total, we included 67 oligoarticular JIA, 12 IgM-RF negative polyarticular JIA, 17 enthesitis-related arthritis, 11 systemic JIA patients and 10 healthy controls. We collected plasma (and SF) samples from the patients either at the onset or during a flare of their disease. We measured the soluble levels of co-IRs (IL-2Rα, 4-1BB, CD86, TGF-β1, CTLA-4, PD-L1, PD-1, TIM-3, LAG- 3, Galectin-9) by cytometric bead array kits and their cellular expression (PD-1, CTLA-4, TIM-3, LAG-3) by flow cytometry. We compared the plasma levels and cellular expressions of different co-IRs within different JIA subgroups.

RESULTS

The polyarticular JIA group was different from the three other examined JIA subgroups, having higher levels of plasma sCTLA-4 (P < 0.001), sPD-1 (P < 0.05) and s4-1BB (P < 0.05) when compared with the other JIA subgroups and healthy controls. We analysed the cellular surface expression of different co-IRs on the peripheral blood mononuclear cells of different JIA subtypes. Similar to plasma levels, both the percentage (P < 0.05) and the mean fluorescence intensity (P < 0.01) of CTLA4 expression were higher in the polyarticular JIA subgroup.

CONCLUSION

This is the first report studying the expression profile of different co-IRs in different subtypes of JIA. Polyarticular JIA patients had a different co-IR profile, having more CTLA-4, PD-1 and 4-1BB in their plasma than the other subtypes of JIA.

Effects of high-fat diet on thyroid autoimmunity in the female rat

BACKGROUND

While contributions of dyslipidemia to autoimmune diseases have been described, its impact on thyroid autoimmunity (TA) is less clear. Programmed cell death 1(PD-1)/PD-ligand 1 (PD-L1) immune checkpoint is crucial in preventing autoimmune attack while its blockade exacerbates TA. We thus unveiled the effect of high-fat diet (HFD) on TA, focusing on the contribution of PD-1/PD-L1.

METHODS

Female Sprague Dawley (SD) rats were randomly fed with a regular diet or HFD (60% calories from fat) for 24 weeks. Then, thyroid ultrasonography was performed and samples were collected for lipid and thyroid-related parameter measure.

RESULTS

HFD rats exhibited hyperlipemia and abnormal biosynthesis of the unsaturated fatty acid in serum detected by lipidomics. These rats displayed a relatively lower echogenicity and increased inflammatory infiltration in thyroid accompanied by rising serum thyroid autoantibody levels and hypothyroidism, mimicking human Hashimoto's thyroiditis. These alterations were concurrent with decreased mRNA and immunostaining of intrathyroidal PD-1 and also serum PD-1 levels but not the PD-L1 expression, suggesting a role of a PD-1 pathway. Meanwhile, the infiltration of B and T cell, a key cellular event inhibited by the PD-1 signals, was enhanced in the thyroid of HFD rats, along with thyroid fibrosis and apoptosis.

CONCLUSIONS

Our data suggest that HFD triggers TA through a mechanism possibly involving downregulation of PD-1-related immunosuppression, providing a novel insight into the link between dyslipidemia and autoimmune toxicities.