Transcriptional analysis of co-stimulatory molecules in ankylosing spondylitis

Abstract

Ankylosing spondylitis (AS) is a chronic inflammatory autoimmune disease where T-cell dysregulation plays a pivotal role. A balance of co-stimulatory and co-inhibitory molecules governs the activation of T cells. This study aimed to investigate the mRNA expression profiles of these immune checkpoint signals in AS patients. A cohort of 33 AS patients and 28 healthy controls (HC) from the Taiwanese population was recruited. The mRNA expression levels of five co-stimulatory molecules (CD28, CD40, CD40L, OX40, and OX40L) and one co-inhibitory molecule (TIM-3) were quantified using qRT-PCR. Relative expression was calculated via the 2 −△△ct method, normalized to beta-actin. Significant downregulation of several immune checkpoint molecules was observed in AS patients. Compared with HCs, AS patients exhibited a 2.67-fold reduction in CD28 ( p < 0.0001), a 2.37-fold reduction in CD40L ( p < 0.0001), a 2.20-fold reduction in TIM-3 ( p < 0.0001), and a 1.47-fold reduction in CD40 ( p = 0.006). No significant differences were found in the expression of OX40 and OX40L between the two groups. The concurrent downregulation of both activating and inhibitory signals suggests a trend toward coordinated downregulation of the immune checkpoint network in the peripheral blood of AS patients. This phenomenon may represent chronic immune exhaustion or the redistribution of activated immune cells to sites of inflammation. These molecules, particularly CD40L and TIM-3, may represent candidates for further biomarkers that warrant further investigation in large, age- and sex-matched cohorts.