Curcumin-mediated Modulation of T-bet and CD8+ T Cells: A Potential Anti-inflammatory Mechanism in Knee Osteoarthritis

Abstract

Osteoarthritis (OA) is the most common form of arthritis, characterized by pathological changes in joint components. Increasing evidence suggests that helper T (T_H) lymphocytes play a pivotal role in the inflammatory processes associated with OA. Curcumin, the primary polyphenolic compound found in Curcuma longa, exhibits potent antioxidant and anti-inflammatory properties. This study aimed to evaluate the effects of curcumin on the gene expression of key transcription factors of T_H1 and T_H2 cells and to explore their associations with clinical and immunological parameters in patients with knee OA.

This mechanistic sub-study presents a secondary molecular analysis of RNA biospecimens from a previously completed double-blind, placebo-controlled clinical trial involving 30 patients with knee OA. Participants were randomly assigned to receive either 80 mg/day of nano-micelle curcumin or a placebo for 3 months. Expression levels of T-box transcription factor 21 (T-bet) and GATA binding protein 3 (GATA3), the key transcription factors of T_H1 and T_H2 cells, respectively, were quantified using SYBR Green-based real-time PCR. Their associations with changes in visual analogue scale (VAS) score, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and percentages of CD4⁺ and CD8⁺ T cells were analyzed.

Curcumin administration significantly reduced T-bet gene expression compared to baseline and showed a positive correlation with the frequency of CD8⁺ T cells, while GATA3 expression remained unchanged.

These findings may provide a novel molecular perspective on curcumin's potential to influence CD8⁺ T cell dynamics by modulating T_H1-associated transcriptional programs.