Modeling chondrocyte/synoviocyte inflammation: a comparative approach to recombinant interleukin-10 treatment strategies and their functional differences.

Abstract

OBJECTIVE: To investigate the impact of recombinant equine IL‑10 (rIL-10) on inflammatory and catabolic responses in stimulated equine chondrocytes and synoviocytes under different treatment timings. METHODS: Primary chondrocytes and synoviocytes were stimulated with IL‑1β and tumor necrosis factor-α (TNF‑α) and treated with rIL‑10 (10, 20, and 50 ng/mL) under 3 timing models, added 1 hour before stimulation (model 1), 1 hour after stimulation (model 2), or simultaneously with cytokines (model 3). Cultures were maintained for 48 hours. Gene expression was assessed by quantitative real-time PCR, cytokine secretion by multiplex assay, and prostaglandin-E2 by ELISA. RESULTS: rIL‑10 modulated inflammation and catabolic gene expression in a concentration‑ and timing‑dependent manner. In chondrocytes, treatment with 20 ng/mL rIL‑10 reduced IL‑1β, IL‑8, and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) expression, though 10 ng/mL was more effective in model 2. Treatment with 50 ng/mL rIL-10 increased IL‑6, and 20 ng/mL increased matrix metalloproteinase (MMP)-13. In synoviocytes, rIL‑10 broadly suppressed IL‑1β, IL‑8, MMP-13, and ADAMTS transcripts, though IL‑6 was variably upregulated. At the protein level, rIL‑10 decreased TNF‑α, IL‑6, and IL‑8 secretion in chondrocytes but paradoxically increased IL‑1β under some conditions. In synoviocytes, cytokine secretion changes were less consistent, with modest TNF‑α reduction. rIL‑10 increased prostaglandin-E2 production in both cell types across all models. CONCLUSIONS: rIL‑10 modulates equine joint cell inflammation in a concentration‑, cell type‑, and timing‑dependent manner, emphasizing the importance of treatment design in preclinical testing. CLINICAL RELEVANCE: These data support optimizing IL‑10-based biologics and highlight considerations for in vitro screening of anti‑inflammatory treatments for equine osteoarthritis.