Serum MMP3 Correlated With IL1β Messenger RNA Expressions of Peripheral Blood Mononuclear Cells in Patients With Relapsing Polychondritis With Respiratory Involvement

OBJECTIVE: Respiratory involvement was intimately associated with poorer prognosis in patients with relapsing polychondritis (RP). We previously reported that high serum matrix metalloproteinase‐3 (MMP3) was frequently observed in patients with RP with respiratory involvement. Elevated MMP3 secreted through local inflammation may be associated with the development of airway lesions. METHODS: We collected peripheral blood mononuclear cells (PBMCs) and sera from 30 patients with RP and 14 healthy individuals. Interleukin (IL) 1β, IL6, and tumor necrosis factor (TNF) α messenger RNA (mRNA) expressions were analyzed in freshly isolated and cultured PBMCs with phytohemagglutinin and phorbol myristate acetate stimulation by real‐time reverse transcription polymerase chain reaction and serum MMP3 by enzyme‐linked immunosorbent assay (ELISA). RESULTS: We confirmed our previous finding that patients with respiratory involvements showed higher serum MMP3 compared with patients lacking respiratory involvement. IL1β mRNA expression was significantly higher in patients with RP than in healthy individuals after mitogenic stimulation. TNFα mRNA expression after stimulation was significantly lower in patients with RP compared with in healthy individuals. We performed correlation analyses between MMP3 and cytokine mRNA expressions in patients with RP. In patients with respiratory involvement, MMP3 correlated with IL1β and IL6 after stimulation. In patients without respiratory involvement, no positive correlations between MMP3 and cytokine mRNA expressions were observed regardless of culture condition. We did not find any positive correlations between MMP3 and TNFα mRNA expression in patients with RP. CONCLUSION: It is possible that IL1β mRNA expression associates by some means with airway inflammation via the secretion of MMP3 in patients with RP. Involvement of proinflammatory cytokines, including IL1β, was suggested for the pathophysiology of airway lesions in patients with RP.