IL1β and TNFα differently modulate CXCL13 chemokine in stromal cells and osteoblasts isolated from osteoarthritis patients: evidence of changes associated to cell maturation

Bone homeostasis is regulated by cells at different stages of maturation that are influenced by soluble factors. The modulatory function of two pro-inflammatory cytokines, IL-1β and TNF-α, on the expression of CXCL13 chemokine was evaluated in osteoblasts (OB) and bone marrow stromal cells (BMSC) from osteoarthritis (OA) and post-traumatic (PT) patients. In basal condition, CXCL13 production by both BMSC and OB was significantly higher in OA than in PT patients. IL1β, significantly induced CXCL13 production in differentiated OB, both from OA and PT patients, but not in BMSC from both either group. TNFα reduced CXCL13 production only in BMSC from OA patients. The combination of IL1β and TNFα increased CXCL13 production only in OB in the same amount as for IL-1β alone. OB from OA released a higher amount of CXCL13 compared to PT in all conditions tested. CD121a (IL1 receptor type I) was highly expressed only by OB. Moreover, in bone tissue biopsies CXCL13 was expressed by mesenchymal and mononuclear cells. This study demonstrates that cells at different stages of maturation (BMSC and OB) and derived from physiological (PT) or pathological conditions (OA) respond in different ways to inflammatory stimuli. These data may contribute to understand the basic maturation processes of bone cells in old patients.