Interleukin-6 May Not Affect Bone Resorption Marker CTX or Bone Formation Marker P1NP in Humans

Context Interleukin 6 (IL-6) contributes to bone remodeling in preclinical studies. Clinical trials investigating the role of IL-6 in bone remodeling are limited. Objective To investigate if IL-6 regulates bone remodeling in humans. Design Plasma concentrations of the bone resorption marker carboxy-terminal type I collagen crosslinks (CTX) and of the bone formation marker procollagen type 1 N-terminal propeptide (P1NP) were measured during a mixed-meal tolerance test (MMTT) in 3 placebo-controlled human studies. Participants Five healthy individuals participated in study 1; 52 obese individuals, in study 2; and 10 healthy individuals, in study 3. Interventions Study 1 was a single-blinded crossover study consisting of a 1-h infusion of saline (placebo) or the IL-6 receptor antibody tocilizumab followed by an exercise bout. Study 2 was a randomized, double-blinded 12-week exercise training intervention study. Participants received infusions of saline or tocilizumab. Study 3 was a randomized, double-blinded, crossover study consisting of 30 min infusion of saline or IL-6. Main outcomes measures Effect of IL-6 on CTX levels. Results CTX was significantly (P < 0.01) decreased during MMTTs in all 3 studies. Treatment with tocilizumab did not affect exercise or meal induced changes in plasma CTX or P1NP concentrations acutely (study 1) or after a 12-week treatment period (study 2). Exogenous IL-6 had no effect on CTX or P1NP plasma concentrations (study 3). Conclusions IL-6 may not regulate bone remodeling in humans.

Biochemical Markers of Bone Turnover in Rheumatoid Arthritis Patients Treated with Glucocorticoids

Osteocalcin and deoxypyridinoline levels were measured in 55 RA patients during and after glucocorticoid therapy with prednisone, methylprednisolone and cortisone. A decrease of 27% of the bone resorption marker deoxypyridinoline (from 10.13 to 7.4) and an increase of 23% of the bone formation marker osteocalcin (from 16.3 to 20.1) were also clinically confirmed by the presence of osteoporosis in 74% of patients receiving corticosteroid treatment as compared with only 31% in the control group.