Inflammatory cytokines in fracture healing: involvement and analysis

IntroductionThe importance of the interplay of both skeletal and immune systems is reflected by the emerging interdisciplinary research field, called osteoimmunology, focused on common aspects of osteology and immunology. Many segnaling molecules, such as transcription factors, membrane receptors, IL-6 and TNF-α, are involved in the bone remodelling. The purpose of this study was to evaluate markers of bone metabolism and cytokines in patients with fragility fractures compared to osteoporotic patients. Materials and methods We enrolled 37 subjects with a femoral neck fracture and 47osteoporotic outpatients . Blood samples are drawing 24h before and after surgery (Group A) and at the first examination for outpatients (Group B). All the patients underwent DEXA examination (T-score <-2.5) to measure BMD. For bone metabolism were measured Ca, P, vitamin D, PTH, CTX, ALP and osteocalcin using ECL technology (Modular E, Roche, Basel, Switzerland). IL-1, IL-6, TNF-α and IL-10 concentrations were evaluated by ELISA assay (R&D Systems, Inc. Minneapolis, USA). Statistical analysis were performed using t-test. Results Statistical differences were observed in vitamin D, PTH and CTX concentrations. Group A showed a decrease in Vitamin D (p<0.001) whereas PTH and CTX were increase (p≤ 0.001). About cytokine concentrations Group A (before surgery) showed a significant increase in IL-6, TNF-α and IL-10 (respectively p<0.0001, p<0.0001 and p=0.01) respect Group B. The different implant used lead to a change, IL-6 and IL-10 increased after surgery in intramedullary nail patients Vs prosthesis, significant difference were respectively p<0.001 and p<0.05. Discussion The inflammatory mediators are involved not only in several aspects of physiological bone remodeling but also in pathological bone disorders. The higher cytokines levels observed in fractured patients suggest an inflammatory condition which lead to bone weakness, this hypothesis may be supported by the results obtained in Vitamin D, PTH and CTX (1). The results obtained in surgery treatment with prosthesis give a reduction in systemic cytokines concentrations. Inflammatory cytokines could be used to identify high-risk fracture patients, further study need to confirm their role in fracture healing. 1)Lacativa PG, Farias ML. Osteoporosis and inflammation. Arq Bras Endocrinol Metabol. 2010 Mar;54(2):123-32 2) Pacifici R. The immune system and bone. Arch Biochem Biophys. 2010 Jun 17