Increased level of Complement C3 in patients with osteoporosis and enhanced osteogenic ability in osteoblasts with Complement component 3 knockdown

Abstract

Objective(s):Complement C3 has the potential to impact bone homeostasis. The purpose of this study is to determine the difference in serum Complement C3 levels between osteoporosis patients and non-osteoporosis patients, as well as how Complement C3 silencing impacts and works on osteoblast osteogenesis.Materials and Methods: 58 people who underwent dual energy X-ray bone mineral densit(BMD) measurement in The Second Affiliated Hospital of Zhejiang Chinese Medical University from June to September 2021 were analyzed retrospectively. According to the classification of BMD t value, the subjects were divided into 31 cases in osteoporosis group and 27 cases in non- osteoporosis group. Complement C3 levels were recorded. and compared between the two groups. Then, the Complement C3 knockdown lentivirus was used to transfect Raji. The Raji-osteoblast line MG63 co-culture system was constructed after the stable strain was screened. CCK-8 and flow cytometry were used to assess the proliferation and apoptosis of MG63, alkaline phosphatase (ALP) activity was used to evaluate the osteogenic ability of MG63, and RT-PCR was used to assess the expression level of osteoprotegerin（OPG）of MG63.Results:Complement C3 levels in osteoporosis patients' serum are elevated，the proliferation level and osteogenic ability of MG63 were improved in Complement C3 knockdown Raji-osteoblast MG63 co-culture system. Furthermore, OPG expression in MG63 was enhanced.Conclusion:To sum it up, the level of Complement C3 in the serum of osteoporosis patients is elevated.Knocking down Complement C3 boost osteoblast osteogenic ability, which may be achieved by controlling OPG / RANKL / RANK system.

A Brief Review of Bone Cell Function and Importance

“…On the other hand, its receptor, C3aR, is expressed during the differentiation of human mesenchymal stem cells (MSCs) into mature osteoblasts, suggesting that C3a may play a role in both osteoblast differentiation (promoting osteoblastogenesis) and bone resorption. C3 deficiency has been associated with certain autoimmune conditions, such as systemic lupus erythematosus [43,62].…”