Anti-RBP4 monoclonal antibody, clone C579M

PurposeElevated plasma concentration of retinol binding protein 4 (RBP4) has recently emerged as a potential risk factor as a component of developing metabolic syndrome (MS). Therefore, this study aimed to analyse the relationship between components of MS and concentrations of plasma RBP4 in a population of subjects 65years and older.MethodsThe study sample consisted of 3038 (1591 male) participants of the PolSenior study, aged 65years and older. Serum lipid profile, concentrations of RBP4, glucose, insulin, C-reactive protein, IL-6, and activity of aminotransferases were measured. Nutritional status (BMI/waist circumference) and treatment with statins and fibrates were evaluated. Glomerular filtration rate (eGFR), de Ritis ratio, and fatty liver index (FLI), as well as HOMA-IR were calculated.ResultsOur study revealed a strong relationship between components of MS and RBP4 in both sexes: plasma RBP4 levels were increased in men by at least 3x, and in women by at least 4x. Hypertriglyceridemia was most strongly associated with elevated plasma RBP4 levels. Multivariate, sex-adjusted regression analysis demonstrated that chronic kidney disease [OR 1.86 (95% CI 1.78-1.94)], hypertriglyceridemia [OR 1.52 (1.24-1.87)], hypertension [OR 1.15 (1.12-1.19)], low serum HDL cholesterol [OR 0.94 (0.92-0.97)], and age >80years [OR 0.86 (0.81-0.90)] were each independently associated with RBP4 concentration (all p<0.001).ConclusionsIn Caucasians 65years and older, RBP4 serum levels are associated with a number of components of MS, independent of sex and kidney function. Hypertriglyceridemia as a component of MS is most significantly related to RBP4 concentration.

Craniosynostosis is one of the most common congenital craniofacial deformities and could cause a series of diseases or defects. But the molecular mechanism underlying craniosynostosis is rarely reported. Retinal-binding protein 4 (RBP4) was shown to be involved in osteogenesis and decreased dramatically in prematurely fused suture. To investigate the role of RBP4 in osteogenesis, a cell line stably expressing RBP4 was constructed based on MC3T3-E1 cells and RBP4 overexpression was confirmed at both mRNA level and protein level. Then we found that RBP4 upregulation promoted proliferation of MC3T3-E1 cell and significantly increased alkaline phosphatase activity from day 7 to day 14 in MC3T3-E1 cells. Further, in alizarin red staining assay, RBP4 was shown to increase the deposit of calcium phosphate remarkably from day 14 to day 21 in MC3T3-E1 cells cultured in differentiated medium. This indicated that RBP4 prompted the mineralization of MC3T3-E1 cells. In accordance with this phenotype, we detected the typical osteo-differentiation markers by RT-qPCR and demonstrated that RUNX2, OC, OPN and COLL1 were greatly increased in RBP4-overexpressed MC3T3-E1 cells compared to the control. Therefore, our data suggest that RBP4 plays a positive role during osteogenesis and may be favorable for bone formation. This study provides us a new opinion about the role of RBP4 in craniosynostosis and RBP4 is worth of further study about its application on bone regeneration or bone development.