Studies Of Different Bone Geometry And Circulating Monocytes Gene Expression Profiles In Overweight Adults

Obesity results from the excessive accumulation of fat thatexceeds the body's skeletal and physical standards. Obesitywill reduce the risk of osteoporotic fracture, but increasemortality of several life-threatening diseases including Type2 diabetes, cardiovascular disease, gallbladder disease, andgastrointestinal cancers. Our studies revealed the influenceof obesity to human physiological functions from two aspectsincluding bone geometry and immune cells.At first, we performed studies focusing on therelationships between bone geometry and body composition. Wedemonstrate the possible reasons from bone structures whyoverweight or obese populations have lower OF risk, throughexploring the bone geometry differences and body compositiondetermination in overweight subjects. We recruited 400subjects aged 20 to 40, with 100 overweight and 100 underweightsubjects for women and men respectively. Bone geometricparameters including subperiosteal diameter (W), sectionmodulus (Z), cross-section area (CSA) and buckling ratio (BR)can be inferred from Dual energy X-ray absorptiometry (DXA)measurements for BMD and bone size. Multiple regression modelswere used to compare the TBLM, TBFM and bone geometricparameters between the overweight and underweight groups, andto analyze how total body lean mass (TBLM) and total body fatmass (TBFM) contribute to the variations of bone geometricparameters. Results revealed that overweight subjects in our sample have higher bone bending strength and axial strength,but almost the same W after adjustment for age and height. Inaddition, bone geometry may adapt primarily to mechanical loadas represented by TBLM, but TBFM seemed to have no independenteffect on the bone geometry in Chinese overweight subjects. Ourdata identify the positive association of TBLM and bonestrength in Chinese overweight adults.Secondly, we explored the different expression profiles ofcirculating monocytes between overweight and healthy subjectsby microarray analyses. Through comparison of monocytes genesexpression profiles between 5 overweight women subjects and 5controls, we found 61 differential expressed genes (31 genesup-regulated and 30 genes down-regulated in overweight group).These genes mainly involved in biological process regulation,cell communication, establishment of localization and celladherence etc. KEGG pathway analyses results revealed thatseveral important pathways associated with obesity for thesedifferential expressed genes, including MAPK signaling pathway,Insulin signaling pathway, PPAR signaling pathway, Celladhesion molecules (CAMs) and Jak-STAT signaling pathway etc.We also found some key regulators of cholesterol metabolism andtransfer (HMGCR,APOM), and key enzymes in cell proliferation(GGPS1). It might explain the higher risk of atherosclerosisand cardiovascular diseases in obese populations.