Reduction in serum apoB is associated with reduced inflammation and insulin resistance in post-menopausal women: A MONET study.

Objective: Large inter-individual variations exist in changes in inflammation and insulin resistance (IR) in response to hypocaloric-interventions in obese subjects that are not explained by weight-loss per se. We identified the number of serum apoB-lipoproteins (serum apoB) as the primary predictor of inflammatory markers in post-menopausal overweight/obese women. As apoB-lipoproteins are related to inflammation and inflammation promotes IR, we hypothesized that the reduction in inflammation and IR following hypocaloric-interventions is associated with the reduction in serum apoB.

Methods/results: After a 6-month hypocaloric-dietary-intervention in 56 overweight/obese post-menopausal women, there was a significant reduction in weight, total, subcutaneous abdominal and visceral abdominal fat mass, apoB, Lp(a), hsCRP, orosomucoid, haptoglobin and IR (increased M(clamp)) and an increase in LDL-C/apoB ratio. In regression analysis, % change in apoB was the primary predictor of % changes in hsCRP (R(2)=0.22), orosomucoid (R(2)=0.35), haptoglobin (R(2)=0.43) and M(clamp) (R(2)=0.17). When the study population was split around baseline median apoB (0.97g/L), women who were above median apoB (N=27) had significant reduction in apoB (-17%), hsCRP (-24%), orosomucoid (-8%), haptoglobin (-18%) and IR (M(clamp) +14%). On the other hand, women below median apoB (N=29) had no significant changes in these parameters despite equivalent reduction in weight and fat depots in the two groups.

Conclusion: Reduction in apoB associated strongly and independently with the reduction in inflammatory markers and IR following a hypocaloric-diet in overweight/obese women. We hypothesize that the elevated apoB phenotype may be key therapeutic target to reduce obesity-associated inflammation and IR maximally by hypocaloric-dietary-interventions.