Lipoprotein(a), lipids and proinflammatory cytokines in patients undergoing major abdominal surgery

The aims were to investigate whether surgical stress can induce a positive or negative lipoprotein(a) acute response, to determine any association with apolipoprotein(a) phenotypes, and to establish whether any such response is dependent on changes in lipids and proinflammatory cytokines. In addition, the impact of interleukin (IL) 6 genetic variability on the cytokine response to surgery was examined.

This prospective, observational study included 41 patients with cancer referred for abdominal surgery. Preoperative (T0) plasma concentrations of lipoprotein(a), IL-6, tumour necrosis factor alpha, and serum concentrations of transforming growth factor beta1 and lipids, were compared with values obtained 5 h (T1), 24 h (T2) and 5 days (T3) after surgery. Apolipoprotein(a) Kringle IV (KIV)-VNTR (variable-number tandem repeat) and IL-6 - 174 G/C polymorphisms were analysed.

Lipoprotein(a) was found to act as a negative acute-phase reactant (30.0 per cent reduction at T2) (P = 0.009). Surgery had a more profound impact on subjects with low KIV-VNTR. After surgery, lipoprotein(a) correlated significantly with corrected low-density lipoprotein (LDL)-cholesterol (r = 0.408 at T2). IL-6 inversely correlated with lipoprotein(a) (r = -0.321 at T1) and LDL-cholesterol (r = -0.418 at T1). The IL-6 response could be predicted from a combination of the surgical severity and -174 G/C genotype.

Although temporal associations did not indicate causality, these data provide a hypothesis to explain the inverse relationship between lipoprotein(a) and IL-6.