Pro-inflammatory chemokines CCL2, chemerin, IP-10 and RANTES in human serum during an oral lipid tolerance test

BACKGROUND

There is a strong coincidence of obesity and a chronic state of modest inflammation. Secretion of pro-inflammatory cytokines from adipocytes and immune cells represents a key mechanism in this process and is affected by fatty acids.

MATERIAL AND METHODS

A study cohort of 100 overnight fasted healthy volunteers underwent an oral lipid tolerance test (OLTT) by ingestion of 160ml of a protein- and sugar-free lipid emulsion of defined composition. Venal blood was drawn at 0h (fasting) and at 2, 4, and 6h after lipid ingestion. Subjects were characterized by anthropometric and standard laboratory parameters. Serum concentrations of CCL2, IP-10, chemerin, and RANTES were measured by enzyme-linked immunosorbent assay (ELISA). Murine 3T3-L1 adipocytes were stimulated with free fatty acids (FA) and with sex steroids and concentrations of CCL2 and chemerin in cell culture supernatants were measured by ELISA.

RESULTS

A significant reduction of circulating CCL2, IP-10, and chemerin concentrations was observed as a consequence of triglyceride ingestion whereas RANTES levels were increased. CCL2 serum concentrations were positively correlated with resistin and visfatin levels and with LDL/HDL ratio and negatively with adiponectin. There were significant differences in chemerin and RANTES serum concentrations in female and male subjects. CCL2 secretion from 3T3-L1 adipocytes was inhibited by treatment with linoleic (LA) and oleic acid (OA) whereas chemerin secretion was induced. Chemerin release from 3T3-L1 adipocytes was inhibited by testosterone.

CONCLUSIONS

Oral lipid loading is linked to reduced circulating pro-inflammatory chemokines CCL2, IP-10, and chemerin and to increased RANTES levels, suggesting that dietary lipids affect immune function.