Regulation of monocyte chemoattractant protein 1 (MCP-1) release by explants of human visceral adipose tissue

BACKGROUND: Monocyte chemoattractant protein-1 ( MCP-1) is a chemokine involved in monocyte recruitment during inflammation whose plasma level is elevated in obesity. OBJECTIVE: The present studies were designed to examine the release of MCP-1 in primary culture by explants of visceral adipose tissue from morbidly obese women. RESULTS: Most of the MCP-1 released by adipose tissue explants was derived from the nonfat cells in adipose tissue. The release of MCP-1 by adipose tissue explants was upregulated almost five-fold between 3 and 48 h of incubation. Approximately half of this upregulation was due to the release of endogenous tumor necrosis factor alpha (TNF alpha) and IL-1 beta based on the ability of a combination of a soluble TNF alpha receptor (etanercept) and a blocking antibody against IL-1 beta to reduce MCP-1 release. The release of MCP-1 over 48 h was unaffected by insulin or dexamethasone but significantly reduced by the combination of both agents. MCP-1 release was reduced by 60% in the presence of an inhibitor of the nuclear factor kappa B (NF-kappa B) pathway. There were no significant effects of inhibitors of p44/42 mitogen-activated protein kinase (ERK), Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase ( p38 MAPK) pathways on MCP-1 release. However, inhibition of MCP-1 release in the presence of inhibitors of both the p38 MAPK and NF-kappa B pathways was greater than that seen with only the NF-kappa B inhibitor. DISCUSSION: The present data shows that MCP-1 formation is upregulated over a 48-h incubation of primary explants of visceral adipose tissue. Half of this upregulation is dependent upon endogenous TNF alpha and ll-1 beta and involves the p38 MAPK and NF-kappa B pathways.