Increased secretion of IP-10 from monocytes under hyperglycemia is via the TLR2 and TLR4 pathway

Cytokine. 2009 Jul;47(1):6-10. doi: 10.1016/j.cyto.2009.02.004. Epub 2009 May 15.

Abstract

Among the chemokines, members of the CXC family include IP-10 (interferon-gamma induced protein of 10kDa). Elevated serum IP-10 levels have been shown in diabetes. However, there is a paucity of data examining the sources and regulation of IP-10 under hyperglycemic conditions and this was the overall aim of the study. Type 1 diabetes (T1DM) is a pro-inflammatory state. We previously demonstrated increased toll like receptor (TLR) 2 and 4 activation in monocytes of T1DM patients. Thus, we also examined the role of the TLR pathway in modulating IP-10 release from human monocytes under hyperglycemia. Also, circulating and monocytic levels of IP-10 in patients with T1DM with and without microvascular complications (T1DM-MV and T1DM) and controls (C) was assessed. Under HG, IP-10 mRNA and protein were significantly increased compared to normoglycemia. Incubation of monocytes with dominant negative Ikb but not control vector significantly abrogated HG-induced IP-10 release. Furthermore, both TLR2 siRNA as well as TLR4 siRNA, either alone or in combination significantly abrogated HG-induced IP-10 release. Serum and monocytic levels of IP-10 were significantly increased in T1DM and T1DM-MV compared to matched controls. Thus, we demonstrate increased circulating and monocytic IP-10 in T1DM. Down-regulation of TLR2 and TLR4 abrogates HG-induced IP-10 release via NF-kappaB inhibition.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adolescent
  • Adult
  • Chemokine CXCL10 / blood
  • Chemokine CXCL10 / genetics
  • Chemokine CXCL10 / metabolism*
  • Diabetes Mellitus, Type 1 / blood
  • Female
  • Gene Expression / drug effects
  • Glucose / pharmacology
  • Humans
  • Hyperglycemia / blood
  • Hyperglycemia / metabolism*
  • I-kappa B Kinase / genetics
  • Lipopolysaccharides / pharmacology
  • Male
  • Middle Aged
  • Monocytes / drug effects
  • Monocytes / metabolism*
  • NF-kappa B / antagonists & inhibitors
  • RNA, Small Interfering / genetics
  • Signal Transduction / physiology*
  • Toll-Like Receptor 2 / genetics*
  • Toll-Like Receptor 4 / genetics*
  • Transfection
  • Young Adult

Substances

  • CXCL10 protein, human
  • Chemokine CXCL10
  • Lipopolysaccharides
  • NF-kappa B
  • RNA, Small Interfering
  • TLR2 protein, human
  • TLR4 protein, human
  • Toll-Like Receptor 2
  • Toll-Like Receptor 4
  • I-kappa B Kinase
  • Glucose