DPP-4 inhibitors repress foam cell formation by inhibiting scavenger receptors through protein kinase C pathway

Acta Diabetol. 2014;51(3):471-8. doi: 10.1007/s00592-013-0541-3. Epub 2013 Dec 22.

Abstract

Studies show that dipeptidyl peptidase-4 (DPP-4) inhibitors may have an anti-atherosclerotic effect. Since foam cells are key components of atherosclerotic plaque, we studied the effect of DPP-4 inhibitors on foam cell formation. Foam cell formation was studied by treatment of THP-1 macrophages with oxidized low-density lipoprotein in the absence or presence of DPP-4 inhibitors (sitagliptin and NVPDPP728). The expression of scavenger receptors SRA, CD36 and LOX-1 was measured, and their role in foam cell formation in the presence of DPP-4 inhibitors was examined. In additional studies, role of protein kinase C and A in the effect of DPP-4 inhibitors was examined. Foam cell formation was markedly reduced by both DPP-4 inhibitors, as was the expression of CD36 and LOX-1 (CD36 ≫ LOX-1), but not SRA. Simultaneously, there was a reduction in phosphorylated PKC, but not PKA, content. Recovery of phosphorylated PKC following treatment of cells negated the effect of DPP-4 inhibitors on foam cell formation. Further, overexpression of CD36 or LOX-1 blocked the effect of DPP-4 inhibitors on foam cell formation. DPP-4 inhibitors repress foam cell formation through the inhibition of SRs CD36 and LOX-1, most likely via the inhibition of PKC activity. This study provides novel insights into the mechanism of inhibition of atherosclerosis by DPP-4 inhibitors.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Atherosclerosis / drug therapy
  • Atherosclerosis / enzymology
  • Atherosclerosis / genetics
  • Atherosclerosis / metabolism
  • Cell Line
  • Dipeptidyl Peptidase 4 / genetics
  • Dipeptidyl Peptidase 4 / metabolism
  • Dipeptidyl-Peptidase IV Inhibitors / pharmacology*
  • Down-Regulation / drug effects
  • Foam Cells / drug effects*
  • Foam Cells / enzymology
  • Foam Cells / metabolism
  • Humans
  • Lipoproteins, LDL / metabolism
  • Macrophages / drug effects
  • Macrophages / enzymology
  • Macrophages / metabolism
  • Protein Kinase C / metabolism*
  • Pyrazines / pharmacology
  • Receptors, Scavenger / genetics*
  • Receptors, Scavenger / metabolism
  • Sitagliptin Phosphate
  • Triazoles / pharmacology

Substances

  • Dipeptidyl-Peptidase IV Inhibitors
  • Lipoproteins, LDL
  • Pyrazines
  • Receptors, Scavenger
  • Triazoles
  • oxidized low density lipoprotein
  • Protein Kinase C
  • DPP4 protein, human
  • Dipeptidyl Peptidase 4
  • Sitagliptin Phosphate