Erythropoietin requires endothelial nitric oxide synthase to counteract TNF-[alpha]-induced microcirculatory dysfunction in murine striated muscle

Shock. 2011 Mar;35(3):315-21. doi: 10.1097/SHK.0b013e3181fd0700.

Abstract

In the present study, we aimed to evaluate whether erythropoietin (EPO) treatment may exert nonhematopoietic endothelial protection against TNF-[alpha]-induced microvascular inflammation and to determine the involvement of the nitric oxide (NO)-producing enzyme isoforms endothelial NO synthase (eNOS) and inducible NO synthase (iNOS). Murine dorsal skinfold chambers of wild-type (WT) animals were topically stimulated with TNF-[alpha] after pretreatment with epoetin beta (1,000 IU/kg body weight i.p.) or physiological saline. Leukocyte behavior, microvascular perfusion, and apoptosis were assessed by in vivo fluorescence microscopy. To study the involvement of NO, we compared eNOS-deficient (eNOS-/-) and iNOS-deficient (iNOS-/-) mice with WT animals. TNF-[alpha]-associated leukocyte activation, perfusion failure, and apoptosis were substantially attenuated in EPO-pretreated WT mice, which was accompanied by marked reduction of perivascular infiltration with F4/80-stained macrophages. The anti-inflammatory protective effects of EPO were abolished in eNOS-/-, but not in iNOS-/- mice, both with unaffected intercellular adhesion molecule 1 expression. However, the antiapoptotic effect of EPO was maintained in both eNOS-/- and iNOS-/- mice, indicating that this mechanism might rather be independent of NO. We conclude that EPO treatment elicits protection against TNF-[alpha]-induced microcirculatory dysfunction, depending on NO derived from endothelial cells, but not on the inducible isoform.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Erythropoietin / pharmacology*
  • Immunoblotting
  • Immunohistochemistry
  • Male
  • Mice
  • Microcirculation / drug effects*
  • Microscopy, Fluorescence
  • Muscle, Striated / drug effects*
  • Nitric Oxide Synthase Type II / metabolism
  • Nitric Oxide Synthase Type III / metabolism*
  • Tumor Necrosis Factor-alpha / pharmacology*

Substances

  • Tumor Necrosis Factor-alpha
  • Erythropoietin
  • Nitric Oxide Synthase Type II
  • Nitric Oxide Synthase Type III