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Deactivation of 12‐HETE by Peroxisomal β‐Oxidation by Alternatively Activated Macrophages
Author(s) -
Kriska Tamas,
Campbell William B.
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.827.16
Subject(s) - peroxisome , chemistry , metabolite , catabolism , biochemistry , arachidonic acid , beta oxidation , inflammation , metabolism , biology , enzyme , immunology , receptor
Polarization of macrophages to pro‐inflammatory M1 and to anti‐inflammatory or alternatively activated M2 state has important physiological implications in development of experimental hypertension and inflammation. 12‐ and 15‐hydroxyeicosatetraenoic acids (12‐ and 15‐HETE), the two major arachidonic acid metabolites of 12/15‐lipoxygenase, are essential in the process since the disruption of the encoding gene, Alox15, renders the mice unsusceptible to variety of types of experimental hypertension. The objective of this study was to test the hypothesis that alternatively activated M2 macrophages catabolize 12‐HETE into products that do not enhance angiotensin II‐mediated arterial constriction. We used cultures of M1‐ or M2‐polarized macrophages to study the metabolism of externally added [ 14 C]‐12‐HETE. The 12‐HETE metabolites were separated by a reverse phase HPLC and identified by mass spectrometry. M2 polarized peritoneal macrophages converted most of the 12‐HETE into more polar metabolites within 2 hours of incubation. M1 macrophages, however, had little effect on the 12‐HETE catabolism. The same effect was observed in cultures of M1 or M2 polarized bone marrow‐derived macrophages. The major metabolite peaks were identified by mass‐spectrometry as β‐oxidation products. The conversion of 12‐HETE was inhibited by 50 μM thioridazine, a peroxisomal β‐oxidation inhibitor. Mitochondrial β‐oxidation inhibitors, 4‐pentenoic acid and etomoxir, had no effect on conversion. qPCR analysis of peroxisomal and mitochondrial β‐oxidation markers confirmed that only peroxisomal markers were upregulated upon M2 polarization. The major 12‐HETE metabolite peaks were collected and their activities were tested on abdominal aortic rings. While 12‐HETE (100 nM) pre‐incubation enhanced constrictions to angiotensin II (1–100 nM) from 15 % to 25 %, the metabolites lacked such an activity. Our results indicate that alternatively activated M2 macrophages are capable of degrading 12‐HETE and eliminating 12‐HETE's enhancement of angiotensin II‐induced vascular constriction, while M1 macrophages are not. These data support an antihypertensive role of M2 macrophages. Support or Funding Information This research was supported by the grant: NIH HL103673