[HTML][HTML] Myeloid heme oxygenase-1 haploinsufficiency reduces high fat diet-induced insulin resistance by affecting adipose macrophage infiltration in mice

JY Huang, MT Chiang, SF Yet, LY Chau - PloS one, 2012 - journals.plos.org
JY Huang, MT Chiang, SF Yet, LY Chau
PloS one, 2012journals.plos.org
Increased adipose tissue macrophages contribute to obesity-induced metabolic syndrome.
Heme oxygenase-1 (HO-1) is a stress-inducible enzyme with potent anti-inflammatory and
proangiogenic activities in macrophages. However, the role of macrophage HO-1 on obesity-
induced adipose inflammation and metabolic syndrome remains unclear. Here we show that
high-fat diet (HFD) feeding in C57BL/6J mice induced HO-1 expression in the visceral
adipose tissue, particularly the stromal vascular fraction. When the irradiated C57BL/6J mice …
Increased adipose tissue macrophages contribute to obesity-induced metabolic syndrome. Heme oxygenase-1 (HO-1) is a stress-inducible enzyme with potent anti-inflammatory and proangiogenic activities in macrophages. However, the role of macrophage HO-1 on obesity-induced adipose inflammation and metabolic syndrome remains unclear. Here we show that high-fat diet (HFD) feeding in C57BL/6J mice induced HO-1 expression in the visceral adipose tissue, particularly the stromal vascular fraction. When the irradiated C57BL/6J mice reconstituted with wild-type or HO-1+/− bone marrow were fed with HFD for over 24 weeks, the HO-1+/− chimeras were protected from HFD-induced insulin resistance and this was associated with reduced adipose macrophage infiltration and angiogenesis, suggesting that HO-1 affects myeloid cell migration toward adipose tissue during obesity. In vivo and in vitro migration assays revealed that HO-1+/− macrophages exhibited an impaired migration response. Chemoattractant-induced phosphorylation of p38 and focal adhesion kinase (FAK) declined faster in HO-1+/− macrophages. Further experiments demonstrated that carbon monoxide and bilirubin, the byproducts derived from heme degradation by HO-1, enhanced macrophage migration by increasing phosphorylation of p38 and FAK, respectively. These data disclose a novel role of hematopoietic cell HO-1 in promoting adipose macrophage infiltration and the development of insulin resistance during obesity.
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