Energy-Restricted High-Fat Diets Only Partially Improve Markers of Systemic and Adipose Tissue Inflammation

Oncostatin M (OSM) is a multifunctional gp130 cytokine. Although OSM is produced in adipose tissue, it is not produced by adipocytes. OSM expression is significantly induced in adipose tissue from obese mice and humans. The OSM-specific receptor, OSM receptor β (OSMR), is expressed in adipocytes, but its function remains largely unknown. To better understand the effects of OSM in adipose tissue, we knocked down Osmr expression in adipocytes in vitro using siRNA. In vivo, we generated a mouse line lacking Osmr in adiponectin-expressing cells (OSMRFKO mice). The effects of OSM on gene expression were also assessed in vitro and in vivo. OSM exerts proinflammatory effects on cultured adipocytes that are partially rescued by Osmr knockdown. Osm expression is significantly increased in adipose tissue T cells of high fat-fed mice. In addition, adipocyte Osmr expression is increased following high fat feeding. OSMRFKO mice exhibit increased insulin resistance and adipose tissue inflammation and have increased lean mass, femoral length, and bone volume. Also, OSMRFKO mice exhibit increased expression of Osm, the T cell markers Cd4 and Cd8, and the macrophage markers F4/80 and Cd11c. Interestingly, the same proinflammatory genes induced by OSM in adipocytes are induced in the adipose tissue of the OSMRFKO mouse, suggesting that increased expression of proinflammatory genes in adipose tissue arises both from adipocytes and other cell types. These findings suggest that adipocyte OSMR signaling is involved in the regulation of adipose tissue homeostasis and that, in obesity, OSMR ablation may exacerbate insulin resistance by promoting adipose tissue inflammation.

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Nitrate attenuates high fat diet‐induced glucose intolerance in association with reduced epididymal adipose tissue inflammation and mitochondrial reactive oxygen species emission

The Journal of Physiology ◽

10.1113/jp279455 ◽

2020 ◽

Vol 598 (16) ◽

pp. 3357-3371 ◽

Cited By ~ 2

Author(s):

Henver S. Brunetta ◽

Valerie Politis‐Barber ◽

Heather L. Petrick ◽

Kaitlyn M. J. H. Dennis ◽

Aleah J. Kirsh ◽

...

Keyword(s):

Reactive Oxygen Species ◽

Adipose Tissue ◽

Glucose Intolerance ◽

High Fat Diet ◽

Epididymal Adipose Tissue ◽

Oxygen Species ◽

Adipose Tissue Inflammation ◽

Mitochondrial Reactive Oxygen Species ◽

High Fat ◽

Tissue Inflammation

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The triglyceride synthesis enzymes DGAT1 and DGAT2 have distinct and overlapping functions in adipocytes

The Journal of Lipid Research ◽

10.1194/jlr.m093112 ◽

2019 ◽

Vol 60 (6) ◽

pp. 1112-1120 ◽

Cited By ~ 18

Author(s):

Chandramohan Chitraju ◽

Tobias C. Walther ◽

Robert V. Farese

Keyword(s):

Adipose Tissue ◽

High Fat Diet ◽

Convergent Evolution ◽

Metabolic Energy ◽

Chow Diet ◽

High Fat ◽

Functional Differences ◽

High Fat Diets ◽

Fat Stores ◽

Fat Diets

Mammals store metabolic energy as triacylglycerols (TGs) in adipose tissue. TG synthesis is catalyzed by the evolutionarily unrelated acyl-CoA:diacylglycerol acyltransferase (DGAT) enzymes DGAT1 and DGAT2, which catalyze the same reaction and account for nearly all TG synthesis. The reasons for their convergent evolution to synthesize TGs remain unclear. Mice lacking DGAT1 are viable with reduced fat stores of TGs, whereas DGAT2 KO mice die postnatally just after birth with >90% reduction of TGs, suggesting that DGAT2 is the predominant enzyme for TG storage. To better understand the functional differences between the DGATs, we studied mice fed chow or high-fat diets lacking either enzyme in adipose tissue. Unexpectedly, mice lacking DGAT2 in adipocytes have normal TG storage and glucose metabolism on regular or high-fat diets, indicating DGAT2 is not essential for fat storage. In contrast, mice lacking DGAT1 in adipocytes have normal TG storage on a chow diet but moderately decreased body fat accompanied by glucose intolerance when challenged with a high-fat diet. The latter changes were associated with the activation of ER stress pathways. We conclude that DGAT1 and DGAT2 can largely compensate for each other for TG storage but that DGAT1 uniquely has an important role in protecting the ER from the lipotoxic effects of high-fat diets.

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Luteolin Improves Insulin Resistance in Postmenopausal Obese Mice by Altering Macrophage Polarization (FS12-01-19)

Current Developments in Nutrition ◽

10.1093/cdn/nzz049.fs12-01-19 ◽

2019 ◽

Vol 3 (Supplement_1) ◽

Cited By ~ 1

Author(s):

Yunjung Baek ◽

Mi Nam Lee ◽

Dayong Wu ◽

Munkyong Pae

Keyword(s):

Insulin Resistance ◽

Body Weight ◽

Adipose Tissue ◽

High Fat Diet ◽

Ovarian Function ◽

Body Weight Gain ◽

Adipose Tissue Inflammation ◽

High Fat ◽

Tissue Inflammation ◽

Ovariectomized Mice

Abstract Objectives Previously, we showed that loss of ovarian function in mice fed high-fat diet exacerbated insulin resistance and adipose tissue inflammation. In the current study, we tested whether consumption of luteolin, an anti-inflammatory flavonoid, could mitigate adipose tissue inflammation and insulin resistance in obese ovariectomized mice. Methods Nine-week-old ovariectomized C57BL/6 mice were fed a low-fat diet (LFD), high-fat diet (HFD), or HFD supplemented with 0.005% luteolin (HFD + L) for 16 weeks. The anti-inflammatory drug salicylate was used as a positive control. Fasting blood glucose, insulin, and insulin resistance index HOMA-IR were measured every 4 weeks. Adipose tissue and spleen were characterized for tissue inflammation by real-time PCR and immune cell populations by flow cytometry after 16 weeks of feeding. Results HFD resulted in more body weight gain than LFD in ovariectomized mice and supplementing HFD with 0.005% luteolin did not affect the body weight gain. In addition, HFD elicited a significant elevation in fat mass, which were comparable between HFD and HFD + L groups. However, luteolin supplementation resulted in a significant decrease in CD11c+ macrophages in gonadal adipose tissue, as well as a trend of decrease in macrophage infiltration. Luteolin supplementation also significantly decreased mRNA expression of inflammatory and M1 markers MCP-1, CD11c, TNF-a, and IL-6, while maintaining expression of M2 marker MGL1. We further found that luteolin treatment protected mice from insulin resistance induced by HFD consumption; this improved insulin resistance was correlated with reductions in CD11c+ adipose tissue macrophages. Conclusions Our findings indicate that dietary luteolin supplementation attenuates adipose tissue inflammation and insulin resistance found in mice with loss of ovarian function coupled with a HFD intake, and this effect may be partly mediated through suppressing M1-like polarization of macrophages in adipose tissue. These results have clinical implication in implementing dietary intervention for prevention of metabolic syndrome associated with postmenopause and obesity. Funding Sources Supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (NRF-2018R1A1A1A05078886).

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