Abstract
Aims: Obesity is characterized as a chronic state of low-grade inflammation with progressive immune cell infiltration into adipose tissue. Adipose tissue macrophages play a critical role in the establishment of chronic inflammatory states and metabolic dysfunctions. Inonotus (I.) sanghuang and its extract polyphenols exhibit anti-carcinogenesis, anti-inflammatory, and anti-oxidant activities. However, the action of I. sanghuang polyphenols in obesity-related inflammation has not been reported. The aim of this study was to explore the anti-inflammatory action of polyphenols from I. sanghuang extract (ISE) in macrophages and the interaction between macrophages and adipocytes.Materials and Methods: RAW264.7 macrophages were stimulated with LPS or conditioned medium of hypertrophied 3T3-L1 adipocytes or cocultured with differentiated adipocytes in the presence of different doses of ISE. The inflammatory cytokines were evaluated by ELISA, the MAPK, NF-κB, and IL-6/STAT3 signals were determined by immunoblotting, and the migrated function of macrophages was determined by migration assay.Results: ISE suppressed the inflammatory mediators including NO, TNF-α, IL-6, and MCP-1 induced by either LPS or conditioned medium derived from 3T3-L1 adipocytes. ISE also decreased the production of these inflammatory mediators in cocultures of 3T3-L1 adipocytes and RAW264.7 macrophages. Furthermore, ISE blocked RAW264.7 macrophages migration toward 3T3-L1 adipocytes in cocultures. Finally, this effect of ISE might be mediated via inhibiting ERK, p38, and STAT3 activation.Conclusions: Our findings indicate the possibility that ISE suppresses the interaction between macrophages and adipocytes, attenuates chronic inflammation in adipose tissue and improves obesity-related insulin resistance and complication, suggesting that ISE might be a valuable medicinal food effective in improving insulin resistance and metabolic syndrome.
Highlights
Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have a negative effect on health
We investigated the anti-inflammatory property of I. sanghuang extract (ISE) on RAW264.7 macrophages and explored the effect of ISE on the crosstalk between RAW264.7 macrophages and 3T3-L1 adipocytes using in vitro cell coculture models
To investigate whether ISE affects the production of proinflammatory mediators from macrophages in obesity-related environments, RAW264.7 cells were treated with different doses of ISE in the presence or absence of LPS
Summary
Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have a negative effect on health. Does obesity affect health, and the complications it causes have become some of the main disease burdens worldwide. The metabolic response to obesity is diverse; a growing amount of evidence suggests that there is a considerable proportion of obese individuals that lack obesity-associated diseases and are metabolically healthy [4]. Inflammation is one of the causes that distinguish metabolically healthy from metabolically unhealthy obesity. Obesity-related inflammation is mainly caused by cytokines secreted from adipose tissue macrophages (ATMs) [5]. Inflammation that ATMs drive links obesity to insulin resistance, which is a central mechanism in obesity-associated diseases such as T2DM and metabolic syndrome [6]. ATMs are crucial mediators of meta-inflammation, insulin resistance, metabolic dysfunction, and have other bad influences on adipocyte function [7]
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