Downregulation of complement C3 and C3aR expression in subcutaneous adipose tissue in obese women.
ABSTRACT: The central component of the complement system, C3, is associated with obesity, metabolic syndrome and cardiovascular disease however the underlying reasons are unknown. In the present study we evaluated gene expression of C3, the cleavage product C3a/C3adesArg and its cognate receptor C3aR in subcutaneous and omental adipose tissue in women.Women (n?=?140, 21-69 years, BMI 19.5-79 kg/m2) were evaluated for anthropometric and blood parameters, and adipose tissue gene expression.Subjects were separated into groups (n?=?34-36) according to obesity: normal/overweight (?30 kg/m2), obese I (?45 kg/m2), obese II (?51 kg/m2), and obese III (?80 kg/m2). Overall, while omental expression remained unchanged, subcutaneous C3 and C3aR gene expression decreased with increasing adiposity (2-way ANOVA, p<0.01), with a concomitant decrease in SC/OM ratio (p<0.001). In subcutaneous adipose, both C3 and C3aR expression correlated with apoB, and apoA1 and inversely with waist circumference and blood pressure, while C3aR also correlated with glucose (p<0.05-0.0001). While omental C3aR expression did not correlate with any factor, omental C3 correlated with waist circumference, glucose and apoB (all p<0.05). Further, while plasma C3a/C3adesArg increased and adiponectin decreased with increasing BMI, both correlated (C3a negatively and adiponectin positively) with subcutaneous C3 and C3aR expression (p<0.05-0.001) or less).The obesity-induced down-regulation of complement C3 and C3aR which is specific to subcutaneous adipose tissue, coupled to the strong correlations with multiple anthropometric, plasma and adipokine variables support a potential role for complement in immunometabolism.
Project description:The anaphylatoxin C3a triggers inflammation by binding to its specific G-protein-coupled C3a receptor (C3aR). Since the number of C3aR, which is expressed on the cell surface, affects the response to C3a, we investigated the expression levels of C3aR on human M2 macrophages in allergic situations where high levels of the Th2 cytokine IL-4 and histamine are present in a local microenvironment. The histamine H1 receptor (H1R), H2R and the H4R mRNA expressions were induced or up-regulated during the differentiation process of M2 macrophages. The presence of histamine or agonists targeting the H1R, H2R and, in particular, the H4R during in vitro differentiation from monocytes to macrophages modified the M2 phenotype by regulating the macrophage differentiation marker CD68 and CD163 expressions. In -addition, the C3aR expression was also down-regulated by -ST-1006 during this process. Histamine and ST-1006 down-regulated the expression of C3aR with different time kinetics on fully differentiated M2 macrophages. By analysing C3a-induced IL-6 mRNA expression, we observed a diminished response to C3a in ST-1006-treated M2 macrophages when compared to un-treated cells. Expression of C3 was not affected by histamine, whereas IL-4 strongly down-regulated C3aR and C3 expressions. Our data suggests that down-regulation of C3aR expression by mediators present in allergic situations such as IL-4 or histamine has an anti-inflammatory impact by reducing the sensitivity to C3a-induced down-stream signaling, thereby contributing to the regulation of local inflammatory responses in the skin.
Project description:Occurrence of oxidative stress in white adipose tissues contributes to its dysfunction and the development of obesity-related metabolic complications. Coenzyme Q10 (CoQ10) is the single lipophilic antioxidant synthesized in humans and is essential for electron transport during mitochondrial respiration. To understand the role of CoQ10 in adipose tissue physiology and dysfunction, the abundance of the oxidized and reduced (CoQ10red) isoforms of the CoQ10 were quantified in subcutaneous and omental adipose tissues of women covering the full range of BMI (from 21.5 to 53.2 kg/m(2)). Lean women displayed regional variations of CoQ10 redox state between the omental and subcutaneous depot, despite similar total content. Obese women had reduced CoQ10red concentrations in the omental depot, leading to increased CoQ10 redox state and higher levels of lipid hydroperoxide. Women with low omental CoQ10 content had greater visceral and subcutaneous adiposity, increased omental adipocyte diameter, and higher circulating interleukin-6 and C-reactive protein levels and were more insulin resistant. The associations between abdominal obesity-related cardiometabolic risk factors and CoQ10 content in the omental depot were abolished after adjustment for omental adipocyte diameter. This study shows that hypertrophic remodeling of visceral fat closely relates to depletion of CoQ10, lipid peroxidation, and inflammation.
Project description:Protein expression studies based on the two major intra-abdominal human fat depots, the subcutaneous and the omental fat, can shed light into the mechanisms involved in obesity and its co-morbidities. Here we address, for the first time, the identification and validation of reference proteins for data standardization, which are essential for accurate comparison of protein levels in expression studies based on fat from obese and non-obese individuals.To uncover adipose tissue proteins equally expressed either in omental and subcutaneous fat depots (study 1) or in omental fat from non-obese and obese individuals (study 2), we have reanalyzed our previously published data based on two-dimensional fluorescence difference gel electrophoresis. Twenty-four proteins (12 in study 1 and 12 in study 2) with similar expression levels in all conditions tested were selected and identified by mass spectrometry. Immunoblotting analysis was used to confirm in adipose tissue the expression pattern of the potential reference proteins and three proteins were validated: PARK7, ENOA and FAA. Western Blot analysis was also used to test customary loading control proteins. ENOA, PARK7 and the customary loading control protein Beta-actin showed steady expression profiles in fat from non-obese and obese individuals, whilst FAA maintained steady expression levels across paired omental and subcutaneous fat samples.ENOA, PARK7 and Beta-actin are proper reference standards in obesity studies based on omental fat, whilst FAA is the best loading control for the comparative analysis of omental and subcutaneous adipose tissues either in obese and non-obese subjects. Neither customary loading control proteins GAPDH and TBB5 nor CALX are adequate standards in differential expression studies on adipose tissue. The use of the proposed reference proteins will facilitate the adequate analysis of proteins differentially expressed in the context of obesity, an aim difficult to achieve before this study.
Project description:Exposure to cigarette smoke can initiate sterile inflammatory responses in the lung and activate myeloid dendritic cells (mDCs) that induce differentiation of T helper type 1 (Th1) and Th17 cells in the emphysematous lungs. Consumption of complement proteins increases in acute inflammation, but the contribution of complement protein 3 (C3) to chronic cigarette smoke-induced immune responses in the lung is not clear. Here, we show that following chronic exposure to cigarette smoke, C3-deficient (C3(-/-)) mice develop less emphysema and have fewer CD11b(+)CD11c(+) mDCs infiltrating the lungs as compared with wild-type mice. Proteolytic cleavage of C3 by neutrophil elastase releases C3a, which in turn increases the expression of its receptor (C3aR) on lung mDCs. Mice deficient in the C3aR (C3ar(-/-)) partially phenocopy the attenuated responses to chronic smoke observed in C3(-/-) mice. Consistent with a role for C3 in emphysema, C3 and its active fragments are deposited on the lung tissue of smokers with emphysema, and smoke-exposed mice. Together, these findings suggest a critical role for C3a through autocrine/paracrine induction of C3aR in the pathogenesis of cigarette smoke-induced sterile inflammation and provide new therapeutic targets for the treatment of emphysema.
Project description:Chronic rhinosinusitis with nasal polyps (CRSwNP) is an inflammatory disease with an unknown etiology. Recent studies have implicated the complement system as a potential modulator of disease immunopathology. We performed proteomic pathway enrichment analysis of differentially increased proteins, and found an enrichment of complement cascade pathways in the nasal mucus of individuals with CRSwNP as compared to control subjects. Sinonasal mucus levels of complement 3 (C3) correlated with worse subjective disease severity, whereas no significant difference in systemic C3 levels could be determined in plasma samples. Given that human sinonasal epithelial cells were the predominate sinonasal source of C3 and complement anaphylatoxin 3a (C3a) staining, we focused on their role in in vitro studies. Baseline intracellular C3 levels were higher in CRSwNP cells, and following exposure to Aspergillus fumigatus (Af) extract, they released significantly more C3 and C3a. Inhibition of complement 3a receptor (C3aR) signaling led to a decrease in Af-induced C3 and C3a release, both in vitro and in vivo. Finally, we found in vivo that C3aR deficiency or inhibition significantly reduced inflammation and CRS development in a mouse model of Af-induced CRS. These findings demonstrate that local sinonasal complement activation correlates with subjective disease severity, and that local C3aR antagonism significantly ameliorates Af-induced CRS in a rodent model.
Project description:Complement synthesis in cells of origin is strongly linked to the pathogenesis and progression of renal disease. Multiple studies have examined local C3 synthesis in renal disease and elucidated the contribution of local cellular sources, but the contribution of infiltrating inflammatory cells remains unclear. We investigate the relationships among C3, macrophages and Th17 cells, which are involved in interstitial fibrosis. Here, we report that increased local C3 expression, mainly by monocyte/macrophages, was detected in renal biopsy specimens and was correlated with the severity of renal fibrosis (RF) and indexes of renal function. In mouse models of UUO (unilateral ureteral obstruction), we found that local C3 was constitutively expressed throughout the kidney in the interstitium, from which it was released by F4/80+macrophages. After the depletion of macrophages using clodronate, mice lacking macrophages exhibited reductions in C3 expression and renal tubulointerstitial fibrosis. Blocking C3 expression with a C3 and C3aR inhibitor provided similar protection against renal tubulointerstitial fibrosis. These protective effects were associated with reduced pro-inflammatory cytokines, renal recruitment of inflammatory cells, and the Th17 response. in vitro, recombinant C3a significantly enhanced T cell proliferation and IL-17A expression, which was mediated through phosphorylation of ERK, STAT3, and STAT5 and activation of NF-kB in T cells. More importantly, blockade of C3a by a C3aR inhibitor drastically suppressed IL-17A expression in C3a-stimulated T cells. We propose that local C3 secretion by macrophages leads to IL-17A-mediated inflammatory cell infiltration into the kidney, which further drives fibrogenic responses. Our findings suggest that inhibition of the C3a/C3aR pathway is a novel therapeutic approach for obstructive nephropathy.
Project description:This SuperSeries is composed of the following subset Series: GSE29409: Subcutaneous and omental white adipose tissue biopsies analysed from five obese patients GSE29410: Subcutaneous and omental white adipose tissue biopsies analysed from three obese patients Refer to individual Series
Project description:Obesity is a strong risk factor for resistance to insulin-mediated glucose disposal, a precursor of type 2 diabetes and other disorders. However, not all obese individuals are insulin resistant. We sought to identify the molecular pathways that might cause obesity-associated insulin resistance in humans by studying the morbidly obese who were insulin sensitive versus insulin resistant, thereby eliminating obesity as a variable.Combining gene expression profiling with computational approaches, we determined the global gene expression signatures of omental and subcutaneous adipose tissue samples obtained from similarly obese patients undergoing gastric bypass surgery.Gene sets related to chemokine activity and chemokine receptor binding were identified as most highly expressed in the omental tissue from insulin-resistant compared with insulin-sensitive subjects, independent of the body mass index. These upregulated genes included chemokines (C-C motif) ligand 2, 3, 4, and 18 and interleukin-8/(CC-X motif) ligand 8 and were not differentially expressed in the subcutaneous adipose tissues between the 2 groups of subjects. Insulin resistance, but not the body mass index, was associated with increased macrophage infiltration in the omental adipose tissue, as was adipocyte size, in these morbidly obese subjects.Our findings have demonstrated that inflammation of the omental adipose tissue is strongly associated with insulin resistance in human obesity even in subjects with similar body mass index values.
Project description:Subcutaneous adipose tissue and visceral adipose tissue samples were obtained from severely obese individuals that underwent bariatric surgery. The goal of this study was to compare genome-wide gene expression levels in the two tissue types from healthy and unhealthy severely obese individuals. Whole-transcriptome subcutaneous adipose tissue gene expression levels were determined in 73 individuals with a BMI >35 kg/m2. Whole-transcriptome visceral adipose tissue gene expression levels were determined in 69 individuals with a BMI >35 kg/m2. Modules of co-expressed genes likely to be functionally related were identfied and correlated with BMI, plasma levels of glucose, insulin, HbA1c, triglycerides, non-esterified fatty acids, ALAT, ASAT, C-reactive protein, and LDL- and HDL cholesterol. Overall design: Gene expression data was determined for untreated whole subcutaneous adipose tissue (n=73) from unrelated Dutch severely obese individuals. Gene expression data was determined for untreated whole visceral adipose tissue (n=69) from unrelated Dutch severely obese individuals.
Project description:Single nucleotide polymorphisms (SNPs) rs7903146 and rs12255372 located within TCF7L2 gene have been identified as the strongest common genetic risk factors for development of type 2 diabetes (T2D). We hypothesized that these genetic variants might increase the risk of T2D through regulation of alternative splicing or expression level of TCF7L2 in human adipose tissue.Expression of 13 assays detecting alternatively spliced forms of TCF7L2 was measured by quantitative reverse-transcriptase PCR (qRT-PCR) in paired biopsies of omental and subcutaneous adipose tissue from 159 obese individuals (BMI 54.6+/-12.2 kg/m(2)). TCF7L2 expression in both types of adipose tissue was not associated with SNPs rs7903146 and rs12255372, T2D status and blood levels of glucose or glycosylated hemoglobin (HbA1c). Expression of assays "ex12-13", "ex12-14" and "ex13-13a" detecting C-terminal alternative exons of TCF7L2 was higher in subcutaneous compared to omental adipose tissue by 1.46 fold (p = 6.5x10(-15)), 1.41 fold (p = 1.4x10(-9)) and 1.26 fold (p = 4.7x10(-6)) in the control group and by 1.86 fold (p = 1.7x10(-4)), 1.77 fold (p = 7.3x10(-4)) and 1.58 fold (p = 6.1x10(-4)) in the T2D group. A pathway enrichment analysis on transcripts significantly co-expressed with TCF7L2 in a microarray set combined with individual expression assays, suggested tissue-specific roles of TCF7L2 splicing forms in regulation of transcription, signal transduction and cell adhesion.Expression of TCF7L2 alternatively spliced forms may have different functional roles in omental and subcutaneous adipose tissue but is not associated with SNPs rs7903146 and rs12255372 or T2D status.