Background and aims Crohn’s disease (CD) is associated with complex microbe-host interactions, involving changes in microbial communities, and gut barrier defects, leading to the translocation of microorganisms to surrounding adipose tissue (AT). We evaluated the presence of beige AT depots in CD and questioned whether succinate and/or bacterial translocation promotes white-to-beige transition in adipocytes. Methods Visceral (VAT) and subcutaneous (SAT) AT biopsies, serum and plasma were obtained from patients with active (n=21) or inactive (n=12) CD, and from healthy controls (n=15). Adipose-derived stem cells (ASCs) and AT macrophages (ATMs) were isolated from VAT biopsies. Results Plasma succinate levels were significantly higher in patients with active CD than in controls and were intermediate in those with inactive disease. Plasma succinate correlated with the inflammatory marker high-sensitivity C-reative protein. Expression of the succinate receptor SUCNR1 was higher in VAT, ASCs and ATMs from the active CD group than from the inactive or control groups. Succinate treatment of ASCs elevated the expression of several beige AT markers from controls and from patients with inactive disease, including uncoupling protein-1 (UCP1). Notably, beige AT markers were prominent in ASCs from patients with active CD. Secretome profiling revealed that ASCs from patients with active disease secrete beige AT-related proteins, and co-culture assays showed that bacteria also trigger the white-to-beige switch of ASCs from patients with CD. Finally, AT depots from patients with CD exhibited a conversion from white to beige AT together with high UCP1 expression, which was corroborated by in situ thermal imaging analysis. Conclusions Succinate and bacteria trigger white-to-beige AT transition in CD. Understanding the role of beige AT in CD might aid in the development of therapeutic or diagnostic interventions.
Anti-TNF biologics have been shown to markedly improve the quality of life for patients with Crohn’s disease (CD), yet one-third of patients fail to benefit from this treatment. Patients with CD develop a characteristic wrapping of visceral adipose tissue (VAT) in the inflamed intestinal area, termed creeping fat, and it is known that adipose tissue expansion influences the efficacy of anti-TNF drugs. We questioned whether anti-TNF therapies impact the creeping fat in CD, which might affect the outcome of the disease. Adipose tissue biopsies were obtained from a cohort of 14 patients with CD that received anti-TNF drugs and from 29 non-anti-TNF-treated patients (control group) matched by sex, age, and body mass index undergoing surgical interventions for symptomatic complications. We found that anti-TNF therapies restored adipose tissue morphology and suppressed immune cell infiltration in the creeping fat. Additionally, anti-TNF treatments appeared to markedly improve the pro-inflammatory phenotype of adipose-tissue macrophages and adipose-tissue-derived stem cells. Our study provides evidence that anti-TNF medications influence immune cells and progenitor cells in the creeping of patients with CD, suppressing inflammation. We propose that perilesional VAT should be considered when administering anti-TNF therapy in patients with CD.
Patients with Crohn’s disease (CD) who smoke are known to have a worse prognosis than never-smokers and a higher risk for post-surgical recurrence, whereas patients who quit smoking after surgery have significantly lower post-operative recurrence. The hypothesis was that smoking induces epigenetic changes that impair the capacity of adipose stem cells (ASCs) to suppress the immune system. It was also questioned whether this impairment remains in ex-smokers with CD. ASCs were isolated from non-smokers, smokers and ex-smokers with CD and their interactions with immune cells were studied. The ASCs from both smokers and ex-smokers promoted macrophage polarization to an M1 pro-inflammatory phenotype, were not able to inhibit T- and B-cell proliferation in vitro and enhanced the gene and protein expression of inflammatory markers including interleukin-1b. Genome-wide epigenetic analysis using two different bioinformatic approaches revealed significant changes in the methylation patterns of genes that are critical for wound healing, immune and metabolic response and p53-mediated DNA damage response in ASCs from smokers and ex-smokers with CD. In conclusion, cigarette smoking induces a pro-inflammatory epigenetic signature in ASCs that likely compromises their therapeutic potential.
Background Crohn’s disease (CD) is characterized by persistent inflammation and ulcerations at the small or large bowel, provoking chronic low-grade systemic inflammation. Adipose tissue (AT) is believed to play an active role in the pathogenesis of CD, as the expansion of mesenteric fat attached to the inflamed segments of the intestine, also known as “creeping fat,” is a hallmark of the disease that seems to be directly related to disease activity. We demonstrated that adipose-stem cells (ASC) isolated from the creeping fat of CD patients showed a proinflammatory phenotype and increased the proliferation, migration, and phagocytic capacities of these cells. Taking into account the widely described effects of TNFalpha on the biology and functionality of adipocytes, we believe that biological therapies based on anti-TNF agents modify the inflammatory status of creeping fat. In this context, the effect of anti-TNF treatment on mesenteric fat is poorly studied, and the results are divergent. Methods Creeping fat biopsies were obtained from active CD patients that underwent surgery for symptomatic complications: 10 patients were on anti-TNF therapy (at least 6-months prior to surgery) and 10 patients never received any biological therapy. The groups were comparable in age, sex, and body mass index. We isolated from AT biopsies: AT explants, ASC, and adipose tissue macrophages (ATM). Adipose tissue was fixed in 10% phosphate-buffered formalin and embedded in paraffin for histological studies. The proliferation of ASC was performed using the CellTraceTM Violet Cell proliferation kit using flow cytometry and the cell migration of ASC was analyzed using a Tranwell system (8 mmpore polycarbonate membrane). Results Histological studies revealed that AT of patients treated with anti-TNF therapy recovered adipocytes morphology and showed lower infiltration of immune cells. Interestingly, we found a significant decrease in the gene expression of pro-inflammatory cytokines (IL1B, IL6, TNFA) in the creeping fat of CD patients treated with anti-TNF (Figure 1A). Furthermore, ATMs isolated from patients treated with anti-TNF showed a significant decrease in the gene expression of antigen-presenting markers (CD74, CIITa, HLA-DPB and HLA-DM) (Figure 1B). To note, ASC isolated from patients with anti-TNF therapy has significantly decreased their proliferation and migration capacities as well as the pro-inflammatory gene expression. Moreover, the anti-inflammatory gene expression and secretion were significantly increased in these cells (Figure 1C). Conclusion Anti-TNF therapies impact on the creeping fat of CD patients improving the phenotype of this tissue and this may cause a beneficial effect on CD.
Background Crohn’s disease (CD) is characterized by severe transmural inflammation with subsequent destruction of the intestinal barrier. Bacterial infiltration across this leaky gut facilitates access to the mesenteric fat and the development of a subsequent inflammatory reaction in the surrounding adipose tissue named creeping fat (CF). Dysbiosis in CD patients has been associated with an increase in succinate-producing bacteria and a decrease in succinate-consuming bacteria. In fact, elevated succinate levels have been found in the intestine and feces of CD patients. Furthermore, succinate is an inductor of beige adipogenesis in white adipose tissue progenitors. Methods Visceral and subcutaneous adipose tissue biopsies (VAT and SAT), serum, and plasma were obtained from a cohort of active CD (n=20), inactive CD (n=12), and control group (n=15). From adipose tissue biopsies, adipose-derived stem cells (ASCs) and adipose tissue macrophages (ATMs) were isolated. Different experiments were performed such as protein uncoupling protein 1 (UCP1)-immunohistochemistry and immunofluorescence, gene expression studies, adipose tissue explants, proteomic analysis of ASCs, succinate determinations, bio-impedancemetry, and infrared photographs. Results Succinate treatment increased markers of beige adipose tissue in ASCs from controls and inactive CD patients (Fig. A). Surprisingly, the markers of beige adipose tissue were already high in ASCs isolated from active CD, due to being exposed to an environment with high levels of succinate in vivo. Proteomic analysis of isolated CD-ASCs revealed that these cells secrete beige adipose tissue-related proteins compared to Control-ASCs (Fig. B). Furthermore, bacterial translocation increases the conversion of pre-adipocytes from white to beige adipose tissue in CD individuals (Fig. C). Immunohistochemical study of UCP-1, confirms increased staining in adipose samples from CD patients from both depots (SAT and VAT) (Fig. D). Altogether, adipose tissue depots from CD patients had a conversion from white to beige adipose tissue with a high protein UCP1-gene expression. Thermic images show an increase of temperature in the intestinal area of active CD patients that is not observed in inactive CD patients or the control group. Conclusion Understanding the role of beige adipose tissue in CD could help develop new therapeutic or diagnostic strategies in these patients.
Background Crohn’s disease (CD) is characterized by the expansion of mesenteric fat attached to the inflamed segments of the intestine, also known as “creeping fat” which seems to be directly related to disease activity. Our group revealed that adipose-stem cells (hASCs) isolated from the creeping fat of CD subjects are dysfunctional (showing a high inflammatory profile, high invasive and phagocytic capacities, and worse immunosuppressive properties); and this dysfunction is maintained even in hASCs isolated from CD subjects in remission of the disease.1 Methods 1) Culture and characterization of hASCs isolated from adipose tissue biopsies of active CD, inactive CD, and healthy subjects (n=25). Visceral origin: creeping fat in active CD subjects and mesenteric fat in CD subjects in remission and healthy subjects. 2) Comparative DNA methylome analysis in hASCs isolated from the included population (Infinium Human-Methylation EPIC (850K) BeadChip; Illumina, Inc). 3) Transcriptomic study in hASCs isolated from the included population (Illumina HiSeq 2500 system). 4) Bioinformatic analysis & data integration. Results Methylation and transcriptomic studies revealed a multi-omic profile of hASCs isolated from CD subjects compared to control individuals (Heatmaps Fig 1A). Indeed, the integration of genome-wide methylation changes and gene expression differences revealed the main candidate’s genes (Figure 1B). The most significant upregulated gene in CD was Mab-21 like 2 (MAB21L2) (Fig 1B-C). This gene encodes a downstream target of transforming growth factor-beta signaling. MAB21L2 was validated in an independent cohort of hASC isolated from control, active, and inactive CD subjects (n=7/each group) using qPCR. In agreement, MAB21L2 gene expression was significantly higher in hASCs isolated from the active and inactive group than in the control group (Fig 1D). Another interesting candidate gene found was tyrosine kinase 2 (TYK2) which is significantly upregulated in active CD subjects. This gene promulgates cytokine signals by phosphorylating receptor subunits. It is also a component of both the type I and III interferon signaling pathways.2 Finally, another gene upregulated in remission of the disease is the calcium voltage-gated channel subunit alpha 1H (CACNA1H), which has been involved in low-grade inflammation and has been proposed as an important player in IBD during the remission phase.3 Conclusion Integration of data revealed genes involved in the dysregulation of hASCs associated with CD and genes related to disease remission. Reference 1. Serena C Stem Cell Rep 2017 9(4):1109–23; 2De Vries LCS JCC 2021 617-30; 3Picard E Br J Pharmacol 2019;176:950–63
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