Serum levels and mesenteric fat tissue expression of adiponectin and leptin in patients with Crohn's disease

Prevalence of metabolic syndrome in patients with inflammatory bowel disease: a systematic review and meta-analysis

OBJECTIVES

Patients with inflammatory bowel disease (IBD) may experience comorbidities involving metabolic syndrome (MetS). However, this association remains controversial. Our objective was to estimate the prevalence of MetS in patients with IBD and assess whether MetS is more strongly associated with ulcerative colitis (UC) or Crohn's disease (CD).

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

PubMed, Cochrane Library, Web of Science, EMBASE and MEDLINE were searched from their inception to July 2022.

ELIGIBILITY CRITERIA

Observational studies reporting data regarding the rate of comorbid MetS among patients with IBD and published in English.

DATA EXTRACTION AND SYNTHESIS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses and the Meta-analysis of Observational Studies in Epidemiology reporting guidelines were followed. Pooled prevalence, ORs and 95% CIs were calculated using random-effects models. The Newcastle-Ottawa Scale and the Agency for Healthcare Research and Quality checklist were used. Heterogeneity, sensitivity and stratified analyses were performed using R (V.4.2.1).

RESULTS

11 eligible studies involving 2501 patients were included. Of these studies, four reported MetS prevalence separately by IBD phenotype, and only one contained a non-IBD comparison group. Overall, the methodological quality of the included studies was moderate. The pooled prevalence of MetS in IBD was 19.4% (95% CI 15.1% to 23.8%), with a moderate heterogeneity (I2=51.8%, Cochrane Q statistic=12.4, p=0.053). Stratified analyses demonstrated that the aggregate estimate of comorbid MetS was significantly higher in UC than in CD (38.2% vs 13.6%, χ2=4.88, p=0.03). We found a positive association between MetS and UC compared with CD (OR=2.11, 95% CI 1.19 to 3.74, p=0.01). Additionally, four studies identified that higher age was a risk factor associated with the development of MetS.

CONCLUSIONS

MetS is not rare in IBD, especially in UC. However, longitudinal studies are needed to further clarify the relationship between IBD and MetS.

PROSPERO REGISTRATION NUMBER

CRD42022346340.

Creeping Fat in the Pathogenesis of Crohn's Disease: An Orchestrator or a Silent Bystander?

Although the phenomenon of hypertrophied adipose tissue surrounding inflamed bowel segments in Crohn's disease has been described since 1932, the mechanisms mediating the creeping fat formation and its role in the pathogenesis of the disease have not been fully unraveled. Recent advances demonstrating the multiple actions of adipose tissue beyond energy storage have brought creeping fat to the forefront of scientific research. In Crohn's disease, dysbiosis and transmural injury compromise the integrity of the intestinal barrier, resulting in an excessive influx of intraluminal microbiota and xenobiotics. The gut and peri-intestinal fat are in close anatomic relationship, implying a direct reciprocal immunologic relationship, whereas adipocytes are equipped with an arsenal of innate immunity sensors that respond to invading stimuli. As a result, adipocytes and their progenitor cells undergo profound immunophenotypic changes, leading to adipose tissue remodeling and eventual formation of creeping fat. Indeed, creeping fat is an immunologically active organ that synthesizes various pro- and anti-inflammatory cytokines, profibrotic mediators, and adipokines that serve as paracrine/autocrine signals and regulate immune responses. Therefore, creeping fat appears to be involved in inflammatory signaling, which explains why it has been associated with a higher severity or complicated phenotype of Crohn's disease. Interestingly, there is growing evidence for an alternative immunomodulatory function of creeping fat as a second barrier that prevents an abnormal systemic inflammatory response at the expense of an increasingly proliferating profibrotic environment. Further studies are needed to clarify how this modified adipose tissue exerts its antithetic effect during the course of Crohn's disease.

Adiponectin Levels in Inflammatory Bowel Disease: A Systematic Review and Meta-Analysis

INTRODUCTION

Adipose tissue plays an important role in the pathogenesis of inflammatory conditions. The role of adipokines in inflammatory bowel disease (IBD) has been evaluated in the current literature with conflicting results. The aim of this study was to evaluate adiponectin levels in IBD patients, including Crohn's disease (CD) and ulcerative colitis (UC), compared to controls, as well as further subgroup analyses. Hence, assessing the potential role of adiponectin as a surrogate marker.

METHODS

We performed a systematic electronic search on PubMed, Embase, Scopus, and Cochrane Library, including observational or interventional studies evaluating serum or plasma adiponectin levels in IBD patients in humans. The primary summary outcome was the mean difference (MD) in serum or plasma adiponectin levels between IBD patients versus controls. Subgroup analyses were conducted involving adiponectin levels in CD and UC compared to controls, as well as CD compared to UC.

RESULTS

A total of 20 studies were included in our qualitative synthesis and 14 studies in our quantitative synthesis, with a total population sample of 2,085 subjects. No significant MD in serum adiponectin levels was observed between IBD patients versus controls {-1.331 (95% confidence interval [CI]: -3.135-0.472)}, UC patients versus controls (-0.213 [95% CI: -1.898-1.472]), and CD patients versus controls (-0.851 [95% CI: -2.263-0.561]). Nevertheless, a significant MD was found between UC patients versus CD patients (0.859 [95% CI: 0.097-1.622]).

CONCLUSIONS

Serum adiponectin levels were not able to differentiate between IBD, UC, and CD patients compared to controls. However, significantly higher serum adiponectin levels were observed in UC compared to CD patients.

Circulating Levels of WISP-1 (Wnt1-Inducible Signaling Pathway Protein 1) and Other Selected Adipokines in Children With Inflammatory Bowel Disease

Wnt1 inducible protein-1 signaling pathway (WISP-1) is a relatively new adipokine involved in many cellular processes, including epithelial mucosa healing. The aim of the study was to compare circulating levels of WISP-1 and other selected adipokines [adiponectin, resistin and retinol-binding protein 4 (RBP-4)] in children with inflammatory bowel disease (IBD) with healthy controls and to investigate possible differences between Crohn's disease patients. (CD) or ulcerative colitis (UC). The study was performed as a case-control study. In addition to adipokines, anthropometric, lipid parameters, markers of inflammation or disease activity were evaluated in all participants. Compared to healthy controls (n=20), significantly lower levels of adiponectin and higher levels of resistin and WISP-1 were found in patients with IBD (n=58). Elevation of WISP-1 was detected only in the CD group (n=31). There were no differences in RBP-4 levels between the groups. Adiponectin, WISP-1 and RBP-4 were independently associated with body mass index only, resistin levels were associated with C-reactive protein levels and leukocyte counts. Adverse adipokines production reflects presence of dysfunctional fat tissue in IBD patients. Higher levels of WISP-1 in CD compared to patients with UC may indicate a specific role for mesenteric adipose tissue in WISP-1 production.

The Complex Relationship Between Microbiota, Immune Response and Creeping Fat in Crohn's Disease

In the last decade, there has been growing interest in the pathological involvement of hypertrophic mesenteric fat attached to the serosa of the inflamed intestinal segments involved in Crohn's disease [CD], known as creeping fat. In spite of its protective nature, creeping fat harbours an aberrant inflammatory activity which, in an already inflamed intestine, may explain why creeping fat is associated with a greater severity of CD. The transmural inflammation of CD facilitates the interaction of mesenteric fat with translocated intestinal microorganisms, contributing to activation of the immune response. This may be not the only way in which microorganisms alter the homeostasis of this fatty tissue: intestinal dysbiosis may also impair xenobiotic metabolism. All these CD-related alterations have a functional impact on nuclear receptors such as the farnesoid X receptor or the peroxisome proliferator-activated receptor γ, which are implicated in regulation of the immune response, adipogenesis and the maintenance of barrier function, as well as on creeping fat production of inflammatory-associated cells such as adipokines. The dysfunction of creeping fat worsens the inflammatory course of CD and may favour intestinal fibrosis and fistulizing complications. However, our current knowledge of the pathophysiology and pathogenic role of creeping fat is controversial and a better understanding might provide new therapeutic targets for CD. Here we aim to review and update the key cellular and molecular alterations involved in this inflammatory process that link the pathological components of CD with the development of creeping fat.

Molecular and Pathophysiological Links between Metabolic Disorders and Inflammatory Bowel Diseases

Despite considerable epidemiological evidence indicating comorbidity between metabolic disorders, such as obesity, type 2 diabetes, and non-alcoholic fatty liver disease, and inflammatory bowel diseases (IBD), such as Crohn’s disease and ulcerative colitis, as well as common pathophysiological features shared by these two categories of diseases, the relationship between their pathogenesis at molecular levels are not well described. Intestinal barrier dysfunction is a characteristic pathological feature of IBD, which also plays causal roles in the pathogenesis of chronic inflammatory metabolic disorders. Increased intestinal permeability is associated with a pro-inflammatory response of the intestinal immune system, possibly leading to the development of both diseases. In addition, dysregulated interactions between the gut microbiota and the host immunity have been found to contribute to immune-mediated disorders including the two diseases. In connection with disrupted gut microbial composition, alterations in gut microbiota-derived metabolites have also been shown to be closely related to the pathogeneses of both diseases. Focusing on these prominent pathophysiological features observed in both metabolic disorders and IBD, this review highlights and summarizes the molecular risk factors that may link between the pathogeneses of the two diseases, which is aimed at providing a comprehensive understanding of molecular mechanisms underlying their comorbidity.

The role of chemokines and adipokines as biomarkers of Crohn's disease activity: a systematic review of the literature

INTRODUCTION

Crohn's disease (CD) is an inflammatory bowel disease (IBD) that affects the gastrointestinal tract and can have a major impact on the patient's quality of life and social/professional activities. Asymptomatic patients, or those with mild symptoms, experience the active disease with subclinical manifestation. Systematic review (SR) was performed to look for evidence for the role of chemokines and adipokines as markers for CD activity.

METHODS

This SR was conducted by searching published studies in international and regional databases up till July, 2020. CD patients were adults with the disease in activity or remission. All adipokines and chemokines were considered for the analysis and the Rayyan QCRI system was used.

RESULTS

In total, 20 studies were included. Six addressed chemokines and eight adipokines as potential biomarkers of CD activity. CXCL8 was the most studied chemokine (8 studies) and the results were controversial, with 62.5% showing a significant association with CD activity. CXCL10 was investigated by 4 studies and 50% identified it as a potential biomarker. CCL2, CCL11, CCL26 and CXCL1 were examined by 2 articles each. CXCL8 (P=0.002/P=0.001) and CXCL1 (P<0.001) presented the lowest? P value, which qualifies them as potential markers of disease activity. All the adipokines were tested in peripheral blood but 44.4% were also tested in intestinal mucosa, while the percentage in the chemokines' studies was 76.9% in peripheral blood, 46.1% in intestinal mucosa and 7.6% in urine sample respectively.

CONCLUSION

The development of disease activity biomarkers for CD is becoming relevant for clinical practice. Chemokines and adipokines have the potential to signalize CD activity, but validation in larger cohorts of patients, preferable multicenter studies are still needed.

Role of Adipose Tissue in Inflammatory Bowel Disease

Inflammatory bowel diseases (IBDs), chronic inflammatory disorders affecting the gastrointestinal tract, include Crohn's disease and ulcerative colitis. There are increasing clinical and experimental data showing that obesity, especially visceral adiposity, plays a substantial role in the pathogenesis of IBD. Obesity seems to be an important risk factor also for IBD disease severity and clinical outcomes. Visceral adipose tissue is an active multifunctional metabolic organ involved in lipid storage and immunological and endocrine activity. Bowel inflammation penetrates the surrounding adipose tissue along the mesentery. Mesenteric fat serves as a barrier to inflammation and controls immune responses to the translocation of gut bacteria. At the same time, mesenteric adipose tissue may be the principal source of cytokines and adipokines responsible for inflammatory processes associated with IBD. This review is particularly focusing on the potential role of adipokines in IBD pathogenesis and their possible use as promising therapeutic targets.

Intestinal Alkaline Phosphatase Combined with Voluntary Physical Activity Alleviates Experimental Colitis in Obese Mice. Involvement of Oxidative Stress, Myokines, Adipokines and Proinflammatory Biomarkers

Intestinal alkaline phosphatase (IAP) is an essential mucosal defense factor involved in the process of maintenance of gut homeostasis. We determined the effect of moderate exercise (voluntary wheel running) with or without treatment with IAP on the course of experimental murine 2,4,6-trinitrobenzenesulfonic acid (TNBS) colitis by assessing disease activity index (DAI), colonic blood flow (CBF), plasma myokine irisin levels and the colonic and adipose tissue expression of proinflammatory cytokines, markers of oxidative stress (SOD2, GPx) and adipokines in mice fed a standard diet (SD) or high-fat diet (HFD). Macroscopic and microscopic colitis in sedentary SD mice was accompanied by a significant decrease in CBF, and a significant increase in the colonic expression of tumor necrosis factor-alpha (TNF-α), IL-6, IL-1β and leptin mRNAs and decrease in the mRNA expression of adiponectin. These effects were aggravated in sedentary HFD mice but reduced in exercising animals, potentiated by concomitant treatment with IAP, especially in obese mice. Exercising HFD mice demonstrated a substantial increase in the mRNA for adiponectin and a decrease in mRNA leptin expression in intestinal mucosa and mesenteric fat as compared to sedentary animals. The expression of SOD2 and GPx mRNAs was significantly decreased in adipose tissue in HFD mice, but these effects were reversed in exercising mice with IAP administration. Our study shows for the first time that the combination of voluntary exercise and oral IAP treatment synergistically favored healing of intestinal inflammation, strengthened the antioxidant defense and ameliorated the course of experimental colitis; thus, IAP may represent a novel adjuvant therapy to alleviate inflammatory bowel disease (IBD) in humans.

Circulating Leptin Levels as a Potential Biomarker in Inflammatory Bowel Diseases: A Systematic Review and Meta-Analysis

BACKGROUND

The differential diagnosis of inflammatory bowel diseases (IBDs) between Crohn's disease (CD) and ulcerative colitis (UC) is important for designing an effective therapeutic regimen. However, without any adequate gold standard method for differential diagnosis currently, therapeutic design remains a major challenge in clinical practice. In this context, recent studies have showed that circulating leptin stands out as a potential biomarker for the categorization of IBDs. Thus, we aimed to summarize the current understanding of the prognostic and diagnostic value of serum leptin in patients with IBDs.

METHODS

A systematic search was performed in PubMed/MEDLINE, Scopus, Cochrane Library, and Web of Science databases. Articles that aimed to study the relationship between circulating levels of leptin and IBDs were included. Finally, the meta-analysis was performed with the mean serum leptin levels in patients with IBDs and healthy controls using RevMan 5.3 software, with I2 > 50% as a criterion for substantial heterogeneity.

RESULTS

Nineteen studies were included. Serum leptin levels among patients with IBDs and healthy controls did not show a significant difference (95% CI, -2.15 to 0.57; I2, 86%, P ≤ 0.00001). Similarly, there was no association of leptin levels with the activity of IBDs (95% CI, -0.24 to 0.06; I2, 50%; P = 0.13). However, serum leptin levels were significantly higher in patients with CD than those in patients with UC (95% CI, -2.09 to -0.37; I2, 7%; P ≤ 0.36).

CONCLUSION

This review suggested that serum leptin levels might be a promising biomarker to help in the differentiation between CD and UC.

Intestinal Macrophages at the Crossroad between Diet, Inflammation, and Cancer

Intestinal macrophages are key players in the regulation of the oral tolerance, controlling gut homeostasis by discriminating innocuous antigens from harmful pathogens. Diet exerts a significant impact on human health, influencing the composition of gut microbiota and the developing of several non-communicable diseases, including cancer. Nutrients and microbiota are able to modify the profile of intestinal macrophages, shaping their key function in the maintenance of the gut homeostasis. Intestinal disease often occurs as a breakdown of this balance: defects in monocyte-macrophage differentiation, wrong dietary habits, alteration of microbiota composition, and impairment in the resolution of inflammation may contribute to the development of intestinal chronic inflammation and colorectal cancer. Accordingly, dietary interventions and macrophage-targeted therapies are emerging as innovative tools for the treatment of several intestinal pathologies. In this review, we will describe the delicate balance between diet, microbiota and intestinal macrophages in homeostasis and how the perturbation of this equilibrium may lead to the occurrence of inflammatory conditions in the gut. The understanding of the molecular pathways and dietary factors regulating the activity of intestinal macrophages might result in the identification of innovative targets for the treatments of intestinal pathologies.

Crohn's disease associated adenocarcinoma of ileocaecal region: a miscalculated approach

Adenocarcinoma of the bowel is a dreadful sequelae of inflammatory bowel disease that can be difficult to diagnose and has been shown to have poor prognosis. The diagnosis is often made on histopathological examination of the resected specimen for what is suspected to be an exacerbation of the underlying intestinal Crohn's. A 39-year-old woman who was being treated for small bowel Crohn's disease for 4 years presented with features of intermittent intestinal obstruction that was refractory to medical therapy. A contrast CT of the abdomen was suggestive of ileocaecal Crohn's disease, and colonoscopy revealed a stricture at proximal transverse colon with multiple superficial ulcers. She underwent a mesentery sparing right hemicolectomy and had an uneventful recovery. The biopsy, however, was reported to be moderately differentiated adenocarcinoma stage T3N0 with a harvest of four pericolic nodes. Adjuvant chemotherapy was advised, which she deferred. Ten months later, she presented to the emergency room with features of intestinal obstruction. Contrast CT of the abdomen showed thickening at the anastomotic site with intestinal obstruction. On exploratory laparotomy, tumour recurrence was noted at the site of the anastomosis and diffuse peritoneal metastasis. A palliative diversion ileostomy was done due to inoperable obstructing disease. She was then given palliative therapy and subsequently succumbed to the illness. The inclusion of mesentery with the resected specimen in Crohn's disease has been a debate over many years. Since the preoperative diagnosis of carcinoma of the bowel in Crohn's disease is challenging, all ileocolic resections should be radical as done in oncological resections. This would yield better oncological safety and may improve survival rates.

Whole transcriptional analysis identifies markers of B, T and plasma cell signaling pathways in the mesenteric adipose tissue associated with Crohn's disease

Background

Crohn’s disease (CD) is a multifactorial disease characterized by chronic intestinal inflammation. The increased visceral adiposity near the affected intestinal area, of which mesenteric adipose tissue (MAT) is the main component, is a feature of CD. Both protective and pathological roles have been attributed to this disease-associated tissue in CD. To understand the contribution of MAT to CD pathophysiology, a molecular and cellular signature of disease-associated MAT in CD patients was provided.

Methods

We performed an observational study with whole transcriptional analysis by RNA sequencing (RNA-seq) of MAT and ileal mucosa from CD patients with active disease and controls. qPCR and immunohistology were performed for validation analysis.

Results

RNA-seq identified 17 significantly regulated genes (|FC| > 1.5; FDR < 0.05) in CD-MAT compared to non-IBD controls, with a marked upregulation of plasma cell genes (i.e., IGLL5, MZB1, CD79A, POU2AF1, FCRL5, JCHAIN, DERL3, SDC1, PIM2). A less strict statistical cutoff value (|FC| > 1.5, nominal p ≤ 0.05) yielded a larger list of 651 genes in CD-MAT compared to controls. CD ileum showed the significant regulation compared to control ileum of 849 genes (|FC| > 1.5; FDR < 0.05) or 2654 genes (|FC| > 1.5, nominal p ≤ 0.05). Ingenuity Pathway Analysis revealed the significant regulation of pathways related to T- and B cell functionality in the MAT of CD patients. Despite the differences between the MAT and ileal signatures of CD patients, we identified a subset of 204 genes significantly modulated in both tissues compared to controls. This common signature included genes related to the plasma cell signature. Genes such as S100A8, S100A9 (calprotectin) and IL1B, which are associated with acute inflammatory response, were exclusively regulated in the ileal mucosa of CD disease. In contrast, some genes encoding for lymphocyte receptors such as MS4A1, CD3D and CD79A were exclusively regulated in CD-MAT, exhibiting a different pattern of immune cell activation compared to the ileal mucosa in CD patients. qPCR and immunohistology confirmed the presence of large infiltrates of CD3⁺ CD20⁺ lymphocytes and CD138⁺ plasma cells in CD-MAT.

Conclusion

Our data strongly supports the role of CD-associated MAT as a site for T-, B- and plasma cell activation, and suggests that it could also act as a reservoir of memory immune responses.

Role of Obesity, Mesenteric Adipose Tissue, and Adipokines in Inflammatory Bowel Diseases.Biomolecules. 2019;9. [PMID: 31779136 DOI: 10.3390/biom9120780]

Inflammatory bowel diseases (IBDs) are a group of disorders which include ulcerative colitis and Crohn's disease. Obesity is becoming increasingly more common among patients with inflammatory bowel disease and plays a role in the development and course of the disease. This is especially true in the case of Crohn's disease. The recent results indicate a special role of visceral adipose tissue and particularly mesenteric adipose tissue, also known as "creeping fat", in pathomechanism, leading to intestinal inflammation. The involvement of altered adipocyte function and the deregulated production of adipokines, such as leptin and adiponectin, has been suggested in pathogenesis of IBD. In this review, we discuss the epidemiology and pathophysiology of obesity in IBD, the influence of a Western diet on the course of Crohn's disease and colitis in IBD patients and animal's models, and the potential role of adipokines in these disorders. Since altered body composition, decrease of skeletal muscle mass, and development of pathologically changed mesenteric white adipose tissue are well-known features of IBD and especially of Crohn's disease, we discuss the possible crosstalk between adipokines and myokines released from skeletal muscle during exercise with moderate or forced intensity. The emerging role of microbiota and the antioxidative and anti-inflammatory enzymes such as intestinal alkaline phosphatase is also discussed, in order to open new avenues for the therapy against intestinal perturbations associated with IBD.

The Role of Adipose Tissue in the Pathogenesis and Therapeutic Outcomes of Inflammatory Bowel Disease

Though historically regarded as an inert energy store, adipose tissue is a complex endocrine organ, which is increasingly implicated in the pathogenesis of inflammatory bowel disease (IBD). Accumulating evidence points to visceral adipose tissue and specifically to its mesenteric component, or “creeping fat” as impacting on the disease course through its immunomodulatory properties. On the one hand, mesenteric fat acts as a physical barrier to inflammation and is involved in controlling host immune response to translocation of gut bacteria. On the other hand, however, there exists a strong link between visceral fat and complicated course of the disease with unfavorable therapeutic outcomes. Furthermore, “creeping fat” appears to play different roles in different IBD phenotypes, with the greatest pathogenetic contribution probably to an ileal form of Crohn’s disease. In this review, we summarize and discuss the existing literature on the subject and identify high-priority areas for future research. It may be that a better understanding of the role of mesenteric fat in IBD will determine new therapeutic targets and translate into improved clinical outcomes.

Inclusion of the Mesentery in Ileocolic Resection for Crohn's Disease is Associated With Reduced Surgical Recurrence

BACKGROUND AND AIMS

Inclusion of the mesentery during resection for colorectal cancer is associated with improved outcomes but has yet to be evaluated in Crohn's disease. This study aimed to determine the rate of surgical recurrence after inclusion of mesentery during ileocolic resection for Crohn's disease.

METHODS

Surgical recurrence rates were compared between two cohorts. Cohort A [n = 30] underwent conventional ileocolic resection where the mesentery was divided flush with the intestine. Cohort B [n = 34] underwent resection which included excision of the mesentery. The relationship between mesenteric disease severity and surgical recurrence was determined in a separate cohort [n = 94]. A mesenteric disease activity index was developed to quantify disease severity. This was correlated with the Crohn's disease activity index and the fibrocyte percentage in circulating white cells.

RESULTS

Cumulative reoperation rates were 40% and 2.9% in cohorts A and B [P = 0.003], respectively. Surgical technique was an independent determinant of outcome [P = 0.007]. Length of resected intestine was shorter in cohort B, whilst lymph node yield was higher [12.25 ± 13 versus 2.4 ± 2.9, P = 0.002]. Advanced mesenteric disease predicted increased surgical recurrence [Hazard Ratio 4.7, 95% Confidence Interval: 1.71-13.01, P = 0.003]. The mesenteric disease activity index correlated with the mucosal disease activity index [r = 0.76, p < 0.0001] and the Crohn's disease activity index [r = 0.70, p < 0.0001]. The mesenteric disease activity index was significantly worse in smokers and correlated with increases in circulating fibrocytes.

CONCLUSIONS

Inclusion of mesentery in ileocolic resection for Crohn's disease is associated with reduced recurrence requiring reoperation.

The role of obesity in inflammatory bowel disease

In just over a generation overweight and obesity has become a worldwide health concern. The ramifications for this on future health care costs and longevity are consequent, whilst increased adiposity is a harbinger for diabetes, kidney and bone failure, and cancer. An area of intense interest where the role of adiposity is avidly discussed is in inflammatory bowel disease (IBD), which presents mainly as Crohn's disease (CD) and ulcerative colitis (UC). Studies in patients associating IBD with a western diet are divergent. Nevertheless, elegant studies have found gene polymorphisms in humans that in murine models parallel the inflammatory and gut microbiome changes seen in IBD patients. However, an area not to be ignored are the alterations in adipocyte function with ensuing adiposity, in particular and a focus of this review, the dysregulation of the levels of adipocytokines such as leptin and adiponectin. Herein, we present and discuss the known influences of a western diet on IBD in patients and rodent models and how adipocytokines could influence the IBD disease process.

The role of adipose tissue in the pathogenesis of Crohn's disease

Crohn's disease (CD) is a chronic, immune system-mediated inflammatory disease affecting gastrointestinal (GI) tract. The pathogenesis of the intestinal lesions is not entirely explained and understood: excessive activation of the immune system may come as a result of the interaction of environmental, genetic and infectious factors and the mediation of abnormal intestinal flora. The main objective of the current study is to further identify the role of adipose tissue in the pathogenesis of CD. Alterations in body fat distribution, accumulation of intra-abdominal white adipose tissue (WAT) and mesenteric obesity are well-known features of CD. Up to date, data concerning the role of WAT in the pathogenesis of CD is limited with only a few studies on the relationship between WAT and the course of the disease, as well as pro- and anti-inflammatory cytokine profile and general immune system functioning. In this review, we focus on the importance of physiological and pathophysiological WAT functions and secreted adipokines, which seem to have a vital role in the inflammatory and fibrotic processes in CD sufferers.

Hyperadiponectinemia During Infliximab Induction Therapy in Pediatric Crohn Disease

OBJECTIVES

The inflammatory process in Crohn disease (CD) involves the visceral fat, characterized by adipocyte hyperplasia and altered adipose tissue and serum concentrations of tumor necrosis factor (TNF), leptin, adiponectin and resistin. We investigated the effect of anti-TNF therapy with infliximab (IFX) on serum adipokine levels in pediatric CD.

METHODS

Serum concentrations of resistin (ng/mL), leptin (ng/mL), and total adiponectin (μg/mL) were assessed by enzyme-linked immunosorbent assays (ELISA) in 18 pediatric CD patients (mean age 15.0 ± 1.5 years) before first, second, and fourth IFX infusion (weeks 0, 2, and 14) and compared with baseline values from sex- and BMI-matched healthy controls (HC, mean age 13.4 ± 1.6 years).

RESULTS

At baseline, CD patients (mean age 15.0 ± 1.5 years, 10 of 18 boys) compared with HC (13.4 ± 1.6 years, 7 of 15 boys) had higher resistin levels (median 14.7 ng/mL, range 5.1-50.5 vs 7.3 ng/mL, 0.5-14.5); P = 0.0002). At weeks 2 and 14, resistin decreased to 6.9 ng/mL (2.9-16.8) (P < 0.0001) and 9.2 ng/mL (4.1-20.6; P = 0.0011), respectively. Leptin and adiponectin were comparable between patients and HC at baseline. Leptin increased in girls from 9.5 ng/mL (4.0-30.1) to 16.0 ng/mL (7.9-35.2; P = 0.0156) and 17.2 ng/mL (10.8- 26.8; P = 0.1953) at weeks 0, 2, and 14 respectively; with a trend in boys from 2 (0.6-12.9) to 2.8 (1.7-8.6; P = 0.0840) and 3.3 (1.3-4.6; P = 0.1309). Adiponectin peaked initially from 7.8 μg/mL (4.6-11.9) at week 0 to 9.2 μg/mL (4.1-20.7; P = 0.0005) at week 2 and thereafter fell to 6.5 μg/mL (3.0-12.7; P = 0.0182) at week 14.

CONCLUSIONS

TNF blockade is associated with changes in circulating adipokines. The marked early increase of the potent anti-inflammatory adiponectin may contribute to the rapid response to IFX in CD.

Adiponectin and adiponectin receptor 1 overexpression enhance inflammatory bowel disease

BACKGROUND

Adiponectin (ADN) is an adipokine derived from adipocytes. It binds to adiponectin receptor 1 and 2 (AdipoR1 and R2) to exert its function in regulating whole-body energy homeostasis and inflammatory responses. However, the role of ADN-AdipoR1 signaling in intestinal inflammation is controversial, and its role in the regulation of neutrophils is still unclear. Our goal was to clarify the role of AdipoR1 signaling in colitis and the effects on neutrophils.

METHODS

We generated porcine AdipoR1 transgenic mice (pAdipoR1 mice) and induced murine colitis using dextran sulfate sodium (DSS) to study the potential role of AdipoR1 in inflammatory bowel disease. We also treated a THP-1 macrophage and a HT-29 colon epithelial cell line with ADN recombinant protein to study the effects of ADN on inflammation.

RESULTS

After inducing murine colitis, pAdipoR1 mice developed more severe symptoms than wild-type (WT) mice. Treatment with ADN increased the expression of pro-inflammatory factors in THP-1 and HT-29 cells. Moreover, we also observed that the expression of cyclooxygenase2 (cox2), neutrophil chemokines (CXCL1, CXCL2 and CXCL5), and the infiltration of neutrophils were increased in the colon of pAdipoR1 mice.

CONCLUSIONS

Our study showed that ADN-AdipoR1 signaling exacerbated colonic inflammation through two possible mechanisms. First, ADN-AdipoR1 signaling increased pro-inflammatory factors. Second, AdipoR1 enhanced neutrophil chemokine expression and recruited neutrophils into the colonic tissue to increase inflammation.

Association Between Adipokines Levels with Inflammatory Bowel Disease (IBD): Systematic Reviews

BACKGROUND

A combination of genetic and environmental factors is involved in the etiology of inflammatory bowel disease (IBD). Recent studies have shown that adipocytes play a crucial role, by actively participating in systemic immune responses in IBD patients. But findings remain controversial. To the best of our knowledge, no systematic review has evaluated the roles of adipokines in IBD, considering which this systematic review was undertaken to summarize the effects of these adipokines in IBD pathogenesis.

METHODS

For this review, articles published between 1980 and 2016 were identified from the PubMed, EMBASE, Scopus, and Cochrane and Google scholar databases. Thirteen articles were ultimately selected for inclusion in this systematic review.

RESULTS

Findings of the present study indicate that some of the adipokines such as leptin, adiponectin and resistin are associated with disease severity, body composition and glucose hemostasis in IBD patients, although some of these associations are stronger than others.

CONCLUSIONS

Overall findings indicate that some adipokines may play a crucial role in IBD severity or other IBD related outcomes. Further studies are recommended to confirm the results.

Are adipocytokines inflammatory or metabolic mediators in patients with inflammatory bowel disease?

This study examined the adiponectin and leptin levels and insulin resistance (IR) in patients with inflammatory bowel disease (IBD) and the associations between these factors and IBD characteristics. Fasting serum leptin, adiponectin, glucose, and insulin levels, as well as inflammatory parameters, were measured in 105 patients with IBD (49 patients with Crohn’s disease [CD], 56 patients with ulcerative colitis [UC]) and 98 healthy controls [HC]. IR was evaluated using the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR). Disease activity and severity in patients with UC were evaluated using the Truelove–Witts index, and patients with CD were evaluated using the Crohn’s Disease Activity Index. Serum adiponectin levels were found to be significantly lower in patients with CD and UC (p<0.001). Serum leptin levels were also found to be significantly higher in both the UC and CD groups (p<0.001). When HOMA-IR levels were compared, no significant difference was detected for either the CD or UC groups compared with the controls. In conclusion, it was shown that leptin levels increased and adiponectin levels decreased in patients with IBD, which is thought to be related to chronic inflammation. The effects of adipocytokines in patients with IBD with inflammatory and metabolic processes need to be investigated in further broader studies.

The Impact of Western Diet and Nutrients on the Microbiota and Immune Response at Mucosal Interfaces

Recent findings point toward diet having a major impact on human health. Diets can either affect the gut microbiota resulting in alterations in the host’s physiological responses or by directly targeting the host response. The microbial community in the mammalian gut is a complex and dynamic system crucial for the development and maturation of both systemic and mucosal immune responses. Therefore, the complex interaction between available nutrients, the microbiota, and the immune system are central regulators in maintaining homeostasis and fighting against invading pathogens at mucosal sites. Westernized diet, defined as high dietary intake of saturated fats and sucrose and low intake of fiber, represent a growing health risk contributing to the increased occurrence of metabolic diseases, e.g., diabetes and obesity in countries adapting a westernized lifestyle. Inflammatory bowel diseases (IBD) and asthma are chronic mucosal inflammatory conditions of unknown etiology with increasing prevalence worldwide. These conditions have a multifactorial etiology including genetic factors, environmental factors, and dysregulated immune responses. Their increased prevalence cannot solely be attributed to genetic considerations implying that other factors such as diet can be a major contributor. Recent reports indicate that the gut microbiota and modifications thereof, due to a consumption of a diet high in saturated fats and low in fibers, can trigger factors regulating the development and/or progression of both conditions. While asthma is a disease of the airways, increasing evidence indicates a link between the gut and airways in disease development. Herein, we provide a comprehensive review on the impact of westernized diet and associated nutrients on immune cell responses and the microbiota and how these can influence the pathology of IBD and asthma.

Gastrointestinal Complications of Obesity

Obesity usually is associated with morbidity related to diabetes mellitus and cardiovascular diseases. However, there are many gastrointestinal and hepatic diseases for which obesity is the direct cause (eg, nonalcoholic fatty liver disease) or is a significant risk factor, such as reflux esophagitis and gallstones. When obesity is a risk factor, it may interact with other mechanisms and result in earlier presentation or complicated diseases. There are increased odds ratios or relative risks of several gastrointestinal complications of obesity: gastroesophageal reflux disease, erosive esophagitis, Barrett's esophagus, esophageal adenocarcinoma, erosive gastritis, gastric cancer, diarrhea, colonic diverticular disease, polyps, cancer, liver disease including nonalcoholic fatty liver disease, cirrhosis, hepatocellular carcinoma, gallstones, acute pancreatitis, and pancreatic cancer. Gastroenterologists are uniquely poised to participate in the multidisciplinary management of obesity as physicians caring for people with obesity-related diseases, in addition to their expertise in nutrition and endoscopic interventions.

Beneficial Effect of Voluntary Exercise on Experimental Colitis in Mice Fed a High-Fat Diet: The Role of Irisin, Adiponectin and Proinflammatory Biomarkers. Nutrients. 2017;9. [PMID: 28425943 PMCID: PMC5409749 DOI: 10.3390/nu9040410]

Inflammatory bowel diseases (IBDs) are a heterogeneous group of disorders exhibited by two major phenotypic forms: Crohn‘s disease and ulcerative colitis. Although the aetiology of IBD is unknown, several factors coming from the adipose tissue and skeletal muscles, such as cytokines, adipokines and myokines, were suggested in the pathogenesis of ulcerative colitis; however, it has not been extensively studied whether voluntary exercise can ameliorate that disorder. We explored the effect of moderate exercise (i.e., voluntary wheel running) on the disease activity index (DAI), colonic blood flow (CBF), plasma irisin and adiponectin levels and real-time PCR expression of proinflammatory markers in mesenteric fat in mice with 2,4,6-trinitrobenzenesulfonic acid (TNBS) colitis fed a high-fat diet (HFD) compared to those on a standard chow diet (SD). Macroscopic and microscopic colitis in sedentary SD mice was accompanied by a significant fall in CBF, some increase in colonic tissue weight and a significant increase in the plasma levels of tumour necrosis factor-alpha (TNF-α), IL-6, monocyte chemotactic protein 1 (MCP-1) and IL-13 (p < 0.05). In sedentary HFD mice, colonic lesions were aggravated, colonic tissue weight increased and the plasma TNF-α, IL-6, MCP-1, IL-1β and leptin levels significantly increased. Simultaneously, a significant decrease in the plasma irisin and adiponectin levels was observed in comparison with SD mice (p < 0.05). Exercise significantly decreased macroscopic and microscopic colitis, substantially increased CBF and attenuated the plasma TNF-α, IL-6, MCP-1, IL-1β and leptin levels while raising the plasma irisin and the plasma and WAT concentrations of adiponectin in HFD mice (p < 0.05). We conclude that: (1) experimental colitis is exacerbated in HFD mice, possibly due to a fall in colonic microcirculation and an increase in the plasma and mesenteric fat content of proinflammatory biomarkers; and (2) voluntary physical activity can attenuate the severity of colonic damage in mice fed a HFD through the release of protective irisin and restoration of plasma adiponectin.

Transcriptional and Molecular Pathways Activated in Mesenteric Adipose Tissue and Intestinal Mucosa of Crohn's Disease Patients

Crohn's disease (CD) is a chronic inflammatory disorder, characterized by cytokine imbalance and transcription signaling pathways activation. In addition, the increase of mesenteric adipose tissue (MAT) near the affected intestinal area is a hallmark of CD. Therefore, we evaluated the transcription signaling pathways and cytokines expression in intestinal mucosa and MAT of active CD patients. Ten patients with ileocecal CD and eight with noninflammatory diseases were studied. The biopsies of intestinal mucosa and MAT were snap-frozen and protein expression was determined by immunoblotting. RNA levels were measured by qPCR. The pIkB/IkB ratio and TNFα level were significantly higher in intestinal mucosa of CD when compared to controls. However, STAT1 expression was similar between intestinal mucosa of CD and controls. Considering the MAT, the pIkB/IkB ratio was significantly lower and the anti-inflammatory cytokine IL10 was significantly higher in CD when compared to controls. Finally, the protein content of pSTAT1 was higher in MAT of CD compared to controls. These findings reinforce the predominance of the proinflammatory NF-kB pathway in CD intestinal mucosa. For the first time, we showed the activation of STAT1 pathway in MAT of CD patients, which may help to understand the physiopathology of this immune mediated disease.

Plasma ghrelin and leptin in patients with inflammatory bowel disease and its association with nutritional status

BACKGROUND/AIMS

Ghrelin and leptin are thought to play a role in the loss of appetite in active inflammatory bowel disease (IBD). This study seeks to probe into the association of these markers with regards to IBD and the nutritional status of these patients. A case-control study was conducted between May 2015 and March 2016 at King Khalid University Hospital (KKUH). Thirty-one patients with IBD (both active and non-active) and forty-one healthy controls (both non-fasting and fasting) were recruited.

PATIENTS AND METHODS

Plasma ghrelin and leptin levels were determined using an enzyme immunoassay (EIA) technique. The nutritional status was determined through the standardized Mini-Nutritional Assessment (MNA) questionnaire.

RESULTS

The difference in the plasma ghrelin between active (263.7 pg/mL) and non-active (108 pg/mL) cases was significant (P= 0.02). The difference in mean plasma leptin level between active cases (229.4 pg/mL) vs. non-active cases (359.7 pg/mL) was insignificant (P= 0.4). In fasting (2028.6 pg/mL) and non-fasting controls (438.8 pg/mL), the mean plasma ghrelin values was significantly different (P< 0.01). In contrast, the plasma leptin level difference between fasting (727.3 pg/mL) and non-fasting (577 pg/mL) controls was insignificant (P= 0.14). There is a statistically significant association in mean ghrelin levels between the case group and the control group (P< 0.01). With regards to nutritional status, the mean MNA score of active cases compared to fasting controls was 18.8 ± 5 vs. 20.8 ± 3.8, respectively (P< 0.01) Conclusion: Ghrelin levels were lower in the active IBD cases compared to the inactive ones, signifying an underlying pathology as etiology to this phenomenon. Furthermore, ghrelin levels were significantly lower in both case groups compared to the controls. These findings, along with the disparity in the MNA scores, insinuate a possible link between hormone levels and the loss of appetite from which these patients suffer.

Adipokines and the role of visceral adipose tissue in inflammatory bowel disease

Recently, adipocytes have been recognized as actively participating in local and systemic immune responses via the secretion of peptides detectable in relevant levels in the systemic circulation, the so-called "adipo(cyto)kines". Multiple studies appearing within the last 10-15 years have focused on the possible impact of adipose tissue depots on inflammatory bowel disease (IBD). Consequently, various hypotheses regarding the role of different adipokines in inflammatory diseases in general and in intestinal inflammatory processes in particular have been developed and have been further refined in recent years. After a focused summary of the data reported concerning the impact of visceral adipose tissue on IBD, such as Crohn's disease and ulcerative colitis, our review focuses on recent developments indicating that adipocytes as part of the innate immune system actively participate in antimicrobial host defenses in the context of intestinal bacterial translocation, which are of utmost importance for the homeostasis of the whole organism. Modulators of adipose tissue function and regulators of adipokine secretion, as well as modifiers of adipocytic pattern recognition molecules, might represent future potential drug targets in IBD.

The mesentery in Crohn's disease: friend or foe?

PURPOSE OF REVIEW

This article assesses the role of the mesentery in Crohn's disease.

RECENT FINDINGS

The mesentery is centrally positioned both anatomically and physiologically. Overlapping mesenteric and submucosal mesenchymal contributions are important in the pathobiology of Crohn's disease. Mesenteric contributions explain the topographic distribution of Crohn's disease in general and mucosal disease in particular. Operative strategies that are mesenteric based (i.e. mesocolic excision) may reduce rates of postoperative recurrence.

SUMMARY

The net effect of mesenteric events in Crohn's disease is pathologic. This can be targeted by operative means.

VIDEO ABSTRACT

http://links.lww.com/COG/A18.

Common links between metabolic syndrome and inflammatory bowel disease: Current overview and future perspectives

Metabolic syndrome (MS) features a constellation of central obesity, dyslipidemia, impaired glucose metabolism and often hypertension joined by insulin resistance and chronic inflammation. All these elements greatly raise patient's risk of cardiovascular disease and type 2 diabetes, resulting in an increased mortality. Metabolic syndrome affects approximately 20-25% of the world's adult population and thus it is essential to study its pathophysiology and seek new pharmacological targets. There is a thoroughly studied link between MS and inflammatory diseases of the gastrointestinal (GI) system, i.e. steatohepatitis. However, recent findings also indicate similarities in pathophysiological features between MS and inflammatory bowel disease (IBD), including adipose tissue dysregulation, inadequate immune response, and inflammation. In this review we aim to outline the pathophysiology of MS and emphasize the aspects revealed recently, such as mineralocorticoid activity, involvement of sex hormones and an accompanying increase in prolactin secretion. More importantly, we focus on the common links between MS and IBD. Finally, we describe new strategies and drug targets that may be utilized in MS therapy, namely adiponectin mimetics, GLP-1-based multi agonists, ABCA1 agonists and possible role of miRNA. We also discuss the possible utility of selected agents as adjuvants in IBD therapy.

Can exercise affect the course of inflammatory bowel disease? Experimental and clinical evidence

The inflammatory bowel disease (IBD) consisting of Crohn's disease (CD) and ulcerative colitis (UC) are defined as idiopathic, chronic and relapsing intestinal disorders occurring in genetically predisposed individuals exposed to environmental risk factors such as diet and microbiome changes. Since conventional drug therapy is expensive and not fully efficient, there is a need for alternative remedies that can improve the outcome in patients suffering from IBD. Whether exercise, which has been proposed as adjunct therapy in IBD, can be beneficial in patients with IBD remains an intriguing question. In this review, we provide an overview of the effects of exercise on human IBD and experimental colitis in animal models that mimic human disease, although the information on exercise in human IBD are sparse and poorly understood. Moderate exercise can exert a beneficial ameliorating effect on IBD and improve the healing of experimental animal colitis due to the activity of protective myokines such as irisin released from working skeletal muscles. CD patients with higher levels of exercise were significantly less likely to develop active disease at six months. Moreover, voluntary exercise has been shown to exert a positive effect on IBD patients' mood, weight maintenance and osteoporosis. On the other hand, depending on its intensity and duration, exercise can evoke transient mild systemic inflammation and enhances pro-inflammatory cytokine release, thereby exacerbating the gastrointestinal symptoms. We discuss recent advances in the mechanism of voluntary and strenuous exercise affecting the outcome of IBD in patients and experimental animal models.

Combination of Azathioprine and Aminosalicylate Treatment Prevent Risk of Cardiovascular Disease in Women with Ulcerative Colitis by Reducing Inflammation

Background

Ulcerative colitis (UC) is a chronic inflammatory bowel disease with involvement of the immune system. Chronic inflammatory diseases have been associated with increased risk of cardiovascular disease (CVD) but few studies have assessed this risk in patients with UC and the influence of drug treatment. Thus, we evaluated the risk of development of CVD in women with UC in clinical remission, considering the drug treatment.

Material/Methods

Twenty-one women with UC participated in this study: 12 used aminosalicylates (ASA group) and 9 used azathioprine added to aminosalicylates (AZA+ASA group). The healthy control group was matched for age. We evaluated blood pressure, body composition, and biochemical and immunological parameters.

Results

Compared to the respective control group, the UC groups showed expansion of body fat and less lean body mass. Blood pressure, pro-inflammatory cytokines, nitric oxide, C reactive protein, erythrocyte sedimentation rate (ESR), and anti-oxidized LDL antibodies were higher in UC groups. Only AZA+ASA group showed increased anti-inflammatory cytokines (IL-10 and TGF-β). Framingham scores showed higher risk of CVD in UC groups. UC groups were compared and women treated with azathioprine showed reduction of total protein, globulin, ESR, and lymphocytes, with increased IL-6, TNF, IL-10, and TGF-β.

Conclusions

Our data suggest that women with UC in clinical remission have a higher risk for development of atherosclerosis and CVD when compared to the control group, while women treated with azathioprine seem more protected than those treated only with aminosalicylates, due to better regulation of the inflammatory process.

Association of adiponectin receptor (Adipo-R1/-R2) expression and colorectal cancer

INTRODUCTION

Human adiponectin (ApN) is a 30 kDa glycoprotein of 244-amino acids which is extensively produced by adipocytes. ApN acts via two receptors, namely adiponectin receptor-1 (Adipo-R1) and adiponectin receptor-2 (Adipo-R2). Studies have shown the presence of Adipo-R1 and Adipo-R2 expression immunohistochemically in human colorectal cancers (CRCs). However, only a few studies exist which investigated effects of adiponectin receptor expression on CRC characteristics.

OBJECTIVES

In the present study, we aimed to explore Adipo-R1/-R2 expression in human colorectal cancers and any association with clinicopathological characteristics and survival.

MATERIALS AND METHODS

The study enrolled 58 colorectal cancer patients with tumor resection and a control group of 30 subjects with normal colon mucosa.

RESULTS

Positivity for Adipo-R1/-R2 expression was significantly more common in the control group in comparison to the patient group (both p<0.001). There was no significant association between Adipo-R1/-R2 expression and clinicopathological characteristics including age, sex tumor location, pTNM stage, Duke's stage, metastasis, histological differentiation, perineural invasion, venous invasion sex, lymphatic invasion, cancer-related mortality, tumor size and recurrence. Adipo- R1/-R2 positivity was also not significantly linked to progression-free or overall survival [p values (0.871, 0.758 ) and (0.274, 0.232), respectively].

CONCLUSIONS

Although significantly reduced Adipo-R1/-R2 expression was found in colorectal cancer patients, it had no influence on survival.

Metabolic inflammation in inflammatory bowel disease: crosstalk between adipose tissue and bowel

Epidemiological studies show that both the incidence of inflammatory bowel disease (IBD) and the proportion of people with obesity and/or obesity-associated metabolic syndrome increased markedly in developed countries during the past half century. Obesity is also associated with the development of more active IBD and requirement for hospitalization and with a decrease in the time span between diagnosis and surgery. Patients with IBD, especially Crohn's disease, present fat-wrapping or "creeping fat," which corresponds to ectopic adipose tissue extending from the mesenteric attachment and covering the majority of the small and large intestinal surface. Mesenteric adipose tissue in patients with IBD presents several morphological and functional alterations, e.g., it is more infiltrated with immune cells such as macrophages and T cells. All these lines of evidence clearly show an association between obesity, adipose tissue, and functional bowel disorders. In this review, we will show that the mesenteric adipose tissue and creeping fat are not innocent by standers but actively contribute to the intestinal and systemic inflammatory responses in patients with IBD. More specifically, we will review evidence showing that adipose tissue in IBD is associated with major alterations in the secretion of cytokines and adipokines involved in inflammatory process, in adipose tissue mesenchymal stem cells and adipogenesis, and in the interaction between adipose tissue and other intestinal components (immune, lymphatic, neuroendocrine, and intestinal epithelial systems). Collectively, these studies underline the importance of adipose tissue for the identification of novel therapeutic approaches for IBD.

Moderate exercise training attenuates the severity of experimental rodent colitis: the importance of crosstalk between adipose tissue and skeletal muscles

Although progress has been recently made in understanding of inflammatory bowel diseases (IBD), their etiology is unknown apart from several factors from adipose tissue and skeletal muscles such as cytokines, adipokines, and myokines were implicated in the pathogenesis of ulcerative colitis. We studied the effect high-fat diet (HFD; cholesterol up to 70%), low-fat diet (LFD; cholesterol up to 10%), and the normal diet (total fat up to 5%) in rats with TNBS colitis forced to treadmill running exercise (5 days/week) for 6 weeks. In nonexercising HFD rats, the area of colonic damage, colonic tissue weight, the plasma IL-1β, TNF-α, TWEAK, and leptin levels, and the expression of IL-1β-, TNF-α-, and Hif1α mRNAs were significantly increased and a significant fall in plasma adiponectin and irisin levels was observed as compared to LFD rats. In HFD animals, the exercise significantly accelerated the healing of colitis, raised the plasma levels of IL-6 and irisin, downregulated the expression of IL-1β, TNF-α, and Hif1α, and significantly decreased the plasma IL-1β, TNF α, TWEAK, and leptin levels. We conclude that HFD delays the healing of colitis in trained rats via decrease in CBF and plasma IL-1β, TNF-α, TWEAK, and leptin levels and the release of protective irisin.

The bone and fat connection in inflammatory bowel diseases

Osteopenia and osteoporosis are common manifestations in inflammatory bowel diseases (IBD) but the pathogenetic mechanism of bone loss in IBD is only partially understood. There is evidence that fat mass is an important determinant of the bone mineral density and adipose-derived factors seem to play an important role for the association between fat mass and bone mass. The association between adiposity and low bone density is rather poorly studied in IBD, but emerging data on adipokines in IBD in relation to osteoporosis provide a novel pathophysiological concept that may shed light on the etiology of bone loss in IBD. It could be suggested that adipokines interfere in bone metabolism by altering the sensitive balance between osteoblasts and osteoclasts although further studies in this setting are needed.

Role of fat and adipokines in intestinal inflammation

PURPOSE OF REVIEW

This review summarizes current knowledge on the contribution of mesenteric adipose tissue in intestinal inflammation. We will describe the cellular and humoral characteristics of creeping fat, their potential impact for Crohn's disease and propose a working model for the critical interplay between the creeping fat and the inflamed intestine.

RECENT FINDINGS

Creeping fat can be distinguished from healthy adipose tissue by its distinctively small adipocytes, by a specific microenvironment defined by high levels of adipokines and by a dominant immune cell infiltration. In Crohn's disease transmural inflammation facilitates increased bacterial translocation into the creeping fat. Translocalizing antigens can directly activate (pre)adipocytes via innate receptors. Adipocyte-derived mediators modulate phenotype and function of innate and adaptive immune cells. Activated (pre)adipocytes and adipokine-modulated immune cells might support a degree of inflammatory activation within the creeping fat that allows competent immune defense against exogenous factors while preventing systemic inflammation.

SUMMARY

Fat tissue as an active organ in health and disease has been ignored for too long. The last few years of research provided evidence for the complex metabolic and immunological functions of adipose tissue. On the basis of the available data, creeping fat in Crohn's disease exerts a protective function by a localized anti-inflammatory effect, thus preventing a systemic inflammatory response.

Defective apoptosis in intestinal and mesenteric adipose tissue of Crohn's disease patients

BACKGROUND

Crohn's disease (CD) is associated with complex pathogenic pathways involving defects in apoptosis mechanisms. Recently, mesenteric adipose tissue (MAT) has been associated with CD ethiopathology, since adipose thickening is detected close to the affected intestinal area. However, the potential role of altered apoptosis in MAT of CD has not been addressed.

AIMS

To evaluate apoptosis in the intestinal mucosa and MAT of patients with CD.

METHODS

Samples of intestinal mucosa and MAT from patients with ileocecal CD and from non-inflammatory bowel diseases patients (controls) were studied. Apoptosis was assessed by TUNEL assay and correlated with the adipocytes histological morphometric analysis. The transcriptional and protein analysis of selected genes and proteins related to apoptosis were determined.

RESULTS

TUNEL assay showed fewer apoptotic cells in CD, when compared to the control groups, both in the intestinal mucosa and in MAT. In addition, the number of apoptotic cells (TUNEL) correlated significantly with the area and perimeter of the adipose cells in MAT. Transcriptomic and proteomic analysis reveal a significantly lower transcript and protein levels of Bax in the intestinal mucosa of CD, compared to the controls; low protein levels of Bax were found localized in the lamina propria and not in the epithelium of this tissue. Furthermore, higher level of Bcl-2 and low level of Caspase 3 were seen in the MAT of CD patients.

CONCLUSION

The defective apoptosis in MAT may explain the singular morphological characteristics of this tissue in CD, which may be implicated in the pathophysiology of the disease.

The role of physical exercise in inflammatory bowel disease

We reviewed and analyzed the relationship between physical exercise and inflammatory bowel disease (IBD) which covers a group of chronic, relapsing, and remitting intestinal disorders including Crohn's disease (CD) and ulcerative colitis. The etiology of IBD likely involves a combination of genetic predisposition and environmental risk factors. Physical training has been suggested to be protective against the onset of IBD, but there are inconsistencies in the findings of the published literature. Hypertrophy of the mesenteric white adipose tissue (mWAT) is recognized as a characteristic feature of CD, but its importance for the perpetuation of onset of this intestinal disease is unknown. Adipocytes synthesize proinflammatory and anti-inflammatory cytokines. Hypertrophy of mWAT could play a role as a barrier to the inflammatory process, but recent data suggest that deregulation of adipokine secretion is involved in the pathogenesis of CD. Adipocytokines and macrophage mediators perpetuate the intestinal inflammatory process, leading to mucosal ulcerations along the mesenteric border, a typical feature of CD. Contracting skeletal muscles release biologically active myokines, known to exert the direct anti-inflammatory effects, and inhibit the release of proinflammatory mediators from visceral fat. Further research is required to confirm these observations and establish exercise regimes for IBD patients.

Adiponectin as a routine clinical biomarker

Adiponectin is a protein synthesized and secreted predominantly by adipocytes into the peripheral blood. However, circulating adiponectin level is inversely related with body weight, especially visceral fat accumulation. The mechanism of this paradoxical relation remains obscure. Low circulating adiponectin concentrations (hypoadiponectinemia; <4 μg/mL) are associated with a variety of diseases, including dysmetabolism (type 2 diabetes, insulin resistance, hypertension, dyslipidemia, metabolic syndrome, hyperuricemia), atherosclerosis (coronary artery disease, stroke, peripheral artery disease), sleep apnea, non-alcoholic fatty liver disease, gastritis and gastro-esophageal reflux disease, inflammatory bowel diseases, pancreatitis, osteoporosis, and cancer (endometrial cancer, postmenopausal breast cancer, leukemia, colon cancer, gastric cancer, prostate cancer). On the other hand, hyperadiponectinemia is associated with cardiac, renal and pulmonary diseases. This review article focuses on the significance of adiponectin as a clinical biomarker of obesity-related diseases. Routine measurement of adiponectin in patients with lifestyle-related diseases is highly recommended.

Fibrogenesis and fibrosis in inflammatory bowel diseases: Good and bad side of same coin?

Fibrogenesis in inflammatory bowel diseases is a complex phenomenon aimed at mucosal repair. However, it may provoke intestinal fibrosis with the development of strictures which require surgery. Therefore, fibrogenesis may be considered as a “two-faced” process when related to chronic intestinal inflammation. Many types of cells may be converted into the fibrogenic phenotype at different levels of the intestinal wall. A complex interaction of cytokines, adhesion molecules and growth factors is involved in the process. We report an overview of recent advances in molecular mechanisms of stricturizing Crohn’s disease (CD) including the potential role of trasforming growth factor beta, protein kinase C and Ras, Raf and ERK proteins. Fibrotic growth factors such as vascular endothelial growth factor and platelet-derived growth factor, as well as the Endothelial-to-Mesenchymal Transition induced by transforming growth factor-β, are considered. Finally, our experience, focused on tumor necrosis factor α (the main cytokine of inflammatory bowel diseases) and the link between syndecan 1 (a heparan sulphate adhesion molecule) and basic fibroblast growth factor (a strong stimulator of collagen synthesis) is described. We hypothesize a possible molecular pattern for mucosal healing as well as how its deregulation could be involved in fibrotic complications of CD. A final clinical point is the importance of performing an accurate evaluation of the presence of fibrotic strictures before starting anti-tumor necrosis α treatment, which could worsen the lesions.