Decreased expression of the NLRP6 inflammasome is associated with increased intestinal permeability and inflammation in obesity with type 2 diabetes.

BACKGROUND: Obesity-associated dysfunctional intestinal permeability contributes to systemic chronic inflammation leading to the development of metabolic diseases. The inflammasomes constitute essential components in the regulation of intestinal homeostasis. We aimed to determine the impact of the inflammasomes in the regulation of gut barrier dysfunction and metabolic inflammation in the context of obesity and type 2 diabetes (T2D). METHODS: Blood samples obtained from 80 volunteers (n = 20 normal weight, n = 21 OB without T2D, n = 39 OB with T2D) and a subgroup of jejunum samples were used in a case-control study. Circulating levels of intestinal damage markers and expression levels of inflammasomes as well as their main effectors (IL-1ß and IL-18) and key inflammation-related genes were analyzed. The impact of inflammation-related factors, different metabolites and Akkermansia muciniphila in the regulation of inflammasomes and intestinal integrity genes was evaluated. The effect of blocking NLRP6 by using siRNA in inflammation was also studied. RESULTS: Increased circulating levels (P < 0.01) of the intestinal damage markers endotoxin, LBP, and zonulin in patients with obesity decreased (P < 0.05) after weight loss. Patients with obesity and T2D exhibited decreased (P < 0.05) jejunum gene expression levels of NLRP6 and its main effector IL18 together with increased (P < 0.05) mRNA levels of inflammatory markers. We further showed that while NLRP6 was primarily localized in goblet cells, NLRP3 was localized in the intestinal epithelial cells. Additionally, decreased (P < 0.05) mRNA levels of Nlrp1, Nlrp3 and Nlrp6 in the small intestinal tract obtained from rats with diet-induced obesity were found. NLRP6 expression was regulated by taurine, parthenolide and A. muciniphila in the human enterocyte cell line CCL-241. Finally, a significant decrease (P < 0.01) in the expression and release of MUC2 after the knockdown of NLRP6 was observed. CONCLUSIONS: The increased levels of intestinal damage markers together with the downregulation of NLRP6 and IL18 in the jejunum in obesity-associated T2D suggest a defective inflammasome sensing, driving to an impaired epithelial intestinal barrier that may regulate the progression of multiple obesity-associated comorbidities.

Clinical Perspectives, Eligibility, and Success Criteria for Bariatric/Metabolic Surgery.

Obesity is a worldwide chronic, complex, and progressive disease that poses a challenge for physicians to pursue optimal therapeutic decision making. This chapter focuses on the definition of obesity, based on excessive fat accumulation, and thus underscores the importance of body composition, and the clinical tools used to diagnose it in the context of excess weight, metabolic alteration, and obesity-associated comorbidity development. Additionally, it addresses the indications for surgery that are currently applicable and the description of the different types of patients who could benefit the most from the surgical management of excessive body fat and its associated metabolic derangements and quality of life improvement. Furthermore, it also highlights plausible underlying mechanisms of action for the beneficial effects following bariatric/metabolic surgery.

Increased Aquaporin-7 Expression Is Associated with Changes in Rat Brown Adipose Tissue Whitening in Obesity: Impact of Cold Exposure and Bariatric Surgery.

Glycerol is a key metabolite for lipid accumulation in insulin-sensitive tissues. We examined the role of aquaporin-7 (AQP7), the main glycerol channel in adipocytes, in the improvement of brown adipose tissue (BAT) whitening, a process whereby brown adipocytes differentiate into white-like unilocular cells, after cold exposure or bariatric surgery in male Wistar rats with diet-induced obesity (DIO) (n = 229). DIO promoted BAT whitening, evidenced by increased BAT hypertrophy, steatosis and upregulation of the lipogenic factors Pparg2, Mogat2 and Dgat1. AQP7 was detected in BAT capillary endothelial cells and brown adipocytes, and its expression was upregulated by DIO. Interestingly, AQP7 gene and protein expressions were downregulated after cold exposure (4 °C) for 1 week or one month after sleeve gastrectomy in parallel to the improvement of BAT whitening. Moreover, Aqp7 mRNA expression was positively associated with transcripts of the lipogenic factors Pparg2, Mogat2 and Dgat1 and regulated by lipogenic (ghrelin) and lipolytic (isoproterenol and leptin) signals. Together, the upregulation of AQP7 in DIO might contribute to glycerol influx used for triacylglycerol synthesis in brown adipocytes, and hence, BAT whitening. This process is reversible by cold exposure and bariatric surgery, thereby suggesting the potential of targeting BAT AQP7 as an anti-obesity therapy.

Improved Adipose Tissue Function after Single Anastomosis Duodeno-Ileal Bypass with Sleeve-Gastrectomy (SADI-S) in Diet-Induced Obesity.

Bariatric surgery has been recognized as the safest and most effective procedure for controlling type 2 diabetes (T2D) and obesity in carefully selected patients. The aim of the present study was to compare the effects of Sleeve Gastrectomy (SG) and Single Anastomosis Duodenoileal Bypass with SG (SADI-S) on the metabolic profile of diet-induced obese rats. A total of 35 four-week-old male Wistar rats were submitted to surgical interventions (sham operation, SG and SADI-S) after 4 months of being fed a high-fat diet. Body weight, metabolic profile and the expression of molecules involved in the control of subcutaneous white (SCWAT), brown (BAT) and beige (BeAT) adipose tissue function were analyzed. SADI-S surgery was associated with significantly decreased amounts of total fat pads (p < 0.001) as well as better control of lipid and glucose metabolism compared to the SG counterparts. An improved expression of molecules involved in fat browning in SCWAT and in the control of BAT and BeAT differentiation and function was observed following SADI-S. Together, our findings provide evidence that the enhanced metabolic improvement and their continued durability after SADI-S compared to SG rely, at least in part, on the improvement of the BeAT phenotype and function.

Dermatopontin Influences the Development of Obesity-Associated Colon Cancer by Changes in the Expression of Extracellular Matrix Proteins.

Dysfunctional adipose tissue (AT) in the context of obesity leads to chronic inflammation together with an altered extracellular matrix (ECM) remodelling, favouring cancer development and progression. Recently, the influence of dermatopontin (DPT) in AT remodelling and inflammation has been proposed. We aimed to evaluate the role of DPT in the development of obesity-associated colon cancer (CC). Samples obtained from 73 subjects [26 lean (LN) and 47 with obesity (OB)] were used in a case-control study. Enrolled subjects were further subclassified according to the established diagnostic protocol for CC (42 without CC and 31 with CC). In vitro studies in the adenocarcinoma HT-29 cell line were performed to analyse the impact of pro- and anti-inflammatory mediators on the transcript levels of DPT as well as the effect of DPT on ECM remodelling and inflammation. Although obesity increased (p < 0.05) the circulating levels of DPT, its concentrations were significantly decreased (p < 0.05) in patients with CC. Gene expression levels of DPT in the colon from patients with CC were downregulated and, oppositely, a tendency towards increased mRNA levels in visceral AT was found. We further showed that DPT expression levels in HT-29 cells were enhanced (p < 0.05) by inflammatory factors (LPS, TNF-α and TGF-ß), whereas the anti-inflammatory IL-4 decreased (p < 0.05) its expression levels. We also demonstrated that DPT upregulated (p < 0.05) the mRNA of key molecules involved in ECM remodelling (COL1A1, COL5A3, TNC and VEGFA) whereas decorin (DCN) expression was downregulated (p < 0.05) in HT-29 cells. Finally, we revealed that the adipocyte-conditioned medium obtained from volunteers with OB enhanced (p < 0.01) the expression of DPT in HT-29 and Caco-2 cells. The decreased circulating and expression levels of DPT in the colon together with the tendency towards increased levels in visceral AT in patients with CC and its influence on the expression of ECM proteins suggest a possible role of DPT in the OB-associated CC.

Role of ANGPTL8 in NAFLD Improvement after Bariatric Surgery in Experimental and Human Obesity.

Angiopoietin-like protein 8 (ANGPTL8) is an hepatokine altered in several metabolic conditions, such as obesity, type 2 diabetes, dyslipidemia and nonalcoholic fatty liver disease (NAFLD). We sought to explore whether ANGPTL8 is involved in NAFLD amelioration after bariatric surgery in experimental models and patients with severe obesity. Plasma ANGPTL8 was measured in 170 individuals before and 6 months after bariatric surgery. Hepatic ANGPTL8 expression was evaluated in liver biopsies of patients with severe obesity undergoing bariatric surgery with available liver pathology analysis (n = 75), as well as in male Wistar rats with diet-induced obesity subjected to sham operation, sleeve gastrectomy or Roux-en-Y gastric bypass (RYGB) (n = 65). The effect of ANGPTL8 on lipogenesis was assessed in human HepG2 hepatocytes under palmitate-induced lipotoxic conditions. Plasma concentrations and hepatic expression of ANGPTL8 were increased in patients with obesity-associated NAFLD in relation to the degree of hepatic steatosis. Sleeve gastrectomy and RYGB improved hepatosteatosis and reduced the hepatic ANGPTL8 expression in the preclinical model of NAFLD. Interestingly, ANGPTL8 inhibited steatosis and expression of lipogenic factors (PPARG2, SREBF1, MOGAT2 and DGAT1) in palmitate-treated human hepatocytes. Together, ANGPTL8 is involved in the resolution of NAFLD after bariatric surgery partially by the inhibition of lipogenesis in steatotic hepatocytes.

Decreased Levels of Microfibril-Associated Glycoprotein (MAGP)-1 in Patients with Colon Cancer and Obesity Are Associated with Changes in Extracellular Matrix Remodelling.

OBJECTIVE: The protein microfibril-associated glycoprotein (MAGP)-1 constitutes a crucial extracellular matrix protein. We aimed to determine its impact on visceral adipose tissue (VAT) remodelling during obesity-associated colon cancer (CC). METHODS: Samples obtained from 79 subjects (29 normoponderal (NP) (17 with CC) and 50 patients with obesity (OB) (19 with CC)) were used in the study. Circulating concentrations of MAGP-1 and its gene expression levels (MFAP2) in VAT were analysed. The impact of inflammation-related factors and adipocyte-conditioned media (ACM) on MFAP2 mRNA levels in colon adenocarcinoma HT-29 cells were further analysed. The effects of MAGP-1 in the expression of genes involved in the extracellular matrix (ECM) remodelling and tumorigenesis in HT-29 cells was also explored. RESULTS: Obesity (p < 0.01) and CC (p < 0.001) significantly decreased MFAP2 gene expression levels in VAT whereas an opposite trend in TGFB1 mRNA levels was observed. Increased mRNA levels of MFAP2 after the stimulation of HT-29 cells with lipopolysaccharide (LPS) (p < 0.01) and interleukin (IL)-4 (p < 0.01) together with a downregulation (p < 0.05) after hypoxia mimicked by CoCl2 treatment was observed. MAGP-1 treatment significantly enhanced the mRNA levels of the ECM-remodelling genes collagen type 6 α3 chain (COL6A3) (p < 0.05), decorin (DCN) (p < 0.01), osteopontin (SPP1) (p < 0.05) and TGFB1 (p < 0.05). Furthermore, MAGP-1 significantly reduced (p < 0.05) the gene expression levels of prostaglandin-endoperoxide synthase 2 (COX2/PTGS2), a key gene controlling cell proliferation, growth and adhesion in CC. Interestingly, a significant decrease (p < 0.01) in the mRNA levels of MFAP2 in HT-29 cells preincubated with ACM from volunteers with obesity compared with control media was observed. Conclusion: The decreased levels of MAGP-1 in patients with obesity and CC together with its capacity to modulate key genes involved in ECM remodelling and tumorigenesis suggest MAGP-1 as a link between AT excess and obesity-associated CC development.

Intravenous ustekinumab reinduction as a Crohn's disease rescue strategy following a secondary non-response.

Secondary non-response to biological treatments tends to occur in a high number of patients who undergo treatment with antiTNF, and it has also been observed in patients treated with vedolizumab or ustekinumab. The initial rescue guideline recommends intensifying the treatment by reducing the interval or increasing maintenance dosage. In the case of ustekinumab, the patients who began this treatment prior to its approval for treatment of Crohn's disease, were given a subcutaneous induction with no defined guideline and a maintenance dosage of 90 mg every eight weeks. Following secondary non-response in these patients, it was proposed that rescue be undertaken via intravenous reinduction adjusted for weight. We present a case of a patient with Crohn's disease with failure to respond to infliximab, adalimumab and vedolizumab who began treatment with ustekinumab prior to official approval. There was non-response at eight months but remission was achieved after reinduction with ustekinumab, adjusted for weight. This rescue guideline could be a cost-effective way to reinduce remission in this group of patients.

The onset of ulcerative colitis during treatment with secukinumab: can anti-IL-17A be a trigger for inflammatory bowel disease?

In recent months, cases of IBD have been reported in the context of treatment with secukinumab, a monoclonal antibody that blocks IL-17A and which is used in the treatment of certain rheumatic disorders. We present a case of a patient with psoriatic arthritis, with a first-degree relative who had suffered ulcerative colitis, who presented with onset ulcerative colitis in the weeks following treatment initiation with this drug.

The long-term benefits of bariatric surgery in elderly and super-obese populations.

PURPOSE: to assess the long-term benefits of bariatric surgery in super-obese (body mass index [BMI] ≥ 50) and in elderly obese (age > 60 years) populations. METHODS: one hundred and twenty one patients who underwent laparoscopic Roux-en-Y gastric bypass or laparoscopic sleeve gastrectomy in a university hospital were retrospectively subdivided into the following groups: BMI < 50 vs ≥ 50 and age < 60 vs ≥ 60 years. Weight loss, body composition and comorbidity outcomes were registered after one and six months and one, two, three and five years with 100%, 93%, 89%, 80%, 75% and 60% successful follow-up. RESULTS: the percentage of excess BMI loss (%EBMIL) was comparable between BMI groups and age groups and the difference in the long-term follow up was not statistically significant (p > 0.05). Complication rates, comorbidity resolution, reduction in body fat and increase in fat-free mass were comparable between BMI groups and age groups. Gastric bypass resulted in a greater weight loss compared to sleeve gastrectomy. The % EBMIL was 65.2% vs 46.7% (p = 0.002), 65.8% vs 44.9% (p = 0.004), 64.4% vs 30.5% (p = 0.001), 55.6% vs 17.6% (p = 0.016) at one, two, three and five years postoperative, respectively. Similarly, in the super-obese group, weight loss was more pronounced after gastric bypass versus sleeve gastrectomy. CONCLUSIONS: bariatric surgery in super-obese and elderly populations is an effective and safe weight loss measure with a good comorbidity resolution in the long-term. Gastric bypass is superior to sleeve gastrectomy in terms of long-term weight loss and comorbidity resolution in all the groups investigated.

Eligibility and Success Criteria for Bariatric/Metabolic Surgery.

Obesity is a worldwide main health concern, with a high treatment failure. This chapter focuses on the definition of obesity, based on excessive fat accumulation and thus underscores the importance of body composition, and the clinical tools currently used to diagnose it, mainly body mass index that is only a proxy measure of body composition. It also highlights the importance of the personal commitment to comply to a healthy diet and physical activity recommendations since surgery is most effective when accompanied by lifestyle modifications. Additionally, it addresses the description of types of patients who could benefit most from surgical management of excessive body fat percentage and metabolic derangements, as well as on the indications for surgery that are currently valid.

The incidence of perioperative hypersensitivity reactions: a single-center, prospective, cohort study.

BACKGROUND: The incidence of perioperative hypersensitivity reactions, which can be life-threatening, ranges from 1 in 20,000 to 1 in 1361. These reactions are usually classified as IgE or non-IgE mediated. The aim of this study was to determine the incidence of allergic reactions during general anesthesia in our hospital, to establish the incidence of the allergic reactions for each drug used, to assess the frequency of IgE-mediated reactions in even mild reactions, and to compare the degree of agreement between anesthesiologist suspicion and allergy diagnosis. METHODS: We included patients diagnosed with a clinical hypersensitivity reaction during a procedure under general anesthesia over a 30-month period (February 2008 to August 2010). Plasma histamine and serum tryptase concentrations were determined in these patients. We performed skin tests to diagnose the causative agent. Data from the hospital electronic prescribing system were collected to determine the ratio of reactions for each drug. RESULTS: During the study period, 16,946 anesthetic procedures were performed (53% involved males; mean age, 51.6 years). Forty-four perianesthetic reactions were recorded, and the ratio of reactions was 1 in 385 operations (95% confidence interval, 1/529-1/287). Twenty-five reactions (25/44; 57%) occurred during the induction of anesthesia. Twenty-one reactions (21/44; 48%) were mild, involving only skin, and 23 of 44 (52%) were anaphylactic reactions. Four of 10 patients who had only a rash experienced IgE-mediated reactions. Five surgeries (11%) were suspended because of the severity of the reactions. Fifteen reactions (15/30; 50%) were IgE mediated, and, in 2 of 30 (7%), a non-IgE agent was found (cold urticaria and nonsteroidal anti-inflammatory drug intolerance). The ratio of reactions for each drug was as follows: protamine, 1 in 468; cisatracurium, 1 in 1388; amoxicillin-clavulanate, 1 in 1968; atracurium, 1 in 2039; and dipyrone, 1 in 3159. CONCLUSIONS: Perioperative reactions are more common than previously reported. Mild hypersensitivity perioperative reactions-involving only skin-should be considered in evaluating patients because a substantial number of these reactions are IgE mediated.

Comparative effects of gastric bypass and sleeve gastrectomy on plasma osteopontin concentrations in humans.

BACKGROUND: Bariatric surgery (BS) has proven to be an effective treatment for morbid obesity. Osteopontin (OPN) is a proinflammatory cytokine involved in the development of obesity. The aim of our study was to determine the effect of weight loss following BS on circulating levels of OPN in humans. METHODS: Body composition and circulating concentrations of OPN and markers of bone metabolism were determined in obese patients who underwent Roux-en-Y gastric bypass (RYGB; n = 40) or sleeve gastrectomy (SG; n = 11). RESULTS: Patients who underwent RYGB or SG showed decreased body weight (P < 0.001) and body fat percentage (P < 0.001) as well as lower insulin resistance. However, plasma OPN levels were significantly increased after RYGB (P < 0.001) but remained unchanged following SG (P = 0.152). Patients who underwent RYGB also showed significantly increased C-terminal telopeptide of type-I collagen (ICTP) (P < 0.01) and osteocalcin (P < 0.001) while bone mineral density tended to decrease (P = 0.086). Moreover, OPN concentrations were positively correlated with the bone resorption marker ICTP after surgery. On the other hand, patients who underwent SG showed significantly increased ICTP levels (P < 0.05), and the change in OPN was positively correlated with the change in ICTP and negatively with the change in vitamin D after surgery (P < 0.05). CONCLUSIONS: RYGB increased circulating OPN levels, while they remained unaltered after SG. The increase in OPN levels after RYGB could be related to the increased bone resorption in relation to its well-known effects on bone of this malabsorptive procedure in comparison to the merely restrictive SG.

Single anastomosis duodeno-ileal bypass with sleeve gastrectomy generates sustained improvement of glycemic control compared with sleeve gastrectomy in the diet-induced obese rat model.

Bariatric surgery has become a recognized and effective procedure for treating obesity and type 2 diabetes (T2D). Our objective was to directly compare the caloric intake-independent effects of sleeve gastrectomy (SG) and single anastomosis duodenoileal bypass with SG (SADI-S) on glucose tolerance in rats with diet-induced obesity (DIO) and to elucidate the differences between bariatric surgery and caloric restriction.A total of 120 adult male Wistar rats with DIO and insulin resistance were randomly assigned to surgical (sham operation, SG, and SADI-S) and dietary (pair-feeding the amount of food eaten by animals undergoing the SG or SADI-S surgeries) interventions. Body weight and food intake were weekly monitored, and 6 weeks after interventions, fasting plasma glucose, oral glucose and insulin tolerance tests, plasma insulin, adiponectin, GIP, GLP-1, and ghrelin levels were determined.The body weight of SADI-S rats was significantly (p < 0.001) lower as compared to the sham-operated, SG, and pair-fed groups. Furthermore, SADI-S rats exhibited decreased whole body fat mass (p < 0.001), lower food efficiency rates (p < 0.001), and increased insulin sensitivity, as well as improved glucose and lipid metabolism compared to that of the SG and pair-fed rats.SADI-S was more effective than SG, or caloric restriction, in improving glycemic control and metabolic profile, with a higher remission of insulin resistance as well as long-term weight loss.

FNDC4 reduces hepatocyte inflammatory cell death via AMPKα in metabolic dysfunction-associated steatotic liver disease.

BACKGROUND: The molecular mediators responsible for the progression of metabolic dysfunction-associated steatotic liver disease (MASLD) to steatohepatitis (MASH) have not yet been completely disentangled. We sought to analyze whether FNDC4, an hepatokine and adipokine with anti-inflammatory properties, is involved in TNF-α-induced inflammatory cell death in patients with MASLD. METHODS: Plasma FNDC4 (n = 168) and hepatic FNDC4 and inflammatory cell death (n = 65) were measured in samples from patients with severe obesity with available liver biopsy-proven MASLD diagnosis. The effect of FNDC4 on TNF-α-induced pyroptosis, apoptosis and necroptosis (PANoptosis) and mitochondrial dysfunction was studied in vitro using human HepG2 hepatocytes. RESULTS: Compared with individuals with normal liver, patients with type 2 diabetes and MASLD exhibited decreased hepatic FNDC4 mRNA and protein levels, which were related to liver inflammation. An overexpression of TNF-α, its receptor TNF-R1 and factors involved in inflammatory cell death was also found in the liver of these patients. FNDC4-knockdown in HepG2 hepatocytes increased apoptotic cell death, while FNDC4 treatment blunted NLRP3 inflammasome-induced pyroptosis, apoptosis and necroptosis in TNF-α-stimulated hepatocytes. Moreover, FNDC4 improved TNF-α-induced hepatocyte mitochondrial dysfunction by enhancing mitochondrial DNA (mtDNA) copy number and OXPHOS complex subunits I, II, III and V protein expression. Mechanistically, AMP-activated protein kinase α (AMPKα) was required for the FNDC4-mediated inhibition of cell death and increase in mtDNA content. CONCLUSIONS: FNDC4 acts as a hepatocyte survival factor favouring mitochondrial homeostasis and decreasing inflammatory cell death via AMPKα. Collectively, our study identifies FNDC4 as an attractive target to prevent hepatocellular damage in patients with MASLD.

Corrigendum: Increased levels of interleukin-36 in obesity and type 2 diabetes fuels adipose tissue inflammation by inducing its own expression and release by adipocytes and macrophages.

[This corrects the article DOI: 10.3389/fimmu.2022.832185.].

Uroguanylin prevents hepatic steatosis, mitochondrial dysfunction and fibrosis in obesity-associated NAFLD.

BACKGROUND: The biological mediators supporting the resolution of liver steatosis, inflammation and fibrosis after bariatric surgery in patients with obesity and NAFLD remain unclear. We sought to analyze whether uroguanylin and guanylin, two gut hormones involved in the regulation of satiety, food preference and adiposity, are involved in the amelioration of obesity-associated NAFLD after bariatric surgery. METHODS: Proguanylin (GUCA2A) and prouroguanylin (GUCA2B) were measured in 214 participants undergoing bariatric surgery with biopsy-proven NAFLD diagnosis. Pathways involved in lipid metabolism, mitochondrial network and fibrogenesis were evaluated in liver biopsies (n = 137). The effect of guanylin and uroguanylin on these metabolic functions was assessed in HepG2 hepatocytes and LX-2 hepatic stellate cells (HSC) under lipotoxic and profibrogenic conditions. RESULTS: Plasma and hepatic expression of GUCA2B were decreased in obesity-associated NAFLD. Both GUCA2A and GUCA2B levels were increased after sleeve gastrectomy and Roux-en-Y gastric bypass in parallel to the improved liver function. The liver of patients with type 2 diabetes showed impaired mitochondrial ß-oxidation, biogenesis, dynamics as well as increased fibrosis. Uroguanylin diminished the lipotoxicity in palmitate-treated HepG2 hepatocytes, evidenced by decresased steatosis and lipogenic factors, as well as increased mitochondrial network expression, AMPK-induced ß-oxidation and oxygen consumption rate. Additionally, uroguanylin, but not guanylin, reversed HSC myofibroblast transdifferentiation as well as fibrogenesis after TGF-ß1 stimulation. CONCLUSIONS: Uroguanylin constitutes a protective factor against lipotoxicity, mitochondrial dysfunction and fibrosis. Increased GUCA2B levels might contribute to improve liver injury in patients with obesity-associated NAFLD after bariatric surgery.

Increased Expression Levels of Netrin-1 in Visceral Adipose Tissue during Obesity Favour Colon Cancer Cell Migration.

Netrin (NTN)-1, an extracellular matrix protein with a crucial role in inflammation, is dysregulated during obesity (OB) and influences colon cancer (CC) progression. To decipher the mechanisms underlying CC development during obesity, we examined the expression of NTN1 and its receptors in the visceral adipose tissue (VAT) of 74 (25 normal weight (NW)) (16 with CC) and 49 patients with OB (12 with CC). We also evaluated the effect of caloric restriction (CR) on the gene expression levels of Ntn1 and its receptors in the colon from a rat model fed a normal diet. The impact of adipocyte-conditioned media (ACM) from patients with OB and NTN-1 was assessed on the expression levels of neogenin 1(NEO1), deleted in colorectal carcinomas (DCC) and uncoordinated-5 homolog B (UNC5B) in Caco-2 and HT-29 human colorectal cell lines, as well as on Caco-2 cell migration. Increased NTN1 and NEO1 mRNA levels in VAT were due to OB (p < 0.05) and CC (p < 0.001). In addition, an upregulation in the expression levels of DCC and UNC5B in patients with CC (p < 0.01 and p < 0.05, respectively) was observed. Decreased (p < 0.01) Ntn1 levels in the colon from rats submitted to CR were found. In vitro experiments showed that ACM increased DCC (p < 0.05) and NEO1 (p < 0.01) mRNA levels in HT-29 and Caco-2 cell lines, respectively, while UNC5B decreased (p < 0.01) in HT-29. The treatment with NTN-1 increased (p < 0.05) NEO1 mRNA levels in HT-29 cells and DCC (p < 0.05) in both cell lines. Finally, we revealed a potent migratory effect of ACM and NTN-1 on Caco-2 cells. Collectively, these findings point to increased NTN-1 during OB and CC fuelling cancer progression and exerting a strong migratory effect on colon cancer cells.

Antagonic effect of ghrelin and LEAP-2 on hepatic stellate cell activation and liver fibrosis in obesity-associated nonalcoholic fatty liver disease.

BACKGROUND: Growing evidence suggests the key role of ghrelin in the onset and progression of nonalcoholic fatty liver disease (NAFLD). The potential participation of ghrelin and the ghrelin receptor antagonist, LEAP-2, in the onset of liver fibrosis in patients with severe obesity and NAFLD through the regulation of TGF-ß1-induced hepatic stellate cell (HSC) activation was investigated. METHODS: Circulating (n = 179) and hepatic expression (n = 95) of ghrelin and LEAP-2 were measured in patients with severe obesity and available liver pathology analysis undergoing Roux-en-Y gastric bypass (RYGB). The effect of ghrelin isoforms and LEAP-2 on TGF-ß1-induced HSC activation, fibrogenic response, and contractile properties was evaluated in vitro in human LX-2 cells. RESULTS: Plasma and hepatic ghrelin were negatively associated, while LEAP-2 exhibited a positive association with liver fibrosis in patients with obesity and NAFLD. Six months after RYGB, hepatic function was improved and, although acylated ghrelin and LEAP-2 concentrations remained unchanged, both hormones were inversely related to post-surgical levels of profibrogenic factors TGF-ß1 and TIMP-1. Acylated ghrelin treatment reversed TGF-ß1-induced myofibroblast-like phenotype, collagen contractile properties, and the upregulation of factors involved in HSC activation and fibrogenesis via PI3K/Akt/mTOR pathway. Moreover, acylated ghrelin inhibited the mild HSC activation induced by LEAP-2. CONCLUSIONS: Ghrelin is an anti-fibrogenic factor blocking HSC activation induced by the most potent fibrogenic cytokine, TGF-ß1, and LEAP-2. The imbalance between acylated ghrelin and ghrelin receptor antagonist LEAP-2 might contribute to maintain liver fibrosis in patients with obesity and NAFLD.

Effect of guanylin peptides on pancreas steatosis and function in experimental diet-induced obesity and after bariatric surgery.

Introduction: Obesity contributes to ectopic fat deposition in non-adipose organs, including the pancreas. Pancreas steatosis associates with inflammation and ß-cell dysfunction, contributing to the onset of insulin resistance and type 2 diabetes. An improvement of pancreatic steatosis and indices of insulin resistance is observed following bariatric surgery, but the underlying mechanisms remain unknown. We sought to analyze whether guanylin (GUCA2A) and uroguanylin (GUCA2B), two gut hormones involved in the regulation of satiety, food preference and adiposity, are involved in the amelioration of pancreas fat accumulation after bariatric surgery. Methods: Pancreas steatosis, inflammation, islet number and area were measured in male Wistar rats with diet-induced obesity (n=125) subjected to surgical (sham operation and sleeve gastrectomy) or dietary (pair-fed to the amount of food eaten by gastrectomized animals) interventions. The tissue distribution of guanylate cyclase C (GUCY2C) and the expression of the guanylin system were evaluated in rat pancreata by real-time PCR, Western-blot and immunohistochemistry. The effect of guanylin and uroguanylin on factors involved in insulin secretion and lipogenesis was determined in vitro in RIN-m5F ß-cells exposed to lipotoxic conditions. Results: Sleeve gastrectomy reduced pancreas steatosis and inflammation and improved insulin sensitivity and synthesis. An upregulation of GUCA2A and GUCY2C, but not GUCA2B, was observed in pancreata from rats with diet-induced obesity one month after sleeve gastrectomy. Interestingly, both guanylin and uroguanylin diminished the lipotoxicity in palmitate-treated RIN-m5F ß-cells, evidenced by lower steatosis and downregulated lipogenic factors Srebf1, Mogat2 and Dgat1. Both guanylin peptides reduced insulin synthesis (Ins1 and Ins2) and release from RIN-m5F ß-cells, but only guanylin upregulated Wnt4, a factor that controls ß-cell proliferation and function. Discussion: Together, sleeve gastrectomy reduced pancreatic steatosis and improved ß-cell function. Several mechanisms, including the modulation of inflammation and lipogenesis as well as the upregulation of GUCA2A in the pancreas, might explain this beneficial effect of bariatric surgery.