Short Bowel Syndrome: A Paradigm for Intestinal Adaptation to Nutrition?

Short bowel syndrome (SBS) is a rare disease that results from extensive resection of the intestine. When the remaining absorption surface of the intestine cannot absorb enough macronutrients, micronutrients, and water, SBS results in intestinal failure (IF). Patients with SBS who suffer from IF require parenteral nutrition for survival, but long-term parenteral nutrition may lead to complications such as catheter sepsis and metabolic diseases. Spontaneous intestinal adaptation occurs weeks to months after resection, resulting in hyperplasia of the remnant gut, modification of gut hormone levels, dysbiosis, and hyperphagia. Oral nutrition and presence of the colon are two major positive drivers for this adaptation. This review aims to summarize the current knowledge of the mechanisms underlying spontaneous intestinal adaptation, particularly in response to modifications of luminal content, including nutrients. In the future, dietary manipulations could be used to treat SBS.

Neuromedin U is a gut peptide that alters oral glucose tolerance by delaying gastric emptying via direct contraction of the pylorus and vagal-dependent mechanisms.

The gut-brain peptide neuromedin U (NMU) decreases food intake and body weight and improves glucose tolerance. Here, we characterized NMU as an enteropeptide and determined how it impacts glucose excursion. NMU was expressed predominantly in the proximal small intestine, and its secretion was triggered by ingestion of a mixed meal. Although a single peripheral injection of NMU in C57BL/6NRj mice prevented the rise of glycemia upon an oral but not an intraperitoneal load of glucose, it unexpectedly prevented insulin secretion, only slightly improved peripheral insulin sensitivity, and barely reduced intestinal glucose absorption. Interestingly, peripheral administration of NMU abrogated gastric emptying. NMU receptors 1 and 2 were detected in pyloric muscles and NMU was able to directly induce pyloric contraction in a dose-dependent manner ex vivo in isometric chambers. Using a modified glucose tolerance test, we demonstrate that improvement of oral glucose tolerance by NMU was essentially, if not exclusively, because of its impact on gastric emptying. Part of this effect was abolished in vagotomized (VagoX) mice, suggesting implication of the vagus tone. Accordingly, peripheral injection of NMU was associated with increased number of c-FOS-positive neurons in the nucleus of the solitary tract, which was partly prevented in VagoX mice. Finally, NMU kept its ability to improve oral glucose tolerance in obese and diabetic murine models. Together, these data demonstrate that NMU is an enteropeptide that prevents gastric emptying directly by triggering pylorus contraction and indirectly through vagal afferent neurons. This blockade consequently reduces intestinal nutrient absorption and thereby results in an apparent improved tolerance to oral glucose challenge.-Jarry, A.-C., Merah, N., Cisse, F., Cayetanot, F., Fiamma, M.-N., Willemetz, A., Gueddouri, D., Barka, B., Valet, P., Guilmeau, S., Bado, A., Le Beyec, J., Bodineau, L., Le Gall, M. Neuromedin U is a gut peptide that alters oral glucose tolerance by delaying gastric emptying via direct contraction of the pylorus and vagal-dependent mechanisms.

Intestinal deletion of leptin signaling alters activity of nutrient transporters and delayed the onset of obesity in mice.

The importance of B-isoform of leptin receptor (LEPR-B) signaling in the hypothalamus, pancreas, or liver has been well characterized, but in the intestine, a unique site of entry for dietary nutrition into the body, it has been relatively ignored. To address this question, we characterized a mouse model deficient for LEPR-B specifically in intestinal epithelial cells (IECs). (IEC)LEPR-B-knockout (KO) and wild-type (WT) mice were generated by Cre-Lox strategy and fed a normal or high-fat diet (HFD). The analyses of the animals involved histology and immunohistochemistry of intestinal mucosa, indirect calorimetric measurements, whole-body composition, and expression and activities of nutrient transporters. (IEC)LEPR-B-KO mice exhibited a 2-fold increase in length of jejunal villi and have normal growth on a normal diet but were less susceptible (P<0.01) to HFD-induced obesity. No differences occurred in energy intake and expenditure between (IEC)LEPR-B-WT and -KO mice, but (IEC)LEPR-B-KO mice fed an HFD showed increased excreted fats (P<0.05). Activities of the Na(+)/glucose cotransporter SGLT-1 and GLUT2 were unaffected in LEPR-B-KO jejunum, while GLUT5-mediated fructose transport and PepT1-mediated peptide transport were substantially reduced (P<0.01). These data demonstrate that intestinal LEPR-B signaling is important for the onset of diet-induced obesity. They suggest that intestinal LEPR-B could be a potential per os target for prevention against obesity.

Circulating Apolipoprotein B-48 as a Biomarker of Parenteral Nutrition Dependence in Adult Patients with Short Bowel Syndrome.

Short bowel syndrome (SBS) is a rare but serious condition that may lead to chronic intestinal failure. Citrulline concentrations are currently used to reflect the residual intestinal mass in patients with SBS, although this method has several limitations. In a cohort of patients with SBS, we quantified apolipoprotein B-48 (ApoB-48), which is exclusively synthesized by enterocytes and secreted associated with dietary lipids and investigated the relationship between ApoB-48 and clinical and biological data as well as PN dependence. A total of 51 adult patients were included, 36 of whom were PN-dependent. We found a robust positive correlation between circulating ApoB-48 and residual small bowel length, which was also found in the subgroup of patients with jejunocolic anastomosis. Fasting ApoB-48 levels were significantly lower in PN-dependent patients than in PN-weaned patients and negatively correlated with parenteral nutrition dependence. Our results suggest that ApoB-48 could be proposed as a marker of intestinal absorptive function and could be an interesting follow-up marker in patients with SBS.

Hyperphagia is prominent in adult patients with short bowel syndrome: A role for the colon?

RATIONALE: Short Bowel Syndrome (SBS) is the major cause of chronic intestinal failure (IF) and requires parenteral nutrition (PN). After bowel resection, some patients develop spontaneous intestinal adaptations and hyperphagia. Since promoting oral energy intake contributes to PN weaning, this study aims to characterize hyperphagia in patients with SBS and identify its determinants. METHODS: This observational retrospective study included adult patients with SBS who were followed at an expert PN center between 2006 and 2019, with at least 2 separate nutritional assessments. Exclusion criteria were: active neoplasia, alternative treatment for IF or appetite-affecting medication. Resting energy expenditure (REE) was calculated for each patient using the Harris-Benedict equation. Food Intake Ratio (FIR) was calculated by dividing the highest caloric oral intake by REE and hyperphagia was defined as FIR >1.5. RESULTS: Among the 59 patients with SBS included in this study, 82.6% had a FIR >1.5, including 15.5% with a FIR >3. Protein supplied approximately 16% of total energy intake while fat and carbohydrates provided 36% and 48%, respectively. The FIR was independent of gender and whether patients received oral nutrition alone (n = 28) or combined with PN (n = 31). The FIR was also not associated with residual small bowel length, nor the proportion of preserved colon. However, it was negatively correlated with the body mass index (BMI) of these patients (r = -0.533, p < 0.001), whether they had PN support or not. Patients with either a jejuno-colonic (n = 31) or a jejuno-ileal anastomosis (n = 9), had a significantly higher FIR compared to those with an end-jejunostomy (n = 18) (p < 0.05). However, no difference was found in the proportion of calories provided by protein, fat and carbohydrate between the 3 patients groups divided according to the SBS anatomical type. CONCLUSION: A large majority of patients with SBS exhibited a hyperphagia regardless of PN dependence or bowel length, which was inversely correlated with BMI. The presence of the colon in continuity, thus in contact with the nutritional flow, seems to favor a higher oral intake which is beneficial for the nutritional autonomy of patients. This raises the question of a role of colonic microbiota and hormones in this behavior. Finally, this study also revealed an unexpected discrepancy between recommended energy intakes from protein, fat and carbohydrate and the actual intake of patients with SBS.

Fecal microbiota transplantation in a rodent model of short bowel syndrome: A therapeutic approach?

Extensive intestinal resection leads to Short Bowel Syndrome (SBS), the main cause of chronic intestinal failure. Colon preservation is crucial for spontaneous adaptation, to improve absorption and reduce parenteral nutrition dependence. Fecal microbiota transplantation (FMT), a promising approach in pathologies with dysbiosis as the one observed in SBS patients, was assessed in SBS rats with jejuno-colonic anastomosis. The evolution of weight and food intake, the lenght of intestinal villi and crypts and the composition of fecal microbiota of Sham and SBS rats, transplanted or not with high fat diet rat microbiota, were analyzed. All SBS rats lost weight, increased their food intake and exhibited jejunal and colonic hyperplasia. Microbiota composition of SBS rats, transplanted or not, was largely enriched with Lactobacillaceae, and α- and ß-diversity were significantly different from Sham. The FMT altered microbiota composition and α- and ß-diversity in Sham but not SBS rats. FMT from high fat diet rats was successfully engrafted in Sham, but failed to take hold in SBS rats, probably because of the specific luminal environment in colon of SBS subjects favoring aero-tolerant over anaerobic bacteria. Finally, the level of food intake in SBS rats was positively correlated with their Lactobacillaceae abundance. Microbiota transfer must be optimized and adapted to this specific SBS environment.

Shortening the Biliopancreatic Limb Length of One Anastomosis Gastric Bypass Maintains Glucose Homeostasis Improvement with Limited Weight Loss.

One anastomosis gastric bypass (OAGB) is associated with similar metabolic improvements and weight loss as Roux-en-Y gastric bypass (RYGB). However, this bariatric procedure is still controversial as it is suspected to result in undernutrition. Reducing the size of the biliopancreatic limb of OAGB could be essential to maintain positive outcomes while preventing side effects. The objective of this study was to compare and contrast outcomes of OAGB with two different biliopancreatic limb lengths to RYGB and Sham surgery in obese and non-obese rats. Lean and diet-induced obese Wistar rats were operated on RYGB, OAGB with a short (15 cm OAGB-15) or a long (35 cm OAGB-35) biliopancreatic limb or Sham surgery. Body weight and food intake were monitored over 30 weeks, and rats underwent oral glucose and insulin tolerance tests with a pancreatic and gut hormone secretion assay. Macronutrient absorption was determined by fecal analyses. Statistical analyses used non-parametric one-way or two-way ANOVA tests. Compared to Sham rats, RYGB, OAGB-15 and OAGB-35 rats displayed a significant reduced weight. Weight loss was greater after OAGB-35 than after OAGB-15 or Sham surgery because of transient malabsorption. All OAGB- and RYGB-operated rats displayed an improved pancreatic and gut hormone secretion in response to a meal compared to Sham rats, these effects were independent of limb length, rat weight, and maintained overtime. In conclusion, glucose homeostasis was similarly improved in obese and non-obese OAGB-15 and OAGB-35 rats suggesting that shortening the biliopancreatic limb can improve the metabolic parameters without a major influence on weight.

Similar Gut Hormone Secretions Two Years After One Anastomosis Gastric Bypass and Roux-en-Y Gastric Bypass: a Pilot Study.

OBJECTIVES: One-anastomosis gastric bypass (OAGB) is as effective as Roux-en-Y gastric bypass (RYGB) regarding weight loss and diabetes remission. However, there are no data on gut hormone secretions after OAGB. The aim of this study was to compare fasting and postprandial secretions of gut and pancreatic hormones in OAGB versus RYGB patients. DESIGN AND METHODS: Twenty-nine patients, 16 OAGB- and 13 RYGB-operated, underwent a liquid mixed-meal tolerance test at 2 years' post-surgery. Blood was sampled before and 15, 30, 60, 90, and 120 min after meal for plasma measurement of glucose, C-peptide, insulin, glucagon, GLP-1, GIP, GLP-2, PYY, and ghrelin. RESULTS: Percentage of total weight loss 2 years post-surgery were -33.9 ± 1.8% for OAGB and -31.2 ± 1.6% for RYGB (p = 0.6). Four patients with persistent diabetes were excluded for further analysis. Fasting and postprandial glucose levels (peaks and area under curve values) were similar between groups. HOMA index was lower in the OAGB group (0.8 ± 0.1 vs 1.3 ± 0.2 in RYGB, p < 0.05). Levels of C-peptide (or insulin) measured at 30 min were significantly lower in OAGB vs RYGB patients (6.9 ± 0.5 vs 9.7 ± 1.1 µg/l, p < 0.05). No difference was observed between OAGB and RYGB groups for GLP-1, GLP-2, PYY, or ghrelin postprandial secretions, but GIP tended to be lower in OAGB vs RYGB patients (756 ± 155 vs 1100 ± 188 pg/ml for postprandial peak concentrations, p = 0.06). CONCLUSIONS: This is the first clinical study showing that OAGB procedure, like RYGB, results in high postprandial secretions of gut hormones, in particular GLP-1. TRIAL REGISTRATION: Clinical Trials NCT03482895.

Bariatric surgery induces a new gastric mucosa phenotype with increased functional glucagon-like peptide-1 expressing cells.

Glucagon-Like Peptide-1 (GLP-1) undergoes rapid inactivation by dipeptidyl peptidase-4 (DPP4) suggesting that target receptors may be activated by locally produced GLP-1. Here we describe GLP-1 positive cells in the rat and human stomach and found these cells co-expressing ghrelin or somatostatin and able to secrete active GLP-1 in the rats. In lean rats, a gastric load of glucose induces a rapid and parallel rise in GLP-1 levels in both the gastric and the portal veins. This rise in portal GLP-1 levels was abrogated in HFD obese rats but restored after vertical sleeve gastrectomy (VSG) surgery. Finally, obese rats and individuals operated on Roux-en-Y gastric bypass and SG display a new gastric mucosa phenotype with hyperplasia of the mucus neck cells concomitant with increased density of GLP-1 positive cells. This report brings to light the contribution of gastric GLP-1 expressing cells that undergo plasticity changes after bariatric surgeries, to circulating GLP-1 levels.

Intestinal plasticity in response to nutrition and gastrointestinal surgery.

The plasticity of a material corresponds to its capacity to change its feature under the effect of an external action. Intestinal plasticity could be defined as the ability of the intestine to modify its size or thickness and intestinal cells to modulate their absorption and secretion functions in response to external or internal cues/signals. This review will focus on intestinal adaptation mechanisms in response to diet and nutritional status. These physiological mechanisms allow a fine and rapid adaptation of the gut to promote absorption of ingested food, but they can also lead to obesity in response to overnutrition. This plasticity could thus become a therapeutic target to treat not only undernutrition but also obesity. How the intestine adapts in response to 2 types of surgical remodeling of the digestive tract-extensive bowel resection leading to intestinal failure and surgical treatment of pathological obesity (ie, bariatric surgeries)-will also be reviewed.

Fasting levels of glicentin are higher in Roux-en-Y gastric bypass patients exhibiting postprandial hypoglycemia during a meal test.

BACKGROUND: Post-bypass postprandial hypoglycemia (PPH) is a frequent complication of Roux-en-Y Gastric Bypass (RYGB) but predictors remain poorly identified and are needed to assess individual risk. After RYGB, exaggerated secretion of glucagon-like peptide-1 (GLP-1) and insulin could lead to PPH, but other proglucagon-derived peptides, including glicentin and glucagon, could also contribute to this phenomenon. OBJECTIVES: To identify biological hypoglycemia in relation to the secretion of proglucagon-derived peptides during a mixed-meal test (MMT) in RYGB patients. SETTING: University hospital. METHODS: Twenty RYGB patients reporting symptoms consistent with PPH were examined 36.9 ± 5.1 months after surgery. Plasma levels of glucose, c-peptide, glucagon, GLP-1 and glicentin were assessed before and during MMT. Patients with postprandial hypoglycemia ≤3 mM (54 mg/dL) during MMT were assigned to HYPO group and compared with patients not exhibiting hypoglycemia (NONHYPO group). RESULTS: Seven patients displayed hypoglycemia ≤3 mM (HYPO) during the MMT. Lower fasting glycemia (4.5 mM versus 5.3 mM, P<.05) and higher fasting glicentin (22.6 pM versus 14.0 pM, P<.05) were observed in HYPO versus NONHYPO patients. Fasting glicentin was inversely correlated with postprandial nadir glucose. Examining the receiver-operating characteristics curve analysis, a cutoff of 17.2 pM for fasting glicentin identified PPH with 85.7% sensitivity and 53.8% specificity. All patients exhibited a similar increase of postprandial GLP-1, glucagon, and glicentin secretions that correlated with each other. CONCLUSIONS: These results suggest that fasting glicentin is a potential biomarker to examine in operated-obese patients at risk of developing PPH. Further studies are needed before proposing fasting glicentin as a predictive factor of PPH.

Homozygous null mutation of the melanocortin-4 receptor and severe early-onset obesity.

OBJECTIVE: To describe the clinical and biological phenotype of a child who is severely obese and is homozygous for a new melanocortin-4 receptor (MC4R) gene mutation leading to a truncated receptor. STUDY DESIGN: Direct sequencing of the MC4R gene was performed in a child who was severely obese and his relatives. Phenotypic characterization included weight evolution, anthropometric parameters, and endocrine and metabolic complications. Growth curves were compared with those of children carrying leptin receptor (LEPR) homozygous mutation, MC4R heterozygous mutations, and MC4R wild type allele. RESULTS: We found a homozygous 2-base pair deletion (del 346-347AG) leading to a stop codon. This new mutation leads to a truncated MC4R after the second transmembrane domain in a 3-year-old boy with severe early-onset obesity. Segregation analysis of the mutation showed that the 2 parents and 2 adult relatives were heterozygous carriers for the mutation. Heterozygous carriers displayed an obese phenotype, but with a variable degree of severity. The homozygous carrier of the mutation was hyperphagic and showed a rapid increase in weight in the very first months of life. His weight evolution closely resembled that of patients who are LEPR deficient, but markedly differed with that of children carrying either heterozygous MC4R mutations or MC4R wild type allele. No other hormonal or metabolic anomaly was found in the child. CONCLUSIONS: This phenotype of a boy carrying a new homozygous MC4R mutation confirms the critical role of MC4R in the early dynamic of weight gain and phenotypic differences with heterozygous carriers.

Microbiota Is Involved in Post-resection Adaptation in Humans with Short Bowel Syndrome.

Short bowel syndrome (SBS) is characterized by severe intestinal malabsorption following restrictive surgery. The objective of this study was to determine the functional contribution of SBS-microbiota after resection. It is well-known that SBS-microbiota displayed specific features with a prevalence of Lactobacillus, a low amount of some anaerobic microbes (Clostridium leptum) and an accumulation of fecal lactate in some patients. Patients with jejuno-colonic anastomosis were stratified according to the presence of lactate in their feces and, we observe that the lactate-producing bacteria were predominant in the sub-group of patients accumulating fecal lactate. One case of D-encephalopathy crisis occurred when the D-lactate isoform accumulated in the feces and plasma bicarbonate levels decreased. The fecal sample at the time of the encephalopathy was transferred to germ free rats (SBS-H rats). The SBS-H microbiota conserved some characteristics of the SBS donnor, predominated by lactate-producing bacteria (mainly Lactobacillus), a low level of lactate-consuming bacteria and undetectable C. leptum. However, lactate did not accumulate in feces of recipient rats and the D-encephalopathy was not reproduced in SBS-H rats. This suggests that the intact small bowel of the recipient rats protected them from lactate accumulation and that D-lactate encephalopathy can occur only in the absence of small intestine. After fecal transfer, we also show that gnotobiotic rats exhibited high levels of circulating GLP-1 and ghrelin, two hormones that are known to be induced in SBS patients. Therefore, the microbiota of SBS is a reservoir of biological signals involved in post-resection adaptation.

Evaluation of a melanocortin-4 receptor (MC4R) agonist (Setmelanotide) in MC4R deficiency.

OBJECTIVE: Pro-opiomelanocortin (POMC)-derived peptides act on neurons expressing the Melanocortin 4 receptor (MC4R) to reduce body weight. Setmelanotide is a highly potent MC4R agonist that leads to weight loss in diet-induced obese animals and in obese individuals with complete POMC deficiency. While POMC deficiency is very rare, 1-5% of severely obese individuals harbor heterozygous mutations in MC4R. We sought to assess the efficacy of Setmelanotide in human MC4R deficiency. METHODS: We studied the effects of Setmelanotide on mutant MC4Rs in cells and the weight loss response to Setmelanotide administration in rodent studies and a human clinical trial. We annotated the functional status of 369 published MC4R variants. RESULTS: In cells, we showed that Setmelanotide is significantly more potent at MC4R than the endogenous ligand alpha-melanocyte stimulating hormone and can disproportionally rescue signaling by a subset of severely impaired MC4R mutants. Wild-type rodents appear more sensitive to Setmelanotide when compared to MC4R heterozygous deficient mice, while MC4R knockout mice fail to respond. In a 28-day Phase 1b clinical trial, Setmelanotide led to weight loss in obese MC4R variant carriers. Patients with POMC defects upstream of MC4R show significantly more weight loss with Setmelanotide than MC4R deficient patients or obese controls. CONCLUSIONS: Setmelanotide led to weight loss in obese people with MC4R deficiency; however, further studies are justified to establish whether Setmelanotide can elicit clinically meaningful weight loss in a subset of the MC4R deficient obese population.

Extensive Intestinal Resection Triggers Behavioral Adaptation, Intestinal Remodeling and Microbiota Transition in Short Bowel Syndrome.

Extensive resection of small bowel often leads to short bowel syndrome (SBS). SBS patients develop clinical mal-absorption and dehydration relative to the reduction of absorptive area, acceleration of gastrointestinal transit time and modifications of the gastrointestinal intra-luminal environment. As a consequence of severe mal-absorption, patients require parenteral nutrition (PN). In adults, the overall adaptation following intestinal resection includes spontaneous and complex compensatory processes such as hyperphagia, mucosal remodeling of the remaining part of the intestine and major modifications of the microbiota. SBS patients, with colon in continuity, harbor a specific fecal microbiota that we called "lactobiota" because it is enriched in the Lactobacillus/Leuconostoc group and depleted in anaerobic micro-organisms (especially Clostridium and Bacteroides). In some patients, the lactobiota-driven fermentative activities lead to an accumulation of fecal d/l-lactates and an increased risk of d-encephalopathy. Better knowledge of clinical parameters and lactobiota characteristics has made it possible to stratify patients and define group at risk for d-encephalopathy crises.

Enhanced Ghrelin Levels and Hypothalamic Orexigenic AgRP and NPY Neuropeptide Expression in Models of Jejuno-Colonic Short Bowel Syndrome.

Short bowel syndrome (SBS) patients developing hyperphagia have a better outcome. Gastrointestinal endocrine adaptations help to improve intestinal functions and food behaviour. We investigated neuroendocrine adaptations in SBS patients and rat models with jejuno-ileal (IR-JI) or jejuno-colonic (IR-JC) anastomosis with and without parenteral nutrition. Circulating levels of ghrelin, PYY, GLP-1, and GLP-2 were determined in SBS rat models and patients. Levels of mRNA for proglucagon, PYY and for hypothalamic neuropeptides were quantified by qRT-PCR in SBS rat models. Histology and immunostaining for Ki67, GLP-1 and PYY were performed in SBS rats. IR-JC rats, but not IR-JI, exhibited significantly higher crypt depths and number of Ki67-positive cells than sham. Fasting and/or postprandial plasma ghrelin and PYY concentrations were higher, or tend to be higher, in IR-JC rats and SBS-JC patients than in controls. Proglucagon and Pyy mRNA levels were significantly enhanced in IR-JC rats. Levels of mRNA coding hypothalamic orexigenic NPY and AgRP peptides were significantly higher in IR-JC than in sham rats. We demonstrate an increase of plasma ghrelin concentrations, major changes in hypothalamic neuropeptides levels and greater induction of PYY in SBS-JC rats and patients suggesting that jejuno-colonic continuity creates a peculiar environment promoting further gut-brain adaptations.

Remodeling of the residual gastric mucosa after roux-en-y gastric bypass or vertical sleeve gastrectomy in diet-induced obese rats.

Whereas the remodeling of intestinal mucosa after bariatric surgeries has been the matter of numerous studies to our knowledge, very few reported on the remodeling of the residual gastric mucosa. In this study, we analyzed remodeling of gastric mucosa after Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG) in rats. Diet-induced obese rats were subjected to RYGB, VSG or sham surgical procedures. All animals were assessed for food intake, body-weight, fasting blood, metabolites and hormones profiling, as well as insulin and glucose tolerance tests before and up to 5 weeks post-surgery. Remodeling of gastric tissues was analyzed by routine histology and immunohistochemistry studies, and qRT-PCR analyses of ghrelin and gastrin mRNA levels. In obese rats with impaired glucose tolerance, VSG and RYGB caused substantial weight loss and rats greatly improved their oral glucose tolerance. The remaining gastric mucosa after VSG and gastric pouch (GP) after RYGB revealed a hyperplasia of the mucous neck cells that displayed a strong immunoreactivity for parietal cell H+/K+-ATPase. Ghrelin mRNA levels were reduced by 2-fold in remaining fundic mucosa after VSG and 10-fold in GP after RYGB. In the antrum, gastrin mRNA levels were reduced after VSG in line with the reduced number of gastrin positive cells. This study reports novel and important observations dealing with the remaining gastric mucosa after RYGB and VSG. The data demonstrate, for the first time, a hyperplasia of the mucous neck cells, a transit cell population of the stomach bearing differentiating capacities into zymogenic and peptic cells.

Seven novel deleterious LEPR mutations found in early-onset obesity: a ΔExon6-8 shared by subjects from Reunion Island, France, suggests a founder effect.

CONTEXT: Infrequent mutations have been reported in the leptin receptor (LEPR) gene in humans with morbid obesity and endocrine disorders. However LEPR mutations are rarely examined in large populations from different ethnicities in a given country. OBJECTIVE: We estimated the prevalence of LEPR mutations in French patients with severe obesity and evaluated mutated patients' phenotype. DESIGN AND PATIENTS: We sequenced the LEPR gene in 535 morbidly obese French participants. We conducted clinical investigations to determine whether individuals with a novel shared mutation display particular characteristics relative to obesity history, body composition, hormonal functions, and the outcome of bariatric surgery. RESULTS: We identified 12 patients with a novel LEPR mutation (p.C604G, p.L786P, p.H800_N831del, p.Y422H, p.T711NfsX18, p.535-1G>A, p.P166CfsX7). Six unrelated subjects were carriers of the p.P166CfsX7 mutation leading to deletion overlapping exons 6 to 8. All subjects originated from Reunion Island (France). Their clinical features (severe early-onset obesity, food impulsivity, and hypogonadotropic hypogonadism) did not differ from other new LEPR mutation carriers. Results concerning weight loss surgery were inconsistent in homozygous LEPR mutation carriers. Heterozygous LEPR mutation carriers exhibited variable severity of obesity and no endocrine abnormality. CONCLUSION: Among seven newly discovered LEPR mutations in this French obese population, we identified a LEPR frameshift mutation shared by six subjects from Reunion Island. This observation suggests a founder effect in this Indian Ocean island with high prevalence of obesity and supports a recommendation for systematic screening for this mutation in morbidly obese subjects in this population.

Homozygous leptin receptor mutation due to uniparental disomy of chromosome 1: response to bariatric surgery.

CONTEXT: Severe early-onset obesity with major hyperphagia associated with hypogonadotropic hypogonadism is recognized as the main clinical presentation of leptin (LEP) or LEP receptor (LEPR) gene complete deficiency. In a few reported cases, homozygous mutations have been found in patients from consanguineous families. Care of LEPR-deficient patients is complicated because they cannot benefit from LEP treatment. Furthermore, gastric surgery may not be recommended in such genetic hypothalamic obesity. OBJECTIVE: We investigated in a morbidly obese patient the genetic origin of his obesity and evaluated the benefit of bariatric surgery in this case. SUBJECT AND METHODS: The patient exhibited severe early-onset obesity with hyperphagia and delayed puberty in a nonobese family. He had clinical and hormonal follow-up from 3 to 26 years of age. Gastroplasty procedures were undertaken when he was 16 and 18 years old. LEPR genetic analysis of the patient and his relatives was performed. RESULTS: A new homozygous LEPR sequence frameshift, predicted to generate a truncated protein from a premature stop codon in exon 14, was identified in the proband inherited from two paternal copies of chromosome 1 (isodisomy). Vertical ring gastroplasty was sufficient to induce and maintain a 40-kg weight loss into adulthood. CONCLUSION: We described the first case of a patient with chromosome 1 uniparental isodisomy revealed by molecular analysis of LEPR. In this case, gastroplasty may be partially effective for weight control as illustrated.

Melanocortin-4 receptor mutations and polymorphisms do not affect weight loss after bariatric surgery.

Bariatric surgery is the most effective long term weight-loss therapy for severe and morbidly obese patients. Melanocortin-4 Receptor (MC4R) mutations, the most frequent known cause of monogenic obesity, affect the regulation of energy homeostasis. The impact of such mutations on weight loss after bariatric surgery is still debated.The objective is to determine the impact of MC4R status on weight loss in obese subjects over one year after bariatric surgery.A total of 648 patients, who were referred to bariatric surgery in a single clinical nutrition department, were genotyped for their MC4R status. The following four groups were categorized: functional MC4R mutations, MC4R single nucleotide polymorphisms (SNPs): Val103Ile (V103L) and Ile251Leu (I251L), MC4R variant rs17782313 (downstream of MC4R) and MC4R SNP A-178C on the promoter. Each patient was matched with two randomly paired controls without mutation. Matching factors were age, sex, baseline weight and type of surgery procedure (Roux-en-Y gastric bypass and adjustable gastric banding). We compared weight loss between cases and controls at 3, 6 and 12 months after surgery.Among 648 patients, we identified 9 carriers of functional MC4R mutations, 10 carriers of MC4R V103L and I251L SNPs, 7 carriers of the rs17792313 variant and 22 carriers of the A-178C SNP. Weight loss at 3, 6 and 12 months did not differ between cases and controls, whatever the MC4R mutations.This is the first case-control study to show that MC4R mutations and polymorphisms do not affect weight loss and body composition over one year after bariatric surgery.