Autoantibodies reactive to adrenocorticotropic hormone can alter cortisol secretion in both aggressive and nonaggressive humans.

Violent aggression in humans may involve a modified response to stress, but the underlying mechanisms are not well understood. Here we show that naturally present autoantibodies reactive to adrenocorticotropic hormone (ACTH) exhibit distinct epitope-binding profiles to ACTH peptide in subjects with a history of violent aggression compared with controls. Namely, while nonaggressive male controls displayed a preferential IgG binding to the ACTH central part (amino acids 11-24), subjects who had committed violent acts of aggression had IgG with increased affinity to ACTH, preferentially binding to its N terminus (amino acids 1-13). Purified IgGs from approximately half of the examined sera were able to block ACTH-induced cortisol secretion of human adrenal cells in vitro, irrespective of the source of sample (from a control subject or a violent aggressor). Nevertheless, in the resident-intruder test in mice, i.p. injection of residents with ACTH and IgG from aggressive subjects, but not from control subjects, shortened latency for the first attack against intruders. Immunohistochemical screening of violent aggressors' sera on rat brain and pituitary sections did not show IgG binding to ACTH-producing cells, but 4 of 16 sera revealed selective binding to a nonidentified antigen in vasopressinergic neurons of the hypothalamic paraventricular and supraoptic nuclei. Thus, the data show that ACTH-reactive plasmatic IgGs exhibit differential epitope preference in control and violently aggressive subjects. These IgGs can modulate ACTH-induced cortisol secretion and, hence, are involved in the regulation of the stress response. However, the possible role of ACTH-reactive autoantibodies in aggressive behavior needs further investigation.

Commensal Hafnia alvei strain reduces food intake and fat mass in obese mice-a new potential probiotic for appetite and body weight management.

BACKGROUND/OBJECTIVES: Based on the recent identification of E.coli heat shock protein ClpB as a mimetic of the anorexigenic α-melanocyte stimulating hormone (α-MSH), the objective of this study was to preclinically validate Hafnia alvei, a ClpB-producing commensal bacterium as a potential probiotic for appetite and body weight management in overweight and obesity. METHODS: The involvement of enterobacterial ClpB in the putative anti-obesity effects was studied using ClpB-deficient E.coli. A food-grade H. alvei HA4597 strain synthetizing the ClpB protein with an α-MSH-like motif was selected as a candidate probiotic to be tested in ob/ob and high-fat diet (HFD)-fed obese and overweight mice. The relevance of the enterobacterial ClpB gene to human obesity was studied by in silico analysis of fecal metagenomes of 569 healthy individuals from the "MetaHIT" database. RESULTS: Chronic per os administration of native but not ClpB-deficient E.coli strain reduced body weight gain (p < 0.05) and daily meal frequency (p < 0.001) in ob/ob mice. Oral gavage of H.alvei for 18 and 46 days in ob/ob and HFD-fed obese mice, respectively, was well tolerated, reduced body weight gain and fat mass in both obesity models (p < 0.05) and decreased food intake in hyperphagic ob/ob mice (p < 0.001). Elevated fat tissue levels of phosphorylated hormone-sensitive lipase were detected in H.alvei -treated ob/ob mice (p < 0.01). Enterobacterial ClpB gene richness was lower in obese vs. non-obese humans (p < 0.0001) and correlated negatively with BMI in genera of Enterobacter, Klebsiella and Hafnia. CONCLUSIONS: H.alvei HA4597 strain reduces food intake, body weight and fat mass gain in hyperphagic and obese mice. These data combined with low enterobacterial ClpB gene abundance in the microbiota of obese humans provide the rationale for using H.alvei as a probiotic for appetite and body weight management in overweight and obesity.

Chronic colitis-induced visceral pain is associated with increased anxiety during quiescent phase.

Inflammatory bowel diseases (IBD) are characterized by repetition of flares and remission periods leading to chronic postinflammatory sequelae. Among postinflammatory sequelae, one-third of patients with IBD are suffering from functional symptoms or psychological comorbidities that persist during remission. The aim of our study was to assess functional and behavioral sequelae of chronic colitis in rats with quiescent intestinal inflammation. Chronic colitis was induced by a weekly intrarectal injection of increasing concentrations of trinitrobenzene sulfonic acid (TNBS) for 3 wk (15-45 mg of TNBS) in 30 rats, whereas the control rats (n = 24) received the vehicle. At 50 days post-TNBS, visceral sensitivity was assessed by visceromotor response to colorectal distension, and transient receptor potential vanilloid type 1 (TRPV1) expression was also quantified in the colon and dorsal root ganglia. Barrier function and inflammatory response were assessed by studying intestinal permeability, tight junction protein, myeloperoxidase activity, histological score, and cytokine production (IL-6, IL-10, and TNF-α). Anxiety behavioral tests were performed from 50 to 64 days after the last TNBS injection. Chronic TNBS induced 1) a visceral hypersensitivity (P = 0.03), 2) an increased colon weight-to-length ratio (P = 0.01), 3) higher inflammatory and fibrosis scores (P = 0.0390 and P = 0.0016, respectively), and 4) a higher colonic IL-6 and IL-10 production (P = 0.008 and P = 0.005, respectively) compared with control rats. Intestinal permeability, colonic production of TNF-α, myeloperoxidase activity, and TRPV1 expression did not differ among groups. Chronic TNBS increased anxiety-related behavior in the open-field test and in the acoustic stress test. In conclusion, chronic colitis induced functional sequelae such as visceral hypersensitivity and increased anxiety with a low-grade intestinal inflammation. Development of a representative animal model will allow defining novel therapeutic approaches to achieve a better management of IBD-related sequelae. NEW & NOTEWORTHY Patients with inflammatory bowel diseases have impaired quality of life. Therapeutic progress to control mucosal inflammation provides us an opportunity to develop novel approaches to understand mechanisms behind postinflammatory sequelae. We used a chronic colitis model to study long-term sequelae on visceral pain, gut barrier function, and psychological impact. Chronic colitis induced functional symptoms and increased anxiety in the remission period. It might define novel therapeutic approaches to achieve a better inflammatory bowel disease-related sequelae management.

Elevated plasma concentrations of bacterial ClpB protein in patients with eating disorders.

OBJECTIVE: Caseinolytic protease B (ClpB) produced by Enterobacteria, such as Escherichia coli, has been identified as a conformational mimetic of α-melanocyte-stimulating hormone (α-MSH), an anorexigenic and anxiogenic neuropeptide. In mice, ClpB induces α-MSH cross-reactive antibodies and activates anorexigenic brain neurons. In patients with eating disorders (ED), anti-ClpB and anti-α-MSH antibodies correlate with psychopathological traits. However, it is not known if ClpB is present in human plasma including ED patients. METHODS: Plasma concentrations of ClpB were measured using a recently developed ClpB immunoassay in female patients with anorexia nervosa, bulimia nervosa, and binge-eating disorder and compared with healthy participants, all characterized by the Eating Disorder Inventory-2 (EDI-2) scale. RESULTS: We found that ClpB was readably detectable in plasma of healthy participants and ED patients and that its concentrations were elevated in ED patients, without significant differences in patient's subgroups. Plasma ClpB concentrations correlated with the EDI-2 scores, with α-MSH as well as with plasma levels of anti-ClpB and anti-α-MSH antibodies. DISCUSSION: These data revealed that bacterial ClpB is naturally present in human plasma and that its concentrations can be elevated in ED patients and associated with ED-related psychopathological traits. These results support a link between bacterial ClpB and the ED pathophysiology. © 2016 Wiley Periodicals, Inc. (Int J Eat Disord 2016; 49:805-808).

Glutamine enema regulates colonic ubiquitinated proteins but not proteasome activities during TNBS-induced colitis leading to increased mitochondrial activity.

Ubiquitin proteasome system contributes to the regulation of intestinal inflammatory response as its inhibition is associated with tissue damage improvement. We aimed to evaluate whether glutamine is able to limit inflammation by targeting ubiquitin proteasome system in experimental colitis. Colitis was induced in male rats by intrarectal instillation of 2-4-6-trinitrobenzen sulfonic acid (TNBS) at day 1. From day 2 to day 6, rats daily received either an intrarectal instillation of PBS (TNBS/PBS group) or glutamine (TNBS/Gln). Rats were euthanized at day 7 and colonic samples were taken to evaluate ubiqutinated proteins by proteomic approach combining 2D electrophoresis and immunoblots directed against ubiquitin. Results were then confirmed by evaluating total expression of proteins and mRNA levels. Survival rate, TNFα, and IL-1ß mRNA were improved in TNBS/Gln compared with TNBS/PBS (p < 0.05). Proteasome activities were affected by TNBS but not by glutamine. We identified eight proteins that were less ubiquitinated in TNBS/PBS compared with controls with no effect of glutamine. Four proteins were more ubiquitinated in TNBS/PBS group and restored in TNBS/Gln group. Finally, 12 ubiquitinated proteins were only affected by glutamine. Among proteins affected by glutamine, eight proteins (GFPT1, Gapdh, Pkm2, LDH, Bcat2, ATP5a1, Vdac1, and Vdac2) were involved in metabolic pathways. In conclusion, glutamine may regulate ubiquitination process during intestinal inflammation.

A missense mutation in the agouti signaling protein gene (ASIP) is associated with the no light points coat phenotype in donkeys.

BACKGROUND: Seven donkey breeds are recognized by the French studbook and are characterized by a black, bay or grey coat colour including light cream-to-white points (LP). Occasionally, Normand bay donkeys give birth to dark foals that lack LP and display the no light points (NLP) pattern. This pattern is more frequent and officially recognized in American miniature donkeys. The LP (or pangare) phenotype resembles that of the light bellied agouti pattern in mouse, while the NLP pattern resembles that of the mammalian recessive black phenotype; both phenotypes are associated with the agouti signaling protein gene (ASIP). FINDINGS: We used a panel of 127 donkeys to identify a recessive missense c.349 T > C variant in ASIP that was shown to be in complete association with the NLP phenotype. This variant results in a cysteine to arginine substitution at position 117 in the ASIP protein. This cysteine is highly-conserved among vertebrate ASIP proteins and was previously shown by mutagenesis experiments to lie within a functional site. Altogether, our results strongly support that the identified mutation is causative of the NLP phenotype. CONCLUSIONS: Thus, we propose to name the c.[349 T > C] allele in donkeys, the a(nlp) allele, which enlarges the panel of coat colour alleles in donkeys and ASIP recessive loss-of-function alleles in animals.

Two recessive mutations in FGF5 are associated with the long-hair phenotype in donkeys.

BACKGROUND: Seven donkey breeds are recognized by the French studbook. Individuals from the Pyrenean, Provence, Berry Black, Normand, Cotentin and Bourbonnais breeds are characterized by a short coat, while those from the Poitou breed (Baudet du Poitou) are characterized by a long-hair phenotype. We hypothesized that loss-of-function mutations in the FGF5 (fibroblast growth factor 5) gene, which are associated with a long-hair phenotype in several mammalian species, may account for the special coat feature of Poitou donkeys. To the best of our knowledge, mutations in FGF5 have never been described in Equidae. METHODS: We sequenced the FGF5 gene from 35 long-haired Poitou donkeys, as well as from a panel of 67 short-haired donkeys from the six other French breeds and 131 short-haired ponies and horses. RESULTS: We identified a recessive c.433_434delAT frameshift deletion in FGF5, present in Poitou and three other donkey breeds and a recessive nonsense c.245G > A substitution, present in Poitou and four other donkey breeds. The frameshift deletion was associated with the long-hair phenotype in Poitou donkeys when present in two copies (n = 31) or combined with the nonsense mutation (n = 4). The frameshift deletion led to a stop codon at position 159 whereas the nonsense mutation led to a stop codon at position 82 in the FGF5 protein. In silico, the two truncated FGF5 proteins were predicted to lack the critical ß strands involved in the interaction between FGF5 and its receptor, a mandatory step to inhibit hair growth. CONCLUSIONS: Our results highlight the allelic heterogeneity of the long-hair phenotype in donkeys and enlarge the panel of recessive FGF5 loss-of-function alleles described in mammals. Thanks to the DNA test developed in this study, breeders of non-Poitou breeds will have the opportunity to identify long-hair carriers in their breeding stocks.

Description of Lifestyle, Including Social Life, Diet and Physical Activity, of People ≥90 years Living in Ikaria, a Longevity Blue Zone.

A cross-sectional observational study was conducted to describe the lifestyle of people ≥90 years, living in Evdilos or Raches, two municipalities of the Greek island of Ikaria, classified a longevity blue zone. The 71 participants were interviewed and underwent the Mediterranean Islands study food frequency questionnaire (MEDIS-FFQ) and the international physical activity questionnaire (IPAQ). The frequency of social contacts was daily for 77.9% of participants, weekly for 16.1%, and monthly for 5.9%. Most participants (90.0%) believed in God, and 81.4% took part in religious events. A total of 62.0% attended Panigiria festivals. Access to primary health care was considered difficult in the past for 66.2% of participants, while 22.1% felt that it remained difficult at the time of the survey. The level of adherence to the Mediterranean diet was 62.7% (61.6% in women and 64.0% in men). Physical activity levels were moderate or high for 71.8% of participants (59.5% of women and 85.3% of men). In conclusion, the participants had a very high level of family solidarity, social interaction and physical activity. The results concerning the Mediterranean diet are less convincing. It would be interesting to study the impact of these factors on the longevity of the oldest old aged people living in Ikaria.

Effects of Bacterial CLPB Protein Fragments on Food Intake and PYY Secretion.

CLPB (Caseinolytic peptidase B) protein is a conformational mimetic of α-MSH, an anorectic hormone. Previous in vivo studies have already shown the potential effect of CLPB protein on food intake and on the production of peptide YY (PYY) by injection of E. coli wild type (WT) or E. coli ΔClpB. However, until now, no study has shown its direct effect on food intake. Furthermore, this protein can fragment naturally. Therefore, the aim of this study was (i) to evaluate the in vitro effects of CLPB fragments on PYY production; and (ii) to test the in vivo effects of a CLPB fragment sharing molecular mimicry with α-MSH (CLPB25) compared to natural fragments of the CLPB protein (CLPB96). To do that, a primary culture of intestinal mucosal cells from male Sprague-Dawley rats was incubated with proteins extracted from E. coli WT and ΔCLPB after fragmentation with trypsin or after a heat treatment of the CLPB protein. PYY secretion was measured by ELISA. CLPB fragments were analyzed by Western Blot using anti-α-MSH antibodies. In vivo effects of the CLPB protein on food intake were evaluated by intraperitoneal injections in male C57Bl/6 and ob/ob mice using the BioDAQ® system. The natural CLPB96 fragmentation increased PYY production in vitro and significantly decreased cumulative food intake from 2 h in C57Bl/6 and ob/ob mice on the contrary to CLPB25. Therefore, the anorexigenic effect of CLPB is likely the consequence of enhanced PYY secretion.

Specific features of the oldest old from the Longevity Blue Zones in Ikaria and Sardinia.

Human longevity may be found in single individuals as well as in the population as a whole ("population longevity"). Longevity Blue Zones (LBZs), which are areas with an unusually high number of oldest old, have been identified in Sardinia and the Greek island of Ikaria. We compared the lifestyle, health status and some genetic markers of the LBZ populations with those of reference populations from Italy and Greece; the data were extracted from the GEHA database. In the LBZs, the proportion of individuals who never married or were married and still living with their spouse was significantly greater. Nonagenarians males and females with a high self‒perception of optimism and/or a high score for self-rated health were also found in larger proportions in LBZs. Among the variables with lower frequency were the proportion of the widowed, the percentage of subjects who had suffered a stroke and the frequency of Apoε4 and Apoε2 and the TT genotype of FOXO3A gene. Compared to behavioral and health indicators, the impact of genetic factors might be relatively less important in the LBZs. Nevertheless, further research is needed to identify potential epigenetic traits that might play a predominant role due to the interaction between genetics and the human and physical environments.

Intestinal lymphatic alteration in mouse models of energy imbalance.

In obesity or anorexia, changes in body composition and mostly alterations in fat mass distribution are observed. The lymphatic system, which is implicated in fat absorption, might play a major role in the phenotype and development of these pathologies. In this study, two mice animal models were used: the high-fat diet model used for obesity and the activity-based anorexia model for anorexia. Lymphatic system marker levels were measured by reverse transcriptase quantitative polymerase chain reaction on the different parts of the intestine. Moreover, the effects of these models were evaluated on lymphatic fat absorption using lipidic tracer. Using these two models, lymphatic system alterations were observed. Indeed, whether in the obesity or the anorectic model, lymphatic fat absorption modifications were noticed with an increase of this parameter in the anorectic mice and a decrease in obesity. Expression levels of lymphatic markers also were impaired in these models. Both obesity and anorectic models induced lymphatic system alterations mainly in the jejunum and ileum parts of the intestine. These alterations are associated with lipid absorption modifications.

Plasma Peptide Concentrations and Peptide-Reactive Immunoglobulins in Patients with Eating Disorders at Inclusion in the French EDILS Cohort (Eating Disorders Inventory and Longitudinal Survey).

Eating disorders (EDs) are increasingly frequent. Their pathophysiology involves disturbance of peptide signaling and the microbiota-gut-brain axis. This study analyzed peptides and corresponding immunoglobulin (Ig) concentrations in groups of ED. In 120 patients with restrictive (R), bulimic (B), and compulsive (C) ED, the plasma concentrations of leptin, glucagon-like peptide-1 (GLP-1), peptide YY (PYY), and insulin were analyzed by Milliplex and those of acyl ghrelin (AG), des-acyl ghrelin (DAG), and α-melanocyte-stimulating hormone (α-MSH) by ELISA kits. Immunoglobulin G (in response to an antigen) concentrations were analyzed by ELISA, and their affinity for the respective peptide was measured by surface plasmon resonance. The concentrations of leptin, insulin, GLP-1, and PYY were higher in C patients than in R patients. On the contrary, α-MSH, DAG, and AG concentrations were higher in R than in C patients. After adjustment for body mass index (BMI), differences among peptide concentrations were no longer different. No difference in the concentrations of the IgG was found, but the IgG concentrations were correlated with each other. Although differences of peptide concentrations exist among ED subtypes, they may be due to differences in BMI. Changes in the concentration and/or affinity of several anti-peptide IgG may contribute to the physiopathology of ED or may be related to fat mass.

Bacterial Protein Mimetic of Peptide Hormone as a New Class of Protein- based Drugs.

Specific peptide molecules classified as hormones, neuropeptides and cytokines are involved in intercellular signaling regulating various physiological processes in all organs and tissues. This justifies the peptidergic signaling as an attractive pharmacological target. Recently, a protein mimetic of a peptide hormone has been identified in Escherichia coli suggesting the potential use of specific bacterial proteins as a new type of peptide-like drugs. We review the scientific rational and technological approaches leading to the identification of the E. coli caseinolytic protease B (ClpB) homologue protein as a conformational mimetic of α-melanocyte-stimulating hormone (α-MSH), a melanocortin peptide critically involved in the regulation of energy homeostasis in humans and animals. Theoretical and experimental backgrounds for the validation of bacterial ClpB as a potential drug are discussed based on the known E. coli ClpB amino acid sequence homology with α-MSH. Using in silico analysis, we show that other protein sources containing similar to E. coli ClpB α-MSH-like epitopes with potential biological activity may exist in Enterobacteriaceae and in some Brassicaceae. Thus, the original approach leading to the identification of E. coli ClpB as an α-MSH mimetic protein can be applied for the identification of mimetic proteins of other peptide hormones and development of a new type of peptide-like protein-based drugs.

Assessment of the Health Status of the Oldest Olds Living on the Greek Island of Ikaria: A Population Based-Study in a Blue Zone.

OBJECTIVE: To describe the demographic characteristics, socio-economic status, functional status (autonomy, strength), and health status (cognitive and thymic functions, cardiovascular risk factors, and nutritional status) of the oldest olds living on the Greek island of Ikaria. We also try to explain the longevity observed in this population. METHODS: A cross-sectional observational study of people aged 90 and over living in both municipalities of north-western Ikaria (Evdilos and Raches) was conducted over one year, from October 21, 2012 to October 21, 2013. The participants were interviewed (medical history), had a brief clinical examination, and underwent standardized geriatric assessments including the Geriatric Depression Scale (GDS-15), the Mini-Mental-State Examination (MMSE), the Activities of Daily Living (ADL), the Instrumental ADL (IADL), and an assessment of grip strength. RESULTS: Seventy-one persons (37 females, 34 males), aged 94.1 years on average, were interviewed at their homes. Seven percent were current smokers (females 5.4%, males 8.8%). Hypertension was diagnosed in 70.4% of participants, diabetes in 19.7%, hypercholesterolemia in 12.7%, and obesity in 17.2%; 66.0% of the population had one chronic disease or more. The mean score for the GDS-15 scale was 3.7/15.0, 23.7/30.0 for the MMSE, 4.0/6.0 for the ADL, and 4.2/8.0 in females and 3.6/5.0 in males for the IADL. Grip strength was 17.0 kg in females and 26.5 kg in males. CONCLUSIONS: This study provides an overview of the socio-demographic and medical characteristics of the oldest olds living in a longevity Blue Zone.

Hafnia alvei HA4597 Strain Reduces Food Intake and Body Weight Gain and Improves Body Composition, Glucose, and Lipid Metabolism in a Mouse Model of Hyperphagic Obesity.

Use of new generation probiotics may become an integral part of the prevention and treatment strategies of obesity. The aim of the present study was to test the efficacy of a potential probiotic strain of lactic bacteria Hafnia alvei (H. alvei) HA4597™, in a mouse model of obesity characterized by both hyperphagia and diet-induced adiposity. For this purpose, 10-week-old high-fat-diet (HFD)-fed hyperphagic ob/ob male mice received a daily treatment with 1.4 × 1010 CFU of H. alvei for 38 days. Effects of H. alvei were compared to those of a lipase inhibitor orlistat (80 mg/kg daily) and a vehicle (NaCl 0.9%) in HFD-fed ob/ob mice. A control untreated group of ob/ob mice received the standard diet throughout the experiment. The vehicle-treated HFD group displayed increased food intake, worsening of adiposity, and glycemia. Treatment with H. alvei was accompanied by decreased body weight and fat-mass gain along with reduced food intake to the level of the standard-diet-fed mice. At the end of the experiment, the group treated with H. alvei showed a decrease of glycemia, plasma total cholesterol, and alanine aminotransferase. The orlistat-treated mice showed a lower rate of body weight gain but were hyperphagic and hyperglycemic. These results demonstrate the beneficial anti-obesity and metabolic effects of H. alvei HA4597™ in mice with obesity resulting from hyperphagia and diet-induced adiposity.

Proteome modifications of gut microbiota in mice with activity-based anorexia and starvation: Role in ATP production.

OBJECTIVE: Activity-based anorexia (ABA) in rodents is a behavioral model of anorexia nervosa, characterized by negative energy balance, hyperactivity, and dysbiosis of gut microbiota. Gut bacteria are known to produce energy substrates including adenosine triphosphate (ATP) and acetate. The aim of this study was to determine whether ABA alters the proteome of gut microbiota relevant to ATP and acetate production. METHODS: The ABA was developed in male mice and compared with food-restricted and ad libitum-fed conditions. Proteomic analysis of feces was performed using the two-dimentional gel electrophoresis and mass spectrometry. The in vitro ATP-producing capacity of proteins extracted from feces was assayed. RESULTS: Increased levels of the phosphoglycerate kinase, an ATP-producing glycolytic enzyme, was detected in feces of food-restricted mice and this enzyme was further increased in the ABA group. Starvation also upregulated several other proteins synthetized by order Clostridiales including Clostridiaceae and Lachnospiraceae families. No significant differences in the in vitro ATP-producing capacity by bacterial proteins from ABA, food-restricted, and ad libitum-fed control mice were found. However, plasma levels of acetate strongly tended to be increased in the activity groups including ABA mice. CONCLUSION: The data revealed that starvation in food-restricted and ABA mice induced proteome modification in gut bacteria favoring ATP production mainly by the order Clostridiales. However, this did not result in increased total ATP-production capacity by gut microbiota. These changes can be interpreted as an adaptation of specific gut bacteria to the host malnutrition beneficial for host survival.

Changes in Microbiota and Bacterial Protein Caseinolytic Peptidase B During Food Restriction in Mice: Relevance for the Onset and Perpetuation of Anorexia Nervosa.

Microbiota contributes to the regulation of eating behavior and might be implicated in the pathophysiology of anorexia nervosa. ClpB (Caseinolytic peptidase B) protein produced mainly by the Enterobacteriaceae family has been identified as a conformational mimetic of α-MSH, which could result in similar anorexigenic effects. The aim of this study was to highlight the role of the microbiome and the ClpB protein in deregulation and self-maintenance of anorexia pathology. Male C57Bl/6 mice were undergone to the ABA (Activity-Based Anorexia) protocol: after 5 days of acclimatization, both ABA and LFA (Limited Food Access) mice had progressively limited access to food until D17. At the end of protocol, the plasma ClpB concentration and Enterobacteriaceae DNA in colonic content were measured. As expected, dietary restriction induced lost weight in LFA and ABA mice. At D10, colonic permeability and plasma concentration of the ClpB protein were significantly increased in LFA and ABA mice vs. controls. At D17, plasma concentration of ClpB was increased in LFA and ABA mice and, it was correlated with proportion of Enterobacteriaceae in the faeces. These abnormally high ClpB concentrations and all associated factors, and therefore might contribute to the initiation and/or perpetuation of anorexia nervosa by interfering with satiety signaling.

Immunoglobulin G modulation of the melanocortin 4 receptor signaling in obesity and eating disorders.

Melanocortin 4 receptor (MC4R) plays a key role in regulation of appetite activated by its main ligand α-melanocyte-stimulating hormone (α-MSH) in both central and peripheral targets. α-MSH also binds to circulating immunoglobulins (Igs) but the functional significance of such immune complexes (ICs) in MC4R signaling in normal and pathological conditions of altered appetite has remained unknown. To address this question, we analyzed plasma levels, affinity kinetics, and binding epitopes of α-MSH-reactive IgG extracted from plasma samples of female patients with hyperphagic obesity, anorexia nervosa, bulimia nervosa, binge-eating disorder, and healthy controls. Ability of α-MSH/IgG IC to bind and activate human MC4R were studied in vitro and to influence feeding behavior in vivo in rodents. We found that α-MSH-reactive IgG were low in obese but increased in anorectic and bulimic patients and displayed different epitope and kinetics of IC formation. Importantly, while α-MSH/IgG IC from all subjects were binding and activating MC4R, the receptor binding affinity was decreased in obesity. Additionally, α-MSH/IgG IC had lower MC4R-mediated cAMP activation threshold as compared with α-MSH alone in all but not obese subjects. Furthermore, the cellular internalization rate of α-MSH/IgG IC by MC4R-expressing cells was decreased in obese but increased in patients with anorexia nervosa. Moreover, IgG from obese patients prevented central anorexigenic effect of α-MSH. These findings reveal that MC4R is physiologically activated by IC formed by α-MSH/IgG and that different levels and molecular properties of α-MSH-reactive IgG underlie biological activity of such IC relevant to altered appetite in obesity and eating disorders.

Affinity kinetics of leptin-reactive immunoglobulins are associated with plasma leptin and markers of obesity and diabetes.

Obese subjects display elevated plasma levels of leptin reflecting the phenomenon of leptin resistance. Here, we aimed to determine whether leptin-reactive immunoglobulins (Ig) are present in obese and type 2 diabetes (T2D) patients and whether their plasma levels and affinity kinetics may correlate with obesity and diabetes markers. We show that leptin levels are increased in obese patients with and without T2D. Although mean plasma levels of leptin-reactive IgG were similar between study groups, IgG in obese non-diabetic patients had increased dissociation rate and lower affinity (increased dissociation equilibrium constant value; KD). In controls and diabetic patients, the association rates of leptin IgG correlated negatively with obesity and diabetes markers, respectively. In contrast, KD values correlated positively with plasma leptin levels and obesity traits in our cohort, and with diabetes markers in both the total cohort and in the obese T2D group. Taken together, our data reveal that leptin-reactive IgG are present in healthy subjects, obese, and diabetic patients but display altered affinity kinetics in obesity. Increased IgG binding to leptin in healthy subjects associated with lower body mass index (BMI) suggests an enhancing role of IgG in leptin signaling. Accordingly, a decreased affinity of IgG for leptin, found in obese patients, can be relevant to leptin resistance.

Ghrelin-Reactive Immunoglobulins in Conditions of Altered Appetite and Energy Balance.

Part of circulating ghrelin is bound to immunoglobulins (Ig) protecting it from degradation and preserving its functional activity. This review summarizes the data on ghrelin- and desacyl-ghrelin-reactive IgG in conditions of altered appetite and energy balance. Plasma levels and affinity kinetics of such IgG were compared in patients with obesity and anorexia nervosa (AN) and in animal models of obesity including ob/ob mice, high-fat diet-induced obese mice, and obese Zucker rats as well as in mice after chronic food restriction and activity-based anorexia and in rats with methotrexate-induced anorexia. We show that plasmatic IgG in both obese humans and animals are characterized by increased affinity for ghrelin. In contrast, patients with AN and anorectic rodents all show lower affinity of ghrelin- and desacyl-ghrelin-reactive IgG, respectively, the changes which were not observed in non-anorectic, chronically starved mice. We also show that affinity of ghrelin-reactive IgG correlate with plasma levels of ghrelin. These data point to common mechanisms underlying modifications of affinity kinetics properties of ghrelin-reactive IgG during chronic alterations of energy balance in humans and rodents and support a functional role of such autoantibodies in ghrelin-mediated regulation of appetite.