Ghrelin: integrative neuroendocrine peptide in health and disease

Dysregulated brain-gut axis in the setting of traumatic brain injury: review of mechanisms and anti-inflammatory pharmacotherapies

Traumatic brain injury (TBI) is a chronic and debilitating disease, associated with a high risk of psychiatric and neurodegenerative diseases. Despite significant advancements in improving outcomes, the lack of effective treatments underscore the urgent need for innovative therapeutic strategies. The brain-gut axis has emerged as a crucial bidirectional pathway connecting the brain and the gastrointestinal (GI) system through an intricate network of neuronal, hormonal, and immunological pathways. Four main pathways are primarily implicated in this crosstalk, including the systemic immune system, autonomic and enteric nervous systems, neuroendocrine system, and microbiome. TBI induces profound changes in the gut, initiating an unrestrained vicious cycle that exacerbates brain injury through the brain-gut axis. Alterations in the gut include mucosal damage associated with the malabsorption of nutrients/electrolytes, disintegration of the intestinal barrier, increased infiltration of systemic immune cells, dysmotility, dysbiosis, enteroendocrine cell (EEC) dysfunction and disruption in the enteric nervous system (ENS) and autonomic nervous system (ANS). Collectively, these changes further contribute to brain neuroinflammation and neurodegeneration via the gut-brain axis. In this review article, we elucidate the roles of various anti-inflammatory pharmacotherapies capable of attenuating the dysregulated inflammatory response along the brain-gut axis in TBI. These agents include hormones such as serotonin, ghrelin, and progesterone, ANS regulators such as beta-blockers, lipid-lowering drugs like statins, and intestinal flora modulators such as probiotics and antibiotics. They attenuate neuroinflammation by targeting distinct inflammatory pathways in both the brain and the gut post-TBI. These therapeutic agents exhibit promising potential in mitigating inflammation along the brain-gut axis and enhancing neurocognitive outcomes for TBI patients.

Thyroid disorders and gastrointestinal dysmotility: an old association

Gastrointestinal motility symptoms may be closely related to thyroid diseases. Sometimes, such symptoms are the only thyroid disease-related clue although the degree of the symptoms may vary. The exact mechanism of action of thyroid hormones on gastrointestinal motility is not completely understood, however, a clue lies in the fact that muscle cell receptors can be directly acted upon by thyroxines. Both hypo- and hyperthyroidism can cause impairment of gastrointestinal motility, modifying structure and function of pharynx and esophagus, and regulating esophageal peristalsis through neuro-humoral interaction. In hyperthyroid patients, alterations of postprandial and basic electric rhythms have been observed at gastro-duodenal level, often resulting in slower gastric emptying. Gastric emptying may also be delayed in hypothyroidism, but an unrelated gastric mucosa-affecting chronic modification may also cause such pattern. Hyperthyroidism commonly show malabsorption and diarrhoea, while hypothyroidism frequently show constipation. In summary, it can be stated that symptoms of gastrointestinal motility dysfunction can be related to thyroid diseases, affecting any of the gastrointestinal segment. Clinically, the typical thyroid disease manifestations may be missing, borderline, or concealed because of intercurrent sicknesses. Motility-linked gastrointestinal problems may easily conceal a misdetected, underlying dysthyroidism that should be carefully analyzed. Here, we aim to elaborate on the associations between thyroid disorders and GI dysmotility and the common clinical manifestations associated with GI dysmotility.

Postoperative relative decrease in skeletal muscle mass as a predictor of quality of life in patients with gastric cancer

Low skeletal muscle mass reflects poor nutritional condition, which may impair the functional status and quality of life (QOL) of survivors of gastrectomy. The present cross-sectional study examined the association between a relative change in skeletal muscle mass and perceived postoperative health and QOL in patients with gastric cancer. The study comprised 74 patients (48 men and 26 women; median age, 68.5 years) who underwent surgery for stage I-III gastric cancer. Outcomes were measured using the Postgastrectomy Syndrome Assessment Scale-45, which was specifically developed to measure post-gastrectomy symptoms, living status, dissatisfaction with daily life and generic QOL. The skeletal muscle mass index (SMI) was estimated using computed tomography by tracing the area of the psoas major muscle to calculate the ΔSMI, defined as: (SMI before surgery-SMI at completion of the PGSAS-45 survey)/SMI before surgery x100. Associations between ΔSMI and health outcomes were assessed using univariate and multivariate analyses. The mean ΔSMI (SD) was 8.64% (10.6%). The effect size (Cohen's d) of ΔSMI <10% compared with ΔSMI ≥10% was 0.50 (95% CI: 0.02 to 0.97) for total symptom scores, -0.51 (-0.98 to -0.03) for general health, and -0.52 (-0.99 to -0.05) for the physical component summary (PCS). Multiple regression analysis showed that ΔSMI was significantly associated with PCS decline, and its standardized regression coefficient was -0.447 (-0.209 to -0.685). Determining ΔSMI may help clinicians to facilitate the objective evaluation of low skeletal mass, which reflects poor nutritional condition that can impair functional status and QOL of postoperative patients surviving gastrectomy.

Valproate-Induced Metabolic Syndrome

Valproic acid (VPA) and its salts (sodium calcium magnesium and orotic) are psychotropic drugs that are widely used in neurology and psychiatry. The long-term use of VPA increases the risk of developing adverse drug reactions (ADRs), among which metabolic syndrome (MetS) plays a special role. MetS belongs to a cluster of metabolic conditions such as abdominal obesity, high blood pressure, high blood glucose, high serum triglycerides, and low serum high-density lipoprotein. Valproate-induced MetS (VPA-MetS) is a common ADR that needs an updated multidisciplinary approach to its prevention and diagnosis. In this review, we consider the results of studies of blood (serum and plasma) and the urinary biomarkers of VPA-MetS. These metabolic biomarkers may provide the key to the development of a new multidisciplinary personalized strategy for the prevention and diagnosis of VPA-MetS in patients with neurological diseases, psychiatric disorders, and addiction diseases.

Multiple roles of ghrelin in breast cancer

Breast cancer is one of the most threatening malignant tumors in women worldwide; hence, investigators are continually performing novel research in this field. However, an accurate prediction of its prognosis and postoperative recovery remains difficult. The severity of breast cancer is patient-specific and affected by several health factors; thus, unknown mechanisms may affect its progression. This article analyzes existing literature on breast cancer, ranging from the discovery of ghrelin to its present use, and aims to provide a reference for future research into breast cancer mechanisms and treatment-plan improvement. Various parts of ghrelin have been associated with breast cancer by direct or indirect evidence. The ghrelin system may encompass the direction of expanding breast cancer treatment methods and prognostic indicators. Therefore, we compiled almost all studies on the relationship between the ghrelin system and breast cancer, including unacylated ghrelin, its GHRL gene, ghrelin O-acyltransferase, the receptor growth hormone secretagogue receptor, and several splice variants of ghrelin to lay the foundation for future research.

Roles of gastrointestinal polypeptides in intestinal barrier regulation

The intestinal barrier is a dynamic entity that is organized as a multilayer system and includes various intracellular and extracellular elements. The gut barrier functions in a coordinated manner to impede the passage of antigens, toxins, and microbiome components and simultaneously preserves the balanced development of the epithelial barrier and the immune system and the acquisition of tolerance to dietary antigens and intestinal pathogens.Numerous scientific studies have shown a significant association between gut barrier damage and gastrointestinal and extraintestinal diseases such as inflammatory bowel disease, celiac disease and hepatic fibrosis. Various internal and external factors regulate the intestinal barrier. Gastrointestinal peptides originate from enteroendocrine cells in the luminal digestive tract and are critical gut barrier regulators. Recent studies have demonstrated that gastrointestinal peptides have a therapeutic effect on digestive tract diseases, enhancing epithelial barrier activity and restoring the gut barrier. This review demonstrates the roles and mechanisms of gastrointestinal polypeptides, especially somatostatin (SST) and vasoactive intestinal peptide (VIP), in intestinal barrier regulation.

Ghrelin octanoylation by ghrelin O-acyltransferase: protein acylation impacting metabolic and neuroendocrine signalling

The acylated peptide hormone ghrelin impacts a wide range of physiological processes but is most well known for controlling hunger and metabolic regulation. Ghrelin requires a unique posttranslational modification, serine octanoylation, to bind and activate signalling through its cognate GHS-R1a receptor. Ghrelin acylation is catalysed by ghrelin O-acyltransferase (GOAT), a member of the membrane-bound O-acyltransferase (MBOAT) enzyme family. The ghrelin/GOAT/GHS-R1a system is defined by multiple unique aspects within both protein biochemistry and endocrinology. Ghrelin serves as the only substrate for GOAT within the human proteome and, among the multiple hormones involved in energy homeostasis and metabolism such as insulin and leptin, acts as the only known hormone in circulation that directly stimulates appetite and hunger signalling. Advances in GOAT enzymology, structural modelling and inhibitor development have revolutionized our understanding of this enzyme and offered new tools for investigating ghrelin signalling at the molecular and organismal levels. In this review, we briefly summarize the current state of knowledge regarding ghrelin signalling and ghrelin/GOAT enzymology, discuss the GOAT structural model in the context of recently reported MBOAT enzyme superfamily member structures, and highlight the growing complement of GOAT inhibitors that offer options for both ghrelin signalling studies and therapeutic applications.

Ghrelin as an Anti-Sepsis Peptide: Review

Sepsis continues to produce widespread inflammation, illness, and death, prompting intensive research aimed at uncovering causes and therapies. In this article, we focus on ghrelin, an endogenous peptide with promise as a potent anti-inflammatory agent. Ghrelin was discovered, tracked, and isolated from stomach cells based on its ability to stimulate release of growth hormone. It also stimulates appetite and is shown to be anti-inflammatory in a wide range of tissues. The anti-inflammatory effects mediated by ghrelin are a result of both the stimulation of anti-inflammatory processes and an inhibition of pro-inflammatory forces. Anti-inflammatory processes are promoted in a broad range of tissues including the hypothalamus and vagus nerve as well as in a broad range of immune cells. Aged rodents have reduced levels of growth hormone (GH) and diminished immune responses; ghrelin administration boosts GH levels and immune response. The anti-inflammatory functions of ghrelin, well displayed in preclinical animal models of sepsis, are just being charted in patients, with expectations that ghrelin and growth hormone might improve outcomes in patients with sepsis.

Correction of immunosuppression in aged septic rats by human ghrelin and growth hormone through the vagus nerve-dependent inhibition of TGF-β production

BACKGROUND

Co-administration of human ghrelin and growth hormone (GH) reverse immunosuppression in septic aged animals, but the mechanism remains elusive. Here, we hypothesize that ghrelin and GH co-treatment restores the immune response in aged septic rats by inhibiting the production of transforming growth factor-β (TGF-β), an immunoregulatory cytokine, through the vagus nerve.

METHODS

Male aged Fischer rats (22-23-month-old) were made septic by cecal ligation and puncture (CLP) with or without dissecting the vagus nerve (vagotomy). Human ghrelin and GH or vehicle (PBS) were administrated subcutaneously at 5 h post CLP. After 20 h of CLP, serum and spleens were harvested.

RESULTS

Serum TGF-β levels were increased in septic aged rats, while ghrelin and GH treatment significantly reduced its levels. Expression of TGF-β in the spleen was upregulated after sepsis, while ghrelin and GH treatment significantly inhibited its expression. TNF-α and IL-6 levels were significantly reduced after ex vivo LPS stimulation of splenocytes from rats that underwent CLP compared to sham rats; while these levels were significantly higher in splenocytes from ghrelin and GH-treated CLP rats compared to vehicle-treated CLP rats. Ghrelin and GH treatment reduced program death receptor-1 (PD-1) expression, increased human leukocyte antigen-DR (HLA-DR) expression, attenuated lymphopenia, and cleaved caspase-3 levels in the spleen of septic aged rats. Vagotomy diminished the beneficial effects of ghrelin and GH treatment in septic rats. In vitro, the addition of ghrelin, GH, or ghrelin and GH together had no effect on restoring immune response in splenocytes from CLP rats following LPS stimulation, indicating the requirement of the vagus nerve for ghrelin and GH's effect.

CONCLUSIONS

Ghrelin and GH attenuate immunosuppression in aged septic rats through the vagus nerve-dependent inhibition of TGF-β production.

The Cholinergic Anti-Inflammatory Pathway as a Conceptual Framework to Treat Inflammation-Mediated Renal Injury

BACKGROUND

The cholinergic anti-inflammatory pathway, positioned at the interface of the nervous and immune systems, is the efferent limb of the "inflammatory reflex" which mainly signals through the vagus nerve. As such, the brain can modulate peripheral inflammatory responses by the activation of vagal efferent fibers. Importantly, immune cells in the spleen express most cholinergic system components such as acetylcholine (ACh), choline acetyltransferase, acetylcholinesterase, and both muscarinic and nicotinic ACh receptors, making communication between both systems possible. In general, this communication down-regulates the inflammation, achieved through different mechanisms and depending on the cells involved.

SUMMARY

With the awareness that the cholinergic anti-inflammatory pathway serves to prevent or limit inflammation in peripheral organs, vagus nerve stimulation has become a promising strategy in the treatment of several inflammatory conditions. Both pharmacological and non-pharmacological methods have been used in many studies to limit organ injury as a consequence of inflammation. Key Messages: In this review, we will highlight our current knowledge of the cholinergic anti-inflammatory pathway, with emphasis on its potential clinical use in the treatment of inflammation-triggered kidney injury.

Anti-obesity effect of argel (Solenostemma argel) on obese rats fed a high fat diet

ETHNOPHARMACOLOGICAL RELEVANCE

Solenostemma argel (Argel) is a desert plant commonly used in Egyptian and Sudanese traditional medicine to suppress appetite, for treatment of diabetes, and as an antispasmodic and anti-inflammatory agent. Previously the anti-diabetic, hypolipidemic and lipase inhibitory activities of Argel were reported in animal studies and in-vitro assays. However, its specific mechanism of action as an anti-obesity agent has not been studied before.

AIM OF THE STUDY

Assessment of the possible anti-obesity effect of Solenostemma argel on diet-induced obesity and elucidation of its mechanism of action, as well as, standardization of the active plant extract.

MATERIALS AND METHODS

The ethanolic extract (EtOH-E) and its fractions (CH₂Cl₂-F: methylene chloride and BuOH-F: n-butanol) were prepared from the aerial parts of S. argel and studied at two dose levels; 200 and 400 mg kg^-1 in a model of high fat diet (HFD) fed rats. The animals (72 Male Wister rats) were assigned into 9 groups: group (i) fed with normal diet and groups (ii-iv) fed with high fat diet (HFD) for 16 weeks and treated with orlistat, EtOH-E, CH₂Cl₂-F and BuOH-F in the beginning of the 8th week. At the end of the experiment, blood samples were analysed for lipid and liver biomarkers, glucose and insulin levels, as well as, adipokines and inflammatory markers. Liver and adipose tissues were examined histopathologically and their homogenates were used to determine levels of oxidative stress markers and lipogenesis-related genes. Body weight was monitored weekly during the experiment.

RESULTS

Our data showed that consumption of S. argel significantly controlled weight gain, attenuated liver steatosis, improved the lipid profile, modulated adipokines activities, increased β-oxidation gene expression, as well as, decreased the expression of lipogenesis-related genes and ameliorated inflammatory and lipid peroxidation derangement. The ethanolic extract was also standardized using LC-MS analysis for its content of stemmoside C.

CONCLUSIONS

The current study revealed that S. argel is a promising Egyptian natural drug, rich in pregnane glycosides, and could be considered a new therapeutic candidate targeting obesity.

The Role of the Small Bowel in Unintentional Weight Loss after Treatment of Upper Gastrointestinal Cancers

Upper gastrointestinal (GI) cancers are responsible for significant mortality and morbidity worldwide. To date, most of the studies focused on the treatments’ efficacy and post-treatment survival rate. As treatments improve, more patients survive long term, and thus the accompanying complications including unintentional weight loss are becoming more important. Unintentional weight loss is defined as >5% of body weight loss within 6–12 months. Malignancies, particularly GI cancers, are diagnosed in approximately 25% of patients who present with unintentional weight loss. Whereas some recent studies discuss pathophysiological mechanisms and new promising therapies of cancer cachexia, there is a lack of studies regarding the underlying mechanism of unintentional weight loss in patients who are tumor free and where cancer cachexia has been excluded. The small bowel is a central hub in metabolic regulation, energy homeostasis, and body weight control throughout the microbiota-gut-brain axis. In this narrative review article, the authors discussed the impacts of upper GI cancers’ treatment modalities on the small bowel which may lead to unintentional weight loss and some new promising therapeutic agents to treat unintentional weight loss in long term survivors after upper GI operations with curative intent.

[Ghrelin Physiology and Pathophysiology: Focus on the Cardiovascular System]

Ghrelin is a multifunctional peptide hormone, mainly synthesized by P / D1 cells of the stomach fundus mucosa. Its basic effect, which is realized via GHS-R1 α receptor in the arcuate and the ventromedial nucleuses of hypothalamus, is stimulation of the synthesis of pituitary hormones. Ghrelin is involved in control of appetite and energy balance, regulation of carbohydrate and lipid metabolism, cell proliferation and apoptosis, as well as modulation of functioning of gastrointestinal, cardiovascular, pulmonary and immune systems. It was found that cardiomyocytes are able to synthesize ghrelin. High concentrations of GHS-R1α in the heart and major blood vessels evidence for its possible participation in functioning of cardiovascular system. Ghrelin inhibits apoptosis of cardiomyocytes and endothelial cells, and improves the functioning of the left ventricle (LV) after injury of ischemia-reperfusion mechanism. In rats with heart failure (HF) ghrelin improves LV function and attenuates development of cardiac cachexia. In addition, ghrelin exerts vasodilatory effects in humans, improves cardiac function and reduces peripheral vascular resistance in patients with chronic HF. The review contains of the predictive value of ghrelin in the development and prevention of cardiovascular disease.

Serum ghrelin is associated with risk of colorectal adenocarcinomas in the ATBC study

BACKGROUND

Colorectal cancers are the third most common cancers in women and men in the USA. While dietary and lifestyle factors such as Western diet, physical inactivity and obesity have been linked to an increased risk of this malignancy, the mechanisms for these associations are unclear. GI hormones, including ghrelin, are involved in energy balance by mediating appetite and metabolism; however, the association between ghrelin and colorectal cancer has not been studied.

METHODS

We conducted a case-control study nested within the all-male Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study of Finnish smokers (aged 50-69 years) to examine serum ghrelin concentration and colorectal cancer risk. Data from 284 colon and 239 rectal cancers and 523 controls (matched on age, date of blood draw and serum availability) were analysed. ORs and 95% CIs were calculated using multivariable (conditional) logistic regression.

RESULTS

Overall, low-serum ghrelin was significantly associated with increased risk of colorectal cancer (Q1 vs Q4: OR:1.57, 95% CI 1.05 to 2.34). For individuals developing tumours within 10 years of blood draw, those in the lowest quartile of serum ghrelin concentrations were statistically significantly more likely to develop colorectal cancers than those with higher serum ghrelin concentrations (OR: 10.86, 95% CI 5.01 to 23.55). However, for individuals with tumours developing more than 20 years after blood draw, low-serum ghrelin concentrations were associated with a decreased risk of colorectal cancer relative to those with the highest serum ghrelin concentrations (OR: 0.26, 95% CI 0.11 to 0.64).

CONCLUSION

Low-serum ghrelin was associated with an increased colorectal cancer risk within 10 years of blood draw with a decreased risk for developing colorectal cancer more than 20 years after blood draw. These results suggest that ghrelin concentrations may vary across the carcinogenic process.

The protective role of human ghrelin in sepsis: Restoration of CD4 T cell proliferation

Decrease of CD4 T cell numbers causes immunosuppression in sepsis. We previously showed the beneficial role of ghrelin in sepsis. We hypothesize that the protective outcome of ghrelin in sepsis is mediated partially through the restoration of CD4 T cells’ proliferation. Sepsis was induced in mice by cecal ligation and puncture (CLP). The percentage of CD4 T cells in spleen was assessed by flow cytometry and their proliferation was determined by carboxyfluorescein succinimidyl ester (CSFE). Compared to sham mice, the percentages of splenic CD4 T cells were reduced by 20%, 21%, and 29% at day 1, 2 and 3 after CLP, respectively. Human ghrelin was given to 3 day septic mice by s.c. injection at 5 and 24 h after CLP. Treatment with ghrelin restored the loss of CD4 T cells by increasing their proliferation in septic mice. The expression of cyclin D1 and B1 was significantly increased, while the expression of p57 was decreased in ghrelin-treated mice compared to vehicle-treated mice in sepsis. Treatment with human ghrelin significantly increased the p-AKT levels in the spleen compared to vehicle-treated septic mice. Human ghrelin plays an important role in reestablishing the proliferation of CD4 T cells and serves as a promising therapeutic agent in sepsis.

Altered Neuroendocrine Immune Responses, a Two-Sword Weapon against Traumatic Inflammation

During the occurrence and development of injury (trauma, hemorrhagic shock, ischemia and hypoxia), the neuroendocrine and immune system act as a prominent navigation leader and possess an inter-system crosstalk between the reciprocal information dissemination. The fundamental reason that neuroendocrinology and immunology could mix each other and permeate toward the field of traumatology is owing to their same biological languages or chemical information molecules (hormones, neurotransmitters, neuropeptides, cytokines and their corresponding receptors) shared by the neuroendocrine and immune systems. The immune system is not only modulated by the neuroendocrine system, but also can modulate the biological functions of the neuroendocrine system. The interactive linkage of these three systems precipitates the complicated space-time patterns for the courses of traumatic inflammation. Recently, compelling evidence indicates that the network linkage pattern that initiating agents of neuroendocrine responses, regulatory elements of immune cells and effecter targets for immune regulatory molecules arouse the resistance mechanism disorders, which supplies the beneficial enlightenment for the diagnosis and therapy of traumatic complications from the view of translational medicine. Here we review the alternative protective and detrimental roles as well as possible mechanisms of the neuroendocrine immune responses in traumatic inflammation.

Ghrelin ameliorates acute lung injury induced by oleic acid via inhibition of endoplasmic reticulum stress

AIMS

Acute lung injury (ALI) is associated with excessive mortality and lacks appropriate therapy. Ghrelin is a novel peptide that protects the lung against ALI. This study aimed to investigate whether endoplasmic reticulum stress (ERS) mediates the protective effect of ghrelin on ALI.

MAIN METHODS

We used a rat oleic acid (OA)-induced ALI model. Pulmonary impairment was detected by hematoxylin and eosin (HE) staining, lung mechanics, wet/dry weight ratio, and arterial blood gas analysis. Plasma and lung content of ghrelin was examined by ELISA, and mRNA expression was measured by quantitative real-time PCR. Protein levels were detected by western blot.

KEY FINDINGS

Rats with OA treatment showed significant pulmonary injury, edema, inflammatory cellular infiltration, cytokine release, hypoxia and CO₂ retention as compared with controls. Plasma and pulmonary content of ghrelin was reduced in rats with ALI, and mRNA expression was downregulated. Ghrelin (10nmol/kg) treatment ameliorated the above symptoms, but treatment with the ghrelin antagonists D-Lys³ GHRP-6 (1μmol/kg) and JMV 2959 (6mg/kg) exacerbated the symptoms. ERS induced by OA was prevented by ghrelin and augmented by ghrelin antagonist treatment. The ERS inducer, tunicamycin (Tm) prevented the ameliorative effect of ghrelin on ALI. The decreased ratio of p-Akt and Akt induced by OA was improved by ghrelin treatment, and was further exacerbated by ghrelin antagonists.

SIGNIFICANCE

Ghrelin protects against ALI by inhibiting ERS. These results provide a new target for prevention and therapy of ALI.

Ghrelin and cancer progression

Ghrelin is a small peptide with 28 amino acids, and has been characterized as the ligand of the growth hormone secretagogue receptor (GHSR). In addition to its original function in stimulating pituitary growth hormone release, ghrelin is multifunctional and plays a role in the regulation of energy balance, gastric acid release, appetite, insulin secretion, gastric motility and the turnover of gastric and intestinal mucosa. The discovery of ghrelin and GHSR expression beyond normal tissues suggests its role other than physiological function. Emerging evidences have revealed ghrelin's function in regulating several processes related to cancer progression, especially in metastasis and proliferation. We further show the relative GHRL and GHSR expression in pan-cancers from The Cancer Genome Atlas (TCGA), suggesting the potential pathological role of the axis in cancers. This review focuses on ghrelin's biological function in cancer progression, and reveals its clinical significance especially the impact on cancer patient outcome.

Therapeutic effect of human ghrelin and growth hormone: Attenuation of immunosuppression in septic aged rats

Sepsis is a leading cause of mortality in intensive care units, and is more common in the geriatric population. The control of hyperinflammation has been suggested as a therapeutic approach in sepsis, but to date clinical trials utilizing this strategy have not lead to an effective treatment. In addition to hyperinflammation, patients with sepsis often experience a state of immunosuppression, which serves as an important determinant for increased morbidity and mortality. We previously used aged animals to demonstrate the effectiveness of combined treatment with human ghrelin (Ghr) and human growth hormone (GH) in improving organ injury and survival in septic animals. Here, we hypothesized that combined treatment with Ghr and GH could improve immune function in septic aged animals. Male 24-month-old rats were subjected to cecal ligation and puncture (CLP) for sepsis induction. Human Ghr (80nmol/kg BW) plus GH (50μg/kg BW) or vehicle (normal saline) was administrated subcutaneously at 5h after CLP. The ex vivo production of TNF-α, IL-6 and IL-10 to LPS-stimulation, as well as TNF-α, IL-6, IL-10 and IFN-γ production to anti-CD3/anti-CD28 antibody-stimulation, in splenocytes isolated 20h after CLP, was significantly decreased compared to production of these cytokines in splenocytes from sham animals. The production of cytokines from splenocytes isolated from septic animals that received the combined treatment, however, was significantly higher than from those isolated from vehicle-treated septic animals. Combined treatment prevented the loss of splenic CD4⁺ and CD8⁺ T cells in septic aged rats, and reduced lymphocyte apoptosis. Combined treatment also inhibited an increase in the regulatory T cell (T_reg) population and expression of the immune co-inhibitory molecule PD-1 in the spleens of septic aged rats. In contrast, expression of HLA-DR was increased after combined treatment with Ghr and GH. Based on these findings, we conclude that co-administration of Ghr and GH is a promising therapeutic tool for reversing immunosuppression caused by sepsis in the geriatric population. This article is part of a Special Issue entitled: Immune and Metabolic Alterations in Trauma and Sepsis edited by Dr. Raghavan Raju.

Neurobiochemical and psychological factors influencing the eating behaviors and attitudes in anorexia nervosa

The aim of this study was to determine the characteristic features which contribute to inappropriate eating attitudes in people suffering from anorexia nervosa, based on an analysis of recent data. Factors influencing these attitudes have a genetic, neurobiological, biochemical, affective-motivational, cognitive, and behavioral background. Another important issue addressed in the paper is a description of the mechanism leading to continuous dietary restrictions. The altered activity of neurotransmitters modulating patients’ moods after the consumption of food and a disturbed responsiveness to enterohormones enhance affective-motivational and cognitive aspects which, in turn, impede the improvement of eating behaviors. An understanding of the mechanisms behind the factors affecting the maintenance of inappropriate eating attitudes may contribute to greater effectiveness in the treatment of anorexia nervosa.

WITHDRAWN: Decreased level of endogenous ghrelin is involved in the progression of lung injury induced by oleic acid

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Energy homeostasis genes and survival after breast cancer diagnosis: the Breast Cancer Health Disparities Study

PURPOSE

The leptin-signaling pathway and other genes involved in energy homeostasis (EH) have been examined in relation to breast cancer risk as well as to obesity. We test the hypothesis that genetic variation in EH genes influences survival after diagnosis with breast cancer and that body mass index (BMI) will modify that risk.

METHODS

We evaluated associations between 10 EH genes and survival among 1,186 non-Hispanic white and 1,155 Hispanic/Native American women diagnosed with breast cancer. Percent Native American (NA) ancestry was determined from 104 ancestry-informative markers. Adaptive rank truncation product (ARTP) was used to determine gene and pathway significance.

RESULTS

The overall EH pathway was marginally significant for all-cause mortality among women with low NA ancestry (P(ARTP) = 0.057). Within the pathway, ghrelin(GHRL) and leptin receptor (LEPR) were significantly associated with all-cause mortality (P(ARTP) = 0.035 and 0.007, respectively). The EH pathway was significantly associated with breast cancer-specific mortality among women with low NA ancestry (P(ARTP) = 0.038). Three genes cholecystokinin (CCK), GHRL, and LEPR were significantly associated with breast cancer-specific mortality among women with low NA ancestry (P(ARTP) = 0.046,0.015, and 0.046, respectively), while neuropeptide Y (NPY) was significantly associated with breast cancer-specific mortality among women with higher NA ancestry(P(ARTP) = 0.038). BMI did not modify these associations.

CONCLUSIONS

Our data support our hypothesis that certain EH genes influence survival after diagnosis with breast cancer; associations appear to be most important among women with low NA ancestry.

Helicobacter pylori Infection in Children: Nutritional Status and Associations with Serum Leptin, Ghrelin, and IGF-1 Levels

BACKGROUND

Helicobacter pylori is associated with gastrointestinal diseases such as gastritis, peptic ulcers, malignancy and lymphoma, and extra-gastrointestinal conditions. H. pylori infection is negatively associated with children's growth. Chronic inflammation of the stomach that results in the loss of appetite and, dysregulation of neuroendocrine hormones such as leptin, and ghrelin are the probable reasons of this negative association. The objective of this study is to determine the serum levels of leptin, ghrelin, and IGF-1 in H. pylori-infected children and their relations with growth.

MATERIALS AND METHODS

A hundred and sixty-one school children aged between 6 and 14 years were selected randomly from five primary schools representing a cross section of population. Demographic and sociocultural characteristics, and anthropometric measurements were recorded. Serum H. pylori IgG, insulin-like growth factor-1, leptin, and ghrelin levels were measured in all children. The children were grouped according to the nutritional status and Helicobacter pylori seropositivity. Nutritional indices were compared among groups in association with serum leptin, ghrelin, and insulin-like growth factor-1 levels.

RESULTS

H. pylori IgG positivity was found in 34.2%, and 14.9% of children were malnourished. H. pylori seropositivity was significantly higher in older ages (10.32 ± 2.26 vs 9.53 ± 2.36 years, p = .036), and body weight and height Z scores were significantly lower in H. pylori-seropositive children (-0.33 ± 1.08 vs 0.04 ± 1.26, p = .044 and 0.13 ± 0.92 vs 0.23 ± 0.91, p = .018 respectively). H. pylori seropositivity was found to be an independent risk factor for shorter body height (p = .01). Serum leptin, ghrelin, and IGF-1 levels were not associated with H. pylori IgG seropositivity (0.35 vs 0.55 ng/mL, p = .3; 3267.4 ± 753.0 vs 2808.3 ± 911.4 pg/mL, p = .06; 470 ± 176 vs 521 ± 179 ng/mL, p = .32, respectively).

CONCLUSIONS

Children infected with H. pylori are prone to short stature. This effect seems to be independent of neuroendocrine hormones.

Shikonin induces apoptosis of lung cancer cells via activation of FOXO3a/EGR1/SIRT1 signaling antagonized by p300

Shikonin derivatives exert powerful cytotoxic effects including induction of apoptosis. Here, we demonstrate the cytotoxic efficacy of shikonin in vivo in xenograft models, which did not affect body weight as well as its reduction of cell viability in vitro using several non-small cell lung cancer (NSCLC) cell lines. We found that inhibition of AKT by shikonin activated the forkhead box (FOX)O3a/early growth response protein (EGR)1 signaling cascade and enhanced the expression of the target gene Bim, leading to apoptosis in lung cancer cells. Overexpression of wild-type or a constitutively active mutant of FOXO3a enhanced shikonin-induced Bim expression. The NAD⁺-dependent histone deacetylase sirtuin (SIRT)1 amplified the pro-apoptotic effect by deacetylating FOXO3a, which induced EGR1 binding to the Bim promoter and activated Bim expression. Meanwhile, PI3K/AKT activity was enhanced, whereas that of FOXO3a was reduced and p300 was upregulated by treatment with a sublethal dose of shikonin. FOXO3a acetylation was enhanced by p300 overexpression, while shikonin-induced Bim expression was suppressed by p300 overexpression, which promoted cell survival. FOXO3a acetylation was increased by p300 overexpression and treatment with SIRT1 inhibitor, improving cell survival. In addition, shikonin-induced FOXO3a nuclear localization was blocked by AKT activation and SIRT1 inhibition, which blocked Bim expression and conferred resistance to the cytotoxic effects of shikonin. The EGR1 increase induced by shikonin was restored by pretreatment with SIRT1 inhibitor. These results suggest that shikonin induces apoptosis in some lung cancer cells via activation of FOXO3a/EGR1/SIRT1 signaling, and that AKT and p300 negatively regulate this process via Bim upregulation.

Energy homeostasis genes and breast cancer risk: The influence of ancestry, body size, and menopausal status, the breast cancer health disparities study

BACKGROUND

Obesity and breast cancer risk is multifaceted and genes associated with energy homeostasis may modify this relationship.

METHODS

We evaluated 10 genes that have been associated with obesity and energy homeostasis to determine their association with breast cancer risk in Hispanic/Native American (2111 cases, 2597 controls) and non-Hispanic white (1481 cases, 1585 controls) women.

RESULTS

Cholecystokinin (CCK) rs747455 and proopiomelanocortin (POMC) rs6713532 and rs7565877 (for low Indigenous American (IA) ancestry); CCK rs8192472 and neuropeptide Y (NYP) rs16141 and rs14129 (intermediate IA ancestry); and leptin receptor (LEPR) rs11585329 (high IA ancestry) were strongly associated with multiple indicators of body size. There were no significant associations with breast cancer risk between genes and SNPs overall. However, LEPR was significantly associated with breast cancer risk among women with low IA ancestry (PARTP=0.024); POMC was significantly associated with breast cancer risk among women with intermediate (PARTP=0.015) and high (PARTP=0.012) IA ancestry. The overall pathway was statistically significant for pre-menopausal women with low IA ancestry (PARTP=0.05), as was cocaine and amphetamine regulated transcript protein (CARTPT) (PARTP=0.014) and ghrelin (GHRL) (PARTP=0.007). POMC was significantly associated with breast cancer risk among post-menopausal women with higher IA ancestry (PARTP=0.005). Three SNPs in LEPR (rs6704167, rs17412175, and rs7626141), and adiponectin (ADIPOQ); rs822391) showed significant 4-way interactions (GxExMenopausexAncestry) for multiple indicators of body size among pre-menopausal women.

CONCLUSIONS

Energy homeostasis genes were associated with breast cancer risk; menopausal status, body size, and genetic ancestry influenced this relationship.

Possible intermediary role of ghrelin in seborrhea

Seborrhea, or oily skin, is a very common condition, especially among young people, caused by the increased secretion of sebum by sebaceous glands in the skin. Based on today's knowledge, a regulatory role of various hormones especially androgens is considered for sebaceous gland secretion; but despite significant evidences emphasis on the effects of the gastrointestinal disorders on coetaneous manifestations, the role of gastrointestinal problems in sebum secretion has not been emphasized yet. This study aimed to explain hormonal changes occurring in gastroesophageal reflux disease which may cause changes in sebaceous gland secretion so that, by explaining these communication mechanisms, common investigations between gastroenterology and dermatology can be performed to evaluate the accuracy of this hypothesis.

The effect of ghrelin and estradiol on mean concentration of thyroid hormones

BACKGROUND

Ghrelin is a novel peptide hormone that has GH releasing activity and also other endocrine and metabolic functions. It can also increase food intake and decrease T3 and T4 concentrations. Several parameters of hypothalamic-pituitary-thyroid (HPT) axis function are modulated by 17β-estradiol (E2).

OBJECTIVES

The purpose of this study was to investigate the effect of interactions between ghrelin and estradiol (injected via ICV route) on plasma T3 and T4 concentrations in female rats.

MATERIALS AND METHODS

Eighteen Wistar female rats (bodyweight, 200-250 g) were randomly divided into three groups. Group 1 received estradiol, Group 2 received ghrelin and Group 3 received ghrelin and estradiol. Plasma samples were used to assess T3 and T4 concentration by RIA.

RESULTS

The results indicated that ghrelin significantly decreased thyroid hormone concentrations, whereas estradiol increased these concentrations. The simultaneous injection of ghrelin and estradiol significantly decreased the inhibitory effect of ghrelin on thyroid hormone concentrations (P < 0.05).

CONCLUSIONS

According to the results of this study, both ghrelin and estradiol affect the concentration of thyroid hormone but in opposite directions. This difference might be due to different underlying hormonal mechanisms such as HPA and/or HPT axis melanocyte stimulating hormone (MSH) systems could be suggested.

Emerging biomarkers in heart failure and cardiac cachexia

Biomarkers are objective tools with an important role for diagnosis, prognosis and therapy optimization in patients with heart failure (HF). To date, natriuretic peptides are closest to optimal biomarker standards for clinical implications in HF. Therefore, the efforts to identify and test new biomarkers in HF are reasonable and justified. Along the natural history of HF, cardiac cachexia may develop, and once at this stage, patient performance and prognosis is particularly poor. For these reasons, numerous biomarkers reflecting hormonal, inflammatory and oxidative stress pathways have been investigated, but only a few convey relevant information. The complex pathophysiology of HF appears far too complex to be embraced by a single biomarker; thus, a combined approach appears reasonable. With these considerations, we have reviewed the recent developments in the field to highlight key candidates with diagnostic, prognostic and therapy optimization properties, either alone or in combination.

Appetite loss may be induced by lower serum ghrelin and higher serum leptin concentrations in subarachnoid hemorrhage patients

BACKGROUND

Patients with aneurysmal subarachnoid hemorrhage (SAH) typically develop appetite loss. However, the mechanisms regulating appetite are not understood. Ghrelin and leptin, both of which signal nutritional status and energy storage levels to the hypothalamus, are essential elements of the appetite system. Thus, the goal of this study was to investigate the relationship between appetite and ghrelin and leptin concentrations in patients with SAH.

METHODS

Blood plasma or serum profiles and appetite status were measured in 19 patients with SAH who underwent aneurysmal clipping within 48 hours of SAH onset. Appetite status was measured using dietary oral calorie intake. All outcome variables were measured at an early (day 3) and late (day 8) time point after SAH onset (day 0).

RESULTS

Of the 19 patients studied, 6 (31.6%) showed lower dietary oral calorie intake at the late time point than at the early time point. In these patients with appetite loss, plasma hemoglobin (P < 0.02), albumin (P < 0.01), glucose (P < 0.01), plasma insulin (P < 0.04), and serum ghrelin (P < 0.03) concentrations were lower at the late time point than at the early time point. Serum leptin was higher at the late time point than at the early time point (P < 0.02).

CONCLUSION

In SAH patients, appetite loss may be induced by lower serum ghrelin and higher serum leptin concentrations resulting from high plasma glucose and insulin levels due to a catecholamine surge following SAH.

Novel therapeutic targets for sepsis: regulation of exaggerated inflammatory responses

Sepsis is a devastating and complex syndrome and continues to be a major cause of morbidity and mortality among critically ill patients at the surgical intensive care unit setting in the United States. The occurrence of sepsis and septic shock has increased significantly over the past two decades. Despite of highly dedicated basic research and numerous clinical trials, remarkable progress has not been made in the development of novel and effective therapeutics. The sepsis-induced physiologic derangements are due largely to the host responses to the invading microorganism in contrast to the direct effects of the microorganism itself. Sepsis, the systemic inflammatory response to infection, is marked by dysregulated production of pro-inflammatory cytokines. Although pro-inflammatory cytokine production is normally indispensable to protect against pathogens and promote tissue repair, the dysregulated and prolonged production of these cytokines can trigger a systemic inflammatory cascade mediated by chemokines, vasoactive amines, the complement and coagulation system, and reactive oxygen species (ROS), amongst others. These mediators collectively lead to multiple organ failure, and ultimately to death. In this regard, the role of inflammation in the pathophysiology of sepsis, although still incompletely understood, is clearly critical. Recent findings resulting from vigorous investigations have contributed to delineate various novel directions of sepsis therapeutics. Among these, this review article is focused on new promising mechanisms and concepts that could have a key role in anti-inflammatory strategies against sepsis, including 1) "inflammasome": a multiprotein complex that activates caspase-1; 2) "the cholinergic anti-inflammatory pathway": the efferent arm of the vagus nerve-mediated, brain-to-immune reflex; 3) "stem cells": unspecialized and undifferentiated precursor cells with the capacity for self-renewal and potential to change into cells of multiple lineages; 4) "milk fat globule-EGF factor VIII (MFG-E8)": a bridging molecule between apoptotic cells and phagocytes, which promotes phagocytosis of apoptotic cells.

Effect of application route of the ghrelin analog BIM-28131 (RM-131) on body weight and body composition in a rat heart failure model

Chronic heart failure (CHF) remains one of the most challenging diseases in terms of numbers and disease management, particularly so, if the CHF patient develops cardiac cachexia. Ghrelin and its analogs have been suggested to improve body weight and cardiac function in heart failure models and exploratory human clinical studies. However, most ghrelin compounds are peptides and need to be injected several times per day, which affects the quality of life of patients. Here, we compared two application routes, three times daily subcutaneous (sc) injections to continuous infusion using osmotic mini-pumps in a rat model of CHF. Moreover, the effects were also compared to three times daily sc injections of growth hormone (GH). Rats were treated for 28 d. The results show that treatment with 50 or 100 nmol/kg/d BIM-28131 (RM-131) potently induces body weight gain, fat and lean mass compared to placebo. The gain of lean mass was equal to the gain of lean mass in the 2mg/kg/d GH group and superior to 250 μg/kg/d GH. Both GH and BIM-28131 increased levels of insulin-like growth factor-1 to a similar extent. Little effect was seen on cardiac function; only cardiac output was improved by either high dose BIM-28131 or GH. Overall the effects of BIM-28131 were similar in both application routes.

Regulators of synaptic transmission: roles in the pathogenesis and treatment of epilepsy

Synaptic transmission is the communication between a presynaptic and a postsynaptic neuron, and the subsequent processing of the signal. These processes are complex and highly regulated, reflecting their importance in normal brain functioning and homeostasis. Sustaining synaptic transmission depends on the continuing cycle of synaptic vesicle formation, release, and endocytosis, which requires proteins such as dynamin, syndapin, synapsin, and synaptic vesicle protein 2A. Synaptic transmission is regulated by diverse mechanisms, including presynaptic modulators of synaptic vesicle formation and release, postsynaptic receptors and signaling, and modulators of neurotransmission. Neurotransmitters released presynaptically can bind to their postsynaptic receptors, the inhibitory γ-aminobutyric acid (GABA)ergic receptors or the excitatory glutamate receptors. Once released, glutamate activates a variety of postsynaptic receptors including α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), N-methyl-D-aspartate (NMDA), kainate, and metabotropic receptors. The activation of the receptors triggers downstream signaling cascades generating a vast array of effects, which can be modulated by a numerous auxiliary regulatory subunits. Moreover, different neuropeptides such as neuropeptide Y, brain-derived neurotrophic factor (BDNF), somatostatin, ghrelin, and galanin, act as regulators of diverse synaptic functions and along with the classic neurotransmitters. Abnormalities in the regulation of synaptic transmission play a critical role in the pathogenesis of numerous brain diseases, including epilepsy. This review focuses on the different mechanisms involved in the regulation of synaptic transmission, which may play a role in the pathogenesis of epilepsy: the presynaptic modulators of synaptic vesicle formation and release, postsynaptic receptors, and modulators of neurotransmission, including the mechanism by which drugs can modulate the frequency and severity of epileptic seizures.

The relation between peptide hormones and sex hormone in patients with multiple sclerosis

BACKGROUND

Hormones can play a significant role in the pathogenesis of multiple sclerosis (MS). The aim of this study was to compare levels of ghrelin, leptin, and testosterone hormones of MS patients with healthy subjects, and assess the relationship between levels of peptide hormone and sex hormones in MS patients.

METHODS

35 MS patients with definite relapsing remitting multiple sclerosis (RRMS) (male = 9, female = 26) and 13 healthy subjects (male = 4, female = 9) were enrolled in the study. Levels of serum ghrelin, leptin, and testosterone hormones were measured in this study. ANOVA and Pearson correlation were used for data analysis (P < 0.05).

RESULTS

The female and male participants of the patient group were compared with the healthy group. No significant differences were found in serum of leptin, ghrelin, testosterone, ghrelin/leptin, and testosterone/leptin (P < 0.05). Spearman correlation coefficient showed that leptin had a significant negative correlation with the variability of testosterone (r = -1.00) in the healthy male group. Moreover, leptin had a significant positive correlation with the variability of BMI (r = 0.68) and weight (r = 0.59), at the 0.01 level (2-tailed), in the female patient group. In addition, in the healthy male group, ghrelin had a significant negative correlation with the variability of weight (r = -1.00).

CONCLUSION

According to the results, there was no significant difference between peptide and sex hormones of MS patients and healthy persons. Furthermore, there was no significant relationship between peptide and sex hormones of MS patients and healthy persons.

Effects of ghrelin on pulmonary NOD2 mRNA expression and NF-κB activation when protects against acute lung injury in rats challenged with cecal ligation and puncture

BACKGROUND

Many studies have shown that ghrelin can down-regulate inflammatory cytokine expression via the inhibition of NF-κB activity and therefore, its administration to septic patients is considered beneficial. However, our knowledge of ghrelin's effects on the upstream activators of the NF-κB pathway, such as NOD2, is still limited. This study aimed to investigate the possible involvement of the NOD2 signaling pathway in the anti-inflammatory effects of ghrelin.

METHODS

Twenty-four male SD rats received cecal ligation and puncture (CLP) or sham operation, followed by infusion of saline or ghrelin. The lungs were harvested 6h after CLP or sham operation and analyzed for lung histopathology, neutrophil infiltration, inflammatory cytokines (TNF-α, and IL-6), NOD2 mRNA expression, and activation of NF-κB. Furthermore, survival was recorded for ten days in additional groups of rats.

RESULTS

Compared with sham group, neutrophil infiltration, TNF-α and IL-6 levels, NOD2 mRNA expression, as well as NF-κB activation in lungs from rats undergoing CLP were significantly increased. After the administration of ghrelin, all inflammatory parameters analyzed were lower than those without ghrelin following CLP. In addition, ghrelin improved survival after CLP.

CONCLUSION

Our results indicate that in a CLP model of sepsis, the beneficial effects that ghrelin has on inflammatory outcomes are mediated at least in part through inhibition of NOD2 expression upstream of NF-κB.

Protocol for the modeling the epidemiologic transition study: a longitudinal observational study of energy balance and change in body weight, diabetes and cardiovascular disease risk

BACKGROUND

The prevalence of obesity has increased in societies of all socio-cultural backgrounds. To date, guidelines set forward to prevent obesity have universally emphasized optimal levels of physical activity. However there are few empirical data to support the assertion that low levels of energy expenditure in activity is a causal factor in the current obesity epidemic are very limited.

METHODS/DESIGN

The Modeling the Epidemiologic Transition Study (METS) is a cohort study designed to assess the association between physical activity levels and relative weight, weight gain and diabetes and cardiovascular disease risk in five population-based samples at different stages of economic development. Twenty-five hundred young adults, ages 25-45, were enrolled in the study; 500 from sites in Ghana, South Africa, Seychelles, Jamaica and the United States. At baseline, physical activity levels were assessed using accelerometry and a questionnaire in all participants and by doubly labeled water in a subsample of 75 per site. We assessed dietary intake using two separate 24-hour recalls, body composition using bioelectrical impedance analysis, and health history, social and economic indicators by questionnaire. Blood pressure was measured and blood samples collected for measurement of lipids, glucose, insulin and adipokines. Full examination including physical activity using accelerometry, anthropometric data and fasting glucose will take place at 12 and 24 months. The distribution of the main variables and the associations between physical activity, independent of energy intake, glucose metabolism and anthropometric measures will be assessed using cross-section and longitudinal analysis within and between sites.

DISCUSSION

METS will provide insight on the relative contribution of physical activity and diet to excess weight, age-related weight gain and incident glucose impairment in five populations' samples of young adults at different stages of economic development. These data should be useful for the development of empirically-based public health policy aimed at the prevention of obesity and associated chronic diseases.

Human ghrelin protects animals from renal ischemia-reperfusion injury through the vagus nerve

BACKGROUND

Acute kidney injury secondary to renal ischemia and reperfusion injury is widely prevalent. Ghrelin, which is a stomach-derived peptide, has been shown to be anti-inflammatory. The purpose of this study was to examine whether human ghrelin has any beneficial effects after renal ischemia and reperfusion injury, and if so, whether ghrelin's action in renal ischemia and reperfusion injury is mediated by the vagus nerve.

METHODS

Male adult rats were subjected to renal ischemia and reperfusion by bilateral renal pedicle clamping for 60 min, treated intravenously with human ghrelin (4 nmol/rat) or normal saline (vehicle) immediately after reperfusion. After 24 h, the animals were killed and samples were harvested. In separate groups, subdiaphragmatic vagotomy prior to renal ischemia and reperfusion was performed, treated with human ghrelin or vehicle, and at 24 h, blood and organs were harvested.

RESULTS

Renal ischemia and reperfusion injury caused significant increases in the serum levels of tissue injury markers compared with the sham operation. Human ghrelin treatment attenuated serum creatinine and blood urea nitrogen significantly by 55% and 53%, and liver enzymes (aminotransferase [AST] and alanine aminotransferase [ALT]) by 20% and 24%, respectively, compared with the vehicle-treated groups. Tissue water contents, plasma and kidney interleukin-6, and kidney myeloperoxidase activity were decreased. Bcl-2/Bax ratio was increased, and histology of the kidneys was improved. More importantly, prior vagotomy abolished ghrelin's protective effect in tissue injury markers and tissue water contents in renal ischemia and reperfusion injured animals.

CONCLUSION

Human ghrelin treatment in renal ischemia and reperfusion injured rats attenuated systemic and kidney-specific inflammatory responses. The protection of human ghrelin in renal ischemia and reperfusion injury was mediated by the vagus nerve. These data suggest that ghrelin can be developed as a novel treatment for patients with acute kidney injury induced by renal ischemia and reperfusion injury.

Voluntary exercise attenuates obesity-associated inflammation through ghrelin expressed in macrophages

Chronic low-level inflammation is associated with obesity and a sedentary lifestyle, causing metabolic disturbances such as insulin resistance. Exercise training has been shown to decrease chronic low-level systemic inflammation in high-fat diet (HFD)-induced obesity. However, the molecular mechanisms mediating its beneficial effects are not fully understood. Ghrelin is a peptide hormone predominantly produced in the stomach that stimulates appetite and induces growth hormone release. In addition to these well-known functions, recent studies suggest that ghrelin localizes to immune cells and exerts an anti-inflammatory effect. The purpose of the current study was to investigate the role of ghrelin expressed in macrophages in the anti-inflammatory effects of voluntary exercise training. Expression of tumor necrosis factor-α (TNF-α), monocyte chemotactic protein (MCP)-1 and F4/80 was increased in adipose tissue from mice fed a HFD (HFD mice) compared with mice fed a standard diet (SD mice), whereas the expression of these inflammatory cytokines was markedly decreased in mice performing voluntary wheel running during the feeding of a HFD (HFEx mice). The expression of TNF-α was also increased in peritoneal macrophages by a HFD and exercise training inhibited the increase of TNF-α expression. Interestingly, expression of ghrelin in peritoneal macrophages was decreased by a HFD and recovered by exercise training. Suppression of ghrelin expression by siRNA increased TNF-α expression and LPS-stimulated NF-κB activation in RAW264 cells, which is a macrophage cell line. TNF-α expression by stimulation with LPS was significantly suppressed in RAW264 cells cultured in the presence of ghrelin. These results suggest that ghrelin exerts potent anti-inflammatory effects in macrophages and functions as a mediator of the beneficial effects of exercise training.

Randomised clinical trial: Helicobacter pylori eradication is associated with a significantly increased body mass index in a placebo-controlled study

BACKGROUND

Body mass index (BMI) increased following Helicobacter pylori eradication in several Japanese cohorts, which requires further investigation.

AIM

To determine the impact of H. pylori eradication on BMI in a European population.

METHODS

A total of 10,537 unselected people aged 20-59 years were screened for H. pylori; 1558 of the 1634 infected participants were randomised to intervention (eradication therapy: ranitidine bismuth citrate 400 mg and clarithromycin 500 mg twice daily) or placebo for 2 weeks with follow-up at 6 months (92%) for weight and dyspepsia symptoms (epigastric pain).

RESULTS

The mean weight of participants in the intervention group increased from 77.7 kg at baseline to 78.4 kg at 6 months (unadjusted increase of 0.7 kg) and from 76.8 to 77.2 kg (0.5 kg) in the placebo group. The adjusted difference between randomised groups was statistically significant at 0.6 kg [95% confidence interval (CI) 0.31, 0.88]. Significantly, more participants gained ≥3 kg in the intervention group (138/720, 19%) compared with the placebo group (92/706, 13%) [odds ratio (OR) 1.57 (95% CI: 1.17, 2.12)]. The mean BMI increased from 27.5 to 27.8 kg/m(2) at 6 months in the intervention group compared with the increase from 27.0 to 27.2 kg/m(2) in the placebo group [adjusted difference between groups was statistically significant at 0.2 kg/m(2) (95% CI: 0.11, 0.31)]. Dyspepsia was less frequently reported by intervention group participants (168/736, 23%, placebo group 209/711, 29%), OR 0.71 (95% CI: 0.55, 0.93).

CONCLUSION

Body mass index increased significantly following randomisation to H. pylori eradication therapy, possibly due to resolution of dyspepsia.

Vitamins B status and antioxidative defense in patients with chronic hepatitis B or hepatitis C virus infection

BACKGROUND & AIMS

The impact of hepatitis B virus (HBV) or hepatitis C virus (HCV) infection upon B vitamins status and antioxidative defense in infected patients was examined.

METHODS

Dietary record and blood levels of B vitamins and oxidative stress-associated biomarkers were determined for 195 healthy controls, 132 HBV, and 114 HCV patients.

RESULTS

HBV-infected patients had significantly higher levels of total cholesterol, free fatty acids (FFA), and lower ghrelin level (p < 0.05); and HCV-infected patients had significantly higher Ishak inflammation score and lactate dehydrogenase activity (p < 0.05). HBV patients had significantly lower red blood cell (RBC) vitamins B(2) and B(6) levels, and HCV infection significantly decreased vitamins B(2,) B(6) and folate levels in RBC and/or plasma (p < 0.05). Correlation coefficients of RBC vitamin B(2) versus serum FFA in HBV patients, RBC vitamins B(2) and B(6) versus HCV RNA and Ishak inflammation score, and plasma vitamin B(6) vs Ishak inflammation score in HCV patients were <-0.5. HBV-infected patients had significantly higher oxidized glutathione level and lower glutathione peroxidase activity (p < 0.05), but HCV patients had significantly lower superoxide dismutase and catalase activities (p < 0.05).

CONCLUSION

HBV or HCV infection enhanced oxidative stress and lowered B vitamins in circulation. In order to avoid other healthy risk, nutrition status should be monitored and limitation or supplementation of certain nutrients might be helpful for HBV- or HCV-infected patients.

Diet, exercise and gut mucosal immunity

Diet and exercise are primary strategies recommended for the control of the obesity epidemic. Considerable attention is being paid to the effect of both on the immune system. However, little research has been done on the effect of diet, nutrients or exercise on the mucosal immune system. The gastrointestinal tract (gut) is not only responsible for the entry of nutrients into the organism, but also for triggering the primary immune response to orally ingested antigens. The gut-associated lymphoid tissue contains a large amount of immune cells, disseminated all along the intestine in Peyer's patches and lamina propria. Specific nutrients or their combinations, as well as the microflora, are capable of modulating the immune system through cell activation, production of signalling molecules or gene expression. We have observed an increase in T-cells as well as a decrease in B-cells from Peyer's patches, induced by diets high in fats or carbohydrates in Balb/c mice. It has also been demonstrated that exercise modulates the immune system, where moderate levels may improve its function by increasing the proliferation of lymphocytes from various sites, including gut-associated lymphoid tissue, whereas exhaustive acute exercise may cause immunosuppression. High-fat diets combined with exercise are able to induce an increase in CD3+ lymphocytes due to increased CD8+ cells and a decrease in B-cells. Explanations and consequences of the effects of diet and exercise on the gut mucosal immunity are still being explored.

Ghrelin decreases microvascular leak during inflammation

BACKGROUND

Obesity is a risk factor for poor outcomes after trauma, and circulating levels of ghrelin are decreased in obese patients. We hypothesized that ghrelin modifies microvascular permeability. The purposes of this study were to determine (1) the effect of ghrelin on microvascular permeability, (2) the effect of ghrelin on microvascular permeability during lipopolysaccharide (LPS)-induced inflammation, (3) the involvement of the growth hormone secretagogue receptor (GHS-R1a) cell receptor, and (4) the involvement of nuclear factor kappa B (NF-kappaB).

METHODS

Hydraulic permeability (Lp), a measure of transendothelial fluid leak, was measured in rat mesenteric postcapillary venules. Lp was measured during continuous administration of (1) ghrelin (3 micromol/L), (2) ghrelin and systemic LPS (10 mg/kg), (3) the GHS-R1a receptor antagonist, (D-Arg1 D-Phe5 D-Trp7,9 Leu11)-substance P (9 micromol/L) plus ghrelin and LPS, and (4) an NF-kappaB inhibitor, parthenolide (10 micromol/L) plus ghrelin and LPS.

RESULTS

Ghrelin alone had no effect (p > 0.7). Compared with LPS alone, ghrelin plus LPS decreased Lp (Lp: ghrelin + LPS = 1.60 +/- 0.16 vs. LPS = 2.27 +/- 0.14, p < 0.006). The GHS-R1a ghrelin receptor antagonist blunted the effect of ghrelin by 86% during LPS-induced inflammation (Lp: ghrelin + LPS = 1.60 +/- 0.16 vs. ghrelin antagonist + ghrelin + LPS = 2.17 +/- 0.27, p < 0.018). NF-kappaB inhibition did not influence the initial increased microvascular leak effect of ghrelin (p > 0.8).

CONCLUSIONS

Although ghrelin has no effect on basal microvascular permeability, it has a biphasic effect with an overall decrease in microvascular permeability during LPS-induced inflammation through the GHS-R1a receptor, independent of NF-kappaB. Ghrelin is a key mediator of inflammation and may contribute to the increased morbidity and mortality in obese trauma patients.

Ghrelin: a potential therapeutic target for cancer

Ghrelin is a recently identified 28-amino-acid peptide, capable of stimulating pituitary growth hormone release in humans and other mammals. It is mainly secreted from the gastric mucosa, but it is also widely expressed in a variety of tissues, in both normal and malignant conditions. Ghrelin has a multiplicity of physiological functions in gastrointestinal, cardiovascular, pulmonary and immune system, and also exerts a variety of roles, from increasing food intake (orexigenic effect) to affecting cell proliferation. The actions of ghrelin are mediated by the ghrelin receptor, also known as the growth hormone secretagogue receptor (GHS-R). The purpose of this review is to provide an overview of the expression and putative role of ghrelin and its receptor in cancer. Ghrelin and its receptor are detected in tumor tissues, and evidence is emerging that ghrelin plays an autocrine/paracrine role in cancer and could serve as a diagnostic or prognostic tool or as therapeutic target.

Inhibition of Foxo1 mediates protective effects of ghrelin against lipotoxicity in MIN6 pancreatic beta-cells

Ghrelin is a 28-amino-acid peptide secreted predominantly by X/A-like cells of the gastric fundus. Ghrelin increases pancreatic beta-cell proliferation and survival via sequential activation of phosphatidylinositol-3 kinase (PI3K) and Akt. The transcription regulator Foxo1 is a prominent effector of PI3K/Akt; when it is inhibited, pancreatic beta-cells are protected against fatty-acid-induced apoptosis. We investigated the role of Foxo1 in the protective effect of ghrelin under lipotoxic conditions in the MIN6 pancreatic beta-cell line. Results showed that ghrelin promoted cell proliferation and attenuated palmitate-induced apoptosis in cultured MIN6 cells. Nuclear exclusion of Foxo1 was necessary for the function of ghrelin. Treatment of MIN6 cells with palmitate and ghrelin-induced rapid nuclear exclusion and phosphorylation of Foxo1. Unlike the JNK inhibitor SP600125, Akt inhibitor IV blocked the anti-lipotoxic effect of ghrelin and stimulated Foxo1 nuclear translocation. In addition, treatment with ghrelin combined with SP600125 showed a synergistic antiapoptotic effect in palmitate-treated MIN6 cells. Ghrelin also inhibited the endoplasmic reticulum stress pathway of apoptosis in MIN6 cells, decreased expression of cytoplasmic triglyceride, and downregulated gene expression of Bcl-2-associated X (BAX), sterol-response element-binding protein 1c (SREBP1c), and C/EBP homologous protein (CHOP-10). These findings suggest that ghrelin protects pancreatic beta-cells from lipotoxicity by inhibiting the nuclear translocation of Foxo1.