Serum ghrelin levels and risk of subsequent adenocarcinoma of the esophagus

Genome-Wide Association and Two-Sample Mendelian Randomization Analyses of Plasma Ghrelin and Gastrointestinal Cancer Risk

BACKGROUND

Observational studies have suggested that the gut hormone ghrelin is an early marker of future risk of developing gastrointestinal cancer. However, whether ghrelin is a causal risk factor remains unclear. We conducted a genome-wide association study (GWAS) of plasma ghrelin and used Mendelian randomization (MR) to investigate the possible causal association between ghrelin and gastrointestinal cancer risk.

METHODS

Genetic variants associated with plasma ghrelin were identified in a GWAS comprising 10,742 Swedish adults in the discovery (N = 6,259) and replication (N = 4,483) cohorts. The association between ghrelin and gastrointestinal cancer was examined through a two-sample MR analysis using the identified genetic variants as instruments and GWAS data from the UK Biobank, FinnGen, and a colorectal cancer consortium.

RESULTS

GWAS found associations between multiple genetic variants within ±200 kb of the GHRL gene and plasma ghrelin. A two-sample MR analysis revealed that genetically predicted higher plasma ghrelin levels were associated with a lower risk of gastrointestinal cancer in UK Biobank and in a meta-analysis of the UK Biobank and FinnGen studies. The combined OR per approximate doubling of genetically predicted plasma ghrelin was 0.91 (95% confidence interval, 0.85-0.99; P = 0.02). Colocalization analysis revealed limited evidence of shared causal variants for plasma ghrelin and gastrointestinal cancer at the GHRL locus (posterior probability H4 = 24.5%); however, this analysis was likely underpowered.

CONCLUSIONS

Our study provides evidence in support of a possible causal association between higher plasma ghrelin levels and a reduced risk of gastrointestinal cancer.

IMPACT

Elevated plasma ghrelin levels might reduce the risk of gastrointestinal cancer.

Ghrelin and its role in gastrointestinal tract tumors (Review)

Ghrelin, an orexigenic hormone, is a peptide that binds to the growth hormone secretagogue receptor; it is secreted mainly by enteroendocrine cells in the oxyntic glands of the stomach. Ghrelin serves a role in both local and systemic physiological processes, and is implicated in various pathologies, including neoplasia, with tissue expression in several types of malignancies in both in vitro and in vivo studies. However, the precise implications of the ghrelin axis in metastasis, invasion and cancer progression regulation has yet to be established. In the case of gastrointestinal (GI) tract malignancies, ghrelin has shown potential to become a prognostic factor or even a therapeutic target, although data in the literature are inconsistent and unsystematic, with reports untailored to a specific histological subtype of cancer or a particular localization. The evaluation of immunohistochemical expression shows a limited outlook owing to the low number of cases analyzed, and in vivo analyses have conflicting data regarding differences in ghrelin serum levels in patients with cancer. The aim of this review was to examine the relationship between ghrelin and GI tract malignancies to demonstrate the inconsistencies in current results and to highlight its clinical significance in the outcome of these patients.

Body size and composition and risk of site-specific cancers in the UK Biobank and large international consortia: A mendelian randomisation study

BACKGROUND

Evidence for the impact of body size and composition on cancer risk is limited. This mendelian randomisation (MR) study investigates evidence supporting causal relationships of body mass index (BMI), fat mass index (FMI), fat-free mass index (FFMI), and height with cancer risk.

METHODS AND FINDINGS

Single nucleotide polymorphisms (SNPs) were used as instrumental variables for BMI (312 SNPs), FMI (577 SNPs), FFMI (577 SNPs), and height (293 SNPs). Associations of the genetic variants with 22 site-specific cancers and overall cancer were estimated in 367,561 individuals from the UK Biobank (UKBB) and with lung, breast, ovarian, uterine, and prostate cancer in large international consortia. In the UKBB, genetically predicted BMI was positively associated with overall cancer (odds ratio [OR] per 1 kg/m2 increase 1.01, 95% confidence interval [CI] 1.00-1.02; p = 0.043); several digestive system cancers: stomach (OR 1.13, 95% CI 1.06-1.21; p < 0.001), esophagus (OR 1.10, 95% CI 1.03, 1.17; p = 0.003), liver (OR 1.13, 95% CI 1.03-1.25; p = 0.012), and pancreas (OR 1.06, 95% CI 1.01-1.12; p = 0.016); and lung cancer (OR 1.08, 95% CI 1.04-1.12; p < 0.001). For sex-specific cancers, genetically predicted elevated BMI was associated with an increased risk of uterine cancer (OR 1.10, 95% CI 1.05-1.15; p < 0.001) and with a lower risk of prostate cancer (OR 0.97, 95% CI 0.94-0.99; p = 0.009). When dividing cancers into digestive system versus non-digestive system, genetically predicted BMI was positively associated with digestive system cancers (OR 1.04, 95% CI 1.02-1.06; p < 0.001) but not with non-digestive system cancers (OR 1.01, 95% CI 0.99-1.02; p = 0.369). Genetically predicted FMI was positively associated with liver, pancreatic, and lung cancer and inversely associated with melanoma and prostate cancer. Genetically predicted FFMI was positively associated with non-Hodgkin lymphoma and melanoma. Genetically predicted height was associated with increased risk of overall cancer (OR per 1 standard deviation increase 1.09; 95% CI 1.05-1.12; p < 0.001) and multiple site-specific cancers. Similar results were observed in analyses using the weighted median and MR-Egger methods. Results based on consortium data confirmed the positive associations between BMI and lung and uterine cancer risk as well as the inverse association between BMI and prostate cancer, and, additionally, showed an inverse association between genetically predicted BMI and breast cancer. The main limitations are the assumption that genetic associations with cancer outcomes are mediated via the proposed risk factors and that estimates for some lower frequency cancer types are subject to low precision.

CONCLUSIONS

Our results show that the evidence for BMI as a causal risk factor for cancer is mixed. We find that BMI has a consistent causal role in increasing risk of digestive system cancers and a role for sex-specific cancers with inconsistent directions of effect. In contrast, increased height appears to have a consistent risk-increasing effect on overall and site-specific cancers.

Exploration of the role of serum ghrelin in the diagnosis and treatment of digestive tract malignancies

Objective

The incidence of digestive tract malignancies (DTMs) is increasing, early diagnosis is limited, and treatment effects are unsatisfactory. DTMs express ghrelin, which might be involved in tumor formation and development; whether serum ghrelin can provide useful guidance remains unknown.

Methods

Sera of healthy individuals were obtained from October 2017 through March 2018; serum samples from patients with gastric (GC), colon (CC), and rectal (RC) cancers were collected during the same period. Serum ghrelin was tested by ELISA and correlated with clinicopathology of patients with DTMs.

Results

Serum ghrelin was higher in patients (GC, 38 patients; CC, 24; RC, 26) than in 69 healthy individuals and decreased significantly after tumor resection. Nutrition Risk Screening 2002 score and neutrophil:lymphocyte ratio affected perioperative serum ghrelin levels. The epithelial cell marker AE1/AE3 (pan keratin) in patients with GC, tumor location in the colon in patients with CC, and age in patients with RC also affected perioperative serum ghrelin.

Conclusions

Serum ghrelin might provide early warning of occurrence and guide prognosis of DTMs. Ghrelin can be used when screening for nutritional risk and inflammation. The clinicopathological influence on serum ghrelin in patients with DTMs is related to tumor location in the digestive tract.

Helicobacter pylori Related Diseases and Osteoporotic Fractures (Narrative Review)

Osteoporosis (OP) and osteoporotic fractures (OFs) are common multifactorial and heterogenic disorders of increasing incidence. Helicobacter pylori (H.p.) colonizes the stomach approximately in half of the world's population, causes gastroduodenal diseases and is prevalent in numerous extra-digestive diseases known to be associated with OP/OF. The studies regarding relationship between H.p. infection (HPI) and OP/OFs are inconsistent. The current review summarizes the relevant literature on the potential role of HPI in OP, falls and OFs and highlights the reasons for controversies in the publications. In the first section, after a brief overview of HPI biological features, we analyze the studies evaluating the association of HPI and bone status. The second part includes data on the prevalence of OP/OFs in HPI-induced gastroduodenal diseases (peptic ulcer, chronic/atrophic gastritis and cancer) and the effects of acid-suppressive drugs. In the next section, we discuss the possible contribution of HPI-associated extra-digestive diseases and medications to OP/OF, focusing on conditions affecting both bone homeostasis and predisposing to falls. In the last section, we describe clinical implications of accumulated data on HPI as a co-factor of OP/OF and present a feasible five-step algorithm for OP/OF risk assessment and management in regard to HPI, emphasizing the importance of an integrative (but differentiated) holistic approach. Increased awareness about the consequences of HPI linked to OP/OF can aid early detection and management. Further research on the HPI-OP/OF relationship is needed to close current knowledge gaps and improve clinical management of both OP/OF and HPI-related disorders.

IS THERE A RELATION BETWEEN HELYBACTER PYLORI AND INTESTINAL METAPLASIA IN SHORT COLUMN EPITELIZATION UP TO 10 MM IN THE DISTAL ESOPHAGUS?

Background:

The presence of intestinal metaplasia in the distal esophagus (Barrett’s esophagus) is an important precursor of adenocarcinoma. Knowledge of the risk factors and the process by which the Barrett develops is very important and Helicobacter pylori (HP) can contribute to this development.

Aim:

To analyze the impact of HP in the gastric mucosa with intestinal metaplasia in the distal esophagus in areas of columnar epithelialization smaller than 10 mm in length and epidemiological data on prevalence

Method:

A retrospective study in which were included 373 consecutive patients diagnosed with columnar epithelium in the distal esophagus was done. In all, HP was investigated by urease and histology, exclusion and inclusion factors were applied and patients were divided into two groups: the first grouping the ones without histological diagnosis of Barrett’s esophagus (235-63%) and the second with it (138-37%).

Results:

There was no significant difference between HP and non-HP patients in relation to the probability of having intestinal metaplasia (p=0.587). When related to the general group, there was an inverse association between the bacterium and the columnar epithelia in the distal esophagus. Age (p=0.031), gender (p=0.013) and HP (p=0.613) when related together to intestinal metaplasia showed no significant relation. In isolation, when related to age and gender, regardless of HP, results confirmed that patients in more advanced age and women present a higher incidence of intestinal metaplasia.

Conclusion:

There is an inverse relation between HP and the areas of columnar epithelization in the distal esophagus, regardless of the presence or absence of intestinal metaplasia. Age and gender, regardless of HP, showed higher prevalence in women and in older the number of cases with intestinal metaplasia in the distal esophagus.

Attribution of Ghrelin to Cancer; Attempts to Unravel an Apparent Controversy

Ghrelin is an endogenous peptide hormone mainly produced in the stomach. It has been known to regulate energy homeostasis, stimulate secretion of growth hormone, and mediate many other physiologic effects. Various effects attributed to ghrelin contribute to many aspects of cancer development and progression. Accordingly, a large body of evidence has emerged about the association of ghrelin with several types of cancer in scales of cell-line, animal, and human studies. However, existing data are controversial. This controversy occurs in two main domains: one is the controversial results in local effects of ghrelin on different types of human cancer cell-lines; the second is the apparent disagreement in the results of in-vitro and clinical studies that investigated ghrelin association to one type of cancer. These inconsistencies have hampered the indications to consider ghrelin as a potential tumor biomarker or therapeutic agent in cancer patients. Previous studies have reviewed different parts of current literature about the ghrelin-cancer relationship. Although they have highlighted these controversial results in various ways, no specific recommendations have been given to address it. In this study, we comprehensively reviewed in-vitro, in-vivo, and clinical studies and attempted to use the following approaches to unravel the inconsistencies detected: (a) to distinguish local and systemic effects of ghrelin in interpreting its summary clinical role in each cancer; (b) scrutinizing factors that regulate local effects of ghrelin and could justify different effects of ghrelin on different cancer cell-lines. These approaches could have notable implications for future in-vitro and clinical studies.

Serum ghrelin and esophageal and gastric cancer in two cohorts in China

Ghrelin is a hormone produced in the oxyntic glands of the stomach. Previous work by our group has suggested that serum ghrelin concentrations are inversely associated with gastric and esophageal cancer risk. We measured ghrelin concentrations in the Linxian General Population Nutrition Intervention Trial (NIT), and the Shanghai Women's Health Study (SWHS). In NIT, we analyzed serum samples from 298 esophageal squamous cell carcinoma (ESCC) cases, 518 gastric cardia adenocarcinoma (GCA) cases, 258 gastric noncardia adenocarcinoma (GNCA) cases and 770 subcohort controls (case-cohort). In SWHS, we measured ghrelin in plasma samples from 249 GNCA cases and 498 matched controls (nested case-control). Ghrelin was measured using radioimmunoassay. In NIT and SWHS, low ghrelin concentrations were associated with an increased risk of developing GNCA and GCA. The hazard ratio (HR _Q1:Q4 ) for GNCA in NIT was 1.35 (95% CI: 0.89-2.05; p-trend = 0.02); the odds ratio in SWHS was 1.66 (95% CI: 1.02-2.70; p-trend = 0.06). Low ghrelin was associated with a twofold increase of GCA (HR _Q1:Q4 = 2.00, 95% CI: 1.45-2.77; p-trend<0.001). In contrast, a lower risk of ESCC (NIT ESCC HR _Q1:Q4 = 0.65, 95% CI: 0.45-0.92; p-trend = 0.02) was found in NIT. Low baseline ghrelin concentrations were associated with an increased risk for GNCA and GCA in the NIT and the SWHS. In contrast, low ghrelin concentrations at baseline were associated with a reduced risk of developing ESCC in the NIT. Ghrelin may be an early marker of future cancer risk for developing upper gastrointestinal cancer in regions of high incidence.

Energy balance and gastrointestinal cancer: risk, interventions, outcomes and mechanisms

Obesity increases the risk of multiple gastrointestinal cancers and worsens disease outcomes. Conversely, strong inverse associations have emerged between physical activity and colon cancer and possibly other gastrointestinal malignancies. The effect of weight loss interventions - such as modifications of diet and/or physical activity or bariatric surgery - remains unclear in patients who are obese and have gastrointestinal cancer, although large clinical trials are underway. Human intervention studies have already shed light on potential mechanisms underlying the energy balance-cancer relationship, with preclinical models supporting emerging pathway effects. Central to interventions that reduce obesity or increase physical activity are pluripotent cancer-preventive effects (including reduced systemic and adipose tissue inflammation and angiogenesis, altered adipokine levels and improved insulin resistance) that directly interface with the hallmarks of cancer. Other mechanisms, such as DNA repair, oxidative stress and telomere length, immune function, effects on cancer stem cells and the microbiome, could also contribute to energy balance effects on gastrointestinal cancers. Although some mechanisms are well understood (for instance, systemic effects on inflammation and insulin signalling), other areas remain unclear. The current state of knowledge supports the need to better integrate mechanistic approaches with preclinical and human studies to develop effective, personalized diet and exercise interventions to reduce the burden of obesity on gastrointestinal cancer.

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 Role of Adipokines in the Establishment and Progression of Head and Neck Neoplasms

Adipokines constitute a family of protein factors secreted by white adipose tissue (WAT), that regulate the functions of WAT and other sites. Leptin, adiponectin and resistin, are the main adipokines present in serum and saliva, targeting several tissues and organs, including vessels, muscles, liver and pancreas. Besides body mass regulation, adipokines affect glucose homeostasis, inflammation, angiogenesis, cell proliferation and apoptosis, and other crucial cell procedures. Their involvement in tumor formation and growth is well established and deregulation of adipokine and adipokine receptors' expression is observed in several malignancies including those located in the head and neck region. Intracellular effects of adipokines are mediated by a plethora of receptors that activate several signaling cascades including Janus kinase/ Signal transducer and activator of transcription (JAK/ STAT pathway), Phospatidylinositol kinase (PI3/ Akt/ mTOR) and Peroxisome proliferator-activated receptor (PPAR). The present review summarizes the current knowledge on the role of adipokines family members in carcinogenesis of the head and neck region. The diagnostic and prognostic significance of adipokines and their potential role as serum and saliva biomarkers are also discussed.

Blood biomarkers for early diagnosis of oesophageal cancer: a systematic review

BACKGROUND

Oesophageal cancer prognosis remains poor owing to the inability to detect the disease at an early stage. Nontissue (serum, urinary or salivary) biomarkers potentially offer less invasive methods to aid early detection of oesophageal cancer. We aimed to systematically review studies assessing the relationship between nontissue biomarkers and subsequent development of oesophageal cancer.

METHODS

Using terms for biomarkers and oesophageal cancer, Medline, EMBASE and Web of Science were systematically searched for longitudinal studies, published until April 2016, which assessed the association between nontissue biomarkers and subsequent oesophageal cancer risk. Random effects meta-analyses were used to calculate pooled relative risk (RR) and 95% confidence intervals (CIs), where possible.

RESULTS

A total of 39 studies were included. Lower serum pepsinogen I concentrations were associated with an increased risk of oesophageal squamous cell carcinoma (n=3 studies, pooled RR=2.20, 95% CI: 1.31-3.70). However, the association for the pepsinogen I : II ratio was not statistically significant (n=3 studies, pooled RR=2.22, 95% CI: 0.77-6.40), with a large degree of heterogeneity observed (I=68.0%). Higher serum glucose concentrations were associated with a modestly increased risk of total oesophageal cancer (n=3 studies, pooled RR=1.27, 95% CI: 1.02-1.57). No association was observed for total cholesterol and total oesophageal cancer risk (n=3 studies, pooled RR=0.95, 95% CI: 0.58-1.54). Very few studies have assessed other biomarkers for meta-analyses.

CONCLUSION

Serum pepsinogen I concentrations could aid early detection of oesophageal squamous cell carcinoma. More prospective studies are needed to determine the use of other nontissue biomarkers in the early detection of oesophageal cancer.

Inverse Association Between Gluteofemoral Obesity and Risk of Barrett's Esophagus in a Pooled Analysis

BACKGROUND & AIMS

Gluteofemoral obesity (determined by measurement of subcutaneous fat in the hip and thigh regions) could reduce risks of cardiovascular and diabetic disorders associated with abdominal obesity. We evaluated whether gluteofemoral obesity also reduces the risk of Barrett's esophagus (BE), a premalignant lesion associated with abdominal obesity.

METHODS

We collected data from non-Hispanic white participants in 8 studies in the Barrett's and Esophageal Adenocarcinoma Consortium. We compared measures of hip circumference (as a proxy for gluteofemoral obesity) from cases of BE (n = 1559) separately with 2 control groups: 2557 population-based controls and 2064 individuals with gastroesophageal reflux disease (GERD controls). Study-specific odds ratios (ORs) and 95% confidence intervals (95% CIs) were estimated using individual participant data and multivariable logistic regression and combined using a random-effects meta-analysis.

RESULTS

We found an inverse relationship between hip circumference and BE (OR per 5-cm increase, 0.88; 95% CI, 0.81-0.96), compared with population-based controls in a multivariable model that included waist circumference. This association was not observed in models that did not include waist circumference. Similar results were observed in analyses stratified by frequency of GERD symptoms. The inverse association with hip circumference was statistically significant only among men (vs population-based controls: OR, 0.85; 95% CI, 0.76-0.96 for men; OR, 0.93; 95% CI, 0.74-1.16 for women). For men, within each category of waist circumference, a larger hip circumference was associated with a decreased risk of BE. Increasing waist circumference was associated with an increased risk of BE in the mutually adjusted population-based and GERD control models.

CONCLUSIONS

Although abdominal obesity is associated with an increased risk of BE, there is an inverse association between gluteofemoral obesity and BE, particularly among men.

Is there an effect of ghrelin/ghrelin analogs on cancer? A systematic review

Ghrelin is a hormone with multiple physiologic functions, including promotion of growth hormone release, stimulation of appetite and regulation of energy homeostasis. Treatment with ghrelin/ghrelin-receptor agonists is a prospective therapy for disease-related cachexia and malnutrition. In vitro studies have shown high expression of ghrelin in cancer tissue, although its role including its impact in cancer risk and progression has not been established. We performed a systematic literature review to identify peer-reviewed human or animal in vivo original research studies of ghrelin, ghrelin-receptor agonists, or ghrelin genetic variants and the risk, presence, or growth of cancer using structured searches in PubMed database as well as secondary searches of article reference lists, additional reviews and meta-analyses. Overall, 45 (73.8%) of the 61 studies reviewed, including all 11 involving exogenous ghrelin/ghrelin-receptor agonist treatment, reported either a null (no statistically significant difference) or inverse association of ghrelin/ghrelin-receptor agonists or ghrelin genetic variants with cancer risk, presence or growth; 10 (16.7%) studies reported positive associations; and 6 (10.0%) reported both negative or null and positive associations. Differences in serum ghrelin levels in cancer cases vs controls (typically lower) were reported for some but not all cancers. The majority of in vivo studies showed a null or inverse association of ghrelin with risk and progression of most cancers, suggesting that ghrelin/ghrelin-receptor agonist treatment may have a favorable safety profile to use for cancer cachexia. Additional large-scale prospective clinical trials as well as basic bioscientific research are warranted to further evaluate the safety and benefits of ghrelin treatment in patients with cancer.

Ghrelin and Leptin Have a Complex Relationship with Risk of Barrett's Esophagus

BACKGROUND

Abdominal obesity is a risk factor for Barrett's esophagus independent of GERD symptoms, but little is understood about the biological mechanisms between obesity and the carcinogenic pathway of esophageal adenocarcinoma.

AIMS

To evaluate whether ghrelin and leptin may partially explain the association between obesity and Barrett's esophagus.

METHODS

We conducted a case-control study using patients with a new diagnosis of Barrett's esophagus (cases) and two control groups frequency matched to cases for age, gender, and geographic region: (1) patients with gastroesophageal reflux disease (GERD) and (2) a sample of the general population. We generated odds ratios using logistic regressions to evaluate quartiles of serum ghrelin or serum leptin, adjusting for known risk factors for Barrett's esophagus. We evaluated potential interaction variables using cross products and ran stratified analyses to generate stratum-specific odds ratios.

RESULTS

A total of 886 participants were included in the analysis. Higher ghrelin concentrations were associated with an increased risk of Barrett's esophagus, when compared to the population controls, but not the GERD controls. Ghrelin concentrations were not associated with the frequency of GERD symptoms, but ghrelin's relationship with Barrett's esophagus varied significantly with the frequency of GERD symptoms. Leptin concentrations were positively associated with at least weekly GERD symptoms among the population controls and were inversely associated with Barrett's esophagus only among the GERD controls. Adjusting for waist circumference did not change the main associations.

CONCLUSION

Higher levels of ghrelin were associated with an increased risk of Barrett's esophagus among the general population. In contrast, leptin was positively associated with frequent GERD symptoms, but inversely associated with the risk of Barrett's esophagus among the GERD controls.

Ghrelin and gastroparesis as early predictors of clinical outcomes in acute pancreatitis

BACKGROUND

Impaired motor and hormonal gastrointestinal functions have been implicated in the pathogenesis of acute pancreatitis. The aim of the present study was to investigate the predictive value of the Gastroparesis Cardinal Symptom Index and serum ghrelin in the development of clinically meaningful outcomes in patients with acute pancreatitis.

METHODS

This was a prospective clinical study. The Gastroparesis Cardinal Symptom Index and serum ghrelin were measured for 48 h after hospitalization. Univariate and multivariate logistic regression analyses were conducted.

RESULTS

The Gastroparesis Cardinal Symptom Index total score alone on day 2 was a significant predictor of oral feeding intolerance in both unadjusted (odds ratio 1.21 (1.01-1.46), P = 0.04) and adjusted (odds ratio 1.30 (1.01-1.69), P = 0.05) analyses. Adding ghrelin to Gastroparesis Cardinal Symptom Index further improved prediction in both unadjusted (odds ratio 1.26 (1.02-1.56), P = 0.03) and adjusted (odds ratio 1.53 (1.00-2.35), P = 0.05) analyses.

CONCLUSION

This pilot study demonstrates that the Gastroparesis Cardinal Symptom Index has a potential to be used as a predictor of oral feeding intolerance. Ghrelin, when combined with the Gastroparesis Cardinal Symptom Index, may further improve the predictive accuracy. These findings need to be confirmed in larger studies.

The Influence of Ghrelin on the Development of Dextran Sodium Sulfate-Induced Colitis in Rats

Ghrelin has protective and therapeutic effects in the gut. The aim of present studies was to investigate the effect of treatment with ghrelin on the development of colitis evoked by dextran sodium sulfate (DSS). Methods. Studies have been performed on rats. Colitis was induced by adding 5% DSS to the drinking water for 5 days. During this period animals were treated intraperitoneally twice a day with saline or ghrelin given at the dose of 8 nmol/kg/dose. On the sixth day, animals were anesthetized and the severity of colitis was assessed. Results. Treatment with ghrelin during administration of DSS reduced the development of colitis. Morphological features of colonic mucosa exhibited a reduction in the area and deep of mucosal damage. Ghrelin reversed the colitis-induced decrease in blood flow, DNA synthesis, and superoxide dismutase activity in colonic mucosa. These effects were accompanied by a decrease in the colitis-evoked increase in mucosal concentration of interleukin-1β and malondialdehyde. Treatment with ghrelin reversed the DSS-induced reduction in body weight gain. Conclusions. Administration of ghrelin exhibits the preventive effect against the development of DSS-induced colitis. This effect seems to be related to ghrelin's anti-inflammatory and antioxidative properties.

Associations of Circulating Gut Hormone and Adipocytokine Levels with the Spectrum of Gastroesophageal Reflux Disease

OBJECTIVE

The pathogenesis of gastroesophageal reflux disease (GERD) is complex and poorly understood. We aim to investigate the association of various circulating peptide hormones with heterogenous manifestations of GERD.

METHODS

One hundred and four patients that had experienced typical GERD symptoms (heartburn and/or acid regurgitation) for at least 3 episodes per week in the past 3 months were enrolled. All patients received a baseline assessment of symptom severity and frequency with the Reflux Disease Questionnaire and an upper endoscopy to classify GERD into erosive esophagitis (EE, n = 67), non-erosive esophagitis (NE, n = 37), and Barrett's esophagus (BE, n = 8). Fifty asymptomatic subjects with an endoscopically normal esophagus were recruited as the control group. Complete anthropometric measures and blood biochemistry were obtained and fasting serum levels of adipocytokines (adiponectin and leptin) and gut hormones (ghrelin and peptide YY (PYY)) were determined by enzyme-linked immunosorbent assay in all subjects.

RESULTS

All circulating peptide hormone levels were not statistically different between the GERD and control groups. However, GERD patients appeared to have lower PYY levels [median (25th-75th percentile), 80.1 (49.8-108.3) vs. 99.4 (65.8-131.9) pg/ml, p = 0.057] compared with control subjects. Among the GERD patients, ghrelin levels were inversely associated with the frequency and severity of acid regurgitation. In male GERD patients, EE was associated with significantly higher PYY levels [107.0 (55.0-120.8) vs. 32.8 (28.7-84.5) pg/ml, p = 0.026] but lower adiponectin levels [6.7 (5.6-9.3) vs. 9.9 (9.6-10.6) μg/ml, p = 0.034] than NE. Patients with BE had significantly lower adiponectin levels [6.0 (5.1-9.2) vs. 9.2 (7.1-11.2) μg/ml, p = 0.026] than those without BE.

CONCLUSIONS

Humoral derangement of circulating peptide hormones might participate in inflammation and symptom perception in patients suffering from GERD. Further studies to clarify the exact role of these hormones in the pathogenesis of GERD are warranted.

A review of the epidemiology of Barrett's oesophagus and oesophageal adenocarcinoma

While the incidence rates of many cancers have decreased in past decades, the incidence of oesophageal adenocarcinoma continues to increase. The only known precursor for oesophageal adenocarcinoma is Barrett's oesophagus. Studies conducted have identified white race, male sex, GORD, cigarette smoking, obesity, and the absence of Helicobacter pylori status as risk factors for oesophageal adenocarcinoma. Other potential associations include dietary factors and the absence of non-steroidal anti-inflammatory drug use. Many individual studies have been limited by sample size and several meta-analyses have pooled data from studies to address this limitation. In this review we present a synthesis of these studies and summarize current knowledge of risk factors for both oesophageal adenocarcinoma and Barrett's oesophagus.

Pathophysiological mechanisms linking obesity and esophageal adenocarcinoma

In recent decades there has been a dramatic rise in the incidence of esophageal adenocarcinoma (EAC) in the developed world. Over approximately the same period there has also been an increase in the prevalence of obesity. Obesity, especially visceral obesity, is an important independent risk factor for the development of gastro-esophageal reflux disease, Barrett’s esophagus and EAC. Although the simplest explanation is that this mediated by the mechanical effects of abdominal obesity promoting gastro-esophageal reflux, the epidemiological data suggest that the EAC-promoting effects are independent of reflux. Several, not mutually exclusive, mechanisms have been implicated, which may have different effects at various points along the reflux-Barrett’s-cancer pathway. These mechanisms include a reduction in the prevalence of Helicobacter pylori infection enhancing gastric acidity and possibly appetite by increasing gastric ghrelin secretion, induction of both low-grade systemic inflammation by factors secreted by adipose tissue and the metabolic syndrome with insulin-resistance. Obesity is associated with enhanced secretion of leptin and decreased secretion of adiponectin from adipose tissue and both increased leptin and decreased adiponectin have been shown to be independent risk factors for progression to EAC. Leptin and adiponectin have a set of mutually antagonistic actions on Barrett’s cells which appear to influence the progression of malignant behaviour. At present no drugs are of proven benefit to prevent obesity associated EAC. Roux-en-Y reconstruction is the preferred bariatric surgical option for weight loss in patients with reflux. Statins and aspirin may have chemopreventative effects and are indicated for their circulatory benefits.

Association between Helicobacter pylori and Barrett's esophagus, erosive esophagitis, and gastroesophageal reflux symptoms

BACKGROUND & AIMS

Infection with Helicobacter pylori, particularly the cytotoxin-associated gene A (cagA)+ strain, is believed to protect against Barrett's esophagus, but it is not clear if it protects against gastroesophageal reflux disease (GERD). We aimed to determine whether H pylori infection is associated with GERD symptoms, erosive esophagitis, and Barrett's esophagus within the same cohort.

METHODS

We analyzed data from a case-control study of 533 men (ages, 50-79 y) who underwent colorectal cancer screening at 2 tertiary medical centers in Michigan between 2008 and 2011 and who also were recruited to undergo upper endoscopy. We assessed 80 additional men found to have Barrett's esophagus during clinically indicated upper-endoscopy examinations. Logistic regression was used to estimate the associations between serum antibodies against H pylori or cagA and GERD symptoms, esophagitis, and Barrett's esophagus, compared with randomly selected men undergoing colorectal cancer screens (n = 177).

RESULTS

H pylori infection was associated inversely with Barrett's esophagus (odds ratio [OR], 0.53; 95% confidence interval [CI], 0.29-0.97), particularly the cagA+ strain (OR, 0.36; 95% CI, 0.14-0.90). There was a trend toward an inverse association with erosive esophagitis (H pylori OR, 0.63; 95% CI, 0.37-1.08; and cagA+ OR, 0.47; 95% CI, 0.21-1.03). However, GERD symptoms were not associated with H pylori infection (OR, 0.948; 95% CI, 0.548-1.64; and cagA+ OR, 0.967; 95% CI, 0.461-2.03).

CONCLUSIONS

Based on a case-control study, infection with H pylori, particularly the cagA+ strain, is associated inversely with Barrett's esophagus. We observed a trend toward an inverse association with esophagitis, but not with GERD symptoms.

Impairment of ghrelin synthesis in Helicobacter pylori-colonized stomach: New clues for the pathogenesis of H. pylori-related gastric inflammation

Ghrelin, the ligand of growth hormone secretagogue receptor 1a, takes part in several functions of the digestive system, including regulation of appetite, energy homeostasis, gastric acid secretion and motility. Ghrelin has also immunoregulatory properties and is supposed to inhibit some inflammatory pathways that can mediate gastric damage. Interestingly, ghrelin synthesis is reduced in the gastric mucosa of patients with Helicobacter pylori (H. pylori) infection, a worldwide condition inducing a T helper (Th)1/Th17 cell response-driven gastritis, which may evolve towards gastric atrophy and cancer. In this article, we review the available data on the expression of ghrelin in H. pylori infection and discuss how the defective ghrelin synthesis may contribute to sustain the ongoing inflammatory response in this disease.

Associations of diabetes mellitus, insulin, leptin, and ghrelin with gastroesophageal reflux and Barrett's esophagus

BACKGROUND & AIMS

Insulin and leptin have proliferative and anti-apoptotic effects. Ghrelin promotes gastric emptying and secretion of growth hormone and inhibits inflammation. We assessed whether diabetes mellitus and serum levels of insulin, leptin, and ghrelin are associated with gastroesophageal reflux disease (GERD) and Barrett's esophagus.

METHODS

We conducted a case-control study in 822 men undergoing colorectal cancer screening who were recruited to also undergo upper endoscopy. We identified 70 with Barrett's esophagus; 80 additional men with Barrett's esophagus were recruited shortly after their clinical diagnoses. Serum levels of insulin, leptin, and ghrelin were assayed in all 104 fasting men with Barrett's esophagus without diabetes and 271 without diabetes or Barrett's esophagus. Logistic regression was used to estimate the effects of diabetes and levels of insulin, leptin, and ghrelin on GERD and Barrett's esophagus.

RESULTS

Among men with GERD, diabetes was inversely associated with Barrett's esophagus (adjusted odds ratio [OR] = 0.383; 95% confidence interval [CI]: 0.179-0.821). Among nondiabetics, hyperinsulinemia was positively associated with Barrett's esophagus, but the association was attenuated by adjustment for leptin and ghrelin. Leptin was positively associated with Barrett's esophagus, adjusting for obesity, GERD, and levels of insulin and ghrelin (OR for 3(rd) vs 1(st) tertile = 3.25; 95% CI: 1.29-8.17); this association was stronger in men with GERD (P = .01 for OR heterogeneity). Ghrelin was positively associated with Barrett's esophagus (OR for an increment of 400 pg/mL = 1.39; 95% CI: 1.09-1.76), but inversely associated with GERD (OR for 3(rd) vs 1(st) tertile = 0.364; 95% CI: 0.195-0.680).

CONCLUSIONS

Based on a case-control study, leptin was associated with Barrett's esophagus, particularly in men with GERD. Serum insulin level was associated with Barrett's esophagus, but might be mediated by leptin. Serum ghrelin was inversely associated with GERD, as hypothesized, but positively associated with Barrett's esophagus, contrary to our hypothesis. Additional studies are needed in men and women to replicate these findings.

Serum ghrelin; a new surrogate marker of gastric mucosal alterations in upper gastrointestinal carcinogenesis

Background

A few studies have indicated inverse relationships between serum ghrelin and gastric and esophageal cancers but those associations have been restricted to specific populations, including smokers and overweight individuals. We examined the association between ghrelin and gastroesophageal cancers and atrophic gastritis in a population-based setting.

Methods

In total 220 gastroesophageal cancers, comprising non-cardia and cardia gastric cancer, esophageal adenocarcinoma, esophageal squamous cell carcinoma (SCC) and age and gender-matched controls were recruited. Serum ghrelin, pepsinogen I/II ratio (PGI/II) and anti-H.pylori IgG antibodies were measured. Relationships between ghrelin and gastroesophageal cancers, after adjustment for PGI/II ratio, H.pylori status and smoking, were tested using logistic regression. Furthermore, in 125 endoscopically normal volunteers, with and without histological atrophic gastritis, the relationship with ghrelin was compared.

Results

Serum ghrelin (lowest vs. highest quintile) was inversely associated with gastric cancer: OR (95% CI) 8.71 (1.70–44.59) for cardia and 6.58 (1.26–34.46) for non-cardia cancer. Lower serum ghrelin was also associated with esophageal SCC: OR (95% CI) 5.69 (1.36–23.78), but not with esophageal adenocarcinoma. A similar association was observed between gastric cancer (cardia and non-cardia) and esophageal SCC when serum ghrelin was analysed as a continuous scaled variable. In endoscopically-normal volunteers, extensive atrophic gastritis was associated with low serum ghrelin [OR (95% CI) 0.25 (0.10–0.64)].

Conclusion

Inverse associations between ghrelin and some gastroesophageal cancers suggest a potential role for serum ghrelin as a biomarker of upper gastrointestinal cancers and atrophic gastritis. In areas with a high incidence of gastric and/or esophageal cancer, screening might be more effectively targeted to individuals with low serum ghrelin in addition to the PGI/II ratio.

The ghrelin axis--does it have an appetite for cancer progression?

Ghrelin, the endogenous ligand for the GH secretagogue receptor (GHSR), is a peptide hormone with diverse physiological roles. Ghrelin regulates GH release, appetite and feeding, gut motility, and energy balance and also has roles in the cardiovascular, immune, and reproductive systems. Ghrelin and the GHSR are expressed in a wide range of normal and tumor tissues, and a fluorescein-labeled, truncated form of ghrelin is showing promise as a biomarker for prostate cancer. Plasma ghrelin levels are generally inversely related to body mass index and are unlikely to be useful as a biomarker for cancer, but may be useful as a marker for cancer cachexia. Some single nucleotide polymorphisms in the ghrelin and GHSR genes have shown associations with cancer risk; however, larger studies are required. Ghrelin regulates processes associated with cancer, including cell proliferation, apoptosis, cell migration, cell invasion, inflammation, and angiogenesis; however, the role of ghrelin in cancer is currently unclear. Ghrelin has predominantly antiinflammatory effects and may play a role in protecting against cancer-related inflammation. Ghrelin and its analogs show promise as treatments for cancer-related cachexia. Further studies using in vivo models are required to determine whether ghrelin has a role in cancer progression.

Ghrelin expression in esophageal adenocarcinoma and Barrett's esophagus

AIM: To investigate the expression of Ghrelin in the esophageal mucosa of patients with esophageal adenocarcinoma and those with Barrett's esophagus (BE).

METHODS: Thirty patients with esophageal adenocarcinoma, 35 patients with BE, and 35 normal controls were enrolled in the study. The expression of Ghrelin in specimens taken from the above subjects was detected by immunohistochemistry.

RESULTS: The expression of Ghrelin in esophageal adenocarcinoma was lower than that in normal controls and patients with BE. The expression of Ghrelin in the BE group was higher than that in the control group (1.34 ± 0.51 vs 4.86 ± 0.82 vs 3.54 ± 0.79, F = 27.21, P < 0.05). In the esophageal adenocarcinoma group, the expression of Ghrelin in moderately and well differentiated specimens were higher than that in poorly differentiated specimens (Z = 4.60, P < 0.05).

CONCLUSION: The expression of Ghrelin in the esophageal adenocarcinoma is different from that in BE. The level of Ghrelin changes during the evolution of esophageal cancer. Disruption of the esophageal Ghrelin-producing mechanism may occur during esophageal carcinogenesis. There is an association between the degree of esophageal carcinoma differentiation and Ghrelin production.

Barrett's esophagus: clinical features, obesity, and imaging

The following includes commentaries on clinical features and imaging of Barrett's esophagus (BE); the clinical factors that influence the development of BE; the influence of body fat distribution and central obesity; the role of adipocytokines and proinflammatory markers in carcinogenesis; the role of body mass index (BMI) in healing of Barrett's epithelium; the role of surgery in prevention of carcinogenesis in BE; the importance of double-contrast esophagography and cross-sectional images of the esophagus; and the value of positron emission tomography/computed tomography.

Risk factors for neoplastic progression in Barrett’s esophagus

Barrett’s esophagus (BE) confers a significant increased risk for development of esophageal adenocarcinoma (EAC), with the pathogenesis appearing to progress through a “metaplasia-dysplasia-carcinoma” (MDC) sequence. Many of the genetic insults driving this MDC sequence have recently been characterized, providing targets for candidate biomarkers with potential clinical utility to stratify risk in individual patients. Many clinical risk factors have been investigated, and associations with a variety of genetic, specific gastrointestinal and other modifiable factors have been proposed in the literature. This review summarizes the current understanding of the mechanisms involved in neoplastic progression of BE to EAC and critically appraises the relative roles and contributions of these putative risk factors from the published evidence currently available.

Helicobacter pylori infection and the risks of Barrett's oesophagus: a population-based case-control study

Infection with Helicobacter pylori is associated with significantly reduced risks of oesophageal adenocarcinoma; however, few studies have examined the association between H. pylori and Barrett's oesophagus (BO), the precursor lesion. We explored the relationship between H. pylori infection and BO and sought to identify potential modifiers. We compared the prevalence of positive H. pylori serology among 217 adults with simple BO (without dysplasia), 95 with dysplastic BO and 398 population controls sourced from the metropolitan Brisbane area. We determined H. pylori serostatus using enzyme-linked immunosorbent assay. To estimate relative risks, we calculated odds ratios (OR) and 95% confidence intervals (CI) using multivariable logistic regression in the entire sample and stratified by factors known to cause BO. The prevalence of H. pylori seropositivity was 12%, 3%, and 18%, respectively, among patients with simple BO, dysplastic BO and population controls. BO patients were significantly less likely to have antibodies for H. pylori (Simple BO: OR = 0.51, 95% CI: 0.30-0.86; Dysplastic BO: OR = 0.10, 95% CI: 0.03-0.33) than population controls. For simple BO, the association was diminished after adjustment for frequency of gastro-oesophageal reflux (GOR) symptoms. Adjustment for frequency of GOR symptoms did not substantially alter the observed effect for dysplastic BO. Although there was some variation in the magnitude of risk estimates across strata of age, sex, GOR symptoms and use of proton pump inhibitors or H2-receptor antagonists, the differences were uniformly nonsignificant. Helicobacter pylori infection is inversely associated with BO, and our findings suggest that decreased acid load is not the only mechanism underlying the H. pylori protective effect.

Does Helicobacter pylori infection protect against esophageal diseases in Asia?

The speculations on the protective role of Helicobacter pylori against gastroesophageal reflux disease (GERD) originated from epidemiological observations. These studies have shown that the rising trend of GERD is coincident with declining prevalence of H. pylori and peptic ulcer disease in Asia. Furthermore, most case-control and population-based studies suggest a negative association between H. pylori infection and GERD. It is generally believed that the preponderance of cagA+ and vacA+ virulent strains and proinflammatory interleukin-1 beta polymorphism increase the risk of hypochlohydria and protects against the development of GERD in Asian population. Recovery of gastric acid secretion and emergence of reflux esophagitis has been reported after H. pylori eradication in patients with corpus gastritis and atrophic gastritis. Recent studies have also reported that H. pylori eradication leads to recovery of ghrelin secreting cells in the gastric corpus and a rise in plasma ghrelin levels, which may contribute to obesity through its appetite-stimulating action and predispose to GERD. The prevalence of H. pylori infection is generally lower in younger Asians who enjoy improved socioeconomic status and sanitation compared with their older counterparts. The Asian population is probably facing a rising generation with high gastric acid and ghrelin secretion rates. These physiological changes may contribute to increased dietary calorie intake, obesity and increased prevalence of GERD.

The relationship between serum ghrelin and the risk of gastric and esophagogastric junctional adenocarcinomas

BACKGROUND

Cancers of the upper gastrointestinal tract remain a substantial cause of morbidity and mortality worldwide. Ghrelin is a hormone produced in the oxyntic glands of the stomach, and under conditions of chronic inflammation and atrophy, serum ghrelin concentrations decrease. However, the relationship between ghrelin and the risk of gastric and esophagogastric junctional cancers has not been investigated.

METHODS

We conducted a nested case-control study within the Finnish Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study to examine the relationship between serum ghrelin concentration and the risk of gastric noncardia adenocarcinoma (GNCA) and esophagogastric junctional adenocarcinoma (EGJA). Data from 261 GNCA patients, 98 EGJA patients, and 441 control subjects were analyzed. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated using logistic regression with adjustment for potential confounders. Lag analysis was also performed to investigate the temporal nature of the associations between baseline serum pepsinogen I and ghrelin in GNCA and EGJA patients. All statistical tests were two-sided.

RESULTS

Lower concentrations of serum ghrelin were statistically significantly associated with an increased risk of both GNCA (adjusted OR = 1.75, 95% CI = 1.49 to 2.04; P < .001) and EGJA (adjusted OR = 1.56, 95% CI = 1.28 to 1.89, P < .001). A multivariable model found that the risk of both GNCA and EGJA were statistically significantly increased for those individuals in the lowest quartile of serum ghrelin levels compared with those in the highest quartile (OR of GNCA = 5.63, 95% CI = 3.16 to 10.03; OR of EGJA = 4.90, 95% CI = 2.11 to 11.35). The statistical significance of these associations remained even after restricting the analysis to those patients who developed cancer more than 10 years after baseline serum ghrelin measurements.

CONCLUSION

Low baseline concentrations of serum ghrelin were associated with a statistically significant increase in the risk of GNCA and EGJA, suggesting a potential role for gastric hormones in carcinogenesis.

Obesity, metabolic syndrome and esophageal adenocarcinoma: epidemiology, etiology and new targets

BACKGROUND

Rates of distal and junctional adenocarcinomas are increasing in Western countries.

METHODS

Systematic review of epidemiological evidence linking obesity to esophageal adenocarcinoma (EA) was performed for studies published from 2005 to 2010. The current understanding of obesity's role in the etiology and potential dysplastic progression of Barrett's esophagus (BE) to EA is reviewed.

RESULTS

Accumulating epidemiological studies provide evidence of obesity's role as a driving force behind the increasing rates of EA. The simplest construct is that obesity promotes reflux, causing chronic inflammation and BE, predisposing to adenocarcinoma. However, as obesity is positively associated with the prevalence of many cancers, other mechanisms are important. A link may exist between fat distribution patterns and the risk of BE and EA. Altered metabolic profiles in the metabolic syndrome (MetS) may be a key factor in cell cycle/genetic abnormalities that mark the progression of BE towards cancer. Research highlighting a unique role of MetS in the length of BE, and its association with systemic inflammation and insulin resistance is discussed, as well as adipokine receptor expression in both BE and esophageal epithelium, and how MetS and the systemic response impacts on key regulators of inflammation and tumorigenesis. CONCLUSIONS/IMPACT: Obesity is positively associated with EA. The systemic inflammatory state consequent on the altered metabolism of obese patients, and the associated impact of adipocytokines and pro-coagulant factors released by adipocytes in central fat, may underlie obesity's relationship to this cancer. Novel therapeutic agents that may antagonize adipo-cytokines and potentially offer a promising role in cancer therapy are discussed.

Helicobacter pylori infection and circulating ghrelin levels - a systematic review

BACKGROUND

The nature of the association between ghrelin, an orexigenic hormone produced mainly in the stomach, and Helicobacter pylori (H pylori), a bacterium that colonises the stomach, is still controversial. We examined available evidence to determine whether an association exists between the two; and if one exists, in what direction.

METHODS

We reviewed original English language studies on humans reporting circulating ghrelin levels in H pylori infected and un-infected participants; and circulating ghrelin levels before and after H pylori eradication. Meta-analyses were conducted for eligible studies by combining study specific estimates using the inverse variance method with weighted average for continuous outcomes in a random effects model.

RESULTS

Seventeen out of 27 papers that reported ghrelin levels in H pylori positive and negative subjects found lower circulating ghrelin levels in H pylori positive subjects; while 10 found no difference. A meta-analysis of 19 studies with a total of 1801 participants showed a significantly higher circulating ghrelin concentration in H pylori negative participants than in H pylori positive participants (Effect estimate (95%CI) = -0.48 (-0.60, -0.36)). However, eradicating H pylori did not have any significant effect on circulating ghrelin levels (Effect estimate (95% CI) = 0.08 (-0.33, 0.16); Test for overall effect: Z = 0.67 (P = 0.5)).

CONCLUSIONS

We conclude that circulating ghrelin levels are lower in H pylori infected people compared to those not infected; but the relationship between circulating ghrelin and eradication of H pylori is more complex.

Helicobacter pylori infection and circulating ghrelin levels - a systematic review

Background

The nature of the association between ghrelin, an orexigenic hormone produced mainly in the stomach, and Helicobacter pylori (H pylori), a bacterium that colonises the stomach, is still controversial. We examined available evidence to determine whether an association exists between the two; and if one exists, in what direction.

Methods

We reviewed original English language studies on humans reporting circulating ghrelin levels in H pylori infected and un-infected participants; and circulating ghrelin levels before and after H pylori eradication. Meta-analyses were conducted for eligible studies by combining study specific estimates using the inverse variance method with weighted average for continuous outcomes in a random effects model.

Results

Seventeen out of 27 papers that reported ghrelin levels in H pylori positive and negative subjects found lower circulating ghrelin levels in H pylori positive subjects; while 10 found no difference. A meta-analysis of 19 studies with a total of 1801 participants showed a significantly higher circulating ghrelin concentration in H pylori negative participants than in H pylori positive participants (Effect estimate (95%CI) = -0.48 (-0.60, -0.36)). However, eradicating H pylori did not have any significant effect on circulating ghrelin levels (Effect estimate (95% CI) = 0.08 (-0.33, 0.16); Test for overall effect: Z = 0.67 (P = 0.5)).

Conclusions

We conclude that circulating ghrelin levels are lower in H pylori infected people compared to those not infected; but the relationship between circulating ghrelin and eradication of H pylori is more complex.

Current and potential roles of ghrelin in clinical practice

Ghrelin is a novel GH-releasing peptide, which has been identified as an endogenous ligand for GH-secretagogue receptor. Ghrelin is mainly secreted by the stomach and plays a critical role in a variety of physiological processes including endocrine, metabolic, cardiovascular, immunological, and other actions. Ghrelin stimulates food intake via hypothalamic neurons and causes a positive energy balance and body weight gain by decreasing fat utilization and promoting adiposity. Given the multiple effects of ghrelin, its potential clinical applications have been evaluated in various conditions. Preliminary trials have shown that it may prove valuable in the management of disease-induced cachexia. Ghrelin may improve the wasting syndrome through GH-dependent or GH-independent effects. Moreover, ghrelin may play a role in the management of disorders of gut motility and obesity. Finally, other potential clinical applications of ghrelin include the treatment of patients with diabetes mellitus, infections, rheumatological diseases or GH deficiency and the diagnosis of this hormonal disorder.

Ghrelin gene products and the regulation of food intake and gut motility

A breakthrough using "reverse pharmacology" identified and characterized acyl ghrelin from the stomach as the endogenous cognate ligand for the growth hormone (GH) secretagogue receptor (GHS-R) 1a. The unique post-translational modification of O-n-octanoylation at serine 3 is the first in peptide discovery history and is essential for GH-releasing ability. Des-acyl ghrelin, lacking O-n-octanoylation at serine 3, is also produced in the stomach and remains the major molecular form secreted into the circulation. The third ghrelin gene product, obestatin, a novel 23-amino acid peptide identified from rat stomach, was found by comparative genomic analysis. Three ghrelin gene products actively participate in modulating appetite, adipogenesis, gut motility, glucose metabolism, cell proliferation, immune, sleep, memory, anxiety, cognition, and stress. Knockdown or knockout of acyl ghrelin and/or GHS-R1a, and overexpression of des-acyl ghrelin show benefits in the therapy of obesity and metabolic syndrome. By contrast, agonism of acyl ghrelin and/or GHS-R1a could combat human anorexia-cachexia, including anorexia nervosa, chronic heart failure, chronic obstructive pulmonary disease, liver cirrhosis, chronic kidney disease, burn, and postsurgery recovery, as well as restore gut dysmotility, such as diabetic or neurogenic gastroparesis, and postoperative ileus. The ghrelin acyl-modifying enzyme, ghrelin O-Acyltransferase (GOAT), which attaches octanoate to serine-3 of ghrelin, has been identified and characterized also from the stomach. To date, ghrelin is the only protein to be octanylated, and inhibition of GOAT may have effects only on the stomach and is unlikely to affect the synthesis of other proteins. GOAT may provide a critical molecular target in developing novel therapeutics for obesity and type 2 diabetes.

Ghrelin and its therapeutic potential for cachectic patients

The discovery of ghrelin has resulted in the development of approaches to appetite, enabling a better understanding of the mechanisms regulating appetite through molecular analyses. Ghrelin is a 28-amino acid peptide that was isolated from the stomach only a decade ago, and has recently been investigated as a potential therapeutic endogenous agent. This peptide increases appetite, adjusts energy balance, suppresses inflammation, and enhances the release of growth hormone from the pituitary gland. Although many bioactive substances such as peptide YY, leptin, adiponectin and obestatin are involved in appetite control, ghrelin is the only known peptide to signal starvation information from a peripheral organ to the central nervous system, contributing to an increase in appetite. Clinical trials have revealed the effectiveness of ghrelin in increasing lean body mass and activity in cachectic patients. As shown in clinical research on humans and basic research using animal models, cachexia often occurs in response to excess release of proinflammatory cytokines and induces further appetite loss, which aggravates the physiological status of underlying diseases. Ghrelin functions as a protector against the vicious cycle of the cachectic paradigm through orexigenic, anabolic and anti-inflammatory effects, so administration of ghrelin may be able to improve quality of life in cachectic patients. We show here a significant role of ghrelin in the pathophysiology of cachectic diseases and the possibility of clinical applications.

Helicobacter pylori and esophageal cancer risk: a meta-analysis

We conducted this meta-analysis to examine the association between Helicobacter pylori and esophageal adenocarcinoma (EAC) and esophageal squamous cell carcinoma. We searched the PubMed database, the ISI database, and the references of the selected articles. Case-control or nested case-control studies were selected if they used serology or endoscopic methods to detect H. pylori in the stomach and if control subjects were not restricted to upper gastrointestinal tract cancer or peptic ulcer disease patients. A total of 19 studies were used for this analysis. Summary odds ratios (OR) and 95% confidence intervals (95% CI) were calculated using the DerSimonian-Laird method. Q statistics and I(2) statistics were calculated to examine heterogeneity. Subgroup analyses were conducted by CagA status. For EAC, the summary OR (95% CI) was 0.56 (0.46-0.68). There was little heterogeneity among studies (I(2) = 15%). Further analysis showed that colonization with CagA-positive strains was inversely associated with EAC risk (OR, 0.41; 95% CI, 0.28-0.62) but colonization with CagA-negative strains was not (OR, 1.08; 95% CI, 0.76-1.53). For esophageal squamous cell carcinoma, the summary OR (95% CI) was 1.10 (0.78-1.55). However, there was substantial heterogeneity among studies (I(2) = 73%), with statistically significant associations in both directions. Our results suggest an inverse association between CagA-positive H. pylori colonization and risk of EAC. The prominent decline of H. pylori colonization in the past few decades may be partly responsible for the recent increase in EAC incidence in Western countries.

Gastroesophageal reflux disease: an Asian perspective

The prevalence of gastroesophageal reflux disease (GERD) ranges from 2.5% to 7.1% in most population-based studies in Asia. There is evidence that GERD and its complications are rising, coinciding with a decline in Helicobacter pylori (H. pylori) infection. Asian GERD patients share similar risk factors and pathophysiological mechanisms with their Western counterparts. Possible causes for the lower prevalence of GERD include less obesity and hiatus hernia, a lesser degree of esophageal dysmotility, a high prevalence of virulent strains of H. pylori, and low awareness. Owing to the lack of precise translation for 'heartburn' in most Asian languages, reflux symptoms are often overlooked or misinterpreted as dyspepsia or chest pain. Furthermore, a symptom-based diagnosis with a therapeutic trial of the proton pump inhibitor (PPI) may be hampered by the high prevalence of H. pylori-related disease. The risk stratification for prompt endoscopy, use of a locally-validated, diagnostic symptom questionnaire, and response to H. pylori'test and treat' help improve the accuracy of the PPI test for diagnoses. PPI remain the gold standard treatment, and 'on-demand' PPI have been shown to be a cost-effective, long-term treatment. The clinical course of GERD is benign in most patients in Asia. The risk of progression from non-erosive reflux disease to erosive esophagitis is low, and treatment response to a conventional dose of PPI is generally higher. Although H. pylori eradication may lead to more resilient GERD in a subset of patients, the benefits of H. pylori eradication outweigh the risks, especially in Asian populations with a high incidence of gastric cancer.

A pilot study of the association of low plasma adiponectin and Barrett's esophagus

BACKGROUND AND AIMS

Gastroesophageal reflux disease (GERD) and obesity are associated with esophageal adenocarcinoma (EAC). We hypothesized that the obesity-EAC relation is mediated by factors secreted from adipocytes. Adiponectin is a peptide secreted by adipocytes, and its plasma levels are inversely associated with obesity. We aimed to estimate the effect of circulating adiponectin on the risk of Barrett's esophagus (BE), an accepted precursor of EAC, controlling for GERD symptoms and other potential confounders.

METHODS

We conducted a case-control study in cases of BE compared with controls without BE; most controls had GERD. Odds ratios (OR), corresponding to associations with BE, were estimated from conditional and unconditional logistic regression analyses of 50 matched pairs.

RESULTS

BE was inversely associated with plasma adiponectin level (OR for each 10-microg/mL decrement 4.7, 95% confidence interval [CI] 1.4-15.0) and positively associated with GERD duration >or=10 yr, male gender, tobacco smoking, body mass index (BMI), waist circumference, and waist-to-hip ratio. Further adjustment for GERD duration, tobacco use, and BMI increased the adiponectin-BE association (OR 6.4, 95% CI 1.1-37.0), but the estimated OR was reduced when adjusting for measures of abdominal obesity (e.g., OR 2.5, 95% CI 0.49-13.00) and further adjusting for gender (OR 1.8, 95% CI 0.66-4.70).

CONCLUSIONS

Despite methodologic limitations, including the small sample size, our findings suggest that adiponectin may be involved in the etiology of BE. Rather than simply a mechanical effect of obesity promoting GERD, the effects of abdominal obesity on the risk of BE might be mediated by adiponectin and other circulating factors.