Ghrelin receptor regulates adipose tissue inflammation in aging

Loss-of-Function GHSR Variants Are Associated With Short Stature and Low IGF-I

CONTEXT

The growth hormone (GH) secretagogue receptor, encoded by GHSR, is expressed on somatotrophs of the pituitary gland. Stimulation with its ligand ghrelin, as well as its constitutive activity, enhances GH secretion. Studies in knockout mice suggest that heterozygous loss-of-function of GHSR is associated with decreased GH response to fasting, but patient observations in small case reports have been equivocal.

OBJECTIVE

This work aims to establish the phenotype of GHSR haploinsufficiency and its growth response to GH treatment.

METHODS

This case series includes 26 patients with short stature and heterozygous GHSR variants. Pathogenicity was studied in vitro using total protein levels, cell surface expression, and receptor activity in basal, stimulated, and inhibited states.

RESULTS

Ten different variants were identified, of which 6 were novel. Variants showed either partial or complete loss of function, primarily through loss of constitutive activity. Patients (aged 4.0-15.1 years) had proportionate short stature (height -2.8 ± 0.5 SDS), failure to thrive with low appetite (n = 4), a mean serum insulin-like growth factor-I (IGF-I) of -1.6 ± 0.7 SDS, and a normal stimulated GH response. Nine patients received GH treatment, showing a height gain of 0.9 ± 0.4 SDS after 1 year and 1.5 ± 0.4 SDS after 2 years (n = 5).

CONCLUSION

This study combines phenotypical and functional data in a uniquely large group of children with short stature carrying GHSR variants, and shows their good response to GH treatment. The results strengthen the hypothesis of GHSR's role in GH secretion.

Obesity-Induced PVAT Dysfunction and Atherosclerosis Development: The Role of GHSR-1a in Increased Macrophage Infiltration and Adipocytokine Secretion

In obesity, recent research revealed that increased expression of the growth hormone secretagogue receptor (GHSR) in macrophages plays a pivotal role in the development of meta-inflammation, promoting macrophage infiltration and pro-inflammatory polarization. This study aimed to examine the association between GHSR-1a expression in atherosclerotic plaques and adjacent perivascular adipose tissue (PVAT) from 11 patients with obesity and peripheral artery disease (PAD) who underwent revascularization procedures. Immunohistochemistry was used to assess the expression of CD68, CD80, and CD14, while tissue homogenate levels of adiponectin, leptin, IL-6, and CRP were quantified via ELISA. Serum markers of inflammation were also measured. Among patients with GHSR-1a-positive (+) macrophages in atherosclerotic plaques, we observed significantly higher white blood cell counts and platelet-to-lymphocyte ratios in serum, a lower adiponectin-to-leptin ratio, and elevated IL-6 levels in both arterial and PVAT homogenates. Our findings suggest a link between GHSR-1a and macrophage/monocyte infiltration, macrophage polarization, and adipocytokine secretion in atherosclerotic plaques associated with obesity-induced PVAT dysfunction.

Association between weight-adjusted waist index and Hashimoto's thyroiditis: insights from NHANES 2007-2012

Objective

While previous studies have explored the relationship between obesity and levels of thyroid autoantibodies, research using novel indicators such as weight-adjusted waist index (WWI) remains limited. This study aimed to evaluate the potential relationship between WWI and thyroid autoantibody levels, with the objective of improving our understanding of the links between central obesity and Hashimoto's thyroiditis (HT).

Methods

We conducted a cross-sectional study using data from the National Health and Nutrition Examination Survey (NHANES) cycles from 2007 to 2012. We analyzed the relationship between WWI and levels of thyroid peroxidase antibodies (TPOAb) and thyroglobulin antibodies (TgAb) through multivariate linear regression and subgroup analyses.

Results

The study included 7,056 participants with an average age of 49.71 ± 17.66 years, comprising 49.18% females. Mean WWI across the cohort was 11.04 ± 0.84. Analysis revealed a significant positive association between WWI and TPOAb levels (β: 4.78, 95% CI: 1.52, 8.05, p = 0.0041), which remained consistent across all multivariate linear regression models. In contrast, no significant correlation was found between WWI and TgAb levels after adjusting for covariates. Subgroup analysis stratified by gender demonstrated a notable gender-specific effect, where the positive correlation between WWI and TPOAb levels was evident only in females (β: 8.13, 95% CI: 4.14, 12.12, p < 0.0001).

Conclusion

This study used WWI as a novel indicator of central obesity and identified a strong association with HT, particularly notable in females. However, further high-quality studies are needed to confirm these findings and explore the underlying biological mechanisms.

Cross-talk of inflammation and cellular senescence: a new insight into the occurrence and progression of osteoarthritis

Osteoarthritis (OA) poses a significant challenge in orthopedics. Inflammatory pathways are regarded as central mechanisms in the onset and progression of OA. Growing evidence suggests that senescence acts as a mediator in inflammation-induced OA. Given the lack of effective treatments for OA, there is an urgent need for a clearer understanding of its pathogenesis. In this review, we systematically summarize the cross-talk between cellular senescence and inflammation in OA. We begin by focusing on the mechanisms and hallmarks of cellular senescence, summarizing evidence that supports the relationship between cellular senescence and inflammation. We then discuss the mechanisms of interaction between cellular senescence and inflammation, including senescence-associated secretory phenotypes (SASP) and the effects of pro- and anti-inflammatory interventions on cellular senescence. Additionally, we focus on various types of cellular senescence in OA, including senescence in cartilage, subchondral bone, synovium, infrapatellar fat pad, stem cells, and immune cells, elucidating their mechanisms and impacts on OA. Finally, we highlight the potential of therapies targeting senescent cells in OA as a strategy for promoting cartilage regeneration.

Brown adipose tissue: a potential target for aging interventions and healthy longevity

Brown Adipose Tissue (BAT) is a type of fat tissue that can generate heat and plays an important role in regulating body temperature and energy metabolism. Enhancing BAT activity through medication, exercise and other means has become a potential effective method for treating metabolic disorders. Recently, there has been increasing evidence suggesting a link between BAT and aging. As humans age, the volume and activity of BAT decrease, which may contribute to the development of age-related diseases. Multiple organelles signaling pathways have been reported to be involved in the aging process associated with BAT. Therefore, we aimed to review the evidence related to the association between aging process and BAT decreasing, analyze the potential of BAT as a predictive marker for age-related diseases, and explore potential therapeutic strategies targeting BAT for aging interventions and healthy longevity.

Central neural mechanisms of cancer cachexia

PURPOSE OF REVIEW

Cachexia is a devasting syndrome which impacts a large number of patients with cancer. This review aims to provide a comprehensive overview of the central mechanisms of cancer cachexia. In particular, it focuses on the role of the central nervous system (CNS), the melanocortin system, circulating hormones and molecules which are produced by and act on the CNS and the psychological symptoms of cancer cachexia.

RECENT FINDINGS

A growing body of evidence suggests that a central mechanism of action underpins this multi-system disorder. Recent research has focused on the role of neuroinflammation that drives the sickness behaviour seen in cancer cachexia, with emphasis on the role of the hypothalamus. Melanocortin receptor antagonists are showing promise in preclinical studies. There are also new pharmacological developments to overcome the short half-life of ghrelin. GDF-15 has been identified as a core target and trials of compounds that interfere with its signalling or its central receptor are underway.

SUMMARY

Understanding the central mechanisms of cancer cachexia is pivotal for enhancing treatment outcomes in patients. While emerging pharmacological interventions targeting these pathways have shown promise, further research is essential.

Innate immunity in peripheral tissues is differentially impaired under normal and endotoxic conditions in aging

Chronic low-grade inflammation is a hallmark of aging, aka "inflammaging", which is linked to a wide range of age-associated diseases. Immune dysfunction increases disease susceptibility, and increases morbidity and mortality of aging. Innate immune cells, including monocytes, macrophages and neutrophils, are the first responders of host defense and the key mediators of various metabolic and inflammatory insults. Currently, the understanding of innate immune programming in aging is largely fragmented. Here we investigated the phenotypic and functional properties of innate immune cells in various peripheral tissues of young and aged mice under normal and endotoxic conditions. Under the steady state, aged mice showed elevated pro-inflammatory monocytes/macrophages in peripheral blood, adipose tissue, liver, and colon. Under lipopolysaccharide (LPS)-induced inflammatory state, the innate immune cells of aged mice showed a different response to LPS stimulus than that of young mice. LPS-induced immune responses displayed differential profiles in different tissues and cell types. In the peripheral blood, when responding to LPS, the aged mice showed higher neutrophils, but lower pro-inflammatory monocytes than that in young mice. In the peritoneal fluid, while young mice exhibited significantly elevated pro-inflammatory neutrophils and macrophages in response to LPS, aged mice exhibited decreased pro-inflammatory neutrophils and variable cytokine responses in macrophages. In the adipose tissue, LPS induced less infiltrated neutrophils but more infiltrated macrophages in old mice than young mice. In the liver, aged mice showed a more robust increase of pro-inflammatory macrophages compared to that in young mice under LPS stimulation. In colon, macrophages showed relatively mild response to LPS in both young and old mice. We have further tested bone-marrow derived macrophages (BMDM) from young and aged mice, we found that BMDM from aged mice have impaired polarization, displaying higher expression of pro-inflammatory markers than those from young mice. These data collectively suggest that innate immunity in peripheral tissues is impaired in aging, and the dysregulation of immunity is tissue- and cell-dependent. Our findings in the rodent model underscore the complexity of aging immunity. Further investigation is needed to determine whether the immune profile observed in aged mice is applicable in age-associated diseases in humans.

Ghrelin/GHSR System in Depressive Disorder: Pathologic Roles and Therapeutic Implications

Depression is the most common chronic mental illness and is characterized by low mood, insomnia, and affective disorders. However, its pathologic mechanisms remain unclear. Numerous studies have suggested that the ghrelin/GHSR system may be involved in the pathophysiologic process of depression. Ghrelin plays a dual role in experimental animals, increasing depressed behavior and decreasing anxiety. By combining several neuropeptides and traditional neurotransmitter systems to construct neural networks, this hormone modifies signals connected to depression. The present review focuses on the role of ghrelin in neuritogenesis, astrocyte protection, inflammatory factor production, and endocrine disruption in depression. Furthermore, ghrelin/GHSR can activate multiple signaling pathways, including cAMP/CREB/BDNF, PI3K/Akt, Jak2/STAT3, and p38-MAPK, to produce antidepressant effects, given which it is expected to become a potential therapeutic target for the treatment of depression.

Common and uncommon mouse models of growth hormone deficiency

Mouse models of growth hormone deficiency (GHD) have provided important tools for uncovering the various actions of GH. Nearly 100 years of research using these mouse lines has greatly enhanced our knowledge of the GH/IGF-1 axis. Some of the shared phenotypes of the five "common" mouse models of GHD include reduced body size, delayed sexual maturation, decreased fertility, reduced muscle mass, increased adiposity, and enhanced insulin sensitivity. Since these common mouse lines outlive their normal-sized littermates - and have protection from age-associated disease - they have become important fixtures in the aging field. On the other hand, the twelve "uncommon" mouse models of GHD described herein have tremendously divergent health outcomes ranging from beneficial aging phenotypes (similar to those described for the common models) to extremely detrimental features (such as improper development of the CNS, numerous sensory organ defects, and embryonic lethality). Moreover, advancements in next generation sequencing technologies have led to the identification of an expanding array of genes that are recognized as causative agents to numerous rare syndromes with concomitant GHD. Accordingly, this review provides researchers with a comprehensive up-to-date collection of the common and uncommon mouse models of GHD that have been used to study various aspects of physiology and metabolism associated with multiple forms of GHD. For each mouse line presented, the closest comparable human syndromes are discussed providing important parallels to the clinic.

Genetic or pharmacological GHSR blockade has sexually dimorphic effects in rodents on a high-fat diet

The stomach-derived hormone ghrelin regulates essential physiological functions. The ghrelin receptor (GHSR) has ligand-independent actions; therefore, GHSR gene deletion may be a reasonable approach to investigate the role of this system in feeding behaviors and diet-induced obesity (DIO). Here, we investigate the effects of a long-term (12-month) high-fat (HFD) versus regular diet on obesity-related measures in global GHSR-KO and wild-type (WT) Wistar male and female rats. Our main findings are that the GHSR gene deletion protects against DIO and decreases food intake during HFD in male but not in female rats. GHSR gene deletion increases thermogenesis and brain glucose uptake in male rats and modifies the effects of HFD on brain glucose metabolism in a sex-specific manner, as assessed with small animal positron emission tomography. We use RNA-sequencing to show that GHSR-KO rats have upregulated expression of genes responsible for fat oxidation in brown adipose tissue. Central administration of a novel GHSR inverse agonist, PF-5190457, attenuates ghrelin-induced food intake, but only in male, not in female mice. HFD-induced binge-like eating is reduced by inverse agonism in both sexes. Our results support GHSR as a promising target for new pharmacotherapies for obesity.

GHSR Deletion in β-Cells of Male Mice: Ineffective in Obesity, but Effective in Protecting against Streptozotocin-Induced β-Cell Injury in Aging

Insulin secretion from pancreatic β cells is a key pillar of glucose homeostasis, which is impaired under obesity and aging. Growth hormone secretagogue receptor (GHSR) is the receptor of nutrient-sensing hormone ghrelin. Previously, we showed that β-cell GHSR regulated glucose-stimulated insulin secretion (GSIS) in young mice. In the current study, we further investigated the effects of GHSR on insulin secretion in male mice under diet-induced obesity (DIO) and streptozotocin (STZ)-induced β-cell injury in aging. β-cell-specific-Ghsr-deficient (Ghsr-βKO) mice exhibited no glycemic phenotype under DIO but showed significantly improved ex vivo GSIS in aging. We also detected reduced insulin sensitivity and impaired insulin secretion during aging both in vivo and ex vivo. Accordingly, there were age-related alterations in expression of glucose transporter, insulin signaling pathway, and inflammatory genes. To further determine whether GHSR deficiency affected β-cell susceptibility to acute injury, young, middle-aged, and old Ghsr-βKO mice were subjected to STZ. We found that middle-aged and old Ghsr-βKO mice were protected from STZ-induced hyperglycemia and impaired insulin secretion, correlated with increased expression of insulin signaling regulators but decreased pro-inflammatory cytokines in pancreatic islets. Collectively, our findings indicate that β-cell GHSR has a major impact on insulin secretion in aging but not obesity, and GHSR deficiency protects against STZ-induced β-cell injury in aging.

Nutrient-sensing growth hormone secretagogue receptor in macrophage programming and meta-inflammation

OBJECTIVE

Obesity-associated chronic inflammation, aka meta-inflammation, is a key pathogenic driver for obesity-associated comorbidity. Growth hormone secretagogue receptor (GHSR) is known to mediate the effects of nutrient-sensing hormone ghrelin in food intake and fat deposition. We previously reported that global Ghsr ablation protects against diet-induced inflammation and insulin resistance, but the site(s) of action and mechanism are unknown. Macrophages are key drivers of meta-inflammation. To unravel the role of GHSR in macrophages, we generated myeloid-specific Ghsr knockout mice (LysM-Cre;Ghsrf/f).

METHODS

LysM-Cre;Ghsrf/f and control Ghsrf/f mice were subjected to 5 months of high-fat diet (HFD) feeding to induce obesity. In vivo, metabolic profiling of food intake, physical activity, and energy expenditure, as well as glucose and insulin tolerance tests (GTT and ITT) were performed. At termination, peritoneal macrophages (PMs), epididymal white adipose tissue (eWAT), and liver were analyzed by flow cytometry and histology. For ex vivo studies, bone marrow-derived macrophages (BMDMs) were generated from the mice and treated with palmitic acid (PA) or lipopolysaccharide (LPS). For in vitro studies, macrophage RAW264.7 cells with Ghsr overexpression or Insulin receptor substrate 2 (Irs2) knockdown were studied.

RESULTS

We found that Ghsr expression in PMs was increased under HFD feeding. In vivo, HFD-fed LysM-Cre;Ghsrf/f mice exhibited significantly attenuated systemic inflammation and insulin resistance without affecting food intake or body weight. Tissue analysis showed that HFD-fed LysM-Cre;Ghsrf/f mice have significantly decreased monocyte/macrophage infiltration, pro-inflammatory activation, and lipid accumulation, showing elevated lipid-associated macrophages (LAMs) in eWAT and liver. Ex vivo, Ghsr-deficient macrophages protected against PA- or LPS-induced pro-inflammatory polarization, showing reduced glycolysis, increased fatty acid oxidation, and decreased NF-κB nuclear translocation. At molecular level, GHSR metabolically programs macrophage polarization through PKA-CREB-IRS2-AKT2 signaling pathway.

CONCLUSIONS

These novel results demonstrate that macrophage GHSR plays a key role in the pathogenesis of meta-inflammation, and macrophage GHSR promotes macrophage infiltration and induces pro-inflammatory polarization. These exciting findings suggest that GHSR may serve as a novel immunotherapeutic target for the treatment of obesity and its associated comorbidity.

Role and molecular mechanism of ghrelin in degenerative musculoskeletal disorders

Ghrelin is a brain-gut peptide, and the first 28-peptide that was found in the gastric mucosa. It has a growth hormone (GH)-releasing hormone-like effect and can potently promote the release of GH from pituitary GH cells; however, it is unable to stimulate GH synthesis. Therefore, ghrelin is believed to play a role in promoting bone growth and development. The correlation between ghrelin and some degenerative diseases of the musculoskeletal system has been reported recently, and ghrelin may be one of the factors influencing degenerative pathologies, such as osteoporosis, osteoarthritis, sarcopenia and intervertebral disc degeneration. With population ageing, the risk of health problems caused by degenerative diseases of the musculoskeletal system gradually increases. In this article, the roles of ghrelin in musculoskeletal disorders are summarized to reveal the potential effects of ghrelin as a key target in the treatment of related bone and muscle diseases and the need for further research.

Effect of laparoscopic sleeve gastrectomy on platelet count and mean platelet volume

Objective

Several studies have reported an increase in platelet (PLT) count with chronic inflammation in the presence of obesity. Mean platelet volume (MPV) is an important marker for PLT activity. Our study aims to demonstrate if laparoscopic sleeve gastrectomy (LSG) has any effect on PLT, MPV and white blood cells (WBCs).

Methods

A total of 202 patients undergoing LSG for morbid obesity between January 2019 and March 2020 who completed at least 1 year of follow-up were included in the study. Patients' characteristics and laboratory parameters were recorded preoperatively and were compared in the 6th and 12th months.

Results

Two hundred and two patients (50% - female) with a mean age of 37.5 ± 12.2 years and mean pre-operative body mass index (BMI) of 43 (34.1-62.5) kg/m2 underwent LSG. BMI regressed to 28.2 ± 4.5 kg/m2 at 1 year after LSG (P < 0.001). The mean PLT count, MPV and WBC during the pre-operative period were 293.2 ± 70.3 103 cells/μL, 10.22 ± 0.9 fL and 7.8 ± 1.9 103 cells/μL, respectively. A significant decrease was seen in mean PLT count, with 257.3 ± 54.2 103cell/μL (P < 0.001) at 1 year post-LSG. The mean MPV was increased at 6 months 10.5 ± 1.2 fL (P < 0.001) and remained unchanged at 1 year 10.3 ± 1.3 fL (P = 0.9). The mean WBC levels were significantly decreased with 6.5 ± 1.7 103 cells/μL (P < 0.001) at 1 year. At the end of the follow-up, weight loss showed no correlation with PLT and MPV (P = 0.42, P = 0.32).

Conclusion

Our study has shown a significant decrease in circulating PLT and WBC levels while MPV remained unchanged after LSG.

Impact of intestinal microenvironments in obesity and bariatric surgery on shaping macrophages

Obesity is associated with alterations in tissue composition, systemic cellular metabolism, and low-grade chronic inflammation. Macrophages are heterogenous innate immune cells ubiquitously localized throughout the body and are key components of tissue homeostasis, inflammation, wound healing, and various disease states. Macrophages are highly plastic and can switch their phenotypic polarization and change function in response to their local environments. Here, we discuss how obesity alters the intestinal microenvironment and potential key factors that can influence intestinal macrophages as well as macrophages in other organs, including adipose tissue and hematopoietic organs. As bariatric surgery can induce metabolic adaptation systemically, we discuss the potential mechanisms through which bariatric surgery reshapes macrophages in obesity.

In vivo corneal confocal microscopy as a non-invasive test to assess obesity induced small fibre nerve damage and inflammation

PURPOSE

To investigate small nerve fibre damage and inflammation at the level of the sub-basal nerve plexus (SNP) of severe obese patients and compare the results with those of healthy subjects.

METHODS

This cross-sectional, observational study investigated the data of 28 patients (14 out of 28 prediabetic or diabetic) with severe obesity (Body Mass Index; BMI ≥ 40) and 20 healthy subjects. Corneal nerve fibre density (CNFD), branch density (CNBD), fibre length (CNFL), nerve fibre area (CNFA), nerve fibre width (CNFW), and nerve fractal dimension (CNFrD) and dendritic cell (DC) density were evaluated using in vivo confocal microscopy (IVCM, Heidelberg Retinal Tomograph III Rostock Cornea Module). Automatic CCMetrics software (University of Manchester, UK) was used for quantitative analysis of SNP.

RESULTS

Mean age was 48.4±7.4 and 45.1 ± 5.8 in the control and obese group, respectively (p = 0.09). Mean BMI were 49.1 ± 7.8 vs. 23.3 ± 1.4 in obese vs. control group, respectively (p < 0.001). Mean CNFD, CNBD, CNFL, CNFA, CNFW were significantly reduced in obese group compared with those in the control group (always p < 0.05, respectively). There were no significant differences in any ACCMetrics parameters between prediabetic/diabetic and non-diabetic obese patients. Increased DC densities were detected in obese group compared with those in control group (p < 0.0001). There were significant correlations between BMI scores and SNP parameters.

CONCLUSION

Imaging with IVCM is a feasible, non-invasive method to detect and quantify occult corneal nerve damage and increased inflammation in patients with obesity. This study suggests that obesity may be a separate risk factor for peripheral neuropathy regardless of DM.

Nutrient-Sensing Ghrelin Receptor in Macrophages Modulates Bisphenol A-Induced Intestinal Inflammation in Mice

Bisphenols are environmental toxins with endocrine disruptor activity, yet bisphenol A (BPA) and its analogs are still widely used in manufacturing plastic products. There is evidence showing that BPA elicits inflammation in humans and animals, but the target cell types of BPA are not well understood. In this study, we sought to determine BPA's direct effect on macrophages and BPA immunotoxicity in mouse intestine. Ghrelin is an important nutrient-sensing hormone, acting through its receptor growth hormone secretagogue receptor (GHSR) to regulate metabolism and inflammation. We found that BPA promotes intestinal inflammation, showing increased infiltrating immune cells in colons and enhanced expression of Ghsr and pro-inflammatory cytokines and chemokines, such as Il6 and Ccl2, in colonic mucosa. Moreover, we found that both long- and short-term BPA exposure elevated pro-inflammatory monocytes and macrophages in mouse peripheral blood mononuclear cells (PBMC) and peritoneal macrophages (PM), respectively. To determine the role of GHSR in BPA-mediated inflammation, we generated Ghsr deletion mutation in murine macrophage RAW264.7 using CRISPR gene editing. In wild-type RAW264.7 cells, the BPA exposure promotes macrophage pro-inflammatory polarization and increases Ghsr and cytokine/chemokine Il6 and Ccl2 expression. Interestingly, Ghsr deletion mutants showed a marked reduction in pro-inflammatory cytokine/chemokine expression in response to BPA, suggesting that GHSR is required for the BPA-induced pro-inflammatory response. Further understanding how nutrient-sensing GHSR signaling regulates BPA intestinal immunotoxicity will help design new strategies to mitigate BPA immunotoxicity and provide policy guidance for BPA biosafety.

Ghrelin Modulates Differential Expression of Genes Relevant to Immune Activities and Antimicrobial Peptides in Primary Head Kidney Cells of Rainbow Trout (Oncorhynchus mykiss)

Ghrelin is a peptide hormone/cytokine that regulates metabolic processes and plays essential roles in the immune system. To evaluate the immunomodulatory actions of ghrelin isoforms in rainbow trout (RT), an in vitro model was utilized with primary cells isolated from fish head kidney (HKD). These RT-HKD cells were treated with synthetic rainbow trout ghrelin and its truncated isoform, desVRQ-ghrelin, over time (0, 2, 4, and 24 h). Reverse transcriptase-coupled qPCR was used to measure the differential expression patterns of genes relevant to various immune processes and genes of antimicrobial peptides. Ghrelin isoform treatments resulted in functional perturbations that displayed overlapping and divergent patterns of gene expression. The differing actions between the two ghrelin isoforms on various assessed genes, and at differing time points, suggested that the two analogs may activate unique pathways, thereby eliciting distinct responses in fish immunity.

Ablation of Ghrelin Receptor Mitigates the Metabolic Decline of Aging Skeletal Muscle

The orexigenic hormone ghrelin has multifaceted roles in health and disease. We have reported that ablation of the ghrelin receptor, growth hormone secretagogue receptor (GHS-R), protects against metabolic dysfunction of adipose tissues in aging. Our further observation interestingly revealed that GHS-R deficiency phenocopies the effects of myokine irisin. In this study, we aim to determine whether GHS-R affects the metabolic functions of aging skeletal muscle and whether GHS-R regulates the muscular functions via irisin. We first studied the expression of metabolic signature genes in gastrocnemius muscle of young, middle-aged and old mice. Then, old GHS-R knockout (Ghsr-/-) mice and their wild type counterparts were used to assess the impact of GHS-R ablation on the metabolic characteristics of gastrocnemius and soleus muscle. There was an increase of GHS-R expression in skeletal muscle during aging, inversely correlated with the decline of metabolic functions. Remarkedly the muscle of old GHS-R knockout (Ghsr-/-) mice exhibited a youthful metabolic profile and better maintenance of oxidative type 2 muscle fibers. Furthermore, old Ghsr-/- mice showed improved treadmill performance, supporting better functionality. Also intriguing to note was the fact that old GHS-R-ablated mice showed increased expression of the irisin precursor FNDC5 in the muscle and elevated plasma irisin levels in circulation, which supports a potential interrelationship between GHS-R and irisin. Overall, our work suggests that GHS-R has deleterious effects on the metabolism of aging muscle, which may be at least partially mediated by myokine irisin.

Ainsliadimer C, a disesquiterpenoid isolated from Ainsliaea macrocephala, ameliorates inflammatory responses in adipose tissue via Sirtuin 1-NLRP3 inflammasome axis

Interleukin-1β (IL-1β), a key pro-inflammatory cytokine, is majorly produced by macrophages through NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome, which has been identified as the culprit to deteriorate the inflammatory crosstalk between macrophages and adipocytes. Ainsliadimer C (AC) is a disesquiterpenoid isolated from Ainsliaea macrocephala. In the current study, we investigated the effects of AC on adipose tissue inflammation in co-culture of macrophages and adipocytes in vitro as well as in LPS-treated mice in vivo. We showed that AC (20-80 µM) dose-dependently inhibited the secretion of IL-1β from LPS plus ATP-stimulated THP-1 macrophages by inhibiting the activation of NLRP3 inflammasome. Furthermore, we found that AC treatment activated NAD⁺-dependent deacetylase Sirtuin 1 (SIRT1), resulting in reduced acetylation level of NLRP3. Molecular modeling analysis revealed that binding of AC to sirtuin-activating compound-binding domain increased the affinity of the substrate to the catalytic domain of SIRT1. Moreover, AC (80 µM) significantly attenuated macrophage-conditioned medium-induced inflammatory responses in 3T3-L1 adipocytes. In LPS-induced acute inflammatory mice, administration of AC (20, 60 mg·kg^-1·d^-1, ip) for 5 days significantly suppressed the pro-inflammatory cytokine levels in serum and epididymal white adipose tissue (eWAT), attenuated macrophage infiltration into eWAT, and mitigated adipose tissue inflammation. The beneficial effects of AC were blocked by co-administration of a selective SIRT1 inhibitor EX-527 (10 mg·kg^-1·d^-1). Taken together, AC suppresses NLRP3-mediated IL-1β secretion through activating SIRT1, leading to attenuated inflammation in macrophages and adipose tissue, which might be a candidate to treat obesity-associated metabolic diseases.

Ghrelin deficiency sex-dependently affects food intake, locomotor activity, and adipose and hepatic gene expression in a binge-eating mouse model

Binge-eating disorder is the most prevalent eating disorder diagnosed, affecting three times more women than men. Ghrelin stimulates appetite and reward signaling, and loss of its receptor reduces binge-eating behavior in male mice. Here, we examined the influence of ghrelin itself on binge-eating behavior in both male and female mice. Five-wk-old wild-type (WT) and ghrelin-deficient (Ghrl^-/-) mice were housed individually in indirect calorimetry cages for 9 wks. Binge-like eating was induced by giving mice ad libitum chow, but time-restricted access to a Western-style diet (WD; 2 h access, 3 days/wk) in the light phase (BE); control groups received ad libitum chow (CO), or ad libitum access to both diets (CW). All groups of BE mice showed binge-eating behavior, eating up to 60% of their 24-h intake during the WD access period. Subsequent dark phase chow intake was decreased in Ghrl^-/- mice and remained decreased in Ghrl^-/- females on nonbinge days. Also, nonbinge day locomotor activity was lower in Ghrl^-/- than in WT BE females. Upon euthanasia, Ghrl^-/- BE mice weighed less and had a lower lean body mass percentage than WT BE mice. In BE and CW groups, ghrelin and sex altered the expression of genes involved in lipid processing, thermogenesis, and aging in white adipose tissue and livers. We conclude that, although ghrelin deficiency does not hamper the development of binge-like eating, it sex-dependently alters food intake timing, locomotor activity, and metabolism. These results add to the growing body of evidence that ghrelin signaling is sexually dimorphic.NEW & NOTEWORTHY Ghrelin, a peptide hormone secreted from the gut, is involved in hunger and reward signaling, which are altered in binge-eating disorder. Although sex differences have been described in both binge-eating and ghrelin signaling, this interaction has not been fully elucidated. Here, we show that ghrelin deficiency affects the behavior and metabolism of mice in a binge-like eating paradigm, and that the sex of the mice impacts the magnitude and direction of these effects.

Transcriptomic landscape of hepatic lymph nodes, peripheral blood lymphocytes and spleen of swamp buffaloes infected with the tropical liver fluke Fasciola gigantica

The tropical liver fluke Fasciola gigantica is a parasitic helminth that has been frequently reported to infect mammals, typically involving water buffaloes. In this study, we characterized the tissue transcriptional landscape of buffaloes following infection by F. gigantica. RNAs were isolated from hepatic lymph nodes (hLNs), peripheral blood lymphocytes (pBLs), and spleen at 3-, 42- and 70-days post-infection (dpi), and all samples were subjected to RNA sequencing analyses. At 3 dpi, 2603, 460, and 162 differentially expressed transcripts (DETs) were detected in hLNs, pBLs, and spleen, respectively. At 42 dpi, 322, 937, and 196 DETs were detected in hLNs, pBLs, and spleen, respectively. At 70 dpi, 376, 334, and 165 DETs were detected in hLNs, pBLs, and spleen, respectively. Functional enrichment analysis identified upregulated immune-related pathways in the infected tissues involved in innate and adaptive immune responses, especially in hLNs at 42 and 70 dpi, and pBLs at 3 and 42 dpi. The upregulated transcripts in spleen were not enriched in any immune-related pathway. Co-expression network analysis further identified transcriptional changes associated with immune response to F. gigantica infection. Receiver operating characteristic (ROC) curve analysis showed that 107 genes in hLNs, 32 genes in pBLs, and 36 genes in spleen correlated with F. gigantica load. These findings provide new insight into molecular mechanisms and signaling pathways associated with F. gigantica infection in buffaloes.

Fasciola gigantica is a socioeconomically important tropical liver fluke of mammals, causing fascioliasis–a neglected tropical disease. In the present study, RNA sequencing and bioinformatic approach were employed to explore the global transcriptional changes of hepatic lymph nodes (hLNs), peripheral blood lymphocytes (pBLs), and spleen of water buffaloes during F. gigantica infection at 3-, 42-, and 70-days post-infection (dpi). The results revealed significant transcriptional upregulation of genes associated with innate and adaptive immune responses in infected hLNs (42 and 70 dpi) and pBLs (3 and 42 dpi). However, downregulation of transcripts involved in immune response was detected in pBLs at 70 dpi. The downregulated transcripts were enriched in metabolic pathways, such as drug metabolism-cytochrome P450 in infected hLNs at 3 dpi. These findings provide new insight into the pathogenesis of F. gigantica in its natural mammalian host.

Ghrelin and Cancer: Examining the Roles of the Ghrelin Axis in Tumor Growth and Progression

Ghrelin, a hormone produced and secreted from the stomach, is prim arily known as an appetite stimulant. Recently, it has emerged as a potential regulator/biomarker of cancer progression. Inconsistent results on this subject make this body of literature difficult to interpret. Here, we attempt to identify commonalities in the relationships between ghrelin and various cancers, and summarize important considerations for future research. The main players in the ghrelin family axis are unacylated ghrelin (UAG), acylated ghrelin (AG), the enzyme ghrelin O-acyltransferase (GOAT), and the growth hormone secretagogue receptor (GHSR). GOAT is responsible for the acylation of ghrelin, after which ghrelin can bind to the functional ghrelin receptor GHSR-1a to initiate the activation cascade. Splice variants of ghrelin also exist, with the most prominent being In1-ghrelin. In this review, we focus primarily on the potential of In1-ghrelin as a biomarker for cancer progression, the unique characteristics of UAG and AG, the importance of the two known receptor variants GHSR-1a and 1b, as well as the possible mechanisms through which the ghrelin axis acts. Further understanding of the role of the ghrelin axis in tumor cell proliferation could lead to the development of novel therapeutic approaches for various cancers.

Novel Role of Ghrelin Receptor in Gut Dysbiosis and Experimental Colitis in Aging

Chronic low-grade inflammation is a hallmark of aging, which is now coined as inflamm-aging. Inflamm-aging contributes to many age-associated diseases such as obesity, type 2 diabetes, cardiovascular disease, and inflammatory bowel disease (IBD). We have shown that gut hormone ghrelin, via its receptor growth hormone secretagogue receptor (GHS-R), regulates energy metabolism and inflammation in aging. Emerging evidence suggests that gut microbiome has a critical role in intestinal immunity of the host. To determine whether microbiome is an integral driving force of GHS-R mediated immune-metabolic homeostasis in aging, we assessed the gut microbiome profiles of young and old GHS-R global knockout (KO) mice. While young GHS-R KO mice showed marginal changes in Bacteroidetes and Firmicutes, aged GHS-R KO mice exhibited reduced Bacteroidetes and increased Firmicutes, featuring a disease-susceptible microbiome profile. To further study the role of GHS-R in intestinal inflammation in aging, we induced acute colitis in young and aged GHS-R KO mice using dextran sulfate sodium (DSS). The GHS-R KO mice showed more severe disease activity scores, higher proinflammatory cytokine expression, and decreased expression of tight junction markers. These results suggest that GHS-R plays an important role in microbiome homeostasis and gut inflammation during aging; GHS-R suppression exacerbates intestinal inflammation in aging and increases vulnerability to colitis. Collectively, our finding reveals for the first time that GHS-R is an important regulator of intestinal health in aging; targeting GHS-R may present a novel therapeutic strategy for prevention/treatment of aging leaky gut and inflammatory bowel disease.

Metabolic Hormones Modulate Macrophage Inflammatory Responses

Simple Summary

Macrophages are a type of immune cell which play an important role in the development of cancer. Obesity increases the risk of cancer and obesity also causes disruption to the normal levels of hormones that are produced to coordinate metabolism. Recent research now shows that these metabolic hormones also play important roles in macrophage immune responses and so through macrophages, disrupted metabolic hormone levels may promote cancer. This review article aims to highlight and summarise these recent findings so that the scientific community may better understand how important this new area of research is, and how these findings can be capitalised on for future scientific studies.

Abstract

Macrophages are phagocytotic leukocytes that play an important role in the innate immune response and have established roles in metabolic diseases and cancer progression. Increased adiposity in obese individuals leads to dysregulation of many hormones including those whose functions are to coordinate metabolism. Recent evidence suggests additional roles of these metabolic hormones in modulating macrophage inflammatory responses. In this review, we highlight key metabolic hormones and summarise their influence on the inflammatory response of macrophages and consider how, in turn, these hormones may influence the development of different cancer types through the modulation of macrophage functions.

GHS-R suppression in adipose tissues protects against obesity and insulin resistance by regulating adipose angiogenesis and fibrosis

BACKGROUND/OBJECTIVES

Ghrelin is an orexigenic hormone that increases food intake, adiposity, and insulin resistance through its receptor Growth Hormone Secretagogue Receptor (GHS-R). We previously showed that ghrelin/GHS-R signaling has important roles in regulation of energy homeostasis, and global deletion of GHS-R reduces obesity and improves insulin sensitivity by increasing thermogenesis. However, it is unknown whether GHS-R regulates thermogenic activation in adipose tissues directly.

METHODS

We generated a novel adipose tissue-specific GHS-R deletion mouse model and characterized the mice under regular diet (RD) and high-fat diet (HFD) feeding. Body composition was measured by Echo MRI. Metabolic profiling was determined by indirect calorimetry. Response to environmental stress was assessed using a TH-8 temperature monitoring system. Insulin sensitivity was evaluated by glucose and insulin tolerance tests. Tissue histology was analyzed by hematoxylin/eosin and immunofluorescent staining. Expression of genes involved in thermogenesis, angiogenesis and fibrosis in adipose tissues were analyzed by real-time PCR.

RESULTS

Under RD feeding, adipose tissue-specific GHS-R deletion had little or no impact on metabolic parameters. However, under HFD feeding, adipose tissue-specific GHS-R deletion attenuated diet-induced obesity and insulin resistance, showing elevated physical activity and heat production. In addition, adipose tissue-specific GHS-R deletion increased expression of master adipose transcription regulator of peroxisome proliferator-activated receptor (PPAR) γ1 and adipokines of adiponectin and fibroblast growth factor (FGF) 21; and differentially modulated angiogenesis and fibrosis evident in both gene expression and histological analysis.

CONCLUSIONS

These results show that GHS-R has cell-autonomous effects in adipocytes, and suppression of GHS-R in adipose tissues protects against diet-induced obesity and insulin resistance by modulating adipose angiogenesis and fibrosis. These findings suggest adipose GHS-R may constitute a novel therapeutic target for treatment of obesity and metabolic syndrome.

Stimulation of endogenous pulsatile growth hormone secretion by activation of growth hormone secretagogue receptor reduces the fat accumulation and improves the insulin sensitivity in obese mice

Obese individuals often show low growth hormone (GH) secretion, which leads to reduced lipid mobilization and further fat accumulation. Pharmacological approaches to increase GH levels in obese individuals by GH injection or GH-releasing hormone receptor agonist showed promising effects on fat reduction. However, side effects on glucose metabolism and the heavy costs on making large peptides hindered their clinical application. Here, we tested whether stimulation of endogenous GH secretion by a synthetic GH secretagogue receptor (GHSR) agonist, hexarelin, improved the metabolism in a hyperphagic obese mouse model. Male melanocortin 4 receptor knockout mice (MC4RKO) were pair-fed and received continuous hexarelin (10.56 μg/day) or vehicle infusion by an osmotic pump for 3-4 weeks. Hexarelin treatment significantly increased the pulsatile GH secretion without detectable alteration on basal GH secretion in MC4RKO mice. The treated mice showed increased lipolysis and lipid oxidation in the adipose tissue, and reduced de novo lipogenesis in the liver, leading to reduced visceral fat mass, reduced triglyceride content in liver, and unchanged circulating free fatty acid levels. Importantly, hexarelin treatment improved the whole-body insulin sensitivity but did not alter glucose tolerance, insulin levels, or insulin-like growth factor 1 (IGF-1) levels. The metabolic effects of hexarelin were likely through the direct action of GH, as indicated by the increased expression level of genes involved in GH signaling pathways in visceral adipose tissues and liver. In conclusion, hexarelin treatment stimulated the pulsatile GH secretion and reduced the fat accumulation in visceral depots and liver in obese MC4RKO mice with improved insulin sensitivity without altered levels of insulin or IGF-1. It provides evidence for managing obesity by enhancing pulsatile GH secretion through activation of GHSR in the pituitary gland.

Potential Antioxidative, Anti-inflammatory and Immunomodulatory Effects of Ghrelin, an Endogenous Peptide from the Stomach in SARS-CoV2 Infection

The current COVID-19 pandemic is one of the most devastating events in recent history. The respiratory effects of this disease include acute respiratory distress syndrome, systemic inflammation, cytokine storm, and pulmonary fibrosis. Ghrelin, an endogenous ligand for the growth hormone secretagogue receptor, is a peptide hormone secreted mainly by the stomach. Interestingly, ghrelin possesses promising antioxidant, anti-and inflammatory effects, making it an attractive agent to reduce the complications of the SARS-CoV-2. In addition, ghrelin exerts a wide range of immunomodulatory and anti-inflammatory effects and can mitigate the uncontrolled cytokine production responsible for acute lung injury by upregulating PPARγ and down-regulating NF-κB expression. Ghrelin has also been reported to enhance Nrf2 expression in inflammatory conditions which led to the suppression of oxidative stress. The current opinion summarizes the evidence for the possible pharmacological benefits of ghrelin in the therapeutic management of SARS-CoV-2 infection.

GHS-R in brown fat potentiates differential thermogenic responses under metabolic and thermal stresses

In response to cold or diet, fatty acids are dissipated into heat through uncoupling protein 1 (UCP1) in brown adipose tissue (BAT). This process is termed non-shivering thermogenesis, which is important for body temperature maintenance and contributes to obesity pathogenesis. Thermogenic enhancement has been considered a promising anti-obesity strategy. Ghrelin and its receptor Growth Hormone Secretagogue Receptor (GHS-R) have critical roles in energy intake, nutrient sensing, and lipid metabolism. We previously reported that global Ghsr-knockout mice have increased energy expenditure due to enhanced thermogenesis. To determine the site of action for GHS-R mediated thermogenesis, we generated brown adipocyte-specific Ghsr knockout mice (UCP1-CreER/Ghsrf/f) and assessed thermogenic responses under regular diet (RD) fed homeostatic metabolic state or high-fat diet (HFD) fed metabolically-impaired obese state, under normal or cold housing environment. Under a RD-feeding, UCP1-CreER/Ghsrf/f mice showed increased body fat and a slightly elevated core body temperature under cold but not under normal temperature. Consistently, the expression of thermogenic genes in BAT of RD-fed UCP1-CreER/Ghsrf/f mice was increased in reposes to cold. Under HFD feeding, HFD-fed UCP1-CreER/Ghsrf/f mice showed no difference in body fat or body temperature under either normal or cold exposure. Interestingly, the expression of thermogenic genes in BAT of HFD-fed UCP1-CreER/Ghsrf/f mice was upregulated under normal temperature but downregulated under cold exposure. Overall, our data show that GHS-R has cell-autonomous effect in brown adipocytes, and GHS-R regulates BAT thermogenic activity in a temperature- and metabolic state-dependent manner. The thermogenic effect of GHS-R in BAT is more pronounced in cold environment and differentially variable based on metabolic state; under cold exposure, GHS-R inhibition in BAT activates thermogenesis under homeostatic state but suppresses thermogenesis under obese state. Our finding collectively suggests that GHS-R in BAT, acting as a "metabolic thermostat", differentially regulates thermogenesis in response to different metabolic and thermal stimuli.

Ghrelin ameliorates nonalcoholic steatohepatitis induced by chronic low-grade inflammation via blockade of Kupffer cell M1 polarization

Whether the stomach influences the progression of nonalcoholic steatohepatitis (NASH) remains largely unknown. Ghrelin, a 28-amino acid gastric hormone, is critical for the regulation of energy metabolism and inflammation. We investigated whether ghrelin affects the progression of NASH. NASH was induced with lipopolysaccharide (LPS; 240 μg/kg/day) in male C57BL/6J mice with high-fat diet (HFD). Ghrelin (11 nmol/kg/day) was administrated by a subcutaneous mini-pump. Liver steatosis, inflammation, and fibrosis were assessed. Kupffer cells and hepatocytes isolated from wild type, GHSR1a^-/- or PPARγ^+/- mice were cocultured to determine the cellular and molecular mechanism by which ghrelin ameliorates NASH. A low concentration of LPS activates the Kupffer cells, leading to the development of NASH in mice fed HFD. Ghrelin blocked the progression of NASH induced by LPS via GHSR1a-mediated attenuation of Kupffer cells M1 polarization. GHSR1a was detected in Kupffer cells isolated from wild-type mice but not in GHSR1a deficient animals. Upon binding with ghrelin, internalization of GHSR1a occurred. Ghrelin reduced levels of tumor necrosis factor-α and inducible nitricoxide synthase while increasing Arg1 in Kupffer cells treated with LPS. Ghrelin markedly attenuated the upregulation of lipid accumulation induced by the supernatant of Kupffer cells under both basal and LPS-treated conditions. Deficiency of PPARγ significantly reduced the effect of LPS on the hepatic steatosis in mice and in cultured hepatocytes. Our studies indicate that the stomach may improve the development of NASH via ghrelin. Ghrelin may serve as a marker and therapeutic target for NASH.

The drug likeness analysis of anti-inflammatory clerodane diterpenoids

Inflammation is an active defense response of the body against external stimuli. Long term low-grade inflammation has been considered as a deteriorated factor for aging, cancer, neurodegeneration and metabolic disorders. The clinically used glucocorticoids and non-steroidal anti-inflammatory drugs are not suitable for chronic inflammation. Therefore, it's urgent to discover and develop new effective and safe drugs to attenuate inflammation. Clerodane diterpenoids, a class of bicyclic diterpenoids, are widely distributed in plants of the Labiatae, Euphorbiaceae and Verbenaceae families, as well as fungi, bacteria, and marine sponges. Dozens of anti-inflammatory clerodane diterpenoids have been identified on different assays, both in vitro and in vivo. In the current review, the up-to-date research progresses of anti-inflammatory clerodane diterpenoids were summarized, and their druglikeness was analyzed, which provided the possibility for further development of anti-inflammatory drugs.

Corneal dysfunction precedes the onset of hyperglycemia in a mouse model of diet-induced obesity

PURPOSE

The purpose of this study was to use a mouse model of diet-induced obesity to determine if corneal dysfunction begins prior to the onset of sustained hyperglycemia and if the dysfunction is ameliorated by diet reversal.

METHODS

Six-week-old male C57BL/6 mice were fed a high fat diet (HFD) or a normal diet (ND) for 5-15 weeks. Diet reversal (DiR) mice were fed a HFD for 5 weeks, followed by a ND for 5 or 10 weeks. Corneal sensitivity was determined using aesthesiometry. Corneal cytokine expression was analyzed using a 32-plex Luminex assay. Excised corneas were prepared for immunofluorescence microscopy to evaluate diet-induced changes and wound healing. For wounding studies, mice were fed a HFD or a ND for 10 days prior to receiving a central 2mm corneal abrasion.

RESULTS

After 10 days of HFD consumption, corneal sensitivity declined. By 10 weeks, expression of corneal inflammatory mediators increased and nerve density declined. While diet reversal restored nerve density and sensitivity, the corneas remained in a heightened inflammatory state. After 10 days on the HFD, corneal circadian rhythms (limbal neutrophil accumulation, epithelial cell division and Rev-erbα expression) were blunted. Similarly, leukocyte recruitment after wounding was dysregulated and accompanied by delays in wound closure and nerve recovery.

CONCLUSION

In the mouse, obesogenic diet consumption results in corneal dysfunction that precedes the onset of sustained hyperglycemia. Diet reversal only partially ameliorated this dysfunction, suggesting a HFD diet may have a lasting negative impact on corneal health that is resistant to dietary therapeutic intervention.

Ghrelin/GHS-R1a signaling plays different roles in anxiety-related behaviors after acute and chronic caloric restriction

The brain-gut hormone ghrelin and its receptor GHS-R1a, the growth hormone secretagogue receptor 1a, regulates diverse functions of central nervous system including stress response and mood. Both acute and chronic caloric restrictions (CR) were reported to increase endogenous ghrelin level meanwhile regulate anxiety-related behaviors; however, the causal relationship between CR-induced ghrelin elevation and anxiety are not fully established. Here, we introduced an acute (24 h) and a chronic (10wks) CR procedure to both GHS-R1a KO (Ghsr^-/-) mice and WT (Ghsr^+/+) littermates, and compared their anxiety-related behaviors. We found that acute CR induced anxiolytic and anti-despairing behaviors in Ghsr^+/+ mice but not in Ghsr^-/- mice. Ad-libitum refeeding abolished the effect of acute CR on anxiety-related behaviors. In contrast, chronic CR for 10wks facilitated despair-like behavior meanwhile inhibited anxiety-like behavior in Ghsr^+/+ mice. GHS-R1a deficiency rescued despair-like behavior while did not affect anxiolytic response induced by chronic CR. In addition, we found elevated interleukin-6 (IL-6) in serum of Ghsr^+/+ mice after chronic CR, but not in Ghsr^-/- mice. Altogether, our findings indicated that acute CR and chronic CR have different impacts on anxiety-related behaviors, and the former is dependent on ghrelin/GHS-R1a signaling while the latter may not always be. In addition, our findings suggested that GHS-R1a-dependent elevation in serum IL-6 might contribute to increased despair-like behavior in chronic CR state.

Ghrelin ameliorates tumor-induced adipose tissue atrophy and inflammation via Ghrelin receptor-dependent and -independent pathways

Adipose tissue (AT) atrophy is a hallmark of cancer cachexia contributing to increased morbidity/mortality. Ghrelin has been proposed as a treatment for cancer cachexia partly by preventing AT atrophy. However, the mechanisms mediating ghrelin's effects are incompletely understood, including the extent to which its only known receptor, GHSR-1a, is required for these effects. This study characterizes the pathways involved in AT atrophy in the Lewis Lung Carcinoma (LLC)-induced cachexia model and those mediating the effects of ghrelin in Ghsr ^+/+ and Ghsr ^-/- mice. We show that LLC causes AT atrophy by inducing anorexia, and increasing lipolysis, AT inflammation, thermogenesis and energy expenditure. These changes were greater in Ghsr ^-/-. Ghrelin administration prevented LLC-induced anorexia only in Ghsr ^+/+, but prevented WAT lipolysis, inflammation and atrophy in both genotypes, although its effects were greater in Ghsr ^+/+. LLC-induced increases in BAT inflammation, WAT and BAT thermogenesis, and energy expenditure were not affected by ghrelin. In conclusion, ghrelin ameliorates WAT inflammation, fat atrophy and anorexia in LLC-induced cachexia. GHSR-1a is required for ghrelin's orexigenic effect but not for its anti-inflammatory or fat-sparing effects.

Both ghrelin deletion and unacylated ghrelin overexpression preserve muscles in aging mice

Sarcopenia, the decline in muscle mass and functionality during aging, might arise from age-associated endocrine dysfunction. Ghrelin is a hormone circulating in both acylated (AG) and unacylated (UnAG) forms with anti-atrophic activity on skeletal muscle. Here, we show that not only lifelong overexpression of UnAG (Tg) in mice, but also the deletion of ghrelin gene (Ghrl KO) attenuated the age-associated muscle atrophy and functionality decline, as well as systemic inflammation. Yet, the aging of Tg and Ghrl KO mice occurs with different dynamics: while old Tg mice seem to preserve the characteristics of young animals, Ghrl KO mice features deteriorate with aging. However, young Ghrl KO mice show more favorable traits compared to WT animals that result, on the whole, in better performances in aged Ghrl KO animals. Treatment with pharmacological doses of UnAG improved muscle performance in old mice without modifying the feeding behavior, body weight, and adipose tissue mass. The antiatrophic effect on muscle mass did not correlate with modifications of protein catabolism. However, UnAG treatment induced a strong shift towards oxidative metabolism in muscle. Altogether, these data confirmed and expanded some of the previously reported findings and advocate for the design of UnAG analogs to treat sarcopenia.

Targeting of G-protein coupled receptors in sepsis

The Third International Consensus Definitions (Sepsis-3) define sepsis as life-threatening multi-organ dysfunction caused by a dysregulated host response to infection. Sepsis can progress to septic shock-an even more lethal condition associated with profound circulatory, cellular and metabolic abnormalities. Septic shock remains a leading cause of death in intensive care units and carries a mortality of almost 25%. Despite significant advances in our understanding of the pathobiology of sepsis, therapeutic interventions have not translated into tangible differences in the overall outcome for patients. Clinical trials of antagonists of various pro-inflammatory mediators in sepsis have been largely unsuccessful in the past. Given the diverse physiologic roles played by G-protein coupled receptors (GPCR), modulation of GPCR signaling for the treatment of sepsis has also been explored. Traditional pharmacologic approaches have mainly focused on ligands targeting the extracellular domains of GPCR. However, novel techniques aimed at modulating GPCR intracellularly through aptamers, pepducins and intrabodies have opened a fresh avenue of therapeutic possibilities. In this review, we summarize the diverse roles played by various subfamilies of GPCR in the pathogenesis of sepsis and identify potential targets for pharmacotherapy through these novel approaches.

Unacylated ghrelin stimulates fatty acid oxidation to protect skeletal muscle against palmitate-induced impairment of insulin action in lean but not high-fat fed rats

Background

Ghrelin is a gut hormone that spikes in circulation before mealtime. Recent findings suggest that both ghrelin isoforms stimulate skeletal muscle fatty acid oxidation, lending to the possibility that it may regulate skeletal muscle’s handling of meal-derived substrates. It was hypothesized in the current study that ghrelin may preserve muscle insulin response during conditions of elevated saturated fatty acid (palmitate) availability by promoting its oxidation.

Methods and results

Soleus muscle strips were isolated from male rats to determine the direct effects of ghrelin isoforms on fatty acid oxidation, glucose uptake and insulin signaling. We demonstrate that unacylated ghrelin (UnAG) is the more potent stimulator of skeletal muscle fatty acid oxidation. Both isoforms of ghrelin generally protected muscle from impaired insulin-mediated phosphorylation of AKT Ser⁴⁷³ and Thr³⁰⁸, as well as downstream phosphorylation of AS160 Ser⁵⁸⁸ during high palmitate exposure. However, only UnAG was able to preserve insulin-stimulated glucose uptake during exposure to high palmitate concentrations. The use of etomoxir, an irreversible inhibitor of carnitine palmitoyltransferase (CPT-1) abolished this protection, strongly suggesting that UnAG’s stimulation of fatty acid oxidation may be essential to this protection. To our knowledge, we are also the first to investigate the impact of a chronic high-fat diet on ghrelin’s actions in muscle. Following 6 wks of a high-fat diet, UnAG was unable to preserve insulin-stimulated signaling or glucose transport during an acute high palmitate exposure. UnAG was also unable to further stimulate 5′ AMP-activated protein kinase (AMPK) or fatty acid oxidation during high palmitate exposure. Corticotropin-releasing hormone receptor-2 (CRF-2R) content was significantly decreased in muscle from high-fat fed animals, which may partially account for the loss of UnAG’s effects.

Conclusions

UnAG is able to protect muscle from acute lipid exposure, likely due to its ability to stimulation fatty acid oxidation. This effect is lost in high-fat fed animals, implying a resistance to ghrelin at the level of the muscle. The underlying mechanisms accounting for ghrelin resistance in high fat-fed animals remain to be discovered.

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Saturated lipids acutely impair muscle insulin signaling and glucose transport.

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Ghrelin isoforms consistently protect insulin signaling from lipid detriment.

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Unacylated ghrelin more potently stimulates fat oxidation, preserving glucose transport.

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Muscle of chronic high fat-fed rats may be resistant to ghrelin’s metabolic effects.

ASSOCIATION OF GHRELIN RECEPTOR AND INFLAMMATION IN PERI-ATRIAL ADIPOSE TISSUE FROM OBESE PATIENTS WITH POSTOPERATIVE ATRIAL FIBRILLATION

Context

Atrial fibrillation (AF) is the most common sustained arrhythmia in clinical practice. The increasing evidence supports links between inflammation and AF. There is evidence showing that obesity is a major cause of adipose tissue (AT) inflammation. Ghrelin (GHRL), through its growth hormone secretagogue receptor (GHS-R) present on adipose tissue macrophages (ATMs), could modulate AT inflammation.

Objective

Our study aimed to evaluate the role of adipose tissue macrophages (ATMs) and their GHS-R in adipose tissue samples of right atrial appendages (RAA) biopsies.

Subjects and Method

We obtained RAA biopsies from 10 obese patients, undergoing cardiac surgery for coronary artery bypass graft (CABG) and developing postoperative atrial fibrillation (POAF). The epicardial tissue samples were examined using immunohistochemistry to visualize and quantify CD68 and GSH-R expression of the ATMs.

Results

Histologically, the mean adipocyte diameter (MAD) of epicardial adipose tissue (EAT) was larger in EAT samples with inflammation as compared to EAT without inflammation (84.2 µm vs. 79.6 µm). The expression of CD68 was lower in EAT without inflammation as compared to EAT with inflammation in adipose tissue samples. Similarly, the expression of GSH-R was lower in EAT samples without inflammation as compared to EAT samples with inflammation in adipose tissue.

Conclusions

Increased epicardial fat area, macrophage infiltration, and GHS-R expression in epicardial ATMs appeared to be associated with postoperative atrial fibrillation in obese patients.

α-Mangostin remodels visceral adipose tissue inflammation to ameliorate age-related metabolic disorders in mice

Low-grade chronic adipose tissue inflammation contributes to the onset and development of aging-related insulin resistance and type 2 diabetes. In the current study, α-mangostin, a xanthone isolated from mangosteen (Garcinia mangostana), was identified to ameliorate lipopolysaccharides-induced acute adipose tissue inflammation in mice, by reducing the expression of pro-inflammatory cytokines and chemokines. In a cohort of young (3 months) and old (18-20 months) mice, α-mangostin mitigated aging-associated adiposity, hyperlipidemia, and insulin resistance. Further study showed that α-mangostin alleviated aging-related adipose tissue inflammation by reducing macrophage content and shifting pro-inflammatory macrophage polarization. Moreover, α-mangostin protected the old mice against liver injury through suppressing the secretion of microRNA-155-5p from macrophages. The above results demonstrated that α-mangostin represents a new scaffold to alleviate adipose tissue inflammation, which might be a novel candidate to treat aging-related metabolic disorders.

Ghrelin Signaling in Immunometabolism and Inflamm-Aging

Intracellular changes in immune cells lead to metabolic dysfunction, which is termed immunometabolism. Chronic inflammation is a hallmark of aging; this phenomenon is described as inflamm-aging. Immunometabolism and inflamm-aging are closely linked to obesity, insulin resistance, type 2 diabetes (T2D), cardiovascular diseases, and cancers, which consequently reduce life span and health span of the elderly. Ghrelin is an orexigenic hormone that regulates appetite and food intake. Ghrelin's functions are mediated through its receptor, growth hormone secretagogue receptor (GHS-R). Ghrelin and GHS-R have important roles in age-associated obesity, insulin resistance, and T2D. In this chapter, we have discussed the roles of ghrelin signaling in diet-induced obesity and normal aging as it relates to energy metabolism and inflammation in key metabolic tissues and organs. The new findings reveal that ghrelin signaling is an important regulatory mechanism for immunometabolism and inflamm-aging. Ghrelin signaling offers an exciting novel therapeutic strategy for treatment of obesity and insulin resistance of the elderly.

GHS-R1a Deficiency Alleviates Depression-Related Behaviors After Chronic Social Defeat Stress

Ghrelin is an important orexigenic hormone that regulates feeding, metabolism and glucose homeostasis in human and rodents. Ghrelin functions by binding to its receptor, the growth hormone secretagogue receptor 1a (GHS-R1a), which is widely expressed inside and outside of the brain. Recent studies suggested that acyl-ghrelin, the active form of ghrelin, is a persistent biomarker for chronic stress exposure. However, how ghrelin/GHS-R1a signaling contributes to stress responses and mood regulation remains uncertain. In this study, we applied the chronic social defeat stress (CSDS) paradigm to both GHS-R1a knock-out (Ghsr^-/-) mice and littermate control (Ghsr^+/+) mice, and then measured their depression- and anxiety-related behaviors. We found that Ghsr^+/+ mice, but not Ghsr^-/- mice, displayed apparent anxiety and depression after CSDS, while two groups mice showed identical behaviors at baseline, non-stress state. By screening the central and peripheral responses of Ghsr^-/- mice and Ghsr^+/+ mice to chronic stress, we found similar elevations of total ghrelin and adrenocorticotropic hormone (ACTH) in the serum of Ghsr^-/- mice and Ghsr^+/+ mice after CSDS, but decreased interleukin-6 (IL-6) in the serum of defeated Ghsr^-/- mice compared to defeated Ghsr^+/+ mice. We also found increased concentration of brain derived neurotropic factor (BDNF) in the hippocampus of Ghsr^-/- mice compared to Ghsr^+/+ mice after CSDS. The basal levels of ghrelin, ACTH, IL-6, and BDNF were not different between Ghsr^-/- mice and Ghsr^+/+ mice. Our findings thus suggested that the differential expressions of BDNF and IL-6 after CSDS may contribute to less anxiety and less despair observed in GHS-R1a-deficient mice than in WT control mice. Therefore, ghrelin/GHS-R1a signaling may play a pro-anxiety and pro-depression effect in response to chronic stress, while GHS-R1a deficiency may provide resistance to depressive symptoms of CSDS.

Acyl-ghrelin mediated lipid retention and inflammation in obesity-related Type 2 diabetes

Acyl-ghrelin has various peripheral effects including the potential role in mediating cellular lipid removal and macrophage polarization. Previous reports are contradictory as to how glycaemia and acyl-ghrelin mediates lipid retention and inflammation within individuals with Type 2 diabetes (T2D). Our aim was to explore acyl-ghrelin levels and ghrelin expression in relation to lipid and inflammatory markers within an ex vivo human model, biopsied visceral adipose tissue. Results indicated that acyl-ghrelin was associated with a decline in key lipid homeostasis genes ABCG1 and LXRβ expression. Within T2D there was also a down regulation of these genes which was independent of acyl-ghrelin levels. Circulatory pro-inflammatory markers (IL-6 and TNFα) had no association with ghrelin expression nor circulating acyl-ghrelin levels. Anti-inflammatory marker (IL-10) and total antioxidant status (TAOS%) were positively associated with ghrelin expression across samples from all groups combined (total sample cohort) and specifically within the obesity sample cohorts. Data supported the hypothesis that hyperglycaemia and acyl-ghrelin have a regulatory role in lipid retention. Furthermore, that both acyl- and desacyl-ghrelin is responsible for a protective inflammatory response; however this response is diminished in T2D.

aP2-Cre Mediated Ablation of GHS-R Attenuates Adiposity and Improves Insulin Sensitivity during Aging

Ghrelin via its receptor, the growth hormone secretagogue receptor (GHS-R), increases food intake and adiposity. The tissue-specific functions of GHS-R in peripheral tissues are mostly unknown. We previously reported that while GHS-R expression is very low in white and brown fat of young mice, expression increases during aging. To investigate whether GHS-R has cell-autonomous effects in adipose tissues, we generated aP2-Cre-mediated GHS-R knockdown mice (aP2-Cre/Ghsrf/f). We studied young (5⁻6 months) and old (15⁻17 months) aP2-Cre/Ghsrf/f mice and their age-matched controls. Interestingly, young aP2-Cre/Ghsrf/f mice had normal body weight but reduced fat; old mice showed pronounced reductions of both body weight and body fat. Calorimetry analysis revealed that aP2-Cre/Ghsrf/f mice had normal food intake and locomotor activity at both young and old age; but intriguingly, while energy expenditure was normal at young age, it was significantly increased at old age. Both young and old aP2-Cre/Ghsrf/f mice exhibited improved insulin sensitivity and glucose tolerance. Importantly, old aP2-Cre/Ghsrf/f mice maintained higher core body temperature at 4 °C, and showed higher expression of the thermogenic uncoupling protein 1 (UCP1) gene. The ex vivo studies further demonstrated that GHS-R deficient white adipocytes from old mice exhibit increased glucose uptake and lipolysis, promoting lipid mobilization. Despite the fact that the in vivo phenotypes of aP2-Cre/Ghsrf/f mice may not be exclusively determined by GHS-R knockdown in adipose tissues, our data support that GHS-R has cell-autonomous effects in adipocytes. The anabolic effect of GHS-R in adipocytes is more pronounced in aging, which likely contributes to age-associated obesity and insulin resistance.

Ghrelin, a gastrointestinal hormone, regulates energy balance and lipid metabolism

Ghrelin, an acylated peptide hormone of 28 amino acids, is an endogenous ligand of the released growth hormone secretagogue receptor (GHSR). Ghrelin has been isolated from human and rat stomach and is also detected in the hypothalamic arcuate nucleus. Ghrelin receptor is primarily located in the neuropeptide Y and agouti-related protein neurons. Many previous studies have shown that ghrelin and GHSR are involved in the regulation of energy homeostasis, and its administration can increase food intake and body weight gain. AMP-activated protein kinase is activated by ghrelin in the hypothalamus, which contributes to lower intracellular long-chain fatty acid level. Ghrelin appears to modulate the response to food cues via a neural network involved in the regulation of feeding and in the appetitive response to food cues. It also increases the response of brain areas involved in visual processing, attention, and memory to food pictures. Ghrelin is also an important factor linking the central nervous system with peripheral tissues that regulate lipid metabolism. It promotes adiposity by the activation of hypothalamic orexigenic neurons and stimulates the expression of fat storage-related proteins in adipocytes. Meanwhile, ghrelin exerts direct peripheral effects on lipid metabolism, including increase in white adipose tissue mass, stimulation of lipogenesis in the liver, and taste sensitivity modulation.

Assessment of the Aging of the Brown Adipose Tissue by 18F-FDG PET/CT Imaging in the Progeria Mouse Model Lmna-/

Brown adipose tissue (BAT) is an important energy metabolic organ that is highly implicated in obesity, type 2 diabetes, and atherosclerosis. Aging is one of the most important determinants of BAT activity. In this study, we used ¹⁸F-FDG PET/CT imaging to assess BAT aging in Lmna^−/− mice. The maximum standardized uptake value (SUV_Max) of the BAT was measured, and the target/nontarget (T/NT) values of BAT were calculated. The transcription and the protein expression levels of the uncoupling protein 1 (UCP1), beta3-adrenergic receptor (β3-AR), and the PR domain-containing 16 (PRDM16) were measured by quantitative real-time polymerase chain reaction (RT-PCR) and Western blotting or immunohistochemical analysis. Apoptosis and cell senescence rates in the BAT of WT and Lmna^−/− mice were determined by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and by CDKN2A/p16INK4a immunohistochemical staining, respectively. At 14 weeks of age, the BAT SUV_Max and the expression levels of UCP1, β3-AR, and PRDM16 in Lmna^−/− mice were significantly reduced relative to WT mice. At the same time, the number of p16INK4a and TUNEL positively stained cells (%) increased in Lmna^−/− mice. Collectively, our results indicate that the aging characteristics and the aging regulatory mechanism in the BAT of Lmna^−/− mice can mimic the normal BAT aging process.

Improvement of Adipose Macrophage Polarization in High Fat Diet-Induced Obese GHSR Knockout Mice

Purpose

Adipose tissue inflammation is the key linking obesity to insulin resistance. Over 50% of the interstitial cells in adipose tissue are macrophages, which produce inflammatory cytokines and therefore play an important role in the progression of insulin resistance. Within this classification view, macrophage biology is driven by two polarization phenotypes, M₁ (proinflammatory) and M₂ (anti-inflammatory). The unique functional receptor of ghrelin, growth hormone secretagogue receptor (GHSR), is a classic seven-transmembrane G protein-coupled receptor that is linked to multiple intracellular signaling pathways. Knockout of GHSR improves the obesity and glucose metabolic disorders, suggesting a crucial role of ghrelin activity in insulin resistance. Here, we discussed whether macrophage polarization phenotypes in adipose tissue were changed in GHSR knockout (GHSR-/-) mice.

Methods

GHSR-/- mice were fed with normal chow diet (NCD) or high fat diet (HFD). Markers of different macrophage polarization phenotypes were detected by real-time RT-PCR.

Results

The size of adipocytes decreased and interstitial cells, especially infiltrated macrophages, reduced in epididymal adipose tissue of GHSR-/- mice fed with HFD. Compared with wild type mice, the mRNA levels of inflammatory adipokines such as resistin, IL-6, and PAI-1 were significantly lower in epididymal adipose tissue of GHSR-/- mice, whereas anti-inflammatory adipokine, adiponectin, was significantly higher. M₁ markers, MCP-1, TNF-α, and iNOS, were significantly lower in epididymal adipose tissue of GHSR-/- mice, whereas M₂ markers, Arg-1, Mgl-1, were Mrc1, were significantly higher.

Conclusion

The GHSR-/- mice fed with HFD showed suppressed adipose inflammation, reduced macrophage infiltration, and enhanced M₂ polarization of macrophages in adipose tissue, which improved insulin sensitivity.

1,3,6,7-Tetrahydroxy-8-prenylxanthone ameliorates inflammatory responses resulting from the paracrine interaction of adipocytes and macrophages

BACKGROUND AND PURPOSE

Chronic inflammation in adipose tissue is critical in the onset and development of insulin resistance and type 2 diabetes. Macrophage infiltration into adipose tissue and pro-inflammatory polarization play key roles in adipose tissue inflammation. The fruit hull of mangosteen (Garcinia mangostana) is used in traditional medicine to treat various inflammatory diseases. However, its role in regulating adipose tissue inflammation is unexplored. This study was designed to identify xanthones from G. mangostana, which could ameliorate adipose tissue inflammation.

EXPERIMENTAL APPROACH

Expressions of inducible NOS, cytokines, chemokines and components of the NF-κB and MAPKs pathways were evaluated using Western blotting, immunofluorescence, quantitative real-time PCR or ELISA. The migration of macrophages towards adipocytes was tested using Transwell experiments in vitro. A murine model of LPS-induced acute inflammation was used to examine effects of 1,3,6,7-tetrahydroxy-8-prenylxanthone (TPX) on inflammatory responses in adipose tissue in vivo.

KEY RESULTS

From a series of xanthones isolated from G. mangostana, TPX was identified as a potent inhibitor of LPS-induced NO production and IL-6 secretion in RAW264.7 macrophages. TPX ameliorated LPS-induced inflammatory responses in RAW264.7 macrophages, and TNF-α-mediated inflammation in 3T3-L1 adipocytes, through inhibiting MAPKs and NF-κB activation and promoting sirtuin 3 expression. TPX also blocked RAW264.7 macrophages migration towards 3T3-L1 adipocytes in co-cultures. Furthermore, TPX alleviated LPS-induced adipose tissue inflammation in vivo by reducing pro-inflammatory cytokines and preventing the pro-inflammatory polarization of macrophages.

CONCLUSIONS AND IMPLICATIONS

Taken together, our results indicate that TPX disrupts the inflammatory responses between macrophages and adipocytes, and attenuates adipose tissue inflammation.

Ageing potentiates diet-induced glucose intolerance, β-cell failure and tissue inflammation through TLR4

Ageing and obesity are two major risk factors for the development of type 2 diabetes (T2D). A chronic, low-grade, sterile inflammation contributes to insulin resistance and β-cell failure. Toll-like receptor-4 (TLR4) is a major pro-inflammatory pathway; its ligands as well as downstream signals are increased systemically in patients with T2D and at-risk individuals. In the present study we investigated the combined effects of high fat/high sucrose diet (HFD) feeding, ageing and TLR4-deficiency on tissue inflammation, insulin resistance and β-cell failure. In young mice, a short-term HFD resulted in a mildly impaired glucose tolerance and reduced insulin secretion, together with a β-cell mass compensation. In older mice, HFD further deteriorated insulin secretion and induced a significantly impaired glucose tolerance and augmented tissue inflammation in adipose, liver and pancreatic islets, all of which was attenuated by TLR4 deficiency. Our results show that ageing exacerbates HFD-induced impairment of glucose homeostasis and pancreatic β-cell function and survival, and deteriorates HFD-induced induction of mRNA expression of inflammatory cytokines and pro-inflammatory macrophage markers. TLR4-deficiency protects against these combined deleterious effects of a high fat diet and ageing through a reduced expression of inflammatory products in both insulin sensitive tissues and pancreatic islets.

Effect of Bariatric Surgery-Induced Weight Loss on Platelet Count and Mean Platelet Volume: a 12-Month Follow-Up Study

BACKGROUND

Abdominal obesity is strongly correlated with cardiovascular risk and associated with platelet hyperactivity. This hyperactivity is associated with an increase in mean platelet volume (MPV). Few data are available about changes in platelet counts and MPV in obese patients after bariatric surgery (BS). The purpose of this study was to describe quantitative and qualitative changes in the platelet lineage after BS.

METHODS

One hundred twenty-eight consecutive patients were included. The mean age was 43 ± 12 years, 77 % of patients were female, and the mean preoperative BMI was 44 ± 6 kg/m². Ninety patients (71 %) had a Roux-en-Y gastric bypass (RYGBP), and 38 (29 %) had a sleeve gastrectomy (SG). Patients were evaluated preoperatively, and postoperative follow-up was performed at 3, 6, and 12 months. The postoperative evaluation included blood samples for full blood count (FBC), including measure of mean platelet volume (MPV).

RESULTS

At the 12-month follow-up, the reduction in preoperative weight was 29 ± 9 %. We showed a significant decrease in platelet count (245 ± 62 vs. 234 ± 54 G/L; p = 0.0015) found in parallel with a non-significant decrease in MPV (9.27 ± 1.1 vs. 9.22 ± 1.05; p = 0.34). With regard to the intervention type, SG caused a more significant decrease in platelet count than RYGBP (p = 0.02). There was no significant difference in MPV variations between the two groups (p = 0.08).

CONCLUSIONS

Our results suggest that BS has a positive impact on platelet metabolism, possibly mediated by weight loss. These data need to be confirmed to understand the multifactorial benefits of BS on cardiovascular risk in obese patients.