Human milk-specific fat components enhance the secretion of ghrelin by MGN3-1 cells.

Triacylglycerols (TAGs) are a major fat component in human milk. Since gastric lipase produces 1,2-diacylglycerol from TAGs, we focused on the bioactivity of human milk-derived diacylglycerols in stomach cells. Ghrelin is produced in the stomach and acts as an important regulator of growth hormone secretion and energy homeostasis. In this study, we showed that 1-oleoyl-2-palmitoylglycerol (OP) increased ghrelin secretion, whereas 1,3-dioleoyl-2-palmitoylglycerol (OPO), a major component of human milk TAGs, did not increase ghrelin secretion in the ghrelin-secreting cell line, MGN3-1. Therefore, diacylglycerol OP may directly contribute to the regulation of ghrelin secretion. We also found that 2-palmitoylglycerol and 1- and 2-oleoylglycerol increased ghrelin secretion. Finally, we demonstrated that intracellular cAMP levels and preproghrelin and ghrelin O-acyl transferase expression levels were enhanced by OP treatment in MGN3-1 cells. This may represent an example of a novel mother-infant interaction mediated by fat components derived from human breast milk.

Thyroid function, glycemic control, and diabetic nephropathy in patients with type 2 diabetes over 24 months: prospective observational study.

BACKGROUND: The higher prevalence of thyroid dysfunction in type 1 diabetes patients has been well established, whereas it is a matter of debate whether that is also observed in type 2 diabetes patients. This study was conducted to reveal whether higher prevalence of thyroid dysfunction is observed in patients with type 2 diabetes. METHODS: We examined thyroid functions and thyroid autoantibodies in 200 patients with type 2 diabetes and 225 controls, with 24 months follow up for those with type 2 diabetes. RESULTS: Serum free triiodothyronine (fT3) levels and fT3/free thyroxine (fT4) ratio were significantly lower, while fT4 levels were significantly higher in patients with type 2 diabetes. The number of patients with thyroid dysfunction or patients positive for thyroid autoantibodies were not different between the two groups. The fT3/fT4 ratio was positively and negatively correlated with serum c-peptide and HbA1c levels, respectively, suggesting that the difference can be attributable to insulin resistance and diabetic control. In the follow-up observation, we found no significant correlation between basal thyrotropin (TSH), fT3, fT4 or fT3/fT4 ratio with the amounts of changes of HbA1c levels at 12 or 24 months after the basal measurements. There was a negative relationship between TSH levels and eGFR at baseline measurements, but TSH levels did not seem to predict future decline of eGFR levels. No relationship was observed between urine albumin/ g‧cre levels and thyroid function. CONCLUSION: Thyroid dysfunction and thyroid autoantibodies were not different in prevalence between patients with type 2 diabetes and controls, although in patients with type 2 diabetes, the fT3/fT4 ratio was decreased. Basal thyroid function did not predict future diabetes control or renal function within 24 months of follow-up.

Isolated ACTH deficiency following immunization with the BNT162b2 SARS-CoV-2 vaccine: a case report.

BACKGROUND: The global COVID-19 pandemic requires urgent development of new vaccines. Endocrinological adverse effects following the new mRNA vaccine against COVID-19 have been reported in several cases. Specific to the involvement of pituitary function; however, only a single case with hypophysis has been reported. This is the first case of isolated adrenocorticotropic hormone (ACTH) deficiency (IAD) following mRNA vaccination against COVID-19. CASE PRESENTATION: A healthy 31-year-old man received the BNT162b2 SARS-CoV-2 mRNA vaccine. The first injection was uneventful. One day after the second injection, he noticed general fatigue and fever. In the following several days, he additionally developed headaches, nausea, and diarrhea. Four days after the vaccine injection, he visited a hospital with worsening of these symptoms. Physical examination revealed slight disorientation but no other deficits. Laboratory tests revealed hyponatremia, hypoglycemia, and extremely low plasma ACTH and serum cortisol levels (ACTH < 1.5 pg/ml, cortisol 1.6 µg/dl). He was diagnosed with adrenal crisis and was emergently treated with hydrocortisone. The symptoms responded well and he recovered within a few days. Magnetic resonance images after the replacement with hydrocortisone revealed an atrophic pituitary gland. The patient was referred to our tertiary hospital for further endocrinological examination. Pituitary endocrine load tests revealed isolated adrenocortical response deficiency. After other clinical assessments, he was diagnosed as having isolated ACTH deficiency. After initiation of hydrocortisone replacement, there has been no recurrence of symptoms related to adrenocortical insufficiency nor involvement of other pituitary functions. CONCLUSION: This is the first reported case of IAD potentially associated with COVID-19 immunization. Recent reports have emphasized the importance of adjuvants in the mRNA vaccine that induce the endocrinological adverse effects through disturbance of the autoimmune system, but details are still unclear. Given the broad and rapid spread of vaccinations against COVID-19, it is clinically important to consider that there could be cases with a rare but emergent adrenal crisis even among those who present common symptoms of adverse effects following inactive SARS-CoV-2 mRNA vaccination.

Hypopituitarism and cranial nerve involvement mimicking Tolosa-Hunt syndrome as the initially presenting feature of diffuse large B-cell lymphoma: a case report.

BACKGROUND: Early diagnosis of lymphoma involving the central nervous system is sometimes difficult but emergent to avoid the delay of therapeutic initiation. Pituitary insufficiencies are usually associated with lymphoma in the pituitary gland. There have been no cases of lymphoma originating from extra pituitary gland with hypopituitarism that simultaneously presenting unilateral upper cranial nerve palsies and ophthalmalgia. These symptoms are mostly caused by neoplastic involvement of the skull base or benign diseases such as Tolosa-Hunt syndrome (THS). We report a case of lymphoma with unique clinical courses initially presenting hypopituitarism and symptoms mimicking THS with a mass in sphenoidal and cavernous sinuses accompanying sphenoidal bone erosion. CASE PRESENTATION: A 71-year-old woman visited our hospital with left ophthalmalgia, ptosis, and diplopia. Neurological findings revealed left oculomotor, trochlear and abducent nerve palsies. Endocrine tests indicated partial hypopituitarism. Initial CT and MRI revealed that a mass in sphenoidal and cavernous sinuses had invaded the sella with osteolysis of the sphenoid bone. At around four weeks, almost all the symptoms of cranial nerve palsies were relieved. Seven weeks later, she had a high fever and cervical lymph node (CLN) swellings. CLN biopsy revealed CD20-positive B-cells. She was diagnosed with diffuse large B-cell lymphoma (DLBCL). 18F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) revealed elevated uptake at the erosion lesion of the sphenoidal bone, but not the pituitary gland. After chemotherapy, all the symptoms related to systemic lymphoma were relieved, but partial hypopituitarism remained. The mass in sphenoidal and cavernous sinuses and elevated uptake by PET/CT were dissolved. CONCLUSION: This case of DLBCL had a unique clinical course; initial presentation of hypopituitarism and symptoms mimicking THS. There was also rare demonstration of mass lesions related to DLBCL in the sphenoidal and cavernous sinuses compressing the pituitary gland through an eroded area of the sphenoidal bone. It should be clinically cautioned that DLBCL can be associated with erosion of the sphenoidal bone and cause both hypopituitarism and THS-mimicking symptoms.

Laparoscopic sleeve gastrectomy for morbid obesity improves gut microbiota balance, increases colonic mucosal-associated invariant T cells and decreases circulating regulatory T cells.

BACKGROUND: Laparoscopic sleeve gastrectomy (LSG) for morbid obesity may improve gut microbiota balance and decrease chronic inflammation. This study examines the changes in gut microbiota and immune environment, including mucosal-associated invariant T cells (MAIT cells) and regulatory T cells (Treg cells) caused by LSG. METHODS: Ten morbidly obese patients underwent LSG at our institution between December 2018 and March 2020. Flow cytometry for Th1/Th2/Th17 cells, Treg cells and MAIT cells in peripheral blood and colonic mucosa and 16S rRNA analysis of gut microbiota were performed preoperatively and then 12 months postoperatively. RESULTS: Twelve months after LSG, the median percent total weight loss was 30.3% and the median percent excess weight loss was 66.9%. According to laboratory data, adiponectin increased, leptin decreased, and chronic inflammation improved after LSG. In the gut microbiota, Bacteroidetes and Fusobacteria increased after LSG, and indices of alpha diversity increased after LSG. In colonic mucosa, the frequency of MAIT cells increased after LSG. In peripheral blood, the frequency of Th1 cells and effector Treg cells decreased after LSG. CONCLUSIONS: After LSG for morbid obesity, improvement in chronic inflammation in obesity is suggested by change in the constituent bacterial species, increase in the diversity of gut microbiota, increase in MAIT cells in the colonic mucosa, and decrease in effector Treg cells in the peripheral blood.

Distinct clinical features and prognosis between persistent and temporary thyroid dysfunctions by immune-checkpoint inhibitors.

Immune-related adverse events in the thyroid glands (thyroid irAEs) during treatment with immune-checkpoint inhibitors (ICIs) are most frequent endocrine irAE. Thyroid irAE can be divided into that requiring continuous therapy for thyroid dysfunction (P-THY), and that requiring only temporal treatment (T-THY). However, predictive factors for those differential outcomes are unknown, and susceptibility of human leukocyte antigen (HLA) to thyroid irAE has never been investigated. This study aimed to elucidate clinical courses and prognosis of P-THY in comparison with T-THY in the aspect of thyroid immunity and HLA. Patients with P-THY (n = 15) that required L-T4 supplemental therapy for hypothyroidism for more than 3 months, and patients with T-THY who required no therapy or therapy within 1 month were enrolled in the study. Lower-value of TSH, higher-value of FT4, and lower value of TSH/FT4 were thought to be predictive markers to estimate P-THY. In addition, anti-thyroglobulin antibody (TgAb) levels were significantly higher in patients with P-THY than those in patients with T-THY. HLA-DPA1*01:03 and HLA-DPB1*02:01 allele, and their haplotype frequencies were significantly higher in patients with P-THY than those in controls. P-THY had better survival rate than T-THY. Pre-existing thyroid autoimmunity, the extent of thyroid dysfunction, and predisposing HLA were associated with the differential course of thyroid irAEs. It was suggested that thyroid function tests, TgAb, and HLA typing tests are useful for prediction of clinical course in thyroid irAEs.

Predictive and sensitive biomarkers for thyroid dysfunctions during treatment with immune-checkpoint inhibitors.

Immune-related adverse events (irAEs) are often seen during immune-checkpoint inhibitor (ICI) treatment of various malignancies. Endocrine irAEs including thyroid dysfunctions are the most common irAEs, but their biomarkers remain unclear. In order to identify individuals who are susceptible to thyroid irAE for earlier diagnosis and appropriate follow-up, the current study is aimed to investigate biomarkers of thyroid irAE. Herein, patients with advanced malignant diseases who received ICIs treatment were prospectively studied. Clinical and laboratory examination, thyroid function, and autoantibodies were evaluated at baseline, and every 4 wk after first treatment with ICIs. Cytokines/chemokines were measured at baseline and at 4 wk. In vivo effects of ICIs on experimental autoimmune thyroiditis were evaluated. Twenty-six patients with malignant diseases who received ICIs treatment were enrolled in the study. Patients were divided into two groups: those who developed thyroid irAE, and those without irAEs. Comparing the two groups, early increase (≤4 wk) in serum thyroglobulin (Tg) levels and thyroid autoantibodies was seen in thyroid irAE (P < .05). Notably, higher levels of serum IL-1ß, IL-2, and GM-CSF at baseline, and early decrease of IL-8, G-CSF, and MCP-1 were significantly associated in the development of thyroid irAE (P < .05). In vivo effects of anti-PD-1 antibody on deterioration of mice experimental thyroiditis were seen. In conclusion, early change in Tg, thyroid autoimmunity, and cytokine levels might indicate development of thyroid irAE. Pre-existing thyroid autoimmunity might be involved with the development of thyroid irAE. Potential application of these factors as surrogate biomarkers for tumor therapy was indicated.

Autoimmune polyglandular syndrome type 2 and autoimmune hepatitis with thymoma-associated myasthenia gravis: case report.

BACKGROUND: Autoimmune polyglandular syndrome type 2 (APS-2) is a rare and complex clinical entity, and little is known about its etiology and progression. CASE PRESENTATION: A 52-year-old woman with autoimmune hepatitis (AIH) and bronchial asthma was diagnosed with APS-2; autoimmune Addison's disease (AD), and Hashimoto's thyroiditis (HT), and she underwent prednisolone (PSL) treatment. Five months later, she presented ptosis and was diagnosed with thymoma-associated myasthenia gravis (MG). Thymectomy and PSL treatment with immuno-suppressants appeared to ameliorate MG, AD, AIH, HT, and bronchial asthma. HLA typing analysis revealed that the patient had susceptible HLA alleles to MG, AIH, and HT in a Japanese population. CONCLUSIONS: This case suggests common endocrinological and autoimmune aspects of APS-2 and AIH with thymoma-associated MG, which are considered to be extremely rare complications.

Expression of unfolded protein response markers in the pheochromocytoma with Waardenburg syndrome: a case report.

BACKGROUND: It is clinically emergent to further understand the pathological mechanism to advance therapeutic strategy for endocrine tumors. A high amount of secretory protein with tumorigenic triggers are thought to induce unfolded protein response in endoplasmic reticulum in endocrine tumors, but its evidence is limited. CASE PRESENTATION: A 40-year-old woman had an approximately 10-year history of intermittent headaches. After the incidental detection of a mass in her right adrenal gland by CT scan, she was admitted to our hospital. She had been diagnosed as type 1 Waardenburg syndrome with the symptoms of dystopia canthorum, blue iris, and left sensorineural hearing loss. Urinary catecholamine levels were markedly elevated. 123I-MIBG scintigraphy showed uptake in the mass in her adrenal gland. After the adrenalectomy, her headaches disappeared and urinary catecholamine levels decreased to normal range within 2 weeks. Genome sequencing revealed germline mutation of c.A175T (p.Ile59Phe) in transcription factor PAX3 gene and somatic novel mutation of c.1893_1898del (p. Asp631_Leu633delinsGlu) in proto-oncogene RET in her pheochromocytoma. RNA expression levels of RET were increased 139 times in her pheochromocytoma compared with her normal adrenal gland. Those of unfolded protein response markers, Bip/GRP78, CHOP, ATF4, and ATF6, were also increased in the pheochromocytoma. CONCLUSION: We report a rare case of pheochromocytoma with type 1 Waardenburg syndrome. This is the first case to show the activation of unfolded protein response in the pheochromocytoma with the novel somatic mutation in RET gene. Our findings may support that unfolded protein response is activated in endocrine tumors, which potentially could be a candidate of therapeutic target.

The influence of thyroid autoimmunity on pregnancy outcome in infertile women: a prospective study.

Thyroid dysfunction and thyroid autoimmunity (TAI) have been reported to be linked to infertility, pregnancy loss and preterm birth. Infertile women undergoing assisted reproductive technology are recommended to maintain thyroid stimulating hormone (TSH) levels below 2.5 µIU/mL. It is unclear, however, whether levothyroxine (L-T4) treatment decreases the effects of TAI on fertility and pregnancy outcome in infertile women. We therefore aimed to clarify the influence of TAI on pregnancy undergoing L-T4 treatment for hypothyroidism. Prospectively recruited to this study were the 595 infertile women who visited the Utsunomiya Ladies Clinic between January 2013 and December 2015. Five patients with Graves' disease were excluded. Clinical profiles of 590 women were as follows: proportion of SCH = 19.6%, thyroid peroxidase antibody (TPOAb) positivity = 10.4%, and thyroglobulin antibody (TgAb) positivity = 15.1%. Fertility was not affected by any thyroid-associated factors. Regarding pregnancy outcomes, TPOAb titers were significantly higher in women who had miscarriage than in those progressed to delivery (46.4 ± 114.1 vs. 18.9 ± 54.6 IU/mL, p = 0.039), notably in those undergoing intrauterine insemination (p = 0.046) and in vitro fertilization (p = 0.023). Multivariate logistic regression analysis revealed that higher age (odds ratio 26.4, p < 0.001) and higher TPOAb titer (odds ratio 11.8, p = 0.043) were risk factors for miscarriage. Higher TPOAb titer should be considered as one of the risk factors for miscarriage in infertile women, even if they have been treated with L-T4 for hypothyroidism.

False-positive staining of thyroglobulin distinguished from mixed medullary and follicular thyroid carcinoma by duplex in situ hybridization.

Medullary thyroid carcinoma (MTC) may mimic mixed medullary and follicular thyroid carcinoma (MMFTC). MTC originates from para-follicular cells, while MMFTC is an uncommon tumor characterized by coexistence of follicular and para-follicular cell-derived tumor populations. A 35-year-old woman was diagnosed with MTC but showed a hot nodule in thyroid scintigraphy. The tumor included diffusely-spread follicular lesions within it, which were immunostained with thyroglobulin and calcitonin. Immunofluorescence showed the presence of several tumor cells that were double-stained with thyroglobulin and calcitonin. To clarify whether or not the tumor was MMFTC, we used duplex in situ hybridization (ISH). Thyroglobulin and calcitonin-related polypeptide alpha mRNA were not expressed together in a single cell, so we suspected false-positive staining of tumor cells with thyroglobulin. To make comparisons with other follicular lesions in MTC, we searched our hospital database. Five cases within a ten-year period had been pathologically diagnosed as MTC. All had follicular lesions in the tumor, but unlike the other case, they were peripherally localized. Dual differentiation into follicular or para-follicular tumor cells was not indicated by either immunofluorescence or duplex ISH. Compared with the case suspected to be MMFTC, there was only mild invasion of tumor cells into the follicular epithelium. The extent of follicular lesions and invasiveness of tumor cells may be associated with pseudo-staining of thyroglobulin in MTC. Duplex ISH can distinguish MTC that are stained with thyroglobulin from MMFTC.

Comparative analysis of human leucocyte antigen between idiopathic and anti-PD-1 antibody induced isolated adrenocorticotropic hormone deficiency: A pilot study.

BACKGROUND: Adult-onset idiopathic isolated adrenocorticotropic hormone deficiency (id-IAD) is a rare disease with unknown aetiology. Recently, numerous cases of anti-PD-1 antibody-induced IAD (PD1-IAD) have been reported, but the clinical course, predictive factors and relationship to id-IAD have not been clarified. Moreover, associations of id-IAD and PD1-IAD with human leucocyte antigen (HLA) require elucidation. METHODS: Clinical characteristics of 13 Japanese patients with id-IAD and eight Japanese patients with PD1-IAD were analysed, and HLA-typing test was performed for each patient. Allele and haplotype frequencies of the patients were compared to those of healthy Japanese controls. RESULTS: In the HLA allele and haplotype analyses of id-IAD, the frequencies of HLA-C*14:02, HLA-DPB1*05:01, HLA-DRB1*04:05-DQB1*04:01-DPB1*05:01 and HLA-DRB1*09:01-DQB1*03:03-DPB1*05:01 were significantly increased. On the other hand, HLA alleles account for PD1-IAD susceptibility as follows: HLA-DQB1*06:01, HLA-DPB1*09:01 and HLA-DRB5*01:02. Moreover, protective effect for HLA-C*03:03 was suggested in combined id-IAD and PD1-IAD patients. Comparison of the effects of HLA on id-IAD and PD1-IAD revealed some differences. Alleles or haplotypes frequencies increased in id-IAD group were as follows: HLA-DPB1*05:01, HLA-DRB1*09:01, HLA-DRB4*01:03:02, HLA-DQB1*03:03 and HLA-DRB1*09:01-DQB1*03:03. In clinical settings, hyponatremia, disturbance of consciousness and hypoglycaemia were less frequently seen in patients with PD1-IAD than in patients with id-IAD. CONCLUSIONS: Distinct clinical characteristics and predisposing HLA allele contributions were proposed between id-IAD and PD1-IAD. Further investigations with greater number of cases are warranted to clarify the detailed mechanisms of id-IAD and PD1-IAD.

Comprehensive research on thyroid diseases associated with autoimmunity: autoimmune thyroid diseases, thyroid diseases during immune-checkpoint inhibitors therapy, and immunoglobulin-G4-associated thyroid diseases.

Various thyroid diseases are associated with autoimmunity. Major autoimmune thyroid diseases are Graves' disease (GD) and Hashimoto's thyroiditis (HT). Thyrotropin receptor is an autoantigen in GD, and its immunogenicity has been examined. Immune-checkpoint inhibitor (ICI) is recently widely used for treatment of malignant tumors, but cases of thyroid diseases during ICI treatment have been increasing. Thyroid diseases during ICI therapy have been investigated in immunological and clinical aspects, and their Japanese official diagnostic guidelines were established. In addition, serum and tissue immunoglobulin-G4 levels have been examined in association with clinicopathological characteristics in GD, HT, and Riedel's thyroiditis. We review these diseases associated with thyroid autoimmunity and comprehensively discuss their potential application in future research and therapeutic options.

CRISPR/Cas9-mediated Angptl8 knockout suppresses plasma triglyceride concentrations and adiposity in rats.

Angiopoietin-like protein (ANGPTL)8 is a liver- and adipocyte-derived protein that controls plasma triglyceride (TG) levels. Most animal studies have used mouse models. Here, we generated an Angptl8 KO rat model using a clustered regulatory interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 (Cas9) (CRISPR/Cas9) system to clarify the roles of ANGPTL8 in glucose and lipid metabolism. Compared with WT rats, Angptl8 KO rats had lower body weight and fat content, associated with impaired lipogenesis in adipocytes; no differences existed between the groups in food intake or rectal temperature. Plasma TG levels in both the fasted and refed states were significantly lower in KO than in WT rats, and an oral fat tolerance test showed decreased plasma TG excursion in Angptl8 KO rats. Higher levels of lipase activity in the heart and greater expression of genes related to ß-oxidation in heart and skeletal muscle were observed in Angptl8 KO rats. However, there were no significant differences between KO and WT rats in glucose metabolism or the histology of pancreatic ß-cells on both standard and high-fat diets. In conclusion, we demonstrated that Angptl8 KO in rats resulted in lower body weight and plasma TG levels without affecting glucose metabolism. ANGPTL8 might be an important therapeutic target for obesity and dyslipidemia.

[Endocrine Organ Dysfunction with Immune-Checkpoint Inhibitors].

Cytotoxic T-lymphocyte associated antigen 4(CTLA-4), programmed death 1(PD-1), and programmed death-ligand 1 (PD-L1)are referred to as immune-checkpoints. CTLA-4 is located on the surface of activated T-cells, therefore inhibiting binding of CD28 to B7 molecule on antigen presenting cells. The CTLA-4 pathway predominantly acts in lymph nodes. PD-1 is majorly expressed on T-cells. The PD-1 pathway is involved with tumor microenvironment. Immune-checkpoint inhibitors (ICIs)are monoclonal antibodies to these molecules and are promising novel agents for malignant tumor treatment. ICIs promote T-cell-mediated cytotoxicity directed at cancer cell antigens. Approximately 20-30% of patients with advanced cancer were found to be responders of ICIs. However, various adverse events have been reported as immune-related adverse events(irAEs). IrAEs include dermatological, gastrointestinal, hepatic, neurological, and endocrine disorders. In the endocrine system, irAEs in the pituitary glands, thyroid glands, pancreas, and adrenal glands have been reported. Since rapidly progressive fatal endocrine systems failure may provoke during ICI therapy, precise diagnosis and prompt treatment as well as close follow-up is critical. We propose routine monitoring of endocrine functions and related symptoms(ie. worsened fatigue, hyperglycemia, hypoglycemia, hypotension, and hyponatremia), as well as other laboratory tests during ICI therapy. We herein discuss possible mechanisms of endocrine irAEs with ICIs, and highlight diagnostic approaches, treatments, and future prospects of endocrine irAEs during ICI therapy.

Endogenous peptide profile for elucidating biosynthetic processing of the ghrelin precursor.

Ghrelin is an orexigenic peptide primarily produced by gastric endocrine cells. The biosynthetic cleavage site of ghrelin has been well documented, but how its downstream region undergoes proteolytic processing remains poorly explored. Here, we provide the first snapshot of endogenous peptides from the ghrelin precursor by profiling the secretopeptidome of cultured mouse ghrelin-producing cells during exocytosis. Mapping of MS/MS sequenced peptides to the precursor highlighted three atypical monobasic processing sites, including the established C-terminus of ghrelin and the N-terminal cleavage site for obestatin, a putative 23-amino-acid C-terminally amidated peptide. However, we found that mouse obestatin does not occur in the form originally reported, but that a different amidation site is used to generate a shorter peptide. These data can be extended to study and characterize the precursor-derived peptides located downstream of ghrelin in different biological contexts.

The effects of inflammatory cytokines on the expression of ghrelin.

In the current study, we examined the effects of LPS and inflammatory cytokines including IL-1ß, TNF-α, and IL-6 on the expression of ghrelin in MGN3-1 cells. We found that IL-1ß, and TNF-α with lesser extent, significantly suppressed ghrelin mRNA expression in the cells. MGN3-1 cells expressed IL-1ß receptor and IL-1ß significantly stimulated NF-κB, p38, JNK, and ERK pathways. Knockdown of IKK2 by siRNA significantly attenuated the suppression of ghrelin mRNA by IL-1ß. These results indicate that IL-1ß directly suppressed ghrelin mRNA via NF-κB pathway at least partially, which may have a role in the regulation of appetite during inflammation.

The regulation of circulating ghrelin - with recent updates from cell-based assays.

Ghrelin is a stomach-derived orexigenic hormone with a wide range of physiological functions. Elucidation of the regulation of the circulating ghrelin level would lead to a better understanding of appetite control in body energy homeostasis. Earlier studies revealed that circulating ghrelin levels are under the control of both acute and chronic energy status: at the acute scale, ghrelin levels are increased by fasting and decreased by feeding, whereas at the chronic scale, they are high in obese subjects and low in lean subjects. Subsequent studies revealed that nutrients, hormones, or neural activities can influence circulating ghrelin levels in vivo. Recently developed in vitro assay systems for ghrelin secretion can assess whether and how individual factors affect ghrelin secretion from cells. In this review, on the basis of numerous human, animal, and cell-based studies, we summarize current knowledge on the regulation of circulating ghrelin levels and enumerate the factors that influence ghrelin levels.

Reduction in circulating ghrelin concentration after maturation does not affect food intake.

Ghrelin has a potent orexigenic effect and induces adiposity when administered exogenously. Since plasma ghrelin levels rise before meals, ghrelin was thought to play a crucial role in the regulation of appetite. In contrast, mice deficient in the production of ghrelin or the corresponding receptor, GHS-R, do not eat less, throwing the role of ghrelin in the regulation of energy homeostasis into question. Since these mice lack ghrelin or GHS-R from the time of conception, the possibility that compensatory mechanisms may have arisen during development cannot be ruled out. In this study, we used a transgenic mouse model that expresses human diphtheria toxin (DT) receptor cDNA under the control of the ghrelin promoter (GPDTR-Tg mice). As previously reported, an injection of DT into this mouse model ablates ghrelin-secreting cells in the stomach but not in the hypothalamus, resulting in a reduction in circulating ghrelin levels. We used this model system to evaluate the physiological roles of circulating ghrelin in the regulation of food intake. Meal patterns, diurnal and nocturnal meal sizes, and cumulative food intake of DT-treated GPDTR-Tg mice were not affected, although circulating ghrelin levels markedly decreased even after fasting. These mice also displayed normal responses to starvation; however, the use of fat increased and slower weight gain when maintained on a high fat diet was observed. Together, these data suggest that circulating ghrelin does not play a crucial role in feeding behavior, but rather is involved in maintaining body weight.

Clinical effects of ghrelin on gastrointestinal involvement in patients with systemic sclerosis.

The majority of patients with systemic sclerosis (SSc) have gastrointestinal (GI) tract involvement, but therapies using prokinetic agents are usually unsatisfactory. Ghrelin stimulates gastric motility in healthy human volunteers. In this study, we investigated whether ghrelin could improve gastric emptying in patients with gastrointestinal symptoms due to SSc. The study was performed in a randomized, double-blind, placebo-controlled crossover fashion on two occasions. Ten SSc patients with GI tract involvement received an infusion of either ghrelin (5.0 µg/kg) or saline, and gastric emptying rate was evaluated by ¹³C-acetic acid breath test. Gastric emptying was significantly accelerated by ghrelin infusion in patients with SSc (ghrelin vs. saline: 43.3 ± 11.4 min vs. 53.4 ± 5.4 min, P=0.03). No serious adverse effects were observed. Our results suggest that ghrelin might represent a new therapeutic approach for GI tract involvement in patients with SSc.