Glucose-dependent insulinotropic polypeptide (GIP) is secreted by enteroendocrine K cells, primarily located in the upper small intestine, in response to food intake and plays a significant role in the postprandial regulation of nutrient metabolism. Although the importance of GIP in metabolic regulation has long been recognized, progress in developing GIP as a therapeutic target has been limited. However, the GIP/GIP receptor (GIPR) axis has garnered increasing attention in recent years. Emerging evidence suggests that dual GIP/GLP-1 receptor agonists and triple GIP/GLP-1/glucagon receptor agonists provide beneficial metabolic effects in individuals with type 2 diabetes and obesity. In this review, we outline the physiological roles of GIP, detailing the mechanisms of GIP secretion from K cells in response to macronutrients, its actions on key target organs involved in metabolic regulation, and ongoing developments in its therapeutic applications.

Childhood obesity is a growing global health concern, contributing to numerous non-communicable diseases and long-term health complications. The prevalence of obesity in children and adolescents continues to rise, driven by complex interactions among various factors. The key risk factors include both environmental and genetic influences. Environmental factors include family elements like household conditions and lifestyle, while genetic factors refer to inherited predispositions. More recently, epigenetic factors have gained attention, focusing on chemical modifications such as DNA methylation that are influenced by the prenatal and early-life environment and may contribute to obesity risk. Unlike obesity in adults, the risk factors for obesity in children are largely dependent on their family environments rather than individual behaviors. For effective intervention, it is important to identify at-risk children and their families as early as possible after birth. Despite advances in machine learning, polygenic risk scores, and epigenomic markers—which show promise as being more accurate and comprehensive prediction methods—no risk prediction models are currently in clinical use. Achieving predictions with higher accuracy, external validation, and consideration of population-specific factors (e.g., ethnic variability) while avoiding bias or stigma in targeted interventions is needed for effective childhood obesity prevention. Herein, we summarize environmental, genetic, and epigenetic risk factors for childhood obesity and review the unique situations and regional factors in Japan, which are the focus of our study. Furthermore, we introduce the major advances in risk prediction models for childhood obesity.

The 2017 World Health Organization classification described aggressive pituitary neuroendocrine tumor (PitNET) as “a tumor with strong invasiveness and rapid growth, which is difficult to treat with surgery, radiation therapy, or drug therapy,” which remains a challenge in the treatment of pituitary tumors. Currently, temozolomide (TMZ) is the first-line treatment for aggressive PitNET. However, it is not yet covered by insurance in Japan. Additionally, O6-Methylguanine-DNA Methyltransferase (MGMT) expression can lead to treatment resistance, further complicating treatment selection. We previously demonstrated the effectiveness of combination therapy with capecitabine (CAPTEM) in several cases of aggressive PitNETs. The present study described our experiences with TMZ in 13 patients with aggressive PitNETs (including four patients administered CAPTEM). Pathological examination revealed eight corticotroph, four lactotroph, and one somatotroph tumors. Of these, seven patients are still receiving treatment, and six patients have terminated treatment. The reasons for discontinuation were poor efficacy (three patients), financial reasons (two patients), and patient preference (one patient). No patients required treatment discontinuation owing to adverse events. Furthermore, one case of a lactotroph tumor, which achieved remission with CAPTEM but was discontinued after three years for financial reasons, remains in remission on imaging and maintained normal PRL levels for 15 months after discontinuation. The most significant issue is off-label use. Concern exists that financial constraints may prevent future patients from using TMZ.

Children with idiopathic short stature (ISS) and growth hormone deficiency (GHD) exhibit imbalances in gut microbiota (GM), and the latter is related to endocrine hormones (such as insulin-like growth factor 1 (IGF-1)). The current study investigated the compositional and functional variations in GM between children with ISS and GHD, employing 16S rRNA sequencing technology. Sequencing results from 15 children with ISS and 18 children with GHD indicated no significant differences in GM alpha diversity or phylum-level diversity between the ISS and GHD groups. At the genus level, the abundance of Terrisporobacter was significantly greater in the ISS group compared to the GHD group, whereas the abundance of Acidovorax was reduced. The abundance of Prevotella stercorea and uncultured Sutterella sp. at the species level was significantly lower in the ISS group compared to the GHD group. The third level (L3) of the Kyoto Encyclopedia of Genes and Genomes (KEGG) database revealed functional variations in GM, with children in the ISS group having higher levels of intestinal bacteria Mobility Proteins and Background Chemotaxis. Despite these differences, the overall composition and function of GM between ISS and GHD children were not significantly different, indicating that the mechanisms by which GM influences the growth and development of children in both groups may be similar. This study was registered with the Medical Research Registration and Record System with the registration number MR-44-24-045472.

Some cases of obesity are thought to be associated with hypo-leptinemia. This may cause decreased appetite suppression resulting in increased appetite, leading to weight gain. Replacement therapy with leptin might be theoretically useful, but verification by reporting more cases is required. Here, we first investigated the serum leptin levels and their correlation with body mass index (BMI) in 107 patients with obesity to identify the subjects with hypo-leptinemia. Among them, one patient with congenital hypopituitarism was further investigated by comparison of his clinical and pathological characteristics with those of control subjects. This 40-year-old Japanese man, who was large from birth, consistently showed obesity of more than 2SD during his growth period. He had 41.5 kg/m² at BMI with central hypogonadism, central diabetes insipidus and severe growth hormone deficiency, cognitive impairment, and abnormal eating behavior, which led to suspicion of the involvement of hypothalamic factors. Genetic analysis revealed no definite mutations regarding metabolic and nutritional systems or adipocytes including leptin-related genes. Electron microscopic images of subcutaneous adipose tissue demonstrated relatively smaller adipocytes compared with a BMI-matched patient. The patient suffered from his abnormal eating behavior, began dialysis at the age of 41 years, and died of bacterial pneumonia at 49 years of age. Among patients with severe obesity with hypo-leptinemia, there could be patients with disturbance of healthy expansion in adipocyte, probably due to unknown dysfunction. Even with the lack of abnormality of leptin-related genes, indication of leptin-replacement may be considered for severely obese patients with hypo-leptinemia.

No evidence-based standards exist regarding levothyroxine (LT4) replacement therapy initiation timing in patients with hyperthyroid Graves’ disease undergoing total thyroidectomy. Although LT4 replacement from the first postoperative day has been the standard of care at our hospital, its clinical validity has not been thoroughly examined. This study investigated the perioperative kinetics of thyroid hormones to assess the safety and efficacy of early LT4 initiation. Thirty patients with Graves’ disease (18 hyperthyroid and 12 euthyroid) and 12 with thyroid nodules who underwent total thyroidectomy were included. Blood samples were collected from each patient for thyroid hormone measurement on the day before surgery (D-1), 15 min after surgery (D0), at 8:00 am on days 1 (D1) and 3 (D3), and 3 weeks (W3) and 3 months (M3) after surgery. In 18 patients with hyperthyroid Graves’ disease, serum free triiodothyronine (FT3) levels significantly decreased immediately after surgery and were within the normal range by D1. Although LT4 was started on D1, FT3 levels continued to decline by D3 and remained low at W3 and M3. Serum FT4 levels followed a slower decline but remained within the normal range for M3. In patients with euthyroid Graves’ disease and those with thyroid nodules, hormone levels stayed within or around the reference range throughout the observation period. In conclusion, initiating LT4 on the day after surgery is safe and effective for maintaining thyroid function in patients with hyperthyroid Graves’ disease undergoing total thyroidectomy. These results could inform future guidelines, supporting earlier postoperative LT4 initiation.

Pregnant women with Graves’ disease (GD) who have undergone thyroidectomy or radioactive iodine therapy can have high levels of thyroid-stimulating hormone (TSH) receptor antibodies, which are transferred to the fetus via the placenta, posing a risk for fetal GD. This retrospective observational study, conducted at two high-level perinatal medical centers in Tokyo and Osaka, Japan, aimed to identify predictors of fetal GD in pregnant women with GD who had undergone thyroidectomy or radioactive iodine therapy. In total, 65 women were included, and 79 singleton pregnancies and fetuses were analyzed. Fetal GD occurred in 17.7% of the 79 fetuses. Women in the fetal GD group had higher levels of TSH receptor antibodies and a higher prevalence of ophthalmopathies than did women in the non-fetal GD group. The receiver operating characteristic curve cutoff values of maternal TSH-binding inhibitory immunoglobulin (hereafter referred to as TRAb [TSH receptor antibody from a narrow perspective]) and thyroid-stimulating antibody (TSAb) levels predictive of fetal GD development were as follows: TRAb, 12.8 and 10.2 IU/L at 10 and 20 gestational weeks (GW), respectively; TSAb, 975.4% and 1,259.0% at 10 and 20 GW, respectively. Ophthalmopathy was a predictor of fetal GD; nonetheless, combining the ophthalmopathy and TRAb cutoff values did not improve predictive accuracy. A cutoff value of TRAb ≥10.2 IU/L at 20 GW (highest diagnostic accuracy found) could be a predictor of fetal GD risk for pregnant women with GD who undergo thyroidectomy or radioactive iodine therapy; thus, appropriate fetal monitoring should begin at around 20 GW.

The prevalence of metabolic syndrome (MS) is rising due to lifestyle changes. To investigate the pathogenesis of MS and identify potential biomarkers, bioinformatics tools were used to screen for MS-related genes, such as Fras-1-related extracellular matrix protein 2 (FREM2), and miRNAs, including miR-28-5p and miR-424-5p. An insulin resistance (IR) cell model was established by treating human liver cells with insulin. The roles of FREM2, miR-28-5p, and miR-424-5p in IR were examined through overexpression and silencing experiments. Transfection of miR-28-5p/miR-424-5p mimics and a dual-luciferase assay were performed to explore their regulation of FREM2. The diagnostic value of miR-28-5p/miR-424-5p in MS was assessed using the receiver operating characteristic (ROC) curve. Increased expression of FREM2 and suppression of miR-28-5p/miR-424-5p enhanced glucose uptake in IR cells. Transfection with miR-28-5p or miR-424-5p mimics reduced luciferase activity in cells transfected with the wild-type FREM2 reporter vector and suppressed FREM2 expression. The ROC curve analysis indicated that miR-28-5p and miR-424-5p serve as effective classifiers for MS, with their combined use offering higher reliability. In conclusion, miR-28-5p and miR-424-5p exacerbated IR progression in human liver cells (HHL-5) through the negative regulation of FREM2, and they are potential biomarkers for MS.

Multiple endocrine neoplasia type 2B (MEN2B) is a rare autosomal dominant disorder caused by germline pathogenic RET variants. On the other hand, Charcot–Marie–Tooth disease (CMT) is a hereditary neurological disorder, characterized by distal muscle weakness and sensory loss, with approximately 100 identified causative genes. Herein, we report a de novo RET mutation in a patient presenting with clinical features of both MEN2B and CMT. The patient, a 22-year-old woman, had a history of lower limb muscle weakness, with no family history of MEN2B or CMT. The patient was being treated for a thyroid gland neoplasm. Genetic testing of the medullary thyroid carcinoma revealed a previously unreported RET germline variant, p.M918W (RET: c.2752_2753delinsTG, p.Met918Trp). The novel p.M918W RET variant was associated with concurrent MEN2B and CMT. This finding was unexpected as MEN2B typically manifests with distinct features, such as marfanoid habitus and mucosal neuromas, but not with muscle weakness, as seen in CMT. Based on this finding, the plausible role of the p.M918W mutation as a shared pathway for both MEN2B and CMT warrants further investigation.