Aim/hypothesis Mitochondria and the endoplasmic reticulum (ER) physically interact by close structural juxtaposition, via the mitochondria-associated ER membrane. Inter-organelle communication between the ER and mitochondria has been shown to regulate energy metabolism and to be central to the modulation of various key processes such as ER stress. We aimed to clarify the role of mitochondrial fission in this communication.Methods We generated mice lacking the mitochondrial fission protein dynamin-related protein 1 (DRP1) in the liver (Drp1LiKO mice). Results Drp1LiKO mice showed decreased fat mass and were protected from high-fat diet (HFD)-induced obesity. Analysis of liver gene expression profiles demonstrated marked elevation of ER stress markers. In addition, we observed increased expression of the fibroblast growth factor 21 (FGF21) gene through induction of activating transcription factor 4, master regulator of the integrated stress response. Conclusions/interpretation Disruption of mitochondrial fission in the liver provoked ER stress, while inducing the expression of FGF21 to increase energy expenditure and protect against HFD-induced obesity.

BackgroundNivolumab, an anti-programmed cell death-1 monoclonal antibody, has improved the survival of patients with malignant melanoma. Despite its efficacy, nivolumab inconsistently induces thyroid dysfunction as an immune-related adverse event (irAE). This study aimed to evaluate nivolumab-induced thyroid dysfunction to determine the risks and mechanisms of thyroid irAEs.MethodsAfter excluding 10 patients, data of 24 patients with malignant melanoma (aged 17–85 years; 54% female) were retrospectively analyzed.ResultsThyroid irAEs were observed in seven patients (29%). Three patients had hypothyroidism after preceding transient thyrotoxicosis, and the other four patients had hypothyroidism without thyrotoxicosis. Levothyroxine-Na replacement was required in three patients. Antithyroid antibody (ATA) titer was elevated in one of four assessable patients. The average (±SD) time to onset of thyroid irAE was 33.6 (±21.9) weeks. The administration period of nivolumab was longer in patients with thyroid irAEs than in those without thyroid irAEs (P < 0.01). There were no significant differences between patients with and without thyroid irAEs regarding age, sex, tumor stage, response to nivolumab therapy, baseline thyroid function, antithyroid peroxidase antibody (anti-TPO Ab) and antithyroglobulin antibody (anti-Tg Ab).ConclusionsThyroid dysfunction was a common irAE of nivolumab in malignant melanoma. Neither anti-TPO Ab nor anti-Tg Ab was associated with the risk for nivolumab-induced thyroid dysfunction. A conventional ATA-independent mechanism might be involved in thyroid irAEs. Further studies are required to clarify the mechanism and identify the predictive factors of thyroid irAEs.

Introduction: Malignant struma ovarii is a rare neoplasm. It is usually asymptomatic and not commonly diagnosed preoperatively. In addition, there is currently no established diagnostic and therapeutic approach for malignant struma ovarii. Case Report: A 66-year-old asymptomatic female was referred to our hospital. Computed tomography showed the presence of a well-defined mass with enhancement in the internal and peripheral areas. The patient underwent total abdominal hysterectomy, bilateral salpingo-oophorectomy, and partial omentectomy. Histopathology revealed the presence of a papillary thyroid carcinoma arising from a 2.5-cm-diameter struma ovarii (malignant struma ovarii). According to the criteria of the International Federation of Gynecology and Obstetrics, the patient had stage IA disease. Subsequently, she underwent a thyroid scan with normal findings. At the 3-month follow-up, the patient was alive, in good clinical condition, and disease free. Conclusion: In this report, we present the smallest malignant struma ovarii reported so far in the literature. Because of the rarity of these tumors and the lack of firm prognostic factors, the treatment decision should be customized for each patient according to the pathological and clinical parameters.