Mitochondrial glutathione peroxidase 4 is indispensable for photoreceptor development and survival in mice.

Glutathione peroxidase 4 (GPx4) is known for its unique function in the direct detoxification of lipid peroxides in the cell membrane and as a key regulator of ferroptosis, a form of lipid peroxidation-induced nonapoptotic cell death. However, the cytosolic isoform of GPx4 is considered to play a major role in inhibiting ferroptosis in somatic cells, whereas the roles of the mitochondrial isoform of GPx4 (mGPx4) in cell survival are not yet clear. In the present study, we found that mGPx4 KO mice exhibit a cone-rod dystrophy-like phenotype in which loss of cone photoreceptors precedes loss of rod photoreceptors. Specifically, in mGPx4 KO mice, cone photoreceptors disappeared prior to their maturation, whereas rod photoreceptors persisted through maturation but gradually degenerated afterward. Mechanistically, we demonstrated that vitamin E supplementation significantly ameliorated photoreceptor loss in these mice. Furthermore, LC-MS showed a significant increase in peroxidized phosphatidylethanolamine esterified with docosahexaenoic acid in the retina of mGPx4 KO mice. We also observed shrunken and uniformly condensed nuclei as well as caspase-3 activation in mGPx4 KO photoreceptors, suggesting that apoptosis was prevalent. Taken together, our findings indicate that mGPx4 is essential for the maturation of cone photoreceptors but not for the maturation of rod photoreceptors, although it is still critical for the survival of rod photoreceptors after maturation. In conclusion, we reveal novel functions of mGPx4 in supporting development and survival of photoreceptors in vivo.

[A Case of Pancreas Neuroendocrine Carcinoma Achieved Long-Term Survival by Carboplatin plus Etoposide Therapy].

A 70-year-old man with the history of diabetes mellitus complained of lower abdominal discomfort. Abdominal ultrasonography revealed a pancreatic mass. Contrast enhanced CT showed a 2.6 cm-enhanced tumor ventral to the pancreatic head. It was diagnosed with a pancreatic neuroendocrine carcinoma(PanNEC-G3)by EUS-FNA. The patient underwent pancreatoduodenectomy with the wedge resection of the portal vein and partial resection of the transverse colon. We administered 6 cycles of adjuvant therapy with CDDP plus CPT-11. With the presentation of lymph node metastases and the local recurrence in the anastomotic site of the transverse colon 15 months after surgery, the patient received carboplatin plus etoposide(CE)therapy. Although local recurrence completely responded to the CE therapy, bone metastases were detected 27 months after surgery. Metastatic lesion did not respond to systemic chemotherapy including gemcitabine plus nab-paclitaxel and nal-IRI plus 5-FU/LV, and the patient eventually died 37 months after the surgery. PanNECs represent for less than 1% of all pancreatic tumor. They are characterized by high malignant potential and short time survival with the reported OS of 8.5 to 21 months. This case served as an important reminder to consider multimodal treatment for PanNEC patients to obtain longer survival.

Dietary ω3 fatty acid exerts anti-allergic effect through the conversion to 17,18-epoxyeicosatetraenoic acid in the gut.

ω3 polyunsaturated fatty acids (PUFAs) have anti-allergic and anti-inflammatory properties, but the immune-metabolic progression from dietary oil remains to be investigated. Here we identified 17,18-epoxyeicostetraenoic acid (17,18-EpETE) as an anti-allergic metabolite generated in the gut from dietary ω3 α-linolenic acid (ALA). Biochemical and imaging mass spectrometry analyses revealed increased ALA and its metabolites, especially eicosapentaenoic acid (EPA), in the intestines of mice receiving ALA-rich linseed oil (Lin-mice). In murine food allergy model, the decreased incidence of allergic diarrhea in Lin-mice was due to impairment of mast cell degranulation without affecting allergen-specific serum IgE. Liquid chromatography-tandem mass spectrometry-based mediator lipidomics identified 17,18-EpETE as a major ω3 EPA-derived metabolite generated from dietary ALA in the gut, and 17,18-EpETE exhibits anti-allergic function when administered in vivo. These findings suggest that metabolizing dietary ω3 PUFAs generates 17,18-EpETE, which is an endogenous anti-allergic metabolite and potentially is a therapeutic target to control intestinal allergies.

Immunomodulation with eicosapentaenoic acid supports the treatment of autoimmune small-vessel vasculitis.

Small-vessel vasculitis is a life-threatening autoimmune disease that is frequently associated with anti-neutrophil cytoplasmic antibodies (ANCAs). Conventional immunotherapy including steroids and cyclophosphamide can cause serious adverse events, limiting the efficacy and safety of treatment. Eicosapentaenoic acid (EPA), a key component of fish oil, is an omega-3 polyunsaturated fatty acid widely known to be cardioprotective and beneficial for vascular function. We report two elderly patients with systemic ANCA-associated vasculitis (AAV) in whom the administration of EPA in concert with steroids safely induced and maintained remission, without the use of additioal immunosuppressants. To explore the mechanisms by which EPA enhances the treatment of AAV, we employed SCG/Kj mice as a spontaneous murine model of AAV. Dietary enrichment with EPA significantly delayed the onset of crescentic glomerulonephritis and prolonged the overall survival. EPA-derived anti-inflammatory lipid mediators and their precursors were present in the kidney, plasma, spleen, and lungs in the EPA-treated mice. Furthermore, a decrease in ANCA production and CD4/CD8-double negative T cells, and an increase in Foxp3(+) regulatory T cells in the lymph nodes of the kidney were observed in the EPA-treated mice. These clinical and experimental observations suggest that EPA can safely support and augment conventional therapy for treating autoimmune small-vessel vasculitis.

Omega-3 fatty acids protect renal functions by increasing docosahexaenoic acid-derived metabolite levels in SHR.Cg-Lepr(cp)/NDmcr rats, a metabolic syndrome model.

The omega-3 polyunsaturated fatty acids (ω-3 PUFAs) docosahexaenoic acid (DHA) and/or eicosapentaenoic acid (EPA) protect against diabetic nephropathy by inhibiting inflammation. The aim of this study was to assess the effects of highly purified DHA and EPA or EPA only administration on renal function and renal eicosanoid and docosanoid levels in an animal model of metabolic syndrome, SHR.Cg-Lepr(cp)/NDmcr (SHRcp) rats. Male SHRcp rats were divided into 3 groups. Control (5% arabic gum), TAK-085 (300 mg/kg/day, containing 467 mg/g EPA and 365 mg/g DHA), or EPA (300 mg/kg/day) was orally administered for 20 weeks. The urinary albumin to creatinine ratio in the TAK-085-administered group was significantly lower than that in other groups. The glomerular sclerosis score in the TAK-085-administered group was significantly lower than that in the other groups. Although DHA levels were increased in total kidney fatty acids, the levels of nonesterified DHA were not significantly different among the 3 groups, whereas the levels of protectin D1, resolvin D1, and resolvin D2 were significantly increased in the TAK-085-administered group. The results show that the use of combination therapy with DHA and EPA in SHRcp rats improved or prevented renal failure associate with metabolic syndrome with decreasing triglyceride levels and increasing ω-3 PUFA lipid mediators.

Increased tissue levels of omega-3 polyunsaturated fatty acids prevents pathological preterm birth.

Omega-3 polyunsaturated fatty acids such as eicosapentaenoic acid (EPA) have anti-inflammatory effects. Preterm birth is an important problem in modern obstetrics and one of the main causes is an inflammation. We here showed that abundance of omega-3 fatty acids reduced the incidence of preterm birth induced by LPS with fat-1 mice, capable of converting omega-6 to omega-3 fatty acids. We also indicated that the gene expression of IL-6 and IL-1ß in uteruses and the number of cervical infiltrating macrophages were reduced in fat-1 mice. The analyses of lipid metabolomics showed the high level of 18-hydroxyeicosapentaenoate in fat-1 mice, which was derived from EPA and was metabolized to anti-inflammatory product named resolvin E3 (RvE3). We finally showed that the administration of RvE3 to LPS-exposed pregnant wild type mice lowered the incidence of preterm birth. Our data suggest that RvE3 could be a potential new therapeutic for the prevention of preterm birth.

Omega-3 polyunsaturated Fatty acids suppress the cystic lesion formation of peritoneal endometriosis in transgenic mouse models.

Omega-3 polyunsaturated fatty acids (omega-3 PUFAs) play a role in controlling pathological inflammatory reactions. Endometriosis is characterized by the presence of endometrial tissue on the peritoneum and an exaggerated inflammatory environment around ectopic tissues. Here peritoneal endometriosis was reproduced using a mouse model in which murine endometrial fragments were inoculated into the peritoneal cavity of mice. Fat-1 mice, in which omega-6 can be converted to omega-3 PUFAs, or wild type mice, in which it cannot, were used for the endometriosis model to address the actions of omega-3 PUFAs on the development of endometriotic lesions. The number and weight of cystic endometriotic lesions in fat-1 mice two weeks after inoculation were significantly less than half to those of controls. Mediator lipidomics revealed that cystic endometriotic lesions and peritoneal fluids were abundant in 12/15-hydroxyeicosapentaenoic acid (12/15-HEPE), derived from eicosapentaenoic acid (EPA), and their amount in fat-1 mice was significantly larger than that in controls. 12/15-Lipoxygenase (12/15-LOX)-knockout (KO) and control mice with or without EPA administration were assessed for the endometriosis model. EPA administration decreased the number of lesions in controls but not in 12/15-LOX-KO mice. The peritoneal fluids in EPA-fed 12/15-LOX-KO mice contained reduced levels of EPA metabolites such as 12/15-HEPE and EPA-derived resolvin E3 even after EPA administration. cDNA microarrays of endometriotic lesions revealed that Interleukin-6 (IL-6) expression in fat-1 mice was significantly lower than that in controls. These results suggest that both endogenous and exogenous EPA-derived PUFAs protect against the development of endometriosis through their anti-inflammatory effects and, in particular, the 12/15-LOX-pathway products of EPA may be key mediators to suppress endometriosis.

Stereochemical assignment and anti-inflammatory properties of the omega-3 lipid mediator resolvin E3.

Uncontrolled inflammation is now considered to be a link between many widely occurring diseases. Thus, controlling the innate inflammatory response and its local chemical mediators has been receiving increasing attention. We recently identified a novel family of eicosapentaenoic acid (EPA)-derived mediators produced by eosinophils, denoted as resolvin E3 (RvE3), that possess potent anti-inflammatory actions both in vitro and in vivo. Carbons at 17 and 18 positions are asymmetric and thus the molecule has a total of four potential stereoisomers. Here, we assigned the stereochemistry of the conjugated double bonds and chirality of alcohols present in two natural isomers of RvE3 with four different stereoisomers prepared by total organic synthesis. The complete structures of two natural isomers of RvE3 were determined to be 17R,18S- and 17R,18R-dihydroxy-5Z,8Z,11Z,13E,15E-EPA, respectively. These natural isomers prepared by total organic synthesis displayed a potent anti-inflammatory action by limiting neutrophil infiltrations both in vitro and in vivo. The unnatural stereoisomers were much less active compared with the natural isomers, demonstrating the stereoselective action of RvE3.