👤 Akiyoshi Hirayama

Western diet (WD) fed Melanocortin 4 receptor-knockout (MC4R-KO) mice develop a phenotype resembling human metabolic dysfunction-associated steatohepatitis (MASH). Despite its clinical relevance, the role of the gut–liver axis in MASH pathogenesis remains unclear. We investigated the gut-liver axis through microbiomic and metabolomic analyses of WD-fed MC4R-KO mice, and we examined their association with MASH pathology. We performed an integrated microbiome and metabolome analysis of the liver, small intestinal contents, large intestinal contents, and plasma of wild-type (WT) and MC4R-KO mice fed either a normal diet or WD. Markers of hepatic inflammation, fibrosis, and steatosis measured in this study were used to assess MASH severity and to correlate microbiome and metabolite alterations. WD-fed MC4R-KO mice exhibited significant hepatic steatosis, inflammation, and fibrosis. The abundance of certain microbiota, including Muribaculaceae and The observed gut microbial and metabolic alterations, particularly bile acid and lipid metabolism dysregulation, offer insights into potential therapeutic targets aimed at modulating the gut–liver axis to treat or prevent MASH. The online version contains supplementary material available at 10.1186/s13099-026-00813-9. Show less

Arrhythmogenic cardiomyopathy (ACM) is an inherited cardiac disorder characterized by progressive fibrofatty replacement of the myocardium. In the Japanese population, variants of the desmoglein-2 ( A 6-year-old asymptomatic girl was diagnosed with ACM based on abnormal electrocardiogram findings, including epsilon waves, and T-wave inversions in leads V This case illustrates the potential for severe pediatric ACM associated with compound heterozygous This case underscores the genetic heterogeneity and phenotypic variability in inherited cardiomyopathies. It emphasizes the importance of comprehensive genetic testing and close monitoring of affected individuals and their families. Show less

Dual-specificity phosphatase 6 (DUSP6) is a specific phosphatase for mitogen-activated protein kinase (MAPK). This study used a high-fat diet (HFD)-induced murine nonalcoholic fatty liver disease model to investigate the role of DUSP6 in this disease. Wild-type (WT) and Dusp6-haploinsufficiency mice developed severe obesity and liver pathology consistent with nonalcoholic fatty liver disease when exposed to HFD. In contrast, Dusp6-knockout (KO) mice completely eliminated these phenotypes. Furthermore, primary hepatocytes isolated from WT mice exposed to palmitic and oleic acids exhibited abundant intracellular lipid accumulation, whereas hepatocytes from Dusp6-KO mice showed minimal lipid accumulation. Transcriptome analysis revealed significant down-regulation of genes encoding cytochrome P450 4A (CYP4A), known to promote ω-hydroxylation of fatty acids and hepatic steatosis, in Dusp6-KO hepatocytes compared with that in WT hepatocytes. Diminished CYP4A expression was observed in the liver of Dusp6-KO mice compared with WT and Dusp6-haploinsufficiency mice. Knockdown of DUSP6 in HepG2, a human liver-lineage cell line, also promoted a reduction of lipid accumulation, down-regulation of CYP4A, and up-regulation of phosphorylated/activated MAPK. Furthermore, inhibition of MAPK activity promoted lipid accumulation in DUSP6-knockdown HepG2 cells without affecting CYP4A expression, indicating that CYP4A expression is independent of MAPK activation. These findings highlight the significant role of DUSP6 in HFD-induced steatohepatitis through two distinct pathways involving CYP4A and MAPK. Show less

Psoriasis is an immune-mediated dermatosis usually associated with comorbidities. Treatment varies from topicals to systemic drugs and data on susceptibility to viral infections in psoriatic patients are scarce. The objectives of this study were to analyze psoriatic patients on different therapies who were at risk for COVID-19 for seroprevalence of SARS-COV-2, pro-inflammatory cytokine profile, comorbidities and outcomes in order to unveil the immunological mechanisms involved in the anti-viral response in patients with psoriasis. Seventy-five patients with psoriasis were divided according to treatment: immunobiologics, methotrexate, topicals and acitretin. Twenty healthy controls were included. Plasma samples were collected for: IgG SARS-COV-2 (ELISA); IL-27, IL-29 and IL-18 (ELISA); and IL-1β, IL-17A, IL-6 and TNF (cytometric array). Seropositivity for SARS-COV-2 was detected in 24 out of 75 psoriasis patients and did not relate to COVID-19 symptoms and/or hospitalization, despite associated comorbidities. Psoriasis patients who were asymptomatic for SARS-COV-2 exhibited immune imbalance with high levels of IL-18, IL-17A and IL-6, and low levels of IL-27 compared to healthy controls. Psoriasis groups showed significant increased cytokine levels only in the group with immunobiologics. Despite immune deviations and lower IL-27, which has a potential antiviral impact, psoriatic patients did not exhibit complications related to COVID-19. An understanding of this kind of proinflammatory profile of psoriatic patients and of the lack of severe outcomes for COVID-19 is essential to establish novel therapeutic approaches and preventive measures, including with regard to the concomitance of viral infections. Show less

Few data exist as to whether dipeptidyl peptidase (DPP)-4 inhibitors affect cardio-renal interaction, which is a strong independent prognostic factor for cardiovascular disease (CVD), in diabetic patients. We evaluated the effects of a DPP-4 inhibitor on atherogenic low-density lipoprotein (LDL) heterogeneity and albuminuria in diabetics as an indicator of the severity of diabetic nephropathy. Type 2 diabetes patients (n = 47) inadequately controlled with diabetes therapy were treated with vildagliptin 50 mg bid for 8 weeks. LDL heterogeneity was evaluated on the basis of the patients' small dense (sd) LDL levels and sd-LDL proportion (sd-LDL/LDL cholesterol [LDL-C]). The level of albuminuria was evaluated on the basis of the urinary albumin-to-creatinine ratio (UACR). After 8 weeks of treatment, there was no significant change in serum LDL-C level, but the serum sd-LDL level had decreased significantly by 8.8 %, and the UACR had also decreased significantly by 44.6 %. Triglyceride (TG)-metabolism-related markers (TG, remnant-like particle cholesterol, apolipoprotein [apo] B, apoC-2, and apoC-3) had decreased significantly. The Δ (absolute change from baseline) sd-LDL values correlated positively with ΔTG-metabolism-related markers, but not with the Δ hemoglobin (Hb) A1c or Δ fasting blood sugar (ΔFBS). Furthermore, multivariate regression analysis revealed that Δsd-LDL proportion, but not ΔHbA1c or ΔFBS, was an independent predictor of ΔUACR (β = 0.292, p = 0.0016). Although this was a single-arm study, treatment of type 2 diabetes with vildagliptin might prevent the progression of CVD complicating diabetes by improving LDL heterogeneity, and it might improve renal function by decreasing albuminuria. A randomized controlled trial is warranted. Show less

Calcineurin is an important mediator that connects the Ca(2+)-dependent signaling to various cellular responses in a wide variety of cell types and organisms. In budding yeast, activated calcineurin exerts its function mainly by regulating the Crz1p/Tcn1 transcription factor. Here, we cloned the fission yeast prz1(+) gene, which encodes a zinc finger transcription factor highly homologous to Crz1/Tcn1. Similar to the results in budding yeast, calcineurin dephosphorylated Prz1 and resulted in the trans-location of Prz1 from the cytoplasm to the nucleus. Prz1 expression was stimulated by high extracellular Ca(2+) in a calcineurin-dependent fashion. However, unlike in budding yeast, the prz1-null cells did not show any phenotype similar to those previously reported in calcineurin deletion such as aberrant cell morphology, mating defect, or hypersensitivity to Cl(-). Instead, the prz1-null cells showed hypersensitivity to Ca(2+), consistent with a dramatic decrease in transcription of Pmc1 Ca(2+) pump. Interestingly, overexpression of Prz1 did not suppress the Cl(-) hypersensitivity of calcineurin deletion, and overexpression of Pmp1 MAPK phosphatase suppressed the Cl(-) hypersensitivity of calcineurin deletion but not the Ca(2+) hypersensitivity of prz1 deletion. In addition, mutations in the its2(+)/cps1(+), its8(+), and its10(+)/cdc7(+) genes that showed synthetic lethal genetic interaction with calcineurin deletion did not exhibit synthetic lethality with the prz1 deletion. Our results suggest that calcineurin activates at least two distinct signaling branches, i.e. the Prz1-dependent transcriptional regulation and an unknown mechanism, which functions antagonistically with the Pmk1 MAPK pathway. Show less