砂河 孝行

The ring finger protein 213 (RNF213) gene, identified in 2011 as a susceptibility gene for moyamoya disease (MMD), has since been recognized as a key factor in a broader spectrum of vascular disorders. The p.R4810K mutation in RNF213 is particularly common among Japanese MMD patients, although a smaller percentage of healthy individuals also carry the mutation, indicating that environmental factors, alongside genetic predisposition, likely influence disease onset. RNF213, a large E3 ubiquitin ligase, plays essential roles in vascular homeostasis, immune response, and endoplasmic reticulum stress reaction. Its mutation disrupts normal angiogenesis, contributing to abnormal vascular remodeling in conditions such as pulmonary hypertension and coronary artery disease. This review examines the multifaceted role of RNF213 and its p.R4810K mutation in the pathogenesis of MMD and other vascular conditions, collectively referred to as RNF213-associated vascular diseases. While research has begun to clarify the mutation's effects on angiogenesis and the involved pathways, the roles of RNF213 and its mutation in vascular integrity remain unclear. This comprehensive overview underscores the complex interaction between genetic and environmental factors in RNF213-related vascular diseases and calls for further research to elucidate these mechanisms and develop targeted therapeutic interventions.

Fibrosis is the ultimate outcome of various chronic diseases that affect multiple organs, including the liver, lungs, heart, and kidneys. This pathological process is characterized by the excessive accumulation of extracellular matrix produced by activated myofibroblasts in response to chronic injury, as part of a degenerative process of dysregulated tissue repair. While numerous pathways have been implicated in the development of fibrosis, the precise mechanisms that drive and exacerbate organ fibrosis remain inconclusive. Consequently, there are currently very limited treatments for organ fibrosis. In recent years, immune cells have been identified as critical mediators of the fibrotic cascade, capable of inducing tissue damage or promoting repair. Harnessing immune cells and immunotherapeutic approaches to intervene in the fibrotic process is a promising avenue towards new treatment options. In this review, we explore the pathophysiology of fibrosis in various organs, with a specific focus on the role of immune cells in both the development and regression of fibrosis as well as the latest preclinical findings with relation to immunotherapeutic treatment approaches. Understanding the role of immune responses in fibrotic diseases will aid in the development of immunotherapeutic strategies that target key pro-fibrotic cytokines and immune cells, with the aim of preventing fibrosis or promoting its regression.

Mesothelial and epicardial cells give rise to various types of mesenchymal cells via epithelial (mesothelial)-to-mesenchymal transition during development. However, the genes controlling the differentiation and diversification of mesothelial/epicardial cells remain unclear. Here, we examined Wnt2b expression in the embryonic mesothelium and epicardium and performed lineage tracing of Wnt2b-expressing cells by using novel Wnt2b-2A-CreERT2 knock-in and LacZ-reporter mice. Wnt2b was expressed in mesothelial cells covering visceral organs, but the expression was restricted in their subpopulations. Wnt2b-expressing cells labeled at embryonic day (E) 10.5 were distributed to the mesothelium and mesenchyme in the lungs, abdominal wall, stomach, and spleen in Wnt2b2A-CreERT2/+;R26RLacZ/+ mice at E13.0. Wnt2b was initially expressed in the proepicardial organ (PEO) at E9.5 and then in the epicardium after E10.0. Wnt2b-expressing PEO cells labeled at E9.5 differentiated into a small fraction of cardiac fibroblasts and preferentially localized at the left side of the postnatal heart. LacZ+ epicardium-derived cells labeled at E10.5 differentiated into a small fraction of fibroblasts and smooth muscle cells in the postnatal heart. Taken together, our results reveal novel subpopulations of PEO and mesothelial/epicardial cells that are distinguishable by Wnt2b expression and elucidate the unique contribution of Wnt2b-expressing PEO and epicardial cells to the postnatal heart.