Public Library Science Acta Medica Okayama 1932-6203 17 11 2022 Cysteinyl leukotriene receptor 1 is dispensable for osteoclast differentiation and bone resorption e0277307 EN Hirofumi Fujita Department of Cytology and Histology, Okayama University Faculty of Medicine, Dentistry and Pharmaceutical Sciences Aoi Ando Faculty of Medicine, Okayama University Medical School Yohei Mizusawa Faculty of Medicine, Okayama University Medical School Mitsuaki Ono Department of Molecular Biology and Biochemistry, Okayama University Faculty of Medicine, Dentistry and Pharmaceutical Sciences Takako Hattori Department of Biochemistry and Molecular Dentistry, Okayama University Faculty of Medicine, Dentistry and Pharmaceutical Sciences Munenori Habuta Department of Cytology and Histology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Toshitaka Oohashi Department of Molecular Biology and Biochemistry, Okayama University Faculty of Medicine, Dentistry and Pharmaceutical Sciences Satoshi Kubota Department of Biochemistry and Molecular Dentistry, Okayama University Faculty of Medicine, Dentistry and Pharmaceutical Sciences Hideyo Ohuchi Department of Cytology and Histology, Okayama University Faculty of Medicine, Dentistry and Pharmaceutical Sciences Cysteinyl leukotriene receptor 1 (CysLTR1) is a G protein-coupled receptor for the inflammatory lipid mediators cysteinyl leukotrienes, which are involved in smooth muscle constriction, vascular permeability, and macrophage chemokine release. The Cysltr1 gene encoding CysLTR1 is expressed in the macrophage lineage, including osteoclasts, and the CysLTR1 antagonist Montelukast has been shown to suppress the formation of osteoclasts. However, it currently remains unclear whether CysLTR1 is involved in osteoclast differentiation and bone loss. Therefore, to clarify the role of CysLTR1 in osteoclastogenesis and pathological bone loss, we herein generated CysLTR1 loss-of-function mutant mice by disrupting the cysltr1 gene using the CRISPR-Cas9 system. These mutant mice had a frameshift mutation resulting in a premature stop codon (Cysltr1 KO) or an in-frame mutation causing the deletion of the first extracellular loop (Cysltr1(Delta 105)). Bone marrow macrophages (BMM) from these mutant mice lost the intracellular flux of calcium in response to leukotriene D-4, indicating that these mutants completely lost the activity of CysLTR1 without triggering genetic compensation. However, disruption of the Cysltr1 gene did not suppress the formation of osteoclasts from BMM in vitro. We also demonstrated that the CysLTR1 antagonist Montelukast suppressed the formation of osteoclasts without functional CysLTR1. On the other hand, disruption of the Cysltr1 gene partially suppressed the formation of osteoclasts stimulated by leukotriene D-4 and did not inhibit that by glutathione, functioning as a substrate in the synthesis of cysteinyl leukotrienes. Disruption of the Cysltr1 gene did not affect ovariectomy-induced osteoporosis or lipopolysaccharide-induced bone resorption. Collectively, these results suggest that the CysLT-CysLTR1 axis is dispensable for osteoclast differentiation in vitro and pathological bone loss, while the leukotriene D-4-CysTR1 axis is sufficient to stimulate osteoclast formation. We concluded that the effects of glutathione and Montelukast on osteoclast formation were independent of CysLTR1. No potential conflict of interest relevant to this article was reported.

Public Library Science Acta Medica Okayama 1932-6203 17 11 2022 Left atrial appendage morphology with the progression of atrial fibrillation e0278172 EN Yoichi Takaya Department of Cardiovascular Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Rie Nakayama Department of Cardiovascular Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Fumi Yokohama Department of Cardiovascular Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Norihisa Toh Department of Cardiovascular Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Koji Nakagawa Department of Cardiovascular Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Masakazu Miyamoto Department of Cardiovascular Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Hiroshi Ito Department of Cardiovascular Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Left atrial appendage (LAA) size is crucial for determining the indication of transcatheter LAA closure. The aim of this study was to evaluate the differences in LAA morphology according to the types of atrial fibrillation (AF). A total of 299 patients (mean age: 67 +/- 13 years) who underwent transesophageal echocardiography (TEE) were included. Patients were classified into non-AF (n = 64), paroxysmal AF (n = 86), persistent AF (n = 87), or long-standing persistent AF (n = 62). LAA morphology, including LAA ostial diameter and depth, was assessed using TEE. Patients with long-standing persistent AF had larger LAA ostial diameter and depth and lower LAA flow velocity. The maximum LAA ostial diameter was 19 +/- 4 mm in patients with non-AF, 21 +/- 4 mm in patients with paroxysmal AF, 23 +/- 5 mm in patients with persistent AF, and 26 +/- 5 mm in patients with long-standing persistent AF. LAA ostial diameter was increased by 2 or 3 mm with the progression of AF. LAA ostial diameter was correlated with LA volume index (R = 0.37, P < 0.01) and the duration of continuous AF (R = 0.30, P < 0.01), but not with age or the period from the onset of AF. In conclusion, LAA size was increased with the progression of AF. No potential conflict of interest relevant to this article was reported.