Calcium-Sensing Receptor Regulates Cytosolic [Ca 2+ ] and Plays a Major Role in the Development of Pulmonary Hypertension.

Pulmonary arterial hypertension (PAH) is a progressive disease characterized by elevated pulmonary vascular resistance (PVR) leading to right heart failure and premature death. The increased PVR results in part from pulmonary vascular remodeling and sustained pulmonary vasoconstriction. Excessive pulmonary vascular remodeling stems from increased pulmonary arterial smooth muscle cell (PASMC) proliferation and decreased PASMC apoptosis. A rise in cytosolic free Ca2+ concentration ([Ca2+]cyt) in PASMC is a major trigger for pulmonary vasoconstriction and a key stimulus for PASMC proliferation and migration, both contributing to the development of pulmonary vascular remodeling. PASMC from patients with idiopathic PAH (IPAH) have increased resting [Ca2+]cyt and enhanced Ca2+ influx. Enhanced Ca2+ entry into PASMC due to upregulation of membrane receptors and/or Ca2+ channels may contribute to PASMC contraction and proliferation and to pulmonary vasoconstriction and pulmonary vascular remodeling. We have shown that the extracellular Ca2+-sensing receptor (CaSR), which is a member of G protein-coupled receptor (GPCR) subfamily C, is upregulated, and the extracellular Ca2+-induced increase in [Ca2+]cyt is enhanced in PASMC from patients with IPAH in comparison to PASMC from normal subjects. Pharmacologically blockade of CaSR significantly attenuate the development and progression of experimental pulmonary hypertension in animals. Additionally, we have demonstrated that dihydropyridine Ca2+ channel blockers (e.g., nifedipine), which are used to treat PAH patients but are only effective in 15-20% of patients, activate CaSR resulting in an increase in [Ca2+]cyt in IPAH-PASMC, but not normal PASMC. Our data indicate that CaSR functionally couples with transient receptor potential canonical (TRPC) channels to mediate extracellular Ca2+-induced Ca2+ influx and increase in [Ca2+]cyt in IPAH-PASMC. Upregulated CaSR is necessary for the enhanced extracellular Ca2+-induced increase in [Ca2+]cyt and the augmented proliferation of PASMC in patients with IPAH. This review will highlight the pathogenic role of CaSR in the development and progression of PAH

Mizoribine, tacrolimus, and corticosteroid combination therapy successfully induces remission in patients with lupus nephritis

Conventional cyclophosphamide-based treatment regimens for lupus nephritis (LN) are still not considered to be optimal. The aim of this study was to evaluate the efficacy and safety of mizoribine, tacrolimus, and corticosteroid combination therapy for LN. We retrospectively evaluated a combination treatment of mizoribine and tacrolimus with corticosteroids as induction therapy in eight newly diagnosed systemic lupus erythematosus (SLE) patients with biopsy-proven LN. All patients were women, and their mean [standard deviation (SD)] age was 48.5 (20) years. All patients (100 %) had positive anti-double-stranded DNA (anti-dsDNA) antibody titers, and four (50.0 %) were nephrotic. Mean (SD) serum creatinine and daily proteinuria levels were 0.72 (0.4) mg/dl (range 0.33-1.55 mg/dl) and 4.56 (2.8) g (range 0.77-8.2 g), respectively. By month 2, significant improvements in the anti-dsDNA antibody titers, levels of proteinuria, serum albumin, and C3, and SLE disease activity index score were observed. By month 6, seven patients (87.5 %) were in complete remission, with normalized levels of both proteinuria and serum creatinine. This pilot study suggests that mizoribine and tacrolimus treatment with corticosteroids is well tolerated and may prove to be an optimal alternative remission-inducing regimen for LN

Aortic pathology from protein kinase G activation is prevented by an antioxidant vitamin B12 analog.

People heterozygous for an activating mutation in protein kinase G1 (PRKG1, p.Arg177Gln) develop thoracic aortic aneurysms and dissections (TAAD) as young adults. Here we report that mice heterozygous for the mutation have a three-fold increase in basal protein kinase G (PKG) activity, and develop age-dependent aortic dilation. Prkg1R177Q/+ aortas show increased smooth muscle cell apoptosis, elastin fiber breaks, and oxidative stress compared to aortas from wild type littermates. Transverse aortic constriction (TAC)-to increase wall stress in the ascending aorta-induces severe aortic pathology and mortality from aortic rupture in young mutant mice. The free radical-neutralizing vitamin B12-analog cobinamide completely prevents age-related aortic wall degeneration, and the unrelated anti-oxidant N-acetylcysteine ameliorates TAC-induced pathology. Thus, increased basal PKG activity induces oxidative stress in the aorta, raising concern about the widespread clinical use of PKG-activating drugs. Cobinamide could be a treatment for aortic aneurysms where oxidative stress contributes to the disease, including Marfan syndrome

Pathogenic Role of mTORC1 and mTORC2 in Pulmonary Hypertension.

Concentric lung vascular wall thickening due to enhanced proliferation of pulmonary arterial smooth muscle cells is an important pathological cause for the elevated pulmonary vascular resistance reported in patients with pulmonary arterial hypertension. We identified a differential role of mammalian target of rapamycin (mTOR) complex 1 and complex 2, two functionally distinct mTOR complexes, in the development of pulmonary hypertension (PH). Inhibition of mTOR complex 1 attenuated the development of PH; however, inhibition of mTOR complex 2 caused spontaneous PH, potentially due to up-regulation of platelet-derived growth factor receptors in pulmonary arterial smooth muscle cells, and compromised the therapeutic effect of the mTOR inhibitors on PH. In addition, we describe a promising therapeutic strategy using combination treatment with the mTOR inhibitors and the platelet-derived growth factor receptor inhibitors on PH and right ventricular hypertrophy. The data from this study provide an important mechanism-based perspective for developing novel therapies for patients with pulmonary arterial hypertension and right heart failure

Efficacy and safety of nintedanib in Japanese patients with progressive fibrosing interstitial lung diseases : Subgroup analysis of the randomised, double-blind, placebo-controlled, phase 3 INBUILD trial

Background: The efficacy of nintedanib in progressive fibrosing interstitial lung diseases (ILDs) was demonstrated in the randomised, double-blind, placebo-controlled INBUILD trial. This subgroup analysis evaluated the efficacy and safety of nintedanib in the Japanese population. Methods: Patients with progressive fibrosing ILDs (evaluated by physicians within 24 months of screening) were randomised (1:1) to twice-daily 150-mg nintedanib or placebo; treatment continued until the last patient completed 52 weeks. The primary endpoint was the annual rate of decline in forced vital capacity (FVC) over 52 weeks. Time-to-first acute ILD exacerbation or death and time-to-death up until the last patient had completed the week 52 visit were evaluated. This subgroup analysis included 108 Japanese patients. Results: The adjusted annual rates of FVC decline (mL/year) over 52 weeks for Japanese patients were −148.31 (nintedanib) and −240.36 (placebo), adjusted difference: 92.05 (95% CI: −10.69–194.80) and for non-Japanese patients were −67.41 (nintedanib) and −177.65 (placebo), adjusted difference: 110.24 (95% CI: 64.97–155.52). No heterogeneity in treatment effect between Japanese and non-Japanese subgroups was observed (treatment-by-subgroup interaction, p = 0.75). The risks of “acute exacerbation or death” (hazard ratio, 0.30 [95% CI: 0.10–0.91]) and mortality (hazard ratio, 0.54 [95% CI: 0.14–2.11]) in Japanese patients were numerically lower for nintedanib than placebo. There were no new or unexpected safety findings. Conclusions: In Japanese patients, nintedanib slowed ILD progression, evidenced by a reduction in the annual rate of decline in FVC vs placebo. The efficacy and safety of nintedanib in Japanese patients were consistent with the overall INBUILD population

Testis-Specific Histone Variant H3t Gene Is Essential for Entry into Spermatogenesis

Jun Ueda, Akihito Harada, Takashi Urahama, Shinichi Machida, Kazumitsu Maehara, Masashi Hada, Yoshinori Makino, Jumpei Nogami, Naoki Horikoshi, Akihisa Osakabe, Hiroyuki Taguchi, Hiroki Tanaka, Hiroaki Tachiwana, Tatsuma Yao, Minami Yamada, Takashi Iwamoto, Ayako Isotani, Masahito Ikawa, Taro Tachibana, Yuki Okada, Hiroshi Kimura, Yasuyuki Ohkawa, Hitoshi Kurumizaka, Kazuo Yamagata, Testis-Specific Histone Variant H3t Gene Is Essential for Entry into Spermatogenesis, Cell Reports, Volume 18, Issue 3, 2017, Pages 593-600, ISSN 2211-1247, https://doi.org/10.1016/j.celrep.2016.12.065

A novel transgenic chimaeric mouse system for the rapid functional evaluation of genes encoding secreted proteins

A major challenge of the post-genomic era is the functional characterization of anonymous open reading frames (ORFs) identified by the Human Genome Project. In this context, there is a strong requirement for the development of technologies that enhance our ability to analyze gene functions at the level of the whole organism. Here, we describe a rapid and efficient procedure to generate transgenic chimaeric mice that continuously secrete a foreign protein into the systemic circulation. The transgene units were inserted into the genomic site adjacent to the endogenous immunoglobulin (Ig) κ locus by homologous recombination, using a modified mouse embryonic stem (ES) cell line that exhibits a high frequency of homologous recombination at the Igκ region. The resultant ES clones were injected into embryos derived from a B-cell-deficient host strain, thus producing chimaerism-independent, B-cell-specific transgene expression. This feature of the system eliminates the time-consuming breeding typically implemented in standard transgenic strategies and allows for evaluating the effect of ectopic transgene expression directly in the resulting chimaeric mice. To demonstrate the utility of this system we showed high-level protein expression in the sera and severe phenotypes in human EPO (hEPO) and murine thrombopoietin (mTPO) transgenic chimaeras

DOCK2 is involved in the host genetics and biology of severe COVID-19

「コロナ制圧タスクフォース」COVID-19疾患感受性遺伝子DOCK2の重症化機序を解明 --アジア最大のバイオレポジトリーでCOVID-19の治療標的を発見--. 京都大学プレスリリース. 2022-08-10.Identifying the host genetic factors underlying severe COVID-19 is an emerging challenge. Here we conducted a genome-wide association study (GWAS) involving 2, 393 cases of COVID-19 in a cohort of Japanese individuals collected during the initial waves of the pandemic, with 3, 289 unaffected controls. We identified a variant on chromosome 5 at 5q35 (rs60200309-A), close to the dedicator of cytokinesis 2 gene (DOCK2), which was associated with severe COVID-19 in patients less than 65 years of age. This risk allele was prevalent in East Asian individuals but rare in Europeans, highlighting the value of genome-wide association studies in non-European populations. RNA-sequencing analysis of 473 bulk peripheral blood samples identified decreased expression of DOCK2 associated with the risk allele in these younger patients. DOCK2 expression was suppressed in patients with severe cases of COVID-19. Single-cell RNA-sequencing analysis (n = 61 individuals) identified cell-type-specific downregulation of DOCK2 and a COVID-19-specific decreasing effect of the risk allele on DOCK2 expression in non-classical monocytes. Immunohistochemistry of lung specimens from patients with severe COVID-19 pneumonia showed suppressed DOCK2 expression. Moreover, inhibition of DOCK2 function with CPYPP increased the severity of pneumonia in a Syrian hamster model of SARS-CoV-2 infection, characterized by weight loss, lung oedema, enhanced viral loads, impaired macrophage recruitment and dysregulated type I interferon responses. We conclude that DOCK2 has an important role in the host immune response to SARS-CoV-2 infection and the development of severe COVID-19, and could be further explored as a potential biomarker and/or therapeutic target