Hypoxia promotes fibrogenesis in human renal fibroblasts. indicator of progression [3]. Tubulointersititial fibrosisBackground. The mechanisms underlying progressive renal is characterized by tubular dilation and atrophy, an infibrosis are unknown, but the common association of fibrosis crease in interstitial cell number, activation of fibroblasts and microvascular loss suggests that hypoxia per se may be a to myofibroblasts with increased expression of ␣-smooth fibrogenic stimulus.muscle actin (␣-SMA), obliteration of the microvascula-Methods. To determine whether human renal fibroblasts (HRFs), the primary matrix-producing cells in the tubulointersture, and accumulation of extracellular matrix (ECM) titium, possess oxygen-sensitive responses relevant to fibro-[1-5]. Despite the large number of studies documenting genesis, cells were exposed to 1% O 2 in vitro. changes in a variety of ECM proteins and growth factors, Results. Hypoxia simultaneously stimulated extracellular most notably transforming growth factor-␤1 (TGF-␤1) matrix synthesis and suppressed turnover with increased pro-[5, 6], in models of PRD and in human pathologies, the duction of collagen ␣1(I) (Coll-I), decreased expression of collagenase, and increased tissue inhibitor of metalloproteinase mechanisms underlying accumulation of ECM remain (TIMP)-1. These effects are time dependent, require new RNA obscure. In trying to understand the association of gloand protein synthesis, and are specific to hypoxia. The changes merular damage, interstitial fibrosis, and tubular atrophy in Coll-I and TIMP-1 gene expression involve a heme-protein in PRD, we have proposed a sequence of events that O 2 sensor and protein kinase-and tyrosine kinase-mediated signaling. Although hypoxia induced transforming growth factor-␤1 ascribes a central role to microvascular compromise and (TGF-␤1), neutralizing anti-TGF-␤1-antibody did not block hypoxia in the pathogenesis of interstitial fibrosis [7, 8]. hypoxia-induced Coll-I and TIMP-1 mRNA expression. Fur-Hypoxia can regulate expression of a wide variety thermore, hypoxic-cell conditioned-medium had no effect on of genes that may be induced or suppressed by either the expression of these mRNAs in naive fibroblasts, suggesting transcriptional and post-transcriptional mechanisms [redirect effects on gene transcription. Transient transfections identified a hypoxia response element (HRE) in the TIMP-1 viewed in 9-11]. Hypoxia response elements (HREs) promoter and demonstrated HIF-1-dependent promoter actihave been identified in the regulatory regions of a numvation by decreased ambient pO 2 .ber of genes and contain consensus binding sites for the Conclusions. These data suggest that hypoxia co-ordinately transcription factor hypoxia-inducible factor-1 (HIF-1) up-regulates matrix production and decreases turnover in renal [12][13][14]. A variety of other transcription factors are infibroblasts. The results support a role for hypoxia in the pathogenesis of fibrosis and provide evidence for novel, direct hypduced by low O 2 ,...

The mechanisms underlying the progressive fibrosis that characterises end-stage renal disease in vivo remain to be established but hypoxia, as a result of microvascular injury and loss, has been suggested to play an important role. In support of this hypothesis, in vitro studies show that hypoxia (1% O₂) induces a fibrogenic phenotype in human renal tubular endothelia, interstitial fibroblasts and microvascular endothelial cells, simultaneously increasing extracellular matrix (ECM) production and decreasing turnover via effectors on matrix-degrading enzymes and their inhibitors. The effects of hypoxia on ECM metabolism are independent of hypoxia-induced growth factors and are mediated by a haem-protein sensor and activation of both protein kinase C- and tyrosine kinase-mediated signal transduction pathways. De novo gene transcription is regulated by both hypoxia-inducible factor-1-dependent and -independent mechanisms. Further understanding of the molecular mechanisms by which decreased oxygen alters expression of genes involved in ECM metabolism in renal cells may provide new insights into the pathogenesis of fibrosis and identify novel avenues for intervention.

Background Convalescent plasma has been widely used to treat COVID-19 and is under investigation in numerous randomized clinical trials, but results are publicly available only for a small number of trials. The objective of this study was to assess the benefits of convalescent plasma treatment compared to placebo or no treatment and all-cause mortality in patients with COVID-19, using data from all available randomized clinical trials, including unpublished and ongoing trials (Open Science Framework, https://doi.org/10.17605/OSF.IO/GEHFX). Methods In this collaborative systematic review and meta-analysis, clinical trial registries (ClinicalTrials.gov, WHO International Clinical Trials Registry Platform), the Cochrane COVID-19 register, the LOVE database, and PubMed were searched until April 8, 2021. Investigators of trials registered by March 1, 2021, without published results were contacted via email. Eligible were ongoing, discontinued and completed randomized clinical trials that compared convalescent plasma with placebo or no treatment in COVID-19 patients, regardless of setting or treatment schedule. Aggregated mortality data were extracted from publications or provided by investigators of unpublished trials and combined using the Hartung–Knapp–Sidik–Jonkman random effects model. We investigated the contribution of unpublished trials to the overall evidence. Results A total of 16,477 patients were included in 33 trials (20 unpublished with 3190 patients, 13 published with 13,287 patients). 32 trials enrolled only hospitalized patients (including 3 with only intensive care unit patients). Risk of bias was low for 29/33 trials. Of 8495 patients who received convalescent plasma, 1997 died (23%), and of 7982 control patients, 1952 died (24%). The combined risk ratio for all-cause mortality was 0.97 (95% confidence interval: 0.92; 1.02) with between-study heterogeneity not beyond chance (I2 = 0%). The RECOVERY trial had 69.8% and the unpublished evidence 25.3% of the weight in the meta-analysis. Conclusions Convalescent plasma treatment of patients with COVID-19 did not reduce all-cause mortality. These results provide strong evidence that convalescent plasma treatment for patients with COVID-19 should not be used outside of randomized trials. Evidence synthesis from collaborations among trial investigators can inform both evidence generation and evidence application in patient care.

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In the enhancer region of the human type I collagen alpha 2 (COL1A2) gene, we identified cis-elements for the transcription factor CUX1. However, the role of CUX1 in fibrosis remains unclear. Here we investigated the role of CUX1 in the regulation of COL1 expression and delineated the mechanisms underlying the regulation of COL1A2 expression by CUX1 in systemic sclerosis (SSc) lung fibroblasts. The binding of CUX1 to the COL1A2 enhancer region was assessed using electrophoretic mobility shift assays after treatment with transforming growth factor (TGF)-β. Subsequently, the protein expression levels of CUX1 isoforms were determined using Western blotting. Finally, the expression levels of COL1 and fibrosis-related cytokines, including CTGF, ET-1, Wnt1 and β-catenin were determined. The binding of CUX1 isoforms to the COL1A2 enhancer region increased after TGF-β treatment. TGF-β also increased the protein levels of the CUX1 isoforms p200, p150, p110, p75, p30 and p28. Moreover, SSc lung fibroblasts showed higher levels of CUX1 isoforms than normal lung fibroblasts, and treatment of SSc lung fibroblasts with a cathepsin L inhibitor (IW-CHO) decreased COL1 protein expression and reduced cell size, as measured using immunocytochemistry. In SSc and diffuse alveolar damage lung tissue sections, CUX1 localised within α-smooth muscle actin-positive cells. Our results suggested that CUX1 isoforms play vital roles in connective tissue deposition during wound repair and fibrosis.