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Severe COVID-19 is associated with epithelial and endothelial barrier dysfunction within the lung as well as in distal organs. While it is appreciated that an exaggerated inflammatory response is associated with barrier dysfunction, the triggers of vascular leak are unclear. Here, we report that cell-intrinsic interactions between the Spike (S) glycoprotein of SARS-CoV-2 and epithelial/endothelial cells are sufficient to induce barrier dysfunction in vitro and vascular leak in vivo, independently of viral replication and the ACE2 receptor. We identify an S-triggered transcriptional response associated with extracellular matrix reorganization and TGF-β signaling. Using genetic knockouts and specific inhibitors, we demonstrate that glycosaminoglycans, integrins, and the TGF-β signaling axis are required for S-mediated barrier dysfunction. Notably, we show that SARS-CoV-2 infection caused leak in vivo, which was reduced by inhibiting integrins. Our findings offer mechanistic insight into SARS-CoV-2-triggered vascular leak, providing a starting point for development of therapies targeting COVID-19., (© 2022. The Author(s).)

Background: Alport syndrome (AS), a hereditary type IV collagen nephropathy, is a major cause of end-stage renal disease in young people. About 85% of the cases are X-linked (ATS), due to mutations in the COL4A5 gene. Rarely, families have a contiguous gene deletion comprising at least exon 1 of COL4A5 and the first exons of COL4A6, associated with the development of diffuse leiomyomatosis (ATS-DL). We report three novel deletions identified in families with AS, one of which challenges the current concepts on genotype-phenotype correlations of ATS/ATS-DL., Methods: In the setting of a multicentric study aiming to describe the genetic epidemiology and molecular pathology of AS in Portugal, three novel COL4A5 deletions were identified in two families with x-linked Alport syndrome (ATS) and in one family with ATS-DL. These mutations were initially detected by PCR and Multiplex Ligation-dependent Probe Amplification, and further mapped by high-resolution X chromosome-specific oligo-array and PCR., Results: In the ATS-DL family, a COL4A5 deletion spanning exons 2 through 51, extending distally beyond COL4A5 but proximally not into COL4A6, segregated with the disease phenotype. A COL4A5 deletion encompassing exons 2 through 29 was identified in one of the ATS families. In the second ATS family, a deletion of exon 13 of COL4A5 through exon 3 of COL4A6 was detected., Conclusions: These observations suggest that deletion of the 5' exons of COL4A6 and of the common promoter of the COL4A5 and COL4A6 genes is not essential for the development of leiomyomatosis in patients with ATS, and that COL4A5_COL4A6 deletions extending into COL4A6 exon 3 may not result in ATS-DL.

In this study we analyse the effects of the administration of recombinant human erythropoietin (rHuEpo) during 12 months to correct the anaemia in a group of 17 patients (9 men and 8 women; mean age 52.7 +/- 13.7; range 23 to 68 years) with end-stage renal disease (ESRD) on chronic haemodialysis (HD) for a range of 14 to 126 months (mean 43.1 +/- 29.6). In the correction period the rHuEpo was started at 50 U/Kg i.v. 3 times a week, immediately after each HD. This dose was maintained during 4 weeks and then increased in 25 U/Kg steps until haemoglobin (Hb) levels of 12 g/dl or a maximum dose of 100 U/Kg were reached. During the long-term maintenance period the individual rHuEpo dose was adjusted to keep the Hb constant at the target level of 10-12 g/dl. Baseline blood tests were done before the beginning of the treatment and every months afterwards. The levels of Hb increased significantly in week 4 and at the end of the first 3 month only 4 patients had no answer to rHuEpo. These patients had baseline serum ferritin levels below 100 ng/ml and responded well when this defficiency was corrected with oral iron. When levels of 30-35 vol% haematocrit (Hct) were reached the dose of rHuEpo could be reduced (150 to 200 U/Kg/week). The serum ferritin levels decreased 51% from a mean baseline level of 247.8 +/- 196 to 121.1 +/- 154.9 ng/ml with the onset of the maintenance phase (p less than 0.05).

A group of 50 patients (26 men and 24 women, mean age 50 +/- 19 years and range 21 to 67) on chronic hemodialysis (HD) and with basal levels of hemoglobin (Hb) less than or equal to 8 g/dl was treated with recombinant human erythropoietin (r-HuEpo) during 3 months. r-HuEpo was started at 50 U/kg I.V. 3 times a week, immediately after each session of HD, for 4 weeks, and this dose was increased in steps of 25 U/kg until a Hb level of 12 g/dl or a maximum dose of 100 U/kg were reached. Complete blood counts and biochemical profile were performed before the first dose of r-HuEpo and once weekly and monthly respectively during the period of treatment. In 8 patients the red-cell life span was studied with cromium 51 labelled erythrocytes just before and after treatment. One patient had a grand mal seizure and the r-HuEpo was discontinued. In 44 patients the mean hematocrit increased from 21.8% to 32.1% and in the other 5 there were no response because of iron deficiency. There were no changes in leucocytes and platelets counts and consistent decreases in iron and ferritin serum concentrations were observed despite oral supplementation of iron. In the 8 patients studied the shortened erythrocyte survival did not suffer any significant variation with r-HuEpo. Predialysis creatinine, urea and phosphorus blood levels increased significantly at 3th month of treatment but there was no increase in potassium. In 32.6% of previously normotensive and hypertensive patients an increase in blood pressure was founded. Thrombosis of arteriovenous fistulas and other severe clinical side effects were not observed.(ABSTRACT TRUNCATED AT 250 WORDS)