Abstract-The mechanisms by which persistent proteinuria induces interstitial inflammation and fibrosis are not well known, although nuclear factor-B (NF-B), which regulates the transcription of many genes involved in renal injury, could be implicated. In rats with intense proteinuria, we studied the renal activation of NF-B as well as the potential involvement of the vasoactive hormones angiotensin II (Ang II) and endothelin-1 (ET-1). Uninephrectomized Wistar-Kyoto rats receiving 1 g/d of BSA had proteinuria but no renal morphological lesions at day 1. By contrast, tubular atrophy and/or dilation and mononuclear cell infiltration were observed after 8 or 28 days of BSA administration, coinciding with maximal proteinuria. In relation to control uninephrectomized rats, the renal cortex of nephritic rats showed an increment in the activation of NF-B at all time periods studied. By in situ Southwestern histochemistry, NF-B activity was mainly localized in proximal tubules, interstitial mononuclear cells, and, to a lesser extent, the glomeruli. The administration of the ACE inhibitor quinapril plus the ET A /ET B receptor antagonist bosentan during 28 days to BSA-overloaded animals diminished proteinuria, renal lesions, and NF-B activity more markedly than single drugs. Cultured tubular epithelial cells exposed to BSA revealed an intense NF-B activation in a time-and dose-dependent manner. Incubation of cells with receptor antagonists of Ang II (AT 1 : losartan and AT 2 : PD-123,319) or ET-1 (ET A : BQ123 and ET B : IRL1038) inhibited significantly the BSA-induced NF-B activity (90%, 75%, 90%, and 60% of inhibition versus basal, respectively). Our results show that overload proteinuria causes NF-B activation in tubular epithelial cells both in vivo and in vitro. The vasoactive peptides Ang II and ET-1 appear to be implicated in this effect. The results reveal a novel mechanism of perpetuation of renal damage induced by persistent proteinuria.

The spectrum of COVID-19 infection includes acute respiratory distress syndrome (ARDS) and macrophage activation syndrome (MAS), although the histological basis for these disorders has not been thoroughly explored. Post-mortem pulmonary and bone marrow biopsies were performed in 33 patients. Samples were studied with a combination of morphological and immunohistochemical techniques. Bone marrow studies were also performed in three living patients. Bone marrow post-mortem studies showed striking lesions of histiocytic hyperplasia with hemophagocytosis (HHH) in most (16/17) cases. This was also observed in three alive patients, where it mimicked the changes observed in hemophagocytic histiocytosis. Pulmonary changes included a combination of diffuse alveolar damage with fibrinous microthrombi predominantly involving small vessels, in particular the alveolar capillary. These findings were associated with the analytical and clinical symptoms, which helps us understand the respiratory insufficiency and reveal the histological substrate for the macrophage activation syndrome-like exhibited by these patients. Our results confirm that COVID-19 infection triggers a systemic immune-inflammatory disease and allow specific therapies to be proposed.

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Background-We recently obtained evidence demonstrating that cultured bovine endothelial cells contain cytosolic proteins that form complexes with the 3Ј-untranslated region of endothelial nitric oxide synthase (eNOS) mRNA and are associated with its destabilization. The aim of this study was to determine the presence of such proteins and eNOS expression in hypercholesterolemic rabbits as an in vivo model of endothelial dysfunction. Methods and Results-Endothelium-dependent relaxation to acetylcholine and the calcium ionophore A23187 was reduced in aortic segments from hypercholesterolemic rabbits compared with controls. Treatment of hypercholesterolemic rabbits with cerivastatin (0.1 mg · kg body wt Ϫ1 · d Ϫ1 ) restored endothelium-dependent relaxation. Aortic eNOS expression was reduced in hypercholesterolemic rabbits and was accompanied by enhanced binding activity of a 60-kDa cytosolic protein and reduced stability of eNOS mRNA. Cerivastatin treatment upregulated eNOS expression and reduced the interaction of the cytosolic protein with the 3Ј-untranslated region of eNOS mRNA. Mononuclear cells from hypercholesterolemic rabbits also showed a marked reduction of eNOS expression and eNOS mRNA stability and an increase in binding activity of the cytosolic protein, which were also prevented by cerivastatin treatment.Conclusions-These results demonstrate the presence of a 60-kDa protein that binds to eNOS mRNA and reductions in eNOS expression in both vascular wall and mononuclear cells that are prevented by cerivastatin.