Background/Aims-The pathogenesis of idiopathic pulmonary fibrosis (IPF)/usual interstitial pneumonia (UIP), a chronic and incurable human respiratory disease, is not well established. This study was designed to investigate whether the apoptosis of type II pneumocytes could be the precipitating factor in the pathogenesis of IPF. Methods-Nineteen specimens obtained by retrospective review of the medical and pathological records of 55 patients with IPF, four normal subjects, and 10 disease control lungs were analysed. The selected specimens had normal alveoli with intervening patchy scarring of the lung parenchyma, fulfilling the pathological criteria for UIP. To identify individual cells undergoing apoptosis in the normal alveoli, electron microscopy and in situ end labelling of fragmented DNA were performed on paraYn wax embedded sections using digoxigenin-11-dUTP and the enzyme terminal deoxynucleotidyl transferase. (J Clin Pathol 2001;54:132-138) Results-Apoptosis

Our findings indicate that TiO₂ particles induce a Th1-mediated inflammatory response in the small bowel in mice.

INTRODUCTION: Elevated D-dimer is a predictor of severity and mortality in COVID-19 patients and heparin use during in-hospital stay has been associated with decreased mortality. COVID-19 patient autopsies have revealed thrombi in the microvasculature, suggesting intravascular coagulation as a prominent feature of organ failure in these patients. Interestingly, in COVID-19, pulmonary compliance is preserved despite severe hypoxemia corroborating the hypothesis that perfusion mismatch may play a significant role in the development of respiratory failure. METHODS: We describe a series of 27 consecutive COVID-19 patients admitted to Sirio-Libanes Hospital in Sao Paulo-Brazil and treated with heparin in therapeutic doses tailored to clinical severity. RESULTS AND DISCUSSION: PaO2/FiO2 ratio increased significantly over the 72 hours following the start of anticoagulation, from 254(SD 90) to 325(SD 80), p=0.013, and 81% of the patients were discharged home within a mean time of 11.4 (SD 7.9) days. Most mechanically ventilated patients (67%) were extubated within 12.5(SD 5.7) days. There were no bleeding complications or fatal events. Even though this uncontrolled case series does not offer absolute proof of DIC as the underlying mechanism of respiratory failure in COVID-19, patients positive response to tailored dose heparinization contributes to the understanding of the pathophysiological mechanism of the disease and provides valuable information for the treatment of these very sick patients while we await the results of further prospective controlled studies.

The infection by the Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes major public health concern and economic burden. Although clinically approved drugs have been repurposed to treat individuals with 2019 Coronavirus disease (COVID-19), the lack of safety studies and limited efficiency as well jeopardize clinical benefits. Daclatasvir and sofosbuvir (SFV) are clinically approved direct-acting antivirals (DAA) against hepatitis C virus (HCV), with satisfactory safety profile. In the HCV replicative cycle, daclatasvir and SFV target the viral enzymes NS5A and NS5B, respectively. NS5A is endowed with pleotropic activities, which overlap with several proteins from SARS-CoV-2. HCV NS5B and SARS-CoV-2 nsp12 are RNA polymerases that share homology in the nucleotide uptake channel. These characteristics of the HCV and SARS-CoV-2 motivated us to further study the activity of daclatasvir and SFV against the new coronavirus. Daclatasvir consistently inhibited the production of infectious SARS-CoV-2 virus particles in Vero cells, in the hepatoma cell line HuH-7 and in type II pneumocytes (Calu-3), with potencies of 0.8, 0.6 and 1.1 μM, respectively. Daclatasvir targeted early events during SARS-CoV-2 replication cycle and prevented the induction of IL-6 and TNF-α, inflammatory mediators associated with the cytokine storm typical of SARS-CoV-2 infection. Sofosbuvir, although inactive in Vero cells, displayed EC50 values of 6.2 and 9.5 μM in HuH-7 and Calu-3 cells, respectively. Our data point to additional antiviral candidates, in especial daclatasvir, among drugs overlooked for COVID-19, that could immediately enter clinical trials.

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