Immunohistochemical profile of cell cycle control, proliferation and differentiation proteins of the pulmonary atypical alveolar epithelium with COVID-19-induced diffuse alveolar damage as compared to pulmonary [lepidic-growth] adenocarcinoma.

We aim aim to compare immunophenotypic charac-teritics of atypical epithelium (AE) with COVID-19-induced diffuse alveolar damage (DAD) and pulmonary lepidic-growth adenocarcinoma, accounting for cell cycle control, proliferation and differentiation]. Methods. We examined pulmonary tissue specimens from twenty-four fatal cases of CO VID-19-induced acute respiratory damage syndrome confirmed by autopsy (Group 1) and four cases of pulmonary lepidic-growth adenocarcinoma (Group 2). Perpendicular dimensions of 10 nuclei were measured on the H&E slides, means of their sums of products (SPNM) were calculated. We have used p53, Ki67, pi6, p63 antibodies for immunohistochemical staining in each case. We evaluate colour intensity, rate of stained cells of AE and the product of these parameters. We evaluated separately Nuclear and cyto-plasmic staining (couple) and only cytoplasmic staining (cyt) for pi6 expression. We measured proliferative index only at KI-67 stained slides. U-test and Spearman rank correlation test were used for statistical analysis. Results. Expression of p63 was higher in group 1 (p=0.001), while pi6 was more frequently expressed in group 2 (p=0.002). We have found no statistically significant differences (p>0.1) in the p53 and Ki67 expression. Group 1 showed There was negative correlation between the number of days from onset of symptoms and the following variables: Ki67 (r=M).587, p=0.003);SPNM (r 0.406, p=0.049). Conclusion. The present study has shown heterogeneity in levels of cell cycle control expression, proliferation and differentiation of atypical epithelium in the pulmonary lep-idic-growth adenocarcinoma and CO VID-19-induced diffuse alveolar damage.Copyright © 2022 Izdatel'stvo Meditsina. All rights reserved.

Host Recovery from Respiratory Viral Infection.

Emerging and re-emerging respiratory viral infections pose a tremendous threat to human society, as exemplified by the ongoing COVID-19 pandemic. Upon viral invasion of the respiratory tract, the host initiates coordinated innate and adaptive immune responses to defend against the virus and to promote repair of the damaged tissue. However, dysregulated host immunity can also cause acute morbidity, hamper lung regeneration, and/or lead to chronic tissue sequelae. Here, we review our current knowledge of the immune mechanisms regulating antiviral protection, host pathogenesis, inflammation resolution, and lung regeneration following respiratory viral infections, mainly using influenza virus and SARS-CoV-2 infections as examples. We hope that this review sheds light on future research directions to elucidate the cellular and molecular cross talk regulating host recovery and to pave the way to the development of pro-repair therapeutics to augment lung regeneration following viral injury.

Effect of aerobic exercise on lung regeneration and inflammation in mice.

Aerobic exercise is well recognized to be beneficial to physical and mental health. Many studies have shown that aerobic exercise can improve the human immune system, but whether it could affect lung regeneration and inflammation remained unclear. Bronchioloalveolar stem cells (BASCs) play a key role in lung regeneration and repair, but it is unclear whether aerobic exercise affects BASCs. Here, we randomly divided 8 weeks old male mice into three groups: the control group without any aerobic exercise; the rest group which received 2 weeks of aerobic exercise (running wheel training) plus 5 days' rest, and the exercise group which received 2 weeks of aerobic exercise without any rest. Our data indicated that mice in the exercise group had significantly increased BASCs compared to the control group, such difference did not exist in the rest group. Furthermore, the immune profiling suggested that lung inflammation was slightly up-regulated in the exercise group, particularly the inflammatory monocytes and IL-17A+ T cells. In conclusion, we provide direct evidence showing that aerobic exercise can facilitate lung regeneration with mild inflammatory effect, this finding is of great importance in the current COVID-19 pandemic.

Contribution of Trp63CreERT2-labeled cells to alveolar regeneration is independent of tuft cells.

Viral infection often causes severe damage to the lungs, leading to the appearance of ectopic basal cells (EBCs) and tuft cells in the lung parenchyma. Thus far, the roles of these ectopic epithelial cells in alveolar regeneration remain controversial. Here, we confirm that the ectopic tuft cells are originated from EBCs in mouse models and COVID-19 lungs. The differentiation of tuft cells from EBCs is promoted by Wnt inhibition while suppressed by Notch inhibition. Although progenitor functions have been suggested in other organs, pulmonary tuft cells don't proliferate or give rise to other cell lineages. Consistent with previous reports, Trp63CreERT2 and KRT5-CreERT2-labeled ectopic EBCs do not exhibit alveolar regeneration potential. Intriguingly, when tamoxifen was administrated post-viral infection, Trp63CreERT2 but not KRT5-CreERT2 labels islands of alveolar epithelial cells that are negative for EBC biomarkers. Furthermore, germline deletion of Trpm5 significantly increases the contribution of Trp63CreERT2-labeled cells to the alveolar epithelium. Although Trpm5 is known to regulate tuft cell development, complete ablation of tuft cell production fails to improve alveolar regeneration in Pou2f3-/- mice, implying that Trpm5 promotes alveolar epithelial regeneration through a mechanism independent of tuft cells.

Stem cells, cell therapies, and bioengineering in lung biology and disease 2021.

The 9th biennial conference titled "Stem Cells, Cell Therapies, and Bioengineering in Lung Biology and Diseases" was hosted virtually, due to the ongoing COVID-19 pandemic, in collaboration with the University of Vermont Larner College of Medicine, the National Heart, Lung, and Blood Institute, the Alpha-1 Foundation, the Cystic Fibrosis Foundation, and the International Society for Cell & Gene Therapy. The event was held from July 12th through 15th, 2021 with a pre-conference workshop held on July 9th. As in previous years, the objectives remained to review and discuss the status of active research areas involving stem cells (SCs), cellular therapeutics, and bioengineering as they relate to the human lung. Topics included 1) technological advancements in the in situ analysis of lung tissues, 2) new insights into stem cell signaling and plasticity in lung remodeling and regeneration, 3) the impact of extracellular matrix in stem cell regulation and airway engineering in lung regeneration, 4) differentiating and delivering stem cell therapeutics to the lung, 5) regeneration in response to viral infection, and 6) ethical development of cell-based treatments for lung diseases. This selection of topics represents some of the most dynamic and current research areas in lung biology. The virtual workshop included active discussion on state-of-the-art methods relating to the core features of the 2021 conference, including in situ proteomics, lung-on-chip, induced pluripotent stem cell (iPSC)-airway differentiation, and light sheet microscopy. The conference concluded with an open discussion to suggest funding priorities and recommendations for future research directions in basic and translational lung biology.