Modeling of Respiratory Diseases Evolving with Fibrosis from Organoids Derived from Human Pluripotent Stem Cells.

Respiratory disease is one of the leading causes of morbidity and mortality worldwide. There is no cure for most diseases, which are treated symptomatically. Hence, new strategies are required to deepen the understanding of the disease and development of therapeutic strategies. The advent of stem cell and organoid technology has enabled the development of human pluripotent stem cell lines and adequate differentiation protocols for developing both airways and lung organoids in different formats. These novel human-pluripotent-stem-cell-derived organoids have enabled relatively accurate disease modeling. Idiopathic pulmonary fibrosis is a fatal and debilitating disease that exhibits prototypical fibrotic features that may be, to some extent, extrapolated to other conditions. Thus, respiratory diseases such as cystic fibrosis, chronic obstructive pulmonary disease, or the one caused by SARS-CoV-2 may reflect some fibrotic aspects reminiscent of those present in idiopathic pulmonary fibrosis. Modeling of fibrosis of the airways and the lung is a real challenge due to the large number of epithelial cells involved and interaction with other cell types of mesenchymal origin. This review will focus on the status of respiratory disease modeling from human-pluripotent-stem-cell-derived organoids, which are being used to model several representative respiratory diseases, such as idiopathic pulmonary fibrosis, cystic fibrosis, chronic obstructive pulmonary disease, and COVID-19.

The Role of Endoplasmic Reticulum Stress in Differentiation of Cells of Mesenchymal Origin.

Endoplasmic reticulum (ER) is a multifunctional membrane-enclosed organelle. One of the major ER functions is cotranslational transport and processing of secretory, lysosomal, and transmembrane proteins. Impaired protein processing caused by disturbances in the ER homeostasis results in the ER stress. Restoration of normal ER functioning requires activation of an adaptive mechanism involving cell response to misfolded proteins, the so-called unfolded protein response (UPR). Besides controlling protein folding, UPR plays a key role in other physiological processes, in particular, differentiation of cells of connective, muscle, epithelial, and neural tissues. Cell differentiation is induced by the physiological levels of ER stress, while excessive ER stress suppresses differentiation and can result in cell death. So far, it remains unknown whether UPR activation induces cell differentiation or if UPR is initiated by the upregulated synthesis of secretory proteins during cell differentiation. Cell differentiation is an important stage in the development of multicellular organisms and is tightly controlled. Suppression or excessive activation of this process can lead to the development of various pathologies in an organism. In particular, impairments in the differentiation of connective tissue cells can result in the development of fibrosis, obesity, and osteoporosis. Recently, special attention has been paid to fibrosis as one of the major complications of COVID-19. Therefore, studying the role of UPR in the activation of cell differentiation is of both theoretical and practical interest, as it might result in the identification of molecular targets for selective regulation of cell differentiation stages and as well as the potential to modulate the mechanisms involved in the development of various pathological states.

Antifibrotic Mechanism of Piceatannol in Bleomycin-Induced Pulmonary Fibrosis in Mice.

Background: Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal interstitial lung disease characterized by myofibroblast accumulation and extracellular matrix deposition, which lead to irreversible damage of the lung's architecture and the formation of fibrotic lesions. IPF is also a sequela in serious patients with the coronavirus disease 2019 (COVID-19). The molecular mechanisms under pulmonary fibrosis remain unclear, and there is no satisfactory treatment currently available. Piceatannol (PIC) is a naturally occurring resveratrol analog found in a variety of dietary sources such as grapes, passion fruit, and white tea. It has been reported to inhibit liver fibroblast growth and exhibited various antitumor activities, although its role in pulmonary fibrosis has not been established yet. In the present study, we evaluated the anti-fibrotic role of PIC in bleomycin (BLM)-induced pulmonary fibrosis in mice. Methods: Mice with BLM-induced pulmonary fibrosis were treated with PIC, and fibrotic changes were measured by hematoxylin-eosin (H&E) staining and hydroxyproline assay. Luciferase assay, Western blot assay, histological analysis, and immunofluorescence staining were used to evaluate the effect of PIC on fibroblast activation and autophagy in mouse embryonic fibroblast cells (NIH-3T3) and human lung fibroblast cells (HFL1). The anti-fibrotic mechanisms of PIC were either confirmed in vivo. Results: Our results showed that PIC significantly alleviated the bleomycin-induced collagen deposition and myofibroblast accumulation. In vitro and in vivo studies indicated that PIC plays a role in activating autophagy in the process of anti-fibroblast activation. Further mechanism studies demonstrated that PIC can promote autophagy via inhibiting the TGF-ß1-Smad3/ERK/P38 signaling pathway, which leads to a decreased number of activated myofibroblasts. Conclusion: Our study demonstrated for the first time that PIC possesses the protective effects against bleomycin-induced pulmonary fibrosis due to the direct pulmonary protective effects which enhance the effect of autophagy in vitro and in vivo and finally leads to the decreased number of activated myofibroblasts. PIC may serve as a candidate compound for pulmonary fibrosis therapy and attenuates the sequelae of SARS-COV-2 pulmonary fibrosis.

Cellular and Molecular Mechanism of Pulmonary Fibrosis Post-COVID-19: Focus on Galectin-1, -3, -8, -9.

Pulmonary fibrosis is a consequence of the pathological accumulation of extracellular matrix (ECM), which finally leads to lung scarring. Although the pulmonary fibrogenesis is almost known, the last two years of the COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its post effects added new particularities which need to be explored. Many questions remain about how pulmonary fibrotic changes occur within the lungs of COVID-19 patients, and whether the changes will persist long term or are capable of resolving. This review brings together existing knowledge on both COVID-19 and pulmonary fibrosis, starting with the main key players in promoting pulmonary fibrosis, such as alveolar and endothelial cells, fibroblasts, lipofibroblasts, and macrophages. Further, we provide an overview of the main molecular mechanisms driving the fibrotic process in connection with Galactin-1, -3, -8, and -9, together with the currently approved and newly proposed clinical therapeutic solutions given for the treatment of fibrosis, based on their inhibition. The work underlines the particular pathways and processes that may be implicated in pulmonary fibrosis pathogenesis post-SARS-CoV-2 viral infection. The recent data suggest that galectin-1, -3, -8, and -9 could become valuable biomarkers for the diagnosis and prognosis of lung fibrosis post-COVID-19 and promising molecular targets for the development of new and original therapeutic tools to treat the disease.

Disulfiram Exerts Antifibrotic and Anti-Inflammatory Therapeutic Effects on Perimysial Orbital Fibroblasts in Graves' Orbitopathy.

Fibrosis of extraocular muscles (EOMs) is a marker of end-stage in Graves' orbitopathy (GO). To determine the antifibrotic and anti-inflammatory therapeutic effects and the underlying molecular mechanisms of disulfiram (DSF) on perimysial orbital fibroblasts (pOFs) in a GO model in vitro, primary cultures of pOFs from eight patients with GO and six subjects without GO (NG) were established. CCK-8 and EdU assays, IF, qPCR, WB, three-dimensional collagen gel contraction assays, cell scratch experiments, and ELISAs were performed. After TGF-ß1 stimulation of pOFs, the proliferation rate of the GO group but not the NG group increased significantly. DSF dose-dependently inhibited the proliferation, contraction, and migration of pOFs in the GO group. Additionally, DSF dose-dependently inhibited fibrosis and extracellular matrix production markers (FN1, COL1A1, α-SMA, CTGF) at the mRNA and protein levels. Furthermore, DSF mediates antifibrotic effects on GO pOFs partially through the ERK-Snail signaling pathway. In addition, DSF attenuated HA production and suppressed inflammatory chemokine molecule expression induced by TGF-ß1 in GO pOFs. In this in vitro study, we demonstrate the inhibitory effect of DSF on pOFs fibrosis in GO, HA production, and inflammation. DSF may be a potential drug candidate for preventing and treating tissue fibrosis in GO.

Cardiac inflammation in COVID-19: Lessons from heart failure.

Cardiovascular disease (CVD) is the most common co-morbidity associated with COVID-19 and the fatality rate in COVID-19 patients with CVD is higher compared to other comorbidities, such as hypertension and diabetes. Preliminary data suggest that COVID-19 may also cause or worsen cardiac injury in infected patients through multiple mechanisms such as 'cytokine storm', endotheliosis, thrombosis, lymphocytopenia etc. Autopsies of COVID-19 patients reveal an infiltration of inflammatory mononuclear cells in the myocardium, confirming the role of the immune system in mediating cardiovascular damage in response to COVID-19 infection and also suggesting potential causal mechanisms for the development of new cardiac pathologies and/or exacerbation of underlying CVDs in infected patients. In this review, we discuss the potential underlying molecular mechanisms that drive COVID-19-mediated cardiac damage, as well as the short term and expected long-term cardiovascular ramifications of COVID-19 infection in patients.