Project description:A viral infection involves entry and replication of viral nucleic acid in a host organism, subsequently leading to biochemical and structural alterations in the host cell. In the case of SARS-CoV-2 viral infection, over-activation of the host immune system may lead to lung damage. Albeit the regeneration and fibrotic repair processes being the two protective host responses, prolonged injury may lead to excessive fibrosis, a pathological state that can result in lung collapse. In this review, we discuss regeneration and fibrosis processes in response to SARS-CoV-2 and provide our viewpoint on the triggering of alveolar regeneration in coronavirus disease 2019 (COVID-19) patients.
Project description:Adult PAP patients experience similar #COVID19 rates to the general population, and high rates of hospitalisation and deaths, underscoring their vulnerability and the need for measures to prevent infection. The impact of iGM-CSF must be considered. https://bit.ly/3M0wKnZ.
Project description:A 67-year-old male, with a history of severe COVID-19 infection and exposure to talc was seen for worsening shortness of breath for months, requiring supplemental oxygen. He was treated for COVID-19 infection and suspected pneumonia with no improvement. His pulmonary function test (PFT) worsened and computed tomography (CT) showing bilateral airspace opacities with ground-glass opacities (GGO), also worsened over time. He underwent bronchoscopy, bronchoalveolar lavage and pathology revealed pulmonary alveolar proteinosis (PAP). He subsequently underwent whole lung lavage (WLL) which significantly improved his crazy paving pattern on CT and was successfully weaned off supplemental oxygen.
Project description:Idiopathic pulmonary fibrosis (IPF) consists of fibrotic alveolar remodeling and progressive loss of pulmonary function. Genetic and experimental evidence indicates that chronic alveolar injury and failure to properly repair the respiratory epithelium are intrinsic to IPF pathogenesis. Loss of alveolar type 2 (AT2) stem cells or mutations that either impair their self-renewal and/or impair their differentiation into AT1 cells can serve as a trigger of pulmonary fibrosis. Recent reports indicate increased YAP activity in respiratory epithelial cells in IPF lungs. Individual IPF epithelial cells with aberrant YAP activation in bronchiolized regions frequently co-express AT1, AT2, conducting airway selective markers and even mesenchymal or EMT markers, demonstrating 'indeterminate' states of differentiation and suggesting that aberrant YAP signaling might promote pulmonary fibrosis. Yet, Yap and Taz have recently also been shown to be important for AT1 cell maintenance and alveolar epithelial regeneration after Streptococcus pneumoniae-induced injury. To investigate how epithelial Yap/Taz might promote pulmonary fibrosis or drive alveolar epithelial regeneration, we inactivated the Hippo pathway in AT2 stem cells resulting in increased nuclear Yap/Taz, and found that this promotes their alveolar regenerative capacity and reduces pulmonary fibrosis following bleomycin injury by pushing them along the AT1 cell lineage. Vice versa, inactivation of both Yap1 and Wwtr1 (encoding Taz) or Wwtr1 alone in AT2 cell stem cells impaired alveolar epithelial regeneration and resulted in increased pulmonary fibrosis upon bleomycin injury. Interestingly, the inactivation of only Yap1 in AT2 stem cells promoted alveolar epithelial regeneration and reduced pulmonary fibrosis. Together, these data suggest that epithelial Yap promotes, and epithelial Taz reduces pulmonary fibrosis suggesting that targeting Yap but not Taz-mediated transcription might help promote AT1 cell regeneration and treat pulmonary fibrosis.
Project description:Lung transplant recipients are at higher risk of developing COVID-19 infection compared to other solid organ transplants. The risk further increases in the unvaccinated patients. We present a case of a 43-year-old male who underwent bilateral sequential lung transplantation for pulmonary alveolar microlithiasis (PAM) and had an uneventful recovery. However, two years post-transplantation, the patient developed chronic lung allograft dysfunction (CLAD) with bronchiolitis obliterans syndrome and two episodes of COVID-19 infection. During the second episode of COVID-19 infection, the patient developed sepsis and multi-organ dysfunction ultimately resulting in death. Our case report highlights the increased susceptibility of PAM patients' post-lung transplant to COVID-19 infection. Continuous follow-up of PAM patients' post-lung transplantation is necessary to prevent unfavorable outcomes.
Project description:Dexamethasone improves the survival of COVID-19 patients in need of supplemental oxygen therapy. Hospitalized COVID-19 patients eligible for dexamethasone therapy were recruited from the general care ward in several centers in Greece and the Netherlands and whole blood transcriptomic analysis was performed before and after starting dexamethasone treatment. Peripheral blood mononuclear cells (PBMCs) were isolated from healthy individuals and COVID-19 patients and stimulated with inactivated SARS-CoV-2 ex vivo in the presence or absence of dexamethasone and their transcriptome was assessed.
Project description:Stem cells undergo dynamic changes in response to injury to regenerate lost cells. However, the identity of transitional states and the mechanisms that drive their trajectories remain understudied. Using lung organoids, multiple in vivo repair models, single-cell transcriptomics and lineage tracing, we find that alveolar type-2 epithelial cells undergoing differentiation into type-1 cells acquire pre-alveolar type-1 transitional cell state (PATS) en route to terminal maturation. Transitional cells undergo extensive stretching during differentiation, making them vulnerable to DNA damage. Cells in the PATS show an enrichment of TP53, TGFβ, DNA-damage-response signalling and cellular senescence. Gain and loss of function as well as genomic binding assays revealed a direct transcriptional control of PATS by TP53 signalling. Notably, accumulation of PATS-like cells in human fibrotic lungs was observed, suggesting persistence of the transitional state in fibrosis. Our study thus implicates a transient state associated with senescence in normal epithelial tissue repair and its abnormal persistence in disease conditions.