Biology subjects

D'Armiento, J. M.

Publications and source records attributed to D'Armiento, J. M..

2 recordsLinked to original sources

bioRxiv2021

Dysregulated myogenesis and autophagy in genetically induced pulmonary emphysema

Patients with chronic obstructive pulmonary disease (COPD)-pulmonary emphysema often develop locomotor muscle dysfunction, which is independently associated with disability and higher mortality in that population. Muscle dysfunction entails reduced muscle mass and force-generation capacity, which are influenced by fibers integrity. Myogenesis, which is muscle turnover driven by progenitor cells such as satellite cells, contributes to the maintenance of muscle integrity in the context of organ development and injury-repair cycles. Injurious events crucially occur in COPD patients skeletal muscles in the setting of exacerbations and infections which lead to acute decompensations for limited periods of time after which, patients typically fail to recover the baseline status they had before the acute event. Autophagy, which is dysregulated in muscles from COPD patients, is a key regulator of satellite cells activation and myogenesis, yet very little research has so far investigated the mechanistic role of autophagy dysregulation in COPD muscles. Using a genetically inducible murine model of COPD-driven muscle dysfunction and confirmed with a second genetic animal model, we found a significant myogenic dysfunction associated with a reduced proliferative capacity of freshly isolated satellite cells. Transplantation experiments followed by lineage tracing suggest that an intrinsic defect in satellite cells, and not in the COPD environment, plays a dominant role in the observed myogenic dysfunction. RNA sequencing analysis of freshly isolated satellite cells suggests dysregulation of transcripts associated with control of cell cycle and autophagy, which is confirmed by a direct observation of COPD mice satellite cells fluorescent-tracked autophagosome formation. Moreover, spermidine-induced autophagy stimulation leads to improved satellite cells autophagosome turnover, replication rate and myogenesis. Our data suggests that pulmonary emphysema causes a disrupted myogenesis, which could be improved with stimulation of autophagy and satellite cells activation, leading to an attenuated muscle dysfunction in this context.

physiology↗

bioRxiv2019

Alpha-1 Antitrypsin Antisense Oligonucleotide Modulates Protease-Antiprotease Imbalance without Further Aggravating Smoke-induced Lung Injury

Alpha-1 antitrypsin (AAT) is a serum protease inhibitor that prevents lung injury from protease production during cigarette smoking but causes severe liver disease once mutated. A custom AAT antisense oligonucleotide (ASO) was found to be beneficial for the AATD liver disease by blocking the mutated AAT transcripts. Here we hypothesized that knock-down of AAT aggravates murine lung injury during smoke exposure and acute exacerbations of chronic obstructive pulmonary disease (COPD). C57BL/6J mice were randomly divided into 4 groups for each of the injury models, smoking (inhale for 3 months at 150mg/m3) and smoke-flu (inhale for 2 weeks and intranasal influenza virus). The ASO and control (No-ASO) were injected subcutaneously at 10ml/kg of body weight, starting with smoking or four days prior to influenza infection weekly at 50mg/kg. ASO treatment during a 3 month smoke exposure significantly increased the expression of Cela1 mRNA and decreased the serum and lung AAT expression. However, despite the decrease in AAT, neither the inflammatory cell counts in the bronchoalveolar lavage fluid (BALF) nor the lung structural changes were significantly affected by ASO treatment. We observed significant differences in inflammation and emphysema due to smoke exposure alone. With the smoke-flu model, similarly the major differences were found between smoke-flu and room air control, with no additional effect with ASO treatment. Off-target effects or compensatory mechanisms may account for this finding. Alternatively, the reduction of AAT with ASO treatment was not robust enough to lead to lung injury. The result also suggest that the AAT ASO approach for treating liver disease is relatively safe at the specified dose as it did not lead to detrimental outcomes in the lung. These potential mechanisms need to be further investigated in order to fully understand the impact of AAT inhibition on protease-antiprotease imbalance in the murine smoke exposure model.

physiology↗