The clinical characteristics of subcutaneous and mediastinal emphysema in anti-melanoma differentiation-associated 5 positive dermatomyositis associated with interstitial lung disease.

OBJECTIVES: To investigate the clinical characteristics of subcutaneous emphysema (SE) and mediastinal emphysema (ME) occurring in patients with anti-melanoma differentiation-associated gene 5 antibody-positive dermatomyositis associated with interstitial lung disease (anti-MDA5-positive DM-ILD). METHODS: In this retrospective study, a total of 117 anti-MDA5-positive DM-ILD patients were admitted to our hospital. All patients underwent an assessment of autoantibodies, serum ferritin levels, and lung high-resolution CT scans. RESULTS: In patients with anti-MDA5-positive DM-ILD, the incidence of SE/ME was found to be 11.1%, which was significantly higher compared to patients with anti-synthetase syndrome (p<0.01). The mortality rate among anti-MDA5-positive DM-ILD patients with SE/ME was significantly higher than those without SE/ME (p=0.0022). There was no statistically significant difference in the occurrence of SE/ME between patients with positive anti-Ro-52 antibodies and those with negative anti-Ro-52 antibodies (p=0.18). Patients with higher serum ferritin levels (1000 ng/ml ≤serum ferritin ≤1500 ng/ml) had a higher likelihood of developing SE/ME compared to patients with lower serum ferritin levels (serum ferritin <500 ng/ml) (p<0.01). Among 13 anti-MDA5-positive DM-ILD patients with SE/ME, six (46.2%) developed SE/ME within 1 month of being diagnosed and 53.8% of patients underwent positive pressure ventilation prior to the onset of SE/ME. CONCLUSIONS: We found that SE/ME is not uncommon in anti-MDA5-positive DM-ILD and is an important factor associated with poor patient prognosis. The occurrence of SE/ME is correlated with high levels of serum ferritin and is not related to anti-Ro-52 antibodies. Rheumatologists should pay close attention to SE/ME caused by positive pressure ventilation in anti-MDA5-positive DM-ILD patients.

Ang-(1-7)/Mas axis ameliorates bleomycin-induced pulmonary fibrosis in mice via restoration of Nox4-Nrf2 redox homeostasis.

Pulmonary fibrosis (PF) is a chronic, progressive interstitial lung disease characterized by diffuse alveolar inflammation, fibroblast differentiation, and the excessive deposition of extracellular matrix. During the progression of PF, redox imbalance caused by excessive reactive oxygen species (ROS) production can result in further destruction of lung tissue. At present, data on the role of NADPH oxidase-4 (Nox4)-nuclear factor erythroid 2-related factor 2 (Nrf2) redox imbalance in PF are limited. The angiotensin (1-7) [Ang-(1-7)]/Mas axis is a protective axis in the renin-angiotensin system (RAS) that exerts antifibrotic effects. Therefore, this study aimed to investigate the role of the Ang-(1-7)/Mas axis in PF and to explore its mechanism in depth. The results revealed that the Ang-(1-7)/Mas axis inhibited TGF-ß1-induced lung fibroblast differentiation, inflammation and fibrosis in bleomycin (BLM)-treated lung tissue. A mechanistic study suggested that the Ang-(1-7)/Mas axis may restore Nox4-Nrf2 redox homeostasis by upregulating the level of p62, reducing oxidative stress and the inflammatory response and thus delaying the progression of lung fibrosis. This study provides a theoretical basis for exploring the mechanisms of PF and therapeutic targets for PF.