Daily Ards Research Analysis

Acute respiratory distress syndrome (ARDS) has emerged as a significant global health challenge, with no definitive curative treatment available. Recent evidence suggests that pyroptosis of immune cells plays a pivotal role in the pathogenesis of ARDS. Targeting and modulating immune cell pyroptosis in lung tissue may offer a promising strategy to mitigate the harmful inflammation associated with this condition. In this study, we designed and synthesized a novel class of peptide-functionalized nanoparticles, PV-K, which possess an intrinsic capacity for phagocytosis by macrophages. Concurrently, the incorporation of two FFD functional groups into a single polypeptide enhances the biological activity of PV-K. Amazingly, PV-K demonstrated potent inhibitory effects on nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing protein 3 (NLRP3)-mediated pyroptosis in both mouse bone marrow-derived macrophages and the human THP-1 cell-derived macrophages. In both lipopolysaccharide and cecal ligation and puncture induced acute lung injury mouse models, treatment with PV-K significantly reduced disease severity by alleviating pulmonary inflammation and inhibiting macrophage pyroptosis. Transcriptomic analysis revealed that PV-K enhanced SQSM1/p62-mediated autophagy through upregulation of the NRF2 signaling pathway. Mechanistically, PV-K facilitated the interaction between SQSTM1/p62 and NLRP3, promoting the autolysosomal degradation of NLRP3. Notably, the inhibitory effect of PV-K on macrophage pyroptosis during acute lung injury was abrogated in Nrf2

BACKGROUND: Platelet-activating factor (PAF)-induced pulmonary endothelial barrier failure is mediated by acid sphingomyelinase (ASM) translocation to caveolae. ASM, however, lacks a transmembrane domain for anchoring inside caveolae. We hypothesised that ASM anchors to cation-independent mannose-6-phosphate (M6P) receptor (CI-M6PR) in caveolae, from where it can be competitively released by M6P. METHODS: We explored ASM-CI-M6PR interactions using co-immunoprecipitation and proximity ligation assay in isolated lungs and human pulmonary microvascular endothelial cells. ASM release by M6P was determined in human pulmonary microvascular endothelial cells, isolated lungs and RESULTS: Co-immunoprecipitation and proximity ligation assay revealed an ASM interaction with CI-M6PR in endothelial caveolae, which was further increased by PAF. M6P, but not glucose-6-phosphate, caused ASM release, thereby decreasing ASM content and activity in caveolae CONCLUSIONS: CI-M6PR anchors ASM in caveolae. M6P may hence present a promising target in ASM-related lung injury and oedema.

INTRODUCTION: The extent of in vivo damage to the alveolar-capillary membrane in patients with primary lung injury remains unclear. In cases of ARDS related to COVID-19 and Influenza type A, the complexity of the damage increases further, as viral pneumonia cannot currently be treated with a causal approach. AIMS OF THE STUDY: Our primary goal is to enhance the understanding of Acute Respiratory Distress Syndrome (ARDS) by demonstrating damage to the alveocapillary membrane in critically ill patients with COVID-19 and influenza type A. We will achieve this by measuring the levels of proteins and albumin in bronchoalveolar fluid (BAL) and serum. Our secondary objective is to assess patient outcomes related to elevated protein and albumin levels in both BAL and blood serum, which will deepen our understanding of this complex condition. MATERIALS AND METHODS: Bronchoalveolar lavage (BAL) fluid and serum samples were meticulously collected from a total of 64 patients, categorized into three distinct groups: 30 patients diagnosed with COVID-19-related acute respiratory distress syndrome (ARDS), 14 patients with influenza type A (H1N1 strain), also experiencing ARDS, and a control group consisting of 20 patients who were preoperatively prepared for elective surgical procedures without any diagnosed lung disease. The careful selection and categorization of patients ensure the robustness of our study. BAL samples were taken within the first 24 hours following the commencement of invasive mechanical ventilation in the intensive care unit, alongside measurements of serum albumin levels. In the control group, BAL and serum samples were collected after the induction of general endotracheal anaesthesia. RESULTS: Patients in the COVID-19 group are significantly older than those in the Influenza type A (H1N1) group, with median ages of 72.5 years and 62 years, respectively (p < 0.01, Mann-Whitney U test). Furthermore, serum albumin levels (measured in g/L) revealed significant differences across all three groups in the overall sample, yielding a p-value of less than 0.01 according to ANOVA. In terms of treatment outcomes, serum albumin levels also exhibited a significant correlation, with a p-value of 0.03 (Mann-Whitney U test). A reduction in serum albumin levels (below 35 g/L), combined with elevated protein levels in bronchoalveolar lavage (BAL), serves as a predictor of poor outcomes in patients with acute respiratory distress syndrome (ARDS), as indicated by a p-value of less than 0.01 (ANOVA). CONCLUSIONS: Our findings indicate that protein and albumin levels in bronchoalveolar lavage (BAL) fluid are elevated in severe acute respiratory distress syndrome (ARDS) cases. This suggests that BAL can effectively evaluate protein levels and fractions, which could significantly assist in assessing damage to the alveolocapillary membrane. Additionally, the increased albumin levels in BAL, often accompanied by a decrease in serum albumin levels, may serve as a valuable indicator of compromised integrity of the alveolar-capillary membrane in ARDS, with potential implications for patient care.