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Rationale: Fibrotic hypersensitivity pneumonitis (FHP) is a debilitating interstitial lung disease driven by incompletely understood immune mechanisms. Objectives: To elucidate immune aberrations in FHP in single-cell resolution. Methods: Single-cell 5′ RNA sequencing was conducted on peripheral blood mononuclear cells and BAL cells obtained from 45 patients with FHP, 63 patients with idiopathic pulmonary fibrosis (IPF), 4 patients with nonfibrotic hypersensitivity pneumonitis, and 36 healthy control subjects in the United States and Mexico. Analyses included differential gene expression (Seurat), TF (transcription factor) activity imputation (DoRothEA-VIPER), and trajectory analyses (Monocle3 and Velocyto-scVelo-CellRank). Measurements and Main Results: Overall, 501,534 peripheral blood mononuclear cells from 110 patients and control subjects and 88,336 BAL cells from 19 patients were profiled. Compared with control samples, FHP has elevated classical monocytes (adjusted-P = 2.5 × 10−3) and is enriched in CCL3hi/CCL4hi and S100Ahi classical monocytes (adjusted-P < 2.2 × 10−16). Trajectory analyses demonstrate that S100Ahi classical monocytes differentiate into SPP1hi lung macrophages associated with fibrosis. Compared with both control subjects and IPF, cells from patients with FHP are significantly enriched in GZMhi cytotoxic T cells. These cells exhibit TF activities indicative of TGFβ and TNFα and NFκB pathways. These results are publicly available at . Conclusions: Single-cell transcriptomics of patients with FHP uncovered novel immune perturbations, including previously undescribed increases in GZMhi cytotoxic CD4+ and CD8+ T cells—reflecting this disease's unique inflammatory T cell–driven nature—as well as increased S100Ahi and CCL3hi/CCL4hi classical monocytes also observed in IPF. Both cell populations may guide the development of new biomarkers and therapeutic interventions. [ABSTRACT FROM AUTHOR]

Background: Persistent respiratory symptoms and lung abnormalities post‐COVID‐19 are public health problems. This study evaluated biomarkers to stratify high‐risk patients to the development or persistence of post‐COVID‐19 interstitial lung disease. Methods: One hundred eighteen patients discharged with residual lung abnormalities compatible with interstitial lung disease (COVID‐ILD patients) after a severe COVID‐19 were followed for 1 year (post‐COVID‐ILD patients). Physical examination, pulmonary function tests, and chest high‐resolution computed tomography (HRCT) were performed. Soluble forms (s) of PD‐L1, PD‐L2, TIM‐3, and GAL‐9 were evaluated in serum and cell culture supernatant, as well as T‐cells subsets and the transmembrane expression of PD‐L1 and PD‐L2 on the cell surface. Results: Eighty percent of the post‐COVID‐ILD patients normalized their lung function at 1‐year follow‐up, 8% presented COVID‐independent ILD, and 12% still showed functional and HRCT alterations. PD‐L2 levels were heterogeneous during acute COVID‐19 (aCOVID); patients who increased (at least 30%) their sPD‐L2 levels at 1 year post‐COVID‐19 and exhibited altered CD4/CD8 ratio showed persistence of chest tomographic and functional alterations. By contrast, patients who decreased sPD‐L2 displayed a complete lung recovery. sPD‐L1, sTIM‐3, and sGAL‐9 increased significantly during aCOVID and decreased in all patients after 1‐year follow‐up. Conclusion: Increased sPD‐L2 and an altered CD4/CD8 ratio after 12 months of aCOVID are associated with the persistence of lung lesions, suggesting that they may contribute to lung damage post‐COVID‐19. [ABSTRACT FROM AUTHOR]

Rheumatoid arthritis (RA) is an autoimmune disease mainly characterized by joint inflammation. It presents extra-articular manifestations, with the lungs being one of the affected areas. Among these, damage to the pulmonary interstitium (Interstitial Lung Disease—ILD) has been linked to proteins involved in the inflammatory process and related to extracellular matrix deposition and lung fibrosis establishment. Peptidyl arginine deiminase enzymes (PAD), which carry out protein citrullination, play a role in this context. A genetic association analysis was conducted on genes encoding two PAD isoforms: PAD2 and PAD4. This analysis also included ancestry informative markers and protein level determination in samples from patients with RA, RA-associated ILD, and clinically healthy controls. Significant single nucleotide variants (SNV) and one haplotype were identified as susceptibility factors for RA-ILD development. Elevated levels of PAD4 were found in RA-ILD cases, while PADI2 showed an association with RA susceptibility. This work presents data obtained from previously published research. Population variability has been noticed in genetic association studies. We present data for 14 SNVs that show geographical and genetic variation across the Mexican population, which provides highly informative content and greater intrapopulation genetic diversity. Further investigations in the field should be considered in addition to AIMs. The data presented in this study were analyzed in association with SNV genotypes in PADI2 and PADI4 to assess susceptibility to ILD in RA, as well as with changes in PAD2 and PAD4 protein levels according to carrier genotype, in addition to the use of covariates such as ancestry markers. Dataset: DOI 10.3390/cells12182235 (published manuscript.). The datasets generated for this study can be found in ClinVar accessions SCV001422427–SCV001422434. Dataset License: Attribution 4.0 International (CC BY 4.0) [ABSTRACT FROM AUTHOR]

In COVID-19, critical disease and invasive mechanical ventilation (IMV) increase the risk of death, mainly in patients over 60 years of age. Objectives: To find the relationship between miR-21-5p and miR-146a-5p in terms of the severity, IMV, and mortality in hospitalized COVID-19 patients younger than 55 years of age. Methods: The patients were stratified according to disease severity using the IDSA/WHO criteria for severe and critical COVID-19 and subclassified into critical non-survivors and critical survivors. Results: Ninety-seven severe/critical COVID-19 patients were included; 81.3% of the deceased were male and 18.8% were female. Higher expression miR-21-5p levels were associated as follows: severe vs. critical disease (p = 0.007, FC = 0.498), PaO2/FiO2 index, mild vs. severe (p = 0.027, FC = 0.558), and survivors vs. non-survivors (p = 0.03, FC = 0.463). Moreover, we identified correlations with clinical variables: CRP (rho = −0.54, p < 0.001), D-dimer (rho = −0.47, p < 0.05), related to damage in the kidney (rho = 0.60, p < 0.001), liver (rho = 0.41, p < 0.05), and lung (rho = 0.54, p < 0.001). Finally, miR-21-5p thresholds were calculated according to severity (8.191), IMV (8.191), and mortality (8.237); these values increased the risk of developing a critical disease (OR = 4.19), the need for IMV (OR = 5.63), and death (OR = 6.00). Conclusion: Increased expression levels of miR-21-5p are related to worse outcome of COVID-19 in younger hospitalized patients. [ABSTRACT FROM AUTHOR]

Introduction Surfactant protein D (SP-D) plays an important role in the innate responses against pathogens and its production is altered in lung disorders. Methods We studied the circulating levels of SP-D in 37 patients with acute respiratory distress syndrome due to the A/H1N1 virus infection and in 40 healthy controls. Cox logistic regression models were constructed to explore the association of SP-D levels and risk of death. Results Mortality rate after a 28-day was 32.42%. Significant higher levels of SP-D were detected in A/H1N1 patients with fatal outcome (p < 0.05). After adjusting for confounding variables, levels of SP-D ≥ 250 ng/mL were associated with increased the risk of death (HR = 8.27, 95% CI 1.1-64.1, p = 0.043). Conclusions Our results revealed that higher circulating levels of SP-D are associated with higher mortality risk in critically ill A/H1N1 patients. SP-D might be a predictive factor of poor outcomes in viral pneumonia. Keywords Surfactant protein D (SP-D) * A/H1N1 virus * Influenza * ARDS * Mortality * Biomarker, Introduction Host factors including cardiac, respiratory, and metabolic comorbidities are associated with poorer outcomes of A/H1NI infection and development of acute respiratory distress syndrome (ARDS) [1-3]. Recent studies support the [...]