Two anti-fibrotic drugs, pirfenidone (PFD) and nintedanib (NTD), are currently used to treat idiopathic pulmonary fibrosis (IPF). Peripheral blood mononuclear cells (PBMCs) are immunocompetent cells that could orchestrate cell–cell interactions associated with IPF pathogenesis. We employed RNA sequencing to examine the transcriptome signature in the bulk PBMCs of patients with IPF and the effects of anti-fibrotic drugs on these signatures. Differentially expressed genes (DEGs) between “patients with IPF and healthy controls” and “before and after anti-fibrotic treatment” were analyzed. Enrichment analysis suggested that fatty acid elongation interferes with TGF-β/Smad signaling and the production of oxidative stress since treatment with NTD upregulates the fatty acid elongation enzymes ELOVL6. Treatment with PFD downregulates COL1A1, which produces wound-healing collagens because activated monocyte-derived macrophages participate in the production of collagen, type I, and alpha 1 during tissue damage. Plasminogen activator inhibitor-1 (PAI-1) regulates wound healing by inhibiting plasmin-mediated matrix metalloproteinase activation, and the inhibition of PAI-1 activity attenuates lung fibrosis. DEG analysis suggested that both the PFD and NTD upregulate SERPINE1, which regulates PAI-1 activity. This study embraces a novel approach by using RNA sequencing to examine PBMCs in IPF, potentially revealing systemic biomarkers or pathways that could be targeted for therapy.

Non-emphysematous chronic obstructive pulmonary disease (COPD), which is defined based on chest computed tomography findings, presented different transcriptome features of peripheral blood mononuclear cells (PBMCs) compared with emphysematous COPD. Enrichment analysis of transcriptomic data in COPD demonstrated that the “Hematopoietic cell lineage” pathway in Kyoto Encyclopedia of Genes and Genomes pathway analysis was highly upregulated, suggesting that cellular dynamic dysregulation in COPD lungs is affected by pathologically modified PBMCs. The differentially expressed genes (DEGs) upregulated in PBMCs reflected the disease state of non-emphysematous COPD. Upregulated DEGs such as XCL1, PRKCZ, TMEM102, CD200R1, and AQP1 activate T lymphocytes and eosinophils. Upregulating keratan sulfate biosynthesis and metabolic processes is associated with protection against the destruction of the distal airways. ITGA3 upregulation augments interactions with extracellular matrix proteins, and COL6A1 augments the profibrotic mast cell phenotype during alveolar collagen VI deposition. Upregulating HSPG2, PDGFRB, and PAK4 contributes to the thickening of the airway wall, and upregulating SERPINF1 expression explains the better-preserved vascular bed. Therefore, gene expression and pathway analysis in PBMCs in patients with non-emphysematous COPD represented type 2 immune responses and airway remodeling features. Therefore, these patients have asthmatic potential despite no clinical signs of asthma, in contrast to those with emphysematous COPD.

Background: Sarcoidosis is a systemic granulomatous disease of unknown etiology. Pulmonary sarcoidosis with extrapulmonary lesions (EPL) confers poor prognoses. The transcriptomic features of peripheral blood mononuclear cells (PBMCs) could be crucial in sarcoidosis pathogenesis. However, the gene expression characteristics associated with EPL development remain unknown. Methods: Bulk PBMCs were collected from 26 healthy controls and 14 patients with pulmonary sarcoidosis stratified into those with (n = 9) or without (n = 5) EPL. None of the participants were receiving immunosuppressive agents. PBMC transcriptomic analysis was conducted using RNA sequencing. Results: Principal component analysis (PCA) revealed a clear distinction between pulmonary sarcoidosis and healthy control groups, with 227 differentially expressed genes (88 upregulated, 139 downregulated), including upregulated (CLEC7A, GBP5, JAK2, IL15, IL1B, CXCL8, and CXCL10) and downregulated (TNFRSF13C, CD40LG, CD28, and ID3) genes in pulmonary sarcoidosis group. Enrichment analysis revealed upregulated immunological pathways related to granuloma formation in pulmonary sarcoidosis PBMCs, including T helper 17 and tumor necrosis factor-alpha signaling pathways, IL-1B, IL-6, and IL-17 production, and response to external stimuli. Furthermore, patients with and without EPL showed 206 differentially expressed genes (131 upregulated, 75 downregulated), including upregulated (IFNG and IFNLR1) and downregulated (SOCS3, MMP9, and CXCL10) genes. Gene ontology (GO) analysis revealed that interleukin 6 (IL-6) and IL-23 production were upregulated in patients with EPL. Conclusions: These findings elucidate the mechanisms underlying granuloma formation in sarcoidosis and demonstrate the differential transcriptomic features of PBMCs in patients with and without EPL. The upregulation of IFNG and IFNLR1 may be related to EPL development and could serve as potential therapeutic targets for sarcoidosis.

Background: While immune checkpoint inhibitor (ICI)-related pneumonitis (CIP) may relapse during or after steroid treatment, clinical factors associated with CIP relapse are unclear. This study explored risk factors potentially associated with CIP relapse. Methods: This single-center retrospective study included 1099 patients who received ICIs at our institution between April 2015 and March 2022. Among them, 39 patients who developed CIP and were treated with systemic steroids and tapered to prednisolone (PSL) ≤ 20 mg/day were analyzed. Patients were classified into relapse and non-relapse groups based on whether CIP recurred during or after steroid treatment. Patient characteristics, clinical features at onset, and treatment strategies were compared between the two groups. Results: Thirteen patients (33.3%) experienced relapse. Compared with the non-relapse group, the relapse group had a significantly higher proportion of non-smokers (30.8 vs. 3.3%, p = 0.035), a greater frequency of Common Terminology Criteria for Adverse Events (CTCAE) Grade 2 pneumonitis (92.3 vs. 53.8%, p = 0.029), and lower serum KL-6 levels (288 vs. 704 U/mL, p = 0.014). The relapse group also had a shorter duration of steroid therapy at the initial dose, ≥0.5 mg/kg/day, ≥15 mg/day, and ≥20 mg/day (p < 0.05) and lower cumulative steroid doses (1140 vs. 1902 mg, p = 0.015). Relapse tended to occur in patients with relatively mild pneumonitis who received lower steroid doses and shorter treatment durations. Conclusions: Non-smoking status, CTCAE Grade 2 pneumonitis, lower serum KL-6 levels, shorter duration of steroid therapy, and lower cumulative steroid dose were potentially associated with CIP relapse. Adequate steroid dosing and tapering may help prevent relapse.