Idiopathic Pulmonary Fibrosis Research Articles

Timing impact on the initiation of pirfenidone therapy on idiopathic pulmonary fibrosis disease progression

In this editorial, we comment on the article by Lei et al, with a specific focus on the timing of the initiation of the antifibrotic agent pirfenidone (PFD) in the management of idiopathic pulmonary fibrosis (IPF) and its impact on lung function of IPF patients. PFD is an antifibrotic agent that is widely used in the management of IPF in both early and advanced stages. It inhibits various pathways and has antifibrotic, anti-inflammatory, and antioxidant properties. Despite dosage lowering, PFD slowed IPF progression and maintained functional capacity. The 6-min walk distance test indicated that patients tolerated adverse events well, and PFD significantly reduced the incidence of progression episodes and death. Even when a single disease-progression event occurred, continuing PFD treatment had benefits.

Identification of potential mechanisms of Schisandrin B in the treatment of idiopathic pulmonary fibrosis by integrating network pharmacology and experimental validation.

Idiopathic pulmonary fibrosis (IPF) is a worsening fibrotic condition characterized by a short survival rate and limited treatment options. This study evaluates the potential anti-fibrotic properties of Schisandrin B (Sch B) through network pharmacology and experimental validation. A mouse model of bleomycin-induced pulmonary fibrosis was established, and the modeled mice were treated with Sch B at three doses (20 mg/kg/day, 40 mg/kg/day, and 80 mg/kg/day). A fibrotic model was developed in NIH/3T3 cells by treating them with TGF-β (10 ng/mL) and administering Sch B at various concentrations (10, 20, and 40 µM). The results revealed that Sch B treatment delayed the development of bleomycin-induced pulmonary fibrosis and substantially decreased the transcription levels of collagen I and α-SMA in TGF-β-induced fibroblasts. Core targets were screened with protein-protein interaction network analysis, molecular complex detection (MCODE), and CytoHubba plugin. The application of Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, and molecular docking highlighted the significance of the HIF-1α signaling pathway in the potential mechanism of Sch B in IPF therapy. Western blot, PCR, and immunofluorescence were performed to validate the effects of Sch B on HIF-1α. In vivo and in vitro, Sch B administration reduced HIF-1α expression. These outcomes provide valuable insights into the potential mechanism by which Sch B delays IPF development, with HIF-1α potentially serving as a key target. However, further investigation is warranted to assess the safety and efficacy of Sch B in clinical settings.

Discovery of Selective PDE1 Inhibitors with Anti-pulmonary Fibrosis Effects by Targeting the Metal Pocket.

Idiopathic pulmonary fibrosis (IPF) is a fatal lung disease with no ideal drugs. Our previous research demonstrated that phosphodiesterase 1 (PDE1) could be a promising target for the treatment of IPF. However, only a few selective PDE1 inhibitors are available, and the mechanism of recognition between inhibitors and the PDE1 protein is not fully understood. This study carried out a step-by-step optimization of a dihydropyrimidine hit Z94555858. By targeting the metal pocket of PDE1, a lead compound 3f was obtained, exhibiting an IC50 value of 11 nM against PDE1, moderate selectivity over other PDEs, and significant anti-fibrotic effects in bleomycin-induced pulmonary fibrosis rats. The structure-activity relationship study aided by molecular docking revealed that forming halogen bonds with water in the metal pocket greatly enhanced the PDE1 inhibition, providing a novel strategy for further rational design of PDE1 inhibitors.

Combined therapy with pirfenidone and nintedanib counteracts fibrotic silicosis in mice.

Pneumoconiosis, especially silicosis, is a prevalent occupational disease with substantial global economic implications and lacks a definitive cure. Both pneumoconiosis and idiopathic pulmonary fibrosis (IPF) are interstitial lung diseases, which share many common physiological characteristics. Because pirfenidone and nintedanib are approved to treat IPF, their potential efficacy as antifibrotic agents in advanced silicosis deserves further exploration. Thus, we aimed to evaluate the individual and combined effects of pirfenidone and nintedanib in treating advanced silicosis mice and elucidate the underlying mechanisms of their therapeutic actions via multiomics. We administered monotherapy or combined therapy of pirfenidone and nintedanib, with low and high doses, in silicosis established after 6weeks and evaluated lung function, inflammatory responses and fibrotic status. Additionally, we employed transcriptomic and metabolomic analyses to uncover the mechanisms underlying different therapeutic strategies. Both pirfenidone and nintedanib were effective in treating advanced silicosis, with superior outcomes observed in combination therapy. Transcriptomic and metabolomic analyses revealed that pirfenidone and nintedanib primarily exerted their therapeutic effects by modulating immune responses, signalling cascades and metabolic processes involving lipids, nucleotides and carbohydrates. Furthermore, we experimentally validated both monotherapy and combined therapy yielded therapeutic benefits through two common signalling pathways: steroid biosynthesis and purine metabolism. In conclusion, pirfenidone and nintedanib, either individually or in combination, demonstrate substantial potential in advanced silicosis. Furthermore, combined therapy outperformed monotherapy, even at low doses. These therapeutic benefits are attributed to their influence on diverse signalling pathways and metabolic processes.

Nintedanib attenuates NLRP3 inflammasome-driven liver fibrosis by targeting Src signaling.

Liver injury induces an inflammatory response that activates hepatic stellate cells, which is the initial factor of liver fibrosis. Nintedanib, a multi-targeted tyrosine kinase inhibitor targeting the Src signalling pathway, has been approved for the treatment of idiopathic pulmonary fibrosis. However, it is still not known whether nintedanib ameliorates liver fibrosis by inhibiting inflammasome activation. Here, a carbon tetrachloride (CCl4)-induced liver fibrosis model was used to assess the anti-fibrotic efficacy of nintedanib in vivo. Lipopolysaccharide and ATP were used to activate nucleotide oligomerisation domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasomes in LX-2 cells, and the efficacy of nintedanib on NLRP3 inflammasome activation was evaluated. Moreover, we used Src-overexpressing and Src-downregulating lentiviruses to transfect LX-2 cells to explore the targets of nintedanib. Nintedanib attenuated inflammation and extracellular matrix accumulation in CCl4-induced fibrotic livers and reduced the expression of NLRP3, fibrotic makers, and the phosphorylation of Src, epidermal growth factor receptor (EGFR), AKT, ERK1/2 in LX-2 cells. Furthermore, nintedanib thwarted NLRP3 inflammasome activation by suppressing the phosphorylation of Src and its downstream signalling pathway and reducing reactive oxygen species production. Our study indicates that nintedanib effectively suppresses NLRP3 inflammasome activation and has the potential for the treatment of liver fibrosis.

Air Pollution and Interstitial Lung Disease.

This review article explores the multifaceted relationship between air pollution and interstitial lung diseases (ILDs), particularly focusing on idiopathic pulmonary fibrosis (IPF), the most severe form of fibrotic ILD. Air pollutants are mainly composed of particulate matter (PM), ozone (O3), nitrogen dioxide (NO2), carbon monoxide (CO), and sulfur dioxide (SO2). They are recognized as risk factors for several respiratory diseases. However, their specific effects on ILDs and related mechanisms have not been thoroughly studied yet. Emerging evidence suggests that air pollutants may contribute to the development and acute exacerbation of ILDs. Longitudinal studies have indicated that air pollution can adversely affect the prognosis of disease by decreasing lung function and increasing mortality. Lots of in vitro, in vivo, and epidemiologic studies have proposed possible mechanisms linking ILDs to air pollution, including inflammation and oxidative stress induced by exposure to air pollutants, which may induce mitochondrial dysfunction, promote cellular senescence, and disrupt normal epithelial repair processes. Despite these findings, effective interventions to mitigate effects of air pollution on ILD are not well established yet. This review emphasizes the urgent need to address air pollution as a key environmental risk factor for ILDs and calls for further studies to clarify its effects and develop preventive and therapeutic strategies.

Could Hepcidin Be a New Biomarker in Patients with Idiopathic Pulmonary Fibrosis (IPF)?

Objectives: Hepcidin is a biomarker produced by hepatocytes in chronic disease anemia and is known to increase during chronic inflammation. This study compares the hepcidin levels in idiopathic pulmonary fibrosis (IPF) patients and controls, evaluating its relationship with anemia and systemic inflammation in IPF patients. Methods: This study included 82 IPF patients and 31 controls. Hepcidin levels were compared between the two groups. In the IPF group, the hepcidin and anemia parameters were compared between anemic and non-anemic patients. The significance between the hepcidin and systemic inflammation parameters such as Erythrocyte Sedimentation Rate, CRP (C-reactive protein) levels, ferritin levels, and the Systemic Immune–Inflammation Index (SII) was investigated. Erythrocyte Sedimentation Rate, C-reactive protein (CRP) levels, and ferritin levels were measured using automated analyzers. Hepcidin and erythropoietin (EPO) levels were determined using ELISA kits. Results: A significant difference in hepcidin levels was found between the IPF and control groups (37.13 ± 14.92 vs. 25.77 ± 11.25, p < 0.001). No significant difference in hepcidin levels was found between anemic and non-anemic IPF patients (38.25 ± 16.2 vs. 36.7 ± 14.6, p = 0.719). No significant correlation was found between hepcidin levels and anemia parameters (serum iron, ferritin, vitamin B12, serum transferrin, transferrin saturation, total iron-binding capacity, hemoglobin, folate, and erythropoietin) in IPF patients. Despite significant differences in the systemic inflammation parameters (ferritin and CRP) between patients and controls, no significant correlation was found between their hepcidin and systemic inflammation parameters. Conclusions: Our study demonstrates that the hepcidin levels in IPF patients are elevated independently of anemia and systemic inflammation. We propose that hepcidin could be a potential biomarker to be investigated in IPF patients.

The role of epithelial-mesenchymal transition in pulmonary fibrosis: lessons from idiopathic pulmonary fibrosis and COVID-19.

Despite the tremendous advancements in the knowledge of the pathophysiology and clinical aspects of SARS-CoV-2 infection, still many issues remain unanswered, especially in the long-term effects. Mounting evidence suggests that pulmonary fibrosis (PF) is one of the most severe complications associated with COVID-19. Therefore, understanding the molecular mechanisms behind its development is helpful to develop successful therapeutic strategies. Epithelial to mesenchymal transition (EMT) and its cell specific variants endothelial to mesenchymal transition (EndMT) and mesothelial to mesenchymal transition (MMT) are physio-pathologic cellular reprogramming processes induced by several infectious, inflammatory and biomechanical stimuli. Cells undergoing EMT acquire invasive, profibrogenic and proinflammatory activities by secreting several extracellular mediators. Their activity has been implicated in the pathogenesis of PF in a variety of lung disorders, including idiopathic pulmonary fibrosis (IPF) and COVID-19. Aim of this article is to provide an updated survey of the cellular and molecular mechanisms, with emphasis on EMT-related processes, implicated in the genesis of PF in IFP and COVID-19.

Long-Term Air Pollution Exposure and Severity of Idiopathic Pulmonary Fibrosis: Data from the IPF-PRO Registry.

While exposure to air pollution is a known risk factor for adverse pulmonary outcomes, its impact in individuals with idiopathic pulmonary fibrosis (IPF) is less well understood. To investigate the effects of long-term exposure to air pollution on disease severity and progression in patients with IPF and to determine whether genomic factors, such as MUC5B promoter polymorphism or telomere length, modify these associations. We performed analyses at enrollment and after one year of follow-up in the IPF-PRO Registry, a prospective observational registry that enrolled individuals with IPF at 46 US sites from June 2014 to October 2018. Five-year average pollution exposures (PM2.5, NO2, O3) prior to enrollment date were estimated at participants' residential addresses with validated national spatio-temporal models. Multivariable regression models estimated associations between pollution exposure and physiologic measurements (FVC, DLCO, supplemental oxygen use at rest) and quality of life measurements (St. George's Respiratory Questionnaire [SGRQ], EuroQoL, Cough and Sputum Assessment Questionnaire) at enrollment. Cox proportional hazard models estimated associations between pollutants and a composite outcome of death, lung transplant, or >10% absolute decline in FVC % predicted in the year after enrollment. Models were adjusted for individual-level and spatial confounders, including proxies for disease onset. Gene-environment interactions with MUC5B and telomere length were assessed. Of 835 participants, 94% were non-Hispanic Whites, 76% were male, mean (SD) age was 70 (7.7) years. In fully adjusted analyses, higher PM2.5 exposure was associated with worse quality of life per SGRQ activity score (3.48 [95% confidence interval (CI) 0.64, 6.32] per 2µg/m3 PM2.5) and EuroQoL scores (-0.04 [95%CI -0.06, -0.01] per 2µg/m3 PM2.5), and lower FVC % predicted and lower DLCO% predicted at enrollment. Each 3 parts per billion difference in O3 exposure was associated with a 1.57% [95% CI 0.15, 2.98] higher FVC % predicted at enrollment, although this effect was attenuated in multi-pollutant models. There was no association between NO2 and enrollment measures, between pollution exposure and one-year outcomes, or evidence for gene-environment interactions. In the IPF-PRO Registry, long-term exposure to PM2.5 was associated with worse quality of life and lung function at enrollment, but not with short-term disease progression or mortality. There was no evidence of effect modification by interaction of genomic factors with pollution. The reason for the unexpected relationship between O3 exposure and higher FVC is unclear.

Obstructive sleep apnea in patients with fibrotic interstitial lung disease (non-idiopathic pulmonary fibrosis): what should be offered?

Objective: The frequency of obstructive sleep apnea (OSA) in patients with idiopathic pulmonary fibrosis (IPF) is high. The clinical course of non-IPF interstitial lung disease (ILD) can be similar to that of IPF. We sought to assess the frequency and predictors of OSA in patients with non-IPF fibrotic ILD, as well as the impact of positive airway pressure (PAP) therapy on the quality of life of such patients. Methods: This was a prospective study in which non-IPF fibrotic ILD patients underwent a home sleep apnea test. The patients with and without OSA were compared, and a multivariate logistic regression model was used to identify independent predictors of OSA. At 3 months after initiation of PAP therapy, we evaluated the participating patients for respiratory events, nocturnal hypoxemia, and changes in quality of life. Results: Of a total of 50 patients, 50% were male, and 76% were diagnosed with OSA. The mean age was 67.8 ± 8.3 years. The patients with OSA had significantly lower TLC (p = 0.033) and awake SpO2 (p = 0.023) than did those without OSA. In the multivariate logistic regression model, SpO2 (OR = 0.46; p = 0.016) and TLC (OR = 0.95; p = 0.026) remained significantly associated with OSA risk. A total of 12 patients received PAP therapy. At 3 months after initiation of PAP therapy, 91.7% were well controlled, Epworth Sleepiness Scale scores decreased significantly (p = 0.006), and emotional well-being tended to improve (p = 0.068). PAP therapy corrected nocturnal hypoxemia in all patients. Conclusions: We found a high frequency of OSA in patients with non-IPF fibrotic ILD. A low TLC was an independent predictor of a higher risk of OSA. PAP therapy can correct nocturnal hypoxemia. There should be a low threshold for suspicion of OSA and initiation of PAP therapy in patients with non-IPF fibrotic ILD.

Modulating Fibrotic Mechanical Microenvironment for Idiopathic Pulmonary Fibrosis Therapy.

Idiopathic pulmonary fibrosis (IPF) is exacerbated by injurious mechanical forces that destabilize the pulmonary mechanical microenvironment homeostasis, leading to alveolar dysfunction and exacerbating disease severity. However, given the inherent mechanosensitivity of fibrotic lungs, where type II alveolar epithelial cells (AEC IIs) are subjected to persistent stretching and overactivated myofibroblasts experience malignant interactions during mechanotransduction, it becomes imperative to develop effective strategies to modulate the pulmonary mechanical microenvironment. Herein, cyclo (RGDfC) peptide-decorated zeolitic imidazolate framework-8 nanoparticles (named ZDFPR NPs) are constructed to target and repair the aberrant mechanical force levels in pathological lungs. Specifically, reduces mechanical tension in AEC IIs by pH-responsive ZDFPR NPs that release zinc ions and 7, 8-dihydroxyflavone to promote alveolar repair and differentiation. Meanwhile, malignant interactions between myofibroblast contractility and extracellular matrix stiffness during mechanotransduction are disrupted by the fasudil inhibition ROCK signaling pathway. The results show that ZDFPR NPs successfully restored pulmonary mechanical homeostasis and terminated the fibrosis process in bleomycin-induced fibrotic mice. This study not only presents a promising strategy for modulating pulmonary mechanical microenvironment but also pioneers a novel avenue for IPF treatment.

Spirotetrahydroisoquinoline-Based Histone Deacetylase Inhibitors as New Antifibrotic Agents: Biological Evaluation in Human Fibroblasts from Bronchoalveolar Lavages of Idiopathic Pulmonary Fibrosis Patients

Spirotetrahydroisoquinoline-Based Histone Deacetylase Inhibitors as New Antifibrotic Agents: Biological Evaluation in Human Fibroblasts from Bronchoalveolar Lavages of Idiopathic Pulmonary Fibrosis Patients

Serum soluble isoform of receptor for advanced glycation end product is a predictive biomarker for acute exacerbation of idiopathic pulmonary fibrosis: a German and Japanese cohort study.

The receptor for advanced glycation end product (RAGE) is a transmembrane receptor accelerating a pro-inflammatory signal. RAGE signalling is promoted by decreased soluble isoform of RAGE (sRAGE), which is a decoy receptor for RAGE ligands, and RAGE SNP rs2070600 minor allele. In Caucasian and Japanese cohorts, low circulatory sRAGE levels and presence of the minor allele are associated with poor survival of idiopathic pulmonary fibrosis (IPF) and increased disease susceptibility to interstitial lung disease, respectively. However, whether sRAGE and RAGE SNP rs2070600 are associated with acute exacerbation of IPF (AE-IPF) is unclear. This retrospective cohort study evaluated the association between the onset of AE-IPF and serum sRAGE levels in 69 German and 102 Japanese patients with IPF. The association of AE-IPF with RAGE SNP rs2070600 in 51 German and 84 Japanese patients, whose DNA samples were stored, was also investigated. In each cohort, the incidence of AE-IPF was significantly and reproducibly higher in the patients with sRAGE < 467.1pg/mL. In a pooled exploratory analysis, the incidence of AE-IPF was lowest in the patients with higher sRAGE levels and rs2070600 minor allele, although no significant difference in the incidence was observed between the patients with and without the rs2070600 minor allele. Low sRAGE levels were associated with increased incidence of AE-IPF in two independent cohorts of different ethnicities. The combination of rs2070600 and sRAGE levels may stratify patients with IPF for the risk of AE.

Overexpression of STX11 alleviates pulmonary fibrosis by inhibiting fibroblast activation via the PI3K/AKT/mTOR pathway

Fibroblast activation plays an important role in the occurrence and development of idiopathic pulmonary fibrosis (IPF), which is a progressive, incurable, and fibrotic lung disease. However, the underlying mechanism of fibroblast activation in IPF remains elusive. Here, we showed that the expression levels of STX11 and SNAP25 were downregulated in the lung tissues from patients with IPF and mice with bleomycin (BLM)-induced lung fibrosis as well as in the activated fibroblasts. Upregulation of STX11 or SNAP25 suppressed TGF-β1-induced activation of human lung fibroblasts (HLFs) via promoting autophagy. However, they failed to suppress fibroblast actviation when autophagy was blocked with the use of chloroquine (CQ). In addition, STX11 or SNAP25 could inhibit TGF-β1-induced fibroblast proliferation and migration. In vivo, overexpression of STX11 exerted its protective role in the mice with BLM-induced lung fibrosis. STX11 and SNAP25 mutually promoted expression of each other. Co-IP assay indicated that STX11 has an interaction with SNAP25. Mechanistically, STX11-SNAP25 interaction activated fibroblast autophagy and further inhibited fibroblast activation via blocking the PI3K/AKT/mTOR pathway. Overall, the results suggested that STX11-SNAP25 interaction significantly inhibited lung fibrosis by promoting fibroblast autophagy and suppressing fibroblast activation via blocking the PI3K/ATK/mTOR signaling pathway. Therefore, STX11 serves as a promising therapeutic target in IPF.

Computed tomography morphological assessments of central airways in interstitial lung abnormalities and idiopathic pulmonary fibrosis

BackgroundLittle is known about whether central airway morphological changes beyond traction bronchiectasis develop and affect clinical outcomes in patients with idiopathic pulmonary fibrosis (IPF). This study aimed to compare central airway structure comprehensively between patients with IPF, subjects with interstitial lung abnormality (ILA), and those without ILA (control) using computed tomography (CT). We further examined the prognostic impact of IPF-specific CT airway parameters in patients with IPF.MethodsThis retrospective study included male patients with IPF, and male health checkup subjects divided into those with ILA and control based on lung cancer screening CT. Using an artificial intelligence-based segmentation technique, the extent of fibrotic regions in the lung was quantified. After airway tree segmentation, CT parameters for central airway morphology, including the lumen area of the extrapulmonary airways (LAextra), wall and lumen area of the segmental/subsegmental intrapulmonary airways (WAintra and LAintra), tracheal distortion (tortuosity and curvature) and bifurcation angle of the main carina, were calculated.ResultsThere were 106 patients with IPF, 53 subjects with ILA, and 1295 controls. Multivariable models adjusted for age, height and smoking history revealed that LAintra and WAintra were larger in both ILA and IPF, and that tracheal tortuosity and curvature were higher in IPF, but not in ILA, than in the control, whereas the bifurcation angle did not differ between the 3 groups. According to multivariable Cox proportional hazards models including only patients with IPF, increased WAintra was significantly associated with greater mortality (standardized hazard ratio [95% confidence interval] = 1.58 [1.17, 2.14]), independent of the volume of fibrotic regions, normal-appearing regions, or the whole airway tree in the lung.ConclusionIncreased lumen area and wall thickening of the central airways may be involved in the pathogenesis of ILA and IPF, and wall thickening may affect the prognosis of patients with IPF.

Neurocognitive and Neuropsychiatric Implications of Fibrosing Interstitial Lung Diseases

Patients with interstitial lung diseases (ILDs) associate a large variety of comorbidities that have a significant impact on their clinical outcomes and survival. Among these comorbidities is neurological impairment. This review highlights what is known about the cognitive function, central nervous system (CNS), depression, and anxiety in patients with specific forms of fibrosing ILDs, such as idiopathic pulmonary fibrosis, sarcoidosis, hypersensitivity pneumonitis, connective tissue diseases, etc. The most common pathogenic mechanisms for neurocognitive dysfunction as well as the screening methods and tools for their identification are also described in this review.

Molecular characterization of PANoptosis-related genes associated with immune infiltration and prognosis in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic pulmonary disease with unknown pathogenesis and poor prognosis. PANoptosis, a newly identified form of inflammatory programmed cell death, has been implicated in various inflammatory lung diseases. This study aimed to identify differentially expressed PANoptosis-related genes (PRDEGs) associated with immune infiltration and prognosis in IPF, while also establishing a novel prognostic prediction model. A total of 63 PRDEGs were identified from GSE110147 dataset, with 31 exhibiting consistent expression trends in GSE213001. Enrichment analysis indicated that the majority of these PRDEGs were enriched in inflammatory and immune-related pathways. Three key PRDEGs—NLRP3, ATM, and VEGFA—were selected through univariate and multivariable Cox regression analyses. The prognostic prediction model developed from these key PRDEGs demonstrated robust predictive performance. Furthermore, the expression of most PRDEGs was positively correlated with pro-inflammatory immune cells, including macrophages, neutrophils, and CD4+ T cells. Validation of the expression levels of these key PRDEGs was conducted in fibrotic mouse lung tissue. This study suggests that PANoptosis plays a role in IPF, potentially linked to the infiltration of pro-inflammatory immune cells, and may influence disease progression through the regulation of inflammatory immune signaling pathway. A new prognostic prediction model for IPF based on PRDEGs was successfully developed.

Prevalence, Clinical Features, and Outcomes of Young Patients with Idiopathic Pulmonary Fibrosis

Plain Language SummaryThis study examined the clinical features and outcomes of younger patients with idiopathic pulmonary fibrosis (IPF). Results showed that young patients with IPF exhibit lower risks of mortality and lung transplantation but are more often treated with steroids and less frequently with pirfenidone, potentially increasing these risks. These findings highlight the need for a strategic shift toward treatment approaches tailored for younger patients to avoid harmful treatments.

Vascular involvement in idiopathic pulmonary fibrosis

Vascular involvement in idiopathic pulmonary fibrosis

Convergent and divergent immune aberrations in COVID-19, post-COVID-19-Interstitial Lung Disease and Idiopathic Pulmonary Fibrosis.

We aimed to study transcriptional and phenotypic changes in circulating immune cells associated with increased risk of mortality in COVID-19, resolution of pulmonary fibrosis in post-COVID-19-Interstitial Lung Disease (ILD) and persistence of Idiopathic Pulmonary Fibrosis. Whole blood and Peripheral Blood Mononuclear cells (PBMC) were obtained from 227 subjects with COVID-19, post-COVID-19 Interstitial Lung Disease (ILD), IPF and controls. We measured a 50-gene signature (nCounter, Nanostring) previously found to be predictive of IPF and COVID-19 mortality along with plasma levels of several biomarkers by Luminex. Additionally, we performed single-cell RNA sequencing in PBMC (10X Genomics) to determine the cellular source of the 50-gene signature. We identified the presence of three genomic risk profiles in COVID-19 based on the 50-gene signature associated with low, intermediate, or high-risk of mortality and with significant differences in pro-inflammatory and pro-fibrotic cytokines. COVID-19 patients in the high-risk group had increased expression of seven genes in CD14+HLA-DRlowCD163+Monocytic-Myeloid-Derived Suppressive cells (7Gene-M-MDSCs) and decreased expression of 43 genes in CD4 and CD8 T cell subsets. The loss of 7Gene-M-MDSC and increased expression of these 43 genes in T cells was seen in survivors with post-COVID-19-ILD. On the contrary, IPF patients had low expression of the 43 genes in CD4 and CD8 T cells. Collectively, we showed that a 50-gene, high-risk profile, predictive of IPF and COVID-19 mortality is characterized by a genomic imbalance in monocyte and T-cell subsets. This imbalance reverses in survivors with post-COVID-19-ILD highlighting genomic differences between post-COVID-19-ILD and IPF.