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PubMed2026

Cystathionine γ-Lyase-Dependent S-Sulfhydration of Smad3: A Novel Target to Alleviate Fibrosis in Systemic Sclerosis.

OBJECTIVE: The cystathionine γ-lyase (CSE)/hydrogen sulfide (H2S) axis has emerged as a key regulator in tissue fibrogenesis. This study aimed to explore the role of the CSE/H2S axis in systemic sclerosis (SSc) and to investigate its underlying mechanisms to identify promising therapeutic targets. METHODS: CSE/H2S levels were assessed in serum samples from 25 patients with SSc and 28 healthy controls. Human dermal fibroblasts from patients with SSc and healthy controls were used for functional studies, including propargylglycine (CSE inhibitor) treatment, Gyy4137, a slow-releasing hydrogen sulfide donor, CSE silencing, and CSE overexpression, combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based S-sulfhydration proteomics. Molecular dynamics simulations were performed to study the effects of S-sulfhydration on protein structure, and an Smad3 C121S (cysteine [Cys] 121 mutated to Ser) mutant was generated to verify the function targets of S-sulfhydration. In vivo, bleomycin-induced mouse models of skin and lung fibrosis were constructed to evaluate the effects of CSE overexpression. RESULTS: In human samples, CSE/H2S levels were reduced in SSc. CSE inhibition promoted extracellular matrix deposition. S-sulfhydration proteomics showed that S-sulfhydration levels were globally reduced in SSc compared to controls. CSE overexpression increased S-sulfhydration on Smad3, suppressed transforming growth factor β 1 (TGFβ1)/Smad3 signaling, mitigating skin fibrosis. Notably, Cys121 on Smad3, identified as a pivotal target for S-sulfhydration by proteomics, was shown to fine-tune its MH1 domain, with its mutation impairing the antifibrotic effects. In mice, CSE overexpression attenuated bleomycin-induced skin and lung fibrosis. CONCLUSION: Smad3 S-sulfhydration mediates the antifibrotic effect of CSE in SSc, highlighting it as a critical mechanism and promising therapeutic target.

Humans↗
PubMed2025

Hypoxia-inducible factor 2 regulates alveolar regeneration after repetitive injury in three-dimensional cellular and in vivo models.

Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease in which repetitive epithelial injury and incomplete alveolar repair result in accumulation of profibrotic intermediate/transitional "aberrant" epithelial cell states. The mechanisms leading to the emergence and persistence of aberrant epithelial populations in the distal lung remain incompletely understood. By interrogating single-cell RNA sequencing (scRNA-seq) data from patients with IPF and a mouse model of repeated lung epithelial injury, we identified persistent activation of hypoxia-inducible factor (HIF) signaling in these aberrant epithelial cells. Using mouse genetic lineage-tracing strategies together with scRNA-seq, we found that these disease-emergent aberrant epithelial cells predominantly arose from airway-derived (Scgb1a1-CreER-traced) progenitors and exhibited transcriptional programs of Hif2a activation. In mice treated with repetitive intratracheal bleomycin, deletion of Epas1 (Hif2a) but not Hif1a, from airway-derived progenitors, or administration of the small-molecule HIF2 inhibitor PT-2385, using both prevention and rescue approaches, attenuated experimental lung fibrosis, reduced the appearance of aberrant epithelial cells, and promoted alveolar repair. In mouse alveolar organoids, genetic or pharmacologic inhibition of Hif2 promoted alveolar differentiation of airway-derived epithelial progenitors. In addition, treatment of human distal lung organoids with PT-2385 increased colony-forming efficiency, enhanced protein and transcriptional markers of alveolar type 2 epithelial cell maturation, and prevented the emergence of aberrant epithelial cells. Together, these studies showed that HIF2 activation drives the emergence of aberrant epithelial populations after repetitive injury and that targeted HIF2 inhibition may represent an effective therapeutic strategy to promote functional alveolar repair in IPF and other interstitial lung diseases.

Animals↗
PubMed2026

BET inhibition blunts antibody production and macrophage-mediated fibrosis to restore lung function in murine cGVHD.

Chronic graft-versus-host disease (cGVHD) significantly contributes to late mortality after allogeneic stem cell transplantation, with bronchiolitis obliterans syndrome (BOS) being a particularly lethal and treatment-resistant complication despite available therapies. Bromodomain and extraterminal (BET) proteins are epigenetic readers driving inflammatory transcriptional programs across multiple cell types. We hypothesized that BET inhibition would suppress inflammatory T and B cells and decrease macrophage polarization to a profibrotic phenotype, alleviating disease. In an established BOS cGVHD model, BET inhibition reduced germinal center (GC) formation and responses through a reduction of the CXCL13:CXCR5 axis and inflammatory T follicular helper/GC B cells in the spleen, along with a reduction in plasma cell infiltration within the lung. Mice with cGVHD had elevated pathogenic immunoglobulin G1 (IgG1) and IgM levels, both in circulation and deposited on lung tissue, which were attenuated under BET inhibition. Single-cell RNA-sequencing analysis revealed distinct cell states in the BOS lung vs control. In cGVHD mice, gene set enrichment analysis revealed the upregulation of profibrotic Arginase1 and Tgfb1 expression in alveolar macrophages (AM) and interstitial macrophages (IM), which was significantly reduced with BET inhibition. Furthermore, BET inhibition targeted lung-infiltrating M2 macrophages through the selective depletion of CD206+FcγR+ IM and AM, ultimately resulting in reduced collagen deposition and improved lung function. Our findings reveal a previously unrecognized mechanistic axis of BET regulation during cGVHD fibrosis and highlight BET inhibition as a promising therapeutic strategy.

Animals↗
PubMed2026

Achromobacter species in cystic fibrosis and chronic lung disease: a review of virulence, antibiotic resistance, diagnostic challenges, and emerging therapies.

Achromobacter species (spp) is an emerging opportunistic organism more frequently isolated from immunocompromised patients' and hospital settings. This bacterium was once considered an environmental bacterium, but now it is recognized as a serious cause of respiratory infections, bloodstream infections, and urinary tract infections, particularly among patients with cystic fibrosis (CF), chronic illnesses, and medical devices. The purpose of this review is to highlight Achromobacte's clinical significance, pathogenic mechanism, and recent approaches for diagnosis and treatment. By utilizing specific keywords relevant to Achromobacter spp., a comprehensive literature search was performed in PubMed and Google Scholar. To summarize existing knowledge and highlight gaps in the literature, peer-reviewed studies on clinical relevance, pathogenicity, antimicrobial resistance, and therapeutic approaches were gathered, screened, and narratively assembled. Among the 19 identified species, Achromobacter xylosoxidans (A. xylosoxidans) is the most prevalent and clinically relevant, especially in CF settings. This review explores the organism's microbiological characteristics, virulence strategies-including robust biofilm formation, motility, and secretion systems-and its alarming intrinsic and acquired resistance to antibiotics. Misidentification due to phenotypic overlap with other non-fermenting Gram-negative bacilli complicates diagnosis, while limited MALDI-TOF MS and database representation hinders species-level identification. Genotyping methods, including multi-locus sequence analysis and housekeeping gene sequencing, offer superior resolution but remain underutilized in clinical diagnostics. With rising resistance mediated by β-lactamases, efflux pumps, and adaptive genomic traits, Achromobacter spp presents a growing challenge for treatment and infection control. This review highlights the urgent need for improved diagnostic strategies, species-level clinical and microbiological data, and tailored therapeutic approaches to manage Achromobacter spp. infections effectively.

Humans↗
PubMed2026

MASLD Exacerbates Chronic Low-dose PM2.5-induced Lung Injury, Inflammation, and Fibrosis.

BACKGROUND/AIM: Fine particulate matter (PM2.5) and metabolic dysfunction-associated steatotic liver disease (MASLD) are independent risk factors for respiratory disease. However, the combined impact of chronic, low-dose PM2.5 exposure and Western diet (WD)-induced metabolic dysfunction on pulmonary health remains poorly understood. We investigated whether this metabolic state exacerbates PM2.5-driven pathologies using an environmentally relevant PM2.5 dosage (~50 μg/m3). MATERIALS AND METHODS: C57BL/6J mice were fed a WD or normal diet (ND) for 28 weeks and concurrently received intratracheal instillations of PM2.5 (0.5 mg/kg diesel particulate matter) or vehicle three times per week. The MASLD phenotype was confirmed through metabolic and histological analyses. Pulmonary injury, fibrosis, and inflammation were assessed via histology (hematoxylin and eosin, and Masson's trichrome staining) and cytokine quantification in both bronchoalveolar lavage fluid using Luminex multiplex assay and lung tissue using enzyme-linked immunosorbent assay and quantitative polymerase chain reaction. RESULTS: The WD successfully induced MASLD characterized by weight gain, hepatic steatosis, and dyslipidemia. While PM2.5 exposure did not significantly worsen the primary features of MASLD, its combination with a WD markedly exacerbated pulmonary injury and fibrosis compared to PM2.5 exposure alone. This exacerbation was driven by a surge in pro-inflammatory chemokines, including C-X-C motif chemokine ligands 1 and 2 (CXCL1 and CXCL2), and C-C motif chemokine ligand 5 (CCL5), confirmed by Luminex analysis of lavage fluid and mRNA/protein quantification in lung tissue. CONCLUSION: Diet-induced metabolic dysfunction primes the lung for a hyper-inflammatory response to chronic PM2.5 exposure. These findings identify individuals with MASLD as a population with heightened susceptibility to air pollution-related respiratory diseases and underscore the critical interplay between metabolic health and environmental toxicology.

Animals↗
PubMed2025

Associations of High Attenuation Area-Related Proteomic Biomarkers with Fibrotic or Subpleural Interstitial Lung Abnormalities.

Rationale: High-attenuation area (HAA) is a computed tomography (CT) tool that correlates with lung inflammation and fibrosis. Systemic molecular correlates of HAA (e.g., plasma proteins) may inform biological processes involved in interstitial lung disease. Objectives: To identify plasma proteins that associate with HAA and correlate with a higher probability of developing new-onset fibrotic or subpleural interstitial lung abnormalities (ILAs). Methods: Plasma protein levels were measured using a semiquantitative aptamer-based platform in MESA (the Multi-Ethnic Study of Atherosclerosis; N = 5,486) and SPIROMICS (Subpopulations and Intermediate Outcome Measures in COPD Study; N = 1,781). Linear regression models identified HAA-associated proteins after adjustment for demographic and socioeconomic factors, CT scanner parameters, study center, and batch. Associations of HAA-related proteins with new-onset fibrotic or subpleural ILAs were examined in MESA participants with ILA assessments on full-lung CT 10 years later. Immunohistochemical staining of select proteins was performed in lung tissue from pulmonary fibrosis cases. Measurements and Main Results: There were 75 proteins detected that were significantly associated with HAA in MESA and SPIROMICS. Gene Ontology analysis of these proteins identified processes involved in immune cell chemotaxis and cellular growth and apoptosis. Seven proteins were associated with a higher probability of new-onset fibrotic or subpleural ILAs in MESA, and two of these, junctional adhesion molecule-like protein and GTP cyclohydrolase 1 feedback regulatory protein, stained in areas of fibrosis in lung tissue from patients with interstitial lung disease. Conclusions: Plasma proteins associated with more HAA are involved in immune and cellular processes and associate with new-onset fibrotic-subpleural ILA.

Humans↗
PubMed2026

Donor selection in living-donor lung transplantation for familial pulmonary fibrosis: A narrative review and single-center practical approach.

In Japan, living-donor lobar lung transplantation (LDLLT) remains an important therapeutic option because of the persistent shortage of brain-dead donors. Interstitial lung diseases (ILDs) are a major indication for transplantation; however, the use of biologically related donors raises concerns regarding shared genetic susceptibility. Approximately 20% of ILD patients have a family history of ILD, referred to as familial pulmonary fibrosis (FPF). FPF is defined as fibrotic ILD occurring in at least two first- or second-degree relatives and is associated with poor prognosis regardless of the presence of identifiable genetic variants. Furthermore, interstitial lung abnormalities have been reported in 14-22% of first-degree relatives of patients with FPF, suggesting a substantial latent risk of disease development both in donors and recipients. These findings have important implications for donor selection in LDLLT. At Kyoto University Hospital, first-degree relatives from affected lineages are generally excluded as donor candidates, whereas relatives from unaffected family branches may be considered after careful individual assessment. Even in cases without a family history, biologically related donor candidates should be adequately informed of the potential future risk of ILD. Future directions include the incorporation of genetic testing and telomere length assessment and the establishment of prospective cohorts to enable risk stratification and long-term outcome evaluation. In conclusion, the selection of donors for LDLLT in patients with FPF requires a cautious and individualized approach that integrates family history, clinical evaluation, and genetic information to balance donor safety with access to transplantation.

Humans↗
PubMed2026

Obese adipocytes induce fibroblast-to-myofibroblast transition through TGF-β1 signaling: implications in asthma pathogenesis.

Obesity, a key risk factor for severe asthma, is associated with worsening symptoms and poor responses to conventional therapies. Recent studies have highlighted the presence of adipocytes within airway walls, which correlates positively with body mass index (BMI). However, the role of adipocytes in asthma pathogenesis remains largely unknown. This study aims to explore their potential contribution to airway fibrosis, a progressive form of the disease, through fibroblast-to-myofibroblast transition (FMT). In vitro coculture models were developed to investigate the interactions between adipocytes (derived from patients with and without obesity) and fibroblasts (from patients with and without asthma) on FMT. Proteomic and multiplex analyses were used to identify potential mediators of adipocyte-induced FMT. Our data revealed a significant increase in fibrogenic markers, such as alpha-smooth muscle actin and vimentin, in fibroblasts cocultured with obese (Ob) adipocytes. Notably, this transition was more pronounced in asthmatic fibroblasts compared with healthy fibroblasts. Proteomic profiling of cocultured Ob-adipocytes and asthmatic fibroblasts identified several significantly upregulated proteins linked to the regulation of the transforming growth factor-beta (TGF-β) signaling pathway, including inhibin A, latent TGF-β binding protein 1, thrombospondin 1, and follistatin. The role of TGF-β was further substantiated by multiplex assays, which demonstrated a significant increase in TGF-β and leptin production by Ob-adipocytes following coculture. These findings suggest that Ob-adipocytes may promote FMT in fibroblasts, especially asthmatic fibroblasts, by activating the TGF-β signaling pathway. This highlights a potential mechanism by which obesity exacerbates asthma severity and fibrosis, providing new avenues for therapeutic intervention.NEW & NOTEWORTHY Adipocytes have been found in the airway wall of patients with obesity. This study is the first to show that adipocytes derived from patients with obesity can induce features of airway remodeling that is seen in patients with asthma such as fibroblast-to-myofibroblast transition via the TGF-beta signaling pathway in an indirect mode of cellular communication. This highlights a potential mechanism by which obesity exacerbates asthma severity and fibrosis, providing new avenues for therapeutic intervention.

Humans↗
PubMed2022

Cystic Fibrosis Airway Mucus Hyperconcentration Produces a Vicious Cycle of Mucin, Pathogen, and Inflammatory Interactions that Promotes Disease Persistence.

The dynamics describing the vicious cycle characteristic of cystic fibrosis (CF) lung disease, initiated by stagnant mucus and perpetuated by infection and inflammation, remain unclear. Here we determine the effect of the CF airway milieu, with persistent mucoobstruction, resident pathogens, and inflammation, on the mucin quantity and quality that govern lung disease pathogenesis and progression. The concentrations of MUC5AC and MUC5B were measured and characterized in sputum samples from subjects with CF (N = 44) and healthy subjects (N = 29) with respect to their macromolecular properties, degree of proteolysis, and glycomics diversity. These parameters were related to quantitative microbiome and clinical data. MUC5AC and MUC5B concentrations were elevated, 30- and 8-fold, respectively, in CF as compared with control sputum. Mucin parameters did not correlate with hypertonic saline, inhaled corticosteroids, or antibiotics use. No differences in mucin parameters were detected at baseline versus during exacerbations. Mucin concentrations significantly correlated with the age and sputum human neutrophil elastase activity. Although significantly more proteolytic cleavages were detected in CF mucins, their macromolecular properties (e.g., size and molecular weight) were not significantly different than control mucins, likely reflecting the role of S-S bonds in maintaining multimeric structures. No evidence of giant mucin macromolecule reflecting oxidative stress-induced cross-linking was found. Mucin glycomic analysis revealed significantly more sialylated glycans in CF, and the total abundance of nonsulfated O-glycans correlated with the relative abundance of pathogens. Collectively, the interaction of mucins, pathogens, epithelium, and inflammatory cells promotes proteomic and glycomic changes that reflect a persistent mucoobstructive, infectious, and inflammatory state.

Cystic Fibrosis↗
PubMed2026

Humanizing acidic mammalian chitinase variants establish lung immune conditioning and control environmentally driven inflammation and fibrosis.

Chitin, a widespread environmental particle constituent, triggers lung inflammation but is degraded by chitinases. In humans, single-nucleotide polymorphisms (SNPs) in CHIA (acidic mammalian chitinase; AMCase) are associated with lung disease, suggesting that chitinase variants influence responses to airborne particles. Here, we edit the mouse Chia1 locus to generate humanized (hChia) mice harboring common human SNPs. Compared with controls expressing disease-protective SNPs, hChia mice lack robust chitinase activity and fail to degrade natural chitin substrates. Lung-resident lymphocytes and macrophages are spontaneously primed and sensitive to inflammatory triggering by environmental chitin. Immune cell infiltration correlates with airway chitin following challenge, and hChia mice exhibit exacerbated inflammatory and fibrotic lung disease. In humans with acute respiratory failure, alveolar hemorrhage coincides with environmentally derived chitin particles that are susceptible to chitinase degradation, attenuating inflammatory cell responses. Thus, environmental chitin and chitinase activity are crucial determinants of lung immune conditioning with potential therapeutic applications.

AMCase↗
PubMed2025

Polygenic risk scores for rheumatoid arthritis and idiopathic pulmonary fibrosis and associations with RA, interstitial lung abnormalities, and quantitative interstitial abnormalities among smokers.

OBJECTIVE: Genome-wide association studies (GWAS) facilitate construction of polygenic risk scores (PRSs) for rheumatoid arthritis (RA) and idiopathic pulmonary fibrosis (IPF). We investigated associations of RA and IPF PRSs with RA and high-resolution chest computed tomography (HRCT) parenchymal lung abnormalities. METHODS: Participants in COPDGene, a prospective multicenter cohort of current/former smokers, had chest HRCT at study enrollment. Using genome-wide genotyping, RA and IPF PRSs were constructed using GWAS summary statistics. HRCT imaging underwent visual inspection for interstitial lung abnormalities (ILA) and quantitative CT (QCT) analysis using a machine-learning algorithm that quantified percentage of normal lung, interstitial abnormalities, and emphysema. RA was identified through self-report and DMARD use. We investigated associations of RA and IPF PRSs with RA, ILA, and QCT features using multivariable logistic and linear regression. RESULTS: We analyzed 9,230 COPDGene participants (mean age 59.6 years, 46.4 % female, 67.2 % non-Hispanic White, 32.8 % Black/African American). In non-Hispanic White participants, RA PRS was associated with RA diagnosis (OR 1.32 per unit, 95 %CI 1.18-1.49) but not ILA or QCT features. Among non-Hispanic White participants, IPF PRS was associated with ILA (OR 1.88 per unit, 95 %CI 1.52-2.32) and quantitative interstitial abnormalities (adjusted β=+0.50 % per unit, p = 7.3 × 10-8) but not RA. There were no statistically significant associations among Black/African American participants. CONCLUSIONS: RA and IPF PRSs were associated with their intended phenotypes among non-Hispanic White participants but performed poorly among Black/African American participants. PRS may have future application to risk stratify for RA diagnosis among patients with ILD or for ILD among patients with RA.

Humans↗
PubMed2026

Multiomic analysis identifies T cell subsets and mechanisms of epithelial interaction in idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a fatal interstitial lung disease characterized by progressive scarring and respiratory failure. While T cells are elevated in IPF lungs, their contributions to fibrosis beyond inflammation remain poorly understood. Here, we performed multiplex imaging and single-cell RNA and protein profiling on about 90,000 CD3+ T cells from control and fibrotic lungs, revealing 11 distinct subsets of CD4+ and CD8+ T cells, including a rare CD56+ regulatory T cell. In addition to increased T cell numbers in severely fibrotic lungs compared with non-diseased controls, we observed CD4+ and CD8+ T cells localized near epithelial cells and in niches of abnormal epithelium. CXCR4/MIF signaling emerged as a central axis mediating T cell-epithelial interactions, while epidermal growth factor receptor (EGFR) and TGF-β pathways dominated in multiple T cell subsets. Our findings support the concept that T cells in IPF adopt nonclassical activation patterns that are driven by epithelial interactions within the fibrotic microenvironment. These studies provide a foundation for exploring alternative therapeutic strategies in IPF lungs by modulating T cell behavior and communication networks.

Idiopathic Pulmonary Fibrosis↗
PubMed2024

Longitudinal effects of elexacaftor/tezacaftor/ivacaftor on the oropharyngeal metagenome in adolescents with cystic fibrosis.

BACKGROUND: Triple modulator therapy elexacaftor/tezacaftor/ivacaftor (ETI) improves lung function and impacts upon the respiratory microbiome in people with Cystic fibrosis (pwCF) with advanced lung disease. However, adolescents with cystic fibrosis (CF) are less colonized with bacterial pathogens than adult pwCF but their microbiota already differs from healthy individuals. The aim of this study was to longitudinally analyze the impact of ETI on the respiratory metagenome in adolescents with predominantly mild CF lung disease. METHODS: In this prospective observational study, we included pwCF aged 12-20 years with at least one F508del mutation, who collected oropharyngeal swabs before and after initiation of ETI therapy twice per week to biweekly over three months. We performed whole metagenome shotgun sequencing, followed by host DNA filtering and taxonomic profiling. We used linear and additive mixed effects models adjusted for known confounders and corrected for multiple testing to study longitudinal development of the microbiome. We analyzed bacterial diversity, abundance, and strain-level phylogeny. RESULTS: We analyzed the metagenomic data of 297 swabs of 20 pwCF. Microbiome composition changed after initiation of ETI therapy. We observed a slight diversification of the microbiome over time (Inv Simpson, Coef 0.085, 95 %CI 0.003, 0.17, p = 0.04). Strain-level analysis and clustering showed that strain retention of the most frequent bacterial species is predominant even during ETI therapy. CONCLUSIONS: During three months of ETI therapy, commensal bacteria increased, which may help to prevent overgrowth of bacterial pathogens.

Humans↗
PubMed2025

Cellular imbalance in proximal and distal lung of CFTR-/- sheep in utero and at birth.

BACKGROUND: The Lung is the major focus of therapeutic approaches for the inherited disorder cystic fibrosis (CF) as without treatment lung disease is life-limiting. However, the initiating events that predispose the CF lung to cycles of infection, inflammation and resultant tissue damage are still unclear. Inflammation may occur in the CF lung prior to birth in human and several large animal models suggesting an in utero origin for the disease and encouraging further studies prior to birth. METHODS: Here we used the sheep model of CF (CFTR-/-) and age-matched wild-type (WT) sheep of the same breed to investigate the single cell transcriptomes of proximal and distal lung tissue at 80 days and 120 days of gestation and at term (147 days). Single cell RNA-seq was performed on tissues from 4 to 7 animals of each genotype (WT and CFTR-/-) at each time point. RESULTS: At term, FOXJ1-expressing ciliated cells are overrepresented in both lung regions from CFTR-/- lambs, while secretory epithelial and basal cells are underrepresented in proximal lung, as are T cells and monocytes in distal lung. The imbalance in ciliated and basal cells was confirmed by immunohistochemistry. At 120 days of gestation, lymphoid cells are slightly more abundant in proximal and distal lung from CFTR-/- animals compared to WT, consistent with the transient CF-associated inflammatory response in utero. At 80 days of gestation, T and B cells are underrepresented in both lung regions. CONCLUSIONS: The differences in epithelial cell abundance observed in the CFTR-/- lambs at term may reflect sequelae from the loss of CFTR on lung development and differentiation in utero. These findings provide novel insights into the cellular mechanisms of pathology and may be relevant to the design of new therapeutic approaches for CF lung disease.

Animals↗
PubMed2026

Amiloride mitigates respiratory distress caused by WFDC2 deficiency via inhibiting the epithelial sodium channel.

Chronic airway diseases such as cystic fibrosis (CF) and primary ciliary dyskinesia (PCD) pose substantial clinical challenges. Here, we explore the p.C97W variant in WAP four-disulfide core domain protein 2 (WFDC2), proposed as a new genetic origin of respiratory distress, especially among Koreans. Whole-exome and whole-genome sequencing (WES/WGS) are performed on 64 patients from 62 families presenting with severe bronchiectasis and chronic rhinosinusitis. Pathogenic variants are found in 19.4% of families, including a novel homozygous WFDC2 missense variant (c.291 C > G, p.Cys97Trp) in five unrelated families. WFDC2 is expressed in lung epithelial cells, and the p.C97W variant impairs WFDC2 protein folding, secretion, and function. Wfdc2 p.C147W knock-in mice exhibit respiratory failure due to the hyperactive epithelial sodium channel (ENaC) linked to increased PRSS8 activity and recapitulate human disease. Treatment with amiloride, an ENaC inhibitor, improves survival and respiratory function in these mice. In conclusion, the p.C97W variant in WFDC2 is a critical genetic factor in severe chronic airway disease that shares clinical features with CF and PCD. Given its implications for diagnosis and treatment, genetic testing for WFDC2 mutations in individuals with CF- or PCD-like symptoms is recommended.

Humans↗
PubMed2026

HDAC6 inhibition reduces Pseudomonas aeruginosa adherence and internalization in cystic fibrosis epithelial cells via microtubule stabilization.

Pseudomonas aeruginosa is a common opportunistic pathogen that causes chronic lung infections in individuals with cystic fibrosis. Despite advances in therapies that restore cystic fibrosis transmembrane conductance regulator function, persistent colonization of the airway remains a major clinical challenge. Reduced clearance of P. aeruginosa from the cystic fibrosis airway has been associated with the increased activity of histone deacetylase 6 (HDAC6), a cytoplasmic deacetylase that decreases microtubule acetylation and stability. In this study, we investigated the role of HDAC6 in modulating interactions between P. aeruginosa and cystic fibrosis airway epithelial cells. Pharmacologic inhibition of HDAC6 significantly reduced bacterial adherence in both mouse and human cystic fibrosis epithelial cells. Genetic deletion of HDAC6 produced similar effects, while knockout of a microtubule-stabilizing protein increased bacterial adherence, mimicking the cystic fibrosis phenotype. HDAC6 inhibition also reduced bacterial internalization, although to a lesser extent compared to adherence. These results suggest that microtubule destabilization contributes to the enhanced colonization of cystic fibrosis airways by P. aeruginosa. Targeting host microtubule regulatory pathways, particularly by inhibiting HDAC6, may represent a promising host-directed strategy to limit early bacterial attachment and reduce the risk of chronic infection in cystic fibrosis.

Pseudomonas aeruginosa↗
PubMed2025

FAM13A polymorphism is associated with a usual interstitial pneumonia pattern in patients with systemic sclerosis-associated interstitial lung disease.

OBJECTIVES: The MUC5B promoter single nucleotide polymorphism (SNP) rs35705950 has been associated with idiopathic pulmonary fibrosis (IPF) and RA-related interstitial lung disease (ILD), but not with SSc-ILD. We hypothesized that the MUC5B promoter polymorphism or other IPF susceptibility loci are associated with an increased risk for the uncommon SSc-usual interstitial pneumonia (UIP) endophenotype, rather than SSc-ILD in general. METHODS: We performed a cross-sectional study of SSc-ILD patients from four US Scleroderma Programs to investigate the frequency of MUC5B rs35705950 and 12 additional IPF susceptibility loci. SSc-ILD patients were stratified by high resolution chest CT (HRCT) imaging findings into UIP and non-UIP groups. Analysis of HRCTs performed by a thoracic radiologist blinded to participants' characteristics classified each scan as definite UIP, probable UIP, indeterminate or alternative diagnosis, according to American Thoracic Society criteria. RESULTS: Four-hundred and eighty-nine SSc-ILD patients were included; 80% were female and 75% were White. Twenty-three (4.7%) patients had a definite UIP pattern. The MUC5B SNP rs35705950 was not associated with a definite UIP pattern in SSc-ILD. In contrast, patients carrying two copies of the IPF risk gene FAM13A minor allele rs2609255 had significantly higher odds of a definite UIP pattern compared with the other patterns (odds ratio 3.40, 95% CI 1.19-9.70), and compared with an alternative diagnosis (odds ratio 3.65, 95% CI 1.25-10.65). CONCLUSION: We demonstrated a novel association between FAM13A and SSc-UIP. Contrary to IPF and RA-ILD, the MUC5B promoter polymorphism was not associated with a definite UIP pattern in SSc-ILD.

Humans↗
PubMed2026

A regulatory network underlying idiopathic pulmonary fibrosis.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease in which genetic susceptibility interacts with epithelial, immune, and mesenchymal remodeling. Although the chromosome 11p15.5 locus contains established IPF susceptibility signals near MUC5B and TOLLIP, the broader regulatory architecture of this region remains incompletely resolved. METHODS: We integrated IPF genome-wide association study summary statistics with methylation, expression, and protein quantitative trait loci using summary-data-based Mendelian randomization (SMR). SMR-prioritized candidates were evaluated in independent transcriptomic and methylation cohorts and further contextualized using microRNA, transcription-factor, protein-interaction, machine-learning, single-cell, and spatial transcriptomic analyses. Fibrosis-associated expression patterns were assessed in a bleomycin-induced pulmonary fibrosis rat model. RESULTS: The analyses recovered the established MUC5B and TOLLIP signals and prioritized BRSK2 as a comparatively underexplored candidate supported by eQTL-based SMR and independent molecular evidence. The BRSK2 pQTL association did not pass the HEIDI test and was therefore not interpreted as convergent protein-level genetic evidence. Network analyses linked BRSK2 to cell-cycle, metabolic-stress, and senescence-related programs, while cross-cohort machine learning prioritized FOXA2, CDC25B, and NFE2 as informative network features. Single-cell and spatial analyses localized BRSK2 preferentially to fibroblast and myofibroblast compartments and to regions with greater histological fibrosis severity. In fibrotic rat lungs, BRSK2 expression increased, whereas FOXA2 and CDC25B decreased at the transcript and protein levels. CONCLUSIONS: These findings refine the molecular landscape of the chromosome 11p15.5 IPF susceptibility locus and prioritize BRSK2 as a candidate component of an IPF-associated profibrotic fibroblast state. Its causal contribution, direct regulatory relationships, and therapeutic tractability require targeted mechanistic validation.

Idiopathic Pulmonary Fibrosis↗