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Pulmonary involvement usually is a late manifestation of progressive systemic sclerosis. In the case reported here, dyspnea and pulmonary interstitial fibrosis developed more than a year prior to onset of skin and vascular changes. Open-lung biopsy performed early in the course of the disease failed to yield a definitive diagnosis.
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Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal interstitial lung disease characterized by aberrant profibrotic signaling and excessive extracellular matrix deposition, accompanied by fibroblast-to-myofibroblast transition. Despite extensive investigation, the molecular mechanisms underlying IPF pathogenesis remain incompletely understood. Here, we investigated the role of triosephosphate isomerase 1 (TPI1) in IPF progression and its regulation by transforming growth factor-β (TGF-β) signaling. Loss-of-function analyses identified TPI1 as a downstream effector of TGF-β1, as its knockdown markedly suppressed fibrotic marker expression, fibroblast proliferation, and migration. Mechanistically, TWIST2 was shown to function as a direct transcriptional regulator of TPI1, binding to its promoter and promoting transcriptional activation. Rescue experiments further confirmed that the TWIST2-TPI1 axis is central to the progression of pulmonary fibrosis. Notably, knockdown of either TPI1 or TWIST2 effectively attenuated TGF-β1-induced fibrotic phenotypes. Collectively, these findings define the TGF-β1/TWIST2/TPI1 signaling axis as an important regulator of pathogenic fibroblast behavior and pro-fibrotic responses through transcriptional control of TPI1, highlighting its potential as a therapeutic target for IPF.
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.
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.
BACKGROUND: Pulmonary fibrosis (PF) is a progressive respiratory disease characterized by epithelial injury, aberrant repair and excessive extracellular matrix deposition. Although the gut-lung axis is increasingly implicated in respiratory disorders, stage-resolved characterization of gut microbiota taxonomic and functional potential during PF development is limited. METHODS: We established a bleomycin-induced murine PF model and performed cross-sectional shotgun metagenomic sequencing of fecal samples from separate cohorts at three defined stages: baseline (control), day 7 (early fibrosis; M7), and day 14 (established fibrosis; M14). Microbial taxonomy, alpha/beta diversity, and predicted functional capacity were inferred using Kyoto Encyclopedia of Genes and Genomes (KEGG) and Carbohydrate-Active enZymes (CAZy) annotations; associations were assessed using Procrustes and Spearman correlation analyses. RESULTS: Histopathology and immunohistochemistry confirmed progressive fibrogenesis with increased TGF-β1 and α-SMA expression. Compared with baseline, bleomycin-treated groups exhibited stage-specific shifts in gut microbial composition, including depletion of mucin-associated taxa (e.g., Prevotella, Akkermansia muciniphila) and expansion of Muribaculaceae- and Clostridiaceae-affiliated taxa. Alpha and beta diversity metrics differed across groups. KEGG/CAZy-based annotations revealed predicted, stage-dependent changes in microbial metabolic potential, including early reductions in pathways related to amino acid and glycan metabolism (M7) and later increases in predicted starch/sucrose catabolism, phosphotransferase system (PTS) representation, and secondary bile acid biosynthesis (M14). Correlation analyses linked compositional shifts to these predicted functional changes. CONCLUSION: In a stage-resolved, cross-sectional study, bleomycin-associated pulmonary fibrosis was accompanied by compositional and predicted functional alterations in the gut microbiota. These data identify candidate taxa and predicted pathways for follow-up mechanistic testing, but functional (metabolomic) and causality experiments are required to confirm whether and how microbial changes contribute to PF pathogenesis.
Idiopathic pulmonary fibrosis (IPF) is a progressive disease of lung parenchyma characterized by a chronic inflammatory cellular infiltration and varying degrees of interstitial fibrosis. Current data indicate that the severity of fibrosis and the degree of cellularity determine, in part, the prognosis of IPF and the response to therapy. Whereas lung biopsy gives the best assessement of fibrosis and cellularity, physiologic studies are used to stage and monitor the disease process. To determine which physiologic studies correlate best with severity of fibrosis and degree of cellularity, these parameters were graded in lung biopsies of 23 patients with IPF and compared with a variety of physiologic studies. Although vital capacity, total lung capacity, and diffusing capacity are commonly used as objective monitors of the disease process, none of these parameters correlated with either the severity of fibrosis or the degree of cellularity in biopsy specimens. In contrast, almost all parameters of lung distensibility correlated with the morphologic assessment of degree of fibrosis; compliance had the best correlation. Parameters of distensibility, however, correlated poorly with the degree of cellularity. In comparison, gas exchange during exercise correlated with both morphologic parameters; the exercise-induced changes in arterial oxygen pressure per liter of oxygen consumed had a high correlation with the degree of fibrosis (r = 0.89; P less than 0.001) and correlated to a lesser extent with the degree of cellularity (r = 0.56; P = 0.009). In contrast, neither the resting arterial oxygen tension nor the arterial oxygen tension at maximal exercise correlated with the morphologic assessment of degree of fibrosis or the degree of cellularity. These morphologic-physiologic comparisons suggest that (a) lung volumes and diffusing capacity are poor monitors of both the degree of fibrosis and the degree of cellularity; (b) the fibrotic process contributes, at least in part, to parameters of lung distensibility, and both fibrosis and cellularity contribute to gas exchange alterations during exercise; and (c) parameters of lung distensibility and exercise-induced gas exchange alterations may be useful in staging the severity of disease in IPF.
Pulmonary fibrosis was induced in eight baboons with bleomycin; five untreated animals were controls. After 45-65 U/kg of bleomycin, lung volumes and diffusing capacity were reduced, and static lung pressure-volume curves were shifted to the right. Right middle lobes were resected at this time in five bleomycin-treated and two control animals. Compared to controls, right middle lobes from bleomycintreated animals had increased weight and contained increased amounts of total protein, collagen, elastin, and DNA; synthesis of collagen and noncollagen protein were also elevated. Occasional alveolar septae were edematous and infiltrated by mononuclear inflammatory cells; a slight increase in collagen was demonstrable histologically. Four of six treated animals died with extensive diffuse interstitial fibrosis after 95 U/kg of bleomycin. Biochemical analyses revealed significantly elevated lobar contents of dry weight, protein, elastin, and collagen. Two animals survived 95 U/kg of bleomycin and were terminated 6 mo after treatment. In these animals, physiologic studies were indicative of restrictive lung disease, but lung histology was nearly normal. Lung weight, total protein, and DNA had returned to control values, but collagen and elastin were increased in amount and concentration. Bleomycin induces an intense inflammatory response in the lung. During this inflammation, connective tissue proliferation occurs in concert with proliferation of other tissue components. Cessation of bleomycin treatment is followed by resolution of inflammation manifested by decreases in tissue mass, cellular content, and nonconnective tissue protein. Collagen and elastin deposited during inflammation are less successfully removed during resolution, leading to a stage characterized by increased concentrations of these proteins. A similar sequence of tissue alterations may occur in idiopathic diffuse interstitial fibrosis of man in response to various lung injuries.
BACKGROUND: Post-Covid Pulmonary Fibrosis (PCPF) has emerged as a significant global issue associated with a poor quality of life and significant morbidity. Currently, our understanding of the molecular pathways of PCPF is limited. Hence, in this study, we performed whole transcriptome sequencing of the RNA isolated from the bronchoalveolar lavage (BAL) samples of PCPF and compared it with idiopathic pulmonary fibrosis (IPF) and non-ILD (Interstitial Lung Disease) control to understand the gene expression profile and associated pathways. METHODS: BAL samples from PCPF (n = 3), IPF (n = 3), and non-ILD Control (n = 3) (individuals with apparent healthy lung without interstitial lung disease) groups were obtained and RNA were isolated for whole transcriptomic sequencing. Differentially Expressed Genes (DEGs) were determined followed by functional enrichment analysis and qPCR validation. RESULTS: A panel of differentially expressed genes were identified in bronchoalveolar lavage fluid cells (BALF) of PCPF as compare to control and IPF. Our analysis revealed dysregulated pathways associated with cell cycle regulation, immune responses, and neuroinflammatory processes. Real-time validation further supported these findings. The PPI network and module analysis shed light on potential biomarkers and underscore the complex interplay of molecular mechanisms in PCPF. The comparison of PCPF and IPF identified a significant downregulation of pathways that were more prominent in IPF. CONCLUSION: This investigation provides crucial insights into the molecular mechanism of PCPF and also outlines avenues for prospective research and the development of therapeutic approaches.
Idiopathic pulmonary fibrosis is a fatal disorder characterized by interstitial fibrosis and parenchymal inflammation. Current concepts of this disease suggest that the inflammation precedes and probably induces the fibrotic state. To evaluate the extent and relative activity of the inflammatory process, we scanned patients with idiopathic pulmonary fibrosis using gallium-67, a radionuclide known to concentrate in regions of inflammation. To quantify the amount of isotope in the lung parenchyma, the 67Ga-index was developed, a parameter derived from estimates of the size of regional pulmonary uptake, the uptake intensity, and its texture. Evaluation of 67Ga scans in 30 patients with idiopathic pulmonary fibrosis and 19 control subjects demonstrated that the 67Ga-index in the group with idiopathic pulmonary fibrosis was significantly higher (P less than 0.001) than that in the control group. When compared with lung biopsy morphologic studies in 22 patients with idiopathic pulmonary fibrosis, the 67Ga-index correlated with the degree of interstitial cellularity (P less than 0.05) and the degree of alveolar cellularity (P less than 0.005). When compared with cellular analysis of bronchoalveolar lavage fluid in 17 patients with idiopathic pulmonary fibrosis, the 67Ga-index correlated with the differential percentage of neutrophils (P less than 0.05), but not lymphocytes, eosinophils, or macrophages. These studies indicate that 67Ga accumulates in the lungs of patients with idiopathic pulmonary fibrosis and is probably associated with the active inflammatory state. The associations of the 67Ga-index with morphologic features and bronchoalveolar lavage analysis suggest that quantitative evaluation of these scans may be useful in staging the activity of idiopathic pulmonary fibrosis and following responses to therapy.
INTRODUCTION: Most research on idiopathic pulmonary fibrosis (IPF) has focused on the interplay among fibroblasts, the immune system and epithelial cells. There is growing evidence that microvascular dysfunction also plays a role in disease progression, but large human translational studies are lacking. In this research, we aim to identify a proteomic signature of microvascular instability and assess the impact of current therapeutics on the microvasculature. METHODS: Olink proteomic data from patients with IPF were obtained from the Pulmonary Fibrosis Foundation Patient Registry (PFF-PR) (n=914) and an independent validation cohort (n=366). Among the PFF-PR, 640 patients also have whole-blood RNA sequencing data available. A subset of 79 microvascular-associated proteins was curated, and their associations with disease severity and transplant-free survival were examined. An adaptive least absolute shrinkage and selection operator was used to generate a novel microvascular risk score. RESULTS: Higher plasma levels of five microvascular-associated proteins (SDC1, MMP10, THBS2, HGF and SERPINA5) were associated with lung function and survival in both cohorts. Whole-blood RNA sequencing of patients with microvascular risk revealed enrichment of immune-mediated processes. Patients with higher microvascular risk who were subsequently put on nintedanib in the following year had significantly better 3-year transplant-free survival compared with patients who did not receive antifibrotic intervention (HR 0.56, 95% CI 0.35 to 0.89, p=0.0142). DISCUSSION: Integrative multi-omics analyses suggest that perturbations to microvascular remodelling contribute to disease severity and progression in IPF. This analysis offers a framework for a precision medicine approach for IPF.
Divergent observations suggest that genetic factors contribute to the susceptibility to or clinical course of idiopathic pulmonary fibrosis. To determine whether there is an association between the major histocompatibility (HLA) system and idiopathic pulmonary fibrosis, the distribution of 35 antigens of HLA loci A and B was determined among 33 white patients with idiopathic pulmonary fibrosis and 329 healthy white control subjects. Although certain antigens tended to be more prevalent among patients with idiopathic pulmonary fibrosis compared with control subjects, there were no significant differences in the phenotype frequencies of the HLA-A and HLA-B antigens between these 2 groups. Thus, although subtle associations may exist between the HLA loci and idiopathic pulmonary fibrosis, these results indicate that antigens of the HLA-A and HLA-B loci are not linked with major risk factors in this disease.
18 patients with idiopathic pulmonary fibrosis were studied to determine if they had morphologic evidence of small airways disease and if physiologic testing could predict morphologic findings. In the presence of normal airway function by standard physiologic studies (forced expiratory volume in 1 s/forced vital capacity and airway resistance by plethysmography), dynamic compliance, maximum expiratory flow-volume curves, and maximum flowstatic recoil curves were measured to detect physiologic alterations consistent with small airways abnormalities. These physiologic data were then compared with estimates of small airways diameter made in lung biopsy specimens.94% (17 of 18) of the patients had peribronchiolar fibrosis or peribronchiolar inflammation or bronchiolitis. 67% (12 of 18) had an overall estimate of small airways diameter of "narrowed," whereas 33% (6 of 18) had airways that overall were "not narrowed." 59% (10 of 17) had frequency-dependent dynamic compliance, 50% (9 of 18) had abnormal maximum expiratory flow-volume curves, and 39% (7 of 18) had abnormal maximum flow-static recoil curves. Comparisons between morphologic and physiologic data revealed a significant correlation between the results of dynamic compliance and the overall estimate of small airways diameter (P = 0.001), and the results of maximum flow-volume curves and the overall estimate of small airways diameter (P = 0.009); there was no significant correlation between the results of maximum flow-static recoil curves and the overall estimate of small airways diameter (P = 0.1). THE RESULTS OF THIS STUDY SUGGEST THAT: (a) idiopathic pulmonary fibrosis is a disease of small airways as well as alveoli; (b) dynamic compliance and the maximum expiratory flow-volume curve can predict the overall status of small airways diameter in idiopathic pulmonary fibrosis; and (c) whereas the maximum flowstatic recoil curve predicts the overall estimate of small airways diameter in most patients with this disease, it is the least sensitive of these three monitors of small airways.
A model for pulmonary fibrosis in the rat has been developed using intratracheal administration of bleomycin. The histopathologic features of the reaction are similar to those reported in the hamster model. Increases in vascular permeability are seen in the lung within 24 hours and persist over a 2-month period. Extractable collagen, as measured by hydroxyproline, increases during this time by a factor greater than 1.5 times the reference control values of normal lung. During this same period, a prominent eosinophilia develops. The continued treatment of bleomycin-injected rats with indomethacin markedly diminishes the amount of extractable lung collagen at 60 days and the histopathologic evidence of pulmonary fibrosis. The eosinophilia over the first 3 weeks is also markedly suppressed. Less dramatic effects were seen with the permeability changes. These findings indicate that the rat is a reliable and useful model for the study of blemoycin-induced pulmonary fibrosis and that treatment with indomethacin ameliorates the lung changes.
HLA antigens were determined in 37 patients with asbestosis and 37 matched controls with equivalent asbestos exposure but no pulmonary fibrosis. All had worked in the same textile factory. No significant differences in the prevalence of antigens were found between the two groups or between either group and controls who had not been exposed to asbestos. When the data were combined with findings from other pilot studies the previously suggested association between asbestosis and HLA-B27 was not confirmed. Subjects who were positive for HLA-B12 tended also to have advanced radiographic fibrosis. Asbestos workers without pulmonary fibrosis had an unexpectedly high frequency of HLA-BW5, which might indicate that this antigen protects against the development of pulmonary fibrosis.
6 autopsy lungs with interstitial pulmonary fibrosis were subjected to comparative angiographical and morphological investigations of bronchial arteries. During the final stage of interstitial pulmonary fibrosis, bronchial arteries were increased in number, and so were their anastomoses with pulmonary arteries. Extensive formation of broncho-pulmoary anastomosis as well as proliferation and formation of new bronchial arteries, is associated with interstitial chronic inflammation and fibrosis in the lung. The findings explain functional interconnections between the vessels of the systemic and the pulmonary circulations by direct artery-to-artery anastomoses, with a negative influence on pulmonary hypertension.
Idiopathic pulmonary fibrosis is a fatal disorder that starts as an alveolitis and progresses to interstitial fibrosis. Correlative morphologic, physiologic, and biochemical studies in 29 patients have shown that the inflammatory process in best followed by serial bronchoalveolar lavage and 67 Ga citrate scanning, and the fibrotic process is best followed by quantitation of the exercise-induced drop in arterial oxygen tension per unit of oxygen consumed. Although biopsies in idiopathic pulmonary fibrosis seem to show increased amounts of fibrotic tissue, biochemical studies suggest that the disease is probably one of collagen rearrangement rather than collagen increase. Perhaps becasue of this, peripheral lymphocytes of these patients recognize collagen as "non-self" and, when exposed to it in vitro, produce lymphokines and cell lysis. The fibrotic process is probably irreversible, but the inflammatory and immune processes that cause it may be amenable to therapy if diagnosed early.
The universal features of the histopathology of fibrotic lung disease are derangement of parenchymal collagen and infiltration of the parenchyma with chronic inflammatory cells. To determine if this cellular reaction might be associated with autoimmunity to a consitituent of the alveolar interstitium, peripheral blood lymphocytes were exposed to human type I collagen in vitro and evaluated for the production of migration inhibition factor and cytotoxicity. Data from 18 patients with idiopathic pulmonary fibrosis, 8 patients with pulmonary fibrosis other than idiopathic pulmonary fibrosis, 12 patients with nonfibrotic lung disease, and 9 normals demonstrated that circulating lymphocytes from more than 94% of patients with fibrotic lung disease take part in processes where the recognition of collagen results in migration inhibition factor production and lysis of collagen-coated sheep red blood cells. These collagen-induced cell-mediated phenomena are obviated with human T-lymphocyte antiserum. Collagen-induced migration inhibition factor production and cytotoxicity were found in less than 20% of patients with nonfibrotic disease and were not found in normals. Qualitatively, there was no organ (lung, skin) or species (human, rabbit) collagen specificity in these assays, but human lung alpha 2 chains were recognized more often than alpha 1(I) chains. Circulating lymphocytes from patients with fibrotic disease are present in a normal T to B ratio. These lymphocytes did not incorporate [3H]thymidine when exposed to collagen but did when exposed to T-cell mitogens. These in vitro observations suggest that circulating T-lymphocytes and lung collagen may be intimately associated in the pathogenesis of human fibrotic lung disease.