Biomedicines. 2024 Jun 3;12(6):1246. doi: 10.3390/biomedicines12061246.

ABSTRACT

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a type of interstitial lung disease characterized by unknown causes and a poor prognosis. Recent research indicates that age-related mechanisms, such as cellular senescence, may play a role in the development of this condition. However, the relationship between cellular senescence and clinical outcomes in IPF remains uncertain.

METHODS: Data from the GSE70867 database were meticulously analyzed in this study. The research employed differential expression analysis, as well as univariate and multivariate Cox regression analysis, to pinpoint senescence-related genes (SRGs) linked to prognosis and construct a prognostic risk model. The model's clinical relevance and its connection to potential biological processes were systematically assessed in training and testing datasets. Additionally, the expression location of prognosis-related SRGs was identified through immunohistochemical staining, and the correlation between SRGs and immune cell infiltration was deduced using the GSE28221 dataset.

RESULT: The prognostic risk model was constructed based on five SRGs (cellular communication network factor 1, CYR61, stratifin, SFN, megakaryocyte-associated tyrosine kinase, MATK, C-X-C motif chemokine ligand 1, CXCL1, LIM domain, and actin binding 1, LIMA1). Both Kaplan-Meier (KM) curves (p = 0.005) and time-dependent receiver operating characteristic (ROC) analysis affirmed the predictive accuracy of this model in testing datasets, with respective areas under the ROC curve at 1-, 2-, and 3-years being 0.721, 0.802, and 0.739. Furthermore, qRT-RCR analysis and immunohistochemical staining verify the differential expression of SRGs in IPF samples and controls. Moreover, patients in the high-risk group contained higher infiltration levels of neutrophils, eosinophils, and M1 macrophages in BALF, which appeared to be independent indicators of poor prognosis in IPF patients.

CONCLUSION: Our research reveals the effectiveness of the 5 SRGs model in BALF for risk stratification and prognosis prediction in IPF patients, providing new insights into the immune infiltration of IPF progression.

PMID:38927453 | DOI:10.3390/biomedicines12061246

Cell Death Differ. 2024 Jun 26. doi: 10.1038/s41418-024-01333-2. Online ahead of print.

ABSTRACT

Cellular senescence, a hallmark of aging, is pathogenically linked to the development of aging-related diseases. This study demonstrates that FRMD6, an upstream component of the Hippo/YAP signaling cascade, is a key regulator of senescence. Proteomic analysis revealed that FRMD6 is upregulated in senescent IMR90 fibroblasts under various senescence-inducing conditions. Silencing FRMD6 mitigated the senescence of IMR90 cells, suggesting its requirement in senescence. Conversely, the overexpression of FRMD6 alone induced senescence in cells and in lung tissue, establishing a causal link. The elevated FRMD6 levels correlated well with increased levels of the inhibitory phosphorylated YAP/TAZ. We identified cellular communication network factor 3 (CCN3), a key component of the senescence-associated secretory phenotype regulated by YAP, whose administration attenuated FRMD6-induced senescence in a dose-dependent manner. Mechanistically, FRMD6 interacted with and activated MST kinase, which led to YAP/TAZ inactivation. The expression of FRMD6 was regulated by the p53 and SMAD transcription factors in senescent cells. Accordingly, the expression of FRMD6 was upregulated by TGF-β treatment that activates those transcription factors. In TGF-β-treated IMR90 cells, FRMD6 mainly segregated with p21, a senescence marker, but rarely segregated with α-SMA, a myofibroblast marker, which suggests that FRMD6 has a role in directing cells towards senescence. Similarly, in TGF-β-enriched environments, such as fibroblastic foci (FF) from patients with idiopathic pulmonary fibrosis, FRMD6 co-localized with p16 in FF lining cells, while it was rarely detected in α-SMA-positive myofibroblasts that are abundant in FF. In sum, this study identifies FRMD6 as a novel regulator of senescence and elucidates the contribution of the FRMD6-Hippo/YAP-CCN3 axis to senescence.

PMID:38926528 | DOI:10.1038/s41418-024-01333-2

Sci Rep. 2024 Jun 26;14(1):14792. doi: 10.1038/s41598-024-65030-3.

ABSTRACT

Idiopathic Pulmonary Fibrosis (IPF) is a debilitating and fatal lung disease characterized by the excessive formation of scar tissue and decline of lung function. Despite extensive research, only two FDA-approved drugs exist for IPF, with limited efficacy and relevant side effects. Thus, there is an urgent need for new effective therapies, whose discovery strongly relies on IPF animal models. Despite some limitations, the Bleomycin (BLM)-induced lung fibrosis mouse model is widely used for antifibrotic drug discovery and for investigating disease pathogenesis. The initial acute inflammation triggered by BLM instillation and the spontaneous fibrosis resolution that occurs after 3 weeks are the major drawbacks of this system. In the present study, we applied micro-CT technology to a longer-lasting, triple BLM administration fibrosis mouse model to define the best time-window for Nintedanib (NINT) treatment. Two different treatment regimens were examined, with a daily NINT administration from day 7 to 28 (NINT 7-28), and from day 14 to 28 (NINT 14-28). For the first time, we automatically derived both morphological and functional readouts from longitudinal micro-CT. NINT 14-28 showed significant effects on morphological parameters after just 1 week of treatment, while no modulations of these biomarkers were observed during the preceding 7-14-days period, likely due to persistent inflammation. Micro-CT morphological data evaluated on day 28 were confirmed by lung histology and bronchoalveolar lavage fluid (BALF) cells; Once again, the NINT 7-21 regimen did not provide substantial benefits over the NINT 14-28. Interestingly, both NINT treatments failed to improve micro-CT-derived functional parameters. Altogether, our findings support the need for optimized protocols in preclinical studies to expedite the drug discovery process for antifibrotic agents. This study represents a significant advancement in pulmonary fibrosis animal modeling and antifibrotic treatment understanding, with the potential for improved translatability through the concurrent structural-functional analysis offered by longitudinal micro-CT.

PMID:38926490 | DOI:10.1038/s41598-024-65030-3

Thorax. 2024 Jun 26:thorax-2024-222011. doi: 10.1136/thorax-2024-222011. Online ahead of print.

NO ABSTRACT

PMID:38925980 | DOI:10.1136/thorax-2024-222011

Am J Respir Crit Care Med. 2024 Jun 26. doi: 10.1164/rccm.202401-0078OC. Online ahead of print.

ABSTRACT

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

PMID:38924775 | DOI:10.1164/rccm.202401-0078OC

Clin Respir J. 2024 Jun;18(6):e13797. doi: 10.1111/crj.13797.

NO ABSTRACT

PMID:38923707 | DOI:10.1111/crj.13797

J Steroid Biochem Mol Biol. 2024 Jun 23:106560. doi: 10.1016/j.jsbmb.2024.106560. Online ahead of print.

ABSTRACT

Idiopathic pulmonary fibrosis (IPF) is a debilitating and progressive lung disease with an unknown cause that has few treatment options. 18β-Glycyrrhetinic acid (18β-GA) is the main bioactive component in licorice, exhibiting anti-inflammatory and antioxidant effects, while also holding certain application value in the metabolism and regulation of steroids. In this study, we demonstrated that 18β-GA effectively alleviates bleomycin (BLM)-induced IPF by inhibiting the TGF-β1/JAK2/STAT3 signaling axis. In vivo experiments demonstrate that 18β-GA significantly attenuates pulmonary fibrosis progression by reducing lung inflammation, improving lung function, and decreasing collagen deposition. In vitro experiments reveal that 18β-GA inhibits the activation and migration of TGF-β1-induced fibroblasts. Furthermore, it regulates the expression of vimentin, N-cadherin and E-cadherin proteins, thereby inhibiting TGF-β1-induced epithelial-mesenchymal transition (EMT) in lung alveolar epithelial cells. Mechanistically, 18β-GA ameliorates pulmonary fibrosis by modulating the TGF-β1/JAK2/STAT3 signaling pathway in activated fibroblasts. Taken together, our findings demonstrate the potential and underlying mechanisms of 18β-GA in ameliorating IPF, emphasizing its potential as a novel therapeutic drug for the treatment of this devastating disease.

PMID:38917955 | DOI:10.1016/j.jsbmb.2024.106560

bioRxiv [Preprint]. 2024 Jun 13:2024.06.12.598694. doi: 10.1101/2024.06.12.598694.

ABSTRACT

Idiopathic pulmonary fibrosis is a fatal disease characterized by the TGF-β-dependent activation of lung fibroblasts, leading to excessive deposition of collagen proteins and progressive replacement of healthy lung with scar tissue. We and others have shown that fibroblast activation is supported by metabolic reprogramming, including the upregulation of the de novo synthesis of glycine, the most abundant amino acid found in collagen protein. How fibroblast metabolic reprogramming is regulated downstream of TGF-β is incompletely understood. We and others have shown that TGF-β-mediated activation of the Mechanistic Target of Rapamycin Complex 1 (mTORC1) and downstream upregulation of Activating Transcription Factor 4 (ATF4) promote increased expression of the enzymes required for de novo glycine synthesis; however, whether mTOR and ATF4 regulate other metabolic pathways in lung fibroblasts has not been explored. Here, we used RNA sequencing to determine how both ATF4 and mTOR regulate gene expression in human lung fibroblasts following TGF-β. We found that ATF4 primarily regulates enzymes and transporters involved in amino acid homeostasis as well as aminoacyl-tRNA synthetases. mTOR inhibition resulted not only in the loss of ATF4 target gene expression, but also in the reduced expression of glycolytic enzymes and mitochondrial electron transport chain subunits. Analysis of TGF-β-induced changes in cellular metabolite levels confirmed that ATF4 regulates amino acid homeostasis in lung fibroblasts while mTOR also regulates glycolytic and TCA cycle metabolites. We further analyzed publicly available single cell RNAseq data sets and found increased expression of ATF4 and mTOR metabolic targets in pathologic fibroblast populations from the lungs of IPF patients. Our results provide insight into the mechanisms of metabolic reprogramming in lung fibroblasts and highlight novel ATF4 and mTOR-dependent pathways that may be targeted to inhibit fibrotic processes.

PMID:38915485 | PMC:PMC11195155 | DOI:10.1101/2024.06.12.598694

Front Cell Dev Biol. 2024 Jun 10;12:1416325. doi: 10.3389/fcell.2024.1416325. eCollection 2024.

ABSTRACT

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and irreversible interstitial lung disease with a prognosis worse than lung cancer. It is a fatal lung disease with largely unknown etiology and pathogenesis, and no effective therapeutic drugs render its treatment largely unsuccessful. With continuous in-depth research efforts, the epigenetic mechanisms in IPF pathogenesis have been further discovered and concerned. As a widely studied mechanism of epigenetic modification, DNA methylation is primarily facilitated by DNA methyltransferases (DNMTs), resulting in the addition of a methyl group to the fifth carbon position of the cytosine base, leading to the formation of 5-methylcytosine (5-mC). Dysregulation of DNA methylation is intricately associated with the advancement of respiratory disorders. Recently, the role of DNA methylation in IPF pathogenesis has also received considerable attention. DNA methylation patterns include methylation modification and demethylation modification and regulate a range of essential biological functions through gene expression regulation. The Ten-Eleven-Translocation (TET) family of DNA dioxygenases is crucial in facilitating active DNA demethylation through the enzymatic conversion of the modified genomic base 5-mC to 5-hydroxymethylcytosine (5-hmC). TET2, a member of TET proteins, is involved in lung inflammation, and its protein expression is downregulated in the lungs and alveolar epithelial type II cells of IPF patients. This review summarizes the current knowledge of pathologic features and DNA methylation mechanisms of pulmonary fibrosis, focusing on the critical roles of abnormal DNA methylation patterns, DNMTs, and TET proteins in impacting IPF pathogenesis. Researching DNA methylation will enchance comprehension of the fundamental mechanisms involved in IPF pathology and provide novel diagnostic biomarkers and therapeutic targets for pulmonary fibrosis based on the studies involving epigenetic mechanisms.

PMID:38915445 | PMC:PMC11194555 | DOI:10.3389/fcell.2024.1416325

Am J Respir Crit Care Med. 2024 Jun 24. doi: 10.1164/rccm.202402-0339OC. Online ahead of print.

ABSTRACT

Rationale: Idiopathic pulmonary fibrosis (IPF) causes irreversible fibrosis of the lung parenchyma. While antifibrotic therapy can slow IPF progression, treatment response is variable. There exists a critical need to develop a precision medicine approach to IPF. Objective: To identify and validate biologically driven molecular endotypes of IPF. Methods: Latent class analysis (LCA) was independently performed in prospectively recruited discovery (n=875) and validation (n=347) cohorts. Twenty-five plasma biomarkers associated with fibrogenesis served as class-defining variables. The association between molecular endotype and 4-year transplant-free survival was tested using multivariable Cox regression adjusted for baseline confounders. Endotype-dependent differential treatment response to future antifibrotic exposure was then assessed in a pooled cohort of patients naïve to antifibrotic therapy at time of biomarker measurement (n=555). Results: LCA independently identified two latent classes in both cohorts (p<0.0001). WAP four-disulfide core domain protein 2 (WFDC2) was the most important determinant of class membership across cohorts. Membership in Class 2 was characterized by higher biomarker concentrations and higher risk of death or transplantation (discovery: HR 2.02 [95% CI 1.64-2.48]; p<0.001; validation: HR 1.95 [1.34-2.82]; p<0.001). In pooled analysis, significant heterogeneity in treatment effect was observed between endotypes (pinteraction=0.030), with a favorable antifibrotic response in Class 2 (HR 0.64 [0.45-0.93]; p=0.018) but not in Class 1 (HR 1.19 [0.77-1.84]; p=0.422). Conclusions: In this multicohort study, we identified two novel molecular endotypes of IPF with divergent clinical outcomes and response to antifibrotics. Pending further validation, these endotypes could enable a precision medicine approach for future IPF clinical trials.

PMID:38913573 | DOI:10.1164/rccm.202402-0339OC

Int J Nanomedicine. 2024 Jun 19;19:6161-6176. doi: 10.2147/IJN.S453739. eCollection 2024.

ABSTRACT

Idiopathic pulmonary fibrosis (IPF) poses a formidable clinical challenge, characterized by the thickening of alveolar septa and the onset of pulmonary fibrosis. The pronounced activation of oxidative stress emerges as a pivotal hallmark of inflammation. Traditional application of exogenous antioxidants proves inadequate in addressing oxidative stress, necessitating exploration into strategies to augment their antioxidant efficacy. Exosomes, nano-sized extracellular vesicles harboring a diverse array of bioactive factors, present as promising carriers with the potential to meet this challenge. Recent attention has been directed towards the clinical applications of exosomes in IPF, fueling the impetus for this comprehensive review. We have compiled fresh insights into the role of exosomes in modulating oxidative stress in IPF and delved into their potential as carriers for regulating endogenous reactive oxygen species generation. This review endeavors to bridge the divide between exosome research and IPF, traversing from bedside to bench. Through the synthesis of recent findings, we propose exosomes as a novel and promising strategy for improving the outcomes of IPF therapy.

PMID:38911503 | PMC:PMC11193999 | DOI:10.2147/IJN.S453739

J Heart Lung Transplant. 2024 Jun 21:S1053-2498(24)01701-7. doi: 10.1016/j.healun.2024.06.009. Online ahead of print.

ABSTRACT

BACKGROUND: Pleuroparenchymal fibroelastosis (PPFE) has no currently available specific treatment. Benefits of lung transplantation (LT) for PPFE are poorly documented.

METHODS: We conducted a nation-wide multicentric retrospective study in patients who underwent lung or heart-lung transplantation for chronic end-stage lung disease secondary to PPFE between 2012 and 2022 in France.

RESULTS: Thirty-one patients were included. At transplantation, median age was 48 years [IQR 35 - 55]. 64.5% were women. Twenty-one (67.7%) had idiopathic PFFE. Sixteen (52%) had bilateral LT, 10 (32%) had single LT, 4 (13%) had lobar transplantation and one (3%) had heart-lung transplantation. Operative mortality was 3.2%. Early mortality (< 90 days or during the first hospitalization) was 32%. Eleven patients (35.5%) underwent reoperation for hemostasis. Eight (30.8%) experienced bronchial complications. Mechanical ventilation time was 10 days [IQR 2-55]. Length of stay in intensive care unit and hospital were 34 [IQR 18-73] and 64 [IQR 36-103] days, respectively. Median survival was 21 months. Post-transplant survival rates after 1, 2, and 5 years were 57.9%, 42.6% and 38.3% respectively. Low albuminemia (p=0.046), FVC (p=0.021), FEV1 (p=0.009) and high emergency lung transplantation (p=0.04) were associated with increased early mortality. Oversized graft tended to be correlated to a higher mortality (p=0.07).

CONCLUSION: LT for PPFE is associated with high post-operative morbi-mortality rates. Patients requiring high emergency lung transplantation with advanced disease, malnutrition, or critical clinical status experienced worse outcomes.

GOV IDENTIFIER: NCT05044390.

PMID:38909712 | DOI:10.1016/j.healun.2024.06.009

Sci Rep. 2024 Jun 22;14(1):14376. doi: 10.1038/s41598-024-64844-5.

ABSTRACT

Idiopathic pulmonary fibrosis (IPF) is believed to be associated with a notable disruption of cellular energy metabolism. By detecting the changes of energy metabolites in the serum of patients with pulmonary fibrosis, we aimed to investigate the diagnostic and prognostic value of energy metabolites in IPF, and further elucidated the mechanism of their involvement in pulmonary fibrosis. Through metabolomics research, it was discovered that the TCA cycle intermediates changed dramatically in IPF patients. In another validation cohort of 55 patients with IPF compared to 19 healthy controls, it was found that succinate, an intermediate product of TCA cycle, has diagnostic and prognostic value in IPF. The cut-off levels of serum succinate were 98.36 μM for distinguishing IPF from healthy controls (sensitivity, 83.64%; specificity, 63.16%; likelihood ratio, 2.27, respectively). Moreover, a high serum succinate level was independently associated with higher rates of disease progression (OR 13.087, 95%CI (2.819-60.761)) and mortality (HR 3.418, 95% CI (1.308-8.927)). In addition, accumulation of succinate and increased expression of the succinate receptor GPR91 were found in both IPF patients and BLM mouse models of pulmonary fibrosis. Reducing succinate accumulation in BLM mice alleviated pulmonary fibrosis and 21d mortality, while exogenous administration of succinate can aggravate pulmonary fibrosis in BLM mice. Furthermore, GPR91 deficiency protected against lung fibrosis caused by BLM. In vitro, succinate promoted the activation of lung fibroblasts by activating ERK pathway through GPR91. In summary, succinate is a promising biomarker for diagnosis and prognosis of IPF. The accumulation of succinate may promote fibroblast activation through GPR91 and pulmonary fibrosis.

PMID:38909094 | DOI:10.1038/s41598-024-64844-5

Toxicon. 2024 Jun 20:107822. doi: 10.1016/j.toxicon.2024.107822. Online ahead of print.

ABSTRACT

To date there are only pirfenidone (PFD) and nintedanib to be given conditional recommendation in idiopathic pulmonary fibrosis (IPF) therapies with slowing disease progression, but neither has prospectively shown a reduced mortality. It is one of the urgent topics to find effective drugs for pulmonary fibrosis in medicine. Previous studies have demonstrated that microcystin-RR (MC-RR) effectively alleviates bleomycin-induced pulmonary fibrosis, but the mechanism has not been fully elucidated yet. We further conducted a comparison of therapeutic effect on the model animals of pulmonary fibrosis between MC-RR and PFD with histopathology and the expression of the molecular markers involved in differentiation, proliferation and metabolism of myofibroblasts, a major effector cell of tissue fibrosis. The levels of the enzyme molecules for maintaining the stability of interstitial structure were also evaluated. Our results showed that MC-RR and PFD effectively alleviated pulmonary fibrosis in model mice with a decreased signaling and marker molecules associated with myofibroblast differentiation and lung fibrotic lesion. In the meantime, both MC-RR and PFD treatment are beneficial to restore molecular dynamics of interstitial tissue and maintain the stability of interstitial architecture. Unexpectedly, MC-RR, rather than PFD, showed a significant effect on inhibiting PKM2-HIF-1α signaling and reducing the level of p-STAT3. Additionally, MC-RR showed a better inhibition effect on FGFR1 expression. Given that PKM2-HIF-1α and activated STAT3 molecular present a critical role in promoting the proliferation of myofibroblasts, MC-RR as a new strategy for IPF treatment has potential advantage over PFD.

PMID:38908528 | DOI:10.1016/j.toxicon.2024.107822

Respir Res. 2024 Jun 21;25(1):255. doi: 10.1186/s12931-024-02883-2.

ABSTRACT

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a devastating interstitial lung disease (ILD) with a high mortality rate. The antifibrotic medications pirfenidone and nintedanib have been in use since 2014 for this disorder and are associated with improved rate of lung function decline. Less is known about their long-term outcomes outside of the clinical trial context.

METHODS: The Pulmonary Fibrosis Foundation Patient Registry was used for this study. Patients with an IPF diagnosis made within a year of enrollment were included. The treated group was defined as patients receiving either pirfenidone or nintedanib for at least 180 days. The untreated group did not have any record of antifibrotic use. Demographic data, comorbidities, serial lung function, hospitalization, and vital status data were collected from the registry database. The primary outcomes were transplant-free survival, time to first respiratory hospitalization, and time to 10% absolute FVC decline. Time-to-event analyses were performed utilizing Cox proportional hazards models and the log-rank test. Model covariates included age, gender, smoking history, baseline lung function, comorbidities, and oxygen use.

RESULTS: The registry contained 1212 patients with IPF; ultimately 288 patients met inclusion criteria for the treated group, and 101 patients were designated as untreated. Patients treated with antifibrotics were significantly younger (69.8 vs. 72.6 years, p = 0.008) and less likely to have smoked (61.1% ever smokers vs. 72.3% never smokers, p = 0.04). No significant differences were seen in race, gender, comorbidities, or baseline pulmonary function between groups. The primary outcome of transplant-free survival was not significantly different between the two groups (adjusted HR 0.799, 95% CI 0.534-1.197, p = 0.28). Time to respiratory hospitalization was significantly shorter in the treated group (adjusted HR 2.12, 95% CI 1.05-4.30, p = 0.04). No significant difference in time to pulmonary function decline was seen between groups.

CONCLUSIONS: This multicenter study demonstrated 63% of newly diagnosed IPF patients had continuous antifibrotic usage. Antifibrotics were not associated with improved transplant-free survival or pulmonary function change but was associated with an increased hazard of respiratory hospitalization. Future studies should further investigate the role of antifibrotic therapy in clinically important outcomes in real-world patients with IPF and other progressive ILDs.

PMID:38907239 | DOI:10.1186/s12931-024-02883-2

J Adv Res. 2024 Jun 19:S2090-1232(24)00254-6. doi: 10.1016/j.jare.2024.06.017. Online ahead of print.

ABSTRACT

INTRODUCTION: Pulmonary fibrosis (PF) is a fatal fibrotic lung disease without any options to halt disease progression. Feasible evidence suggests that aberrant metabolism of amino acids may play a role in the pathoetiology of PF. However, the exact impact of kynurenine (Kyn), a metabolite derived from tryptophan (Trp) on PF is yet to be addressed.

OBJECTIVES: This study aims to elucidate the role of kynurenine in both the onset and advancement of PF.

METHODS: Liquid chromatography-tandem mass spectrometry was employed to assess Kyn levels in patients with idiopathic PF and PF associated with Sjögren's syndrome. Additionally, a mouse model of PF induced by bleomycin was utilized to study the impact of Kyn administration. Furthermore, cell models treated with TGF-β1 were used to explore the mechanism by which Kyn inhibits fibroblast functions.

RESULTS: We demonstrated that high levels of Kyn are a clinical feature in both idiopathic PF patients and primary Sjögren syndrome associated PF patients. Further studies illustrated that Kyn served as a braking molecule to suppress fibroblast functionality, thereby protecting mice from bleomycin-induced lung fibrosis. The protective effects depend on AHR, in which Kyn induces AHR nuclear translocation, where it upregulates PTEN expression to blunt TGF-β mediated AKT/mTOR signaling in fibroblasts. However, in fibrotic microenviroment, the expression of AHR is repressed by methyl-CpG-binding domain 2 (MBD2), a reader interpreting the effect of DNA methylation, which results in a significantly reduced sensitivity of Kyn to fibroblasts. Therefore, exogenous administration of Kyn substantially reversed established PF.

CONCLUSION: Our studies not only highlighted a critical role of Trp metabolism in PF pathogenesis, but also provided compelling evidence suggesting that Kyn could serve as a promising metabolite against PF.

PMID:38906325 | DOI:10.1016/j.jare.2024.06.017

Eur J Med Chem. 2024 Jun 17;275:116608. doi: 10.1016/j.ejmech.2024.116608. Online ahead of print.

ABSTRACT

Idiopathic pulmonary fibrosis (IPF) is an interstitial lung disease characterized by a progressive fibrotic phenotype. Immunohistochemical studies on HDAC6 overexpression in IPF lung tissues confirmed that IPF is associated with aberrant HDAC6 activity. We herein developed a series of novel HDAC6 inhibitors that can be used as potential pharmacological tools for IPF treatment. The best-performing derivative H10 showed good selectivity for multiple isoforms of the HDAC family. The structural analysis and structure-activity relationship studies of H10 will contribute to optimizing the binding mode of the new molecules. The pharmacological mechanism of H10 to inhibit pulmonary fibrosis was validated, and its ability to inhibit the IPF phenotype was also demonstrated. Moreover, H10 showed satisfactory metabolic stability. The efficacy of H10 was also determined in a mouse model of bleomycin-induced pulmonary fibrosis. The results highlighted in this paper may provide a reference for the identification of new drug molecules for the treatment of IPF.

PMID:38905805 | DOI:10.1016/j.ejmech.2024.116608

Hum Genomics. 2024 Jun 20;18(1):69. doi: 10.1186/s40246-024-00638-0.

ABSTRACT

BACKGROUND: Single cell RNA sequencing technology (scRNA-seq) has been proven useful in understanding cell-specific disease mechanisms. However, identifying genes of interest remains a key challenge. Pseudo-bulk methods that pool scRNA-seq counts in the same biological replicates have been commonly used to identify differentially expressed genes. However, such methods may lack power due to the limited sample size of scRNA-seq datasets, which can be prohibitively expensive.

RESULTS: Motivated by this, we proposed to use the Bayesian-frequentist hybrid (BFH) framework to increase the power and we showed in simulated scenario, the proposed BFH would be an optimal method when compared with other popular single cell differential expression methods if both FDR and power were considered. As an example, the method was applied to an idiopathic pulmonary fibrosis (IPF) case study.

CONCLUSION: In our IPF example, we demonstrated that with a proper informative prior, the BFH approach identified more genes of interest. Furthermore, these genes were reasonable based on the current knowledge of IPF. Thus, the BFH offers a unique and flexible framework for future scRNA-seq analyses.

PMID:38902839 | DOI:10.1186/s40246-024-00638-0

JCI Insight. 2024 Jun 20:e171162. doi: 10.1172/jci.insight.171162. Online ahead of print.

ABSTRACT

Pathological deposition and crosslinking of collagen type I by activated myofibroblasts drives progressive tissue fibrosis. Therapies that inhibit collagen synthesis have potential as anti-fibrotic agents. We identify the collagen chaperone cyclophilin B as a major cellular target of the natural product sanglifehrin A (SfA) using photo-affinity labeling and chemical proteomics. Mechanistically, SfA inhibits and induces the secretion of cyclophilin B from the endoplasmic reticulum (ER) and prevents TGF-β1-activated myofibroblasts from synthesizing and secreting collagen type I in vitro, without inducing ER stress, affecting collagen type I mRNA transcription, myofibroblast migration, contractility, or TGF-β1 signaling. In vivo, SfA induced cyclophilin B secretion in preclinical models of fibrosis, thereby inhibiting collagen synthesis from fibrotic fibroblasts and mitigating the development of lung and skin fibrosis in mice. Ex vivo, SfA induces cyclophilin B secretion and inhibits collagen type I secretion from fibrotic human lung fibroblasts and samples from patients with idiopathic pulmonary fibrosis (IPF). Taken together, we provide chemical, molecular, functional, and translational evidence for demonstrating direct anti-fibrotic activities of SfA in preclinical and human ex vivo fibrotic models. Our results identify the cellular target of SfA, the collagen chaperone cyclophilin B, as a mechanistic target for the treatment of organ fibrosis.

PMID:38900587 | DOI:10.1172/jci.insight.171162

Mol Pharm. 2024 Jun 20. doi: 10.1021/acs.molpharmaceut.4c00405. Online ahead of print.

ABSTRACT

Early detection of pulmonary fibrosis is a critical yet insufficiently met clinical necessity. This study evaluated the effectiveness of FAPI-LM3, a 68Ga-radiolabeled heterobivalent molecular probe that targets fibroblast activating protein (FAP) and somatostatin receptor 2 (SSTR2), in the early detection of pulmonary fibrosis, leveraging its potential for early disease identification. A bleomycin-induced early pulmonary fibrosis model was established in C57BL/6 mice for 7 days. FAP and SSTR2 expression levels were quantitatively assessed in human idiopathic pulmonary fibrosis lung tissue samples and bleomycin-treated mouse lung tissues by using western blotting, real-time quantitative PCR (RT-qPCR), and immunofluorescence techniques. The diagnostic performance of FAPI-LM3 was investigated by synthesizing monomeric radiotracers 68Ga-FAPI-46 and 68Ga-DOTA-LM3 alongside the heterobivalent probe 68Ga-FAPI-LM3. These imaging radiopharmaceuticals were used in small-animal PET to compare their uptake in fibrotic and normal lung tissues. Results indicated significant upregulation of FAP and SSTR2 at both RNA and protein levels in fibrotic lung tissues compared with that in normal controls. PET imaging demonstrated significantly enhanced uptake of the 68Ga-FAPI-LM3 probe in fibrotic lung tissues, with superior visual effects compared to monomeric tracers. At 60 min postinjection, early stage fibrotic tissues (day 7) demonstrated low-to-medium uptake of monomeric probes, including 68Ga-DOTA-LM3 (0.45 ± 0.04% ID/g) and 68Ga-FAPI-46 (0.78 ± 0.09% ID/g), whereas the uptake of the heterobivalent probe 68Ga-FAPI-LM3 (1.90 ± 0.10% ID/g) was significantly higher in fibrotic lesions than in normal lung tissue. Blockade experiments confirmed the specificity of 68Ga-FAPI-LM3 uptake, which was attributed to synergistic targeting of FAP and SSTR2. This study demonstrates the potential of 68Ga-FAPI-LM3 for early pulmonary fibrosis detection via molecular imaging, offering significant benefits over monomeric tracers 68Ga-FAPI-46 and 68Ga-DOTA-LM3. This strategy offers new possibilities for noninvasive and precise early detection of pulmonary fibrosis.

PMID:38899595 | DOI:10.1021/acs.molpharmaceut.4c00405