Lactate accumulation induced by Akt2-PDK1 signaling promotes pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive disease with an abnormal accumulation of fibrotic tissue in the lung parenchyma and elevated glycolysis level in associated cells without effective therapy options. Lactate accumulation in pulmonary fibrotic tissue is a significant factor aggravating IPF development, but the main mechanism regulating glycolysis needs further investigation. In this study, lung fibrosis model was induced by bleomycin (BLM) intratracheally in female C57BL/6 mice. The changes of lactate level and fibrotic markers were detected. For in vitro studies, cell lines of alveolar epithelial cell and lung fibroblast cell were stimulated with TGF-β1 and BLM respectively, to detect changes in their fibrotic properties. The function of lactate accumulation on facilitating fibrosis was verified. We demonstrated that BLM-induced pulmonary fibrosis is accompanied by lactate accumulation owing to glycolysis upregulation. Significantly high PDK1 expression in lung fibrotic tissue promotes glycolysis. Moreover, PDK1 stimulated trans-differentiation of lung fibroblasts and epithelial-mesenchymal transition (EMT) of alveolar epithelial cells. Furthermore, phosphorylated Akt2 activated PDK1 to cause pulmonary fibrosis and inhibitors of Akt2 and PDK1 could suppress fibrotic process. This study is the first to consider PDK1 facilitated lactate accumulation through glycolysis as a vital factor in pulmonary fibrosis and could be initiated by Akt2. We concluded that the pro-fibrotic properties of PDK1 are associated with Akt2 phosphorylation and thus provide new potential therapeutic targets for pulmonary fibrosis.

Buyang Huanwu decoction ameliorates bleomycin-induced pulmonary fibrosis in rats by attenuating the apoptosis of alveolar type II epithelial cells mediated by endoplasmic reticulum stress

ETHNOPHARMACOLOGICAL RELEVANCE

According to the theory of traditional Chinese medicine, the pathogenesis of idiopathic pulmonary fibrosis (IPF) can be attributed to qi deficiency and blood stasis. Buyang Huanwu decoction (BHD), a representative Chinese herbal prescription for qi deficiency and blood stasis syndrome, is widely used to treat IPF in clinical practice. However, its potential mechanisms against IPF remain unclear.

AIMS OF THE STUDY

This study was carried out to explore the therapeutic effects and underlying mechanisms of BHD on bleomycin (BLM)-induced pulmonary fibrosis in rats.

MATERIALS AND METHODS

UPLC-MS/MS method was performed to identify the quality of BHD used in this study. Concurrently, a IPF rat model was established by single intratracheal injection of BLM. Pulmonary function test, H&E staining, Masson staining, hydroxyproline assay were conducted to evaluate the therapeutic effects of BHD on BLM-induced pulmonary fibrosis in rats, and the regulatory effect of BHD on endoplasmic reticulum stress (ERS)-mediated alveolar type II epithelial cells (AEC2s) apoptosis in rats was further investigated by TUNEL staining, Western blot, real-time fluorescence quantitative PCR and immunofluorescence co-staining to reveal the potential mechanisms of BHD against IPF.

RESULTS

The UPLC-MS/MS analysis showed that the BHD we used complied with the relevant quality control standards. The data from animal experiments confirmed that BHD administration ameliorated BLM-induced pulmonary function decline, lung fibrotic pathological changes and collagen deposition in rats. Further mechanism study revealed that BHD increased the Bcl-2 protein expression, decreased the Bax protein expression and inhibited the cleavage of CASP3 via suppressing the activation of PERK-ATF4-CHOP pathway under continuous ERS, thereby alleviating BLM-induced AEC2s apoptosis of rats.

CONCLUSION

This study demonstrated that BHD ameliorated BLM-induced pulmonary fibrosis in rats by suppressing ERS-mediated AEC2s apoptosis. Our findings can provide some fundamental research basis for the clinical application of BHD in the treatment of IPF.

Amifostine ameliorates bleomycin-induced murine pulmonary fibrosis via NAD+/SIRT1/AMPK pathway-mediated effects on mitochondrial function and cellular metabolism

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a devastating chronic lung disease characterized by irreversible scarring of the lung parenchyma. Despite various interventions aimed at mitigating several different molecular aspects of the disease, only two drugs with limited clinical efficacy have so far been approved for IPF therapy.

OBJECTIVE

We investigated the therapeutic efficacy of amifostine, a detoxifying drug clinically used for radiation-caused cytotoxicity, in bleomycin-induced murine pulmonary fibrosis.

METHODS

C57BL6/J mice were intratracheally instilled with 3 U/kg of bleomycin. Three doses of amifostine (WR-2721, 200 mg/kg) were administered intraperitoneally on days 1, 3, and 5 after the bleomycin challenge. Bronchoalveolar lavage fluid (BALF) was collected on day 7 and day 21 for the assessment of lung inflammation, metabolites, and fibrotic injury. Human fibroblasts were treated in vitro with transforming growth factor beta 1 (TGF-β1), followed by amifostine (WR-1065, 1-4 µg/mL) treatment. The effects of TGF-β1 and amifostine on the mitochondrial production of reactive oxygen species (ROS) were assessed by live cell imaging of MitoSOX. Cellular metabolism was assessed by the extracellular acidification rate (ECAR), the oxygen consumption rate (OCR), and the concentrations of various energy-related metabolites as measured by mass spectrum (MS). Western blot analysis was performed to investigate the effect of amifostine on sirtuin 1 (SIRT1) and adenosine monophosphate activated kinase (AMPK).

RESULTS

Three doses of amifostine significantly attenuated lung inflammation and pulmonary fibrosis. Pretreatment and post-treatment of human fibroblast cells with amifostine blocked TGF-β1-induced mitochondrial ROS production and mitochondrial dysfunction in human fibroblast cells. Further, treatment of fibroblasts with TGF-β1 shifted energy metabolism away from mitochondrial oxidative phosphorylation (OXPHOS) and towards glycolysis, as observed by an altered metabolite profile including a decreased ratio of NAD + /NADH and increased lactate concentration. Treatment with amifostine significantly restored energy metabolism and activated SIRT1, which in turn activated AMPK. The activation of AMPK was required to mediate the effects of amifostine on mitochondrial homeostasis and pulmonary fibrosis. This study provides evidence that repurposing of the clinically used drug amifostine may have therapeutic applications for IPF treatment.

CONCLUSION

Amifostine inhibits bleomycin-induced pulmonary fibrosis by restoring mitochondrial function and cellular metabolism.

The use of cultured human alveolar basal cells to mimic honeycomb formation in idiopathic pulmonary fibrosis

BACKGROUND

Honeycomb cysts (HC) within the alveolar region are distinct histopathological features in the lungs of idiopathic pulmonary fibrosis (IPF) patients. HC are lined with a single-or stratified layer of basal cells (BC), or with a bronchiolar-like epithelium composed of basal-, ciliated- and secretory epithelial cells. By using cultured IPF patient-derived alveolar BC, we aimed to establish an in vitro- and in vivo model to mimic HC formation in IPF. We (1) optimized conditions to culture and propagate IPF patient-derived alveolar BC, (2) cultured the cells on an air liquid interface (ALI) or in a three dimensional (3D) organoid model, and (3) investigated the cells` behavior after instillation into bleomycin-challenged mice.

METHODS

Alveolar BC were cultured from peripheral IPF lung tissue and grown on tissue-culture treated plastic, an ALI, or in a 3D organoid model. Furthermore, cells were instilled into bleomycin-challenged NRG mice. Samples were analyzed by TaqMan RT-PCR, immunoblotting, immunocytochemistry/immunofluorescence (ICC/IF), or immunohistochemistry (IHC)/IF. Mann-Whitney tests were performed using GraphPad Prism software.

RESULTS

Cultured alveolar BC showed high expression of canonical basal cell markers (TP63, keratin (KRT)5, KRT14, KRT17), robust proliferation, and wound closure capacity. The cells could be cryopreserved and propagated for up to four passages without a significant loss of basal cell markers. When cultured on an ALI or in a 3D organoid model, alveolar BC differentiated to ciliated- and secretory epithelial cells. When instilled into bleomycin-challenged mice, human alveolar BC cells formed HC-like structures composed of human basal-, and secretory epithelial cells within the mouse parenchyma.

CONCLUSION

IPF patient-derived alveolar BC on an ALI, in 3D organoids or after instillation into bleomycin-challenged mice form HC-like structures that closely resemble HC within the IPF lung. These models therefore represent powerful tools to study honeycomb formation, and its potential therapeutic inhibition in IPF.

Nintedanib solid lipid nanoparticles improve oral bioavailability and ameliorate pulmonary fibrosis in vitro and in vivo models

Nintedanib (NIN) and pirfenidone are the only approved drugs for the treatment of Idiopathic Pulmonary Fibrosis (IPF). However, NIN and pirfenidone have low oral bioavailability and limited therapeutic potential, requiring higher dosages to increase their efficacy, which causes significant liver and gastrointestinal toxicities. In this study, we aimed to develop nintedanib-loaded solid lipid nanoparticles (NIN-SLN) to improve the oral bioavailability and therapeutic potential against TGF-β-induced differentiation in IPF fibroblasts and bleomycin (BLM)-induced lung fibrosis in rat models. NIN-SLN was prepared using a double-emulsification method and characterization studies (Particle size, zeta potential, entrapment efficiency and other parameters) were performed using various techniques. NIN-SLN treatment significantly (p < 0.001) downregulated α-SMA and COL3A1 expression in TGF-β stimulated DHLF and LL29 cells. NIN-SLN showed a 2.87-fold increase in the bioavailability of NIN and also improved the NIN levels in lung tissues compared to NIN alone. Pharmacodynamic investigation revealed that NIN-SLN (50 mg/Kg) treatment significantly attenuated BLM-induced lung fibrosis by inhibiting epithelial-to-mesenchymal-transition (EMT), extracellular matrix remodelling, and collagen deposition compared to free NIN. Additionally, in the BLM model of fibrosis, NIN-SLN greatly improved the BLM-caused pathological changes, attenuated the NIN-induced gastrointestinal abnormalities, and significantly improved the lung functional indices compared to free NIN. Collectively, NIN-SLN could be a promising nanoformulation for the management of pulmonary fibrosis.

H3K18 lactylation promotes the progression of arsenite-related idiopathic pulmonary fibrosis via YTHDF1/m6A/NREP

As epigenetic modifications, lactylation and N6-methyladenosine (m6A) have attracted wide attention. Arsenite is an environmental pollutant that has been proven to induce idiopathic pulmonary fibrosis (IPF). However, the molecular mechanisms of lactylation and m6A methylation are unclear in arsenite-related IPF (As-IPF). In view of the limited understanding of molecular mechanism of m6A and lactylation in As-IPF, MeRIP-seq, RNA-seq and ChIP-seq were analyzed to verify the target gene regulated by m6A and H3K18 lactylation (H3K18la). We found that, for As-IPF, the global levels of m6A, levels of YTHDF1 and m6A-modified neuronal protein 3.1 (NREP) were elevated in alveolar epithelial cells (AECs). The secretion levels of TGF-β1 were increased via YTHDF1/m6A/NREP, which promoted the fibroblast-to-myofibroblast transition (FMT). Further, extracellular lactate from myofibroblasts elevated levels of the global lactylation (Kla) and H3K18la via the lactate monocarboxylate transporter 1 (MCT1), and, in AECs, H3K18la facilitated the transcription of Ythdf1. This report highlights the role of crosstalk between AECs and myofibroblasts via lactylation and m6A and the significance of H3K18la regulation of YTHDF1 in the progression of As-IPF, which may be useful for finding effective therapeutic targets.

Traditional Chinese medicine inspired dual-drugs loaded inhalable nano-therapeutics alleviated idiopathic pulmonary fibrosis by targeting early inflammation and late fibrosis

Idiopathic pulmonary fibrosis (IPF) is a highly debilitating and fatal chronic lung disease that is difficult to cure clinically. IPF is characterized by a gradual decline in lung function, which leads to respiratory failure and severely affects patient quality of life and survival. Oxidative stress and chronic inflammation are believed to be important pathological mechanisms underlying the onset and progression of IPF, and the vicious cycle of NOX4-derived ROS, NLRP3 inflammasome activation, and p38 MAPK in pulmonary fibrogenesis explains the ineffectiveness of single-target or single-drug interventions. In this study, we combined astragaloside IV (AS-IV) and ligustrazine (LIG) based on the fundamental theory of traditional Chinese medicine (TCM) of "tonifying qi and activating blood" and loaded these drugs onto nanoparticles (AS_LIG@PPGC NPs) that were inhalable and could penetrate the mucosal barrier. Our results suggested that inhalation of AS_LIG@PPGC NPs significantly improved bleomycin-induced lung injury and fibrosis by regulating the NOX4-ROS-p38 MAPK and NOX4-NLRP3 pathways to treat and prevent IPF. This study not only demonstrated the superiority, feasibility, and safety of inhalation therapy for IPF intervention but also confirmed that breaking the vicious cycle of ROS and the NLRP3 inflammasome is a promising strategy for the successful treatment of IPF. Moreover, this successful nanoplatform is a good example of the integration of TCM and modern medicine.

Metformin enhanced the effect of pirfenidone on pulmonary fibrosis in mice

BACKGROUND

The aim of the study is to observe the anti-inflammatory and antioxidative stress effects of metformin on bleomycin (BLM)-induced pulmonary fibrosis in mice.

METHODS

Mice with BLM-induced pulmonary fibrosis were treated with pirfenidone, metformin, pirfenidone plus metformin and the NADPH oxidase 4 (NOX4) inhibitor diphenyleneiodonium chloride (DPI). Pathological changes and hydroxyproline (HPO) levels were examined in the lung tissue of mice with pulmonary fibrosis. Superoxide dismutase (SOD) activity and malonaldehyde (MDA) levels in lung tissue were determined.

RESULTS

Compared with pirfenidone, pirfenidone plus metformin could reduce alveolar damage and collagen fibre deposition and alleviate BLM-induced pulmonary fibrosis. Lung HPO levels were significantly lower in the PFD + MET group than in the BLM group (p < 0.05). SOD levels in the lungs of mice were increased in the PFD + MET group than in the BLM group (p < 0.05). Metformin and pirfenidone plus metformin can reduce MDA levels (p < 0.05). Pirfenidone plus metformin could reduce HPO levels, increase SOD levels, and reduce MDA levels in the lungs of mice. There was a significant correlation between the HPO level and the Ashcroft score (r = 0.520, p < 0.001).

CONCLUSION

Metformin enhanced the antifibrotic effects of pirfenidone on BLM-treated mice. Moreover, these findings provide an experimental basis for examining whether metformin can improve the antifibrotic effects of pirfenidone on patients with idiopathic pulmonary fibrosis (IPF). It has broad therapeutic prospects for patients with IPF.

Genetic deficiency of the transcription factor NFAT1 confers protection against fibrogenic responses independent of immune influx

Idiopathic pulmonary fibrosis (IPF) is marked by unremitting matrix deposition and architectural distortion. Multiple profibrotic pathways contribute to the persistent activation of mesenchymal cells (MCs) in fibrosis, highlighting the need to identify and target common signaling pathways. The transcription factor nuclear factor of activated T cells 1 (NFAT1) lies downstream of second messenger calcium signaling and has been recently shown to regulate key profibrotic mediator autotaxin (ATX) in lung MCs. Herein, we investigate the role of NFAT1 in regulating fibroproliferative responses during the development of lung fibrosis. Nfat1-/--deficient mice subjected to bleomycin injury demonstrated improved survival and protection from lung fibrosis and collagen deposition as compared with bleomycin-injured wild-type (WT) mice. Chimera mice, generated by reconstituting bone marrow cells from WT or Nfat1-/- mice into irradiated WT mice (WT→WT and Nfat1-/-→WT), demonstrated no difference in bleomycin-induced fibrosis, suggesting immune influx-independent fibroprotection in Nfat1-/- mice. Examination of lung tissue and flow sorted lineageneg/platelet-derived growth factor receptor alpha (PDGFRα)pos MCs demonstrated decreased MC numbers, proliferation [↓ cyclin D1 and 5-ethynyl-2'-deoxyuridine (EdU) incorporation], myofibroblast differentiation [↓ α-smooth muscle actin (α-SMA)], and survival (↓ Birc5) in Nfat1-/- mice. Nfat1 deficiency abrogated ATX expression in response to bleomycin in vivo and MCs derived from Nfat1-/- mice demonstrated decreased ATX expression and migration in vitro. Human IPF MCs demonstrated constitutive NFAT1 activation, and regulation of ATX in these cells by NFAT1 was confirmed using pharmacological and genetic inhibition. Our findings identify NFAT1 as a critical mediator of profibrotic processes, contributing to dysregulated lung remodeling and suggest its targeting in MCs as a potential therapeutic strategy in IPF.NEW & NOTEWORTHY Idiopathic pulmonary fibrosis (IPF) is a fatal disease with hallmarks of fibroblastic foci and exuberant matrix deposition, unknown etiology, and ineffective therapies. Several profibrotic/proinflammatory pathways are implicated in accelerating tissue remodeling toward a honeycombed end-stage disease. NFAT1 is a transcriptional factor activated in IPF tissues. Nfat1-deficient mice subjected to chronic injury are protected against fibrosis independent of immune influxes, with suppression of profibrotic mesenchymal phenotypes including proliferation, differentiation, resistance to apoptosis, and autotaxin-related migration.

No drug-drug interactions between selective prolyl-tRNA synthetase inhibitor, bersiporocin, and pirfenidone or nintedanib in healthy participants

Bersiporocin, a potent and selective prolyl-tRNA synthetase inhibitor, is expected to show a synergistic effect with pirfenidone or nintedanib in patients with idiopathic pulmonary fibrosis. To validate the combination therapy of bersiporocin with pirfenidone or nintedanib, a randomized, open-label, two-part, one-sequence, three-period, three-treatment study was designed to evaluate the effect of drug-drug interactions (DDI) regarding their pharmacokinetics, safety, and tolerability in healthy participants. In addition, the pharmacokinetic profiles of the newly formulated, enteric-coated bersiporocin tablet were evaluated after single and multiple administrations. The potential effects of cytochrome P450 2D6 (CYP2D6) genotyping on bersiporocin pharmacokinetics and DDI were also explored. In Part 1, participants were sequentially administered a single dose of pirfenidone 600 mg, a single dose of bersiporocin 150 mg followed by multiple doses, and bersiporocin in combination with pirfenidone. In Part 2, participants were sequentially administered a single dose of nintedanib 150 mg, multiple doses of bersiporocin 150 mg, and bersiporocin in combination with nintedanib. Forty-six participants completed the study. There was no significant pharmacokinetic DDI between bersiporocin, and pirfenidone or nintedanib. All adverse events (AEs) were mild to moderate and did not include serious AEs, suggesting bersiporocin alone or in combination therapy were well-tolerated. The newly formulated bersiporocin 150 mg tablet showed a moderate accumulation index. There was no significant difference in the pharmacokinetic profiles after administration of bersiporocin alone or in combination therapy between CYP2D6 phenotypes. In conclusion, there are no significant DDI regarding the pharmacokinetics, safety, and tolerability of bersiporocin administration with pirfenidone or nintedanib.

YTHDC1 delays cellular senescence and pulmonary fibrosis by activating ATR in an m6A-independent manner

Accumulation of DNA damage in the lung induces cellular senescence and promotes age-related diseases such as idiopathic pulmonary fibrosis (IPF). Hence, understanding the mechanistic regulation of DNA damage repair is important for anti-aging therapies and disease control. Here, we identified an m6A-independent role of the RNA-binding protein YTHDC1 in counteracting stress-induced pulmonary senescence and fibrosis. YTHDC1 is primarily expressed in pulmonary alveolar epithelial type 2 (AECII) cells and its AECII expression is significantly decreased in AECIIs during fibrosis. Exogenous overexpression of YTHDC1 alleviates pulmonary senescence and fibrosis independent of its m6A-binding ability, while YTHDC1 deletion enhances disease progression in mice. Mechanistically, YTHDC1 promotes the interaction between TopBP1 and MRE11, thereby activating ATR and facilitating DNA damage repair. These findings reveal a noncanonical function of YTHDC1 in delaying cellular senescence, and suggest that enhancing YTHDC1 expression in the lung could be an effective treatment strategy for pulmonary fibrosis.

Tuftelin1 drives experimental pulmonary fibrosis progression by facilitating stress fiber assembly

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease (ILD) with unknown etiology, characterized by sustained damage repair of epithelial cells and abnormal activation of fibroblasts, the underlying mechanism of the disease remains elusive.

METHODS

To evaluate the role of Tuftelin1 (TUFT1) in IPF and elucidate its molecular mechanism. We investigated the level of TUFT1 in the IPF and bleomycin-induced mouse models and explored the influence of TUFT1 deficiency on pulmonary fibrosis. Additionally, we explored the effect of TUFT1 on the cytoskeleton and illustrated the relationship between stress fiber and pulmonary fibrosis.

RESULTS

Our results demonstrated a significant upregulation of TUFT1 in IPF and the bleomycin (BLM)-induced fibrosis model. Disruption of TUFT1 exerted inhibitory effects on pulmonary fibrosis in both in vivo and in vitro. TUFT1 facilitated the assembly of microfilaments in A549 and MRC-5 cells, with a pronounced association between TUFT1 and Neuronal Wiskott-Aldrich syndrome protein (N-WASP) observed during microfilament formation. TUFT1 can promote the phosphorylation of tyrosine residue 256 (Y256) of the N-WASP (pY256N-WASP). Furthermore, TUFT1 promoted transforming growth factor-β1 (TGF-β1) induced fibroblast activation by increasing nuclear translocation of pY256N-WASP in fibroblasts, while wiskostatin (Wis), an N-WASP inhibitor, suppressed these processes.

CONCLUSIONS

Our findings suggested that TUFT1 plays a critical role in pulmonary fibrosis via its influence on stress fiber, and blockade of TUFT1 effectively reduces pro-fibrotic phenotypes. Pharmacological targeting of the TUFT1-N-WASP axis may represent a promising therapeutic approach for pulmonary fibrosis.

Daphnetin Alleviates Bleomycin-Induced Pulmonary Fibrosis through Inhibition of Epithelial-to-Mesenchymal Transition and IL-17A

Idiopathic pulmonary fibrosis (IPF) is a chronic and refractory interstitial lung disease. Although there is no cure for IPF, the development of drugs with improved efficacy in the treatment of IPF is required. Daphnetin, a natural coumarin derivative, has immunosuppressive, anti-inflammatory, and antioxidant activities. However, its antifibrotic effects have not yet been elucidated. In this study, we investigated the antifibrotic effects of daphnetin on pulmonary fibrosis and the associated molecular mechanism. We examined the effects of daphnetin on splenocytes cultured in Th17 conditions, lung epithelial cells, and a mouse model of bleomycin (BLM)-induced pulmonary fibrosis. We identified that daphnetin inhibited IL-17A production in developing Th17 cells. We also found that daphnetin suppressed epithelial-to-mesenchymal transition (EMT) in TGF-β-treated BEAS2B cells through the regulation of AKT phosphorylation. In BLM-treated mice, the oral administration of daphnetin attenuated lung histopathology and improved lung mechanical functions. Our findings clearly demonstrated that daphnetin inhibited IL-17A and EMT both in vitro and in vivo, thereby protecting against BLM-induced pulmonary fibrosis. Taken together, these results suggest that daphnetin has potent therapeutic effects on lung fibrosis by modulating both Th17 differentiation and the TGF-β signaling pathway, and we thus expect daphnetin to be a drug candidate for the treatment of IPF.

Non-peptidic immunoproteasome β5i-selective inhibitor as potential treatment for idiopathic pulmonary fibrosis: Virtual screening, hit evolution and lead identification

The immunoproteasome has emerged as a potential therapeutic target for idiopathic pulmonary fibrosis (IPF). We report herein our efforts to discover novel non-peptidic immunoproteasome inhibitors as potential treatment for IPF. A structure-based virtual screening was initially performed and the hit compound VS-7 with an IC50 of 9.437 μM against β5i was identified. Hit evolution based on the interaction mode of VS-7 proceeded, and a potent β5i inhibitor 54 (IC50 = 8.463 nM) with favorable subunit-selective profiles was obtained. Compound 54 also imposed significant effects on the release of TNF-α and IL-6, the transcriptional activity of NF-κB, as well as TGF-β1 induced fibroblast proliferation, activation and collagen synthesis. Notably, when administered at 30 mg/kg in a bleomycin-induced IPF mouse model, compound 54 showed anti-fibrotic effects comparable to the clinical drug nintedanib. The results suggest that selective inhibition of immunoproteasome could be an effective approach to treat IPF.

Eupatilin inhibits pulmonary fibrosis by activating Sestrin2/PI3K/Akt/mTOR dependent autophagy pathway

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a progressive chronic inflammatory disease with poor clinical outcomes and ineffective drug treatment options. Eupatilin is a major component extracted from the traditional herbal medicine Artemisia asiatica Nakai. Notably, it was demonstrated to have an anti-fibrosis effect in endometrial fibrosis, vocal fold, and hepatic fibrosis. Its role and mechanism in IPF remain unclear.

METHODS

This study used the TGF-β1-induced human embryonic lung fibroblasts (MRC-5) activation, IPF lung fibroblasts, and bleomycin-induced lung fibrosis mice model. Western blot, immunofluorescence staining, quantitative real time-PCR, hematoxylin and eosin staining, Masson's trichrome staining, and immunohistochemistry were used to evaluate the effects of eupatilin on fibroblast activation, pulmonary fibrosis, and autophagy. The autophagosomes were observed with a transmission electron microscope (TEM). RNA sequencing was used to determine the signaling pathway and key regulator related to autophagy.

RESULTS

Eupatilin significantly decreased the expression of Col1A1, fibronectin, α-SMA, and SQSTM1/p62. In contrast, it increased the expression of LC3B II/I and the number of autophagosomes in TGF-β1 treated MRC-5, IPF lung fibroblasts, and bleomycin-induced lung fibrosis mice model; it also alleviated bleomycin-induced lung fibrosis. The KEGG pathway mapping displayed that PI3K/Akt and Sestrin2 were associated with the enhanced fibrogenic process. Eupatilin suppressed the phosphorylation of PI3K/Akt/mTOR. Autophagy inhibitor 3-methyladenine (3-MA) and Akt activator SC-79 abrogated the anti-fibrotic effect of eupatilin. Sestrin2 expression was also downregulated in TGF-β1 treated lung fibroblasts and lung tissues of the bleomycin-induced pulmonary fibrosis mice model. Furthermore, eupatilin promoted Sestrin2 expression, and the knockdown of Sestrin2 significantly aggravated the degree of fibrosis, increased the phosphorylation of PI3K/Akt/mTOR, and decreased autophagy.

CONCLUSION

These findings indicate that eupatilin ameliorates pulmonary fibrosis through Sestrin2/PI3K/Akt/mTOR-dependent autophagy pathway.

Multi-omics analysis reveals the mechanism of action of ophiopogonin D against pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive lung disease with limited therapeutic strategies. Therefore, there is an urgent need to search for safe and effective drugs to treat this condition. Ophiopogonin D (OP-D), a steroidal saponin compound extracted from ophiopogon, possesses various pharmacological properties, including anti-inflammatory, antioxidant, and antitumor effects. However, the potential pharmacological effect of OP-D on pulmonary fibrosis remains unknown.

PURPOSE

The aim of this study was to investigate whether OP-D can improve pulmonary fibrosis and to explore its mechanism of action.

METHODS

The effect of OP-D on pulmonary fibrosis was investigated in vitro and in vivo using a mouse model of IPF induced by bleomycin and an in vitro model of human embryonic lung fibroblasts induced by transforming growth factor-β1 (TGF-β1). The mechanism of action of OP-D was determined using multi-omics techniques and bioinformatics.

RESULTS

OP-D attenuated epithelial-mesenchymal transition and excessive deposition of extracellular matrix in the lungs, promoted the apoptosis of lung fibroblasts, and blocked the differentiation of lung fibroblasts into myofibroblasts. The multi-omics techniques and bioinformatics analysis revealed that OP-D blocked the AKT/GSK3β pathway, and the combination of a PI3K/AKT inhibitor and OP-D was effective in alleviating pulmonary fibrosis.

CONCLUSION

This study demonstrated for the first time that OP-D can reduce lung inflammation and fibrosis. OP-D is thus a potential new drug for the prevention and treatment of pulmonary fibrosis.

Heterogenous Intrapulmonary Distribution of Aerosolized Model Compounds in Mice with Bleomycin-Induced Pulmonary Fibrosis

Background: A distinctive pathological feature of idiopathic pulmonary fibrosis (IPF) is the aberrant accumulation of extracellular matrix components in the alveoli in abnormal remodeling and reconstruction following scarring of the alveolar structure. The current antifibrotic agents used for IPF therapy frequently result in systemic side effects because these agents are distributed, through the blood, to many different tissues after oral administration. In contrast to oral administration, the intrapulmonary administration of aerosolized drugs is believed to be an efficient method for their direct delivery to the focus sites in the lungs. However, how fibrotic lesions alter the distribution of aerosolized drugs following intrapulmonary administration remains largely unknown. In this study, we evaluate the intrapulmonary distribution characteristics of aerosolized model compounds in mice with bleomycin-induced pulmonary fibrosis through imaging the organs and alveoli. Methods: Aerosolized model compounds were administered to mice with bleomycin-induced pulmonary fibrosis using a Liquid MicroSprayer®. The intrapulmonary distribution characteristics of aerosolized model compounds were evaluated through several imaging techniques, including noninvasive lung imaging using X-ray computed tomography, ex vivo imaging using zoom fluorescence microscopy, frozen tissue section observation, and three-dimensional imaging with tissue-clearing treatment using confocal laser microscopy. Results: In fibrotic lungs, the aerosolized model compounds were heterogeneously distributed. In observations of frozen tissue sections, model compounds were observed only in the fibrotic foci near airless spaces called honeycombs. In three-dimensional imaging of cleared tissue from fibrotic lungs, the area of the model compound in the alveolar space was smaller than in healthy lungs. Conclusion: The intrapulmonary deposition of extracellular matrix associated with pulmonary fibrosis limits the intrapulmonary distribution of aerosolized drugs. The development of delivery systems for antifibrotic agents to improve the distribution characteristics in fibrotic foci is necessary for effective IPF therapy.

Induced pluripotent stem cells modulate the Wnt pathway in the bleomycin-induced model of idiopathic pulmonary fibrosis

BACKGROUND

The Wnt signaling pathway has been implicated in the pathogenesis of fibrotic disorders and malignancies. Hence, we aimed to assess the potential of the induced pluripotent stem cells (IPS) in modulating the expression of the cardinal genes of the Wnt pathway in a mouse model of idiopathic pulmonary fibrosis (IPF).

METHODS

C57Bl/6 mice were randomly divided into three groups of Control, Bleomycin (BLM), and BLM + IPS; the BLM mice received intratracheal instillation of bleomycin, BLM + IPS mice received tail vein injection of IPS cells 48 h post instillation of the BLM; The Control group received Phosphate-buffered saline instead. After 3 weeks, the mice were sacrificed and Histologic assessments including hydroxy proline assay, Hematoxylin and Eosin, and Masson-trichrome staining were performed. The expression of the genes for Wnt, β-Catenin, Lef, Dkk1, and Bmp4 was assessed utilizing specific primers and SYBR green master mix.

RESULTS

Histologic assessments revealed that the fibrotic lesions and inflammation were significantly alleviated in the BLM + IPS group. Besides, the gene expression analyses demonstrated the upregulation of Wnt, β-Catenin, and LEF along with the significant downregulation of the Bmp4 and DKK1 in response to bleomycin treatment; subsequently, it was found that the treatment of the IPF mice with IPS cells results in the downregulation of the Wnt, β-Catenin, and Lef, as well as upregulation of the Dkk1, but not the Bmp4 gene (P values < 0.05).

CONCLUSION

The current study highlights the therapeutic potential of the IPS cells on the IPF mouse model in terms of regulating the aberrant expression of the factors contributing to the Wnt signaling pathway.

Functional Pdgfra fibroblast heterogeneity in normal and fibrotic mouse lung

Aberrant fibroblast function plays a key role in the pathogenesis of idiopathic pulmonary fibrosis, a devastating disease of unrelenting extracellular matrix deposition in response to lung injury. Platelet-derived growth factor α-positive (Pdgfra+) lipofibroblasts (LipoFBs) are essential for lung injury response and maintenance of a functional alveolar stem cell niche. Little is known about the effects of lung injury on LipoFB function. Here, we used single-cell RNA-Seq (scRNA-Seq) technology and PdgfraGFP lineage tracing to generate a transcriptomic profile of Pdgfra+ fibroblasts in normal and injured mouse lungs 14 days after bleomycin exposure, generating 11 unique transcriptomic clusters that segregated according to treatment. While normal and injured LipoFBs shared a common gene signature, injured LipoFBs acquired fibrogenic pathway activity with an attenuation of lipogenic pathways. In a 3D organoid model, injured Pdgfra+ fibroblast-supported organoids were morphologically distinct from those cultured with normal fibroblasts, and scRNA-Seq analysis suggested distinct transcriptomic changes in alveolar epithelia supported by injured Pdgfra+ fibroblasts. In summary, while LipoFBs in injured lung have not migrated from their niche and retain their lipogenic identity, they acquire a potentially reversible fibrogenic profile, which may alter the kinetics of epithelial regeneration and potentially contribute to dysregulated repair, leading to fibrosis.

Inhalation Lenalidomide-Loaded Liposome for Bleomycin-Induced Pulmonary Fibrosis Improvement

Idiopathic pulmonary fibrosis (IPF) is a progressive, fibrotic interstitial lung disease with unclear etiology and increasing prevalence. Pulmonary administration can make the drug directly reach the lung lesion location and reduce systemic toxic and side effects. The effectiveness of lenalidomide (Len) liposomal lung delivery in idiopathic pulmonary fibrosis was investigated. Len liposomes (Len-Lip) were prepared from soybean lecithin, cholesterol (Chol), and medicine in different weight ratios by thin film hydration method. The Len-Lip were spherical in shape with an average size of 226.7 ± 1.389 nm. The liposomes with a higher negative zeta potential of around - 34 mV, which was conducive to improving stability by repelling each other. The drug loading and encapsulation rate were 2.42 ± 0.07% and 85.47 ± 2.42%. Len-Lip had little toxicity at the cellular level and were well taken up by cells. At bleomycin-induced pulmonary fibrosis model mice, inhalation Len-Lip could improve lung function and decrease lung hydroxyproline contents, and alleviate pulmonary fibrosis state. Inhalation Len-Lip provided a reference for the treatment of idiopathic pulmonary fibrosis.

Monoclonal enolase-1 blocking antibody ameliorates pulmonary inflammation and fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a chronic fatal disease with limited therapeutic options. The infiltration of monocytes and fibroblasts into the injured lungs is implicated in IPF. Enolase-1 (ENO1) is a cytosolic glycolytic enzyme which could translocate onto the cell surface and act as a plasminogen receptor to facilitate cell migration via plasmin activation. Our proprietary ENO1 antibody, HL217, was screened for its specific binding to ENO1 and significant inhibition of cell migration and plasmin activation (patent: US9382331B2).

METHODS

In this study, effects of HL217 were evaluated in vivo and in vitro for treating lung fibrosis.

RESULTS

Elevated ENO1 expression was found in fibrotic lungs in human and in bleomycin-treated mice. In the mouse model, HL217 reduced bleomycin-induced lung fibrosis, inflammation, body weight loss, lung weight gain, TGF-β upregulation in bronchial alveolar lavage fluid (BALF), and collagen deposition in lung. Moreover, HL217 reduced the migration of peripheral blood mononuclear cells (PBMC) and the recruitment of myeloid cells into the lungs. In vitro, HL217 significantly reduced cell-associated plasmin activation and cytokines secretion from primary human PBMC and endothelial cells. In primary human lung fibroblasts, HL217 also reduced cell migration and collagen secretion.

CONCLUSIONS

These findings suggest multi-faceted roles of cell surface ENO1 and a potential therapeutic approach for pulmonary fibrosis.

Expression of PD-1/PD-L1 axis in mediastinal lymph nodes and lung tissue of human and experimental lung fibrosis indicates a potential therapeutic target for idiopathic pulmonary fibrosis

BACKGROUND

Mediastinal lymph node enlargement is prevalent in patients with idiopathic pulmonary fibrosis (IPF). Studies investigating whether this phenomenon reflects specific immunologic activation are lacking.

METHODS

Programmed cell death-1 (PD-1)/ programmed cell death ligand-1 (PD-L1) expression in mediastinal lymph nodes and lung tissues was analyzed. PD-1, PD-L1 mRNA expression was measured in tracheobronchial lymph nodes of mice following bleomycin-induced injury on day 14. Finally, the effect of the PD-1 inhibitor, pembrolizumab, in bleomycin-induced pulmonary fibrosis was investigated.

RESULTS

We analyzed mediastinal lymph nodes of thirty-three patients (n = 33, IPF: n = 14, lung cancer: n = 10, concomitant IPF and lung cancer: n = 9) and lung tissues of two hundred nineteen patients (n = 219, IPF: 123, controls: 96). PD-1 expression was increased, while PD-L1 expression was decreased, in mediastinal lymph nodes of patients with IPF compared to lung cancer and in IPF lungs compared to control lungs. Tracheobronchial lymph nodes isolated on day 14 from bleomycin-treated mice exhibited increased size and higher PD-1, PD-L1 mRNA levels compared to saline-treated animals. Pembrolizumab blunted bleomycin-induced lung fibrosis, as indicated by reduction in Ashcroft score and improvement in respiratory mechanics.

CONCLUSIONS

Mediastinal lymph nodes of patients with IPF exhibit differential expression profiles than those of patients with lung cancer indicating distinct immune-mediated pathways regulating fibrogenesis and carcinogenesis. PD-1 expression in mediastinal lymph nodes is in line with lung tissue expression. Lower doses of pembrolizumab might exert antifibrotic effects. Clinical trials aiming to endotype patients based on mediastinal lymph node profiling and accordingly implement targeted therapies such as PD-1 inhibitors are greatly anticipated.

MiR-326-mediated overexpression of NFIB offsets TGF-β induced epithelial to mesenchymal transition and reverses lung fibrosis

Idiopathic Pulmonary Fibrosis (IPF) is a progressively fatal and incurable disease characterized by the loss of alveolar structures, increased epithelial-mesenchymal transition (EMT), and aberrant tissue repair. In this study, we investigated the role of Nuclear Factor I-B (NFIB), a transcription factor critical for lung development and maturation, in IPF. Using both human lung tissue samples from patients with IPF, and a mouse model of lung fibrosis induced by bleomycin, we showed that there was a significant reduction of NFIB both in the lungs of patients and mice with IPF. Furthermore, our in vitro experiments using cultured human lung cells demonstrated that the loss of NFIB was associated with the induction of EMT by transforming growth factor beta (TGF-β). Knockdown of NFIB promoted EMT, while overexpression of NFIB suppressed EMT and attenuated the severity of bleomycin-induced lung fibrosis in mice. Mechanistically, we identified post-translational regulation of NFIB by miR-326, a miRNA with anti-fibrotic effects that is diminished in IPF. Specifically, we showed that miR-326 stabilized and increased the expression of NFIB through its 3'UTR target sites for Human antigen R (HuR). Moreover, treatment of mice with either NFIB plasmid or miR-326 reversed airway collagen deposition and fibrosis. In conclusion, our study emphasizes the critical role of NFIB in lung development and maturation, and its reduction in IPF leading to EMT and loss of alveolar structures. Our study highlights the potential of miR-326 as a therapeutic intervention for IPF. The schema shows the role of NFIB in maintaining the normal epithelial cell characteristics in the lungs and how its reduction leads to a shift towards mesenchymal cell-like features and pulmonary fibrosis. A In normal lungs, NFIB is expressed abundantly in the epithelial cells, which helps in maintaining their shape, cell polarity and adhesion molecules. However, when the lungs are exposed to factors that induce pulmonary fibrosis, such as bleomycin, or TGF-β, the epithelial cells undergo epithelial to mesenchymal transition (EMT), which leads to a decrease in NFIB. B The mesenchymal cells that arise from EMT appear as spindle-shaped with loss of cell junctions, increased cell migration, loss of polarity and expression of markers associated with mesenchymal cells/fibroblasts. C We designed a therapeutic approach that involves exogenous administration of NFIB in the form of overexpression plasmid or microRNA-326. This therapeutic approach decreases the mesenchymal cell phenotype and restores the epithelial cell phenotype, thus preventing the development or progression of pulmonary fibrosis.

Effects of aging on accompanying intermittent hypoxia in a bleomycin-induced pulmonary fibrosis mouse model

BACKGROUND/AIMS

Obstructive sleep apnea (OSA) is prevalent in older patients with idiopathic pulmonary fibrosis (IPF); however, it is underrecognized. OSA is characterized by intermittent hypoxia (IH) and sleep fragmentation. In this study, we evaluated the effects of IH in an older mouse model of bleomycin-induced lung fibrosis.

METHODS

Bleomycin-induced mice (C57BL/6, female) were randomly divided into four groups of young vs. old and room air (RA)-exposed vs. IH-exposed. Mice were exposed to RA or IH (20 cycles/h, FiO2 nadir 7 ± 0.5%, 8 h/day) for four weeks. The mice were sacrificed on day 28, and blood, bronchoalveolar lavage (BAL) fluid, and lung tissue samples were obtained.

RESULTS

The bleomycin-induced IH-exposed (EBI) older group showed more severe inflammation, fibrosis, and oxidative stress than the other groups. The levels of inflammatory cytokines in the serum and BAL fluid increased in the EBI group. Hydroxyproline levels in the lung tissue increased markedly in the EBI group.

CONCLUSION

This study demonstrates the possible harmful impact of OSA in an elderly mouse model of lung fibrosis. This study further suggests that older patients with IPF and OSA may be more of a concern than younger patients with IPF. Further research is required in this area.

Fraxetin alleviates BLM-induced idiopathic pulmonary fibrosis by inhibiting NCOA4-mediated epithelial cell ferroptosis

INTRODUCTION

Idiopathic pulmonary fibrosis (IPF) is a debilitating lung condition with few available treatments. The early driver of wound repair that contributes to IPF has been extensively identified as repetitive alveolar epithelial damage. According to recent reports, IPF is linked to ferroptosis, a unique type of cell death characterized by a fatal buildup of iron and lipid peroxidation.

OBJECTIVE AND METHOD

There is little information on epithelial cells that induce pulmonary fibrosis by going through ferroptosis. In this study, we used bleomycin (BLM) to examine the impact of ferroptosis on IPF in mouse lung epithelial cells (MLE-12).

RESULTS

We discovered that BLM increases ferroptosis in MLE-12. Additionally, we found that NCOA4 is overexpressed and plays a key role in the ferroptosis of epithelial cells throughout the IPF process. Using Molecular docking, we found that Fraxetin, a natural component extracted from Fraxinus rhynchophylla, formed a stable binding to NCOA4. In vitro investigations showed that Fraxetin administration greatly decreased ferroptosis and NCOA4 expression, which in turn lowered the release of inflammatory cytokines.

CONCLUSION

Fraxetin treatment significantly alleviated BLM-induced lung inflammation and fibrosis. Our findings imply that fraxetin possesses inhibitory roles in ferroptosis and can be a potential drug against IPF.