PKM2 promotes pulmonary fibrosis by stabilizing TGF-β1 receptor I and enhancing TGF-β1 signaling

Protein Ubiquitination Modification in Pulmonary Fibrosis

Pulmonary fibrosis (PF) is a chronic, progressive fibrotic interstitial lung disease characterized by a high incidence and mortality rate, which encompasses features, such as diffuse alveolar inflammation, invasive fibroblast activation, and uncontrolled extracellular matrix (ECM) deposition. Beyond the local pathological processes, PF can be better understood in light of interorgan communication networks that are involved in its progression. Notably, pulmonary inflammation can affect cardiovascular, renal, hepatic, and neural functions, highlighting the importance of understanding these systemic interactions. Posttranslational modifications play a crucial role in regulating protein function, localization, stability, and activity. Specifically, protein ubiquitination modifications are involved in PF induced by various stimuli, involving a range of ubiquitin-modifying enzymes and substrates. In this review, we provide an overview of how E3 ubiquitin ligases and deubiquitinating enzymes (DUBs) modulate PF through several signaling pathways, such as TGF-β, Wnt, metabolic activity, aging, ferroptosis, endoplasmic reticulum stress, and inflammatory responses. This perspective includes the role of ubiquitin-proteasome systems in interorgan communication, affecting the progression of PF and related systemic conditions. Additionally, we also summarize the currently available therapeutic compounds targeting protein ubiquitination-related enzymes or ubiquitination substrates for the treatment of PF. Understanding the interplay between ubiquitination and interorgan communication may pave the way for novel therapeutic strategies.

GPR40 activation alleviates pulmonary fibrosis by repressing M2 macrophage polarization through the PKD1/CD36/TGF-β1 pathway

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive interstitial lung disease characterized by complex aetiologies involving the accumulation of inflammatory cells, such as macrophages, in the alveoli. This process is driven by uncontrolled extracellular matrix (ECM) deposition and the development of fibrous connective tissues. Here, we observed that the mRNA expression of Ffar1, the gene encoding G protein-coupled receptor 40 (GPR40), is repressed, while Cd36 is increased in the bronchoalveolar lavage fluid (BALF), which is predominantly composed of alveolar macrophages, of IPF patients. Furthermore, the GPR40 protein was found to be largely adhered to macrophages and was pathologically downregulated in the lungs of bleomycin (BLM)-induced PF model mice (PF mice) compared with those of control mice. Specific knockdown of GPR40 in pulmonary macrophages by adeno-associated virus 9-F4/80-shGPR40 (AAV9-shGPR40) exacerbated the fibrotic phenotype in the PF mice, and activation of GPR40 by its determined agonist compound SC (1,3-dihydroxy-8-methoxy-9H-xanthen-9-one) effectively protected the PF mice from pathological exacerbation. Moreover, Ffar1 or Cd36 gene knockout mouse-based assays were performed to explore the mechanism underlying the regulation of GPR40 activation in pulmonary macrophages with compound SC as a probe. We found that compound SC mitigated pulmonary fibrosis progression by preventing M2 macrophage polarization from exerting profibrotic effects through the GPR40/PKD1/CD36 axis. Our results strongly support the therapeutic potential of targeting intrinsic GPR40 activation in pulmonary macrophages for IPF and highlight the potential of compound SC in treating this disease.

13-Methylpalmatine alleviates bleomycin-induced pulmonary fibrosis by suppressing the ITGA5/TGF-β/Smad signaling pathway

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is an irreversible lung disease for which there is a lack of effective and safe therapeutic drugs. 13-Methylpalmatine (13-Me-PLT) is an active compound from Coptis chinensis, and no study has yet been reported on its pharmacological effects in pulmonary fibrotic diseases. The group has previously demonstrated the antimyocardial fibrosis efficacy of 13-Me-PLT but its effect on pulmonary fibrosis and its potential mechanism has not yet been investigated.

PURPOSE

The present research is designed to clarify the therapeutic potential and mechanism of action of 13-Me-PLT in IPF using a bleomycin (BLM)-induced mouse model of IPF.

METHODS

In vivo, mice were administrated with BLM to establish the IPF model, and IPF mice were treated with 13-Me-PLT (5, 10, and 20 mg/kg) and pirfenidone (PFD, 300 mg/kg) by gavage. In vitro, we employed TGF-β1 (10 ng/ml)-induced MRC5 cells, which were then treated with 13-Me-PLT (5, 10, 20 μM) and PFD (500 μM). High-throughput transcriptome sequencing, molecular dynamics simulations, molecular docking and Surface plasmon resonance (SPR) were employed to elucidate the underlying mechanisms of 13-Me-PLT in mitigating IPF.

RESULT

In vivo experiments showed that 13-Me-PLT significantly ameliorated BLM-induced lung fibrosis in mice. In vitro studies, 13-Me-PLT showed good antifibrotic potential by inhibiting fibroblast differentiation. Transcriptomic analysis of mouse lung tissues identified ITGA5 and TGF-β/Smad signaling pathways as key targets for the antifibrotic effects of 13-Me-PLT. Molecular docking and kinetic analyses further supported these findings. Functional studies involving ITGA5 silencing and overexpression confirmed that 13-Me-PLT down-regulated ITGA5 expression and inhibited the activation of the TGF-β/Smad signaling pathway, confirming its mechanism of action.

CONCLUSION

To our best knowledge, these results provide the first insight that 13-Me-PLT is protective against BLM-induced IPF in mice. Unlike existing antifibrotic drugs, 13-Me-PLT specifically targets the ITGA5/TGF-β/Smad signaling pathway, offering a novel and potentially more effective therapeutic approach. This study not only validates the antifibrotic efficacy of 13-Me-PLT but also elucidates its unique mechanism of action, these findings may provide an opportunity to develop new drugs to treat IPF.

Btbd8 deficiency exacerbates bleomycin-induced pulmonary fibrosis in mice by enhancing myofibroblast accumulation and inflammatory responses

BTBD8 contributes to the pathogenesis of inflammatory bowel disease through regulating intestinal barrier integrity and inflammation. However, its role in idiopathic pulmonary fibrosis (IPF) remains unknown. Here we investigated whether BTBD8 plays a role in bleomycin-induced pulmonary fibrosis. Pulmonary fibrosis was induced in wild-type (WT) and Btbd8 knockout (KO) mice by intratracheal instillation of bleomycin. The mice were sacrificed on day 7 or 12. Subsequently, the progression of bleomycin-induced pulmonary fibrosis was assessed. We found that Btbd8 KO mice are more susceptible to bleomycin-induced pulmonary fibrosis, with more severe body weight loss and pulmonary injury, increased collagen deposition and myofibroblast accumulation. We further demonstrated that BTBD8 functions in pulmonary fibroblasts to suppress the conversion of fibroblasts to myofibroblasts. Moreover, Btbd8 deficiency promotes the infiltration of inflammatory cells and the secretion of pro-inflammatory cytokines in IPF mouse model. These results highlight the critical role of BTBD8 in the pathogenesis of bleomycin-induced pulmonary fibrosis in mice, and suggest that BTBD8 may alleviate bleomycin-induced fibrosis by suppressing the differentiation of fibroblasts to myofibroblast, as well as inflammatory responses.

Daidzein alleviates skin fibrosis by suppressing TGF-β1 signaling pathway via targeting PKM2

Skin fibrosis including keloids, which are characterized including excessive deposition, abnormal proliferation, aggressiveness, and migration of the extracellular matrix of dermal fibroblasts. TGF-β signaling is a classical pro-fibrotic pathway, and it plays a crucial part in the occurrence and progression of skin fibrosis. Daidzein (Dai), an isoflavone compound, has been proved to possess anti-fibrosis effect by TGF-β signaling in various inflammatory and fibrotic diseases. However, little is known about Dai on skin fibrosis. Therefore, we further explored the potential effects and mechanisms of daidzein on skin fibrosis. As expected, Dai suppressed proliferation, migration and activation mouse primary dermal fibroblasts and keloid fibroblasts. Meanwhile, Dai also ameliorated bleomycin-induced skin fibrosis and reduced fibrotic markers of keloid tissues. In addition, Dai could target PKM2 to inhibit TGF-β1/Smad signaling in skin fibrosis. Overall, our research demonstrated that Dai might become a potential therapeutic candidate drug for skin fibrosis.

Identification of glycolysis-related gene signatures for prognosis and therapeutic targeting in idiopathic pulmonary fibrosis

Background

Glycolysis plays a crucial role in fibrosis, but the specific genes involved in glycolysis in idiopathic pulmonary fibrosis (IPF) are not well understood.

Methods

Three IPF gene expression datasets were obtained from the Gene Expression Omnibus (GEO), while glycolysis-related genes were retrieved from the Molecular Signatures Database (MsigDB). Differentially expressed glycolysis-related genes (DEGRGs) were identified using the "limma" R package. Diagnostic glycolysis-related genes (GRGs) were selected through least absolute shrinkage and selection operator (LASSO) regression regression and support vector machine-recursive feature elimination (SVM-RFE). A prognostic signature was developed using LASSO regression, and time-dependent receiver operating characteristic (ROC) curves were generated to evaluate predictive performance. Single-cell RNA sequencing (scRNA-seq) data were analyzed to examine GRG expression across various cell types. Immune infiltration analysis, Gene Set Enrichment Analysis (GSEA), and Gene Set Variation Analysis (GSVA) were performed to elucidate potential molecular mechanisms. A bleomycin (BLM)-induced pulmonary fibrosis mouse model was used for experimental validation via reverse transcription-quantitative polymerase chain reaction (RT-qPCR).

Results

14 GRGs (VCAN, MERTK, FBP2, TPBG, SDC1, AURKA, ARTN, PGP, PLOD2, PKLR, PFKM, DEPDC1, AGRN, CXCR4) were identified as diagnostic markers for IPF, with seven (ARTN, AURKA, DEPDC1, FBP2, MERTK, PFKM, SDC1) forming a prognostic model demonstrating predictive power (AUC: 0.831-0.793). scRNA-seq revealed cell-type-specific GRG expression, particularly in macrophages and fibroblasts. Immune infiltration analysis linked GRGs to imbalanced immune responses. Experimental validation in a bleomycin-induced fibrosis model confirmed the upregulation of GRGs (such as AURKA, CXCR4). Drug prediction identified inhibitors (such as Tozasertib for AURKA, Plerixafor for CXCR4) as potential therapeutic agents.

Conclusion

This study identifies GRGs as potential prognostic biomarkers for IPF and highlights their role in modulating immune responses within the fibrotic lung microenvironment. Notably, AURKA, MERTK, and CXCR4 were associated with pathways linked to fibrosis progression and represent potential therapeutic targets. Our findings provide insights into metabolic reprogramming in IPF and suggest that targeting glycolysis-related pathways may offer novel pharmacological strategies for antifibrotic therapy.

KLF12 Aggravates Angiotensin II-Induced Cardiac Remodeling in Male Mice by Transcriptionally Inhibiting SMAD7

BACKGROUND

Adverse left ventricular remodeling and subsequent heart failure remain a major cause of patient morbidity and mortality worldwide. The KLF family of transcription factors plays crucial roles in heart injury. KLF12 (Krüppel-like factor 12) is a transcription factor that regulates multiple disease processes, although the specific role of KLF12 in cardiac remodeling remains unclear.

METHODS AND RESULTS

In our study, we observed a significant upregulation of KLF12 expression in remodeling hearts. The increased expression of KLF12 primarily originated from cardiac fibroblasts during the fibrotic response induced by angiotensin II. To investigate the effects of KLF12, we performed RNA-seq and found that KLF12 overexpression significantly upregulated the cardiac remodeling associated pathway. Hence, we generated adult mice with cardiac fibroblast-specific overexpression of KLF12 using lentivirus or miRNA (miR-1/133TS) technology. Compared with control mice, KLF12-miR1/133TS transfected mice exhibited exacerbated cardiac remodeling and function. Mechanistically, we discovered that KLF12 directly binds to the promoter of Smad7, leading to the activation of the TGF-β (transforming growth factor beta)-Smad3 pathway.

CONCLUSIONS

In conclusion, KLF12 promoted the development of angiotensin II-induced cardiac remodeling in male mice. Targeting KLF12 may be a promising therapeutic approach to treat cardiac remodeling.

PFKP inhibition protects against pathological cardiac hypertrophy by regulating protein synthesis

Metabolic reprogramming precedes most alterations during pathological cardiac hypertrophy and heart failure (HF). Recent studies have revealed that Phosphofructokinase, platelet (PFKP) has a wealth of metabolic and non-metabolic functions. In this study, we explored the role of PFKP in cardiac hypertrophic growth and HF. The expression level of PFKP was elevated both in pathological cardiac remodeling mouse model challenged by transverse aortic constriction (TAC) surgery and in the neonatal rat cardiomyocytes (NRCMs) stimulated by phenylephrine (PE). In global PFKP knockout (PFKP-KO) mice, cardiac hypertrophy was ameliorated under TAC surgery, while overexpression of PFKP by intravenous injection of adeno-associated virus 9 (AAV9) under the cardiac troponin T (cTnT) promoter worsened myocardial hypertrophy and fibrosis. In NRCMs, small interfering RNA (SiRNA) knockdown or adenovirus (Adv) overexpression of PFKP was employed and the intervention of PFKP showed a similar phenotype. Mechanistically, immunoprecipitation combined with liquid chromatography-tandem mass spectrometry (IP-MS/MS) analysis was used to identify the interacting proteins of PFKP. Eukaryotic translation initiation factor 2 subunit beta (EIF2S2) was identified as the downstream target of PFKP. In the PE-stimulated NRCM hypertrophy model and mouse TAC model, knocking down EIF2S2 after PFKP overexpression reduced the synthesis of new proteins and alleviated the hypertrophy phenotype. Our findings illuminate that PFKP participates in pathological cardiac hypertrophy partly by regulating protein synthesis through EIF2S2, which provides a new clue for the involvement of metabolic intermediates in signal transduction.

Bleomycin pollution and lung health: The therapeutic potential of peimine in bleomycin-induced pulmonary fibrosis by inhibiting glycolysis

The increasing use of anticancer drugs has led to the emergence of environmental contaminants such as bleomycin (BLM), which poses significant threats to both aquatic ecosystems and human health. Bleomycin, known for its DNA-damaging properties, is extensively used in oncology. Its resistance to biodegradation, along with the limitations of conventional wastewater treatment processes, facilitates environmental accumulation from various sources, highlighting the need for effective management and treatment strategies to mitigate ecological and health risks. This study investigates the link between BLM pollution and pulmonary fibrosis, a progressive lung disease characterized by tissue scarring and loss of function. We demonstrate that BLM induces pulmonary fibrosis in mice and enhances glycolysis and fibroblast activation. Our findings also indicate that peimine, a natural compound derived from Fritillaria, suppresses fibroblast activation and ameliorates pulmonary fibrosis by inhibiting glycolysis through the PI3K/Akt/PFKFB3 signaling pathway. Taken together, this study underscores the environmental and health risks associated with the accumulation of cytostatic drugs like BLM and highlights the therapeutic potential of natural compounds such as peimine. Our results contribute to the development of novel strategies for the prevention and treatment of pulmonary fibrosis and call for better management practices to mitigate the environmental impact of cytostatic drugs.

The PKM2/HIF-1α Axis is Involved in the Pathogenesis of Endometriosis via TGF-β1 under Endometrial Polyps

BACKGROUND

Endometriosis patients exhibit a cancer-like glycolytic phenotype. The pyruvate kinase M2 (PKM2)/hypoxia-inducible factor-1 alpha (HIF-1α) axis plays important roles in glycolysis-related diseases, but its role in patients with endometrial polyps (EPs) combined with endometriosis has not been validated.

METHODS

EP samples were collected from patients with and without endometriosis. PKM2, HIF-1α, and transforming growth factor-beta 1 (TGF-β1) levels were detected by immunohistochemistry (IHC), quantitative polymerase chain reaction, western blotting, and/or immunofluorescence. Primary endometrial stromal cells (ESCs) and non-endometriotic patient-derived ESCs (NESCs) were isolated from patients with EP with or without endometriosis. PKM2 loss-of-function assays in ESCs and gain-of-function assays in NESCs were performed to assess the function of PKM2. The effects of PKM2 and TGF-β1 on the promoter activity of HIF-1α were determined by dual-luciferase reporter assay.

RESULTS

PKM2 was overexpressed in ESCs compared to NESCs. Furthermore, PKM2 knockdown repressed viability, decreased migration and invasion, and restrained glycolysis of ESCs, accompanied by reduced HIF-1α levels and weakened promoter activity of HIF-1α. In addition, PKM2 overexpression had the opposite effect on these indicators in NESCs. Of note, an anti-TGF-β1 Ab reversed the PKM2-overexpression-mediated effects on cell viability, migration, and invasion, but not glycolysis or HIF-1α promoter activity, in NESCs. Additionally, PKM2, HIF-1α, and TGF-β1 levels were higher in EP samples with endometriosis than in EP samples without endometriosis, and there were positive correlations between PKM2, HIF-1α, and TGF-β1 IHC scores in all EP samples.

CONCLUSIONS

PKM2/HIF-1α-axis-dependent glycolysis participates in the pathogenesis of EP combined with endometriosis by mediating TGF-β1 signaling.

GLP-1R activation attenuates the progression of pulmonary fibrosis via disrupting NLRP3 inflammasome/PFKFB3-driven glycolysis interaction and histone lactylation

BACKGROUND

Pulmonary fibrosis is a serious interstitial lung disease with no viable treatment except for lung transplantation. Glucagon-like peptide-1 receptor (GLP-1R), commonly regarded as an antidiabetic target, exerts antifibrotic effects on various types of organ fibrosis. However, whether GLP-1R modulates the development and progression of pulmonary fibrosis remains unclear. In this study, we investigated the antifibrotic effect of GLP-1R using in vitro and in vivo models of pulmonary fibrosis.

METHODS

A silica-induced pulmonary fibrosis mouse model was established to evaluate the protective effects of activating GLP-1R with liraglutide in vivo. Primary cultured lung fibroblasts treated with TGF-β1 combined with IL-1β (TGF-β1 + IL-1β) were used to explore the specific effects of liraglutide, MCC950, and 3PO on fibroblast activation in vitro. Cell metabolism assay was performed to determine the glycolytic rate and mitochondrial respiration. RNA sequencing was utilized to analyse the underlying molecular mechanisms by which liraglutide affects fibroblast activation. ChIP‒qPCR was used to evaluate histone lactylation at the promoters of profibrotic genes in TGF-β1 + IL-1β- or exogenous lactate-stimulated lung fibroblasts.

RESULTS

Activating GLP-1R with liraglutide attenuated pulmonary inflammation and fibrosis in mice exposed to silica. Pharmacological inhibition of the NLRP3 inflammasome suppressed PFKFB3-driven glycolysis and vice versa, resulting in decreased lactate production in TGF-β1 + IL-1β-stimulated lung fibroblasts. Activating GLP-1R inhibited TGF-β1 + IL-1β-induced fibroblast activation by disrupting the interaction between the NLRP3 inflammasome and PFKFB3-driven glycolysis and subsequently prevented lactate-mediated histone lactylation to reduce pro-fibrotic gene expression. In addition, activating GLP-1R protected mitochondria against the TGF-β1 + IL-1β-induced increase in oxidative phosphorylation in fibroblasts. In exogenous lactate-treated lung fibroblasts, activating GLP-1R not only repressed NLRP3 inflammasome activation but also alleviated p300-mediated histone lactylation. Finally, GLP-1R activation blocked silica-treated macrophage-conditioned media-induced lung fibroblast activation.

CONCLUSIONS

The antifibrotic effects of GLP-1R activation on pulmonary fibrosis could be attributed to the inhibition of the interaction between NLRP3 inflammasome and PFKFB3-driven glycolysis, and histone lactylation in lung fibroblasts. Thus, GLP-1R is a specific therapeutic target for the treatment of pulmonary fibrosis.

Twist-related protein 1 promotes transforming growth factor β receptor 1 in keloid fibroblasts via regulating the stability of myocyte enhancer factor 2A

Background

Keloid scarring is caused by a fibroproliferative disorder due to abnormal activation of genes, the underlying mechanism of which is still unclear. The basic helix-loop-helix transcription factor Twist-related protein 1 (TWIST1) controls cell proliferation and differentiation in tissue development and disease processes. In this study, we aimed to clarify the essential role of TWIST1 in the pathogenesis of keloids.

Methods

Immunohistochemistry, cell counting kit-8 assays, western blotting, PCR, matrigel invasion assays and immunofluorescence assays were applied to demonstrate the effects and mechanisms of TWIST1 in fibroblasts derived from normal skin and keloids. Mass spectrometry, ubiquitination assays, chromatin immunoprecipitation and dual luciferase reporter assay were applied to explore the interaction of TWIST1 with downstream molecules.

Results

In the present study, we confirmed that TWIST1 was upregulated in keloid tissue of patients and in keloid-derived fibroblasts (KFBs). In vitro, TWIST1 inhibition prevented KFB proliferation, invasion and activation. We also discovered a link between TWIST1 and the transforming growth factor β (TGF-β) signaling related molecules TGF-β receptor 1 (TΒR1), SMAD family member 2 (Smad2) and Smad3, and the fibrosis markers α-smooth muscle actin, collagen type I and collagen type III in KFBs. Mechanistically, we uncovered a brand-new mechanism by which TWIST1 interacts with myocyte enhancer factor 2A (MEF2A) and suppresses its ubiquitination and degradation. Using chromatin immunoprecipitation and dual-luciferase reporter assay, TΒR1 was identified as a novel downstream target of MEF2A, which directly binds to its promoter. Overexpression of TWIST1 promoted the recruitment of MEF2A to the TΒR1 promoter and restored TΒR1 functional expression.

Conclusions

Our research highlights a significant function of TWIST1 in the development of keloid and its related fibroblasts, partially facilitated by elevated MEF2A-dependent TΒR1 expression. Blocking the expression of TWIST1 in KFBs could potentially pave a novel therapeutic avenue for keloid treatment.

Intermittent hyperglycaemia induces macrophage dysfunction by extracellular regulated protein kinase-dependent PKM2 translocation in periodontitis

Early fluctuations in blood glucose levels increased susceptibility to macrophage dysfunction. However, the underlying pathological mechanisms linking glucose variations and macrophage dysregulation remains elusive. In current study, we established an animal model of transient intermittent hyperglycaemia (TIH) to simulate early fluctuations in blood glucose levels. Our findings revealed that both TIH and diabetic group exhibited more severe periodontal lesions and increased secretion of pro-inflammatory cytokines compared to healthy controls. In immortalized bone marrow-derived macrophages (iBMDMs), phagocytosis and chemotaxis were impaired with transient and lasting hyperglycaemia, accompanied by enhanced glycolysis. We also found that TIH activated pyruvate kinase M2 (PKM2) through the phosphorylation of extracellular regulated protein kinase (ERK) in vivo, particularly at dimeric levels. In macrophage cultured with TIH, PKM2 translocated into the nucleus and involved in the regulating inflammatory genes, including TNF-α, IL-6 and IL-1β. PKM2 translocation and secretion of inflammatory cytokines were attenuated by PD98059, while PKM2 tetramer activator TEPP-46 prevented the formation of dimeric PKM2 in macrophages. Moreover, inhibition of glycolysis alleviated the TIH-induced pro-inflammatory cytokines. In conclusion, our manuscript provides a rationale for understanding how TIH modulates metabolic rewiring and dysfunction in macrophages via ERK-dependent PKM2 nuclear translocation.

Targeting reprogrammed metabolism as a therapeutic approach for respiratory diseases

Metabolic reprogramming underlies the etiology and pathophysiology of respiratory diseases such as asthma, idiopathic pulmonary fibrosis (IPF), and chronic obstructive pulmonary disease (COPD). The dysregulated cellular activities driving airway inflammation and remodelling in these diseases have reportedly been linked to aberrant shifts in energy-producing metabolic pathways: glycolysis and oxidative phosphorylation (OXPHOS). The rewiring of glycolysis and OXPHOS accompanying the therapeutic effects of many clinical compounds and natural products in asthma, IPF, and COPD, supports targeting metabolism as a therapeutic approach for respiratory diseases. Correspondingly, inhibiting glycolysis has largely attested effective against experimental asthma, IPF, and COPD. However, modulating OXPHOS and its supporting catabolic pathways like mitochondrial pyruvate catabolism, fatty acid β-oxidation (FAO), and glutaminolysis for these respiratory diseases remain inconclusive. An emerging repertoire of metabolic enzymes are also interconnected to these canonical metabolic pathways that similarly possess therapeutic potential for respiratory diseases. Taken together, this review highlights the urgent demand for future studies to ascertain the role of OXPHOS in different respiratory diseases, under different stimulatory conditions, and in different cell types. While this review provides strong experimental evidence in support of the inhibition of glycolysis for asthma, IPF, and COPD, further verification by clinical trials is definitely required.

TGFβ1-Induced Fibrotic Responses of Conjunctival Fibroblasts through the Wnt/β-Catenin/CRYAB Signaling Pathway

Conjunctival fibrosis is a common postoperative complication of glaucoma filtration surgery, resulting in uncontrolled intraocular pressure and surgery failure. Therefore, there is an urgent need to understand the molecular mechanisms underlying conjunctival fibrosis and to explore novel pharmacologic anti-fibrosis therapies for glaucoma filtration surgery. Herein, the 4-dimensional data-independent acquisition (4D-DIA) quantitative proteomic results, coupled with experimental data, revealed the activation of the Wnt/β-catenin pathway in transforming growth factor (TGF)-β1-induced human conjunctival fibroblasts (HConFs). Treatment with ICG-001, a Wnt/β-catenin inhibitor, effectively inhibited cell proliferation and migration in TGFβ1-treated HConFs. ICG-001 treatment alleviated the increased generation of extracellular matrix proteins induced by TGFβ1. In addition, ICG-001 reduced the expression level of α smooth muscle actin (α-SMA) and inhibited cell contractility in TGFβ1-treated HConFs. Proteomics data further suggested that αB-crystallin (CRYAB) was a downstream target of Wnt/β-catenin, which was up-regulated by TGFβ1 and down-regulated by ICG-001. Immunoblotting assay also indicated that ICG-001 reduced the expressions of ubiquitin and β-catenin in TGFβ1-treated HConFs, implying that CRYAB stabilized β-catenin by inhibiting its ubiquitination degradation. Exogenous CRYAB promoted cell viability, increased extracellular matrix protein levels, and up-regulated α-SMA expression of HConFs under TGFβ1 stimulation. CRYAB rescued TGFβ1-induced fibrotic responses that were suppressed by ICG-001. In conclusion, this study elucidates the regulatory mechanism of the Wnt/β-catenin/CRYAB pathway in conjunctival fibrosis, offering promising therapeutic targets for mitigating bleb scarring after glaucoma filtration surgery.

PKM2/Hif-1α signal suppression involved in therapeutics of pulmonary fibrosis with microcystin-RR but not with pirfenidone

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.

Compound 3K attenuates isoproterenol-induced cardiac hypertrophy by inhibiting pyruvate kinase M2 (PKM2) pathway

AIM

Chronic sympathetic stimulation has been identified as a primary factor in the pathogenesis of cardiac hypertrophy (CH). However, there is no appropriate treatment available for the management of CH. Recently, it has been revealed that pyruvate kinase M2 (PKM2) plays a significant role in cardiac remodeling, fibrosis, and hypertrophy. However, the therapeutic potential of selective PKM2 inhibitor has not yet been explored in cardiac hypertrophy. Thus, in the current study, we have studied the cardioprotective potential of Compound 3K, a selective PKM2 inhibitor in isoproterenol-induced CH model.

METHODS

To induce cardiac hypertrophy, male Wistar rats were subcutaneously administered isoproterenol (ISO, 5 mg/kg/day) for 14 days. Compound 3K at dosages of 2 and 4 mg/kg orally was administered to ISO-treated rats for 14 days to explore its effects on various parameters like ECG, ventricular functions, hypertrophic markers, histology, inflammation, and protein expression were performed.

RESULTS

Fourteen days administration of ISO resulted in the induction of CH, which was evidenced by alterations in ECG, ventricular dysfunctions, increase in hypertrophy markers, and fibrosis. The immunoblotting of hypertrophy heart revealed the significant rise in PKM2 and reduction in PKM1 protein expression. Treatment with Compound 3K led to downregulation of PKM2 and upregulation of PKM1 protein expression. Compound 3K showed cardioprotective effects by improving ECG, cardiac functions, hypertrophy markers, inflammation, and fibrosis. Further, it also reduced cardiac expression of PKM2-associated splicing protein, HIF-1α, and caspase-3.

CONCLUSION

Our findings suggest that Compound 3K has a potential cardioprotective effect via PKM2 inhibition in isoproterenol-induced CH.

Injectable, degradable, and mechanically adaptive hydrogel induced by L-serine and allyl-functionalized chitosan with platelet-rich plasma for treating intrauterine adhesions

The integration of barrier materials with pharmacological therapy is a promising strategy to treat intrauterine adhesions (IUAs). However, most of these materials are surgically implanted in a fixed shape and incongruence with the natural mechanical properties of the uterus, causing poor adaptability and significant discomfort to the patients. Herein, an injectable, biodegradable, and mechanically adaptive hydrogel loaded with platelet-rich plasma (PRP) is created by L‑serine and allyl functionalized chitosan (ACS) to achieve efficient, comfortable, and minimally invasive treatment of IUAs. L‑serine induces fast gelation and mechanical reinforcement of the hydrogel, while ACS introduces, imparting a good injectability and complaint yet strong feature to the hydrogel. This design enables the hydrogel to adapt to the complex geometry and match the mechanical properties of the uterine. Moreover, the hydrogel exhibits proper degradability, sustained growth factors (GFs) of PRP release ability, and good biocompatibility. Consequently, the hydrogel shows promising therapeutic efficacy by reducing collagen fiber deposition and facilitating endometrium cell proliferation, thereby restoring the fertility function of the uterus in an IUAs model of rats. Accordingly, the combination of L‑serine and ACS-induced hydrogel with such advantages holds great potential for treating IUAs. STATEMENT OF SIGNIFICANCE: This research introduces a breakthrough in the treatment of intrauterine adhesions (IUAs) with an injectable, biodegradable and mechanically adaptive hydrogel using L‑serine and allyl functionalized chitosan (ACS). Unlike traditional surgical treatments, this hydrogel uniquely conforms to the uterus's geometry and mechanical properties, offering a minimally invasive, comfortable, and more effective solution. The hydrogel is designed to release growth factors from platelet-rich plasma (PRP) sustainably, promoting tissue regeneration by enhancing collagen fiber deposition and endometrium cell proliferation. Demonstrated efficacy in a rat model of IUAs indicates its great potential to significantly improve fertility restoration treatments. This advancement represents a significant leap in reproductive medicine, promising to transform IUAs treatment with its innovative approach to achieving efficient, comfortable, and minimally invasive therapy.

Deletion of GPR81 activates CREB/Smad7 pathway and alleviates liver fibrosis in mice

BACKGROUND

Enhanced glycolysis is a crucial metabolic event that drives the development of liver fibrosis, but the molecular mechanisms have not been fully understood. Lactate is the endproduct of glycolysis, which has recently been identified as a bioactive metabolite binding to G-protein-coupled receptor 81 (GPR81). We then questioned whether GPR81 is implicated in the development of liver fibrosis.

METHODS

The level of GPR81 was determined in mice with carbon tetrachloride (CCl4)-induced liver fibrosis and in transforming growth factor beta 1 (TGF-β1)-activated hepatic stellate cells (HSCs) LX-2. To investigate the significance of GPR81 in liver fibrosis, wild-type (WT) and GPR81 knockout (KO) mice were exposed to CCl4, and then the degree of liver fibrosis was determined. In addition, the GPR81 agonist 3,5-dihydroxybenzoic acid (DHBA) was supplemented in CCl4-challenged mice and TGF-β1-activated LX-2 cells to further investigate the pathological roles of GPR81 on HSCs activation.

RESULTS

CCl4 exposure or TGF-β1 stimulation significantly upregulated the expression of GPR81, while deletion of GPR81 alleviated CCl4-induced elevation of aminotransferase, production of pro-inflammatory cytokines, and deposition of collagen. Consistently, the production of TGF-β1, the expression of alpha-smooth muscle actin (α-SMA) and collagen I (COL1A1), as well as the elevation of hydroxyproline were suppressed in GPR81 deficient mice. Supplementation with DHBA enhanced CCl4-induced liver fibrogenesis in WT mice but not in GPR81 KO mice. DHBA also promoted TGF-β1-induced LX-2 activation. Mechanistically, GPR81 suppressed cAMP/CREB and then inhibited the expression of Smad7, a negative regulator of Smad3, which resulted in increased phosphorylation of Smad3 and enhanced activation of HSCs.

CONCLUSION

GPR81 might be a detrimental factor that promotes the development of liver fibrosis by regulating CREB/Smad7 pathway.

Supramolecular Nanofibers Ameliorate Bleomycin-Induced Pulmonary Fibrosis by Restoring Autophagy

Idiopathic pulmonary fibrosis (IPF) is a progressive and ultimately fatal interstitial lung disease, with limited therapeutic options available. Impaired autophagy resulting from aberrant TRB3/p62 protein-protein interactions (PPIs) contributes to the progression of IPF. Restoration of autophagy by modulating the TRB3/p62 PPIs has rarely been reported for the treatment of IPF. Herein, peptide nanofibers are developed that specifically bind to TRB3 protein and explored their potential as a therapeutic approach for IPF. By conjugating with the self-assembling fragment (Ac-GFFY), a TRB3-binding peptide motif A2 allows for the formation of nanofibers with a stable α-helix secondary structure. The resulting peptide (Ac-GFFY-A2) nanofibers exhibit specific high-affinity binding to TRB3 protein in saline buffer and better capacity of cellular uptake to A2 peptide. Furthermore, the TRB3-targeting peptide nanofibers efficiently interfere with the aberrant TRB3/p62 PPIs in activated fibroblasts and fibrotic lung tissue of mice, thereby restoring autophagy dysfunction. The TRB3-targeting peptide nanofibers inhibit myofibroblast differentiation, collagen production, and fibroblast migration in vitro is demonstrated, as well as bleomycin-induced pulmonary fibrosis in vivo. This study provides a supramolecular method to modulate PPIs and highlights a promising strategy for treating IPF diseases by restoring autophagy.

Exosomal miR-17-5p derived from epithelial cells is involved in aberrant epithelium-fibroblast crosstalk and induces the development of oral submucosal fibrosis

Oral submucous fibrosis (OSF) is a chronic and inflammatory mucosal disease caused by betel quid chewing, which belongs to oral potentially malignant disorders. Abnormal fibroblast differentiation leading to disordered collagen metabolism is the core process underlying OSF development. The epithelium, which is the first line of defense against the external environment, can convert external signals into pathological signals and participate in the remodeling of the fibrotic microenvironment. However, the specific mechanisms by which the epithelium drives fibroblast differentiation remain unclear. In this study, we found that Arecoline-exposed epithelium communicated with the fibrotic microenvironment by secreting exosomes. MiR-17-5p was encapsulated in epithelial cell-derived exosomes and absorbed by fibroblasts, where it promoted cell secretion, contraction, migration and fibrogenic marker (α-SMA and collagen type I) expression. The underlying molecular mechanism involved miR-17-5p targeting Smad7 and suppressing the degradation of TGF-β receptor 1 (TGFBR1) through the E3 ubiquitination ligase WWP1, thus facilitating downstream TGF-β pathway signaling. Treatment of fibroblasts with an inhibitor of miR-17-5p reversed the contraction and migration phenotypes induced by epithelial-derived exosomes. Exosomal miR-17-5p was confirmed to function as a key regulator of the phenotypic transformation of fibroblasts. In conclusion, we demonstrated that Arecoline triggers aberrant epithelium-fibroblast crosstalk and identified that epithelial cell-derived miR-17-5p mediates fibroblast differentiation through the classical TGF-β fibrotic pathway, which provided a new perspective and strategy for the diagnosis and treatment of OSF.

Targeting pyruvate kinase M2 for the treatment of kidney disease

Pyruvate kinase M2 (PKM2), a rate limiting enzyme in glycolysis, is a cellular regulator that has received extensive attention and regards as a metabolic regulator of cellular metabolism and energy. Kidney is a highly metabolically active organ, and glycolysis is the important energy resource for kidney. The accumulated evidences indicates that the enzymatic activity of PKM2 is disturbed in kidney disease progression and treatment, especially diabetic kidney disease and acute kidney injury. Modulating PKM2 post-translational modification determines its enzymatic activity and nuclear translocation that serves as an important interventional approach to regulate PKM2. Emerging evidences show that PKM2 and its post-translational modification participate in kidney disease progression and treatment through modulating metabolism regulation, podocyte injury, fibroblast activation and proliferation, macrophage polarization, and T cell regulation. Interestingly, PKM2 activators (TEPP-46, DASA-58, mitapivat, and TP-1454) and PKM2 inhibitors (shikonin, alkannin, compound 3k and compound 3h) have exhibited potential therapeutic property in kidney disease, which indicates the pleiotropic effects of PKM2 in kidney. In the future, the deep investigation of PKM2 pleiotropic effects in kidney is urgently needed to determine the therapeutic effect of PKM2 activator/inhibitor to benefit patients. The information in this review highlights that PKM2 functions as a potential biomarker and therapeutic target for kidney diseases.

Pulmonary redox imbalance drives early fibroproliferative response in moderate/severe coronavirus disease-19 acute respiratory distress syndrome and impacts long-term lung abnormalities

BACKGROUND

COVID-19-associated pulmonary fibrosis remains frequent. This study aimed to investigate pulmonary redox balance in COVID-19 ARDS patients and possible relationship with pulmonary fibrosis and long-term lung abnormalities.

METHODS

Baseline data, chest CT fibrosis scores, N-terminal peptide of alveolar collagen III (NT-PCP-III), transforming growth factor (TGF)-β1, superoxide dismutase (SOD), reduced glutathione (GSH), oxidized glutathione (GSSG) and malondialdehyde (MDA) in bronchoalveolar lavage fluid (BALF) were first collected and compared between SARS-CoV-2 RNA positive patients with moderate to severe ARDS (n = 65, COVID-19 ARDS) and SARS-CoV-2 RNA negative non-ARDS patients requiring mechanical ventilation (n = 63, non-ARDS). Then, correlations between fibroproliferative (NT-PCP-III and TGF-β1) and redox markers were analyzed within COVID-19 ARDS group, and comparisons between survivor and non-survivor subgroups were performed. Finally, follow-up of COVID-19 ARDS survivors was performed to analyze the relationship between pulmonary abnormalities, fibroproliferative and redox markers 3 months after discharge.

RESULTS

Compared with non-ARDS group, COVID-19 ARDS group had significantly elevated chest CT fibrosis scores (p < 0.001) and NT-PCP-III (p < 0.001), TGF-β1 (p < 0.001), GSSG (p < 0.001), and MDA (p < 0.001) concentrations on admission, while decreased SOD (p < 0.001) and GSH (p < 0.001) levels were observed in BALF. Both NT-PCP-III and TGF-β1 in BALF from COVID-19 ARDS group were directly correlated with GSSG (p < 0.001) and MDA (p < 0.001) and were inversely correlated with SOD (p < 0.001) and GSH (p < 0.001). Within COVID-19 ARDS group, non-survivors (n = 28) showed significant pulmonary fibroproliferation (p < 0.001) with more severe redox imbalance (p < 0.001) than survivors (n = 37). Furthermore, according to data from COVID-19 ARDS survivor follow-up (n = 37), radiographic residual pulmonary fibrosis and lung function impairment improved 3 months after discharge compared with discharge (p < 0.001) and were associated with early pulmonary fibroproliferation and redox imbalance (p < 0.01).

CONCLUSIONS

Pulmonary redox imbalance occurring early in COVID-19 ARDS patients drives fibroproliferative response and increases the risk of death. Long-term lung abnormalities post-COVID-19 are associated with early pulmonary fibroproliferation and redox imbalance.

Leech extract alleviates idiopathic pulmonary fibrosis by TGF-β1/Smad3 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Leech, as a traditional Chinese medicine for the treatment of blood circulation and blood stasis, was also widely used to cure pulmonary fibrosis in China. In clinical practice, some traditional Chinese medicine preparation such as Shui Zhi Xuan Bi Hua Xian Tang and Shui Zhi Tong Luo Capsule composed of leech, could improve the clinical symptoms and pulmonary function in patients with idiopathic pulmonary fibrosis (IPF). However, the material basis of the leech in the treatment of IPF were not yet clear.

AIM OF THE STUDY

Screen out the components of leech that have the anti-pulmonary fibrosis effects, and further explore the therapeutic mechanism of the active components.

MATERIALS AND METHODS

In this study, the different molecular weight components of leech extract samples were prepared using the semi-permeable membranes with different pore sizes. The therapeutic effects of the leech extract groups with molecular weight greater than 10 KDa (>10 KDa group), between 3 KDa and 10 KDa (3-10 KDa group), and less than 3 KDa (<3 KDa group) on pulmonary fibrosis were firstly investigated by cell proliferation and cytotoxicity assay (MTT), cell wound healing assay, immunofluorescence staining (IF) and Western blot (WB) assay through the TGF-β1-induced fibroblast cell model. Then bleomycin-induced pulmonary fibrosis (BML-induced PF) mouse model was constructed to investigate the pharmacological activities of the active component group of leech extract in vivo. Pathological changes of the mouse lung were observed by hematoxylin-eosin staining (H&E) and Masson's trichrome staining (Masson). The hydroxyproline (HYP) content of lung tissues was quantified by HYP detection kit. The levels of extracellular matrix-related fibronectin (FN) and collagen type Ⅰ (Collagen Ⅰ), pyruvate kinase M2 (PKM2) monomer and Smad7 protein were determined via WB method. PKM2 and Smad7 protein were further characterized by IF assays.

RESULTS

Using TGF-β1-induced HFL1 cell line as a PF cell model, the in vitro results demonstrated that the >10 KDa group could significantly inhibited the cell proliferation and migration, downregulated the expression level of cytoskeletal protein vimentin and α-smooth muscle actin (α-SMA), and reduced the deposition of FN and Collagen Ⅰ. In the BML-induced PF mouse model, the >10 KDa group significantly reduced the content of HYP, downregulated the expression levels of FN and Collagen Ⅰ in lung tissues, and delayed the pathological changes of lung tissue structure. The results of WB and IF assays further indicated that the >10 KDa group could up-regulate the expression level of PKM2 monomer and Smad7 protein in the cellular level, thereby delaying the progression of pulmonary fibrosis.

CONCLUSIONS

Our study revealed that the >10 KDa group was the main material basis of the leech extract that inhibited pulmonary fibrosis through TGF-β1/Smad3 signaling pathway.

[Research advances on the role of aerobic glycolysis in skin fibrosis diseases]

Skin fibrosis diseases mainly include hypertrophic scar, keloid, and systemic sclerosis, etc. The main pathological features are excessive activation of fibroblasts and abnormal deposition of extracellular matrix. In recent years, studies have shown that aerobic glycolysis is closely related to the occurrence and development of skin fibrosis diseases. Drugs targeting aerobic glycolysis has provided new ideas for skin anti-fibrosis treatment. This article reviews the role of enzymes and products related to aerobic glycolysis in the occurrence and development of skin fibrosis diseases and the drugs targeting aerobic glycolysis for the treatment of skin fibrosis diseases.

Cardioprotective potential of compound 3K, a selective PKM2 inhibitor in isoproterenol-induced acute myocardial infarction: A mechanistic study

Myocardial infarction (MI) or heart attack arises from acute or chronic prolonged ischemic conditions in the myocardium. Although several risk factors are associated with MI pathophysiology, one of the risk factors is an imbalance in the oxygen supply. The current available MI therapies are still inadequate due to the complexity of MI pathophysiology. Pyruvate kinase M2 (PKM2) has been implicated in numerous CVDs pathologies. However, the effect of specific pharmacological intervention targeting PKM2 has not been studied in MI. Therefore, in this study, we explored the effect of compound 3K, a PKM2-specific inhibitor, in isoproterenol-induced acute MI model. In this study, in order to induce MI in rats, isoproterenol (ISO) was administered at a dose of 100 mg/kg over two days at an interval of 24 h. Specific PKM2 inhibitor, compound 3K (2 and 4 mg/kg), was administered in MI rats to investigate its cardioprotective potential. After the last administration of compound 3K, ECG and hemodynamic parameters were recorded using a PV-loop system. Cardiac histology, western blotting, and plasmatic cardiac damage markers were evaluated to elucidate the underlying mechanisms. Treatment of compound 3K significantly reduced ISO-induced alterations in ECG, ventricular functions, cardiac damage, infarct size, and cardiac fibrosis. Compound 3K treatment produced significant increase in PKM1 expression and decrease in PKM2 expression. In addition, HIF-1α, caspase-3, c-Myc, and PTBP1 expression were also reduced after compound 3K treatment. This study demonstrates the cardioprotective potential of compound 3K in MI, and its mechanisms of cardioprotective action.

Search progress of pyruvate kinase M2 (PKM2) in organ fibrosis

Fibrosis is characterized by abnormal deposition of the extracellular matrix (ECM), leading to organ structural remodeling and loss of function. The principal cellular effector in fibrosis is activated myofibroblasts, which serve as the main source of matrix proteins. Metabolic reprogramming, transitioning from mitochondrial oxidative phosphorylation to aerobic glycolysis, is widely observed in rapidly dividing cells such as tumor cells and activated myofibroblasts and is increasingly recognized as a fundamental pathogenic basis in organ fibrosis. Targeting metabolism represents a promising strategy to mitigate fibrosis. PKM2, a key enzyme in glycolysis, plays a pivotal role in metabolic reprogramming through allosteric regulation, impacting both metabolic and non-metabolic pathways. Therefore, metabolic reprogramming induced by PKM2 activation is involved in the occurrence and development of fibrosis in various organs. A comprehensive understanding of the role of PKM2 in fibrotic diseases is crucial for seeking new anti-fibrotic therapeutic targets. In this context, we summarize PKM2's role in glycolysis, mediating the intricate mechanisms underlying fibrosis in multiple organs, and discuss the potential value of PKM2 inhibitors and allosteric activators in future clinical treatments, aiming to identify novel therapeutic targets for proliferative fibrotic diseases.

Tetrahedral DNA loaded siCCR2 restrains M1 macrophage polarization to ameliorate pulmonary fibrosis in chemoradiation-induced murine model

Idiopathic pulmonary fibrosis (IPF) is a chronic lethal disease in the absence of demonstrated efficacy for preventing progression. Although macrophage-mediated alveolitis is determined to participate in myofibrotic transition during disease development, the paradigm of continuous macrophage polarization is still under-explored due to lack of proper animal models. Here, by integrating 2.5 U/kg intratracheal Bleomycin administration and 10 Gy thorax irradiation at day 7, we generated a murine model with continuous alveolitis-mediated fibrosis, which mimics most of the clinical features of our involved IPF patients. In combination with data from scRNA-seq of patients and a murine IPF model, a decisive role of CCL2/CCR2 axis in driving M1 macrophage polarization was revealed, and M1 macrophage was further confirmed to boost alveolitis in leading myofibroblast activation. Multiple sticky-end tetrahedral framework nucleic acids conjunct with quadruple ccr2-siRNA (FNA-siCCR2) was synthesized in targeting M1 macrophages. FNA-siCCR2 successfully blocked macrophage accumulation in pulmonary parenchyma of the IPF murine model, thus preventing myofibroblast activation and leading to the disease remitting. Overall, our studies lay the groundwork to develop a novel IPF murine model, reveal M1 macrophages as potential therapeutic targets, and establish new treatment strategy by using FNA-siCCR2, which are highly relevant to clinical scenarios and translational research in the field of IPF.

Granzyme B PET imaging inflammation and remodeling in myocardial infarction

PURPOSE

This study aimed to evaluate whether granzyme B (GzmB)-targeted positron emission tomography (PET) imaging agent (68 Ga-grazytracer) can characterize cardiac inflammation and remodeling in myocardial infarction (MI).

METHODS

Rats with MI were subjected to GzmB-targeted PET/CT on post-operative days 1, 3, 6, 14, and 28. Autoradiography, Masson staining, immunohistochemistry, and ELISA were performed to verify the inflammatory response and remodeling after MI in vitro. Rats were treated with GzmB inhibitor Z-IETD-FMK to improve cardiac remodeling. Cardiac function tests were performed by echocardiography at 6 weeks after MI.

RESULTS

The highest uptake of 68 Ga-grazytracer was observed on day 3 after MI compared with the values obtained on the other days (0.294 ± 0.03% ID/g at 3 days vs. 0.122 ± 0.01% ID/g in the sham group, P < 0.001). Immunohistochemistry showed significantly high expression of GzmB and CD8, in line with the PET/CT imaging results. Autoradiography revealed 68 Ga-grazytracer accumulation in the infarcted myocardium. The 68 Ga-grazytracer uptake of treated rats was significantly reduced compared with that in the MI groups (0.184 ± 0.03%ID/g vs. 0.286 ± 0.03%ID/g; P < 0.001). Echocardiography showed that the left ventricular ejection fraction was lower in the MI groups than in the ischemia reperfusion group. GzmB inhibitor treatment was shown to be effective in improving cardiac function without significantly shortening infarct size.

CONCLUSIONS

This study demonstrated the potential of 68 Ga-grazytracer imaging to delineate adverse inflammatory responses and pathological cardiac remodeling, which can help predict heart function. PET/CT imaging-guided therapy may reduce myocardial injury and improve heart function in MI.

Targeted inhibition of transforming growth factor-β type I receptor by AZ12601011 improves paraquat poisoning-induced multiple organ fibrosis

Paraquat (PQ) causes fatal poisoning that leads to systemic multiple organ fibrosis, and transforming growth factor (TGF)-β1 plays a critical role in this process. In this study, we aimed to investigate the effects of AZ12601011 (a small molecular inhibitor of TGFβRI) on PQ-induced multiple organ fibrosis. We established a mouse model of PQ in vivo and used PQ-treated lung epithelial cell (A549) and renal tubular epithelial cells (TECs) in vitro. Haematoxylin-eosin and Masson staining revealed that AZ12601011 ameliorated pulmonary, hepatic, and renal fibrosis, consistent with the decrease in the levels of fibrotic indicators, alpha-smooth muscle actin (α-SMA) and collagen-1, in the lungs and kidneys of PQ-treated mice. In vitro data showed that AZ12601011 suppressed the induction of α-SMA and collagen-1 in PQ-treated A549 cells and TECs. In addition, AZ12601011 inhibited the release of inflammatory factors, interleukin (IL)-1β, IL-6, and tumour necrosis factor-α. Mechanistically, TGF-β and TGFβRI levels were significantly upregulated in the lungs and kidneys of PQ-treated mice. Cellular thermal shift assay and western blotting revealed that AZ12601011 directly bound with TGFβRI and blocked the activation of Smad3 downstream. In conclusion, our findings revealed that AZ12601011 attenuated PQ-induced multiple organ fibrosis by blocking the TGF-β/Smad3 signalling pathway, suggesting its potential for PQ poisoning treatment.

Pyruvate kinase M2 regulates kidney fibrosis through pericyte glycolysis during the progression from acute kidney injury to chronic kidney disease

We aimed to investigate the role of renal pericyte pyruvate kinase M2 (PKM2) in the progression of acute kidney injury (AKI) to chronic kidney disease (CKD). The role of PKM2 in renal pericyte-myofibroblast transdifferentiation was investigated in an AKI-CKD mouse model. Platelet growth factor receptor beta (PDGFRβ)-iCreERT2; tdTomato mice were used for renal pericyte tracing. Western blotting and immunofluorescence staining were used to examine protein expression. An 5-ethynyl-2'-deoxyuridine assay was used to measure renal pericyte proliferation. A scratch cell migration assay was used to analyse cell migration. Seahorse experiments were used to examine glycolytic rates. Enzyme-linked immunoassay was used to measure pyruvate kinase enzymatic activity and lactate concentrations. The PKM2 nuclear translocation inhibitors Shikonin and TEPP-46 were used to alter pericyte transdifferentiation. In AKI-CKD, renal pericytes proliferated and transdifferentiated into myofibroblasts and PKM2 is highly expressed in renal pericytes. Shikonin and TEPP-46 inhibited pericyte proliferation, migration, and pericyte-myofibroblast transdifferentiation by reducing nuclear PKM2 entry. In the nucleus, PKM2 promoted downstream lactate dehydrogenase A (LDHA) and glucose transporter 1 (GLUT1) transcription, which are critical for glycolysis. Therefore, PKM2 regulates pericyte glycolytic and lactate production, which regulates renal pericyte-myofibroblast transdifferentiation. PKM2-regulated renal pericyte-myofibroblast transdifferentiation by regulating downstream LDHA and GLUT1 transcription and lactate production. Reducing nuclear PKM2 import can reduce renal pericytes-myofibroblasts transdifferentiation, providing new ideas for AKI-CKD treatment.

Glycolysis Reprogramming in Idiopathic Pulmonary Fibrosis: Unveiling the Mystery of Lactate in the Lung

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive lung disease characterized by excessive deposition of fibrotic connective tissue in the lungs. Emerging evidence suggests that metabolic alterations, particularly glycolysis reprogramming, play a crucial role in the pathogenesis of IPF. Lactate, once considered a metabolic waste product, is now recognized as a signaling molecule involved in various cellular processes. In the context of IPF, lactate has been shown to promote fibroblast activation, myofibroblast differentiation, and extracellular matrix remodeling. Furthermore, lactate can modulate immune responses and contribute to the pro-inflammatory microenvironment observed in IPF. In addition, lactate has been implicated in the crosstalk between different cell types involved in IPF; it can influence cell-cell communication, cytokine production, and the activation of profibrotic signaling pathways. This review aims to summarize the current research progress on the role of glycolytic reprogramming and lactate in IPF and its potential implications to clarify the role of lactate in IPF and to provide a reference and direction for future research. In conclusion, elucidating the intricate interplay between lactate metabolism and fibrotic processes may lead to the development of innovative therapeutic strategies for IPF.

Inhibition of PFKP in renal tubular epithelial cell restrains TGF-β induced glycolysis and renal fibrosis

Metabolic reprogramming to glycolysis is closely associated with the development of chronic kidney disease (CKD). Although it has been reported that phosphofructokinase 1 (PFK) is a rate-limiting enzyme in glycolysis, the role of the platelet isoform of PFK (PFKP) in kidney fibrosis initiation and progression is as yet poorly understood. Here, we investigated whether PFKP could mediate the progression of kidney interstitial fibrosis by regulating glycolysis in proximal tubular epithelial cells (PTECs). We induced PFKP overexpression or knockdown in renal tubules via an adeno-associated virus (AAV) vector in the kidneys of mice following unilateral ureteral occlusion. Our results show that the dilated tubules, the area of interstitial fibrosis, and renal glycolysis were promoted by proximal tubule-specific overexpression of PFKP, and repressed by knockdown of PFKP. Furthermore, knockdown of PFKP expression restrained, while PFKP overexpression promoted TGF-β1-induced glycolysis in the human PTECs line. Mechanistically, Chip-qPCR revealed that TGF-β1 recruited the small mothers against decapentaplegic (SMAD) family member 3-SP1 complex to the PFKP promoter to enhance its expression. Treatment of mice with isorhamnetin notably ameliorated PTEC-elevated glycolysis and kidney fibrosis. Hence, our results suggest that PFKP mediates the progression of kidney interstitial fibrosis by regulating glycolysis in PTECs.

M-type pyruvate kinase 2 (PKM2) tetramerization alleviates the progression of right ventricle failure by regulating oxidative stress and mitochondrial dynamics

BACKGROUND

Right ventricle failure (RVF) is a progressive heart disease that has yet to be fully understood at the molecular level. Elevated M-type pyruvate kinase 2 (PKM2) tetramerization alleviates heart failure, but detailed molecular mechanisms remain unclear.

OBJECTIVE

We observed changes in PKM2 tetramerization levels during the progression of right heart failure and in vitro cardiomyocyte hypertrophy and explored the causal relationship between altered PKM2 tetramerization and the imbalance of redox homeostasis in cardiomyocytes, as well as its underlying mechanisms. Ultimately, our goal was to propose rational intervention strategies for the treatment of RVF.

METHOD

We established RVF in Sprague Dawley (SD) rats by intraperitoneal injection of monocrotaline (MCT). The pulmonary artery pressure and right heart function of rats were assessed using transthoracic echocardiography combined with right heart catheterization. TEPP-46 was used both in vivo and in vitro to promote PKM2 tetramerization.

RESULTS

We observed that oxidative stress and mitochondrial disorganization were associated with increased apoptosis in the right ventricular tissue of RVF rats. Quantitative proteomics revealed that PKM2 was upregulated during RVF and negatively correlated with the cardiac function. Facilitating PKM2 tetramerization promoted mitochondrial network formation and alleviated oxidative stress and apoptosis during cardiomyocyte hypertrophy. Moreover, enhancing PKM2 tetramer formation improved cardiac mitochondrial morphology, mitigated oxidative stress and alleviated heart failure.

CONCLUSION

Disruption of PKM2 tetramerization contributed to RVF by inducing mitochondrial fragmentation, accumulating ROS, and finally promoted the progression of cardiomyocyte apoptosis. Facilitating PKM2 tetramerization holds potential as a promising therapeutic approach for RVF.

Imrecoxib attenuates bleomycin-induced pulmonary fibrosis in mice

Idiopathic pulmonary fibrosis (IPF) is an incurable chronic progressive disease with a low survival rate and ineffective therapeutic options. We examined the effects of imrecoxib, a nonsteroidal anti-inflammatory drug, on experimental pulmonary fibrosis. The mouse IPF model was established by intratracheal instillation of bleomycin. From Day 0 to Day 13, the mice were orally administered imrecoxib (100 mg/kg) and pirfenidone (200 mg/kg) daily, and from Day 7 to Day 13, the mice were orally administered pirfenidone and imrecoxib daily. The tissues were dissected on the 14th day. Mouse body weight was measured, and histopathological examination and hydroxyproline content analysis confirmed that the administration of imrecoxib exerted a similar effect to pirfenidone. Compared with bleomycin-induced mice, imrecoxib-treated mice showed significantly reduced inflammatory factor expression (IL-1 and TNF-α) and inflammatory cell numbers (macrophages, lymphocytes, and neutrophils) in BALF (bronchoalveolar lavage fluid). Our experiment tested the ability of imrecoxib to inhibit the signal pathway involved in gene expression induced by TGF-β1 in the NIH-3T3 cell line in vitro. Western blotting showed that imrecoxib (20 μM and 40 μM) inhibited the expression of fibronectin, type I collagen and CTGF. In addition, imrecoxib reduced the levels of p-ERK1/2. The changes in the expression of related proteins in mouse lung tissue were similar to those in cells. In summary, our findings suggested that the administration of imrecoxib prevented and treated murine IPF by inhibiting inflammation and the TGF-β1-ERK1/2 signaling pathway.

Identification and validation of targets of swertiamarin on idiopathic pulmonary fibrosis through bioinformatics and molecular docking-based approach

BACKGROUND

Swertiamarin is the main hepatoprotective component of Swertiapatens and has anti-inflammatory and antioxidation effects. Our previous study showed that it was a potent inhibitor of idiopathic pulmonary fibrosis (IPF) and can regulate the expressions of α-smooth muscle actin (α-SMA) and epithelial cadherin (E-cadherin), two markers of the TGF-β/Smad (transforming growth factor beta/suppressor of mothers against decapentaplegic family) signaling pathway. But its targets still need to be investigated. The main purpose of this study is to identify the targets of swertiamarin.

METHODS

GEO2R was used to analyze the differentially expressed genes (DEGs) of GSE10667, GSE110147, and GSE71351 datasets from the Gene Expression Omnibus (GEO) database. The DEGs were then enriched with Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis for their biological functions and annotated terms. The protein-protein interaction (PPI) network was constructed to identify hub genes. The identified hub genes were predicted for their bindings to swertiamarin by molecular docking (MD) and validated by experiments.

RESULTS

76 upregulated and 27 downregulated DEGs were screened out. The DEGs were enriched in the biological function of cellular component (CC) and 7 cancer-related signaling pathways. Three hub genes, i.e., LOX (lysyl oxidase), COL5A2 (collagen type V alpha 2 chain), and CTGF (connective tissue growth factor) were selected, virtually tested for the interactions with swertiamarin by MD, and validated by in vitro experiments.

CONCLUSION

LOX, COL5A2, and CTGF were identified as the targets of swertiamarin on IPF.

Lactate acidosis and simultaneous recruitment of TGF-β leads to alter plasticity of hypoxic cancer cells in tumor microenvironment

Lactate acidosis is often observed in the tumor microenvironment (TME) of solid tumors. This is because glucose breaks down quickly via glycolysis, causing lactate acidity. Lactate is harmful to healthy cells, but is a major oncometabolite for solid cancer cells that do not receive sufficient oxygen. As an oncometabolite, it helps tumor cells perform different functions, which helps solid hypoxic tumor cells spread to other parts of the body. Studies have shown that the acidic TME contains VEGF, Matrix metalloproteinases (MMPs), cathepsins, and transforming growth factor-β (TGF-β), all of which help spread in direct and indirect ways. Although each cytokine is important in its own manner in the TME, TGF-β has received much attention for its role in metastatic transformation. Several studies have shown that lactate acidosis can cause TGF-β expression in solid hypoxic cancers. TGF-β has also been reported to increase the production of fatty acids, making cells more resistant to treatment. TGF-β has also been shown to control the expression of VEGF and MMPs, which helps solid hypoxic tumors become more aggressive by helping them spread and create new blood vessels through an unknown process. The role of TGF-β under physiological conditions has been described previously. In this study, we examined the role of TGF-β, which is induced by lactate acidosis, in the spread of solid hypoxic cancer cells. We also found that TGF-β and lactate work together to boost fatty acid production, which helps angiogenesis and invasiveness.

N-Acetylglucosamine mitigates lung injury and pulmonary fibrosis induced by bleomycin

Lung injury and pulmonary fibrosis contribute to morbidity and mortality, and, in particular, are characterized as leading cause on confirmed COVID-19 death. To date, efficient therapeutic approach for such lung diseases is lacking. N-Acetylglucosamine (NAG), an acetylated derivative of glucosamine, has been proposed as a potential protector of lung function in several types of lung diseases. The mechanism by which NAG protects against lung injury, however, remains unclear. Here, we show that NAG treatment improves pulmonary function in bleomycin (BLM)-induced lung injury model measured by flexiVent system. At early phase of lung injury, NAG treatment results in silenced immune response by targeting ARG1+ macrophages activation, and, consequently, blocks KRT8+ transitional stem cell in the alveolar region to stimulate PDGF Rβ+ fibroblasts hyperproliferation, thereby attenuating the pulmonary fibrosis. This combinational depression of immune response and extracellular matrix deposition within the lung mitigates lung injury and pulmonary fibrosis induced by BLM. Our findings provide novel insight into the protective role of NAG in lung injury.

Polymer-Functionalized Mitochondrial Transplantation to Fibroblasts Counteracts a Pro-Fibrotic Phenotype

Fibroblast-to-myofibroblast transition (FMT) leads to excessive extracellular matrix (ECM) deposition-a well-known hallmark of fibrotic disease. Transforming growth factor-β (TGF-β) is the primary cytokine driving FMT, and this phenotypic conversion is associated with mitochondrial dysfunction, notably a metabolic reprogramming towards enhanced glycolysis. The objective of this study was to examine whether the establishment of favorable metabolic phenotypes in TGF-β-stimulated fibroblasts could attenuate FMT. The hypothesis was that mitochondrial replenishment of TGF-β-stimulated fibroblasts would counteract a shift towards glycolytic metabolism, consequently offsetting pro-fibrotic processes. Isolated mitochondria, functionalized with a dextran and triphenylphosphonium (TPP) (Dex-TPP) polymer conjugate, were administered to fibroblasts (MRC-5 cells) stimulated with TGF-β, and effects on bioenergetics and fibrotic programming were subsequently examined. Results demonstrate that TGF-β stimulation of fibroblasts led to FMT, which was associated with enhanced glycolysis. Dex-TPP-coated mitochondria (Dex-TPP/Mt) delivery to TGF-β-stimulated fibroblasts abrogated a metabolic shift towards glycolysis and led to a reduction in reactive oxygen species (ROS) generation. Importantly, TGF-β-stimulated fibroblasts treated with Dex-TPP/Mt had lessened expression of FMT markers and ECM proteins, as well as reduced migration and proliferation. Findings highlight the potential of mitochondrial transfer, as well as other strategies involving functional reinforcement of mitochondria, as viable therapeutic modalities in fibrosis.

Peptide deregulated in hypertrophic scar-1 alleviates hypertrophic scar fibrosis by targeting focal adhesion kinase and pyruvate kinase M2 and remodeling the metabolic landscape

Hypertrophic scarring is a fibrotic skin disease characterized by excessive deposition of collagens. Emerging evidence has suggested important roles for peptides in fibrosis-related diseases. Here, we demonstrate that a skin-derived endogenous peptide, peptide deregulated in hypertrophic scar-1 (PDHS1), with the sequence IATTTASAATAAAIGATPRAK, inhibits cell proliferation, promotes apoptosis, decreases the proportion of cells in S phase, and decreases collagen synthesis in hypertrophic scar fibroblasts. Additionally, treatment with PDHPS1 alleviates hypertrophic scarring in a rabbit ear model. PDHPS1 was found to bind to focal adhesion kinase (FAK) and to decrease its activity. PDHPS1 was also shown to bind to pyruvate kinase M2 (PKM2) and to decreased its expression. Smad2 phosphorylation is also inhibited by treatment with PDHPS1. Overexpression of FAK rescues the decreased expression of COL3A1 induced by PDHPS1 treatment. Targeted metabolomics revealed that PDHPS1 reprogramed metabolism that related to amino acid synthesis, leading to decreases of the key glycolysis intermediates glucose-6-phosphate and fructose-6-phosphate. These results demonstrated that the endogenous peptide PDHPS1 alleviates hypertrophic scar fibrosis in vitro and in vivo by targeting FAK and PKM2 and remodeling the metabolic landscape. Overall, treatment with PDHPS1 is a potential therapeutic strategy for hypertrophic scarring.

Oxidative Stress and Air Pollution: Its Impact on Chronic Respiratory Diseases

Redox regulation participates in the control of various aspects of metabolism. Reactive oxygen and nitrogen species participate in many reactions under physiological conditions. When these species overcome the antioxidant defense system, a distressed status emerges, increasing biomolecular damage and leading to functional alterations. Air pollution is one of the exogenous sources of reactive oxygen and nitrogen species. Ambient airborne particulate matter (PM) is important because of its complex composition, which includes transition metals and organic compounds. Once in contact with the lungs' epithelium, PM components initiate the synthesis of inflammatory mediators, macrophage activation, modulation of gene expression, and the activation of transcription factors, which are all related to the physiopathology of chronic respiratory diseases, including cancer. Even though the pathophysiological pathways that give rise to the development of distress and biological damage are not fully understood, scientific evidence indicates that redox-dependent signaling pathways are involved. This article presents an overview of the redox interaction of air pollution inside the human body and the courses related to chronic respiratory diseases.