PI3K-Akt-mTOR/PFKFB3 pathway mediated lung fibroblast aerobic glycolysis and collagen synthesis in lipopolysaccharide-induced pulmonary fibrosis

The PI3K-Akt-mTOR pathway mediates renal pericyte-myofibroblast transition by enhancing glycolysis through HKII

BACKGROUND

Pericyte-myofibroblast transition (PMT) has been confirmed to contribute to renal fibrosis in several kidney diseases, and transforming growth factor-β1 (TGF-β1) is a well-known cytokine that drives PMT. However, the underlying mechanism has not been fully established, and little is known about the associated metabolic changes.

METHODS

Bioinformatics analysis was used to identify transcriptomic changes during PMT. PDGFRβ + pericytes were isolated using MACS, and an in vitro model of PMT was induced by 5 ng/ml TGF-β1. Metabolites were analyzed by ultraperformance liquid chromatography (UPLC) and tandem mass spectrometry (MS). 2-Deoxyglucose (2-DG) was used to inhibit glycolysis via its actions on hexokinase (HK). The hexokinase II (HKII) plasmid was transfected into pericytes for HKII overexpression. LY294002 or rapamycin was used to inhibit the PI3K-Akt-mTOR pathway for mechanistic exploration.

RESULTS

An increase in carbon metabolism during PMT was detected through bioinformatics and metabolomics analysis. We first detected increased levels of glycolysis and HKII expression in pericytes after stimulation with TGF-β1 for 48 h, accompanied by increased expression of α-SMA, vimentin and desmin. Transdifferentiation was blunted when pericytes were pretreated with 2-DG, an inhibitor of glycolysis. The phosphorylation levels of PI3K, Akt and mTOR were elevated during PMT, and after inhibition of the PI3K-Akt-mTOR pathway with LY294002 or rapamycin, glycolysis in the TGF-β1-treated pericytes was decreased. Moreover, PMT and HKII transcription and activity were blunted, but the plasmid-mediated overexpression of HKII rescued PMT inhibition.

CONCLUSIONS

The expression and activity of HKII as well as the level of glycolysis were increased during PMT. Moreover, the PI3K-Akt-mTOR pathway regulates PMT by increasing glycolysis through HKII regulation.

Oxymatrine inhibits TGF‑β1‑mediated mitochondrial apoptotic signaling in alveolar epithelial cells via activation of PI3K/AKT signaling

Although pulmonary fibrosis (PF) causes respiratory failure and death, effective therapies for PF have not been developed. Oxymatrine (OMT), an active ingredient in the Chinese herb Sophora flavescens, exerts antifibrotic effects; however, its effect on PF remains unclear. The present study aimed to determine whether OMT decreases transforming growth factor-β1 (TGF-β1)-induced PF in human lung cancer A549 cells by inhibiting apoptosis and targeting the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) pathway. To construct a PF cell model, A549 cells were stimulated with TGF-β1. The experimental groups were as follows: control (untreated cells grown in complete medium), TGF-β1 (cells treated with 5 ng/ml TGF-β1), OMT (cells treated with 5 ng/ml TGF-β1 and 0.25, 0.50, or 1.00 mg/ml OMT), and OMT + LY294002 (cells treated with 5 ng/ml TGF-β1, 1.0 mg/ml OMT. and 25 µmol/l LY294002). The effects of OMT on cell morphology (via electron microscopy), apoptosis (via Annexin V-PI staining), mitochondrial apoptosis signaling [using JC-1 method to analyze mitochondrial membrane potential (MMP)], and Bcl-2, as well as Bax expression (via western blotting and reverse transcription-quantitative polymerase chain reaction), were analyzed. OMT significantly protected cells against TGF-β1-induced PF by inhibiting apoptosis. The specific manifestations were cell injury, as evidenced by morphological changes and decreased MMP. Following OMT treatment, the expression of the pro-apoptotic protein Bax increased, whereas that of the anti-apoptotic protein Bcl-2 decreased. The PI3K/AKT-specific inhibitor LY294002 significantly inhibited the ameliorative effects of OMT on TGF-β1-induced apoptosis. Collectively, OMT attenuated TGF-β1-mediated mitochondrial apoptosis of alveolar epithelial cells by activating the PI3K/AKT signaling pathway. Therefore, OMT may be a promising drug for PF treatment.

Procyanidin B2 Attenuates Sepsis-Induced Acute Lung Injury via Regulating Hippo/Rho/PI3K/NF-κB Signaling Pathway

Acute lung injury (ALI) is a frequent and challenging aspect of sepsis that currently lacks effective treatments. Procyanidin B2 (PB2) has anti-inflammatory and antioxidant properties. The aim of this study was to determine the effectiveness and mechanism of action of PB2 in treating sepsis-induced ALI using animal experiments. A sepsis-induced ALI mouse model was used by administering lipopolysaccharide (LPS) and then evaluating the levels of inflammatory cytokines and lung injury through measurements of cytokine levels using enzyme-linked immunosorbent assay (ELISA), Western blot and real-time PCR, as well as by the examination of relevant signaling pathways. The animal experiments showed that PB2 protected the lungs from injury caused by LPS and reduced the levels of various inflammatory cytokines in both the serum and lung tissue. Western blot analysis showed that PB2 reduced the expression of TLR4/NF-κB and increased the expression of PI3K/Akt, and also inhibited the Hippo and Rho signaling pathways. The results of the study showed that PB2 helps to treat sepsis-induced ALI by controlling cytokine storms and reducing inflammation by altering the expressions of the TLR4/NF-κB, PI3K/Akt, Hippo and Rho signaling pathways. This research provides a foundation for the further investigation of PB2's mechanism and its potential use in treating sepsis.

Qimai Feiluoping decoction inhibits mitochondrial complex I-mediated oxidative stress to ameliorate bleomycin-induced pulmonary fibrosis

BACKGROUND

Qimai Feiluoping decoction (QM), a Traditional Chinese Medicine formula, has been included in rehabilitation program for functional disorders of discharged COVID-19 patients. QM has been proved to effectively improve the clinical symptoms and imaging signs of PF in COVID-19 convalescent patients.

PURPOSE

This study to explore the pharmacological effect of QM against PF from the perspectives of imaging, pathological staining, and molecular mechanisms, and identify possible active components.

METHODS

Micro-CT imaging and immunohistochemical staining were investigated to verify the therapeutic effect of QM in the bleomycin (BLM)-induced PF mouse model. The 4D-label-free proteomics analysis of lung tissues was then conducted to explore the novel mechanisms of QM against PF, which were further validated by a series of experiments. The possible components of QM in plasma and lung tissues were identified with UHPLC/IM-QTOF-MS analysis.

RESULTS

The results from micro-CT imaging and pathological staining revealed that QM treatment can inhibit BLM-induced lung injury, extracellular matrix accumulation and TGF-β expression in the mouse model with PF. The 4D-label-free proteomics analysis demonstrated that the partial subunit proteins of mitochondrial complex I and complex II might be potential targets of QM against PF. Furthermore, QM treatment can inhibit BLM-induced mitochondrial ROS content to promote ATP production and decrease oxidative stress injury in the mouse and cell models of PF, which was mediated by the inhibition of mitochondrial complex I. Finally, a total of 13 protype compounds and 15 metabolites from QM in plasma and lung tissues were identified by UHPLC/IM-QTOF-MS, and liquiritin and isoliquiritigenin from Glycyrrhizae radix et rhizoma could be possible active compounds against PF.

CONCLUSION

It concludes that QM treatment could treat PF by inhibiting mitochondrial complex I-mediated mitochondrial oxidated stress injury, which could offer new insights into the pharmacological mechanisms of QM in the clinical application of PF patients.

A novel prognostic index based on the analysis of glycolysis-related genes in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a lung disease that is both chronic and progressive and is characterized by glycolysis. However, glycolysis's function and its clinical significance in IPF are still not well understood. We accessed the Gene Expression Omnibus database to retrieve mRNA expression information for lung tissue and other samples. We identified genes associated with glycolysis that had differential expression levels between IPF and controls. In this work, we conducted a comprehensive bioinformatic analysis to systematically examine the glycolysis-associated genes with differential expression and subsequently investigated the possible prognostic significance of these genes. Additionally, the expression profiles of the associated prognostic genes were further investigated via quantitative real-time polymerase chain reaction in our cohort. In this investigation, we found that the expression of 16 genes involved in glycolysis was differentially expressed. Among them, 12 were upregulated and 4 were downregulated. We found that 3 glycolysis-related genes (stanniocalcin 2, transketolase like 1, artemin) might serve as hub genes for anticipating patient prognosis. The data from these genes were used to generate the prognostic models. The findings confirmed that high-risk IPF patients recorded a shorter overall survival relative to low-risk patients. This prognostic model yielded 1-, 2-, and 3-year survival rates of 0.666, 0.651, and 0.717, correspondingly, based on the area under the curve of the survival-dependent receiver operating characteristic. The GSE27957 and GSE70866 cohorts validated these findings, indicating the model has a good predictive performance. All 3 glycolysis-associated genes were validated to be expressed in our cohort. Finally, we used mRNA levels from 3 genes to produce a nomogram to quantitatively predict the prognosis of IPF individuals. As possible indicators for the prognosis of IPF, the glycolysis-related genes stanniocalcin 2, transketolase like 1, and artemin were shown to be promising candidate markers.

2-Deoxy-D-Glucose: A Novel Pharmacological Agent for Killing Hypoxic Tumor Cells, Oxygen Dependence-Lowering in Covid-19, and Other Pharmacological Activities

The nonmetabolizable glucose analog 2-deoxy-D-glucose (2-DG) has shown promising pharmacological activities, including inhibition of cancerous cell growth and N-glycosylation. It has been used as a glycolysis inhibitor and as a potential energy restriction mimetic agent, inhibiting pathogen-associated molecular patterns. Radioisotope derivatives of 2-DG have applications as tracers. Recently, 2-DG has been used as an anti-COVID-19 drug to lower the need for supplemental oxygen. In the present review, various pharmaceutical properties of 2-DG are discussed.

PI3K/AKT pathway promotes keloid fibroblasts proliferation by enhancing glycolysis under hypoxia

Our previous study demonstrated altered glucose metabolism and enhanced phosphorylation of the PI3K/AKT pathway in keloid fibroblasts (KFb) under hypoxic conditions. However, whether the PI3K/AKT pathway influences KFb cell function by regulating glucose metabolism under hypoxic conditions remains unclear. Here, we show that when PI3K/AKT pathway was inactivated with LY294002, the protein expression of glycolytic enzymes decreased, while the amount of mitochondria and mitochondrial membrane potential increased. The key parameters of extracellular acidification rate markedly diminished, and those of oxygen consumption rate significantly increased after inhibition of the PI3K/AKT pathway. When the PI3K/AKT pathway was suppressed, the levels of reactive oxygen species (ROS) and mitochondrial ROS (mitoROS) were significantly increased. Meanwhile, cell proliferation, migration and invasion were inhibited, and apoptosis was increased when the PI3K/AKT pathway was blocked. Additionally, cell proliferation was compromised when KFb were treated with both SC79 (an activator of the PI3K/AKT pathway) and 2-deoxy-d-glucose (an inhibitor of glycolysis), compared with the SC79 group. Moreover, a positive feedback mechanism was demonstrated between the PI3K/AKT pathway and hypoxia-inducible factor-1α (HIF-1α). Our data collectively demonstrated that the PI3K/AKT pathway promotes proliferation and inhibits apoptosis in KFb under hypoxia by regulating glycolysis, indicating that the PI3K/AKT signalling pathway could be a therapeutic target for keloids.

Docosahexaenoic acid administration improves diabetes-induced cardiac fibrosis through enhancing fatty acid oxidation in cardiac fibroblast

Diabetes mellitus can lead to various complications, including organ fibrosis. Metabolic remodeling often occurs during the development of organ fibrosis. Docosahexaenoic acid (DHA), an essential ω-3 polyunsaturated fatty acid, shows great benefits in improving cardiovascular disease and organ fibrosis, including regulating cellular metabolism. In this study, we investigated whether DHA can inhibit diabetes-induced cardiac fibrosis by regulating the metabolism of cardiac fibroblasts. Type I diabetic mice were induced by streptozotocin and after supplementation with DHA for 16 weeks, clinical indicators of serum and heart were evaluated. DHA administration significantly improved serum lipid levels, cardiac function and cardiac interstitial fibrosis, but not blood glucose levels. Subsequently, immunofluorescences, western blot and label-free quantitative proteomics methods were used to study the mechanism. The results showed that the anti-fibrotic function of DHA was achieved through regulating extracellular matrix homeostasis including ECM synthesis and degradation. Our research demonstrated DHA regulated the energy metabolism of cardiac fibroblasts, especially fatty acid oxidation, and then affected the balance of ECM synthesis and degradation. It suggested that DHA supplementation could be considered an effective adjuvant therapy for cardiac fibrosis caused by hyperglycemia.

Therapeutic effects of selective p300 histone acetyl-transferase inhibitor on liver fibrosis

Liver fibrosis is caused by chronic liver damage and results in the aberrant accumulation of extracellular matrix during disease progression. Despite the identification of the HAT enzyme p300 as a major factor for liver fibrosis, the development of therapeutic agents targeting the regulation of p300 has not been reported. We validated a novel p300 inhibitor (A6) on the improvement of liver fibrosis using two mouse models, mice on a choline-deficient high-fat diet and thioacetamide-treated mice. We demonstrated that pathological hall-marks of liver fibrosis were significantly diminished by A6 treatment through Masson's trichrome and Sirius red staining on liver tissue and found that A6 treatment reduced the expression of matricellular protein genes. We further showed that A6 treatment improved liver fibrosis by reducing the stability of p300 protein via disruption of p300 binding to AKT. Our findings suggest that targeting p300 through the specific inhibitor A6 has potential as a major therapeutic avenue for treating liver fibrosis. [BMB Reports 2023; 56(2): 114-119].

Glycolytic reprogramming is involved in tissue remodeling on chronic rhinosinusitis

BACKGROUND

Glycolytic reprogramming is a key feature of chronic inflammatory disease. Extracellular matrix (ECM) produced by myofibroblasts plays an important role in tissue remodeling of nasal mucosa in chronic rhinosinusitis (CRS). This study aimed to determine whether glycolytic reprogramming contributes to myofibroblast differentiation and ECM production in nasal fibroblasts.

METHODS

Primary nasal fibroblasts were isolated from the nasal mucosa of patients with CRS. Glycolytic reprogramming was assessed by measuring the extracellular acidification and oxygen consumption rates in nasal fibroblast, with and without transforming growth factor beta 1 (TGF-β1) treatment. Expression of glycolytic enzymes and ECM components was measured by real-time polymerase chain reaction, western blotting, and immunocytochemical staining. Gene set enrichment analysis was performed using whole RNA-sequencing data of nasal mucosa of healthy donors and patients with CRS.

RESULT

Glycolysis of nasal fibroblasts stimulated with TGF-B1 was upregulated along with glycolytic enzymes. Hypoxia-inducing factor (HIF)-1α was a high-level regulator of glycolysis, and increased HIF-1α expression promoted glycolysis of nasal fibroblasts, and inhibition of HIF-1α down-regulated myofibroblasts differentiation and ECM production.

CONCLUSION

This study suggests that inhibition of the glycolytic enzyme and HIF-1α in nasal fibroblasts regulates myofibroblast differentiation and ECM generation associated with nasal mucosa remodeling.

Hexokinase 2-mediated glycolysis supports inflammatory responses to Porphyromonas gingivalis in gingival fibroblasts

BACKGROUND

When infected with Porphyromonas gingivalis, gingival fibroblasts undergo metabolic reprogramming, and rely on aerobic glycolysis rather than oxidative phosphorylation for rapid energy replenishment. Hexokinases (HKs) are catalysts for glucose metabolism, and HK2 constitutes the major HK inducible isoform. The objective of this study is to determine whether HK2-mediated glycolysis promotes inflammatory responses in inflamed gingiva.

METHODS

Levels of glycolysis-related genes were assessed in normal and inflamed gingiva. Human gingival fibroblasts were harvested and infected with Porphyromonas gingivalis in order to mimic periodontal inflammation. 2-deoxy-d-glucose, an analogue of glucose, was used to block HK2-mediated glycolysis, while small interfering RNA was used to knock down HK2 expression. The mRNA and protein levels of genes were analyzed by real-time quantitative PCR and western blotting, respectively. HK2 activity and lactate production were assessed by ELISA. Cell proliferation was assessed by confocal microscopy. The generation of reactive oxygen species was assessed by flow cytometry.

RESULTS

Elevated expression of HK2 and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 was observed in the inflamed gingiva. P. gingivalis infection was shown to promote glycolysis in human gingival fibroblasts, as evidenced by increased gene transcription of HK2 and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3, cell glucose consumption, and HK2 activity. Inhibition and knockdown of HK2 resulted in reduced cytokine production, cell proliferation, and reactive oxygen species generation. Furthermore, P. gingivalis infection activated the hypoxia-inducible factor-1α signaling pathway, thus promoting HK2-mediated glycolysis and proinflammatory responses.

CONCLUSIONS

HK2-mediated glycolysis promotes inflammatory responses in gingival tissues, and therefore glycolysis can be targeted in order to inhibit the progression of periodontal inflammation.

Therapeutic effects of selective p300 histone acetyl-transferase inhibitor on liver fibrosis

Liver fibrosis is caused by chronic liver damage and results in the aberrant accumulation of extracellular matrix during disease progression. Despite the identification of the HAT enzyme p300 as a major factor for liver fibrosis, the development of therapeutic agents targeting the regulation of p300 has not been reported. We validated a novel p300 inhibitor (A6) on the improvement of liver fibrosis using two mouse models, mice on a choline-deficient high-fat diet and thioacetamide-treated mice. We demonstrated that pathological hall-marks of liver fibrosis were significantly diminished by A6 treatment through Masson's trichrome and Sirius red staining on liver tissue and found that A6 treatment reduced the expression of matricellular protein genes. We further showed that A6 treatment improved liver fibrosis by reducing the stability of p300 protein via disruption of p300 binding to AKT. Our findings suggest that targeting p300 through the specific inhibitor A6 has potential as a major therapeutic avenue for treating liver fibrosis. [BMB Reports 2023; 56(2): 114-119].

Neutrophil extracellular traps and pulmonary fibrosis: an update

Pulmonary fibrosis (PF) is a serious and often fatal illness that occurs in various clinical settings and represents a significant unmet medical need. Increasing evidence indicates that neutrophil extracellular traps (NETs) contribute significantly to the progression of PF. Therefore, understanding the pathways by which NETs contribute to the disease is crucial for developing effective treatments. This review focuses on the formation of NETs and the common mechanisms of NETs in PF.

Alamandine/MrgD axis prevents TGF-β1-mediated fibroblast activation via regulation of aerobic glycolysis and mitophagy

BACKGROUND

Idiopathic pulmonary fibrosis is a chronic progressive, lethal disease in which ectopic lung fibroblast (LF) activation plays a vital part. We have previously shown that alamandine (ALA) exerts anti-fibrosis effects via the MAS-related G-protein coupled receptor D (MrgD). Here, we further investigate how it moderates transforming growth factor β1 (TGF-β1)-induced LF activation by regulating glucose metabolism and mitochondria autophagy (mitophagy).

METHODS

In vitro, we examined glycolysis-related protein hexokinase 2 (HK2), 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3), and lactic acid in cells treated with TGF-β1. The oxygen consumption rate and the extracellular acidification rate were detected using Seahorse assays. Then, mitophagy was evaluated using transmission electron microscopy, mt-Keima, and the co-localization of Parkin and COX IV with LC3 and LAMP1, respectively. The autophagic degradation of HK2 and PFKFB3 was detected by 3MA and bafilomycin A1 and assessed by their co-localization with LC3 and LAMP1, respectively. The effects of ALA on LF activation markers collagen I and α-SMA were detected. The effects of ALA on glucose metabolism, mitophagy, and the activation of LF were also investigated in vivo.

RESULTS

We found that the ALA/MrgD axis improved TGF-β1-mediated LF activation by repressing glycolysis by downregulating HK2 and PFKFB3 expression. Lactic acid sustained positive feedback between glycolysis and LF activation by maintaining the expression of HK2 and PFKFB3. We also showed that glycolysis enhancement resulted from blocking the autophagic degradation of HK2 and PFKFB3 while upregulated mRNA levels by TGF-β1, while all of those improved by ALA adding. Importantly, we determined that moderation of Parkin/LC3-mediated mitophagy by TGF-β1 also promotes glycolysis but is reversed by ALA. Furthermore, we proved that ALA counteracts the effects of bleomycin on HK2, PFKFB3, LC3, Parkin, and LF activation in vivo.

CONCLUSION

In this study, we show that the ALA/MrgD axis prevents TGF-β1-mediated fibroblast activation via regulation of aerobic glycolysis and mitophagy.

Curcumae Rhizoma: A botanical drug against infectious diseases

Curcumae Rhizoma is the dry rhizome coming from Curcuma longa L. which grow widely in tropical south and southwest Asia. It has been used to treat conditions such as dermatoses, infections, stress, and depression. Moreover, in China, Curcumae Rhizoma and its active constituents have been made into different pharmaceutical preparations. Growing evidence suggests that these preparations can exert antioxidant, anti-inflammatory, and anti-cancer effects, which may play crucial roles in the treatment of various diseases, including cancer, infectious-, autoimmune-, neurological-, and cardiovascular diseases, as well as diabetes. The anti-infective effect of Curcumae Rhizoma has become a popular field of research around the world, including for the treatment of COVID-19, influenza virus, hepatitis B virus, human immunodeficiency virus, and human papilloma virus, among others. In this paper, the basic characteristics of Curcumae Rhizoma and its active constituents are briefly introduced, and we also give an overview on their applications and mechanisms in infectious diseases.

Huashibaidu formula attenuates sepsis-induced acute lung injury via suppressing cytokine storm: Implications for treatment of COVID-19

BACKGROUND

Acute lung injury (ALI) is a common complication of sepsis with poor effective interventions. Huashibaidu formula (HSBD) showed good therapeutic effects in treating coronavirus disease 2019 (COVID-19) patients.

PURPOSE

This study was designed to investigate the therapeutic potential and precise mechanism of HSBD against sepsis-induced ALI based on network pharmacology and animal experiments.

MATERIALS AND METHODS

Network pharmacology was used to predict the possible mechanism of HSBD against sepsis. Next, a sepsis-induced ALI rat model via intraperitoneal lipopolysaccharide (LPS) was constructed to evaluate the level of inflammatory cytokines and the degree of lung injury. The expression of inflammation-related signaling pathways, including TLR4/NF-κB and PI3K/Akt was determined by western blot.

RESULTS

Network pharmacology analysis indicated that HSBD might have a therapeutic effect on sepsis mainly by affecting inflammatory and immune responses. Animal experiments demonstrated that HSBD protected the lung tissue from LPS-induced injury, and inhibited the levels of inflammatory cytokines such as interleukin (IL)-1β, granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon (IFN)-γ and tumor necrosis factor (TNF)-α in the serum and IL-1β, IL-5, IL-6, IL-18, GM-CSF, IFN-γ and TNF-α in the lung tissue. Western blot results revealed that HSBD downregulated the expression of TLR4/NF-κB and upregulated the expression of PI3K/Akt.

CONCLUSION

The therapeutic mechanism of HSBD against sepsis-induced ALI mainly involved suppressing cytokine storms and relieving inflammatory symptoms by regulating the expression of TLR4/NF-κB and PI3K/Akt. Our study provides a scientific basis for the mechanistic investigation and clinical application of HSBD in the treatment of sepsis and COVID-19.

Nicorandil mitigates amiodarone-induced pulmonary toxicity and fibrosis in association with the inhibition of lung TGF-β1/PI3K/Akt1-p/mTOR axis in rats

The long-term side effect of the antiarrhythmic drug, amiodarone (AMIO), such as lung toxicity, remains a critical clinical issue. The previous knowledge denotes diverse antioxidant, anti-inflammatory, and antifibrotic properties of the anti-anginal drug, nicorandil (NI). Therefore, we aimed to investigate the possible protective effect of NI on pulmonary tissue remodelling following AMIO-induced lung toxicity. The included rats were assigned into four equal groups (n = 8): (1) control, (2) control group that received NI 10 mg kg^-1  day^-1 , (3) model group that received AMIO in a dose of 60 mg kg^-1  day^-1 , and (4) treated group (AMIO-NI) that were treated with AMIO plus NI as shown above. Drug administration continued for 10 weeks. AMIO resulted in deteriorated (p < 0.001) pulmonary functions accompanied by respiratory acidosis. AMIO showed an obvious histological injury score with intense collagen deposition, disturbed nitric oxide synthase enzymes (NOS/iNOS), and increased alpha smooth muscle actin expression. Furthermore, AMIO upregulated the transforming growth factor (TGF-β1)/phosphoinositide-3 kinase (PI3K)-Akt1-p/mammalian target of rapamycin (mTOR) axis, which determined the possible mechanism of AMIO on pulmonary remodelling. NI treatment significantly (p < 0.001) prevented the AMIO-induced lung toxicity, as well as inhibited the TGF-β1/PI3K/Akt1-p/mTOR axis in the lung tissue of rats. The results were confirmed by an in-vitro study. CONCLUSION: The current results revealed that NI was effective in preserving the lung structure and functions. Amelioration of the oxidative stress and modulation of TGF-β1/PI3K/Akt1-p/mTOR have been achieved. This study suggests NI administration as a preventive therapy from the serious pulmonary fibrosis side effect of AMIO.

Integrin β3 Mediates Sepsis and Mechanical Ventilation-Associated Pulmonary Fibrosis Through Glycometabolic Reprogramming

Mechanical ventilation (MV) has become a clinical first-line treatment option for patients with respiratory failure. However, it was unclear whether MV further aggravates the process of sepsis-associated pulmonary fibrosis and eventually leads to sepsis and mechanical ventilation-associated pulmonary fibrosis (S-MVPF). This study aimed to explore the mechanism of S-MVPF concerning integrin β3 activation in glycometabolic reprogramming of lung fibroblasts. We found that MV exacerbated sepsis-associated pulmonary fibrosis induced by lipopolysaccharide, which was accompanied by proliferation of lung fibroblasts, increased deposition of collagen in lung tissue, and increased procollagen type I carboxy-terminal propeptide in the bronchoalveolar lavage fluid. A large number of integrin β3- and pyruvate kinase M2-positive fibroblasts were detected in lung tissue after stimulation with lipopolysaccharide and MV, with an increase in lactate dehydrogenase A expression and lactate levels. S-MVPF was primarily attenuated in integrin β3-knockout mice, which also resulted in a decrease in the levels of pyruvate kinase M2, lactate dehydrogenase A, and lactate. In conclusion, MV aggravated sepsis-associated pulmonary fibrosis, with glycometabolic reprogramming mediated by integrin β3 activation. Thus, integrin β3-mediated glycometabolic reprogramming might be a potential therapeutic target for S-MVPF.

The significance of glycolysis in tumor progression and its relationship with the tumor microenvironment

It is well known that tumor cells rely mainly on aerobic glycolysis for energy production even in the presence of oxygen, and glycolysis is a known modulator of tumorigenesis and tumor development. The tumor microenvironment (TME) is composed of tumor cells, various immune cells, cytokines, and extracellular matrix, among other factors, and is a complex niche supporting the survival and development of tumor cells and through which they interact and co-evolve with other tumor cells. In recent years, there has been a renewed interest in glycolysis and the TME. Many studies have found that glycolysis promotes tumor growth, metastasis, and chemoresistance, as well as inhibiting the apoptosis of tumor cells. In addition, lactic acid, a metabolite of glycolysis, can also accumulate in the TME, leading to reduced extracellular pH and immunosuppression, and affecting the TME. This review discusses the significance of glycolysis in tumor development, its association with the TME, and potential glycolysis-targeted therapies, to provide new ideas for the clinical treatment of tumors.

Intracellular galectin-3 is a lipopolysaccharide sensor that promotes glycolysis through mTORC1 activation

How the carbohydrate binding protein galectin-3 might act as a diabetogenic and tumorogenic factor remains to be investigated. Here we report that intracellular galectin-3 interacts with Rag GTPases and Ragulator on lysosomes. We show that galectin-3 senses lipopolysaccharide (LPS) to facilitate the interaction of Rag GTPases and Ragulator, leading to the activation of mTORC1. We find that the lipopolysaccharide/galectin-3-Rag GTPases/Ragulator-mTORC1 axis regulates a cohort of genes including GLUT1, and HK2, and PKM2 that are critically involved in glucose uptake and glycolysis. Indeed, galectin-3 deficiency severely compromises LPS-promoted glycolysis. Importantly, the expression of HK2 is significantly reduced in diabetes patients. In multiple types of cancer including hepatocellular carcinoma (HCC), galectin-3 is highly expressed, and its level of expression is positively correlated with that of HK2 and PKM2 and negatively correlated with the prognosis of HCC patients. Our study unravels that galectin-3 is a sensor of LPS, an important modulator of the mTORC1 signaling, and a critical regulator of glucose metabolism.

The role of autophagy in idiopathic pulmonary fibrosis: from mechanisms to therapies

Idiopathic pulmonary fibrosis (IPF) is an interstitial pulmonary disease with an extremely poor prognosis. Autophagy is a fundamental intracellular process involved in maintaining cellular homeostasis and regulating cell survival. Autophagy deficiency has been shown to play an important role in the progression of pulmonary fibrosis. This review focused on the six steps of autophagy, as well as the interplay between autophagy and other seven pulmonary fibrosis related mechanisms, which include extracellular matrix deposition, myofibroblast differentiation, epithelial-mesenchymal transition, pulmonary epithelial cell dysfunction, apoptosis, TGF-β1 pathway, and the renin-angiotensin system. In addition, this review also summarized autophagy-related signaling pathways such as mTOR, MAPK, JAK2/STAT3 signaling, p65, and Keap1/Nrf2 signaling during the development of IPF. Furthermore, this review also illustrated the commonly used autophagy detection methods, the currently approved antifibrotic drugs pirfenidone and nintedanib, and several prospective compounds targeting autophagy for the treatment of IPF.

Metabolic reprogramming of pulmonary fibrosis

Pulmonary fibrosis is a progressive and intractable lung disease with fibrotic features that affects alveoli elasticity, which leading to higher rates of hospitalization and mortality worldwide. Pulmonary fibrosis is initiated by repetitive localized micro-damages of the alveolar epithelium, which subsequently triggers aberrant epithelial-fibroblast communication and myofibroblasts production in the extracellular matrix, resulting in massive extracellular matrix accumulation and interstitial remodeling. The major cell types responsible for pulmonary fibrosis are myofibroblasts, alveolar epithelial cells, macrophages, and endothelial cells. Recent studies have demonstrated that metabolic reprogramming or dysregulation of these cells exerts their profibrotic role via affecting pathological mechanisms such as autophagy, apoptosis, aging, and inflammatory responses, which ultimately contributes to the development of pulmonary fibrosis. This review summarizes recent findings on metabolic reprogramming that occur in the aforementioned cells during pulmonary fibrosis, especially those associated with glucose, lipid, and amino acid metabolism, with the aim of identifying novel treatment targets for pulmonary fibrosis.

MYBPC3 deficiency in cardiac fibroblasts drives their activation and contributes to fibrosis

Genetic mutations in the MYBPC3 gene encoding cardiac myosin binding protein C (cMyBP-C) are the most common cause of hypertrophic cardiomyopathy (HCM). Myocardial fibrosis (MF) plays a critical role in the development of HCM. However, the mechanism for mutant MYBPC3-induced MF is not well defined. In this study, we developed a R495Q mutant pig model using cytosine base editing and observed an early-onset MF in these mutant pigs shortly after birth. Unexpectedly, we found that the "cardiac-specific" MYBPC3 gene was actually expressed in cardiac fibroblasts from different species as well as NIH3T3 fibroblasts at the transcription and protein levels. CRISPR-mediated disruption of Mybpc3 in NIH3T3 fibroblasts activated nuclear factor κB (NF-κB) signaling pathway, which increased the expression of transforming growth factor beta (TGF-β1) and other pro-inflammatory genes. The upregulation of TGF-β1 promoted the expression of hypoxia-inducible factor-1 subunit α (HIF-1α) and its downstream targets involved in glycolysis such as GLUT1, PFK, and LDHA. Consequently, the enhanced aerobic glycolysis with higher rate of ATP biosynthesis accelerated the activation of cardiac fibroblasts, contributing to the development of HCM. This work reveals an intrinsic role of MYBPC3 in maintaining cardiac fibroblast homeostasis and disruption of MYBPC3 in these cells contributes to the disease pathogenesis of HCM.

MK-2206 Alleviates Renal Fibrosis by Suppressing the Akt/mTOR Signaling Pathway In Vivo and In Vitro

Renal fibrosis is a common pathological feature of various kidney diseases, leading to irreversible renal failure and end-stage renal disease. However, there are still no effective treatments to reverse renal fibrosis. This study aimed to explore the potential mechanism of a targeted drug for fibrosis. Here, unilateral ureteral obstruction (UUO)-treated mice and a TGF-β1-treated human renal tubular epithelial cell line (HK-2 cells) were used as models of renal fibrosis. Based on the changes of mRNA in UUO kidneys detected by transcriptome sequencing, MK-2206, an Akt inhibitor, was predicted as a potential drug to alleviate renal fibrosis through bioinformatics. We dissolved UUO mice with MK-2206 by gastric gavage and cultured TGF-β-induced HK-2 cells with MK-2206. Histopathological examinations were performed after MK-2206 intervention, and the degree of renal fibrosis, as well as the expression of Akt/mTOR pathway-related proteins, were evaluated by immunohistochemical staining, immunofluorescence staining, and Western blot. The results showed that MK-2206 significantly improved the pathological structure of the kidney. Furthermore, MK-2206 intervention effectively inhibited UUO- and TGF-β1-induced epithelial-mesenchymal transition, fibroblast activation, and extracellular matrix deposition. Mechanistically, MK-2206 treatment attenuated the activation of the Akt/mTOR signaling pathway. Taken together, our study revealed for the first time that MK-2206 is a promising drug for the improvement of renal fibrosis.

MicroRNA let-7f-5p regulates PI3K/AKT/COX2 signaling pathway in bacteria-induced pulmonary fibrosis via targeting of PIK3CA in forest musk deer

Background

Recent studies have characterized that microRNA (miRNA) is a suitable candidate for the study of bleomycin/LPS-induced pulmonary fibrosis, but the knowledge on miRNA in bacteria-induced pulmonary fibrosis (BIPF) is limited. Forest musk deer (Moschus berezovskii, FMD) is an important endangered species that has been seriously affected by BIPF. We sought to determine whether miRNA exist that modulates the pathogenesis of BIPF in FMD.

Methods

High-throughput sequencing and RT-qPCR were used to determine the differentially expressed miRNAs (DEmiRNAs) in the blood of BIPF FMD. The DEmiRNAs were further detected in the blood and lung of BIPF model rat by RT-qPCR, and the targeting relationship between candidate miRNA and its potential target gene was verified by dual-luciferase reporter activity assay. Furthermore, the function of the candidate miRNA was verified in the FMD lung fibroblast cells (FMD-C1).

Results

Here we found that five dead FMD were suffered from BIPF, and six circulating miRNAs (miR-30g, let-7f-5p, miR-27-3p, miR-25-3p, miR-9-5p and miR-652) were differentially expressed in the blood of the BIPF FMD. Of these, let-7f-5p showed reproducibly lower level in the blood and lung of the BIPF model rat, and the expression levels of PI3K/AKT/COX2 signaling pathway genes (PIK3CA, PDK1, Akt1, IKBKA, NF-κB1 and COX2) were increased in the lung of BIPF model rats, suggesting that there is a potential correlation between BIPF and the PI3K/AKT/COX2 signaling pathway. Notably, using bioinformatic prediction and experimental verification, we demonstrated that let-7f-5p is conserved across mammals, and the seed sequence of let-7f-5p displays perfect complementarity with the 3' UTR of PIK3CA gene and the expression of the PIK3CA gene was regulated by let-7f-5p. In order to determine the regulatory relationship between let-7f-5p and the PI3K/AKT/COX2 signaling pathway in FMD, we successfully cultured FMD-C1, and found that let-7f-5p could act as a negative regulator for the PI3K/Akt/COX2 signaling pathway in FMD-C1. Collectively, this study not only provided a study strategy for non-invasive research in pulmonary disease in rare animals, but also laid a foundation for further research in BIPF.

The Use of Metabolomics as a Tool to Compare the Regulatory Mechanisms in the Cecum, Ileum, and Jejunum in Healthy Rabbits and with Diarrhea

Simple Summary

The problems caused by antibiotic abuse have swept the world, and the Chinese government has responded to calls for a comprehensive ban on antibiotics. However, not using antibiotics also challenges China’s existing livestock industry. Based on this, we carried out a nontargeted metabolomics analysis of the jejunum, ileum, and cecum of diarrhea rabbits and normal rabbits fed with antibiotic-free diets, respectively, to find out the mechanism of action of each intestinal segment group and between different intestinal segments. The screened differential metabolites were mostly related to intestinal barrier, intestinal inflammation, and autophagy after a KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis. In this paper, we analyzed the metabolic pathways that were significantly different between different intestinal segments and illustrated the mechanism and potential connections of the screened differential metabolites in different intestinal segments in the form of charts.

Abstract

For many years, antibiotics in feed have been an effective and economical means to promote growth and disease resistance in livestock production. However, the rampant abuse of antibiotics has also brought very serious harm to human health and the environment. Therefore, the Chinese government promulgated laws and regulations on 1 July 2020, to prohibit the use of antibiotics in feed. To improve the effect of antibiotic-free feeding on China’s existing rabbit industry, we used the nontargeted metabolomics method to detect the differences between diarrhea rabbits (Dia) and normal rabbits (Con) on an antibiotic-free diet. A total of 1902 different metabolites were identified. A KEGG analysis showed that in the cecum, metabolites were mainly concentrated in bile secretion, antifolate resistance, aldosterone synthesis, and secretion pathways. The ileal metabolites were mainly concentrated in tyrosine metabolism, phenylalanine, tyrosine and tryptophan biosynthesis, steroid hormone biosynthesis, alanine, aspartate, and glutamate metabolism. The metabolites in the jejunum were mainly rich in panquinone and other terpenoid compound quinone biosynthesis, AMPK (adenosine 5′-monophosphate (AMP)-activated protein kinase) signal, inositol phosphate metabolism, and pentose phosphate pathway. After a deep excavation of the discovered differential metabolites and metabolic pathways with large differences between groups, it was found that these metabolic pathways mainly involved intestinal inflammation, intestinal barrier, and autophagy. The results showed that panquinone and other terpenoids could increase AMPK activity to promote cell metabolism and autophagy, thus trying to prevent inflammation and alleviate intestinal disease symptoms. In addition, we discussed the possible reasons for the changes in the levels of seven intestinal endogenous metabolites in rabbits in the diarrhea group. The possibility of improving diarrhea by adding amino acids to feed was discussed. In addition, the intermediate products produced by the pentose phosphate pathway and coenzyme Q had a positive effect on steroid hormone biosynthesis to combat intestinal inflammation.

The Pro-Fibrotic Response to Lens Injury Is Signaled in a PI3K Isoform-Specific Manner

The signaling inputs that function to integrate biochemical and mechanical cues from the extracellular environment to alter the wound-repair outcome to a fibrotic response remain poorly understood. Here, using a clinically relevant post-cataract surgery wound healing/fibrosis model, we investigated the role of Phosphoinositide-3-kinase (PI3K) class I isoforms as potential signaling integrators to promote the proliferation, emergence and persistence of collagen I-producing alpha smooth muscle actin (αSMA+) myofibroblasts that cause organ fibrosis. Using PI3K isoform specific small molecule inhibitors, our studies revealed a requisite role for PI3K p110α in signaling the CD44+ mesenchymal leader cell population that we previously identified as resident immune cells to produce and organize a fibronectin-EDA rich provisional matrix and transition to collagen I-producing αSMA+ myofibroblasts. While the PI3K effector Akt was alone insufficient to regulate myofibroblast differentiation, our studies revealed a role for Rac, another potential PI3K effector, in this process. Our studies further uncovered a critical role for PI3K p110α in signaling the proliferation of CD44+ leader cells, which is important to the emergence and expansion of myofibroblasts. Thus, these studies identify activation of PI3K p110α as a critical signaling input following wounding to the development and progression of fibrotic disease.

Metabolic reprogramming consequences of sepsis: adaptations and contradictions

During sepsis, the importance of alterations in cell metabolism is underappreciated. The cellular metabolism, which has a variable metabolic profile in different cells and disease stages, is largely responsible for the immune imbalance and organ failure associated with sepsis. Metabolic reprogramming, in which glycolysis replaces OXPHOS as the main energy-producing pathway, is both a requirement for immune cell activation and a cause of immunosuppression. Meanwhile, the metabolites produced by OXPHOS and glycolysis can act as signaling molecules to control the immune response during sepsis. Sepsis-induced "energy shortage" leads to stagnated cell function and even organ dysfunction. Metabolic reprogramming can alleviate the energy crisis to some extent, enhance host tolerance to maintain cell survival functions, and ultimately increase the adaptation of cells during sepsis. However, a switch from glycolysis to OXPHOS is essential for restoring cell function. This review summarized the crosstalk between metabolic reprogramming and immune cell activity as well as organ function during sepsis, discussed the benefits and drawbacks of metabolic reprogramming to show the contradictions of metabolic reprogramming during sepsis, and assessed the feasibility of treating sepsis through targeted metabolism. Using metabolic reprogramming to achieve metabolic homeostasis could be a viable therapy option for sepsis.

Role of glycolysis in the development of atherosclerosis

Atherosclerosis is a chronic inflammatory vascular disease associated with atherosclerotic plaques and endothelial dysfunction, inflammation, and plaque formation. Glycolysis is a conservative and rigorous biological process that decomposes glucose into pyruvate. Its function is to provide the body with energy and intermediate products required for life activities. However, abnormalities in glycolytic flux during the progression of atherosclerosis accelerate disease progression. Here, we review the role of glycolysis in the development of atherosclerosis to provide new ideas for developing novel anti-atherosclerosis strategies.

The Apelin-APJ axis alleviates LPS-induced pulmonary fibrosis and endothelial mesenchymal transformation in mice by promoting Angiotensin-Converting Enzyme 2

Fibrotic alterations resulting from abnormal tissue repair after lung injury are responsible for the high mortality observed after acute respiratory distress syndrome. Therefore, the prevention and treatment of pulmonary fibrosis has been widely concerned. The Apelin-APJ axis plays an important role in the prevention and treatment of respiratory diseases and organ fibrosis. However, its underlying mechanism remains to be further studied. The aim of this study was to investigate whether the anti-pulmonary fibrosis effect of apelin-APJ axis is related to the activation of angiotensin-converting Enzyme 2 (ACE2). Here, we found that exogenous activation of the Apelin-APJ axis alleviates lipopolysaccharide (LPS)-induced pulmonary fibrosis in mice. In vitro studies revealed that Apelin-13 inhibited LPS-induced endothelial mesenchymal transition in lung microvascular endothelial cells, whereas [Ala13]-Apelin-13 (Apelin-APJ axis inhibitor) accelerated LPS-induced endothelial interstitial transformation in lung microvascular endothelial cells. Notably, angiotensin-converting enzyme 2 (ACE2) inhibitor blocks the beneficial effect of the Apelin-APJ axis activation on LPS-induced pulmonary fibrosis. This finding suggests that the Apelin-APJ axis inhibits pulmonary fibrosis by activating ACE2. Simultaneously, accumulating evidence suggests that ubiquitination may contribute to pulmonary fibrosis. Our study found that LPS increased the ubiquitination of ACE2 protein, whereas Apelin-13 inhibited it. In conclusion, exogenous activation of the Apelin-APJ axis improves LPS-induced pulmonary fibrosis in mice and may be a viable therapeutic target for pulmonary fibrosis.

Revealing the mechanism of Jiegeng decoction attenuates bleomycin-induced pulmonary fibrosis via PI3K/Akt signaling pathway based on lipidomics and transcriptomics

BACKGROUND

Pulmonary fibrosis (PF) is a serious lung disease with unknown etiology and irreversible course. Jiegeng decoction (JGD), a traditional prescription, is widely used to treat lung diseases due to its anti-inflammatory and expectorant effects.

PURPOSE

To explore the effect of JGD on mice with PF and its underlying mechanism. For this purpose, we established a mouse model with PF by bleomycin (BLM) and then administered JGD and pirfenidone at different concentrations.

RESULTS

In vivo, JGD was found to reduce lung inflammation, improve lung function and decrease collagen deposition to alleviate bleomycin-induced PF in mice. The mouse lung tissue was analyzed using lipidomics and transcriptomics. We found phosphatidylinositol was decreased after JGD treatment in lipidomics results, while transcriptomics results showed the critical roles of PI3K/Akt signaling pathway in JGD treatment group. Then, Western Blot and Immunohistochemistry were used to validate that JGD may regulate the expression of Bax, Caspase3, Caspase8, Caspase9 and Bcl-2 apoptosis-related proteins via PI3K/Akt signaling pathway. TUNEL staining revealed that apoptosis mainly occurs on AEC IIs.

CONCLUSION

Our results showed that JGD inhibits apoptosis through the PI3K/Akt signaling pathway, thereby protecting against BLM-induced PF. Hence, JGD is expected to be a potential drug candidate for the treatment of PF.

DDR1 promotes LoVo cell proliferation by regulating energy metabolism

Cellular energy metabolism dysregulation is associated with colorectal cancer (CRC) development and progression. Discoidin domain receptor 1a (DDR1a), one of the five DDR1 isoforms, is closely related to cell proliferation, invasion, and apoptosis in various tumors. Whether it participates in cellular metabolic reprogramming and regulates CRC initiation and progression remains unclear. In this study, we compared the expression of DDR1 in CRC tissues and adjacent tissues from 126 postoperative CRC samples. Moreover, lentivirus-mediated DDR1a overexpression and knockdown were performed in LoVo cells, and cell viability and proliferation were determined by CCK-8 and BrdU assays, respectively. Oxygen consumption rate, extracellular acidification rate, and lactate production were used to determine the effect of DDR1a on metabolic reprogramming. Clinically, CRC patients with high DDR1 expression had poor differentiation and were at an advanced TNM stage. DDR1a promoted LoVo cell proliferation, mitochondrial function, and extracellular acidification. Moreover, DDR1a knockdown inhibited intracellular lactic acid production in LoVo cells, while a pyruvate kinase inhibitor (diamide, 200 μM) significantly reversed this progression. Taken together, our results reveal that DDR1 plays a crucial role in maintaining intracellular environment homeostasis through metabolic reprogramming.

A New Hypothetical Concept in Metabolic Understanding of Cardiac Fibrosis: Glycolysis Combined with TGF-β and KLF5 Signaling

The accumulation of fibrosis in cardiac tissues is one of the leading causes of heart failure. The principal cellular effectors in cardiac fibrosis are activated fibroblasts and myofibroblasts, which serve as the primary source of matrix proteins. TGF-β signaling pathways play a prominent role in cardiac fibrosis. The control of TGF-β by KLF5 in cardiac fibrosis has been demonstrated for modulating cardiovascular remodeling. Since the expression of KLF5 is reduced, the accumulation of fibrosis diminishes. Because the molecular mechanism of fibrosis is still being explored, there are currently few options for effectively reducing or reversing it. Studying metabolic alterations is considered an essential process that supports the explanation of fibrosis in a variety of organs and especially the glycolysis alteration in the heart. However, the interplay among the main factors involved in fibrosis pathogenesis, namely TGF-β, KLF5, and the metabolic process in glycolysis, is still indistinct. In this review, we explain what we know about cardiac fibroblasts and how they could help with heart repair. Moreover, we hypothesize and summarize the knowledge trend on the molecular mechanism of TGF-β, KLF5, the role of the glycolysis pathway in fibrosis, and present the future therapy of cardiac fibrosis. These studies may target therapies that could become important strategies for fibrosis reduction in the future.

Soluble CD163 is produced by monocyte-derived and alveolar macrophages, and is not associated with the severity of idiopathic pulmonary fibrosis

The soluble form of the membrane hemoglobin scavenger receptor CD163 (sCD163), released by shedding, is a strong marker for macrophage activation. Serum sCD163 levels rise in several acute inflammatory states and some fibrosing diseases. Monocyte-derived macrophages (MoDM) differentiated by macrophage colony-stimulating factor (M-MoDM) contribute to the pathophysiology of idiopathic pulmonary fibrosis (IPF), an irreversible and rapidly fatal interstitial lung disease. Since M-MoDM express high membrane CD163 levels, we thus postulated that sCD163 could be a relevant biomarker for macrophage activation in IPF. We found that M-MoDM constitutively released higher amounts of sCD163 (49.5 ± 24.5 ng/ml) than monocytes (0.45 ± 0.32 ng/ml) or MoDM differentiated with granulocyte macrophage-stimulating factor (2.24 ± 0.98 ng/ml). The basal production of sCD163 by M-MoDM was increased following stimulation with lipopolysaccharide (123.4 ± 54.9 ng/ml) or ATP (168.9 ± 41.8 ng/ml). The sCD163 release was controlled by metalloproteases but not through ADAM17 activation. Moreover, CD163-positive macrophages and sCD163 were detected in pulmonary tissues and alveolar fluids of Caucasian patients with IPF, respectively. IPF alveolar macrophages constitutively secreted sCD163 amounts (67.6 ± 44.6 ng/µg RNA) which were significantly higher than those released by alveolar macrophages isolated from controls (19.2 ± 7.6 ng/µg RNA) or patients with other interstitial lung disease (31.5 ± 16.6 ng/µg RNA). However, the concentrations of sCD163 in blood serum collected from 155 patients with IPF did not correlate with the severity of their disease. In conclusion, our results show that M-MoDM constituted a pertinent model to study the regulation of sCD163 production. Yet, serum sCD163 values could not provide a prognostic biomarker for IPF in our cohort.

The role of macrophage-fibroblast interaction in lipopolysaccharide-induced pulmonary fibrosis: an acceleration in lung fibroblast aerobic glycolysis

Recent evidence has shown that lipopolysaccharide (LPS)-induced aerobic glycolysis of lung fibroblasts is closely associated with the pathogenesis of septic pulmonary fibrosis. Nevertheless, the underlying mechanism remains poorly defined. In this study, we demonstrate that LPS promotes c-Jun N-terminal kinase (JNK) signaling pathway activation and endogenous tumor necrosis factor-α (TNF-α) secretion in pulmonary macrophages. This, in turn, could significantly promote aerobic glycolysis and increase lactate production in lung fibroblasts through 6-phosphofructo-2-kinase/fructose-2, 6-biphosphatase 3 (PFKFB3) activation. Culturing human lung fibroblast MRC-5 cell line with TNF-α or endogenous TNF-α (cell supernatants of macrophages after LPS stimulation) both enhanced the aerobic glycolysis and increased lactate production. These effects could be prevented by treating macrophages with JNK pathway inhibitor, by administering TNF-α receptor 1 (TNFR1) siRNA, PFKFB3 inhibitor, or by silencing PFKFB3 with fibroblasts-specific shRNA. In addition, the inhibition of TNF-α secretion and PFKFB3 expression prevented LPS-induced pulmonary fibrosis in vivo. In conclusion, this study revealed that LPS-induced macrophage secretion of TNF-α could initiate fibroblast aerobic glycolysis and lactate production, implying that inflammation-metabolism interactions between lung macrophages and fibroblasts might play an essential role in LPS-induced pulmonary fibrosis.

PI3K Signaling in Mechanisms and Treatments of Pulmonary Fibrosis Following Sepsis and Acute Lung Injury

Pulmonary fibrosis is a pathological fibrotic process affecting the lungs of five million people worldwide. The incidence rate will increase even more in the next years due to the long-COVID-19 syndrome, but a resolving treatment is not available yet and usually prognosis is poor. The emerging role of the phosphatidylinositol 3-kinase (PI3K)/AKT signaling in fibrotic processes has inspired the testing of drugs targeting the PI3K/Akt pathway that are currently under clinical evaluation. This review highlights the progress in understanding the role of PI3K/Akt in the development of lung fibrosis and its causative pathological context, including sepsis as well as acute lung injury (ALI) and its consequent acute respiratory distress syndrome (ARDS). We further summarize current knowledge about PI3K inhibitors for pulmonary fibrosis treatment, including drugs under development as well as in clinical trials. We finally discuss how the design of inhaled compounds targeting the PI3K pathways might potentiate efficacy and improve tolerability.

The role of SHMT2 in modulating lipid metabolism in hepatocytes via glycine-mediated mTOR activation

Serine hydroxymethyltransferase 2 (SHMT2) converts serine into glycine in the mitochondrial matrix, transferring a methyl group to tetrahydrofolate. SHMT2 plays an important role in the maintenance of one-carbon metabolism. Previously, we found a negative correlation between the serine concentration and the progression of fatty liver disease (FLD). However, little is known about the role of SHMT2 in hepatic lipid metabolism. We established SHMT2 knockdown (KD) mouse primary hepatocytes using RNA interference to investigate the role of SHMT2 in lipid metabolism. SHMT2 KD hepatocytes showed decreased lipid accumulation with reduced glycine levels compared to the scramble cells, which was restored upon reintroducing SHMT2. SHMT2 KD hepatocytes showed downregulation of the mTOR/PPARɣ pathway with decreased gene expression related to lipogenesis and fatty acid uptake. Pharmacological activation of mTOR or PPARɣ overexpression blocked the inhibitory effect of SHMT2 KD on lipid accumulation. We also showed that glycine activated mTOR/PPARɣ signaling and identified glycine as a mediator of SHMT2-responsive lipid accumulation in hepatocytes. In conclusion, silencing SHMT2 in hepatocytes ameliorates lipid accumulation via the glycine-mediated mTOR/PPARɣ pathway. Our findings underscore the possibility of SHMT2 as a therapeutic target of FLD.

miR-193a-3p increases glycolysis under hypoxia by facilitating Akt phosphorylation and PFKFB3 activation in human macrophages

Human macrophages infiltrating hypoxic regions alter their metabolism, because oxygen becomes limited. Increased glycolysis is one of the most common cellular adaptations to hypoxia and mostly is regulated via hypoxia-inducible factor (HIF) and RAC-alpha serine/threonine–protein kinase (Akt) signaling, which gets activated under reduced oxygen content. We noticed that micro RNA (miR)-193a-3p enhances Akt phosphorylation at threonine 308 under hypoxia. In detail, miR-193a-3p suppresses the protein abundance of phosphatase PTC7 homolog (PPTC7), which in turn increases Akt phosphorylation. Lowering PPTC7 expression by siRNA or overexpressing miR-193a-3p increases Akt phosphorylation. Vice versa, inhibition of miR-193a-3p attenuates Akt activation and prevents a subsequent increase of glycolysis under hypoxia. Excluding effects of miR-193a-3p and Akt on HIF expression, stabilization, and function, we noticed phosphorylation of 6 phosphofructo-2-kinase/fructose 2,6-bisphosphatase PFKFB3 in response to the PI3K/Akt/mTOR signaling cascade. Inhibition of PFKFB3 blocked an increased glycolytic flux under hypoxia. Apparently, miR-193a-3p balances Akt phosphorylation and dephosphorylation by affecting PPTC7 protein amount. Suppression of PPTC7 increases Akt activation and phosphorylation of PFKFB3, which culminates in higher rates of glycolysis under hypoxia.

Targeting PI3K/AKT signaling for treatment of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive fibrotic interstitial pneumonia with unknown causes. The incidence rate increases year by year and the prognosis is poor without cure. Recently, phosphatidylinositol 3-kinase (PI3K)/protein kinase B (PKB/AKT) signaling pathway can be considered as a master regulator for IPF. The contribution of the PI3K/AKT in fibrotic processes is increasingly prominent, with PI3K/AKT inhibitors currently under clinical evaluation in IPF. Therefore, PI3K/AKT represents a critical signaling node during fibrogenesis with potential implications for the development of novel anti-fibrotic strategies. This review epitomizes the progress that is being made in understanding the complex interpretation of the cause of IPF, and demonstrates that PI3K/AKT can directly participate to the greatest extent in the formation of IPF or cooperate with other pathways to promote the development of fibrosis. We further summarize promising PI3K/AKT inhibitors with IPF treatment benefits, including inhibitors in clinical trials and pre-clinical studies and natural products, and discuss how these inhibitors mitigate fibrotic progression to explore possible potential agents, which will help to develop effective treatment strategies for IPF in the near future.

Molecular mechanisms underlying the role of hypoxia-inducible factor-1 α in metabolic reprogramming in renal fibrosis

Renal fibrosis is the result of renal tissue damage and repair response disorders. If fibrosis is not effectively blocked, it causes loss of renal function, leading to chronic renal failure. Metabolic reprogramming, which promotes cell proliferation by regulating cellular energy metabolism, is considered a unique tumor cell marker. The transition from oxidative phosphorylation to aerobic glycolysis is a major feature of renal fibrosis. Hypoxia-inducible factor-1 α (HIF-1α), a vital transcription factor, senses oxygen status, induces adaptive changes in cell metabolism, and plays an important role in renal fibrosis and glucose metabolism. This review focuses on the regulation of proteins related to aerobic glycolysis by HIF-1α and attempts to elucidate the possible regulatory mechanism underlying the effects of HIF-1α on glucose metabolism during renal fibrosis, aiming to provide new ideas for targeted metabolic pathway intervention in renal fibrosis.

Dihydroartemisinin inhibits Lewis Lung carcinoma progression by inducing macrophages M1 polarization via AKT/mTOR pathway

Preclinical and clinical data show a close relationship between high infiltration of tumor-associated macrophages (TAMs) and a poor prognosis in most types of tumors, thus targeting TAMs stands out as promising anticancer immunotherapies. Recent studies have demonstrated the anti-tumor effects of artemisinin via enhancing anti-tumor immunity within tumor microenvironment, but the underlying mechanism is still not clear. In the present study we uncovered an important role of dihydroartemisinin (DHA) in regulating intratumoral TAM polarization and anti-tumor immune responses in mouse Lewis Lung carcinoma model. We found that DHA inhibited Lewis Lung carcinoma progress, moderately decreased the frequencies of TAMs within tumor stroma, and significantly increased CD86 expression while decreased CD206 expression on TAMs which indicates the role of DHA in polarizing TAMs into a M1-like phenotype. Then, our in vitro data confirmed that DHA dose-dependently promoted macrophage M1 phenotype transition by increasing M1 phenotype-related molecules, meanwhile decreasing the expression of M2 phenotype-related molecules. In addition, DHA increased proinflammatory cytokine production, enhanced the phagocytic capacity while decreased anti-inflammatory cytokine production. Finally, in order to prove that AKT/mTOR signaling potentially mediated DHA-induced macrophage differentiation, we used rapamycin to specifically block the activity of mTOR and stimulated macrophages under M1 stimuli. Our data clearly showed that rapamycin significantly decreased DHA-induced M1-related phenotypes and proinflammatory cytokine expression. In summary, our study highlighted DHA as one of future potential therapeutic options for the development of novel anticancer immunotherapies in lung cancer.

Pseudomonas aeruginosa PcrV Enhances the Nitric Oxide-Mediated Tumoricidal Activity of Tumor-Associated Macrophages via a TLR4/PI3K/AKT/mTOR-Glycolysis-Nitric Oxide Circuit

Tumor-associated macrophages (TAMs), which display a tumor-supportive M2 phenotype, are closely related to tumor growth and metastasis. The reprogramming of TAMs toward a tumoricidal M1 profile has emerged as an attractive strategy for cancer immunotherapy. In this study, we found that the intratumoral injection of PcrV protein, a component of the Pseudomonas aeruginosa type 3 secretion system, suppressed tumor growth and increased apoptosis, inducible nitric oxide synthase (iNOS) expression, and the percentage of M1-polarized TAMs in tumor tissues. Furthermore, the intratumoral injection of PcrV-primed macrophages exerted a similar tumoricidal effect. In vitro analyses revealed that PcrV reeducated TAMs toward an antitumoral M1 phenotype and augmented their nitric oxide (NO)-mediated cytotoxicity against cancer cells. Mechanistically, we found that these effects were dependent on the activation of Toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88)-mediated regulation of a PI3K/AKT/mTOR-glycolysis-NO feedback loop via direct interaction with TLR4. Collectively, these results revealed a potential role for PcrV in cancer immunotherapy through the targeting of TAM plasticity.

Control of Tissue Fibrosis by 5-Methoxytryptophan, an Innate Anti-Inflammatory Metabolite

Tissue fibrosis causes debilitating human diseases such as liver cirrhosis, heart failure, chronic kidney disease and pulmonary insufficiency. It is a dynamic process orchestrated by specific subsets of monocyte-macrophages, fibroblasts, pericytes and hepatic stellate cells. Fibrosis is linked to tissue inflammation. Pro-inflammatory macrophages promote fibrosis by driving myofibroblast differentiation and macrophage myofibroblast transition. Myofibroblasts express α-smooth muscle cell actin (α-SMA) and secrete extracellular matrix (ECM) proteins notably collagen I and III. Deposition of ECM proteins at injury sites and interstitial tissues distorts normal structure and impairs vital functions. Despite advances in the mechanisms of fibrosis at cellular, molecular and genetic levels, prevention and treatment of fibrotic diseases remain poorly developed. Recent reports suggest that 5-methoxytryptophan (5-MTP) is effective in attenuating injury-induced liver, kidney, cardiac and pulmonary fibrosis. It inhibits macrophage activation and blocks fibroblast differentiation to myofibroblasts. Furthermore, it inhibits hepatic stellate cell differentiation into myofibroblasts. As 5-MTP is an endogenous molecule derived from tryptophan catabolism via tryptophan hydroxylase pathway, it is well-suited as a lead compound for developing new anti-fibrotic drugs. This article provides an overview of 5-MTP synthesis, and a critical review of its anti-fibrotic activities. Its mechanisms of actions and potential therapeutic value will be discussed.

Glycolysis Inhibition Alleviates Cardiac Fibrosis After Myocardial Infarction by Suppressing Cardiac Fibroblast Activation

Objective: To explore the role of glycolysis in cardiac fibroblast (CF) activation and cardiac fibrosis after myocardial infarction (MI).

Method:In vivo: 2-Deoxy-D-glucose (2-DG), a glycolysis inhibitor, was injected into the abdominal cavity of the MI or sham mice every day. On the 28th day, cardiac function was measured by ultrasonic cardiography, and the hearts were harvested. Masson staining and immunofluorescence (IF) were used to evaluate the fibrosis area, and western blot was used to identify the glycolytic level. In vitro, we isolated the CF from the sham, MI and MI with 2-DG treatment mice, and we also activated normal CF with transforming growth factor-β1 (TGF-β1) and block glycolysis with 2-DG. We then detected the glycolytic proteins, fibrotic proteins, and the concentrations of lactate and glucose in the culture medium. At last, we further detected the fibrotic and glycolytic markers in human fibrotic and non-fibrotic heart tissues with masson staining, IF and western blot.

Result: More collagen and glycolytic protein expressions were observed in the MI mice hearts. The mortality increased when mice were treated with 2-DG (100 mg/kg/d) after the MI surgery (Log-rank test, P < 0.05). When the dosage of 2-DG declined to 50 mg/kg/d, and the treatment was started on the 4th day after MI, no statistical difference of mortality between the two groups was observed (Log-rank test, P = 0.98). The collagen volume fraction was smaller and the fluorescence signal of α-smooth muscle actin (α-SMA) was weaker in mice treated with 2-DG than PBS. In vitro, 2-DG could significantly inhibit the increased expression of both the glycolytic and fibrotic proteins in the activated CF.

Conclusion: Cardiac fibrosis is along with the enhancement of CF activation and glycolysis. Glycolysis inhibition can alleviate cardiac fibroblast activation and cardiac fibrosis after myocardial infarction.

Anlotinib Inhibits PFKFB3-Driven Glycolysis in Myofibroblasts to Reverse Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal disease in which the normal alveolar network is gradually replaced by fibrotic scars. Current evidence suggests that metabolic alterations correlate with myofibroblast activation in IPF. Anlotinib has been proposed to have antifibrotic effects, but the efficacy and mechanisms of anlotinib against lung fibrosis have not been systematically evaluated. The antifibrotic effects of anlotinib were evaluated in bleomycin-induced mouse models and transforming growth factor-beta 1 (TGF-β1)-stimulated lung fibroblasts. We measured lactate levels, 2-NBDG glucose uptake and the extracellular acidification rate (ECAR) to assess glycolysis in fibroblasts. RNA-protein coimmunoprecipitation (RIP) and polysome analyses were performed to investigate novel mechanisms of glycolytic reprogramming in pulmonary fibrosis. We found that anlotinib diminished myofibroblast activation and inhibited the augmentation of glycolysis. Moreover, we show that PCBP3 posttranscriptionally increases PFKFB3 expression by promoting its translation during myofibroblast activation, thus promoting glycolysis in myofibroblasts. Regarding mechanism, anlotinib exerts potent antifibrotic effects by downregulating PCBP3, reducing PFKFB3 translation and inhibiting glycolysis in myofibroblasts. Furthermore, we observed that anlotinib had preventative and therapeutic antifibrotic effects on bleomycin-induced pulmonary fibrosis. Therefore, we identify PCBP3 as a protein involved in the regulation of glycolysis reprogramming and lung fibrogenesis and propose it as a therapeutic target for pulmonary fibrosis. Our data suggest that anlotinib has antifibrotic effects on the lungs, and we provide a novel mechanism for this effect. Anlotinib may constitute a novel and potent candidate for the treatment of pulmonary fibrosis.

Backstage players of fibrosis: NOX4, mTOR, HDAC, and S1P; companions of TGF-β

The fibrotic process could be easily defined as a pathological excess of extracellular matrix deposition, leading to disruption of tissue architecture and eventually loss of function; however, this process involves a complex network of several signal transduction pathways. Virtually almost all organs could be affected by fibrosis, the most affected are the liver, lung, skin, kidney, heart, and eyes; in all of them, the transforming growth factor-beta (TGF-β) has a central role. The canonical and non-canonical signal pathways of TGF-β impact the fibrotic process at the cellular and molecular levels, inducing the epithelial-mesenchymal transition (EMT) and the induction of profibrotic gene expression with the consequent increase in proteins such as alpha-smooth actin (α-SMA), fibronectin, collagen, and other extracellular matrix proteins. Recently, it has been reported that some molecules that have not been typically associated with the fibrotic process, such as nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 4 (NOX4), mammalian target of rapamycin (mTOR), histone deacetylases (HDAC), and sphingosine-1 phosphate (S1P); are critical in its development. In this review, we describe and discuss the role of these new players of fibrosis and the convergence with TGF-β signaling pathways, unveiling new insights into the panorama of fibrosis that could be useful for future therapeutic targets.

Asiatic acid alleviates Ang-II induced cardiac hypertrophy and fibrosis via miR-126/PIK3R2 signaling

Background

Cardiac hypertrophy is an independent risk factor of many cardiovascular diseases. Studies have demonstrated that microRNA-126 (miR-126) was involved in angiogenesis during physiological and pathological process. However, its role in cardiac hypertrophy has not been known clearly. Our previous study demonstrated that asiatic acid (AA) has obvious protective effect on cardiac hypertrophy. Here, this study aimed to discover the regulatory role of miR-126 and its mechanism in cardiac hypertrophy, and to determine whether AA’s anti-hypertrophy effect is partially miR-126 dependent.

Methods

Male Sprague Dawley rats were AngII infused via osmotic minipumps for 4 weeks and were treated with AA (20 mg/kg/day) by oral gavage. Cardiac hypertrophy was assessed using the echocardiography and histological analysis. In vitro studies,cardiomyocyte and cardiac fibroblasts (CF) were treted with AngII and AngII plus AA. And, the effect of AA on miR-126 and PI3K/AKT signaling pathway was investigated.

Results

Treatment of rats with AA decreased the ratio of heart weight to tibia length and hypertrophy markers. In vitro exprements demonstrated that AA significantly attenuated AngII-induced cardiac growth and cardiac fibroblast collagen expression. Moreover, our results found downregulation of miR-126 and activation of PI3K/AKT signaling pathway in AngII infusion induced cardiac hypertrophy model. It was also determined that miR-126 targets PIK3R2 directly.

Conclusions

AA supplementation upregulated the expression of miR-126 and conferred cardio-protection effect against AngII induced cardiac hypertrophy.