Peroxisome proliferator‐activated receptor gamma coactivator‐1α/HSF1 axis effectively alleviates lipopolysaccharide‐induced acute lung injury via suppressing oxidative stress and inflammatory response

Sodium Houttuyniae attenuates ferroptosis by regulating TRAF6-c-Myc signaling pathways in lipopolysaccharide-induced acute lung injury (ALI)

The impact of Sodium Houttuyniae (SH) on lipopolysaccharide (LPS)-induced ALI has been investigated extensively. However, it remains ambiguous whether ferroptosis participates in this process. This study aimed to find out the impacts and probable mechanisms of SH on LPS-induced ferroptosis. A rat ALI model and type II alveolar epithelial (ATII) cell injury model were treated with LPS. Enzyme-linked immunosorbent assay (ELISA), hematoxylin-eosin (HE) staining, and Giemsa staining were executed to ascertain the effects of SH on LPS-induced ALI. Moreover, Transmission electron microscopy, Cell Counting Kit-8 (CCK8), ferrous iron colorimetric assay kit, Immunohistochemistry, Immunofluorescence, Reactive oxygen species assay kit, western blotting (Wb), and qRT-PCR examined the impacts of SH on LPS-induced ferroptosis and ferroptosis-related pathways. Theresults found that by using SH treatment, there was a remarkable attenuation of ALI by suppressing LPS-induced ferroptosis. Ferroptosis was demonstrated by a decline in the levels of glutathione peroxidase 4 (GPX4), FTH1, and glutathione (GSH) and a surge in the accumulation of malondialdehyde (MDA), reactive oxygen species (ROS), NOX1, NCOA4, and Fe2+, and disruption of mitochondrial structure, which were reversed by SH treatment. SH suppressed ferroptosis by regulating TRAF6-c-Myc in ALI rats and rat ATII cells. The results suggested that SH treatment attenuated LPS-induced ALI by repressing ferroptosis, and the mode of action can be linked to regulating the TRAF6-c-Myc signaling pathway in vivo and in vitro.

Predictive value of serum MED1 and PGC-1α for bronchopulmonary dysplasia in preterm infants

OBJECTIVE

This study aimed to predict the bronchopulmonary dysplasia (BPD) in preterm infants with a gestational age(GA) < 32 weeks utilizing clinical data, serum mediator complex subunit 1 (MED1), and serum peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC-1α).

METHODS

This prospective observational study enrolled 70 preterm infants with GA < 32 weeks. The infants were categorized into two groups: non-BPD group(N = 35) and BPD group(N = 35), including 25 cases with mild BPD and 10 patients with moderate/severe subgroups. We performed multifactorial regression analysis to investigate the postnatal risk factors for BPD. Furthermore, we compared serum levels of biomarkers, including MED1 and PGC-1α, among infants with and without BPD at postnatal days 1, 7, 14, 28, and PMA 36 weeks. A logistic regression model was constructed to predict BPD's likelihood using clinical risk factors and serum biomarkers.

RESULTS

Serum levels of MED1 on the first postnatal day, PGC-1α on the 1st, 7th, and 28th days, and PMA at 36 weeks were significantly lower in the BPD group than in the non-BPD group (P < 0.05). Furthermore, the predictive model for BPD was created by combing serum levels of MED1 and PGC-1α on postnatal day 1 along with clinical risk factors such as frequent apnea, mechanical ventilation time > 7 d, and time to reach total enteral nutrition. Our predictive model had a high predictive accuracy(C statistics of 0.989) .

CONCLUSION

MED1and PGC-1α could potentially serve as valuable biomarkers, combined with clinical factors, to aid clinicians in the early diagnosis of BPD.

LPS-induced monocarboxylate transporter-1 inhibition facilitates lactate accumulation triggering epithelial-mesenchymal transformation and pulmonary fibrosis

The epithelial-mesenchymal transformation (EMT) process of alveolar epithelial cells is recognized as involved in the development of pulmonary fibrosis. Recent evidence has shown that lipopolysaccharide (LPS)-induced aerobic glycolysis of lung tissue and elevated lactate concentration are associated with the pathogenesis of sepsis-associated pulmonary fibrosis. However, it is uncertain whether LPS promotes the development of sepsis-associated pulmonary fibrosis by promoting lactate accumulation in lung tissue, thereby initiating EMT process. We hypothesized that monocarboxylate transporter-1 (MCT1), as the main protein for lactate transport, may be crucial in the pathogenic process of sepsis-associated pulmonary fibrosis. We found that high concentrations of lactate induced EMT while moderate concentrations did not. Besides, we demonstrated that MCT1 inhibition enhanced EMT process in MLE-12 cells, while MCT1 upregulation could reverse lactate-induced EMT. LPS could promote EMT in MLE-12 cells through MCT1 inhibition and lactate accumulation, while this could be alleviated by upregulating the expression of MCT1. In addition, the overexpression of MCT1 prevented LPS-induced EMT and pulmonary fibrosis in vivo. Altogether, this study revealed that LPS could inhibit the expression of MCT1 in mouse alveolar epithelial cells and cause lactate transport disorder, which leads to lactate accumulation, and ultimately promotes the process of EMT and lung fibrosis.

Tamoxifen induced cardiac damage via the IL-6/p-STAT3/PGC-1α pathway

Tamoxifen (TAM) is an effective anticancer drug for breast and ovarian cancer. However, increased risk of cardiotoxicity is a long-term clinical problem associated with TAM, while the underlying mechanisms remain unclear. Here, we performed experiments in cardiomyocytes and tumor-bearing or nontumor-bearing mice, and demonstrated that TAM induced cardiac injury via the IL-6/p-STAT3/PGC-1α/IL-6 feedback loop, which is responsible for reactive oxygen species (ROS) accumulation. Compared with non-tumor bearing mice, tumor-bearing mice showed stronger cardiac toxicity after TAM injection, although there was no significant difference. In vitro experiments demonstrated STAT3 phosphorylation inhibitor can increase PGC-1α expression and protect cardiomyocyte via decreasing ROS. Since tumor has higher STAT3 phosphorylation and IL-6 expression level, our research results indicated combining TAM and STAT3 inhibitor might be an effective treatment strategy which can provide both tumor killing and cardioprotective function. Further in vivo research is needed to fully elucidate the effect and mechanisms of the combination therapy of TAM and STAT3 inhibitor.

The role of the Gas6/TAM signal pathway in the LPS-induced pulmonary epithelial cells injury

BACKGROUND

Acute lung injury (ALI) is an acute inflammatory respiratory disease. The interaction between growth arrest-specific 6 (Gas6) and tyrosine kinases of the Tyro3, Axl, Mer (TAM) family plays an important role in a variety of physiological and pathological processes, including inflammation. In this study, we mainly clarified the mechanism of the Gas6/TAM signal pathway in lipopolysaccharide (LPS)-induced pulmonary epithelial cells (BEAS-2B cells) injury.

METHODS

We cultured BEAS-2B cells in vitro and established a LPS-induced BEAS-2B cells injury model. Then, the siRNA sequence (siGas6-2) was transfected into cells. The expression of Gas6/TAM was measured based on quantitative reverse transcription polymerase chain reaction (qRT-RCR) and western blot (WB). Cell proliferation and apoptosis were measured by cell counting Kit-8 (CCK-8) and flow cytometry. The expression of pro-inflammatory factors was measured by qRT-RCR and WB.

RESULTS

Our study showed that when the 40 μg/mL LPS-induced BEAS-2B cells injury model was established, cell viability was significantly reduced, but the Gas6/TAM signal pathway was activated. When transfection with siGas6-2, low expression of Gas6 directly reduced the expression of downstream TAM receptors. Furthermore, the inhibition of the Gas6/TAM signal pathway significantly reduced the occurrence of cell apoptosis and the expression of inflammatory factors, and promoted cell proliferation.

CONCLUSION

Our research indicated that Gas6/TAM played an important role in cell proliferation, apoptosis, and inflammatory response in the LPS-induced BEAS-2B cells injury, and Gas6/TAM may be a new target in the treatment of ALI in the future.

Nutri-stress, mitochondrial dysfunction, and insulin resistance-role of heat shock proteins

Excess nutrient flux into the cellular energy system results in a scenario of cellular metabolic stress in diseases involving insulin resistance, such as type 2 diabetes, referred to as nutri-stress and results in cellular bioenergetic imbalance, which leads to insulin resistance and disease. Under nutri-stress, the heat shock response system is compromised due to metabolic abnormalities that disturb energy homeostasis. Heat shock proteins (HSPs) are the chief protectors of intracellular homeostasis during stress. Heat shock response (HSR) impairment contributes to several metabolic pathways that aggravate chronic hyperglycaemia and insulin resistance, highlighting a central role in disease pathogenesis. This article discusses the role of nutri-stress-related molecular events in causing insulin resistance and the nature of the roles played by heat shock proteins in some of the crucial checkpoints of the molecular networks involved in insulin resistance. Ample evidence suggests that the heat shock machinery regulates critical pathways in mitochondrial function and energy metabolism and that cellular energy status highly influences it. Weakening of HSPs, therefore, leads to loss of their vital cytoprotective functions, propagating nutri-stress in the system. Further research into the mechanistic roles of HSPs in metabolic homeostasis will help widen our understanding of lifestyle diseases, their onset, and complications. These inducible proteins may be crucial to attenuating lifestyle risk factors and disease management.

Can PPAR γ Keep Cadmium in Check?

Cd, a naturally occurring endocrine toxin found in tobacco leaves, originates in the environment and enters the body through inhalation, targeting the lungs and kidneys. A study published by Larsen-Carey et al. revealed that cadmium mediates the persistence of classically activated lung macrophages to exacerbate lung injury. The research discovered a novel role for PPAR γ as an effective regulator for the alternative activation of macrophages in response to Cd and Cd-induced lung injury.

HSF1 Protects Sepsis-Induced Acute Lung Injury by Inhibiting NLRP3 Inflammasome Activation

As an important transcription factor, heat shock factor 1 (HSF1) plays an endogenous anti-inflammation role in the body and can alleviate multiple organ dysfunction caused by sepsis, which contributes to an uncontrolled inflammatory response. The NLRP3 inflammasome is a supramolecular complex that plays key roles in immune surveillance. Inflammation is accomplished by NLRP3 inflammasome activation, which leads to the proteolytic maturation of IL-1β and pyroptosis. However, whether HSF1 is involved in the activation of the NLRP3 inflammasome in septic acute lung injury (ALI) has not been reported. Here, we show that HSF1 suppresses NLRP3 inflammasome activation in transcriptional and post-translational modification levels. HSF1 can repress NLRP3 expression via inhibiting NF-κB phosphorylation. HSF1 can inhibit caspase-1 activation and IL-1β maturation via promoting NLRP3 ubiquitination. Our finding not only elucidates a novel mechanism for HSF1-mediated protection of septic ALI but also identifies new therapeutic targets for septic ALI and related diseases.

Crosstalk of pyroptosis, ferroptosis, and mitochondrial aldehyde dehydrogenase 2-related mechanisms in sepsis-induced lung injury in a mouse model

Acute lung injury (ALI) is a common complication of sepsis. Mitochondrial aldehyde dehydrogenase 2 (ALDH2), an enzyme involved in aldehyde metabolism, exerts a protective effect against sepsis. This study investigated the possible mechanisms underlying the roles of ALDH2, pyroptosis, and ferroptosis in sepsis-induced lung injury. A mouse model of sepsis-induced lung injury was established by cecal ligation and puncture (CLP); lung morphology was evaluated by calculation of lung coefficient, hematoxylin–eosin staining, and electron microscopy. Malondialdehyde (MDA), reactive oxygen species (ROS), and 4-hydroxy-2-nonenal (4-HNE) protein expression levels were used to detect the level of lipid oxidative stress. In addition, total iron was detected using an iron detection kit, and the expression of ferroptosis-related proteins (PTGS2, GPX4), pyroptosis-related proteins, and ALDH2 was examined using western blotting. To further examine the likely mechanisms, the ferroptosis inhibitor ferrostatin 1 (Fer-1), NLRP3 inflammasome inhibitor MCC950, and ALDH2 activator Alda-1 were added. CLP-treated mice exhibited destruction of lung tissue morphology, lipid peroxidation injury, iron content, and increased lung PTGS2 protein expression, accompanied by a decrease in GPX4 protein expression. CLP also downregulated ALDH2 expression and increased the expression of the NLRP3 inflammasome and pyroptosis-related proteins. These adverse effects of CLP were relieved by Alda-1, Fer-1, and MCC950 treatment. In conclusion, both pyroptosis and ferroptosis participate in CLP-induced ALI, and ALDH2 plays a protective role by reducing pyroptosis and ferroptosis. This study provides a scientific basis for the treatment of lung injury in sepsis.

Mechanism of the switch from NO to H2O2 in endothelium-dependent vasodilation in diabetes

Coronary microvascular dysfunction is prevalent among people with diabetes and is correlated with cardiac mortality. Compromised endothelial-dependent dilation (EDD) is an early event in the progression of diabetes, but its mechanisms remain incompletely understood. Nitric oxide (NO) is the major endothelium-dependent vasodilatory metabolite in the healthy coronary circulation, but this switches to hydrogen peroxide (H₂O₂) in coronary artery disease (CAD) patients. Because diabetes is a significant risk factor for CAD, we hypothesized that a similar NO-to-H₂O₂ switch would occur in diabetes. Vasodilation was measured ex vivo in isolated coronary arteries from wild type (WT) and microRNA-21 (miR-21) null mice on a chow or high-fat/high-sugar diet, and B6.BKS(D)-Lepr^db/J (db/db) mice using myography. Myocardial blood flow (MBF), blood pressure, and heart rate were measured in vivo using contrast echocardiography and a solid-state pressure sensor catheter. RNA from coronary arteries, endothelial cells, and cardiac tissues was analyzed via quantitative real-time PCR for gene expression, and cardiac protein expression was assessed via western blot analyses. Superoxide was detected via electron paramagnetic resonance. (1) Ex vivo coronary EDD and in vivo MBF were impaired in diabetic mice. (2) Nω-Nitro-L-arginine methyl ester, an NO synthase inhibitor (L-NAME), inhibited ex vivo coronary EDD and in vivo MBF in WT. In contrast, polyethylene glycol-catalase, an H₂O₂ scavenger (Peg-Cat), inhibited diabetic mouse EDD ex vivo and MBF in vivo. (3) miR-21 was upregulated in diabetic mouse endothelial cells, and the deficiency of miR-21 prevented the NO-to-H₂O₂ switch and ameliorated diabetic mouse vasodilation impairments. (4) Diabetic mice displayed increased serum NO and H₂O₂, upregulated mRNA expression of Sod1, Sod2, iNos, and Cav1, and downregulated Pgc-1α in coronary arteries, but the deficiency of miR-21 reversed these changes. (5) miR-21-deficient mice exhibited increased cardiac PGC-1α, PPARα and eNOS protein and reduced endothelial superoxide. (6) Inhibition of PGC-1α changed the mRNA expression of genes regulated by miR-21, and overexpression of PGC-1α decreased the expression of miR-21 in high (25.5 mM) glucose treated coronary endothelial cells. Diabetic mice exhibit a NO-to-H₂O₂ switch in the mediator of coronary EDD, which contributes to microvascular dysfunction and is mediated by miR-21. This study represents the first mouse model recapitulating the NO-to-H₂O₂ switch seen in CAD patients in diabetes.

HSF1-Dependent Autophagy Activation Contributes to the Survival of Melanocytes Under Oxidative Stress in Vitiligo

Autophagy plays a protective role in oxidative stress‒induced melanocyte death. Dysregulated autophagy increases the sensitivity of melanocytes in response to oxidative damage and promotes melanocyte degeneration in vitiligo. However, the molecular mechanism underlying this process is not fully understood. In this study, using RNA-sequencing technology, we compared the transcriptome change between normal and vitiligo melanocytes with or without treatment of oxidative stress. We found that ATG5 and ATG12, the critical components for autophagosome formation, were significantly reduced in vitiligo melanocytes under oxidative stress. Mechanistically, HSF1 is the prime transcription factor for both ATG5 and ATG12, accounting for the reduced level of ATG5 and ATG12 in vitiligo melanocytes. Deficiency of HSF1 led to accumulation of intracellular ROS, imbalance of mitochondrion membrane potential, and apoptosis in melanocytes exposure to oxidative stress. Furthermore, overexpression of HSF1 could ameliorate oxidative stress‒induced melanocytes death through the activation of autophagy by upregulating ATG5 and ATG12. These findings suggested that targeting HSF1-ATG5/12 axis could prevent oxidative stress‒induced melanocyte death and may be used as a therapeutic strategy for vitiligo treatment.

Protective Effect of Asiaticoside on Radiation-induced Proliferation Inhibition and DNA Damage of Fibroblasts and Mice Death

Background

Radiation-induced injuries (RII) mainly result from reactive oxygen species (ROS), which are harmful compounds that can damage DNA. Asiaticoside (AC), one of the main functional components extracted from Centella asiatica, has potent pharmacological effects such as anti-inflammatory and anti-oxidant activity. However, its role in RII remains unclear.

Purpose

The purpose of the current study is to investigate whether AC can mitigate RII in vitro and in vivo.

Material and Methods

Cell model of RII was successfully established by 5J/m₂ radiation in vitro. For the in vivo RII model, mice were irradiated with 5 Gy to the thorax. The degree of damage to cells or mouse tissue was determined by measuring the numbers of DNA double-strand breaks (DSBs), oxidative stress, and mouse survival rates.

Results

In the in vitro assay, AC administration significantly reduced radiation-induced growth inhibition of Escherichia coli and fibroblasts, DSBs and apoptosis of fibroblasts; in the in vivo study, AC could decrease antioxidant capacity (T-AOC) of plasma and protect mice from RII, thereby improving the survival rates of mice after radiation.

Conclusions

These novel data indicate that AC is able to prevent radiation-initiated genotoxicity by mitigating DNA damage, and might serve as a safe and effective radio-protective agent.

Ferrostatin-1 alleviates lipopolysaccharide-induced acute lung injury via inhibiting ferroptosis

Background

Ferroptosis is a newly recognized type of cell death, which is different from traditional necrosis, apoptosis or autophagic cell death. However, the position of ferroptosis in lipopolysaccharide (LPS)-induced acute lung injury (ALI) has not been explored intensively so far. In this study, we mainly analyzed the relationship between ferroptosis and LPS-induced ALI.

Methods

In this study, a human bronchial epithelial cell line, BEAS-2B, was treated with LPS and ferrostatin-1 (Fer-1, ferroptosis inhibitor). The cell viability was measured using CCK-8. Additionally, the levels of malondialdehyde (MDA), 4-hydroxynonenal (4-HNE), and iron, as well as the protein level of SLC7A11 and GPX4, were measured in different groups. To further confirm the in vitro results, an ALI model was induced by LPS in mice, and the therapeutic action of Fer-1 and ferroptosis level in lung tissues were evaluated.

Results

The cell viability of BEAS-2B was down-regulated by LPS treatment, together with the ferroptosis markers SLC7A11 and GPX4, while the levels of MDA, 4-HNE and total iron were increased by LPS treatment in a dose-dependent manner, which could be rescued by Fer-1. The results of the in vivo experiment also indicated that Fer-1 exerted therapeutic action against LPS-induced ALI, and down-regulated the ferroptosis level in lung tissues.

Conclusions

Our study indicated that ferroptosis has an important role in the progression of LPS-induced ALI, and ferroptosis may become a novel target in the treatment of ALI patients.

HMGB1 was negatively regulated by HSF1 and mediated the TLR4/MyD88/NF-κB signal pathway in asthma

AIMS

The present study explored the function and regulatory mechanism of High mobility group box 1 (HMGB1) in asthma.

MAIN METHODS

OVA (ovalbumin)-induced asthmatic mice model and LPS-treated cellular model were established in this study. Airway inflammation was measured through detecting the expression of IL-4, IL-5, IL-13 and Interferon-γ (IFN-γ) in serum and BALF (bronchoalveolar lavage fluid) by ELISA kits. Bioinformatics predictive analysis, ChIP assays, Luciferase reporter assay and Western blotting were used to explore the relation between HMGB1 and HSF1 (Heat shock factor 1).

KEY FINDINGS

HMGB1 expression was increased in OVA-induced asthmatic mice. Silencing HMGB1 attenuated the increasing of IgE, inflammatory factors (IL-4, IL-5 and IL-13), and airway hyperresponsiveness that induced by OVA. In addition, our study found that HSF1 directly bind with the HMGB1 promoter and negatively regulation of HMGB1. HSF-1 were upregulated in OVA-induced asthmatic mice, and knockdown of HSF1 aggravated the OVA-induced airway inflammation and airway hyperreactivity in mice may through promoting the expression of HMGB1 and the activation of the Toll-like receptor 4 (TLR4)/Myeloid differentiation primary response 88 (MyD88)/Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signal pathway.

SIGNIFICANCE

The expression of HMGB1 could be negatively regulated by HSF1, and the TLR4/MyD88/NF-κB signal pathway was involved in HSF1/HMGB1-mediated regulation of asthma.

Cardioprotective Effects of Puerarin-V on Isoproterenol-Induced Myocardial Infarction Mice Is Associated with Regulation of PPAR-Υ/NF-κB Pathway

Puerarin is a well-known traditional Chinese medicine which has been used for the treatment of cardiovascular diseases. Recently, a new advantageous crystal form of puerarin, puerarin-V, has been developed. However, the cardioprotective effects of puerarin-V on myocardial infarction (MI) heart failure are still unclear. In this research, we aim to evaluate the cardioprotective effects of puerarin-V on the isoproterenol (ISO)-induced MI mice and elucidate the underlying mechanisms. To induce MI in C57BL/6 mice, ISO was administered at 40 mg/kg subcutaneously every 12 h for three times in total. The mice were randomly divided into nine groups: (1) control; (2) ISO; (3) ISO + puerarin injection; (4⁻9) ISO + puerarin-V at different doses and timings. After treatment, cardiac function was evaluated by electrocardiogram (ECG), biochemical and histochemical analysis. In vitro inflammatory responses and apoptosis were evaluated in human coronary artery endothelial cells (HCAECs) challenged by lipopolysaccharide (LPS). LPS-induced PPAR-Υ/NF-κB and subsequently activation of cytokines were assessed by the western blot and real-time polymerase chain reaction (PCR). Administration of puerarin-V significantly inhibits the typical ST segment depression compared with that in MI mice. Further, puerarin-V treatment significantly improves ventricular wall infarction, decreases the incidence of mortality, and inhibits the levels of myocardial injury markers. Moreover, puerarin-V treatment reduces the inflammatory milieu in the heart of MI mice, thereby blocking the upregulation of proinflammatory cytokines (TNF-α, IL-1β and IL-6). The beneficial effects of puerarin-V might be associated with the normalization in gene expression of PPAR-Υ and PPAR-Υ/NF-κB /ΙκB-α/ΙΚΚα/β phosphorylation. In the in vitro experiment, treatment with puerarin-V (0.3, 1 and 3 μM) significantly reduces cell death and suppresses the inflammation cytokines expression. Likewise, puerarin-V exhibits similar mechanisms. The cardioprotective effects of puerarin-V treatment on MI mice in the pre + post-ISO group seem to be more prominent compared to those in the post-ISO group. Puerarin-V exerts cardioprotective effects against ISO-induced MI in mice, which may be related to the activation of PPAR-γ and the inhibition of NF-κB signaling in vivo and in vitro. Taken together, our research provides a new therapeutic option for the treatment of MI in clinic.