Nrf2 protects against acute lung injury and inflammation by modulating TLR4 and Akt signaling

TLR4 signalling in ischemia/reperfusion injury: a promising target for linking inflammation, oxidative stress and programmed cell death to improve organ transplantation outcomes

Transplantations represent the principal therapeutic interventions for terminal organ failure, a procedure that has salvaged myriad lives annually. Ischemia/reperfusion injury (IRI) is frequently correlated with an unfavourable prognosis and is relevant for early graft dysfunction and graft survival. IRI constitutes a complex pathological state influenced by a series of factors such as oxidative stress, metabolic stress, leukocytic infiltration, programmed cell death pathways, and inflammatory immune responses. Reducing ischemia/reperfusion injury is one of the main directions of transplantation research. Toll-like receptors (TLRs) are important pattern-recognition receptors expressed on various organs that orchestrate the immune responses upon recognising PAMPs and DAMPs. Targeting the TLR4 signalling has recently been suggested as a promising approach for alleviating IRI by affecting inflammation, oxidative stress and programmed cell death (PCD). In this minireview, we summarise the role of TLR4 signalling in regulating inflammation, oxidative stress and PCD in organ transplantation and discuss their interactions during IRI. A detailed understanding of the multiple functions of TLR4 in IRI provides novel insights into developing therapies to improve organ transplantation outcomes.

Targeting the AMPK/Nrf2 Pathway: A Novel Therapeutic Approach for Acute Lung Injury

ALI(acute lung injury) is a severe respiratory dysfunction caused by various intrapulmonary and extrapulmonary factors. It is primarily characterized by oxidative stress and affects the integrity of the pulmonary barrier. In severe cases, ALI can progress to ARDS(acute respiratory distress syndrome), a condition that poses a serious threat to the lives of affected patients. To date, the etiological mechanisms underlying ALI remain elusive, and available therapeutic options are quite limited. AMPK(AMP-activated protein kinase), an essential serine/threonine protein kinase, performs a pivotal function in the regulation of cellular energy levels and cellular regulatory mechanisms, including the detection of redox signals and mitigating oxidative stress. Meanwhile, Nrf2(nuclear factor erythroid 2-related factor 2), a critical transcription factor, alleviates inflammation and oxidative responses by interacting with multiple signaling pathways and contributing to the modulation of oxidative enzymes associated with inflammation and programmed cell death. Indeed, AMPK induces the dissociation of Nrf2 from Keap1(kelch-like ECH-associated protein-1) and facilitates its translocation into the nucleus to trigger the transcription of downstream antioxidant genes, ultimately suppressing the expression of inflammatory cells in the lungs. Given their roles, AMPK and Nrf2 hold promise as novel treatment targets for ALI. This study aimed to summarise the current status of research on the AMPK/Nrf2 signaling pathway in ALI, encompassing recently reported natural compounds and drugs that can activate the AMPK/Nrf2 signaling pathway to alleviate lung injury, and provide a theoretical reference for early intervention in lung injury and future research on lung protection.

Advancements in the study of acute lung injury resulting from intestinal ischemia/reperfusion

Intestinal ischemia/reperfusion is a prevalent pathological process that can result in intestinal dysfunction, bacterial translocation, energy metabolism disturbances, and subsequent harm to distal tissues and organs via the circulatory system. Acute lung injury frequently arises as a complication of intestinal ischemia/reperfusion, exhibiting early onset and a grim prognosis. Without appropriate preventative measures and efficacious interventions, this condition may progress to acute respiratory distress syndrome and elevate mortality rates. Nonetheless, the precise mechanisms and efficacious treatments remain elusive. This paper synthesizes recent research models and pertinent injury evaluation criteria within the realm of acute lung injury induced by intestinal ischemia/reperfusion. The objective is to investigate the roles of pathophysiological mechanisms like oxidative stress, inflammatory response, apoptosis, ferroptosis, and pyroptosis; and to assess the strengths and limitations of current therapeutic approaches for acute lung injury stemming from intestinal ischemia/reperfusion. The goal is to elucidate potential targets for enhancing recovery rates, identify suitable treatment modalities, and offer insights for translating fundamental research into clinical applications.

Protective effect of Xixin-Ganjiang herb pair for warming the lungs to dissolve phlegm in chronic obstructive pulmonary disease rats based on integrated network pharmacology and metabolomics

Xixin-Ganjiang herb pair (XGHP) is a classic combination for warming the lungs to dissolve phlegm and is often used to treat a variety of chronic lung diseases; it can treat the syndrome of cold phlegm obstruction of lungs. First, ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used to examine the composition of XGHP, and network pharmacology was used to predict its potential core targets and signaling pathways in the current study. Second, a rat model of chronic obstructive pulmonary disease (COPD) was established for assessing the anti-COPD activity of XGHP, and metabolomics was used to explore the biomarkers and metabolic pathways. Finally, the sample was validated using molecular docking and Western blotting. The integration of metabolomics and network pharmacology results identified 11 targets, 3 biomarkers, 3 pathways, and 2 metabolic pathways. Western blotting showed that XGHP effectively regulated the expression of core proteins via multiple signaling pathways (downregulation of toll-like receptor 4 [TLR4] and upregulation of serine/threonine-protein kinase 1 [p-AKT1] and nitric oxide synthase 3 [NOS3]). Molecular docking results showed that the 10 potentially active components of XGHP have good affinity with tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), matrix metalloproteinase 9 (MMP-9), TLR4, p-AKT1, and NOS3. Our findings suggest that XGHP may regulate glucolipid metabolism, improve energy supply, and inhibit inflammatory responses (TNF-α, IL-6, and MMP-9) via the PI3K-Akt signaling pathway and HIF-1 signaling pathway in the management of COPD.

Therapeutic potential of proteases in acute lung injury and respiratory distress syndrome via TLR4/Nrf2/NF-kB signaling modulation

The COVID-19 pandemic has drawn attention to acute lung injury and respiratory distress syndrome as major causes of death, underscoring the urgent need for effective treatments. Protease enzymes possess a wide range of beneficial effects, including antioxidant, anti-inflammatory, antifibrotic, and fibrinolytic effects. This study aimed to evaluate the potential therapeutic effects of bacterial protease and chymotrypsin in rats in mitigating acute lung injury induced by lipopolysaccharide. Molecular docking was employed to investigate the inhibitory effect of bacterial protease and chymotrypsin on TLR-4, the receptor for lipopolysaccharide. Bacterial protease restored TLR-4, Nrf2, p38 MAPK, NF-kB, and IKK-β levels to normal levels, while chymotrypsin normalized TLR-4, IKK-β, IL-6, and IL-17 levels. The expression of TGF-β, caspase-3, and VEGF in the bacterial protease- and chymotrypsin-treated groups was markedly reduced. Our results suggest that both therapies ameliorate LPS-induced acute lung injury and modulate the TLR4/Nrf2/NF-k signaling pathway. Each protease exhibited distinct mechanisms, with bacterial protease showing a better response to oxidative stress, edema, and fibrosis, whereas chymotrypsin provided a better response in the acute phase and innate immunity. These findings highlight the potential of each protease as a promising therapeutic option for acute lung injury and respiratory distress syndrome.

Protective effects of sodium humate and its zinc and selenium chelate on the oxidative stress, inflammatory, and intestinal barrier damage of Salmonella Typhimurium-challenged broiler chickens

The objective of this study was to investigate the protective effects and mechanisms of dietary administration of sodium humate (HNa) and its zinc and selenium chelate (Zn/Se-HNa) in mitigating Salmonella Typhimurium (S. Typhi) induced intestinal injury in broiler chickens. Following the gavage of 109 CFU S. Typhi to 240 broilers from 21-d to 23-d aged, various growth performance parameters such as body weight (BW), average daily gain (ADG), average daily feed intake (ADFI), and feed ratio (FCR) were measured before and after infection. Intestinal morphology was assessed to determine the villus height, crypt depth, and chorionic cryptologic ratio. To evaluate intestinal barrier integrity, levels of serum diamine oxidase (DAO), D-lactic acid, tight junction proteins, and the related genes were measured in each group of broilers. An analysis was conducted on inflammatory-related cytokines, oxidase activity, and Nuclear Factor Kappa B (NF-κB) and Nuclear factor erythroid2-related factor 2 (Nrf2) pathway-related proteins and mRNA expression. The results revealed a significant decrease in BW, ADG, and FCR in S. typhi-infected broilers. HNa tended to increase FCR (P = 0.056) while the supplementation of Zn/Se-HNa significantly restored BW and ADG (P < 0.05). HNa and Zn/Se-HNa exhibit favorable and comparable effects in enhancing the levels of serum DAO, D-lactate, and mRNA and protein expression of jejunum and ileal tight junction. In comparison to HNa, Zn/Se-HNa demonstrates a greater reduction in S. Typhi shedding in feces, as well as superior efficacy in enhancing the intestinal morphology, increasing serum catalase (CAT) activity, inhibiting pro-inflammatory cytokines, and suppressing the activation of the NF-κB pathway. Collectively, Zn/Se-HNa was a more effective treatment than HNa to alleviate adverse impact of S. Typhi infection in broiler chickens.

Crtc1 deficiency protects against sepsis-associated acute lung injury through activating akt signaling pathway

BACKGROUND

Interplay between systemic inflammation and programmed cell death contributes to the pathogenesis of acute lung injury (ALI). cAMP-regulated transcriptional coactivator 1 (CRTC1) has been involved in the normal function of the pulmonary system, but its role in ALI remains unclear.

METHODS AND RESULTS

We generated a Crtc1 knockout (KO; Crtc1-/-) mouse line. Sepsis-induced ALI was established by cecal ligation and puncture (CLP) for 24 h. The data showed that Ctrc1 KO substantially ameliorated CLP-induced ALI phenotypes, including improved lung structure destruction, reduced pulmonary vascular permeability, diminished levels of proinflammatory cytokines and chemokines, compared with the wildtype mice. Consistently, in lipopolysaccharide (LPS)-treated RAW264.7 cells, Crtc1 knockdown significantly inhibited the expression of inflammatory effectors, including TNF-α, IL-1β, IL-6 and CXCL1, whereas their expressions were significantly enhanced by Crtc1 overexpression. Moreover, both Crtc1 KO in mice and its knockdown in RAW264.7 cells dramatically reduced TUNEL-positive cells and the expression of pro-apoptotic proteins. In contrast, Crtc1 overexpression led to an increase in the pro-apoptotic proteins and LPS-induced TUNEL-positive cells. Mechanically, we found that the phosphorylation of Akt was significantly enhanced by Crtc1 knockout or knockdown, but suppressed by Crtc1 overexpression. Administration of Triciribine, an Akt inhibitor, substantially blocked the protection of Crtc1 knockdown on LPS-induced inflammation and cell death in RAW264.7 cells.

CONCLUSIONS

Our study demonstrates that CRTC1 contribute to the pathological processes of inflammation and apoptosis in sepsis-induced ALI, and provides mechanistic insights into the molecular function of CRTC1 in the lung. Targeting CRTC1 would be a promising strategy to treat sepsis-induced ALI in clinic.

Nrf2 activation: a key mechanism in stem cell exosomes-mediated therapies

Exosomes are nano-sized membrane extracellular vesicles which can be released from various types of cells. Exosomes originating from inflammatory or injured cells can have detrimental effects on recipient cells, while exosomes derived from stem cells not only facilitate the repair and regeneration of damaged tissues but also inhibit inflammation and provide protective effects against various diseases, suggesting they may serve as an alternative strategy of stem cells transplantation. Exosomes have a fundamental role in communication between cells, through the transfer of proteins, bioactive lipids and nucleic acids (like miRNAs and mRNAs) between cells. This transfer significantly impacts both the physiological and pathological functions of recipient cells. Nuclear factor erythroid 2-related factor 2 (Nrf2), a transcription factor, is able to mitigate damage caused by oxidative stress and inflammation through various signaling pathways. The positive effects resulting from the activation of the Nrf2 signaling pathway in different disorders have been documented in various types of literature. Studies have confirmed that exosomes derived from stem cells could act as Nrf2 effective agonists. However, limited studies have explored the Nrf2 role in the therapeutic effects of stem cell-derived exosomes. This review provides a comprehensive overview of the existing knowledge concerning the role of Nrf2 signaling pathways in the impact exerted by stem cell exosomes in some common diseases.

Hydrogen exerts neuroprotective effects after subarachnoid hemorrhage by attenuating neuronal ferroptosis and inhibiting neuroinflammation

OBJECTIVE

Spontaneous subarachnoid hemorrhage (SAH), the third most common stroke subtype, is associated with high mortality and disability rates. Therefore, finding effective therapies to improve neurological function after SAH is critical. The objective of this study was to investigate the potential neuroprotective effects of hydrogen in the context of SAH, specifically, by examining its role in attenuating neuronal ferroptosis and inhibiting neuroinflammation, which are exacerbated by excess iron ions after SAH.

METHODS

Mice were exposed to chambers containing 3% hydrogen, and cells were cultured in incubators containing 60% hydrogen. Neurological function in mice was assessed using behavioral scores. Protein changes were detected using western blotting. Inflammatory factors were detected using enzyme linked immunosorbent assay. Probes, electron microscopy, and related kits were employed to detect oxidative stress and ferroptosis.

RESULTS

Hydrogen improved the motor function, sensory function, and cognitive ability of mice after SAH. Additionally, hydrogen facilitated Nuclear factor erythroid 2 -related factor 2 activation, upregulated Glutathione peroxidase 4, and inhibited Toll-like receptor 4, resulting in downregulation of inflammatory responses, attenuation of oxidative stress after SAH, and inhibition of neuronal ferroptosis.

CONCLUSION

Hydrogen exerts neuroprotective effects by inhibiting neuronal ferroptosis and attenuating neuroinflammation after SAH.

The possible role of nuclear factor erythroid-2-related factor 2 activators in the management of Covid-19

COVID-19 is caused by a novel SARS-CoV-2 leading to pulmonary and extra-pulmonary manifestations due to oxidative stress (OS) development and hyperinflammation. COVID-19 is primarily asymptomatic though it may cause acute lung injury (ALI), acute respiratory distress syndrome (ARDS), systemic inflammation, and thrombotic events in severe cases. SARS-CoV-2-induced OS triggers the activation of different signaling pathways, which counterbalances this complication. One of these pathways is nuclear factor erythroid 2-related factor 2 (Nrf2), which induces a series of cellular interactions to mitigate SARS-CoV-2-mediated viral toxicity and OS-induced cellular injury. Nrf2 pathway inhibits the expression of pro-inflammatory cytokines and the development of cytokine storm in COVID-19. Therefore, Nrf2 activators may play an essential role in reducing SARS-CoV-2 infection-induced inflammation by suppressing NLRP3 inflammasome in COVID-19. Furthermore, Nrf2 activators can attenuate endothelial dysfunction (ED), renin-angiotensin system (RAS) dysregulation, immune thrombosis, and coagulopathy. Thus this mini-review tries to clarify the possible role of the Nrf2 activators in the management of COVID-19. Nrf2 activators could be an effective therapeutic strategy in the management of Covid-19. Preclinical and clinical studies are recommended in this regard.

Nardostachys jatamansi and levodopa combination alleviates Parkinson's disease symptoms in rats through activation of Nrf2 and inhibition of NLRP3 signaling pathways

CONTEXT

Levodopa combined with traditional Chinese medicine has a synergistic effect on Parkinson's disease (PD). Recently, we demonstrated that Nardostachys jatamansi (D. Don) DC. [syn. Patrinia jatamansi D.Don, N. grandiflora DC.] (Valerianaceae) (NJ) can alleviate PD.

OBJECTIVE

To explore the synergistic effect of NJ combined with levodopa against PD.

MATERIALS AND METHODS

The PD model was established by injecting rotenone. Eighty-four Sprague-Dawley rats were randomly divided into seven groups: sham, model, different doses of NJ (0.31, 0.62, or 1.24 g/kg) combined with levodopa (25 mg/kg), and levodopa alone (25 and 50 mg/kg) groups. The synergistic effect of the combination was investigated by pharmacodynamic investigation and detection of expression of nuclear factor erythro2-related factor 2 (Nrf2) and NLR family proteins containing Pyrin-related domain 3 (NLRP3) pathways.

RESULTS

Compared with the model group, NJ + levodopa (1.24 g/kg + 25 mg/kg) increased the moving distance of PD rats in the open field (2395.34 ± 668.73 vs. 1501.41 ± 870.23, p < 0.01), enhanced the stay time on the rotating rod (84.86 ± 18.15 vs. 71.36 ± 17.53, p < 0.01) and the combination was superior to other treatments. The synergistic effects were related to NJ + levodopa (1.24 g/kg + 25 mg/kg) increasing the neurotransmitter levels by 38.80%-88.67% in PD rats, and inhibiting oxidative stress and NLRP3 pathway by activating Nrf2 pathway.

DISCUSSION AND CONCLUSIONS

NJ combined with levodopa is a promising therapeutic candidate for PD, which provides a scientific basis for the subsequent clinical combination therapy of levodopa to enhance the anti-PD effect.

Protective effect of canagliflozin on post-resuscitation myocardial function in a rat model of cardiac arrest

BACKGROUND

Currently, most patients with cardiac arrest (CA) show reversible myocardial dysfunction, hemodynamic instability, systemic inflammation and other pathophysiological state in early stage of resuscitation, some patients may eventually progress to multiple organ failure. There is evidence that heart failure is the terminal stage in the development of various cardiovascular diseases. Although the cardio-protective effect of canagliflozin (CANA) has been confirmed in large clinical studies and recommended in domestic and international heart failure-related guidelines, the effectiveness of CANA after resuscitation remains unclear. In this study, we constructed a modified CA/CPR rat model to investigate whether CANA administered on post-resuscitation improves myocardial function.

METHODS

Twenty-fourth healthy male Sprague-Dawley rats were randomized into four groups: (1) Sham + placebo group, (2) Sham + CANA group, (3) CPR + placebo group, and (4) CPR + CANA group. Ventricular fibrillation was induced by transcutaneous electrical stimulation on epicardium. After 6 min untreated ventricular fibrillation, chest compressions was initiated. The rats were received an injection of placebo or canagliflozin (3 ug/kg) randomly 15 min after restore of spontaneous circulation (ROSC). Electrocardiogram (ECG) and blood pressure were continuously detected in each group throughout the experiment. The rats were killed 6 h after ROSC to collected the arterial serum and myocardial tissue. Myocardial injury was estimated with concentrations of inflammatory factors, oxidative stress indexes and, apoptosis index, myocardial injury markers, echocardiography and myocardial pathological slices.

RESULTS

After resuscitation, mean arterial pressure (MAP) were significantly increased after cardiopulmonary resuscitation in CANA group rats when compared with placebo group. Heart rate, body lactate returned and left ventricular ejection fraction (LVEF) to normal levels in a shorter time and the myocardial injury was obviously attenuated in CPR + CANA group. Inflammatory factors (IL-6, TNF-α) and oxidative stress indexes (MAD, SOD, CAT) were dramatically decreased with the administration of CANA. The expression of apoptosis index (BAX, caspase-3) were higher in CPR + placebo group and the expression of anti-apoptosis index (Bcl-2) was lower (P < 0.05).

CONCLUSIONS

The administration of CANA effectively reduces myocardial ischaemia/reperfusion (I/R) injury after cardiac arrest and cardiopulmonary resuscitation (CPR), and the underlying mechanism may be related to anti-inflammation, oxidative stress and apoptosis.

Study on the Alleviating Effect and Potential Mechanism of Ethanolic Extract of Limonium aureum (L.) Hill. on Lipopolysaccharide-Induced Inflammatory Responses in Macrophages

Inflammation is the host response of immune cells during infection and traumatic tissue injury. An uncontrolled inflammatory response leads to inflammatory cascade, which in turn triggers a variety of diseases threatening human and animal health. The use of existing inflammatory therapeutic drugs is constrained by their high cost and susceptibility to systemic side effects, and therefore new therapeutic candidates for inflammatory diseases need to be urgently developed. Natural products are characterized by wide sources and rich pharmacological activities, which are valuable resources for the development of new drugs. This study aimed to uncover the alleviating effect and potential mechanism of natural product Limonium aureum (LAH) on LPS-induced inflammatory responses in macrophages. The experimental results showed that the optimized conditions for LAH ultrasound-assisted extraction via response surface methodology were an ethanol concentration of 72%, a material-to-solvent ratio of 1:37 g/mL, an extraction temperature of 73 °C, and an extraction power of 70 W, and the average extraction rate of LAH total flavonoids was 0.3776%. Then, data of 1666 components in LAH ethanol extracts were obtained through quasi-targeted metabolomics analysis. The ELISA showed that LAH significantly inhibited the production of pro-inflammatory cytokines while promoting the secretion of anti-inflammatory cytokines. Finally, combined with the results of network pharmacology analysis and protein expression validation of hub genes, it was speculated that LAH may alleviate LPS-induced inflammatory responses of macrophages through the AKT1/RELA/PTGS2 signaling pathway and the MAPK3/JUN signaling pathway. This study preliminarily revealed the anti-inflammatory activity of LAH and the molecular mechanism of its anti-inflammatory action, and provided a theoretical basis for the development of LAH as a new natural anti-inflammatory drug.

SARS-CoV-2 infection and dysregulation of nuclear factor erythroid-2-related factor 2 (Nrf2) pathway

Coronavirus disease 2019 (COVID-19) is a recent pandemic caused by a novel severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) leading to pulmonary and extra-pulmonary manifestations due to the development of oxidative stress (OS) and hyperinflammation. The underlying cause for OS and hyperinflammation in COVID-19 may be related to the inhibition of nuclear factor erythroid 2-related factor 2 (Nrf2), a master regulator of antioxidative responses and cellular homeostasis. The Nrf2 pathway inhibits the expression of pro-inflammatory cytokines and the development of cytokine storm and OS in COVID-19. Nrf2 activators can attenuate endothelial dysfunction (ED), renin-angiotensin system (RAS) dysregulation, immune thrombosis, and coagulopathy. Hence, this review aimed to reveal the potential role of the Nrf2 pathway and its activators in the management of COVID-19. As well, we tried to revise the mechanistic role of the Nrf2 pathway in COVID-19.

HMGB1 inhibition reduces TDI-induced occupational asthma through ROS/AMPK/autophagy pathway

Exposure to toluene diisocyanate (TDI) can cause pulmonary diseases such as asthma. Inhibition of high mobility group box 1 protein (HMGB1) has been found to be protective against the toxic effects of TDI on human bronchial epithelial (HBE) cells. Here, we evaluated the in vivo positive roles of HMGB1 in the TDI-caused asthma mice and explored its underlying mechanisms in HBE cells. We found that suppression of HMGB1 obviously alleviated airway inflammation, airway hyperresponsiveness, and airway remodeling in the lung tissue of the asthma mice. The in vitro results showed that inhibition of HMGB1 ameliorated TDI-induced reactive oxygen species (ROS) release, inflammatory response, and activation of autophagy in HBE cells. At the molecular level, inhibition of HMGB1 decreased the expressions of HMGB1, Toll-like receptor 4, Vimentin and matrix metalloproteinase-9 proteins, activated NF-κB and NOD-like receptor protein 3 (NLRP3) inflammasome, and increased E-cadherin expression. Importantly, activation of autophagy could lead to the overactivation of NLRP3 inflammasome in TDI-induced asthma. These results suggest that inhibition of HMGB1 can alleviate TDI-induced asthma through ROS/AMPK/autophagy pathways, which may provide valuable evidence for the pathogenesis and therapeutic targets of TDI-induced asthma.

Lactobacillus reuteri Ameliorates Lipopolysaccharide-Induced Acute Lung Injury by Modulating the Gut Microbiota in Mice

Acute lung injury (ALI) causes lung inflammation and edema as well as resulting in gut microbiota disorder. Probiotics, however, can improve the gut microbiota composition and modulate its immune response, playing an important role in ALI pathogenesis. Therefore, our study aims to investigate the effect of Lactobacillus reuteri on Lipopolysaccharide (LPS)-induced ALI in mice and to probe the mechanism of its synergistic modulatory effect on the lungs and intestines. We assessed the therapeutic effects of L. reuteri in the ALI mouse model by histopathology, alveolar lavage fluid and serum inflammatory factor analysis and explored microbiome and transcriptome alterations. L. reuteri intervention effectively attenuated lung tissue injury and significantly reduced the LPS-induced inflammatory response and macrophage and neutrophil infiltration. Additionally, L. reuteri improved the intestinal barrier function and remodeled the disordered microbiota. In conclusion, our study showed that L. reuteri attenuated the inflammatory response, ameliorated the pulmonary edema, repaired the intestinal barrier, and remodeled the gut microbiota in ALI mice. This study provides new perspectives on the clinical treatment of ALI.

Role and mechanism of ferroptosis in acute lung injury

Ferroptosis is a new non-apoptotic cell death caused by the accumulation of dysregulated metabolism of ferric iron, amino acids or lipid peroxidation. Increasing studies suggest that ferroptosis is involved in the acute lung injury (ALI). This article aims to review the role of ferroptosis in ALI. ALI is a common respiratory disease and presents a high mortality rate. Inhibiting cell ferroptosis of lung improves the ALI. In addition, several signaling pathways are related to ferroptosis in ALI, involving in iron homeostasis, lipid peroxidation, and amino acid metabolism. Moreover, there are various key factors to regulate the occurrence of ferroptosis in ALI, such as ACSL4, NRF2, and P53. The ACSL4 promotes the ferroptosis, while the NRF2 alleviates the ferroptosis in ALI. The main effect of P53 is to promote ferroptosis. Accordingly, ferroptosis is involved in ALI and may be an important therapeutic target for ALI.

Oxidative Stress as a Regulatory Checkpoint in the Production of Antiphospholipid Autoantibodies: The Protective Role of NRF2 Pathway

Oxidative stress is a well-known hallmark of Antiphospholipid Antibody Syndrome (APS), a systemic autoimmune disease characterized by arterial and venous thrombosis and/or pregnancy morbidity. Oxidative stress may affect various signaling pathways and biological processes, promoting dysfunctional immune responses and inflammation, inducing apoptosis, deregulating autophagy and impairing mitochondrial function. The chronic oxidative stress and the dysregulation of the immune system leads to the loss of tolerance, which drives autoantibody production and inflammation with the development of endothelial dysfunction. In particular, anti-phospholipid antibodies (aPL), which target phospholipids and/or phospholipid binding proteins, mainly β-glycoprotein I (β-GPI), play a functional role in the cell signal transduction pathway(s), thus contributing to oxidative stress and thrombotic events. An oxidation-antioxidant imbalance may be detected in the blood of patients with APS as a reflection of disease progression. This review focuses on functional evidence highlighting the role of oxidative stress in the initiation and progression of APS. The protective role of food supplements and Nuclear Factor Erythroid 2-Related Factor 2 (NRF2) activators in APS patients will be summarized to point out the potential of these therapeutic approaches to reduce APS-related clinical complications.

Sex-specific association of exposure to air pollutants and Nrf2 gene expression and inflammatory biomarkers in exhaled breath of healthy adolescents

Studies investigating the nuclear factor erythroid 2-related factor 2 (Nrf2) expression levels in the respiratory system of healthy subjects are scarce. Moreover, separate studies on the health-related outcomes of air pollution for each sex are limited. The current panel study investigated sex-specific Nrf2 expression levels and related oxidative stress and inflammatory responses among healthy adolescents exposed to PM2.5, PM10, O3, and PM2.5-bounded metals in a high traffic region. Forty-nine healthy nonsmoking subjects participated in the study for five consecutive months (Nov. 2019 to Feb. 2020). Each subject was asked to provide 1 mL of exhaled breath condensate (EBC). Data were analyzed using linear mixed-effects models. The results showed that PM10, PM2.5, O3, and PM2.5-bounded metals were negatively linked to Nrf2 expression level in EBC of females with -58.3% (95% CI: 79.5, -15.4), -32.1% (95% CI: -50.3, -7.1), -76.2% (95% CI: -92.6, -23.9), and -1.9 (95% CI: -3.4, -0.4), respectively. While our results presented no significant association between the studied pollutants and Nrf2 gene expression in males, significant associations were observed between the pollutants and total nitric oxide (NOx), interleukins 6 (IL-6), and tumor necrosis factor-alpha (TNF-α) in the EBC of females. In the case of males, only EBC cytokines showed a significant association with air pollutants. Overall, this study suggests that exposure to ambient air pollutants may affect the respiratory system with biologically different mechanisms in males and females. PM2.5 concentration had a positive correlation with exhaled TNF-α and IL6 values in females while positive correlation with TNF-α and negative correlation with IL6 values in males. O3 had a negative correlation with TNF-α in males.

Sulforaphane alleviates lung ischemia‑reperfusion injury through activating Nrf‑2/HO‑1 signaling

Oxidative stress and inflammation are both involved in the pathogenesis of lung ischemia-reperfusion (I/R) injury. Sulforaphane (SFN) is a natural product with cytoprotective, anti-inflammatory, and antioxidant properties. The present study hypothesized that SFN may protect against lung I/R injury via the regulation of antioxidant and anti-inflammatory-related pathways. A rat model of lung I/R injury was established, and rats were randomly divided into 3 groups: Sham group, I/R group, and SFN group. It was shown that SFN protected against a pathological inflammatory response via inhibition of neutrophil accumulation and in the reduction of the serum levels of the pro-inflammatory cytokines, IL-6, IL-1β, and TNF-α. SFN treatment also significantly inhibited lung reactive oxygen species production, decreased the levels of 8-OH-dG and malondialdehyde, and reversed the decrease in the antioxidant activities of the enzymes catalase, superoxide dismutase, and glutathione peroxidase in the lungs of the I/R treated rats. In addition, SFN ameliorated I/R-induced lung apoptosis in rats by suppressing Bax and cleaved caspase-3 levels and increased Bcl-2 expression. Furthermore, SFN treatment activated an Nrf2-related antioxidant pathway, as indicated by the increased nuclear transfer of Nrf2 and the downstream HO-1 and NADPH quinone oxidoreductase-1. In conclusion, these findings suggested that SFN protected against I/R-induced lung lesions in rats via activation of the Nrf2/HO-1 pathway and the accompanied anti-inflammatory and anti-apoptotic effects.

Dopamine D1 receptor agonist alleviates acute lung injury via modulating inflammatory responses in macrophages and barrier function in airway epithelial cells

Acute lung injury (ALI) or its severe form, acute respiratory distress syndrome (ARDS) is a life-threatening illness without effective therapeutic interventions currently. Multiple lines of evidence indicated that overwhelming inflammatory responses and impaired epithelial barrier contributed to the pathogenesis of ALI/ARDS. Recently, dopamine (DA) system was identified to participate in various pulmonary diseases. Here, we discovered that dopamine D1-like receptors mainly expressed in macrophages and airway epithelial cells (AECs), which were downregulated by lipopolysaccharide (LPS) challenge in ALI mouse lung. SKF38393 (SKF) is a selective agonist for D1-like receptors and was demonstrated to inhibit excessive inflammatory responses and oxidative stress in THP-1 cell-derived macrophages and Beas-2B cells, as well as improve airway epithelial barrier dysfunction induced by LPS stimulation. Moreover, SKF administration could effectively decrease pulmonary inflammation, ameliorate tissue damage in the LPS-triggered ALI mice. The broad protective actions of SKF might be attributed to the activation of Nrf2 antioxidative system by use of the specific inhibitor, ML385. This study offers evidence of potent immunoregulatory activity of SKF in macrophages, AECs as well as ALI mouse model, which opens novel therapeutic avenues for the intervention of ALI/ARDS.

Impact of chronic cold exposure on lung inflammation, pyroptosis and oxidative stress in mice

Chronic cold exposure, which is the main inducer of lung diseases in high latitudes, affects production efficiency and restricts the development of aquaculture. Although the relationship between cold exposure and susceptibility to the lungs is widely accepted, but the influence between them has not been fully explored. The aim of this study is to understand the underlying mechanism. In the present study, the mice, which are used to establish cold stress (CS)-induced lung injury model, are exposed to cold temperature (4 °C) for 3 h each day for 4 weeks. The results indicate that the expression of heat shock protein 70 (HSP70) is augmented by cold exposure. In addition, chronic cold exposure aggravate the formation of malondialdehyde (MDA) and lead to a significant decrease in the contents of micrococcus catalase (CAT) and glutathione (GSH). Moreover, chronic cold exposure significantly exacerbates the expression of inflammation- and apoptosis-related proteins. The activation of Bax and caspase-3 are significantly augmented. However, that of Bcl-2 is decreased. These results are different from those in room team. The results show that chronic cold exposure plays an important roles in the activation of multiple signaling pathways, such as pyroptosis-related, inflammation-related and oxidative stress-regulated signaling pathways. In summary, these investigations support that chronic cold exposure increase the risk of lung injury by activating inflammation, oxidative stress and pyroptosis.

Molecular mechanisms of cell death in bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) in neonates is the most common pulmonary disease that causes neonatal mortality, has complex pathogenesis, and lacks effective treatment. It is associated with chronic obstructive pulmonary disease, pulmonary hypertension, and right ventricular hypertrophy. The occurrence and development of BPD involve various factors, of which premature birth is the most crucial reason for BPD. Under the premise of abnormal lung structure and functional product, newborns are susceptible to damage to oxides, free radicals, hypoxia, infections and so on. The most influential is oxidative stress, which induces cell death in different ways when the oxidative stress balance in the body is disrupted. Increasing evidence has shown that programmed cell death (PCD), including apoptosis, necrosis, autophagy, and ferroptosis, plays a significant role in the molecular and biological mechanisms of BPD and the further development of the disease. Understanding the mode of PCD and its signaling pathways can provide new therapeutic approaches and targets for the clinical treatment of BPD. This review elucidates the mechanism of BPD, focusing on the multiple types of PCD in BPD and their molecular mechanisms, which are mainly based on experimental results obtained in rodents.

Exosomes from Adipose-Derived Stem Cells Alleviate Dexamethasone-Induced Bone Loss by Regulating the Nrf2/HO-1 Axis

The widespread use of therapeutic glucocorticoids has increased the incidences of glucocorticoid-induced osteoporosis (GIOP). Oxidative stress and mitochondrial dysfunction are major causes of GIOP; therefore, alleviation of excess oxidative stress in osteoblasts is a potential therapeutic strategy for osteoporosis. Exosomes derived from ADSCs (ADSCs-Exos), as novel cell-free therapeutics, can modulate various biological processes, such as immunomodulation, reduce oxidative damage, and promote tissue repair as well as regeneration. In this study, ADSCs-Exos restored the viability and osteogenic potential of MC3T3-E1 cells by attenuating apoptosis, oxidative damage, intracellular ROS generation, and mitochondrial dysfunction. Moreover, after pretreatment with ADSCs-Exos, Nrf2 expressions were upregulated in Dex-stimulated osteoblasts. Inhibitory assays showed that silencing Nrf2 partially eliminated the protective effects of ADSCs-Exos. The rat model assays confirmed that ADSCs-Exos alleviated the Dex-induced increase in oxidation levels, restored bone mass of the distal femur, and increased the expressions of Nrf2 and osteogenic markers in bone tissues. Thus, ADSCs-Exos alleviated apoptosis and oxidative stress by regulating Nrf2/HO-1 expressions after Dex and prevented the development of GIOP in vivo.

Nrf2 regulates the expression of NOX1 in TNF-α-induced A549 cells

Acute lung injury causes severe inflammation and oxidative stress in lung tissues. In this study, we analyzed the potential regulatory role of nuclear factor erythroid-2-related factor 2 (Nrf2) on NADPH oxidase 1 (NOX1) in tumor necrosis factor-α (TNF-α)-induced inflammation and oxidative stress in human type II alveolar epithelial cells. In this study, A549 cells were transfected with Nrf2 siRNA and overexpression vectors for 6 h before being induced by TNF-α for 24 h. TNF-α upregulated the expression of NOX1 and Nrf2 in A549 cells. Furthermore, overexpression of Nrf2 could reduce TNF-α-induced NF-κB mRNA and protein expression after transfection with the Nrf2 siRNA vector, and the levels of IL-6, IL-8, ROS, and malondialdehyde (MDA) in TNF-α-induced A549 cells increased, while the level of total antioxidation capability (T-AOC) decreased. On the other hand, the overexpression of Nrf2 decreased the levels of IL-6, IL-8, ROS, and MDA, while increasing T-AOC. The mRNA and protein levels of NOX1 were dramatically increased by TNF-α, while those changes were notably suppressed by Nrf2 overexpression. Further studies demonstrated that Nrf2 suppressed NOX1 transcription by binding to the -1199 to -1189 bp (ATTACACAGCA) region of the NOX1 promoter in TNF-α-stimulated A549 cells. Our study suggests that Nrf2 may bind to and regulate NOX1 expression to antagonize TNF-α-induced inflammatory reaction and oxidative stress in A549 cells.

Nrf2 Deficiency Exacerbated CLP-Induced Pulmonary Injury and Inflammation through Autophagy- and NF-κB/PPARγ-Mediated Macrophage Polarization

The balance between M1 and M2 macrophage polarization is involved in the regulation of pulmonary inflammation. Nuclear factor erythroid-derived 2-like 2 (Nfe2l2, also known as Nrf2), a nuclear transcription factor, is reported to play protective roles in acute lung injury (ALI) and inflammation, and increasing evidence indicates that the protective effects of Nrf2 are closely related to autophagy. This study aimed to explore whether Nrf2 is involved in sepsis-induced acute pulmonary injury and inflammation and in the role of macrophage polarization in the process. In the present study, sepsis patients, an Nrf2 knockout mouse that underwent cecal ligation and puncture (CLP), and lipopolysaccharide (LPS)-treated macrophage cell lines were employed to investigate the potential functions of Nrf2 in sepsis-induced lung injury and the underlying mechanisms. Clinical studies showed that the NRF2 mRNA level was inversely correlated with pulmonary inflammation and disease severity in patients with sepsis. Analyses in a CLP-treated Nrf2 knockout mouse model indicated that an Nrf2 deficiency promoted a CLP-induced increase in M1 macrophage polarization and apoptosis and inhibited CLP-induced upregulation of the autophagy level in lung tissues. Experiments in RAW264.7 cells revealed that Nrf2 overexpression inhibited M1 macrophage polarization but promoted M2 macrophage polarization by improving the autophagy, and Nrf2 overexpression promoted PPARγ but inhibited NF-κB nuclear translocation. In conclusion, these results indicate that Nrf2 plays a protective role in sepsis-induced pulmonary injury and inflammation through the regulation of autophagy- and NF-κB/PPARγ-mediated macrophage polarization.

The protective effect of natural medicines against excessive inflammation and oxidative stress in acute lung injury by regulating the Nrf2 signaling pathway

Acute lung injury (ALI) is a common critical disease of the respiratory system that progresses into acute respiratory distress syndrome (ARDS), with high mortality, mainly related to pulmonary oxidative stress imbalance and severe inflammation. However, there are no clear and effective treatment strategies at present. Nuclear factor erythroid 2-related factor 2(Nrf2) is a transcription factor that interacts with multiple signaling pathways and regulates the activity of multiple oxidases (NOX, NOS, XO, CYP) related to inflammation and apoptosis, and exhibits antioxidant and anti-inflammatory roles in ALI. Recently, several studies have reported that the active ingredients of natural medicines show protective effects on ALI via the Nrf2 signaling pathway. In addition, they are cheap, naturally available, and possess minimal toxicity, thereby having good clinical research and application value. Herein, we summarized various studies on the protective effects of natural pharmaceutical components such as polyphenols, flavonoids, terpenoids, alkaloids, and polysaccharides on ALI through the Nrf2 signaling pathway and demonstrated existing gaps as well as future perspectives.

miRNA let-7 family regulated by NEAT1 and ARID3A/NF-κB inhibits PRRSV-2 replication in vitro and in vivo

Porcine reproductive and respiratory syndrome (PRRS) is one of the most economically devastating diseases affecting the swine industry worldwide. To investigate the role of miRNAs in the infection and susceptibility of PRRS virus (PRRSV), twenty-four miRNA libraries were constructed and sequenced from PRRSV-infected and mock-infected Porcine alveolar macrophages (PAMs) of Meishan, Landrace, Pietrain and Qingping pigs at 9 hours post infection (hpi), 36 hpi, and 60 hpi. The let-7 family miRNAs were significantly differentially expressed between PRRSV-infected and mock-infected PAMs from 4 pig breeds. The let-7 family miRNAs could significantly inhibit PRRSV-2 replication by directly targeting the 3’UTR of the PRRSV-2 genome and porcine IL6, which plays an important role in PRRSV replication and lung injury. NEAT1 acts as a competing endogenous lncRNA (ceRNA) to upregulate IL6 by attaching let-7 in PAMs. EMSA and ChIP results confirmed that ARID3A could bind to the promoter region of pri-let-7a/let-7f/let-7d gene cluster and inhibit the expression of the let-7 family. Moreover, the NF-κB signaling pathway inhibits the expression of the let-7 family by affecting the nuclear import of ARID3A. The pEGFP-N1-let-7 significantly reduced viral infections and pathological changes in PRRSV-infected piglets. Taken together, NEAT1/ARID3A/let-7/IL6 play significant roles in PRRSV-2 infection and may be promising therapeutic targets for PRRS.

There are significant differences in susceptibility/resistance to PRRSV among different pig breeds. Especially the local pig breeds in China had strong resistance to PRRSV. However, due to the complexity of the interaction mechanism between pigs and PRRSV, the genetic mechanism leading to PRRSV susceptibility/resistance in different pig breeds is still unclear. MiRNAs play a vital regulatory role in immune response and development of PRRS. In this study, we found that the expression of miRNA let-7 family members were significantly different in PRRSV-infected/mock-infected PAMs from Pietrain, Qingping, Meishan, and Landrace pigs. Our findings illustrated that NEAT1/ARID3A/let-7/IL6 had a significant role in PRRSV-2 infection. What’s more, let-7 family could significantly reduce PRRSV infection and pathological changes in vitro and in vivo. This discovery provided a new idea for breeding PRRSV resistant pigs by revealing the molecular mechanism of PRRSV susceptibility in different pig breeds. Altogether, let-7 family have significant roles in PRRSV infection and may be promising therapeutic targets for PRRS.

Candesartan Attenuates Cisplatin-Induced Lung Injury by Modulating Oxidative Stress, Inflammation, and TLR-4/NF-κB, JAK1/STAT3, and Nrf2/HO-1 Signaling

Cisplatin (CIS) is an effective chemotherapeutic agent against different cancers. The use of CIS is associated with acute lung injury (ALI) and other adverse effects, and oxidative stress and inflammation were implicated in its toxic effects. Candesartan (CAN), an angiotensin II (Ang II) receptor blocker, showed beneficial effects against oxidative stress and inflammation. Therefore, this study investigated the potential of CAN to prevent CIS-induced oxidative stress, inflammation, and lung injury in rats, pointing to the involvement of TLR4/NF-κB, JAK1/STAT3, PPARγ, and Nrf2/HO-1 signaling. The rats received CAN (5 mg/kg) for 10 days and were challenged with a single dose of CIS (7 mg/kg) on day 7. CIS caused injury to the alveoli and the bronchial tree, increased lipid peroxidation, nitric oxide, myeloperoxidase, TLR-4, NF-κB p65, iNOS, TNF-α, IL-6, IL-1β, and caspase-3, and decreased cellular antioxidants and IL-6 in the lungs of rats. CAN effectively prevented tissue injury, suppressed TLR-4/ NF-κB signaling, and ameliorated oxidative stress, inflammatory markers, and caspase-3 in CIS-administered rats. CAN enhanced antioxidants and IL-10, decreased Ang II, increased Ang (1–7), suppressed the phosphorylation of JAK1 and STAT3, and upregulated SOCS3 in CIS-administered rats. These effects were associated with the downregulation of Keap1 and enhanced Nrf2, GCLC, HO-1, and PPARγ. In conclusion, CAN prevented CIS-induced lung injury by attenuating oxidative stress, suppressing TLR-4/NF-κB and JAK1/STAT3 signaling, Ang II, and pro-inflammatory mediators, and upregulating PPARγ, and Nrf2/HO-1 signaling.

Fluorous-Tagged Peptide Nanoparticles Ameliorate Acute Lung Injury via Lysosomal Stabilization and Inflammation Inhibition in Pulmonary Macrophages

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is a common respiratory critical syndrome that currently has no effective therapeutic interventions. Pulmonary macrophages play a principal role in the initiation and progression of the overwhelming inflammation in ALI/ARDS. Here, a type of fluorous-tagged bioactive peptide nanoparticle termed CFF13F is developed, which can be efficiently internalized by macrophages and suppress the excessive expression of cytokines and the overproduction of reactive oxygen species (ROS) triggered by lipopolysaccharide (LPS). The cytoprotective effect of CFF13F may be attributed to the lysosomal-stabilization property and regulation of the antioxidative system. Moreover, intratracheal pretreatment with CFF13F can effectively reduce local and systematic inflammation, and ameliorate pulmonary damage in an LPS-induced ALI murine model. The therapeutic efficacy of CFF13F is affected by the administration routes, and the local intratracheal injection is found to be the optimal choice for ALI treatment, with preferred biodistribution profiles. The present study provides solid evidence of the potent immunomodulatory bioactivity of the fluorous-tagged peptide nanoparticles CFF13F in vitro and in vivo, and sheds light on the development of novel efficient nanodrugs for ALI/ARDS.

The role of AMPK-Sirt1-autophagy pathway in the intestinal protection process by propofol against regional ischemia/reperfusion injury in rats

Intestinal ischemia/reperfusion (II/R) is a clinical event associated with high morbidity and mortality. AMP-activated protein kinase (AMPK), a central cellular energy sensor, is associated with oxidative stress and inflammation. However, whether the AMPK is involved in the II/R-induced intestinal injury and the underlying mechanism is yet to be elucidated. Propofol has a protective effect on organs; yet, its specific mechanism of action remains unclear. This study explored the role of the AMPK-Sirt1-autophagy pathway in intestinal injury, and whether propofol could reduce intestinal injury and investigated the mechanisms in a rat model of II/R injury as well as a cell model (IEC-6 cells) of hypoxia/reoxygenation (H/R). Propofol, AMPK agonist (AICAR) and AMPK inhibitor (Compound C) were then administered, respectively. The histopathological changes, cell viability and apoptosis were detected. Furthermore, the levels of proinflammatory factors, the activities of oxidative stress, diamine oxidase, and signaling pathway were also analyzed. The results demonstrated that the AMPK-Sirt1-autophagy pathway of intestine was activated after II/R or H/R. Propofol could further activate the pathway, which reduced intestinal injury, inhibited apoptosis, reversed inflammation and oxidative stress, and improved the 24-hour survival rate in II/R rats in vivo, and attenuated H/R-induced IEC-6 cell injury, oxidative stress, and apoptosis in vitro, as fine as changes in AICAR treatment. Compound C abrogated the protective effect of propofol on II/R and H/R-induced injury. These results suggested a crucial effect of AMPK on the mechanism of intestinal injury and might provide a new insight into the mechanism of propofol reducing II/R injury.

Anxiolytic and antidepressive potentials of rosmarinic acid: A review with a focus on antioxidant and anti-inflammatory effects

Depression and anxiety are the most prevalent neuropsychiatric disorders that have emerged as global health concerns. Anxiolytic and antidepressant drugs, such as benzodiazepines, selective serotonin reuptake inhibitors, monoamine oxidase inhibitors, and tricyclics, are the first line used in treating anxiety and depression. Although these drugs lack efficacy and have a delayed response time and numerous side effects, their widespread abuse and market continue to grow. Over time, traditional practices using natural and phytochemicals as alternative therapies to chemical drugs have emerged to treat many pathological conditions, including anxiety and depression. Recent preclinical studies have demonstrated that the phenolic compound, rosmarinic acid, is effective against several neuropsychiatric disorders, including anxiety and depression. In addition, rosmarinic acid showed various pharmacological effects, such as cardioprotective, hepatoprotective, lung protective, antioxidant, anti-inflammatory, and neuroprotective effects. However, the potentialities of the use of rosmarinic acid in the treatment of nervous system-related disorders, such as anxiety and depression, are less or not yet reviewed. Therefore, the purpose of this review was to present several preclinical and clinical studies, when available, from different databases investigating the effects of rosmarinic acid on anxiety and depression. These studies showed that rosmarinic acid produces advantageous effects on anxiety and depression through its powerful antioxidant and anti-inflammatory properties. This review will examine and discuss the possibility that the anxiolytic and anti-depressive effects of rosmarinic acid could be associated with its potent antioxidant and anti-inflammatory activities.

Adaptive mechanisms in no flow vs. low flow ischemia in equine jejunum epithelium: Different paths to the same destination

Intestinal ischemia reperfusion injury (IRI) is a frequent complication of equine colic. Several mechanisms may be involved in adaptation of the intestinal epithelium to IRI and might infer therapeutic potential, including hypoxia-inducible factor (HIF) 1α, AMP-activated protein kinase (AMPK), nuclear factor-erythroid 2-related factor 2 (NRF2), and induction of autophagy. However, the mechanisms supporting adaptation and thus cellular survival are not completely understood yet. We investigated the activation of specific adaptation mechanisms in both no and low flow ischemia and reperfusion simulated in equine jejunum epithelium in vivo. We found an activation of HIF1α in no and low flow ischemia as indicated by increased levels of HIF1α target genes and phosphorylation of AMPKα tended to increase during ischemia. Furthermore, the protein expression of the autophagy marker LC3B in combination with decreased expression of nuclear-encoded mitochondrial genes indicates an increased rate of mitophagy in equine intestinal IRI, possibly preventing damage by mitochondria-derived reactive oxygen species (ROS). Interestingly, ROS levels were increased only shortly after the onset of low flow ischemia, which may be explained by an increased antioxidative defense, although NFR2 was not activated in this setup. In conclusion, we could demonstrate that a variety of adaptation mechanisms manipulating different aspects of cellular homeostasis are activated in IRI irrespective of the ischemia model, and that mitophagy might be an important factor for epithelial survival following small intestinal ischemia in horses that should be investigated further.

Poldip2 knockdown protects against lipopolysaccharide-induced acute lung injury via Nox4/Nrf2/NF-κB signaling pathway

Polymerase δ-interacting protein 2 (Poldip2) has been reported to mediate acute lung injury (ALI); however, the underlying mechanism is not fully explored. Male C57BL/6 mice and A549 cells were used to establish the lipopolysaccharide (LPS)-induced ALI model, then the expression of Poldip2 and its effect on oxidative stress and the resulting inflammation were detected. Adeno-associated virus serotype 6 (AAV6) mediated Poldip2 knockdown was transfected into mice via intratracheal atomization. And A549 cells stimulated with LPS was used to further confirm our hypothesis in vitro. ML385, specifically inhibited the activation of the Nrf2 signaling pathway. Our data suggested that LPS stimulation remarkably increased protein levels of Nox4 and p-P65, activities of NADPH and MPO, and generation of ROS, TNF-α, and IL-1β while decreased protein levels of Nrf2 and HO-1 compared with those in NC shRNA + Saline group, which were obviously reversed by Poldip2 knockdown. Concomitantly, Poldip2 knockdown dramatically reduced contents of MDA and enhanced activities of SOD and GSH-Px compared to NC shRNA + LPS group. In vitro, we found that knockdown of Poldip2 significantly reversed LPS-induced increase protein levels of Nox4 and p-P65, activity of NADPH, and generation of ROS, TNF-α, and IL-1β, and decrease protein levels of Nrf2 and HO-1, ML385 pretreatment reversed the effects of Poldip2 knockdown mentioned above. Our study indicated that Poldip2 knockdown alleviates LPS-induced ALI via inhibiting Nox4/Nrf2/NF-κB signaling pathway.

The Role of Nrf2 in Pulmonary Fibrosis: Molecular Mechanisms and Treatment Approaches

Pulmonary fibrosis is a chronic, progressive, incurable interstitial lung disease with high mortality after diagnosis and remains a global public health problem. Despite advances and breakthroughs in understanding the pathogenesis of pulmonary fibrosis, there are still no effective methods for the prevention and treatment of pulmonary fibrosis. The existing treatment options are imperfect, expensive, and have considerable limitations in effectiveness and safety. Hence, there is an urgent need to find novel therapeutic targets. The nuclear factor erythroid 2-related factor 2 (Nrf2) is a central regulator of cellular antioxidative responses, inflammation, and restoration of redox balance. Accumulating reports reveal that Nrf2 activators exhibit potent antifibrosis effects and significantly attenuate pulmonary fibrosis in vivo and in vitro. This review summarizes the current Nrf2-related knowledge about the regulatory mechanism and potential therapies in the process of pulmonary fibrosis. Nrf2 orchestrates the activation of multiple protective genes that target inflammation, oxidative stress, fibroblast–myofibroblast differentiation (FMD), and epithelial–mesenchymal transition (EMT), and the mechanisms involve Nrf2 and its downstream antioxidant, Nrf2/HO−1/NQO1, Nrf2/NOX4, and Nrf2/GSH signaling pathway. We hope to indicate potential for Nrf2 system as a therapeutic target for pulmonary fibrosis.

Targeting Nrf2 in ischemia-reperfusion alleviation: From signaling networks to therapeutic targeting

The nuclear factor erythroid 2-related factor 2 (Nrf2) is a master regulator of redox balance and it responds to various cell stresses that oxidative stress is the most well-known one. The Nrf2 should undergo nuclear translocation to exert its protective impacts and decrease ROS production. On the other hand, ischemic/reperfusion (I/R) injury is a pathological event resulting from low blood flow to an organ and followed by reperfusion. The I/R induces cell injury and organ dysfunction. The present review focuses on Nrf2 function in alleviation of I/R injury. Stimulating of Nrf2 signaling ameliorates I/R injury in various organs including lung, liver, brain, testis and heart. The Nrf2 enhances activity of antioxidant enzymes to reduce ROS production and prevent oxidative stress-mediated cell death. Besides, Nrf2 reduces inflammation via decreasing levels of pro-inflammatory factors including IL-6, IL-1β and TNF-α. Nrf2 signaling is beneficial in preventing apoptosis and increasing cell viability. Nrf2 induces autophagy to prevent apoptosis during I/R injury. Furthermore, it can interact with other molecular pathways including PI3K/Akt, NF-κB, miRNAs, lncRNAs and GSK-3β among others, to ameliorate I/R injury. The therapeutic agents, most of them are phytochemicals such as resveratrol, berberine and curcumin, induce Nrf2 signaling in I/R injury alleviation.

Mechanistic Understanding of Lung Inflammation: Recent Advances and Emerging Techniques

Acute respiratory distress syndrome (ARDS) is a life-threatening lung injury characterized by an acute inflammatory response in the lung parenchyma. Hence, it is considered as the most appropriate clinical syndrome to study pathogenic mechanisms of lung inflammation. ARDS is associated with increased morbidity and mortality in the intensive care unit (ICU), while no effective pharmacological treatment exists. It is very important therefore to fully characterize the underlying pathobiology and the related mechanisms, in order to develop novel therapeutic approaches. In vivo and in vitro models are important pre-clinical tools in biological and medical research in the mechanistic and pathological understanding of the majority of diseases. In this review, we will present data from selected experimental models of lung injury/acute lung inflammation, which have been based on clinical disorders that can lead to the development of ARDS and related inflammatory lung processes in humans, including ventilation-induced lung injury (VILI), sepsis, ischemia/reperfusion, smoke, acid aspiration, radiation, transfusion-related acute lung injury (TRALI), influenza, Streptococcus (S.) pneumoniae and coronaviruses infection. Data from the corresponding clinical conditions will also be presented. The mechanisms related to lung inflammation that will be covered are oxidative stress, neutrophil extracellular traps, mitogen-activated protein kinase (MAPK) pathways, surfactant, and water and ion channels. Finally, we will present a brief overview of emerging techniques in the field of omics research that have been applied to ARDS research, encompassing genomics, transcriptomics, proteomics, and metabolomics, which may recognize factors to help stratify ICU patients at risk, predict their prognosis, and possibly, serve as more specific therapeutic targets.

Ginkgolide C Alleviates Acute Lung Injury Caused by Paraquat Poisoning via Regulating the Nrf2 and NF-κB Signaling Pathways

Paraquat (PQ), a highly toxic herbicide and primary attack for lung, results in severe acute lung injury (ALI) appeared as evident oxidative stress, inflammation, and apoptosis. Increasing evidence elucidates that nuclear factor erythroid-2-related factor 2 (Nrf2) and its associated nuclear factor-κB (NF-κB) exhibit many merits for protection of ALI by coordinating a fine-turned response to oxidative stress, inflammation, and apoptosis. Ginkgolide C (GC) has been reported to be a safe and potent therapeutic agent against ALI. However, whether GC could protect ALI induced by PQ poisoning and the possible underlining mechanisms have remained not to be fully elucidated. A rat model of ALI and a model of acute type II alveolar epithelial cell (RLE-6TN) injury constructed by exposure to PQ were applied to discuss the protective effect of GC. Furthermore, Nrf2 gene silencing RLE-6TN cells were used to discuss the exact mechanism. We confirmed that GC significantly ameliorated the histopathological damages, ultrastructural changes, lung injury score, W/D ratio, and Hyp activity of lung tissue and inhibited polymorphonuclear neutrophil (PMN) infiltration after PQ poisoning. Further results revealed that GC remarkably activated Nrf2-based cytoprotective system and inhibited NF-κB-induced inflammatory injury as well as apoptosis. Taken together, we concluded that GC preserved protection of PQ-induced ALI via the Nrf2-NF-κB dependent signal pathway, which may provide us novel insights into the treatment strategies for PQ poisoning.

Isoliquiritin apioside relieves intestinal ischemia/reperfusion-induced acute lung injury by blocking Hif-1α-mediated ferroptosis

Isoliquiritin apioside (IA), a critical ingredient of Glycyrrhizae radix et rhizoma, has been unveiled to possess remarkable pharmacological activity against oxidative stress and inflammation. However, the potential roles of IA in intestinal ischemia/reperfusion (I/R)-induced acute lung injury (ALI) have not been reported yet. In the present study, we explored the effects of IA on I/R-induced ALI, and also clarified the possible mechanisms. To mimic intestinal I/R-induced ALI, the mice were subjected to 60 min of intestinal ischemia via clamping of the superior mesenteric artery followed by 60 min of reperfusion. IA was administered orally (20 mg/kg/day and 50 mg/kg/day) for 7 consecutive days before intestinal I/R. Lung epithelial MLE-2 cells were subjected to hypoxia for 2 h and regeneration for 3 h to mimic in vitro ALI. The results showed that IA administration prevented intestinal I/R-induced lung injury, inflammation and edema. Also, IA administration decreased the level of ferroptosis in murine lung tissues challenged with intestinal I/R. In terms of mechanism, IA administration inhibited the protein upregulation of Hif-1α and HO-1 in mice with ALI. In vitro experiments further demonstrated that IA treatment could inhibit the mRNA and protein levels of Hif-1α in hypoxia/regeneration (H/R)-induced MLE-2 cells in a concentration-dependent manner. Hif-1α stabilizer molidustat itself also significantly promoted ferroptosis of MLE-2 cells. And Hif-1α activation increased the mRNA levels of Ptgs2 and Acsl4 but decreased the mRNA level of Gpx4 in H/R-induced MLE-2 cells treated with IA. Taken together, our study unveiled IA could protect against intestinal I/R-induced ALI by decreasing lung epithelial ferroptosis in a Hif-1α-dependent manner.

Dl-3-n-Butylphthalide Improves Neuroinflammation in Mice with Repeated Cerebral Ischemia-Reperfusion Injury through the Nrf2-Mediated Antioxidant Response and TLR4/MyD88/NF-κB Signaling Pathway

Increasing evidence shows that oxidative stress and neuroinflammation play a crucial role in the pathology of vascular dementia (VD). Previously, we have found that Dl-3-n-butylphthalide (NBP) has antioxidant and anti-inflammatory activities in VD, whereas little is known about its mechanism. Therefore, the objective of our study was to explore the contribution of nuclear factor erythroid-2 related factor 2 (Nrf2) to NBP and its effects on anti-inflammatory activity in a mouse model of VD. Our studies revealed that NBP could effectively mitigate cognitive deficits, neuron cell loss, and apoptosis in mice subjected to repeated cerebral ischemia-reperfusion (RCIR). Additionally, NBP promoted both the expression of brain-derived neurotrophic factor (BDNF) and tyrosine receptor kinase B (TrkB) in hippocampus tissue. NBP exhibited antioxidant activity by enhancing Nrf2 nuclear accumulation, increasing HO-1 and NQO1 expression, enhancing SOD activity, and inhibiting RCIR-induced MDA and 8-iso PGF2α generation in the hippocampus. NBP also significantly inhibited TLR4/MyD88/NF-κB signaling and suppressed microglial proliferation and the production of proinflammatory mediators in RCIR mice. Importantly, the antioxidant, antineuroinflammatory, and neuroprotective effects of NBP above were abolished by Nrf2 knockout. Collectively, these results indicated the effects of NBP on neuroinflammation were strongly associated with the Nrf2 pathway. Modulation of TLR4/MyD88/NF-κB pathway by Nrf2 is involved in the neuroprotective effect of NBP against VD induced by RCIR injury. With antioxidant and anti-neuroinflammatory properties, NBP could be a promising drug candidate for the prevention and/or treatment of VD and other neuroinflammatory disorders.

Melatonin attenuates LPS-induced pyroptosis in acute lung injury by inhibiting NLRP3-GSDMD pathway via activating Nrf2/HO-1 signaling axis

Acute lung injury (ALI)/ acute respiratory distress syndrome (ARDS) is featured by intensive inflammatory responses and oxidative stress, which lead to cytokine storms and pyroptosis. Here, we aimed to investigate whether melatonin was capable of alleviating LPS-induced ALI via activating the nuclear factor erythroid 2-related factor 2/heme oxygenase 1 (Nrf2/HO-1) signaling axis and inhibiting pyroptosis. Mice were injected with melatonin (30 mg/kg) intraperitoneally for consecutive five days before LPS instillation intratracheally, and human alveolar epithelial cell (AECⅡ) A549 cell lines and murine macrophages Raw264.7 cell lines were pretreated with melatonin (400 μM) before LPS (10 μg/ml) stimulation. The result demonstrated that LPS induced obvious lung injury characterized by alveolar damage, neutrophil infiltration and lung edema as well as the reduction of the survival rate of mice, which were totally reversed by melatonin pretreatment. Mechanistically, melatonin pretreatment activated nuclear factor erythroid2-related factor (Nrf) 2 signaling, subsequently, drove antioxidant pathways including significant increases in the expression of Nrf2, HO-1, NQO1, Mn-SOD and Catalase in vivo and in vitro. Simultaneously, melatonin inhibited ROS and MDA overproduction, iNOS expression as well as TNF-α and IL-1β expression and release. Furthermore, melatonin inhibited LPS-induced pyroptosis by reversing the overexpression of NLRP3, Caspase-1, IL-1β, IL-18 and GSDMD-N, as well as LDH release and TUNEL-positive cells in A549 cells and Raw264.7 cells. Overall, the current study suggests that melatonin exerts protective roles on LPS-induced ALI and pyroptosis by inhibiting NLRP3-GSDMD pathway via activating Nrf2/HO-1 signaling axis.

Acute lung inflammation induced by zinc oxide nanoparticles: Evolution and intervention via NRF2 activator

Zinc oxide nanoparticles (ZnONPs) are widely used worldwide. Human inhalation exposure to ZnONPs induces acute lung inflammation (ALI); however, the characteristics and therapeutic targets of ALI are unclear. In this study, female C57BL/6J mice were subjected to a single intratracheal instillation of 20 μg of ZnONPs. Increased lung malondialdehyde levels and decreased total antioxidant capacity at 6 h, as well as increased lactate dehydrogenase levels in bronchoalveolar lavage fluid (BALF) at 1 day (d) post treatment were observed. A significant inflammatory response was observed at 3 d and 7 d, as evidenced by increased leukocyte numbers and total protein concentration in BALF, and histological abnormalities. Pulmonary NRF2 signaling was significantly activated at 3 d post treatment. To investigate a protective role of NRF2 activator against ZnONP-induced ALI, the mice were intraperitoneally injected with 2-cyano-3,12-dioxooleana-1,9-dien-28-imidazolide (CDDO-Im) (2 mg/kg) 1 d before and 1 d after ZnONPs treatment. CDDO-Im significantly decreased leukocyte numbers and total protein concentration in BALF and pulmonary inflammatory gene expression, and ameliorated histopathological abnormalities induced by ZnONPs. Collectively, the present study indicates that ZnONPs exposure leads to oxidative stress, cell injury and inflammation in the lung successively. Moreover, the NRF2 activator protects against ZnONPs-induced ALI.

Paraquat Induces Lung Injury via miR-199-Mediated SET in a Mouse Model

Objective: To explore the molecular mechanism of lung injury caused by paraquat (PQ) poisoning by investigating miR-199-mediated SET.

Methods: A paraquat poisoning model was established in C57BL/6 male mice via intraperitoneal injection of paraquat. The mice were transfected with miR-199 siRNA and or mimic. After 14 days of treatment, pathophysiological changes of the lung were observed and lung tissue was analyzed via Hematoxylin-Eosin staining. The levels of miR-199, SETs, surfactant protein SP-A and SP-B, and inflammatory and oxidative factors were analyzed by qPCR, Western Blot, and ELISA kits.

Results: A acute lung-injury (ALI) model was established using PQ treatment and confirmed with edema of pulmonary endothelium with low electronic density of endothelial cytoplasm, presence of protein-rich fluid, and numerous erythrocytes in alveolar space, concentric figures of damaged tubular myelin, alveolar destruction, and increase in inflammatory cell numbers. Compared with the control group, miR-199 and SET levels were reduced in the PQ-treated group. miR-199 siRNA increased the SET level, inflammatory and oxidative levels, and reduced the levels of SP-A and SP-B, and miR-199 mimic reduced the SET level, inflammatory and oxidative levels, and increased the levels of SP-A and SP-B. PQ treatment reduced miR-199 level.

Conclusion: Paraquat induces ALI by affecting miR-199-mediated SET.

Ellagic Acid Alleviates Diquat-Induced Jejunum Oxidative Stress in C57BL/6 Mice through Activating Nrf2 Mediated Signaling Pathway

Ellagic acid (EA) is the main constituent found in pomegranate rind, which has anti-inflammatory and antioxidant effects. However, whether EA can alleviate diquat-induced oxidative stress is still unknown. Here, the effects and mechanisms of EA on jejunum oxidative stress induced by diquat was investigated. Oxidative stress was induced in mice by administrating diquat (25 mg/kg body weight) followed by treatment with 100 mg/kg body weight EA for 5 days. Results showed that oral administration of EA significantly ameliorated diquat-induced weight loss and oxidative stress (p < 0.05) evidenced by reduced ROS production in the jejunum. Furthermore, EA up-regulated the mRNA expression of the antioxidant enzymes (Nrf2, GPX1 and HO-1) when mice were challenged with diquat, compared with the diquat group (p < 0.05). Importantly, pharmacological inhibition of Nrf2 by ML385 counteracted the EA-mediated alleviation of jejunum oxidative stress, as evidence by body weight and ROS production. Also, immunohistochemistry staining confirmed the markedly decreased jejunal Nrf2 expression. The up-regulated effect on NQO1 and HO-1 mRNA expression induced by EA was diminished in mice treated with ML385 (p < 0.05). Together, our results demonstrated that therapeutic and preventative EA treatment was effective in reducing weight loss and oxidative stress induced by diquat through the Nrf2 mediated signaling pathway.

Activation of the GPX4/TLR4 Signaling Pathway Participates in the Alleviation of Selenium Yeast on Deltamethrin-Provoked Cerebrum Injury in Quails

Deltamethrin (DLM) is a member of pyrethroid pesticide widely applied for agriculture and aquaculture, and its residue in the environment seriously threatens the bio-safety. The cerebrum might be vulnerable to pesticide-triggered oxidative stress. However, there is no specific antidote for treating DLM-triggered cerebral injury. Selenium (Se) is an essential trace element functionally forming selenoprotein glutathione peroxidase (GPX) in antioxidant defense. Se yeast (SY) is a common and effective organic form of Se supplement with high selenomethionine content. Accordingly, this study focused on investigating the therapeutic potential of SY on DLM-induced cerebral injury in quails after chronically exposing to DLM and exploring the underlying mechanisms. Quails were treated with/without SY (0.4 mg kg^-1 SY added in standard diet) in the presence/absence of DLM (45 mg kg^-1 body weight intragastrically) for 12 weeks. The results showed SY supplementation ameliorated DLM-induced cerebral toxicity. Concretely, SY elevated the content of Se and increased GPX4 level in DLM-treated quail cerebrum. Furthermore, SY enhanced antioxidant defense system by upregulating nuclear factor-erythroid-2-related factor 2 (Nrf2) associated members. Inversely, SY diminished the changes of apoptosis- and inflammation-associated proteins and genes including toll-like receptor 4 (TLR4). Collectively, our results suggest that dietary SY protects against DLM-induced cerebral toxicity in quails via positively regulating the GPX4/TLR4 signaling pathway. GPX4 may be a potential therapeutic target for insecticide-induced biotoxicity.

Silencing of Nrf2 in Litopenaeus vannamei, decreased the antioxidant capacity, and increased apoptosis and autophagy

Nuclear factor E2-related factor 2 (Nrf2) is a multifunctional transcription factor that plays an important role in antioxidant activities. However, its effect on antioxidant capacity in Litopenaeus vannamei, an economically important crustacean, remains unclear. In this study, the role of Nrf2 in response to oxidative stress in L. vannamei was determined by its effect on relevant gene expression and enzymatic activity. Nrf2 was cloned and analyzed. Results revealed that Nrf2 contains a 1575 bp open reading frame encoding 524 amino acids and a conserved bZIP Maf domain. The sequence similarity of Nrf2 between L. vannamei and Homarus americanus is 81%. Although the Nrf2 expression was detected in all tissues, the Nrf2 expression levels were the highest in the hepatopancreas, followed by the eyestalk and muscle. RNA interference significantly decreased the expression of antioxidant-related genes (SOD, GPX, CAT, Trx, and HO-1; p < 0.05), significantly upregulated the expression of autophagy genes (Atg3, Atg4, Atg5, Atg10, and Atg12; p < 0.05) and apoptosis genes (Caspase-3 and P53; p < 0.05). Moreover, SOD, CAT, and GPX enzyme activities decreased whereas the MDA activity increased. The histological results of the shrimp injected with dsRNA-Nrf2 showed that the hepatic tubules were irregularly arranged, the lumen was abnormal, and a few hepatic tubules were significantly enlarged compared with those of the dsRNA-EGFP group. The hepatocytes were also vacuolated. In conclusion, this study provided evidence that Nrf2 is involved in the regulation of antioxidant capacity, oxidative stress, apoptosis, and autophagy in shrimp.

Kindlin-2 Mediates Lipopolysaccharide-Induced Acute Lung Injury Partially via Pyroptosis in Mice

Acute lung injury (ALI) is characteristic of the wholesale destruction of the lung endothelial barrier, which results in protein-rich lung edema, influx of pro-inflammatory leukocytes, and intractable hypoxemia, contributing to high mortality. Kindlin-2 is involved in the process of tumor- and wound healing-associated inflammation. However, the effects of kindlin-2 on lipopolysaccharide (LPS)-induced ALI and its mechanisms remain unknown. In this study, we found that the concentration of kindlin-2 was elevated in the lungs of ALI mice. The specific deletion of kindlin-2 by kindlin-2 siRNA attenuated the severity of lung injury, which was demonstrated by the reduced number of pro-inflammatory cells in bronchoalveolar lavage fluid and lung wet/dry weight ratio, and ameliorated pathologic changes in the lungs of ALI mice. Furthermore, kindlin-2 siRNA decreased the mRNA levels of pro-inflammatory factors (IL-1β, IL-6, and TNF-α) and the protein levels of pyroptosis-related proteins. In vitro studies confirmed that LPS + ATP promoted the expressions of pro-inflammatory factors and pyroptosis-related proteins, which was prevented by kindlin-2 siRNA pretreatment in endothelial cells (ECs). In conclusion, inhibition of kindlin-2 developes protective effects against LPS-induced ALI and the cytotoxicity of ECs, which may depend on blocking pyroptosis.