The role of Nrf2 in acute kidney injury: Novel molecular mechanisms and therapeutic approaches

Renoprotective effect of Nesfatin-1 in Adenine-Induced Chronic kidney Disease: An in vitro and in vivo study

Chronic Kidney Disease (CKD) presents a significant global health challenge with limited treatment options. Nesfatin-1, an anorexigenic peptide, has demonstrated antioxidant, anti-inflammatory, and anti-apoptotic properties in various diseases. However, the role of nesfatin-1 in CKD remains unclear. This study investigates the potential renoprotective effects of nesfatin-1 in adenine-induced CKD mice and in NRK-52E renal epithelial cells. Male C57BL/6J mice and NRK-52E renal epithelial cells were administered adenine to induce CKD. Various aspects of renal function, histopathology, oxidative stress, inflammation, apoptosis, and renal interstitial fibrosis were assessed and downstream pathways were investigated. Adenine-fed mice exhibited reduced nesfatin-1 expression and increased markers of kidney damage, including elevated blood urea nitrogen (BUN), serum creatinine, and histological abnormalities, reactive oxygen species (ROS), inflammation, apoptosis, and fibrosis. Treatment with nesfatin-1 in adenine induced mice significantly reversed these changes. Nesfatin-1 also lowered calcium levels and the expression of inflammatory markers, including IL-1β, IL-6, TNF-α, and Nf-kB. Furthermore, nesfatin-1 reduced the expression of apoptotic markers (Caspase-3, Caspase-1, Bax/Bcl2 ratio) and restored the balance of Bcl2 and MMP. Lastly, nesfatin-1 attenuated fibrotic markers (Tgf-β, Smad2/3,4, type IV collagen, α-SMA) in both adenine-induced CKD mice and NRK-52E cells. In conclusion, our results suggest that nesfatin-1 may enhance kidney function in adenine-induced CKD mice and NRK-52E cells. The renoprotective effects of nesfatin-1 are likely associated with its antioxidant, anti-inflammatory, anti-apoptotic, and anti-fibrotic properties.

Caffeine and neonatal acute kidney injury

Acute kidney injury is one of the most threatening diseases in neonates, with complex pathogenesis and limited treatment options. Caffeine is a commonly used central nervous system stimulant for treating apnea in preterm infants. There is compelling evidence that caffeine may have potential benefits for preventing neonatal acute kidney injury, but comprehensive reports are lacking in this area. Hence, this review aims to provide a summary of clinical data on the potential benefits of caffeine in improving neonatal acute kidney injury. Additionally, it delves into the molecular mechanisms underlying caffeine's effects on acute kidney injury, with a focus on various aspects such as oxidative stress, adenosine receptors, mitochondrial dysfunction, endoplasmic reticulum stress, inflammasome, autophagy, p53, and gut microbiota. The ultimate goal of this review is to provide information for healthcare professionals regarding the link between caffeine and neonatal acute kidney injury and to identify gaps in our current understanding.

Hyperbaric Oxygen Reduces Oxidative Stress Impairment and DNA Damage and Simultaneously Increases HIF-1α in Ischemia-Reperfusion Acute Kidney Injury

The central exacerbating factor in the pathophysiology of ischemic-reperfusion acute kidney injury (AKI) is oxidative stress. Lipid peroxidation and DNA damage in ischemia are accompanied by the formation of 3-nitrotyrosine, a biomarker for oxidative damage. DNA double-strand breaks (DSBs) may also be a result of postischemic AKI. γH2AX(S139) histone has been identified as a potentially useful biomarker of DNA DSBs. On the other hand, hypoxia-inducible factor (HIF) is the "master switch" for hypoxic adaptation in cells and tissues. The aim of this research was to evaluate the influence of hyperbaric oxygen (HBO) preconditioning on antioxidant capacity estimated by FRAP (ferric reducing antioxidant power) and ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) assay, as well as on oxidative stress parameter 3-nitrotyrosine, and to assess its effects on γH2AX(S139), HIF-1α, and nuclear factor-κB (NF-κB) expression, in an experimental model of postischemic AKI induced in spontaneously hypertensive rats. The animals were divided randomly into three experimental groups: sham-operated rats (SHAM, n = 6), rats with induced postischemic AKI (AKI, n = 6), and group exposed to HBO preconditioning before AKI induction (AKI + HBO, n = 6). A significant improvement in the estimated glomerular filtration rate, eGFR, in AKI + HBO group (p < 0.05 vs. AKI group) was accompanied with a significant increase in plasma antioxidant capacity estimated by FRAP (p < 0.05 vs. SHAM group) and a reduced immunohistochemical expression of 3-nitrotyrosine and γH2AX(S139). Also, HBO pretreatment significantly increased HIF-1α expression (p < 0.001 vs. AKI group), estimated by Western blot and immunohistochemical analysis in kidney tissue, and decreased immunohistochemical NF-κB renal expression (p < 0.01). Taking all of these results together, we may conclude that HBO preconditioning has beneficial effects on acute kidney injury induced in spontaneously hypertensive rats.

The Modulatory Effects of Curcumin on the Gut Microbiota: A Potential Strategy for Disease Treatment and Health Promotion

Curcumin (CUR) is a lipophilic natural polyphenol that can be isolated from the rhizome of turmeric. Studies have proposed that CUR possesses a variety of biological activities. Due to its anti-inflammatory and antioxidant properties, CUR shows promise in the treatment of inflammatory bowel disease, while its anti-obesity effects make it a potential therapeutic agent in the management of obesity. In addition, curcumin's ability to prevent atherosclerosis and its cardiovascular benefits further expand its potential application in the treatment of cardiovascular disease. Nevertheless, owing to the limited bioavailability of CUR, it is difficult to validate its specific mechanism of action in the treatment of diseases. However, the restricted bioavailability of CUR makes it challenging to confirm its precise mode of action in disease treatment. Recent research indicates that the oral intake of curcumin may lead to elevated levels of residual curcumin in the gastrointestinal system, hinting at curcumin's potential to directly influence gut microbiota. Furthermore, the ecological dysregulation of the gut microbiota has been shown to be critical in the pathogenesis of human diseases. This review summarizes the impact of gut dysbiosis on host health and the various ways in which curcumin modulates dysbiosis and ameliorates various diseases caused by it through the administration of curcumin.

Antioxidative Sirt1 and the Keap1-Nrf2 Signaling Pathway Impair Inflammation and Positively Regulate Autophagy in Murine Mammary Epithelial Cells or Mammary Glands Infected with Streptococcus uberis

Streptococcus uberis mastitis in cattle infects mammary epithelial cells. Although oxidative responses often remove intracellular microbes, S. uberis survives, but the mechanisms are not well understood. Herein, we aimed to elucidate antioxidative mechanisms during pathogenesis of S. uberis after isolation from clinical bovine mastitis milk samples. S. uberis's in vitro pathomorphology, oxidative stress biological activities, transcription of antioxidative factors, inflammatory response cytokines, autophagosome and autophagy functions were evaluated, and in vivo S. uberis was injected into the fourth mammary gland nipple of each mouse to assess the infectiousness of S. uberis potential molecular mechanisms. The results showed that infection with S. uberis induced early oxidative stress and increased reactive oxygen species (ROS). However, over time, ROS concentrations decreased due to increased antioxidative activity, including total superoxide dismutase (T-SOD) and malondialdehyde (MDA) enzymes, plus transcription of antioxidative factors (Sirt1, Keap1, Nrf2, HO-1). Treatment with a ROS scavenger (N-acetyl cysteine, NAC) before infection with S. uberis reduced antioxidative responses and the inflammatory response, including the cytokines IL-6 and TNF-α, and the formation of the Atg5-LC3II/LC3I autophagosome. Synthesis of antioxidants determined autophagy functions, with Sirt1/Nrf2 activating autophagy in the presence of S. uberis. This study demonstrated the evasive mechanisms of S. uberis in mastitis, including suppressing inflammatory and ROS defenses by stimulating antioxidative pathways.

Prevention of the Lachnum polysaccharide and its selenium derivatives on cisplatin-induced acute kidney injury in mice

To investigate the renal protective effects of the polysaccharide LEP-1a and derivatives of selenium (SeLEP-1a) from Lachnum YM38, cisplatin (CP) was used to establish an acute kidney model. LEP-1a and SeLEP-1a could effectively reverse the decrease in renal index and improved renal oxidative stress. LEP-1a and SeLEP-1a significantly reduced the contents of the inflammatory cytokines. They could inhibit the release of cyclooxygenase 2 (COX-2) and nitric oxide synthase (iNOS) and increase the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and hemeoxygenase-1 (HO-1). At the same time, the PCR results indicated that SeLEP-1a could significantly inhibit the mRNA expression levels of toll-like receptor 4 (TLR4), nuclear factor-kB (NF-κB) p65 and inhibitor of kappa B-alpha (IκBα). Western blot analysis showed that LEP-1a and SeLEP-1a significantly downregulated the expression levels of Bcl-2-associated X protein (Bax) and cleaved caspase-3 and upregulated phosphatidylinositol 3-kinase (p-PI3K), protein kinase B (p-Akt) and B-cell lymphoma 2 (Bcl-2) protein expression levels in the kidney. LEP-1a and SeLEP-1a could improve CP-induced acute kidney injury by regulating the oxidative stress response, NF-κB-mediated inflammation and the PI3K/Akt-mediated apoptosis signalling pathway.

Umbelliferone attenuates cisplatin-induced acute kidney injury by inhibiting oxidative stress and inflammation via NRF2

In this study, we investigated the nephroprotective effects of Umbelliferone (UMB) against cisplatin-induced acute kidney injury (AKI). C57BL/6J mice were treated with cisplatin via a single intraperitoneal injection (25 mg/kg) with or without UMB (40 mg/kg/day) by gavage. Renal function, apoptosis, oxidative stress, inflammation, and mitochondrial function were analyzed to evaluate kidney injury. In vitro, human proximal tubule epithelial cells were treated with cisplatin, with or without UMB, for 24 h. Western blotting and immunohistochemistry were performed to explore the mechanisms underlying the nephroprotective effects of UMB. Cisplatin-induced renal dysfunction, including increases in blood urea nitrogen, serum creatinine, and renal tubular injury indices (NGAL and KIM-1), were significantly attenuated by UMB treatment, along with renal phenotypic changes and renal tubular injury, as evidenced by improved renal histology. Moreover, NRF2 was activated by UMB pretreatment, along with the inhibition of oxidative stress and inflammatory response, as evidenced by decreased levels of antioxidant genes and inflammatory cytokines in cisplatin-induced AKI. Our results demonstrate that UMB can protect against cisplatin-induced nephrotoxicity, which is mediated by the NRF2 signaling pathway via antioxidant and anti-inflammatory activities, suggesting the clinical potential of UMB for the treatment of AKI.

Apelin-13 alleviates contrast-induced acute kidney injury by inhibiting endoplasmic reticulum stress

Contrast-induced acute kidney injury (CI-AKI) is a severe complication associated with significant morbidity and mortality, and effective therapeutic strategies are still lacking. Apelin is an endogenous physiological regulator with antioxidative, anti-inflammatory and antiapoptotic properties. However, the role of apelin-13 in CI-AKI remains unclear. In our study, we found that the protein expression levels of apelin were significantly downregulated in rat kidney tissues and HK-2 cells during contrast media treatment. Moreover, we explored the protective effect of apelin-13 on renal tubule damage using in vitro and in vivo models of CI-AKI. Exogenous apelin-13 ameliorated endoplasmic reticulum stress, reactive oxygen species and apoptosis protein expression in contrast media-treated cells and rat kidney tissues. Mechanistically, the downregulation of endoplasmic reticulum stress contributed critically to the antiapoptotic effect of apelin-13. Collectively, our findings reveal the inherent mechanisms by which apelin-13 regulates CI-AKI and provide a prospective target for the prevention of CI-AKI.

Antioxidant nanozymes in kidney injury: mechanism and application

Excessive production of reactive oxygen species (ROS) in the kidneys is involved in the pathogenesis of kidney diseases, such as acute kidney injury (AKI) and diabetic kidney disease (DKD), and is the main reason for the progression of kidney injury. ROS can easily lead to lipid peroxidation and damage the tubular epithelial cell membrane, proteins and DNA, and other molecules, which can trigger cellular oxidative stress. Effective scavenging of ROS can delay or halt the progression of kidney injury by reducing inflammation and oxidative stress. With the development of nanotechnology and an improved understanding of nanomaterials, more researchers are applying nanomaterials with antioxidant activity to treat kidney injury. This article reviews the detailed mechanism between ROS and kidney injury, as well as the applications of nanozymes with antioxidant effects based on different materials for various kidney injuries. To better guide the applications of antioxidant nanozymes in kidney injury and other inflammatory diseases, at the end of this review we also summarize the aspects of nanozymes that need to be improved. An in-depth understanding of the role played by ROS in the occurrence and progression of kidney injury and the mechanism by which antioxidant nanozymes reduce oxidative stress is conducive to improving the therapeutic effect in kidney injury and inflammation-related diseases.

CCN2 Activates RIPK3, NLRP3 Inflammasome, and NRF2/Oxidative Pathways Linked to Kidney Inflammation

Inflammation is a key characteristic of both acute and chronic kidney diseases. Preclinical data suggest the involvement of the NLRP3/Inflammasome, receptor-interacting protein kinase-3 (RIPK3), and NRF2/oxidative pathways in the regulation of kidney inflammation. Cellular communication network factor 2 (CCN2, also called CTGF in the past) is an established fibrotic biomarker and a well-known mediator of kidney damage. CCN2 was shown to be involved in kidney damage through the regulation of proinflammatory and profibrotic responses. However, to date, the potential role of the NLRP3/RIPK3/NRF2 pathways in CCN2 actions has not been evaluated. In experimental acute kidney injury induced with folic acid in mice, CCN2 deficiency diminished renal inflammatory cell infiltration (monocytes/macrophages and T lymphocytes) as well as the upregulation of proinflammatory genes and the activation of NLRP3/Inflammasome-related components and specific cytokine products, such as IL-1β. Moreover, the NRF2/oxidative pathway was deregulated. Systemic administration of CCN2 to C57BL/6 mice induced kidney immune cell infiltration and activated the NLRP3 pathway. RIPK3 deficiency diminished the CCN2-induced renal upregulation of proinflammatory mediators and prevented NLRP3 modulation. These data suggest that CCN2 plays a fundamental role in sterile inflammation and acute kidney injury by modulating the RIKP3/NLRP3/NRF2 inflammatory pathways.

Impaired NRF2 Inhibits Recovery from Ischemic Reperfusion Injury in the Aging Kidney

Deteriorating kidney function is frequently observed in the elderly population, as well as vulnerability to acute kidney failure, such as ischemic/reperfusion injury (IRI), and inadequate recovery from IRI is one of the mechanisms of kidney dysfunction in the elderly. The potential mediators in the progression of kidney dysfunction in the aging kidney have not yet been clearly revealed. In this study, we investigated the role of nuclear factor erythroid 2-related factor 2 (NRF2), which is an essential regulator of cellular redox homeostasis, in restoring kidney function after IRI in the aging kidney. NRF2 expression decreased significantly in the kidneys of old mice, as well as histologic and functional renal recovery after IRI; 45-min renal pedicle clamping was retarded in old compared with young mice. Persistent renal injury during the recovery phase after IRI was aggravated in NRF2 knockout (KO) mice compared to wild-type mice. Oxidative stress occurred in NRF2 KO old mice during the IRI recovery phase along with decreased expression of mitochondrial OXPHOS-related proteins and a reduction in mitochondrial ATP content. In vitro, hypoxia/reoxygenation (H/R) injury was aggravated in senescent human proximal tubuloepithelial cells after NRF2 restriction using NRF2 siRNA, which also increased the level of oxidative stress and deteriorated mitochondrial dysfunction. Treating the mice with an NRF2 activator, CDDO-Me, alleviated the injury. These results suggest that NRF2 may be a therapeutic target for the aging kidney.

SerpinA3K Deficiency Reduces Oxidative Stress in Acute Kidney Injury

We previously showed that SerpinA3K is present in urine from rats and humans with acute kidney injury (AKI) and chronic kidney disease (CKD). However, the specific role of SerpinA3K during renal pathophysiology is unknown. To begin to understand the role of SerpinA3K on AKI, SerpinA3K-deficient (KOSA3) mice were studied 24 h after inducing ischemia/reperfusion (I/R) and compared to wild type (WT) mice. Four groups were studied: WT+S, WT+IR, KOSA3+S, and KOSA3+IR. As expected, I/R increased serum creatinine and BUN, with a GFR reduction in both genotypes; however, renal dysfunction was ameliorated in the KOSA3+IR group. Interestingly, the increase in UH₂O₂ induced by I/R was not equally seen in the KOSA3+IR group, an effect that was associated with the preservation of antioxidant enzymes' mRNA levels. Additionally, FOXO3 expression was initially greater in the KOSA3 than in the WT group. Moreover, the increase in BAX protein level and the decrease in Hif1a and Vegfa induced by I/R were not observed in the KOSA3+IR group, suggesting that these animals have better cellular responses to hypoxic injury. Our findings suggest that SerpinA3K is involved in the renal oxidant response, HIF1α/VEGF pathway, and cell apoptosis.

Simultaneous Elimination of Reactive Oxygen Species and Activation of Nrf2 by Ultrasmall Nanoparticles to Relieve Acute Kidney Injury

Excess reactive oxygen species (ROS) can induce serious acute kidney injury (AKI) to result in numerous deaths annually in clinical practice. Elimination of excess ROS by advanced nanotechnology is a very promising AKI therapy. In this Article, we report that PVP-stabilized and quercetin-functionalized ultrasmall Cu_2-xSe nanoparticles (abbreviated as CSPQ NPs) can efficiently scavenge ROS and increase the expression of intracellular antioxidative enzymes by activating the nuclear factor erythroid 2-related factor 2 (Nrf2) protein, which drastically alleviates the cellular oxidative stress. Our ultrasmall nanoparticles exhibit excellent biocompatibility. They can be rapidly accumulated into the injured kidney to simultaneously eliminate ROS and activate Nrf2 to improve the renal function. This work demonstrates the great potential of simultaneous elimination of ROS and activation of intracellular Nrf2 in treatment of AKI. It also highlights the potential of CSPQ NPs in protection and prevention of AKI.

The Effects of Quercetin on Apoptosis and Antioxidant Activity in a Renal Ischemia/Reperfusion Injury Animal Model

Renal ischemia-reperfusion injury (IRI) is considered as one of the most prevalent causes of acute kidney injury (AKI), which can happen in various clinical situations including hypovolemic shock, injury, thrombo-embolism, and after a kidney transplant. This paper aims to evaluate the reno-protective effects of Quercetin in induced ischemia/reperfusion injury by regulating apoptosis-related proteins, inflammatory cytokines, MMP-2, MMP-9, and nuclear factor kappa-light-chain-enhancer inactivated B cells (NF-kB) in rats. The male Wistar rats (n=32) were randomly divided into Sham, untreated IR, and Quercetin-treated IR (gavage and intraperitoneal). Quercetin was given orally and intraperitoneally one hour before inducing ischemia-reperfusion injury . After reperfusion, blood samples and kidneys were collected to assess renal function and inflammatory cytokines, apoptotic signaling proteins, and antioxidants. Urea, creatinine, and MDA levels improved in Quercetin-treated groups with different administration methods. In addition, the activities of other antioxidant in Quercetin-treated rats were higher than those in the IR group. Further, Quercetin inhibited NF-kB signaling, apoptosis-associated factors and produced matrix metalloproteinase protein in the kidneys of rats. Based on the findings, the antioxidant, anti-inflammatory, and anti-apoptotic effects of the Quercetin diminished renal ischemia-reperfusion injury in the rats significantly. It is suggested that a single dosage of Quercetin have a reno-protective impact in the case of renal I/R injury.

Insights into the Molecular Mechanisms of NRF2 in Kidney Injury and Diseases

Redox is a constant phenomenon in organisms. From the signaling pathway transduction to the oxidative stress during the inflammation and disease process, all are related to reduction-oxidation (redox). Nuclear factor erythroid 2-related factor 2 (NRF2) is a transcription factor targeting many antioxidant genes. In non-stressed conditions, NRF2 maintains the hemostasis of redox with housekeeping work. It expresses constitutively with basal activity, maintained by Kelch-like-ECH-associated protein 1 (KEAP1)-associated ubiquitination and degradation. When encountering stress, it can be up-regulated by several mechanisms to exert its anti-oxidative ability in diseases or inflammatory processes to protect tissues and organs from further damage. From acute kidney injury to chronic kidney diseases, such as diabetic nephropathy or glomerular disease, many results of studies have suggested that, as a master of regulating redox, NRF2 is a therapeutic option. It was not until the early termination of the clinical phase 3 trial of diabetic nephropathy due to heart failure as an unexpected side effect that we renewed our understanding of NRF2. NRF2 is not just a simple antioxidant capacity but has pleiotropic activities, harmful or helpful, depending on the conditions and backgrounds.

Jieduquyuziyin prescription promotes the efficacy of prednisone via upregulating Nrf2 in MRL/lpr kidneys

ETHNOPHARMACOLOGICAL RELEVANCE

The Jieduquyuziyin prescription (JP), a traditional Chinese medicine (TCM) formula, has been used as an approved hospital prescription to improve the efficacy of prednisone (Pred) in systemic lupus erythematosus (SLE) and lupus nephritis (LN) treatment. Although the synergistic effect of JP and Pred is prominent, the underlying mechanisms require further investigation.

AIM OF THE STUDY

To explore the key therapeutic targets of JP in improving the role of Pred in the treatment of LN.

MATERIALS AND METHODS

Lupus-prone female MRL/lpr mice were administered JP, Pred, or JP combined with Pred. The effect of JP on LN was estimated by evaluating renal function and inflammation levels in the kidneys. On this basis, RNA sequencing of kidney tissues was performed, and the differentially expressed genes were analyzed and summarized. The role of JP in the expression of nuclear factor erythroid 2-related factor 2 (NFE2L2 or Nrf2) in the kidneys was further confirmed by real-time PCR, immunohistochemistry, and western blotting.

RESULTS

JP combined with Pred exhibited the most remarkable therapeutic effect compared with JP or Pred alone. Transcriptome analysis indicated that Nrf2, a central mediator of the antioxidative response, was significantly upregulated by JP. Based on these results, we speculated that Nrf2 is a critical factor for JP, improving the efficacy of Pred in treating LN by notably suppressing the oxidative stress level in the kidneys. Furthermore, we found that Nrf2 expression decreased with the exacerbation of LN in MRL/lpr mice. In addition, the downregulated Nrf2 was notably restored after JP treatment, accompanied by suppressed oxidative stress levels in the kidneys. It includes inhibited accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA), restored mitochondrial membrane potential (MMP) levels, and increased antioxidant enzyme activity of superoxide dismutase (SOD).

CONCLUSIONS

Our findings show that JP increases Pred efficacy by increasing Nrf2 expression, implying that Nrf2 may be a promising therapeutic target for the treatment of LN.

Single-cell transcriptomics reveals common epithelial response patterns in human acute kidney injury

Background

Acute kidney injury (AKI) occurs frequently in critically ill patients and is associated with adverse outcomes. Cellular mechanisms underlying AKI and kidney cell responses to injury remain incompletely understood.

Methods

We performed single-nuclei transcriptomics, bulk transcriptomics, molecular imaging studies, and conventional histology on kidney tissues from 8 individuals with severe AKI (stage 2 or 3 according to Kidney Disease: Improving Global Outcomes (KDIGO) criteria). Specimens were obtained within 1–2 h after individuals had succumbed to critical illness associated with respiratory infections, with 4 of 8 individuals diagnosed with COVID-19. Control kidney tissues were obtained post-mortem or after nephrectomy from individuals without AKI.

Results

High-depth single cell-resolved gene expression data of human kidneys affected by AKI revealed enrichment of novel injury-associated cell states within the major cell types of the tubular epithelium, in particular in proximal tubules, thick ascending limbs, and distal convoluted tubules. Four distinct, hierarchically interconnected injured cell states were distinguishable and characterized by transcriptome patterns associated with oxidative stress, hypoxia, interferon response, and epithelial-to-mesenchymal transition, respectively. Transcriptome differences between individuals with AKI were driven primarily by the cell type-specific abundance of these four injury subtypes rather than by private molecular responses. AKI-associated changes in gene expression between individuals with and without COVID-19 were similar.

Conclusions

The study provides an extensive resource of the cell type-specific transcriptomic responses associated with critical illness-associated AKI in humans, highlighting recurrent disease-associated signatures and inter-individual heterogeneity. Personalized molecular disease assessment in human AKI may foster the development of tailored therapies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13073-022-01108-9.

Renal Hypoxic Reperfusion Injury-on-Chip Model for Studying Combinational Vitamin Therapy

Renal ischemic-reperfusion injury decreases the chances of long-term kidney graft survival and may lead to the loss of a transplanted kidney. During organ excision, the cycle of warm ischemia from the donor and cold ischemia is due to storage in a cold medium after revascularization following organ transplantation. The reperfusion of the kidney graft activates several pathways that generate reactive oxygen species, forming a hypoxic-reperfusion injury. Animal models are generally used to model and investigate renal hypoxic-reperfusion injury. However, these models face ethical concerns and present a lack of robustness and intraspecies genetic variations, among other limitations. We introduce a microfluidics-based renal hypoxic-reperfusion (RHR) injury-on-chip model to overcome current limitations. Primary human renal proximal tubular epithelial cells and primary human endothelial cells were cultured on the apical and basal sides of a porous membrane. Hypoxic and normoxic cell culture media were used to create the RHR injury-on-chip model. The disease model was validated by estimating various specific hypoxic biomarkers of RHR. Furthermore, retinol, ascorbic acid, and combinational doses were tested to devise a therapeutic solution for RHR. We found that combinational vitamin therapy can decrease the chances of RHR injury. The proposed RHR injury-on-chip model can serve as an alternative to animal testing for injury investigation and the identification of new therapies.

Salvianolate ameliorates renal tubular injury through the Keap1/Nrf2/ARE pathway in mouse kidney ischemia-reperfusion injury

ETHNOPHARMACOLOGICAL RELEVANCE

Acute kidney injury (AKI) is a common clinical disease characterized by rapid loss of renal function. Salvianolate is a prescribed Chinese medicine derived from traditional Chinese medicine Salvia miltiorrhiza bunge that possesses many pharmacological effects, the active components extracted from Salvia miltiorrhiza bunge have been proved to protect ischemia-reperfusion (I/R)-AKI.

AIM OF THE STUDY

This study aims to validate the therapeutic effect of SAL on I/R-AKI, and explore its potential pharmacological mechanism.

MATERIALS AND METHODS

Mice were pretreated with/without salvianolate (10, 30, and 90 mg/kg) before renal ischemia-reperfusion operation. Serum creatinine, BUN, and H&E staining were performed to evaluate renal function. Immunofluorescence analysis was conducted to measure renal tubular injury including inflammatory factors and peroxide level. Apoptosis of the kidney tissues was determined by TUNEL assay. Keap1-Nrf2-ARE and apoptosis signaling pathways were measured by Western blot, RT-PCR, and YO-PRO-1 staining in kidneys or NRK52E cells.

RESULTS

Pretreatment with SAL effectively alleviated renal function and ameliorated epithelial tubular injury, oxidative stress, and inflammatory response. Furthermore, the mechanistic study demonstrated that the SAL exerts anti-apoptotic effects through activation of the Keap1-Nrf2-ARE signaling pathway in renal tubular cells.

CONCLUSION

These findings indicate the therapeutic benefit of salvianolate in the protection of renal injury from ischemia-reperfusion, and strengthen the evidence for the AKI treatment strategy by the anti-oxidative stress response, suggesting that SAL may be a potential agent for the treatment of AKI.

Protection Against Post-resuscitation Acute Kidney Injury by N-Acetylcysteine via Activation of the Nrf2/HO-1 Pathway

Background and Objective

Acute kidney injury (AKI), the common complication after cardiopulmonary resuscitation (CPR), seriously affects the prognosis of cardiac arrest (CA) patients. However, there are limited studies on post-resuscitation AKI. In addition, it has been demonstrated that N-acetylcysteine (N-AC) as an ROS scavenger, has multiorgan-protective effects on systemic and regional ischaemia-reperfusion injuries. However, no studies have reported its protective effects against post-resuscitation AKI and potential mechanisms. This study aimed to clarify the protective effects of N-AC on post-resuscitation AKI and investigate whether its potential mechanism was mediated by activating Nrf-2/HO-1 pathway in the kidney.

Methods

We established cardiac arrest models in rats. All animals were divided into four groups: the sham, control, N-AC, and ZnPP groups. Animals in each group except for the ZnPP group were assigned into two subgroups based on the survival time: 6 and 48 h. The rats in the control, N-AC, and ZnPP groups underwent induction of ventricular fibrillation (VF), 8 min untreated VF and cardiopulmonary resuscitation. Renal function indicators, were detected using commercial kits. Renal pathologic changes were assessed by haematoxylin–eosin (HE) staining. Oxidative stress and inflammatory responses were measured using the corresponding indicators. Apoptosis was evaluated using terminal uridine nick-end labeling (TUNEL) staining, and expression of proteins associated with apoptosis and the Nrf-2/HO-1 pathway was measured by western blotting.

Results

N-AC inhibited post-resuscitation AKI. We observed that N-AC reduced the levels of biomarkers of renal function derangement; improved renal pathological changes; and suppressed apoptosis, oxidative stress, and inflammatory response. Additionally, the production of ROS in the kidneys markedly decreased by N-AC. More importantly, compared with the control group, N-AC further upregulated the expression of nuclear Nrf2 and endogenous HO-1 in N-AC group. However, N-AC-determined protective effects on post-resuscitation AKI were markedly reversed after pretreatment of the HO-1 inhibitor zinc protoporphyrin (ZnPP).

Conclusions

N-AC alleviated renal dysfunction and prolonged survival in animal models of CA. N-AC partially exerts beneficial renal protection via activation of the Nrf-2/HO-1 pathway. Altogether, all these findings indicated that N-AC as a common clinical agent, may have the potentially clinical utility to improve patients the outcomes in cardiac arrest.

Tilianin Reduces Apoptosis via the ERK/EGR1/BCL2L1 Pathway in Ischemia/Reperfusion-Induced Acute Kidney Injury Mice

Background: Acute kidney injury (AKI) is a common syndrome impacting about 13.3 million patients per year. Tilianin has been reported to alleviate myocardial ischemia/reperfusion (I/R) injury, while its effect on AKI is unknown; thus, this study aimed to explore if tilianin protects I/R-induced AKI and the underlying mechanisms.

Methods: The microarray dataset GSE52004 was downloaded from GEO DataSets (Gene Expression Omnibus). Differential expression analysis and gene-set enrichment analysis (GSEA) were performed by R software to identify apoptosis pathway-related genes. Then, RcisTarget was applied to identify the transcription factor (TF) related to apoptosis. The STRING database was used to construct a protein–protein interaction (PPI) network. Cytoscape software visualized PPI networks, and hub TFs were selected via cytoHubba. AutoDock was used for molecular docking of tilianin and hub gene-encoded proteins. The expression levels of hub genes were assayed and visualized by quantitative real-time PCR, Western blotting, and immunohistochemistry by establishing I/R-induced AKI mouse models.

Results: Bioinformatics analysis showed that 34 genes, including FOS, ATF4, and Gadd45g, were involved in the apoptosis pathway. In total, seven hub TFs might play important roles in tilianin-regulating apoptosis pathways. In in vivo, tilianin improved kidney function and reduced the number of TUNEL-positive renal tubular epithelial cells (RTECs) after I/R-induced AKI. Tilianin reduced the activation of the ERK pathway and then downregulated the expression of EGR1. This further ameliorated the expression of anti-apoptotic genes such as BCL2L1 and BCL2, reduced pro-apoptotic genes such as BAD, BAX, and caspase-3, and reduced the release of cytochrome c.

Conclusion: Tilianin reduced apoptosis after I/R-induced AKI by the ERK/EGR1/BCL2L1 pathway. Our findings provided novel insights for the first time into the protective effect and underlying molecular mechanisms of tilianin on I/R-induced AKI.

PLK2 targets GSK3β to protect against cisplatin-induced acute kidney injury

Cisplatin-induced acute kidney injury (AKI), which is accompanied by a rapid decline in renal function and a high risk of death, is a complex critical illness with no effective or specific treatment. Polo-like kinase 2 (PLK2), a serine/threonine kinase, is involved in the progression of multiple diseases, including cancers, cardiac fibrosis, diabetic nephropathy, etc. Here, by integrating two Gene Expression Omnibus (GEO) datasets of cisplatin-induced AKI animal models, we identified PLK2 as a significantly up-regulated gene in AKI renal tissues, which was then verified in different AKI animal models and cell models. Suppressing PLK2 using siRNAs or inhibitors could enhance cisplatin-induced AKI by inducing severe apoptosis and oxidative stress damage, while enforced PLK2 expression could prevent renal dysfunction induced by cisplatin. We further discovered that PLK2 might phosphorylate glycogen synthase kinase 3β (GSK3β) in the pathogenesis of AKI. In conclusion, our results show that PLK2 play a protective role in cisplatin-induced AKI and may be a new protective target of cisplatin nephrotoxicity.

Nrf2 and NF-κB/NLRP3 inflammasome pathways are involved in Prototheca bovis infections of mouse mammary gland tissue and mammary epithelial cells

Prototheca bovis is a serious pathogen for animals, but pathogenesis of P. bovis mastitis is unclear. The objective was to characterize how P. bovis induces inflammatory responses in mouse mammary gland tissue and mammary epithelial cells (mMECs). Prototheca bovis damaged mammary gland tissue and mitochondrial structure, and induced oxidative stress, as evident by significant increases in mtROS and MDA concentrations and significant decreases in T-SOD activity in both mammary gland tissue and mMECs. Expression of Nrf2, HO-1 and Keap1 proteins was significantly changed in mammary gland tissue and mMECs after P. bovis infection. Additionally, cytokines (IL-1β, IL-6 and IL-18) and protein expressions in NF-κB and in the NLRP3 inflammasome pathway were significantly increased in mammary gland tissue and mMECs. In the P. bovis group, treatment with N-acetyl-l-cysteine (NAC) significantly decreased protein expression in NF-κB and the NLRP3 inflammasome pathway, as well as IL-1β, IL-6 and IL-18, whereas protein expression in the Nrf2 pathway was significantly changed. Inhibition of NF-κB or NLRP3 significantly decreased expression of IL-1β and IL-18 proteins in mMECs infected with P. bovis. Additionally, activating Nrf2 inhibited expression of NLRP3 and IL-1β. In conclusion, P. bovis induced an inflammatory response via the NF-κB/NLRP3 inflammasome pathway; however, scavenging ROS or activating Nrf2 mitigated the inflammatory response in infected mMECs.

Persistent activation of Nrf2 in a p62-dependent non-canonical manner aggravates lead-induced kidney injury by promoting apoptosis and inhibiting autophagy

INTRODUCTION

Lead (Pb) is an environmental toxicant that poses severe health risks to humans and animals, especially renal disorders. Pb-induced nephrotoxicity has been attributed to oxidative stress, in which apoptosis and autophagy are core events.

OBJECTIVES

Nuclear factor erythroid 2-related factor 2 (Nrf2) acts as a major contributor to counteract oxidative damage, while hyperactivation or depletion of Nrf2 pathway can cause the redox imbalance to induce tissue injury. This study was performed to clarify the function and mechanism of Nrf2 in Pb-triggered kidney injury.

METHODS AND RESULTS

First, data showed that Pb exposure activates Nrf2 pathway in primary rat proximal tubular cells. Next, Pb-induced Nrf2 activation was effectively regulated by pharmacological modulation or siRNA-mediated knockdown in vitro and in vivo assays. Notably, Pb-triggered cytotoxicity, renal injury and concomitant apoptosis were improved by Nrf2 downregulation, confirming that Pb-induced persistent Nrf2 activation contributes to nephrotoxicity. Additionally, Pb-triggered autophagy blockage was relieved by Nrf2 downregulation. Mechanistically, we found that Pb-induced persistent Nrf2 activation is attributed to reduced Nrf2 ubiquitination and nuclear-cytoplasmic loss of Keap1 in a p62-dependent manner.

CONCLUSIONS

In conclusion, these findings highlight the dark side of persistent Nrf2 activation and potential crosstalk among Pb-induced persistent Nrf2 activation, apoptosis and autophagy blockage in Pb-triggered nephrotoxicity.

Regulation of Mitochondrial Homeostasis and Nrf2 in Kidney Disease: Timing Is Critical

Abnormal regulation of mitochondrial homeostasis plays a critical role in the progression of renal disease. Recent studies have shown that activation of nuclear factor erythroid 2-related factor 2 (Nrf2) has time-dependent protective effects, which can be explained by the differing regulation of mitochondrial homeostasis during the various stages of kidney disease. In this review, we summarize the mechanisms whereby mitochondrial homeostasis is regulated and the nature of the dysregulation of mitochondrial homeostasis in renal disease. In addition, we summarize the dual roles of Nrf2 in kidney disease by discussing the studies that have shown the importance of the timing of its activation in the regulation of mitochondrial homeostasis. This should provide a theoretical basis for therapeutic strategies aimed at activating Nrf2 in kidney disease.

Signaling pathways and targeted therapy for myocardial infarction

Although the treatment of myocardial infarction (MI) has improved considerably, it is still a worldwide disease with high morbidity and high mortality. Whilst there is still a long way to go for discovering ideal treatments, therapeutic strategies committed to cardioprotection and cardiac repair following cardiac ischemia are emerging. Evidence of pathological characteristics in MI illustrates cell signaling pathways that participate in the survival, proliferation, apoptosis, autophagy of cardiomyocytes, endothelial cells, fibroblasts, monocytes, and stem cells. These signaling pathways include the key players in inflammation response, e.g., NLRP3/caspase-1 and TLR4/MyD88/NF-κB; the crucial mediators in oxidative stress and apoptosis, for instance, Notch, Hippo/YAP, RhoA/ROCK, Nrf2/HO-1, and Sonic hedgehog; the controller of myocardial fibrosis such as TGF-β/SMADs and Wnt/β-catenin; and the main regulator of angiogenesis, PI3K/Akt, MAPK, JAK/STAT, Sonic hedgehog, etc. Since signaling pathways play an important role in administering the process of MI, aiming at targeting these aberrant signaling pathways and improving the pathological manifestations in MI is indispensable and promising. Hence, drug therapy, gene therapy, protein therapy, cell therapy, and exosome therapy have been emerging and are known as novel therapies. In this review, we summarize the therapeutic strategies for MI by regulating these associated pathways, which contribute to inhibiting cardiomyocytes death, attenuating inflammation, enhancing angiogenesis, etc. so as to repair and re-functionalize damaged hearts.

Therapeutic potential of mangiferin against kidney disorders and its mechanism of action: A review

There is a swing in research developments concerning the utilization of natural products as effective pharmacotherapeutic agents due to their comparatively lower toxicities than synthetic compounds. Among natural products, mangiferin is a natural C-glucosyl xanthonoid polyphenol with remarkable pharmacological activities. Emerging evidence indicates the therapeutic benefits of mangiferin against various kidney disorders, including renal injury, diabetic nephropathy, renal fibrosis, hyperuricemic nephropathy, and lupus nephritis, in experimental animal models. The mangiferin induced antioxidant response resulting in vital functions, such as protection against renal inflammation, inhibits renal cell apoptosis, activates autophagy, causes immunomodulation, regulates renal urate transporters and modulates cell signalling pathways. The purpose of this review provide a brief overview of the in vitro/in vivo reno-protective effect of mangiferin and the underlying mechanism(s) in protecting against kidney disorders. Understanding the pharmacological actions of mangiferin is prominence due to its excellent therapeutic potential in managing kidney disorders. Thus, in addition to this review, in-silico molecular docking is performed against nuclear factor kappa B (NF-κB) and soluble epoxide hydrolase (sEH) to study the mechanism of action of mangiferin. It is believed that mangiferin is a safe reno-protective molecule. The observed positive effects are attributed to the inhibition of inflammation caused by NF-κB and sEH upregulation and oxidative stress activation. Studies on the efficacy and safety of mangiferin in clinical trials are further warranted to confirm its medicinal potential as therapeutic agent for kidney disorders in humans.

Identification of inflammatory response and alternative splicing in acute kidney injury and experimental verification of the involvement of RNA‑binding protein RBFOX1 in this disease

An increasing number of inflammatory responses and alternative splicing (AS) have been recently reported to be associated with various kidney diseases. The effect of inflammatory response on acute kidney injury (AKI) has not been fully clarified. In the present study, a mouse model of AKI induced by cisplatin and ischemia-reperfusion (IR) was established and genome-wide profiling analysis and identification of differentially expressed genes (DEGs) in kidney tissue was conducted by Gene Ontology (GO) functional analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, protein-protein interaction (PPI) network analysis and RT-qPCR. The results revealed that common DEGs in AKI induced by cisplatin and IR were enriched in the inflammatory response pathway, including hub genes CSF-1, CXCL1, CXCL10, IL-1β, IL-34, IL-6 and TLR2. AS in AKI was initially reported. Cisplatin-induced AS was enriched in the phosphorylation pathway, involving regulated AS genes CSNK1A1, PAK2, CRK, ADK and IKBKB. IR-induced AS was enriched in apoptosis and proliferation pathways, including DEGs ZDHHC16, BCL2L1 and FGF1 regulated by AS. The ability of RNA-binding proteins (RBPs) to regulate AS was coordinated with the function of context-dependent genetic mechanisms. A total of 49 common differentially expressed RBP genes were screened. RNA binding fox-1 homolog 1 (RBFOX1) was revealed to be the top downregulated gene. The relative levels of RBFOX1 in the nuclei of mouse renal tubular epithelial cells in mRNA and proteins were downregulated by cisplatin and IR. Moreover, the biological functions of RBFOX1 were investigated in human renal proximal tubular epithelial cells (HK-2 cells). Results of in vitro experiments revealed that exogenous RBFOX1 inhibited inflammation and oxidative stress to reduce hypoxia/reoxygenation-induced apoptosis of HK-2 cells. This phenomenon may be related to the inhibition of NF-κB and the activation of the NRF2/HO-1 signaling pathway. In conclusion, the inflammatory cytokines, AS and RBPs in AKI were analyzed in the present study via whole transcriptome sequencing. It was revealed that the RBP gene RBFOX1 was involved in the pathogenesis of AKI. Thus, the present study provided novel insights into the mechanism of AKI pathogenesis.

Nrf2-Related Therapeutic Effects of Curcumin in Different Disorders

Curcumin is a natural polyphenol with antioxidant, antibacterial, anti-cancer, and anti-inflammation effects. This substance has been shown to affect the activity of Nrf2 signaling, a pathway that is activated in response to stress and decreases levels of reactive oxygen species and electrophilic substances. Nrf2-related effects of curcumin have been investigated in different contexts, including gastrointestinal disorders, ischemia-reperfusion injury, diabetes mellitus, nervous system diseases, renal diseases, pulmonary diseases, cardiovascular diseases as well as cancers. In the current review, we discuss the Nrf2-mediated therapeutic effects of curcumin in these conditions. The data reviewed in the current manuscript indicates curcumin as a potential activator of Nrf2 and a therapeutic substance for the protection of cells in several pathological conditions.

Farrerol Ameliorated Cisplatin-Induced Chronic Kidney Disease Through Mitophagy Induction via Nrf2/PINK1 Pathway

Previously, Our study has showed that farrerol can activate Nrf2 and ameliorate cisplatin-induced acute kidney injury (AKI). Mitophagy reportedly can prevent diabetic nephropathy, cisplatin-induced AKI and other related nephropathy. In this study, we evaluated the correlation between mitophagy and the protective effect of the Nrf2 activator farrerol on cisplatin-induced CKD by using C57BL/6 wild-type and Nrf2 knockout mice. We confirmed that Nrf2 and PINK1/Parkin-mediated mitophagy was significantly increased on the 3rd day of cisplatin stimulation but was reduced on the 38th day of cisplatin stimulation. Similar to previous results, farrerol activated Nrf2 on the 38th day of cisplatin administration, subsequently stimulating the Nrf2-targeted antioxidant enzymes HO-1 and NQO1. In addition, farrerol triggered PINK1/Parkin-mediated mitophagy by recruiting the receptor proteins LC3 and p62/SQSTM1, thereby eliminating damaged mitochondria. Furthermore, genetic deletion of Nrf2 reduced PINK1/Parkin-mediated mitophagy activation and led to increased renal tubular necrosis and renal fibrosis. We also found that farrerol alleviated inflammation and renal fibrosis by inhibiting p-NF-κB/NLRP3 and TGF-β/Smad signaling. These data indicated that farrerol effectively inhibited cisplatin-induced inflammation and renal fibrosis by activating Nrf2 and PINK1/Parkin-mediated mitophagy, which provides a potential novel therapeutic target for CKD.

Extracellular vesicles derived from mesenchymal stem cells as a potential therapeutic agent in acute kidney injury (AKI) in felines: review and perspectives

Mesenchymal stem cells (MSCs), known from their key role in the regeneration process of tissues, and their abilities to release bioactive factors like extracellular vesicles (EVs) could be considered as a potential, modern tool in the treatment of AKI (acute kidney injury) in both human and veterinary patients. The complex pathophysiology of a renal function disorder (AKI) makes difficult to find a universal therapy, but the treatment strategy is based on MSCs and derived from them, EVs seem to solve this problem. Due to their small size, the ability of the cargo transport, the ease of crossing the barriers and the lack of the ability to proliferate and differentiate, EVs seem to have a significant impact on the development such therapy. Their additional impact associated with their ability to modulate immune response and inflammation process, their strong anti-fibrotic and anti-apoptotic effects and the relation with the releasing of the reactive oxygen species (ROS), that pivotal role in the AKI development is undoubtedly, limits the progress of AKI. Moreover, the availability of EVs from different sources encourages to extend research with using EVs from MSCs in AKI treatment in felines; in that, the possibilities of kidney injuries treatment are still limited to the classical therapies burdened with dangerous side effects. In this review, we underline the significance of the processes, in whose EVs are included during the AKI in order to show the potential benefits of EVs-MSCs-based therapies against AKI in felines.

Chemical Constituents from the Rhizome of Ligusticum chuanxiong Hort. and Their Nrf2 Inducing Activity

The rhizome of Ligusticum chuanxiong Hort. has been widely used for the therapy of diabetic nephropathy (DN) in traditional Chinese medicine (TCM). The nuclear transcription factor erythroid 2-related factor (Nrf2) is a potential target for treating DN. The purpose of this research was to study the chemical constituents from the rhizome of L. chuanxiong, evaluate their Nrf2 inducing activity, and find the molecules with potential therapeutic effect against DN. In this study, two new phthalides (1-2) along with twenty-seven known constituents were obtained from the rhizome of L. chuanxiong. Their structures were elucidated through various spectroscopic methods. Twelve constituents, including eight phthalides (2, 5, 6,10-13, 14) and four other compounds (17, 18, 20,28), stimulated NAD(P)H: quinone reductase (QR) activity, suggesting that these bioactive constituents were potential Nrf2 activators. Among the isolated compounds, phthalide levistolide A (LA, 14) upregulated the protein levels of Nrf2, NQO1, and γ-GCS in a dose-dependent manner. Our results implied that the clinical application of the rhizome of L. chuanxiong as an anti-DN drug in TCM might be attributed to the Nrf2 inducing effect of phthalides. Thus, phthalides is a group of promising leading molecules for discovering anti-DN agents.

Redox-sensitive Nrf2 and MAPK signaling pathways contribute to trichloroethene-mediated autoimmune disease progression

Trichloroethene (TCE) exposure is associated with the induction of autoimmune diseases (ADs). Although oxidative stress plays a major role in TCE-mediated autoimmunity, the underlying molecular mechanisms still need to be delineated. Dysregulation of redox-sensitive nuclear factor (erythroid-derived 2)-like2 (Nrf2), resulting in uncontrolled antioxidant and cytoprotective genes, and pro-inflammatory MAPK signaling pathways could be critical in TCE-mediated disease progression. This study was, therefore, focused on establishing status and contribution of Nrf2 and MAPK signaling in TCE-mediated inflammatory and autoimmune responses, especially during disease progression. To achieve these objectives, time-response studies were conducted by treating female MRL+/+ mice with TCE (0.5 mg/mL, a dose relevant to human exposure) for 24, 36 and 52 wks. TCE exposure led to reduction in Nrf2 expression, but increased phos-NF-κB (p65) and iNOS along with increased phosphorylation of MAPKs (p38, ERK and JNK) and downstream pro-inflammatory cytokines IL-12, TNF-α and RANTES in the livers in a time-dependent manner. These changes were also associated with time-dependent increases in liver protein carbonyls and induction of serum anti-dsDNA antibodies (marker of systemic lupus erythematosus disease), further supporting the role of oxidative stress and Nrf2/MAPK signaling in TCE-mediated autoimmune response progression. The mechanistic role of MAPK in TCE-mediated autoimmunity was further established by treating MRL+/+ mice with sulforaphane (SFN; 8 mg/kg, i.p., every other day) along with TCE (10 mmol/kg, i.p., every 4th day) for 6 wks using an established protocol, and by in vitro treatment of T cells with dichloroacetyl chloride (a TCE metabolite) with/without p38 MAPK inhibitor. SFN treatment attenuated the TCE-mediated phosphorylation of p38 MAPK. More importantly, treatment with SFN or p38 inhibitor led to suppression of downstream pro-inflammatory cytokines IL-12 and TNF-α. These findings thus support the contribution of Nrf2 and MAPK signaling pathways and help in delineating novel potential therapeutic targets against TCE-mediated autoimmunity.

Up-regulation of CTRP12 ameliorates hypoxia/re-oxygenation-induced cardiomyocyte injury by inhibiting apoptosis, oxidative stress, and inflammation via the enhancement of Nrf2 signaling

C1q/TNF-related protein 12 (CTRP12) has been reported to play a key role in coronary artery disease. However, whether CTRP12 plays a role in the regulation of myocardial ischemia-reperfusion injury is not fully understood. The goals of this work were to assess the possible relationship between CTRP12 and myocardial ischemia-reperfusion injury. Here, we exposed cardiomyocytes to hypoxia/re-oxygenation (H/R) to establish an in vitro cardiomyocyte injury model of myocardial ischemia-reperfusion injury. Our results showed that H/R treatment resulted in a decrease in CTRP12 expression in cardiomyocytes. The up-regulation of CTRP12 ameliorated H/R-induced cardiomyocyte injury via the down-regulation of apoptosis, oxidative stress, and inflammation. In contrast, the knockdown of CTRP12 enhanced cardiomyocyte sensitivity to H/R-induced cardiomyocyte injury. Further investigation showed that CTRP12 enhanced the levels of nuclear Nrf2 and increased the expression of Nrf2 target genes in cardiomyocytes exposed to H/R. However, the inhibition of Nrf2 markedly diminished CTRP12-overexpression-mediated cardioprotective effects against H/R injury. Overall, these data indicate that CTRP12 protects against H/R-induced cardiomyocyte injury by inhibiting apoptosis, oxidative stress, and inflammation via the enhancement of Nrf2 signaling. This work suggests a potential role of CTRP12 in myocardial ischemia-reperfusion injury and proposes it as an attractive target for cardioprotection.

Recombinant Long-Acting Thioredoxin Ameliorates AKI to CKD Transition via Modulating Renal Oxidative Stress and Inflammation

An effective strategy is highly desirable for preventing acute kidney injury (AKI) to chronic kidney disease (CKD) transition. Thioredoxin-1 (Trx), a redox-active protein that has anti-oxidative and anti-inflammatory properties, would be a candidate for this but its short half-life limits its clinical application. In this study, we examined the renoprotective effect of long-acting Trx that is comprised of human albumin and Trx (HSA-Trx) against AKI to CKD transition. AKI to CKD mice were created by renal ischemia-reperfusion (IR). From day 1 to day 14 after renal IR, the recovery of renal function was accelerated by HSA-Trx administration. On day 14, HSA-Trx reduced renal fibrosis compared with PBS treatment. At the early phase of fibrogenesis (day 7), HSA-Trx treatment suppressed renal oxidative stress, pro-inflammatory cytokine production and macrophage infiltration, thus ameliorating tubular injury and fibrosis. In addition, HSA-Trx treatment inhibited G2/M cell cycle arrest and apoptosis in renal tubular cells. While renal Trx protein levels were decreased after renal IR, the levels were recovered by HSA-Trx treatment. Together, HSA-Trx has potential for use in the treatment of AKI to CKD transition via its effects of modulating oxidative stress and inflammation.

Hyaluronic acid coated bilirubin nanoparticles attenuate ischemia reperfusion-induced acute kidney injury

Acute kidney injury (AKI) is a common pathological process that is globally associated with a high morbidity and mortality rate. The underlying AKI mechanisms include over-produced reactive oxygen species (ROS), inflammatory cell infiltration, and high levels of inflammatory mediators. Bilirubin is an endogenous compound with antioxidant, anti-inflammatory and anti-apoptotic properties, and could, therefore, be a promising therapeutic candidate. Nanotechnology-mediated therapy has emerged as a novel drug delivery strategy for AKI treatment. In this study, we report a hyaluronic acid (HA) coated ε-polylysine-bilirubin conjugate (PLBR) nanoparticle (nHA/PLBR) that can selectively accumulate in injured kidneys and alleviate the oxidative/inflammatory-induced damage. The in vitro study revealed that nHA/PLBR has good stability, biocompatibility, and exhibited higher antioxidant as well as anti-apoptotic effects when compared to nPLBR or bilirubin. The in vivo study showed that nHA/PLBR could target and accumulate in the injured kidney, effectively relieve oxidative stress and inflammatory reactions, protect the structure and function of the mitochondria, and more importantly, inhibit the apoptosis of tubular cells in an ischemia/reperfusion-induced AKI rat model. Therefore, nHA/PLBR has the capacity to enhance specific biodistribution and delivery efficiency of bilirubin, thereby providing better treatment for AKI in the future.

Anti-Viral Potential and Modulation of Nrf2 by Curcumin: Pharmacological Implications

Nuclear factor erythroid 2-related factor 2 (Nrf2) is an essential transcription factor that maintains the cell's redox balance state and reduces inflammation in different adverse stresses. Under the oxidative stress, Nrf2 is separated from Kelch-like ECH-associated protein 1 (Keap1), which is a key sensor of oxidative stress, translocated to the nucleus, interacts with the antioxidant response element (ARE) in the target gene, and then activates the transcriptional pathway to ameliorate the cellular redox condition. Curcumin is a yellow polyphenolic curcuminoid from Curcuma longa (turmeric) that has revealed a broad spectrum of bioactivities, including antioxidant, anti-inflammatory, anti-tumor, and anti-viral activities. Curcumin significantly increases the nuclear expression levels and promotes the biological effects of Nrf2 via the interaction with Cys151 in Keap1, which makes it a marvelous therapeutic candidate against a broad range of oxidative stress-related diseases, including type 2 diabetes (T2D), neurodegenerative diseases (NDs), cardiovascular diseases (CVDs), cancers, viral infections, and more recently SARS-CoV-2. Currently, the multifactorial property of the diseases and lack of adequate medical treatment, especially in viral diseases, result in developing new strategies to finding potential drugs. Curcumin potentially opens up new views as possible Nrf2 activator. However, its low bioavailability that is due to low solubility and low stability in the physiological conditions is a significant challenge in the field of its efficient and effective utilization in medicinal purposes. In this review, we summarized recent studies on the potential effect of curcumin to activate Nrf2 as the design of potential drugs for a viral infection like SARS-Cov2 and acute and chronic inflammation diseases in order to improve the cells' protection.