Protective effect of glycyrrhizin, a direct HMGB1 inhibitor, on post-contrast acute kidney injury

Glycyrrhizin attenuates renal inflammation in a mouse Con A-hepatitis model via the IL-25/M2 axis

Glycyrrhizin (GL) has immunoregulatory effects on various inflammatory diseases including hepatitis and nephritis. However, the mechanisms underlying the anti-inflammatory effect of GL on renal inflammation are not fully understood. Hepatorenal syndrome (HRS) is a functional acute renal impairment that occurs in severe liver disease, and we found that kidney injury also occurs in Con A-induced experimental hepatitis in mice. We previously found that GL can alleviate Con A-induced hepatitis by regulating the expression of IL-25 in the liver. We wanted to investigate whether GL can alleviate Con A-induced nephritis by regulating IL-25. IL-25 regulates inflammation by modulating type 2 immune responses, but the mechanism by which IL-25 affects kidney disease remains unclear. In this study, we found that the administration of GL enhanced the expression of IL-25 in renal tissues; the latter promoted the generation of type 2 macrophages (M2), which inhibited inflammation in the kidney caused by Con A challenge. IL-25 promoted the secretion of the inhibitory cytokine IL-10 by macrophages but inhibited the expression of the inflammatory cytokine IL-1β by macrophages. Moreover, IL-25 downregulated the Con A-mediated expression of Toll-like receptor (TLR) 4 on macrophages. By comparing the roles of TLR2 and TLR4, we found that TLR4 is required for the immunoregulatory effect of IL-25 on macrophages. Our data revealed that GL has anti-inflammatory effects on Con A-induced kidney injury and that the GL/IL-25/M2 axis participates in the anti-inflammatory process. This study suggested that GL is a potential therapeutic for protecting against acute kidney injury.

Renal Health Through Medicine-Food Homology: A Comprehensive Review of Botanical Micronutrients and Their Mechanisms

BACKGROUND

As an ancient concept and practice, "food as medicine" or "medicine-food homology" is receiving more and more attention these days. It is a tradition in many regions to intake medicinal herbal food for potential health benefits to various organs and systems including the kidney. Kidney diseases usually lack targeted therapy and face irreversible loss of function, leading to dialysis dependence. As the most important organ for endogenous metabolite and exogenous nutrient excretion, the status of the kidney could be closely related to daily diet. Therefore, medicinal herbal food rich in antioxidative, anti-inflammation micronutrients are ideal supplements for kidney protection. Recent studies have also discovered its impact on the "gut-kidney" axis.

METHODS

Here, we review and highlight the kidney-protective effects of botanicals with medicine-food homology including the most frequently used Astragalus membranaceus and Angelica sinensis (Oliv.) Diels, concerning their micronutrients and mechanism, offering a basis and perspective for utilizing and exploring the key substances in medicinal herbal food to protect the kidney.

RESULTS

The index for medicine-food homology in China contains mostly botanicals while many of them are also consumed by people in other regions. Micronutrients including flavonoids, polysaccharides and others present powerful activities towards renal diseases.

CONCLUSIONS

Botanicals with medicine-food homology are widely speeded over multiple regions and incorporating these natural compounds into dietary habits or as supplements shows promising future for renal health.

Macrophages-derived high-mobility group box-1 protein induces endothelial progenitor cells pyroptosis

Endothelial dysfunction is an important factor in the progress of sepsis. Endothelial progenitor cells (EPCs) are the precursor cells of endothelial cells and play a crucial role in the prognosis and treatment of sepsis. EPCs in the peripheral blood of patients with sepsis undergo pyroptosis, but the mechanism remains much of unknown. Serum high-mobility group box-1 (HMGB1) is significantly elevated in patients with sepsis, but whether it is related to EPCs pyroptosis is unknown. We used a cell model of sepsis in vitro to isolate EPCs for better observation. By detecting the pyroptosis-related indicators of EPCs and the level of release and acetylation of HMGB1 in inflammatory macrophages, it was found that HMGB1 released by inflammatory macrophages combined with receptor for advanced glycation end products (RAGE) is a key pathway to induce pyroptosis of EPCs.

HMGB1 as an extracellular pro-inflammatory cytokine: Implications for drug-induced organic damage

Drug-induced organic damage encompasses various intricate mechanisms, wherein HMGB1, a non-histone chromosome-binding protein, assumes a significant role as a pivotal hub gene. The regulatory functions of HMGB1 within the nucleus and extracellular milieu are interlinked. HMGB1 exerts a crucial regulatory influence on key biological processes including cell survival, inflammatory regulation, and immune response. HMGB1 can be released extracellularly from the cell during these processes, where it functions as a pro-inflammation cytokine. HMGB1 interacts with multiple cell membrane receptors, primarily Toll-like receptors (TLRs) and receptor for advanced glycation end products (RAGE), to stimulate immune cells and trigger inflammatory response. The excessive or uncontrolled HMGB1 release leads to heightened inflammatory responses and cellular demise, instigating inflammatory damage or exacerbating inflammation and cellular demise in different diseases. Therefore, a thorough review on the significance of HMGB1 in drug-induced organic damage is highly important for the advancement of pharmaceuticals, ensuring their effectiveness and safety in treating inflammation as well as immune-related diseases. In this review, we initially outline the characteristics and functions of HMGB1, emphasizing their relevance in disease pathology. Then, we comprehensively summarize the prospect of HMGB1 as a promising therapeutic target for treating drug-induced toxicity. Lastly, we discuss major challenges and propose potential avenues for advancing the development of HMGB1-based therapeutics.

High-mobility group box 1 and its related receptors: potential therapeutic targets for contrast-induced acute kidney injury

Percutaneous coronary intervention (PCI) is a crucial diagnostic and therapeutic approach for coronary heart disease. Contrast agents' exposure during PCI is associated with a risk of contrast-induced acute kidney injury (CI-AKI). CI-AKI is characterized by a sudden decline in renal function occurring as a result of exposure to intravascular contrast agents, which is associated with an increased risk of poor prognosis. The pathophysiological mechanisms underlying CI-AKI involve renal medullary hypoxia, direct cytotoxic effects, endoplasmic reticulum stress, inflammation, oxidative stress, and apoptosis. To date, there is no effective therapy for CI-AKI. High-mobility group box 1 (HMGB1), as a damage-associated molecular pattern molecule, is released extracellularly by damaged cells or activated immune cells and binds to related receptors, including toll-like receptors and receptor for advanced glycation end product. In renal injury, HMGB1 is expressed in renal tubular epithelial cells, macrophages, endothelial cells, and glomerular cells, involved in the pathogenesis of various kidney diseases by activating its receptors. Therefore, this review provides a theoretical basis for HMGB1 as a therapeutic intervention target for CI-AKI.

Safety of Administering Intravenous CT Contrast Agents Repeatedly or Using Both CT and MRI Contrast Agents on the Same Day: An Animal Study

OBJECTIVE

To investigate molecular and functional consequences of additional exposures to iodine- or gadolinium-based contrast agents within 24 hours from the initial intravenous administration of iodine-based contrast agents through an animal study.

MATERIALS AND METHODS

Fifty-six Sprague-Dawley male rats were equally divided into eight groups: negative control, positive control (PC) with single-dose administration of CT contrast agent, and additional administration of either CT or MR contrast agents 2, 4, or 24 hours from initial CT contrast agent injection. A 12 µL/g of iodinated contrast agent or a 0.47 µL/g of gadolinium-based contrast agent were injected into the tail vein. Serum levels of blood urea nitrogen, creatinine, cystatin C (Cys C), and malondialdehyde (MDA) were measured. mRNA and protein levels of kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) were evaluated.

RESULTS

Levels of serum creatinine (SCr) were significantly higher in repeated CT contrast agent injection groups than in PC (0.21 ± 0.02 mg/dL for PC; 0.40 ± 0.02, 0.34 ± 0.03, and 0.41 ± 0.10 mg/dL for 2-, 4-, and 24-hour interval groups, respectively; P < 0.001). There was no significant difference in the average Cys C and MDA levels between PC and repeated CT contrast agent injection groups (Cys C, P = 0.256-0.362; MDA, P > 0.99). Additional doses of MR contrast agent did not make significant changes compared to PC in SCr (P > 0.99), Cys C (P = 0.262), and MDA (P = 0.139-0.771) levels. mRNA and protein levels of KIM-1 and NGAL were not significantly different among additional CT or MR contrast agent groups (P > 0.05).

CONCLUSION

A sufficient time interval, probably more than 24 hours, between repeated contrast-enhanced CT examinations may be necessary to avoid deterioration in renal function. However, conducting contrast-enhanced MRI on the same day as contrast-enhanced CT may not induce clinically significant kidney injury.

The Role of mTOR in Doxorubicin-Altered Cardiac Metabolism: A Promising Therapeutic Target of Natural Compounds

Doxorubicin (DOX) is commonly used for the treatment of various types of cancer, however can cause serious side effects, including cardiotoxicity. The mechanisms involved in DOX-induced cardiac damage are complex and not yet fully understood. One mechanism is the disruption of cardiac metabolism, which can impair cardiac function. The mammalian target of rapamycin (mTOR) is a key regulator of cardiac energy metabolism, and dysregulation of mTOR signaling has been implicated in DOX-induced cardiac dysfunction. Natural compounds (NCs) have been shown to improve cardiac function in vivo and in vitro models of DOX-induced cardiotoxicity. This review article explores the protective effects of NCs against DOX-induced cardiac injury, with a focus on their regulation of mTOR signaling pathways. Generally, the modulation of mTOR signaling by NCs represents a promising strategy for decreasing the cardiotoxic effects of DOX.

HMGB1 neuroimmune signaling and REST-G9a gene repression contribute to ethanol-induced reversible suppression of the cholinergic neuron phenotype

Adolescent binge drinking increases Toll-like receptor 4 (TLR4), receptor for advanced glycation end products (RAGE), the endogenous TLR4/RAGE agonist high-mobility group box 1 (HMGB1), and proinflammatory neuroimmune signaling in the adult basal forebrain in association with persistent reductions of basal forebrain cholinergic neurons (BFCNs). In vivo preclinical adolescent intermittent ethanol (AIE) studies find anti-inflammatory interventions post-AIE reverse HMGB1-TLR4/RAGE neuroimmune signaling and loss of BFCNs in adulthood, suggesting proinflammatory signaling causes epigenetic repression of the cholinergic neuron phenotype. Reversible loss of BFCN phenotype in vivo is linked to increased repressive histone 3 lysine 9 dimethylation (H3K9me2) occupancy at cholinergic gene promoters, and HMGB1-TLR4/RAGE proinflammatory signaling is linked to epigenetic repression of the cholinergic phenotype. Using an ex vivo basal forebrain slice culture (FSC) model, we report EtOH recapitulates the in vivo AIE-induced loss of ChAT+IR BFCNs, somal shrinkage of the remaining ChAT+ neurons, and reduction of BFCN phenotype genes. Targeted inhibition of EtOH-induced proinflammatory HMGB1 blocked ChAT+IR loss while disulfide HMBG1-TLR4 and fully reduced HMGB1-RAGE signaling decreased ChAT+IR BFCNs. EtOH increased expression of the transcriptional repressor RE1-silencing transcription factor (REST) and the H3K9 methyltransferase G9a that was accompanied by increased repressive H3K9me2 and REST occupancy at promoter regions of the BFCN phenotype genes Chat and Trka as well as the lineage transcription factor Lhx8. REST expression was similarly increased in the post-mortem human basal forebrain of individuals with alcohol use disorder, which is negatively correlated with ChAT expression. Administration of REST siRNA and the G9a inhibitor UNC0642 blocked and reversed the EtOH-induced loss of ChAT+IR BFCNs, directly linking REST-G9a transcriptional repression to suppression of the cholinergic neuron phenotype. These data suggest that EtOH induces a novel neuroplastic process involving neuroimmune signaling and transcriptional epigenetic gene repression resulting in the reversible suppression of the cholinergic neuron phenotype.

Geniposide ameliorates acute kidney injury via enhancing the phagocytic ability of macrophages towards neutrophil extracellular traps

Acute kidney injury (AKI) is a clinically serious disorder associated with high mortality rates and an increased risk of progression to end-stage renal disease. As an essential supportive treatment for patients with respiratory failure, mechanical ventilation not only save many critically ill patients, but also affect glomerular filtration function by changing renal hemodynamics, neurohumoral and positive end-expiratory pressure, eventually leading to AKI. AMP-activated protein kinase (AMPK), a crucial energy homeostasis regulator, could enhance macrophage phagocytic ability and inhibit inflammation, but whether it can engulf neutrophil extracellular traps (NETs) and alleviate mechanical ventilation-associated AKI is still unclear. In this study, we found that geniposide significantly ameliorated histopathological damage, reduced serum Cre and BUN levels. Besides, geniposide can also induce AMPK activation and enhance macrophage phagocytic ability toward NETs. Moreover, geniposide can markedly reduce the levels of high mobility group box 1 (HMGB1), and these effects were dependent on AMPK-PI3K/Akt signaling. Altogether, these results indicated that geniposide promoted macrophage efferocytosis by inducing AMPK-PI3K/Akt signaling activation, clearing NETs and ameliorating AKI.

Delivery of recombinant sestrin2 ameliorates oxidative stress, mitochondrial damage and renal dysfunction in contrast-induced acute kidney injury

Although the use of iodinated contrast agents is sometimes unavoidable for accurate diagnosis, contrast-induced acute kidney injury (CI-AKI) is a possible complication of its administration. The pathogenesis of CI-AKI has not been fully elucidated, but oxidative stress is thought to be a major factor. Sestrin2 plays an important role in cellular and mitochondrial homeostasis by regulating oxidative stress. In this study, we aimed to investigate whether recombinant adenovirus containing sestrin2 (RS) can attenuate CI-AKI by reducing oxidative stress in a CI-AKI mice model. Our results showed that RS decreases oxidative stress, pro-inflammatory cytokines (TNF-α, IL-1α, IL-1β and IL-6) and apoptosis (Bax/Bcl2 and cleaved caspase-3) in the CI-AKI model. Additionally, RS alleviated mitochondrial damage, as evidenced by morphological changes, are restored ATP synthesis. Furthermore, RS administration resulted in a decrease in mitochondrial fission marker (Drp1) that was increased in the CI-AKI model, while the mitochondrial fusion marker (Mfn2) increased, indicating a restoration of mitochondrial dynamics. Decreased relative blood volume, as evaluated on computed tomography (CT), significantly increased compared to the CI-AKI group after RS administration. Finally, renal injury markers such as Kim-1, Ngal, IL-18 also decreased and kidney function was preserved with RS. These results suggested that RS can mitigate the deterioration of renal function in CI-AKI model.

Cadmium induced time-dependent kidney injury in common carp via mitochondrial pathway: Impaired mitochondrial energy metabolism and mitochondrion-dependent apoptosis

Toxic effect of heavy metal cadmium (Cd) on fish kidneys had been reported. Mitochondrion is an important organelle for maintaining kidney function, while its role in Cd-induced kidney injury in common carp remained unclarified. In this experiment, we established a poisoning model of common carp with Cd exposure (0.26 mg/L) for 15, 30, and 45 days. Serum biochemistry determination, histological observation, TUNEL assay, qRT-PCR, Western blot, and integrated biomarker response (IBR) were applied to assess the nephrotoxicity of Cd to common carp. Our results displayed that Cd exposure increased the levels of serum biochemical indexes (UREA, CRE, and UA), indicating kidney injury. We further revealed via histological observation that Cd damaged structural integrity of kidneys, as evidenced by renal glomerulus and renal tubular injury, hallmark phenotypes of apoptosis, and mitochondrial damage, suggesting that mitochondria damage and apoptosis were involved in Cd-induced kidney injury. Moreover, Cd exposure decreased ATPase (Na⁺/K⁺-ATPase, Ca²⁺-ATPase, Mg²⁺-ATPase, and Ca²⁺Mg²⁺-ATPase) activities as well as PGC-1a and Mfn2 levels, while increased Drp1 and PINK1 levels as well as LC3-II/LC3-I ratio, which indicated that Cd-impaired renal energy metabolism was related to mitochondrial dysfunction. Additionally, we found that Cd induced oxidative stress (abnormal levels of SOD, CAT, GPX, MDA, and H₂O₂) in kidneys, which was involved in triggering mitochondrial dysfunction and further impairing mitochondrial energy metabolism. Moreover, the occurrence of mitochondria-dependent apoptosis was found after Cd-exposure in common carp kidneys, as indicated by enhanced levels of Bax, CytC, APAF1, Caspase-9, and Caspase-3, while declined level of Bcl-2. Subsequently, we confirmed a time-dependent nephrotoxicity of Cd to common carp via IBR assessment. In conclusion, Cd induced time-dependent nephrotoxicity in common carp via mitochondrial pathway. This mitochondria-oriented study shed light on underlying mechanisms of Cd-induced renal pathologies and provided a theoretical basis for evaluating Cd toxicity to aquatic organisms.

The STAT1/HMGB1/NF-κB pathway in chronic inflammation and kidney injury after cisplatin exposure

Rationale: Cisplatin, a potent chemotherapeutic drug, induces side effects in normal tissues including the kidney. To reduce the side effects, repeated low-dose cisplatin (RLDC) is commonly used in clinical setting. While RLDC reduces acute nephrotoxicity to certain extents, a significant portion of patients later develop chronic kidney problems, underscoring the need for novel therapeutics to alleviate the long-term sequelae of RLDC therapy. Methods: In vivo, the role of HMGB1 was examined by testing HMGB1 neutralizing antibodies in RLDC mice. In vitro, the effects of HMGB1 knockdown on RLDC-induced nuclear factor-κB (NF-κB) activation and fibrotic phenotype changes were tested in proximal tubular cells. To study signal transducer and activator of transcription 1 (STAT1), siRNA knockdown and its pharmacological inhibitor Fludarabine were used. We also searched the Gene Expression Omnibus (GEO) database for transcriptional expression profiles and evaluated kidney biopsy samples from CKD patients to verify the STAT1/HMGB1/NF-κB signaling axis. Results: We found that RLDC induced kidney tubule damage, interstitial inflammation, and fibrosis in mice, accompanied by up-regulation of HMGB1. Blockage of HMGB1with neutralizing antibodies and Glycyrrhizin suppressed NF-κB activation and associated production of pro-inflammatory cytokines, reduced tubular injury and renal fibrosis, and improved renal function after RLDC treatment. Consistently, knockdown of HMGB1 decreased NF-κB activation and prevented the fibrotic phenotype in RLDC-treated renal tubular cells. At the upstream, knockdown of STAT1 suppressed HMGB1 transcription and cytoplasmic accumulation in renal tubular cells, suggesting a critical role of STAT1 in HMGB1 activation. Upregulation of STAT1/HMGB1/NF-κB along with inflammatory cytokines was also verified in kidney tissues of CKD patients. Conclusion: These results unravel the STAT1/HMGB1/NF-κB pathway that contributes to persistent inflammation and chronic kidney problems after cisplatin nephrotoxicity, suggesting new therapeutic targets for kidney protection in cancer patients receiving cisplatin chemotherapy.

Omega-3 polyunsaturated fatty acids inhibit cardiomyocyte apoptosis and attenuate sepsis-induced cardiomyopathy

OBJECTIVES

Sepsis can cause myocardial injury, which is one of the leading causes of death in critically ill patients. Fish oil rich in omega-3 polyunsaturated fatty acids (PUFAs) in ultralong chains has immunomodulatory effects and can inhibit the production of various critically ill proinflammatory cytokines. Therefore, this study focused on whether ω-3 PUFAs have a protective effect on sepsis-induced cardiomyopathy (SIC).

METHODS

Male 6-8 weeks old C57BL/6 mice were pretreated with 3% special fish oil supplement rat food for seven consecutive days prior to surgery. Cecal ligation and puncture (CLP) was perfromed to induce polymicrobial sepsis.The cardiac function was assessed by echocardiography, apoptosis of cardiomyocyte were detected by TUNEL assay and Western blotting, and the level of TNF-α, IL-6, and IL-1β in plasma was determined 24h after CLP.

RESULTS

Pretreatment with omega-3 PUFAs attenuated cardiomyocyte apoptosis, decreased the production of proinflammatory cytokines, attenuated the SIC, and improved the survival rate of septic mice induced by CLP.

CONCLUSIONS

ω-3 PUFAs alleviate SIC through attenuating cardiomyocyte apoptosis, which provides a new direction for the prevention and treatment of SIC.

Glycyrrhizin prevents 3-nitropropionic acid-induced neurotoxicity by downregulating HMGB1/TLR4/NF-κB p65 signaling, and attenuating oxidative stress, inflammation, and apoptosis in rats

AIMS

Glycyrrhizin (Glyc) is a saponin triterpenoid that has signified its efficacy against Huntington's disease (HD). Nonetheless, its mechanism has not been fully clarified. Accordingly, this study was designed to evaluate the plausible mechanism of action of Glyc against 3-nitropropionic acid (3-NP)-induced HD.

MAIN METHODS

Rats were treated with Glyc (50 mg/kg, i.p.) for 3 weeks and 3-NP (10 mg/kg, i.p.) was administered at the latter 2 weeks alongside to induce HD.

KEY FINDINGS

Animals exposed to 3-NP revealed a reduction in body weight, neurobehavioral abnormalities, and various deleterious effects related to overexpression of HMGB1 such as oxidative stress, apoptosis, and inflammation. Promisingly, Glyc administration provided valuable effects by reversing the decline in body weight with improved neurobehavioral deficits. Ameliorating oxidative stress via restoring GSH, SOD, and Nrf2 alongside with MDA suppression was evident. Furthermore, Glyc switched the HMGB1/TLR4/NF-κB p65 signaling off, reduced IL-6, IL-β, TNF-α, caspase-3, and increased Bcl-2 as well as BDNF. All these beneficial effects were mirrored by a better histopathological picture upon using Glyc that suppressed gliosis by reducing GFAP expression as observed in the immunohistochemistry results.

SIGNIFICANCE

Accordingly, the current study demonstrated a promising neuroprotective effect of Glyc against experimentally induced HD through alleviating deleterious events by diverse mechanisms.

Toll-like receptors 2 and 4 stress signaling and sodium-glucose cotransporter-2 in kidney disease

Kidney disease is the 6th fastest-growing cause of death and a serious global health concern that urges effective therapeutic options. The inflammatory response is an initial reaction from immune and parenchymal cells in kidney diseases. Toll-like receptors (TLR) 2 and 4 are highly expressed by various kidney cells and respond to 'signaling danger' proteins, such as high mobility group box binding protein 1 (HMGB1) and prompt the progression of kidney disease by releasing inflammatory mediators. Burgeoning reports suggest that both SGLT2 and ER stress elevates TLR2/4 signaling via different axis. Moreover, SGLT2 signaling aggravates inflammation under the disease condition by promoting the NLR family pyrin domain-containing three inflammasomes and ER stress. Intriguingly, TLR2/4 downstream adaptors activate ER stress regulators. The above-discussed interactions imply that TLR2/4 does more than immune response during kidney disease. Here, we discuss in detail evidence of the roles and regulation of TLR2/4 in the context of a relationship between ER stress and SGLT2. Also, we highlighted different preclinical studies of SGLT2 inhibitors against TLR2/4 signaling in various kidney diseases. Moreover, we discuss the observational and interventional evidence about the relation between TLR2/4, ER stress, and SGLT2, which may represent the TLR2/4 as a potential therapeutic target for kidney disease.

Analysis of the network pharmacology and the structure-activity relationship of glycyrrhizic acid and glycyrrhetinic acid

Licorice, a herbal product derived from the root of Glycyrrhiza species, has been used as a sweetening agent and traditional herbal medicine for hundreds of years. Glycyrrhizic acid (GL) and glycyrrhetinic acid (GA) are the most important active ingredients in licorice. Both GL and GA have pharmacological effects against tumors, inflammation, viral infection, liver diseases, neurological diseases, and metabolic diseases. However, they also exhibit differences. KEGG analysis indicated that licorice is involved in neuroactive ligand‒receptor interactions, while 18β-GA is mostly involved in arrhythmogenic right ventricular cardiomyopathy. In this article, we comprehensively review the therapeutic potential of GL and GA by focusing on their pharmacological effects and working mechanisms. We systemically examine the structure-activity relationship of GL, GA and their isomers. Based on the various pharmacological activities of GL, GA and their isomers, we propose further development of structural derivatives of GA after chemical structure modification, with less cytotoxicity but higher targeting specificity. More research is needed on the clinical applications of licorice and its active ingredients.

Tanshinone IIA reduces AQP4 expression and astrocyte swelling after OGD/R by inhibiting the HMGB1/RAGE/NF-κB/IL-6 pro-inflammatory axis

This study aimed to investigate the role of tanshinone IIA (TSO IIA) in astrocytic swelling caused by ischemia–reperfusion-like injury in an in vitro model and the molecular mechanisms underlying this effect. Primary brain astrocytes were cultured under conditions of glucose and oxygen deprivation and reoxygenation (OGD/R). The study explored the effects of TSO IIA treatment on cell swelling and injury and the protein levels of aquaporin 4 (AQP4) in the plasma membrane. It then examined the involvement of the high-mobility group box protein 1 (HMGB1)/receptors for advanced-glycation end products (RAGE)/nuclear factor-kappa B (NF-κB)/interleukin-6 (IL-6) pro-inflammatory axis in TSO IIA-mediated protection. The treatment with TSO IIA alleviated OGD/R-induced astrocytic swelling and the overclustering of AQP4 protein in the plasma membrane. In addition, TSO IIA significantly reduced the overexpression of HMGB1 and the high levels of the NF-κB protein in the nucleus and of the IL-6 protein in the cytoplasm and extracellular media induced by OGD/R. The combination of TSO IIA and recombinant HMGB1 reversed these effects. The inhibition of the RAGE, the receptor of HMGB1, induced results similar to those of TSO IIA. In addition, exogenous IL-6 reversed TSO IIA-mediated effect on AQP4 overclustering and cell swelling. TSO IIA significantly reduced astrocyte swelling after OGD/R injury in vitro, via blocking the activation of the HMGB1/RAGE/NF-κB/IL-6 pro-inflammatory axis and thereby decreasing the expression of AQP4 in the plasma membrane.

Epigenetic regulation of Toll-like receptors 2 and 4 in kidney disease

Kidney disease affects more than 10% of the worldwide population and causes significant morbidity and mortality. Epigenetic mechanisms such as DNA methylation, histone modifications, and non-coding RNAs (ncRNAs) play a pivotal role in the progression of kidney disease. These epigenetic mechanisms are reversible and majorly involved in regulating gene expression of inflammatory, fibrotic, and apoptotic proteins. Emerging data suggest that the Toll-like receptor 2 and Toll-like receptor 4 (TLR2 and TLR4) are expressed by almost all types of kidney cells and known for promoting inflammation by recognizing damage-associated molecular proteins (DAMPs). Epigenetic mechanisms regulate TLR2 and TLR4 signaling in various forms of kidney disease where different histone modifications promote the transcription of the TLR2 and TLR4 gene and its ligand high mobility group box protein 1 (HMGB1). Moreover, numerous long non-coding RNAs (LncRNAs) and microRNAs (miRNAs) modulate TLR2 and TLR4 signaling in kidney disease. However, the precise mechanisms behind this regulation are still enigmatic. Studying the epigenetic mechanisms involved in the regulation of TLR2 and TLR4 signaling in the development of kidney disease may help in understanding and finding novel therapeutic strategies. This review discusses the intricate relationship of epigenetic mechanisms with TLR2 and TLR4 in different forms of kidney diseases. In addition, we discuss the different lncRNAs and miRNAs that regulate TLR2 and TLR4 as potential therapeutic targets in kidney disease.

High mobility group box 1 and homocysteine as preprocedural predictors for contrast-induced acute kidney injury after percutaneous coronary artery intervention

PURPOSE

High mobility group box 1 (HMGB1) and homocysteine (Hcy) play important roles in contrast-induced acute kidney injury (CI-AKI). We compared HMGB1 to Hcy as preprocedural predictors for CI-AKI in coronary artery disease (CAD) patients after percutaneous coronary artery intervention (PCI).

METHODS

We included 257 eligible patients who were categorized into CI-AKI ( +) and CI-AKI ( -) group. The differences in clinical characteristics and biochemical indexes between two groups were analyzed.

RESULTS

We observed that thirty-eight (14.8%) of 257 eligible CAD patients developed CI-AKI. HMGB1 (14.65 [11.13-24.89] vs 10.88 [7.94-13.23], p < 0.001) and Hcy (14.07 [12.07-17.31] vs 12.09 [10.71-13.47], p < 0.001) increased significantly in CI-AKI ( +) group. Both age (r = 0.210, p = 0.001), serum creatinine (r = 0.509, p < 0.001), eGFR (r =  - 0.459, p < 0.001) and Hcy (r = 0.531, p < 0.001) were significantly correlated with HMGB1. Among all patients, HMGB1 (OR 1.181, 95% CI 1.081-1.290, p < 0.001) and Hcy (OR 1.260, 95% CI 1.066-1.489, p = 0.007) were independent predictors for the development of CI-AKI. We built the propensity score matching (PSM) using 38 pairs of patients. After adjustment, HMGB1 (OR 1.169, 95% CI 1.035-1.322, p = 0.012) and Hcy (OR 1.457, 95% CI 1.064-1.997, p = 0.019) were also independent predictors for the development of CI-AKI. Both HMGB1 (AUC: 0.704, 95% CI: 0.588-0.819, p = 0.002) and Hcy (AUC: 0.708, 95% CI: 0.593-0.823, p = 0.002) had predictive values for CI-AKI.

CONCLUSION

There is a significant positive association between HMGB1 and Hcy in CAD patients. Both HMGB1 and Hcy are potential preprocedural predictors of CI-AKI after PCI.