Lithium exacerbates hepatic ischemia/reperfusion injury by inhibiting GSK-3β/NF-κB-mediated protective signaling in mice

Physiological and cellular mechanisms of ischemic preconditioning microRNAs-mediated in underlying of ischemia/reperfusion injury in different organs

Ischemia-reperfusion (I/R) injury, as a pathological phenomenon, takes place when blood supply to an organ is disrupted and then aggravated during restoration of blood flow. Ischemic preconditioning (IPC) is a potent method for attenuating subsequent events of IR damage in numerous organs. IPC protocol is determined by a brief and sequential time periods of I/R before the main ischemia. MicroRNAs are endogenous non-coding RNAs that regulate post-transcriptionally target mRNA translation via degrading it and/or suppressing protein synthesis. This review introduces the physiological and cellular mechanisms of ischemic preconditioning microRNAs-mediated after I/R insult in different organs such as the liver, kidney, heart, brain, and intestine. Data of this review have been collected from the scientific articles published in databases such as Science Direct, Scopus, PubMed, Web of Science, and Scientific Information Database from 2000 to 2023. Based on these literature studies, IPC/IR intervention can affect cellular mechanisms including oxidative stress, apoptosis, angiogenesis, and inflammation through up-regulation or down-regulation of multiple microRNAs and their target genes.

Mechanistic Implications of GSK and CREB Crosstalk in Ischemia Injury

Ischemia-reperfusion (IR) injury is a damage to an organ when the blood supply is less than the demand required for normal functioning, leading to exacerbation of cellular dysfunction and death. IR injury occurs in different organs like the kidney, liver, heart, brain, etc., and may not only involve the ischemic organ but also cause systemic damage to distant organs. Oxygen-glucose deprivation in cells causes oxidative stress, calcium overloading, inflammation, and apoptosis. CREB is an essential integrator of the body's various physiological systems, and it is widely accepted that dysfunction of CREB signaling is involved in many diseases, including ischemia-reperfusion injury. The activation of CREB can provide life to a cell and increase the cell's survival after ischemia. Hence, GSK/CREB signaling pathway can provide significant protection to cells of different organs after ischemia and emerges as a futuristic strategy for managing ischemia-reperfusion injury. Different signaling pathways such as MAPK/ERK, TLR4/MyD88, RISK, Nrf2, and NF-κB, get altered during IR injury by the modulation of GSK-3 and CREB (cyclic AMP response element (CRE)-binding protein). GSK-3 (protein kinase B) and CREB are the downstream targets for fulfilling the roles of various signaling pathways. Calcium overloading during ischemia increases the expression of calcium-calmodulin-dependent protein kinase (CaMK), which subsequently activates CREB-mediated transcription, thus promoting the survival of cells. Furthermore, this review highlights the crosstalk between GSK-3 and CREB, promoting survival and rendering the cells resistant to subsequent severe ischemia.

Divergent Directionality of Immune Cell-Specific Protein Expression between Bipolar Lithium Responders and Non-Responders Revealed by Enhanced Flow Cytometry

Background and Objectives: There is no biomarker to predict lithium response. This study used CellPrint™ enhanced flow cytometry to study 28 proteins representing a spectrum of cellular pathways in monocytes and CD4⁺ lymphocytes before and after lithium treatment in patients with bipolar disorder (BD). Materials and Methods: Symptomatic patients with BD type I or II received lithium (serum level ≥ 0.6 mEq/L) for 16 weeks. Patients were assessed with standard rating scales and divided into two groups, responders (≥50% improvement from baseline) and non-responders. Twenty-eight intracellular proteins in CD4⁺ lymphocytes and monocytes were analyzed with CellPrint™, an enhanced flow cytometry procedure. Data were analyzed for differences in protein expression levels. Results: The intent-to-treat sample included 13 lithium-responders (12 blood samples before treatment and 9 after treatment) and 11 lithium-non-responders (11 blood samples before treatment and 4 after treatment). No significant differences in expression between the groups was observed prior to lithium treatment. After treatment, the majority of analytes increased expression in responders and decreased expression in non-responders. Significant increases were seen for PDEB4 and NR3C1 in responders. A significant decrease was seen for NR3C1 in non-responders. Conclusions: Lithium induced divergent directionality of protein expression depending on the whether the patient was a responder or non-responder, elucidating molecular characteristics of lithium responsiveness. A subsequent study with a larger sample size is warranted.

Macrophage GSK3β-deficiency inhibits the progression of hepatocellular carcinoma and enhances the sensitivity of anti-PD1 immunotherapy

BACKGROUND

Glycogen synthase kinase 3β (GSK3β) was originally discovered to regulate glycogen synthesis and show a relationship to tumors. However, the biological functions of GSK3β in tumor-associated macrophages (TAMs) in cancers including hepatocellular carcinoma (HCC) remain unclear.

METHODS

The enrichment of GSK3β in tumor tissues was assessed by Gene Expression Omnibus (GEO) database. The in vitro and in vivo assays assisted in evaluating how GSK3β in TAMs affected HCC in terms of proliferation, invasion and migration. Immunofluorescence was used to assess GSK3β expression in TAMs in the anti-PD1 therapy non-responsive HCC group and the responsive group. Western blot and coimmunoprecipitation were performed to demonstrate the interaction between GSK3β and PD-L1. We carried out in vivo experiments in a C57BL/6 mouse model of HCC established through subcutaneous injection.

RESULTS

GEO single-cell RNA sequencing data suggested that GSK3β was highly enriched in TAMs of HCC. According to in vitro and in vivo experiments, reducing GSK3β in TAMs inhibits the cancer cell proliferation, invasion, and migration. The immunofluorescence and immunohistochemistry results confirmed that the GSK3β is significantly upregulated in TAMs of the anti-PD1 therapy non-responsive group in comparison with the responsive group. In vitro and in vivo experiments confirmed that reduced GSK3β in TAMs are capable of enhancing the sensitivity of anti-PD1 immunotherapy for HCC by decreasing PD-L1 ubiquitination. Mass spectrometry results suggested that high expression of CD14⁺GSK3β⁺ in the peripheral blood mononuclear cell (PBMC) can predict non-responsive to anti-PD1 treatment. Moreover, escitalopram is confirmed to act as GSK3β inhibitor that can increase the sensitivity of anti-PD1 immunotherapy for HCC.

CONCLUSIONS

This study revealed that macrophage GSK3β deficiency can inhibit the development of HCC by inhibiting the M2 phenotype and enhance the sensitivity of anti-PD1 immunotherapy for HCC by decreasing PD-L1 ubiquitination. The expression of CD14⁺GSK3β⁺ in PBMC can noninvasively predict anti-PD1 sensitivity in HCC patients, which provides novel strategies to predict anti-PD1 sensitivity, increase anti-PD1 therapeutic effect, and bring new hope for HCC patients.

Progress and Prospects of Non-Canonical NF-κB Signaling Pathway in the Regulation of Liver Diseases

Non-canonical nuclear factor kappa B (NF-κB) signaling pathway regulates many physiological and pathological processes, including liver homeostasis and diseases. Recent studies demonstrate that non-canonical NF-κB signaling pathway plays an essential role in hyperglycemia, non-alcoholic fatty liver disease, alcoholic liver disease, liver regeneration, liver injury, autoimmune liver disease, viral hepatitis, and hepatocellular carcinoma. Small-molecule inhibitors targeting to non-canonical NF-κB signaling pathway have been developed and shown promising results in the treatment of liver injuries. Here, the recent advances and future prospects in understanding the roles of the non-canonical NF-κB signaling pathways in the regulation of liver diseases are discussed.

Attenuation of hepatic ischemia‑reperfusion injury by adipose stem cell‑derived exosome treatment via ERK1/2 and GSK‑3β signaling pathways

Exosomes are an emerging therapeutic tool for the treatment of tissue injuries. In the present study, the protective effect of isolated exosomes from adipose‑derived stem cells (ADSCs‑exo) against hepatic ischemia‑reperfusion (I/R) injury was explored. Hepatic I/R injury was achieved by inducing ischemia for 60 min followed by reperfusion for 2 and 6 h. Pre‑treatment with ADSCs‑exo revealed a significant reduction in necrosis and apoptosis in liver tissue induced by I/R injury. Hypoxic oxidative stress was managed by exosome‑mediated reduced reactive oxygen species and increased superoxide dismutase that in turn protected mitochondrial damage and apoptosis. Reduction in inflammatory mediators such as IL‑1β and TNF‑α was also observed and protection of hepatocytes from I/R injury was evidenced by a significant decrease in biochemical markers of liver damage (alanine transaminase, aspartate transaminase and lactate dehydrogenase). Exosomal prostaglandin E2 (PGE2)‑mediated ERK1/2 and GSK‑3β phosphorylation were revealed to increase Bcl‑2 and decrease Bax expression with mitochondrial permeability transition pore‑inhibition which may be considered a prime mechanism of exosome‑mediated hepatoprotection. In conclusion, our results indicated that ADSCs‑exo pre‑treatment is effective in protecting liver I/R injury.

Sevoflurane preconditioning protects experimental ischemic stroke by enhancing anti-inflammatory microglia/macrophages phenotype polarization through GSK-3β/Nrf2 pathway

Aims

Sevoflurane preconditioning (SPC) results in cerebral ischemic tolerance; however, the mechanism remains unclear. Promoting microglia/macrophages polarization from pro‐inflammatory state to anti‐inflammatory phenotype has been indicated as a potential treatment target against ischemic stroke. In this study, we aimed to assess the effect of SPC on microglia polarization after stroke and which signaling pathway was involved in this transition.

Methods

Mouse primary microglia with SPC were challenged by oxygen‐glucose deprivation (OGD) or lipopolysaccharide (LPS), and mice with SPC were subjected to middle cerebral artery occlusion (MCAO). Then, the mRNA and protein levels of pro‐inflammatory/anti‐inflammatory factors were analyzed. GSK‐3β phosphorylation and Nrf2 nuclear translocation were measured. The mRNA and protein expression of pro‐inflammatory/anti‐inflammatory factors, neurological scores, infarct volume, cellular apoptosis, the proportion of pro‐inflammatory/anti‐inflammatory microglia/macrophages, and the generation of super‐oxidants were examined after SPC or GSK‐3β inhibitor TDZD treatment with or without Nrf2 deficiency.

Results

Sevoflurane preconditioning promoted anti‐inflammatory and inhibited pro‐inflammatory microglia/macrophages phenotype both in vitro and in vivo. GSK‐3β phosphorylation at Ser9 was increased after SPC. Both SPC and TDZD administration enhanced Nrf2 nuclear translocation, reduced pro‐inflammatory microglia/macrophages markers expression, promoted anti‐inflammatory markers level, and elicited a neuroprotective effect. Nrf2 deficiency abolished the promoted anti‐inflammatory microglia/macrophages polarization and ischemic tolerance induced by TDZD treatment. The reduced percentage of pro‐inflammatory positive cells and super‐oxidants generation induced by SFC or TDZD was also reversed by Nrf2 knockdown.

Conclusions

Our results indicated that SPC exerts brain ischemic tolerance and promotes anti‐inflammatory microglia/macrophages polarization by GSK‐3β‐dependent Nrf2 activation, which provides a novel mechanism for SPC‐induced neuroprotection.

Targeting Glycogen Synthase Kinase 3 Beta Regulates CD47 Expression After Myocardial Infarction in Rats via the NF-κB Signaling Pathway

The aim of this study was to investigate the effects of the GSK-3β/NF-κB pathway on integrin-associated protein (CD47) expression after myocardial infarction (MI) in rats. An MI Sprague Dawley rat model was established by ligating the left anterior descending coronary artery. The rats were divided into three groups: Sham, MI, and SB + MI (SB216763) groups. Immunohistochemistry was used to observe the changes in cardiac morphology. A significant reduction in the sizes of fibrotic scars was observed in the SB + MI group compared to that in the MI group. SB216763 decreased the mRNA and protein expression of CD47 and NF-κB during MI. Primary rat cardiomyocytes (RCMs) and the H9c2 cell line were used to establish in vitro hypoxia models. Quantitative real-time PCR and western blotting analyses were conducted to detect mRNA and protein expression levels of CD47 and NF-κB and apoptosis-related proteins, respectively. Apoptosis of hypoxic cells was assessed using flow cytometry. SB216763 reduced the protein expression of CD47 and NF-κB in RCMs and H9c2 cells under hypoxic conditions for 12 h, and alleviated hypoxia-induced apoptosis. SN50 (an NF-κB inhibitor) also decreased CD47 protein expression in RCMs and H9c2 cells under hypoxic conditions for 12 h and protected cells from apoptosis. GSK-3β upregulates CD47 expression in cardiac tissues after MI by activating NF-κB, which in turn leads to myocardial cell damage and apoptosis.

Discovery of Novel Benzothiazepinones as Irreversible Covalent Glycogen Synthase Kinase 3β Inhibitors for the Treatment of Acute Promyelocytic Leukemia

Recently, irreversible inhibitors have attracted great interest in antitumors due to their advantages of forming covalent bonds to target proteins. Herein, some benzothiazepinone compounds (BTZs) have been designed and synthesized as novel covalent GSK-3β inhibitors with high selectivity for the kinase panel. The irreversible covalent binding mode was identified by kinetics and mass spectrometry, and the main labeled residue was confirmed to be the unique Cys14 that exists only in GSK-3β. The candidate 4-3 (IC₅₀ = 6.6 μM) showed good proliferation inhibition and apoptosis-inducing ability to leukemia cell lines, low cytotoxicity on normal cell lines, and no hERG inhibition, which hinted the potential efficacy and safety. Furthermore, 4-3 exhibited decent pharmacokinetic properties in vivo and remarkably inhibited tumor growth in the acute promyelocytic leukemia (APL) mouse model. All the results suggest that these newly irreversible BTZ compounds might be useful in the treatment of cancer such as APL.

Roles of TRAFs in Ischemia-Reperfusion Injury

Tumor necrosis factor receptor-associated factor (TRAF) proteins are a family of signaling molecules that function downstream of multiple receptor signaling pathways, and they play a pivotal role in the regulation of intracellular biological progresses. These TRAF-dependent signaling pathways and physiological functions have been involved in the occurrence and progression of ischemia-reperfusion injury (IRI), which is a common pathophysiological process that occurs in a wide variety of clinical events, including ischemic shock, organ transplantation, and thrombolytic therapy, resulting in a poor prognosis and high mortality. IRI occurs in multiple organs, including liver, kidney, heart, lung, brain, intestine, and retina. In recent years, mounting compelling evidence has confirmed that the genetic alterations of TRAFs can cause subversive phenotype changes during IRI of those organs. In this review, based on current knowledge, we summarized and analyzed the regulatory effect of TRAFs on the IRI of various organs, providing clear direction and a firm theoretical basis for the development of treatment strategies to manipulate TRAF proteins or TRAF-dependent signaling pathways in IRI-related diseases.

Administration of Momordica charantia Enhances the Neuroprotection and Reduces the Side Effects of LiCl in the Treatment of Alzheimer's Disease

Recently, the use of natural food supplements to reduce the side effects of chemical compounds used for the treatment of various diseases has become popular. Lithium chloride (LiCl) has some protective effects in neurological diseases, including Alzheimer’s disease (AD). However, its toxic effects on various systems and some relevant interactions with other drugs limit its broader use in clinical practice. In this study, we investigated the in vitro and in vivo pharmacological functions of LiCl combined with Momordica charantia (MC) in the treatment of AD. The in vitro results show that the order of the neuroprotective effect is MC5, MC3, MC2, and MC5523 under hyperglycemia or tau hyperphosphorylation. Therefore, MC5523 (80 mg/kg; oral gavage) and/or LiCl (141.3 mg/kg; intraperitoneal injection) were applied to ovariectomized (OVX) 3×Tg-AD female and C57BL/6J (B6) male mice that received intracerebroventricular injections of streptozotocin (icv-STZ, 3 mg/kg) for 28 days. We found that the combined treatment not only increased the survival rate by reducing hepatotoxicity but also increased neuroprotection associated with anti-gliosis in the icv-STZ OVX 3×Tg-AD mice. Furthermore, the cotreatment with MC5523 and LiCl prevented memory deficits associated with reduced neuronal loss, gliosis, oligomeric Aβ level, and tau hyperphosphorylation and increased the expression levels of synaptic-related protein and pS9-GSK3β (inactive form) in the icv-STZ B6 mice. Therefore, MC5523 combined with LiCl could be a potential strategy for the treatment of AD.

Enhanced hepatic glycogen synthesis and suppressed adenosine deaminase activity by lithium attenuates hepatic triglyceride accumulation in nicotine-exposed rats

Reduced liver glycogen synthesis might signify increased glucose flux towards fat synthesis and triggers hepatic triglyceride accumulation and dysmetabolism. Adenosine deaminase (ADA) reduces adenosine content which increases glycogenolysis. In the present study, we evaluate the effect of modulating glycogen synthesis and ADA by lithium chloride (LiCl) on nicotine-induced dysmetabolism. Twenty four male Wistar rats (n = 6/group) were allotted into four groups namely; vehicle-treated (po), nicotine-treated (1.0 mg/kg; po), LiCl-treated (5.0 mg/kg; po) and nicotine + LiCl-treated groups. The treatments lasted for 8 weeks. Nicotine exposure resulted in reduced body weight gain, liver weight, visceral adiposity, glycogen content and synthase. Along with increased insulin resistance (IR), fasting plasma glucose, lactate, plasma and hepatic ADA, XO, UA, and triglyceride (TG), total cholesterol (TC), free fatty acid, lipid peroxidation and liver injury markers. However, plasma and hepatic glucose-6-phosphate dehydrogenase-dependent antioxidant defenses were not affected by nicotine exposure. Concurrent treatment with LiCl normalizes all alterations with exception of hepatic TC. This result shows that enhancement of hepatic glycogen synthesis and suppression of ADA/XO/uric acid pathway by lithium can salvage the liver from nicotine-induced TG accumulation.

Glycogen synthase kinase 3β promotes liver innate immune activation by restraining AMP-activated protein kinase activation

BACKGROUND & AIMS

Glycogen synthase kinase 3β (Gsk3β [Gsk3b]) is a ubiquitously expressed kinase with distinctive functions in different types of cells. Although its roles in regulating innate immune activation and ischaemia and reperfusion injuries (IRIs) have been well documented, the underlying mechanisms remain ambiguous, in part because of the lack of cell-specific tools in vivo.

METHODS

We created a myeloid-specific Gsk3b knockout (KO) strain to study the function of Gsk3β in macrophages in a murine liver partial warm ischaemia model.

RESULTS

Compared with controls, myeloid Gsk3b KO mice were protected from IRI, with diminished proinflammatory but enhanced anti-inflammatory immune responses in livers. In bone marrow-derived macrophages, Gsk3β deficiency resulted in an early reduction of Tnf gene transcription but sustained increase of Il10 gene transcription on Toll-like receptor 4 stimulation in vitro. These effects were associated with enhanced AMP-activated protein kinase (AMPK) activation, which led to an accelerated and higher level of induction of the novel innate immune negative regulator small heterodimer partner (SHP [Nr0b2]). The regulatory function of Gsk3β on AMPK activation and SHP induction was confirmed in wild-type bone marrow-derived macrophages with a Gsk3 inhibitor. Furthermore, we found that this immune regulatory mechanism was independent of Gsk3β Ser9 phosphorylation and the phosphoinositide 3-kinase-Akt signalling pathway. In vivo, myeloid Gsk3β deficiency facilitated SHP upregulation by ischaemia-reperfusion in liver macrophages. Treatment of Gsk3b KO mice with either AMPK inhibitor or SHP small interfering RNA before the onset of liver ischaemia restored liver proinflammatory immune activation and IRI in these otherwise protected hosts. Additionally, pharmacological activation of AMPK protected wild-type mice from liver IRI, with reduced proinflammatory immune activation. Inhibition of the AMPK-SHP pathway by liver ischaemia was demonstrated in tumour resection patients.

CONCLUSIONS

Gsk3β promotes innate proinflammatory immune activation by restraining AMPK activation.

LAY SUMMARY

Glycogen synthase kinase 3β promotes macrophage inflammatory activation by inhibiting the immune regulatory signalling of AMP-activated protein kinase and the induction of small heterodimer partner. Therefore, therapeutic targeting of glycogen synthase kinase 3β enhances innate immune regulation and protects liver from ischaemia and reperfusion injury.

The Impact of Chronic Glycogen Synthase Kinase-3 Inhibition on Remodeling of Normal and Pre-Diabetic Rat Hearts

PURPOSE

There is an ongoing search for new drugs and drug targets to treat diseases like Alzheimer's disease, cancer and type 2 diabetes (T2D). Both obesity and T2D are characterized by the development of a cardiomyopathy associated with increased hypertension and compensatory left ventricular hypertrophy. Small, specific glycogen synthase kinase-3 (GSK-3) inhibitors were developed to replace lithium chloride for use in psychiatric disorders. In addition, they were advocated as treatment for T2D since GSK-3 inhibition improves blood glucose handling. However, GSK-3 is a regulator of hypertrophic signalling in the heart via phosphorylation of NFATc3 and β-catenin respectively. In view of this, we hypothesized that chronic inhibition of GSK-3 will induce myocardial hypertrophy or exacerbate existing hypertrophy.

METHODS

Rats with obesity-induced prediabetes were treated orally with GSK-3 inhibitor (CHIR118637 (CT20026)), 30 mg/kg/day for the last 8 weeks of a 20-week diet high in sugar content vs a control diet. Biometric and biochemical parameters were measured, echocardiography performed and localization and co-localization of NFATc3 and GATA4 determined in cardiomyocytes.

RESULTS

Obesity initiated myocardial hypertrophy, evidenced by increased ventricular mass (1.158 ± 0.029 vs 0.983 ± 0.03 g) and enlarged cardiomyocytes (18.86 ± 2.25 vs 14.92 ± 0.50um(2)) in association with increased end-diastolic diameter (EDD = 8.48 ± 0.11 vs 8.15 ± 0.10 mm). GSK-3 inhibition (i) increased ventricular mass only in controls (1.075 ± 0.022 g) and (ii) EDD in both groups (controls: 8.63 ± 0.07; obese: 8.72 ± 0.15 mm) (iii) localized NFATc3 and GATA4 peri-nuclearly.

CONCLUSION

Indications of onset of myocardial hypertrophy in both control and obese rats treated with a GSK-3 inhibitor were found. It remains speculation whether these changes were adaptive or maladaptive.

Altered miR-370 expression in hepatic ischemia-reperfusion injury correlates with the level of nuclear kappa B (NF-κB) related factors

BACKGROUND & AIMS

MicroRNAs (miRNAs) are a class of small endogenous, non-coding RNAs that regulate gene expression at both the transcription and translation levels. Whether miRNAs have taken part in liver ischemia-reperfusion (IR) injury was rarely reported. The purpose of this article is to investigate the potential role of miR-370 in hepatic IR injury.

METHODS

Male C57BL/6 mice were divided into 5 groups (sham-operated group, I/R group, IPC group, antagomir-370 group and antagomir-NC), and the expression levels of miR-370 were assessed by quantitative real-time PCR. Serum enzyme analysis and histological examination of liver were used as the index of the effect of miR-370 on hepatic IR injury and following treatment of mice with antagomir-370 or antagomir-NC. The classical pathway factors of NF-κB (TAK₁, TAB₁, TAB₂, IkBα, IKKα, IKKβ, p50, p65) were studied by quantitative real-time PCR and Western blot.

RESULTS

The results showed that the IR group's miR-370 expression level was significantly upregulated as compared with the sham-operated group and IPC group. Also inhibition of miR-370 led to the low expression levels of miR-370 and low levels of serum aminotransferase and hepatic histological damage as compared with the IR group. Quantitative real-time PCR showed the levels of TAK1, TAB₁, TAB2, IkBα, IKKα, p65 was elevated when improving the miR-370 levels, at the same time, Western blot showed the levels of TAK₁, TAB₁, TAB₂, IkBα, IKKα, IKKβ, p50, p65 were all elevated.

CONCLUSION

miR-370 acting via NF-κB might play a crucial role in hepatic IR injury, and inhibition of miR-370 could alleviate the injury to the liver. And miR-370 might positively regulated the NF-κB pathway.

Resveratrol attenuates myocardial ischemia/reperfusion injury through up-regulation of vascular endothelial growth factor B

The objective was to examine the protective effect of resveratrol (RSV) on myocardial ischemia/reperfusion (IR) injury and whether the mechanism was related to vascular endothelial growth factor B (VEGF-B) signaling pathway. Rat hearts were isolated for Langendorff perfusion test and H9c2 cells were used for in vitro assessments. RSV treatment significantly improved left ventricular function, inhibited CK-MB release, and reduced infarct size in comparison with IR group ex vivo. RSV treatment markedly decreased cell death and apoptosis of H9c2 cells during IR. We found that RSV was responsible for the up-regulation of VEGF-B mRNA and protein level, which caused the activation of Akt and the inhibition of GSK3β. Additionally, RSV prevented the generation of reactive oxygen species (ROS) by up-regulating the expression of MnSOD either in vitro or ex vivo. We also found that the inhibition of VEGF-B abolished the cardioprotective effect of RSV, increased apoptosis, and led to the down-regulation of phosphorylated Akt, GSK3β, and MnSOD in H9c2 cells. These results demonstrated that RSV was able to attenuate myocardial IR injury via promotion of VEGF-B/antioxidant signaling pathway. Therefore, the up-regulation of VEGF-B can be a promising modality for clinical myocardial IR injury therapy.

Renoprotective effects of ursolic acid on ischemia/reperfusion‑induced acute kidney injury through oxidative stress, inflammation and the inhibition of STAT3 and NF‑κB activities

Ursolic acid, a pentacyclic triterpene compound with low toxicity and easy availability, has a variety of biological activities, including antitumor, antioxidant, antihepatitis, anti‑inflammatory and antibacterial effects. The present study aimed to investigate the renoprotective effects of ursolic acid on ischemia/reperfusion‑induced acute kidney injury (I/R‑IAKI) in rats associated with its antioxidant and anti‑inflammatory effects, as well as interference with the signal transducer and activator of transcription (STAT)3/nuclear factor (NF)‑κB signaling pathway. The present study demonstrated that pre‑treatment with ursolic acid significantly increased renal functioning and attenuated increases of serum angiotensin II levels in rats subjected to I/R‑IAKI. In addition, I/R‑IAKI‑induced inflammation and oxidative stress were significantly reduced by pre‑treatment with ursolic acid. Furthermore, ursolic acid significantly suppressed the upregulation of STAT3, NF‑κB and caspase‑3 activities in rats following I/R‑IAKI. These results indicated that ursolic acid may be a potential drug for reducing I/R‑IAKI through suppression of inflammation and oxidative stress damage, as well as modulation of STAT3 and NF‑κB activities.

Glycogen synthase kinase 3β inhibition promotes human iTreg differentiation and suppressive function

Induced regulatory T cells (iTregs) are essential to maintain immunological tolerance, immune homeostasis and prevention of autoimmunity. Some studies suggest that glycogen synthase kinase 3β (GSK3β) is involved in the mouse iTreg differentiation; however, whether GSK3β inhibits or enhances iTreg differentiation is still a matter of controversy. To address this issue, we have utilized human naïve CD4(+) T cells and investigated whether GSK3 activity changes during iTreg differentiation and whether altering GSK3 activity influences the development of iTregs and its suppressive function. As a constitutively activated kinase, during iTreg differentiation GSK3β became quickly deactivated (phosphorylated at serine 9), which is dependent on MAPK pathway rather than PI3-kinase/Akt pathway. Our results indicated that inhibition of GSK3β by specific inhibitors, SB216763 or TDZD-8, promoted the differentiation of iTreg and increased their suppressive activity. In contrast, overexpression of GSK3β significantly inhibited iTreg differentiation. Furthermore, GSK3β inhibition enhanced iTreg differentiation through the TGF-β/Smad3 pathway. Taken together, this study demonstrates that inhibition of GSK3β enhances human iTreg differentiation and its suppressive activity, and provides a rationale to target GSK3β as a novel immunotherapeutic strategy.

Investigations on GSK-3β/NF-kB signaling in stress and stress adaptive behavior in electric foot shock subjected mice

The present study was designed to explore the role of GSK-3β and NF-kB signaling in electric foot shock-induced stress and stress adaptation. Mice were subjected to foot shocks of 0.5mA intensity and 1s duration of 1h to produce acute stress. Animals were exposed to the same stressor for 5 days to induce stress adaptation. The behavioral alterations were assessed using the actophotometer, hole board, open field and social interaction tests. The serum corticosterone levels were assessed as a marker of the HPA axis. The levels of total GSK-3β, p-GSK-3β-S9 and p-NF-kB were determined in the hippocampus, frontal cortex and amygdala. Acute electric foot shock stress produced behavioral and biochemical changes; decreased the levels of p-GSK-3β-S9, produced no change in total GSK-3β levels and increased p-NF-kB levels in the brain. However, repeated exposure of foot shock stress restored the behavioral and biochemical changes along with normalization of p-GSK-3β-S9 and p-NF-kB levels. Administration of AR-A01, a selective GSK-3β inhibitor, or diethyldithiocarbamic acid (DDTC), a selective NF-kB inhibitor, diminished acute stress-induced behavioral and biochemical changes. Furthermore, AR-A014418 normalized acute stress-induced alterations in p-GSK-3β-S9 and p-NF-kB levels, however, DDTC selectively restored NF-kB levels without any change in p-GSK-3β-S9 levels. It probably suggests that NF-kB is a downstream mediator of the GSK-3 signaling cascade. It may conclude that acute stress associated decrease in p-GSK-3β-S9 and increase in p-NF-kB levels in the brain contribute in the development of behavioral and biochemical alterations and normalization of GSK-3β/NF-kB signaling may contribute in stress adaptive behavior in response to repeated electric foot shock-subjected mice.

Mitochondrial Dysfunction and Autophagy in Hepatic Ischemia/Reperfusion Injury

Ischemia/reperfusion (I/R) injury remains a major complication of liver resection, transplantation, and hemorrhagic shock. Although the mechanisms that contribute to hepatic I/R are complex and diverse involving the interaction of cell injury in hepatocytes, immune cells, and endothelium, mitochondrial dysfunction is a cardinal event culminating in hepatic reperfusion injury. Mitochondrial autophagy, so-called mitophagy, is a key cellular process that regulates mitochondrial homeostasis and eliminates damaged mitochondria in a timely manner. Growing evidence accumulates that I/R injury is attributed to defective mitophagy. This review aims to summarize the current understanding of autophagy and its role in hepatic I/R injury and highlight the various therapeutic approaches that have been studied to ameliorate injury.

ATF3-mediated NRF2/HO-1 signaling regulates TLR4 innate immune responses in mouse liver ischemia/reperfusion injury

Activating transcription factor 3 (ATF3) is a stress-induced transcription factor that has been shown to repress inflammatory gene expression in multiple cell types and diseases. However, little is known about the roles and mechanisms of ATF3 in liver ischemia/reperfusion injury (IRI). In warm and cold liver IRI models, we showed that ATF3 deficiency significantly increased ischemia/reperfusion (IR)-stressed liver injury, as evidenced by increased serum alanine aminotransferase levels, histological liver damage, and hepatocellular apoptosis. These may correlate with inhibition of the intrahepatic nuclear factor erythroid-derived 2-related factor 2/heme oxygenase-1 (NRF2/HO-1) signaling pathway leading to enhancing Toll-like receptor 4/nuclear factor kappa beta (TLR4/NF-κB) activation, pro-inflammatory programs and macrophage/neutrophil trafficking, while simultaneously repressing anti-apoptotic molecules in ischemic liver. Interestingly, activation of NRF2/HO-1 signaling using an NRF2 activator, oltipraz (M2), during hepatic IRI-rescued ATF3 anti-inflammatory functions in ATF3-deficient mice. For in vitro studies, ATF3 ablation in lipopolysaccharide (LPS)-stimulated bone marrow-derived macrophages (BMMs) depressed levels of NRF2/HO-1 and PI3K/AKT, resulting in enhanced TLR4/NF-κB activation. Pretreatment of LPS-stimulated BMMs with M2 increased NRF2/HO-1 expression, promoted PI3K/AKT, which in turn suppressed TLR4/NF-κB-mediated proinflammatory mediators. Thus, our results first demonstrate ATF3-mediated NRF2/HO-1 signaling in the regulation of TLR4-driven inflammatory responses in IR-stressed livers. Our findings provide a rationale for a novel therapeutic strategy for managing IR-induced liver injury.

PTPRO plays a dual role in hepatic ischemia reperfusion injury through feedback activation of NF-κB

BACKGROUND & AIMS

Nuclear factor-κB (NF-κB) activation in hepatocytes and macrophages appeared as a double-edged-sword in hepatic ischemia reperfusion (IR) injury. Protein tyrosine phosphatase receptor type O (PTPRO) was recently identified as a potential activator of c-Src, which can in turn activate the NF-κB pathway. In this study, we aimed to determine the change and function of PTPRO in hepatocytes and macrophages during IR.

METHODS

Clinical patients with benign liver condition undergoing liver surgery were recruited in our study. Wild type (WT) and ptpro(-/-) C57BL/6 mice were processed to construct hepatic IR models. Isolated mouse hepatocytes and macrophages were treated with peroxide or TNFα in vitro.

RESULTS

In human and mouse IR models, PTPRO level was decreased in the early phase but reversed in the late phase. In vitro studies demonstrated that NF-κB up-regulated PTPRO transcription. Using ptpro(-/-) mice and primary cells, we found that PTPRO deficiency resulted in reduction of NF-κB activation in both hepatocytes and macrophages and was correlated to c-Src phosphorylation; PTPRO in hepatocytes alleviated, but PTPROt in macrophages exacerbated IR injury.

CONCLUSIONS

PTPRO activates NF-κB in a positive feedback manner, and plays a dual role in hepatic IR injury.

Effect of astilbin on HO-1 expression in hepatic warm ischemia-reperfusion injury

AIM: To study the molecular mechanism behind the effects of astilbin in protecting the liver against warm ischemia-reperfusion injury.

METHODS: C57BL/6 mice were randomly divided into four groups (n = 8 for each): a sham-operated group (Sham), a model control group (I/R), a low dose astilbin treatment group (10 mg/kg) and a high dose astilbin (40 mg/kg) treatment group. At 24 h and 1 h before ischemia, mice in the two treatment groups were intraperitoneally injected with 10 and 40 mg/kg astilbin, respectively. Then 70% hepatic ischemia-reperfusion, including the left and middle hepatic lobes, were induced. The I/R model control group and the sham-operated group were administered with equal volume of normal saline. After 90 min ischemia and 6 h reperfusion of the partial hepatic lobe, blood and liver tissue samples were collected. Serum ALT activity was detected, and the levels of NF-kB and HO-1 in liver tissues were detected by Western blot. The mRNA expression of these molecules was detected by semiquantitative RT-PCR.

RESULTS: Compared with the I/R model control group, serum ALT in both low and high dose treatment groups significantly decreased (sham: 142 U/L ± 25 U/L; I/R: 3521 U/L ± 270 U/L; low dose group: 1766 ± 179U/L; high dose group: 1067 U/L ± 101 U/L, P < 0.01), and the decline was more significant in the high dose group than in the low dose group (P < 0.01). The protein content of NF-kB in liver tissues gradually decreased in both treatment groups compared with the I/R model control group, and was lower in the high dose group than in the low dose group. HO-1 levels gradually increased in treatment groups, and the increase was more significant in the high dose group than in the low dose group. The results of mRNA expression showed a similar trend (sham: 0.53 ± 0.07; I/R: 1.00 ± 0.11; low dose group: 1.17 ± 0.16; high dose group: 1.57 ± 0.07, P < 0.05 or < 0.01).

CONCLUSION: Intervention with astilbin can reduce the high levels of serum ALT caused by ischemia-reperfusion injury, down-regulate the high expression of NF-kB protein and up-regulate the expression of HO-1 protein and mRNA in IRI liver tissues. The protective effect of astilbin against liver IRI is possibly related to the promotion of the expression of HO-1.

Carbon monoxide attenuates dextran sulfate sodium-induced colitis via inhibition of GSK-3β signaling

Endogenous carbon monoxide (CO) is produced by heme oxygenase-1 (HO)-1 which mediates the degradation of heme into CO, iron, and biliverdin. Also, CO ameliorates the human inflammatory bowel diseases and ulcerative colitis. However, the mechanism for the effect of CO on the inflammatory bowel disease has not yet been known. In this study, we showed that CO significantly increases survival percentage, body weight, colon length as well as histologic parameters in DSS-treated mice. In addition, CO inhalation significantly decreased DSS induced pro-inflammatory cytokines by inhibition of GSK-3β in mice model. To support the in vivo observation, TNF-α, iNOS and IL-10 after CO and LiCl treatment were measured in mesenteric lymph node cells (MLNs) and bone marrow-derived macrophages (BMMs) from DSS treated mice. In addition, we determined that CO potentially inhibited GSK-3β activation and decreased TNF-α and iNOS expression by inhibition of NF-κB activation in LPS-stimulated U937 and MLN cells pretreated with CO. Together, our findings indicate that CO attenuates DSS-induced colitis via inhibition of GSK-3β signaling in vitro and in vivo. Importantly, this is the first report that investigated the molecular mechanisms mediated the novel effects of CO via inhibition GSK-3β in DSS-induced colitis model.

Roles for NF-κB and gene targets of NF-κB in synaptic plasticity, memory, and navigation

Although traditionally associated with immune function, the transcription factor nuclear factor kappa B (NF-κB) has garnered much attention in recent years as an important regulator of memory. Specifically, research has found that NF-κB, localized in both neurons and glia, is activated during the induction of long-term potentiation (LTP), a paradigm of synaptic plasticity and correlate of memory. Further, experimental manipulation of NF-κB activation or its blockade results in altered memory and spatial navigation abilities. Genetic knockout of specific NF-κB subunits in mice results in memory alterations. Collectively, such data suggest that NF-κB may be a requirement for memory, although the direction of the response (i.e., memory enhancement or deficit) is inconsistent. A limited number of gene targets of NF-κB have been recently identified in neurons, including neurotrophic factors, calcium-regulating proteins, other transcription factors, and molecules associated with neuronal outgrowth and remodeling. In turn, several key molecules are activators of NF-κB, including protein kinase C and [Ca(++)]i. Thus, NF-κB signaling is complex and under the regulation of numerous proteins involved in activity-dependent synaptic plasticity. The purpose of this review is to highlight the literature detailing a role for NF-κB in synaptic plasticity, memory, and spatial navigation. Secondly, this review will synthesize the research evaluating gene targets of NF-κB in synaptic plasticity and memory. Although there is ample evidence to suggest a critical role for NF-κB in memory, our understanding of its gene targets in neurons is limited and only beginning to be appreciated.

Chronic lithium treatment protects against liver ischemia/reperfusion injury in rats

Lithium has long been widely used in the treatment of bipolar mood disorders. Recent studies have demonstrated that lithium is able to decrease ischemia/reperfusion (I/R) injury in the brain, kidneys, and heart. Because lithium may act on a number of stress and survival pathways, it is of great interest to explore this compound also in the setting of liver I/R injury. In this study, we aimed to evaluate the effects of lithium in a model of liver I/R injury in rats. Chronic treatment with lithium (2 mmol/kg for 3 days before ischemia) decreased I/R injury, whereas acute treatment with a single dose of lithium (2 mmol/kg 1 hour before ischemia) did not confer any protection in a partial hepatic I/R model. Furthermore, rats subjected to chronic lithium treatment had a significantly better survival rate (60%) than saline-treated rats (27%) in a total hepatic I/R survival model. Chronic lithium treatment protected against liver I/R injury, as indicated by lower serum aminotransferase levels, fewer I/R-associated histopathological changes, lower hepatic inflammatory cytokine levels, less neutrophil infiltration, and lower hepatic high-mobility group box expression and serum levels. The mechanism of action of lithium appears to involve its ability to inhibit glycogen synthase kinase 3β activation, modulate mitogen-activated protein kinase activation, inhibit hepatic apoptosis, and induce autophagy. On the basis of these data, we conclude that lithium treatment may be a simple and applicable preconditioning intervention for protecting against liver I/R injury.