Isoliquiritigenin inhibits TNF-α-induced release of high-mobility group box 1 through activation of HDAC in human intestinal epithelial HT-29 cells

The lactate metabolism and protein lactylation in epilepsy

Protein lactylation is a new form of post-translational modification that has recently been proposed. Lactoyl groups, derived mainly from the glycolytic product lactate, have been linked to protein lactylation in brain tissue, which has been shown to correlate with increased neuronal excitability. Ischemic stroke may promote neuronal glycolysis, leading to lactate accumulation in brain tissue. This accumulation of lactate accumulation may heighten neuronal excitability by upregulating protein lactylation levels, potentially triggering post-stroke epilepsy. Although current clinical treatments for seizures have advanced significantly, approximately 30% of patients with epilepsy remain unresponsive to medication, and the prevalence of epilepsy continues to rise. This study explores the mechanisms of epilepsy-associated neuronal death mediated by lactate metabolism and protein lactylation. This study also examines the potential for histone deacetylase inhibitors to alleviate seizures by modifying lactylation levels, thereby offering fresh perspectives for future research into the pathogenesis and clinical treatment of epilepsy.

Epigenetic Effects of Natural Products in Inflammatory Diseases: Recent Findings

Inflammation is an essential step for the etiology of multiple diseases. Clinically, due to the limitations of current drugs for the treatment of inflammatory diseases, such as serious side effects and expensive costs, it is urgent to explore novel mechanisms and medicines. Natural products have received extensive attention recently because of their multi-component and multi-target characteristics. Epigenetic modifications are crucial pathophysiological targets for developing innovative therapies for pharmacological interventions. Investigations examining how natural products improving inflammation through epigenetic modifications are emerging. This review state that natural products relieve inflammation via regulating the gene transcription levels through chromosome structure regulated by histone acetylation levels and the addition or deletion of methyl groups on DNA duplex. They could also exert anti-inflammatory effects by modulating the proteins in typical inflammatory signaling pathways by ubiquitin-related degradation and the effect of glycolysis derived free glycosyls. Studies on epigenetic modifications have the potential to facilitate the development of natural products as therapeutic agents. Future research directed at better understanding of how natural products modulate inflammatory processes through less studied epigenetic modifications including neddylation, SUMOylation, palmitoylation and lactylation, may provide new implications. Meanwhile, higher quality preclinical studies and more powerful clinical evidence are still needed to firmly establish the clinical efficacy of the natural products. Trial Registration: ClinicalTrials.gov Identifier: NCT01764204; ClinicalTrials.gov Identifier: NCT05845931; ClinicalTrials.gov Identifier: NCT04657926; ClinicalTrials.gov Identifier: NCT02330276.

Histone Deacetylases (HDACs) Roles in Inflammation-mediated Diseases; Current Knowledge

The histone acetyl transferases (HATs) and histone deacetylases (HDACs), which are mostly recognized for their involvement in regulating chromatin remodeling via histone acetylation/deacetylation, have been shown to also change several non-histone proteins to regulate other cellular processes. Acetylation affects the activity or function of cytokine receptors, nuclear hormone receptors, intracellular signaling molecules, and transcription factors in connection to inflammation. Some small-molecule HDAC inhibitors are utilized as anticancer medications in clinical settings due to their capability to regulate cellular growth arrest, differentiation, and death. Here, we summarize our present knowledge of the innate and adaptive immunological pathways that classical HDAC enzymes control. The aim is to justify the targeted (or non-targeted) use of inhibitors against certain HDAC enzymes in inflammatory diseases such as arthritis, inflammatory bowel diseases (IBD), airways inflammation and neurological diseases.

Isoliquiritigenin as a modulator of the Nrf2 signaling pathway: potential therapeutic implications

Nuclear factor erythroid-2-related factor 2 (Nrf2), a transcription factor responsible for cytoprotection, plays a crucial role in regulating the expression of numerous antioxidant genes, thereby reducing reactive oxygen species (ROS) levels and safeguarding cells against oxidative stress. Extensive research has demonstrated the involvement of Nrf2 in various diseases, prompting the exploration of Nrf2 activation as a potential therapeutic approach for a variety of diseases. Consequently, there has been a surge of interest in investigating the Nrf2 signaling pathway and developing compounds that can modulate its activity. Isoliquiritigenin (ISL) (PubChem CID:638278) exhibits a diverse range of pharmacological activities, including antioxidant, anticancer, and anti-tumor properties. Notably, its robust antioxidant activity has garnered significant attention. Furthermore, ISL has been found to possess therapeutic effects on various diseases, such as diabetes, cardiovascular diseases, kidney diseases, and cancer, through the activation of the Nrf2 pathway. This review aims to evaluate the potential of ISL in modulating the Nrf2 signaling pathway and summarize the role of ISL in diverse diseases prevention and treatment through modulating the Nrf2 signaling pathway.

Isoliquiritigenin, a potential therapeutic agent for treatment of inflammation-associated diseases

ETHNOPHARMACOLOGICAL RELEVANCE

Licorice is a medicinal herb with a 2000-year history of applications in traditional Chinese medicine. Isoliquiritigenin (ISL) is a bioactive chalcone compound isolated from licorice. It has attracted increasing attention in recent years due to its excellent anti-inflammatory activity.

AIM OF THE STUDY

This study is to provide a comprehensive summary of the anti-inflammatory activity of ISL and the underlying molecular mechanisms, and discuss new insights for its potential clinical applications as an anti-inflammation agent.

MATERIALS AND METHODS

We examined literatures published in the past twenty years from PubMed, Research Gate, Web of Science, Google Scholar, and SciFinder, with single or combined key words of "isoliquiritigenin", "inflammation", and "anti-inflammatory".

RESULTS

ISL elicits its anti-inflammatory activity by mediating various cellular processes. It inhibits the upstream of the nuclear factor kappa B (NF-κB) pathway and activates the nuclear factor erythroid related factor 2 (Nrf2) pathway. In addition, it suppresses the NOD-like receptor protein 3 (NLRP3) pathway and restrains the mitogen-activated protein kinase (MAPK) pathway.

CONCLUSIONS

Current studies indicate a great therapeutical potential of ISL as a drug candidate for treatment of inflammation-associated diseases. However, the pharmacokinetics, biosafety, and bioavailability of ISL remain to be further investigated.

INTERLEUKIN-35 DOWNREGULATES THE IMMUNE RESPONSE OF EFFECTOR CD4 + T CELLS VIA RESTRICTING HIGH MOBILITY GROUP BOX-1 PROTEIN-DEPENDENT AUTOPHAGY IN SEPSIS

ABSTRACT

Background: Immunosuppression is critically involved in the development of sepsis and is closely associated with poor outcomes. The novel role of the anti-inflammatory cytokine IL-35 in sepsis was examined. Methods: Sepsis was induced by in C57BL/6 mice cecal ligation and puncture (CLP). The impacts of IL-35 on effector CD4 + T cells were investigated by examining cell proliferation and the Th1/Th2 ratio in the presence of recombinant IL-35 (rIL-35) or anti-IL-35 (EBI3). The regulatory effect of IL-35 on autophagy was evaluated by measuring autophagy markers and autophagic flux in CLP mice in vivo and in activated effector CD4 + T cells in vitro . Results: IL-35 levels were significantly increased in the serum and spleens of septic mice. rIL-35 administration after CLP further decreased proliferation and the Th1/Th2 ratio in effector CD4 + T cells and significantly shortened the survival time. Sepsis-induced autophagy activation was protective in effector CD4 + T cells and was blocked by rIL-35. The inhibitory effect of IL-35 on autophagy was observed in activated effector CD4 + T cells in vitro , and this effect was mediated by restricting high mobility group box-1 protein (HMGB1) translocation. Conclusion: IL-35 is an immunosuppressive cytokine that impairs CD4 + T-cell proliferation and differentiation in sepsis, and the effect might be mediated by reducing HMGB1-dependent autophagy.

A four-compound remedy AGILe protected H9c2 cardiomyocytes against oxygen glucose deprivation via targeting the TNF-α/NF-κB pathway: Implications for the therapy of myocardial infarction

Myocardial infarction (MI) is a highly prevalent and lethal disease worldwide. Prevention and timely recovery are critical for the control of the recurrence and heart failure in MI survivors. The present study was designed to investigate the cardioprotective activity of the herbal medicine formula Baoyuan Decoction (BYD) and identify the active compounds and molecular targets. The ethanolic BYD extract (BYDE) was prepared by water extraction and ethanol precipitation of four herbal medicines, Astragali Radix, Ginseng Radix et Rhizoma, Cinnamomi Cortex, and Glycyrrhizae Radix et Rhizoma. Initially, BYDE was validated for the cardioprotective effectiveness in a mouse model of ischemia injury and rat cardiomyocyte H9C2 cells. As results, BYDE effectively reduced infarct size from 56% to 37% and preserved cardiac functions in mouse MI model while protected H9C2 cells against oxygen glucose deprivation. Subsequent network pharmacology analysis revealed that 122 bioactive ingredients, including flavonoids and saponins from the UPLC-MS/MS profile of BYDE, might target 37 MI-related proteins, including inflammatory and apoptotic mediators (e.g., TNF, NFKB1, CASPs, TNFRSF1A, CXCL12, BCL2A1). Pathway enrichment analysis suggested that BYDE might control the cardiac inflammation via targeting the tumor necrosis factor-alpha (TNF-α)/nuclear factor-κB (NF-κB) pathway while the selected targets were also implicated in IL-17 signaling pathway, lipid and atherosclerosis. Consequently, adenosine, ginsenoside Rh2, isoliquiritigenin, and licochalcone A were selected to generate the four-compound mixture AGILe and validated for the inhibitory effects on the TNF-α/NF-κB pathway. The results of the present study suggested that the mixture AGILe might be a potential cardioprotective remedy against MI.

Colon-specific delivery of isoliquiritigenin by oral edible zein/caseate nanocomplex for ulcerative colitis treatment

Although a natural anti-inflammatory ingredient, isoliquiritigenin (ISL), plays an effective role in ulcerative colitis (UC) treatment, a series of drawbacks still limit its clinical application, including the poor solubility, instability in gastrointestinal tract, and rapid elimination rate of ISL. Zein-based NPs display the benefits on drug loading and delivery, whereas with the poor stability. In this study, an edible nano-system composed by zein/caseinate complex was fabricated for the colon-targeting delivery of ISL, to improve its colon retention and anti-UC effects. The optimized ISL loaded zein/caseinate NPs (ISL@NPs) were prepared by single-factor design by anti-solvent precipitation method, and then characterized. The improved cellular uptake of ISL@NPs on NCM460 and RAW 264.7 cells was evaluated in vitro. The colon tissue permeability and retention capacity in vivo, and the anti-UC efficacy of ISL@NPs in DSS-induce UC were implemented. As a result, ISL@NPs with the high drug loading efficiency of 9.39% ± 0.26%, the average particle diameter of 137.32 ± 2.54 nm, exhibited the pH-sensitive stability in the different simulated gastrointestinal buffer. Compared with free ISL, ISL@NPs showed significantly higher cellular uptake ability in NCM460 and RAW 264.7 cells. Based on in vivo imaging system, zein/caseinate NPs showed the prolonged colonic retention and the enhanced penetration into the colonic epithelium. Finally, the oral administration of ISL@NPs could effectively alleviate the UC-related symptoms, down-regulate the production of pro-inflammatory factors, and reduce the infiltration of macrophages and neutrophils in colon tissues. In this study, an oral colon-specific nano-system, composed with the natural compound and edible materials, was developed as the promising alternatives in the prevention and treatment of UC.

Anti-inflammation of isoliquiritigenin via the inhibition of NF-κB and MAPK in LPS-stimulated MAC-T cells

Background

The application of plant extracts has received great interest for the treatment of bovine mastitis. Isoliquiritigenin (ISL) is a rich dietary flavonoid that has significant antioxidative, anti-inflammatory and anticancer activities. This study was conducted to explore the protective efficacy and related mechanism of ISL against lipopolysaccharide (LPS)-stimulated oxidation and inflammation in bovine mammary epithelial cells (MAC-T) by in vitro experiments.

Results

Real-time PCR and ELISA assays indicated that ISL treatment at 2.5, 5 and 10 μg/mL significantly reduced the mRNA and protein expression of the oxidative indicators cyclooxygenase-2 and inducible nitric oxide synthase (P < 0.01), and of the inflammatory cytokines interleukin-6 (P < 0.05), interleukin-1β (P < 0.01) and tumor necrosis factor-α (P < 0.01) in LPS-stimulated MAC-T cells. Moreover, Western blotting and immunofluorescence tests indicated that the phosphorylation levels of nuclear factor kappa (NF-κB) p65 and the inhibitor of NF-κB were significantly decreased by ISL treatment, thus blocking the nuclear transfer of NF-κB p65. In addition, ISL attenuated the phosphorylation levels of p38, extracellular signal-regulated kinase and c-jun NH2 terminal kinase.

Conclusions

Our data demonstrated that ISL downregulated the LPS-induced inflammatory response in MAC-T cells. The anti-inflammatory and antioxidative activity of ISL involves the NF-κB and MAPK cascades.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03414-1.

Impact of the Exposome on the Epigenome in Inflammatory Bowel Disease Patients and Animal Models

Inflammatory bowel diseases (IBD) are chronic inflammatory disorders of the gastrointestinal tract that encompass two main phenotypes, namely Crohn's disease and ulcerative colitis. These conditions occur in genetically predisposed individuals in response to environmental factors. Epigenetics, acting by DNA methylation, post-translational histones modifications or by non-coding RNAs, could explain how the exposome (or all environmental influences over the life course, from conception to death) could influence the gene expression to contribute to intestinal inflammation. We performed a scoping search using Medline to identify all the elements of the exposome that may play a role in intestinal inflammation through epigenetic modifications, as well as the underlying mechanisms. The environmental factors epigenetically influencing the occurrence of intestinal inflammation are the maternal lifestyle (mainly diet, the occurrence of infection during pregnancy and smoking); breastfeeding; microbiota; diet (including a low-fiber diet, high-fat diet and deficiency in micronutrients); smoking habits, vitamin D and drugs (e.g., IBD treatments, antibiotics and probiotics). Influenced by both microbiota and diet, short-chain fatty acids are gut microbiota-derived metabolites resulting from the anaerobic fermentation of non-digestible dietary fibers, playing an epigenetically mediated role in the integrity of the epithelial barrier and in the defense against invading microorganisms. Although the impact of some environmental factors has been identified, the exposome-induced epimutations in IBD remain a largely underexplored field. How these environmental exposures induce epigenetic modifications (in terms of duration, frequency and the timing at which they occur) and how other environmental factors associated with IBD modulate epigenetics deserve to be further investigated.

Wen Dan Tang: A Potential Jing Fang Decoction for Headache Disorders?

BACKGROUND

Chinese herbal medicine is considered relatively safe, inexpensive, and easily accessible. Wen Dan Tang (WDT), a Jing Fang ancient classical Chinese herbal formula with a broad indication profile has been used for several centuries in China to treat various illnesses.

QUESTION

Are there evidence-based clinical trials that show that WDT has a significant impact on the treatment of various diseases, especially in patients with migraine and tension-type headaches (TTH)?

METHODS

This study is based on an online database search using PubMed, Medline, Cochrane Library, AcuTrials, Embase, Semantic Scholar, Jstor, internet research, and review of ancient and modern Chinese medical textbooks regarding WDT and its compounds.

RESULTS

There were no studies on WDT in migraine and TTH; therefore, this work gathers and describes data for every single compound in the formula.

CONCLUSION

This study suggests that the bioactive compounds found in WDT composition show potential in treating patients with neurological, psychiatric disorders, cardiovascular diseases, metabolic syndrome, and digestive disorders. Some coherence between WDT in headache reduction and improvements in the quality of life in patients with migraines and TTH could be evaluated, showing positive results of WDT in these patients.

The In Vitro Anti-Inflammatory Activities of Galangin and Quercetin towards the LPS-Injured Rat Intestinal Epithelial (IEC-6) Cells as Affected by Heat Treatment

Flavonols possess several beneficial bioactivities in vitro and in vivo. In this study, two flavonols galangin and quercetin with or without heat treatment (100 °C for 15-30 min) were assessed for their anti-inflammatory activities in lipopolysaccharide (LPS)-stimulated rat intestinal epithelial (IEC-6) cells and whether the heat treatment caused activity changes. The flavonol dosages of 2.5-20 μmol/L had no cytotoxicity on the cells but could enhance cell viability (especially using 5 μmol/L flavonol dosage). The flavonols could decrease the production of prostaglandin E2 and three pro-inflammatory cytokines interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α, and simultaneously promote the production of two anti-inflammatory cytokines IL-10 and transforming growth factor-β. The Western-blot results verified that the flavonols could suppress the LPS-induced expression of TLR4 and phosphorylated IκBα and p65, while the molecular docking results also illustrated that the flavonols could bind with TLR4 and NF-κB to yield energy decreases of -(21.9-28.6) kJ/mol. Furthermore, an inhibitor BAY 11-7082 blocked the NF-κB signaling pathway by inhibiting the expression of phosphorylated IκBα/p65 and thus mediated the production of IL-6/IL-10 as the flavonols did, which confirmed the assessed anti-inflammatory effect of the flavonols. Consistently, galangin had higher anti-inflammatory activity than quercetin, while the heated flavonols (especially those with longer heat time) were less active than the unheated counterparts to exert these target anti-inflammatory effects. It is highlighted that the flavonols could antagonize the LPS-caused IEC-6 cells inflammation via suppressing TLR4/NF-κB activation, but heat treatment of the flavonols led to reduced anti-inflammatory efficacy.

Hyperbaric oxygen via mediating SIRT1-induced deacetylation of HMGB1 improved cReperfusion inj/reperfusion injury

Ischemic stroke leads to severe neurological dysfunction in adults. Hyperbaric oxygen (HBO) induces tolerance to cReperfusion inj/reperfusion (I/R) injury. Therefore, our aims were to investigate whether SIRT1 participates in regulatingin the neuro-protective effect of HBO in a cerebral I/R model and its mechanism. Mice N2a cells were used to construct an oxygen deprivation/reperfusion (OGD/R) model to simulate in vitro brain I/R injury and to evaluate the role of HBO in OGD/R stimulated cells. Cell proliferation was detected using MTT, and apoptosis was determined by flow cytometry. ELISA was used to measure the concentration of TNF-α, IL-1β and IL-6 related inflammatory factors. RT-qPCR and western blot assays were performed to test the expression of SIRT1. Immunoprecipitation was used to detect acetylation of HMGB1. Expression of SIRT1 was obviously reduced after OGD/R treatment in N2a cells, while SIRT1 was obviously enhanced in HBO treated cells. Moreover, knockdown of SIRT1 induced neuro-inflammation damage in cells and HBO effectively improved the inflammatory response in OGD/R treated cells by affecting SIRT1 levels. Furthermore, HBO induced the deacetylation of HMGB1 via regulating SIRT1. Interestingly, HBO via regulating the SIRT1-induced HMGB1 deacetylation and suppressing MMP-9 improved ischemic brain injury. HBO regulated ischemic brain injury via regulation of SIRT1-induced HMGB1 deacetylation, making it a potential treatment for ischemic brain injury treatment.

The potential of glycyrrhizin and licorice extract in combating COVID-19 and associated conditions

BACKGROUND

Several recent studies have stated that glycyrrhizin and licorice extract are present in most traditional Chinese medicine formulas used against SARS-CoV-2 in China. Significant data are showing that glycyrrhizin and licorice extract have multiple beneficial activities in combating most features of SARS-CoV-2.

PURPOSE

The aim of current review was to highlight recent progresses in research that showed the evidence of the potential use of glycyrrhizin and licorice extract against COVID-19.

METHODOLOGY

We have reviewed the information published from 1979 to October 2020. These studies demonstrated the effects , use and safety of glycyrrhizin and icorice extract against viral infections,bacterial infections, inflammatory disorders of lung ( in vitro and in vivo).  These studies were collated through online electronic databases research (Academic libraries as PubMed, Scopus, Web of Science and Egyptian Knowledge Bank).

RESULTS

Pooled effect size of articles provides information about the rationale for using glycyrrhizin and licorice extract to treat COVID-19. Fifty studies demonstrate antiviral activity of glycyrrhizin and licorice extract. The most frequent mechanism of the antiviral activity is due to disrupting viral uptake into the host cells and disrupting the interaction between receptor- binding domain (RBD) of SARS-COV2 and ACE2 in recent articles. Fifty studies indicate that glycyrrhizin and licorice extract have significant antioxidant, anti-inflammatory and immunomodulatory effects. Twenty five studies provide evidence for the protective effect of glycyrrhizin and licorice extract against inflammation-induced acute lung injury and cardiovascular disorders.

CONCLUSION

The current study showed several evidence regarding the beneficial effects of glycyrrhizin and licorice extract in combating COVID-19. More randomized clinical trials are needed to obtain a precise conclusion.

Valproic Acid Reduces Vasospasm through Modulation of Akt Phosphorylation and Attenuates Neuronal Apoptosis in Subarachnoid Hemorrhage Rats

Aneurysmal subarachnoid hemorrhage (SAH) is a devastating emergent event associated with high mortality and morbidity. Survivors usually experience functional neurological sequelae caused by vasospasm-related delayed ischemia. In this study, male Sprague-Dawley rats were randomly assigned to five groups: sham (non-SAH) group, SAH group, and three groups with SAH treated with different doses of valproic acid (VPA) (10, 20, 40 mg/kg, once-daily, for 7 days). The severity of vasospasm was determined by the ratio of cross-sectional areas to intima-media thickness of the basilar arteries (BA) on the seventh day after SAH. The BA showed decreased expression of phospho-Akt proteins. The dentate gyrus showed increased expression of cleaved caspase-3 and Bax proteins and decreased expression of Bcl-2, phospho-ERK 1/2, phospho-Akt and acetyl-histone H3 proteins. The incidence of SAH-induced vasospasm was significantly lower in the SAH group treated with VPA 40 mg/kg (p < 0.001). Moreover, all groups treated with VPA showed reversal of the above-mentioned protein expression in BA and the dentate gyrus. Treatment with VPA upregulated histone H3 acetylation and conferred anti-vasospastic and neuro-protective effects by enhancing Akt and/or ERK phosphorylation. This study demonstrated that VPA could alleviate delayed cerebral vasospasm induced neuro-apoptosis after SAH.

Class IIa HDAC Downregulation Contributes to Surgery-Induced Cognitive Impairment Through HMGB1-Mediated Inflammatory Response in the Hippocampi of Aged Mice

Objective

Perioperative neurocognitive disorders (PND) are a common complication in the elderly. Histone deacetylases (HDACs) are a class of enzymes that control the acetylation status of intracellular proteins. Thus, we explored whether HDACs trigger the release of high mobility group box 1 (HMGB1) through altering the acetylation status in the hippocampi of aged mice.

Materials and Methods

The effect of the Class IIa HDAC in PND was explored using an in vivo form of splenectomy. Sixteen-month-old healthy male C57BL/6J mice were randomly divided into five groups: control, anesthesia plus sham surgery, anesthesia plus splenectomy, LMK235 treatment, and PBS treatment. The hippocampi were harvested on either first, third, or seventh postoperative day. Cognitive function was assessed via a Morris water maze (MWM) test. Quantitative RT-PCR, Western blots and ELISAs were carried out to assess the targeted gene expression at transcriptional and translational levels.

Results

Splenectomy led to a significant deficiency in spatial memory acquisition, marked decreases in mRNA and protein levels of HDAC4 and HDAC5 in the hippocampus, and increases in the levels of total HMGB1 and acetylated HMGB1. In a similar fashion to splenectomy, treatment with the HDAC4/5 inhibitor LMK235 produced impaired spatial memory and an increase in the expression of HMGB1 and its acetylated counterpart in the hippocampus.

Conclusion

These results suggest that surgery leads to PND through class IIa HDAC downregulation-triggered HMGB1 release in hippocampus of aged mice. HDACs may be a potential therapeutic target for postoperative cognitive dysfunction.

Histone Deacetylases in the Inflamed Intestinal Epithelium-Promises of New Therapeutic Strategies

The intestinal epithelium is a complex, dynamic barrier that separates luminal contents from the immune compartment while mediating nutrient absorption and controlled passage of antigens to convey oral tolerance. A compromised epithelial barrier often leads to inflammation because immune cells in the lamina propria come into direct contact with luminal antigens. Defects in epithelial cell function were also shown to be involved in the etiology of inflammatory bowel diseases. These are severe, chronically relapsing inflammatory conditions of the gastrointestinal tract that also increase the risk of developing colorectal cancer. Despite major efforts of the scientific community, the precise causes and drivers of these conditions still remain largely obscured impeding the development of a permanent cure. Current therapeutic approaches mostly focus on alleviating symptoms by targeting immune cell signaling. The protein family of histone deacetylases (HDACs) has gained increasing attention over the last years, as HDAC inhibitors were shown to be potent tumor cell suppressors and also alleviate morbid inflammatory responses. Recent research continuously identifies new roles for specific HDACs suggesting that HDACs influence the cell signaling network from many different angles. This makes HDACs very interesting targets for therapeutic approaches but predicting effects after system manipulations can be difficult. In this review, we want to provide a comprehensive overview of current knowledge about the individual roles of HDACs in the intestinal epithelium to evaluate their therapeutic potential for inflammatory conditions of the gut.

Role of HMGB1 in Chemotherapy-Induced Peripheral Neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN), one of major dose-limiting side effects of first-line chemotherapeutic agents such as paclitaxel, oxaliplatin, vincristine, and bortezomib is resistant to most of existing medicines. The molecular mechanisms of CIPN have not been fully understood. High mobility group box 1 (HMGB1), a nuclear protein, is a damage-associated molecular pattern protein now considered to function as a pro-nociceptive mediator once released to the extracellular space. Most interestingly, HMGB1 plays a key role in the development of CIPN. Soluble thrombomodulin (TMα), known to degrade HMGB1 in a thrombin-dependent manner, prevents CIPN in rodents treated with paclitaxel, oxaliplatin, or vincristine and in patients with colorectal cancer undergoing oxaliplatin-based chemotherapy. In this review, we describe the role of HMGB1 and its upstream/downstream mechanisms in the development of CIPN and show drug candidates that inhibit the HMGB1 pathway, possibly useful for prevention of CIPN.

Isoliquiritigenin ameliorates caerulein-induced chronic pancreatitis by inhibiting the activation of PSCs and pancreatic infiltration of macrophages

Chronic pancreatitis (CP) is characterized by persistent inflammation of the pancreas that results in progressive loss of the endocrine and exocrine compartment owing to atrophy and/or replacement with fibrotic tissue. Currently, the clinical therapeutic scheme of CP is mainly symptomatic treatment including pancreatic enzyme replacement, glycaemic control and nutritional support therapy, lacking of specific therapeutic drugs for prevention and suppression of inflammation and fibrosis aggravating in CP. Here, we investigated the effect of isoliquiritigenin (ILG), a chalcone-type dietary compound derived from licorice, on pancreatic fibrosis and inflammation in a model of caerulein-induced murine CP, and the results indicated that ILG notably alleviated pancreatic fibrosis and infiltration of macrophages. Further in vitro studies in human pancreatic stellate cells (hPSCs) showed that ILG exerted significant inhibition on the proliferation and activation of hPSCs, which may be due to negative regulation of the ERK1/2 and JNK1/2 activities. Moreover, ILG significantly restrained the M1 polarization of macrophages (RAW 264.7) via attenuation of the NF-κB signalling pathway, whereas the M2 polarization was hardly affected. These findings indicated that ILG might be a potential anti-inflammatory and anti-fibrotic therapeutic agent for CP.

Differential Characteristics of HMGB2 Versus HMGB1 and their Perspectives in Ovary and Prostate Cancer

We have summarized common and differential functions of HMGB1 and HMGB2 proteins with reference to pathological processes, with a special focus on cancer. Currently, several "omic" approaches help us compare the relative expression of these 2 proteins in healthy and cancerous human specimens, as well as in a wide range of cancer-derived cell lines, or in fetal versus adult cells. Molecules that interfere with HMGB1 functions, though through different mechanisms, have been extensively tested as therapeutic agents in animal models in recent years, and their effects are summarized. The review concludes with a discussion on the perspectives of HMGB molecules as targets in prostate and ovarian cancers.

Salvianic acid A alleviates chronic alcoholic liver disease by inhibiting HMGB1 translocation via down-regulating BRD4

Alcoholic liver disease (ALD) is the major cause of chronic liver disease and a global health concern. ALD pathogenesis is initiated with liver steatosis, and ALD can progress to steatohepatitis, fibrosis, cirrhosis and even hepatocellular carcinoma. Salvianic acid A (SAA) is a phenolic acid component of Danshen, a Chinese herbal medicine with possible hepatoprotective properties. The purpose of this study was to investigate the effect of SAA on chronic alcoholic liver injury and its molecular mechanism. We found that SAA significantly inhibited alcohol‐induced liver injury and ameliorated ethanol‐induced hepatic inflammation. These protective effects of SAA were likely carried out through its suppression of the BRD4/HMGB1 signalling pathway, because SAA treatment largely diminished alcohol‐induced BRD4 expression and HMGB1 nuclear translocation and release. Importantly, BRD4 knockdown prevented ethanol‐induced HMGB1 release and inflammatory cytokine production in AML‐12 cells. Similarly, alcohol‐induced pro‐inflammatory cytokines were blocked by HMGB1 siRNA. Collectively, our results reveal that activation of the BRD4/HMGB1 pathway is involved in ALD pathogenesis. Therefore, manipulation of the BRD4/HMGB1 pathway through strategies such as SAA treatment holds great therapeutic potential for chronic alcoholic liver disease therapy.

Propofol Protects Lung Endothelial Barrier Function by Suppression of High-Mobility Group Box 1 (HMGB1) Release and Mitochondrial Oxidative Damage Catalyzed by HMGB1

Background

The processes of mechanical ventilation-induced lung injury (VILI) triggers the release of high-mobility group box 1 (HMGB1), a prominent damage-associated molecular pattern (DAMP) family member, which can cause damage to pulmonary vascular endothelial cells. We aimed to determine whether propofol protected against endothelial cell injury induced by HMGB1 in vitro and in vivo.

Material/Methods

ICR mice (male) were mechanically ventilated for 4 h after anesthetization at both low tidal volume (LVT, 6 ml/kg) and high tidal volume (HVT, 30 ml/kg). A propofol bolus (10 mg/kg) was administered to the animals prior to the onset of ventilation, followed by infusion at 5 mg/(kg·h). We obtained confluent cultures of mouse lung vascular endothelial cells (MLVECs) and then performed cyclic stretching at 20% stretch for 4 h with or without propofol.

Results

HMGB1 reduced the expression of tight junctions between endothelial cells, including VE-cadherin and ZO-1, and increased endothelial permeability, and both were blocked by propofol. We found that MLVECs exhibited mitochondrial oxidative damage by HMGB1, which was successfully suppressed through administration of MnTBAP as well as propofol. Propofol ameliorated HVT-associated lung vascular hyperpermeability and HMGB1 production in vivo. Propofol also inhibited HMBG1 release caused by cyclic stretching in MLVECs in vitro.

Conclusions

Our results prove that the cyto-protective function of propofol protects against lung ventilation-induced dysfunction of the lung endothelial barrier. This function of propofol is mediated through inhibition of HMGB1 release caused by mechanical stretching and mitochondrial oxidative damage triggered by HMGB1.

Regulation of Acetylation in High Mobility Group Protein B1 Cytosol Translocation

High mobility group protein B1 (HMGB1) is a nonhistone that mainly binds to nucleus DNA. As an important late inflammatory transmitter, extracellular HMGB1 is involved in the inflammatory immune response, tumor growth, infiltration, and metastasis. HMGB1 is actively released by activated inflammatory cells or passively released by necrotic cells. Then the released extracellular HMGB1 further induces monocytes/macrophages, neutrophils, and dendritic cells to secrete inflammatory cytokines. Therefore, HMGB1 can not only act as a proinflammatory factor to directly involve in tissue damage, but also acts as an inflammatory medium to aggravate the inflammatory cascade reaction. Studies have shown that the post-translational modification (PTM) participated in the process of HMGB1 cytosol translocation and extracellular release. The acetylation modification is the most common PTM for localization sequence of HMGB1, and the affinity of HMGB1 to DNA depends on the degree of acetylation for HMGB1. The acetylation can weaken the binding of HMGB1 to DNA, which means less HMGB1 cytosol translocation and extracellular release. This article reviews the acetylation regulation mechanisms of cytosol translocation and extracellular release of HMGB1 and provides a therapeutic strategy for controlling HMGB1-induced inflammatory responses in the future.

Degradation of histone deacetylase 4 via the TLR4/JAK/STAT1 signaling pathway promotes the acetylation of high mobility group box 1 (HMGB1) in lipopolysaccharide-activated macrophages

High mobility group box 1 (HMGB1) has been proposed as crucial in the pathogenesis of many diseases including sepsis. Acetylation of HMGB1 prevents its entry into the nucleus and leads to its secretion from the cell where it can trigger inflammation. We hypothesized that histone deacetylase 4 (HDAC4) controls the acetylation of HMGB1 in lipopolysaccharide (LPS)‐stimulated RAW264.7 cells via the janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway. The results showed that LPS treatment promoted the degradation of HDAC4 in a proteasome‐dependent manner, which led to HMGB1 acetylation. In LPS‐activated RAW264.7 cells, treatment with TAK‐242 (a toll like receptor 4 inhibitor) and pyridone 6 (a JAK inhibitor) significantly inhibited HDAC4 degradation and acetylation of HMGB1, and thus prevented secretion of HMGB1. Decreased phosphorylation of STAT1 was also observed. Interestingly, HDAC4 overexpression significantly prevented the acetylation and secretion of HMGB1 in both RAW264.7 cells and isolated murine peritoneal macrophages. We conclude that HDAC4 might be a useful target for the treatment of sepsis.

Valproic acid attenuates traumatic spinal cord injury-induced inflammation via STAT1 and NF-κB pathway dependent of HDAC3

BACKGROUND

Microglial polarization with M1/M2 phenotype shifts and the subsequent neuroinflammatory responses are vital contributing factors for spinal cord injury (SCI)-induced secondary injury. Nuclear factor-κB (NF-κB) is considered the central transcription factor of inflammatory mediators, which plays a crucial role in microglial activation. Lysine acetylation of STAT1 seems necessary for NF-kB pathway activity, as it is regulated by histone deacetylases (HDACs). There have been no studies that have explained if HDAC inhibition by valproic acid (VPA) affects the NF-κB pathway via acetylation of STAT1 dependent of HDAC activity in the microglia-mediated central inflammation following SCI. We investigated the potential molecular mechanisms that focus on the phenotypic transition of microglia and the STAT1-mediated NF-κB acetylation after a VPA treatment.

METHODS

The Basso-Beattie-Bresnahan locomotion scale, the inclined plane test, the blood-spinal cord barrier, and Nissl staining were employed to determine the neuroprotective effects of VPA treatment after SCI. Assessment of microglia polarization and pro-inflammatory markers, such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and interferon (INF)-γ was used to evaluate the neuroinflammatory responses and the anti-inflammatory effects of VPA treatment. Immunofluorescent staining and Western blot analysis were used to detect HDAC3 nuclear translocation, activity, and NF-κB signaling pathway activation to evaluate the effects of VPA treatment. The impact of STAT1 acetylation on NF-kB pathway and the interaction between STAT1 and NF-kB were assessed to evaluate anti-inflammation effects of VPA treatment and also whether these effects were dependent on a STAT1/NF-κB pathway to gain further insight into the mechanisms underlying the development of the neuroinflammatory response after SCI.

RESULTS

The results showed that the VPA treatment promoted the phenotypic shift of microglia from M1 to M2 phenotype and inhibited microglial activation, thus reducing the SCI-induced inflammatory factors. The VPA treatment upregulation of the acetylation of STAT1/NF-κB pathway was likely caused by the HDAC3 translocation to the nucleus and activity. These results indicated that the treatment with the VPA suppressed the expression and the activity of HDAC3 and enhanced STAT1, as well as NF-κB p65 acetylation following a SCI. The acetylation status of NF-kB p65 and the complex with NF-κB p65 and STAT1 inhibited the NF-kB p65 transcriptional activity and attenuated the microglia-mediated central inflammatory response following SCI.

CONCLUSIONS

These results suggested that the VPA treatment attenuated the inflammatory response by modulating microglia polarization through STAT1-mediated acetylation of the NF-κB pathway, dependent of HDAC3 activity. These effects led to neuroprotective effects following SCI.

Anti-pseudo-allergy effect of isoliquiritigenin is MRGPRX2-dependent

Mast cell (MC) is the key mediate during allergy accours. The classical MC degranulation pathway is mediated by FcεRI aggregation and varies in strength among subjects, whereas a non-classical but analogous pseudo-allergic way was recently reported to occur via MRGPRX2. However, few therapies can directly target pseudo-allergies and related Mrgprs. Isoliquiritigenin (ISL) exerts anti-inflammatory effect in many diseases. In this study, we investigated the anti-pseudo-allergy effects of ISL and its underlying mechanism. We first examined the effect of ISL on the IgE-independent response using a PCA model,and in vitro cultured MCs. Further, we evaluated whether the anti-pseudo-allergic effect was related to Mrgprs using in vitro MRGPRX2-expressing HEK293 cells. ISL dose-dependently suppressed compound 48/80 (C48/80)-induced PCA and MC degranulation in mice. Our in vitro studies revealed that ISL reduced C48/80-induced calcium flux and suppressed degranulation in LAD2 cells. ISL dose dependently inhibited C48/80-induced MRGPRX2-expressing HEK293 cell activation. Our finding that ISL could inhibit IgE-independent allergy, via the Mrgprx2 pathway provides a new insight into pseudo-allergy and its therapy.

Omega-3 polyunsaturated fatty acid attenuates the inflammatory response by modulating microglia polarization through SIRT1-mediated deacetylation of the HMGB1/NF-κB pathway following experimental traumatic brain injury

Background

Microglial polarization and the subsequent neuroinflammatory response are contributing factors for traumatic brain injury (TBI)-induced secondary injury. High mobile group box 1 (HMGB1) mediates the activation of the NF-κB pathway, and it is considered to be pivotal in the late neuroinflammatory response. Activation of the HMGB1/NF-κB pathway is closely related to HMGB1 acetylation, which is regulated by the sirtuin (SIRT) family of proteins. Omega-3 polyunsaturated fatty acids (ω-3 PUFA) are known to have antioxidative and anti-inflammatory effects. We previously demonstrated that ω-3 PUFA inhibited TBI-induced microglial activation and the subsequent neuroinflammatory response by regulating the HMGB1/NF-κB signaling pathway. However, no studies have elucidated if ω-3 PUFA affects the HMGB1/NF-κB pathway in a HMGB1 deacetylation of dependent SIRT1 manner, thus regulating microglial polarization and the subsequent neuroinflammatory response.

Methods

The Feeney DM TBI model was adopted to induce brain injury in rats. Modified neurological severity scores, rotarod test, brain water content, and Nissl staining were employed to determine the neuroprotective effects of ω-3 PUFA supplementation. Assessment of microglia polarization and pro-inflammatory markers, such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and HMGB1, were used to evaluate the neuroinflammatory responses and the anti-inflammatory effects of ω-3 PUFA supplementation. Immunofluorescent staining and western blot analysis were used to detect HMGB1 nuclear translocation, secretion, and HMGB1/NF-κB signaling pathway activation to evaluate the effects of ω-3 PUFA supplementation. The impact of SIRT1 deacetylase activity on HMGB1 acetylation and the interaction between HMGB1 and SIRT1 were assessed to evaluate anti-inflammation effects of ω-3 PUFAs, and also, whether these effects were dependent on a SIRT1-HMGB1/NF-κB axis to gain further insight into the mechanisms underlying the development of the neuroinflammatory response after TBI.

Results

The results of our study showed that ω-3 PUFA supplementation promoted a shift from the M1 microglial phenotype to the M2 microglial phenotype and inhibited microglial activation, thus reducing TBI-induced inflammatory factors. In addition, ω-3 PUFA-mediated downregulation of HMGB1 acetylation and its extracellular secretion was found to be likely due to increased SIRT1 activity. We also found that treatment with ω-3 PUFA inhibited HMGB1 acetylation and induced direct interactions between SIRT1 and HMGB1 by elevating SIRT1 activity following TBI. These events lead to inhibition of HMGB1 nucleocytoplasmic translocation/extracellular secretion and alleviated HMGB1-mediated activation of the NF-κB pathway following TBI-induced microglial activation, thus inhibiting the subsequent inflammatory response.

Conclusions

The results of this study suggest that ω-3 PUFA supplementation attenuates the inflammatory response by modulating microglial polarization through SIRT1-mediated deacetylation of the HMGB1/NF-κB pathway, leading to neuroprotective effects following experimental traumatic brain injury.

Omega-3 polyunsaturated fatty acid supplementation attenuates microglial-induced inflammation by inhibiting the HMGB1/TLR4/NF-κB pathway following experimental traumatic brain injury

Background

Microglial activation and the subsequent inflammatory response in the central nervous system play important roles in secondary damage after traumatic brain injury (TBI). High-mobility group box 1 (HMGB1) protein, an important mediator in late inflammatory responses, interacts with transmembrane receptor for advanced glycation end products (RAGE) and toll-like receptors (TLRs) to activate downstream signaling pathways, such as the nuclear factor (NF)-κB signaling pathway, leading to a cascade amplification of inflammatory responses, which are related to neuronal damage after TBI. Omega-3 polyunsaturated fatty acid (ω-3 PUFA) is a commonly used clinical immunonutrient, which has antioxidative and anti-inflammatory effects. However, the effects of ω-3 PUFA on HMGB1 expression and HMGB1-mediated activation of the TLR4/NF-κB signaling pathway are not clear.

Methods

The Feeney DM TBI model was adopted to induce brain injury in rats. Modified neurological severity scores, brain water content, and Nissl staining were employed to determine the neuroprotective effects of ω-3 PUFA supplementation. Assessment of microglial activation in lesioned sites and protein markers for proinflammatory, such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, interferon (IFN)-γ, and HMGB1 were used to evaluate neuroinflammatory responses and anti-inflammation effects of ω-3 PUFA supplementation. Immunofluorescent staining and western blot analysis were used to detect HMGB1 nuclear translocation, secretion, and HMGB1-mediated activation of the TLR4/NF-κB signaling pathway to evaluate the effects of ω-3 PUFA supplementation and gain further insight into the mechanisms underlying the development of the neuroinflammatory response after TBI.

Results

It was found that ω-3 PUFA supplementation inhibited TBI-induced microglial activation and expression of inflammatory factors (TNF-α, IL-1β, IL-6, and IFN-γ), reduced brain edema, decreased neuronal apoptosis, and improved neurological functions after TBI. We further demonstrated that ω-3 PUFA supplementation inhibited HMGB1 nuclear translocation and secretion and decreased expression of HMGB1 in neurons and microglia in the lesioned areas. Moreover, ω-3 PUFA supplementation inhibited microglial activation and the subsequent inflammatory response by regulating HMGB1 and the TLR4/NF-κB signaling pathway.

Conclusions

The results of this study suggest that microglial activation and the subsequent neuroinflammatory response as well as the related HMGB1/TLR4/NF-κB signaling pathway play essential roles in secondary injury after TBI. Furthermore, ω-3 PUFA supplementation inhibited TBI-induced microglial activation and the subsequent inflammatory response by regulating HMGB1 nuclear translocation and secretion and also HMGB1-mediated activation of the TLR4/NF-κB signaling pathway, leading to neuroprotective effects.