Role of histone deacetylases and sirtuins in the ischaemic stroke: a protocol for a systematic review and meta-analysis of animal studies

BACKGROUND

Stroke is a major cause of global mortality and disability. Currently, the treatment of acute ischaemic stroke through reperfusion has posed several challenges, raising the need for complementary options to protect the ischaemic penumbra. Recent investigations have indicated that certain epigenetic factors, specifically, histone deacetylases (HDACs) and sirtuins, can be promising for ischaemic stroke therapy, with recent studies suggesting that inhibitors of HDACs or sirtuins may provide neuronal protection after ischaemic stroke. However, the impact of specific HDAC/sirtuin isoforms on the survival of neuronal cells following stroke is still uncertain. This study aims to provide a comprehensive overview of the function of HDACs and their modulators in the treatment of acute ischaemic stroke.

METHODS

This systematic review and meta-analysis will encompass animal intervention studies that explore the efficacy of modulation of HDACs and sirtuins in the acute phase of ischaemic stroke. The review will be reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Electronic searches will be conducted in PubMed, Web of Science and Scopus, with subsequent screening by independent reviewers based on the established eligibility criteria. Methodological quality will be evaluated using the SYRCLE risk of bias tool. The primary outcomes will be infarct volume and functional response, with the secondary outcomes established a priori. Data pertaining to infarct volume will be used for random-effects meta-analysis. Additionally, a descriptive summary will be conducted for the functional response and secondary outcomes.

DISCUSSION

No systematic review and meta-analysis on the treatment of ischaemic stroke through HDAC modulation has been conducted to date. A comprehensive analysis of the available literature on the relevant preclinical investigations can yield invaluable insights in discerning the most effective trials and in further standardisation of preclinical studies.

SYSTEMATIC REVIEW REGISTRATION

This systematic review has been recorded in the International Prospective Register of Systematic Reviews (PROSPERO), with the assigned reference number: CRD42023381420.

In-Silico Analysis of Chromatin Modifiers and Profiling of Histone Deacetylases (HDAC's) in Human Oral Cancer

Histone modifications have been demonstrated to play a significant role in oral squamous cell carcinoma (OSCC) epigenetic regulation. An in-silico analysis of The Cancer Genome Atlas (TCGA) of various histone acetyl transferases (HATs) and histone deacetylases (HDACs) suggested that HATs do not differ between normal and tumor samples whereas HDAC2 and HDAC1 change maximally and marginally respectively between normal and tumor patients with no change being noted in HDAC6 expression. Hence, this investigation was carried out to validate the expression states of HDAC 1, 2 and 6 mRNAs in buccal mucosa and tongue SCC samples in an Indian cohort. Buccal mucosa and tongue squamous cell carcinoma tissues with intact histopathology were processed for RNA isolation followed by cDNA synthesis which was then subjected to q-PCR for HDACs. The average RNA yield of the tongue tissue sample was ∼2 µg/mg of tissue and the A_260/280 ratios were between 2.03 and 2.06. The average RNA yield of buccal mucosa tissue sample was ∼1 µg/mg of tissue and the A_260/280 ratio were between 2.00 and 2.08. We have demonstrated that HDAC2 was overexpressed in tongue and buccal mucosa samples. Over-expression of HDAC2 imply potential use of HDACi along with standard chemotherapeutic drug in oral cancer treatment.

Comparison of Epigenetic Modifier Genes in Bovine Adipose Tissue-Derived Stem Cell Based Embryos, as Donors, with In Vitro and Parthenogenesis Embryos

Objective

Regarding that undifferentiated mesenchymal stem cells, as donor cells, require less epigenetic reprogramming, possibility of using bovine adipose tissue-derived stem cells (BASCs) with low level of DNMTs and HDACs expression was evaluated.

Materials and Methods

In this experimental study, we examined gene expression of epigenetic modifiers including DNA methyltransferases (DNMT1, DNMT3A and DNMT3B) and histone deacetylases (HDAC1-3), as well as protein levels of histone H3 acetylation at lysine 9 (H3K9ac) and POU5F1 (also known as OCT4) at two stages of preimplantation development among in vitro fertilization (IVF), parthenogenetic activation (PA) and somatic cell nuclear transfer (SCNT) groups.

Results

The results revealed that developmental competence of IVF embryos was higher than SCNT embryos (P<0.05). In the PA and SCNT groups, DNMT1, HDAC2 and HDAC3 mRNA were overexpressed (P<0.05), and proteins levels of H3K9ac and POU5F1 were reduced at 6-8 cells and blastocyst stages compared to IVF (P<0.05). The mRNA expression of DNMT1 an<0.05) in both developmental stages (except HDAC1 in blastocyst stage).

Conclusion

The SCNT embryos derived from BASCs have endured considerable nuclear reprogramming during early embryo development. Comparison of PA and SCNT blastocysts demonstrated that HDAC1 and DNMT1 may attribute to developmental competence variability of bovine embryos.

Effects of Macrolide and Corticosteroid in Neutrophilic Asthma Mouse Model

BACKGROUND

Asthma is a disease of chronic airway inflammation with heterogeneous features. Neutrophilic asthma is corticosteroid-insensitive asthma related to absence or suppression of TH2 process and increased TH1 and/or TH17 process. Macrolides are immunomodulatory drug that reduce airway inflammation, but their role in asthma is not fully known. The purpose of this study was to evaluate the role of macrolides in neutrophilic asthma and compare their effects with those of corticosteroids.

METHODS

C57BL/6 female mice were sensitized with ovalbumin (OVA) and lipopolysaccharides (LPS). Clarithromycin (CAM) and/or dexamethasone (DXM) were administered at days 14, 15, 21, 22, and 23. At day 24, the mice were sacrificed.

RESULTS

Airway resistance in the OVA+LPS exposed mice was elevated but was more attenuated after treatment with CAM+DXM compared with the monotherapy group (p<0.05 and p<0.01). In bronchoalveolar lavage fluid study, total cells and neutrophil counts in OVA+LPS mice were elevated but decreased after CAM+DXM treatment. In hematoxylin and eosin stain, the CAM+DXM-treated group showed less inflammation additively than the monotherapy group. There was less total protein, interleukin 17 (IL-17), interferon γ, and tumor necrosis factor α in the CAM+DXM group than in the monotherapy group (p<0.001, p<0.05, and p<0.001). More histone deacetylase 2 (HDAC2) activity was recovered in the DXM and CAM+DXM challenged groups than in the control group (p<0.05).

CONCLUSION

Decreased IL-17 and recovered relative HDAC2 activity correlated with airway resistance and inflammation in a neutrophilic asthma mouse model. This result suggests macrolides as a potential corticosteroid-sparing agent in neutrophilic asthma.

Epigenetic Interactions between Alcohol and Cannabinergic Effects: Focus on Histone Modification and DNA Methylation

Epigenetic studies have led to a more profound understanding of the mechanisms involved in chronic conditions. In the case of alcohol addiction, according to the National Institute on Alcohol Abuse and Alcoholism, 16 million adults suffer from Alcohol Use Disorders (AUDs). Even though therapeutic interventions like behavioral therapy and medications to prevent relapse are currently available, no robust cure exists, which stems from the lack of understanding the mechanisms of action of alcohol and the lack of development of precision medicine approaches to treat AUDs. Another common group of addictive substance, cannabinoids, have been studied extensively to reveal they work through cannabinoid receptors. Therapeutic applications have been found for the cannabinoids and a deeper understanding of the endocannabinoid system has been gained over the years. Recent reports of cannabinergic mechanisms in AUDs has opened an exciting realm of research that seeks to elucidate the molecular mechanisms of alcohol-induced end organ diseases and hopefully provide insight into new therapeutic strategies for the treatment of AUDs. To date, several epigenetic mechanisms have been associated with alcohol and cannabinoids independently. Therefore, the scope of this review is to compile the most recent literature regarding alcohol and cannabinoids in terms of a possible epigenetic connection between the endocannabinoid system and alcohol effects. First, we will provide an overview of epigenetics, followed by an overview of alcohol and epigenetic mechanisms with an emphasis on histone modifications and DNA methylations. Then, we will provide an overview of cannabinoids and epigenetic mechanisms. Lastly, we will discuss evidence of interactions between alcohol and cannabinergic pathways and possible insights into the novel epigenetic mechanisms underlying alcohol-cannabinergic pathway activity. Finalizing the review will be a discussion of future directions and therapeutic applications.

Histone Deacetylases and Their Regulatory MicroRNAs in Hepatocarcinogenesis

A growing body of evidence suggests that epigenetic modifications are promising potential mechanisms in cancer research. Among the molecules that mediate epigenetic mechanisms, histone deacetylases (HDACs) are critical regulators of gene expression that promote formation of heterochromatin by deacetylating histone and non-histone proteins. Aberrant regulation of HDACs contributes to malignant transformation and progression in a wide variety of human cancers, including hepatocellular carcinoma (HCC), gastric cancer, lung cancer, and other cancers. Thus, the roles of HDACs have been extensively studied because of their potential as therapeutic targets. However, the underlying mechanism leading to deregulation of individual HDACs remains largely unknown. Some reports have suggested that functional microRNAs (miRNAs) modulate epigenetic effector molecules including HDACs. Here, we describe the oncogenic or tumor suppressive functions of HDAC families and their regulatory miRNAs governing HDAC expression in hepatocarcinogenesis.

Histone Deacetylase Gene Expression Following Binge Alcohol Consumption in Rats and Humans

BACKGROUND

Alcohol binge drinking is one of the most common patterns of excessive alcohol use and recent data would suggest that histone deacetylases (HDACs) gene expression profiling could be useful as a biomarker for psychiatric disorders.

METHODS

This study aimed to characterize the gene expression patterns of Hdac 1-11 in samples of rat peripheral blood, liver, heart, prefrontal cortex, and amygdala following repeated binge alcohol consumption and to determine the parallelism of Hdac gene expression between rats and humans in peripheral blood. To accomplish this goal, we examined Hdac gene expression following 1, 4, or 8 alcohol binges (3 g/kg, orally) in the rat, in patients who were admitted to the hospital emergency department for acute alcohol intoxication, and in rats trained in daily operant alcohol self-administration.

RESULTS

We primarily found that acute alcohol binging reduced gene expression (Hdac1-10) in the peripheral blood of alcohol-naïve rats and that this effect was attenuated following repeated alcohol binges. There was also a reduction of Hdac gene expression in the liver (Hdac2,4,5), whereas there was increased expression in the heart (Hdac1,7,8) and amygdala (Hdac1,2,5). Additionally, increased blood alcohol concentrations were measured in rat blood at 1 to 4 hours following repeated alcohol binging, and the only group that developed hepatic steotosis (fatty liver) were those animals exposed to 8 alcohol binge events. Finally, both binge consumption of alcohol in humans and daily operant alcohol self-administration in rats increased Hdac gene expression in peripheral blood.

CONCLUSIONS

Our results suggest that increases in HDAC gene expression within the peripheral blood are associated with chronic alcohol consumption, whereas HDAC gene expression is reduced following initial exposure to alcohol.

Antiallergic Effects of Trichostatin A in a Murine Model of Allergic Rhinitis

Objectives

Trichostatin A (TSA), an inhibitor of histone deacetylase, has been shown to play an important role in attenuating asthmatic inflammation. However, the effect of TSA in allergic rhinitis is not known. The aims of this study were to investigate the effect of TSA on allergic nasal inflammation and on the induction of regulatory T cells in a murine model of allergic rhinitis.

Methods

BALB/c mice were sensitized intraperitoneally with ovalbumin (OVA) and then challenged intranasally with OVA. TSA (1 mg/kg) was given to the treatment group, and multiple parameters of allergic responses were evaluated to determine the effects of TSA on allergic rhinitis. Allergic nasal symptom scores, including frequency of rubbing and sneezing, were checked. Eosinophil infiltrations were stained with Chromotrope 2R, and the expression levels of OVA-specific IgE, T-helper 1 (Th1) cytokine (interferon-gamma [IFN-γ]), Th2 cytokines (interleukin [IL] 4 and IL-5) and Treg (Foxp3, IL-10, and transforming growth factor-beta [TGF-β]) were measured by quantitative reverse transcription-polymerase chain reaction or enzyme-linked immunosorbent assay.

Results

TSA reduced the scores of allergic nasal symptoms and the amount of eosinophil infiltration into the nasal mucosa. TSA suppressed OVA-specific IgE levels and reduced expression of the IL-4 and IL-5. However, the expression of IFN-γ was unchanged in the treatment group. The levels of Foxp3, IL-10, and TGF-β were increased in pretreatment with TSA as compared to control group.

Conclusion

This study shows that TSA induced antiallergic effects by decreasing eosinophilic infiltration and Th2 cytokines in a murine model of allergic rhinitis via regulation of Tregs. Thus, TSA may be considered a potentially therapeutic agent in treating allergic rhinitis.