Histone deacetylase inhibitors decrease the antigen presenting activity of murine bone marrow derived dendritic cells

A COMPARATIVE ANALYSIS TO DETERMINE THE OPTIMUM HISTONE DEACETYLASE INHIBITORS AND ADMINISTRATION ROUTE FOR IMPROVING SURVIVAL AND ORGAN INJURY IN RATS AFTER HEMORRHAGIC SHOCK

ABSTRACT

Objective: Histone deacetylase inhibitors (HDACIs) have been reported to improve survival in rats with hemorrhagic shock (HS). However, no consensus exists on the most effective HDACIs and their administration routes. We herein aimed to determine the optimal HDACIs and administration route in rats with HS. Methods: Survival analysis: In experiment I, male Sprague-Dawley rats were subjected to HS (mean arterial pressure [MAP] was maintained at 30-40 mm Hg for 20 min), and intravenously injected with the following agents (n = 8 per group): (1) no treatment, (2) vehicle (VEH), (3) entinostat (MS-275), (4) [ N -((6-(Hydroxyamino)-6-oxohexyl)oxy)-3,5-dimethylbenzamide] (LMK-235), (5) tubastatin A, (6) trichostatin A (TSA), and (7) sirtinol. In experiment II, rats were intraperitoneally injected with TSA. Mechanism research: In experiments I and II, rats were observed for 3 h, after which blood samples and liver, heart, and lung tissues were harvested. Results: In experiment I, 75% rats in the VEH group but only 25% rats in the LMK-235 and sirtinol groups died within ≤5 h of treatment, whereas the survival of rats in the MS-275, tubastatin A, and TSA groups was significantly prolonged. MS-275, LMK-235, tubastatin A, and TSA significantly reduced histopathological scores, apoptosis cell numbers, and inflammatory cytokine levels. In experiment II, the survival was longer after i.v. TSA treatment than after i.p. TSA treatment, and the IL-6 levels in the heart were significantly lower in rat who received i.p. TSA treatment than in those who received i.v. TSA treatment. Conclusions: The i.v. effect was superior to the i.p. effect, while nonselective and isoform-specific classes I and IIb HDACIs had similar effects.

Epigenetic Modulation of TLR4 Expression by Sulforaphane Increases Anti-Inflammatory Capacity in Porcine Monocyte-Derived Dendritic Cells

Simple Summary

Epigenetic modifications of the genes regulate the inflammation process that includes the DNA methylation and histone acetylation. Sulforaphane is well known for its immunomodulatory properties. Notably, the mechanism of its anti-inflammatory functions involving epigenetic modifications is unclear. This study highlighted the regulatory mechanism of sulforaphane in the innate immunity responses in an acute inflammatory state employ in vivo cell culture model. Porcine monocyte-derived dendritic cells were exposed to LPS with or without sulforaphane pre-treatment for these purposes. Epigenetics modulations of the important genes and regulatory factors were studies as well as the immune responses of the cells were vigorously studied over the period of time. This study deciphers the mechanism of SFN in restricting the excessive inflammatory reactions, thereby, exerting its protective and anti-inflammatory function though epigenetic mechanism.

Abstract

Inflammation is regulated by epigenetic modifications, including DNA methylation and histone acetylation. Sulforaphane (SFN), a histone deacetylase (HDAC) inhibitor, is also a potent immunomodulatory agent, but its anti-inflammatory functions through epigenetic modifications remain unclear. Therefore, this study aimed to investigate the epigenetic effects of SFN in maintaining the immunomodulatory homeostasis of innate immunity during acute inflammation. For this purpose, SFN-induced epigenetic changes and expression levels of immune-related genes in response to lipopolysaccharide (LPS) stimulation of monocyte-derived dendritic cells (moDCs) were analyzed. These results demonstrated that SFN inhibited HDAC activity and caused histone H3 and H4 acetylation. SFN treatment also induced DNA demethylation in the promoter region of the MHC-SLA1 gene, resulting in the upregulation of Toll-like receptor 4 (TLR4), MHC-SLA1, and inflammatory cytokines’ expression at 6 h of LPS stimulation. Moreover, the protein levels of cytokines in the cell culture supernatants were significantly inhibited by SFN pre-treatment followed by LPS stimulation in a time-dependent manner, suggesting that inhibition of HDAC activity and DNA methylation by SFN may restrict the excessive inflammatory cytokine availability in the extracellular environment. We postulate that SFN may exert a protective and anti-inflammatory function by epigenetically influencing signaling pathways in experimental conditions employing porcine moDCs.

Immunomodulatory Effects of Histone Deacetylation Inhibitors in Graft-vs.-Host Disease After Allogeneic Stem Cell Transplantation

Histone deacetylase inhibitors are currently the most studied drugs because of their beneficial effects on inflammatory response. Emerging data from numerous basic studies and clinical trials have shown that histone deacetylase inhibitors can suppress immune-mediated diseases, such as graft-vs.-host disease (GVHD), while retaining beneficial graft-vs.-leukemia (GVL) effects. These drugs prevent and/or treat GVHD by modifying gene expression and inhibiting the production of proinflammatory cytokines, regulating the function of alloreactive T cells, and upregulating the function and number of regulatory T cells. Some of these drugs may become new immunotherapies for GVHD and other immune diseases.

Novel biomolecule lycopene-reduced graphene oxide-silver nanoparticle enhances apoptotic potential of trichostatin A in human ovarian cancer cells (SKOV3)

Background

Recently, there has been much interest in the field of nanomedicine to improve prevention, diagnosis, and treatment. Combination therapy seems to be most effective when two different molecules that work by different mechanisms are combined at low dose, thereby decreasing the possibility of drug resistance and occurrence of unbearable side effects. Based on this consideration, the study was designed to investigate the combination effect of reduced graphene oxide-silver nanoparticles (rGO-AgNPs) and trichostatin A (TSA) in human ovarian cancer cells (SKOV3).

Methods

The rGO-AgNPs were synthesized using a biomolecule called lycopene, and the resultant product was characterized by various analytical techniques. The combination effect of rGO-Ag and TSA was investigated in SKOV3 cells using various cellular assays such as cell viability, cytotoxicity, and immunofluorescence analysis.

Results

AgNPs were uniformly distributed on the surface of graphene sheet with an average size between 10 and 50 nm. rGO-Ag and TSA were found to inhibit cell viability in a dose-dependent manner. The combination of rGO-Ag and TSA at low concentration showed a significant effect on cell viability, and increased cytotoxicity by increasing the level of malondialdehyde and decreasing the level of glutathione, and also causing mitochondrial dysfunction. Furthermore, the combination of rGO-Ag and TSA had a more pronounced effect on DNA fragmentation and double-strand breaks, and eventually induced apoptosis.

Conclusion

This study is the first to report that the combination of rGO-Ag and TSA can cause potential cytotoxicity and also induce significantly greater cell death compared to either rGO-Ag alone or TSA alone in SKOV3 cells by various mechanisms including reactive oxygen species generation, mitochondrial dysfunction, and DNA damage. Therefore, this combination chemotherapy could be possibly used in advanced cancers that are not suitable for radiation therapy or surgical treatment and facilitate overcoming tumor resistance and disease progression.

Histone deacetylase inhibitors suppress immature dendritic cell's migration by regulating CC chemokine receptor 1 expression

The modulation of immature dendritic cells (iDCs), which involves processes such as phagocytosis, migration, and maturation, is considered a beneficial research theme. Once activated by an antigen, iDCs turn to mature DCs (mDCs) and migrate towards secondary lymphoid organs, and initiate the progress of cellular immunity. Histone deacetylase inhibitors (HDACis) are also thought to be a major modulator of cellular immunity. Herein, we demonstrate that HDACis (trichostatin-A (TSA), sodium butylate (SB), scriptaid (ST)) play a central regulatory role in the migratory activity of iDCs. In our results, TSA, SB and ST showed the potent inhibitory effect on the migration of iDCs stimulated by MIP-1α. The inhibitory activities of HDACis were found to be caused by reduction of CCR1 expression on the cell surface, and by the inhibition of phosphorylation of p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinases 1 and 2 (ERK 1/2), and c-Jun N-terminal kinase (JNK).

Tumor suppressor maspin as a modulator of host immune response to cancer

Despite the promising clinical outcome, the primary challenge of the curative cancer immunotherapy is to overcome the dichotomy of the immune response: tumor-evoked immunostimulatory versus tumor-induced immunosuppressive. The goal needs to be two-fold, to re-establish sustainable antitumor-cancer immunity and to eliminate immunosuppression. The successful elimination of cancer cells by immunosurveillance requires the antigenic presentation of the tumor cells or tumor-associated antigens and the expression of immunostimulatory cytokines and chemokines by cancer and immune cells. Tumors are heterogeneous and as such, some of the tumor cells are thought to have stem cell characteristics that enable them to suppress or desensitize the host immunity due to acquired epigenetic changes. A central mechanism underlying tumor epigenetic instability is the increased histone deacetylase (HDAC)-mediated repression of HDAC-target genes regulating homeostasis and differentiation. It was noted that pharmacological HDAC inhibitors are not effective in eliminating tumor cells partly because they may induce immunosuppression. We have shown that epithelial-specific tumor suppressor maspin, an ovalbumin-like non-inhibitory serine protease inhibitor, reprograms tumor cells toward better differentiated phenotypes by inhibiting HDAC1. Recently, we uncovered a novel function of maspin in directing host immunity towards tumor elimination. In this review, we discuss the maspin and maspin/HDAC1 interplay in tumor biology and immunology. We propose that maspin based therapies may eradicate cancer.

Maspin expression in prostate tumor elicits host anti-tumor immunity

The goal of the current study is to examine the biological effects of epithelial-specific tumor suppressor maspin on tumor host immune response. Accumulated evidence demonstrates an anti-tumor effect of maspin on tumor growth, invasion and metastasis. The molecular mechanism underlying these biological functions of maspin is thought to be through histone deacetylase inhibition, key to the maintenance of differentiated epithelial phenotype. Since tumor-driven stromal reactivities co-evolve in tumor progression and metastasis, it is not surprising that maspin expression in tumor cells inhibits extracellular matrix degradation, increases fibrosis and blocks hypoxia-induced angiogenesis. Using the athymic nude mouse model capable of supporting the growth and progression of xenogeneic human prostate cancer cells, we further demonstrate that maspin expression in tumor cells elicits neutrophil- and B cells-dependent host tumor immunogenicity. Specifically, mice bearing maspin-expressing tumors exhibited increased systemic and intratumoral neutrophil maturation, activation and antibody-dependent cytotoxicity, and decreased peritumoral lymphangiogenesis. These results reveal a novel biological function of maspin in directing host immunity towards tumor elimination that helps explain the significant reduction of xenograft tumor incidence in vivo and the clinical correlation of maspin with better prognosis of several types of cancer. Taken together, our data raised the possibility for novel maspin-based cancer immunotherapies.

HDAC inhibitors and immunotherapy; a double edged sword?

Epigenetic modifications, like histone acetylation, are essential for regulating gene expression within cells. Cancer cells acquire pathological epigenetic modifications resulting in gene expression patterns that facilitate and sustain tumorigenesis. Epigenetic manipulation therefore is emerging as a novel targeted therapy for cancer. Histone Acetylases (HATs) and Histone Deacetylases (HDACs) regulate histone acetylation and hence gene expression. Histone deacetylase (HDAC) inhibitors are well known to affect cancer cell viability and biology and are already in use for the treatment of cancer patients. Immunotherapy can lead to clinical benefit in selected cancer patients, especially in patients with limited disease after tumor debulking. HDAC inhibitors can potentially synergize with immunotherapy by elimination of tumor cells. The direct effects of HDAC inhibitors on immune cell function, however, remain largely unexplored. Initial data have suggested HDAC inhibitors to be predominantly immunosuppressive, but more recent reports have challenged this view. In this review we will discuss the effects of HDAC inhibitors on tumor cells and different immune cell subsets, synergistic interactions and possible mechanisms. Finally, we will address future challenges and potential application of HDAC inhibitors in immunocombination therapy of cancer.

Histone deacetylases inhibitor Trichostatin A ameliorates DNFB-induced allergic contact dermatitis and reduces epidermal Langerhans cells in mice

BACKGROUND

Histone deacetylases (HDACs) influence chromatin organization, representing a key epigenetic regulatory mechanism in cells. Trichostatin A (TSA), a potent HDAC inhibitor, has anti-tumor and anti-inflammatory effects. Allergic contact dermatitis (ACD) is a T-cell-mediated inflammatory reaction in skin and is regulated by epidermal Langerhans cells (LCs).

OBJECTIVE

The aim of this study was to investigate if TSA treatment prevents 2,4-dinitrofluorobenzene (DNFB)-induced ACD in mice and regulates epidermal LCs and other immune cells during ACD development.

METHODS

ACD was induced by sensitizing and challenging with DNFB topically. Mice were treated intraperitoneally with TSA or vehicle DMSO as a control every other day before and during induction of ACD. The ear swelling response was measured and skin biopsies from sensitized skin areas were obtained for histology. Epidermal cells, thymus, spleen and skin draining lymph nodes were collected for immune staining.

RESULTS

TSA treatment ameliorated skin lesion severity of DNFB-induced ACD. The percentages of epidermal LCs and splenic DCs as well as LC maturation were significantly reduced in TSA-treated mice. However, TSA treatment did not significantly affect the homeostasis of conventional CD4(+) and CD8(+) T cells, Foxp3(+)CD4(+) regulatory T cells, iNKT cells, and γδ T cells in thymus, spleen and draining lymph nodes (dLNs). Furthermore, there were no significant differences in IL-4 and IFN-γ-producing T cells and iNKT cells between TSA- and DMSO-treated mice.

CONCLUSION

Our findings suggest that TSA may ameliorate ACD through the regulation of epidermal LCs and HDACs could serve as potential therapeutic targets for ACD and other LCs-related skin diseases.

Immunotherapy augments the effect of 5-azacytidine on HPV16-associated tumours with different MHC class I-expression status

BACKGROUND

Epigenetic mechanisms have important roles in the tumour escape from immune responses, such as in MHC class I downregulation or altered expression of other components involved in antigen presentation. Chemotherapy with DNA methyltransferase inhibitors (DNMTi) can thus influence the tumour cell interactions with the immune system and their sensitivity to immunotherapy.

METHODS

We evaluated the therapeutic effects of the DNMTi 5-azacytidine (5AC) against experimental MHC class I-deficient and -positive tumours. The 5AC therapy was combined with immunotherapy, using a murine model for HPV16-associated tumours.

RESULTS

We have demonstrated 5AC additive effects against MHC class I-positive and -deficient tumours when combined with unmethylated CpG oligodeoxynucleotides or with IL-12-producing cellular vaccine. The efficacy of the combined chemoimmunotherapy against originally MHC class I-deficient tumours was partially dependent on the CD8(+)-mediated immune responses. Increased cell surface expression of MHC class I cell molecules, associated with upregulation of the antigen-presenting machinery-related genes, as well as of genes encoding selected components of the IFNγ-signalling pathway in tumours explanted from 5AC-treated animals, were observed.

CONCLUSION

Our data suggest that chemotherapy of MHC class I-deficient tumours with 5AC combined with immunotherapy is an attractive setting in the treatment of MHC class I-deficient tumours.