Epigenetic Modification in Macrophages: A Promising Target for Tumor and Inflammation-associated Disease Therapy

Macrophage polarization regulation shed lights on immunotherapy for CaOx kidney stone disease

Kidney stone disease (KSD) is a major public health concern associated with high morbidity and recurrence, places a significant burden on the health care system worldwide. Calcium oxalate (CaOx) alone or a mixture of CaOx and calcium phosphate stones accounting for more than 80 % of cases. However, beyond surgical removal, the prevention and reduction of recurrence of CaOx kidney stones have always been a challenge. Given that macrophages are traditional innate immune cells that play critical roles in the clearance of pathogens and the maintenance of tissue homeostasis, which have gained more and more interests in nephrolithiasis. Several studies recently clearly demonstrated that M2-macrophage could reduce the renal calcium oxalate (CaOx) crystal acumination, and provide premise insights and therapeutic options for KSD by modulating the macrophage phenotypes. However, the mechanism of macrophage-polarization regulation and that effects on kidney stone prevention and treatments are far from clear. Here, we comprehensively reviewed the literatures related to cytokines, epigenetic modifications and metabolic reprograming of macrophage in CaOx kidney stone disease, aimed to provide better understandings on macrophage polarization regulation as well as its potential clinical applications in CaOx kidney stone disease treatments and prevention.

LSD1 in drug discovery: From biological function to clinical application

Lysine-specific demethylase 1 (LSD1) is a flavin adenine dinucleotide (FAD) dependent monoamine oxidase (MAO) that erases the mono-, and dimethylation of histone 3 lysine 4 (H3K4), resulting in the suppression of target gene transcriptions. Besides, it can also demethylate some nonhistone substrates to regulate their biological functions. As reported, LSD1 is widely upregulated and plays a key role in several kinds of cancers, pharmacological or genetic ablation of LSD1 in cancer cells suppresses cell aggressiveness by several distinct mechanisms. Therefore, numerous LSD1 inhibitors, including covalent and noncovalent, have been developed and several of them have entered clinical trials. Herein, we systemically reviewed and discussed the biological function of LSD1 in tumors, lymphocytes as well as LSD1-targeting inhibitors in clinical trials, hoping to benefit the field of LSD1 and its inhibitors.

The HDAC2-SP1 Axis Orchestrates Protumor Macrophage Polarization

Tumor-associated macrophages (TAM), including antitumor M1-like TAMs and protumor M2-like TAMs, are transcriptionally dynamic innate immune cells with diverse roles in lung cancer development. Epigenetic regulators are key in controlling macrophage fate in the heterogeneous tumor microenvironment. Here, we demonstrate that the spatial proximity of HDAC2-overexpressing M2-like TAMs to tumor cells significantly correlates with poor overall survival of lung cancer patients. Suppression of HDAC2 in TAMs altered macrophage phenotype, migration, and signaling pathways related to interleukins, chemokines, cytokines, and T-cell activation. In coculture systems of TAMs and cancer cells, suppressing HDAC2 in TAMs resulted in reduced proliferation and migration, increased apoptosis of cancer cell lines and primary lung cancer cells, and attenuated endothelial cell tube formation. HDAC2 regulated the M2-like TAM phenotype via acetylation of histone H3 and transcription factor SP1. Myeloid cell-specific deletion of Hdac2 and pharmacologic inhibition of class I HDACs in four different murine lung cancer models induced the switch from M2-like to M1-like TAMs, altered infiltration of CD4+ and CD8+ T cells, and reduced tumor growth and angiogenesis. TAM-specific HDAC2 expression may provide a biomarker for lung cancer stratification and a target for developing improved therapeutic approaches.

SIGNIFICANCE

HDAC2 inhibition reverses the protumor phenotype of macrophages mediated by epigenetic modulation induced by the HDAC2-SP1 axis, indicating a therapeutic option to modify the immunosuppressive tumor microenvironment.

Targeting LSD1 in tumor immunotherapy: rationale, challenges and potential

Lysine-specific demethylase 1 (LSD1) is an enzyme that removes lysine methylation marks from nucleosome histone tails and plays an important role in cancer initiation, progression, metastasis, and recurrence. Recent research shows that LSD1 regulates tumor cells and immune cells through multiple upstream and downstream pathways, enabling tumor cells to adapt to the tumor microenvironment (TME). As a potential anti-tumor treatment strategy, immunotherapy has developed rapidly in the past few years. However, most patients have a low response rate to available immune checkpoint inhibitors (ICIs), including anti-PD-(L)1 therapy and CAR-T cell therapy, due to a broad array of immunosuppressive mechanisms. Notably, inhibition of LSD1 turns "cold tumors" into "hot tumors" and subsequently enhances tumor cell sensitivity to ICIs. This review focuses on recent advances in LSD1 and tumor immunity and discusses a potential therapeutic strategy for combining LSD1 inhibition with immunotherapy.

Discovery of acridine-based LSD1 inhibitors as immune activators targeting LSD1 in gastric cancer

LSD1 is overexpressed in various cancers and promotes tumor cell proliferation, tumor expansion, and suppresses immune cells infiltration and is closely associated with immune checkpoint inhibitors therapy. Therefore, the inhibition of LSD1 has been recognized as a promising strategy for cancer therapy. In this study, we screened an in-house small-molecule library targeting LSD1, an FDA-approved drug amsacrine for acute leukemia and malignant lymphomas was found to exhibit moderate anti-LSD1 inhibitory activity (IC₅₀ = 0.88 μM). Through further medicinal chemistry efforts, the most active compound 6x increased anti-LSD1 activity significantly (IC₅₀ = 0.073 μM). Further mechanistic studies demonstrated that compound 6x inhibited the stemness and migration of gastric cancer cell, and decreased the expression of PD-L1 (programmed cell death-ligand 1) in BGC-823 and MFC cells. More importantly, BGC-823 cells are more susceptible to T-cell killing when treated with compound 6x. Moreover, tumor growth was also suppressed by compound 6x in mice. Altogether, our findings demonstrated that acridine-based novel LSD1 inhibitor 6x may be a lead compound for the development of activating T cell immune response in gastric cancer cells.

GABA regulates IL-1β production in macrophages

Neurotransmitters have been well documented to determine immune cell fates; however, whether and how γ-amino butyric acid (GABA) shapes the function of innate immune cells is still obscure. Here, we demonstrate that GABA orchestrates macrophage maturation and inflammation. GABA treatment during macrophage maturation inhibits interleukin (IL)-1β production from inflammatory macrophages. Mechanistically, GABA enhances succinate-flavin adenine dinucleotide (FAD)-lysine specific demethylase1 (LSD1) signaling to regulate histone demethylation of Bcl2l11 and Dusp2, reducing formation of the NLRP3-ASC-Caspase-1 complex. The GABA-succinate axis reduces succinylation of mitochondrial proteins to promote oxidative phosphorylation (OXPHOS). We also find that GABA alleviates lipopolysaccharides (LPS)-induced sepsis as well as high-fat-diet-induced obesity in mice. Our study shows that GABA regulates pro-inflammatory macrophage responses associated with metabolic reprogramming and protein succinylation, suggesting a strategy for treating macrophage-related inflammatory diseases.

Biological and therapeutic role of LSD1 in Alzheimer’s diseases

Alzheimer’s disease (AD) is a common chronic neurodegenerative disease characterized by cognitive learning and memory impairments, however, current treatments only provide symptomatic relief. Lysine-specific demethylase 1 (LSD1), regulating the homeostasis of histone methylation, plays an important role in the pathogenesis of many neurodegenerative disorders. LSD1 functions in regulating gene expression via transcriptional repression or activation, and is involved in initiation and progression of AD. Pharmacological inhibition of LSD1 has shown promising therapeutic benefits for AD treatment. In this review, we attempt to elaborate on the role of LSD1 in some aspects of AD including neuroinflammation, autophagy, neurotransmitters, ferroptosis, tau protein, as well as LSD1 inhibitors under clinical assessments for AD treatment.

Protective Effect of Galangin Methylation Modification Based on Cell Imaging on Inflammatory Lung Injury and Its Molecular Mechanism

Background

Recently, inflammation has become a major threat to human health. Studies have confirmed that some Chinese traditional medicine ingredients may effectively interfere with the expression of inflammatory mediators through epigenetic modification, showing a great potential of the application.

Objective

To investigate the role of the PPAR/DNMT3A pathway in the reversal of galangin-mediated inflammatory lung injury, promote the development of new anti-inflammatory drugs, reduce the side effects of chemical synthetic drugs on the body, and prove the effectiveness and safety of galangin in inhibiting inflammatory response and injury.

Methods

120 rats were randomly divided into 6 groups: (Group 1) LPS group; (Group 2) LPS + galangin group; (Group 3) LPS + galangin +  GW9662 group; (Group 4) LPS + galangin + DNMT3A siRNA group; (Group 5) LPS + galangin + siRNA negative group; (Group 6) control group. The model of inflammatory lung injury was established by intrathecal instillation of LPS in the first five groups and NS in the control group. SD survival rate was recorded every 24 hours after modeling, lasting for 168 hours. The lung tissues were taken 168 hours after the establishment of the model. The pathological morphology of lung tissue was observed after the staining under the light microscope, and the lung dry/wet weight ratio was calculated after drying. After NS was perfused into lung tissue, the lavage fluid was collected and the levels of IL-6 and TNF-a were measured by ELISA. The contents of PPAR, DNMT3A, phosphorylated p65, and ERK in monocytes were detected by the WB method, and the binding contents of p65 and AP-1 in the promoter regions of IL-6 and TNF-a genes were detected by the Chip-qPCR method.

Results

Intraperitoneal injection of galangin could inhibit the synthesis of alveolar inflammatory factors (TFs) in the SD model of lung injury induced by LPS, reduce the degree of pathological injury of lung tissue, and improve the survival rate of the SD model. GW9662 can completely reverse the protective effect, while DNMT3A interference can only partially block its protective effect. In addition, galangin could significantly inhibit the LPS-induced expression of p65 and AP-1 in alveolar monocytes and their binding content in the promoter region of inflammatory genes by activating PPAR/DNMT3A pathway. GW9662 could completely reverse the inhibitory effect of galangin. DNMT3A interference could restore the binding content of transcription factors at the promoter of the inflammatory gene but had no significant effect on its synthesis.

Conclusion

Galangin can interfere with the binding of transcription factors to inflammatory gene promoters through the methylation modification induced by PPAR/DNMT3A pathway, so as to inhibit the synthesis of inflammatory molecules and reverse inflammatory lung injury.

Novel pharmacological inhibition of JMJD3 improves necrotizing enterocolitis by attenuating the inflammatory response and ameliorating intestinal injury

Necrotizing enterocolitis (NEC), an acute intestinal inflammatory disease of premature infants, is one of the leading causes of death in neonates. Effective measures for clinical treatment are limited and there is a pressing need in searching for new therapeutic strategies. Jumonji domain-containing protein D3 (JMJD3), a histone H3 lysine 27 (H3K27) demethylase plays a proinflammatory role in sepsis and neuroinflammation. However, whether JMJD3 is involved in the pathogenesis of NEC has not been elucidated. Here we report that overexpressed JMJD3 was revealed in the intestine of NEC patients by bioinformatic analysis. Moreover, upregulated JMJD3 and suppressed H3K27me3 were detected in both NEC patients and neonatal mice subjected to experimental NEC. Importantly, administration of GSK-J4, a specific JMJD3 inhibitor, rescued neonatal mice from NEC-associated lethality by suppressing proinflammatory response with attenuated IL-6, TNF-α, and MCP-1 levels and ameliorating intestinal injury with reversed claudin-1, occludin, and E-cadherin expression. Remarkably, administration of GSK-J4 attenuated intestinal injury by inhibiting activation of intestinal necroptosis in NEC mice. Administration of GSK-J4 regulated intestinal inflammation via NF-κB and JAK2/STAT3 pathway. These results indicate that JMJD3 is involved in the development of NEC and inhibition of JMJD3 overexpression by mean of GSK-J4 could be a potential therapeutic approach in the prevention and treatment of NEC.

Recent Developments of Coumarin-based Hybrids in Drug Discovery

Coumarin scaffold is a highly significant O-heterocycle, namely benzopyran-2-ones, form an elite class of naturally occurring compounds that possess promising therapeutic perspectives. Based on its broad spectrum of biological activities, the privileged coumarin scaffold is applied to medicinal and pharmacological treatments by several rational design strategies and approaches. Structure-activity relationships of the coumarin-based hybrids with various bioactivity fragments revealed significant information toward the further development of highly potent and selective disorder therapeutic agents. The molecular docking studies between coumarins and critical therapeutic enzymes demonstrated mode of action by forming noncovalent interactions with more than one receptor, further rationally confirm information about structure-activity relationships. This review summarizes recent developments relating to coumarin-based hybrids with other pharmacophores aiming to numerous feasible therapeutic enzymatic targets to combat various therapeutic fields, including anticancer, antimicrobic, anti-Alzheimer, anti-inflammatory activities.

Histone Methylation Related Therapeutic Challenge in Cardiovascular Diseases

The epidemic of cardiovascular diseases (CVDs) is predicted to spread rapidly in advanced countries accompanied by the high prevalence of risk factors. In terms of pathogenesis, the pathophysiology of CVDs is featured by multiple disorders, including vascular inflammation accompanied by simultaneously perturbed pathways, such as cell death and acute/chronic inflammatory reactions. Epigenetic alteration is involved in the regulation of genome stabilization and cellular homeostasis. The association between CVD progression and histone modifications is widely known. Among the histone modifications, histone methylation is a reversible process involved in the development and homeostasis of the cardiovascular system. Abnormal methylation can promote CVD progression. This review discusses histone methylation and the enzymes involved in the cardiovascular system and determine the effects of histone methyltransferases and demethylases on the pathogenesis of CVDs. We will further demonstrate key proteins mediated by histone methylation in blood vessels and review histone methylation-mediated cardiomyocytes and cellular functions and pathways in CVDs. Finally, we will summarize the role of inhibitors of histone methylation and demethylation in CVDs and analyze their therapeutic potential, based on previous studies.

Biotin-streptavidin-guided two-step pretargeting approach using PLGA for molecular ultrasound imaging and chemotherapy for ovarian cancer

Background

Ovarian cancer seriously threatens the lives and health of women, and early diagnosis and treatment are still challenging. Pre-targeting is a promising strategy to improve the treatment efficacy of ovarian cancer and the results of ultrasound imaging.

Purpose

To explore the effects of a pre-targeting strategy using streptavidin (SA) and paclitaxel (PTX)-loaded phase-shifting poly lactic-co-glycolic acid (PLGA) nanoparticles with perfluoro-n-pentane (PTX-PLGA-SA/PFPs) on the treatment and ultrasound imaging of ovarian cancer.

Methods

PTX-PLGA/PFPs were prepared with a single emulsion (O/W) solvent evaporation method and SA was attached using carbodiimide. The encapsulation efficiency of PTX and the release characteristics were assessed with high performance liquid chromatography. The phase-change characteristics of the PTX-PLGA-SA/PFPs were investigated. The anti-carcinoembryonic antigen (CEA) antibody (Ab) was covalently attached to PTX-PLGA/PFPs via carbodiimide to create PTX-PLGA-Ab/PFPs. The targeting efficiency of the nanoparticles and the viability of ovarian cancer SKOV3 cells were evaluated in each group using a microscope, flow cytometry, and cell counting kit 8 assays.

Results

THE PTX-PLGA-SA/PFPs were spheres with a size of 383.0 ± 75.59 nm. The encapsulation efficiency and loading capability of the nanoparticles for PTX were 71.56 ±  6.51% and 6.57 ± 0.61%, respectively. PTX was burst-released up to 70% in 2–3 d. When irradiated at 7.5 W for 3 min, the PTX-PLGA-SA/PFPs visibly enhanced the ultrasonography images (P < 0.05). At temperatures of 45°C and 60°C the nanoparticles phase-shifted into micro-bubbles and the sizes increased. The binding efficiencies of SA and Ab to the PTX-PLGA/PFPs were 97.16 ±  1.20% and 92.74 ± 5.75%, respectively. Pre-targeting resulted in a high binding efficacy and killing effect on SKOV3 cells (P < 0.05).

Conclusions

The two-step pre-targeting process can significantly enhance the targeting ability of PTX-loaded PLGA nanoparticles for ovarian cancer cells and substantially improve the therapeutic efficacy. This technique provides a new method for ultrasonic imaging and precise chemotherapy for ovarian cancer.

Lysine-specific demethylase 1 (LSD1) serves as an potential epigenetic determinant to regulate inflammatory responses in mastitis

It is well-established that lysine-specific demethylase 1 (LSD1) is the first identified histone demethylase. Based on its demethylase enzymatic activity, LSD1 plays a pivotal role in vast range of cellular processes and cancers, but the understanding of its effects on inflammation is relatively limited. Using in vivo models of lipopolysaccharide (LPS)-induced inflammation and in vitro assays in mouse mammary epithelial cells, we identified the novel regulatory roles and underlying mechanisms of LSD1 on LPS-induced mastitis. Mammary gland and cells were collected for the following experiments after treatment. Histological changes were determined by H&E. Western blot analysis was used to detect the protein expression. ELISA and real-time PCR were used to evaluate protein and mRNA expression of inflammatory genes. Our results showed that LPS treatment resulted in a significant increase in LSD1 protein expression. GSK-LSD1 is a selective inhibitor of LSD1 enzyme activity. Treatment of mice with GSK-LSD1 inhibited LSD1 activity, reduced inflammatory cells recruitment to tissues and attenuated LPS-induced damage in mammary gland. Mechanistic investigations suggested that LSD1 inhibition led to the increase of histone H3K4me2 and H3K9me2. Furthermore, GSK-LSD1 inhibition of LSD1 further inhibited nuclear factor κ-B (NF-κB) signaling cascades, and subsequently inhibited the production of cytokines (TNF-α, IL-6 and IL-1β) in mammary gland. Taken together, our data reveal LSD1 as a potential regulator of inflammation and improve our understanding of epigenetic control on inflammation.

SUV39H1-Mediated DNMT1 is Involved in the Epigenetic Regulation of Smad3 in Cervical Cancer

BACKGROUND

SMAD3 is a pivotal intracellular mediator for participating in the activation of multiple immune signal pathways.

OBJECTIVE

The epigenetic regulation mechanism of the positive immune factor SMAD3 in cervical cancer remains unknown. Therefore, the epigenetic regulation on SMAD3 is investigated in this study.

METHODS

The methylation status of SMAD3 was detected by Methylation-Specific PCR (MS-PCR) and Quantitative Methylation-Specific PCR (MS-qPCR) in cervical cancer tissues and cell lines. The underlying molecular mechanisms of SUV39H1-DNMT1-SMAD3 regulation were elucidated using cervical cancer cell lines containing siRNA or/and over-expression systems. The regulation of DNMT1 by SUV39H1 was confirmed using Chromatin Immunoprecipitation-qPCR (ChIP-qPCR). The statistical methods used for comparing samples between groups were paired t-tests and one-way ANOVAs.

RESULTS

H3K9me3 protein regulated by SUV39H1 directly interacts with the DNMT1 promoter region to regulate its expression in cervical cancer cells, resulting in the reduced expression of the downstream target gene DNMT1. In addition, DNMT1 mediates the epigenetic modulation of the SMAD3 gene by directly binding to its promoter region. The depletion of DNMT1 effectively restores the expression of SMAD3 in vitro. Moreover, in an in vivo assay, the expression profile of SUV39H1-DNMT1 was found to correlate with SMAD3 expression in accordance with the expression at the cellular level. Notably, the promoter region of SMAD3 was hypermethylated in cervical cancer tissues, and this hypermethylation inhibited the subsequent gene expression.

CONCLUSION

These results indicate that SUV39H1-DNMT1 is a crucial SMAD3 regulatory axis in cervical cancer. SUV39H1-DNMT1 axis may provide a potential therapeutic target for the treatment of cervical cancer.

PGN and LTA from Staphylococcus aureus Induced Inflammation and Decreased Lactation through Regulating DNA Methylation and Histone H3 Acetylation in Bovine Mammary Epithelial Cells

Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) are the most common pathogens of mastitis, and S. aureus generally causes subclinical mastitis which is more persistent and resistant to treatment. Peptidoglycan (PGN) and lipoteichoic acid (LTA) are cell wall components of S. aureus. Although the roles of PGN and LTA in causing inflammation are well studied, the epigenetic mechanisms of the effects of PGN and LTA on the inflammation and lactation remain poorly understood. This study characterized the gene expression profiling by RNA sequencing and investigated DNA methylation and histone acetylation in relation to inflammation and lactation in the immortalized bovine mammary epithelial cell line (MAC-T). The cells were cultured for 24 h with neither PGN nor LTA (CON), PGN (30 μg/mL), LTA (30 μg/mL), and PGN (30 μg/mL) + LTA (30 μg/mL), respectively. The number of differentially expressed genes (DEGs) and the expression of proinflammatory factors including interleukin (IL)-1β, IL-6, IL-8, chemokine (C-X-C motif) ligand (CXCL)1, and CXCL6 of the treatments increased in the following order: CON < PGN < LTA < PGN + LTA, and the DEGs mainly enriched on the cytokine-cytokine receptor interaction and chemokine signaling pathway. LTA and PGN + LTA induced hypomethylation of global DNA by suppressing DNA methyltransferase (DNMT) activity. PGN and LTA, alone or combined, decreased the mRNA expression of casein genes (CSN1S1, CSN2, and CSN3) and the expression of two caseins (CSN2 and CSN3), and reduced histone H3 acetylation by suppressing histone acetyltransferase (HAT) activity and promoting histone deacetylase (HDAC) activity. Collectively, this study revealed that PGN and LTA induced inflammation probably due to decreasing DNA methylation through regulating DNMT activity, and decreased lactation possibly through reducing histone H3 acetylation by regulating HAT and HDAC activity in bovine mammary epithelial cells.

The Impact of Type 1 Interferons on Alveolar Macrophage Tolerance and Implications for Host Susceptibility to Secondary Bacterial Pneumonia

That macrophages adapt to environmental cues is well-established. This adaptation has had several reiterations, first with innate imprinting and then with various combinations of trained, tolerant, paralyzed, or primed. Whatever the nomenclature, it represents a macrophage that is required to perform very different functions. First, alveolar macrophages are one of the sentinel cells that flag up damage and release mediators that attract other immune cells. Next, they mature to support T cell priming and survival. Finally they are critical in clearing inflammatory immune cells by phagocytosis and extracellular matrix turnover components by efferocytosis. At each functional stage they alter intrinsic components to guide their activity. Training therefore is akin to changing function. In this mini-review we focus on the lung and the specific role of type I interferons in altering macrophage activity. The proposed mechanisms of type I IFNs on lung-resident alveolar macrophages and their effect on host susceptibility to bacterial infection following influenza virus infection.