The histone demethylase LSD1 promotes renal inflammation by mediating TLR4 signaling in hepatitis B virus-associated glomerulonephritis

HBx promotes glomerular podocyte-induced immune cell responses

BACKGROUND

Podocytes, as intrinsic renal cells, can also express MHC-II and costimulatory molecules under inflammatory conditions, suggesting that they may act as antigen-presenting cells (APCs) to activate immune cell responses and then lead to immune-mediated renal injury. They are already recognized as main targets in the pathogenic mechanism of hepatitis B virus (HBV)-associated glomerulonephritis (HBV-GN). Previous studies also have indicated that inflammatory cells infiltration and immune-mediated tissue injury are evident in the kidney samples of patients with HBV-GN. However, the role of podocytes immune disorder in the pathogenic mechanism of HBV-GN remains unclear.

METHODS

Renal function and inflammatory cells infiltration were measured in HBV transgenic (HBV-Tg) mice. In vitro, podocytes/CD4+ T cells or macrophages co-culture system was established. Then, the expression of HBx, CD4, and CD68 was determined by immunohistochemistry, while the expression of MHC-II, CD40, and CD40L was determined by immunofluorescence. Co-stimulatory molecules expression was examined by flow cytometry. The levels of inflammatory factors were detected by ELISA.

RESULTS

In vivo, renal function was obviously impaired in HBV-Tg mice. HBx was significantly upregulated and immune cells infiltrated in the glomerulus of HBV-Tg mice. Expression of MHC-II and costimulatory molecule CD40 increased in the podocytes of HBV-Tg mice; CD4+ T cells exhibited increased CD40L expression in glomerulus. In vitro, CD40 expression was markedly elevated in HBx-podocytes. In co-culture systems, HBx-podocytes stimulated CD4+ T cells activation and caused the imbalance between IFN-γ and IL-4. HBx-podocytes also enhanced the adhesion ability of macrophages and induced the release of proinflammatory mediators.

CONCLUSION

Taken together, these podocyte-related immune disorder may be involved in the pathogenic mechanism of HBV-GN.

miR-708-3p targetedly regulates LSD1 to promote osteoblast differentiation of hPDLSCs in periodontitis

Periodontitis (PD) is a multifactorial inflammatory disease associated with periodontopathic bacteria. Lysine-specific demethylase 1 (LSD1), a type of histone demethylase, has been implicated in the modulation of the inflammatory response process in oral diseases by binding to miRNA targets. This study investigates the molecular mechanisms by which miRNA binds to LSD1 and its subsequent effect on osteogenic differentiation. First, human periodontal ligament stem cells (hPDLSCs) were isolated, cultured, and characterized. These cells were then subjected to lipopolysaccharide (LPS) treatment to induce inflammation, after which osteogenic differentiation was initiated. qPCR and western blot were employed to monitor changes in LSD1 expression. Subsequently, LSD1 was silenced in hPDLSCs to evaluate its impact on osteogenic differentiation. Through bioinformatics and dual luciferase reporter assay, miR-708-3p was predicted and confirmed as a target miRNA of LSD1. Subsequently, miR-708-3p expression was assessed, and its role in hPDLSCs in PD was evaluated through overexpression. Using chromatin immunoprecipitation (ChIP) and western blot assay, we explored the potential regulation of osterix (OSX) transcription by miR-708-3p and LSD1 via di-methylated H3K4 (H3K4me2). Finally, we investigated the role of OSX in hPDLSCs. Following LPS treatment of hPDLSCs, the expression of LSD1 increased, but this trend was reversed upon the induction of osteogenic differentiation. Silencing LSD1 strengthened the osteogenic differentiation of hPDLSCs. miR-708-3p was found to directly bind to and negatively regulate LSD1, leading to the repression of OSX transcription through demethylation of H3K4me2. Moreover, overexpression of miR-708-3p was found to promote hPDLSCs osteogenic differentiation in inflammatory microenvironment. However, the protective effect was partially attenuated by reduced expression of OSX. Our findings indicate that miR-708-3p targetedly regulates LSD1 to enhance OSX transcription via H3K4me2 methylation, ultimately promoting hPDLSCs osteogenic differentiation.

Role of Histone Modifications in Kidney Fibrosis

Chronic kidney disease (CKD) is characterized by persistent kidney dysfunction, ultimately resulting in end-stage renal disease (ESRD). Renal fibrosis is a crucial pathological feature of CKD and ESRD. However, there is no effective treatment for this condition. Despite the complex molecular mechanisms involved in renal fibrosis, increasing evidence highlights the crucial role of histone modification in its regulation. The reversibility of histone modifications offers promising avenues for therapeutic strategies to block or reverse renal fibrosis. Therefore, a comprehensive understanding of the regulatory implications of histone modifications in fibrosis may provide novel insights into more effective and safer therapeutic approaches. This review highlights the regulatory mechanisms and recent advances in histone modifications in renal fibrosis, particularly histone methylation and histone acetylation. The aim is to explore the potential of histone modifications as targets for treating renal fibrosis.

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.

Influences of lysine-specific demethylase 1 inhibitors on NO synthase-Kruppel-like factor pathways in human endothelial cells in vitro and zebrafish (Danio rerio) larvae in vivo

Lysine-specific demethylase 1 (LSD1) inhibitors are being developed for cancer therapy, but their bioeffects on vasculatures are not clear. In this study, we compared the influences of ORY-1001 (an LSD1 inhibitor being advanced into clinical trials) and 199 (a novel LSD1 inhibitor recently developed by us) to human umbilical vein endothelial cells (HUVECs) in vitro and further verified the bioeffects of ORY-1001 to zebrafish (Danio rerio) larvae in vivo. The results showed that up to 10 μM ORY-1001 or 199 did not significantly affect the cellular viability of HUVECs but substantially reduced the release of inflammatory interleukin-8 (IL-8) and IL-6. The signaling molecule in vasculatures, NO, was also increased in HUVECs. As the mechanism, the protein levels of endothelial NO synthase (eNOS) or p-eNOS, and their regulators Kruppel-like factor 2 (KLF2) or KLF4, were also increased after drug treatment. In vivo, 24 h treatment with up to 100 nM ORY-1001 reduced blood speed without changing morphologies or locomotor activities in zebrafish larvae. ORY-1001 treatment reduced the expression of il8 but promoted the expression of klf2a and nos in the zebrafish model. These data show that LSD1 inhibitors were not toxic but capable to inhibit inflammatory responses and affect the function of blood vessels through the up-regulation of the NOS-KLF pathway.

Lysine-Specific Demethylase 1 (LSD1) Inhibitors: Peptides as an Emerging Class of Therapeutics

Aberrant expression of the epigenetic regulator lysine-specific demethylase 1 (LSD1) has been associated with the incidence of many diseases, particularly cancer, and it has evolved as a promising epigenetic target over the years for treatment. The advent of LSD1 inhibitor-based clinical utility began with tranylcypromine, and it is now considered an inevitable scaffold in the search for other irreversible novel LSD1 inhibitors (IMG-7289 or bomedemstat, ORY1001 or iadademstat, ORY-2001 or vafidemstat, GSK2879552, and INCB059872). Moreover, numerous reversible inhibitors for LSD1 have been reported in the literature, including clinical candidates CC-90011 (pulrodemstat) and SP-2577 (seclidemstat). There is parallel mining for peptide-based LSD1 inhibitors, which exploits the opportunities in the LSD1 substrate binding pocket. This Review highlights the research progress on reversible and irreversible peptide/peptide-derived LSD1 inhibitors. For the first time, we comprehensively organized the peptide-based LSD1 inhibitors from the design strategy. Peptide inhibitors of LSD1 are classified as H3 peptide and SNAIL1 peptide derivatives, along with miscellaneous peptides that include naturally occurring LSD1 inhibitors.

Demethylase-independent roles of LSD1 in regulating enhancers and cell fate transition

The major enhancer regulator lysine-specific histone demethylase 1A (LSD1) is required for mammalian embryogenesis and is implicated in human congenital diseases and multiple types of cancer; however, the underlying mechanisms remain enigmatic. Here, we dissect the role of LSD1 and its demethylase activity in gene regulation and cell fate transition. Surprisingly, the catalytic inactivation of LSD1 has a mild impact on gene expression and cellular differentiation whereas the loss of LSD1 protein de-represses enhancers globally and impairs cell fate transition. LSD1 deletion increases H3K27ac levels and P300 occupancy at LSD1-targeted enhancers. The gain of H3K27ac catalyzed by P300/CBP, not the loss of CoREST complex components from chromatin, contributes to the transcription de-repression of LSD1 targets and differentiation defects caused by LSD1 loss. Together, our study demonstrates a demethylase-independent role of LSD1 in regulating enhancers and cell fate transition, providing insight into treating diseases driven by LSD1 mutations and misregulation.

Histone demethylases in the regulation of immunity and inflammation

Pathogens or danger signals trigger the immune response. Moderate immune response activation removes pathogens and avoids excessive inflammation and tissue damage. Histone demethylases (KDMs) regulate gene expression and play essential roles in numerous physiological processes by removing methyl groups from lysine residues on target proteins. Abnormal expression of KDMs is closely associated with the pathogenesis of various inflammatory diseases such as liver fibrosis, lung injury, and autoimmune diseases. Despite becoming exciting targets for diagnosing and treating these diseases, the role of these enzymes in the regulation of immune and inflammatory response is still unclear. Here, we review the underlying mechanisms through which KDMs regulate immune-related pathways and inflammatory responses. In addition, we also discuss the future applications of KDMs inhibitors in immune and inflammatory diseases.

Effect of LSD1 on osteogenic differentiation of human periodontal ligament stem cells in periodontitis

OBJECTIVE

Periodontitis is a chronic inflammation of periodontal tissues. This study is expected to assess the effect of LSD1 on the osteogenic differentiation of hPDLSCs in periodontitis.

METHODS

hPDLSCs were separated, cultivated, and identified, and then treated by LPS to induce inflammatory microenvironment and subjected to osteogenic differentiation. Subsequently, LSD1 expression was determined, and then silenced to assess its effect on hPDLSCs. Next, the binding relation between LSD1 and miR-590-3p was analyzed. miR-590-3p expression was detected and then overexpressed to evaluate its role in hPDLSCs in periodontitis. Afterward, the relation between LSD1 and OSX was analyzed. H3K4me2 level and OSX transcription were measured, and the role of H3K4me2 was determined. Additionally, the role of OSX in hPDLSCs was verified.

RESULTS

LSD1 was poorly expressed after osteogenic differentiation of hPDLSCs while it was rescued upon LPS induction. The osteogenic differentiation of hPDLSC in periodontitis was strengthened upon LSD1 downregulation. Besides, miR-590-3p targeted LSD1 transcription, and LSD1 inhibited OSX transcription via H3K4me2 demethylation. miR-590-3p overexpression improved osteogenic differentiation of hPDLSCs in periodontitis. But this improvement was annulled by OSX inhibition.

CONCLUSION

miR-590-3p targeted LSD1 transcription and upregulated H3K4me2 methylation to promote OSX transcription, thereby encouraging osteogenic differentiation of hPDLSCs in periodontitis.

Bone marrow mesenchymal stem cell-derived exosomes protect podocytes from HBx-induced ferroptosis

Introduction

Hepatitis B virus-associated glomerulonephritis (HBV-GN) is a common secondary kidney disease in China, the pathogenesis of which is not completely clear, and there is still a lack of effective treatment.

Methods

The mechanism of exosomes derived from bone marrow mesenchymal stem cells (BMSCs) was investigated by using HBx-transfected human renal podocytes. Cell viability was detected by CCK8 assay. Iron and malondialdehyde (MDA) contents were detected by using commercial kits. Reactive oxygen species (ROS) levels were measured by flow cytometry analysis. The expression of ferroptosis related molecules was detected by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot. The effect of miR-223-3p transferred by BMSC-derived exosomes on HBx-overexpressing podocytes was proved by using miR-223-3p inhibitor.

Results

The cell viability of podocytes reduced at 72 h or 96 h after the transfection of lentivirus overexpressing HBx protein (p < 0.05). Ferroptosis-related proteins, including glutathione peroxidase 4 (GPX4) and solute carrier family 7 member 11 (SLC7A11) were down-regulated upon HBx overexpression, while acyl-CoA synthetase long-chain family member 4 (ACSL4) was up-regulated (p < 0.05). Intracellular levels of iron, MDA, and ROS were also enhanced (p < 0.05). BMSC-derived exosomes protected against ferroptosis induced by HBx overexpression in podocytes. miR-223-3p was enriched in BMSC-derived exosomes. Application of miR-223-3p inhibitor reversed the protective effect of BMSC-derived exosomes on HBx-induced ferroptosis in podocytes.

Conclusion

BMSC-derived exosomes inhibit HBx-induced podocyte ferroptosis by transferring miR-223-3p.

Pharmacological Inhibition of Lysine-Specific Demethylase 1A Reduces Atherosclerotic Lesion Formation in Apolipoprotein E-Deficient Mice by a Mechanism Involving Decreased Oxidative Stress and Inflammation; Potential Implications in Human Atherosclerosis

Dysregulated epigenetic mechanisms promote transcriptomic and phenotypic alterations in cardiovascular diseases. The role of histone methylation-related pathways in atherosclerosis is largely unknown. We hypothesize that lysine-specific demethylase 1A (LSD1/KDM1A) regulates key molecular effectors and pathways linked to atherosclerotic plaque formation. Human non-atherosclerotic and atherosclerotic tissue specimens, ApoE-/- mice, and in vitro polarized macrophages (Mac) were examined. Male ApoE-/- mice fed a normal/atherogenic diet were randomized to receive GSK2879552, a highly specific LSD1 inhibitor, or its vehicle, for 4 weeks. The mRNA and protein expression levels of LSD1/KDM1A were significantly elevated in atherosclerotic human carotid arteries, atherosclerotic aortas of ApoE-/- mice, and M1-Mac. Treatment of ApoE-/- mice with GSK2879552 significantly reduced the extent of atherosclerotic lesions and the aortic expression of NADPH oxidase subunits (Nox1/2/4, p22phox) and 4-hydroxynonenal-protein adducts. Concomitantly, the markers of immune cell infiltration and vascular inflammation were significantly decreased. LSD1 blockade down-regulated the expression of genes associated with Mac pro-inflammatory phenotype. Nox subunit transcript levels were significantly elevated in HEK293 reporter cells overexpressing LSD1. In experimental atherosclerosis, LSD1 mediates the up-regulation of molecular effectors connected to oxidative stress and inflammation. Together, these data indicate that LSD1-pharmacological interventions are novel targets for supportive therapeutic strategies in atherosclerosis.

DNA methyltransferase 1 knockdown reverses PTEN and VDR by mediating demethylation of promoter and protects against renal injuries in hepatitis B virus-associated glomerulonephritis

Background

Aberrant DNA methylation patterns, including hypermethylation of key genes that inhibit fibrosis and inflammation, have been described in human kidney diseases. However, the role of DNA methyltransferase 1 (DNMT1) in hepatitis B virus-associated glomerulonephritis (HBV-GN) remains unclear.

Methods

We explored the underlying mechanism by establishing HBV X protein (HBx) overexpressing renal tubular epithelial (HK-2) cells and human podocytes with DNMT1 knockdown. Using RNA-sequencing to determine the downstream targets of DNMT1 and evaluate its levels of promoter methylation. HBV transgenic mice were used to examine the effects of DNMT1 inhibitor on renal in vivo.

Results

DNMT1 was significantly upregulated in the renal tissue of HBV-GN patients, accompanied by injuries of HK-2 cells and podocytes. HBx markedly upregulated DNMT1 and induced epithelial-mesenchymal transition (EMT) and inflammation in HK-2 cells and human podocytes. This increased DNMT1 expression was attenuated after DNMT1 knockdown, accompanied by restored HK-2 cells and podocyte injuries resulting from the activation of PI3K/Akt/mTOR and nuclear factor-kappa B (NF-κB) pathways. Hypermethylation of the phosphatase and tensin homolog (PTEN) promoter and vitamin D receptor (VDR) was induced in HBx-overexpressing HK-2 cells and podocytes, respectively, whereas DNMT1 knockdown effectively corrected these alterations. Furthermore, PTEN and VDR ablation resulted in marked EMT and inflammation induction in HBx-overexpressing HK-2 cells and human podocytes even with DNMT1 knockdown. Downregulation of the PI3K/Akt/mTOR-related pathway attenuated HBx-induced EMT and inflammation in HK-2 cells. Luciferase reporter assay revealed VDR as a direct target of the Snail family transcriptional repressor 1 (SNAI1) in HBx-overexpressing podocytes. DNA methylation inhibitor 5-azacytidine alleviated urinary protein and renal inflammation in HBV transgenic mice via PTEN-PI3K/Akt signaling and VDR signaling axis.

Conclusions

Our study clarifies the potential epigenetic mechanisms underlying HBx-induced renal injuries in HBV-GN and the renoprotective effects of inhibiting DNMT1, which can provide important insights into the development of treatments for HBV-GN.

Low-dose 5-aza-2'-deoxycytidine protects against early renal injury by increasing klotho expression

Aim: To explore the effect of the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine (Aza) on early renal injury. Materials & methods: Cell damage and inflammation are features of early renal injury. The apoptosis and inflammation in hypoxia/reoxygenation (H/R)-induced human proximal tubular epithelial cells (HK-2) and ischemia-reperfusion kidney were studied, and expression of the protein klotho was investigated. Results: Aza induced HK-2 apoptosis in a dose-dependent manner, but low-dose Aza attenuated the apoptosis and inflammation in H/R-induced HK-2 cells and ischemia-reperfusion kidney. Low-dose Aza ameliorated renal function in mice with renal ischemia-reperfusion injury. Meanwhile, low-dose Aza upregulated klotho expression in H/R-induced HK-2 cells and ischemia-reperfusion kidney. Klotho knockdown abrogated the effects of low-dose Aza on apoptosis and inflammation. Conclusion: Low-dose Aza protects against renal early injury by increasing klotho expression.

Epigenetic regulation of Toll-like receptors 2 and 4 in kidney disease

Kidney disease affects more than 10% of the worldwide population and causes significant morbidity and mortality. Epigenetic mechanisms such as DNA methylation, histone modifications, and non-coding RNAs (ncRNAs) play a pivotal role in the progression of kidney disease. These epigenetic mechanisms are reversible and majorly involved in regulating gene expression of inflammatory, fibrotic, and apoptotic proteins. Emerging data suggest that the Toll-like receptor 2 and Toll-like receptor 4 (TLR2 and TLR4) are expressed by almost all types of kidney cells and known for promoting inflammation by recognizing damage-associated molecular proteins (DAMPs). Epigenetic mechanisms regulate TLR2 and TLR4 signaling in various forms of kidney disease where different histone modifications promote the transcription of the TLR2 and TLR4 gene and its ligand high mobility group box protein 1 (HMGB1). Moreover, numerous long non-coding RNAs (LncRNAs) and microRNAs (miRNAs) modulate TLR2 and TLR4 signaling in kidney disease. However, the precise mechanisms behind this regulation are still enigmatic. Studying the epigenetic mechanisms involved in the regulation of TLR2 and TLR4 signaling in the development of kidney disease may help in understanding and finding novel therapeutic strategies. This review discusses the intricate relationship of epigenetic mechanisms with TLR2 and TLR4 in different forms of kidney diseases. In addition, we discuss the different lncRNAs and miRNAs that regulate TLR2 and TLR4 as potential therapeutic targets in kidney disease.

Epigenetics-mediated pathological alternations and their potential in antiphospholipid syndrome diagnosis and therapy

APS (antiphospholipid syndrome) is a systematic autoimmune disease accompanied with venous or arterial thrombosis and poor pregnant manifestations, partly attributing to the successive elevated aPL (antiphospholipid antibodies) and provoked prothrombotic and proinflammatory molecules production. Nowadays, most researches focus on the laboratory detection and clinic features of APS, but its precise etiology remains to be deeply explored. As we all know, the dysfunction of ECs (endothelial cells), monocytes, platelets, trophoblasts and neutrophils are key contributors to APS progression. Especially, their epigenetic variations, mainly including the promoter CpGs methylation, histone PTMs (post-translational modifications) and ncRNAs (noncoding RNAs), result in genes expression or silence engaged in inflammation initiation, thrombosis formation, autoimmune activation and APOs (adverse pregnancy outcomes) in APS. Given the potential of epigenetic markers serving as diagnostic biomarkers or therapeutic targets of APS, and the encouraging advancements in epigenetic drugs are being made. In this review, we would systematically introduce the epigenetic underlying mechanisms for APS progression, comprehensively elucidate the functional mechanisms of epigenetics in boosting ECs, monocytes, platelets, trophoblasts and neutrophils. Lastly, the application of epigenetic alterations for probing novel diagnostic, specific therapeutic and prognostic strategies would be proposed.

Metabolic Regulation of Hepatitis B Virus Infection in HBV-Transgenic Mice

Hepatitis B virus (HBV) infection is a worldwide health burden. Metabolomics analysis has revealed HBV-induced metabolism dysregulation in liver tissues and hepatocytes. However, as an infectious disease, the tissue-specific landscape of metabolic profiles of HBV infection remains unclear. To fill this gap, we applied untargeted nuclear magnetic resonance (NMR) metabolomic analysis of the heart, liver, spleen, lung, kidney, pancreas, and intestine (duodenum, jejunum, ileum) in HBV-transgenic mice and their wild-type littermates. Strikingly, we found systemic metabolic alterations induced by HBV in liver and extrahepatic organs. Significant changes in metabolites have been observed in most tissues of HBV-transgenic mice, except for ileum. The metabolic changes may provide novel therapeutic targets for the treatment of HBV infection. Moreover, tissue-specific metabolic profiles could speed up the study of HBV induced systemic metabolic reprogramming, which could help follow the progression of HBV infection and explain the underlying pathogenesis.

Histone lysine-specific demethylase 1 induced renal fibrosis via decreasing sirtuin 3 expression and activating TGF-β1/Smad3 pathway in diabetic nephropathy

OBJECTIVE

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease. Histone lysine-specific demethylase 1 (LSD1) is a flavin-containing amino oxidase that can repress or activate transcription. The aim of this study is to explore the mechanism of LSD1 aggravating DN-induced renal fibrosis.

METHODS

The STZ-induced DN rat model was established for in vivo study. The rats were divided into four groups: Sham, STZ, STZ + Ad-shNC and Ad-shLSD1. The Hematoxylin-eosin (HE) staining was used to evaluate the renal injury. The Immunofluorescence assay was used to determine the LSD1, Fibronectin and α-SMA expression. The related protein expression was detected by western blot.

RESULTS

Knockdown of LSD1 alleviated STZ-induced renal injury. Moreover, knockdown of LSD1 decreased the expression of serum biochemical markers, containing urine output (24 h), urinary protein (24 h), serum creatinine, BUN and UACR. Furthermore, we proved that knockdown of LSD1 alleviated renal fibrosis in STZ-induced DN rats. In vitro, knockdown of LSD1 suppressed NRK-49F cells activation and overexpression of LSD1 induced renal fibrosis. In addition, knockdown of LSD1 could deactivate TGF-β1/Smad3 pathway and promote sirtuin 3 (SIRT3) expression in vivo and in vitro. The rescue experiments confirmed that LSD1 induced renal fibrosis via decreasing SIRT3 expression and activating TGF-β1/Smad3 pathway.

CONCLUSION

LSD1 deficiency leads to alleviate STZ-induced renal injury and overexpression of LSD1 induces renal fibrosis via decreasing SIRT3 expression and activating TGF-β1/Smad3 pathway, which provides a reasonable strategy for developing novel drugs targeting LDS1 to block renal fibrosis.

Heterochromatin inhibits cGAS and STING during oxidative stress-induced retinal pigment epithelium and retina degeneration

Age-related macular degeneration (AMD) is a leading cause of blindness characterized by degeneration of retina pigment epithelium (RPE) and photoreceptors in the macular region. Activation of the innate immune cGAS-STING signaling has been detected in RPE of dry AMD patients, but the regulatory basis is largely unexplored. Heterochromatin is a highly compact, transcription inert chromatin status. We have recently shown that heterochromatin is required for RPE survival through epigenetically silencing p53-mediated apoptosis signaling. Here, we found that cGAS and STING were dose-dependently upregulated in mouse RPE and retina during oxidative injury, correlated with decreased chromatin compaction in their gene loci. Genetic or pharmaceutical disruption of heterochromatin leads to elevated cGAS and STING expression and enhanced inflammatory response in oxidative stress-induced RPE and retina degeneration. In contrast, application of methotrexate (MTX), a recently identified heterochromatin-promoting drug, inhibits cGAS and STING in both RPE and retina, attenuates RPE/retina degeneration and inflammation. Further, we show that intact heterochromatin is required for MTX to repress cGAS and STING. Together, we demonstrated an unrevealed regulatory function of heterochromatin on cGAS and STING expression and provide potential new therapeutic strategy for AMD treatment.

SCM-198 ameliorates endometrial inflammation via suppressing the LPS-JNK-cJUN/cFOS-TLR4-NF-κB pathway

Endometritis is an inflammatory disease of the endometrium, which is responsible for endometrial dysfunction, decidualization failure, and increased incidence of early pregnancy loss. SCM-198, a synthetic form of leonurine, is well known to possess anti-inflammatory effects. SCM-198 has been reported to display beneficial effects on endometritis. However, the specific mechanisms of SCM-198 in preventing endometritis remain unknown. In this study, we focused on the molecular mechanism of SCM-198 in inhibiting endometritis. The anti-inflammatory effects and the related signaling pathways of SCM-198 were studied in vitro using human endometrial stromal cells (hESCs). Reverse transcriptase-polymerase chain reaction and western blot analysis results demonstrated that SCM-198 markedly inhibited lipopolysaccharide (LPS)-induced endometrial inflammatory response by suppressing the LPS-JNK-cJUN/cFOS-TLR4-NF-κB pathway. The preventive and therapeutic effects of SCM-198 on endometrial inflammation were explored by using a mouse model of LPS-induced endometritis. SCM-198 produced essentially the same effects when administered either post-treatment (after LPS) or pre-treatment (before LPS) via vaginal or intraperitoneal administration. In vivo results indicated that SCM-198 is a potential effective drug for the treatment of endometritis.

Roles of lysine-specific demethylase 1 (LSD1) in homeostasis and diseases

Lysine-specific demethylase 1 (LSD1) targets mono- or di-methylated histone H3K4 and H3K9 as well as non-histone substrates and functions in the regulation of gene expression as a transcriptional repressor or activator. This enzyme plays a pivotal role in various physiological processes, including development, differentiation, inflammation, thermogenesis, neuronal and cerebral physiology, and the maintenance of stemness in stem cells. LSD1 also participates in pathological processes, including cancer as the most representative disease. It promotes oncogenesis by facilitating the survival of cancer cells and by generating a pro-cancer microenvironment. In this review, we discuss the role of LSD1 in several aspects of cancer, such as hypoxia, epithelial-to-mesenchymal transition, stemness versus differentiation of cancer stem cells, as well as anti-tumor immunity. Additionally, the current understanding of the involvement of LSD1 in various other pathological processes is discussed.

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.

In vitro evidence of NLRP3 inflammasome regulation by histone demethylase LSD2 in renal cancer: a pilot study

NLRP3 pathway plays a vital role in the pathogenesis of different human cancers but still the regulation of NLRP3 pathway largely unknown. Therefore, we examined the levels of NLRP3 and its downstream components (caspase-1 and IL-1β) and its relationship with histone modifiers in renal cancer pathogenesis. Total 30 cases of clear cell renal cell carcinoma (ccRCC), were studied for NLRP3, caspase-1 and IL-1β expression using real-time PCR, which showed the augmented levels of all the three components of NLRP3 inflammasome pathway in ccRCC. Next, role of the FAD dependent monoamine oxidases (LSD2) and jumonji C (JmjC)-domain-containing, iron-dependent dioxygenases (KDM5A) histone demethylases were evaluated in regulation of NLRP3 inflammasome pathway in-vitro using RCC cell line. It was observed that silencing of KDM5A didn't alter the levels of neither of the NLRP3 component but inhibition of LSD2 showed significant effect on NLRP3 expression while no change in caspase-1 and IL-1β levels. This study suggests that rather LSD2 not KDM5A lysine demethylase family might be involved in the regulation of NLRP3 inflammasome in cancer cells which could be useful for deciphering the future therapeutic targets for the disease.

Histone lysine specific demethylase 1 inhibitors

LSD1 plays a pivotal role in numerous biological functions. The overexpression of LSD1 is reported to be associated with different malignancies. Over the last decade, LSD1 has emerged as an interesting target for the treatment of acute myeloid leukaemia (AML). Numerous researchers have designed, synthesized, and evaluated various LSD1 inhibitors with diverse chemical architectures. Some of these inhibitors have entered clinical trials and are currently at different phases of clinical evaluation. This comprehensive review enlists recent research developments in LSD1 targeting pharmacophores reported over the last few years.

Emerging of lysine demethylases (KDMs): From pathophysiological insights to novel therapeutic opportunities

In recent years, there have been remarkable scientific advancements in the understanding of lysine demethylases (KDMs) because of their demethylation of diverse substrates, including nucleic acids and proteins. Novel structural architectures, physiological roles in the gene expression regulation, and ability to modify protein functions made KDMs the topic of interest in biomedical research. These structural diversities allow them to exert their function either alone or in complex with numerous other bio-macromolecules. Impressive number of studies have demonstrated that KDMs are localized dynamically across the cellular and tissue microenvironment. Their dysregulation is often associated with human diseases, such as cancer, immune disorders, neurological disorders, and developmental abnormalities. Advancements in the knowledge of the underlying biochemistry and disease associations have led to the development of a series of modulators and technical compounds. Given the distinct biophysical and biochemical properties of KDMs, in this review we have focused on advances related to the structure, function, disease association, and therapeutic targeting of KDMs highlighting improvements in both the specificity and efficacy of KDM modulation.