KDM5A/B contribute to HIV-1 latent infection and survival of HIV-1 infected cells

Combinational antiretroviral therapy (cART) suppresses human immunodeficiency virus type 1 (HIV-1) viral replication and pathogenesis in acquired immunodeficiency syndrome (AIDS) patients. However, HIV-1 remains in the latent stage of infection by suppressing viral transcription, which hinders an HIV-1 cure. One approach for an HIV-1 cure is the "shock and kill" strategy. The strategy focuses on reactivating latent HIV-1, inducing the viral cytopathic effect and facilitating the immune clearance for the elimination of latent HIV-1 reservoirs. Here, we reported that the H3K4 trimethylation (H3K4me3)-specific demethylase KDM5A/B play a role in suppressing HIV-1 Tat/LTR-mediated viral transcription in HIV-1 latent cells. Furthermore, we evaluated the potential of KDM5-specific inhibitor JQKD82 as an HIV-1 "shock and kill" agent. Our results showed that JQKD82 increases the H3K4me3 level at HIV-1 5' LTR promoter regions, HIV-1 reactivation, and the cytopathic effects in an HIV-1-latent T cell model. In addition, we identified that the combination of JQKD82 and AZD5582, a non-canonical NF-κB activator, generates a synergistic impact on inducing HIV-1 lytic reactivation and cell death in the T cell. The latency-reversing potency of the JQKD82 and AZD5582 pair was also confirmed in peripheral blood mononuclear cells (PBMCs) isolated from HIV-1 aviremic patients and in an HIV-1 latent monocyte. In latently infected microglia (HC69) of the brain, either deletion or inhibition of KDM5A/B results in a reversal of the HIV-1 latency. Overall, we concluded that KDM5A/B function as a host repressor of the HIV-1 lytic reactivation and thus promote the latency and the survival of HIV-1 infected reservoirs.

Tumor microenvironment restricts IL-10 induced multipotent progenitors to myeloid-lymphatic phenotype

Lymphangiogenesis is induced by local pro-lymphatic growth factors and bone marrow (BM)-derived myeloid-lymphatic endothelial cell progenitors (M-LECP). We previously showed that M-LECP play a significant role in lymphangiogenesis and lymph node metastasis in clinical breast cancer (BC) and experimental BC models. We also showed that differentiation of mouse and human M-LECP can be induced through sequential activation of colony stimulating factor-1 (CSF-1) and Toll-like receptor-4 (TLR4) pathways. This treatment activates the autocrine interleukin-10 (IL-10) pathway that, in turn, induces myeloid immunosuppressive M2 phenotype along with lymphatic-specific proteins. Because IL-10 is implicated in differentiation of numerous lineages, we sought to determine whether this pathway specifically promotes the lymphatic phenotype or multipotent progenitors that can give rise to M-LECP among other lineages. Analyses of BM cells activated either by CSF-1/TLR4 ligands in vitro or orthotopic breast tumors in vivo showed expansion of stem/progenitor population and coincident upregulation of markers for at least four lineages including M2-macrophage, lymphatic endothelial, erythroid, and T-cells. Induction of cell plasticity and multipotency was IL-10 dependent as indicated by significant reduction of stem cell markers and those for multiple lineages in differentiated cells treated with anti-IL-10 receptor (IL-10R) antibody or derived from IL-10R knockout mice. However, multipotent CD11b+/Lyve-1+/Ter-119+/CD3e+ progenitors detected in BM appeared to split into a predominant myeloid-lymphatic fraction and minor subsets expressing erythroid and T-cell markers upon establishing tumor residence. Each sub-population was detected at a distinct intratumoral site. This study provides direct evidence for differences in maturation status between the BM progenitors and those reaching tumor destination. The study results suggest preferential tumor bias towards expansion of myeloid-lymphatic cells while underscoring the role of IL-10 in early BM production of multipotent progenitors that give rise to both hematopoietic and endothelial lineages.

Transcriptomic changes in the microsporidia proliferation and host responses in congenitally infected embryos and larvae

Congenital infection caused by vertical transmission of microsporidia N. bombycis can result in severe economic losses in the silkworm-rearing industry. Whole-transcriptome analyses have revealed non-coding RNAs and their regulatory networks in N. bombycis infected embryos and larvae. However, transcriptomic changes in the microsporidia proliferation and host responses in congenitally infected embryos and larvae remains unclear. Here, we simultaneously compared the transcriptomes of N. bombycis and its host B. mori embryos of 5-day and larvae of 1-, 5- and 10-day during congenital infection. For the transcriptome of N. bombycis, a comparison of parasite expression patterns between congenital-infected embryos and larva showed most genes related to parasite central carbon metabolism were down-regulated in larvae during infection, whereas the majority of genes involved in parasite proliferation and growth were up-regulated. Interestingly, a large number of distinct or shared differentially expressed genes (DEGs) were revealed by the Venn diagram and heat map, many of them were connected to infection related factors such as Ricin B lectin, spore wall protein, polar tube protein, and polysaccharide deacetylase. For the transcriptome of B. mori infected with N. bombycis, beyond numerous DEGs related to DNA replication and repair, mRNA surveillance pathway, RNA transport, protein biosynthesis, and proteolysis, with the progression of infection, a large number of DEGs related to immune and infection pathways, including phagocytosis, apoptosis, TNF, Toll-like receptor, NF-kappa B, Fc epsilon RI, and some diseases, were successively identified. In contrast, most genes associated with the insulin signaling pathway, 2-oxacarboxylic acid metabolism, amino acid biosynthesis, and lipid metabolisms were up-regulated in larvae compared to those in embryos. Furthermore, dozens of distinct and three shared DEGs that were involved in the epigenetic regulations, such as polycomb, histone-lysine-specific demethylases, and histone-lysine-N-methyltransferases, were identified via the Venn diagram and heat maps. Notably, many DEGs of host and parasite associated with lipid-related metabolisms were verified by RT-qPCR. Taken together, simultaneous transcriptomic analyses of both host and parasite genes lead to a better understanding of changes in the microsporidia proliferation and host responses in embryos and larvae in N. bombycis congenital infection.

Exploring host epigenetic enzymes as targeted therapies for visceral leishmaniasis: in silico design and in vitro efficacy of KDM6B and ASH1L inhibitors

In order to combat various infectious diseases, the utilization of host-directed therapies as an alternative to chemotherapy has gained a lot of attention in the recent past, since it bypasses the existing limitations of conventional therapies. The use of host epigenetic enzymes like histone lysine methyltransferases and lysine demethylases as potential drug targets has successfully been employed for controlling various inflammatory diseases like rheumatoid arthritis and acute leukemia. In our earlier study, we have already shown that the functional knockdown of KDM6B and ASH1L in the experimental model of visceral leishmaniasis has resulted in a significant reduction of organ parasite burden. Herein, we performed a high throughput virtual screening against KDM6B and ASH1L using > 53,000 compounds that were obtained from the Maybridge library and PubChem Database, followed by molecular docking to evaluate their docking score/Glide Gscore. Based on their docking scores, the selected inhibitors were later assessed for their in vitro anti-leishmanial efficacy. Out of all inhibitors designed against KDM6B and ASH1L, HTS09796, GSK-J4 and AS-99 particularly showed promising in vitro activity with IC50 < 5 µM against both extracellular promastigote and intracellular amastigote forms of L. donovani. In vitro drug interaction studies of these inhibitors further demonstrated their synergistic interaction with amphotericin-B and miltefosine. However, GSK-J4 makes an exception by displaying an in different mode of interaction with miltefosine. Collectively, our in silico and in vitro studies acted as a platform to identify the applicability of these inhibitors targeted against KDM6B and ASH1L for anti-leishmanial therapy.

SMYD2 Imparts Gemcitabine Resistance to Pancreatic Adenocarcinoma Cells by Upregulating EVI2A

Although gemcitabine (GEM) is the first‑line drug for advanced pancreatic adenocarcinoma (PAAD), the development of GEM resistance severely limits the effectiveness of this chemotherapy. This study investigated the mechanisms of ecotropic viral integration site 2 A (EVI2A) for resistance to GEM and immune evasion in PAAD. GEM resistance-related biomarkers were predicted using GEO datasets, and GEM-resistant PAAD cells were generated. EVI2A was found expressed highly in GEM-resistant PAAD cells. Gain-of-function analyses revealed that EVI2A encouraged the proliferation and motility of GEM-resistant cells and prevented apoptosis. In addition, EVI2A reduced T cell effector activation. SMYD2 was overexpressed in GEM-resistant cells, and SMYD2 enhanced H3K36me2 modification of EVI2A, thereby promoting EVI2A expression. SMYD2 reduced the sensitivity of GEM-resistant cells, which was reversed by EVI2A knockdown. SMYD2 increased the amount of M2 macrophages (co-cultured with PAAD cells) and decreased T cell effector activation (co-cultured with macrophage supernatant), and the number of M2 macrophages was decreased and T cell effectors were activated following EVI2A knockdown. Our findings indicate that EVI2A, manipulated by the SMYD2-H3K36me2 epigenetic axis, promoted GEM resistance and M2 macrophage-mediated immune evasion in PAAD. Therefore, EVI2A might represent a therapeutic target for overcoming GEM resistance and immunosuppressive environment in PAAD.

Echinococcus granulosus cyst fluid inhibits inflammatory responses through inducing histone demethylase KDM5B in macrophages

BACKGROUND

Echinococcus granulosus cyst fluid (EgCF) weakens macrophage inflammatory responses, thereby enabling the parasite to evade the immune system. However, the role of histone modification in this process remains to be explored.

METHODS

The levels of IL-6, TNF-α, IL-10, H3K4me3, and KDM5B were detected using quantitative real-time PCR, ELISA, and Western blotting. The enrichment of H3K4me3 and KDM5B at the promoter of inflammatory factors was detected by chromatin immunoprecipitation.

RESULTS

Based on EgCF-stimulated macrophage models, we found that EgCF significantly inhibited mRNA expression and protein secretion of IL-6 and TNF-α and upregulated mRNA expression of IL-10 under the influence of TLR4. EgCF lowered the level of H3K4me3 and promoted the transcription and protein stability of histone demethylase KDM5B. Chromatin immunoprecipitation analysis revealed that EgCF suppressed the enrichment of H3K4me3 modification at the promoters of TNF-α and IL-6 and downregulated their expression in macrophages. Additionally, the inhibition of KDM5B activity by CPI-455 weakened the anti-inflammatory effect of EgCF.

CONCLUSIONS

Our findings demonstrate a novel mechanism through which EgCF promotes KDM5B expression and inhibits the enrichment of H3K4me3 at the promoters of inflammatory cytokines to suppress the inflammatory response.

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.

A Systematic Review of Apicomplexa Looking into Epigenetic Pathways and the Opportunity for Novel Therapies

Interest in host epigenetic changes during apicomplexan infections increased in the last decade, mainly due to the emergence of new therapies directed to these alterations. This review aims to carry out a bibliometric analysis of the publications related to host epigenetic changes during apicomplexan infections and to summarize the main studied pathways in this context, pointing out those that represent putative drug targets. We used four databases for the article search. After screening, 116 studies were included. The bibliometric analysis revealed that the USA and China had the highest number of relevant publications. The evaluation of the selected studies revealed that Toxoplasma gondii was considered in most of the studies, non-coding RNA was the most frequently reported epigenetic event, and host defense was the most explored pathway. These findings were reinforced by an analysis of the co-occurrence of keywords. Even though we present putative targets for repurposing epidrugs and ncRNA-based drugs in apicomplexan infections, we understand that more detailed knowledge of the hosts' epigenetic pathways is still needed before establishing a definitive drug target.

The paradigm of intracellular parasite survival and drug resistance in leishmanial parasite through genome plasticity and epigenetics: Perception and future perspective

Leishmania is an intracellular, zoonotic, kinetoplastid eukaryote with more than 1.2 million cases all over the world. The leishmanial chromosomes are divided into polymorphic chromosomal ends, conserved central domains, and antigen-encoding genes found in telomere-proximal regions. The genome flexibility of chromosomal ends of the leishmanial parasite is known to cause drug resistance and intracellular survival through the evasion of host defense mechanisms. Therefore, in this review, we discuss the plasticity of Leishmania genome organization which is the primary cause of drug resistance and parasite survival. Moreover, we have not only elucidated the causes of such genome plasticity which includes aneuploidy, epigenetic factors, copy number variation (CNV), and post-translation modification (PTM) but also highlighted their impact on drug resistance and parasite survival.

Emerging strategies and challenges of molecular therapeutics in antileishmanial drug development

Molecular therapy refers to targeted therapies based on molecules which have been intelligently directed towards specific biomolecular structures and include small molecule drugs, monoclonal antibodies, proteins and peptides, DNA or RNA-based strategies, targeted chemotherapy and nanomedicines. Molecular therapy is emerging as the most effective strategy to combat the present challenges of life-threatening visceral leishmaniasis, where the successful human vaccine is currently unavailable. Moreover, current chemotherapy-based strategies are associated with the issues of ineffective targeting, unavoidable toxicities, invasive therapies, prolonged treatment, high treatment costs and the development of drug-resistant strains. Thus, the rational approach to antileishmanial drug development primarily demands critical exploration and exploitation of biochemical differences between host and parasite biology, immunocharacteristics of parasite homing, and host-parasite interactions at the molecular/cellular level. Following this, the novel technology-based designing and development of host and/or parasite-targeted therapeutics having leishmanicidal and immunomodulatory activity is utmost essential to improve treatment efficacy. Thus, the present review is focused on immunological and molecular checkpoint targets in host-pathogen interaction, and molecular therapeutic prospects for Leishmania intervention, and the challenges ahead.

Leishmania donovani Impedes Antileishmanial Immunity by Suppressing Dendritic Cells via the TIM-3 Receptor

An immunological hallmark of visceral leishmaniasis (VL), caused by Leishmania donovani, is profound immunosuppression. However, the molecular basis for this immune dysfunction has remained ill defined. Since dendritic cells (DCs) normally initiate antileishmanial immune responses, we investigated whether DCs are dysregulated during L. donovani infection and assessed its role in immunosuppression. Accordingly, we determined the regulatory effect of L. donovani on DCs. Notably, it is still unclear whether L. donovani activates or suppresses DCs. In addition, the molecular mechanism and the relevant receptor (or receptors) mediating the immunoregulatory effect of L. donovani on DCs are largely undefined. Here, we report that L. donovani inhibited DC activation/maturation by transmitting inhibitory signals through the T cell immunoglobulin and mucin protein-3 (TIM-3) receptor and thereby suppressed antileishmanial immune responses. L. donovani in fact triggered TIM-3 phosphorylation in DCs, which in turn recruited and activated a nonreceptor tyrosine kinase, Btk. Btk then inhibited DC activation/maturation by suppressing the NF-κB pathway in an interleukin-10 (IL-10)-dependent manner. Treatment with TIM-3-specific blocking antibody or suppressed expression of TIM-3 or downstream effector Btk made DCs resistant to the inhibitory effects of L. donovani. Adoptive transfer experiments further demonstrated that TIM-3-mediated L. donovani-induced inhibition of DCs plays a crucial role in the suppression of the antileishmanial immune response in vivo. These findings identify TIM-3 as a new regulator of the antileishmanial immune response and demonstrate a unique mechanism for host immunosuppression associated with L. donovani infection. IMPORTANCE Visceral leishmaniasis (VL), a poverty-related disease caused by Leishmania donovani, is ranked by the World Health Organization as the second largest killer parasitic disease in the world. The protective immune response against VL is primarily regulated by dendritic cells (DCs), which upon activation/maturation initiate an antileishmanial immune response. However, it remains obscure whether L. donovani promotes or inhibits DC activation. In addition, the receptor through which L. donovani exerts immunoregulatory effect on DCs is ill defined. Here, we for the first time report that L. donovani inhibits DC activation and maturation via the T cell immunoglobulin and mucin protein-3 (TIM-3) receptor and thereby attenuates the capacity of DCs to trigger antileishmanial immune responses in vivo. In fact, we demonstrate here that suppression of TIM-3 expression in DCs augments antileishmanial immunity. Our study uncovers a unique mechanism by which L. donovani subverts host immune responses and suggests TIM-3 as a potential new target for immunotherapy against VL.

DNA methylation alterations caused by Leishmania infection may generate a microenvironment prone to tumour development

DNA methylation is an epigenetic signature consisting of a methyl group at the 5’ cytosine of CpG dinucleotides. Modifications in DNA methylation pattern have been detected in cancer and infectious diseases and may be associated with gene expression changes. In cancer development DNA methylation aberrations are early events whereas in infectious diseases these epigenetic changes may be due to host/pathogen interaction. In particular, in leishmaniasis, a parasitic disease caused by the protozoan Leishmania, DNA methylation alterations have been detected in macrophages upon infection with Leishmania donovani and in skin lesions from patients with cutaneous leishmaniasis. Interestingly, different types of cancers, such as cutaneous malignant lesions, lymphoma and hepatocellular carcinoma, have been diagnosed in patients with a history of leishmaniasis. In fact, it is known that there exists an association between cancer and infectious diseases. Leishmania infection may increase susceptibility to develop cancer, but the mechanisms involved are not entirely clear. Considering these aspects, in this review we discuss the hypothesis that DNA methylation alterations induced by Leishmania may trigger tumorigenesis in long term infection since these epigenetic modifications may enhance and accumulate during chronic leishmaniasis.

Nucleosome Structures Built from Highly Divergent Histones: Parasites and Giant DNA Viruses

In eukaryotes, genomic DNA is bound with histone proteins and packaged into chromatin. The nucleosome, a fundamental unit of chromatin, regulates the accessibility of DNA to enzymes involved in gene regulation. During the past few years, structural analyses of chromatin architectures have been limited to evolutionarily related organisms. The amino acid sequences of histone proteins are highly conserved from humans to yeasts, but are divergent in the deeply branching protozoan groups, including human parasites that are directly related to human health. Certain large DNA viruses, as well as archaeal organisms, contain distant homologs of eukaryotic histone proteins. The divergent sequences give rise to unique and distinct nucleosome architectures, although the fundamental principles of histone folding and DNA contact are highly conserved. In this article, we review the structures and biophysical properties of nucleosomes containing histones from the human parasites Giardia lamblia and Leishmania major, and histone-like proteins from the Marseilleviridae amoeba virus family. The presented data confirm the sharing of the overall DNA compaction system among evolutionally distant species and clarify the deviations from the species-specific nature of the nucleosome.

Activation of TLR-pathway to induce host Th1 immune respons eagainst visceral leishmaniasis: Involvement of galactosylated-flavonoids

Immunotherapeutic strategies against visceral leishmaniasis (VL) are pertinent because of the emergence of resistance against existing chemotherapy, coupled with their toxicity and high costs. Various bioactive components with potential immunomodulatory activity, such as alkaloids, terpenes, saponins, flavonoids obtained primarily from medicinal plants, have been screened against different disease models. Reports suggested that glycans containing terminal β-galactose can skew host immune response towards Th1 by engaging TLRs. In this study, two synthesized terminal galactose-containing flavones, Quercetin 3-d-galactoside (Q-gal) and Kaempferol 3-O-d-galactoside (K-gal), are profiled in terms of inducing host protective Th1 response in both in vitro & in vivo animal models of experimental VL individually against antimony-resistant & antimony-susceptible Leishmania donovani. Further, we explored that both Q-gal and K-gal induce TLR4 mediated Th1 response to encounter VL. Molecular docking analysis also suggested strong interaction with TLR4 for both the galactosides, with a slightly better binding potential towards Q-gal. Treatment with both Q-gal and K-gal showed significant antileishmanial efficacy. Each considerably diminished the liver and splenic parasite burden 60 days after post-infection (>90% in AG83 infected mice and >87% in GE1F8R infected mice) when administered at a 5 mg/kg/day body-weight dose for ten consecutive days. However, the treatments failed to clear the parasites in the TLR4 deficient C3H/HeJ mice. Treatment with these compounds favors the elevation of TLR4 dependent host protective Th1 cytokines and suppression of disease-promoting IL-10. Q-gal and K-gal also triggered sufficient ROS generation in macrophages to kill intracellular parasites directly.

•

Galactosilated flavonoids treatment clears in-vivo drug-resistant Leishmania donovani infection.

•

Quercetin 3-d-galactoside (Q-gal) & Kaempferol 3-O-d-galactoside (K-gal) induce host TLR4 pathway.

•

These flavonoids up-regulate Th1 cytokines and suppress the disease-promoting IL-10.

•

TLR4 deficient C3H/HeJ mice are unresponsive towards Q-gal and K-gal treatment.

The Pathogenicity and Virulence of Leishmania - interplay of virulence factors with host defenses

Leishmaniasis is a group of disease caused by the intracellular protozoan parasite of the genus Leishmania. Infection by different species of Leishmania results in various host immune responses, which usually lead to parasite clearance and may also contribute to pathogenesis and, hence, increasing the complexity of the disease. Interestingly, the parasite tends to reside within the unfriendly environment of the macrophages and has evolved various survival strategies to evade or modulate host immune defense. This can be attributed to the array of virulence factors of the vicious parasite, which target important host functioning and machineries. This review encompasses a holistic overview of leishmanial virulence factors, their role in assisting parasite-mediated evasion of host defense weaponries, and modulating epigenetic landscapes of host immune regulatory genes. Furthermore, the review also discusses the diagnostic potential of various leishmanial virulence factors and the advent of immunomodulators as futuristic antileishmanial drug therapy.

Inhibition of Histone H3 Lysine-27 Demethylase Activity Relieves Rheumatoid Arthritis Symptoms via Repression of IL6 Transcription in Macrophages

Rheumatoid arthritis (RA) occurs in about 5 per 1,000 people and can lead to severe joint damage and disability. However, the knowledge of pathogenesis and treatment for RA remains limited. Here, we found that histone demethylase inhibitor GSK-J4 relieved collagen induced arthritis (CIA) symptom in experimental mice model, and the underlying mechanism is related to epigenetic transcriptional regulation in macrophages. The role of epigenetic regulation has been introduced in the process of macrophage polarization and the pathogenesis of inflammatory diseases. As a repressive epigenetic marker, tri-methylation of lysine 27 on histone H3 (H3K27me3) was shown to be important for transcriptional gene expression regulation. Here, we comprehensively analyzed H3K27me3 binding promoter and corresponding genes function by RNA sequencing in two differentially polarized macrophage populations. The results revealed that H3K27me3 binds on the promoter regions of multiple critical cytokine genes and suppressed their transcription, such as IL6, specifically in M-CSF derived macrophages but not GM-CSF derived counterparts. Our results may provide a new approach for the treatment of inflammatory and autoimmune disorders.

Host–Pathogen Interaction in Leishmaniasis: Immune Response and Vaccination Strategies

Leishmaniasis is a zoonotic and vector-borne infectious disease that is caused by the genus Leishmania belonging to the trypanosomatid family. The protozoan parasite has a digenetic life cycle involving a mammalian host and an insect vector. Leishmaniasisis is a worldwide public health problem falling under the neglected tropical disease category, with over 90 endemic countries, and approximately 1 million new cases and 20,000 deaths annually. Leishmania infection can progress toward the development of species–specific pathologic disorders, ranging in severity from self-healing cutaneous lesions to disseminating muco-cutaneous and fatal visceral manifestations. The severity and the outcome of leishmaniasis is determined by the parasite’s antigenic epitope characteristics, the vector physiology, and most importantly, the immune response and immune status of the host. This review examines the nature of host–pathogen interaction in leishmaniasis, innate and adaptive immune responses, and various strategies that have been employed for vaccine development.

Computational System Level Approaches for Discerning Reciprocal Regulation of IL10 and IL12 in Leishmaniasis

IL12 and IL10 are two of the major cytokines which control the fate of Leishmaniasis. This paper presents two models healthy state and diseased state which shows how secretion of IL12 is responsible for parasite elimination and IL10 can jeopardize the parasite elimination and promote its survival. Epigenetic modification in the host IL12 and IL10 promoter can decide the fate of parasites. It was observed that reciprocal relationship exists between IL12 and IL10 and that is majorly controlled by a transcription factor NFAT5 from Rel family of transcription factors. By targeting this transcription factor at the cellular level, it might be possible to modulate the release of powerful pro-inflammatory cytokines, thereby reducing parasite survival. The mathematical models developed here serves as a step towards finding a key component that can pave a way for therapeutic investigation.

Mechanobiology of immune cells: Messengers, receivers and followers in leishmaniasis aiding synthetic devices

Cytokines are influential molecules which can direct cells behavior. In this review, cytokines are referred as messengers, immune cells which respond to cytokine stimulus are referred as receivers and the immune cells which gets modulated due to their plasticity induced by infectious pathogen leishmania, are referred as followers. The advantage of plasticity of cells is taken by the parasite to switch them from parasite eliminating form to parasite survival favoring form through a process called as reciprocity which is undergone by cytokines, wherein pro-inflammatory to anti-inflammatory switch occur rendering immune cell population to switch their phenotype. Detailed study of this switch can help in identification of important targets which can help in restoring the phenotype to parasite eliminating form and this can be done through synthetic circuit, finding its wider applicability in therapeutics.

•

Cytokines as messengers for governing reciprocity in infection.

•

Leishmania induces reciprocity modulating the immune cells plasticity.

•

Reciprocity of cytokines identifies important target for therapeutics.

•

Therapeutic targets aiding the design of synthetic devices to combat infection.

Effects of the Lysine Methyltransferase Inhibitor AZ505 on Bone Metabolism

Background

Protein methylation has important role in regulating diverse cellular responses, including differentiation, by affecting protein activity, stability, and interactions. AZ505 is an inhibitor of the SET and MYND domain-containing protein 2 lysine methylase. In this study, we investigated the effect of AZ505 on osteoblast and osteoclast differentiation in vitro and evaluated the effect of AZ505 in vivo on the long bones in mice.

Methods

Osteoblast differentiation was assessed by alkaline phosphatase (ALP) and Alizarin red staining after culturing calvarial preosteoblasts in an osteogenic medium. Osteoclast differentiation was analyzed by tartrate-resistant acid phosphatase (TRAP) staining in bone marrow-derived macrophages cultured with macrophage-colony stimulating factor and receptor activator of nuclear factor-κB ligand (RANKL). For in vivo experiments, mice were intraperitoneally injected with AZ505 and femurs were examined by micro-computed tomography.

Results

AZ505 increased ALP and Alizarin red staining in cultured osteoblasts and the expression of osteoblast marker genes, including Runx2 and osteocalcin. AZ505 resulted in decreased TRAP-staining of osteoclasts and expression of c-Fos and nuclear factor of activated T cells transcription factors and osteoclast marker genes, including cathepsin K and dendritic cell-specific transmembrane protein. Unexpectedly, in vivo administration of AZ505 markedly decreased the trabecular bone mass of femurs. In support of this catabolic result, AZ505 strongly upregulated RANKL expression in osteoblasts.

Conclusions

The results indicate that AZ505 has a catabolic effect on bone metabolism in vivo despite its anabolic effect in bone cell cultures. The findings indicate that cell culture data should be extrapolated cautiously to in vivo outcomes for studying bone metabolism.

Interferon-γ-Producing CD4+ T Cells Drive Monocyte Activation in the Bone Marrow During Experimental Leishmania donovani Infection

Ly6C^hi inflammatory monocytes develop in the bone marrow and migrate to the site of infection during inflammation. Upon recruitment, Ly6C^hi monocytes can differentiate into dendritic cells or macrophages. According to the tissue environment they can also acquire different functions. Several studies have described pre-activation of Ly6C^hi monocytes in the bone marrow during parasitic infection, but whether this process occurs during experimental visceral leishmaniasis and, if so, the mechanisms contributing to their activation are yet to be established. In wild type C57BL/6 (B6) mice infected with Leishmania donovani, the number of bone marrow Ly6C^hi monocytes increased over time. Ly6C^hi monocytes displayed a highly activated phenotype from 28 days to 5 months post infection (p.i), with >90% expressing MHCII and >20% expressing iNOS. In comparison, in B6.Rag2^-/- mice <10% of bone marrow monocytes were MHCII⁺ at day 28 p.i., an activation deficiency that was reversed by adoptive transfer of CD4⁺ T cells. Depletion of CD4⁺ T cells in B6 mice and the use of mixed bone marrow chimeras further indicated that monocyte activation was driven by IFNγ produced by CD4⁺ T cells. In B6.Il10^-/- mice, L. donovani infection induced a faster but transient activation of bone marrow monocytes, which correlated with the magnitude of CD4⁺ T cell production of IFNγ and resolution of the infection. Under all of the above conditions, monocyte activation was associated with greater control of parasite load in the bone marrow. Through reinfection studies in B6.Il10^-/- mice and drug (AmBisome^®) treatment of B6 mice, we also show the dependence of monocyte activation on parasite load. In summary, these data demonstrate that during L. donovani infection, Ly6C^hi monocytes are primed in the bone marrow in a process driven by CD4⁺ T cells and whereby IFNγ promotes and IL-10 limits monocyte activation and that the presence of parasites/parasite antigen plays a crucial role in maintaining bone marrow monocyte activation.

Novel insights into SMYD2 and SMYD3 inhibitors: from potential anti-tumoural therapy to a variety of new applications

The revelance of the epigenetic regulation of cancer led to the design and testing of many drugs targeting epigenetic modifiers. The Su(Var)3-9, Enhancer-of-zeste and Trithorax (SET) and myeloid, Nervy, and DEAF-1 (MYND) domain-containing protein 2 (SMYD2) and 3 (SMYD3) are methyltransferases which act on histone and non-histone proteins to promote tumorigenesis in many cancer types. In addition to their oncogenic roles, SMYD2 and SMYD3 are involved in many other physiopathological conditions. In this review we will focus on the advances made in the last five years in the field of pharmacology regarding drugs targeting SMYD2 (such as LLY-507 or AZ505) and SMYD3 (such as BCI-121 or EPZ031686) and their potential cellular and molecular mechanisms of action and application in anti-tumoural therapy and/or against other diseases.

Critical roles of SMYD2 lysine methyltransferase in mediating renal fibroblast activation and kidney fibrosis

SET and MYND domain protein 2 (SMYD2) is a lysine methyltransferase that mediates histone H3 lysine 36 trimethylation (H3K36me3) and acts as a regulator of tumorgenesis and cystic growth. However, its role in renal fibrosis remains unknown. In this study, we found that SMYD2 was highly expressed in the murine kidney of renal fibrosis induced by unilateral ureteral obstruction, and primarily located in interstitial fibroblasts and renal tubular epithelial cells. Pharmacological inhibition of SMYD2 with AZ505, a highly selective inhibitor of SMYD2, protected against renal fibrosis and inhibited activation/proliferation of renal interstitial fibroblasts and conversion of epithelial cells to a profibrotic phenotype in this model. In cultured renal interstitial fibroblasts, treatment with AZ505 or silencing of SMYD2 by specific siRNA also inhibited serum- or TGF-β1-induced activation and proliferation of renal interstitial fibroblasts. Mechanistic studies showed that SMYD2 inhibition reduced phosphorylation of several profibrotic signaling molecules, including Smad3, extracellular signal-regulated kinase 1/2, AKT, signal transducer and activator of transcription-3 and nuclear factor-κB in both injured kidney and cultured renal fibroblasts. AZ505 was also effective in suppressing renal expression of Snail and Twist, two transcriptional factors that mediate renal partial epithelial-mesenchymal transition and fibrosis. Conversely, AZ505 treatment prevented downregulation of Smad7, a renoprotective factor in vivo and in vitro. These results indicate that SMYD2 plays a critical role in mediating conversion of epithelial cells to a profibrotic phenotype, renal fibroblast activation and renal fibrogenesis, and suggest that SMYD2 may be a potential target for the treatment of chronic fibrosis in kidney disease.

The SMYD family proteins in immunology: An update of their obvious and non-obvious relations with the immune system

Epigenetics is an emerging field, due to its relevance in the regulation of a wide range of biological processes. The Su(Var)3–9, Enhancer-of-zeste and Trithorax (SET) and Myeloid, Nervy, and DEAF-1 (MYND) domain-containing (SMYD) proteins, named SMYD1, SMYD2, SMYD3, SMYD4 and SMYD5, are enzymes that catalyse methylation of histone and non-histone substrates, thereby playing a key role in gene expression regulation in many biological contexts, such as muscle development and physiology, haematopoiesis and many types of cancer. This review focuses on a relatively unexplored aspect of SMYD family members - their relation with immunology. Here, immunology is defined in the broadest sense of the word, including basic research on macrophage function or host immunity against pathogen infection, as well as clinical studies, most of which are centred on blood cancers.

Host immune response against leishmaniasis and parasite persistence strategies: A review and assessment of recent research

Leishmaniasis, a neglected parasitic disease caused by a unicellular protozoan of the genus Leishmania, is transmitted through the bite of a female sandfly. The disease remains a major public health problem and is linked to tropical and subtropical regions, with an endemic picture in several regions, including East Africa, the Mediterranean basin and South America. The different causative species display a diversity of clinical presentations; therefore, the immunological data on leishmaniasis are both scarce and controversial for the different forms and infecting species of the parasite. The present review highlights the main immune parameters associated with leishmaniasis that might contribute to a better understanding of the pathogenicity of the parasite and the clinical outcomes of the disease. Our aim was to provide a concise overview of the immunobiology of the disease and the factors that influence it, as this knowledge may be helpful in developing novel chemotherapeutic and vaccine strategies.

Super enhancer-mediated transcription of miR146a-5p drives M2 polarization during Leishmania donovani infection

The outcome of Leishmania donovani infection depends upon the dynamic interchanges between M1 and M2 macrophages. Information of the involvement of microRNAs (miRNAs) and epigenetic modifiers in regulating macrophage plasticity during L. donovani infection is still elusive. Differential expression analysis of polarization-regulating miRNAs, revealed significant enrichment of miR146a-5p during Leishmania donovani infection. A sustained enrichment of miR146a-5p was observed in both infected bone marrow derived macrophages (BMDMs) and BALB/c mice organs. We found involvement of miR146a-5p in phagocytosis and survivability of parasites. Moreover, miR146a-5pgot enriched in interleukin 4- stimulated BMDMs, indicating its possible involvement in M2 polarization. Upon transfecting BMDMs with miRVANA anti-146a oligos, M2 markers (CCR7, YM-1, FIZZ-1, arginase-1, IL10 and IL4) and transcription factors (p-STAT6 and c/EBPβ) got depleted with concomitant augmentation of M1-polarizing transcription factors (p-STAT1, AP1 and IRF-1), miR146a target genes (TRAF6 and IRAK1), M1 cytokines (IL12 and TNFα), iNOS, nitric oxide, and nuclear translocation of phospho p-65 subunit. Neutralization of intracellular mature miR146a-5p pool in infected BALB/c mice lower organ parasite burden and expressions of M2 markers and IL10 with enrichment of M1 markers like iNOS and IL12. Additionally, we explored the novel role of super enhancer (SE), a cis-acting regulatory component, to enrich miR146a-5p expression during infection. Enhanced expression and nuclear retention of SE components like BET bromodomain 4 (BRD4) and p300 were found in infected BMDMs. Upon silencing BRD4, expressions of miR146a-5p and M2 markers were down regulated and TRAF6, IRAK1 and iNOS levels increased. STRING V.11 based predication and immune precipitation confirmed the strong interaction amongst BRD4, p300 and RNA pol II (RpbI). Chromatin immune precipitation studies suggested the recruitment of BRD4 at the enhancer loci of miR146a-5p gene during infection. Altogether, our findings revealed a novel role of BRD4/p300-depdendent super-enhancer in regulating miR146a expression during L. donovani infection which in turn mediates M2 polarization and immune-suppression.

Visceral leishmaniasis (VL), caused by protozoan parasites Leishmania donovani, is the most severe form of leishmaniasis and is highly lethal if left untreated. Major obstacle for successful therapy of VL originates from the life-long immune-suppression triggered in the post kala-azar dermal leishmaniasis (PKDL) patients during infection. Identification of molecular principles behind such immune-suppression will add success in VL therapeutics. L. donovani hijacks the host macrophages and converts them from pro-inflammatory M1 to immune-suppressive M2 type, which allows successful infection establishment. Herein, we explored the indispensable role of miRNA-146a-5p in conversion of M1 to M2 type during infection. Both in vitro and in vivo miRNA silencing established miR146a-5p as an imperative negative regulator ofM1 polarization. Computational analysis as well as immune precipitation based experiments authenticated that L. donovani induces super enhancer complex mediated transcriptional upregulation of miR146a-5p. BET bromodomain protein 4 (BRD4) forms this SE complex along with p300 histone acetyl transferase and RNA pol II. Silencing of BRD4 significantly abrogated miR146a-5p mediated M2 polarization. In short, our current findings established a previously unrecognized role of BRD4-depdendent super enhancers in orchestrating persistent transcription of macrophage miR146a-5p which in turn promotes M2 polarization during L. donovani infection.

Macrophages as host, effector and immunoregulatory cells in leishmaniasis: Impact of tissue micro-environment and metabolism

Leishmania are protozoan parasites that predominantly reside in myeloid cells within their mammalian hosts. Monocytes and macrophages play a central role in the pathogenesis of all forms of leishmaniasis, including cutaneous and visceral leishmaniasis. The present review will highlight the diverse roles of macrophages in leishmaniasis as initial replicative niche, antimicrobial effectors, immunoregulators and as safe hideaway for parasites persisting after clinical cure. These multiplex activities are either ascribed to defined subpopulations of macrophages (e.g., Ly6C^highCCR2⁺ inflammatory monocytes/monocyte-derived dendritic cells) or result from different activation statuses of tissue macrophages (e.g., macrophages carrying markers of of classical [M1] or alternative activation [M2]). The latter are shaped by immune- and stromal cell-derived cytokines (e.g., IFN-γ, IL-4, IL-10, TGF-β), micro milieu factors (e.g., hypoxia, tonicity, amino acid availability), host cell-derived enzymes, secretory products and metabolites (e.g., heme oxygenase-1, arginase 1, indoleamine 2,3-dioxygenase, NOS2/NO, NOX2/ROS, lipids) as well as by parasite products (e.g., leishmanolysin/gp63, lipophosphoglycan). Exciting avenues of current research address the transcriptional, epigenetic and translational reprogramming of macrophages in a Leishmania species- and tissue context-dependent manner.

Role of host genetics and cytokines in Leishmania infection

Cytokines and chemokines are important regulators of innate and specific responses in leishmaniasis, a disease that currently affects 12 million people. We overviewed the current information about influences of genetically engineered mouse models of cytokine and chemokine on leishmaniasis. We found that genetic background of the host, parasite species and sub-strain, as well as experimental design often modify effects of genetically engineered cytokine genes. Next we analyzed genes and QTLs (quantitative trait loci) that control response to Leishmania species in mouse in order to establish relationship between genetic control of cytokine expression and organ pathology. These studies revealed a network-like complexity of the combined effects of the multiple functionally diverse QTLs and their individual specificity. Genetic control of organ pathology and systemic immune response overlap only partially. Some QTLs control both organ pathology and systemic immune response, but the effects of genes and loci with the strongest impact on disease are cytokine-independent, whereas several loci modify cytokines levels in serum without influencing organ pathology. Understanding this genetic control might be important in development of vaccines designed to stimulate certain cytokine spectrum.