Nuclear receptor Nr1d1 alleviates asthma by abating GATA3 gene expression and Th2 cell differentiation.

Nuclear receptors are a unique family of transcription factors that play cardinal roles in physiology and plethora of human diseases. The adopted orphan nuclear receptor Nr1d1 is a constitutive transcriptional repressor known to modulate several biological processes. In this study, we found that Nr1d1 plays a decisive role in T helper (Th)-cell polarization and transcriptionally impedes the formation of Th2 cells by directly binding to the promoter region of GATA binding protein 3 (GATA3) gene. Nr1d1 interacts with its cellular companion, the nuclear receptor corepressor and histone deacetylase 3 to form a stable repression complex on the GATA3 promoter. The presence of Nr1d1 also imparts protection against associated inflammatory responses in murine model of asthma and its ligand SR9011 eased disease severity by suppressing Th2 responses. Moreover, Chip-seq profiling uncovered Nr1d1 interactions with other gene subsets that impedes Th2-linked pathways and regulates metabolism, immunity and brain functions, therefore, providing empirical evidence regarding the genetic link between asthma and other comorbid conditions. Thus, Nr1d1 emerges as a molecular switch that could be targeted to subdue asthma.

A human xenobiotic nuclear receptor contributes to nonresponsiveness of Mycobacterium tuberculosis to the antituberculosis drug rifampicin.

Mycobacterium tuberculosis is the causative agent of tuberculosis (TB). It acquires phenotypic drug resistance inside macrophages, and this resistance mainly arises from host-induced stress. However, whether cellular drug-efflux mechanisms in macrophages contribute to nonresponsiveness of M. tuberculosis to anti-TB drugs is unclear. Here, we report that xenobiotic nuclear receptors mediate TB drug nonresponsiveness by modulating drug-efflux transporters in macrophages. This was evident from expression analysis of drug-efflux transporters in macrophages isolated from TB patients. Among patients harboring rifampicin-susceptible M. tuberculosis, we observed increased intracellular survival of M. tuberculosis upon rifampicin treatment of macrophages isolated from patients not responding to anti-TB drugs compared with macrophages from patients who did respond. Of note, M. tuberculosis infection and rifampicin exposure synergistically modulated macrophage drug-efflux transporters in vitro We also found that the xenobiotic nuclear receptor pregnane X receptor (PXR) modulates macrophage drug-efflux transporter expression and activity, which compromised the anti-TB efficacy of rifampicin. We further validated this finding in a TB mouse model in which use of the PXR antagonist ketoconazole rescued rifampicin anti-TB activity. We conclude that PXR activation in macrophages compromises the efficacy of the anti-TB drug rifampicin. Alternative therapeutic strategies, such as use of the rifampicin derivatives rifapentine and rifabutin, which do not activate PXR, or of a PXR antagonist, may be effective for tackling drug nonresponsiveness of M. tuberculosis that arises from drug-efflux systems of the host.

Human Xenobiotic Nuclear Receptor PXR Augments Mycobacterium tuberculosis Survival.

Mycobacterium tuberculosis can evade host defense processes, thereby ensuring its survival and pathogenesis. In this study, we investigated the role of nuclear receptor, pregnane X receptor (PXR), in M. tuberculosis infection in human monocyte-derived macrophages. In this study, we demonstrate that PXR augments M. tuberculosis survival inside the host macrophages by promoting the foamy macrophage formation and abrogating phagolysosomal fusion, inflammation, and apoptosis. Additionally, M. tuberculosis cell wall lipids, particularly mycolic acids, crosstalk with human PXR (hPXR) by interacting with its promiscuous ligand binding domain. To confirm our in vitro findings and to avoid the reported species barrier in PXR function, we adopted an in vivo mouse model expressing hPXR, wherein expression of hPXR in mice promotes M. tuberculosis survival. Therefore, pharmacological intervention and designing antagonists to hPXR may prove to be a promising adjunct therapy for tuberculosis.

The Active Form of Vitamin D Transcriptionally Represses Smad7 Signaling and Activates Extracellular Signal-regulated Kinase (ERK) to Inhibit the Differentiation of a Inflammatory T Helper Cell Subset and Suppress Experimental Autoimmune Encephalomyelitis.

The ability of the active form of vitamin D, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), to transcriptionally modulate Smads to inhibit Th17 differentiation and experimental autoimmune encephalomyelitis (EAE) has not been adequately studied. This study reports modulation of Smad signaling by the specific binding of the VDR along with its heterodimeric partner RXR to the negative vitamin D response element on the promoter of Smad7, which leads to Smad7 gene repression. The vitamin D receptor-mediated increase in Smad3 expression partially explains the IL10 augmentation seen in Th17 cells. Furthermore, the VDR axis also modulates non-Smad signaling by activating ERK during differentiation of Th17 cells, which inhibits the Th17-specific genes il17a, il17f, il22, and il23r. In vivo EAE experiments revealed that, 1,25(OH)2D3 suppression of EAE correlates with the Smad7 expression in the spleen and lymph nodes. Furthermore, Smad7 expression also correlates well with IL17 and IFNγ expression in CNS infiltered inflammatory T cells. We also observed similar gene repression of Smad7 in in vitro differentiated Th1 cells when cultured in presence of 1,25(OH)2D3. The above canonical and non-canonical pathways in part address the ability of 1,25(OH)2D3-VDR to inhibit EAE.

Nuclear Receptor Nr4a2 Promotes Alternative Polarization of Macrophages and Confers Protection in Sepsis.

The orphan nuclear receptor Nr4a2 is known to modulate both inflammatory and metabolic processes, but the mechanism by which it regulates innate inflammatory homeostasis has not been adequately addressed. This study shows that exposure to ligands for Toll-like receptors (TLRs) robustly induces Nr4a2 and that this induction is tightly regulated by the PI3K-Akt signaling axis. Interestingly, exogenous expression of Nr4a2 in macrophages leads to their alternative phenotype with induction of genes that are prototypical M2 markers. Moreover, Nr4a2 transcriptionally activates arginase 1 expression by directly binding to its promoter. Adoptive transfer experiments revealed that increased survival of animals in endotoxin-induced sepsis is Nr4a2-dependent. Thus our data identify a previously unknown role for Nr4a2 in the regulation of macrophage polarization.

Discovery of Mycobacterium tuberculosis α-1,4-glucan branching enzyme (GlgB) inhibitors by structure- and ligand-based virtual screening.

GlgB (α-1,4-glucan branching enzyme) is the key enzyme involved in the biosynthesis of α-glucan, which plays a significant role in the virulence and pathogenesis of Mycobacterium tuberculosis. Because α-glucans are implicated in the survival of both replicating and non-replicating bacteria, there exists an exigent need for the identification and development of novel inhibitors for targeting enzymes, such as GlgB, involved in this pathway. We have used the existing structural information of M. tuberculosis GlgB for high throughput virtual screening and molecular docking. A diverse database of 330,000 molecules was used for identifying novel and efficacious therapeutic agents for targeting GlgB. We also used three-dimensional shape as well as two-dimensional similarity matrix methods to identify diverse molecular scaffolds that inhibit M. tuberculosis GlgB activity. Virtual hits were generated after structure and ligand-based screening followed by filters based on interaction with human GlgB and in silico pharmacokinetic parameters. These hits were experimentally evaluated and resulted in the discovery of a number of structurally diverse chemical scaffolds that target M. tuberculosis GlgB. Although a number of inhibitors demonstrated in vitro enzyme inhibition, two compounds in particular showed excellent inhibition of in vivo M. tuberculosis survival and its ability to get phagocytosed. This work shows that in silico docking and three-dimensional chemical similarity could be an important therapeutic approach for developing inhibitors to specifically target the M. tuberculosis GlgB enzyme.

Parenteral Vaccination with a Live Brucella melitensis Mutant Protects against Wild-Type B. melitensis 16M Challenge.

Susceptibility to brucellosis remains prevalent, even in herds vaccinated with conventional vaccines. Efforts are underway to develop an improved brucellosis vaccine, and possibly a universal vaccine, given that Brucella species are highly homologous. To this end, two B. melitensis mutants were developed, znBM-lacZ (znBMZ) and znBM-mCherry (znBM-mC), and were tested for their ability to confer systemic immunity against virulent B. melitensis challenge. To assess the extent of their attenuation, bone-marrow-derived macrophages and human TF-1 myeloid cells were infected with both mutants, and the inability to replicate within these cells was noted. Mice infected with varying doses of znBM-mC cleared the brucellae within 6-10 weeks. To test for efficacy against systemic disease, groups of mice were vaccinated once by the intraperitoneal route with either znBMZ or B. abortus S19 vaccine. Relative to the PBS-dosed mice, znBMZ vaccination greatly reduced splenic brucellae colonization by ~25,000-fold compared to 700-fold for S19-vaccinated mice. Not surprisingly, both znBMZ and S19 strains induced IFN-γ+ CD4+ T cells, yet only znBMZ induced IFN-γ+ CD8+ T cells. While both strains induced CD4+ effector memory T cells (Tems), only znBMZ induced CD8+ Tems. Thus, these results show that the described znBM mutants are safe, able to elicit CD4+ and CD8+ T cell immunity without a boost, and highly effective, rendering them promising vaccine candidates for livestock.

Nr1h4 and Thrb ameliorate ER stress and provide protection in the MPTP mouse model of Parkinson's.

Elevated ER stress has been linked to the pathogenesis of several disease conditions including neurodegeneration. In this study, we have holistically determined the differential expression of all the nuclear receptors (NRs) in the presence of classical ER stress inducers. Activation of Nr1h4 and Thrb by their cognate ligands (GW4064 and T3) ameliorates the tunicamycin (TM)-induced expression of ER stress genes. A combination of both ligands is effective in mitigating cell death induced by TM. Further exploration of their protective effects in the Parkinson's disease (PD) model shows that they reduce MPP+-induced dissipation of mitochondrial membrane potential and ROS generation in an in vitro PD model in neuronal cells. Furthermore, the generation of an experimental murine PD model reveals that simultaneous treatment of GW4064 and T3 protects mice from ER stress, dopaminergic cell death, and functional deficits in the MPTP mouse model of PD. Thus, activation of Nr1h4 and Thrb by their respective ligands plays an indispensable role in ER stress amelioration and mounts protective effects in the MPTP mouse model of PD.

Nuclear receptor Rev-erbα role in fine-tuning erythropoietin gene expression.

ABSTRACT: The regulation of red blood cell (RBC) homeostasis by erythropoietin (EPO) is critical for O2 transport and maintaining the adequate number of RBCs in vertebrates. Therefore, dysregulation in EPO synthesis results in disease conditions such as polycythemia in the case of excessive EPO production and anemia, which occurs when EPO is inadequately produced. EPO plays a crucial role in treating anemic patients; however, its overproduction can increase blood viscosity, potentially leading to fatal heart failure. Consequently, the identification of druggable transcription factors and their associated ligands capable of regulating EPO offers a promising therapeutic approach to address EPO-related disorders. This study unveils a novel regulatory mechanism involving 2 pivotal nuclear receptors (NRs), Rev-ERBA (Rev-erbα, is a truncation of reverse c-erbAa) and RAR-related orphan receptor A (RORα), in the control of EPO gene expression. Rev-erbα acts as a cell-intrinsic negative regulator, playing a vital role in maintaining erythropoiesis at the correct level. It accomplishes this by directly binding to newly identified response elements within the human and mouse EPO gene promoter, thereby repressing EPO production. These findings are further supported by the discovery that a Rev-erbα agonist (SR9011) effectively suppresses hypoxia-induced EPO expression in mice. In contrast, RORα functions as a positive regulator of EPO gene expression, also binding to the same response elements in the promoter to induce EPO production. Finally, the results of this study revealed that the 2 NRs, Rev-erbα and RORα, influence EPO synthesis in a negative and positive manner, respectively, suggesting that the modulating activity of these 2 NRs could provide a method to target disorders linked with EPO dysregulation.

Host factors subverted by Mycobacterium tuberculosis: Potential targets for host directed therapy.

INTRODUCTION: Despite new approaches in the diagnosis and treatment of tuberculosis (TB), it continues to be a major health burden. Several immunotherapies that potentiate the immune response have come up as adjuncts to drug therapies against drug resistant TB strains; however, there needs to be an urgent appraisal of host specific drug targets for improving their clinical management and to curtail disease progression. Presently, various host directed therapies (HDTs) exist (repurposed drugs, nutraceuticals, monoclonal antibodies and immunomodulatory agents), but these mostly address molecules that combat disease progression. AREAS COVERED: The current review discusses major Mycobacterium tuberculosis (M. tuberculosis) survival paradigms inside the host and presents a plethora of host targets subverted by M. tuberculosis which can be further explored for future HDTs. The host factors unique to M. tuberculosis infection (in humans) have also been identified through an in-silico interaction mapping. EXPERT OPINION: HDTs could become the next-generation adjunct therapies in order to counter antimicrobial resistance and virulence, as well as to reduce the duration of existing TB treatments. However, current scientific efforts are largely directed toward combatants rather than host molecules co-opted by M. tuberculosis for its survival. This might drive the immune system to a hyper-inflammatory condition; therefore, we emphasize that host factors subverted by M. tuberculosis, and their subsequent neutralization, must be considered for development of better HDTs.

Activation of mucosal immunity as a novel therapeutic strategy for combating brucellosis.

Brucellosis is a disease of livestock that is commonly asymptomatic until an abortion occurs. Disease in humans results from contact of infected livestock or consumption of contaminated milk or meat. Brucella zoonosis is primarily caused by one of three species that infect livestock, Bacillus abortus in cattle, B. melitensis in goats and sheep, and B. suis in pigs. To aid in disease prophylaxis, livestock vaccines are available, but are only 70% effective; hence, improved vaccines are needed to mitigate disease, particularly in countries where disease remains pervasive. The absence of knowing which proteins confer complete protection limits development of subunit vaccines. Instead, efforts are focused on developing new and improved live, attenuated Brucella vaccines, since these mimic attributes of wild-type Brucella, and stimulate host immune, particularly T helper 1-type responses, required for protection. In considering their development, the new mutants must address Brucella's defense mechanisms normally active to circumvent host immune detection. Vaccination approaches should also consider mode and route of delivery since disease transmission among livestock and humans is believed to occur via the naso-oropharyngeal tissues. By arming the host's mucosal immune defenses with resident memory T cells (TRMs) and by expanding the sources of IFN-γ, brucellae dissemination from the site of infection to systemic tissues can be prevented. In this review, points of discussion focus on understanding the various immune mechanisms involved in disease progression and which immune players are important in fighting disease.

Oral probiotic promotes indoleamine 2,3-dioxygenase- and TGF-ß-Producing plasmacytoid dendritic cells to initiate protection against type 1 diabetes.

Colonization factor antigen I (CFA/I) fimbria, an adhesin from enterotoxigenic Escherichia coli, confers protection in murine autoimmune models for type 1 diabetes (T1D), multiple sclerosis, and rheumatoid arthritis. Although CFA/I fimbriae's initial mode of action is in a bystander or in an antigen (Ag)-independent fashion, protection is ultimately dependent upon the induction and/or activation of auto-Ag-specific regulatory T cells (Tregs). However, little is known about how protection transitions from bystander suppression to Ag-specific Tregs. Since dendritic cells (DCs) play an integral role in fate decisions for T cells becoming inflammatory or tolerogenic, the described study tests the hypothesis that Lactococcus lactis expressing CFA/I (LL-CFA/I) stimulates DCs to establish a regulatory microenvironment. To this end, bone marrow-derived dendritic cells (BMDCs) were infected in vitro with LL-CFA/I. Results revealed increased production of IL-10, TGF-ß, and indoleamine 2,3-deoxygenase (IDO). Although co-culture of LL-CFA/I infected BMDCs with naïve T cells did not promote Foxp3 expression, TNF-α and IFN-γ production was suppressed. NOD mice orally dosed with LL-CFA/I showed an increase in regulatory plasmacytoid DCs (pDCs) expressing IDO and TGF-ß in pancreatic lymph nodes (PaLNs) and spleen three days post-treatment. However, Tregs did not appear in the mucosal inductive sites until much later. These findings show that LL-CFA/I influences specific DC populations to establish tolerance.

Mucosal Vaccination Primes NK Cell-Dependent Development of CD8+ T Cells Against Pulmonary Brucella Infection.

Past studies with the live, double-mutant B. abortus (znBAZ) strain resulted in nearly complete protection of mice against pulmonary challenge with wild-type (wt) Brucella via a dominant CD8+ T cell response. To understand the contribution innate immune cells in priming CD8+ T cell responses, mice were nasally dosed with wt B. abortus, smooth vaccine strain 19 (S19), or znBAZ, and examined for innate immune cell activation. Flow cytometric analysis revealed that znBAZ, but not wt B. abortus nor S19 infection, induces up to a 5-fold increase in the frequency of IFN-γ-producing NK cells in mouse lungs. These NK cells express increased CXCR3 and Ki67, indicating their recruitment and proliferation subsequent to znBAZ infection. Their activation status was augmented noted by the increased NKp46 and granzyme B, but decreased NKG2A expression. Further analysis demonstrated that both lung caspase-1+ inflammatory monocytes and monocyte-derived macrophages secrete chemokines and cytokines responsible for NK cell recruitment and activation. Moreover, neutralizing IL-18, an NK cell-activating cytokine, reduced the znBAZ-induced early NK cell response. NK cell depletion also significantly impaired lung dendritic cell (DC) activation and migration to the lower respiratory lymph nodes (LRLNs). Both lung DC activation and migration to LRLNs were significantly impaired in NK cell-depleted or IFN-γ-/- mice, particularly the CD11b+ and monocytic DC subsets. Furthermore, znBAZ vaccination significantly induced CD8+ T cells, and upon in vivo NK cell depletion, CD8+ T cells were reduced 3-fold compared to isotype-treated mice. In summary, these data show that znBAZ induces lung IFN-γ+ NK cells, which plays a critical role in influencing lung DC activation, migration, and promoting protective CD8+ T cell development.

Vitamin D3-VDR-PTPN6 axis mediated autophagy contributes to the inhibition of macrophage foam cell formation.

Macrophage derived foam cells in atherosclerotic plaques are the major factor responsible for the pathogenesis of atherosclerosis (AS). During advanced AS, macrophage-specific macroautophagy/autophagy is dysfunctional. 1, 25-dihydroxy vitamin D3 (VitD3) and its receptor VDR (vitamin D receptor) are reported to inhibit foam cell formation and induce autophagy; however, the role of VitD3-VDR-induced autophagy and foam cell formation in AS has not been explored. Here we find that VitD3 significantly recovered oxidized low-density lipoprotein-impaired autophagy, as well as increased autophagy-mediated lipid breakdown in mouse bone marrow-derived macrophages and human monocyte-derived macrophages, thus inhibiting the conversion of macrophages into foam cells. Importantly, VitD3 functions through its receptor VDR to upregulate autophagy and attenuate the accumulation of lipids in macrophages. Moreover, this study is the first occasion to report the interesting link between VitD3 signaling and PTPN6/SHP-1 (protein tyrosine phosphatase non-receptor type 6) in macrophages. VitD3-induced autophagy was abrogated in the presence of the PTPN6/Ptpn6 shRNA or inhibitor. VDR along with RXRA (retinoid X receptor alpha), and NCOA1 (nuclear receptor coactivator 1), are recruited to a specific response element located on the gene promoter and induce PTPN6 expression. PTPN6 contributes to VitD3-mediated autophagy by regulating autophagy-related genes via activation of MAPK1 (mitogen-activated protein kinase 1) and CEBPB (CCAAT enhancer binding protein beta). Furthermore, expression of PTPN6 is also crucial for VitD3-mediated inhibition of macrophage foam cell formation through autophagy. Thus, VitD3-VDR-PTPN6 axis-regulated autophagy attenuates foam cell formation in macrophages.

Stimulation of regulatory T cells with Lactococcus lactis expressing enterotoxigenic E. coli colonization factor antigen 1 retains salivary flow in a genetic model of Sjögren's syndrome.

BACKGROUND: Sjögren's syndrome (SjS), one of the most common autoimmune diseases, impacts millions of people annually. SjS results from autoimmune attack on exocrine (salivary and lacrimal) glands, and women are nine times more likely to be affected than men. To date, no vaccine or therapeutic exists to treat SjS, and patients must rely on lifelong therapies to alleviate symptoms. METHODS: Oral treatment with the adhesin from enterotoxigenic Escherichia coli colonization factor antigen I (CFA/I) fimbriae protects against several autoimmune diseases in an antigen (Ag)-independent manner. Lactococcus lactis, which was recently adapted to express CFA/I fimbriae (LL-CFA/I), effectively suppresses inflammation by the induction of infectious tolerance via Ag-specific regulatory T cells (Tregs), that produce IL-10 and TGF-ß. To test the hypothesis that CFA/I fimbriae can offset the development of inflammatory T cells via Treg induction, oral treatments with LL-CFA/I were performed on the spontaneous, genetically defined model for SjS, C57BL/6.NOD-Aec1Aec2 mice to maintain salivary flow. RESULTS: Six-week (wk)-old C57BL/6.NOD-Aec1Aec2 mice were orally dosed with LL-CFA/I and treated every 3 wks; control groups were given L. lactis vector or PBS. LL-CFA/I-treated mice retained salivary flow up to 28 wks of age and showed significantly reduced incidence of inflammatory infiltration into the submandibular and lacrimal glands relative to PBS-treated mice. A significant increase in Foxp3+ and IL-10- and TGF-ß-producing Tregs was observed. Moreover, LL-CFA/I significantly reduced the expression of proinflammatory cytokines, IL-6, IL-17, GM-CSF, and IFN-γ. Adoptive transfer of CD4+ T cells from LL-CFA/I-treated, not LL vector-treated mice, restored salivary flow in diseased SjS mice. CONCLUSION: These data demonstrate that oral LL-CFA/I reduce or halts SjS progression, and these studies will provide the basis for future testing in SjS patients.

TGF-ß induced chemoresistance in liver cancer is modulated by xenobiotic nuclear receptor PXR.

Hepatocellular carcinoma appears as an extremely angiogenic solid tumor marked by apoptosis evasion, dysregulated cell cycle and low sensitivity to chemotherapy. TGF-ß, a multifunctional cytokine, plays a pleiotropic role in the tumor microenvironment and has implications in cancer drug resistance. The current study provides novel evidence that TGF-ß signaling contributes to drug resistance in liver cancer cells by inducing the expression of xenobiotic nuclear receptor PXR. We observed that PXR increases the expression of drug efflux transporters; therefore, accounting for exacerbated drug resistance. Additionally, anti-apoptotic nature of PXR contributes to TGF-ß mediated chemoresistance as seen by procaspase-3 and Mcl-1 cellular levels. TGF-ß binding to the TGF-ß receptor triggers a complex downstream signaling cascade through a non-canonical SMAD-independent ERK pathway that leads to increased PXR expression. Activated ERK activates ETS1 transcription factor which is a critical regulator of endogenous PXR expression in hepatic cells. Loss of function of ETS1 abrogates the TGF-ß induced PXR expression. Together these findings indicate that PXR modulates TGF-ß induced resistance to chemotherapy in liver cancer cells. This underscores the need for combinatorial approaches with focus on PXR antagonism to improve drug effectiveness in hepatocellular carcinoma.Abbreviations: HCC: Hepatocellular Carcinoma; FDA: Food and Drug Administration; TGF-ß: Transforming growth factor-ß; PXR: Pregnane X receptor; CAR: Constitutive androstane receptor; P-gp/ABCB1: P-glycoproteins/ATP-binding cassette transporter subfamily B member 1; MRP1/ABCC1 and MRP2/ABCC2: Multidrug-resistance associated proteins; BCRP/ABCG2: Breast cancer resistant protein; DMEs: Drug-metabolizing enzymes; CFDA: 5,6-carboxyfluorescein diacetate; ETS1: Transcription factor E26 transformation specific sequence 1.

An Accord of Nuclear Receptor Expression in CD4+ T Cells in Rheumatoid Arthritis.

Chronically activated CD4+ T cells drive uncontrolled inflammation, leading to tissue damage in various autoimmune disorders, such as rheumatoid arthritis (RA). Investigation of the molecular mechanisms involved in RA and recent analysis of transcriptomic profiles has implicated members of the nuclear receptor (NR) superfamily in RA. NRs are required for the development, differentiation, and effector function of CD4+ T cells; therefore, it is thought that NRs are important in shaping the CD4+ T cell repertoire and associated inflammation in RA. Despite their relevance, the full potential of the NR superfamily in RA, either as biomarkers or disease targets, has not been harnessed. To gain insight on the NR members that are closely associated with RA disease activity, we generated an expression atlas for the NR superfamily in CD4+ T cells isolated either in a steady state or over the course of collagen-induced arthritis mouse model of RA. We observed discrete expression patterns among the NR superfamily during the disease stages. NRs that instigate anti-inflammatory programs underwent major downregulation during disease onset; however, during the fully developed disease stage we noticed that NRs that induce proinflammatory programs had reduced transcript levels. These animal findings corroborated well with the expression patterns of NRs in clinical samples obtained from RA patients. Furthermore, we observed that targeting NRs using synthetic ligands alleviates the progression of collagen-induced arthritis. Overall, our data demonstrates the potential of the NR superfamily as novel therapeutic targets for the treatment of autoimmune disorders.

AutophagySMDB: a curated database of small molecules that modulate protein targets regulating autophagy.

Macroautophagy/autophagy is a complex self-degradative mechanism responsible for clearance of non functional organelles and proteins. A range of factors influences the autophagic process, and disruptions in autophagy-related mechanisms lead to disease states, and further exacerbation of disease. Despite in-depth research into autophagy and its role in pathophysiological processes, the resources available to use it for therapeutic purposes are currently lacking. Herein we report the Autophagy Small Molecule Database (AutophagySMDB; http://www.autophagysmdb.org/ ) of small molecules and their cognate protein targets that modulate autophagy. Presently, AutophagySMDB enlists ~10,000 small molecules which regulate 71 target proteins. All entries are comprised of information such as EC50 (half maximal effective concentration), IC50 (half maximal inhibitory concentration), Kd (dissociation constant) and Ki (inhibition constant), IUPAC name, canonical SMILE, structure, molecular weight, QSAR (quantitative structure activity relationship) properties such as hydrogen donor and acceptor count, aromatic rings and XlogP. AutophagySMDB is an exhaustive, cross-platform, manually curated database, where either the cognate targets for small molecule or small molecules for a target can be searched. This database is provided with different search options including text search, advanced search and structure search. Various computational tools such as tree tool, cataloging tools, and clustering tools have also been implemented for advanced analysis. Data and the tools provided in this database helps to identify common or unique scaffolds for designing novel drugs or to improve the existing ones for autophagy small molecule therapeutics. The approach to multitarget drug discovery by identifying common scaffolds has been illustrated with experimental validation. Abbreviations: AMPK: AMP-activated protein kinase; ATG: autophagy related; AutophagySMDB: autophagy small molecule database; BCL2: BCL2, apoptosis regulator; BECN1: beclin 1; CAPN: calpain; MTOR: mechanistic target of rapamycin kinase; PPARG: peroxisome proliferator activated receptor gamma; SMILES: simplified molecular input line entry system; SQSTM1: sequestosome 1; STAT3: signal transducer and activator of transcription.

An Accord of Nuclear Receptor Expression in M. tuberculosis Infected Macrophages and Dendritic Cells.

Mycobacterium tuberculosis instigates interactions with host factors to promote its survival within the host inimical conditions. Among such factors, nuclear receptors (NRs) seem to be promising candidates owing to their role in bacterial pathogenesis. However, only few members of NR superfamily have been implicated in M. tuberculosis infection and there is a dearth of comprehensive knowledge about expression or function of the entire superfamily. In this study, we performed detailed expression analysis and identified key NRs getting differentially regulated in murine macrophages and dendritic cells (DC) upon infection with H37Rv. The murine macrophages and DCs infected with H37Rv entailed overlapping changes in the expression of certain NRs which reflect upon the possibility that both cells might utilize similar transcriptional programs upon M. tuberculosis infection. We identified Nr4a3 and Rora, which have not been implicated in M. tuberculosis pathogenesis, undergo similar changes in expression in macrophages and DCs upon H37Rv infection. Interestingly, a similar pattern in their expression was also observed in infected human monocyte derived macrophages and the findings corroborated well with PBMCs obtained from TB patients. This all-inclusive analysis provides the basis for a precise approach in identifying NRs that can be targeted therapeutically in intracellular bacterial infections.

AIRE promotes androgen-independent prostate cancer by directly regulating IL-6 and modulating tumor microenvironment.

Early stage prostate cancers are dependent on androgens for their growth and survival and androgen withdrawal causes them to regress. Progressive prostate cancers eventually acquire androgen independence rendering anti-androgen therapy ineffective. However, the factors leading to this have not been adequately addressed. This study shows that AIRE finds differential expression in androgen-dependent and -independent prostate cancer cells. AIRE expression is more in androgen-independent cells due to its regulation by transcription factor Elk-1. These enhanced levels of AIRE modulate the prostate tumor microenvironment by transcriptionally activating a malignancy gene IL-6 in androgen-independent cells. Additionally, AIRE prevents the cancer cells from anticancer drug-induced death and enhances their invasiveness. Moreover, AIRE by modulating the cytokine milieu skews the tumor-associated macrophage polarization towards M2 phenotype with increased CD206 and CD163 expression. Subcutaneous mouse model of prostate cancer revealed AIRE+/+ mice forming a palpable tumor and presents lymphadenopathy however, only a small benign tumor is observed in AIRE-/- mice and lymph nodes appear normal in size. In conclusion, our findings suggest AIRE as a probable factor in promoting prostate cancer progression.