Phase II trial of single-agent panobinostat consolidation improves responses after sub-optimal transplant outcomes in multiple myeloma.

Panobinostat is a pan-deacetylase inhibitor that modulates the expression of oncogenic and immune-mediating genes involved in tumour cell growth and survival. We evaluated panobinostat-induced post-transplant responses and identified correlative biomarkers in patients with multiple myeloma who had failed to achieve a complete response after autologous transplantation. Patients received panobinostat 45 mg administered three-times weekly (TIW) on alternate weeks of 28-day cycles commencing 8-12 weeks post-transplant. Twelve of 25 patients (48%) improved their depth of response after a median (range) of 4·3 (1·9-9·7) months of panobinostat. In responders, T-lymphocyte histone acetylation increased after both three cycles (P < 0·05) and six cycles (P < 0·01) of panobinostat when compared to baseline, with no differences in non-responders. The reduction in the proportion of CD127+ CD8+ T cells and CD4:CD8 ratio was significantly greater, after three and six cycles of panobinostat compared to pre-transplant, in non-responders when compared to responders. Whole marrow RNA-seq revealed widespread transcriptional changes only in responders with baseline differences in genes involved in ribosome biogenesis, oxidative phosphorylation and metabolic pathways. This study confirmed the efficacy of panobinostat as a single agent in multiple myeloma and established acetylation of lymphocyte histones, modulation of immune subsets and transcriptional changes as pharmacodynamic biomarkers of clinical benefit.

Long-Acting BMS-378806 Analogues Stabilize the State-1 Conformation of the Human Immunodeficiency Virus Type 1 Envelope Glycoproteins.

During human immunodeficiency virus type 1 (HIV-1) entry into cells, the viral envelope glycoprotein (Env) trimer [(gp120/gp41)3] binds the receptors CD4 and CCR5 and fuses the viral and cell membranes. CD4 binding changes Env from a pretriggered (state-1) conformation to more open downstream conformations. BMS-378806 (here called BMS-806) blocks CD4-induced conformational changes in Env important for entry and is hypothesized to stabilize a state-1-like Env conformation, a key vaccine target. Here, we evaluated the effects of BMS-806 on the conformation of Env on the surface of cells and virus-like particles. BMS-806 strengthened the labile, noncovalent interaction of gp120 with the Env trimer, enhanced or maintained the binding of most broadly neutralizing antibodies, and decreased the binding of poorly neutralizing antibodies. Thus, in the presence of BMS-806, the cleaved Env on the surface of cells and virus-like particles exhibits an antigenic profile consistent with a state-1 conformation. We designed novel BMS-806 analogues that stabilized the Env conformation for several weeks after a single application. These long-acting BMS-806 analogues may facilitate enrichment of the metastable state-1 Env conformation for structural characterization and presentation to the immune system.IMPORTANCE The envelope glycoprotein (Env) spike on the surface of human immunodeficiency virus type 1 (HIV-1) mediates the entry of the virus into host cells and is also the target for antibodies. During virus entry, Env needs to change shape. Env flexibility also contributes to the ability of HIV-1 to evade the host immune response; many shapes of Env raise antibodies that cannot recognize the functional Env and therefore do not block virus infection. We found that an HIV-1 entry inhibitor, BMS-806, stabilizes the functional shape of Env. We developed new variants of BMS-806 that stabilize Env in its natural state for long periods of time. The availability of such long-acting stabilizers of Env shape will allow the natural Env conformation to be characterized and tested for efficacy as a vaccine.

Association of synovial tissue polyfunctional T-cells with DAPSA in psoriatic arthritis.

OBJECTIVE: This study examines polyfunctional T-cells in psoriatic arthritis (PsA) synovial tissue and their associations with clinical disease and implications for therapy. METHODS: PsA synovial tissue was enzymatically/mechanically digested to generate synovial tissue single cell suspensions. Frequencies of polyfunctional CD4, CD8, T-helper 1 (Th1), Th17 and exTh17 cells, using CD161 as a marker of Th17 plasticity, were determined by flow cytometry in matched PsA synovial tissue and peripheral blood. Synovial T-cell polyfunctionality was assessed in relation to Disease Activity in PSoriatic Arthritis (DAPSA) and in synovial cell suspensions cultured with a current mode of treatment, phosphodiesterase 4 (PDE4) inhibitor. RESULTS: PsA synovial tissue infiltrating CD4+ T-cells expressed higher levels of interleukin (IL)-17A, interferon gamma (IFN-γ), GM-CSF and CD161, with parallel enrichment of Th1, Th17 and exTh17 T-helper subsets (all p<0.05). Interestingly, a significant proportion of synovial T-cell subsets were triple-positive for GM-CSF, tumour necrosis factor (-TNF), -IL-17 or IFN-γ compared with matched blood (all p<0.05). Importantly, frequencies of polyfunctional T-cells correlated with DAPSA: Th1-GM-CSF+/TNF+/IFN-γ+ (r=0.7, p<0.01), Th17-GM-CSF+/TNF+/IL-17+ (r=0.6, p<0.057) and exTh17-GM-CSF+/TNF+/IFN-γ+ (r=0.7, p=0.0096), with no associations observed for single cytokine-producing T-cells. Following ex vivo culture of PsA synovial tissue cell suspensions, polyfunctional GM-CSF+TNFα+IL-17A+ or/IFN-γ+-producing T-cells (p<0.05), but not single cytokine-producing T-cells, were inhibited with a PDE4 inhibitor. CONCLUSION: These data demonstrate enrichment of polyfunctional T-cells in PsA synovial tissue which were strongly associated with DAPSA and ex vivo therapeutic response.

TCR-peptide-MHC interactions in situ show accelerated kinetics and increased affinity.

The recognition of foreign antigens by T lymphocytes is essential to most adaptive immune responses. It is driven by specific T-cell antigen receptors (TCRs) binding to antigenic peptide-major histocompatibility complex (pMHC) molecules on other cells. If productive, these interactions promote the formation of an immunological synapse. Here we show that synaptic TCR-pMHC binding dynamics differ significantly from TCR-pMHC binding in solution. We used single-molecule microscopy and fluorescence resonance energy transfer (FRET) between fluorescently tagged TCRs and their cognate pMHC ligands to measure the kinetics of TCR-pMHC binding in situ. When compared with solution measurements, the dissociation of this complex was increased significantly (4-12-fold). Disruption of actin polymers reversed this effect, indicating that cytoskeletal dynamics destabilize this interaction directly or indirectly. Nevertheless, TCR affinity for pMHC was significantly elevated as the result of a large (about 100-fold) increase in the association rate, a likely consequence of complementary molecular orientation and clustering. In helper T cells, the CD4 molecule has been proposed to bind cooperatively with the TCR to the same pMHC complex. However, CD4 blockade had no effect on the synaptic TCR affinity, nor did it destabilize TCR-pMHC complexes, indicating that the TCR binds pMHC independently of CD4.

2-Aminothiazolones as anti-HIV agents that act as gp120-CD4 inhibitors.

We report here the synthesis of 2-aminothiazolones along with their biological properties as novel anti-HIV agents. Such compounds have proven to act through the inhibition of the gp120-CD4 protein-protein interaction that occurs at the very early stage of the HIV-1 entry process. No cytotoxicity was found for these compounds, and broad antiviral activities against laboratory strains and pseudotyped viruses were documented. Docking simulations have also been applied to predict the mechanism, at the molecular level, by which the inhibitors were able to interact within the Phe43 cavity of HIV-1 gp120. Furthermore, a preliminary absorption, distribution, metabolism, and excretion (ADME) evaluation was performed. Overall, this study led the basis for the development of more potent HIV entry inhibitors.

Frequency of amino acid changes associated with resistance to attachment inhibitor BMS-626529 in R5- and X4-tropic HIV-1 subtype B.

OBJECTIVES: Resistance to attachment inhibitor BMS-626529, which inhibits the binding of HIV to CD4, involves mutations in the HIV-1 gp120 gene. There is a lack of information on the primary resistance of HIV-1 subtype B to attachment inhibitors, so we decided to investigate. METHODS: Sequences from 109 attachment-inhibitor-naive patients infected with HIV-1 subtype B were analysed for the presence of previously described in vivo resistance mutations associated with attachment inhibitor BMS-626529 and tropism determination. RESULTS: The M426L substitution associated with a reduced efficacy of the attachment inhibitor BMS-626529 was present at 7.3%. There was no difference in mutation distribution according to virus tropism (R5 or X4). CONCLUSIONS: The attachment inhibitor BMS-626529 is suitable for most patients infected with HIV-1 subtype B.

The antioxidant MnTBAP does not effectively downregulate CD4 expression in T cells in vivo.

The antioxidant MnTBAP was previously shown to down-regulate the surface expression of CD4 molecule in T cells. This observation obviously holds great potential impact in a number of pathological human conditions, including autoimmunity. Three different single doses of MnTBAP reduced the frequency of CD4high cells. However, the median florescent intensity (MFI) was not different. Initiation of in vivo pharmacotherapy or vehicle control was performed inC57BL/6 mice that were actively immunized for experimental autoimmune encephalomyelitis (EAE). In contrast to published reports, the mean frequency of CD4high cells, and the median fluorescent intensity (MFI) of CD4 was similar in both treatment groups. 25-day survival following active immunization among the MnTBAP treated animals compared to vehicle controls was16.6 ± 6.9 days vs 23.6 ± 2.7 days; (P value <0.05). We conclude that MnTBAP (Sack and Herzog, 2009 (Sack and Herzog, 2009)) does not effectively downregulate CD4 expression in T cells in vivo, probably due to extensive mechanism that distinguishes it from an in vitro model (Harding, 1993 (Harding, 1993)) possesses toxic properties that may limit its clinic use in possible doses that could deliver the immunomodulation through down regulation of CD4 expression, and (Saizawa et al., 1987 (Saizawa et al., 1987)) has limited availability in specific tissues, including the CNS.

Phorbol ester-induced downregulation of CD4 is a multistep process involving dissociation from p56lck, increased association with clathrin-coated pits, and altered endosomal sorting.

The phorbol ester phorbol myristate acetate (PMA) induces a rapid downregulation of CD4 from the surface of T cells and lymphocytic cell lines, as well as from CD4-transfected nonlymphoid cells. Here we have studied the mechanisms of this phorbol ester-induced CD4 modulation. Using HeLa-CD4 or NIH-3T3-CD4 cells, in which the endocytosis of CD4 is not influenced by the protein tyrosine kinase p56lck, we show that PMA enhanced the uptake of CD4, increasing the rate of CD4 endocytosis three to five-fold, and doubling the proportion of CD4 found inside the cells. Trafficking of a CD4 mutant lacking the major portion of the cytoplasmic domain, as well as fluid phase endocytosis were not affected by PMA treatment. Studies in which clathrin-coated pits were disrupted through the use of hypertonic media indicated that both the constitutive and PMA-induced CD4 uptake occurred through coated vesicles. Electron microscopy demonstrated directly that PMA increases the association of CD4 with coated pits. Immunofluorescent staining of internalized CD4 showed that PMA also diverted CD4 from the early endosome-plasma membrane recycling pathway to a mannose 6-phosphate receptor-containing late endosomal compartment. In lymphoid or p56lck-expressing transfected cells, these effects were preceded by the PMA-induced dissociation of CD4 and p56lck, which released CD4 and made possible increased endocytosis and altered intracellular trafficking. Together these results indicate that phorbol esters have multiple effects on the normal endocytosis and trafficking of CD4, and suggest that phosphorylation may influence the interaction of CD4 with coated pits.

HIVgp120 activates autoreactive CD4-specific T cell responses by unveiling of hidden CD4 peptides during processing.

T cells are made tolerant only to those self-peptides that are presented in sufficient amounts by antigen-presenting cells. They ignore cryptic self-determinants, such as either those not generated by processing machinery or generated in insufficient amounts. It is anticipated that mechanisms that either change antigen processing or increase the yield of previously "invisible" peptides may be capable of inducing T cell priming and, if they are self-maintained, may sustain autoimmune diseases. Herein, we demonstrate for the first time a mechanism by which the gp120 human immunodeficiency virus-I, by downregulating plasma membrane CD4 and increasing its processing, unveils hidden CD4 epitopes, inducing an autoimmune-specific T cell response.

Human immunodeficiency virus type 1 escape from cyclotriazadisulfonamide-induced CD4-targeted entry inhibition is associated with increased neutralizing antibody susceptibility.

Continuous specific downmodulation of CD4 receptor expression in T lymphocytes by the small molecule cyclotriazadisulfonamide (CADA) selected for the CADA-resistant human immunodeficiency virus type 1 (HIV-1) NL4.3 virus containing unique mutations in the C4 and V5 regions of gp120, likely stabilizing the CD4-binding conformation. The amino acid changes in Env were associated with decreased susceptibility to anti-CD4 monoclonal antibody treatment of the cells and with higher susceptibility of the virus to soluble CD4. In addition, the acquired ability of a CADA-resistant virus to infect cells with low CD4 expression was associated with an increased susceptibility of the virus to neutralizing antibodies from sera of several HIV-1-infected patients.

Exposure to benzene induces oxidative stress, alters the immune response and expression of p53 in gasoline filling workers.

BACKGROUND: Chronic exposure to benzene can lead to deleterious effects on many biological systems including blood and blood-forming organs. We investigated the adverse effects of benzene among workers occupationally exposed to benzene in India. METHODS: Four hundred twenty-eight gasoline filling workers occupationally exposed to benzene and 78 unexposed individuals were recruited for this study. Benzene concentration was determined by gas chromatography, reactive oxygen species (ROS) by dichlorofluorescin diacetate (DCFH-DA) method, malondialdehyde (MDA) by thiobarbituric acid reactive substances assay (TBARS), total superoxide dismutase (T-SOD) by RANSOD kit and glutathione (GSH) by 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) reaction, respectively. CD4, CD8, IgG were carried out by using fluorescence activated cell sorter (FACS Calibur) and mRNA expression of p53 by reverse transcriptase PCR (RT-PCR). RESULTS: A significant increase in the concentration of benzene and its byproducts in both blood and urine were found in the workers compared with the controls. The levels of ROS and MDA were significantly elevated, and GSH and total T-SOD were decreased in the workers compared with the controls. A statistically significant decrease in the immunoglobulin levels, CD4T cells, CD4/CD8 ratio was observed in workers (vs. controls), whereas no significant difference was observed in CD8T cells. p53 gene expression was markedly higher in workers than in controls. CONCLUSION: Occupational exposure to benzene causes oxidative stress, immune suppression and increases the expression of tumor-suppressing gene p53 in gasoline filling workers. These bio-functional markers might be useful in screening and surveillance for occupational hazard.

HIV entry inhibitors: progress in development and application.

This review discusses recent progress in the development of anti-HIV agents, with emphasis on small molecule HIV-1 entry inhibitors. The entry inhibitors primarily target HIV-1 envelope glycoproteins or the cellular receptors, CD4 and chemokine receptors. Two of the entry inhibitors, enfuvirtide and maraviroc, have been approved by the US FDA for AIDS therapy. The drug resistance associated with some of the entry inhibitors will also be discussed.

Deltamethrin-Induced Immunotoxicity and its Protection by Quercetin: An Experimental Study.

BACKGROUND: Deltamethrin (DLM) is a type 2 pyrethroid insecticide used in agriculture and home to control pests. However, emerging reports have indicated the immunotoxicity of DLM. OBJECTIVE: Thus, in the current investigation, we have checked the immune-protective role of quercetin in DLM-induced immunotoxicity by using in silico and in vitro techniques. RESULTS: In silico results have shown good interaction of quercetin towards immune cell receptors (T & B cell receptors). The findings of in vitro studies indicated the decrease in oxidative stress which is elevated by DLM in concentration & time-dependent manner. The increased caspases-3 activity was decreased by treatment of quercetin. The apoptosis induced by DLM in thymus and spleen was suppressed only at higher concentration (50µg/ml) of quercetin. Finally, the phenotypic changes due to DLM were restored by quercetin. CONCLUSION: Quercetin has strong binding affinity towards CD4, CD8 and CD28, CD45 receptors and protects the thymocytes and splenocytes against DLM-induced apoptotic signaling pathways.

Involvement of central immunity in uncomplicated diverticular disease.

OBJECTIVE: The pathogenesis of symptoms of uncomplicated diverticular disease (UDD) is unclear, but changes in gut microflora and physiologic inflammation may be implicated. The objective of the study was to investigate the distribution of gut homing lymphocytes in peripheral blood and intestinal mucosa of UDD patients, and the effects of luminal antibiotic treatment. MATERIAL AND METHODS: Ten UDD patients and 10 age- and gender-matched healthy subjects underwent peripheral blood sampling, and colonoscopy with biopsies taken from the transverse and sigmoid colon. Treatment consisted of a 2-month course of rifaximin 1.2 g/day for 15 days/month. Blood sample and mucosal biopsies were repeated in UDD patients at the end of treatment. Flow cytometry was performed using monoclonal antibodies (CD3, CD4, CD8, CD25, CD19, CD45, CD62L, CD103). RESULTS: In peripheral blood, both CD4+ and CD8+/CD103+ were significantly higher in patients at baseline than in controls (0.95% versus 0.36%, and 0.5% versus 0.09%, respectively). After treatment, peripheral CD4+/CD103+ decreased (0.27%), while CD8+/CD103+ did not change (0.35%); on the contrary, peripheral CD25+ increased, the CD4+ subpopulation showing significantly higher levels than those in controls. No difference was found between lymphocytes in the diverticular sigmoid mucosa of patients at baseline and those in controls, but there was a significant decrease in CD8+/CD62L+ after treatment. In the normal transverse colon, CD4+/CD62L+ of patient at baseline were significantly lower than in controls. After treatment, CD4+/CD103+ levels significantly increased, while CD8+/CD62L+ levels significantly decreased. CONCLUSIONS: Both central and mucosal immunity may be modified in UDD patients, with an increased recruitment of CD103+ lymphocytes. A 2-month course of rifaximin appears to reduce CD103+ levels, suggesting a decrease in mobilization of mucosal homing.

[Effect of enterosorption on immunologic parameters of patients with colorectal cancer in the postoperative period].

Our investigation was carried out on an assumption that end results among patients radically-treated for colorectal cancer might be improved by use of enteroabsorption. The study group included 17, controls--13 patients with diagnostically verified stage I-III tumors. Mixed sorbent (microcellulose + polysorb) (6g) was administered, once a week, on the average of 20 days after operation. Immunological vigor was assayed 3 weeks after surgery: immunoglobulin levels--by turbodimetric method, cellular profile of lymphocytes--monoclonal antibodies to cell markers CD3, CD4, CD8, CD16 and CD22. As a result of adjuvant treatment CD22 (B-lymphocytes) concentration increased significantly--from 17.70 to 21.66 (22%), while CD16 (innate killers) both in absolute numbers (19%) and by percentage points (9%). Circulating immunocomplex levels in the sorbent-treatment group were significantly lower (37.44 ths units) than in control (48 ths units) (average 28%). No relapse or metastases were reported in either group.

Drug resistance from preferred antiretroviral regimens for HIV infection in South Africa: A modeling study.

BACKGROUND: Tenofovir-containing regimens comprise the preferred first-line antiretroviral therapy (ART) in many countries including South Africa, where utilization of second-line regimens is limited. Considerable HIV drug resistance has occurred among persons failing tenofovir-containing first-line ART. We evaluated drug resistance at the population level using mathematical modeling. SETTING: Heterosexual HIV epidemic in KwaZulu-Natal, South Africa. METHODS: We constructed a stochastic individual-based model and simulated scenarios of ART implementation, either CD4-based (threshold < 500 cells/mL) or Fast-track (81% coverage by 2020), with consideration of major drug-associated mutations (M184V, K65R and non-nucleoside reverse transcriptase inhibitor (NNRTI)). Using base case and uncertainty analyses, we assessed (majority) drug resistance levels. RESULTS: By 2030, the median total resistance (proportion of HIV-infected persons with drug resistance) is predicted to reach 31.4% (interquartile range (IQR): 16.5%-50.2%) with CD4-based ART, decreasing to 14.5% (IQR: 7.7%-25.8%) with Fast-track implementation. In both scenarios, we find comparably high prevalence (~80%) of acquired NNRTI-associated, M184V and K65R mutations. Over 48% of individuals with acquired resistance harbor dual, 44% triple and 7% just single drug mutations. Drug-resistant HIV is predicted to comprise 40% (IQR: 27%-50%) of incident infections, while 70% of prevalent transmitted resistance is NNRTI-associated. At 2018, the projected total resistance is 15% (IQR: 7.5%-25%), with 18% (IQR: 13%-24%) of incident infections from transmitted drug-resistant HIV. CONCLUSIONS: WHO-recommended preferred first-line ART could lead to substantial drug resistance. Effective surveillance of HIV drug resistance and utilization of second-line as well as alternative first-line regimens is crucial.

Impact of immunosuppressive drugs on CD4+CD25+FOXP3+ regulatory T cells: does in vitro evidence translate to the clinical setting?

Success of solid-organ transplantation requires the continuous administration of immunosuppressive drugs to prevent graft rejection. The currently prescribed immunosuppressive medication targets the immune system in a nonspecific fashion, leading to debilitating side effects that diminish patient survival and quality of life. Therefore, it is important to minimize immunosuppression, but this requires the development of alternative therapeutic strategies to induce and maintain transplant tolerance. One such strategy would be to allow and facilitate the induction of alloantigen-specific immune regulation by regulatory T cells (Treg). Recent experimental studies indicate that several commonly used immunosuppressive drugs have detrimental effects on the induction and function of Treg, whereas other drugs appear to spare these cells or may even be beneficial. These differential effects may be explained by differences in signaling pathways between Treg and effector T cells. In this review, we provide a comprehensive overview of the current literature on the effects of immunosuppressive drugs on CD4+CD25+FOXP3+ Treg and discuss whether these in vitro data are substantiated by in vivo evidence from the clinic. A greater understanding of the impact of immunosuppression on Treg may help to create future opportunities to manipulate the host allo-immune response and achieve operational tolerance in transplantation.

Sargassum fusiforme fraction is a potent and specific inhibitor of HIV-1 fusion and reverse transcriptase.

Sargassum fusiforme (Harvey) Setchell has been shown to be a highly effective inhibitor of HIV-1 infection. To identify its mechanism of action, we performed bioactivity-guided fractionation on Sargassum fusiforme mixture. Here, we report isolation of a bioactive fraction SP4-2 (S. fusiforme), which at 8 mug/ml inhibited HIV-1 infection by 86.9%, with IC50 value of 3.7 mug. That represents 230-fold enhancement of antiretroviral potency as compared to the whole extract. Inhibition was mediated against both CXCR4 (X4) and CCR5 (R5) tropic HIV-1. Specifically, 10 mug/ml SP4-2 blocked HIV-1 fusion and entry by 53%. This effect was reversed by interaction of SP4-2 with sCD4, suggesting that S. fusiforme inhibits HIV-1 infection by blocking CD4 receptor, which also explained observed inhibition of both X4 and R5-tropic HIV-1. SP4-2 also inhibited HIV-1 replication after virus entry, by directly inhibiting HIV-1 reverse transcriptase (RT) in a dose dependent manner by up to 79%. We conclude that the SP4-2 fraction contains at least two distinct and biologically active molecules, one that inhibits HIV-1 fusion by interacting with CD4 receptor, and another that directly inhibits HIV-1 RT. We propose that S. fusiforme is a lead candidate for anti-HIV-1 drug development.

TAK-242 selectively suppresses Toll-like receptor 4-signaling mediated by the intracellular domain.

TAK-242, a small-molecule antisepsis agent, has shown to suppress lipopolysaccharide (LPS)-induced inflammation. In this study, we demonstrate that TAK-242 is a selective inhibitor of Toll-like receptor (TLR)-4 signaling. TAK-242 almost completely suppressed production of nitric oxide (NO) or tumor necrosis factor (TNF)-alpha induced by a TLR4-specific ligand, ultra-pure LPS, in mouse RAW264.7, human U-937 and P31/FUJ cells, whereas this agent showed little effect on other TLR ligands, Pam(3)CSK(4) (TLR1/2), peptidoglycan (TLR2/6), double strand RNA (TLR3), R-848 (TLR7) and CpG oligonucleotide (TLR9). Furthermore, TAK-242 potently inhibited nuclear factor (NF)-kappaB activation induced by ultra-pure LPS in HEK293 cells transiently expressing TLR4 and co-receptors, myeloid differentiation protein-2 (MD2) and CD14, whereas this agent showed little effect on other TLRs, TLR1/2, TLR2/6, TLR3, TLR5, TLR7 and TLR9. TAK-242 also inhibited ligand-independent NF-kappaB activation resulting from over-expression of TLR4. Although chimera receptors, which are consist of the extracellular domain of CD4 and the intracellular domain of human or mouse TLR4, showed constitutive NF-kappaB activation, TAK-242 potently inhibited the signaling from CD4-TLR4 chimera receptors. In contrast, the NF-kappaB activation mediated by TLR4 adaptors, myeloid differentiation factor 88 (MyD88), TIR-associated protein (TIRAP), Toll/IL-1R homology (TIR)-domain-containing adaptor protein-inducing interferon-beta (TRIF) or TRIF-related adaptor molecule (TRAM) was not affected by TAK-242. TAK-242 is therefore a selective inhibitor of signaling from the intracellular domain of TLR4 and represents a novel therapeutic approach to the treatment of TLR4-mediated diseases.

Immunoregulatory mechanisms and CD4-CD8- (double negative) T cell subpopulations in human cutaneous leishmaniasis: a balancing act between protection and pathology.

Cellular immune responses directed against protozoan parasites are key for controlling pathogen replication and disease resolution. However, an uncontrolled, or improperly controlled, response can be deleterious to the host in terms of both allowing for the establishment of pathology, as well as less effective establishment of memory responses. Human cutaneous leishmaniasis is a disease caused by the infection with Leishmania spp. following a bite from the sandfly, the natural vector of this disease. Tens of millions worldwide are currently infected with Leishmania and no effective vaccines have been developed to date. In the face of the complexity presented by the interaction between a host (humans) with the parasite, Leishmania, and the fact that this parasite is inoculated by another complex, biologically active, vector, the sandfly, it is clearly important to study the immunoregulatory mechanisms that are induced in humans naturally infected by this parasite if we hope to develop effective vaccines and immunotherapeutic treatments in the future. Our laboratory has focused over the years on the study of the local and systemic T cell response during the first episode of cutaneous leishmaniasis suffered by individuals before they undergo antimony treatment. The goal of this review is to briefly outline our findings with hopes of putting our most recent studies concerning the dichotomy between alpha/beta TCR and gamma/delta TCR expressing, CD4-CD8- (double negative-DN) T cells in the context of a balanced immune response against Leishmania and to discuss the implications of these findings toward our understanding of human leishmaniasis.