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Lists the research papers to be published in the succeeding issues of the "European Journal of Biochemistry." "The structure of DNA junctions and their interaction with enzymes," by D.R. Duckett and colleagues; "CD4 gene transcription is transiently repressed during differentiation of myeloid cells to macrophage-like cells," by F.X. Pimentel-Muiñoz and colleagues; "Malonate decarboxylase of Malonomas rubra: a novel type of biotin-containing acetyl-enzyme," by H. Hilbi and colleagues.

Pulmonary fibrosis involves various types of immune cells and soluble mediators, including TGF‐β and IL‐35, a recently identified heterodimeric cytokine that belongs to the IL‐12 cytokine family. However, the effect of regulatory IL‐35 may play an important role in fibrotic diseases. The aim of this paper is to explore the immunoregulatory role of IL‐35 in the development of fibrosis in interstitial lung disease (ILD). To gain a better understanding of this issue, the concentrations of IL‐35 and different profibrotic cytokines in fibrotic (F‐ILD) and non‐fibrotic (NF‐ILD) patients by ELISA were compared to that of intracellular IL‐35 and IL‐17 on CD4+ T cells stimulated in the presence of BAL or with different ratios of recombinant IL‐35 (rIL‐35) and TGF‐β (rTGF‐β), which were evaluated by flow cytometry. We observed that BAL concentration of IL‐35 was lower in F patients (p < 0.001) and was negatively correlated with concentrations of TGF‐β (p < 0.001) and IL‐17 (p < 0.001). In supplemented cell cultures, BAL from NF but not F patients enhanced the percentage of IL‐35 + CD4+ T (p < 0.001) cells and decreased the percentage of IL‐17 + CD4+ T cells (p < 0.001). The percentage of IL‐35 + CD4+ T cells correlated positively with BAL concentration of IL‐35 (p = 0.02), but correlated negatively with BAL concentrations of IL‐17 (p = 0.007) and TGF‐β (p = 0.01). After adjusting the concentrations of recombinant cytokines to establish a TGF‐β: IL‐35 ratio of 1:4, an enhanced percentage of IL‐35 + CD4+ T cells (p < 0.001) but a decreased percentage of IL‐17 + CD4+ T cells (p < 0.001) was observed. After adding recombinant IL‐35 to the BAL from F patients until a 1:4 ratio of TGF‐β: IL‐35 was reached, a significantly increased percentage of IL‐35 + CD4+ T cells (p < 0.001) and a decreased percentage of IL‐17 + CD4+ T cells (p = 0.003) was found. These results suggest that IL‐35 may induce an anti‐fibrotic response, regulating the effect of TGF‐β and the inflammatory response on CD4+ T cells. In addition, the TGF‐β: IL‐35 ratio in BAL has been shown to be a potential biomarker to predict the outcome of F patients with ILD. [ABSTRACT FROM AUTHOR]

Broadly neutralizing antibodies are proposed as therapeutic and prophylactic agents against HIV‐1, but their potency and breadth are less than optimal. This study describes the immunization of a llama with the prefusion‐stabilized HIV‐1 envelope (Env) trimer, BG505 DS‐SOSIP, and the identification and improvement of potent neutralizing nanobodies recognizing the CD4‐binding site (CD4bs) of vulnerability. Two of the vaccine‐elicited CD4bs‐targeting nanobodies, G36 and R27, when engineered into a triple tandem format with llama IgG2a‐hinge region and human IgG1‐constant region (G36×3‐IgG2a and R27×3‐IgG2a), neutralized 96% of a multiclade 208‐strain panel at geometric mean IC80s of 0.314 and 0.033 µg mL−1, respectively. Cryo‐EM structures of these nanobodies in complex with Env trimer revealed the two nanobodies to neutralize HIV‐1 by mimicking the recognition of the CD4 receptor. To enhance their neutralizing potency and breadth, nanobodies are linked to the light chain of the V2‐apex‐targeting broadly neutralizing antibody, CAP256V2LS. The resultant human‐llama bispecific antibody CAP256L‐R27×3LS exhibited ultrapotent neutralization and breadth exceeding other published HIV‐1 broadly neutralizing antibodies, with pharmacokinetics determined in FcRn‐Fc mice similar to the parent CAP256V2LS. Vaccine‐elicited llama nanobodies, when combined with V2‐apex broadly neutralizing antibodies, may therefore be able to fulfill anti‐HIV‐1 therapeutic and prophylactic clinical goals. [ABSTRACT FROM AUTHOR]

Natural killer ( NK) cells provide an immediate first line of defence against viral infections. Memory responses, maintained by CD4+ T cells, require exposure to viral antigen and provide long-term protection against future infections. It is known that NK cells can promote the development of the adaptive response through cytokine production and cross-talk with antigen-presenting cells. In this paper however, we summarize a series of recent publications, in mouse models and for the first time in man, with the unifying message that rapid viral antigen control by the innate immune system limits antigen exposure to CD4+ cells thereby abrogating the development of a memory response. We discuss the significant implication of these studies on viral treatment strategies and immunization models. [ABSTRACT FROM AUTHOR]

Many successes have been achieved in HIV care in low- and middle-income countries (LMIC): increased number of HIV-infected individuals receiving antiretroviral treatment (ART), wide decentralization, reduction in morbidity and mortality and accessibility to cheapest drugs. However, these successes should not hide existing failures and difficulties. In this paper, we underline several key challenges. First, ensure long-term financing, increase available resources, in order to meet the increasing needs, and redistribute the overall budget in a concerted way amongst donors. Second, increase ART coverage and treat the many eligible patients who have not yet started ART. Competition amongst countries is expected to become a strong driving force in encouraging the least efficient to join better performing countries. Third, decrease early mortality on ART, by improving access to prevention, case-finding and treatment of tuberculosis and invasive bacterial diseases and by getting people to start ART much earlier. Fourth, move on from WHO 2006 to WHO 2010 guidelines. Raising the cut-off point for starting ART to 350 CD4/mm3 needs changing paradigm, adopting opt-out approach, facilitating pro-active testing, facilitating task shifting and increasing staff recruitments. Phasing out stavudine needs acting for a drastic reduction in the costs of other drugs. Scaling up routine viral load needs a mobilization for lower prices of reagents and equipments, as well as efforts in relation to point-of-care automation and to maintenance. The latter is a key step to boost the utilization of second-line regimens, which are currently dramatically under prescribed. Finally, other challenges are to reduce lost-to-follow-up rates; manage lifelong treatment and care for long-term morbidity, including drug toxicity, residual AIDS and HIV-non-AIDS morbidity and aging-related morbidity; and be able to face unforeseen events such as socio-political and military crisis. An old African proverb states that the growth of a deep-rooted tree cannot be stopped. Our tree is well rooted in existing field experience and is, therefore, expected to grow. In order for us to let it grow, long-term cost-effectiveness approach and life-saving evidence-based programming should replace short-term budgeting approach. [ABSTRACT FROM AUTHOR]

Copyright of Tropical Medicine & International Health is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Peripheral blood CD4 CD45RO T cells activated in vitro are able to induce expression of tumour necrosis factor-α (TNF-α) in monocytes via a contact-dependent mechanism. Activation is achieved either with interleukin-2 (IL-2)/IL-6/TNF-α over an 8-day period or cross-linking CD3 using anti-CD3 antibody for 48 hr. In this paper, we show that the p38 mitogen-activated protein kinase (MAPK) signalling pathway played different roles in the generation of effector function in these two types of activated T cells. In anti-CD3 activated T cells, p38 MAPK is a negative regulator for anti-CD3 induced cell proliferation and has no significant effect on the acquisition of either the effector function (induction of monocyte-derived TNF-α) or production of T-cell cytokines. In contrast, the p38 MAPK signalling pathway is required for the acquisition of cytokine-induced effector function and promotes cell proliferation and cytokine production. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes, a Gram-positive bacterium, is the causative agent for the disease called listeriosis. This pathogen utilizes host cell surface proteins such as E-cadherin or c-Met in order to invade eukaryotic cells. The invasion via c-Met depends on the bacterial protein InlB that activates c-Met phosphorylation and internalization mimicking in many regards HGF, the authentic c-Met ligand. In this paper, we demonstrate that the activation of c-Met induced by InlB is dependent on CD44v6, a member of the CD44 family of transmembrane glycoproteins. Inhibiting CD44v6 by means of a blocking peptide, a CD44v6 antibody or CD44v6-specific siRNA prevents the activation of c-Met induced by InlB. Subsequently, signalling, scattering and the entry of InlB-coated beads into host cells are also impaired by CD44v6 blocking reagents. For the entry process, ezrin, a protein that links the CD44v6 cytoplasmic domain to the cytoskeleton, is required as well. Most importantly, this collaboration between c-Met and CD44v6 contributes to the invasion of L. monocytogenes into target cells as demonstrated by a drastic decrease in bacterial invasion in the presence of blocking agents such as the CD44v6 peptide or antibody. [ABSTRACT FROM AUTHOR]

α2,6‐sialylation, catalyzed by α2,6‐sialyltransferase (ST6GAL1), plays a pivotal role in immune responses. However, the role of ST6GAL1 in the pathogenesis of ulcerative colitis (UC) remains unknown. ST6GAL1 mRNA is highly expressed in UC tissues compared with the corresponding adjacent normal tissues, and α2,6‐sialylation is significantly increased in the colon tissues of patients with UC. The expression of ST6GAL1 and proinflammatory cytokines, such as interleukin (IL)‐2, IL‐6, IL‐17, and interferon‐gamma, is also increased. The number of CD4+ T cells increases in UC patients. St6gal1 gene knockout (St6gal1−/‐) rats are established by clustered regularly interspaced short palindromic repeats (CRISPR)‐associated gene knockout system. St6gal1 deficiency reduces the levels of pro‐inflammatory cytokines and alleviates colitis symptoms in UC model rats. Ablation of α2,6‐sialylation inhibits the transport of the TCR to lipid rafts and suppresses CD4+ T‐cell activation. The attenuation of TCR signaling downregulates the expression of NF‐κB in ST6GAL1‐/‐ CD4+ T‐cells. Moreover, NF‐κB could bind to the ST6GAL1 promoter to increase its transcription. Ablation of ST6GAL1 downregulates the expression of NF‐κB and reduces the production of proinflammatory cytokines to relieve UC pathogenesis, which is a potential novel target for the clinical treatment of UC. [ABSTRACT FROM AUTHOR]

A systemic and local inflammatory immune imbalance is thought to be the cause of traumatic tracheal stenosis (TS). However, with CD4+ T lymphocytes being the predominant immune cells in TS, the mechanism of action and recruitment has not been described. In our research, using flow cytometry, ELISA, immunofluorescence, and Transwell chamber assays, the expression, distribution, and potential chemotactic function of CD4+ T cells in TS patients were examined before and after treatment. The results showed that the untreated group had significantly more CD4+ T cells and their secreted TGF‐β1 than the treated group. Additionally, the untreated group's CD4+ T cells showed a significant rise in CCL22 and CCL1, as well as a larger proportion of CCR4 and CCR8. CD4+ T cells and CD68+ macrophages located in TS also expressed CCL1 and CCL22. In vitro, anti‐CCL1 and anti‐CCL22 can partially block the chemoattractant effect of TS bronchoalveolar lavage (BAL) on purified CD4+ T cells. The findings of this study indicated that TS contained unbalanced CD4 immune cells that were actively recruited locally by CCR4/CCL22 and CCR8/CCL1. As a result, it is anticipated that CD4 immune rebalancing can serve as a novel treatment for TS. [ABSTRACT FROM AUTHOR]

This paper describes a model of successful immunotherapy of advanced lymphoma based on the selective elimination of cycling tumour-induced suppressor T cells. It shows that a single injection of the anti-mitotic drug, vinblasting (Vb), results in complete regression of a large L5178Y lymphoma and its metastases, but not if it is growing in an immunocompetent host. Vb-induced, immunologically mediated tumour regression was dependent on the anti-tumour function of CD8+ T cells, because regression was prevented by depleting the host of this subset of T cells 24 hr after Vb was given. Regression was also prevented by infusing the host with Vb-sensitive, CD4+ T cells from a turnout-bearing donor. These and other results are in keeping with the interpretation that Vbinduced regression of the L5178Y lymphoma depends on the ability of the drug to eliminate CD4+ suppressor T ceils that are replicating, and to spare non-replicating CD8+ effector cells, it is suggested that at an advanced stage of growth of the L5178Y lymphoma the host possesses an acquired population of antigen-primed CD8+ effector T cells that are unable to become activated in response to abundant tumour antigen because of the dominant influence of CD4+ suppressor cells. Activation of these CD8+ T cells was indicated by the finding that they were rapidly converted from being cyclophosphamide (Cy) resistant to being highly Cy sensitive within 48 hr of giving Vb. [ABSTRACT FROM AUTHOR]

The leucocyte common antigen, CD45 (T200, Ly-5), exists in a number of isoforms generated by differential usage of three exons that code for an extracellular region close to the NH2 terminus. Use of antibodies to different isoforms of CD45 has lead to the identification of two subsets of CD4+ T cells in rat, man and mouse. Data on the functions of the two rat CD4+ T-cell subsets isolated on the basis of different levels of expression of exon B (and/or C) are largely concordant with those obtained from the two subsets of human CD4 + T cells defined by their levels of expression of exon A. However, results presented in this paper on the CD45 phenotype of rat T cells that produce interferon-gamma (IFN-γ) are not compatible with the human data, if it is assumed that there are only two functional subsets of CD4+ T cells. The data could, in principle, be reconciled if the expression of exons A and B defined three rather than two subsets, and this possibility has now been examined in man where monoclonal antibodies against both A and B exon products are available. The results show the presence of a third CD4+ T-cell subset and that this extra subset is contained within the population originally shown to provide memory T-cell function. [ABSTRACT FROM AUTHOR]

Introduction: The frequencies and functions of T stem cell memory (TSCM) subsets vary in autoimmune diseases. We evaluated the frequencies of CD4+ and CD8+ TSCM subsets as well as their PD‐1 expression levels in patients with T1D. Methods: Blood samples were collected from new case (NC) (n = 15), and long‐term (LT) (n = 15) groups and healthy controls (n = 15). Five subsets of T cells including TCM(CD4+/CD8+ CCR7+ CD45RO+ CD95+), TCMhi (CD4+/CD8+ CCR7+ CD45ROhi CD95+), TEM(CD4+/CD8+ CCR7− CD45RO+ CD95+), TSCM(CD4+/CD8+ CCR7+ CD45RO− CD95+), and T naive (CD4+/CD8+ CCR7+ CD45RO− CD95−) were detected by flow‐cytometry. Results: The frequency of CD4+ TSCM was higher in NC patients than LT patients and controls (p <.0001 and p =.0086, respectively). A higher percentage of the CD8+ T naive cells was shown in NC patients as compared with LT and healthy individuals (p =.0003 and p =.0002, respectively). An increased level of PD‐1 expression was observed on the CD4+TCM and TCMhi cells in LT patients as compared with healthy controls (p =.0037 and p =.0145, respectively). Also, the higher PD‐1 expression was observed on the CD8+ TCM and TCMhi in NC and LT patients as compared with controls (p =.0068 and p <.0001; p =.0012 and p =.0012, respectively). Conclusion: Considering TSCMs' capacities to generate all memory and effector T cells, our results may suggest a potential association between the increased frequencies of TSCMs and T1D progression. [ABSTRACT FROM AUTHOR]

The pathogenic immune response in celiac disease (CeD) is orchestrated by phenotypically distinct CD4+ T cells that recognize gluten epitopes in the context of disease‐associated HLA‐DQ allotypes. Cells with the same distinct phenotype, but with elusive specificities, are increased across multiple autoimmune conditions. Here, whether sorting of T cells based on their distinct phenotype (Tphe cells) yields gluten‐reactive cells in CeD is tested. The method′s efficiency is benchmarked by parallel isolation of gluten‐reactive T cells (Ttet cells), using HLA‐DQ:gluten peptide tetramers. From gut biopsies of 12 untreated HLA‐DQ2.5+ CeD patients, Ttet+/Tphe+, Ttet−/Tphe+, and Ttet−/Tphe− cells are sorted for single‐cell T‐cell receptor (TCR)‐sequencing (n = 8) and T‐cell clone (TCC)‐generation (n = 5). The generated TCCs are TCR sequenced and tested for their reactivity against deamidated gluten. Gluten‐reactivity is observed in 91.2% of Ttet+/Tphe+ TCCs, 65.3% of Ttet−/Tphe+ TCCs and 0% of Ttet−/Tphe− TCCs. TCR sequencing reveals clonal expansion and sequence sharing across patients, features reflecting antigen‐driven responses. The feasibility to isolate antigen‐specific CD4+ T cells by the sole use of phenotypic markers in CeD outlines a potential avenue for characterizing disease‐driving CD4+ T cells in autoimmune conditions. [ABSTRACT FROM AUTHOR]

Introduction: Adolescents living with HIV are subject to multiple co‐morbidities, including growth retardation and immunodeficiency. We describe growth and CD4 evolution during adolescence using data from the Collaborative Initiative for Paediatric HIV Education and Research (CIPHER) global project. Methods: Data were collected between 1994 and 2015 from 11 CIPHER networks worldwide. Adolescents with perinatally acquired HIV infection (APH) who initiated antiretroviral therapy (ART) before age 10 years, with at least one height or CD4 count measurement while aged 10–17 years, were included. Growth was measured using height‐for‐age Z‐scores (HAZ, stunting if <‐2 SD, WHO growth charts). Linear mixed‐effects models were used to study the evolution of each outcome between ages 10 and 17. For growth, sex‐specific models with fractional polynomials were used to model non‐linear relationships for age at ART initiation, HAZ at age 10 and time, defined as current age from 10 to 17 years of age. Results: A total of 20,939 and 19,557 APH were included for the growth and CD4 analyses, respectively. Half were females, two‐thirds lived in East and Southern Africa, and median age at ART initiation ranged from <3 years in North America and Europe to >7 years in sub‐Saharan African regions. At age 10, stunting ranged from 6% in North America and Europe to 39% in the Asia‐Pacific; 19% overall had CD4 counts <500 cells/mm3. Across adolescence, higher HAZ was observed in females and among those in high‐income countries. APH with stunting at age 10 and those with late ART initiation (after age 5) had the largest HAZ gains during adolescence, but these gains were insufficient to catch‐up with non‐stunted, early ART‐treated adolescents. From age 10 to 16 years, mean CD4 counts declined from 768 to 607 cells/mm3. This decline was observed across all regions, in males and females. Conclusions: Growth patterns during adolescence differed substantially by sex and region, while CD4 patterns were similar, with an observed CD4 decline that needs further investigation. Early diagnosis and timely initiation of treatment in early childhood to prevent growth retardation and immunodeficiency are critical to improving APH growth and CD4 outcomes by the time they reach adulthood. [ABSTRACT FROM AUTHOR]

MicroRNA are important regulators of CD4 T cell differentiation, altering the balance between the immunogenic and tolerogenic pathways. Studies in mice with micro RNA-deficient T cells have revealed defects in differentiation into the regulatory T cell lineage; however, the individual micro RNA responsible have remained elusive. A recent paper in The EMBO Journal uses a systematic screen to find a novel cooperative action between an inducible and a constitutive micro RNA in aiding regulatory T cell induction. [ABSTRACT FROM AUTHOR]

In the tumor microenvironment, T cells, B cells, and many other cells play important and distinct roles in anti‐tumor immunotherapy. Although the immune checkpoint blockade and adoptive cell transfer can elicit durable clinical responses, only a few patients benefit from these therapies. Increased understanding of tumor‐infiltrating immune cells can provide novel therapies and drugs that induce a highly specific anti‐tumor immune response to certain groups of patients. Herein, the recent research progress on tumor‐infiltrating B cells and T cells, including CD8+ T cells, CD4+ T cells, and exhausted T cells and their role in anti‐tumor immunity, is summarized. Moreover, several anti‐tumor therapy approaches are discussed based on different immune cells and their prospects for future applications in cancer treatment. [ABSTRACT FROM AUTHOR]

Introduction: Persistence of HIV‐1, causing chronic immune activation, is a key determinant of premature senescence. Early antiretroviral therapy (ART) has been associated with a reduced HIV‐1 reservoir in children with perinatally acquired HIV‐1 (PHIV), but its impact on the senescence process is an open question. We investigated the association between HIV‐1 reservoir and biological and immune ageing profile in PHIV enrolled in the multicentre cross‐sectional study CARMA (Child and Adolescent Reservoir Measurements on early suppressive ART) conducted within the EPIICAL (Early treated Perinatally HIV Infected individuals: Improving Children's Actual Life) consortium. Methods: Between September 2017 and June 2018, CARMA enrolled 40 PHIV who started ART before 2 years of age and had undetectable viremia for at least 5 years before sampling date. Samples from 37 children with a median age of 13.8 years were available for this study. HIV‐1 DNA copies on CD4 cells, relative telomere length (marker of cellular senescence) and levels of T‐cell receptor rearrangement excision circle (TREC, marker of thymic output) on CD4 and CD8 cells were quantified by qPCR. Immunological profile was assessed by flow cytometry. Associations between molecular and phenotypic markers, HIV‐1 reservoir and age at ART initiation were explored using a multivariable Poisson regression. Results: Higher HIV‐1 reservoir was associated (p<0.001) with telomere shortening (incidence rate ratio [IRR] = 0.15 [0.13–0.17]), immunosenescence (CD28–CD57+, IRR = 1.23 [1.21–1.26]) and immunoactivation (CD38+ HLADR+, IRR = 7.29 [6.58–8.09]) of CD4 cells. Late ART initiation (after 6 months of age) correlated with higher HIV‐1 reservoir levels (552 [303–1001] vs. 89 [56–365] copies/106 CD4 cells, p = 0.003) and percentage of CD4 senescent cells (2.89 [1.95–6.31] vs. 1.02 [0.45–2.69, p = 0.047). TREC levels in CD8 cells were inversely associated with HIV‐1 reservoir (IRR = 0.77 [0.76–0.79]) and were significantly lower in late treated PHIV (1128 [486–1671] vs. 2278 [1425–3314], p = 0.042). Conclusions: Later ART initiation is associated with higher HIV‐1 reservoir size, which correlates with increased telomere shortening and senescence of CD4 cells. Timing of ART initiation in infancy has long‐term consequences on the immune and biological ageing profile of children with perinatally acquired HIV‐1. [ABSTRACT FROM AUTHOR]

Acquired immune deficiency syndrome is an epidemic infectious disease which is caused by the human immunodeficiency virus (HIV) and that has proliferated across worldwide. It has been a matter of concern for the scientific community to develop an antiretroviral therapy, which will prompt a rapid decline in viral abundance. With this motivation, this study proposes the design of a robust super twisting sliding mode controller based on output information for an uncertain HIV infection model. The control objective is to decrease the concentration of infected CD4+ T cells to a specified level by drug administration using only the output information of the uncertain HIV infection model which is total CD4+ T cell concentration. The robust output-feedback controller has been developed in combination with a robust exact differentiator, functioning as an observer. The reported analysis demonstrates that the approach proposed here is capable of ensuring robust performance under several operating conditions, measurement and modelling error, parametric uncertainties and external disturbances and the simulation results prove the proficiency of the controller proposed. [ABSTRACT FROM AUTHOR]

Immune thrombocytopenia (ITP) is an acquired autoimmune disease characterized by an immune mediated decrease in platelet number. Disturbance of CD4+ T‐cell homeostasis with simultaneous decrease of CD4+CD25+Foxp3+ regulatory T cells (Tregs) as well as unrestricted proliferation and activation of peripheral CD4+ effector T cells underpin the pathophysiology of ITP. Indirubin is an active ingredient of a traditional Chinese herb called Indigofera tinctoria L. which is clinically used for the treatment of ITP patients. Whether indirubin targets the Tregs/effector T cell‐axis to restore platelet number is unknown. In our in vitro studies, Indirubin could significantly enhance the number and function of Tregs and meanwhile dampen the activation of effector T cells in a dose‐dependent manner. Indirubin was observed to restore the expression of programmed cell‐death 1 (PD1) and phosphatase and tensin homolog (PTEN) on the CD4+ T cells of ITP patients, leading to the subsequent attenuation of the AKT/mTOR pathway. Furthermore, these observations were recapitulated in an active murine model of ITP with a prominent platelet response. Thus, our results identified a potentially novel mechanism of the therapeutic action of indirubin in the treatment of ITP through regulating the homeostasis of CD4+ T cells in a PD1/PTEN/AKT signalling pathway. [ABSTRACT FROM AUTHOR]

Sustained adaptive immunity to pathogens provides effective protection against infections, and effector cells located at the site of infection ensure rapid response to the challenge. Both are essential for the success of vaccine development. To explore new vaccination approach against Mycobacterium tuberculosis (M.tb) infection, we have shown that Rv3615c, identified as ESX‐1 substrate protein C of M.tb but not expressed in BCG, induced a dominant Th1‐type response of CD4+ T cells from patients with tuberculosis pleurisy, which suggests a potential candidate for vaccine development. But subcutaneous immunization with Rv3615c induced modest T‐cell responses systemically, and showed suboptimal protection against virulent M.tb challenge at the site of infection. Here, we use a mouse model to demonstrate that intranasal immunization with Rv3615c induces sustained capability of adaptive CD4+ T‐ and B‐cell responses in lung parenchyma and airway. Rv3615c contains a dominant epitope of mouse CD4+ T cells, Rv3615c41‐50, and elicits CD4+ T‐cell response with an effector–memory phenotype and multi‐Th1‐type cytokine coexpressions. Since T cells resident at mucosal tissue are potent at control of infection at early stage, our data show that intranasal immunization with Rv3615c promotes a sustained regional immunity to M.tb, and suggests a potency in control of M.tb infection. Our study warranties a further investigation of Rv3615c as a candidate for development of effective vaccination against M.tb infection. [ABSTRACT FROM AUTHOR]

Summary: Upon encounter with their cognate antigen, naive CD4 T cells become activated and are induced to differentiate into several possible T helper (Th) cell subsets. This differentiation depends on a number of factors including antigen‐presenting cells, cytokines and co‐stimulatory molecules. The strength of the T‐cell receptor (TCR) signal, related to the affinity of TCR for antigen and antigen dose, has emerged as a dominant factor in determining Th cell fate. Recent studies have revealed that TCR signals of high or low strength do not simply induce quantitatively different signals in the T cells, but rather qualitatively distinct pathways can be induced based on TCR signal strength. This review examines the recent literature in this area and highlights important new developments in our understanding of Th cell differentiation and TCR signal strength. [ABSTRACT FROM AUTHOR]

Abstract: As a proinflammatory cytokine, CD137 (4‐1BB, TNFRSF9) is present in membrane‐bound and soluble forms. Increased expression of CD137 was recently found in T cells in human atherosclerotic plaques. However, the exact role of CD137 in ischemic stroke is not clear. In this study we analyzed the protein levels of soluble CD137 (sCD137) and the expression of CD137 on CD4+ T cells in the peripheral blood of patients with acute atherothrombotic stroke by using the cytometry beads array (CBA) and flow cytometry. Within 24 hours of onset, the stroke patients showed elevated levels of sCD137 (2.7 pg/ml) and CD137 expression on CD4+ T cells (4.9 ± 3.2%) compared with normal controls (1.1 pg/ml, P < 0.01; 1.3 ± 1.0%, P < 0.01). Alterations in CD137 expression may enhance ischemia‐induced inflammatory responses via bidirectional signaling and, consequently, aggravate brain injury in early stages of this disorder. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Modelling suggests that early diagnosis and immediate antiretroviral therapy (ART) among key populations would have a substantial impact in reducing HIV transmission and mortality in Vietnam. An implementation research project of “test‐and‐treat” among people who inject drugs (PWID) was developed to inform effective roll‐out of such interventions. Methods: “Test‐and‐treat” was offered to PWID in two high burden provinces, Thai Nguyen and Thanh Hoa. The interventions comprised the offer of biannual HIV testing and immediate ART, irrespective of CD4 count. PWID were enrolled between April 2014 and July 2015 and followed up for 12 months, and retention, HIV viral load (VL) and risk behaviours were assessed. Retention in care of this prospective cohort was compared with the retention among men enrolled in care in the preceding period (April 2012 to March 2013) at the same clinics when ART was initiated at CD4 cell count ≤350 cells/mm3. Results: In total, 287 HIV positive PWID started immediate ART. The majority (98%) were men; median age was 34; and median (interquartile range) CD4 count was 199 (50 to 402) cells/mm3. After 12 months, 238 participants (83%) were retained on ART, and 205 achieved viral suppression (<1000 copies/mL) (92% among those in whom VL was measured, 71% overall). Baseline CD4 count ≤100 cells/mm3 and history of imprisonment were associated with lower retention and viral suppression, while engagement in methadone maintenance was associated with higher retention. Retention in care was higher in the “test‐and‐treat” cohort (83%) compared with men enrolled in care in the preceding period (78%), primarily because lost‐to‐follow‐up during pre‐ART care was eliminated. No decline in consistent condom use and clean needle use was observed. Conclusions: Early ART initiation resulted in successful treatment outcomes among PWID, with no observed increase in self‐reported risk behaviours, suggesting feasibility and potential effectiveness of “test‐and‐treat” approach. The results also call for differentiated care for PWID, including promoting early diagnosis and engagement in methadone maintenance therapy while enhancing care for those with advanced HIV disease and history of imprisonment. [ABSTRACT FROM AUTHOR]

Summary: Although regulatory T‐cells (Tregs) have been shown to be expanded in acute dengue, their role in pathogenesis and their relationship to clinical disease severity and extent of viraemia have not been fully evaluated. The frequency of Tregs was assessed in 56 adult patients with acute dengue by determining the proportion of forkhead box protein 3 (FoxP3) expressing CD4+ CD25+T‐cells (FoxP3+ cells). Dengue virus (DENV) viral loads were measured by quantitative real‐time polymerase chain reaction (PCR) and DENV‐specific T‐cell responses were measured by ex‐vivo interferon (IFN)‐γ enzyme‐linked immunospot (ELISPOT) assays to overlapping peptide pools of DENV‐NS3, NS1 and NS5. CD45RA and CCR4 were used to phenotype different subsets of T‐cells and their suppressive potential was assessed by their expression of cytotoxic T lymphocyte‐antigen 4 (CTLA‐4) and Fas. While the frequency of FoxP3+ cells in patients was significantly higher (P < 0·0001) when compared to healthy individuals, they did not show any relationship with clinical disease severity or the degree of viraemia. The frequency of FoxP3+ cells did not correlate with either ex‐vivo IFN‐γ DENV‐NS3‐, NS5‐ or NS1‐specific T‐cell responses. FoxP3+ cells of patients with acute dengue were predominantly CD45RA+ FoxP3low, followed by CD45RA‐FoxP3low, with only a small proportion of FoxP3+ cells being of the highly suppressive effector Treg subtype. Expression of CCR4 was also low in the majority of T‐cells, with only CCR4 only being expressed at high levels in the effector Treg population. Therefore, although FoxP3+ cells are expanded in acute dengue, they predominantly consist of naive Tregs, with poor suppressive capacity. [ABSTRACT FROM AUTHOR]

Copyright of Tropical Medicine & International Health is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction: The Streamlined Antiretroviral Therapy Initiation Strategy (START-ART) study found that a theory-based intervention using opinion leaders to inform and coach health care providers about the risks of treatment delay, provision of point of care (POC) CD4 testing machines (PIMA) and reputational incentives, led to rapid rise in ART initiation. We used qualitative research methods to explore mechanisms of provider behaviour change. Methods: We conducted in-depth interviews (IDIs) with 24 health care providers and nine study staff to understand perceptions, attitudes and the context of changes in ART initiation practices. Analyses were informed by the Theoretical Domains Framework. Results: Rapid dissemination of new practices was enabled in the environmental context of an existing relationship based on communication, implementation and accountability between Makerere University Joint AIDS Program (MJAP), a Ugandan University-affiliated organization that provided technical oversight for HIV service delivery at the health facilities where the intervention was implemented, and a network of health facilities operated by the Uganda Ministry of Health. Coaching carried out by field coordinators from MJAP strengthened influence and informal accountability for carrying out the intervention. Frontline health workers held a pre-existing strong sense of professional identity. They were proud of attainment of new knowledge and skills and gratified by providing what they perceived to be higher quality care. Peer counsellors, who were not explicitly targeted in the intervention design, effectively substituted some functions of health care providers; as role models for successful ART uptake, they played a crucial role in creating demand for rapid ART initiation through interactions with patients. Point of care (POC) CD4 testing enabled immediate action and relieved providers from frustrations of lost or delayed laboratory results, and led to higher patient satisfaction (due to reduced costs because of ability to initiate ART right away, requiring fewer return trips to clinic). Conclusions: Qualitative data revealed that a multicomponent intervention to change provider behaviour succeeded in the context of strong institutional and individual relationships between a University-affiliated organization, government facilities, and peer health workers (who acted as a crucial link between stakeholders) and the community. Fostering stable institutional relationships between institutional actors (non-governmental organization (NGOs) and ministry-operated facilities) as well as between facilities and the community (through peer health workers) can enhance uptake of innovations targeting the HIV cascade in similar clinical settings. [ABSTRACT FROM AUTHOR]

CD4 T cells help immune responses, but knowledge of how memory CD4 T cells are regulated and how they regulate adaptive immune responses and induce immunopathology is limited. Using adoptive transfer of virus-specific CD4 T cells, we show that naive CD4 T cells undergo substantial expansion following infection, but can induce lethal T helper type 1-driven inflammation. In contrast, memory CD4 T cells exhibit a biased proliferation of T follicular helper cell subsets and were able to improve adaptive immune responses in the context of minimal tissue damage. Our analyses revealed that type I interferon regulates the expansion of primary CD4 T cells, but does not seem to play a critical role in regulating the expansion of secondary CD4 T cells. Strikingly, blockade of type I interferon abrogated lethal inflammation by primary CD4 T cells following viral infection, despite that this treatment increased the numbers of primary CD4 T-cell responses. Altogether, these data demonstrate important aspects of how primary and secondary CD4 T cells are regulated in vivo, and how they contribute to immune protection and immunopathology. These findings are important for rational vaccine design and for improving adoptive T-cell therapies against persistent antigens. [ABSTRACT FROM AUTHOR]

Induction of tolerance is a key mechanism to maintain or to restore immunological homeostasis. Here we show that Foxp3+ regulatory T (Treg) cells use Dickkopf-1 ( DKK-1) to regulate T-cell-mediated tolerance in the T-cell-mediated autoimmune colitis model. Treg cells from DKK-1 hypomorphic doubleridge mice failed to control CD4+ T-cell proliferation, resulting in CD4 T-cell-mediated autoimmune colitis. Thymus-derived Treg cells showed a robust expression of DKK-1 but not in naive or effector CD4 T cells. DKK-1 expression in Foxp3+ Treg cells was further increased upon T-cell receptor stimulation in vitro and in vivo. Interestingly, Foxp3+ Treg cells expressed DKK-1 in the cell membrane and the functional inhibition of DKK-1 using DKK-1 monoclonal antibody abrogated the suppressor function of Foxp3+ Treg cells. DKK-1 expression was dependent on de novo protein synthesis and regulated by the mitogen-activated protein kinase pathway but not by the canonical Wnt pathway. Taken together, our results highlight membrane-bound DKK-1 as a novel Treg-derived mediator to maintain immunological tolerance in T-cell-mediated autoimmune colitis. [ABSTRACT FROM AUTHOR]

Several host factors have been implicated in resistance to HIV infection in individuals who remain HIV-seronegative despite exposure. In a cohort of HIV-serodiscordant heterosexual couples, we investigated interactions between systemic inflammation and T-cell activation in resistance to HIV infection. Males and females in stable long-term relationships with either HIV-infected or uninfected partners were recruited, blood T-cell activation ( CD38, HLA- DR, CCR5 and Ki67) and plasma cytokine concentrations were evaluated. The HIV-negative exposed individuals had significantly lower frequencies of CCR5+ CD4+ and CD8+ T cells than unexposed individuals. Mean fluorescence intensity of CCR5 expression on CD4+ T cells was significantly lower in HIV-negative exposed than unexposed individuals. Protective CCR5 haplotypes ( HHA/ HHF*2, HHF*2/ HHF*2, HHC/ HHF*2, HHA/ HHA, HHA/ HHC and HHA/ HHD) tended to be over-represented in exposed compared with unexposed individuals (38% versus 28%, P = 0·58) whereas deleterious genotypes ( HHC/ HHD, HHC/ HHE, HHD/ HHE, HHD/ HHD and HHE/ HHE) were under-represented (26% versus 44%; P = 0·16). Plasma concentrations of interleukin-2 ( P = 0·02), interferon- γ ( P = 0·05) and granulocyte-macrophage colony-stimulating factor ( P = 0·006) were lower in exposed compared with unexposed individuals. Activation marker expression and systemic cytokine concentrations were not influenced by gender. We conclude that the dominant signature of resistance to HIV infection in this cohort of exposed but uninfected individuals was lower T-cell CCR5 expression and plasma cytokine concentrations. [ABSTRACT FROM AUTHOR]

This study aims to explore effects of 1,25( OH)2D3 and vitamin D receptor ( VDR) on peripheral CD4+/ CD8+ double-positive (DP) T lymphocytes in systemic lupus erythematosus ( SLE). MRL- LPr/ LPr mice with SLE ( n = 20) and normal MRL mice ( n = 20) were assigned into the control group (normal mice, without feeding with 1,25( OH)2D3), the 1,25( OH)2D3 group ( SLE mice, feeding with 1,25( OH)2D3), the VDR-knock-in + 1,25( OH)2D3 group ( SLE mice, VDR-knock-in, feeding with 1,25( OH)2D3) and the VDR-knockout group (normal mice, VDR-knockout, without feeding with 1,25( OH)2D3) ( n = 10 per group). Levels of T lymphocytes were measured by flow cytometry. The mRNA and proteins expressions of inflammatory factors were measured by qRT- PCR and ELISA. Extracellular signal-regulated kinase-1/2 ( ERK1/2) expression was measured by Western blotting. Compared with normal mice, SLE mice showed reduced levels of CD4+, CD4+/ CD8+ ratio, and DP lymphocytes. The levels of SLE-related indicators all increased significantly, followed with severe skin ulcers and urinary system infection. With the increase in time, skin ulcers and urinary system infection were significantly improved, levels of CD4+, CD4+/ CD8+ ratio, and DP lymphocytes increased, and levels of SLE-related indicators all decreased in the 1,25( OH)2D3 group. There were no significant changes in bioindicators in the control and the VDR-knock-in + 1,25( OH)2D3 groups. The symptoms of SLE gradually occurred in the VDR-knockout group. This study demonstrates that VDR and 1,25( OH)2D3 could elevate CD4+/ CD8+ DP T lymphocytes and reduce expressions of inflammatory factors, thus inhibiting the development and progression of SLE. [ABSTRACT FROM AUTHOR]

Introduction: An important determinant of the effectiveness of HIV treatment programs is the capacity of sites to implement recommended services and identify systematic changes needed to ensure that invested resources translate into improved patient outcomes. We conducted a survey in 2014 of HIV care and treatment sites in the seven regions of the International epidemiologic Database to Evaluate AIDS (IeDEA) Consortium to evaluate facility characteristics, HIV prevention, care and treatment services provided, laboratory capacity, and trends in the comprehensiveness of care compared to data obtained in the 2009 baseline survey. Methods: Clinical staff from 262 treatment sites in 45 countries in IeDEA completed a site survey from September 2014 to January 2015, including Asia-Pacific with Australia (n = 50), Latin America and the Caribbean (n = 11), North America (n = 45), Central Africa (n = 17), East Africa (n = 36), Southern Africa (n = 87), and West Africa (n = 16). For the 55 sites with complete data from both the 2009 and 2014 survey, we evaluated change in comprehensiveness of care. Results: The majority of the 262 sites (61%) offered seven essential services (ART adherence, nutritional support, PMTCT, CD4+ cell count testing, tuberculosis screening, HIV prevention, and outreach). Sites that were publicly funded (64%), cared for adults and children (68%), low or middle Human Development Index (HDI) rank (68%, 68%), and received PEPFAR support (71%) were most often fully comprehensive. CD4+ cell count testing was universally available (98%) but only 62% of clinics offered it onsite. Approximately two-thirds (69%) of sites reported routine viral load testing (44-100%), with 39% having it onsite. Laboratory capacity to monitor antiretroviral-related toxicity and diagnose opportunistic infections varied widely by testing modality and region. In the subgroup of 55 sites with two surveys, comprehensiveness of services provided significantly increased across all regions from 2009 to 2014 (5.7 to 6.5, p < 0.001). Conclusions: The availability of viral load monitoring remains suboptimal and should be a focus for site capacity, particularly in East and Southern Africa, where the majority of those initiating on ART reside. However, the comprehensiveness of care provided increased over the past 5 years and was related to type of funding received (publicly funded and PEPFAR supported). [ABSTRACT FROM AUTHOR]

It is demonstrated that the reachability paradigm from variable structure control theory is a suitable framework to monitor and predict the progression of the human immunodeficiency virus (HIV) infection following initiation of antiretroviral therapy (ART). A manifold is selected which characterises the infection-free steady-state. A model of HIV infection together with an associated reachability analysis is used to formulate a dynamical condition for the containment of HIV infection on the manifold. This condition is tested using data from two different HIV clinical trials which contain measurements of the CD4+ T cell count and HIV load in the peripheral blood collected from HIV infected individuals for the six month period following initiation of ART. The biological rates of the model are estimated using the multi-point identification method and data points collected in the initial period of the trial. Using the parameter estimates and the numerical solutions of the model, the predictions of the reachability analysis are shown to be consistent with the clinical diagnosis at the conclusion of the trial. The methodology captures the dynamical characteristics of eventual successful, failed and marginal outcomes. The findings evidence that the reachability analysis is an appropriate tool to monitor and develop personalised antiretroviral treatment. [ABSTRACT FROM AUTHOR]

Adoptive cell immunotherapy for human diseases, including the use of T cells modified to express an anti-tumour T-cell receptor ( TCR) or chimeric antigen receptor, is showing promise as an effective treatment modality. Further advances would be accelerated by the availability of a mouse model that would permit human T-cell engineering protocols and proposed genetic modifications to be evaluated in vivo. NOD- scid IL2rγ null ( NSG) mice accept the engraftment of mature human T cells; however, long-term evaluation of transferred cells has been hampered by the xenogeneic graft-versus-host disease ( GVHD) that occurs soon after cell transfer. We modified human primary CD4+ T cells by lentiviral transduction to express a human TCR that recognizes a pancreatic beta cell-derived peptide in the context of HLA- DR4. The TCR-transduced cells were transferred to NSG mice engineered to express HLA- DR4 and to be deficient for murine class II MHC molecules. CD4+ T-cell-depleted peripheral blood mononuclear cells were also transferred to facilitate engraftment. The transduced cells exhibited long-term survival (up to 3 months post-transfer) and lethal GVHD was not observed. This favourable outcome was dependent upon the pre-transfer T-cell transduction and culture conditions, which influenced both the kinetics of engraftment and the development of GVHD. This approach should now permit human T-cell transduction protocols and genetic modifications to be evaluated in vivo, and it should also facilitate the development of human disease models that incorporate human T cells. [ABSTRACT FROM AUTHOR]

Background Major histocompatibility complex ( MHC) I and II expression is not normally detected on sarcolemma, but is detected with lymphocytic infiltrates in immune-mediated myositis ( IMM) of humans and dogs and in dysferlin-deficient muscular dystrophy. Hypothesis/Objectives To determine if sarcolemmal MHC is expressed in active IMM in horses, if MHC expression is associated with lymphocytic subtype, and if dysferlin is expressed in IMM. Animals Twenty-one IMM horses of Quarter Horse-related breeds, 3 healthy and 6 disease controls (3 pasture myopathy, 3 amylase-resistant polysaccharide storage myopathy [ PSSM]). Methods Immunohistochemical staining for MHC I, II, and CD4+, CD8+, CD20+ lymphocytes was performed on archived muscle of IMM and control horses. Scores were given for MHC I, II, and lymphocytic subtypes. Immunofluorescent staining for dysferlin, dystrophin, and a-sarcoglycan was performed. Results Sarcolemmal MHC I and II expression was detected in 17/21 and 15/21 of IMM horses, respectively, and in specific fibers of PSSM horses, but not healthy or pasture myopathy controls. The CD4+, CD8+, and CD20+ cells were present in 20/21 IMM muscles with CD4+ predominance in 10/21 and CD8+ predominance in 6/21 of IMM horses. Dysferlin, dystrophin, and a-sarcoglycan staining were similar in IMM and control muscles. Conclusions and clinical importance Deficiencies of dysferlin, dystrophin, and a-sarcoglycan are not associated with IMM. Sarcolemmal MHC I and II expression in a proportion of myofibers of IMM horses in conjunction with lymphocytic infiltration supports an immune-mediated etiology for IMM. The MHC expression also occured in specific myofibers in PSSM horses in the absence of lymphocytic infiltrates. [ABSTRACT FROM AUTHOR]

The immune system is composed of a variety of cells that act in a coordinated fashion to protect the organism against a multitude of different pathogens. The great variability of existing pathogens corresponds to a similar high heterogeneity of the immune cells. The study of individual immune cells, the fundamental unit of immunity, has recently transformed from a qualitative microscopic imaging to a nearly complete quantitative transcriptomic analysis. This shift has been driven by the rapid development of multiple single-cell technologies. These new advances are expected to boost the detection of less frequent cell types and transient or intermediate cell states. They will highlight the individuality of each single cell and greatly expand the resolution of current available classifications and differentiation trajectories. In this review we discuss the recent advancement and application of single-cell technologies, their limitations and future applications to study the immune system. [ABSTRACT FROM AUTHOR]

Indoleamine 2,3-dioxygenase ( IDO) is expressed in antigen-presenting cells and exerts immunosuppressive effects on CD4+ T cells. One mechanism is through the inhibition of aerobic glycolysis. Another prerequisite for T-cell proliferation and differentiation into effector cells is increased fatty acid ( FA) synthesis. The effect of IDO on enzymes involved in FA synthesis was evaluated in primary human cells both in mixed lymphocyte reactions in the presence or not of the IDO inhibitor 1- dl-methyl-tryptophan, and in stimulated CD4+ T cells in the presence or not of the general control non-derepressible 2 ( GCN2) kinase activator tryptophanol ( TRP). IDO or TRP inhibited cell proliferation. By assessing the level of GCN2 kinase or mammalian target of rapamycin complex 1 substrates along with a kynurenine free system we showed that IDO exerts its effect mainly through activation of GCN2 kinase. IDO or TRP down-regulated ATP-citrate lyase and acetyl coenzyme A carboxylase 1, key enzymes involved in FA synthesis. Also, IDO or TRP altered the expression of enzymes that control the availability of carbon atoms for FA synthesis, such as lactate dehydrogenase-A, pyruvate dehydrogenase, glutaminase 1 and glutaminase 2, in a way that inhibits FA synthesis. In conclusion, IDO through GCN2 kinase activation inhibits CD4+ T-cell proliferation and down-regulates key enzymes that directly or indirectly promote FA synthesis, a prerequisite for CD4+ T-cell proliferation and differentiation into effector cell lineages. [ABSTRACT FROM AUTHOR]

Objective Multiple sclerosis ( MS) is a disease of the central nervous system with marked heterogeneity in several aspects including pathological processes. Based on infiltrating immune cells, deposition of humoral factors and loss of oligodendrocytes and/or myelin proteins, four lesion patterns have been described. Pattern II is characterized by antibody and complement deposition in addition to T-cell infiltration. MS is considered a T-cell-mediated disease, but until now the study of pathogenic T cells has encountered major challenges, most importantly the limited access of brain-infiltrating T cells. Our objective was to identify, isolate, and characterize brain-infiltrating clonally expanded T cells in pattern II MS lesions. Methods We used next-generation sequencing to identify clonally expanded T cells in demyelinating pattern II brain autopsy lesions, subsequently isolated these as T-cell clones from autologous cerebrospinal fluid and functionally characterized them. Results We identified clonally expanded CD8+ but also CD4+ T cells in demyelinating pattern II lesions and for the first time were able to isolate these as live T-cell clones. The functional characterization shows that T cells releasing Th2 cytokines and able to provide B cell help dominate the T-cell infiltrate in pattern II brain lesions. Interpretation Our data provide the first functional evidence for a putative role of Th2/Tc2 cells in pattern II MS supporting the existence of this pathogenic phenotype and questioning the protective role that is generally ascribed to Th2 cells. Our observations are important to consider for future treatments of pattern II MS patients. [ABSTRACT FROM AUTHOR]

HIV-infected individuals with severe immunodeficiency are at risk of opportunistic infection (OI). Tuberculosis (TB) may occur without substantial immune suppression suggesting an early and sustained adverse impact of HIV on Mycobacterium tuberculosis (MTB)-specific cell mediated immunity (CMI). This prospective observational cohort study aimed to observe differences in OI-specific and MTB-specific CMI that might underlie this. Using polychromatic flow cytometry, we compared CD4+ responses to MTB, cytomegalovirus (CMV), Epstein-Barr virus (EBV) and Candida albicans in individuals with and without HIV infection. MTB-specific CD4+ T-cells were more polyfunctional than virus specific (CMV/EBV) CD4+ T-cells which predominantly secreted IFN-gamma (IFN-γ) only. There was a reduced frequency of IFN-γ and IL-2 (IL-2)-dual-MTB-specific cells in HIV-infected individuals, which was not apparent for the other pathogens. MTB-specific cells were less differentiated especially compared with CMV-specific cells. CD127 expression was relatively less frequent on MTB-specific cells in HIV co-infection. MTB-specific CD4+ T-cells PD-1 expression was infrequent in contrast to EBV-specific CD4+ T-cells. The variation in the inherent quality of these CD4+ T-cell responses and impact of HIV co-infection may contribute to the timing of co-infectious diseases in HIV infection. [ABSTRACT FROM AUTHOR]

Targeting of antigens to the endocytic uptake receptor DEC205 resulted in enhanced antigen presentation by dendritic cells ( DCs). In combination with adjuvants for DC maturation, proteins coupled to an antibody against DEC205 induced strong pathogen-specific immune responses, whereas without additional adjuvant tolerance could be induced. As less is known about DNA vaccines encoding DEC205-targeted antigens, we explored the immunogenicity and efficacy of a dendritic cell-targeted DNA vaccine against influenza A virus ( IAV) delivered by electroporation. Although coupling of haemagglutinin to a single-chain antibody against DEC205 enhanced antigen presentation on MHC class II and activation of T-cell receptor-transgenic CD4 T cells, the T-cell responses induced by the targeted DNA vaccine in wild-type BALB/c mice were significantly reduced compared with DNA encoding non-targeted antigens. Consistently, these mice were less protected against an IAV infection. Adoptive transfer experiments were performed to assess the fate of the antigen-specific T cells in animals vaccinated with DNA encoding DEC205-targeted antigens. By this, we could exclude the general deletion of antigen-specific T cells as cause for the reduced efficacy, but observed a local expansion of antigen-specific regulatory T cells, which could suppress the activation of effector cells. In conclusion, DNA vaccines encoding DEC205-targeted antigens induce peripheral tolerance rather than immunity in our study. Finally, we evaluated our DNA vaccines as prophylactic or therapeutic treatment in an allergen-induced asthma mouse model. [ABSTRACT FROM AUTHOR]

Basophils are known to modulate the phenotype of CD4+ T cells and to enhance T helper type 2 responses in vitro and in vivo. In this study, we demonstrate that murine basophils inhibit proliferation of CD4+ T cells in autologous and allogeneic mixed lymphocyte reactions. The inhibition is independent of Fas and MHC class II, but dependent on activation of basophils with subsequent release of interleukin-4 ( IL-4) and IL-6. The inhibitory effect of basophils on T-cell proliferation can be blocked with antibodies against IL-4 and IL-6 and is absent in IL-4/ IL-6 double-deficient mice. In addition, we show that basophils and IL-4 have beneficial effects on disease activity in a murine model of acute graft-versus-host disease (Gv HD). When basophils were depleted with the antibody MAR-1 before induction of Gv HD, weight loss, Gv HD score, mortality and plasma tumour necrosis factor levels were increased while injection of IL-4 improved Gv HD. Basophil-depleted mice with Gv HD also have increased numbers of CD4+ T cells in the mesenteric lymph nodes. Our data show for the first time that basophils suppress autologous and allogeneic CD4+ T-cell proliferation in an IL-4-dependent manner. [ABSTRACT FROM AUTHOR]

Peripheral induction of regulatory T (Treg) cells provides essential protection from inappropriate immune responses. CD4+ T cells that lack endogenous mi RNAs are impaired to differentiate into Treg cells, but the relevant mi RNAs are unknown. We performed an overexpression screen with T-cell-expressed mi RNAs in naive mouse CD4+ T cells undergoing Treg differentiation. Among 130 candidates, the screen identified 29 mi RNAs with a negative and 10 mi RNAs with a positive effect. Testing reciprocal Th17 differentiation revealed specific functions for miR-100, miR-99a and miR-10b, since all of these promoted the Treg and inhibited the Th17 program without impacting on viability, proliferation and activation. miR-99a cooperated with miR-150 to repress the expression of the Th17-promoting factor mTOR. The comparably low expression of miR-99a was strongly increased by the Treg cell inducer 'retinoic acid', and the abundantly expressed miR-150 could only repress Mtor in the presence of miR-99a. Our data suggest that induction of Treg cell differentiation is regulated by a mi RNA network, which involves cooperation of constitutively expressed as well as inducible mi RNAs. [ABSTRACT FROM AUTHOR]

The frequency of CD4+ Foxp3+ regulatory T (Treg) cells is often significantly increased in the blood of tumour-bearing mice and people with cancer. Moreover, Treg cell frequencies are often higher in tumours compared with blood and lymphoid organs. We wished to determine whether certain chemokines expressed within the tumour mass selectively recruit Treg cells, thereby contributing to their enrichment within the tumour-infiltrating lymphocyte pool. To achieve this goal, the chemokine profile of carcinogen-induced fibrosarcomas was determined, and the chemokine receptor expression profiles of both CD4+ Foxp3− and CD4+ Foxp3+ T cells were compared. These analyses revealed that the tumours are characterized by expression of inflammatory chemokines ( CCL2, CCL5, CCL7, CCL8, CCL12, CXCL9, CXCL10 and CX3 CL1), reflected by an enrichment of activated Foxp3− and Foxp3+ T cells expressing T helper type 1-associated chemokine receptors. Notably, we found that CXCR3+ T cells were significantly enriched in the tumours although curiously we found no evidence that CXCR3 was required for their recruitment. Instead, CXCR3 marks a population of activated Foxp3− and Foxp3+ T cells, which use multiple and overlapping ligand receptor pairs to guide their migration to tumours. Collectively, these data indicate that enrichment of Foxp3+ cells in tumours characterized by expression of inflammatory chemokines, does not occur via a distinct chemokine axis, thus selective chemokine blockade is unlikely to represent a meaningful therapeutic strategy for preventing Treg cell accumulation in tumours. [ABSTRACT FROM AUTHOR]

There is a progressive increase in cardiovascular disease with declining renal function, unexplained by traditional risk factors. A CD4+ T-cell subpopulation ( CD4+ CD28−), activated by human heat-shock protein 60 ( hHSP 60), expands in patients with acute coronary syndrome and is associated with vascular damage. These cells exhibit cytotoxicity via expression of activating killer cell-immunoglobulin-like receptor KIR2 DS2, mainly in the absence of inhibitory KIR2 DL3. We investigated expansion of these cells and the pathogenic role of the KIR in non-dialysis-dependent chronic kidney disease ( NDD- CKD) and end-stage haemodialysis-dependent renal disease ( HD- ESRD) patients. CD4+ CD28− cells were present in 27% of the NDD- CKD and HD- ESRD patients (8-11% and 10-11% of CD4+ compartment, respectively). CD4+ CD28− cells were phenotyped for KIR and DAP12 expression. Cytotoxicity was assessed by perforin and pro-inflammatory function by interferon- γ expression on CD4+ CD28− clones ( NDD- CKD n = 97, HD- ESRD n = 262). Thirty-four per cent of the CD4+ CD28− cells from NDD- CKD expressed KIR2 DS2 compared with 56% in HD- ESRD patients ( P = 0·03). However, 20% of clones expressed KIR2 DL3 in NDD- CKD compared with 7% in HD- ESRD patients ( P = 0·004). DAP12 expression in CD28− 2 DS2+ clones was more prevalent in HD- ESRD than NDD- CKD (92% versus 60%; P < 0·001). Only 2 DS2+ 2 DL3− DAP12+ clones were cytotoxic in response to hHSP 60. CD4+ CD28− cells exhibited increased KIR2 DS2, reduced KIR2 DL3 and increased DAP12 expression in HD- ESRD compared with NDD- CKD patients. These findings suggest a gradual loss of expression, functionality and protective role of inhibitory KIR2 DL3 as well as increased cytotoxic potential of CD4+ C28− cells with progressive renal impairment. Clonal expansion of these T cells may contribute to heightened cardiovascular events in HD-ESRD. [ABSTRACT FROM AUTHOR]

Tumour progression is associated with immune-suppressive conditions that facilitate the escape of tumour cells from the regimen of immune cells, subsequently paralysing the host defence mechanisms. Induction of CD4+ CD25+ FoxP3+ T regulatory (Treg) cells has been implicated in the tumour immune escape mechanism, although the novel anti-cancer treatment strategies targeting Treg cells remain unknown. The focus of this study is to define the interaction between tumour and immune system, i.e. how immune tolerance starts and gradually leads to the induction of adaptive Treg cells in the tumour microenvironment. Our study identified hyperactivated mitogen-activated protein kinase kinase ( MEK)/extracellular signal-regulated kinase ( ERK) -signalling as a potential target for reversing Treg cell augmentation in breast cancer patients. In more mechanistic detail, pharmacological inhibitors of MEK/ ERK signalling inhibited transforming growth factor- β ( TGF- β) production in tumour cells that essentially blocked TGF- β- SMAD3/ SMAD4-mediated induction of CD25/interleukin-2 receptor α on CD4+ T-cell surface. As a result high-affinity binding of interleukin-2 on those cells was prohibited, causing lack of Janus kinase 1 ( JAK1)/ JAK3-mediated signal transducer and activator of transcription 3 ( STAT3)/ STAT5 activation required for FoxP3 expression. Finally, for a more radical approach towards a safe MEK inhibitor, we validate the potential of multi-kinase inhibitor curcumin, especially the nano-curcumin made out of pure curcumin with greater bioavailability; in repealing tumour-shed TGF- β-induced Treg cell augmentation. [ABSTRACT FROM AUTHOR]

X- DING- CD4 is a novel phosphatase mediating antiviral responses to HIV-1 infection. This protein is constitutively expressed and secreted by HIV-1 resistant CD4+ T cells and its m RNA transcription is up-regulated in peripheral blood mononuclear cells from HIV-1 elite controllers. The secreted/soluble X- DING- CD4 protein form is of particular importance because it blocks virus transcription when added to HIV-1 susceptible cells. The present study aimed to determine the contribution of this factor to the induction of the antiviral response in target cells. We found that soluble X- DING- CD4 enters cells by endocytosis and that influx of this protein induced transcription of interferon-α and endogenous X- DING- CD4 m RNA in transformed CD4+ T cells and primary macrophages. Treatment of HIV-1 susceptible cells with exogenous X- DING- CD4 caused depletion of phosphorylated p50 and p65 nuclear factor kappa β subunits and a significant reduction in p50/p65 nuclear factor kappa β binding to the HIV-1 long terminal repeat. Taken together, these findings indicate a novel antiviral mechanism mediated by the influx of soluble X- DING- CD4, its signaling to promote self-amplification, and functional duality as an endogenous innate immunity effector and exogenous factor regulating gene expression in bystander cells. [ABSTRACT FROM AUTHOR]

Wolbachia is an endosymbiotic bacterium of the filarial nematode Brugia malayi. The symbiotic relationship between Wolbachia and its filarial host is dependent on interactions between the proteins of both organisms. However, little is known about Wolbachia proteins that are involved in the inflammatory pathology of the host during lymphatic filariasis. In the present study, we cloned, expressed and purified Wolbachia surface protein (r-wsp) from Wolbachia and administered it to mice, either alone or in combination with infective larvae of B. malayi (Bm-L3) and monitored the developing immune response in infected animals. Our results show that spleens and mesenteric lymph nodes of mice immunized with either r-wsp or infected with Bm-L3 show increased percentages of CD4+ T helper type 17 (Th17) cells and Th1 cytokines like interferon- γ and interleukin-2 (IL-2) along with decreased percentages of regulatory T cells, Th2 cytokines like IL-4 and IL-10 and transforming growth factor β (TGF- β) levels in culture supernatants of splenocytes. These observations were stronger in mice immunized with r-wsp alone. Interestingly, when mice were first immunized with r-wsp and subsequently infected with Bm-L3, percentages of CD4+ Th17 cells and Th1 cytokines increased even further while that of regulatory T cells, Th2 cytokines and TGF- β levels decreased. These results for the first time show that r-wsp acts synergistically with Bm-L3 in promoting a pro-inflammatory response by increasing Th17 cells and at the same time diminishes host immunological tolerance by decreasing regulatory T cells and TGF- β secretion. [ABSTRACT FROM AUTHOR]

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Soluble MHCII (sMHCII) molecules are present in body fluids of healthy individuals and are considered to be involved in the maintenance of self tolerance, and are also related to various diseases. Their concentration increases during in vivo antigen-specific tolerogenic stimulation and it was recently shown that exosome-mediated tolerance is MHCII dependent. At the cellular level, sMHCII proteins compete with membrane MHCII for T-cell receptor binding on CD4+ T cells. Immunoaffinity purification techniques isolated sMHCII antigens from the serum of human serum albumin (HSA) -tolerant mice as a single highly glycosylated protein of ~ 60 000 molecular weight, specifically interacting with anti-class II antibodies in Western blotting and ELISA. Mass spectroscopy showed that these sMHCII proteins were loaded with the tolerogenic peptide as well as multiple self peptides. At the cellular level, sMHCII suppressed antigen-specific, and to a lesser degree antigen-non-specific, spleen cell proliferation and induced CD25 in naive T cells. In T cells activated by antigen-seeded macrophages, sMHCII decreased CD28 and increased CTLA-4 protein expression, while decreasing interleukin-2 and increasing interleukin-10 production. In this case, sMHCII proteins were shown to decrease ZAP-70 and LAT phosphorylation. The results presented here for the first time provide evidence for the role of sMHCII proteins in immune response suppression and maintenance of tolerance, revealing novel regulatory mechanisms for immune system manipulation. [ABSTRACT FROM AUTHOR]

The envelope spike of HIV-1, which consists of three external gp120 and three transmembrane gp41 glycoproteins, recognizes its target cells by successively binding to its primary CD4 receptor and a coreceptor molecule. Until recently, atomic-resolution structures were available primarily for monomeric HIV-1 gp120, in which the V1, V2 and V3 variable loops were omitted (gp120core), in complex with soluble CD4 (s CD4). Differences between the structure of HIV gp120core in complex with s CD4 and the structure of unliganded simian immunodeficiency virus gp120core led to the hypothesis that gp120 undergoes a major conformational change upon s CD4 binding. To investigate the conformational flexibility of gp120, we generated two forms of mutated gp120 amenable for NMR studies: one with V1, V2 and V3 omitted (mutgp120core) and the other containing the V3 region [mutgp120core(+V3)]. The TROSY-1H-15N-HSQC spectra of [2H,13C,15N]Arg-labeled and [2H,13C,15N]Ile-labeled unliganded mutgp120core showed many fewer crosspeaks than the expected number, and also many fewer crosspeaks in comparison with the labeled mutgp120core bound to the CD4-mimic peptide, CD4M33. This finding suggests that in the unliganded form, mutgp120core shows considerable flexibility and motions on the millisecond time scale. In contrast, most of the expected crosspeaks were observed for the unliganded mutgp120core(+V3), and only a few changes in chemical shift were observed upon CD4M33 binding. These results indicate that mutgp120core(+V3) does not show any significant conformational flexibility in its unliganded form and does not undergo any significant conformational change upon CD4M33 binding, underlining the importance of V3 in stabilizing the gp120core conformation. [ABSTRACT FROM AUTHOR]