Efficient induction and expansion of human alloantigen-specific CD8 regulatory T cells from naive precursors by CD40-activated B cells

Characteristics and functions of memory regulatory T cells in normal pregnancy cycle and pregnancy complications

Regulatory T cells (Tregs) are activated and expanded after exposure to fetal-specific (paternal) antigens. A proportion of Tregs differentiate into memory Tregs (mTregs), exhibiting immune memory function and exerting more potent immunosuppression than naive Tregs (nTregs). However, it is unclear how mTregs are regulated during normal and pathological pregnancies (e.g., gestational diabetes mellitus (GDM) and preeclampsia (PE)). In this study, PD-1, HLA-G, and HLA-DR expressions on memory CD4+ T cells, naive CD4+ T cells, Tregs, mTregs, and nTregs in healthy non-pregnant women (n=20), healthy first (n=20), second (n=20), and third-trimester women (n=20), postpartum women (n=20), GDM (n=20), and PE patients (n=20) were analyzed. The proportion of mTregs out of Tregs was increased (P<0.05) in the first trimester compared with that in non-pregnancy and reduced in the second and third trimesters. The proportions of PD-1+ Tregs and mTregs were significantly increased during the first trimester compared to those of non-pregnancy (P<0.01), reached their maximum in the second trimester. Moreover, the proportions of HLA-G+ memory CD4+ T cells, Tregs, and mTregs were increased in the first and second trimesters (P<0.01), reached their maximum in the third trimester. GDM patients were characterized by significantly lower percentages of PD-1+ and HLA-G+ mTregs (P<0.01), while PE patients were characterized by significantly lower percentages of HLA-G+ mTregs (P<0.01), compared with the healthy third-trimester women. In general, as demonstrated by this study, mTregs increase in number and enhance maternal-fetal immunoregulation during pregnancy, and their dysfunction can result in pregnancy complications such as GMD or PE.

Cytolytic CD4+ and CD8+ Regulatory T-Cells and Implications for Developing Immunotherapies to Combat Graft-Versus-Host Disease

Regulatory T-cells (Treg) are critical for the maintenance of immune homeostasis and tolerance induction. While the immunosuppressive mechanisms of Treg have been extensively investigated for decades, the mechanisms responsible for Treg cytotoxicity and their therapeutic potential in regulating immune responses have been incompletely explored and exploited. Conventional cytotoxic T effector cells (Teffs) are known to be important for adaptive immune responses, particularly in the settings of viral infections and cancer. CD4+ and CD8+ Treg subsets may also share similar cytotoxic properties with conventional Teffs. Cytotoxic effector Treg (cyTreg) are a heterogeneous population in the periphery that retain the capacity to suppress T-cell proliferation and activation, induce cellular apoptosis, and migrate to tissues to ensure immune homeostasis. The latter can occur through several cytolytic mechanisms, including the Granzyme/Perforin and Fas/FasL signaling pathways. This review focuses on the current knowledge and recent advances in our understanding of cyTreg and their potential application in the treatment of human disease, particularly Graft-versus-Host Disease (GVHD).

Prognostic significance of natural killer cell-associated markers in gastric cancer: quantitative analysis using multiplex immunohistochemistry

BACKGROUND

Natural killer (NK) cells mediate the anti-tumoral immune response as an important component of innate immunity. The aim of this study was to investigate the prognostic significance and functional implication of NK cell-associated surface receptors in gastric cancer (GC) by using multiplex immunohistochemistry (mIHC).

METHODS

We performed an mIHC on tissue microarray slides, including 55 GC tissue samples. A total of 11 antibodies including CD57, NKG2A, CD16, HLA-E, CD3, CD20, CD45, CD68, CK, SMA, and ki-67 were used. CD45 + CD3-CD57 + cells were considered as CD57 + NK cells.

RESULTS

Among CD45 + immune cells, the proportion of CD57 + NK cell was the lowest (3.8%), whereas that of CD57 + and CD57- T cells (65.5%) was the highest, followed by macrophages (25.4%), and B cells (5.3%). CD57 + NK cells constituted 20% of CD45 + CD57 + immune cells while the remaining 80% were CD57 + T cells. The expression of HLA-E in tumor cells correlated with that in tumoral T cells, B cells, and macrophages, but not CD57 + NK cells. The higher density of tumoral CD57 + NK cells and tumoral CD57 + NKG2A + NK cells was associated with inferior survival.

CONCLUSIONS

Although the number of CD57 + NK cells was lower than that of other immune cells, CD57 + NK cells and CD57 + NKG2A + NK cells were significantly associated with poor outcomes, suggesting that NK cell subsets play a critical role in GC progression. NK cells and their inhibitory receptor, NKG2A, may be potential targets in GC.

Newly Found Peacekeeper: Potential of CD8+ Tregs for Graft-Versus-Host Disease

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the most effective and potentially curative treatment for a variety of hematologic malignancies. However, graft-versus-host disease (GVHD) is a major obstacle that limits wide application of allo-HSCT, despite the development of prophylactic strategies. Owing to experimental and clinical advances in the field, GVHD is characterized by disruption of the balance between effector and regulatory immune cells, resulting in higher inflammatory cytokine levels. A reduction in regulatory T cells (Tregs) has been associated with limiting recalibration of inflammatory overaction and maintaining immune tolerance. Moreover, accumulating evidence suggests that immunoregulation may be useful for preventing GVHD. As opposed to CD4⁺ Tregs, the CD8⁺ Tregs population, which constitutes an important proportion of all Tregs, efficiently attenuates GVHD while sparing graft-versus-leukemic (GVL) effects. CD8⁺ Tregs may provide another form of cellular therapy for preventing GVHD and preserving GVL effects, and understanding the underlying mechanisms that different from those of CD4⁺ Tregs is significant. In this review, we summarize preclinical experiments that have demonstrated the role of CD8⁺ Tregs during GVHD and attempted to obtain optimized CD8⁺ Tregs. Notably, although optimized CD8⁺ Tregs have obvious advantages, more exploration is needed to determine how to apply them in the clinic.

Porcine-Stimulated Human Tr1 Cells Showed Enhanced Suppression in Xenoantigen Stimulation Response

Type 1 regulatory T (Tr1) cells play a fundamental role in maintaining and inducing immune tolerance. Our preliminary study demonstrated that an interleukin- (IL-) 10-mediated pathway is a possible regulatory mechanism underlying the xenoantigen-specific human Treg enhanced suppressive capacity. Here, we developed a feasible protocol for expanding IL-10-induced xenoantigen-specific human Tr1 cells in vitro which would be more efficient in transplantation immunotherapy efficiency. In this study, xenoantigen-specific Tr1 cells are generated from human naive CD4+ T cells expanded for two subsequent xenoantigen-stimulation cycles with recombinant human IL-10. The phenotype and suppressive capacity of xenoantigen-stimulated Tr1 cells are assessed, and the mechanism of their suppression is studied. Tr1 cells can be induced by porcine xenoantigen stimulation combined with IL-10, IL-2, and IL-15, displaying an increased expression of CD49b, CTLA-4, and LAG-3 without expressing Foxp3 which also showed an effector memory Treg phenotype and expressed high levels of CD39. After xenoantigen stimulation, the IL-10 and IL-5 gene expression in Tr1 cells increased, secreting more IL-10, and xenoantigen-stimulated Tr1 cells changed their T cell receptor (TCR) Vβ repertoire, increasing the expression of TCR Vβ2, TCR Vβ9, and TCR Vβ13. In a pig to human mixed lymphocyte reaction (MLR), xenoantigen-stimulated Tr1 cells displayed enhanced suppressive capacity via CD39 in a dose-dependent manner. Moreover, IL-5 could affect the proliferation of xenoantigen-specific Tr1 cells, but not their phenotypes' expression. This study provides a theory and feasible method for immune tolerance induction in clinical xenotransplantation.

Antigen Specific Regulatory T Cells in Kidney Transplantation and Other Tolerance Settings

Kidney transplantation is the most common solid organ transplant and the best current therapy for end-stage kidney failure. However, with standard immunosuppression, most transplants develop chronic dysfunction or fail, much of which is due to chronic immune injury. Tregs are a subset of T cells involved in limiting immune activation and preventing autoimmune disease. These cells offer the potential to provide tolerance or to allow reduction in immunosuppression in kidney transplants. The importance of Tregs in kidney transplantation has been shown in a number of seminal mouse and animal studies, including those with T cell receptors (TCRs) transgenic Tregs (TCR-Tregs) or Chimeric Antigen Receptor (CAR) Tregs (CAR-Tregs) showing that specificity increases the potency of Treg function. Here we outline the animal and human studies and clinical trials directed at using Tregs in kidney transplantation and other tolerance settings and the various modifications to enhance allo-specific Treg function in vivo and in vitro.

The role of CD8+ T-cell systemic lupus erythematosus pathogenesis: an update

PURPOSE OF REVIEW

Systemic lupus erythematosus (SLE) is a serious autoimmune disease with a wide range of organ involvement. In addition to aberrant B-cell responses leading to autoantibody production, T-cell abnormalities are important in the induction of autoimmunity and the ensuing downstream organ damage. In this article, we present an update on how subsets of CD8+ T cells contribute to SLE pathogenesis.

RECENT FINDINGS

Reduced cytolytic function of CD8+ T cells not only promotes systemic autoimmunity but also accounts for the increased risk of infections. Additional information suggests that effector functions of tissue CD8+ T cells contribute to organ damage. The phenotypic changes in tissue CD8+ T cells likely arise from exposure to tissue microenvironment and crosstalk with tissue resident cells. Research on pathogenic IL-17-producing double negative T cells also suggests their origin from autoreactive CD8+ T cells, which also contribute to the induction and maintenance of systemic autoimmunity.

SUMMARY

Reduced CD8+ T-cell effector function illustrates their role in peripheral tolerance in the control of autoimmunity and to the increased risk of infections. Inflammatory cytokine producing double negative T cells and functional defects of regulatory CD8+ T cell both contribute to SLE pathogenesis. Further in depth research on these phenotypic changes are warranted for the development of new therapeutics for people with SLE.

Super-Treg: Toward a New Era of Adoptive Treg Therapy Enabled by Genetic Modifications

Regulatory Tcells (Treg) are essential components of peripheral immune homeostasis. Adoptive Treg cell therapy has shown efficacy in a variety of immune-mediated diseases in preclinical studies and is now moving from phase I/IIa to larger phase II studies aiming to demonstrate efficacy. However, hurdles such as in vivo stability and efficacy remain to be addressed. Nevertheless, preclinical models have shown that Treg function and specificity can be increased by pharmacological substances or gene modifications, and even that conventional T cells can be converted to Treg potentially providing new sources of Treg and facilitating Treg cell therapy. The exponential growth in genetic engineering techniques and their application to T cells coupled to a large body of knowledge on Treg open numerous opportunities to generate Treg with "superpowers". This review summarizes the genetic engineering techniques available and their applications for the next-generation of Super-Treg with increased function, stability, redirected specificity and survival.

Immunosuppressive Amino-Acid Catabolizing Enzymes in Multiple Sclerosis

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease that affects the central nervous system. Although the pathogenesis of MS is not yet fully elucidated, several evidences suggest that autoimmune processes mediated by Th1, Th17, and B cells play an important role in the development of the disease. Similar to other cells, immune cells need continuous access to amino acids (AA) in order to maintain basal metabolism and maintain vitality. When immune cells are activated by inflammation or antigenic signals, their demand for AA increases rapidly. Although AA deprivation itself may weaken the immune response under certain conditions, cells also have AA sensitive pathways that can activate intense alterations in cell metabolism based on changes in AA levels. Several data indicate that cells expressing enzymes that can degrade AA can regulate the functions of antigen-presenting cells and lymphocytes, revealing that the AA pathways are essential for controlling the function, and survival of immune cells, as well as immune cell gene expression. Basal AA catabolism may contribute to immune homeostasis and prevent autoimmunity, while increased AA catalytic activity may enhance immune suppression. In addition, there is increasing evidence that some downstream AA metabolites are important biological mediators of autoimmune response regulation. Two of the most important AA that modulate the immune response are L-Tryptophan (Trp) and L-Arginine (Arg). Tryptophan is catabolized through 2,3-dioxygenase (TDO) and indoleamine 2,3-dioxygenase (IDO) 1 and IDO2 enzymes, while three other enzymes catabolize Arg: inducible nitric oxide synthetase (iNOS), and two arginase isoforms (ARG1, ARG2). Genes encoding IDO, iNOS and ARG are induced by inflammatory cues such as cytokines, a key feature that distinguishes them from enzymes that catabolize other AA. Evidence suggests that AA catabolism is decreased in MS patients and that this decrease has functional consequences, increasing pro-inflammatory cytokines and decreasing Treg cell numbers. These effects are mediated by at least two distinct pathways involving serine/threonine kinases: the general control nonderepressible 2 kinase (GCN2K) pathway; and the mammalian target of rapamycin (mTOR) pathway. Similarly, IDO1-deficient mice showed exacerbation of experimental autoimmune encephalomyelitis (EAE), increased Th1 and Th17 cells, and decreased Treg cells. On the contrary, the administration of downstream Trp metabolite 3-HAA, inhibits Th1/Th17 effector cells and promotes Treg response by up-regulating TGF-β production by dendritic cells, thereby improving EAE. Collectively, these observations stand out the significance of AA catabolism in the regulation of the immune responses in MS patients. The molecules related to these pathways deserve further exploration as potential new therapeutic targets in MS.

CD8+CD122+PD-1+ Tregs Synergize With Costimulatory Blockade of CD40/CD154, but Not B7/CD28, to Prolong Murine Allograft Survival

A transplanted organ is always rejected in the absence of any immunosuppressive treatment due to vigorous alloimmunity. However, continuously global immunosuppression with a conventional immunosuppressant may result in severe side effects, including nephrotoxicity, tumors and infections. Tregs have been widely used to inhibit allograft rejection, especially in animal models. However, it's well accepted that administration of Tregs alone is not satisfactory in immune-competent wild-type animals. Therefore, it's imperative to promote Treg therapies under the cover of other approaches, including costimulatory blockade. In the present study, we demonstrated that administration of in vitro-expanded CD8⁺CD122⁺PD-1⁺ Tregs synergized with costimulatory blockade of CD40/CD154, but not B7/CD28, to prolong skin allograft survival in wild-type mice and to reduce cellular infiltration in skin allografts as well. Treg treatment and blockade of CD40/CD154, but not B7/CD28, also exhibited an additive effect on suppression of T cell proliferation in vitro and pro-inflammatory cytokine expression in skin allografts. Importantly, blocking B7/CD28, but not CD40/CD154, costimulation decreased the number of transferred CD8⁺CD122⁺PD-1⁺ Tregs and their expression of IL-10 in recipient mice. Furthermore, it's B7/CD28, but not CD40/CD154, costimulatory blockade that dramatically reduced IL-10 production by CD8⁺CD122⁺PD-1⁺ Tregs in vitro, suggesting that B7/CD28, but not CD40/CD154, costimulation is critical for their production of IL-10. Indeed, infusion of IL-10-deficient CD8⁺CD122⁺PD-1⁺ Tregs failed to synergize with anti-CD154 Ab treatment to further prolong allograft survival. Our data may explain why blocking B7/CD28 costimulatory pathway does not boost IL-10-dependent Treg suppression of alloimmunity. Thus, these findings could be implicated in clinical organ transplantation.

B Cell-Based Cancer Immunotherapy

B cells are not only producers of antibodies, but also contribute to immune regulation or act as potent antigen-presenting cells. The potential of B cells for cellular therapy is still largely underestimated, despite their multiple diverse effector functions. The CD40L/CD40 signaling pathway is the most potent activator of antigen presentation capacity in B lymphocytes. CD40-activated B cells are potent antigen-presenting cells that induce specific T-cell responses in vitro and in vivo. In preclinical cancer models in mice and dogs, CD40-activated B cell-based cancer immunotherapy was able to induce effective antitumor immunity. So far, there have been only few early-stage clinical studies involving B cell-based cancer vaccines. These trials indicate that B cell-based immunotherapy is generally safe and associated with little toxicity. Furthermore, these studies suggest that B-cell immunotherapy can elicit antitumor T-cell responses. Alongside the recent advances in cellular therapies in general, major obstacles for generation of good manufacturing practice-manufactured B-cell immunotherapies have been overcome. Thus, a first clinical trial involving CD40-activated B cells might be in reach.

Adoptive transfer of xenoantigen‑stimulated T cell receptor Vβ‑restricted human regulatory T cells prevents porcine islet xenograft rejection in humanized mice

Polyclonal expansion of human regulatory T cells (Tregs) prevents xenogeneic rejection by suppressing effector T cell responses in vitro and in vivo. However, a major limitation to using polyclonally expanded Tregs is that they may cause pan‑immunosuppressive effects. The present study was conducted to compare the ability of ex vivo expanded human xenoantigen‑stimulated Tregs (Xeno‑Treg) and polyclonal Tregs (Poly‑Treg) to protect islet xenografts from rejection in NOD‑SCID interleukin (IL)‑2 receptor (IL2r)γ‑/‑ mice. Human cluster of differentiation (CD)4+CD25+CD127lo Tregs, expanded either by stimulating with porcine peripheral blood mononuclear cells (PBMCs) or anti‑CD3/CD28 beads, were characterized by immune cell phenotyping, T cell receptor (TCR) Vβ CDR3 spectratyping and performing suppressive activity assays in vitro. The efficiency of adoptively transferred ex vivo human Tregs was evaluated in vivo using neonatal porcine islet cell clusters (NICC) transplanted into NOD‑SCID IL‑2rγ‑/‑ mice, which received human PBMCs with or without Xeno‑Treg or Poly‑Treg. Xeno‑Treg, which expressed increased levels of human leukocyte antigen‑DR and secreted higher levels of IL‑10, demonstrated enhanced suppressive capacity in a pig‑human mixed lymphocyte reaction. Spectratypes of TCR Vβ4, Vβ10, Vβ18 and Vβ20 in Xeno‑Treg showed restriction and expanded clones at sizes of 205, 441, 332 and 196 respectively, compared to those of Poly‑Treg. Reconstitution of mice with human PBMCs and Poly‑Treg resulted in NICC xenograft rejection at 63 days. Adoptive transfer with human PBMCs and Xeno‑Treg prolonged islet xenograft survival beyond 84 days, with grafts containing intact insulin‑secreting cells surrounded by a small number of human CD45+ cells. This study demonstrated that adoptive transfer of ex vivo expanded human Xeno‑Treg may potently prevent islet xenograft rejection in humanized NOD‑SCID IL2rγ‑/‑ mice compared with Poly‑Treg. These findings suggested that adoptive Treg therapy may be used for immunomodulation in islet xenotransplantation by minimizing systemic immunosuppression.

Functionalization-dependent effects of cellulose nanofibrils on tolerogenic mechanisms of human dendritic cells

Background

Cellulose nanofibrils (CNF) are attractive nanomaterials for various biomedical applications due to their excellent biocompatibility and biomimetic properties. However, their immunoregulatory properties are insufficiently investigated, especially in relation to their functionalization, which could cause problems during their clinical application.

Methods

Using a model of human dendritic cells (DC), which have a central role in the regulation of immune response, we investigated how differentially functionalized CNF, ie, native (n) CNF, 2,2,6,6-tetramethylpiperidine 1-oxyl radical-oxidized (c) CNF, and 3-aminopropylphosphoric acid-functionalized (APAc) CNF, affect DC properties, their viability, morphology, differentiation and maturation potential, and the capacity to regulate T cell-mediated immune response.

Results

Nontoxic doses of APAcCNF displayed the strongest inhibitory effects on DC differentiation, maturation, and T helper (Th) 1 and Th17 polarization capacity, followed by cCNF and nCNF, respectively. These results correlated with a specific pattern of regulatory cytokines production by APAcCNF-DC and their increased capacity to induce suppressive CD8⁺CD25⁺IL-10⁺ regulatory T cells in immunoglobulin-like transcript (ILT)-3- and ILT-4- dependent manner. In contrast, nCNF-DC induced predominantly suppressive CD4⁺CD25^hiFoxP3^hi regulatory T cells in indolamine 2,3-dioxygenase-1-dependent manner. Different tolerogenic properties of CNF correlated with their size and APA functionalization, as well as with different expression of CD209 and actin bundles at the place of contact with CNF.

Conclusion

The capacity to induce different types of DC-mediated tolerogenic immune responses by functionalized CNF opens new perspectives for their application as well-tolerated nanomaterials in tissue engineering and novel platforms for the therapy of inflammatory T cell-mediated pathologies.

Ex Vivo Expanded Human Non-Cytotoxic CD8+CD45RClow/- Tregs Efficiently Delay Skin Graft Rejection and GVHD in Humanized Mice

Both CD4⁺ and CD8⁺ Tregs play a critical role in the control of immune responses and immune tolerance; however, our understanding of CD8⁺ Tregs is limited while they are particularly promising for therapeutic application. We report here existence of highly suppressive human CD8⁺CD45RC^low/− Tregs expressing Foxp3 and producing IFNγ, IL-10, IL-34, and TGFβ to mediate their suppressive activity. We demonstrate that total CD8⁺CD45RC^low/− Tregs can be efficiently expanded in the presence of anti-CD3/28 mAbs, high-dose IL-2 and IL-15 and that such expanded Tregs efficiently delay GVHD and human skin transplantation rejection in immune humanized mice. Robustly expanded CD8⁺ Tregs displayed a specific gene signature, upregulated cytokines and expansion in the presence of rapamycin greatly improved proliferation and suppression. We show that CD8⁺CD45RC^low/− Tregs are equivalent to canonical CD4⁺CD25^highCD127^low/− Tregs for suppression of allogeneic immune responses in vitro. Altogether, our results open new perspectives to tolerogenic strategies in human solid organ transplantation and GVHD.

Co-expression of CD40L with CD70 or OX40L increases B-cell viability and antitumor efficacy

Activated B-cells are a promising alternative source of antigen-presenting cells. They can generally be obtained in sufficient numbers for clinical use, but in most instances produce weak immune responses and therapeutic effects that are suboptimal for use in therapeutic cancer vaccines. To improve the immunogenic potency and therapeutic efficacy of B-cell-based vaccines, ex vivo-activated B-cells were transduced with recombinant lentiviruses in order to express additional costimulatory ligands—CD40L, CD70, OX40L, or 4-1BBL—either individually or in pairs (CD70/CD40L, OX40L/CD40L, or 4-1BBL/CD40L). We observed that the expression of CD40L molecules on B-cells was crucial for T-cell priming and activation. Administration of B-cells co-expressing CD40L with the other costimulatory ligands provided substantial antigen-specific CD8 T-cell responses capable of provoking in vivo proliferation and potent cytolytic activities. Notably, expression of CD40L augmented B-cell viability by inhibiting apoptosis through upregulated expression of the anti-apoptotic molecules BCL2, Bcl-xL and Bax. B-cells co-expressing CD40L with CD70, OX40L, or 4-1BBL induced potent therapeutic antitumor effects in a B16 melanoma model. Moreover, the combination of genetically-modified B-cell vaccines with programmed cell death-1 blockade potentiated the therapeutic efficacy. These results suggest that B-cells endowed with additional costimulatory ligands enable the design of effective vaccination strategies against cancer.

High pathogen burden in childhood promotes the development of unconventional innate-like CD8+ T cells

Cellular and humoral constituents of the immune system differ significantly between children and adults, yet very little is known about the impact of early-life pathogen exposure on this immunologic transition. We examined CD4+ and CD8+ T cell subsets defined by CCR7 and CD45RA expression in two longitudinal pediatric cohorts experiencing divergent levels of pathogen burden. Using multiparameter flow cytometry, along with serological, cytokine, and transcriptomic data, we show that cumulative pathogen burden promotes the development of atypical CD8dim T cells with an innate-like profile (Granzyme Bhi, IFNγlow, TNFαlow, PLFZhi, ID2hi, IKZF2hi) in contrast to age-matched children residing in a low pathogen-exposure area who display a more conventional CD8bright profile (IFNγ+, TNFα+, CCL4+). Furthermore, these unconventional T cells had stunted proliferation, distinct transcriptional programs, and impaired T cell receptor signaling and were enriched in hallmark TNFα, NF-κB, and IL-6 gene signaling pathways, reminiscent of NK cells and type-1 innate lymphoid cells. Our findings suggest that these unconventional CD8dim T cells arise in a very particular immunological context and may provide a deeper understanding of the heterogeneity in human immune responses.

Association between CD40 rs1883832 and immune-related diseases susceptibility: A meta-analysis

Background/objective

It has been reported that CD40 rs1883832 might be associated with immune-related diseases susceptibility. Owing to mixed and inconclusive results, we conducted a meta-analysis of case–control studies to summarize and clarify this association.

Methods/main results

A systematic search of studies on the association between CD40 rs1883832 and immune-related diseases susceptibility was conducted in databases. Odds ratios and 95% confidence intervals were used to pool the effect size. 40 articles were included in our meta-analysis.

Conclusions

CD40 rs1883832 is associated with decreased risk of Graves’ disease, especially in Asian; CD40 rs1883832 is associated with increased risk of multiple sclerosis; CD40 -1C>T (rs1883832) is not associated with the susceptibility of Hashimoto's thyroiditis, systemic sclerosis or Asthma; there is insufficient data to fully confirm the association between CD40 rs1883832 and systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), Behçet's disease (BD), myasthenia gravis (MG), Crohn's disease (CD), ulcerative colitis (UC), Sarcoidosis, Fuch uveitis syndrome (FUS), Vogt-Koyanagi-Harada syndrome (VKH), Kawasaki disease (KD), giant cell arteritis (GCA) or Immune thrombocytopenia (ITP).

Cell Therapy in Kidney Transplantation: Focus on Regulatory T Cells

Renal transplantation is the renal replacement modality of choice for suitable candidates with advanced CKD or ESRD. Prevention of rejection, however, requires treatment with nonspecific pharmacologic immunosuppressants that carry both systemic and nephrologic toxicities. Use of a patient's own suppressive regulatory T cells (Tregs) is an attractive biologic approach to reduce this burden. Here, we review the immunologic underpinnings of Treg therapy and technical challenges to developing successful cell therapy. These issues include the selection of appropriate Treg subsets, ex vivo Treg expansion approaches, how many Tregs to administer and when, and how to care for patients after Treg administration.

Cell enrichment-free massive ex-vivo expansion of peripheral CD20⁺ B cells via CD40-CD40L signals in non-human primates

Non-human primates (NHPs) are valuable as preclinical resources that bridge the gap between basic science and clinical application. B cells from NHPs have been utilized for the development of B-cell targeted drugs and cell-based therapeutic modalities; however, few studies on the ex-vivo expansion of monkey B cells have been reported. In this study, we developed a highly efficient ex-vivo expansion protocol for monkey B cells resulting in 99% purity without the requirement for prior cell-enrichment procedures. To this end, monkey peripheral blood mononuclear cells (PBMCs) were stimulated for 12 days with cells constitutively expressing monkey CD40L in expansion medium optimized for specific and massive expansion of B cells. The B cells expansion rates obtained were 2-5 times higher than those previously reported in humans, with rates ranging from 7.9 to 16.6 fold increase. Moreover, expanded B cells sustained high expression of co-stimulatory molecules including CD83 and CD86 until day 12 of culture, and the simple application of a brief centrifugation resulted in a CD20(+) B cell purity rate of greater than 99%. Furthermore, small amounts of CD3(+)CD20(+)BT-like cells were generated and CD16 was expressed at moderate levels on expanded B cells. Thus, the establishment of this protocol provides a method to produce quantities of homogeneous, mature B cells in numbers sufficient for the in vitro study of B cell immunity as well as for the development of B cell-diagnostic tools and cell-based therapeutic modalities.

B cells with regulatory properties in transplantation tolerance

Induction of tolerance remains a major goal in transplantation. Indeed, despite potent immunosuppression, chronic rejection is still a real problem in transplantation. The humoral response is an important mediator of chronic rejection, and numerous strategies have been developed to target either B cells or plasma cells. However, the use of anti-CD20 therapy has highlighted the beneficial role of subpopulation of B cells, termed regulatory B cells. These cells have been characterized mainly in mice models of auto-immune diseases but emerging literature suggests their role in graft tolerance in transplantation. Regulatory B cells seem to be induced following inflammation to restrain excessive response. Different phenotypes of regulatory B cells have been described and are functional at various differentiation steps from immature to plasma cells. These cells act by multiple mechanisms such as secretion of immuno-suppressive cytokines interleukin-10 (IL-10) or IL-35, cytotoxicity, expression of inhibitory receptors or by secretion of non-inflammatory antibodies. Better characterization of the development, phenotype and mode of action of these cells seems urgent to develop novel approaches to manipulate the different B cell subsets and the response to the graft in a clinical setting.

Role of Memory T Cells and Perspectives for Intervention in Organ Transplantation

Memory T cells are necessary for protective immunity against invading pathogens, especially under conditions of immunosuppression. However, their presence also threatens transplant survival, making transplantation a great challenge. Significant progress has been achieved in recent years in advancing our understanding of the role that memory T cells play in transplantation. This review focuses on the latest advances in our understanding of the involvement of memory T cells in graft rejection and transplant tolerance and discusses potential strategies for targeting memory T cells in order to minimize allograft rejection and optimize clinical outcomes.

Human monocyte-derived suppressor cells control graft-versus-host disease by inducing regulatory forkhead box protein 3-positive CD8+ T lymphocytes

BACKGROUND

Adoptive transfer of immunosuppressive cells has emerged as a promising strategy for the treatment of immune-mediated disorders. However, only a limited number of such cells can be isolated from in vivo specimens. Therefore efficient ex vivo differentiation and expansion procedures are critically needed to produce a clinically relevant amount of these suppressive cells.

OBJECTIVE

We sought to develop a novel, clinically relevant, and feasible approach to generate ex vivo a subpopulation of human suppressor cells of monocytic origin, referred to as human monocyte-derived suppressive cells (HuMoSCs), which can be used as an efficient therapeutic tool to treat inflammatory disorders.

METHODS

HuMoSCs were generated from human monocytes cultured for 7 days with GM-CSF and IL-6. The immune-regulatory properties of HuMoSCs were investigated in vitro and in vivo. The therapeutic efficacy of HuMoSCs was evaluated by using a graft-versus-host disease (GvHD) model of humanized mice (NOD/SCID/IL-2Rγc(-/-) [NSG] mice).

RESULTS

CD33+ HuMoSCs are highly potent at inhibiting the proliferation and activation of autologous and allogeneic effector T lymphocytes in vitro and in vivo. The suppressive activity of these cells depends on signal transducer and activator of transcription 3 activation. Of therapeutic relevance, HuMoSCs induce long-lasting memory forkhead box protein 3-positive CD8+ regulatory T lymphocytes and significantly reduce GvHD induced with human PBMCs in NSG mice.

CONCLUSION

Ex vivo-generated HuMoSCs inhibit effector T lymphocytes, promote the expansion of immunosuppressive forkhead box protein 3-positive CD8+ regulatory T cells, and can be used as an efficient therapeutic tool to prevent GvHD.

MS risk allele rs1883832T is associated with decreased mRNA expression of CD40

CD40-CD40L interactions mediate T-dependent B cell response and efficient T cell priming. Therefore, genes encoding these molecules are attractive candidates for studies on autoimmune diseases, such as multiple sclerosis (MS), in which activated T and B cells are involved. Thus, we analyzed CD40 and CD40L mRNA expression in whole blood samples from MS patients and controls. Additionally, we examined the effect of three SNPs of CD40 (rs1883832C>T, rs11569343C>G, and rs752118C>T) and two SNPs of CD40L (rs3092923T>C and rs3092952A>G) on their mRNA expression. Our results showed that the rs1883832C>T SNP affects CD40 gene expression. Our analysis revealed that individuals possessing CT and TT genotypes (predisposing to MS) had decreased level of CD40 mRNA in comparison to those with CC. Moreover, we demonstrated the potential role of impaired CD40-CD40L interaction in developing of multiple sclerosis.

Negligible immunogenicity of induced pluripotent stem cells derived from human skin fibroblasts

Human induced pluripotent stem cells (hiPSCs) have potential applications in cell replacement therapy and regenerative medicine. However, limited information is available regarding the immunologic features of iPSCs. In this study, expression of MHC and T cell co-stimulatory molecules in hiPSCs, and the effects on activation, proliferation and cytokine production in allogeneic human peripheral blood mononuclear cells were examined. We found that no-integrate hiPSCs had no MHC-II and T cell co-stimulatory molecules expressions but had moderate level of MHC-I and HLA-G expressions. In contrast to human skin fibroblasts (HSFs) which significantly induced allogeneic T cell activation and proliferation, hiPSCs failed to induce allogeneic CD45⁺ lymphocyte and CD8⁺ T cell activation and proliferation but could induce a low level of allogeneic CD4⁺ T cell proliferation. Unlike HSFs which induced allogeneic lymphocytes to produce high levels of IFN-γ, TNF-α and IL-17, hiPSCs only induced allogeneic lymphocytes to produce IL-2 and IL-10, and promote IL-10-secreting regulatory T cell (Treg) generation. Our study suggests that the integration-free hiPSCs had low or negligible immunogenicity, which may result from their induction of IL-10-secreting Treg.

Novel GMP-compatible protocol employing an allogeneic B cell bank for clonal expansion of allospecific natural regulatory T cells

The adoptive transfer of natural regulatory T cells (nTreg) is a new option to reshape undesired immune reactivity in autoimmunity and transplantation toward "tolerance." The first clinical trials using adoptive transfer of polyclonal nTreg demonstrated safety and hints of efficacy. However, the low frequencies of antigen-specific cells among the pool of polyclonal nTreg and their broad antigen nonspecific suppression are limitations of this approach regarding efficacy and safety. Recently, the isolation and expansion of (allo)antigen-specific nTreg have successfully been achieved by using Treg-specific activation markers but the yield is relatively low. Here, we describe a novel good manufacturing practice (GMP)-compatible expansion protocol of alloantigen-specific nTreg based on the stimulation of nTreg by allogeneic activated B cells. Their functionality and specificity are superior compared to polyclonal nTreg both in vitro and in vivo. Employing an allogeneic B cell bank, designed to cover the majority of HLA types, allows fast GMP-compliant manufacturing for donor-specific nTreg for clinical application in organ and stem cell transplantation. TCR repertoire analyses by next generation sequencing revealed impressive expansion by several log-steps of even very low-abundance alloantigen-specific nTreg clones. This novel method offers a simple approach for expanding antigen-specific nTreg and is characterized by high replicability and easy transferability to full GMP standards.

Role of CD8(+) regulatory T cells in organ transplantation

CD8⁺ T cells are regulatory T cells (Tregs) that suppress both alloimmunity and autoimmunity in many animal models. This class of regulatory cells includes the CD8⁺CD28⁻, CD8⁺CD103⁺, CD8⁺FoxP3⁺ and CD8⁺CD122⁺ subsets. The mechanisms of action of these regulatory cells are not fully understood; however, the secretion of immunosuppressive cytokines, such as interleukin (IL)-4, IL-10 and transforming growth factor beta (TGF-β) as well as the direct killing of target cells via Fas L/Fas and the perforin/granzyme B pathways have been demonstrated in various models. Further studies are necessary to fully understand the mechanisms underlying the suppressive effects of Tregs and to provide experimental support for potential clinical trials. We recently observed that CD8⁺CD122⁺ Tregs more potently suppressed allograft rejection compared to their CD4⁺CD25⁺ counterparts, supporting the hypothesis that CD8⁺ Tregs may represent a new and promising Treg family that can be targeted to prevent allograft rejection in the clinic. In this review, we summarize the progress in the field during the past 7–10 years and discuss CD8⁺ Treg phenotypes, mechanisms of action, and their potential clinical applications; particularly in composite tissue transplants in burn and trauma patients.

Influenza virus-induced lung inflammation was modulated by cigarette smoke exposure in mice

Although smokers have increased susceptibility and severity of seasonal influenza virus infection, there is no report about the risk of 2009 pandemic H1N1 (pdmH1N1) or avian H9N2 (H9N2/G1) virus infection in smokers. In our study, we used mouse model to investigate the effect of cigarette smoke on pdmH1N1 or H9N2 virus infection. Mice were exposed to cigarette smoke for 21 days and then infected with pdmH1N1 or H9N2 virus. Control mice were exposed to air in parallel. We found that cigarette smoke exposure alone significantly upregulated the lung inflammation. Such prior cigarette smoke exposure significantly reduced the disease severity of subsequent pdmH1N1 or H9N2 virus infection. For pdmH1N1 infection, cigarette smoke exposed mice had significantly lower mortality than the control mice, possibly due to the significantly decreased production of inflammatory cytokines and chemokines. Similarly, after H9N2 infection, cigarette smoke exposed mice displayed significantly less weight loss, which might be attributed to lower cytokines and chemokines production, less macrophages, neutrophils, CD4⁺ and CD8⁺ T cells infiltration and reduced lung damage compared to the control mice. To further investigate the underlying mechanism, we used nicotine to mimic the effect of cigarette smoke both in vitro and in vivo. Pre-treating the primary human macrophages with nicotine for 72 h significantly decreased their expression of cytokines and chemokines after pdmH1N1 or H9N2 infection. The mice subcutaneously and continuously treated with nicotine displayed significantly less weight loss and lower inflammatory response than the control mice upon pdmH1N1 or H9N2 infection. Moreover, α7 nicotinic acetylcholine receptor knockout mice had more body weight loss than wild-type mice after cigarette smoke exposure and H9N2 infection. Our study provided the first evidence that the pathogenicity of both pdmH1N1 and H9N2 viruses was alleviated in cigarette smoke exposed mice, which might partially be attributed to the immunosuppressive effect of nicotine.

ICOS regulates the generation and function of human CD4+ Treg in a CTLA-4 dependent manner

Inducible co-stimulator (ICOS) is a member of CD28/Cytotoxic T-lymphocyte Antigen-4 (CTLA-4) family and broadly expressed in activated CD4(+) T cells and induced regulatory CD4(+) T cells (CD4(+) iTreg). ICOS-related signal pathway could be activated by the interaction between ICOS and its ligand (ICOSL). In our previous work, we established a cost-effective system to generate a novel human allo-antigen specific CD4(hi) Treg by co-culturing their naïve precursors with allogeneic CD40-activated B cells in vitro. Here we investigate the role of ICOS in the generation and function of CD4(hi) Treg by interrupting ICOS-ICOSL interaction with ICOS-Ig. It is found that blockade of ICOS-ICOSL interaction impairs the induction and expansion of CD4(hi) Treg induced by allogeneic CD40-activated B cells. More importantly, CD4(hi) Treg induced with the addition of ICOS-Ig exhibits decreased suppressive capacity on alloantigen-specific responses. Dysfunction of CD4(hi) Treg induced with ICOS-Ig is accompanied with its decreased exocytosis and surface CTLA-4 expression. Through inhibiting endocytosis with E64 and pepstatin A, surface CTLA-4 expression and suppressive functions of induced CD4(hi) Treg could be partly reversed. Conclusively, our results demonstrate the beneficial role of ICOS-ICOSL signal pathway in the generation and function of CD4(hi) Treg and uncover a novel relationship between ICOS and CTLA-4.

Retinoic acid-producing, ex-vivo-generated human tolerogenic dendritic cells induce the proliferation of immunosuppressive B lymphocytes

While much is known about tolerogenic dendritic cell effects on forkhead box protein 3 (FoxP3)⁺ regulatory T cells, virtually nothing is known about their effects on another arm of immunoregulation that is mediated by a subpopulation of immunosuppressive B cells. These cells suppress rheumatoid arthritis, lupus and inflammatory bowel disease in mice, and functional defects have been reported in human lupus. We show that co-stimulation-impaired tolerogenic dendritic cells that prevent and reverse type 1 diabetes mellitus induce the proliferation of human immunosuppressive B cells in vitro. We also show that the suppressive properties of these B cells concentrate inside the CD19⁺ CD24⁺ B cell population and more specifically inside the CD19⁺ CD24⁺ CD38⁺ regulatory B cell population. We discovered that B cell conversion into suppressive cells in vitro is partially dependent on dendritic cell production of retinoic acid and also that CD19⁺ CD24⁺ CD38⁺ B regulatory cells express retinoic acid receptors. Taken together, our data suggest a model whereby part of the immunosuppressive properties of human tolerogenic dendritic cells could be mediated by retinoic acid which, in addition to its known role in favouring T cell differentiation to FoxP3⁺ regulatory T cells, acts to convert B cells into immunosuppressive cells.

Human CD8+ regulatory T cells inhibit GVHD and preserve general immunity in humanized mice

Graft-versus-host disease (GVHD) is a lethal complication of allogeneic bone marrow transplantation (BMT). Immunosuppressive agents are currently used to control GVHD but may cause general immune suppression and limit the effectiveness of BMT. Adoptive transfer of regulatory T cells (T(regs)) can prevent GVHD in rodents, suggesting a therapeutic potential of T(regs) for GVHD in humans. However, the clinical application of T(reg)-based therapy is hampered by the low frequency of human T(regs) and the lack of a reliable model to test their therapeutic effects in vivo. Recently, we successfully generated human alloantigen-specific CD8(hi) T(regs) in a large scale from antigenically naïve precursors ex vivo using allogeneic CD40-activated B cells as stimulators. We report a human allogeneic GVHD model established in humanized mice to mimic GVHD after BMT in humans. We demonstrate that ex vivo-induced CD8(hi) T(regs) controlled GVHD in an allospecific manner by reducing alloreactive T cell proliferation as well as decreasing inflammatory cytokine and chemokine secretion within target organs through a CTLA-4-dependent mechanism in humanized mice. These CD8(hi) T(regs) induced long-term tolerance effectively without compromising general immunity and graft-versus-tumor activity. Our results support testing of human CD8(hi) T(regs) in GVHD in clinical trials.

Dendritic and T cell response to influenza is normal in the patients with X-linked agammaglobulinemia

Introduction

Influenza virus is a potential cause of severe disease in the immunocompromised. X-linked agammaglobulinemia (XLA) is a primary immunodeficiency characterized by the lack of immunoglobulin, B cells, and plasma cells, secondary to mutation in Bruton’s tyrosine kinase (Btk) gene. Btk is expressed in both B and dendritic cells (DC). However, little is known about the immune response of DC and T cells to influenza virus in XLA patients.

Methods

The in vitro maturation and antigen presenting function of monocyte-derived immature DC (imDC) from 12 XLA patients and 23 age-matched normal controls in response to influenza virus were examined. Influenza virus-specific CD4 and CD8 T cell responses in the patients and controls were further determined after administration of inactivated trivalent influenza vaccine.

Results

imDC from XLA patients had normal maturation based on major histocompatibility complex (MHC)-I, MHC-II, CD83 and CD86 expression, and interferon (IFN)-α and interleukin-12 production upon influenza virus stimulation. They also had a normal capacity to induce allogeneic T cell proliferation in response to influenza virus. TIV was well tolerated in XLA patients. Influenza virus-specific CD4⁺IFN-γ⁺ and CD8⁺ IFN-γ⁺ T cells and HLA-A2/M1_58–66-tetramer⁺ CTLs could be induced by TIV in XLA patients, and the levels and duration of maintaining these virus-specific cells in XLA patients are comparable to that in normal controls.

Conclusion

We demonstrated for the first time that XLA patients have fully competent DC and T cell immune responses to influenza virus. TIV is safe and could be an option for providing T cell-mediated protection against influenza virus infection in XLA patients.

Phenotypic and functional characterization of human γδ T-cell subsets in response to influenza A viruses

Like αβ T cells, human γδ T cells also have different subsets with distinct characteristics. Whether human Vγ9Vδ2 T cells have functionally different subsets in response to influenza A (fluA) viruses remains unknown. In this study, we show for the first time that both central (CD45RA(-)CD27(+)) and effector (CD45RA(-)CD27(-)) memory Vγ9Vδ2 T cells have similar levels of immediate interferon (IFN) γ and cytotoxic responses to human and avian fluA virus-infected cells. In contrast, CD56(+) Vγ9Vδ2 T cells have significantly higher cytotoxicity against fluA virus-infected cells compared with their CD56(-) counterparts, whereas both subsets have similar IFN-γ responses. We further demonstrate that the CD16-dependent degranulation pathway, but not antibody-dependent cell-mediated cytotoxicity, contribute to the superior cytotoxicity of CD56(+) Vγ9Vδ2 T cells. Our study provides further evidence for the phenotypic and functional characterization of human Vγ9Vδ2 T-cell subsets during fluA virus infection and may help improve the γδ T-cell-based immunotherapy for viral infection.

A CD40 single-nucleotide polymorphism affects the lymphocyte profiles in the bronchoalveolar lavage of Japanese patients with sarcoidosis

CD40 plays a critical role in adaptive immunity, and alveolar macrophages in patients with sarcoidosis express higher levels of CD40. This study investigated the association of rs1883832, a functional single-nucleotide polymorphism in the CD40 gene with susceptibility to sarcoidosis and phenotypes of sarcoidosis. Genotyping of rs1883832 in 175 Japanese patients with sarcoidosis and 150 age- and sex-matched controls revealed no significant difference between the genotypes of the patient and control groups (CC/CT/TT, 32.8/52.0/14.7% in the patients; 37.3/48.0/14.7% in the controls, P = 0.66; allele C, 59.1% in the patients, 61.3% in the controls, P = 0.57). T-cell and CD4+ cell counts in the bronchoalveolar lavage fluid were significantly higher in the TT genotype group than in the CC and CT genotype group.

Multiple mechanisms of immune suppression by B lymphocytes

Suppression of the immune system after the resolution of infection or inflammation is an important process that limits immune-mediated pathogenesis and autoimmunity. Several mechanisms of immune suppression have received a great deal of attention in the past three decades. These include mechanisms related to suppressive cytokines, interleukin (IL)-10 and transforming growth factor (TGF)-β, produced by regulatory cells, and mechanisms related to apoptosis mediated by death ligands, Fas ligand (FasL) and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), expressed by killer or cytotoxic cells. Despite many lines of evidence supporting an important role for B lymphocytes as both regulatory and killer cells in many inflammatory settings, relatively little attention has been given to understanding the biology of these cells, their relative importance or their usefulness as therapeutic targets. This review is intended to give an overview of the major mechanisms of immunosuppression used by B lymphocytes during both normal and inflammatory contexts. The more recent discoveries of expression of granzyme B, programmed death 1 ligand 2 (PD-L2) and regulatory antibody production by B cells as well as the interactions of regulatory and killer B cells with regulatory T cells, natural killer T (NKT) cells and other cell populations are discussed. In addition, new evidence on the basis of independent characterizations of regulatory and killer CD5(+) B cells point toward the concept of a multipotent suppressor B cell with seemingly high therapeutic potential.

CD40 C/T-1 polymorphism plays different roles in Graves' disease and Hashimoto's thyroiditis: a meta-analysis

CD40 plays a pathogenic role in various autoimmune diseases. However, studies investigating the association between CD40 C/T-1 polymorphism and autoimmune thyroid diseases risk have reported conflicting results and their relative population effect remains unclear; therefore, a meta-analysis was conducted. The data for this meta-analysis included 14 (4214 cases and 3851 controls) and 4 studies (623 cases and 774 controls) for the association of the CD40 C/T-1 polymorphism with Graves' disease (GD) and Hashimoto's thyroiditis (HT), respectively. Results suggested significant association for CD40 C/T-1 polymorphism (odds ratio 1.267 per C allele, p = 0.000) with GD but without HT. The individuals who carried the C/C or C/T genotype have significantly increased GD risk compared with those who carried T/T genotype (C/C vs. T/T: OR = 1.596, 95% CI, 1.256~2.028; C/T vs. T/T: OR = 1.210, 95% CI, 1.032~1.419; dominant model: OR = 1.366, 95% CI, 1.175~1.587; recessive model: OR = 1.322, 95% CI, 1.147~1.523), while no association was observed in HT. When stratified by ethnicity, the significant association between polymorphism and GD risk of Caucasians was found only in recessive models; but that of Asians was found in all models. In the subgroup analysis of study design, we found thyroid antibody status should be ascertained in controls and euthyroidism subjects with higher levels of thyroid antibody should be excluded from control and included into HT to avoid bias. Our meta-analysis showed that CD40 C/T-1 polymorphism plays different roles in GD and HT. Further studies will be needed to confirm our findings.

Common gamma chain cytokines promote rapid in vitro expansion of allo-specific human CD8+ suppressor T cells

Human CD8⁺ regulatory T cells, particularly the CD8⁺CD28⁻ T suppressor cells, have emerged as an important modulator of alloimmunity. Understanding the conditions under which these cells are induced and/or expanded would greatly facilitate their application in future clinical trials. In the current study, we develop a novel strategy that combines common gamma chain (γc) cytokines IL-2, IL-7 and IL-15 and donor antigen presenting cells (APCs) to stimulate full HLA-mismatched allogeneic human CD8⁺ T cells which results in significant expansions of donor-specific CD8⁺CD28⁻ T suppressor cells in vitro. The expanded CD8⁺CD28⁻ T cells exhibit increased expressions of CTLA-4, FoxP3, and CD25, while down-regulate expressions of CD56, CD57, CD127, and perforin. Furthermore, these cells suppress proliferation of CD4⁺ T cells in a contact-dependent and cytokine-independent manner. Interestingly, the specificity of suppression is restricted by the donor HLA class I antigens but promiscuous to HLA class II antigens, providing a potential mechanism for linked suppression. Taken together, our results demonstrate a novel role for common γc cytokines in combination with donor APCs in the expansion of donor-specific CD8⁺CD28⁻ T suppressor cells, and represent a robust strategy for in vitro generation of such cells for adoptive cellular immunotherapy in transplantation.

Experimental models of B cell tolerance in transplantation

The use of conventional immunosuppression has successfully improved short-term allograft survival, however, long-term allograft survival has remained static and is complicated by serious side effects secondary to the long-term use of immunosuppressive agents. Immunological tolerance is the ultimate goal of organ transplantation, however it is an infrequent event in humans. Accordingly, over the past several decades, there has been a push to fully understand both the cellular and molecular mechanisms that play a role in the induction and maintenance of tolerance, with recent data implicating B cells and donor specific alloantibody as a barrier to and potential mediator of allograft tolerance. The study of B cells and alloantibody in transplant tolerance has evolved over recent years from using rodent models to non-human primate models. This review will discuss the role of B cells and alloantibody as antagonists and facilitators of transplantation tolerance, and highlight the experimental models developed for elucidating the mechanisms of B cell tolerance to alloantigen.

Successive influenza virus infection and Streptococcus pneumoniae stimulation alter human dendritic cell function

BACKGROUND

Influenza virus is a major cause of respiratory disease worldwide and Streptococcus pneumoniae infection associated with influenza often leads to severe complications. Dendritic cells are key antigen presenting cells but its role in such co-infection is unclear.

METHODS

In this study, human monocyte derived-dentritic cells were either concurrently or successively challenged with the combination of live influenza virus and heat killed pneumococcus to mimic the viral pneumococcal infection. Dendritic cell viability, phenotypic maturation and cytokine production were then examined.

RESULTS

The challenge of influenza virus and pneumococcus altered dendritic cell functions dependent on the time interval between the successive challenge of influenza virus and pneumococcus, as well as the doses of pneumococcus. When dendritic cells were exposed to pneumococcus at 6 hr, but not 0 hr nor 24 hr after influenza virus infection, both virus and pneumococcus treated dendritic cells had greater cell apoptosis and expressed higher CD83 and CD86 than dendritic cells infected with influenza virus alone. Dendritic cells produced pro-inflammatory cytokines: TNF-α, IL-12 and IFN-γ synergistically to the successive viral and pneumococcal challenge. Whereas prior influenza virus infection suppressed the IL-10 response independent of the timing of the subsequent pneumococcal stimulation.

CONCLUSIONS

Our results demonstrated that successive challenge of dendritic cells with influenza virus and pneumococcus resulted in synergistic up-regulation of pro-inflammatory cytokines with simultaneous down-regulation of anti-inflammatory cytokine, which may explain the immuno-pathogenesis of this important co-infection.

T-cell receptor specificity of CD8(+) Tregs in allotransplantation

Recent studies in the field of CD8(+) Tregs have allowed a better identification and characterization of this subset of regulatory cells. Their key role in the regulation of allogeneic responses is now well established. To take full advantage of CD8(+) Treg cells in future therapeutic applications, a better knowledge is required, particularly concerning the contribution of the T-cell receptor (TCR) in cell function as well as the role and importance of its antigenic specificity. Here, we focused on the CD8(+)CD45RC(low) Tregs, which in rats induce an indefinite long-term allograft acceptance. We summarized recent findings on their interaction properties with antigen-presenting cells. Identification of the antigenic targets and TCR repertoire of CD8(+) Tregs will allow a better understanding of their recognition properties and will highlight the potential of such of specific population in cell-based treatment.

Type 1 responses of human Vγ9Vδ2 T cells to influenza A viruses

γδ T cells are essential constituents of antimicrobial and antitumor defenses. We have recently reported that phosphoantigen isopentenyl pyrophosphate (IPP)-expanded human Vγ9Vδ2 T cells participated in anti-influenza virus immunity by efficiently killing both human and avian influenza virus-infected monocyte-derived macrophages (MDMs) in vitro. However, little is known about the noncytolytic responses and trafficking program of γδ T cells to influenza virus. In this study, we found that Vγ9Vδ2 T cells expressed both type 1 cytokines and chemokine receptors during influenza virus infection, and IPP-expanded cells had a higher capacity to produce gamma interferon (IFN-γ). Besides their potent cytolytic activity against pandemic H1N1 virus-infected cells, IPP-activated γδ T cells also had noncytolytic inhibitory effects on seasonal and pandemic H1N1 viruses via IFN-γ but had no such effects on avian H5N1 or H9N2 virus. Avian H5N1 and H9N2 viruses induced significantly higher CCL3, CCL4, and CCL5 production in Vγ9Vδ2 T cells than human seasonal H1N1 virus. CCR5 mediated the migration of Vγ9Vδ2 T cells toward influenza virus-infected cells. Our findings suggest a novel therapeutic strategy of using phosphoantigens to boost the antiviral activities of human Vγ9Vδ2 T cells against influenza virus infection.

The aminobisphosphonate pamidronate controls influenza pathogenesis by expanding a gammadelta T cell population in humanized mice

As shown in humanized mice, a population of Vγ9Vδ2 T cells can reduce the severity and mortality of disease caused by infection with human and avian influenza viruses.

There are few antiviral drugs for treating influenza, and the emergence of antiviral resistance has further limited the available therapeutic options. Furthermore, antivirals are not invariably effective in severe influenza, such as that caused by H5N1 viruses. Thus, there is an urgent need to develop alternative therapeutic strategies. Here, we show that human Vγ9Vδ2 T cells expanded by the aminobisphosphonate pamidronate (PAM) kill influenza virus–infected cells and inhibit viral replication in vitro. In Rag2^−/−γc^−/− immunodeficient mice reconstituted with human peripheral mononuclear cells (huPBMCs), PAM reduces disease severity and mortality caused by human seasonal H1N1 and avian H5N1 influenza virus, and controls the lung inflammation and viral replication. PAM has no such effects in influenza virus–infected Rag2^−/−γc^−/− mice reconstituted with Vγ9Vδ2 T cell–depleted huPBMCs. Our study provides proof-of-concept of a novel therapeutic strategy for treating influenza by targeting the host rather than the virus, thereby reducing the opportunity for the emergence of drug-resistant viruses. As PAM has been commonly used to treat osteoporosis and Paget’s disease, this new application of an old drug potentially offers a safe and readily available option for treating influenza.

Novel mechanisms of immune modulation of natalizumab in multiple sclerosis patients

The goal of this study was to investigate the effects of natalizumab therapy on the immune cell composition and phenotype in the blood of relapsing MS patients treated over the course of 12 months. We collected peripheral blood from 26 RRMS patients before treatment onset, and then 6 and 12 months after therapy. PBMC was isolated and then analyzed for phenotypic characteristics by FACS and for cytokine production by ELISA. The results of our studies showed changes in both numbers and activation states of immune cells following therapy. These changes were observed at the 6 month timepoint and generally persisted through the 12 month timepoint. The proportions of NK cells (CD3⁻CD56+) and hematopoetic stem cells (CD34+lin⁻) were increased after natalizumab treatment. Decreases were noted in numbers of CD14+ monocytes, and possibly their migratory potential, since their expression levels of α4β1 were decreased. Relative numbers of CD20+ B cells were increased, but the proportion of CD20+ cells expressing high levels of α4β1 integrin was decreased. While proportions of CD4+ and CD8+ T cells did not change, the percentage of cells expressing α4β1 integrin was significantly decreased for both subsets. Natalizumab therapy produces a number of phenotypic changes in the immune composition of peripheral blood. These changes may help to explain both the mechanisms of action of natalizumab and also shed light on the potential for the observed increase in PML in these patients.

Reproductive immunology: a focus on the role of female sex hormones and other gender-related factors

Reproductive immunology has attracted the attention of researchers interested in fertility and pregnancy as well as those interested in immunity and autoimmunity. Over the past couple of decades, a wealth of data on the immune-reproductive interactions has been generated. This issue of the Journal will examine several topics including the role of immune factors in the induction of anti-Ro antibody-mediated autoimmunity in neonates and the immunological effects of gender and sex hormones. The possible implications of the research reviewed here for the development of novel therapeutic approaches are also addressed.

Phenotypic and functional characterization of CD8(+) T regulatory cells

Increasing evidence shows the presence and significance of CD8+ T regulatory cells (CD8+ Tregs) in both human and rodent transplant recipients, as well as in autoimmune disease models. We, hereafter, review all available data on the phenotypic and functional characterization of CD8+ Tregs, and we also provide detailed protocols to purify them and analyze their suppressive function. Different subsets of dendritic cells (DCs) and CD4+ effector T cells may modulate the suppression mediated by CD8+ Tregs. By analyzing the proliferation of CFSE-labeled naïve CD4+CD25- T cells in coculture MLR and transwell experiments, we explored the mutual modulation of CD8+ Tregs, DC subsets, and CD4+ T effector cells. The suppressive function of CD8+ Tregs was mediated by both cell-contact-dependent and -independent mechanisms.

Generation of human Th1-like regulatory CD4+ T cells by an intrinsic IFN-γ- and T-bet-dependent pathway

Murine Foxp3(+) Treg have recently been shown to express T-bet, a transcription factor characteristic of Th1 effector cells. A human Treg phenotype equivalent has not been reported. Here, we show that naïve human CD4(+) T cells incubated with low numbers of CD40-activated allogeneic B cells preferentially differentiate into alloantigen-specific CD4(hi) CD25(hi) Treg. These differentiated cells potently suppress effector T-cell responses and express T-bet, IFN-γ, and CXCR3, the features of Th1 effector cells. In contrast, co-culture of naïve CD4(+) T cells with high numbers of allogeneic B cells results in CD4(+) CD25(+) T cells that promote, rather than inhibit, effector T-cell responses, demonstrating the plasticity of CD4(+) T-cell differentiation in response to alloantigen-presenting B cells. The optimal accumulation of CD4(hi) CD25(hi) Treg induced using higher T cell:B cell co-culture ratios was dependent on the expression of T-bet and endogenously produced IFN-γ. Induction of Treg-mediated suppression function in the Treg population was not. As CXCR3 confers the preferential trafficking of T cells to tissue sites of IFN-γ, these human Th1-like Treg might be useful for modulating pathological Th1 effector responses, such as that occurring during graft-versus-host disease or graft rejection.