A cell culture model for T lymphocyte clonal anergy

STING Membrane Prevents Post-Surgery Tissue Adhesion and Tumor Recurrence of Colorectal Cancer

Surgery is the standard treatment regimen for resectable colorectal cancer (CRC). However, it is very hard to completely remove all cancer cells in clinical practice, leading to the high recurrence rates of the disease. Moreover, the post-surgery tissue adhesion greatly prevents the possibility of reoperation, significantly limiting the long-term surviving of CRC patients. To overcome CRC recurrence and avoid the post-surgery tissue adhesion, this work develops a novel stimulator of interferon genes "STING" membrane based on the coaxial electrospinning technology and hyaluronic acid modification. A reactive oxygen species responsive prodrug of gambogic acid (GB) and a potent STING agonist (CDN) are coloaded in the core-shell structure of the membrane, which endows the loaded drug with sustained and sequential release patterns. The localized delivery of GB and CDN can selectively induce efficient immunogenic cell death of cancer cells and then evoke the systemic anticancer immunity by activating the Cyclic GMP-AMP (cGAMP) synthase/STING pathway. As-designed "STING" membrane not only safely prevents tumor recurrence through the synergistic chemoimmunotherapy but also efficiently avoids the post-surgery tissue adhesion, facilitating the clinical intervention of CRC.

Pulmonary toxicity of immune checkpoint immunotherapy

Cancer remains a leading cause of mortality on a global scale. Lung cancer, specifically non-small cell lung cancer (NSCLC), is a prominent contributor to this burden. The management of NSCLC has advanced substantially in recent years, with immunotherapeutic agents, such as immune checkpoint inhibitors (ICIs), leading to improved patient outcomes. Although generally well tolerated, the administration of ICIs can result in unique side effects known as immune-related adverse events (irAEs). The occurrence of irAEs involving the lungs, specifically checkpoint inhibitor pneumonitis (CIP), can have a profound effect on both future therapy options and overall survival. Despite CIP being one of the more common serious irAEs, limited treatment options are currently available, in part due to a lack of understanding of the underlying mechanisms involved in its development. In this Review, we aim to provide an overview of the epidemiology and clinical characteristics of CIP, followed by an examination of the emerging literature on the pathobiology of this condition.

Immune Checkpoint Inhibitors in Recipients of Renal Allografts

Kidney transplant recipients are at increased risk of malignancy as a result of immunosuppression and are increasingly exposed to checkpoint inhibitors (CPIs). However, CPI therapy can precipitate allograft rejection. This review aims to summarize the current literature describing the epidemiology, immunological mechanisms, diagnosis, and treatment of CPI-associated allograft rejection.Initial studies of CPIs suggested allograft rejection post commencement of CPIs occured commonly (40-60%), occurring between 2 and 6 weeks after CPI initiation, with a cancer response rate approaching 50%. More recent studies with predefined, structured immunosuppressive regimens have seen rejection rates of 0-12.5%, with rejection occurring later. Allograft biopsy remains the mainstay of diagnosis; however, noninvasive tools are emerging, including donor-derived cell-free DNA, urinary chemokine assessment, and defining alloreactive T-cell clones prior to or during CPI therapy.

Classic costimulatory interactions in MAIT cell responses: from gene expression to immune regulation

Mucosa-associated invariant T (MAIT) cells are evolutionarily conserved, innate-like T lymphocytes with enormous immunomodulatory potentials. Due to their strategic localization, their invariant T cell receptor (iTCR) specificity for major histocompatibility complex-related protein 1 (MR1) ligands of commensal and pathogenic bacterial origin, and their sensitivity to infection-elicited cytokines, MAIT cells are best known for their antimicrobial characteristics. However, they are thought to also play important parts in the contexts of cancer, autoimmunity, vaccine-induced immunity, and tissue repair. While cognate MR1 ligands and cytokine cues govern MAIT cell maturation, polarization, and peripheral activation, other signal transduction pathways, including those mediated by costimulatory interactions, regulate MAIT cell responses. Activated MAIT cells exhibit cytolytic activities and secrete potent inflammatory cytokines of their own, thus transregulating the biological behaviors of several other cell types, including dendritic cells, macrophages, natural killer cells, conventional T cells, and B cells, with significant implications in health and disease. Therefore, an in-depth understanding of how costimulatory pathways control MAIT cell responses may introduce new targets for optimized MR1/MAIT cell-based interventions. Herein, we compare and contrast MAIT cells and mainstream T cells for their expression of classic costimulatory molecules belonging to the immunoglobulin superfamily and the tumor necrosis factor (TNF)/TNF receptor superfamily, based not only on the available literature but also on our transcriptomic analyses. We discuss how these molecules participate in MAIT cells' development and activities. Finally, we introduce several pressing questions vis-à-vis MAIT cell costimulation and offer new directions for future research in this area.

Heterogeneity of Cholangiocarcinoma Immune Biology

Cholangiocarcinomas (CCAs) are aggressive tumors arising along the biliary tract epithelium, whose incidence and mortality are increasing. CCAs are highly desmoplastic cancers characterized by a dense tumor microenvironment (TME), in which each single component plays a fundamental role in shaping CCA initiation, progression and resistance to therapies. The crosstalk between cancer cells and TME can affect the recruitment, infiltration and differentiation of immune cells. According to the stage of the disease and to intra- and inter-patient heterogeneity, TME may contribute to either protumoral or antitumoral activities. Therefore, a better understanding of the effect of each immune cell subtype may open the path to new personalized immune therapeutic strategies for the management of CCA. In this review, we describe the role of immune cells in CCA initiation and progression, and their crosstalk with both cancer-associated fibroblasts (CAFs) and the cancer-stem-cell-like (CSC) niche.

CD8+ T cell activation in cancer comprises an initial activation phase in lymph nodes followed by effector differentiation within the tumor

Improvements in tumor immunotherapies depend on better understanding of the anti-tumor T cell response. By studying human tumor-draining lymph nodes (TDLNs), we found that activated CD8+ T cells in TDLNs shared functional, transcriptional, and epigenetic traits with TCF1+ stem-like cells in the tumor. The phenotype and TCR overlap suggested that these TDLN cells were precursors to tumor-resident stem-like CD8+ T cells. Murine tumor models revealed that tumor-specific CD8+ T cells were activated in TDLNs but lacked an effector phenotype. These stem-like cells migrated into the tumor, where additional co-stimulation from antigen-presenting cells drove effector differentiation. This model of CD8+ T cell activation in response to cancer is different from that of canonical CD8+ T cell activation to acute viruses, and it proposes two stages of tumor-specific CD8+ T cell activation: initial activation in TDLNs and subsequent effector program acquisition within the tumor after additional co-stimulation.

Antigen presentation induced variation in ovalbumin sensitization between chicken and duck species

The difference in the allergenicity of chicken ovalbumin (C-OVA) and duck ovalbumin (D-OVA) can be related to their differences in antigen presentation. This study explored the differences in uptake between C-OVA and D-OVA through fluorescence dye-labeling, DC antigen presentation, and the immune response of T cells by using C-OVA and D-OVA allergic animal and cell models. The ileum DCs of mice in the C-C group took up more C-OVA than that of D-D and C-D groups through in vivo imaging. Furthermore, C-OVA induced the maturation of DCs in mice in the C-C group as shown in the up-regulation of the expressions of MHC II, CD86 and CD80 on the surface of DCs, and enhanced the ability of antigen presentation. In addition, C-OVA induced the maturation of DCs, promoted the differentiation of T cells into Th2 cells, increased the secretion of the cytokine IL-4 and specific antibody s-IgE, and thus generated an immune response. However, sensitized and cross sensitized D-OVA (D-D and C-D groups) couldn't induce the maturation of DCs, and induced less differentiation of T cells and lower secretion of cytokines compared to C-OVA. In conclusion, the differences in antigen presentation was one of the important factors resulting in the differences in the sensitization between C-OVA and D-OVA.

Liraglutide protects β-cells in novel human islet spheroid models of type 1 diabetes

To enable accurate, high-throughput and longer-term studies of the immunopathogenesis of type 1 diabetes (T1D), we established three in-vitro islet-immune injury models by culturing spheroids derived from primary human islets with proinflammatory cytokines, activated peripheral blood mononuclear cells or HLA-A2-restricted preproinsulin-specific cytotoxic T lymphocytes. In all models, β-cell function declined as manifested by increased basal and decreased glucose-stimulated insulin release (GSIS), and decreased intracellular insulin content. Additional hallmarks of T1D progression such as loss of the first-phase insulin response (FFIR), increased proinsulin-to-insulin ratios, HLA-class I expression, and inflammatory cytokine release were also observed. Using these models, we show that liraglutide, a glucagon-like peptide 1 receptor agonist, prevented loss of GSIS under T1D-relevant stress, by preserving the FFIR and decreasing immune cell infiltration and cytokine secretion. Our results corroborate that liraglutide mediates an anti-inflammatory effect that aids in protecting β-cells from the immune-mediated attack that leads to T1D.

Immunologic and dose dependent effects of rapamycin and its evolving role in chemoprevention

Rapamycin inhibits the mechanistic (formally mammalian) target of rapamycin (mTOR), an evolutionarily conserved intracellular kinase that influences activation of growth signaling pathways and immune responses to malignancy. Rapamycin has been found to have both immunosuppressant and immunostimulatory effects throughout the innate and adaptive responses based on the inhibition of mTOR signaling. While the immunosuppressant properties of rapamycin and mTOR inhibition explain rapamycin's success in the prevention of transplant rejection, the immunostimulatory characteristics are likely partially responsible for rapamycin's anti-neoplastic effects. The immunologic response to rapamycin is at least partially dependent on the dose and administration schedule, with lower doses inducing immunostimulation and intermittent dosing promoting immune function while limiting metabolic and immunosuppressant toxicities. In addition to its FDA-approved application in advanced malignancies, rapamycin may be effective as a chemopreventive agent, suspending progression of low-grade cancers, preventing invasive conversion of in situ malignancy, or delaying malignant transformation of established pre-malignant conditions.

Balancing B cell responses to the allograft: implications for vaccination

Balancing enough immunosuppression to prevent allograft rejection and yet maintaining an intact immune system to respond to vaccinations, eliminate invading pathogens or cancer cells is an ongoing challenge to transplant physicians. Antibody mediated allograft rejection remains problematic in kidney transplantation and is the most common cause of graft loss despite current immunosuppressive therapies. The goal of immunosuppressive therapies is to prevent graft rejection; however, they prevent optimal vaccine responses as well. At the center of acute and chronic antibody mediated rejection and vaccine responses is the B lymphocyte. This review will highlight the role of B cells in alloimmune responses including the dependency on T cells for antibody production. We will discuss the need to improve vaccination rates in transplant recipients and present data on B cell populations and SARS-CoV-2 vaccine response rates in pediatric kidney transplant recipients.

Modulation of Regulatory T Cells Activity by Distinct CD80 and CD86 Interactions With CD28/CTLA-4 in Chagas Cardiomyopathy

Chagas cardiomyopathy is the symptomatic cardiac clinical form (CARD) of the chronic phase of Chagas disease caused by Trypanosoma cruzi infection. It was described as the most fibrosing cardiomyopathies, affecting approximately 30% of patients during the chronic phase. Other less frequent symptomatic clinical forms have also been described. However, most patients who progress to the chronic form develop the indeterminate clinical form (IND), may remain asymptomatic for life, or develop some cardiac damage. Some mechanisms involved in the etiology of the clinical forms of Chagas disease have been investigated. To characterize the contribution of CD80 and CD86 co-stimulatory molecules in the activation of different CD4⁺ (Th1, Th2, Th17, and Treg) and CD8⁺ T lymphocyte subsets, we used blocking antibodies for CD80 and CD86 receptors of peripheral blood mononuclear cells (PBMC) in cultures with T. cruzi antigens from non-infected (NI), IND, and CARD individuals. We demonstrated a higher frequency of CD8⁺ CD25⁺ T lymphocytes and CD8⁺ Treg cells after anti-CD80 antibody blockade only in the CARD group. In contrast, a lower frequency of CD4⁺ Treg lymphocytes after anti-CD86 antibody blockade was found only in IND patients. A higher frequency of CD4⁺ Treg CD28⁺ lymphocytes, as well as an association between CD4⁺ Treg lymphocytes and CD28⁺ expression on CD4⁺ Treg cells in the CARD group, but not in IND patients, and once again only after anti-CD80 antibody blockade, was observed. We proposed that Treg cells from IND patients could be activated via CD86-CTLA-4 interaction, leading to modulation of the immune response only in asymptomatic patients with Chagas disease, while CD80 may be involved in the proliferation control of T CD8⁺ lymphocytes, as also in the modulation of regulatory cell activation via CD28 receptor. For the first time, our data highlight the role of CD80 in modulation of Treg lymphocytes activation in patients with CARD, highlighting a key molecule in the development of Chagas cardiomyopathy.

A variety of 'exhausted' T cells in the tumor microenvironment

In T cell biology, 'exhaustion' was initially described as a hyporesponsive state in CD8 + T cells during chronic infections. Recently, exhaustion has been recognized as a T-cell dysfunctional state in the tumor microenvironment (TME). The term 'exhaustion' is used mainly to refer to effector T cells with a reduced capacity to secrete cytokines and an increased expression of inhibitory receptors. The upregulation of exhaustion-related inhibitory receptors, including programmed cell death protein 1 (PD-1), in such T cells has been associated with the development of tumors, prompting the development of immune checkpoint inhibitors. In addition to CD8 + T cells, CD4 + T cells, including the regulatory T (Treg) cell subset, perform a wide variety of functions within the adaptive immune system. Upregulation of the same inhibitory receptors that are associated with CD8 + T-cell exhaustion has also been identified in CD4 + T cells in chronic infections and cancers, suggesting a similar CD4 + T-cell exhaustion phenotype. For instance, high expression of PD-1 has been observed in Treg cells in the TME, and such Treg cells can play an important role in the resistance to PD-1 blockade therapies. Furthermore, recent progress in single-cell RNA sequencing has shown that CD4 + T cells with cytotoxic activity are also vulnerable to exhaustion. In this review, we will discuss novel insights into various exhausted T-cell subsets, which could reveal novel therapeutic targets and strategies to induce a robust antitumor immune response.

CD81 costimulation skews CAR transduction toward naive T cells

Chimeric antigen receptors (CARs) are engineered, artificial T cell receptors that can redirect cytotoxic immune T cells to eliminate cancer. Previous reports describe the benefit of less differentiated naive T cell subtypes for the purpose of CAR therapy. Here we test CD81, a T cell costimulator that preferentially activates naive T cells, for CAR engineering. We show that CD81 costimulation of naive T cells prior to CAR transduction can lead to enhanced CAR expression in this T cell subset.

Adoptive cellular therapy using chimeric antigen receptors (CARs) has revolutionized our treatment of relapsed B cell malignancies and is currently being integrated into standard therapy. The impact of selecting specific T cell subsets for CAR transduction remains under investigation. Previous studies demonstrated that effector T cells derived from naive, rather than central memory T cells mediate more potent antitumor effects. Here, we investigate a method to skew CAR transduction toward naive T cells without physical cell sorting. Viral-mediated CAR transduction requires ex vivo T cell activation, traditionally achieved using antibody-mediated strategies. CD81 is a T cell costimulatory molecule that when combined with CD3 and CD28 enhances naive T cell activation. We interrogate the effect of CD81 costimulation on resultant CAR transduction. We identify that upon CD81-mediated activation, naive T cells lose their identifying surface phenotype and switch to a memory phenotype. By prelabeling naive T cells and tracking them through T cell activation and CAR transduction, we document that CD81 costimulation enhanced naive T cell activation and resultantly generated a CAR T cell product enriched with naive-derived CAR T cells.

Extensive functional comparisons between chimeric antigen receptors and T cell receptors highlight fundamental similarities

Though TCRs have been subject to limited engineering in the context of therapeutic design and optimization, they are used largely as found in nature. On the other hand, CARs are artificial, composed of different segments of proteins that function in the immune system. This characteristic raises the possibility of altered response to immune regulatory stimuli. Here we describe a large-scale, systematic comparison of CARs and TCRs across 5 different pMHC targets, with a total of 19 constructs examined in vitro. These functional measurements include CAR- and TCR-mediated activation, proliferation, and cytotoxicity in both acute and chronic settings. Surprisingly, we find no consistent difference between CARs and TCRs as receptor classes with respect to their relative sensitivity to major regulators of T cell activation: PD-L1, CD80/86 and IL-2. Though TCRs often emerge from human blood directly as potent, selective receptors, CARs must be heavily optimized to attain these properties for pMHC targets. Nonetheless, when iteratively improved and compared head to head in functional tests, CARs appear remarkably similar to TCRs with respect to immune modulation.

The landscape of bispecific T cell engager in cancer treatment

T cell-based immunotherapies have revolutionized treatment paradigms in various cancers, however, limited response rates secondary to lack of significant T-cell infiltration in the tumor site remain a major problem. To address this limitation, strategies for redirecting T cells to treat cancer are being intensively investigated, while the bispecific T cell engager (BiTE) therapy constitutes one of the most promising therapeutic approaches. BiTE is a bispecific antibody construct with a unique function, simultaneously binding an antigen on tumor cells and a surface molecule on T cells to induce tumor lysis. BiTE therapy represented by blinatumomab has achieved impressive efficacy in the treatment of B cell malignancies. However, major mechanisms of resistance to BiTE therapy are associated with antigen loss and immunosuppressive factors such as the upregulation of immune checkpoints. Thus, modification of antibody constructs and searching for combination strategies designed to further enhance treatment efficacy as well as reduce toxicity has become an urgent issue, especially for solid tumors in which response to BiTE therapy is always poor. In particular, immunotherapies focusing on innate immunity have attracted increasing interest and have shown promising anti-tumor activity by engaging innate cells or innate-like cells, which can be used alone or complement current therapies. In this review, we depict the landscape of BiTE therapy, including clinical advances with potential response predictors, challenges of treatment toxicity and resistance, and developments of novel immune cell-based engager therapy.

Managing side effects of immune checkpoint inhibitors in breast cancer

Immune-checkpoint inhibitors (ICIs) represent a major development in cancer therapy. The indications for these agents continue to expand across malignancies and disease settings. For years breast cancer (BC) has been considered immunologically quiescent compared with other tumor types. However, recent findings highlighted the immunogenicity of some BCs and paved the way for clinical trials of immunotherapy in BC that led to recent landmark approvals. As a drawback, the safety profile of ICIs is shaped by a specific spectrum of immune-related adverse events (irAEs) that can vary according to ICI class and tumor histology. This review will discuss the epidemiology of these adverse events, their kinetics, risk factors and the most important aspects in their management. A particular focus will be put on BC as the current landscape of immunotherapy for this disease is rapidly increasing the number of people treated with ICIs, thus susceptible to irAEs.

CD28 engagement inhibits CD73-mediated regulatory activity of CD8+ T cells

CD28 is required for T cell activation as well as the generation of CD4+Foxp3+ Treg. It is unclear, however, how CD28 costimulation affects the development of CD8+ T cell suppressive function. Here, by use of Hepa1.6.gp33 in vitro killing assay and B16.gp33 tumor mouse model we demonstrate that CD28 engagement during TCR ligation prevents CD8+ T cells from becoming suppressive. Interestingly, our results showed that ectonucleotidase CD73 expression on CD8+ T cells is upregulated in the absence of CD28 costimulation. In both murine and human tumor-bearing hosts, CD73 is upregulated on CD28-CD8+ T cells that infiltrate the solid tumor. UPLC-MS/MS analysis revealed that CD8+ T cells activation without CD28 costimulation produces elevated levels of adenosine and that CD73 mediates its production. Adenosine receptor antagonists block CD73-mediated suppression. Our data support the notion that CD28 costimulation inhibits CD73 upregulation and thereby prevents CD8+ T cells from becoming suppressive. This study uncovers a previously unidentified role for CD28 costimulation in CD8+ T cell activation and suggests that the CD28 costimulatory pathway can be a potential target for cancer immunotherapy.

Calcium signaling on Jurkat T cells induced by microbeads coated with novel peptide ligands specific to human CD3ε

CD3ε is expressed on T lymphocytes as a part of the T cell receptor (TCR)-CD3 complex. Together with other CD3 molecules, CD3ε is responsible for the activation of T cells via transducing the event of antigen recognition by the TCR into intracellular signaling cascades. The present study first aims to identify a novel peptide ligand that binds to human CD3ε in a specific manner and to perform an initial evaluation of its biological efficacy on the human T cell line, Jurkat cells. We screened a phage-display peptide library against human CD3ε using a subtractive biopanning process, from which we identified 13 phage clones displaying unique peptide sequences. One dominant phage clone displaying the 7 amino acid sequence of WSLGYTG, which occupied 90% of tested plaques (18 out of 20) after the 5th round of biopanning, demonstrated a superior binding behavior to other clones in the binding assays against recombinant CD3ε on microbeads or Jurkat cells. The synthesized peptide also showed specific binding to Jurkat cells in a dose-dependent manner but not to B cell lymphoma line, 2PK3 cells. Molecular modeling and docking simulation confirmed that the selected peptide ligand in an energetically stable conformation binds to a pocket of CD3ε that is not hidden by either CD3γ or CD3δ. Lastly, magnetic microbeads conjugated with the synthesized peptide ligands showed a weak but specific association with Jurkat cells and induced the calcium flux, a hallmark indication of proximal T cell receptor signaling, which gave rise to an enhancement of IL-2 section and cell proliferation. The novel peptide ligand and its various multivalent forms have a great potential in applications related to T cell biology and T cell immunotherapy.

Immunologic evaluation and genetic defects of apoptosis in patients with autoimmune lymphoproliferative syndrome (ALPS)

Apoptosis plays an important role in controlling the adaptive immune response and general homeostasis of the immune cells, and impaired apoptosis in the immune system results in autoimmunity and immune dysregulation. In the last 25 years, inherited human diseases of the Fas-FasL pathway have been recognized. Autoimmune lymphoproliferative syndrome (ALPS) is an inborn error of immunity, characterized clinically by nonmalignant and noninfectious lymphoproliferation, autoimmunity, and increased risk of lymphoma due to a defect in lymphocyte apoptosis. The laboratory hallmarks of ALPS are an elevated percentage of T-cell receptor αβ double negative T cells (DNTs), elevated levels of vitamin B12, soluble FasL, IL-10, IL-18 and IgG, and defective in vitro Fas-mediated apoptosis. In order of frequency, the genetic defects associated with ALPS are germinal and somatic ALPS-FAS, ALPS-FASLG, ALPS-CASP10, ALPS-FADD, and ALPS-CASP8. Partial disease penetrance and severity suggest the combination of germline and somatic FAS mutations as well as other risk factor genes. In this report, we summarize human defects of apoptosis leading to ALPS and defects that are known as ALPS-like syndromes that can be clinically similar to, but are genetically distinct from, ALPS. An efficient genetic and immunological diagnostic approach to patients suspected of having ALPS or ALPS-like syndromes is essential because this enables the establishment of specific therapeutic strategies for improving the prognosis and quality of life of patients.

The Function and Role of the Th17/Treg Cell Balance in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic, inflammatory, and autoimmune disorder. The pathogenesis of IBD is not yet clear. Studies have shown that the imbalance between T helper 17 (Th17) and regulatory T (Treg) cells, which differentiate from CD4⁺ T cells, contributes to IBD. Th17 cells promote tissue inflammation, and Treg cells suppress autoimmunity in IBD. Therefore, Th17/Treg cell balance is crucial. Some regulatory factors affecting the production and maintenance of these cells are also important for the proper regulation of the Th17/Treg balance; these factors include T cell receptor (TCR) signaling, costimulatory signals, cytokine signaling, bile acid metabolites, and the intestinal microbiota. This article focuses on our understanding of the function and role of the balance between Th17/Treg cells in IBD and these regulatory factors and their clinical significance in IBD.

Overcoming Challenges in Process Development of Cellular Therapies

PURPOSE OF THE REVIEW

Cellular therapy using chimeric antigen receptor (CAR) T cells as a treatment option for patients with lymphoma and leukemia has proven to be remarkably efficacious. This success has sparked the development of new cellular therapy products for numerous indications. Similar to pharmaceutical products, challenges exist at nearly every stage of process development; however, the unique nature of a cellular therapy product can present exceptional challenges that are just beginning to emerge. The purpose of this review is to explore some of the most common challenges experienced during the early phases of development of CAR T cell products and to provide suggestions for navigating these challenges.

RECENT FINDINGS

Recent articles focused on CAR T cells are highlighted with special attention on aspects that relate to CAR T cell process development and clinical manufacturing. We examine the various stages of process development for CAR T cells and outline some of the obstacles that must be overcome in order to move from pre-clinical development into clinical manufacturing. As the field of CAR T cell therapy continues to grow, it is important to quickly move new CAR T cell products into and through early phase clinical trials and to ensure that the result of these trials can be adequately compared. Having laboratory and clinical investigators and GMP manufacturing facilities aligned on the numerous aspects of new product development will facilitate this process.

T cell stimulation and expansion by SunTag-based clustering of anti-CD3/CD28 scFv

Therapeutic ex vivo T cell expansion is limited by low rates and poor functionality, especially for T cells from aged cancer patients. Here, we describe a novel method for T cell stimulation and expansion using a system named SunTag-based clustering of anti-CD3/CD28 scFv (SBCS). In this method, SunTag was used to recruit up to 13 copies of anti-CD3/CD28 scFv for T cell activation. Compared with the traditional method using immobilized CD3/CD28 antibodies, the SBCS system produced approximately 1.5-fold greater expansion of T cells from healthy donors, and more than 2-fold greater expansion of T cells from aged cancer patients after stimulation. The efficiency of expansion depended mainly on the concentration of the clustered polymers of anti-CD3 scFv rather than anti-CD28 scFv. We also demonstrated that the SBCS-expanded T cells could be used to prepare functional chimeric antigen receptor modified T cells for antitumor therapy.

Extracellular Vesicles and Tumor-Immune Escape: Biological Functions and Clinical Perspectives

The modulation of the immune system is one of the hallmarks of cancer. It is now widely described that cancer cells are able to evade the immune response and thus establish immune tolerance. The exploration of the mechanisms underlying this ability of cancer cells has always attracted the scientific community and is the basis for the development of new promising cancer therapies. Recent evidence has highlighted how extracellular vesicles (EVs) represent a mechanism by which cancer cells promote immune escape by inducing phenotypic changes on different immune cell populations. In this review, we will discuss the recent findings on the role of tumor-derived extracellular vesicles (TEVs) in regulating immune checkpoints, focusing on the PD-L1/PD-1 axis.

Transmural impedance detects graded changes of inflammation in experimental colitis

Ulcerative colitis is a chronic disease in which the mucosa of the colon or rectum becomes inflamed. An objective biomarker of inflammation will provide quantitative measures to support qualitative assessment during an endoscopic examination. Previous studies show that transmural electrical impedance is a quantifiable biomarker of inflammation. Here, we hypothesize that impedance detects spatially restricted areas of inflammation, thereby allowing the distinction between regions that differ in their severity of inflammation. A platinum ball electrode was placed into minimally inflamed (i.e. normal) or 2,4,6-trinitrobenzene sulphonic acid (TNBS)-inflamed colonic regions of rats and impedance measurements obtained by passing current between the intraluminal and subcutaneous return electrode. Histology of the colon was correlated with impedance measurements. The impedance of minimally inflamed (normal) tissue was 1.5-1.9 kΩ. Following TNBS injection, impedance significantly decreased within the inflammatory penumbra (p < 0.05), and decreased more in the inflammatory epicentre (p = 0.02). Histological damage correlated with impedance values (p < 0.05). Thus, impedance values of 1.5-1.9, 1.3-1.4 and 0.9-1.1 kΩ corresponded to minimally inflamed, mildly inflamed and moderately inflamed tissue, respectively. In conclusion, transmural impedance is an objective, spatially localized biomarker of mucosal integrity, and distinguishes between severities of intestinal inflammation.

Sequence Multiplicity within Spherical Nucleic Acids

The synthesis and evaluation of spherical nucleic acids (SNAs) incorporating two physically and chemically distinct classes of oligonucleotides (ODNs) at programmed ratios are described. These SNAs are single entity agents that enter the same target cell at defined stoichiometries, and as such allow one to control important cell signaling and regulatory processes. To study the effect of sequence multiplicity within such structures, we synthesized SNAs consisting of a mixture of class A CpG and class B CpG, immunostimulatory ODNs that activate two different toll-like receptor 9 signaling pathways, each in a sequence-specific fashion. These dual-CpG SNAs exhibit high cellular uptake and codelivery of the two ODNs, relative to mixtures of the linear ODN counterparts, and remain highly associated inside the cell over time. Furthermore, the dual-CpG SNAs augment dendritic cell maturation, compared to the same amounts of oligonucleotides delivered in linear or SNA form but not conjugated to one another. Consequently, these structures constitute a platform for designing oligonucleotide-based combination therapeutics with highly tailorable activities.

Molecular and Cellular Functions of CTLA-4

Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) is an inhibitory receptor belonging to the CD28 immunoglobulin subfamily, expressed primarily by T-cells. Its ligands, CD80 and CD86, are typically found on the surface of antigen-presenting cells and can either bind CD28 or CTLA-4, resulting in a costimulatory or a co-inhibitory response, respectively. Because of its dampening effect, CTLA-4 is a crucial regulator of T-cell homeostasis and self-tolerance. The mechanisms by which CTLA-4 exerts its inhibitory function can be categorized as either cell-intrinsic (affects the CTLA-4 expressing T-cell) or cell-extrinsic (affects secondary cells). Research from the last decade has shown that CTLA-4 mainly acts in a cell-extrinsic manner via its competition with CD28, CTLA-4-mediated trans-endocytosis of CD80 and CD86, and its direct tolerogenic effects on the interacting cell. Nonetheless, intrinsic CTLA-4 signaling has been implicated in T-cell motility and the regulation of CTLA-4 its subcellular localization amongst others. CTLA-4 is well recognized as a key immune checkpoint and has gained significant momentum as a therapeutic target in the field of autoimmunity and cancer. In this chapter, we describe the role of costimulation in immune response induction as well as the main mechanisms by which CTLA-4 can inhibit this process.

In situ repurposing of dendritic cells with CRISPR/Cas9-based nanomedicine to induce transplant tolerance

Organ transplantation is the only effective method to treat end-stage organ failure. However, it is continuously plagued by immune rejection, which is mostly caused by T cell-mediated reactions. Dendritic cells (DCs) are professional antigen-presenting cells, and blocking the costimulatory signaling molecule CD40 in DCs inhibits T cell activation and induces transplant tolerance. In this study, to relieve graft rejection, Cas9 mRNA (mCas9) and a guide RNA targeting the costimulatory molecule CD40 (gCD40) were prepared and encapsulated into poly(ethylene glycol)-block-poly(lactide-co-glycolide) (PEG-b-PLGA)-based cationic lipid-assisted nanoparticles (CLAN), denoted CLANmCas9/gCD40. CLAN effectively delivered mCas9/gCD40 into DCs and disrupted CD40 in DCs at the genomic level both in vitro and in vivo. After intravenous injection into an acute mouse skin transplant model, CLANmCas9/gCD40-mediated CD40 disruption significantly inhibited T cell activation, which reduced graft damage and prolonged graft survival. This work provides a promising strategy for reprogramming DCs with nanoparticles carrying the CRISPR/Cas9 system to abate transplant rejection.

The Role of Tumor-Derived Vesicles in the Regulation of Antitumor Immunity

In this article, we present a comprehensive, updated, and elucidative review of the current knowledge on the function played by tumor-derived vesicles (TDVs) in the crosstalk between tumor and immune cells. Characterization of the structure, biogenesis, and the major functions of TDVs is reported. The review focuses on particular ways of suppression or activation of CD4+/CD8+ T cells by tumor-derived vesicles. Tumor-derived vesicles play an important role in the suppression of antitumor immunity. During the last 15 years, vesicle research has elucidated and improved our knowledge about the role of the vesicles in intercellular communication. Nevertheless, there are still blinds spots concerning vesicle heterogeneity and isolation methods, their uptake by target cells, and the role of mRNA in T-cell transformation or suppression. Along with the substantial progress in understanding of the role of tumor-derived vesicles in intercellular communication, novel antitumor therapy strategies based on vesicle inhibition in a tumor microenvironment are likely to appear very soon.

TCR activation mimics CD127lowPD-1high phenotype and functional alterations of T lymphocytes from septic shock patients

Background

Sepsis is the leading cause of mortality for critically ill patients worldwide. Patients develop T lymphocyte dysfunctions leading to T-cell exhaustion associated with increased risk of death. As interleukin-7 (IL-7) is currently tested in clinical trials to reverse these dysfunctions, it is important to evaluate the expression of its specific CD127 receptor on the T-cell surface of patients with septic shock. Moreover, the CD127^lowPD-1^high phenotype has been proposed as a T-cell exhaustion marker in chronic viral infections but has never been evaluated in sepsis. The objective of this study was first to evaluate CD127 and CD127^lowPD-1^high phenotype in septic shock in parallel with functional T-cell alterations. Second, we aimed to reproduce septic shock–induced T-cell alterations in an ex vivo model.

Methods

CD127 expression was followed at the protein and mRNA levels in patients with septic shock and healthy volunteers. CD127^lowPD-1^high phenotype was also evaluated in parallel with T-cell functional alterations after ex vivo activation. To reproduce T-cell alterations observed in patients, purified T cells from healthy volunteers were activated ex vivo and their phenotype and function were evaluated.

Results

In patients, neither CD127 expression nor its corresponding mRNA transcript level was modified compared with normal values. However, the percentage of CD127^lowPD-1^high T cells was increased while T cells also presented functional alterations. CD127^lowPD-1^high T cells co-expressed HLA-DR, an activation marker, suggesting a role for T-cell activation in the development of this phenotype. Indeed, T-cell receptor (TCR) activation of normal T lymphocytes ex vivo reproduced the increase of CD127^lowPD-1^high T cells and functional alterations following a second stimulation, as observed in patients. Finally, in this model, as observed in patients, IL-7 could improve T-cell proliferation.

Conclusions

The proportion of CD127^lowPD-1^high T cells in patients was increased compared with healthy volunteers, although no global CD127 regulation was observed. Our results suggest that TCR activation participates in the occurrence of this T-cell population and in the development of T-cell alterations in septic shock. Furthermore, we provide an ex vivo model for the investigation of the pathophysiology of sepsis-induced T-cell immunosuppression and the testing of innovative immunostimulant treatments.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-2305-5) contains supplementary material, which is available to authorized users.

Role of Exosomes in the Regulation of T-cell Mediated Immune Responses and in Autoimmune Disease

: T-cell mediated immune responses should be regulated to avoid the development of autoimmune or chronic inflammatory diseases. Several mechanisms have been described to regulate this process, namely death of overactivated T cells by cytokine deprivation, suppression by T regulatory cells (Treg), induction of expression of immune checkpoint molecules such as CTLA-4 and PD-1, or activation-induced cell death (AICD). In addition, activated T cells release membrane microvesicles called exosomes during these regulatory processes. In this review, we revise the role of exosome secretion in the different pathways of immune regulation described to date and its importance in the prevention or development of autoimmune disease. The expression of membrane-bound death ligands on the surface of exosomes during AICD or the more recently described transfer of miRNA or even DNA inside T-cell exosomes is a molecular mechanism that will be analyzed.

Method of Generating Tolerogenic Maturation-Resistant Dendritic Cells and Testing for Their Immune-Regulatory Functions In Vivo in the Context of Transplantation

During that past two decades, advances in techniques for generating in vitro immune-suppressive dendritic cells (DCs) have heralded the use of these pro-tolerogenic DCs as therapeutics against transplant rejection and autoimmune diseases. In transplantation, previous dogma assumed that systemically administered therapeutic DCs bearing donor antigens (Ags) control the anti-donor response by directly interacting with anti-donor T cells in vivo. However, recent evidence indicates that the exogenously-administered therapeutic DCs instead function as Ag-transporting cells that transfer donor Ags to recipient's Ag-presenting cells (APCs) for presentation to T cells. In secondary lymphoid organs, presentation of acquired donor Ags by recipient's quiescent DCs triggers deficient activation and eventual apoptosis of donor-specific effector T cells, leading to a relative increase in the percentage of donor-specific regulatory T cells. This chapter describes the methodology to generate in vitro immune-suppressive DCs that are resistant to maturation, and to assess in vivo both their survival and their ability to regulate donor-specific T cells in a mouse model.

A comprehensive understanding of the gut mucosal immune system in allergic inflammation

Despite its direct exposure to huge amounts of microorganisms and foreign and dietary antigens, the gut mucosa maintains intestinal homeostasis by utilizing the mucosal immune system. The gut mucosal immune system protects the host from the invasion of infectious pathogens and eliminates harmful non-self antigens, but it allows the cohabitation of commensal bacteria in the gut and the entry of dietary non-self antigens into the body via the mucosal surface. These physiological and immunological activities are regulated by the ingenious gut mucosal immune network, comprising such features as gut-associated lymphoid tissue, mucosal immune cells, cytokines, chemokines, antimicrobial peptides, secretory IgA, and commensal bacteria. The gut mucosal immune network keeps a fine tuned balance between active immunity (against pathogens and harmful non-self antigens) and immune tolerance (to commensal microbiota and dietary antigens), thus maintaining intestinal healthy homeostasis. Disruption of gut homeostasis results in persistent or severe gastrointestinal infection, inflammatory bowel disease, or allergic inflammation. In this review, we comprehensively introduce current knowledge of the gut mucosal immune system, focusing on its interaction with allergic inflammation.

Cofilin hyperactivation in HIV infection and targeting the cofilin pathway using an anti-α4β7 integrin antibody

A functional HIV cure requires immune reconstitution for lasting viremia control. A major immune dysfunction persisting in HIV infection is the impairment of T helper cell migration and homing to lymphoid tissues such as GALTs (gut-associated lymphoid tissues). ART (antiretroviral therapy) does not fully restore T cell motility for tissue repopulation. The molecular mechanism dictating this persistent T cell dysfunction is not understood. Cofilin is an actin-depolymerizing factor that regulates actin dynamics for T cell migration. Here, we demonstrate that blood CD4 T cells from HIV-infected patients (n = 193), with or without ART, exhibit significantly lower levels of cofilin phosphorylation (hyperactivation) than those from healthy controls (n = 100; ratio, 1.1:2.3; P < 0.001); cofilin hyperactivation is also associated with poor CD4 T cell recovery following ART. These results suggest an HIV-mediated systemic dysregulation of T cell motility that cannot be repaired solely by ART. We further demonstrate that stimulating blood CD4 T cells with an anti-human α₄β₇ integrin antibody can trigger signal transduction and modulate the cofilin pathway, partially restoring T cell motility in vitro. However, we also observed that severe T cell motility defect caused by high degrees of cofilin hyperactivation was not repairable by the anti-integrin antibody, demonstrating a mechanistic hindrance to restore immune functions in vivo. Our study suggests that cofilin is a key molecule that may need to be therapeutically targeted early for T cell tissue repopulation, immune reconstitution, and immune control of viremia.

Ex Vivo Generation of Donor Antigen-Specific Immunomodulatory Cells: A Comparison Study of Anti-CD80/86 mAbs and CTLA4-lg Costimulatory Blockade

Adoptive transfer of alloantigen-specific immunomodulatory cells generated ex vivo with anti-CD80/CD86 mAbs (2D10.4/IT2.2) holds promise for operational tolerance after transplantation. However, good manufacturing practice is required to allow widespread clinical application. Belatacept, a clinically approved cytotoxic T-lymphocyte antigen 4-immunoglobulin that also binds CD80/CD86, could be an alternative agent for 2D10.4/IT2.2. With the goal of generating an optimal cell treatment with clinically approved reagents, we evaluated the donor-specific immunomodulatory effects of belatacept- and 2D10.4/IT2.2-generated immunomodulatory cells. Immunomodulatory cells were generated by coculturing responder human peripheral blood mononuclear cells (PBMCs) (50 × 10⁶ cells) with irradiated donor PBMCs (20 × 10⁶ cells) from eight human leukocyte antigen-mismatched responder–donor pairs in the presence of either 2D10.4/IT2.2 (3 μg/10⁶ cells) or belatacept (40 μg/10⁶ cells). After 14 days of coculture, the frequencies of CD4⁺ T cells, CD8⁺ T cells, and natural killer cells as well as interferon gamma (IFN-γ) production in the 2D10.4/IT2.2- and belatacept-treated groups were lower than those in the control group. The percentage of CD19⁺ B cells was higher in the 2D10.4/IT2.2- and belatacept-treated groups than in the control group. The frequency of CD4⁺CD25⁺CD127^lowFOXP3⁺ T cells increased from 4.1±1.0% (preculture) to 7.1±2.6% and 7.3±2.6% (day 14) in the 2D10.4/IT2.2- and belatacept-treated groups, respectively (p<0.05). Concurrently, delta-2 FOXP3 mRNA expression increased significantly. Compared with cells derived from the no-antibody treated control group, cells generated from both the 2D10.4/IT2.2- and belatacept-treated groups produced lower IFN-γ and higher interleukin-10 levels in response to donor-antigens, as detected by enzyme-linked immunospot. Most importantly, 2D10.4/IT2.2- and belatacept-generated cells effectively impeded the proliferative responses of freshly isolated responder PBMCs against donor-antigens. Our results indicate that belatacept-generated donor-specific immunomodulatory cells possess comparable phenotypes and immunomodulatory efficacies to those generated with 2D10.4/IT2.2. We suggest that belatacept could be used for ex vivo generation of clinical grade alloantigen-specific immunomodulatory cells for tolerance induction after transplantation.

Polysaccharide isolated from seeds of Plantago asiatica L. induces maturation of dendritic cells through MAPK and NF-κB pathway

Plantago species are used as traditional medicine in Asian and Europe. Polysaccharide isolated from the seeds of Plantago asiatica L. could stimulate maturation transformation of bone-marrow derived dendritic cells (DCs). We found that blocking p38, ERK1/2 and JNK MAPK signal transduction could significantly decreased the PLP-2 induced expression of MHC II, CD86 surface molecules on DCs. Blocking p38 and JNK signal also significantly inhibited the cytokine secretion of TNF-α and IL-12p70 as well, while blocking ERK1/2 signal only decreased the secretion of TNF-α. Meanwhile, DCs in the three MAPK signal-blocking groups showed dramatically attenuated effects on stimulating proliferation of T lymphocytes. Similarly, blocking signal transduction of NF-κB pathway also significantly impaired the phenotypic and functional maturation development of DCs induced by PLP-2. These data suggest that MAPK and NF-κB pathway mediates the PLP-induced maturation on DCs. Especially, among the three MAPK pathways, activation of JNK signal transduction is the most important for DCs development after PLP-2 incubation. And PLP-2 may activate the MAPK and NF-κB pathway by triggering toll-like receptor 4 on DCs.

Expansion and Antitumor Cytotoxicity of T-Cells Are Augmented by Substrate-Bound CCL21 and Intercellular Adhesion Molecule 1

Adoptive immunotherapy is based on ex vivo expansion and stimulation of T-cells, followed by their transfer into patients. The need for the ex vivo culturing step provides opportunities for modulating the properties of transferred T-cells, enhancing their antitumor abilities, and increasing their number. Here, we present a synthetic immune niche (SIN) that increases the number and antitumor activity of cytotoxic CD8⁺ T-cells. We first evaluated the effect of various SIN compositions that mimic the physiological microenvironment encountered by T-cells during their activation and expansion in the lymph node. We found that substrates coated with the chemokine CCL21 together with the adhesion molecule intercellular adhesion molecule 1 significantly increase the number of ovalbumin-specific murine CD8⁺ T-cells activated by antigen-loaded dendritic cells or activation microbeads. Notably, cells cultured on these substrates also displayed augmented cytotoxic activity toward ovalbumin-expressing melanoma cells, both in culture and in vivo. This increase in specific cytotoxic activity was associated with a major increase in the cellular levels of the killing-mediator granzyme B. Our results suggest that this SIN may be used for generating T-cells with augmented cytotoxic function, for use in cancer immunotherapy.

Phenotypic and functional analysis of bovine peripheral blood dendritic cells before parturition by a novel purification method

Dendritic cells (DCs) are specialized antigen presenting cells specializing in antigen uptake and processing, and play an important role in the innate and adaptive immune response. A subset of bovine peripheral blood DCs was identified as CD172a⁺/CD11c⁺/MHC (major histocompatibility complex) class II⁺ cells. Although DCs are identified at 0.1%–0.7% of peripheral blood mononuclear cells (PBMC), the phenotype and function of DCs remain poorly understood with regard to maintaining tolerance during the pregnancy. All cattle used in this study were 1 month before parturition. We have established a novel method for the purification of DCs from PBMC using magnetic‐activated cell sorting, and purified the CD172a⁺/CD11c⁺DCs, with high expression of MHC class II and CD40, at 84.8% purity. There were individual differences in the expressions of CD205 and co‐stimulatory molecules CD80 and CD86 on DCs. There were positive correlations between expression of cytokine and co‐stimulatory molecules in DCs, and the DCs maintained their immune tolerance, evidenced by their low expressions of the co‐stimulatory molecules and cytokine production. These results suggest that before parturition a half of DCs may be immature and tend to maintain tolerance based on the low cytokine production, and the other DCs with high co‐stimulatory molecules may already have the ability of modulating the T‐cell linage.

Immune Checkpoint PD-1/PD-L1: Is There Life Beyond Antibodies?

The PD-1/PD-L1 interaction has emerged as a significant target in cancer immunotherapy. Current medications include monoclonal antibodies, which have shown impressive clinical results in the treatment of several types of tumors. The cocrystal structure of human PD-1 and PD-L1 is expected to be a valuable starting point for the design of novel inhibitors, along with the recent crystal structures with monoclonal antibodies, small molecules, and macrocycles.

Gastrointestinal toxicity of immune checkpoint inhibitors: from mechanisms to management

Immune checkpoint inhibitor therapies are a novel group of monoclonal antibodies with proven effectiveness in a wide range of malignancies, including melanoma, renal cell carcinoma, non-small-cell lung cancer, urothelial carcinoma and Hodgkin lymphoma. Their use in a range of other indications, such as gastrointestinal and head and neck cancer, is currently under investigation. The number of agents included in this drug group is increasing, as is their use. Although they have the potential to improve the treatment of advanced malignancies, they are also associated with a substantial risk of immune-related adverse events. The incidence of gastrointestinal toxicity associated with their use is second only in frequency to dermatological toxicity. Thus, gastroenterologists can expect to be increasingly frequently consulted by oncologists as part of a multidisciplinary approach to managing toxicity. Here, we describe this novel group of agents and their mechanisms of action. We review the manifestations of gastrointestinal toxicity associated with their use so that it can be recognized early and diagnosed accurately. We also discuss the proposed mechanisms underlying this toxicity and describe an algorithmic and, wherever possible, evidence-based approach to its management.

Tempo-Spatial Compressed Sensing of Organ-on-a-Chip for Pervasive Health

As a micro-engineered biomimetic system to replicate key functions of living organs, organ-on-a-chip (OC) technology provides a high-throughput model for investigating complex cell interactions with both high temporal and spatial resolutions in biological studies. Typically, microscopy and high-speed video cameras are used for data acquisition, which are expensive and bulky. Recently, compressed sensing (CS) has increasingly attracted attentions due to its extremely low-complexity structure and low sampling rate. However, there is no CS solution tailored for tempo-spatial information acquisition. In this paper, we propose tempo-spatial CS (TS-CS), a unified CS architecture for OC stream, which achieves significant cost reduction and truly combines sensing with compression along the temporal and spatial domains. We point out that TS-CS can consistently achieve better performance by exploiting tempo-spatial compressibility in OC data. To this end, we comprehensively evaluate the system performance by employing four different bases for CS. With comparison to the traditional way, we show that TS-CS always obtains better recovery result with a throughput bound and can achieve around throughput improvement under a reconstruction demand by applying discrete cosine transform matrix as the basis.

An objective in vivo diagnostic method for inflammatory bowel disease

Inflammatory damage to the bowel, as occurs in inflammatory bowel disease (IBD), is debilitating to patients. In both patients and animal experimental models, histological analyses of biopsies and endoscopic examinations are used to evaluate the disease state. However, such measurements often have delays and are invasive, while endoscopy is not quantitatively objective. Therefore, a real-time quantitative method to assess compromised mucosal barrier function is advantageous. We investigated the correlation of in vivo changes in electrical transmural impedance with histological measures of inflammation. Four platinum (Pt) ball electrodes were placed in the lumen of the rat small intestine, with a return electrode under the skin. Electrodes placed within the non-inflamed intestine generated stable impedances during the 3 h testing period. Following an intraluminal injection of 2,4,6-trinitrobenzene sulfonic acid (TNBS), an established animal model of IBD, impedances in the inflamed region significantly decreased relative to a region not exposed to TNBS (p < 0.05). Changes in intestinal transmural impedance were correlated (p < 0.05) with histologically assessed damage to the mucosa and increases in neutrophil, eosinophil and T-cell populations at 3 h compared with tissue from control regions. This quantitative, real-time assay may have application in the diagnosis and clinical management of IBD.

Anti-donor regulatory T cell therapy in liver transplantation

Liver transplantation is accepted as the most reliable therapeutic option for patients with end-stage liver failure, but lifelong administration of immunosuppressive agents continues to be problematic due to various drug-induced morbidities and the risk of mortality. Complete cessation of immunosuppressive drugs while maintaining normal graft function and histology, called operational tolerance, has the potential to overcome these long-standing problems. Previously, we reported the results of a pilot study of anti- donor regulatory T cell therapy in 10 consecutive adult patients who underwent living donor liver transplantation (LDLT), of whom 7 patients successfully stopped immunosuppression for nearly 2 years. Described herein are the clinical follow-ups of these patients, a brief description of the protocol and its theoretical background, and a possible explanation for the immunological findings.

Glycogen Synthase Kinase 3 Inactivation Compensates for the Lack of CD28 in the Priming of CD8+ Cytotoxic T-Cells: Implications for anti-PD-1 Immunotherapy

The rescue of exhausted CD8⁺ cytolytic T-cells (CTLs) by anti-Programmed Cell Death-1 (anti-PD-1) blockade has been found to require CD28 expression. At the same time, we have shown that the inactivation of the serine/threonine kinase glycogen synthase kinase (GSK)-3α/β with small-interfering RNAs (siRNAs) and small molecule inhibitors (SMIs) specifically down-regulates PD-1 expression for enhanced CD8⁺ CTL function and clearance of tumors and viral infections. Despite this, it has been unclear whether the GSK-3α/β pathway accounts for CD28 costimulation of CD8⁺ CTL function. In this article, we show that inactivation of GSK-3α/β through siRNA or by SMIs during priming can substitute CD28 co-stimulation in the potentiation of cytotoxic CD8⁺ CTL function against the EL-4 lymphoma cells expressing OVA peptide. The effect was seen using several structurally distinct GSK-3 SMIs and was accompanied by an increase in Lamp-1 and GZMB expression. Conversely, CD28 crosslinking obviated the need for GSK-3α/β inhibition in its enhancement of CTL function. Our findings support a model where GSK-3 is the central cosignal for CD28 priming of CD8⁺ CTLs in anti-PD-1 immunotherapy.