Non-self Antigens Research Articles

Principi di immunobiologia del trapianto ed attivazione della risposta immune

To achieve an effective immune response it is important that T cells can recognize a wide variety of non-self antigens; this allows for restrained immune activation and subsequent antigen-specific killing. This task is accomplished through the generation of a repertoire of T cells in a single individual with specificity for an enormous number of potential foreign antigens presented as peptides on the surface of major histocompatibility complex (MHC) molecules. Variations in MHC structure among individuals increase the variety of peptides that can be presented to T cells; this mechanism protects the species as a whole by ensuring adequate T-cell responses to a given foreign organism. Although slightly different, these MHC polymorphisms expressed in the donor kidney are recognized after kidney transplantation between non genetically-identical humans, and induce alloresponses that in the absence of immunosuppression result in rejection of the allograft. In this chapter, we review basic immunological principles important to the field of kidney transplantation.

Emerging roles of metabolites of ω3 and ω6 essential fatty acids in the control of intestinal inflammation.

The gastrointestinal tract is continuously exposed to the external environment, which contains numerous non-self antigens, including food materials and commensal micro-organisms. For the maintenance of mucosal homeostasis, the intestinal epithelial layer and mucosal immune system simultaneously provide the first line of defense against pathogens and are tightly regulated to prevent their induction of inflammatory responses to non-pathogenic antigens. Defects in mucosal homeostasis lead to the development of inflammatory and associated intestinal diseases, such as Crohn’s disease, ulcerative colitis, food allergy and colorectal cancer. The recent discovery of novel dietary ω3 and ω6 lipid-derived metabolites—such as resolvin, protectin, maresin, 17,18-epoxy-eicosatetraenoic acid and microbe-dependent 10-hydroxy-cis-12-octadecenoic acid—and their potent biologic effects on the regulation of inflammation have initiated a new era of nutritional immunology. In this review, we update our understanding of the role of lipid metabolites in intestinal inflammation.

Abstract B142: Activation of endogenous anergic self-specific CD8+ T-cells by polymeric nanoparticles for enhanced cancer immunotherapy

Abstract While the human immune system is often able to protect the body from infectious pathogens, it has multiple mechanisms to inhibit mounting an immune system against what it perceives as “self” and thus often fails to eliminate cancer cells since they seem to have the characteristics of “self.” Our lab found that cytotoxic CD8+ T-cells that recognize self antigens in the peripheral blood of healthy humans were present in frequencies similar to those specific for non-self antigens, but these self-specific CD8+ T-cells are resistant to activation and/or expansion. We hypothesized that tumor-infiltrating CD8+ T-cells recognizing self antigens are often in an anergized state but they could be activated with the appropriate immunostimulatory signals to augment antitumor immunity. Thus, we developed a poly(lactide-co-glycolide) nanoparticle (PLGA NP) based immunostimulatory platform that is surface-functionalized with monoclonal anti-CD28 antibody (Ab), and encapsulated interleukin-2 (IL-2), toll-like receptor-2 (TLR2) agonist and nucleotide-binding oligomerization domain-containing protein 2 (NOD2) in the hydrophobic core. This platform enables the encapsulated immunostimulatory drugs to be continuously released in the tumor microenvironment to activate the tumor infiltrating self-specific CD8+ T-cells in order to enhance antitumor immune response while minimizing the rapid diffusion of these drugs into other parts of the body, greatly reducing the systemic toxicities. Our results demonstrated that the mice bearing melanoma or colon cancers treated with the stimulatory PLGA NP have elicited potent T-cell response, resulting in marked tumor regression and increased overall survival. The developed PLGA NPs are also capable of generating an immunologic memory that prevented tumor growth after rechallenging the survivor mice with the same cancer cell type. Moreover, the developed PLGA NPs can be combined with checkpoint blocking antibodies to achieve the synergistic effect, significantly prolonging the overall survival. We also applied the single-cell TCR sequencing technique to assess both T-cell receptor and phenotypic characteristics of tumor-infiltrating CD8+ T-cells after NP stimulation. The result was further combined with yeast-display libraries of peptide-MHC to identify tumor-specific antigens. Citation Format: Qian Yin. Activation of endogenous anergic self-specific CD8+ T-cells by polymeric nanoparticles for enhanced cancer immunotherapy [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr B142.

Thymic regulatory T cells arise via two distinct developmental programs.

The developmental programs that generate a broad repertoire of regulatory T cells (Treg cells) able to respond to both self antigens and non–self antigens remain unclear. Here we found that mature Treg cells were generated through two distinct developmental programs involving CD25+ Treg cell progenitors (CD25+ TregP) and Foxp3lo Treg cell progenitors (Foxp3lo TregP). The CD25+ TregP had higher rates of apoptosis and interacted with thymic self-antigens with higher affinity than Foxp3lo TregP, and had a T cell antigen receptor (TCR) repertoire and transcriptome distinct from that of Foxp3lo TregP. The development of CD25+ TregP and Foxp3lo TregP was controlled by distinct signaling pathways and enhancers. Transcriptomic and histocytometric data suggested that CD25+ TregP and Foxp3lo TregP arose by coopting negative and positive selection programs, respectively. Treg cells derived from CD25+ TregP, but not Foxp3lo TregP, prevented experimental autoimmune encephalitis. Our findings indicate that Treg cells arise through two distinct developmental programs that are both required for a comprehensive Treg cell repertoire capable of establishing immune tolerance.

An Antigen Space Triangulation Coverage Based Real-Value Negative Selection Algorithm

Negative selection algorithm (NSA) is an important detector generation algorithm of artificial immune system (AIS). Traditional NSAs randomly generate detectors in the whole antigen space without considering the distribution of self/non-self antigens, therefore it is difficult for detectors to cover the whole antigen space evenly and a seriously time-consuming self-tolerance process is required. Aiming at the problem, we proposed a novel NSA based on antigen space triangulation coverage (ASTC) called ASTC-RNSA. In order to avoid the randomness in traditional NSAs, the proposed algorithm employed Delaunay Triangulation method from computational geometry to divide the self space into simplicial cells, which are utilized to determine the detector positions. Then, the overlaps between simplicial cells and self-antigens are removed to form a set of triangulation coverage areas. Finally, immune detectors which only covered non-self antigens space are generated in each triangulation coverage area. After Delaunay triangulation of antigen space, ASTC-RNSA can directly determine sui detector positions and avoid the time-consuming self-tolerance process of traditional NSAs. The analysis result shows that the time complexity of ASTC-RNSA is reduced from traditional exponential level to logarithmic level. The experimental results on several UCI datasets and artificial datasets show that the proposed algorithm can achieve more than 10 times the detector generation efficiency while maintaining similar detection performance with the most widely used representative typical algorithm, V-Detector.

Red Blood Cell Alloimmunization in the Pregnant Patient.

Alloimmunization to red blood cell (RBC) antigens represents a challenge for physicians caring for women of child bearing potential. Exposure to non-self RBC antigens may occur during transfusion or pregnancy leading to the development of antibodies. If a subsequent fetus bears that antigen, maternal antibodies may attack the fetal red blood cells causing red cell destruction and clinically significant hemolytic disease of the fetus and newborn (HDFN). In the most severe cases, HDFN may result in intrauterine fetal demise due to high output cardiac failure, effusions and ascites, known as "hydrops fetalis". This article reviews strategies for management and prevention of RBC alloimmunization in women of child bearing potential.

Autophagy and Rheumatoid Arthritis: Current Knowledges and Future Perspectives.

Autophagy is a degradation mechanism by which cells recycle cytoplasmic components to generate energy. By influencing lymphocyte development, survival, and proliferation, autophagy regulates the immune responses against self and non-self antigens. Deregulation of autophagic pathway has recently been implicated in the pathogenesis of several autoimmune diseases, including rheumatoid arthritis (RA). Indeed, autophagy seems to be involved in the generation of citrullinated peptides, and also in apoptosis resistance in RA. In this review, we summarize the current knowledge on the role of autophagy in RA and discuss the possibility of a clinical application of autophagy modulation in this disease.

Preclinical Development of Oncolytic Immunovirotherapy for Treatment of HPVPOS Cancers

Immunotherapy for HPVPOS malignancies is attractive because well-defined, viral, non-self tumor antigens exist as targets. Several approaches to vaccinate therapeutically against HPV E6 and E7 antigens have been adopted, including viral platforms such as VSV. A major advantage of VSV expressing these antigens is that VSV also acts as an oncolytic virus, leading to direct tumor cell killing and induction of effective anti-E6 and anti-E7 T cell responses. We have also shown that addition of immune adjuvant genes, such as IFNβ, further enhances safety and/or efficacy of VSV-based oncolytic immunovirotherapies. However, multiple designs of the viral vector are possible—with respect to levels of immunogen expression and method of virus attenuation—and optimal designs have not previously been tested head-to-head. Here, we tested three different VSV engineered to express a non-oncogenic HPV16 E7/6 fusion protein for their immunotherapeutic and oncolytic properties. We assessed their profiles of efficacy and toxicity against HPVPOS and HPVNEG murine tumor models and determined the optimal route of administration. Our data show that VSV is an excellent platform for the oncolytic immunovirotherapy of tumors expressing HPV target antigens, combining a balance of efficacy and safety suitable for evaluation in a first-in-human clinical trial.

Abstract 724: A novel heterologous prime boost vaccine system drives tumor specific and potent CD8 T cell responses for cancer immunotherapy

Abstract Tumor-specific neoantigens (TSNAs) are present in a majority of tumor types and are key targets for T cells released by immune checkpoint blockade therapy. Given that TSNAs are non-self antigens, they are particularly attractive cancer vaccine targets. We have developed a potent heterologous prime/boost immunization approach to deliver predicted TSNAs to patients, which is comprised of a replication incompetent chimpanzee adenoviral vector (ChAdV) for the prime vaccination and a self-replicating, synthetic viral vector (srRNA) for repeated boost vaccinations. The ChAdV vector is similar in design to other adenoviral vectors that have demonstrated induction of high titer, polyfunctional and durable CD4 and CD8 T-cell responses against non-self antigens that protected humans against infections. The srRNA vector is based on Venezuelan equine encephalitis virus (VEE), where sequences encoding the structural proteins of VEE were deleted and replaced by a TSNA expression cassette. For delivery in vivo, the srRNA is formulated with a lipid nanoparticle (LNP), which facilitates efficient cellular uptake of the RNA and enhances antigen expression as well as the resulting immune response. We demonstrate that the srRNA vector effectively replicates in vitro and in vivo resulting in durable and high levels of antigen expression. To characterize the vectors in pre-clinical animal models, a prototypical expression cassette that encodes multiple mouse MHC class I tumor antigens as well as Mamu-A01 restricted class I antigens for monitoring immune responses in mice and non-human primates (NHPs) was introduced into both vector systems. We demonstrate that immunization of mice with either vector results in strong antigen-specific CD8 T-cell responses against the encoded murine epitopes. The heterologous prime/boost approach provided a statistically significant survival advantage to tumor bearing mice when compared to untreated mice. The potency of the immunization platform was also assessed in Indian rhesus macaques and the platform demonstrated a quick onset of T-cell responses 1 week post ChAdV prime vaccination with peak T-cell responses against all delivered Mamu-A01 restricted class I antigens at 2-3 weeks. Such ChAdV primed T-cell responses were effectively boosted by the LNP formulated srRNA vector. Co-administration of anti-CTLA4 with the vaccine demonstrated enhanced vaccine induced immune response. These data demonstrate that the heterologous prime/boost platform effectively programs robust T-cell immunity toward encoded non-self antigens in NHPs, which is a highly predictive model of vaccine responses in humans. This vaccine platform is targeted for entry into clinical trials in mid 2018. Citation Format: Wade Blair, Gijsbert Grotenbreg, Ciaran Scallan, Amy Rappaport, Renee Greer, Leonid Gitlin, Kieu Lam, James Heyes, Anne Van Abbema, Hadley Hanson, Petra Schreiner, karin Jooss. A novel heterologous prime boost vaccine system drives tumor specific and potent CD8 T cell responses for cancer immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 724.

Four-Dimensional Imaging of T Cells in Kidney Transplant Rejection.

Kidney transplantation is the treatment of choice for ESRD but is complicated by the response of the recipient's immune system to nonself histocompatibility antigens on the graft, resulting in rejection. Multiphoton intravital microscopy, referred to as four-dimensional imaging because it records dynamic events in three-dimensional tissue volumes, has emerged as a powerful tool to study immunologic processes in living animals. Here, we will review advances in understanding the complex mechanisms of T cell-mediated rejection made possible by four-dimensional imaging of mouse renal allografts. We will summarize recent data showing that activated (effector) T cell migration to the graft is driven by cognate antigen presented by dendritic cells that surround and penetrate peritubular capillaries, and that T cell-dendritic cell interactions persist in the graft over time, maintaining the immune response in the tissue.

Complimentary mechanisms of dual checkpoint blockade expand unique T-cell repertoires and activate adaptive anti-tumor immunity in triple-negative breast tumors

ABSTRACTTriple-negative breast cancer (TNBC) is an aggressive and molecularly diverse breast cancer subtype typified by the presence of p53 mutations (∼80%), elevated immune gene signatures and neoantigen expression, as well as the presence of tumor infiltrating lymphocytes (TILs). As these factors are hypothesized to be strong immunologic prerequisites for the use of immune checkpoint blockade (ICB) antibodies, multiple clinical trials testing single ICBs have advanced to Phase III, with early indications of heterogeneous response rates of <20% to anti-PD1 and anti-PDL1 ICB. While promising, these modest response rates highlight the need for mechanistic studies to understand how different ICBs function, how their combination impacts functionality and efficacy, as well as what immunologic parameters predict efficacy to different ICBs regimens in TNBC. To address these issues, we tested anti-PD1 and anti-CTLA4 in multiple models of TNBC and found that their combination profoundly enhanced the efficacy of either treatment alone. We demonstrate that this efficacy is due to anti-CTLA4-driven expansion of an individually unique T-cell receptor (TCR) repertoire whose functionality is enhanced by both intratumoral Treg suppression and anti-PD1 blockade of tumor expressed PDL1. Notably, the individuality of the TCR repertoire was observed regardless of whether the tumor cells expressed a nonself antigen (ovalbumin) or if tumor-specific transgenic T-cells were transferred prior to sequencing. However, responsiveness was strongly correlated with systemic measures of tumor-specific T-cell and B-cell responses, which along with systemic assessment of TCR expansion, may serve as the most useful predictors for clinical responsiveness in future clinical trials of TNBC utilizing anti-PD1/anti-CTLA4 ICB.

A collaborative detection approach for internal steam leakage of tyre vulcanization workshop with artificial immune algorithm

In manufacturing industry, internal leakage of steam trap usually results in great steam waste. In particular, internal steam leakage in tyre vulcanization workshop has significant influences on its production safety and energy efficiency. In practice, internal steam leakage problem often is ignored and it tends to be difficult to detect this leakage due to lack of comprehensive flow meter or method. This paper presents a collaborative detection method for this problem in tyre vulcanization workshop with artificial immune algorithm. In the method, internal leakage of steam trap is defined as nonself antigens, and steam pressure differentials between steam pipe and steam rooms (or bladders) are extracted as epitopes of antigens. Furthermore, periodic energy efficiency and steam pressure of vulcanizer as the danger signals are simultaneously detected. Energy efficiency is represented by damaged cells which will be identified firstly for locating the leaking steam straps through antibodies. Furthermore, the self-adaptive danger thresholds for energy efficiency are evaluated through a steam consumption model and the Levenberg–Marquardt back propagation algorithm. An immune-based clustering algorithm aiNet is then adopted to generate antibodies (detectors) for detection on the steam pressure of vulcanizer. Finally, a case study is implemented to validate this method, which shows that collaborative detection method allows locating the specific leaking steam trap and is a feasible tool to reduce steam waste and ensure the safety of steam supply.

Transfusion Support of Minority Patients: Extended Antigen Donor Typing and Recruitment of Minority Blood Donors

One of the most important and persistent complications of blood transfusion is red blood cell (RBC) alloimmunization. When a patient is exposed to RBC antigens that differ from their own they can form alloantibodies to these foreign antigens. Blood group antigens are highly conserved and follow ancestral patterns of inheritance that may demonstrate population restriction. Minority populations who require chronic transfusion are at particularly high risk of alloimmunization when the blood donor population does not share the same ancestral background, resulting in exposure to non-self RBC antigens. It is incumbent on blood collectors to support patients with risk factors for alloimmunization as well as patients who have already formed alloantibodies. Increasing utilization of RBC genotyping may represent an opportunity to improve access to RBC units from donors that match the extended RBC phenotype of all possible patients.

Neoantigen Vaccines Pass the Immunogenicity Test

Neoantigens arising from tumor-specific genomic alterations constitute authentic non-self antigens and represent a new class of targets for cancer immunotherapy. Recent reports on various vaccine platforms targeting neoantigens suggest a basis for precision therapies customized to each patient's tumor mutational profile.

A PEGylated hyaluronic acid conjugate for targeted cancer immunotherapy

The cell-free approach to foreignizing tumor cells with non-self antigens has received increasing attention as a method to induce cytotoxic T lymphocyte (CTL)-mediated immunological rejection of tumors, because the clinical translation of the conventional CTL-based cancer immunotherapies has been limited by a complicated manufacturing process and autotransplantation. In this study, we prepared matrix metalloproteinase 9 (MMP9)-responsive polymeric conjugates consisting of PEGylated hyaluronic acid (HA) as the targeting moiety and ovalbumin (OVA) as the model foreign antigen. The MMP9-cleavable linker was introduced between PEG and the HA backbone to facilitate the detachment of the PEG corona from the conjugate at the tumor site. From the in vitro cellular uptake study, it was revealed that the conjugate was effectively taken up by the CD44-expressing TC-1 cancer cells in the presence of MMP9 via receptor-mediated endocytosis. When the conjugate was systemically administered into the tumor-bearing mice with endogenous OVA-specific CTLs, the tumor growth was markedly inhibited, which was attributed to the significant antigen presentation on the tumor cells. Overall, the MMP9-responsive conjugates bearing foreign antigens might have the potential as an alternative to CTL-based cancer immunotherapeutics.

IDO1 activity in selected immune cells controls antibody responses

Abstract Indoleamine 2,3-dioxygenase 1 (IDO1) is an enzyme involved in the initial step of tryptophan degradation along the kynurenine pathway. It has immunosuppressive effects, linked to enzymic and non-enzymic regulatory functions. IDO1 is also crucial for sustaining the function of T regulatory cells (Treg), which are involved in the establishment of peripheral tolerance. We recently found that defective IDO1 induction is associated to anti-FVIII antibody production in patients with severe Hemophilia A1. In hemophilic mice, CpG- rich oligodeoxynucleotides (CpG-ODN) administration induced IDO1 expression in dendritic cells (DCs) that control FVIII antibody response. Recently we discovered that CpG-ODN selectively induced IDO1 in a subset of conventional DCs (cDCs). IDO1 was found to be highly expressed in gut CD11C+CD103+ DCs, which are required for establishment of oral tolerance2. Based on these data we analyzed the impact of IDO1 deficiency in controlling antibody responses, in two different experimental models (FVIII and ovalbumin, OVA, immunization). Interestingly, IDO1 deficiency resulted in a significant increase of FVIII-specific antibody production relative to wild type controls. Similarly, IDO KO mice showed a significant immunoglobulin production in a model of OVA-induced oral tolerance. These data suggest the regulatory role of IDO1 in controlling antibody responses to self and non-self antigens.

Zebrafish FOXP3 is required for the maintenance of immune tolerance

Regulatory T (Treg) cells play a central role in the suppression of excessive immune responses against both self and non-self antigens. The development and function of Treg cells are controlled by a master regulatory gene encoding the forkhead box P3 (FOXP3) protein in mammals. However, little is known regarding the functions of Treg cells and FOXP3 in non-mammalian vertebrates. In this study, we generated mutant zebrafish lacking a functional FOXP3 ortholog, and demonstrated a significant reduction in survival accompanied by a marked increase in inflammatory gene expression, mononuclear cell infiltration, and T cell proliferation in peripheral tissues. Our findings indicate that the zebrafish FOXP3 protein may have an evolutionally conserved role in the control of immune tolerance, illuminating the potential of the zebrafish as a novel model for investigating the development and functions of Treg cells.

Disruption of Transplant Tolerance by an "Incognito" Form of CD8 T Cell-Dependent Memory.

Several approaches successfully achieve allograft tolerance in preclinical models but are challenging to translate into clinical practice. Many clinically relevant factors can attenuate allograft tolerance induction, including intrinsic genetic resistance, peritransplant infection, inflammation, and preexisting antidonor immunity. The prevailing view for immune memory as a tolerance barrier is that the host harbors memory cells that spontaneously cross-react to donor MHC antigens. Such preexisting "heterologous" memory cells have direct reactivity to donor cells and resist most tolerance regimens. In this study, we developed a model system to determine if an alternative form of immune memory could also block tolerance. We posited that host memory T cells could potentially respond to donor-derived non-MHC antigens, such as latent viral antigens or autoantigens, to which the host is immune. Results show that immunity to a model nonself antigen, ovalbumin (OVA), can dramatically disrupt tolerance despite undetectable initial reactivity to donor MHC antigens. Importantly, this blockade of tolerance was CD8+ T cell-dependent and required linked antigen presentation of alloantigens with the test OVA antigen. As such, this pathway represents an unapparent, or "incognito," form of immunity that is sufficient to prevent tolerance and that can be an unforeseen additional immune barrier to clinical transplant tolerance.

Can killers be saviors?

Autoimmunity and cancer have a multifarious epidemiology. Often, it is because of an impaired genome, culminating in functional aberrations in the human system. Systemic lupus erythematosus (SLE) is a heterogeneous complex disease which ensues due to the failure of the immune system to distinguish between self and non-self antigens, thus producing autoantibodies against DNA, RNA and proteins. Cancer, the other side of the same coin, results from an excessive proliferation of cells that evade immune regulation as a result of incompetent defense by T-cells, B-cells and macrophages. Recent findings have indicated that lupus autoantibodies could be used as an effective weapon to kill cancerous cells. This is an attempt to take an account of malicious 'lupus autoantibodies' and their role in neutralizing cancerous cells which may help in enhancing the survival rate of cancer patients, hence, killers can be saviors.

Can the Immune System Perform a t-Test?

The self-nonself discrimination hypothesis remains a landmark concept in immunology. It proposes that tolerance breaks down in the presence of nonself antigens. In strike contrast, in statistics, occurrence of nonself elements in a sample (i.e., outliers) is not obligatory to violate the null hypothesis. Very often, what is crucial is the combination of (self) elements in a sample. The two views on how to detect a change seem challengingly different and it could seem difficult to conceive how immunological cellular interactions could trigger responses with a precision comparable to some statistical tests. Here it is shown that frustrated cellular interactions reconcile the two views within a plausible immunological setting. It is proposed that the adaptive immune system can be promptly activated either when nonself ligands are detected or self-ligands occur in abnormal combinations. In particular we show that cellular populations behaving in this way could perform location statistical tests, with performances comparable to t or KS tests, or even more general data mining tests such as support vector machines or random forests. In more general terms, this work claims that plausible immunological models should provide accurate detection mechanisms for host protection and, furthermore, that investigation on mechanisms leading to improved detection in “in silico” models can help unveil how the real immune system works.