Induction Of Immune Tolerance Research Articles

The use of Bacillus subtilis as a cost-effective expression system for production of Cholera Toxin B fused factor VIII epitope regions applicable for inducing oral immune tolerance.

Coagulation factor replacement therapy for the X-linked bleeding disorder Haemophilia, characterized by a deficiency of coagulation protein factor VIII (FVIII), is severely complicated by antibody (inhibitors) formation. The development of FVIII inhibitors drastically alters the quality of life of the patients and is associated with a tremendous increase in morbidity as well as treatment costs. The ultimate goal of inhibitor control is antibody elimination. Immune tolerance induction (ITI) is the only clinically established approach for developing antigen-specific tolerance to FVIII. This work aims to establish a novel cost-effective strategy to produce FVIII molecules in fusion with cholera toxin B (CTB) subunit at the N terminus using the Bacillus subtilis expression system for oral tolerance, as the current clinical immune tolerance protocols are expensive. Regions of B-Domain Deleted (BDD)-FVIII that have potential epitopes were identified by employing Bepipred linear epitope prediction; 2 or more epitopes in each domain were combined and cDNA encoding these regions were fused with CTB and cloned in the Bacillus subtilis expression vector pHT43 and expression analysis was carried out. The expressed CTB-fused FVIII epitope domains showed strong binding affinity towards the CTB-receptor GM1 ganglioside. To conclude, Bacillus subtilis expressing FVIII molecules might be a promising candidate for exploring for the induction of oral immune tolerance.

Targeted depletion of PD-1-expressing cells induces immune tolerance through peripheral clonal deletion.

Thymic negative selection of the T cell receptor (TCR) repertoire is essential for establishing self-tolerance and acquired allograft tolerance following organ transplantation. However, it is unclear whether and how peripheral clonal deletion of alloreactive T cells induces transplantation tolerance. Here, we establish that programmed cell death protein 1 (PD-1) is a hallmark of alloreactive T cells and is associated with clonal expansion after alloantigen encounter. Moreover, we found that diphtheria toxin receptor (DTR)-mediated ablation of PD-1+ cells reshaped the TCR repertoire through peripheral clonal deletion of alloreactive T cells and promoted tolerance in mouse transplantation models. In addition, by using PD-1-specific depleting antibodies, we found that antibody-mediated depletion of PD-1+ cells prevented heart transplant rejection and the development of experimental autoimmune encephalomyelitis (EAE) in humanized PD-1 mice. Thus, these data suggest that PD-1 is an attractive target for peripheral clonal deletion and induction of immune tolerance.

Tolerogenic dendritic cell-mediated regulatory T cell differentiation by Chinese herbal formulation attenuates colitis progression

IntroductionUlcerative colitis (UC) is a chronic inflammatory disease characterized by loss of immune tolerance to luminal antigens and progressive intestinal tissue injury. Thus, the re-establishment of immune tolerance is crucial for suppressing aberrant immune responses and UC progression. ObjectivesThis study aimed to investigate the mechanisms underlying the action of CDD-2103 and its bioactive compounds in mediating immune regulation in mouse models of colitis. MethodsTwo experimental colitis models, chronic 2,4,6-trinitrobenzene sulfonic acid (TNBS)- and T-cell transfer-induced Rag1-/- mice, were used to determine the effects of CDD-2103 on colitis progression. Single-cell transcriptome analysis was used to profile the immune landscape and its interactions after CDD-2103 treatment. Liquid chromatography-mass spectrometry (LC-MS) was used to analyze the major components interacting with lymphoid cells. A primary cell co-culture system was used to confirm the effects of bioactive component. ResultsCDD-2103 dose-dependently suppresses the progression of colitis induced by chemicals or T cell transplantation in Rag1-/- mice. The effect of CDD-2103 is primarily attributable to an increase in the de novo generation of regulatory T cells (Tregs) in the lamina propria (LP). Single-cell transcriptomic analysis revealed that CDD-2103 treatment increased the number of tolerogenic dendritic cells (DCs). Mechanistically, CDD-2103 promoted tolerogenic DCs accumulation and function by upregulating several genes in the electron transport chain related to oxidative phosphorylation, leading to increased differentiation of Tregs. Further LC-MS analysis identified several compounds in CDD-2103, particularly those distributed within the mesenteric lymph nodes of mice. Subsequent studies revealed that palmatine and berberine promoted tolerogenic bone marrow-derived dendritic cells (BMDC)-mediated Treg differentiation. ConclusionOverall, our study demonstrated that the clinically beneficial effect of CDD-2103 in the treatment of UC is based on the induction of immune tolerance. In addition, this study supports berberine and palmatine as potential chemical entities in CDD-2103 that modulate immune tolerance.

Extracorporeal photopheresis reduces inflammation and joint damage in a rheumatoid arthritis murine model

BackgroundRheumatoid arthritis (RA) is an autoimmune disease characterized by inflammatory reactions and tissue damage in the joints. Long-term drug use in clinical practice is often accompanied by adverse reactions. Extracorporeal photopheresis (ECP) is an immunomodulatory therapy with few side effects, offering a potential and safe therapeutic alternative for RA through the induction of immune tolerance. This study aimed to investigate the therapeutic effects of ECP on RA using a collagen-induced arthritis (CIA) murine model, as well as to explore its immunomodulatory effects in vivo. Additionally, particular attention was given to the significant role of monocytes during the ECP process.MethodsA murine model of rheumatoid arthritis was established by administering two injections of bovine type II collagen to DBA/1J mice. ECP, ECP-MD (mononuclear cells were depleted during the ECP), MTX, and PBS treatment were applied to the CIA mice. During the treatment process, clinical scores and body weight changes of CIA mice were closely monitored. After six treatment sessions, micro-CT images of the hind paws from live mice were captured. Ankle joints and paws of the mice were collected and processed for histological evaluation. Spleen samples were collected to measure the Th17/Treg cells ratio, and serum samples were collected to assess cytokine and anti-type II collagen IgG levels. Monocytes and dendritic cells populations before and after ECP in vitro were detected by flow cytometry.ResultECP therapy significantly attenuated the progression of CIA, alleviated the severity of clinical symptoms in CIA mice and effectively suppressed synovial hyperplasia, inflammation, and cartilage damage. There was an expansion in the percentage of CD3 + CD4 + CD25 + FoxP3 + Tregs and a decrease in CD3 + CD4 + IL17A + Th17 cells in vivo. Furthermore, ECP reduced the serum levels of pro-inflammatory cytokines IL-6 (53.47 ± 7.074 pg/mL vs 5.142 ± 1.779 pg/mL, P < 0.05) and IL-17A (3.077 ± 0.401 pg/mL vs 0.238 ± 0.082 pg/mlL, P < 0.0001) compared with PBS. Interestingly, the depletion of monocytes during the ECP process did not lead to any improvement in clinical symptoms or histological scores in CIA mice. Moreover, the imbalance in the Th17/Treg cells ratio became even more pronounced, accompanied by an augmented secretion of pro-inflammatory cytokines IL-6 and IL-17A. In vitro, compared with cells without ECP treatment, the proportion of CD11b + cells were significantly reduced (P < 0.01), the proportion of CD11c + cells were significantly elevated (P < 0.001) 24 h after ECP treatment. Additionally, the expression of MHC II (P < 0.0001), CD80 (P < 0.01), and CD86 (P < 0.001) was downregulated in CD11c + cells 24 h after ECP treatment.ConclusionOur study demonstrates that ECP exhibits a therapeutic effect comparable to conventional therapy in CIA mice, and the protective mechanisms of ECP against RA involve Th17/Treg cells ratio, which result in decreased IL-6 and IL-17A. Notably, monocytes derived from CIA mice are an indispensable part to the efficacy of ECP treatment, and the proportion of monocytes decreased and the proportion of tolerogenic dendritic cells increased after ECP treatment in vitro.

Immune tolerance and the prevention of autoimmune diseases essentially depend on thymic tissue homeostasis.

The intricate balance of immune reactions towards invading pathogens and immune tolerance towards self is pivotal in preventing autoimmune diseases, with the thymus playing a central role in establishing and maintaining this equilibrium. The induction of central immune tolerance in the thymus involves the elimination of self-reactive T cells, a mechanism essential for averting autoimmunity. Disruption of the thymic T cell selection mechanisms can lead to the development of autoimmune diseases. In the dynamic microenvironment of the thymus, T cell migration and interactions with thymic stromal cells are critical for the selection processes that ensure self-tolerance. Thymic epithelial cells are particularly significant in this context, presenting self-antigens and inducing the negative selection of autoreactive T cells. Further, the synergistic roles of thymic fibroblasts, B cells, and dendritic cells in antigen presentation, selection and the development of regulatory T cells are pivotal in maintaining immune responses tightly regulated. This review article collates these insights, offering a comprehensive examination of the multifaceted role of thymic tissue homeostasis in the establishment of immune tolerance and its implications in the prevention of autoimmune diseases. Additionally, the developmental pathways of the thymus are explored, highlighting how genetic aberrations can disrupt thymic architecture and function, leading to autoimmune conditions. The impact of infections on immune tolerance is another critical area, with pathogens potentially triggering autoimmunity by altering thymic homeostasis. Overall, this review underscores the integral role of thymic tissue homeostasis in the prevention of autoimmune diseases, discussing insights into potential therapeutic strategies and examining putative avenues for future research on developing thymic-based therapies in treating and preventing autoimmune conditions.

Early life imprinting of intestinal immune tolerance and tissue homeostasis.

Besides its canonical role in protecting the host from pathogens, the immune system plays an arguably equally important role in maintaining tissue homeostasis. Within barrier tissues that interface with the external microenvironment, induction of immune tolerance to innocuous antigens, such as commensal, dietary, and environmental antigens, is key to establishing immune homeostasis. The early postnatal period represents a critical window of opportunity in which parallel development of the tissue, immune cells, and microbiota allows for reciprocal regulation that shapes the long-term immunological tone of the tissue and subsequent risk of immune-mediated diseases. During early infancy, the immune system appears to sacrifice pro-inflammatory functions, prioritizing the establishment of tissue tolerance. In this review, we discuss mechanisms underlying early life windows for intestinal tolerance with a focus on newly identified RORγt+ antigen-presenting cells-Thetis cells-and highlight the role of the intestinal microenvironment in shaping intestinal immune system development and tolerance.

Administration methods and dosage of poly(lactic acid)-glycol intervention to myelin oligodendrocyte glycoprotein-induced experimental autoimmune encephalitis mice

BackgroundMyelin oligodendrocyte glycoprotein-associated disorders (MOGAD) is an autoimmune central nervous system disease. Antigen-specific immune tolerance using nanoparticles such as Polylactic-co-glycolic acid (PLGA) have recently been used as a new therapeutic tolerization approach for CNS autoimmune diseases. We examined whether MOG1-125 conjugated with PLGA could induce MOG-specific immune tolerance in an experimental autoimmune encephalitis (EAE) mouse model. EAE was induced in sixty C57BL/6 J wild-type mice using MOG1-125 peptide with complete Freund’s Adjuvant. The mice were divided into 12 groups (n = 5 each) to test the ability of MOG1-125 conjugated PLGA intervention to mitigate the severity or improve the outcomes from EAE with and without rapamycin compared to antigen alone or PLGA alone. EAE score and serum MOG-IgG titers were compared among the interventions.Kindly check and confirm the processed Affiliation “4” is appropriate.I confirmed the Aff 4.Affiliation: Corresponding author information have been changed to present affiliation. Kindly check and confirm.I checked and confirmed the Corresponding author's information.ResultsMice with EAE that were injected intraperitoneally with MOG1-125 conjugated PLGA + rapamycin complex showed dose-dependent mitigation of EAE score. Intraperitoneal and intravenous administration resulted in similar clinical outcomes, whereas 80% of mice treated with subcutaneous injection had a recurrence of clinical score worsening after approximately 1 week. Although there was no significant difference in EAE scores between unconjugated-PLGA and MOG-conjugated PLGA, serum MOG-IgG tended to decrease in the MOG-conjugated PLGA group compared to controls.ConclusionIntraperitoneal administration of PLGA resulted in dose-dependent and longer-lasting immune tolerance than subcutaneous administration. The induction of immune tolerance using PLGA may represent a future therapeutic option for patients with MOGAD.

Ehf and Fezf2 regulate late medullary thymic epithelial cell and thymic tuft cell development.

Thymic epithelial cells are indispensable for T cell maturation and selection and the induction of central immune tolerance. The self-peptide repertoire expressed by medullary thymic epithelial cells is in part regulated by the transcriptional regulator Aire (Autoimmune regulator) and the transcription factor Fezf2. Due to the high complexity of mTEC maturation stages (i.e., post-Aire, Krt10+ mTECs, and Dclk1+ Tuft mTECs) and the heterogeneity in their gene expression profiles (i.e., mosaic expression patterns), it has been challenging to identify the additional factors complementing the transcriptional regulation. We aimed to identify the transcriptional regulators involved in the regulation of mTEC development and self-peptide expression in an unbiased and genome-wide manner. We used ATAC footprinting analysis as an indirect approach to identify transcription factors involved in the gene expression regulation in mTECs, which we validated by ChIP sequencing. This study identifies Fezf2 as a regulator of the recently described thymic Tuft cells (i.e., Tuft mTECs). Furthermore, we identify that transcriptional regulators of the ELF, ESE, ERF, and PEA3 subfamily of the ETS transcription factor family and members of the Krüppel-like family of transcription factors play a role in the transcriptional regulation of genes involved in late mTEC development and promiscuous gene expression.

A190 HELICOBACTER PYLORI INDUCES AN AUTO-REACTIVE PHENOTYPE IN PINK1 DEFICIENT MICE THAT CORRELATES WITH MOTOR DYSFUNCTION

Abstract Background Parkinson’s disease (PD) is a chronic neurodegenerative disorder. Several genetic predispositions, including the PTEN-induced kinase 1 (PINK1) mutation, have been implicated in early onset family cases. Besides the loss of dopaminergic neurons in the brain, PD patients have a unique immune phenotype that includes increased inflammation, blood serum, brain levels of proinflammatory cytokines, brain infiltration with cytotoxic CD8 T cells, and loss of regulatory T cells (Treg) and their anti-inflammatory phenotype. The role of the gut microbiota and gastrointestinal infections are increasingly recognized as a cofactor in PD. One of pathogens associated with the risk of PD is Helicobacter pylori. The prevalence of this Gram-negative bacteria in PD patients is higher than in the general population and its eradication in PD patients improves motor function. Loss of the PD-associated PINK1 alters induced Treg function in vitro. We previously have shown that in PINK1 knock-out (KO) mice, gut infection with Gram-negative bacteria, Citrobacter rodentium, induces mitochondrial antigen presentation (MitAP) to the CD8 T cells that later infiltrate the brain. In this model, PINK1 KO mice develop a Parkinson-like L-DOPA-responsive motor phenotype after four C. rodentium infections. Aims Here we aimed to scrutinize potential role of the H. pylori infection in the induction of motor dysfunction and disbalanced immune tolerance in PINK1 KO mice. Methods In addition to standard behavioural testing, at 2- and 6-months post-infection we performed a multiplex cytokine analysis of gastric homogenates and spectral flow cytometry of gastric lamina propria, mesenteric lymph nodes, blood, spleen, and brain infiltrating immunocytes. As well as in vitro immunocytes response and function assays to H.pylori exposure in PINK1 KO and wild-type (WT) littermate controls. Results We show that infection with H. pylori causes a long-lasting inflammation in the stomach; and local and systemic immune phenotype that remains 6 months post-infection. This phenotype, though present in some WT infected mice, is higher in PINK1 KOs and similarly to PD patients includes a decrease in Treg proportion, FoxP3 downregulation in regulatory T cells, Gata3+ CD4 T cell loss, as well as increase of circulating mitochondrial antigen-specific CD8 T cells. Moreover, the immune phenotype in the H. pylori infected PINK1 KO mice correlates with motor dysfunction and CD8 T cell brain infiltration with no such association seen in the WT mice. Conclusions These results provide insight to the gut-immunity-brain axis in the pathogenesis of Parkinson’s disease, and further investigate the role of Gram-negative bacteria in the establishment of immune tolerance-autoreactivity balance. Funding Agencies ASAP

Transdermally delivered tolerogenic nanoparticles induced effective immune tolerance for asthma treatment

Induction of antigen-specific immune tolerance for the treatment of allergic or autoimmune diseases is an attractive strategy. Herein, we investigated the protective effect of a transdermal microneedle patch against allergic asthma by stimulating allergen-specific immune tolerance. We fabricated biodegradable tolerogenic nanoparticles (tNPs) that are loaded with a model allergen ovalbumin (OVA) and an immunomodulator rapamycin, and filled the tNPs into microneedle tips by centrifugation to form sustained-release microneedles. After intradermal immunization, the microneedles successfully delivered the cargos into the skin and sustainedly released them for over 96 h. Importantly, the microneedles induced allergen-specific regulatory T cells (Treg), decreased the levels of pro-inflammatory cytokines and antibodies while increased anti-inflammation cytokines, finally leading to restored immune homeostasis. The lung tissue analysis illustrated that the sustained-release microneedles significantly reduced the infiltration of eosinophils, decreased the accumulation of mucus and collagen, and significantly relived asthma symptoms. Our results suggested that the sustained-release microneedle-based transdermal delivery system can induce antigen-specific immune tolerance with improved compliance and efficacy, providing a new therapeutic strategy for the treatment of allergic and autoimmune diseases.

Liver-Targeting Nanoplatforms for the Induction of Immune Tolerance.

Liver-targeting nanoparticles have emerged as a promising platform for the induction of immune tolerance by taking advantage of the liver's unique tolerogenic properties and nanoparticles' physicochemical flexibility. Such an approach provides a versatile solution to the treatment of a diversity of immunologic diseases. In this review, we begin by assessing the design parameters integral to cell-specific targeting and the tolerogenic induction of nanoplatforms engineered to target the four critical immunogenic hepatic cells, including liver sinusoidal epithelial cells (LSECs), Kupffer cells (KCs), hepatic stellate cells (HSCs), and hepatocytes. We also include an overview of multiple therapeutic strategies in which nanoparticles are being studied to treat many allergies and autoimmune disorders. Finally, we explore the challenges of using nanoparticles in this field while highlighting future avenues to expand the therapeutic utility of liver-targeting nanoparticles in autoimmune processes.

Antigen‐specific mRNA lipid nanoparticle platforms for the prevention and treatment of allergy and autoimmune diseases

AbstractWhile most nanomedicines primarily aim to stimulate the immune system against infections or tumors, there is a growing demand for inducing immune tolerance under certain conditions, such as allergic and autoimmune diseases. Researchers have explored nanotechnology‐based strategies to induce immune tolerance in a targeted and specific manner. One approach involves the use of nanoparticles (NPs) to encapsulate immunosuppressive drugs and/or antigens to educate naïve T cells and promote the generation of antigen‐specific regulatory T cells that inhibit immune responses. However, this approach has certain limitations. The hydrophobicity of proteins or peptides restricts the degree to which they can be encapsulated in NPs, which in turn, affects their loading efficiency and treatment efficacy. With the emergence of mRNA lipid nanoparticle (LNP) platforms, there is the possibility of overcoming the limitations of protein and peptide encapsulation. To date, mRNA LNP systems have been shown to provide organ, cellular, and subcellular targeting for the induction of immune tolerance. This method of drug delivery is flexible and scalable that can be customized for a specific patient, resulting in an effective means of administering relevant proteins or epitopes to induce antigen‐specific immune tolerance. With continued research and development, this technology could offer a safer and more effective alternative to current therapies, ultimately improving the quality of life of patients worldwide.

Transdermal Microneedles Alleviated Rheumatoid Arthritis by Inducing Immune Tolerance via Skin-Resident Antigen Presenting Cells.

Restoring immune tolerance is the ultimate goal for rheumatoid arthritis (RA) treatment. The most reported oral or intravenous injection routes for the immunization of autoantigens cause gastrointestinal side effects, low patient compliance, and unsatisfied immune tolerance induction. Herein, the use of a transdermal microneedle patch is for the first time investigated to codeliver CII peptide autoantigen and rapamycin for reversing immune disorders of RA. The immunized microneedles efficiently recruit antigen-presenting cells particularly Langerhans cells, and induce tolerogenic dendritic cells at the administration skin site. The tolerogenic dendritic cells further homing to lymph nodes to activate systemic Treg cell differentiation, which upregulates the expression of anti-inflammatory mediators while inhibiting the polarization of Th1/2 and Th17 T cell phenotypes and the expression of inflammatory profiles. As a result, the optimized microneedles nearly completely eliminate RA symptoms and inflammatory infiltrations. Furthermore, it is demonstrated that a low dose of rapamycin is crucial for the successful induction of immune tolerance. The results indicate that a rationally designed microneedle patch is a promising strategy for immune balance restoration with increased immune tolerance induction efficiency and patient compliance.

Analysis of the Impact of Body Mass Index (BMI) on the Durability of Response in Patients with Aplastic Anemia Treated with Weight-Adjusted Horse Anti-Thymocyte Globulin (hATG)

Introduction: Immunosuppressive therapy (IST) with anti-thymocyte globulin (ATG), cyclosporine A (CsA) and Eltrombopag (Epag) has recently been established as standard of care in adult patients (pts.) with severe (sAA) or very severe (vsAA) aplastic anemia &amp;gt; 40-50 years or ineligible for transplant for other reasons. ATG works via immunosuppressive properties including T-cell depletion and induction of immune tolerance. Horse ATG (hATG) is applied for 4 days with 40 mg/kg/day based on the patient's current body weight. Thus, obese pts., defined by a body mass index (BMI) ≥ 30, receive higher absolute hATG dosages than non-obese pts. (BMI &amp;lt; 30). To date, it is unknown whether increased hATG dosages in obese pts. might have beneficial or adverse effects on AA treatment. To address the role of obesity in AA, we investigated (1) the prevalence of obesity in 334 pts. with (suspected) AA and (2) compared the overall survival (OS) and response of 89 obese and non-obese AA pts. to the treatment with hATG/CsA ±Epag. Methods: Retrospective analysis of data from pts. enrolled in the German Registry for Aplastic Anemia and Bone Marrow Failure (AA-BMF). 334 pts. with (suspected) AA and available BMI data (49% (n=164) male/ 51% (n=170) female, 83% (n=278) BMI &amp;lt; 30, 17% (n=56) BMI ≥ 30) were identified of which 89 pts. (43 male/ 46 female, mean age 50 ± 17 years, 75 BMI &amp;lt; 30/ 14 BMI ≥ 30 at hATG administration) with confirmed diagnosis of AA (4 mAA/ 49 sAA/ 18 vsAA/ 14 AA not otherwise specified/ 4 AA-PNH Overlap) and treatment with hATG/CSA were analyzed in detail. 14 pts. received hATG/CSA/Epag (all BMI &amp;lt; 30). Follow-up data were compiled over 35 ± 38.5 months between 2000 and 2023, whereby follow-up data of 12 pts. were incomplete. Results are given as mean ± standard deviation. Results: Analysis of the age distribution of the 343 pts. with (suspected) AA showed a mean age of 50 ±17 years with a biphasic peak at age approx. 25 and 65 years. The average BMI stratified by age (20-30y: 22.9, 31-40y: 24.5, 41-50y: 26.8, 51-60y: 26.4, 61-70y: 27.5, &amp;gt;70y: 27.8) corresponded to the BMI distribution of the German population surveyed by the German Federal Statistical Office. In accordance with the expected survival rates, the 89 AA pts. treated with hATG/CSA (including 14 pts. with Epag) revealed a 5-year overall survival (OS) of 93%/ 86%/ 67 % at &amp;lt; 40/ 40-60/ &amp;gt; 60 years. Regarding BMI, no significant difference was observed in 5-year OS between obese (BMI ≥ 30, 5y-OS 67%) and non-obese pts. (BMI &amp;lt; 30, 5y-OS 85%, p = 0.51). In pts. responding to IST, hematological response at six months after ATG was reached in 67 % (n=7/11) of the obese and 63 % (n=21/33, in 9 pts. exact timepoint not available) of the non-obese pts. (p = 0.85). The proportion of primary IST refractory pts. was numerically lower in obese (21 %, n=3/14) than in non-obese pts. (32 %, n=21/65, p=0.53). Among all 53 responders (2 pts. had incomplete follow-up to assess relapse), a significantly lower relapse rate of 9 % (n=1/11) in obese (median follow-up: 16 months, range 3 to 120 months) compared to 55 % (n=22/40) in non-obese pts. was observed (median follow-up: 19 months, range 1 to 87 months, p=0.008). Conclusion: BMI distribution of AA pts. by age is comparable to that of the general population with a higher rate of obesity in older pts.. Pts. with a BMI ≥ 30 thus receiving higher ATG dosages do appear to have comparable OS and hematological response rates compared to pts. with BMI &amp;lt;30. However, pending validation in a larger patient cohort, we hypothesize, based on our analysis, that a higher cumulative total ATG dose may have a beneficial impact on relapse rates in pts. with BMI ≥ 30 compared to those with BMI &amp;lt; 30.

USP3 plays a critical role in the induction of innate immune tolerance.

Microbial products, such as lipopolysaccharide (LPS), can elicit efficient innate immune responses against invading pathogens. However, priming with LPS can induce a form of innate immune memory, termed innate immune "tolerance", which blunts subsequent NF-κB signaling. Although epigenetic and transcriptional reprogramming has been shown to play a role in innate immune memory, the involvement of post-translational regulation remains unclear. Here, we report that ubiquitin-specific protease 3 (USP3) participates in establishing "tolerance" innate immune memory through non-transcriptional feedback. Upon NF-κB signaling activation, USP3 is stabilized and exits the nucleus. The cytoplasmic USP3 specifically removes the K63-linked polyubiquitin chains on MyD88, thus negatively regulating TLR/IL1β-induced inflammatory signaling activation. Importantly, cytoplasmic translocation is a prerequisite step for USP3 to deubiquitinate MyD88. Additionally, LPS priming could induce cytoplasmic retention and faster and stronger cytoplasmic translocation of USP3, enabling it to quickly shut down NF-κB signaling upon the second LPS challenge. This work identifies a previously unrecognized post-translational feedback loop in the MyD88-USP3 axis, which is critical for inducing normal "tolerance" innate immune memory.

Abstract 13821: Induction of Immune Tolerance to Intramyocardial Transplantation of Cardiac Progenitor Cells by Regulatory T Lymphocytes

Introduction: The clinical use of human embryonic stem cell (hESCs)-derived cardiac cells is still hampered by rejection which is managed by immunosuppressive drugs and exposes to their side-effects. Hypothesis: We evaluated an alternate strategy based on the induction of immune tolerance by adoptive regulatory T lymphocytes (Treg) transfer. Methods: Human hTreg were isolated from peripheral blood mononuclear cells, expanded for 9 days and phenotyped. Immune-competent mice were then subjected to a myocardial infarction. Three weeks later (baseline), mice with an echocardiographically-measured ejection fraction (EF) ≤50% underwent trans-cutaneous echo-guided peri-infarct injections of 1.4x10 6 hESC-cardiovascular progenitor cells (CPC; n=11) or an equivalent volume of PBS (controls, n=4). Among the CPC-transplanted mice, 6 were intravenously injected with 2x10 6 hTreg at the time of transplantation and 3 days later and 5 only received the vehicle (PBS). Functional and histological end points were assessed 3 weeks after treatments (final) and spleen tissue was processed by flow cytometry for the evaluation of immune cell populations. Results: Three weeks after treatments, all CPC-transplanted hearts had a significantly better preservation of EF [m±SEM], compared with their respective baseline values, than PBS-injected hearts (35.4% ± 5.4% in CPC and 37.5% ± 6.8% in CPC+hTreg vs. -1.3 ± 7.3% in PBS, p=0.004) which was mainly driven by a reduction in LV end-systolic volumes (p=0.004) but only in the hTreg group global longitudinal strain improved by 15.7% ± 13.3% from baseline while it worsened by 36.5% ± 18.8% in their non-hTreg counterparts (p=0.037). Infarct size did not differ among the 3 groups but Treg reduced interstitial fibrosis in remote non infarcted myocardium (0.6% ± 0.1%, p=0.007 vs. CPC-non hTreg and PBS, respectively) and, in spleen tissue, induced significant decreases in CD80+ M1 macrophages (p=0.010) and NKG2D+ NK cells (p=0.013) and an increase in CD206+ M2 macrophages (p=0.004) compared with the other 2 groups. Conclusions: Systemic hTreg administration mitigates adverse heart remodeling by modulating the immune response, potentially facilitating transplantation of hESC-CPC with reduced immunosuppression requirements.

Immune-based, multifaceted inactivation of pathogenic T lymphocytes in treating autoimmune diseases

Immunotherapeutic treatment of autoimmune diseases should aim to inactivate autoaggressive memory T-cells and restore immune tolerance. It is envisaged that three approaches could be used to achieve this goal: stimulation of anti-idiotypic immune responses by vaccination with pathogenic T-cells; administration of suboptimal doses of antibodies (Abs) against two or more surface T-cell markers to provide selective Ab-mediated destruction of activated pathogenic memory T-cells; and induction of oral immune tolerance. The proposal entails the use of T-cell vaccination (TCV) or Ab-based therapy as an initial approach to reduce autoantigenic T-cell sensitization. Subsequently, the implementation of oral immunotherapy (OIT) is recommended to reinstate a consistent immune tolerance.

Tolerogenic dendritic cells generated in vitro using a novel protocol mimicking mucosal tolerance mechanisms represent a potential therapeutic cell platform for induction of immune tolerance.

Dendritic cells (DCs) are mediators between innate and adaptive immunity and vital in initiating and modulating antigen-specific immune responses. The most important site for induction of tolerance is the gut mucosa, where TGF-β, retinoic acid, and aryl hydrocarbon receptors collaborate in DCs to induce a tolerogenic phenotype. To mimic this, a novel combination of compounds - the synthetic aryl hydrocarbon receptor (AhR) agonist IGN-512 together with TGF-β and retinoic acid - was developed to create a platform technology for induction of tolerogenic DCs intended for treatment of several conditions caused by unwanted immune activation. These in vitro-generated cells, designated ItolDCs, are phenotypically characterized by their low expression of co-stimulatory and activating molecules along with high expression of tolerance-associated markers such as ILT3, CD103, and LAP, and a weak pro-inflammatory cytokine profile. When co-cultured with T cells and/or B cells, ItolDC-cultures contain higher frequencies of CD25+Foxp3+ regulatory T cells (Tregs), CD49b+LAG3+ 'type 1 regulatory (Tr1) T cells, and IL-10-producing B cells and are less T cell stimulatory compared to cultures with matured DCs. Factor VIII (FVIII) and tetanus toxoid (TT) were used as model antigens to study ItolDC antigen-loading. ItolDCs can take up FVIII, process, and present FVIII peptides on HLA-DR. By loading both ItolDCs and mDCs with TT, antigen-specific T cell proliferation was observed. Cryo-preserved ItolDCs showed a stable tolerogenic phenotype that was maintained after stimulation with LPS, CD40L, or a pro-inflammatory cocktail. Moreover, exposure to other immune cells did not negatively impact ItolDCs' expression of tolerogenic markers. In summary, a novel protocol was developed supporting the generation of a stable population of human DCs in vitro that exhibited a tolerogenic phenotype with an ability to increase proportions of induced regulatory T and B cells in mixed cultures. This protocol has the potential to constitute the base of a tolDC platform for inducing antigen-specific tolerance in disorders caused by undesired antigen-specific immune cell activation.

Advances in dendritic cell targeting nano-delivery systems for induction of immune tolerance.

Dendritic cells (DCs) are the major specialized antigen-presenting cells (APCs), play a key role in initiating the body's immune response, maintain the balance of immunity. DCs can also induce immune tolerance by rendering effector T cells absent and anergy, and promoting the expansion of regulatory T cells. Induction of tolerogenic DCs has been proved to be a promising strategy for the treatment of autoimmune diseases, organ transplantation, and allergic diseases by various laboratory researches and clinical trials. The development of nano-delivery systems has led to advances in situ modulation of the tolerance phenotype of DCs. By changing the material composition, particle size, zeta-potential, and surface modification of nanoparticles, nanoparticles can be used for the therapeutic payloads targeted delivery to DCs, endowing them with great potential in the induction of immune tolerance. This paper reviews how nano-delivery systems can be modulated for targeted delivery to DCs and induce immune tolerance and reviews their potential in the treatment of autoimmune diseases, organ transplantation, and allergic diseases.

CTH1/TH2 repolarization in induction of immune tolerance to non-steroidal anti-inflammatory drugs during the management of sickle cell disease vaso-occlusive crisis

Respiratory manifestations related to the intake of non-steroidal anti-inflammatory drugs (NSAIDs) during the treatment of the painful vaso-occlusive crisis of sickle cell disease are either a type I hypersensitivity mechanism of the Gell and Coombs classification, or a pharmacological mechanism of NSAIDs. The use of NSAIDs is essential in the Abidjan school because of the absence of therapeutic alternatives in the management of the inflammatory crisis of this disease. The induction of tolerance to NSAIDs initiated by the authors has had clear clinical success. The basic biological reasons for this tolerance were evaluated in this study. A group of 11 sickle cell patients aged 12 to 39 years in whom post-NSAID respiratory manifestations disappeared for at least 6 months following a short tolerance induction protocol with ibuprofen, was assayed by ELISA for TNFα, INFg (Th1 cytokines), IL-4 (Th2 cytokine), IL-10, TGF-β (immunosuppressive cytokines) and total IgE, before induction or pre-induction (D-1) and at day one (D1), D2- 3, one month (M1), and M6 after induction. A repolarization of the Th1/Th2 balance was noted during the post induction period. The high concentration of IL-4 observed at D-1 gradually decreased in favor of the cytokines TNFα, INFg. The decrease in cytokine IL-4 with the level of total IgE was accompanied by the increase of IL-10 and TGF-β demonstrating the regulatory role of these cytokines in the control of allergic diseases. In conclusion, the induction of immuno-tolerance to NSAIDs through a short protocol is well supported by immune regulation. The medium-term effects are real, unlike the results of allergen desensitization or specific immunotherapy. However, this protocol could be used in certain circumstances such as in the case of intolerance to trimethoprim-sulfamethoxazole, used as the treatment of choice for the prevention of opportunistic diseases in people living with human immunodeficiency virus.