Research progress of ICOSL/ICOS pathway in maternal-fetal immune tolerance

Co-signaling molecules are molecules whose ligands on the surface of cells interact with receptors on the surface of T cells to convey stimulatory or inhibitory signals to regulate immune responses.Co-signaling molecules play an important role in tumor and autoimmune diseases.Lately,studies have shown that co-signaling molecules are also involved in the regulation of maternal-fetal immune tolerance,and abnormalities of co-signaling molecules may lead to the imbalance of maternal-fetal immune tolerance,resulting in recurrent abortion,eclampsia and other pregnancy complications.ICOSL/ICOS is a ligand and receptor of costimulatory signals,which regulates maternal and fetal immune tolerance by participating in T cell differentiation and Th1 and Th2 cytokine secretion.Therefore,this article reviews the structure of ICOSL/ICOS,the distribution of ICOSL/ICOS at the maternal-fetal interface and its immune regulation during pregnancy,in order to provide new ideas for the future study of immunotherapy of pregnancy complications caused by abnormal co-signaling molecules.

Diverse Roles of Immune Cells in Transplant Rejection and Immune Tolerance

Organ transplant rejection(OTR)is a complex immune reaction involving multiple cells,and it determines graft survival and patient prognosis.At present,most transplant recipients are administered a combination of immunosuppressive and biological agents to protect them from OTR.However,immunosuppressive agents negatively impact the immune system of the patients,causing them to suffer from serious complications,such as chronic infection and malignant tumors.Therefore,a thorough understanding of the mechanisms involved in immune tolerance and immune rejection with regard to organ transplant(OT)is essential for developing better treatment options and improving patient outcomes.This article reviews the role of immune cells in OTR and organ transplant tolerance(OTT),including the novel cell therapies that are currently under clinical trials for transplant recipients.

Ragweed pollen induces allergic conjunctivitis immune tolerance in mice via regulation of the NF-κB signal pathway

AIM:To investigate the feasibility and mechanism of immune tolerance in allergic conjunctivitis.METHODS:The allergic conjunctivitis immune tolerance mice model was established by ragweed pollen(RW)and the related cytokines were detected.The mice were divided into 9 groups and the maslinic acid(MA)or PBS were given for different group after modeling.The expression levels of chemokine ligand 5(CCL5)and P-65 in the conjunctival tissue were analyzed by immunohistochemistry,quantitative reverse transcription polymerase chain reaction(q RT-PCR)and Western blot.The percentage of interleukin-17(IL-17)and CD4+CD25+in the splenocyte supernatant was analyzed by flow cytometry.Fur thermore,the serum and splenocyte supernatant concentration of total-IgE,interleukin-10(IL-10),and IL-17 was analyzed by enzyme linked immune response(ELISA).RESULTS:After the model was established,symptoms of conjunctivitis were alleviated,the level of P-65,CCL5,IL-17,and total-IgE was raised,while the expression of IL-10,CD4+CD25+was decreased.This result fully demonstrated that a typical IL-17/regulatory-T-cells(Treg cells)imbalance and NF-κB activation.When the NF-κB signal pathway was suppressed,it showed that there was a further relief of conjunctivitis in mice.At the same time,the expression of total-IgE,IL-17,and CCL5 was decreased and the expression of anti-inflammatory factor(IL-10,CD4+CD25+)was increased.CONCLUSION:In the state of immune tolerance,symptoms of conjunctivitis in mice are alleviated,the Th-17 cells of allergic conjunctivitis mice are inhibited,and Treg cells activity is enhanced.

Sinomenine promotes differentiation of induced pluripotent stem cells into immature dendritic cells with high induction of immune tolerance

BACKGROUND Immature dendritic cells(imDCs)play an important role in the induction of donor-specific transplant immunotolerance.However,these cells have limitations,such as rapid maturation and a short lifespan in vivo.In previous studies,induced pluripotent stem cells(iPSCs)differentiated into imDCs,and sinomenine(SN)was used to inhibit the maturation of imDCs.AIM To study the capacity of SN to maintain iPSC-derived imDCs(SN-iPSCs-imDCs)in an immature state and the mechanism by which SN-iPSCs-imDCs induce immunotolerance.METHODS In this study,mouse iPSCs were induced to differentiate into imDCs in culture medium without or with SN(iPSCs-imDCs and SN-iPSCs-imDCs).The imDCrelated surface markers,endocytotic capacity of fluorescein isothiocyanate Dextran and apoptosis were analyzed by flow cytometry.The effects of iPSCs-imDCs and SNiPSCs-imDCs on T-cell stimulatory function,and regulatory T(Treg)cell proliferative function in vitro were analyzed by mixed lymphocyte reaction.Cytokine expression was detected by ELISA.The apoptosis-related proteins of iPSCs-DCs and SN-iPSCs-DCs were analyzed by western blotting.The induced immunotolerance of SN-iPSCs-DCs was evaluated by treating recipient Balb/c skin graft mice.Statistical evaluation of graft survival was performed using Kaplan–Meier curves.RESULTS Both iPSCs-imDCs and SN-iPSCs-imDCs were successfully obtained,and their biological characteristics and ability to induce immunotolerance were compared.SN-iPSCs-imDCs exhibited higher CD11c levels and lower CD80 and CD86 levels compared with iPSCs-imDCs.Reduced major histocompatibility complex II expression,worse T-cell stimulatory function,higher Treg cell proliferative function and stronger endocytotic capacity were observed with SN-iPSCs-imDCs(P<0.05).The levels of interleukin(IL)-2,IL-12,interferon-γin SN-iPSCs-imDCs were lower than those in iPSCs-imDCs,whereas IL-10 and transforming growth factor-βlevels were higher(P<0.05).The apoptosis rate of these cells was significantly higher(P<0.05),and the expression levels of cleaved caspase3,Bax and cleaved poly(ADP-ribose)polymerase were higher after treatment with lipopolysaccharides,but Bcl-2 was reduced.In Balb/c mice recipients immunized with iPSCsimDCs or SN-iPSCs-imDCs 7 d before skin grafting,the SN-iPSCs-imDCs group showed lower ability to inhibit donor-specific CD4+T-cell proliferation(P<0.05)and a higher capacity to induce CD4+CD25+FoxP3+Treg cell proliferation in the spleen(P<0.05).The survival span of C57bl/6 skin grafts was significantly prolonged in immunized Balb/c recipients with a donor-specific pattern.CONCLUSION This study demonstrated that SN-iPSCs-imDCs have potential applications in vitro and in vivo for induction of immunotolerance following organ transplantation.

Complex regulatory effects of gut microbial short-chain fatty acids on immune tolerance and autoimmunity

Immune tolerance deletes or suppresses autoreactive lymphocytes and is established at multiple levels during the development,activation and effector phases of T and B cells.These mechanisms are cell-intrinsically programmed and critical in preventing autoimmune diseases.We have witnessed the existence of another type of immune tolerance mechanism that is shaped by lifestyle choices,such as diet,microbiome and microbial metabolites.Short-chain fatty acids(SCFAs)are the most abundant microbial metabolites in the colonic lumen and are mainly produced by the microbial fermentation of prebiotics,such as dietary fiber.This review focuses on the preventive and immunomodulatory effects of SCFAs on autoimmunity.The tissue-and disease-specific effects of dietary fiber,SCFAs and SCFA-producing microbes on major types of autoimmune diseases,including type I diabetes,multiple sclerosis,rheumatoid arthritis and lupus,are discussed.Additionally,their key regulatory mechanisms for lymphocyte development,tissue barrier function,host metabolism,immunity,autoantibody production,and inflammatory effector and regulatory lymphocytes are discussed.The shared and differential effects of SCFAs on different types and stages of autoimmune diseases are discussed.

Mechanisms of Immune Tolerance and Inflammation via Gonadal Steroid Hormones in Preterm Birth

In 2019,preterm births(PTB)accounted for approximately 0.66 million deaths globally.PTB is also associated with a significantly higher risk of mortality and long-term complications for newborns.Long-term studies associated several factors,including disruption of immune tolerance and inflammation,with PTB.However,the pathogenesis of PTB remains unclear.Gonadal steroid hormones are critical for pregnancy maintenance and regulation of immune and inflammatory responses.However,it is not clear how unbalanced gonadal steroid hormones,such as imbalanced estrogen/androgen or estrogen/progesterone contribute to PTB.In this review,we discuss how gonadal steroid hormones mediate dysfunction in immune tolerance and inflammatory responses,which are known to promote the occurrence of PTB,and provide insight into PTB prediction.

Transcriptional and epigenetic regulation of immune tolerance:roles of the NF-κB family members

Immune tolerance is a highly regulated state and involves diverse mechanisms.Central to the induction of tolerance is the targeted modulation of T-cell activities(both effector and regulatory),in which transcription factors play a significant role.The nuclear factor kappa-B(NF-κB)family is a family of transcription factors that not only are critically involved in diverse T-cell responses but also are regulated by many mechanisms to maintain tolerance and T-cell homeostasis.NF-κB,as a transcription factor,has been extensively studied in recent decades,and the molecular mechanisms that regulate NF-κB activities have been well documented.However,recent studies have revealed exciting new roles for NF-κB;in addition to its transcriptional activity,NF-κB can also activate diverse epigenetic mechanisms that mediate extensive chromatin remodeling of target genes to regulate T-cell activities.In this review article,we highlight recent discoveries and emerging opportunities in targeting NF-κB family members as well as their associated chromatin modifiers in the induction of immune tolerance and in the clinical treatment of immune diseases.

Cytokine regulation of immune tolerance

The immune system provides defenses against invading pathogens while maintaining immune tolerance to self-antigens.This immune homeostasis is harmonized by the direct interactions between immune cells and the cytokine environment in which immune cells develop and function.Herein,we discuss three non-redundant paradigms by which cytokines maintain or break immune tolerance.We firstly describe how anti-inflammatory cytokines exert direct inhibitory effects on immune cells to enforce immune tolerance,followed by discussing other cytokines that maintain immune tolerance through inducing CD_(4)^(+) Foxp_(3)^(+) regulatory T cells(Tregs),which negatively control immune cells.Interleukin(IL)-2 is the most potent cytokine in promoting the development and survival of Tregs,thereby mediating immune tolerance.IL-35 is mainly produced by Tregs,but its biology function remains to be defi ned.Finally,we discuss the actions of proinflammatory cytokines that breach immune tolerance and induce autoimmunity,which include IL-7,IL-12,IL-21,and IL-23.Recent genetic studies have revealed the role of these cytokines(or their cognate receptors)in susceptibility to autoimmune diseases.Taken together,we highlight in this review the cytokine regulation of immune tolerance,which will help in further understanding of human diseases that are caused by dysregulated immune system.

Facing challenges with hope:universal immune cells for hematologic malignancies

Many patients have achieved a favorable overall survival rate since allogenic hematopoietic stem cell transplantation(allo-HSCT)has been widely implemented to treat hematologic malignancies.However,graft-versus-host disease(GVHD)and complications of immunosuppressive drugs after allo-HSCT are the main causes of non-relapse mortality and a poor quality of life.In addition,GVHD and infusion-induced toxicity still occur with donor lymphocyte infusions(DLIs)and chimeric antigen receptor(CAR)T-cell therapy.Because of the special immune tolerance characteristics and anti-tumor ability of universal immune cells,universal immune cell therapy may strongly reduce GVHD,while simultaneously reducing tumor burden.Nevertheless,widespread application of universal immune cell therapy is mainly restricted by poor expansion and persistence efficacy.Many strategies have been applied to improve universal immune cell proliferation and persistence efficacy,including the use of universal cell lines,signaling regulation and CAR technology.In this review we have summarized current advances in universal immune cell therapy for hematologic malignancies with a discussion of future perspectives.

Histone methyltransferase Nsd2 ensures maternal-fetal immune tolerance by promoting regulatory T-cell recruitment

Regulatory T cells(Tregs)are fundamentally important for maintaining systemic immune homeostasis and are also required for immune tolerance at the maternal-fetal interface during pregnancy.Recent studies have suggested that epigenetic regulation is critically involved in Treg development and function.However,the role of H3K36me has not yet been investigated.Here,we found that the H3K36me2 methyltransferase Nsd2 was highly expressed in Tregs.Although loss of Nsd2 did not impair systemic Treg development or function,the level of Tregs at the maternal-fetal interface was significantly decreased in pregnant Nsd2 conditional knockout mice.Consequently,maternal-fetal immune tolerance was disrupted in the absence of Nsd2 in Tregs,and the pregnant mice showed severe fetal loss.Mechanistically,Nsd2 was found to upregulate CXCR4 expression via H3K36me2 modification to promote Treg cell recruitment into the decidua and suppress the anti-fetal immune response.Overall,our data identified Nsd2 as a critical epigenetic regulator of Treg recruitment for maternal-fetal tolerance.

Immune tolerance induced by immune-homeostatic particles

Autoimmune diseases,induced by dysfunction of the adaptive immune system,are the common disease categories worldwide.Recently,regulatory T cells(Tregs)enhancing therapies have been demonstrated to treat autoimmune diseases,which could induce immune tolerance to protect cells and tissues from self-attacking of the immune system.However,their widespread application is limited by complex manufacturing process,long production period and high cost.Herein,we give a perspective of immune-homeostatic particles as immune regulators to induce antigen-specific Tregs for treating autoimmune diseases.Disease-specific autoantigen is loaded into the particle to induce Tregs differentiation after release.In addition,the surface of the particles is decorated by specific ligands that could bind and trigger apoptosis of activated T cells,thereby impressing the overreacted immune system.Furthermore,liver sinusoidal endothelial cells(LSEC)-targeting particles are developed to stimulate CD4^(+)T cells differentiation into Tregs.We believe that the immune-homeostatic particles have great potential in autoimmune diseases treatment and are valuable in various immune-related disease treatments.

Immunology demystified: A guide for transplant hepatologists

Liver transplantation has become standard practice for treating end-stage liver disease.The success of the procedure relies on effective immunosuppressive medications to control the host's immune response.Despite the liver's inherent capacity to foster tolerance,the early post-transplant period is marked by significant immune reactivity.To ensure favorable outcomes,it is imperative to identify and manage various rejection types,encompassing T-cell-mediated,antibody-mediated,and chronic rejection.However,the approach to prescribing immunosuppressants relies heavily on clinical judgment rather than evidencebased criteria.Given that the majority of patients will require lifelong immunosuppression as the mechanisms underlying operational tolerance are still being investigated,healthcare providers must possess an understanding of immune responses,rejection mechanisms,and the pathways targeted by immunosuppressive drugs.This knowledge enables customization of treatments and improved patient care,even though a consensus on an optimal immunosuppressive regimen remains elusive.

Hepatitis B:Who should be treated?-managing patients with chronic hepatitis B during the immune-tolerant and immunoactive phases

New hepatitis B virus(HBV)infections are decreasing owing to improved antiviral therapy and increased HBV vaccination worldwide;however,the number of HBV infections remains a major cause of liver carcinogenesis.HBV triggers cytotoxic immunity to eliminate HBV-infected cells.Therefore,the HBV pathophysiology changes in persistently infected individuals depending on host immune responses and HBV DNA proliferation state.To prevent liver cirrhosis and carcinogenesis caused by HBV,it is important to treat HBV infection at an early stage.Active treatment is recommended for the immunoactive hepatitis B surface-antigen-positive and-negative phase,but not during the immune-inactive phase or immune-tolerant phase;instead,follow-up is recommended.However,these patients should be monitored through regular blood tests to accurately diagnose the immune-inactive or-tolerant phases.The treatment regimen should be determined based on the age,sex,family history of liver cancer,and liver fibrosis status of patients.Early treatment is often recommended due to various problems during the immune-tolerant phase.This review compares the four major international practice guidelines,including those from the Japanese Society of Hepatology,and discusses strategies for chronic hepatitis B treatment during the immune-tolerant,immune-inactive,and resolved phases.Finally,recommended hepatitis B antiviral therapy and follow-up protocols are discussed.

Innate and adaptive immune escape mechanisms of hepatitis B virus

Chronic hepatitis B virus(HBV)infection is an international health problem with extremely high mortality and morbidity rates.Although current clinical chronic hepatitis B(CHB)treatment strategies can partly inhibit and eliminate HBV,viral breakthrough may result due to non-adherence to treatment,the emergence of viral resistance,and a long treatment cycle.Persistent CHB infection arises as a consequence of complex interactions between the virus and the host innate and adaptive immune systems.Therefore,understanding the immune escape mechanisms involved in persistent HBV infection is important for designing novel CHB treatment strategies to clear HBV and achieve long-lasting immune control.This review details the immunological and biological characteristics and escape mechanisms of HBV and the novel immune-based therapies that are currently used for treating HBV.

Immunometabolism: A target for the comprehension of immune response toward transplantation

Organ transplantation is a life-saving procedure, however predicting graft survival is still challenging. Understanding immune-cell pathobiology is critical to the development of effective therapies to prevent rejection. Over the recent years it has become progressively evident that the complex nature of immune cell behavioral dynamics is strongly dependent on cellular metabolism, which in turn, relies on competition for nutrients, oxygen and metabolites with other immune cells and microbiota. Furthermore, the influence of the inflammatory state can lead to substantial changes in conditions within the tissue microenvironment. Considering the context of immunity, alterations in metabolic pathways (glycolysis, the tricarboxylic acid cycle, the pentose phosphate pathway, the fatty acid oxidation and synthesis, and the amino acid metabolic pathways) will influence the production of different sets of cytokines and affect transplantation outcome. It is now known that na?ve, resting and effector cells acquire different metabolic profiles and studies have shown that specifically targeting some of these metabolic routes can prevent differentiation of effector T cells in favor of Tregs. Ultimately, to develop effective therapies that will prevent graft loss and understanding how cell metabolism impacts the fate and function of immune cells is now a critical point of discussion. The distinct metabolic features and requirements observed in effector and suppressive cell subsets offer promising opportunities for selective regulation of the immune responses in transplantation and will be discussed in this review.

Cytological evaluation by Caco-2 and KU812 of non-allergenic peptides from simulated digestion of infant formula in vitro

Milk allergy is a common allergic reaction found in infants and young children,most of them appear tolerance after growing up.In this study,infant formula was digested by simulated in vitro digestion method.The potential non-allergenic peptides were further screened from undigested products by exclusion of the known epitopes fromβ-lactoglobulin(BLG)andα-lactalbumin(ALA).These potential non-allergenic peptides were synthesized and their transferability were determined by Caco-2 cell monolayer model.Finally,the potential allergenicity were evaluated by KU812 cell degranulation model.The results showed that 7 peptides were screened as non-allergenic sequences,among which were 3 from ALA and 4 from BLG.The Caco-2 cell model showed that all the synthetic peptides were absorbed and transported well.However,only peptide BLG_(107-118)showed potential allegencity by KU812 model.In conclusion,6 peptides,including ALA_(29-51),ALA_(80-90),ALA_(94-103),BLG_(1-20),BLG_(24-50),and BLG_(123-139)were evaluated as hypoallergenic peptides,which could be used for candidates of peptides inducing immune tolerance for persons with milk allergy.

Islet transplantation-immunological challenges and current perspectives

Pancreatic islet transplantation is a minimally invasive procedure aiming to reverse the effects of insulin deficiency in patients with type 1 diabetes(T1D)by transplanting pancreatic beta cells.Overall,pancreatic islet transplantation has improved to a great extent,and cellular replacement will likely become the mainstay treatment.We review pancreatic islet transplantation as a treatment for T1D and the immunological challenges faced.Published data demonstrated that the time for islet cell transfusion varied between 2 and 10 h.Approximately 54%of the patients gained insulin independence at the end of the first year,while only 20%remained insulin-free at the end of the second year.Eventually,most transplanted patients return to using some form of exogenous insulin within a few years after the transplantation,which imposed the need to improve immunological factors before transplantation.We also discuss the immunosuppressive regimens,apoptotic donor lymphocytes,anti-TIM-1 antibodies,mixed chimerism-based tolerance induction,induction of antigen-specific tolerance utilizing ethylene carbodiimide-fixed splenocytes,pretransplant infusions of donor apoptotic cells,B cell depletion,preconditioning of isolated islets,inducing local immunotolerance,cell encapsulation and immunoisolation,using of biomaterials,immunomodulatory cells,etc.

Liver immunity,autoimmunity,and inborn errors of immunity

The liver is the front line organ of the immune system.The liver contains the largest collection of phagocytic cells in the body that detect both pathogens that enter through the gut and endogenously produced antigens.This is possible by the highly developed differentiation capacity of the liver immune system between self-antigens or non-self-antigens,such as food antigens or pathogens.As an immune active organ,the liver functions as a gatekeeping barrier from the outside world,and it can create a rapid and strong immune response,under unfavorable conditions.However,the liver's assumed immune status is anti-inflammatory or immuno-tolerant.Dynamic interactions between the numerous populations of immune cells in the liver are key for maintaining the delicate balance between immune screening and immune tolerance.The anatomical structure of the liver can facilitate the preparation of lymphocytes,modulate the immune response against hepatotropic pathogens,and contribute to some of its unique immunological properties,particularly its capacity to induce antigen-specific tolerance.Since liver sinusoidal endothelial cell is fenestrated and lacks a basement membrane,circulating lymphocytes can closely contact with antigens,displayed by endothelial cells,Kupffer cells,and dendritic cells while passing through the sinusoids.Loss of immune tolerance,leading to an autoaggressive immune response in the liver,if not controlled,can lead to the induction of autoimmune or autoinflammatory diseases.This review mentions the unique features of liver immunity,and dysregulated immune responses in patients with autoimmune liver diseases who have a close association with inborn errors of immunity have also been the emphases.

Current advances in using tolerogenic dendritic cells as a therapeutic alternative in the treatment of type 1 diabetes

Type 1 diabetes(T1D)is an autoimmune disease characterized by the destruction of insulin-producingβ-cells of the pancreatic islets by autoreactive T cells,leading to high blood glucose levels and severe long-term complications.The typical treatment indicated in T1D is exogenous insulin administration,which controls glucose levels;however,it does not stop the autoimmune process.Various strategies have been implemented aimed at stoppingβ-cell destruction,such as cellular therapy.Dendritic cells(DCs)as an alternative in cellular therapy have gained great interest for autoimmune disease therapy due to their plasticity to acquire immunoregulatory properties both in vivo and in vitro,performing functions such as anti-inflammatory cytokine secretion and suppression of autoreactive lymphocytes,which are dependent of their tolerogenic phenotype,displayed by features such as semimature phenotype,low surface expression of stimulatory molecules to prime T cells,as well as the elevated expression of inhibitory markers.DCs may be obtained and propagated easily in optimal amounts from peripheral blood or bone marrow precursors,such as monocytes or hematopoietic stem cells,respectively;therefore,various protocols have been established for tolerogenic(tol)DCs manufacturing for therapeutic research in the treatment of T1D.In this review,we address the current advances in the use of tolDCs for T1D therapy,encompassing protocols for their manufacturing,the data obtained from preclinical studies carried out,and the status of clinical research evaluating the safety,feasibility,and effectiveness of tolDCs.

Research progress of soluble CD83 in organ transplantation

Organ transplantation is considered to be an effective method for the treatment of end-stage organ failure,early malignant tumors and tissue damage.In order to reduce the rejection of the transplanted organ by the host,immunosuppressive drugs should be used for a long time,but the suppression of the host immune system by immunosuppressive drugs can cause serious side effects.Therefore,how to induce the recipient's immune system to have no response to the transplanted organ after transplantation,while still showing a normal immune response to the alien antigen.Induction of immune tolerance to donor organs has long been a focus of research by transplant scientists.Soluble CD83(sCD83)is a glycoprotein with specific immunosuppressive effects.In recent years,there have been more and more reports on the immune tolerance induced by sCD83 in animal experiments,which has shown a broad prospect in the treatment of host immune rejection after organ transplantation and provided an experimental basis for its clinical transformation.