Tumor-infiltrating T-Lymphocyte immunity-related immune tolerance and anti–programmed cell death protein 1/ligand of programmed cell death protein 1 therapy for advanced hepatocellular carcinoma

Systemic therapy has become the standard treatment for patients with advanced hepatocellular carcinoma(HCC)whose treatment options are limited.However,the long-term patient response to drugs and the survival outcomes remain a concern.With increasing exploration of the HCC microenvironment,particularly in terms of T lymphocyte immunity,a new era of immunomolecular targeted therapy,based on molecular signaling,has arrived for advanced HCC.In the study of immune tolerance of the intrinsic HCC microenvironment,we found that multiple immunosuppressive mechanisms and immune checkpoint inhibitors,such as anti–programmed cell death protein 1/ligand of programmed cell death protein 1 therapy,have improved clinical outcomes in some patients with advanced HCC.Furthermore,various combination therapies have been investigated,and HCC types have been categorized into different types based on anti–programmed cell death protein 1(PD-1)/ligand of programmed cell death protein 1(PD-L1)treatment.In this paper,we first discuss the tumor-infiltrating T lymphocyte immunity and immune tolerance of HCC.We then clarify the basic mechanism of anti–PD-1/PD-L1 therapy and discuss the types of HCC based on anti–PD-1/PD-L1 therapy.Thereafter,we explain the relevant studies and mechanisms of combination therapy of anti–PD-1/PD-L1 with antiangiogenesis drugs or multikinase kinase inhibitors,anti–T lymphocyte–related signaling pathways in HCC,and other anti-CD8+T cell immune checkpoints.In this way,this review offers a deeper understanding of anti–PD-1/PD-L1 immunotherapy for advanced HCC,in order to provide better individualized treatments for patients with advanced HCC.

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.

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.

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.

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.

IMMUNE TOLERANCE INDUCED BY GAMMA-RAY IRRADIATION

Objective: To detect the existence of immune tolerance induced by gamma-ray irradiation. Methods: Peritoneal cells were harvested from mice subjected to 5 Gy 60Co gamma-ray total body irradiation at 3d, 7d, 15d and 30d, then their counts, morphological changes and IL-12 gene expression were investigated. Results: After irradiation, the peritoneal cells were sharply reduced, the cell morphology shifted from round-like to polymorphic and fusiform with some processes, expression of IL-12 p35 was seriously suppressed, while that of IL-12 p40 greatly enhanced. Conclusion: Our data highly suggest that the gamma-ray irradiation could potentially induce dendritic cell (DC) commitment and immune tolerance.

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.

Gastric cancer liver metastasis will reduce the efficacy of immunotherapy

Immune checkpoint inhibitors augment the antitumor activity of T cells by inhibiting the negative regulatory pathway of T cells,leading to notable efficacy in patients with non-small cell lung cancer,melanoma,and other malignancies through immunotherapy utilization.However,secondary malignant liver tumors not only lower the liver's sensitivity to immunotherapy but also trigger systemic immune suppression,resulting in reduced overall effectiveness of immune therapy.Patients receiving immunotherapy for non-small cell lung cancer and melanoma experience reduced response rates,progression-free survival,and overall survival when secondary malignant tumors develop in the liver.Through Liu's retrospective analysis,valuable insights are provided for the future clinical management of these patients.Therefore,in patients with gastric cancer(GC),the occurrence of liver metastasis might be indicative of reduced efficacy of immuno-therapy.Overcoming liver immune tolerance mechanisms and their negative impacts allows for the potential benefits of immunotherapy in patients with GC and liver metastasis.INTRODUCTION Gastric cancer(GC)ranks among the prevalent malignancies affecting the digestive system globally.Based on the latest epidemiological data[1,2],it holds the fifth position for incidence and the fourth position for mortality among all malignant tumors.GC cases and fatalities in China make up roughly half of the worldwide figures.Earlier investigations[3]have demonstrated that the median overall survival(mOS)among advanced GC patients left untreated typically ranges from 3 to 4 months.Systemic chemotherapy recipients often experience a mOS of around one year,accompanied by a marked improvement in the quality of life among patients with advanced GC.The mainstay of treatment for advanced GC patients involves chemotherapeutic medications such as fluoropyrimidines,platinum compounds,and taxanes.However,their efficacy in tumor control is constrained by acquired resistance and primary resistance.The rise of personalized precision therapy has propelled immunotherapy into the spotlight as a crucial component of comprehensive treatment[4].By blocking the negative regulatory pathways of T cells,immune checkpoint inhibitors(ICIs)boost the anti-tumor effect of T cells.Immunotherapy has brought about significant therapeutic benefits for patients diagnosed with non-small cell lung cancer,melanoma,and related illnesses[5,6],instilling newfound hope in those with advanced GC[7].However,phase III clinical trial data[8-12]reveals that the incorporation of immunotherapy into chemotherapy regimens improves overall survival(OS)outcomes for patients with advanced GC.The liver's immune-exempt nature renders it less responsive to immunotherapy when secondary malignant tumors are present,fostering systemic immune suppression and yielding unfavorable outcomes in immune therapy[13-15].In retrospective research[16-20]pertaining to non-small cell lung cancer and melanoma,it has been observed that the presence of secondary liver malignancies may lower the response rate,progression-free survival(PFS),and OS rates in patients treated with immunotherapy,independent of factors such as tumor mutation burden and PD-L1 expression.Despite this,there is a paucity of studies examining whether the existence of secondary malignant liver tumors affects the effectiveness of immunotherapy in patients diagnosed with advanced HER-2 negative GC.

Role of maternal-fetal immune tolerance in the establishment and maintenance of pregnancy

Normal pregnancy is a contradictory and complicated physiological process.Although the fetus carries the human leukocyte antigen(HLA)inherited from the paternal line,it does not cause maternal immune rejection.As the only exception to immunological principles,maternal-fetal immune tolerance has been a reproductive immunology focus.In early pregnancy,fetal extravillous trophoblast cells(EVTs)invade decidual tissues and come into direct contact with maternal decidual immune cells(DICs)and decidual stromal cells(DSCs)to establish a sophisticated maternal-fetal crosstalk.This study reviews previous research results and focuses on the establishment and maintenance mechanism of maternal-fetal tolerance based on maternal-fetal crosstalk.Insights into maternal-fetal tolerance will not only improve understanding of normal pregnancy but will also contribute to novel therapeutic strategies for recurrent spontaneous abortion,pre-eclampsia,and premature birth.

Low-dose immune tolerance induction for severe hemophilia A inhibitor patients:Immunosuppressants are generally not necessary for inhibitor-titer below 200 BU/mL

Importance:It remained unclear that the efficacy comparison between low-dose immune tolerance induction(LD-ITI)incorporating immunosuppressants(IS)when severe hemophilia A(SHA)patients had inhibitor-titer≥200 Bethesda Units(BU)/mL(LD-ITI-IS^(200) regimen)and LD-ITI combining with IS when SHA patients had inhibitor-titer≥40 BU/mL(LD-ITI-IS^(40) regimen).Objective:To compare the efficacy of the LD-ITI-IS^(200) regimen with that of the LD-ITI-IS^(40) regimen for SHA patients with high-titer inhibitors.Methods:A prospective cohort study on patients receiving LD-ITI-IS^(200) compared to those receiving LD-ITI-IS^(40) from January 2021 to December 2023.Both received LD-ITI[FVIII 50 IU/kg every other day].IS(rituximab+prednisone)was added when peak inhibitor tier≥200 BU/mL in the LD-ITI-IS^(200) regimen and≥40 BU/mL in the LD-ITI-IS^(40) regimen.Success is defined as a negative inhibitor plus FVIII recovery≥66%of the expected.Results:We enrolled 30 patients on LD-ITI-IS^(200) and 64 patients on LD-ITI-IS^(40),with similar baseline clinical characteristics.A lower IS-use rate was discovered in the LD-ITI-IS^(200) regimen compared to the LD-ITI-IS^(40) regimen(30.0%vs.62.5%).The two regimens(LD-ITI-IS^(200) vs.LD-ITI-IS^(40))had similar success rate(70.0%vs.79.7%),median time to success(9.4 vs.10.6 months),and annualized bleeding rate during ITI(3.7 vs.2.8).The cost to success was lower for LD-ITI-IS^(200) than for LD-ITI-IS^(40)(2107 vs.3256 US Dollar/kg).Among patients with peak inhibitor-titer 40-199 BU/mL,10 non-IS-using(on LD-ITI-IS^(200) regimen)and 28 IS-using(on LD-ITI-IS^(40) regimen)had similar success rates(70.0%vs.78.6%)and time to success(9.0 vs.8.8 months).Interpretation:In LD-ITI,IS are not necessary for inhibitor titer<200 BU/mL.

Consideration on immunotherapy of liver metastases of malignant tumors

In this editorial,we comment on the article“Analysis of the impact of immuno-therapy efficacy and safety in patients with gastric cancer and liver metastasis”by Liu et al that was published in the recent issue of the World Journal of Gastroin-testinal Surgery.It has prompted us to think and summarize some thoughts on immunotherapy for malignant tumor liver metastasis.Immunotherapy plays a crucial role in the treatment of malignant tumors;however,the presence of liver metastases in advanced tumors may impact its efficacy.Although patients with liver metastases can still benefit from immunotherapy,multiple clinical studies have indicated that,compared to other sites of metastasis,liver metastases may diminish the effectiveness of immunotherapy.The efficacy of immune checkpoint inhibitors in patients with liver metastases often fails to reach the ideal level,primarily due to the liver metastases exploiting the host's peripheral immune to-lerance mechanisms to promote systemic CD8(+)T cell exhaustion,resulting in a systemic immune-tolerant environment.This article aims to summarize the reasons for the decreased efficacy of immunotherapy following liver metastasis in various malignant tumors and propose potential clinical strategies for manage-ment.

Impact of liver metastasis on immunotherapy in gastric carcinoma

The editorial discusses the impact of liver metastasis on immunotherapy efficacy in gastric cancer(GC)patients.Liver metastasis can hinder the effectiveness of immunotherapy by altering the immune microenvironment,leading to systemic loss of T-cells and reduced treatment response.Studies suggest that liver meta-stases serve as a negative baseline factor for immunotherapy efficacy,resulting in poorer progression-free survival and objective response rates.Strategies such as liver-mediated radiotherapy may help improve treatment outcomes by reshaping the liver’s immune microenvironment and reducing T-cell depletion.Understand-ing the complex interplay between liver metastasis and immunotherapy response is crucial for optimising patient care in GC.

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.

Establishment of Nasal Tolerance to Heat Shock Protein-60 Alleviates Atherosclerosis by Inducing TGF-β-dependent Regulatory T Cells

Mounting evidence supports that a newly identified regulatory T cell (Treg),CD4+LAP+ Treg,is associated with oral tolerance induction and following inhibition of atherosclerosis,but little is described about whether nasal tolerance to antigen likewise induces the novel Tregs production and the relevant antiatherosclerotic benefit.We investigated the effect of nasal administration of heat shock protein-60 (HSP60) on atherogenesis.HSP60 or phosphate buffer solution (PBS) was nasally adminis-tered to six-week-old male ApoE-/-mice.At the 10th week after the nasal administration,there was a significant decrease in atherosclerotic plaque areas of aortic roots in the HSP60-treated mice as com-pared with those in the PBS-treated mice.Atherosclerosis suppression was accompanied with a signifi-cant increase in CD4+LAP+ and CD4+CD25+Foxp3+ Tregs and a concurrently increased production of TGF-β in the HSP60-treated mice.The protective effect of HSP60 was offset by injection of anti-TGF-βantibody.It is concluded that nasal administration of HSP60 can inhibit atherosclerotic formation through immune tolerance which is established by Tregs depending on the induction of anti-inflammatory cytokine TGF-β.Immune tolerance induced by nasal administration of HSP60 may provide an alternative therapeutic method for atherosclerosis.

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.

Clinical operational tolerance in liver transplantation:state-of-the-art perspective and future prospects

BACKGROUND:Liver transplantation is the definite treatment for end-stage liver diseases with satisfactory results.However,untoward effects of life-long immunosuppression prevent the development of alternative strategies to achieve better longterm outcome.Achieving clinical operational tolerance is the ultimate goal.DATA SOURCES:A PubMed and Google Scholar search using terms:"immune tolerance","liver transplantation","clinical trial","operational tolerance" and "immunosuppression withdrawal" was performed,and relevant articles published in English in the past decade were reviewed.Full-text publications relevant to the field were selected and relevant articles from reference lists were also included.Priority was given to those articles which are relevant to the review.RESULTS:Because of the inherent tolerogenic property,around 20%-30% of liver transplantation recipients develop spontaneous operational tolerance after immunosuppression withdrawal,and the percentage may be even higher in pediatric living donor liver transplantation recipients.Several natural killer and γδT cell related markers have been identified to be associated with the tolerant state in liver transplantation patients.Despite the progress,clinical operational tolerance is still rare in liver transplantation.Reprogramming the recipient immune system by creating chimerism and regulatory cell therapies is among newer promising means to achieve clinical liver transplantation tolerance in the future.CONCLUSION:Although clinical operational tolerance is still rare in liver transplantation recipients,ongoing basic research and collaborative clinical trials may help to decipher the mystery of transplantation tolerance and extend the potential benefits of drug withdrawal to an increasing number of patients in a more predictable fashion.

HBsAg levels in HBeAg-positive chronic hepatitis B patients with different immune conditions

AIM: To investigate hepatitis B surface antigen (HBsAg) levels in patients with HBeAg-positive chronic hepatitis B (CHB) and different immune conditions.

Investigation on the Effects of Soluble Programmed Death-1 (sPD-1) Enhancing Anti-tumor Immune Response

Summary: By using semi-quantitative RT-PCR method, it was found that PD-L1 mRNA but not PD-L2 mRNA was expressed in H22 hepatoma cells and both PD-L1 and PD-L2 mRNAs were expressed in tumor tissues of tumor-bearing mice and upregulated as compared with muscle tissues in normal mice and H22 hepatoma cells. PD-L1 and PD-L2 were also expressed on the surface of the activated T cells. The soluble recombinant sPD-1 expressed from the constructed eukaryotic expression vector could enhance the lysis of tumor cells by lymphocytes stimulated specifically with antigen. The expresssion of sPD-1 by local gene therapy on the inoculation site of H22 hepatoma cells could inhibit the growth of tumor. The results of this study indicate that expression of soluble receptor of negative costimulatory molecules could reduce the inhibitory effect on T cells in tumor microenvironment and enhance the cytotoxicity of T cells on tumor cells. This possibly provides a new method of improving efficacy of tumor gene therapy.

Immunological tolerance of human hepatocyte xenograft induced by adenovirus vector-mediated CTLA4Ig gene transfer

BACKGROUND:Systemic administration of CTLA4Ig has been applied in inducing immunological tolerance of hepatocyte implants,but has potential for systemic immune inhibition.This study was designed to induce hepatocyte immunological tolerance by locally expressing CTLA4Ig in an attempt to improve the effectiveness of cell transplantation.METHODS:A normal human liver cell line(L02) was transfected with adenovirus vector containing the CTLA4Ig gene(Ad-CTLA4Ig-EGFP) in vitro,and the expression of CTLA4Ig by transfected cells was assessed by fluorescent imaging and immunocytochemical staining.Transfected cells then were injected into the spleen of Sprague-Dawley rats,the survival of cells was determined by immunohistochemistry,and the immune status was examined through CD4 + and CD69 + T cellcounts and ELISA detection of IL-2 in peripheral blood.RESULTS:L02 cells expressed CTLA4Ig in the cytoplasm for >4 weeks.Surviving L02 cells were observed in the experimental group at 3 and 4 weeks post-transplantation,while none was detected in the control group.Furthermore,the percentages of CD4 + and CD4 + CD69 + T cells in the CTLA4-transfected group were 24.5% and 45.1%,markedly lower than those in the control group at 4 weeks post-transplantation(P<0.01).Furthermore,the IL-2 level was also lower in the CTLA4transfected group than in the control group.CONCLUSION:Adenovirus-mediated CTLA4Ig gene transfer into human hepatocytes has the potential to become an effective method of inducing immunological tolerance in hepatocyte transplantation.