Antibodies to the hepatitis B e antigen (HBeAg) can be induced in HBeAg-transgenic mice by adoptive transfer of a specific T-helper 2 cell clone.

Production of antibody to hepatitis B e antigen (HBeAg); i.e., anti-HBe antibody,) in HBeAg-transgenic mice is believed to be mediated by T-helper 2 (Th2) cells. Injection of an HBeAg-specific Th2 clone into HBeAg-transgenic H-2k mice induced anti-HBe antibody production, confirming the function of Th2 cells in this model system.     

B and T cell tolerance and autoimmunity in autoantibody transgenic mice

One hallmark of systemic lupus erythematosus (SLE) is the presence of autoantibodies directed at a diverse group of proteins of the U1/Sm small nuclear ribonucleoprotein particles (snRNP). Patients with SLE and murine models of this disease generate high titers of affinity mature, isotype-switched autoantibodies characteristic of T cell-dependent immune responses. In this investigation, we made use of anti-snRNP Ig transgenic mice (2-12 Tg) to track regulation of autoreactive B cells in normal and autoimmune-prone mice. Autoantibody studies demonstrated that the regulation of anti-snRNP B cells is intact in non-autoimmune Tg mice, but not in MRL-lpr/lpr mice. We further utilize autoreactive Tg B cells as antigen-presenting cells (APC) and individual snRNP peptides to assess the presence of autoreactive T cells in the repertoire of non-autoimmune and MRL-lpr/lpr mice. We found that Tg B cells can direct specific T cell tolerance in a non-autoimmune-prone (C57Bl/6) background, whereas the same autoantibody transgene in MRL-lpr/lpr mice drives T cell autoimmunity. Moreover, Tg B cell APC could stimulate autoreactive T cells from wild-type (non-Tg) C57Bl/6 mice, indicating a lack of tolerance induction in the absence of the autoantigenic-presenting B cells. Thus, we have defined dual roles for autoantigen-presenting B lymphocytes in stimulating self-reactive T cells that inhabit the normal repertoire or, under some conditions, providing tolerance signals.     

Characterization of T-cell tolerance to hepatitis B virus (HBV) antigen in transgenic mice.

We made three different lines of hepatitis B virus (HBV) transgenic mice which express different amounts of hepatitis B e antigen (HBeAg) and/or hepatitis B core antigen (HBcAg) to analyse the cellular mechanisms of HBcAg specific T-cell tolerance. BS10 (official designation, 1.2HB-BS10) transgenic mice, which contain the whole HBV genome, express relatively high amounts of HBeAg in the serum and HBcAg in the liver. SPC mice, which contain hepatitis B virus core and precore gene, express small amounts of HBeAg in the serum but not HBcAg in the liver. SC33 mice, which contain only hepatitis B core gene, do not express HBeAg in the serum but express HBcAg in the liver. BS10 mice showed a very low anti-HBc antibody response after primary and secondary immunizations with recombinant HBcAg compared to transgenic host C57BL/6 (B6) mice. SPC mice showed an almost equal level of anti-HBc antibody response compared to B6 mice. SC33 mice contained anti-HBc antibody even before immunization and showed high titres of anti-HBc antibody response after immunization with HBcAg. Analysis of cellular site(s) of low responsiveness of BS10 mice revealed that proliferating and helper T cells are specifically tolerant to HBcAg. B cells and antigen-presenting cells in BS10 mice were not defective. SC33, SPC and BS10 mice differ a little in their developmental expression of HBc/HBeAg. Our results suggest critical roles of the nature (circulating versus non-circulating) as well as the time of expression of self-antigens in T-cell tolerance.     

H-2(d) mice born to and reared by HBeAg-transgenic mothers do not develop T cell tolerance toward the hepatitis B virus core gene products

The function of the secretory core gene product (HBeAg) of the human hepatitis B virus (HBV) is unknown. It has been proposed that this protein may be passed from the mother to her offspring at the perinatal stage where it might induce immune tolerance. In a previous study we have shown that the murine placenta presents an efficient barrier for the HBe protein and that H-2(b) mice born to HBeAg-positive transgenic mothers do not develop tolerance of specific cytotoxic T cells. In the present work we demonstrate that transgenic mice expressing high serum levels of HBeAg secrete only small amounts of this protein into their milk and excrete minute amounts of the viral gene product in their urine. Furthermore, it is shown that nontransgenic H-2(d) mice born to and reared by HBeAg-positive mothers exhibit a reactivity of HBc/eAg-specific CD4(+) Th cells and CD8(+) cytotoxic T cells comparable to that of normal isogenic control mice. In accordance with this observation the humoral immune responses directed against the HBeAg were comparable between these two groups of animals. This finding indicates that H-2(d) mice potentially exposed to small amounts of maternal HBeAg transferred by the transplacental, lactogenic, or renal route do not develop tolerance toward the HBV core gene products. These data challenge the hypothesis that a potential function of the HBeAg may be to operate as a tolerogen at the perinatal developmental stage.     

乙肝病毒蛋白对慢性乙型肝炎患者PBMCs功能的影响

目的：乙肝病毒蛋白对不同感染状态慢性乙型肝炎患者的外周血单核细胞（PBMCs）功能的影响。方法：收集乙肝表面抗原（HBeAg）阳性丙氨酸氨基转移酶（ALT）异常者40例（A组）， 乙肝e抗原（HBeAg）阳性ALT持续正常者20例（B组）， HBeAg及 乙肝病毒脱氧核糖核酸（HBV-DNA）阴性ALT正常者20例（C组），另外选择15例各型肝炎病原学标志检测均为阴性的健康体检者为正常对照组，分离培养外周血单核细胞，加入植物血凝素（PHA）、HBeAg、HBcAg, 培养48 h后，1 500 r/min 离心10 min,收集上清液-20 ℃保存，统一检测IFN-γ、IL-10含量。采用流式细胞仪检测外周血CD8＋CD28＋T细胞亚群。结果：IFN-γ在HBeAg阳性ALT正常组，HBeAg阳性ALT异常组中的含量明显低于正常对照组和HBeAg及 HBV-DNA阴性ALT正常组；IL-10在HBeAg阳性ALT正常组，HBeAg阳性ALT异常组中的含量明显高于正常对照组和HBeAg及 HBV-DNA阴性ALT正常组。CD8＋CD28＋T细胞在HBeAg阳性ALT正常组中明显低于其它各组。结论：HBeAg阳性的患者，Th1型细胞免疫反应明显低下，Th2型细胞免疫反应明显增高，CTL的数量减少。     

Identification of a unique double-negative regulatory T-cell population

Regulatory T (Treg) cells represent one of the main mechanisms of regulating self-reactive immune cells. Treg cells are thought to play a role in down-regulating immune responses to self or allogeneic antigens in the periphery. Although the function of Treg cells has been demonstrated in many experimental settings, the precise mechanisms and antigen specificity often remain unclear. In a hepatitis B e antigen-T-cell receptor (HBeAg-TCR) double transgenic mouse model, we observed a phenotypically unique (TCR+) CD4- /CD8- CD25(+/-) GITR(high) PD-1(high) FoxP3-) HBeAg-specific population that demonstrates immune regulatory function. This HBeAg-specific double-negative regulatory cell population proliferates vigorously in vitro, in contrast to any other known regulatory population, in an interleukin-2-independent manner.     

The disease progression in the keratin 14 IL-4-transgenic mouse model of atopic dermatitis parallels the up-regulation of B cell activation molecules, proliferation and surface and serum IgE

We have previously characterized the keratin 14 interleukin-4-transgenic (IL-4-Tg) mouse model of atopic dermatitis as a chronic pruritic inflammatory skin disease typified by skin infiltration of inflammatory cells and early up-regulation of Th2 cytokines and late surge of Th1 cytokines. In the present study, we examined the involvement of B cells. Systematic examinations of the following immunological parameters on B cells were carried out in non-Tg control mice and in IL-4-Tg mice at before disease onset and early and late disease stages so that we could determine the immunological sequence of events leading to the disease development: surface expressions of IA/IE, activation and costimulatory molecules, proliferation under LPS or IgM stimulation, quantification of cell surface and serum IgE, IgG1, and IgG2a. Our results showed that as the disease progresses from before onset to early disease and to late disease, there is a parallel increase in surface markers of B cell activation (IA/IE, CD44, CD69, CD80 and CD86), in B cell proliferation, and in cell surface and serum IgE. Significant increases of Th2-driven serum IgG1 and IgE in early disease was followed by significant increase of Th1-driven IgG2a in late disease. Importantly the significant increases of activation molecule (IA/IE), proliferation (to LPS), and surface IgE on B cells of the IL-4-Tg mice precedes the up-regulation of serum IgE and disease onset. These data suggest that activated B cells may play a role in atopic dermatitis disease development by up-regulating serum IgE concentration, which serves as a marker of disease onset.     

Breaking tolerance in hepatitis B surface antigen (HBsAg) transgenic mice by vaccination with cross-reactive, natural HBsAg variants

Processing exogenous hepatitis B surface antigen (HBsAg) of the hepatitis B virus (HBV) generates the K(b)-binding S(208-215) epitope 1; processing endogenous HBsAg generates the K(b)-binding S(190-197) epitope 2. Cross-reactive CD8(+) T cell responses were primed to epitope 1 but not epitope 2 when mice were immunized with natural HBsAg(ayw), or HBsAg(adw2) variants differing within both epitopes by one or two residues. Expression of HBsAg(ayw) from a transgene in the liver renders (HBs-tg) mice tolerant to epitope 1 of HBsAg(ayw). CD8(+) T cells specific for epitope 1 could be primed in HBs-tg mice by HBsAg(adw2); these specific CD8(+) T cells cross-reacted with epitope 1 processed from the transgene-encoded HBsAg(ayw). The liver of vaccinated HBsAg(ayw) transgenic mice showed severe histopathology and contained functional (IFNgamma-producing), cross-reactive CD8(+) T cells, and vaccinated HBs-tg mice showed reduced antigenemia. Hence, vaccination with natural HBsAg variants from different HBV sero/genotypes can prime cross-reactive, specific CD8(+) T cell immunity that breaks tolerance to HBsAg.     

慢性乙肝患者抗病毒治疗前后特异性T细胞免疫观察

目的 了解抗病毒治疗前后慢性乙型肝炎患者特异性T淋巴细胞对HBV抗原蛋白免疫应答的变化及其特征.方法 收集17例慢性乙型肝炎患者抗病毒治疗前及治疗后1个月、3个月的外周血单个核细胞,以HBV特异性抗原蛋白HBsAg、HBcAg和HBeAg为刺激物,酶联免疫斑点法检测其分泌IFN-γ产生斑点的情况.同时对血清HBV DNA和HBsAg、HBeAg等病毒学指标及谷丙转氨酶(ALT)等生化学指标进行榆测并分析其相关性.结果 治疗前,所有患者ALT、总胆红素(TBiL)均高于正常上限,17例患者HBV DNA均大于104拷贝/ml;治疗1个月后,ALT复常率为35.3%,9例患者HBV DNA降为检测下限以下;治疗3个月后,ALT复常率为58.8%,有11例患者HBV DNA降为检测下限以下.抗病毒治疗前、治疗1个月、治疗3个月患者针对HBV特异性蛋白总的T细胞反应阳性率分别为64.7%、76.5%和82.4%,其差别无统计学意义.不论治疗前后,患者对HBeAg的特异性T细胞反应频率和平均反应强度最高;治疗后,对3种蛋白的特异性T细胞反应频率和平均反应强度各有不同程度的增加,其中以对HBcAg蛋白的平均反应强度的增强最明显,治疗前和治疗3个月,治疗1个月和治疗3个月之间的差别都有统计学意义.患者对HBcAg蛋白的特异性T细胞反应平均反应强度与病毒载量有明娃负相关,与血清ALT无明显相关性.结论 本研究结果提示抗病毒治疗后,患者对HBV的特异性T细胞免疫应答有所增强,这种改变可能与HBV DNA的下降有关,检测HBV特异性T细胞反应对丁解患者的免疫状态有重要的意义.

Abstract：

Objective To explore the responses of antigen-specific T cells stimulated by hepatitis B virus(HBV)-specific proteins in chronic hepatitis B patients accepting antiviral therapy. Methods Seventeen patients with chronic hepatitis B (CHB) accepting antiviral therapy were included in this study. The peripheral blood monocular cell ( PBMC) were separated from the whole blood collected at the three different time of before and one and three months after accepting antiviral therapy. ELISPOT assay was used to detect the frequency and strength of secreting IFN-γ cells of PBMC stimulated by HBsAg, HBcAg and HBeAg. HBV virus loading, HBsAg, HBeAg, ALT and AST in serum were detected at the same time. Results After three months therapy, ALT, TBiL were improved in all patients, and HBV DNA level were dropped and undetectable in 11 cases. The rates of T cell response in patients to HBV specific proteins were 64. 7% , 76. 5% and 82. 4% at the time of before and one and three months after accepting antiviral therapy, respectively. The frequency of responses of antigen-specific T cells stimulated by HBcAg was higher than that stimulated by HBsAg or HBeAg, and the frequency was enhanced after antiviral therapy. The average response magnitude was expressed as spot forming cells (SFC) per million input cells. SFC of T cell responses to HBcAg was also higher than to HBsAg or HBeAg. There was no significant difference in SFC of T cell responses to HBsAg or HBeAg at the time of before and after antiviral therapy, but there were significant difference in SFC of T cell responses to HBcAg at the time of before and after antiviral therapy. SFC of T cell responses to HBcAg was negatively associated with HBV DNA, and no associated with level of ALT in serum. Conclusion The responses of antigen-specific T cells were improved in CHB patients accepting antiviral therapy which associated with the decrease of HBV DNA. It suggested to investigate HBV specific T cell responses was important.     

不同类型乙肝病毒感染者HBV抗原特异性T细胞免疫应答

目的 了解不同类型HBV感染人群T细胞对HBV抗原蛋白免疫应答的差别及特征.方法 76例研究对象分为四组,乙肝携带者组和既往乙肝感染患者组、急乙组、慢乙组,酶联免疫斑点法检测其外周血T细胞对HBV特异性抗原蛋白HBsAg、HBcAg和HBeAg免疫应答.结果 (1)携带者组对HBeAg的反应频率较高,而既往感染者对HBcAg和HBeAg的反应频率较高.急乙组和慢乙组对三种蛋白的反应频率无差别.(2)急乙组和慢乙组对HBsAg的反应频率明显高于既往感染组.急乙组、慢乙组和既往感染组对HBcAg的反应频率明显高于携带者组.对HBeAg的反应频率各组间无差别.(3)慢乙组对HBcAg的反应强度明显高于HBsAg.既往感染组患者对三种蛋白的反应强度依次为HBcAg＞ HBeAg＞ HBsAg.急乙组和携带者组对三种蛋白的反应强度无差别.(4)对HBsAg的反应强度从高到低依次为急乙组＞慢乙组＞携带者组和既往感染组.对HBcAg的反应强度是急乙组和慢乙组和既往感染组明显强于携带者组.对HBeAg的反应强度,急乙组高于慢乙组,其余各组间无差别.结论 急乙、慢乙和既往感染者对HBcAg的T细胞免疫反应为主,而携带者以HBeAg的T细胞免疫反应为主.     

Emergence of a type II collagen-specific helper T cell response

Antigen-driven development of persistent self-reactive Th cells underlies the chronic, progressive nature of many autoimmune diseases. It is crucial to understand the behavior of these self-reactive Th cells; however, they have been notoriously difficult to isolate directly ex vivo. Collagen-induced arthritis (CIA) can be initiated in I-A(q)-expressing mice (DBA/1) using heterologous type II collagen (cII) immunization and is dependent on Th cells that are specific for a single immunodominant epitope. Here, we identify one compartment of cII-specific Th cell using TCR beta expression, cell surface phenotype, and direct single-cell repertoire analysis. A subpopulation of CD4(+)V beta 10(+) T cells up-regulates both CD44 and GL7 and expands significantly in response to initial priming in the majority of animals (D9: 70%). The cII-specific V beta 10(+) primary responders are further resolved through expression of a highly restricted junctional region, previously associated with autoimmune disease. This cII-specific clonotype rapidly re-expands upon antigen recall and can be isolated from the lymph nodes of arthritic animals. These single-cell analyses quantify the emergence, decline and rapid re-emergence of a self-reactive Th cell population in vivo and outline one strategy for isolating these cells directly ex vivo.     

Characteristics of the early phase of chronicity in acute hepatitis B infection

The mechanism of development of chronicity after acute hepatitis B infection has not been elucidated fully. Following a single source outbreak of hepatitis B among 79 adult women, three patients (4%) became chronic carriers of hepatitis B virus (HBV). We compared features of the virus and antibody response of the latter three patients with those of 12 HBeAg-positive cases with resolving infection. The virus genotype was D, antigenic subtype ayw2. Base sequence analysis of S- and C-gene regions revealed no differences between the two groups. During the acute illness the three patients who developed chronicity had a remarkable transient reduction of HBsAg, HBeAg, and HBV DNA levels at 14-20 weeks after infection, the time of HBeAg seroconversion in the patients who cleared the infection. One HBeAg-specific monoclonal antibody (HBOT.95A) used as solid-phase antibody in a sandwich enzyme immunoassay detected an increased HBeAg signal in 2 of the 3 patients that developed chronicity and in 1 of the 12 patients who recovered. The latter patient had an exceptional long period of HBsAg antigenemia. Standard HBeAg assays detected HBeAg in all cases. HBeAg and anti-HBe-positive serum samples from the patients who recovered could inhibit the HBOT.95A response. The results suggest that chronic hepatitis B develops after an interruption of immune clearance. Differentiation of the antibody response to HBeAg may help to find patients with an increased risk for this interrupted immune clearance who might be candidates for an early intervention therapy.     

Deletional tolerance prevents AQP4‐directed autoimmunity in mice

Neuromyelitis optica (NMO) is an autoimmune disorder of the central nervous system (CNS) mediated by antibodies to the water channel protein AQP4 expressed in astrocytes. The contribution of AQP4‐specific T cells to the class switch recombination of pathogenic AQP4‐specific antibodies and the inflammation of the blood–brain barrier is incompletely understood, as immunogenic naturally processed T‐cell epitopes of AQP4 are unknown. By immunizing Aqp4 ^?/? mice with full‐length murine AQP4 protein followed by recall with overlapping peptides, we here identify AQP4(201‐220) as the major immunogenic IA^b‐restricted epitope of AQP4. We show that WT mice do not harbor AQP4(201–220)‐specific T‐cell clones in their natural repertoire due to deletional tolerance. However, immunization with AQP4(201–220) of Rag1 ^?/? mice reconstituted with the mature T‐cell repertoire of Aqp4 ^?/? mice elicits an encephalomyelitic syndrome. Similarly to the T‐cell repertoire, the B‐cell repertoire of WT mice is “purged” of AQP4‐specific B cells, and robust serum responses to AQP4 are only mounted in Aqp4 ^?/? mice. While AQP4(201–220)‐specific T cells alone induce encephalomyelitis, NMO‐specific lesional patterns in the CNS and the retina only occur in the additional presence of anti‐AQP4 antibodies. Thus, failure of deletional T‐cell and B‐cell tolerance against AQP4 is a prerequisite for clinically manifest NMO.     

Hepatitis B e antigen‐negative mutations in the precore and core promoter regions in Korean patients

Most patients with hepatitis B e antigen (HBeAg)‐negative chronic hepatitis B have variants of the hepatitis B virus (HBV) that include mutations in the precore or core promoter regions of the HBV genome. The aim of this study was to investigate the patterns of precore and core promoter mutations and their relationship to HBeAg expression in Korean patients. Four hundred seventy‐five Korean patients with chronic HBV infection between February 1995 and December 2003 were enrolled in this study. There were 236 HBeAg‐positive and 239 HBeAg‐negative patients. Blood samples were tested for HBsAg, anti‐HBs, HBeAg, hepatitis B e antibody (anti‐HBe), liver function tests, and serum HBV DNA. Mutations in the precore and core promoter regions were determined by direct sequencing. In the core promoter region, the C1740, C1753, T1762/A1764, and T1766 mutations were associated with HBeAg escape (all; P < 0.05). In the precore region, a higher frequency of the C1802, A1828, T1846, A1850, C1858, T1862, and A1896 mutations was found in HBeAg‐negative patients (all; P < 0.05). In particular, the A1896 mutation was associated with high serum levels of ALT and HBV DNA in HBeAg‐negative patients (P = 0.014 and 0.026, respectively). Mutations around the Kozak sequence (nucleotides 1809–1812) were found in 6.7% of patients and were not associated with undetectable HBeAg (P = 0.13). In Korean patients, various mutations in the precore and core promoter regions were associated with HBeAg escape and amelioration of hepatic inflammation in HBeAg‐ negative patients. Only the A1896 mutation contributed to HBeAg‐negative chronic hepatitis B. J. Med. Virol. 81:594–601, 2009 © 2009 Wiley‐Liss, Inc.     

Dose-dependent T cell tolerance to an immunodominant self peptide

We have previously described a model of tolerance to self peptides in a mouse transgenic (Tg) line producing secreted hen egg-white lysozyme (HEL). The HEL cDNA was placed under the control of a ubiquitous promoter expressed early in embryogenesis, so that HEL should be present in Tg mice throughout the development of the immune system. Since individual HEL Tg mice express different amounts of serum HEL, we were previously able to show that H-2^d mice with HEL blood level > 10 ng/ml are tolerant to HEL and to the immunodominant (ID) peptide 108–116. However, autoreactive T lymphocytes recognizing the HEL subdominant (SD) peptides 74–96 and 1–18 still persist and the SD-specific responses disappear at higher blood HEL concentrations. In the present work, we have studied HEL Tg H-2^d mice with HEL serum levels < 10 ng/ml (HEL-low Tg animals). We find that 50% of Tg animals with HEL blood concentration < 2 ng/ml are responsive to HEL in T cell proliferation assays, although these responses are lower than those seen in non-Tg control mice. The HEL-specific T lymphocytes react only with 15-mer overlapping peptides encompassing the single H-2^d ID region of HEL (residues 102–122); whereas the 9-mer minimal ID peptide 108–116, which strongly triggers non-Tg T cells, is unable to stimulate auto-reactive T cells in vitro from HEL-low Tg mice. Altogether, our results suggest that T lymphocytes specific for the minimal ID peptide are deleted or inactivated, while T cell clones of lower affinity and reacting with epitopes on longer peptides persist. Thus, the high affinity ID peptide-specific T cell clones can be negatively selected even in the presence of low amounts of HEL.     

In vivo administration of interleukin-2 turns on anergic self-reactive T cells and leads to autoimmune disease.

One major mechanism of self tolerance involves the deletion of T cell clones in the thymus. In athymic mice, tolerance to self antigens must be generated extrathymically. T cells with self-reactive receptors undergo either peripheral clonal deletion or become unresponsive (i.e. anergic). The unresponsive state of human and mouse T cell clones in vitro can be reversed by the addition of exogenous interleukin (IL)-2, thus transforming anergic T cells to an activated state. Here it is shown that the in vivo delivery of IL-2 to athymic BALB/c nu/nu mice abrogates the anergic state of self-reactive V beta 3+ and V beta 11+ T cells [which are normally deleted in the minor lymphocyte stimulatory (Mls)-1b-, I-E(+)-expressing euthymic counterparts]. Thus, V beta 3+ and V beta 11+ T cells from IL-2-treated nude mice proliferate in response to T cell receptor cross-linking and acquire effector functions as measured by their ability to deliver aid to B cells upon specific stimulation. This activation correlates with the development of autoimmune manifestations (DNA autoantibodies, rheumatoid factors, erythroleukopenia and minimal change nephritis) in these IL-2-treated mice.     

Secretion of polyalbumin receptors in vitro

The nature of hepatitis B surface antigen (HBsAg)-associated receptors for polymerized human serum albumin (pHSA-R) and their relationship to hepatitis B e antigen (HBeAg) and human serum proteins have not been defined. We studied by radioimmunoassay and by electron microscopy HBsAg-associated pHSA-R secreted in vitro by a human hepatocellular carcinoma cell line (PLC/PRF/5) and by mouse 3T3 fibroblasts after transfection with cloned hepatitis B virus (HBV) DNA (4.10 cells). PLC/PRF/5 cells expressed only HBsAg, whereas 4.10 cells secreted also HBeAg. There was no significant difference in the production of HBsAg, HBeAg, and pHSA-R when the cells were cultured in the presence or absence of fetal calf serum. Secretion of pHSA-R by the two cell lines for a given amount of HBsAg was equal irrespective of the presence or absence of HBeAg. Supernatants from both cell lines grown in serum-free medium did not contain any Clq or albumin when tested by immunodiffusion. The ability of a transfected mouse cell line to produce HBsAg with pHSA-R activity strongly suggests that pHSA-R is coded by the HBV genome and does not depend on the presence of human serum proteins. In addition, our findings fail to demonstrate any correlation between HBeAg production and pHSA-R.     

Immune Regulation by T Regulatory Cells in Hepatitis B Virus‐Related Inflammation and Cancer

Hepatocellular carcinoma (HCC) is the leading cause of cancer death, and hepatitis B virus (HBV) infection is one of the commonest causes in Asian countries. India has the second largest pool after China for hepatitis B‐infected subjects. HBV clearance is T cell dependent, and one of the reasons for T cells hyporesponsiveness is due to mass production of regulatory T cells (Tregs) through activation of Notch signalling, which suppress CD4/CD8 T cells. Tregs are important to maintain cellular homoeostasis; however, during viral infection increase of Tregs is inversely proportional to HBV DNA titres. Tregs exert their suppressive effect either via cell‐to‐cell contact or through release of interleukin (IL)‐2, IL‐10, TGF‐β and IL‐35. In Chronic hepatitis B virus CHBV infection, PD‐1 pathway also gets activated and is involved in promoting tolerance. However, with Tregs induction, virus‐specific T cell responses also get decreased. Circulatory and intratumoural Tregs promote development of HBV‐specific HCC more by decreasing and impairing the effector functions of CD8 T cells. Antiviral therapies and PD‐1 blockade strategy had shown the inhibition of Tregs and reduction in HBV DNA. However, inhibition of HBV‐specific Tregs is major challenge for future therapies. New cytokine blockade therapies have emerged as potential therapeutic potentials.     

Excess BAFF rescues self-reactive B cells from peripheral deletion and allows them to enter forbidden follicular and marginal zone niches

The role of BAFF in B cell self tolerance was examined by tracking the fate of anti-HEL self-reactive B cells in BAFF transgenic mice using four different models of self-reactive B cell deletion. BAFF overexpression did not affect the development of self-reactive B cells normally deleted in the bone marrow or during the early stages of peripheral development. By contrast, self-reactive B cells normally deleted around the late T2 stage of peripheral development were rescued from deletion, matured, and colonized the splenic follicle. Furthermore, self-reactive B cells normally selectively deleted from the marginal zone repopulated this compartment when excess BAFF was present. Self-reactive B cells rescued by excess BAFF were not anergic. BAFF overexpression therefore rescued only self-reactive B cells normally deleted with relatively low stringency and facilitated their migration into otherwise forbidden microenvironments. This partial subversion of B cell self tolerance is likely to underlie the autoimmunity associated with BAFF overexpression.