Liver injury is associated with enhanced regulatory T-cell activity in patients with chronic hepatitis B

Interaction of peripheral CD4+CD25+CD127− Tregs with prolactin in HCV hepatocellular carcinoma: oncogenic or immunogenic mechanisms

Background and objective

There is little and conflicting data about the peripheral CD4+CD25+CD127− Tregs in patients with hepatocellular carcinoma (HCC) of various etiologies. The expressed membrane-bound transforming growth factor (mTGF-β1) on these Tregs is a marker of their suppressive function. Prolactin suppresses Tregs function in healthy subjects but enhances local Tregs in breast cancer. Our study is the first to assess the frequency and function of CD4+CD25+CD127−Tregs and their association with clinicopathological features and staging in HCV-related HCC and to determine whether prolactin acts as an oncogenic growth factor or participates in the regulation of the immune response mediated by peripheral Tregs. In patients with HCV- elated HCC, HCV-cirrhotic patients, and healthy subjects, we measured the frequency of peripheral traditional CD4+ CD25+ Tregs and well-characterized CD4+CD25+CD127−Tregs and their mTGF-β1 using flow cytometric analysis and measured serum prolactin level.

Results

The frequency of CD4+ CD25+ and CD4+CD25+CD127− Tregs was comparable between HCC and cirrhotic patients and healthy subjects. Serum prolactin and mTGF-β1 on traditional and CD4+CD25+CD127− Tregs were significantly higher in HCC and cirrhotic patients than healthy subjects with an insignificant difference between HCC and cirrhotic patients. Roc curve analysis revealed that cutoff value for mTGF-β1 on Tregs ≥ 13.5% is a good specific (87%) but low sensitive (54%) test in discriminating HCC patients from healthy subjects. The frequency of Tregs and mTGF-β1 were not correlated to clinicopathological characteristics or staging of HCC. Prolactin was higher in the multifocal lesions and negatively correlated to expressed mTGFβ1. The expressed mTGF-β1 was positively correlated with hemoglobin and alanine transaminase. The traditional Tregs was positively correlated with hemoglobin and albumin.

Conclusion

mTGFβ1, as a marker for suppressive function of peripheral CD4 + CD25 + CD127-Tregs, has a diagnostic role in discriminating HCV-related HCC patient from healthy subjects, unfortunately not from HCV-related cirrhotic patients. Serum prolactin has an oncogenic role as it is correlated to multiple focal lesions. It also impedes the suppressive function of peripheral Tregs as an immunogenic role. mTGF-β1 is related to hemoglobin and hepatic inflammation.

Trauma induces expansion and activation of a memory-like Treg population

CD4+ regulatory T cells (Tregs) are acutely activated by traumatic injury, which suggests that they may react to injury with similar kinetics as memory T cells. Here, we used a mouse burn trauma model to screen for memory-like T cell responses to injury by transferring T cells from sham or burn CD45.1 mice into CD45.2 mice and performing secondary injuries in recipient mice. Among all T cell subsets that were measured, only Tregs expanded in response to secondary injury. The expanded Tregs were a CD44high /CD62Llow subpopulation, markers indicative of memory T cells. CyTOF (cytometry by time-of-flight) mass cytometry was used to demonstrate that injury-expanded Tregs expressed higher levels of CD44, CTLA-4, ICOS, GITR, and Helios than Tregs from noninjured mice. Next, we tested whether a similar population of Tregs might react acutely to burn trauma. We observed that Tregs with a phenotype that matched the injury-expanded Tregs were activated by 6 h after injury. To test if Treg activation by trauma requires functional MHC class II, we measured trauma-induced Treg activation in MHC class II gene deficient (MHCII-/- ) mice or in mice that were given Fab fragment of anti-MHC class II antibody to block TCR activation. Injury-induced Treg activation occurred in normal mice but only partial activation was detected in MHCII-/- mice or in mice that were given Fab anti-MHCII antibody. These findings demonstrate that trauma activates a memory-like Treg subpopulation and that Treg activation by injury is partially dependent on TCR signaling by an MHC class II dependent mechanism.

Hepatitis B envelope antigen increases Tregs by converting CD4+CD25- T cells into CD4+CD25+Foxp3+ Tregs

Hepatitis B virus (HBV) can establish a lifelong chronic infection in humans, leading to liver cirrhosis, liver failure and hepatocellular carcinoma. Patients with chronic hepatitis B (CHB) exhibit a weak virus-specific immune response. Regulatory T cells (Tregs) play a key role in regulating the immune response in patients with CHB. Patients with hepatitis B envelope antigen (HBeAg)-positive CHB harbored a higher percentage of Tregs in their peripheral blood than those with HBeAg-negative CHB. However, whether and how HBeAg manipulates the host immune system to increase the population of Tregs remains to be elucidated. The present manuscript describes a preliminary immunological study of HBeAg in a mouse model. Multiple potential CD4⁺ T cell epitopes in HBeAg were identified using Immune Epitope Database consensus binding prediction. It was demonstrated that HBeAg treatment increased the numbers of Tregs in mouse spleens in vitro and in vivo. Furthermore, it was indicated that the HBeAg-mediated increase in Tregs occurred through the conversion of CD4⁺CD25^- T cells into CD4⁺CD25⁺Foxp3⁺ Tregs. Additionally, in vitro study illustrated that HBeAg stimulated murine spleen cells to produce increased transforming growth factor-β, which is required to enable HBeAg to convert T cells into Tregs. The results of the present study may provide further evidence of the effect of HBeAg on Tregs and aid in the development of novel HBeAg-based immunotherapy for CHB.

Increased Th17 functions are accompanied by Tregs activities in lupoid leishmaniasis

The immunopathogenesis of lupoid leishmaniasis is challenging. Although an appropriate immune response is critical for controlling these parasites, inappropriate inflammatory reactions can also promote increased pathology. The role of immune modulatory effect of the main transcription factors and cytokines of T regulatory and Th17 cells in pathogenesis of leishmaniasis chronicity was investigated in this study. The gene expression of interleukin-10 (IL-10), transforming growth factor-β (TGF-β1), forkhead box P3 (Foxp3), interleukin-17(IL-17A) and retinoic acid-related orphan receptor gamma t (ROrC) was assessed in peripheral blood mononuclear cells of eighty blood samples from cutaneous leishmaniasis (CL) patients with usual lesions (n = 31), lupoid lesions (n = 29) and healthy volunteers (n = 20). Quantitative relative real-time PCR (qRT-PCR) was performed using the Taqman and Sybergreen methods for expression of target genes. Expression of Foxp3 (P = .013), IL-10 (P < .001) and IL-17A (P < .001) was significantly higher in lupoid patient compare to the nonlupoid group. Expression of Foxp3 (P < .001), IL-10 (P < .001) and IL-17A (P = .033) was significantly more in nonlupoid subjects than in healthy volunteers, except for RORγt. These findings suggest that Foxp3+ cells, IL-10 and IL-17 play important roles in the immunopathogenesis of CL and that these roles differ depending on the causal leishmania species and different body compartments.

Memory Regulatory T cells Increase Only In Inflammatory Phase of Chronic Hepatitis B Infection and Related to Galectin-9/Tim-3 interaction

CD4⁺Foxp3⁺ regulatory T cells (Tregs) are the main immune suppressors with subpopulation of inflamed-tissue related memory Tregs (mTregs) and non-related resting Treg (rTregs). Previously, Treg was proposed to be the cause of chronicity of hepatitis B virus (HBV) infection but with controversies. We then investigated the role of mTregs in distinct immune phases of chronic HBV infection, especially the non-inflammatory versus inflammatory phases. It was found mTregs but not rTregs increased only in the inflammatory phase and correlated with serum alanine aminotransferase (ALT) level. These mTregs accumulated in the inflamed liver, expressed significantly higher Tim-3, CCR4, CCR5 and fewer CCR7, and possessed potent suppressive function. These mTregs mainly originated from natural Tregs because of high Helios expression. Hierarchical clustering analysis showed higher frequency of mTreg was concordant with higher serum ALT and galectin-9 levels. Furthermore, galectin-9 could expand mTregs through galectin-9/Tim-3 interaction. In conclusion, increased mTregs are found only in inflammatory phase of chronic HBV infection. Galectin-9, associated with liver inflammation, contributes to the expansion of mTregs through galectin-9/Tim-3 interaction. Therefore, this expansion of mTregs only reflects as an immune regulatory mechanism to limit the on-going liver damages rather than the cause of chronicity of HBV infection.

Role of T-regulatory cells in the response to hepatitis B vaccine in hemodialysis patients

Human disease elicits a complex array of biological processes that results in long-term protective immunological memory to infectious agents. Chronic kidney disease is known to impair induction of sustained immunological memory to hepatitis B vaccine (HBVax) antigens. We asked the question: Does end-stage renal disease promote changes in subtypes of regulatory T (Treg) cells that correlate with diminished amnestic response to HBVax antigen compared to healthy controls? The study design and setting was a prospective observational cohort at a veterans affairs medical center. End-stage renal disease patients on hemodialysis (HD) were compared with individuals with self-reported normal kidney function. All subjects received HBVax. Peripheral blood was sampled for assessment for Treg cells pre and post vaccination. CD4+ FOXP3 Treg numbers were similar between HD and healthy subjects during a 14-day time period post vaccination. HD subjcts had lower anti-HBSag antibody than CON (control) subjects (330 ± 108.7 vs. 663.1 ± 129.7 IU/mL; P = 0.063). Hemodialysis subjects with resting Tregs higher than the median value in our cohort demonstrated a significantly lower change in HBsAB at 30 days post booster vaccination (P = 0.030). No such relationship was found for the activated Treg subset among HD subjects, or either subset among CON subsets. In our limited comparison study of 11 HD and 8 CON subjects, Treg subsets did not differ between the two groups; but differences in the suppressive Treg numbers in the HD group could explain the altered antibody response to HBVax and is worthy of further study.

Increased regulatory T cells in patients with liver cirrhosis correlated with hyperbilirubinemia and predict bacterial complications

BACKGROUND AND AIM

Patients with liver cirrhosis (LC) were regarded as immunocompromised status with high incidence of bacterial infection. Regulatory T cell (Treg cell) is known as an immune suppressor and also plays an important role in patients with sepsis. This paper aims to study the role of Treg cells in patients with liver cirrhosis and their correlations to bacterial complications.

METHODS

Thirty-three normal controls (NC) and 82 cirrhotic patients were enrolled for the case-control study. The Treg cells, defined as CD4+ CD25+ Foxp3+ T cells, in peripheral blood of these patients were evaluated.

RESULTS

The percentage of Treg cells increased significantly in patients with liver cirrhosis when compared with normal volunteers. Furthermore, this increase of Treg cells was mainly memory phenotype defined as CD45RO+ Treg cells and was significantly correlated with serum bilirubin levels as evaluated by multiple linear regression analysis. In addition, the tumor necrosis factor (TNF)-α receptor II (TNFRII) expression also significantly increased on Treg cells in these patients. Interestingly, these membranous TNFRII would be shed and released into supernatant. Lastly, this increased percentage of Treg cells in cirrhotic patients correlate well with and predict subsequent bacterial complications.

CONCLUSION

The Treg cells, mainly with memory phenotype and with high TNFRII expression, increased significantly in patients with liver cirrhosis and significantly correlated with the serum bilirubin levels. Furthermore, this increased Treg cells correlate with and predict subsequent bacterial complications in cirrhotic patients.

Advances in understanding relationship between peripheral blood CD4+CD25+ regulatory T cells and antiviral treatment in CHB patients

The immunosuppressive function of CD4⁺ CD25⁺ regulatory T cells may closely associate with the occurrence, development and prognosis of CHB patients. The change and function of CD4⁺CD25⁺ regulatory T cells in CHB patients undergoing antiviral treatment have aroused the attention of scholars. Here we review the types, immunophenotypes, and function of CD4⁺CD25⁺ regulatory T cells, as well as the relationship between peripheral blood CD4⁺CD25⁺ regulatory T cells and antiviral treatment in CHB patients.

Intrahepatic interleukin-17+ T cells and FoxP3+ regulatory T cells cooperate to promote development and affect the prognosis of hepatocellular carcinoma

BACKGROUND AND AIM

Recent studies have shown that imbalance between tumor-infiltrating interleukin (IL)-17(+) T cells and regulatory T cells (Tregs) is an important regulator of progression in various cancers, but little is known regarding this imbalance in hepatocellular carcinoma (HCC). This study explored the role of imbalance between IL-17(+) T cells and Tregs in the immunopathogenesis of HCC in patients with chronic hepatitis B (CHB) infection.

METHODS

Fifty-six of patient-matched tumors and peritumoral surgical specimens from 56 patient with HCC and 136 liver biopsies specimens from 46 patients with CHB, 37 with atypical hyperplasia (AH), and 53 with HCC were enrolled. The expressions of IL-17, FoxP3, CD4, and CD8 in liver tissue were measured by immunochemistry for the evaluation of liver-infiltrating lymphocytes.

RESULTS

The density of liver infiltrated FoxP3(+) Tregs was increased in a stepwise manner from CHB to AH then HCC, while there was a decreasing trend for the density of IL-17(+) T cells and CD8(+) T cells. In surgical specimens of less differentiated HCC, the quantity of tumor-infiltrating FoxP3(+) Tregs was significantly lower and IL-17(+) T cells and CD8(+) T cells were significantly higher. Additionally, peritumoral IL-17(+) T cells were increased in poorly differentiated HCC. High intratumoral FoxP3(+) Tregs with high intratumoral IL-17(+) T cells showed a significantly lower overall survival (OS) and disease-free survival (DFS) compared with other groups (OS, P = 0.033; DFS, P = 0.004). High intratumoral FoxP3(+) Tregs with high peritumoral IL-17(+) T cells showed a significantly lower survival rate compared with other groups (OS, P < 0.001 and DFS, P < 0.001).

CONCLUSION

Our findings suggest that intrahepatic IL-17(+) T cells and FoxP3(+) Tregs may cooperate to promote the progression of HCC.

Regulatory T cells are the most important determinant factor of hepatitis B infection prognosis: a systematic review and meta-analysis

INTRODUCTION

Association of increased levels of CD4(+)CD25(+) regulatory T cells (Tregs) with impaired immune response and hepatitis B infection progression has been proposed. For determination of Tregs various effects among hepatitis B infected patients we performed a meta-analysis of the available literature.

METHODS

Current content, abstract books of congresses, and electronic databases were searched. Critical appraisal has been done. According to the result of heterogeneity tests (Q, I-squared, and Tau-squared), we used fix/random model for analysis.

RESULT

Twelve studies that fulfilled inclusion criteria entered to analysis. Pooled estimation of reported results showed that CD4(+)CD25(+) Tregs have higher expression of forkhead box P3 (FoxP3) versus CD4(+)CD25(-) Tregs, odd ratio (OR) was 31.49 (95% Confidence Intervals (CI): 5.09-194.94). Tregs level among chronic hepatitis B (CHB) patients was 77% (OR=1.77 95% CI: 1.43-2.19) higher than healthy controls. Patients with more than 10,000,000 HBV copies/ml have higher level of Tregs (OR: 1.24 95% CI: 1.08-1.41) comparing subjects with less than that. CHB patients have increased level of Tregs versus acute hepatitis B patients (OR=1.33 95% CI: 1.16-1.52). CD8 cells activity increased significantly after depletion of circulating Tregs (OR=1.93 CI: 1.37-2.73). Also, Tregs reduce response to treatment and non-responders to INF-α had higher level of Tregs (OR=1.60 95% CI: 1.09-2.36). In addition, Tregs increase risk of hepatocellular carcinoma (HCC) (OR=1.36 95%CI: 1.10-1.69).

CONCLUSION

Tregs influence HBV infected patients in various states. Tregs determine the disease prognosis by leading to infection progression and impairing immune response. So, Tregs are therapeutic target for immunotherapy of HBV infection.

Regulatory T cells in the pathogenesis and healing of chronic human dermal leishmaniasis caused by Leishmania (Viannia) species

BACKGROUND

The inflammatory response is prominent in the pathogenesis of dermal leishmaniasis. We hypothesized that regulatory T cells (Tregs) may be diminished in chronic dermal leishmaniasis (CDL) and contribute to healing during treatment.

METHODOLOGY/PRINCIPAL FINDINGS

The frequency and functional capacity of Tregs were evaluated at diagnosis and following treatment of CDL patients having lesions of ≥6 months duration and asymptomatically infected residents of endemic foci. The frequency of CD4(+)CD25(hi) cells expressing Foxp3 or GITR or lacking expression of CD127 in peripheral blood was determined by flow cytometry. The capacity of CD4(+)CD25(+) cells to inhibit Leishmania-specific responses was determined by co-culture with effector CD4(+)CD25(-) cells. The expression of FOXP3, IFNG, IL10 and IDO was determined in lesion and leishmanin skin test site biopsies by qRT-PCR. Although CDL patients presented higher frequency of CD4(+)CD25(hi)Foxp3(+) cells in peripheral blood and higher expression of FOXP3 at leishmanin skin test sites, their CD4(+)CD25(+) cells were significantly less capable of suppressing antigen specific-IFN-γ secretion by effector cells compared with asymptomatically infected individuals. At the end of treatment, both the frequency of CD4(+)CD25(hi)CD127(-) cells and their capacity to inhibit proliferation and IFN-γ secretion increased and coincided with healing of cutaneous lesions. IDO was downregulated during healing of lesions and its expression was positively correlated with IFNG but not FOXP3.

CONCLUSIONS/SIGNIFICANCE

The disparity between CD25(hi)Foxp3(+) CD4 T cell frequency in peripheral blood, Foxp3 expression at the site of cutaneous responses to leishmanin, and suppressive capacity provides evidence of impaired Treg function in the pathogenesis of CDL. Moreover, the concurrence of increased Leishmania-specific suppressive capacity with induction of a CD25(hi)CD127(-) subset of CD4 T cells during healing supports the participation of Tregs in the resolution of chronic dermal lesions. Treg subsets may therefore be relevant in designing immunotherapeutic strategies for recalcitrant dermal leishmaniasis caused by Leishmania (Viannia) species.

Foxp3+ regulatory T cells are associated with the natural history of chronic hepatitis B and poor prognosis of hepatocellular carcinoma

BACKGROUND

Recent studies have focused on regulatory T cells (Tregs) in chronic hepatitis B (CHB) and hepatocellular carcinoma (HCC) and they were also conducted independently of each other.

AIMS

This study tried to characterize Tregs in blood and tumour infiltration, and to explore the correlations between Tregs and the context of chronic hepatitis B in HCC patients.

METHODS

The liver-resident Tregs and CD8(+) T cells on core biopsy were investigated using immunohistochemistry staining in individuals (n = 209) with CHB (n = 47), HCC (n = 137) or healthy controls (n = 25). Circulating Tregs were detected in the above patients with CHB (n = 27) or HCC (n = 101) by flow cytometry.

RESULTS

The number of tumour-infiltrating and circulating FoxP3(+) Tregs was significantly high in patients with CHB (P < 0.001). However, there were fewer intratumoural Tregs in patients with advanced HCC than those in patients with early stage HCC (P = 0.043); In contrast, the circulating Tregs frequency increased during the progression of HCC (P = 0.024). Increased tumour-infiltrating and circulating FoxP3(+) Tregs were associated with poor overall survival (P = 0.041, 0.002 respectively) and a shorter time to recurrence (P = 0.049, 0.002 respectively) in patients with early stage HCC. Tumour-infiltrating Foxp3 + Tregs were related to chronic hepatitis B natural history in HCC (P = 0.012). Neither tumour-infiltrating CD8(+) T cells nor balance of intratumoural Tregs and CD8(+) T cells correlated with prognosis of HCC.

CONCLUSIONS

Increased Foxp3(+) Tregs may represent a prognostic predictor in patients with early stage HCC. The CHB natural history influenced density of tumour-infiltrating Tregs in hepatocellular carcinoma patients with chronic hepatitis B viruses infection.

Associations between cytotoxic T lymphocyte-associated antigen-4 polymorphisms and serum tumor necrosis factor-α and interferon-γ levels in patients with chronic hepatitis B virus infection

BACKGROUND

Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) polymorphism, which may affect host immune response including cytokines production, is thought to be associated with hepatitis B virus (HBV) infection. This study investigated the associations between CTLA4 polymorphism and serum tumor necrosis factor (TNF)-α and interferon (IFN)-γ levels in patients with chronic HBV infection.

METHODS

CTLA4 promoter -318C/T and exon 1 +49A/G polymorphisms and serum TNF-α and IFN-γ levels were determined in 172 patients with chronic HBV infection and 145 healthy controls.

RESULTS

The genotype of CTLA4 -318C/T polymorphism had no association to TNF-α and IFN-γ levels. Serum levels of TNF-α and IFN-γ in chronic HBV patients with +49GG genotype were lower than those with +49AG genotype (p = 0.030 and p = 0.042, respectively), and haplotypes -318C + 49A and -318C + 49G seemed to have no significant effects on TNF-α and IFN-γ levels.

CONCLUSIONS

CTLA4 +49GG genotype was associated to lower TNF-α and IFN-γ levels in patients with chronic HBV infection but this association was diminished by haplotype formation with -318C/T alleles, indicating that the influence of CTLA4 -318C/T and +49A/G polymorphisms on the susceptibility and disease progress of chronic HBV infection may not be effectuated by affecting TNF-α and IFN-γ secretion.

Circulating Tregs correlate with viral load reduction in chronic HBV-treated patients with tenofovir disoproxil fumarate

Limited response to current hepatitis B virus (HBV) drugs is possibly due to inadequate host cytotoxic cellular responses. Circulating Tregs have been shown to be associated with chronicity of HBV infection, but their profile during antiviral therapy has not been studied. We analyzed the frequency and effect of Tregs on cellular immune responses against HBV in 35 chronic hepatitis B eAg-ve and eAg+ve patients treated with tenofovir 300 mg/day. Frequency of Tregs and their modulatory role in cytokine-secreting cells were determined after stimulation with HBsAg or HBcAg in the absence or presence of Tregs and after blockage of PD-1/PDL-1 in peripheral blood mononuclear cells (PBMCs). Prior to therapy, eAg-ve patients had lower HBV DNA levels, reduced CD8 T cells, increased Tregs, and T cells expressing PD1. After 12 weeks of therapy, >2 log HBV viral reduction was observed in both groups, along with an increase frequencies of CD8 T cells in eAg-ve patients and increased expression of chemokine receptors/Toll-like receptors in both groups. PD-1 expression on CD8 cells in PBMCs was decreased in both groups during therapy but not on Tregs. In eAg-ve group, sustained increase of Tregs was observed till week 12, which declined at week 24. In both groups, after 24 weeks, depletion of CD4(+)CD25(+) Tregs from PBMCs enhanced HBV-specific T cell responses, and blockage of PD-1/PDL1 pathway did enhance pro-inflammatory cytokine production in eAg+ve patients but not in eAg-ve. We conclude that Tregs induced by HBV replication in vivo are expanded in eAg-ve patients more. Reduction in HBV DNA by tenofovir partially restored adaptive immune responses and also reduced the Tregs. Blockage of PD-1/PDL1, enhanced cytokine production in eAg+ve patients but not in eAg-ve, suggests that distinctly different immunologic mechanisms are involved in eAg+ve and eAg-ve patients.

Regulatory T cells in HBV and HCV liver diseases: implication of regulatory T lymphocytes in the control of immune response

IMPORTANCE OF THE FIELD

Hepatic cirrhosis is a frequent consequence of chronic hepatitis infection (HBV and HCV) or alcohol abuse and the most common cause of hepatocellular carcinoma (HCC). Currently, liver transplantation remains the only effective therapeutic approach for cirrhosis-related HCC patients. The evolution of the pathology strongly depends on immunological mechanisms.

AREAS COVERED IN THIS REVIEW

Despite the presence of specific T cells, viral chronic infection and continuous tumor growth suggest a failure of immune control. It appears that direct suppression of antiviral or antitumor effector cells by regulatory T cells plays a pivotal role in the impairment of immune response. Several types of regulatory T cells have been described, natural regulatory T cells (nTreg) and induced-type 1 regulatory T cells (Tr1) being the best characterized.

WHAT THE READER WILL GAIN

Currently, there is no evidence for a direct implication of regulatory T cells in the evolution of hepatitis, especially concerning chronic infection, cirrhosis late stage and HCC progress. However, recent studies show that regulatory T cells are implicated in the modulation of HBV- and HCV-associated immune response, thus, promoting HCC progress.

TAKE HOME MESSAGE

Therefore, nTreg and Tr1 cells seem to play an important role in the control of immune response leading to chronic hepatitis infection and progression of the pathology to cirrhosis and HCC.

Regulatory T cells suppress antigen-driven CD4 T cell reactivity following injury

Injury initiates local and systemic host responses and is known to increase CD4 Treg activity in mice and humans. This study uses a TCR transgenic T cell adoptive transfer approach and in vivo Treg depletion to determine specifically the in vivo influence of Tregs on antigen-driven CD4 T cell reactivity following burn injury in mice. We report here that injury in the absence of recipient and donor Tregs promotes high antigen-driven CD4 T cell expansion and increases the level of CD4 T cell reactivity. In contrast, CD4 T cell expansion and reactivity were suppressed significantly in injured Treg-replete mice. In additional experiments, we found that APCs prepared from burn- or sham-injured, Treg-depleted mice displayed significantly higher antigen-presenting activity than APCs prepared from normal mice, suggesting that Tregs may suppress injury responses by controlling the intensity of APC activity. Taken together, these findings demonstrate that Tregs can actively control the in vivo expansion and reactivity of antigen-stimulated, naïve CD4 T cells following severe injury.

Th17 cells: the emerging reciprocal partner of regulatory T cells in the liver

T helper cells that produce interleukin-17 (IL-17) (Th17 cells) have recently been identified as the third distinct subset of effector T cells, the differentiation of which depends on specific transcription nuclear factor retinoic acid-related orphan nuclear receptor-gammat. Emerging data have suggested that Th17 cells play an important role in innate immunity, adaptive immunity and autoimmunity. Interestingly, there is a reciprocal relationship between Th17 cells and regulatory T cells (Treg), not only in development, but also in their effector function. Transforming growth factor (TGF)-beta induces Treg-specific transcription factor Forkhead box P3(FOXP3), while the addition of IL-6 to TGF-beta inhibits the generation of Treg cells and induces Th17 cells. It is proposed that the fine balance between Th17 and Treg cells is crucial for maintenance of immune homeostasis. In addition to IL-6, other factors such as retinoic acid, rapamycin, or cytokines (e.g., IL-2 and IL-27) could dictate the balance between Th17 and Treg cells. Since Treg cells play an important role in hepatic immunity with overregulation in chronic viral hepatitis and hepatic carcinoma, and inadequate inhibition in autoimmune liver diseases, graft rejection and acute liver failure, it is reasonable to assume that Th17 cells may play a reciprocal role in these diseases. Thus, future research on the Treg/Th17 balance may provide an opportunity to illustrate the pathogenesis of hepatic inflammation and to explore new therapeutic targets for immune-related liver diseases.

Effector/memory but not naive regulatory T cells are responsible for the loss of concomitant tumor immunity

The phenomenon of concomitant tumor immunity involves a tumor-bearing host rejecting another similar tumor at a distant site and suggests the existence of tumor-specific immunity. Loss of this immunity may contribute to tumor metastasis. However, mechanisms underlying the loss of concomitant immunity are largely unknown. We set up a concomitant tumor immunity model in which this immunity is gradually lost as the primary tumor progresses. We found that CD8(+) T cells, especially tumor-infiltrating CD8(+) T cells, from mice that lost concomitant tumor immunity, possessed potent antitumor properties and strongly expressed effector molecules. Furthermore, effector/memory regulatory T cells (Treg cells, CD103(+)CD4(+)Foxp3(+) T cells) increased as the primary tumor progressed. They initially accumulated around the tumor and in the spleen at later points. Not only did these cells more greatly express killing molecules, they also suppressed the functions of tumor-bearing CD8(+) T cells in vitro and in vivo. Finally, we show that these effector/memory Treg cells inhibit concomitant tumor immunity in vivo. Taken together, data suggest that effector/memory Treg cells are responsible for the loss of concomitant tumor immunity associated with tumor progression.

Gene expression signatures of peripheral CD4+ T cells clearly discriminate between patients with acute and chronic hepatitis B infection

CD4+ T and regulatory T cells (Tregs) seem to play a key role in persistence of hepatitis B virus (HBV) infection. However, the molecular events by which Tregs exert their modulatory activity are largely unknown. The transcriptional profiles of CD4+ T cells of healthy controls (HCs) and patients affected by acute hepatitis B (AVH-B) or chronic hepatitis B (CHB) infection were established using a custom expression array consisting of 350 genes relevant for CD4+ T cell and Treg function. These studies were complemented by real-time reverse-transcription polymerase chain reaction. Peripheral blood mononuclear cells (PBMCs) were also analyzed for the presence of Tregs, which were more abundant in the acute stage of the disease (7%) than in HCs and CHB infection (HCs versus AVH-B, P = 0.003; AVH-B versus CHB, P = 0.04). One hundred eighteen genes (34%) intrinsically differentiate HBV-infected patients from HCs. Using gene ontology, we identified T cell receptor signaling and clusterization, mitogen-activated protein kinase kinase signaling, cell adhesion, cytokines and inflammatory responses, cell cycle/cell proliferation, and apoptosis as the most prominent affected modules. A higher expression of CCR1, CCR3, CCR4, CCR5, and CCR8 was seen in AVH-B than in CHB-infected patients and HCs. Annotation of the interconnected functional network of genes provided a unique representation of global immune activation during acute infection. Almost all genes were down-regulated in patients with CHB infection.

CONCLUSION

The fingerprints enable clear discrimination between patients suffering from AVH-B or CHB infection. The observed profiles suggest accumulation of effector T cells with a potential role in necro-inflammation during the acute stage. Subsequent down-regulated effector functions support the hypothesis of suppressed CD4+ effector T cells favoring viral persistence in the chronic infection stage.

Regulatory T cells differentially modulate the maturation and apoptosis of human CD8+ T-cell subsets

The balanced manifestation of effector functions and the generation of long-living memory cells is a hallmark of efficient CD8(+) T-cell response. Accumulating data pinpoint CD4(+) CD25(high) regulatory T (Treg) cells as a key factor for the inefficiency of CD8(+) T-cell responses in viral persistence. Little is known about the effects of Treg cells on the homeostasis of healthy donor CD8(+) T cells. The present study demonstrates that Treg cells exert differential effects on CD8(+) T-cell subsets. Treg cells inhibited mostly the polyclonal proliferation of CD27(-) effector cells compared with CD27(+) memory CD8(+) T cells. Moreover, they inhibited the polyclonal and antigen-driven differentiation of memory cells into functional effectors as defined by IFN-gamma secretion and induction of CD160 expression. Finally, Treg cells reduced the apoptosis of memory but not of effector and terminal effector cell populations. These effects were at least in part mediated by a decreased expression of PD-L1, but not of programmed death 1 (PD-1), on CD8(+) T cells after activation. Thus, in the setting of a healthy immune system, Treg cells fine-tune the memory/effector cell balance and promote the accumulation of long-living memory cells in case of strong stimulation.

Case-crossover study of hospitalization for acute hepatitis in Chinese herb users

BACKGROUND AND AIM

Despite the increase in popularity of herbal products, there is growing concern over potential health hazards caused by the Chinese herbal medicines (CHMs) that are regularly reimbursed under the National Health Insurance system in Taiwan. This study attempts to determine the association between CHM prescriptions and acute hepatitis-related hospitalizations.

METHODS

A case-crossover study was designed on 200,000 randomly selected individuals from the National Health Insurance Research Database who were then followed from 1997 to 2002. All medications taken in the 30- and 60-day periods prior to hospitalization were explored and compared with four control periods (the 180- and 360-day periods prior to and after the hospitalization). A conditional logistic regression model was then constructed to determine the odds of CHM being prescribed during these risk periods.

RESULTS

There were a total of 12 cases with nonviral, nonalcoholic hepatitis patients who took CHM prescriptions during the 30-day risk or control periods. After adjustment for conventional hepatotoxic drugs, the odds ratio during the 30-day risk period was 3.4 (95% confidence interval [CI]: 1.1, 9.8) for nonviral, nonalcoholic acute hepatitis. A detailed historical review of CHMs for each patient revealed that the odds ratio increased to 4.2 for those prescribed formulae containing Radix Paeoniae (95% CI: 1.1, 15.7) and Radix Glycyrrhizae (95% CI: 1.2, 15.2).

CONCLUSIONS

Chinese herbal users revealed a slightly increased risk of acute hepatitis. We therefore recommend pharmacovigilance and active surveillance for CHMs suspected with hepatotoxicity.

CD4+ CD25+ regulatory T cells: a therapeutic target for liver diseases

BACKGROUND

Regulatory T cells (Tregs) have been shown to play an important role in maintaining peripheral immune homeostasis by suppressing autoreactive and allergen-specific T cells and turning off the immune response after the pathogen has been cleared. However, in certain situations Tregs can impair effective immunity to some pathogens and tumour cells.

OBJECTIVE

To review the role of Tregs in liver pathology and to assess the potential to enhance or inhibit their function as applied to the treatment of liver disease.

METHODS

The literature was reviewed using standard indexing terms and incorporating publications up to and including those published in 2007.

RESULTS/CONCLUSIONS

Tregs are therapeutic targets for modulation in autoimmune disease and may provide new opportunities for application to human liver conditions.