Ming Shi

Circulating and Liver Resident CD4+CD25+ Regulatory T Cells Actively Influence the Antiviral Immune Response and Disease Progression in Patients with Hepatitis B

CD4+CD25+ regulatory T cells (Treg) have been shown to maintain immune tolerance against self and foreign Ags, but their role in persistent viral infection has not been well-defined. In this study, we investigated whether and where CD4+CD25+ Treg contribute to the development of chronic hepatitis B (CHB). One hundred twenty-one patients were enrolled, including 16 patients with acute hepatitis B, 76 with CHB, and 29 with chronic severe hepatitis B. We demonstrated that in chronic severe hepatitis B patients, the frequencies of CD4+CD25+ Treg in both PBMC and liver-infiltrating lymphocytes were significantly increased and there was a dramatic increase of FoxP3+-cell and inflammatory cell infiltration in the liver compared with healthy controls. In CHB patients, circulating CD4+CD25+ Treg frequency significantly correlates with serum viral load. In acute hepatitis B patients, circulating CD4+CD25+ Treg frequency was initially low and with time, the profile reversed to exhibit an increased number of circulating Treg in the convalescent phase and restored to normal levels upon resolution. In PBMC taken from infected patients, depletion of CD4+CD25+ Treg led to an increase of IFN-γ production by HBV-Ag-stimulated PBMC. In addition, CD4+CD25+ Treg were capable of suppressing proliferation of autologous PBMC mediated by HBV Ags, which probably reflects the generation of HBV-Ag-specific Treg in circulation and in the liver of HBV-infected patients. Together, our findings suggest that CD4+CD25+ Treg play an active role not only in modulating effectors of immune response to HBV infection, but also in influencing the disease prognosis in patients with hepatitis B.

Interleukin-17–producing CD4+ T cells increase with severity of liver damage in patients with chronic hepatitis B†

Interleukin‐17 (IL‐17)‐producing CD4+ T cells (Th17)‐mediated immune response has been demonstrated to play a critical role in inflammation‐associated disease; however, its role in chronic hepatitis B virus (HBV) infection remains unknown. Here we characterized peripheral and intrahepatic Th17 cells and analyzed their association with liver injury in a cohort of HBV‐infected patients including 66 with chronic hepatitis B (CHB), 23 with HBV‐associated acute‐on‐chronic liver failure (ACLF), and 30 healthy subjects as controls. The frequency of circulating Th17 cells increased with disease progression from CHB (mean, 4.34%) to ACLF (mean, 5.62%) patients versus healthy controls (mean, 2.42%). Th17 cells were also found to be largely accumulated in the livers of CHB patients. The increases in circulating and intrahepatic Th17 cells positively correlated with plasma viral load, serum alanine aminotransferase levels, and histological activity index. In vitro, IL‐17 can promote the activation of myeloid dendritic cells and monocytes and enhance the capacity to produce proinflammatory cytokines IL‐1β, IL‐6, tumor necrosis factor (TNF)‐α, and IL‐23 in both CHB patients and healthy subjects. In addition, the concentration of serum Th17‐associated cytokines was also increased in CHB and ACLF patients. Conclusion: Th17 cells are highly enriched in both peripheral blood and liver of CHB patients, and exhibit a potential to exacerbate liver damage during chronic HBV infection. (HEPATOLOGY 2009.)

PD-1 and PD-L1 upregulation promotes CD8(+) T-cell apoptosis and postoperative recurrence in hepatocellular carcinoma patients

Programmed death 1 (PD‐1) and its ligand (PD‐L1) play pivotal roles in regulating host immune responses. However, the inhibitory effects of this pathway on the function of cytotoxic CD8+ T lymphocytes, the main effector cells in hepatocellular carcinoma (HCC) patients, are not well defined. In this study, we characterized circulating and intratumor PD‐1/PD‐L1 expression and analyzed their association with disease progression in a cohort of hepatitis B virus‐infected patients, including 56 with HCC, 20 with liver cirrhosis (LC) and 20 healthy controls (HC). The frequency of circulating PD‐1+CD8+ T cells increased with disease progression from LC to HCC patients versus HC. Furthermore, tumor‐infiltrating effector CD8+ T cells showed a drastic increase in PD‐1 expression. These increases in circulating and intratumor PD‐1+CD8+ T cells could predict poorer disease progression and postoperative recurrence. Immunohistochemical staining showed that PD‐L1 expressing hepatoma cells and apoptotic infiltrating CD8+ T cells were both enriched in tumor sections. In vitro, CD8+ T cells induced PD‐L1 expression on hepatoma cells in an IFN‐γ–dependent manner, which in turn promoted CD8+ T cells apoptosis, and blocking PD‐L1 reversed this effect. Therefore, this study extends our knowledge of the role of the PD‐1/PD‐L1 pathway in tumor evasion and provides evidence for a new therapeutic target in HCC patients.

Immunomodulatory properties and therapeutic application of mesenchymal stem cells

Mesenchymal stem cells (MSCs) are multi‐potent progenitor cells that are isolated from the bone marrow and several adult organs and tissues. These cells possess remarkable immunosuppressive properties and can inhibit the proliferation and function of the major immune cell populations, including T cells, B cells and natural killer (NK) cells; modulate the activities of dendritic cells (DCs); and induce regulatory T cells both in vivo and in vitro. These unique properties make MSCs ideal candidates for clinical application as immunosuppressants. The immunomodulatory effect of MSCs is mediated by a non‐specific anti‐proliferative action of these cells, which is dependent on cell–cell contact or secreted soluble factors such as indoleamine 2,3‐dioxygenase (IDO), prostaglandin E2 (PGE2), nitric oxide (NO), histocompatibility leucocyte antigen‐G (HLA‐G), transforming growth factor (TGF)‐β, interferon (IFN)‐γ and interleukin (IL)‐1β. Considerable progress has been obtained in preclinical studies on MSCs, including those on their ability to activate allogeneic cells. This review examines the current understanding of the immunomodulatory properties of MSCs and its therapeutic implication for immune‐mediated diseases and transplant rejection.

Human umbilical cord mesenchymal stem cells improve liver function and ascites in decompensated liver cirrhosis patients.

Decompensated liver cirrhosis (LC), a life‐threatening complication of chronic liver disease, is one of the major indications for liver transplantation. Recently, mesenchymal stem cell (MSC) transfusion has been shown to lead to the regression of liver fibrosis in mice and humans. This study examined the safety and efficacy of umbilical cord‐derived MSC (UC‐MSC) in patients with decompensated LC. A total of 45 chronic hepatitis B patients with decompensated LC, including 30 patients receiving UC‐MSC transfusion, and 15 patients receiving saline as the control, were recruited; clinical parameters were detected during a 1‐year follow‐up period. No significant side‐effects and complications were observed in either group. There was a significant reduction in the volume of ascites in patients treated with UC‐MSC transfusion compared with controls (P < 0.05). UC‐MSC therapy also significantly improved liver function, as indicated by the increase of serum albumin levels, decrease in total serum bilirubin levels, and decrease in the sodium model for end‐stage liver disease scores. UC‐MSC transfusion is clinically safe and could improve liver function and reduce ascites in patients with decompensated LC. UC‐MSC transfusion, therefore, might present a novel therapeutic approach for patients with decompensated LC.

Human Mesenchymal Stem Cell Transfusion Is Safe and Improves Liver Function in Acute-on-Chronic Liver Failure Patients

Acute‐on‐chronic liver failure (ACLF) is a severe, life‐threatening complication, and new and efficient therapeutic strategies for liver failure are urgently needed. Mesenchymal stem cell (MSC) transfusions have been shown to reverse fulminant hepatic failure in mice and to improve liver function in patients with end‐stage liver diseases. We assessed the safety and initial efficacy of umbilical cord‐derived MSC (UC‐MSC) transfusions for ACLF patients associated with hepatitis B virus (HBV) infection. A total of 43 ACLF patients were enrolled for this open‐labeled and controlled study; 24 patients were treated with UC‐MSCs, and 19 patients were treated with saline as controls. UC‐MSC therapy was given three times at 4‐week intervals. The liver function, adverse events, and survival rates were evaluated during the 48‐week or 72‐week follow‐up period. No significant side effects were observed during the trial. The UC‐MSC transfusions significantly increased the survival rates in ACLF patients; reduced the model for end‐stage liver disease scores; increased serum albumin, cholinesterase, and prothrombin activity; and increased platelet counts. Serum total bilirubin and alanine aminotransferase levels were significantly decreased after the UC‐MSC transfusions. UC‐MSC transfusions are safe in the clinic and may serve as a novel therapeutic approach for HBV‐associated ACLF patients.

B7-H1 Up-Regulation on Myeloid Dendritic Cells Significantly Suppresses T Cell Immune Function in Patients with Chronic Hepatitis B

Although dysfunctional dendritic cells contribute to inadequate adaptive immunity in chronic hepatitis B (CHB), underlying molecular mechanisms remain largely undefined. In this study, we examined B7-H1 expression on circulating myeloid dendritic cells (mDCs) in 46 CHB patients, 10 autoimmune hepatitis patients, and 10 healthy subjects as control. We found that B7-H1 expression is significantly up-regulated on circulating mDCs of CHB and autoimmune hepatitis patients compared with healthy individuals. The B7-H1 up-regulation was significantly correlated with an elevation of serum alanine aminotransaminase levels and plasma viral load. In addition, in vitro, both IFN-α and IFN-γ could strongly stimulate mDCs to express B7-H1. More importantly, elevated B7-H1 expression is also closely associated with the suppression of T cell immune function. In vitro blockade of B7-H1 signaling could not only down-regulate IL-10 and up-regulate IL-12 production by mDCs, but also enhance mDC-mediated allostimulatory capacity and cytokine production of T cells. Blockade of B7-H1 signaling could improve hepatitis B c Ag-pulsed monocyte-derived DC-induced IFN-γ production by autologous hepatitis B virus-specific T cells. These new findings suggested that chronic inflammation may contribute to B7-H1 up-regulation on mDCs in CHB patients, which potentially cause defective hepatitis B virus-specific T cell function and viral persistence. Our findings further support the notion that the blockade of B7-H1 may represent a novel therapeutic approach for this disease.

The decrease of regulatory T cells correlates with excessive activation and apoptosis of CD8+ T cells in HIV-1-infected typical progressors, but not in long-term non-progressors

Persistent HIV infection results in a decrease in absolute counts of CD4+ CD25+ regulatory T cells (Treg). To investigate the role of decreased Treg counts in the regulation of excessive activation and apoptosis of CD8+ T cells in human immunodeficiency virus (HIV)‐1 infection, we characterized Treg in 83 HIV‐1‐infected individuals, including 19 long‐term non‐progressors (LTNPs) and 51 typical progressors (TPs) who were treatment‐naïve, and 13 AIDS patients on highly active antiretroviral therapy (HAART), of whom nine were complete responders (CRs) and the remaining four were non‐responders (NRs) to the treatment. TPs but not LTNPs had a significant decrease in absolute counts of circulating Treg, which was inversely correlated with the activation and apoptosis of CD8+ T cells. Efficient HAART was found to increase Treg counts in CR patients and temper the excessive activation and apoptosis of CD8+ T cells. Moreover, isolated Treg significantly inhibited the spontaneous and anti‐CD3‐induced apoptosis of CD8+ T cells in a dose‐dependent manner in vitro. Thus, our findings indicate that the decrease in Treg closely correlates with the increase in apoptotic CD8+ T cells and disease progression in chronic HIV‐1 infection, and that Treg may play a key role in maintaining the balance between the amount and quality of CD8+ T cells in HIV‐1 infection. Manipulation of Treg function may be a promising strategy for immune therapy of this disease.

A pilot study of umbilical cord‐derived mesenchymal stem cell transfusion in patients with primary biliary cirrhosis

BACKGROUND AND AIM Ursodeoxycholic acid (UDCA) treatment is an effective medical therapy for patients with primary biliary cirrhosis (PBC); however, 40% of PBC patients show an incomplete response to the UDCA therapy. This study aimed to investigate the safety and efficacy of umbilical cord-derived mesenchymal stem cell (UC-MSC) transfusion in PBC patients with an incomplete response to UDCA. METHODS We conducted a single-arm trial that included seven PBC patients with a suboptimal response to UDCA treatment. UC-MSCs were first cultured, and then 0.5 × 10(6) cells/kg body weights were infused through a peripheral vein. UC-MSCs were given three times at 4-week intervals, and patients were followed up for 48 weeks. Primary outcomes were to evaluate the safety and feasibility of UC-MSC treatment, and secondary outcomes were to evaluate liver functions and patients quality of life. RESULTS No obvious side-effects were found in the patients treated with UC-MSCs. Symptoms such as fatigue and pruritus were obviously alleviated in most patients after UC-MSC treatment. There was a significant decrease in serum alkaline phosphatase and γ-glutamyltransferase levels at the end of the follow-up period as compared with baseline. No significant changes were observed in serum alanine aminotransferase, aspartate aminotransferase, total bilirubin, albumin, prothrombin time activity, international normalized ratio, or immunoglobulin M levels. The Mayo risk score, a prognostic index, was also stable during the treatment and follow-up period. CONCLUSIONS UC-MSC transfusion is feasible and well tolerated in patients with PBC who respond only partially to UDCA treatment, thus representing a novel therapeutic approach for patients in this subgroup. A larger, randomized controlled cohort study is warranted to confirm the clinical efficacy of UC-MSC transfusion.

Implications of the immunoregulatory functions of mesenchymal stem cells in the treatment of human liver diseases.

Transplantation of mesenchymal stem cells (MSCs) has been recently studied in animal models, and in clinical trials of patients with fulminant hepatic failure, end-stage liver diseases and inherited metabolic disorders. Modulatory cytokines produced by MSCs can inhibit immunocyte proliferation and migration to the liver, thereby attenuating inflammatory injury and reducing hepatocyte apoptosis. In addition, MSCs play an important role in regressing liver fibrosis and in supporting the function, proliferation and differentiation of endogenous hepatocytes under appropriate conditions. Although remarkable progress has been achieved in basic and clinical MSC studies, optimal therapeutic regimens for the clinical application of MSCs, such as optimal doses, transplantation routine and interval period for transplantation, need to be elucidated in detail. Furthermore, the long-term safety and therapeutic efficacy of MSC transplantation should be evaluated in future clinical trials. This review summarizes our current understanding of the immunomodulatory effects of MSC therapies on human liver diseases.