Lymphocyte subset characterization associated with persistent hepatitis C virus infection and subsequent progression of liver fibrosis

Metabolic Profile as a Potential Modifier of Long-Term Radiation Effects on Peripheral Lymphocyte Subsets in Atomic Bomb Survivors

Immune system impairments reflected by the composition and function of circulating lymphocytes are still observed in atomic bomb survivors, and metabolic abnormalities including altered blood triglyceride and cholesterol levels have also been detected in such survivors. Based on closely related features of immune and metabolic profiles of individuals, we investigated the hypothesis that long-term effects of radiation exposure on lymphocyte subsets might be modified by metabolic profiles in 3,113 atomic bomb survivors who participated in health examinations at the Radiation Effect Research Foundation, Hiroshima and Nagasaki, in 2000-2002. The lymphocyte subsets analyzed involved T-, B- and NK-cell subsets, and their percentages in the lymphocyte fraction were assessed using flow cytometry. Health examinations included metabolic indicators, body mass index, serum levels of total cholesterol, high-density lipoprotein cholesterol, C-reactive protein and hemoglobin A1c, as well as diabetes and fatty liver diagnoses. Standard regression analyses indicated that several metabolic indicators of obesity/related disease, particularly high-density lipoprotein cholesterol levels, were positively associated with type-1 helper T- and B-cell percentages but were inversely associated with naïve CD4 T and NK cells. A regression analysis adjusted for high-density lipoprotein cholesterol revealed a radiation dose relationship with increasing NK-cell percentage. Additionally, an interaction effect was suggested between radiation dose and C-reactive protein on B-cell percentage with a negative coefficient of the interaction term. Collectively, these findings suggest that radiation exposure and subsequent metabolic profile changes, potentially in relationship to obesity-related inflammation, lead to such long-term alterations in lymphocyte subset composition. Because this study is based on cross-sectional and exploratory analyses, the implications regarding radiation exposure, metabolic profiles and circulating lymphocytes warrant future longitudinal and molecular mechanistic studies.

Cultured Mycelium Cordyceps sinensis allevi¬ates CCl4-induced liver inflammation and fibrosis in mice by activating hepatic natural killer cells

AIM

Recent evidence shows that cultured mycelium Cordyceps sinensis (CMCS) effectively protects against liver fibrosis in mice. Here, we investigated whether the anti-fibrotic action of CMCS was related to its regulation of the activity of hepatic natural killer (NK) cells in CCl4-treated mice.

METHODS

C57BL/6 mice were injected with 10% CCl4 (2 mL/kg, ip) 3 times per week for 4 weeks, and received CMCS (120 mg·kg(-1)·d(-1), ig) during this period. In another part of experiments, the mice were also injected with an NK cell-deleting antibody ASGM-1 (20 μg, ip) 5 times in the first 3 weeks. After the mice were sacrificed, serum liver function, and liver inflammation, hydroxyproline content and collagen deposition were assessed. The numbers of hepatic NK cells and expression of NKG2D (activation receptor of NK cells) on isolated liver lymphocytes were analyzed using flow cytometry. Desmin expression and cell apoptosis in liver tissues were studied using desmin staining and TUNEL assay, respectively. The levels of α-SMA, TGF-β, RAE-1δ and RAE-1ε in liver tissues were determined by RT-qPCR.

RESULTS

In CCl4-treated mice, CMCS administration significantly improved liver function, attenuated liver inflammation and fibrosis, and increased the numbers of hepatic NK cells and expression level of NKG2D on hepatic NK cells. Furthermore, CMCS administration significantly decreased desmin expression in liver tissues, and increased TUNEL staining adjacent to hepatic stellate cells. Injection with NK cell-deleting ASGM-1 not only diminished the numbers of hepatic NK cells, but also greatly accelerated liver inflammation and fibrosis in CCl4-treated mice. In CCl4-treated mice with NK cell depletion, CMCS administration decelerated the rate of liver fibrosis development, and mildly upregulated the numbers of hepatic NK cells but without changing NKG2D expression.

CONCLUSION

CMCS alleviates CCl4-induced liver inflammation and fibrosis via promoting activation of hepatic NK cells. CMCS partially reverses ASGM-1-induced depletion of hepatic NK cells.

Natural killer and natural killer T cells in liver fibrosis

The liver lymphocyte population is enriched with natural killer (NK) cells, which play a key role in host defense against viral infection and tumor transformation. Recent evidence from animal models suggests that NK cells also play an important role in inhibiting liver fibrosis by selectively killing early or senescence activated hepatic stellate cells (HSCs) and by producing the anti-fibrotic cytokine IFN-γ. Furthermore, clinical studies have revealed that human NK cells can kill primary human HSCs and that the ability of NK cells from HCV patients to kill HSCs is enhanced and correlates inversely with the stages of liver fibrosis. IFN-α treatment enhances, while other factors (e.g., alcohol, TGF-β) attenuate, the cytotoxicity of NK cells against HSCs, thereby differentially regulating liver fibrogenesis. In addition, the mouse liver lymphocyte population is also enriched for natural killer T (NKT) cells, whereas human liver lymphocytes have a much lower percentage of NKT cells. Many studies suggest that NKT cells promote liver fibrogenesis by producing pro-fibrotic cytokines such as IL-4, IL-13, hedgehog ligands, and osteopontin; however, NKT cells may also attenuate liver fibrosis under certain conditions by killing HSCs and by producing IFN-γ. Finally, the potential for NK and NKT cells to be used as therapeutic targets for anti-fibrotic therapy is discussed. This article is part of a Special Issue entitled: Fibrosis: Translation of basic research to human disease.

Up-regulation of FOXP3 and induction of suppressive function in CD4+ Jurkat T-cells expressing hepatitis C virus core protein

HCV (hepatitis C virus) infection is a serious health care problem that affects more than 170 million people worldwide. Viral clearance depends on the development of a successful cellular immune response against the virus. Interestingly, such a response is altered in chronically infected patients, leading to chronic hepatitis that can result in liver fibrosis, cirrhosis and hepatocellular carcinoma. Among the mechanisms that have been described as being responsible for the immune suppression caused by the virus, Treg-cells (regulatory T-cells) are emerging as an essential component. In the present work we aim to study the effect of HCV-core protein in the development of T-cells with regulatory-like function. Using a third-generation lentiviral system to express HCV-core in CD4+ Jurkat T-cells, we describe that HCV-core-expressing Jurkat cells show an up-regulation of FOXP3 (forkhead box P3) and CTLA-4 (cytotoxic T-lymphocyte antigen-4). Moreover, we show that HCV-core-transduced Jurkat cells are able to suppress CD4+ and CD8+ T-cell responses to anti-CD3 plus anti-CD28 stimulation.