Negative regulation of the interferon response by an interferon-induced long non-coding RNA.

Long non-coding RNAs (lncRNAs) play critical roles in diverse cellular processes; however, their involvement in many critical aspects of the immune response including the interferon (IFN) response remains poorly understood. To address this gap, we compared the global gene expression pattern of primary human hepatocytes before and at three time points after treatment with IFN-α. Among ∼ 200 IFN-induced lncRNAs, one transcript showed ∼ 100-fold induction. This RNA, which we named lncRNA-CMPK2, was a spliced, polyadenylated nuclear transcript that was induced by IFN in diverse cell types from human and mouse. Similar to protein-coding IFN-stimulated genes (ISGs), its induction was dependent on JAK-STAT signaling. Intriguingly, knockdown of lncRNA-CMPK2 resulted in a marked reduction in HCV replication in IFN-stimulated hepatocytes, suggesting that it could affect the antiviral role of IFN. We could show that lncRNA-CMPK2 knockdown resulted in upregulation of several protein-coding antiviral ISGs. The observed upregulation was caused by an increase in both basal and IFN-stimulated transcription, consistent with loss of transcriptional inhibition in knockdown cells. These results indicate that the IFN response involves a lncRNA-mediated negative regulatory mechanism. lncRNA-CMPK2 was strongly upregulated in a subset of HCV-infected human livers, suggesting a role in modulation of the IFN response in vivo.

Accessory cell dependent NK cell mediated PBMC IFN-gamma production is defective in HIV infection.

HCV and HIV infections impair dendritic cell function. We evaluated the impact of HCV, HIV, and HCV-HIV infection on MDC-NK interactions by analyzing CD3 depleted PBMC for NK cell IFN-gamma in response to IL-12 or poly (I:C). Purified MDC and NK cells were analyzed for TLR ligand-dependent, MDC-dependent NK activity. In HIV infection, IFN-gamma production by CD3 depleted PBMC was reduced in response to poly (I:C), while response to IL-12 was intact in HCV and HIV infections. Poly (I:C) induced activity was dependent on MDC and partially dependent on IL-12, consistent with accessory cell help. In purified MDC-NK co-cultures, MDC dependent NK IFN-gamma and Granzyme B was intact in both HCV and HIV infections, while MDC numerical defects were observed in HIV infection. These data indicate that during viral infection with HIV, accessory cell dependent NK function in the periphery is impaired. This impairment may be related to the identified MDC numerical defect.

HIV coinfection impairs CD28-mediated costimulation of hepatitis C virus-specific CD8 cells.

BACKGROUND: During human immunodeficiency virus (HIV) infection, reduced proportions of CD8 cells express CD28, the key costimulatory molecule for lymphocyte activation. However, it is unclear whether reduced CD28 expression affects immune responses to non-HIV antigens, potentially contributing to susceptibility to opportunistic infection. METHODS: We measured CD4- and CD8-specific interferon- gamma responses to hepatitis C virus (HCV) peptide pools in subjects with chronic HCV monoinfection (n=14), in subjects with chronic HCV/HIV coinfection (n=15), and in healthy control subjects (n=10) by enzyme-linked immunospot assay in the presence and absence of CD28 costimulation. RESULTS: Anti-CD28 agonist increased the cumulative frequency of HCV-specific CD4 cell responses in the subjects with HCV monoinfection and in those with HCV/HIV coinfection. In contrast, anti-CD28 agonist increased the breadth and cumulative frequency of HCV-specific CD8 cell responses only in the subjects with HCV monoinfection. Additionally, in the presence of anti-CD28 agonist, the proportion of subjects responding, the cumulative frequency, and the breadth of reactive CD8 cells were greater among the subjects with HCV monoinfection than among those with HCV/HIV coinfection. Finally, the HCV/HIV-coinfected subjects had lower proportions of CD8 cells that expressed CD28. CONCLUSIONS: These results indicate that, during HCV/HIV coinfection, memory-effector CD8 cells have reduced responsiveness to CD28 costimulation. This appears to reflect a global effect that HIV has on the activation or differentiation state of CD8 cells that are responsive to other microbial pathogens. This functional defect has implications for the pathogenesis of HCV/HIV coinfection.

A Phase I/II study evaluating escalating doses of recombinant human albumin-interferon-alpha fusion protein in chronic hepatitis C patients who have failed previous interferon-alpha-based therapy.

Albumin-interferon-alpha (IFN-alpha) is a novel 85.7-kDa recombinant protein consisting of IFN-alpha that is genetically fused to human serum albumin. In this Phase I/II, multicentre, open-label study, we evaluated the safety and tolerability, pharmacokinetics and pharmacodynamics of albumin-IFN-alpha in IFN-alpha-experienced patients with chronic hepatitis C. Albumin-IFN-alpha was administered in 22 escalating doses (7-900 microg) in a single injection or in two injections 14 days apart. In the 119 patients studied, there were no discontinuations because of adverse events, and albumin-IFN-alpha had a favourable safety profile at doses up to 900 microg. The most common adverse events were headache (56%), fatigue (52%), injection site erythema (38%), arthralgias (32%) and pyrexia (27%). Reduced clearance resulted in a mean elimination half-life of 159 h, which supports dosing at 2- to 4-week intervals. Induction of the IFN-specific gene OAS1 was maintained for > or = 28 days following a single injection of albumin-IFN-alpha at doses of > or = 40 microg. Dose-dependent antiviral activity was observed in this IFN-alpha-experienced study population. Antiviral activity of > or = 1.0-log reductions in HCV RNA was observed in 47% (37/78) of patients in the 120- to 900-microg cohorts and in 59% (16/27) in the 400- to 900-microg double-injection cohorts. These results support further clinical studies of albumin-IFN-alpha for the treatment of patients with chronic hepatitis C.

HIV long-term non-progressors maintain brisk CD8 T cell responses to other viral antigens.

OBJECTIVE: To examine the specificity of heightened CD8 cell responses in HIV-1-infected long-term non-progressors. DESIGN: Cross-sectional study examining CD8 cell responses to hepatitis C virus (HCV) peptides in HCV-HIV LTNP (n = 6), HCV-HIV progressors (n = 11), HCV singly infected patients (n = 32), HCV singly infected patients with self-limited disease (n = 10), HIV singly infected progressors (n = 7) and HCV-negative, HIV-negative controls (n = 10). METHODS: The frequency of HCV-reactive interferon gamma-producing cells in peripheral blood was assayed by enzyme linked immunospot assay using a panel of 61 HCV-1-derived peptides. RESULTS: Five of six HCV-HIV LTNP had HCV-specific CD8 responses. In contrast, responses were observed in 2 of 32 HCV singly infected patients, 2 of the 10 HCV singly infected patients with self-limited disease, and 0 of 11 HCV-HIV progressors (P < 0.001). Both frequency of HCV-specific CD8 cells and number of HCV peptides recognized were greater in HCV-HIV LTNP than in other groups. CONCLUSIONS: HIV-infected LTNP maintain heightened CD8 cell responses to HCV in addition to heightened HIV specific responses. Common mechanisms may underlie preservation of CD8 immune responses in these individuals. An improved understanding of these mechanisms will help to gain insight into protective antiviral immunity as well as to the means whereby these viruses impair host defenses.

Gastroesophageal reflux disease-associated esophagitis induces endogenous cytokine production leading to motor abnormalities.

BACKGROUND & AIMS: Gastroesophageal reflux disease is a condition frequently associated with esophagitis and motor abnormalities. Recent evidence suggests that proinflammatory cytokines, such as interleukin (IL)-1beta and IL-6, may be implicated because they reduce esophageal muscle contractility, but these results derive from in vitro or animal models of esophagitis. This study used human esophageal cells and tissues to identify the cellular source of cytokines in human esophagitis investigate whether cytokines can be induced by gastric refluxate, and examine whether esophageal tissue- or cell-derived mediators affect muscle contractility. METHODS: Endoscopic mucosal biopsy specimens were obtained from patients with and without esophagitis, organ-cultured, and undernatants were assessed for cytokine content. The cytokine profile of esophageal epithelial, fibroblast, and muscle cells was analyzed, and esophageal mucosa and cell products were tested in an esophageal circular muscle contraction assay. RESULTS: The mucosa of esophagitis patients produced significantly greater amounts of IL-1beta and IL-6 compared with those of control patients. Cultured esophageal epithelial cells produced IL-6, as did fibroblasts and muscle cells. Epithelial cells exposed to buffered, but not denatured, gastric juice produced IL-6. Undernatants of mucosal biopsy cultures from esophagitis patients reduced esophageal muscle contraction, as did supernatants from esophageal epithelial cell cultures. CONCLUSIONS: The human esophagus produces cytokines capable of reducing contractility of esophageal muscle cells. Exposure to gastric juice is sufficient to stimulate esophageal epithelial cells to produce IL-6, a cytokine able to alter esophageal contractility. These results indicate that classic cytokines are important mediators of the motor disturbances associated with human esophageal inflammation.

Cost-effectiveness of hematologic growth factors for anemia occurring during hepatitis C combination therapy.

In hepatitis C virus (HCV)-infected patients who develop anemia during combination therapy, erythropoietic growth factors maintain higher drug treatment levels compared to ribavirin dose reduction, which may lead to an increase in treatment response rates. This study estimated the cost-effectiveness of growth factor therapy in maintaining anemic HCV-infected patients on target drug levels during combination therapy. A decision analysis using a Markov model was developed with 7 health states: Sustained viral response, chronic HCV, compensated cirrhosis, decompensated cirrhosis, hepatocellular carcinoma, liver transplantation, and death. Data sources included population-based studies of growth factor therapy, previously published estimates of costs and natural history of hepatitis C, and recent prospective studies. Our reference case was a 45-year-old Caucasian man with HCV infection (genotype 1, 2, or 3) who developed anemia while undergoing combination therapy with ribavirin and pegylated interferon. We compared growth factor injections (darbepoetin alpha or epoetin alpha) during combination therapy with standard ribavirin dose reduction. Compared to a ribavirin dose reduction strategy, the cost of darbepoetin per additional quality-adjusted life-year was 34,793 dollars for genotype 1 and 33,832 dollars for genotypes 2 or 3 versus 60,600 dollars and 64,311 dollars for epoetin. For all genotypes, the results were sensitive to changes in the cure rates of HCV therapy, the utility of chronic HCV, the costs of growth factors, and the age at which therapy is begun. In conclusion, use of erythropoietic growth factors, specifically darbepoetin, for patients with anemia occurring during HCV combination therapy appears to be cost-effective for genotypes 1, 2, or 3.

Smoking and increased severity of hepatic fibrosis in primary biliary cirrhosis: A cross validated retrospective assessment.

An epidemiological association between cigarette smoking and primary biliary cirrhosis (PBC) has been demonstrated. Our aim was to determine the relationship between smoking and severity of liver fibrosis at presentation in patients with PBC. All patients with PBC seen at the three major teaching hospitals of Case Western Reserve University between October 1998 and December 2005 were identified. Data obtained at the time of the first evaluation leading to the PBC diagnosis on 97 patients were collected. The cumulative number of cigarette packs smoked per year (pack-years) was calculated. Advanced histological disease was defined as Ludwig stages 3 or 4. Analyses were performed to determine associations between advanced histological disease, smoking and other variables related to liver fibrosis. Smoking history was more common (P = .0008) in patients with advanced histological disease at presentation compared to those with early disease. Among smokers, mean lifetime tobacco consumption was higher (P = .04) in cases with advanced histological disease at presentation (30 pack-years) compared to cases with early disease (17 pack-years). Logistic regression demonstrated a significant association between a lifetime tobacco consumption of > or =10 pack-years and advanced histological disease at presentation (OR = 13.3). The association remained significant after adjusting for age, gender, and alcohol intake. The validity of these results was corroborated by cross-validation in an independent confirmatory set of 172 patients with PBC. In conclusion, smoking may accelerate the progression of PBC. This could be induced by exposure to chemicals in cigarette smoke.

Comprehensive determinant mapping of the hepatitis C-specific CD8 cell repertoire reveals unpredicted immune hierarchy.

While CD8 cells are thought to play an important role in the control hepatitis C infection, low frequencies of virus-specific cells and high numbers of potential determinants have made it challenging to obtain direct and comprehensive data regarding fine specificity and clonal size of the CD8 cells involved. Most assays suited for measuring CD8 cell frequencies require prior knowledge of immune dominant peptides. While there are excellent algorithms for predicting MHC-peptide binding strength for particular class I alleles, it is unknown how accurate these algorithms are in predicting the actual determinant recognized in an individual coexpressing other class I alleles. We used a high throughput ELISPOT approach to test for responses to every possible 9-mer determinant within the 191 residue hepatitis C core protein in addition to 61 previously defined CD8 cell determinants. The amino acid sequence of each determinant recognized was compared with HLA-binding predictions for the expressed class I alleles. These data show feasibility for and importance of comprehensive direct ex vivo monitoring, an approach which should facilitate design of antiviral immunotherapeutic strategies.

Selective impairments in dendritic cell-associated function distinguish hepatitis C virus and HIV infection.

Impaired APC functions may play important roles in chronicity of hepatitis C virus (HCV) and HIV infections. To investigate the separate and combined effects of HCV and HIV infection on immature dendritic cells (DCs), we evaluated myeloid-derived DC (MDC) and plasmacytoid-derived DC (PDC) frequencies and functions, measured by Toll-like receptor ligand-induced IFN-alpha and IL-12, in healthy controls and subjects with chronic HCV, HIV, and HCV-HIV infection. To evaluate the relation between innate and adaptive immunity, we measured HCV-specific IFN-gamma-producing T cell frequency. MDC frequencies tended to be reduced in HIV infection (1.8-fold), while PDC frequencies were minimally reduced in HCV infection (1.4-fold). In contrast, a striking reduction in non-PDC-associated IFN-alpha production was observed in HIV-infected subjects (17-fold), while PDC-associated IFN-alpha production was markedly reduced in HCV-infected subjects (20-fold). Both non-PDC and PDC functions were impaired in HCV-HIV coinfection. MDC-associated IL-12 production was markedly reduced in both HCV and HIV-infected subjects (over 10-fold). Functional defects were attenuated with slowly progressive HIV infection. The proportion of subjects with HCV-specific T cell responses, and the number of Ags recognized were reduced in HCV-HIV subjects as compared with HCV singly infected subjects. A positive association was observed between MDC-associated IL-12 production and HCV-specific T cell frequency in HCV-infected subjects. These results indicate that immature DC function is dysregulated in HIV and HCV infections, but differentially, and that these defects are attenuated in slowly progressive HIV infection. These selectively different impairments may contribute to the reduced adaptive immune response to HCV in HCV-HIV coinfection.