The influence of North American Aboriginal ethnicity on pro-inflammatory and anti-inflammatory cytokine responses to IFN-alpha

The Influence of Hepatitis C Viral Loads on Natural Killer Cell Function

Background

Hepatitis C virus (HCV) infection has a high rate of chronicity, attributable to its capacity to alter host immunity, including natural killer (NK) cell function. In this study, the interaction between NK cell activity and HCV viral load was investigated.

Methods

Peripheral blood NK cells were examined for cytotoxicity and interferon (IFN)-γ expression in HCV infected low (LVL, < 800,000 IU/mL, n = 10) and high (HVL, > 800,000 IU/mL, n = 13) viral load patient cohorts.

Results

Spontaneous NK cell cytotoxicity was more robust in the LVL cohort resulting in a negative correlation with viral loads (spontaneous, r = -0.437, P = 0.037; IFN-α activated, r = -0.372, P = 0.081). Although the percent of IFN-γ+ NK cells did not associate with viral load, within the LVL cohort there was a marked increase in IFN-γ+ NK cells upon IFN-α activation relative to medium alone (P < 0.01). To examine the inability of NK cells derived from HVL patients to be further activated, the expression of the exhaustion marker programmed cell death protein (PD)-1 was evaluated. PD-1 expression upon NK cell activation correlated with viral load (r = 0.649, P = 0.009). In addition, HCV proteins upregulated PD-1 expression in vitro (P < 0.05), suggesting that HCV can directly promote NK cell exhaustion. Cells from HVL patients were also more likely to produce IFN-γ in response to HCV core protein. The finding that NK cell PD-1 and IFN-γ expression are linked (r = 0.542, P < 0.05) suggests that increased IFN-γ levels may induce PD-1 as a negative feedback mechanism.

Conclusions

High HCV loads appear to promote NK exhaustion in chronic HCV infection.

Circulating and inducible IL-32α in chronic hepatitis C virus infection

Background: Interleukin 32 (IL-32) is a recently described pro-inflammatory cytokine implicated in chronic hepatitis C virus (HCV)-related inflammation and fibrosis. IL-32α is the most abundant IL-32 isoform. Methods: Circulating IL-32α levels were documented in patients with chronic HCV infections ( n = 31) and compared with individuals who spontaneously resolved HCV infection ( n = 14) and HCV-naive controls ( n = 20). In addition, peripheral blood mononuclear cells (PBMC) from the chronic HCV ( n = 12) and HCV-naive ( n = 9) cohorts were investigated for responses to HCV core and non-structural (NS)3 protein induced IL-32α production. Finally, correlations between IL-32α levels, hepatic fibrosis and subsequent responses to interferon-based therapy were documented in patients with chronic HCV. Results: Circulating IL-32α levels in patients with chronic HCV were similar to those of spontaneously resolved and HCV-naive controls. HCV protein induced IL-32α responses were similar in chronic HCV patients and HCV-naive controls. In patients with chronic HCV, serum IL-32α levels correlated with worsening METAVIR fibrosis (F) scores from F0 to F3 ( r = 0.596, P < 0.001) as did NS3 induced IL-32α responses ( r = 0.837, P < 0.05). However, these correlations were not sustained with the inclusion of IL-32α levels at F4 scores, suggesting events at F4 interfere with IL-32α synthesis or release. In chronic HCV patients who underwent treatment ( n = 28), baseline in vivo and in vitro induced IL-32α concentrations were not predictive of therapeutic outcomes. Conclusions: IL-32α activity is associated with worsening fibrosis scores in non-cirrhotic, chronic HCV patients.

Circulating and inducible IL-32α in chronic hepatitis C virus infection

Background: Interleukin 32 (IL-32) is a recently described pro-inflammatory cytokine implicated in chronic hepatitis C virus (HCV)-related inflammation and fibrosis. IL-32α is the most abundant IL-32 isoform. Methods: Circulating IL-32α levels were documented in patients with chronic HCV infections ( n = 31) and compared with individuals who spontaneously resolved HCV infection ( n = 14) and HCV-naive controls ( n = 20). In addition, peripheral blood mononuclear cells (PBMC) from the chronic HCV ( n = 12) and HCV-naive ( n = 9) cohorts were investigated for responses to HCV core and non-structural (NS)3 protein induced IL-32α production. Finally, correlations between IL-32α levels, hepatic fibrosis and subsequent responses to interferon-based therapy were documented in patients with chronic HCV. Results: Circulating IL-32α levels in patients with chronic HCV were similar to those of spontaneously resolved and HCV-naive controls. HCV protein induced IL-32α responses were similar in chronic HCV patients and HCV-naive controls. In patients with chronic HCV, serum IL-32α levels correlated with worsening METAVIR fibrosis (F) scores from F0 to F3 ( r = 0.596, P < 0.001) as did NS3 induced IL-32α responses ( r = 0.837, P < 0.05). However, these correlations were not sustained with the inclusion of IL-32α levels at F4 scores, suggesting events at F4 interfere with IL-32α synthesis or release. In chronic HCV patients who underwent treatment ( n = 28), baseline in vivo and in vitro induced IL-32α concentrations were not predictive of therapeutic outcomes. Conclusions: IL-32α activity is associated with worsening fibrosis scores in non-cirrhotic, chronic HCV patients.

Nonalcoholic Fatty Liver Disease in Canadian First Nations and Non-First Nations Patients

Background. Features of nonalcoholic fatty liver disease (NAFLD) have yet to be described in the Canadian First Nations (FN) population. The aim of this study was to compare the prevalence, severity, and outcome of NAFLD in FN versus non-FN patients at an urban, tertiary care centre. Methods. Adults with NAFLD and no additional liver disease were identified in a prospectively derived database at the University of Manitoba. Demographic, clinical, laboratory, imaging, and histologic data were analyzed. Results. 482 subjects fulfilled diagnostic criteria for NAFLD, including 33 (7%) FN. Aside from rural residence, diabetes and cholestasis being more common in FN patients, the ages, gender distributions, clinical and radiologic features, and liver enzyme/function test results were similar in the two cohorts. Noninvasive tests of fibrosis (APRI and NAFLD fibrosis scores) were also similar in the two cohorts. There were no significant differences in liver enzyme or function tests in either cohort after approximately three years of follow-up. Conclusion. Compared to the prevalence of FN persons in the general population of this study site (10-15%), FN patients were underrepresented in this NAFLD population. The severity and progression of liver disease in FN patients appear to be similar to those in non-FN patients.

Favourable IFNL3 genotypes are associated with spontaneous clearance and are differentially distributed in Aboriginals in Canadian HIV-hepatitis C co-infected individuals

Canadian Aboriginals are reported to clear Hepatitis C (HCV) more frequently. We tested the association of spontaneous clearance and three single nucleotide polymorphisms (SNPs) near the Interferon-lambda 3 (IFNL3) gene (rs12979860, rs8099917, functional variant rs8103142) and compared the SNP frequencies between HIV-HCV co-infected whites and Aboriginals from the Canadian Co-infection Cohort. HCV treatment-naïve individuals with at least two HCV RNA tests were included (n = 538). A spontaneous clearance case was defined as someone with two consecutive HCV RNA-negative tests, at least six months apart. Data were analyzed using Cox proportional hazards adjusted for sex and ethnicity. Advantageous variants and haplotypes were more common in Aboriginals than Caucasians: 57% vs. 46% had the rs12979860 CC genotype, respectively; 58% vs. 48%, rs8103142 TT; 74% vs. 67%, the rs12979860 C allele; and 67% vs. 64% the TCT haplotype with three favourable alleles. The adjusted Hazard Ratios (95% CI) for spontaneous clearance were: rs12979860: 3.80 (2.20, 6.54); rs8099917: 5.14 (2.46, 10.72); and rs8103142: 4.36 (2.49, 7.62). Even after adjusting for rs12979860, Aboriginals and females cleared HCV more often, HR (95% CI) = 1.53 (0.89, 2.61) and 1.42 (0.79, 2.53), respectively. Our results suggest that favourable IFNL3 genotypes are more common among Aboriginals than Caucasians, and may partly explain the higher HCV clearance rates seen among Aboriginals.

Treatment of chronic hepatitis C in a Canadian Aboriginal population: results from the PRAIRIE study

BACKGROUND

The Aboriginal population of Canada is at increased risk of exposure to the hepatitis C virus (HCV). Previous data indicate that spontaneous clearance of HCV occurs more often in Aboriginals than Caucasians. Whether this enhanced response extends to antiviral therapy for chronic HCV remains to be determined.

OBJECTIVES

To document and compare the biochemical and virological responses to antiviral therapy in HCV-infected Canadian Aboriginals and Caucasians.

METHODS

A total of 101 treatment-naive adult patients (46 Aboriginal, 55 Caucasian) with chronic HCV genotype 1 infections were prospectively treated with pegylated-interferon and ribavirin and followed as per national guidelines.

RESULTS

Aboriginals had higher HCV-RNA loads at baseline (6.42log(10) versus 5.98log(10); P<0.03). Although normalization of serum aminotransferase levels, decreases in viral loads, and rapid, early and end-of-treatment virological responses were similar in the two cohorts, sustained virological responses were significantly lower in Aboriginals (35% versus 55%; P=0.047). Premature discontinuation of treatment and⁄or loss of patients to follow-up was common (Aboriginals 37%, Caucasians 27%). Treatment-related side effects were similar in the two cohorts.

CONCLUSION

Despite higher rates of spontaneous HCV clearance, the response to antiviral therapy was similar, if not lower, in Aboriginals compared with Caucasians with chronic HCV genotype 1 infections. Compliance with treatment is an issue that needs to be addressed in the management of these patients.

The responses of Aboriginal Canadians to adjuvanted pandemic (H1N1) 2009 influenza vaccine

BACKGROUND

Because many Aboriginal Canadians had severe cases of pandemic (H1N1) 2009 influenza, they were given priority access to vaccine. However, it was not known if the single recommended dose would adequately protect people at high risk, prompting our study to assess responses to the vaccine among Aboriginal Canadians.

METHODS

We enrolled First Nations and Métis adults aged 20-59 years in our prospective cohort study. Participants were given one 0.5-mL dose of ASO3-adjuvanted pandemic (H1N1) 2009 vaccine (Arepanrix, GlaxoSmithKline Canada). Blood samples were taken at baseline and 21-28 days after vaccination. Paired sera were tested for hemagglutination-inhibiting antibodies at a reference laboratory. To assess vaccine safety, we monitored the injection site symptoms of each participant for seven days. We also monitored patients for general symptoms within 7 days of vaccination and any use of the health care system for 21-28 days after vaccination.

RESULTS

We enrolled 138 participants in the study (95 First Nations, 43 Métis), 137 of whom provided all safety data and 136 of whom provided both blood samples. First Nations and Métis participants had similar characteristics, including high rates of chronic health conditions (74.4%-76.8%). Pre-existing antibody to the virus was detected in 34.3% of the participants, all of whom boosted strongly with vaccination (seroprotection rate [titre ≥ 40] 100%, geometric mean titre 531-667). Participants with no pre-existing antibody also responded well. Fifty-eight of 59 (98.3%) First Nations participants showed seroprotection and a geometric mean titre of 353.6; all 30 Métis participants with no pre-existing antibody showed seroprotection and a geometric mean titre of 376.2. Pain at the injection site and general symptoms frequently occurred but were short-lived and generally not severe, although three participants (2.2%) sought medical attention for general symptoms.

INTERPRETATION

First Nations and Métis adults responded robustly to ASO3-adjuvanted pandemic (H1N1) 2009 vaccine. Virtually all participants showed protective titres, including those with chronic health conditions.

The potential influence of KIR cluster profiles on disease patterns of Canadian Aboriginals and other indigenous peoples of the Americas

Genetic differences in immune regulators influence disease resistance and susceptibility patterns. There are major health discrepancies in immune-mediated diseases between Caucasians and Canadian Aboriginal people, as well as with other indigenous people of the Americas. Environmental factors offer a limited explanation as Aboriginal people also demonstrate a rare resistance to chronic hepatitis C virus infection. Killer immunoglobulin-like receptors (KIRs) are known modulators of viral responses and autoimmune diseases. The possibility that variation in KIR cluster profiles contribute to the health outcomes of Aboriginal people was evaluated with Canadian Caucasian (n=93, population controls) and Aboriginal (n=86) individuals. Relative to Caucasians, the Aboriginal KIR cluster displayed a greater immune activating phenotype associated with genes of the B haplotype situated within the telomeric region. In conjunction, there was a decrease in the genes of the B haplotype from the centromeric region. Caucasian and Aboriginal cohorts further demonstrated distinct genotype and haplotype relationships enforcing the disconnect between the B haplotype centromeric and telomeric regions within the Aboriginal population. Moreover, Caucasian KIR cluster patterns reflected studies of Caucasians globally, as well as Asians. In contrast, the unique pattern of the Canadian Aboriginal cohort mirrored the phenotype of other indigenous peoples of the Americas, but not that of Caucasians or Asians. Taken together, these data suggest that historically indigenous peoples of the Americas were subject to immune selection processes that could be influencing the current disease resistance and susceptibility patterns of their descendents.

An Assessment of the Use of Chimpanzees in Hepatitis C Research Past, Present and Future: 2. Alternative Replacement Methods

The use of chimpanzees in hepatitis C virus (HCV) research was examined in the report associated with this paper ( 1: Validity of the Chimpanzee Model), in which it was concluded that claims of past necessity of chimpanzee use were exaggerated, and that claims of current and future indispensability were unjustifiable. Furthermore, given the serious scientific and ethical issues surrounding chimpanzee experimentation, it was proposed that it must now be considered redundant — particularly in light of the demonstrable contribution of alternative methods to past and current scientific progress, and the future promise that these methods hold. This paper builds on this evidence, by examining the development of alternative approaches to the investigation of HCV, and by reviewing examples of how these methods have contributed, and are continuing to contribute substantially, to progress in this field. It augments the argument against chimpanzee use by demonstrating the comprehensive nature of these methods and the valuable data they deliver. The entire life-cycle of HCV can now be investigated in a human (and much more relevant) context, without recourse to chimpanzee use. This also includes the testing of new therapies and vaccines. Consequently, there is no sound argument against the changes in public policy that propose a move away from chimpanzee use in US laboratories.