Comparative Analysis of Liver Injury-Associated Cytokines in Acute Hepatitis A and B

Sex differences in hepatitis A incidence rates-a multi-year pooled-analysis based on national data from nine high-income countries

BACKGROUND

Possible sex differences in hepatitis A virus (HAV) incidence rates in different age groups are not well documented. We aimed to obtain stable pooled estimates of such differences based on data from a number of high-income countries.

METHODS

We obtained data on incident cases of HAV by sex and age group over a period of 6-25 years from nine countries: Australia, Canada, Czech Republic, Finland, Germany, Israel, Netherland, New Zealand and Spain. Male to female incidence rate ratios (IRR) were computed for each year, by country and age group. For each age group, we used meta-analytic methods to combine the IRRs. Meta-regression was conducted to estimate the effects of age, country, and time period on the IRR.

RESULTS

A male excess in incidence rates was consistently observed in all age groups, although in the youngest and oldest age groups, where the numbers tended to be lower, the lower bounds of the 95% confidence intervals for the IRRs were less than one. In the age groups <1, 1-4, 5-9, 10-14, 15-44, 45-64 and 65+, the pooled IRRs (with 95% CI) over countries and time periods were 1.18 (0.94,1.48), 1.22 (1.16,1.29), 1.07 (1.03,1.11), 1.09 (1.04,1.14), 1.46 (1.30,1.64), 1.32 (1.15,1.51) and 1.10 (0.99,1.23) respectively.

CONCLUSIONS

The excess HAV incidence rates in young males, pooled over a number of countries, suggest that the sex differences are likely to be due at least in part to physiological and biological differences and not just behavioral factors. At older ages, differential exposure plays an important role. These findings, seen in the context of the excess incidence rates in young males for many other infectious diseases, can provide further keys to the mechanisms of the infection.

Distinct Cytokine Profiles Correlate with Disease Severity and Outcome in Longitudinal Studies of Acute Hepatitis B Virus and Hepatitis D Virus Infection in Chimpanzees

Historical studies conducted in chimpanzees gave us the opportunity to investigate the basis for the different severities of liver damage and disease outcome associated with infection with wild-type hepatitis B virus (HBV) versus a precore HBV mutant, HBV/hepatitis D virus (HDV) coinfection, and HDV superinfection. Weekly samples from 9 chimpanzees were studied for immune responses by measuring plasma levels of 29 cytokines in parallel with alanine aminotransferase (ALT) levels and viral kinetics. Comparison of classic acute hepatitis B (AHB) with severe or progressive AHB and HBV/HDV coinfection or superinfection identified distinct cytokine profiles. Classic AHB (mean ALT peak, 362 IU/liter) correlated with an early and significant induction of interferon alpha-2 (IFN-α2), IFN-γ, interleukin-12 p70 (IL-12 p70), and IL-17A. In contrast, these cytokines were virtually undetectable in severe AHB (mean ALT peak, 1,335 IU/liter), characterized by significant elevations of IL-10, tumor necrosis factor alpha (TNF-α), and MIP-1β. In progressive AHB (mean ALT peak, 166 IU/liter), there was a delayed and lower-magnitude induction of cytokines. The ALT peak was also delayed (mean, 23.5 weeks) compared to those of classic (13.5 weeks) and severe AHB (7.5 weeks). HBV/HDV coinfection correlated with significantly lower levels of IFN-α2, IFN-γ, and IL-17A, associated with the presence of multiple proinflammatory cytokines, including IL-1α, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-10, and IL-15. Conversely, HDV superinfection induced the highest ALT peak (1,910 IU/liter) and was associated with a general suppression of cytokines. Our data demonstrate that the most severe liver damage, caused by an HBV precore mutant and HDV, correlated with restricted cytokine expression and lack of Th1 response, raising the question of whether these viruses are directly cytopathic.IMPORTANCE Studies performed in chimpanzees at the National Institutes of Health (NIH) demonstrated a significant difference in ALT levels during acute hepatitis of different viral etiologies, with a hierarchy in the extent of liver damage according to the infecting virus: the highest level was in HDV superinfection, followed by infection with a precore HBV mutant, HBV/HDV coinfection, and, lastly, wild-type HBV infection. Our study demonstrates that both the virus and host are important in disease pathogenesis and offers new insights into their roles. We found that distinct cytokine profiles were associated with disease severity and clinical outcome. In particular, resolution of classic acute hepatitis B (AHB) correlated with a predominant Th1 response, whereas HBV/HDV coinfection showed a predominant proinflammatory response. Severe AHB and HDV superinfection showed a restricted cytokine profile and no evidence of Th1 response. The lack of cytokines associated with adaptive T-cell responses toward the precore HBV mutant and HDV superinfection argues in favor of a direct cytopathic effect of these viruses.

Natural History, Clinical Manifestations, and Pathogenesis of Hepatitis A

Hepatitis A virus (HAV) is transmitted by the fecal-oral route and is a major cause of acute viral hepatitis. The clinical manifestations of HAV infection range from asymptomatic infection to acute liver failure (ALF), but do not include progression to chronic hepatitis. Risk factors for severe acute hepatitis A are older age (>40 years) and preexisting liver disease. Some patients may show atypical clinical features such as relapsing hepatitis, prolonged cholestasis, or extrahepatic manifestations. Almost all hepatitis A patients spontaneously recover with supportive care. However, in the case of ALF (<1%), intensive care and urgent decision on liver transplantation are required. Liver injury during hepatitis A is not directly caused by HAV but is known to be caused by immune-mediated mechanisms. In this review, the natural history and clinical manifestations of hepatitis A are described. In addition, mechanisms of immunopathogenesis in hepatitis A are discussed.

CXCL10 is produced in hepatitis A virus-infected cells in an IRF3-dependent but IFN-independent manner

Acute hepatitis A caused by hepatitis A virus (HAV) infection is accompanied by severe liver injury in adult patients, and the liver injury is associated with the production of chemokines. Herein, we investigated the mechanism of how HAV infection induces the production of CXCR3 and CCR5 chemokines, such as CXCL10, CCL4 and CCL5. The production of CXCL10, CCL4 and CCL5 was markedly increased by HAV (HM-175/18f) infection in the culture of primary human hepatocytes and HepG2 cells. In particular, CXCL10 was produced in HAV-infected cells, not in neighboring uninfected cells. Moreover, these chemokines were significantly increased in the sera of acute hepatitis A patients. The production of IFN-λs was also robustly induced by HAV infection, and the blocking of secreted IFN-λs partially abrogated the production of CCL4 and CCL5 in HAV-infected cells. However, CXCL10 production was not decreased by the blocking of IFN-λs. Instead, CXCL10 production was reduced by silencing the expression of RIG-I-like receptor (RLR) signal molecules, such as mitochondrial antiviral signaling protein and interferon regulatory factor 3, in HAV-infected cells. In conclusion, HAV infection strongly induces the production of helper 1 T cell-associated chemokines, particularly CXCL10 via RLR signaling, even without secreted IFNs.

Slow reduction of IP-10 Levels predicts HBeAg seroconversion in chronic hepatitis B patients with 5 years of entecavir treatment

The aim of this study was to determine the correlation between dynamic changes in serum cytokine/chemokine expression levels in response to entecavir (ETV) treatment and HBV e antigen (HBeAg) seroconversion in patients with chronic hepatitis B (CHB). Four cytokines (interleukin [IL]-4, IL-6, IL-8, and interferon-γ) and five chemokines (macro-phage inflammatory protein [MIP]-1α, MIP-1β, platelet derived growth factor-BB, and interferon-inducible protein 10 [IP-10]) before ETV therapy and at 3, 6, 12, 24, 36 and 60 months during therapy in 105 CHB patients were analyzed. The results showed that the low decrease rate of IP-10 levels after 1 year of ETV treatment was an independent predictor of HBeAg seroconversion at year 5 (Hazard ratio = 0.972). The area under the receiver operating characteristic curves for the decrease rate of IP-10 levels after 1 year of treatment to discriminate a year-5 HBeAg seroconversion was 0.752 (p = 0.005). The results indicate that higher IP-10 level at year one of ETV treatment is associated with an increased probability of HBeAg seroconversion. Quantification of IP-10 during ETV treatment may help to predict long-term HBeAg seroconversion in patients with CHB.