Correlations of indoleamine 2,3-dioxygenase, interferon-λ3, and anti-HBs antibodies in hemodialysis patients

Background: Indoleamine 2,3-dioxygenase (IDO) contributes to maintaining immune homeostasis. Polymorphisms (SNPs) of the IDO encoding gene (IDO1) influence the IDO activity. Interferon (IFN)-λ3 induces IDO expression. We aimed to investigate whether IDO1 variants are associated with anti-HBs production in response to HBV vaccination or infection, interact with IFN-λ3 associated variants of IFNL4, and influence survival of hemodialysis (HD) patients. We also tested circulating IDO concerning IDO1 SNPs and plasma IFN-λ3 and anti-HBs levels.

Methods: The study included HD patients who had established status concerning responsiveness to HBV vaccination (n = 1022) or were exposed to HBV (n = 315). Ability to generate anti-HBs was diagnosed if anti-HBs after vaccination or infection exceeded 10 IU/L. Genotyping of IDO1 (rs3739319 A < G, rs9657182 C < T), IFNL4 rs8099917 G < T and IFNL4 rs12979860 C > T polymorphisms was carried out by high-resolution melting curve analysis. Circulating IDO and IFN-λ3 were measured with ELISA in 57 subjects. Survival probability was analyzed using the Kaplan-Meier method.

Results: IDO1 SNPs did not correlate with the ability to produce anti-HBs after vaccination or infection. Anti-HBs titers, including a frequency of anti-HBs ≥ 1000 IU/l, also did not associate with IDO1 SNPs, but there was an epistatic interaction between rs9657182, rs8099917, and rs12979860 concerning anti-HBs titers (P = 0.028). Significant associations between IDO1 SNPs and circulating IDO were not demonstrated. Anti-HBs titers negatively correlated with plasma IDO (r = -0.358, P = 0.006), and positively with circulating IFN-λ3 (r = 0.498, P = 0.00008). IDO and IFN-λ3 did not correlate. Patients possessing the rs9657182 TT genotype showed higher infection-related mortality, also in multivariate analysis (HR 2.073, 1.221-3.518, P = 0.007).

Conclusions: IDO1 rs9657182, IFNL4 rs8099917, and IFNL4 rs12979860 show epistatic interaction concerning anti-HBs titers. Overreacting immune responses to HBsAg occur in patients with lower IDO but simultaneously higher IFN-λ3 levels. The rs9657182 TT genotype associates with infection-related mortality of HD patients.