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

The Complex World of Kynurenic Acid: Reflections on Biological Issues and Therapeutic Strategy

It has been unequivocally established that kynurenic acid has a number of actions in a variety of cells and tissues, raising, in principle, the possibility of targeting its generation, metabolism or sites of action to manipulate those effects to a beneficial therapeutic end. However, many basic aspects of the biology of kynurenic acid remain unclear, potentially leading to some confusion and misinterpretations of data. They include questions of the source, generation, targets, enzyme expression, endogenous concentrations and sites of action. This essay is intended to raise and discuss many of these aspects as a source of reference for more balanced discussion. Those issues are followed by examples of situations in which modulating and correcting kynurenic acid production or activity could bring significant therapeutic benefit, including neurological and psychiatric conditions, inflammatory diseases and cell protection. More information is required to obtain a clear overall view of the pharmacological environment relevant to kynurenic acid, especially with respect to the active concentrations of kynurenine metabolites in vivo and changed levels in disease. The data and ideas presented here should permit a greater confidence in appreciating the sites of action and interaction of kynurenic acid under different local conditions and pathologies, enhancing our understanding of kynurenic acid itself and the many clinical conditions in which manipulating its pharmacology could be of clinical value.

Interferon-λ3 Gene Polymorphic Variants, rs4803217 and rs12980275, Responsiveness to HBV Vaccine and Outcome of HBV and HCV Exposure in Hemodialyzed Patients

Background: In non-uremic populations, rs4803217 in the IFNL3 messenger RNA 3’ untranslated region or rs12980275 downstream of IFNL3 is connected with the spontaneous or therapeutic clearance of HCV and HBV, and rs12980275 is correlated with plasma IFN-λ3 levels. Moreover, rs12980275 is associated with the sustained virological response following antiviral therapy of chronic hepatitis C in hemodialysis patients. Objectives: We investigated IFNL3 polymorphisms, rs4803217 and rs12980275, for association with responsiveness to HBV vaccine and natural consequences of HBV and HCV exposure among hemodialyzed individuals. Methods: The capacity to produce protective anti-HBs titers was recognized if they were ≥ 10 IU/L after vaccination or natural exposure. The IFNL3 rs4803217 (G>T) and rs12980275 (A>G) genetic variants were analyzed using a high-resolution melting curve method in 1,337 hemodialysis subjects. Plasma IFN-λ3 was determined in 188 individuals using ELISA. The Kaplan-Meier method was applied for the analysis of survival probability. Results: The tested polymorphisms did not show associations with the capacity to generate protective anti-HBs titers after HBV vaccination or exposition and self-limitation of HBV exposure. Natural HCV clearance was connected with the IFNL3 rs4803217 GG genotype (OR: 3.036, 95% CI: 1.544 - 5.969, P = 0.001) and haplotypes comprising at least two more frequent alleles but without any variant allele of IFNL3/IFNL4 genetic variants (P < 0.05). Plasma IFN-λ3 levels were not directly influenced by IFNL3 rs4803217 and rs12980275, but differed concerning HBV/HCV serum markers (P = 0.00005) and firmly correlated with anti-HBs titers (r = 0.537, P = 4.15E-16). Both tested polymorphisms were not significantly associated with the survival of hemodialysis patients. Conclusions: Genotyping IFNL3 rs4803217 may be advantageous in the prognosis of natural HCV clearance but does not predict the self-limitation of HBV exposure, responsiveness to HBV vaccine, or hemodialysis patients’ mortality.

Relative indoleamine 2,3-dioxygenase transcript level concerning anti-HBs titers in response to HBV vaccination in hemodialysis patients

BACKGROUND

Indoleamine 2,3-dioxygenase (IDO) is a negative regulator of the immune system. To approach reasons of variability in the generation of anti-HBs antibodies in response to HBV vaccination among hemodialysis (HD) subjects, we aimed to investigate whether the IDO gene (IDO1) transcript levels are associated with post-vaccination anti-HBs production and IDO1 polymorphic variants.

METHODS

The IDO1 transcript was determined by qRT-PCR analysis in 110 HD patients. IDO1 (rs3739319, rs9657182) genotyping was carried out by HRM analysis.

RESULTS

The relative IDO1 transcript levels were not associated with IDO1 polymorphic variants. There were 16 non-responders (not able to produce anti-HBs >10 IU/L), 74 patients with anti-HBs 10-999 IU/L, and 20 hyperactive responders (anti-HBs ≥1000 IU/L). IDO1 transcript levels were different among these groups (0.832, 0.423-4.373; 1.114, 0.317-6.582; 0.680, 0.164-3.014; respectively, Kruskal-Wallis P = 0.024). Significance in IDO1 transcript was shown between anti-HBs titers 10-999 IU/L and ≥1000 IU/L (P = 0.020). IDO1 transcript level <0.743 indicated 3.38 (1.17-9.72) higher probability of hyperactive immunization (adjusted P = 0.005).

CONCLUSION

In HD patients, ability to generate anti-HBs is not associated with IDO1 transcript levels. Hyperactive anti-HBs responses occur in patients showing lower IDO1 transcript. The latter cannot be predictable by genotyping IDO1 rs3739319 or rs9657182.