Association of vitamin D and polymorphisms of its receptor with antiviral therapy in pregnant women with hepatitis B.

Background: The interruption of mother-to-child transmission (MTCT) is considered important to decrease the individual and population morbidity of hepatitis B virus (HBV) infection as well as the global burden of hepatitis B. Serum vitamin D (VD) is associated with hepatitis B.

Aim: To assess whether baseline VD levels and single nucleotide polymorphisms of the VD receptor gene (VDR SNPs) are associated with the efficacy of tenofovir disoproxil fumarate (TDF) in the prevention of MTCT in pregnant women with high HBV viral loads.

Methods: Thirty-eight pregnant women who were at high risk for MTCT of HBV (those with an HBV DNA level ≥ 2 × 10 IU/mL during 12-24 wk of gestation) receiving antiviral therapy of TDF between June 1, 2019 and June 30, 2021 in Mianyang were included in this retrospective study. The women received 300 mg TDF once daily from gestational weeks 24-28 until 3 mo after delivery. To further characterize the clinical relevance of maternal serum HBV DNA levels, we stratified patients according to HBV DNA level as follows: Those with levels < 2 × 10 (full responder group) those levels ≥ 2 × 10 IU/mL (partial responder group) at delivery. Serum levels of 25-hydroxyvitamin D [25(OH)D], liver function markers, virological parameters, VDR SNPs and other clinical parameters were collected to analyze their association with the efficacy of TDF. The Mann-Whitney test or t test was used to analyze the serum levels of 25(OH)D in different groups. Multiple linear regressions were utilized to analyze the determinants of the maternal HBV DNA level at delivery. Univariate and multivariate logistic regression analyses were employed to explore the association of targeted antiviral effects with various characteristics at baseline and delivery.

Results: A total of 38 pregnant women in Mianyang City at high risk for MTCT of HBV were enrolled in the study. The MTCT rate was 0%. No mother achieved hepatitis B e antigen or hepatitis B surface antigen (HBsAg) clearance at delivery. Twenty-three (60.5%) participants were full responders, and 15 (39.5%) participants were partial responders according to antiviral efficacy. The present study showed that a high percentage (76.3%) of pregnant women with high HBV viral loads had deficient (< 20 ng/mL) or insufficient (≥ 20 but < 31 ng/mL) VD levels. Serum 25(OH)D levels in partial responders appeared to be significantly lower than those in full responders both at baseline (25.44 ± 9.42 17.66 ± 5.34 ng/mL, = 0.006) and delivery (26.76 ± 8.59 21.24 ± 6.88 ng/mL, = 0.044). Serum 25(OH)D levels were negatively correlated with maternal HBV DNA levels [log(10) IU/mL] at delivery after TDF therapy ( = -0.345, = 0.034). In a multiple linear regression analysis, maternal HBV DNA levels were associated with baseline maternal serum 25(OH)D levels ( < 0.0001, β = -0.446), BMI ( = 0.03, β = -0.245), baseline maternal log10 HBsAg levels ( = 0.05, β = 0.285) and cholesterol levels at delivery ( = 0.015, β = 0.341). Multivariate logistic regression analysis showed that baseline serum 25(OH)D levels (OR = 1.23, 95%CI: 1.04-1.44), maternal VDR Cdx2 TT (OR = 0.09, 95%CI: 0.01-0.88) and cholesterol levels at delivery (OR = 0.39, 95%CI: 0.17-0.87) were associated with targeted antiviral effects (maternal HBV DNA levels < 2 × 10 at delivery).

Conclusion: Maternal VD levels and VDR SNPs may be associated with the efficacy of antiviral therapy in pregnant women with high HBV viral loads. Future studies to evaluate the therapeutic value of VD and its analogs in reducing the MTCT of HBV may be justified.