Evidence of rotavirus vaccine impact in sub-Saharan Africa: Systematic review and meta-analysis.

BACKGROUND: Over 34 countries in Africa have introduced rotavirus vaccine to their national immunization programs: monovalent (Rotarix®, RV1) and pentavalent (RotaTeq®, RV5) after South Africa introduced it in 2009. Since then several studies assessing the impact of the vaccine have been conducted. The principal aim of this study was to evaluate the impact of rotavirus vaccine in sub-Saharan Africa. METHODS: A Literature search was performed using Mendeley, PubMed, ScienceDirect, grey literature and Web of Science databases of published studies from January 1, 2017, as years of recent publications on rotavirus vaccine impact in sub-Saharan Africa. A meta-analysis was conducted for rotavirus infection in children under 5 years using proportions of pre and post-vaccine introduction in these populations. Random-effect estimates were considered since the samples were from universal populations. RESULTS: Out of the 935 articles identified, 17 studies met the inclusion for systematic review and meta-analysis. The pooled proportion for pre-vaccination period was 42%, 95% (CI: 38-46%), and reduced to 21%, 95% (CI: 17-25%) during post-vaccination period. Rotavirus diarrhea significantly reduced in children < 12 months as compared to children 12-24 months old. Seasonal peaks of rotavirus diarrhea were between June-September. However, data is limited to one year of post-vaccine introduction, and bias may present due to early vaccine impact. CONCLUSION: We observed that the introduction of the rotavirus vaccine was partly responsible for the significant reduction in the burden of rotavirus-associated diarrhea in sub-Saharan Africa. Therefore, there is a need to encourage the remaining countries to introduce the vaccine to their routine national immunization programs.

Association of genetic and epigenetic variants in one-carbon metabolism gene with folate treatment response in hyperhomocysteinaemia.

BACKGROUND: Folate supplementation treatment is the first-line therapy in hyperhomocysteinaemia (HHcy). Up to 40% of HHcy patients do not benefit from folate therapy. Genetic and epigenetic factors of one-carbon metabolism (1-CM) might be identified as a predictor of folate supplementation treatment response. In the present study, we attempt to identify whether genetic and epigenetic factors might predict folate treatment response. METHODS: A total of 230 patients with HHcy were involved in this prospective cohort study. Differences between baseline concentrations and concentrations obtained at 90 days of treatment were calculated to evaluate the treatment response. General linear models and Pearson correlation was used to explore associations among single-nucleotide polymorphisms (SNPs), DNA methylation, and folate treatment response. Finally, mediation analysis was performed to investigate whether DNA methylation of MTRR mediates the association between SNPs and treatment response. RESULTS: MTHFD rs1950902 and MTRR rs162036, rs1801394 was associated with the folate treatment response (P = 0.000, 0.048, and 0.043, respectively). CBS and CBS_2 DNA methylation was significantly associated with folate treatment response (P = 0.0009 and < 0.001). DNA methylation of MTHFR, MTR, and MTRR was also significantly associated with folate treatment response (P < 0.001). DNA methylation of MTRR and MTRR_1 mediated 40.71% and 40.47% of the effect of rs1801394 on folate treatment response, respectively. CONCLUSIONS: Our results indicated that the 1-CM gene SNPs and DNA methylation was associated with folate treatment response and can be further evaluated relationship between SNPs and DNA methylation in 1-CM with treatment response in a larger sample.

Associations of MTRR A66G polymorphism and promoter methylation with ischemic stroke in patients with hyperhomocysteinemia.

BACKGROUND: Patients with hyperhomocysteinemia (HHcy) have a higher risk of developing ischemic stroke (IS). The association between MTRR A66G polymorphism and promoter methylation with IS in patients with HHcy is also uncertain. The present study aimed to investigate the association between the MTRR polymorphism and methylation with IS in HHcy patients. METHODS: This case-control study included a total of 304 HHcy patients (95 with IS and 209 without IS). Multivariate logistic regression analyses were applied to explore the association between MTRR polymorphism and classical atherothrombotic risk factors with the risk of IS. RESULTS: The log-additive and dominant models were markedly different in participants with IS compared to the control group (p = 0.031 and 0.016, respectively). The log-additive and dominant showed a significant association with IS in the low level plasma homocysteine groups (p = 0.024 and 0.014, respectively). No significant difference of methylation between IS and without IS group (p > 0.05). Patients with high plasma homocysteine had a 4.041-4.941 fold higher risk of IS (p = 0.01, 0.016 and 0.041, respectively) compared to the low plasma homocysteine group. Age, diabetes, hypertension and plasma homocysteine were the risk factors for IS in patients with HHcy (p = 0.033, 0.000, 0.001 and 0.038, respectively). CONCLUSIONS: MTRR A66G polymorphism and an elevated plasma plasma homocysteine level were significantly associated with an increased risk of IS in patients with HHcy. Age, diabetes, hypertension and Hcy were all found to be associated with IS.

CBS gene polymorphism and promoter methylation-mediating effects on the efficacy of folate therapy in patients with hyperhomocysteinemia.

BACKGROUND: A decrease in cystathionine beta-synthase (CBS) enzyme activity could lead to hyperhomocysteinemia (HHcy). Studies have revealed that DNA methylation has a mediating effect on the development of diseases. The present study aimed to explore CBS promoter methylation-mediating effects on the efficacy of folate treatment for HHcy. METHODS: HHcy patients were treated with folate (5 mg/day) for 90 days and then divided into a failure group (Hcy ≥ 15 µmol/l) and a success group (Hcy < 15 µmol/l) according to post-treatment plasma Hcy levels. Genotyping of CBS gene (rs2851391 and rs706209) in patients (n = 638) was detected using a MassArray system (Sequenom, San Diego, CA, USA). The baseline DNA methylation levels of patients (n = 299) were detected using MethylTarget™ technology (Genesky Biotechnologies Inc., Shanghai, China). RESULTS: The CBS rs2851391 TC + CC genotype was related to a 57% reduction of failure risk in HHcy treatment compared to the TT genotype (95% confidence interval [CI] = 0.19-0.97). The CBS rs706209 CT + TT genotype had a 2.97-fold increased risk of failure to treatment compared to the CC genotype (95% CI = 1.52-5.80). After adjustment for confounding factors, the odds ratio (95% CI) for the risk of failure in HHcy treatment in total and male patients was 0.55 (0.32-0.93) and 0.34 (0.16-0.69), respectively, for patients with higher methylation levels (≥ methylation median). Additionally, baseline CBS promoter methylation mediated 33.39% of the effect of rs2851391 on the efficacy of folate treatment for HHcy (ACME [average causal mediation effects]: -0.05, 95% CI = -0.11 to 0.00, p = 0.046). CONCLUSIONS: The present study indicates that CBS gene polymorphism and promoter methylation could affect the efficacy of HHcy. There were potentially causal effects of genetic, epigenetic variations at the CBS rs2851391 locus on the efficacy of HHcy therapy with folate.

Genetic and epigenetic regulation of BHMT is associated with folate therapy efficacy in hyperhomocysteinaemia.

BACKGROUND AND OBJECTIVES: Hyperhomocysteinaemia (HHcy) is an independent risk factors for several disorders, including cardiovascular disease. The understanding of the relationship among genetic, epigenetic and the efficacy of folate therapy for HHcy remain unclear. This study aim to investigate whether betaine-homocysteine methyltransferase (BHMT) single-nucleotide polymorphisms (SNPs) and DNA methylation are related to the efficacy of folate therapy for HHcy and whether BHMT DNA methylation mediates the SNP-folate therapy efficacy association. METHODS AND STUDY DESIGN: A total of 638 patients with HHcy were involved in this prospective cohort study. Logistic and linear regression was used to explore associations among SNPs, DNA methylation, and folate therapy efficacy. Finally, mediation analysis was performed to investigate whether DNA methylation of BHMT mediates the association between SNPs and folate therapy efficacy. RESULTS: BHMT rs3733890 was significantly associated with folate therapy efficacy (p<0.05). BHMT and BHMT_1 DNA methylation level was significantly associated with folate therapy efficacy (p=0.017 and p=0.028). DNA methylation of BHMT and BHMT_1 mediated 34.84% and 33.06% of the effect of rs3733890 on folate therapy efficacy, respectively. CONCLUSIONS: There has a consistent interrelationship among BHMT genetic variants, methylation levels of BHMT, and folate therapy efficacy. BHMT and BHMT_1 DNA methylation proportionally mediated the effects of rs3733890 SNPs on the efficacy of folate therapy for HHcy.

Association between BHMT and CBS gene promoter methylation with the efficacy of folic acid therapy in patients with hyperhomocysteinemia.

Both betaine homocysteine methyltransferase (BHMT) and cystathionine ß-synthase (CBS) are major enzymes in the metabolism of plasma homocysteine (Hcy). Abnormal methylation levels of BHMT and CBS are positively associated with Hcy levels. The present study is performed to explore the association between the methylation levels in the promoter regions of the BHMT and CBS genes and the efficacy of folic acid therapy in patient with hyperhomocysteinemia (HHcy). A prospective cohort study recruiting HHcy (Hcy ≥ 15 µmol/L) patients was performed. The subjects were treated with oral folic acid (5 mg/d) for 90 days, and the patients were divided into the success group (Hcy < 15 µmol/L) and the failure group (Hcy ≥ 15 µmol/L) according to their Hcy levels after treatment. In the logistic regression model with adjusted covariates, the patients with lower total methylation levels in the BHMT and CBS promoter regions exhibited 1.627-fold and 1.671-fold increased risk of treatment failure compared with higher methylation individuals, respectively. Similarly, subjects who had lower methylation levels (