Interactions between C-reactive protein genotypes with markers of nutritional status in relation to inflammation

Understanding and applying gene-environment interactions: a guide for nutrition professionals with an emphasis on integration in African research settings

Noncommunicable diseases (NCDs) are influenced by the interplay between genetics and environmental exposures, particularly diet. However, many healthcare professionals, including nutritionists and dietitians, have limited genetic background and, therefore, they may lack understanding of gene-environment interactions (GxEs) studies. Even researchers deeply involved in nutrition studies, but with a focus elsewhere, can struggle to interpret, evaluate, and conduct GxE studies. There is an urgent need to study African populations that bear a heavy burden of NCDs, demonstrate unique genetic variability, and have cultural practices resulting in distinctive environmental exposures compared with Europeans or Americans, who are studied more. Although diverse and rapidly changing environments, as well as the high genetic variability of Africans and difference in linkage disequilibrium (ie, certain gene variants are inherited together more often than expected by chance), provide unparalleled potential to investigate the omics fields, only a small percentage of studies come from Africa. Furthermore, research evidence lags behind the practices of companies offering genetic testing for personalized medicine and nutrition. We need to generate more evidence on GxEs that also considers continental African populations to be able to prevent unethical practices and enable tailored treatments. This review aims to introduce nutrition professionals to genetics terms and valid methods to investigate GxEs and their challenges, and proposes ways to improve quality and reproducibility. The review also provides insight into the potential contributions of nutrigenetics and nutrigenomics to the healthcare sphere, addresses direct-to-consumer genetic testing, and concludes by offering insights into the field's future, including advanced technologies like artificial intelligence and machine learning.

Relation of CRP gene variants to altered risk of Helicobacter pylori - associated chronic gastritis: A case-control study in Tunisia

BACKGROUND

We investigated the association between CRP variants and chronic gastritis in H. pylori-infected patients at the allele, genotype, and haplotype levels. This was also assessed according to serum hs-CRP levels.

METHODS

Study subjects consisted of 77 H. pylori-infected patients and 96 H. pylori-negative controls. Genotyping of the CRP rs1572970, rs876537, rs2794520, rs2808630, rs1130864, rs1417938, rs7553007, and rs4285692 variants were analyzed by real-time PCR.

RESULTS

Significantly higher MAF and increased risk of chronic gastritis were associated with rs1130864, rs1417938, and rs7553007, which persisted after controlling for key covariates. Significant differences in the genotype distribution of rs1130864, rs1417938, and rs7553007 were also seen between H. pylori-infected patients and healthy controls. Increased risk of H. pylori-associated chronic gastritis was associated with carriage of rs1130864 C/T, and more with T/T genotype carriers, as well as with rs1417938 T/A and A/A genotype carriers. Functionally, the distribution of rs1130864 and rs1417938 genotypes were significantly different between H. pylori-infected patients and controls in the low hs-CRP (<6 mg/L) group. CRP haplotype analysis identified Block 1 (rs1572970, rs876537, rs2794520), and Block 2 (rs2808630, rs1130864, rs1417938) associated with H. pylori infection. Haplotypes ACC (Block 1) and TTA and TTT (Block 2) were positively associated with H. pylori-associated chronic gastritis with low hs-CRP levels.

CONCLUSION

Altered serum levels of hs-CRP, stemming in part from the presence of specific genetic variants in CRP gene, modulate the risk of H. pylori infection.

Certain Associations Between Iron Biomarkers and Total and γ' Fibrinogen and Plasma Clot Properties Are Mediated by Fibrinogen Genotypes

Introduction: Evidence for the relationship between body iron and cardiovascular disease (CVD) is inconsistent and mechanisms involved remain poorly understood. Therefore, we first investigated whether there are linear or non-linear relationships between iron status and total and γ' fibrinogen as well as plasma fibrin clot properties and, second, determined whether there are interactions with iron biomarkers and fibrinogen and FXIII single nucleotide polymorphisms (SNPs) in relation to fibrinogen concentration and functionality. Methods: In this cross-sectional analysis of 2,010 apparently healthy Black South Africans we quantified total and γ' fibrinogen, serum iron, ferritin and transferrin using standardized methods and calculated transferrin saturation (TS). Clot architecture and lysis were explored with a global analytical turbidity assay. The SNPs were determined through an Illumina BeadXpress^® platform. Results: Total, but not %γ', fibrinogen negatively correlated with serum iron concentrations, although both decreased over iron tertiles. %γ' fibrinogen correlated negatively with transferrin and decreased over the transferrin tertiles. A weak negative association between total fibrinogen and TS was detected with fibrinogen decreasing over the TS tertiles and categories based on TS. Lag time correlated positively with transferrin and increased over transferrin tertiles, when adjusting for fibrinogen. Before adjusting for fibrinogen, lag time was shorter in those with adequate iron status based on TS than other iron subcategories. Clot lysis time (CLT) negatively correlated with ferritin and was longer in the first than in the third ferritin tertile. Among iron status categories based on ferritin, only CLT differed and was longer in those with adequate iron than with iron-overload. CLT negatively correlated with TS, albeit weakly, shortened over the TS tertiles and was shorter in those with adequate iron based on TS categories. Interactions were observed between FGB SNPs and some of the markers of iron status investigated, in relation to the clot properties with the most prominent associations detected in homozygous carriers of the variant alleles for whom increased iron status was more beneficial than for those harboring the wild-type alleles. Iron modulated the influence of the SNPs so that for the majority iron was beneficial in respect of clot properties, but even more so for a minority group harboring specific variant alleles. Conclusion: This is the first large-scale epidemiological study to relate fibrinogen concentration and functionality to markers of iron status and to take genetic factors into consideration. We have detected a relationship between iron biomarkers and fibrinogen as well as clot characteristics that are influenced by the genetic make-up of an individual.

Nutrigenomics of Dietary Lipids

Dietary lipids have a major role in nutrition, not only for their fuel value, but also as essential and bioactive nutrients. This narrative review aims to describe the current evidence on nutrigenomic effects of dietary lipids. Firstly, the different chemical and biological properties of fatty acids contained both in plant- and animal-based food are illustrated. A description of lipid bioavailability, bioaccessibility, and lipotoxicity is provided, together with an overview of the modulatory role of lipids as pro- or anti-inflammatory agents. Current findings concerning the metabolic impact of lipids on gene expression, epigenome, and gut microbiome in animal and human studies are summarized. Finally, the effect of the individual’s genetic make-up on lipid metabolism is described. The main goal is to provide an overview about the interaction between dietary lipids and the genome, by identifying and discussing recent scientific evidence, recognizing strengths and weaknesses, to address future investigations and fill the gaps in the current knowledge on metabolic impact of dietary fats on health.

Education, Smoking and CRP Genetics in Relation to C-Reactive Protein Concentrations in Black South Africans

Because elevated circulating C-reactive protein (CRP) and low socio-economic status (SES), have both been implicated in cardiovascular disease development, we investigated whether SES factors associate with and interact with CRP polymorphisms in relation to the phenotype. Included in the study were 1569 black South Africans for whom CRP concentrations, 12 CRP single nucleotide polymorphisms (SNPs), cardiovascular health markers, and SES factors were known. None of the investigated SES aspects was found to associate with CRP concentrations when measured individually; however, in adjusted analyses, attaining twelve or more years of formal education resulted in a hypothetically predicted 18.9% lower CRP concentration. We also present the first evidence that active smokers with a C-allele at rs3093068 are at an increased risk of presenting with elevated CRP concentrations. Apart from education level, most SES factors on their own are not associated with the elevated CRP phenotype observed in black South Africans. However, these factors may collectively with other environmental, genetic, and behavioral aspects such as smoking, contribute to the elevated inflammation levels observed in this population. The gene-smoking status interaction in relation to inflammation observed here is of interest and if replicated could be used in at-risk individuals to serve as an additional motivation to quit.

Interplay between the Mediterranean diet and C-reactive protein genetic polymorphisms towards inflammation in adolescents

AIM

From a nutrigenetics perspective, we aim to investigate the moderating role of the Mediterranean diet and each of its subgroups in the association between C-reactive protein (CRP) gene polymorphisms and CRP blood concentration in adolescents.

METHODS

In 562 adolescents (13-17 y) of the European HELENA study, data was available on circulating CRP levels as inflammatory biomarker, three CRP gene SNPs (rs3093068, rs1204, rs1130864), food intake determined by a self-administered computerized 24 h-dietary recall for 2 days, and body composition. A 9-point Mediterranean diet score and each food subgroup were tested as moderator via SNP*diet interaction. Analyzes were adjusted for age, sex, puberty, adiposity and socioeconomic status.

RESULTS

The minor allele frequencies of rs3093068 and rs1130864 SNPs (GG and TT, respectively) were associated with higher CRP concentrations, while rs1205 (CT/TT) was associated with lower CRP concentrations. There were significant interactions between rs3093068 and Mediterranean diet (B = -0.1139, p = 0.011), or the fish food subgroup (B = -0.0090, p = 0.022), so that those with the highest genetic CRP risk underwent the highest CRP attenuation by a healthier diet. Although the effect of diet and SNP was substantial, the explained variance by interaction was only 1%.

CONCLUSION

Greater adherence to the Mediterranean diet and particularly its fish component was associated with a lower CRP blood concentrations especially in those at highest genetic risk due to the rs3093068 SNP.

Nutritional genomics, inflammation and obesity

The Human Genome Project has significantly broadened our understanding of the molecular aspects regulating the homeostasis and the pathophysiology of different clinical conditions. Consequently, the field of nutrition has been strongly influenced by such improvements in knowledge - especially for determining how nutrients act at the molecular level in different conditions, such as obesity, type 2 diabetes, cardiovascular disease, and cancer. In this manner, characterizing how the genome influences the diet and vice-versa provides insights about the molecular mechanisms involved in chronic inflammation-related diseases. Therefore, the present review aims to discuss the potential application of Nutritional Genomics to modulate obesity-related inflammatory responses. Arch Endocrinol Metab. 2020;64(3):205-22.

CRP Genotypes Predict Increased Risk to Co-Present with Low Vitamin D and Elevated CRP in a Group of Healthy Black South African Women

Low 25-hydroxyvitamin D (25(OH)D) and elevated C-reactive protein (CRP) concentrations are independently associated with adverse health outcomes, including cardiovascular disease (CVD). Although an inverse association between these factors has been described, the underlying mechanisms remain unknown. We postulate that environment-gene interactions, through which 25(OH)D interacts with single nucleotide polymorphisms (SNPs) within the CRP gene, modulate CRP; that certain CRP genotypes predispose individuals to a co-phenotype of low 25(OH)D and elevated CRP concentrations; and that this co-phenotype is associated with higher CVD risk. Twelve CRP SNPs were genotyped, and both 25(OH)D and CRP were quantified, in 505 black South African women. Alarmingly, 66% and 60% of the women presented with deficient/insufficient 25(OH)D and elevated CRP concentrations, respectively. CRP concentrations were higher in individuals with lower 25(OH)D concentrations. However, no 25(OH)D-CRP genotype interactions were evident. Several genotypes were associated with an altered risk of presenting with the co-phenotype, indicating a genetic predisposition. Women presenting with this co-phenotype had higher blood pressure and increased anthropometric measures, which may predispose them to develop CVD. We recommend increasing vitamin D fortification and supplementation efforts to reduce inflammation among black women with vitamin D deficiency, thereby possibly curbing diseases contingent on the co-phenotype described here.

Interaction of SNP in the CRP gene and plasma fatty acid profile in inflammatory pattern: A cross-sectional population-based study

OBJECTIVE

To assess the interaction of three single nucleotide polymorphisms in the C-reactive protein (CRP) gene and plasma fatty acid (FA) levels in modulating inflammatory profile.

METHODS

A total of 262 subjects, aged >19 y and <60 y, participated in a cross-sectional, population-based study performed in Brazil. Three single nucleotide polymorphisms (rs1205, rs1417938, and rs2808630) spanning the CRP gene were genotyped. Eleven plasma inflammatory biomarkers and plasma FA profile were determined. Cluster analysis was performed to stratify individuals based on eleven inflammatory biomarkers into two groups: an inflammatory (INF) and a noninflammatory group.

RESULTS

The INF cluster had higher age, waist circumference, systolic blood pressure, and diastolic blood pressure; higher levels of triacylglycerol, high-sensitivity CRP, tumor necrosis factor-α, interleukin (IL)-8, IL-6, IL-1β, IL-12, IL-10, soluble monocyte chemoattractant protein-1, soluble intercellular adhesion molecule-1, C16:0, polyunsaturated fatty acid, and omega (n)-6 polyunsaturated fatty acid; and greater C20:4n-6, C18:1/18:0, and C20:4/20:3 ratios than the noninflammatory group. Statistically significant gene-plasma C16:1n-7 interaction was detected for rs1417938 (P = 0.047). Those with a dominant homozygous rs2808630 had a lower risk of belonging to the INF group with the upper 50th percentile of C20:4n-6, n-3 highly unsaturated FA, and C20:4/20:3 ratio. Regarding rs1205, A allele carriers had lower risk of being in the INF group when C20:5n-3 and n-3 highly unsaturated FA levels were greater than the median.

CONCLUSIONS

The INF group exhibited changes in metabolic parameters that predispose this group to chronic disease, where polymorphisms in the CRP gene modulated the risk of being in the INF group depending on individual plasma fatty acid and lipid profile.

C-reactive protein gene variants associated with recurrent pregnancy loss independent of CRP serum levels: a case-control study

The aim of this study is to investigate the association of recurrent pregnancy loss (RPL) with altered C-reactive protein (CRP) serum levels, and genetic variation in CRP gene. This was a retrospective case-control study, involving 275 women with three or more consecutive pregnancy losses, and 290 age-matched control women, who were recruited from outpatient obstetrics/gynecology clinics. CRP serum levels (hs-CRP) were determined by latex-enhanced nephelometry, and CRP genotyping was done by allelic discrimination. Mean serum CRP levels were higher in RPL cases than in control women, and carriage of the (minor) T allele of rs2794520 was associated with significant increase in CRP levels (P=0.017). Minor allele frequency (MAF) of rs7553007 was significantly different between RPL cases and control women, and was associated with reduced risk of RPL after adjusting for BMI and menarche. There was a significant enrichment of minor allele-carrying genotypes of rs1130864 and rs1417938 SNPs, and reduced frequency of minor allele-carrying genotypes of rs876537, rs2794520, and rs7553007 in RPL cases, thus assigning RPL-susceptible and -protective nature to these genotypes, respectively. Carriage of (minor) T allele of only rs2794520 was associated with significant increase in CRP levels. CRP variants that influenced circulating CRP levels in chronic inflammatory conditions are also associated with RPL, pointing to CRP as RPL candidate gene.