The G protein beta3 subunit 825T allele is a genetic marker for enhanced T cell response

Gestational Weight Gain: Is the Role of Genetic Variants a Determinant? A Review

Excessive or insufficient gestational weight gain (GWG) leads to diverse adverse maternal and neonatal outcomes. There is evidence that pregestational body mass index (pBMI) plays a role in GWG, but no genetic cause has been identified. In this review, we aim to analyze genotype variants associated with GWG. Results: We identified seven genotype variants that may be involved in GWG regulation that were analyzed in studies carried out in Brazil, Romania, the USA, Turkey, Ukraine, and Canada. Some genetic variants were only associated with GWG in certain races or depending on the pBMI. In women who were obese or overweight before gestation, some genetic variants were associated with GWG. Environmental and genetic factors together showed a greater association with GWG than genetic factors alone; for example, type of diet was observed to have a significant influence. Conclusions: We found little scientific evidence of an association between genotype variants in countries with a high prevalence of women of reproductive age who are overweight and obese, such as in Latin America. GWG may be more dependent on environmental factors than genetic variants. We suggest a deeper study of genetic variants, cytokines, and their possible association with GWG, always with the respective control of potential cofounding factors, such as pBMI, diet, and race.

Lymphocyte Function at Baseline Could Be a New Predictor of Tumor Burden following Six Cycles of Radium-223 Therapy in Patients with Metastasized, Castration-Resistant Prostate Cancer

Previous data indicate that one cycle of treatment with radium-223 (223Ra) did not significantly impair lymphocyte function in patients with metastasized, castration-resistant prostate cancer. The aim of the current study was to assess in 21 patients whether six cycles of this therapy had an effect on lymphocyte proliferation and interferon-γ and interleukin (IL)-10 ELISpot results. Lymphocyte proliferation after stimulation with microbial antigens and the production of interferon-γ continuously decreased after six cycles of radionuclide therapy, reaching statistical significance (p < 0.05) at months 1, 2, 4, and/or 6 after therapy. One month after the last cycle of therapy, 67% of patients showed a decrease in tumor burden. The tumor burden correlated negatively with IL-10 secretion at baseline, e.g., after stimulation with tetanus antigen (p < 0.0001, r = -0.82). As determined by receiver operating characteristic (ROC) curve analysis, tetanus-specific IL-10 spots at baseline had the highest predictive value (p = 0.005) for tumor burden at month 6, with an area under the curve (AUC) of 0.90 (sensitivity 100%, specificity 78%). In conclusion, we observed an additive effect of treatment with 223Ra on immune function and found that IL-10 secretion at baseline predicted tumor burden at month 6 after treatment.

Association of GNB3, ACE polymorphisms with POAG and NTG

PURPOSE

Primary open-angle glaucoma (POAG) represents the most prevalent form of glaucoma and stands as a foremost contributor to irreversible vision impairment on a global scale. Despite notable strides made in comprehending the genetic underpinnings of POAG, investigations within the context of Russia remain constrained.

METHODS

The study cohort comprised a total of 235 individuals, with 135 of them exhibiting various forms of glaucoma encompassing both POAG and (NTG, while the remaining 100 individuals served as control subjects. Each participant underwent a comprehensive ocular examination to ascertain their ocular health status. Genotyping of the relevant single nucleotide polymorphisms (SNPs) was carried out using the Taq Man genotyping assay. Specifically, the two SNPs under scrutiny were GNB3 rs5443 gene and ACE rs4646994. Statistical analysis was performed to evaluate the association of these SNPs with glaucoma risk.

RESULTS

The presence of the T allele of rs5443 was found to be associated with NTG (p = .004). However, no statistically significant correlation was identified between this SNP and POAG (p = .88).

CONCLUSION

This study provides evidence of an association between the T allele of rs5443 and a reduced susceptibility NTG within the Russian population. These observations augment the comprehension of the genetic underpinnings of glaucoma and hold potential implications for the prospective development of targeted therapeutic interventions.

Spotlight on contributory role of host immunogenetic profiling in SARS-CoV-2 infection: Susceptibility, severity, mortality, and vaccine effectiveness

BACKGROUND

The SARS-CoV-2 virus has spread continuously worldwide, characterized by various clinical symptoms. The immune system responds to SARS-CoV-2 infection by producing Abs and secreting cytokines. Recently, numerous studies have highlighted that immunogenetic factors perform a putative role in COVID-19 pathogenesis and implicate vaccination effectiveness.

AIM

This review summarizes the relevant articles and evaluates the significance of mutation and polymorphism in immune-related genes regarding susceptibility, severity, mortality, and vaccination effectiveness of COVID-19. Furthermore, the correlation between host immunogenetic and SARS-CoV-2 reinfection is discussed.

METHOD

A comprehensive search was conducted to identify relevant articles using five databases until January 2023, which resulted in 105 total articles.

KEY FINDINGS

Taken to gather this review summarized that: (a) there is a plausible correlation between immune-related genes and COVID-19 outcomes, (b) the HLAs, cytokines, chemokines, and other immune-related genes expression profiles can be a prognostic factor in COVID-19-infected patients, and (c) polymorphisms in immune-related genes have been associated with the effectiveness of vaccination.

SIGNIFICANCE

Regarding the importance of mutation and polymorphisms in immune-related genes in COVID-19 outcomes, modulating candidate genes is expected to help clinical decisions, patient outcomes management, and innovative therapeutic approach development. In addition, the manipulation of host immunogenetics is hypothesized to induce more robust cellular and humoral immune responses, effectively increase the efficacy of vaccines, and subsequently reduce the incidence rates of reinfection-associated COVID-19.

Potassium channel-related genes are a novel prognostic signature for the tumor microenvironment of renal clear cell carcinoma

Clear cell renal cell carcinoma (ccRCC) accounts for 80% of renal cell carcinomas (RCCs), and its morbidity and prognosis are unfavorable. Surgical resection is the first-line treatment for ccRCC, but the oncogenesis of ccRCC is very complex. With the development of high-throughput sequencing technology, it is necessary to analyze the transcriptome to determine more effective treatment methods. The tumor microenvironment (TME) is composed of tumor cells, various immune-infiltrating cells, fibroblasts, many cytokines, and catalysts. It is a complex system with a dynamic balance that plays an essential role in tumor growth, invasion, and metastasis. Previous studies have confirmed that potassium channels can affect the immune system, especially T lymphocytes that require potassium channel activation. However, the effect of potassium channels on the TME of ccRCC remains to be studied. Therefore, this study aims to construct a prognostic signature for ccRCC patients based on potassium ion channel-related genes (PCRGs), assess patient risk scores, and divide patients into high- and low-risk groups based on the cutoff value. In addition, we investigated whether there were differences in immune cell infiltration, immune activator expression, somatic mutations, and chemotherapeutic responses between the high- and low-risk groups. Our results demonstrate that the PCRG signature can accurately assess patient prognosis and the tumor microenvironment and predict chemotherapeutic responses. In summary, the PCRG signature could serve as an auxiliary tool for the precision treatment of ccRCC.

GNB3 c.825c>T polymorphism influences T-cell but not antibody response following vaccination with the mRNA-1273 vaccine

Background: Immune responses following vaccination against COVID-19 with different vaccines and the waning of immunity vary within the population. Genetic host factors are likely to contribute to this variability. However, to the best of our knowledge, no study on G protein polymorphisms and vaccination responses against COVID-19 has been published so far.

Methods: Antibodies against the SARS-CoV-2 spike protein and T-cell responses against a peptide pool of SARS-CoV-2 S1 proteins were measured 1 and 6 months after the second vaccination with mRNA-1273 in the main study group of 204 participants. Additionally, antibodies against the SARS-CoV-2 spike protein were measured in a group of 597 participants 1 month after the second vaccination with mRNA-1273. Genotypes of GNB3 c.825C>T were determined in all participants.

Results: The median antibody titer against the SARS-CoV-2 spike protein and median values of spots increment in the SARS-CoV-2 IFN-γ ELISpot assay against the S1-peptide pool were significantly decreased from months 1 to 6 (p < 0.0001). Genotypes of GNB3 c.825C>T had no influence on the humoral immune response. At month 1, CC genotype carriers had significantly increased T-cell responses compared to CT (p = 0.005) or TT (p = 0.02) genotypes. CC genotype carriers had an almost 6-fold increased probability compared to TT genotype carriers and an almost 3-fold increased probability compared to T-allele carriers to mount a SARS-CoV-2-specific T-cell response above the median value.

Conclusion: CC genotype carriers of the GNB3 c.825C>T polymorphism have an increased T-cell immune response to SARS-CoV-2, which may indicate better T-cell-mediated protection against COVID-19 after vaccination with mRNA-1273.

GNB3 c.825C>T (rs5443) Polymorphism and Risk of Acute Cardiovascular Events after Renal Allograft Transplant

The c.825C>T single-nucleotide polymorphism (rs5443) of the guanine nucleotide-binding protein subunit β3 (GNB3) results in increased intracellular signal transduction via G-proteins. The present study investigated the effect of the GNB3 c.825C>T polymorphism on cardiovascular events among renal allograft recipients posttransplant. Our retrospective study involved 436 renal allograft recipients who were followed up for up to 8 years after transplant. The GNB3 c.825C>T polymorphism was detected with restriction fragment length polymorphism (RFLP) polymerase chain reaction (PCR). The GNB3 TT genotype was detected in 43 (10%) of 436 recipients. Death due to an acute cardiovascular event occurred more frequently among recipients with the TT genotype (4 [9%]) than among those with the CC/CT genotypes (7 [2%]; p = 0.003). The rates of myocardial infarction (MI)−free survival (p = 0.003) and acute peripheral artery occlusive disease (PAOD)−free survival (p = 0.004) were significantly lower among T-homozygous patients. A multivariate analysis showed that homozygous GNB3 c.825C>T polymorphism exerted only a mild effect for the occurrence of myocardial infarction (relative risk, 2.2; p = 0.065) or acute PAOD (relative risk, 2.4; p = 0.05) after renal transplant. Our results suggest that the homozygous GNB3 T allele exerts noticeable effects on the risk of MI and acute PAOD only in the presence of additional nonheritable risk factors.

The GNB3 c.825C>T (rs5443) polymorphism and protection against fatal outcome of corona virus disease 2019 (COVID-19)

Background and aims: Albeit several factors which influence the outcome of corona virus disease (COVID-19) are already known, genetic markers which may predict the outcome of the disease in hospitalized patients are still very sparse. Thus, in this study, we aimed to analyze whether the single-nucleotide polymorphism (SNP) rs5443 in the gene GNB3, which was associated with higher T cell responses in previous studies, might be a suitable biomarker to predict T cell responses and the outcome of COVID-19 in a comprehensive German cohort.

Methods: We analyzed the influence of demographics, pre-existing disorders, laboratory parameters at the time of hospitalization, and GNB3 rs5443 genotype in a comprehensive cohort (N = 1570) on the outcome of COVID-19. In a sub cohort, we analyzed SARS-CoV-2-specific T cell responses and associated GNB3 rs5443 genotypes. We investigated the influence of all factors on COVID-19 fatality in multivariable analysis.

Results: We found a younger patient age, normotension or absence of diabetes mellitus or cardiovascular diseases, normal blood cell counts, and low inflammatory markers at hospital admission were protective factors against fatal course of disease. In addition, the rs5443 TT genotype was significantly associated with protection against COVID-19 fatality (OR: 0.60, 95% CI: 0.40–0.92, p = 0.02). We also observed significantly increased SARS-CoV-2-specific T cell responses in rs5443 TT genotype carriers (p = 0.01). Although we observed a significant association of the factors described previously in univariate analysis, only a younger age of the patients, normal blood cell counts, and the GNB3 rs5443 TT genotype remained independent predictors against COVID-19 fatality in multivariable analysis.

Conclusion: Immutable predictors for COVID-19 fatality are relatively rare. In this study we could show that the TT genotype of the SNP rs5443 in the gene GNB3 is associated with protection against COVID-19 fatality. It was as well correlated to higher SARS-CoV-2-specific T cell responses, which could result in a milder course of disease in those patients. Based on those observations we hereby provide a further prognostic biomarker, which might be used in routine diagnostics as a predictive factor for COVID-19 mortality already upon hospitalization.

Vof16-miR-205-Gnb3 axis regulates hippocampal neuron functions in cognitively impaired diabetic rats

Background

Diabetes is a chronic metabolic disease and an independent risk factor for cognitive damage. Non-protein coding RNAs, including long non-coding RNAs (lncRNAs) and microRNAs (miRNAs), are involved in various pathophysiological conditions.

Methods

In this study, cognitive impairment was induced in diabetics rats by streptozotocin (STZ) injection, and the differential lncRNAs and mRNAs in rat hippocampal tissue between control and STZ-treated groups were analyzed with microarray.

Results

In the hippocampus of STZ-treated diabetic rats, lncRNA Vof-16, and Gnb3 mRNA were significantly upregulated and silicon analysis showed that Vof-16 and miR-205 share the same miRNA response element (MRE). In addition, the overexpression of Vof-16 in primary hippocampal neurons inhibited the expression of miR-205, and vice versa. Dual luciferase assay verified the binding between Vof-16 and miR-205, and Vof-16 was seen to promote the proliferation of primary hippocampal neurons via sponging miR-205. Silicon analysis predicted that miR-205 could bind with Gnb3, which was verified with dual luciferase assay, and the overexpression of miR-205 could inhibit the protein level of Gnb3, which could be rescued by co-expression with Vof-16. In conclusion, lncRNA Vof-16 regulated Gnb3 expression by competitively binding to miR-205.

Conclusions

These results provided a novel regulation axis for the pathogenesis of STZ-induced diabetes.

Gene Polymorphisms and Susceptibility to Functional Dyspepsia: A Systematic Review and Meta-Analysis

Functional dyspepsia (FD) is a common chronic gastrointestinal disorder with a complex, undefined mechanism. Clustering of patients with FD in families highlights the role of genetic factors in the pathogenesis of FD. We performed a systematic review and meta-analysis to clarify the associations between specific gene polymorphisms and FD susceptibility. PubMed, EMBASE, the Cochrane Library, and HuGE database were searched. An additive model was adopted to determine whether previous studied genes are associated with FD susceptibility. Carriers of minor allele in GNB3 825C>T (OR = 1.15, 95% CI 0.99-1.34, P = 0.07), SCL6A4 5HTTLPR (OR = 0.92, 95% CI 0.75-1.12, P = 0.40), and CCK-1R 779T>C (OR = 0.86, 95% CI 0.72-1.03, P = 0.09) genes failed to demonstrate susceptibility to FD. In a subgroup analysis, only minor allele (T) in GNB3 825C>T was associated with an increased susceptibility to the epigastric pain syndrome subtype (OR = 1.34, 95% CI 1.10-1.63, P = 0.003). Our meta-analysis based on available studies using an additive model failed to show that GNB3, SCL6A4, and CCK-1R polymorphisms are associated with FD susceptibility.

Immunopathological and molecular basis of functional dyspepsia and current therapeutic approaches

INTRODUCTION

Functional dyspepsia (FD) is widespread with 20% prevalence worldwide and a significant economic burden due to health care cost and constraints on daily activities of patients. Despite extensive investigation, the underlying causes of dyspepsia in a majority of patients remain unknown. Common complaints include abdominal discomfort, pain, burning, nausea, early satiety, and bloating. Motor dysfunction of the gut was long considered a major cause, but recent investigations suggest immune-based pathophysiological and molecular events in the duodenum are more probable contributing factors. Areas Covered: Inflammatory mediators and immune cells including duodenal eosinophils, intraepithelial lymphocytes, and T-cells have been implicated in the underlying cause of disease process, as have genetic factors. In this article, we critically reviewed findings, identified gaps in knowledge and suggested future directions for further investigation to identify targets and develop better therapeutic approaches. Expert commentary: Impaired gastric accommodation, slow gastric emptying, and increased visceral sensitivity have long been thought of as main causal factors of FD. However, more recent identification of eosinophilic degranulation and recruitment of T cells that induce mild duodenal inflammation are giving rise to new insights into immune-mediated pathophysiology. These insights offer promising avenues to explore for immune-mediated therapy in the future.

Lymphocyte function following radioiodine therapy in patients with thyroid carcinoma

Aim: Since the nuclear disaster in Fukushima has raised great concern about the danger of radioactivity, we here addressed the question if the therapeutic use of iodine 131, the most frequently applied radionuclide, was harmful to immune function in patients. It was our aim to define for the first time in a clinical setting how radioiodine therapy alters anti-microbial immune responses. Patients, methods: In 21 patients with thyroid carcinoma anti-microbial lymphocyte responses were assessed by lymphocyte transformation test and ELISpot – measuring lymphocyte proliferation and on a single cell level production of pro- and anti-inflammatory cytokines (interferon-γ and interleukin- 10) – prior to therapy, at day 1 and day 7 post therapy. Results: Proliferative lymphocyte responses and interferon-γ production after in vitro stimulation with microbial antigens were significantly (p < 0.05) increased at day 1 vs. pre therapy, and returned to pre therapy levels at day 7. On the contrary, at day 1 interleukin-10 production was significantly (p < 0.05) reduced. Thus, we observed a short-term increase in pro-inflammatory immune responses. However, T lymphocyte responses were in the range of healthy controls at all three time points. Conclusion: Thyroid carcinoma patients receiving radioiodine therapy do not display any sign of immunosuppression.

Viral and host factors associated with outcomes of hepatitis C virus infection (Review)

Hepatitis C virus (HCV) infection is a major health issue globally. Owing to the progress made in host genetics and HCV molecular virology, emerging data have suggested that the natural course and treatment response in patients with HCV infection are largely determined by complex host‑viral interactions. HCV genotype is the most important viral factor predicting the response to pegylated interferon‑α plus ribavirin therapy. The subtype of HCV genotype 1 is the key viral factor that predicts the efficacy of direct‑acting antiviral therapy. HCV genome heterogeneity and baseline viral load are additionally associated with the treatment response. Multiple host genetic variants localized in genes associated with the immune response have been identified as predictors of spontaneous disease course and therapy outcome in chronic HCV. However, most findings from candidate gene association studies have not been proven universal for all investigated populations and independent studies. Previous findings in independent large genome wide association studies confirmed that interferon‑λ3 gene polymorphisms are associated with spontaneous clearance and treatment responsiveness. A polymorphism of the inosine triphosphatase gene has been identified as a protective factor against ribavirin‑induced anemia and dose reductions. Another genetic variant in the patatin‑like phospholipase domain containing 3 genes is associated with hepatic steatosis and fibrosis in patients with HCV. The present review focused on the identified viral and host factors associated with outcomes of patients with HCV, and assessed the involvement of viral and host genetics in the natural history and treatment outcomes of HCV infection. This will provide novel ideas concerning personalized prevention and individualized clinical management.

Estimation of the relationship between the polymorphisms of selected genes: ACE, AGTR1, TGFβ1 and GNB3 with the occurrence of primary vesicoureteral reflux

PURPOSE

Etiopathogenesis of VUR is composite and not fully understood. Many data indicate the importance of genetic predisposition. The aim of this study was to establish the relationship of selected polymorphisms: 14094 polymorphism of the ACE, polymorphism rs1800469 of TGFβ-1, rs5443 gene polymorphism of the GNB3 and receptor gene polymorphism rs5186 type 1 AGTR1 with the occurrence of the primary vesicoureteral reflux.

MATERIAL

The study included 190 children: 90 with the primary VUR confirmed with the voiding cystourethrogram and excluded secondary VUR and a control group of 100 children without a history of the diseases of the genitourinary tract.

METHODS

The study was planned in the scheme: "tested case versus control." Genomic DNA was isolated from the leukocytes of peripheral blood samples. The results were statistically analyzed in the Statistica 10 using χ ² test and analysis of the variance Anova.

RESULTS

Any of the four studied polymorphisms showed no difference in the distribution of genotypes between patients with primary vesicoureteral reflux and the control group. In patients with VUR and TT genotype polymorphism rs5443 GNB3 gene, the glomerular filtration rate was significantly higher than in patients with genotype CC or CT.

CONCLUSIONS

(1) No relationship was found between the studied polymorphisms (14094 ACE gene, rs1800469 gene TGFβ1, GNB3 gene rs5443, rs5186 AGTR1 gene) and the occurrence of primary vesicoureteral reflux. (2) TT genotype polymorphism rs5443 GNB3 gene may be a protective factor for the improved renal function in patients with primary vesicoureteral reflux in patients with genotype CC or CT.

Gene polymorphisms associated with functional dyspepsia

Functional dyspepsia (FD) is a constellation of functional upper abdominal complaints with poorly elucidated pathophysiology. However, there is increasing evidence that susceptibility to FD is influenced by hereditary factors. Genetic association studies in FD have examined genotypes related to gastrointestinal motility or sensation, as well as those related to inflammation or immune response. G-protein b3 subunit gene polymorphisms were first reported as being associated with FD. Thereafter, several gene polymorphisms including serotonin transporter promoter, interlukin-17F, migration inhibitory factor, cholecystocynine-1 intron 1, cyclooxygenase-1, catechol-o-methyltransferase, transient receptor potential vanilloid 1 receptor, regulated upon activation normal T cell expressed and secreted, p22PHOX, Toll like receptor 2, SCN10A, CD14 and adrenoreceptors have been investigated in relation to FD; however, the results are contradictory. Several limitations underscore the value of current studies. Among others, inconsistencies in the definitions of FD and controls, subject composition differences regarding FD subtypes, inadequate samples, geographical and ethnical differences, as well as unadjusted environmental factors. Further well-designed studies are necessary to determine how targeted genes polymorphisms, influence the clinical manifestations and potentially the therapeutic response in FD.

Ex vivo assessment of cellular immune function - applications in patient care and clinical studies

Cellular ex vivo assays have a broad range of applications in patient care and clinical studies, especially when they are standardized and highly sensitive. As compared to analyses by molecular genetics such as the single nucleotide polymorphism (SNP) testing, they are usually more global. These assays partly mimic the in vivo situation, relying on a complex interaction of various immune cells. For example, they can be used to determine modulation of alloresponses by treatment or underlying disease, diagnose and quantify primary and secondary cellular immunodeficiency, follow-up vaccination responses, measure adoptive transfer of virus-specific immunity via hematopoietic stem cell or liver transplantation, assess allergy, antimicrobial immunity and also rare effector/memory cells directed against tumor antigens. This review will first shortly describe various cellular in vitro methods and then present applications, summarizing some own studies performed within the last 18 years.

G-Protein β3-Subunit Gene C825T Polymorphism and Cardiovascular Risk: An Updated Review

Hypertension is a common disorder of multifactorial origin that constitutes a major risk factor for cardiovascular events such as stroke and myocardial infarction. The subunits of the heterotrimeric G proteins are attractive candidate gene products for susceptibility to hypertension, obesity and insulin resistance syndrome. A polymorphism (825C/T) in exon 10 of the GNB3 gene, encoding for the Gβ3 subunit, has been described. The 825T allele is associated with alternative splicing of the gene and formation of a truncated but functionally active β3 subunit. Many studies have investigated whether carriers of the 825T allele are at increased risk for hypertension, obesity, insulin-resistance and left ventricular hypertrophy with apparently conflicting results. The present review demonstrates that GNB3 825T allele is a useful genetic marker for better defining the risk profile of hypertensive patients, as it is associated with increased risk of stroke and myocardial infarction in longitudinal studies in Caucasians.

Sudden infant death syndrome and the genetics of inflammation

Several studies report signs of slight infection prior to death in cases of sudden infant death syndrome (SIDS). Based on this, a hypothesis of an altered immunological homeostasis has been postulated. The cytokines are important cellular mediators that are crucial for infant health by regulating cell activity during the inflammatory process. The pro-inflammatory cytokines favor inflammation; the most important of these are IL-1α, IL-1β, IL-6, IL-8, IL-12, IL-18, TNF-α, and IFN-γ. These cytokines are controlled by the anti-inflammatory cytokines. This is accomplished by reducing the pro-inflammatory cytokine production, and thus counteracts their biological effect. The major anti-inflammatory cytokines are interleukin-1 receptor antagonist (IL-1ra), IL-4, IL-10, IL-11, and IL-13. The last decade there has been focused on genetic studies within genes that are important for the immune system, for SIDS with a special interest of the genes encoding the cytokines. This is because the cytokine genes are considered to be the genes most likely to explain the vulnerability to infection, and several studies have investigated these genes in an attempt to uncover associations between SIDS and different genetic variants. So far, the genes encoding IL-1, IL-6, IL-10, and TNF-α are the most investigated within SIDS research, and several studies indicate associations between specific variants of these genes and SIDS. Taken together, this may indicate that in at least a subset of SIDS predisposing genetic variants of the immune genes are involved. However, the immune system and the cytokine network are complex, and more studies are needed in order to better understand the interplay between different genetic variations and how this may contribute to an unfavorable immunological response.

G protein β3 subunit polymorphism and long-term prognosis of functional dyspepsia

Background/Aims

A link between G protein β3 (GNB3) polymorphism and functional dyspepsia (FD) has been suggested. The aim of this study was to determine the role of GNB3 polymorphism in the long-term prognosis of FD in Koreans.

Methods

FD patients and normal healthy controls were recruited from patients who visited our center between December 2006 and June 2007. All of the subjects completed Rome III questionnaires before undergoing upper gastrointestinal endoscopy and colonoscopy. Genomic DNA was extracted for GNB3 genotyping. After 5 years, the subjects were reevaluated using the same questionnaires.

Results

GNB3 825T carrier status was significantly related to FD in Koreans (p=0.04). After 5 years, 61.0% of the initial FD patients and 12.2% of the initial normal subjects were diagnosed with FD (odds ratio [OR], 11.7; 95% confidence interval [CI], 4.3 to 31.1; p<0.001). Regardless of the GNB3 genotype (p=0.798), female sex was strongly correlated with FD after 5 years (OR, 3.3; 95% CI, 1.2 to 9.1; p=0.017).

Conclusions

The T allele of GNB3 is linked to FD in Koreans but does not predict long-term prognosis. Female sex is related to a higher prevalence of FD after 5 years.

Expression of NTRK1/TrkA affects immunogenicity of neuroblastoma cells

High levels of the NTRK1/TrkA receptor are expressed in low-stage neuroblastomas, which are characterized by a good patient prognosis and often undergo spontaneous regression. In addition to apoptosis, tumor-immune responses might contribute to this regression. We hypothesized that TrkA expression might enhance the immune response to neuroblastomas. Immunohistochemistry on neuroblastoma tissue microarrays confirmed significantly higher lymphocyte infiltration in low-stage compared with high-stage tumors. Flow cytometry of human SH-SY5Y cells stably transfected with NTRK1/TrkA cDNA revealed significant upregulation of major histocompatibility complex (MHC) class I complexes on TrkA-expressing cells. Corresponding to this upregulation, T cell activity and cytoxicity was enhanced in the presence of SY5Y-TrkA cells or by medium conditioned by them, suggesting the existence of additional soluble factors stimulating the T cell response. Activation of natural killer (NK) cells was only increased in the presence of SY5Y-TrkA conditioned medium (CM) and not in co-culture assays, suggesting a dominant inhibitory effect of upregulated MHC class I as the primary NK cell escape mechanism of TrkA-expressing neuroblastomas. We reanalyzed gene expression data obtained from the cell culture model to identify additional genes involved in the TrkA-mediated modulation of immune responses. Upregulation of selected target genes in SY5Y-TrkA cells was confirmed on transcript and protein levels. However, none of the proteins were detected in medium conditioned by SY5Y-TrkA cells, arguing against these factors as soluble mediators of the TrkA-induced immune response. We here provide evidence that TrkA expression in neuroblastoma leads to an increased immunogenicity that may contribute to a less malignant phenotype and/or spontaneous regression of neuroblastoma cells.

The evolutionary significance of depression in Pathogen Host Defense (PATHOS-D)

Given the manifold ways that depression impairs Darwinian fitness, the persistence in the human genome of risk alleles for the disorder remains a much debated mystery. Evolutionary theories that view depressive symptoms as adaptive fail to provide parsimonious explanations for why even mild depressive symptoms impair fitness-relevant social functioning, whereas theories that suggest that depression is maladaptive fail to account for the high prevalence of depression risk alleles in human populations. These limitations warrant novel explanations for the origin and persistence of depression risk alleles. Accordingly, studies on risk alleles for depression were identified using PubMed and Ovid MEDLINE to examine data supporting the hypothesis that risk alleles for depression originated and have been retained in the human genome because these alleles promote pathogen host defense, which includes an integrated suite of immunological and behavioral responses to infection. Depression risk alleles identified by both candidate gene and genome-wide association study (GWAS) methodologies were found to be regularly associated with immune responses to infection that were likely to enhance survival in the ancestral environment. Moreover, data support the role of specific depressive symptoms in pathogen host defense including hyperthermia, reduced bodily iron stores, conservation/withdrawal behavior, hypervigilance and anorexia. By shifting the adaptive context of depression risk alleles from relations with conspecifics to relations with the microbial world, the Pathogen Host Defense (PATHOS-D) hypothesis provides a novel explanation for how depression can be nonadaptive in the social realm, whereas its risk alleles are nonetheless represented at prevalence rates that bespeak an adaptive function.

The role of 5-HTT LPR and GNβ3 825C>T polymorphisms and gene-environment interactions in irritable bowel syndrome (IBS)

BACKGROUND

Smaller studies have evaluated SLC6A4 5-HTTLPR and GNβ3 825C>T polymorphisms in IBS, and interactions between 5-HTT LPR with life events have been reported in the psychiatric literature, but gene-environment studies in IBS are lacking.

AIMS

The purpose of this study was to assess the association of two polymorphisms with IBS and age of onset, and whether there are gene-environment interactions with IBS.

METHODS

Outpatients with IBS and controls completed a validated questionnaire and provided blood for DNA. Comparisons of genotype/allele frequencies between cases and controls were performed with logistic regression. Linear regression was used to evaluate the association between the variants and age of onset. Environmental variables tested included abuse, parental alcohol abuse, parental psychiatric disorders, and gastrointestinal infections.

RESULTS

Genotyping was performed in 385 cases and 262 controls with median age of 50 years (range, 18.0-70.0) and 498 (77 %) females. The IBS subtype distribution among cases was: 102 (26 %) D-IBS, 40 (10 %) C-IBS, 125 (32 %) M-IBS, 118 (31 %) other. No association was observed between IBS or age of onset and both variants. Significant interactions were observed between GI infection and the GNβ3 825T allele. For those reporting gastrointestinal infection, the OR for IBS was 3.9 (95 % CI 1.2-12.7) whereas the OR was 0.86 (95 % CI 0.65-1.13) for those without prior infection.

CONCLUSIONS

There was a significant interaction between the GNβ3 polymorphism and infection in the development of IBS, suggesting that its etiology is the result of a combination of specific genetic and environmental risk factors.

The Gβ3 splice variant associated with the C825T gene polymorphism is an unstable and functionally inactive protein

A splice variant of Gβ3, termed Gβ3s, has been associated with the C825T polymorphism in the Gβ3 gene and linked with many human disorders. However, the biochemical properties and functionality of Gβ3s remain controversial. Here, using multidisciplinary approaches including co-immunoprecipitation analysis and bioluminescence resonance energy transfer (BRET) measurements, we showed that unlike Gβ3, Gβ3s failed to form complexes with either Gγ or Gα subunits. Moreover, using a mutant Gγ2 deficient in lipid modification to purify Gβ3s from Sf9 cells without the use of detergents, we further showed that the failure of Gβ3s to form dimers with Gγ was not due to the instability of the dimers in detergents, but rather, reflected the intrinsic properties of Gβ3s. Additional studies indicated that Gβ3s is unstable, and unable to localize properly to the plasma membrane and to activate diverse Gβγ effectors including PLCβ2/3, PI3Kγ, ERKs and the Rho guanine exchange factor (RhoGEF) PLEKHG2. Thus, these data suggest that the pathological effects of Gβ3 C825T polymorphism may result from the downregulation of Gβ3 function. However, we found that the chemokine SDF1α transmits signals primarily through Gβ1 and Gβ2, but not Gβ3, to regulate chemotaxis of several human lymphocytic cell lines, indicating the effects of Gβ3 C825T polymorphism are likely to be tissue and/or stimuli specific and its association with various disorders in different tissues should be interpreted with great caution.

G Protein β3 subunit gene C825T polymorphism and its association with the presence and clinicopathological characteristics of prostate cancer

PURPOSE

A C825T polymorphism in the GNB3 gene encodes the Gβ3 subunit of heterotrimeric G proteins. Due to increased G protein activation the GNB3 825T allele, a truncated form of the G3 protein, is associated with enhanced signal transduction capacity. This splice variant is associated with various malignant diseases. We investigated the possible association of GNB3 gene polymorphism with prostate cancer and its clinicopathological characteristics.

MATERIALS AND METHODS

Using polymerase chain reaction and restriction fragment length polymorphism the allele frequency of the C825T polymorphism was investigated in 172 patients with prostate cancer. Results were compared with those of 344 age matched, healthy blood donors.

RESULTS

The frequency of the GNB3 825T allele in patients with prostate cancer was significantly higher than in controls (49.1% vs 42.7%, OR 3.76, p = 0.003). Patients with prostate cancer who had the TT genotype were at 2.52 times higher risk for prostate cancer than the CC genotype referent group (OR 2.22, 95% CI 1.18-4.22, p = 0.008). Accordingly a significant increased risk of advanced disease was observed in men carrying the GNB3 TT genotype compared with those homozygous for the wild-type C allele (OR 6.24, 95% CI 4.16-12.45, p = 0.001). Men lacking the C825 allele were at approximately sevenfold higher risk for high grade (Gleason score greater than 7) prostate cancer than men with the GNB3 CC genotype.

CONCLUSIONS

Our study presents preliminary but intriguing data suggesting that GNB3 gene polymorphism influences susceptibility to prostate cancer.

G-Protein Beta3 Subunit C825T Polymorphism in Patients With Overlap Syndrome of Functional Dyspepsia and Irritable Bowel Syndrome

Background/Aims

Guanine nucleotide binding protein (G-protein) beta polypeptide 3 (GNB3) C825T polymorphism alters intracellular signal transduction, which may lead to motor or sensory abnormalities of the gastrointestinal tract. The aim of the present study was to evaluate the association of the GNB3 C825T polymorphism with susceptibility to overlap syndrome of functional dyspepsia (FD) and irritable bowel syndrome (IBS) in a Korean population.

Methods

One hundred sixty-seven patients with FD alone, 60 patients with IBS alone, 85 patients with the overlap of FD and IBS, and 434 asymptomatic healthy subjects participated in the study. Genotyping for GNB3 C825T polymorphism was performed using their blood samples.

Results

No association of GNB3 genotypes in patients with FD alone, IBS alone or overlap phenotype, when compared to genotypes in controls, was detected. The frequency of CT and TT genotypes relative to the CC genotype for the phenotypes of FD alone, IBS alone and the coexistence of FD and IBS did not significantly differ. Comparison of the TT genotype with the CC/CT genotype showed no significant association for each phenotype group.

Conclusions

There is no apparent association of the GNB3 C825T polymorphism with the susceptibility to FD, IBS or the overlap of FD and IBS. Larger-scale studies and further investigation on other candidate genes are required.

The role of G protein gene GNB3 C825T polymorphism in HIV-1 acquisition, progression and immune activation

Background

The GNB3 C825T polymorphism is associated with increased G protein-mediated signal transduction, SDF-1α-mediated lymphocyte chemotaxis, accelerated HIV-1 progression, and altered responses to antiretroviral therapy among Caucasian subjects. The GNB3 825T allele is highly prevalent in African populations, and as such any impact on HIV-1 acquisition or progression rates could have a dramatic impact. This study examines the association of the 825T polymorphism with HIV-1 acquisition, disease progression and immune activation in two African cohorts. GNB3 825 genotyping was performed for enrolees in both a commercial sex worker cohort and a perinatal HIV transmission (PHT) cohort in Nairobi, Kenya. Ex vivo immune activation was quantified by flow cytometry, and plasma chemokine levels were assessed by cytokine bead array.

Results

GNB3 genotype was not associated with sexual or vertical HIV-1 acquisition within these cohorts. Within the Pumwani cohort, GNB3 genotype did not affect HIV-1 disease progression among seroconverters or among HIV-1-positive individuals after adjustment for baseline CD4 count. Maternal CD4 decline and viral load increase in the PHT cohort did not differ between genotypes. Multi-parametric flow cytometry assessment of T cell activation (CD69, HLA-DR, CD38) and Treg frequency (CD25⁺FOXP3⁺) found no differences between genotype groups. Plasma SDF-1α, MIP-1β and TRAIL levels quantified by cytokine bead array were also similar between groups.

Conclusions

In contrast to previous reports, we were unable to provide evidence to suggest that the GNB3 C825T polymorphism affects HIV-1 acquisition or disease progression within African populations. Ex vivo immune activation and plasma chemokine levels were similarly unaffected by GNB3 genotype in both HIV-1-negative and HIV-1-positive individuals. The paucity of studies investigating the impact of GNB3 polymorphism among African populations and the lack of mechanistic studies make it difficult to assess the true biological significance of this polymorphism in HIV-1 infection.

G-protein β3 subunit 825CC genotype is associated with postprandial distress syndrome with impaired gastric emptying and with the feeling of hunger in Japanese

BACKGROUND

G-protein dysfunction related alteration of intracellular signal transduction might be linked to various abnormalities of functional gastrointestinal (GI) disorders. Serotonin (5-hydroxytryptamine; 5-HT) as well as G-protein is also key signaling molecule sensorimotor functions in the GI tract. Thus, this study aims to evaluate the correlation between gastric emptying and GNβ3 and 5-HTs polymorphisms in functional dyspepsia (FD) as defined by Rome III classification.

METHODS

Seventy-four patients presenting with typical symptoms of FD (epigastric pain syndrome: EPS, n=24; postprandial distress syndrome: PDS, n = 51) and sixty-four healthy volunteers were enrolled. Gastric motility was evaluated with the T(max) value using the (13) C-acetate breath test. We used Rome III criteria to evaluate upper abdominal symptoms and SRQ-D scores to determine depression status. GNβ3-C825T, 5-HT(1A) -C1019G, 5-HT(2A) -G1438A, 5-HT(3A) -C42T, and 5-HT(4A) -G353+6A polymorphisms were analyzed in DNA from blood samples of enrolled subjects. Genotyping was performed by polymerase chain reaction.

KEY RESULTS

There was a significant relationship (P=0.045) between GNβ3 825CC genotype and PDS patients without gastro-esophageal reflux symptoms with impaired gastric emptying. In Japanese, GNβ3 825CC genotype in FD patients was significantly associated (P=0.0485) with the feeling of hunger compared with GNβ3 825CT and TT genotypes.

CONCLUSIONS & INFERENCES

  Our results suggest that the GNβ3 825CC genotype is significantly associated with PDS patients without gastro-esophageal reflux with impairments of gastric emptying and also with the feeling of hunger in patients with FD. Further studies are needed to clarify whether the GNβ3 825CC genotype is linked to disturbances of gastric emptying via altered signal transduction responses.

Reduced prevalence of the C825T polymorphism of the G-protein beta subunit gene in women with breast cancer

OBJECTIVE

To evaluate the prevalence of the C825T polymorphism in the GNB3 gene in women with and without breast cancer and its possible association with clinical or pathological features of breast disease.

SUBJECTS AND METHODS

We included 134 women with breast cancer and a control group of 129 healthy women. The case group responded to a questionnaire on lifestyle, reproductive factors and family history. Clinical data were also evaluated. The risk for cancer was calculated and PCR was carried out for the detection of the polymorphism. Statistical analysis was performed using the package R Environment, with confidence intervals of 95% and a significance level of 5% (p and lt;0.05).

RESULTS

The frequency of the TT genotype was significantly greater in women of the control group (30.2%) than women with breast cancer (14.9%) (p=0.02). The polymorphism was not associated with clinical features, age at diagnosis (p=0.07), age at menarche (p=0.17), and age at menopause (p=0.60). The TT genotype did not have a higher frequency in patients with high BMI (p=0.98). The risk for cancer showed no correlation with the presence of the polymorphism.

CONCLUSIONS

Our data indicate that the C825T polymorphism in the GNB3 gene has no relationship to the risk for breast cancer or the characteristics of the disease.

SNPs in genes encoding G proteins in pharmacogenetics

Heterotrimeric guanine-binding proteins (G proteins) transmit signals from the cell surface to intracellular signal cascades and are involved in various physiological and pathophysiological processes. Polymorphisms in the genes GNB3 (encoding the Gβ3 subunit), GNAS (encoding the Gαs subunit) and GNAQ (encoding the Gαq subunit) have been the primary focus of investigation. Polymorphisms in these genes could be associated with different complex phenotypes underlining that alterations in G-protein signaling can cause multiple disorders. G proteins present a point of convergence or ‘bottleneck’ between various receptors and effectors, thus making them a sensible tool for pharmacogenetic studies. The pharmacogenetic studies performed to date mostly demonstrate an association between G-protein polymorphisms and response to therapy or occurrence of adverse drug effects. Therefore, polymorphisms in genes encoding G-protein subunits may help to individualize drug treatment in various diseases with regard to both efficacy and safety.

The CC Genotype of the C825T Polymorphism of the G Protein β3 Gene (GNB3) is Associated with a High Relapse Rate in Patients with Chronic Lymphocytic Leukaemia

A C825T polymorphism has been described in the GNB3 gene which encodes the Gbeta3 subunit of heterotrimeric G proteins. The GNB3 825T allele is predictive of enhanced Gi protein activation. This study was performed to correlate genotypes of the C825T polymorphism with various clinical aspects of chronic lymphocytic leukaemia (B-CLL). The GNB3 genotype distribution in B-CLL patients was similar to that in other Caucasian populations, arguing against a role of the polymorphism in the susceptibility to develop B-CLL. No statistically significant differences were observed at diagnosis between patients with the CC genotype and homozygous or heterozygous T allele carriers with respect to age at disease onset, sex distribution, proportion of patients with CD38+ leukaemia or patients in Binet stage A, blood cell counts, degree of bone marrow infiltration or serum levels of lactate dehydrogenase, thymidine kinase or beta2-microglobulin. In a subgroup of 44 patients requiring chemotherapy, the median interval between diagnosis and first treatment and the response to treatment were similar in patients with CC or CT/TT genotypes. A statistically significant difference, however, was found in the proportion of patients relapsing and requiring second line chemotherapy (CC: 95%; CT/TT: 52%; p = 0.0043). The GNB3 genotype (p = 0.024) and age (p = 0.042) were identified as independent prognostic factors for a second therapy. Thus, the long-term success of the treatment appears to be correlated with the GNB3 genotype.

Viral hepatitis: human genes that limit infection

Treatment response and susceptibility to chronic viral hepatitis C and B may be modified by host genetic factors. The majority of genetic variants that confer a significant risk have been localized in genes involved in immune response. However, many findings could not be replicated and almost none of the identified risk factors had a noticeable impact on clinical decisions. In contrast, recent findings in independent large genome wide association studies confirmed genetic variants in the interferon gamma gene locus as strong predictors of outcome with outstanding clinical relevance. This review gives an overview on significant genetic susceptibility factors for susceptibility and treatment outcome in chronic viral hepatitis C and B that have been identified by the classical candidate gene approach and genome wide studies and also highlights some recent findings on genetic factors for common adverse drug reactions.

Pharmacogenetics and pharmacogenomics of sexual dysfunction: current status, gaps and potential applications

Although treatment of different types of sexual dysfunction has improved in the past decade with the introduction of phosphodiesterase type 5 inhibitors and selective serotonin reuptake inhibitors, response rates to these targeted therapies are variable. There are a number of studies in the published literature that provide proof-of-concept that genetic variation contributes to the variable response. Pharmacogenomics will most likely be one part of our therapeutic armamentarium in the future and will provide a stronger scientific basis for optimizing drug therapy on the basis of each patient’s genetic constitution. This article will review English language medical literature on the state-of-the-art genetic polymorphisms of drug targets, transporters and signaling molecules as well as pharmacogenetic studies of sexual dysfunction and suggested possible applications. Collectively, the data demonstrate that pharmacogenomics in the field of sexual medicine is still in its infancy. More research will provide further intriguing new discoveries in years to come.

Role of C825T Polymorphism of GNβ3 Gene in Preeclampsia

OBJECTIVE

The main objective of the study was to understand the role of C825T polymorphism that generates a splice variant in the beta3 subunit of heterotrimeric G-protein in preeclampsia.

RESULTS

We analyzed genomic DNA of 151 women with preeclampsia (72 Caucasians and 79 African-Americans) and 198 women with normal delivery (102 Caucasians and 96 African-Americans) for C825T polymorphism of GNbeta3 gene. The T-allele frequency in Caucasian women with preeclampsia was 0.42 as compared to 0.25 in normal pregnant women (p = 0.0004) and in African-American women with preeclampsia was 0.82 as compared to 0.68 in normal pregnant women (p = 0.0028).

CONCLUSIONS

Results of these experiments show that the allele frequency of C825T polymorphism is significantly different in women with preeclampsia compared with women with normal delivery in Caucasian as well as African-American population.

Association study of the G-protein beta3 subunit C825T polymorphism with disease progression an overall survival in patients with head and neck squamous cell carcinoma

The T-allele of a common C825T single nucleotide polymorphism (SNP) in the gene GNB3, encoding the G3 subunit of heterotrimeric G-proteins, is associated with a truncated form of the G3 protein that imparts a greater signaling capacity than the alternative C-allele encoding a nontruncated protein. We analyzed the C825T-allele status with regard to disease progression in patients with head and neck squamous cell carcinoma (HNSCC). The prognostic value of the SNP was evaluated in an unselected series of 341 patients treated with curative intent for HNSCC including all tumor stages with different therapeutic regimens. Genotype analysis was done by Pyrosequencing using DNA from paraffin-embedded tissue samples. Genotypes were correlated with relapse-free and overall survival. Proportions of 5-year relapse-free intervals were 62% for CC, 60% for TC, and 42% for TT genotypes. Kaplan-Meier curves revealed a significant genotype-dependent relapse-free interval (P = 0.036). In multivariate analysis with stage, localization, grade, gender, and smoking habits as covariates, GNB3 825T homozygous patients displayed a higher risk for relapse than C825 homozygous patients (TT versus CC, hazard ratio; 95% confidence interval, 1.4-4.8; P = 0.002). The same genotype effect was found for overall survival, TT genotypes were at higher risk for death compared with CC genotypes (hazard ratio, 2.6; 95% confidence interval, 1.6-4.3; P < 0.001), and 5-year survival proportions were 60% for CC, 52% for TC, and 33% for TT. The GNB3 C825T SNP thus represents a host derived prognostic marker in HNSCC, which allows identifying high-risk patients, which could benefit from novel and/or more aggressive therapeutic regimes.

Candidate genotypes associated with functional dyspepsia

There is accumulating evidence of a genetic predisposition for developing a functional gastrointestinal (GI) disorder. Identification of the genetic factors may improve understanding of underlying pathophysiological mechanisms. We aimed to test the association of functional polymorphisms in genes involved in serotonergic signalling and G-protein-mediated signal transduction, both affecting gastroduodenal sensory and motor function, with functional dyspepsia (FD). FD patients, send to our tertiary referral centre, were studied (n = 112). Healthy controls (n = 336) free of GI symptoms were matched 1 : 3 for age and gender. Polymorphisms in genes encoding the serotonin receptor type three A subunit (HTR3A), the serotonin transporter (SERT) and the G-protein beta3 subunit (GNB3) were analysed. The FD patients displayed a higher prevalence of the T allele of the GNB3 C825T polymorphism compared to healthy controls (OR = 1.60, 95% CI: 1.03-2.49, P = 0.038). No association between FD and the genotype of the insertion/deletion polymorphism in the promoter of SERT (SERT-P) or HTR3A C178T polymorphism was observed. Tertiary referral FD is associated with the 825T allele of the GNB3 gene. The increased signal transduction associated with this allele may contribute to the abnormalities in gastroduodenal sensory and motor function observed in FD.

Host genetic factors and vaccine-induced immunity to hepatitis B virus infection

Background

Vaccination against hepatitis B virus infection (HBV) is safe and effective; however, vaccine-induced antibody level wanes over time. Peak vaccine-induced anti-HBs level is directly related to antibody decay, as well as risk of infection and persistent carriage despite vaccination. We investigated the role of host genetic factors in long-term immunity against HBV infection based on peak anti-HBs level and seroconversion to anti-HBc.

Methods

We analyzed 715 SNP across 133 candidate genes in 662 infant vaccinees from The Gambia, assessing peak vaccine-induced anti-HBs level and core antibody (anti-HBc) status, whilst adjusting for covariates. A replication study comprised 43 SNPs in a further 393 individuals.

Results

In our initial screen we found variation in IFNG, MAPK8, and IL10RA to affect peak anti-HBs level (GMTratio of <0.6 or >1.5 and P≤0.001) and lesser associations in other genes. Odds of core-conversion was associated with variation in CD163. A coding change in ITGAL (R719V) with likely functional relevance showed evidence of association with increased peak anti-HBs level in both screens (1st screen: s595_22 GMTratio 1.71, P = 0.013; 2nd screen: s595_22 GMTratio 2.15, P = 0.011).

Conclusion

This is to our knowledge the largest study to date assessing genetic determinants of HBV vaccine-induced immunity. We report on associations with anti-HBs level, which is directly related to durability of antibody level and predictive of vaccine efficacy long-term. A coding change in ITGAL, which plays a central role in immune cell interaction, was shown to exert beneficial effects on induction of peak antibody level in response to HBV vaccination. Variation in this gene does not appear to have been studied in relation to immune responses to viral or vaccine challenges previously. Our findings suggest that genetic variation in loci other than the HLA region affect immunity induced by HBV vaccination.

The GNB3 C825T polymorphism affects response to HCV therapy with pegylated interferon in HCV/HIV co-infected but not in HCV mono-infected patients

BACKGROUND/AIMS

Response to HCV treatment with pegylated interferon-alpha is variable but might at least in part depend on genetic host factors. The G protein beta3 unit (GNB3) C825T polymorphism has been shown to affect treatment response in HCV mono-infection. Here, we analyzed the impact of the GNB3 genotype in the context of HCV/HIV co-infection.

METHODS

HIV/HCV co-infected (n=112) and HCV mono-infected patients (n=150), receiving therapy with pegylated IFN-alpha/ribavirin, were enrolled into this study. Furthermore, we analyzed 220 healthy and 92 HIV mono-infected patients. GNB3 genotype was defined and correlated with respect to treatment response.

RESULTS

GNB3 genotype distribution differed significantly between HIV/HCV co-infected patients and HIV-positive/HCV-negative (p=0.0002) or healthy controls (p=0.03). Patients with a GNB3 CC genotype had significantly lower SVR rates as compared to carriers of a non-CC genotype (52% versus 77%; p=0.018). In a logistic regression analysis the GNB3 genotype and the HCV genotype were significantly associated with response to treatment (p=0.018). In contrast to HIV/HCV co-infected patients, GNB3 genotype did not affect response to treatment in HCV mono-infected patients.

CONCLUSIONS

The GNB3 825 CC genotype is associated with poor SVR rates in HIV/HCV co-infected patients. This underlines the impact of genetic host factors for treatment response.

A genetic association study of 5-HTT LPR and GNbeta3 C825T polymorphisms with irritable bowel syndrome

A pharmacogenetic study suggests the 5-HTT LPR polymorphism predicts response to alosetron, and another study describes a possible association of the GNbeta3 C825T polymorphism with IBS in patients with dyspepsia. We performed a case-control association study to determine whether these polymorphisms are associated with irritable bowel syndrome (IBS). The study aim was to compare allele and genotype frequencies between cases and controls for the 5-HTT LPR and the GNbeta3 C825T polymorphism. Cases were 50 GI outpatients; controls were 53 General Medicine outpatients matched to cases for age, gender and race at a major medical centre. Participants completed a questionnaire and donated blood. DNA was genotyped using polymerase chain reaction based assays. Eighty-two per cent of cases met Rome II criteria for IBS: 12% constipation-, 46% diarrhoea-, and 42% mixed-IBS. Genotype and allele frequencies for both polymorphisms did not differ between cases and controls. However, the allele frequency of the short (S) allele of the 5-HTT LPR polymorphism was greater in those with mixed-IBS compared with controls (68%vs 45%, P < 0.05). This study suggests that the 5-HTT LPR polymorphism may be associated with mixed-IBS, but not IBS overall. No association was observed for the GNbeta3 C825T polymorphism with IBS overall or subtypes.

Clinical application of pharmacogenetics in gastrointestinal diseases

As knowledge of the human genome grows, there will be a direct impact on the management of specific diseases. Within gastroenterology and hepatology, there has been a change in the understanding of how variations or mutations in genes involved in drug metabolism or disease pathophysiology affect response to therapy. This review discusses the application of clinical pharmacogenetics to the following diseases and disorders: inflammatory bowel disease, Helicobacter pylori infections, gastroesophageal reflux disease, irritable bowel syndrome, functional dyspepsia, liver transplantation and colon cancer. Although only a few genotyping tests are regularly used in clinical practice, it is anticipated that studies will propel the routine use of many of the tests described in this review, in the future.

The G protein beta3 subunit 825C allele is associated with sudden infant death due to infection

AIM

To investigate the Gbeta3 subunit C825T polymorphism with regard to sudden unexpected infant death. The reported association between the Gbeta3s protein and increased immune cell function in humans makes this polymorphism highly interesting both with regard to sudden infant death syndrome (SIDS) and deleterious infectious disease.

METHODS

The cases investigated in the present study consist of 250 SIDS cases, 38 cases of sudden unexpected infant death due to infection and 99 living infant controls. Typing of the C825T polymorphism was performed by real-time PCR with allele-specific probes and melting curve analyses.

RESULTS

The cases of infectious death have a higher percentage of both the C allele (p=0.037 compared to the SIDS cases, p=0.022 compared to the controls) and the CC genotype (p=0.05 compared to the SIDS cases, p=0.016 compared to the controls). There were no differences between SIDS cases and controls.

CONCLUSION

The observed association between the 825C allele and infectious death may indicate that the presence of the 825T allele exerts a protective effect towards serious infection, possibly through enhanced G protein signalling. The C allele, on the other hand, appears to represent a disadvantage in this regard.

ELISpot assay as a sensitive tool to detect cellular immunity following influenza vaccination in kidney transplant recipients

Enhanced cellular immunity following influenza vaccination has been undetectable in kidney transplant recipients so far. Protection from influenza is dependent on cellular and humoral immunity. Aim of the study was to investigate immune responses before and after vaccination with influenza A and B antigens in 65 kidney transplant recipients. A significant increase in proliferative responses was only observed towards influenza B (P < 0.0001) by lymphocyte transformation test. The enzyme-linked immunospot (ELISpot) assay was more sensitive and detected significant, 3- to 5-fold increases (P < 0.0001) in interferon-gamma secretion using influenza A and B antigens. Furthermore, influenza antibody titers increased significantly (P < 0.0001). At month 1 post-vaccination 85% of patients displayed specific cellular, and 95% or 92% humoral immunity against influenza A and B, respectively. Thus, applying the sensitive ELISpot assay, influenza-specific cellular immunity could be detected for the first time in kidney transplant recipients after vaccination.

Studies of the association of the GNB3 825C>T polymorphism with components of the metabolic syndrome in white Danes

AIMS/HYPOTHESIS

The 825C>T polymorphism in the gene encoding the G protein beta3 subunit (GNB3) causes enhanced G protein activation and increased in vitro cell proliferation. This polymorphism is also repeatedly associated with an increased risk of hypertension and has been studied in relation to obesity with divergent results. Only a few association studies have investigated whether this polymorphism is related to type 2 diabetes or the metabolic syndrome. We estimated the impact of the GNB3 825C>T polymorphism in relatively large-scale association studies of common phenotypes of the metabolic syndrome.

MATERIALS AND METHODS

The GNB3 825C>T polymorphism was genotyped in 7,518 white Danish subjects using mass spectrometry analysis of PCR products. Case-control studies were undertaken for obesity, hypertension, type 2 diabetes and the metabolic syndrome, and a meta-analysis including data from the present study and previous studies of hypertension was performed. Quantitative trait studies of metabolic variables were carried out in 4,387 glucose-tolerant subjects.

RESULTS

We observed minor differences in 825C>T genotype distributions for type 2 diabetes (CC/CT/TT 49/41/10% (control) vs 46/46/9% (cases), respectively, p=0.007); however, after correction for multiple testing, these were not statistically significant. No association was found with hypertension, obesity or the metabolic syndrome. Curiously, the T allele was associated with nominally lower systolic and diastolic blood pressure levels-a finding in contrast with most previous studies-but not with other metabolic variables. Meta-analysis demonstrated a high degree of heterogeneity between study populations of different ethnic origin. Although there was a tendency towards an increased risk of hypertension among 825T allele carriers, this was not statistically significant.

CONCLUSIONS/INTERPRETATION

The present study suggests no major involvement of the GNB3 825C>T polymorphism in components of the metabolic syndrome.

The genetics of irritable bowel syndrome

Because of the heterogeneity in symptoms and diagnostic findings, patients with irritable bowel syndrome (IBS) remain a challenge to treat and to study. This difficulty stems from lack of understanding of the pathophysiology of this disorder. Environmental factors likely play an important role in the pathogenesis and clinical manifestations of IBS. Several recent studies suggest a genetic basis for IBS, either in etiology or predicting response to therapy. Because of interest in studying the genetic contributors to this and other functional gastrointestinal disorders, we review the literature on genetic risk factors that might explain the familial clustering of IBS. Familial aggregation studies and twin studies suggest a modest contribution of genetics to the development of IBS. Pharmacogenomic and association studies provide stronger, although far from conclusive, evidence for genetic variants that affect expression of IBS. Together, these studies suggest that a multidisciplinary approach with clinical and psychological tools, epidemiologic methods, and genetic techniques might help elucidate the molecular components leading to the common symptoms of IBS and result in better treatments for those with IBS.

GNB3 C825T polymorphism and response to interferon-alfa/ribavirin treatment in patients with hepatitis C virus genotype 1 (HCV-1) infection

BACKGROUND/AIMS

The outcome of infection with the hepatitis C virus (HCV) has been shown to be influenced by genetic host factors. The G protein beta3 subunit (GNB3) C825T polymorphism has been shown to determine immune cell functions in vitro. We investigated the association of GNB3 genotypes with treatment response in HCV-infected patients.

METHODS

We genotyped 1781 HCV-free blood donors and 232 HCV-infected patients treated with interferon-alfa/ribavirin. Sustained virologic response (SVR) was defined by undetectable HCV-RNA 24 weeks after discontinuation of therapy. Non-response (NR) was defined by positive HCV-RNA at the end of at least 24 weeks of treatment. GNB3 genotypes were determined by DNA restriction enzyme analyses.

RESULTS

Genotype distribution was not significantly different in healthy controls and HCV-infected patients. Only in HCV genotype 1-infected patients a significant correlation between GNB3 CC genotype and NR could be observed (6 TT, 42 TC, 54 CC) versus SVR (11 TT, 25 TC, 19 CC) patients (P = 0.004). In a logistic regression analysis including biochemical and virologic characteristics, only GNB3 CC genotype was significantly associated with NR (OR 4.9; 95% CI = 1.4-16.5; P = 0.011).

CONCLUSIONS

The GNB3 825 CC genotype is associated with NR in HCV-1-infected patients.

Association study of the G-protein β3 subunit C825T polymorphism with disease progression in patients with bladder cancer

The T-allele in the GNB3 C825T polymorphism has been associated with increased cell migration, a prerequisite for metastasis. In this study we investigated a potential association of the C825T-allele status and disease progression in patients with transitional cell carcinoma of the bladder (TCC). Genotyping of the GNB3 C825T polymorphism was performed in 389 patients with transitional cell carcinoma of the bladder and in 104 control subjects and clinical follow-up was worked up in 339 patients. Genotype distribution in 389 patients with bladder cancer was comparable to genotype distribution of the control group. There was no association of GNB3 C825T genotype with tumor stage or grade, but follow-up analysis in the subgroup of non-smokers revealed a shorter time to metastasis in 825T-allele carriers compared to individuals homozygous CC. The genotype of the GNB3 C825T polymorphism appears to influence the biological behavior of tumor disease in non-smoking TCC patients.

Quantification of allele-specific G-protein beta3 subunit mRNA transcripts in different human cells and tissues by Pyrosequencing

The G-protein 825T allele is associated with altered drug responses while the underlying mechanism is not fully understood. Differential expression of transcripts from the C and T alleles could contribute to this process. The C825T polymorphism located in exon 10 is in close linkage disequilibrium with the A(-350)G promoter single nucleotide polymorphism (SNP) and the C1429T SNP and could therefore serve as a marker for allele-specific expression resulting from the promoter SNP. However, alternative splicing of exon 10 in 825T allele carriers may result in under-represented mRNA transcripts. We, therefore, established a novel method based on the Pyrosequencing technology to quantify allele-specific transcript expression and quantified the allelic variance of the C1429T polymorphism located in the 3'-untranslated region of GNB3. Validation of the method was performed using linear regression analysis of measured versus expected ratios of DNA mixed at different known concentrations as well as determining allele-specific mRNA expression of the partially imprinted IGF-2 gene. We genotyped the C1429T polymorphism of 83 samples derived from six different human tissues and cell lines and quantified mRNA transcripts from different alleles using heterozygous samples. No significantly different transcript amounts from the two alleles were found. There were also no significantly different transcript amounts associated with different G(-350)A genotypes (P>0.05). As a result, we could show that Pyrosequencing provides a sensitive tool to quantify allele-specific transcript expression. Our data do not support the hypothesis that differential G-protein activity associated with the C825T SNP results from different transcript amounts associated with specific GNB3 genotypes.