Barbara Gawrońska-Szklarz

Effect of CYP2C19*17 gene variant on Helicobacter pylori eradication in peptic ulcer patients

ObjectiveEradication of Helicobacter pylori is an important treatment strategy in peptic ulcer patients. Current regimens of eradication consist of proton pump inhibitor (PPI) and two antibiotics. The principal enzyme involved in PPIs metabolism is CYP2C19, which exhibits an interindividual variability of activity, mainly due to genetic polymorphism. Two alleles (CYP2C19*2 and CYP2C19*3), responsible for slow PPIs metabolism, were previously associated with higher efficacy of eradication. Recently, a novel CYP2C19 gene variant (CYP2C19*17), associated with faster metabolism of CYP2C19 substrates, was described. In the present study, a potential association between CYP2C19*17 allele and lower H. pylori eradication efficacy was tested in a group of peptic ulcer patients.MethodsA total of 125 peptic ulcer patients, positive for H. pylori infection, were treated with triple therapy (pantoprazole+amoxicillin+metronidazole). Subsequently, the patients were divided into two groups (group 1 – success, and group 2 – failure of eradication after therapy) and genotyped for the presence of CYP2C19 variant alleles (*2, *3, and *17).ResultsFrequency of CYP2C19 alleles in two groups of patients were: 56.4 versus 65 (p=0.060) for *1, 15.4 versus 5.3 (p=0.015) for *2, and 28.2 versus 25.5 (p=0.663) for *17 allele, respectively. CYP2C19*3 was not detected in the evaluated population. No significant differences in frequency nor distribution of *17 allele were found between two groups of patients. CYP2C19*2 allele was associated with successful H. pylori eradication (p<0.02), *2 allele carriers were found to be over 4-times more prone to the treatment compared to *1/*1 homozygotes (OR=4.2, p=0.015).ConclusionOur results suggest that, contrary to CYP2C19*2, CYP2C19*17 allele has no impact on efficacy of H. pylori eradication in peptic ulcer patients treated with pantoprazole.

The expansion of CD4+CD28- T cells in patients with rheumatoid arthritis.

Clonal expansion of CD4+CD28- T cells is a characteristic finding in patients with rheumatoid arthritis (RA). Expanded CD4+ clonotypes are present in the peripheral blood, infiltrate into the joints, and persist for years. CD4+CD28- T cells are oligoclonal lymphocytes that are rare in healthy individuals but are found in high percentages in patients with chronic inflammatory diseases. The size of the peripheral blood CD4+CD28- T-cell compartment was determined in 42 patients with RA and 24 healthy subjects by two-color FACS analysis. The frequency of CD4+CD28- T cells was significantly higher in RA patients than in healthy subjects. Additionally, the number of these cells was significantly higher in patients with extra-articular manifestations and advanced joint destruction than in patients with limited joint manifestations. The results suggest that the frequency of CD4+CD28- T cells may be a marker correlating with extra-articular manifestations and joint involvement.

The effect of monoamine oxidase B (MAOB) and catechol-O-methyltransferase (COMT) polymorphisms on levodopa therapy in patients with sporadic Parkinson's disease

Objectives –  The etiology of sporadic idiopathic Parkinsons disease (PD) is considered multifactorial with both genetic and environmental factors modifying the disease expression. Recent studies suggest that polymorphism in monoamine oxidase B (MAOB) and catechol‐O‐methyltransferase (COMT) might influence the risk and treatment of PD. The aim of the study was to evaluate the effect of MAOB and COMT genetic polymorphism on effective daily dose of levodopa applied during the first 5 years of treatment, and to find out if a relationship exists between MAOB and COMT haplotypes and motor disturbances onset in PD patients treated with levodopa preparations.

Frequency distribution of thiopurine S-methyltransferase alleles in a Polish population

Thiopurine S-methyltransferase (TPMT) is an enzyme that catalyzes the S-methylation of thiopurine drugs such as 6-mercaptopurine, 6-thioguanine, and azathioprine. TPMT activity exhibits an interindividual variability mainly a result of genetic polymorphism. Patients with intermediate or deficient TPMT activity are at risk for toxicity after receiving standard doses of thiopurine drugs. It has previously been reported that 3 variant alleles:TPMT*2, *3A, and *3C are responsible for over 95% cases of lower enzyme activity. The purpose of this study was to determine the frequency of TPMT variant alleles in a Polish population. DNA samples were obtained from 358 unrelated healthy Polish subjects of white origin, and TPMT genetic polymorphism was determined using PCR-RFLP and allele-specific PCR methods. The results showed that allelic frequencies were 0.4% for TPMT*2, 2.7% for TPMT*3A, and 0.1% for TPMT*3C, respectively. A TPMT*3B allele was not found in the studied population. The general pattern of TPMT allele disposition in the Polish population is similar to those determined for other white populations, but the frequency of total variant alleles is lower than in other European populations studied to date.

The impact of thiopurine S-methyltransferase polymorphism on azathioprine-induced myelotoxicity in renal transplant recipients

Thiopurine S-methyltransferase (TPMT) is an enzyme that catalyzes the S-methylation of thiopurine drugs such as 6-mercaptopurine, 6-thioguanine, and azathioprine. TPMT activity exhibits an interindividual variability, mainly as a result of genetic polymorphism. Patients with intermediate or deficient TMPT activity are at risk for toxicity after receiving standard doses of thiopurine drugs. It has previously been reported that 3 variant alleles: TPMT*2, *3A, and *3C are responsible for over 95% cases of low enzyme activity. The purpose of this study was to explore the association between these polymorphisms and the occurrence of azathioprine adverse effects in 112 renal transplant recipients undergoing triple immunosuppressive therapy including azathioprine, cyclosporine, and prednisone. TPMT genetic polymorphism was determined using PCR-RFLP and allele-specific PCR methods. Azathioprine dose, leukocyte, erythrocyte, and platelet counts, graft rejection episodes, as well as cyclosporine levels were analyzed throughout the first year after organ transplantation. We found the frequency of leukopenia episodes (WBC < 4.0 × 109/L) significantly higher in heterozygous patients (53.8%) compared with those with TPMT wild-type genotype (23.5%). One patient, who was a compound homozygote (3A/*3C), experienced severe azathioprine-related myelotoxicity each time after receiving the standard drug dose. Our results suggest that polymorphisms in TPMT gene may be responsible for approximately 12.5% of all leukopenia episodes in renal transplant recipients treated with azathioprine. Genotyping for the major TPMT variant alleles may be a valuable tool in preventing AZA toxicity and optimization of immunosuppressive therapy.

Effect of CYP2C19 and MDR1 polymorphisms on cure rate in patients with acid-related disorders with Helicobacter pylori infection

A proton pump inhibitor (PPI) plus two antibiotics (amoxicillin and either clarithromycin or metronidazole) are recommended for treatment of acid-related disorders with Helicobacter pylori (H. pylori) infection. The aim of this pharmacogenetic study was to evaluate the efficacy of triple therapy with PPIs on eradication of H. pylori infection in relation to cytochrome P450 2C19 (CYP2C19) and P-glycoprotein (MDR1) gene polymorphisms. The retrospective study involved 70 Polish Caucasian patients with H. pylori infection, diagnosed and treated with one of the two different triple therapy regimens [omeprazole, amoxicillin, and clarithromycin (OAC) or pantoprazole, amoxicillin, and metronidazole (PAM)]. Using genomic DNA, CYP2C19 (*2 and *3) and C3435T MDR1 alleles were determined by means of polymerase chain reaction-restriction fragment length polymorphism assays. A significantly higher prevalence (P<0.05) of heterozygous extensive metabolizers (hetEM) with CYP2C19*1/*2 genotype (32.4% versus 8.3%) and homozygous with 3435TT MDR1 genotype (38.2% versus 13.9%) was found in patients cured after the first cycle of triple therapy than in patients with failure of eradication after the first cycle. CYP2C19*1/*2 and 3435TTMDR1 genotypes as well as PAM regimen of treatment were also predictive of successful eradication of H. pylori infection after the first cycle of triple therapy at univariate/multivariate logistic regression analysis. This pharmacogenetic study on the influence of different CYP2C19 and C3435TMDR1 genotypes on H. pylori eradication suggests that CYP2C19 and MDR1 polymorphisms may be independent predictable determinants of the efficacy of triple therapy including PPI. The PAM regimen of treatment seems to be more effective after the first cycle of the therapy than the OAC regimen.

The −590 IL-4 promoter polymorphism in patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease in which cytokines play an important role. The aim of the present study was to evaluate the −590 IL-4 promoter polymorphism in patients with RA and its association with disease activity and severity. We enrolled 94 patients with RA diagnosed according to the criteria of the American College of Rheumatology. Polymerase chain reaction amplification was used for analysis of the polymorphism at position −590 of the promoter of the IL-4 gene. The distribution of IL-4 genotypes in RA patients did not differ from control subjects. Nevertheless, the active form of RA was more frequently diagnosed in patients with T allele (genotypes CT and TT) as compared with homozygous CC patients. Moreover, in carriers of the T allele, parameters of disease activity (DAS 28 score, ESR, number of swollen and tender joints) were significantly increased. We suggest that the IL-4 −590 promoter polymorphism may be a genetic risk factor for RA severity.

Involvement of P‐glycoprotein in the release of cytokines from peripheral blood mononuclear cells treated with methotrexate and dexamethasone

P‐glycoprotein (P‐gp), a product of the MDR1 gene, is an important factor in the turnover of many drugs and xenobiotics. Recent reports have suggested that P‐gp can also be involved in the transport of cytokines. The aim of this study was to examine the role of P‐gp in cytokine release from phytohaemagglutinin (PHA)‐stimulated peripheral blood mononuclear cells (MNCs) as well as in the release of cytokines from MNCs treated with methotrexate (MTX) and dexamethasone (DEX). The study was carried out on PHA‐stimulated MNC from 10 healthy subjects. Flow cytometry was applied to measure interleukin (IL)‐2, IL‐4, IL‐6, IL‐10, interferon (IFN)‐γ and tumour necrosis factor (TNF)‐α levels in the culture supernatants. In the experiments verapamil (VER) and P‐gp specific monoclonal antibodies (mAb) (clone 17F9) were used to inhibit P‐gp function. P‐gp inhibitors suppressed the release of IL‐2, IL‐4, IFN‐γ and TNF‐α from PHA‐stimulated MNC, whereas release of IL‐6 and IL‐10 remained unaffected. VER and mAb significantly decreased the release of IL‐2, IL‐4, TNF‐α and INF‐γ in MNC cultures treated with MTX or DEX. The results of this study suggest that P‐gp may be involved in the transmembrane transport of some cytokines. Moreover, it seems that blocking of P‐gp function may influence the release of some cytokines from MNCs, displaying an additive inhibitory effect to DEX and MTX.

Polymorphism of GSTM1 gene in patients with colorectal cancer and colonic polyps.

The frequency of the GSTM1 gene in patients with nonpolyposis colorectal cancer (CRC) (n = 70) and in subjects with colonic polyps (n = 27) was evaluated and compared with healthy individuals (n = 145). Patients with CRC were divided into the three groups: patients coming from the families with hereditary nonpolyposis colorectal cancer (HNPCC) (n = 17); patients with a high risk of HNPCC who were referred to as suspected of HNPCC (n = 25); patients with sporadic colorectal cancer without clinical features of hereditary tumours (n = 28). A simple polymerase chain reaction (PCR) - based assay to identify GSTM1 nulled and positive (non-nulled) genotype was used. No significant differences in frequency of nulled individuals were observed in both patients with HNPCC and patients suspected of HNPCC as well as in subjects with colonic polyps. The most interesting observation was made in the group of patients with sporadic CRC. Twenty individuals (71.4 %) of the group were GSTM 1 deficient which was significantly different from the control population (p < 0.04). The above data indicate that the absence of the GSTM1 gene is associated with a greater risk of sporadic colorectal cancer. There is an increase in the overall risk of approximately 2.5 as compared with the control population.

Studies on the Pharmacokinetics and Pharmacodynamics of Propranolol in Hyperlipidemia

The lipophilic beta‐adrenoreceptor antagonist propranolol has been studied to define its pharmacokinetic and pharmacodynamic characteristics in hyperlipidemic patients. A total of 48 subjects were allocated to four study groups: (1) healthy volunteers, (2) hypercholesterolemic patients, (3) hypertriglyceridemic subjects, and (4) patients with a mixed form of hyperlipidemia. Propranolol was given orally as a single dose of 80 mg. Heart rate was measured during 12 hours. At each point, the concentrations of propranolol were estimated. Moreover, heart rate and arterial systolic blood pressure were examined at rest and after a submaximal exercise test 3 hours after administration of propranolol (i.e., at the peak of propranolol concentration in the blood serum). A significant increase in the area under the serum concentration‐time curve (AUC) by 39% and a reduction of the volume of distribution and total body clearance by 48% and 46%, respectively, without a significant change in the half‐life time, were observed in patients with hypertriglyceridemia in comparison with the control group. The acceleration of exercise heart rate and the elevation of systolic blood pressure were comparable in all groups in the study, whereas blood serum concentrations of propranolol in patients with hypertriglyceridemia (group 3) and the mixed form of hyperlipidemia (group 4) were markedly altered from those observed in normolipemic subjects. No relationship between the concentration of propranolol and the heart rate in the group with hypertriglyceridemia was seen. In the light of this study, the authors suggest that lipid metabolism disturbances do not affect the pharmacodynamics of propranolol.