Natural evolution of hepatitis C virus infection in hemodialysis Tunisian patients and CTLA-4 SNP's.

AIM: To analyze the polymorphisms of CTLA-4 gene involved in the response against hepatitis C virus (HCV) infection. METHODS: We recruited 500 hemodialysed patients from several hemodialysis centers, all HCV-antibody positive, spread over different regions of Tunisia, as part of a national survey in 2008 conducted in the laboratory of immunology at the Charles Nicolle hospital Tunisia, classified into two groups G1 (PCR+) and G2 (PCR-) according to the presence or absence of viral RNA. Of these patients, 307 were followed prospectively on a viral molecular level over a period from 2002 to 2008, divided into two groups based on the persistence and viral clearance. PCR-RFLP was performed for the analysis of SNPs (+49) A/G and (+6230) G/A CTLA-4 for these 500 patients and 358 healthy controls. RESULTS: Analysis of clinical and virological characteristics of our cohort suggests a nosocomial infection in our hemodialysed patients with transfusion history as a primary risk factor and a predominance of genotype 1b. The haplotype analysis revealed an increase of frequencies of GG (+49)/(CT60) CTLA-4 in the entire patients group compared to controls (P = 0.0036 and OR = 1.42; 95%CI: 1.12-1.79, respectively). This haplotype is therefore associated with susceptibility to HCV infection. CONCLUSION: Our study suggests a possible role of CTLA-4 polymorphisms in the outcome of HCV infection in the Tunisian hemodialysed population.

Vascular endothelial growth factor genetic polymorphisms and susceptibility to age-related macular degeneration in Tunisian population.

PURPOSE: Three VEGF SNPs (-2578) C/A, (+405) G/C and (+936) C/T were investigated in Tunisian exudative AMD patients in order to determine their association with the disease susceptibility and their influence to intravitreal bevacizumab therapy response. METHODS: 145 AMD patients and 207 age-matched controls were included. 68 patients were treated with intravitreal bevacizumab. SNPs genotyping were performed using direct sequencing. The serum VEGF was assayed by ELISA (R&D). RESULTS: The (+405) CC and (+936) TT genotypes were higher in AMD patients than in controls (p = 5 × 10(-6) and p = 0.021, respectively). The mean plasma levels of VEGF were statistically higher in AMD patients (84.22 pg/ml) than in controls (15 pg/ml). Three months after bevacizumab treatment, 52 patients (85.6%) were classified as good responders (GR) and 16 (14.4%) as poor responders (PR). The mean plasmatic-VEGF levels in GR patients was higher (86.61 ± 80.30 pg/ml) than in PR patients (47.12 ± 45.74 pg/ml) (p = 0.086). The patients with genotype homozygous TT (+936) would be PR compared to those carrying CT and CC genotypes. Whereas, those with AA (-2578) genotype would be GR compared with others genotypes (p = 0.014; p = 0.042 respectively). CONCLUSIONS: Our results show that VEGF genetic variants may contribute to the susceptibility to neovascular AMD in Tunisian patients.

Cytokine and apoptosis gene polymorphisms influence the outcome of hepatitis C virus infection.

BACKGROUND: Hepatitis C virus (HCV) infection is thought to be chronic and the factors leading to viral clearance or persistence are poorly understood. This study was undertaken to investigate the possibility of a significant relationship between the spontaneous clearance or the persistence of hepatitis C virus (HCV) infection and cytokine and apoptosis gene polymorphisms in Tunisian patients on hemodialysis. METHODS: Polymorphisms of the genes IL-1 (-889 IL-1alpha, -511 and +3954 IL-1beta, IL-1Ra), IL-18 (-137 and -607), IL-12 (-1188) and Apo1/Fas (-670) were determined by PCR-RFLP, PCR-SSP and PCR-VNTR in 100 healthy blood donors and 100 patients infected with HCV and undergoing hemodialysis. The patients were classified into two groups: G1 consisted of 76 active chronic hepatitis patients (positive for HCV RNA) and G2 consisted of 24 hemodialysed patients who spontaneously eliminated the virus (negative for HCV RNA). RESULTS: The frequency of genotype association [-137GC/-607CA] IL-18 was higher in G2 (41.7%) than in G1 (15.8%) (P=0.008; OR=0.26; 95% CI, 0.10-0.73). We also found a higher frequency of the AA genotype of the Apo1/Fas gene in G2 (41.6%) than in G1 (17.5%) (P=0.026; OR=3.49; 95% CI, 1.13-10.69). Adjustment for known covariate factors (age, gender and genotype) confirmed these univariate findings and revealed that the genotype association GC-CA of the (-137 and -607) IL-18 gene and the AA genotype of the Apo1/Fas gene were associated with the clearance of HCV (P=0.041 and 0.017, respectively). CONCLUSION: The two genotypes GC-CA of the (-137 and -607) IL-18 polymorphism and the AA genotype of the Apo1/Fas gene influence the outcome of HCV infection in Tunisian patients on hemodialysis.

CD86 +1057G>A polymorphism and susceptibility to acute kidney allograft rejection.

INTRODUCTION: CD86 is a costimulatory molecule that participates in the regulation of T-cell lymphocytes activation. Thus, we examined a genetic marker on the CD86 gene in kidney transplant outcome. MATERIALS AND METHODS: In our retrospective study, 168 kidney allograft recipients were genotyped by direct sequencing. Patients were classified into 2 groups of 29 human leukocyte antigen (HLA)-identical haplotype allograft recipients and 139 recipients showing one or more mismatches in the HLA haplotype. Forty-five patients (26.8%) developed at least 1 acute rejection (AR) episode, 7 in the first and 38 in the second group. RESULTS: Acute rejection was associated with the presence anti-HLA antibodies before transplantation (P = .03). The AA genotype and A allele at position +1057 in the CD86 gene were more frequent in patients without AR (9.75% and 28.5%, respectively) compared with those showing an AR (2.22% and 23.3%, respectively). This difference was statistically significant in the anti-HLA-positive recipients, as AA frequency was 31.3% in non-AR patients and zero in AR ones (P = .04) and A allele frequency was 46.9% and 20.8%, respectively (P = .04). Patients bearing AA genotype reached a higher graft survival time (9.84 years) than those carrying GA (8.21 years, P = .32) or GG (7.61 years, P = .72) genotypes. CONCLUSIONS: These results suggest that AA genotype and A allele of CD86 +1057G>A polymorphism may confer a protection against acute kidney allograft rejection in Tunisian patients.

[IL1/IL1 Ra, CTLA-4 and Apo1/Fas genes polymorphisms and susceptibility to IgA nephropathy in Tunisian patients]. / Polymorphismes des gènes de l'IL1/IL1 Ra, CTLA-4 et Apo1/Fas et susceptibilité à la néphropathie à IgA chez des patients Tunisiens.

BACKGROUND: The IgA nephropathy (IgA-N) is considered the most common form of primary glomerulonephritis and its pathogenic mechanisms are very complex. The study of several genes which encode for immunoregulator molecules in inflammatory and immunological responses during the disease, allowed to describe some number of polymorphisms would be involved in the molecular expression, the road marking, the synthesis and\or the binding to the receptors. So an abnormality of the molecular function associated with its polymorphism would be suggested in the genetic predisposition to the disease. AIM: To determine interleukin 1 (IL1), interleukin1 receptor antagonist (IL1 Ra), CTLA-4 and Apo1/Fas genes polymorphisms frequencies in IgA-N in order to estimate the impact of these polymorphisms in the disease susceptibility. METHODS: The polymorphism of a single nucleotide (SNP) at (-889) IL1 a of 21 IgA-N patients and 100 healthy blood donors, as controls, was studied by PCRSSP. The SNPs of the IL1 ß (+3954), CTLA-4 (+49) and l'Apo1/Fas were analyzed by PCR RFLP and finally the polymorphism of the IL1 Ra gene was determined by a PCR VNTR (variable number tandem repeat). RESULTS: Investigation of IL1a/ß and Apo1/Fas polymorphisms showed no differences in genotypes and alleles frequencies between IgA-N patients and controls. However, genotype AA of CTLA-4 exon1 (+49) was significantly higher in patients (47.62%) than in controls (9.1%) p<0.001. Nevertheless, the clinical, histological and biological characteristics of IgA-N were similar in AA CTLA-4 genotype patients compared to AG or GG genotype patients. We fund also, a significant increased frequency of 1/1 IL1 Ra genotype in IgA-N patients (95.24%) compared to controls (54%) (p<0.001) (p<0.001). CONCLUSION: We conclude that the susceptibility to IgA-N seems to be associated with the presence of CTLA-4 AA and IL1 Ra 1/1 genotypes in Tunisian population. However, the lack of association between IL1 a/ß and Apo1/fas genes polymorphisms should be further investigated by large population based studies.

Role of genetic polymorphisms in factor H and MBL genes in Tunisian patients with immunoglobulin A nephropathy.

The molecular mechanisms of IgA nephropathy (IgAN) remain poorly understood. Several different polymorphic genes have been investigated in order to demonstrate their possible association with this disease. It is evident that mainly alternative and lectin pathways complement activation and play an important role in renal injury of IgAN. This study was conducted to determine eventual deficiencies of factor H in the SCR20 gene region and to look for a possible association between the polymorphism (+54) exon 1 of the MBL gene and the predisposition in Tunisian patients with IgAN. We then evaluated the effects of these FH mutations and/or this MBL polymorphism on nephropathy susceptibility and progression. Polymorphism A/B (+54) in the exon1 of the MBL gene and analysis within the C-terminal domain of the protein SCR20 in the exon 22 of the factor H (FH) gene were conducted in 36 sporadic IgAN Tunisian patients and 117 age and gender matched healthy subjects recruited from blood donors, by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and direct sequencing respectively. The analysis of the Gly54Asp (+54) mutation of the MBL gene according to the criteria of gravity of the IgAN reveals that the patients with genotype AB present more frequently with end-stage renal disease (ESRD) compared with those of genotype AA [OR: 8, CI (1.74-54.49), P = 0.019]. Moreover, the variant allele B was statistically more frequent than the allele A in patients with an association with initial arterial high blood pressure, ESRD and class V of the Haas classification compared to those without this association (P = 0.009). The direct sequencing of exon 22 (SCR 20) of FH gene did not reveal any abnormal mutational deficiency for this factor in all patients and controls. The data did not support the hypothesis that FH is a susceptibility factor for the IgAN. However the data did show there was an association between AB (+54) exon1 MBL genotype and severe sporadic forms of this disease in Tunisian patients. Because of the small number of subjects studied, a much larger cohort of IgAN patients with varying severity of the disease and its progression would seem necessary to confirm these findings.

Role of immune system, apoptosis and angiogenesis in pathogenesis of rheumatoid arthritis and joint destruction, a systematic review.

BACKGROUND: Rheumatoid arthritis (RA) is a chronic inflammatory disorder of unknown cause that is notorious for the chronic polyarticular synovial inflammation and progressive destruction of affected joints. Understanding the pathogenesis of RA provides the basis for optimal management of that disease in patients. The pathogenesis of RA was largely explored in many studies in human as much as in mice models with collagen II induced arthritis, nevertheless the pathogenesis puzzle is still incomplete. AIM: The aim of this systematic review was to collect the results of many observations and to put them down into an original story of RA set up. METHODS: An exhaustive electronic and library search of the relevant literature was carried out through "science direct" and "interscience wiley" web sites. The key words used for the search were "rheumatoid arthritis", "pathogenesis", "apoptosis", "angiogenesis", "immune response" and "joint destruction". RESULTS: The suspected responsible antigen isn't yet determined although the great specificity of anti-CCP antibodies suggests that this antigen carries probably many citrullinated residues. The immuno-pathogenesis of RA involves both the innate and the adaptive immune system. In the other hand, apoptosis defect contribute to hyperplasia of rheumatoid synovium and in extended half life of fibroblast like synoviocytes (FLS), neutrophils and many other cells implied in rheumatoid synovitis. Hyperplasia of synovium leads to ischemia and that results in neo-angiogenesis with increase of proangiogenic factors such as VEGF. The last part of the pathogenesis of RA is the joint destruction resulting from increased MMP production and activation of osteoclasts which leads to the breakup of cartilage and to bone damage.