Evaluation of X chromosome inactivation in endemic Tunisian pemphigus foliaceus

BACKGROUND

Almost 5% of the world's population develops an autoimmune disease (AID), it is considered the fourth leading cause of disability for women, who represent 78% of cases. The sex ratio when it comes to the most prevalent AID varies from 9:1 in systemic lupus erythematosus (SLE) to 13:1 in endemic Tunisian pemphigus foliaceus (PF).

METHODS

To test the potential involvement of skewed x-inactivation in the pathogenesis of Tunisian PF, we analyzed the methylation status of a highly polymorphic CAG repeat in the androgen receptor gene and evaluated the x chromosome inactivation (XCI) patterns in peripheral blood-leukocyte-derived DNA samples of female patients with PF (n = 98) compared to healthy control (HC) subjects (n = 150), as well as female patients with SLE (n = 98) were enrolled as a reference group.

RESULTS

XCI status was informative for 50 of the 98 PF patients (51%) and 70 of the 150 HC women (47%). Extremely skewed XCI patterns were more frequent in PF and SLEwomen than HC, but the difference was statistically significant only in women with SLE. No statistical difference was observed in XCI patterns between PF and SLE patients. PF phenotype-XCI correlation analysis revealed that (i) skewed XCI patterns may be involved in the disease's subtype and (ii) it was more pronounced in the endemic group than the sporadic one. Furthermore, preferential XCI showed an increase in heterozygote genotypes of PF's susceptibility polymorphisms in immunity-related X genes (FOXP3, AR, and TLR7) in PF patients compared to HC.

CONCLUSION

Our results suggest that skewed XCI could lead to hemizygosity of X-linked alleles that might unmask X-linked deleterious alleles.

Role of innate immune receptors TLR4 and TLR2 polymorphisms in systemic lupus erythematosus susceptibility

AIM

Through their recognition of various bacterial cell wall components, TLR2 and TLR4 participate in the innate response and modulate the activation of adaptive immunity. Therefore, the genetic background of these receptors might play a crucial role in autoimmune diseases such as systemic lupus erythematosus (SLE). In this study, we investigated the possible association between polymorphisms within TLR2 and TLR4 genes with SLE susceptibility.

MATERIAL AND METHODS

A total of 100 SLE patients and 200 unrelated healthy controls of the Tunisian population were enrolled in the study.TLR4rs4986790, TLR4rs4986791, and TLR2rs5743708 genotyping were performed using a polymerase chain reaction-restriction fragment length polymorphism method. The number of guanine-thymine (GT) repeat microsatellite in the intron 2 of TLR2 gene was analyzed by sequencing.

RESULTS

We reported a lack of allelic and genotypic association between SNPs of TLR4 and TLR2 genes and SLE pathogenesis. No correlation was found with any SLE features. However, SLE susceptibility was associated with the GT repeat microsatellite polymorphism in the human TLR2 gene. Further subclassification of alleles into three subclasses revealed a significant association between the long-sized repeats ((GT) >23) and SLE.

CONCLUSION

Though the results showed the absence of genetic association of TLR4 and TLR2 SNPs with the risk of developing SLE, we have identified a protective association between the microsatellite polymorphism in intron 2 of the TLR2 gene and SLE. Functionally, these (GT)n repeats may confer modifying effects or susceptibility to certain inflammatory conditions.

Optical studies and dielectric response of [DMA]2MCl4 (M = Zn and Co) and [DMA]2ZnBr4

[DMA]₂ZnCl₄, [DMA]₂CoCl₄ and [DMA]₂ZnBr₄ crystallized in the monoclinic system, in the P2₁/n, P2₁/n and P2₁/c space groups, respectively. The optical properties of [DMA]₂MCl₄ (M = Zn and Co) and [DMA]₂ZnBr₄ were studied using ultraviolet-visible (UV-Vis) spectroscopy in the range of 200–800 nm. The Tauc model was used to determine the band gap energy of each hybrid compound. The calculated values of the direct and indirect band gaps (E_gd, E_gi) for all samples were found to be in the range of 1.91 eV to 4.29 eV for [DMA]₂ZnCl₄, 4.76 eV to 5.34 eV for [DMA]₂ZnBr₄ and 1.77 eV to 3.84 eV for [DMA]₂CoCl₄. The Urbach energy (E_u), extinction coefficient (k) and refractive index (n) of each compound was calculated. On the other hand, the dispersion of (n) is discussed in terms of the single oscillator Wemple–DiDomenico model. The single oscillator energy (E₀), the dispersion energy (E_d), and both the real ε_r and imaginary parts ε_i of the dielectric permittivity were estimated. The variation of optical conductivity with the incident photon energy has also been studied. We employed impedance spectroscopy to thoroughly investigate the dipolar dynamics in the prepared materials. The evolution of the dielectric loss, as a function of frequency, showed a distribution of relaxation times, which probably could be of a Maxwell–Wagner type interfacial polarization relaxation, possibly attributed to grain boundary effects or blocking at the contacts. In fact, the current work opens an efficient path to high quality organic–inorganic halide perovskites with good optical properties, which makes them suitable for application in nonlinear optoelectronic devices.

[DMA]₂ZnCl₄, [DMA]₂CoCl₄ and [DMA]₂ZnBr₄ crystallized in the monoclinic system, in the P2₁/n, P2₁/n and P2₁/c space groups, respectively.

Chromosome 2q33genetic polymorphisms in Tunisian endemic pemphigus foliaceus

Background

Several studies have suggested that polymorphisms within genes encoding T‐lymphocyte immune regulating molecules: CD28, CTLA‐4, and ICOS, may alter the signaling process and subsequently could be involved in susceptibility to a broad spectrum of autoimmune diseases.

Methods

This study aimed to replicate associations between common polymorphisms in the 2q33.2 cluster and susceptibility to pemphigus foliaceus (PF) in the Tunisian population. We investigated seven polymorphisms: rs3116496 and rs1879877 (CD28), rs231775, rs3087243, and (AT)_n repeat (CTLA4); rs11889031 and rs10932029 (ICOS) in a case–control study which enrolled 106 Tunisian PF patients and 205 matched healthy controls.

Results

We confirmed the associations with CTLA4((AT)₁₃, p = 0.00137, OR = 3.96 and (AT)₂₀, p = 0.008, OR = 5.22; respectively) and ICOS genes (rs10932029>CT, p = 0.034, OR = 2.12 and rs10932029>TT, p = 0.04 and OR = 0.41).

Conclusion

Our results indicate that susceptibility to PF is located in the proximal and the distal 3′ flanking region of the CTLA4/ICOS promoter. These findings may open avenues to the treatment of patients with biological drugs targeting CTLA4/ICOS molecules, in a personalized manner to achieve more effective treatment.

Association of HLA Alleles with Primary Sjögren Syndrome in the South Tunisian Population

OBJECTIVE

In order to investigate human leukocyte antigen (HLA) genes predisposing to primary Sjögren syndrome (pSS), we conducted an association study using HLA loci (A, B, and DRB1) and 9 polymorphic microsatellite markers spanning the HLA region in pSS patients as compared to healthy individuals.

SUBJECTS AND METHODS

Forty-four patients fitting the European criteria of pSS and 123 healthy controls were analyzed for their HLA class I and class II alleles. HLA class I typing was performed using a standard microlymphocytotoxicity method followed by PCR-SSP. HLA-DRB1 genotyping was performed using PCR-SSP. We studied the polymorphism of 9 microsatellite markers for both groups. Microsatellite genotyping was performed using the PCR fluorescent technique.

RESULTS

We observed a positive association between HLA-B15 and pSS in the Tunisian population (p = 0.004, OR 7.57). The comparison of the frequencies of DRB1 alleles in pSS patients and controls confirmed the association of the DRB1*03 allele with pSS (p = 0.02, OR 2.36). On the other hand, the association study of microsatellite markers showed that the a9 allele of D6S265 marker and the a20 of C1.2.C were found to be positively associated with pSS as compared to controls (p =0.0003, OR 10.29, and p =0.001, OR 4.79, respectively). Using the "Haplo.stats" software analysis, we found that the most associated region was located in the HLA class I region and limited by HLA-A and D6S265 loci (p = 0.00056).

CONCLUSION

The results of this study support the hypothesis of the existence of a susceptibility gene for pSS located in the HLA class I and III regions.

Analysis of two susceptibility SNPs in HLA region and evidence of interaction between rs6457617 in HLA-DQB1 and HLA-DRB1*04 locus on Tunisian rheumatoid arthritis

Previous genomewide association studies (GWAS) and meta-analyses have enumerated several genes/loci in major histocompatibility complex region, which are consistently associated with rheumatoid arthritis (RA) in different ethnic populations. Given the genetic heterogeneity of the disease, it is necessary to replicate these susceptibility loci in other populations. In this case, we investigate the analysis of two SNPs, rs13192471 and rs6457617, from the human leukocyte antigen (HLA) region with the risk of RA in Tunisian population. These SNPs were previously identified to have a strong RA association signal in several GWAS studies. A case-control sample composed of 142 RA patients and 123 healthy controls was analysed. Genotyping of rs13192471 and rs6457617 was carried out using real-time PCR methods by TaqMan allelic discrimination assay. A trend of significant association was found in rs6457617 TT genotype with susceptibility to RA (P = 0.04, pc = 0.08, OR = 1.73). Moreover, using multivariable analysis, the combination of rs6457617*TT-HLA-DRB1*04+ increased risk of RA (OR = 2.38), which suggest a gene-gene interaction event between rs6457617 located within the HLA-DQB1 and HLA-DRB1. Additionally, haplotypic analysis highlighted a significant association of rs6457617*T-HLA-DRB1*04+ haplotype with susceptibility to RA (P = 0.018, p_c = 0.036, OR = 1.72). An evidence of association was shown subsequently in antiCCP+ subgroup with rs6457617 both in T allele and TT genotype (P = 0.01, p_c = 0.03, OR = 1.66 and P = 0.008, p_c = 0.024, OR = 1.28, respectively). However, no association was shown for rs13192471 polymorphism with susceptibility and severity to RA. This study suggests the involvement of rs6457617 locus as risk variant for susceptibility/severity to RA in Tunisian population. Secondly, it highlights the gene-gene interaction between HLA-DQB1 and HLA-DRB1.

HLA Class III: A susceptibility region to systemic lupus erythematosus in Tunisian population

BACKGROUND AND OBJECTIVES

Short tandem repeats (STR) are usually used as informative polymorphic markers for genetic mapping and for disease susceptibility analysis. The involvement of these microsatellite markers localized in the MHC region was reported in many auto-immune diseases. In this study we analyzed for the first time eight polymorphisms of microsatellite loci at the HLA region: D6S291, D6S273, TNFa, b and c, MICA, D6S265 and D6S276, in Tunisian systemic lupus erythematosus (SLE) patients.

MATERIALS AND METHODS

We performed a case control study in which the microsatellite loci were amplified using specific primers labeled with NED, VIC, PET or 6-FAM and analyzed using GeneScan software 3.7. For the statistical analysis, we used SPSS software and we performed a sub-haplotype scoring test using the haplo.stats software developed in the R language.

RESULTS

We found that two mean associated regions existed; the most statistically significant encompassed the 3 TNF markers (p = 0.0003, OR = 19.34); the latter covered the DR region. In fact, when scoring haplotypes in 3 marker- sliding windows, the p value increased as we moved away from the TNF region and decreased again when we approached the DRB1 locus. We also established for the first time the negative association between alleles of D6S291 and SLE. The majority of clinical and serological correlations were noted with TNF alleles.

CONCLUSION

Our results confirm the association between TNF and DRB1 polymorphisms and SLE. The association between alleles of D6S291 and SLE needs however to be verified by the analysis of other markers beyond this region.

Human leukocyte antigens-DRB1*03 is associated with systemic lupus erythematosus and anti-SSB production in South Tunisia

INTRODUCTION

Systemic lupus erythematosus (SLE) is an autoimmune disease with various presentations. This variation is due to the interaction of hormonal, environmental, and genetic factors. Associations between human leukocyte antigens and SLE have long been recognized in different ethnic populations and have been suggested to represent the most important association.

OBJECTIVES

The objectives of this paper were to determine susceptibility and protection human leukocyte antigens (HLA) Class II markers for SLE and to highlight, for the first time, associations between HLA alleles and clinical and serological features in South Tunisia.

METHODS

We conducted a case-control study on 75 SLE patients and 123 healthy controls. The HLA Class II DRB1/DQB1 of all patients and controls was genotyped using polymerase chain reaction-sequence specific primer technique. Statistical analysis was performed using SPSS software.

RESULTS

HLA-DRB1*03 was the principal Class II allele associated with the genetic susceptibility to SLE (pc = 0.02; OR = 2.57; CI = [1.39-4.75]; this allele was also associated with anti-SSB production (P = 0.016; OR = 4.00; CI = [1.24-12.96]). HLA-DRB1*01 was significantly more expressed in SLE patients with neurologic disorders (P = 0.013; OR = 20.25; CI = [1.87-219.21]). No allele was found to be protective against SLE in our study group.

CONCLUSION

Our results show that in South Tunisia SLE is associated with HLA-DRB1*03 and that some clinical features of SLE may be influenced by specific DRB1 and DQB1 alleles.

Measurement of absolute copy number variation of Glutathione S-Transferase M1 gene by digital droplet PCR and association analysis in Tunisian Rheumatoid Arthritis population

BACKGROUND

The investigation of copy number variations (CNVs) analysis of candidate genes is currently an important research area in modulating human diseases. We aimed to quantify CNVs in glutathione S-transferase M1 (GSTM1) gene and determine its genetic contribution in Tunisian rheumatoid arthritis (RA) and its subsets through an innovative technique for quantification.

METHODS

A total of 165 RA cases and 102 healthy controls were included in the study. Using a recently powerful approach of digital droplet PCR (ddPCR), we quantified GSTM1 gene to determine the presence of no, one, or multiple copy number (CN) at high levels of sensitivity and specificity. Odds ratio and Fisher exact test were performed to estimate the association risk for GSTM1CNVs in RA.

RESULTS

Copy number identified by ddPCR was 0, 1, and 2 copies per diploid genome. A high frequency of '0' copy was revealed with 54% in RA patients. The deletion ('0' copy) of GSTM1 was found to be a significant risk factor for anti-cyclic citrullinated peptide (anti-CCP) positive RA (OR=4.16, CI_95% =[1.17-14.7]). In addition, a lack of association was found when comparing between the CNVs of RA patients and those of controls.

CONCLUSION

This study highlights the powerful accuracy of ddPCR for the quantification of CNVs and suggests that the variation in the CN of GSTM1 is associated with anti-CCP positivity in RA. However, it does not indicate a specific role in the susceptibility to the disease in our Tunisian sample.

Novel cases of Tunisian patients with mutations in the gene encoding 17β-hydroxysteroid dehydrogenase type 3 and a founder effect

17β-Hydroxysteroid dehydrogenase type 3 (17β-HSD3) is expressed almost exclusively in the testis and converts Δ4-androstene-3,17-dione to testosterone. Mutations in the HSD17B3 gene causing 17β-HSD3 deficiency are responsible for a rare recessive form of 46, XY Disorders of Sex Development (46, XY DSD). We report novel cases of Tunisian patients with 17β-HSD3 deficiency due to previously reported mutations, i.e. p.C206X and p.G133R, as well as a case with the novel compound heterozygous mutations p.C206X and p.Q176P. Moreover, the previously reported polymorphism p.G289S was identified in a heterozygous state in combination with a novel non-coding variant c.54G>T, also in a heterozygous state, in a male patient presenting with micropenis and low testosterone levels. The identification of four different mutations in a cohort of eight patients confirms the generally observed genetic heterogeneity of 17β-HSD3 deficiency. Nevertheless, analysis of DNA from 272 randomly selected healthy controls from the same geographic area (region of Sfax) revealed a high carrier frequency for the p.C206X mutation of approximately 1 in 40. Genotype reconstruction of the affected pedigree members revealed that all p.C206X mutation carriers harbored the same haplotype, indicating inheritance of the mutation from a common ancestor. Thus, the identification of a founder effect and the elevated carrier frequency of the p.C206X mutation emphasize the importance to consider this mutation in the diagnosis and genetic counseling of affected 17β-HSD3 deficiency pedigrees in Tunisia.

Beyond Human Leukocyte Antigen Class I Antigens: Hereditary Hemochromatosis Gene Mutations in Recurrent Aphthous Oral Ulcers and Behçet Disease in the South of Tunisia

OBJECTIVE

The aim of this work was to establish human leukocyte antigen (HLA) class I and hereditary hemochromatosis gene (HFE) mutation associations with recurrent aphthous oral ulcers (RAOU) and Behçet disease (BD) in a cohort of Southern Tunisian patients.

SUBJECTS AND METHODS

A total of 232 patients with RAOU and 123 healthy controls (HCs) were enrolled in this study. The patients were divided into 2 groups based on the presence (BD+: n = 62) or absence of BD (BD-, n = 170). In the BD+ group, 28 patients had severe manifestations of BD. In the BD- group, RAOU was isolated in 81 patients, associated with mucocutaneous manifestations in 58 and with joint symptoms in 25. Complement-dependent microlymphocytotoxicity assay and polymerase chain reaction-restriction fragment length polymorphism were used to study HLA class I polymorphism and HFE mutations, respectively.

RESULTS

HLA-B51 was positively associated with BD, particularly in those with severe manifestations. No association was detected with HLA class I polymorphism among the BD group. Based on stratification to clinical manifestations, the isolated RAOU was negatively associated with HLA-A1 with a difference close to significance (12 [14.81%] vs. 32 [26.02%] in HCs; p = 0.06). Furthermore, patients with mucocutaneous features had a higher frequency of HLA-B51 (14, 24.14%) than patients without mucocutaneous involvement (11, 11.37%). Considering HFE mutations, patients with isolated RAOU had a higher frequency of H63D when compared with other subgroups, especially after limiting the comparison to 27 patients of at least 5 years of follow-up.

CONCLUSION

This study showed that, unlike BD, RAOU were not associated with HLA-B51. Moreover, we suggest that H63D mutation was positively associated with isolated RAOU.

Genetic diversity and haplotype structure of 21 Y-STRs, including nine noncore loci, in South Tunisian Population: Forensic relevance

Y chromosome STRs (Y-STRs) are being used frequently in forensic laboratories. Previous studies of Y-STR polymorphisms in different groups of the Tunisian population identified low levels of diversity and discrimination capacity (DC) using various commercial marker sets. This definitely limits the use of such systems for Y-STRs genotyping in Tunisia. In our investigation on South Tunisia, 200 unrelated males were typed for the 12 conventional Y-STRs included in the PowerPlex® Y System. Additional set of nine noncore Y-STRs including DYS446, DYS456, DYS458, DYS388, DYS444, DYS445, DYS449, DYS710, and DYS464 markers were genotyped and evaluated for their potential in improving DC. Allele frequency, gene diversity, haplotype diversity (HD), and DC calculation revealed that DYS464 was the most diverse marker followed by DYS710 and DYS449 markers. The standard panel of 12 Y-STRs (DC = 80.5%) and the nine markers were combined to obtain DC of 99%. Among the 198 different haplotypes observed, 196 haplotypes were unique (HD = 99.999). Out of the nine noncore set, six Y-STRs (DYS458, DYS456, DYS449, DYS710, DYS444, and DYS464) had the greatest impact on enhancing DC. Our data provided putative Y-STRs combination to be used for genetic and forensic applications.

A hyaluronic acid–pentamidine bioconjugate as a macrophage mediated drug targeting delivery system for the treatment of leishmaniasis

A new HA–Pent bioconjugate was synthetized and proposed as drug targeting delivery system for the treatment of leishmaniasis, exploiting the specific biological recognition of HA by the macrophage.

Association study of MICA gene polymorphisms with rheumatoid arthritis susceptibility in south Tunisian population

The aim of this study was to investigate the role of major histocompatibility complex (MHC) class I chain-related gene A (MICA) polymorphisms, important in natural killer (NK) cell function, in patients with rheumatoid arthritis (RA). A transmembrane (TM) alanine-encoding GCT repeats, termed A4, A5, A5.1, A6 and A9 in the MICA gene, and single-nucleotide polymorphisms (SNPs): the Met129Val polymorphism (rs1051792) and the nonsynonymously coding SNP (rs1051794) were genotyped in 142 patients with RA and 123 unrelated healthy individuals using, respectively, PCR fluorescent method, nested PCR-RFLP and allele specific PCR (ASP). Association was assessed based on the χ2 test, genotype relative risk (GRR) and odds ratio (OR) with 95% confidence intervals (CIs). Our results show a trend of association of the different MICA genotypes G/G, G/A and A/A (P = 0.029) which did not attain the significance after Bonferroni's correction (pc = 0.08). Although, we revealed a significant association of the genotype A/A of MICA-250 in patients with RA compared to healthy controls (pc = 0.033). In contrast, no significant differences between alleles and genotypes frequencies were found either with MICA-TM or MICA met129 val (P > 0.05) in our sample. Moreover, stratification of patients with RA according to clinical and immunological data for the different polymorphisms studied shows a significant association of both MICA-250 G allele (pc = 0.0075) and MICA-250 GG genotype (pc = 0.008) and both allelic (val) (pc = 0.021) and genotypic (val/val) distribution (pc = 0.0095) for MICA met129 val in the RF-positive subgroup compared to RF-negative patients with RA. In contrast, we found a strong association of the MICA-TM A9 allele in RF-negative patients with RA (pc = 0.0003). This study indicates the involvement of the MICA-250 polymorphism in the genetic susceptibility and severity to RA and suggests that variations in MICA-TM and MICA met129 val may have an effect on RA severity in our south Tunisian sample.

Association study of MICA-TM polymorphism with inflammatory bowel disease in the South Tunisian population

BACKGROUND

Crohn's disease (CD) and ulcerative colitis (UC) are chronic inflammatory disorders of the gastro-intestinal tract with unknown etiology. Both environmental and genetic factors are involved in the pathogenesis of these inflammatory bowel diseases (IBD).

AIM

The purpose of the present study was to determine the association between the polymorphism of the transmembrane region of MICA (MICA-TM), and the genetic susceptibility in Tunisian patients with IBD.

PATIENTS AND METHODS

A total of 102 Tunisian patients (66 with UC, 36 with CD) and 123 healthy controls were enrolled in our study. MICA-TM was genotyped by a semiautomatic fluorescent-labelled PCR method, amplicons were analysed on an ABI Prism 310 genotyper. Comparisons of allele frequencies between patients and controls, and between patients' subgroups were performed using SPSS 13.0.

RESULTS

No MICA allele was significantly increased in both groups of IBD compared to controls. The MICA-A5.1 allele was significantly decreased in CD patients (p=0.006, pc=0.03). In UC, MICA-A6 was associated with the presence of extraintestinal manifestations (p=0.04, pc=0.2), whereas MICA-A5 was associated with late age of onset (p=0.04). In CD, MICA-A6 was significantly increased in active disease patients when compared to moderately active or inactive disease (p=0.03, pc=0.15).

CONCLUSION

Some clinical features of CD and UC may be influenced by specific MICA-TM alleles. In our South Tunisian population, MICA plays a disease modifying role, rather than being an important gene in the susceptibility for developing IBD.

A comparison of capillary electrophoresis and direct sequencing in upstream conserved sequence region analysis of Pneumocystis jirovecii strains

The major surface glycoprotein (MSG) of Pneumocystis jirovecii is the most abundant surface protein and appears to play a critical role in the pathogenesis of pneumocystosis. The expressed MSG gene is located immediately downstream of a region called the upstream conserved sequence (UCS). The UCS contains a region of tandem repeats that vary in number and sequence. In the present study, we have used capillary electrophoresis and direct sequencing to detect the variability in the repeat units of UCS. By direct sequencing the PCR products from samples of 13 patients, we have identified three types of repeat units which consisted of 10 nt and three different patterns in the UCS region with three and four repeats: 1, 2, 3 (84.6 %); 1, 2, 3, 3 (8.2 %); and a new genotype 2, 2, 3, 3 (8.2 %). The same samples were analysed by capillary electrophoresis. Three samples (23 %) contained a mixture of two or three different patterns of UCS repeats. In conclusion, quantifying the number of repeat units in the UCS by capillary electrophoresis provides a potential new method for the rapid typing of P. jirovecii and the detection of mixed infection.

Analysis of HLA-A, -B, -C, -DR, -DQ polymorphisms in the South Tunisian population and a comparison with other populations

BACKGROUND

The Human Leucocyte Antigen (HLA) system is often used as a genetic marker for analysing populations. HLA antigen distribution among the Tunisian population is not well defined because of the lack of a general population study.

AIM

The aim of the present study was to investigate the polymorphism of HLA-A, -B, -C, -DR and -DQ loci in the South Tunisian population.

SUBJECTS AND METHODS

This study has investigated HLA-A, -B, -C, -DR and -DQ polymorphisms in 123 unrelated healthy individuals originating from the south of Tunisia. HLA class I was studied by serology and completed by polymerase chain reaction-sequence specific primer (PCR-SSP). HLA class II was performed using PCR-SSP.

RESULTS

The most common alleles were A-2 (0.2154), B-44 (0.1179), C7 (0.2114), DR4 (0.1626) and DQ2 (0.313). A1-B-8-C7-DR3-DQ2 (2.84%) was the predominant haplotype in this population. Comparisons with data of other worldwide populations based on phylogenetic tree and multidimensional scaling analysis were done. This study suggests that both HLA class I and class II polymorphism specificities demonstrate a high diversity in this South Tunisian population, which reflects ancient and recent admixture with neighbouring populations.

CONCLUSION

The results provide useful information for further studies of Tunisian population evolution, anthropology and for resolving HLA frequencies when searching for HLA-compatible donors in transplantation and for the analysis of disease associations.

Microsatellite analysis of Candida isolates from recurrent vulvovaginal candidiasis

Candida albicans and Candida glabrata are the most common causative agents of both vulvovaginal candidiasis (VVC) and recurrent vulvovaginal candidiasis (RVVC). Studying the population structure and genotype differentiation of Candida species that cause RVVC may lead to a significant improvement in clinical management. A total of 106 isolates were collected from 55 patients who were subdivided into three groups. Group I comprised 15 patients with RVVC (n=50 isolates); group II comprised 16 patients, who had a history of at least two episodes of VVC in the last year (n=32 isolates, two from each patient); and group III comprised 24 patients (n=24 isolates) who had experienced a single episode of VVC in the previous 1 year period. C. albicans microsatellite markers CAI, CAIII and CAIV and C. glabrata RPM2, MTI and ERG3 microsatellites were amplified in a multiplex PCR. All isolates were subjected to population genetic analysis, which provided evidence that there is a predominantly clonal population structure of C. albicans in each group. However, recombination was detected to some degree in C. albicans isolates in group III. A genetic homogeneity between the different C. albicans groups was observed. Although, C. glabrata isolates showed an important genetic differentiation between group I and group III (F(ST)=0.207). Genotype analysis revealed that the dominant genotypes of C. glabrata and C. albicans strains were more prevalent in patients with RVVC. The frequent scenario for cases of recurrent infection in our study was strain replacement (53.3%). In conclusion, the identification of recurrence-associated genotypes and a specific C. glabrata population structure in the RVVC group could be a significant marker for further investigations of virulence factors and RVVC management.

Association study of human leukocyte antigen-DRB1 alleles with rheumatoid arthritis in south Tunisian patients

The aim of this study is to explore relationship between HLA-DRB1 alleles and the susceptibility and clinical features of rheumatoid arthritis (RA) in the south Tunisian population. We studied 142 RA patients and 123 controls matched for age, sex, and ethnicity. HLA-DRB1 genotyping and HLA-DRB1*04 subtypes were performed using polymerase chain reaction/sequence-specific primers. Association was assessed based on the χ (2) test and odds ratio with 95% confidence interval. For multiple comparisons, p value was corrected (p (c)) with Bonferroni test. Two alleles, HLA-DRB1*04 (p=0.045, p(c)=NS) and HLA-DRB1*10 (p=0.021, p(c)=NS), were found to have increased frequencies in RA patients compared to controls. In contrast HLA-DRB1*08 allele was found to have a decreased frequency in patients compared to controls (p=0.044, p(c)=NS). Molecular subtyping of the most prevalent allele (DRB1*04) revealed increased frequencies of HLA-DRB1*04:05 in patients compared to controls (p=0.013, p(c)=NS) whereas HLA-DRB1*04:02 showed a protective effect (p=0.005, p(c)=0.04). Moreover, stratified analyses indicated statistically significant associations between HLA-DRB1*04 allele and anti-cyclic peptides antibodies positivity (ACPA(+)) and rheumatoid factor positivity (RF(+); p(c)=0.03, for both subgroups), HLA-DRBI*10 and ACPA(+) and the presence of another autoimmune disease (p(c)=0.05 and p(c)=0.007, respectively), and HLA-DRB1*04:05 and RF(+) and erosion (p(c)=0.005 and p(c)=0.049; respectively). A significant decrease in the frequency of the DRB1*04:02 allele was observed in patients with ACPA(+) and RF(+) subgroups (p(c)=0.04 and p(c)=0.02, respectively). Our results showed that there was a trend of positive association of HLA-DRB1*04 and HLA-DRB1*10 with RA as such and significant associations with the disease severity in the south Tunisian population.

Inflammatory bowel disease: susceptibility and disease heterogeneity revealed by human leukocyte antigen genotyping

This study aimed to investigate the association between HLA DR/DQ and inflammatory bowel diseases (IBD) in Tunisian patients and to determine the relationship between HLA DR/DQ alleles with the clinical disease patterns. DNA typing of human leukocyte antigen (HLA) genes was performed in 70 ulcerative colitis (UC) patients, 40 Crohn's disease (CD) patients, and 123 healthy controls (HC) using a polymerase chain reaction sequence specific primer technique. Data were analyzed using Cochran-Mantel-Haenszel test and binary logistic regression. Compared with HC, IBD patients showed an increased frequency of the homozygous DRB1*07 genotype. This positive association was maintained when UC and CD were separately compared to HC. In UC patients, DQB1*03:02 was predictive of colonic extension whereas DRB1*13 and DQB1*03:01 were associated limited disease localization (left-sided colitis and proctitis). The DRB1*15 allele increased in patients with extraintestinal manifestations. In CD, female patients showed an increased frequency of DRB1*13, DRB1*15, and DQB1*06 alleles and DRB1*13-DQB1*06 haplotype, whereas a significant increase of DRB1*07, DQB1*02 alleles, and DRB1*07-DQB1*02 haplotype was noted in male patients. These results show a significant association of the homozygous HLA-DRB1*07 genotype with UC and CD and of several HLA DR/DQ alleles and haplotypes with the clinical phenotypes of these diseases in Tunisian patients. Because of limited statistical power, our study findings are subject to further investigation.

Interleukin-36-receptor antagonist deficiency and generalized pustular psoriasis

BACKGROUND

Generalized pustular psoriasis is a life-threatening disease of unknown cause. It is characterized by sudden, repeated episodes of high-grade fever, generalized rash, and disseminated pustules, with hyperleukocytosis and elevated serum levels of C-reactive protein, which may be associated with plaque-type psoriasis.

METHODS

We performed homozygosity mapping and direct sequencing in nine Tunisian multiplex families with autosomal recessive generalized pustular psoriasis. We assessed the effect of mutations on protein expression and conformation, stability, and function.

RESULTS

We identified significant linkage to an interval of 1.2 megabases on chromosome 2q13-q14.1 and a homozygous missense mutation in IL36RN, encoding an interleukin-36-receptor antagonist (interleukin-36Ra), an antiinflammatory cytokine. This mutation predicts the substitution of a proline residue for leucine at amino acid position 27 (L27P). Homology-based structural modeling of human interleukin-36Ra suggests that the proline at position 27 affects both the stability of interleukin-36Ra and its interaction with its receptor, interleukin-1 receptor-like 2 (interleukin-1 receptor-related protein 2). Biochemical analyses showed that the L27P variant was poorly expressed and less potent than the nonvariant interleukin-36Ra in inhibiting a cytokine-induced response in an interleukin-8 reporter assay, leading to enhanced production of inflammatory cytokines (interleukin-8 in particular) by keratinocytes from the patients.

CONCLUSIONS

Aberrant interleukin-36Ra structure and function lead to unregulated secretion of inflammatory cytokines and generalized pustular psoriasis. (Funded by Agence Nationale de la Recherche and Société Française de Dermatologie.).

Candida glabrata strain relatedness by new microsatellite markers

We investigated six microsatellite markers to type 85 unrelated and 118 related isolates of Candida glabrata from 36 patients. Three new markers were selected from the complete sequence of CBS138 and three previously described markers, RPM2, MTI and ERG3 were used. We found a genetic diversity of 0.949 by combining four of them. By applying the new microsatellite markers GLM4, GLM5 and GLM6 we were able to discriminate 29 isolates, originally identified by the more established markers, RPM2, MTI and ERG3. When epidemiologically closely related isolates from 36 patients were typed, 25 patients (72%) exhibited identical or highly related multilocus genotypes. We noted a microvariation in 4 of the patients. This minor change of one locus could be explained by a single step mutation. Since one of these patients had not received antifungal treatment; thus, the relationship between genome variation and antifungal therapy remains controversial. We can conclude from our analysis of these new microsatellite markers that they are highly selective and therefore should be considered as a useful typing system for differentiating related and unrelated isolates of C. glabrata, as well as being able to detect microvariation.

Microsatellite analysis and susceptibility to FCZ of Candida glabrata invasive isolates in Sfax Hospital, Tunisia

We have noted that, during the last few years, there has been a redistribution of the most common Candida species with an increase in non-C. albicans Candida species, particularly Candida glabrata. In many countries, the high frequency of Candida glabrata shows the highest resistance rates. The main objective of this investigation was to analyze the genotypic variability of invasive C. glabrata isolates recovered over a period of six years and assess their in vitro susceptibility to fluconazole to determine the possible existence of relationships between genotype and susceptibility. We collected 50 invasive C. glabrata isolates (21.4%) from January 2001 to December 2007. The in vitro susceptibility profiles as determined by the E-test method showed that 8.3% of the isolates were resistant to fluconazole. The typing with three microsatellite markers RPM2, MTI and ERG3 demonstrated 12 multilocus genotypes distributed irregularly with a predominance of G1 (38%). A cluster (G9) was found among isolates collected in the same ward, at the same time period, suggesting cross transmission. Eleven of 13 patients who had previously been colonized by C. glabrata, were infected by their colonizing strains. However, we noted after prolonged treatment with fluconazole that there was an increase of the MIC for an isolate from one patient and in another patient, the selection of a more resistant variant. In our study, we didn't find an association between genotype and susceptibility to fluconazole. In conclusion, the predominance of some genotypes could be explained by nosocomial transmission or a selective ecological advantage rather than an emergence of a resistant isolate.

MHC class I and class II genes in Tunisian patients with reactive and undifferentiated arthritis

OBJECTIVE

To study HLA class I and class II association in Tunisian patients with reactive (ReA) and undifferentiated arthritis (UA).

METHODS

The study included 17 patients with ReA defined according to the European Spondylarthropathy Study Group criteria for spondylarthropathy (SpA), 11 patients classified as having undifferentiated arthritis and 100 unrelated healthy controls. HLA class I antigens were typed serologically and HLA class II alleles were genotyped molecularly by the polymerase chain reaction with sequence-specific primers technique.

RESULTS

There was a major difference between HLA alleles in ReA and UA patients when compared separately with controls. Increased frequencies of HLA-B27 (p=7.76 10-12, OR=59.30), HLA-B51 (p=0.015, OR=4.91) and HLA-DRB1*04 (p=0.033, OR=2.90) alleles were found in patients with ReA but not in patients with UA. HLA-B27 was not expressed totally in our cohort of UA patients. A significant increase of HLA-B15 (p=0.002, OR=18.40) and a moderate increase of HLA-B7 (p=0.043, OR=5.15) was found in patients with UA, but not in patients with ReA. In the B27 negative patients, HLA-DRB1*04 association with ReA was found independently of B27.

CONCLUSION

Our data confirmed a significant association of HLA-B27 with ReA in the Tunisian population. Our results also suggested that some of the additional HLA antigens were associated with ReA including HLA-B51 and HLA-DRB1*04 alleles. UA seemed to have a genetic background different from ReA in Tunisian patients.

[Susceptibility markers in Tunisian first-degree relatives of patients with type 1 diabetes]

To identify the profile of anti-pancreas autoantibodies and elucidate the HLA DRB1, DQB1 polymorphism in Tunisian first-degree relatives of patients with type 1 diabetes, we recruited 96 relatives from 21 families with at least one diabetic child. Islet cell antibodies (ICA) were detected by immunofluorescence on monkey pancreas; glutamate decarboxylase (GADA), IA2 (IA2-A) and insulin (IAA) antibodies were measured by RIA. HLA class II DRB1 and DQB1 alleles were typed by PCR-SSP. ICA, GADA, IA2-A and IAA were found in respectively 11.5, 4.2, 5.2 and 8.3% of relatives. Twenty-two out of 96 had at least one antibody and 20 out of these 22 had a susceptibility allele (DRB1*03, DRB1*04, DQB1*02 or DQB1*0302) with or without protective allele (DRB1*11, DRB1*13, DRB1*15 or DQB1*06). All of the 5 relatives having 2 autoantibodies or more carried the DRB1*04-DQB1*0302 susceptible haplotype. In conclusion, this observational study confirms in a Tunisian population known epidemiological data and demonstrates the usefulness of follow-up to determine the predictive value of studied markers.

[Nonresponse to hepatits B vaccine in health care workers]

The authors report the results of an investigation of witness cases realised in collaboration between Occupational Medecine Service and Immunology Laboratory of Hedi CHAKER University Hospital SFAX during the year 2000. The purpose was to search the genetic control of the HLA class I system for the non-response to hepatitis B vaccine and to evaluate the contribution of other favorite factors as tabac, sex, age. Thus, in a population of 32 healthy agents found nonresponders to hepatitis B vaccine by the titers of anti HBs antibody, we have performed the HLA-A, -B phenotypes by the technique of complement dependent microcytotoxicity. The frequency of studied HLA class I antigens, was compared for the non-responders group, to the frequency observed in witnesses group, done with 52 responders healthy agents. The rate of nonresponsiveness hepatitis B vaccine was evaluated up to 5 %. Statistically significant difference was observed for HLA A1 and-B44 markers showing fraquencies which were considerably higher in the non-responders than in witnesses.