Wajih Kaabachi

Association between vitamin D receptor polymorphisms and multiple sclerosis: systematic review and meta-analysis of case–control studies

Vitamin D receptor (VDR) polymorphisms have been studied as potential contributors to multiple sclerosis (MS). However, published studies differ with respect to study design and the significance of the effects detected. The aim of this study was to quantify the magnitude of the risk associated with the TaqI, BsmI, ApaI and FokI VDR polymorphisms in MS using a meta-analysis approach. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we conducted a systematic search and meta-analysis of the literature. Subgroup analyses were performed to detect potential sources of heterogeneity from the selected study characteristics. The stability of the summary risk was evaluated using sensitivity analyses. The meta-analysis included a total of 3300 cases and 3194 controls from 13 case–control studies. There were no significant associations found between TaqI and BsmI polymorphisms and MS risk. The association between the ApaI polymorphism and MS risk was significant in the homozygous and codominant models (P=0.013 and P=0.031, respectively), suggesting that the AA ApaI genotype might be a significant MS risk factor. Publication year and age significantly affected the association between TaqI polymorphisms and MS (P=0.014 and P=0.010, respectively), which indicates a protective effect of the major T allele. The AA ApaI and FF FokI genotypes are significant risk factors for MS. The association between the TaqI polymorphism and MS risk is significantly affected by study characteristics.

Induced sputum levels of IL-33 and soluble ST2 in young asthmatic children

Abstract Objective: Interleukin-33 is an IL-1 family cytokine which signals via its T1/ST2 receptor, and acts as a key regulator of inflammation, notably the type-2 response implicated in asthma. This study aims to measure the expression of soluble ST2 (sST2) and IL-33 in asthmatic children, depending on disease activity. Methods: Thirty-seven children with well-defined asthma (20 moderate and 17 mild asthmatics) were studied. IL-33 and sST2 were measured by ELISA in serum and induced sputum (IS) samples, and compared with 22 age- and sex-matched healthy controls. Real-time quantitative PCR was used to determine IL-33 and TNF-α mRNA expression in IS. Results: sST2 and IL-33 levels in IS and serum were significantly higher in patients compared with healthy controls (p = 0.0001). The increase in sST2 and IL33 was significantly more important in moderate cases than in mild asthma. A significant correlation was observed between serum and IS IL-33 levels (r = 0.497; p = 0.0018). Higher levels of IL-33 mRNA were detected in IS from asthmatics than those observed in controls. A significant correlation was found between TNF-α and IL-33 mRNA expression in the asthmatic subjects (r = 0.772, p = 0.0001). Conclusions: Values of sST2 and IL-33 observed in IS were found to correlate with disease activity. Elevated IL-33 mRNA expression in IS and its correlation with TNF-α reflected the inflammatory process observed in the lung of young asthmatics.

Contribution of VDR polymorphisms to type 1 diabetes susceptibility: Systematic review of case–control studies and meta-analysis

Vitamin D receptor (VDR) polymorphisms have been inconsistently investigated in type 1 diabetes (T1D). However, the results are inconsistent and inconclusive. The current study aimed to investigate the role of TaqI, BsmI, ApaI and FokI VDR polymorphisms in T1D disease. Following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines, a systematic search and meta-analysis of the literature, since 1998 until december 2013, was conducted. Subgroup analyses were performed to detect potential sources of heterogeneity from selected study characteristics. Meta-analyses yielded a non-significant association of TaqI polymorphism with T1D [OR=1.014 (0.783-1.312); P=0.918] in the recessive model. The BsmI polymorphism was not associated with T1D [OR=1.44 (0.944-1.386); P=0.171] in the dominant model. Also, ApaI polymorphism was not associated with T1D risk [OR=0.996 (0.859-1.155); P=0.960] in the homozygous model. The FokI polymorphism was not associated with T1D risk [OR=0.968 (0.743-1.263); P=0.813] in dominant model. Stratification according to study characteristics showed that publication year, age, gender, estimated vitamin D levels and latitude moderated significantly association between VDR polymorphisms and T1D disease. Meta-analysis on haplotypes revealed that BAT might be a significant risk factor for T1D [OR=1.331 (0.957-1.850; P=0.089]. However, the bAT was found to be a significant protective factor [OR=0.639 (0.460-0.887); P=0.007]. As conclusion, individual VDR polymorphisms seemed not to be associated with T1D risk. However, haplotypes contributed significantly to disease susceptibility. Study characteristics moderated the association between VDR polymorphisms and T1D. These results suggested that, in T1D pathogenesis, VDR polymorphisms interact with each other and with environmental factors.

Vitamin D reduces the differentiation and expansion of Th17 cells in young asthmatic children.

Vitamin D [25(OH)D3] deficiency has been associated with asthma as in many inflammatory and autoimmune pathologies; however, there is still a lack of data about the effects of administration of vitamin D in immune regulation in young asthmatic patients. In this study, we investigated its inhibitory effect on the immune response in young asthmatic patients and the possible mechanisms involved. Peripheral blood CD4(+) T cells from 10 asthmatic patients and 10 healthy controls were cultured under Th17 polarizing conditions in the presence or absence of [25(OH)D3], IL-17 cytokine production was determined by ELISA and flow cytometry. Messenger RNA (mRNA) expression of several factors related to Th17 cell function was determined by real-time PCR. The effect of [25(OH)D3]-treated dendritic cells (DCs) on CD4(+) T cell response was determined by ELISA and flow cytometry. Stimulation of naive CD4(+) T cells under Th17 polarizing conditions showed a higher Th17 cell differentiation in asthmatic patients than healthy controls. The addition of [25(OH)D3] significantly inhibited Th17 cell differentiation both in patients [P<0.001] and in normal controls [P=0.001] in a dose-dependent way. [25(OH)D3] was able to inhibit the gene expression of RORC, IL-17, IL-23R, and CCR6. [25(OH)D3]-treated DCs significantly inhibited IL-17 production [P=0.002] and decreased the percentage of CD4(+)IL-17(+) [P=0.007] in young asthmatics. The findings suggest that the inhibitory effect of [25(OH)D3] on the Th17 response was mediated via both T cells and DCs. DCs pathway is involved in the direct inhibition of 25(OH)D3 on Th17 cell differentiation in young asthmatics.

Interleukin-17A and -17F genes polymorphisms in lung cancer

Interleukin-17 (IL-17) is a proinflammatory cytokines produced by T helper 17 (Th17) cells, which plays an important role in both innate and adaptive immune systems. Genetic variants in the IL-17 genes may influence the immunopathogenesis of many cancers. In our study, we investigated the association of three single-nucleotide polymorphisms (SNPs: -152 G/A, 7488 A/G and 7383 A/G) in the IL-17A and IL-17F genes with lung cancer risk, in the Tunisian population. The genotypic and allelic distributions of IL-17A and IL-17F genes polymorphisms were analyzed by Polymerase Chain-Reaction (PCR) and Restriction Fragment Length Polymorphism (RFLP) for 239 patients and 258 healthy controls. Our results revealed a statistically significant association between IL-17F 7488G allele and increased lung cancer risk (P=0.028). Stratification analysis indicated that IL-17F 7488G allele enhances the risk of lung cancer development among men and oldest age subject groups (P<0.05). Patients with IL-17F 7488G allele were also more likely to be diagnosed at advanced stage (P=0.04), or with metastatic lung cancer (P=0.035). Furthermore, no significant association between IL-17F 7383 A/G, IL-17 -152G/A polymorphisms and lung cancer risk was observed (P>0.05). However, we reported contradictory findings on the association of IL-17 -152 G/A polymorphisms with lung cancer risk. In addition, we suggested the existence of a biological interaction between IL-17A, but not IL-17F polymorphisms and smoking. Our findings suggest that IL-17F 7488G allele is associated with increased lung cancer risk in the Tunisian population.

Interleukin-37 expression is decreased in Behcet's disease and is associated with inflammation.

Interleukin-37 (IL-37) exerts broad inhibitory properties on the innate inflammatory and acquired immune responses. This study was set up to investigate the expression of IL-37 in Behçet disease (BD) and to explore its possible regulatory role during inflammation. IL-37 protein levels and mRNA expression in lipopolysaccharides (LPS)-stimulated peripheral blood mononuclear cells (PBMCs) from 50 BD (30 patients in active stage) patients and 20 healthy controls were assayed by real-time polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). Cytokines in the serum and the supernatants of stimulated PBMCs and CD4(+) T cells were assayed by ELISA. Active BD patients showed a decreased IL-37 expression and increased IL-1β, IL-6, and tumor necrosis factor-alpha (TNF-α) levels in serum and in PBMC culture supernatants. Active BD patients treated with corticosteroids showed an enhanced IL-37 production. Recombinant IL-37 (rIL-37) induced a significant decrease of inflammatory cytokines (IL-1β, IL-6, and TNF-α). It also markedly decreased IL-17 expression in PBMCs and CD4(+) T cells from active BD patients. The present study suggests that a decreased IL-37 expression in BD patients is associated with an increased inflammatory response. Corticosteroid treatment of active BD patients is associated with an increased expression of IL-37 mRNA, which suggests that treatment may partly exert its immunosuppressive effect by regulating IL-37 production and reducing inflammatory cytokines.

Vitamin D receptor TaqI and ApaI polymorphisms: A comparative study in patients with Behçet’s disease and Rheumatoid arthritis in Tunisian population

Recent genetic surveys have identified vitamin D receptor (VDR) as a susceptibility gene for several autoimmune diseases. This study was designed to investigate the association of VDR gene polymorphisms with Behçets disease (BD) and Rheumatoid arthritis (RA). A case-control study including 151 BD, 106 RA patients and an appropriate number of healthy control subjects were performed using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) techniques. Association between TaqI polymorphism and BD was marginal under codominant and recessive models (P=0.078 and P=0.058, respectively). After stratification, we found evidence for a significant association between TaqI polymorphism and BD in the elderly subjects (P=0.037). The minor ApaI a allele tended to confer an increased risk for BD susceptibility (P=0.087). BD patients with VDR homozygous AA or aa genotypes were at increased risk for development of erythema nodosum (EN) skin manifestation (P=0.038). No significant association was observed for VDR ApaI and TaqI polymorphisms with RA risk (P>0.05). TaqI and ApaI polymorphisms might be modestly implicated in BD pathogenesis. They could be considered as potential biomarkers in BD rather than susceptibility genes. However, TaqI and ApaI seemed not to be implicated in RA pathogenesis.

Pulmonary manifestations in Behçet disease: impaired natural killer cells activity

BackgroundBehçet’s disease (BD) is a systemic vasculitis with unknown aetiology, where, besides genetic predisposition, an immune dysregulation involving T and B lymphocytes and hyperactive neutrophils contribute to disease pathogenesis. The aim of this study was to determine the cytotoxicity of natural killer (NK) cells in bronchoalveolar lavage (BAL) from BD patients with pulmonary manifestations.MethodsBAL was performed in 27 patients with BD and pulmonary manifestations, 14 patients with Rheumatoid Arthritis (RA) and 23 healthy controls (HC). Related orphan receptor C (RORC) and forkheadbox P3 (FOXP3) mRNA transcript were determined in BAL by reverse transcription–polymerase chain reaction (RT-PCR). NK cells, NK cell cytotoxicity, and lymphokine-activated killer (LAK) activity against K562 cells were measured by flow cytometry. Proportions of NK precursors and expression of genes for IL-2 receptor β (IL-2Rβ; CD122), perforin, and granzyme in NK cells were measured by flow cytometry or RT-PCR.ResultsThe analysis of transcription factors revealed an increase in the RORC/FOXP3 ratio (Th17/Treg cells) in BAL from BD patients. Percentages of NK were significantly lower in BD than in RA patients and healthy controls. Purified NK cells derived from BD patients were found to have lower cytotoxicity and LAK activity than those from controls. This defect of NK cells in BD patients was related to down-regulation of perforin and granzyme expression in NK cells.ConclusionIn BD patients, the increased RORC/FOXP3 ratio indicated an inflammatory state of the lung. NK cells were decreased together with an impairment of their activity due to a defective expression of granzyme and perforin. These abnormalities possibly contribute to immune system dysregulation found in BAL of BD patients with pulmonary manifestations.

Increased interleukin 33 in patients with neuro-Behcet's disease: correlation with MCP-1 and IP-10 chemokines

Increased interleukin 33 in patients with neuro-Behcets disease: correlation with MCP-1 and IP-10 chemokines

Soluble ST2 and IL-33: Potential markers of endometriosis in the Tunisian population.

Interleukin-33 is an IL-1 family cytokine which signals via its T1/ST2 receptor, and acts as a key regulator of inflammation. This study aims to measure the expression of soluble ST2 (sST2) and IL-33 in endometriosis. We investigated thirty women with laparoscopic and histopathological confirmed endometriosis and 20 control women without pelvic pathology. Peripheral blood mononuclear cells and peritoneal fluid (PF) were assessed for sST2 and IL-33 levels that are measured by sandwich enzyme-linked immunosorbent assay. Peritoneal fluid IL-33 mRNA expression was quantified by real-time reverse transcription polymerase chain reaction assays. We found that IL-33 levels in PF and in serum were significantly higher in patients with endometriosis compared to women without endometriosis (P < 0.05). IL-33 increased levels were significantly more important in PF [10.45 ± 14.33 ng/mL] than in serum [2.68 ± 1.54 ng/mL] from endometriosis patients. Higher levels of IL-33 mRNA expression were detected in PF from patients with endometriosis. Soluble ST2 levels in PF were significantly different between patients [2.96 ± 0.98 ng/mL; P < 0.0001] and controls [0.88 ± 0.076 ng/mL]. Serum sST2 levels were similarly expressed in endometriosis patients and in controls (P > 0.05). Significant correlation was observed between IL-33 and sST2 levels in PF. In conclusion, IL-33 and sST2 values observed in PF were found to correlate with endometriosis severity. Elevated and correlated PF IL-33 and sST2 levels from patients with endometriosis suggested a potential role as surrogate markers of disease activity.