Toll-like receptor 4 Asp299Gly and Thr399Ile polymorphisms: New data and a meta-analysis

MicroRNA-218-5p regulates inflammation response via targeting TLR4 in atherosclerosis

BACKGROUND

To investigate the expression of miR-218-5p in atherosclerosis patients and its effect on ox-LDL induced THP-1-derived macrophage inflammatory response.

METHODS

RT-qPCR detected the expression of serum miR-218-5p, and the diagnostic value of miR-218-5p was analyzed by ROC curve. Pearson correlation coefficient was used to evaluate the correlation between miR-218-5p and CIMT and CRP. THP-1 cells were treated with ox-LDL to construct foam cell model. The expression of miR-218-5p was regulated by in vitro transfection technique, and the effects of miR-218-5p on cell viability, apoptosis and inflammation were investigated. Luciferase reporter genes were used to analyze target genes of miR-218-5p in cell models.

RESULTS

The expression of miR-218-5p in the atherosclerosis cohort was significantly reduced, and miR-218-5p showed a good ability to distinguish patients from healthy people. Correlation analysis showed that the level of miR-218-5p was negatively correlated with the levels of CIMT and CRP. Cytological studies showed that the expression of miR-218-5p in macrophages decreased after ox-LDL induction. ox-LDL treatment on macrophages resulted in decreased cell viability, increased cell apoptosis and production of inflammatory cytokines, which contributed to the exacerbation of plaque formation. However, the above situation was reversed after upregulation of miR-218-5p. Bioinformatics analysis showed that TLR4 may be the target gene of miR-218-5p, and this hypothesis was proved by luciferase reporter gene assay.

CONCLUSIONS

The expression of miR-218-5p is reduced in atherosclerosis, and it may regulate the inflammatory response of atherosclerotic foam cells by targeting TLR4, suggesting that miR-218-5p may be a promising target for clinical atherosclerosis therapy.

Biallelic TLR4 deficiency in humans

BACKGROUND

Toll-like receptors (TLRs) mediate functions for host defense and inflammatory responses. TLR4 recognizes LPS, a component of gram-negative bacteria as well as host-derived endogenous ligands such as S100A8 and S100A9 proteins.

OBJECTIVE

We sought to report phenotype and cellular function of individuals with complete TLR4 deficiency.

METHODS

We performed genome sequencing and investigated exome and genome sequencing databases. Cellular responses were studied on primary monocytes, macrophages, and neutrophils, as well as cell lines using flow cytometry, reporter, and cytokine assays.

RESULTS

We identified 2 individuals in a family of Qatari origin carrying a homozygous stop codon variant p.Q188X in TLR4 presenting with a variable phenotype (asymptomatic and inflammatory bowel disease consistent with severe perianal Crohn disease). A third individual with homozygous p.Y794X was identified in a population database. In contrast to hypomorphic polymorphisms p.D299G and p.T399I, the variants p.Q188X and p.Y794X completely abrogated LPS-induced cytokine responses whereas TLR2 response was normal. TLR4 deficiency causes a neutrophil CD62L shedding defect, whereas antimicrobial activity toward intracellular Salmonella was intact.

CONCLUSIONS

Biallelic TLR4 deficiency in humans causes an inborn error of immunity in responding to LPS. This complements the spectrum of known primary immunodeficiencies, in particular myeloid differentiation primary response 88 (MYD88) or the IL-1 receptor-associated kinase 4 (IRAK4) deficiency that are downstream of TLR4 and TLR2 signaling.

TLR4 polymorphisms as potential predictors of atopic dermatitis in Chinese Han children

Background

Toll‐like receptor 4 (TLR4) is considered to be involved in the pathogenesis and progression of atopic dermatitis (AD). In the present study, we evaluated the relationship between TLR4 gene polymorphisms and the susceptibility or severity of AD among Chinese Han children.

Methods

A total of 132 AD patients and 100 healthy controls were enrolled in this study. Four single‐nucleotide polymorphisms (rs19277914, rs11536891, rs7869402, and rs11536889) of the TLR4 gene were genotyped by multiplex PCR combined with next‐generation sequencing.

Results

Our results showed that a significantly reduced risk for AD was associated with C allele [p = 0.008; odds ratio (OR) = 0.41, C vs. T], TC genotype (p = 0.022; OR = 0.41, TC vs. TT), and TC + CC genotype (p = 0.010; OR = 0.39, TC + CC vs. TT) of TLR4 rs11536891. The frequency of the haplotype GCCG (rs1927914–rs11536891–rs7869402–rs11536889) in AD patients was lower than that in the controls (p = 0.010; OR = 0.38). Moreover, the results indicated that a higher risk of severe AD was related to the T allele (p = 0.019; OR = 2.97, T vs. C) and the TC genotype (p = 0.021; OR = 3.34, TC vs. CC) of TLR4 rs7869402. A risk haplotype of TLR4 (GTTG) was found in severe AD patients (p = 0.010; OR = 5.26).

Conclusions

Our data suggested that TLR4 rs11536891 polymorphism was associated with the susceptibility to AD in Chinese Han children. And TLR4 rs7869402 might confer the severity of pediatric AD patients.

Neuroinflammation Upregulated Neuronal Toll-Like Receptors 2 and 4 to Drive Synucleinopathy in Neurodegeneration

Background: Parkinson’s disease (PD) is characterized by intraneuronal α-synuclein aggregation called Lewy bodies and progressive dopaminergic neurodegeneration. Toll-like receptor (TLR) signaling is a major pathway mediating inflammation. The molecular link on how neuroinflammation upregulates neuronal TLRs and induces accumulation of α-synuclein aggregates to drive synucleinopathy remains to be determined.

Objective: Despite conditioned medium from microglia and TLR agonists were utilized to study their effects on neuronal cells, a Transwell coculture system, comprising lipopolysaccharide-activated microglia on top and retinoic acid-differentiated SH-SY5Y cells at the bottom more mimicking in vivo neuroinflammation, was employed to elucidate the mechanism of activated microglia on neuronal cells.

Methods: Genetic variants of TLRs in PD patients were genotyped and the multiplex cytokines, sRAGE, and HMGB1were assessed. A coculture system was employed to measure α-synuclein aggregates and neurite shortening by confocal microscope. The expression of TLR2/4 and autophagy flux was detected by western blot and immunofluorescence.

Results: PD patients showed higher plasma levels of proinflammatory cytokines and genetic TLR4 variant, c.896 A > G (p. D299G). Elevated proinflammatory cytokines in coculture medium was also seen. Phosphorylation and aggregation of α-synuclein, shortening of neurite, upregulation of TLR2/4 expression, activation of downstream p38 and JNK, and dampening of autophagic flux were seen in SH-SY5Y cells cocultured with activated microglia. Those were prevented by inhibiting TLR2/4 and p38/JNK signaling.

Conclusion: Activated microglia-derived neuroinflammation induced neuronal TLR2/4-p38/JNK activation to perturb autophagy, causing accumulation of α-synuclein aggregates and neurite shortening. Targeting neuronal TLR2/4 pathway might be a mechanistic-based therapy for neurodegenerative disease, such as PD.

Toll-Like Receptor 4 Polymorphisms (896A/G and 1196C/T) as an Indicator of COVID-19 Severity in a Convenience Sample of Egyptian Patients

Background

The clinical spectrum of COVID-19 is extremely variable. Thus, it is likely that the heterogeneity in the genetic make-up of the host may contribute to disease severity. Toll‐like receptor (TLR)-4 plays a vital role in the innate immune response to SARS-CoV-2 infection. The susceptibility of humans to severe COVID-19 concerning TLR-4 single nucleotide polymorphisms (SNPs) has not been well examined.

Objective

The goal of this research was to investigate the association between TLR-4 (Asp299Gly and Thr399Ile) SNPs and COVID-19 severity and progression as well as the cytokine storm in Egyptian patients.

Methods

We genotyped 300 adult COVID-19 Egyptian patients for TLR-4 (Asp299Gly and Thr399Ile) SNPs using PCR-restriction fragment length polymorphism (PCR-RFLP). We also measured interleukin (IL)-6 levels by enzyme-linked immunosorbent assay (ELISA) as an indicator of the cytokine storm.

Results

The minor 299Gly (G) and 399Ile (T) alleles were associated with a significant (P < 0.001) positive risk of severe COVID-19 (OR = 3.14; 95% CI = 2.02–4.88 and OR = 2.75; 95% CI = 1.66–4.57), their frequency in the severe group were 71.8% (84/150) and 70.7% (58/150), respectively. We detected significant differences between TLR-4 (Asp299Gly, Thr399Ile) genotypes with regard to serum levels of IL-6. Levels of IL-6 increased significantly with the presence of the mutant 299Gly (G) and 399Ile (T) alleles to reach the highest levels in the Gly299Gly (GG) and the Ile399Ile (TT) genotypes (170 pg/mL (145–208.25) and 112 pg/mL (24–284.75), respectively).

Conclusion

The TLR-4 (Asp299Gly and Thr399Ile) minor alleles 299Gly (G) and 399Ile (T) are associated with COVID-19 severity, mortality, and the cytokine storm.

Anti-inflammatory/anti-apoptotic impact of betulin attenuates experimentally induced ulcerative colitis: An insight into TLR4/NF-kB/caspase signalling modulation

Ulcerative colitis (UC) is an inflammatory bowel disease with limited therapeutic management approaches. The present study evaluated the potential therapeutic impact of betulin on acetic acid (AA)-induced UC in rats. UC was induced by intracolonic instillation of AA (3% v/v). Rats were treated with betulin (8 mg/kg, I.P., once daily) four days post AA instillation and for 14 consecutive days. Betulin attenuated AA-induced UC as evidenced by retracted macroscopic scores, serum CRP titre and LDH activity, attenuated histopathological hallmarks of UC including mucosal necrosis, haemorrhage, congestion and inflammatory cells infiltration. Moreover, betulin dampened UC-associated colonic inflammatory load with modulation of TLR4/NF-kB axis and reduction in colonic inflammatory cytokines; TNF-α, IL1β and IL-6. Nevertheless, betulin suppressed colonic apoptosis with reduced colonic caspase-3 and caspase-8 expression. The current findings confirm a beneficial therapeutic impact of betulin against UC. The prospective underlying mechanisms include down-regulation of TLR4/NF-κB and the subsequent downstream signalling pathways.

Molecular Basis of Artemisinin Derivatives Inhibition of Myeloid Differentiation Protein 2 by Combined in Silico and Experimental Study

Artemisinin (also known as Qinghaosu), an active component of the Qinghao extract, is widely used as antimalarial drug. Previous studies reveal that artemisinin and its derivatives also have effective anti-inflammatory and immunomodulatory properties, but the direct molecular target remains unknown. Recently, several reports mentioned that myeloid differentiation factor 2 (MD-2, also known as lymphocyte antigen 96) may be the endogenous target of artemisinin in the inhibition of lipopolysaccharide signaling. However, the exact interaction between artemisinin and MD-2 is still not fully understood. Here, experimental and computational methods were employed to elucidate the relationship between the artemisinin and its inhibition mechanism. Experimental results showed that artemether exhibit higher anti-inflammatory activity performance than artemisinin and artesunate. Molecular docking results showed that artemisinin, artesunate, and artemether had similar binding poses, and all complexes remained stable throughout the whole molecular dynamics simulations, whereas the binding of artemisinin and its derivatives to MD-2 decreased the TLR4(Toll-Like Receptor 4)/MD-2 stability. Moreover, artemether exhibited lower binding energy as compared to artemisinin and artesunate, which is in good agreement with the experimental results. Leu61, Leu78, and Ile117 are indeed key residues that contribute to the binding free energy. Binding free energy analysis further confirmed that hydrophobic interactions were critical to maintain the binding mode of artemisinin and its derivatives with MD-2.

Anti-TNF-α Therapy Suppresses Proinflammatory Activities of Mucosal Neutrophils in Inflammatory Bowel Disease

Neutrophils have been found to play an important role in the pathogenesis of inflammatory bowel disease (IBD), and anti-TNF-α mAb (i.e., infliximab) therapy is demonstrated to be effective in the induction of clinical remission and mucosal healing in these patients. However, how anti-TNF-α mAb regulates the functions of neutrophils is still unknown. Herein, we found that anti-TNF-α therapy significantly downregulated infiltration of neutrophils in inflamed mucosa of IBD patients. Importantly, anti-TNF-α mAb could inhibit neutrophils to produce proinflammatory mediators, such as ROS, calprotectin, IL-8, IL-6, and TNF-α. These data indicate that TNF-α plays a critical role in the induction of mucosal inflammatory response, and that blockade of TNF-α modulates intestinal homeostasis through balancing immune responses of neutrophils.

Association between Toll-Like Receptor 4 T399I Gene Polymorphism and the Susceptibility to Crohn's Disease: A Meta-Analysis of Case-Control Studies

BACKGROUND/AIMS

This article was undertaken to investigate the association of toll-like receptor 4 (TLR4) polymorphism (Thr399Ile) and risk of Crohn's disease (CD) by performing a meta-analysis.

METHODS

Articles were chosen based on PubMed, Embase, China National Knowledge Internet, and Chinese Wanfang databases (up to 12th October 2016). Specific inclusion criteria were used to evaluate articles. Meta-analysis was performed by using a random or fixed effect model. Fifteen eligible case-control studies were finally included into this meta-analysis. We estimated the summary OR with its corresponding 95% CI to assess the association.

RESULTS

Summary results of this meta-analysis showed a moderate association between the TLR4 T399I polymorphism and the risk of CD (allele model: OR 1.26, 95% CI 1.06-1.50, p = 0.009; heterozygote model: OR 1.36, 95% CI 1.11-1.66, p = 0.003; dominant model: OR 1.35, 95% CI 1.10-1.64, p = 0.004; homozygote model: OR 1.08, 95% CI 0.44-2.64, p = 0.866; recessive model: OR 0.97, 95% CI 0.40-2.35, p = 0.946). Stratified analysis on geographical area, ethnicity, and genotypic methods suggested that the polymorphism was associated with increased risk of CD in Asia and Asians, and "T" allele only moderately increased CD risk within polymerase chain reaction-restricted fragment length polymorphism.

CONCLUSIONS

Our meta-analysis suggests that TLR4 T399I polymorphism is moderately associated with susceptibility to CD, and more studies are needed to confirm our conclusion.

Functional variants in intercellular adhesion molecule-1 and toll-like receptor-4 genes are more frequent in children with febrile urinary tract infection with renal parenchymal involvement

AIM

We studied the functional polymorphisms of intercellular adhesion molecule-1 (ICAM-1) and toll-like receptor-4 (TLR-4) genes and risk of acute pyelonephritis (APN) in children attending Assiut University Children's Hospitals, Egypt, from 2011 to 2015.

METHODS

Urinary tract infections (UTIs) were diagnosed in 380 children: 98 had APN and 282 had lower UTIs. Four single-nucleotide polymorphisms in ICAM-1 and TLR-4 genes were genotyped in all subjects: ICAM-1 rs1799969 Gly241Arg, ICAM-1 rs5498 Glu469Lys, TLR-4 rs4896791 Thr399Ile and TLR-4 rs4896790 Asp299Gly.

RESULTS

Patients with APN were significantly more likely to have AA genotype of the ICAM-1 rs5498 (1462 A/G) polymorphism (p = 0.04) than children with lower UTIs and the TLR-4 Asp299Gly GG genotype (p = 0.002) and G allele (p = 0.006) than healthy controls. The association with the ICAM-1 Glu469Lys (1462A/G) was less evident. The GG genotype was associated with a modest relative risk of 1.4 (p = 0.1) of developing APN, but was not an independent odds ratio, at 1.2 (p = 0.48).

CONCLUSION

Functional variants in ICAM-1 and TLR-4 genes were increasingly common in children with febrile UTIs with renal parenchymal involvement, but the ICAM-1 Glu469Lys (1462A/G) association was less evident. TLR4 Asp299Gly might independently increase renal parenchymal infection rather than renal scarring.

Polymorphisms in oxidative pathway related genes and susceptibility to inflammatory bowel disease

AIM

To investigate whether common variants in the oxidative pathway genes influence inflammatory bowel disease (IBD) risk among Moroccan patients.

METHODS

The distribution of (TAAA)n_rs12720460 and (CCTTT)n _rs3833912 NOS2A microsatellite repeats, HIF-1A_rs11549467 and NFKB1-94ins/delATTG_rs28362491 was analyzed in 507 subjects grouped in 199 IBD and 308 healthy controls. Genotyping was performed with polymerase chain reaction-fluorescent method and the TaqMan^® allelic discrimination technology.

RESULTS

The allele and genotype frequencies of HIF1A_ rs11549467, NFKB1_rs28362491 and NOS2A_ (TAAA)n did not differ significantly between patients and controls. Analysis of NOS2A_ (CCTTT)n markers evidenced differences between patients and healthy controls. A preferential presence of the (CCTTT)8 (P = 0.02; OR = 1.71, 95%CI: 1.07-2.74), (CCTTT)14 (P = 0.02; OR = 1.71, 95%CI: 1.06-2.76) alleles in IBD, (CCTTT)8 (P = 0.008; OR = 1.95, 95%CI: 1.17-3.23) in CD and (CCTTT)7 (P = 0.009; OR = 7.61, 95%CI: 1.25-46.08), (CCTTT)11 (P = 0.05; OR = 0.51, 95%CI: 0.25-1.01), (CCTTT)14 (P = 0.02; OR = 2.05, 95%CI: 1.07-3.94), (CCTTT)15 (P = 0.01; OR = 2.25, 95%CI: 1.16-4.35) repeats in UC patients indicated its possible association with higher disease risk which need to be confirmed in a larger sample size.

CONCLUSION

Our results suggest that the NOS2A_ (CCTTT)n gene variations may influence IBD susceptibility in the Moroccan population.

Genetic association and phenotypic correlation of TLR4 but not NOD2 variants with Tunisian inflammatory bowel disease

OBJECTIVE

The common association between NOD2/CARD15 and TLR4 gene variants with inflammatory bowel disease (IBD) has not been replicated in all studies. We studied the polymorphism of these two genes in Tunisian patients with IBD.

METHODS

Polymorphisms of NOD2 (R702W, G908R and L1007fs) and TLR4 (Asp299Gly and Thr399Ile) genes were analyzed in 106 patients with IBD (68 with ulcerative colitis [UC], 38 with Crohn's disease [CD]) and 160 healthy controls using polymerase chain reaction-restriction fragment length polymorphism. Genotypes and phenotypes were correlated.

RESULTS

The mutated allele of TLR4-Thr399Ile was strongly associated with IBD (9.4% in IBD, 7.4% in UC and 13.2% in CD vs 2.5% in controls; P = 0.0004, 0.014 and 0.00006, respectively). Heterozygous genotypes were significantly more frequent in patients with IBD (17.0%), UC (14.7%) and CD (21.1%) than in controls (5.0%) (P = 0.0012, 0.012 and 0.001, respectively). Interestingly, the wild genotype was found to be protective (odds ratio 0.24). The mutated allele of TLR4-Asp299Gly was more frequent in controls (6.8%) than in patients with IBD (2.9%). A phenotypic correlation of Asp299Gly-AG genotype with arthritis in UC patients was detected (P = 0.003). Regarding the NOD2 gene, the common variations studied were not polymorphic and there was no genetic association with IBD.

CONCLUSION

The TLR4-Thr399Ile variant was strongly associated with susceptibility to IBD, whereas TLR4-Asp299Gly seems to play a role in the clinical expression of UC. The rarity and non-association of NOD2 mutations with IBD may reveal a genetic characteristic of the population in our region.

Ulcerative colitis

Ulcerative colitis is a chronic inflammatory disease affecting the colon, and its incidence is rising worldwide. The pathogenesis is multifactorial, involving genetic predisposition, epithelial barrier defects, dysregulated immune responses, and environmental factors. Patients with ulcerative colitis have mucosal inflammation starting in the rectum that can extend continuously to proximal segments of the colon. Ulcerative colitis usually presents with bloody diarrhoea and is diagnosed by colonoscopy and histological findings. The aim of management is to induce and then maintain remission, defined as resolution of symptoms and endoscopic healing. Treatments for ulcerative colitis include 5-aminosalicylic acid drugs, steroids, and immunosuppressants. Some patients can require colectomy for medically refractory disease or to treat colonic neoplasia. The therapeutic armamentarium for ulcerative colitis is expanding, and the number of drugs with new targets will rapidly increase in coming years.

Toll-like receptors: promising therapeutic targets for inflammatory diseases

The health of living organisms is constantly challenged by bacterial and viral threats. The recognition of pathogenic microorganisms by diverse receptors triggers a variety of host defense mechanisms, leading to their eradication. Toll-like receptors (TLRs), which are type I transmembrane proteins, recognize specific signatures of the invading microbes and activate a cascade of downstream signals inducing the secretion of inflammatory cytokines, chemokines, and type I interferons. The TLR response not only counteracts the pathogens but also initiates and shapes the adaptive immune response. Under normal conditions, inflammation is downregulated after the removal of the pathogen and cellular debris. However, a dysfunctional TLR-mediated response maintains a chronic inflammatory state and leads to local and systemic deleterious effects in host cells and tissues. Such inappropriate TLR response has been attributed to the development and progression of multiple diseases such as cancer, autoimmune, and inflammatory diseases. In this review, we discuss the emerging role of TLRs in the pathogenesis of inflammatory diseases and how targeting of TLRs offers a promising therapeutic strategy for the prevention and treatment of various inflammatory diseases. Additionally, we highlight a number of TLR-targeting agents that are in the developmental stage or in clinical trials.

The emerging role of Toll-like receptor 4 in myocardial inflammation

Toll-like receptors (TLRs) are a family of pattern recognition receptors involved in cardiovascular diseases. Notably, numerous studies have demonstrated that TLR4 activates the expression of several of pro-inflammatory cytokine genes that play pivotal roles in myocardial inflammation, particularly myocarditis, myocardial infarction, ischemia-reperfusion injury, and heart failure. In addition, TLR4 is an emerging target for anti-inflammatory therapies. Given the significance of TLR4, it would be useful to summarize the current literature on the molecular mechanisms and roles of TLR4 in myocardial inflammation. Thus, in this review, we first introduce the basic knowledge of the TLR4 gene and describe the activation and signaling pathways of TLR4 in myocardial inflammation. Moreover, we highlight the recent progress of research on the involvement of TLR4 in myocardial inflammation. The information reviewed here may be useful to further experimental research and to increase the potential of TLR4 as a therapeutic target.

Association of NOD1, CXCL16, STAT6 and TLR4 gene polymorphisms with Malaysian patients with Crohn's disease

Crohn's disease (CD) is a prominent type of inflammatory bowel disease (IBD) that can affect any part of the gastrointestinal tract. CD is known to have higher prevalence in the Western countries, but the number of cases has been increasing in the past decades in Asia, including Malaysia. Therefore, there is a need to investigate the underlining causes of CD that may shed light on its prevention and treatment. In this study, genetic polymorphisms in NOD1 (rs2075820), CXCL16 (rs2277680), STAT6 (rs324015) and TLR4 (rs4986791) genes were examined in a total of 335 individuals (85 CD patients and 250 healthy controls) with PCR-RFLP approach. There was no significant association observed between NOD1 rs2075820 and STAT6 rs324015 with the onset of CD in the studied cohort. However, the G allele of CXCL16 rs2277680 was found to have a weak association with CD patients (P = 0.0482; OR = 1.4310). The TLR4 rs4986791 was also significantly associated to CD. Both the homozygous C genotype (P = 0.0029; OR = 0.3611) and C allele (P = 0.0069; OR = 0.4369) were observed to confer protection against CD. On the other hand, the heterozygous C/T genotype was a risk genotype (P = 0.0015; OR = 3.1392). Further ethnic-stratified analysis showed that the significant associations in CXCL16 rs2277680 and TLR4 rs4986791 were accounted by the Malay cohort. In conclusion, the present study reported two CD-predisposing loci in the Malay CD patients. However, these loci were not associated to the onset of CD in Chinese and Indian patients.

Association of inflammatory cytokine gene polymorphisms with inflammatory bowel disease in a Moroccan cohort

The purpose of this study was to investigate whether common variants in inflammatory and immune response genes influence inflammatory bowel disease (IBD) risk among Moroccan patients. Using a candidate gene approach, 10 single-nucleotide polymorphisms mapping on six genes (MIF_rs755622, TNFA_rs1800629, IL6_rs2069840, IL6R_rs2228145, IL6ST_rs2228044, IL17A (rs2275913, rs4711998, rs7747909, rs8193036, rs3819024)) were assessed in 510 subjects grouped in 199 IBD and 311 healthy controls. Genotyping was performed with the TaqMan allelic discrimination technology. The results were analyzed using PLINK software. The frequency of allele A for TNFA rs1800629 was significantly higher in ulcerative colitis (UC) patients compared with controls (30.16 vs 16.72%; P=0.0005; odds ratio (OR)=2.15; 95% confidence interval (CI)=1.39-3.32). Statistically significant association to UC was also found under dominant AA+AG vs GG (OR=1.85, 95% CI=1.07-3.21; P=0.02) and recessive models (OR=8.38; 95% CI=2.86-24.53; P=0.0001). In the same way, an association of TNFA rs1800629 variant was observed with IBD under recessive model AA vs AG+GG (OR=4.10; 95% CI=1.56-10.76; P=0.004). No evidence of significant associations was found for the remaining investigated polymorphisms. Our data suggest that TNFA gene promoter polymorphism participates in determining IBD susceptibility in Moroccan patients.

Genetic Polymorphisms of Multidrug Resistance Gene-1 (MDR1/ABCB1) and Glutathione S-Transferase Gene and the Risk of Inflammatory Bowel Disease among Moroccan Patients

Inflammatory bowel diseases (IBD) are multifactorial disorders resulting from environmental and genetic factors. Polymorphisms in MDR1 and GSTs genes might explain individual differences in susceptibility to IBD. We carried out a case-control study to examine the association of MDR1 (C1236T and C3435T), GSTT1, and GSTM1 polymorphisms with the risk of IBD. Subjects were genotyped using PCR-RFLP for MDR1 gene and multiplex PCR for GSTT1 and GSTM1. Meta-analysis was performed to test the association of variant allele carriage with IBD risk. We report that GSTT1 null genotype is significantly associated with the risk of CD (OR: 2.5, CI: 1.2–5, P = 0.013) and UC (OR: 3.5, CI: 1.5–8.5, P = 0.004) and can influence Crohn's disease behavior. The interaction between GSTT1 and GSTM1 genes showed that the combined null genotypes were associated with the risk of UC (OR: 3.1, CI: 1.1–9, P = 0.049). Furthermore, when compared to combined 1236CC/CT genotypes, the 1236TT genotype of MDR1 gene was associated with the risk of UC (OR: 3.7, CI: 1.3–10.7, P = 0.03). Meta-analysis demonstrated significantly higher frequencies of 3435T carriage in IBD patients. Our results show that GSTT1 null and MDR1 polymorphisms could play a role in susceptibility to IBD.