Rapid and inexpensive real-time PCR for genotyping functional polymorphisms within the Toll-like receptor -2, -4, and -9 genes

Association of Single Nucleotide Polymorphisms from Angiogenesis-Related Genes, ANGPT2, TLR2 and TLR9, with Spontaneous Preterm Labor

In this study, we hypothesized that the changes localized at angiopoietin-2 (ANGPT2), granulocyte-macrophage colony-stimulating factor (CSF2), fms-related tyrosine kinase 1 (FLT1) and toll-like receptor (TLR) 2, TLR6 and TLR9 genes were associated with spontaneous preterm labor (PTL), as well as with possible genetic alterations on PTL-related coagulation. This case-control genetic association study aimed to identify single nucleotide polymorphisms (SNPs) for the aforementioned genes, which are correlated with genetic risk or protection against PTL in Polish women. The study was conducted in 320 patients treated between 2016 and 2020, including 160 women with PTL and 160 term controls in labor. We found that ANGPT2 rs3020221 AA homozygotes were significantly less common in PTL cases than in controls, especially after adjusting for activated partial thromboplastin time (APTT) and platelet (PLT) parameters. TC heterozygotes for TLR2 rs3804099 were associated with PTL after correcting for anemia, vaginal bleeding, and history of threatened miscarriage or PTL. TC and CC genotypes in TLR9 rs187084 were significantly less common in women with PTL, compared to the controls, after adjusting for bleeding and gestational diabetes. For the first time, it was shown that three polymorphisms-ANGPT2 rs3020221, TLR2 rs3804099 and TLR9 rs187084 -were significantly associated with PTL, adjusted by pregnancy development influencing factors.

Toll-like receptor 9 polymorphisms and Helicobacter pylori influence gene expression and risk of gastric carcinogenesis in the Brazilian population

BACKGROUND

Toll-like receptors (TLRs) are the first line of host defense, and are involved in Helicobacter pylori (H. pylori) recognition and activation of both inflammatory and carcinogenic processes. The presence of single nucleotide polymorphisms (SNPs) in genes that activate the immune response may modulate the risk of precancerous lesions and gastric cancer (GC). Among them, Toll-like receptor 9 (TLR9) polymorphisms have emerged with a risk factor of infectious diseases and cancer, however the studies are still inconclusive.

AIM

To evaluate whether TLR9 rs5743836 and rs187084 SNPs contribute to the risk of gastric carcinogenesis, and its influence on mRNA expression.

METHODS

A case-control study was conducted to evaluate two TLR9 SNPs (TLR9-1237 TC-rs5743836 and TLR9-1486 CT-rs187084) in chronic gastritis (CG) and GC patients. A total of 609 DNA samples of peripheral blood [248 CG, 161 GC, and 200 samples from healthy individuals (C)] were genotyped by polymerase chain reaction-restriction fragment length polymorphism. All samples were tested for the H. pylori infection using Hpx1 and Hpx2 primers. Quantitative polymerase chain reaction by TaqMan^® assay was used to quantify TLR9 mRNA from fresh gastric tissues (48 GC, 26 CG, and 14 C).

RESULTS

For TLR9-1237, the TC + CC or CC genotypes were associated with a higher risk of GC than C [recessive model odds ratio (OR) = 5.01, 95% confidence interval (CI): 2.52-9.94, P < 0.0001], and the CG (recessive model OR =4.63; 95%CI: 2.44-8.79, P < 0.0001) groups. For TLR9-1486, an association between the CT + TT genotypes and increased risk of both GC (dominant model OR = 2.72, 95%CI: 1.57-4.72, P < 0.0001) and CG (dominant model OR = 1.79, 95%CI: 1.15-2.79, P = 0.0094) was observed when compared to the C group. Moreover, the presence of TLR9-1237 TC/CC + TLR9-1486 CC genotypes potentiate the risk for this neoplasm (OR = 18.57; 95%CI: 5.06-68.15, P < 0.0001). The TLR9 mRNA level was significantly higher in the GC group (RQ = 9.24, P < 0.0001) in relation to the CG group (RQ = 1.55, P = 0.0010) and normal mucosa (RQ = 1.0). When the samples were grouped according to the polymorphic genotypes and the presence of H. pylori infection, an influence of TLR9-1237 TC + CC polymorphic genotypes (P = 0.0083) and H. pylori infection (P < 0.0001) was observed on the upregulation of mRNA expression.

CONCLUSION

Our findings show that TLR9 rs5743836 and rs187084 polymorphisms are associated with a higher risk of carcinogenesis gastric, and that TLR9 mRNA levels can be modulated by TLR9-1237 TC + CC variant genotypes and H. pylori infection.

Toll-Interleukin 1 Receptor Domain-Containing Adaptor Protein 180L Single-Nucleotide Polymorphism Is Associated With Susceptibility to Recurrent Pneumococcal Lower Respiratory Tract Infections in Children

Lower respiratory tract infections (LRTI) are often caused by Streptococcus pneumoniae (Spn) and can be recurrent in 8% of children older than 2 years of age. Spn is recognized by pattern-recognition receptors (PRRs) of the innate immune system, in particular toll-like receptors (TLRs) 2 and 4. To assess whether a defect somewhere along this TLR signaling pathway increases susceptibility to recurrent pneumococcal LRTI, we conducted a prospective case-control study with 88 healthy individuals and 45 children with recurrent LRTI aged 2-5 years old. We examined cell surface expression of TLR2 and TLR4, as well as eight genetic variants of these receptors or associated co-receptors TLR1 and TLR6. Interleukin-6 production was measured after whole blood stimulation assays with specific agonists and heat-killed Spn. Our findings reveal that single-nucleotide polymorphisms within toll-interleukin 1 receptor domain-containing adaptor protein (TIRAP) alone or in combination with TLR1 N248S, TLR1 I602S, or TLR6 S249P polymorphisms contributes to various degree of susceptibility to recurrent pneumococcal LRTI in children by modulating the inflammatory response. In that respect, carriage of the TIRAP S180L heterozygous trait increases the likelihood to protect against pneumococcal LRTI, whereas children carrying the mutant homozygous TIRAP 180L polymorphism might be more likely susceptible to recurrent pneumococcal LRTI.

Functional polymorphisms of innate immunity receptors are not risk factors for the non-SBP type bacterial infections in cirrhosis

BACKGROUND & AIMS

Pattern recognition receptors (PRRs) have a key role in the innate host defense. Functional polymorphisms of various PRRs have been established to contribute to an increased susceptibility to spontaneous bacterial peritonitis (SBP). Their role in the development of cirrhosis-associated bacterial infections (BI), beyond SBP or progressive disease course related to pathological bacterial translocation (BT) remains unknown.

METHODS

Three hundred and forty-nine patients with cirrhosis were genotyped for common NOD2 (R702W, G908R and L1007PfsinsC), TLR2 (-16934T>A), and TLR4 (D299G) variants. Incidence of BIs, decompensating events and liver-related death were assessed in a 5-year follow-up observational study. Pathological BT was assessed based on the presence of antimicrobial antibodies or lipopolysaccharide-binding protein (LBP) level.

RESULTS

In patients with ascites (n = 88) only NOD2 gene variants were associated with an increased cumulative probability of SBP (76.9% ± 19.9%) compared to wild-type (30.9% ± 6.9%, P_LogRank  = .047). Individual or combined PRR genetic profiles were associated with the risk of non-SBP type BI. Advanced disease stage (HR [95% CI]: 2.11 [1.38-3.25]) and prior history of a BI episode (HR: 2.42 [1.58-3.72]) were the major clinical risk factors of a subsequent BI. The risk of a non-SBP type BI in patients with advanced disease and a prior BI was even higher (HR: 4.74 [2.68-8.39]). The frequency of antimicrobial antibodies and LBP levels did not differ between various PRR genotypes. Correspondingly, PRR genetic profile was not able to predict the long-term disease course.

CONCLUSIONS

In cirrhosis, functional polymorphisms of PRRs did not improve the identification of patients with high risk of BI beyond SBP or progressive diseases course.

Association of Toll like receptor 2 and 9 gene variants with pulmonary tuberculosis: exploration in a northern Indian population

Tuberculosis (TB) is a disease of global importance. There is an increasing recognition of the role of Toll like receptors, important pattern recognition receptors of host immune system, in determining the susceptibility or resistance to TB in various populations. In an attempt to examine the importance of Toll like receptors in immune response to Mycobacterium tuberculosis infection, we explored two variants each of TLR2 and TLR9 in a population residing in Uttar Pradesh, India. Genotyping was performed to detect -196 to -174 del polymorphism and G2258A SNP (Arg753Gln, rs5743708) in TLR2 gene and -T1237C (rs5743836) and G2848A (rs352140) SNP in TLR9 gene in patients with pulmonary TB and healthy controls. The A allele of G2848A SNP in TLR9 gene was found with a marginally higher frequency among TB patients as compared to healthy controls, suggesting that A allele at position 2848 of TLR9 gene may be associated with susceptibility to TB in North Indian population [p = 0.05, Mantel-Haenszel OR = 1.34, 95% CI (1.0-1.82)].

TLR9 -1486T/C and 2848C/T SNPs Are Associated with Human Cytomegalovirus Infection in Infants

Toll-like receptor 9 (TLR9) recognizes non-methylated viral CpG-containing DNA and serves as a pattern recognition receptor that signals the presence of human cytomegalovirus (HCMV). Here, we present the genotype distribution of single-nucleotide polymorphisms (SNPs) of the TLR9 gene in infants and the relationship between TLR9 polymorphisms and HCMV infection. Four polymorphisms (-1237T/C, rs5743836; -1486T/C, rs187084; 1174G/A, rs352139; and 2848C/T, rs352140) in the TLR9 gene were genotyped in 72 infants with symptomatic HCMV infection and 70 healthy individuals. SNP genotyping was performed by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Digested fragments were separated and identified by capillary electrophoresis. The HCMV DNA copy number was measured by a quantitative real-time PCR assay. We found an increased frequency of heterozygous genotypes TLR9 -1486T/C and 2848C/T in infants with HCMV infection compared with uninfected cases. Heterozygous variants of these two SNPs increased the risk of HCMV disease in children (P = 0.044 and P = 0.029, respectively). In infants with a mutation present in at least one allele of -1486T/C and 2848C/T SNPs, a trend towards increased risk of cytomegaly was confirmed after Bonferroni's correction for multiple testing (Pc = 0.063). The rs352139 GG genotype showed a significantly reduced relative risk for HCMV infection (Pc = 0.006). In contrast, the -1237T/C SNP was not related to viral infection. We found no evidence for linkage disequilibrium with the four examined TLR9 SNPs. The findings suggest that the TLR9 -1486T/C and 2848C/T polymorphisms could be a genetic risk factor for the development of HCMV disease.

Impaired Innate COPD Alveolar Macrophage Responses and Toll-Like Receptor-9 Polymorphisms

Background

Dysfunctional innate responses of alveolar macrophages to nontypeable Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pneumoniae contribute to morbidity in chronic obstructive pulmonary disease (COPD). Our earlier studies discovered impaired COPD alveolar macrophage responses to Toll-like receptor (TLR) ligands of nontypeable H. influenzae and provide rationale for further evaluation of TLR signaling. While the role of TLR single nucleotide polymorphisms is increasingly recognized in inflammatory diseases, TLR single nucleotide polymorphisms in COPD have only recently been explored. We hypothesized that specific TLR polymorphisms are associated with dysfunctional innate immune COPD alveolar macrophage responses and investigated polymorphisms of TLR2(Arg753Gln), TLR4(Thr399Ile; Asp299Gly), and TLR9(T1486C; T1237C).

Methods

DNA was purified from cells of 1) healthy nonsmokers (n = 20); 2) COPD ex-smokers (n = 83); 3) COPD active smokers (n = 93). DNA amplifications (polymerase chain reaction) were performed for each SNP. Alveolar macrophages from each group were incubated with nontypeable H. influenzae, M. catarrhalis and S. pneumoniae. Cytokine induction of macrophage supernatants was measured and the association with TLR single nucleotide polymorphism expression was determined.

Results

No significant inter-group differences in frequency of any TLR SNP existed. However both TLR9 single nucleotide polymorphisms were expressed in high frequency. Among COPD ex-smokers, diminished IL-8 responsiveness to nontypeable H. influenzae, M. catarrhalis and S. pneumoniae was strongly associated with carriage of TLR9(T1237C) (p = 0.02; p = 0.008; p = 0.02), but not TLR9(T1486C). Carriage of TLR9(T1237C), but not TLR9(T1486C), correlated with diminished FEV₁%predicted (p = 0.037).

Conclusion

Our results demonstrate a notable association of TLR9(T1237C) expression with dysfunctional innate alveolar macrophage responses to respiratory pathogens and with severity of COPD.

Toll-like receptor 1 N248S polymorphism affects T helper 1 cytokine production and is associated with serum immunoglobulin E levels in Taiwanese allergic patients

BACKGROUND/PURPOSE

This study was carried out to investigate whether toll-like receptor-1 (TLR1) rs4833095 (N248S) variant, common in the Taiwanese population, contributes to pathogenesis of allergy.

METHODS

TLR2/1 ligand Pam3CSK4-stimulated cytokine production in peripheral blood mononuclear cells and monocyte-derived dendritic cells of different genotypes were measured via enzyme-linked immunosorbent assay. Ninety-three Taiwanese allergic patients (with asthma, allergic rhinitis, or atopic dermatitis) and 76 controls were recruited for genotyping. Serum immunoglobulin E (IgE) levels were evaluated in 60 allergic patients.

RESULTS

The homozygous TLR1 C variant allele carrier had increased Pam3CSK4-induced tumor necrosis factor-α and interleukin-12 responses in peripheral blood mononuclear cells and monocyte-derived dendritic cells, respectively. Furthermore, although the C/C genotype was not associated with susceptibility to atopic diseases, it was correlated with lower total IgE levels in sera of allergic patients.

CONCLUSION

Our data suggest that the TLR1 N248S polymorphism might play a role in Th1/Th2 differentiation, and the determination of serum IgE levels. However, interactions with other genetic and environmental factors might be required to contribute to risk of allergic diseases in our population.

Association of NLRP3 and CARD8 genetic polymorphisms with juvenile idiopathic arthritis in a Taiwanese population

OBJECTIVES

An elevated interleukin (IL)-1β response in peripheral blood mononuclear cells (PBMCs) has been observed in systemic juvenile idiopathic arthritis (sJIA), suggesting a role for inflammasomes in the pathogenesis of JIA. We aimed to determine whether genetic polymorphisms of the NLRP3 inflammasome components confer risk for oligoarticular and polyarticular JIA in a Taiwanese population.

METHOD

A total of 118 JIA patients and 103 healthy controls were genotyped for rs4353135 OR2B11/NLRP3 and rs2043211 CARD8 polymorphisms. Clinical laboratory data and serum IL-1β of JIA patients were evaluated by medical chart review and enzyme-linked immunosorbent assay (ELISA), respectively. The production of IL-17 in lymphocytes of different genotype carriers was measured using flow cytometry.

RESULTS

The variant rs4353135 G allele carrier conferred increased risk for oligoarticular and polyarticular JIA. The G allele was also found to be associated with higher levels of clinical inflammatory markers. Moreover, G variant carriers enhanced the lymphocyte IL-17 response. The G/G genotype further increased the need for treatment with the tumour necrosis factor (TNF) inhibitor etanercept.

CONCLUSIONS

Our data indicate that the rs4353135 OR2B11/NLRP3 polymorphism might be functional in, and could contribute to, the pathophysiology of oligoarticular and polyarticular JIA in a Taiwanese population.

Attenuation of myocardial injury by HMGB1 blockade during ischemia/reperfusion is toll-like receptor 2-dependent

Genetic or pharmacological ablation of toll-like receptor 2 (TLR2) protects against myocardial ischemia/reperfusion injury (MI/R). However, the endogenous ligand responsible for TLR2 activation has not yet been detected. The objective of this study was to identify HMGB1 as an activator of TLR2 signalling during MI/R. C57BL/6 wild-type (WT) or TLR2(-/-)-mice were injected with vehicle, HMGB1, or HMGB1 BoxA one hour before myocardial ischemia (30 min) and reperfusion (24 hrs). Infarct size, cardiac troponin T, leukocyte infiltration, HMGB1 release, TLR4-, TLR9-, and RAGE-expression were quantified. HMGB1 plasma levels were measured in patients undergoing coronary artery bypass graft (CABG) surgery. HMGB1 antagonist BoxA reduced cardiomyocyte necrosis during MI/R in WT mice, accompanied by reduced leukocyte infiltration. Injection of HMGB1 did, however, not increase infarct size in WT animals. In TLR2(-/-)-hearts, neither BoxA nor HMGB1 affected infarct size. No differences in RAGE and TLR9 expression could be detected, while TLR2(-/-)-mice display increased TLR4 and HMGB1 expression. Plasma levels of HMGB1 were increased MI/R in TLR2(-/-)-mice after CABG surgery in patients carrying a TLR2 polymorphism (Arg753Gln). We here provide evidence that absence of TLR2 signalling abrogates infarct-sparing effects of HMGB1 blockade.

Possible association of Toll-like receptor 9 polymorphisms with cytokine levels and posttraumatic symptoms in individuals with various types of orthopaedic trauma: early findings

BACKGROUND

Although TLR9 polymorphisms may be associated with cytokine dysregulation, its role in regulation of cytokines due to bodily trauma or in relation to acute stress symptoms or posttraumatic stress symptoms (ASS/PTS) has not been evaluated.

AIMS

To assess serum cytokine levels and levels of ASS and PTS in relation to four common TLR9 single-nucleotide polymorphisms (SNPs) in individuals with various types of orthopaedic trauma.

METHODS

Forty-eight accident-injured individuals, aged 20-60 years were studied. Serum cytokine levels and TLR9 SNPS (1486T/C, 1237T/C, 1174G/A and 2848G/A) were assessed together with intensity of ASS and PTS symptoms.

RESULTS

Statistically significant higher serum levels of IL-12 and IL-1β (p<.05) were found in individuals heterozygous for TLR9-1237 (TC) than in individuals expressing the most common TLR9-1237 type (TT), while differences in levels of IL-6 were not significant. Also, marginally significant levels of IL-6 were found in individuals expressing the common TLR9-1174 (GG) compared with individuals homozygous (AA) or heterozygous (GA) for this SNP. They also had non-significant higher intensity of ASS symptoms. A trend of higher PTS levels in individuals expressing the most common type TLR9-1174 (GG) was found, contrary to homozygous (AA) and heterozygous individuals (GA).

CONCLUSIONS

The results of this pilot study suggest that accident-injured individuals with certain TLR9 polymorphisms express higher levels of pro-inflammatory cytokines (IL-1β, IL-6 and IL-12). The associations of TLR9 SNPSs with increased risk of ASS or PTS should be further studied in larger groups of such patients.

TLR5 stop codon polymorphism is associated with invasive aspergillosis after allogeneic stem cell transplantation

Single nucleotide polymorphisms (SNPs) have been associated with an increased incidence of invasive aspergillosis (IA) after allogeneic stem cell transplantation (allo-SCT). We analyzed 41 patients with proven/probable IA after allo-SCT for an association of SNPs, within the TLR2, TLR4, TLR5, TLR9, and NOD2/CARD15 genes, with susceptibility to IA. The control group consisted of 130 patients who had allo-SCT but did not develop IA. While no association was found for donor SNPs and the recipients' risk of IA, analysis of recipient SNPs showed a significant association between the presence of recipient TLR5-Stop SNP (1174C> T) and the incidence of IA (P = 0.004). Multivariate analysis demonstrated that the recipient TLR5-Stop SNP appeared as an independent risk factor for IA after allo-SCT. Our study suggests that TLR5 is involved in host defense against Aspergillus fumigatus, and that the recipient TLR5-Stop SNP represents a risk factor for the development of IA after allo-SCT.

Role of the functional Toll-Like receptor-9 promoter polymorphism (-1237T/C) in increased risk of end-stage renal disease: a case-control study

Inflammation induced by infectious and noninfectious triggers in the kidney may lead to end stage renal disease (ESRD). Toll-like receptor 9 (TLR-9) a receptor for CpG DNA is involved in activation of immune cells in renal disease and may contribute to chronic inflammatory disease progression through an interleukin-6 (IL-6) dependent pathway. Previous studies indicate that -1237T/C confers regulatory effects on TLR-9 transcription. To date the effect of TLR-9 polymorphisms on ESRD remains unknown. We performed a case-control study and genotyped 630 ESRD patients and 415 controls for -1237T/C, -1486T/C and 1635G/A by real-time PCR assays and assessed plasma concentration of IL-6 by ELISA. Haplotype association analysis was performed using the Haploview package. A luciferase reporter assay and real-time PCR were used to test the function of the -1237T/C promoter polymorphism. A significant association between -1237T/C in TLR-9 and ESRD was identified. The TCA, TTA and CCA haplotype of TLR-9 were associated with ESRD. ESRD patients carrying -1237TC had a higher mean plasma IL-6 level when compared with -1237TT. The TLR-9 transcriptional activity of the variant -1237CC allele is higher than the -1237TT allele. The results indicate that in a Han Chinese population the presence of the C allele of -1237T/C in the TLR-9 gene increases susceptibility towards development of ESRD. In vitro studies demonstrate that -1237T/C may be involved in the development of ESRD through transcriptional modulation of TLR-9.

A frequent Toll-like receptor 1 gene polymorphism affects NK- and T-cell IFN-γ production and is associated with Helicobacter pylori-induced gastric disease

BACKGROUND

Helicobacter pylori infects approximately 50% of the world population. Among the infected individuals, only 10-20% develop peptic ulcers and <3% progress to gastric cancer (GC). Th1-predominant immune responses have been suggested to underlie H. pylori-induced gastric diseases. However, the reason for a strong inter-individual variation of susceptibility and course of the disease is currently far from being understood. It has been shown that H. pylori stimulates the host's Toll-like receptor (TLR) 2/1 complex. Furthermore, the single nucleotide polymorphism (SNP) I602S of TLR1 alters the inflammatory cytokine response of monocytes. Therefore, we hypothesized an association of this TLR1 SNP with H. pylori-mediated gastric pathologies.

MATERIALS AND METHODS

Subjects with different TLR1 genotypes were analyzed for their IFN-γ response of NK- and T-cells. We further genotyped 548 patients with gastric diseases for this SNP and compared patients with gastritis with those having ulcer, and patients with high-risk gastritis versus patients with GC.

RESULTS

Homozygous 602S allele carriers exhibited impaired in vitro IFN-γ responses to the TLR2/1 agonist Pam(3) CSK(4). The TLR1 I602S SNP is significantly associated with GC (p = .002) and gastric ulcer (p = .051). Odds ratios showed significantly reduced risk regarding GC and peptic ulcer for the homozygous mutated genotype. The odds ratios were 0.4 (95% CI, 0.22-0.72) and 0.588 (95% CI, 0.35-1.00), respectively.

CONCLUSION

In conclusion, our results suggest that the nonfunctional TLR1 602S/S genotype is associated with a reduced risk of H. pylori-induced gastric diseases, probably via diminished Th1 responses.

Innate immunity gene single nucleotide polymorphisms and otitis media

OBJECTIVE

Toll-like receptors (TLR) activate the innate immune system. Single nucleotide polymorphisms (SNPs) in TLR genes are linked to increased susceptibility to infections. TLR4-deficient mice have increased incidence and duration of otitis media. We hypothesize that SNPs in TLR genes are more common in otitis-prone children than in children without a history of otitis media.

METHODS

Cases (n=70) included children undergoing surgery for otitis media. Control subjects (n=70) included children undergoing surgery for non-otologic indication. Genomic DNA was extracted from blood samples. RT-PCR genotyping was performed for TLR2 (rs5743708), TLR4 (rs4986790 and rs4986791), TLR9 (rs5743836 & rs187084), and CD14 (rs2569190).

RESULTS

There were no significant differences between the groups in family history, day care, smoke exposure, allergies or prevalence of the SNPs. The most common pre-op diagnosis in control subjects was obstructive sleep apnea (OSA).

CONCLUSIONS

TLR2, TLR4, TLR9 and CD14 gene SNPs were not more prevalent in otitis-prone children.

Association of TLR3-hyporesponsiveness and functional TLR3 L412F polymorphism with recurrent herpes labialis

HSV-1 persistently infects almost 90% of our population; however, only 30% of the infected subjects suffer from recurrent herpes lesions, most frequently herpes labialis (HL). We hypothesized that variations in toll-like receptor (TLR) functions might contribute to HL susceptibility. In our study, the TLR-2/1,-3, and -7/8 responses of immune cell subsets derived from asymptomatic HSV-1 carriers were compared with responses of subjects with HL history. Remarkably, natural killer (NK) cells isolated from HL subjects showed significantly lower IFN-γ responses selectively to the TLR3 agonist poly(I:C). Furthermore, the TLR3 L412F genetic polymorphism was found to reduce NK cell TLR3-responsiveness and is associated with susceptibility to recurrent HL. The TLR3 response detected in HL total peripheral blood mononuclear cells (PBMCs), however, was not impaired, indicating restoration of NK cell TLR3-deficiency through co-stimulatory functions. In conclusion, our results suggest that decreased TLR3 response of NK cells is associated with HL susceptibility; and potentially explain why symptomatic outbreak of HL usually occurs after stress or prolonged UV light exposure, when host co-stimulatory functions are disturbed.

Mannose-binding lectin and Toll-like receptor polymorphisms and Chagas disease in Chile

Mannose-binding lectin (MBL) and Toll-like receptor (TLR) polymorphisms may influence susceptibility and manifestation of Trypanosoma cruzi infection. In northern Chile, we examined 61 asymptomatic patients with chronic Chagas disease (CD), 64 patients with chronic Chagas cardiomyopathy (CCC), and 45 healthy individuals. Low-producer MBL2*B genotypes were more common in CD patients (48%) than healthy individuals (31%; adjusted odds ratio = 2.3, 95% confidence interval = 1.01-5.4, P = 0.047) but did not differ with manifestation. In contrast, the heterozygous Toll-like receptor 4 (TLR4)-deficiency genotype D299G/T399I occurred more frequently in asymptomatic (14.8%) than CCC patients (3.1%; P = 0.02). TLR1-I602S, TLR2-R753Q, TLR6-S249P, and MAL/TIRAP-S180L did not associate with CD or CCC. These findings support the complement system to be involved in defense against Trypanosoma cruzi infection and indicate that curbed TLR4 activation might be beneficial in preventing CCC.

Homozygosity for the toll-like receptor 2 R753Q single-nucleotide polymorphism is a risk factor for cytomegalovirus disease after liver transplantation

Immunity against cytomegalovirus (CMV) is initiated after its recognition by Toll-like receptor 2 (TLR2). We assessed the association between a single-nucleotide polymorphism (SNP) that impairs TLR2 function and CMV disease in a cohort of 737 liver recipients. Ninety-two of 737 patients (7.1%, 10.9%, 12.3%, and 12.5% by 3, 6, 12, and 24 months, respectively) developed CMV disease. Kaplan-Meier estimation demonstrated an association between TLR2 R753Q SNP homozygosity and CMV disease (P = .044), especially tissue-invasive CMV disease (P = .001). A multivariate Cox proportional hazard model that accounted for other significant predictors demonstrated a significant association between TLR2 R753Q SNP homozygosity and tissue-invasive CMV disease (hazard ratio, 3.407; 95% confidence interval, 1.518-7.644; P = .0029). In conclusion, homozygosity for TLR2 R753Q SNP is a marker for CMV disease risk, especially for tissue-invasive disease, after liver transplantation. This observation supports the critical role of TLR2 in the pathogenesis of CMV disease in humans.

The (-1486T/C) promoter polymorphism of the TLR-9 gene is associated with end-stage knee osteoarthritis in a Chinese population

Based on the recent observation that Toll-like receptors (TLRs) may be involved in the pathogenesis of osteoarthritis (OA) we explored the possibility that human TLR gene polymorphisms are associated with OA. Two separate populations were studied in a two-stage case-control study with a total of 503 OA patients and 428 healthy controls. The TLR-2, TLR-4, and TLR-9 genotypes were assessed by real-time polymerase chain reaction. Our data demonstrated a lack of association among TLR-2, TLR-4, and TLR-9 (T-1237C) polymorphisms and the risk of developing OA in both stages of the study. T-1486C was significantly associated with OA in both populations with G1635A of TLR-9 gene was found to be significantly associated with OA when the two populations were combined. Stratifying the samples by K-L score there were significant differences in the genotype of the TLR-9 T-1486C and G1635A between OA of the knee grade 4 and controls. In haplotype analyses, the haplotype TTG and TTA revealed higher risk of OA and TCA confers a lower risk of OA in combined population. The present results demonstrate that TLR-9 polymorphisms, in particular T-1486C is significantly associated with OA. TLR-9 gene polymorphisms may play a role in the etiology of knee OA.

The T-1237C polymorphism of the Toll-like receptor-9 gene is associated with chronic kidney disease in a Han Chinese population

Chronic kidney disease (CKD) is increasingly recognized as a global public health problem. As inflammatory processes and genetic factors are involved in the pathogenesis of CKD, we have investigated the potential genetic contribution of Toll-like receptor (TLR) gene polymorphisms in CKD. In a case-control association study, 149 CKD patients and 429 healthy controls were genotyped by real-time polymerase chain reaction. CKD patients were defined as kidney damage (albuminuria, proteinuria or hematuria) or glomerular filtration rate < 60 ml/min/1.73 m(2) for 3 months or more. Single nucleotide polymorphisms (SNPs) at TLR-2 G2408A, TLR-4 A12874G and C13174T, and TLR-9 T-1237C, T-1486C, and G1635A were assessed, and linkage disequilibrium calculations and haplotype association analysis were undertaken. The functions of TLR-9 have been documented to recognize the viral and bacterial CpG DNA sequences, whereas detects microbe-derived peptidoglycan and lipopeptides and TLR-4 binds lipopolysaccharides. SNPs within the TLR genes may influence promoter activity, mRNA conformation and subcellular localization, and/or protein structure and function. Our results show that only the TLR-9 T-1237C and G1635A gene polymorphisms demonstrate an association with CKD (p = 0.002 and p = 0.04, respectively). The TLR-9 TCA haplotype at T-1237C, T-1486C, and G1635A was associated with a lower risk of CKD, whereas the TTA haplotype was associated with a higher risk of CKD. In the Han Chinese population, those who carry the C and A alleles at SNPs T-1237C and G1635A in the TLR-9 gene appear to be more susceptible to the development of CKD.

Genetic variation of TLR4 influences immunoendocrine stress response: an observational study in cardiac surgical patients

Introduction

Systemic inflammation (for example, following surgery) involves Toll-like receptor (TLR) signaling and leads to an endocrine stress response. This study aims to investigate a possible influence of TLR2 and TLR4 single nucleotide polymorphisms (SNPs) on perioperative adrenocorticotropic hormone (ACTH) and cortisol regulation in serum of cardiac surgical patients. To investigate the link to systemic inflammation in this context, we additionally measured 10 different cytokines in the serum.

Methods

A total of 338 patients admitted for elective cardiac surgery were included in this prospective observational clinical cohort study. Genomic DNA of patients was screened for TLR2 and TLR4 SNPs. Serum concentrations of ACTH, cortisol, interferon (IFN)-γ, interleukin (IL)-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, tumor necrosis factor (TNF)-α and granulocyte macrophage-colony stimulating factor (GM-CSF) were determined before surgery, immediately post surgery and on the first postoperative day.

Results

Thirteen patients were identified as TLR2 SNP carriers, 51 as TLR4 SNP carriers and 274 patients as non-carriers. Basal levels of ACTH, cortisol and cytokines did not differ among groups. In all three groups a significant, transient perioperative rise of cortisol could be observed. However, only in the non-carrier group this was accompanied by a significant ACTH rise. TLR4 SNP carriers had significant lower ACTH levels compared to non-carriers (mean (95% confidence intervals)) non-carriers: 201.9 (187.7 to 216.1) pg/ml; TLR4 SNP carriers: 149.9 (118.4 to 181.5) pg/ml; TLR2 SNP carriers: 176.4 ((110.5 to 242.3) pg/ml). Compared to non-carriers, TLR4 SNP carriers showed significant lower serum IL-8, IL-10 and GM-CSF peaks (mean (95% confidence intervals)): IL-8: non-carriers: 42.6 (36.7 to 48.5) pg/ml, TLR4 SNP carriers: 23.7 (10.7 to 36.8) pg/ml; IL-10: non-carriers: 83.8 (70.3 to 97.4) pg/ml, TLR4 SNP carriers: 54.2 (24.1 to 84.2) pg/ml; GM-CSF: non-carriers: 33.0 (27.8 to 38.3) pg/ml, TLR4 SNP carriers: 20.2 (8.6 to 31.8) pg/ml). No significant changes over time or between the groups were found for the other cytokines.

Conclusions

Regulation of the immunoendocrine stress response during systemic inflammation is influenced by the presence of a TLR4 SNP. Cardiac surgical patients carrying this genotype showed decreased serum concentrations of ACTH, IL-8, IL-10 and GM-CSF. This finding might have impact on interpreting previous and designing future trials on diagnosing and modulating immunoendocrine dysregulation (for example, adrenal insufficiency) during systemic inflammation and sepsis.

Influence of genetic variations in TLR4 and TIRAP/Mal on the course of sepsis and pneumonia and cytokine release: an observational study in three cohorts

Introduction

It has been proposed that individual genetic variation contributes to the course of severe infections and sepsis. Recent studies of single nucleotide polymorphisms (SNPs) within the endotoxin receptor and its signaling system showed an association with the risk of disease development. This study aims to examine the response associated with genetic variations of TLR4, the receptor for bacterial LPS, and a central intracellular signal transducer (TIRAP/Mal) on cytokine release and for susceptibility and course of severe hospital acquired infections in distinct patient populations.

Methods

Three intensive care units in tertiary care university hospitals in Greece and Germany participated. 375 and 415 postoperative patients and 159 patients with ventilator associated pneumonia (VAP) were included. TLR4 and TIRAP/Mal polymorphisms in 375 general surgical patients were associated with risk of infection, clinical course and outcome. In two prospective studies, 415 patients following cardiac surgery and 159 patients with newly diagnosed VAP predominantly caused by Gram-negative bacteria were studied for cytokine levels in-vivo and after ex-vivo monocyte stimulation and clinical course.

Results

Patients simultaneously carrying polymorphisms in TIRAP/Mal and TLR4 and patients homozygous for the TIRAP/Mal SNP had a significantly higher risk of severe infections after surgery (odds ratio (OR) 5.5; confidence interval (CI): 1.34 - 22.64; P = 0.02 and OR: 7.3; CI: 1.89 - 28.50; P < 0.01 respectively). Additionally we found significantly lower circulating cytokine levels in double-mutant individuals with ventilator associated pneumonia and reduced cytokine production in an ex-vivo monocyte stimulation assay, but this difference was not apparent in TIRAP/Mal-homozygous patients. In cardiac surgery patients without infection, the cytokine release profiles were not changed when comparing different genotypes.

Conclusions

Carriers of mutations in sequential components of the TLR signaling system may have an increased risk for severe infections. Patients with this genotype showed a decrease in cytokine release when infected which was not apparent in patients with sterile inflammation following cardiac surgery.

A real-time PCR assay for the simultaneous detection of functional N284I and L412F polymorphisms in the human Toll-like receptor 3 gene

Toll-like receptors (TLR) serve important roles in immunity against microbial pathogens, and TLR3 plays a critical role in the recognition of double-stranded RNA derived from viruses. Two specific single nucleotide polymorphisms (SNP) in the human TLR3 gene, A851T and C1234T, which result in amino acid substitutions, N284I and L412F, respectively, have been described to result in impaired receptor signaling and function in an in vitro model. Hence, an assay that could simultaneously detect these two functional TLR3 SNPs could facilitate studies into their role in the pathogenesis of human viral diseases and serve as a tool to screen viral disease predisposition. Therefore, we developed a real-time PCR assay based on a LightCycler format for simultaneous detection of A851T and C1234T SNPs within the TLR3 gene. This relatively low-cost PCR assay is proposed as a novel tool in the study of TLR3 and its role in viral disease.

Association of the toll-like receptor 2 A-16934T promoter polymorphism with severe atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disease with a multifactorial pathogenesis and increasing incidence in the Western world. A genetically determined defective function of pattern recognition receptors such as toll-like receptors (TLRs) has been proposed as a candidate mechanism in the pathogenesis of AD.

AIM

To study the impact of genetic predisposition of five genes encoding for pattern recognition-related molecules for the phenotype of AD.

METHODS

We examined nine different single-nucleotide polymorphism (SNP) frequencies in the genes encoding TLR1, -2, -4, -9 and the adapter molecule TIRAP by PCR with subsequent melting curve analysis in a case/control cohort of 136 adult AD patients and 129 age and gender matched non-atopic, healthy individuals. TLR2-expression and -function in cells from genotyped individuals were analysed.

RESULTS

For the SNPs examined, similar genotype frequencies were found in both groups. In a subgroup of patients suffering from severe AD (SCORAD >50), a significantly increased representation of the A-allele in position -16934 of the tlr2 gene was present (P = 0.004). Constitutive tlr2 mRNA expression in peripheral monocytes was independent of this tlr2 promoter SNP. Stimulation assays indicated that IL-6, but not TNF-alpha secretion following TLR2 stimulation is reduced in homozygous tlr2-16934-A allele carriers.

CONCLUSION

These data indicate that TLR2 is relevant for the phenotype of severe AD in adults.

Improved outcome of hematopoietic SCT in patients with homozygous gene variant of Toll-like receptor 9

Toll-like receptor 9 (TLR9) is part of the innate immune system, which is activated by CpG oligonucleotides (ODNs) and produces potent Th1-type innate and adaptive immune responses. It is reported that TLR9 gene variants, T1486C and T1237C, are associated with a reduced TLR9 expression compared with the wild-type gene. In two cohort analyses, we evaluated the influence of these gene variants on the outcome of transplant in 413 patients and donors. A retrospective analysis of the first cohort (n=293) showed that the homozygous CC gene variant of TLR9 (1486) compared with TC/TT gene variants was significantly associated with a markedly improved 5-year TRM (11.7 versus 36.4%, P<0.003), 5-year OS (86.1 vs 48.3%, P<0.001) and a lower relapse rate (13.2 vs 33.3%, P<0.007), whereas the occurrence of acute GVHD was not different. A prospectively performed analysis of the second cohort (n=120) and multivariate analyses confirmed the influence of the CC gene variant on these end points. Compared with patients with TC/TT gene at position 1486 of TLR9, patients with the homozygous CC gene variant had a lower TLR9 mRNA expression and a delayed T-cell immune reconstitution after transplant, which might prevent them from overwhelming immune responses as sepsis or systemic inflammatory response syndrome (SIRS) associated with an increased TRM. In vitro studies using CpG-rich ODNs showed an upregulation of TLR9 expression in cell lines with CC gene variant, but not in cell lines with wild-type gene.

Toll-like receptors and CD14 genes polymorphisms and susceptibility to asthma in Tunisian children

Many studies have shown the implication of CD14 and toll-like receptors (TLRs) 2, 4 and 9 in the pathogenesis of asthma or atopy. To evaluate the association of CD14 and TLRs gene polymorphisms with asthma or atopy, 210 asthmatic children, 224 controls and 80 families were enrolled in this study. Six single nucleotide polymorphisms TLR2 (+2408 G-->A), TLR4 (+1196 C-->T), TLR4 (+896 A-->G), TLR9 (-1237 T-->C), TLR9 (-1486 T-->C) and CD14 (-159 C-->T) were genotyped using polymerase chain reaction followed by restriction fragment length polymorphism in the case-control and family study. The -1237C allele in TLR9 gene polymorphisms was associated with increased risk of asthma [odds ratio 1.53, 95% confidence interval (1.03-2.27)], although no statistically significant differences in allele or genotype frequencies of four other TLRs polymorphisms were evident between the asthmatic and control groups. The CD14 -159 C allele was found to be significantly higher in the asthmatic group when compared with controls (P=0.0006<0.05). Transmission disequilibrium test of 80 asthmatic families showed significant transmission of the -159 C allele in the CD14 gene to asthma-affected offspring. It was concluded that TLR9 and CD14 gene polymorphisms may contribute to an inherited predisposition to asthma in Tunisian children.

Association between toll-like receptor polymorphisms and the outcome of liver transplantation for chronic hepatitis C virus

BACKGROUND

Experimental models suggest that immune cells recognize hepatitis C virus (HCV) through toll-like receptor (TLR)-2 and TLR4. We assessed the association between the single nucleotide polymorphism in genes that encode for these receptors and the outcome of liver transplantation for chronic HCV.

METHODS

A historical cohort of 92 liver transplant patients with chronic HCV were screened for TLR2 Arg753Gln and TLR4 Asp299Gly and Thr399Ile polymorphisms. The results were correlated with the predefined composite primary outcome of cirrhosis, retransplantation, and death. Statistical analysis was performed using Kaplan-Meier estimation and Cox proportional hazard model.

RESULTS

The mean patient age was 49+/-9 years. Sixty percent were male and 84% were white. Twelve (13%) patients had TLR2 Arg753Gln and 32 (35%) had TLR4 Asp299Gly and/or Thr399Ile polymorphism. During the mean follow-up period of 32 months after liver transplantation, the composite primary outcome occurred in 19 (24%) of 80 patients without TLR2 polymorphism, one (14%) of seven patients with heterozygous TLR2 polymorphism, and in all five (100%) patients with homozygous TLR2 polymorphism (P=0.0007). Time-to-event analysis showed a significant association between homozygous TLR2 polymorphism and the primary outcome (P<0.0001). After adjusting for donor age and azathioprine use, homozygous TLR2 mutation (RR 5.20 [1.65-13.9]; P=0.007) remained associated with the primary outcome. TLR4 polymorphisms were not associated with primary outcome.

CONCLUSION

Homozygous TLR2 Arg753Gln polymorphism is associated with allograft failure and mortality after liver transplantation for chronic HCV. The potential clinical relevance of this observation should encourage studies to assess its biologic mechanism.

Study of disease-relevant polymorphisms in the TLR4 and TLR9 genes: A novel method applied to the analysis of the Portuguese population

Toll-like receptors (TLRs) are cellular receptors that mediate recognition of microbial challenges and the subsequent inflammatory response. Genetic variations within these inflammation-associated genes may alter host-pathogen defence mechanisms affecting susceptibility towards infectious diseases. Taking into account the significance of these genes, we developed a simple and rapid method based in the bi-directional PCR amplification of specific alleles (Bi-PASA) for genotyping known sequence variants in TLR4 (Asp299Gly and Thr399Ile) and TLR9 (T-1237C) genes. This method allows genotype determination in a single reaction and is amenable to large-scale analysis. We used Bi-PASA to characterize the distribution of these polymorphisms in the Portuguese population. A total of 388 randomly selected blood donors of Portuguese origin (203 females and 185 males) were genotyped and allele frequencies were determined. Among the tested individuals, 11.1% and 10.8% were heterozygous for Asp299Gly and Thr399Ile, respectively. In what concerns the T-1237C variation in TLR9, the variant allele was present in 19.4% of the individuals tested. Besides confirming the usefulness of the Bi-PASA in polymorphism analysis, the data presented provide valuable information on TLR polymorphisms in the Portuguese population that can be used to stratify risk patients with increased susceptibility to infection.

Cutting edge: A common polymorphism impairs cell surface trafficking and functional responses of TLR1 but protects against leprosy

TLRs constitute an essential family of pattern recognition molecules that, through direct recognition of conserved microbial components, initiate inflammatory responses following infection. In this role, TLR1 enables host responses to a variety of bacteria, including pathogenic species of mycobacteria. In this study, we report that I602S, a common single nucleotide polymorphism within TLR1, is associated with aberrant trafficking of the receptor to the cell surface and diminished responses of blood monocytes to bacterial agonists. When expressed in heterologous systems, the TLR1 602S variant, but not the TLR1 602I variant, exhibits the expected deficiencies in trafficking and responsiveness. Among white Europeans, the 602S allele represents the most common single nucleotide polymorphism affecting TLR function identified to date. Surprisingly, the 602S allele is associated with a decreased incidence of leprosy, suggesting that Mycobacterium leprae subverts the TLR system as a mechanism of immune evasion.

Relationship between Toll-like receptor 2 polymorphism and cytomegalovirus disease after liver transplantation

BACKGROUND

Experimental data suggest that cytomegalovirus (CMV) initiates innate immunity through the activation of Toll-like receptor 2 (TLR2). To assess the clinical relevance of this experimental observation, we assessed the association between the specific single-nucleotide polymorphism that results in the substitution of arginine for glutamine in position 753 of TLR2 (the TLR2 Arg753Gln polymorphism) and CMV replication and disease after liver transplantation.

METHODS

Ninety-two liver transplant recipients with chronic hepatitis C were screened for the presence of the TLR2 Arg753Gln polymorphism. CMV load was determined in serially collected blood samples using CMV DNA polymerase chain reaction. Kaplan-Meier estimation and univariable and multivariable stepwise Cox proportional hazard models were used to assess associations.

RESULTS

The degree of CMV replication, as measured by CMV load, was significantly higher in patients who were homozygous (mean maximum viral load, 37,059 copies/mL) and heterozygous (mean maximum viral load, 29,718 copies/mL) for this polymorphism, compared with patients without the TLR2 Arg753Gln polymorphism (mean maximum viral load, 3252 copies/mL; P=.003). Kaplan-Meier survival analysis demonstrated an association between being homozygous for the TLR2 Arg753Gln polymorphism and CMV disease (P=.04). A multivariate Cox proportional hazard model demonstrated a trend towards a higher risk of CMV disease among patients who were homozygous for the TLR2 Arg753Gln polymorphism (hazard ratio, 1.91 [95% confidence interval, 0.91-3.40]; P=.08) after adjusting for patient age, CMV serostatus, and allograft rejection.

CONCLUSIONS

TLR2 Arg753Gln polymorphism is possibly associated with CMV replication and disease after liver transplantation. This novel clinical observation supports the potential role of TLR2 in the immunologic control of CMV infection in humans.

Genetic polymorphisms of NOD1 and IL-8, but not polymorphisms of TLR4 genes, are associated with Helicobacter pylori-induced duodenal ulcer and gastritis

BACKGROUND

Intracellular pathogen receptor NOD1 is involved in the epithelial cell sensing Helicobacter pylori, which results in a considerable interleukin (IL)-8 production. The aim of this study was to evaluate the relationship between NOD1 and IL-8 genetic polymorphisms and the development of H. pylori-induced gastritis and duodenal ulcer (DU), as compared with TLR4 polymorphisms.

MATERIALS AND METHODS

Eighty-five patients with DU and 135 patients with gastritis were enrolled in the study. Seventy-five serologically H. pylori-positive subjects without gastric or duodenal symptoms served as controls. The G796A (E266K) NOD1 polymorphism was determined by restriction fragment length polymorphism, and the -251 IL-8 polymorphism by amplification refractory mutation system method. The TLR4 (ASP/299/Gly and Thr/399/Ile) gene polymorphisms were examined by melting point analysis.

RESULTS

AA homozygote mutant variants of NOD1 were detected in 20% of the H. pylori-positive patients with DU versus 7% of H. pylori-positive patients with gastritis and versus 6% of the H. pylori-positive healthy controls. The IL-8 heterozygote mutant variant was detected with a significantly higher frequency among the DU patients and those with gastritis than among the H. pylori-positive controls. However, no significant correlation concerning the frequency of the TLR4 gene polymorphism could be revealed between any group of patients and the controls.

CONCLUSION

E266K CARD4/NOD1, but not the TLR4 gene polymorphism increases the risk of peptic ulceration in H. pylori-positive patients. The -251 IL-8 polymorphism was significantly associated with either gastritis or DU in H. pylori-infected subjects. Host factors including intracellular pathogen receptors and IL-8 production play an important role in H. pylori-induced gastric mucosal damage.

Disease association of the interleukin-18 promoter polymorphisms in Taiwan Chinese systemic lupus erythematosus patients

Interleukin (IL)-18, an important mediator of innate and adaptive immunity, plays multiple roles in chronic inflammation, in autoimmune diseases, in a variety of cancers and in number of infectious diseases. IL-18 promoter polymorphisms have been also noted associated with various inflammatory diseases. We investigated the association of IL-18 promoter polymorphisms (-656T/G, -607A/C and -137C/G) with systemic lupus erythematosus (SLE) in Taiwan Chinese patients and controls. Six haplotypes (hts) were identified from the three promoter polymorphisms. The genotype distribution of the ht1 (GCC), ht2 (TAC), ht4 (GAC) and ht5 (TCC) were different in patients and controls (P<0.002). Moreover, the haplotype and genotype frequencies of ht1 were significantly increased in patients with discoid rash (P=0.045, odds ratio (OR): 2.01, 95% confidence interval (CI): 1.01-4.00; P=0.027, OR: 5.13, 95% CI: 1.41-18.68). In addition, the homozygous genotype ht1/ht1 was significant increased in patients with serositis (P=0.015, OR: 9.78, 95% CI: 1.55-61.73). These observations suggest that the three promoter polymorphisms contribute to the genetic background of SLE pathogenesis.

Polymorphism in the IL-8 gene, but not in the TLR4 gene, increases the severity of acute pancreatitis

BACKGROUND/AIM

Activated granulocytes and inflammatory mediators of the innate immune response play fundamental roles in the pathogenesis of acute pancreatitis. We studied whether polymorphisms of interleukin-8 (IL-8) and Toll-like receptor 4 (TLR4) genes correlate with the severity of acute pancreatitis.

METHODS

Patients with acute pancreatitis (n = 92) were grouped according to the severity of the disease on the basis of the Ranson scores. Healthy blood donors (n = 200) served as controls. The IL-8 -251 gene polymorphism was analyzed by amplification-refractory mutation system; the single-nucleotide polymorphisms (Asp299Gly and Thr399Ile) of TLR4 were investigated by using a real-time polymerase chain reaction method with melting point analysis.

RESULTS

The IL-8 A/T heterozygote mutant variants were detected with a significantly higher frequency among the patients with severe pancreatitis than among the healthy blood donors (60 vs. 42%; p = 0.0264, odds ratio = 2.071, 95% confidence interval = 1.101-3.896), while the frequency of the normal allelic genotype (TT) was higher among the patients with mild pancreatitis than in the group with severe pancreatitis (35 vs. 16%; p = 0.051, odds ratio = 2.917, 95% confidence interval = 1.089-7.811). There was no significant correlation between TLR4 polymorphisms and the acute pancreatitis itself, but nonsignificantly increased frequencies of Asp299Gly and Thr399Ile heterozygotes among patients with severe infected pancreatic necrosis could be observed relative to the patients with mild pancreatitis.

CONCLUSIONS

Determination of the frequency of IL-8 polymorphism in acute pancreatitis may be informative and may provide further evidence concerning the role of IL-8 in the severe form of this disease. The possible role of TLR4 polymorphism in the outcome of severe acute pancreatitis requires further investigations in a larger series of patients.

Pre- and postoperative cytokine release after in vitro whole blood lipopolysaccharide stimulation and frequent toll-like receptor 4 polymorphisms

In a prospective cohort study, we examined 62 patients undergoing major surgical cancer therapy for Toll-like receptor 4 (TLR4) gene polymorphisms (Asp299Gly and Thr399Ile) and their influence on cytokine levels pre- and postoperatively, as well as cytokine levels after whole blood lipopolysaccharide (LPS) stimulation. Incidence of the TLR4 gene single nucleotide polymorphism (SNP) Asp299Gly/Thr399Ile was 14.5% (9/62). Overall, mortality was unaffected by the TLR4 SNP. Preoperative cytokine levels were low, with most of the values of cytokines being below the detection levels. After preoperative stimulation of whole blood with 50 pg/mL LPS, TNF-alpha and IL-6 values increased significantly in both groups. However, no significant influence was detectable between the TLR4 SNP group and the wild type group (WT group). Postoperative IL-6 levels, but not TNF-alpha levels, were significantly increased in both groups. Postoperative LPS stimulation resulted in significantly lower TNF-alpha levels compared with preoperative induction, with a more than 2.3-fold decrease in the TLR4 SNP group: 310.83 pg/mL (SD: 117.53) to 134.08 pg/mL (SD: 91.49; P < 0.001) and a 2.2-fold decrease in the WT group: 422.97 pg/mL (SD: 662.57) to 191.68 pg/mL (SD:147.26; P = 0.031). IL-6 levels after stimulation were comparably decreased with similarly no significant difference between the two groups. We conclude that the TLR4 polymorphism Asp299Gly/Thr399Ile has no influence on cytokine release after LPS stimulation in the early and late course after major surgery. The LPS adaptation effect of cytokine release after surgery is furthermore not affected by the presence of the TLR4 polymorphism Asp299Gly/Thr399Ile.

Toll-like receptor 4 plays a crucial role in the immune-adrenal response to systemic inflammatory response syndrome

Sepsis and septic shock are leading killers in the noncoronary intensive care unit, and they remain worldwide health concerns. The initial host defense against bacterial infections involves Toll-like receptors (TLRs), which detect and respond to microbial ligands. In addition, a coordinated response of the adrenal and immune systems is crucial for survival during severe inflammation. Previously, we demonstrated a link between the innate immune system and the endocrine stress response involving TLR-2. Like TLR-2, TLR-4 is also expressed in human and mouse adrenals. In the present work, by using a low dose of LPS to mimic systemic inflammatory response syndrome, we have revealed marked cellular alterations in adrenocortical tissue and an impaired adrenal corticosterone response in TLR-4-/- mice. Our findings demonstrate that TLR-4 is a key mediator in the crosstalks between the innate immune system and the endocrine stress response. Furthermore, TLR polymorphisms could contribute to the underlying mechanisms of impaired adrenal stress response in patients with bacterial sepsis.

Toll-like receptor (TLR)-9 promotor polymorphisms and atherosclerosis

BACKGROUND

Currently, the primary cause of atherosclerosis remains controversial: while oxidized or enzymatically altered LDL is widely accepted as one cause of the inflamed lesion, microorganisms such as C. pneumoniae or cytomegalovirus (CMV) also have recently been postulated to be involved in the pathogenesis of atherosclerosis. Microbial products activate innate immune cells of the host via Toll-like receptors (TLRs). Common polymorphisms of the TLR-2 and TLR-4 genes have been shown to be associated with an increased risk for restenosis after PTCA, and a lower risk of carotid atherosclerosis, respectively. Microbial DNA has been shown to activate immune cells via the cytosolic TLR-9. Specially, C. pneumonia and CMV as intracellular pathogens may be potent trigger of TLR-9 signaling. Therefore, we investigated whether the two common promotor polymorphisms of the TLR-9 gene are correlated with atherogenesis.

METHODS

The T-1237C and the T-1486C polymorphisms were analyzed by Real Time PCR in 202 (derivation study, age 58.1, SD 10.0) and 182 (validation study, age 59.7, SD 9.6) patients that underwent angioplasty and 188 healthy controls (age 52.5, SD 6.1). Restenosis was defined as >50% luminal diameter reduction at follow-up angiography.

RESULTS

We found the two polymorphism being able to create new potential binding sites for transcription factors, however, no association of the TLR-9 polymorphisms with atherogenesis or restenosis was detectable.

CONCLUSION

Our data indicate that the two TLR-9 promotor polymorphisms are not involved in atherogenesis.

Mutations in Innate Immune System NOD2/CARD 15 and TLR-4 (Thr399Ile) Genes Influence the Risk for Severe Acute Graft-versus-Host Disease in Patients Who Underwent an Allogeneic Transplantation

BACKGROUND

NOD2 and TLR-4 genes belong to the innate immune system that detects invading pathogens through several pattern-recognition receptors. Here we analyzed 403 patients for NOD2 gene mutations and 307 patients for TLR-4 gene mutations (Thr399Ile) with their respective donors and correlated the results with the incidence of acute graft-versus-host disease (aGVHD), severe acute GVHD (saGVHD), the risk for transplant-related mortality (TRM), overall survival (OS) and incidence of infectious complications.

METHODS

We performed a retrospective single-center study. Genotyping of TLR-4 and NOD2 were evaluated by real-time polymerase chain reaction.

RESULTS

Surprisingly, we found a significant reduced incidence of aGVHD, saGVHD, and intestinal GVHD for patients with NOD2 gene mutations on the donor side with 50%, 0% and 2% compared to patients with the wild-type NOD2 gene with 65%, 17%, and 26%, respectively (P<0.02). However, the incidence of saGVHD increased in patients with NOD2 mutations on the patient and donor (P/D) side with 44% versus 17% compared to patients with the wild-type gene (P<0.03). TLR-4 gene mutations at P/D side had an increased risk for saGVHD with 42% versus 15% of patients with wild-type gene (P<0.04). OS, TRM, and incidence of infectious complications were not influenced by the mutated genes. Multivariate analysis confirmed that NOD2 gene mutations on the donor side had a reduced risk for saGVHD (P<0.001), whereas mutations of the NOD2 gene on P/D side had an increased risk for saGVHD (P<0.01) in our analysis.

CONCLUSIONS

These results suggest that NOD2 mutations have influence on the occurrence of acute GVHD after transplantation.

Toll-like receptor (TLR) polymorphisms in African children: Common TLR-4 variants predispose to severe malaria

Genetic host factors play a substantial role in susceptibility to and severity of malaria, which continues to cause at least one million deaths per year. Recently, members of the toll-like receptor (TLR) family have been shown to be involved in recognition of the etiologic organism Plasmodium falciparum: The glycosylphosphatidylinositol anchor induces signaling in host cells via TLR-2 and -4, whereas hemozoin-induced immune activation involves TLR-9. Binding of microbial ligands to the respective TLRs triggers the release of proinflammatory cytokines via the TLR/IL-1 receptor (TIR) domain and may contribute to the host response in malaria, including cytokine induction and fever. In a case-control study among 870 Ghanaian children, we examined the influence of TLR-2, -4, and -9 polymorphisms in susceptibility to severe malaria. TLR-2 variants common in Caucasians and Asians were completely absent. However, we found a rare previously undescribed mutation (Leu658Pro), which impairs signaling via TLR-2. We failed to detect any polymorphisms within the TLR-9 Toll/IL-1 receptor domain. Two frequent TLR-9 promoter polymorphisms did not show a clear association with malaria severity. In contrast, the TLR-4-Asp299Gly variant occurred at a high rate of 17.6% in healthy controls and was even more frequent in severe malaria patients (24.1%, P < 0.05). Likewise, TLR-4-Thr399Ile was seen in 2.4% of healthy children and in 6.2% of patients (P = 0.02). TLR-4-Asp299Gly and TLR-4-Thr399Ile conferred 1.5- and 2.6-fold increased risks of severe malaria, respectively. These findings suggest TLR4-mediated responses to malaria in vivo and TLR-4 polymorphisms to be associated with disease manifestation.

Association study of Toll-like receptor 9 gene polymorphism in Korean patients with systemic lupus erythematosus

Mammalian Toll-like receptors (TLR) play an important role in both adaptive immunity and innate immunity. Genetic variations within TLR genes are known to be associated with a variety of inflammatory and infectious diseases. TLR9 is potentially associated with autoimmune diseases, because it participates in the production of pro-inflammatory cytokines and the maturation of dendritic cells. We investigated the association of four TLR9 gene polymorphisms (-1486 T>C, -1237 C>T, +1174 A>G and +2848 G>A) with the susceptibility to systemic lupus erythematosus (SLE) and related phenotypes in 680 Korean people (350 SLE patients and 330 controls). TLR9 gene polymorphisms were not significantly associated with the susceptibility to SLE and related phenotypes.

A frequent toll-like receptor (TLR)-2 polymorphism is a risk factor for coronary restenosis

Restenosis is a major problem for patients undergoing percutaneous transluminal coronary angioplasty (PTCA). Inflammatory processes and genetic factors have been suggested to be involved in the pathogenesis of both atherosclerosis and restenosis. The recently discovered family of Toll-like receptors (TLRs) consists of molecules that initiate signaling after host-pathogen interactions. Recently it has been shown that the TLRs are involved in the development and progression of atherosclerosis by interfering with lipid metabolisms and by mediating inflammation. TLR-2 is a key innate immunity receptor for sensing both endogenous inflammatory mediators and ligands of several microbial pathogens postulated to be involved in atherosclerosis. A frequent single nucleotide polymorphism (SNP) for the TLR-2 gene, resulting in a non-functional receptor, has been described. By genotyping two independent groups of patients receiving PTCA, followed by stent implantation in one group, we found a significantly enhanced frequency of the TLR-2 Arg753Gln SNP in patients with restenosis as compared to those without restenosis (PTCA: 7.21 versus 2.45%, P = 0.014; PTCA/stent: 6.86 versus 1.53%, P = 0.013). In contrast, a common TLR-4 SNP was similarly distributed among the patient groups investigated. We furthermore compared the frequency of both SNPs in the patients with an age-matched group of individuals without atherosclerosis and found a trend towards a lower frequency of the TLR-4 SNP in the atherosclerotic group (PTCA: 5.58; PTCA/stent: 3.85 versus 7.14%). We conclude that in restenosis a functional TLR-2 is protective and potentially involved in a reaction pattern preventing restenosis. Screening for the TLR-2 Arg753Gln SNP may be of importance for stratifying a patient's risk and for preventive and therapeutic measures.

Single nucleotide polymorphisms of Toll-like receptors and susceptibility to infectious disease

Toll-like receptors (TLRs) play an important part in the innate immune recognition of invading microorganisms, initiating sufficient immune responses. Growing amounts of data suggest that the ability of certain individuals to respond properly to TLR ligands may be impaired by single nucleotide polymorphisms (SNPs) within TLR genes, resulting in an altered susceptibility to, or course of, infectious or inflammatory disease. Most studies have focused on two cosegregating SNPs-Asp299gly and Thr399Ile-within the gene encoding TLR4, the receptor for bacterial lipopolysaccharide. These SNPs are present in approximately 10% of white individuals, and have been found to be positively correlated with several infectious diseases. However, these SNPs seem to protect from atherosclerosis and related diseases, which is reviewed in this article also. Meanwhile, SNPs of genes encoding other TLRs-eg, TLR2, which recognises a wide variety of microbial ligands-have been reported, and preliminary studies indicate an impact on susceptibility to infectious and inflammatory diseases as well. This review summarises and discusses the results obtained, and draws conclusions from these data.

Host cell–pathogen interface: molecular mechanisms and genetics

Host factors determining the host-pathogen interaction are crucial for the reaction pattern leading to the threat of nosocomial infections. A soluble protein with the ability to recognize a variety of microorganisms is LPS binding protein (LBP). The recently identified family of Toll-like receptors (TLRs) represents the major group of cellular signaling receptors for pathogens. The discovery of genetic variations of these proteins caused by single nucleotide polymorphisms (SNPs) has led to first studies aimed at elucidating a potential link between genomic variation of the host and susceptibility to infections. The current state of these analyses is summarized here.