Toll-like receptor (TLR2 and TLR4) polymorphisms and chronic obstructive pulmonary disease

Synonymous mutations in TLR2 and TLR9 genes decrease COPD susceptibility in the Chinese Han population

INTRODUCTION

Previous studies have found associations between polymorphisms in some candidate genes and chronic obstructive pulmonary disease (COPD) risk. However, the association between TLR2 and TLR9 polymorphisms and COPD risk remains uncertain.

METHODS

Four variants (rs352140, rs3804099, rs3804100, and rs5743705) of the TLR2 and TLR9 genes in 540 COPD patients and 507 healthy controls were genotyped using the Agena MassARRAY system. Odds ratio (OR) and 95% confidence interval (CI) were calculated to assess the association of TLR2 and TLR9 polymorphisms with COPD risk by logistic regression analysis.

RESULTS

TLR9-rs352140, TLR2-rs3804100, and TLR2-rs5743705 were related to a lower risk of COPD among Chinese people and the significance still existed after Bonferroni correction. Additionally, rs3804099, rs3804100, and rs352140 were found to be associated with COPD development in different subgroups (males, age ≤ 68 years, smokers, BMI < 24 kg/m2, and acute exacerbation).

CONCLUSIONS

Our findings indicated that TLR9 and TLR2 polymorphisms had protective effects on the development of COPD among Chinese people.

Lactobacillus rhamnosus Restores Antiviral Signaling and Attenuates Cytokines Secretion from Human Bronchial Epithelial Cells Exposed to Cigarette Smoke and Infected with SARS-CoV-2

Individuals with chronic obstructive pulmonary disease (COPD) are more susceptible to exacerbation crisis triggered by secondary lung infections due to the dysfunction of antiviral signaling, principally via suppression of IFN-γ. Although the probiotic is known for controlling pulmonary inflammation in COPD, the influence of the Lactobacillus rhamnosus (Lr) on antiviral signaling in bronchial epithelium exposed to cigarette smoke extract (CSE) and viruses, remains unknown. Thus, the present study investigated the Lr effect on the antiviral signaling and the secretion of inflammatory mediators from bronchial epithelial cells (16HBE cells) exposed to CSE and SARS-CoV-2. The 16HBE cells were cultured, treated with Lr, stimulated with CSE, and infected with SARS-CoV-2. The cellular viability was evaluated using the MTT assay and cytotoxicity measured by lactate dehydrogenase (LDH) activity. The viral load, TLR2, TLR3, TLR4, TLR7, TLR8, MAVS, MyD88, and TRIF were quantified using specific PCR. The pro-inflammatory mediators were measured by a multiplex biometric immunoassay, and angiotensin converting enzyme 2 (ACE2) activity, NF-κB, RIG-I, MAD5, and IRF3 were measured using specific ELISA kits. Lr decreased viral load, ACE2, pro-inflammatory mediators, TLR2, TLR4, NF-κB, TLR3, TLR7, and TLR8 as well as TRIF and MyD88 expression in CSE and SARS-CoV-2 -exposed 16HBE cells. Otherwise, RIG-I, MAD5, IRF3, IFN-γ, and the MAVS expression were restored in 16HBE cells exposed to CSE and SARS-CoV-2 and treated with Lr. Lr induces antiviral signaling associated to IFN-γ secreting viral sensors and attenuates cytokine storm associated to NF-κB in bronchial epithelial cells, supporting its emerging role in prevention of COPD exacerbation.

The Effects and Pathogenesis of PM2.5 and Its Components on Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD), a heterogeneous disease, is the leading cause of death worldwide. In recent years, air pollution, especially particulate matter (PM), has been widely studied as a contributing factor to COPD. As an essential component of PM, PM2.5 is associated with COPD prevalence, morbidity, and acute exacerbations. However, the specific pathogenic mechanisms were still unclear and deserve further research. The diversity and complexity of PM2.5 components make it challenging to get its accurate effects and mechanisms for COPD. It has been determined that the most toxic PM2.5 components are metals, polycyclic aromatic hydrocarbons (PAHs), carbonaceous particles (CPs), and other organic compounds. PM2.5-induced cytokine release and oxidative stress are the main mechanisms reported leading to COPD. Nonnegligibly, the microorganism in PM 2.5 may directly cause mononuclear inflammation or break the microorganism balance contributing to the development and exacerbation of COPD. This review focuses on the pathophysiology and consequences of PM2.5 and its components on COPD.

Association of toll-like receptors polymorphisms with COPD risk in Chinese population

Background: Previous studies have reported that the Toll-like receptors (TLRs) are related with the progress of chronic obstructive pulmonary disease (COPD). We aimed to explore the association of TLRs single nucleotide polymorphisms (SNPs) and COPD risk. Methods: 170 COPD patients and 181 healthy controls were enrolled in this case-control study. MassARRAY platform was used for genotyping seven tagging SNPs (TLR2: rs3804100, rs4696480, rs3804099; TLR3: rs3775290, rs3775291, rs5743305; TLR9: rs352140) of TLRs. The correlations between the SNPs and COPD risk were determined using logistic regression. Results: We found that the rs3775291 of TLR3 significant decreased the risk of COPD (TT versus CC: non-adjusted OR = 0.329, 95% CI = 0.123-0.879, p = 0.027). In the genetic models analysis, the rs3775291 was associated with a decreased effect of COPD based on the recessive model (TT versus CC/CT: non-adjusted OR = 0.377, 95% CI = 0.144-0.988 p = 0.047). The rs4696480 of TLR2 gene was associated with a decreased risk of COPD after adjustment by age and gender (TA versus AA: adjusted OR = 0.606, 95% CI = 0.376-0.975, p = 0.039). Conclusion: Our study showed that genetic variants in TLRs were associated with risk of COPD. The rs3775291 and rs4696480 may act as a potential biomarker for predicting the risk of COPD in Chinese population.

The role of HMGB1/RAGE/TLR4 signaling pathways in cigarette smoke-induced inflammation in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a common chronic respiratory disease with irreversible and continuous progression. It has become the fifth most burdensome disease and the third most deadly disease globally. Therefore, the prevention and treatment of COPD are urgent, and it is also important to clarify the pathogenesis of it. Smoking is the main and most common risk factor for COPD. Cigarette smoke (CS) can cause lung inflammation and other pathological mechanisms in the airways and lung tissue. Airway inflammation is one of the important mechanisms leading to the pathogenesis of COPD. Recent studies have shown that high mobility group box 1 (HMGB1) is involved in the occurrence and development of respiratory diseases, including COPD. HMGB1 is a typical damage-associated molecular pattern (DAMP) protein, which mainly exerts its activity by binding to the receptor for advanced glycation end products (RAGE) and toll-like receptor 4 (TLR4) and further participate in the process of airway inflammation. Studies have shown that the abnormal expression of HMGB1, RAGE, and TLR4 are related to inflammation in COPD. Herein, we discuss the roles of HMGB1, RAGE, and TLR4 in CS/cigarette smoke extract-induced inflammation in COPD, providing a new target for the diagnosis, treatment and prevention of COPD.

Single Nucleotide Polymorphisms of Toll-like Receptor 4 in Hepatocellular Carcinoma-A Single-Center Study

Hepatocellular carcinoma (HCC) is the most common primary liver tumor leading to significant morbidity and mortality; its exact genetic background is largely unrecognized. Toll-like receptor-4 (TLR4) reacts with lipopolysaccharides, molecules found in the outer membrane of Gram-negative bacteria. In damaged liver, TLR4 expression is upregulated, leading to hepatic inflammation and injury. We tried to investigate the role of the two most common single-nucleotide polymorphisms (SNPs) of TLR4 in HCC-genesis. Aged > 18 years old, cirrhotic patients were included in this study. Exclusion criteria were non-HCC tumors and HIV co-infection. TLR4 SNPs association with HCC occurrence was the primary endpoint, and associations with all-cause and liver-related mortality, as well as time durations between diagnosis of cirrhosis and HCC development or death and diagnosis of HCC and death were secondary endpoints. A total of 52 out of 260 included patients had or developed HCC. TLR4 SNPs showed no correlation with primary or secondary endpoints, except for the shorter duration between HCC development and death in patients with TLR4 mutations. Overall, TLR4 SNPs showed no correlation with carcinogenesis or deaths in patients with liver cirrhosis; patients with TLR4 SNPs that developed HCC had lower survival rates, a finding that should be further evaluated.

Transmembrane protease serine 2 (TMPRSS2) rs75603675, comorbidity, and sex are the primary predictors of COVID-19 severity

The TMPRSS2 rs75603675 genotype (OR = 0.586), dyslipidemia (OR = 2.289), sex (OR = 0.586), and the Charlson Comorbidity Index (OR = 1.126) were identified as the main predictors of COVID-19 severity in 817 patients who attended Hospital Universitario de La Princesa during March and April 2020.

By the end of December 2021, coronavirus disease 2019 (COVID-19) produced more than 271 million cases and 5.3 million deaths. Although vaccination is an effective strategy for pandemic control, it is not yet equally available in all countries. Therefore, identification of prognostic biomarkers remains crucial to manage COVID-19 patients. The aim of this study was to evaluate predictors of COVID-19 severity previously proposed. Clinical and demographic characteristics and 120 single-nucleotide polymorphisms were analyzed from 817 patients with COVID-19, who attended the emergency department of the Hospital Universitario de La Princesa during March and April 2020. The main outcome was a modified version of the 7-point World Health Organization (WHO) COVID-19 severity scale (WHOCS); both in the moment of the first hospital examination (WHOCS-1) and of the severest WHOCS score (WHOCS-2). The TMPRSS2 rs75603675 genotype (OR = 0.586), dyslipidemia (OR = 2.289), sex (OR = 0.586), and the Charlson Comorbidity Index (OR = 1.126) were identified as the main predictors of disease severity. Consequently, these variables might influence COVID-19 severity and could be used as predictors of disease development.

Role of Toll-Like Receptor 2 in Regulation of T-Helper Immune Response in Chronic Obstructive Pulmonary Disease

Objective

According to modern views, the differences in the clinical course of chronic obstructive pulmonary disease (COPD) are associated with certain types of T-helper (Th) immune response. Recent data have shown that toll-like receptor 2 (TLR2) is involved in the development of Th immune response. However, TLR2-mediated regulation of Th subpopulation balance in COPD needs to be elucidated. The aim of our work is to determine the mechanisms of TLR2-mediated regulation of Th immune response in COPD of varying severity.

Methods

The study included 323 smokers/ex-smokers with stable COPD (GOLD I, GOLD II, and GOLD III) and 97 healthy nonsmokers (control group). Serum levels of Th1 (TNF-α and IFN-γ), Th2 (IL-4), Th17 (IL-6 and IL-17A), Treg (IL-10) cytokines, and the percentage of peripheral blood Th cells expressing TLR2 (CD4⁺CD282⁺) were assessed by flow cytometry. Serum concentrations of IL-21 (Th17) and TGF-β1 (Treg) were measured using the ELISA method. The predominant Th cytokine profile in serum was determined by calculating the ratios between levels of Th1 and Th17 cytokines. Spearman's correlation test was performed.

Results

Patients with COPD GOLD II and III with Th1 and Th17 cytokine profiles exhibited an increase in the percentage of CD4⁺CD282⁺ cells compared to the control group. In COPD GOLD I–III, positive correlations between CD4⁺CD282⁺ cell frequency and Th17 cytokine levels (IL-6, IL-17A, and IL-21) were found. In COPD GOLD I, IL-10 concentration was negatively correlated with the percentages of studied cells; in COPD GOLD II, a positive correlation between these parameters was noted.

Conclusions

Enhanced TLR2 expression on CD4⁺ cells shifts cytokine profile toward Th17 phenotype that plays a crucial role in COPD progression. The level of TLR2 expression on peripheral blood CD4⁺ cells may be considered as a biomarker for diagnosing and predicting the progression of COPD.

Increased HSP70 and TLR2 Gene Expression and Association of HSP70 rs6457452 Single Nucleotide Polymorphism with the Risk of Chronic Obstructive Pulmonary Disease in the Croatian Population

Heat shock protein 70 (Hsp70) engages Toll-like receptors (TLR) 2 and 4 when found in the extracellular compartment and contributes to inflammation in chronic obstructive pulmonary disease (COPD). Since there is growing evidence for the genetic risk factors for COPD, the gene expression of HSP70, TLR2 and TLR4 was determined, as well as the association between HSP70, TLR2 and TLR4 single nucleotide polymorphisms, (SNPs) and COPD. The gene expression was assessed in peripheral blood cells of 137 COPD patients and 95 controls by a quantitative polymerase chain reaction (qPCR), while a total of nine SNPs were genotyped by TaqMan allelic discrimination real-time PCR. HSP70 and TLR2 gene expression was increased in COPD patients compared to the controls, regardless of the disease severity and smoking status of participants. The rs6457452 SNP of HSP70 was associated with COPD, indicating the protective role of the T allele (OR = 0.46, 95% CI = 0.24–0.89, p = 0.022). Furthermore, COPD C/T heterozygotes showed a decreased HSP70 mRNA level compared to COPD C/C homozygotes. In conclusion, HSP70 and TLR2 may have a role in the pathogenesis of COPD, and the HSP70 rs6457452 variant might influence the genetic susceptibility to COPD in the Croatian population.

Association of TLR4 gene polymorphisms with sepsis after a burn injury: findings of the functional role of rs2737190 SNP

Sepsis is a life-threatening organ dysfunction condition caused by a dysregulated response to an infection that is common among patients with moderate to severe burn injury. Previously, genomic variants in Toll-like receptor 4 (TLR4), a key innate immunity receptor, have been associated with sepsis and infection susceptibility. In this study, the association of six TLR4 SNPs with sepsis after burn injury was tested in the Mexican mestizo population. We found that the rs2737190 polymorphism is associated with sepsis after burn trauma. Interestingly, the G allele and GG genotype were associated with a lower risk of developing sepsis. Since the rs2737190 SNP is in the promoter region of the TLR4 gene, we analyzed the possibility that this polymorphism regulates the TLR4 pathway. We cultured peripheral blood mononuclear cells from different genotype carriers and found, after stimulation with LPS, that carriers of the GG genotype showed a higher expression of TLR4, IL6, and TNFα than AA genotype carriers. The results suggest that the GG genotype produces an increase in the TLR4 expression, and therefore an improvement in the immune response. We conclude that the rs2737190 polymorphism may become a useful marker for genetic studies of sepsis in patients after a burn injury.

miRNA-486-5p Promotes COPD Progression by Targeting HAT1 to Regulate the TLR4-Triggered Inflammatory Response of Alveolar Macrophages

Purpose

The aim of this study was to investigate the role of miRNA-486-5p in chronic obstructive pulmonary disease (COPD) progression and the underlying molecular mechanisms.

Materials and Methods

Aberrant miRNA expression profiles between smokers and nonsmokers, and those between COPD patients and normal subjects were analyzed using microarray datasets and reverse-transcriptase quantitative polymerase chain reaction (qPCR). Enzyme-linked immunosorbent assay was used to determine the levels of inflammatory cytokines in cell supernatants. Expression levels of inflammatory cytokines, HAT1, TLR4, and miR-486-5p, were determined using qPCR or Western blotting. Luciferase reporter assays and fluorescence in situ hybridization were used to confirm the regulatory interaction between miR-486-6p and HAT1.

Results

miR-486-5p was significantly upregulated in the COPD and smoker groups compared to the control group, as demonstrated using bioinformatics analysis and validated using qPCR assay of alveolar macrophages and peripheral monocytes. Moreover, miR-486-5p expression was significantly correlated with the expression of IL-6, IL-8, TNF-α, and IFN-γ. Luciferase reporter assays confirmed that miR-486-5p directly targeted HAT1, and cellular localization showed that miR-486-5p and HAT1 were highly expressed in the cytoplasm. miR-486-5p overexpression led to a significant upregulation of TLR4 and a significant downregulation of HAT1. Inversely, miR-486-5p inhibition led to a significant downregulation of TLR4 and a significant upregulation of HAT1. HAT1 knockdown using siRNA significantly upregulated the expression of TLR4, IL-6, IL-8, TNF-α, and IFN-γ.

Conclusion

miR-486-5p was differentially expressed in the alveolar macrophages of COPD patients. miR-486-5p overexpression may enhance the TLR4-triggered inflammatory response in COPD patients by targeting HAT1.

Toll-like receptor 10 rs4129009 gene polymorphism is associated with post-bronchiolitis lung function in adolescence

AIM

The aim was to evaluate the association of polymorphisms in the Toll-like receptor (TLR) 2 subfamily encoding genes with lung function by spirometry at 10-13 years of age in children who had been hospitalised for bronchiolitis at <6 months of age.

METHODS

In a prospective cohort of 166 former bronchiolitis patients, 138 returned a structured questionnaire and 89 attended a clinical follow-up visit including spirometry before and after bronchodilation at 10-13 years of age. Data on polymorphisms of the TLR1, TLR2, TLR6 and TLR10 genes were available from 81-82 children.

RESULTS

In the TLR10 rs4129009, the wild (AA) genotype was associated with lower FEV1/FVC before (92.4 vs 97.4, P = .002) and after (95.5 vs 98.6, P = .011) bronchodilator administration, compared to those with the variant genotype. When the TLR10 rs4129009 and TLR2 rs5743708 genotypes, and the TLR10 rs4129009 and TLR1 rs5743618 genotypes, respectively, were analysed as combined, both baseline and post-bronchodilator FEV1/FVC were lowest in the subjects with the wild (AA) genotype of the TLR10 rs4129009.

CONCLUSION

In this post-bronchiolitis follow-up, lung function in children with the variant TLR10 rs4129009 genotype with potentially altered TLR10 function was superior to lung function in those with the wild genotype.

The Association of rs1898830 in Toll-Like Receptor 2 with Lipids and Blood Pressure

BACKGROUND AND OBJECTIVE

Toll-like receptors (TLRs) are important components of the innate immune system, involved in establishing immunity to infections. Apart from being implicated in immunity, numerous studies have reported that many TLRs, including TLR2, are involved in the pathogenesis of cardiovascular diseases and their risk factors. Since rs1898830 is associated with TLR2-mediated cellular activation, we aimed to study its association with CVD risk factors, such as lipid levels and hypertension.

METHODS

A cross-sectional study was conducted on 460 individuals free from chronic diseases. Clinical and biological data were collected and DNA was extracted and genotyped using Kompetitive allele specific PCR (KASP™). Multiple logistic regression models, adjusted for six covariates, were used. A power calculation analysis was also performed.

RESULTS

We found that rs1898830 in TLR2 was positively associated with hypertension (OR = 2.18, p = 0.03) and negatively associated with high-density lipoprotein cholesterol (OR = 0.66, p = 0.05). In contrast, no relation was found with total cholesterol and low-density lipoprotein cholesterol.

CONCLUSION

The present results provide additional evidence supporting the implication of TLR2 in CVD risk factors.

The Role of Toll-Like Receptors 2 and 4 in the Pathogenesis of Chronic Obstructive Pulmonary Disease

Currently, chronic obstructive pulmonary disease (COPD) is one of the leading causes of morbidity and mortality worldwide. The determination of immune mechanisms of inflammation in the disease presents an important challenge for fundamental medical research. According to modern views, Toll-like receptors (TLRs), among which TLR2 and TLR4 play a key role, are one of the essential components of inflammatory process in COPD. This review focuses on following aspects: the role of TLR2 and TLR4 in the initiation of inflammatory process in COPD; the mechanisms of influence of various exogenous factors (cigarette smoke, suspended particulate matter, and bacteria) on the expression of TLR2 and TLR4; the contribution of these TLRs to the T-helper (Th) immune response development in COPD, in particular to the Th17 immune response, which contributes to the progression of the disease and therapeutic implications of TLR2 and TLR4 in COPD.

Innate Immunity and Cell Surface Receptors in the Pathogenesis of COPD: Insights from Mouse Smoking Models

Chronic obstructive pulmonary disease (COPD) is mainly associated with smoking habit. Inflammation is the major initiating process whereby neutrophils and monocytes are attracted into the lung microenvironment by external stimuli present in tobacco leaves and in cigarette smoke, which promote chemotaxis, adhesion, phagocytosis, release of superoxide anions and enzyme granule contents. A minority of smokers develops COPD and different molecular factors, which contribute to the onset of the disease, have been put forward. After many years of research, the pathogenesis of COPD is still an object of debate. In vivo models of cigarette smoke-induced COPD may help to unravel cellular and molecular mechanisms underlying the pathogenesis of COPD. The mouse represents the most favored animal choice with regard to the study of immune mechanisms due to its genetic and physiological similarities to humans, the availability of a large variability of inbred strains, the presence in the species of several genetic disorders analogous to those in man, and finally on the possibility to create models “made-to-measure” by genetic manipulation. The review outlines the different response of mouse strains to cigarette smoke used in COPD studies while retaining a strong focus on their relatability to human patients. These studies reveal the importance of innate immunity and cell surface receptors in the pathogenesis of pulmonary injury induced by cigarette smoking. They further advance the way in which we use wild type or genetically manipulated strains to improve our overall understanding of a multifaceted disease such as COPD. The structural and functional features, which have been found in the different strains of mice after chronic exposure to cigarette smoke, can be used in preclinical studies to develop effective new therapeutic agents for the different phenotypes in human COPD.

Functional variations of the TLR4 gene in association with chronic obstructive pulmonary disease and pulmonary tuberculosis

Objective

Chronic obstructive pulmonary disease (COPD) and pulmonary tuberculosis (PTB) share a number of common risk factors, including innate immunity-related genetic factors. In the present study, we compared the role of genetic variations of the TLR4 gene in susceptibility to COPD and PTB and illuminated the underlying molecular mechanism of functional single-nucleotide polymorphisms (SNPs).

Methods

A population-based case control study was performed in a Chinese Han population and included 152 COPD cases, 1601 PTB cases and 1727 controls. Five SNPs in the TLR4 gene (rs10759932, rs2737190, rs7873784, rs11536889, and rs10983755) were genotyped using TaqMan allelic discrimination technology. We estimated the effects of SNPs using the odds ratio (OR) together with 95% confidence interval (CI). Dual-luciferase reporter vectors expressing different genotypes of SNPs were constructed and transfected into the human HEK 293 T cell line to explore their effects on potential transcription activity.

Results

After Bonferroni correction, the genetic polymorphisms of all five SNPs remained significantly associated with COPD, while rs10759932 and rs2737190 were also associated with PTB. Compared with rs10759932-TT, individuals carrying TC (OR: 0.42, 95% CI: 0.28–0.64) or CC (OR: 0.24, 95% CI: 0.09–0.63) had a significantly reduced risk of COPD. However, individuals carrying TC (OR: 1.28, 95% CI: 1.11–1.49) or CC (OR: 1.26, 95% CI: 0.98–1.62) had an increased risk of PTB. The OR (95% CI) for allele rs10759932-C was 0.45 (0.32–0.62) for COPD and 1.18 (1.07–1.32) for PTB. For rs2737190, heterozygous AG was related to a decreased risk of COPD (OR: 0.32, 95% CI: 0.21–0.49) and an increased risk of PTB (OR: 1.30, 95% CI: 1.11–1.52). The dual-luciferase reporter assay showed decreased transcription activity caused by rs10759932-C and rs2737190-G.

Conclusion

Genetic polymorphisms of rs10759932 and rs2737190 in TLR4 are significantly related to both COPD and PTB but with inverse effects. The altered transcription activity caused by mutations in these two loci may partly explain the observed relationship.

Association of TLR4 and TLR9 gene polymorphisms and haplotypes with cervicitis susceptibility

BACKGROUND

Cervicitis is one of the major health problems amongst women caused by infection of various pathogens including Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), Trichomonas vaginalis (TV) as well as human papillomavirus (HPV), and persistent cervical inflammation is one of the etiologic agents of cervical cancer. Toll-like receptors (TLRs) play an important role in the recognition and subsequent elimination of these pathogens. Variations in the Toll-like receptor genes influence susceptibility to pathogens as well as disease progression independently.

METHODS

Ten single nucleotide polymorphisms, five each of TLR4 and TLR9 genes were analyzed among 130 cervicitis patients and 150 controls either using polymerase chain reaction-restriction fragment length polymorphism or allele specific-PCR.

RESULTS

T. vaginalis infection was found at the highest frequency (30.7%) as compared to C. trachomatis (1.5%), N. gonorrhoeae (2.3%) and HPV (4.6%) infections in cervicitis patients. TLR4 rs11536889 CC (age-adjusted OR, 2.469 [95% CI, 1.499 to 4.065]; p < 0.001) and TLR9 rs187084 TC (age-adjusted OR, 2.165 [95% CI, 1.267-3.699]; p = 0.005) genotypes showed the higher distribution in cervicitis patients compared to controls. In addition, TLR4 rs11536889 C allele was shown to increase the risk of cervicitis (age-adjusted OR, 1.632 [95% CI, 1.132 to 2.352]; p = 0.009) compared to controls. The TLR4 haplotype GCA (OR, 0.6 [95% CI, 0.38-0.95]; p = 0.0272) and TLR9 haplotype GTA (OR, 1.99 [95% CI, 1.14-3.48]; p = 0.014) were found to be associated with decreased and increased risk of cervicitis respectively.

CONCLUSIONS

TLR4 and TLR9 polymorphisms, as well as haplotypes were shown to modulate the cervicitis risk.

The polymorphism rs4696480 in the TLR2 gene is associated with psoriasis patients in the Turkish population

BACKGROUND

Toll-like receptors (TLRs) have an important role in the host defense. Recent studies demonstrated that TLR polymorphisms might have a role in the pathogenesis of psoriasis vulgaris. The aim of this study was to indicate whether TLR2 rs11938228 and rs4696480 were associated with susceptibility to psoriasis in the Turkish population.

METHODS

This case-control study included 140 psoriasis patients and 250 controls. Genotyping of 2 rs11938228 and rs4696480 SNPs of TLR2 were determined using LightSNiP Kit (Roche Diagnostic, GmBH, Mannheim, Germany).

RESULTS

Our results demonstrated that the TLR2-rs4696480 AA genotype seemed to have a higher risk for psoriasis [crude 95% CI: 1.495-4.514, and p < 0.001, adjusted 95% CI: 1.349-4.292, and p = 0.003] while as TLR2-rs11938228 polymorphism has not shown any significant association with the risk of psoriasis [p > 0.005]. There was no statistically significant difference between the mean age, gender, onset age, and PASI level and genotypes for rs11938228 and rs4696480 polymorphisms (p > 0.05).

CONCLUSIONS

The SNP rs4696480 of TLR2 may have significant effects on the heritability of psoriasis in the Turkish population.

The Interplay Between Immune Response and Bacterial Infection in COPD: Focus Upon Non-typeable Haemophilus influenzae

Chronic obstructive pulmonary disease (COPD) is a debilitating respiratory disease and one of the leading causes of morbidity and mortality worldwide. It is characterized by persistent respiratory symptoms and airflow limitation due to abnormalities in the lower airway following consistent exposure to noxious particles or gases. Acute exacerbations of COPD (AECOPD) are characterized by increased cough, purulent sputum production, and dyspnea. The AECOPD is mostly associated with infection caused by common cold viruses or bacteria, or co-infections. Chronic and persistent infection by non-typeable Haemophilus influenzae (NTHi), a Gram-negative coccobacillus, contributes to almost half of the infective exacerbations caused by bacteria. This is supported by reports that NTHi is commonly isolated in the sputum from COPD patients during exacerbations. Persistent colonization of NTHi in the lower airway requires a plethora of phenotypic adaptation and virulent mechanisms that are developed over time to cope with changing environmental pressures in the airway such as host immuno-inflammatory response. Chronic inhalation of noxious irritants in COPD causes a changed balance in the lung microbiome, abnormal inflammatory response, and an impaired airway immune system. These conditions significantly provide an opportunistic platform for NTHi colonization and infection resulting in a "vicious circle." Episodes of large inflammation as the consequences of multiple interactions between airway immune cells and NTHi, accumulatively contribute to COPD exacerbations and may result in worsening of the clinical status. In this review, we discuss in detail the interplay and crosstalk between airway immune residents and NTHi, and their effect in AECOPD for better understanding of NTHi pathogenesis in COPD patients.

Toll-like receptor variants and cervical Atopobium vaginae infection in women with pelvic inflammatory disease

PROBLEM

Toll-like (TLR) receptor genetic variants have been implicated in bacterial vaginosis (BV). We determined whether TLR variants are associated with fastidious BV-associated microbes that are linked with infertility following pelvic inflammatory disease (PID).

METHOD OF STUDY

Sneathia spp., Atopobium vaginae, BVAB1, and Ureaplasma urealyticum were measured in 250 women from the PID Evaluation and Clinical Health (PEACH) study. Relative risk (RR) and 95% confidence intervals (CI) were calculated adjusting for chlamydia and gonorrhea. Principal component analysis was used to adjust for population stratification. A false discovery rate q-value of 0.05 was significant.

RESULTS

TLR2-1733C>A (P = .003) and TLR2-616A>G (P = .004) were associated with cervical A. vaginae. TLR2-1733C>A and TLR6-438C>T were associated with A. vaginae detection in the endometrium, but this was not significant after adjustment for multiple comparisons (FDR q-value = 0.06).

CONCLUSION

Host gene variants in TLR2 signaling pathways were modestly associated with cervical A. vaginae in women with clinical PID.

Toll-like receptor 2 and 4 have opposing roles in the pathogenesis of cigarette smoke-induced chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is the third leading cause of morbidity and death and imposes major socioeconomic burdens globally. It is a progressive and disabling condition that severely impairs breathing and lung function. There is a lack of effective treatments for COPD, which is a direct consequence of the poor understanding of the underlying mechanisms involved in driving the pathogenesis of the disease. Toll-like receptor (TLR)2 and TLR4 are implicated in chronic respiratory diseases, including COPD, asthma and pulmonary fibrosis. However, their roles in the pathogenesis of COPD are controversial and conflicting evidence exists. In the current study, we investigated the role of TLR2 and TLR4 using a model of cigarette smoke (CS)-induced experimental COPD that recapitulates the hallmark features of human disease. TLR2, TLR4, and associated coreceptor mRNA expression was increased in the airways in both experimental and human COPD. Compared with wild-type (WT) mice, CS-induced pulmonary inflammation was unaltered in TLR2-deficient ( Tlr2-/-) and TLR4-deficient ( Tlr4-/-) mice. CS-induced airway fibrosis, characterized by increased collagen deposition around small airways, was not altered in Tlr2-/- mice but was attenuated in Tlr4-/- mice compared with CS-exposed WT controls. However, Tlr2-/- mice had increased CS-induced emphysema-like alveolar enlargement, apoptosis, and impaired lung function, while these features were reduced in Tlr4-/- mice compared with CS-exposed WT controls. Taken together, these data highlight the complex roles of TLRs in the pathogenesis of COPD and suggest that activation of TLR2 and/or inhibition of TLR4 may be novel therapeutic strategies for the treatment of COPD.

Modeling DNA damage-induced pneumopathy in mice: insight from danger signaling cascades

Radiation-induced pneumonitis and fibrosis represent severe and dose-limiting side effects in the radiotherapy of thorax-associated neoplasms leading to decreased quality of life or - as a consequence of treatment with suboptimal radiation doses - to fatal outcomes by local recurrence or metastatic disease. It is assumed that the initial radiation-induced damage to the resident cells triggers a multifaceted damage-signalling cascade in irradiated normal tissues including a multifactorial secretory program. The resulting pro-inflammatory and pro-angiogenic microenvironment triggers a cascade of events that can lead within weeks to a pronounced lung inflammation (pneumonitis) or after months to excessive deposition of extracellular matrix molecules and tissue scarring (pulmonary fibrosis).The use of preclinical in vivo models of DNA damage-induced pneumopathy in genetically modified mice has helped to substantially advance our understanding of molecular mechanisms and signalling molecules that participate in the pathogenesis of radiation-induced adverse late effects in the lung. Herein, murine models of whole thorax irradiation or hemithorax irradiation nicely reproduce the pathogenesis of the human disease with respect to the time course and the clinical symptoms. Alternatively, treatment with the radiomimetic DNA damaging chemotherapeutic drug Bleomycin (BLM) has frequently been used as a surrogate model of radiation-induced lung disease. The advantage of the BLM model is that the symptoms of pneumonitis and fibrosis develop within 1 month.Here we summarize and discuss published data about the role of danger signalling in the response of the lung tissue to DNA damage and its cross-talk with the innate and adaptive immune systems obtained in preclinical studies using immune-deficient inbred mouse strains and genetically modified mice. Interestingly we observed differences in the role of molecules involved in damage sensing (TOLL-like receptors), damage signalling (MyD88) and immune regulation (cytokines, CD73, lymphocytes) for the pathogenesis and progression of DNA damage-induced pneumopathy between the models of pneumopathy induced by whole thorax irradiation or treatment with the radiomimetic drug BLM. These findings underline the importance to pursue studies in the radiation model(s) if we are to unravel the mechanisms driving radiation-induced adverse late effects.A better understanding of the cross-talk of danger perception and signalling with immune activation and repair mechanisms may allow a modulation of these processes to prevent or treat radiation-induced adverse effects. Vice-versa an improved knowledge of the normal tissue response to injury is also particularly important in view of the increasing interest in combining radiotherapy with immune checkpoint blockade or immunotherapies to avoid exacerbation of radiation-induced normal tissue toxicity.

Association between TLR2/TLR4 gene polymorphisms and COPD phenotype in a Greek cohort

BACKGROUND

Considering that the innate immune system plays a pivotal role in the pathogenesis of chronic obstructive pulmonary disease (COPD), we hypothesized that functional single-nucleotide polymorphisms (SNPs) of innate immune genes affect the disease phenotype and prognosis.

AIM

To elucidate the contribution of common functional TLR2 and TLR4 SNPs and genotypic deficiency of the mannose-binding lectin (MBL) protein, both as single parameters and in combination, in Greek COPD patients.

RESULTS

In a cohort of 114 Greek COPD patients, we confirmed that the presence of TLR4-D299G or TLR4-T399I SNPs was significantly associated with an earlier COPD stage (p = 0.003 and p = 0.009, respectively). In comparison, the absence of any analyzed polymorphism, including those of TLR2-R753Q and genotypic MBL deficiency, was significantly associated with a more severe disease phenotype, characterized by more frequent exacerbations (p = 0.045).

CONCLUSION

Our findings support the notion that the presence of innate immune SNPs, such as functional polymorphisms of TLRs along with MBL deficiency, might exert a protective effect on the COPD phenotype, similar with other immune-mediated disorders.

Toll-like receptor cascade and gene polymorphism in host-pathogen interaction in Lyme disease

Lyme disease (LD) risk occurs in North America and Europe where the tick vectors of the causal agent Borrelia burgdorferi sensu lato are found. It is associated with local and systemic manifestations, and has persistent posttreatment health complications in some individuals. The innate immune system likely plays a critical role in both host defense against B. burgdorferi and disease severity. Recognition of B. burgdorferi, activation of the innate immune system, production of proinflammatory cytokines, and modulation of the host adaptive responses are all initiated by Toll-like receptors (TLRs). A number of Borrelia outer-surface proteins (eg, OspA and OspB) are recognized by TLRs. Specifically, TLR1 and TLR2 were identified as the receptors most relevant to LD. Several functional single-nucleotide polymorphisms have been identified in TLR genes, and are associated with varying cytokines types and synthesis levels, altered pathogen recognition, and disruption of the downstream signaling cascade. These single-nucleotide polymorphism-related functional alterations are postulated to be linked to disease development and posttreatment persistent illness. Elucidating the role of TLRs in LD may facilitate a better understanding of disease pathogenesis and can provide an insight into novel therapeutic targets during active disease or postinfection and posttreatment stages.

Expression Profiling of LPS Responsive miRNA in Primary Human Macrophages

microRNAs (miRNAs) have emerged as important regulators of the innate and adaptive immune response. The purpose of the present study was to interrogate miRNA profiles of primary human macrophages challenged with bacterial lipopolysaccharide (LPS) with focus on expression kinetics. We employed Nanostring platform to precisely characterize the changes in miRNA expression following different doses and durations of LPS exposure. Differentially expressed miRNAs were identified in response to LPS challenge with convergent and divergent expression profiles. Pathway analysis of LPS-responsive miRNAs revealed regulation of biological processes linked to key cell signaling (including PIK3-Akt, MAP kinase, ErbB) and pathogen response pathways. Our data provide a comprehensive miRNA profiling of human primary macrophages treated with LPS. These results show that bacterial Toll like receptor (TLR) ligands can temporally modulate macrophage miRNA expression.

Cigarette smoke-induced necroptosis and DAMP release trigger neutrophilic airway inflammation in mice

Recent data indicate a role for airway epithelial necroptosis, a regulated form of necrosis, and the associated release of damage-associated molecular patterns (DAMPs) in the development of chronic obstructive pulmonary disease (COPD). DAMPs can activate pattern recognition receptors (PRRs), triggering innate immune responses. We hypothesized that cigarette smoke (CS)-induced epithelial necroptosis and DAMP release initiate airway inflammation in COPD. Human bronchial epithelial BEAS-2B cells were exposed to cigarette smoke extract (CSE), and necrotic cell death (membrane integrity by propidium iodide staining) and DAMP release (i.e., double-stranded DNA, high-mobility group box 1, heat shock protein 70, mitochondrial DNA, ATP) were analyzed. Subsequently, BEAS-2B cells were exposed to DAMP-containing supernatant of CS-induced necrotic cells, and the release of proinflammatory mediators [C-X-C motif ligand 8 (CXCL-8), IL-6] was evaluated. Furthermore, mice were exposed to CS in the presence and absence of the necroptosis inhibitor necrostatin-1, and levels of DAMPs and inflammatory cell numbers were determined in bronchoalveolar lavage fluid. CSE induced a significant increase in the percentage of necrotic cells and DAMP release in BEAS-2B cells. Stimulation of BEAS-2B cells with supernatant of CS-induced necrotic cells induced a significant increase in the release of CXCL8 and IL-6, in a myeloid differentiation primary response gene 88-dependent fashion. In mice, exposure of CS increased the levels of DAMPs and numbers of neutrophils in bronchoalveolar lavage fluid, which was statistically reduced upon treatment with necrostatin-1. Together, we showed that CS exposure induces necrosis of bronchial epithelial cells and subsequent DAMP release in vitro, inducing the production of proinflammatory cytokines. In vivo, CS exposure induces neutrophilic airway inflammation that is sensitive to necroptosis inhibition.

Molecular Regulation of Toll-like Receptors in Asthma and COPD

Asthma and chronic obstructive pulmonary disease (COPD) have both been historically associated with significant morbidity and financial burden. These diseases can be induced by several exogenous factors, such as pathogen-associated molecular patterns (PAMPs) (e.g., allergens and microbes). Endogenous factors, including reactive oxygen species, and damage-associated molecular patterns (DAMPs) recognized by toll-like receptors (TLRs), can also result in airway inflammation. Asthma is characterized by the dominant presence of eosinophils, mast cells, and clusters of differentiation (CD)4⁺ T cells in the airways, while COPD typically results in the excessive formation of neutrophils, macrophages, and CD8⁺ T cells in the airways. In both asthma and COPD, in the respiratory tract, TLRs are the primary proteins of interest associated with the innate and adaptive immune responses; hence, multiple treatment options targeting TLRs are being explored in an effort to reduce the severity of the symptoms of these disorders. TLR-mediated pathways for both COPD and asthma have their similarities and differences with regards to cell types and the pro-inflammatory cytotoxins present in the airway. Because of the complex TLR cascade, a variety of treatments have been used to minimize airway hypersensitivity and promote bronchodilation. Although unsuccessful at completely alleviating COPD and severe asthmatic symptoms, new studies are focused on possible targets within the TLR cascade to ameliorate airway inflammation.

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.

Polymorphisms in Toll-like receptors 2 and 4 genes and their expression in chronic suppurative otitis media

OBJECTIVE

Toll-like receptors (TLRs) have a prominent role in inducing innate immune response. It has been suggested that regulation of TLRs is involved in the pathogenesis of chronic otitis media. TLR 2 and TLR 4 polymorphisms were connected with susceptibility to acute otitis and chronic otitis with effusion. The objective of this study was to establish expression of TLR 2 and 4 on middle ear mucosa in different types of chronic suppurative otitis media (CSOM), and the influence of gene polymorphisms TLR 2 Arg753Gln and TLR 4 Thr399Ile and Asp299Gly to susceptibility to CSOM.

MATERIAL AND METHODS

Middle ear mucosa and full blood samples were obtained from 85 patients with chronic suppurative otitis media with and without cholesteatoma. Control group for mucosal TLR expression consisted of 71 samples of middle ear mucosa taken from patients with otosclerosis, and control group for DNA polymorphism consisted of 100 full blood samples in healthy subjects. DNA polymorphism detection was done with restriction fragment length polymorphism in RT PCR. Expression of TLR 2 and 4 was determined with immunohistochemical staining.

RESULTS

TLR 2 and TLR 4 expression on the middle ear mucosa was not influenced by age of the patients with chronic otitis media. Incidence of TLR 2 Arg753Gln polymorphism was significantly higher in patients with chronic otitis media, compared to control group. Significant association between TLR 2 Arg753Gln polymorphism and different types of mucosal changes in patients with chronic otitis media was established. TLR 2 and 4 expression on experimental group mucosa was significantly different compared to control group, where there was no expression (p=0.000). Strong dependence of TLR 2 and TLR 4 expression on middle ear mucosa with different mucosal changes and immunohistochemical activity after staining was detected.

CONCLUSION

Certain polymorphisms in TLR genes could be indicative for susceptibility to chronic otitis media. Expression of TLR 2 and 4 on middle ear mucosa was more dependable on different types of mucosal changes and type of CSOM than on bacteria found in the specimens. This can indicate that the type of mucosal changes are closely correlated with TLRs activity in middle ear.

The association between toll-like receptor 4 polymorphisms and diabetic retinopathy in Chinese patients with type 2 diabetes

PURPOSE

Diabetic retinopathy (DR) is one of the secondary microvascular complications of type 2 diabetes mellitus. Persistent inflammation and impaired neovascularisation may be important contributors to the development of DR. A recent study showed that toll-like receptor 4 (TLR4) polymorphisms were associated with DR. The present study was designed to determine whether single-nucleotide polymorphisms (SNPs) in the TLR4 gene were associated with DR in a Chinese Han population.

MATERIALS AND METHODS

Three SNPs (rs10759931, rs1927911 and rs1927914) in the TLR4 gene were chosen as candidate SNPs. Genomic DNA from type 2 diabetes patients and healthy controls were genotyped for the above-mentioned genetic variations through the use of PCR restriction fragment length polymorphism assay. Data were analysed by χ(2) analysis.

RESULTS

The results showed that the three analysed polymorphisms in the TLR4 gene were in Hardy-Weinberg equilibrium, both in the patients and in the controls. In the type 2 diabetes group, a significantly higher frequency of the C allele of rs1927914 was observed in patients with type 2 diabetes than that in controls. The result showed that the frequencies of the TT genotype and the T allele of rs1927914 were significantly decreased in patients with type 2 diabetes. Significantly increased frequencies of the CC genotype and the C allele of rs1927911 were observed in patients with type 2 diabetes. In the DR group, the C allele of rs1927914 was significantly increased in the DR group compared with that of the control. The frequencies of the CC genotype and the C allele of rs1927911 tended to be higher in patients with DR than in the healthy controls. However, no difference was found when the Bonferroni correction was applied. No difference was detected between patients and controls with regard to all haplotypes.

CONCLUSIONS

This study suggested that rs1927914 and rs1927911 were associated with type 2 diabetes mellitus and that rs1927914 was associated with susceptibility to DR in a Han Chinese population.

TLR2, TLR4 and CD86 gene polymorphisms in recurrent aphthous stomatitis

BACKGROUND

Recurrent aphthous stomatitis (RAS) is an inflammatory disease induced by genetic and environmental factors. Toll-like receptor (TLR) and CD86 are essential components for innate immunity and cellular immune response. We aimed to determine whether inheritance of specific TLR2, TLR4and CD86 gene polymorphisms are associated with RAS.

METHODS

Ninety-six patients with RAS and 153 controls were studied. Eight SNPs were genotyped using PCR-RFLP technique; four in TLR2 gene: rs4696480, rs3804100, rs121917864, rs5743708; three in TLR4 gene: rs10759931, rs4986790 rs1927911; and one in CD86 gene rs17281995. Association was assessed by logistic regression analysis. Linkage disequilibrium (LD) was assessed using the Haploview program.

RESULTS

Significant increase in inheritance of A allele (OR = 1.6, P = 0.01) and AA genotype (OR = 3.89, P = 0.01) of TLR4 rs10759931 was observed in cases. TLR4rs1927911 C allele and CC genotype were also increased (OR = 1.60 and 2.78 respectively); however, this was not statistically significant (P = 0.02 and 0.03 respectively). TLR2 and CD86 did not show association with RAS.

CONCLUSIONS

This is the first study to investigate the association of TLR and CD86 with RAS. We found a significant association between TLR4 rs10759931 polymorphism and RAS. Confirmatory studies in other populations and functional investigations are needed to determine the role of TLR4 in RAS.

Global footprints of purifying selection on Toll-like receptor genes primarily associated with response to bacterial infections in humans

Toll-like receptors (TLRs) are directly involved in host–pathogen interactions. Polymorphisms in these genes are associated with susceptibility to infectious diseases. To understand the influence of environment and pathogen diversity on the evolution of TLR genes, we have undertaken a large-scale population-genetic study. Our study included two hunter–gatherer tribal populations and one urbanized nontribal population from India with distinct ethnicities (n = 266) and 14 populations inhabiting four different continents (n = 1,092). From the data on DNA sequences of cell-surface TLR genes, we observed an excess of rare variants and a large number of low frequency haplotypes in each gene. Nonsynonymous changes were few in every population and the commonly used statistical tests for detecting natural selection provided evidence of purifying selection. The evidence of purifying selection acting on the cell-surface TLRs of the innate immune system is not consistent with Haldane’s theory of coevolution of immunity genes, at least of innate immunity genes, with pathogens. Our study provides evidence that genes of the cell-surface TLRs, that is, TLR2 and TLR4, have been so optimized to defend the host against microbial infections that new mutations in these genes are quickly eliminated.

Epigenetic influences on associations between air pollutants and lung function in elderly men: the normative aging study

BACKGROUND

Few studies have been performed on pulmonary effects of air pollution in the elderly--a vulnerable population with low reserve capacity--and mechanisms and susceptibility factors for potential effects are unclear.

OBJECTIVES

We evaluated the lag structure of air pollutant associations with lung function and potential effect modification by DNA methylation (< or ≥ median) at 26 individual CpG sites in nine candidate genes in a well-characterized cohort of elderly men.

METHODS

We measured forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1), and blood DNA methylation one to four times between 1999 and 2009 in 776 men from the Normative Aging Study. Air pollution was measured at fixed monitors 4 hr to 28 days before lung function tests. We used linear mixed-effects models to estimate the main effects of air pollutants and effect modification by DNA methylation.

RESULTS

An interquartile range (IQR) increase in subchronic exposure (3 to 28 days cumulated), but not in acute exposure (during the previous 4 hr, or the current or previous day), to black carbon, total and nontraffic particles with aerodynamic diameter ≤ 2.5 μm (PM2.5), carbon monoxide, and nitrogen dioxide was associated with a 1-5% decrease in FVC and FEV1 (p < 0.05). Slope estimates were greater for FVC than FEV1, and increased with cumulative exposure. The estimates slopes for air pollutants (28 days cumulated) were higher in participants with low (< median) methylation in TLR2 at position 2 and position 5 and high (≥ median) methylation in GCR.

CONCLUSIONS

Subchronic exposure to traffic-related pollutants was associated with significantly reduced lung function in the elderly; nontraffic pollutants (particles, ozone) had weaker associations. Epigenetic mechanisms related to inflammation and immunity may influence these associations.

Macrophage migration inhibitory factor deficiency in chronic obstructive pulmonary disease

The pathogenesis of chronic obstructive pulmonary disease (COPD) remains poorly understood. Cellular senescence and apoptosis contribute to the development of COPD; however, crucial regulators of these underlying mechanisms remain unknown. Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine that antagonizes both apoptosis and premature senescence and may be important in the pathogenesis of COPD. This study examines the role of MIF in the pathogenesis of COPD. Mice deficient in MIF (Mif(-/-)) or the MIF receptor CD74 (Cd74(-/-)) and wild-type (WT) controls were aged for 6 mo. Both Mif(-/-) and Cd74(-/-) mice developed spontaneous emphysema by 6 mo of age compared with WT mice as measured by lung volume and chord length. This was associated with activation of the senescent pathway markers p53/21 and p16. Following exposure to cigarette smoke, Mif(-/-) mice were more susceptible to the development of COPD and apoptosis compared with WT mice. MIF plasma concentrations were measured in a cohort of 224 human participants. Within a subgroup of older current and former smokers (n = 72), MIF concentrations were significantly lower in those with COPD [8.8, 95%CI (6.7-11.0)] compared with those who did not exhibit COPD [12.7 ng/ml, 95%CI (10.6-14.8)]. Our results suggest that both MIF and the MIF receptor CD74 are required for maintenance of normal alveolar structure in mice and that decreases in MIF are associated with COPD in human subjects.

PPARγ agonists regulate tobacco smoke-induced Toll like receptor 4 expression in alveolar macrophages

Background

Peroxisome proliferator-activated receptor-gamma (PPARγ) is a ligand-activated transcription factor that exerts multiple biological effects. Growing evidence suggests that PPARγ plays an important role in inflammation; however, the effects of this transcription factor on the inflammation caused by smoking are unclear.

Methods

We measured the expression of inflammatory cytokines (leukotriene B4, LTB4 and interleukin 8, IL-8), PPARγ and toll-like receptors (TLR2 and TLR4) in alveolar macrophages (AMs) harvested from rats exposed to cigarette smoke (CS) for 3 months in vivo. Some of the rats were pre-treated with rosiglitazone (PPARγ agonist, 3 mg/kg/day, ip), rosiglitazone (3 mg/kg/day, ip) + BADGE (bisphenol A diglycidyl ether, a PPARγ antagonist, 30 mg/kg/day, ig), or BADGE alone (30 mg/kg/day, ig). We also measured the expression of PPARγ, TLR2, TLR4 and nuclear factor-kappaB (NF-κB) in AMs gained from normal rats, which exposed to 5% CSE (cigarette smoke extract) for 12hrs, respectively pretreated with PBS, rosiglitazone (30 uM), rosiglitazone (30 uM) + BADGE (100 uM), 15d-PGJ2 (PPARγ agonist, 5 uM), 15d-PGJ2 (5 uM) + BADGE (100 uM), or BADGE (100 uM) alone for 30 min in vitro.

Results

In vivo, rosiglitazone counteracted CS-induced LTB4 and IL-8 release and PPARγ downregulation, markedly lowering the expression of TLR4 and TLR2. In vitro, both rosiglitazone and 15d-PGJ2 inhibited CS-induced inflammation through the TLR4 signaling pathway.

Conclusions

These results suggest that PPARγ agonists regulate inflammation in alveolar macrophages and may play a role in inflammatory diseases such as COPD.

Oxidants in Acute and Chronic Lung Disease

Oxidants play an important role in homeostatic function, but excessive oxidant generation has an adverse effect on health. The manipulation of Reactive Oxygen Species (ROS) can have a beneficial effect on various lung pathologies. However indiscriminate uses of anti-oxidant strategies have not demonstrated any consistent benefit and may be harmful. Here we propose that nuanced strategies are needed to modulate the oxidant system to obtain a beneficial result in the lung diseases such as Acute Lung Injury (ALI) and Chronic Obstructive Pulmonary Disease (COPD). We identify novel areas of lung oxidant responses that may yield fruitful therapies in the future.

Non-essential role for TLR2 and its signaling adaptor Mal/TIRAP in preserving normal lung architecture in mice

Myeloid differentiation factor 88 (MyD88) and MyD88-adaptor like (Mal)/Toll-interleukin 1 receptor domain containing adaptor protein (TIRAP) play a critical role in transducing signals downstream of the Toll-like receptor (TLR) family. While genetic ablation of the TLR4/MyD88 signaling axis in mice leads to pulmonary cell death and oxidative stress culminating in emphysema, the involvement of Mal, as well as TLR2 which like TLR4 also signals via MyD88 and Mal, in the pathogenesis of emphysema has not been studied. By employing an in vivo genetic approach, we reveal here that unlike the spontaneous pulmonary emphysema which developed in Tlr4^−/− mice by 6 months of age, the lungs of Tlr2^−/− mice showed no physiological or morphological signs of emphysema. A more detailed comparative analysis of the lungs from these mice confirmed that elevated oxidative protein carbonylation levels and increased numbers of alveolar cell apoptosis were only detected in Tlr4^−/− mice, along with up-regulation of NADPH oxidase 3 (Nox3) mRNA expression. With respect to Mal, the architecture of the lungs of Mal^−/− mice was normal. However, despite normal oxidative protein carbonylation levels in the lungs of emphysema-free Mal^−/− mice, these mice displayed increased levels of apoptosis comparable to those observed in emphysematous Tlr4^−/− mice. In conclusion, our data provide in vivo evidence for the non-essential role for TLR2, unlike the related TLR4, in maintaining the normal architecture of the lung. In addition, we reveal that Mal differentially facilitates the anti-apoptotic, but not oxidant suppressive, activities of TLR4 in the lung, both of which appear to be essential for TLR4 to prevent the onset of emphysema.

Association of Toll-like receptor 4 polymorphisms with diabetic foot ulcers and application of artificial neural network in DFU risk assessment in type 2 diabetes patients

The Toll-Like receptor 4 (TLR4) plays an important role in immunity, tissue repair, and regeneration. The objective of the present work was to evaluate the association of TLR4 single nucleotide polymorphisms (SNPs) rs4986790, rs4986791, rs11536858 (merged into rs10759931), rs1927911, and rs1927914 with increased diabetic foot ulcer (DFU) risk in patients with type 2 diabetes mellitus (T2DM). PCR-RFLP was used for genotyping TLR4 SNPs in 125 T2DM patients with DFU and 130 controls. The haplotypes and linkage disequilibrium between the SNPs were determined using Haploview software. Multivariate linear regression (MLR) and artificial neural network (ANN) modeling was done to observe their predictability for the risk of DFU in T2DM patients. Risk genotypes of all SNPs except rs1927914 were significantly associated with DFU. Haplotype ACATC (P value = 9.3E − 5) showed strong association with DFU risk. Two haplotypes ATATC (P value = 0.0119) and ATGTT (P value = 0.0087) were found to be protective against DFU. In conclusion TLR4 SNPs and their haplotypes may increase the risk of impairment of wound healing in T2DM patients. ANN model (83%) is found to be better than the MLR model (76%) and can be used as a tool for the DFU risk assessment in T2DM patients.

Role of the Toll Like receptor (TLR) radical cycle in chronic inflammation: possible treatments targeting the TLR4 pathway

Activation of the Toll-like receptor 4 (TLR4) complex, a receptor of the innate immune system, may underpin the pathophysiology of many human diseases, including asthma, cardiovascular disorder, diabetes, obesity, metabolic syndrome, autoimmune disorders, neuroinflammatory disorders, schizophrenia, bipolar disorder, autism, clinical depression, chronic fatigue syndrome, alcohol abuse, and toluene inhalation. TLRs are pattern recognition receptors that recognize damage-associated molecular patterns and pathogen-associated molecular patterns, including lipopolysaccharide (LPS) from gram-negative bacteria. Here we focus on the environmental factors, which are known to trigger TLR4, e.g., ozone, atmosphere particulate matter, long-lived reactive oxygen intermediate, pentachlorophenol, ionizing radiation, and toluene. Activation of the TLR4 pathways may cause chronic inflammation and increased production of reactive oxygen and nitrogen species (ROS/RNS) and oxidative and nitrosative stress and therefore TLR-related diseases. This implies that drugs or substances that modify these pathways may prevent or improve the abovementioned diseases. Here we review some of the most promising drugs and agents that have the potential to attenuate TLR-mediated inflammation, e.g., anti-LPS strategies that aim to neutralize LPS (synthetic anti-LPS peptides and recombinant factor C) and TLR4/MyD88 antagonists, including eritoran, CyP, EM-163, epigallocatechin-3-gallate, 6-shogaol, cinnamon extract, N-acetylcysteine, melatonin, and molecular hydrogen. The authors posit that activation of the TLR radical (ROS/RNS) cycle is a common pathway underpinning many "civilization" disorders and that targeting the TLR radical cycle may be an effective method to treat many inflammatory disorders.