The association between the C-509T and T869C polymorphisms of TGF-β1 gene and the risk of asthma: a meta-analysis

The Role of Transforming Growth Factor-β (TGF-β) in Asthma and Chronic Obstructive Pulmonary Disease (COPD)

Asthma and chronic obstructive pulmonary disease (COPD) represent chronic inflammatory respiratory disorders that, despite having distinct pathophysiological underpinnings, both feature airflow obstruction and respiratory symptoms. A critical component in the pathogenesis of each condition is the transforming growth factor-β (TGF-β), a multifunctional cytokine that exerts varying influences across these diseases. In asthma, TGF-β is significantly involved in airway remodeling, a key aspect marked by subepithelial fibrosis, hypertrophy of the smooth muscle, enhanced mucus production, and suppression of emphysema development. The cytokine facilitates collagen deposition and the proliferation of fibroblasts, which are crucial in the structural modifications within the airways. In contrast, the role of TGF-β in COPD is more ambiguous. It initially acts as a protective agent, fostering tissue repair and curbing inflammation. However, prolonged exposure to environmental factors such as cigarette smoke causes TGF-β signaling malfunction. Such dysregulation leads to abnormal tissue remodeling, marked by excessive collagen deposition, enlargement of airspaces, and, thus, accelerated development of emphysema. Additionally, TGF-β facilitates the epithelial-to-mesenchymal transition (EMT), a process contributing to the phenotypic alterations observed in COPD. A thorough comprehension of the multifaceted role of TGF-β in asthma and COPD is imperative for elaborating precise therapeutic interventions. We review several promising approaches that alter TGF-β signaling. Nevertheless, additional studies are essential to delineate further the specific mechanisms of TGF-β dysregulation and its potential therapeutic impacts in these chronic respiratory diseases.

Unveiling the TGF- β1 paradox: Significant implication of TGF- β1 promoter variants and its mRNA and protein expression in atopic dermatitis

BACKGROUND

Atopic Dermatitis (AD) is a chronic inflammatory skin disorder with evidence of lichenification in later stages. There is mounting evidence supporting the role of TGF- β1 in mediating inflammation as well as subsequent tissue remodeling, often resulting in fibrosis. Given the role of genetic variants in the differential expression of TGF-β1 in various diseases, this study seeks to ascertain the role of TGF-β1 promoter variants (rs1800469 and rs1800468) in AD susceptibility, as well as their association with TGF- β1 mRNA expression, TGF- β1 serum levels and skin prick test positivity in Atopic Dermatitis patients.

METHODS

An aggregate of 246 subjects including 134 AD cases and 112 matched healthy controls were genotyped for TGF-β1 promoter polymorphisms by PCR-RFLP. TGF- β1 mRNA was quantified by quantitative Real-Time PCR (qRT-PCR), Vitamin-D levels by chemiluminescence, and serum TGF- β1, and total IgE levels were determined by ELISA. In-vivo allergy testing was performed for the evaluation of allergic reactions to house dust mites and food allergens.

RESULTS

A higher frequency of TT genotypes of rs1800469 (OR = 7.7, p = 0.0001) and GA+AA genotypes of rs1800468 (OR-4.4, p < 0.0001) were observed in AD cases than those in controls. Haplotype analysis demonstrated that TG haplotype carriers had an increased risk of AD (p = 0.013). Quantitative analysis revealed a significant upregulation of both mRNA (p = 0.0002) and serum levels (p < 0.0001) of TGF- β1 with a substantial positive correlation between them (Correlation coefficient=0.504; p = 0.01). Moreover, serum TGF-β1 levels were associated with quality of life (p = 0.03), the severity of the disease (p = 0.03), and House dust mite allergy (p = 0.01) whereas TGF-β1 mRNA levels positively correlated with disease severity(p = 0.02). Stratification analysis revealed that the TT genotype of rs1800469 was associated with higher IgE levels (p = 0.01) and eosinophil percentage(p = 0.007) whereas the AA genotype of rs1800468 correlated with elevated serum IgE levels (p = 0.01). Besides, no significant association of genotypes with mRNA and serum expression of TGF-β1 was observed.

CONCLUSION

Our study indicates that TGF-β1 promoter SNPs bear a significant risk of AD development. Moreover, upregulation of TGF-β1 mRNA and serum levels and their association with disease severity, quality of life, and HDM allergy suggests its role as a diagnostic/prognostic biomarker that could help in the development of new therapeutic and prevention strategies.

TGFβ1 single-nucleotide polymorphism C-509T alters mucosal cell function in pediatric eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a chronic Th2 antigen-driven disorder associated with tissue remodeling. Inflammation and remodeling lead to esophageal rigidity, strictures, and dysphagia. TGFβ1 drives esophageal remodeling including epithelial barrier dysfunction and subepithelial fibrosis. A functional SNP in the TGFβ1 gene that increases its transcription (C-509T) is associated with elevated numbers of esophageal TGFβ1-expressing cells. We utilized esophageal biopsies and fibroblasts from TT-genotype EoE children to understand if TGFβ1 influenced fibroblast and epithelial cell function in vivo. Genotype TT EoE esophageal fibroblasts had higher baseline TGFβ1, collagen1α1, periostin, and MMP2 (p < 0.05) gene expression and distinct contractile properties compared with CC genotype (n = 6 subjects per genotype). In vitro TGFβ1 exposure caused greater induction of target gene expression in genotype CC fibroblasts (p < 0.05). Esophageal biopsies from TT-genotype subjects had significantly less epithelial membrane-bound E-cadherin (p < 0.01) and wider cluster distribution at nanometer resolution. TGFβ1 treatment of stratified primary human esophageal epithelial cells and spheroids disrupted transepithelial resistance (p < 0.001) and E-cadherin localization (p < 0.0001). A TGFβ1-receptor-I inhibitor improved TGFβ1-mediated E-cadherin mislocalization. These data suggest that EoE severity can depend on genotypic differences that increase in vivo exposure to TGFβ1. TGFβ1 inhibition may be a useful therapy in subsets of EoE patients.

Establishment of a fluorescent PCR melting curve method for detecting asthma susceptibility using gene SNP typing

Objective: To develop a detection method for single nucleotide polymorphisms (SNPs) of bronchial asthma (BA) susceptibility genes (IL-13, IL-33, and GSDMA) based on fluorescence PCR melting curves.Methods: Peripheral blood samples from 33 patients with BA were collected. DNA was extracted, and positive plasmids were constructed. Probes and primers for fluorescence polymerase chain reaction (PCR) were designed according to IL-13, IL-33, and GSDMA sequences, and the SNPs were separately detected by gene sequencing and fluorescence PCR melting curve.Results: The system was successfully divided into 3 SNPs, including IL-13, IL-33, and GSDMA, and a comparison of sequencing methods showed that the results were completely consistent. The lowest detection limit was 1 ng/reaction, the sensitivity and specificity were 100%, and this method had high repeatability (CV = 2.8%).Conclusion: The fluorescence PCR melting curve method is suitable for the rapid and accurate classification of SNPs. The method is economical, simple, and efficient, and is suitable for the screening of the susceptible gene SNPs in a large-scale population of patients with BA.

Genetic Mechanisms of Asthma and the Implications for Drug Repositioning

Asthma is a chronic disease that is caused by airway inflammation. The main features of asthma are airway hyperresponsiveness (AHR) and reversible airway obstruction. The disease is mainly managed using drug therapy. The current asthma drug treatments are divided into two categories, namely, anti-inflammatory drugs and bronchodilators. However, disease control in asthma patients is not very efficient because the pathogenesis of asthma is complicated, inducing factors that are varied, such as the differences between individual patients. In this paper, we delineate the genetic mechanisms of asthma, and present asthma-susceptible genes and genetic pharmacology in an attempt to find a diagnosis, early prevention, and treatment methods for asthma. Finally, we reposition some clinical drugs for asthma therapy, based on asthma genetics.

Linkage and Genetic Association in Severe Asthma

A significant body of work in the genetics of asthma currently exists. However, current knowledge has not been clarifying in understanding the pathophysiology of asthma and therapeutic treatment of the disease. Severe asthma in adults and children is a significant burden in relation to disproportionate disease morbidity, mortality, and health utilization. This disease phenotype is not well understood; current effective treatment regimens are limited. Genetic studies may lead to improved understanding of the pathophysiology of severe asthma and identification of relevant subsets, which allow more targeted and effective therapies and the realization of Precision Medicine in asthma.

Influence of the Polymorphism C-509T in the TGFB1 Gene Promoter on the Response to Montelukast

Transforming growth factor beta 1 (TGFB1) is a multifunctional cytokine with a key role in asthma airway inflammation and remodeling. Since elevated levels of this cytokine in airways might be associated with response to asthma therapy, the aim of this study was to investigate whether the presence of the polymorphism C-509T in the promoter of the TGFB1 gene is associated with response to montelukast. A group of 102 asthmatic patients was genotyped for the presence of the C-509T polymorphism by DNA sequencing and subjected to induced sputum sampling. Cells from sputum samples and BEAS 2B cells were treated with montelukast and endogenous TGFB1 expression was measured by quantitative real-time polymerase chain reaction. The promoter activity was analyzed by luciferase assays in BEAS 2B cells transfected with constructs carrying variants -509C and -509T of the TGFB1 gene promoter. After treatment with montelukast, the decrease in TGFB1 gene expression was greater for the -509TT genotype (58.9%) than for the -509CC and -509CT genotypes (49.6% and 31.8%, respectively) (P = 0.071). In BEAS 2B cells, expression of endogenous TGFB1 was reduced by about 27% after montelukast treatment, while luciferase activity of both promoter variants was increased after montelukast treatment (-509C allele: 48.3%, P = 0.060; and -509T allele: 100.5%, P = 0.062). A more intensive response was registered in the promoter containing the -509T allele, which had 135% higher activity than the -509C variant (P = 0.035). This study showed that the presence of the -509T allele in the TGFB1 promoter might modulate effects of montelukast on TGFB1 gene expression, but future studies are necessary, taking into consideration other genetic and nongenetic factors. It is of potential importance for clinical management of asthma to clarify the influence of the C-509T polymorphism on the response to treatment with montelukast.

Atorvastatin has a protective effect in a mouse model of bronchial asthma through regulating tissue transglutaminase and triggering receptor expressed on myeloid cells-1 expression

Airway remodeling in asthma contributes to airway hyperreactivity, loss of lung function and persistent symptoms. Current therapies do not adequately treat the structural airway changes associated with asthma. Statin drugs have improved respiratory health and their therapeutic potential in asthma has been tested in clinical trials. However, the mechanism of action of statins in this context has remained elusive. The present study hypothesized that atorvastatin treatment of ovalbumin-exposed mice attenuates early features of airway remodeling via a mevalonate-dependent mechanism. BALB/c mice were sensitized with ovalbumin and atorvastatin was delivered via oral gavage prior to each ovalbumin exposure. Reverse transcription-semi-quantitative polymerase chain reaction (RT-semi-qPCR), ELISA and western blot analysis were used to assess the expression of a number of relevant genes, including tissue transglutaminase (tTG), triggering receptor expressed on myeloid cells (TREM)-1, nuclear factor erythroid 2-related factor (Nrf) 2, hypoxia-inducible factor (HIF)-1α, transforming growth factor (TGF)-β1, matrix metalloproteinase (MMP)-9 and tissue inhibitors of metalloproteinases (TIMP)-1 in lung tissue. α-Smooth muscle actin (α-SMA) activity was measured by immunohistochemistry. Airway hyperresponsiveness, lung collagen deposition, airway wall area, airway smooth muscle thickness and lung pathology were also assessed. Atorvastatin treatment led to downregulation of tTG and TREM-1 expression in lung tissue after ovalbumin sensitization, blocked the activity of MMP-9, vascular endothelial growth factor, nuclear factor-κB p65, α-SMA, HIF-α and TGF-β1 and up-regulated Nrf2 expression. Furthermore, the number of lymphocytes and eosinophils in the atorvastatin group was significantly lower than that in the control group. In addition, airway hyperresponsiveness, lung collagen deposition, airway wall area, airway smooth muscle thickness and pathological changes in the lung were significantly decreased in the atorvastatin group, and tumor necrosis factor-α, interleukin (IL)-8, IL-13 and IL-17 in serum were significantly decreased. Histological results demonstrated the attenuating effect of atorvastatin on ovalbumin-induced airway remodeling in asthma. In conclusion, the present study indicated that atorvastatin significantly alleviated ovalbumin-induced airway remodeling in asthma by downregulating tTG and TREM-1 expression. The marked protective effects of atorvastatin suggest its therapeutic potential in ovalbumin-induced airway remodeling in asthma treatment.

An updated meta-analysis of transforming growth factor-β1 gene: Three well-characterized polymorphisms with asthma

The association between TGF-β1 polymorphisms and asthma risk has been widely reported, but results were controversial. We performed this meta-analysis based on the Preferred Reporting Items for Systematic Reviews and meta-analyses statement (PRISMA). Electronic database of Pub Med, Web of Science, CBM, and CNKI were searched for eligible articles published up to September, 2013. The effect summary odds ratio (OR) and 95% confidence intervals were obtained. Finally, a total of 20 articles were identified, 17 studies with 3694 cases and 5613 controls for C-509T polymorphism, 7 studies with 1109 cases and 1098 controls for T869C polymorphism and 5 studies with 849 cases and 829 controls for G915C polymorphism. For C-509T, significant associations with asthma were found in Asians (TT+TC vs. CC: P=0.004, OR=1.43, 95%CI=1.12-1.81, P_{heterogeneity}=0.001) and in Caucasians (P=0.05, OR=1.16, 95%CI=1.00-1.34, P_{heterogeneity}=0.36). With respect to T869C, a small significant association was observed in overall analysis of allele contrasts(C vs. T: OR=1.14, 95%CI: 1.01-1.29, P=0.03) and homozygote comparison (CC vs. TT: OR=1.29, 95%CI: 1.00-1.65, P=0.05), but no significant risks were found among Caucasian population and Asian population. For G915C polymorphism, no significant association with asthma risk was demonstrated in overall analysis and subgroup analyses according to ethnicity for all genetic models. This meta-analysis suggested that TGF-β1 C-509T and T869C polymorphisms may be risk factors for asthma.

Broide DH, Aceves SS. The TGFβ1 Promoter SNP C-509T and Food Sensitization Promote Esophageal Remodeling in Pediatric Eosinophilic Esophagitis

BACKGROUND

Eosinophilic esophagitis (EoE) is a chronic antigen mediated disease associated with substantial esophageal remodeling and fibrosis. The functional TGFβ1 promoter SNP C-509 associates with renal fibrosis and asthma. The effect of TGFβ1 genotype and EoE severity or potential gene-environment interactions have not been previously reported in EoE.

METHODS

Genotype at TGFβ1 C-509T and remodeling was analyzed in 144 subjects with EoE. The severity of remodeling and inflammation was analyzed in the context of IgE sensitization to food antigens and C-509T genotype.

RESULTS

The TGFβ1 promoter C-509 genotypes CC, CT, and TT were 35%, 52%, and 13%, respectively. Sixty-six percent of subjects were sensitized to foods by positive skin prick test (SPT) or serum specific IgE. TT genotype subjects had significantly more TGFβ1 (CC subjects = 1300 per mm2; TT = 2250 per mm2) (p<0.05) and tryptase (CC subjects = 145 per mm2: TT = 307 per mm2) (p<0.05) positive cells and higher epithelial remodeling scores (2.4 vs 3.7, p<0.001) than CC subjects. The differences in TGFβ1 and tryptase positive cells as well as fibrosis were significantly increased when there was concurrent food sensitization. Food sensitization alone did not associate with any parameters of inflammation or remodeling.

CONCLUSIONS

Our data support a gene-environment interaction between food and genotype at C-509 that modulates disease severity in EoE. Since EoE subjects often continue to consume foods to which they are sensitized, these findings may have clinical relevance for disease management.

Short-term exposure to particulate air pollution and risk of myocardial infarction: a systematic review and meta-analysis

A growing number of studies have associated short-term exposure to ambient particulate matter air pollution (PM) and risk of specific cardiovascular events, just as myocardial infarction (MI). However, the results of the recent studies were inconsistent; therefore, a systematic review and meta-analysis was performed. To synthetically quantify the association between short-term exposure to PM and risk of MI, a meta-analysis was conducted to combine the estimates of effect for a relationship between short-term exposure to PM10, PM2.5 (particulate matter ≤ 10 μm, 2.5 μm in diameter) and risk of MI. Electronic database searches for all relevant published studies were updated in January 2015. And, a random-effects model was performed to estimate pooled relative risk (RR) and 95 % confidence intervals (95 % CI). Thirty-one published observational epidemiological studies were identified. Risk of MI was significantly associated with per 10 μg/m(3) increment in PM10 (OR = 1.005; 95 % CI 1.001-1.008) and PM2.5 (OR = 1.022; 95 % CI 1.015-1.030). The risk of PM2.5 exposure was relatively greater than PM10. In the subgroup analysis by study design, location, quality score, and lag exposure, the results were basically consistent with the former overall results in PM2.5 but slightly changed in PM10. Short-term exposure to particulate matter (PM2.5, PM10) was a risk factor for MI, and the results further confirmed the discovery in the previous meta-analysis.

Genetic variants in TNFα, TGFB1, PTGS1 and PTGS2 genes are associated with diisocyanate-induced asthma

Diisocyanates are the most common cause of occupational asthma, but risk factors are not well defined. A case-control study was conducted to investigate whether genetic variants in inflammatory response genes (TNFα, IL1α, IL1β, IL1RN, IL10, TGFB1, ADAM33, ALOX-5, PTGS1, PTGS2 and NAG-1/GDF15) are associated with increased susceptibility to diisocyanate asthma (DA). These genes were selected based on their role in asthmatic inflammatory processes and previously reported associations with asthma phenotypes. The main study population consisted of 237 Caucasian French Canadians from among a larger sample of 280 diisocyanate-exposed workers in two groups: workers with specific inhalation challenge (SIC) confirmed DA (DA(+), n = 95) and asymptomatic exposed workers (AW, n = 142). Genotyping was performed on genomic DNA, using a 5' nuclease PCR assay. After adjusting for potentially confounding variables of age, smoking status and duration of exposure, the PTGS1 rs5788 and TGFB1 rs1800469 single nucleotide polymorphisms (SNP) showed a protective effect under a dominant model (OR = 0.38; 95% CI = 0.17, 0.89 and OR = 0.38; 95% CI = 0.18, 0.74, respectively) while the TNFα rs1800629 SNP was associated with an increased risk of DA (OR = 2.08; 95% CI = 1.03, 4.17). Additionally, the PTGS2 rs20417 variant showed an association with increased risk of DA in a recessive genetic model (OR = 6.40; 95% CI = 1.06, 38.75). These results suggest that genetic variations in TNFα, TGFB1, PTGS1 and PTGS2 genes contribute to DA susceptibility.

Maternal exposure to fine particulate matter (PM2.5) and pregnancy outcomes: a meta-analysis

A growing body of evidence has investigated the association between maternal exposure to PM2.5 (particulate matter with aerodynamic diameter 2.5 μm) during pregnancy and adverse pregnancy outcomes. However, the results of those studies are not consistent. To synthetically quantify the relationship between maternal exposure to PM2.5 during pregnancy and pregnancy outcomes (the change in birth weight, low birth weight (LBW), preterm birth (PTB), small for gestational age (SGA), and stillbirth), a meta-analysis of 25 published observational epidemiological studies that met our selection criteria was conducted. Results suggested a 10 μg/m(3) increase in PM2.5 was positively associated with LBW (odds ratio (OR) = 1.05; 95 % confidence interval (CI), 1.02-1.07), PTB (OR = 1.10; 95 % CI, 1.03-1.18), and SGA (OR = 1.15; 95 % CI, 1.10-1.20) based on entire pregnancy exposure, and pooled estimate of decrease in birth weight was 14.58 g (95 % CI, 9.86-19.31); however, there was no evidence of a statistically significant effect of per 10 μg/m(3) increase in PM2.5 exposure on the risk of stillbirth (OR = 1.18; 95 % CI, 0.69-2.04). With respect to three different gestation periods, no significant risks were found in PTB, stillbirth, and the first trimester on the change of birth weight with a 10 μg/m(3) increase in PM2.5. In this study, a comprehensive quantitative analysis of the results show that PM2.5 can increase the risk of LBW, PTB, and SGA; pregnant women need to take effective measures to reduce PM2.5 exposure.

Transforming growth factor β and severe asthma: a perfect storm

Asthma is a chronic inflammatory airway disease involving complex interplay between resident and infiltrative cells, which in turn are regulated by a wide range of host mediators. Identifying useful biomarkers correlating with clinical symptoms and degree of airway obstruction remain important to effective future asthma treatments. Transforming growth factor β (TGF-β) is a major mediator involved in pro-inflammatory responses and fibrotic tissue remodeling within the asthmatic lung. Its role however, as a therapeutic target remains controversial. The aim of this review is to highlight its role in severe asthma including interactions with adaptive T-helper cells, cytokines and differentiation through regulatory T-cells. Associations between TGF-β and eosinophils will be addressed and the effects of genetic polymorphisms of the TGF-β1 gene explored in the context of asthma. We highlight TGF-β1 as a potential future therapeutic target in severe asthma including its importance in identifying emerging clinical phenotypes in asthmatic subjects who may be suitable for individualized therapy through TGF-β modulation.