Methotrexate modulates the expression of MMP-1 and type 1 collagen in dermal fibroblast.

Methotrexate (MTX), an anti-metabolite and anti-inflammatory drug, has been used to effectively manage and prevent keloids, but its mechanism(s) of action has not been elucidated. Our study sought to evaluate the effect of MTX on the production of key extra cellular matrix components, collagen, and matrix metalloproteinase-1 (MMP-1), produced by fibroblasts and involved in development of fibrosis. The proliferation and viability of cultured human dermal fibroblasts in response to different concentrations of MTX were determined using cell counting and MTT assay, respectively. Western blot analysis was used to determine the levels of both intracellular and secreted type 1 collagen and MMP-1. The results showed no significant changes in the proliferation of fibroblasts treated with 50 ng/ml of MTX as compared to that of control. Under the same experimental conditions, the level of secreted and intracellular type I collagen was markedly reduced and, conversely, the level of MMP-1 increased in treated neonatal, adult, and hypertrophic scar fibroblasts as compared with those of controls. The possible involvement of MTX-induced extracellular signal-regulated kinase 1/2 (ERK1/2) pathway in MMP-1 production was also studied and the result showed an increase in phosphorylated ERK 1/2 in response to MTX treatment. In summary, the findings of this study revealed that MTX significantly reduced collagen production in different strains of fibroblasts derived from neonatal, adult, and hypertrophic scar tissues, while under the same experimental conditions, it increased the expression of MMP-1. As such, our findings validate and identify a potential mechanism through which MTX functions as an anti-fibrogenic factor in treating fibroproliferative disorders.

Functional genetic variation in NFKBIA and susceptibility to childhood asthma, bronchiolitis, and bronchopulmonary dysplasia.

Respiratory diseases are the most frequent chronic illnesses in babies and children. Although a vigorous innate immune system is critical for maintaining lung health, a balanced response is essential to minimize damaging inflammation. We investigated the functional and clinical impact of human genetic variants in the promoter of NFKBIA, which encodes IκBα, the major negative regulator of NF-κB. In this study, we quantified the functional impact of NFKBIA promoter polymorphisms (rs3138053, rs2233406, and rs2233409) on promoter-driven protein expression, allele-specific and total NFKBIA mRNA expression, IκBα protein expression, and TLR responsiveness; mapped innate immune regulatory networks active during respiratory syncytial virus infection, asthma, and bronchopulmonary dysplasia; and genotyped and analyzed independent cohorts of children with respiratory syncytial virus infection, asthma, and bronchopulmonary dysplasia. Genetic variants in the promoter of NFKBIA influenced NFKBIA gene expression, IκBα protein expression, and TLR-mediated inflammatory responses. Using a systems biology approach, we demonstrated that NFKBIA/IκBα is a central hub in transcriptional responses of prevalent childhood lung diseases, including respiratory syncytial virus infection, asthma, and bronchopulmonary dysplasia. Finally, by examining independent pediatric lung disease cohorts, we established that this immunologically relevant genetic variation in the promoter of NFKBIA is associated with differential susceptibility to severe bronchiolitis following infection with respiratory syncytial virus, airway hyperresponsiveness, and severe bronchopulmonary dysplasia. These data highlight the importance of negative innate immune regulators, such as NFKBIA, in pediatric lung disease and begin to unravel common aspects in the genetic predisposition to bronchopulmonary dysplasia, bronchiolitis, and childhood asthma.

Effect of heme oxygenase-1 polymorphisms on lung function and gene expression.

BACKGROUND: Oxidative stress induced by smoking is considered to be important in the pathogenesis of Chronic Obstructive Pulmonary Disease (COPD). Heme oxygenase-1 (HMOX1) is an essential enzyme in heme catabolism that is induced by oxidative stress and may play a protective role as an antioxidant in the lung. We determined whether HMOX1 polymorphisms were associated with lung function in COPD patients and whether the variants had functional effects. METHODS: We genotyped five single nucleotide polymorphisms (SNPs) in the HMOX1 gene in Caucasians who had the fastest (n = 278) and the slowest (n = 304) decline of FEV1 % predicted, selected from smokers in the NHLBI Lung Health Study. These SNPs were also studied in Caucasians with the lowest (n = 535) or the highest (n = 533) baseline lung function. Reporter genes were constructed containing three HMOX1 promoter polymorphisms and the effect of these polymorphisms on H2O2 and hemin-stimulated gene expression was determined. The effect of the HMOX1 rs2071749 SNP on gene expression in alveolar macrophages was investigated. RESULTS: We found a nominal association (p = 0.015) between one intronic HMOX1 SNP (rs2071749) and lung function decline but this did not survive correction for multiple comparisons. This SNP was in perfect linkage disequilibrium with rs3761439, located in the promoter of HMOX1. We tested rs3761439 and two other putatively functional polymorphisms (rs2071746 and the (GT)n polymorphism) in reporter gene assays but no significant effects on gene expression were found. There was also no effect of rs2071749 on HMOX1 gene expression in alveolar macrophages. CONCLUSIONS: We found no association of the five HMOX1 tag SNPs with lung function decline and no evidence that the three promoter polymorphisms affected the regulation of the HMOX1 gene.

Effect of gene environment interactions on lung function and cardiovascular disease in COPD.

BACKGROUND: The objective of this study was to determine if gene-environment interactions between cigarette smoking and interleukin-6 (IL6), interferon-γ (IFNG), interleukin-1ß (IL1B), or interleukin-1 receptor antagonist (IL1RN) single nucleotide polymorphisms are associated with lung function decline and cardiovascular disease in chronic obstructive pulmonary disease (COPD). METHODS: Single nucleotide polymorphisms (SNPs) in IL6, IFNG, IL1B, and IL1RN were genotyped in the Lung Health Study and correlated with rate of decline of forced expiratory volume in 1 second (FEV(1)) over 5 years, baseline FEV(1), serum protein levels, cardiovascular disease, and interactions with smoking. RESULTS: The IL6 rs2069825 single nucleotide polymorphism was associated with the rate of decline of prebronchodilator FEV(1) (P = 0.049), and was found to have a significant interaction (P = 0.004) with mean number of cigarettes smoked per day. There was also a significant interaction of IFNG rs2069727 with smoking on prebronchodilator (P = 0.008) and postbronchodilator (P =0.01) FEV(1.) The IL6 polymorphism was also associated with cardiovascular disease in heterozygous individuals (P = 0.044), and was found to have a significant interaction with smoking (P = 0.024). None of the genetic variants were associated with their respective serum protein levels. CONCLUSION: The results suggest interactions of IL6 rs2069825 and IFNG rs2069727 single nucleotide polymorphisms with cigarette smoking on measures of lung function. The IL6 rs2069825 single nucleotide polymorphism also interacted with smoking to affect the risk of cardiovascular disease in COPD patients.