The Genetic Predisposition to Interstitial Lung Disease

Redox imbalance and pulmonary function in bleomycin-induced fibrosis in C57BL/6, DBA/2, and BALB/c mice

The development of bleomycin-induced pulmonary fibrosis (BLEO-PF) has been associated with differences in genetic background and oxidative stress status. The authors' aim was to investigate the crosstalk between the redox profile, lung histology, and respiratory function in BLEO-PF in C57BL/6, DBA/2, and BALB/c mice. BLEO-PF was induced with a single intratracheal dose of bleomycin (0.1 U/mouse). Twenty-one days after bleomycin administration, the mortality rate was over 50% in C57BL/6 and 20% in DBA/2 mice, and BLEO-PF was not observed in BALB/c. There was an increase in lung static elastance (p < .001), viscoelastic/inhomogeneous pressure (p < .05), total pressure drop after flow interruption (p < .01), and ΔE (p < .05) in C57BL/6 mice. The septa volume increased in C57BL/6 (p < .05) and DBA/2 (p < .001). The levels of IFN-γ were reduced in C57BL/6 mice (p < .01). OH-proline levels were increased in C57BL/6 and DBA/2 mice (p < .05). SOD activity and expression were reduced in C57BL/6 and DBA/2 mice (p < .001 and p < .001, respectively), whereas catalase was reduced in all strains 21 days following bleomycin administration compared with the saline groups (C57BL/6: p < .05; DBA/2: p < .01; BALB/c: p < .01). GPx activity and GPx1/2 expression decreased in C57BL/6 (p < .001). The authors conclude that BLEO-PF resistance may also be related to the activity and expression of SOD in BALB/c mice.

Correlation of IL-1alpha and IL-4 gene polymorphisms and clinical parameters in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a serious disease characterized with progressive scarring of the lungs in which a genetic background is supposed. We have tested correlation of promotor regions of IL-1alpha and IL-4 gene polymorphisms with clinical parameters in IPF. We investigated the group of 30 patients with IPF. The correlations of vital capacity (VC) and diffusing capacity for carbon monoxide (DL(CO)), bronchoalveolar lavage (BAL) fluid cell counts and high resolution computed tomography (HRCT) alveolar and interstitial scores with different genotypes of IL-4 at (-1098), (-590) and (-33) positions and IL-1 alpha at (-889) position were tested. The PCR method was used for genotyping. The carriers of CT genotype at IL-1 alpha (-889) position had higher VC at the time of diagnosis. The CC genotype at this position was more frequent in patients with higher counts of HLADR+ T lymphocytes in BAL. The GT genotype at IL-4 (-1098) position correlated with higher counts of CD4(+) T lymphocytes, and inversely the TT genotype with higher counts of CD8(+) T lymphocytes in BAL fluid. According to dynamic changes of HRCT score the CT genotype at IL-4 (-33) was more frequent in patients with progressive disease compared to that with stable disease. We assume from our data that the gene polymorphisms of the promotor region of IL-4 at position (-1098) and (-33) and IL-1 alpha at position (-889) are likely to play a pathogenic role in IPF and in modification of its clinical presentation and severity.

Cytokine gene polymorphisms and high-resolution-computed tomography score in idiopathic pulmonary fibrosis

INTRODUCTION

Idiopathic pulmonary fibrosis (IPF) is a serious disease with unknown cause and the influence of cytokine gene polymorphisms is presumed in the etiology and pathogenesis of the disease. We used high-resolution computed tomography (HRCT) as a marker of disease stage and progression and compared the alveolar and interstitial score with IL-1, IL-4, IL-12, IL-1RA and IL-4RA cytokine gene polymorphisms.

SUBJECTS AND METHODS

The IPF patients were all Caucasians from the Czech Republic and consisted of 20 females and 10 males, with a mean age of 65 years, range 36-85. The HRCT results were evaluated by an experienced viewer using the interstitial and alveolar score scales, which were based on the IPF HRCT description system from Gay SE, Kazerooni EA, Tows GB, Lynch JP, Gross BH, Cascade PN, et al. [Idiopathic pulmonary fibrosis. Predicting response to therapy and survival. Am J Respir Crit Care Med 1998;157:1063-72]. We evaluated the polymorphisms of cytokine genes utilizing a PCR with sequence-specific primers method.

RESULTS

The HRCT alveolar score was more pronounced in IL-4 RA (+1902) AG heterozygotes. The HRCT interstitial score was less severe in the IL-12 (-1188) AA homozygotes. According to progression of the HRCT interstitial score, the CC homozygosity at IL-1 RA (mspa 111100), the AA homozygosity at IL-4 RA (+1902) and CC homozygosity at IL-4(+33) positions were more frequent in patients with stable disease compared to those with progressive disease.

CONCLUSIONS

We assume from our data that the polymorphisms of IL-4, IL-4RA, IL-1RA and IL-12 genes (genes of cytokines with regulatory activity) might influence the phenotype of IPF as shown by measurable changes in HRCT investigations.

Functional Prostaglandin-Endoperoxide Synthase 2 Polymorphism Predicts Poor Outcome in Sarcoidosis

RATIONALE

The majority of patients with sarcoidosis resolve their condition; however 5-10% of patients with sarcoidosis develop pulmonary fibrosis with poor prognosis. Prostaglandin-endoperoxide synthase 2 (PTGS2) is a key regulatory enzyme in the synthesis of the antifibrotic agent prostaglandin E(2) and is reduced in sarcoidosis lung. A promoter polymorphism in PTGS2, -765G>C, is reported to reduce its expression.

OBJECTIVES

To investigate if -765G>C is associated with susceptibility to, and poorer outcome within, sarcoidosis and to examine a possible mechanism by which -765G>C reduces PTGS2 expression.

METHODS

We used a case-control design study and genotyped -765G>C in a white British population of 198 patients with sarcoidosis and 166 control subjects. Patients with sarcoidosis were classified before genotyping as having persistent or nonpersistent disease using clinical criteria that included chest radiography staging, need for treatment, lung function, and longitudinal follow-up. Electrophoretic mobility shift assays were used to identify changes in transcription factor binding caused by the -765G>C polymorphism.

RESULTS

Carriage of the -765C allele was strongly associated with susceptibility to sarcoidosis (odds ratio, 2.50; 95% confidence interval, 1.51-4.13; p=0.006) and, within this disease, with poorer outcome (odds ratio, 3.11; 95% confidence interval, 1.35-7.13; p=0.008). The association with sarcoidosis was replicated in a second Austrian population. Electrophoretic mobility shift assays revealed that the -765C allele causes a loss of Sp1/Sp3 transcription factor binding and an increase in Egr-1 binding to the region.

CONCLUSION

Our data suggest that the -765G>C polymorphism identifies individuals who are susceptible to sarcoidosis and, more importantly, at risk of pulmonary fibrotic disease. An altered Sp1/Sp3 binding to the -765 region may contribute to the mechanism by which -765G>C reduces PTGS2 expression.

Th1/Th2 cytokine gene polymorphisms in patients with idiopathic pulmonary fibrosis

We investigated 30 patients with idiopathic pulmonary fibrosis (IPF) and 103 healthy volunteers for the cytokines polymorphisms of the IL-1alpha, IL-1beta, IL-1R, IL-1RA, IL-2, IL-4, IL-6, IL-10, IL-12, tumor necrosis factor-alpha, interferon-gamma, transforming growth factor-beta, IL-1beta, IL-2, IL-4, and IL-4RA genes. The strongest correlation of a genotype with the disease was found for gene polymorphisms at the promotor region of IL-4, where the CT genotypes at the positions (-590) and (-33) were more frequent in the IPF group (P < 0.0001, P(corr) < 0.0022; vs P < 0.0001, P(corr) < 0.0022). Our results support the idea of the pathogenic role of cytokine gene polymorphisms in the etiology and pathogenesis of IPF, with emphasize on the IL-4 promotor gene polymorphisms.

Pulmonary Involvement in Systemic Sclerosis

Scleroderma, also known as progressive systemic sclerosis (SSc), is a multisystem autoimmune disorder characterized by inflammation and fibrosis involving the skin as well as internal organs such as the vasculature, esophagus, and the respiratory tract. Pulmonary involvement consists most often of interstitial fibrosis and pulmonary vascular disease leading to pulmonary arterial hypertension (PAH). Bronchiectasis is an uncommon pulmonary manifestation of systemic sclerosis. Pulmonary hemorrhage with acute renal failure and diffuse alveolar hemorrhage in the absence of a history of renal involvement or penicillamine intake have rarely been reported in patients with systemic sclerosis.On high resolution CT, evidence of interstitial disease is seen in approximately 90% of patients, the main findings being a fine reticular pattern involving the subpleural regions of the lower lobe. Other common findings include ground-glass opacities, honeycombing, and parenchymal micronodules. The most distinctive pulmonary histologic findings in patients with scleroderma are the vascular changes found in PAH in the absence of significant interstitial fibrosis.There is no strong evidence that any drug alters the course of the two main types of lung disease in systemic sclerosis. This apparent failure of therapy may reflect the fact that pulmonary involvement is usually identified at an established or late stage. It has been suggested that, for fibrosing alveolitis, corticosteroids are most effective if given in combination with cyclophosphamide. In some patients with SSc, PAH has been considered as a major cause of morbidity and mortality. Centrally infused prostacyclin (epoprostenol) and its subcutaneously infused analog treprostinil improve hemodynamics, as well as the quality of life and survival in these patients. Iloprost has also shown a positive effect on PAH in SSc patients. More recently, bosentan, an endothelin receptor antagonist, has proved effective in controlling PAH after 6 months' treatment. Sildenafil has been used as a selective pulmonary vasodilator in SSc patients with isolated PAH. This drug decreased mean pulmonary artery pressure and pulmonary vascular resistance, and increased cardiac output, with much improvement of the physical condition of the patients. Lung transplant can be considered as a last option.Clinicians must be aware of the possibility of lung disease in patients with SSc so that it can be treated as early as possible.

Major histocompatibility complex and alveolar epithelial apoptosis in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic disease characterized by fibroblast expansion, and tissue remodeling. It is considered a multifactorial disease but the possible involved genes are largely unknown. Interestingly, studies regarding the possible role of major histocompatibility complex (MHC) are scanty and show contradictory results. In this study, we evaluated the polymorphisms of the MHC, locus HLA-B, -DRB1, and -DQB1 in a cohort of 75 IPF patients and 95 controls by using PCR and hybridization with sequence-specific oligonucleotide probes. In addition, we examined the effect of bronchoalveolar lavage (BAL) from IPF patients with different MHC haplotypes on alveolar epithelial growth rate by WST-1 cell viability assay and on epithelial apoptosis by flow cytometry and by cleaved caspase-3 in cell homogenates. Three haplotypes were significantly increased in IPF: (1) HLA-B*15-DRB1*0101-DQB1*0501 (OR=10.72, CI=1.43-459.6; pC=0.011); (2) HLA-B*52-DRB1*1402-DQB1*0301 (OR=4.42, CI=1.21-24.1; pC=0.024); and (3) HLA-B*35-DRB1*0407-DQB1*0302 (OR=4.73, CI=1.53-19.5; pC=0.005). BAL from patients with the later haplotype significantly reduced epithelial growth rate ( approximately 30%) and caused epithelial cell apoptosis assayed by cleaved caspase-3 (351.7+/-16.5 pg/10(6) cells versus 264+/-24 from controls, and 274+/-36.8 and 256.5+/-10.7 from the other haplotypes; P<0.05), and DNA breaks labeling by flow cytometry (23.7+/-6.9% versus 3.1+/-0.7% from controls, and 6.5+/-0.6% and 7.6+/-1.2% from the other two haplotypes; P<0.01). These findings suggest that some MHC polymorphisms confer susceptibility to IPF, which might be related with the induction of epithelial cell apoptosis, a critical process in the development of the disease.

Interstitial lung disease in children -- genetic background and associated phenotypes

Interstitial lung disease in children represents a group of rare chronic respiratory disorders. There is growing evidence that mutations in the surfactant protein C gene play a role in the pathogenesis of certain forms of pediatric interstitial lung disease. Recently, mutations in the ABCA3 transporter were found as an underlying cause of fatal respiratory failure in neonates without surfactant protein B deficiency. Especially in familiar cases or in children of consanguineous parents, genetic diagnosis provides an useful tool to identify the underlying etiology of interstitial lung disease. The aim of this review is to summarize and to describe in detail the clinical features of hereditary interstitial lung disease in children. The knowledge of gene variants and associated phenotypes is crucial to identify relevant patients in clinical practice.

H2-Ea deficiency is a risk factor for bleomycin-induced lung fibrosis in mice

Pulmonary fibrosis is a significant complication in cancer patients when treated by radiation, e.g., thoracic malignant diseases, or chemotherapeutic agents. Bleomycin is one of the primary drugs used to treat testicular cancer, but the incidence of significant pulmonary fibrosis limits the dose. It is known that susceptibility to bleomycin-induced pulmonary fibrosis is a heritable trait controlled by multiple genes, none of which, however, are yet known. In this study, we used expression profiling and genetic analysis in mouse models of bleomycin-induced pulmonary fibrosis and identified MHC class II antigen Ealpha (H2-Ea) as a risk factor for this disease. We found that a loss-of-function deletion in the H2-Ea gene was linked to susceptibility. A functional test of H2-Ea in transgenic mice showed 100% survival in the transgenic mice compared with 53% in C57BL/10J mice and significantly decreased pulmonary fibrosis from 16.42% (C57BL/10J) to 5.76% (transgenic; P = 1.20e(-8)). These results show that H2-Ea expression protects mice from bleomycin-induced pulmonary fibrosis, which implicates H2-Ea as a candidate susceptibility gene for pulmonary fibrosis.

Connective tissue growth factor is crucial to inducing a profibrotic environment in "fibrosis-resistant" BALB/c mouse lungs

The individual susceptibility to pulmonary fibrosis (PF) remains a mystery, suggesting a role for genetic predisposition. The pathogenesis of PF involves a multitude of factors mediating crosstalk between various tissue components. Some factors, such as transforming growth factor beta, are recognized as key elements in the process, whereas the role of others, such as connective tissue growth factor (CTGF), is unclear. We investigated if Balb/c mice, known to be fibrosis resistant partly due to lack of CTGF induction upon stimulation with bleomycin, can be transformed into fibrosis-sensitive individuals by generation of a CTGF-rich environment using transient overexpression of CTGF by adenoviral gene transfer (AdCTGF). We show that AdCTGF is not sufficient to cause fibrosis, and that bleomycin challenge results in inflammation, but not fibrosis, in Balb/c mouse lungs. This inflammation is accompanied by lower levels of CTGF and tissue inhibitor of metalloproteinase-1 gene expression compared with fibrosis-prone C57BL/6 mice. However, concomitant administration of AdCTGF and bleomycin leads to a persistent upregulation of tissue inhibitor of metalloproteinase-1 gene and a significant fibrotic response in Balb/c similar to that in C57BL/6 mice. We propose that CTGF is an important mediator in the pathogenesis of PF in that it provides a local microenvironment in the lung that causes individual susceptibility. CTGF should be considered as a novel drug target and as a potential marker for identifying individuals at risk.

Polymorphism of Clara cell 10-kD protein gene of sarcoidosis

Clara cell 10-kD protein (CC10) exhibits potent antiinflammatory properties. G38A polymorphism was found in the CC10 gene. We investigated the genetic influence of the allele on the development of sarcoidosis using case control analysis in a Japanese population (265 sarcoidosis cases and 258 control subjects). The A allele frequency in sarcoidosis cases (45.1%) was significantly higher than healthy control subjects (34.9%, p = 0.0002). According to outcomes, we divided 223 patients with follow-up periods of 3 years or more into two subgroups (55 progressive and 168 regressive disease). The A allele frequency in patients with progressive disease was significantly higher than control subjects (odds ratio = 4.55; 95% confidence interval, 2.97-6.97; p < 0.0001), whereas that of regressive disease was not. The A/A genotypes had significantly lower bronchoalveolar lavage fluid CC10 levels than the G/G (nonsmokers, p = 0.0054, and smokers, p = 0.0045) and G/A genotypes (nonsmokers, p = 0.0022, and smokers, p = 0.0402). The reporter gene assay showed significantly lower reporter activities in the presence of interferon-gamma for the 38A construct than the 38G construct (p = 0.0177). The G38A polymorphism in the CC10 gene may influence protein expression and be associated with the development of progressive sarcoidosis.

Transforming growth factor-beta1 gene polymorphisms are associated with disease progression in idiopathic pulmonary fibrosis

Transforming growth factor-beta1 (TGF-beta1) is a cytokine that plays a key role in the development of idiopathic pulmonary fibrosis. There have been reports on the presence of two genetic polymorphisms in the DNA sequence encoding the leader sequence of the TGF-beta1 protein, located in codons 10 and 25. The objective of this study was to investigate the association between TGF-beta1 gene polymorphisms in codons 10 and 25 and the susceptibility to idiopathic pulmonary fibrosis and the progression of the disease. Compared with healthy control subjects (n = 140), patients with idiopathic pulmonary fibrosis (n = 128) showed no significant deviations in genotype or allele frequencies. One hundred and ten patients with idiopathic pulmonary fibrosis were followed up for 30.3 +/- 25 months. The presence of a proline allele at codon 10 was independently associated with a significant increase in alveolar arterial oxygen tension difference during follow-up, after controlling for the effect of treatment (coefficient = 0.59; 95% confidence intervals, 0.23 to 0.96; p = 0.002). These findings suggest that (1) TGF-beta1 gene polymorphisms in codons 10 and 25 do not predispose to the development of idiopathic pulmonary fibrosis; and (2) TGF-beta1 gene polymorphisms may affect disease progression in patients with idiopathic pulmonary fibrosis.