Michele Zorzetto

The receptor for advanced glycation end products and its ligands: a new inflammatory pathway in lung disease?

The binding of the receptor for advanced glycation end products (RAGE) with its ligands begins a sustained period of cellular activation and inflammatory signal amplification in different tissues and diseases. This binding could represent an as yet uninvestigated pathway of inflammatory reaction in the lung, where the presence of the receptor has been largely documented and advanced glycation end products (AGEs) are produced by nonenzymatic glycation and oxidation of proteins and lipids, driven by smoke and pollutants exposure or inflammatory stress. We immunohistochemically assessed the expression of RAGE and of its major proinflammatory ligands, N-ɛ-carboxy-methyl-lysine, S100B and S-100A12 in normal lung and in non-neoplastic lung disorders including smoke-related airway disease, granulomatous inflammation, postobstructive damage and usual interstitial pneumonia. In normal lung low expression of the receptor was observed in bronchiolar epithelia, type II pneumocytes, macrophages and some endothelia. S100A12 and S100B were expressed, respectively, in granulocytes and in dendritic cells. Carboxy-methyl-lysine was present in bronchiolar epithelia and macrophages. In all pathological conditions associated with inflammation and lung damage overexpression of both the receptor and of AGEs was observed in bronchiolar epithelia, type II alveolar pneumocytes, alveolar macrophages and endothelia. RAGE overexpression was more evident in epithelia associated with inflammatory cell aggregates. Fibroblasts in usual interstitial pneumonia expressed both the receptor and AGEs. The number of S100A12 and S100B immunoreactive inflammatory cells was variable. S100A12 was also expressed in mononuclear inflammatory cells and in activated epithelia. The activation of the inflammatory pathway controlled by the RAGE is not specific of a single lung disease, however, it may be relevant as a nonspecific pathway of sustained inflammation in lung tissue, and on this basis therapeutic approaches based on receptor blockage can be envisaged.

Serum levels and genotype distribution of α1-antitrypsin in the general population

Rationale α1-Antitrypsin (AAT) deficiency is one of the commonest rare respiratory disorders worldwide. Diagnosis, assessment of risk for developing chronic obstructive pulmonary disease (COPD), and management of replacement therapy require the availability of precise and updated ranges for protein serum levels. Objective This paper aims to provide ranges of serum AAT according to the main genotype classes in the general population. Methods The authors correlated mean AAT serum levels with the main SERPINA1 variants (M1Ala/M1Val (rs6647), M3 (rs1303), M2/M4 (rs709932), S (rs17580) and Z (rs28929474)) in 6057 individuals enrolled in the Swiss Cohort Study on Air Pollution and Lung Diseases in Adults (SAPALDIA) cohort. Results The following ranges (5th–95th percentile) of AAT were found in the serum (g/litre): 1.050–1.640 for PI*MM, 0.880–1.369 for PI*MS, 0.730–1.060 for PI*SS, 0.660–0.997 for PI*MZ and 0.490–0.660 for PI*SZ. There was very little overlap in AAT serum levels between genotype classes generally not believed to confer an enhanced health risk (MM and MS) and those associated with an intermediate AAT deficiency and a potentially mildly enhanced health risk (SS, MZ). Conclusion This work resulted in three important findings: technically updated and narrower serum ranges for AAT according to PI genotype; a suggestion for a population-based ‘protective threshold’ of AAT serum level, used in decision-making for replacement therapy; and more precise ranges framing the intermediate AAT deficiency area, a potential target for future primary prevention.

SERPINA1 Gene Variants in Individuals from the General Population with Reduced α1-Antitrypsin Concentrations

BACKGROUND Individuals with severe deficiency in serum alpha(1)-antitrypsin (AAT) concentrations are at high risk for developing chronic obstructive pulmonary disease (COPD), whereas those carrying the PI*MZ genotype are at slightly increased risk. Testing appropriate subgroups of the population for AAT deficiency (AATD) is therefore an important aspect of COPD prevention and timely treatment. We decided to perform an exhaustive investigation of SERPINA1 gene variants in individuals from the general population with a moderately reduced serum AAT concentration, because such information is currently unavailable. METHODS We determined the Z and S alleles of 1399 individuals enrolled in the Swiss Cohort Study on Air Pollution and Lung Diseases in Adults (SAPALDIA) with serum AAT concentrations < or = 1.13 g/L and submitted 423 of these samples for complete exon 2-->5 sequencing. RESULTS We found that 900 of 1399 samples (64%), carried the normal PI*MM genotype, whereas 499 samples (36%) carried at least 1 SERPINA1 deficiency variant. In the subpopulations in which AAT concentrations ranged from > 1.03 to < or = 1.13 and from > 0.93 to < or = 1.03 g/L, individuals with the PI*MM genotype represented the majority (86.5% and 53.8%, respectively). The PI*MS genotype was predominant (54.9%) in the AAT range of 0.83 to 0.93 g/L, whereas PI*MZ represented 76.4% in the AAT range of > 0.73 to < or = 0.83 g/L. CONCLUSIONS This analysis provided a detailed molecular definition of intermediate AATD, which would be helpful in the diagnostic setting.

Tumour necrosis factor family genes in a phenotype of COPD associated with emphysema

Genetic factors are believed to play a role in the individual susceptibility to chronic obstructive pulmonary disease (COPD). Tumour necrosis factor (TNF) family genes have been widely investigated but inconsistent results may lie either in the genetic heterogeneity of populations or in the poor phenotype definition. A genetic study was performed using a narrower phenotype of COPD. The authors studied 86 healthy smokers and 63 COPD subjects who were enrolled based on irreversible airflow obstruction (forced expiratory volume in one second/forced vital capacity <70% predicted) and a diffusing capacity for carbon monoxide <50% predicted (moderate-to-severe COPD associated with pulmonary emphysema). The following polymorphisms were investigated: TNF-308, the biallelic polymorphism located in the first intron of the lymphotoxin‐α gene, and exon 1 and exon 6 of the TNF receptor 1 and 2 genes, respectively. No significant deviations were found concerning the four polymorphisms studied between the two populations. The authors confirm that the tumour necrosis factor family genes, at least for the polymorphisms investigated, are not major genetic risk factors for chronic obstructive pulmonary disease in Caucasians, either defined in terms of emphysema (this study) or airflow obstruction (previous studies). Nevertheless, the authors would like to emphasise the importance of narrowing the phenotype in the search for genetic risk factors in chronic obstructive pulmonary disease.

Inflammation and Atherosclerosis: The Role of TNF and TNF Receptors Polymorphisms in Coronary Artery Disease

Inflammation plays an important role in the pathogenesis of atherosclerosis and coronary syndromes; moreover, various lines of evidence suggest that genetic factors contribute significantly to the risk of coronary artery disease (CAD). Through its effects on endothelial function, coagulation, insulin resistance and lipid metabolism, the proinflammatory cytokine TNF could be involved in cardiovascular pathophysiology. The aim of our study is to analyze whether TNF gene promoter (-308 G/A; −857 G/A) and TNF receptor polymorphisms (TNFR1 MspA1 I exon 1 and TNFR2 Nla III exon 6) show involvement in CAD predisposition in a group of Italian patients compared with healthy controls. Genotyping was performed by PCR-RFLP. Consecutive Italian patients with angiographically proven CAD (n= 248) were compared with controls (n=241), matched for age, sex and geographical origins. CAD patients showed a higher frequency of the TNF −308 A allele than healthy controls (p=0.046). After stratification according to risk factors for CAD, our analysis revealed that CAD patients with diabetes (p=0.042) and CAD patients without hypertension (p=0.0495) displayed a higher frequency of the TNF −308 AA genotype compared with healthy controls. Our data stress the inflammatory nature of CAD and show a possible involvement of TNF −308G/A promoter polymorphisms in the predisposition to the development of this disease. The less frequent A allele seems to be a predisposing factor for development of CAD in particular pathological settings associated with the disease itself, such as diabetes.

A large kindred of pulmonary fibrosis associated with a novel ABCA3 gene variant

BackgroundInterstitial lung disease occurring in children is a condition characterized by high frequency of cases due to genetic aberrations of pulmonary surfactant homeostasis, that are also believed to be responsible of a fraction of familial pulmonary fibrosis. To our knowledge, ABCA3 gene was not previously reported as causative agent of fibrosis affecting both children and adults in the same kindred.MethodsWe investigated a large kindred in which two members, a girl whose interstitial lung disease was first recognized at age of 13, and an adult, showed a diffuse pulmonary fibrosis with marked differences in terms of morphology and imaging. An additional, asymptomatic family member was detected by genetic analysis. Surfactant abnormalities were investigated at biochemical, and genetic level, as well as by cell transfection experiments.ResultsBronchoalveolar lavage fluid analysis of the patients revealed absence of surfactant protein C, whereas the gene sequence was normal. By contrast, sequence of the ABCA3 gene showed a novel homozygous G > A transition at nucleotide 2891, localized within exon 21, resulting in a glycine to aspartic acid change at codon 964. Interestingly, the lung specimens from the girl displayed a morphologic usual interstitial pneumonitis-like pattern, whereas the specimens from one of the two adult patients showed rather a non specific interstitial pneumonitis-like pattern.ConclusionsWe have detected a large kindred with a novel ABCA3 mutation likely causing interstitial lung fibrosis affecting either young and adult family members. We suggest that ABCA3 gene should be considered in genetic testing in the occurrence of familial pulmonary fibrosis.

Targeting EGFR in non-small-cell lung cancer: Lessons, experiences, strategies

Cancer is a genetic disease and this concept is now widely exploited by both scientists and clinicians to design new targeted molecules. Indeed many data have already allowed us to ameliorate not only our knowledge about cancer onset, but also about patients treatment. Correlation between mutations in cancer alleles and drug response is a key point to identify drugs that match the genetic profile of each individual tumors. On the other hand, experience derived from inhibition of tyrosine kinase receptors has pointed out that targeted treatment is really successful only in a small subset of tumors. The latter are eventually addicted to those genetic alterations which are responsible for receptors activation and for the continued expression of their signalling. Overall these observations provide a strong rationale for a molecular-based diagnosis and patients selection for targeted therapies. This review analyses the current state of the art of molecularly-tailored pharmacological approach to lung cancer, one of the biggest killers among human solid tumors. Main relevance is addressed to genetic lesions activating the EGFR pathway transducers, focusing on their role as markers of targeted drug response.

The Pro12Ala polymorphism of peroxisome proliferator-activated receptor-γ2 gene is associated with plasma levels of soluble RAGE (Receptor for Advanced Glycation Endproducts) and the presence of peripheral arterial disease

OBJECTIVES Recent evidences suggest that the activation of peroxisome proliferator-activated receptor (PPAR)-gamma2, which plays an important role in vascular homeostasis, also regulates the expression of the Receptor for Advanced Glycation End products (RAGE). In turn, low levels of soluble RAGE (sRAGE) have recently emerged as a valuable biomarker of vascular inflammation. The potential alterations in sRAGE concentrations in peripheral arterial disease (PAD), however, have not been yet investigated. The aim of the present study was to clarify whether the Pro12Ala polymorphism of the PPAR-gamma2 gene is related to plasma sRAGE levels and the presence of PAD in nondiabetic Italian individuals. DESIGN AND METHODS A total of 201 patients with PAD and 201 PAD-free control subjects were investigated. Genotyping of the Pro12Ala polymorphism of the PPAR-gamma2 gene was performed by means of PCR-RFLPs. Plasma sRAGE levels were determined by ELISA. RESULTS Subjects carrying at least one Ala12 allele of the PPAR-gamma2 gene had lower sRAGE levels (all p values<0.001). The prevalence rate of the Ala12 allele was significantly higher in PAD patients (14.0%) than in controls (8.0%, p=0.009). In multivariate logistic regression analysis after adjustment for potential confounders, the Ala12 allele was significantly and independently associated with the risk of PAD (OR=1.57, 95% CI=1.11-2.65, p=0.021). CONCLUSIONS Our data indicate that the Ala12 allele of the PPAR-gamma2 gene is associated with lower levels of the soluble decoy receptor sRAGE and the presence of PAD.

A Novel Method for Rapid Genotypic Identification of Alpha 1-Antitrypsin Variants

Myotonic dystrophy type 2 (DM2) lacks the expansion on chromosome 19q13 present in DM1 and is characterized by a mutation on 3q21. It has been shown that the DM2 mutation is a huge [CCTG]n repeat expansion in intron 1 of the zinc finger protein 9 (ZNF9) gene. The longest normal allele observed has a ∼30 CCTG repeat, whereas the range of expansion is extremely variable, starting from 75 up to 11,000 CCTGs. Direct analysis by Southern blot, after restriction enzyme digestion of genomic DNA, was the first method chosen for studying the DM2 mutation. However, the expansion size and the elevated grade of somatic instability have limited the sensitivity of the test to approximately 80% of known carriers. We developed a long PCR-formatted protocol, which involves a single genomic in vitro amplification, followed by agarose gel electrophoresis and oligospecific hybridization. We were able to detect normal alleles and expanded ZNF9 alleles, starting from low amounts of genomic DNA (≥1 ng) in virtually all the DM2 patients analyzed, obtaining a molecular detection rate of 100%. This method is quick, sensitive, and reproducible, and it reduces the cost of diagnostic laboratory processing for DM2 diagnosis.

Incomplete expression of epithelial–mesenchymal transition markers in idiopathic pulmonary fibrosis

The hypothesis that epithelial-mesenchymal transition (EMT) contributes to the formation of fibroblast foci (FF), which are the histological hallmark and the site of active disease progression of Idiopathic Pulmonary Fibrosis (IPF), has not yet received a conclusive demonstration. Cells undergoing EMT lose epithelial features and acquire mesenchymal markers and morphology. Cadherin expression switch (from E to N) is one of the first events in EMT. We investigated the immunohistochemical expression of E- and N-cadherin, vimentin, fibronectin, laminin-5-γ2, α-smooth muscle actin, and fibroblast-specific protein-1 involved in EMT in 20 IPF lung biopsies, focusing on metaplastic squamous cells of bronchial basal origin, positive for laminin-5-γ2 and ΔNp63/p40, that cover FF. The results were compared with organizing pneumonia, reactive squamous cell metaplasia of bronchiolar epithelia, and squamous cell carcinoma. Bronchiolar basal metaplastic cells in IPF partially lost E-cadherin and expressed vimentin and fibronectin. Hyperplastic pneumocytes in IPF and controls coexpressed E-cadherin and N-cadherin, and were weakly positive for lam5-γ2. Reactive squamous cell metaplasia did not show any mesenchymal markers. Squamous cell carcinoma only expressed lam5-γ2. In IPF lungs, we observed two epithelial cell populations with a different expression profile of markers involved in EMT. Although neither hyperplastic pneumocytes nor bronchial basal cells showed evidence of complete EMT, only the latter seem to be specific for UIP and might have a role in its development.