Association of Clara cell 10-kDa protein, spontaneous regression and sarcoidosis

Surfactant protein D, Club cell protein 16, Pulmonary and activation-regulated chemokine, C-reactive protein, and Fibrinogen biomarker variation in chronic obstructive lung disease

Chronic obstructive pulmonary disease (COPD) is a multifaceted condition that cannot be fully described by the severity of airway obstruction. The limitations of spirometry and clinical history have prompted researchers to investigate a multitude of surrogate biomarkers of disease for the assessment of patients, prediction of risk, and guidance of treatment. The aim of this review is to provide a comprehensive summary of observations for a selection of recently investigated pulmonary inflammatory biomarkers (Surfactant protein D (SP-D), Club cell protein 16 (CC-16), and Pulmonary and activation-regulated chemokine (PARC/CCL-18)) and systemic inflammatory biomarkers (C-reactive protein (CRP) and fibrinogen) with COPD. The relevance of these biomarkers for COPD is discussed in terms of their biological plausibility, their independent association to disease and hard clinical outcomes, their modification by interventions, and whether changes in clinical outcomes are reflected by changes in the biomarker.

Distribution of Clara cell secretory protein expression in the tracheobronchial airways of rhesus monkeys

Clara cell secretory protein (CCSP) is a protective lung protein that is believed to have antioxidant, immunomodulatory, and anticarcinogenic properties; to be present in all adult mammals; and to be well conserved in rodents, humans, and nonhuman primates. The rationale for this study is to define the distribution and abundance of CCSP in the airway epithelium and lavage fluid of the adult rhesus monkey and to provide information for evaluating CCSP as a marker of Clara cells and as a biomarker of lung health. Lung tissue and lavage fluid from 3-yr-old rhesus monkeys were examined using histopathology and immunohistochemistry. Proximal bronchi, midlevel bronchi, and terminal/respiratory bronchioles were compared for immunohistochemical localization of CCSP in three-dimensional whole mounts as well as in paraffin and Araldite sections. Immunoreactive CCSP was found in nonciliated cells throughout the airway epithelium. Proximal and midlevel airways had the highest labeling. CCSP decreased in distal airways, and respiratory bronchioles had little to no CCSP. CCSP in the most distal airways was in tall cuboidal cells adjacent to the pulmonary artery. Although a large number of cells were present in the terminal bronchioles that would be classified as Clara cells based on morphology (nonciliated cells with apical protrusions), only a small number stained positively for immunoreactive CCSP. Semiquantitative analysis of Western blots indicated that changes in lavage CCSP are consistent with, and may be predictive of, overall CCSP levels in the airway epithelium in this primate species that is phylogenetically similar to humans.

Genetics of sarcoidosis: candidate genes and genome scans

Human leukocyte antigen class II allele associations and T-cell receptor beta chain bias in sarcoidosis suggest a specific disease-triggering antigen exposure in a genetically susceptible host. The cause of sarcoidosis has been elusive, but genetics provides one of the few promising avenues to further our understanding. We review the association studies and genome scans used to identify the genes involved in sarcoidosis.

In vivo Cre/loxP mediated recombination in mouse Clara cells

In small airways, Clara cells are the main epithelial cell type and play an important physiological role in surfactant production, protection against environmental agents, regulation of inflammatory and immune responses in the respiratory system. Thus, Clara cells are involved in lung homeostasis and pathologies like asthma, Chronic Obstructive Pulmonary Diseases (COPD) or cancers. To date, Clara cells implication in these pathological processes remains largely enigmatic. The engineering of a transgenic strain mouse allowing specific gene invalidation in Clara cells may be of interest to improve our knowledge about the genes involved in these diseases. By using the Cre/loxP strategy we report the engineering of a transgenic mouse strain with expression of Cre recombinase under the control of the Clara Cell Secretory Protein (CCSP) promoter. Specific staining and immuno-histochemistry performed after breeding with reporter mice revealed that CCSP drives a functional Cre expression specifically in Clara cells. This mouse strain is a powerful tool for Cre-loxP-mediated conditional recombination in the lung and represents a new tool to study Clara cell physiology.

Association of interleukin-8 with inflammatory and innate immune components in bronchoalveolar lavage of children with chronic respiratory diseases

BACKGROUND

The host inflammatory response and innate immunity play a complex role in respiratory diseases.

METHODS

We evaluated the levels of inflammatory mediators and antibacterial proteins in children who required bronchoscopy and bronchoalveolar lavage fluid (BALF) for clinical indications such as chronic tracheostomy (n=15) and chronic suppurative lung disease (n=8).

RESULTS

Our results suggested the presence of interleukin-1beta (IL-1beta) and IL-8 as major inflammatory mediators in BALF samples. The level of the antibacterial protein sIgA was higher than lactoferrin and lysozyme. BALF IL-8 levels significantly correlated with the presence of IL-1beta, IL-6, IL-10, IL-16, sIgA and lysozyme. BALF IL-8 levels did not correlate with the levels of immunomodulatory and anti-inflammatory clara cell 10 kDa protein (CC10) or lactoferrin.

CONCLUSION

This study suggests that patients with high levels of BALF IL-8 could potentially have high levels of IL-6, IL-10, IL-16, lysozyme and sIgA. Evaluating the inflammatory mediators (IL-8) in relation to other BALF protein components provides insight into understanding the role of inflammatory mediators in the regulation of host defense and the response to lung inflammation and injury.

Protein composition of apical surface fluid from the human airway cell line Calu-3: effect of ion transport mediators

BACKGROUND

Analysis of the protein components of airway secretions is a potential means of detecting and characterizing biochemical alterations associated with airway diseases.

METHODS

We evaluated airway protein secretions using the airway epithelial cell line Calu-3 grown at an air-liquid interface. To observe changes in apically secreted proteins, we analyzed the protein content of apical surface fluid (ASF) washings of Calu-3 monolayers treated with ion transport mediators.

RESULTS

Immunoassay screening for antibacterial and inflammatory proteins indicated the presence of measurable levels of lysozyme and IL-8 in Calu-3 ASF. RT-PCR and immunoassay studies indicated that Calu-3 cells do not produce clara cell 10 kDa protein (CC10). The total protein secretion of Calu-3 was not altered by bradykinin, but amiloride and adenosine significantly increased Calu-3 protein secretion. Lysozyme secretion was not altered by bradykinin, but amiloride and adenosine significantly reduced lysozyme secretion. IL-8 secretion was not altered by bradykinin or adenosine, but amiloride significantly decreased IL-8 secretion.

CONCLUSION

Our results demonstrate the presence of antibacterial protein lysozyme and the pro-inflammatory cytokine IL-8 in Calu-3 ASF and that ion transport mediators such as bradykinin, amiloride and adenosine influence the secretion of Calu-3 ASF proteins.

The Clara Cell10 Adenine38Guanine Polymorphism and Sarcoidosis Susceptibility in Dutch and Japanese Subjects

CC10 (CC16, uteroglobin) is a pulmonary protein postulated to play a counter regulatory role in sarcoidosis pathogenesis. The adenine38guanine (A38G) polymorphism of the encoding CC10 gene (SCGB1A1) is functional. Recently, an association between the low CC10 producing 38A allele and sarcoidosis susceptibility has been reported in Japanese patients from Hokkaido. The aim of the present study was to confirm this association in a clinically well characterized population of Dutch white and Kyoto Japanese patients with sarcoidosis and control subjects. No difference in genotype or allele frequency was found between patients with sarcoidosis and control subjects in either ethnic population. Remarkably, however, a significant difference was found between the control subjects from Kyoto and Hokkaido, but not between the Japanese groups of patients with sarcoidosis. Furthermore, review of previously published A38G genotyping results showed a consistent difference in CC10 A38G allele frequencies between whites and Japanese subjects. We conclude that the CC10 A38G polymorphism does not influence sarcoidosis susceptibility in Dutch whites or in Japanese subjects from Kyoto. This stresses the importance of studying the influence of polymorphisms on disease susceptibility in multiple ethnically and geographically distinct disease and control populations before reaching conclusions.

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.

Recombinant protein 1/secretoglobin 1A1 participates in the actin polymerization of human platelets

BACKGROUND

Human protein 1 which was originally isolated from pathological urine is identified with clara cell 10 kDa protein and uteroglobin. It has immunomodulatory and anti-inflammatory effects in many vertebrates. Although there have been thorough studies on the structure, molecular biology and biochemical characteristics, the precise mechanism of its biological activities is unknown. The purpose of this research is to clarify the biochemical mechanism of protein 1 through its effect on the platelet aggregation process.

METHODS

Changes in calcium mobilization, actin filament concentrations and functions of integrin alphaIIbbeta3 resulting from platelet stimulation were measured in the presence or absence of recombinant protein 1 (rP1).

RESULTS

Recombinant protein 1 inhibited U46619- and thapsigargin-induced platelet aggregation by preventing store mediated calcium entry (SMCE). The binding of rP1 to resting platelets induced an increase in the actin filament that accompanied the structural changes of alphaIIbbeta3. When rP1-pretreated platelets were activated by thrombin or thapsigargin, the alterations in the actin filament and alphaIIbbeta3 resulting from the stimulation decreased.

CONCLUSION

These results suggest that rP1 inhibits platelet aggregation by participation in the actin polymerization through which SMCE is mediated.

Clara cell impact in air-side activation of CFTR in small pulmonary airways

The Clara cells are nonciliated, nonmucous, secretory cells containing characteristic peptidergic granules; they constitute up to 80% of the epithelial cell population of the distal airways. Despite this exposed histotopology and abundance within the terminal airways where fluid secretion is of pivotal importance, the functional role of the Clara cells remained poorly understood. At the transcriptional, translational, and cellular levels, we provide evidence that the Clara cells are well equipped with the bioactive peptide guanylin and proteins of the cGMP-signaling system including guanylate cyclase C, cGMP-dependent protein kinase II, and cystic fibrosis transmembrane conductance regulator (CFTR) together with the two CFTR scaffolding proteins EBP50/NHERF and E3KARP/NHERF-2 that are essential for proper function of CFTR. Guanylin was localized to secretory granules underneath the apical membrane of Clara cells and was, in addition, detected in high concentrations in bronchoalveolar lavage fluid, predicting release of the peptide luminally into the bronchiolar airways. On the other hand, the guanylin-receptor guanylate cyclase C, CFTR, and proteins linked to CFTR activation and function were all confined to the adluminal membrane of Clara cells, implicating an intriguing air-side route of action of guanylin. Whole-cell patch-clamp recordings in the Clara cell line H441 revealed that guanylin activates CFTR Cl(-) conductance via the cGMP but not the cAMP-signaling pathway. Hence, in the critical location of distal airways in situ, the Clara cells may play the outstanding role of CFTR-dependent regulation of epithelial electrolyte/water secretion through a sophisticated paracrine/luminocrine mode of guanylin-induced CFTR activation.

Bronchoalveolar lavage in interstitial lung disease

Bronchoalveolar lavage (BAL) has become a standard diagnostic procedure for the majority of patients with interstitial disease. The technique is safe, minimally invasive, and reveals specific information in some disorders such as pulmonary alveolar proteinosis, Langerhans cell histiocytosis, alveolar hemorrhage, malignant infiltrates, or dust exposure. Here BAL can often replace lung biopsy. The results of BAL cell differentials with a lymphocytic, a neutrophilic, an eosinophilic, or a mixed cellular pattern can be used as an adjunct to diagnosis. If a BAL finding is compatible with the suspected diagnosis in the context of an appropriate disease history and clinical and radiologic findings, this can then be sufficient for disease confirmation. Recent research focused on the pathogenesis of various types of interstitial lung disorders. In this regard, BAL findings contributed to the characterization of idiopathic pulmonary fibrosis (IPF) as a condition with a predominant T-helper-2 (Th2) cytokine profile, whereas BAL findings in sarcoidosis and hypersensitivity pneumonitis are characterized by a Th1-dominant profile. The clinical value of BAL to assess the activity of disease processes and to provide prognostic information is still under debate. The routine performance of serial BAL is not recommended at present.

Development of an enzyme-linked immunosorbent assay for Clara cell 10-kDa protein: in pursuit of clinical significance of sera in patients with asthma and sarcoidosis

We have produced nine monoclonal antibodies to human CC10/protein-1 and analyzed their characterization. TY-5, TY-7, and TY-8 recognized restricted possible hydrophobic epitopes and their binding to CC10 prevented the other clones from CC10 binding, suggesting that these antibodies induce strong conformational change. TY-1, TY-2, TY-3, TY-6, and 6D4 recognize amino acid residues 61-68 and the presence of disulfide bonds might be essential for epitope expression of these five clones. The best combination was TY-1 and TY-2 in developing an enzyme-linked immunosorbent assay (ELISA), whereas TY-5 was most suitable for immunohistochemistry and immunoblotting. We found significantly lower serum CC10 levels in asthmatic subjects and higher serum CC10 levels in sarcoidosis subjects than in controls. Data of CC10 levels in BAL fluids of sarcoidosis subjects were similar to those in the circulation. CC10-positive epithelial cells were significantly lower in small airways of asthmatic subjects than in controls, and CC10-positive epithelial cells were inversely correlated with T cell and mast cell accumulation in the airways of asthmatic subjects. CC10 may be a downregulator in both Th1- and Th2-mediated chronic inflammatory diseases. The use of these MoAbs and recombinant CC10 is a powerful tool to investigate the clinical roles of CC10/P1 and the structure and function of CC10/P1.

IL-12 and IL-18 are increased and stimulate IFN-gamma production in sarcoid lungs

Sarcoidosis is a systemic chronic granulomatous disease of unknown cause. Recent investigations revealed that the cytokine profile in inflamed lesions of sarcoidosis is Th1 dominant. To obtain better immunopathologic understanding of sarcoidosis, we examined the expression of IL-12 and IL-18 and their roles in IFN-gamma production in pulmonary sarcoidosis. Sarcoid cases had significantly elevated levels of IL-12 (p40 and p70) and IL-18 in bronchoalveolar lavage (BAL) fluids compared with healthy subjects. IL-12 p70 and IL-18 were immunohistochemically expressed in the epithelioid cells and giant cells of sarcoid granulomas. Significant induction of IFN-gamma, IL-12 p70, and IL-18 was observed from sarcoid BAL fluid cells with LPS stimulation, whereas LPS tended to induce only IL-12 p70 in BAL fluid cells from healthy subjects. Sarcoid cases had significantly greater IFN-gamma induction with LPS stimulation than healthy subjects did. IL-18 mRNA expression was observed in freshly isolated sarcoid BAL fluid cells as well as in LPS-stimulated sarcoid BAL fluid cells, but IFN-gamma and IL-12 mRNA expression was observed only in LPS-stimulated BAL fluid cells. Treatment with anti-IL-12- and anti-IL-18-neutralizing Abs significantly inhibited IFN-gamma production from LPS-stimulated BAL fluid cells of sarcoid cases. Coadministration of rIL-12 or rIL-18 induced greater IFN-gamma production in sarcoid BAL fluid cells than in normal BAL fluid cells. We concluded that bioactive IL-12 and IL-18 were produced in sarcoid BAL fluid cells and synergistically induced IFN-gamma production, indicating important cytokines in the Th1 response of sarcoidosis.