Our long-term objectives are to study mechanisms by which modifier genes affect pulmonary disease severity in patients with cystic fibrosis (CF), with emphasis on the surfactant proteins (SP-), which are produced by lung epithelial cells. SP-A and SP-D play a role in the innate host defense and/or the regulation of inflammatory processes in the lung, and SP-B is essential for normal lung function. Preliminary findings indicate that SP-A genetic variants are associated with disease severity in CF. The overall rationale for the proposed studies is that significant heterogeneity exists in the severity of pulmonary disease in CF patients, even in those that are homozygous for the F508 mutation of the CF transmembrane conductance regulator gene (CFTR). This phenotypic diversity may be related to the genetic heterogeneity of the surfactant protein genes. Genetic variation in the SP-B gene may relate to differences in pulmonary function and genetic variation in SP-A and SP-D may relate to differences in innate host defense function in CF. The overall hypothesis states that SP-A, SP-B, and SP-D are modifiers of pulmonary disease severity in CF and that differences exist among SP-A genetic variants in their ability to modulate phagocytosis of Pseudomonas aeruginosa. In this proposal, we will carry out two major groups of experiments. First, we will study family-based associations by carrying out extended transmission disequilibrium test (ETDT) and/or TDT analyses, of the SP-A, SP-B, and SP-D marker loci, and CF, to determine whether these loci are linked to CF and identify susceptibility SP alleles for CF severity. The entire CF study group as well as a number of subgroups based on CFTR genotype, severity, or other criteria, will be studied. Logistic regression analysis will be used to identify factors that may be of particular significance in CF along with specific genotypes (Aim 1). In the second group of experiments, we will focus on SP-A genetic variants for which preliminary evidence of an association between SP-A alleles and CF severity exists. We will study differences in the ability of SP-A alleles to enhance phagocytosis, by a macrophage-like cell line, of laboratory strains of mucoid and non-mucoid P. aeruginosa grown under different environmental conditions that have been shown to reproduce certain biochemical and functional characteristics found in clinical isolates of P. aeruginosa (Aim 2) and of mucoid and non-mucoid isolates of P. aeruginosa from CF patients (Aim 3). The findings may help identify specific host defense mechanisms involving alleles associated with pulmonary disease severity in CF and develop a useful in vitro model to study the in vivo modifications of P. aeruginosa and its clearance, and provide the basis for further consideration of novel therapeutic strategies to treat CF-related lung disease.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL068947-05
Application #
6927122
Study Section
Special Emphasis Panel (ZHL1-CSR-J (S1))
Program Officer
Banks-Schlegel, Susan P
Project Start
2001-09-30
Project End
2008-08-31
Budget Start
2005-09-01
Budget End
2008-08-31
Support Year
5
Fiscal Year
2005
Total Cost
$351,250
Indirect Cost
Name
Pennsylvania State University
Department
Physiology
Type
Schools of Medicine
DUNS #
129348186
City
Hershey
State
PA
Country
United States
Zip Code
17033
Mikerov, Anatoly N; Umstead, Todd M; Gan, Xiaozhuang et al. (2008) Impact of ozone exposure on the phagocytic activity of human surfactant protein A (SP-A) and SP-A variants. Am J Physiol Lung Cell Mol Physiol 294:L121-30
Tagaram, Hephzibah Rani S; Wang, Guirong; Umstead, Todd M et al. (2007) Characterization of a human surfactant protein A1 (SP-A1) gene-specific antibody;SP-A1 content variation among individuals of varying age and pulmonary health. Am J Physiol Lung Cell Mol Physiol 292:L1052-63
Wang, Guirong; Myers, Catherine; Mikerov, Anatoly et al. (2007) Effect of cysteine 85 on biochemical properties and biological function of human surfactant protein A variants. Biochemistry 46:8425-35
Mikerov, Anatoly N; Wang, Guirong; Umstead, Todd M et al. (2007) Surfactant protein A2 (SP-A2) variants expressed in CHO cells stimulate phagocytosis of Pseudomonas aeruginosa more than do SP-A1 variants. Infect Immun 75:1403-12
Mikerov, Anatoly N; Umstead, Todd M; Huang, Weixiong et al. (2005) SP-A1 and SP-A2 variants differentially enhance association of Pseudomonas aeruginosa with rat alveolar macrophages. Am J Physiol Lung Cell Mol Physiol 288:L150-8