SP-A1 and SP-A2 variants differentially enhance association of Pseudomonas aeruginosa with rat alveolar macrophages.
Chronic airway inflammation caused by Pseudomonas aeruginosa is an important feature of cystic fibrosis (CF). Surfactant protein A (SP-A) enhances phagocytosis of P. aeruginosa. Two genes, SP-A1 and SP-A2, encode human SP-A. We hypothesized that genetically determined differences in the activity of SP-A1 and SP-A2 gene products exist. To test this, we studied association of a nonmucoid P. aeruginosa strain (ATCC 39018) with rat alveolar macrophages in the presence or absence of insect cell-expressed human SP-A variants. We used two trios, each consisting of SP-A1, SP-A2, and their coexpressed SP-A1/SP-A2 variants. We tested the 6A(2) and 6A(4) alleles (for SP-A1), the 1A(0) and 1A alleles (for SP-A2), and their respective coexpressed SP-A1/SP-A2 gene products. After incubation of alveolar macrophages with P. aeruginosa in the presence of the SP-A variants at 37 degrees C for 1 h, the cell association of bacteria was assessed by light microscopy analysis. We found 1) depending on SP-A concentration and variant, SP-A2 variants significantly increased the cell association more than the SP-A1 variants (the phagocytic index for SP-A1 was approximately 52-95% of the SP-A2 activity); 2) coexpressed variants at certain concentrations were more active than single gene products; and 3) the phagocytic index for SP-A variants was approximately 18-41% of the human SP-A from bronchoalveolar lavage. We conclude that human SP-A variants in vitro enhance association of P. aeruginosa with rat alveolar macrophages differentially and in a concentration-dependent manner, with SP-A2 variants having a higher activity compared with SP-A1 variants.
Mikerov
Anatoly N
AN
Dept. of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA.
Umstead
Todd M
TM
Huang
Weixiong
W
Liu
Wenlei
W
Phelps
David S
DS
Floros
Joanna
J
D000483:Alleles; D000818:Animals; D002478:Cells, Cultured; D014644:Genetic Variation; D006801:Humans; D007313:Insecta; D016676:Macrophages, Alveolar / Q000187:drug effects / Q000382:microbiology*; D008297:Male; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification / Q000502:physiology*; D037662:Pulmonary Surfactant-Associated Protein A / Q000031:analogs & derivatives* / Q000235:genetics* / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D037662:Pulmonary Surfactant-Associated Protein A; C445842:SFTPA1 protein, human; C445843:SFTPA2 protein, human