SP-A1 and SP-A2 variants differentially enhance association ofPseudomonas aeruginosawith rat alveolar macrophages

Abstract

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 cellexpressed 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°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 ϳ52-95% 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 ϳ18 -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.

Characterization of a human surfactant protein A1 (SP-A1) gene-specific antibody; SP-A1 content variation among individuals of varying age and pulmonary health

“…Moreover, qualitative and quantitative differences have been observed in vitro between the SP-A1 and SP-A2 genes (22,36,57,60,(77)(78)(79)(80)(81), pointing to the possibility that the overall functional activity of SP-A may depend on the relative SP-A1-to-SP-A2 levels rather than on the total SP-A content. To address this possibility, it .…”

“…More than 30 alleles have been characterized for these two genes, with four SP-A1 alleles (6A, 6A 2 , 6A 3 , and 6A 4 ) and six SP-A2 alleles (1A, 1A 0 , 1A 1 , 1A 2 , 1A 3 , and 1A 5 ) most frequently observed in the general population (10,14,16,40,67). Although a high level of sequence similarity is shared among the SP-A genes and their corresponding alleles, in vitro studies have identified both qualitative (22,36,57,60,77,80,81) and quantitative (24,35,38,46,56,69,70,78,79) differences between the two genes.Qualitative differences between the SP-A1 and SP-A2 genes include functional, structural, and biochemical differences. Functionally, SP-A2 exhibits a higher level of activity than SP-A1 in its ability to enhance TNF-␣ and IL-8 production by the macrophage-like THP-1 cell line (80, 81), phagocytosis of Pseudomonas aeruginosa by rat alveolar macrophages (57), and secretion of phosphatidylcholine by type II alveolar cells (77).…”

“…Functionally, SP-A2 exhibits a higher level of activity than SP-A1 in its ability to enhance TNF-␣ and IL-8 production by the macrophage-like THP-1 cell line (80,81), phagocytosis of Pseudomonas aeruginosa by rat alveolar macrophages (57), and secretion of phosphatidylcholine by type II alveolar cells (77). Structurally, circular dichroic spectroscopy studies have shown SP-A2 to be more stable than SP-A1 (22).…”

Significance of surfactant proteins in the diagnosis of therapeutic diseases

“…включают их способность стимулировать фагоцитоз [12,14], ин-гибировать секрецию сурфактанта [15], стимулировать продук-цию α-фактора некроза опухоли (TNF-α) [16], как и различия в их аггрегации и олигомеризации [15].…”

“…Показано, что SP-A воздействует на рост и жизнеспособность микроорга-низмов, повышая проницаемость микробной клеточной мембра-ны [3], регулирует механизмы иммунной защиты в легких путем связывания звеньев врожденного и приобретенного компонен-тов иммунитета [4], стимулирует хемотаксис макрофагов [5], вли-яет на пролиферацию клеток иммунного ответа и на продукцию провоспалительных цитокинов [6,7], повышает продукцию ре-активных оксидантов [8], регулирует продукцию оксида азота [9], стимулирует фагоцитоз [10][11][12].…”