Surfactant Protein A2 (SP-A2) Variants Expressed in CHO Cells Stimulate Phagocytosis of Pseudomonas aeruginosa More than Do SP-A1 Variants

Abstract

Surfactant protein A (SP-A) enhances phagocytosis of Pseudomonas aeruginosa. Two functional genes, SP-A1and SP-A2, encode human SP-A. As we showed before, baculovirus-mediated insect cell-expressed SP-A2 enhances the association of P. aeruginosa with rat alveolar macrophages (rAMs) more than does SP-A1. However, true phagocytosis (internalization) was not shown, and insect cell derived proteins lack or are defective in certain mammalian posttranslational modifications that may be important for SP-A1 and SP-A2 activity and specificity. Here we used SP-A1 (6A 2 , 6A 4 ) and SP-A2 (1A 0 , 1A 1 ) allele variants expressed by CHO (Chinese hamster ovary) mammalian cells to study their effect on association and/or internalization of P. aeruginosa by rAMs and/or human AMs (hAMs) and to study if phagocytosis can be modulated differentially and/or more effectively by CHO cell-expressed SP-A variants than by insect-cell expressed SP-A variants. For cell association and internalization assessments, light microscopy and fluorescence-activated cell sorter analyses were used, respectively. We found the following for the first time.

Polymorphisms in the Surfactant Protein A Gene Are Associated with the Susceptibility to Recurrent Urinary Tract Infection in Chinese Women

“…Moreover, the biologic activity of 19Ala allele variant inhibiting ATP-stimulated PC secretion from alveolar type II cells was higher than 19Val allele (Wang et al 2004). Furthermore, 19Ala allele variant showed greater ability to stimulate phagocytosis of P. aeruginosa (Mikerov et al 2007) and bind to bacterial Re-LPS (Sánchez-Barbero et al 2007) when compared with 19Val allele variant. Furthermore, different SP-A genotypes express different protein levels (Floros and Hoover 1998).…”

“…The SP-A1 alleles differ at codons for amino acids residue 19(Ala19Val), 50(Leu50Val), 62(Pro62Pro), 133(Thr133Thr), 219(Arg219Trp) and the SP-A2 alleles at 4 codons, encoding amino acids residue 9(Thr9Asn), 91(Pro91Ala), 140(Ser140Ser), and 223(Lys223Gln). Though there are only nearly 10 amino acid differences in SP-A1 and SP-A2 allele products, the SP-A2 allele gene products exhibit a more significant effect in biochemical functions than SP-A1 allele gene products (DiAngelo et al 1999;Wang et al 2000;Wang et al 2004;Mikerov et al 2007). Two polymorphisms within SP-D gene have been identified in the exonic sequence: codons corresponding to amino acid residue 11(Thr11Met), 160(Thr160Ala) (DiAngelo et al 1999;Pantelidis et al 2003).…”

Impact of ozone exposure on the phagocytic activity of human surfactant protein A (SP-A) and SP-A variants

“…SP-A has been shown to be involved in the stimulation of chemotaxis of macrophages (62), the enhancement of phagocytosis of bacteria (10,25,36,38,39), the proliferation of immune cells (2,31), the linkage of innate and adaptive immunity (4), and in the modulation of the production of proinflammatory cytokines (3,30,60,61). Genetically modified mice lacking SP-A are more susceptible to challenge with experimental pneumonia than wild-type mice (34).…”

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].…”