Factor H in Porcine Seminal Plasma Protects Sperm against Complement Attack in Genital Tracts

Abstract

We found that factor H (FH) exists in porcine seminal plasma. Purified FH strongly inhibited serum alternative pathway complement activation against lipopolysaccharide. The molecular weight, pI, and heparin-binding activity of the purified protein were different from those of purified FH from porcine serum. The complement regulatory activity of seminal plasma FH was ϳ2-fold stronger than that of serum FH. Treatment of purified serum FH with sialidase and N-glycosidase F gave almost the same results as those of seminal plasma FH. The deletion of sialic acid from the carbohydrate chains of both FHs contributed to heparin-binding and complement regulatory activities. Results of reverse transcriptase-PCR, Western blot analysis, and immunohistochemistry showed that seminal plasma FH is mainly secreted from epithelial cells of the seminal vesicle in male genital tracts. FH was also detected in the outer acrosomal region of ejaculated sperm by immunofluorescence staining, and found that the purified FH from the sperm membrane has the same complement regulatory activity as that of seminal plasma FH. The ejaculated sperm possessing FH in the outer acrosomal region considerably evaded complement attack. We also found that there is strong complement activity in fluids from female genital tract ducts. These findings indicate that FH bound to the outer acrosomal region and soluble FH play important roles in protecting sperm against complement attack in male and female genital tracts.

Characterization of the porcine seminal plasma proteome comparing ejaculate portions

“…Regarding the bioinformatics analysis, it is noticeable that only 20 of the 374 proteins regulate immune responses in the female genital tract [11,25], facilitating sperm transport and fertilization. Many of the identified SP-proteins show catalytic activity, specifically hydrolase activity, and some of them would also indirectly be related with reproductive functions, as occurs with Acrosin.…”

Complement control protein factor H: The good, the bad, and the inadequate

“…Factor H (formerly known as β1H) is an abundant serum glycoprotein that is expressed constitutively in the liver (Adinolfi et al, 1981; Schwaeble et al, 1987) and can be also expressed locally by a variety of cell types including retinal pigment epithelial cells, endothelial cells, epithelial cells, platelets, and mesenchymal stem cells, among others (Brooimans et al, 1990; Chen et al, 2007; Licht et al, 2009; Sakaue et al, 2010; Tu et al, 2010). The serum concentration of factor H is ~ 500 μg/ml, although it can vary widely from 116–562 μg/ml depending on genetic and environmental factors (Esparza-Gordillo et al, 2004; de Cordoba and de Jorge, 2008).…”

Desialylation of Spermatozoa and Epithelial Cell Glycocalyx Is a Consequence of Bacterial Infection of the Epididymis

“…Factor H on cell membranes is essential to remove activated complement factor 3b from cellular surfaces to prevent perforation of host cell membranes and limit tissue damage. As shown recently, complement factor H is an important component of seminal plasma, as it protects spermatozoa against such a complement attack in the female reproductive tract (33). Thus, hyposialylation of spermatozoa and other host cells may result in a deficit of sialic acid-dependent factor H binding and, thus, less protection against the activated complement system.…”