Y402H polymorphism of complement factor H affects binding affinity to C-reactive protein.
Complement factor H (FH) is an important regulator of the alternative complement pathway. The Y402H polymorphism within the seventh short consensus repeat of FH was recently shown to be associated with age-related macular degeneration, the most common cause of irreversible blindness in the Western world. We examined the effects of this polymorphism on various FH functions. FH purified from sera of age-related macular degeneration patients homozygous for the FH(402H) variant showed a significantly reduced binding to C-reactive protein (CRP), an acute phase protein, as compared with FH derived from unaffected controls homozygous for the FH(402Y) variant. Strongly reduced binding to CRP was also observed with a recombinant fragment of FH (short consensus repeat 5-7) containing the same amino acid change. Because the interaction of CRP and FH promotes complement-mediated clearance of cellular debris in a noninflammatory fashion, we propose that the reduced binding of FH(402H) to CRP could lead to an impaired targeting of FH to cellular debris and a reduction in debris clearance and enhanced inflammation along the macular retinal pigmented epithelium-choroid interface in individuals with age-related macular degeneration.
Laine
Matti
M
Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki, Haartmaninkatu 3, FI-00014 Helsinki, Finland.
Jarva
Hanna
H
Seitsonen
Sanna
S
Haapasalo
Karita
K
Lehtinen
Markus J
MJ
Lindeman
Nina
N
Anderson
Don H
DH
Johnson
Patrick T
PT
Järvelä
Irma
I
Jokiranta
T Sakari
TS
Hageman
Gregory S
GS
Immonen
Ilkka
I
Meri
Seppo
S
D000368:Aged; D000369:Aged, 80 and over; D002097:C-Reactive Protein / Q000235:genetics / Q000378:metabolism*; D017242:Complement Factor H / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D005260:Female; D006720:Homozygote; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000378:metabolism; D008268:Macular Degeneration / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged; D010857:Pigment Epithelium of Eye / Q000378:metabolism / Q000473:pathology; D011110:Polymorphism, Genetic; D011485:Protein Binding / Q000235:genetics; D012160:Retina / Q000378:metabolism / Q000473:pathology
D017242:Complement Factor H; D002097:C-Reactive Protein