Expression of host defense scavenger receptors in spondylarthropathy.
OBJECTIVE
Reactive arthritis (ReA) is postulated to be caused by a defective host defense against gram-negative bacteria. HLA-B27 could play a role in this process, but does not account for the many HLA-B27 negative patients. The objective of this study was to test the expression of 3 macrophage scavenger receptors (SRs) that are responsible for innate immunity against gram-negative bacteria: SR class A type I (SR-AI), SR-AII, and the macrophage receptor with collagenous structure (MARCO). We postulate that defects in such receptors might also contribute to the host risk factors that increase the predisposition to ReA and perhaps other subtypes of spondylarthropathy (SpA).


METHODS
Peripheral blood, synovial fluid, and synovial tissue samples were obtained from patients with recent Salmonella infection, ReA, other SpA, and rheumatoid arthritis (RA). The expression of SRs receptors was assessed by semiquantitative reverse transcriptase-polymerase chain reaction.


RESULTS
Evaluation of the peripheral blood mononuclear cells (PBMC) from 4 patients who were recently infected with Salmonella, showed that PBMC from 2 patients who developed ReA expressed positive levels of MARCO, while PBMC from 2 patients who recovered from infection without sequelae did not. The synovial fluid mononuclear cells (SFMC) from some ReA patients expressed MARCO, but the levels were only moderate. The level of MARCO in the SFMC from the SpA patient group was low. In marked contrast, MARCO expression was high in almost all samples of RA SFMC. These findings also extended to synovial tissues.


CONCLUSIONS
Expression of the host defense gene MARCO was susceptible to modulation, not only during infections, but also in the inflammatory arthritis conditions RA and SpA. MARCO is a variable to be considered as a candidate factor that might contribute to ReA.
Seta
N
N
University of California Los Angeles, USA.
Granfors
K
K
Sahly
H
H
Kuipers
J G
JG
Song
Y W
YW
Baeten
D
D
Veys
E M
EM
Maksymowych
W
W
Märker-Hermann
E
E
Gu
J
J
Huang
F
F
Kirveskari
J
J
Yu
D T
DT
D000293:Adolescent; D000328:Adult; D016918:Arthritis, Reactive / Q000097:blood; D018955:CD36 Antigens; D017931:DNA Primers / Q000737:chemistry; D005260:Female; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins; D008875:Middle Aged; D000091402:Prohibitins; D012333:RNA, Messenger / Q000378:metabolism; D011971:Receptors, Immunologic / Q000097:blood* / Q000235:genetics; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012480:Salmonella Infections / Q000097:blood; D051117:Scavenger Receptors, Class A; D051122:Scavenger Receptors, Class B; D013167:Spondylitis, Ankylosing / Q000097:blood*; D013582:Synovial Fluid / Q000166:cytology / Q000378:metabolism; D013583:Synovial Membrane / Q000166:cytology / Q000378:metabolism
D018955:CD36 Antigens; D017931:DNA Primers; C490460:MARCO protein, human; D008565:Membrane Proteins; C000717331:PHB2 protein, human; D000091402:Prohibitins; D012333:RNA, Messenger; D011971:Receptors, Immunologic; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; C454739:Scarb1 protein, mouse; D051117:Scavenger Receptors, Class A; D051122:Scavenger Receptors, Class B