Small bowel cyclooxygenase 2 (COX-2) expression in patients with IgA nephropathy.
BACKGROUND
Clinical manifestation of IgA nephropathy (IgAN) strikingly occurs after respiratory tract infections. An intestinal inflammation has also been described. We hypothesized that the intestinal inflammation should manifest itself as an increase in inflammatory cells and mucosal cyclooxygenase 2 (COX-2) expression.


METHODS
By using immunohistochemistry, we determined the phenotype and quantity of inflammatory cells in duodenal biopsy specimens from 17 IgAN patients. Control material comprised 18 patients undergoing gastroscopy because of dyspepsia.


RESULTS
All the biopsy specimens disclosed normal villous architecture. In IgAN, CD3(+) cells and COX-2-positive cells were significantly increased and J chain-producing plasma cells were significantly decreased. CD3(+) cells coexpressed COX-2 protein and COX-2-positive cells also expressed CD45RO antigen. The number of lymphocytes correlated significantly with serum IgA and COX-2-expression with serum IgA and the degree of hematuria. COX-2-positive subepithelial fibroblasts were a conspicuous finding in IgAN. In CD68(+) and CD15(+) cells, a significant increase was seen. Many of these cells also expressed COX-2 protein. CD15(+) positivity correlated significantly with proteinuria in IgAN.


CONCLUSIONS
Our results indicate that small bowel inflammation in IgAN shows itself as an increased number of mucosal inflammatory cells. However, polymeric IgA production is significantly decreased. An increased mucosal COX-2 expression suggests activation of the inflammatory cells and the degree of inflammation significantly correlates with serum IgA and the amount of proteinuria and hematuria. Subepithelial fibroblasts seem also to be involved in the inflammatory reaction.
Honkanen
Teemu
T
Department of Pathology, Tampere University Hospital, Tampere, Finland.
Mustonen
Jukka
J
Kainulainen
Heikki
H
Myllymäki
Juhani
J
Collin
Pekka
P
Hurme
Mikko
M
Rantala
Immo
I
D000328:Adult; D051546:Cyclooxygenase 2; D004386:Duodenum / Q000201:enzymology*; D005260:Female; D005922:Glomerulonephritis, IGA / Q000201:enzymology* / Q000276:immunology; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D007150:Immunohistochemistry; D017493:Leukocyte Common Antigens / Q000032:analysis; D016256:Lewis X Antigen / Q000032:analysis; D008297:Male; D008565:Membrane Proteins; D008875:Middle Aged; D011451:Prostaglandin-Endoperoxide Synthases / Q000032:analysis*
D007070:Immunoglobulin A; D016256:Lewis X Antigen; D008565:Membrane Proteins; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D017493:Leukocyte Common Antigens