Evidence for a differential expression of fibronectin splice forms ED-A and ED-B in Crohn's disease (CD) mucosa.
OBJECTIVE
Fibronectin (FN) is an essential factor for the induction of migration of primary colonic lamina propria fibroblasts (CLPF). The FN isoform ED-A is an important inducer of migration. Recently, we have shown that CLPF isolated from inflamed Crohn's disease (CD) mucosa migrated significantly less than control CLPF. We, therefore, investigated changes in FN or integrin expression that could be relevant for CLPF migration.


METHODS
mRNA of control-CLPF and CLPF isolated from fibrotic mucosa of CD patients was subtractively hybridized. Expression of FN, ED-A, and ED-B in frozen sections from intestinal mucosa was determined by immunohistochemistry. The mRNA expression of the FN isoforms in control, CD, and fibrosis biopsies was quantified by real-time polymerase chain reaction (PCR). Integrin alpha5beta1 protein and mRNA expression was analyzed by fluorescence activated cell sorting (FACS) and PCR, respectively.


RESULTS
Subtractive hybridization indicated differential regulation of FN isoform expression in CD. The immunohistochemical analysis of FN protein revealed a reduction of FN isoforms in inflamed CD mucosa compared to control mucosa. In CD fistulae, the ED-A and ED-B isoforms were virtually absent. In fibrotic mucosa, both proteins were increased. Real-time PCR showed a decrease of FN and ED-A expression during mucosal inflammation in CD in contrast to UC and a significant increase of FN and isoforms in CD fibrosis. No difference was found for protein and mRNA of integrin alpha5beta1 in control, CD, and fibrosis CLPF by FACS and PCR.


CONCLUSIONS
Downregulated expression of migration-inducing FN-isoforms in contrast to unchanged FN receptor expression may contribute to the observed alterations of CD CLPF migration.
Brenmoehl
Julia
J
Department of Internal Medicine I, University of Regensburg, 93042, Regensburg, Germany.
Lang
Markus
M
Hausmann
Martin
M
Leeb
Sandra N
SN
Falk
Werner
W
Schölmerich
Jürgen
J
Göke
Michael
M
Rogler
Gerhard
G
D000328:Adult; D000368:Aged; D017398:Alternative Splicing / Q000235:genetics*; D016022:Case-Control Studies; D003424:Crohn Disease / Q000235:genetics*; D018076:DNA, Complementary; D005260:Female; D005347:Fibroblasts / Q000473:pathology; D005353:Fibronectins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D039081:Integrin alpha5beta1 / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism* / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009693:Nucleic Acid Hybridization; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
D018076:DNA, Complementary; D005353:Fibronectins; D039081:Integrin alpha5beta1; D020033:Protein Isoforms; D012333:RNA, Messenger