Cathepsin D is up-regulated in inflammatory bowel disease macrophages.
Down-regulation of receptors involved in the recognition or transmission of inflammatory signals and a reduced responsiveness support the concept that macrophages are 'desensitized' during their differentiation in the intestinal mucosa. During inflammatory bowel disease (IBD) intestinal macrophages (IMACs) change to a reactive or 'aggressive' type. After having established a method of isolation and purification of IMACs, message for cathepsin D was one of the mRNAs we found to be up-regulated in a subtractive hybridization of Crohn's disease (CD) macrophages versus IMACs from control mucosa. The expression of cathepsin D in intestinal mucosa was analysed by immunohistochemistry in biopsies from IBD and control patients and in a mouse model of dextran sulphate sodium (DSS)-induced acute and chronic colitis. IMACs were isolated and purified from normal and inflamed mucosa by immunomagnetic beads armed with a CD33 antibody. RT-PCR was performed for cathepsin D mRNA. Results were confirmed by Northern blot and flow cytometrical analysis. Immunohistochemistry revealed a significant increase in the cathepsin D protein expression in inflamed intestinal mucosa from IBD patients compared to non-inflamed mucosa. No cathepsin D polymerase chain reaction (PCR) product could be obtained with mRNA from CD33-positive IMACs from normal mucosa. Reverse transcription (RT)-PCR showed an induction of mRNA for cathepsin D in purified IMACs from IBD patients. Northern blot and flow cytometry analysis confirmed these results. Cathepsin D protein was also found in intestinal mucosa in acute and chronic DSS-colitis but was absent in normal mucosa. This study shows that expression of cathepsin D is induced in inflammation-associated IMACs. The presence of cathepsin D might contribute to the mucosal damage in IBD.
Hausmann
M
M
Department of Internal Medicine I, University of Regensburg, Regensburg, Germany. martin.hausmann@klinik.uni-regensburg.de
Obermeier
F
F
Schreiter
K
K
Spottl
T
T
Falk
W
W
Schölmerich
J
J
Herfarth
H
H
Saftig
P
P
Rogler
G
G
D000208:Acute Disease; D000818:Animals; D002402:Cathepsin D / Q000235:genetics / Q000378:metabolism*; D002908:Chronic Disease; D016264:Dextran Sulfate; D005260:Female; D007124:Immunoenzyme Techniques; D015212:Inflammatory Bowel Diseases / Q000139:chemically induced / Q000201:enzymology*; D007413:Intestinal Mucosa / Q000201:enzymology; D008264:Macrophages / Q000201:enzymology*; D051379:Mice; D008807:Mice, Inbred BALB C; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation
D012333:RNA, Messenger; D016264:Dextran Sulfate; D002402:Cathepsin D