Header

UZH-Logo

Maintenance Infos

Downregulation of the ubiquitin-proteasome system in normal colonic macrophages and reinduction in inflammatory bowel disease


Hetzenecker, A M; Seidl, M C; Kosovac, K; Herfarth, H; Kellermeier, S; Obermeier, F; Falk, W; Schoelmerich, J; Hausmann, M; Rogler, G (2012). Downregulation of the ubiquitin-proteasome system in normal colonic macrophages and reinduction in inflammatory bowel disease. Digestion, 86(1):34-47.

Abstract

BACKGROUND: In normal mucosa, intestinal lamina propria macrophages (IMACs) maintain tolerance against food antigens and the commensal bacterial flora. Several mechanisms have been identified that mediate tolerance. The ubiquitin-proteasome system (UPS) is a large multiprotein complex that degrades cellular proteins. As the UPS may modulate immune functions of IMACs, we performed a detailed investigation of UPS expression and function under normal conditions and in cells derived from patients suffering from inflammatory bowel disease (IBD).
METHODS: IMACs were isolated from intestinal mucosa. mRNA expression of macrophages differentiated in vitro (i.v. MACs) and IMACs was compared by Affymetrix® oligonucleotide arrays. Quantitative Taqman-PCR was performed on five exemplary proteasomal and five ubiquitinylation genes each. Proteins were analyzed by immunohistochemistry and Western blotting. Proteasome function was assessed by a fluorimetric test.
RESULTS: Affymetrix analysis showed downregulation of mRNA expression of almost all represented proteasomal and of 22 ubiquitination-associated genes in IMACs as compared to i.v. MACs and monocytes. By quantitative PCR, up to tenfold higher mRNA expression of 10 exemplary genes of the UPS (UBE2A, UBE2D2, UBE2L6, USP14, UBB and ATPase2, β2, β5, β2i/MECL-1, β5i/LMP7) was demonstrated in i.v. MACs as compared to IMACs. Immunohistochemistry and Western blots confirmed these findings in intestinal mucosa of controls and patients suffering from diverticulitis. In contrast, a significant increase in protein amounts was found in mucosa of patients with IBD.
CONCLUSION: Reduced expression of subunits of the UPS in IMACs of normal mucosa supports the concept of the presence of a nonreactive, anergic macrophage phenotype in the gut under normal conditions. Reinduction in IMACs of IBD mucosa reflects activated IMACs which can present antigenic peptides and thus support inflammation.

Abstract

BACKGROUND: In normal mucosa, intestinal lamina propria macrophages (IMACs) maintain tolerance against food antigens and the commensal bacterial flora. Several mechanisms have been identified that mediate tolerance. The ubiquitin-proteasome system (UPS) is a large multiprotein complex that degrades cellular proteins. As the UPS may modulate immune functions of IMACs, we performed a detailed investigation of UPS expression and function under normal conditions and in cells derived from patients suffering from inflammatory bowel disease (IBD).
METHODS: IMACs were isolated from intestinal mucosa. mRNA expression of macrophages differentiated in vitro (i.v. MACs) and IMACs was compared by Affymetrix® oligonucleotide arrays. Quantitative Taqman-PCR was performed on five exemplary proteasomal and five ubiquitinylation genes each. Proteins were analyzed by immunohistochemistry and Western blotting. Proteasome function was assessed by a fluorimetric test.
RESULTS: Affymetrix analysis showed downregulation of mRNA expression of almost all represented proteasomal and of 22 ubiquitination-associated genes in IMACs as compared to i.v. MACs and monocytes. By quantitative PCR, up to tenfold higher mRNA expression of 10 exemplary genes of the UPS (UBE2A, UBE2D2, UBE2L6, USP14, UBB and ATPase2, β2, β5, β2i/MECL-1, β5i/LMP7) was demonstrated in i.v. MACs as compared to IMACs. Immunohistochemistry and Western blots confirmed these findings in intestinal mucosa of controls and patients suffering from diverticulitis. In contrast, a significant increase in protein amounts was found in mucosa of patients with IBD.
CONCLUSION: Reduced expression of subunits of the UPS in IMACs of normal mucosa supports the concept of the presence of a nonreactive, anergic macrophage phenotype in the gut under normal conditions. Reinduction in IMACs of IBD mucosa reflects activated IMACs which can present antigenic peptides and thus support inflammation.

Statistics

Citations

7 citations in Web of Science®
9 citations in Scopus®
Google Scholar™

Altmetrics

Downloads

49 downloads since deposited on 13 Mar 2013
12 downloads since 12 months
Detailed statistics

Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Clinic for Gastroenterology and Hepatology
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:2012
Deposited On:13 Mar 2013 14:11
Last Modified:16 Jun 2016 14:54
Publisher:Karger
ISSN:0012-2823
Publisher DOI:https://doi.org/10.1159/000336353
PubMed ID:22710419

Download

Preview Icon on Download
Preview
Content: Accepted Version
Filetype: PDF
Size: 17kB
View at publisher
Preview Icon on Download
Preview
Content: Published Version
Filetype: PDF
Size: 1MB

TrendTerms

TrendTerms displays relevant terms of the abstract of this publication and related documents on a map. The terms and their relations were extracted from ZORA using word statistics. Their timelines are taken from ZORA as well. The bubble size of a term is proportional to the number of documents where the term occurs. Red, orange, yellow and green colors are used for terms that occur in the current document; red indicates high interlinkedness of a term with other terms, orange, yellow and green decreasing interlinkedness. Blue is used for terms that have a relation with the terms in this document, but occur in other documents.
You can navigate and zoom the map. Mouse-hovering a term displays its timeline, clicking it yields the associated documents.

Author Collaborations