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.

1.
Demartino GN, Gillette TG: Proteasomes: machines for all reasons. Cell 2007;129:659–662.
2.
Segref A, Hoppe T: Think locally: control of ubiquitin-dependent protein degradation in neurons. EMBO Rep 2009;10:44–50.
3.
Hochstrasser M: Origin and function of ubiquitin-like proteins. Nature 2009;458:422–429.
4.
Hirsch C, Gauss R, Horn SC, Neuber O, Sommer T: The ubiquitylation machinery of the endoplasmic reticulum. Nature 2009;458:453–460.
5.
Murata S, Yashiroda H, Tanaka K: Molecular mechanisms of proteasome assembly. Nat Rev Mol Cell Biol 2009;10:104–115.
6.
Kruger E, Kuckelkorn U, Sijts A, Kloetzel PM: The components of the proteasome system and their role in MHC class I antigen processing. Rev Physiol Biochem Pharmacol 2003;148:81–104.
7.
Jung T, Catalgol B, Grune T: The proteasomal system. Mol Aspects Med 2009;30:191–296.
8.
Tu L, Moriya C, Imai T, Ishida H, Tetsutani K, Duan X, Murata S, Tanaka K, Shimokawa C, Hisaeda H, Himeno K: Critical role for the immunoproteasome subunit LMP7 in the resistance of mice to Toxoplasma gondii infection. Eur J Immunol 2009;39:3385–3394.
9.
Barton LF, Cruz M, Rangwala R, Deepe GS Jr, Monaco JJ: Regulation of immunoproteasome subunit expression in vivo following pathogenic fungal infection. J Immunol 2002;169:3046–3052.
10.
Groettrup M, Khan S, Schwarz K, Schmidtke G: Interferon-γ inducible exchanges of 20S proteasome active site subunits: why? Biochimie 2001;83:367–372.
11.
Frisan T, Levitsky V, Polack A, Masucci MG: Phenotype-dependent differences in proteasome subunit composition and cleavage specificity in B cell lines. J Immunol 1998;160:3281–3289.
12.
Hallermalm K, Seki K, Wei C, Castelli C, Rivoltini L, Kiessling R, Levitskaya J: Tumor necrosis factor-α induces coordinated changes in major histocompatibility class I presentation pathway, resulting in increased stability of class I complexes at the cell surface. Blood 2001;98:1108–1115.
[PubMed]
13.
Stohwasser R, Kuckelkorn U, Kraft R, Kostka S, Kloetzel PM: 20S proteasome from LMP7 knock out mice reveals altered proteolytic activities and cleavage site preferences. FEBS Lett 1996;383:109–113.
14.
Basler M, Moebius J, Elenich L, Groettrup M, Monaco JJ: An altered T cell repertoire in MECL-1-deficient mice. J Immunol 2006;176:6665–6672.
15.
Caudill CM, Jayarapu K, Elenich L, Monaco JJ, Colbert RA, Griffin TA: T cells lacking immunoproteasome subunits MECL-1 and LMP7 hyperproliferate in response to polyclonal mitogens. J Immunol 2006;176:4075–4082.
16.
Yu X, Kem DC: Proteasome inhibition during myocardial infarction. Cardiovasc Res 2010;85:312–320.
17.
Testa U: Proteasome inhibitors in cancer therapy. Curr Drug Targets 2009;10:968–981.
18.
Koreth J, Alyea EP, Murphy WJ, Welniak LA: Proteasome inhibition and allogeneic hematopoietic stem cell transplantation: a review. Biol Blood Marrow Transplant 2009;15:1502–1512.
19.
Everly JJ, Walsh RC, Alloway RR, Woodle ES: Proteasome inhibition for antibody-mediated rejection. Curr Opin Organ Transplant 2009;14:662–666.
20.
Zavrski I, Kleeberg L, Kaiser M, Fleissner C, Heider U, Sterz J, Jakob C, Sezer O: Proteasome as an emerging therapeutic target in cancer. Curr Pharm Des 2007;13:471–485.
21.
Letoha T, Feher LZ, Pecze L, Somlai C, Varga I, Kaszaki J, Toth G, Vizler C, Tiszlavicz L, Takacs T: Therapeutic proteasome inhibition in experimental acute pancreatitis. World J Gastroenterol 2007;13:4452–4457.
22.
Rogler G, Hausmann M, Vogl D, Aschenbrenner E, Andus T, Falk W, Andreesen R, Scholmerich J, Gross V: Isolation and phenotypic characterization of colonic macrophages. Clin Exp Immunol 1998;112:205–215.
[PubMed]
23.
Salomons FA, Acs K, Dantuma NP: Illuminating the ubiquitin/proteasome system. Exp Cell Res 2010;316:1289–1295.
24.
Sorokin AV, Kim ER, Ovchinnikov LP: Proteasome system of protein degradation and processing. Biochemistry (Mosc) 2009;74:1411–1442.
25.
Navon A, Ciechanover A: The 26 S proteasome: from basic mechanisms to drug targeting. J Biol Chem 2009;284:33713–33718.
26.
Loureiro J, Ploegh HL: Antigen presentation and the ubiquitin-proteasome system in host-pathogen interactions. Adv Immunol 2006;92:225–305.
27.
Makala LH, Nishikawa Y, Suzuki N, Nagasawa H: Immunology. Antigen-presenting cells in the gut. J Biomed Sci 2004;11:130–141.
28.
Pavli P, Maxwell L, Van de Pol E, Doe F: Distribution of human colonic dendritic cells and macrophages. Clin Exp Immunol 1996;104:124–132.
29.
Smythies LE, Sellers M, Clements RH, Mosteller-Barnum M, Meng G, Benjamin WH, Orenstein JM, Smith PD: Human intestinal macrophages display profound inflammatory anergy despite avid phagocytic and bacteriocidal activity. J Clin Invest 2005;115:66–75.
[PubMed]
30.
Carlsen HS, Yamanaka T, Scott H, Rugtveit J, Brandtzaeg P: The proportion of CD40+ mucosal macrophages is increased in inflammatory bowel disease whereas CD40 ligand (CD154)+ T cells are relatively decreased, suggesting differential modulation of these costimulatory molecules in human gut lamina propria. Inflamm Bowel Dis 2006;12:1013–1024.
[PubMed]
31.
Spottl T, Hausmann M, Kreutz M, Peuker A, Vogl D, Scholmerich J, Falk W, Andreesen R, Andus T, Herfarth H, Rogler G: Monocyte differentiation in intestine-like macrophage phenotype induced by epithelial cells. J Leukoc Biol 2001;70:241–251.
32.
Rugtveit J, Bakka A, Brandtzaeg P: Differential distribution of B7.1 (CD80) and B7.2 (CD86) costimulatory molecules on mucosal macrophage subsets in human inflammatory bowel disease (IBD). Clin Exp Immunol 1997;110:104–113.
[PubMed]
33.
Rogler G, Hausmann M, Spottl T, Vogl D, Aschenbrenner E, Andus T, Falk W, Scholmerich J, Gross V: T-cell co-stimulatory molecules are upregulated on intestinal macrophages from inflammatory bowel disease mucosa. Eur J Gastroenterol Hepatol 1999;11:1105–1111.
34.
Visekruna A, Joeris T, Seidel D, Kroesen A, Loddenkemper C, Zeitz M, Kaufmann SH, Schmidt-Ullrich R, Steinhoff U: Proteasome-mediated degradation of IĸBα and processing of p105 in Crohn disease and ulcerative colitis. J Clin Invest 2006;116:3195–3203.
35.
Rogler G, Brand K, Vogl D, Page S, Hofmeister R, Andus T, Knuechel R, Baeuerle PA, Scholmerich J, Gross V: Nuclear factor ĸB is activated in macrophages and epithelial cells of inflamed intestinal mucosa. Gastroenterology 1998;115:357–369.
[PubMed]
36.
Kosovac K, Brenmoehl J, Holler E, Falk W, Schoelmerich J, Hausmann M, Rogler G: Association of the NOD2 genotype with bacterial translocation via altered cell-cell contacts in Crohn’s disease patients. Inflamm Bowel Dis 2010.
37.
Colpaert S, Vastraelen K, Liu Z, Maerten P, Shen C, Penninckx F, Geboes K, Rutgeerts P, Ceuppens JL: In vitro analysis of interferon gamma (IFN-γ) and interleukin-12 (IL-12) production and their effects in ileal Crohn’s disease. Eur Cytokine Netw 2002;13:431–437.
38.
Sasaki T, Hiwatashi N, Yamazaki H, Noguchi M, Toyota T: The role of interferon γ in the pathogenesis of Crohn’s disease. Gastroenterol Jpn 1992;27:29–36.
39.
Guarner F: What is the role of the enteric commensal flora in IBD? Inflamm Bowel Dis 2008;14(suppl 2):S83–S84.
40.
Murphy SJ, Ullman TA, Abreu MT: Gut microbes in Crohn’s disease: getting to know you better? Am J Gastroenterol 2008;103:397–398.
41.
Conte MP, Schippa S, Zamboni I, Penta M, Chiarini F, Seganti L, Osborn J, Falconieri P, Borrelli O, Cucchiara S: Gut-associated bacterial microbiota in paediatric patients with inflammatory bowel disease. Gut 2006;55:1760–1767.
[PubMed]
42.
Tien MT, Girardin SE, Regnault B, Le Bourhis L, Dillies MA, Coppee JY, Bourdet-Sicard R, Sansonetti PJ, Pedron T: Anti-inflammatory effect of Lactobacillus casei on Shigella-infected human intestinal epithelial cells. J Immunol 2006;176:1228–1237.
43.
Bentz S, Hausmann M, Piberger H, Kellermeier S, Paul S, Held L, Falk W, Obermeier F, Fried M, Scholmerich J, Rogler G: Clinical relevance of IgG antibodies against food antigens in Crohn’s disease: a double-blind cross-over diet intervention study. Digestion 2010;81:252–264.
[PubMed]
44.
Duchmann R, Kaiser I, Hermann E, Mayet W, Ewe K, Meyer zum Buschenfelde KH: Tolerance exists towards resident intestinal flora but is broken in active inflammatory bowel disease (IBD). Clin Exp Immunol 1995;102:448–455.
[PubMed]
45.
Duchmann R, Schmitt E, Knolle P, Meyer zum Buschenfelde KH, Neurath M: Tolerance towards resident intestinal flora in mice is abrogated in experimental colitis and restored by treatment with interleukin-10 or antibodies to interleukin-12. Eur J Immunol 1996;26:934–938.
[PubMed]
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