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Cytokines regulate proteolysis in major histocompatibility complex class II-dependent antigen presentation by dendritic cells.

Fiebiger E, Meraner P, Weber E, Fang IF, Stingl G, Ploegh H, Maurer D - J. Exp. Med. (2001)

Bottom Line: As a consequence, a wave of MHC class II sodium dodecyl sulfate stable dimer formation ensues in a catS-dependent fashion.In DCs exposed to tetanus toxoid, IL-10 accordingly reduces the number of MHC class II-peptide complexes accessible to tetanus toxoid-specific T cell receptors, as analyzed by measuring T cell receptor downregulation in Ag-specific T cell clones.Thus, the control of protease activity by pro- and antiinflammatory cytokines is an essential feature of the Ag presentation properties of DCs.

View Article: PubMed Central - PubMed

Affiliation: Division of Immunology, Allergy, and Infectious Diseases, Department of Dermatology, University of Vienna Medical School, Austria.

ABSTRACT
Endo/lysosomal proteases control two key events in antigen (Ag) presentation: the degradation of protein Ag and the generation of peptide-receptive major histocompatibility complex (MHC) class II molecules. Here we show that the proinflammatory cytokines tumor necrosis factor alpha and interleukin (IL)-1beta rapidly increase the activity of cathepsin (cat) S and catB in human dendritic cells (DCs). As a consequence, a wave of MHC class II sodium dodecyl sulfate stable dimer formation ensues in a catS-dependent fashion. In contrast, the antiinflammatory cytokine IL-10 renders DCs incapable of upregulating catS and catB activity and in fact, attenuates the level of both enzymes. Suppressed catS and catB activity delays MHC class II sodium dodecyl sulfate stable dimer formation and impairs Ag degradation. In DCs exposed to tetanus toxoid, IL-10 accordingly reduces the number of MHC class II-peptide complexes accessible to tetanus toxoid-specific T cell receptors, as analyzed by measuring T cell receptor downregulation in Ag-specific T cell clones. Thus, the control of protease activity by pro- and antiinflammatory cytokines is an essential feature of the Ag presentation properties of DCs.

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Regulation of cat expression in DCs. (A) cat expression profile of DCs and DC precursors. NP-40 lysates of equal numbers of the indicated cell types were subjected to anti-catS, -catL, -catB, and -catD immunoblotting. Anti-actin and -CD45 reactivity was assessed for control purposes. (B) Regulation of cat expression by pro- and antiinflammatory cytokines. mdDCs were incubated with IL-10 and/or TNF/IL-1 for 24 h before immunoblotting. The positions of pro and mature (m) cats and mol wt markers (kD) are given right and left, respectively.
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Figure 1: Regulation of cat expression in DCs. (A) cat expression profile of DCs and DC precursors. NP-40 lysates of equal numbers of the indicated cell types were subjected to anti-catS, -catL, -catB, and -catD immunoblotting. Anti-actin and -CD45 reactivity was assessed for control purposes. (B) Regulation of cat expression by pro- and antiinflammatory cytokines. mdDCs were incubated with IL-10 and/or TNF/IL-1 for 24 h before immunoblotting. The positions of pro and mature (m) cats and mol wt markers (kD) are given right and left, respectively.

Mentions: Protease activity can be examined by at least two independent methods. First, the level of proteases themselves can be measured by immunochemical methods. However, the assessment of the total protease content based on immunoblotting may not yield an accurate estimate of the level of active enzyme. Therefore, the second approach is to measure the activity of the proteases using active site–directed, mechanism-based inhibitors. Using these two types of approach, we addressed the changes in protease content and activity that accompany the development and the maturation of DCs. First, cat expression in B cells, monocytes, various types of DCs, and DC precursors was assessed by immunoblotting (Fig. 1 A). None of the proteases analyzed (catB, catD, catL, and catS) was detectable as the mature form in resting B cells. The only cat clearly detected in these cells is the proform of catB, also expressed in monocytes. Low level cat expression by resting B cells could have escaped detection by immunoblotting. It is equally possible that resting B cells have to undergo activation and maturation for high level cat expression. Monocytes express pro-catB, pro-catL, pro- and mature catS, as well as pro- and mature catD. During the transition from the monocytic precursor to the immature mdDC, mature catB is expressed de novo and several cats (mature catS, mature catD, and pro-catL) are upregulated. Importantly, the cat expression profile of mdDCs is virtually identical to CD34+ stem cell–derived DCs, and the cat pattern of monocytes, the mdDC precursors, is similar to other well-defined DC progenitors 28; peripheral blood CD11c+ DC (DC1) precursors and CD11c− plasmacytoid DC (DC2) precursors express the proforms of catB and catL as well as mature catS and catD. The levels of mature enzymes detected are low, probably related to the relative immaturity of DC1 and DC2. Thus, resting DCs and DC precursors differ in the expression levels of pro versus mature proteases only. Our data allow the conclusion that, as far as protease content is concerned, mdDCs (referred to as “DC” from now on) can be used as a representative DC population for our studies.


Cytokines regulate proteolysis in major histocompatibility complex class II-dependent antigen presentation by dendritic cells.

Fiebiger E, Meraner P, Weber E, Fang IF, Stingl G, Ploegh H, Maurer D - J. Exp. Med. (2001)

Regulation of cat expression in DCs. (A) cat expression profile of DCs and DC precursors. NP-40 lysates of equal numbers of the indicated cell types were subjected to anti-catS, -catL, -catB, and -catD immunoblotting. Anti-actin and -CD45 reactivity was assessed for control purposes. (B) Regulation of cat expression by pro- and antiinflammatory cytokines. mdDCs were incubated with IL-10 and/or TNF/IL-1 for 24 h before immunoblotting. The positions of pro and mature (m) cats and mol wt markers (kD) are given right and left, respectively.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2193402&req=5

Figure 1: Regulation of cat expression in DCs. (A) cat expression profile of DCs and DC precursors. NP-40 lysates of equal numbers of the indicated cell types were subjected to anti-catS, -catL, -catB, and -catD immunoblotting. Anti-actin and -CD45 reactivity was assessed for control purposes. (B) Regulation of cat expression by pro- and antiinflammatory cytokines. mdDCs were incubated with IL-10 and/or TNF/IL-1 for 24 h before immunoblotting. The positions of pro and mature (m) cats and mol wt markers (kD) are given right and left, respectively.
Mentions: Protease activity can be examined by at least two independent methods. First, the level of proteases themselves can be measured by immunochemical methods. However, the assessment of the total protease content based on immunoblotting may not yield an accurate estimate of the level of active enzyme. Therefore, the second approach is to measure the activity of the proteases using active site–directed, mechanism-based inhibitors. Using these two types of approach, we addressed the changes in protease content and activity that accompany the development and the maturation of DCs. First, cat expression in B cells, monocytes, various types of DCs, and DC precursors was assessed by immunoblotting (Fig. 1 A). None of the proteases analyzed (catB, catD, catL, and catS) was detectable as the mature form in resting B cells. The only cat clearly detected in these cells is the proform of catB, also expressed in monocytes. Low level cat expression by resting B cells could have escaped detection by immunoblotting. It is equally possible that resting B cells have to undergo activation and maturation for high level cat expression. Monocytes express pro-catB, pro-catL, pro- and mature catS, as well as pro- and mature catD. During the transition from the monocytic precursor to the immature mdDC, mature catB is expressed de novo and several cats (mature catS, mature catD, and pro-catL) are upregulated. Importantly, the cat expression profile of mdDCs is virtually identical to CD34+ stem cell–derived DCs, and the cat pattern of monocytes, the mdDC precursors, is similar to other well-defined DC progenitors 28; peripheral blood CD11c+ DC (DC1) precursors and CD11c− plasmacytoid DC (DC2) precursors express the proforms of catB and catL as well as mature catS and catD. The levels of mature enzymes detected are low, probably related to the relative immaturity of DC1 and DC2. Thus, resting DCs and DC precursors differ in the expression levels of pro versus mature proteases only. Our data allow the conclusion that, as far as protease content is concerned, mdDCs (referred to as “DC” from now on) can be used as a representative DC population for our studies.

Bottom Line: As a consequence, a wave of MHC class II sodium dodecyl sulfate stable dimer formation ensues in a catS-dependent fashion.In DCs exposed to tetanus toxoid, IL-10 accordingly reduces the number of MHC class II-peptide complexes accessible to tetanus toxoid-specific T cell receptors, as analyzed by measuring T cell receptor downregulation in Ag-specific T cell clones.Thus, the control of protease activity by pro- and antiinflammatory cytokines is an essential feature of the Ag presentation properties of DCs.

View Article: PubMed Central - PubMed

Affiliation: Division of Immunology, Allergy, and Infectious Diseases, Department of Dermatology, University of Vienna Medical School, Austria.

ABSTRACT
Endo/lysosomal proteases control two key events in antigen (Ag) presentation: the degradation of protein Ag and the generation of peptide-receptive major histocompatibility complex (MHC) class II molecules. Here we show that the proinflammatory cytokines tumor necrosis factor alpha and interleukin (IL)-1beta rapidly increase the activity of cathepsin (cat) S and catB in human dendritic cells (DCs). As a consequence, a wave of MHC class II sodium dodecyl sulfate stable dimer formation ensues in a catS-dependent fashion. In contrast, the antiinflammatory cytokine IL-10 renders DCs incapable of upregulating catS and catB activity and in fact, attenuates the level of both enzymes. Suppressed catS and catB activity delays MHC class II sodium dodecyl sulfate stable dimer formation and impairs Ag degradation. In DCs exposed to tetanus toxoid, IL-10 accordingly reduces the number of MHC class II-peptide complexes accessible to tetanus toxoid-specific T cell receptors, as analyzed by measuring T cell receptor downregulation in Ag-specific T cell clones. Thus, the control of protease activity by pro- and antiinflammatory cytokines is an essential feature of the Ag presentation properties of DCs.

Show MeSH
Related in: MedlinePlus