Selective binding of bacterial toxins to major histocompatibility complex class II-expressing cells is controlled by invariant chain and HLA-DM

Lavoie, Pascal M.; Thibodeau, Jacques; Cloutier, Isabelle; Busch, Robert; Sékaly, R P

doi:10.1073/pnas.94.13.6892

Cited by 38 publications

(39 citation statements)

References 29 publications

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“…This difference might be due to the fact that SEA has the ability to engage either chain of the class II MHC complex and could thus have more binding sites than SEB, which can bind to only the ␤-chain of class II MHC complexes. In addition, SEA and SEB binding are differentially sensitive to structural heterogeneity in MHC class II-associated cofactors, as a consequence of the differential regulation of expression of Ag-processing cofactors, including CD74 and HLA-DM, on different APCs (56,57).…”

Section: Discussionmentioning

confidence: 99%

Monocyte Chemoattractant Protein-1 Production by Intestinal Myofibroblasts in Response to Staphylococcal Enterotoxin A: Relevance to Staphylococcal Enterotoxigenic Disease

Pinchuk¹,

Beswick²,

Saada³

et al. 2007

The Journal of Immunology

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Food poisoning due to staphylococcal enterotoxins A and B (SEA and SEB) affects hundreds of thousands of people annually. SEA and SEB induce massive intestinal cytokine production, which is believed to be the key factor in staphylococcal enterotoxin enteropathy. MHC class II molecules are the major receptors for staphylococcal enterotoxins. We recently demonstrated that normal human subepithelial intestinal myofibroblasts (IMFs) express MHC class II molecules. We hypothesized that IMFs are among the first cells to respond to staphylococcal enterotoxins and contribute to the cytokine production associated with staphylococcal enterotoxin pathogenesis. We demonstrated here that primary cultured IMFs bind staphylococcal enterotoxins in a MHC class II-dependent fashion in vitro. We also demonstrated that staphylococcal enterotoxins can cross a CaCo-2 epithelial monolayer in coculture with IMFs and bind to the MHC class II on IMFs. IMFs responded to SEA, but not SEB, exposure with 3- to 20-fold increases in the production of proinflammatory chemokines (MCP-1, IL-8), cytokines (IL-6), and growth factors (GM-CSF and G-CSF). The SEA induction of the proinflammatory mediators by IMFs resulted from the efficient cross-linking of MHC class II molecules because cross-linking of class II MHC by biotinylated anti-HLA-DR Abs induced similar cytokine patterns. The studies presented here show that MCP-1 is central to the production of other cytokines elicited by SEA in IMFs because its neutralization with specific Abs prevented the expression of IL-6 and IL-8 by IMFs. Thus, MCP-1 may play a leading role in initiation of inflammatory injury associated with staphylococcal enterotoxigenic disease.

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Section: Discussionmentioning

confidence: 99%

Monocyte Chemoattractant Protein-1 Production by Intestinal Myofibroblasts in Response to Staphylococcal Enterotoxin A: Relevance to Staphylococcal Enterotoxigenic Disease

Pinchuk¹,

Beswick²,

Saada³

et al. 2007

The Journal of Immunology

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“…Cells (1.2 ϫ 10 7 ) were trypsinized, washed in PBS and lysed into Triton X-100 1% as described previously (58). After centrifugation, supernatants were harvested and incubated with 20 l (50% beads) of CL-6B Sepharose (Amersham Pharmacia Biotech) for 1 h at 4°C with agitation.…”

Section: Immunoprecipitations and Western Blottingmentioning

confidence: 99%

Functional Characterization of a Lysosomal Sorting Motif in the Cytoplasmic Tail of HLA-DOβ

Brunet¹,

Samaan²,

Deshaies³

et al. 2000

Journal of Biological Chemistry

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HLA-DO is an intracellular non-classical class II major histocompatibility complex molecule expressed in the endocytic pathway of B lymphocytes, which regulates the loading of antigenic peptides onto classical class II molecules such as HLA-DR. The activity of HLA-DO is mediated through its interaction with the peptide editor HLA-DM. Here, our results demonstrate that although HLA-DO is absolutely dependent on its association with DM to egress the endoplasmic reticulum, the cytoplasmic portion of its ␤ chain encodes a functional lysosomal sorting signal. By confocal microscopy and flow cytometry analysis, we show that reporter transmembrane molecules fused to the cytoplasmic tail of HLA-DO␤ accumulated in Lamp-1 ؉ vesicles of transfected HeLa cells. Mutagenesis of a leucine-leucine motif abrogated lysosomal accumulation and resulted in cell surface redistribution of reporter molecules. Finally, we show that mutation of the di-leucine sequence in DO␤ did not alter its lysosomal sorting when associated with DM molecules. Taken together, these results demonstrate that lysosomal expression of the DO-DM complex is mediated primarily by the tyrosine-based motif of HLA-DM and suggest that the DO␤-encoded motif is involved in the fine-tuning of the intracellular sorting. Major histocompatibility complex (MHC)1 class II molecules are heterodimeric cell surface glycoproteins that present antigens to CD4 ϩ T cells (1). The antigenic peptide-class II complexes are expressed on specialized antigen-presenting cells such as macrophages and B lymphocytes. Following their synthesis, the ␣ and ␤ subunits of the class II molecule associate in the endoplasmic reticulum (ER) together with the invariant chain (Ii) (2). The latter folds in part through the groove of the class II molecule, stabilizing the ␣␤ heterodimer and preventing the undesirable binding of ER polypeptides (3-6). Studies using mice with inactivated Ii genes suggested that Ii is necessary for efficient exit of newly synthesized class II molecules from the ER (7, 8). However, it was later demonstrated that high levels of class II molecules reach the surface of Ii Ϫ dendritic cells (9). Moreover, transfected cells express a substantial amount of class II molecules at their plasma membrane even in the absence of Ii (10). Such a phenotype probably results from the binding of endogenous peptides or polypeptides present in the ER (6, 11) and supports the notion that occupancy of the peptide-binding groove is sufficient to allow ER egress (12).Another function of Ii is to direct efficiently MHC class II molecules to the endocytic antigen-loading compartments (13-15). Two short leucine-based sequences located in the cytoplasmic tail of Ii are responsible for trafficking through the endocytic pathway (16,17). Similar motifs in many proteins are specifically recognized at the cell surface and trans-Golgi by elements of the sorting machinery (reviewed in Ref. 18).Once the class II-Ii complex reaches the endosomal compartments, the invariant chain is progressively degraded by v...

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“…As such, they should bind to the totality of cell surface MHC class II molecules and thus engage the TCR with a higher avidity than nominal Ags. However, we and others have shown that SAg binding and presentation is markedly affected by the structural microheterogeneity of the MHC class II molecules, probably imparted by the groove-occupying peptide (11)(12)(13)(14)(15)(16). Whether that phenomenon modulates the activity of SAgs on T cells has not been addressed in previous studies.…”

mentioning

confidence: 86%

“…The concentration of each batch of purified SEA or L243-Fab was carefully determined on Coomassie-stained SDS-PAGE and by Bradford protein dosage (data not shown). The radiolabeling and fractionation of SEA or L243 was performed as described (12). SDS-PAGE separation of the labeled fraction confirmed that the ligand of interest was responsible for Ͼ95% of the total specific activity.…”

Section: Surface Binding Experiments and Scatchard Analysesmentioning

confidence: 99%

“…After 1 h at 4°C, 1 ml of PBS was added, and the beads were centrifuged for 10 s. The beads were again washed 10 times (lysis buffer with 0.5% Triton X-100) and resuspended in 50 l of 2ϫ Laemmli proteinloading buffer. The samples were boiled for 5 min, loaded on 10% SDS-PAGE, and analyzed by Western blotting using the XD5.117 and/or DA6.147 Abs as previously described (12). A peroxydase-coupled goat anti-mouse secondary Ab reactive to the Fc portion of mouse Igs was used for chemiluminescence detection (Pierce).…”

Section: Quantitative Immunoprecipitations and Western Blottingmentioning

confidence: 99%

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Quantitative Relationship Between MHC Class II-Superantigen Complexes and the Balance of T Cell Activation Versus Death

Lavoie

McGrath

Shoukry

et al. 2001

The Journal of Immunology

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The binding of bacterial superantigens (SAgs) is profoundly affected by the nature of the MHC class II-associated antigenic peptide. It was proposed that this limitation in the density of SAgs displayed at the surface of APCs is important for efficient TCR serial triggering as well as for preventing apoptosis of the responding T lymphocytes. Here, we have addressed quantitatively the size of this SAg-receptive pool of HLA-DR molecules that are available to bind and present staphylococcal enterotoxin A (SEA) at the surface of B lymphocytes. Our binding curves, depletion experiments, and quantitative immunoprecipitations show that about half the HLA-DR class II molecules on B cells are refractory to SEA binding. Yet, as compared with typical nominal Ags, an unusually high amount of class II-SAg complexes can be presented to T cells. This characteristic appears to be necessary for SAg-induced T cell apoptosis. When <0.3% of the total cell surface MHC class II molecules are occupied by SEA, T cells undergo a normal sequence of early activation events. However, presentation of a ligand density beyond this threshold results in T cell activation that is readily aborted by apoptosis but only after a few cell divisions. Thus, we confirm the existence of MHC class II subsets that are structurally unable to present SEA and provide a quantitative framework to account for the ability of bacterial SAgs to induce peripheral activation vs tolerance in the host.

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Selective binding of bacterial toxins to major histocompatibility complex class II-expressing cells is controlled by invariant chain and HLA-DM

Cited by 38 publications

References 29 publications

Monocyte Chemoattractant Protein-1 Production by Intestinal Myofibroblasts in Response to Staphylococcal Enterotoxin A: Relevance to Staphylococcal Enterotoxigenic Disease

Monocyte Chemoattractant Protein-1 Production by Intestinal Myofibroblasts in Response to Staphylococcal Enterotoxin A: Relevance to Staphylococcal Enterotoxigenic Disease

Functional Characterization of a Lysosomal Sorting Motif in the Cytoplasmic Tail of HLA-DOβ

Quantitative Relationship Between MHC Class II-Superantigen Complexes and the Balance of T Cell Activation Versus Death

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