Activation of Type B T Cells after Protein Immunization Reveals Novel Pathways of In Vivo Presentation of Peptides

Lovitch, Scott B.; Esparza, Thomas J.; Schweitzer, George G.; Herzog, Jeremy; Unanue, Emil R.

doi:10.4049/jimmunol.178.1.122

Cited by 24 publications

(24 citation statements)

References 35 publications

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“…Although peptides are small fragments of proteins, they can be presented quite differently, especially when loaded directly into empty surface class II molecules (19). Moreover, because many peptide vaccines are in clinical trials or have been approved for clinical applications (20,21), it is important to understand how exogenous peptides are loaded and presented.…”

Section: Discussionmentioning

confidence: 99%

Comparing Pooled Peptides with Intact Protein for Accessing Cross-presentation Pathways for Protective CD8+ and CD4+ T Cells

Zhang

Hong

et al. 2009

Journal of Biological Chemistry

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To better understand the mechanisms of intracellular trafficking and presentation of exogenous peptides by antigen-presenting cells (APC), we compared the handling of overlapping 24-mer peptides from HIV Nef either mixed or covalently linked in tandem in one protein. Once internalized, peptides trafficked not only to endosomes but also to cytosol, and activated CD8 ؉ and CD4؉ T cells. In contrast, whole protein was found to traffic only to the endosomal compartments, and primarily activated CD4 ؉ T cells. Finally, with adjuvant, overlapping peptides were capable of protecting against lethal viral challenge, whereas the intact protein was less protective. These data suggest that overlapping long peptides are cross-presented through more varied intracellular routes and are more efficient in priming protective immunity than the whole protein.Despite much progress in vaccine development, there are still several challenges for design of subunit vaccines. Against intracellular pathogens, it is especially important to immunize protective CD4 ϩ and CD8 ϩ T cell responses. The former recognize epitopes presented by major histocompatibility complex (MHC) 3 class II molecules that are normally loaded mainly with peptides derived from exogenous antigens. Natural processing and loading are catalyzed by HLA-or H2-DM in acidic lysosomes (1).By contrast, CD8 ϩ T cell responses typically depend on epitope loading via the class I pathway. This "endogenous" route starts from the cytosol of any cells naturally infected by the relevant virus, which may not include professional antigen presenting cells (pAPCs). Once processed by cytosolic proteases, viral peptide fragments are transported into the endoplasmic reticulum, and loaded onto MHC class I molecules, which then traffic to the surface where they can present to CD8 ϩ T cells (2, 3). For exogenous antigens, "cross-presentation" by pAPCs is essential for priming CD8 ϩ as well as CD4 ϩ T cells.Although they must be crucial for most CD8 ϩ T cell vaccination strategies, the mechanisms underlying cross-presentation are not understood. First, internalized antigens are known to enter the cytoplasm, although the mechanisms remain unknown. Once in the cytoplasm, they can follow the conventional MHC class I pathway, i.e. processing by cytosolic proteasomes or proteases, transport into the endoplasmic reticulum, loading onto MHC class I molecules, and then trafficking to the surface for recognition by T cells (2, 3). Second, antigens internalized into endocytic compartments could be degraded by the local proteases into peptides and then loaded onto MHC class I molecules in the endocytic compartments that are recycled to and from the cell surface (4). Third, endosomes may fuse with the endoplasmic reticulum, allowing direct access of such peptides for loading onto nascent MHC class I molecules there before presentation at the cell surface (5); however, this theory remains controversial (6, 7).It has been hypothesized that endocytic and cytosolic proteases process antigens differently. If ...

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Section: Discussionmentioning

confidence: 99%

Comparing Pooled Peptides with Intact Protein for Accessing Cross-presentation Pathways for Protective CD8+ and CD4+ T Cells

Zhang

Hong

et al. 2009

Journal of Biological Chemistry

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“…A particularly dramatic example of alternate peptide conformations comes from the work of Unanue and coworkers (21,25). They provide evidence that a single peptide, apparently bound in a fixed register, can have at least two conformations distinguished by different sets of T cells, depending on whether the peptide was loaded extracellularly (conformation A) or via the usual endocytic pathway (conformation B).…”

Section: Discussionmentioning

confidence: 99%

Specificity and detection of insulin-reactive CD4⁺T cells in type 1 diabetes in the nonobese diabetic (NOD) mouse

Crawford

Stadinski

Jin

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

136

212

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In the nonobese diabetic (NOD) mouse model of type 1 diabetes (T1D), an insulin peptide (B:9-23) is a major target for pathogenic CD4 + T cells. However, there is no consensus on the relative importance of the various positions or "registers" this peptide can take when bound in the groove of the NOD MHCII molecule, IA g7 . This has hindered structural studies and the tracking of the relevant T cells in vivo with fluorescent peptide-MHCII tetramers. Using mutated B:9-23 peptides and methods for trapping the peptide in particular registers, we show that most, if not all, NOD CD4 + T cells react to B:9-23 bound in low-affinity register 3. However, these T cells can be divided into two types depending on whether their response is improved or inhibited by substituting a glycine for the B:21 glutamic acid at the p8 position of the peptide. On the basis of these findings, we constructed a set of fluorescent insulin-IA g7 tetramers that bind to most insulin-specific Tcell clones tested. A mixture of these tetramers detected a high frequency of B:9-23-reactive CD4 + T cells in the pancreases of prediabetic NOD mice. Our data are consistent with the idea that, within the pancreas, unique processing of insulin generates truncated peptides that lack or contain the B:21 glutamic acid. In the thymus, the absence of this type of processing combined with the low affinity of B:9-23 binding to IA g7 in register 3 may explain the escape of insulin-specific CD4 + T cells from the mechanisms that usually eliminate self-reactive T cells.antigen processing | autoimmunity | T cell receptor | self tolerance I n human type 1 diabetes (T1D) and in the nonobese diabetic (NOD) mouse model of the disease, insulin is a major autoantigen for both B cells and T cells (reviewed in refs. 1, 2). A peptide from the insulin beta chain (B:9-23) has been known for many years to be the major target of insulin-reactive CD4 + T cells in NOD T1D . However, the data suggest that this peptide can bind to the NOD class II major histocompatibility (MHCII), IA g7 , in multiple positions or "registers" within the peptide binding groove (3-7). These registers are defined by the peptide amino acids occupying positions p1-p9 in the groove, which include the "anchor" amino acids at p1, p4, p6, and p9, whose side chains interact with compatible pockets in the MHC groove (8, 9). For an individual peptide, each shift in register puts a new set of peptide amino acids into these anchor positions and brings a different set of peptide amino acid side chains to the surface for potential T-cell recognition, generating a unique ligand. Defining which of the possible B:9-23 binding register(s) in the IA g7 groove create the ligand(s) for diabetogenic insulin-reactive T cells has been difficult, leading to uncertainty in exactly how this peptide is processed and presented to T cells in the pancreas and the inability to construct the relevant fluorescent insulin-IA g7 multimers for in vivo tracking the autoimmune B:9-23-specific T cells.Recently, using techniques to trap versio...

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“…In support of this idea, we found that some of the peptides presented by DC under physiological conditions were susceptible to DM-mediated exchange, suggesting that they were generated through a processing pathway that did not include substantial exposure to DM (107,109,110). Although most peptides tested were relatively resistant to DM action, with DM resistance factors similar to or even greater than a high-affinity immunodominant viral epitope, several peptides were highly sensitive to DM action, with susceptibility values near that of CLIP, the canonical DM-susceptible fragment of the MHC II associated invariant chain removed by DM.…”

Section: Peptide Sourcementioning

confidence: 59%

“…Indeed, the eluted peptide with the highest ⌬IC 50 values among those tested (EAFQAMPPEELNK, ⌬IC 50 ϭ 0.160 M) derived from transforming growth factor-␤-induced protein IG-H3 (P82198), a secreted TGF␤3-induced protein that binds collagen in the extracellular matrix. Peptides derived from extracellular sources might load onto MHC II at the cell surface or intracellular locations with low DM activity and could represent a source of antigens for recognition by type B T cells (110). HLA-DM sensitivity and the fact that many of the MHC II-eluted peptides correspond to sequences known to be cleaved by extracellular proteases, such as complement 1, meprin, granzyme, MMPs, and ADAMS, point to the fact that the extracellular milieu/lymph is the likely source of many of the peptides eluted from HLA-DR1.…”

Section: Peptide Sourcementioning

confidence: 99%

“…Extracellularly processed peptides also have also been implicated in the generation of autoimmunity (110,116,123). The difference between tolerance and autoimmunity outcome likely will be determined by differences in peptide MHC II binding affinity/stability, thymic selection, Treg induction, peptide generation by de novo processing pathways, and the nature of the presenting APC.…”

Section: Peptide Sourcementioning

confidence: 99%

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The Dendritic Cell Major Histocompatibility Complex II (MHC II) Peptidome Derives from a Variety of Processing Pathways and Includes Peptides with a Broad Spectrum of HLA-DM Sensitivity

Clement¹,

Becerra²,

Yin³

et al. 2016

Journal of Biological Chemistry

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The repertoire of peptides displayed in vivo by MHC II molecules derives from a wide spectrum of proteins produced by different cell types. Although intracellular endosomal processing in dendritic cells and B cells has been characterized for a few antigens, the overall range of processing pathways responsible for generating the MHC II peptidome are currently unclear. To determine the contribution of non-endosomal processing pathways, we eluted and sequenced over 3000 HLA-DR1-bound peptides presented in vivo by dendritic cells. The processing enzymes were identified by reference to a database of experimentally determined cleavage sites and experimentally validated for four epitopes derived from complement 3, collagen II, thymosin ␤4, and gelsolin. We determined that self-antigens processed by tissue-specific proteases, including complement, matrix metalloproteases, caspases, and granzymes, and carried by lymph, contribute significantly to the MHC II selfpeptidome presented by conventional dendritic cells in vivo. Additionally, the presented peptides exhibited a wide spectrum of binding affinity and HLA-DM susceptibility. The results indicate that the HLA-DR1-restricted self-peptidome presented under physiological conditions derives from a variety of processing pathways. Non-endosomal processing enzymes add to the number of epitopes cleaved by cathepsins, altogether generating a wider peptide repertoire. Taken together with HLA-DM-dependent andindependent loading pathways, this ensures that a broad self-peptidome is presented by dendritic cells. This work brings attention to the role of "self-recognition" as a dynamic interaction between dendritic cells and the metabolic/catabolic activities ongoing in every parenchymal organ as part of tissue growth, remodeling, and physiological apoptosis.

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Activation of Type B T Cells after Protein Immunization Reveals Novel Pathways of In Vivo Presentation of Peptides

Cited by 24 publications

References 35 publications

Comparing Pooled Peptides with Intact Protein for Accessing Cross-presentation Pathways for Protective CD8+ and CD4+ T Cells

Comparing Pooled Peptides with Intact Protein for Accessing Cross-presentation Pathways for Protective CD8+ and CD4+ T Cells

Specificity and detection of insulin-reactive CD4⁺T cells in type 1 diabetes in the nonobese diabetic (NOD) mouse

The Dendritic Cell Major Histocompatibility Complex II (MHC II) Peptidome Derives from a Variety of Processing Pathways and Includes Peptides with a Broad Spectrum of HLA-DM Sensitivity

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Activation of Type B T Cells after Protein Immunization Reveals Novel Pathways of In Vivo Presentation of Peptides

Cited by 24 publications

References 35 publications

Comparing Pooled Peptides with Intact Protein for Accessing Cross-presentation Pathways for Protective CD8+ and CD4+ T Cells

Comparing Pooled Peptides with Intact Protein for Accessing Cross-presentation Pathways for Protective CD8+ and CD4+ T Cells

Specificity and detection of insulin-reactive CD4+T cells in type 1 diabetes in the nonobese diabetic (NOD) mouse

The Dendritic Cell Major Histocompatibility Complex II (MHC II) Peptidome Derives from a Variety of Processing Pathways and Includes Peptides with a Broad Spectrum of HLA-DM Sensitivity

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Product

Resources

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Specificity and detection of insulin-reactive CD4⁺T cells in type 1 diabetes in the nonobese diabetic (NOD) mouse