scholarly journals A high-affinity human TCR-like antibody detects celiac disease gluten peptide–MHC complexes and inhibits T cell activation

2021 ◽  
Vol 6 (62) ◽  
pp. eabg4925
Author(s):  
Rahel Frick ◽  
Lene S. Høydahl ◽  
Jan Petersen ◽  
M. Fleur du Pré ◽  
Shraddha Kumari ◽  
...  
Keyword(s):  
Celiac Disease ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Therapeutic Potential ◽  
Human Leukocyte ◽  
Fab Fragment ◽  
Biopsy Material ◽  
Human T Cell

Antibodies specific for peptides bound to human leukocyte antigen (HLA) molecules are valuable tools for studies of antigen presentation and may have therapeutic potential. Here, we generated human T cell receptor (TCR)–like antibodies toward the immunodominant signature gluten epitope DQ2.5-glia-α2 in celiac disease (CeD). Phage display selection combined with secondary targeted engineering was used to obtain highly specific antibodies with picomolar affinity. The crystal structure of a Fab fragment of the lead antibody 3.C11 in complex with HLA-DQ2.5:DQ2.5-glia-α2 revealed a binding geometry and interaction mode highly similar to prototypic TCRs specific for the same complex. Assessment of CeD biopsy material confirmed disease specificity and reinforced the notion that abundant plasma cells present antigen in the inflamed CeD gut. Furthermore, 3.C11 specifically inhibited activation and proliferation of gluten-specific CD4+ T cells in vitro and in HLA-DQ2.5 humanized mice, suggesting a potential for targeted intervention without compromising systemic immunity.

scholarly journals Signaling function of PRC2 is essential for TCR-driven T cell responses

2018 ◽  
Vol 215 (4) ◽  
pp. 1101-1113 ◽  
Author(s):  
Marc-Werner Dobenecker ◽  
Joon Seok Park ◽  
Jonas Marcello ◽  
Michael T. McCabe ◽  
Richard Gregory ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Therapeutic Potential ◽  
Cell Types ◽  
Polycomb Repressive Complex 2 ◽  
Histone Lysine Methyltransferases

Differentiation and activation of T cells require the activity of numerous histone lysine methyltransferases (HMT) that control the transcriptional T cell output. One of the most potent regulators of T cell differentiation is the HMT Ezh2. Ezh2 is a key enzymatic component of polycomb repressive complex 2 (PRC2), which silences gene expression by histone H3 di/tri-methylation at lysine 27. Surprisingly, in many cell types, including T cells, Ezh2 is localized in both the nucleus and the cytosol. Here we show the presence of a nuclear-like PRC2 complex in T cell cytosol and demonstrate a role of cytosolic PRC2 in T cell antigen receptor (TCR)–mediated signaling. We show that short-term suppression of PRC2 precludes TCR-driven T cell activation in vitro. We also demonstrate that pharmacological inhibition of PRC2 in vivo greatly attenuates the severe T cell–driven autoimmunity caused by regulatory T cell depletion. Our data reveal cytoplasmic PRC2 is one of the most potent regulators of T cell activation and point toward the therapeutic potential of PRC2 inhibitors for the treatment of T cell–driven autoimmune diseases.

scholarly journals GABAA receptor α4-subunit knockout enhances lung inflammation and airway reactivity in a murine asthma model

2017 ◽  
Vol 313 (2) ◽  
pp. L406-L415 ◽  
Author(s):  
Gene T. Yocum ◽  
Damian L. Turner ◽  
Jennifer Danielsson ◽  
Matthew B. Barajas ◽  
Yi Zhang ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Activation ◽  
Immune Cells ◽  
Cell Activation ◽  
Cell Function ◽  
Immune Cell ◽  
Therapeutic Potential ◽  
Ex Vivo ◽  
Asthma Model

Emerging evidence indicates that hypnotic anesthetics affect immune function. Many anesthetics potentiate γ-aminobutyric acid A receptor (GABAAR) activation, and these receptors are expressed on multiple subtypes of immune cells, providing a potential mechanistic link. Like immune cells, airway smooth muscle (ASM) cells also express GABAARs, particularly isoforms containing α4-subunits, and activation of these receptors leads to ASM relaxation. We sought to determine if GABAAR signaling modulates the ASM contractile and inflammatory phenotype of a murine allergic asthma model utilizing GABAAR α4-subunit global knockout (KO; Gabra40/0) mice. Wild-type (WT) and Gabra4 KO mice were sensitized with house dust mite (HDM) antigen or exposed to PBS intranasally 5 days/wk for 3 wk. Ex vivo tracheal rings from HDM-sensitized WT and Gabra4 KO mice exhibited similar magnitudes of acetylcholine-induced contractile force and isoproterenol-induced relaxation ( P = not significant; n = 4). In contrast, in vivo airway resistance (flexiVent) was significantly increased in Gabra4 KO mice ( P < 0.05, n = 8). Moreover, the Gabra4 KO mice demonstrated increased eosinophilic lung infiltration ( P < 0.05; n = 4) and increased markers of lung T-cell activation/memory (CD62L low, CD44 high; P < 0.01, n = 4). In vitro, Gabra4 KO CD4+ cells produced increased cytokines and exhibited increased proliferation after stimulation of the T-cell receptor as compared with WT CD4+ cells. These data suggest that the GABAAR α4-subunit plays a role in immune cell function during allergic lung sensitization. Thus GABAAR α4-subunit-specific agonists have the therapeutic potential to treat asthma via two mechanisms: direct ASM relaxation and inhibition of airway inflammation.

Cobalt-chromium-molybdenum but not titanium-6aluminium-4vanadium alloy discs inhibit human t cell activation in vitro

BioMetals ◽  
1996 ◽  
Vol 9 (4) ◽  
pp. 321-326 ◽  
Author(s):  
Cristina Faleiro ◽  
Inês Godinho ◽  
Ulrich Reus ◽  
Maria de Sousa
Keyword(s):  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Cobalt Chromium ◽  
Human T Cell ◽  
Cobalt Chromium Molybdenum

scholarly journals In Vitro Monitoring of Human T Cell Responses to Skin Sensitizing Chemicals—A Systematic Review

Cells ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 83
Author(s):  
Marina Aparicio-Soto ◽  
Caterina Curato ◽  
Franziska Riedel ◽  
Hermann-Josef Thierse ◽  
Andreas Luch ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Cross Reactivity ◽  
T Cell Epitopes ◽  
Cell Responses ◽  
Human T Cell ◽  
The Individual

Background: Chemical allergies are T cell-mediated diseases that often manifest in the skin as allergic contact dermatitis (ACD). To prevent ACD on a public health scale and avoid elicitation reactions at the individual patient level, predictive and diagnostic tests, respectively, are indispensable. Currently, there is no validated in vitro T cell assay available. The main bottlenecks concern the inefficient generation of T cell epitopes and the detection of rare antigen-specific T cells. Methods: Here, we systematically review original experimental research papers describing T cell activation to chemical skin sensitizers. We focus our search on studies published in the PubMed and Scopus databases on non-metallic allergens in the last 20 years. Results: We identified 37 papers, among them 32 (86%) describing antigen-specific human T cell activation to 31 different chemical allergens. The remaining studies measured the general effects of chemical allergens on T cell function (five studies, 14%). Most antigen-specific studies used peripheral blood mononuclear cells (PBMC) as antigen-presenting cells (APC, 75%) and interrogated the blood T cell pool (91%). Depending on the individual chemical properties, T cell epitopes were generated either by direct administration into the culture medium (72%), separate modification of autologous APC (29%) or by use of hapten-modified model proteins (13%). Read-outs were mainly based on proliferation (91%), often combined with cytokine secretion (53%). The analysis of T cell clones offers additional opportunities to elucidate the mechanisms of epitope formation and cross-reactivity (13%). The best researched allergen was p-phenylenediamine (PPD, 12 studies, 38%). For this and some other allergens, stronger immune responses were observed in some allergic patients (15/31 chemicals, 48%), illustrating the in vivo relevance of the identified T cells while detection limits remain challenging in many cases. Interpretation: Our results illustrate current hardships and possible solutions to monitoring T cell responses to individual chemical skin sensitizers. The provided data can guide the further development of T cell assays to unfold their full predictive and diagnostic potential, including cross-reactivity assessments.

scholarly journals Cepharanthine Blocks Presentation of Thyroid and Islet Peptides in a Novel Humanized Autoimmune Diabetes and Thyroiditis Mouse Model

2021 ◽  
Vol 12 ◽  
Author(s):  
Cheuk Wun Li ◽  
Roman Osman ◽  
Francesca Menconi ◽  
Larissa C. Faustino ◽  
Kookjoo Kim ◽  
...  
Keyword(s):  
T Cell ◽  
Mouse Model ◽  
Small Molecules ◽  
T Cell Activation ◽  
Cell Activation ◽  
Therapeutic Potential ◽  
Autoimmune Diabetes ◽  
Autoimmune Response ◽  
Hla Dr3

Autoimmune polyglandular syndrome type 3 variant (APS3v) refers to an autoimmune condition in which both type 1 diabetes (T1D) and autoimmune thyroiditis (AITD) develop in the same individual. HLA-DR3 confers the strongest susceptibility to APS3v. Previously we reported a unique amino acid signature pocket that predisposes to APS3v. We found that this pocket is flexible and can trigger APS3v by presenting both thyroid (Tg.1571, TPO.758) and islet (GAD.492) peptides to induce autoimmune response. We hypothesized that blocking the specific APS3v-HLA-DR3 pocket from presenting thyroid/islet antigens can block the autoimmune response in APS3v. To test this hypothesis we performed a virtual screen of small molecules blocking APS3v-HLA-DR3, and identified 11 small molecules hits that were predicted to block APS3v-HLA-DR3. Using the baculovirus-produced recombinant APS3v-HLA-DR3 protein we tested the 11 small molecules in an in vitro binding assay. We validated 4 small molecule hits, S9, S5, S53 and S15, that could block the APS3v-HLA-DR3 pocket in vitro. We then developed a novel humanized APS3v mouse model induced by co-immunizing a peptide mix of Tg.1571, TPO.758 and GAD.492. The immunized mice developed strong T-cell and antibody responses to the thyroid/islet peptides, as well as mouse thyroglobulin. In addition, the mice showed significantly lower free T4 levels compared to controls. Using the APS3v mouse model, we showed that one of the 4 small molecules, Cepharanthine (S53), blocked T-cell activation by thyroid/islet peptides ex vivo and in vivo. These findings suggested Cepharanthine may have a therapeutic potential in APS3v patients carrying the specific APS3v-HLA-DR3 pocket.

scholarly journals Impact of HLA-DR Antigen Binding Cleft Rigidity on T Cell Recognition

2020 ◽  
Vol 21 (19) ◽  
pp. 7081
Author(s):  
Christopher Szeto ◽  
Joseph I. Bloom ◽  
Hannah Sloane ◽  
Christian A. Lobos ◽  
James Fodor ◽  
...  
Keyword(s):  
T Cell ◽  
Protein Stability ◽  
T Cell Activation ◽  
Cell Activation ◽  
Human Leukocyte ◽  
Antigen Binding ◽  
Hla Class I Molecules ◽  
Hla Dr ◽  
Binding Cleft

The interaction between T cell receptor (TCR) and peptide (p)-Human Leukocyte Antigen (HLA) complexes is the critical first step in determining T cell responses. X-ray crystallographic studies of pHLA in TCR-bound and free states provide a structural perspective that can help understand T cell activation. These structures represent a static “snapshot”, yet the nature of pHLAs and their interactions with TCRs are highly dynamic. This has been demonstrated for HLA class I molecules with in silico techniques showing that some interactions, thought to stabilise pHLA-I, are only transient and prone to high flexibility. Here, we investigated the dynamics of HLA class II molecules by focusing on three allomorphs (HLA-DR1, -DR11 and -DR15) that are able to present the same epitope and activate CD4+ T cells. A single TCR (F24) has been shown to recognise all three HLA-DR molecules, albeit with different affinities. Using molecular dynamics and crystallographic ensemble refinement, we investigate the molecular basis of these different affinities and uncover hidden roles for HLA polymorphic residues. These polymorphisms were responsible for the widening of the antigen binding cleft and disruption of pHLA-TCR interactions, underpinning the hierarchy of F24 TCR binding affinity, and ultimately T cell activation. We expanded this approach to all available pHLA-DR structures and discovered that all HLA-DR molecules were inherently rigid. Together with in vitro protein stability and peptide affinity measurements, our results suggest that HLA-DR1 possesses inherently high protein stability, and low HLA-DM susceptibility.

scholarly journals Differential effects of estradiol and progesterone on human T cell activation in vitro

2021 ◽  
Author(s):  
Georgia Papapavlou ◽  
Sandra Hellberg ◽  
Johanna Raffetseder ◽  
Jan Brynhildsen ◽  
Mika Gustafsson ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Differential Effects ◽  
Human T Cell

scholarly journals Affinity-engineered human antibodies detect celiac disease gluten pMHC complexes and inhibit T-cell activation

2019 ◽  
Author(s):  
Rahel Frick ◽  
Lene S. Høydahl ◽  
Ina Hodnebrug ◽  
Shraddha Kumari ◽  
Grete Berntsen ◽  
...  
Keyword(s):  
T Cells ◽  
Celiac Disease ◽  
T Cell ◽  
Antigen Presentation ◽  
T Cell Activation ◽  
Cell Activation ◽  
Plasma Cells ◽  
Human Antibodies ◽  
High Affinity

AbstractAntibodies specific for antigenic peptides bound to major histocompatibility complex (MHC) molecules are valuable tools for studies of antigen presentation. Such T-cell receptor (TCR)-like antibodies may also have therapeutic potential in human disease due to their ability to target disease-associated antigens with high specificity. We previously generated celiac disease (CeD) relevant TCR-like antibodies that recognize the prevalent gluten epitope DQ2.5-glia-α1a in complex with HLA-DQ2.5. Here, we report on second-generation high-affinity antibodies towards this epitope as well as a panel of novel TCR-like antibodies to another immunodominant gliadin epitope, DQ2.5-glia-α2. The strategy for affinity engineering was based on Rosetta modeling combined with pIX phage display and is applicable to similar protein engineering efforts. We isolated picomolar affinity binders and validated them in Fab and IgG format. Flow cytometry experiments with CeD biopsy material confirm the unique disease specificity of these TCR-like antibodies and reinforce the notion that B cells and plasma cells have a dominant role in gluten antigen presentation in the inflamed CeD gut. Further, the lead candidate 3.C11 potently inhibited CD4+ T-cell activation and proliferation in vitro in an HLA and epitope specific manner, pointing to a potential for targeted disease interception without compromising systemic immunity.Significance StatementConsumption of gluten-containing food drives celiac disease in genetically predisposed individuals. The underlying disease mechanism is not fully understood, but it is strictly dependent on activation of pathogenic T cells. We have engineered high-affinity human antibodies recognizing the T-cell target HLA-DQ2.5 in complex with gluten epitopes and studied cell-specific antigen presentation in patients, which shows that plasma cells and not dendritic cells dominate the inflamed tissue. The only available treatment is lifelong adherence to a gluten-free diet, which is difficult and not effective in all cases. We show that at least one of our antibodies can specifically inhibit activation of pathogenic T-cells in vitro and therefore shows promise for therapy.

Vaccination and Other Antigen-Specific Immunomodulatory Strategies in Celiac Disease

2015 ◽  
Vol 33 (2) ◽  
pp. 282-289 ◽  
Author(s):  
Mauro Rossi
Keyword(s):  
Immune Response ◽  
Celiac Disease ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Intestinal Biopsy ◽  
Small Intestinal Mucosa ◽  
Inflammatory Phenotype ◽  
Native Antigen

Background: Celiac disease (CD) results from an alteration in the oral tolerance to dietary gluten. The response to gluten is normally tightly regulated and involves the secretion of TGF-β and IL-10 from different subtypes of regulatory T cells (Tregs). Interestingly, in addition to proinflammatory cytokines, the inflamed CD mucosa also contains high levels of T cell-derived IL-10 compared with treated CD patients or normal donors. Furthermore, most studies describe an increase in the number of Foxp3+ Tregs in the small intestinal mucosa in CD patients compared to controls. This paradoxical condition suggests that regulatory mechanisms might operate to counterbalance the abnormal gliadin-triggered immune activation in untreated mucosa. Indeed, addition of exogenous IL-10 to mucosal cultures from treated CD patients can suppress gliadin-induced T cell activation. Considering the central role of adaptive immunity in CD, the development of strategies to stimulate these mechanisms is a primary goal of efforts to restore gluten tolerance. Key Messages: Different immunomodulatory strategies have been explored. NexVax2, a desensitizing vaccine that uses three dominant gluten peptides administered subcutaneously to induce a tolerogenic response in CD patients, is under development. Alternatively, the potential of substituted, cyclic or dimeric peptide analogues as blockers to prevent HLA from binding to the immunodominant gliadin epitopes has been demonstrated in vitro. In line with these results, we recently found that modified (transamidated) gliadins influenced the immune response in intestinal biopsy samples from CD patients with overt disease by drastically reducing the production of IFN-γ. Notably, in a mouse model, transamidated gliadins reverted the phenotype of the gliadin-inducible immune response from an inflammatory phenotype to an anti-inflammatory phenotype. Conclusions: Various approaches are currently under investigation to recover gluten tolerance based on the use of both modified and native antigen molecules. More specific studies are now required to test the efficacy of such strategies for preventing CD.

Sign in / Sign up

Export Citation Format

Share Document