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Non-mutated FVIII-specific CD4 T cell epitopes have been recently found to contribute to the development of inhibitors in patients with hemophilia A (HA), while auto-reactive CD4 T cells specific to FVIII circulate in the blood of healthy individuals at a frequency close to the foreign protein ovalbumin. Thus, although FVIII is a self-protein, the central tolerance raised against FVIII appears to be low. In this study, we conducted a comprehensive analysis of the FVIII CD4 T cell repertoire in 29 healthy donors. Sequencing of the CDR3β TCR region from isolated FVIII-specific CD4 T cells revealed a limited usage and pairing of TRBV and TRBJ genes as well as a mostly hydrophobic composition of the CDR3β region according to their auto-reactivity. The FVIII repertoire is dominated by a few clonotypes, with only 13 clonotypes accounting for half of the FVIII response. Through a large-scale epitope mapping of the full-length FVIII sequence, we identified 18 immunodominant epitopes located in the A1, A3, C1, and C2 domains and covering half of the T cell response. These epitopes exhibited a broad specificity for HLA-DR or DP molecules or both. T cell priming with this reduced set of peptides revealed that highly expanded clonotypes specific to these epitopes were responsible individually for up to 32% of the total FVIII repertoire. These FVIII T cell epitopes and clonotypes were shared among HLA-unrelated donors tested and previously reported HA patients. Our study highlights the role of the auto-reactive T cell response against FVIII in HA and its similarity to the response observed in healthy individuals. Thus, it provides valuable insights for the development of new tolerance induction and deimmunization strategies.

This study provides an in-depth analysis of the diversity of the CD4 TCR CDR3β repertoire specific to influenza A (HA) and Epstein-Barr virus (EBNA) epitopes. Epitope-specific CD4 T cells from 13 healthy donors were enriched using a short-term culture step, isolated based on activation markers, and sequenced for their TCR CDR3β region using high-throughput sequencing. The frequency of each clonotype was then identified within the complete circulating CD4 T-cell CDR3β repertoire. For both epitopes, the clonotype distribution was markedly skewed, with a small number of highly expanded clones comprising approximately 60% of the repertoire, alongside numerous low-frequency clonotypes. VJ gene usage and motif preferences differed between the two peptides, highlighting epitope-specific TCR selectivity. The response was predominantly composed of private T-cell clonotypes. The proportion of public clonotypes can increase among donors sharing HLA class II molecules and reveals in HLA-unrelated donors the level of TCR promiscuity. Overall, our data demonstrate that CD4 T-cell responses to these viral epitopes are polyclonal and highly personalized. The modest overlap of clonotypes between donors, coupled with a long tail of low-frequency clones, suggests that the full diversity of the epitope-specific T-cell repertoire is likely broader than previously estimated.

Rationale The role of ethanol-derived acetaldehyde has not been examined yet on performance in a model of operant oral self-administration. However, previous studies reported that an acetaldehyde-sequestering agent, d -penicillamine (DP) and an inhibitor of catalase-mediated acetaldehyde production, 3-amino-1,2,4-triazole (3-AT) reduce voluntary ethanol consumption. Objectives The aim of our investigation was to evaluate the effects of DP and 3-AT on acquisition and maintenance of oral operant ethanol self-administration. Methods Using operant chambers, rats learned to nose poke in order to receive ethanol solution (5–10 % v / v ) under an FR1 schedule of reinforcement in which discrete light and tone cues were presented during ethanol delivery. Results DP and 3-AT impair the acquisition of ethanol self-administration, whereas its maintenance is not affected neither by drug given alone for both 10 or 5 % ethanol nor by drugs association for 5 % ethanol. Moreover, when the concentration of ethanol was diminished from 10 to 5 %, rats increased the rate of self-administration behaviour. Conclusions These findings suggest that brain acetaldehyde plays a critical role during acquisition of operant self-administration in ethanol-naïve rats. In contrast, during the maintenance phase, acetaldehyde could contribute to ethanol self-administration by a combined mechanism: On one hand, its lack (by DP or 3-AT) might result in further ethanol-seeking and taking and, on the other, inhibition of ethanol metabolism (by 3-AT) might release an action of the un-metabolised fraction of ethanol that does not overall result in compromising maintenance of ethanol self-administration.

The role of ethanol-derived acetaldehyde has not been examined yet on performance in a model of operant oral self-administration. However, previous studies reported that an acetaldehyde-sequestering agent, d-penicillamine (DP) and an inhibitor of catalase-mediated acetaldehyde production, 3-amino-1,2,4-triazole (3-AT) reduce voluntary ethanol consumption. The aim of our investigation was to evaluate the effects of DP and 3-AT on acquisition and maintenance of oral operant ethanol self-administration. Using operant chambers, rats learned to nose poke in order to receive ethanol solution (5-10 % v/v) under an FR1 schedule of reinforcement in which discrete light and tone cues were presented during ethanol delivery. DP and 3-AT impair the acquisition of ethanol self-administration, whereas its maintenance is not affected neither by drug given alone for both 10 or 5 % ethanol nor by drugs association for 5 % ethanol. Moreover, when the concentration of ethanol was diminished from 10 to 5 %, rats increased the rate of self-administration behaviour. These findings suggest that brain acetaldehyde plays a critical role during acquisition of operant self-administration in ethanol-naïve rats. In contrast, during the maintenance phase, acetaldehyde could contribute to ethanol self-administration by a combined mechanism: On one hand, its lack (by DP or 3-AT) might result in further ethanol-seeking and taking and, on the other, inhibition of ethanol metabolism (by 3-AT) might release an action of the un-metabolised fraction of ethanol that does not overall result in compromising maintenance of ethanol self-administration.

The role of ethanol-derived acetaldehyde has not been examined yet on performance in a model of operant oral self-administration. However, previous studies reported that an acetaldehyde-sequestering agent, d-penicillamine (DP) and an inhibitor of catalase-mediated acetaldehyde production, 3-amino-1,2,4-triazole (3-AT) reduce voluntary ethanol consumption. The aim of our investigation was to evaluate the effects of DP and 3-AT on acquisition and maintenance of oral operant ethanol self-administration. Using operant chambers, rats learned to nose poke in order to receive ethanol solution (5-10 % v/v) under an FR1 schedule of reinforcement in which discrete light and tone cues were presented during ethanol delivery. DP and 3-AT impair the acquisition of ethanol self-administration, whereas its maintenance is not affected neither by drug given alone for both 10 or 5 % ethanol nor by drugs association for 5 % ethanol. Moreover, when the concentration of ethanol was diminished from 10 to 5 %, rats increased the rate of self-administration behaviour. These findings suggest that brain acetaldehyde plays a critical role during acquisition of operant self-administration in ethanol-naïve rats. In contrast, during the maintenance phase, acetaldehyde could contribute to ethanol self-administration by a combined mechanism: On one hand, its lack (by DP or 3-AT) might result in further ethanol-seeking and taking and, on the other, inhibition of ethanol metabolism (by 3-AT) might release an action of the un-metabolised fraction of ethanol that does not overall result in compromising maintenance of ethanol self-administration.