Small Molecule/HLA Complexes Alter the Cellular Proteomic Content

A medical product usually undergoes several clinical trials, including the testing of volunteers. Nevertheless, genomic variances in the patients cannot be considered comprehensively and adverse drug reactions (ADRs) are missed or misinterpreted during trials. Despite the relation between ADRs and human leukocyte antigen (HLA) molecules being known for several years, the fundamental molecular mechanisms leading to the development of such an ADR often remains only vaguely solved. The analysis of the peptidome can reveal changes in peptide presentation post-drug treatment and explain, for example, the severe cutaneous ADR in HLA-B*57:01-positive patients treated with the antiretroviral drug abacavir in anti-HIV therapy. However, as seen in the biophysical features of HLA-A*31:01-presented peptides, treatment with the anticonvulsant carbamazepine only induces minor changes. Since the binding of a drug to a certain HLA allelic variant is extremely distinct, the influence of the small molecule/protein complex on the proteomic content of a cell becomes clear. A sophisticated methodology elucidating the impact of drug treatment on cells is a full proteome analysis. The principal component analysis of abacavir, carbamazepine or carbamazepine-10,11-epoxid treated cells reveals clear clustering of the drug-treated and the untreated samples that express the respective HLA molecule. Following drug treatment, several proteins were shown to be significantly up- or downregulated. Proteomics and peptidomics are valuable tools to differential clinical outcomes of patients with the same HLA phenotype.