Bioinspired Design and Oriented Synthesis of Immunogenic Site-Specifically Penicilloylated Peptides.

ß-Lactam antibiotics allergy is recognized as a public health concern. By covalently binding to serum proteins, penicillins are known to form immunogenic complexes. The latter are recognized and digested by antigen-presenting cells into drug-hapten peptides leading to the immunization of treated persons and IgE-mediated hypersensitivity reactions encompassing anaphylaxis. If type I allergic reactions to drugs are often unpredictable, they are known to be dependent on CD4+ T-cells. This fundamental study revisits the chemical basis of the benzylpenicillin (BP) allergy with the aim of identifying immunologically relevant biomimetic benzylpenicilloylated peptides through the analysis of BP-conjugated human serum albumin (BP-HSA) profile and the evaluation of the naïve CD4+ T-cell responses to candidate BP-HSA-derived peptides. The chemical structures of BP-HSA bioconjugates synthesized in vitro at both physiological and basic pH were investigated by mass spectrometry. From the ten most representative lysine residues grafted by BP-hapten, HSA-bioinspired 15-mer peptide sequences were designed and the potential T-cell epitope profile of each peptide was predicted using two complementary in silico approaches, i.e., HLA class II binding prediction tools from the Immune Epitope Database and Analysis Resource (IEDB) and computational alanine scanning mutagenesis. Twelve structurally diversified benzylpenicilloylated peptides (BP-Ps) were selected and synthesized with the aid of a flexible synthesis pathway using an original benzylpenicilloylated lysine monomer as common precursor. In order to corroborate their predicted "epitope" profile, the naïve CD4+ T-cell response specific to BP was evaluated through a coculture approach. To our knowledge, this study showed for the first time the ability of bioinspired peptides structurally stemming from BP-HSA to be recognized by naïve CD4+ T-cells thus identifying a pre-existing T-cell repertoire for penicillin molecules bound to proteins. It also established a promising model approach expandable to other most frequently used penicillin classes of antibiotics to reveal biomimetic drug-modified antigenic peptides relevant for qualitative and quantitative drug allergy studies.

C(16)-methyl corticosteroids are far less allergenic than the non-methylated molecules.

BACKGROUND: It has been confirmed that binding to amino acids in skin proteins takes place at C(21) after oxidation of the corticosteroid molecule, which gives to the constituents of the D-ring an essential role in cross-reactivity patterns. In 2000, Matura et al. subdivided the corticosteroid esters of the D-group into two subgroups: D1, the 'stable' esters; and D2, the 'labile' esters. Recent data have indicated that non-methylated corticosteroids selectively react with arginine to form stable cyclic adducts, which are probably implicated in sensitization to corticosteroids. OBJECTIVES: To compare the patch test results and reactivity of C(16)-methylated and non-methylated corticosteroids. METHODS: Three hundred and fifteen subjects with a proven corticosteroid contact allergy underwent patch testing with an extended corticosteroid series. Statistical analysis was performed with the Wilcoxon signed rank test to compare the number of reactions to molecules with and without C(16)-methyl substitution. RESULTS: Positive patch test reactions to corticosteroid molecules without C(16)-methyl substitution groups A and D2, were, with statistical significance, much more frequently observed than to those with a C(16)-methyl group, groups D1 and C. CONCLUSIONS: C(16)-methyl substitution, interfering with protein binding, and halogenation, seem to reduce the allergenicity of corticosteroid molecules. Hence, when indicated, C(16)-methylated corticosteroids should be preferentially prescribed.

Delayed hypersensitivity to corticosteroids in a series of 315 patients: clinical data and patch test results.

BACKGROUND: Corticosteroids may cause immediate or delayed hypersensitivity. In 1989, based on structural and clinical characteristics, we put forward a classification of corticosteroids into four cross-reacting groups, namely group A, B, C, and D, the latter later subdivided into two subgroups, i.e. D1 and D2. The constituents on the D-ring of the corticosteroid-molecule are considered to have a central role for binding to skin proteins and for cross-reactions patterns; however, halogenation of the molecules is also interfering. OBJECTIVE: To study the clinical data and analyse simultaneous positive reactions obtained in a large group of corticosteroid-allergic patients. METHODS: Patch tests were performed with the baseline series, to which hydrocortisone butyrate and prednisolone caproate were added, as well as with the corticosteroids to which the patients had been exposed. Three hundred and forty subjects with a presumed or proven corticosteroid allergy were further investigated with an extended series containing 72 molecules. RESULTS: Out of 11 596 patients investigated, 315 subjects reacted positively to at least 1 corticosteroid-molecule, with most of them presenting with multiple positive reactions. CONCLUSION: A prevalence of corticosteroid allergy of 2.7% was found. Despite validity of the ABCD (sub)classification in many cases, possible adjustments may have to be considered.

Interhelical loops within the bHLH domain are determinant in maintaining TWIST1-DNA complexes.

The basic helix-loop-helix (bHLH) transcription factor TWIST1 is essential to embryonic development, and hijacking of its function contributes to the development of numerous cancer types. It forms either a homodimer or a heterodimeric complex with an E2A or HAND partner. These functionally distinct complexes display sometimes antagonistic functions during development, so that alterations in the balance between them lead to pronounced morphological alterations, as observed in mice and in Saethre-Chotzen syndrome patients. We, here, describe the structures of TWIST1 bHLH-DNA complexes produced in silico through molecular dynamics simulations. We highlight the determinant role of the interhelical loops in maintaining the TWIST1-DNA complex structures and provide a structural explanation for the loss of function associated with several TWIST1 mutations/insertions observed in Saethre-Chotzen syndrome patients. An animated interactive 3D complement (I3DC) is available in Proteopedia at http://proteopedia.org/w/Journal:JBSD:27.