IgE-tailpiece associates with α-1-antitrypsin (A1AT) to protect IgE from proteolysis without compromising its ability to interact with FcεRI

Ceruloplasmin and oxidative stress in severe eosinophilic asthma patients treated with Mepolizumab and Benralizumab

INTRODUCTION

Severe eosinophilic asthma has been associated with Th2 airway inflammation and elevated proinflammatory cytokines and chemokines, such as IL-5. Precision therapies have recently been shown to improve asthma symptoms with a steroid-sparing effect. Two such therapies, Benralizumab and Mepolizumab, humanized IgG antibodies directed against the IL-5 receptor and IL-5, have been approved for severe eosinophilic asthma.

METHODS

Here we used a differential proteomic approach to analyse serum from patients with severe eosinophilic asthma treated with Benralizumab and Mepolizumab in a search for differential molecular modifications responsible of their effects. Enrichment analysis of differential proteins was performed for the two treatments.

RESULTS AND DISCUSSION

After one month of Benralizumab treatment we detected up-regulation of certain protein species of the antioxidant ceruloplasmin. To investigate oxidative stress, we performed redox proteomics which detected lower oxidative burst after one month of Benralizumab treatment than in the pre-treatment phase or after one month of Mepolizumab therapy.

Engineering the fragment crystallizable (Fc) region of human IgG1 multimers and monomers to fine-tune interactions with sialic acid-dependent receptors

Multimeric fragment crystallizable (Fc) regions and Fc-fusion proteins are actively being explored as biomimetic replacements for IVIG therapy, which is deployed to manage many diseases and conditions but is expensive and not always efficient. The Fc region of human IgG1 (IgG1-Fc) can be engineered into multimeric structures (hexa-Fcs) that bind their cognate receptors with high avidity. The critical influence of the unique N-linked glycan attached at Asn-297 on the structure and function of IgG1-Fc is well documented; however, whether the N-linked glycan has a similarly critical role in multimeric, avidly binding Fcs, is unknown. Hexa-Fc contains two N-linked sites at Asn-77 (equivalent to Asn-297 in the Fc of IgG1) and Asn-236 (equivalent to Asn-563 in the tail piece of IgM). We report here that glycosylation at Asn-297 is critical for interactions with Fc receptors and complement and that glycosylation at Asn-563 is essential for controlling multimerization. We also found that introduction of an additional fully occupied N-linked glycosylation site at the N terminus at position 1 (equivalent to Asp-221 in the Fc of IgG1) dramatically enhances overall sialic acid content of the Fc multimers. Furthermore, replacement of Cys-575 in the IgM tail piece of multimers resulted in monomers with enhanced sialic acid content and differential receptor-binding profiles. Thus insertion of additional N-linked glycans into either the hinge or tail piece of monomers or multimers leads to molecules with enhanced sialylation that may be suitable for managing inflammation or blocking pathogen invasion.

Half-life of IgE in serum and skin: Consequences for anti-IgE therapy in patients with allergic disease

We present results from clinical studies on plasma infusion done in the late 1970s in patients with hypogammaglobulinemia in which we documented the short half-life of both total and allergen-specific IgE in serum. The development of specific allergic sensitization in the skin of those patients followed by the gradual decrease in sensitization over 50 days was also documented. The data are included here along with a discussion of the existing literature about the half-life of IgE in both the circulation and skin. This rostrum reinterprets the earlier clinical studies in light of new insights and mechanisms that could explain the rapid removal of IgE from the circulation. These mechanisms have clinical implications that relate to the increasing use of anti-IgE mAbs for the treatment of allergic disease.