IgE In Allergic Diseases Research Articles

An Omalizumab Biobetter Antibody With Improved Stability and Efficacy for the Treatment of Allergic Diseases.

The critical role of IgE in allergic diseases is well-documented and clinically proven. Omalizumab, a humanized anti-IgE antibody, was the first approved antibody for the treatment of allergic diseases. Nevertheless, omalizumab still has some limitations, such as product instability and dosage restriction in clinical application. In this study, we attempted to develop an omalizumab biobetter antibody with the potential to overcome its limitations. We removed two aspartic acid isomerization hotspots in CDRs of omalizumab to improve antibody candidate’s stability. Meanwhile, several murine amino acids in the framework region of omalizumab were replaced with human source to reduce the potential immunogenicity. Yeast display technology was then applied to screen antibody candidates with high binding affinity to IgE. Moreover, YTE mutation in Fc fragment was introduced into the candidates for extending their serum half-life. A lead candidate, AB1904Am15, was screened out, which showed desired biophysical properties and improved stability, high binding affinity and elevated potency in vitro, prolonged half-life in human FcRn transgenic mouse, and enhanced in vivo efficacy in cynomolgus monkey asthma model. Overall, our study developed a biobetter antibody of omalizumab, AB1904Am15, which has the potential to show improved clinical benefit in the treatment of allergic diseases.

The roles of IgE in allergic diseases

The roles of IgE in allergic diseases

Plasma Cells and Nonplasma B Cells Express Differing IgE Repertoires in Allergic Sensitization

The selection of allergen-specific B cells into the plasma cell (PC) pool is a critical step in the immune dysregulation that leads to the production of IgE in allergic diseases. We sought to characterize the murine IgE repertoire. In particular, we questioned whether the IgE repertoire of plasmablasts (PBs)/PCs differs from the IgE repertoire of non-PCs. Therefore, we sorted splenocytes from OVA-sensitized BALB/c mice into CD138(pos) (PBs/PCs) and CD19(pos)/CD138(neg) (non-PCs) B cell fractions. Using reverse transcription PCR, we amplified, cloned, and sequenced IgE mRNA transcripts and analyzed the Ig H chain repertoire. As a reference, we characterized the IgM repertoire of the same animals. Compared to IgM, the IgE sequences contained a significantly higher level of somatic mutations and displayed an oligoclonal expansion with clonotype restriction. Interestingly, we found two phenotypically distinct IgE-producing B cell subpopulations that differed in their repertoire of H chain transcripts; IgE transcripts from PBs/PCs showed significantly more signs of Ag-driven selection than transcripts from non-PCs, including 1) a higher number of somatic mutations, 2) increased clustering of replacement mutations in the CDRs, and 3) biased third CDR of the heavy Ig chain composition. In conclusion, PBs/PCs and non-PCs from OVA-sensitized mice express distinct IgE repertoires, suggesting that 1) the repertoire of IgE-expressing PBs/PCs represents a highly biased selection from the global B cell repertoire and 2) Ag-driven affinity maturation is a major force that selects IgE-producing B cells into the CD138(pos) PC pool.

Immunogenetic characteristics of immunoglobulin E in allergic disease

Patients with allergic diseases produce an excess of allergen-specific IgE, the specific effector molecule that triggers allergic reactions. The provocation for this excess IgE production is still uncertain. Current ideas include oligoclonal expansion of allergen-specific B cells emanating from germinal centres, activation by superantigen of a subset of B cells, or polyclonal B cells class switching to IgE due to an IL-4 predominance. Additionally, genetic elements contribute to a propensity for increased allergen-specific IgE production. The procedure of RT-PCR allows for amplification of infrequent IgE mRNA transcripts from B cells of atopic individuals, and so facilitates examination of expressed Ig cDNA sequences. Better knowledge of the molecular characteristics of IgE produced by patients with allergic diseases would elucidate the immunogenetic basis for elevated allergen-specific IgE levels. The 'immunogenetic footprint' of IgE transcripts may elucidate the origin and activation of IgE-producing B cells in allergic disease. Here we review studies of the immunogenetic features of IgE in allergic diseases, highlighting the major advances and the experimental limitations.

Targeting immunoglobulin E as a novel treatment for asthma

Omalizumab is a recently developed monoclonal anti-IgE antibody. Clinical trials have demonstrated its efficacy in patients with moderate-to-severe and severe or poorly controlled allergic asthma, in patients with seasonal and perennial allergic disease, and in subjects with concomitant asthma and allergic rhinitis. Patients with more severe asthma appear to obtain the greatest benefit from omalizumab therapy. Omalizumab is well tolerated and has a good safety profile. Anti-inflammatory activity has been shown in both allergic asthma and allergic rhinitis. These results confirm the importance of IgE in allergic disease and support the rationale behind the development of a therapeutic anti-IgE antibody. Omalizumab is a significant addition to current asthma treatments and shows great promise as a therapy for allergic rhinitis, in particular for those patients with concomitant allergic disease.

CD45 Controls Interleukin-4-mediated IgE Class Switch Recombination in Human B Cells through Its Function as a Janus Kinase Phosphatase

CD45 plays a critical regulatory role in receptor signaling through its protein tyrosine phosphatase and Janus kinase (JAK) phosphatase activities. To investigate whether CD45 also plays a regulatory role in Ig class switching in human B cells, we examined the effects of CD45 triggering on Ig class switching to IgE and its relationship with CD45 JAK phosphatase activity. Anti-CD45 triggering of CD45 significantly inhibited interleukin-4 + anti-CD40-induced switch recombination in a switch recombination vector assay in stably transfected Ramos 2G6 human B cells, as well as Ig epsilon germ-line transcription and Smu-Sepsilon switch recombination in primary human B cells. These negative regulatory effects on Ig class switching were concomitant with the ability of CD45 to dephosphorylate the induced phosphorylation of JAK1, JAK3, and signal transducer and activator of transcription 6, but not on stress-activated/mitogen-activated protein kinases. We also showed that phosphorylated JAK1 and JAK3 were directly dephosphorylated by recombinant CD45 in vitro. These results indicate that CD45 is able to function as JAK phosphatase in human B cells and that this activity is directly associated with the negative regulation of the class switch recombination to IgE. CD45 may be an appropriate target drug for modulating IgE in allergic diseases.

Treating Asthma with Anti-IgE or Anti-IL5

In the last decades, several key mechanisms driving asthma pathophysiooogy have been discovered. These include the role of IgE in allergic disease, and the role of IL-5 in eosinophilic inflammation. In the last few years, tools to block each of these have been developed. At this time, early clinical studies with neutralizing antibodies against both IgE and IL-5 have been performed in asthma patients, with promising results, and larger studies are underway. The mechanisms of, and possible role of, both anti-IgE and anti-IL-5 treatment in asthma are discussed in this review article.

Regulation of IgE synthesis.

The role of IgE in allergic disease is by now well recognized. The study of the cellular basis of IgE regulation has been actively pursued to gain insights into the pathogenesis of a disease that affects a considerable proportion of the population. More recently, the molecular events underlying IgE synthesis have become the focus of intense interest, in an attempt to characterize the signals involved in isotype-specific regulation of immunoglobulin synthesis. Recent evidence from different laboratories indicates that induction of IgE synthesis requires two signals: one is IgE isotype-specific, and is delivered by IL-4, the other is a B cell activating signal that can be delivered through a variety of pathways. We will herein review what is currently known about the mechanisms underlying the synthesis of IgE in humans, as they are revealed through cellular and molecular biology studies.

Regulation of IgE synthesis in humans: A tale of two signals

It is an unambiguous sign of vitality for a field when reviews become rapidly obsolete. After a decade of relatively slow progress, this is happening in the field of IgE regulation. After years of cell and cytokine cocktails, molecular biology is now providing an insight into the IgE system at a deeper, more meaningful level. The study of IgE regulation becomes important now not only because of the role of IgE in allergic disease but also, more generally, as a model to study the signals involved in isotype-specific regulation of immunoglobulin synthesis. In the past 2 to 3 years, evidence from different laboratories has indicated that induction of IgE synthesis requires two signals: One is delivered by a cytokine, IL-4, and is IgE isotype specific. The other signal is a B cell-activating signal.’ The challenge in IgE studies now is to determine what role the two signals play in the induction of IgE synthesis at the level of gene regulation.

Diagnosis and immunotherapy of mould allergy

The IgE-response was evaluated by skin prick test, bronchial provocation test and RAST in a 1-year placebo-controlled double-blind immunotherapy study. Eleven adult asthmatics were treated with a Cladosporium allergen preparation and 11 comparable patients received histamine placebo. The bronchial sensitivity (PC20) decrease greater than 0.5 log step in 8/11 (73%) Cladosporium-treated versus 3/11 (27%) in the placebo group. Corresponding figures for skin prick test sensitivity was 10/11 (91%) and 1/11 (9%) respectively. Circulating IgE showed a temporary boost in the Cladosporium group and then values approaching the pretreatment value. Only minimal and insignificant changes were found in the placebo-treated patients. Changes in IgE-reactivity were not related to allergen dose, clinical efficacy or to the occurrence of side effects. Some interrelation between changes in skin prick test, bronchial provocation test and RAST was found indicating a differentiated effect of immunotherapy on various IgE compartments. In spite of the pathogenetic role of IgE in allergic diseases, changes in IgE-reactivity do not seem directly involved in the mechanisms underlying the clinical efficacy of immunotherapy but might be of importance in a complex interaction with other immunological parameters.

IgE in Allergic Disease in a Veteran Population

IgE in Allergic Disease in a Veteran Population