Antibodies targeting the shared cytokine receptor IL-1 receptor accessory protein invoke distinct mechanisms to block all cytokine signaling

Interleukin-1 (IL-1)-family cytokines are potent modulators of inflammation, coordinating a vast array of immunological responses across innate and adaptive immune systems. Dysregulated IL-1-family cytokine signaling, however, is involved in a multitude of adverse health effects, such as chronic inflammatory conditions, autoimmune diseases, and cancer. Within the IL-1 family of cytokines, six-IL-1α, IL-1β, IL-33, IL-36α, IL-36β, and IL-36γ-require the IL-1 receptor accessory protein (IL-1RAcP) as their shared co-receptor. Common features of cytokine signaling include redundancy of signaling pathways, sharing of cytokines and receptors, pleiotropy of the cytokines themselves, and multifaceted immune responses. Accordingly, targeting multiple cytokines simultaneously is an emerging therapeutic strategy and can provide advantages over targeting a single cytokine pathway. Here, we show that two monoclonal antibodies, CAN10 and 3G5, which target IL-1RAcP for broad blockade of all associated cytokines, do so through distinct mechanisms and provide therapeutic opportunities for the treatment of inflammatory diseases.

Blocking IL1, IL33 and IL36 signaling by an anti-IL1RAP antibody is an efficient anti-inflammatory treatment that improves heart function in a model of autoimmune myocarditis

The IL1 receptor accessory protein (IL1RAP) is a coreceptor for the IL1, IL33, and IL36 receptors. We have developed a fully humanized antibody (CAN10) that binds IL1RAP with high affinity and disrupts IL1α, IL1β, IL33, IL36α, IL36β and IL36γ signaling without inducing ADCC. CAN10 is currently undergoing preclinical development in preparation for clinical studies.

The efficacy of IL1RAP-blockade as an anti-inflammatory treatment was investigated in a mouse model of acute peritonitis (i.p injection of MSU crystals). A CAN10 surrogate (mCAN10) decreased the recruitment of neutrophils and monocytes to the peritoneum as well as the production of e.g IL6 and KC. Blocking only IL1α/β had similar effects but notably, mCAN10 also induced additional anti-inflammatory responses including reductions in e.g IL5 and eotaxin. In addition, mCAN10, but not anti-IL1β, reduced skin inflammation in a mouse model of psoriasis. Taken together, these results indicate that blocking IL1RAP is a potent anti-inflammatory strategy that is qualitatively different from blocking IL1α/β alone.

IL1, IL33 and IL36 may have disease promoting roles in myocarditis, an inflammatory heart disease with no available treatment. Therefore, we investigated if IL1RAP blockade can counteract inflammation and decline in heart function in a model of autoimmune myocarditis (EAM). EAM was induced by immunizing Balb/C mice with αMHC peptide on day 0 and 7. Treatment with mCAN10 or isotype control started day 7 and heart function was analyzed by echocardiography at days 0, 28 and 42. Interestingly, anti-inflammatory treatment with mCAN10 potently counteracted the decline in heart function. These studies highlight the potential of blocking IL1RAP to treat inflammatory diseases.

Structural and Biophysical Characterization of Human EXTL3: Domain Organization, Glycosylation, and Solution Structure

Heparan sulfate proteoglycans are proteins substituted with one or more heparan sulfate (HS) polysaccharides, found in abundance at cell surfaces. HS chains influence the activity of many biologically important molecules involved in cellular communication and signaling. The exostosin (EXT) proteins are glycosyltransferases in the Golgi apparatus that assemble HS chains on HSPGs. The EXTL3 enzyme mainly works as an initiator in HS biosynthesis. In this work, human lumenal N-glycosylated EXTL3 (EXTL3ΔN) was cloned, expressed in human embryonic kidney cells, and purified. Various biophysical and biochemical approaches were then employed to elucidate the N-glycosylation sites and the function of their attached N-glycans. Furthermore, the stability and conformation of the purified EXTL3ΔN protein in solution have been analyzed. Our data show that EXTL3ΔN has N-glycans at least at two positions, Asn290 and Asn592, which seem to be critical for proper protein folding and/or release. EXTL3ΔN is quite stable, as high temperature (∼59 °C) was required for denaturation. Deconvolution of the EXTL3ΔN far-UV CD spectrum revealed a substantial fraction of β sheets (25%) with a minor proportion of α-helices (14%) in the secondary structure. Solution small-angle X-ray scattering and dynamic light scattering revealed an extended structure suggestive of a dimeric arrangement and consisting of two distinct regions, narrow and broad, respectively. This is consistent with bioinformatics analyses suggesting a 3-domain structure with two glycosyltransferase domains and a coiled-coil domain.

Improvements in the order, isotropy and electron density of glypican-1 crystals by controlled dehydration

The use of controlled dehydration for improvement of protein crystal diffraction quality is increasing in popularity, although there are still relatively few documented examples of success. A study has been carried out to establish whether controlled dehydration could be used to improve the anisotropy of crystals of the core protein of the human proteoglycan glypican-1. Crystals were subjected to controlled dehydration using the HC1 device. The optimal protocol for dehydration was developed by careful investigation of the following parameters: dehydration rate, final relative humidity and total incubation time Tinc. Of these, the most important was shown to be Tinc. After dehydration using the optimal protocol the crystals showed significantly reduced anisotropy and improved electron density, allowing the building of previously disordered parts of the structure.