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-1ß, IL-33, IL-36α, IL-36ß, 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.

Combined inhibition of IL-1, IL-33 and IL-36 signalling by targeting IL1RAP ameliorates skin and lung fibrosis in preclinical models of systemic sclerosis.

BACKGROUND: The interleukin (IL)-1 receptor accessory protein (IL1RAP) is an essential coreceptor required for signalling through the IL-1, IL-33 and IL-36 receptors. Here, we investigate the antifibrotic potential of the combined inhibition of these cytokines by an anti-IL1RAP antibody to provide a scientific background for clinical development in systemic sclerosis (SSc). METHODS: The expression of IL1RAP-associated signalling molecules was determined by data mining of publicly available RNA sequencing (RNAseq) data as well as by imaging mass cytometry. The efficacy of therapeutic dosing of anti-IL1RAP antibodies was determined in three complementary mouse models: sclerodermatous chronic graft-versus-host disease (cGvHD), bleomycin-induced dermal fibrosis model and topoisomerase-I (topo)-induced fibrosis. RESULTS: SSc skin showed upregulation of IL1RAP and IL1RAP-related signalling molecules on mRNA and protein level compared with normal skin. IL-1, IL-33 and IL-36 all regulate distinct gene sets related to different pathophysiological processes in SSc. The responses of human fibroblasts and endothelial cells to IL-1, IL-33 and IL-36 were completely blocked by treatment with an anti-IL1RAP antibody in vitro. Moreover, anti-IL1RAP antibody treatment reduced dermal and pulmonary fibrosis in cGvHD-induced, bleomycin-induced and topoisomerase-induced fibrosis. Importantly, RNAseq analyses revealed effects of IL1RAP inhibition on multiple processes related to inflammation and fibrosis that are also deregulated in human SSc skin. CONCLUSION: This study provides the first evidence for the therapeutic benefits of targeting IL1RAP in SSc. Our findings have high translational potential as the anti-IL1RAP antibody CAN10 has recently entered a phase one clinical trial.

Interleukin-1 receptor accessory protein blockade limits the development of atherosclerosis and reduces plaque inflammation.

AIMS: The interleukin-1 receptor accessory protein (IL1RAP) is a co-receptor required for signalling through the IL-1, IL-33, and IL-36 receptors. Using a novel anti-IL1RAP-blocking antibody, we investigated the role of IL1RAP in atherosclerosis. METHODS AND RESULTS: Single-cell RNA sequencing data from human atherosclerotic plaques revealed the expression of IL1RAP and several IL1RAP-related cytokines and receptors, including IL1B and IL33. Histological analysis showed the presence of IL1RAP in both the plaque and adventitia, and flow cytometry of murine atherosclerotic aortas revealed IL1RAP expression on plaque leucocytes, including neutrophils and macrophages. High-cholesterol diet fed apolipoprotein E-deficient (Apoe-/-) mice were treated with a novel non-depleting IL1RAP-blocking antibody or isotype control for the last 6 weeks of diet. IL1RAP blockade in mice resulted in a 20% reduction in subvalvular plaque size and limited the accumulation of neutrophils and monocytes/macrophages in plaques and of T cells in adventitia, compared with control mice. Indicative of reduced plaque inflammation, the expression of several genes related to leucocyte recruitment, including Cxcl1 and Cxcl2, was reduced in brachiocephalic arteries of anti-IL1RAP-treated mice, and the expression of these chemokines in human plaques was mainly restricted to CD68+ myeloid cells. Furthermore, in vitro studies demonstrated that IL-1, IL-33, and IL-36 induced CXCL1 release from both macrophages and fibroblasts, which could be mitigated by IL1RAP blockade. CONCLUSION: Limiting IL1RAP-dependent cytokine signalling pathways in atherosclerotic mice reduces plaque burden and plaque inflammation, potentially by limiting plaque chemokine production.

Blockade of IL-1α and IL-1ß signaling by the anti-IL1RAP antibody nadunolimab (CAN04) mediates synergistic anti-tumor efficacy with chemotherapy.

IL-1α and IL-1ß are both involved in several aspects of tumor biology, including tumor initiation, progression, metastasis, and not least in resistance to various therapies. IL-1α can function as an alarmin to signal cellular stress, and acts to induce downstream events, including production of IL-1ß, to amplify the signal. Both IL-1α and IL-1ß act through the same receptor complex, IL-1R1-IL1RAP, to mediate signal transduction. IL1RAP is expressed on tumor cells and in the tumor microenvironment by for example CAF, macrophages and endothelial cells. The anti-IL1RAP antibody nadunolimab (CAN04) inhibits both IL-1α and IL-1ß signaling and induces ADCC of IL1RAP-expressing tumor cells. As both IL-1α and IL-1ß mediate chemoresistance, the aim of this study was to explore the potential synergy between nadunolimab and chemotherapy. This was performed using the NSCLC PDX model LU2503 and the syngeneic MC38 model, in addition to in vitro cell line experiments. We show that chemotherapy induces expression and release of IL-1α from tumor cells and production of IL-1ß-converting enzyme, ICE, in the tumor stroma. IL-1α is also demonstrated to act on stromal cells to further induce the secretion of IL-1ß, an effect disrupted by nadunolimab. Nadunolimab, and its surrogate antibody, synergize with platinum-based as well as non-platinum-based chemotherapy to induce potent anti-tumor effects, while blockade of only IL-1ß signaling by anti-IL-1ß antibody does not achieve this effect. In conclusion, blockade of IL1RAP with nadunolimab reduces IL-1-induced chemoresistance of tumors.

Apolipoprotein A-I primes beta cells to increase glucose stimulated insulin secretion.

The increase of plasma levels of high-density lipoproteins and Apolipoprotein A-I (ApoA-I), its main protein component, has been shown to have a positive action on glucose disposal in type 2 diabetic patients. The current study investigates the unexplored function of ApoA-I to prime beta cells for improved insulin secretion. INS-1E rat clonal beta cells as well as isolated murine islets were used to study the effect of ApoA-I on responsiveness of the beta cells to high glucose challenge. Confocal and transmission electron microscopy were used to dissect ApoA-I mechanisms of action. Chemical endocytosis blockers were used to understand the role of ApoA-I internalization in mediating its positive effect. Pre-incubation of beta cells and isolated murine islets with ApoA-I augmented glucose stimulated insulin secretion. This effect appeared to be due to an increased reservoir of insulin granules at the cell membrane, as confirmed by confocal and transmission electron microscopy. Moreover, ApoA-I induced pancreatic and duodenal homeobox 1 (PDX1) shuttling from the cytoplasm to the nucleus, with the subsequent increase in the proinsulin processing enzyme protein convertase 1 (PC1/3). Finally, the blockade of ApoA-I endocytosis in beta cells resulted in a loss of ApoA-I positive action on insulin secretion. The proposed mechanisms of the phenomenon here described include ApoA-I internalization into beta cells, PDX1 nuclear translocation, and increased levels of proinsulin processing enzymes. Altogether, these events lead to an increased number of insulin granules.

Lack of Ability to Present Antigens on Major Histocompatibility Complex Class II Molecules Aggravates Atherosclerosis in ApoE-/- Mice.

BACKGROUND: Hypercholesterolemic mice lacking factors required for activation of CD4+ T cells are characterized by reduced development of atherosclerosis. Consequently, it has been assumed that atherosclerosis involves loss of tolerance against modified self-antigens generated in response to hypercholesterolemia and that presentation of such antigens on major histocompatibility complex class II (MHCII) leads to activation of proatherogenic Th1 cells. In this study, we wanted to determine the role of antigen presentation on MHCII in atherosclerosis development. METHODS: Apolipoprotein E (ApoE-/-) mice deficient for MHCII (ApoE-/-MHCII-/-) were used to study the role of MHCII in atherosclerosis development. RESULTS: Compared with ApoE-/- mice, ApoE-/-MHCII-/- mice had reduced levels of CD4+ T cells, immunoglobulin G and M levels, and Th1 and Th2 cytokines in plasma. CD8+ T cells were increased and regulatory T cells were reduced both in spleen and in lesions of ApoE-/-MHCII-/- mice. Decreased plasma levels of inflammatory cytokines in ApoE-/-MHCII-/- mice indicated reduced systemic inflammation. Despite this, ApoE-/-MHCII-/- mice had significantly more atherosclerosis as assessed by en face Oil Red O staining of the aorta (4.7±2.9% versus 1.9±1.3%; P<0.01) and cross-sectional area of subvalvular lesions (7.7±2.2×105 µm2 versus 4.6±2.8×105 µm2; P<0.05). Cell transfer and blocking antibody studies suggested that loss of regulatory T cells is the most important cause of aggravated atherosclerosis in ApoE-/-MHCII-/- mice. CONCLUSIONS: Our observations demonstrate that antigen presentation on MHCII has important protective functions in atherosclerosis and that this is primarily the result of activation of regulatory T cells. These findings have implications for understanding the possible risks and benefits of immunosuppressive therapy in patients with cardiovascular disease.

ApoAI-derived peptide increases glucose tolerance and prevents formation of atherosclerosis in mice.

AIMS/HYPOTHESIS: Finding new treatment alternatives for individuals with diabetes with severe insulin resistance is highly desired. To identify novel mechanisms that improve glucose uptake in skeletal muscle, independently from insulin levels and signalling, we have explored the therapeutic potential of a short peptide sequence, RG54, derived from apolipoprotein A-I (ApoA-I). METHODS: INS-1E rat clonal beta cells, C2C12 rat muscle myotubes and J774 mouse macrophages were used to study the impact of RG54 peptide on glucose-stimulated insulin secretion, glucose uptake and cholesterol efflux, respectively. GTTs were carried out on diet-induced insulin-resistant and Leprdb diabetic mouse models treated with RG54 peptide, and the impact of RG54 peptide on atherosclerosis was evaluated in Apoe-/- mice. Control mice received ApoA-I protein, liraglutide or NaCl. RESULTS: The synthetic RG54 peptide induced glucose uptake in cultured muscle myotubes by a similar amount as insulin, and also primed pancreatic beta cells for improved glucose-stimulated insulin secretion. The findings were verified in diet-induced insulin-resistant and Leprdb diabetic mice, jointly confirming the physiological effect. The RG54 peptide also efficiently catalysed cholesterol efflux from macrophages and prevented the formation of atherosclerotic plaques in Apoe-/- mice. CONCLUSIONS/INTERPRETATION: The RG54 peptide exhibits good prospects for providing glucose control and reducing the risk of cardiovascular disease in individuals with severe insulin resistance.

Recent advances on CD4+ T cells in atherosclerosis and its implications for therapy.

Atherosclerosis is an arterial inflammatory disease and the primary cause of cardiovascular disease. T helper (Th) cells are an important part in atherosclerotic plaque as they can be either disease promoting or protective. A body of evidence points to a pro-atherosclerotic role of Th1 cells, whereas the role of Th2, Th17 and iNKT cells seems more complex and dependent on surrounding factors, including the developmental stage of the disease. Opposed to Th1 cells, there is convincing support for an anti-atherogenic role of Tregs. Recent data identify the plasticity of Th cells as an important challenge in understanding the functional role of different Th cell subsets in atherosclerosis. Much of the knowledge of Th cell function in atherosclerosis is based on findings from experimental models and translating this into human disease is challenging. Targeting Th cells and/or their specific cytokines represents an attractive option for future therapy against atherosclerosis, although the benefits and the risk of modulation of Th cells with these novel drug targets must first be carefully assessed.

Endarterectomy patients with elevated levels of circulating IL-16 have fewer cardiovascular events during follow-up.

BACKGROUND AND PURPOSE: Increased interleukin 16 (IL-16) levels in carotid plaques have been associated with reduced incidence of cardiovascular (CV) events during follow-up in patients who underwent carotid endarterectomy (CEA). In the present study we aimed to determine whether high circulating levels of IL-16 also are associated with a decreased risk of CV events after CEA. METHODS: Patients, who had their carotid plaques surgically removed (n=473), were followed for a mean follow-up time of 3.1years. Plasma levels of IL-16 the day before surgery were analyzed by proximity extension assay (PEA) and associated with the occurrence of CV events during follow-up (n=98). RESULTS: High levels of circulating IL-16 were independently associated with a decreased risk of CV events when comparing the highest versus the lowest IL-16 tertile (hazard ratio [HR] 0.47; 95% CI 0.27-0.81; P=0.007), as well as with CV deaths (HR 0.25; 95% CI 0.09-0.70; P=0.008). CONCLUSION: These present findings indicate an association between IL-16 and less clinical complications of atherosclerosis in a population with known advanced carotid disease.

Apolipoprotein B-100 Antibody Interaction With Atherosclerotic Plaque Inflammation and Repair Processes.

BACKGROUND AND PURPOSE: Treatment with IgG against the malondialdehyde (MDA)-modified apolipoprotein B-100 epitope p45 reduces atherosclerosis in experimental models. This study investigated the association between p45 IgG autoantibodies and plaque inflammation in subjects with advanced cardiovascular disease. METHODS: Native and MDA-p45 IgG levels were analyzed by ELISA in 349 carotid endarterectomy patients. In a subcohort of 195 subjects, endarterectomy samples were analyzed by immunohistochemistry and ELISA to determine plaque constituents and inflammation. Peripheral blood mononuclear cells were isolated from healthy donors. RESULTS: Patients with preoperative events of neurological ischemia had lower levels of native p45 IgG. Low levels of MDA-p45 IgG were associated with increased risk of postoperative cardiovascular death during a mean follow-up of 54 months. High plasma levels of native p45 IgG were associated with increased plaque content of collagen and smooth muscle cell growth factors, as well as with lower levels of proinflammatory cytokines. Exposure of peripheral blood mononuclear cells from healthy donors to recombinant MDA-p45 IgG in presence of oxidized low-density lipoprotein reduced the expression of tumor necrosis factor-α and stimulated release of smooth muscle cell growth factors. CONCLUSIONS: This study confirms previous experimental findings of anti-inflammatory properties of apolipoprotein B-100 p45 antibodies and provides the first clinical evidence of associations between p45 IgG autoantibody levels and atherosclerotic plaque inflammation, plaque repair as well as prevalent and incident cardiovascular events in carotid endarterectomy patients. These findings suggest the possibility that treatment with anti-p45 antibodies may have beneficial effects in advanced cardiovascular disease.

Human Carotid Plaques With High Levels of Interleukin-16 Are Associated With Reduced Risk for Cardiovascular Events.

BACKGROUND AND PURPOSE: Interleukin-16 (IL-16) functions as a regulator of T-cell growth and acts as an inducer of cell migration. The aim of this study was to determine whether IL-16 measured in human carotid plaques was associated with symptoms (eg, stroke, transient ischemic attack, or amaurosis fugax), markers of plaque stability, and postoperative cardiovascular events. METHODS: Plaques obtained from patients who had ≥1 cerebrovascular ischemic events within 1 month before endarterectomy (n=111) were compared with plaques from patients without symptoms (n=95). Neutral lipids, smooth muscle cell, and macrophage contents were evaluated histologically, and collagen, elastin, and caspase-3 activity were measured biochemically. IL-16, matrix metalloproteinases, and tissue inhibitors of metalloproteinases were measured in plaque homogenates using a multiplex immunoassay. IL-16, CD3, CD4, and FoxP3 mRNA expressions in carotid plaques were analyzed with quantitative real-time polymerase chain reaction. RESULTS: Carotid plaques from asymptomatic patients had higher levels of IL-16 mRNA. High plaque IL-16 protein levels (above median) were associated with reduced incidence of postoperative cardiovascular events during a mean follow-up of 21 months (hazard ratio, 0.47; 95% confidence interval, 0.22-0.99; P=0.047). IL-16 levels correlated with the plaque-stabilizing components: elastin, collagen, matrix metalloproteinase-2, tissue inhibitors of metalloproteinase-1, tissue inhibitors of metalloproteinase-2 and FoxP3 mRNA. CONCLUSIONS: This study shows that high levels of IL-16 are associated with asymptomatic carotid plaques, expression of factors contributing to plaque stability, and decreased risk of new cardiovascular events during a 2-year period after surgery, suggesting that IL-16 might have a protective role in human atherosclerotic disease.

Soluble urokinase plasminogen activator receptor is associated with inflammation in the vulnerable human atherosclerotic plaque.

BACKGROUND AND PURPOSE: Recently, plasma soluble urokinase plasminogen activator receptor (suPAR) has gained interest as a marker of cardiovascular risk. suPAR is released through the cleavage of urokinase plasminogen activator receptor (uPAR), which is found in monocytes, activated T-lymphocytes and endothelial cells, all involved in atherosclerosis. suPAR levels have been well studied in plasma, but no studies have focused on suPAR in human atherosclerotic plaques. The aim of this study was to determine whether suPAR measured in the plaque is associated with symptomatic plaques and plaque inflammation. METHODS: Plasma and carotid plaques from 162 patients were analyzed. Lipids, collagen, uPAR, and macrophages were measured histologically. Cytokines and suPAR were measured in homogenized plaque extracts using multiplex immunoassay and ELISA, respectively. Plasma levels of suPAR were analysed with ELISA. CD3, CD4, as well as uPAR mRNA expression were assessed with quantitative real-time polymerase chain reaction in plaque homogenates from 123 patients. RESULTS: Plaque and plasma suPAR levels were higher in symptomatic patients compared with asymptomatic patients. Plaque suPAR levels correlated with plaque content of lipids and macrophages and with proinflammatory chemokines and cytokines monocyte chemoattractant protein 1, tumor necrosis factor α, interleukin 1ß, interleukin 6, platelet-derived growth factor AB/BB, monocyte inflammatory protein 1ß, regulated on activation normal T-cell expressed and secreted, and s-CD40L. uPAR mRNA and histological staining for uPAR correlated with plaque content of suPAR. CONCLUSIONS: This study shows that suPAR in human carotid plaques and plasma is associated with the presence of symptoms and that plaque suPAR is associated with the vulnerable inflammatory plaque. These findings strengthen the hypothesis of suPAR as a future marker of vulnerable atherosclerotic plaques.