Soluble Decoy Receptor Research Articles

Soluble TGF-β decoy receptor TGFBR3 exacerbates Alzheimer's disease pathology by modifying microglial function.

Alzheimer's disease (AD) is a major cause of progressive dementia characterized by memory loss and progressive neurocognitive dysfunction. However, the molecular mechanisms are not fully understood. To elucidate the molecular mechanism contributing to AD, an integrated analytical workflow was deployed to identify pivotal regulatory target within the RNA-sequencing (RNA-seq) data of the temporal cortex from AD patients. Soluble transforming growth factor beta receptor 3 (sTGFBR3) was identified as a critical target in AD, which was abnormally elevated in AD patients and AD mouse models. We then demonstrated that sTGFBR3 deficiency restored spatial learning and memory deficits in amyloid precursor protein (APP)/PS1 and streptozotocin (STZ)-induced neuronal impairment mice after its expression was disrupted by a lentiviral (LV) vector expressing shRNA. Mechanistically, sTGFBR3 deficiency augments TGF-β signaling and suppressing the NF-κB pathway, thereby reduced the number of disease-associated microglia (DAMs), inhibited proinflammatory activity and increased the phagocytic activity of DAMs. Moreover, sTGFBR3 deficiency significantly mitigated acute neuroinflammation provoked by lipopolysaccharide (LPS) and alleviated neuronal dysfunction induced by STZ. Collectively, these results position sTGFBR3 as a promising candidate for therapeutic intervention in AD.

Osteoprotegerin (OPG) and its ligands RANKL and TRAIL in falciparum, vivax and knowlesi malaria: correlations with disease severity, and B cell production of OPG.

Osteoprotegerin (OPG) is a soluble decoy receptor for receptor activator of NF-ƙB ligand (RANKL) and TNF-related apoptosis-inducing ligand (TRAIL), and is increasingly recognised as a marker of poor prognosis in a number of diseases. Here we demonstrate that in Malaysian adults with falciparum and vivax malaria, OPG is increased, and its ligands TRAIL and RANKL decreased, in proportion to disease severity. In volunteers experimentally infected with P. falciparum and P. vivax, RANKL was suppressed, while TRAIL was unexpectedly increased, suggesting binding of OPG to RANKL prior to TRAIL. We also demonstrate that P. falciparum stimulates B cells to produce OPG in vitro, and that B cell OPG production is increased ex vivo in patients with falciparum, vivax and knowlesi malaria. Our findings provide further evidence of the importance of the OPG/RANKL/TRAIL pathway in pathogenesis of diseases involving systemic inflammation, and may have implications for adjunctive therapies. Further evaluation of the role of B cell production of OPG in host responses to malaria and other inflammatory diseases is warranted.

Modulation of the pharmacokinetics of soluble ACE2 decoy receptors through glycosylation

The Spike of SARS-CoV-2 recognizes a transmembrane protease, angiotensin-converting enzyme 2 (ACE2), on host cells to initiate infection. Soluble derivatives of ACE2, in which Spike affinity is enhanced and the protein is fused to Fc of an immunoglobulin, are potent decoy receptors that reduce disease in animal models of COVID-19. Mutations were introduced into an ACE2 decoy receptor, including adding custom N-glycosylation sites and a cavity-filling substitution together with Fc modifications, which increased the decoy's catalytic activity and provided small to moderate enhancements of pharmacokinetics following intravenous and subcutaneous administration in humanized FcRn mice. Most prominently, sialylation of native glycans increases exposures by orders of magnitude, and the optimized decoy is therapeutically efficacious in a mouse COVID-19 model. Ultimately, an engineered and highly sialylated decoy receptor produced using methods suitable for manufacture of representative drug substance has high exposure with a 5- to 9-day half-life. Finally, peptide epitopes at mutated sites in the decoys generally have low binding to common HLA class II alleles and the predicted immunogenicity risk is low. Overall, glycosylation is a critical molecular attribute of ACE2 decoy receptors and modifications that combine tighter blocking of Spike with enhanced pharmacokinetics elevate this class of molecules as viable drug candidates.

Decoy receptors as biomarkers for exploring aetiology and designing new therapies.

Soluble decoy receptors (DR) are circulating proteins that act as molecular traps for ligands that modulate various signalling pathways. These proteins can be exploited as biomarkers and, in some cases, as drugs in various disease contexts. Inflammation is a key area where DRs have shown significant potential. By binding to pro-inflammatory cytokines, inflammatory DRs, such as soluble tumour necrosis factor receptors (sTNFRs), can inhibit downstream inflammatory signalling. This modulation of the inflammatory response holds promise for therapeutic interventions in various inflammatory conditions, including cardiovascular and chronic kidney diseases. Soluble DRs for advanced glycation end products (sRAGE) bind to advanced glycation end products (AGEs), reducing their detrimental effects on vascular function and atherosclerosis. High circulating sRAGE levels are associated with a lower risk for CV events, highlighting the potential of these soluble receptors for assessing the role of AGEs in CV diseases and managing the attendant risk. DRs may serve as biomarkers and therapeutic agents to advance our understanding of disease mechanisms and improve patients' outcomes. Their ability to modulate signalling pathways in a controlled manner opens up new opportunities for therapeutic interventions in various diseases, ranging from inflammation to cardiovascular and renal disorders.

Serum levels of soluble receptor activator for nuclear factor kB ligand play a crucial role in the association of osteoprotegerin with coronary artery disease.

Osteoprotegerin (OPG) is a soluble decoy receptor for receptor activator of nuclear factor kB ligand (RANKL), and is implicated in the pathogenesis of atherosclerosis. The aim of the present study was to examine the hypothesis that serum OPG concentrations are increased in patients with stable coronary artery disease (CAD) at different serum levels of soluble RANKL (sRANKL). The study used a case-control design in which consecutively hospitalized individuals were recruited. Fasting blood samples were taken upon admission for serum testing. Participants with previously diagnosed CAD that was asymptomatic or had controlled symptoms constituted the stable CAD group, whereas patients with negative coronary computed tomography angiography results constituted the control non-CAD group. Exclusion criteria included recent acute coronary syndrome, severe heart failure, CAD-complicating autoimmune, blood or thyroid diseases, cancer, elevated temperature with or without infection, severe liver or kidney dysfunction, abnormal calcium metabolism, recent surgery and trauma history. A total of 118 individuals were included in the study. Smoothed plots generated using the recursive method and multivariate models showed that the incidence of stable CAD increased with serum OPG level up to the turning point of 18 pg/ml. This trend was observed at both high [odds ratio (OR), 1.61; 95% confidence interval (CI), 1.04-2.50; P=0.032) and low sRANKL concentrations (OR, 1.52; 95% CI, 1.06-2.17; P=0.022) after adjustment for cardiovascular risk factors. In conclusion, serum OPG levels ≤18 pg/ml are positively associated with stable CAD, regardless of sRANKL levels. In addition, at the same serum OPG level, higher sRANKL levels are associated with a greater incidence of stable CAD compared with lower sRANKL levels. This study identified the relationship between OPG, sRANKL, and stable CAD, and established the reference range for future clinical use.

Development of a mutant aerosolized ACE2 that neutralizes SARS-CoV-2 in vivo.

The rapid evolution of SARS-CoV-2 variants poses a challenge for immune recognition and antibody therapies. However, the virus is constrained by the requirement that it recognizes a human host receptor protein. A recombinant ACE2 could protect against SARS-CoV-2 infection by functioning as a soluble decoy receptor. We designed a mutant version of ACE2 with impaired catalytic activity to enable the purification of the protein using a single affinity purification step. This protein can be nebulized and retains the ability to bind the relevant domains from SARS-CoV-1 and SARS-CoV-2. Moreover, this protein inhibits viral infection against a panel of coronaviruses in cells. Finally, we developed an aerosolized delivery system for animal studies and show the modified ACE2 offers protection in an animal model of COVID-19. These results show proof-of-concept for an aerosolized delivery method to evaluate anti-SARS-CoV-2 agents in vivo and suggest a new tool in the ongoing fight against SARS-CoV-2.

Inhibition of activin receptor 2 signalling ameliorates metabolic dysfunction–associated steatotic liver disease in western diet/L-NAME induced cardiometabolic disease

ObjectiveBlockade of activin 2 receptor (ACVR2) signaling has been shown to improve insulin sensitivity and aid in weight loss. Inhibition of ACVR2 signaling restores cardiac function in multiple heart failure models. However, its potential in the treatment of obesity-related cardiometabolic disease remains unknown. Here, we investigated targeting ACVR2 signaling in cardiometabolic disease manifested with metabolic dysfunction–associated steatotic liver disease (MASLD). MethodsMice were fed a high-fat, high-sugar diet combined with the administration of nitric oxide synthase inhibitor L-NAME in drinking water, which causes hypertensive stress. For the last eight weeks, the mice were treated with the soluble ACVR2B decoy receptor (sACVR2B-Fc). ResultssACVR2B-Fc protected against the development of comorbidities associated with cardiometabolic disease. This was most pronounced in the liver where ACVR2 blockade attenuated the development of MASLD including cessation of pro-fibrotic activation. It also significantly reduced total plasma cholesterol levels, impeded brown adipose tissue whitening, and improved cardiac diastolic function. In vitro, ACVR2 ligands activin A, activin B and GDF11 induced profibrotic signaling and the proliferation of human cardiac fibroblasts. ConclusionsBlockade of ACVR2B exerts broad beneficial effects for therapy of cardiometabolic disease. By reducing obesity, ameliorating cardiovascular deterioration and restraining MASLD, blockade of ACVR2B signaling proves a potential target in MASLD and its comorbidities.

DHT and Insulin Upregulate Secretion of the Soluble Decoy Receptor of IL-33 From Decidualized Endometrial Stromal Cells.

Interleukin 33 (IL-33) signaling regulates most of the key processes of pregnancy, including decidualization, trophoblast proliferation and invasion, vascular remodeling, and placental growth. Accordingly, dysregulation of IL-33, its membrane-bound receptor (ST2L, transducer of IL-33 signaling), and its soluble decoy receptor (sST2, inhibitor of IL-33 signaling) has been linked to a wide range of adverse pregnancy outcomes that are common in women with obesity and polycystic ovary syndrome, that is, conditions associated with hyperandrogenism, insulin resistance, and compensatory hyperinsulinemia. To reveal if androgens and insulin might modulate uteroplacental IL-33 signaling, we investigated the effect of dihydrotestosterone (DHT) and/or insulin on the expression of ST2L and sST2 (along with the activity of their promoter regions), IL-33 and sIL1RAP (heterodimerization partner of sST2), during in vitro decidualization of endometrial stromal cells from 9 healthy women. DHT and insulin markedly upregulated sST2 secretion, in addition to the upregulation of its messenger RNA (mRNA) expression, while the proximal ST2 promoter, from which the sST2 transcript originates, was upregulated by insulin, and in a synergistic manner by DHT and insulin combination treatment. On the other hand, sIL1RAP was slightly downregulated by insulin and IL-33 mRNA expression was not affected by any of the hormones, while ST2L mRNA expression and transcription from its promoter region (distal ST2 promoter) could not be detected or showed a negligibly low level. We hypothesize that high levels of androgens and insulin might lead to subfertility and pregnancy complications, at least partially, through the sST2-dependent downregulation of uteroplacental IL-33 signaling.

Adipocyte Glucocorticoid Receptor Activation With High Glucocorticoid Doses Impairs Healthy Adipose Tissue Expansion by Repressing Angiogenesis.

In Human, glucocorticoids (GC) are commonly prescribed because of their anti-inflammatory and immunosuppressive properties. However, high doses of GC often lead to adverse side effects including diabetes and lipodystrophy. We recently reported that adipocyte glucocorticoid receptor (GR)-deficient (AdipoGR-KO) mice under corticosterone (CORT) treatment exhibited a massive adipose tissue (AT) expansion associated with a paradoxical improvement of metabolic health compared to control mice. However, whether GR may control adipose development remains unclear. Here, we show a specific induction of the hypoxiainducible factor HIF-1α and the pro-angiogenic Vascular Endothelial Growth Factor-A expression in GR-deficient adipocytes of AdipoGR-KO mice as compared to control mice, together with an increased adipose vascular network, as assessed by 3D-analysis imaging. GR activation reduced HIF-1α recruitment on Vegfa promoter resulting from Hif-1α downregulation at the transcriptional and post-translational levels. Importantly, in CORT-treated AdipoGR-KO mice, the blockade of VEGFA by a soluble decoy receptor prevented AT expansion and the healthy metabolic phenotype. Finally, in subcutaneous AT from Cushing patients, higher VEGFA expression was associated with a better metabolic profile. Collectively, these results highlight that adipocyte GR negatively controls AT expansion and metabolic health through the down-regulation of the major angiogenic effector VEGFA and inhibiting vascular network development. (LIPOCUSH, NCT01688349).

Activation of the Interleukin-18 Signaling Pathway via Direct Receptor Dimerization in the Absence of Interleukin-18.

Interleukin 18 (IL-18) is a key cytokine involved in the activation of T and NK cells, which are major effector cells in tumor killing. However, recombinant IL-18 showed limited efficacy in clinical trials. A recent study showed the lack of efficacy was largely due to the existence of IL-18BP, a soluble decoy receptor for IL-18. It was shown that engineered IL-18 variants that maintained pathway activation, but avoided IL-18BP binding, could exert potent antitumor effects. In this study, we demonstrated an alternative strategy to activate IL-18 signaling through direct receptor dimerization. These results provide evidences that the IL-18 pathway can be activated by directly bridging the receptors and, therefore, bypassing the IL-18BP-mediated inhibition.

Development of Anti-OSCAR Antibodies for the Treatment of Osteoarthritis.

Osteoarthritis (OA) is the most common joint disease that causes local inflammation and pain, significantly reducing the quality of life and normal social activities of patients. Currently, there are no disease-modifying OA drugs (DMOADs) available, and treatment relies on pain relief agents or arthroplasty. To address this significant unmet medical need, we aimed to develop monoclonal antibodies that can block the osteoclast-associated receptor (OSCAR). Our recent study has revealed the importance of OSCAR in OA pathogenesis as a novel catabolic regulator that induces chondrocyte apoptosis and accelerates articular cartilage destruction. It was also shown that blocking OSCAR with a soluble OSCAR decoy receptor ameliorated OA in animal models. In this study, OSCAR-neutralizing monoclonal antibodies were isolated and optimized by phage display. These antibodies bind to and directly neutralize OSCAR, unlike the decoy receptor, which binds to the ubiquitously expressed collagen and may result in reduced efficacy or deleterious off-target effects. The DMOAD potential of the anti-OSCAR antibodies was assessed with in vitro cell-based assays and an in vivo OA model. The results demonstrated that the anti-OSCAR antibodies significantly reduced cartilage destruction and other OA signs, such as subchondral bone plate sclerosis and loss of hyaline cartilage. Hence, blocking OSCAR with a monoclonal antibody could be a promising treatment strategy for OA.

Effects of different doses of exercise in adjunct to diet-induced weight loss on the AGE-RAGE axis in patients with short standing type 2 diabetes: Secondary analysis of the DOSE-EX multi-arm, parallel-group, randomised trial

Aims/hypothesisThese secondary analyses aimed to investigate the effects of different volumes of exercise in adjunct to diet-induced weight loss and standard care on advanced glycation end-products (AGEs) and receptor for AGE (RAGE). We hypothesized that exercise in adjunct to a diet-induced weight loss would dose-dependently increase the soluble decoy receptor for AGE (sRAGE) more than diet-induced weight loss and standard care alone. Secondarily, we expected changes in sRAGE to be associated with improved glycaemic control and inversely associated with low-grade inflammation. MethodsThe DOSE-EX study was a 16-week parallel-group, 4-arm, single-centre, assessor-blinded, randomised, controlled trial (NCT03769883). We included persons living with T2D, duration ≤7 years, BMI >27 kg/m2 and <40 kg/m2, without severe diabetic complications. Participants were randomised (1:1:1:1) to either 1) standard care as control (CON), 2) standard care + diet (DCON), 3) standard care + diet + moderate exercise dose (MED) or 4) standard care + diet + high exercise dose (HED). Standard care included algorithm-guided pharmacological treatment. The diet intervention aimed at 25% reduced energy intake. The supervised exercise sessions included two aerobic sessions + one combined (aerobic and resistance training) session per week for the MED group, and four aerobic sessions + two combined sessions per week for the HED group. Primary outcome was the change in sRAGE from baseline to 16-week follow-up. Secondary outcomes encompassed changes in advanced glycation endproducts (AGE), glycaemic control and markers of low-grade inflammation. ResultsA total of 80 participants (CON: n = 20, DCON: n = 19, MED: n = 20, HED: n = 21) were included in this secondary analysis. The mean age was 58.3 years (SD 9.9), 53% males, and median T2D duration was 4.1 years (IQR 2.0–5.5). No change in sRAGE was observed in any of the groups from baseline to follow-up (p > 0.05). Conclusion/interpretationA 16-week intervention with either three or six exercise sessions per week in adjunct to diet-induced weight loss did not change the levels of sRAGE in persons living with well-regulated, short standing T2D.

Unique Immune Blood Markers Between Severe Dengue and Sepsis in Children.

Pediatric dengue and sepsis share clinical and pathophysiologic aspects. Multiple inflammatory and regulatory cytokines, decoy receptors and vascular permeability factors have been implicated in the pathogenesis of both diseases. The differential pattern and dynamic of these soluble factors, and the relationship with clinical severity between pediatric dengue and sepsis could offer new diagnosis and therapeutic strategies. We evaluated the concentration levels of 11 soluble factors with proinflammatory, regulatory and vascular permeability involvement, in plasma from children with dengue or sepsis, both clinically ranging from mild to severe, in the early, late and convalescence phases of the disease. During early acute infection, children with sepsis exhibited specific higher concentration levels of IL-6, vascular endothelial growth factor (VEGF), and its soluble decoy receptor II (sVEGFR2) and lower concentration levels of IL-10 and the soluble tumor necrosis factor receptor 2 (sTNFR2), in comparison with children with severe dengue. In addition, the circulating amounts of soluble ST2, and VEGF/sVEGFR2 were widely associated with clinical and laboratory indicators of dengue severity, whereas secondary dengue virus infections were characterized by an enhanced cytokine response, relative to primary infections. In severe forms of dengue, or sepsis, the kinetics and the cytokines response during the late and convalescence phases of the disease also differentiate. Dengue virus infection and septic processes in children are characterized by cytokine responses of a specific magnitude, pattern and kinetics, which are implicated in the pathophysiology and clinical outcome of these diseases.

Establishment of a TNFRSF11B knock-out human induced pluripotent stem cell line (KSCBi002-B-2) via CRISPR/Cas9 system

A TNFRSF11B (TNF Receptor Superfamily Member 11b) gene encodes a soluble decoy receptor, osteoprotegerin (OPG), which has a key role in repressing osteoclast differentiation. In this report, we generated a biallelic knock-out hiPSC line for the TNFRSF11B gene via CRISPR/Cas9. When TNFRSF11B Knock-out hiPSCs were differentiated into mesenchymal progenitor cells (MPCs), the expression level of OPG was significantly decreased compared to normal hiPSC-derived MPCs. This knock-out hiPSCs will provide a chance to study Paget disease of bone 5 (juvenile Paget disease).

Chronic Trypanosoma cruzi infection activates the TWEAK/Fn14 axis in cardiac myocytes and fibroblasts driving structural and functional changes that affect the heart.

Sustained interaction between the cytokine tumor necrosis factor-like weak inducer of apoptosis (TWEAK) and its functional receptor, fibroblast growth factor-inducible 14 (Fn14), has been linked to cardiovascular disorders. Chagas cardiomyopathy, elicited by Trypanosoma cruzi infection, is associated with chronic inflammation, fibrosis and hypertrophy. This study aimed to explore the involvement of the TWEAK/Fn 14 axis in development of Chagas heart disease. Parasite infection in vitro triggered Fn14 overexpression in atrial HL-1 myocytes and cardiac MCF fibroblasts. Fn14 levels were also increased in heart tissue from C57BL/6 mice at 130 days post-infection, particularly in myocytes and fibroblasts. Concurrently, TWEAK expression in circulating monocytes from this group was higher than that determined in uninfected controls. TWEAK/Fn14 interaction was functional in myocytes and fibroblasts isolated from infected hearts, leading to TNF receptor-associated factor 2 (TRAF2)-mediated activation of nuclear factor kappa B (NFκB) signaling. Ex vivo stimulation of both cell types with recombinant TWEAK for 24h boosted the NFκB-regulated production of proinflammatory/profibrotic mediators (IL-1β, IL-6, TNF-α, IL-8, CCL2, CCL5, MMP-2, MMP-9, ICAM-1, E-selectin) involved in chronic T. cruzi cardiomyopathy. We further evaluated the therapeutic potential of the soluble decoy receptor Fn14-Fc to interfere with TWEAK/Fn14-dependent pathogenic activity. Fn14-Fc treatment of chronically infected mice was effective in neutralizing the ligand and reverting electrocardiographic abnormalities, maladaptive inflammation, adverse remodeling and hypertrophy in myocardium. Altogether, these findings suggest that sustained TWEAK/Fn14 induction by persistent T. cruzi infection is implicated in cardiopathogenesis and make TWEAK/Fn14 axis a promising target for the treatment of chronic Chagas heart disease.

Abstract 1830: E7386, a selective inhibitor of the interaction between β-catenin and CREB-binding protein (CBP), in combination with lenvatinib (LEN), exerts antitumor activity in preclinical tumor models with prior immune checkpoint inhibitor (ICI)-based combination treatment

Abstract Introduction: Combination anti-CTLA-4 antibody (Ab) + anti-PD-1 Ab is approved in multiple cancer types and has improved clinical outcomes. In addition, atezolizumab + bevacizumab combination therapy is approved for unresectable hepatocellular carcinoma. Given the rapid changes in the therapeutic landscape, it is important to investigate effective treatments for people with prior ICI-based combination therapy. E7386 modulates Wnt/β-catenin signaling, and a phase 1 study in combination with LEN (a receptor tyrosine kinase inhibitor that mainly targets both VEGFR and FGFR), in people with solid tumors (NCT04008797) is ongoing. In this study, we examined the antitumor activity of the combination of E7386 + LEN, with either prior anti-CTLA-4 Ab + anti-PD-1 Ab or anti-PD-1 Ab + aflibercept (a soluble decoy receptor against VEGF), in the mouse lung tumor KLN 205 model. Methods: Antitumor activity of E7386 (25 or 50 mg/kg), LEN (3 mg/kg), and the combination, was evaluated in the KLN 205 model (orally, once daily x 14 days), with or without prior treatments of either anti-CTLA-4 Ab (0.2 mg/head, weekly x 3, intraperitoneally [ip]) + anti-PD-1 Ab (0.2 mg/head, weekly x 3, ip)─ie, CTLA-4 + PD-1; or aflibercept (5 mg/kg) + anti-PD-1 Ab (0.2 mg/head, twice a week x 2, ip)─ie, AFL + PD-1. Mice with relatively rapid-growing tumors and prior treatments were given E7386, LEN, and their combination. RNA-seq analyses were conducted by using tumor tissues collected from mice one day after the prior treatment period or without treatment to analyze gene-expression alterations with prior treatments. Results: In the mouse model without prior treatments, LEN had clear antitumor activity. E7386 had limited antitumor activity as a monotreatment. E7386 + LEN had superior antitumor activity vs LEN in a dose-dependent manner. In addition, E7386 + LEN had superior antitumor activity to each single treatment despite either prior CTLA-4 + PD-1 or AFL + PD-1. E7386 + LEN with prior CTLA-4 + PD-1 had equivalent antitumor activity to LEN without prior treatments. Conversely, E7386 + LEN with prior AFL + PD-1 had strong antitumor activity, including marked tumor regression, compared to both LEN alone and E7386 + LEN without prior treatments. RNA-seq analyses showed that intratumoral Axin2, a target gene in the canonical Wnt-signaling pathway, was upregulated with prior AFL + PD-1—suggesting a potential activation of the Wnt-signaling pathway. Conclusion: E7386 + LEN combination shows antitumor activity in the mouse KLN 205 lung tumor model when there is prior ICI-based (CTLA-4 + PD-1 or AFL + PD-1) combination treatment. Further, E7386 + LEN shows enhanced antitumor activity with prior AFL + PD-1; possibly due to activation of Wnt-signaling pathway during prior treatments. Citation Format: Satoshi Kawano, Yusuke Adachi, Megumi Kuronishi, Kohta Toshimitsu, Kotaro Kodama, Takayuki Kimura, Masahiko Kume, Jialing Shen, Saori Watanabe Miyano, Akira Yokoi, Junji Matsui, Yu Kato, Yasuhiro Funahashi. E7386, a selective inhibitor of the interaction between β-catenin and CREB-binding protein (CBP), in combination with lenvatinib (LEN), exerts antitumor activity in preclinical tumor models with prior immune checkpoint inhibitor (ICI)-based combination treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1830.

Plasma Soluble ST2 Levels Are Higher in Neurodegenerative Disorders and Associated with Poorer Cognition.

Suppressor of tumorgenicity 2 (ST2) is highly expressed in brain tissue and is a receptor for interleukin 33 (IL-33). ST2 exists in two forms, a transmembrane receptor (ST2L) and a soluble decoy receptor (sST2). IL-33 binds to ST2L, triggering downstream signaling pathways involved in amyloid plaque clearance. Conversely, sST2 binds competitively to IL-33, attenuating its neuroprotective effects. High sST2 levels have been reported in mild cognitive impairment (MCI) and Alzheimer's disease (AD), suggesting that the IL-33/ST2 signaling pathway may be implicated in neurodegenerative diseases. To investigate plasma sST2 levels in controls and patients with MCI, AD, frontotemporal dementia (FTD), and Parkinson's disease (PD). Plasma sST2 levels were measured using ELISA in 397 subjects (91 HC, 46 MCI, 38 AD, 28 FTD, and 194 PD). Cerebrospinal fluid (CSF) levels of sST2 were measured in 22 subjects. Relationship between sST2 and clinical outcomes were analyzed. Plasma sST2 levels were increased across all disease groups compared to controls, with highest levels seen in FTD followed by AD and PD. Dementia patients with higher sST2 had lower cross-sectional cognitive scores in Frontal Assessment Battery and Digit Span Backward. At baseline, PD-MCI patients had higher sST2, associated with worse attention. In the longitudinal PD cohort, higher sST2 significantly associated with decline in global cognition and visuospatial domains. Plasma sST2 levels correlated with CSF sST2 levels. Plasma sST2 is raised across neurodegenerative diseases and is associated with poorer cognition. Higher baseline sST2 is a potential biomarker of disease severity in neurodegeneration.

Inhibition of activin-signalling reduces the growth of LβT2 gonadotroph pituitary tumours in mouse.

Pituitary tumours are benign neoplasms that derive from hormone-producing cells of the pituitary gland. While medical treatments have emerged for most subtypes, Gonadotroph tumours that express FSH, and/or LH still lack therapeutic options apart from surgery and radiotherapy. Activin-ligands are physiological regulators of production and secretion of FSH by gonadotroph cells, but their role in gonadotroph tumorigenesis remains little explored. Using the LT2 mouse gonadotroph-cell line which produces FSH under Activin-stimulation, we first tested whether sub-cutaneous xenografts of LT2 cells resulted in tumour formation in Rag2KO mice. Histological analysis confirmed the presence of LT2-tumours with endothelial cells and macrophages in their microenvironment. FSH expression was found in a subset of clusters of LT2 cells in the tumours. We subsequently addressed the consequences of targeting activin-signalling via injection of a soluble activin decoy receptor (sActRIIB-Fc). sActRIIB-Fc treatment resulted in significantly decreased LT2 tumour volume. Reduced Smad2-phosphorylation as well as inhibition of tumour-induced FSH production confirmed the efficient targeting of activin-downstream signalling in treated tumours. More interestingly, treated tumours showed significantly fewer endothelial cells, associated with reduced Vegfa expression. In-vitro treatment of LT2 cells with sActRIIB-Fc had no effect on cell proliferation or apoptosis, but Vegfa expression was inhibited, pointing to a likely paracrine effect of LT2 cells on endothelial cells through activin-mediated Vegfa regulation. Further in-vitro and in-vivo studies are now needed to pinpoint the exact roles of activin-signalling in these processes prior to translating these observations to the clinic.

PS-BPB01-7: ANGIOTENSIN II INDUCES AORTIC RUPTURE AND DISSECTION IN OSTEOPROTEGERIN-DEFICIENT MICE

Background: The biological mechanism of action for osteoprotegerin (OPG), a soluble decoy receptor for the receptor activator of nuclear factor kappa-B ligand (RANKL) in the vascular structure, has not been elucidated. The study aim was to determine if OPG affects aortic structural integrity in angiotensin II-induced hypertension. Methods and Results: Mortality was higher (P &lt; 0.0001 by Log-rank test) in 8-week-old male homozygotes of OPG gene knockout (OPG -/- mice given subcutaneous administration of angiotensin II (1,000 ng/kg/min) for 28 days, with an incidence of 21% fatal aortic rupture (Chi-square, 8.024, P = 0.005), and 23% aortic dissection (Chi-square, 4.285, P = 0.038), than in age-matched wild type mice. The absence of OPG was associated with decreased medial and adventitial thickness and increased numbers of elastin breaks as well as with 2.5-fold increased periostin expression and soluble RANKL concentrations. PEGylated human recombinant OPG administration decreased all-causes mortality (-22%, P &lt; 0.001 by Log-rank test), the incidence of fatal aortic rupture (-13%, P = 0.08), and aortic dissection (-23%, P &lt; 0.001) with decreasing numbers of elastin breaks (P = 0.0539) at the supra-renal aorta, periostin expressions (P = 0.0011), and soluble RANKL concentrations (P = 0.0012) in angiotensin II-infused OPG-/- mice. Conclusions: These data suggest that OPG protects against aortic rupture and dissection in Ang II-induced hypertension by inhibiting RANKL activity and periostin expression.

Modern trends in anti-VEGF therapy for age-related macular degeneration

Age-related macular degeneration (AMD) develops in people aged 50 years and older, its pathogenesis involves progressive destruction of the retinal pigment epithelium and Bruch's membrane. There are eight currently known anti-VEGF drugs for treating the neovascular form of AMD, four of them have already been registered and are used in clinical practice. The first registered drug was pegaptanib, which selectively blocks VEGF165. Subsequently, a molecule with a similar mechanism of action was developed and named ranibizumab, which is a humanized monoclonal Fab fragment; it was specifically designed for ophthalmology. Its advantage over pegaptanib was neutralization of all active VEGF-A isoforms. Aflibercept and conbercept are recombinant fusion proteins that act as soluble decoy receptors for VEGF family proteins. Phase III data from the VIEW 1 and 2 studies showed that intraocular injections (IVI) of aflibercept every 1 or 2 months for a year resulted in comparable functional outcomes to monthly IVI of ranibizumab for one year. The next molecule for anti-VEGF therapy that showed effectiveness was brolucizumab - a single-chain fragment of a humanized antibody that binds with high affinity to various VEGF-A isoforms. Simultaneously with studying brolucizumab, another study was conducted involving Abicipar pegol, but that drug showed a high rate of complications. The latest drug registered for the treatment of neovascular AMD is faricimab. The molecule of this drug is a humanized immunoglobulin G antibody that acts on two key points of angiogenesis: VEGF-A and angiopoietin-2 (Ang-2). Thus, the strategy for advancing anti-VEGF therapy lies in the development of molecules with greater efficiency (better effect on newly formed vessels leading to resorption of exudate in the retina, under the neuroepithelium and under the retinal pigment epithelium), which allows not just to preserve vision, but to also significantly improve it when there is no macular atrophy.