Altered Receptor Research Articles

Alzheimer’s Disease risk gene SORL1 affects synaptic function in hiPSC‐derived cortical neurons

AbstractBackgroundThe cellular endo‐lysosomal network (ELN) is implicated in Alzheimer’s Disease pathology and Sortilin‐related receptor 1 (SORL1) is important for normal function of the neuronal ELN. Loss of SORL1 in human induced pluripotent stem cell (hiPSC) derived neurons replicates early AD cytopathology, such as enlarged early endosomes. Work in our laboratory has shown that SORL1 deficiency results in decreased cell‐surface expression of glutamate receptor subunit GLUR1 and neurotrophic receptor TRKB. RNAseq of SORL1 deficient neurons revealed alterations in synaptic‐associated gene ontology transcripts. Together, these data implicate a potential functional consequence for SORL1 deletion. Here we investigate the impact of SORL1 on hiPSC‐derived neuronal synaptic function.MethodNeuronal cultures were differentiated using dual SMAD inhibition of previously generated wild‐type and SORL1 deficient hiPSCs. Following differentiation, neuronal cultures were either purified using cell surface markers CD44, CD184, and CD271 or passaged as mixed cultures for immunocytochemical (ICC) or electrophysiological experiments, respectively. For ICC, neurons were then fixed with paraformaldehyde and stained with experiment‐appropriate antibodies before imaging on a confocal scanning microscope. Mixed cultures were plated onto Axion Biosystems multiple electrode array (MEA) culture plates for electrophysiological analysis. MEA cultures were recorded twice a week for up to ten weeks post‐plating. Recordings and analysis were performed using Axion Biosystems Maestro Pro system.ResultUsing ICC, we find alterations in alterations in synaptic protein and glutamate receptor co‐localization in SORL1 deficient neuronal cultures. When cultured on MEA plates, wild‐type and SORL1 deficient neuronal cultures are active and robust. Neuronal cultures develop glutamate signaling dependent patterns of activity, or network bursting. Neural firing rates are increased in SORL1 deficient neurons. Network bursting properties in SORL1 deficient are altered in comparison to wild‐type cultures, consistent with increased neural excitability.ConclusionLoss of SORL1 alters hiPSC‐derived neuronal activity and synapse‐dependent activity. Further investigation is warranted into the alterations in neuronal physiology and will help us understand the role AD‐related ELN disruption plays in synaptic pathologies.

Potential use of the S-protein-Angiotensin converting enzyme 2 binding pathway in the treatment of coronavirus disease 2019.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the pathogen that causes coronavirus disease 2019 (COVID-19), infects humans through a strong interaction between the viral spike protein (S-protein) and angiotensin converting enzyme 2 (ACE2) receptors on the cell surface. The infection of host lung cells by SARS-CoV-2 leads to clinical symptoms in patients. However, ACE2 expression is not restricted to the lungs; altered receptors have been found in the nasal and oral mucosa, vessel, brain, pancreas, gastrointestinal tract, kidney, and heart. The future of COVID-19 is uncertain, however, new viral variants are likely to emerge. The SARS-CoV-2 Omicron variant has a total of 50 gene mutations compared with the original virus; 15 of which occur in the receptor binding domain (RBD). The RBD of the viral S-protein binds to the human ACE2 receptor for viral entry. Mutations of the ACE2-RBD interface enhance tight binding by increasing hydrogen bond interactions and expanding the accessible surface area. Extracorporeal membrane oxygenation, hyperbaric oxygen, and aggressive dialysis for the treatment of COVID-19 have shown various degrees of clinical success. The use of decoy receptors based on the ACE2 receptor as a broadly potent neutralizer of SARS-CoV-2 variants has potential as a therapeutic mechanism. Drugs such as 3E8 could block binding of the S1-subunit to ACE2 and restrict the infection of ACE2-expressing cells by a variety of coronaviruses. Here, we discuss the development of ACE2-targeted strategies for the treatment and prevention of COVID-19.

Immune phenotypes that are associated with subsequent COVID-19 severity inferred from post-recovery samples

Severe COVID-19 causes profound immune perturbations, but pre-infection immune signatures contributing to severe COVID-19 remain unknown. Genome-wide association studies (GWAS) identified strong associations between severe disease and several chemokine receptors and molecules from the type I interferon pathway. Here, we define immune signatures associated with severe COVID-19 using high-dimensional flow cytometry. We measure the cells of the peripheral immune system from individuals who recovered from mild, moderate, severe or critical COVID-19 and focused only on those immune signatures returning to steady-state. Individuals that suffered from severe COVID-19 show reduced frequencies of T cell, mucosal-associated invariant T cell (MAIT) and dendritic cell (DC) subsets and altered chemokine receptor expression on several subsets, such as reduced levels of CCR1 and CCR2 on monocyte subsets. Furthermore, we find reduced frequencies of type I interferon-producing plasmacytoid DCs and altered IFNAR2 expression on several myeloid cells in individuals recovered from severe COVID-19. Thus, these data identify potential immune mechanisms contributing to severe COVID-19.

Hypersensitivity reactions to small molecule drugs.

Drug hypersensitivity reactions induced by small molecule drugs encompass a broad spectrum of adverse drug reactions with heterogeneous clinical presentations and mechanisms. These reactions are classified into allergic drug hypersensitivity reactions and non-allergic drug hypersensitivity reactions. At present, the hapten theory, pharmacological interaction with immune receptors (p-i) concept, altered peptide repertoire model, and altered T-cell receptor (TCR) repertoire model have been proposed to explain how small molecule drugs or their metabolites induce allergic drug hypersensitivity reactions. Meanwhile, direct activation of mast cells, provoking the complement system, stimulating or inhibiting inflammatory reaction-related enzymes, accumulating bradykinin, and/or triggering vascular hyperpermeability are considered as the main factors causing non-allergic drug hypersensitivity reactions. To date, many investigations have been performed to explore the underlying mechanisms involved in drug hypersensitivity reactions and to search for predictive and preventive methods in both clinical and non-clinical trials. However, validated methods for predicting and diagnosing hypersensitivity reactions to small molecule drugs and deeper insight into the relevant underlying mechanisms are still limited.

Abstract 12554: Hipsc Derived Cardiomyocytes for Mechanistic, Patient Tailored Treatment in a Novel Mutation Linked to Cpvt

Background: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a disease related to altered ryanodine receptor (RyR) mediated SR Ca 2+ leak and associated with sudden cardiac death in young adults. We recently identified a family with a mixed phenotype of CPVT and long-QT-syndrome (CPVT3*) related to a novel mutation in the trans-2.3-enyol-CoA reductase-like (TECRL) gene. Ventricular arrhythmia burden varies greatly between individual CPVT3* patients. Methods/Results: We generated human induced pluripotent stem cell derived cardiomyocytes (iPSc-CM) from a control and CPVT3* patient to explore underlying mechanisms and individualize pharmacological treatment. iPSc-CM were studied using confocal Ca 2+ imaging (fluo-4). Ca 2+ signaling during excitation-contraction coupling was studied in the presence of different clinically available modulators of RyR mediated SR Ca 2+ leak. In particular, cardiomyocyte function and arrythmias were tested upon addition of the class Ic antiarrhythmic flecainide (10μM), the RyR stabilizer dantrolene (1μM), the betablocker R-Carvedilol (1μM), the kinase inhibitor Rimacalib (10μM) and the RyR-Calstabin interaction stabilizer S107 (10μM). Under baseline conditions, CPVT3* iPSc-CM showed significantly decreased Ca 2+ transient (CaT) amplitudes and increased CaT duration. Upon addition of the beta-agonist isoproterenol (ISO, 100nM), CaT amplitudes and pro-arrhythmogenic Ca 2+ release (i.e. Ca 2+ sparks) significantly increased in CPVT3* as compared to control. All pharmaceuticals altered Ca 2+ signaling in CPVT3* in a substance dependent manner and pro-arrhythmogenic Ca 2+ release was particularly mitigated upon addition of flecainide. Treatment of the CPVT3* patient with flecainide significantly reduced ventricular premature beats as determined by 24 hour holter-ECG monitoring. Conclusion: We quantitatively assessed drugs targeting RyR mediated SR Ca 2+ leak in a CPVT3* patient with a novel TECRL mutation using iPSc-CM. Favorable in-vitro results of flecainide were mirrored in a significant reduction of ventricular arrhythmia in-vivo. Our results underscore the potential of iPSc-CM for the development of patient-tailored treatment in genetic arrhythmia syndromes.

Role of progesterone on dexamethasone-induced alterations in placental vascularization and progesterone receptors in rats†.

Intrauterine growth restriction (IUGR) is manifested by lower maternal progesterone levels, smaller placental size, and decreased placental vascularity indicated by lower expression of vascular endothelial growth factor (VEGF). Studies showed that progesterone increases angiogenesis and induces VEGF expression in different tissues. Therefore, the aim of the present study is to evaluate the effect of progesterone on placental vascular bed and VEGF expression and the modulation of nuclear and membranous progesterone receptors (PR) in dexamethasone-induced rat IUGR model. Pregnant Sprague-Dawley rats were allocated into four groups and given intraperitoneal injections of either saline, dexamethasone, dexamethasone, and progesterone or progesterone. Injections started on gestation day (DG) 15 and lasted until the days of euthanization (19 and 21 DG). Enzyme-linked immunosorbent assay was used to evaluate plasma progesterone levels. Real-time PCR and western blotting were used to evaluate gene and protein expressions of VEGF, and PR in labyrinth and basal placental zones. Immunohistochemistry was used to locate VEGF and different PRs in placental cells. Immunofluorescence was used to monitor the expression of blood vessel marker (αSMA). Dexamethasone decreased the vascular bed fraction and the expression of VEGF in both placental zones. Progesterone co-treatment with dexamethasone prevented this reduction. Nuclear and membrane PRs showed tissue-specific expression in different placental zones and responded differently to both dexamethasone and progesterone. Progesterone treatment improves the outcomes in IUGR pregnancy. Progesterone alleviated DEX-induced IUGR probably by promoting placental VEGF and angiogenesis.

More than one-third of advanced non-small-cell lung cancer patients do not receive immunochemotherapy due to intolerance.

Combination therapy with immune checkpoint inhibitors (ICIs) and chemotherapy (ICI + chemotherapy) has become the standard first line treatment for driver oncogene-negative advanced non-small-cell lung cancer (NSCLC). However, it may be more toxic compared to monotherapy, which limits its use. Moreover, the feasibility of the combination therapy in clinical practice remains unknown. We conducted a cohort study to determine the implementation rate of ICI + chemotherapy in clinical practice. We retrospectively reviewed clinical data from advanced NSCLC patients who received systemic therapy at 13 institutions between December 2018 and December 2020. After excluding 154 patients with epidermal growth factor receptor (EGFR) or anaplastic lymphoma kinase (ALK) gene alterations, a total of 919 NSCLC patients were included. Among them, 442 were treated with ICI + chemotherapy (48%), whereas 477 were treated with other therapies (52%). Among these 477 patients, 340 did not receive ICI + chemotherapy because of intolerance (71%); thus, more than one-third of the advanced NSCLC patients do not benefit from the combination therapy due to intolerance. Among the 659 NSCLC patients for whom PD-L1 was < 50% or unknown, only 342 received the ICI + chemotherapy combination (52%) even though it is considered preferable to either therapy alone; the remaining 318 patients were treated with other therapies (48%). Among the 318 patients who did not receive ICI + chemotherapy, 274 were intolerant to it (86%). Our results revealed that a substantial proportion of advanced NSCLC patients did not benefit from ICI + chemotherapy due to intolerance. As treatments for NSCLC are moving toward combinations for greater efficacy, their feasibility in clinical practice must be taken into consideration.

Molecular Insights into Epigenetics and Cannabinoid Receptors.

The actions of cannabis are mediated by G protein-coupled receptors that are part of an endogenous cannabinoid system (ECS). ECS consists of the naturally occurring ligands N-arachidonylethanolamine (anandamide) and 2-arachidonoylglycerol (2-AG), their biosynthetic and degradative enzymes, and the CB1 and CB2 cannabinoid receptors. Epigenetics are heritable changes that affect gene expression without changing the DNA sequence, transducing external stimuli in stable alterations of the DNA or chromatin structure. Cannabinoid receptors are crucial candidates for exploring their functions through epigenetic approaches due to their significant roles in health and diseases. Epigenetic changes usually promote alterations in the expression of genes and proteins that can be evaluated by various transcriptomic and proteomic analyses. Despite the exponential growth of new evidence on the critical functions of cannabinoid receptors, much is still unknown regarding the contribution of various genetic and epigenetic factors that regulate cannabinoid receptor gene expression. Recent studies have identified several immediate and long-lasting epigenetic changes, such as DNA methylation, DNA-associated histone proteins, and RNA regulatory networks, in cannabinoid receptor function. Thus, they can offer solutions to many cellular, molecular, and behavioral impairments found after modulation of cannabinoid receptor activities. In this review, we discuss the significant research advances in different epigenetic factors contributing to the regulation of cannabinoid receptors and their functions under both physiological and pathological conditions. Increasing our understanding of the epigenetics of cannabinoid receptors will significantly advance our knowledge and could lead to the identification of novel therapeutic targets and innovative treatment strategies for diseases associated with altered cannabinoid receptor functions.

Genetic Variant in Nicotinic Receptor α4-Subunit Causes Sleep-Related Hyperkinetic Epilepsy via Increased Channel Opening.

We describe genetic and molecular-level functional alterations in the α4β2 neuronal nicotinic acetylcholine receptor (nAChR) from a patient with sleep-related hyperkinetic epilepsy and a family history of epilepsy. Genetic sequencing revealed a heterozygous variant c.851C>G in the CHRNA4 gene encoding the α4 subunit, resulting in the missense mutation p.Ser284Trp. Patch clamp recordings from genetically engineered nAChRs incorporating the α4-Ser284Trp subunit revealed aberrant channel openings in the absence of agonist and markedly prolonged openings in its presence. Measurements of single channel current amplitude distinguished two pentameric stoichiometries of the variant nAChR containing either two or three copies of the α4-Ser284Trp subunit, each exhibiting aberrant spontaneous and prolonged agonist-elicited channel openings. The α4-Ser284 residue is highly conserved and located within the M2 transmembrane α-helix that lines the ion channel. When mapped onto the receptor’s three-dimensional structure, the larger Trp substitution sterically clashes with the M2 α-helix from the neighboring subunit, promoting expansion of the pore and stabilizing the open relative to the closed conformation of the channel. Together, the clinical, genetic, functional, and structural observations demonstrate that α4-Ser284Trp enhances channel opening, predicting increased membrane excitability and a pathogenic seizure phenotype.

In vitro neutrophil migration is associated with inhaled corticosteroid treatment and serum cytokines in pediatric asthma.

Background: Different asthma phenotypes are driven by molecular endotypes. A Th1-high phenotype is linked to severe, therapy-refractory asthma, subclinical infections and neutrophil inflammation. Previously, we found neutrophil granulocytes (NGs) from asthmatics exhibit decreased chemotaxis towards leukotriene B4 (LTB4), a chemoattractant involved in inflammation response. We hypothesized that this pattern is driven by asthma in general and aggravated in a Th1-high phenotype. Methods: NGs from asthmatic nd healthy children were stimulated with 10 nM LTB4/100 nM N-formylmethionine-leucyl-phenylalanine and neutrophil migration was documented following our prior SiMA (simplified migration assay) workflow, capturing morphologic and dynamic parameters from single-cell tracking in the images. Demographic, clinical and serum cytokine data were determined in the ALLIANCE cohort. Results: A reduced chemotactic response towards LTB4 was confirmed in asthmatic donors regardless of inhaled corticosteroid (ICS) treatment. By contrast, only NGs from ICS-treated asthmatic children migrate similarly to controls with the exception of Th1-high donors, whose NGs presented a reduced and less directed migration towards the chemokines. ICS-treated and Th1-high asthmatic donors present an altered surface receptor profile, which partly correlates with migration. Conclusions: Neutrophil migration in vitro may be affected by ICS-therapy or a Th1-high phenotype. This may be explained by alteration of receptor expression and could be used as a tool to monitor asthma treatment.

1.1 Cell-Type–Specific Distributions of Cannabinoid Receptor 1 in Healthy and Illness States

Alterations in the cannabinoid receptor 1 (CB1) are implicated in the development of psychopathologies. However, prior CB1 studies have shown discrepant results in postmortem brain samples obtained from patients with mental health disorders. These studies largely accounted for CB1 present on inhibitory boutons, yet it is known that CB1 participates in both depolarization-induced suppression of inhibition and excitation. Thus, examining cell type–specific CB1 alterations may offer clarity to prior findings and increase our insight into CB1’s influences on excitatory-inhibitory (E/I) balance in healthy and illness states.

Nanoscale alterations in GABAB receptors and GIRK channel organization on the hippocampus of APP/PS1 mice

Alzheimer’s disease (AD) is characterized by a reorganization of brain activity determining network hyperexcitability and loss of synaptic plasticity. Precisely, a dysfunction in metabotropic GABAB receptor signalling through G protein-gated inwardly rectifying K+ (GIRK or Kir3) channels on the hippocampus has been postulated. Thus, we determined the impact of amyloid-β (Aβ) pathology in GIRK channel density, subcellular distribution, and its association with GABAB receptors in hippocampal CA1 pyramidal neurons from the APP/PS1 mouse model using quantitative SDS-digested freeze-fracture replica labelling (SDS-FRL) and proximity ligation in situ assay (P-LISA). In wild type mice, single SDS-FRL detection revealed a similar dendritic gradient for GIRK1 and GIRK2 in CA1 pyramidal cells, with higher densities in spines, and GIRK3 showed a lower and uniform distribution. Double SDS-FRL showed a co-clustering of GIRK2 and GIRK1 in post- and presynaptic compartments, but not for GIRK2 and GIRK3. Likewise, double GABAB1 and GIRK2 SDS-FRL detection displayed a high degree of co-clustering in nanodomains (40–50 nm) mostly in spines and axon terminals. In APP/PS1 mice, the density of GIRK2 and GIRK1, but not for GIRK3, was significantly reduced along the neuronal surface of CA1 pyramidal cells and in axon terminals contacting them. Importantly, GABAB1 and GIRK2 co-clustering was not present in APP/PS1 mice. Similarly, P-LISA experiments revealed a significant reduction in GABAB1 and GIRK2 interaction on the hippocampus of this animal model. Overall, our results provide compelling evidence showing a significant reduction on the cell surface density of pre- and postsynaptic GIRK1 and GIRK2, but not GIRK3, and a decline in GABAB receptors and GIRK2 channels co-clustering in hippocampal pyramidal neurons from APP/PS1 mice, thus suggesting that a disruption in the GABAB receptor–GIRK channel membrane assembly causes dysregulation in the GABAB signalling via GIRK channels in this AD animal model.

EGFR uncommon alterations in advanced non-small cell lung cancer and structural insights into sensitivity to diverse tyrosine kinase inhibitors.

Background: Approximately 10% of patients with non-small cell lung cancer (NSCLC) harbor uncommon epidermal growth factor receptor (EGFR) alterations. This study aims to investigate the therapeutic responses and predict the binding activity of different tyrosine kinase inhibitors (TKIs) for EGFR uncommon alterations. Methods: Between May 2014 and June 2021, clinical outcomes of NSCLC patients harboring EGFR uncommon alterations who received diverse treatment modalities: first-generation (1G) EGFR-TKI, second-generation (2G) EGFR-TKI afatinib, chemotherapy, and 1G TKI in combination with chemotherapy as the initial therapy were retrospectively analyzed, and structural analysis for the binding activity of major uncommon subtypes G719A, S768I, and L861Q to different TKIs were predicted. Results: A total of 102 NSCLC patients harboring EGFR uncommon alterations with treatment and survival outcomes were included and analyzed. The majority of patients presented compound mutations (54.9%), and G719X plus S768I was the predominant subtype (n = 33, 32.3%). There was a significant difference in median progression-free survival (mPFS) between therapeutic patterns (p = 0.015) and EGFR alteration subtypes (p = 0.017). Rather than almonertinib and furmonertinib, afatinib, dacomitinib and osimertinib revealed favorable binding activity to G719A mutation. In contrast, S768I and L861Q mutation indicated an unaffected binding activity to these diverse kinds of EGFR TKIs. Conclusion: Together with afatinib, 1G-TKIs combined with chemotherapy might be another effective option for NSCLC patients harboring EGFR uncommon alterations. Based on computational findings, afatinib, dacomitinib, and osimertinib might confer favorable activity to G719A, S768I, and L861Q, whereas almonertinib and furmonertinib revealed less activity to G719A.

Tenovin-1 Ameliorates Renal Fibrosis in High-Fat-Diet-Induced Diabetic Nephropathy via Antioxidant and Anti-Inflammatory Pathways.

High-fat diet (HFD)-induced obesity has been involved in the development of diabetic nephropathy (DN). Tenovin-1, a potent selective SIRT1/2 inhibitor, regulates various target proteins. The present study evaluated the protective effect of Tenovin-1 against renal fibrosis in HFD-induced Zucker diabetic fatty (ZDF) rats. Rats were fed a normal chow diet or HFD. Tenovin-1 (45 mg/kg) administered to HFD-fed rats decreased inflammatory cytokine expression in the serum of the rats. The antioxidant status and oxidative damage to lipids or DNA were significantly restored by Tenovin-1. Additionally, Tenovin-1 reduced the levels of blood urea nitrogen (BUN), serum creatinine (sCr), microalbumin, and urinary protein-based biomarkers in the urine of HFD-fed rats. The abnormal architecture of the kidney and pancreas was restored by Tenovin-1 administration. Tenovin-1 also reduced apoptosis in the kidneys of the HFD-fed rats and HG-treated NRK-52E cells. It significantly lowered the levels of ECM proteins in the kidneys of HFD-fed rats and HG-treated NRK-52E cells. Additionally, Tenovin-1 markedly reduced claudin-1, SIRT1, and SIRT2, but increased SIRT3 and SIRT4 in HFD-fed rats and NRK-52E cells treated with HG. Furthermore, Tenovin-1 altered epidermal growth factor receptor (EGFR), platelet-derived growth factor receptor-β (PDGFR-β), and signal transducer and activator of transcription 3 (STAT3) levels in the kidneys of HFD-fed rats. Conclusively, this study shows that Tenovin-1 can be a potential candidate drug for the treatment of HFD-induced renal fibrosis, in vivo and in vitro models.

Assessment of clinical utility and predictive potential of pre-chemotherapy soluble urokinase plasminogen activator receptor: Observational single center study.

Alteration of urokinase plasminogen activator receptor (uPAR) in neoplasms is a prerequisite for invasiveness and metastatic ability. In the present study, we aimed to evaluate the relationship of pre-chemotherapy soluble uPAR (suPAR) with the odds for metastasis, lack of disease control, and its predictive ability for progression-free survival (PFS). Baseline plasma suPAR levels were measured by ELISA in 89 patients with various cancers prior to initiation of systemic treatment. Patients were followed prospectively until metastatic progression or death. TCGA Pan-Cancer dataset was mined for available RNAseq expression data of the PLAUR gene in patients with breast, colon, and lung cancer, and therelevant genomic and clinical data were extracted for further analysis. Pre-chemotherapy suPAR levels were significantly associated with white blood cell counts and fibrinogen and were significantly elevated both in patients with metastatic disease and in patients with progression. Increasing suPAR was significantly associated with odds for progression in the prespecified multivariate analysis (odds ratio 2.47, 95% confidence interval 1.3 - 5.11). In univariate Cox regression, suPAR was predictive of shortened progression-free survival (PFS) (hazard ratio 1.065, 95% confidence interval 1.002 - 1.13; p = 0.041). There was a trend towards shortened PFS in patients with higher baseline suPAR levels (cutoff 8.1 ng/mL). In the TCGA lung cancer cohort, PLAUR mRNA expression was significantly associated with shortened PFS in both univariate and multivariate analyses. High PLAUR gene expression conferred significant survival disadvantage only in patients with colon and lung cancer. SuPAR may bear predictive potential for adverse outcomes in cancer, but its utility as a biomarker seems to be more pronounced in cancers with associated inflammatory state.

Combination of polyglycerol sebacate coated with collagen for vascular engineering

Introduction: Here, we monitored the cytocompatibility of scaffolds consisting of poly (glycerol sebacate) (PGS) coated with collagen (Col) for endothelial cell activity after 72 hours. Methods: Human endothelial cells were allocated into Control, PGS, and PGS+Col groups. Scaffolds were characterized using FTIR and HNMR spectroscopy. Contact angel analysis and SEM were used to study wettability, surface morphology, and cell attachment. Cell survival was assessed using LDH leakage assay. Levels of Tie-1, Tie-2, VE-Cadherin, and VEGFR-2 were measured using western blotting and real-time PCR. Results: FTIR and HNMR analyses revealed the proper blending in PGS+Col group. SEM imaging exhibited a flat surface in the PGS group while thin Col fibers were detected in PGS+Col surface. The addition of Col to the PGS reduced the contract angle values from 97.3˚ to 81.1˚. Compared to PGS substrate alone, in PGS+Col group, cells appropriately attached to the surface. PGS and PGS+Col did not alter the leakage of LDH to the supernatant compared to control cells, showing the cytocopatiblity of PGS-based scaffolds. SOD and NO levels were increased significantly in PGS (p<0.05) and PGS+Col groups (p<0.001), respectively. We found that PGS+Col decreased Tie-1 content in endothelial cells whereas protein levels of Tie-2 and VE-Cadherin and expression of VEGFR-2 remained unchanged compared to PGS and control groups. Conclusion: Simultaneous application of Col and PGS can stimulate normal endothleial cell morphology without the alteration of tyrosine kinases receptors and cadherin.

Decreased Platelet Specific Receptor Expression of P-Selectin and GPIIb/IIIa Predict Future Non-Surgical Bleeding in Patients after Left Ventricular Assist Device Implantation.

Non-surgical bleeding (NSB) is one of the major clinical complications in patients under continuous-flow left ventricular assist device (LVAD) support. The increased shear stress leads to an altered platelet receptor composition. Whether these changes increase the risk for NSB is unclear. Thus, we compared the platelet receptor composition of patients with (bleeder group, n = 18) and without NSB (non-bleeder group, n = 18) prior to LVAD implantation. Blood samples were obtained prior to LVAD implantation and after bleeding complications in the post-implant period. Platelet receptor expression of GPIbα, GPIIb/IIIa, P-selectin and CD63 as well as intra-platelet oxidative stress levels were quantified by flow cytometry. Bleeders and non-bleeders were comparable regarding clinical characteristics, von Willebrand factor diagnostics and the aggregation capacity before and after LVAD implantation (p > 0.05). LVAD patients in the bleeder group suffered from gastrointestinal bleeding (33%; n = 6), epistaxis (22%; n = 4), hematuria or hematoma (17%; n = 3, respectively) and cerebral bleeding (11%; n = 2). Prior to LVAD implantation, a restricted surface expression of the platelet receptors P-selectin and GPIIb/IIIa was observed in the bleeder group (P-selectin: 7.2 ± 2.6%; GPIIb/IIIa: 26,900 ± 13,608 U) compared to non-bleeders (P-selectin: 12.4 ± 8.1%, p = 0.02; GPIIb/IIIa: 36,259 ± 9914 U; p = 0.02). We hypothesized that the reduced platelet receptor expression of P-selectin and GPIIb/IIIa prior to LVAD implantation may be linked to LVAD-related NSB.

Different modes of synaptic and extrasynaptic NMDA receptor alteration in the hippocampus of P301S tau transgenic mice.

N-methyl-d-aspartate receptors (NMDARs) are pivotal players in the synaptic transmission and synaptic plasticity underlying learning and memory. Accordingly, dysfunction of NMDARs has been implicated in the pathophysiology of Alzheimer disease (AD). Here, we used histoblot and sodium dodecylsulphate-digested freeze-fracture replica labelling (SDS-FRL) techniques to investigate the expression and subcellular localisation of GluN1, the obligatory subunit of NMDARs, in the hippocampus of P301S mice. Histoblots showed that GluN1 expression was significantly reduced in the hippocampus of P301S mice in a laminar-specific manner at 10 months of age but was unaltered at 3 months. Using the SDS-FRL technique, excitatory synapses and extrasynaptic sites on spines of pyramidal cells and interneuron dendrites were analysed throughout all dendritic layers in the CA1 field. Our ultrastructural approach revealed a high density of GluN1 in synaptic sites and a substantially lower density at extrasynaptic sites. Labelling density for GluN1 in excitatory synapses established on spines was significantly reduced in P301S mice, compared with age-matched wild-type mice, in the stratum oriens (so), stratum radiatum (sr) and stratum lacunosum-moleculare (slm). Density for synaptic GluN1 on interneuron dendrites was significantly reduced in P301S mice in the so and sr but unaltered in the slm. Labelling density for GluN1 at extrasynaptic sites showed no significant differences in pyramidal cells, and only increased density in the interneuron dendrites of the sr. This differential alteration of synaptic versus extrasynaptic NMDARs supports the notion that the progressive accumulation of phospho-tau is associated with changes in NMDARs, in the absence of amyloid-β pathology, and may be involved in the mechanisms causing abnormal network activity of the hippocampal circuit.

351P Prevalence of ERBB alterations in colorectal cancer patients using genomic profiling

In colorectal cancer (CRC) resistance to EGFR inhibitors such as cetuximab or panitumumab can involve activating alterations in human epidermal growth factor receptor 2 (ERBB2/HER2). Anti-ERBB2 therapy is indicated in ERBB2-amplified CRC that is RAS and BRAF wild type. ERBB3/4 alterations can also activate HER2 signaling and thus be effective therapy targets. Our study investigates the prevalence of ERBB alterations in patients with CRC, as well as their importance for treatment. The tumor-normal pairing based OncomapTM ExTra assay was employed to sequence CRC samples by whole-exome DNA sequencing to detect single base substitutions, indels, copy number alterations, and structural variants, and calculate tumor mutational burden (TMB) and microsatellite instability (MSI). Clinically actionable alterations, defined as associated with FDA-approved drugs or clinical trial enrollment, were identified. BRAF mutations, and RAS (KRAS, NRAS, HRAS) and ERBB (ERBB2/3/4) amplification or gain-of-function missense mutations were summarized. Of 757 CRC patients assayed, 38 ERBB alterations were found in 37 (4.9%) patients; 32% of the alterations were not in ERBB2 (26 ERBB2, 11 ERBB3, 1 ERBB4). Of the 38 ERBB alterations, 16 (42%) were ERBB2 amplifications and the rest were gain-of-function missense mutations capable of activating the ERBB2 signaling pathway; 1 patient had alterations in two ERBB genes. There were 56 (7.4%) BRAF mutant samples and 375 (49.5%) RAS mutant samples (348 KRAS, 27 NRAS, 0 HRAS), which included 5 (1.3%) KRAS amplifications. Of the 37 patients with an ERBB alteration, 22 (59%) had no RAS or BRAF alteration (17 ERBB2, 3 ERBB3, 1 ERBB4, 1 ERBB2 ERBB3) identifying a subset in which anti-ERBB2 therapy is likely to respond. Further, 15 (39%) had a RAS but no BRAF alteration (8 ERBB2, 7 ERBB3), which may be targeted by a combination of anti-ERBB2 and MEK inhibitors. Presence of both a BRAF and ERBB mutation, which may be targeted by anti-ERBB2 and RAF/MEK inhibitors, was not observed. The results of whole-exome genomic profiling of CRC samples highlight that combinations of gene alterations are critical in the management of CRC and guidance towards appropriate clinical trials.

100P Co-mutational landscape of key fibroblast growth factor receptor (FGFR) alterations in intra-hepatic cholangiocarcinoma (iCCA), bladder cancer (BC) and glioma

Selective tyrosine kinase inhibitors targeting FGFR1–4 genomic alterations (GAs) are in development or have been granted FDA-accelerated approval for FGFR-altered cancers (i.e. advanced iCCA and BC). Understanding FGFR inhibitor resistance mechanisms is increasingly relevant; the genomic co-mutational landscape influencing inhibitor response should be studied comprehensively.