FRI0014 A PUTATIVE ROLE OF IGF-1R ON THE PATHOGENESIS OF GOUT THROUGH BINDING TO TRANSCRIPTION FACTORS

Background:

Recent studies showed that SNPs on IGF-1/IGF-1R were highly associated with hyperuricemia and gout [1,2]. It was shown that the IGF-1/IGF-1R signaling pathway played a role in regulating the serum urate level. By modulating the uric acid transporters, IGF-1/IGF-1R influenced the resorption and secretion of uric acid. However, we demonstrated that the increased activation of IGF1R could activate the mTOR pathway, leading to a higher inflammatory response upon pathogen stimulation [3]. This finding indicates that IGF-1/IGF1-R has a role in inflammation, which could results in gout. The IGF-1/IGF-1R pathway may have an overall influence on both urate transporters and inflammatory pathways. it was shown that IGF-1R was not only expressed on the cell surface, but could also internalize into the nucleus and recruit RNA polymerase, regulating the expression of other transcription factors[4]. These transcription factors have been shown to regulate inflammation and have been predicted to bind promoter regions of urate transporters [5]

Objectives:

To unveil how the IGF-1/IGF1-R associates with hyperuricemia and gout by studying the IGF-1R SNP rs6598541.

Methods:

To assess the influence of the SNP to IGF1-R, the protein expression of IGF-1R on the cell surface was identified by flow cytometry in different genotypes. Additionally, we measured the in vitro immune response of PBMCs with different genotypes upon exposure to MSU and/or LPS. To estimate the overall influence of the SNP on the immune response, we analyzed the SNP’s function on transcription factors.

Results:

We observed an enhanced inflammatory response in the homozygous genotype with the risk alleles upon LPS and/or MSU stimulation, indicative of a higher risk for gout. However, the IGF-1R surface expression level was comparable between different genotypes. Furthermore, in epigenetic analysis, we found that rs6598541 located in an enhancer region, which is bound by c-FOS, c-JUN and other transcription factors. In recent years, c-FOS and c-JUN have been shown to regulate inflammatory responses.

Conclusion:

The risk allele of rs6598541 is associated with a higher inflammatory response, which might be the key factor for gout. Because of the location of the SNP, it might explain the function of IGF-1R in gout, and the pathogenesis might be modulated through transcription factors. According to the recent study, intracellular IGF-1R could act as a transcription factor regulating other transcription factors expression, like c-JUN. Additionally, c-JUN has been shown to regulate inflammatory responses. It is tempting to speculate that IGF-1R regulates transcription factors expression and leads to an overall immune responses, which influence the risk of gout.

References:

[1]Kottgen, A., et al.,Genome-wide association analyses identify 18 new loci associated with serum urate concentrations.Nat Genet, 2013.45(2): p. 145-54.

[2]Mannino, G.C., et al.,The polymorphism rs35767 at IGF1 locus is associated with serum urate levels.Sci Rep, 2018.8(1): p. 12255.

[3]Bekkering, S., et al.,Metabolic Induction of Trained Immunity through the Mevalonate Pathway.Cell, 2018.172(1-2): p. 135-146.e9.

[4]Aleksic, T., et al.,Nuclear IGF1R Interacts with Regulatory Regions of Chromatin to Promote RNA Polymerase II Recruitment and Gene Expression Associated with Advanced Tumor Stage.Cancer Res, 2018.78(13): p. 3497-3509.

[5]Granet, C., W. Maslinski, and P. Miossec,Increased AP-1 and NF-kappaB activation and recruitment with the combination of the proinflammatory cytokines IL-1beta, tumor necrosis factor alpha and IL-17 in rheumatoid synoviocytes.Arthritis Res Ther, 2004.6(3): p. R190-8.

Disclosure of Interests:

Ruiqi Liu: None declared, Orsi Gaal: None declared, Viola Klück: None declared, Tania Crisan: None declared, Stephanie Fanucchi: None declared, Musa Mhlanga: None declared, Leo Joosten Consultant of: SAB member of Olatec Therapeutics LLC

AB0930 URATE INDUCED PRIMING OF HUMAN MONOCYTES IS MEDIATED VIA THE TGF-Β PATHWAY

Background:

Hyperuricemia, elevated serum urate levels, is the main risk factor for gout, but is also associated with higher incidence of comorbidities such as cardiovascular disease, type 2 diabetes, metabolic syndrome and chronic kidney disease[1]. Crisanet al.showed that urate leads to increased production of interleukin (IL)-1β, a pro-inflammatory cytokine, and downregulation of IL-1 receptor antagonist (IL-1Ra), the natural inhibitor of IL-1, in human monocytes[2]. This imbalance between IL-1β and IL-1Ra is mediated by epigenetic reprogramming of innate immune cells[2]. RNA sequencing in urate-treated monocytes demonstrated that the TGF-β signalling pathway was differentially expressed[3].

Objectives:

The objective of this study is to further explore the role of TGF-β in urate induced priming of human monocytes.

Methods:

Human peripheral blood mononuclear cells (PBMCs) were isolated from healthy volunteers, adhered to a flat bottom plate, and treated for 24h with a dosing range of urate after which mRNA was isolated. For validation experiments, PBMCs from 9 gout patients and 7 healthy controls were isolated and adhered to a flat bottom plate for 4h after which cells were stored for RNA isolation. qPCR primers designed for TGF-β, TGF-β receptor I and II, MMP9, SMAD7 and ITGAV were used to assess expression levels of TGF-β pathway in these adherent monocytes. For priming experiments, adherent monocytes were primed for 24h with urate and/or recombinant TGF-β1 (R&D systems) with or without a TGF-β receptor II antibody (R&D systems), cells were washed and restimulated with LPS for 24h. Cytokine levels in supernatant were determined by ELISA for IL-1β, IL-6 and IL-1Ra.

Results:

mRNA expression of TGF-β and its downstream targets were upregulated in urate treated monocytes and in gout patients compared to healthy controls. Moreover, urate levels significantly correlated to TGF-β in individuals with gout. Both urate and TGF-β priming increased the release of IL-1β and IL-6 after LPS stimulation in human monocytes. We did not observe a synergistic effect between the two and therefore hypothesized that urate induced inflammation is mediated via TGF-β. Blocking the TGF-β receptor II partly reversed the urate induced phenotype: lowered IL-1β and IL-6 production and restored levels of IL-1Ra. Further validation experiments are ongoing.

Conclusion:

Urate induced priming of human monocytes is at least partly mediated via the TGF-β pathway. This study contributes to the understanding of the pathways involved in urate induced inflammatory status and might in the future provide a mechanistic explanation for the occurrence of some comorbidities in patients with gout. Additionally, as TGF-β is a major player in the pathogenesis of systemic sclerosis, this study might give a rationale for treatment of hyperuricemia in this population.

References:

[1]Bardin, T. and P. Richette,Impact of comorbidities on gout and hyperuricaemia: an update on prevalence and treatment options.BMC Med, 2017.15(1): p. 123.

[2]Crisan, T.O., et al.,Soluble uric acid primes TLR-induced proinflammatory cytokine production by human primary cells via inhibition of IL-1Ra.Ann Rheum Dis, 2016.75(4): p. 755-62.

[3]Crisan, T.O., et al.,Uric acid priming in human monocytes is driven by the AKT-PRAS40 autophagy pathway.Proc Natl Acad Sci U S A, 2017.114(21): p. 5485-5490.

Disclosure of Interests:

Viola Klück: None declared, Linda Mies: None declared, René Bakker: None declared, Tania Crisan: None declared, Leo Joosten Consultant of: SAB member of Olatec Therapeutics LLC

PET and SPECT imaging of a radiolabeled minigastrin analogue conjugated with DOTA, NOTA, and NODAGA and labeled with (64)Cu, (68)Ga, and (111)In

Cholecystokinin-2 (CCK-2) receptors, overexpressed in cancer types such as small cell lung cancers (SCLC) and medullary thyroid carcinomas (MTC), may serve as targets for peptide receptor radionuclide imaging. A variety of CCK and gastrin analogues has been developed, but a major drawback is metabolic instability or high kidney uptake. The minigastrin analogue PP-F11 has previously been shown to be a promising peptide for imaging of CCK-2 receptor positive tumors and was therefore further evaluated. The peptide was conjugated with one of the macrocyclic chelators DOTA, NOTA, or NODAGA. The peptide conjugates were then radiolabeled with either (68)Ga, (64)Cu, or (111)In. All (radio)labeled compounds were evaluated in vitro (IC50) and in vivo (biodistribution and PET/CT and SPECT/CT imaging). IC50 values were in the low nanomolar range for all compounds (0.79-1.51 nM). In the biodistribution studies, (68)Ga- and (111)In-labeled peptides showed higher tumor-to-background ratios than the (64)Cu-labeled compounds. All tested radiolabeled compounds clearly visualized the CCK2 receptor positive tumor in PET or SPECT imaging. The chelator did not seem to affect in vivo behavior of the peptide for (111)In- and (68)Ga-labeled peptides. In contrast, the biodistribution of the (64)Cu-labeled peptides showed high uptake in the liver and in other organs, most likely caused by high blood levels, probably due to dissociation of (64)Cu from the chelator and subsequent transchelation to proteins. Based on the present study, (68)Ga-DOTA-PP-F11 might be a promising radiopharmaceutical for PET/CT imaging of CCK2 receptor expressing tumors such as MTC and SCLC. Clinical studies are warranted to investigate the potential of this tracer.

Obstacles on the way to the clinical visualisation of beta cells: looking for the Aeneas of molecular imaging to navigate between Scylla and Charybdis

For more than a decade, researchers have been trying to develop non-invasive imaging techniques for the in vivo measurement of viable pancreatic beta cells. However, in spite of intense research efforts, only one tracer for positron emission tomography (PET) imaging is currently under clinical evaluation. To many diabetologists it may remain unclear why the imaging world struggles to develop an effective method for non-invasive beta cell imaging (BCI), which could be useful for both research and clinical purposes. Here, we provide a concise overview of the obstacles and challenges encountered on the way to such BCI, in both native and transplanted islets. We discuss the major difficulties posed by the anatomical and cell biological features of pancreatic islets, as well as the chemical and physical limits of the main imaging modalities, with special focus on PET, SPECT and MRI. We conclude by indicating new avenues for future research in the field, based on several remarkable recent results.

Defensive properties of pyrrolizidine alkaloids against microorganisms

The understanding of the selection factors that drive chemical diversification of secondary metabolites of constitutive defence systems in plants, such as pyrrolizidine alkaloids (PAs), is still incomplete. Historically, plants always have been confronted with microorganisms. Long before herbivores existed on this planet, plants had to cope with microbial pathogens. Therefore, plant pathogenic microorganisms may have played an important role in the early evolution of the secondary metabolite diversity. In this review, we discuss the impact that plant-produced PAs have on plant-associated microorganisms. The objective of the review is to present the current knowledge on PAs with respect to anti-microbial activities, adaptation and detoxification by microorganisms, pathogenic fungi, root protection and PA induction. Many in vitro experiments showed effects of PAs on microorganisms. These results point to the potential of microorganisms to be important for the evolution of PAs. However, only a few in vivo studies have been published and support the results of the in vitro studies. In conclusion, the topics pointed out in this review need further exploration by carrying out ecological experiments and field studies.

The genotype dependent presence of pyrrolizidine alkaloids as tertiary amine in Jacobaea vulgaris

Secondary metabolites such as pyrrolizidine alkaloids (PAs) play a crucial part in plant defense. PAs can occur in plants in two forms: tertiary amine (free base) and N-oxide. PA extraction and detection are of great importance for the understanding of the role of PAs as plant defense compounds, as the tertiary PA form is known for its stronger influence on several generalist insects, whereas the N-oxide form is claimed to be less deterrent. We measured PA N-oxides and their reduced tertiary amines by liquid chromatography-tandem mass spectrometry (LC-MS/MS). We show that the occurrence of tertiary PAs is not an artifact of the extraction and detection method. We found up to 50% of tertiary PAs in shoots of Jacobine - chemotype plants of Jacobaea vulgaris. Jacobine and its derivatives (jacoline, jaconine, jacozine and dehydrojaconine) may occur for more than 20% in reduced form in the shoots and more than 10% in the roots. For 22 PAs detected in F(2) hybrids (J. vulgaris × Jacobaea aquatica), we calculate the tertiary amine percentage (TA%=the tertiary amine concentration/(tertiary amine concentration+the corresponding N-oxide concentration) × 100). We found that the TA% for various PAs was genotype-dependent. Furthermore, TA% for the different PAs were correlated and the highest correlations occurred between PAs which share high structural similarity.

Molecular weight fibrinogen variants alter gene expression and functional characteristics of human endothelial cells

BACKGROUND

Fibrin is a temporary matrix that not only seals a wound, but also provides a temporary matrix structure for invading cells during wound healing. Two naturally occurring fibrinogen variants, high molecular weight (HMW) and low molecular weight (LMW) fibrinogen, display different properties in supporting angiogenesis in vivo and in vitro.

OBJECTIVES

This study was aimed at investigating the functional characteristics and molecular mechanisms of human microvascular endothelial cells (HMVECs) cultured on HMW and LMW fibrin matrices.

METHODS AND RESULTS

HMVECs on HMW fibrin matrices showed increased proliferation and tube formation as compared with their counterparts on unfractionated and LMW fibrin. Degradation of HMW fibrin was markedly enhanced by the presence of HMVECs, that of LMW fibrin was enhanced only slightly. However, the expression levels of fibrinolysis-regulating proteins and integrins were similar. Subsequent microarray analysis revealed that the expression of 377 genes differed significantly between HMVECs cultured on HMW fibrin and those cultured on LMW fibrin. Among these genes, UNC5B, DLL4 and the DLL4-Notch downstream targets Hey1, Hey2 and Hes1 showed increased expression in HMVECs on LMW fibrin. However, pharmacologic and genetic (DLL4 small interfering RNA) inhibition of DLL4-Notch signaling blunted rather than enhanced proliferation and tube formation by HMVECs on both fibrin variants.

CONCLUSIONS

Heterogeneity in naturally occurring fibrinogen strongly influences endothelial cell proliferation and tube formation, and causes alterations in gene expression, including that of DLL4-Notch. The higher fibrinolytic sensitivity of HMW fibrin in the presence of HMVECs contributes to increased tube formation. Although the expression of DLL4-Notch was altered, it did not explain the enhanced tube formation in HMW fibrin. This study provides new perspectives for biological and tissue engineering applications.

The analysis of pyrrolizidine alkaloids in Jacobaea vulgaris; a comparison of extraction and detection methods

INTRODUCTION

Pyrrolizidine alkaloids (PAs) serve an important function in plant defence.Objective - To compare different extraction methods and detection techniques, namely gas chromatography with nitrogen phosphorus detection (GC-NPD) and liquid chromatography tandem mass spectrometry (LC-MS/MS) with quadrupole analysers for analysing PAs in Jacobaea vulgaris.

METHODOLOGY

Both formic acid and sulfuric acid were tested for PA extraction from dry plant material. For GC-NPD, reduction is required to transform PA N-oxides into tertiary amines. Zinc and sodium metabisulfite were compared as reducing agents.

RESULTS

The lowest PA concentration measured with GC-NPD was approximately 0.03 mg/g and with LC-MS/MS 0.002 mg/g. The detection of major PAs by both techniques was comparable but a number of minor PAs were not detected by GC-NPD. With the LC-MS/MS procedure higher concentrations were found in plant extracts, indicating that losses may have occurred during the sample preparation for the GC-NPD method. Zinc proved a more effective reducing agent than sodium metabisulfite. The sample preparation for LC-MS/MS analysis using formic acid extraction without any reduction and purification steps is far less complex and less time consuming compared to GC-NPD analysis with sulfuric acid extraction and PA N-oxide reduction with zinc and purification.

CONCLUSIONS

In terms of sensitivity and discrimination, formic acid extraction in combination with LC-MS/MS detection is the method of choice for analysing PAs (both free and N-oxides forms) in plant material.

Interleukin-1 is essential for systemic inflammatory bone loss

OBJECTIVES

Chronic inflammation is a major risk factor for systemic bone loss leading to osteoporotic fracture and substantial morbidity and mortality. Inflammatory cytokines, particularly tumour necrosis factor (TNF) and interleukin-1 (IL1), are thought to play a key role in the pathogenesis of inflammation-induced bone loss, but their exact roles are yet to be determined.

METHODS

To determine whether TNF directly triggers bone loss or requires IL1, human TNFalpha mice (hTNFtg) were crossed with mice lacking IL1alpha and IL1beta (IL1(-/-)hTNFtg). Systemic bone architecture was evaluated using CT scanning, static and dynamic bone histomorphometry and serum markers of bone metabolism.

RESULTS

hTNFtg mice developed severe bone loss accompanied by a severe distortion of bone microarchitecture. Bone trabeculae were thinner and decreased in numbers, resulting in increased trabecular separation. Histomorphometric analyses revealed strongly increased bone resorption in hTNFtg mice compared with wild-type mice. In contrast, IL1(-/-)hTNFtg mice were fully protected from systemic bone loss despite still developing inflammation in their joints. Lack of IL1 completely reversed increased osteoclast formation and bone resorption in hTNFtg mice and the increased levels of RANKL in these mice. Structural parameters and osteoclast and osteoblast numbers were indistinguishable from wild-type mice.

CONCLUSIONS

These data indicate that IL1 is essential for TNF-mediated bone loss. Despite TNF-mediated inflammatory arthritis, systemic bone is fully protected by the absence of IL1, which suggests that IL1 is an essential mediator of inflammatory osteopenia.

[Dutch observation scales to assess cognitive abilities of the aged]

Assessment of complex geriatric health problems by nurses is important for diagnosis, especially assessment of cognitive functioning through daily observations. However, it is unclear which Dutch observation scales are available to assess cognitive abilities. In this study, we present an overview of these scales. A systematic review was performed. Beforehand we determined criteria for inclusion of scales and we searched through Dutch and English databases up till May 2005. Thirteen behavioural observation scales were found. The number of dimensions of cognitive functioning assessed in the scales varied greatly, from two to eight in number. Memory and psychomotor behaviour were always included; consciousness and thinking were frequently included, while alertness, perception, executive functions and language were least included. Extensive assessment of cognitive functioning is highly relevant for a geriatric hospital ward in which patients are admitted for diagnosis. Of all scales that we traced, the A-one is the most extensive: all eight dimensions are included. Little is known about the potential for using the A-one scale in nursing practice; further exploration is indicated. For now, nurses should become acquainted with the different dimensions of cognitive functioning and start to integrate observations in these dimensions in their reporting.

Transdifferentiation of polymorphonuclear neutrophils to dendritic-like cells at the site of inflammation in rheumatoid arthritis: evidence for activation by T cells

OBJECTIVES

To investigate infiltrated cells in the synovial fluid (SF) of inflamed joints of patients with rheumatoid arthritis (RA), with special reference to polymorphonuclear neutrophils (PMN) and their interaction with T cells.

METHODS

Expression on PMN of activation associated receptors CD14, CD64, CD83, and major histocompatibility complex (MHC) class II was examined in the SF of 15 patients with RA, as were the infiltrated T cells. SF cytokines were determined by enzyme linked immunosorbent assay (ELISA). To mimic the in vivo situation, co-culture experiments were carried out using PMN and T cells of healthy donors.

RESULTS

The SF contained activated T lymphocytes and abundant PMN. SF PMN expression of CD14 and CD64 was enhanced compared with peripheral blood. Of special interest was the observation that only the SF PMN expressed MHC class II antigens and CD83. Exposure to SF, which contained considerable amounts of cytokines (for example, interferon gamma (IFNgamma), tumour necrosis factor alpha, and interleukin 2), induced a similar receptor pattern on blood derived PMN of healthy donors. Furthermore, PMN acquired MHC class II and CD83 within 24 to 48 hours, when co-cultured with autologous T cells or T cell lines. This effect was also achieved by T cell supernatants, was dependent on protein synthesis, and could be inhibited by antibodies against IFNgamma.

CONCLUSIONS

SF PMN from patients with RA undergo major alterations, including transdifferentiation to cells with dendritic-like characteristics, probably induced by T cell derived cytokines. Because MHC class II positive PMN are known to activate T cells, the mutual activation of PMN and T cells might contribute to the perpetuation of the local inflammatory process, and eventually to the destructive process in RA.

Quantitation of the changes in vascularity during arthritis in the knee joint of a mouse with a digital image analysis system

Many joint and bone diseases are caused by, or associated with vascular changes. Particularly in rheumatoid arthritis, vascular sprouting of synovial vessels plays a major role in the generation of joint pathology. To assess the effects of pharmaceuticals that are designed to inhibit neovascularization, we developed a quantitative procedure to measure vascular changes in cross-sections of the mouse knee joint during arthritic inflammation. Arthritis was induced in the knee joint of C57Black6 mice by a single subpatellar injection of methylated BSA after previous immunization. Total vascularity was visualized with a specific monoclonal rat anti-mouse antibody (9F1). Functional vessels were detected with the fluorescent perfusion marker Hoechst 33342. The localization of Hoechst and the vascular marker 9F1 were analyzed in separate images with an automated digital image processing system. By combining the two images, total vascularity and the perfusion status of the vessels during arthritis could be established. The digital image system measures synovial area (SA), number of all blood vessels (NBV) and the number of perfused blood vessels (NpBV). From these parameters the percentage of perfused vessels (perfusion fraction; PF), the vessel density (VD = NBV/SA) and the density of perfused vessels (VDp = NpBV/SA) can be calculated. The measurements showed that the area of synovial tissue had increased during arthritis. Moreover, both the number of blood vessels (NBV) and the number of perfused vessels (NpBV) in the synovial area had increased significantly on Days 4 and 7 after arthritis induction. This procedure enabled quantitation of total vascularity and of functional blood vessels in cross-sections of synovial tissue. It is expected to be a powerful tool, not only to analyze the effects of anti-angiogenic therapies in animal models of arthritis, but could also be applicable to study vascular and perfusion changes in vascular related diseases of the skeleton.

Fluconazole and amphotericin B antifungal susceptibility testing by National Committee for Clinical Laboratory Standards broth macrodilution method compared with E-test and semiautomated broth microdilution test

A comparative study of fluconazole and amphotericin B susceptibility testing was performed with 68 clinical Candida species isolates and three test methods. The methods used were an agar diffusion method (E-test) and two broth dilution methods, the National Committee for Clinical Laboratory Standards (NCCLS) reference broth macrodilution method and an in-house-prepared semiautomated broth microdilution method based on the Bioscreen turbidometer. In the microdilution method, growth of the yeasts was measured continuously by the automatic turbidometer (Bioscreen), which permitted precise and objective determination of endpoints. MIC endpoints were read after 24 h for the microdilution method and the E-test. Amphotericin B susceptibility testing with the NCCLS method and the E-test yielded comparable results in 89% of the tests, meaning that the endpoints obtained were identical or differed by no more than 2 twofold dilutions. The NCCLS and broth microdilution tests scored 97% comparable results, and the E-test and the broth microdilution test yielded 90% comparable results. Fluconazole susceptibility testing produced 96% comparable results with the NCCLS test and the E-test, 100% comparable results with the NCCLS and the microdilution methods, and 98.5% comparable results with the microdilution method and the E-test. We conclude that the E-test and the Bioscreen microdilution method are valuable alternatives to the NCCLS reference method for routine susceptibility testing of Candida species with fluconazole and amphotericin B.