Genetic determinants of fungi-induced ROS production are associated with the risk of invasive pulmonary aspergillosis

Reactive oxygen species (ROS) are an essential component of the host defense against fungal infections. However, little is known about how common genetic variation affects ROS-mediated antifungal host defense. In the present study, we investigated the genetic factors that regulate ROS production capacity in response to the two human fungal pathogens: Candida albicans and Aspergillus fumigatus. We investigated fungal-stimulated ROS production by immune cells isolated from a population-based cohort of approximately 200 healthy individuals (200FG cohort), and mapped ROS-quantitative trait loci (QTLs). We identified several genetic loci that regulate ROS levels (P < 9.99 × 10-6), with some of these loci being pathogen-specific, and others shared between the two fungi. These ROS-QTLs were investigated for their influence on the risk of invasive pulmonary aspergillosis (IPA) in a disease relevant context. We stratified hematopoietic stem-cell transplant (HSCT) recipients based on the donor's SNP genotype and tested their impact on the risk of IPA. We identified rs4685368 as a ROS-QTL locus that was significantly associated with an increased risk of IPA after controlling for patient age and sex, hematological malignancy, type of transplantation, conditioning regimen, acute graft-versus-host-disease grades III-IV, and antifungal prophylaxis. Collectively, this data provides evidence that common genetic variation can influence ROS production capacity, and, importantly, the risk of developing IPA among HSCT recipients. This evidence warrants further research for patient stratification based on the genetic profiling that would allow the identifications of patients at high-risk for an invasive fungal infection, and who would benefit the most from a preventive strategy.

Kallikrein augments the anticoagulant function of the protein C system in thrombin generation

BACKGROUND

Genetics play a significant role in coagulation phenotype and venous thromboembolism risk. Resistance to the anticoagulant activated protein C (APC) is an established risk for thrombosis. Herein, we explored the genetic determinants of thrombin generation (TG) and thrombomodulin (TM)-modulated TG using plasma from the Human Functional Genomics Project.

METHODS

Calibrated TG was measured both in absence and presence of TM using tissue factor as trigger. Genetic determinants of TG parameters and protein C pathway function were assessed using genome-wide single-nucleotide polymorphism (SNP) genotyping. Plasma samples were supplemented with purified apolipoprotein A-IV, prekallikrein, or kallikrein to test their influence on the anticoagulant function of TM and APC in TG.

RESULTS

Thrombin generation data from 392 individuals were analyzed. Genotyping showed that the KLKB1 gene (top SNP: rs4241819) on chromosome 4 was associated with the normalized sensitivity ratio of endogenous thrombin potential to TM at genome-wide level (nETP-TMsr, P = 4.27 × 10-8 ). In vitro supplementation of kallikrein, but not prekallikrein or apolipoprotein A-IV, into plasma dose-dependently augmented the anticoagulant effect of TM and APC in TG. Variations of rs4241819 was not associated with the plasma concentration of prekallikrein. Association between rs4241819 and nETP-TMsr was absent when TG was measured in presence of a contact pathway inhibitor corn trypsin inhibitor.

CONCLUSIONS

Our results suggest that kallikrein plays a role in the regulation of the anticoagulant protein C pathway in TG, which may provide a novel mechanism for the previously observed association between the KLKB1 gene and venous thrombosis.

No Signs of Neuroinflammation in Women With Chronic Fatigue Syndrome or Q Fever Fatigue Syndrome Using the TSPO Ligand [11C]-PK11195

Background and Objectives

The pathophysiology of chronic fatigue syndrome (CFS) and Q fever fatigue syndrome (QFS) remains elusive. Recent data suggest a role for neuroinflammation as defined by increased expression of translocator protein (TSPO). In the present study, we investigated whether there are signs of neuroinflammation in female patients with CFS and QFS compared with healthy women, using PET with the TSPO ligand ¹¹C-(R)-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinoline-carbox-amide ([¹¹C]-PK11195).

Methods

The study population consisted of patients with CFS (n = 9), patients with QFS (n = 10), and healthy subjects (HSs) (n = 9). All subjects were women, matched for age (±5 years) and neighborhood, aged between 18 and 59 years, who did not use any medication other than paracetamol or oral contraceptives, and were not vaccinated in the last 6 months. None of the subjects reported substance abuse in the past 3 months or reported signs of underlying psychiatric disease on the Mini-International Neuropsychiatric Interview. All subjects underwent a [¹¹C]-PK11195 PET scan, and the [¹¹C]-PK11195 binding potential (BP_ND) was calculated.

Results

No statistically significant differences in BP_ND were found for patients with CFS or patients with QFS compared with HSs. BP_ND of [¹¹C]-PK11195 correlated with symptom severity scores in patients with QFS, but a negative correlation was found in patients with CFS.

Discussion

In contrast to what was previously reported for CFS, we found no significant difference in BP_ND of [¹¹C]-PK11195 when comparing patients with CFS or QFS with healthy neighborhood controls. In this small series, we were unable to find signs of neuroinflammation in patients with CFS and QFS.

Trial Registration Information

EudraCT number 2014-004448-37.

The Architecture of Circulating Immune Cells Is Dysregulated in People Living With HIV on Long Term Antiretroviral Treatment and Relates With Markers of the HIV-1 Reservoir, Cytomegalovirus, and Microbial Translocation

Long-term changes in the immune system of successfully treated people living with HIV (PLHIV) remain incompletely understood. In this study, we assessed 108 white blood cell (WBC) populations in a cohort of 211 PLHIV on stable antiretroviral therapy and in 56 HIV-uninfected controls using flow cytometry. We show that marked differences exist in T cell maturation and differentiation between PLHIV and HIV-uninfected controls: PLHIV had reduced percentages of CD4+ T cells and naïve T cells and increased percentages of CD8+ T cells, effector T cells, and T helper 17 (Th17) cells, together with increased Th17/regulatory T cell (Treg) ratios. PLHIV also exhibited altered B cell maturation with reduced percentages of memory B cells and increased numbers of plasmablasts. Determinants of the T and B cell composition in PLHIV included host factors (age, sex, and smoking), markers of the HIV reservoir, and CMV serostatus. Moreover, higher circulating Th17 percentages were associated with higher plasma concentrations of interleukin (IL) 6, soluble CD14, the gut homing chemokine CCL20, and intestinal fatty acid binding protein (IFABP). The changes in circulating lymphocytes translated into functional changes with reduced interferon (IFN)- γ responses of peripheral blood mononuclear cells to stimulation with Candida albicans and Mycobacterium tuberculosis. In conclusion, this comprehensive analysis confirms the importance of persistent abnormalities in the number and function of circulating immune cells in PLHIV on stable treatment.

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

Gout, Hyperuricaemia and Crystal-Associated Disease Network (G-CAN) consensus statement regarding labels and definitions of disease states of gout

OBJECTIVE

There is a lack of standardisation in the terminology used to describe gout. The aim of this project was to develop a consensus statement describing the recommended nomenclature for disease states of gout.

METHODS

A content analysis of gout-related articles from rheumatology and general internal medicine journals published over a 5-year period identified potential disease states and the labels commonly assigned to them. Based on these findings, experts in gout were invited to participate in a Delphi exercise and face-to-face consensus meeting to reach agreement on disease state labels and definitions.

RESULTS

The content analysis identified 13 unique disease states and a total of 63 unique labels. The Delphi exercise (n=76 respondents) and face-to-face meeting (n=35 attendees) established consensus agreement for eight disease state labels and definitions. The agreed labels were as follows: 'asymptomatic hyperuricaemia', 'asymptomatic monosodium urate crystal deposition', 'asymptomatic hyperuricaemia with monosodium urate crystal deposition', 'gout', 'tophaceous gout', 'erosive gout', 'first gout flare' and 'recurrent gout flares'. There was consensus agreement that the label 'gout' should be restricted to current or prior clinically evident disease caused by monosodium urate crystal deposition (gout flare, chronic gouty arthritis or subcutaneous tophus).

CONCLUSION

Consensus agreement has been established for the labels and definitions of eight gout disease states, including 'gout' itself. The Gout, Hyperuricaemia and Crystal-Associated Disease Network recommends the use of these labels when describing disease states of gout in research and clinical practice.

OR04-2 Aldosterone Induces Trained Immunity via Fatty Acid Synthesis

Hyperaldosteronism is associated with an increased cardiovascular risk in humans. Animal models show that aldosterone accelerates the development of atherosclerotic plaques, and suggest that this is, at least in part, mediated by activation of innate immune cells by aldosterone (1). Human data are scarce. We recently showed that monocytes can adopt a long-term pro-inflammatory phenotype after brief stimulation, which has been termed ‘trained immunity’ (2). Therefore, we tested the hypothesis that aldosterone induces ‘trained immunity’ by investigating the functional, immunometabolic and epigenetic effects of aldosterone on human monocytes in vitro. Human monocytes were exposed to vehicle, aldosterone (10nM) or serum obtained from patients with primary hyperaldosteronism (PA) with and without addition of a mineralocorticoid receptor (MR) antagonist for 24 hours, and differentiated to macrophages. We assessed the ability of these cells to produce ROS and cytokines upon re-stimulation. Changes in immunometabolism were assessed via extracellular flux measurements with Seahorse XF technology and further explored at the genome level with RNA microarray. Chromatin immunoprecipitation was performed to assess histone modifications in aldosterone-exposed cells. In vitro exposure of human monocytes with both aldosterone and PA serum induced a trained immunity phenotype characterized by augmented IL-6 and TNF-α responses, as well as ROS production to re-stimulation, an effect that was prevented by the MR antagonist spironolactone. Aldosterone-trained cells showed no differences in glycolysis or oxidative phosphorylation compared to vehicle treated cells. Instead, RNA microarray showed upregulation of the fatty acid synthesis (FAS) pathway, which we validated with qPCR. Pharmacological inhibition of FAS abolished the induction of training by aldosterone. Moreover, the aldosterone-trained phenotype was associated with enrichment of the transcriptionally-permissive histone mark H3K4me3, at the level of the promoters of central genes in the fatty acid synthesis pathway. In conclusion, aldosterone induces a form of trained immunity which is dependent on activation of the MR and induction of fatty acid synthesis. This novel pathway of immune activation uncovers potential pharmacological targets for patients with hyperaldosteronism. To translate these findings, we have recruited 15 patients with proven primary hyperaldosteronism and 15 matched patients with essential hypertension and comprehensively assessed systemic inflammation and monocyte phenotype as well as vascular wall inflammation with fluorodeoxyglucose-positron emission tomography. The results of these analyses will be available at the time of ENDO 2019. (1) van der Heijden et al. Cardiovasc Res. 2018 Jun 1;114(7):944-953. (2) Netea et al. Science. 2016 Apr 22;352(6284)

The effect of host genetics on the gut microbiome

The gut microbiome is affected by multiple factors, including genetics. In this study, we assessed the influence of host genetics on microbial species, pathways and gene ontology categories, on the basis of metagenomic sequencing in 1,514 subjects. In a genome-wide analysis, we identified associations of 9 loci with microbial taxonomies and 33 loci with microbial pathways and gene ontology terms at P < 5 × 10^-8. Additionally, in a targeted analysis of regions involved in complex diseases, innate and adaptive immunity, or food preferences, 32 loci were identified at the suggestive level of P < 5 × 10^-6. Most of our reported associations are new, including genome-wide significance for the C-type lectin molecules CLEC4F-CD207 at 2p13.3 and CLEC4A-FAM90A1 at 12p13. We also identified association of a functional LCT SNP with the Bifidobacterium genus (P = 3.45 × 10^-8) and provide evidence of a gene-diet interaction in the regulation of Bifidobacterium abundance. Our results demonstrate the importance of understanding host-microbe interactions to gain better insight into human health.

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.

High efficacy of Toll-like receptor 4 targeting in murine and humanized models of rheumatoid arthritis in comparison with IL-1 and TNF inhibitors (THER6P.860)

Enhanced expression of Toll-like Receptor (TLR) 4 and its endogenous agonists in rheumatoid joints suggests involvement in rheumatoid arthritis (RA). We assessed therapeutic efficacy and downstream effects of TLR4 blockade in murine and humanized models of RA compared with interleukin-1 (IL-1) and tumor necrosis factor (TNF) inhibitors. TLR4 blockade using purified B. quintana LPS suppressed established collagen-induced arthritis, and reduced serum IL-1β and IL-6 concentrations to the same extent as IL-1 and TNF inhibitors. TLR4 targeting exceeded beneficial effects of TNF blocker by reducing serum TNFα and IL-17 along with synovial expression of IL-23p19, IL-17 and the Th17-related transcription factor RORγt, while Th1 markers and type II collagen-directed T cell proliferation and antibody responses remained unaffected. To translate the findings into human disease, RA synovial biopsies were engrafted into SCID mice. TLR4 inhibition in this model resulted in reduction of spontaneous IL-6 and IL-8 release by RA synovium and reduced synovial inflammation, thereby equaling anti-TNF therapy. In ex vivo cultures of RA synovial explants, high-density protein microarray revealed suppressed activation of multiple key signaling molecules including NFκBp65 phospho-Ser536 (27%), TAK1 phospho-Thr187 and -Ser412 (26 and 23%, resp.), JAK1 phospho-Tyr1022 (22%), IRF3 (51%), Foxo3a (39%) and Btk (24%). The data collectively suggest TLR4 as a potential therapeutic target in RA.

High-density lipoprotein cholesterol subfractions HDL2 and HDL3 are reduced in women with rheumatoid arthritis and may augment the cardiovascular risk of women with RA: a cross-sectional study

INTRODUCTION

Higher levels of high density lipoprotein (HDL) subfractions HDL3-chol and particularly HDL2-chol protect against cardiovascular disease (CVD), but inflammation reduces the HDL level and may impair its anti-atherogenic effect. Changed HDL composition through the impact of inflammation on HDL subfractions may contribute to the excess risk of CVD in rheumatoid arthritis (RA). In this study, we investigated whether HDL2-chol and HDL3-chol concentrations differ between RA patients and healthy controls, and whether these levels are related to the level of RA disease activity.

METHODS

Non-fasting blood samples were collected from 45 RA patients and 45 healthy controls. None of the participants had a history of CVD, diabetes, or used lipid-lowering drugs. HDL2-chol and HDL3-chol concentrations were obtained by ultracentrifugation. Regression modeling was used to compare HDL subfraction levels between RA patients and healthy controls, and to analyze the effect of disease activity on HDL2-chol and HDL3-chol.

RESULTS

HDL2-chol and HDL3-chol were significantly lower in RA patients compared to healthy controls (P = 0.01, P = 0.005, respectively). The HDL2:HDL3 ratio was significantly lower in patients compared to controls (P = 0.04). Reduced HDL2-chol and HDL3-chol levels were primarily present in female RA patients and not in male RA patients. A modest effect of the disease activity score in 28 joins ( DAS28) on HDL2-chol concentrations was found, after correction for disease duration, glucocorticosteroid use and body mass index (BMI), with a 0.06 mmol/L decrease with every point increase in DAS28 (P = 0.05). DAS28 did not significantly affect HDL3-chol concentrations (P = 0.186).

CONCLUSIONS

Both HDL subfractions but particularly HDL2-chol concentrations were decreased in RA, primarily in women. This seems to be associated with disease activity and is of clinical relevance. The reduction of the HDL subfraction concentrations, particularly the supposedly beneficial HDL2-chol, may negatively impact the cardiovascular risk profile of women with RA.

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.

Anti IL-17A therapy inhibits bone loss in TNF-α-mediated murine arthritis by modulation of the T-cell balance

Tumour necrosis factor alpha (TNF-α) is a major inducer for inflammation and bone loss. Here, we investigated whether interleukin (IL)-17 plays a role in TNF-α-mediated inflammation and bone resorption. Human TNF-α transgenic (hTNFtg) mice were treated with a neutralizing anti-IL-17A antibody and assessed for inflammation, cartilage and bone damage. T-cell transcription factors and lymphokine patterns were measured in the LNs. IL-17A inhibition in the absence of IL-1 was also evaluated by treating hTNFtg/IL-1(-/-) mice with an IL-17A neutralizing antibody. IL-17A neutralization had only minor effects on TNF-α-induced inflammation but effectively reduced local and systemic bone loss by blocking osteoclast differentiation in vivo. Effects were based on a shift to bone-protective T-cell responses such as enhanced Th2 differentiation, IL-4 and IL-12 expression and Treg cell numbers. Whereas inflammation in hTNFtg/IL-1(-/-) mice was highly sensitive to IL-17A blockade, no shift in the T-cell lineages and no additional benefit on bone mass were observed in response to IL-17A neutralization. We thus conclude that IL-17A is a key mediator of TNF-α-induced bone loss by closely interacting with IL-1 in blocking bone protective T-cell responses.

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.

Neisseria meningitidis lipid A mutant LPSs function as LPS antagonists in humans by inhibiting TLR 4-dependent cytokine production

Lipopolysaccharide is a major constituent of the outer membrane of Gram-negative bacteria and important in the induction of pro-inflammatory responses. Recently, novel LPS species derived from Neisseria meningitidis H44/76 by insertional inactivation of the lpxL1 and lpxL2 genes have been created with a lipid A portion consisting of five (penta-acylated lpxL1) or four (tetra-acylated lpxL2) fatty acids connected to the glucosamine backbone instead of six fatty acids in the wild-type LPS. We show that these mutant LPS-types are poor inducers of cytokines (tumor-necrosis factor-α, IL-1β, IL-10, IL-RA) in human mononuclear cells. Both penta- and tetra-acylated meningococcal LPSs were able to inhibit cytokine production by wild-type Escherichia coli or meningococcal LPS. Binding of FITC-labelled E. coli LPS TLR4 transfected Chinese hamster ovary (CHO) cells was inhibited by both mutant LPS-types. Experiments with CHO fibroblasts transfected with human CD14 and TLR4 showed that the antagonizing effect was dependent on the expression of human TLR4. In contrast to the situation in humans, lpxL1 LPS has agonistic activity for cytokine production in peritoneal macrophages of DBA mice, and exacerbated arthritis in murine collagen induced arthritis model. N. meningitidis lipid A mutant LPSs lpxL1 and lpxL2 function as LPS antagonists in humans by inhibiting TLR4-dependent cytokine production but have agonistic activity in mice.

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.

TNF-induced structural joint damage is mediated by IL-1

Blocking TNF effectively inhibits inflammation and structural damage in human rheumatoid arthritis (RA). However, so far it is unclear whether the effect of TNF is a direct one or indirect on up-regulation of other mediators. IL-1 may be one of these candidates because it has a central role in animal models of arthritis, and inhibition of IL-1 is used as a therapy of human RA. We removed the effects of IL-1 from a TNF-mediated inflammatory joint disease by crossing IL-1alpha and beta-deficient mice (IL-1-/-) with arthritic human TNF-transgenic (hTNFtg) mice. Development of synovial inflammation was almost unaffected on IL-1 deficiency, but bone erosion and osteoclast formation were significantly reduced in IL-1-/-hTNFtg mice, compared with hTNFtg mice based on an intrinsic differentiation defect of IL-1-deficient monocytes. Most dramatically, however, cartilage damage was absent in IL-1-/-hTNFtg mice. Chimera studies revealed that protection of cartilage is based on the loss of IL-1 on hematopoietic, but not mesenchymal, cells, leading to decreased expression of ADAMTS-5 and MMP-3. These data show that TNF-mediated cartilage damage is completely and TNF-mediated bone damage is partially dependent on IL-1, suggesting that IL-1 is a crucial mediator for inflammatory cartilage and bone degradation.

[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.

Functional consequences of the Asp299Gly Toll-like receptor-4 polymorphism

Toll-like receptor-4 (TLR4) is a pattern-recognition receptor not only for exogenous ligands such as lipopolysaccharide (LPS) of Gram-negative bacteria, but also for endogenous ligands such as fibronectin, heat shock proteins and hyaluronan oligosaccharides. The Asp299Gly allele of the TLR4 gene has been associated with increased risk for severe infections, but reduced progression of atherosclerosis. We have investigated the consequences of the presence of Asp299Gly polymorphism after stimulation of mononuclear cells with lipopolysaccharide (LPS), the non-LPS TLR4 microbial stimuli Aspergillus fumigatus and Cryptococcus neoformans, and the endogenous TLR4 ligand heat shock protein 60. No differences in either production of the proinflammatory cytokine TNF or the antiinflammatory cytokine interleukin-10 were observed between volunteers with the wild-type allele, volunteers heterozygous for the Asp299Gly allele and one volunteer homozygous for the TLR4 variant. In conclusion, the presence of the Asp299Gly TLR4 polymorphism does not result in defective pro and antiinflammatory cytokine production after stimulation with either exogenous (LPS and non-LPS) or endogenous TLR4 ligands, and alternative explanations are likely to be responsible for the epidemiological data showing associations with inflammatory conditions. In addition, this is the first study to demonstrate that even homozygosity for the Asp299Gly mutation does not confer hyporesponsiveness to stimulation with TLR4 stimuli.

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.

IL-17 derived from juxta-articular bone and synovium contributes to joint degradation in rheumatoid arthritis

The origin and role of IL-17, a T-cell derived cytokine, in cartilage and bone destruction during rheumatoid arthritis (RA) remain to be clarified. In human ex vivo models, addition of IL-17 enhanced IL-6 production and collagen destruction, and inhibited collagen synthesis by RA synovium explants. On mouse cartilage, IL-17 enhanced cartilage proteoglycan loss and inhibited its synthesis. On human RA bone explants, IL-17 also increased bone resorption and decreased formation. Addition of IL-1 in these conditions increased the effect of IL-17. Blocking of bone-derived endogenous IL-17 with specific inhibitors resulted in a protective inhibition of bone destruction. Conversely, intra-articular administration of IL-17 into a normal mouse joint induced cartilage degradation. In conclusion, the contribution of IL-17 derived from synovium and bone marrow T cells to joint destruction suggests the control of IL-17 for the treatment of RA.

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.