Anti-IgLON5 Disease: A New Bulbar-Onset Motor Neuron Mimic Syndrome

Objective

To expand the spectrum of anti-IgLON5 disease by adding 5 novel anti-IgLON5–seropositive cases with bulbar motor neuron disease-like phenotype.

Methods

We characterized the clinical course, brain MRI and laboratory findings, and therapy response in these 5 patients.

Results

Patients were severely affected by bulbar impairment and its respiratory consequences. Sleep-related breathing disorders and parasomnias were common. All patients showed clinical or electrophysiologic signs of motor neuron disease without fulfilling the diagnostic criteria for amyotrophic lateral sclerosis. One patient regained autonomy in swallowing and eating, possibly related to immunotherapy.

Conclusion

IgLON5 disease is an important differential diagnosis to evaluate in patients with bulbar motor neuron disease-like phenotype and sleep disorders. There is need for a deeper understanding of the underlying pathobiology to determine whether IgLON5 disease is an immunotherapy-responsive condition.

Systemic and mucosal antibody responses specific to SARS-CoV-2 during mild versus severe COVID-19

BACKGROUND

Whereas severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific antibody tests are increasingly being used to estimate the prevalence of SARS-CoV-2 infection, the determinants of these antibody responses remain unclear.

OBJECTIVES

Our aim was to evaluate systemic and mucosal antibody responses toward SARS-CoV-2 in mild versus severe coronavirus disease 2019 (COVID-19) cases.

METHODS

Using immunoassays specific for SARS-CoV-2 spike proteins, we determined SARS-CoV-2-specific IgA and IgG in sera and mucosal fluids of 2 cohorts, including SARS-CoV-2 PCR-positive patients (n = 64) and PCR-positive and PCR-negtive health care workers (n = 109).

RESULTS

SARS-CoV-2-specific serum IgA titers in patients with mild COVID-19 were often transiently positive, whereas serum IgG titers remained negative or became positive 12 to 14 days after symptom onset. Conversely, patients with severe COVID-19 showed a highly significant increase of SARS-CoV-2-specific serum IgA and IgG titers after symptom onset. Very high titers of SARS-CoV-2-specific serum IgA were correlated with severe acute respiratory distress syndrome. Interestingly, some health care workers with negative SARS-CoV-2-specific serum antibody titers showed SARS-CoV-2-specific IgA in mucosal fluids with virus-neutralizing capacity in some cases. SARS-CoV-2-specific IgA titers in nasal fluids were inversely correlated with age.

CONCLUSIONS

Systemic antibody production against SARS-CoV-2 develops mainly in patients with severe COVID-19, with very high IgA titers seen in patients with severe acute respiratory distress syndrome, whereas mild disease may be associated with transient production of SARS-CoV-2-specific antibodies but may stimulate mucosal SARS-CoV-2-specific IgA secretion.

Systemic and mucosal antibody responses specific to SARS-CoV-2 during mild versus severe COVID-19

BACKGROUND

Whereas severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific antibody tests are increasingly being used to estimate the prevalence of SARS-CoV-2 infection, the determinants of these antibody responses remain unclear.

OBJECTIVES

Our aim was to evaluate systemic and mucosal antibody responses toward SARS-CoV-2 in mild versus severe coronavirus disease 2019 (COVID-19) cases.

METHODS

Using immunoassays specific for SARS-CoV-2 spike proteins, we determined SARS-CoV-2-specific IgA and IgG in sera and mucosal fluids of 2 cohorts, including SARS-CoV-2 PCR-positive patients (n = 64) and PCR-positive and PCR-negtive health care workers (n = 109).

RESULTS

SARS-CoV-2-specific serum IgA titers in patients with mild COVID-19 were often transiently positive, whereas serum IgG titers remained negative or became positive 12 to 14 days after symptom onset. Conversely, patients with severe COVID-19 showed a highly significant increase of SARS-CoV-2-specific serum IgA and IgG titers after symptom onset. Very high titers of SARS-CoV-2-specific serum IgA were correlated with severe acute respiratory distress syndrome. Interestingly, some health care workers with negative SARS-CoV-2-specific serum antibody titers showed SARS-CoV-2-specific IgA in mucosal fluids with virus-neutralizing capacity in some cases. SARS-CoV-2-specific IgA titers in nasal fluids were inversely correlated with age.

CONCLUSIONS

Systemic antibody production against SARS-CoV-2 develops mainly in patients with severe COVID-19, with very high IgA titers seen in patients with severe acute respiratory distress syndrome, whereas mild disease may be associated with transient production of SARS-CoV-2-specific antibodies but may stimulate mucosal SARS-CoV-2-specific IgA secretion.

Recurrent Herpes Zoster Ophthalmicus in a Patient With a Novel Toll-Like Receptor 3 Variant Linked to Compromised Activation Capacity in Fibroblasts

BACKGROUND

Herpes zoster ophthalmicus occurs primarily in elderly or immunocompromised individuals after reactivation of varicella zoster virus (VZV). Recurrences of zoster ophthalmicus are uncommon because the reactivation efficiently boosts anti-VZV immunity. A 28-year-old female presented to our clinic with a history of multiple recurrences of zoster ophthalmicus.

METHODS

Whole-exome sequencing (WES), analyses of VZV T-cell immunity, and pathogen recognition receptor function in primary antigen-presenting cells (APCs) and fibroblasts were performed.

RESULTS

Normal VZV-specific T-cell immunity and antibody response were detected. Whole-exome sequencing identified a heterozygous nonsynonymous variant (c.2324C > T) in the Toll-like receptor 3 (TLR3) gene resulting in formation of a premature stop-codon. This alteration could potentially undermine TLR3 signaling in a dominant-negative fashion. Therefore, we investigated TLR3 signaling responses in APCs and fibroblasts from the patient. The APCs responded efficiently to stimulation with TLR3 ligands, whereas the responses from the fibroblasts were compromised.

CONCLUSIONS

We report a novel TLR3 variant associated with recurrent zoster ophthalmicus. Toll-like receptor 3 responses that were unaffected in APCs but diminished in fibroblasts are in line with previous reports linking TLR3 deficiency with herpes simplex virus encephalitis. Mechanisms involving compromised viral sensing in infected cells may thus be central to the described immunodeficiency.

A distinct innate immune signature marks progression from mild to severe COVID-19

Coronavirus disease 2019 (COVID-19) manifests with a range of severities, but immune signatures of mild and severe disease are still not fully understood. Here, we use mass cytometry and targeted proteomics to profile the innate immune response of patients with mild or severe COVID-19 and of healthy individuals. Sampling at different stages allows us to reconstruct a pseudo-temporal trajectory of the innate response. A surge of CD169+ monocytes associated with an IFN-γ+MCP-2+ signature rapidly follows symptom onset. At later stages, we observe a persistent inflammatory phenotype in patients with severe disease, dominated by high CCL3 and CCL4 abundance correlating with the re-appearance of CD16+ monocytes, whereas the response of mild COVID-19 patients normalizes. Our data provide insights into the dynamic nature of inflammatory responses in COVID-19 patients and identify sustained innate immune responses as a likely mechanism in severe patients, thus supporting the investigation of targeted interventions in severe COVID-19.

SAC during early cell divisions: Sacrificing fidelity over timely division, regulated differently across organisms: Chromosome alignment and segregation are left unsupervised from the onset of development until checkpoint activity is acquired, varying from species to species

Early embryogenesis is marked by a frail Spindle Assembly Checkpoint (SAC). The time of SAC acquisition varies depending on the species, cell size or a yet to be uncovered developmental timer. This means that for a specific number of divisions, biorientation of sister chromatids occurs unsupervised. When error-prone segregation is an issue, an aneuploidy-selective apoptosis system can come into play to eliminate chromosomally unbalanced cells resulting in healthy newborns. However, aneuploidy content can be too great to overcome, endangering viability. SAC generates a diffusible signal to lengthen time spent in mitosis if needed, ensuring correct chromosome segregation, a fundamental factor in the generation of euploid cells. Thus, it remains puzzling what benefit could come from delaying SAC acquisition till later in the development. In this review, we describe what is known on SAC acquisition in distinct species and highlight pending research as well as potential applications for such knowledge.

CD40 levels in plasma are associated with cardiovascular disease and in carotid plaques with a vulnerable plaque phenotype and remodelling

Background and purpose

CD40 and CD40 ligand (CD40L) are costimulatory molecules and members of the TNF receptor superfamily well known for their involvement in inflammatory and autoimmune diseases. This study uses two large human cohorts – the SUrrogate markers for Micro- and Macro-vascular hard endpoints for Innovative diabetes Tools (SUMMIT) and the Carotid Plaque Imaging Project (CPIP) – to explore the potential of plasma or intra-plaque expression of CD40 and CD40L as biomarkers and to locally affect plaque stability.

Methods

Proximity Extension Assay (PEA) technique was used to measure soluble CD40 and CD40L (sCD40 and sCD40L) in plasma from 1437 subjects from the SUMMIT cohort, the majority of which (80%) with pre-existing cardiovascular disease, and in atherosclerotic plaque homogenates from 199 subjects of the CPIP cohort undergoing carotid endarterectomy. The Mann-Whitney U test was used to compare groups and Spearman's rank correlation/the Chi-square test was used to assess correlations. Multiple comparisons were corrected for using the Holm-Šídák test. A logistic regression model was used to test for associations with future cardiovascular events and mortality.

Results

In the SUMMIT cohort both plasma CD40 and CD40L levels were elevated in individuals with a history of stroke (p=0.000030 and p=0.020, respectively), while sCD40 levels also were higher in individuals with a prior acute myocardial infarction (p=0.016). Plasma levels of sCD40 correlated with carotid plaque burden (as measured by ultrasound imaging, r=0.355, p<1x10–16) and were associated with future cardiovascular events over a three year-follow up period (p=0.02, hazard ratio 1.3, 95% C.I: 1.042–1.625).

sCD40 and sCD40L were associated with a plaque phenotype characterized by the strong presence of features both of vulnerability such as high content oxidized low-density lipoprotein (LDL; r=0.236, p=0.004 and r=0.259, p=0.0037, respectively) and pro-inflammatory cytokines (e.g. tumour necrosis factor-α: p=3.1x10–7 and p=0.0006, respectively) and low calcium content (r=−0.208, p=0.012 and r=0.268, p=0.00034, respectively).

Conclusion

High plasma CD40 and CD40L levels are associated with symptomatic cardiovascular disease. Plasma CD40 levels correlate with the severity of carotid atherosclerosis and are associated with an increased risk for future cardiovascular events. Additionally, intra-plaque levels are associated with a vulnerable plaque phenotype. Our findings thus support the value of sCD40 and sCD40L both as biomarkers and therapeutic targets for cardiovascular disease.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): The Swedish Heart and Lung Foundation (1) and the Swedish Research Council (2)

Collagen remodeling markers show differentiated expression in patients with ST- and non-ST elevation myocardial infarction

Background

Following acute myocardial infarction (MI), the left ventricle undergoes molecular and extracellular matrix (ECM) changes. The ECM is a dynamic structure with a potential role in cardiac remodeling post-MI. Collagens are the major components of both cardiac and arterial ECM.

Purpose

We evaluated circulating levels of type I, IV and VI collagen fragments in two cohorts of patients with acute MI to investigate collagen turnover post-MI. The cohorts were Malmö AMI in elderly (MAMI-Y) and Assessing Platelet Activity in Coronary Heart Disease (APACHE).

Methods

Serum was collected from 190 patients from the discovery cohort (MAMI-Y: mean age 74, SD 10.8) at four timepoints: admission when MI, after 3–6 days, 6 weeks, 12 months; citrate plasma was collected from 142 patients from the validation cohort (APACHE: mean age 65, SD 11.6) at four timepoints: hospitalization, 3 days, 7–9 days, 6 months. The biomarkers of matrix metalloproteinase (MMP)-mediated degradation of type I collagen (C1M), MMP-mediated degradation of type IV collagen (C4M) and formation of type VI collagen (PRO-C6) were measured at all timepoints (immunosorbent assays). Differences in the markers at the different timepoints were calculated using repeated measures ANOVA.

Results

Circulating levels of the formation biomarker PRO-C6 significantly increased from baseline and remained high at all three following timepoints in both MAMI-Y and APACHE studies (all p<0.001). In contrast, the degradation biomarkers C1M and C4M showed a similar pattern of an initial increase 3 days post-MI followed by a decrease over time, with C1M in MAMI-Y and both C1M and C4M in APACHE having returned to baseline level by the final timepoint. Circulating baseline levels of PRO-C6 correlated with age (r=0.397, p<0.0001 in MAMI-Y, r=0.427, p<0.0001 in APACHE). Categorizing the subjects into ST elevation MI (STEMI; MAMI-Y: N=67, APACHE: N=71) or non-ST elevation MI (NSTEMI; MAMI-Y: N=130, APACHE: N=52) revealed that a correlation with age remained in both subgroups (r=0.443, p<0.0001 and r=0.325, p<0.0001, respectively, in MAMI-Y, and r=0.516, p<0.0001 and r=0.316, p=0.023, respectively, in APACHE). Moreover, PRO-C6 was elevated in STEMI patients that had previously experienced an MI in both cohorts (MAMI-Y: p=0.017, APACHE: p=0.016). C1M and C4M levels were not different in patients with prior MI in any of the cohorts. No association was found between any biomarker and gender or diabetes. Echocardiography showed a correlation between baseline levels of C1M and ejection fraction (r=0.228, p=0.023) in the whole MAMI-Y cohort and among NSTEMI, but not among STEMI, subjects (r=0.337, p=0.004).

Conclusions

We observed changes in circulating fragments reflecting collagen turnover in the acute phase post-MI, more pronounced in STEMI patients. This may indicate that STEMI patients have more active collagen remodeling than NSTEMI patients and may have more altered left ventricle function and remodeling.

Funding Acknowledgement

Type of funding source: Other. Main funding source(s): This work was supported by the Danish Research Foundation “den danske forskningsfond”, the Innovation foundation (Innovationsfonden), Swedish Research Council, Swedish Heart and Lung Foundation, Swedish Society for Medical Research, Swedish Society of Medicine, the Crafoord Foundation, the Åke Wiberg foundation and the Stroke foundation.

The Gly82Ser polymorphism in the receptor for advanced glycation end products is associated with increased risk for coronary events in the general population

Background/Introduction

Activation of the receptor for advanced glycation end products (RAGE) by AGEs and various immune mediators has pro-inflammatory and pro-atherogenic effects. RAGE also exists in a soluble form, sRAGE, that acts as a decoy receptor for RAGE ligands. Low plasma sRAGE has previously been found to be associated with a higher risk for major adverse coronary events (MACE) in the population.

Purpose

The purpose of our study was to examine the causality of the association, by exploring whether genetic variants that influence sRAGE are associated with atherosclerosis progression and incident MACE and mortality in the population.

Methods

We performed a genome-wide association study (GWAS) in 4192 individuals from a randomly selected subgroup of a population-based cohort. Subsequently, we explored the associations between the identified single nucleotide polymorphims (SNPs) associated with plasma sRAGE levels, baseline intima media thickness (IMT) and IMT progression in the common carotid artery during a median follow-up of 16.5 years. Further, we analyzed the prospective relationships between the sRAGE-associated SNPs, incident MACE and mortality in the entire population-based cohort of 29245 individuals. The median follow-up time from baseline was 21.2 years for MACE and 21.6 years for total mortality (time to event or end of follow-up).

Results

We found the minor alleles of two single nucleotide polymorphisms (SNPs), rs2070600 and rs204993, to be independently associated with lower plasma sRAGE. While rs204993 is a silent intronic mutation, rs2070600 is known to cause a Gly82Ser polymorphism in the ligand binding domain, enhancing RAGE propensity for activation. In Cox regression analyses, we found an association between the minor T (vs. C) allele of rs2070600 and increased risk for first-time MACE [HR 1.12 (1.02–1.23); P=0.023]. The association was independent of traditional cardiovascular risk factors, blood pressure-lowering medication and lipid-lowering medication at baseline. rs204993 was not associated with MACE. Neither SNP was associated with carotid IMT at baseline or with IMT progression. We did not identify any relationships with total mortality.

Conclusions

We demonstrate for the first time an independent link between a genetic RAGE determinant and the risk for MACE in the population. Despite both identified SNPs being associated with lower sRAGE levels, only the functional rs2070600 mutation was associated with MACE, suggesting that the link is probably due to the enhancement of RAGE function rather than to the sRAGE lowering effect.

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): This study was supported by grants from the Swedish Research Council and the Swedish Heart and Lung foundation.

Quantitative kinase and phosphatase profiling reveal that CDK1 phosphorylates PP2Ac to promote mitotic entry

The reciprocal regulation of phosphoprotein phosphatases (PPPs) by protein kinases is essential to cell cycle progression and control, particularly during mitosis for which the role of kinases has been extensively studied. PPPs perform much of the serine/threonine dephosphorylation in eukaryotic cells and achieve substrate selectivity and specificity through the interaction of distinct regulatory subunits with conserved catalytic subunits in holoenzyme complexes. Using a mass spectrometry-based chemical proteomics approach to enrich, identify, and quantify endogenous PPP holoenzyme complexes combined with kinase profiling, we investigated the phosphorylation-dependent regulation of PPP holoenzymes in mitotic cells. We found that cyclin-dependent kinase 1 (CDK1) phosphorylated a threonine residue on the catalytic subunit of the phosphatase PP2A, which disrupted its holoenzyme formation with the regulatory subunit B55. The consequent decrease in the dephosphorylation of PP2A-B55 substrates promoted mitotic entry. This direct phosphorylation by CDK1 was in addition to a previously reported indirect mechanism, thus adding a layer to the interaction between CDK1 and PP2A in regulating mitotic entry.

Benralizumab in eosinophilic granulomatosis with polyangiitis complicated by Staphylococcus aureus sepsis

Eosinophilic Granulomatosis with Polyangiitis (EGPA) is an ANCA-associated small-vessels vasculitis characterized by hypereosinophilia and eosinophilic asthma. EGPA with life-threatening organ involvement, particularly cardiac and central nervous system (CNS), is a medical emergency requiring immediate immunosuppression. We describe a 58-year-old patient with a history of chronic rhinosinusitis and eosinophilic asthma, who presented with fever, hypereosinophilia and systemic inflammation. Diagnostic workup identified a cardiac mass, CNS vasculitis, CNS embolization and Staphylococcus aureus in blood cultures. Due to rapid normalization of blood cultures, the intracardiac mass was not considered as primarily infective. Active EGPA with cardiac and CNS involvement complicated by a secondary S. aureus sepsis was diagnosed. In order to not negatively impact antibacterial immunity in active EGPA, antibiotic therapy was combined with Benralizumab, which was well tolerated and EGPA resolved rapidly. Benralizumab could serve as a therapeutic option for eosinophil-mediated pathologies in severely ill patients where immunosuppressives are initially contraindicated.

Stereoretentive Nucleophilic Substitution at the Tetrasubstituted Carbon of Galiellalactone

The fungal metabolite galiellalactone (1) was, as its acetate 4, discovered to undergo a substitution reaction with cysteine derivatives. By studying the reaction mechanism and the intermediates formed, and in an effort to expand the chemical diversity of the galiellalactonoids, a mild and general method of preparing ether, thioether, and amine analogues of galiellalactone was developed. The reaction is a formal stereoretentive nucleophilic substitution at an oxygenated tertiary carbon. NMR analysis of the progressing reaction shows that it involves an initial allylic substitution to form a new Michael acceptor, followed by the addition of a second equivalent of the nucleophile to this and, finally, a retro Michael reaction. This restores the original galiellalactone system with a double bond between C-2a and C-3, but with a new substituent at C-7b. As galiellalactone is a promising STAT3 inhibitor, this novel transformation facilitates the semisynthesis of a wide variety of new analogues for structure-activity relationship studies.

AB1199 COST-EFFECTIVENESS OF EARLY INITIATION OF ABATACEPT ON JAPANESE RHEUMATOID ARTHRITIS PATIENTS BASED ON THE AMPLE STUDY, USING IORRA REAL WORLD DATA

Background:

Rheumatoid arthritis (RA) is a chronic inflammatory disorder leading to disability and reduced quality of life. Effective treatment with biologic disease-modifying antirheumatic drugs (bDMARD) poses a significant economic burden. The abatacept (ABT) versus adalimumab comparison in biologic-naive RA subjects with background methotrexate (AMPLE) trial1was a head-to-head randomized study.

Objectives:

To assess the cost-effectiveness (CE) of early initiation of ABT on Japanese RA patients with data from the IORRA database (ID).2

Methods:

A model based on the AMPLE study was used to estimate the CE of ABT 1stversus ABT 2ndlines in a cohort of 1000 patients based on responses on ACR20/50/70, HAQ-DI, CDAI and SDAI estimated from the real-clinical data of the ID. Unit costs for direct medical costs of adverse events (AEs), proportions of patients with concomitant medications or outpatient/inpatient visits; doses and duration of concomitant medications were taken from the JMDC claims database.3Uncertainty was assessed in sensitivity analyses (SA) where cost parameters were tested on their ±30% levels. Results were compared between subgroups using cut-offs of 65-years of age and 1.5 of HAQ, or 5-years of treatment duration. The study used a Japanese healthcare payers’ perspective over a 2-year time horizon.

Results:

Incremental costs were all in favor of ABT 2ndline with 137 MJPY (1.1 M€, 120 JPY=1 €), 6 MJPY (0.05 M€), 41 MJPY (0.3 M€), 8 MJPY (0.07 M€) and 2.2 MJPY (0.02 M€) for bDMARDs, concomitant medication, AEs, serious AE, and hospitalizations due to infections, respectively. In total, the incremental costs were expected to be 195 MJPY (1.6 M€) higher for ABT as 1stline treatment, but the cost per responding patient and per patient in remission favored ABT 1stline across most response outcomes (Table 1).

Table 1.

Total costs per responder and patient in remission per 2-year

Difference in cost per health gain(ABT first line - ABT second line)Cost per responding patient (kJPY)ACR20-2,927 (-24 k€)ACR50-6,406 (-53 k€)ACR70-10,822 (-90 k€)HAQ-DI-5,120 (-43 k€)Cost per patient in remission (kJPY)DAS28828 (7 k€)CDAI-7,019 (-58 k€)SDAI-5,584 (-47 k€)

ABT=abatacept; ACR20/50/70= 20/50/70% improvement of the American college of rheumatology criteria; HAQ-DI=health assessment questionnaire disability index; DAS28=disease activity score; CDAI=clinical disease activity index; SDAI=simplified disease activity index

SA showed that the cost for bDMARDs drives the difference in healthcare costs between the cohorts (-685 MJPY to 1,074 MJPY). For sub-groups of patients ≥65 years, <65 years, HAQ≥1.5, HAQ <1.5, treatment duration ≥5 years, <5 years the total 2-yearly costs per responder (SDAI remission) were 106 kJPY (0.9 k€), 321 kJPY (2.7 k€), 1,353 kJPY (11.3 k€), 106 kJPY (0.9 k€), 231 kJPY (1.9 k€) and 178 kJPY (1.5 k€) lower for ABT 1stline, respectively.

Conclusion:

Savings per responding patient are expected if ABT are prescribed as 1stline versus 2ndor 3rdline treatment, irrespective of age, disease duration and functional impairment level.

References:

[1]Sokolove J MS et al.,Anna rheum dis.2015;74(Suppl 2)

[2]IORRA cohort database, Tokyo Women’s Medical University, Tokyo, Japan

[3]JMDC claims database, Tokyo, Japan

Disclosure of Interests:

Eiichi Tanaka Consultant of: ET has received lecture fees or consulting fees from Abbvie, Asahi Kasei pharma co., Bristol Myers Squibb, Chugai Pharmaceutical, Daiichi Sankyo Co., Eisai Pharmaceutical, Janssen Pharmaceutical K.K., Nippon Kayaku, Pfizer, Takeda Pharmaceutical, Taisho Toyama Pharmaceutical Co., and UCB Pharma., Speakers bureau: ET has received lecture fees or consulting fees from Abbvie, Asahi Kasei pharma co., Bristol Myers Squibb, Chugai Pharmaceutical, Daiichi Sankyo Co., Eisai Pharmaceutical, Janssen Pharmaceutical K.K., Nippon Kayaku, Pfizer, Takeda Pharmaceutical, Taisho Toyama Pharmaceutical Co., and UCB Pharma., Eisuke Inoue Speakers bureau: EI has received speaker fee from Bristol-Meyers, Pfizer, Merck serono., Ayako Shoji Consultant of: To conduct this work, Jonas Nilsson Consultant of: To conduct this study, Christos Papagiannopoulos Consultant of: To conduct this study, Dhanda Devender Shareholder of: BMS, Employee of: BMS, Yoshio Anazawa Shareholder of: BMS, Employee of: BMS, Yuri Yoshizawa Shareholder of: BMS, Employee of: BMS, masayoshi harigai Grant/research support from: AbbVie Japan GK, Ayumi Pharmaceutical Co., Bristol Myers Squibb Co., Ltd., Eisai Co., Ltd., Mitsubishi Tanabe Pharma Co., Nippon Kayaku Co., Ltd., and Teijin Pharma Ltd. MH has received speaker’s fee from AbbVie Japan GK, Ayumi Pharmaceutical Co., Boehringer Ingelheim Japan, Inc., Bristol Myers Squibb Co., Ltd., Chugai Pharmaceutical Co., Ltd., Eisai Co., Ltd., Eli Lilly Japan K.K., GlaxoSmithKline K.K., Kissei Pharmaceutical Co., Ltd., Oxford Immuotec, Pfizer Japan Inc., and Teijin Pharma Ltd. MH is a consultant for AbbVie, Boehringer-ingelheim, Kissei Pharmaceutical Co., Ltd. and Teijin Pharma.

Escape from the checkpoint: Nek2A binds a unique conformation of the APC/C-MCC complex

Cell division depends on the timely degradation of numerous proteins by the anaphase-promoting complex/cyclosome (APC/C). The APC/C is a large E3 ubiquitin ligase that in complex with Cdc20 recognises degrons in its substrates. The ability of APC/C-Cdc20 to bind degrons is prevented by the binding of the mitotic checkpoint complex (MCC) which constitutes the "wait anaphase" signal. Curiously, the mitotic kinase Nek2A is insensitive to the presence of the MCC. How Nek2A avoids MCC inhibition has been unclear but now work from Alfieri and colleagues published in this issue of EMBO reports provides an explanation [1]. It shows that Nek2A is able to bind a specific open conformation of the APC/C-MCC complex that allows Nek2A ubiquitination. A dimer of Nek2A binds two distinct binding pockets on the APC/C through C-terminal MR motifs and thus independently of degrons. One of the MR binding pockets is only available for interaction in the open form of APC/C-MCC explaining Nek2A selectivity for this conformation. Whether other substrates bind the APC/C directly without using canonical degrons will be important to determine.

Mechanisms of site-specific dephosphorylation and kinase opposition imposed by PP2A regulatory subunits

PP2A is an essential protein phosphatase that regulates most cellular processes through the formation of holoenzymes containing distinct regulatory B‐subunits. Only a limited number of PP2A‐regulated phosphorylation sites are known. This hampers our understanding of the mechanisms of site‐specific dephosphorylation and of its tumor suppressor functions. Here, we develop phosphoproteomic strategies for global substrate identification of PP2A‐B56 and PP2A‐B55 holoenzymes. Strikingly, we find that B‐subunits directly affect the dephosphorylation site preference of the PP2A catalytic subunit, resulting in unique patterns of kinase opposition. For PP2A‐B56, these patterns are further modulated by affinity and position of B56 binding motifs. Our screens identify phosphorylation sites in the cancer target ADAM17 that are regulated through a conserved B56 binding site. Binding of PP2A‐B56 to ADAM17 protease decreases growth factor signaling and tumor development in mice. This work provides a roadmap for the identification of phosphatase substrates and reveals unexpected mechanisms governing PP2A dephosphorylation site specificity and tumor suppressor function.

Exploring the role of extracellular matrix proteins to develop biomarkers of plaque vulnerability and outcome

Cardiovascular disease (CVD) is the most common cause of death in industrialized countries. One underlying cause is atherosclerosis, which is a systemic disease characterized by plaques of retained lipids, inflammatory cells, apoptotic cells, calcium and extracellular matrix (ECM) proteins in the arterial wall. The biologic composition of an atherosclerotic plaque determines whether the plaque is more or less vulnerable, that is prone to rupture or erosion. Here, the ECM and tissue repair play an important role in plaque stability, vulnerability and progression. This review will focus on ECM remodelling in atherosclerotic plaques, with focus on how ECM biomarkers might predict plaque vulnerability and outcome.

A dynamic charge-charge interaction modulates PP2A:B56 substrate recruitment

The recruitment of substrates by the ser/thr protein phosphatase 2A (PP2A) is poorly understood, limiting our understanding of PP2A-regulated signaling. Recently, the first PP2A:B56 consensus binding motif, LxxIxE, was identified. However, most validated LxxIxE motifs bind PP2A:B56 with micromolar affinities, suggesting that additional motifs exist to enhance PP2A:B56 binding. Here, we report the requirement of a positively charged motif in a subset of PP2A:B56 interactors, including KIF4A, to facilitate B56 binding via dynamic, electrostatic interactions. Using molecular and cellular experiments, we show that a conserved, negatively charged groove on B56 mediates dynamic binding. We also discovered that this positively charged motif, in addition to facilitating KIF4A dephosphorylation, is essential for condensin I binding, a function distinct and exclusive from PP2A-B56 binding. Together, these results reveal how dynamic, charge-charge interactions fine-tune the interactions mediated by specific motifs, providing a new framework for understanding how PP2A regulation drives cellular signaling.

Pretransplant Kinetics of Anti-HLA Antibodies in Patients on the Waiting List for Kidney Transplantation

BACKGROUND

Patients on organ transplant waiting lists are evaluated for preexisting alloimmunity to minimize episodes of acute and chronic rejection by regularly monitoring for changes in alloimmune status. There are few studies on how alloimmunity changes over time in patients on kidney allograft waiting lists, and an apparent lack of research-based evidence supporting currently used monitoring intervals.

METHODS

To investigate the dynamics of alloimmune responses directed at HLA antigens, we retrospectively evaluated data on anti-HLA antibodies measured by the single-antigen bead assay from 627 waitlisted patients who subsequently received a kidney transplant at University Hospital Zurich, Switzerland, between 2008 and 2017. Our analysis focused on a filtered dataset comprising 467 patients who had at least two assay measurements.

RESULTS

Within the filtered dataset, we analyzed potential changes in mean fluorescence intensity values (reflecting bound anti-HLA antibodies) between consecutive measurements for individual patients in relation to the time interval between measurements. Using multiple approaches, we found no correlation between these two factors. However, when we stratified the dataset on the basis of documented previous immunizing events (transplant, pregnancy, or transfusion), we found significant differences in the magnitude of change in alloimmune status, especially among patients with a previous transplant versus patients without such a history. Further efforts to cluster patients according to statistical properties related to alloimmune status kinetics were unsuccessful, indicating considerable complexity in individual variability.

CONCLUSIONS

Alloimmune kinetics in patients on a kidney transplant waiting list do not appear to be related to the interval between measurements, but are instead associated with alloimmunization history. This suggests that an individualized strategy for alloimmune status monitoring may be preferable to currently used intervals.

P5510High plasma sRAGE is associated with slower carotid intima media thickness progression and lower risk for first-time coronary events and mortality

Background/Introduction

The receptor for advanced glycation end products (RAGE) and the extracellular matrix metalloproteinase inducer (EMMPRIN) are immune receptors for pro-inflammatory mediators. These receptors can also be found in a soluble form in the circulation. Soluble RAGE (sRAGE) has shown atheroprotective properties in animal studies, by acting as a decoy receptor for its ligands. Whether sEMMPRIN has similar roles is unknown.

Purpose

The purpose of our study was to investigate the associations between sRAGE and sEMMPRIN in plasma and the progression of vascular disease, incident coronary events and mortality in the general population.

Methods

We measured baseline sRAGE and sEMMPRIN in 4612 cardiovascular disease-free middle aged individuals from a population-based cohort. Measurements of intima media thickness (IMT) in the common carotid artery were performed at inclusion and after a median of 16.5 years. Incident major adverse coronary events (MACE) and mortality were recorded during a follow-up period of 21 years.

Results

sRAGE was negatively correlated with the progression of carotid IMT, independently of traditional cardiovascular risk factors, kidney function and hsCRP. Additionally, sRAGE was associated with decreased risk for MACE [HR=0.91 (0.83–0.99); p=0.031] and total mortality [HR=0.92 (0.87–0.99); p=0.017] in multivariate Cox regression analyses. We found no correlations between EMMPRIN, IMT progression or prognosis.

Conclusion

We show that individuals with high levels of circulating sRAGE have a slower rate of carotid artery disease progression, and a lower risk for coronary events and mortality. These findings support further research into the potential atheroprotective properties of sRAGE.

Acknowledgement/Funding

This study was supported by grants from the Swedish Research Council, Marianne and Marcus Wallenberg Foundation, Swedish Heart and Lung Foundation

5949Interleukin-6 and growth differentiation factor-15 in hypertensive heart failure

Background

Hypertension is the leading cause for the development of heart failure (HF). Increased hemodynamic load, including mechanical stretch and neurohumoral factors, is able to trigger hypertrophic growth of cardiac myocytes. Although hypertensive HF is prevalent, there is no useful biomarker to identify HF due to chronic hypertension.

Aims

To identify plasma markers associated with incidence of hypertensive HF.

Methods

Circulating levels of 149 proteins were measured by proximity extension assay at baseline examination in 4469 individuals from the Malmö Diet and Cancer study. Protein levels were compared to stretch-activated gene expression changes in cultured neonatal rat ventricular myocytes (NRVM) in response to 1, 4, 12, 24 or 48 hours of cyclic mechanical stretch. Association between plasma proteins level and HF incidence and hypertension was studied using respectively Cox proportional hazards model and binary logistic regressions.

Results

After Bonferroni correction, 44 circulating proteins were significantly differentially expressed in individuals who developed HF during follow-up versus controls (P<3.4E-4). Out of these, 5 proteins (Interleukin-6 (IL-6), Growth Differentiation Factor-15 (GDF15), Interleukin-1 Receptor-Like-1 (ST2), Plasminogen Activator Urokinase Receptor (U-PAR), Transforming Growth Factor-α (TGF-α)), corresponding mRNA levels were upregulated by mechanical stretch in NRVM at all time points (P<0.05). Similar upregulation for the 5 proteins was shown in hypertensive versus normotensive individuals (P≤8.05E-4). In a model with all 5 proteins entered simultaneously, GDF15 and IL-6 were predictive of incident HF after adjustment for age, sex and NT-BNP levels (205 events; hazard ratio [HR] per SD increment of protein: HR=1.29, CI=1.05–1.58, P=0.013 and HR=1.16, CI=1.02–1.33, P=0.028). Using the same model, IL-6 but not GDF15 associated with hypertension (Odds ratio [OR] per SD increment of IL-6: OR=1.18, CI=1.09–1.27, P=3.3E-5). In hypertensive individuals GDF15 and IL-6 were individually predictive of future HF after adjustment for age, sex, NT-BNP levels, smoking, BMI and diabetes (183 events; HR=1.36, CI=1.16–1.60, P=1.64E-4 and HR=1.21, CI=1.05–1.40, P=0.008). Furthermore, in these hypertensive individuals, GDF15 and IL-6 were predictive of HF in a model with IL-6, GDF15, ST2 and TGF-α entered simultaneously after adjustment for age, sex and NT-BNP levels (176 events; HR=1.36, CI=1.13–1.64, P=0.001 and HR=1.16, CI=1.01–1.34, P=0.041).

Conclusions

Circulating levels of IL-6 and GDF15 might be used as NT-BNP independent biomarkers for HF development in hypertensive patients.

Acknowledgement/Funding

Påhlsson, Crafoord, Lundström, Åke Wiberg, Royal Physiographic Society and the Swedish Foundation for Strategic Research for IRC15-0067

3046High levels of MMP-cleaved mimecan is associated to carotid plaque stability and less future cardiovascular events

Introduction

The clinical consequences of atherosclerosis, myocardial infarction and stroke are the most common causes of death globally. Mimecan, a small leucine rich-repeat proteoglycan (SLRP), is cleaved by matrix metalloproteinases (MMPs) and known to be involved in collagen fibrillogenesis and angiogenesis. Circulating levels of MMP-cleaved mimecan (cMIM) has previously been identified as a marker of extracellular matrix remodelling in ApoE−/− knockout mice. The role of mimecan and its degradation in human atherosclerotic plaques has not been explored.

Purpose

We explored whether full-length mimecan and cleaved mimecan (cMIM) are associated to plaque composition and evaluated if they can predict future cardiovascular events.

Methods

Two hundred and eighteen human atherosclerotic plaques were stained for mimecan using immunohistochemistry. cMIM was measured in 202 plaque tissue homogenates using a competitive ELISA assay. Histological components (α-actin, CD68 and glycophorin A) were assessed using immunohistochemistry, neutral lipids were measured using Oil Red O and visible areas of calcium deposits were quantified. Matrix metalloproteinases (MMP-1, -2, -3, -9, -10 and -12), tissue inhibitors of matrix metalloproteinases (TIMP-1 and -2) were analysed in plaque tissue homogenates using ELISA assays and a proximity extension assay. ECM components (glycosaminoglycans, collagen and elastin) were detected with colorimetric assays and the TGF-β1, β2 and β3 were measured by a multiplex assay. Cardiovascular events were registered using national registers, patient records and telephone calls during a follow-up period of 59 months IQR (34–73).

Results

Mimecan was expressed in human atherosclerotic plaques. The expression correlated positively with neutral lipids and intraplaque hemorrhage and inversely with α-actin. In contrast cMIM correlated with α-actin and inversely with neutral lipids. cMIM correlated also with stabilizing extracellular matrix proteins elastin, collagen as well as TGF-β1, β2 and β3. Mimecan correlated to MMP-9 and cMIM correlated to MMP-2 and TIMP-2. Patient with high levels of cMIM had a lower risk of future cardiovascular events which remained significant after adjusting for risk factors (age, gender, diabetes and symptoms) in a multivariate Cox regression

Conclusion(s)

Mimecan was associated with vulnerable plaque features, whereas cMIM was related to stable plaque features. Low levels of cMIM predicted future cardiovascular events, independently of known risk factors. Taken together this suggests a possible role for mimecan and its cleavage in atherosclerosis that needs to be further explored.

Acknowledgement/Funding

Danish Research Foundation, Swedish Research Council, Swedish Heart and Lung Foundation, Skåne University Hospital and more.

3043Endotrophin, a fragment of collagen type VI, is correlated to IMT and associated with cardiovascular events in patients with atherosclerosis and diabetes: the IMI-SUMMIT cohort

Background/Introduction

Patients with micro- and macrovascular diseases, including atherosclerosis, have increased risk of cardiovascular events and early mortality. The atherosclerotic disease is characterised by accumulation of lipids, cells and proteins in the arterial wall, which includes remodelling of the extracellular matrix (ECM). Collagen type VI (COL6) is known to be over-expressed in patients with atherosclerosis. The biomarker PRO-C6, known as endotrophin, is a COL6 fragment that reflects formation of collagen type VI, and possess pro-inflammatory and pro-fibrotic activities.

Purpose

We explored whether increased endotrophin levels, measured by PRO-C6, were associated with intima-media thickness (IMT) and mortality in the IMI-SUMMIT cohort.

Methods

Circulating protein levels of PRO-C6 were measured in EDTA plasma from 1500 patients enrolled at four European University Hospitals, using an enzyme-linked immunosorbent assay. Follow-up data were available up to three years after sample collection. Associations between PRO-C6 and incidence of cardiovascular (CV) events and all-cause mortality were assessed by Kaplan-Meier curves and Cox proportional hazard regression analyses. Pearson correlation was performed to explore the association of PRO-C6, IMT and clinical variables. Known confounders defined by the Framingham Heart study (age, gender and diabetes) were included in the Cox proportional hazard regression analysis.

Results

Plasma PRO-C6 was significantly correlated with IMT in both the common carotid artery and the carotid bulb (r=0.09, p=0.002 and r=0.11, p=0.0003, respectively), HbA1c (r=0.11, p<0.0001) and C-reactive protein (r=0.14, p<0.0001). A total of 145 patients suffered from fatal or non-fatal cardiovascular events during the three-year follow-up period. Patients in the highest PRO-C6 tertile had a two-fold increased risk of experiencing a CV event during follow-up (p=0.002), independently of age, presence of CVD at baseline, type 2 diabetes, smoking and statin treatment in a regression model.

Conclusion

The present findings demonstrate that circulating levels of PRO-C6 are associated with atherosclerosis severity and increased incidence of cardiovascular events. Since PRO-C6 detects the signaling molecule endotrophin, the results may indicate that endotrophin is not only a biomarker of atherosclerotic disease, but may have a role in promoting disease progression.

Acknowledgement/Funding

This work was supported by the Danish Research Foundation, The Danish innovation foundation and the IMI-SUMMIT participants

Multi-level Proteomics Identifies CT45 as a Chemosensitivity Mediator and Immunotherapy Target in Ovarian Cancer

Most high-grade serous ovarian cancer (HGSOC) patients develop resistance to platinum-based chemotherapy and recur, but 15% remain disease free over a decade. To discover drivers of long-term survival, we quantitatively analyzed the proteomes of platinum-resistant and -sensitive HGSOC patients from minute amounts of formalin-fixed, paraffin-embedded tumors. This revealed cancer/testis antigen 45 (CT45) as an independent prognostic factor associated with a doubling of disease-free survival in advanced-stage HGSOC. Phospho- and interaction proteomics tied CT45 to DNA damage pathways through direct interaction with the PP4 phosphatase complex. In vitro, CT45 regulated PP4 activity, and its high expression led to increased DNA damage and platinum sensitivity. CT45-derived HLA class I peptides, identified by immunopeptidomics, activate patient-derived cytotoxic T cells and promote tumor cell killing. This study highlights the power of clinical cancer proteomics to identify targets for chemo- and immunotherapy and illuminate their biological roles.

Drivers of changing urban flood risk: A framework for action

This study focuses on drivers for changing urban flood risk. We suggest a framework for guiding climate change adaptation action concerning flood risk and manageability in cities. The identified key drivers of changing flood hazard and vulnerability are used to provide an overview of each driver's impact on flood risk and manageability at the city level. We find that identified drivers for urban flood risk can be grouped in three different priority areas with different time horizon. The first group has high impact but is manageable at city level. Typical drivers in this group are related to the physical environment such as decreasing permeability and unresponsive engineering. The second group of drivers is represented by public awareness and individual willingness to participate and urbanization and urban sprawl. These drivers may be important and are manageable for the cities and they involve both short-term and long-term measures. The third group of drivers is related to policy and long-term changes. This group is represented by economic growth and increasing values at risk, climate change, and increasing complexity of society. They have all high impact but low manageability. Managing these drivers needs to be done in a longer time perspective, e.g., by developing long-term policies and exchange of ideas.

Efficient mitotic checkpoint signaling depends on integrated activities of Bub1 and the RZZ complex

Kinetochore localized Mad1 is essential for generating a "wait anaphase" signal during mitosis, hereby ensuring accurate chromosome segregation. Inconsistent models for the function and quantitative contribution of the two mammalian Mad1 kinetochore receptors: Bub1 and the Rod-Zw10-Zwilch (RZZ) complex exist. By combining genome editing and RNAi, we achieve penetrant removal of Bub1 and Rod in human cells, which reveals that efficient checkpoint signaling depends on the integrated activities of these proteins. Rod removal reduces the proximity of Bub1 and Mad1, and we can bypass the requirement for Rod by tethering Mad1 to kinetochores or increasing the strength of the Bub1-Mad1 interaction. We find that Bub1 has checkpoint functions independent of Mad1 localization that are supported by low levels of Bub1 suggesting a catalytic function. In conclusion, our results support an integrated model for the Mad1 receptors in which the primary role of RZZ is to localize Mad1 at kinetochores to generate the Mad1-Bub1 complex.

Severe combined immunodeficiency (SCID) presenting in childhood, with agammaglobulinemia, associated with novel compound heterozygous mutations in DCLRE1C

Severe combined immunodeficiency (SCID) can be caused by deleterious mutations in DCLRE1C, leading to deficient non-homologous end joining by compromising the function of the Artemis protein. This impairs the process of V(D)J recombination of the T- and B-cell receptors and typically results in radiosensitive T^-, B^-, NK⁺ SCID presenting during the first months of life. We present a case of a 3-year-old girl with two novel compound heterozygous variants in DCLRE1C (c.58G>C and c.374A>C) that were associated with marked reduced numbers of peripheral T- and B-cells and undetectable total serum IgG. Despite the severe laboratory phenotype, the patient had a normal development, albeit failure to thrive (-2.5 to -3 SD), during her first years of life including day-care attendance at preschool for 1.5 years. After being diagnosed with pneumonia the clinical picture of SCID was recognized and the girl successfully underwent hematopoietic stem-cell transplantation.

A biomarker of collagen type I degradation is associated with cardiovascular events and mortality in patients with atherosclerosis

OBJECTIVE

Atherosclerosis is characterized by accumulation of lipids, cells and extracellular matrix (ECM) proteins in the arterial wall. Collagen type I (COL1), a component of the arterial ECM, is cleaved by matrix metalloproteinases (MMPs) and known to be remodelled in atherosclerosis. We explored whether the MMP-mediated COL1 biomarker, C1M, was associated with cardiovascular events, cardiovascular mortality and all-cause mortality in a large prospective cohort of patients with known atherosclerosis.

METHODS

Serum from 787 patients who underwent a carotid endarterectomy was included. Circulating levels of C1M were measured in serum. A total of 473 patients were followed for 6 years after surgery. Associations between C1M and incidence of cardiovascular events, cardiovascular mortality and all-cause mortality were assessed by Kaplan-Meier curves and Cox regression analysis.

RESULTS

A total of 101 (21.4%) patients suffered from nonfatal cardiovascular events during the follow-up period, and 64 (13.5%) patients died. Of these, 39 (60.9%) died from cardiovascular diseases. Patients with C1M levels above the median were significantly associated with cardiovascular events, cardiovascular mortality and all-cause mortality (P < 0.001, P = 0.004 and P < 0.001, respectively). C1M was included in the final model for prediction of cardiovascular events (HR 2.15, 95% CI 1.40-3.32, P = 0.001), cardiovascular mortality (HR 2.20, 95% CI 1.07-4.51, P = 0.031) and all-cause mortality (HR 2.98 95% CI 1.67-5.33, P = < 0.001).

CONCLUSIONS

In patients with atherosclerotic carotid lesions, high levels of C1M predicted cardiovascular events, cardiovascular mortality and all-cause mortality. These findings emphasize the importance of remodelling mechanisms in atherosclerosis that are now becoming more and more explored.

Anti-ApoA-I IgG antibodies are not associated with carotid artery disease progression and first-time cardiovascular events in middle-aged individuals

OBJECTIVE

IgG antibodies against apolipoprotein A-I (ApoA-I) have been found to be elevated in subjects from the general population with clinically manifest cardiovascular disease and in myocardial infarction patients with an adverse prognosis. Here, we investigated whether these antibodies are prospectively associated with carotid artery disease progression and with the risk for first-time cardiovascular events in individuals with no previous history of cardiovascular disease.

APPROACH AND RESULTS

We selected 383 subjects from the cardiovascular cohort of Malmö Diet and Cancer study who suffered a coronary event during a median follow-up period of 15.4 (10.3-16.4) years and 395 age- and sex-matched controls. None of the study participants had a previous history of coronary artery disease or stroke. Anti-ApoA-I IgG were measured by ELISA in serum samples collected at baseline. Intima-media thickness (IMT) was measured in the common carotid artery and in the carotid bifurcation at baseline and after 15.9 (±1.5) years. We found no associations between anti-ApoA-I IgG and carotid artery IMT at baseline or with IMT progression during follow-up. In Cox proportional hazards analyses adjusted for traditional cardiovascular risk factors, the hazard ratio (HR 95%CI) for the primary outcome, incident coronary events, was 0.97 (0.75-1.25), P = 0.782, in subjects with anti-ApoA-I IgG within the highest tertile compared with the lowest tertile. Similarly, we did not find any associations with the secondary outcome, incident first-time stroke.

CONCLUSIONS

Serum autoantibodies against ApoA-I do not correlate with disease progression and adverse events in cardiovascular disease-free individuals from the general population.

Protein phosphatases in the regulation of mitosis

The accurate segregation of genetic material to daughter cells during mitosis depends on the precise coordination and regulation of hundreds of proteins by dynamic phosphorylation. Mitotic kinases are major regulators of protein function, but equally important are protein phosphatases that balance their actions, their coordinated activity being essential for accurate chromosome segregation. Phosphoprotein phosphatases (PPPs) that dephosphorylate phosphoserine and phosphothreonine residues are increasingly understood as essential regulators of mitosis. In contrast to kinases, the lack of a pronounced peptide-binding cleft on the catalytic subunit of PPPs suggests that these enzymes are unlikely to be specific. However, recent exciting insights into how mitotic PPPs recognize specific substrates have revealed that they are as specific as kinases. Furthermore, the activities of PPPs are tightly controlled at many levels to ensure that they are active only at the proper time and place. Here, I will discuss substrate selection and regulation of mitotic PPPs focusing mainly on animal cells and explore how these actions control mitosis, as well as important unanswered questions.

Plasma levels of the proprotein convertase furin and incidence of diabetes and mortality

BACKGROUND

Diabetes mellitus is linked to premature mortality of virtually all causes. Furin is a proprotein convertase broadly involved in the maintenance of cellular homeostasis; however, little is known about its role in the development of diabetes mellitus and risk of premature mortality.

OBJECTIVES

To test if fasting plasma concentration of furin is associated with the development of diabetes mellitus and mortality.

METHODS

Overnight fasted plasma furin levels were measured at baseline examination in 4678 individuals from the population-based prospective Malmö Diet and Cancer Study. We studied the relation of plasma furin levels with metabolic and hemodynamic traits. We used multivariable Cox proportional hazards models to investigate the association between baseline plasma furin levels and incidence of diabetes mellitus and mortality during 21.3-21.7 years follow-up.

RESULTS

An association was observed between quartiles of furin concentration at baseline and body mass index, blood pressure and plasma concentration of glucose, insulin, LDL and HDL cholesterol (|0.11| ≤ β ≤ |0.31|, P < 0.001). Plasma furin (hazard ratio [HR] per one standard deviation increment of furin) was predictive of future diabetes mellitus (727 events; HR = 1.24, CI = 1.14-1.36, P < 0.001) after adjustment for age, sex, body mass index, systolic and diastolic blood pressure, use of antihypertensive treatment, alcohol intake and fasting plasma level of glucose, insulin and lipoproteins cholesterol. Furin was also independently related to the risk of all-cause mortality (1229 events; HR = 1.12, CI = 1.05-1.19, P = 0.001) after full multivariable adjustment.

CONCLUSION

Individuals with high plasma furin concentration have a pronounced dysmetabolic phenotype and elevated risk of diabetes mellitus and premature mortality.

Tests of size and growth effects on Arctic charr (Salvelinus alpinus) otolith δ18 O and δ13 C values

RATIONALE

Otolith δ¹⁸ O and δ¹³ C values have been used extensively to reconstruct thermal and diet histories. Researchers have suggested that individual growth rate and size may have an effect on otolith isotope ratios and subsequently confound otolith-based thermal and diet reconstructions. As few explicit tests of the effect on fish in freshwater environments exist, here we determine experimentally the potential for related growth rate and size effects on otolith δ¹⁸ O and δ¹³ C values.

METHODS

Fifty Arctic charr were raised in identical conditions for two years after which their otoliths were removed and analyzed for their δ¹⁸ O and δ¹³ C values. The potential effects of final length and the Thermal Growth Coefficient (TGC) on otolith isotope ratios were tested using correlation and regression analysis to determine if significant effects were present and to quantify effects when present.

RESULTS

The analyses indicated that TGC and size had significant and similar positive non-linear relationships with δ¹³ C values and explained 35% and 42% of the variability, respectively. Conversely, both TGC and size were found to have no significant correlation with otolith δ¹⁸ O values. There was no significant correlation between δ¹⁸ O and δ¹³ C values.

CONCLUSIONS

The investigation indicated the presence of linked growth rate and size effects on otolith δ¹³ C values, the nature of which requires further study. Otolith δ¹⁸ O values were unaffected by individual growth rate and size, confirming the applicability of these values to thermal reconstructions of fish habitat.

The closed form of Mad2 is bound to Mad1 and Cdc20 at unattached kinetochores

The spindle assembly checkpoint (SAC) ensures accurate chromosome segregation by delaying anaphase onset in response to unattached kinetochores. Anaphase is delayed by the generation of the mitotic checkpoint complex (MCC) composed of the checkpoint proteins Mad2 and BubR1/Bub3 bound to the protein Cdc20. Current models assume that MCC production is catalyzed at unattached kinetochores and that the Mad1/Mad2 complex is instrumental in the conversion of Mad2 from an open form (O-Mad2) to a closed form (C-Mad2) that can bind to Cdc20. Importantly the levels of Mad2 at kinetochores correlate with SAC activity but whether C-Mad2 at kinetochores exclusively represents its complex with Mad1 is not fully established. Here we use a recently established C-Mad2 specific monoclonal antibody to show that Cdc20 and C-Mad2 levels correlate at kinetochores and that depletion of Cdc20 reduces Mad2 but not Mad1 kinetochore levels. Importantly reintroducing wild type Cdc20 but not Cdc20 R132A, a mutant form that cannot bind Mad2, restores Mad2 levels. In agreement with this live cell imaging of fluorescent tagged Mad2 reveals that Cdc20 depletion strongly reduces Mad2 localization to kinetochores. These results support the presence of Mad2-Cdc20 complexes at kinetochores in agreement with current models of the SAC but also argue that Mad2 levels at kinetochores cannot be used as a direct readout of Mad1 levels.