Proteomic Characterization of Atherosclerotic Lesions In Situ Using Percutaneous Coronary Intervention Angioplasty Balloons-Brief Report

BACKGROUND

Materials extracted from atherosclerotic arteries can disclose data about the molecular pathology of cardiovascular disease, but obtaining such samples is complex and requires invasive surgery. To overcome this barrier, this study investigated whether angioplasty balloons inflated during standard percutaneous coronary interventions retain proteins from treated (dilated) atherosclerotic lesions and whether proteomic analysis of this material could provide data on lesion protein profiles and distinguish between patients with stable and unstable coronary artery disease.

METHODS

Patients with ST-segment-elevation myocardial infarction and stable angina pectoris were subjected to routine percutaneous coronary interventions. All angioplasty balloons inflated in a coronary artery were collected. Proteins retained on the balloons were extracted and analyzed using shotgun proteomic analysis.

RESULTS

Proteomics identified and quantified 1365 unique proteins captured on percutaneous coronary intervention balloons. Control balloons inflated in the ascending aorta showed minimal nonspecific protein binding, indicating specificity to the luminal region of atherosclerotic lesions of the diseased artery wall. Clustering and principal component analyses showed that ST-segment-elevation myocardial infarction and stable angina pectoris subjects could be separated by variations in protein content and abundance. We identified 206 proteins as differentially abundant between ST-segment-elevation myocardial infarction and stable angina pectoris subjects. Pathway analysis indicated several enriched processes in the ST-segment-elevation myocardial infarction group involved in neutrophil-mediated immunity and platelet activation.

CONCLUSIONS

Disease-related proteins from coronary artery lesions adhere to angioplasty balloons and constitute a source of material for proteomic analysis. This approach can identify proteins and processes occurring in unstable coronary atherosclerotic lesions and suggest novel therapeutic approaches.

Structural Basis for Dityrosine-Mediated Inhibition of α-Synuclein Fibrillization

α-Synuclein (α-Syn) is an intrinsically disordered protein which self-assembles into highly organized β-sheet structures that accumulate in plaques in brains of Parkinson’s disease patients. Oxidative stress influences α-Syn structure and self-assembly; however, the basis for this remains unclear. Here we characterize the chemical and physical effects of mild oxidation on monomeric α-Syn and its aggregation. Using a combination of biophysical methods, small-angle X-ray scattering, and native ion mobility mass spectrometry, we find that oxidation leads to formation of intramolecular dityrosine cross-linkages and a compaction of the α-Syn monomer by a factor of √2. Oxidation-induced compaction is shown to inhibit ordered self-assembly and amyloid formation by steric hindrance, suggesting an important role of mild oxidation in preventing amyloid formation.

Peroxynitrous acid-modified extracellular matrix alters gene and protein expression in human coronary artery smooth muscle cells and induces a pro-inflammatory phenotype

Leukocytes produce oxidants at inflammatory sites, including within the artery wall during the development of atherosclerosis. Developing lesions contain high numbers of activated leukocytes that generate reactive nitrogen species, including peroxynitrite/peroxynitrous acid (ONOO^-/ONOOH), as evidenced by the presence of oxidized/nitrated molecules including extracellular matrix (ECM) proteins. ECM materials are critical for arterial wall integrity, function, and determine cell phenotype, with smooth muscle cells undergoing a phenotypic switch from quiescent/contractile to proliferative/synthetic during disease development. We hypothesized that ECM modification by ONOO^-/ONOOH might drive this switch, and thereby potentially contribute to atherogenesis. ECM generated by primary human coronary artery smooth muscle cells (HCASMCs) was treated with increasing ONOO^-/ONOOH concentrations (1-1000 μM). This generated significant damage on laminin, fibronectin and versican, and lower levels on collagens and glycosaminoglycans, together with the increasing concentrations of the damage biomarker 3-nitrotyrosine. Adhesion of naïve HCASMC to ECM modified by 1 μM ONOO^-/ONOOH was enhanced, but significantly diminished by higher ONOO^-/ONOOH treatment. Cell proliferation and metabolic activity were significantly enhanced by 100 μM ONOO^-/ONOOH pre-treatment. These changes were accompanied by increased expression of genes involved in mitosis (PCNA, CCNA1, CCNB1), ECM (LAMA4, LAMB1, VCAN, FN1) and inflammation (IL-1B, IL-6, VCAM-1), and corresponding protein secretion (except VCAM-1) into the medium. These changes induced by modified ECM are consistent with HCASMC switching to a synthetic/proliferative/pro-inflammatory phenotype, together with ECM remodelling. These changes model those in atherosclerosis, suggesting a link between oxidant-modified ECM and disease progression, and highlight the potential of targeting oxidant generation as a therapeutic strategy.

Guidelines for measuring reactive oxygen species and oxidative damage in cells and in vivo

Multiple roles of reactive oxygen species (ROS) and their consequences for health and disease are emerging throughout biological sciences. This development has led researchers unfamiliar with the complexities of ROS and their reactions to employ commercial kits and probes to measure ROS and oxidative damage inappropriately, treating ROS (a generic abbreviation) as if it were a discrete molecular entity. Unfortunately, the application and interpretation of these measurements are fraught with challenges and limitations. This can lead to misleading claims entering the literature and impeding progress, despite a well-established body of knowledge on how best to assess individual ROS, their reactions, role as signalling molecules and the oxidative damage that they can cause. In this consensus statement we illuminate problems that can arise with many commonly used approaches for measurement of ROS and oxidative damage, and propose guidelines for best practice. We hope that these strategies will be useful to those who find their research requiring assessment of ROS, oxidative damage and redox signalling in cells and in vivo.

Synthesis and cellular evaluation of click-chemistry probes to study the biological effects of alpha, beta-unsaturated carbonyls

Humans are commonly exposed to α,β-unsaturated carbonyls as both environmental toxins (e.g. acrolein) and therapeutic drugs (e.g. dimethylfumarate, DMFU, a front-line drug for the treatment of multiple sclerosis and psoriasis). These compounds undergo rapid Michael addition reactions with amine, imidazole and thiol groups on biological targets, with reaction at protein Cys residues being a major reaction pathway. However, the cellular targets of these species (the ‘adductome’) are poorly understood due to the absence of readily identifiable tags or reporter groups (chromophores/fluorophores or antigens) on many α,β-unsaturated carbonyls. Here we report a ‘proof of concept’ study in which we synthesize novel α,β-unsaturated carbonyls containing an alkyne function introduced at remote sites on the α,β-unsaturated carbonyl compounds (e.g. one of the methyl groups of dimethylfumarate). The presence of this tag allows ‘click-chemistry’ to be used to visualize, isolate, enrich and characterize the cellular targets of such compounds. The probes show similar selectivity and reactivity to the parent compounds, and compete for cellular targets, yielding long-lived (stable) adducts that can be visualized in intact cells (such as primary human coronary artery smooth muscle cells), and extracted and enriched for subsequent target analysis. It is shown using this approach that dimethylfumarate forms adducts with multiple intracellular targets including cytoskeletal, organelle and nuclear species, with these including the rate-limiting glycolytic enzyme, glyceraldehyde-3-phosphate dehydrogenase (GAPDH). This approach should be amenable to use with multiple α,β-unsaturated carbonyls and a wide variety of targets containing nucleophilic sites.

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Humans are widely exposed to α,β-unsaturated carbonyls via drugs and environmental toxins.

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These compounds react with cellular targets, and particularly Cys residues, via Michael addition.

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Alkyne tagged derivatives have been synthesized to allow click chemistry detection.

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These tags allow visualization, extraction, enrichment and identification of adducted proteins.

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GAPDH reacts with dimethylfumarate, with adducts detected in both the cytosol and nucleus.

Associations between environmental exposures in the Middle East Area of Operations and pregnancy outcomes in Australian Defence Force veterans

Military personnel deployed on operations may encounter a variety of hazards with the capacity to adversely affect reproductive health. This paper investigates the association between self-reported exposure to reproductive toxicants and adverse pregnancy outcomes in Australian Defence Force veterans who deployed to Iraq and Afghanistan during the period 2001-2009. Utilising the Middle East Area of Operations (MEAO) Census Study data set, descriptive analyses of participants' self-reported exposure were compared with the occupational environmental monitoring data taken at their reported deployment location. Univariate analyses assessed the significance of unadjusted associations between self-reported exposures and reproductive outcomes. There is no systematic or consistent relationship between deployment to the MEAO and adverse pregnancy outcomes. Overall, self-reported adverse reproductive outcomes were significantly increased in veterans who deployed to both Afghanistan and Iraq (p = 0.04) compared to those who only deployed to only one of those locations; particularly in women (p = 0.009). Miscarriage was the most likely of these (p = 0.008). These figures would benefit from being confirmed against medical records but are worthy of further study. In this historical cohort study, causal inference cannot be made due to absence of control groups to exclude sources of potential bias. Imprecision in the assessment of environmental hazards in the MEAO and other methodological constraints make it impossible to calculate precise estimates of risk. The results warrant continued investigation, especially when combined with previous findings related to pregnancy outcomes in this population, the importance of reproductive outcomes, and the potential emergence of new hazards.

Reaction of cysteine residues with oxidized tyrosine residues mediates cross-linking of photo-oxidized casein proteins

Photo-oxidation of casein proteins is commonplace during milk processing and storage. A major consequence of such light exposure is protein cross-linking and aggregation. Although caseins are key milk components, the nature of the cross-links and the mechanisms involved are poorly characterized, with most previous work having been focused on detecting and quantifying di-tyrosine formed on dimerization of two tyrosine-derived phenoxyl radicals. However, this is only one of a large number of possible cross-links that might be formed. In this study, we have investigated the potential involvement of secondary reactions between oxidized protein side-chains and the thiol group of cysteine (Cys) residues in casein cross-linking. Casein proteins were subjected to photo-oxidation using visible light in the presence of a sensitizer (riboflavin or rose Bengal) and O₂, then incubated with a Cys-containing peptide (glutathione, GSH) or protein (κ-casein), and subsequently analyzed by SDS-PAGE, immunoblotting and LC-MS. Our data indicate that that photo-oxidized (but not parent) caseins react efficiently with the Cys-containing species, likely via Michael addition to quinones formed from tyrosine residues to give glutathionylated species or protein adducts. Thus, oxidized α-casein reacts with native κ-casein to give high molecular mass aggregates. This adduct formation was prevented by alkylation of the Cys thiol group. The cross-link site and the residues involved have been confirmed by liquid chromatography-mass spectrometry (LC-MS) proteomic analysis. Together, these data extend our knowledge of the mechanisms involved in casein oxidation and aggregation.

Oxidative Crosslinking of Peptides and Proteins: Mechanisms of Formation, Detection, Characterization and Quantification

Covalent crosslinks within or between proteins play a key role in determining the structure and function of proteins. Some of these are formed intentionally by either enzymatic or molecular reactions and are critical to normal physiological function. Others are generated as a consequence of exposure to oxidants (radicals, excited states or two-electron species) and other endogenous or external stimuli, or as a result of the actions of a number of enzymes (e.g., oxidases and peroxidases). Increasing evidence indicates that the accumulation of unwanted crosslinks, as is seen in ageing and multiple pathologies, has adverse effects on biological function. In this article, we review the spectrum of crosslinks, both reducible and non-reducible, currently known to be formed on proteins; the mechanisms of their formation; and experimental approaches to the detection, identification and characterization of these species.

Effect of macromolecular crowding on protein oxidation: Consequences on the rate, extent and oxidation pathways

Biological systems are heterogeneous and crowded environments. Such packed milieus are expected to modulate reactions both inside and outside the cell, including protein oxidation. In this work, we explored the effect of macromolecular crowding on the rate and extent of oxidation of Trp and Tyr, in free amino acids, peptides and proteins. These species were chosen as they are readily oxidized and contribute to damage propagation. Dextran was employed as an inert crowding agent, as this polymer decreases the fraction of volume available to other (macro)molecules. Kinetic analysis demonstrated that dextran enhanced the rate of oxidation of free Trp, and peptide Trp, elicited by AAPH-derived peroxyl radicals. For free Trp, the rates of oxidation were 15.0 ± 2.1 and 30.5 ± 3.4 μM min-1 without and with dextran (60 mg mL-1) respectively. Significant increases were also detected for peptide-incorporated Trp. Dextran increased the extent of Trp consumption (up to 2-fold) and induced short chain reactions. In contrast, Tyr oxidation was not affected by the presence of dextran. Studies on proteins, using SDS-PAGE and LC-MS, indicated that oxidation was also affected by crowding, with enhanced amino acid loss (45% for casein), chain reactions and altered extents of oligomer formation. The overall effects of dextran-mediated crowding were however dependent on the protein structure. Overall, these data indicate that molecular crowding, as commonly encountered in biological systems affect the rates, and extents of oxidation, and particularly of Trp residues, illustrating the importance of appropriate choice of in vitro systems to study biological oxidations.

Lifestyle intervention improves Left atrial strain in type 2 diabetes: results from the DIASTOLIC randomised trial

Introduction

Left atrial (LA) strain has been shown to be an independent predictor of cardiovascular events in many conditions and superior to conventional measures of LA function (LA volumes and emptying fraction). The effects of low-energy diet or exercise on cardiovascular function in younger adults with type 2 diabetes (DIASTOLIC) study has previously demonstrated an improvement in left ventricle peak early diastolic strain rate in response to aerobic exercise in patients with type-2 diabetes (T2D). However, the effect of lifestyle intervention on LA function, assessed by cardiac magnetic resonance (CMR) imaging, is unknown.

Methods

The DIASTOLIC study was a prospective, randomised, open-label, blind endpoint trial, that randomised 90 obese participants with T2D (aged 18–65 years) to a 12-week intervention of: (i) routine care, (ii) aerobic exercise training, or (iii) low energy (≈810kcal/day) meal replacement plan (MRP). CMR was performed at baseline and week-12. Images were analysed using Medis v3.1. LA strain (LAS) was assessed using Feature Tracking (QStrain v2.0), corresponding to LA reservoir (LAS-r), conduit (LAS-cd), and booster pump (LAS-bp) using 4- and 2-chamber standard steady-state free precession cine images, and average values calculated. LA emptying fraction (LAEF) was calculated using biplane area-length method (QMass v8.1) for total, passive and active EF.

Results

73 participants with T2D completed the trial and had analysable LA images (28 routine care, 22 exercise and 23 MRP). There was no significant change in CMR measured standard LA volumetric function (LAV/LAEF) and echocardiogram measured LV filling pressures (E/e') in any groups. The routine care arm showed no significant change in body mass index (BMI) or LAS (see Table). In the MRP group, there were significant reductions in BMI (4.8 kg/m2), mean systolic blood pressure (SBP) (13mmHg), and a significant increase in LAS-r and LAS-bp (29.9±7.0 to 32.3±7.0,p=0.036 and 14.6±5.3 to 17.2±3.7,p=0.034). The exercise arm showed a small reduction in BMI (0.8kg/m2), with no significant change in BP or LAS.

Conclusion

There was significant improvement in LAS post-lifestyle intervention in young adults with T2D, despite no change in volumetric measurements. MRP led to weight loss and improved SBP, with associated improved LA filling and contraction.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Institute for Health Research (NIHR) a career development fellowship.

Effect of Plyometric Training and Biological Maturation on Jump and Change of Direction Ability in Female Youth

ABSTRACT

Davies, MJ, Drury, B, Ramirez-Campillo, R, Chaabane, H, and Moran, J. Effect of plyometric training and biological maturation on jump and change of direction ability in female youth. J Strength Cond Res 35(10): 2690-2697, 2021-Biological maturation has been shown to affect male youths' responses to plyometric training (PT). However, to date, no researcher has examined the effect of maturation on the effects of PT in female youth. We undertook the first controlled intervention study to examine this, focusing on adaptive responses to countermovement jump (CMJ), reactive strength index (RSI), and change of direction (COD) performance in groups of female youth divided by maturation status (years from peak height velocity [PHV]). The training program lasted 7 weeks with subjects undertaking 2 sessions of PT per week. In the mid-PHV group, there was a small increase (effect size; 90% confidence interval = 0.40; -0.23 to 1.03) in CMJ performance. No changes were observed in the post-PHV group (0.02; -0.68 to 0.72). For RSI, there was a moderate increase in the mid-PHV group (0.94; 0.29-1.59) with only a trivial increase in the post-PHV group (0.06; -0.65 to 0.76). The intervention exerted no positive effect on COD performance in any group. Plyometric training seems to enhance CMJ and RSI in female youth, although the magnitude of adaptation could be affected by maturation status. A twice-per-week program of multidirectional jumping and hopping, with bilateral and unilateral components, can be used as a preparatory precursor to physical education classes or recreational sport.

Suppressive effect of 1,4-anhydro-4-seleno-D-talitol (SeTal) on atopic dermatitis-like skin lesions in mice through regulation of inflammatory mediators

BACKGROUND

Atopic dermatitis (AD) is a multifactorial chronic inflammatory disease that affects ∼20 % of children and 3% of adults globally and is generally treated by the topical application of steroidal drugs that have undesirable side-effects. The development of alternative therapies is therefore an important objective. The present study investigated the effects of topical treatment with a novel water-soluble selenium-containing carbohydrate derivative (4-anhydro-4-seleno-D-tatitol, SeTal) on the symptoms and inflammatory parameters in an AD mouse model.

METHODS

Mice were sensitized by applying 2,4-dinitrochlorobenzene (DNCB) to their dorsal skin on days 1-3, then further challenged on their ears and dorsal skin on days 14, 17, 20, 23, 26, and 29. SeTal (1 and 2%) or hydrocortisone (1%) was applied topically to the backs of the mice from days 14-29, and skin severity scores and scratching behavior determined on day 30. The mice were euthanized, and their ears and dorsal skin removed to quantify inflammatory parameters, edema, myeloperoxidase (MPO) activity, and AD-associated cytokines (tumor necrosis factor alpha (TNF-α), interleukins (IL)-18, and IL-33).

RESULTS

DNCB treatment induced skin lesions and increased the scratching behavior, ear edema, MPO activity (ear and dorsal skin), and cytokine levels in dorsal skin. Topical application of SeTal improved inflammatory markers (cytokine levels and MPO activity), cutaneous severity scores, and scratching behavior.

CONCLUSION

The efficacy of SeTal was satisfactory in the analyzed parameters, showing similar or better results than hydrocortisone. SeTal appears to be therapeutically advantageous for the treatment and control of AD.

Role of myeloperoxidase and oxidant formation in the extracellular environment in inflammation-induced tissue damage

The heme peroxidase family generates a battery of oxidants both for synthetic purposes, and in the innate immune defence against pathogens. Myeloperoxidase (MPO) is the most promiscuous family member, generating powerful oxidizing species including hypochlorous acid (HOCl). Whilst HOCl formation is important in pathogen removal, this species is also implicated in host tissue damage and multiple inflammatory diseases. Significant oxidant formation and damage occurs extracellularly as a result of MPO release via phagolysosomal leakage, cell lysis, extracellular trap formation, and inappropriate trafficking. MPO binds strongly to extracellular biomolecules including polyanionic glycosaminoglycans, proteoglycans, proteins, and DNA. This localizes MPO and subsequent damage, at least partly, to specific sites and species, including extracellular matrix (ECM) components and plasma proteins/lipoproteins. Biopolymer-bound MPO retains, or has enhanced, catalytic activity, though evidence is also available for non-catalytic effects. These interactions, particularly at cell surfaces and with the ECM/glycocalyx induce cellular dysfunction and altered gene expression. MPO binds with higher affinity to some damaged ECM components, rationalizing its accumulation at sites of inflammation. MPO-damaged biomolecules and fragments act as chemo-attractants and cell activators, and can modulate gene and protein expression in naïve cells, consistent with an increasing cycle of MPO adhesion, activity, damage, and altered cell function at sites of leukocyte infiltration and activation, with subsequent tissue damage and dysfunction. MPO levels are used clinically both diagnostically and prognostically, and there is increasing interest in strategies to prevent MPO-mediated damage; therapeutic aspects are not discussed as these have been reviewed elsewhere.

Diagnosis delayed: health profile differences between women with undiagnosed polycystic ovary syndrome and those with a clinical diagnosis by age 35 years

STUDY QUESTION

Are reproductive, metabolic or psychological health profiles of women with clinically diagnosed polycystic ovary syndrome (PCOS) different from those with undiagnosed PCOS?

SUMMARY ANSWER

Obtaining a clinical diagnosis of PCOS is strongly linked to the experience of fertility problems, but not clinical depression or poor metabolic health, although these were highly prevalent in women with PCOS irrespective of when they were diagnosed.

WHAT IS KNOWN ALREADY

PCOS is an endocrine disorder that is relative common, but heterogeneous in presentation. This may impact on the pathways to diagnosis and timely treatment.

STUDY DESIGN, SIZE, DURATION

A cross-sectional analysis of a community-based cohort of 974 women, established retrospectively when women were around 30 years of age.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In this cohort of women born in Adelaide, South Australia, half of women who met the Rotterdam criteria for PCOS were previously undiagnosed. We compared women with prior clinical diagnosis of PCOS, those diagnosed through participation in this research, and the remainder in the cohort. Sociodemographic characteristics, reproductive, metabolic and psychological health, including medical conditions and medications were considered. Logistic regression was undertaken to identify independent predictors of prior clinical diagnosis.

MAIN RESULTS AND THE ROLE OF CHANCE

There were 56 women with a prior clinical diagnosis of PCOS (5.7%) and a further 64 (6.6%) were undiagnosed until study entry. The great majority of women with a prior diagnosis of PCOS reported having had problems with periods (95%) and excess body hair (63%). Corresponding proportions for women undiagnosed until study participation were slightly lower (81% and 45%, respectively). Although the proportion of women attempting or achieving pregnancy was similar across all groups, those with a prior diagnosis of PCOS were four times more likely to have reported difficulties becoming pregnant than those undiagnosed (odds ratio = 4.05, 95% CI 1.74–9.45) and frequently sought medical assistance. Metabolic problems were higher in both PCOS groups compared to women without PCOS. In both PCOS groups, the prevalence of clinical depression was 50% higher than in those with no PCOS (P = 0.021).

LIMITATIONS, REASONS FOR CAUTION

The number of women who were diagnosed with PCOS both prior to and during the study limited statistical power available to detect modest differences between the PCOS groups. Some women in the group classified as not having PCOS may have remained undiagnosed, but any bias from this source would contribute to more conservative findings.

WIDER IMPLICATIONS OF THE FINDINGS

Findings reinforce the need for early detection of PCOS symptoms from adolescence, ensuring timely diagnosis and appropriate health care. The high prevalence of depression among clinically diagnosed and undiagnosed women with PCOS suggests this is a feature of the condition and supports recent recommendations in the international PCOS guidelines to screen all women with PCOS for depression and anxiety.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by a project grant (2017) from the National Health and Medical Research Council of Australia (NHMRC) Centre for Research Excellence in Polycystic Ovary Syndrome (Grant ID APP1078444). R.C.F. and J.C.A. were supported by Robinson Research Institute Lloyd Cox Career Development Fellowships (2018). Establishment of the cohort was funded by an NHMRC Strategic Award No. 465455, a Career Development Award in Population Health (No. 349548) and the Australian Research Council (Future Fellowship FT100101018) awarded to M.J.D. All authors declared no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

Use of the socio-ecological model to explore factors that influence the implementation of a diabetes structured education programme (EXTEND project) inLilongwe, Malawi and Maputo, Mozambique: a qualitative study

BACKGROUND

Diabetes Self-Management Education and Support (DSMES) programmes are vital for type 2 diabetes mellitus (T2DM) management. However, they are limited in Sub-Saharan Africa (SSA). To address this gap, a DSMES, namedEXTEND was developed in Lilongwe (Malawi) and Maputo (Mozambique). This qualitative study aimed to explore factors that influence the implementation of DSMES in these settings.

METHODS

The Socio-ecological model was applied to explore factors influencing the implementation of DSMES in SSA. Data was analysed using the Framework method and constant comparative techniques. Sixty-six people participated in the study: people with T2DM who participated in the EXTEND programme; healthcare professionals (HCPs), EXTEND educators, EXTEND trainers, and stakeholders.

RESULTS

Our findings indicate that there is a need to develop an integrated and dedicated diabetes services in SSA healthcare systems, incorporating culturally adapted DSMES and tailored diabetes training to all professions involved in diabetes management. Traditional media and the involvement of community leaders were proposed as important elements to help engage and promote DSMES programmes in local communities. During the design and implementation of DSMES, it is important to consider individual and societal barriers to self-care.

CONCLUSION

Findings from this study suggest that multi-faceted factors play a significant role to the implementation of DSMES programmes in LICs. In the future, EXTEND could be incorporated in the development of diabetes training and dedicated diabetes services in SSA healthcare systems, acting as an educational tool for both people with T2DM and HCPs. This project was supported by the Medical Research Council GCRF NCDs Foundation Awards 2016 Development Pathway Funding.

Abstract 2823: Exploring the role of neutrophil myeloperoxidase in lung cancer

The aim of this study is to investigate whether myeloperoxidase, a neutrophil-derived molecule in the tumor microenvironment, can influence tumor growth in lung cancer. Lung cancer is the leading cause of cancer related deaths worldwide. Chronic inflammation plays a key role in lung cancer and some studies point out the role of neutrophils as critical mediators of lung carcinogenesis. In this context, some of the neutrophil granule components have been proposed to contribute to tumor development. One of these molecules is myeloperoxidase. Myeloperoxidase is a heme peroxidase enzyme that generates reactive oxygen/nitrogen species and is most abundantly expressed in neutrophils. Upon neutrophil activation, during acute inflammation or in the tumor microenvironment, MPO is secreted into the extracellular milieu during degranulation and utilizes H2O2 to hypochlorous acid that reacts with surrounding proteins and cell surface molecules and thereby can alter signaling pathways and cell functions. So far, we have found some evidence on myeloperoxidase acting in favor of tumor development. In vivo, LSL-K-ras/MPO-/- mice revealed prolonged survival and reduced tumor burden when compared to LSL-K-ras/MPO+/+ mice. Consistently, in a heterotopic syngeneic tumor mouse model, MPO knockout mice (C57/B6-J/MPO-/-) displayed smaller tumors in comparison to the WT littermates. In vitro, myeloperoxidase is able to bind, internalize and preserve its enzymatic activity in human lung adenocarcinoma A549 cells. Furthermore, A549 cells showed increased proliferation and reduced apoptosis after MPO treatment as well as an enhanced phosphorylation of Akt and Erk proteins. According to our current results, myeloperoxidase may play a role in the development of lung cancer by regulating cancer cell function. Moreover, this project sheds light on the role of neutrophil-derived molecules as key players in the context of tumor growth.

Citation Format: Paulina Valadez-Cosmes, Nejra Cosic, Melanie Kienzl, Kathrin Maitz, Sofia Raftopoulou, A. McGarry Houghton, Akos Heinemann, Michael J. Davies, Julia Kargl. Exploring the role of neutrophil myeloperoxidase in lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2823.

Device-measured physical activity and its association with physical function in adults with type 2 diabetes mellitus

AIM

To quantify how differences in metrics characterizing physical activity and sedentary behaviour in type 2 diabetes are associated with physical function.

METHODS

This analysis included participants' data from the Chronotype of Patients with Type 2 Diabetes and Effect on Glycaemic Control (CODEC) cross-sectional study. Data were stratified into two groups according to their short physical performance battery (SPPB) score (impaired physical function = SPPB < 10 and normal physical function = SPPB ≥ 10). Hand-grip strength, sit-to-stand 60 (STS-60) and the Duke Activity Status Index (DASI) score were used to assess functional capacity, while physical activity metrics were measured with a wrist-worn accelerometer. The associations between physical activity metrics and measures of functional capacity were analysed using generalized linear modelling.

RESULTS

Some 635 adults (median age 66 years, 34% female) were included in this analysis. Overall, 29% of the cohort scored < 10 in the SPPB test indicating impaired physical function. This group spent more time in prolonged sedentary behaviour (600.7 vs. 572.5 min) and undertook less-intense physical activity. Each sd increase in physical activity volume and intensity gradients for those with impaired physical function was associated with 17% more repetitions for STS-60 with similar associations seen for DASI score. Each sd in sedentary time was associated with 15% fewer repetitions in STS-60 and 16% lower DASI score in those with impaired physical function, whereas in normal physical function group it was 2% and 1%, respectively.

CONCLUSIONS

The strength of the associations for physical activity measures and functional capacity were modified by physical function status, with the strongest association seen in those with impaired physical function.

Kinetic assessment of Michael addition reactions of alpha, beta-unsaturated carbonyl compounds to amino acid and protein thiols

Humans have extensive adverse exposure to alpha,beta-unsaturated carbonyl compounds (ABuCs) as these are major toxins in smoke and exhaust fumes, as well as products of lipid peroxidation. In contrast, another ABuC, dimethylfumarate, is used to treat psoriasis and multiple sclerosis. ABuCs undergo Michael adduction with amine, imidazole and thiol groups, with reaction at Cys residues predominating. Here we report rate constants, k₂, for ABuCs (acrolein, crotonaldehyde, dimethylfumarate, cyclohex-1-en-2-one, cyclopent-1-en-2-one) with Cys residues present on N-Ac-Cys, GSH, bovine serum albumin, creatine kinase, papain, glyceraldehyde-3-phosphate dehydrogenase, and both wild-type and the C151S mutant of Keap-1. k₂ values for N-Ac-Cys and GSH vary by > 250-fold, indicating a marked ABuC structure dependence, with acrolein the most reactive. There is also considerable variation in k₂ between protein Cys groups, with these significantly greater than for GSH. A linear inverse correlation for acrolein with the thiol pK_a indicates that the thiolate anion is the reactive species. The modest k₂ for GSH rationalizes the detection of protein adducts of ABuCs in cells. The k₂ values for dimethylfumarate also vary markedly, with the Cys151 residue on Keap-1 being particularly reactive, with the C151S mutant giving a much lower k₂ value. The data for crotonaldehyde, dimethylfumarate, and cyclohex-1-en-2-one show little correlation with the Cys pK_a values, indicating that steric/electronic interactions, rather than Cys ionization are important. These data indicate that protein Cys residues, and particularly Cys151 on Keap-1, react readily with dimethylfumarate, and this may help rationalize the use of this compound as a therapeutic agent.

Oxidation of lysozyme induced by peroxyl radicals involves amino acid modifications, loss of activity, and formation of specific crosslinks

The present work examined the oxidation and crosslinking of the anti-bacterial enzyme lysozyme (Lyso), which is present in multiple biological fluids, and released from the cytoplasmic granules of macrophages and neutrophils at sites of infection and inflammation. It is therefore widely exposed to oxidants including peroxyl radicals (ROO•). We hypothesized that exposure to ROO• would generate specific modifications and inter- and intra-protein crosslinks via radical-radical reactions. Lyso was incubated with AAPH (2,2'-azobis(2-methylpropionamidine) dihydrochloride) as a ROO• source. Enzymatic activity was assessed, while oxidative modifications were detected and quantified using electrophoresis and liquid chromatography (UPLC) with fluorescence or mass detection (MS). Computational models of AAPH-Lyso interactions were developed. Exposure of Lyso to AAPH (10 and 100 mM for 3 h, and 20 mM for 1 h), at 37 °C, decreased enzymatic activity. 20 mM AAPH showed the highest efficiency of Lyso inactivation (1.78 mol of Lyso inactivated per ROO•). Conversion of Met to its sulfoxide, and to a lesser extent, Tyr oxidation to 3,4-dihydroxyphenylalanine and diTyr, were detected by UPLC-MS. Extensive transformation of Trp, involving short chain reactions, to kynurenine, oxindole, hydroxytryptophan, hydroperoxides or di-alcohols, and N-formyl-kynurenine was detected, with Trp62, Trp63 and Trp108 the most affected residues. Interactions of AAPH inside the negatively-charged catalytic pocket of Lyso, with Trp108, Asp52, and Glu35, suggest that Trp108 oxidation mediates, at least partly, Lyso inactivation. Crosslinks between Tyr20-Tyr23 (intra-molecular), and Trp62-Tyr23 (inter-molecular), were detected with both proximity (Tyr20-Tyr23), and chain flexibility (Trp62) appearing to favor the formation of covalent crosslinks.

Association of working shifts, inside and outside of healthcare, with severe COVID-19: an observational study

BACKGROUND

Health and key workers have elevated odds of developing severe COVID-19; it is not known, however, if this is exacerbated in those with irregular work patterns. We aimed to investigate the odds of developing severe COVID-19 in health and shift workers.

METHODS

We included UK Biobank participants in employment or self-employed at baseline (2006-2010) and with linked COVID-19 data to 31st August 2020. Participants were grouped as neither a health worker nor shift worker (reference category) at baseline, health worker only, shift worker only, or both, and associations with severe COVID-19 investigated in logistic regressions.

RESULTS

Of 235,685 participants (81·5% neither health nor shift worker, 1·4% health worker only, 16·9% shift worker only, and 0·3% both), there were 580 (0·25%) cases of severe COVID-19. The odds of severe COVID-19 was higher in health workers (adjusted odds ratio: 2·32 [95% CI: 1·33, 4·05]; shift workers (2·06 [1·72, 2·47]); and in health workers who worked shifts (7·56 [3·86, 14·79]). Being both a health worker and a shift worker had a possible greater impact on the odds of severe COVID-19 in South Asian and Black and African Caribbean ethnicities compared to White individuals.

CONCLUSIONS

Both health and shift work (measured at baseline, 2006-2010) were independently associated with over twice the odds of severe COVID-19 in 2020; the odds were over seven times higher in health workers who work shifts. Vaccinations, therapeutic and preventative options should take into consideration not only health and key worker status but also shift worker status.

Role of myeloperoxidase-derived oxidants in the induction of vascular smooth muscle cell damage

Myeloperoxidase (MPO) is released by activated immune cells and forms the oxidants hypochlorous acid (HOCl) and hypothiocyanous acid (HOSCN) from the competing substrates chloride and thiocyanate. MPO and the overproduction of HOCl are strongly linked with vascular cell dysfunction and inflammation in atherosclerosis. HOCl is highly reactive and causes marked cell dysfunction and death, whereas data with HOSCN are conflicting, and highly dependent on the nature of the cell type. In this study we have examined the reactivity of HOCl and HOSCN with human coronary artery smooth muscle cells (HCASMC), given the key role of this cell type in maintaining vascular function. HOCl reacts rapidly with the cells, resulting in extensive cell death by both necrosis and apoptosis, and increased levels of intracellular calcium. In contrast, HOSCN reacts more slowly, with cell death occurring only after prolonged incubation, and in the absence of the accumulation of intracellular calcium. Exposure of HCASMC to HOCl also influences mitochondrial respiration, decreases glycolysis, lactate release, the production of ATP, cellular thiols and glutathione levels. These changes occurred to varying extents on exposure of the cells to HOSCN, where evidence was also obtained for the reversible modification of cellular thiols. HOCl also induced alterations in the mRNA expression of multiple inflammatory and phenotypic genes. Interestingly, the extent and nature of these changes was highly dependent on the specific cell donor used, with more marked effects observed in cells isolated from diseased compared to healthy vessels. Overall, these data provide new insight into pathways promoting vascular dysfunction during chronic inflammation, support the use of thiocyanate as a means to modulate MPO-induced cellular damage in atherosclerosis.

M. jannaschii FtsZ, a key protein in bacterial cell division, is inactivated by peroxyl radical-mediated methionine oxidation

Oxidation and inactivation of FtsZ is of interest due to the key role of this protein in bacterial cell division. In the present work, we studied peroxyl radical (from AAPH, 2,2'-azobis(2-methylpropionamidine)dihydrochloride) mediated oxidation of the highly stable FtsZ protein (MjFtsZ) from M. jannaschii, a thermophilic microorganism. MjFtsZ contains eleven Met, and single Tyr and Trp residues which would be expected to be susceptible to oxidation. We hypothesized that exposure of MjFtsZ to AAPH-derived radicals would induce Met oxidation, and cross-linking (via di-Tyr and di-Trp formation), with concomitant loss of its functional polymerization and depolymerization (GTPase) activities. Solutions containing MjFtsZ and AAPH (10 or 100 mM) were incubated at 37 °C for 3 h. Polymerization/depolymerization were assessed by light scattering, while changes in mass were analyzed by SDS-PAGE. Amino acid consumption was quantified by HPLC with fluorescence detection, or direct fluorescence (Trp). Oxidation products and modifications at individual Met residues were quantified by UPLC with mass detection. Oxidation inhibited polymerization-depolymerization activity, and yielded low levels of irreversible protein dimers. With 10 mM AAPH only Trp and Met were consumed giving di-alcohols, kynurenine and di-Trp (from Trp) and the sulfoxide (from Met). With 100 mM AAPH low levels of Tyr oxidation (but not di-Tyr formation) were also observed. Correlation with the functional analyses indicates that Met oxidation, and particularly Met164 is the key driver of MjFtsZ inactivation, probably as a result of the position of this residue at the protein-protein interface of longitudinal interactions and in close proximity to the GTP binding site.

Efficacy and safety of adding sotagliflozin, a dual sodium-glucose co-transporter (SGLT)1 and SGLT2 inhibitor, to optimized insulin therapy in adults with type 1 diabetes and baseline body mass index ≥ 27 kg/m2

Sotagliflozin, a dual sodium-glucose co-transporter (SGLT)1/SGLT2 inhibitor, is currently approved in Europe as an adjunct to optimal insulin therapy in adults with type 1 diabetes (T1D) and a body mass index (BMI) ≥ 27 kg/m² . In this post hoc analysis, efficacy at 24 weeks and safety at 52 weeks from pooled phase 3 clinical trials were evaluated in patients with baseline BMI ≥ 27 kg/m² . Sotagliflozin 200 mg and 400 mg added to insulin reduced glycated haemoglobin level and increased time in range assessed by continuous glucose monitoring versus placebo and also reduced body weight and systolic blood pressure. Differences in efficacy endpoints between sotagliflozin and placebo tended to be greater among patients with BMI ≥ 27 kg/m² compared to those with baseline BMI < 27 kg/m² . Consistent with published results for the entire population, fewer severe hypoglycaemia and documented hypoglycaemia ≤3.1 mmol/L events and a higher incidence of diabetic ketoacidosis occurred with sotagliflozin versus placebo in patients with BMI ≥ 27 kg/m² . Sotagliflozin as an adjunct to optimized insulin therapy in overweight/obese patients with T1D addressed some unmet needs and may help achieve optimal glycaemic control, mitigating weight gain without increasing hypoglycaemia risk in this high-risk population.