Cardiovascular disease in spondyloarthritis: a narrative review of risk factors and the effect of treatments.

PURPOSE OF REVIEW: This review summarizes the recent evidence available regarding the epidemiology of cardiovascular disease in spondyloarthritis (SpA), including the effect of disease modifying drugs on cardiovascular risk. RECENT FINDINGS: People with SpA suffer from an increased risk of cardiovascular disease compared to the general population. This elevated risk is explained by the high prevalence of traditional cardiovascular risk factors and inflammation from disease activity leading to endothelial dysfunction and accelerated atherosclerosis. Consequently, the American College of Cardiology/American Heart Association and the European League Against Rheumatism recommend enhanced cardiovascular risk screening in SpA patients. There is evidence from observational studies that methotrexate and tumor necrosis factor inhibitors reduce the risk of cardiovascular events in SpA. Unlike what is observed in the general population, the use of nonsteroidal anti-inflammatory drugs does not appear to increase cardiovascular disease risk in SpA. SUMMARY: Cardiovascular diseases are increasingly recognized in patients suffering from SpA, especially axial SpA and psoriatic arthritis. Cardiovascular diseases can cause significant morbidity, mortality, and add to the overall disease burden. Disease modifying drugs may mitigate some of the cardiovascular risk; however, a multidisciplinary team is needed to monitor patients and improve cardiovascular health status.

Which Educational Topics and Smartphone App Functions Are Prioritized by US Patients With Rheumatic and Musculoskeletal Diseases? A Mixed-Methods Study.

OBJECTIVE: We sought to identify (1) what types of information US adults with rheumatic and musculoskeletal diseases (RMD) perceive as most important to know about their disease, and (2) what functions they would use in an RMD-specific smartphone app. METHODS: Nominal groups with patients with RMD were conducted using online tools to generate a list of needed educational topics. Based on nominal group results, a survey with final educational items was administered online, along with questions about desired functions of a smartphone app for RMD and wearable use, to patients within a large community rheumatology practice-based research network and the PatientSpot registry. Chi-square tests and multivariate regression models were used to determine differences in priorities between groups of respondents with rheumatic inflammatory conditions (RICs) and osteoarthritis (OA), and possible associations. RESULTS: At least 80% of respondents considered finding a rheumatologist, understanding tests and medications, and quickly recognizing and communicating symptoms to doctors as extremely important educational topics. The highest-ranked topic for both RIC and OA groups was "knowing when the medication is not working." The app functions that most respondents considered useful were viewing laboratory results, recording symptoms to share with their rheumatology provider, and recording symptoms (eg, pain, fatigue) or disease flares for health tracking over time. Approximately one-third of respondents owned and regularly used a wearable activity tracker. CONCLUSION: People with RMD prioritized information about laboratory test results, medications, and disease and symptom monitoring, which can be used to create educational and digital tools that support patients during their disease journey.

Sociodemographic profiles and organ damage accural in the Black Women's Experience Living with Lupus study.

OBJECTIVE: Black/African American women with systemic lupus erythematosus (SLE) experience greater organ damage and at younger ages than white women. The objective of this study was to advance research on SLE inequities by identifying sociodemographic risk profiles associated with organ damage accrual specifically among Black/African American women. METHODS: Latent profile analysis was conducted among 438 Black/African American women with SLE living in Atlanta, GA and enrolled in the Black Women's Experiences Living with Lupus (BeWELL) Study (May 2015 to April 2017). Proportional hazard and Poisson regression models examined prospective associations between sociodemographic profiles and the timing and degree of organ damage accrual over 2 years. RESULTS: Four profiles emerged: (1) "Younger/Lower SES with Uncontrolled SLE" (44.8%), (2) "Older/Lower SES with Uncontrolled SLE" (23.3%), (3) "Mid-SES with Controlled SLE" (19.6%), and (4) "Higher SES with Controlled SLE" (11.2%). Approximately 42% of participants experienced new organ damage during the follow-up period. Proportional hazard models indicated that "Older/Lower SES with Uncontrolled SLE" participants were at greatest risk of new organ damage (HR = 2.41; 95% CI = 1.39, 4.19), followed by "Younger/Lower SES with Uncontrolled SLE" participants (HR = 1.56; 95% CI = 0.92, 2.67), compared to those in the "Higher SES with Controlled SLE" profile. Poisson regression models revealed that these two groups also exhibited greater organ damage accrual (b = 0.98, SE = 0.24, 95% CI = 0.52, 1.44 and b = 0.72, SE = 0.23, 95% CI = 0.27, 1.17, respectively). CONCLUSIONS: Black/African American women with fewer socioeconomic resources and uncontrolled SLE are at greatest risk for increasing disease severity over time. Social inequities likely contribute to racial inequities in SLE progression.

The Off-Target Cardioprotective Mechanisms of Sodium-Glucose Cotransporter 2 Inhibitors: An Overview.

Sodium-glucose cotransporter 2 inhibitors (SGLT2i), a novel class of glucose-lowering drugs, have revolutionized the management of heart failure with reduced and preserved ejection fraction, regardless of the presence of diabetes, and are currently incorporated in the heart failure guidelines. While these drugs have consistently demonstrated their ability to decrease heart failure hospitalizations in several landmark clinical trials, their cardioprotective effects are far from having been completely elucidated. In the past decade, a growing body of experimental research has sought to address the molecular and cellular mechanisms of SGLT2i in order to provide a better understanding of the off-target acute and chronic cardiac benefits, beyond the on-target renal effect responsible for blood glucose reduction. The present narrative review addresses the direct cardioprotective effects of SGLT2i, delving into the off-target mechanisms of the drugs currently approved for heart failure therapy, and provides insights into future perspectives.

Incident racial discrimination predicts elevated C-Reactive protein in the Black Women's experiences Living with Lupus (BeWELL) study.

INTRODUCTION: Racial discrimination is a distinct health threat that increases disease risk among Black Americans. Psychosocial stress may compromise health through inflammatory mechanisms. This study examines incident experiences of racial discrimination and changes in the inflammatory biomarker C-reactive protein (CRP) over a two-year period among Black women with systemic lupus erythematosus (SLE)-an inflammatory autoimmune disease sensitive to psychosocial stress and characterized by stark racial inequities in outcomes. METHODS: Data are from the Black Women's Experiences Living with Lupus (BeWELL) Study. Participants (n = 380) from metropolitan Atlanta, Georgia were enrolled from April 2015 to May 2017. Incident racial discrimination was assessed bi-annually via self-report using the Experiences of Discrimination measure. CRP was assessed annually over a two-year period. Latent change score analyses modeled longitudinal within-person associations between incident racial discrimination and change in log-transformed CRP from baseline to Year 2. RESULTS: Incident experiences of racial discrimination were associated with elevated log-CRP across the two-year study period (b = 0.039, SE = 0.017, 95% CI: 0.006, 0.071). For each domain of incident racial discrimination experienced, CRP increased 3.98%. CONCLUSION: This study contributes to growing evidence on the biological consequences of racism and is the first to document an association between incident racial discrimination and changes in inflammation among Black women with SLE. Racial inequities in SLE outcomes and other diseases driven by inflammatory pathways may be explained in part through experiences of racial discrimination.

Healthcare disparities in telemedicine for rheumatology care.

PURPOSE OF REVIEW: We summarize the recent literature published in the last 2 years on healthcare disparities observed in the delivery of rheumatology care by telemedicine. We highlight recent research dissecting the underpinnings of healthcare disparities and identify potentially modifiable contributing factors. RECENT FINDINGS: The COVID-19 pandemic has had major impacts on care delivery and has led to a pronounced increase in telemedicine use in rheumatology practice. Telemedicine services are disproportionately underutilized by racial/ethnic minority groups and among patients with lower socioeconomic status. Disparities in telemedicine access and use among vulnerable populations threatens to exacerbate existing outcome inequalities affecting people with rheumatic disease. SUMMARY: Telemedicine has the potential to expand rheumatology services by reaching traditionally underserved communities. However, some areas lack the infrastructure and technology to engage in telemedicine. Addressing health equity and the digital divide may help foster more inclusive telemedicine care.

Integration of stakeholder engagement from development to dissemination in genomic medicine research: Approaches and outcomes from the CSER Consortium.

PURPOSE: There is a critical need for genomic medicine research that reflects and benefits socioeconomically and ancestrally diverse populations. However, disparities in research populations persist, highlighting that traditional study designs and materials may be insufficient or inaccessible to all groups. New approaches can be gained through collaborations with patient/community stakeholders. Although some benefits of stakeholder engagement are recognized, routine incorporation into the design and implementation of genomics research has yet to be realized. METHODS: The National Institutes of Health-funded Clinical Sequencing Evidence-Generating Research (CSER) consortium required stakeholder engagement as a dedicated project component. Each CSER project planned and carried out stakeholder engagement activities with differing goals and expected outcomes. Examples were curated from each project to highlight engagement strategies and outcomes throughout the research lifecycle from development through dissemination. RESULTS: Projects tailored strategies to individual study needs, logistical constraints, and other challenges. Lessons learned include starting early with engagement efforts across project stakeholder groups and planned flexibility to enable adaptations throughout the project lifecycle. CONCLUSION: Each CSER project used more than 1 approach to engage with relevant stakeholders, resulting in numerous adaptations and tremendous value added throughout the full research lifecycle. Incorporation of community stakeholder insight improves the outcomes and relevance of genomic medicine research.

Genetic influences on susceptibility to rheumatoid arthritis in African-Americans.

Large meta-analyses of rheumatoid arthritis (RA) susceptibility in European (EUR) and East Asian (EAS) populations have identified >100 RA risk loci, but genome-wide studies of RA in African-Americans (AAs) are absent. To address this disparity, we performed an analysis of 916 AA RA patients and 1392 controls and aggregated our data with genotyping data from >100 000 EUR and Asian RA patients and controls. We identified two novel risk loci that appear to be specific to AAs: GPC5 and RBFOX1 (PAA < 5 × 10-9). Most RA risk loci are shared across different ethnicities, but among discordant loci, we observed strong enrichment of variants having large effect sizes. We found strong evidence of effect concordance for only 3 of the 21 largest effect index variants in EURs. We used the trans-ethnic fine-mapping algorithm PAINTOR3 to prioritize risk variants in >90 RA risk loci. Addition of AA data to those of EUR and EAS descent enabled identification of seven novel high-confidence candidate pathogenic variants (defined by posterior probability > 0.8). In summary, our trans-ethnic analyses are the first to include AAs, identified several new RA risk loci and point to candidate pathogenic variants that may underlie this common autoimmune disease. These findings may lead to better ways to diagnose or stratify treatment approaches in RA.

Characteristics associated with hospitalisation for COVID-19 in people with rheumatic disease: data from the COVID-19 Global Rheumatology Alliance physician-reported registry.

OBJECTIVES: COVID-19 outcomes in people with rheumatic diseases remain poorly understood. The aim was to examine demographic and clinical factors associated with COVID-19 hospitalisation status in people with rheumatic disease. METHODS: Case series of individuals with rheumatic disease and COVID-19 from the COVID-19 Global Rheumatology Alliance registry: 24 March 2020 to 20 April 2020. Multivariable logistic regression was used to estimate ORs and 95% CIs of hospitalisation. Age, sex, smoking status, rheumatic disease diagnosis, comorbidities and rheumatic disease medications taken immediately prior to infection were analysed. RESULTS: A total of 600 cases from 40 countries were included. Nearly half of the cases were hospitalised (277, 46%) and 55 (9%) died. In multivariable-adjusted models, prednisone dose ≥10 mg/day was associated with higher odds of hospitalisation (OR 2.05, 95% CI 1.06 to 3.96). Use of conventional disease-modifying antirheumatic drug (DMARD) alone or in combination with biologics/Janus Kinase inhibitors was not associated with hospitalisation (OR 1.23, 95% CI 0.70 to 2.17 and OR 0.74, 95% CI 0.37 to 1.46, respectively). Non-steroidal anti-inflammatory drug (NSAID) use was not associated with hospitalisation status (OR 0.64, 95% CI 0.39 to 1.06). Tumour necrosis factor inhibitor (anti-TNF) use was associated with a reduced odds of hospitalisation (OR 0.40, 95% CI 0.19 to 0.81), while no association with antimalarial use (OR 0.94, 95% CI 0.57 to 1.57) was observed. CONCLUSIONS: We found that glucocorticoid exposure of ≥10 mg/day is associated with a higher odds of hospitalisation and anti-TNF with a decreased odds of hospitalisation in patients with rheumatic disease. Neither exposure to DMARDs nor NSAIDs were associated with increased odds of hospitalisation.

Pragmatic Clinical Trials in Osteoporosis.

PURPOSE OF REVIEW: In this review, we present the application of pragmatic clinical trials for evaluating interventions in osteoporosis, and we discuss methodological considerations for designing and conducting a pragmatic clinical trial compared with a classical randomized clinical trial. RECENT FINDINGS: Pragmatic clinical trials are a popular study design testing effectiveness of health interventions and are intended to address the limitations associated with traditional explanatory randomized clinical trials testing efficacy of interventions. To date, only few pragmatic clinical trials have been conducted in osteoporosis. Pragmatic clinical trials are conducted under routine clinical practice setting and are intended to inform policy makers and clinical decisions. Osteoporosis is a chronic disease well-suited to this particular study design given the existence of a clear and specific natural endpoint, namely fracture occurrence, and the availability of several treatments to prevent fractures.

Advancing the Science and Practice of Medication Adherence.

Medication adherence remains a significant unmet challenge for optimizing patient outcomes. Recent advances in the conceptualization, measurement, and support of medication adherence offer fresh opportunities to make a meaningful impact on adherence-related behavior and outcomes. These advances emphasize the multifaceted and dynamic nature of medication adherence, provide novel methods for monitoring medication adherence in clinical care, and articulate a set of multilevel strategies to more effectively improve and sustain medication adherence. Here, we offer recommendations for how clinicians can better engage with, and benefit from, these innovations to improve patient medication adherence and associated treatment outcomes.

Use of Scribes for Documentation Assistance in Rheumatology and Endocrinology Clinics: Impact on Clinic Workflow and Patient and Physician Satisfaction.

BACKGROUND/OBJECTIVE: The aim of this study was to examine the impact of utilizing medical scribes on clinic workflow, physician professional satisfaction, and patient satisfaction in rheumatology and endocrinology clinics. METHODS: We conducted a within-practice pilot study of medical scribes that included a 6-week intervention phase (documentation assistance by medical scribes) followed by a control phase (usual documentation with no assistance) in outpatient rheumatology and endocrinology clinics at an academic medical center. We evaluated the following outcomes: physician professional satisfaction (range, 5-25, with higher values denoting higher satisfaction), autonomy (range, 4-16, with higher values denoting higher autonomy), perception of clinic workflow (range, 1 = calm, 5 = chaotic), and patient satisfaction (5-point Likert item, anchors: strongly agree, strongly disagree). RESULTS: Six physicians, including 3 rheumatologists and 3 endocrinologists, and 496 patients nested within their practices participated. The use of a medical scribe was not associated with physician professional satisfaction (18.17 [SD, 2.9] vs. 17.83 [SD, 1.94], not statistically significant), perception of clinic workflow (2.50 [SD, 0.84] vs. 3.17 [SD, 0.75], not statistically significant), or autonomy (8.67 [SD, 3.44] vs. 8.83 [SD, 3.06], not statistically significant). Physicians had an overall favorable view of the medical scribes program and perceived that documentation support provided by scribes was useful and easy to use and had a positive impact on their clinic workflow. Patient satisfaction was high during the intervention phase (99.4% strongly agree/agree) but not significantly different than in the control phase. CONCLUSIONS: Rheumatologists, endocrinologists, and their patients had consistently positive views regarding the use of a medical scribe without an observed negative effect on clinic workflow in outpatient clinics.

Children's satisfaction and dissatisfaction with pain management in a Pediatric Emergency Department.

OBJECTIVE: To understand children's satisfaction and dissatisfaction with pain management in the pediatric emergency department. METHOD: Exploratory-descriptive qualitative study performed with children between 6 and 12 years of age and use of semi-structured interviews and thematic analysis of data. RESULTS: Nineteen children were interviewed. The results were organized in two themes: Theme 1 - Satisfaction perceived by children regarding pain management, which included three subthemes, namely: Priority care and quick pain relief, Basic needs met and Embracement by the team; and Theme 2 - Dissatisfaction perceived by children regarding pain management, which included three subthemes: Painful procedures, Uncomfortable environment and Delay in pain relief. CONCLUSION: Children's satisfaction with pain management was observed to be much more than pain relief or priority service, and also included the pediatric emergency department environment and embracement by the team. Care should be directed to children's singularities, that is, a care built from the understanding of the experience from children's point of view.

Dense Genotyping of Immune-Related Regions Identifies Loci for Rheumatoid Arthritis Risk and Damage in African Americans.

Over 100 risk loci for rheumatoid arthritis (RA) have been identified in individuals of European and Asian descent, but the genetic basis for RA in African Americans is less well understood. We genotyped 610 African Americans with autoantibody positive RA and 933 African American controls on the ImmunoChip (iChip) array. Using multivariable regression we evaluated the association between iChip markers and the risk of RA and radiographic severity. The single nucleotide polymorphism (SNP) rs1964995 (OR = 1.97, p = 1.28 × 10-15) near HLA-DRB1 was the most strongly associated risk SNP for RA susceptibility; SNPs in AFF3, TNFSF11, and TNFSF18 loci were suggestively associated (10-4 < p < 3.1 × 10-6). Trans-ethnic fine mapping of AFF3 identified a 90% credible set containing previously studied variants including rs9653442, rs7608424, and rs6712515 as well as the novel candidate variant rs11681966; several of these likely influence AFF3 gene expression level. Variants in TNFRSF9, CTLA4, IL2RA, C5/TRAF1, and ETS1 - but no variants within the major histocompatibility complex - were associated with RA radiographic severity. Conditional regression and pairwise linkage disequilibrium (LD) analyses suggest that additional pathogenic variants may be found in ETS1 and IL2RA beyond those found in other ethnicities. In summary, we use the dense genotyping of the iChip array and unique LD structure of African Americans to validate known risk loci for RA susceptibility and radiographic severity, and to better characterize the associations of AFF3, ETS1, and IL2RA.

The effect of purinergic signaling via the P2Y11 receptor on vascular function in a rat model of acute inflammation.

There is a growing body of evidence pointing to the role of purinergic signaling in the development and progression of various conditions that have inflammation as a common pathogenetic denominator. The aim of the present study was to assess the involvement of P2Y11 purinergic receptors in the regulation of vascular function in aortic segments obtained using an experimental model of acute inflammation, the lipopolysaccharide (LPS, 8 mg/kg, i.p)-treated rats. Twelve hours after LPS administration, thoracic aortas were isolated and used for studies of vascular reactivity in the organ bath and for the measurement of reactive oxygen species (ROS) generation, respectively. LPS treatment significantly increased contractility to phenylephrine and attenuated the endothelium-dependent relaxation of the vascular segments in response to acetylcholine; an increased production of hydrogen peroxide (H2O2) was also recorded. The P2Y11 activator, NF546, decreased the LPS-induced aortic H2O2 release and partially normalized the vasomotor function, namely reduced contractility and improved relaxation. The effect was abolished by co-treatment with the P2Y11 inhibitor, NF340, and also after endothelium denudation. Importantly, NF546 did not elicit an antioxidant effect by acting as a H2O2 scavenger, suggesting that the beneficial outcome of this treatment on the vasculature is the consequence of P2Y11 stimulation. In conclusion, purinergic P2Y11 receptors stimulation improves vascular function and mitigates oxidative stress in the setting of acute systemic inflammation, revealing salutary effects and therapeutic potential in pathologies associated with endothelial dysfunction.

Methylene blue improves mitochondrial respiration and decreases oxidative stress in a substrate-dependent manner in diabetic rat hearts.

Diabetic cardiomyopathy has been systematically associated with compromised mitochondrial energetics and increased generation of reactive oxygen species (ROS) that underlie its progression to heart failure. Methylene blue is a redox drug with reported protective effects mainly on brain mitochondria. The purpose of the present study was to characterize the effects of acute administration of methylene blue on mitochondrial respiration, H2O2 production, and calcium sensitivity in rat heart mitochondria isolated from healthy and 2 months (streptozotocin-induced) diabetic rats. Mitochondrial respiratory function was assessed by high-resolution respirometry. H2O2 production and calcium retention capacity were measured spectrofluorimetrically. The addition of methylene blue (0.1 µmol·L-1) elicited an increase in oxygen consumption of mitochondria energized with complex I and II substrates in both normal and diseased mitochondria. Interestingly, methylene blue elicited a significant increase in H2O2 release in the presence of complex I substrates (glutamate and malate), but had an opposite effect in mitochondria energized with complex II substrate (succinate). No changes in the calcium retention capacity of healthy or diabetic mitochondria were found in the presence of methylene blue. In conclusion, in cardiac mitochondria isolated from diabetic and nondiabetic rat hearts, methylene blue improved respiratory function and elicited a dichotomic, substrate-dependent effect on ROS production.

Increased pretreatment serum IFN-ß/α ratio predicts non-response to tumour necrosis factor α inhibition in rheumatoid arthritis.

OBJECTIVE: Studies suggest that circulating type I interferon (IFN) may predict response to biological agents in rheumatoid arthritis (RA). Prediction of response prior to initiating therapy would represent a major advancement. METHODS: We studied sera from a test set of 32 patients with RA from the Auto-immune Biomarkers Collaborative Network Consortium and a validation set of 92 patients with RA from the Treatment Efficacy and Toxicity in Rheumatoid Arthritis Database and Repository registry. The test set included those with good response or no response to tumour necrosis factor (TNF) inhibitors at 14 weeks by European League Against Rheumatism criteria. The validation set included subjects with good, moderate or no response at 12 weeks. Total serum type I IFN activity, IFN-α and IFN-ß activity were measured using a functional reporter cell assay. RESULTS: In the test set, an increased ratio of IFN-ß to IFN-α (IFN-ß/α activity ratio) in pretreatment serum associated with lack of response to TNF inhibition (p=0.013). Anti-cyclic citrullinated peptide antibody titre and class of TNF inhibitor did not influence this relationship. A receiver-operator curve supported a ratio of 1.3 as the optimal cut-off. In the validation set, subjects with an IFN-ß/α activity ratio >1.3 were significantly more likely to have non-response than good response (OR=6.67, p=0.018). The test had 77% specificity and 45% sensitivity for prediction of non-response compared with moderate or good response. Meta-analysis of test and validation sets confirmed strong predictive capacity of IFN-ß/α activity ratio (p=0.005). CONCLUSIONS: Increased pretreatment serum IFN-ß/α ratio strongly associated with non-response to TNF inhibition. This study supports further investigation of serum type I IFN in predicting outcome of TNF inhibition in RA.

Simple regression for correcting ΔCt bias in RT-qPCR low-density array data normalization.

BACKGROUND: Reverse transcription quantitative PCR (RT-qPCR) is considered the gold standard for quantifying relative gene expression. Normalization of RT-qPCR data is commonly achieved by subtracting the Ct values of the internal reference genes from the Ct values of the target genes to obtain ΔCt. ΔCt values are then used to derive ΔΔCt when compared to a control group or to conduct further statistical analysis. RESULTS: We examined two rheumatoid arthritis RT-qPCR low density array datasets and found that this normalization method introduces substantial bias due to differences in PCR amplification efficiency among genes. This bias results in undesirable correlations between target genes and reference genes, which affect the estimation of fold changes and the tests for differentially expressed genes. Similar biases were also found in multiple public mRNA and miRNA RT-qPCR array datasets we analysed. We propose to regress the Ct values of the target genes onto those of the reference genes to obtain regression coefficients, which are then used to adjust the reference gene Ct values before calculating ΔCt. CONCLUSIONS: The per-gene regression method effectively removes the ΔCt bias. This method can be applied to both low density RT-qPCR arrays and individual RT-qPCR assays.

Monoamine oxidases are novel sources of cardiovascular oxidative stress in experimental diabetes.

Diabetes mellitus (DM) is widely recognized as the most severe metabolic disease associated with increased cardiovascular morbidity and mortality. The generation of reactive oxygen species (ROS) is a major event causally linked to the development of cardiovascular complications throughout the evolution of DM. Recently, monoamine oxidases (MAOs) at the outer mitochondrial membrane, with 2 isoforms, MAO-A and MAO-B, have emerged as novel sources of constant hydrogen peroxide (H2O2) production in the cardiovascular system via the oxidative deamination of biogenic amines and neurotransmitters. Whether MAOs are mediators of endothelial dysfunction in DM is unknown, and so we studied this in a streptozotocin-induced rat model of diabetes. MAO expression (mRNA and protein) was increased in both arterial samples and hearts isolated from the diabetic animals. Also, H2O2 production (ferrous oxidation - xylenol orange assay) in aortic samples was significantly increased, together with an impairment of endothelium-dependent relaxation (organ-bath studies). MAO inhibitors (clorgyline and selegiline) attenuated ROS production by 50% and partially normalized the endothelium-dependent relaxation in diseased vessels. In conclusion, MAOs, in particular the MAO-B isoform, are induced in aortas and hearts in the streptozotocin-induced diabetic rat model and contribute, via the generation of H2O2, to the endothelial dysfunction associated with experimental diabetes.

Modulation of mitochondrial respiratory function and ROS production by novel benzopyran analogues.

A substantial body of evidence indicates that pharmacological activation of mitochondrial ATP-sensitive potassium channels (mKATP) in the heart is protective in conditions associated with ischemia/reperfusion injury. Several mechanisms have been postulated to be responsible for cardioprotection, including the modulation of mitochondrial respiratory function. The aim of the present study was to characterize the dose-dependent effects of novel synthetic benzopyran analogues, derived from a BMS-191095, a selective mKATP opener, on mitochondrial respiration and reactive oxygen species (ROS) production in isolated rat heart mitochondria. Mitochondrial respiratory function was assessed by high-resolution respirometry, and H2O2 production was measured by the Amplex Red fluorescence assay. Four compounds, namely KL-1487, KL-1492, KL-1495, and KL-1507, applied in increasing concentrations (50, 75, 100, and 150 µmol/L, respectively) were investigated. When added in the last two concentrations, all compounds significantly increased State 2 and 4 respiratory rates, an effect that was not abolished by 5-hydroxydecanoate (5-HD, 100 µmol/L), the classic mKATP inhibitor. The highest concentration also elicited an important decrease of the oxidative phosphorylation in a K(+) independent manner. Both concentrations of 100 and 150 µmol/L for KL-1487, KL-1492, and KL-1495, and the concentration of 150 µmol/L for KL-1507, respectively, mitigated the mitochondrial H2O2 release. In isolated rat heart mitochondria, the novel benzopyran analogues act as protonophoric uncouplers of oxidative phosphorylation and decrease the generation of reactive oxygen species in a dose-dependent manner.