Redox Pathogenesis in Rheumatic Diseases.

Despite being some of the most anecdotally well-known roads to pathogenesis, the mechanisms governing autoimmune rheumatic diseases are not yet fully understood. The overactivation of the cellular immune system and the characteristic development of autoantibodies have been linked to oxidative stress. Typical clinical manifestations, such as joint swelling and deformities and inflammation of the skin and internal organs, have also been connected directly or indirectly to redox mechanisms. The differences in generation and restraint of oxidative stress provide compelling evidence for the broad variety in pathology among rheumatic diseases and explain some of the common triggers and discordant manifestations in these diseases. Growing evidence of redox mechanisms in pathogenesis has provided a broad array of new potential therapeutic targets. Here, we explore the mechanisms by which oxidative stress is generated, explore its roles in autoimmunity and end-organ damage, and discuss how individual rheumatic diseases exhibit unique features that offer targets for therapeutic interventions.

Mitral valve surgery in patients with Marfan syndrome.

OBJECTIVE: To review the pathology of the mitral valve (MV) and long-term outcomes of surgery in patients with Marfan syndrome (MFS). PATIENTS AND METHODS: From 1988 through 2020, 60 patients with MFS had surgery to correct mitral regurgitation (MR): 19 had isolated MV surgery, 32 had combined MV and aortic root surgery, and 9 had MV surgery after aortic root surgery. Follow-up was complete for a median of 16.1 years. RESULTS: MV pathology was myxomatous degeneration in all patients and of advanced degree in 78.6% with bileaflet prolapse in 65.5%, mitral annulus disjunction in 57.5%, and mitral annulus calcification in 8.2% of patients. The MV was repaired in 47 patients and replaced in 13. Kaplan-Meier estimates of cumulative mortality at 20 years 21.3% for all patients, 6.7% after MV repair, and 57.8% after replacement (P < .001). MV reoperations were performed in 5 patients: 2 after repair and 3 after replacement. The cumulative incidence rate of reoperations on the MV was 3.8% at 10 years and 11.0% at 20 years in the entire cohort. Among 47 patients who had MV repair, moderate MR developed in 11 patients and severe in 2. Both patients with severe MR underwent MV reoperation. The cumulative incidence rate of recurrent moderate or severe MR after MV repair was 20.4% at 10 years, and 36.5% at 20 years. CONCLUSIONS: MV repair was associated with better survival than MV replacement, but recurrent MR after repair occurred in approximately one-third of the patients at 20 years after surgery.

Rab4A-directed endosome traffic shapes pro-inflammatory mitochondrial metabolism in T cells via mitophagy, CD98 expression, and kynurenine-sensitive mTOR activation.

Activation of the mechanistic target of rapamycin (mTOR) is a key metabolic checkpoint of pro-inflammatory T-cell development that contributes to the pathogenesis of autoimmune diseases, such as systemic lupus erythematosus (SLE), however, the underlying mechanisms remain poorly understood. Here, we identify a functional role for Rab4A-directed endosome traffic in CD98 receptor recycling, mTOR activation, and accumulation of mitochondria that connect metabolic pathways with immune cell lineage development and lupus pathogenesis. Based on integrated analyses of gene expression, receptor traffic, and stable isotope tracing of metabolic pathways, constitutively active Rab4AQ72L exerts cell type-specific control over metabolic networks, dominantly impacting CD98-dependent kynurenine production, mTOR activation, mitochondrial electron transport and flux through the tricarboxylic acid cycle and thus expands CD4+ and CD3+CD4-CD8- double-negative T cells over CD8+ T cells, enhancing B cell activation, plasma cell development, antinuclear and antiphospholipid autoantibody production, and glomerulonephritis in lupus-prone mice. Rab4A deletion in T cells and pharmacological mTOR blockade restrain CD98 expression, mitochondrial metabolism and lineage skewing and attenuate glomerulonephritis. This study identifies Rab4A-directed endosome traffic as a multilevel regulator of T cell lineage specification during lupus pathogenesis.

Cardiovascular Events After Aortic Root Repair in Patients With Marfan Syndrome.

BACKGROUND: The usefulness of aortic valve sparing operations to treat aortic root aneurysm in patients with Marfan syndrome (MS) remains controversial. OBJECTIVES: The purpose of this study was to evaluate the occurrence of cardiovascular events in patients with MS who have undergone valve-preserving aortic root replacement. METHODS: Patients with MS who had aortic valve sparing operations (reimplantation of the aortic valve or remodeling of the aortic root) from 1988 through 2019 were followed prospectively for a median of 14 years. Pertinent data from clinical, echocardiographic, computed tomography, and magnetic resonance images of the aorta were collected and analyzed. RESULTS: There were 189 patients whose mean age was 36 years, and 67% were men. Ten patients presented with acute type A dissection and 29 had mitral regurgitation. There were 52 patients at risk at 20 years. Mortality rate at 20 years was 21.5% (95% CI: 14.7%-30.8%); advancing age and preoperative aortic dissections were associated with increased risk of death by multivariable analysis. At 20 years, the cumulative incidence of moderate or severe aortic insufficiency was 14.5% (95% CI: 9.5%-22.0%), reoperation on the aortic valve was 7.5% (95% CI: 3.9%-14.7%), and new distal aortic dissections was 19.9% (95% CI: 13.9%-28.5%). Remodeling of aortic root was associated with greater risk of developing aortic insufficiency and aortic valve reoperation than reimplantation of the aortic valve. CONCLUSIONS: Aortic valve sparing operations provide stable aortic valve function and low rates of valve-related complications during the first 2 decades of follow-up but aortic dissections remain problematic in patients with MS.

Endosome Traffic Modulates Pro-Inflammatory Signal Transduction in CD4+ T Cells-Implications for the Pathogenesis of Systemic Lupus Erythematosus.

Endocytic recycling regulates the cell surface receptor composition of the plasma membrane. The surface expression levels of the T cell receptor (TCR), in concert with signal transducing co-receptors, regulate T cell responses, such as proliferation, differentiation, and cytokine production. Altered TCR expression contributes to pro-inflammatory skewing, which is a hallmark of autoimmune diseases, such as systemic lupus erythematosus (SLE), defined by a reduced function of regulatory T cells (Tregs) and the expansion of CD4+ helper T (Th) cells. The ensuing secretion of inflammatory cytokines, such as interferon-γ and interleukin (IL)-4, IL-17, IL-21, and IL-23, trigger autoantibody production and tissue infiltration by cells of the adaptive and innate immune system that induce organ damage. Endocytic recycling influences immunological synapse formation by CD4+ T lymphocytes, signal transduction from crosslinked surface receptors through recruitment of adaptor molecules, intracellular traffic of organelles, and the generation of metabolites to support growth, cytokine production, and epigenetic control of DNA replication and gene expression in the cell nucleus. This review will delineate checkpoints of endosome traffic that can be targeted for therapeutic interventions in autoimmune and other disease conditions.

Reimplantation of the aortic valve in patients with tricuspid aortic valve: the Toronto General Hospital experience.

Background: Aortic valve sparing operations were introduced three decades ago but controversy remains regarding its appropriateness, reproducibility and durability. This article describes the long-term outcomes of patients who had reimplantation of the aortic valve. Methods: All patients who had reimplantation of a tricuspid aortic valve at Toronto General Hospital from 1989 through 2019 were selected for this study. Patients were followed prospectively with periodical clinical assessments and imaging of the heart and aorta. Results: Four hundred and four patients were identified. The median age was 48.0 [interquartile range (IQR), 35.0-59.0] years and 310 (76.7%) were men. There were 150 patients with Marfan syndrome, 20 with Loeys-Dietz syndrome and 33 with acute or chronic aortic dissections. The median follow-up was 11.7 (IQR, 6.8-17.1) years. There were 55 patients alive and without reoperation at 20 years. The cumulative mortality at 20 years was 26.7% [95% confidence interval (CI): 20.6-34.2%], the cumulative incidence of reoperation on the aortic valve was 7.0% (95% CI: 4.0-12.2%) and the development of moderate or severe aortic insufficiency was 11.8% (95% CI: 8.5-16.5%). We could not identify variables associated with reoperation on the aortic valve or with the development of aortic insufficiency. New distal aortic dissections were common in patients with associated genetic syndromes. Conclusions: Reimplantation of the aortic valve in patients with tricuspid aortic valve provides excellent aortic valve function during the first two decades of follow-up. Distal aortic dissections are relatively common in patients with associated genetic syndromes.

Human cortical interneurons optimized for grafting specifically integrate, abort seizures, and display prolonged efficacy without over-inhibition.

Previously, we demonstrated the efficacy of human pluripotent stem cell (hPSC)-derived GABAergic cortical interneuron (cIN) grafts in ameliorating seizures. However, a safe and reliable clinical translation requires a mechanistic understanding of graft function, as well as the assurance of long-term efficacy and safety. By employing hPSC-derived chemically matured migratory cINs in two models of epilepsy, we demonstrate lasting efficacy in treating seizures and comorbid deficits, as well as safety without uncontrolled growth. Host inhibition does not increase with increasing grafted cIN densities, assuring their safety without the risk of over-inhibition. Furthermore, their closed-loop optogenetic activation aborted seizure activity, revealing mechanisms of graft-mediated seizure control and allowing graft modulation for optimal translation. Monosynaptic tracing shows their extensive and specific synaptic connections with host neurons, resembling developmental connection specificity. These results offer confidence in stem cell-based therapy for epilepsy as a safe and reliable treatment for patients suffering from intractable epilepsy.

Impact of schizophrenia GWAS loci converge onto distinct pathways in cortical interneurons vs glutamatergic neurons during development.

Remarkable advances have been made in schizophrenia (SCZ) GWAS, but gleaning biological insight from these loci is challenging. Genetic influences on gene expression (e.g., eQTLs) are cell type-specific, but most studies that attempt to clarify GWAS loci's influence on gene expression have employed tissues with mixed cell compositions that can obscure cell-specific effects. Furthermore, enriched SCZ heritability in the fetal brain underscores the need to study the impact of SCZ risk loci in specific developing neurons. MGE-derived cortical interneurons (cINs) are consistently affected in SCZ brains and show enriched SCZ heritability in human fetal brains. We identified SCZ GWAS risk genes that are dysregulated in iPSC-derived homogeneous populations of developing SCZ cINs. These SCZ GWAS loci differential expression (DE) genes converge on the PKC pathway. Their disruption results in PKC hyperactivity in developing cINs, leading to arborization deficits. We show that the fine-mapped GWAS locus in the ATP2A2 gene of the PKC pathway harbors enhancer marks by ATACseq and ChIPseq, and regulates ATP2A2 expression. We also generated developing glutamatergic neurons (GNs), another population with enriched SCZ heritability, and confirmed their functionality after transplantation into the mouse brain. Then, we identified SCZ GWAS risk genes that are dysregulated in developing SCZ GNs. GN-specific SCZ GWAS loci DE genes converge on the ion transporter pathway, distinct from those for cINs. Disruption of the pathway gene CACNA1D resulted in deficits of Ca2+ currents in developing GNs, suggesting compromised neuronal function by GWAS loci pathway deficits during development. This study allows us to identify cell type-specific and developmental stage-specific mechanisms of SCZ risk gene function, and may aid in identifying mechanism-based novel therapeutic targets.

Initial Psychometric Testing of a Brief Maternal Oral Symptom Survey.

INTRODUCTION: Oral health is an important component of maternal health. Pregnant women face unique oral health challenges. Although there is abundant evidence of the strong association between poor oral health and adverse pregnancy outcomes, oral health assessment is frequently overlooked by prenatal care providers. The purpose of this study was to test the reliability and validity of a brief maternal oral symptom survey for potential use by prenatal care providers to screen pregnant women for oral health concerns. METHODS: This study provides results of preliminary psychometric testing of a brief maternal oral symptom survey. The survey was administered to 455 pregnant African American women at 2 time points: early pregnancy (8-14 weeks) and late pregnancy (24-30 weeks). Saliva samples were collected on a small subset of the larger sample (n = 34). Cronbach's alpha was used to measure the internal consistency of the survey. Content validity was assessed using an expert panel (n = 32), and criterion validity was assessed by testing the association of survey items with salivary biomarkers. RESULTS: The oral health survey showed moderate overall content validity. Scores on the content validity index identified that 5 out of 10 survey items were relevant, clear, and important. Log-transformed C-reactive protein levels were associated with reported "dry mouth" and education. Cronbach's alpha value was 0.502. DISCUSSION: Suggested revisions of the oral symptom survey include removing items that performed poorly on the content validity index and additional inclusion of sociodemographic variables. With further testing and validation, this survey has the potential to be an effective screening tool to assess for prenatal oral health concerns that increase risk for poor birth outcomes.

Age-Related Changes in the Anatomy of the Triangle of Koch: Implications for Catheter Ablation of Atrioventricular Nodal Re-entry Tachycardia.

BACKGROUND: Atrioventricular nodal re-entrant tachycardia is the most common type of paroxysmal supraventricular tachycardia. We sought to assess whether important anatomic factors, such as the location of the slow pathway, proximity to the bundle of His, and coronary sinus ostium dimensions, varied with patient age, and whether these factors had an impact on procedural duration, acute success, and complications. METHODS: Baseline demographic and procedural data were collected, and the maps were analyzed. Linear regression models were performed to evaluate the associations between age and these anatomic variations. Associations were also assessed, with age categorized as being ≥ 60 years or < 60 years. RESULTS: The slow pathway was more commonly located in a superior location relative to the coronary sinus ostium in older patients. The location of the slow pathway moved in a superior direction by 1 mm for every increase in 2 years from the mean estimate of age. Additionally the slow pathway tended to be closer to the coronary sinus ostium in older patients, and the diameter of the ostium was larger in older patients. This resulted in longer procedure time, longer ablation times, and a greater need for long sheaths for stability. CONCLUSIONS: The location of the slow pathway becomes more superior and closer to the coronary sinus ostium with increasing age. Additionally, the coronary sinus diameter increases with age. These factors result in longer ablation and procedural times in older patients.

CONTEXTE: La tachycardie par réentrée nodale auriculoventriculaire est le type le plus fréquent de tachycardie supraventriculaire paroxystique. Nous avons voulu évaluer si des facteurs anatomiques importants, tels que l'emplacement de la voie lente, la proximité du faisceau de His et les dimensions de l'orifice du sinus coronaire (ostium), variaient avec l'âge, et si ces facteurs avaient un effet sur la durée de l'intervention, le succès à court terme et les complications. MÉTHODOLOGIE: Des données sur les caractéristiques démographiques initiales et l'intervention ont été recueillies, et les cartes obtenues ont été analysées. Des modèles de régression linéaire ont servi à déterminer les corrélations entre l'âge et ces variations anatomiques. Les corrélations ont aussi été évaluées selon des catégories d'âge, soit ≥ 60 ans et < 60 ans. RÉSULTATS: La voie lente a été repérée plus souvent dans un emplacement supérieur par rapport à l'orifice du sinus coronaire chez les patients plus âgés. L'emplacement de la voie lente s'était déplacé de 1 mm vers le haut pour chaque augmentation de 2 ans de l'estimation moyenne de l'âge. Par ailleurs, chez les patients plus âgés, la voie lente était généralement plus proche de l'orifice du sinus coronaire et le diamètre de l'orifice était élargi. Ces variations se sont traduites par une augmentation du temps d'intervention et d'ablation et par un besoin accru de longues gaines pour la stabilité. CONCLUSIONS: L'emplacement de la voie lente devient plus éloigné vers le haut et plus proche de l'orifice du sinus coronaire avec le vieillissement. De plus, le diamètre du sinus coronaire augmente avec l'âge. Ces facteurs entraînent des temps d'ablation et d'intervention plus longs chez les patients plus âgés.

Activated microglia cause metabolic disruptions in developmental cortical interneurons that persist in interneurons from individuals with schizophrenia.

The mechanisms by which prenatal immune activation increase the risk for neuropsychiatric disorders are unclear. Here, we generated developmental cortical interneurons (cINs)-which are known to be affected in schizophrenia (SCZ) when matured-from induced pluripotent stem cells (iPSCs) derived from healthy controls (HCs) and individuals with SCZ and co-cultured them with or without activated microglia. Co-culture with activated microglia disturbed metabolic pathways, as indicated by unbiased transcriptome analyses, and impaired mitochondrial function, arborization, synapse formation and synaptic GABA release. Deficits in mitochondrial function and arborization were reversed by alpha lipoic acid and acetyl-L-carnitine treatments, which boost mitochondrial function. Notably, activated-microglia-conditioned medium altered metabolism in cINs and iPSCs from HCs but not in iPSCs from individuals with SCZ or in glutamatergic neurons. After removal of activated-microglia-conditioned medium, SCZ cINs but not HC cINs showed prolonged metabolic deficits, which suggests that there is an interaction between SCZ genetic backgrounds and environmental risk factors.

iPSC-derived homogeneous populations of developing schizophrenia cortical interneurons have compromised mitochondrial function.

Schizophrenia (SCZ) is a neurodevelopmental disorder. Thus, studying pathogenetic mechanisms underlying SCZ requires studying the development of brain cells. Cortical interneurons (cINs) are consistently observed to be abnormal in SCZ postmortem brains. These abnormalities may explain altered gamma oscillation and cognitive function in patients with SCZ. Of note, currently used antipsychotic drugs ameliorate psychosis, but they are not very effective in reversing cognitive deficits. Characterizing mechanisms of SCZ pathogenesis, especially related to cognitive deficits, may lead to improved treatments. We generated homogeneous populations of developing cINs from 15 healthy control (HC) iPSC lines and 15 SCZ iPSC lines. SCZ cINs, but not SCZ glutamatergic neurons, show dysregulated Oxidative Phosphorylation (OxPhos) related gene expression, accompanied by compromised mitochondrial function. The OxPhos deficit in cINs could be reversed by Alpha Lipoic Acid/Acetyl-L-Carnitine (ALA/ALC) but not by other chemicals previously identified as increasing mitochondrial function. The restoration of mitochondrial function by ALA/ALC was accompanied by a reversal of arborization deficits in SCZ cINs. OxPhos abnormality, even in the absence of any circuit environment with other neuronal subtypes, appears to be an intrinsic deficit in SCZ cINs.

Correction: iPSC-derived homogeneous populations of developing schizophrenia cortical interneurons have compromised mitochondrial function.

A correction to this paper has been published and can be accessed via a link at the top of the paper.

Large-Scale Generation and Characterization of Homogeneous Populations of Migratory Cortical Interneurons from Human Pluripotent Stem Cells.

During development, cortical interneurons (cINs) are generated from the ventral telencephalon, robustly migrate to the dorsal telencephalon, make local synaptic connections, and critically regulate brain circuitry by inhibiting other neurons. Thus, their abnormality is associated with various brain disorders. Human pluripotent stem cell (hPSC)-derived cINs can provide unlimited sources with which to study the pathogenesis mechanism of these disorders as well as provide a platform to develop novel therapeutics. By employing spinner culture, we could obtain a >10-fold higher yield of cIN progenitors compared to conventional culture without affecting their phenotype. Generated cIN spheres can be maintained feeder-free up to 10 months and are optimized for passaging and cryopreservation. In addition, we identified a combination of chemicals that synchronously matures generated progenitors into SOX6+KI67- migratory cINs and extensively characterized their maturation in terms of metabolism, migration, arborization, and electrophysiology. When transplanted into mouse brains, chemically matured migratory cINs generated grafts that efficiently disperse and integrate into the host circuitry without uncontrolled growth, making them an optimal cell population for cell therapy. Efficient large-scale generation of homogeneous migratory cINs without the need of feeder cells will play a critical role in the full realization of hPSC-derived cINs for development of novel therapeutics.

Assessment of a mitral valve replacement skills trainer: a simplified, low-cost approach.

OBJECTIVES: Simulated mitral valve replacement may aid in the assessment of technical skills required for adequate performance in the operating room. We sought to design and assess a mitral valve replacement training station that is low-cost, nonperishable, portable, and reproducible as a first step in developing a mitral valve surgical skills curriculum. METHODS: Nineteen physicians (7 general surgery residents, 8 cardiothoracic surgery residents, and 4 attending cardiothoracic surgeons) underwent simulated mitral valve replacement testing. Simulated mitral valve replacement was performed on a training station consisting of a replaceable "mitral annulus" inside a restrictive "left atrium." Eight components of performance were graded on a 5-point scale. A composite score (100 point maximum) was calculated by weighting the grades by procedural time. The effect of training level was evaluated using analysis of variance and post hoc Tukey honestly significant difference. RESULTS: The speed of simulated mitral valve replacement varied among general surgery residents, cardiothoracic surgery residents, and attending cardiothoracic surgeons (52.9 ± 9.0 vs 32.8 ± 4.7 vs 28.0 ± 3.5 minutes, respectively; F = 25.3; P < .001). Level of training significantly affected all 8 evaluation components (P < .001). Composite scores increased with level of training (general surgery residents 32.9 ± 11.4, cardiothoracic surgery residents 65.1 ± 11.5, and attending cardiothoracic surgeons 88.3 ± 7.8 of a possible 100 points; F = 35.7; P < .001). Cardiothoracic surgery residents who reported having performed 10 to 50 mitral valve replacements as the primary surgeon had a composite score of 65.0 ± 2.8 (P < .01 compared with attending cardiothoracic surgeons). CONCLUSIONS: Simulated mitral valve replacement can be performed using this simple, affordable, portable setup. Performance scores correlate with level of training and experience, but residents who performed 10 to 50 mitral valve replacements still failed to reach attending-level proficiency. This training simulator may facilitate skills practice and evaluation of competency in cardiac surgery trainees.

Protein targets of inflammatory serine proteases and cardiovascular disease.

Serine proteases are a key component of the inflammatory response as they are discharged from activated leukocytes and mast cells or generated through the coagulation cascade. Their enzymatic activity plays a major role in the body's defense mechanisms but it has also an impact on vascular homeostasis and tissue remodeling. Here we focus on the biological role of serine proteases in the context of cardiovascular disease and their mechanism(s) of action in determining specific vascular and tissue phenotypes. Protease-activated receptors (PARs) mediate serine protease effects; however, these proteases also exert a number of biological activities independent of PARs as they target specific protein substrates implicated in vascular remodeling and the development of cardiovascular disease thus controlling their activities. In this review both PAR-dependent and -independent mechanisms of action of serine proteases are discussed for their relevance to vascular homeostasis and structural/functional alterations of the cardiovascular system. The elucidation of these mechanisms will lead to a better understanding of the molecular forces that control vascular and tissue homeostasis and to effective preventative and therapeutic approaches.