Adiposity, immunity, and inflammation: interrelationships in health and disease: A report from 24th annual Harvard nutrition obesity symposium, June 2023.

The rapidly evolving field of immunometabolism explores how changes in local immune environments may affect the key metabolic and cellular processes, including that of adipose tissue. Importantly, these changes may contribute to low-grade systemic inflammation. In turn, chronic low-grade inflammation affecting adipose tissue may exacerbate the outcome of metabolic diseases. Novel advances in our understanding of immune-metabolic processes may critically lead to interventions to reduce disease severity and progression. An important example in this regard relates to obesity, which has a multifaceted effect on immunity activating the pro-inflammatory pathways such as inflammasome and disrupting cellular homeostasis. This multifaceted effect of obesity can be investigated through study of downstream conditions using cellular and systemic investigative techniques. To further explore this field, the NIH P30 Nutrition Obesity Research Center at Harvard in partnership with the Harvard Medical School assembled experts to present at its 24th annual Symposium entitled "Adiposity, Immunity, and Inflammation: Interrelationships in Health and Disease on June 07, 2023. This manuscript seeks to synthesize and present key findings from the symposium highlighting new research and novel disease-specific advances in the field. Better understanding the interaction between metabolism and immunity offers promising preventative and treatment therapies for obesity-related immunometabolic diseases.

Adducin Regulates Sarcomere Disassembly During Cardiomyocyte Mitosis.

BACKGROUND: Recent interest in understanding cardiomyocyte cell cycle has been driven by potential therapeutic applications in cardiomyopathy. However, despite recent advances, cardiomyocyte mitosis remains a poorly understood process. For example, it is unclear how sarcomeres are disassembled during mitosis to allow the abscission of daughter cardiomyocytes. METHODS: Here, we use a proteomics screen to identify adducin, an actin capping protein previously not studied in cardiomyocytes, as a regulator of sarcomere disassembly. We generated many adeno-associated viruses and cardiomyocyte-specific genetic gain-of-function models to examine the role of adducin in neonatal and adult cardiomyocytes in vitro and in vivo. RESULTS: We identify adducin as a regulator of sarcomere disassembly during mammalian cardiomyocyte mitosis. α/γ-adducins are selectively expressed in neonatal mitotic cardiomyocytes, and their levels decline precipitously thereafter. Cardiomyocyte-specific overexpression of various splice isoforms and phospho-isoforms of α-adducin in identified Thr445/Thr480 phosphorylation of a short isoform of α-adducin as a potent inducer of neonatal cardiomyocyte sarcomere disassembly. Concomitant overexpression of this α-adducin variant along with γ-adducin resulted in stabilization of the adducin complex and persistent sarcomere disassembly in adult mice, which is mediated by interaction with α-actinin. CONCLUSIONS: These results highlight an important mechanism for coordinating cytoskeletal morphological changes during cardiomyocyte mitosis.

Correlates of Plasma NT-proBNP/Cyclic GMP Ratio in Heart Failure With Preserved Ejection Fraction: An Analysis of the RELAX Trial.

BACKGROUND: Phosphodiesterases degrade cyclic GMP (cGMP), the second messenger that mediates the cardioprotective effects of natriuretic peptides. High natriuretic peptide/cGMP ratio may reflect, in part, phosphodiesterase activity. Correlates of natriuretic peptide/cGMP in patients with heart failure with preserved ejection fraction are not well understood. Among patients with heart failure with preserved ejection fraction in the RELAX (Phosphodiesterase-5 Inhibition to Improve Clinical Status and Exercise Capacity in Heart Failure With Preserved Ejection Fraction) trial, we examined (1) cross-sectional correlates of circulating NT-proBNP (N-terminal pro-B-type natriuretic peptide)/cGMP ratio, (2) whether selective phosphodiesterase-5 inhibition by sildenafil changed the ratio, and (3) whether the effect of sildenafil on 24-week outcomes varied by baseline ratio. METHODS AND RESULTS: In 212 subjects, NT-proBNP/cGMP ratio was calculated at randomization and 24 weeks. Correlates of the ratio and its change were examined in multivariable proportional odds models. Whether baseline ratio modified the sildenafil effect on outcomes was examined by interaction terms. Higher NT-proBNP/cGMP ratio was associated with greater left ventricular mass and troponin, the presence of atrial fibrillation, and lower estimated glomerular filtration rate and peak oxygen consumption. Compared with placebo, sildenafil did not alter the ratio from baseline to 24 weeks (P=0.17). The effect of sildenafil on 24-week change in peak oxygen consumption, left ventricular mass, or clinical composite outcome was not modified by baseline NT-proBNP/cGMP ratio (P-interaction >0.30 for all). CONCLUSIONS: Among patients with heart failure with preserved ejection fraction, higher NT-proBNP/cGMP ratio associated with an adverse cardiorenal phenotype, which was not improved by selective phosphodiesterase-5 inhibition. Other phosphodiesterases may be greater contributors than phosphodiesterase-5 to the adverse phenotype associated with a high natriuretic peptide/cGMP ratio in HFpEF. REGISTRATION INFORMATION: clinicaltrials.gov. Identifier: NCT00763867.

Increased mortality in infants with abnormal T-cell receptor excision circles.

BACKGROUND: T-Cell Receptor Excision Circles based newborn screening (TREC-NBS) allows for early detection of T-cell lymphopenia in infants with primary immunodeficiency disorders (PIDD). The utility of abnormal TREC-NBS in infants without PIDD is not well studied. We sought to evaluate the association of abnormal TREC-NBS with mortality. METHODS: 365,207 TREC-NBS from October 2011 to December 2014 were reviewed. 467 newborns had abnormal screens and did not meet the criteria for a PIDD diagnosis. Cases were matched to controls (1:3) based on gestational age, birth weight, neonatal intensive care unit status (NICU), and race. Data were obtained through NBS, birth and death certificates records from the Michigan Department of Health and Human Services (MDHHS) databases. RESULTS: Infants with abnormal TREC-NBS had higher mortality even when PIDD was ruled-out. Transient abnormal TREC-NBS was not associated with higher mortality, but unresolved or late abnormal TREC-NBS was associated with higher mortality. Infants with late abnormal TREC-NBS had severe prematurity, lower birth weight, lower Apgar scores, and higher percentage of congenital anomalies. CONCLUSION: Infants with abnormal TREC-NBS may be at a higher risk of morbidity and mortality and should be carefully followed, especially if discharged home before a repeat screen can be completed. IMPACT: This study explores the risk factors and mortality for newborns with secondary T-cell lymphopenia captured on T-Cell Receptor Excision Circles based newborn screening (TREC-NBS). Abnormal TREC-NBS allows for prompt life-saving interventions for primary immunological conditions such as Severe Combined Immunodeficiency (SCID), but can also be associated with non-immunologic conditions. Unresolved and late abnormal TREC-NBS is associated with higher mortality even without primary immunodeficiency, likely detected in infants with more severe prematurity, lower birth weight, and congenital anomalies. TREC-NBS positive infants with secondary T-cell lymphopenia require special attention and close monitoring.

Defying Gravity: WEEP promotes negative gravitropism in peach trees by establishing asymmetric auxin gradients.

Trees with weeping shoot architectures are valued for their beauty and are a resource for understanding how plants regulate posture control. The peach (Prunus persica) weeping phenotype, which has elliptical downward arching branches, is caused by a homozygous mutation in the WEEP gene. Little is known about the function of WEEP despite its high conservation throughout Plantae. Here, we present the results of anatomical, biochemical, biomechanical, physiological, and molecular experiments that provide insight into WEEP function. Our data suggest that weeping peach trees do not have defects in branch structure. Rather, transcriptomes from the adaxial (upper) and abaxial (lower) sides of standard and weeping branch shoot tips revealed flipped expression patterns for genes associated with early auxin response, tissue patterning, cell elongation, and tension wood development. This suggests that WEEP promotes polar auxin transport toward the lower side during shoot gravitropic response, leading to cell elongation and tension wood development. In addition, weeping peach trees exhibited steeper root systems and faster lateral root gravitropic response. This suggests that WEEP moderates root gravitropism and is essential to establishing the set-point angle of lateral roots from the gravity vector. Additionally, size-exclusion chromatography indicated that WEEP proteins self-oligomerize, like other proteins with sterile alpha motif (SAM) domains. Collectively, our results from weeping peach provide insight into polar auxin transport mechanisms associated with gravitropism and lateral shoot and root orientation.

The MYPT2-regulated striated muscle-specific myosin light chain phosphatase limits cardiac myosin phosphorylation in vivo.

The physiological importance of cardiac myosin regulatory light chain (RLC) phosphorylation by its dedicated cardiac myosin light chain kinase has been established in both humans and mice. Constitutive RLC-phosphorylation, regulated by the balanced activities of cardiac myosin light chain kinase and myosin light chain phosphatase (MLCP), is fundamental to the biochemical and physiological properties of myofilaments. However, limited information is available on cardiac MLCP. In this study, we hypothesized that the striated muscle-specific MLCP regulatory subunit, MYPT2, targets the phosphatase catalytic subunit to cardiac myosin, contributing to the maintenance of cardiac function in vivo through the regulation of RLC-phosphorylation. To test this hypothesis, we generated a floxed-PPP1R12B mouse model crossed with a cardiac-specific Mer-Cre-Mer to conditionally ablate MYPT2 in adult cardiomyocytes. Immunofluorescence microscopy using the gene-ablated tissue as a control confirmed the localization of MYPT2 to regions where it overlaps with a subset of RLC. Biochemical analysis revealed an increase in RLC-phosphorylation in vivo. The loss of MYPT2 demonstrated significant protection against pressure overload-induced hypertrophy, as evidenced by heart weight, qPCR of hypertrophy-associated genes, measurements of myocyte diameters, and expression of ß-MHC protein. Furthermore, mantATP chase assays revealed an increased ratio of myosin heads distributed to the interfilament space in MYPT2-ablated heart muscle fibers, confirming that RLC-phosphorylation regulated by MLCP, enhances cardiac performance in vivo. Our findings establish MYPT2 as the regulatory subunit of cardiac MLCP, distinct from the ubiquitously expressed canonical smooth muscle MLCP. Targeting MYPT2 to increase cardiac RLC-phosphorylation in vivo may improve baseline cardiac performance, thereby attenuating pathological hypertrophy.

Clinical outcomes associated with anti-Xa-monitored enoxaparin for venous thromboembolism prophylaxis.

STUDY OBJECTIVE: The objective of the study was to assess clinical outcomes (composite of any venous thromboembolism [VTE], any bleeding, and mortality) associated with anti-Xa monitoring in the 30 days following enoxaparin initiation for VTE prophylaxis. DESIGN: Retrospective cohort study. SETTING: Hospital within an academic healthcare system. PATIENTS: Propensity score-matched hospitalized adults receiving enoxaparin for VTE prophylaxis. INTERVENTION: Low-molecular-weight heparin anti-Xa monitoring. MEASUREMENTS AND MAIN RESULTS: During the 13-month study period, a total of 6611 patients received enoxaparin for VTE prophylaxis, 301 in the anti-Xa monitored group and 6310 in the unmonitored group (4.6% received monitoring). The mean age was 52.9 years and 52% of patients were male. The mean body mass index was 31 kg/m2 and the mean creatinine clearance was 109 mL/min. Twenty percent of patients had active cancer. The most common indication for enoxaparin prophylaxis was hospitalization for medical illness (52%) followed by nonorthopedic surgery (37%). The adjusted odds ratio for the primary outcome comparing monitored to unmonitored patients was 1.26 (95% confidence interval, 0.75-2.11). None of the between-group differences in the individual components of the composite outcome were statistically significant. CONCLUSIONS: Thirty-day clinical outcomes in patients receiving enoxaparin for VTE prophylaxis were not improved by anti-Xa monitoring. Our results support current evidence-based guideline recommendations against anti-Xa monitoring for patients receiving enoxaparin for VTE prophylaxis.

Single-cell transcriptional landscape of long non-coding RNAs orchestrating mouse heart development.

Long non-coding RNAs (lncRNAs) comprise the most representative transcriptional units of the mammalian genome. They are associated with organ development linked with the emergence of cardiovascular diseases. We used bioinformatic approaches, machine learning algorithms, systems biology analyses, and statistical techniques to define co-expression modules linked to heart development and cardiovascular diseases. We also uncovered differentially expressed transcripts in subpopulations of cardiomyocytes. Finally, from this work, we were able to identify eight cardiac cell-types; several new coding, lncRNA, and pcRNA markers; two cardiomyocyte subpopulations at four different time points (ventricle E9.5, left ventricle E11.5, right ventricle E14.5 and left atrium P0) that harbored co-expressed gene modules enriched in mitochondrial, heart development and cardiovascular diseases. Our results evidence the role of particular lncRNAs in heart development and highlight the usage of co-expression modular approaches in the cell-type functional definition.

Impaired T cell IRE1α/XBP1 signaling directs inflammation in experimental heart failure with preserved ejection fraction.

Heart failure with preserved ejection fraction (HFpEF) is a widespread syndrome with limited therapeutic options and poorly understood immune pathophysiology. Using a 2-hit preclinical model of cardiometabolic HFpEF that induces obesity and hypertension, we found that cardiac T cell infiltration and lymphoid expansion occurred concomitantly with cardiac pathology and that diastolic dysfunction, cardiomyocyte hypertrophy, and cardiac phospholamban phosphorylation were T cell dependent. Heart-infiltrating T cells were not restricted to cardiac antigens and were uniquely characterized by impaired activation of the inositol-requiring enzyme 1α/X-box-binding protein 1 (IRE1α/XBP1) arm of the unfolded protein response. Notably, selective ablation of XBP1 in T cells enhanced their persistence in the heart and lymphoid organs of mice with preclinical HFpEF. Furthermore, T cell IRE1α/XBP1 activation was restored after withdrawal of the 2 comorbidities inducing HFpEF, resulting in partial improvement of cardiac pathology. Our results demonstrated that diastolic dysfunction and cardiomyocyte hypertrophy in preclinical HFpEF were T cell dependent and that reversible dysregulation of the T cell IRE1α/XBP1 axis was a T cell signature of HFpEF.

Defying Gravity: WEEP promotes negative gravitropism in Prunus persica (peach) shoots and roots by establishing asymmetric auxin gradients.

Trees with weeping shoot architectures are valued for their beauty and serve as tremendous resources for understanding how plants regulate posture control. The Prunus persica (peach) weeping phenotype, which has elliptical downward arching branches, is caused by a homozygous mutation in the WEEP gene. Until now, little was known about the function of WEEP protein despite its high conservation throughout Plantae. Here, we present the results of anatomical, biochemical, biomechanical, physiological, and molecular experiments that provide insight into WEEP function. Our data suggest that weeping peach does not have defects in branch structure. Rather, transcriptomes from the adaxial (upper) and abaxial (lower) sides of standard and weeping branch shoot tips revealed flipped expression patterns for genes associated with early auxin response, tissue patterning, cell elongation, and tension wood development. This suggests that WEEP promotes polar auxin transport toward the lower side during shoot gravitropic response, leading to cell elongation and tension wood development. In addition, weeping peach trees exhibited steeper root systems and faster root gravitropic response, just as barley and wheat with mutations in their WEEP homolog EGT2. This suggests that the role of WEEP in regulating lateral organ angles and orientations during gravitropism may be conserved. Additionally, size-exclusion chromatography indicated that WEEP proteins self-oligomerize, like other SAM-domain proteins. This oligomerization may be required for WEEP to function in formation of protein complexes during auxin transport. Collectively, our results from weeping peach provide new insight into polar auxin transport mechanisms associated with gravitropism and lateral shoot and root orientation.

Impact of Short-Term (+)-JQ1 Exposure on Mouse Aorta: Unanticipated Inhibition of Smooth Muscle Contractility.

(+)-JQ1, a specific chemical inhibitor of bromodomain and extraterminal (BET) family protein 4 (BRD4), has been reported to inhibit smooth muscle cell (SMC) proliferation and mouse neointima formation via BRD4 regulation and modulate endothelial nitric oxide synthase (eNOS) activity. This study aimed to investigate the effects of (+)-JQ1 on smooth muscle contractility and the underlying mechanisms. Using wire myography, we discovered that (+)-JQ1 inhibited contractile responses in mouse aortas with or without functional endothelium, reducing myosin light chain 20 (LC20) phosphorylation and relying on extracellular Ca2+. In mouse aortas lacking functional endothelium, BRD4 knockout did not alter the inhibition of contractile responses by (+)-JQ1. In primary cultured SMCs, (+)-JQ1 inhibited Ca2+ influx. In aortas with intact endothelium, (+)-JQ1 inhibition of contractile responses was reversed by NOS inhibition (L-NAME) or guanylyl cyclase inhibition (ODQ) and by blocking the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) pathway. In cultured human umbilical vein endothelial cells (HUVECs), (+)-JQ1 rapidly activated AKT and eNOS, which was reversed by PI3K or ATK inhibition. Intraperitoneal injection of (+)-JQ1 reduced mouse systolic blood pressure, an effect blocked by co-treatment with L-NAME. Interestingly, (+)-JQ1 inhibition of aortic contractility and its activation of eNOS and AKT were mimicked by the (-)-JQ1 enantiomer, which is structurally incapable of inhibiting BET bromodomains. In summary, our data suggest that (+)-JQ1 directly inhibits smooth muscle contractility and indirectly activates the PI3K/AKT/eNOS cascade in endothelial cells; however, these effects appear unrelated to BET inhibition. We conclude that (+)-JQ1 exhibits an off-target effect on vascular contractility.

Methods for studying primary cilia in heart tissue after ischemia-reperfusion injury.

Cardiovascular diseases are the leading cause of death and disability worldwide. After heart injury triggered by myocardial ischemia or myocardial infarction, extensive zones of tissue are damaged and some of the tissue dies by necrosis and/or apoptosis. The loss of contractile mass activates a series of biochemical mechanisms that allow, through cardiac remodeling, the replacement of the dysfunctional heart tissue by fibrotic material. Our previous studies have shown that primary cilia, non-motile antenna-like structures at the cell surface required for the activation of specific signaling pathways, are present in cardiac fibroblasts and required for cardiac fibrosis induced by ischemia/reperfusion (I/R) in mice. I/R-induced myocardial fibrosis promotes the enrichment of ciliated cardiac fibroblasts where the myocardial injury occurs. Given discussions about the existence of cilia in specific cardiac cell types, as well as the functional relevance of studying cilia-dependent signaling in cardiac fibrosis after I/R, here we describe our methods to evaluate the presence and roles of primary cilia in cardiac fibrosis after I/R in mice.

Rapid, accurate publication and dissemination of clinical trial results: benefits and challenges.

Large-scale clinical trials are essential in cardiology and require rapid, accurate publication, and dissemination. Whereas conference presentations, press releases, and social media disseminate information quickly and often receive considerable coverage by mainstream and healthcare media, they lack detail, may emphasize selected data, and can be open to misinterpretation. Preprint servers speed access to research manuscripts while awaiting acceptance for publication by a journal, but these articles are not formally peer-reviewed and sometimes overstate the findings. Publication of trial results in a major journal is very demanding but the use of existing checklists can help accelerate the process. In case of rejection, procedures such as easing formatting requirements and possibly carrying over peer-review to other journals could speed resubmission. Secondary publications can help maximize benefits from clinical trials; publications of secondary endpoints and subgroup analyses further define treatment effects and the patient populations most likely to benefit. These rely on data access, and although data sharing is becoming more common, many challenges remain. Beyond publication in medical journals, there is a need for wider knowledge dissemination to maximize impact on clinical practice. This might be facilitated through plain language summary publications. Social media, websites, mainstream news outlets, and other publications, although not peer-reviewed, are important sources of medical information for both the public and for clinicians. This underscores the importance of ensuring that the information is understandable, accessible, balanced, and trustworthy. This report is based on discussions held on December 2021, at the 18th Global Cardiovascular Clinical Trialists meeting, involving a panel of editors of some of the top medical journals, as well as members of the lay press, industry, and clinical trialists.

Therapeutic Effect of Argatroban During Cardiopulmonary Resuscitation and Streptokinase During Extracorporeal Cardiopulmonary Resuscitation in a Porcine Model of Prolonged Cardiac Arrest.

Prolonged cardiac arrest (CA) causes microvascular thrombosis which is a potential barrier to organ reperfusion during extracorporeal cardiopulmonary resuscitation (ECPR). The aim of this study was to test the hypothesis that early intra-arrest anticoagulation during cardiopulmonary resuscitation (CPR) and thrombolytic therapy during ECPR improve recovery of brain and heart function in a porcine model of prolonged out-of-hospital CA. DESIGN: Randomized interventional trial. SETTING: University laboratory. SUBJECTS: Swine. INTERVENTIONS: In a blinded study, 48 swine were subjected to 8 minutes of ventricular fibrillation CA followed by 30 minutes of goal-directed CPR and 8 hours of ECPR. Animals were randomized into four groups (n = 12) and given either placebo (P) or argatroban (ARG; 350 mg/kg) at minute 12 of CA and either placebo (P) or streptokinase (STK, 1.5 MU) at the onset of ECPR. MEASUREMENTS AND MAIN RESULTS: Primary outcomes included recovery of cardiac function measured by cardiac resuscitability score (CRS: range 0-6) and recovery of brain function measured by the recovery of somatosensory-evoked potential (SSEP) cortical response amplitude. There were no significant differences in recovery of cardiac function as measured by CRS between groups (p = 0.16): P + P 2.3 (1.0); ARG + P = 3.4 (2.1); P + STK = 1.6 (2.0); ARG + STK = 2.9 (2.1). There were no significant differences in the maximum recovery of SSEP cortical response relative to baseline between groups (p = 0.73): P + P = 23% (13%); ARG + P = 20% (13%); P + STK = 25% (14%); ARG + STK = 26% (13%). Histologic analysis demonstrated reduced myocardial necrosis and neurodegeneration in the ARG + STK group relative to the P + P group. CONCLUSIONS: In this swine model of prolonged CA treated with ECPR, early intra-arrest anticoagulation during goal-directed CPR and thrombolytic therapy during ECPR did not improve initial recovery of heart and brain function but did reduce histologic evidence of ischemic injury. The impact of this therapeutic strategy on the long-term recovery of cardiovascular and neurological function requires further investigation.

Inflammatory Mechanisms in Heart Failure with Preserved Ejection Fraction.

Heart failure with preserved ejection fraction (HFpEF) is now the most common form of heart failure and a significant public health concern for which limited effective therapies exist. Inflammation triggered by comorbidity burden is a critical element of HFpEF pathophysiology. Here, we discuss evidence for comorbidity-driven systemic and myocardial inflammation and the mechanistic role of inflammation in pathological myocardial remodeling in HFpEF.

Medications Associated with Occurrence of Urinary Tract Infections in Patients with Diabetes, Heart Failure or Both.

BACKGROUND: Evidence broadly identifying medications newly-initiated prior to the occurrence of a urinary tract infection (UTI) in patients with diabetes, heart failure, or both of these conditions is lacking. OBJECTIVE: The aim was to broadly assess medication filling patterns and incidence of UTIs to identify medications or medication classes most frequently initiated prior to UTI occurrence. METHODS: This retrospective study utilizing a national claims database examined medications commonly initiated in the six months preceding a UTI in patients with diabetes and/or heart failure. Patients with a new diagnosis of UTI, a diagnosis of diabetes and/or heart failure, continuous enrollment in the database for at least 12 months prior to the index UTI occurrence, and who initiated at least one new medication in the 6 months preceding the index UTI were evaluated. RESULTS: 12,744 patients met criteria: 10,626 (83.4%) had a diagnosis of diabetes, 838 (6.6%) had a diagnosis of heart failure, and 1,280 (10.0%) had diagnoses for both. Opioids were the most commonly filled medication class among all three groups. Medications from the SGLT2i class were the twelfth, eleventh, and eighteenth most common medications filled prior to the index UTI for all patients, patients with diabetes, and patients with diabetes and heart failure, respectively. CONCLUSION: Opioids were by far the most commonly initiated medication class in the 6 months prior to UTI incidence in patients with diabetes and/or heart failure. SGLT2i medications were not commonly initiated in the 6 months prior to the occurrence of a UTI.