Glucagon Receptor Antagonist for Heart Failure With Preserved Ejection Fraction.

BACKGROUND: Heart failure with preserved ejection fraction (HFpEF) is an emerging major unmet need and one of the most significant clinic challenges in cardiology. The pathogenesis of HFpEF is associated with multiple risk factors. Hypertension and metabolic disorders associated with obesity are the 2 most prominent comorbidities observed in patients with HFpEF. Although hypertension-induced mechanical overload has long been recognized as a potent contributor to heart failure with reduced ejection fraction, the synergistic interaction between mechanical overload and metabolic disorders in the pathogenesis of HFpEF remains poorly characterized. METHOD: We investigated the functional outcome and the underlying mechanisms from concurrent mechanic and metabolic stresses in the heart by applying transverse aortic constriction in lean C57Bl/6J or obese/diabetic B6.Cg-Lepob/J (ob/ob) mice, followed by single-nuclei RNA-seq and targeted manipulation of a top-ranked signaling pathway differentially affected in the 2 experimental cohorts. RESULTS: In contrast to the post-transverse aortic constriction C57Bl/6J lean mice, which developed pathological features of heart failure with reduced ejection fraction over time, the post-transverse aortic constriction ob/ob mice showed no significant changes in ejection fraction but developed characteristic pathological features of HFpEF, including diastolic dysfunction, worsened cardiac hypertrophy, and pathological remodeling, along with further deterioration of exercise intolerance. Single-nuclei RNA-seq analysis revealed significant transcriptome reprogramming in the cardiomyocytes stressed by both pressure overload and obesity/diabetes, markedly distinct from the cardiomyocytes singularly stressed by pressure overload or obesity/diabetes. Furthermore, glucagon signaling was identified as the top-ranked signaling pathway affected in the cardiomyocytes associated with HFpEF. Treatment with a glucagon receptor antagonist significantly ameliorated the progression of HFpEF-related pathological features in 2 independent preclinical models. Importantly, cardiomyocyte-specific genetic deletion of the glucagon receptor also significantly improved cardiac function in response to pressure overload and metabolic stress. CONCLUSIONS: These findings identify glucagon receptor signaling in cardiomyocytes as a critical determinant of HFpEF progression and provide proof-of-concept support for glucagon receptor antagonism as a potential therapy for the disease.

Radiofrequency ablation of the occipital nerves for treatment of neuralgias and headache.

OBJECTIVE: The purpose of this study was to retrospectively assess the efficacy of radiofrequency ablation (RFA) therapy as a treatment for occipital neuralgias and headaches at health clinics in the United States between January 1, 2015 and June 20, 2022. We hypothesize that RFA is a minimally invasive treatment that provides significant pain relief long-term for occipital neuralgias and associated headaches. METHODS: This retrospective analysis studies data collected from 277 occipital nerve RFA patients who had adequate pre-procedure and post-procedure follow-up for data analysis. Data collected includes the patient's age, biological sex, BMI, headache diagnosis, pre-procedure, and post-procedure pain score using the visual analog scale (VAS), subjective percent improvement in symptom(s), and duration of symptom relief. Statistical analysis used SPSS software, version 26 (IBM), using a paired t-test to assess the significance between pre and post-occipital RFA therapy pain scores. p-values were significant if found to be ≤0.05. RESULTS: The mean pre-procedure pain score before RFA therapy for patients who completed at least 6 months of follow-up was 5.57 (SD = 1.87) and the mean post-procedure pain score after RFA therapy was 2.39 (SD = 2.42). The improvement in pain scores between pre-procedure and post-procedure was statistically significant with a p-value < 0.001. The mean patient-reported percent improvement in pain following RFA therapy was 63.53% (SD = 36.37). The mean duration of pain improvement was 253.9 days after the initiation of therapy (SD = 300.5). When excluding patients who did not have any relief following their RFA procedure, the average pre-procedure pain score was 5.54 (SD = 1.81) and post-procedure pain score was 1.71 (SD = 1.81) with a p-value < 0.001. CONCLUSION: This study demonstrates the minimally invasive, safe, and effective treatment of RFA in patients with refractory occipital neuralgias and headaches. Additional studies are necessary to illuminate ideal patient characteristics for RFA treatment and the potential for procedural complications and long-term side effects associated with occipital nerve RFA therapy.

Cell-autonomous effect of cardiomyocyte branched-chain amino acid catabolism in heart failure in mice.

Parallel to major changes in fatty acid and glucose metabolism, defect in branched-chain amino acid (BCAA) catabolism has also been recognized as a metabolic hallmark and potential therapeutic target for heart failure. However, BCAA catabolic enzymes are ubiquitously expressed in all cell types and a systemic BCAA catabolic defect is also manifested in metabolic disorder associated with obesity and diabetes. Therefore, it remains to be determined the cell-autonomous impact of BCAA catabolic defect in cardiomyocytes in intact hearts independent from its potential global effects. In this study, we developed two mouse models. One is cardiomyocyte and temporal-specific inactivation of the E1α subunit (BCKDHA-cKO) of the branched-chain α-ketoacid dehydrogenase (BCKDH) complex, which blocks BCAA catabolism. Another model is cardiomyocyte specific inactivation of the BCKDH kinase (BCKDK-cKO), which promotes BCAA catabolism by constitutively activating BCKDH activity in adult cardiomyocytes. Functional and molecular characterizations showed E1α inactivation in cardiomyocytes was sufficient to induce loss of cardiac function, systolic chamber dilation and pathological transcriptome reprogramming. On the other hand, inactivation of BCKDK in intact heart does not have an impact on baseline cardiac function or cardiac dysfunction under pressure overload. Our results for the first time established the cardiomyocyte cell autonomous role of BCAA catabolism in cardiac physiology. These mouse lines will serve as valuable model systems to investigate the underlying mechanisms of BCAA catabolic defect induced heart failure and to provide potential insights for BCAA targeted therapy.

Lipid-independent activation of a muscle-specific PKCα splicing variant.

Protein kinase C-α (PKCα) plays a major role in a diverse range of cellular processes. Studies to date have defined the regulatory controls and function of PKCα entirely based upon the previously annotated ubiquitously expressed prototypical isoform. From RNA-seq-based transcriptome analysis in murine heart, we identified a previously unannotated PKCα variant produced by alternative RNA splicing. This PKCα transcript variant, which we named PKCα-novel exon (PKCα-NE), contains an extra exon between exon 16 and exon 17, and is specifically detected in adult mouse cardiac and skeletal muscle, but not other tissues; it is also detected in human hearts. This transcript variant yields a PKCα isoform with additional 16 amino acids inserted in its COOH-terminal variable region. Although the canonical PKCα enzyme is a lipid-dependent kinase, in vitro kinase assays show that PKCα-NE displays a high level of basal lipid-independent catalytic activity. Our unbiased proteomic analysis identified a specific interaction between PKCα-NE and eukaryotic elongation factor-1α (eEF1A1). Studies in cardiomyocytes link PKCα-NE expression to an increase in eEF1A1 phosphorylation and elevated protein synthesis. In summary, we have identified a previously uncharacterized muscle-specific PKCα splicing variant, PKCα-NE, with distinct biochemical properties that plays a unique role in the control of the protein synthesis machinery in cardiomyocytes.NEW & NOTEWORTHY PKCα is an important signaling molecule extensively studied in many cellular processes. However, no isoforms have been reported for PKCα except one prototypic isoform. Alternative mRNA splicing of Prkca gene was detected for the first time in rodent and human cardiac tissue, which can produce a previously unknown PKCα-novel exon (NE) isoform. The biochemistry and molecular effects of PKCα-NE are markedly different from PKCα wild type, suggesting potential functional diversity of PKCα signaling in muscle.

Temporary Peripheral Nerve Stimulation as Treatment for Chronic Pain.

INTRODUCTION: Chronic pain is a growing problem across the world, and in the midst of an opioid epidemic, it is imperative that alternative treatment measures are identified to help alleviate the pain experienced by these patients. Chronic pain greatly affects ones quality of life and many patients do not experience adequate relief with conventional treatment measures. The purpose of this retrospective analysis is to assess the efficacy of peripheral nerve stimulation (PNS) therapy in adult patients suffering from chronic pain refractory to conventional treatment measures who underwent therapy on various anatomical locations. METHODS: This retrospective analysis consisted of data collected from electronic health records for n = 89 patients who underwent PNS therapy. Data collected relates to patient age, sex, weight, height, body mass index (BMI), diagnosis, targeted nerves, follow-up encounters, pain scores from before and after PNS therapy, and duration of improvement. Statistical analysis used SPSS software, version 26 (IBM), using a paired t test to assess significance between pre and post PNS therapy pain scores. P values were significant if found to be ≤ 0.05. Further analysis assessed the correlation between age and BMI with visual analog scale (VAS) pain improvement and subjective percentage pain relief. RESULTS: The mean pre-operative (pre-op) pain score before PNS therapy was 6.36 (standard deviation (SD) = 2.18, SEM = 0.23) and the mean post-operative (post-op) pain score after PNS therapy was 4.19 (SD = 2.70, SEM = 0.29). The mean patient-reported percent improvement in pain following PNS therapy was 49.04% (SD = 34.79). The improvement in pain scores between pre-op and post-op was statistically significant (M = 2.17, SD = 2.82, SEM = 0.30, t(88) = 7.26, p < .001), 95% confidence interval (CI) [1.57, 2.76]. The mean duration of improvement for patients was 123 days after therapy initiation (min = 6, max = 683, SD = 126). CONCLUSIONS: This study demonstrated the potential role for PNS therapy in improving patient-reported pain levels for various neuropathies, targeting various nerves. With PNS therapy's use as a chronic pain treatment and available research being limited, further study needs to be done on the efficacy of PNS therapy for pain management and complications associated with PNS device placements at various locations.

Metal dependent protein phosphatase PPM family in cardiac health and diseases.

Protein phosphorylation and dephosphorylation is central to signal transduction in nearly every aspect of cellular function, including cardiovascular regulation and diseases. While protein kinases are often regarded as the molecular drivers in cellular signaling with high specificity and tight regulation, dephosphorylation mediated by protein phosphatases is also gaining increasing appreciation as an important part of the signal transduction network essential for the robustness, specificity and homeostasis of cell signaling. Metal dependent protein phosphatases (PPM, also known as protein phosphatases type 2C, PP2C) belong to a highly conserved family of protein phosphatases with unique biochemical and molecular features. Accumulating evidence also indicates important and specific functions of individual PPM isoform in signaling and cellular processes, including proliferation, senescence, apoptosis and metabolism. At the physiological level, abnormal PPM expression and activity have been implicated in major human diseases, including cancer, neurological and cardiovascular disorders. Finally, inhibitors for some of the PPM members have been developed as a potential therapeutic strategy for human diseases. In this review, we will focus on the background information about the biochemical and molecular features of major PPM family members, with emphasis on their demonstrated or potential roles in cardiac pathophysiology. The current challenge and potential directions for future investigations will also be highlighted.

Involvement of Low-Density Lipoprotein Receptor in the Pathogenesis of Pulmonary Hypertension.

Background Recently, we and others have reported a causal role for oxidized lipids in the pathogenesis of pulmonary hypertension (PH). However, the role of low-density lipoprotein receptor (LDL-R) in PH is not known. Methods and Results We examined the role of LDL-R in the development of PH and determined the efficacy of high-density lipoprotein mimetic peptide 4F in mitigating PH. Explanted human lungs and plasma from patients with PH and control subjects were analyzed for gene expression, histological characteristics, and lipoprotein oxidation. Male LDL-R null (LDL-R knockout) mice (12-15 months old) were fed chow, Western diet (WD), WD with 4F, and WD with scramble peptide for 12 weeks. Serial echocardiography, cardiac catheterization, oxidized LDL assay, real-time quantitative reverse transcription-polymerase chain reaction, and histological analysis were performed. The effect of LDL-R knockdown and oxidized LDL on human pulmonary artery smooth muscle cell proliferation was assessed in vitro. LDL-R and CD36 expression levels were significantly downregulated in the lungs of patients with PH. Patients with PH also had increased lung lipid deposits, oxidized LDL, E06 immunoreactivity, and plasma oxidized LDL/LDL ratio. LDL-R knockout mice on WD developed PH, right ventricular hypertrophy, right ventricular dysfunction, pulmonary vascular remodeling, fibrosis, and lipid deposition in lungs, aortic atherosclerosis, and left ventricular dysfunction, which were prevented by 4F. Interestingly, PH in WD group preceded left ventricular dysfunction. Oxidized LDL or LDL-R knockdown significantly increased proliferation of human pulmonary artery smooth muscle cells in vitro. Conclusions Human PH is associated with decreased LDL-R in lungs and increased oxidized LDL in lungs and plasma. WD-fed LDL-R knockout mice develop PH and right ventricular dysfunction, implicating a role for LDL-R and oxidized lipids in PH.

Oral 15-Hydroxyeicosatetraenoic Acid Induces Pulmonary Hypertension in Mice by Triggering T Cell-Dependent Endothelial Cell Apoptosis.

Pulmonary arterial hypertension (PAH) is a fatal disease characterized by increased mean pulmonary arterial pressure. Elevated plasma and lung concentrations of oxidized lipids, including 15-hydroxyeicosatetraenoic acid (15-HETE), have been demonstrated in patients with PAH and animal models. We previously demonstrated that feeding mice with 15-HETE is sufficient to induce pulmonary hypertension, but the mechanisms remain unknown. RNA sequencing data from the mouse lungs on 15-HETE diet revealed significant activation of pathways involved in both antigen processing and presentation and T cell-mediated cytotoxicity. Analysis of human microarray from patients with PAH also identified activation of identical pathways compared with controls. We show that in both 15-HETE-fed mice and patients with PAH, expression of the immunoproteasome subunit 5 is significantly increased, which was concomitant with an increase in the number of CD8/CD69 (cluster of differentiation 8 / cluster of differentiation 69) double-positive cells, as well as pulmonary arterial endothelial cell apoptosis in mice. Human pulmonary arterial endothelial cells cultured with 15-HETE were more prone to apoptosis when exposed to CD8 cells. Cultured intestinal epithelial cells secreted more oxidized lipids in response to 15-HETE, which is consistent with accumulation of circulating oxidized lipids in 15-HETE-fed mice. Administration of an apoA-I (apolipoprotein A-I) mimetic peptide, Tg6F (transgenic 6F), which is known to prevent accumulation of circulating oxidized lipids, not only inhibited pulmonary arterial endothelial cell apoptosis but also prevented and rescued 15-HETE-induced pulmonary hypertension in mice. In conclusion, our results suggest that (1) 15-HETE diet induces pulmonary hypertension by a mechanism that involves oxidized lipid-mediated T cell-dependent pulmonary arterial endothelial cell apoptosis and (2) Tg6F administration may be a novel therapy for treating PAH.

Experimental Pulmonary Hypertension Is Associated With Neuroinflammation in the Spinal Cord.

RATIONALE: Pulmonary hypertension (PH) is a rare but fatal disease characterized by elevated pulmonary pressures and vascular remodeling, leading to right ventricular failure and death. Recently, neuroinflammation has been suggested to be involved in the sympathetic activation in experimental PH. Whether PH is associated with neuroinflammation in the spinal cord has never been investigated. METHODS/RESULTS: PH was well-established in adult male Wistar rats 3-week after pulmonary endothelial toxin Monocrotaline (MCT) injection. Using the thoracic segments of the spinal cord, we found a 5-fold increase for the glial fibrillary acidic protein (GFAP) in PH rats compared to controls (p < 0.05). To further determine the region of the spinal cord where GFAP was expressed, we performed immunofluorescence and found a 3 to 3.5-fold increase of GFAP marker in the gray matter, and a 2 to 3-fold increase in the white matter in the spinal cord of PH rats compared to controls. This increase was due to PH (MCT vs. Control; p < 0.01), and there was no difference between the dorsal versus ventral region. PH rats also had an increase in the pro-inflammatory marker chemokine (C-C motif) ligand 3 (CCL3) protein expression (∼ 3-fold) and (2.8 to 4-fold, p < 0.01) in the white matter. Finally, angiogenesis was increased in PH rat spinal cords assessed by the adhesion molecule CD31 expression (1.5 to 2.3-fold, p < 0.01). CONCLUSION: We report for the first time evidence for neuroinflammation in the thoracic spinal cord of pulmonary hypertensive rats. The impact of spinal cord inflammation on cardiopulmonary function in PH remains elusive.

Histological hallmarks and role of Slug/PIP axis in pulmonary hypertension secondary to pulmonary fibrosis.

Pulmonary hypertension secondary to pulmonary fibrosis (PF-PH) is one of the most common causes of PH, and there is no approved therapy. The molecular signature of PF-PH and underlying mechanism of why pulmonary hypertension (PH) develops in PF patients remains understudied and poorly understood. We observed significantly increased vascular wall thickness in both fibrotic and non-fibrotic areas of PF-PH patient lungs compared to PF patients. The increased vascular wall thickness in PF-PH patients is concomitant with a significantly increased expression of the transcription factor Slug within the macrophages and its target prolactin-induced protein (PIP), an extracellular matrix protein that induces pulmonary arterial smooth muscle cell proliferation. We developed a novel translational rat model of combined PF-PH that is reproducible and shares similar histological features (fibrosis, pulmonary vascular remodeling) and molecular features (Slug and PIP upregulation) with human PF-PH. We found Slug inhibition decreases PH severity in our animal model of PF-PH. Our study highlights the role of Slug/PIP axis in PF-PH.

Recovery and prognosticators of paralysis in West Nile virus infection.

Previous studies have demonstrated that lesions of the anterior horn motor neurons are the primary pathology in patients with paralysis due to West Nile virus (WNV) infection. To characterize recovery and identify prognostic factors for the recovery of paralysis, we investigated 11 patients with electrophysiology testing and muscle biopsy, and one with autopsy. We found that limb weakness was markedly asymmetric and differed between upper and lower extremities, suggesting focal or segmental involvement of the spinal cord anterior horn. This was supported by segmental depletion of spinal motor neurons at autopsy. Clinical recovery was variable during a 21-month follow-up period. To explain variability, we performed motor unit number estimation (MUNE) in six patients. MUNE values and strength were correlated in tested muscles. We also detected motor nerve terminal damages in muscle biopsies, suggesting another possible mechanism for transient weakness and variable recovery. We conclude that the type of pathological lesions may vary in paralytic WNV infection, and different degrees or combinations of motor neuron loss and motor nerve terminal changes may account for the observed degrees of weakness and recovery.

A case of Hashimoto's encephalopathy: association with sensory ganglionopathy.

We report a case of Hashimoto's encephalopathy with prominent unsteadiness of gait. Nerve conduction studies and electromyographic findings were consistent with a sensory ganglionopathy. Symptoms and clinical findings resolved with high-dose corticosteroid therapy and paralleled the levels of anti-microsomal antibodies. Sensory ganglionopathy seems to be another aspect of the broad clinical syndrome labeled Hashimoto's encephalopathy.