Effect of Low-Level Tragus Stimulation on Cardiac Metabolism in Heart Failure with Preserved Ejection Fraction: A Transcriptomics-Based Analysis.

Abnormal cardiac metabolism precedes and contributes to structural changes in heart failure. Low-level tragus stimulation (LLTS) can attenuate structural remodeling in heart failure with preserved ejection fraction (HFpEF). The role of LLTS on cardiac metabolism is not known. Dahl salt-sensitive rats of 7 weeks of age were randomized into three groups: low salt (0.3% NaCl) diet (control group; n = 6), high salt diet (8% NaCl) with either LLTS (active group; n = 8), or sham stimulation (sham group; n = 5). Both active and sham groups received the high salt diet for 10 weeks with active LLTS or sham stimulation (20 Hz, 2 mA, 0.2 ms) for 30 min daily for the last 4 weeks. At the endpoint, left ventricular tissue was used for RNA sequencing and transcriptomic analysis. The Ingenuity Pathway Analysis tool (IPA) was used to identify canonical metabolic pathways and upstream regulators. Principal component analysis demonstrated overlapping expression of important metabolic genes between the LLTS, and control groups compared to the sham group. Canonical metabolic pathway analysis showed downregulation of the oxidative phosphorylation (Z-score: -4.707, control vs. sham) in HFpEF and LLTS improved the oxidative phosphorylation (Z-score = -2.309, active vs. sham). HFpEF was associated with the abnormalities of metabolic upstream regulators, including PPARGC1α, insulin receptor signaling, PPARα, PPARδ, PPARGC1ß, the fatty acid transporter SLC27A2, and lysine-specific demethylase 5A (KDM5A). LLTS attenuated abnormal insulin receptor and KDM5A signaling. HFpEF is associated with abnormal cardiac metabolism. LLTS, by modulating the functioning of crucial upstream regulators, improves cardiac metabolism and mitochondrial oxidative phosphorylation.

Sex differences in the incidence and mode of death in rats with heart failure with preserved ejection fraction.

NEW FINDINGS: What is the central question of this study? Prior studies failed to address the role of sex in modifying the pathophysiology and response to therapy in heart failure with preserved ejection fraction (HFpEF), potentially introducing bias into translational findings. We aimed to explore sex differences in outcomes and sought to identify the underlying mechanisms in a well-established rat model of HFpEF. What is the main finding and its importance? Male rats with HFpEF exhibited worse survival compared with females and were at a higher risk for sudden death, attributable in part to QT prolongation, autonomic dysregulation and enhanced inflammation. These data might provide the basis for the development of sex-specific interventions in HFpEF targeting these abnormalities. ABSTRACT: Heart failure with preserved ejection fraction (HFpEF) accounts for 50% of heart failure, and sudden death is the leading cause of mortality. We aimed to explore sex differences in outcomes in rats with HFpEF and sought to identify the underlying mechanisms. Dahl salt-sensitive rats of either sex were randomized into high-salt diet (HS diet; 8% NaCl, n = 46, 50% female) or low-salt diet (LS diet; 0.3% NaCl; n = 24, 50% female) at 7 weeks of age. After 6 and 10 weeks of LS or HS diets, the ECG, heart rate variability, cytokines and echocardiographic parameters were measured. The animals were monitored daily for development of HFpEF and survival. Over 6 weeks of HS diet, rats developed significant hypertension and signs of HFpEF. Compared with female HS diet-fed rats, males exhibited more left ventricular dilatation, a longer QT interval, and worse autonomic tone, as assessed by heart rate variability and elevated inflammatory cytokines. Ten of 23 (46%) male rats died during follow-up, compared with two of 23 (9%) female rats (P = 0.01). There were four sudden deaths in males (with ventricular tachycardia documented in one rat), whereas the females died of heart failure. In conclusion, male rats with HFpEF exhibit worse survival compared with females and are at a higher risk for sudden death, attributable in part to QT prolongation, autonomic dysregulation and enhanced inflammation. These data might provide the basis for the development of sex-specific interventions in HFpEF targeting these abnormalities.

Suppressing thyroid hormone signaling preserves cone photoreceptors in mouse models of retinal degeneration.

Cone phototransduction and survival of cones in the human macula is essential for color vision and for visual acuity. Progressive cone degeneration in age-related macular degeneration, Stargardt disease, and recessive cone dystrophies is a major cause of blindness. Thyroid hormone (TH) signaling, which regulates cell proliferation, differentiation, and apoptosis, plays a central role in cone opsin expression and patterning in the retina. Here, we investigated whether TH signaling affects cone viability in inherited retinal degeneration mouse models. Retinol isomerase RPE65-deficient mice [a model of Leber congenital amaurosis (LCA) with rapid cone loss] and cone photoreceptor function loss type 1 mice (severe recessive achromatopsia) were used to determine whether suppressing TH signaling with antithyroid treatment reduces cone death. Further, cone cyclic nucleotide-gated channel B subunit-deficient mice (moderate achromatopsia) and guanylate cyclase 2e-deficient mice (LCA with slower cone loss) were used to determine whether triiodothyronine (T3) treatment (stimulating TH signaling) causes deterioration of cones. We found that cone density in retinol isomerase RPE65-deficient and cone photoreceptor function loss type 1 mice increased about sixfold following antithyroid treatment. Cone density in cone cyclic nucleotide-gated channel B subunit-deficient and guanylate cyclase 2e-deficient mice decreased about 40% following T3 treatment. The effect of TH signaling on cone viability appears to be independent of its regulation on cone opsin expression. This work demonstrates that suppressing TH signaling in retina dystrophy mouse models is protective of cones, providing insights into cone preservation and therapeutic interventions.

Blocking the adhesion cascade at the premetastatic niche for prevention of breast cancer metastasis.

Shear-resistant adhesion and extravasation of disseminated cancer cells at the target organ is a crucial step in hematogenous metastasis. We found that the vascular adhesion molecule E-selectin preferentially promoted the shear-resistant adhesion and transendothelial migration of the estrogen receptor (ER)(-)/CD44(+) hormone-independent breast cancer cells, but not of the ER(+)/CD44(-/low) hormone-dependent breast cancer cells. Coincidentally, CD44(+) breast cancer cells were abundant in metastatic lung and brain lesions in ER(-) breast cancer, suggesting that E-selectin supports hematogenous metastasis of ER(-)/CD44(+) breast cancer. In an attempt to prevent hematogenous metastasis through the inhibition of a shear-resistant adhesion of CD44(+) cancer cells to E-selectin-expressing blood vessels on the premetastatic niche, an E-selectin targeted aptamer (ESTA) was developed. We demonstrated that a single intravenous injection of ESTA reduced metastases to a baseline level in both syngeneic and xenogeneic forced breast cancer metastasis models without relocating the site of metastasis. The effect of ESTA was absent in E-selectin knockout mice, suggesting that E-selectin is a molecular target of ESTA. Our data highlight the potential application of an E-selectin antagonist for the prevention of hematogenous metastasis of ER(-)/CD44(+) breast cancer.

Loss of cone cyclic nucleotide-gated channel leads to alterations in light response modulating system and cellular stress response pathways: a gene expression profiling study.

The cone photoreceptor cyclic nucleotide-gated (CNG) channel is essential for central and color vision and visual acuity. Mutations in the channel subunits CNGA3 and CNGB3 are associated with achromatopsia and cone dystrophy. We investigated the gene expression profiles in mouse retina with CNG channel deficiency using whole genome expression microarrays. As cones comprise only 2 to 3% of the total photoreceptor population in the wild-type mouse retina, the mouse lines with CNG channel deficiency on a cone-dominant background, i.e. Cnga3-/-/Nrl-/- and Cngb3-/-/Nrl-/- mice, were used in our study. Comparative data analysis revealed a total of 105 genes altered in Cnga3-/-/Nrl-/- and 92 in Cngb3-/-/Nrl-/- retinas, relative to Nrl-/- retinas, with 27 genes changed in both genotypes. The differentially expressed genes primarily encode proteins associated with cell signaling, cellular function maintenance and gene expression. Ingenuity pathway analysis (IPA) identified 26 and 9 canonical pathways in Cnga3-/-/Nrl-/- and Cngb3-/-/Nrl-/- retinas, respectively, with 6 pathways being shared. The shared pathways include phototransduction, cAMP/PKA-mediated signaling, endothelin signaling, and EIF2/endoplasmic reticulum (ER) stress, whereas the IL-1, CREB, and purine metabolism signaling were found to specifically associate with Cnga3 deficiency. Thus, CNG channel deficiency differentially regulates genes that affect cell processes such as phototransduction, cellular survival and gene expression, and such regulations play a crucial role(s) in the retinal adaptation to impaired cone phototransduction. Though lack of Cnga3 and Cngb3 shares many common pathways, deficiency of Cnga3 causes more significant alterations in gene expression. This work provides insights into how cones respond to impaired phototransduction at the gene expression levels.

Safety evaluation of intravenously administered mono-thioated aptamer against E-selectin in mice.

The medical applications of aptamers have recently emerged. We developed an antagonistic thioaptamer (ESTA) against E-selectin. Previously, we showed that a single injection of ESTA at a dose of 100µg inhibits breast cancer metastasis in mice through the functional blockade of E-selectin. In the present study, we evaluated the safety of different doses of intravenously administered ESTA in single-dose acute and repeat-dose subacute studies in ICR mice. Our data indicated that intravenous administration of up to 500µg ESTA did not result in hematologic abnormality in either study. Additionally, intravenous injection of ESTA did not affect the levels of plasma cytokines (IL-1ß, IL-2, IL-4, IL-5, IL-6, IL-10, GM-CSF, IFN-γ, and TNF-α) or complement split products (C3a and C5a) in either study. However, repeated injections of ESTA slightly increased plasma ALT and AST activities, in accordance with the appearance of small necrotic areas in the liver. In conclusion, our data demonstrated that intravenous administration of ESTA does not cause overt hematologic, organs, and immunologic responses under the experimental conditions.

cGMP accumulation causes photoreceptor degeneration in CNG channel deficiency: evidence of cGMP cytotoxicity independently of enhanced CNG channel function.

Photoreceptor cyclic nucleotide-gated (CNG) channels regulate Ca(2+) influx in rod and cone photoreceptors. cGMP, the native ligand of the photoreceptor CNG channels, has been associated with cytotoxicity when its levels rise above normal due to defects in photoreceptor phosphodiesterase (PDE6) or regulation of retinal guanylyl cyclase (retGC). We found a massive accumulation of cGMP in CNGA3-deficient retina and investigated whether cGMP accumulation plays a role in cone degeneration in CNG channel deficiency. The time course study showed that the retinal cGMP level in Cnga3(-/-);Nrl(-/-) mice with CNGA3 deficiency on a cone-dominant background was sharply increased at postnatal day 8 (P8), peaked around P10-P15, remained high through P30-P60, and returned to near control level at P90. This elevation pattern correlated with photoreceptor apoptotic death, which peaked around P15-P20. In Cnga3(-/-);Gucy2e(-/-) mice lacking retGC1, cone density and expression levels of cone-specific proteins were significantly increased compared with Cnga3(-/-), consistent with a role of cGMP accumulation as the major contributor to cone death caused by CNG channel deficiency. The activity and expression levels of cGMP-dependent protein kinase G (PKG) were significantly increased in Cnga3(-/-);Nrl(-/-) retina compared with Nrl(-/-), suggesting an involvement of PKG regulation in cell death. Our results indicate that cGMP accumulation in photoreceptors can itself exert cytotoxic effect in cones, independently of CNG channel activity and Ca(2+) influx.

Noninvasive Vagus Nerve Stimulation in Postural Tachycardia Syndrome: A Randomized Clinical Trial.

BACKGROUND: Low-level transcutaneous stimulation of the auricular branch of the vagus nerve at the tragus is antiarrhythmic and anti-inflammatory in animals and humans. Preliminary studies show that transcutaneous vagus nerve stimulation (tVNS) is beneficial in animal models of postural tachycardia syndrome (POTS). OBJECTIVES: In this study the authors conducted a sham-controlled, double-blind, randomized clinical trial to examine the effect of tVNS on POTS over a 2-month period relative to sham stimulation. METHODS: tVNS (20 Hz, 1 mA below discomfort threshold) was delivered using an ear clip attached to either the tragus (active; n = 12) or the ear lobe (sham; n = 14) for 1 hour daily over a 2-month period. Postural tachycardia was assessed during the baseline and 2-month visit. Heart rate variability based on 5-minute electrocardiogram, serum cytokines, and antiautonomic autoantibodies were measured at the respective time points. RESULTS: Mean age was 34 ± 11 years (100% female; 81% Caucasian). Adherence to daily stimulation was 83% in the active arm and 86% in the sham arm (P > 0.05). Postural tachycardia was significantly less in the active arm compared with the sham arm at 2 months (mean postural increase in heart rate 17.6 ± 9.9 beats/min vs 31.7 ± 14.4 beats/min; P = 0.01). Antiadrenergic autoantibodies and inflammatory cytokines were lower in the active arm compared with the sham arm at 2 months (P < 0.05). Heart rate variability was better in the active arm. No device-related side effects were observed. CONCLUSIONS: Our results support the emerging paradigm of noninvasive neuromodulation to treat POTS. Mechanistically, this effect appears to be related to reduction of antiautonomic autoantibodies and inflammatory cytokines, and improvement in autonomic tone. Further studies are warranted. (Autoimmune Basis for Postural Tachycardia Syndrome; NCT05043051).

Endoplasmic reticulum stress-associated cone photoreceptor degeneration in cyclic nucleotide-gated channel deficiency.

Cyclic nucleotide-gated (CNG) channels play a pivotal role in phototransduction. Mutations in the cone CNG channel subunits CNGA3 and CNGB3 account for >70% of all known cases of achromatopsia. Cones degenerate in achromatopsia patients and in CNGA3(-/-) and CNGB3(-/-) mice. This work investigates the molecular basis of cone degeneration in CNG channel deficiency. As cones comprise only 2-3% of the total photoreceptor population in the wild-type mouse retina, we generated mouse lines with CNG channel deficiency on a cone-dominant background, i.e. CNGA3(-/-)/Nrl(-/-) and CNGB3(-/-)/Nrl(-/-) mice. The retinal phenotype and potential cell death pathways were examined by functional, biochemical, and immunohistochemical approaches. CNGA3(-/-)/Nrl(-/-) and CNGB3(-/-)/Nrl(-/-) mice showed impaired cone function, opsin mislocalization, and cone degeneration similar to that in the single knock-out mice. The endoplasmic reticulum stress marker proteins, including Grp78/Bip, phospho-eIF2α, phospho-IP(3)R, and CCAAT/enhancer-binding protein homologous protein, were elevated significantly in CNGA3(-/-)/Nrl(-/-) and CNGB3(-/-)/Nrl(-/-) retinas, compared with the age-matched (postnatal 30 days) Nrl(-/-) controls. Along with these, up-regulation of the cysteine protease calpains and cleavage of caspase-12 and caspase-7 were found in the channel-deficient retinas, suggesting an endoplasmic reticulum stress-associated apoptosis. In addition, we observed a nuclear translocation of apoptosis-inducing factor (AIF) and endonuclease G in CNGA3(-/-)/Nrl(-/-) and CNGB3(-/-)/Nrl(-/-) retinas, implying a mitochondrial insult in the endoplasmic reticulum stress-activated cell death process. Taken together, our findings suggest a crucial role of endoplasmic reticulum stress in cone degeneration associated with CNG channel deficiency.

Long-term and age-dependent restoration of visual function in a mouse model of CNGB3-associated achromatopsia following gene therapy.

Mutations in the CNGB3 gene account for >50% of all known cases of achromatopsia. Although of early onset, its stationary character and the potential for rapid assessment of restoration of retinal function following therapy renders achromatopsia a very attractive candidate for gene therapy. Here we tested the efficacy of an rAAV2/8 vector containing a human cone arrestin promoter and a human CNGB3 cDNA in CNGB3 deficient mice. Following subretinal delivery of the vector, CNGB3 was detected in both M- and S-cones and resulted in increased levels of CNGA3, increased cone density and survival, improved cone outer segment structure and normal subcellular compartmentalization of cone opsins. Therapy also resulted in long-term improvement of retinal function, with restoration of cone ERG amplitudes of up to 90% of wild-type and a significant improvement in visual acuity. Remarkably, successful restoration of cone function was observed even when treatment was initiated at 6 months of age; however, restoration of normal visual acuity was only possible in younger animals (e.g. 2-4 weeks old). This study represents achievement of the most substantial restoration of visual function reported to date in an animal model of achromatopsia using a human gene construct, which has the potential to be utilized in clinical trials.

Non-invasive Vagus Nerve Simulation in Postural Orthostatic Tachycardia Syndrome.

Postural orthostatic tachycardia syndrome (POTS) is a chronic debilitating condition of orthostatic intolerance, predominantly affecting young females. Other than postural tachycardia, symptoms of POTS include a spectrum of non-cardiac, systemic and neuropsychiatric features. Despite the availability of widespread pharmacological and non-pharmacological therapeutic options, the management of POTS remains challenging. Exaggerated parasympathetic withdrawal and sympathetic overdrive during postural stress are principal mechanisms of postural tachycardia in POTS. Non-invasive, transcutaneous, vagus nerve stimulation (tVNS) is known to restore sympathovagal balance and is emerging as a novel therapeutic strategy in cardiovascular conditions including arrhythmias and heart failure. Furthermore, tVNS also exerts immunomodulatory and anti-inflammatory effects. This review explores the effects of tVNS on the pathophysiology of POTS and its potential as an alternative non-pharmacological option in this condition.

Notch1-mediated tumor suppression in cervical cancer with the involvement of SST signaling and its application in enhanced SSTR-targeted therapeutics.

The role of Notch signaling in cervical cancer is seemingly controversial. To confirm the function of Notch signaling in this type of cancer, we established a stable Notch1-activated cervical cancer HeLa cell line. We found that Notch1 activation resulted in apoptosis, cell cycle arrest, and tumor suppression. At the molecular level, we found that a variety of genes associated with cyclic AMP, G protein-coupled receptor, and cancer signaling pathways contributed to Notch1-mediated tumor suppression. We observed that the expression of somatostatin (SST) was dramatically induced by Notch1 signaling activation, which was accompanied by enhanced expression of the cognate SST receptor subtype 1 (SSTR1) and SSTR2. Certain genes, such as tumor protein 63 (TP63, p63), were upregulated, whereas others, such as B-cell lymphoma 2 (BCL-2), Myc, Akt, and STAT3, were downregulated. Subsequently, knockdown of Notch1-induced SST reversed Notch1-induced decrease of BCL-2 and increase of p63, indicating that Notch1-induced tumor suppression may be partly through upregulating SST signaling. Our findings support a possible crosstalk between Notch signaling and SST signaling. Moreover, Notch-induced SSTR activation could enhance SSTR-targeted cancer chemotherapy. Valproic acid (VPA), a histone deacetylase inhibitor, suppressed cell growth and upregulated the expression of Notch1 and SSTR2. A combination therapy with VPA and the SSTR2-targeting cytotoxic conjugate CPT-SST strongly led to greater suppression, as compared to each alone. Our findings thus provide us with a promising clinical opportunity for enhanced cancer therapy using combinations of Notch1-activating agents and SSTR2-targeting agents.

Transcutaneous Vagus Nerve Stimulation Ameliorates the Phenotype of Heart Failure With Preserved Ejection Fraction Through Its Anti-Inflammatory Effects.

BACKGROUND: A systemic proinflammatory state plays a central role in the development of heart failure with preserved ejection fraction (HFpEF). Low-level transcutaneous vagus nerve stimulation (LLTS) suppresses inflammation in animals and humans, mediated by an α7nAchR (alpha7 nicotinic acetylcholine receptor)-dependent pathway. We examined the effects of LLTS on cardiac function, inflammation, and fibrosis in the presence of α7nAchR pharmacological blockade in a rat model of HFpEF. METHODS: Dahl salt-sensitive rats at 7 weeks of age were treated with high-salt diet for 6 weeks to induce HFpEF, followed by 4 weeks of (1) LLTS, (2) LLTS with the α7nAchR blocker methyllycaconitine, (3) sham, and (4) olmesartan. Blood pressure, cardiac function by echocardiography, heart rate variability, and serum cytokines were measured at 13 and 17 weeks of age. Cardiac fibrosis, inflammatory cell infiltration, and gene expression were determined at 17 weeks. RESULTS: LLTS attenuated the increase in blood pressure; improved cardiac function; decreased inflammatory cytokines, macrophage infiltration, and fibrosis; and improved survival compared with other groups. Methyllycaconitine attenuated these effects, whereas olmesartan did not improve cardiac function or fibrosis despite maintaining similar blood pressure as LLTS. Heart rate variability was similarly improved in the LLTS and LLTS plus methyllycaconitine groups but remained low in the other groups. LLTS reversed the dysregulated inflammatory signaling pathways in HFpEF hearts. CONCLUSIONS: Neuromodulation with LLTS improved cardiac function in a rat model of HFpEF through its anti-inflammatory and antifibrotic effects. These results provide the basis for further clinical trials in humans.

Neuromodulation of Inflammation to Treat Heart Failure With Preserved Ejection Fraction: A Pilot Randomized Clinical Trial.

Background A systemic proinflammatory state plays a central role in the development of heart failure with preserved ejection fraction. Low-level transcutaneous vagus nerve stimulation suppresses inflammation in humans. We conducted a sham-controlled, double-blind, randomized clinical trial to examine the effect of chronic low-level transcutaneous vagus nerve stimulation on cardiac function, exercise capacity, and inflammation in patients with heart failure with preserved ejection fraction. Methods and Results Patients with heart failure with preserved ejection fraction and at least 2 additional comorbidities (obesity, diabetes, hypertension, or age ≥65 years) were randomized to either active (tragus) or sham (earlobe) low-level transcutaneous vagus nerve stimulation (20 Hz, 1 mA below discomfort threshold), for 1 hour daily for 3 months. Echocardiography, 6-minute walk test, quality of life, and serum cytokines were assessed at baseline and 3 months. Fifty-two patients (mean age 70.4±9.2 years; 70% female) were included (active, n=26; sham, n=26). Baseline characteristics were balanced between the 2 arms. Adherence to the protocol of daily stimulation was >90% in both arms (P>0.05). While the early mitral inflow Doppler velocity to the early diastolic mitral annulus velocity ratio did not differ between groups, global longitudinal strain and tumor necrosis factor-α levels at 3 months were significantly improved in the active compared with the sham arm (-18.6%±2.5% versus -16.0%±2.4%, P=0.002; 8.9±2.8 pg/mL versus 11.3±2.9 pg/mL, P=0.007, respectively). The reduction in tumor necrosis factor-α levels correlated with global longitudinal strain improvement (r=-0.73, P=0.001). Quality of life was better in the active arm. No device-related side effects were observed. Conclusions Neuromodulation with low-level transcutaneous vagus nerve stimulation over 3 months resulted in a significant improvement in global longitudinal strain, inflammatory cytokines, and quality of life in patients with heart failure with preserved ejection fraction. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT03327649.

Non-invasive vagus nerve stimulation attenuates proinflammatory cytokines and augments antioxidant levels in the brainstem and forebrain regions of Dahl salt sensitive rats.

The anti-inflammatory effects of vagus nerve stimulation are well known. It has recently been shown that low-level, transcutaneous stimulation of vagus nerve at the tragus (LLTS) reduces cardiac inflammation in a rat model of heart failure with preserved ejection fraction (HFpEF). The mechanisms by which LLTS affect the central neural circuits within the brain regions that are important for the regulation of cardiac vagal tone are not clear. Female Dahl salt-sensitive rats were initially fed with either low salt (LS) or high salt (HS) diet for a period of 6 weeks, followed by sham or active stimulation (LLTS) for 30 min daily for 4 weeks. To study the central effects of LLTS, four brainstem (SP5, NAb, NTS, and RVLM) and two forebrain sites (PVN and SFO) were examined. HS diet significantly increased the gene expression of proinflammatory cytokines in the SP5 and SFO. LLTS reversed HS diet-induced changes at both these sites. Furthermore, LLTS augmented the levels of antioxidant Nrf2 in the SP5 and SFO. Taken together, these findings suggest that LLTS has central anti-inflammatory and antioxidant properties that could mediate the neuromodulation of cardiac vagal tone in the rat model of HFpEF.

TREAT AF (Transcutaneous Electrical Vagus Nerve Stimulation to Suppress Atrial Fibrillation): A Randomized Clinical Trial.

OBJECTIVES: This study was a sham-controlled, double-blind, randomized clinical trial to examine the effect of chronic low level tragus stimulation (LLTS) in patients with paroxysmal AF. BACKGROUND: Low-level transcutaneous electrical stimulation of the auricular branch of the vagus nerve at the tragus (LLTS) acutely suppresses atrial fibrillation (AF) in humans, but the chronic effect remains unknown. METHODS: LLTS (20 Hz, 1 mA below the discomfort threshold) was delivered using an ear clip attached to the tragus (active arm) (n = 26) or the ear lobe (sham control arm) (n = 27) for 1 h daily over 6 months. AF burden over 2-week periods was assessed by noninvasive continuous electrocardiogram monitoring at baseline, 3 months, and 6 months. Five-minute electrocardiography and serum were obtained at each visit to measure heart rate variability and inflammatory cytokines, respectively. RESULTS: Baseline characteristics were balanced between the 2 groups. Adherence to the stimulation protocol (≤4 sessions lost per month) was 75% in the active arm and 83% in the control arm (p > 0.05). At 6 months, the median AF burden was 85% lower in the active arm compared with the control arm (ratio of medians: 0.15; 95% confidence interval: 0.03 to 0.65; p = 0.011). Tumor necrosis factor-alpha was significantly decreased by 23% in the active group relative to the control group (ratio of medians: 0.77; 95% confidence interval: 0.63 to 0.94; p = 0.0093). Frequency domain indices of heart rate variability were significantly altered with active versus control stimulation (p < 0.01). No device-related side effects were observed. CONCLUSIONS: Chronic, intermittent LLTS resulted in lower AF burden than did sham control stimulation, supporting its use to treat paroxysmal AF in selected patients. (Transcutaneous Electrical Vagus Nerve Stimulation to Suppress Atrial Fibrillation [TREAT-AF]; NCT02548754).

CNGA3 deficiency affects cone synaptic terminal structure and function and leads to secondary rod dysfunction and degeneration.

PURPOSE: To investigate rod function and survival after cone dysfunction and degeneration in a mouse model of cone cyclic nucleotide-gated (CNG) channel deficiency. METHODS: Rod function and survival in mice with cone CNG channel subunit CNGA3 deficiency (CNGA3-/- mice) were evaluated by electroretinographic (ERG), morphometric, and Western blot analyses. The arrangement, integrity, and ultrastructure of photoreceptor terminals were investigated by immunohistochemistry and electron microscopy. RESULTS: The authors found loss of cone function and cone death accompanied by impairment of rods and rod-driven signaling in CNGA3-/- mice. Scotopic ERG b-wave amplitudes were reduced by 15% at 1 month, 30% at 6 months, and 40% at 9 months and older, while scotopic a-wave amplitudes were decreased by 20% at 9 months, compared with ERGs of age-matched wild-type mice. Outer nuclear layer thickness in CNGA3-/- retina was reduced by 15% at 12 months compared with age-matched wild-type controls. This was accompanied by a 30%-40% reduction in expression of rod-specific proteins, including rhodopsin, rod transducin α-subunit, and glutamic acid-rich protein (GARP). Cone terminals in the CNGA3-/- retina showed a progressive loss of neurochemical and ultrastructural integrity. Abnormalities were observed as early as 1 month. Disorganized rod terminal ultrastructure was noted by 12 months. CONCLUSIONS: These findings demonstrate secondary rod impairment and degeneration after cone degeneration in mice with cone CNG channel deficiency. Loss of cone phototransduction accompanies the compromised integrity of cone terminals. With time, rod synaptic structure, function, and viability also become compromised.

Early-onset, slow progression of cone photoreceptor dysfunction and degeneration in CNG channel subunit CNGB3 deficiency.

PURPOSE: To investigate the progression of cone dysfunction and degeneration in CNG channel subunit CNGB3 deficiency. METHODS: Retinal structure and function in CNGB3(-/-) and wild-type (WT) mice were evaluated by electroretinography (ERG), lectin cytochemistry, and correlative Western blot analysis of cone-specific proteins. Cone and rod terminal integrity was assessed by electron microscopy and synaptic protein immunohistochemical distribution. RESULTS: Cone ERG amplitudes (photopic b-wave) in CNGB3(-/-) mice were reduced to approximately 50% of WT levels by postnatal day 15, decreasing further to approximately 30% of WT levels by 1 month and to approximately 20% by 12 months of age. Rod ERG responses (scotopic a-wave) were not affected in CNGB3(-/-) mice. Average CNGB3(-/-) cone densities were approximately 80% of WT levels at 1 month and declined slowly thereafter to only approximately 50% of WT levels by 12 months. Expression levels of M-opsin, cone transducin α-subunit, and cone arrestin in CNGB3(-/-) mice were reduced by 50% to 60% by 1 month and declined to 35% to 45% of WT levels by 9 months. In addition, cone opsin mislocalized to the outer nuclear layer and the outer plexiform layer in the CNGB3(-/-) retina. Cone and rod synaptic marker expression and terminal ultrastructure were normal in the CNGB3(-/-) retina. CONCLUSIONS: These findings are consistent with an early-onset, slow progression of cone functional defects and cone loss in CNGB3(-/-) mice, with the cone signaling deficits arising from disrupted phototransduction and cone loss rather than from synaptic defects.

Investigation of cancer cell lines for peptide receptor-targeted drug development.

Many tumors highly express specific populations of G-protein-coupled receptors (GPCRs) that could be utilized for receptor-targeted therapy. We confirmed significant quantities of mRNAs specific for certain somatostatin (SST), vasoactive intestinal peptide (VIP), and bombesin (BN) receptors in various commercially available tumor cell lines. Very few of the tumor cell lines examined displayed the high receptor-binding affinity despite exhibiting the expression of appropriate mRNAs and proteins of the cognate receptors. However, binding assays establish that some tumor cell lines, such as pancreatic cancer CFPAC-1, prostate cancer DU-145, and pancreatic carcinoid BON, demonstrate high BN receptor binding. BON cells also demonstrate high somatostatin receptor (SSTR) affinity binding. We also found that tumor cell lines, such as BON and host cells expressing SST receptor subtypes 1 or 2 (CHO-R1 or CHO-R2), underwent a decrease in cell surface receptor density in multiple passages. BON and CHO-R2 cells also rapidly internalize a significant proportion of cell surface ligand-receptor complexes. The tumor cells CFPAC-1, DU-145, and BON with high receptor binding could be useful for peptide drug studies. BON cells were further applied to test SST/BN analogs and cytotoxic conjugates. Furthermore, the in vivo antitumor assay showed that the cytotoxic conjugate CPT-SST targeting all SSTR subtypes displayed a potent tumor-suppressive ability to BON tumors expressing multiple SSTR subtypes.