Abstract
Aims
C-type natriuretic peptide (CNP) is an essential endothelium-derived signalling species that governs vascular homoeostasis; CNP is also expressed in the heart but an intrinsic role for ...the peptide in cardiac function is not established. Herein, we employ unique transgenic strains with cell-specific deletion of CNP to define a central (patho)physiological capacity of CNP in maintaining heart morphology and contractility.
Methods and results
Cardiac structure and function were explored in wild type (WT), cardiomyocyte (cmCNP−/−), endothelium (ecCNP−/−), and fibroblast (fbCNP−/−)—specific CNP knockout mice, and global natriuretic peptide receptor (NPR)-B−/−, and NPR-C−/− animals at baseline and in experimental models of myocardial infarction and heart failure (HF). Endothelium-specific deletion of CNP resulted in impaired coronary responsiveness to endothelium-dependent- and flow-mediated-dilatation; changes mirrored in NPR-C−/− mice. Ex vivo, global ischaemia resulted in larger infarcts and diminished functional recovery in cmCNP−/− and NPR-C−/−, but not ecCNP−/−, vs. WT. The cardiac phenotype of cmCNP−/−, fbCNP−/−, and NPR-C−/− (but not ecCNP−/− or NPR-B−/−) mice was more severe in pressure overload- and sympathetic hyperactivation-induced HF compared with WT; these adverse effects were rescued by pharmacological CNP administration in WT, but not NPR-C−/−, mice. At a molecular level, CNP/NPR-C signalling is impaired in human HF but attenuates activation of well-validated pro-hypertrophic and pro-fibrotic pathways.
Conclusion
C-type natriuretic peptide of cardiomyocyte, endothelial and fibroblast origins co-ordinates and preserves cardiac structure, function, and coronary vasoreactivity via activation of NPR-C. Targeting NPR-C may prove an innovative approach to treating HF and ischaemic cardiovascular disorders.
BACKGROUND:Angiogenesis and vascular remodeling are complementary, innate responses to ischemic cardiovascular events, including peripheral artery disease and myocardial infarction, which restore ...tissue blood supply and oxygenation; the endothelium plays a critical function in these intrinsic protective processes. C-type natriuretic peptide (CNP) is a fundamental endothelial signaling species that coordinates vascular homeostasis. Herein, we sought to delineate a central role for CNP in angiogenesis and vascular remodeling in response to ischemia.
METHODS:The in vitro angiogenic capacity of CNP was examined in pulmonary microvascular endothelial cells and aortic rings isolated from wild-type, endothelium-specific CNP, global natriuretic peptide receptor (NPR)-B and NPR-C animals, and human umbilical vein endothelial cells. These studies were complemented by in vivo investigation of neovascularization and vascular remodeling after ischemia or vessel injury, and CNP/NPR-C expression and localization in tissue from patients with peripheral artery disease.
RESULTS:Clinical vascular ischemia is associated with reduced levels of CNP and its cognate NPR-C. Moreover, genetic or pharmacological inhibition of CNP and NPR-C, but not NPR-B, reduces the angiogenic potential of pulmonary microvascular endothelial cells, human umbilical vein endothelial cells, and isolated vessels ex vivo. Angiogenesis and remodeling are impaired in vivo in endothelium-specific CNP and NPR-C, but not NPR-B, mice; the detrimental phenotype caused by genetic deletion of endothelial CNP, but not NPR-C, can be rescued by pharmacological administration of CNP. The proangiogenic effect of CNP/NPR-C is dependent on activation of Gi, ERK1/2, and phosphoinositide 3-kinase γ/Akt at a molecular level.
CONCLUSIONS:These data define a central (patho)physiological role for CNP in angiogenesis and vascular remodeling in response to ischemia and provide the rationale for pharmacological activation of NPR-C as an innovative approach to treating peripheral artery disease and ischemic cardiovascular disorders.
The cold-induced vascular response, consisting of vasoconstriction followed by vasodilatation, is critical for protecting the cutaneous tissues against cold injury. Whilst this physiological reflex ...response is historic knowledge, the mechanisms involved are unclear. Here by using a murine model of local environmental cold exposure, we show that TRPA1 acts as a primary vascular cold sensor, as determined through TRPA1 pharmacological antagonism or gene deletion. The initial cold-induced vasoconstriction is mediated via TRPA1-dependent superoxide production that stimulates α2C-adrenoceptors and Rho-kinase-mediated MLC phosphorylation, downstream of TRPA1 activation. The subsequent restorative blood flow component is also dependent on TRPA1 activation being mediated by sensory nerve-derived dilator neuropeptides CGRP and substance P, and also nNOS-derived NO. The results allow a new understanding of the importance of TRPA1 in cold exposure and provide impetus for further research into developing therapeutic agents aimed at the local protection of the skin in disease and adverse climates.
Reliable measurement of blood pressure in conscious mice is essential in cardiovascular research. Telemetry, the "gold-standard" technique, is invasive and expensive and therefore tail-cuff, a ...noninvasive alternative, is widely used. However, tail-cuff requires handling and restraint during measurement, which may cause stress affecting blood pressure and undermining reliability of the results.
C57Bl/6J mice were implanted with radio-telemetry probes to investigate the effects of the steps of the tail-cuff technique on central blood pressure, heart rate, and temperature. This included comparison of handling techniques, operator's sex, habituation, and influence of hypertension induced by angiotensin II. Direct comparison of measurements obtained by telemetry and tail-cuff were made in the same mouse. The results revealed significant increases in central blood pressure, heart rate, and core body temperature from baseline following handling interventions without significant difference among the different handling technique, habituation, or sex of the investigator. Restraint induced the largest and sustained increase in cardiovascular parameters and temperature. The tail-cuff readings significantly underestimated those from simultaneous telemetry recordings; however, "nonsimultaneous" telemetry, obtained in undisturbed mice, were similar to tail-cuff readings obtained in undisturbed mice on the same day.
This study reveals that the tail-cuff technique underestimates the core blood pressure changes that occur simultaneously during the restraint and measurement phases. However, the measurements between the 2 techniques are similar when tail-cuff readings are compared with telemetry readings in the nondisturbed mice. The differences between the simultaneous recordings by the 2 techniques should be recognized by researchers.
Transient receptor potential canonical 5 (TRPC5) is functionally expressed on a range of cells including fibroblast-like synoviocytes, which play an important role in arthritis. A role for TRPC5 in ...inflammation has not been previously shown in vivo. We investigated the contribution of TRPC5 in arthritis.
Male wild-type and TRPC5 knockout (KO) mice were used in a complete Freund's adjuvant (CFA)-induced unilateral arthritis model, assessed over 14 days. Arthritis was determined by measurement of knee joint diameter, hindlimb weightbearing asymmetry and pain behaviour. Separate studies involved chronic pharmacological antagonism of TRPC5 channels. Synovium from human postmortem control and inflammatory arthritis samples were investigated for TRPC5 gene expression.
At baseline, no differences were observed. CFA-induced arthritis resulted in increased synovitis in TRPC5 KO mice assessed by histology. Additionally, TRPC5 KO mice demonstrated reduced ispilateral weightbearing and nociceptive thresholds (thermal and mechanical) following CFA-induced arthritis. This was associated with increased mRNA expression of inflammatory mediators in the ipsilateral synovium and increased concentration of cytokines in synovial lavage fluid. Chronic treatment with ML204, a TRPC5 antagonist, augmented weightbearing asymmetry, secondary hyperalgesia and cytokine concentrations in the synovial lavage fluid. Synovia from human inflammatory arthritis demonstrated a reduction in TRPC5 mRNA expression.
Genetic deletion or pharmacological blockade of TRPC5 results in an enhancement in joint inflammation and hyperalgesia. Our results suggest that activation of TRPC5 may be associated with an endogenous anti-inflammatory/analgesic pathway in inflammatory joint conditions.
Neurovascular Aspects of Skin Neurogenic Inflammation Aubdool, Aisah A.; Brain, Susan D.
The Journal of investigative dermatology symposium proceedings,
December 2011, 2011-Dec, 2011-12-00, 20111201, Volume:
15, Issue:
1
Journal Article
Peer reviewed
Open access
Neurogenic inflammation is involved in skin inflammation. It is hypothesized that it is involved in the pathogenesis of the common chronic cutaneous vascular disorder rosacea, but the exact mechanism ...of action is currently unknown. Transient receptor potential vanilloid 1 (TRPV1) and ankyrin 1 (TRPA1) are widely expressed on primary sensory neuron endings and non-neuronal cells such as keratinocytes. Here we describe the potential for TRPV1 and TRPA1 receptors to be involved in the pathophysiology of rosacea due to their polymodal activation, including cold and hot temperature, pungent products from vegetable and spices, reactive oxygen species, and mechanical stimuli. We discuss the role of both receptors and the sensory neuropeptides that they release in inflammation and pain sensation and evidence suggesting that both TRPV1 and TRPA1 receptors may be promising therapeutic targets for the treatment of the inflammatory symptoms of rosacea.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Background and Purpose
Transient receptor potential ankyrin‐1 (TRPA1) activation is known to mediate neurogenic vasodilatation. We investigated the mechanisms involved in TRPA1‐mediated peripheral ...vasodilatation in vivo using the TRPA1 agonist cinnamaldehyde.
Experimental Approach
Changes in vascular ear blood flow were measured in anaesthetized mice using laser Doppler flowmetry.
Key Results
Topical application of cinnamaldehyde to the mouse ear caused a significant increase in blood flow in the skin of anaesthetized wild‐type (WT) mice but not in TRPA1 knockout (KO) mice. Cinnamaldehyde‐induced vasodilatation was inhibited by the pharmacological blockade of the potent microvascular vasodilator neuropeptide CGRP and neuronal NOS‐derived NO pathways. Cinnamaldehyde‐mediated vasodilatation was significantly reduced by treatment with reactive oxygen nitrogen species (RONS) scavenger such as catalase and the SOD mimetic TEMPOL, supporting a role of RONS in the downstream vasodilator TRPA1‐mediated response. Co‐treatment with a non‐selective NOS inhibitor L‐NAME and antioxidant apocynin further inhibited the TRPA1‐mediated vasodilatation. Cinnamaldehyde treatment induced the generation of peroxynitrite that was blocked by the peroxynitrite scavenger FeTPPS and shown to be dependent on TRPA1, as reflected by an increase in protein tyrosine nitration in the skin of WT, but not in TRPA1 KO mice.
Conclusion and Implications
This study provides in vivo evidence that TRPA1‐induced vasodilatation mediated by cinnamaldehyde requires neuronal NOS‐derived NO, in addition to the traditional neuropeptide component. A novel role of peroxynitrite is revealed, which is generated downstream of TRPA1 activation by cinnamaldehyde. This mechanistic pathway underlying TRPA1‐mediated vasodilatation may be important in understanding the role of TRPA1 in pathophysiological situations.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
Thermogenesis and adipogenesis are tightly regulated mechanisms that maintain lipid homeostasis and energy balance; dysfunction of these critical processes underpins obesity and contributes to ...cardiometabolic disease. C-type natriuretic peptide (CNP) fulfills a multimodal protective role in the cardiovascular system governing local blood flow, angiogenesis, cardiac function, and immune cell reactivity. Herein, we investigated a parallel, preservative function for CNP in coordinating metabolic homeostasis. Global inducible CNP knockout mice exhibited reduced body weight, higher temperature, lower adiposity, and greater energy expenditure in vivo. This thermogenic phenotype was associated with increased expression of uncoupling protein-1 and preferential lipid utilization by mitochondria, a switch corroborated by a corresponding diminution of insulin secretion and glucose clearance. Complementary studies in isolated murine and human adipocytes revealed that CNP exerts these metabolic regulatory actions by inhibiting sympathetic thermogenic programming via Gi-coupled natriuretic peptide receptor (NPR)-C and reducing peroxisome proliferator-activated receptor-γ coactivator-1α expression, while concomitantly driving adipogenesis via NPR-B/protein kinase-G. Finally, we identified an association between CNP/NPR-C expression and obesity in patient samples. These findings establish a pivotal physiological role for CNP as a metabolic switch to balance energy homeostasis. Pharmacological targeting of these receptors may offer therapeutic utility in the metabolic syndrome and related cardiovascular disorders.
ABSTRACT
Transient receptor potential vanilloid 1 (TRPV1) is involved in sensory nerve nociceptive signaling. Recently, it has been discovered that TRPV1 receptors also regulate basal body ...temperature in multiple species from mice to humans. In the present study, we investigated whether TRPV1 modulates basal sympathetic nervous system (SNS) activity. C57BL6/J wild‐type (WT) mice and TRPV1 knockout (KO) mice were implanted with radiotelemetry probes for measurement of core body temperature. AMG 9810∗∗∗ (50 mg/kg) or vehicle (2% DMSO/5% Tween 80/10 ml/kg saline) was injected intraperitoneally. Adrenoceptor antagonists or vehicle (5 ml/kg saline) was injected subcutaneously. In WT mice, the TRPV1 antagonist, AMG9810, caused significant hyperthermia, associated with increased noradrenaline concentrations in brown adipose tissue. The hyperthermia was significantly attenuated by the β‐adrenoceptor antagonist propranolol, the mixed α‐/β‐adrenoceptor antagonist labetalol, and the α1‐adrenoceptor antagonist prazosin. TRPV1 KO mice have a normal basal body temperature, indicative of developmental compensation. D‐Amphetamine (potent sympathomimetic) caused hyperthermia in WT mice, which was reduced in TRPV1 KO mice, suggesting a decreased sympathetic drive in KOs. This study provides new evidence that TRPV1 controls thermoregulation upstream of the SNS, providing a potential therapeutic target for sympathetic hyperactivity thermoregulatory disorders.—Alawi, K. M., Aubdool, A. A., Liang, L., Wilde, E., Vepa, A., Psefteli, M.‐P., Brain, S. D., Keeble, J. E. The sympathetic nervous system is controlled by transient receptor potential vanilloid 1 in the regulation of body temperature. FASEB J. 29, 4285‐4298 (2015). www.fasebj.org
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Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
BACKGROUND:Research into the therapeutic potential of α-calcitonin gene–related peptide (α-CGRP) has been limited because of its peptide nature and short half-life. Here, we evaluate whether a novel ...potent and long-lasting (t½ ≥7 hours) acylated α-CGRP analogue (αAnalogue) could alleviate and reverse cardiovascular disease in 2 distinct murine models of hypertension and heart failure in vivo.
METHODS:The ability of the αAnalogue to act selectively via the CGRP pathway was shown in skin by using a CGRP receptor antagonist. The effect of the αAnalogue on angiotensin II–induced hypertension was investigated over 14 days. Blood pressure was measured by radiotelemetry. The ability of the αAnalogue to modulate heart failure was studied in an abdominal aortic constriction model of murine cardiac hypertrophy and heart failure over 5 weeks. Extensive ex vivo analysis was performed via RNA analysis, Western blot, and histology.
RESULTS:The angiotensin II–induced hypertension was attenuated by cotreatment with the αAnalogue (50 nmol·kg·d, SC, at a dose selected for lack of long-term hypotensive effects at baseline). The αAnalogue protected against vascular, renal, and cardiac dysfunction, characterized by reduced hypertrophy and biomarkers of fibrosis, remodeling, inflammation, and oxidative stress. In a separate study, the αAnalogue reversed angiotensin II–induced hypertension and associated vascular and cardiac damage. The αAnalogue was effective over 5 weeks in a murine model of cardiac hypertrophy and heart failure. It preserved heart function, assessed by echocardiography, while protecting against adverse cardiac remodeling and apoptosis. Moreover, treatment with the αAnalogue was well tolerated with neither signs of desensitization nor behavioral changes.
CONCLUSIONS:These findings, in 2 distinct models, provide the first evidence for the therapeutic potential of a stabilized αAnalogue, by mediating (1) antihypertensive effects, (2) attenuating cardiac remodeling, and (3) increasing angiogenesis and cell survival to protect against and limit damage associated with the progression of cardiovascular diseases. This indicates the therapeutic potential of the CGRP pathway and the possibility that this injectable CGRP analogue may be effective in cardiac disease.
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