Novel airway smooth muscle-mast cell interactions and a role for the TRPV4-ATP axis in non-atopic asthma.

Mast cell-airway smooth muscle (ASM) interactions play a major role in the immunoglobulin (Ig)E- dependent bronchoconstriction seen in asthma but less is known about IgE-independent mechanisms of mast cell activation. Transient receptor potential cation channel, subfamily V, member 4 (TRPV4) activation causes contraction of human ASM via the release of cysteinyl leukotrienes (cysLTs) but the mechanism is unknown. The objective of the present study was to investigate a role for IgE-independent, mast cell-ASM interaction in TRPV4-induced bronchospasm.Bronchoconstriction was measured in anaesthetised guinea pigs and contraction of human and guinea-pig airway tissue assessed using isometric tension measurements. Increases in intracellular [Ca2+] were imaged using the Ca2+-sensitive dye FURA2, and time-lapse ptychography was utilised as a surrogate for contraction of ASM cells.The TRPV4 agonist GSK1016790A caused contraction in vivo in the guinea pig, and in human and guinea-pig tracheal tissue, which was inhibited by the TRPV4 antagonist GSK2193874. GSK1016790A increased [Ca2+]i and released ATP in human ASM cells without causing contraction. TRPV4 and ATP evoked contraction in isolated tracheal tissue but co-culture experiments indicated a requirement for human lung mast cells. Expression profiling and pharmacological studies demonstrated that mast cell activation was dependent upon ATP activating the P2X4 receptor. Trypsin was shown to evoke contraction of tracheal tissue via activation of PAR-2-TRPV4-ATP-cysLT axis indicating the potential disease relevance of this signalling pathway.TRPV4 activation increases [Ca2+]i and releases ATP from ASM cells triggering P2X4-dependent release of cysLTs from mast cells resulting in ASM contraction. This study delineates a novel mast cell-ASM interaction and TRPV4 as a driver of IgE-independent mast cell-dependent bronchospasm.

Mechanistic link between diesel exhaust particles and respiratory reflexes.

BACKGROUND: Diesel exhaust particles (DEPs) are a major component of particulate matter in Europe's largest cities, and epidemiologic evidence links exposure with respiratory symptoms and asthma exacerbations. Respiratory reflexes are responsible for symptoms and are regulated by vagal afferent nerves, which innervate the airway. It is not known how DEP exposure activates airway afferents to elicit symptoms, such as cough and bronchospasm. OBJECTIVE: We sought to identify the mechanisms involved in activation of airway sensory afferents by DEPs. METHODS: In this study we use in vitro and in vivo electrophysiologic techniques, including a unique model that assesses depolarization (a marker of sensory nerve activation) of human vagus. RESULTS: We demonstrate a direct interaction between DEP and airway C-fiber afferents. In anesthetized guinea pigs intratracheal administration of DEPs activated airway C-fibers. The organic extract (DEP-OE) and not the cleaned particles evoked depolarization of guinea pig and human vagus, and this was inhibited by a transient receptor potential ankyrin-1 antagonist and the antioxidant N-acetyl cysteine. Polycyclic aromatic hydrocarbons, major constituents of DEPs, were implicated in this process through activation of the aryl hydrocarbon receptor and subsequent mitochondrial reactive oxygen species production, which is known to activate transient receptor potential ankyrin-1 on nociceptive C-fibers. CONCLUSIONS: This study provides the first mechanistic insights into how exposure to urban air pollution leads to activation of guinea pig and human sensory nerves, which are responsible for respiratory symptoms. Mechanistic information will enable the development of appropriate therapeutic interventions and mitigation strategies for those susceptible subjects who are most at risk.

Targeting fatty acid amide hydrolase as a therapeutic strategy for antitussive therapy.

Cough is the most common reason to visit a primary care physician, yet it remains an unmet medical need. Fatty acid amide hydrolase (FAAH) is an enzyme that breaks down endocannabinoids, and inhibition of FAAH produces analgesic and anti-inflammatory effects. Cannabinoids inhibit vagal sensory nerve activation and the cough reflex, so it was hypothesised that FAAH inhibition would produce antitussive activity via elevation of endocannabinoids.Primary vagal ganglia neurons, tissue bioassay, in vivo electrophysiology and a conscious guinea pig cough model were utilised to investigate a role for fatty acid amides in modulating sensory nerve activation in vagal afferents.FAAH inhibition produced antitussive activity in guinea pigs with concomitant plasma elevation of the fatty acid amides N-arachidonoylethanolamide (anandamide), palmitoylethanolamide, N-oleoylethanolamide and linoleoylethanolamide. Palmitoylethanolamide inhibited tussive stimulus-induced activation of guinea pig airway innervating vagal ganglia neurons, depolarisation of guinea pig and human vagus, and firing of C-fibre afferents. These effects were mediated via a cannabinoid CB2/Gi/o-coupled pathway and activation of protein phosphatase 2A, resulting in increased calcium sensitivity of calcium-activated potassium channels.These findings identify FAAH inhibition as a target for the development of novel, antitussive agents without the undesirable side-effects of direct cannabinoid receptor agonists.

XEN-D0501, a Novel Transient Receptor Potential Vanilloid 1 Antagonist, Does Not Reduce Cough in Patients with Refractory Cough.

RATIONALE: Heightened cough responses to inhaled capsaicin, a transient receptor potential vanilloid 1 (TRPV1) agonist, are characteristic of patients with chronic cough. However, previously, a TRPV1 antagonist (SB-705498) failed to improve spontaneous cough frequency in these patients, despite small reductions in capsaicin-evoked cough. OBJECTIVES: XEN-D0501 (a potent TRPV1 antagonist) was compared with SB-705498 in preclinical studies to establish whether an improved efficacy profile would support a further clinical trial of XEN-D0501 in refractory chronic cough. METHODS: XEN-D0501 and SB-705498 were profiled against capsaicin in a sensory nerve activation assay and in vivo potency established against capsaicin-induced cough in the guinea pig. Twenty patients with refractory chronic cough participated in a double-blind, randomized, placebo-controlled crossover study evaluating the effect of 14 days of XEN-D0501 (oral, 4 mg twice daily) versus placebo on awake cough frequency (primary outcome), capsaicin-evoked cough, and patient-reported outcomes. MEASUREMENTS AND MAIN RESULTS: XEN-D0501 was more efficacious and 1,000-fold more potent than SB-705498 at inhibiting capsaicin-induced depolarization of guinea pig and human isolated vagus nerve. In vivo XEN-D0501 completely inhibited capsaicin-induced cough, whereas 100 times more SB-705498 was required to achieve the same effect. In patients, XEN-D0501 substantially reduced maximal cough responses to capsaicin (mean change from baseline, XEN-D0501, -19.3 ± 16.4) coughs; placebo, -1.8 ± 5.8 coughs; P < 0.0001), but not spontaneous awake cough frequency (mean change from baseline, XEN-D0501, 6.7 ± 16.9 coughs/h; placebo, 0.4 ± 13.7 coughs/h; P = 0.41). CONCLUSIONS: XEN-D0501 demonstrated superior efficacy and potency in preclinical and clinical capsaicin challenge studies; despite this improved pharmacodynamic profile, spontaneous cough frequency did not improve, ruling out TRPV1 as an effective therapeutic target for refractory cough. Clinical trial registered with www.clinicaltrialsregister.eu (2014-000306-36).

Cigarette smoke extract (CSE) induces transient receptor potential ankyrin 1(TRPA1) expression via activation of HIF1αin A549 cells.

We previously found that transient receptor potential ankyrin 1 (TRPA1) in guinea pig tracheal epithelial cells was elevated after 14 days of cigarette smoke (CS) exposure. However, the mechanism underlying CS-induced TRPA1 expression remains unknown. Here, we explored whether cigarette smoke extract (CSE)-induced TRPA1 expression is related with modulation of HIF1α in A549 cells. Our results showed that CSE increased TRPA1 expression in A549 cells, decreased Iκ B, PHD2, and HDAC2, and increased ROS release and nuclear translocation of NF-κ B and HIF1α. Moreover, HIF1α siRNA and/or MG132 (a proteasome inhibitor) pretreatment significantly inhibited CSE-induced TRPA1 expression and HIF1α nuclear translocation in A549 cells. However, HIF1α siRNA pretreatment did not affect CSE-induced NF-κ B nuclear translocation, suggesting that CSE-induced TRPA1 expression in A549 cells is directly mediated by HIF1α, but not by NF-κ B. Similar to CSE treatment, treatment of A549 cells with LPS caused significant increases in nuclear translocation of NF-κ B and HIF1α mRNA expression, but did not alter TRPA1 mRNA expression. However, pretreatment with PHD2 siRNA did result in increased TRPA1 mRNA expression in LPS-treated A549 cells; an effect that was inhibited by SN50 (a NF-κ B inhibitor). It suggests a role for NF-κ B to indirectly regulate TRPA1 mRNA expression via modulating HIF1α mRNA transcription. In addition, treatment cells with HDAC2 siRNA plus 2%CSE resulted in increased HIF1α nuclear translocation and TRPA1 expression, which was significantly inhibited by MG132 and HIF1α siRNA. These results suggest that HDAC2 indirectly modulates TRPA1 expression by promoting the DNA-binding activity of HIF1α. These findings show that CSE increases TRPA1 expression in airway epithelial cells by directly activating HIF1α, and that this increase in TRPA1 expression is indirectly regulated via NF-κ B, PHD2 and HDAC2 modulation of HIF1α activity.

Transient receptor potential cation channel, subfamily V, member 4 and airway sensory afferent activation: Role of adenosine triphosphate.

BACKGROUND: Sensory nerves innervating the airways play an important role in regulating various cardiopulmonary functions, maintaining homeostasis under healthy conditions and contributing to pathophysiology in disease states. Hypo-osmotic solutions elicit sensory reflexes, including cough, and are a potent stimulus for airway narrowing in asthmatic patients, but the mechanisms involved are not known. Transient receptor potential cation channel, subfamily V, member 4 (TRPV4) is widely expressed in the respiratory tract, but its role as a peripheral nociceptor has not been explored. OBJECTIVE: We hypothesized that TRPV4 is expressed on airway afferents and is a key osmosensor initiating reflex events in the lung. METHODS: We used guinea pig primary cells, tissue bioassay, in vivo electrophysiology, and a guinea pig conscious cough model to investigate a role for TRPV4 in mediating sensory nerve activation in vagal afferents and the possible downstream signaling mechanisms. Human vagus nerve was used to confirm key observations in animal tissues. RESULTS: Here we show TRPV4-induced activation of guinea pig airway-specific primary nodose ganglion cells. TRPV4 ligands and hypo-osmotic solutions caused depolarization of murine, guinea pig, and human vagus and firing of Aδ-fibers (not C-fibers), which was inhibited by TRPV4 and P2X3 receptor antagonists. Both antagonists blocked TRPV4-induced cough. CONCLUSION: This study identifies the TRPV4-ATP-P2X3 interaction as a key osmosensing pathway involved in airway sensory nerve reflexes. The absence of TRPV4-ATP-mediated effects on C-fibers indicates a distinct neurobiology for this ion channel and implicates TRPV4 as a novel therapeutic target for neuronal hyperresponsiveness in the airways and symptoms, such as cough.

Neurophenotypes in Airway Diseases. Insights from Translational Cough Studies.

RATIONALE: Most airway diseases, including chronic obstructive pulmonary disease (COPD), are associated with excessive coughing. The extent to which this may be a consequence of increased activation of vagal afferents by pathology in the airways (e.g., inflammatory mediators, excessive mucus) or an altered neuronal phenotype is unknown. Understanding whether respiratory diseases are associated with dysfunction of airway sensory nerves has the potential to identify novel therapeutic targets. OBJECTIVES: To assess the changes in cough responses to a range of inhaled irritants in COPD and model these in animals to investigate the underlying mechanisms. METHODS: Cough responses to inhaled stimuli in patients with COPD, healthy smokers, refractory chronic cough, asthma, and healthy volunteers were assessed and compared with vagus/airway nerve and cough responses in a cigarette smoke (CS) exposure guinea pig model. MEASUREMENTS AND MAIN RESULTS: Patients with COPD had heightened cough responses to capsaicin but reduced responses to prostaglandin E2 compared with healthy volunteers. Furthermore, the different patient groups all exhibited different patterns of modulation of cough responses. Consistent with these findings, capsaicin caused a greater number of coughs in CS-exposed guinea pigs than in control animals; similar increased responses were observed in ex vivo vagus nerve and neuron cell bodies in the vagal ganglia. However, responses to prostaglandin E2 were decreased by CS exposure. CONCLUSIONS: CS exposure is capable of inducing responses consistent with phenotypic switching in airway sensory nerves comparable with the cough responses observed in patients with COPD. Moreover, the differing profiles of cough responses support the concept of disease-specific neurophenotypes in airway disease. Clinical trial registered with www.clinicaltrials.gov (NCT 01297790).

Prostaglandin D2 and the role of the DP1, DP2 and TP receptors in the control of airway reflex events.

Prostaglandin D2 (PGD2) causes cough and levels are increased in asthma suggesting that it may contribute to symptoms. Although the prostaglandin D2 receptor 2 (DP2) is a target for numerous drug discovery programmes little is known about the actions of PGD2 on sensory nerves and cough. We used human and guinea pig bioassays, in vivo electrophysiology and a guinea pig conscious cough model to assess the effect of prostaglandin D2 receptor (DP1), DP2 and thromboxane receptor antagonism on PGD2 responses. PGD2 caused cough in a conscious guinea pig model and an increase in calcium in airway jugular ganglia. Using pharmacology and receptor-deficient mice we showed that the DP1 receptor mediates sensory nerve activation in mouse, guinea pig and human vagal afferents. In vivo, PGD2 and a DP1 receptor agonist, but not a DP2 receptor agonist, activated single airway C-fibres. Interestingly, activation of DP2 inhibited sensory nerve firing to capsaicin in vitro and in vivo. The DP1 receptor could be a therapeutic target for symptoms associated with asthma. Where endogenous PGD2 levels are elevated, loss of DP2 receptor-mediated inhibition of sensory nerves may lead to an increase in vagally associated symptoms and the potential for such adverse effects should be investigated in clinical studies with DP2 antagonists.

The role of adenylyl cyclase isoform 6 in ß-adrenoceptor signalling in murine airways.

BACKGROUND AND PURPOSE: Adenylyl cyclase (AC) is a key signalling enzyme for many GPCRs and catalyses the conversion of ATP to cAMP which, in turn, is a crucial determinant of many biological responses. ß-Adrenoceptor agonists are prescribed as bronchodilators for asthma and chronic obstructive pulmonary disease, and it is commonly assumed that they elicit their actions via AC-dependent production of cAMP. However, empirical evidence in support of this is lacking and the exact mechanism by which these drugs acts remains elusive. This is partly due to the existence of at least 10 different isoforms of AC and the absence of any truly selective pharmacological inhibitors. Here, we have used genetically modified mice and model systems to establish the role of AC isoforms in the airway responses to ß-adrenoceptor agonists. EXPERIMENTAL APPROACH: Receptors mediating responses to ß-adrenoceptor agonists in airway smooth muscle (ASM) and sensory nerve were identified in isolated tissue systems. Expression of mRNA for the AC isoforms in ASM and neurones was determined by qPCR. Functional responses were assessed in AC isoform KO mice and wild-type controls. KEY RESULTS: Airway and vagal tissue expressed mRNA for various isoforms of AC. AC6 was the most prominent isoform. Responses to ß-adrenoceptor agonists in tissues from AC6 KO mice were virtually abolished. CONCLUSIONS AND IMPLICATIONS: AC6 played a critical role in relaxation of ASM to ß1 -adrenoceptor agonists and in modulation of sensory nerves by ß1-3 -adrenoceptor agonists. These results further unravel the signalling pathway of this extensively prescribed class of medicine.

Tiotropium modulates transient receptor potential V1 (TRPV1) in airway sensory nerves: A beneficial off-target effect?

BACKGROUND: Recent studies have suggested that the long-acting muscarinic receptor antagonist tiotropium, a drug widely prescribed for its bronchodilator activity in patients with chronic obstructive pulmonary disease and asthma, improves symptoms and attenuates cough in preclinical and clinical tussive agent challenge studies. The mechanism by which tiotropium modifies tussive responses is not clear, but an inhibition of vagal tone and a consequent reduction in mucus production from submucosal glands and bronchodilation have been proposed. OBJECTIVE: The aim of this study was to investigate whether tiotropium can directly modulate airway sensory nerve activity and thereby the cough reflex. METHODS: We used a conscious cough model in guinea pigs, isolated vagal sensory nerve and isolated airway neuron tissue- and cell-based assays, and in vivo single-fiber recording electrophysiologic techniques. RESULTS: Inhaled tiotropium blocked cough and single C-fiber firing in the guinea pig to the transient receptor potential (TRP) V1 agonist capsaicin, a clinically relevant tussive stimulant. Tiotropium and ipratropium, a structurally similar muscarinic antagonist, inhibited capsaicin responses in isolated guinea pig vagal tissue, but glycopyrrolate and atropine did not. Tiotropium failed to modulate other TRP channel-mediated responses. Complementary data were generated in airway-specific primary ganglion neurons, demonstrating that tiotropium inhibited capsaicin-induced, but not TRPA1-induced, calcium movement and voltage changes. CONCLUSION: For the first time, we have shown that tiotropium inhibits neuronal TRPV1-mediated effects through a mechanism unrelated to its anticholinergic activity. We speculate that some of the clinical benefit associated with taking tiotropium (eg, in symptom control) could be explained through this proposed mechanism of action.

Theophylline inhibits the cough reflex through a novel mechanism of action.

BACKGROUND: Theophylline has been used in the treatment of asthma and chronic obstructive pulmonary disease for more than 80 years. In addition to bronchodilator and anti-inflammatory activity, clinical studies have suggested that theophylline acts as an antitussive agent. Cough is the most frequent reason for consultation with a family doctor, and treatment options are limited. Determining how theophylline inhibits cough might lead to the development of optimized compounds. OBJECTIVE: We sought to investigate the inhibitory activity of theophylline on vagal sensory nerve activity and the cough reflex. METHODS: Using a range of techniques, we investigated the effect of theophylline on human and guinea pig vagal sensory nerve activity in vitro and on the cough reflex in guinea pig challenge models. RESULTS: Theophylline was antitussive in a guinea pig model, inhibited activation of single C-fiber afferents in vivo and depolarization of human and guinea pig vagus in vitro, and inhibited calcium influx in airway-specific neurons in vitro. A sequence of pharmacological studies on the isolated vagus and patch clamp and single-channel inside-out experiments showed that the effect of theophylline was due to an increase in the open probability of calcium-activated potassium channels. Finally, we demonstrated the antitussive activity of theophylline in a cigarette smoke exposure model that exhibited enhanced tussive responses to capsaicin. CONCLUSION: Theophylline inhibits capsaicin-induced cough under both normal and "disease" conditions by decreasing the excitability of sensory nerves through activation of small- and intermediate-conductance calcium-activated potassium channels. These findings could lead to the development of optimized antitussive compounds with a reduced side effect potential.

Tennessee emergency medicine workforce, 2009.

OBJECTIVE: Describe the characteristics of the Tennessee (TN) Emergency Medicine (EM) workforce. METHODS: A cross-sectional mail survey of all non-government emergency departments (EDs) in TN was performed between January and April 2009. Data collected included: number and residency training of physicians, ED volume, employment and type of mid-level providers. Survey datawere compared to recent national EM workforce data. Subgroup analysis of rural EDs using Rural-Urban Commuting Area Code (RUCA) criteria was conducted. RESULTS: We received responses from 50 of the 100 emergency departments surveyed. Roughly half (53 percent) were rural, based on RUCA criteria. Mid-level providers worked with physicians in 31 departments, with physician assistants(PAs) being employed more commonly than nurse practitioners(NPs). Paramedics and emergency medical technicians (EMTs) were employed less frequently. Most EM residency trained physicians in Tennessee are working in EDs with approximately 39,000 annual visits per year or greater. Subspecialty physicians such as neurosurgeons, gastroenterologists and otorhinolaryngologists are generally not available to rural EDs, except by patient transfer, illustrating the marked differences in the work environments. CONCLUSION: While there is clearly a need for more emergency medicine residency training programs in Tennessee, the need to continue to provide advanced training for family medicine residency trained physicians is also clear. Family medicine doctors provide most of the rural emergency medicine in Tennessee.

Harvesting, isolation, and functional assessment of primary vagal ganglia cells.

Airway sensory nerves play an important defensive role in the lungs, being central in mediating protective responses like cough and bronchoconstriction. In some cases, these responses become excessive, hypersensitive, and deleterious. Understanding the normal function of airway nerves and phenotype changes associated with disease will help in developing new therapeutics for treating chronic obstructive pulmonary disease and chronic cough. Guinea pigs, and to a lesser extent ferrets, are commonly employed for studying the cough reflex because they have a cough response similar to humans. While rats and mice do not exhibit a cough response, they do possess sensory nerves that respond to the same range of tussive stimuli as guinea pigs and humans. Described in this unit are protocols for harvesting guinea pig, mouse, and rat sensory nerve cell bodies to assess molecular and functional changes associated with pulmonary disease, and to identify new targets for therapeutic intervention.

Is the inverted surface landing more suitable in evaluating ankle braces and ankle inversion perturbation?

OBJECTIVE: To investigate biomechanical (kinematic) differences between 2 ankle brace testing protocols: landing on an inverted surface (IS) and inversion drop on an inversion platform. DESIGN: Five trials in each of 4 dynamic movement conditions were performed: inversion drop and drop landing from 0.45 m onto an IS without and with an ankle brace. A 7-camera motion analysis system was used to obtain the 3-dimensional kinematics. A 2 × 2 (brace × movement) repeated measures analysis of variance was used to evaluate selected variables for inversion drop and IS landing. SETTING: Research laboratory. PATIENTS: Eleven healthy subjects participated in the study. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Maximum ankle frontal plane and sagittal plane joint angles, range of motion, and maximum angular velocity. RESULTS: The IS landing resulted in significantly earlier maximum inversion, inversion velocities, dorsiflexion range of motion (ROM), contact dorsiflexion velocity, and maximum dorsiflexion velocity compared with the inversion drop. The ankle brace application during the IS landing reduced the contact plantarflexion angle, dorsiflexion ROM and maximum dorsiflexion velocity, and maximum inversion. CONCLUSIONS: The results from this study showed that the IS landing protocol produced significantly earlier maximum inversion angle and velocity and inversion velocities compared with the inversion drop protocol. These results showed that the IS landing is more demanding and should be considered in future investigations of ankle braces and lateral ankle performance/injury mechanisms.

Efficacy of an ankle brace with a subtalar locking system in inversion control in dynamic movements.

STUDY DESIGN: Controlled laboratory study. OBJECTIVES: To examine effectiveness of an ankle brace with a subtalar locking system in restricting ankle inversion during passive and dynamic movements. BACKGROUND: Semirigid ankle braces are considered more effective in restricting ankle inversion than other types of brace, but a semirigid brace with a subtalar locking system may be even more effective. METHODS: Nineteen healthy subjects with no history of major lower extremity injuries were included in the study. Participants performed 5 trials of an ankle inversion drop test and a lateral-cutting movement without wearing a brace and while wearing either the Element (with the subtalar locking system), a Functional ankle brace, or an ASO ankle brace. A 2-way repeated-measures analysis of variance (ANOVA) was used to assess brace differences (P?.05). RESULTS: All 3 braces significantly reduced total passive ankle frontal plane range of motion (ROM), with the Element ankle brace being the most effective. For the inversion drop the results showed significant reductions in peak ankle inversion angle and inversion ROM for all 3 braces compared to the no brace condition; and the peak inversion velocity was also reduced for the Element brace and the Functional brace. In the lateral-cutting movement, a small but significant reduction of the peak inversion angle in early foot contact and the peak eversion velocity at push-off were seen when wearing the Element and the Functional ankle braces compared to the no brace condition. Peak vertical ground reaction force was reduced for the Element brace compared to the ASO brace and the no brace conditions. CONCLUSIONS: These results suggest that the tested ankle braces, especially the Element brace, provided effective restriction of ankle inversion during both passive and dynamic movements.

Evaluation of efficacy and 3D kinematic characteristics of cervical orthoses.

BACKGROUND: Cervical orthoses are often prescribed for both extrication stabilization of trauma patients and a treatment option of injuries to the cervical spine. The objective of this study was to compare effectiveness of two new and two established cervical orthoses in restricting 3D range of motion in the cervical spine. METHODS: Twenty healthy males and females (ten each) participated in the study. Two new cervical collars, C-Breeze and XTW and two established collars, Miami J and Aspen, were examined. A 3-camera Vicon system was used to collect 3D kinematic data. Subjects performed three trials in each of the 15 test conditions wearing no collar and the four cervical collars and performing three different head movements: flexion-extension, left-right lateral flexion, and left-right axial rotation. FINDINGS: The results comparing with the unbraced movements indicated that the Miami J and C-Breeze collars had significantly greater percent reduction on range of motion in flexion than the XTW collar. For both extension and lateral bending, all three collars showed greater percent reduction than the Miami J. The XTW also showed greater reduction than the C-Breeze and Aspen in extension. Finally, the C-Breeze collar showed a significantly more reduction in axial rotation than the Miami J collar. INTERPRETATION: The results suggested that C-Breeze and XTW along with the Miami J and Aspen collars are effective in restricting range of motion in the cervical spine. The two new cervical orthoses also performed either comparably as or better than the two established cervical orthoses.