Effects of Hippotherapy on Health-Related Quality of Life in Caregivers of Children with Cerebral Palsy: A Pilot Quasi-Experimental Study in Japan.

BACKGROUND: Despite accumulating data regarding the beneficial effects of hippotherapy on gait and balance skills in children with cerebral palsy (CP), its effects on caregivers' quality of life (QOL) are limited, presumably due to a lack of reliable and valid measurement tools. This study aims to evaluate the impact of hippotherapy on the health-related QOL of primary caregivers using the Japanese version of the Cerebral Palsy Quality of Life for Children (CP QOL) questionnaire. METHODS: A quasi-experimental design embedded within our existing cohort was utilized. A total of 29 children with CP (range 4-12 years) and their caregivers participated in either a weekly hippotherapy or recreation (usual care) program for 1 year. In addition to gait-related measurements (Gross Motor Function Measure [GMFM]-E) of children, CP QOL-evidenced determinants of the caregivers' health-related QOL and well-being were compared before and after the intervention. RESULTS: In addition to improvements in children's GMFM-E scores, hippotherapy improved CP QOL domains related to participation and physical health, children's emotional well-being, and parents' overall health (p < 0.05). Linear regression analysis showed a positive relationship between the children's GMFM-E scores and their caregivers' health domains in participants who received hippotherapy (r2 = 0.404; p = 0.011). CONCLUSIONS: Hippotherapy has a beneficial effect on the physical and mental well-being and satisfaction of Japanese parents caring for children with CP.

Development and exploration of a Japanese version of the cerebral palsy quality of life for children questionnaire for primary caregivers: a pilot study.

[Purpose] We aimed to translate and validate a Japanese language version of the cerebral palsy quality of life for children questionnaire for primary caregivers and assess the relationship between quality of life of Japanese parents and their children's motor skills. [Participants and Methods] Fifty children (aged 4 to 12 years) and their parents (mothers) were enrolled. The parent-proxy version of the cerebral palsy quality of life for children questionnaire translated to Japanese was administered, and a validation study was performed using Cronbach's α as the key metric. The relationships between the parents' quality of life and children's Gross Motor Function Classification Scale levels were analyzed. [Results] We found that the age of the children and their parents and gender of the children were not significant factors affecting the quality of life domains. Significantly high values of internal consistency were detected among items within each quality of life domain, wherein Cronbach's α was between 0.72 and 0.89. Two quality of life domains (Emotional well-being and Feeling about functioning) were significantly associated with Gross Motor Function Classification Scale levels. [Conclusion] Our data suggest that the original English version of the cerebral palsy quality of life for children questionnaire for primary caregivers was successfully translated to Japanese for use by Japanese-speaking parents caring for their children.

Impact of Long-Term Hippotherapy on the Walking Ability of Children With Cerebral Palsy and Quality of Life of Their Caregivers.

Background: Cerebral palsy (CP) is a permanent motor disorder that occurs at birth or during early infancy. Despite advances in fetal and maternal medicine, the incidence of CP remains high. Hippotherapy has gradually been recognized as an excellent rehabilitation tool for children with CP. However, a scientific basis for how it achieves long-term functional improvements or provides additional benefits to patients' caregivers remains unknown. Objectives: We performed a prospective trial to determine how hippotherapy affects the gross motor and gait functions in children with CP and how it may also impact the quality of life (QOL) of patients' caregivers. Methods: In total, 24 children with CP (11 boys, 13 girls; age: 4-14 years; Gross Motor Function Classification System [GMFCS] II-III) underwent a program (30 min/day, once a week) of hippotherapy or day-care recreation (control) over a 1-year intervention and a 3-month follow-up period. Assessment measures used for the children were gait parameters for a 5-m walk test, Gross Motor Function Measure (GMFM)-66, and GMFM dimension-E (GMFM-E). The QOL of the caregivers was estimated using a brief version of the World Health Organization Quality Of Life (WHOQOL-BREF) self-assessment questionnaire. Results: In addition to better GMFM-66 and GMFM-E scores, hippotherapy was associated with increased cadence, step length, and mean acceleration; stabilized horizontal/vertical displacement of patients; and better relationship between the psychological status and QOL of the caregivers than those seen in the control group (p < 0.05). Additionally, the initially improved children's step length and their caregivers' psychological QOL domain (particularly in the "positive feeling" facet) tended to be preserved up to the 3-month follow-up. Conclusion: These data suggest that compared with common day-care recreational activities, a 1-year program of once-weekly hippotherapy can improve not only the walking ability of children with CP but also the psychological health and QOL of their caregivers. Clinical Trial Registration:: www.umin.ac.jp/ctr/, identifier: UMIN000022986.

Effect of hippotherapy on gait symmetry in children with cerebral palsy: A pilot study.

We aimed to investigate the effect of hippotherapy on gait symmetry in children with cerebral palsy (CP). Twelve children with Gross Motor Function Classification System (GMFCS) levels II-IV received weekly hippotherapy lesson for 1 year. Gait analyses were performed during a 5-m walking test, using a portable, tri-axial accelerometer-based motion recorder. The baseline symmetry index derived from the Lissajous index (LI) figure before hippotherapy was greater than the LI in age-matched normal subjects (P < 0.01). Hippotherapy was associated with a decreased LI (-10.4 ± 4.9%, P = 0.018) and an improved GMFCS score (-0.6 ± 0.7, P = 0.02). These data suggest that hippotherapy has a beneficial effect on symmetry of the trunk movement in children with CP.

Non-invasive three-dimensional power Doppler imaging for the assessment of acute cerebral blood flow alteration in a mouse model of subarachnoid haemorrhage.

We aimed to evaluate the feasibility of a non-invasive method of cerebral blood flow (CBF) measurement using high-frequency power Doppler ultrasound imaging in a mouse model of subarachnoid haemorrhage (SAH). The 3-dimensionally (3D) reconstructed blood flow signals (%vascularity) within the brain volume of the middle cerebral artery territory correlated well with reference parameters, baseline carotid artery blood flow (r2  = 0.52, P < 0.0001) and normalized CBF changes (r2  = 0.74 P < 0.0001). These data suggest that the 3D power Doppler analysis may have the potential for reflecting real-time CBF changes during the acute phase of experimental SAH, which may be applicable to preclinical studies on early brain injury.

Central action of rapamycin on early ischemic injury and related cardiac depression following experimental subarachnoid hemorrhage.

Early brain injury and related cardiac consequences play a key role in the devastating outcomes after subarachnoid hemorrhage (SAH). We reported that rapamycin exerts neuroprotection against cortical hypoxia early after SAH, but its mechanism is poorly understood. This in vivo study aimed to determine the potential role of the transcription factor STAT3 in the rapamycin-mediated neuroprotection in a mouse model of SAH. Forty C57BL/6 N mice were treated with an intracerebroventricular injection of rapamycin or vehicle (control) given after SAH induction by a filament perforation method, with or without STAT3 (Stattic) or ERK (PD98059) inhibitor pretreatment. Cerebral blood flow signals (%vascularity), brain tissue oxygen saturation (SbtO2), and cardiac output (CO) were analyzed using an ultrasound/photoacoustic imaging system. Clinically relevant neurocardiac depression was notable in severe SAH mice. Rapamycin improved %vascularity, SbtO2, and CO on day 1 after SAH onset. The beneficial effects of rapamycin on cerebral blood flow and oxygenation persisted until day 3, resulting in a significant reduction in post-SAH new cerebral infarctions and survival, as well as improved neurological functions, compared to the control group. All of the effects were attenuated by pretreatment with Stattic or PD98059. These data suggest that ERK and JAK/STAT3 pathways play an important role in the neurocardiac protection by rapamycin after SAH. We propose that rapamycin is a novel pharmacological strategy to target STAT3 activation, with a possible crosstalk through the ERK pathway, for the treatment of post-SAH early brain injury.

Impact of serial gait analyses on long-term outcome of hippotherapy in children and adolescents with cerebral palsy.

The aim of this study was to obtain data of gait parameters on predicting long-term outcome of hippotherapy. In 20 participants (4-19 years; GMFCS levels I to III) with cerebral palsy (CP), gait and balance abilities were examined after 10-m walking test using a portable motion recorder. Hippotherapy was associated with increased Gross Motor Function Measure (GMFM)-66 at 1 year from the baseline (P < 0.001). Hippotherapy increased stride length, walking speed, and mean acceleration and decreased horizontal/vertical displacement ratio over time (P < 0.05). Stride length and mean acceleration at 6 weeks predicted the elevation of GMFM-66 score. These data suggest that 1-year outcome of hippotherapy on motor and balance functions can be assessed from the early phase by serial monitoring of the gait parameters.

Noninvasive stroke volume variation using electrical velocimetry for predicting fluid responsiveness in dogs undergoing cardiac surgery.

OBJECTIVE: To evaluate the ability of a noninvasive cardiac output monitoring system with electrical velocimetry (EV) for predicting fluid responsiveness in dogs undergoing cardiac surgery. STUDY DESIGN: Prospective experimental trial. ANIMALS: A total of 30 adult Beagle dogs. METHODS: Stroke volume (SV), stroke volume variation (SVV) and cardiac index were measured using the EV device in sevoflurane-anaesthetized, mechanically ventilated dogs undergoing thoracotomies for experimental creation of right ventricular failure. The dogs were considered fluid responsive if stroke volume (SVI; indexed to body weight), measured using pulmonary artery thermodilution, increased by 10% or more after volume loading (10 mL kg-1). Relationships of SVV, central venous pressure (CVP) and pulmonary artery occlusion pressure (PAOP) with SVI were analysed to estimate fluid responsiveness. RESULTS: Better prediction of fluid responsiveness, with a significant area under the receiver operating characteristic curve, was observed for SVV (0.85±0.07; p=0.0016) in comparison with CVP (0.65±0.11; p=0.17) or PAOP (0.60±0.12; p=0.35), with a cut-off value of 13.5% (84% specificity and 73% sensitivity). CONCLUSIONS AND CLINICAL RELEVANCE: SVV derived from EV is useful for identification of dogs that are likely to respond to fluids, providing valuable information on volume status under cardiothoracic anaesthesia.

Neurocardiac protection with milrinone for restoring acute cerebral hypoperfusion and delayed ischemic injury after experimental subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: Acute cerebral hypoperfusion following subarachnoid hemorrhage (SAH) is highly related to the pathogenesis of delayed cerebral ischemia (DCI), but the therapeutic option is poorly available. This study aimed to clarify the effect of milrinone (MIL) on cerebral blood flow (CBF) and related outcomes after experimental SAH. METHODS: Twenty-seven male C57BL/6 mice were assigned to either sham surgery (SAH-sham; n=6), SAH induced by endovascular perforation (control; n=10), or SAH followed by cardiac support with intravenous MIL (n=11) performed 1.5-h after SAH induction. CBF, neurobehavioral function, occurrence of DCI were assessed by MR-continuous arterial spin labeling, daily neurological score testing, and diffusion- and T2-weighted MR images on days 1 and 3, respectively. RESULTS: Initial global CBF depression was notable in mice of control and MIL groups as compared to the SAH-sham group (P<0.05). MIL raised CBF in a dose-dependent manner (P<0.001), resulted in lower incidence of DCI (P=0.008) and better recovery from neurobehavioral decline than control (P<0.001). The CBF values on day 1 predicted DCI with a cut-off of 42.5ml/100g/min (82% specificity and 83% sensitivity), which was greater in mice treated with MIL than those of control (51.7 versus 37.6ml/100g/min; P<0.001). CONCLUSION: MIL improves post-SAH acute hypoperfusion that can lead to the prevention of DCI and functional worsening, acting as a neurocardiac protective agent against EBI.

Asymptomatic Mild Hyperperfusion for the Prediction of Clinical Outcome in Postoperative Patients After Subarachnoid Hemorrhage.

BACKGROUND Delayed cerebral ischemia (DCI) is one of the main causes of poor outcomes after subarachnoid hemorrhage (SAH). The early identification of DCI by noninvasive imaging modalities would provide valuable information of therapeutic intervention for improving the patient outcomes. We aimed to describe the clinical features of cerebral blood flow (CBF) data obtained from the single-photon emission computed tomography (SPECT) during the risk period for DCI after SAH. MATERIAL AND METHODS Clinical data from 94 SAH patients who underwent surgical clipping of anterior circulation aneurysms were reviewed retrospectively. 99mTc-HMPAO SPECT images were visually and semiquantitatively analyzed on days 7 and 14 after SAH. RESULTS In all cases, the areas of hypoperfusion were found in the middle cerebral artery territories. By contrast, the areas of mild hyperperfusion were always detected on the surgical side, the prevalence which increased from days 7 (n=28; 30%) to 14 (n=48; 51%) without neurological defects. Univariate analysis revealed that the hyperperfusion on day 14 had a significant relationship with functional outcome at 3 months (P=0.04). Multivariate analysis including age, clinical SAH grade, DCI, and hyperperfusion on day 14 showed that DCI (P=0.004; odds ratio [OR], 0.10; 95% confidence interval [CI], 0.02-0.48) and hyperperfusion on day 14 (P=0.002; OR, 2.44; 95% CI, 1.40-4.29) were independently associated with functional outcome at 3 months. CONCLUSIONS Delayed mild hyperperfusion around the surgical site can predict good prognosis after SAH, although it may hinder the CBF diagnosis of focal ischemia attributable to DCI.

Electrical velocimetry for noninvasive cardiac output and stroke volume variation measurements in dogs undergoing cardiovascular surgery.

OBJECTIVE: To compare electrical velocimetry (EV) noninvasive measures of cardiac output (CO) and stroke volume variation (SVV) in dogs undergoing cardiovascular surgery with those obtained with the conventional thermodilution technique using a pulmonary artery catheter. STUDY DESIGN: Prospective experimental trial. ANIMALS: Seven adult Beagle dogs with a median weight of 13.6 kg. METHODS: Simultaneous, coupled cardiac index (CI; CO indexed to body surface area) measurements by EV (CIEV) and the reference pulmonary artery catheter thermodilution method (CIPAC) were obtained in seven sevoflurane-anaesthetized, mechanically ventilated dogs undergoing experimental open-chest cardiovascular surgery for isolated right ventricular failure. Relationships between SVV or central venous pressure (CVP) and stroke volume (SV) were analysed to estimate fluid responsiveness. Haemodynamic data were recorded intraoperatively and before and after fluid challenge. RESULTS: Bland-Altman analysis of 332 matched sets of CI data revealed an overall bias and precision of - 0.22 ± 0.52 L minute-1 m-2 for CIEV and CIPAC (percentage error: 30.4%). Trend analysis showed a concordance of 88% for CIEV. SVV showed a significant positive correlation (r2 = 0.442, p < 0.0001) with SV changes to a volume loading of 200 mL, but CVP did not (r2 = 0.0002, p = 0.94). Better prediction of SV responsiveness (rise of SV index of ≥ 10%) was observed for SVV (0.74 ± 0.09; p = 0.014) with a significant area under the receiver operating characteristic curve in comparison with CVP (0.53 ± 0.98; p = 0.78), with a cut-off value of 14.5% (60% specificity and 83% sensitivity). CONCLUSIONS AND CLINICAL RELEVANCE: In dogs undergoing cardiovascular surgery, EV provided accurate CO measurements compared with CIPAC, although its trending ability was poor. Further, SVV by EV, but not CVP, reliably predicted fluid responsiveness during mechanical ventilation in dogs.

Acute cardiac support with intravenous milrinone promotes recovery from early brain injury in a murine model of severe subarachnoid haemorrhage.

Early brain injury/ischaemia (EBI) is a serious complication early after subarachnoid haemorrhage (SAH) that contributes to development of delayed cerebral ischaemia (DCI). This study aimed to determine the role of inotropic cardiac support using milrinone (MIL) on restoring acute cerebral hypoperfusion attributable to EBI and improving outcomes after experimental SAH. Forty-three male C57BL/6 mice were assigned to either sham surgery (SAH-sham), SAH induced by endovascular perforation plus postconditioning with 2% isoflurane (Control), or SAH plus isoflurane combined with MIL with and without hypoxia-inducible factor inhibitor (HIF-I) pretreatment. Cardiac output (CO) during intravenous MIL infusion (0.25-0.75 µg/kg/min) between 1.5 and 2.5 hours after SAH induction was monitored with Doppler echocardiography. Magnetic resonance imaging (MRI)-continuous arterial spin labelling was used for quantitative cerebral blood flow (CBF) measurements. Neurobehavioral function was assessed daily by neurological score and open field test. DCI was analyzed 3 days later by determining infarction on MRI. Mild reduction of cardiac output (CO) and global cerebral blood flow (CBF) depression were notable early after SAH. MIL increased CO in a dose-dependent manner (P<.001), which was accompanied by improved hypoperfusion, incidence of DCI and functional recovery than Control (P<.05). The neuroprotective effects afforded by MIL or Control were attenuated by hypoxia-inducible factor (HIF) inhibition (P<.05). These results suggest that MIL improves acute hypoperfusion by its inotropic effect, leading to neurobehavioral improvement in mice after severe SAH, in which HIF may be acting as a critical mediator.

Inotropic support against early brain injury improves cerebral hypoperfusion and outcomes in a murine model of subarachnoid hemorrhage.

Early brain injury/ischemia is a recent therapeutic target that contributes to triggering delayed cerebral ischemia (DCI) in the setting of subarachnoid hemorrhage (SAH). This study aimed to determine the role of dobutamine for inotropic cardiac support in improving cerebral blood flow (CBF) and outcomes after experimental SAH, mediated by hypoxia-inducible factor (HIF). Thirty-one mice were subjected to SAH by endovascular perforation, and assigned to either 2% isoflurane postconditioning performed between 1 and 2.5h after SAH induction or concomitant intravenous dobutamine infusion (15µg/kg/min) with or without HIF inhibitor 2-methoxyestradiol (2ME2) (10mg/kg) administered intraperitoneally. Neurobehavioral function was assessed daily by neurological scores and open field testing. DCI was defined 3days later by detecting a new infarction on MRI. Global CBF depression was notable early after SAH, but dobutamine showed significant improvement in CBF, lower incidence of DCI, and better recovery of neuroscores and open field test variables compared with isoflurane postconditioning (P<0.05). CBF over the entire brain on day 1 predicted DCI with a cut-off of 36.5ml/100g/min (80% specificity and 67% sensitivity), with a better area under the curve (0.83 versus 0.75) than the hemispheric CBF measured on the perforated side. The dobutamine-mediated outcomes were attenuated (P<0.05) by 2ME2 pretreatment. The data suggest that cardiac support with dobutamine improves global CBF depression induced by early brain injury, leading to reduced prevalence of DCI and better functional outcomes after experimental SAH, in which HIF may be acting as a critical mediator.

Application of a tri-axial accelerometry-based portable motion recorder for the quantitative assessment of hippotherapy in children and adolescents with cerebral palsy.

[Purpose] This case series aims to evaluate the effects of hippotherapy on gait and balance ability of children and adolescents with cerebral palsy using quantitative parameters for physical activity. [Subjects and Methods] Three patients with gait disability as a sequela of cerebral palsy (one female and two males; age 5, 12, and 25 years old) were recruited. Participants received hippotherapy for 30 min once a week for 2 years. Gait parameters (step rate, step length, gait speed, mean acceleration, and horizontal/vertical displacement ratio) were measured using a portable motion recorder equipped with a tri-axial accelerometer attached to the waist before and after a 10-m walking test. [Results] There was a significant increase in step length between before and after a single hippotherapy session. Over the course of 2 year intervention, there was a significant increase in step rate, gait speed, step length, and mean acceleration and a significant improvement in horizontal/vertical displacement ratio. [Conclusion] The data suggest that quantitative parameters derived from a portable motion recorder can track both immediate and long-term changes in the walking ability of children and adolescents with cerebral palsy undergoing hippotherapy.

Value of Three-Dimensional Maximum Intensity Projection Display to Assist in Magnetic Resonance Imaging (MRI)-Based Grading in a Mouse Model of Subarachnoid Hemorrhage.

BACKGROUND Subarachnoid hemorrhage (SAH) is one of the most devastating cerebrovascular disorders. We report on the diagnostic value of three-dimensional (3-D) maximum intensity projection (MIP) reconstruction of T2*-weighted magnetic resonance images (MRI), processed using graphical user interface-based software, to aid in the accurate grading of endovascular-perforation-induced SAH in a mouse model. MATERIAL AND METHODS A total of 30 mice were subjected to SAH by endovascular perforation; three (10%) were scored as grade 0, six (20%) as grade 1, six (20%) as grade 2, eight (27%) as grade 3, and seven (23%) as grade 4 according to T2*-weighted coronal slices. In comparison, none of mice were scored as grade 0, eight (27%) as grade 1, five (17%) as grade 2, nine (30%) as grade 3, and eight (27%) as grade 4 based on subsequent evaluation using reconstructed 3-D MIP images. RESULTS Mice scored as grade 0 (10%; no visible SAH) on T2*-coronal images were categorized as grades 1 (thin/localized SAH) and 3 (thick/diffuse SAH) according to 3-D MIP images. Grades based on T2* 3-D MIP images were more closely correlated with conventional SAH score (r2=0.59; P<0.0001) and neurological score (r2=0.25; P=0.005) than those based on T2*-coronal slices (r2=0.46; P<0.0001 for conventional score and r2=0.15; P=0.035 for neurological score). CONCLUSIONS These results suggest that 3-D MIP images generated from T2*-weighted MRI data may be useful for the simple and precise grading of SAH severity in mice to overcome the weakness of the current MRI-based SAH grading system.

Therapeutic Potential of Natural Product-Based Oral Nanomedicines for Stroke Prevention.

Cerebral stroke is the leading cause of death and permanent disability in elderly persons. The impaired glucose and oxygen transport to the brain during ischemia causes bioenergetic failure, leading to oxidative stress, inflammation, blood-brain barrier dysfunction, and eventually cell death. However, the development of effective therapies against stroke has been hampered by insufficient oral absorption of pharmaceuticals and subsequent delivery to the brain. Nanotechnology has emerged as a new method of treating cerebral diseases, with the potential to fundamentally change currently available therapeutic approaches using compounds with low bioavailability. This perspective review provides an overview of the therapeutic potential of oral nanomedicines for stroke, focusing on novel natural product-loaded delivery system with potent antioxidant and anti-inflammatory effects.

Isoflurane postconditioning with cardiac support promotes recovery from early brain injury in mice after severe subarachnoid hemorrhage.

AIMS: Neurocardiac dysfunction is a life-threatening systemic consequence of subarachnoid hemorrhage (SAH) that contributes to triggering delayed cerebral ischemia (DCI). This study aimed to determine the impact of dobutamine cardiac support during isoflurane postconditioning on post-SAH DCI. MAIN METHODS: Male C57BL/6 mice were subjected to SAH, SAH plus isoflurane postconditioning, or SAH plus isoflurane postconditioning with dobutamine. Severity of SAH was graded from 1 to 4 (mild, 1-2; severe, 3-4) based on T2*-weighted magnetic resonance imaging (MRI). Cardiac output (CO) measured by transthoracic pulsed wave Doppler-echocardiography was titrated at a supra-normal level with intravenous dobutamine infusion. Neurological function was examined daily by neurological score and Rotarod tests. DCI was analyzed 3days later by determining new infarction on diffusion-weighted MRI. In a separate experiment, mice were pretreated with hypoxia-inducible factor (HIF) inhibitor 2-methoxyestradiol (2ME2). KEY FINDINGS: Clinically relevant CO depression was notable in severe SAH grade mice, in which dobutamine CO management combined with isoflurane postconditioning showed earlier and improved functional recovery than postconditioning with single isoflurane inhalation. Incidence of infarction and volumes on day 3 reduced significantly in this subgroup. All of the effects during preconditioning were attenuated by 2ME2 pretreatment. SIGNIFICANCE: Isoflurane postconditioning under dobutamine cardiac support improves recovery from SAH-induced early brain injury, leading to reduced DCI resultant from severe experimental SAH. These results indicate the importance of neuro-cardiac protection, in which HIF may be acting as a critical mediator, as a promising therapeutic approach to SAH.

Transpulmonary Thermodilution-Based Management of Neurogenic Pulmonary Edema After Subarachnoid Hemorrhage.

Neurogenic pulmonary edema (NPE) is a potentially catastrophic but treatable systemic event after subarachnoid hemorrhage (SAH). The development of NPE most frequently occurs immediately after SAH, and the severity is usually self-limiting. Despite extensive research efforts and a breadth of collective clinical experience, accurate diagnosis of NPE can be difficult, and effective hemodynamic treatment options are limited. Recently, a bedside transpulmonary thermodilution device has been introduced that traces physiological patterns consistent with current theories regarding the mechanism (hydrostatic or permeability PE) of NPE. This article provides an overview of the clinical usefulness of the advanced technique for use in the neurointensive care unit for the diagnosis and management of post-SAH NPE.

CLIC4 mediates and is required for Ca2+-induced keratinocyte differentiation.

Keratinocyte differentiation requires integrating signaling among intracellular ionic changes, kinase cascades, sequential gene expression, cell cycle arrest, and programmed cell death. We now show that Cl(-) intracellular channel 4 (CLIC4) expression is increased in both mouse and human keratinocytes undergoing differentiation induced by Ca(2+), serum and the protein kinase C (PKC)-activator, 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Elevation of CLIC4 is associated with signaling by PKCdelta, and knockdown of CLIC4 protein by antisense or shRNA prevents Ca(2+)-induced keratin 1, keratin 10 and filaggrin expression and cell cycle arrest in differentiating keratinocytes. CLIC4 is cytoplasmic in actively proliferating keratinocytes in vitro, but the cytoplasmic CLIC4 translocates to the nucleus in keratinocytes undergoing growth arrest by differentiation, senescence or transforming growth factor beta (TGFbeta) treatment. Targeting CLIC4 to the nucleus of keratinocytes via adenoviral transduction increases nuclear Cl(-) content and enhances expression of differentiation markers in the absence of elevated Ca(2+). In vivo, CLIC4 is localized to the epidermis in mouse and human skin, where it is predominantly nuclear in quiescent cells. These results suggest that CLIC4 participates in epidermal homeostasis through both alterations in the level of expression and subcellular localization. Nuclear CLIC4, possibly by altering the Cl(-) and pH of the nucleus, contributes to cell cycle arrest and the specific gene expression program associated with keratinocyte terminal differentiation.

Antisense suppression of the chloride intracellular channel family induces apoptosis, enhances tumor necrosis factor {alpha}-induced apoptosis, and inhibits tumor growth.

mtCLIC/CLIC4 is a p53 and tumor necrosis factor alpha (TNFalpha) regulated intracellular chloride channel protein that localizes to cytoplasm and organelles and induces apoptosis when overexpressed in several cell types of mouse and human origin. CLIC4 is elevated during TNFalpha-induced apoptosis in human osteosarcoma cell lines. In contrast, inhibition of NFkappaB results in an increase in TNFalpha-mediated apoptosis with a decrease in CLIC4 protein levels. Cell lines expressing an inducible CLIC4-antisense construct that also reduces the expression of several other chloride intracellular channel (CLIC) family proteins were established in the human osteosarcoma lines SaOS and U2OS cells and a malignant derivative of the mouse squamous papilloma line SP1. Reduction of CLIC family proteins by antisense expression caused apoptosis in these cells. Moreover, CLIC4-antisense induction increased TNFalpha-mediated apoptosis in both the SaOS and U2OS derivative cell lines without altering TNFalpha-induced NFkappaB activity. Reducing CLIC proteins in tumor grafts of SP1 cells expressing a tetracycline-regulated CLIC4-antisense substantially inhibited tumor growth and induced tumor apoptosis. Administration of TNFalpha i.p. modestly enhanced the antitumor effect of CLIC reduction in vivo. These results suggest that CLIC proteins could serve as drug targets for cancer therapy, and reduction of CLIC proteins could enhance the activity of other anticancer drugs.