Elucidating the role of the A2A adenosine receptor in neurodegeneration using neurons derived from Huntington's disease iPSCs.

Huntington's disease (HD) is an autosomal-dominant degenerative disease caused by a cytosine-adenine-guanine trinucleotide expansion in the Huntingtin (htt) gene. The most vulnerable brain areas to mutant HTT-evoked toxicity are the striatum and cortex. In spite of the extensive efforts that have been devoted to the characterization of HD pathogenesis, no disease-modifying therapy for HD is currently available. The A2A adenosine receptor (A2AR) is widely distributed in the brain, with the highest level observed in the striatum. We previously reported that stimulation of the A2AR triggers an anti-apoptotic effect in a rat neuron-like cell line (PC12). Using a transgenic mouse model (R6/2) of HD, we demonstrated that A2AR-selective agonists effectively ameliorate several major symptoms of HD. In the present study, we show that human iPSCs can be successfully induced to differentiate into DARPP32-positive, GABAergic neurons which express the A2AR in a similar manner to striatal medium spiny neurons. When compared with those derived from control subjects (CON-iPSCs), these HD-iPSC-derived neurons exhibited a higher DNA damage response, based on the observed expression of γH2AX and elevated oxidative stress. This is a critical observation, because oxidative damage and abnormal DNA damage/repair have been reported in HD patients. Most importantly, stimulation of the A2AR using selective agonists reduced DNA damage and oxidative stress-induced apoptosis in HD-iPSC-derived neurons through a cAMP/PKA-dependent pathway. These findings support our hypothesis that human neurons derived from diseased iPSCs might serve as an important platform to investigate the beneficial effects and underlying mechanisms of A2AR drugs.

Inhibition of soluble tumor necrosis factor is therapeutic in Huntington's disease.

Neuroinflammation is a common feature of many neurodegenerative diseases, including Huntington's disease (HD). HD is an autosomal dominant genetic disease caused by an expanded CAG repeat in exon 1 of the huntingtin (HTT) gene. Previous studies demonstrated that levels of several proinflammatory cytokines, including tumor necrosis factor (TNF)-α, were higher in the plasma and brain tissues of mice and patients with HD, suggesting that inflammation may contribute to HD progression. To evaluate the pathological role of TNF-α in HD pathogenesis, we blocked TNF-α signaling using a dominant negative inhibitor of soluble TNF-α (XPro1595). XPro1595 effectively suppressed the inflammatory responses of primary astrocytes-enriched culture isolated from a transgenic mouse model (R6/2) and human astrocytes-enriched culture derived from induced pluripotent stem cells (iPSCs) of HD patients evoked by lipopolysaccharide and cytokines, respectively. Moreover, XPro1595 protected the cytokine-induced toxicity of primary R6/2 neurons and human neurons derived from iPSCs of HD patients. To assess the beneficial effect of XPro1595 in vivo, an intracerebroventricular (i.c.v.) infusion was provided with an osmotic minipump. ELISA analyses showed that i.c.v. infusion of XPro1595 decreased elevated levels of TNFα in the cortex and striatum, improved motor function, reduced caspase activation, diminished the amount of mutant HTT aggregates, increased neuronal density and decreased gliosis in brains of R6/2 mice. Moreover, reducing the peripheral inflammatory response by a systemic injection of XPro1595 improved the impaired motor function of R6/2 mice but did not affect caspase activation. Collectively, our findings suggest that an effective and selective anti-inflammatory treatment targeting the abnormal brain inflammatory response is a potential therapeutic strategy for HD.

Aberrant astrocytes impair vascular reactivity in Huntington disease.

OBJECTIVE: Huntington disease (HD) is an inherited neurodegenerative disease caused by the mutant huntingtin gene (mHTT), which harbors expanded CAG repeats. We previously reported that the brain vessel density is higher in mice and patients with HD than in controls. The present study determines whether vascular function is altered in HD and characterizes the underlying mechanism. METHODS: The brain vessel density and vascular reactivity (VR) to carbogen challenge of HD mice were monitored by 3D ΔR2 -mMRA and blood oxygenation level-dependent (BOLD)/flow-sensitive alternating inversion recovery (FAIR) magnetic resonance imaging (MRI), respectively. The amount of vascular endothelial growth factor (VEGF)-A and the pericyte coverage were determined by immunohistochemistry and enzyme-linked immunosorbent assay in human and mouse brain sections, primary mouse astrocytes and pericytes, and human astrocytes derived from induced pluripotent stem cells. RESULTS: Expression of mHTT in astrocytes and neurons is sufficient to increase the brain vessel density in HD mice. BOLD and FAIR MRI revealed gradually impaired VR to carbogen in HD mice. Astrocytes from HD mice and patients contained more VEGF-A, which triggers proliferation of endothelial cells and may be responsible for the augmented neurovascular changes. Moreover, an astrocytic inflammatory response, which reduces the survival of pericytes through an IκB kinase-dependent pathway, mediates the low pericyte coverage of blood vessels in HD brains. INTERPRETATION: Our findings suggest that the inflammation-prone HD astrocytes provide less pericyte coverage by promoting angiogenesis and reducing the number of pericytes and that these changes can explain the inferior VR in HD mice. The resultant impaired VR might hinder cerebral hemodynamics and increase brain atrophy during HD progression.

A critical role of astrocyte-mediated nuclear factor-κB-dependent inflammation in Huntington's disease.

Huntington's disease (HD) is an autosomal disease caused by a CAG repeat expansion in the huntingtin (HTT) gene. The resultant mutant HTT protein (mHTT) forms aggregates in various types of cells, including neurons and glial cells and preferentially affects brain function. We found that two HD mouse models (Hdh(150Q) and R6/2) were more susceptible than wild-type (WT) mice to lipopolysaccharide-evoked systemic inflammation and produced more proinflammatory cytokines in the brain. Such an enhanced inflammatory response in the brain was not observed in N171- 82Q mice that express mHTT only in neurons, but not in glial cells. Thus, HD glia might play an important role in chronic inflammation that accelerates disease progression in HD mice. Intriguingly, enhanced activation of nuclear factor (NF)-κB-p65 (p65), a transcriptional mediator of inflammatory responses, was observed in astrocytes of patients and mice with HD. Results obtained using primary R6/2 astrocytes suggest that these cells exhibited higher IκB kinase (IKK) activity that caused prolongation of NF-κB activation, thus upregulating proinflammatory factors during inflammation. R6/2 astrocytes also produced a more-damaging effect on primary R6/2 neurons than did WT astrocytes during inflammation. Blockage of IKK reduced the neuronal toxicity caused by R6/2 astrocytes and ameliorated several HD symptoms of R6/2 mice (e.g. decreased neuronal density, impaired motor coordination and poor cognitive function). Collectively, our results indicate that enhancement of the p65-mediated inflammatory response in astrocytes contributes to HD pathogenesis. Therapeutic interventions aimed at preventing neuronal inflammation may be an important strategy for treating HD.

Effect of Resistance Exercises on Function and Pain in Fibromyalgia: A Systematic Review and Meta-analysis of Randomized Controlled Trials.

OBJECTIVE: This review aimed to compare the effectiveness of resistance exercise with that of other exercises in functional improvement and pain control in patients with fibromyalgia. DESIGN: PubMed, Embase, Scopus, and Cochrane databases were searched for studies published from their inception until March 2023. The following medical search heading terms were used: "resistance OR strength OR strengthening" AND "fibromyalgia." The analysis was performed using the statistical package Review Manager, version 5.4.1. RESULTS: This study reviewed 11 randomized controlled trials involving 530 patients. In comparison with no intervention, resistance exercise reduced the Fibromyalgia Impact Questionnaire total score, pain score, tender points, and depression and improved physical function. Compared with flexibility exercise, resistance exercise reduced the Fibromyalgia Impact Questionnaire total score. Compared with aerobic exercise, resistance exercise shows similar effects on pain control, reduction of tender points, and improvement of physical function. CONCLUSIONS: Compared with other exercises, resistance exercise demonstrated a more favorable effect on the Fibromyalgia Impact Questionnaire total score, and the effects on pain control, tender points, physical function, and depression were comparable. Thus, resistance exercise exhibits comparable or superior effects when compared with other interventions and more precise research is needed to confirm this conclusion. TO CLAIM CME CREDITS: Complete the self-assessment activity and evaluation online at http://www.physiatry.org/JournalCME. CME OBJECTIVES: Upon completion of this article, the reader should be able to: (1) Appraise the effectiveness and role of resistance exercise as a treatment option for patients with fibromyalgia; (2) Differentiate the comparative effectiveness of resistance exercise in relation to other forms of exercise for patients with fibromyalgia; and (3) Identify demographic factors commonly associated with fibromyalgia. LEVEL: Advanced. ACCREDITATION: The Association of Academic Physiatrists is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.The Association of Academic Physiatrists designates this Journal-based CME activity for a maximum of 1.0 AMA PRA Category 1 Credit(s) ™. Physicians should only claim credit commensurate with the extent of their participation in the activity.

Neurovascular abnormalities in brain disorders: highlights with angiogenesis and magnetic resonance imaging studies.

The coupling between neuronal activity and vascular responses is controlled by the neurovascular unit (NVU), which comprises multiple cell types. Many different types of dysfunction in these cells may impair the proper control of vascular responses by the NVU. Magnetic resonance imaging, which is the most powerful tool available to investigate neurovascular structures or functions, will be discussed in the present article in relation to its applications and discoveries. Because aberrant angiogenesis and vascular remodeling have been increasingly reported as being implicated in brain pathogenesis, this review article will refer to this hallmark event when suitable.

Robotic-assisted hand therapy for improvement of hand function in children with cerebral palsy: a case series study.

BACKGROUND: Most types of robot-assisted training (RT) have been used in Cerebral Palsy (CP) patients only focus on proximal upper extremity. Few of study investigated the effect of distal upper extremity training. CASE REPORT: Pediatric CP patients (N.=7) participated the RT sessions for 6 weeks (12 60-min sessions 2 times a week). Performance was assessed at 3 time points (pretest, posttest, and 1-month follow-up). RT significantly improved in body structure and function domains: FMA-UE scores (P=0.002). On electromyography, significant improvements in the mean brachioradialis muscle amplitude (P=0.015) and electrical agonist-antagonist muscle ratio (P=0.041) in the 1-inch cube-grasping task. The effects were maintained after 1 month. CLINICAL REHABILITATION IMPACT: RT using a Gloreha device which focuses on the distal part of the upper limb benefit on body structure and function, including upper-extremity motor function, brachioradialis muscle recruitment, and coordination in children with cerebral palsy.

Prostaglandins and cyclooxygenases in glial cells during brain inflammation.

Many brain disorders such as Parkinson's disease, Alzheimer's disease, amyotrophic lateral sclerosis (ALS), Huntington, stroke, head trauma, and infection, are associated with inflammation that is involved in neuropathologenesis and hyperalgesis. Microglia and astrocytes act as immune cells in the inflamed brain. Both cell types, but especially microglia, are thought to contribute to the onset of inflammation in many brain diseases by producing deleterious proinflammatory mediators. Prostaglandins (PGs), which are critical mediators of physiologic processes and inflammation, are largely produced by activated microglia and reactive astrocytes during brain inflammation. These compounds are converted from arachnoidic acid (AA) by two isoforms of the cyclooxygenase (COX) enzyme, namely COX-1 and COX-2. In particular, the action of COX-2 and PGs in CNS inflammation has gained much attention recently. PGs have been found to act neuroprotectively by elevating intracellular cAMP levels in neurons. These molecules also function as anti-inflammatory molecules to reduce the production of nitric oxide and proinflammatory cytokines, and to increase the expression of anti-inflammatory cytokines. However, accumulating evidence also shows that COX inhibitors alleviate various types of brain damage via suppressing inflammatory reactions. Accordingly, the roles of two COX enzymes in mediating inflammation and anti-inflammation have recently been debated. We provide here a review of recent findings indicating that the reciprocal interaction of glial cell activation, COX enzymes and PGs mediates neurodegeneration and neuroprotection during brain inflammation. In addition, the mechanism by which PGs mediate signaling is discussed.

Neurovascular abnormalities in humans and mice with Huntington's disease.

Cerebral microvascular aberrations have recently become recognized as a source of pathologies in neurodegenerative disorders, but this concept has not been fully examined with respect to Huntington's disease (HD). A novel in vivo technique, three-dimensional microscopic magnetic resonance angiography (µMRA), allows visualization of the neurovascular system in exquisite detail and provides quantitative structural and functional information. This technique was applied in the present study, in parallel with immunohistological analysis and behavioral assessment, to a well-characterized mouse model of HD (R6/2). Dynamic contrast-enhanced magnetic resonance imaging was used to examine the integrity of the blood-brain barrier (BBB). The µMRA findings revealed an increase in vessel volume fraction and cerebral blood volume in the brains of R6/2 mice at the age of 7weeks when no apparent motor dysfunction was detected. Collagen IV immunostaining disclosed an enhancement in vessel density, but not in vessel size of the microvasculature in the mouse HD brain. This change in neurovasculature worsened with disease progression, with no apparent disruption in the BBB. Most importantly, immunohistological assays of human tissues revealed that the vessel densities in the cortex, caudate/putamen, and substantia nigra were higher in HD patients than in non-HD human subjects. The early onset of such vessel aberrations could be used as a biomarker for the early diagnosis of HD.

Targeting glial cells to elucidate the pathogenesis of Huntington's disease.

Huntington's disease (HD) is a hereditary neurodegenerative disorder caused by expended CAG repeats in the Huntingtin (Htt) gene. The resultant mutant Htt (mHtt) forms aggregates in neurons and causes neuronal dysfunctions. The major characteristic of HD is the selective loss of neurons in the striatum and cortex, which leads to movement disorders, dementia, and eventual death. Expression of mHtt was also found in non-neuronal cells in the brain, suggesting non-cell-autonomous neurotoxicity in HD. As was documented in many different neurodegenerative disorders, elevated inflammatory responses are also reported in HD. To date, effective treatments for this devastating disease remain to be developed. This review focuses on the importance of glial cells and inflammation in HD pathogenesis. Potential anti-inflammatory interventions for HD are also discussed.

TNF-alpha/IFN-gamma-induced iNOS expression increased by prostaglandin E2 in rat primary astrocytes via EP2-evoked cAMP/PKA and intracellular calcium signaling.

Astrocytes, the most abundant glia in the central nervous system (CNS), produce a large amount of prostaglandin E(2) (PGE(2)) in response to proinflammatory mediators after CNS injury. However, it is unclear whether PGE(2) has a regulatory role in astrocytic activity under the inflamed condition. In the present work, we showed that PGE(2) increased inducible nitric oxide synthase (iNOS) production by tumor necrosis factor-alpha and interferon-gamma (T/I) in astrocytes. Pharmacological and RNA interference approaches further indicated the involvement of the receptor EP2 in PGE(2)-induced iNOS upregulation in T/I-treated astrocytes. Quantitative real-time polymerase chain reaction and gel mobility shift assays also demonstrated that PGE(2) increased iNOS transcription through EP2-induced cAMP/protein kinase A (PKA)-dependent pathway. Consistently, the effect of EP2 was significantly attenuated by the PKA inhibitor KT-5720 and partially suppressed by the inhibitor (SB203580) of p38 mitogen-activated protein kinase (p38MAPK), which serves as one of the downstream components of the PKA-dependent pathway. Interestingly, EP2-mediated PKA signaling appeared to increase intracellular Ca(2+) release through inositol triphosphate (IP3) receptor activation, which might in turn stimulate protein kinase C (PKC) activation to promote iNOS production in T/I-primed astrocytes. By analyzing the expression of astrocytic glial fibrillary acidic protein (GFAP), we found that PGE(2) alone only triggered the EP2-induced cAMP/PKA/p38MAPK signaling pathway in astrocytes. Collectively, PGE(2) may enhance T/I-induced astrocytic activation by augmenting iNOS/NO production through EP2-mediated cross-talk between cAMP/PKA and IP3/Ca(2+) signaling pathways.