Knockdown of calpain1 in lumbar motoneurons reduces spasticity after spinal cord injury in adult rats.

Spasticity, affecting ∼75% of patients with spinal cord injury (SCI), leads to hyperreflexia, muscle spasms, and cocontractions of antagonist muscles, greatly affecting their quality of life. Spasticity primarily stems from the hyperexcitability of motoneurons below the lesion, driven by an upregulation of the persistent sodium current and a downregulation of chloride extrusion. This imbalance results from the post-SCI activation of calpain1, which cleaves Nav1.6 channels and KCC2 cotransporters. Our study was focused on mitigating spasticity by specifically targeting calpain1 in spinal motoneurons. We successfully transduced lumbar motoneurons in adult rats with SCI using intrathecal administration of adeno-associated virus vector serotype 6, carrying a shRNA sequence against calpain1. This approach significantly reduced calpain1 expression in transduced motoneurons, leading to a noticeable decrease in spasticity symptoms, including hyperreflexia, muscle spasms, and cocontractions in hindlimb muscles, which are particularly evident in the second month post-SCI. In addition, this decrease, which prevented the escalation of spasticity to a severe grade, paralleled the restoration of KCC2 levels in transduced motoneurons, suggesting a reduced proteolytic activity of calpain1. These findings demonstrate that inhibiting calpain1 in motoneurons is a promising strategy for alleviating spasticity in SCI patients.

Cortical Parvalbumin-Positive Interneuron Development and Function Are Altered in the APC Conditional Knockout Mouse Model of Infantile and Epileptic Spasms Syndrome.

Infantile and epileptic spasms syndrome (IESS) is a childhood epilepsy syndrome characterized by infantile or late-onset spasms, abnormal neonatal EEG, and epilepsy. Few treatments exist for IESS, clinical outcomes are poor, and the molecular and circuit-level etiologies of IESS are not well understood. Multiple human IESS risk genes are linked to Wnt/ß-catenin signaling, a pathway that controls developmental transcriptional programs and promotes glutamatergic excitation via ß-catenin's role as a synaptic scaffold. We previously showed that deleting adenomatous polyposis coli (APC), a component of the ß-catenin destruction complex, in excitatory neurons (APC cKO mice, APCfl/fl x CaMKIIαCre) increased ß-catenin levels in developing glutamatergic neurons and led to infantile behavioral spasms, abnormal neonatal EEG, and adult epilepsy. Here, we tested the hypothesis that the development of GABAergic interneurons (INs) is disrupted in APC cKO male and female mice. IN dysfunction is implicated in human IESS, is a feature of other rodent models of IESS, and may contribute to the manifestation of spasms and seizures. We found that parvalbumin-positive INs (PV+ INs), an important source of cortical inhibition, were decreased in number, underwent disproportionate developmental apoptosis, and had altered dendrite morphology at P9, the peak of behavioral spasms. PV+ INs received excessive excitatory input, and their intrinsic ability to fire action potentials was reduced at all time points examined (P9, P14, P60). Subsequently, GABAergic transmission onto pyramidal neurons was uniquely altered in the somatosensory cortex of APC cKO mice at all ages, with both decreased IPSC input at P14 and enhanced IPSC input at P9 and P60. These results indicate that inhibitory circuit dysfunction occurs in APC cKOs and, along with known changes in excitation, may contribute to IESS-related phenotypes.SIGNIFICANCE STATEMENT Infantile and epileptic spasms syndrome (IESS) is a devastating epilepsy with limited treatment options and poor clinical outcomes. The molecular, cellular, and circuit disruptions that cause infantile spasms and seizures are largely unknown, but inhibitory GABAergic interneuron dysfunction has been implicated in rodent models of IESS and may contribute to human IESS. Here, we use a rodent model of IESS, the APC cKO mouse, in which ß-catenin signaling is increased in excitatory neurons. This results in altered parvalbumin-positive GABAergic interneuron development and GABAergic synaptic dysfunction throughout life, showing that pathology arising in excitatory neurons can initiate long-term interneuron dysfunction. Our findings further implicate GABAergic dysfunction in IESS, even when pathology is initiated in other neuronal types.

Effects of Pulsed Electric Fields on the Coronary Arteries in Swine.

BACKGROUND: Previous animal studies have shown no significant vascular injury from pulsed electrical field (PEF) ablation. We sought to assess the effect of PEF on swine coronary arteries. METHODS: We performed intracoronary and epicardial (near the coronary artery) PEF ablations in swine pretreated with dual antiplatelet and antiarrhythmic therapy. Intracoronary PEF was delivered using MapiT catheters (Biotronik, Berlin), whereas epicardial PEF was delivered using EPT catheters (Boston Scientific, MA). PEF pulse duration was microseconds (Nanoknife 3.0, Angio Dynamics, NY) or nanoseconds (CellFX, Pulse Biosciences, CA). RESULTS: We performed 39 intracoronary ablations in 10 swine and 20 epicardial-pericoronary ablations in 4 separate swine. Intracoronary PEF was delivered at higher energy compared with epicardial PEF (46 [interquartile range, IQR 20-85] J versus 10 [IQR 10-11] J, P < 0.01). Reversible coronary spasm occurred in 49% intracoronary ablations and 45% epicardial ablations (P=0.80). At the end study, fixed coronary stenosis was demonstrated in 44% intracoronary ablations (80% for microsecond PEF and 18% for nanosecond PEF) and 0% epicardial ablations. Visible hemorrhagic and/or fibrotic myocardial lesions were observed at necropsy with similar frequency between intracoronary and epicardial PEF (45% versus 50%, P=0.70). Nanosecond PEF (49 ablations in 11 swine), when compared with microsecond PEF (10 intracoronary ablations in 3 swine), resulted in lower energy delivery (21 [IQR 10-46] J versus 129 [IQR 24-143] J, P=0.03) and less incidence of fixed coronary stenosis (18% versus 80%, P=0.04). CONCLUSIONS: In the swine model, intracoronary PEF resulted both in significant coronary spasm and fixed coronary stenosis. Epicardial PEF, delivered at lower energy, resulted in reversible spasm but no fixed coronary stenosis.

Layered Plaque in Organic Lesions in Patients With Coronary Artery Spasm.

Background Coronary artery spasm plays a vital role in the pathogenesis of coronary plaques. We sought to investigate the plaque characteristics of co-existing organic lesions in patients with coronary artery spasm in comparison to those without coronary artery spasm by intracoronary optical coherence tomography (OCT). Methods and Results We included 39 patients who presented with a symptom suspected of coronary spastic angina and had an organic lesion, defined as ≥plaque burden of 50% assessed by OCT. Coronary artery spasm was diagnosed by positive acetylcholine provocation test, or by spontaneous spasm detected during coronary angiography. A total of 51 vessels with an organic lesion were identified. Of these, coronary artery spasm was observed in 30 vessels (spasm), while not in 21 vessels (non-spasm). Organic lesions in the spasm vessels, compared with those in the non-spasm vessels, had a higher prevalence of layered plaque (93% versus 38%, P<0.001), macrophages (80% versus 43%, P=0.016), and intraplaque microchannels (73% versus 24%, P<0.001), and lower prevalence of macrocalcification (23% versus 62%, P=0.009) as assessed by OCT. Conclusions Layered plaque, macrophages, and intraplaque microchannels, were frequently observed in organic lesions in patients with coronary artery spasm. These findings suggest that coronary artery spasm induces local thrombus formation as well as active inflammatory response, therefore increasing the risk of rapid plaque progression and ischemic events in patients with coronary artery spasm.

Apolipoprotein (a)/Lipoprotein(a)-Induced Oxidative-Inflammatory α7-nAChR/p38 MAPK/IL-6/RhoA-GTP Signaling Axis and M1 Macrophage Polarization Modulate Inflammation-Associated Development of Coronary Artery Spasm.

OBJECTIVE: Apolipoprotein (a)/lipoprotein(a) (Lp(a)), a major carrier of oxidized phospholipids, and α7-nicotinic acetylcholine receptor (α7-nAChR) may play an important role in the development of coronary artery spasm (CAS). In CAS, the association between Lp(a) and the α7-nAChR-modulated inflammatory macrophage polarization and activation and smooth muscle cell dysfunction remains unknown. METHODS: We investigated the relevance of Lp(a)/α7-nAChR signaling in patient monocyte-derived macrophages and human coronary artery smooth muscle cells (HCASMCs) using expression profile correlation analyses, fluorescence-assisted cell sorting flow cytometry, immunoblotting, quantitative real-time polymerase chain reaction, and clinicopathological analyses. RESULTS: There are increased serum Lp(a) levels (3.98-fold, p = 0.011) and macrophage population (3.30-fold, p = 0.013) in patients with CAS compared with patients without CAS. Serum Lp(a) level was positively correlated with high-sensitivity C-reactive protein (r 2 = 0.48, p < 0.01), IL-6 (r 2 = 0.38, p = 0.03), and α7-nAChR (r 2 = 0.45, p < 0.01) in patients with CAS, but not in patients without CAS. Compared with untreated or low-density lipoprotein- (LDL-) treated macrophages, Lp(a)-treated macrophages exhibited markedly enhanced α7-nAChR mRNA expression (p < 0.01) and activity (p < 0.01), in vitro and ex vivo. Lp(a) but not LDL preferentially induced CD80+ macrophage (M1) polarization and reduced the inducible nitric oxide synthase expression and the subsequent NO production. While shRNA-mediated loss of α7-nAChR function reduced the Lp(a)-induced CD80+ macrophage pool, both shRNA and anti-IL-6 receptor tocilizumab suppressed Lp(a)-upregulated α7-nAChR, p-p38 MAPK, IL-6, and RhoA-GTP protein expression levels in cultures of patient monocyte-derived macrophages and HCASMCs. CONCLUSIONS: Elevated Lp(a) levels upregulate α7-nAChR/IL-6/p38 MAPK signaling in macrophages of CAS patients and HCASMC, suggesting that Lp(a)-triggered inflammation mediates CAS through α7-nAChR/p38 MAPK/IL-6/RhoA-GTP signaling induction, macrophage M1 polarization, and HCASMC activation.

Myocardial Infarction in Non-obstructive Coronary Arteries (MINOCA) in the Perioperative Period can Epinephrine be Responsible?

Ephedrine, metaraminol, epinephrine and maneuvers like carotid sinus stimulation used during intraoperative period have been postulated to cause temporary spasm of the coronary vessels leading to decrease supply to the myocardium and precipitating myocardial infraction in non-obstructive coronary arteries (MINOCA). As an anaesthesiologists, we should be aware that even a dose as small as 25 mcg epinephrine infiltrated along with local anaesthetic in the subcutaneous plane may be responsible for coronary vessel spasm and thus myocardial infraction in nonobstructive coronary arteries. We report a case of 45 years old female with papillary carcinoma of thyroid who developed features of non-ST elevation myocardial infarction 5 minutes after the subcutaneous infiltration of 5 ml of 2% Xylocaine with 1:200000 Epinephrine. Patient was managed for acute Myocardial Infarction. Coronary angiogram done the next day revealed normal coronary arteries, hence the diagnosis Myocardial infraction in non-obstructive coronary arteries was made.

Adenocarcinoma arising in the multiple heterotopic submucosal glands of the intestine in a Satoyoshi syndrome patient: A case report.

Satoyoshi syndrome is a rare multisystemic disorder of unknown etiology characterized by progressive muscle spasms, alopecia and diarrhea. Multiple protruding lesions with cystic glands, namely gastroenterocolitis cystica polyposa, manifest in the gastrointestinal tract. Since the first report of these lesions in 1977, which was unique to Satoyoshi syndrome, few studies have focused on their role, and the associated clinicopathological features are not well understood. Here, we report a 64-year-old Japanese woman with Satoyoshi syndrome who presented with multiple polypoid lesions in the stomach, duodenum, jejunum, ileum and colon. Histologically, the polypoid lesions in the intestine comprised multiple heterotopic submucosal glands containing cystically dilated glands and smooth muscle fibers in the lamina propria mucosa and/or submucosa. Additionally, we observed stromal changes, such as fibrosis, discontinuous and thinning muscularis mucosae, and diffuse neural fiber proliferation in the entire intestinal tract. Furthermore, multiple foci of adenocarcinomas were identified within several heterotopic submucosal glands. We hypothesized that multiple heterotopic submucosal glands in the present case corresponded to previously reported gastroenterocolitis cystica polyposa, suggesting that these lesions are essential in the histopathology and are a unique manifestation of Satoyoshi syndrome.

Regulatory role of hippocampal PI3K and mTOR signaling pathway in NMDA-induced infant spasm rats.

Objectives: To explore the role of mTOR signaling pathway in modulating epileptogenesis in an N-methyl-D-aspartic acid (NMDA)-induced infant spasm (IS) rat model. Methods: After inducing IS successfully, the phosphorylation status of PI3K, Akt, mTOR and S6K of brain and hippocampus tissues was assessed using western blot and immunochemistry analysis, respectively. The possible mechanism of mTOR signaling pathway was evaluated by the, inhibitors for mTOR and PI3K, rapamycin and wortmannin, respectively. The inhibitors were injected into the intraperitoneal space of the rats to examine the effects of PI3K and mTOR in IS rat model. Results: The phosphorylated levels of mTOR and PI3K in hippocampus increased significantly (P < 0.05) 7 days after IS induction in rats. After administration of wortmannin, the phosphorylated levels of PI3K and mTOR decreased. However, only the phosphorylated level of mTOR decreased obviously after rapamycin administration. No obvious neurogenesis was found after IS induction. Discussion: Results of the present study suggest that hippocampal PI3K may be another potential target for IS treatment.

Epileptic spasm and other forms of epilepsy in presumed perinatal arterial ischemic stroke in Turkey after more than 10 years follow-up: A single centre study.

PURPOSE: To identify the frequency of epilepsy and whether the association of epilepsy with clinical and neuroimaging findings in children with presumed perinatal arterial ischemic stroke (PPAIS). METHODS: We performed a retrospective analysis of 37 children with PPAIS followed-up at a tertiary referral center between January 1, 2000, and October 31, 2016. Clinical data including demographic features, age at onset of symptoms and seizures, initial clinical presentation, epilepsy features, used antiepileptic drugs, and thrombophilia screening results were abstracted from medical records. Brain magnetic resonance imaging scans were assessed for infarct laterality, location and affected brain regions. RESULTS: The median age of the patients was 12 years (range 2-17.9 years) at last assessment. The initial symptom of PPAIS was early hand preference in 33 children (89%) and seizure in 4 children (11%). A total of 20 children (54%) developed epilepsy at a median age of 0.9 years. There were two peaks of epilepsy onset in infancy and adolescence. Fifteen children (41%) had focal epilepsy and 5 children (14%) had epileptic spasms. Twelve out of 20 children (60%) with epilepsy had drug resistant epilepsy. Cortical involvement was a statistically significant predictor of epilepsy (p = 0.021, relative risk 4.4, 95% confidence interval 0.7-27.7). CONCLUSION: More than half of the children with PPAIS suffered from epilepsy during childhood, of whom developed drug resistant epilepsy in majority. Children with cortical lesion may have a higher risk to develop epilepsy.

Predeterminative role of Onuf's nucleus ischemia on mesenteric artery vasospasm in spinal subarachnoid hemorrhage: A preliminary experimental study.

BACKGROUND: Although posttraumatic mesenteric artery ischemia is attributed to various etiologies, sacral parasympathetic network/mesenteric artery relations have not been studied so far. The primary objective of this study is to elucidate whether there is a relationship between Onuf's nucleus ischemia and mesenteric artery vasospasm following subarachnoid hemorrhage (SAH). METHODS: This study was conducted on 22 rabbits. The animals were grouped as follows: 5 of animals control, 5 SHAM which saline was given, and 12 animals study group that was homologous blood injected into the spinal subarachnoid space at the Li level. Neurodegeneration in Onuf's nucleus, axonal degeneration of S2 roots, and mesenteric arteries vasospasm indexes (VSI; Wall surface/Lumen surface), brachias of mesentery arteries in various tissues and ischemic mucosal changes of intestines of all animals were determined histopathologically. Important degenerative changes were detected in axons in S2 roots and Onuf's nucleus in severe mesenteric artery vasospasm observed. RESULTS: The mean degenerated neuron density of Onuf's nucleus (n/mm3), degenerated axon density in S2 roots (n/mm2), and VSI values of mesenteric arteries of control, SHAM, and study groups were estimated as 5.00 ± 1.58, 4.00 ± 1.58, 1.76 ± 0.13; 18.29 ± 4.31, 11.00 ± 2.24, 2.23 ± 0.20; and 135.21 ± 30.75, 117.33 ± 22.11, 2.81 ± 0.44, respectively. Statistical analyses between the VSI values, mucosal ischemic changes degenerated neurons in Onuf's nucleus, and axons in S2 levels were meaningful (p < 0.005). CONCLUSION: We interestingly noticed that Onuf's nucleus-S2 roots complex degeneration plays an important role in mesenteric artery vasospasm and the development of intestinal ischemic mucosal changes following SAH which has not been extensively mentioned in the literature.

Opisthotonos and unilateral internal hydrocephalus associated with aberrant migration of Serratospiculum sp. or Serratospiculoides sp. in a prairie falcon.

A juvenile, wild-caught prairie falcon ( Falco mexicanus) kept for falconry was presented to a veterinary hospital for intermittent opisthotonos and torticollis. Clinical examination, complete blood count, serum biochemistry panel, and fecal analysis were unremarkable. Clinical signs did not resolve, and the bird was euthanized 6 mo after the appearance of clinical signs. Autopsy revealed a mild, unilateral hydrocephalus and nematodes within the thoracic air sac. Histopathology demonstrated mild, unilateral hydrocephalus; scattered glial nodules; meningeal nematode sections; and meningeal and intraventricular embryonated eggs. Morphology and molecular characterization were consistent with the air sac nematode Serratospiculum or Serratospiculoides spp. Air sac nematode infection can be associated with air sacculitis or pneumonia in falcons. Aberrant migration of air sac filariid nematodes Serratospiculum or Serratospiculoides spp. into the nervous system resulting in clinical disease is rare, but should be included in the differential diagnosis of neurologic diseases in falcons.

Prolotherapy for the Thoracolumbar Myofascial System.

Prolotherapy has focused on entheses as a key source of chronic low back pain, even without clear diagnosis of enthesopathy. Treatment has traditionally been guided by anatomic knowledge and careful palpation. This article integrates ultrasonographic diagnosis of fascial injury with examination findings taught in traditional prolotherapy technique. Thoracolumbar fascial anatomy and biotensegrity theory are used to explain patient presentation and response to treatment at these pathologic findings. Detailed case reports provide proof of concept for the 60-year history of prolotherapy in the treatment of chronic low back pain.

Brain tumors and epileptic spasms: Natural history and outcomes.

While brain tumors are a frequent cause of seizures, they rarely cause epileptic spasms (ES). The objective of this study was to investigate features of tumor-associated ES. We conducted a retrospective review of patients with ES and a brain tumor. Demographics; pathologic, radiologic, and EEG data; treatment response; and long-term outcome were collected. Twenty four patients were identified; 11 met inclusion criteria. Epileptic spasm (ES) onset occurred prior to tumor diagnosis in seven patients (63%), and after tumor resection in 4 patients (36%). Spasms and ictal EEG often had focal features (45%). Gross total tumor resection resulted in ES freedom in 3/7 patients. There was poor response to first-line therapy (ACTH/vigabatrin; 1/5 with ES freedom). Low grade tumors predominated (8/11) with dual pathology (associated cortical malformation) in 2 patients. All tumors involved cortex; half involved subcortical regions and/or brainstem. Ten patients developed other seizure types; eight experienced refractory epilepsy, and nine had a Modified Rankin Scale of >3. In summary, EEG in tumor-associated ES often has focal features of either the semiology or EEG. Complete tumor resection yielded ES freedom in only a subset of patients. Most patients developed refractory epilepsy and adverse developmental outcomes.

Leigh-like neuroimaging features associated with new biallelic mutations in OPA1.

Behr syndrome is characterized by the association of early onset optic atrophy, cerebellar ataxia, pyramidal signs, peripheral neuropathy and mental retardation. Recently, some cases were reported to be caused by biallelic mutations in OPA1. We describe an 11-year-old girl (Pt1) and a 7-year-old boy (Pt2) with cognitive delay, ataxic gait and clinical signs suggestive of a peripheral neuropathy, with onset in early infancy. In Pt1 ocular fundus examination revealed optic disk pallor whereas Pt2 exhibited severe optic atrophy. In both children neuroimaging detected a progressive cerebellar involvement accompanied by basal ganglia hyperintensities and pathological peak levels of lactate. In both patients, muscle biopsy showed diffuse reduction of cytochrome c oxidase stain, some atrophic fibers and type II fiber grouping. Using a targeted resequencing panel in next generation sequencing, we identified the homozygous c.1180G>A/p.Ala394Thr mutation in Pt1 and the c.2779-2A>C mutation in compound heterozygosity with the c.2809C>T/p.Arg937Cys mutation in Pt2. All variants were novel and segregated in the healthy parents. Expression of OPA1 protein was significantly reduced in muscle tissues of both patients by Western blotting. We also observed in patients' fibroblasts a higher proportion of fragmented and intermediate mitochondria upon galactose treatment compared to controls, as already seen in other patients harboring mutations in OPA1. The presence of Leigh-like neuroimaging features is a novel finding in Behr syndrome and further adds to the complex genotype-phenotype correlations in OPA1-associated disorders.

Generation of optic atrophy 1 patient-derived induced pluripotent stem cells (iPS-OPA1-BEHR) for disease modeling of complex optic atrophy syndromes (Behr syndrome).

Human skin fibroblasts were isolated from a 48-year-old patient carrying compound heterozygous mutations (c.610+364G>A and c.1311A>G) in OPA1, responsible for early onset optic atrophy complicated by ataxia and pyramidal signs (Behr syndrome; OMIM #210000). Fibroblasts were reprogrammed using episomal plasmids carrying hOCT4, hSOX2, hKLF4, hL-MYC and hLIN28. The generated transgene-free line iPS-OPA1-BEHR showed no additional genomic aberrations, maintained the disease-relevant mutations, expressed important pluripotency markers and was capable to differentiate into cells of all three germ layers in vitro. The generated iPS-OPA1-BEHR line might be a useful platform to study the pathomechanism of early onset complicated optic atrophy syndromes.

Accommodative spasm might influence surgical planning and outcomes in acute acquired distance esotropia in myopia.

INTRODUCTION: Acute acquired distance esotropia (AADE) is a poorly understood moderate-angle strabismus, affecting young adult myopes and determining bothersome diplopia. Symptoms can be intermittent in the early stages, becoming constant in long-lasting disease. Symptomatic therapy includes prism correction, while surgery is the only curative treatment. However, the latter is affected by high rate of symptoms recurrence with the frequent need for reoperation. HYPOTHESIS: We hypothesize that AADE could be caused by the increase of the accommodative demand, often secondary to a myopic overcorrection. This condition could determine an increase in induced hyperopia at near, dominated by an excess of accommodation and therefore of convergence. The latter cannot be relaxed at distance and diplopia develops. We speculate that early-stage AADE could be successfully treated by cycloplegic eye drops slowly tapered within three months. On the other hand, surgery remains the only option in long-lasting AADE. In these cases, we propose a new pre-operative assessment of esotropia by asking the patient to fix alternatively a stimulus at near and at distance in order to stimulate the accommodative convergence. This technique allows to unmask the total amount of the angle of deviation and to plan a wider bilateral medial rectus muscle recession avoiding long-term residual esotropia. DISCUSSION: Currently, AADE curative therapy is surgical regardless of onset time but it is usually affected by poor outcomes. If our hypothesis was to be confirmed, pharmacological treatment could solve early-stage AADE, avoiding any surgery. Furthermore, a wide bilateral medial rectus muscle recession, quantified on the basis of the above mentioned test for measuring the total amount of the strabismus angle, could improve outcomes eliminating the need for reoperation in long-lasting AADE.

Spinal Cord Hamartomatous Myelodysplasia in 2 Horses With Clinical Neurologic Deficits.

Two horses euthanized for neurologic deficits were diagnosed with hamartomatous myelodysplasia of the spinal cord. One was a 5-week-old Holsteiner colt exhibiting spasms of muscle rigidity in the extensor muscles of the limbs and epaxial muscles, and the other was a 3-year-old Thoroughbred colt exhibiting progressive ataxia and hypermetria in the pelvic limbs. Each had focal disorganization of the white and gray matter of the spinal cord forming a mass interspersed with neurons, glial cells, and disoriented axon bundles. In the Holsteiner colt, the mass was at the level of C5 and included islands of meningeal tissue contiguous with the leptomeninges. The mass occluded the central canal forming hydromyelia cranial to the occlusion. In the Thoroughbred colt, the mass was at the level of L1 on the dorsal periphery of the spinal cord and did not involve the central canal.

Angiotensin-(1-7) Attenuates Skeletal Muscle Fibrosis and Stiffening in a Mouse Model of Extremity Sarcoma Radiation Therapy.

BACKGROUND: Radiation-induced fibrosis (RIF) of musculoskeletal tissue is a common complication of radiation therapy for extremity soft-tissue sarcoma, with no standardized strategy for prevention and treatment. Angiotensin-(1-7) (Ang-[1-7]), a well-tolerated endogenous heptapeptide hormone with antitumor and antifibrotic properties, was tested as a radioprotectant for RIF and stiffening of irradiated muscles. METHODS: Male CD-1 mice were randomized to one of three treatment groups: control, simulated sarcoma radiation therapy to the gastrocnemius and soleus muscles, or radiation therapy along with continuous Ang-(1-7) delivery initiated three days before radiation therapy. The biologically equivalent dose of radiation (∼100.3 Gy) absorbed by normal musculature during the course of radiation therapy for extremity sarcoma was delivered by means of four dose fractions of 7.3 Gy over two weeks. Fibrosis (n = 5 per group) and mechanical properties (n = 4 to 6 per group) of the muscles were measured at six weeks and four months after radiation therapy, and the intramuscular concentration of the profibrotic cytokines transforming growth factor-beta (TGF-ß) and connective tissue growth factor (CTGF) (n = 8 to 10 per group) were measured at six weeks. RESULTS: Interstitial (p < 0.01) and perivascular (p < 0.05) fibrosis increased significantly in the muscles treated with radiation therapy alone versus the nonirradiated controls at both six weeks (interstitial, +89%; perivascular, +112%) and four months (interstitial, +154%; perivascular, +88%). The muscles treated with radiation alone also exhibited increased tension (p < 0.01) versus nonirradiated controls at both six weeks (+779%) and four months (+1761%) when placed under 5% strain, and at four months (+1390%; p < 0.001) under 10% strain. At four months, muscle stiffness had increased in the mice treated with radiation therapy alone (+90%; p = 0.002) compared with nonirradiated controls. TGF-ß production was also greater in this group at six weeks (+37%; p = 0.06) versus control. Ang-(1-7) administration prevented RIF and stiffening, with no differences observed for any other outcome between those receiving radiation therapy with Ang-(1-7) and the nonirradiated controls. Likewise, Ang-(1-7) mitigated the increase in TGF-ß and CTGF concentration from radiation therapy. CONCLUSIONS: Ang-(1-7) attenuated RIF, stiffening, and production of profibrotic cytokines that were elevated in mouse skeletal muscles after simulated radiation therapy for extremity sarcoma. CLINICAL RELEVANCE: Ang-(1-7) may serve as a potential therapy for the prevention of RIF in patients who require radiation therapy as adjuvant treatment for soft-tissue sarcoma.