Non-invasive peripheral focused ultrasound neuromodulation of the celiac plexus ameliorates symptoms in a rat model of inflammatory bowel disease.

NEW FINDINGS: What is the central question of this study? Does peripheral non-invasive focused ultrasound targeted to the celiac plexus improve inflammatory bowel disease? What is the main finding and its importance? Peripheral non-invasive focused ultrasound targeted to the celiac plexus in a rat model of ulcerative colitis improved stool consistency and reduced stool bloodiness, which coincided with a longer and healthier colon than in animals without focused ultrasound treatment. The findings suggest that this novel neuromodulatory technology could serve as a plausible therapeutic approach for improving symptoms of inflammatory bowel disease. ABSTRACT: Individuals suffering from inflammatory bowel disease (IBD) experience significantly diminished quality of life. Here, we aim to stimulate the celiac plexus with non-invasive peripheral focused ultrasound (FUS) to modulate the enteric cholinergic anti-inflammatory pathway. This approach may have clinical utility as an efficacious IBD treatment given the non-invasive and targeted nature of this therapy. We employed the dextran sodium sulfate (DSS) model of colitis, administering lower (5%) and higher (7%) doses to rats in drinking water. FUS on the celiac plexus administered twice a day for 12 consecutive days to rats with severe IBD improved stool consistency scores from 2.2 ± 1 to 1.0 ± 0.0 with peak efficacy on day 5 and maximum reduction in gross bleeding scores from 1.8 ± 0.8 to 0.8 ± 0.8 on day 6. Similar improvements were seen in animals in the low dose DSS group, who received FUS only once daily for 12 days. Moreover, animals in the high dose DSS group receiving FUS twice daily maintained colon length (17.7 ± 2.5 cm), while rats drinking DSS without FUS exhibited marked damage and shortening of the colon (13.8 ± 0.6 cm) as expected. Inflammatory cytokines such as interleukin (IL)-1ß, IL-6, IL-17, tumour necrosis factor-α and interferon-γ were reduced with DSS but coincided with control levels after FUS, which is plausibly due to a loss of colon crypts in the former and healthier crypts in the latter. Lastly, overall, these results suggest non-invasive FUS of peripheral ganglion can deliver precision therapy to improve IBD symptomology.

Suramin-Induced Neurotoxicity: Preclinical Models and Neuroprotective Strategies.

Suramin is a trypan blue analogon originally developed to treat protozoan infections, which was found to have diverse antitumor effects. One of the most severe side effects in clinical trials was the development of a peripheral sensory-motor polyneuropathy. In this study, we aimed to investigate suramin-induced neuropathy with a focus on calcium (Ca2+) homeostasis as a potential pathomechanism. Adult C57Bl/6 mice treated with a single injection of 250 mg/kg bodyweight suramin developed locomotor and sensory deficits, which were confirmed by electrophysiological measurements showing a predominantly sensory axonal-demyelinating polyneuropathy. In a next step, we used cultured dorsal root ganglia neurons (DRGN) as an in vitro cell model to further investigate underlying pathomechanisms. Cell viability of DRGN was significantly decreased after 24-hour suramin treatment with a calculated IC50 of 283 µM. We detected a suramin-induced Ca2+ influx into DRGN from the extracellular space, which could be reduced with the voltage-gated calcium channel (VGCC) inhibitor nimodipine. Co-incubation of suramin and nimodipine partially improved cell viability of DRGN after suramin exposure. In summary, we describe suramin-induced neurotoxic effects on DRGN as well as potentially neuroprotective agents targeting intracellular Ca2+ dyshomeostasis.

Behavioral outcome measures to improve experimental stroke research.

Functional recovery after an experimental stroke can be assessed by multiple behavioral tests, however, there is no consensus about which test to use in long-term stroke recovery studies or whether the tests are affected by stroke surgery, post-operative care or behavioral compensation due to repeated testing. This review describes the tests most commonly used to assess motor and sensorimotor function, cognition and mood in stroke animals. Although it is difficult to predict the direction of future research, it may be possible to prevent false-positive results by selecting an appropriate task or a battery of tasks. It is also expected that the upcoming stroke recovery recommendations and the improved dialogue between academy, industry and healthcare professionals will further promote translational success.

Interaction of ARC and Daxx: A Novel Endogenous Target to Preserve Motor Function and Cell Loss after Focal Brain Ischemia in Mice.

UNLABELLED: The aim of this study was to explore the signaling and neuroprotective effect of transactivator of transcription (TAT) protein transduction of the apoptosis repressor with CARD (ARC) in in vitro and in vivo models of cerebral ischemia in mice. In mice, transient focal cerebral ischemia reduced endogenous ARC protein in neurons in the ischemic striatum at early reperfusion time points, and in primary neuronal cultures, RNA interference resulted in greater neuronal susceptibility to oxygen glucose deprivation (OGD). TAT.ARC protein delivery led to a dose-dependent better survival after OGD. Infarct sizes 72 h after 60 min middle cerebral artery occlusion (MCAo) were on average 30 ± 8% (mean ± SD; p = 0.005; T2-weighted MRI) smaller in TAT.ARC-treated mice (1 µg intraventricularly during MCAo) compared with controls. TAT.ARC-treated mice showed better performance in the pole test compared with TAT.ß-Gal-treated controls. Importantly, post-stroke treatment (3 h after MCAo) was still effective in affording reduced lesion volume by 20 ± 7% (mean ± SD; p < 0.05) and better functional outcome compared with controls. Delayed treatment in mice subjected to 30 min MCAo led to sustained neuroprotection and functional behavior benefits for at least 28 d. Functionally, TAT.ARC treatment inhibited DAXX-ASK1-JNK signaling in the ischemic brain. ARC interacts with DAXX in a CARD-dependent manner to block DAXX trafficking and ASK1-JNK activation. Our work identifies for the first time ARC-DAXX binding to block ASK1-JNK activation as an ARC-specific endogenous mechanism that interferes with neuronal cell death and ischemic brain injury. Delayed delivery of TAT.ARC may present a promising target for stroke therapy. SIGNIFICANCE STATEMENT: Up to now, the only successful pharmacological target of human ischemic stroke is thrombolysis. Neuroprotective pharmacological strategies are needed to accompany therapies aiming to achieve reperfusion. We describe that apoptosis repressor with CARD (ARC) interacts and inhibits DAXX and proximal signals of cell death. In a murine stroke model mimicking human malignant infarction in the territory of the middle cerebral artery, TAT.ARC salvages brain tissue when given during occlusion or 3 h delayed with sustained functional benefits (28 d). This is a promising novel therapeutic approach because it appears to be effective in a model producing severe injury by interfering with an array of proximal signals and effectors of the ischemic cascade, upstream of JNK, caspases, and BIM and BAX activation.

Electrophysiological, behavioral and histological characterization of paclitaxel, cisplatin, vincristine and bortezomib-induced neuropathy in C57Bl/6 mice.

Polyneuropathy is a frequent and potentially severe side effect of clinical tumor chemotherapy. The goal of this study was to characterize paclitaxel-, cisplatin-, vincristine- and bortezomib-induced neuropathy in C57BL/6 mice with a comparative approach. The phenotype of the animals was evaluated at four time points with behavioral and electrophysiological tests, followed by histology. Treatment protocols used in this study were well tolerated and induced a sensory and predominantly axonal polyneuropathy. Behavioral testing revealed normal motor coordination, whereas all mice receiving verum treatment developed mechanical allodynia and distinct gait alterations. Electrophysiological evaluation showed a significant decrease of the caudal sensory nerve action potential amplitude for all cytostatic agents and a moderate reduction of nerve conduction velocity for cisplatin and paclitaxel. This finding was confirmed by histological analysis of the sciatic nerve which showed predominantly axonal damage: Paclitaxel and vincristine affected mostly large myelinated fibers, bortezomib small myelinated fibers and cisplatin damaged all types of myelinated fibers to a similar degree. Neuropathic symptoms developed faster in paclitaxel and vincristine treated animals compared to cisplatin and bortezomib treatment. The animal models in this study can be used to elucidate pathomechanisms underlying chemotherapy-induced polyneuropathy and for the development of novel therapeutic and preventative strategies.

Essential role of interleukin-6 in post-stroke angiogenesis.

Ambivalent effects of interleukin-6 on the pathogenesis of ischaemic stroke have been reported. However, to date, the long-term actions of interleukin-6 after stroke have not been investigated. Here, we subjected interleukin-6 knockout (IL-6(-/-)) and wild-type control mice to mild brain ischaemia by 30-min filamentous middle cerebral artery occlusion/reperfusion. While ischaemic tissue damage was comparable at early time points, IL-6(-/-) mice showed significantly increased chronic lesion volumes as well as worse long-term functional outcome. In particular, IL-6(-/-) mice displayed an impaired angiogenic response to brain ischaemia with reduced numbers of newly generated endothelial cells and decreased density of perfused microvessels along with lower absolute regional cerebral blood flow and reduced vessel responsivity in ischaemic striatum at 4 weeks. Similarly, the early genomic activation of angiogenesis-related gene networks was strongly reduced and the ischaemia-induced signal transducer and activator of transcription 3 activation observed in wild-type mice was almost absent in IL-6(-/-) mice. In addition, systemic neoangiogenesis was impaired in IL-6(-/-) mice. Transplantation of interleukin-6 competent bone marrow into IL-6(-/-) mice (IL-6(chi)) did not rescue interleukin-6 messenger RNA expression or the early transcriptional activation of angiogenesis after stroke. Accordingly, chronic stroke outcome in IL-6(chi) mice recapitulated the major effects of interleukin-6 deficiency on post-stroke regeneration with significantly enhanced lesion volumes and reduced vessel densities. Additional in vitro experiments yielded complementary evidence, which showed that after stroke resident brain cells serve as the major source of interleukin-6 in a self-amplifying network. Treatment of primary cortical neurons, mixed glial cultures or immortalized brain endothelia with interleukin 6-induced robust interleukin-6 messenger RNA transcription in each case, whereas oxygen-glucose deprivation did not. However, oxygen-glucose deprivation of organotypic brain slices resulted in strong upregulation of interleukin-6 messenger RNA along with increased transcription of key angiogenesis-associated genes. In conclusion, interleukin-6 produced locally by resident brain cells promotes post-stroke angiogenesis and thereby affords long-term histological and functional protection.

Acute neuroprotection by pioglitazone after mild brain ischemia without effect on long-term outcome.

Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonists (thiazolidinediones) have anti-inflammatory effects and improve endothelium function. Here, we analyzed the effects of pioglitazone on short- and longer-term outcome after mild transient brain ischemia. 129/SV mice were subjected to 30 min filamentous middle cerebral artery occlusion (MCAo), followed by reperfusion. Post event, animals were treated with daily intraperitoneal (i.p.) pioglitazone (20 mg/kg body weight) or vehicle. Pioglitazone given acutely after transient brain ischemia/reperfusion reduced lesion size and the number of Iba1-expressing microglia in the ischemic striatum at three days. In vitro, pioglitazone attenuated migration and proliferation of primary mouse microglia. However, analysis at 6 weeks after MCAo/reperfusion no longer yielded an effect of pioglitazone on either lesion size or Iba1+ cell counts. Regarding functional longer-term outcome, we also did not detect a beneficial effect of pioglitazone on motor function measured either on the pole test or the wire hanging test or on learning and memory in the Morris water maze. Our study thus underscores the importance of extending experimental stroke studies to an analysis of longer-term outcome.

Folate deficiency induces neurodegeneration and brain dysfunction in mice lacking uracil DNA glycosylase.

Folate deficiency and resultant increased homocysteine levels have been linked experimentally and epidemiologically with neurodegenerative conditions like stroke and dementia. Moreover, folate deficiency has been implicated in the pathogenesis of psychiatric disorders, most notably depression. We hypothesized that the pathogenic mechanisms include uracil misincorporation and, therefore, analyzed the effects of folate deficiency in mice lacking uracil DNA glycosylase (Ung-/-) versus wild-type controls. Folate depletion increased nuclear mutation rates in Ung-/- embryonic fibroblasts, and conferred death of cultured Ung-/- hippocampal neurons. Feeding animals a folate-deficient diet (FD) for 3 months induced degeneration of CA3 pyramidal neurons in Ung-/- but not Ung+/+ mice along with decreased hippocampal expression of brain-derived neurotrophic factor protein and decreased brain levels of antioxidant glutathione. Furthermore, FD induced cognitive deficits and mood alterations such as anxious and despair-like behaviors that were aggravated in Ung-/- mice. Independent of Ung genotype, FD increased plasma homocysteine levels, altered brain monoamine metabolism, and inhibited adult hippocampal neurogenesis. These results indicate that impaired uracil repair is involved in neurodegeneration and neuropsychiatric dysfunction induced by experimental folate deficiency.

Intravenous rosuvastatin for acute stroke treatment: an animal study.

BACKGROUND AND PURPOSE: Statins exert rapid cholesterol-independent vasoprotective effects. Here, we tested whether postevent treatment with intravenously (i.v.) administered rosuvastatin improves acute stroke outcome in mice. METHODS: 129/SV wild-type mice were subjected to 1-hour filamentous middle cerebral artery occlusion (MCAo), followed by reperfusion, and were postevent treated with i.v. or intraperitoneal (i.p.) rosuvastatin given up to 6 hours after MCAo (dose range 0.02 to 20 mg kg(-1) body weight). RESULTS: Rosuvastatin, when administered i.v., significantly reduced lesion size when given up to 4 hours after MCAo and in doses as low as 0.2 mg kg(-1). In contrast, i.p. administration provided protection only when given directly on reperfusion at a dose of 20 mg kg(-1) but not at lower doses or later time points. Lesion protection was evident as late as 5 days after brain ischemia and was associated with functional improvements in the pole-test and wire-hanging test (2.0 mg kg(-1) dose). Neuroprotection with i.v. rosuvastatin was achieved with peak plasma concentrations <0.5 ng ml(-1) (ie, with 0.2 mg kg(-1)) and was associated with increased levels of phosphorylated Akt kinase and endothelial nitric oxide synthase in the vasculature. CONCLUSIONS: Rosuvastatin, given intravenously at pharmacologically relevant concentrations, protects from focal brain ischemia up to 4 hours after an event. In our opinion, the development of an intravenous statin formulation is warranted for acute stroke trials with statins in humans.