Sex-Specific Differences in Autophagic Responses to Experimental Ischemic Stroke.

Ischemic stroke triggers a series of complex pathophysiological processes including autophagy. Differential activation of autophagy occurs in neurons derived from males versus females after stressors such as nutrient deprivation. Whether autophagy displays sexual dimorphism after ischemic stroke is unknown. We used a cerebral ischemia mouse model (middle cerebral artery occlusion, MCAO) to evaluate the effects of inhibiting autophagy in ischemic brain pathology. We observed that inhibiting autophagy reduced infarct volume in males and ovariectomized females. However, autophagy inhibition enhanced infarct size in females and in ovariectomized females supplemented with estrogen compared to control mice. We also observed that males had increased levels of Beclin1 and LC3 and decreased levels of pULK1 and p62 at 24 h, while females had decreased levels of Beclin1 and increased levels of ATG7. Furthermore, the levels of autophagy markers were increased under basal conditions and after oxygen and glucose deprivation in male neurons compared with female neurons in vitro. E2 supplementation significantly inhibited autophagy only in male neurons, and was beneficial for cell survival only in female neurons. This study shows that autophagy in the ischemic brain differs between the sexes, and that autophagy regulators have different effects in a sex-dependent manner in neurons.

Treating Paroxysmal Sympathetic Hyperactivity With Enteral Baclofen in Anoxic Brain Injury.

INTRODUCTION: Paroxysmal sympathetic hypersensitivity (PSH) has become more frequently recognized in patients with severe neurological brain injury. Left untreated, PSH has been associated with poor neurological outcomes. Currently, most therapeutic options are circumstantial with evidence stemming from subjective case reports. CASE SERIES: Two young females were admitted after cardiac arrest and found to have anoxic brain injury with subsequent PSH. Initial treatment was targeted at relief of the hyperadrenergic symptoms, which included bromocriptine, propranolol, opioids and benzodiazepines. These therapies were minimally effective, and the patients remained comatose. After initiation of enteral baclofen treatment, they exhibited drastic reduction of PSH symptoms and became alert and interactive. After a 6-week hospital stay, they were both discharged to long-term rehabilitation centers. CONCLUSION: This case series reviews the current therapies used for PSH and discusses 2 patients with uncontrolled PSH secondary to anoxic brain injury. Both patients arose from coma and had significant symptomatic improvement with enteral baclofen treatment. Thus, enteral baclofen should be considered as a primary treatment for PSH to prevent sustained symptoms and prolonged hospitalizations.

Depletion of CD4 T cells provides therapeutic benefits in aged mice after ischemic stroke.

T-lymphocytes have a multifaceted role in ischemic stroke, but the majority of studies have been conducted in young mice, which may limit the translational value of these findings. Previous studies have shown that aging results in T cell dysfunction, leading to enhanced production of pro-inflammatory cytokines and chemokines, including interferon gamma (IFN-γ) and interferon-gamma-inducible protein (IP-10). This study assessed the role of T cells and pro-inflammatory factors on histologic and functional outcomes in an aged mouse model. Levels of IP-10 were measured in the brain and serum of young and aged male mice following middle cerebral artery occlusion (MCAo) or sham surgery. Additionally, IP-10 levels were evaluated in stroke patients. To directly determine the role of brain-infiltrating T cells after stroke, a separate cohort of aged male and female animals received either an anti-CD4 depletion antibody or IgG isotype control at 72 and 96 h following experimental stroke. Behavioral assessments were performed on day 7 post-MCAo. CD4 T cell depletion resulted in improved behavioral outcomes, despite the lack of differences in infarct size between the isotype control and anti-CD4 antibody treated stroke groups. Circulating IP-10 levels were increased in both humans and mice with age and stroke, and depletion of CD4 T cells led to a reduction in IFN-γ and IP-10 levels in mice. Since anti-CD4 treatment was administered three days after stroke onset, targeting this inflammatory pathway may be beneficial to aged stroke patients who present outside of the current time window for thrombolysis and thrombectomy.

Thyroid hormones and functional outcomes after ischemic stroke.

BACKGROUND: Stroke is the fifth leading cause of death and the primary cause of long-term adult disability in the United States. Increasing evidence suggests that low T3 levels immediately following acute ischemic stroke are associated with greater stroke severity, higher mortality rates, and poorer functional outcomes. Prognosis is also poor in critically ill hospitalized patients who have non-thyroidal illness syndrome (NTIS), where T3 levels are low, but TSH is normal. However, data regarding the association between TSH levels and functional outcomes are contradictory. Thus, this study investigated the role of TSH on stroke outcomes, concomitantly with T3 and T4. FINDINGS: In this work, blood was collected from patients with radiologically confirmed acute ischemic stroke at 24±6 hours post-symptom onset and serum levels of TSH, free T3, and free T4 were measured. Stroke outcomes were measured at discharge, 3 and 12 months using the modified Rankin scale and modified Barthel Index as markers of disability. Though we found that lower levels of free T3 were associated with worse prognosis at hospital discharge, and at 3 and 12 months post-stroke, none of these outcomes held after multivariate analysis. Thus, it is likely that thyroid hormones are associated with other factors that impact stroke outcomes, such as sex, age and stroke etiology. CONCLUSIONS: This study found that lower levels of free T3 were associated with poorer outcomes at hospital discharge, and at 3 and 12 months post stroke, however, these associations diminished after correction for other known predictors of stroke outcome. Thyroid hormones have a complex relationship with ischemic stroke and stroke recovery, which merits further larger investigations.

Inhibition of mitochondrial p53 abolishes the detrimental effects of social isolation on ischemic brain injury.

BACKGROUND AND PURPOSE: Social isolation (SI) increases stroke incidence and delays poststroke recovery. Women may be at greater risk from the negative consequences of SI, but few studies have examined both sexes in experimental models, and none have evaluated the effects of isolation initiated after stroke. The effects of poststroke SI in men and women were examined, and the role of mitochondrial P53 was evaluated. METHODS: C57Bl6 mice were pair-housed (PH; male and ovariectomized female) for 2 weeks, subjected to stroke and then assigned to a housing condition (isolated or PH). The effects of housing on infarct volume and recovery were examined. Changes in Bcl-2 and mitochondrial p53 were assessed by Western blot. A mitochondrial p53 inhibitor (pifithrin-µ) was given to mice of both sexes. RESULTS: Compared with pair-housed mice, poststroke SI significantly increased infarct size in both sexes; SI mice also had worse neurological deficits. The detrimental effects of SI paralleled increases in mitochondrial p53 levels. Pharmacological inhibition of mitochondrial p53 using pifithrin-µ abolished the detrimental effects of SI and reduced cell death. CONCLUSIONS: Poststroke SI results in increased ischemic injury in both sexes. The effect of housing on infarct was more pronounced in women. Targeting the mitochondrial P53 pathway could minimize the detrimental effects of isolation after stroke.

Social isolation after stroke leads to depressive-like behavior and decreased BDNF levels in mice.

Social isolation prior to stroke leads to poorer outcomes after an ischemic injury in both animal and human studies. However, the impact of social isolation following stroke, which may be more clinically relevant as a target for therapeutic intervention, has yet to be examined. In this study, we investigated both the sub-acute (2 weeks) and chronic (7 weeks) effects of social isolation on post-stroke functional and histological outcome. Worsened histological damage from ischemic injury and an increase in depressive-like behavior was observed in isolated mice as compared to pair-housed mice. Mice isolated immediately after stroke showed a decrease in the levels of brain-derived neurotrophic factor (BDNF). These changes, both histological and behavioral, suggest an overall negative effect of social isolation on stroke outcome, potentially contributing to post-stroke depression and anxiety. Therefore, it is important to identify patients who have perceived isolation post-stroke to hopefully prevent this exacerbation of histological damage and subsequent depression.