Biology subjects

Hyacinth, H. I.

Publications and source records attributed to Hyacinth, H. I..

3 recordsLinked to original sources

bioRxiv2024

Neuroinflammation underlies the development of social stress induced cognitive deficit in sickle cell disease.

Cognitive deficit is a debilitating complication of SCD with multifactorial pathobiology. Here we show that neuroinflammation and dysregulation in lipidomics and transcriptomics profiles are major underlying mechanisms of social stress-induced cognitive deficit in SCD. Townes sickle cell (SS) mice and controls (AA) were exposed to social stress using the repeat social defeat (RSD) paradigm concurrently with or without treatment with minocycline. Mice were tested for cognitive deficit using novel object recognition (NOR) and fear conditioning (FC) tests. SS mice exposed to RSD without treatment had worse performance on cognitive tests compared to SS mice exposed to RSD with treatment or to AA controls, irrespective of their RSD or treatment disposition. Additionally, compared to SS mice exposed to RSD with treatment, SS mice exposed to RSD without treatment had significantly more cellular evidence of neuroinflammation coupled with a significant shift in the differentiation of neural progenitor cells towards astrogliogenesis. Additionally, brain tissue from SS mice exposed to RSD was significantly enriched for genes associated with blood-brain barrier dysfunction, neuron excitotoxicity, inflammation, and significant dysregulation in sphingolipids important to neuronal cell processes. We demonstrate in this study that neuroinflammation and lipid dysregulation are potential underlying mechanisms of social stress-related cognitive deficit in SS mice. Key PointsO_LINeuroinflammation and lipid dysfunction are potential underlying mechanisms of social stress-related cognitive deficit in SCD patients. C_LIO_LIMitigating or ameliorating the impact of cognitive deficits in SCD needs to consider the biological changes already created by exposure to social stress. C_LI Novelty of our FindingsWe show for the first time, that neuroinflammation along with changes in the brain lipidome and transcriptome, are underlying biological mechanism contributing to the development and potentially progression of cognitive impairment among sickle cell patients. These findings also provide for the first time, a mechanistic basis for an earlier reported observation of a higher likelihood of having lower intelligence quotient scores among children with sickle cell disease exposed to social stress in the form of low parental socioeconomic status.

neuroscience↗

bioRxiv2020

Age and neuroinflammation are important components of the mechanism of cognitive and neurobehavioral deficits in sickle cell disease.

ObjectivesCognitive and neurobehavioral abnormalities are the most common and complex complications of sickle cell disease (SCD). Known risk factors influencing abnormalities are stroke and silent cerebral infarcts, but a majority of cases do not have overt cerebral injury and the underlying mechanism is not well understood. This study aims to determine whether sickle cell mice could recapitulate features of cognitive and neurobehavioral impairment observed in sickle cell patients as well as to determine the underlying cellular mechanism of these SCD complications. MethodsUsing a longitudinal cross-sectional study design, we evaluated cognition and neurobehavioral deficits as an outcome. Six as well as 13 months old male Townes humanized sickle cell (SS) and matched control (AA) mice were tested. The combination of novel object recognition and fear conditioning tests was employed to measure anxiety/depression, learning and memory. Immunohistochemistry was performed to quantify bone marrow-derived microglia (CD45+) and activated microglia (Iba1+) in the dentate and peri-dentate gyrus to determine if these factors were potential pathogenic mechanisms associated with cognitive and neurobehavioral abnormalities. We evaluated neurogenesis by measuring 5Bromodeoxyuridine (BrdU) and doublecortin (DCX) and phenotyped proliferating cells via quantification of glial fibrillary acid protein (GFAP+), neuronal nuclei (NeuN+), CD45+ and Iba1+. In addition, Golgi-Cox staining was used to assess neuroplasticity via measurement of dendritic spine density and morphology, as well as dendrite arbors. ResultsCompared to matched AA, 13 months old SS mice showed significant evidence of anxiety/depression by the shorter distance traveled as well as thigmotaxis. Additionally, SS mice were significantly less likely to recognize the novel object as well as have a reduced preference for the novel object. There were no significant differences between 6 months old SS and AA. But the difference reappeared after the same mice were aged to 13 months. Aged mice exhibited more anxiety/depression behaviors and thigmotaxis and were less likely to recognize or show a lower percent preference for the novel object compared to aged control (AA) mice. Immunohistochemistry analysis shows that sickle cell (SS) mice had significantly more CD45+ and Iba1+ activated microglia cells in the dentate and peri-dentate gyrus area compared to AA mice. SS mice also had a significantly lower dendritic spine density compared with controls. Treatment of aged SS mice with minocycline resulted in significant improvement of cognitive and neurobehavioral function compared to matched vehicle-treated SS mice. Also immunohistochemical and histological analysis showed that treated SS mice had significantly fewer CD45+ cells and activated microglia in the dentate and peri-dentate gyrus area. Furthermore, there was significant improvement in dendritic spine and dendrite arbor density as well as spine maturation in treated sickle cell mice compared with vehicle-treated sickle cell mice. ConclusionTaken together these results indicate that age, neuro-inflammation and neuroplasticity, specifically, spine maturation and density, are possible mechanisms underlying cognition deficits in sickle cell disease. These could also be targeted as a potential approach for prevention and or treatment of cognitive and neurobehavioral deficits in SCD.

neuroscience↗

bioRxiv2017

Spontaneous development of cerebrovascular pathology and microinfarcts in a mouse model of sickle cell disease.

Stroke is a dramatic complication of sickle cell disease (SCD) and is associated with aneurysms, moya moya, intravascular thrombi, cerebral hyperemia and increased vessel tortuosity. We show that aged SCD mice spontaneously develop the characteristics features of cerebral vasculopathy seen in human SCD. Thirteen month old Townes SCD mice and age-matched controls had a cranial windows implanted over the somatosensory cortex. Cortical capillaries were imaged using in vivo two-photon microscopy after the blood plasma was labeled with a fluorescent dye. Results showed that SCD mice compared to controls, had significantly higher red blood cell (RBC) velocity and capillary vessel diameter. SCD mice also had a significantly higher number of occlusive events in the capillary bed, resulting in more stalling of RBC flow. Microvascular topology was also altered, as SCD mice had significantly higher vessel tortuosity and shorter capillary branch lengths. Finally, post-mortem analyses revealed a greater number of cortical microinfarcts, likely caused by vascular occlusion since local tissue hypoxia and blood-brain barrier leakage was prominent. We concluded that aged Townes sickle cell mice spontaneously develop SCD-associated cerebral vasculopathy, and that in vivo two-photon imaging is a powerful approach to investigate the mechanisms of vascular complications in SCD.

neuroscience↗