A PrP EGFR signaling axis controls neural stem cell senescence through modulating cellular energy pathways.

Mis-folding of the prion protein (PrP) is known to cause neurodegenerative disease; however, the native function of this protein remains poorly defined. PrP has been linked with many cellular functions, including cellular proliferation and senescence. It is also known to influence epidermal growth factor receptor (EGFR) signaling, a pathway that is itself linked with both cell growth and senescence. Adult neural stem cells (NSCs) persist at low levels in the brain throughout life and retain the ability to proliferate and differentiate into new neural lineage cells. KO of PrP has previously been shown to reduce NSC proliferative capacity. We used PrP KO and WT NSCs from adult mouse brain to examine the influence of PrP on cellular senescence, EGFR signaling, and the downstream cellular processes. PrP KO NSCs showed decreased cell proliferation and increased senescence in in vitro cultures. Expression of EGFR was decreased in PrP KO NSCs compared with WT NSCs and additional supplementation of EGF was sufficient to reduce senescence. RNA-seq analysis confirmed that significant changes were occurring at the mRNA level within the EGFR signaling pathway and these were associated with reduced expression of mitochondrial components and correspondingly reduced mitochondrial function. Metabolomic analysis of cellular energy pathways showed that blockages were occurring at critical sites for production of energy and biomass, including catabolism of pyruvate. We conclude that, in the absence of PrP, NSC growth pathways are downregulated as a consequence of insufficient energy and growth intermediates.

Temporary alteration of neuronal network communication is a protective response to redox imbalance that requires GPI-anchored prion protein.

Cellular prion protein (PrPC) protects neurons against oxidative stress damage. This role is lost upon its misfolding into insoluble prions in prion diseases, and correlated with cytoskeletal breakdown and neurophysiological deficits. Here we used mouse neuronal models to assess how PrPC protects the neuronal cytoskeleton, and its role in network communication, from oxidative stress damage. Oxidative stress was induced extrinsically by potassium superoxide (KO2) or intrinsically by Mito-Paraquat (MtPQ), targeting the mitochondria. In mouse neural lineage cells, KO2 was damaging to the cytoskeleton, with cells lacking PrPC (PrP-/-) damaged more than wild-type (WT) cells. In hippocampal slices, KO2 acutely inhibited neuronal communication in WT controls without damaging the cytoskeleton. This inhibition was not observed in PrP-/- slices. Neuronal communication and the cytoskeleton of PrP-/- slices became progressively disrupted and degenerated post-recovery, whereas the dysfunction in WT slices recovered in 5 days. This suggests that the acute inhibition of neuronal activity in WT slices in response to KO2 was a neuroprotective role of PrPC, which PrP-/- slices lacked. Heterozygous expression of PrPC was sufficient for this neuroprotection. Further, hippocampal slices from mice expressing PrPC without its GPI anchor (PrPGPI-/-) displayed acute inhibition of neuronal activity by KO2. However, they failed to restore normal activity and cytoskeletal formation post-recovery. This suggests that PrPC facilitates the depressive response to KO2 and its GPI anchoring is required to restore KO2-induced damages. Immuno spin-trapping showed increased radicals formed on the filamentous actin of PrP-/- and PrPGPI-/- slices, but not WT and PrP+/- slices, post-recovery suggesting ongoing dysregulation of redox balance in the slices lacking GPI-anchored PrPC. The MtPQ treatment of hippocampal slices temporarily inhibited neuronal communication independent of PrPC expression. Overall, GPI-anchored PrPC alters synapses and neurotransmission to protect and repair the neuronal cytoskeleton, and neuronal communication, from extrinsically induced oxidative stress damages.

Hereditary E200K mutation within the prion protein gene alters human iPSC derived cardiomyocyte function.

Cardiomyopathy is a co-morbidity of some prion diseases including genetic disease caused by mutations within the PrP gene (PRNP). Although the cellular prion protein (PrP) has been shown to protect against cardiotoxicity caused by oxidative stress, it is unclear if the cardiomyopathy is directly linked to PrP dysfunction. We differentiated cardiomyocyte cultures from donor human induced pluripotent stem cells and found a direct influence of the PRNP E200K mutation on cellular function. The PRNP E200K cardiomyocytes showed abnormal function evident in the irregularity of the rapid repolarization; a phenotype comparable with the dysfunction reported in Down Syndrome cardiomyocytes. PRNP E200K cardiomyocyte cultures also showed increased mitochondrial superoxide accompanied by increased mitochondrial membrane potential and dysfunction. To confirm that the changes were due to the E200K mutation, CRISPR-Cas9 engineering was used to correct the E200K carrier cells and insert the E200K mutation into control cells. The isotype matched cardiomyocytes showed that the lysine expressing allele does directly influence electrophysiology and mitochondrial function but some differences in severity were apparent between donor lines. Our results demonstrate that cardiomyopathy in hereditary prion disease may be directly linked to PrP dysfunction.

Impact of Early Video Capsule Endoscopy on Hospitalization and Post-hospitalization Outcomes: A Propensity Score-Matching Analysis.

INTRODUCTION: Video capsule endoscopy (VCE) has become the accepted evaluation of choice for patients with suspected small bowel bleeding. Our aim was to evaluate the impact of early as compared to delayed inpatient VCE on post-index hospitalization readmission rates. METHODS: We performed a retrospective study using medical claims from the IBM® Marketscan® Commercial Database from January 1, 2004, through September 30, 2018, including adult patients that underwent an inpatient VCE. Early VCE was defined as occurring on days 0, 1, or 2 of the index hospitalizations, whereas delayed VCE was performed on days 3-7. Propensity matching was performed to create an analytic cohort, and outcomes were assessed using logistic regression. RESULTS: Following propensity score matching, 607 patients undergoing early VCE were matched 1:1 with 607 patients undergoing delayed VCE. The median patient age was 65 (IQR: 56-78) years, and 560 (37.9%) of the included patients were female. The mean time to VCE was 1.6 (± 0.6) days for the early VCE group and 4.0 (± 1.2) days from admission for delayed VCE. In unadjusted comparisons, we found no significant difference between early VCE and delayed VCE with respect to 90-day all-cause readmission (18.6% vs. 17.0%, P = 0.5) or 90-day rebleeding risk (10.5% vs. 8.7%, P = 0.331). Patients undergoing an early VCE had a shorter hospital LOS and less total hospitalization charges. CONCLUSION: Early as compared to delayed inpatient VCE was associated with a reduction in index hospitalization resource utilization. No differences were found with respect to reductions in readmissions or rebleeding events.

Neuronal excitatory-to-inhibitory balance is altered in cerebral organoid models of genetic neurological diseases.

The neuro-physiological properties of individuals with genetic pre-disposition to neurological disorders are largely unknown. Here we aimed to explore these properties using cerebral organoids (COs) derived from fibroblasts of individuals with confirmed genetic mutations including PRNPE200K, trisomy 21 (T21), and LRRK2G2019S, which are associated with Creutzfeldt Jakob disease, Down Syndrome, and Parkinson's disease. We utilized no known disease/healthy COs (HC) as normal function controls. At 3-4 and 6-10 months post-differentiation, COs with mutations showed no evidence of disease-related pathology. Electrophysiology assessment showed that all COs exhibited mature neuronal firing at 6-10 months old. At this age, we observed significant changes in the electrophysiology of the COs with disease-associated mutations (dCOs) as compared with the HC, including reduced neuronal network communication, slowing neuronal oscillations, and increased coupling of delta and theta phases to the amplitudes of gamma oscillations. Such changes were linked with the detection of hypersynchronous events like spike-and-wave discharges. These dysfunctions were associated with altered production and release of neurotransmitters, compromised activity of excitatory ionotropic receptors including receptors of kainate, AMPA, and NMDA, and changed levels and function of excitatory glutamatergic synapses and inhibitory GABAergic synapses. Neuronal properties that modulate GABAergic inhibition including the activity of Na-K-Cl cotransport 1 (NKCC1) in Cl- homeostasis and the levels of synaptic and extra-synaptic localization of GABA receptors (GABARs) were altered in the T21 COs only. The neurosteroid allopregnanolone, a positive modulator of GABARs, was downregulated in all the dCOs. Treatment with this neurosteroid significantly improved the neuronal communication in the dCOs, possibly through improving the GABAergic inhibition. Overall, without the manifestation of any disease-related pathology, the genetic mutations PRNPE200K, T21, and LRRK2G2019S significantly altered the neuronal network communication in dCOs by disrupting the excitatory-to-inhibitory balance.

Role of Microglia and Astrocytes in Spinal Cord Injury Induced Neuropathic Pain.

Background: Spinal cord injuries incite varying degrees of symptoms in patients, ranging from weakness and incoordination to paralysis. Common amongst spinal cord injury (SCI) patients, neuropathic pain (NP) is a debilitating medical condition. Unfortunately, there remain many clinical impediments in treating NP because there is a lack of understanding regarding the mechanisms behind SCI-induced NP (SCINP). Given that more than 450,000 people in the United States alone suffer from SCI, it is unsatisfactory that current treatments yield poor results in alleviating and treating NP. Summary: In this review, we briefly discussed the models of SCINP along with the mechanisms of NP progression. Further, current treatment modalities are herein explored for SCINP involving pharmacological interventions targeting glia cells and astrocytes. Key message: The studies presented in this review provide insight for new directions regarding SCINP alleviation. Given the severity and incapacitating effects of SCINP, it is imperative to study the pathways involved and find new therapeutic targets in coordination with stem cell research, and to develop a new gold-standard in SCINP treatment.

Comparative Morphometry of the Wisconsin Miniature SwineTM Thoracic Spine for Modeling Human Spine in Translational Spinal Cord Injury Research.

BACKGROUND/AIMS: Spine and spinal cord pathologies and associated neuropathic pain are among the most complex medical disorders to treat. While rodent models are widely used in spine and spinal cord research and have provided valuable insight into pathophysiological mechanisms, these models offer limited translatability. Thus, studies in rodent models have not led to the development of clinically effective therapies. More recently, swine has become a favored model for spine research because of the high congruency of the species to humans with respect to spine and spinal cord anatomy, vasculature, and immune responses. However, conventional breeds of swine commonly used in these studies present practical and translational hurdles due to their rapid growth toward weights well above those of humans. METHODS: In the current study, we evaluated the suitability of a human-sized breed of swine developed at the University of Wisconsin-Madison, the Wisconsin Miniature SwineTM (WMSTM), in the context of thoracic spine morphometry for use in research to overcome limitations of conventional swine breeds. The morphometry of thoracic vertebrae (T1-T15) of 5-6 months-old WMS was analyzed and compared to published values of human and conventional swine spines. RESULTS: The key finding of this study is that WMS spine more closely models the human spine for many of the measured vertebrae parameters, while being similar to conventional swine in respect to the other parameters. CONCLUSION: WMS provides an improvement over conventional swine for use in translational spinal cord injury studies, particularly long-term ones, because of its slower rate of growth and its maximum growth being limited to human weight and size.