Prions cause transmissible spongiform encephalopathies for which no treatment exists. Prions consist of PrP^Sc, a misfolded and aggregated form of the cellular prion protein (PrP^C). We explore the antiprion properties of luminescent conjugated polythiophenes (LCPs) that bind and stabilize ordered protein aggregates. By administering a library of structurally diverse LCPs to the brains of prion-infected mice via osmotic minipumps, we found that antiprion activity required a minimum of five thiophene rings bearing regularly spaced carboxyl side groups. Solid-state nuclear magnetic resonance analyses and molecular dynamics simulations revealed that anionic side chains interacted with complementary, regularly spaced cationic amyloid residues of model prions. These findings allowed us to extract structural rules governing the interaction between LCPs and protein aggregates, which we then used to design a new set of LCPs with optimized binding. The new set of LCPs showed robust prophylactic and therapeutic potency in prion-infected mice, with the lead compound extending survival by >80% and showing activity against both mouse and hamster prions as well as efficacy upon intraperitoneal administration into mice. These results demonstrate the feasibility of targeted chemical design of compounds that may be useful for treating diseases of aberrant protein aggregation such as prion disease.

Prions cause neurodegeneration in vivo, yet prion-infected cultured cells do not show cytotoxicity. This has hampered mechanistic studies of prion-induced neurodegeneration. Here we report that prion-infected cultured organotypic cerebellar slices (COCS) experienced progressive spongiform neurodegeneration closely reproducing prion disease, with three different prion strains giving rise to three distinct patterns of prion protein deposition. Neurodegeneration did not occur when PrP was genetically removed from neurons, and a comprehensive pharmacological screen indicated that neurodegeneration was abrogated by compounds known to antagonize prion replication. Prion infection of COCS and mice led to enhanced fodrin cleavage, suggesting the involvement of calpains or caspases in pathogenesis. Accordingly, neurotoxicity and fodrin cleavage were prevented by calpain inhibitors but not by caspase inhibitors, whereas prion replication proceeded unimpeded. Hence calpain inhibition can uncouple prion replication from its neurotoxic sequelae. These data validate COCS as a powerful model system that faithfully reproduces most morphological hallmarks of prion infections. The exquisite accessibility of COCS to pharmacological manipulations was instrumental in recognizing the role of calpains in neurotoxicity, and significantly extends the collection of tools necessary for rigorously dissecting prion pathogenesis. Transmissible spongiform encephalopathies (TSEs) are a group of fatal protein misfolding diseases causing neurodegeneration in vivo. TSEs are unique in that the infectious agent termed ‘prion’ consists of a misfolded protein lacking sequence specific nucleic acids. Prion-infected cultured cells do not develop visible pathological changes, and this has hampered mechanistic studies of prion-induced neurodegeneration. Here, we have developed a prion-induced neurodegeneration model that uses cultured slices of living brain tissue. Such slices display all the classical hallmark of prion disease, namely prion replication, inflammation, spongiform changes and neurodegeneration. Neurotoxicity is blocked by anti-prion drugs by reducing prion replication. We demonstrate for the first time an involvement of calcium-regulated cysteine proteases called calpains in driving neurotoxicity. We find that the proteolytic processing of the calpain substrate is induced by prion infection and blocked by calpain inhibitors without prion replication being affected. The assay system developed here allows for precise dissection of the mechanisms of prion-induced degeneration with pharmacological means.

Background and Purpose: The purpose of this study was to investigate the natural course of cerebral cavernous malformations (CCM) in the pediatric population, with special emphasis on the risk of first and recurrent bleeding over a 5-year period. Methods: Our institutional database was screened for patients with CCM treated between 2003 and 2020. Patients ≤18 years of age with complete magnetic resonance imaging data set, clinical baseline characteristics, and ≥1 follow-up examination were included. Surgically treated individuals were censored after CCM removal. We assessed the impact of various parameters on first or recurrent intracerebral hemorrhage (ICH) at diagnosis using univariate and multivariate logistic regression adjusted for age and sex. Kaplan-Meier and Cox regression analyses were performed to determine the cumulative 5-year risk for (re)hemorrhage. Results: One hundred twenty-nine pediatric patients with CCM were analyzed. Univariate logistic regression identified brain stem CCM (odds ratio, 3.15 [95% CI, 1.15−8.63]; P =0.026) and familial history of CCM (odds ratio, 2.47 [95% CI, 1.04−5.86]; P =0.041) as statistically significant predictors of ICH at diagnosis. Multivariate logistic regression confirmed this correlation (odds ratio, 3.62 [95% CI, 1.18−8.99]; P =0.022 and odds ratio, 2.53 [95% CI, 1.07−5.98]; P =0.035, respectively). Cox regression analysis identified ICH as mode of presentation (hazard ratio, 14.01 [95% CI, 1.80−110.39]; P =0.012) as an independent predictor for rehemorrhage during the 5-year follow-up. The cumulative 5-year risk of (re)bleeding was 15.9% (95% CI, 10.2%−23.6%) for the entire cohort, 30.2% (20.2%−42.3%) for pediatric patients with ICH at diagnosis, and 29.5% (95% CI, 13.9%−51.1%) for children with brain stem CCM. Conclusions: Pediatric patients with brain stem CCM and familial history of CCM have a higher risk of ICH as mode of presentation. During untreated 5-year follow-up, they revealed a similar risk of (re)hemorrhage compared to adult patients. The probability of (re)bleeding increases over time, especially in cases with ICH at presentation or brain stem localization.

Background and Purpose: This study aims to assess the influence of modifiable cardiovascular risk factors on hemorrhage risk of sporadic cerebral cavernous malformations (CCMs). Methods: From 1219 consecutive CCM patients (2003–2018), adult subjects with sporadic CCM and complete magnetic resonance imaging were included. We evaluated presence of intracerebral hemorrhage (ICH) as mode of presentation, occurrence of ICH during follow-up and risk factors arterial hypertension, diabetes, hyperlipidemia, nicotine abuse, and obesity (body mass index >30 kg/m ² ). Impact of risk factors on ICH at presentation was calculated using univariate and multivariate logistic regression with age and sex adjustment. We performed Kaplan-Meier and Cox regression to analyze cumulative 5-year risk for (re)bleeding. Results: We included 682 patients with CCM. The univariate logistic regression showed a significant relationship (odds ratio=1.938 [95% CI, 1.120–3.353], P =0.018) between obesity and ICH as mode of presentation. Multivariate adjusted logistic regression confirmed significant correlation with odds ratio=1.902 (95% CI, 1.024–3.532, P =0.042). Cox regression did not identify predictors for occurrence of (re)hemorrhage ( P >0.05; hazard ratios: arterial hypertension 1.112 [95% CI, 0.622–1.990], diabetes 0.850 [95% CI, 0.208–3.482], hyperlipidemia 0.719 [95% CI, 0.261–1.981], nicotine abuse 1.123 [95% CI, 0.591–2.134], and obesity 0.928 [95% CI, 0.416–2.070]). Conclusions: This study provides evidence that obesity may be a risk factor for CCM hemorrhage. It was significantly associated with ICH as mode of presentation. Other risk factors (arterial hypertension, diabetes, hyperlipidemia, and current nicotine abuse) showed no such effect. None of the factors showed to be independent predictors for cumulative 5-year risk of (re)bleeding.

Background and Purpose: Analyze and compare the natural course of confirmed familial cerebral cavernous malformation (FCCM), assumed FCCM and non‐familial multiple cerebral cavernous malformation (CCM) disease over a 5‐year period.Methods: Our institutional database was screened for patients with CCM admitted between 2003 and 2020. Patients with complete magnetic resonance imaging dataset, evidence of multiple CCM, clinical baseline characteristics, and follow‐up examination were included. Patients were separated into confirmed familial cases, assumed familial cases or non‐familial multiple cavernous malformations. Kaplan–Meier and Cox regression analyses were performed to determine the cumulative 5‐year risk for hemorrhage and recurrent hemorrhage.Results: A total of 238 patients with multiple CCM were analyzed; 90 individuals had a confirmed FCCM disease, 115 an assumed FCCM, and 33 were allocated to the non‐FCCM group. Univariate Cox regression analysis identified intracerebral hemorrhage (ICH) as mode of presentation (p = 0.001) as a predictor for occurrence of recurrent hemorrhage during the 5‐year follow‐up (FU). The cumulative 5‐year risk of (re)bleeding was 21.6% for the entire cohort, 30.7% for patients with ICH at diagnosis, 22.1% for those patients with a confirmed diagnosis of FCCM, 23.5% for those with an assumed FCCM, and 21% for the non‐FCCM cases.Conclusions: FCCM patients with ICH at diagnosis are prone to develop rebleeding. During untreated 5‐year FU, FCCM patients and patients with sporadic multiple CCM reveal an almost equal susceptibility for (re)hemorrhage. Moreover, confirmed, assumed and non‐FCCM patients showed an equal cumulative 5‐year risk of symptomatic ICH. The probability of hemorrhage tends to increase over time, particularly in cases with ICH at presentation.