Recent prevalence of acquired forms of transmissible spongiform encephalopathies (TSEs) has urged the development of early diagnostic measures as well as therapeutic interventions. To extend our ...previous findings on the value of amyloid imaging probes for these purposes, styrylbenzoazole derivatives with better permeability of blood–brain barrier (BBB) were developed and analyzed in this study. The new styrylbenzoazole compounds clearly labeled prion protein (PrP) plaques in brain specimens from human TSE in a manner irrespective of pathogen strain, and a representative compound BF‐168 detected abnormal PrP aggregates in the brain of TSE‐infected mice when the probe was injected intravenously. On the other hand, most of the compounds inhibited abnormal PrP formation in TSE‐infected cells with IC50 values in the nanomolar range, indicating that they represent one of the most potent classes of inhibitor ever reported. BF‐168 prolonged the lives of mice infected intracerebrally with TSE when the compound was given intravenously at the preclinical stage. The new compounds, however, failed to detect synaptic PrP deposition and to show pathogen‐independent therapeutic efficacy, similar to the amyloid imaging probes we previously reported. The compounds were BBB permeable and non‐toxic at doses for imaging and treatment; therefore, they are expected to be of practical use in human TSE.
It is desirable to make the diagnosis in live cattle with bovine spongiform encephalopathy (BSE), and thus surrogate markers for the disease have been eagerly sought. Serum proteins from BSE cattle ...were analyzed by 2-D Western blotting and TOF-MS. Autoantibodies against proteins in cytoskeletal fractions prepared from normal bovine brains were found in the sera of BSE cattle. The protein recognized was identified to be glial fibrillary acidic protein (GFAP), which is expressed mainly in astrocytes in the brain. The antigen protein, GFAP, was also found in the sera of BSE cattle. The percentages of both positive sera in the autoantibody and GFAP were 44.0% for the BSE cattle, 0% for the healthy cattle, and 5.0% for the clinically suspected BSE-negative cattle. A significant relationship between the presence of GFAP and the expression of its autoantibody in the serum was recognized in the BSE cattle. These findings suggest a leakage of GFAP into the peripheral blood during neurodegeneration associated with BSE, accompanied by the autoantibody production, and might be useful in understanding the pathogenesis and in developing a serological diagnosis of BSE in live cattle.
Glycosaminoglycans reportedly play important roles in prion formation, but because of their structural complexity, the chemical structures affecting prion formation have not been fully evaluated. ...Here, we compared two types of low molecular weight heparins and found that heparinase I-sensitive structures influenced anti-prion activity in prion-infected cells. Surface plasmon resonance analyses showed significant binding of a representative heparinase I substrate disaccharide unit, GlcNS6S-IdoA2S, to recombinant prion protein (PrP) fragments, such as full-length PrP23–231 and N-terminal domain PrP23–89, but not to PrP89–230. This binding was competitively inhibited by heparin or pentosan polysulfate, but not by Cu2+. These PrP binding profiles of the disaccharide unit are consistent with those previously reported for heparin. However, synthetic compounds comprising disaccharide unit alone or its multimers exhibited no anti-prion activity in prion-infected cells. Consequently, the findings suggest that the heparin disaccharide unit that binds to the N-terminal region of PrP is a key structure, but it is insufficient for exerting anti-prion activity.
•We studied heparin structures that affect prion formation in prion-infected cells.•Heparinase I-sensitive structures are needed for anti-prion activity of heparin.•A heparinase I substrate disaccharide unit binds the N-terminal domain of PrP.•Synthetic compounds made of disaccharide unit or multimers show no anti-prion activity.•The disaccharide unit is important but insufficient to exert anti-prion activity.
•Secretin receptor signaling modifies prion formation in prion-infected cells.•Secretin receptor deficiency modifies disease progression in prion-infected mice.•Our findings may provide insight into ...gender specific-effects that occur in certain prion diseases.
The cellular mechanisms behind prion biosynthesis and metabolism remain unclear. Here we show that secretin signaling via the secretin receptor regulates abnormal prion protein formation in prion-infected cells. Animal studies demonstrate that secretin receptor deficiency slightly, but significantly, prolongs incubation time in female but not male mice. This gender-specificity is consistent with our finding that prion-infected cells are derived from females. Therefore, our results provide initial insights into the reasons why age of disease onset in certain prion diseases is reported to occur slightly earlier in females than males.
Prion diseases are fatal transmissible neurodegenerative disorders. Among known anti-prions, hydroxypropyl methylcellulose compounds (HPMCs) are unique in their chemical structure and action. They ...have several excellent anti-prion properties but the effectiveness depends on the prion-infected mouse model. In the present study, we investigated the effects of stearoxy-modified HPMCs on prion-infected cells and mice. Stearoxy modification improved the anti-prion efficacy of HPMCs in prion-infected cells and significantly prolonged the incubation period in a lower HPMC-responding mouse model. However, stearoxy modification showed no improvement over nonmodified HPMCs in an HPMC-responding mouse model. These results offer a new line of inquiry for use with prion-infected mice that do not respond well to HPMCs.
Display omitted
Prion diseases are fatal transmissible neurodegenerative disorders. Tremendous efforts have been made for prion diseases; however, no effective treatment is available. Several anti-prion compounds ...have a preference for which prion strains or prion-infected animal models to target. Styrylbenzoazole compound called cpd-B is effective in RML prion-infected mice but less so in 263K prion-infected mice, whereas hydroxypropyl methylcellulose is effective in 263K prion-infected mice but less so in RML prion-infected mice. In the present study, we developed a combination therapy of cpd-B and hydroxypropyl methylcellulose expecting synergistic effects in both RML prion-infected mice and 263K prion-infected mice. A single subcutaneous administration of this combination had substantially a synergistic effect in RML prion-infected mice but had no additive effect in 263K prion-infected mice. These results showed that the effect of cpd-B was enhanced by hydroxypropyl methylcellulose. The complementary nature of the two compounds in efficacy against prion strains, chemical properties, pharmacokinetics, and physical properties appears to have contributed to the effective combination therapy. Our results pave the way for the strategy of new anti-prion agents.
► Our findings provide the first evidence of protein-bound polysaccharide K (PSK) as a new type of anti-prion compound. ► K PSK has anti-prion activity
in vitro and
in vivo. ► High molecular weight ...protein component(s) of PSK mainly cause anti-prion activity. ► PSK may be useful in elucidating the mechanism of prion replication.
Protein-bound polysaccharide K (PSK) is a clinical immunotherapeutic agent that exhibits various biological activities, including anti-tumor and anti-microbial effects. In the present study, we report on the anti-prion activity of PSK. It inhibited the formation of protease-resistant abnormal prion protein in prion-infected cells without any apparent alterations in either the normal prion protein turnover or the autophagic function in the cells. Its anti-prion activity was predominantly composed of the high molecular weight component(s) of the protein portion of PSK. A single subcutaneous dose of PSK slightly but significantly prolonged the survival time of peritoneally prion-infected mice, but PSK-treated mice produced neutralizing antibodies against the anti-prion activity of PSK. These findings suggest that PSK is a new anti-prion substance that may be useful in elucidating the mechanism of prion replication, although the structure of the anti-prion component(s) of PSK requires further evaluation.
Cultured cell lines infected with prions produce an abnormal isoform of the prion protein (PrPSc). In this study, two types of cells persistently infected with prion were treated with ...curcumin-related compounds. We found that the compounds behave differently in neuroblastoma neuro-2a (N2a) cells infected with different prion strains.
Curcumin and related compounds were applied to the two types of persistently prion infected cells to analyze the different activities of the compounds.
In ScN2a cells, which were infected with the Rocky Mountain Laboratory prion strain, two of the six compounds significantly reduced the PrPSc level in a dose-dependent manner. On the other hand, in N167 cells, effective suppression of the total amount of PrPSc was not observed; instead, two other compounds promoted the formation of covalently linked PrPSc dimers.
Chemometric analysis was used to determine the factors that contributed to the different effects of the six compounds. It showed that the ability to form hydrogen bonds, such as phenolic hydroxyl groups, and hydrophobic molecular properties predominantly contributed to the reduction of the PrPSc level in the ScN2a cells and the dimer formation of PrPSc in the N167 cells, respectively.
The extracted information can be used to delineate the differences among prion strains and to design compounds that are directed toward their respective activities.
Display omitted
•Two cells infected with different prion strains were treated with several compounds.•In one of the cells, the level of abnormal prion protein was reduced.•In the other cells, cross-linked dimer of abnormal prion protein was formed.•The different activities were explained with the characteristics of the compounds.•Preferable parameters for the respective activities of compounds were obtained.
Background
Alzheimer’s disease (AD) is an incurable neurodegenerative disease and the major cause of dementia. Recent studies including our findings showed that cellulose ethers (CEs) derivative ...(TC‐5RW) treatment as a single subcutaneous (SC) dose (4g/kg) have therapeutic effects in neurodegenerative diseases via inhibiting the aggregation of misfolded proteins such as prions and amyloid beta (Aβ). CEs are approved by the FDA as safe, inactive ingredients in foods and pharmaceuticals. Therefore, in this study we aimed to test whether single and repeated treatment with the CE TC‐5RW improves cognitive functions in an animal model of AD.
Methods
We used the 5xFAD mouse model, which harbours five familial AD mutations. The 5xFAD mice co‐overexpress human amyloid precursor protein and presenilin‐1, resulting in overproduction of Aβ and memory deficit. At the age of 6 weeks, one group of 5xFAD mice was treated with a single dose of TC‐5RW (4g/kg/SC) while another group of mice was treated weekly with TC‐5RW (4g/kg/SC) until 7 months of age. Two other groups of mice, wild type (WT) of same background and non‐treated 5xFAD mice were included as controls in our experiment. After completion of TC‐5RW treatment, behavioral studies (novel object recognition (NOR), Y‐maze and contextual fear conditioning (CFC) tests) were performed.
Results
In the NOR and Y‐maze tests, we observed a reduced percentage of recognition index and spontaneous alteration behavior in 5xFAD mice compared to WT mice. The TC‐5RW treatment at single and chronic dosage significantly increased the percentage of recognition index and spontaneous alteration behavior in 5xFAD mice compared to non‐treated 5xFAD mice. Similarly, the CFC test results showed a lower percentage of time freezing in 5xFAD mice compared to WT mice. Interestingly, TC‐5RW at both dosage regimen significantly improved the percentage of time freezing in 5xFAD mice compared to non‐treated 5xFAD mice.
Conclusion
In summary, single and chronic administration of TC‐5RW induce beneficial effects via improving learning and memory functions of 5xFAD mice. These results demonstrate that CE based compounds might be valuable and emerging therapeutics for the prevention and treatment of AD.
PDF
