Engineering Secretory Amyloids for Remote and Highly Selective Destruction of Metastatic Foci.

Functional amyloids produced in bacteria as nanoscale inclusion bodies are intriguing but poorly explored protein materials with wide therapeutic potential. Since they release functional polypeptides under physiological conditions, these materials can be potentially tailored as mimetic of secretory granules for slow systemic delivery of smart protein drugs. To explore this possibility, bacterial inclusion bodies formed by a self-assembled, tumor-targeted Pseudomonas exotoxin (PE24) are administered subcutaneously in mouse models of human metastatic colorectal cancer, for sustained secretion of tumor-targeted therapeutic nanoparticles. These proteins are functionalized with a peptidic ligand of CXCR4, a chemokine receptor overexpressed in metastatic cancer stem cells that confers high selective cytotoxicity in vitro and in vivo. In the mouse models of human colorectal cancer, time-deferred anticancer activity is detected after the subcutaneous deposition of 500 µg of PE24-based amyloids, which promotes a dramatic arrest of tumor growth in the absence of side toxicity. In addition, long-term prevention of lymphatic, hematogenous, and peritoneal metastases is achieved. These results reveal the biomedical potential and versatility of bacterial inclusion bodies as novel tunable secretory materials usable in delivery, and they also instruct how therapeutic proteins, even with high functional and structural complexity, can be packaged in this convenient format.

Ovalbumin self-assembles into amyloid nanosheets that elicit immune responses and facilitate sustained drug release.

Amyloids are associated with many neurodegenerative diseases, motivating investigations into their structure and function. Although not linked to a specific disease, albumins have been reported to form many structural aggregates. We were interested in investigating host immune responses to amyloid fibrils assembled from the model protein ovalbumin. Surprisingly, upon subjecting ovalbumin to standard denaturing conditions, we encountered giant protein nanosheets harboring amyloid-like features and hypothesized that these nanosheets might have potential in clinical or therapeutic applications. We found that the nanosheets, without the administration of any additional adjuvant, evoked a strong antibody response in mice that was higher than that observed for native ovalbumin. This suggests that amyloid nanosheets have a self-adjuvanting property. The nanosheet-induced immune response was helper T cell 2 (Th2) biased and negligibly inflammatory. While testing whether the nanosheets might form depots for the sustained release of precursor proteins, we did observe release of ovalbumin that mimicked the conformation of native protein. Moreover, the nanosheets could load the anticancer drug doxorubicin and release it in a slow and sustained manner. Taken together, our results suggest that amyloid nanosheets should be further investigated as either an antigen delivery vehicle or a multifunctional antigen and drug co-delivery system, with potential applications in simultaneous immunotherapy and chemotherapy.

α-Synuclein Amyloids Hijack Prion Protein to Gain Cell Entry, Facilitate Cell-to-Cell Spreading and Block Prion Replication.

The precise molecular mechanism of how misfolded α-synuclein (α-Syn) accumulates and spreads in synucleinopathies is still unknown. Here, we show the role of the cellular prion protein (PrPC) in mediating the uptake and the spread of recombinant α-Syn amyloids. The in vitro data revealed that the presence of PrPC fosters the higher uptake of α-Syn amyloid fibrils, which was also confirmed in vivo in wild type (Prnp +/+) compared to PrP knock-out (Prnp -/-) mice. Additionally, the presence of α-Syn amyloids blocked the replication of scrapie prions (PrPSc) in vitro and ex vivo, indicating a link between the two proteins. Indeed, whilst PrPC is mediating the internalization of α-Syn amyloids, PrPSc is not able to replicate in their presence. This observation has pathological relevance, since several reported case studies show that the accumulation of α-Syn amyloid deposits in Creutzfeldt-Jakob disease patients is accompanied by a longer disease course.

Spontaneous, Experimentally Induced, and Transmissible AA Amyloidosis in Japanese Quail ( Coturnix japonica).

The authors describe a spontaneous case of amyloid A (AA) amyloidosis in an adult female Japanese quail ( Coturnix japonica). The bird developed AA amyloidosis secondary to chronic peritonitis caused by a Gram-negative bacillus infection. Mild amyloid deposition was also identified in the intestinal tract of apparently healthy adult individuals, suggesting that quail may develop intestinal amyloidosis with age. Based on these observations, it was hypothesized that quail can develop AA amyloidosis following inflammatory stimulation with lipopolysaccharide (LPS). Therefore, adult quail were repeatedly injected with LPS and the development of AA amyloidosis was confirmed. The amyloid deposition in this model increased when quail amyloid was intravenously injected as an amyloid-enhancing factor. The experiments were repeated with young quail, but amyloid deposits were not observed following LPS injections. However, AA amyloidosis did develop when quail amyloid was injected in addition to LPS. These results indicated that adult quail develop AA amyloidosis after inflammatory stimulation with LPS. Furthermore, quail AA amyloidosis was shown to have transmissibility regardless of age. Interestingly, the authors found that administration of chicken amyloid fibrils also induced AA amyloidosis in young quail. This is the first report of cross-species transmission of avian AA amyloidosis.

Engineering tumor cell targeting in nanoscale amyloidal materials.

Bacterial inclusion bodies are non-toxic, mechanically stable and functional protein amyloids within the nanoscale size range that are able to naturally penetrate into mammalian cells, where they deliver the embedded protein in a functional form. The potential use of inclusion bodies in protein delivery or protein replacement therapies is strongly impaired by the absence of specificity in cell binding and penetration, thus preventing targeting. To address this issue, we have here explored whether the genetic fusion of two tumor-homing peptides, the CXCR4 ligands R9 and T22, to an inclusion body-forming green fluorescent protein (GFP), would keep the interaction potential and the functionality of the fused peptides and then confer CXCR4 specificity in cell binding and further uptake of the materials. The fusion proteins have been well produced in Escherichia coli in their full-length form, keeping the potential for fluorescence emission of the partner GFP. By using specific inhibitors of CXCR4 binding, we have demonstrated that the engineered protein particles are able to penetrate CXCR4+ cells, in a receptor-mediated way, without toxicity or visible cytopathic effects, proving the availability of the peptide ligands on the surface of inclusion bodies. Since no further modification is required upon their purification, the biological production of genetically targeted inclusion bodies opens a plethora of cost-effective possibilities in the tissue-specific intracellular transfer of functional proteins through the use of structurally and functionally tailored soft materials.

Two alternative pathways for generating transmissible prion disease de novo.

INTRODUCTION: Previous studies established that prion disease with unique strain-specific phenotypes could be induced by in vitro-formed recombinant PrP (rPrP) fibrils with structures different from that of authentic prions, or PrP(Sc). To explain the etiology of prion diseases, new mechanism proposed that in animals the transition from rPrP fibrils to PrP(Sc) consists of two main steps: the first involves fibril-induced formation of atypical PrPres, a self-replicating but clinically silent state, and the second consists of atypical PrPres-dependent formation of PrP(Sc) via rare deformed templating events. RESULTS: In the current study, atypical PrPres with characteristics similar to those of brain-derived atypical PrPres was generated in vitro. Upon inoculation into animals, in vitro-generated atypical PrPres gave rise to PrP(Sc) and prion disease with a phenotype similar to those induced by rPrP fibrils. Significant differences in the sialylation pattern between atypical PrPres and PrP(Sc) suggested that only a small sub-fraction of the PrP(C) that is acceptable as a substrate for PrP(Sc) could be also recruited by atypical PrPres. This can explain why atypical PrPres replicates slower than PrP(Sc) and why PrP(Sc) outcompetes atypical PrPres. CONCLUSIONS: This study illustrates that transmissible prion diseases with very similar disease phenotypes could be produced via two alternative procedures: direct inoculation of recombinant PrP amyloid fibrils or in vitro-produced atypical PrPres. Moreover, this work showed that preparations of atypical PrPres free of PrP(Sc) can give rise to transmissible diseases in wild type animals and that atypical PrPres generated in vitro is an adequate model for brain-derived atypical PrPres.

Amiloidosis traqueobronquial: diagnóstico, tratamiento y evolución en 5 casos / Tracheobronchial amyloidosis: Diagnosis, treatment and evolution in 5 patients

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Noradrenergic and serotonergic neurochemistry arising from intranasal inoculation with α-synuclein aggregates which incite parkinsonian-like symptoms.

Alpha-synuclein (α-syn) toxic aggregates delivered by the nasal vector have been shown to modify the neurochemistry of dopamine (DA) which is associated with parkinsonian-like motor symptoms. The aim was therefore to study the intranasal effects of α-syn oligomers, fibrils or their combination on the motor behavior of aged mice in relation to possible noradrenergic and serotonergic correlates. In vitro generated α-syn oligomers and fibrils were verified using atomic force microscopy and the thioflavin T binding assay. Levels of noradrenaline (NA), serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) were detected using HPLC with electrochemical detection in the substantia nigra (SN) and striatum. The oligomers or fibrils administered alone or in a 50:50 combination (total dose of 0.48 mg/kg) were given intranasally for 14 days and "open-field" behaviour was tested on days 0, 15 and 28 of the protocol, at which time brain structures were sampled. Behavioral deficits at the end of the 14-day dosing regime and on day 28 (i.e. 14 days after treatment completion) induced hypokinesia and immobility whilst the aggregate combination additionally produced rigidity. The α-Syn oligomer/fibril mixture also instigated PD-like motor symptoms which correlated heterochronically with elevated NA levels in the striatum but then later in the SN while intranasal fibrils alone augmented 5-HT and 5-HIAA nigral concentrations throughout the protocol. In contrast, α-syn oligomers displayed a delayed serotonin upsurge in the SN. Neurodegenerative and/or actions on neurotransmitter transporters (such as NET, SERT and VMAT2) are discussed as being implicated in these α-syn amyloid induced neurochemical and motoric disturbances.

Ultrasonication-dependent formation and degradation of α-synuclein amyloid fibrils.

Ultrasonication can be used to break the supersaturation of α-synuclein, a protein associated with Parkinson's disease, at pH7.4 above the critical concentration of fibrillation, thereby inducing the formation of amyloid fibrils. We speculated that ultrasonication could also be used to depolymerize preformed fibrils below the critical concentration. However, extensive ultrasonic irradiation transformed preformed fibrils into amorphous aggregates even above the critical concentration. Exposing preformed fibrils to the hydrophobic air-water interface of cavitation bubbles may have destabilized the fibrils and stabilized amorphous aggregates. Upon extensive ultrasonic irradiation, the accompanying decomposition of chemical structures was suggested when monitored by analytical ultracentrifugation. Amorphous aggregates produced by extensive ultrasonication showed higher cytotoxicity, suggesting that, although ultrasonication might be a useful approach for inactivating amyloid fibrils, potential cytotoxicity of amorphous aggregates should be considered.

Failure of heterogeneous amyloid-enhancing factor in geriatric squirrel monkeys (Saimiri boliviensis).

BACKGROUND: Cross-species transmission of AA amyloidosis between primates and other animals has not been previously reported. METHODS: Eight geriatric squirrel monkeys were intravenously administered chimpanzee, bovine, or chicken amyloid fibrils and simultaneously received inflammatory stimulation. RESULTS: AA amyloid deposition was not detected in any of the monkeys histopathologically or immunohistochemically. CONCLUSIONS: These results suggest that heterogeneous AA amyloidosis may not be easily transmitted into primates.

Intranasal administration of alpha-synuclein aggregates: a Parkinson's disease model with behavioral and neurochemical correlates.

Parkinson's disease (PD) is a neurodegenerative disorder in which both alpha-synuclein (α-syn) and dopamine (DA) have a critical role. Our previous studies instigated a novel PD model based on nasal inoculation with α-syn aggregates which expressed parkinsonian-like behavioral and immunological features. The current study in mice substantiated the robustness of the amyloid nasal vector model by examining behavioral consequences with respect to DA-ergic neurochemical corollaries. In vitro generated α-syn oligomers and fibrils were characterized using atomic force microscopy and the thioflavin T binding assay. These toxic oligomers or fibrils administered alone (0.48 mg/kg) or their 50:50 combination (total dose of 0.48 mg/kg) were given intranasally for 14 days and "open-field" behavior was tested on days 0, 15 and 28 of the protocol. Behavioral deficits at the end of the 14-day dosing regime and on day 28 (i.e., 14 days after treatment completion) induced rigidity, hypokinesia and immobility. This was accompanied by elevated nigral but not striatal DA, DOPAC and HVA concentrations in response to dual administration of α-syn oligomers plus fibrils but not the oligomers by themselves. α-Syn fibrils intensified not only the hypokinesia and immobility 14 days post treatment, but also reduced vertical rearing and enhanced DA levels in the substantia nigra. Only nigral DA turnover (DOPAC/DA but not HVA/DA ratio) was augmented in response to fibril treatment but there were no changes in the striatum. Compilation of these novel behavioral and neurochemical findings substantiate the validity of the α-syn nasal vector model for investigating parkinsonian-like symptoms.

Experimental induction and oral transmission of avian AA amyloidosis in vaccinated white hens.

Avian AA amyloidosis is commonly observed in adult birds afflicted with bacterial infections or chronic inflammatory disorders. Experimental AA amyloidosis in birds can be induced by repeated inflammatory stimulation, such as injection with casein or vaccination with oil-emulsified bacterins. However, the transmission of amyloidosis among avian species has not been studied well to date. In the present study, we confirm the potential induction of avian AA amyloidosis by inoculation of Salmonella enteritidis (SE) vaccine or Mycoplasma gallisepticum vaccine. To determine the transmission of chicken AA amyloidosis among white hens, we induced experimental AA amyloidosis in vaccinated chickens by intravenous or oral administration of chicken AA fibrils. Amyloid deposits were observed in chickens injected with SE and inoculated with chicken AA fibrils intravenously (21/26: 81%) and orally (8/12: 67%). These results suggest that chicken AA amyloidosis can be induced by vaccinations, and may be transmitted among like species by oral administration.

Intracerebral inoculation of pathological α-synuclein initiates a rapidly progressive neurodegenerative α-synucleinopathy in mice.

The accumulation of misfolded proteins is a fundamental pathogenic process in neurodegenerative diseases. However, the factors that trigger aggregation of α-Synuclein (α-Syn), the principal component of the intraneuronal inclusions known as Lewy bodies (LBs), and Lewy neurites (LNs), which characterize Parkinson's disease (PD) and dementia with LBs (DLB), are poorly understood. We show here that in young asymptomatic α-Syn transgenic (Tg) mice, intracerebral injections of brain homogenates derived from older Tg mice exhibiting α-Syn pathology accelerate both the formation of intracellular LB/LN-like inclusions and the onset of neurological symptoms in recipient animals. Pathological α-Syn propagated along major central nervous system (CNS) pathways to regions far beyond injection sites and reduced survival with a highly reproducible interval from injection to death in inoculated animals. Importantly, inoculation with α-Syn amyloid fibrils assembled from recombinant human α-Syn induced identical consequences. Furthermore, we show for the first time that synthetic α-Syn fibrils are wholly sufficient to initiate PD-like LBs/LNs and to transmit disease in vivo. Thus, our data point to a prion-like cascade in synucleinopathies whereby cell-cell transmission and propagation of misfolded α-Syn underlie the CNS spread of LBs/LNs. These findings open up new avenues for understanding the progression of PD and for developing novel therapeutics.

Characterisation of amyloid-induced inflammatory responses in the rat retina.

Amyloid-induced inflammation is thought to play a critical and early role in the pathophysiology of Alzheimer's disease. As such, robust models with relevant and accessible compartments that provide a means of assessing anti-inflammatory agents are essential for the development of therapeutic agents. In the present work, we have characterised the induction of inflammation in the rat retina following intravitreal administration of amyloid-beta protein (Aß). Histology and mRNA endpoints in the retina demonstrate Aß1-42-, but not Aß42-1-, induced inflammatory responses characterised by increases in markers for microglia and astrocytes (ionised calcium-binding adaptor molecule 1 (iba-1), GFAP and nestin) and increases in mRNA for inflammatory cytokines and chemokines such as IL1-ß, MIP1α and TNFα. Likewise, analysis of vitreal cytokines also revealed increases in inflammatory cytokines and chemokines, including IL1-ß, MIP1α and MCP1, induced by Aß1-42 but not Aß42-1. This profile of pro-inflammatory gene and protein expression is consistent with that observed in the Alzheimer's disease brain and suggest that this preclinical model may provide a useful relevant tool in the development of anti-inflammatory approaches directed towards Alzheimer's disease therapy.

Noradrenergic neurons of the area postrema mediate amylin's hypophagic action.

Circulating amylin inhibits food intake via activation of the area postrema (AP). The aim of this study was to identify the neurochemical phenotype of the neurons mediating amylin's hypophagic action by immunohistochemical and feeding studies in rats. Expression of c-Fos protein was used as a marker for neuronal activation and dopamine-beta-hydroxylase (DBH), the enzyme-catalyzing noradrenaline synthesis, as a marker for noradrenergic neurons. We found that approximately 50% of amylin-activated AP neurons are noradrenergic. To clarify the functional role of these neurons in amylin's effect on eating, noradrenaline-containing neurons in the AP were lesioned using a saporin conjugated to an antibody against DBH. Amylin (5 or 20 microg/kg s.c.)-induced anorexia was observed in sham-lesioned rats with both amylin doses. Rats with a lesion of > 50% of the noradrenaline neurons were unresponsive to the low dose of amylin (5 microg/kg) and only displayed a reduction in food intake 60 min after injection of the high amylin dose (20 microg/kg). In a terminal experiment, the same rats received amylin (20 microg/kg) or saline. The AP and nucleus of the solitary tract (NTS) were stained for DBH to assess noradrenaline lesion success and for c-Fos expression to evaluate amylin-induced neuronal activation. In contrast to sham-lesioned animals, noradrenaline-lesioned rats did not show a significant increase in amylin-induced c-Fos expression in the AP and NTS. We conclude that the noradrenergic neurons in the AP mediate at least part of amylin's hypophagic effect.

Central amylin acts as an adiposity signal to control body weight and energy expenditure.

The pancreatic B-cell hormone amylin has been proposed to be both a satiation signal and an adiposity signal. The effects of peripheral amylin on energy balance are well investigated, but the effects of central amylin are less clear. We determined the effects of low doses of amylin administered into the 3rd cerebral ventricle (i3vt) on food intake, body weight and other indices of energy balance. Amylin (2 pmol/h) significantly lowered body weight compared to saline after 2 weeks of infusion, independent of whether prior body weight was decreased by fasting, increased by voluntary overfeeding or unmanipulated. A bolus injection of amylin (10 pmol, i3vt) increased energy expenditure and body temperature, whereas chronic i3vt amylin infusion had no effect on energy expenditure above that of control rats even though body temperature was increased. Chronic amylin also reduced RQ, implying a preferential oxidation of fat. Overall, the data provide new evidence that amylin is an adiposity signal that acts within the brain, and informing the brain about the status of peripheral energy stores.

Comparison of the post-meal glucose response to different insulin bolus waveforms in insulin pump- and pre-meal pramlintide-treated type 1 diabetes patients.

BACKGROUND: Both pramlintide and insulin pump waveforms separately provide improved post-meal glucose control. However, when used together there may be a mismatch in actions leading to hypoglycemia. We studied the three currently available waveforms and a "modified combination wave" (MC) in pramlintide-treated patients. The MC was a "square" (SQ) wave combined with a "standard" (ST) bolus that was delayed 1 h into the mealtime. METHODS: Using the CGMS Gold (Medtronics, Northridge, CA) we measured the glucose response 0-4 h after the beginning of a meal and 15 min after the initiation of the insulin bolus wave and pramlintide (60 microg), bolus. Pump-treated type 1 diabetes subjects were randomized to one bolus waveform for one full day of three meals and then crossed over to the other bolus waveforms. In the first study nine subjects were randomized to the ST, SQ, or "combination" (C) wave consisting of a ST wave at the beginning of a SQ wave. In the second study nine subjects were randomized to SQ or MC. RESULTS: With ST and C waves glucose fell approximately 40 mg/dL 0-2 h post-meal and then returned to baseline by the fourth hour. Initially isoglycemic, the SQ wave increased approximately 20 mg/dL in the late meal period. The MC demonstrated minimal (approximately 10 mg/dL) change during the entire post-meal period. CONCLUSIONS: For currently available insulin pump bolus waves, SQ and MC may be least likely to cause hypoglycemia in pramlintide-treated patients.