Differential overexpression of SERPINA3 in human prion diseases

Diagnostic and therapeutic value of human serpin family proteins

SERPIN (serine proteinase inhibitors) is an acronym for the superfamily of structurally similar proteins found in animals, plants, bacteria, viruses, and archaea. Over 1500 SERPINs are known in nature, while only 37 SERPINs are found in humans, which participate in inflammation, coagulation, angiogenesis, cell viability, and other pathophysiological processes. Both qualitative or quantitative deficiencies or overexpression and/or abnormal accumulation of SERPIN can lead to diseases commonly referred to as "serpinopathies". Hence, strategies involving SERPIN supplementation, elimination, or correction are utilized and/or under consideration. In this review, we discuss relationships between certain SERPINs and diseases as well as putative strategies for the clinical explorations of SERPINs.

Transcriptomics of a cytoglobin knockout mouse: Insights from hepatic stellate cells and brain

The vertebrate respiratory protein cytoglobin (Cygb) is thought to exert multiple cellular functions. Here we studied the phenotypic effects of a Cygb knockout (KO) in mouse on the transcriptome level. RNA sequencing (RNA-Seq) was performed for the first time on sites of major endogenous Cygb expression, i.e. quiescent and activated hepatic stellate cells (HSCs) and two brain regions, hippocampus and hypothalamus. The data recapitulated the up-regulation of Cygb during HSC activation and its expression in the brain. Differential gene expression analyses suggested a role of Cygb in the response to inflammation in HSCs and its involvement in retinoid metabolism, retinoid X receptor (RXR) activation-induced xenobiotics metabolism, and RXR activation-induced lipid metabolism and signaling in activated cells. Unexpectedly, only minor effects of the Cygb KO were detected in the transcriptional profiles in hippocampus and hypothalamus, precluding any enrichment analyses. Furthermore, the transcriptome data pointed at a previously undescribed potential of the Cygb- knockout allele to produce cis-acting effects, necessitating future verification studies.

Cholesterol 24-hydroxylase at the choroid plexus contributes to brain immune homeostasis

The choroid plexus (CP) plays a key role in remotely controlling brain function in health, aging, and disease. Here, we report that CP epithelial cells express the brain-specific cholesterol 24-hydroxylase (CYP46A1) and that its levels are decreased under different mouse and human brain conditions, including amyloidosis, aging, and SARS-CoV-2 infection. Using primary mouse CP cell cultures, we demonstrate that the enzymatic product of CYP46A1, 24(S)-hydroxycholesterol, downregulates inflammatory transcriptomic signatures within the CP, found here to be elevated across multiple neurological conditions. In vitro, the pro-inflammatory cytokine tumor necrosis factor α (TNF-α) downregulates CYP46A1 expression, while overexpression of CYP46A1 or its pharmacological activation in mouse CP organ cultures increases resilience to TNF-α. In vivo, overexpression of CYP46A1 in the CP in transgenic mice with amyloidosis is associated with better cognitive performance and decreased brain inflammation. Our findings suggest that CYP46A1 expression in the CP impacts the role of this niche as a guardian of brain immune homeostasis.

Integrated analysis of robust sex-biased gene signatures in human brain

BACKGROUND

Sexual dimorphism is highly prominent in mammals with many physiological and behavioral differences between male and female form of the species. Accordingly, the fundamental social and cultural stratification factors for humans is sex. The sex differences are thought to emerge from a combination of genetic and environmental factors. It distinguishes individuals most prominently on the reproductive traits, but also affects many of the other related traits and manifest in different disease susceptibilities and treatment responses across sexes. Sex differences in brain have raised a lot of controversy due to small and sometimes contradictory sex-specific effects. Many studies have been published to identify sex-biased genes in one or several brain regions, but the assessment of the robustness of these studies is missing. We therefore collected huge amount of publicly available transcriptomic data to first estimate whether consistent sex differences exist and further explore their likely origin and functional significance.

RESULTS AND CONCLUSION

In order to systematically characterise sex-specific differences across human brain regions, we collected transcription profiles for more than 16,000 samples from 46 datasets across 11 brain regions. By systematic integration of the data from multiple studies, we identified robust transcription level differences in human brain across to identify male-biased and female-biased genes in each brain region. Firstly, both male and female-biased genes were highly conserved across primates and showed a high overlap with sex-biased genes in other species. Female-biased genes were enriched for neuron-associated processes while male-biased genes were enriched for membranes and nuclear structures. Male-biased genes were enriched on the Y chromosome while female-biased genes were enriched on the X chromosome, which included X chromosome inactivation escapees explaining the origins of some sex differences. Male-biased genes were enriched for mitotic processes while female-biased genes were enriched for synaptic membrane and lumen. Finally, sex-biased genes were enriched for drug-targets and more female-biased genes were affected by adverse drug reactions than male-biased genes. In summary, by building a comprehensive resource of sex differences across human brain regions at gene expression level, we explored their likely origin and functional significance. We have also developed a web resource to make the entire analysis available for the scientific community for further exploration, available at https://joshiapps.cbu.uib.no/SRB_app/.

Strain-Dependent Morphology of Reactive Astrocytes in Human- and Animal-Vole-Adapted Prions

Reactive astrogliosis is one of the pathological hallmarks of prion diseases. Recent studies highlighted the influence of several factors on the astrocyte phenotype in prion diseases, including the brain region involved, the genotype backgrounds of the host, and the prion strain. Elucidating the influence of prion strains on the astrocyte phenotype may provide crucial insights for developing therapeutic strategies. Here, we investigated the relationship between prion strains and astrocyte phenotype in six human- and animal-vole-adapted strains characterized by distinctive neuropathological features. In particular, we compared astrocyte morphology and astrocyte-associated PrP^Sc deposition among strains in the same brain region, the mediodorsal thalamic nucleus (MDTN). Astrogliosis was detected to some extent in the MDTN of all analyzed voles. However, we observed variability in the morphological appearance of astrocytes depending on the strain. Astrocytes displayed variability in thickness and length of cellular processes and cellular body size, suggesting strain-specific phenotypes of reactive astrocytes. Remarkably, four out of six strains displayed astrocyte-associated PrP^Sc deposition, which correlated with the size of astrocytes. Overall, these data show that the heterogeneous reactivity of astrocytes in prion diseases depends at least in part on the infecting prion strains and their specific interaction with astrocytes.

Urinary proteome profiles associated with cognitive decline in community elderly residents—A pilot study

Non-invasive and simple methods enabling easy identification of individuals at high risk of cognitive decline are needed as preventive measures against dementia. This pilot study aimed to explore protein biomarkers that can predict cognitive decline using urine, which can be collected non-invasively. Study subjects were selected from participants in a cohort study of middle-aged and older community-dwelling adults who underwent cognitive testing using the Mini-Mental State Examination and provided spot urine samples at two time points with an interval of approximately 5 years. Seven participants whose cognitive function declined 4 or more points from baseline (Group D) and 7 sex- and age-matched participants whose cognitive function remained within the normal range during the same period (Group M) were selected. Urinary proteomics using mass spectrometry was performed and discriminant models were created using orthogonal partial least squares-discriminant analysis (OPLS-DA). OPLS-DA yielded two models that significantly discriminated between the two groups at baseline and follow-up. Both models had ORM1, ORM2, and SERPINA3 in common. A further OPLS-DA model using baseline ORM1, ORM2, and SERPINA3 data showed similar predictive performance for data at follow-up as it did for baseline data (sensitivity: 0.85, specificity: 0.85), with the receiver operating characteristic curve analysis yielding an area under the curve of 0.878. This prospective study demonstrated the potential for using urine to identify biomarkers of cognitive decline.

SERPINA3: Stimulator or Inhibitor of Pathological Changes

SERPINA3, also called α-1-antichymotrypsin (AACT, ACT), is one of the inhibitors of serine proteases, one of which is cathepsin G. As an acute-phase protein secreted into the plasma by liver cells, it plays an important role in the anti-inflammatory response and antiviral response. Elevated levels of SERPINA3 have been observed in heart failure and neurological diseases such as Alzheimer's disease or Creutzfeldt-Jakob disease. Many studies have shown increased expression levels of the SERPINA3 gene in various types of cancer, such as glioblastoma, colorectal cancer, endometrial cancer, breast cancer, or melanoma. In this case, the SERPINA3 protein is associated with an antiapoptotic function implemented by adjusting the PI3K/AKT or MAPK/ERK 1/2 signal pathways. However, the functions of the SERPINA3 protein are still only partially understood, mainly in the context of cancerogenesis, so it seems necessary to summarize the available information and describe its mechanism of action. In particular, we sought to amass the existing body of research focusing on the description of the underlying mechanisms of various diseases not related to cancer. Our goal was to present an overview of the correct function of SERPINA3 as part of the defense system, which unfortunately easily becomes the "Fifth Column" and begins to support processes of destruction.

Urinary serpin-A3 is an early predictor of clinical response to therapy in patients with proliferative lupus nephritis

We have previously reported that urinary excretion of serpin-A3 (uSerpA3) is significantly elevated in patients with active lupus nephritis (LN). Here, we evaluated the course of uSerpA3 during the first year of treatment and its association with response to therapy in patients with proliferative LN. The observational longitudinal study included 60 Mexican adults with proliferative LN followed during the first year after LN flare. uSerpA3 was detected by Western blot analysis at flare and after 3, 6, and 12 mo. The response to therapy was determined 1 yr after the LN flare. We evaluated the correlation between uSerpA3 and histological parameters at LN flare. The temporal association between uSerpA3 and response to therapy was analyzed with linear mixed models. uSerpA3 prognostic performance for response was evaluated with receiver-operating characteristic curves. Among the 60 patients studied, 21 patients (35%) were class III and 39 patients (65%) were class IV. uSerpA3 was higher in class IV than in class III LN (6.98 vs. 2.89 dots per in./mg creatinine, P = 0.01). Furthermore, uSerpA3 correlated with the histological activity index (r = 0.29, P = 0.02). There was a significant association between the temporal course of uSerpA3 and response to therapy. Responders showed a significant drop in uSerpA3 at 6 mo compared with LN flare (P < 0.001), whereas nonresponders persisted with elevated uSerpA3. Moreover, uSerpA3 was significantly lower at flare in responders compared with nonresponders (2.69 vs. 6.98 dots per in./mg creatinine, P < 0.05). Furthermore, uSerpA3 was able to identify nonresponders since 3 mo after LN flare (area under the curve: 0.77). In conclusion, uSerpA3 is an early indicator of kidney inflammation and predictor of the clinical response to therapy in patients with proliferative LN.NEW & NOTEWORTHY LN requires aggressive immunosuppression to improve long-term outcomes. Current indicators of remission take several months to normalize, prolonging treatment regiments in some cases. Serpin-A3 is present in urine of patients with proliferative LN. We evaluated the excretion of serpin-A3 in serial samples of patients with proliferative LN during the first year after flare. We found that uSerpA3 correlates with kidney inflammation and its decline at early points predicts the response to therapy 1 yr after flare.

Distinct translatome changes in specific neural populations precede electroencephalographic changes in prion-infected mice

Selective vulnerability is an enigmatic feature of neurodegenerative diseases (NDs), whereby a widely expressed protein causes lesions in specific cell types and brain regions. Using the RiboTag method in mice, translational responses of five neural subtypes to acquired prion disease (PrD) were measured. Pre-onset and disease onset timepoints were chosen based on longitudinal electroencephalography (EEG) that revealed a gradual increase in theta power between 10- and 18-weeks after prion injection, resembling a clinical feature of human PrD. At disease onset, marked by significantly increased theta power and histopathological lesions, mice had pronounced translatome changes in all five cell types despite appearing normal. Remarkably, at a pre-onset stage, prior to EEG and neuropathological changes, we found that 1) translatomes of astrocytes indicated reduced synthesis of ribosomal and mitochondrial components, 2) glutamatergic neurons showed increased expression of cytoskeletal genes, and 3) GABAergic neurons revealed reduced expression of circadian rhythm genes. These data demonstrate that early translatome responses to neurodegeneration emerge prior to conventional markers of disease and are cell type-specific. Therapeutic strategies may need to target multiple pathways in specific populations of cells, early in disease.

Prions are infectious agents composed of a misfolded protein. When isolated from a mammalian brain and transferred to the same host species, prions will cause the same neurodegenerative disease affecting the same brain regions and cell types. This concept of selective vulnerability is also a feature of more common types of neurodegenerative diseases, such as Alzheimer’s, Parkinson’s, and Huntington’s. To better understand the mechanisms behind selective vulnerability, we studied disease responses of five cell types with different vulnerabilities in prion-infected mice at two different disease stages. Responses were measured as changes to mRNAs undergoing translation, referred to as the translatome. Before prion-infected mice demonstrated typical disease signs, electroencephalography (a method used clinically to characterize neurodegeneration in humans) revealed brain changes resembling those in human prion diseases, and surprisingly, the translatomes of all cells were drastically changed. Furthermore, before electroencephalography changes emerged, three cell types made unique responses while the most vulnerable cell type did not. These results suggests that mechanisms causing selective vulnerability will be difficult to dissect and that therapies will likely need to be provided before clinical signs emerge and individually engage multiple cell types and their distinct molecular pathways.

Explaining a series of models by propagating Shapley values

Local feature attribution methods are increasingly used to explain complex machine learning models. However, current methods are limited because they are extremely expensive to compute or are not capable of explaining a distributed series of models where each model is owned by a separate institution. The latter is particularly important because it often arises in finance where explanations are mandated. Here, we present Generalized DeepSHAP (G-DeepSHAP), a tractable method to propagate local feature attributions through complex series of models based on a connection to the Shapley value. We evaluate G-DeepSHAP across biological, health, and financial datasets to show that it provides equally salient explanations an order of magnitude faster than existing model-agnostic attribution techniques and demonstrate its use in an important distributed series of models setting.

Innovative Non-PrP-Targeted Drug Strategy Designed to Enhance Prion Clearance

Prion diseases are a group of neurodegenerative disorders characterized by the accumulation of misfolded prion protein (called PrP^Sc). Although conversion of the cellular prion protein (PrP^C) to PrP^Sc is still not completely understood, most of the therapies developed until now are based on blocking this process. Here, we propose a new drug strategy aimed at clearing prions without any direct interaction with neither PrP^C nor PrP^Sc. Starting from the recent discovery of SERPINA3/SerpinA3n upregulation during prion diseases, we have identified a small molecule, named compound 5 (ARN1468), inhibiting the function of these serpins and effectively reducing prion load in chronically infected cells. Although the low bioavailability of this compound does not allow in vivo studies in prion-infected mice, our strategy emerges as a novel and effective approach to the treatment of prion disease.

Serpin Signatures in Prion and Alzheimer's Diseases

Serpins represent the most broadly distributed superfamily of proteases inhibitors. They contribute to a variety of physiological functions and any alteration of the serpin-protease equilibrium can lead to severe consequences. SERPINA3 dysregulation has been associated with Alzheimer's disease (AD) and prion diseases. In this study, we investigated the differential expression of serpin superfamily members in neurodegenerative diseases. SERPIN expression was analyzed in human frontal cortex samples from cases of sporadic Creutzfeldt-Jakob disease (sCJD), patients at early stages of AD-related pathology, and age-matched controls not affected by neurodegenerative disorders. In addition, we studied whether Serpin expression was dysregulated in two animal models of prion disease and AD.Our analysis revealed that, besides the already observed upregulation of SERPINA3 in patients with prion disease and AD, SERPINB1, SERPINB6, SERPING1, SERPINH1, and SERPINI1 were dysregulated in sCJD individuals compared to controls, while only SERPINB1 was upregulated in AD patients. Furthermore, we analyzed whether other serpin members were differentially expressed in prion-infected mice compared to controls and, together with SerpinA3n, SerpinF2 increased levels were observed. Interestingly, SerpinA3n transcript and protein were upregulated in a mouse model of AD. The SERPINA3/SerpinA3nincreased anti-protease activity found in post-mortem brain tissue of AD and prion disease samples suggest its involvement in the neurodegenerative processes. A SERPINA3/SerpinA3n role in neurodegenerative disease-related protein aggregation was further corroborated by in vitro SerpinA3n-dependent prion accumulation changes. Our results indicate SERPINA3/SerpinA3n is a potential therapeutic target for the treatment of prion and prion-like neurodegenerative diseases.

Gene expression and epigenetic markers of prion diseases

Epigenetics, meaning the variety of mechanisms underpinning gene regulation and chromatin states, plays a key role in normal development as well as in disease initiation and progression. Epigenetic mechanisms like alteration of DNA methylation, histone modifications, and non-coding RNAs, have been proposed as biomarkers for diagnosis, classification, or monitoring of responsiveness to treatment in many diseases. In prion diseases, the profound associations with human aging, the effects of cell type and differentiation on in vitro susceptibility, and recently identified human risk factors, all implicate causal epigenetic mechanisms. Here, we review the current state of the art of epigenetics in prion diseases and its interaction with genetic determinants. In particular, we will review recent advances made by several groups in the field profiling DNA methylation and microRNA expression in mammalian prion diseases and the potential for these discoveries to be exploited as biomarkers.

Novel Exosome Biomarker Candidates for Alzheimer's Disease Unravelled Through Mass Spectrometry Analysis

Exosomes are small extracellular vesicles (EVs) present in human biofluids that can transport specific disease-associated molecules. Consequently blood-derived exosomes have emerged as important peripheral biomarker sources for a wide range of diseases, among them Alzheimer’s disease (AD). Although there is no effective cure for AD, an accurate diagnosis, relying on easily accessible peripheral biofluids, is still necessary to discriminate this disease from other dementias, test potential therapies and even monitor rate of disease progression. The ultimate goal is to produce a cost-effective and widely available alternative, which can also be employed as a first clinical screen. In this study, EVs with exosome-like characteristics were isolated from serum of Controls and AD cases through precipitation- and column-based methods, followed by mass spectrometry analysis. The resulting proteomes were characterized by Gene Ontology (GO) and multivariate analyses. Although GO terms were similar for exosomes’ proteomes of Controls and ADs, using both methodologies, a clear segregation of disease cases was obtained when using the precipitation-based method. Nine significantly different abundant proteins were identified between Controls and AD cases, representing putative biomarker candidate targets. Among them are AACT and C4BPα, two Aβ-binding proteins, whose exosome levels were further validated in individuals from independent cohorts using antibody-based approaches. The findings discussed represent an important contribution to the identification of novel exosomal biomarker candidates useful as potential blood-based tools for AD diagnosis.

Association of α-1-Antichymotrypsin Expression with the Development of Conformational Changes of Tau Protein in Alzheimer's Disease Brain

In Alzheimer's disease (AD), two mutually exclusive amino-terminal-dependent conformations have been reported to occur during the aggregation of Tau protein into neurofibrillary tangles (NFTs). An early conformation of full-length Tau, involving the bending of the amino terminus over the third repeated domain, is recognized by the Alz-50 antibody, followed by a second conformation recognized by Tau-66 antibody that depends on the folding of the proline-rich region over the third repeated domain in a molecule partially truncated at the amino- and carboxyl-termini. α-1-antichymotrypsin (ACT) is an acute phase serum glycoprotein that accumulates abnormally in the brain of AD patients, and since it is considered to promote the in vitro and in vivo aggregation of amyloid-β, we here seek further evidence that ACT may also contribute to the abnormal aggregation of Tau in AD. By analyzing brain samples from a population of AD cases under immunofluorescence and high-resolution confocal microscopy, we demonstrate here the abundant expression of ACT in hippocampal neurons, visualized as a granular diffuse accumulation, frequently reaching the nuclear compartment. In a significant number of these neurons, intracellular NFTs composed of abnormally phosphorylated and truncated Tau at Asp⁴²¹ were also observed to coexist in separated regions of the cytoplasm. However, we found strong colocalization between ACT and diffuse aggregates of Tau-66-positive granules, which was not observed with Alz-50 antibody. These results suggest that ACT may play a role during the development of Tau conformational changes facilitating its aggregation during the formation of the neurofibrillary pathology in AD.

Circulating SERPINA3 improves prognostic stratification in patients with a de novo or worsened heart failure

Aims

We investigated the prognostic relevance of serpin peptidase inhibitor, clade A member 3 (SERPINA3) in patients admitted with a de novo or worsened heart failure (HF).

Methods and results

In the first stage, 83 HF‐related left ventricular (LV) transcripts were examined in patients with congestive cardiomyopathy (CCMP, n = 44) who died within 5 years and compared with age‐matched and haemodynamically matched CCMP survivors (n = 39) and controls with normal LV function (n = 17). Among 14 differentially expressed transcripts, myocardial gene and circulating SERPINA3 levels were up‐regulated in non‐survivors vs. survivors (2.40 ± 3.66 vs. 0.36 ± 0.22 units, P < 0.01 and 334.7 ± 138.7 vs. 228.2 ± 83.1 μg/mL, P < 0.01, respectively). While no significant transmyocardial gradient was detected, cytokine stimulation of human endothelial cells induced SERPINA3 secretion. In an independent validation cohort with a de novo or worsened HF (n = 387), circulating SERPINA3 levels > 316 μg/mL were associated with increased all‐cause mortality {hazard ratio [HR] [95% confidence interval (CI)]: 2.4 [1.5–3.9], P = 0.0002} and its composite with unplanned cardiovascular readmission [HR (95% CI): 2.0 (1.2–3.3), P = 0.004]. Patients with elevated SERPINA3 levels and elevated either N‐terminal pro brain natriuretic peptide or ST2 showed worse freedom from both endpoints. In a multivariate analysis, including established clinical risk factors, SERPINA3 remained independent predictor of all‐cause mortality together with age, gender, ST2, glomerular filtration, and pulmonary capillary wedge pressure.

Conclusion

In patients with a de novo or worsened HF, increased SERPINA3 levels > 316 μg/mL are associated with increased mortality or unplanned cardiac readmission. Elevated SERPINA3 levels on top of established clinical predictors appear to identify a subgroup of HF patients at higher mortality risk. Prospective studies should further validate its value in prognostic stratification of HF.

Identification and drug-induced reversion of molecular signatures of Alzheimer's disease onset and progression in AppNL-G-F, AppNL-F, and 3xTg-AD mouse models

BACKGROUND

In spite of many years of research, our understanding of the molecular bases of Alzheimer's disease (AD) is still incomplete, and the medical treatments available mainly target the disease symptoms and are hardly effective. Indeed, the modulation of a single target (e.g., β-secretase) has proven to be insufficient to significantly alter the physiopathology of the disease, and we should therefore move from gene-centric to systemic therapeutic strategies, where AD-related changes are modulated globally.

METHODS

Here we present the complete characterization of three murine models of AD at different stages of the disease (i.e., onset, progression and advanced). We combined the cognitive assessment of these mice with histological analyses and full transcriptional and protein quantification profiling of the hippocampus. Additionally, we derived specific Aβ-related molecular AD signatures and looked for drugs able to globally revert them.

RESULTS

We found that AD models show accelerated aging and that factors specifically associated with Aβ pathology are involved. We discovered a few proteins whose abundance increases with AD progression, while the corresponding transcript levels remain stable, and showed that at least two of them (i.e., lfit3 and Syt11) co-localize with Aβ plaques in the brain. Finally, we found two NSAIDs (dexketoprofen and etodolac) and two anti-hypertensives (penbutolol and bendroflumethiazide) that overturn the cognitive impairment in AD mice while reducing Aβ plaques in the hippocampus and partially restoring the physiological levels of AD signature genes to wild-type levels.

CONCLUSIONS

The characterization of three AD mouse models at different disease stages provides an unprecedented view of AD pathology and how this differs from physiological aging. Moreover, our computational strategy to chemically revert AD signatures has shown that NSAID and anti-hypertensive drugs may still have an opportunity as anti-AD agents, challenging previous reports.

Sporadic Creutzfeldt-Jakob disease: Real-Time Quaking Induced Conversion (RT-QuIC) assay represents a major diagnostic advance

Sporadic Creutzfeldt-Jakob disease (sCJD) is a rare and fatal neurodegenerative disorder with an incidence of 1.5 to 2 cases per million population/year. The disease is caused by a proteinaceous infectious agent, named prion (or PrPSc), which arises from the conformational conversion of the cellular prion protein (PrPC). Once formed, PrPSc interacts with the normally folded PrPC coercing it to undergo similar structural rearrangement. The disease is highly heterogeneous from a clinical and neuropathological point of view. The origin of this variability lies in the aberrant structures acquired by PrPSc. At least six different sCJD phenotypes have been described and each of them is thought to be caused by a peculiar PrPSc strain. Definitive sCJD diagnosis requires brain analysis with the aim of identifying intracerebral accumulation of PrPSc which currently represents the only reliable biomarker of the disease. Clinical diagnosis of sCJD is very challenging and is based on the combination of several clinical, instrumental and laboratory tests representing surrogate disease biomarkers. Thanks to the advent of the ultrasensitive Real-Time Quaking-Induced Conversion (RT-QuIC) assay, PrPSc was found in several peripheral tissues of sCJD patients, sometimes even before the clinical onset of the disease. This discovery represents an important step forward for the clinical diagnosis of sCJD. In this manuscript, we present an overview of the current applications and future perspectives of RT-QuIC in the field of sCJD diagnosis.

Immune-Related Hub Genes and the Competitive Endogenous RNA Network in Alzheimer's Disease

BACKGROUND

The pathogenesis of Alzheimer's disease (AD) involves various immune-related phenomena; however, the mechanisms underlying these immune phenomena and the potential hub genes involved therein are unclear. An understanding of AD-related immune hub genes and regulatory mechanisms would help develop new immunotherapeutic targets.

OBJECTIVE

The aim of this study was to explore the hub genes and the mechanisms underlying the regulation of competitive endogenous RNA (ceRNA) in immune-related phenomena in AD pathogenesis.

METHODS

We used the GSE48350 data set from the Gene Expression Omnibus database and identified AD immune-related differentially expressed RNAs (DERNAs). We constructed protein-protein interaction (PPI) networks for differentially expressed mRNAs and determined the degree for screening hub genes. By determining Pearson's correlation coefficient and using StarBase, DIANA-LncBase, and Human MicroRNA Disease Database (HMDD), the AD immune-related ceRNA network was generated. Furthermore, we assessed the upregulated and downregulated ceRNA subnetworks to identify key lncRNAs.

RESULTS

In total, 552 AD immune-related DERNAs were obtained. Twenty hub genes, including PIK3R1, B2M, HLA-DPB1, HLA-DQB1, PIK3CA, APP, CDC42, PPBP, C3AR1, HRAS, PTAFR, RAB37, FYN, PSMD1, ACTR10, HLA-E, ARRB2, GGH, ALDOA, and VAMP2 were identified on PPI network analysis. Furthermore, upon microRNAs (miRNAs) inhibition, we identified LINC00836 and DCTN1-AS1 as key lncRNAs regulating the aforementioned hub genes.

CONCLUSION

AD-related immune hub genes include B2M, FYN, PIK3R1, and PIK3CA, and lncRNAs LINC00836 and DCTN1-AS1 potentially contribute to AD immune-related phenomena by regulating AD-related hub genes.

Integration of segmented regression analysis with weighted gene correlation network analysis identifies genes whose expression is remodeled throughout physiological aging in mouse tissues

Gene expression alterations occurring with aging have been described for a multitude of species, organs, and cell types. However, most of the underlying studies rely on static comparisons of mean gene expression levels between age groups and do not account for the dynamics of gene expression throughout the lifespan. These studies also tend to disregard the pairwise relationships between gene expression profiles, which may underlie commonly altered pathways and regulatory mechanisms with age. To overcome these limitations, we have combined segmented regression analysis with weighted gene correlation network analysis (WGCNA) to identify high-confidence signatures of aging in the brain, heart, liver, skeletal muscle, and pancreas of C57BL/6 mice in a publicly available RNA-Seq dataset (GSE132040). Functional enrichment analysis of the overlap of genes identified in both approaches showed that immune- and inflammation-related responses are prominently altered in the brain and the liver, while in the heart and the muscle, aging affects amino and fatty acid metabolism, and tissue regeneration, respectively, which reflects an age-related global loss of tissue function. We also explored sexual dimorphism in the aging mouse transcriptome and found the liver and the muscle to have the most pronounced gender differences in gene expression throughout the lifespan, particularly in proteostasis-related pathways. While the data showed little overlap among the age-dysregulated genes between tissues, aging triggered common biological processes in distinct tissues, which we highlight as important features of murine tissue physiological aging.

Tackling prion diseases: a review of the patent landscape

Introduction: Prion diseases are a class of rare and fatal neurodegenerative diseases for which no cure is currently available. They are characterized by conformational conversion of cellular prion protein (PrP^C) into the disease-associated 'scrapie' isoform (PrP^Sc). Under an etiological point of view, prion diseases can be divided into acquired, genetic, and idiopathic form, the latter of which are the most frequent.Areas covered: Therapeutic approaches targeting prion diseases are based on the use of chemical and nature-based compounds, targeting either PrP^C or PrP^Sc or other putative player in pathogenic mechanism. Other proposed anti-prion treatments include passive and active immunization strategies, peptides, aptamers, and PrP^C-directed RNA interference techniques. The treatment efficacy has been mainly assessed in cell lines or animal models of the disease testing their ability to reduce prion accumulation.Expert opinion: The assessed strategies focussing on the identification of an efficient anti-prion therapy faced various issues, which go from permeation of the blood brain barrier to immunological tolerance of the host. Indeed, the use of combinatory approaches, which could boost a synergistic anti-prion effect and lower the potential side effects of single treatments and may represent an extreme powerful and feasible way to tackle prion disease.

Polymorphic SERPINA3-R124C reduces pathogenesis of its wild type by shortening the lifetime of oligomeric Aβ

Amyloid beta (Aβ) 42 peptide accumulated in Alzheimer disease (AD) patients' brain, often colocalized with serine protease inhibitor family A member 3 (SERPINA3). Being a chaperon, SERPINA3 accelerated Aβ42 fibrillization. While analyzing chaperon activity of human SERPINA3 polymorphisms, we found SERPINA3-R124C played a role in protecting cells from Aβ42 cytotoxicity. SH-SY5Y cells exposed to Aβ42 preincubated with wild-type SERPINA3 (SERPINA3-WT) resulted in extended toxicity leading cell death whereas Aβ42 with SERPINA3-R124C resulted in less cytotoxicity. Transmission electron microscope and thioflavin T assay revealed that SERPINA3-R124C shortened lifetime of small soluble oligomer and maintained β-sheet rich protofibril-like aggregates for longer time compared to that of with SERPINA3-WT. Western blot assay confirmed that SERPINA3-R124C converted Aβ42 mostly into high molecular aggregates. Here, we demonstrate first time that polymorphic SERPINA3 acts as a benign chaperon by modulating the transition states of Aβ42, which may contribute to the reduction of AD risk.

Exosomal Aβ-Binding Proteins Identified by "In Silico" Analysis Represent Putative Blood-Derived Biomarker Candidates for Alzheimer´s Disease

The potential of exosomes as biomarker resources for diagnostics and even for therapeutics has intensified research in the field, including in the context of Alzheimer´s disease (AD). The search for disease biomarkers in peripheral biofluids is advancing mainly due to the easy access it offers. In the study presented here, emphasis was given to the bioinformatic identification of putative exosomal candidates for AD. The exosomal proteomes of cerebrospinal fluid (CSF), serum and plasma, were obtained from three databases (ExoCarta, EVpedia and Vesiclepedia), and complemented with additional exosomal proteins already associated with AD but not found in the databases. The final biofluids’ proteomes were submitted to gene ontology (GO) enrichment analysis and the exosomal Aβ-binding proteins that can constitute putative candidates were identified. Among these candidates, gelsolin, a protein known to be involved in inhibiting Abeta fibril formation, was identified, and it was tested in human samples. The levels of this Aβ-binding protein, with anti-amyloidogenic properties, were assessed in serum-derived exosomes isolated from controls and individuals with dementia, including AD cases, and revealed altered expression patterns. Identification of potential peripheral biomarker candidates for AD may be useful, not only for early disease diagnosis but also in drug trials and to monitor disease progression, allowing for a timely therapeutic intervention, which will positively impact the patient’s quality of life.

Polymorphic SERPINA3 prolongs oligomeric state of amyloid beta

Molecular chaperon SERPINA3 colocalizes with accumulated amyloid peptide in Alzheimer’s disease (AD) patient’s brain. From the QTL analysis, we narrowed down Serpina3 with two SNPs in senescence-accelerated mouse prone (SAMP) 8 strain. Our study showed SAMP8 type Serpina3 prolonged retention of oligomeric Aβ 42 for longer duration (72 hr) while observing under transmission electron microscope (TEM). From Western blot results, we confirmed presence of Aβ 42 oligomeric forms (trimers, tetramers) were maintained for longer duration only in the presences of SAMP8 type Serpina3. Using SH-SY5Y neuroblastoma cell line, we observed until 36 hr preincubated Aβ 42 with SAMP8 type Serpina3 caused neuronal cell death compared to 12 hr preincubated Aβ 42 with SAMR1 or JF1 type Serpina3 proteins. Similar results were found by extending this study to analyze the effect of polymorphism of SERPINA3 gene of the Japanese SNP database for geriatric research (JG-SNP). We observed that polymorphic SERPINA3 I308T (rs142398813) prolonged toxic oligomeric Aβ 42 forms till 48 hr in comparison to the presence wild type SERPINA3 protein, resulting neuronal cell death. From this study, we first clarified pathogenic regulatory role of polymorphic SERPINA3 in neurodegeneration.

Regional Differences in Neuroinflammation-Associated Gene Expression in the Brain of Sporadic Creutzfeldt-Jakob Disease Patients

Neuroinflammation is an essential part of neurodegeneration. Yet, the current understanding of neuroinflammation-associated molecular events in distinct brain regions of prion disease patients is insufficient to lay the ground for effective treatment strategies targeting this complex neuropathological process. To address this problem, we analyzed the expression of 800 neuroinflammation-associated genes to create a profile of biological processes taking place in the frontal cortex and cerebellum of patients who suffered from sporadic Creutzfeldt-Jakob disease. The analysis was performed using NanoString nCounter technology with human neuroinflammation panel+. The observed gene expression patterns were regionally and sub-regionally distinct, suggesting a variable neuroinflammatory response. Interestingly, the observed differences could not be explained by the molecular subtypes of sporadic Creutzfeldt-Jakob disease. Furthermore, analyses of canonical pathways and upstream regulators based on differentially expressed genes indicated an overlap between biological processes taking place in different brain regions. This suggests that even smaller-scale spatial data reflecting subtle changes in brain cells' functional heterogeneity and their immediate pathologic microenvironments are needed to explain the observed differential gene expression in a greater detail.

Comprehensive Profiling of Gene Expression in the Cerebral Cortex and Striatum of BTBRTF/ArtRbrc Mice Compared to C57BL/6J Mice

Mouse line BTBR T+ Iptr3^tf/J (hereafter referred as to BTBR/J) is a mouse strain that shows lower sociability compared to the C57BL/6J mouse strain (B6) and thus is often utilized as a model for autism spectrum disorder (ASD). In this study, we utilized another subline, BTBRTF/ArtRbrc (hereafter referred as to BTBR/R), and analyzed the associated brain transcriptome compared to B6 mice using microarray analysis, quantitative RT-PCR analysis, various bioinformatics analyses, and in situ hybridization. We focused on the cerebral cortex and the striatum, both of which are thought to be brain circuits associated with ASD symptoms. The transcriptome profiling identified 1,280 differentially expressed genes (DEGs; 974 downregulated and 306 upregulated genes, including 498 non-coding RNAs [ncRNAs]) in BTBR/R mice compared to B6 mice. Among these DEGs, 53 genes were consistent with ASD-related genes already established. Gene Ontology (GO) enrichment analysis highlighted 78 annotations (GO terms) including DNA/chromatin regulation, transcriptional/translational regulation, intercellular signaling, metabolism, immune signaling, and neurotransmitter/synaptic transmission-related terms. RNA interaction analysis revealed novel RNA–RNA networks, including 227 ASD-related genes. Weighted correlation network analysis highlighted 10 enriched modules including DNA/chromatin regulation, neurotransmitter/synaptic transmission, and transcriptional/translational regulation. Finally, the behavioral analyses showed that, compared to B6 mice, BTBR/R mice have mild but significant deficits in social novelty recognition and repetitive behavior. In addition, the BTBR/R data were comprehensively compared with those reported in the previous studies of human subjects with ASD as well as ASD animal models, including BTBR/J mice. Our results allow us to propose potentially important genes, ncRNAs, and RNA interactions. Analysis of the altered brain transcriptome data of the BTBR/R and BTBR/J sublines can contribute to the understanding of the genetic underpinnings of autism susceptibility.

Small-molecule modulators of serine protease inhibitor proteins (serpins)

Serine protease inhibitors (serpins) are a large family of proteins that regulate and control crucial physiological processes, such as inflammation, coagulation, thrombosis and thrombolysis, and immune responses. The extraordinary impact that these proteins have on numerous crucial pathways makes them an attractive target for drug discovery. In this review, we discuss recent advances in research on small-molecule modulators of serpins, examine their mode of action, analyse the structural data from crystallised protein-ligand complexes, and highlight the potential obstacles and possible therapeutic perspectives. The application of in silico methods for rational drug discovery is also summarised. In addition, we stress the need for continued research in this field.

Regional, cellular and species difference of two key neuroinflammatory genes implicated in schizophrenia

The transcription factor nuclear factor kappa B (NF-κB) regulates the expression of many inflammatory genes that are overexpressed in a subset of people with schizophrenia. Transcriptional reduction in one NF-κB inhibitor, Human Immunodeficiency Virus Enhancer Binding Protein 2 (HIVEP2), is found in the brain of patients, aligning with evidence of NF-κB over-activity. Cellular co-expression of HIVEP2 and cytokine transcripts is a prerequisite for a direct effect of HIVEP2 on pro-inflammatory transcription, and we do not know if changes in HIVEP2 and markers of neuroinflammation are occurring in the same brain cell type. We performed in situ hybridisation on postmortem dorsolateral prefrontal cortex tissue to map and compare the expression of HIVEP2 and Serpin Family A Member 3 (SERPINA3), one of the most consistently increased inflammatory genes in schizophrenia, between schizophrenia patients and controls. We find that HIVEP2 expression is neuronal and is decreased in almost all grey matter cortical layers in schizophrenia patients with neuroinflammation, and that SERPINA3 is increased in the dorsolateral prefrontal cortex grey matter and white matter in the same group of patients. We are the first to map the upregulation of SERPINA3 to astrocytes and to some neurons, and find evidence to suggest that blood vessel-associated astrocytes are the main cellular source of SERPINA3 in the schizophrenia cortex. We show that a lack of HIVEP2 in mice does not cause astrocytic upregulation of Serpina3n but does induce its transcription in neurons. We speculate that HIVEP2 downregulation is not a direct cause of astrocytic pro-inflammatory cytokine synthesis in schizophrenia but may contribute to neuronally-mediated neuroinflammation.

The Accumulation of Tau-Immunoreactive Hippocampal Granules and Corpora Amylacea Implicates Reactive Glia in Tau Pathogenesis during Aging

The microtubule-associated tau protein forms pathological inclusions that accumulate in an age-dependent manner in tauopathies including Alzheimer's disease (AD). Since age is the major risk factor for AD, we examined endogenous tau species that evolve during aging in physiological and diseased conditions. In aged mouse brain, we found tau-immunoreactive clusters embedded within structures that are reminiscent of periodic acid-Schiff (PAS) granules. We showed that PAS granules harbor distinct tau species that are more prominent in 3xTg-AD mice. Epitope profiling revealed hypo-phosphorylated rather than hyper-phosphorylated tau commonly observed in tauopathies. High-resolution imaging and 3D reconstruction suggest a link between tau clusters, reactive astrocytes, and microglia, indicating that early tau accumulation may promote neuroinflammation during aging. Using postmortem human brain, we identified tau as a component of corpora amylacea (CA), age-related structures that are functionally analogous to PAS granules. Overall, our study supports neuroimmune dysfunction as a precipitating event in tau pathogenesis.

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Tau is present in mouse hippocampal granules and human corpora amylacea

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Tau accumulates with age in hippocampal granules and is accelerated in 3xTg-AD mice

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Tau immunoreactive corpora amylacea are present in Alzheimer's disease brain

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Age-related tau deposits are associated with reactive astrocytes

Region-specific glial homeostatic signature in prion diseases is replaced by a uniform neuroinflammation signature, common for brain regions and prion strains with different cell tropism

Chronic neuroinflammation is recognized as a major neuropathological hallmark in a broad spectrum of neurodegenerative diseases including Alzheimer's, Parkinson's, Frontal Temporal Dementia, Amyotrophic Lateral Sclerosis, and prion diseases. Both microglia and astrocytes exhibit region-specific homeostatic transcriptional identities, which under chronic neurodegeneration, transform into reactive phenotypes in a region- and disease-specific manner. Little is known about region-specific identity of glia in prion diseases. The current study was designed to determine whether the region-specific homeostatic signature of glia changes with the progression of prion diseases, and whether these changes occur in a region-dependent or universal manner. Also of interest was whether different prion strains give rise to different reactive phenotypes. To answer these questions, we analyzed gene expression in the thalamus, cortex, hypothalamus and hippocampus of mice infected with 22L and ME7 prion strains using a Nanostring Neuroinflammation panel at the subclinical, early clinical and advanced stages of the disease. We found that at the preclinical stage of the disease, the region-specific homeostatic identities were preserved. However, with the appearance of clinical signs, the region-specific signatures were partially lost and replaced with a neuroinflammation signature. While the same sets of genes were activated by both prion strains, the timing of neuroinflammation and the degree of activation in different brain regions was strain-specific. Changes in astrocyte function scored at the top of the activated pathways. Moreover, clustering analysis suggested that the astrocyte function pathway responded to prion infection prior to the Activated Microglia or Neuron and Neurotransmission pathways. The current work established neuroinflammation gene expression signature associated with prion diseases. Our results illustrate that with the disease progression, the region-specific homeostatic transcriptome signatures are replaced by the region-independent neuroinflammation signature, which is common for prion strains with different cell tropism. The prion-associated neuroinflammation signature identified in the current study overlapped only partially with the microglia degenerative phenotype and the disease-associated microglia phenotype reported for animal models of other neurodegenerative diseases.

CSF SerpinA1 in Creutzfeldt-Jakob disease and frontotemporal lobar degeneration

Objective

SerpinA1 (alpha‐1 antitrypsin) is an acute inflammatory protein, which seems to play a role in neurodegeneration and neuroinflammation. In Alzheimer’s disease and synucleinopathies, SerpinA1 is overexpressed in the brain and the cerebrospinal fluid (CSF) showing abnormal patterns of its charge isoforms. To date, no comprehensive studies explored SerpinA1 CSF isoforms in Creutzfeldt–Jakob disease (CJD) and frontotemporal lobar degeneration (FTLD).

Methods

Using a capillary isoelectric focusing immunoassay, we analyzed CSF SerpinA1 isoforms in control cases (n = 31) and patients with a definite or probable diagnosis of CJD (n=77) or FTLD (n = 30), belonging to several disease subtypes.

Results

The overall SerpinA1 signal was significantly higher than in controls in CJD subtypes linked to abnormal prion protein (PrP^Sc) type 1, such as sporadic CJD (sCJD) MM(V)1, and in FTLD‐TDP. Moreover, CJD linked to PrP^Sc type 1 and FTLD‐TAU groups showed a significant relative increase of acidic and basic isoforms in comparison with controls, thereby forming two distinct SerpinA1 isoform profiles.

Interpretation

CJD linked to PrP^Sc type 1 and FTLD show a differential upregulation and post‐translational modifications of CSF SerpinA1. Further studies are needed to clarify whether these findings may reflect a common, albeit disease‐specific, pathogenetic mechanism related to neurodegeneration.

Inhibition of SERPINA3N-dependent neuroinflammation is essential for melatonin to ameliorate trimethyltin chloride-induced neurotoxicity

Trimethyltin chloride (TMT) is a potent neurotoxin that causes neuroinflammation and neuronal cell death. Melatonin is a well-known anti-inflammatory agent with significant neuroprotective activity. Male C57BL/6J mice were intraperitoneally injected with a single dose of melatonin (10 mg/kg) before exposure to TMT (2.8 mg/kg, ip). Thereafter, the mice received melatonin (10 mg/kg, ip) once a day for another three consecutive days. Melatonin dramatically alleviated TMT-induced neurotoxicity in mice by attenuating hippocampal neuron loss, inhibiting epilepsy-like seizures, and ameliorating memory deficits. Moreover, melatonin markedly suppressed TMT-induced neuroinflammatory responses and astrocyte activation, as shown by a decrease in inflammatory cytokine production as well as the downregulation of neurotoxic reactive astrocyte phenotype markers. Mechanistically, serine peptidase inhibitor clade A member 3N (SERPINA3N) was identified as playing a central role in the protective effects of melatonin based on quantitative proteome and bioinformatics analysis. Most importantly, melatonin significantly suppressed TMT-induced SERPINA3N upregulation at both the mRNA and protein levels. The overexpression of Serpina3n in the mouse hippocampus abolished the protective effects of melatonin on TMT-induced neuroinflammation and neurotoxicity. Melatonin protected cells against TMT-induced neurotoxicity by inhibiting SERPINA3N-mediated neuroinflammation. Melatonin may be a promising and practical agent for reducing TMT-induced neurotoxicity in clinical practice.

Target Genes of Autism Risk Loci in Brain Frontal Cortex

Autism spectrum disorder (ASD) is a complex neuropsychiatric disorder. A number of genetic risk loci have been identified for ASD from genome-wide association studies (GWAS); however, their target genes in relevant tissues and cell types remain to be investigated. The frontal cortex is a key region in the human brain for communication and cognitive function. To identify risk genes contributing to potential dysfunction in the frontal cortex of ASD patients, we took an in silico approach integrating multi-omics data. We first found genes with expression in frontal cortex tissue that correlates with ASD risk loci by leveraging expression quantitative trait loci (eQTLs) information. Among these genes, we then identified 76 genes showing significant differential expression in the frontal cortex between ASD cases and controls in microarray datasets and further replicated four genes with RNA-seq data. Among the ASD GWAS single nucleotide polymorphisms (SNPs) correlating with the 76 genes, 20 overlap with histone marks and 40 are associated with gene methylation level. Thus, through multi-omics data analyses, we identified genes that may work as target genes of ASD risk loci in the brain frontal cortex.

Brain aging: A Ianus-faced player between health and neurodegeneration

Neurodegenerative diseases are incurable debilitating disorders characterized by structural and functional neuronal loss. Approximately 30 million people are affected worldwide, and this number is predicted to reach more than 150 million by 2050. Neurodegenerative disorders include Alzheimer's, Parkinson's, and prion diseases among others. These disorders are characterized by the accumulation of aggregating proteins forming amyloid, responsible for the disease-associated pathological lesions. The aggregation of amyloidogenic proteins can result either in gaining of toxic functions, derived from the damage provoked by these deposits in affected tissue, or in a loss of functions, due to the sequestration and the consequent inability of the aggregating protein to ensure its physiological role. While it is widely accepted that aging represents the main risk factor for neurodegeneration, there is still no clear cut-off line between the two conditions. Indeed, many of the pathways that are commonly altered in neurodegeneration-misfolded protein accumulation, chronic inflammation, mitochondrial dysfunction, impaired iron homeostasis, epigenetic modifications-have been often correlated also with healthy aging. This overlap could be explained by the fact that the continuous accumulation of cellular damages, together with a progressive decline in metabolic efficiency during aging, makes the neurons more vulnerable to toxic injuries. When a given threshold is exceeded, all these alterations might give rise to pathological phenotypes that ultimately lead to neurodegeneration.

Analysis of RNA Expression Profiles Identifies Dysregulated Vesicle Trafficking Pathways in Creutzfeldt-Jakob Disease

Functional genomics applied to the study of RNA expression profiles identified several abnormal molecular processes in experimental prion disease. However, only a few similar studies have been carried out to date in a naturally occurring human prion disease. To better characterize the transcriptional cascades associated with sporadic Creutzfeldt-Jakob disease (sCJD), the most common human prion disease, we investigated the global gene expression profile in samples from the frontal cortex of 10 patients with sCJD and 10 non-neurological controls by microarray analysis. The comparison identified 333 highly differentially expressed genes (hDEGs) in sCJD. Functional enrichment Gene Ontology analysis revealed that hDEGs were mainly associated with synaptic transmission, including GABA (q value = 0.049) and glutamate (q value = 0.005) signaling, and the immune/inflammatory response. Furthermore, the analysis of cellular components performed on hDEGs showed a compromised regulation of vesicle-mediated transport with mainly up-regulated genes related to the endosome (q value = 0.01), lysosome (q value = 0.04), and extracellular exosome (q value < 0.01). A targeted analysis of the retromer core component VPS35 (vacuolar protein sorting-associated protein 35) showed a down-regulation of gene expression (p value= 0.006) and reduced brain protein levels (p value= 0.002). Taken together, these results confirm and expand previous microarray expression profile data in sCJD. Most significantly, they also demonstrate the involvement of the endosomal-lysosomal system. Since the latter is a common pathogenic pathway linking together diseases, such as Alzheimer's and Parkinson's, it might be the focus of future studies aimed to identify new therapeutic targets in neurodegenerative diseases.

Hemoglobin mRNA Changes in the Frontal Cortex of Patients with Neurodegenerative Diseases

Background: Hemoglobin is the major protein found in erythrocytes, where it acts as an oxygen carrier molecule. In recent years, its expression has been reported also in neurons and glial cells, although its role in brain tissue remains still unknown. Altered hemoglobin expression has been associated with various neurodegenerative disorders. Here, we investigated hemoglobin mRNA levels in brains of patients affected by variant, iatrogenic, and sporadic forms of Creutzfeldt-Jakob disease (vCJD, iCJD, sCJD, respectively) and in different genetic forms of prion diseases (gPrD) in comparison to Alzheimer's disease (AD) subjects and age-matched controls. Methods: Total RNA was obtained from the frontal cortex of vCJD (n = 20), iCJD (n = 11), sCJD (n = 23), gPrD (n = 30), and AD (n = 14) patients and age-matched controls (n = 30). RT-qPCR was performed for hemoglobin transcripts HBB and HBA1/2 using four reference genes for normalization. In addition, expression analysis of the specific erythrocyte marker ALAS2 was performed in order to account for blood contamination of the tissue samples. Hba1/2 and Hbb protein expression was then investigated with immunofluorescence and confocal microscope analysis. Results: We observed a significant up-regulation of HBA1/2 in vCJD brains together with a significant down-regulation of HBB in iCJD. In addition, while in sporadic and genetic forms of prion disease hemoglobin transcripts did not shown any alterations, both chains display a strong down-regulation in AD brains. These results were confirmed also at a protein level. Conclusions: These data indicate distinct hemoglobin transcriptional responses depending on the specific alterations occurring in different neurodegenerative diseases. In particular, the initial site of misfolding event (central nervous system vs. peripheral tissue)-together with specific molecular and conformational features of the pathological agent of the disease-seem to dictate the peculiar hemoglobin dysregulation found in prion and non-prion neurodegenerative disorders. In addition, these results suggest that gene expression of HBB and HBA1/2 in brain tissue is differentially affected by distinct prion and prion-like aggregating protein strains. Validation of these results in more accessible tissues could prompt the development of novel diagnostic tests for neurodegenerative disorders.