Cerebrospinal fluid proteome of patients with acute Lyme disease

Pathogenesis of Alzheimer's disease: Involvement of the choroid plexus

The choroid plexus (ChP) produces and is bathed in the cerebrospinal fluid (CSF), which in aging and Alzheimer's disease (AD) shows extensive proteomic alterations including evidence of inflammation. Considering inflammation hampers functions of the involved tissues, the CSF abnormalities reported in these conditions are suggestive of ChP injury. Indeed, several studies document ChP damage in aging and AD, which nevertheless remains to be systematically characterized. We here report that the changes elicited in the CSF by AD are consistent with a perturbed aging process and accompanied by aberrant accumulation of inflammatory signals and metabolically active proteins in the ChP. Magnetic resonance imaging (MRI) imaging shows that these molecular aberrancies correspond to significant remodeling of ChP in AD, which correlates with aging and cognitive decline. Collectively, our preliminary post-mortem and in vivo findings reveal a repertoire of ChP pathologies indicative of its dysfunction and involvement in the pathogenesis of AD. HIGHLIGHTS: Cerebrospinal fluid changes associated with aging are perturbed in Alzheimer's disease Paradoxically, in Alzheimer's disease, the choroid plexus exhibits increased cytokine levels without evidence of inflammatory activation or infiltrates In Alzheimer's disease, increased choroid plexus volumes correlate with age and cognitive performance.

A systems biology approach to better understand human tick-borne diseases

Tick-borne diseases (TBDs) are a growing global health concern. Despite extensive studies, ill-defined tick-associated pathologies remain with unknown aetiologies. Human immunological responses after tick bite, and inter-individual variations of immune-response phenotypes, are not well characterised. Current reductive experimental methodologies limit our understanding of more complex tick-associated illness, which results from the interactions between the host, tick, and microbes. An unbiased, systems-level integration of clinical metadata and biological host data - obtained via transcriptomics, proteomics, and metabolomics - offers to drive the data-informed generation of testable hypotheses in TBDs. Advanced computational tools have rendered meaningful analysis of such large data sets feasible. This review highlights the advantages of integrative system biology approaches as essential for understanding the complex pathobiology of TBDs.

COR388 (atuzaginstat): an investigational gingipain inhibitor for the treatment of Alzheimer disease

INTRODUCTION

Evidence from in vitro and in vivo studies demonstrates that amyloid beta (Aβ) oligomers have potent, broad-spectrum antimicrobial properties created by fibrils that entrap pathogens and disrupt their membranes. Data suggest that Aβ may play a protective role in the innate immune response to microbial infections and that Aβ in the brain plays a damaging role when the inflammatory response is not well controlled.

AREAS COVERED

This paper describes the relationship between periodontal disease and Alzheimer disease (AD), the role of Porphyromonas gingivalis and its secreted gingipains in AD, and the potential of the gingipain inhibitor atuzaginstat (COR388) to modulate AD neuropathologies.

EXPERT OPINION

P. gingivalis is opsonized by Aβ42, is capable of entering the brain, and is an accelerant of neuropathologies in rodent models of AD. Thus, in our opinion, this bacteria is highly likely to be a pathogen capable of initiating or precipitating the progression of AD, which agrees with the pathogen hypothesis of clinical AD development.

Early Disseminated Lyme Disease: Cranial Neuropathy, Meningitis, and Polyradiculopathy

Early disseminated Lyme disease can involve the peripheral or central nervous system, but with early diagnosis and treatment, prognosis for full recovery is excellent. The typical clinical presentations of neuroborreliosis are highlighted, and an approach to diagnosis and treatment is described.

Integrative Transcriptome and Proteome Analyses Provide New Insights Into the Interaction Between Live Borrelia burgdorferi and Frontal Cortex Explants of the Rhesus Brain

Borrelia burgdorferi (Bb), which is neurotropic, can attack the central nervous system (CNS), leading to the development of various neurologic symptoms. The pathogenesis of Lyme neuroborreliosis (LNB) remains poorly understood. Presently, there is a lack of knowledge of the changes in mRNA and proteins in the CNS following early disseminated Lyme disease. Explants from the frontal cortex of 3 rhesus brains were incubated with medium alone or with medium containing live Bb for 6, 12, or 24 hours. Then, we analyzed identified mRNA and proteins in the frontal cortex tissues, allowing for an in-depth view of the transcriptome and proteome for a macroscopic and unbiased understanding of early disseminated Lyme disease in the brain. Through bioinformatics analysis, a complex network of enriched pathways that were mobilized during the progression of Lyme spirochete infection was described. Furthermore, based on the analysis of omics data, translational regulation, glycosaminoglycan/proteoglycan-binding activity in colonization and dissemination to tissues, disease-associated genes, and synaptic function were enriched, which potentially play a role in pathogenesis during the interaction between frontal cortex tissues and spirochetes. These integrated omics results provide unbiased and comprehensive information for the further understanding of the molecular mechanisms of LNB.

The Lyme disease bacterium, Borrelia burgdorferi, stimulates an inflammatory response in human choroid plexus epithelial cells

The main functions of the choroid plexus (CP) are the production of cerebral spinal fluid (CSF), the formation of the blood-CSF barrier, and regulation of immune response. This barrier allows for the exchange of specific nutrients, waste, and peripheral immune cells between the blood stream and CSF. Borrelia burgdorferi (Bb), the causative bacteria of Lyme disease, is associated with neurological complications including meningitis-indeed, Bb has been isolated from the CSF of patients. While it is accepted that B. burgdorferi can enter the central nervous system (CNS) of patients, it is unknown how the bacteria crosses this barrier and how the pathogenesis of the disease leads to the observed symptoms in patients. We hypothesize that during infection Borrelia burgdorferi will induce an immune response conducive to the chemotaxis of immune cells and subsequently lead to a pro-inflammatory state with the CNS parenchyma. Primary human choroid plexus epithelial cells were grown in culture and infected with B. burgdorferi strain B31 MI-16 for 48 hours. RNA was isolated and used for RNA sequencing and RT-qPCR validation. Secreted proteins in the supernatant were analyzed via ELISA. Transcriptome analysis based on RNA sequencing determined a total of 160 upregulated genes and 98 downregulated genes. Pathway and biological process analysis determined a significant upregulation in immune and inflammatory genes specifically in chemokine and interferon related pathways. Further analysis revealed downregulation in genes related to cell to cell junctions including tight and adherens junctions. These results were validated via RT-qPCR. Protein analysis of secreted factors showed an increase in inflammatory chemokines, corresponding to our transcriptome analysis. These data further demonstrate the role of the CP in the modulation of the immune response in a disease state and give insight into the mechanisms by which Borrelia burgdorferi may disseminate into, and act upon, the CNS. Future experiments aim to detail the impact of B. burgdorferi on the blood-CSF-barrier (BCSFB) integrity and inflammatory response within animal models.

Mass spectrometry-based proteomic techniques to identify cerebrospinal fluid biomarkers for diagnosing suspected central nervous system infections. A systematic review

OBJECTIVES

Central nervous system (CNS) infections account for considerable death and disability every year. An urgent research priority is scaling up diagnostic capacity, and introduction of point-of-care tests. We set out to assess current evidence for the application of mass spectrometry (MS) peptide sequencing in identification of diagnostic biomarkers for CNS infections.

METHODS

We performed a systematic review (PROSPEROCRD42018104257) using PRISMA guidelines on use of MS to identify cerebrospinal fluid (CSF) biomarkers for diagnosing CNS infections. We searched PubMed, Embase, Web of Science, and Cochrane for articles published from 1 January 2000 to 1 February 2019, and contacted experts. Inclusion criteria involved primary research except case reports, on the diagnosis of infectious diseases except HIV, applying MS to human CSF samples, and English language.

RESULTS

4,620 papers were identified, of which 11 were included, largely confined to pre-clinical biomarker discovery, and eight (73%) published in the last five years. 6 studies performed further work termed verification or validation. In 2 of these studies, it was possible to extract data on sensitivity and specificity of the biomarkers detected by ELISA, ranging from 89-94% and 58-92% respectively.

CONCLUSIONS

The findings demonstrate feasibility and potential of the methods in a variety of infectious diseases, but emphasise the need for strong interdisciplinary collaborations to ensure appropriate study design and biomarker validation.

Quantitative proteomics of synaptosome S-nitrosylation in Alzheimer's disease

Increasing evidence suggests that both synaptic loss and neuroinflammation constitute early pathologic hallmarks of Alzheimer's disease. A downstream event during inflammatory activation of microglia and astrocytes is the induction of nitric oxide synthase type 2, resulting in an increased release of nitric oxide and the post-translational S-nitrosylation of protein cysteine residues. Both early events, inflammation and synaptic dysfunction, could be connected if this excess nitrosylation occurs on synaptic proteins. In the long term, such changes could provide new insight into patho-mechanisms as well as biomarker candidates from the early stages of disease progression. This study investigated S-nitrosylation in synaptosomal proteins isolated from APP/PS1 model mice in comparison to wild type and NOS2^-/- mice, as well as human control, mild cognitive impairment and Alzheimer's disease brain tissues. Proteomics data were obtained using an established protocol utilizing an isobaric mass tag method, followed by nanocapillary high performance liquid chromatography tandem mass spectrometry. Statistical analysis identified the S-nitrosylation sites most likely derived from an increase in nitric oxide (NO) in dependence of presence of AD pathology, age and the key enzyme NOS2. The resulting list of candidate proteins is discussed considering function, previous findings in the context of neurodegeneration, and the potential for further validation studies.

The Physiological Roles of Amyloid-β Peptide Hint at New Ways to Treat Alzheimer's Disease

Amyloid-ß (Aß) is best known as the misfolded peptide that is involved in the pathogenesis of Alzheimer's disease (AD), and it is currently the primary therapeutic target in attempts to arrest the course of this disease. This notoriety has overshadowed evidence that Aß serves several important physiological functions. Aß is present throughout the lifespan, it has been found in all vertebrates examined thus far, and its molecular sequence shows a high degree of conservation. These features are typical of a factor that contributes significantly to biological fitness, and this suggestion has been supported by evidence of functions that are beneficial for the brain. The putative roles of Aß include protecting the body from infections, repairing leaks in the blood-brain barrier, promoting recovery from injury, and regulating synaptic function. Evidence for these beneficial roles comes from in vitro and in vivo studies, which have shown that the cellular production of Aß rapidly increases in response to a physiological challenge and often diminishes upon recovery. These roles are further supported by the adverse outcomes of clinical trials that have attempted to deplete Aß in order to treat AD. We suggest that anti-Aß therapies will produce fewer adverse effects if the known triggers of Aß deposition (e.g., pathogens, hypertension, and diabetes) are addressed first.

Insights into the human brain proteome: Disclosing the biological meaning of protein networks in cerebrospinal fluid

Cerebrospinal fluid (CSF) is an excellent source of biological information regarding the nervous system, once it is in close contact and accurately reflects alterations in this system. Several studies have analyzed differential protein profiles of CSF samples between healthy and diseased human subjects. However, the pathophysiological mechanisms and how CSF proteins relate to diseases are still poorly known. By applying bioinformatics tools, we attempted to provide new insights on the biological and functional meaning of proteomics data envisioning the identification of putative disease biomarkers. Bioinformatics analysis of data retrieved from 99 mass spectrometry (MS)-based studies on CSF profiling highlighted 1985 differentially expressed proteins across 49 diseases. A large percentage of the modulated proteins originate from exosome vesicles, and the majority are involved in either neuronal cell growth, development, maturation, migration, or neurotransmitter-mediated cellular communication. Nevertheless, some diseases present a unique CSF proteome profile, which were critically analyzed in the present study. For instance, 48 proteins were found exclusively upregulated in the CSF of patients with Alzheimer's disease and are mainly involved in steroid esterification and protein activation cascade processes. A higher number of exclusively upregulated proteins were found in the CSF of patients with multiple sclerosis (76 proteins) and with bacterial meningitis (70 proteins). Whereas in multiple sclerosis, these proteins are mostly involved in the regulation of RNA metabolism and apoptosis, in bacterial meningitis the exclusively upregulated proteins participate in inflammation and antibacterial humoral response, reflecting disease pathogenesis. The exploration of the contribution of exclusively upregulated proteins to disease pathogenesis will certainly help to envision potential biomarkers in the CSF for the clinical management of nervous system diseases.

The Challenges and Advances in Diagnosis of Vector-Borne Diseases: Where Do We Stand?

Vector-borne diseases (VBD) are of major importance to human and animal health. In recent years, VBD have been emerging or re-emerging in many geographical areas, alarming new disease threats and economic losses. The precise diagnosis of many of these diseases still remains a major challenge because of the lack of comprehensive data available on accurate and reliable diagnostic methods. Here, we conducted a systematic and in-depth review of the former, current, and upcoming techniques employed for the diagnosis of VBD.

Characterization of individual mouse cerebrospinal fluid proteomes

Analysis of cerebrospinal fluid (CSF) offers key insight into the status of the CNS. Characterization of murine CSF proteomes can provide a valuable resource for studying CNS injury and disease in animal models. However, the small volume of CSF in mice has thus far limited individual mouse proteome characterization. Through nonterminal CSF extractions in C57Bl/6 mice and high-resolution 2D-LC MS/MS analysis of individual murine samples, we report the most comprehensive proteome characterization of individual murine CSF to date. We identified a total of 566 unique proteins, including 128 proteins from three individual CSF samples that have been previously identified in brain tissue. Our methods and analysis provide a mechanism for individual murine CSF proteome analysis. The data are available in the ProteomeXchange with identifier PXD000248 (http://proteomecentral.proteomexchange.org/dataset/PXD000248).