Emerging Microbial and Viral Infections of the Central Nervous System

This review focuses on emerging viral and bacterial infections in the human central nervous system (CNS) that are responsible for significant global morbidity and mortality. These infections include those responsible for acute neurological disease such as meningitis and encephalitis as well those associated with chronic neurodegenerative conditions. Recent changes in climate conditions and pollution have been precipitating factors leading to the emergence of many of these pathogenic organisms. In addition, increased urbanization, global travel, life span, and exposure to new vectors have promoted the organisms’ spread across the globe. Categorization of many of these organisms includes identification of new species, recognition of new tropism to the CNS, spread into naïve demographic areas, increased human contact with zoonotic repositories including insect vectors, and reemergence of well-known organisms. These mechanisms are highlighted for the different organisms included in this review. Other mechanisms for CNS emergence such as genetic mutation of the organisms and immunosuppression and/or immunosenescence of the host are addressed. Viral and bacterial infections in chronic neurodegenerative diseases traditionally not thought to be infectious are considered. Although this review cannot be all-inclusive, the organisms included represent a sampling of extremely important microbes and their role in CNS pathogenesis in the twenty-first century

Chlamydia pneumoniae Infection of Monocytes in vitro Stimulates Innate and Adaptive Immune Responses Relevant to those in Alzheimer\u27s Disease.

Background: Alzheimer\u27s disease (AD) is a progressive neurodegenerative disorder in which infection with Chlamydia pneumoniae (Cpn) has been associated. Cpn is an obligate intracellular respiratory pathogen that may enter the central nervous system (CNS) following infection and trafficking of monocytes through the blood-brain barrier. Following this entry, these cells may secrete pro-inflammatory cytokines and chemokines that have been identified in the AD brain, which have been thought to contribute to AD neurodegeneration. The objectives of this work were: (i) to determine if Cpn infection influences monocyte gene transcript expression at 48 hours post-infection and (ii) to analyze whether pro-inflammatory cytokines are produced and secreted from these cells over 24 to 120 hours post-infection. Methods: Gene transcription was analyzed by RT-PCR using an innate and adaptive immunity microarray with 84 genes organized into 5 functional categories: inflammatory response, host defense against bacteria, antibacterial humoral response, septic shock, and cytokines, chemokines and their receptors. Statistical analysis of the results was performed using the Student\u27s t-test. P-values ≤ 0.05 were considered to be significant. ELISA was performed on supernatants from uninfected and Cpn-infected THP1 monocytes followed by statistical analysis with ANOVA. Results: When Cpn-infected THP1 human monocytes were compared to control uninfected monocytes at 48 hours post-infection, 17 genes were found to have a significant 4-fold or greater expression, and no gene expression was found to be down-regulated. Furthermore, cytokine secretion (IL-1ß, IL-6, IL-8) appears to be maintained for an extended period of infection. Conclusions: Utilizing RT-PCR and ELISA techniques, our data demonstrate that Cpn infection of THP1 human monocytes promotes an innate immune response and suggests a potential role in the initiation of inflammation in sporadic/late-onset Alzheimer\u27s disease

Evaluation of Smell and miRNA Biomarkers in Alzheimer’s Disease (AD)

Abstract and poster under embargo until May 31, 2019

Immunohistological detection of Chlamydia pneumoniae in the Alzheimer's disease brain

<p>Abstract</p> <p>Background</p> <p>Sporadic late-onset Alzheimer's disease (AD) appears to evolve from an interplay between genetic and environmental factors. One environmental factor that continues to be of great interest is that of <it>Chlamydia pneumoniae </it>infection and its association with late-onset disease. Detection of this organism in clinical and autopsy samples has proved challenging using a variety of molecular and histological techniques. Our current investigation utilized immunohistochemistry with a battery of commercially available anti-<it>C. pneumoniae </it>antibodies to determine whether <it>C. pneumoniae </it>was present in areas typically associated with AD neuropathology from 5 AD and 5 non-AD control brains.</p> <p>Results</p> <p>Immunoreactivity for <it>C. pneumoniae </it>antigens was observed both intracellularly in neurons, neuroglia, endothelial cells, and peri-endothelial cells, and extracellularly in the frontal and temporal cortices of the AD brain with multiple <it>C. pneumoniae</it>-specific antibodies. This immunoreactivity was seen in regions of amyloid deposition as revealed by immunolabeling with two different anti-beta amyloid antibodies. Thioflavin S staining, overlaid with <it>C. pneumoniae </it>immunolabeling, demonstrated no direct co-localization of the organism and amyloid plaques. Further, the specificity of <it>C. pneumoniae </it>labeling of AD brain sections was demonstrated using <it>C. pneumoniae </it>antibodies pre-absorbed against amyloid β 1-40 and 1-42 peptides.</p> <p>Conclusions</p> <p>Anti-<it>C. pneumoniae </it>antibodies, obtained commercially, identified both typical intracellular and atypical extracellular <it>C. pneumoniae </it>antigens in frontal and temporal cortices of the AD brain. <it>C. pneumoniae</it>, amyloid deposits, and neurofibrillary tangles were present in the same regions of the brain in apposition to one another. Although additional studies are required to conclusively characterize the nature of Chlamydial immunoreactivity in the AD brain, these results further implicate <it>C. pneumoniae </it>infection with the pathogenesis of Alzheimer's disease.</p

Analysis of Chlamydia pneumoniae and AD-like Pathology in the Brains of BALB/c Mice Following Direct Intra-cranial Infection

Alzheimer’s disease (AD) is an age-related progressive neurodegenerative disorder and the most common form of dementia. The pathology in the central nervous system (CNS) impairs memory and cognition, hindering the capabilities and the quality of life of the individual. This project continues studying the role of infection and Alzheimer’s disease, as previous studies in this laboratory have done, and contributes to the overall understanding of the possible causes of this disease. In this study, BALB/c mice were infected, via direct intracranial injection, with a respiratory isolate (AR-39) of Chlamydia pneumoniae. Their brains were analyzed at 7 and 14 days post-infection, via immunohistochemistry, for the presence of C. pneumoniae, amyloid deposits and activated glial cells. The goal of this project was to measure the location and degree of C. pneumoniae burden, amyloid deposition and glial cell activation in the CNS following direct intracranial injection and to compare this data with results obtained from previous studies in this laboratory. We hypothesized that C. pneumoniae antigen and activated inflammatory cells will be observed in the infected mouse brains following direct intracranial injection and Aβ deposition will be observed in areas where inflammation occurs. C. pneumoniae, amyloid deposits and activated glial cells were detected in the brains following direct intracranial infection with C. pneumoniae. In infected mice there was an approximate 3.5-fold increase of C. pneumoniae antigen burden compared to uninfected mice at day 7 and there was an approximate 5.5-fold increase of C. pneumoniae antigen burden compared to uninfected mice at day 14. The burden of C. pneumoniae antigen, in the infected mice, increased 1.009-fold (no change) from day 7 to day 14 post-infection. The amyloid burden in infected mice increased approximately 3-fold compared to uninfected mice at day 7 and increased greater than10-fold compared to uninfected mice at day 14. The burden of amyloid, in the infected mice, increased 7-fold from day 7 to 14. From 7 to 14 days post-infection the C. pneumoniae and amyloid deposits located near the injection site spread distally from this location to other regions of the brain. Global activation of glia was observed in the CNS of infected mice at both 7 and 14 days post-infection. This data confirms that C. pneumoniae is capable of establishing an infection in the CNS. Although deposits were observed, the lack of a substantial amount of amyloid deposits suggested that the generation of deposits may require longer than 14 days following C. pneumoniae infection. As early as 7 days post-infection, inflammation is observed in response to the presence of C. pneumoniae and/or soluble amyloid in the CNS and the contribution of both infection with C. pneumoniae and the presence of soluble amyloid elicit the inflammatory response that presumably precedes and contributes to amyloid depositionhttps://digitalcommons.pcom.edu/posters/1003/thumbnail.jp

Detection of Bacterial Antigens and Alzheimer\u27s Disease-like Pathology in the Central Nervous System of BALB/c Mice Following Intranasal Infection with a Laboratory Isolate of Chlamydia pneumoniae

Pathology consistent with that observed in Alzheimer’s disease (AD) has previously been documented following intranasal infection of normal wild-type mice with Chlamydia pneumoniae (Cpn) isolated from an AD brain (96-41). In the current study, BALB/c mice were intranasally infected with a laboratory strain of Cpn, AR-39, and brain and olfactory bulbs were obtained at 1-4 months post-infection (pi). Immunohistochemistry for amyloid beta or Cpn antigens was performed on sections from brains of infected or mock-infected mice. Chlamydia-specific immunolabeling was identified in olfactory bulb tissues and in cerebrum of AR-39 infected mice. The Cpn specific labeling was most prominent at 1 month pi and the greatest burden of amyloid deposition was noted at 2 months pi, whereas both decreased at 3 and 4 months. Viable Cpn was recovered from olfactory bulbs of 3 of 3 experimentally infected mice at 1 and 3 months pi, and in 2 of 3 mice at 4 months pi. In contrast, in cortical tissues of infected mice at 1 and 4 months pi no viable organism was obtained. At 3 months pi, only 1 of 3 mice had a measurable burden of viable Cpn from the cortical tissues. Mock-infected mice (0 of 3) had no detectable Cpn in either olfactory bulbs or cortical tissues. These data indicate that the AR-39 isolate of Cpn establishes a limited infection predominantly in the olfactory bulbs of BALB/c mice. Although infection with the laboratory strain of Cpn promotes deposition of amyloid beta, this appears to resolve following reduction of the Cpn antigen burden over time. Our data suggest that infection with the AR-39 laboratory isolate of Cpn results in a different course of amyloid beta deposition and ultimate resolution than that observed following infection with the human AD-brain Cpn isolate, 96-41. These data further support that there may be differences, possibly in virulence factors, between Cpn isolates in the generation of sustainable AD pathology

Analysis of autophagy and inflammasome regulation in neuronal cells and monocytes infected with Chlamydia pneumoniae: Implications for Alzheimer’s disease

Objectives: Our laboratory has been studying the role of infection with the obligate intracellular bacterium Chlamydia pneumoniae in sporadic late-onset Alzheimer disease (LOAD). This infection may be a trigger for the pathology observed in LOAD as a function of initiating changes in gene regulation following entry of the organism into the brain. As such, we are analyzing how this infection can promote changes in autophagy and inflammasome gene regulation as both have been shown to be altered in LOAD. Methods: Human SKNMC neuronal cells and THP1 monocytes were infected in vitro for 24-72 hrs with a laboratory strain of Chlamydia pneumoniae followed by RNA extraction, cDNA synthesis and analysis using Real-Time PCR microarrays for autophagy and inflammasome genes. Results: Gene expression for autophagy and inflammasome pathways was altered dramatically following infection. Genes encoding for co-regulation of autophagy, apoptosis, and the cell cycle that were significantly changed included: BCL2L1, FAS, PIK3CG, APP, and TP53. In addition, ATG3, and GABARAP, genes encoding for protein transport & ubiquitination and autophagic vacuole formation were significantly deregulated. Of the inflammasome genes, 4 NOD-like receptor genes were significantly up-regulated. IL-1beta, AIM2, CCL2, and CCL7 genes were all dramatically up-regulated in monocytes during the 72 hrs of infection. Conclusions: Our data suggest that Chlamydia pneumoniae-infected human SKNMC neuronal cells and THP1 monocytes exhibit specific changes in gene regulation for both autophagy and inflammasome pathways. These gene changes appear to correlate with pathologic changes previously reported in AD and further support the contention that infection with Chlamydia pneumoniae plays a role in LOAD pathogenesis.https://digitalcommons.pcom.edu/posters/1001/thumbnail.jp

Chlamydia pneumoniae: An Etiologic Agent for Late-Onset Dementia

The disease known as late-onset Alzheimer\u27s disease is a neurodegenerative condition recognized as the single most common form of senile dementia. The condition is sporadic and has been attributed to neuronal damage and loss, both of which have been linked to the accumulation of protein deposits in the brain. Significant progress has been made over the past two decades regarding our overall understanding of the apparently pathogenic entities that arise in the affected brain, both for early-onset disease, which constitutes approximately 5% of all cases, as well as late-onset disease, which constitutes the remainder of cases. Observable neuropathology includes: neurofibrillary tangles, neuropil threads, neuritic senile plaques and often deposits of amyloid around the cerebrovasculature. Although many studies have provided a relatively detailed knowledge of these putatively pathogenic entities, understanding of the events that initiate and support the biological processes generating them and the subsequent observable neuropathology and neurodegeneration remain limited. This is especially true in the case of late-onset disease. Although early-onset Alzheimer\u27s disease has been shown conclusively to have genetic roots, the detailed etiologic initiation of late-onset disease without such genetic origins has remained elusive. Over the last 15 years, current and ongoing work has implicated infection in the etiology and pathogenesis of late-onset dementia. Infectious agents reported to be associated with disease initiation are various, including several viruses and pathogenic bacterial species. We have reported extensively regarding an association between late-onset disease and infection with the intracellular bacterial pathoge

Cigarette brands with flavour capsules in the filter: Trends in use and brand perceptions among smokers in the USA, Mexico and Australia, 2012-2014

Objective To describe trends, correlates of use and consumer perceptions related to the product design innovation of flavour capsules in cigarette filters.&nbsp; Methods Quarterly surveys from 2012 to 2014 were analysed from an online consumer panel of adult smokers aged 18&ndash;64, living in the USA (n=6865 observations; 4154 individuals); Mexico (n=5723 observations; 3366 individuals); and Australia (n=5864 observations; 2710 individuals). Preferred brand varieties were classified by price (ie, premium; discount) and flavour (ie, regular; flavoured without capsule; flavoured with capsule). Participants reported their preferred brand variety's appeal (ie, satisfaction; stylishness), taste (ie, smoothness, intensity), and harm relative to other brands and varieties. GEE models were used to determine time trends and correlates of flavour capsule use, as well as associations between preferred brand characteristics (ie, price stratum, flavour) and perceptions of relative appeal, taste and harm.&nbsp; Results Preference for flavour capsules increased significantly in Mexico (6% to 14%) and Australia (1% to 3%), but not in the USA (4% to 5%). 18&ndash;24 year olds were most likely to prefer capsules in the USA (10%) and Australia (4%), but not Mexico. When compared to smokers who preferred regular brands, smokers who preferred brands with capsules viewed their variety of cigarettes as having more positive appeal (all countries), better taste (all countries), and lesser risk (Mexico, USA) than other brand varieties.&nbsp; Conclusions Results indicate that use of cigarettes with flavour capsules is growing, is associated with misperceptions of relative harm, and differentiates brands in ways that justify regulatory action