Astrocytes Infected with Chlamydia pneumonia Alter Amyloid Processing Implicated in Alzheimer’s Disease

Alzheimer’s Disease (AD) is a chronic, progressive neurodegenerative disease whose pathogenesis centers around the abnormal processing of amyloid precursor protein (APP) by proteases, resulting in the formation of neuritic plaques composed of toxic, insoluble fragments of amyloid protein (Aβ), including Aβ1-40 and Aβ1-42. Previously, our laboratory identified Chlamydia pneumoniae (Cpn) in autopsied sporadic AD brains. Additionally, an infection based animal model was developed using BALB/c mice that were intranasally inoculated with Cpn, in which the deposition of amyloid was consistent with that observed in the human AD brain. These studies have led to the pathogen hypothesis of AD that implicates Cpn as a trigger for the cleavage of APP into Aβ1-40 and Aβ1-42. Objective: Several studies have demonstrated the presence of astrocytes surrounding neuritic plaques within the AD brain; therefore, we speculate that astrocytes may be specifically involved in the pathological processes leading to Aβ deposition. This investigation addresses if an in vitro Cpn infection of human astrocytes affects processing of the ß amyloid precursor protein (ßAPP) and the enzyme ß APP cleaving enzyme-1 (BACE1), a type 1 transmembrane aspartyl protease directly involved in the processing of APP to Aβ and implicated in numerous neurodegenerative diseases, such as traumatic brain injury. Methods: Human astrocytes (CCF-STTG1) were infected in vitro with the respiratory strain AR39 Cpn (MOI=1). Analysis of protein levels for Aβ and the enzyme BACE1 post-infection was detected by immunocytochemistry and captured with the Olympus Confocal FV1000 microscope. Results: Amyloid processing in infected astrocytes was altered relative to that of uninfected astrocytes. BACE1 immunolabeling appeared more diffuse in the infected astrocytes as compared to membrane-localized BACE1 in the uninfected astrocytes. Conclusions: Neurons have been presumed to be the primary source of beta-amyloid peptides in AD brains; however, when astrocytes are activated, as occurs during infection with Cpn, astrocytic beta-amyloid generation may contribute to amyloid plaque formation. These data imply that infection of human astrocytes with Cpn affects the processing of ßAPP through altering the localization of BACE1 protein from the membrane to the cytoplasm. These data suggest an activation of BACE1 in the processing of amyloid by astrocytes as a major contributor to the neurotoxic amyloid deposition linked to pathology observed in AD

Chlamydia pneumoniae infection of neuronal cells induces changes in calcium-associated gene expression consistent with Alzheimer’s disease

Background and Significance: Previous studies have shown that cells infected with Chlamydia pneumoniae (Cpn) exhibit altered gene expression consistent with that observed in Alzheimer’s disease (AD). Furthermore, AD neurodegeneration has been linked to dysregulation of intracellular calcium and calcium-related processes. Therefore, we hypothesize that one mechanism by which pathogenesis evolves in AD is through infection-induced changes in expression of calcium-related genes. Objectives: To determine if infection of neuronal cells with Cpn alters expression of calciumrelated genes associated with neurodegeneration. Methods: SK-N-MC neuronal cells were infected with Cpn (AR39 strain; MOI=1) for 3 to 72 hours, then calcium-related genes were screened with real-time PCR microarrays (SABiosciences PAHS-066). Results: Following infection, approximately 29 genes displayed regulation changes of 2-fold or greater, including genes pertaining to neurotransmitters, cell cycle and immune regulators, and other calcium-responsive elements. Genes involved in synaptic function and memory such as AREG, ATF3, EGR2 and GEM were initially up regulated, then fell to baseline or below by 72 hours. Many of the affected genes have been implicated in AD pathogenesis. Conclusions: Our data suggest that Cpn alters calcium-related gene expression in host neurons consistent with calcium dysfunction previously documented in AD. This study may elucidate how, in its effort to establish a favorable environment, Cpn could affect cellular processes that contribute to AD pathogenesis.https://digitalcommons.pcom.edu/posters/1006/thumbnail.jp

Assessment of the impact of race and proxies of socioeconomic status on the prevalence and health outcome of peripartum cardiomyopathy (PPCM) using the “All of Us” Databank

Background: Peripartum Cardiomyopathy (PPCM) is a form of cardiomyopathy occurring during the last month of pregnancy or within months after giving birth in women with previously normal hearts. PPCM is an idiopathic systolic dysfunction that causes a reduced left ventricle ejection fraction. The estimated incidence of PPCM worldwide is 1 diagnosis out of 2,000 live births, and the causes of PPCM remain unknown. A retrospective cohort study conducted at the University of Pennsylvania Health System by Getz et al. showed that black race and socioeconomic proxies (like neighborhood disadvantage index (NDI)) were independently associated with sustained cardiac dysfunction (Getz et al., Am Heart J 2021). This study also showed that from all the components of NDI (education, high rental occupied housing, annual income below poverty line, female headed household, adults unemployed, adults on public assistance), low education and high rental occupied housing were significantly associated with sustained cardiac dysfunction. The central aim of the present project is to assess the effect of socioeconomic proxies (including NDI, lack of access to health care and food insecurity) on the prevalence of sustained cardiac dysfunction from PPCM across the US using the “All of Us” databank. A secondary aim is to test the compliance of the All of Us database capacity to interrogate this potential association. Lastly, we aim to compare the results obtained from the All of Us database with the UK Biobank. Methods: The All of Us databank (Ramirez et al., Patterns 2022; The All of US Research Program, NEJM 2019) will be used to conduct a retrospective cohort study to assess how proxies of socioeconomic status may affect the incidence and prevalence of sustained cardiac dysfunction from PPCM across different ethnicities in the US. The All of Us database focuses on enrolling people in the US from diverse groups that have historically been underrepresented in medical research. Therefore, it includes a more diverse population than the population targeted in the retrospective study conducted at the University of Pennsylvania in which only black women from Philadelphia, PA, were included. To further interrogate the impact that geographic location and population ethnicity may have on the prevalence of sustained cardiac dysfunction from PPCM, the results obtained from the “All of Us” database will be compared against data obtained from the UK Biobank. Expected Results: We expect that the socioeconomic proxies interrogated in this study will have a significant impact on the prevalence of sustained cardiac dysfunction from PPCM. Current knowledge is limited on how socioeconomic status affects sustained cardiac dysfunction resulting from PPCM. Previous studies have been done on populations restricted to small geographic areas and did not analyze factors such as food security, access to care, or disability status. Understanding how these factors affect the incidence and prevalence of sustained cardiac dysfunction from PPCM may be used to improve prevention, early diagnosis, and management of PPCM

Minimally Invasive In Vivo Real-Time Identification of Human Astrocytoma with Sulforhodamine 101

Abstract and poster under embargo until May 31, 2019

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-Infected Astrocytes Alter Their Expression of ADAM10, BACE1, and Presenilin-1 Proteases

Background: Utilizing β-amyloid precursor protein (βAPP) as a substrate, α-, β-, and γ-secretases are responsible for sequential cleavage events leading to the formation of β-amyloid, the classic pathologic hallmark of Alzheimer\u27s Disease. Members of this class of proteases also catalyze the activation of numerous other membrane- localized proteins implicated in cell growth and neuroinflammation such as NOTCH and the Interleukin/TNF-receptor family, respectively. This investigation addresses if an in vitro Chlamydia pneumoniae infection of human astrocytes affects the processing of βAPP through modifying the protein expression of the following βAPP processing proteases: A Disintegrin and Metalloproteinase- 10 (ADAM10), βAPP cleaving enzyme-1 (BACE1), and presenilin- 1 (PSEN1). Methods: Human astrocytoma cells (CCF-STTG1) were infected in vitro with Chlamydia pneumoniae strain AR39 (MOI=1). At 6-72 hours post infection, protein level of β-amyloid, ADAM10, BACE1, and presenilin-1 N-terminal fragment (NTF) relative to uninfected controls were detected by immunofluorescence and quantified by western blot analysis. Results: Cytoplasmic labeling of Aβ1-42 was increased in infected cells relative to that of uninfected cells. Membrane-localized labeling of BACE1 and cytoplasmic labeling of PSEN1 NTF was also enhanced at earlier (6 hrs.) and later (48/72 hrs.) time points post infection relative to that of uninfected astrocytes. Increases in quantified BACE1 and PSEN1, but not ADAM10, followed a similar temporal increase most notable at 48 hrs. post infection. Conclusions: These data indicate that infection of human astrocytes with Chlamydia pneumoniae strain AR39 promotes the processing of βAPP characteristic of Alzheimer\u27s Disease through enhancing BACE1 and PSEN1, but not ADAM10, protein levels. Increases in active secretase protein may coincide with the 24-48 hr. lifecycle of Chlamydial intracellular growth and replication and the consequent astrocytic inflammatory response

Modulation of N-cadherin junctions and their role as epicenters of differentiation-specific actin regulation in the developing lens

AbstractExtensive elongation of lens fiber cells is a central feature of lens morphogenesis. Our study investigates the role of N-cadherin junctions in this process in vivo. We investigate both the molecular players involved in N-cadherin junctional maturation and the subsequent function of these junctions as epicenters for the assembly of an actin cytoskeleton that drives morphogenesis. We present the first evidence of nascent cadherin junctions in vivo, and show that they are a prominent feature along lateral interfaces of undifferentiated lens epithelial cells. Maturation of these N-cadherin junctions, required for lens cell differentiation, preceded organization of a cortical actin cytoskeleton along the cells' lateral borders, but was linked to recruitment of α-catenin and dephosphorylation of N-cadherin-linked β-catenin. Biochemical analysis revealed differentiation-specific recruitment of actin regulators cortactin and Arp3 to maturing N-cadherin junctions of differentiating cells, linking N-cadherin junctional maturation with actin cytoskeletal assembly during fiber cell elongation. Blocking formation of mature N-cadherin junctions led to reduced association of α-catenin with N-cadherin, prevented organization of actin along lateral borders of differentiating lens fiber cells and blocked their elongation. These studies provide a molecular link between N-cadherin junctions and the organization of an actin cytoskeleton that governs lens fiber cell morphogenesis in vivo