Cytological and cytometric analysis of oral mucosa in patients with Alzheimer's and Parkinson's disease

Biomarkers in Alzheimer's disease

Alzheimer's disease (AD) is among the most common neurodegenerative disorders. AD is characterized by deposition of neurofibrillary tangles and amyloid plaques, leading to associated secondary pathologies, progressive neurodegeneration, and eventually death. Currently used diagnostics are largely image-based, lack accuracy and do not detect early disease, ie, prior to onset of symptoms, thus limiting treatment options and outcomes. Although biomarkers such as amyloid-β and tau protein in cerebrospinal fluid have gained much attention, these are generally limited to disease progression. Unfortunately, identification of biomarkers for early and accurate diagnosis remains a challenge. As such, body fluids such as sweat, serum, saliva, mucosa, tears, and urine are under investigation as alternative sources for biomarkers that can aid in early disease detection. This review focuses on biomarkers identified through proteomics in various biofluids and their potential for early and accurate diagnosis of AD.

Oral Mucosa Derived α−Synuclein as a Potential Diagnostic Biomarker for Parkinson′s Disease

Background

Pathological α-synuclein (α-Syn) is not only exclusive to the central nervous system (CNS) in Parkinson’s disease (PD), but also extended to biofluids and peripheral tissues including oral cavity. Both oral mucosa and nervous system are derived from ectodermal tissue, and potentially share common disease-specific characteristics. Oral mucosal exfoliative cytology is a non-invasive technique, which is an easily acceptable for patients and ordinary people. The purpose of this study was to determine the abnormal accumulation of α-Syn in oral mucosa of PD patients and to learn the diagnostic utility of oral mucosa α-Syn for PD.

Methods

The oral mucosa samples were obtained from 57 patients with PD and 51 age-matched controls by cytological brush. Immunofluorescence analysis was used to investigate the presence and subcellular localization of α-Syn, phosphorylated α-Syn at Ser129 (pS129) and oligomeric α-Syn in the oral mucosa cells of PD patients and controls. Images taken as Z-stacks were analyzed for 3D reconstruction to visualize the α-Syn intracellular localization. Then, the concentrations of α-Syn, pS129, and oligomeric α-Syn in oral mucosa samples were measured using electrochemiluminescence assays.

Results

Immunofluorescence images revealed the increased α-Syn, pS129, and oligomeric α-Syn levels in oral mucosa cells of PD patients than age-matched controls. The intracellular distributions of α-Syn species were determine by Z-stack images with 3D reconstruction, and α-Syn was detected in both the nucleus and cytoplasm. However, pS129 was mainly located in the cytoplasm, and oligomeric α-Syn was highly expressed in the nucleus and perinuclear cytoplasm. The concentrations of three α-Syn species were significantly increased in the oral mucosa cell samples of PD patients than controls (α-Syn, p = 0.001; pS129, p = 0.002; oligomeric α-Syn, p = 0.013). In PD patients, the oral mucosa α-Syn and oligomeric α-Syn levels were significantly correlated with Hoehn-Yahr scales (α-Syn, r = 0.495, p = 0.001; oligomeric α-Syn, r = 0.324, p = 0.03). The area under curve (AUC) of ROC analysis using an integrative model including α-Syn, pS129, and oligomeric α-Syn for PD diagnosis was 0.749, with 66.7% sensitivity and 72.5% specificity.

Conclusion

This study for the first time demonstrated increased expressions of α-Syn, pS129, and oligomeric α-Syn in oral mucosa cells from PD patients, which serve as useful and non-invasive PD diagnostic biomarkers.

Impact of preterm birth on the cellular characteristics of neonatal buccal cells

OBJECTIVE

To demonstrate the impact of preterm birth on the cytological, cytomorphometrical, and nuclear parameters of neonatal buccal smears.

METHODS

This study consisted of Early Preterm Neonates (EPN; ≤34th gestational week [gw]; n = 36), Late Preterm Neonates (LPN; 34th to <37th gw; n = 46), and Term Neonates (control; ≥37th gw; n = 56). Cytological evaluation and buccal cytome assay were performed using Papanicolaou and Feulgen methods, respectively.

RESULTS

Cytological evaluation demonstrated that smear background was cleaner (P < .05) and there were less macrophages in the control group (P < .001). Cyto-morphometric analysis showed that the measurements of nuclear diameter, nuclear area, and nucleus-to-cytoplasm ratio were higher in the preterm (EPN and LPN) versus the control groups (P = .016, P < .001, and P < .001, respectively). We also demonstrated that staining intensity of the nucleus and cytoplasm were less intense in the EPN and LPN groups (P < .001). There was no statistically significant difference between the EPN and LPN groups for any parameters (P > .05). Buccal cytome assay showed that nuclear buds were more prevalent in term newborns compared to preterm neonates (P < .001).

CONCLUSIONS

Morphological and cytological properties of neonatal buccal cells are influenced by preterm birth status, and buccal smears may be used as a tool to detect biological markers of neonatal health problems.

Genome-Scale Expression Pattern of Long Non-Coding RNAs in Chinese Uyghur Patients with Parkinson's Disease

BACKGROUND Long non-coding RNAs (lncRNAs) are transcripts thought to regulate gene expression at the post-transcriptional level. Some lncRNAs are associated with Parkinson's disease (PD) and participate in pathological processes of PD. The incidence of PD is relatively high in members of the Uyghur minority living in Xingjiang province of China. This study measured the expression of lncRNAs in the peripheral blood cells of Chinese Uyghur individuals with and without PD and analyzed the possible function of these lncRNAs in the development of PD. MATERIAL AND METHODS Peripheral blood samples were collected from 55 Uyghur patients with PD and 55 healthy volunteers. Total RNA was extracted, and the levels of expression of whole-genome lncRNAs and mRNAs in 10 samples (5 PD and 5 controls) were determined by microarray method. The expression levels of lncRNAs in all 100 subjects were determined by qRT-PCR. The lncRNA expression profiles of PD patients were determined based on lncRNA microarray chip analysis, and differentially expressed lncRNAs were identified. The results of chip analysis were confirmed in a large clinical cohort. RESULTS Comparison of subjects with and without PD identified 32 significantly up-regulated and 18 significantly down-regulated lncRNAs in the PD group. GO analysis showed that mRNAs encoding proteins involved in the regulation of biological processes were differentially expressed, with the inflammatory immune response being the most significantly related pathway. CONCLUSIONS The expression of lncRNAs in peripheral blood differed significantly in PD patients and controls. These differentially expressed lncRNAs may play a role in the development of PD.

Diagnostic Biomarkers for Alzheimer's Disease Using Non-Invasive Specimens

Studies in the field of Alzheimer’s disease (AD) have shown the emergence of biomarkers in biologic fluids that hold great promise for the diagnosis of the disease. A diagnosis of AD at a presymptomatic or early stage may be the key for a successful treatment, with clinical trials currently investigating this. It is anticipated that preventative and therapeutic strategies may be stage-dependent, which means that they have a better chance of success at a very early stage—before critical neurons are lost. Several studies have been investigating the use of cerebrospinal fluid (CSF) and blood as clinical samples for the detection of AD with a number of established core markers, such as amyloid beta (Aβ), total tau (T-tau) and phosphorylated tau (P-tau), being at the center of clinical research interest. The use of oral samples—including saliva and buccal mucosal cells—falls under one of the least-investigated areas in AD diagnosis. Such samples have great potential to provide a completely non-invasive alternative to current CSF and blood sampling procedures. The present work is a thorough review of the results and analytical approaches, including proteomics, metabolomics, spectroscopy and microbiome analyses that have been used for the study and detection of AD using salivary samples and buccal cells. With a few exceptions, most of the studies utilizing oral samples were performed in small cohorts, which in combination with the existence of contradictory results render it difficult to come to a definitive conclusion on the value of oral markers. Proteins such as Aβ, T-tau and P-tau, as well as small metabolites, were detected in saliva and have shown some potential as future AD diagnostics. Future large-cohort studies and standardization of sample preparation and (pre-)analytical factors are necessary to determine the use of these non-invasive samples as a diagnostic tool for AD.

GDF-15 promotes mitochondrial function and proliferation in neuronal HT22 cells

The neuronal cell line HT22 is an excellent model for studying Parkinson's disease. Growth differentiation factor 15 (GDF15) plays a critical role in Parkinson's disease, but the molecular mechanism involved are not well understood. We constructed the GDF15 overexpression HT22 cells and detected the effects of overexpression of GDF15 on the viability, oxygen consumption, mitochondrial membrane potential of oligomycin-treated HT22 cells. In addition, we used a high-throughput RNA-sequencing to study the lncRNA and mRNA expression profiling and obtained key lncRNAs, mRNA, gene ontology (GO), and Kyoto encyclopedia of genes and genomes (KEGG) pathway. The expression of selected DElncRNAs was validated by quantitative real-time PCR (qRT-PCR). Our results showed that overexpression of GDF15 significantly reversed the cells viability, oxygen consumption, and mitochondrial membrane potential effect caused by oligomycin in HT22 cells. The 1093 DEmRNAs and 395 DElncRNAs in HT22 cells between GDF15-oligomycin non-intervention group and a normal control-oligomycin un-intervention group were obtained, and 394 DEmRNAs and 271 DElncRNAs in HT22 cells between GDF15-oligomycin intervention group and normal control-oligomycin intervention group were identified. Base on the GO and KEGG enrichment analysis of between GDF15-oligomycin intervention group and normal control-oligomycin intervention group, positive regulation of cell proliferation was most significantly enriched GO terms, and Cav1 was enriched in positive regulation of cell proliferation pathway. PI3K-Akt signaling pathway was one significantly enriched pathway in GDF15-oligomycin intervention group. The qRT-PCR results were consistent with RNA-sequencing, generally. GDF15 might promote mitochondrial function and proliferation of HT22 cells by regulating PI3K/Akt signaling pathway. Our study may be helpful in understanding the potential molecular mechanism of GDF15 in Parkinson's disease.