Increased occurrence of Treponema spp. and double-species infections in patients with Alzheimer's disease.

Although the link between microbial infections and Alzheimer's disease (AD) has been demonstrated in multiple studies, the involvement of pathogens in the development of AD remains unclear. Here, we investigated the frequency of the 10 most commonly cited viral (HSV-1, EBV, HHV-6, HHV-7, and CMV) and bacterial (Chlamydia pneumoniae, Helicobacter pylori, Borrelia burgdorferi, Porphyromonas gingivalis, and Treponema spp.) pathogens in serum, cerebrospinal fluid (CSF) and brain tissues of AD patients. We have used an in-house multiplex PCR kit for simultaneous detection of five bacterial and five viral pathogens in serum and CSF samples from 50 AD patients and 53 healthy controls (CTRL). We observed a significantly higher frequency rate of AD patients who tested positive for Treponema spp. compared to controls (AD: 62.2 %; CTRL: 30.3 %; p-value = 0.007). Furthermore, we confirmed a significantly higher occurrence of cases with two or more simultaneous infections in AD patients compared to controls (AD: 24 %; CTRL 7.5 %; p-value = 0.029). The studied pathogens were detected with comparable frequency in serum and CSF. In contrast, Borrelia burgdorferi, human herpesvirus 7, and human cytomegalovirus were not detected in any of the studied samples. This study provides further evidence of the association between microbial infections and AD and shows that paralleled analysis of multiple sample specimens provides complementary information and is advisable for future studies.

Comparison of a new immunoassay and PCR-based method for quantification of microRNAs in whole blood. A pilot methodical study.

BACKGROUND: MicroRNAs (miRNAs) are new generation biomarkers used in oncology, cardiology, metabolic syndrome, obesity or in neurology. miRNAs are short non-coding RNA molecules that regulate gene expression in eukaryotes. AIM: To compare a new commercial method for establishing miRNA (imunoassay) with a commercial kit RT qPCR. METHODS: RNA was isolated from whole blood samples obtained from four healthy volunteers. The isolates were liquated and miRNA-93-5p and miRNA-23a-3p were measured independently with commercial hsa-miR-93-5p miREIA and hsa-miR-23a-3p miREIA, and commercial RT-qPCR kits. RESULTS: Both miRNAs had good analytical characteristics, very good correlation with RT qPCR. The results between immunoassay and RT qPCR did not statistically differ. A method based on ELISA was faster (2 h with ELISA vs. 3 h with qPCR) and had lower CV then a method based on RT qPCR (see more text). CONCLUSION: MicroRNAs from blood or derived fractions are particularly interesting candidates for routine laboratory applications. The immunoassay can be performed on any device that processes the ELISA plates and is therefore available in almost every laboratory.