Role of different Microorganisms in Parkinson's Disease, Rheumatoid Arthritis, and Colorectal Cancer

Abstract: In this work the role of microorganisms in three non-communicable diseases (NCDs) among others were investigated: Parkinson's disease (PD), Rheumatoid arthritis (RA) and Colorectal Cancer (CRC). RA. Polyclonal IgG antibodies (Abs) specific for peptides derived from Porphyromonas gingivalis, Pg (RgpA, Kpg); Aggregatibacter actinomycetemcomitans, Aa (LtxA1, LtxA2); Mycobacterium avium subsp. Paratuberculosis, MAP (MAP4027); Epstein-Barr virus, EBV (EBNA1, EBVBOLF) and human endogenous retrovirus, HERV (HERV-W env-su) were detected by indirect ELISA in serum samples from 148 consecutive RA patients and 148 sex and age-matched healthy controls (HCs). RA patients exhibit a higher prevalence of humoral immune response against all tested peptides compared to HCs with a statistically significant difference for MAP4027 (30.4% vs. 10.1%), BOLF (25.7% vs. 8.1%), RgpA (24.3% vs. 9.4%), HERV W-env (20.3% vs. 9.4%), and EBNA1 (18.9% vs. 9.4%) peptides. This study demonstrated a significantly increased humoral response against multiple pathogens in patients with RA and implies that they could be important factors in the pathogenesis of the disease. PD. In addition, in this thesis Abs response against the following peptides from Herpes Simplex virus 1, HSV-1 (UI4222-36), human α-synuclein (α-syn100-114), Porphyromonas gingivalis, Pg (RgpA800-812, Kpg328-339), Aggregatibacter actinomycetemcomitans, Aa (LtxA1429-445, LtxA264-80) and bacterial curli (Curli133-141) were investigated by indirect ELISA in 51 serum samples from PD and 58 sex and age-matched HCs. Significant differences in OD (optical density) values and Abs positivity between PD patients and HCs were observed for Kpg (82.3% vs. 10.3%), followed by RgpA (60.7% vs. 24.1%), curli (51% vs. 22.4%), and UI42 (43.1% vs. 25.8%) in PD, compared to HCs sera (p < 0.001). Significant positive correlations between OD values obtained by ELISA were observed for UI42 and curli (r = 0.811, p < 0.0001) and Kpg and RgpA (r = 0.659, p < 0.0001). This study reports a significantly increased humoral response against curli, Pg, and HSV-1 in PD patients, implying that they could be important factors in the pathogenesis of the disease. CRC. In the first part of the CRC study, thirty-one CRC tissue biopsies and thirty-one normal colorectal tissue biopsies were recruited. Bacteroides fragilis isolation, phenotypic and PCR identification tests were performed. Furthermore, biofilm-forming ability and expression of bft gene were assessed under biofilm and planktonic forms. A total of 62 B. fragilis strains were isolated from all colorectal tissue, of which 13 isolates (20.96%) (11 isolates from CRC and 2 from normal tissue) were positive for bft gene. Moreover, toxin-producing B. fragilis strains showed higher biofilm formation ability compared to non-toxigenic B. fragilis strains. Toxin expression was significantly reduced in biofilm form compared with planktonic form living bacteria. Finally, the number of toxin-producing B. fragilis strains and their biofilm formation ability were significantly higher in CRC patients in compared with HCs. In the second part of study, 40 saliva and 40 fecal samples were collected from 20 CRC stage 0 and I patients and 20 HCs. 16s rRNA sequencing assays was performed to study microbiota profiles in all oral and fecal samples. Bifidobacterium was identified as a potential bacterial biomarker in CRC saliva samples, while Fusobacterium, Dialister, Catonella, Tennerella, Eubacteriumbrachy-group, and Fretibacterium were ideal to distinguish HCs from CRC patients. Moreover, an evaluation of saliva microbiota might offer a suitable screening test for the early detection of this malignancy, providing more accurate results than its fecal counterpart.