Parvimonas micra, an oral pathobiont associated with colorectal cancer, epigenetically reprograms human colonocytes

Recently, an intestinal dysbiotic microbiota with enrichment in oral cavity bacteria has been described in colorectal cancer (CRC) patients. Here, we characterize and investigate one of these oral pathobionts, the Gram-positive anaerobic coccus Parvimonas micra. We identified two phylotypes (A and B) exhibiting different phenotypes and adhesion capabilities. We observed a strong association of phylotype A with CRC, with its higher abundance in feces and in tumoral tissue compared with the normal homologous colonic mucosa, which was associated with a distinct methylation status of patients. By developing an in vitro hypoxic co-culture system of human primary colonic cells with anaerobic bacteria, we show that P. micra phylotype A alters the DNA methylation profile promoters of key tumor-suppressor genes, oncogenes, and genes involved in epithelial-mesenchymal transition. In colonic mucosa of CRC patients carrying P. micra phylotype A, we found similar DNA methylation alterations, together with significant enrichment of differentially expressed genes in pathways involved in inflammation, cell adhesion, and regulation of actin cytoskeleton, providing evidence of P. micra's possible role in the carcinogenic process.

Analysis of ELISA hepatitis C virus-positive blood donors population by polymerase chain reaction and recombinant immunoblot assay (RIBA). Comparison of second and third generation RIBA

A new RIBA-3 (Chiron-Ortho Diagnostic System) was performed for discriminating uninterpretable results of RIBA-2. Recognition of antibodies to hepatitis C virus by RIBA-2 and RIBA-3 was compared among 95 ELISA-2 (second generation ELISA) positive blood donors and correlated with alanine-aminotransferase (ALAT) levels and viremia, using polymerase chain reaction (PCR). These studies led to three important conclusions. First, all ELISA-2-positive, RIBA-2-positive and ALAT-positive samples were found viremic compared with 73% of ELISA-2-positive, RIBA-2-positive and ALAT-negative samples. Then, the comparison of the different RIBAs allowed to conclude that RIBA-3 was more sensitive but less specific than RIBA-2. RIBA-3 was interesting to discriminate undetermined RIBA-2, owing to an improved specificity of C100-3 antigen. In fact, most of the C100-3 positive, RIBA-2 undetermined samples became RIBA-3 negative whereas C22-3 positive, RIBA-2 undetermined samples became RIBA-3 positive or undetermined. Finally, a significant correlation was found between the presence of antibodies against C33-c antigen and viremia.