Differential inducibility of transmembrane peptidoglycan recognition proteins (PGRPs) by bacterial challenges in the earthworm, Eisenia andrei.

Peptidoglycan recognition proteins (PGRPs) and Toll-like receptors (TLRs) are highly conserved pattern recognition receptors (PRRs). Earthworms possess genes encoding TLRs that specifically respond to Gram-positive bacteria. In addition, several PGRPs have been recently identified, which are predicted to exhibit amidase activity but lack receptor function. In lophotrochozoans, a membrane-bound PRR responsible for detecting Gram-negative bacteria remains unidentified. This study reveals several novel transmembrane peptidoglycan recognition proteins (Ean-PGRPLs) in earthworms, whose mRNA expression increases in response to Gram-negative but not Gram-positive bacteria. This indicates that Ean-PGRPLs may serve as a PRR associated with intracellular signaling for Gram-negative bacteria.

Colorectal cancer diagnostic model utilizing metagenomic and metabolomic data of stool microbial extracellular vesicles.

Colorectal cancer (CRC) is the most common type cancers in the world. CRC occurs sporadically in the majority of cases, indicating the predominant cause of the disease are environmental factors. Diet-induced changes in gut-microbiome are recently supposed to contribute on epidemics of CRC. This study was aimed to investigate the association of metagenomics and metabolomics in gut extracellular vesicles (EVs) of CRC and healthy subjects. A total of 40 healthy volunteers and 32 patients with CRC were enrolled in this study. Metagenomic profiling by sequencing 16 S rDNA was performed for assessing microbial codiversity. We explored the small molecule metabolites using gas chromatography-time-of-flight mass spectrometry. In total, stool EVs were prepared from 40 healthy volunteers and 32 patients with CRC. Metagenomic profiling demonstrated that bacterial phyla, particularly of Firmicutes and Proteobacteria, were significantly altered in patients with colorectal cancer. Through metabolomics profiling, we determined seven amino acids, four carboxylic acids, and four fatty acids; including short-chain to long chain fatty acids that altered in the disease group. Binary logistic regression was further tested to evaluate the diagnostic performance. In summary, the present findings suggest that gut flora dysbiosis may result in alternation of amino acid metabolism, which may be correlated with the pathogenesis of CRC.