Identification of Candidate Adherent-Invasive E. coli Signature Transcripts by Genomic/Transcriptomic Analysis

Area of Science:

• Microbiology
• Genomics
• Gastroenterology

Background:

• Adherent-invasive Escherichia coli (AIEC) are frequently found in Crohn's disease (CD) lesions.
• AIEC exhibits adherence, invasion of intestinal cells, and intracellular survival within macrophages.
• Accurate identification of AIEC is crucial for understanding CD pathogenesis.

Purpose of the Study:

• To identify candidate transcripts distinguishing AIEC from non-invasive E. coli (NIEC).
• To explore potential culture-independent methods for AIEC identification.
• To uncover genetic signatures associated with AIEC in inflammatory bowel disease.

Main Methods:

• Comparative RNA-Sequence (RNASeq) analysis of AIEC strain LF82 and NIEC strain HS.
• Differential gene expression analysis during exponential and stationary growth phases.
• In silico subtractive genomics to identify AIEC-specific genes.
• Reverse transcription quantitative polymerase chain reaction (RT-qPCR) on patient samples.

Main Results:

• Significant differential expression of genes related to transition metal transport, siderophore metabolism, glycogen metabolism, and oxidation-reduction pathways in AIEC.
• Identification of 747 AIEC-specific coding sequences (CDS) and 166 CDS lacking homology in NIEC strains.
• Discovery of CRISPR-associated (Cas) gene loci and pdu operon genes enriched in AIEC.
• Higher expression of Cas loci in fecal and ileal RNA from CD patients compared to non-IBD controls.

Conclusions:

• Comparative genomic and transcriptomic approaches can identify AIEC signature transcripts.
• CRISPR-associated (Cas) genes show potential as biomarkers for AIEC in CD.
• These findings support the development of rapid, culture-independent AIEC detection methods.