Adipose tissue microbiota in humans: an open issue.

Area of Science:

• Microbiology
• Human Physiology
• Metagenomics

Background:

• A specific microbiota in adipose tissue has been identified in mice and suggested in humans.
• Investigating the presence of microbiota in human adipose tissue is crucial for understanding host-microbe interactions.

Purpose of the Study:

• To determine if human whole adipose tissue and isolated adipocytes harbor a microbiota.
• To employ both culture-dependent and independent methods for comprehensive analysis.

Main Methods:

• Utilized standard microbiological culturing and 16S ribosomal RNA (16S rRNA) gene sequencing (Illumina).
• Analyzed DNA and RNA from whole subcutaneous and visceral adipose tissue (SAT/VAT) and isolated adipocytes.
• Optimized bacterial 16S rRNA gene detection using various DNA extraction and PCR amplification techniques.

Main Results:

• Microbiological cultures yielded negative results across all samples.
• Enzymatically isolated adipocytes showed bacterial DNA primarily from Clostridium histolyticum, the source of collagenase.
• Bacterial 16S rRNA gene was undetectable in whole adipose tissue and mechanically isolated adipocytes, even after blocking human mitochondrial 12S rRNA amplification.

Conclusions:

• The study's findings do not support the existence of a human adipose tissue microbiota.
• Highlighted significant technical challenges in metagenomic studies of human tissues with minimal or absent bacterial presence.