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Distinct anal microbiome is correlated with anal cancer precursors in MSM with HIV

Cristina E Brickman1, Melissa Agnello2,3, Nabeel Imam4,5

  • 1University of California.

AIDS (London, England)
|May 1, 2024
PubMed
Abstract

Insights

The anal microbiome differs from stool in men who have sex with men with HIV. A pro-inflammatory anal microbiome is linked to high-grade squamous intraepithelial lesions (HSIL), a precursor to anal cancer.

Area of Science:

  • Microbiology
  • Gastroenterology
  • Oncology

Background:

  • Anal cancer risk is higher in men who have sex with men with HIV (MSMWH).
  • High-risk human papillomavirus (hr-HPV) infection is necessary but not sufficient for anal cancer precursor lesions (HSIL).
  • Additional factors likely contribute to HSIL development in MSMWH.

Purpose of the Study:

  • To compare the anal canal microbiome with the stool microbiome in MSMWH.
  • To investigate associations between anal microbiome alterations and HSIL in MSMWH.

Main Methods:

  • Cross-sectional study comparing anal and stool microbiomes in MSMWH.
  • Anal samples collected via sterile swabs; stool samples mailed from home.
  • 16S rRNA sequencing for bacterial identification; diversity and differential abundance analyses performed.

Main Results:

  • Anal and stool microbiomes showed distinct clustering.
  • Among hr-HPV-positive MSMWH, 31 had HSIL and 13 did not.
  • HSIL was associated with increased pro-inflammatory/carcinogenic bacteria (e.g., Prevotella, Fusobacterium) and decreased anti-inflammatory bacteria (e.g., Anaerostipes caccae).

Conclusions:

  • The anal microbiome is significantly different from the stool microbiome.
  • A pro-inflammatory and potentially carcinogenic anal microbiome environment may be associated with anal HSIL in MSMWH.

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