A Unique Gut Microbiome-Physical Function Axis Exists in Older People with HIV: An Exploratory Study

Area of Science:

• Microbiology
• Gerontology
• Immunology

Background:

• Older persons with HIV (PWH) often experience impaired physical function and elevated inflammation.
• Previous research indicated differing gut microbiota-inflammation associations based on HIV status in older adults.
• The gut microbiome's role in physical function disparities between PWH and controls requires further investigation.

Purpose of the Study:

• To investigate distinct relationships between the gut microbiome and physical function in older PWH versus age-matched uninfected controls.
• To analyze associations between gut bacteria and short-chain fatty acid (SCFA) levels with physical function and body composition.

Main Methods:

• Reanalysis of existing gut microbiome and SCFA data from older, nonfrail PWH on antiretroviral therapy and uninfected controls.
• Correlation analysis using HIV-adjusted linear regression models between bacterial relative abundance (RA) or SCFA levels and physical function/body composition metrics.
• Assessment of physical function using measures like grip strength and the Short Physical Performance Battery (SPPB).

Main Results:

• In older PWH, increased RA of specific bacteria (e.g., *Alistipes*, *Escherichia*) correlated with reduced muscle function, lean mass, and SPPB scores.
• Conversely, higher RA of other bacteria (e.g., *Dorea*, *Coprococcus*) in PWH was linked to better muscle function, lean mass, and SPPB scores.
• Elevated butyrate levels were associated with increased grip strength in both PWH and controls.

Conclusions:

• The gut microbiome exhibits both detrimental and beneficial associations with physical function in older PWH.
• These gut-microbiome-physical function relationships differ significantly between older PWH and their uninfected counterparts.
• Findings suggest a unique gut-physical function axis specific to people with HIV.