The study explores the effects of a medicine called doxycycline on inflammation and bacteria in the body, particularly for people with HIV and those using HIV pre-exposure prophylaxis (PrEP). Doxycycline is a drug approved by the FDA for treating bacterial infections. Researchers want to see if it helps with inflammation or impacts the bacteria living in our bodies when used for sexually transmitted infections (STIs) as post-exposure prophylaxis (PEP).

Participants should be healthy males, aged 18 or older, and either living with HIV or using PrEP. The study runs for about 12 weeks, requiring five visits, each lasting 45 minutes to 1 hour, with two involving biopsies (a procedure where a small sample of tissue is taken).

During the study, medical history and biological samples, like blood and rectal tissue, will be collected.

• Study duration is 12 weeks with five visits.
• Participants must be healthy males, 18+ years old.
• Involves blood and tissue sample collection, including biopsies.