BB-TL1A-VIAL-HLE

The goal of this clinical trial is to learn if BB-TL1A-VIAL-HLE is safe in healthy adults and is safe and effective in treating adults with moderate-to-severe ulcerative colitis. The main questions it aims to answer are:
Is the intervention safe in healthy adults and in adults with moderate-to-severe ulcerative colitis? Is the intervention effective in treating adults with moderate-to-severe ulcerative colitis? Researchers will compare the Phase 1b arm to a historical treatment arm to see if the study drug is at least as effective as a relevant benchmark.
Participants will:
* Attend the clinical research site several times over the course of
1 year
* Have blood and urine samples taken
* Undergo physical examinations
* Receive one injection of the study drug