Tumor necrosis factor-alpha (TNF-alpha) inhibitors, such as Infliximab and Adalimumab, act as a brake on the immune system. They are vital in treating autoimmune diseases like rheumatoid arthritis and Crohn's disease by reducing excessive inflammation. These inhibitors curb the effects of TNF-alpha, a pro-inflammatory molecule, helping manage symptoms and improve the quality of life for individuals battling these conditions.