Which interleukin plays the most significant role in the pathogenesis of periodontitis?

Correct answer: D. Interleukin-1 (IL-1)

• A. IL-4 is an anti-inflammatory cytokine that promotes Th2 responses and B-cell class switching; it plays a regulatory role, not a pathogenic one in periodontitis.
• B. IL-10 is an anti-inflammatory cytokine that downregulates inflammation; elevated IL-10 is associated with chronic, stable periodontitis — not its pathogenesis.
• C. IL-13 is involved in allergic inflammation and fibrosis (Th2 pathway); it is not a primary driver of periodontitis.
• D. Correct. IL-1β (along with TNF-α and PGE2) is the primary pro-inflammatory cytokine driving alveolar bone resorption in periodontitis. It stimulates osteoclast activity and matrix metalloproteinase production.