A 52-year-old woman presents with a 2-month history of progressive joint pain and stiffness. She reports morning stiffness lasting well over an hour and symmetrical pain in her proximal interphalangeal and metacarpophalangeal joints of both hands. On examination, there is swelling, warmth, and reduced range of motion in these joints, as well as firm subcutaneous nodules over her extensor surfaces. Laboratory studies reveal a positive rheumatoid factor and elevated anti–cyclic citrullinated peptide (anti-CCP) antibody levels. Radiographs demonstrate joint space narrowing and marginal erosions. Which of the following pathologic processes is most directly responsible for the bone and cartilage destruction in this patient’s joints?