Researchers at the University of Pennsylvania and TU Dresden have found that trained innate immunity (TRIM) aggravates bone loss in experimental models of periodontitis and inflammatory arthritis. The study, published in Developmental Cell in 2025, challenges the long-held assumption that harnessing innate immune memory is uniformly beneficial. The team, led by George Hajishengallis at Penn Dental Medicine and Triantafyllos Chavakis at TU Dresden, induced TRIM using beta-glucan, a compound found in certain fungi, then measured osteoclast generation in mouse models of both conditions. Beta-glucan primed osteoclast precursors to differentiate more readily when a secondary inflammatory stimulus such as arthritis or periodontitis was introduced. Critically, beta-glucan alone did not cause bone loss; a second inflammatory challenge was required. This mirrors previous work showing beta-glucan can also produce beneficial effects, including tumor growth inhibition, depending on context. The findings indicate that the outcome of TRIM, whether protective or harmful, depends on the inflammatory context in which it occurs, not on the inducing agent itself. For dental professionals, this means that therapeutic strategies targeting trained immunity in periodontal patients may carry risk of unintended bone destruction if concurrent inflammatory conditions are present.