The Toll of Cathepsin K Deficiency

摘要

Cathepsins are lysosomal proteases that cleave their substrates with relatively low specificity. Cathepsins L and S process antigens for presentation to T cells, and are thus critical for developing adaptive immunity and long-lasting protection from specific pathogens (1). However, no cathepsin had been known to participate in innate immunity, a more general and nonspecific response to infection. On page 624 in this issue, Asagari et al. (2) reveal that cathepsin K, known for its importance in bone resorp-tion, is important in the innate immune response to pathogen DNA. This presents an interesting example of molecules and mechanisms that are shared between the skeletal and immune systems, and raises the issue of whether treatment of conditions in one system could affect functions of the other.