Challenging the opinion that SAPHO syndrome is associated with low intracellular ROS production in neutrophils

Background SAPHO syndrome, characterized by synovitis, acne, pustulosis, hyperostosis, and osteitis, belongs to the autoinflammatory bone disorders, in which dysregulation of innate immunity typically causes inflammation in sterile bone. The mechanisms underlying SAPHO syndrome are unknown, but neutrophil activation is suggested as part of disease pathophysiology. Previously, a patient with SAPHO syndrome-like phenotype was shown to lack production of intracellular NADPH-oxidase-derived reactive oxygen species (ROS) in response to phorbol myristate acetate (PMA; Ferguson et al, Arthritis and Rheumatism, 2008). In absence of phagosome-formation, such ROS are produced in intracellular granules, and are suggested to be part of regulatory signaling associated with hyperinflammatory disease.