The initial reduction in IL-17F in CF aligns with the slowed bone formation during the initial phase, whereas the increase in IL-17F concentration over 2 years could indicate increases in bone formation following treatment.15 IL-17E suppresses osteoclastogenesis in rheumatoid arthritis.32 The relative increase in IL-17E concentration in CF after treatment compared to the other groups could be due to the need for continued osteogenesis and bone remodeling even after treatment is initiated. Here, IL17F is linked to cystic fibrosis.