Purpose of review
Inflammatory bowel disease (IBD) is associated with bone loss leading to osteoporosis and increased fracture risk. Bone loss is the result of changes in the balanced process of bone remodeling. Immune cells and cytokines play an important role in the process of bone remodeling and it is therefore not surprising that cytokines as observed in IBD are involved in bone pathology. This review discusses the role of cytokines in IBD-associated bone loss, including the consequences for treatment.
Many studies have been conducted that showed the effect of a single cytokine on bone cells in vitro, including interleukin (IL)-1β, IL-6, IL-8, IL-12/IL-23, IL-17, IL-18, IL-32 and interferon-γ. Recently new members of the IL-1 family (IL-1F) have been related to IBD but the consequences for bone health remain uncertain.
Overall, patients have to deal with a cocktail of cytokines, present in their serum. The combination of cytokines can affect bone cells differently compared to the effects of a single cytokine. This implicates that treatment, focused on reducing the inflammation could work best for bone health as well. Vitamin D might also play a role in this.