Comparison of Human IL-11 and PTH: Effect on Blood and Bone Parameters in Adult Ovariectomized Mice.

Interleukin-11 (IL-11) is a multi-functional cytokine with effects on hematopoiesis and bone remodeling. IL-11 is known to promote osteoclast formation by RANKL-dependent and independent processes. Recently, it was reported that IL-11 receptor signaling is required for normal bone turnover. To understand recombinant human IL-11 (rhuIL-11) effects on bone remodeling in vivo, we compared rhuIL-11 and PTH treatment in adult ovariectomized mice. IL -11 or PTH was administered s.c. daily for 6 weeks to 7 month-old mice that had been permitted to lose bone for 1 month post-ovariectomy. IL-11 at either 50 or 200 microg/kg/day increased platelets and neutrophils in the peripheral blood indicating that a therapeutic dose was achieved, but there was not a significant effect of rhuIL-11 on the plasma concentrations of osteocalcin as compared to vechicle control. In contrast, treatment with 30 micro/kg/day PTH significantly increased plasma osteocalcin. Interestingly, both IL-11 and PTH increased bone mineral density (BMD) of whole femur at the end of the 6-week study. Further studies are required to understand the effects of IL-11 on bone formation and resorption.