JAKPot for treating bone loss

Because JAK blockers have a well-known safety profile, the study results published in Science Translational Medicine indicate they could be used more readily to slow or mitigate the erosion of bone in a variety of diseases.

The JAK enzyme plays a central role in rheumatoid arthritis and other inflammatory conditions, and JAK inhibitors such as tofacitinib have been approved as effective treatments. Although JAK inhibitors are mainly known for their anti-inflammatory effects, some research suggests they may also counteract the pathways that contribute to bone loss that frequently appears in arthritis patients.

Seeking insight, Susanne Adam et al. gave tofacitinib and baricitinib (another JAK inhibitor) to both healthy mice and mice with either inflammatory or noninflammatory bone loss. The drugs increased bone mass in all three rodent models and guarded against further bone erosion in the two disease models. When given to isolated cells, the JAK inhibitors supported the function of bone-building osteoblasts by increasing the activity of the Wnt signaling pathway. Adam et al. then performed CT scans of two patients who received tofacitinib for their rheumatoid arthritis and observed that the treatment repaired a substantial part of the eroded bone in their knuckle joints. Although the findings in patients are preliminary, the researchers say they support further testing of JAK inhibitors as treatments for bone loss in larger groups of patients down the road.