Preventing Bone Loss in Rheumatoid Arthritis

Researcher seeks tool to predict progressive erosion

Dr. Julie Baker-LePain

Rita Savio's rheumatoid arthritis (RA) appears to be in remission. Her blood work is normal, there is no evidence of inflammation in her joints and overall she feels well.

But there is an unexpected problem. Her yearly x-rays indicate progressive erosion of the bones in her knuckles. Rita is one of about 20 percent of RA patients who have ongoing bone erosion even though accompanying symptoms have been controlled by medication, either methotrexate or anti-TNF inhibitors, both standards of care.

Julie Baker-LePain, MD, PhD, a recently graduated UCSF Rheumatology Fellow and current Clinical Instructor, hopes to find a marker in the blood that predicts which RA patients will have ongoing bone erosion. Now doctors rely on yearly x-rays to determine that such a problem exists. The development of a test that would allow doctors to detect ongoing erosion without having to wait for x-rays, however, could lead to earlier adjustment of medications to help prevent bone loss. Dr. Baker-LePain's research is supported by the Rosalind Russell Medical Research Center for Arthritis.

In healthy people, the ongoing degradation of bone is precisely balanced by bone formation. The net result is that bones are maintained over time. In RA patients, however, the balance is thrown off and bone loss wins out.

Dr. Baker-LePain is working with blood samples donated by UCSF RA patient volunteers. Specifically, she is counting a kind of precursor cell that has not yet transformed into a mature cell that degrades bone.

A previous pilot study suggests that the number of these precursor cells correlates with joint erosion in RA patients and patients with psoriatic arthritis. Dr. Baker-LePain's first step is to confirm this hypothesis in RA patients on a larger scale. If confirmed, further study involving patients' x-rays "will tell us whether patients who have a high number of these precursor cells are more prone to develop erosions than patients who have a low number," says Dr. Baker-LePain.

This could lead to development of a simple predictive blood test, which some day would help patients like Rita Savio.

Dr. Baker-LePain hopes to find a marker in the blood that predicts which RA patients will have ongoing bone erosion.

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