Skeletal Muscle Dysfunction in Rheumatoid Arthritis (RA)

The investigator plans to enroll 80 participants with RA and 30 non-RA controls between the ages of 35 and 65 between August 2015 and December 2018 (arm-1). The investigator plan to perform a needle muscle biopsy in a subset of participants who agree to undergo this procedure. From the total cohort number of enrolled participants, 36 participants will be identified as having insulin resistance and recruit them to participate in the pioglitazone study (arm-2). Those patients who elect to participate further in the pioglitazone/ placebo study will sign separate consent document during Visit 1.

Since RA is more common in women, it is anticipated that 2/3 of the participants will be women. Children, pregnant or breast-feeding women, adults with impaired consent capacity, or vulnerable populations will not be enrolled.

In the cross-sectional study, after having provided informed consent, participants will undergo a history and physical exam by a rheumatologist to verify diagnosis of RA or that they are a healthy volunteer. All inclusion and exclusion criteria will be verified by the examining physician. During this visit, the participants will complete questionnaires including the Brief Pain Inventory (BPI), Health Assessment Questionnaire (HAQ), Patient Reported Outcomes Measurement Information System (PROMIS) questionnaire and SF-36. Participants will undergo dual energy x-ray absorptiometry (DXA) scanning to assess muscle mass of the upper leg (dominant and non-dominant sides), as well as computed tomography (CT) to assess body composition. Women of child bearing age will undergo urine pregnancy testing. Participants will undergo strength testing and a fatiguing bout of knee extension exercise. Blood will be drawn for glucose, insulin, liver function tests (LFT), lipid profile, rheumatoid factor (RF), anti-citrullinated protein antibodies (ACPA), insulin like growth factor (IGF-1), C-Reactive Protein (CRP), insulin like growth factor binding protein-1 (IGFBP-1) and insulin like growth factor binding protein-3 (IGFBP-3). All participants will be asked to wear an accelerometer for 7 day to measure physical activity. The participants will be scheduled to return to Center for Clinical and Translational Science (CCTS) within 7 days for biopsy of the vastus lateralis muscle.

In the pioglitazone clinical trial study, 36 participants who have insulin resistance will be recruited to receive pioglitazone. After the participants have provided informed consent, women of childbearing potential will be given a urine pregnancy test at visits 1, 3 and 6. The investigator will review participant eligibility and participants will be randomized to receive either pioglitazone 45 mg daily or matching placebo for 15 weeks. Below is the dosing schedule.

Participants will start by taking increasing doses for three weeks as follows: 1 capsule (15mg) per day for 7 days, 1 capsule per day (30 mg) for 7 days, and 1 capsule (45mg), if tolerated. Participants will continue this dose (45 mg) throughout the 10 weeks of treatment. The placebo or non-pioglitazone capsules will look identical to the pioglitazone capsules, but will contain inert substances, and the escalating dose schedule will be the same.