Session Type: Abstract Submissions (ACR)
GP88 (progranulin; PGRN), a glycoprotein with a molecular weight of approximately 88000, is suggested to play an important role in the immune response and growth of tumors. Recently, its high affinity for the tumor necrosis factor receptor has been reported and there have been studies on its anti-inflammatory effects in autoimmune diseases. The objectives of the present study were to measure serum PGRN levels in rheumatoid arthritis (RA) patients, to analyze the changes of PGRN levels in RA patients treated with biological products, and to analyze whether PGRN is useful as a biomarker for the diagnosis and therapy evaluation of RA.
Serum PGRN levels were measured using ELISA in 149 healthy subjects (78 men and 71 women) who underwent health checkups (controls) and in 68 RA patients and 24 knee osteoarthritis (OA) patients before the start of treatment, who met the 2010 ACR/EULAR classification criteria and visited the arthritis outpatient clinic. Among RA patients who were non-responsive to methotrexate (MTX), the cryopreserved serum samples of 11 patients who were administered infliximab (IFX) were analyzed to determine the PGRN levels during the course of treatment (at baseline, week 6, week 14, week 22, and week 48).
PGRN levels in the controls were 40.5 ± 14.3 ng/mL in men (mean age, 54.2 years; range, 25–68) and 41.0 ± 10.9 ng/mL in women (mean age, 51.0 years; range, 28–69), and there were no sex and age differences. PGRN levels were significantly higher in RA patients (51.2 ± 12.5 ng/mL) than in OA patients (43.9 ± 5.8 ng/mL) (p<0.01) and controls (p<0.001). Among the RA patients, 10 women and 1 man (mean age, 62.0 years; range, 27.0–78.0) received IFX treatment. MTX was administered orally at 6–8 mg/week, and IFX was administered at 3 mg/kg. Mean PGRN levels at the different time points were as follows: baseline, 45.0 ng/mL; week 6, 46.4 ng/mL; week 14, 50.8 ng/mL; week 22, 48.9 ng/mL; and week 48, 50.4 ng/mL, and there were no significant changes. Because disease activity was high at week 48 and IFX was considered ineffective, 2 cases received a different biological product. Mean PGRN levels in these 2 cases were as follows: baseline, 60.1 ng/mL; week 6, 61.3 ng/mL; week 14, 68.3 ng/mL; week 22, 74.9 ng/mL; and week 48, 79.5 ng/mL, showing an increasing tendency with the treatment course.
Serum PGRN levels were found to be significantly higher in RA patients than in OA patients and controls. Further, no changes in the PGRN levels were found in the group that showed a good response to IFX treatment. However, in cases resistant to IFX, PGRN levels were high when IFX was introduced, followed by an increasing tendency with the treatment course. Owing to the small number of cases in the present study, it is difficult to obtain a clear result. However, the findings showed the possibility of using PGRN levels for the differential diagnosis of RA patients and the therapy evaluation of IFX.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/can-gp88-progranulin-be-used-as-a-biomarker-for-the-diagnosis-and-therapy-evaluation-of-rheumatoid-arthritis/