Arthritis & Rheumatism, Volume 63,
November 2011 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Chicago, Illinois November 4-9, 2011.


Pro-Inflammatory Cytokine Measurement in Whole Blood Cultures Stimulated with Lipopolysaccharide Predicts Treatment Outcomes of Patients with Rheumatoid Arthritis Treated with Biologics.

Kayakabe1,  Ken, Kuroiwa2,  Takashi, Sakurai1,  Noriyuki, Ikeuchi1,  Hidekazu, Anastasie1,  K.T., Sakairi1,  Toru, Maeshima1,  Akito

Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
Jichi Medical University, Saitama Medical Center, Saitama, Japan

Background/Purpose:

Although biological therapies targeting tumor necrosis factor (TNF)-a or interleukin (IL)-6 are highly effective for rheumatoid arthritis (RA), they are expensive and occasionally associated with severe side effects. Therefore, it is important to identify patients who respond or do not respond to the biologics. Possibility exists that such response is associated with each patient's capacity of pro-inflammatory cytokine production. Whole blood culture with lipopolysaccharide (LPS) stimulation is a valid low-cost method to measure cytokine synthesis in monocytes. To find predictors of response to biologics, we examined pro-inflammatory cytokine production in whole blood culture.

Methods:

Whole blood was obtained from biologics-naïve patients with RA (n=41) before starting biologics (infliximab 13, etanercept 26, and adalimumab 2). At 6 months after initiation of biologics, whole blood was again drawn from 14 out of 41patients. Blood from 12 healthy volunteers were used as controls. We measured the concentration of TNF-a, IL-1b and IL-6 in supernatants of LPS-stimulated (at 1ng/ml, for 24 hrs) whole blood culture. Disease activity score (DAS28) was evaluated at baseline and 6 months after the therapy. Response to the therapy was defined by EULAR response criteria.

Results:

The mean age of the patients was 55.9 yrs and 87.8% of them were female. The median of disease duration was 44.0 months. The mean DAS28 at baseline was 4.48. Rheumatoid factor and anti-citrullinated peptide antibodies were positive in 70.0% and 84.2%, respectively. The patients treated with methotrexate were 78.0% (mean 7.0 mg/week). Among patients examined, 32 were responders (good 14/moderate 18), and 9 were non-responders. All cytokines measured were significantly lower in RA patients than in healthy controls (the median and [interquartile range] of TNF-a: 30.4 [9.6, 149] vs. 256 [172, 406] pg/ml p=0.002, IL-1b: 6.9 [2.9, 75] vs. 256 [229, 371] pg/ml p<0.001, IL-6: 358 [65.3, 1975] vs. 1933 [1320, 2984] pg/ml p=0.004). In RA patients, IL-1b production before therapy was significantly lower in non-responders than in responders (3.48 [1.51, 9.41] vs. 10.0 [5.21, 93.1] pg/ml p=0.048). TNF-a and IL-6 were also lower in non-responders than in responders, but statistical significance was not observed (TNF-a: 23.0 [2.23, 66.5] vs. 31.5 [11.0, 224] pg/ml p=0.393, IL-6: 185 [45.3, 1257] vs. 366 [76.1, 2333] pg/ml, p=0.546). The area under the curve (AUC) from a receiver operating characteristic (ROC) curve analysis for the prediction of response using IL-1b was 0.717 (95% CI; 0.520 – 0.914). The sensitivity and specificity of IL-1b (cut-off value of 4.84pg/ml) were 78.1% and 77.8%, respectively. All cytokines were significantly higher after 6 month later of biologic therapy as compared with the respective baselines (TNF-a: 142 [38.0, 431] vs. 16.8 [7.45, 24.8] pg/ml p=0.004, IL-1b: 30.9 [7.11, 84.5] vs. 5.86 [1.02, 10.6] pg/ml p=0.001, IL-6: 1061 [385, 2286] vs. 122 [50.6, 275] pg/ml p=0.001).

Conclusion:

This preliminary study suggests that IL-1b production in whole blood culture predicts the response to the biologic therapy. Cytokine production capacity is up-regulated by the biologic therapy. Larger studies to prove this concept are warranted.

To cite this abstract, please use the following information:
Kayakabe, Ken, Kuroiwa, Takashi, Sakurai, Noriyuki, Ikeuchi, Hidekazu, Anastasie, K.T., Sakairi, Toru, et al; Pro-Inflammatory Cytokine Measurement in Whole Blood Cultures Stimulated with Lipopolysaccharide Predicts Treatment Outcomes of Patients with Rheumatoid Arthritis Treated with Biologics. [abstract]. Arthritis Rheum 2011;63 Suppl 10 :1828
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