Background/Purpose: We have previously observed an association between exposure to occupational physical workload (PW) and risk of developing rheumatoid arthritis (RA)[1].We posit that PW could impose mechanical stress on the joints leading to neo-epitope formation and immune activation. The major solid component of the articular cartilage is collagen type II (CII). Elevated level of anti-CII antibodies do not predate RA development, but are transiently found in 6-9% early RA patients. These antibodies are associated with acute RA onset and HLA-DRB1*01 and *03, yet predict good long-term prognosis[2]. We hypothesized that exposure to PW especially in the period closely predating RA diagnosis would associate with anti-CII positive RA but not anti-CII negative RA.

Methods: Data involving 1396 incident RA cases and 5935 controls from the Swedish population-based case-control study, Epidemiological Investigation of Rheumatoid Arthritis (EIRA), were analyzed. Information on self-reported exposure to occupational PW was collected through questionnaire. Anti-CII was measured using ELISA. The odds ratio (OR) with 95% confidence interval (CI) of developing anti-CII positive RA or anti-CII negative RA associated with PW exposure was calculated using logistic regression. Adjustment for sex, age, residential area, educational level, alcohol consumption, body mass index, cigarette smoking, silica exposure and occupational class did not substantially change the estimates.

Results: The ORs observed for the association between anti-CII positive RA and different types of PW ranged from 1.0 (95% CI, 0.4-2.4) to 2.3 (95% CI, 1.3-4.0). There was no difference in the ORs for PW exposure at diagnosis or five years earlier (table1). The ORs for the association between anti-CII negative RA and PW ranged from 1.0(95% CI, 0.8-1.3) to 1.8(95% CI, 1.5-2.1). No statistically significant difference was observed between the ORs for anti-CII positive RA and the ORs for anti-CII negative RA (all p-values > 0.2).Stratification for HLA-DRB1*01/*03 or symptom duration did not change the results.

Conclusion: Since physical workload is associated with rheumatoid arthritis irrespective of anti-CII status or the presence of anti-CII associated HLA alleles, and regardless of whether the timing of PW exposure was close to the appearance of anti-CII. We found no evidence suggesting an association between PW and development of anti-CII in RA.

References

1. Zeng P, Klareskog L, Alfredsson L, Bengtsson C. Physical workload is associated with increased risk of rheumatoid arthritis: results from a Swedish population-based case-control study. RMD open 2017;3(1):e000324.

2. Manivel VA, Mullazehi M, Padyukov L, et al. Anticollagen type II antibodies are associated with an acute onset rheumatoid arthritis phenotype and prognosticate lower degree of inflammation during 5 years follow-up. Annals of the rheumatic diseases 2017.

« Back to 2017 ACR/ARHP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/occupational-physical-workload-and-development-of-anti-collagen-type-ii-antibodies-in-rheumatoid-arthritis-patients/