Background/Purpose: Osteoarthritis (OA) affects 33.6% of population ≥65. Knee OA (KOA) is the most prevalent OA and it is one of five leading causes of disability of non-institutionalized adults. Aging and excessive body mass are two strongest risk factor for KOA. Biomechanical theory suggests that increase in axial load would promote degeneration in cartilage. However, it is undermined by the fact that even OA of non weight bearing joint such as carpometacarpal joint of the thumb is associated with obesity. Both obesity and aging, risk factors for OA are associated with low grade inflammation. Microbial translocation (MT) is defined as the passage of both viable and nonviable microbial products such as LPS across an anatomically intact intestinal barrier. A higher burden of microbial translocation with aging is reported both in animal and human studies. Obesity is also known to be associated with increased MT. Recently, MT is thought to be the source of low grade inflammation in obesity and aging, and it is possible that MT activates innate immunity which in turn causes the low grade inflammation seen in OA.

Methods:

The Intensive Diet and Exercise for Arthritis (IDEA) study is a prospective, randomized controlled trial of 454 overweight and obese older adults with tibiofemoral osteoarthritis. Two subgroups were selected from IDEA study (n=22 each): a group that showed radiographic progression (≥0.7mm decrease in joint space width, JSW) and age, gender, and BMI matched group who did not progress (≤0.35 mm decrease in JSW). Stored baseline blood samples were analyzed for markers of MT: lipoprotein binding protein-1 (LBP-1) and soluble cluster of differentiation 14 (sCD14). Multivariate analyses were performed to examine the association with baseline MT and KOA progression as well as the OA outcomes using Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC).

Results: The mean age was 66 (SD 5.3), 68% female, and mean BMI was 30.5 (SD 4.6). There was no association between baseline MT translocation and OA progression. However in multivariate analysis baseline Scd14 is positively associated functional limitation for 18 months WOMAC function measure (coefficient 0.37, p=0.03) after controlling for age, weight, randomization group.

Conclusion:: In this secondary analysis of IDEA study, a microbial translocation marker at baseline is predictive of 18 months functional outcome. Future study to explore the mechanisms of this association is warranted.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-association-of-microbial-translocation-and-womac-function-in-patients-with-knee-osteoarthritis/