FN1 and arthritic joint disease: Another component of SF with an influence on bacterial adherence and virulence is fibronectin (Fn).26, 28 Fn is present in healthy SF and elevated in OA SF.26 29 In the context of arthritis citrullinated Fn and Fn’s fragments have been identified as proinflammatory,30, 33 however, its role in interacting with LPS in the joint has not yet been explored.