Abstract
BackgroundLabral tear can be the initiating factor in the onset of hip osteoarthritis (HOA). However, the physiopathology of labral tear is not fully understood. Our aim was to compare synovial tissue inflammatory cytokine levels between patients with labral tear and late-stage HOA.MethodsSynovial tissue from sites showing the greatest inflammation was harvested from 106 hips from 100 subjects during hip surgery. RNA was extracted, and levels of TNFA, IL1B, IL6 and COX2 mRNA were compared among all patients using real-time PCR. Additionally, we examined whether femoroacetabular impingement (FAI) was associated with elevated levels of inflammatory cytokines in patients with labral tear. To analyze the effects of TNF-α on inflammatory mediators in hip synovial tissue, synovial fibroblasts were extracted from hip synovial tissue of patients with labral tear and late-stage HOA (n = 5 each). Mononuclear cells were extracted from synovial tissue, cultured for 7 days, and stimulated with control or 10 ng/mL human recombinant TNF-α for 1 day. mRNA was extracted from stimulated cells and IL1B, IL6, and COX2 levels were determined using real-time PCR.ResultsTNFA, IL1B, and COX2 expression in synovial tissue were significantly higher in patients with labral tear than late-stage HOA (TNFA, p < 0.001; IL1B, p < 0.001; COX2, p = 0.001). There were no differences in expression between patients with labral tear with and without FAI (TNFA, p = 0.546; IL1B, p = 0.559; IL6, p = 0.599; COX2, p = 0.124). Compared to vehicle control, TNF-α stimulation significantly elevated IL1B, IL6, and COX2 expression in synovial fibroblasts collected from patients with labral tear and late-stage HOA (IL1B, p = 0.043 and p = 0.043; IL6, p = 0.043 and 0.043; COX2, p = 0.043 and p = 0.080, respectively).ConclusionsTNFA, IL1B, and COX2 expression were elevated in the synovial tissue of patients with labral tear. Further investigations are needed to reveal the relationship between inflammatory cytokine levels and various aspects of labral tear pathology, including pain and the onset and progression of OA.
Highlights
Labral tear can be the initiating factor in the onset of hip osteoarthritis (HOA)
We previously reported that Tumor necrosis factor-α (TNF-α) levels were significantly elevated in patients who received arthroscopic surgery and showed HOA progression after surgery compared to those who did not show HOA progression [13]
visual analog scale (VAS) score on walking was significantly higher in patients with late-stage HOA than labral tear (LT) (P = 0.024)
Summary
Labral tear can be the initiating factor in the onset of hip osteoarthritis (HOA). The physiopathology of labral tear is not fully understood. Our aim was to compare synovial tissue inflammatory cytokine levels between patients with labral tear and late-stage HOA. A labral tear (LT) can be preceded by femoroacetabular impingement (FAI), hip dysplasia, or hip osteoarthritis (HOA) [4]. Studies suggest that synovial inflammation is a key factor in the pain induced by LT, and in the initiation and progression of osteoarthritis (OA) induced by it [6,7,8,9]. A recent study reported that labral degeneration is positively correlated with synovial inflammation in patients with FAI [10]. Synovial inflammation in LT has not been fully characterized
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