The possible role of the transcription factor NF-kB on evolution of rotator cuff tear and on mechanisms of cuff tendon healing.

Abstract: HYPOTHESIS: We verified if the nuclear factor-kappa beta (NF-kB) was present on the margins of rotator cuff tears (RCT). Since NF-kB regulates apoptosis and stimulates neoangiogenesis, we hypothesized that NF-kB has a role on evolution of RCT and on possible mechanisms of RCT healing. MATERIALS AND METHODS: Samples from tear margins, subacromial bursa and healthy subscapular tendons were excised during arthroscopic treatment of patients with postero-superior-RCT. Sections were cut and stained with HE for morphologic evaluation and used for immunoistochemical analysis with NF-kB-p65 antibody. RESULTS: The presence of the NF-kB in the RCT margins and subacromial bursa increases with the increasing of the tear size; it is also present in the subscapularis tendon of patients with large and massive RCT. Analogously, we have observed that neoangiogenesis grows with the increasing of the RCT size and it is always present in the subscapularis tendon independently from RCT size. Statistical analysis indicates that NF-kB and neoangiogenesis are correlated in spite of the dimension of the RCT. DISCUSSION: We hypothesized possible causes for NF-kB activation in RCT; however we believe that activation is mainly due to tissue hypoxia. Furthermore, our data suggest that the same factors that regulate NF-kB activation also act as neoangiogenesis inductors. CONCLUSIONS: Two possible hypotheses could explain the increase of neoangiogenesis in the margins of the rotator cuff tears: 1) activated p65 directly stimulates neoangiogenesis; 2) the same factors responsible for p65 activation also act as neoangiogenesis inductors.