Trefoil factor family protein 3 in cartilage undergoing endochondral ossification in the developing mouse fetus

Trefoil factor 3 (TFF3) is a member of Trefoil factor family of peptides, which are known to have protective effect in various epithelial tissues by promoting restitution of epithelia. They act through various signaling cascades and influence apoptosis. Novel data show that TFF peptides also participate in immune response [1-4]. High expression of TFF3 was found in cartilage of patients with osteoarthritis, and also in mouse models of osteoarthritis and septic arthritis, while no TFF3 expression was observed in healthy human cartilage. TFF3 has also been shown to act as a proapoptotic effector and to promote cartilage degradation in vitro [2]. Throughout endochondral ossification, cartilaginous models of bones are being replaced by bone tissue. During this process, chondrocytes are undergoing proliferation, hypertrophy, and finally death. There is no data about the role of TFF3 in this process. The aim of this study was to investigate if TFF3 is expressed in cartilage undergoing endochondral ossification. Mouse fetuses, day 15, 16, 17 were isolated, fixed, paraffin embedded, cut (5µm), and processed for immunohistochemical staining. Primary monoclonal rabbit anti-TFF3 antibody was used, and PBS as a negative control. TFF3 was found in chondrocytes of cartilage undergoing endochondral ossification, in zone of proliferation, zone of hypertrophy and calcification and zone of cartilage degeneration in all monitoring time points (Fig.1). No signal was observed in the zone of resting cartilage. Expression pattern of TFF3 during endochondral ossification shows analogy to that in cartilage affected by inflammation in osteoarthritis and septic arthritis. This preliminary data show that similar mechanisms might be involved in the physiological process of endochondral ossification, and that TFF3 plays an important role in it. 1. Regalo G, Wright NA, Machado JC. Trefoil factors: from ulceration to neoplasia. Cell. Mol. Life Sci. 62 (2005) p.2910-15. 2. Rosler S et al. Trefoil Factor 3 is induced during degenerative and inflammatory joint disease, activates matrix metalloproteinases, and enhances apoptosis of articular cartilage chondrocytes. Arthritis Rheum. 62 (2010), p.815-25. 3. Baus-Loncar M, Giraud AS. Multiple regulatory pathways for trefoil factor (TFF) genes. Cell. Mol. Life Sci. 62 (2005) p.2921-31. 4. Baus-Loncar M et al. Trefoil factor family 2 deficiency and immune response. Cell. Mol. Life Sci. 62 (2005) p.2947- 55.