TNF and intervertebral disk degenerative disorder: TNF-α and IL-1β are key inflammatory mediators of IDD, positively correlating with the severity and promoting ECMs catabolism by up-regulating proteolytic enzymes, whilst inhibiting the expression and synthesis of proteoglycan (Le Maitre et al., 2005; Doita et al., 2001; Jimbo et al., 2005).