TNF and periodontitis: One group of researchers found that ageing mice express significantly increased levels of interleukin-1-beta (IL-1β) and tumour necrosis factor-alpha (TNF-α) – two key cytokine mediators of the destructive bone resorption associated with periodontitis.23 Another murine study by Liang et al17,18 revealed the presence of age-related alterations in the expression of 6 out of 15 gingival immune receptors tested.