TNF and tuberculosis: Nicotine in tobacco attenuates innate immune responses against TB by decreasing expression of toll-like receptors and production of cytokines (interleukin [IL]—6 and 8 and tumor necrotic factor alpha [TNFα]) and chemokines by lung epithelial cells, macrophages and type 2 pneumocytes.[12,13] Together, these mechanisms could explain why smoking increases the risk of TB infection and disease.