TGFB1 and atrial fibrillation: The infiltration of inflammatory cells into the atrial tissue, with particular emphasis on the infiltration of CD68 positive macrophages, as well as increased production of IL-6 and tissue growth factor β (TGFβ) by macrophages in patients with AF are some of the described mechanisms contributing to an increased expression of inflammatory cytokines such as IL-6, interleukin 8, interleukin 10 and TNF.