SPP1 and alcoholic fatty liver disease: Extensive data showed that OPN is abundantly expressed in the liver, brain, kidney, and placenta of humans and mice, which has been proven with participation in several disease conditions, including inflammation, liver fibrosis, and non-alcoholic fatty liver disease.161 Epididymal white adipose tissue-resident macrophages constitute a cellular source of OPN, which undergoes endocrine transport to the osseous niche.162 This adipokine mediates bone ECM remodeling through paracrine activation of osteoclast-mediated resorptive activity.