DKK1 and viral infectious disease: We carefully designed this experiment with a whole set of control groups; there were eight groups in total to be conducted for the DKK1 expression manipulations in which there were parallel four groups for chow or HFD condition, including control (no virus infection, first control), AAV-GFP-NC (secondary control), AAV-OE-DKK1 (overexpressing DKK1), and AAV-sh-DKK1 (knock-down DKK1), respectively.