HDAC9 and coronary artery disorder: •SCFAs (acetate, propionate, butyrate): provide energy for intestinal epithelial cells; regulate immunity and metabolism via GPR41/GPR43 activation and HDAC inhibition (103, 104) •Enhances gut barrier function, reduces LPS translocation, alleviates systemic inflammation (105) •High hPDI shows positive effects in preventing coronary heart disease