Currently, some studies have indicated that free fatty acid receptor 4 (FFAR4), a receptor for LCFAs, exacerbates inflammatory bowel disease (IBD) by decreasing the number of Tregs in IBD when the expression of LCFAs is higher [398], which may indirectly demonstrate that LCFAs inhibit the Treg cell effect, as mentioned in other articles [399]. The gene discussed is FFAR4; the disease is inflammatory bowel disease.