CXCL9 and periodontitis: Moreover, chemokines such as CXCL8 [42], CXCL10 [43], CXCL12 [44], and CCL5 [45] accumulate in the crevicular fluid of periodontitis patients and their source might be attributed to fibroblasts at least for CXCL2, CXCL3, CXCL8, CXCL9, CXCL10, CXCL12, and CXCL16 [20].