TFF1 was detected in all samples except for one case of healthy SF and was not significantly changed between healthy (50.9 pg/mg, ranging from 0.8 to 258.1 pg/mg) and disease-affected conditions (OA: 31.2 pg/mg, ranging from 9.5 to 117.3 pg/mg; and RA: 33.0 pg/mg, ranging from 18.8 to 67.7 pg/mg) (Figure 3B and Table 2). Here, TFF1 is linked to rheumatoid arthritis.