Anti-peptidylarginine deiminase-4 antibodies at mucosal sites can activate peptidylarginine deiminase-4 enzyme activity in rheumatoid arthritis

Table 1 Subject characteristics

	RA (N = 37)	At-risk (N = 46)	Controls (N = 25)	p value
Age, median (IQR)	56 (42–61)	52 (46–63)	36 (28–54)	<0.01
Female	27 (73)	29 (63)	21 (84)	0.18
Non-Hispanic white	22 (60)	32 (70)	18 (72)	0.51
Ever-smoker	17 (46)	18 (39)	8 (32)	0.54
Current smoker	7 (19)	5 (11)	0 (0)	0.05
≥1 shared epitope allele¹	23 (72)¹	20 (44)	13 (52)	0.04
Chronic lung disease²	9 (24)	8 (17)	4 (16)	0.86
RA duration >2 years	9 (24)	–	–	–
Serum anti-CCP+	37 (100)	26 (57)	0 (0)	<0.01
Serum anti-PAD4+	6 (16)	1 (2)	0 (0)	0.02
Serum anti-PAD3/4+	2 (5)	1 (2)	0 (0)	0.60
Sputum anti-CCP+	18 (49)	11 (24)	0 (0)	<0.01
Sputum anti-PAD4+	3 (8)	1 (2)	0 (0)	0.28
Sputum anti-PAD3/4+	1 (3)	1 (2)	0 (0)	1.0
Salivary anti-CCP+³	11 (30)	4 (14)	0 (0)	<0.01
Salivary anti-PAD4+³	3 (9)	0 (0)	0 (0)	0.11
Salivary anti-PAD3/4+	0 (0)	0 (0)	0 (0)	1.0

Values are listed as N (%) unless otherwise noted
¹Only 32 of 37 RA subjects had DNA available for SE testing
²Chronic lung disease was defined as a self-report of a health care provider diagnosis of chronic asthma, emphysema, bronchitis, bronchiectasis, interstitial lung disease, or other chronic lung diseases
³Only 33 RA, 31 at-risk, and 21 controls had saliva available for testing. After anti-PAD4 testing, only 28 RA, 28 at-risk, and 19 controls had saliva available for anti-CCP testing

ISSN: 1478-6362