Scand J Rheumatol 2014;43:75–84
75
LETTERS
HLA-DRB1 associations with rheumatoid arthritis-related pulmonary fibrosis H Ennis1, A Gupta2, J Dawson3, M Lunt1, W Thomson1, A Herrick1 1
Centre for Musculoskeletal Research, The University of Manchester, Manchester Academic Health Science Centre, Rheumatology, Nottingham University Hospitals NHS Trust, and 3Rheumatology, St Helens and Knowsley Teaching Hospitals NHS Trust, UK 2
The aetiology of rheumatoid arthritis (RA)-related pulmonary fibrosis (PF), one of the major extraarticular manifestations of RA (1), remains unknown and is likely to be multifactorial (2). However, to date only a few studies have examined its genetic basis (3). The association between RA and a number of human leucocyte antigen (HLA)-DRB1 alleles that share a common sequence (4), known as the shared epitope (SE), is well known. Our objective was to perform a pilot study to determine whether there is a difference between HLA-DRB1 alleles associated with susceptibility to RA-related PF compared with RA alone. Fifty-two Caucasian patients (33 males, median age at onset of RA 54 years, median disease duration 11 years) with RA-related PF were recruited from hospitals across North West England. The study was approved by the North West Research Ethics Committee and all patients signed an informed consent form. PF was confirmed by high-resolution computed tomography in 48 (92%) cases: in the other four, diagnosis was on the basis of bilateral basal shadowing on chest X-ray with a restrictive defect on pulmonary function testing. DNA
samples from 537 healthy Caucasian controls and 3397 Caucasian RA patients recruited by the UK Rheumatoid Arthritis Genetics (UKRAG) Consortium were available for comparison. HLA-DRB1 genotyping was performed using Dynal RELI sequence-specific oligonucleotide (SSO) HLA-DRB1 kits. HLA-DRB1 allele frequencies in patients with RA-related PF were compared with those in healthy controls, and with RA patients from the UKRAG Consortium (Table 1). A two-stage statistical analysis was used to account for the multi-allelic nature of HLA-DRB1 and the small sample size. An overall Pearson χ 2 test of broad-type HLA-DRB1 allele frequencies was performed, and allele frequencies were compared with a reference allele using multinomial logistic regression. Allele and phenotype frequencies for the broad-type HLA-DRB1 alleles in RA-related PF cases, RA cases, and healthy controls are shown in Table 1. HLA-DRB1 SE analysis: The frequency of SE carriage was 70, 75, and 46% in RA-related PF, RA, and healthy controls, respectively. Carriage of SE was significantly higher in RA-related PF cases compared with healthy controls [odds ratio (OR) 2.80, 95%
Table 1. Allele and phenotype frequencies for the broad-type HLA-DRB1 alleles in PF cases, RA cases, and healthy controls. Allele frequencies (%)
Phenotype frequencies (%)
HLA-DRB1*
PF cases (n ¼ 52)
RA cases (n ¼ 3,397)
Controls (n ¼ 537)
PF cases (n ¼ 52)
RA cases (n ¼ 3397)
Controls (n ¼ 537)
01 02 03 04 07 08 09 10 11 12 13 14 15/16 17
17 (16.35) 0 (0.00) 13 (12.50) 28 (26.92) 17 (16.35) 1 (0.96) 4 (3.85) 2 (1.92) 2 (1.92) 3 (2.88) 5 (4.81) 0 (0.00) 12 (11.54) 0 (0.00)
861 (12.67) 17 (0.25) 924 (13.60) 2,675 (39.37) 602 (8.86) 81 (1.19) 96 (1.41) 74 (1.09) 241 (3.55) 74 (1.09) 328 (4.83) 90 (1.32) 730 (10.74) 1 (0.01)
133 (12.38) 0 (0.00) 163 (15.18) 214 (19.93) 141 (13.13) 37 (3.45) 12 (1.12) 8 (0.74) 62 (5.77) 12 (1.12) 103 (9.59) 31 (2.89) 158 (14.71) 0 (0.00)
15 (28.85) 0 (0.00) 12 (23.08) 24 (46.15) 17 (32.69) 1 (1.92) 4 (7.69) 2 (3.85) 2 (3.85) 3 (5.77) 5 (9.62) 0 (0.00) 12 (23.08) 0 (0.00)
805 (23.70) 17 (0.50) 837 (24.64) 2,103 (61.91) 572 (16.84) 80 (2.36) 96 (2.83) 73 (2.15) 231 (6.80) 74 (2.18) 314 (9.24) 88 (2.59) 686 (20.19) 1 (0.03)
127 (23.65) 0 (0.00) 152 (28.31) 195 (36.31) 129 (24.02) 37 (6.89) 12 (2.23) 8 (1.49) 61 (11.36) 11 (2.05) 96 (17.88) 30 (5.59) 145 (27.00) 0 (0.00)
© 2014 Informa Healthcare on license from Scandinavian Rheumatology Research Foundation DOI: 10.3109/03009742.2013.841284
www.scandjrheumatol.dk
76
Letters
confidence interval (CI) 1.45–5.63, p ¼ 0.001]. Although RA cases appeared to carry two copies of the SE more often than RA-related PF (26% vs. 16%), overall there was no significant difference in carriage of SE between these two groups (OR 0.81, 95% CI 0.43–1.60, p ¼ 0.517). Cases vs. healthy controls: The overall χ 2 test indicated significant differences in HLA-DRB1 broad-type allele frequencies (χ 2 ¼ 24.12, p ¼ 0.012). Using HLADRB1*03 as a reference (most common non-SE positive allele), DRB1*04, *01, and *07 were more common among the PF cases than the controls, whereas HLADRB1*08, *11, and *13 were less common among the PF cases than the controls. Cases vs. RA alone: The overall χ 2 test did not reach statistical significance (χ 2 ¼ 21.94, p ¼ 0.056). Using HLA-DRB1*03 as a reference, HLA-DRB1*07 and *01 were associated with susceptibility to PF whereas HLADRB1*08, *04, and *11 were less common among PF cases. The comparison was repeated using HLADRB1*04 as a reference and HLA-DRB1*07 again indicated susceptibility to RA-related PF (OR 2.70, 95% CI 1.47–4.96, p ¼ 0.001). The heterogeneity of both clinical phenotypes (RA without and with PF) is an important limitation for genetic studies, and is a particular challenge when studying RA-related PF, which can be difficult to diagnose. However, this pilot study detected a differ-
ence between HLA-DRB1 alleles in susceptibility to RA-related PF compared to RA alone, with evidence that the DRB1*07 allele increases the risk of PF in a manner unrelated to RA susceptibility. Acknowledgements We are grateful to all the clinicians who recruited patients into the study, and to Laura Gibbons for HLA typing.
References 1. Turesson C, Jacobsson LTH. Epidemiology of extra-articular manifestations in rheumatoid arthritis. Scand J Rheumatol 2004;33:65–72. 2. Ascherman DP. Interstitial lung disease in rheumatoid arthritis. Curr Rheumatol Rep 2010;12:363–9. 3. Hillarby MC, McMahon MJ, Grennan DM, Cooper RG, Clarkson RW, Davies EJ, et al. HLA associations in subjects with rheumatoid arthritis and bronchiectasis but not with other pulmonary complications of rheumatoid disease. Br J Rheumatol 1993;32:794–7. 4. Thomson W, Barton A, Ke X, Eyre S, Hinks A, Bowes J, et al. Rheumatoid arthritis association at 6q23. Nat Genet 2007;39:1431–3.
Ariane Herrick, Centre for Musculoskeletal Research, University of Manchester, Stopford Building, Oxford Road, Manchester M13 9PT, UK. E-mail: [email protected] Accepted 1 September 2013
Calprotectin (S100A8/A9), S100A12, and EDTA-resistant S100A12 complexes (ERAC) in primary Sjögren’s syndrome HH Nordal1,2, JG Brun1,2, A-K Halse1,2, TM Madland2, MK Fagerhol3, R Jonsson1,2 1 3
Department of Clinical Science, University of Bergen, 2Department of Rheumatology, Haukeland University Hospital, Bergen, and Prof. Fagerhol’s Research Laboratory, Oslo, Norway
The proteins calprotectin (a heterocomplex of S100A8/A9) and S100A12 are expressed mainly by phagocytes, have proinflammatory properties, and have been suggested as
markers of inflammation in arthritis and autoimmune diseases (1). ERAC are large ethylenediaminetetraacetic acid (EDTA)-resistant protein complexes containing S100A12
Table 1. Concentrations of S100 proteins (median values) in serum of patients compared with reference intervals and controls.
Calprotectin S100A12 ERAC*
Patients (n ¼ 141)
Reference interval
2611 (IQR 1723) 1407 (IQR 1865) 0 (IQR 0) Four positive (> 4 ng/mL)
80–800 49–1340
IQR, Interquartile range. *For ERAC, sera samples were available from 140 patients. Values given in ng/mL.
www.scandjrheumatol.dk
Controls (n ¼ 94)
0 (IQR 0) None positive (> 4 ng/mL)
Copyright of Scandinavian Journal of Rheumatology is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
75
LETTERS
HLA-DRB1 associations with rheumatoid arthritis-related pulmonary fibrosis H Ennis1, A Gupta2, J Dawson3, M Lunt1, W Thomson1, A Herrick1 1
Centre for Musculoskeletal Research, The University of Manchester, Manchester Academic Health Science Centre, Rheumatology, Nottingham University Hospitals NHS Trust, and 3Rheumatology, St Helens and Knowsley Teaching Hospitals NHS Trust, UK 2
The aetiology of rheumatoid arthritis (RA)-related pulmonary fibrosis (PF), one of the major extraarticular manifestations of RA (1), remains unknown and is likely to be multifactorial (2). However, to date only a few studies have examined its genetic basis (3). The association between RA and a number of human leucocyte antigen (HLA)-DRB1 alleles that share a common sequence (4), known as the shared epitope (SE), is well known. Our objective was to perform a pilot study to determine whether there is a difference between HLA-DRB1 alleles associated with susceptibility to RA-related PF compared with RA alone. Fifty-two Caucasian patients (33 males, median age at onset of RA 54 years, median disease duration 11 years) with RA-related PF were recruited from hospitals across North West England. The study was approved by the North West Research Ethics Committee and all patients signed an informed consent form. PF was confirmed by high-resolution computed tomography in 48 (92%) cases: in the other four, diagnosis was on the basis of bilateral basal shadowing on chest X-ray with a restrictive defect on pulmonary function testing. DNA
samples from 537 healthy Caucasian controls and 3397 Caucasian RA patients recruited by the UK Rheumatoid Arthritis Genetics (UKRAG) Consortium were available for comparison. HLA-DRB1 genotyping was performed using Dynal RELI sequence-specific oligonucleotide (SSO) HLA-DRB1 kits. HLA-DRB1 allele frequencies in patients with RA-related PF were compared with those in healthy controls, and with RA patients from the UKRAG Consortium (Table 1). A two-stage statistical analysis was used to account for the multi-allelic nature of HLA-DRB1 and the small sample size. An overall Pearson χ 2 test of broad-type HLA-DRB1 allele frequencies was performed, and allele frequencies were compared with a reference allele using multinomial logistic regression. Allele and phenotype frequencies for the broad-type HLA-DRB1 alleles in RA-related PF cases, RA cases, and healthy controls are shown in Table 1. HLA-DRB1 SE analysis: The frequency of SE carriage was 70, 75, and 46% in RA-related PF, RA, and healthy controls, respectively. Carriage of SE was significantly higher in RA-related PF cases compared with healthy controls [odds ratio (OR) 2.80, 95%
Table 1. Allele and phenotype frequencies for the broad-type HLA-DRB1 alleles in PF cases, RA cases, and healthy controls. Allele frequencies (%)
Phenotype frequencies (%)
HLA-DRB1*
PF cases (n ¼ 52)
RA cases (n ¼ 3,397)
Controls (n ¼ 537)
PF cases (n ¼ 52)
RA cases (n ¼ 3397)
Controls (n ¼ 537)
01 02 03 04 07 08 09 10 11 12 13 14 15/16 17
17 (16.35) 0 (0.00) 13 (12.50) 28 (26.92) 17 (16.35) 1 (0.96) 4 (3.85) 2 (1.92) 2 (1.92) 3 (2.88) 5 (4.81) 0 (0.00) 12 (11.54) 0 (0.00)
861 (12.67) 17 (0.25) 924 (13.60) 2,675 (39.37) 602 (8.86) 81 (1.19) 96 (1.41) 74 (1.09) 241 (3.55) 74 (1.09) 328 (4.83) 90 (1.32) 730 (10.74) 1 (0.01)
133 (12.38) 0 (0.00) 163 (15.18) 214 (19.93) 141 (13.13) 37 (3.45) 12 (1.12) 8 (0.74) 62 (5.77) 12 (1.12) 103 (9.59) 31 (2.89) 158 (14.71) 0 (0.00)
15 (28.85) 0 (0.00) 12 (23.08) 24 (46.15) 17 (32.69) 1 (1.92) 4 (7.69) 2 (3.85) 2 (3.85) 3 (5.77) 5 (9.62) 0 (0.00) 12 (23.08) 0 (0.00)
805 (23.70) 17 (0.50) 837 (24.64) 2,103 (61.91) 572 (16.84) 80 (2.36) 96 (2.83) 73 (2.15) 231 (6.80) 74 (2.18) 314 (9.24) 88 (2.59) 686 (20.19) 1 (0.03)
127 (23.65) 0 (0.00) 152 (28.31) 195 (36.31) 129 (24.02) 37 (6.89) 12 (2.23) 8 (1.49) 61 (11.36) 11 (2.05) 96 (17.88) 30 (5.59) 145 (27.00) 0 (0.00)
© 2014 Informa Healthcare on license from Scandinavian Rheumatology Research Foundation DOI: 10.3109/03009742.2013.841284
www.scandjrheumatol.dk
76
Letters
confidence interval (CI) 1.45–5.63, p ¼ 0.001]. Although RA cases appeared to carry two copies of the SE more often than RA-related PF (26% vs. 16%), overall there was no significant difference in carriage of SE between these two groups (OR 0.81, 95% CI 0.43–1.60, p ¼ 0.517). Cases vs. healthy controls: The overall χ 2 test indicated significant differences in HLA-DRB1 broad-type allele frequencies (χ 2 ¼ 24.12, p ¼ 0.012). Using HLADRB1*03 as a reference (most common non-SE positive allele), DRB1*04, *01, and *07 were more common among the PF cases than the controls, whereas HLADRB1*08, *11, and *13 were less common among the PF cases than the controls. Cases vs. RA alone: The overall χ 2 test did not reach statistical significance (χ 2 ¼ 21.94, p ¼ 0.056). Using HLA-DRB1*03 as a reference, HLA-DRB1*07 and *01 were associated with susceptibility to PF whereas HLADRB1*08, *04, and *11 were less common among PF cases. The comparison was repeated using HLADRB1*04 as a reference and HLA-DRB1*07 again indicated susceptibility to RA-related PF (OR 2.70, 95% CI 1.47–4.96, p ¼ 0.001). The heterogeneity of both clinical phenotypes (RA without and with PF) is an important limitation for genetic studies, and is a particular challenge when studying RA-related PF, which can be difficult to diagnose. However, this pilot study detected a differ-
ence between HLA-DRB1 alleles in susceptibility to RA-related PF compared to RA alone, with evidence that the DRB1*07 allele increases the risk of PF in a manner unrelated to RA susceptibility. Acknowledgements We are grateful to all the clinicians who recruited patients into the study, and to Laura Gibbons for HLA typing.
References 1. Turesson C, Jacobsson LTH. Epidemiology of extra-articular manifestations in rheumatoid arthritis. Scand J Rheumatol 2004;33:65–72. 2. Ascherman DP. Interstitial lung disease in rheumatoid arthritis. Curr Rheumatol Rep 2010;12:363–9. 3. Hillarby MC, McMahon MJ, Grennan DM, Cooper RG, Clarkson RW, Davies EJ, et al. HLA associations in subjects with rheumatoid arthritis and bronchiectasis but not with other pulmonary complications of rheumatoid disease. Br J Rheumatol 1993;32:794–7. 4. Thomson W, Barton A, Ke X, Eyre S, Hinks A, Bowes J, et al. Rheumatoid arthritis association at 6q23. Nat Genet 2007;39:1431–3.
Ariane Herrick, Centre for Musculoskeletal Research, University of Manchester, Stopford Building, Oxford Road, Manchester M13 9PT, UK. E-mail: [email protected] Accepted 1 September 2013
Calprotectin (S100A8/A9), S100A12, and EDTA-resistant S100A12 complexes (ERAC) in primary Sjögren’s syndrome HH Nordal1,2, JG Brun1,2, A-K Halse1,2, TM Madland2, MK Fagerhol3, R Jonsson1,2 1 3
Department of Clinical Science, University of Bergen, 2Department of Rheumatology, Haukeland University Hospital, Bergen, and Prof. Fagerhol’s Research Laboratory, Oslo, Norway
The proteins calprotectin (a heterocomplex of S100A8/A9) and S100A12 are expressed mainly by phagocytes, have proinflammatory properties, and have been suggested as
markers of inflammation in arthritis and autoimmune diseases (1). ERAC are large ethylenediaminetetraacetic acid (EDTA)-resistant protein complexes containing S100A12
Table 1. Concentrations of S100 proteins (median values) in serum of patients compared with reference intervals and controls.
Calprotectin S100A12 ERAC*
Patients (n ¼ 141)
Reference interval
2611 (IQR 1723) 1407 (IQR 1865) 0 (IQR 0) Four positive (> 4 ng/mL)
80–800 49–1340
IQR, Interquartile range. *For ERAC, sera samples were available from 140 patients. Values given in ng/mL.
www.scandjrheumatol.dk
Controls (n ¼ 94)
0 (IQR 0) None positive (> 4 ng/mL)
Copyright of Scandinavian Journal of Rheumatology is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
