Page 94 - Recognizing axial spondyloarthritis - Janneke de Winter

CHAPTER SIX
ABSTRACT
Objectives
We aimed to assess mRNA expression of MHC class 1 related molecules in ankylosing spondylitis (AS) versus healthy controls (HC) and subsequently if absence of HLA-C*07 is associated with genetic susceptibility to axial spondyloarthritis (axSpA).
Methods
HLA-C*07 was assessed in a) an exploratory cohort of 24 AS patients versus 40 HC, b) a confirmatory cohort of 113 AS patients and 83 non-radiographic axSpA patients from the GErman SPondyloarthritis Inception Cohort (GESPIC) versus 134,528 German potential stem cell donors, and c) an early back pain cohort with 94 early axSpA patients versus 216 chronic back pain (CBP) patients from the SPondyloArthritis Caught Early (SPACE) cohort.
Results
In the exploratory cohort, 79% of the AS patients were HLA-C*07 negative compared to 35% of the HC (p<0.001). This difference was confirmed in GESPIC with 73% of AS patients being HLA-C*07 negative compared to 50% of the controls (p<0.0001); 59% of the nr-axSpA patients were HLA-C*07 negative. In the SPACE cohort, 70% of axSpA patients were HLA-C*07 negative compared to 44% of CBP patients (p<0.0001); the association between HLA-C*07 negativity and a diagnosis of axSpA was independent from HLA-B*27. Exploratory analyses in GESPIC and SPACE suggest that HLA-C*07 negativity in axSpA is associated with increased inflammatory serum markers, radiographic damage, and absence of psoriasis.
Conclusion
The absence of HLA-C*07 is associated with genetic susceptibility to axSpA, independently of HLA-B*27. HLA-C*07 status is possibly linked to an axSpA phenotype with high inflammation and radiographic damage and with a low psoriasis prevalence.
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