The gut-enthesis axis and the pathogenesis of Spondyloarthritis

Subclinical inflammation is associated with Spondylarthritis (SpA). SpA patients show features of dysbiosis, altered gut barrier function, and local expansion of innate and innate-like cells involved in type 3 immune response. The recirculation of intestinal primed immune cells into the bloodstream and, in some cases, in the joints and the inflamed bone marrow of SpA patients gave the basis of the gut-joint axis theory. In the light of the critical role of enthesis in the pathogenesis of SpA and the identification of mucosal-derived immune cells residing into the normal human enthesis, a gut-enthesis axis is also likely to exist. This work reviews the current knowledge on enthesis-associated innate immune cells' primary involvement in enthesitis development, questions their origin, and critically discusses the clues supporting the existence of a gut-enthesis axis contributing to SpA development.

Peripheral arthritis and higher disease activity lead to more functional impairment in axial spondyloarthritis: Longitudinal analysis from ESPAXIA

OBJETIVE

The aim of this study was to investigate whether peripheral arthritis together with disease activity independently contribute to functional impairment over time in patients with axSpA and to evaluate if there are contextual factors modifying this relationship.

MATERIAL AND METHODS

Patients with axial spondyloarthritis from the ESPAXIA cohort were followed-up annually over a mean of 3.7 years. Physical function was assessed by the self-reported questionnaire BASFI, disease activity by ASDAS and peripheral arthritis was also recorded. Generalized estimating equations (GEE) were used to investigate longitudinal association between peripheral arthritis, ASDAS and BASFI as the outcome. Autoregressive models (adjusted for BASFI 1 year earlier) were run to allow for a truly longitudinal interpretation. Interactions between each of ASDAS and peripheral arthritis with contextual factors (age, gender, educational level, smoking, job type) were tested.

RESULTS

185 patients (77 % male, mean (SD) age 42 (13) years old and mean disease duration (SD) of 9.4 (9.6) years) were included. ASDAS and peripheral arthritis independently contributed to explaning BASFI over time. Contextual factors did not modify either of the relationships. A true longitudinal relation was proven with the autoregressive GEE model, showing that, adjusted for age, gender, spinal mobility and use of NSAIDs, an increase of one ASDAS unit led to a BASFI 0.48 units higher (ß 0.48 [95%CI 0.39, 0.57]), and the presence of peripheral arthritis, to a BASFI 0.44 units higher (ß 0.44 [95%CI 0.08, 0.8]).

CONCLUSION

Peripheral arthritis and higher disease activity independently lead to more functional impairment in axSpA over time. Contextual factors do not modify these relationships.