Effect of Integrin Blockade on Experimental Spondyloarthritis.

Spondyloarthritis (SpA) describes a group of diseases characterized by chronic inflammation in the spine and peripheral joints. While pathogenesis is still unclear, proinflammatory gut-derived immune cells have been identified in the joints of SpA patients. We previously identified an enriched population of integrin-expressing cells in the joints of SpA patients. Entry of gut-derived cells into joints may be mediated by these integrins. In the current study, we used the SKG murine model of SpA to study the impact of integrin blockade. Mice were injected with antibodies against the integrin α4β7 or the β7 monomer twice a week. Treatment with antibodies against α4β7 reduced disease severity in curdlan-injected SKG mice, with disease scores being comparable between treatment initiation times. Targeting the β7 monomer led to reduced arthritis severity compared to targeting the α4β7 dimer. Treatment with antibodies against α4β7 or β7 decreased expression of these integrins in CD4+ T cells, with the frequency of αE+β7+ T cells in the spleen and lymph nodes correlating with disease severity. In summary, we showed that integrin blockade showed potential for ameliorating disease in a murine model of SpA, lending support for further studies testing integrin blockade in SpA.