TNF and Sacroiliac arthritis: Indeed, using an established TNF transgenic murine model (which develops a SpA-like disease characterized by peripheral joint arthritis, sacroiliitis, enthesitis, and Crohn’s-like inflammatory bowel disease), it was shown that selective TNFRI expression in mesenchymal cells resulted in a fully arthritic–spondyloarthritic and intestinal phenotype [41].