Anatomic predilection of the spondyloarthropathies(-)a case of the nerves?

Gastrointestinal (GI) and genitourinary (GU) inflammation are associated with arthritis of the joints of the lower extremities and lumbosacral spine. Some contemporary models assert that bacterial antigens or immune complexes are released from the viscera and circulate to the joints, inciting inflammation there. Others propose an autoimmune process directed against native joint antigens. However, neither paradigm explains the predilection of such arthritides for specific joints. Recent investigations have shown that peptidergic nerves supplying these joints project to the same spinal segments as those supplying the GI and GU tracts. The peptides released by these nerves act both as neurotransmitters at the nerves' central terminals and as inflammatory mediators at their peripheral terminals. I hypothesize that circuits of peptidergic nerves can transmit signals from abdominal and pelvic viscera to lumbosacrally innervated joints via the spinal cord, predisposing them to arthritis.