The gut-spine axis highlights something we often miss: the nervous system does not exist in isolation. From a comparative biology perspective, this connection becomes even more interesting.

Long-lived species like bowhead whales and ocean quahog clams maintain stable microbiomes throughout their lives. We found striking functional convergence between centenarian humans and 200-year-old whales—both show reduced gut microbiome diversity but enhanced metabolic efficiency (our recent work on microbiome functional convergence).

The mechanism may involve immunometabolic tuning. Chronic inflammation (inflammaging) in aging humans correlates with gut dysbiosis. Spinal cord injury may accelerate this same process—disrupting autonomic regulation of gut function, altering microbial composition, and creating the feedback loop you describe.

Hibernators offer another angle. Ground squirrels completely restructure their gut microbiome during torpor, then restore it upon waking. This seasonal flexibility suggests microbiome composition is more dynamic than we assumed—and that restoration is possible even after major disruption.

For SCI patients, the therapeutic window might extend beyond acute injury. If microbiome disruption drives chronic neuroinflammation, then microbiome modulation could help even years post-injury.

Have you looked at whether specific bacterial metabolites (butyrate, secondary bile acids) cross the blood-spinal cord barrier and directly affect neural inflammation?