COMPLICATIONS - INFECTIONS

E.M. Dons¹, C. Montoya¹, E. Klein², G.J. Echeverri¹, R.F. Wolf³, J.N.M. Ijzermans⁴, R. Wagner², D.K.C. Cooper^1
1Department Of Surgery, Thomas E. Starzl Transplantation Intitute, University of Pittsburgh, Pittsburgh/UNITED STATES OF AMERICA, ²Division Of Laboratory Animal Resources, University of Pittsburgh, Pittsburgh/PA/UNITED STATES OF AMERICA, ³Comparative Medicine, Oklahoma University Health Sciences Center, Oklahoma/UNITED STATES OF AMERICA, ⁴General Surgery, Erasmus MC, Rotterdam/NETHERLANDS

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Introduction: Collagenous colitis is a chronic inflammatory bowel disease of unknown etiology, presenting with chronic watery diarrhea. The disease is mainly localized to the colon and rectum, and is characterized by a normal appearance of the mucosa on endoscopy and radiology, but with distinct histopathological changes seen on microscopic examination. Case Reports: We report 4 young baboons (age 7-12 months) that had been receiving immunosuppressive therapy (anti-CD154mAb, 25 mg/kg/week i.v. and mycophenolate mofetil, 50 – 150 mg/kg/2xdaily p.o.) for periods of 4-10 months. All baboons had received an artery patch graft from either another baboon (allograft) or a pig (xenograft) at 3 months of age. All presented identical symptoms within a period of 6 weeks, including weight loss associated with chronic watery diarrhea that was unresponsive to standard antimicrobial treatment. Clinical chemistry evaluations were within normal ranges, and fecal as well as blood cultures were repeatedly negative. One baboon died and one was euthanized for severe dehydration that could not be improved by fluid replacement; at necropsy, both were found to have a collagenous colitis. In the remaining two baboons that had identical clinical features of colitis, immunosuppressive therapy was discontinued and treatment with budesonide was initiated; this orally-administered non-absorbed steroid has efficacy in the terminal ileum and colon. A colonoscopy carried out in one of the two symptomatic infants was inconclusive as biopsies did not include layers deeper than the mucosa. Both baboons recovered and remain well on no medication 12 months later. Conclusion: Collagenous colitis is a chronic inflammatory bowel disease that is fairly common in adult humans, but rare in infants. In humans, it presents mainly in elderly women, and is associated with autoimmune disorders. It is not commonly associated with an immunocompromised state, though it has been reported occasionally in patients with organ transplants. It has been reported only once previously in baboons. The 4 cases reported here strongly suggest that (i) it was associated with the immunocompromised state of the baboons, as 2 non-immunosuppressed age-matched baboons in close proximity did not develop the condition, and (ii) it may have had an infectious origin as all 4 cases developed within a 6 week period of time, even though the ages of the baboons differed significantly, as did the periods of time they had been receiving immunosuppressive therapy.

Disclosure: All authors have declared no conflicts of interest.