Chlamydia Pneumoniae Infection Accelerates Rat Cardiac Allograft Chronic Rejection But Does Not Impact Graft Survival In The Absence Of Alloreactivity

Chlamydia pneumoniae (Cpn) infection has been associated with graft chronic rejection (CR) in human heart and liver transplant recipients, though the high frequency of human Cpn infection confounds such studies. Therefore, we tested whether Cpn infection accelerates CR in a rat cardiac allograft model. F344 rat hearts were heterotopically transplanted into Lewis recipients, either treated with CsA or previously made chimeric with F344 bone marrow cells. Cpn administration resulted in disseminated infection. The allografts were palpated daily until pulsation was no longer detectable (graft failure), or post‐operative day (POD) 120 (maximum study length). F344 allografts in Lewis recipients infected with Cpn on POD 1, POD 7, or PODs 1 and 19 failed significantly earlier than those in the control group. Preexisting recipient infection also significantly accelerated CR, while preexisting donor infection did not accelerate CR. Accelerated CR required infectious Cpn. Chimeric Lewis rat recipients rejected third party allografts, but did not reject F344 allografts regardless of recipient Cpn infection. Therefore rat cardiac allograft recipient Cpn infection, either prior to, at the time of, or a week following transplantation, accelerates CR but does not impact graft survival in the absence of alloreactivity. Supported by Merit Review Funds, Dept. of Veterans Affairs.