Abrogation of Chronic Rejection in a Murine Model of Aortic Allotransplantation by Prior Induction of Donor-Specific Tolerance1

Abstract

Aortic allotransplantation in mice has been well established as a model of choice to study the evolvement of chronic rejection, the etiopathology of which is believed to be that of immune origin. This has prompted the postulation that prior induction of donor-specific tolerance would attenuate or abrogate the underlying events that culminate in posttransplant arteriosclerosis. To study the effects of donor-specific tolerance on chronic rejection, we performed orthotopic liver transplantation without immunosuppression in mice 30 days before aortic allotransplantation across C57Bl/10J (H2 b )→C3H (H2 k ) strain combinations (group III. Aortic allografting in syngeneic (group I; C3H→C3H) and allogeneic (group II, C57Bl/10J→C3H) animals served as controls. No morphological changes were evidenced in the transplanted aortas in group I animals. Contrarily, aortic allografts in group II animals underwent a self-limiting acute cellular rejection, which resolved completely and was succeeded by day 30 after transplantation by histopathological changes pathognomonic of chronic rejection. There was evidence for diffuse myointimal thickening, progressive concentric luminal narrowing, and patchy destruction of internal elastic membranes resulting in massive vascular obliteration by day 120 after transplantation. It was of interest that no arteriosclerotic changes were observed for the duration of follow-up (up to 120 days after transplantation) in transplanted aortas (liver donor-type) harvested from animals in group III. However, vasculopathy was prominent in third-party aortic grafts transplanted into tolerant recipients. Taken together, these data suggest that prior induction of tolerance abrogates the development of chronic rejection; this protection seems to be donor specific.The most common cause for late organ allograft failure is chronic rejection (CR * ); its incidence in organs surviving more than 5 years is up to 43%, 50%, and 60% for transplanted kidneys (1), lungs (2), and hearts (3), respectively. Conversely, its prevalence is much lower (3.6-16.8%) in long-surviving liver allografts (4). Although the factors underlying the changes pathognomonic of posttransplant obliterative vasculopathy are poorly understood, they nevertheless seem to be multifactorial (5-7). In addition to ischemia-reperfusion, allogeneic

PREVENTION OF CHRONIC REJECTION IN MOUSE AORTIC ALLOGRAFTS BY COMBINED TREATMENT WITH CTLA4-Ig AND ANTI-CD40 LIGAND MONOCLONAL ANTIBODY1,2

“…As reported previously (11,12), aortic allografts obtained at day 30 after transplantation from untreated recipients (group A) exhibited changes characteristic of CR (Fig. 2C).…”

“…2A). This observation was reminiscent of our previously published data in which prior induction of liver-induced, donor-specific tolerance also abrogated the development of CR (12).…”

“…AOTx across untreated syngeneic (C3H→C3H) animals served as an additional control. Allografts were harvested on day 30 after transplantation, when distinctive changes of CR are most evident (12).…”

“…In addition to hematoxylin and eosin staining (Surgipath, Richmond, IL), Verhoeff-van Gieson (elastic fibers) and Masson's trichrome (collagen) staining was also performed. Additionally, the presence of α-smA + cells was determined using a previously described method (12). Briefly, after hydration, endogenous-peroxidase activity was blocked by treating the sections for 45 min with 0.6% solution containing 71% methanol, 24% dH 2 O, and 5% H 2 O 2 After two washings, nonspecific binding was blocked by a 20-min incubation in Lipshaw Universal Protein Blocker and then a 45-min incubation with mouse α-human mAb directed against α-smA + cells; the sections were then washed two times with phosphate-buffered saline.…”

Accelerated reversal of carbon tetrachloride‐induced cirrhosis in rats by the endothelin receptor antagonist TAK‐044

“…The primary antibody was identified by biotinylated antimouse IgG (Vector Laboratories, Burlingame, CA, USA). For visualization of secondary antibody, the ABC immunoperoxidase system (VECTASTIN; Vector Laboratories) and chromogen‐3‐amino‐9‐ethylcarbazol (ScyTek Laboratories, Logan, UT, USA) were used 19 . Morphometric evaluation was performed by VMS, who was blinded to the study, using an established scoring system 20–23 as follows.…”