We have reported that lung allograft rejection involves an immune response to a native protein in the lung, type V collagen (col(V)), and that col(V)-induced oral tolerance prevented acute and chronic rejection. In support of these findings col(V) fragments were detected in allografts during rejection, but not in normal lungs. The purpose of the current study was to isolate and characterize col(V)-specific allograft-infiltrating T cells and to determine their contribution to the rejection response in vivo. Two col(V)-specific T cell lines, LT1 and LT3, were isolated from F344 (RT1lv1) rat lung allografts during rejection that occurred after transplantation into WKY (RT1l) recipients. Both cell lines, but not normal lung lymphocytes, proliferated in response to col(V). Neither LT1 nor LT3 proliferated in response to alloantigens. LT1 and LT3 were CD4+CD25− and produced IFN-γ in response to col(V). Compared with normal CD4+ T cells, both cell lines expressed a limited V-β TCR repertoire. Each cell strongly expressed V-β 9 and 16, but differed in expression of other V-βs. Adoptive transfer of each cell line did not induce pathology in lungs of normal WKY rats. In contrast, adoptive transfer of LT1, but not LT3, caused marked peribronchiolar and perivascular inflammation in isograft (WKY) lungs and abrogated col(V)-induced oral tolerance to allograft (F344) lungs. Collectively, these data show that lung allograft rejection involves both allo- and autoimmune responses, and graft destruction that occurs during the rejection response may expose allograft-infiltrating T cells to potentially antigenic epitopes in col(V).

Immunity to collagen V [col(V)] contributes to lung 'rejection.' We hypothesized that ischemia reperfusion injury (IRI

Obliterative bronchiolitis (OB) is the key impediment to the long-term survival of lung transplant recipients and the lack of a robust preclinical model precludes examining OB immunopathogenesis. In the current study, lungs from C57BL/10 H-2 b mice that are MHC compatible, but minor histocompatability antigen incompatible, were transplanted into C57BL/6 mice. Histological features and cytokine profiles of OB were assessed. Moderate rejection (grade A3) developed by day 14, with evidence of OB at that time point. At 21 days, OB was present in 55% of grafts and moderate to severe rejection (grade A3-A4) was present in all mice. At 28 days, OB was present in 44% of mice and severe rejection (grade A4) was present in all. IL-17A, but not IL-17F, splenic mRNA transcripts and serum protein levels were increased only in mice that developed OB, whereas IL-10 transcripts and protein were increased only in non-OB mice. Neutralizing IL-17 prevented OB, down regulated acute rejection, and upregulated systemic IL-10. Collectively, these data show that transplantation of minor histoincompatible lungs from C57BL/10 mice into C57BL/6 mice results in a highly reproducible preclinical model of OB. In addition, these data indicate that neutralizing IL-17A or augmenting IL-10 could be therapeutic interventions to prevent OB.

Immunization with specific proteins or peptides has been used to induce immunologic tolerance to allografts other than the lung. Recently, we have reported that the immune response to lung alloantigen also involves an immune response to type V collagen [col(V)]. The purpose of the current study was to determine if oral administration of col(V) to lung allograft recipients before transplantation downregulates acute rejection episodes. The data show that, compared with controls, col(V)-fed recipients had fewer polymorphonuclear cells and lymphocytes in allograft bronchoalveolar lavage fluid, and reduced rejection pathology. Data showing that col(V)- fed allograft recipients had diminished delayed-type hypersensitivity (DTH) responses to donor alloantigens suggest that feeding col(V) prevented allograft rejection by inducing tolerance to donor antigens. Systemic production of transforming growth factor (TGF)-beta, interleukin (IL)-4, or IL-10 has been reported to be a mechanism for oral tolerance-induced suppression of immune responses. Feeding col(V) induced upregulated production of TGF-beta, but not IL-4 or IL-10 in serum. Neutralizing TGF-beta recovered the DTH response to donor antigen in tolerant allograft recipients. Collectively, these data show that oral administration of col(V) is a novel approach to induce immunologic tolerance to lung allografts, and that TGF-beta contributed to suppression of the rejection response.