Inhibition of autoimmune Chagas-like heart disease by bone marrow transplantation.

BACKGROUND: Infection with the protozoan Trypanosoma cruzi manifests in mammals as Chagas heart disease. The treatment available for chagasic cardiomyopathy is unsatisfactory. METHODS/PRINCIPAL FINDINGS: To study the disease pathology and its inhibition, we employed a syngeneic chicken model refractory to T. cruzi in which chickens hatched from T. cruzi inoculated eggs retained parasite kDNA (1.4 kb) minicircles. Southern blotting with EcoRI genomic DNA digests revealed main 18 and 20 kb bands by hybridization with a radiolabeled minicircle sequence. Breeding these chickens generated kDNA-mutated F1, F2, and F3 progeny. A targeted-primer TAIL-PCR (tpTAIL-PCR) technique was employed to detect the kDNA integrations. Histocompatible reporter heart grafts were used to detect ongoing inflammatory cardiomyopathy in kDNA-mutated chickens. Fluorochromes were used to label bone marrow CD3+, CD28+, and CD45+ precursors of the thymus-dependent CD8α+ and CD8ß+ effector cells that expressed TCRγδ, vß1 and vß2 receptors, which infiltrated the adult hearts and the reporter heart grafts. CONCLUSIONS/SIGNIFICANCE: Genome modifications in kDNA-mutated chickens can be associated with disruption of immune tolerance to compatible heart grafts and with rejection of the adult host's heart and reporter graft, as well as tissue destruction by effector lymphocytes. Autoimmune heart rejection was largely observed in chickens with kDNA mutations in retrotransposons and in coding genes with roles in cell structure, metabolism, growth, and differentiation. Moreover, killing the sick kDNA-mutated bone marrow cells with cytostatic and anti-folate drugs and transplanting healthy marrow cells inhibited heart rejection. We report here for the first time that healthy bone marrow cells inhibited heart pathology in kDNA+ chickens and thus prevented the genetically driven clinical manifestations of the disease.

Heritable integration of kDNA minicircle sequences from Trypanosoma cruzi into the avian genome: insights into human Chagas disease.

We demonstrate the genetic transfer of DNA between eukaryotes from different kingdoms. The mitochondrial kinetoplast DNA (kDNA) of the intracellular parasite Trypanosoma cruzi is transferred to human patients with Chagas disease. This transfer was reproduced experimentally in rabbits and chickens. The kDNA is integrated into the host genome. In the human chromosomes, five loci were identified as integration sites, and the beta-globin locus and LINE-1 retrotransposons were frequently targeted. Short repeated sequences in the parasite and the target host DNAs favor kDNA integration by homologous recombination. Introduced kDNA was present in offspring of chronically infected rabbits and in chickens hatched from T. cruzi-inoculated eggs. kDNA incorporated into the chicken germline was inherited through the F2 generation in the absence of persistent infection. kDNA integration represents a potential cause for the autoimmune response that develops in a percentage of chronic Chagas patients, which can now be approached experimentally.