Mammalian models of extended healthy lifespan

Over the last two centuries, there has been a significant increase in average lifespan expectancy in the developed world. One unambiguous clinical implication of getting older is the risk of experiencing age-related diseases including various cancers, dementia, type-2 diabetes, cataracts and osteoporosis. Historically, the ageing process and its consequences were thought to be intractable. However, over the last two decades or so, a wealth of empirical data has been generated which demonstrates that longevity in model organisms can be extended through the manipulation of individual genes. In particular, many pathological conditions associated with the ageing process in model organisms, and importantly conserved from nematodes to humans, are attenuated in long-lived genetic mutants. For example, several long-lived genetic mouse models show attenuation in age-related cognitive decline, adiposity, cancer and glucose intolerance. Therefore, these long-lived mice enjoy a longer period without suffering the various sequelae of ageing. The greatest challenge in the biology of ageing is to now identify the mechanisms underlying increased healthy lifespan in these model organisms. Given that the elderly are making up an increasingly greater proportion of society, this focused approach in model organisms should help identify tractable interventions that can ultimately be translated to humans

Combined liver-kidney transplantation: Analysis of patients with preformed lymphocytotoxic antibody

In this report, we address combined liver-kidney transplantation, with particular attention to the apparent phenomenon of protection of kidney allografts to antibody mediated destruction by liver allografts. Four patients were found to have positive crossmatch before the liver phase of the combined transplant (pre-OT/KT samples). These positive crossmatches were due entirely to anti-HLA class I antibodies, as demonstrated by their removal by immunoabsorption on pololed platelets. In three of these patients, post-OT/pre-KT samples showed a conversion to a negative crossmatch (in the fourth patient this was not done). A kidney allograft, harveted from the same donor, was then placed into the recipient, and in patients no. 3, 7, and 12, good initial function was noted. In one of these patients was there evidence of hyperacute rejection. Post-OT/KT samples were collected in patients no. 3, 7, and 8, and then analyzed for the reappearance of donor specific lymphocytotoxic antibodies in the posttransplant period (data on patient no. 12 was not available at time of preparation). Lymphocytotoxic antibodies with donor specificity could not be detected in any of the samples during the first week posttransplant. The decrease in %PRA and conversion of a positive to negative crossmatch following liver transplantation was correlated to the HLA specificty of the antibody found in the pretransplant serum and the HLA type of the tranplanted organs. In the two instances where an HLA specificity could be determined by panel analysis, transplantation with donor organs bearing these HLA specificities led to a specific disppearance of these antibodies during the postransplant phase

Population Frequencies Determined by Next-generation Sequencing Provide Strategies for Prospective HLA Epitope Matching for Transplantation

Compatibility for human leukocyte antigen (HLA) genes between transplant donors and recipients improves graft survival but prospective matching is rarely performed due to the vast heterogeneity of this gene complex. To reduce complexity, we have combined next-generation sequencing and in silico mapping to determine population frequencies and matching probabilities of 150 antibody-binding eplets across all 11 classical HLA genes in 2000 ethnically heterogeneous renal patients and donors. We show that eplets are more common and more uniformly distributed between donors and recipients than the respective HLA isoforms. Simulation of targeted eplet matching shows that a high degree of overall compatibility, and perfect identity at the clinically important HLA class II loci, can be obtained within a patient waiting list of approximately 250 subjects. Internal epitope-based allocation is thus feasible for most major renal transplant programs, while regional or national sharing may be required for other solid organs