Blood sample processing for the study of aging, and characterization of caspase mRNA expression in peripheral blood mononuclear cells

Centenarian population studies are one of several approaches currently used to study the aging process and characterize successful aging. I have described a methodology permitting the simultaneous generation of RNA, DNA, protein, and plasma samples, as well as fixed peripheral blood mononuclear cells (PBMC) and frozen blood aliquots, from a single 10- to 30-ml sample of peripheral blood obtained from donors of any age, and showed that although extremely old individuals are somewhat anemic, it is possible to obtain enough biological material from their blood to conduct aging studies.I investigated the possibility of immortalizing B-lymphocytes from extremely old individuals, using the Epstein-Barr virus (EBV), and found that although extremely old individuals (90+ years) possess low levels of circulating B-lymphocytes, it is possible to immortalize B cells present in less than one milliliter of their blood using EBV.Using biological material obtained from blood samples of individuals of all ages by the method for blood sample processing I have described, I studied the mRNA expression of cell death (specifically caspase) genes in nonagenarians and centenarians, successful models of aging who have survived or avoided age-associated diseases, as well as in their younger counterparts, to determine whether apoptotic genes may be part of the genetic determinants of longevity. I found that a population of extremely old individuals (90+) shows a unique pattern of caspase mRNA expression, characterized by high levels of caspase-1 and -3, and low levels of caspase-8, mRNA, while slightly less aged individuals (70--89) are characterized by high levels of caspase-8 mRNA expression. Furthermore, I showed that these changes in caspase mRNA do not appear to result from age-related changes in PBMC composition, such as decreases in CD24. Therefore, I suggest that unique patterns of caspase mRNA result from the regulation of message abundance on a per cell basis, via a putative regulation of caspase genes at the transcription or RNA processing level, rather than age-associated changes in immune profiles

Effect of donor HSD17B13 genotype on patient survival after liver transplant: a retrospective cohort studyResearch in context

Summary: Background: Several genetic variants are associated with chronic liver disease. The role of these variants in outcomes after liver transplantation (LT) is uncertain. The aim of this study was to determine if donor genotype at risk-associated variants in PNPLA3 (rs738409 C>G, p.I148M) and HSD17B13 (rs72613567 T>TA; rs80182459, p.A192Lfs∗8) influences post-LT survival. Methods: In this retrospective cohort study, data on 2346 adults who underwent first-time LT between January 1, 1999 and June 30, 2020 and who had donor DNA samples available at five large Transplant Immunology Laboratories in Texas, USA, were obtained from the United Network for Organ Sharing (UNOS). Duplicates, patients with insufficient donor DNA for genotyping, those who were <18 years of age at the time of transplant, had had a previous transplant or had missing genotype data were excluded. The primary outcomes were patient and graft survival after LT. The association between donor genotype and post-LT survival was examined using Kaplan–Meier method and multivariable-adjusted Cox proportional hazards models. Findings: Median age of LT recipients was 57 [interquartile range (IQR), 50–62] years; 837 (35.7%) were women; 1362 (58.1%) White, 713 (30.4%) Hispanic, 182 (7.8%) Black/African-American. Median follow-up time was 3.95 years. Post-LT survival was not affected by donor PNPLA3 genotype but was significantly reduced among recipients of livers with two HSD17B13 loss-of-function (LoF) variants compared to those receiving livers with no HSD17B13 LoF alleles (unadjusted one-year survival: 82.6% vs 93.9%, P < 0.0001; five-year survival: 73.1% vs 82.9%, P = 0.0017; adjusted hazard ratio [HR], 2.25; 95% CI, 1.61–3.15 after adjustment for recipient age, sex, and self-reported ethnicity). Excess mortality was restricted to those receiving steroid induction immunosuppression (crude 90-day post-LT mortality, 9.3% [95% CI, 1.9%–16.1%] vs 1.9% [95% CI, 0.9%–2.9%] in recipients of livers with two vs no HSD17B13 LoF alleles, P = 0.0012; age, sex, and ethnicity-adjusted HR, 2.85; 95% CI, 1.72–4.71, P < 0.0001). No reduction was seen among patients who did not receive steroid induction (90-day mortality 3.1% [95% CI, 0%–7.3%] vs 2% [95% CI, 0.9%–3.1%], P = 0.65; adjusted HR, 1.17; 95% CI, 0.66–2.08, P = 0.60). Interpretation: Donor HSD17B13 genotype adversely affects post-LT survival in patients receiving steroid induction. Additional studies are required to confirm this association. Funding: The National Institutes of Health and American Society of Transplant Surgeons Collaborative Scientist Gran