IntroductionIn the past decades, short-term results after solid organ transplantation have markedly improved. Disappointingly, this has not been accompanied by parallel improvements in long-term outcomes after transplantation. To improve graft and recipient outcomes, identification of potentially modifiable risk factors and development of biomarkers are required. We provide the rationale and design of a large prospective cohort study of solid organ transplant recipients (TransplantLines).Methods and analysisTransplantLines is designed as a single-centre, prospective cohort study and biobank including all different types of solid organ transplant recipients as well as living organ donors. Data will be collected from transplant candidates before transplantation, during transplantation, at 3 months, 6 months, 1 year, 2 years and 5 years, and subsequently every 5 years after transplantation. Data from living organ donors will be collected before donation, during donation, at 3 months, 1 year and 5 years after donation, and subsequently every 5 years. The primary outcomes are mortality and graft failure. The secondary outcomes will be cause-specific mortality, cause-specific graft failure and rejection. The tertiary outcomes will be other health problems, including diabetes, obesity, hypertension, hypercholesterolaemia and cardiovascular disease, and disturbances that relate to quality of life, that is, physical and psychological functioning, including quality of sleep, and neurological problems such as tremor and polyneuropathy.Ethics and disseminationEthical approval has been obtained from the relevant local ethics committee. The TransplantLines cohort study is designed to deliver pioneering insights into transplantation and donation outcomes. The study design allows comprehensive data collection on perioperative care, nutrition, social and psychological functioning, and biochemical parameters. This may provide a rationale for future intervention strategies to more individualised, patient-centred transplant care and individualisation of treatment.Trial registration number NCT03272841.

Organ transplantation is a life-saving treatment for patients with end-stage disease, but survival rates after transplantation vary considerably. There is now increasing evidence that the gut microbiome is linked to the survival of patients undergoing hematopoietic cell transplant, yet little is known about the role of the gut microbiome in solid organ transplantation. We analyzed 1370 fecal samples from 415 liver and 672 renal transplant recipients using shotgun metagenomic sequencing to assess microbial taxonomy, metabolic pathways, antibiotic resistance genes, and virulence factors. To quantify taxonomic and metabolic dysbiosis, we also analyzed 1183 age-, sex-, and body mass index–matched controls from the same population. In addition, a subset of 78 renal transplant recipients was followed longitudinally from pretransplantation to 24 months after transplantation. Our data showed that both liver and kidney transplant recipients suffered from gut dysbiosis, including lower microbial diversity, increased abundance of unhealthy microbial species, decreased abundance of important metabolic pathways, and increased prevalence and diversity of antibiotic resistance genes and virulence factors. These changes were found to persist up to 20 years after transplantation. Last, we demonstrated that the use of immunosuppressive drugs was associated with the observed dysbiosis and that the extent of dysbiosis was associated with increased mortality after transplantation. This study represents a step toward potential microbiome-targeted interventions that might influence the outcomes of recipients of solid organ transplantation.

10 (4) Systolic blood pressure, mm Hg 134 AE 17 136 AE 16 137 AE 19 0.18 Diastolic blood pressure, mm Hg 83 AE 11 83 AE 11 82 AE 11 0.60 Use of antihypertensive medication 187 (84) 197 (89) 208 (92) 0.02 Dietary intake Total energy intake, kcal/d 2259 AE 633 2088 AE 634 2152 AE 587 0.45 Cereals, g/d 187 (147-231) 176 (146-211) 178 (138-212) 0.21 Potatoes, g/d 111 (70-146) 118 (73-166) 122 (76-173) 0.29 Vegetables, g/d 80 (56-116) 80 (48-124) 75 (53-107) 0.54 Fruits, g/d 100 (48-189) 110 (53-197) 104 (39-186) 0.22 Legumes, g/d 29 (14-48) 30 (18-45) 31 (17-43) 0.88 Nuts, g/d 5.