The TransplantLines Biobank and Cohort Study (NCT03272841) is an ongoing prospective study conducted at the University Medical Centre Groningen, The Netherlands. TransplantLines aims to identify risk factors and biomarkers associated with health problems following solid organ transplantation and donation. Additionally, the study seeks to develop new interventions to reduce symptom burden and improve long-term outcomes, including health-related quality of life, cardiovascular complications, graft failure, and mortality. It includes recipients of (combined) heart, liver, lung, kidney, pancreas, and small bowel transplants, as well as living liver and kidney donors, and deceased (multi-)organ donors. The biobank contains a wide range of biomaterials including whole blood, serum, EDTA-plasma, buffy coat, 24-h urine samples, faeces, hair, nails, and tissues. Data collection includes physical and cognitive assessments, extensive laboratory analysis, metagenomic sequencing, and questionnaires. TransplantLines, initiated in 2015, consists of 5143 participants as of October 2024, among 2312 (45%) females. The mean age was 50 (± 16) years at transplantation, 55 (± 11) years at living donation and 56 (± 15) years at deceased donation. Both cross-sectional and longitudinal biomaterials and data are included. For recipients, longitudinal biomaterials and data were collected at: pre-transplantation, at transplantation, and at 3, 6, 12, 24, and 60 months post-transplantation. For living donors, data were collected at pre-donation, donation, 3 months post-donation, and/or 5 or 10 years post-donation.

Torque Teno Virus (TTV) is a non-pathogenic virus that is highly prevalent among kidney transplant recipients (KTRs). Its circulating load is associated with an immunological status in KTR and is considered a promising tool for guiding immunosuppression. To allow for optimal guidance, it is important to identify other determinants of TTV load. We aimed to investigate the potential association of smoking and alcohol intake with TTV load. For this cross-sectional study, serum TTV load was measured using PCR in stable kidney transplant recipients at ≥1 year after transplantation, and smoking status and alcohol intake were assessed through questionnaires and measurements of urinary cotinine and ethyl glucuronide. A total of 666 KTRs were included (57% male). A total of 549 KTR (82%) had a detectable TTV load (3.1 ± 1.5 log₁₀ copies/mL). In KTR with a detectable TTV load, cyclosporin and tacrolimus use were positively associated with TTV load (St. β = 0.46, p < 0.001 and St. β = 0.66, p < 0.001, respectively), independently of adjustment for potential confounders. Current smoking and alcohol intake of >20 g/day were negatively associated with TTV load (St. β = −0.40, p = 0.004 and St. β = −0.33, p = 0.009, respectively), independently of each other and of adjustment for age, sex, kidney function, time since transplantation and calcineurin inhibitor use. This strong association of smoking and alcohol intake with TTV suggests a need to account for the smoking status and alcohol intake when applying TTV guided immunosuppression in KTR.

Key Points: Low-dose tacrolimus, everolimus, and prednisolone did not result in a higher rate of successful transplantation in older kidney transplant recipients. Low-dose tacrolimus, everolimus, and prednisolone did not result in better kidney function or fewer infections in older kidney transplant recipients. Background: We hypothesized that older kidney transplant recipients receiving low-dose tacrolimus, everolimus, and prednisolone (TEP) have better outcomes than patients receiving standard-dose tacrolimus, mycophenolate mofetil, and prednisolone (TMP). Methods: The OPTIMIZE study was a randomized clinical trial in kidney transplant recipients age ≥65 years. Patients receiving a kidney from a deceased donor older than 65 years (stratum A) or a kidney from a deceased donor younger than 65 years or a living donor (stratum B) were included. Patients were randomized to TEP or TMP groups. Tacrolimus target trough levels in the TEP group were 5–7 ng/ml until 3 months, 2–4 ng/ml from 3 to 6 months, and 1.5–4 ng/ml from 6 months onwards. Tacrolimus target trough levels in the TMP group were 8–12, 6–10, and 5–8 ng/ml. Everolimus target trough levels were 3–6 µ g/L. The primary end point of successful transplantation was defined as being alive with a functioning graft with an eGFR above a predefined threshold at 2 years after transplantation. Predefined eGFR thresholds were 30 (stratum A) or 45 ml/min per 1.73 m ² (stratum B). Results: A total of 379 patients were randomized, of whom 198 were in stratum A (TEP 97, TMP 101) and 181 in stratum B (TEP 90, TMP 91). The median trough levels for everolimus and tacrolimus were within the target range throughout the study. There was no statistically significant difference in successful transplantation at 2 years between the groups (TEP 94 [50%], TMP 110 [57%]; difference 7% [95% confidence interval, −17 to 3] P = 0.91). Regarding the predefined secondary outcomes, patient survival (TEP 167 [89%], TMP 171 [89%]; P = 0.95) and graft survival (TEP 155 [83%], TMP 162 [84%]; P = 0.65) did not differ significantly. Within strata A and B, there were no significant differences in the end points. Conclusions: Immunosuppression with low-dose tacrolimus, everolimus, and prednisolone did not result in a higher rate of successful transplantation in de novo older kidney transplant recipients compared with immunosuppression with standard-dose TMP. Clinical Trial registry name and registration number: ClinicalTrials.gov, NCT03797196.

Torque teno virus (TTV) is emerging as a potential marker for monitoring immune status. In transplant recipients who are immunosuppressed, higher TTV DNA loads are observed than in healthy individuals. TTV load measurement may aid in optimizing immunosuppressive medication dosing in solid organ transplant recipients. Additionally, there is a growing interest in the role of HDL particles in immune function; therefore, assessment of both HDL concentrations and TTV load may be of interest in transplant recipients. The objective of this study was to analyze TTV loads and HDL parameters in serum samples collected at least one year post-transplantation from 656 stable outpatient kidney transplant recipients (KTRs), enrolled in the TransplantLines Food and Nutrition Cohort (Groningen, the Netherlands). Plasma HDL particles and subfractions were measured using nuclear magnetic resonance spectroscopy. Serum TTV load was measured using a quantitative real-time polymerase chain reaction. Associations between HDL parameters and TTV load were examined using univariable and multivariable linear regression. The median age was 54.6 [IQR: 44.6 to 63.1] years, 43.3% were female, the mean eGFR was 52.5 (±20.6) mL/min/1.73 m² and the median allograft vintage was 5.4 [IQR: 2.0 to 12.0] years. A total of 539 participants (82.2%) had a detectable TTV load with a mean TTV load of 3.04 (±1.53) log10 copies/mL, the mean total HDL particle concentration was 19.7 (±3.4) μmol/L, and the mean HDL size was 9.1 (±0.5) nm. The univariable linear regression revealed a negative association between total HDL particle concentration and TTV load (st.β = −0.17, 95% CI st.β: −0.26 to −0.09, p < 0.001). An effect modification of smoking behavior influencing the association between HDL particle concentration and TTV load was observed (P_interaction = 0.024). After adjustment for age, sex, alcohol intake, hemoglobin, eGFR, donor age, allograft vintage and the use of calcineurin inhibitors, the negative association between HDL particle concentration and TTV load remained statistically significant in the non-smoking population (st.β = −0.14, 95% CI st.β: −0.23 to −0.04, p = 0.006). Furthermore, an association between small HDL particle concentration and TTV load was found (st.β = −0.12, 95% CI st.β: −0.22 to −0.02, p = 0.017). Higher HDL particle concentrations were associated with a lower TTV load in kidney transplant recipients, potentially indicative of a higher immune function. Interventional studies are needed to provide causal evidence on the effects of HDL on the immune system.