This study was a prospective one-centre analysis that included patients (Caucasians) older than 18 years that had undergone primary transplantation of the kidney in the Martin (2018-2019), Slovakia Transplantation Center. Patients with diabetes mellitus diagnosed prior to the kidney transplantation, patients with complicated or protracted infection, including secondary wound healing, and patients with a medical history of oncology illness were excluded from the monitoring (Figure 1). Patients who did not complete the 3-month follow-up and patients who did not undergo protocol biopsy or whose protocol biopsy result was not representative were also excluded from the monitoring. One hundred four patients who met the criteria were thus included in the study.
Immunosuppression and induction
All patients included in the monitored group received induction according to the protocol of the Martin Transplantation Center using the anti-thymocyte globulin in a total dosage of 3.5 mg/kg (divided into three doses: day 0, day 1, day 2). The criteria for induction with the anti-thymocyte globulin are: panel reactive antibodies more then 10%, history of positive cross match test, dialysis program more than 5 years, cold ischemia time more then 18 hours or expanded criteria donor. The maintenance immunosuppression consisted of tacrolimus and mycophenolic acid (1080 mg daily dose until the 2nd week after the transplantation, followed by a 720 mg daily dose). Methylprednisolone 500 mg i.v. was administered on day 0 and day 1, followed by the administration of Prednisone 20 mg until the 2nd week after the transplantation, Prednisone 15 mg until the 4th week after the transplantation, Prednisone 10 mg until the 12th week after the transplantation, and Prednisone 7.5 mg until the 12th month after the transplantation, with Prednisone 5 mg administered daily thereafter
Adipocytokines and interleukins
We determined the leptin, adiponectin, IL-6, and IL-10 values of each patient prior to the transplantation (2 hours before the surgery) and in the 3rd month after the transplantation. The Human Total Adiponectin ELISA Kit, Human Leptin Quantikine ELISA kit, LEGEND MAX Human IL-6 ELISA Kit, and the LEGEND MAX Human IL-10 Kit were used for examination. Hyperleptinaemia was determined when the leptin value was higher than 77 μg/ml. Hypoadiponectinaemia was determined when the leptin value was lower than 9 µg/ml (based on reference values determined by the manufacturer of the kits used). Hyper-IL-6 was determined when the IL-6 value was higher than 6.4 pg/ml, and hypo-IL-10 was determined when the IL-10 value was lower than 2.8 pg/ml.
Other monitored parameters
We determined the average tacrolimus (TAC) level for 3 months for all patients. We also recorded the estimated glomerular filtration rate (eGFR) (according to the CKD-EPI formula) at the time of sampling adipocytokines and interleukins. We monitored the body mass index (BMI), waist circumference (baseline, and month 3 [M3]), and lipid metabolism parameters of all patients (Table 1).
Protocol biopsy and monitoring of donor-specific antibodies (DSA)
Protocol graft biopsy and the determination of donor-specific antibodies was performed in the 3rd month for all patients included in the study by means of the LUMINEX methodology (positivity was stipulated at ≥500 MFI). We further divided the group according to the result of the protocol biopsy (according to the Banff classification 2019) into groups with a negative result, interstitial fibrosis and tubular atrophy (IFTA), borderline changes (t1-t3 with i1 or t1 with i2 or i3), and group with positive donor specific antibodies. We did not observed changes in the character of T-cell-mediated rejection (TCMR) and antibody-mediated rejection (ABMR) in the monitored group. The IFTA group included only patients meeting criteria for IFTA 1).
Statistical analysis
We used a certified statistical program, MedCalc version 13.1.2. (VAT registration no. BE 0809 344 640, Member of International Association of Statistical Computing, Ostend, Belgium), to perform statistical analyses. Continuous data were compared using the Student’s t-test or the Wilcoxon rank-sum test as appropriate. The χ2 test and Fisher’s exact test were used for categorical variables. The Cox proportional hazards model was used to adjust for the differences in baseline recipient (such as age, gender, HLA mismatch, panel reactive antibodies - PRA, and time in dialysis program) and donor characteristics (cold ischemia time - CIT, expanded criteria donor - ECD) on the endpoint of rejection. ROC curve analysis was used for leptinaemia 3M and rejection and IL-10 and rejection. We considered a P-value of <0.05 to be statistically significant.
Ethical approval
All procedures involving human participants have been approved according to the ethical standards of the institutional research committee, including the 1964 Helsinki Declaration and its later amendments of comparable ethical standards. Informed consent for included participants was checked and approved by University hospital's and Jessenius Faculty of Medicine's ethical committees and all signed informed consents have been archived for at least 20 years after research was completed.
The clinical and research activities being reported are consistent with the Principles of the Declaration of Istanbul as outlined in the Declaration of Istanbul on Organ Trafficking and Transplant Tourism.