Combination of calcineurin and mTOR inhibitors in kidney transplantation: a propensity score analysis based on current clinical practice

Autophagy: A Silent Protagonist in Kidney Transplantation

Autophagy is a lysosome-dependent regulated mechanism that recycles unnecessary cytoplasmic components. It is now known that autophagy dysfunction may have a pathogenic role in several human diseases and conditions, including kidney transplantation. Both defective and excessive autophagy may induce or aggravate several complications of kidney transplantation, such as ischemia-reperfusion injury, alloimmune response, and immunosuppressive treatment and side effects. Although it is still complicated to measure autophagy levels in clinical practice, more attention should be paid to the factors that may influence autophagy. In kidney transplantation, the association of low doses of a mammalian target of rapamycin inhibitor with low doses of a calcineurin inhibitor may be of benefit for autophagy modulation. However, further studies are needed to explore the role of other autophagy regulators.

Effectiveness and safety of immunosuppressive regimens used as maintenance therapy in kidney transplantation: The CESIT study

Maintenance immunosuppressive therapy used in kidney transplantation typically involves calcineurin inhibitors, such as tacrolimus or cyclosporine, in combination with mycophenolate or mechanistic target of rapamycin (mTORi) with or without corticosteroids. An Italian retrospective multicentre observational study was conducted to investigate the risk-benefit profile of different immunosuppressive regimens. We identified all subjects who underwent kidney transplant between 2009 and 2019, using healthcare claims data. Patients on cyclosporine and tacrolimus-based therapies were matched 1:1 based on propensity score, and effectiveness and safety outcomes were compared using Cox models (HR; 95%CI). Analyses were also conducted comparing mTORi versus mycophenolate among tacrolimus-treated patients. Patients treated with cyclosporine had a higher risk of rejection or graft loss (HR:1.69; 95%CI:1.16-2.46) and a higher incidence of severe infections (1.25;1.00-1.55), but a lower risk of diabetes (0.66;0.47-0.91) compared to those treated with tacrolimus. Among tacrolimus users, mTORi showed non-inferiority to MMF in terms of mortality (1.01;0.68-1.62), reject/graft loss (0.61;0.36-1.04) and severe infections (0.76;0.56-1.03). In a real-life setting, tacrolimus-based immunosuppressive therapy appeared to be superior to cyclosporine in reducing rejection and severe infections, albeit with an associated increased risk of diabetes. The combination of tacrolimus and mTORi may represent a valid alternative to the combination with mycophenolate, although further studies are needed to confirm this finding.

Hyperglycemia and Hyperlipidemia with Kidney or Liver Transplantation: A Review

Although solid organ transplantation in persons with diabetes mellitus is often associated with hyperglycemia, the risk of hyperlipidemia in all organ transplant recipients is often underestimated. The diagnosis of diabetes often predates transplantation; however, in a moderate percentage of allograft recipients, perioperative hyperglycemia occurs triggered by antirejection regimens. Post-transplant prescription of glucocorticoids, calcineurin inhibitors and mTOR inhibitors are associated with increased lipid concentrations. The existence of diabetes mellitus prior to or following a liver transplant is associated with shorter times of useful allograft function. A cycle involving Smad, TGF beta, m-TOR and toll-like receptors has been identified in the contribution of rejection and aging of allografts. Glucocorticoids (prednisone) and calcineurin inhibitors (cyclosporine and tacrolimus) induce hyperglycemia associated with insulin resistance. Azathioprine, mycophenolate and prednisone are associated with lipogenesis. mTOR inhibitors (rapamycin) are used to decrease doses of atherogenic agents used for immunosuppression. Post-transplant medication management must balance immune suppression and glucose and lipid control. Concerns regarding rejection often override those relative to systemic and organ vascular aging and survival. This review focuses attention on the underlying mechanism of relationships between glycemia/lipidemia control, transplant rejection and graft aging.

Translation suppression underlies the restrained COVID-19 mRNA vaccine response in the high-risk immunocompromised group

Background

Immunocompromised (IC) patients show diminished immune response to COVID-19 mRNA vaccines (Co-mV). To date, there is no ‘empirical’ evidence to link the perturbation of translation, a rate-limiting step for mRNA vaccine efficiency (VE), to the dampened response of Co-mV.

Materials and methods

Impact of immunosuppressants (ISs), tacrolimus (T), mycophenolate (M), rapamycin/sirolimus (S), and their combinations on Pfizer Co-mV translation were determined by the Spike (Sp) protein expression following Co-mV transfection in HEK293 cells. In vivo impact of ISs on SARS-CoV-2 spike specific antigen (SpAg) and associated antibody levels (IgGSp) in serum were assessed in Balb/c mice after two doses (2D) of the Pfizer vaccine. Spike Ag and IgGSp levels were assessed in 259 IC patients and 50 healthy controls (HC) who received 2D of Pfizer or Moderna Co-mV as well as in 67 immunosuppressed solid organ transplant (SOT) patients and 843 non-transplanted (NT) subjects following three doses (3D) of Co-mV. Higher Co-mV concentrations and transient drug holidays were evaluated.

Results

We observed significantly lower IgGSP response in IC patients (p<0.0001) compared to their matched controls in 2D and 3D Co-mV groups. IC patients on M or S showed a profound dampening of IgGSP response relative to those that were not on these drugs. M and S, when used individually or in combination, significantly attenuated the Co-mV-induced Sp expression, whereas T did not exert significant influence. Sirolimus combo pretreatment in vivo significantly attenuated the Co-mV induced IgMSp and IgGSp production, which correlated with a decreasing trend in the early levels (after day 1) of Co-mV induced Sp immunogen levels. Neither higher Co-mV concentrations (6μg) nor withholding S for 1-day could overcome the inhibition of Sp protein levels. Interestingly, 3-days S holiday or using T alone rescued Sp levels in vitro.

Conclusions

This is the first study to demonstrate that ISs, sirolimus and mycophenolate inhibited Co-mV-induced Sp protein synthesis via translation repression. Selective use of tacrolimus or drug holiday of sirolimus can be a potential means to rescue translation-dependent Sp protein production. These findings lay a strong foundation for guiding future studies aimed at improving Co-mV responses in high-risk IC patients.

Outcomes in older kidney recipients from older donors: A propensity score analysis

Background

The age of patients referred for kidney transplantation has increased progressively. However, the precise influence of age on transplant outcomes is controversial.

Methods

Etrospective study in which graft and recipient survival were assessed in a cohort of ≥75 years old kidney recipients and compared with a contemporary younger one aged 60-65 years through a propensity score analysis.

Results

We included 106 recipients between 60-65 and 57 patients of ≥75 years old with a median follow-up of 31 [13-54] months. Unadjusted one- and five-year recipient survival did not significantly differ between the older (91% and 74%) and the younger group (95% and 82%, P=0.06). In the IPTW weighted Cox regression analysis, recipient age was not associated with an increased risk of death (HR 1.88 95%CI [0.81-4.37], P=0.14). Unadjusted one- and five-year death-censored graft survival did not significantly differ between both groups (96% and 83% for the older and 99% and 89% for the younger group, respectively, P=0.08). After IPTW weighted Cox Regression analysis, recipient age ≥75 years was no associated with an increased risk of graft loss (HR 1.95, 95%CI [0.65-5.82], P=0.23).

Conclusions

These results suggest that recipient age should not be considered itself as an absolute contraindication for kidney transplant.

Medical Aspects of mTOR Inhibition in Kidney Transplantation

The advances in transplant immunosuppression have reduced substantially the incidence of kidney graft rejection. In recent years, the focus has moved from preventing rejection to preventing the long-term consequences of long-standing immunosuppression, including nephrotoxicity induced by calcineurin inhibitors (CNI), as well as infectious and neoplastic complications. Since the appearance in the late 1990s of mTOR inhibitors (mTORi), these unmet needs in immunosuppression management could be addressed thanks to their benefits (reduced rate of viral infections and cancer). However, management of side effects can be troublesome and hands-on experience is needed. Here, we review all the available information about them. Thanks to all the basic, translational and clinical research achieved in the last twenty years, we now use mTORi as de novo immunosuppression in association with CNI. Another possibility is represented by the conversion of either CNI or mycophenolate (MPA) to an mTORi later on after transplantation in low-risk kidney transplant recipients.

Impact of insulin therapy before donation on graft outcomes in pancreas transplantation: An analysis of the OPTN/UNOS database

AIMS

Information on the impact of insulin therapy before pancreas donation on pancreas outcomes is scarce. We aim to explore the influence of insulin therapy before donation on recipient and pancreas graft survival.

METHODS

Registry study including 12,841 pancreas recipients from the OPTN/UNOS registry performed between 2000 and 2017. Inverse probability of treatment weighting (IPTW) was used to account for covariate imbalance between recipients from a donor with and without insulin requirements.

RESULTS

A total of 7765 (60%) patients received a pancreas from a donor with insulin before donation (IBD). Pancreas graft survival (death-censored) was similar between recipients from IBD and non-IBD donors at 1, 5 and 10 years (89% vs 89%, 78% vs 79 and 69% vs 70%, respectively, P = 0.35). Recipients from IBD donors presented a similar 90-days pancreas graft survival. After IPTW weighting, IBD donors were neither associated with any post-transplant surgical complication (HR 1.11 [95% CI 0.98-1.24], P = 0.06), nor with risk for recipient death (HR 0.94 [95% CI 0.85-1.04], P = 0.26), nor pancreas graft failure (HR 1.06 [95% CI 0.98-1.16], P = 0.15).

CONCLUSIONS

Insulin therapy before donation in accepted pancreas donors was not associated, per se, with an impaired pancreas graft and patient survival.

Cardiovascular calcifications in kidney transplant recipients

Vascular and valvular calcifications are highly prevalent in kidney transplant recipients and are associated with an increased risk of cardiovascular events, which represent the leading cause of long-term mortality in these patients. However, cardiovascular calcification has been traditionally considered as a condition mostly associated with advanced chronic kidney disease stages and dialysis, and comparatively fewer studies have assessed its impact after kidney transplantation. Despite partial or complete resolution of uremia-associated metabolic derangements, kidney transplant recipients are still exposed to several pro-calcifying stimuli that favour the progression of pre-existing vascular calcifications or their de novo development. Traditional risk factors, bone mineral disorders, inflammation, immunosuppressive drugs and deficiency of calcification inhibitors may all play a role, and strategies to correct or minimize their effects are urgently needed. The aim of this work is to provide an overview of established and putative mediators involved in the pathogenesis of cardiovascular calcification in kidney transplantation, and to describe the clinical and radiological features of these forms. We also discuss current evidence on preventive strategies to delay the progression of cardiovascular calcifications in kidney transplant recipients, as well as novel therapeutic candidates to potentially prevent their long-term deleterious effects.

Proper mTORC1 Activity Is Required for Glucose Sensing and Early Adaptation in Human Pancreatic β Cells

CONTEXT

The mechanistic target of rapamycin complex I (mTORC1) is crucial for β-cell identity and function in rodents. However, its possible relevance to the physiopathology of diabetes in humans remains unclear.

OBJECTIVE

This work aimed to understand the participation of mTORC1 in human β cells in prediabetes and diabetes.

DESIGN

We evaluated the PS6 immunofluorescence intensity in islets of pancreatic sections from 12 nondiabetic (ND), 11 impaired fasting glucose (IFG), and 11 glycemic-controlled type 2 diabetic (T2D) individuals. We also assessed the dynamic change of mTORC1 activity in β cells of db/db mice with new-onset diabetes.

RESULTS

There exists intercellular heterogeneity of mTORC1 activities in human islets. Islet mTORC1 activity was independently and positively correlated with FBG in ND, but not in IFG and T2D. Moreover, we did not detect significant change in mTORC1 activities between T2D and ND. Of note, the islet mTORC1 activities were significantly higher in IFG than in ND. We further stratified IFG individuals according to their islet PS6 levels and found that IFG-PS6high exhibited remarkably higher urocortin3 and glucose transporter 2 expression in their β cells compared to IFG-PS6low. Consistently, we also detected a significant increase in mTORC1 activities in prediabetic db/db mice compared to nondiabetic littermates. Interestingly, mTORC1 activities determined β-cell adaptation or failure in db/db mice: A strong negative correlation was found between islet mTORC1 activities and fasting glucose levels in db/db mice during their diabetes progression.

CONCLUSIONS

Our finding highlights a dynamic islet mTORC1 response in β-cell adaption/failure in human T2D.

The impact of functional delayed graft function in the modern era of kidney transplantation - A retrospective study

The dialysis-based definition of Delayed Graft Function (dDGF) is not necessarily objective as it depends on the individual physician's decision. The functional definition of DGF (fDGF, the failure of serum creatinine to decrease by at least 10% daily on 3 consecutive days during the first week post-transplant), may be more sensitive to reflect recovery after the ischemia-reperfusion injury. We retrospectively analyzed both definitions in 253 deceased donor kidney transplant recipients for predicting death-censored graft failure as primary outcome, using eGFR < 25 ml/min/1.73 m² as a surrogate end-point for graft failure. Secondary outcome was a composite outcome that included graft failure as above and also patient's death. Median follow-up was 3.22 [2.38-4.21] years. Seventy-nine patients developed dDGF (31.2%) and 127 developed fDGF (50.2%). Sixty-three patients fulfilled criteria for both definitions (24.9%). At multivariable analysis, the two definitions were significantly associated with the primary [HR (95%CI) 2.07 (1.09-3.94), P = 0.026 for fDGF and HR (95%CI) 2.41 (1.33-4.37), P = 0.004 for dDGF] and the secondary composite outcome [HR (95%CI) 1.58 (1.01-2.51), P = 0.047 for fDGF and HR (95%CI) 1.67 (1.05-2.66), P = 0.028 for dDGF]. Patients who met criteria for both definitions had the worst prognosis, with a three-year estimates (95%CI) of survival from the primary and secondary outcomes of 2.31 (2.02-2.59) and 2.20 (1.91-2.49) years for fDGF+/dDGF+, in comparison with the other groups (P < 0.01 for trend). fDGF provides supplementary information about graft outcomes on top of the dDGF definition in a modern series of kidney transplantation.

Modeling patients as decision making units: evaluating the efficiency of kidney transplantation through data envelopment analysis

The main applications of Data Envelopment Analysis (DEA) to medicine focus on evaluating the efficiency of different health structures, hospitals and departments within them. The evolution of patients after undergoing a medical procedure or their response to a given treatment are not generally studied through this programming technique. In addition to the difficulty inherent to the collection of this type of data, the use of a technique that is mainly applied to evaluate the efficiency of decision making units representing industrial and production structures to analyze the evolution of human patients may seem inappropriate. In the current paper, we illustrate how this is not actually the case and implement a decision engineering approach to model kidney transplantation patients as decision making units. As such, patients undergo three different phases, each composed by specific as well as interrelated variables, determining the potential success of the transplantation process. DEA is applied to a set of 12 input and 6 output variables - retrieved over a 10-year period - describing the evolution of 485 patients undergoing kidney transplantation from living donors. The resulting analysis allows us to classify the set of patients in terms of the efficiency of the transplantation process and identify the specific characteristics across which potential improvements could be defined on a per patient basis.

Everolimus for BKV nephropathy in kidney transplant recipients: a prospective, controlled study

There is no specific therapy for polyoma BK virus nephropathy (BKVN) in kidney transplant recipients, a condition associated with poor outcomes. Everolimus showed promising antiviral effects, but data from prospective studies are limited. Therefore, we converted ten consecutive kidney transplant recipients with biopsy-proven BKVN from standard exposure Calcineurin inhibitors and Mycophenolate to Everolimus and reduced exposure Calcineurin inhibitors. Ten patients not administered Everolimus, on reduced exposure Calcineurin inhibitor and halved MPA doses served as controls. All kidney transplant recipients continued steroid therapy. Each patient underwent kidney graft biopsy, BKV replication by PCR, and de novo DSA determination. During a 3-year follow-up no graft loss occurred in kidney transplant recipients on Everolimus but it was observed in 5/10 controls (P = 0.032). eGFR improved on Everolimus and worsened in controls (between group difference + 25.6 ml/min/1.73 m², 95% CI 10.5-40.7, P = 0.002). BKV replication declined in the Everolimus group alone (from 6.4 ± 0.8 to 3.6 ± 1.6 Log 10 genomic copies, P = 0.0001), and we found a significant inverse relationship between eGFR and BKV genomic copy changes (P = 0.022). Average Calcineurin inhibitors trough levels did not differ between the two study groups during follow-up. By multivariable Cox regression analysis, Everolimus treatment resulted the only significant predictor of survival free of a combined endpoint of graft loss and 57% eGFR reduction (P = 0.02). Kidney transplant recipients on Everolimus had a higher survival free of adverse graft outcome (log-rank test, P = 0.009). In conclusion an Everolimus-based immunosuppressive protocol with minimization of Calcineurin inhibitors and antimetabolite discontinuation effectively treated BKVN in kidney transplant recipients.