Use of Mammalian Target of Rapamycin Inhibitors for Pancreas Transplant Immunosuppression Is Associated With Improved Allograft Survival and Improved Early Patient Survival

A comprehensive update of the metabolic and toxicological considerations for immunosuppressive drugs used during pancreas transplantation

INTRODUCTION

Despite significant advancements in immunosuppressive regimens and surgical techniques, the prevalence of adverse events related to immunosuppression remains a major challenge affecting the long-term survival rates of pancreas and kidney allografts.

AREAS COVERED

This article presents a comprehensive review of the literature and knowledge (Jan/2012-Feb/2023) concerning glucose metabolism disorders and nephrotoxicity associated with tacrolimus and mammalian target of rapamycin inhibitors (mTORi). Novel signaling pathways potentially implicated in these adverse events are discussed. Furthermore, we extensively examine the findings from clinical trials evaluating the efficacy and safety of tacrolimus, mTORi, and steroid minimization.

EXPERT OPINION

Tacrolimus-based regimens continue to be the standard treatment following pancreas transplants. However, prolonged use of tacrolimus and mTORi may lead to hyperglycemia and nephrotoxicity. Understanding and interpreting experimental data, particularly concerning novel signaling pathways beyond calcineurin-NFAT and mTOR pathways, can offer valuable insights for therapeutic interventions to mitigate hyperglycemia and nephrotoxicity. Additionally, critically analyzing clinical trial results can identify opportunities for personalized safety-based approaches to minimize side effects. It is imperative to conduct randomized-controlled studies to assess the impact of mTORi use and steroid-free protocols on pancreatic allograft survival. Such studies will aid in tailoring treatment strategies for improved transplant outcomes.

First World Consensus Conference on pancreas transplantation: Part II - recommendations

The First World Consensus Conference on Pancreas Transplantation provided 49 jury deliberations regarding the impact of pancreas transplantation on the treatment of diabetic patients, and 110 experts' recommendations for the practice of pancreas transplantation. The main message from this consensus conference is that both simultaneous pancreas-kidney transplantation (SPK) and pancreas transplantation alone can improve long-term patient survival, and all types of pancreas transplantation dramatically improve the quality of life of recipients. Pancreas transplantation may also improve the course of chronic complications of diabetes, depending on their severity. Therefore, the advantages of pancreas transplantation appear to clearly surpass potential disadvantages. Pancreas after kidney transplantation increases the risk of mortality only in the early period after transplantation, but is associated with improved life expectancy thereafter. Additionally, preemptive SPK, when compared to SPK performed in patients undergoing dialysis, appears to be associated with improved outcomes. Time on dialysis has negative prognostic implications in SPK recipients. Increased long-term survival, improvement in the course of diabetic complications, and amelioration of quality of life justify preferential allocation of kidney grafts to SPK recipients. Audience discussions and live voting are available online at the following URL address: http://mediaeventi.unipi.it/category/1st-world-consensus-conference-of-pancreas-transplantation/246.

Pharmacoproteomics reveals the mechanism of Chinese dragon's blood in regulating the RSK/TSC2/mTOR/ribosome pathway in alleviation of DSS-induced acute ulcerative colitis

ETHNOPHARMACOLOGICAL RELEVANCE

Chinese dragon's blood (CDB), a crude drug extracted from Dracaena cochinchinensis (Lour.) S.C. Chen, has been historically applied for the treatment of various diseases, including ulcerative colitis (UC). Unfortunately, the underlying molecular mechanism remains unclear.

MATERIALS AND METHODS

In this paper, the effects of CDB treatment on a mouse model of acute UC and proteomic variation in colonic tissue were investigated. The acute UC model in Balb/c mice was induced by administration of 2.5% (wt/vol) dextran sulfate sodium (DSS) in drinking water for 8 days. After the mice with UC were intragastrically administered CDB and intraperitoneally injected with rapamycin (RAPA, a specific inhibitor of mTORC1), the disease activity index (DAI) and histopathological score were recorded. An isobaric tags for relative and absolute quantification (iTRAQ) based LC-MS/MS proteomic technique was adopted to identify the differentially expressed proteins (DEPs) in colonic tissue. Bioinformatics analysis was used to discover the molecular functions and pathways of the DEPs. Finally, Western blot analysis and immunohistochemistry were used to verify the protein expression.

RESULTS

The results showed that CDB treatment significantly ameliorated the symptoms and intestinal damage in acute UC, while RAPA treatment led to severe symptoms and intestinal damage. A total of 489 DEPs were reversed in the control check (CK) group and the CDB group. Most DEPs were enriched in the structural constituents of ribosomes and the ribosome pathway. CDB treatment significantly upregulated the expression of the mTOR, p-mTOR and p70S6K proteins and downregulated the expression of the Akt, p-Akt, and p4EBP1 proteins. However, RAPA treatment, unlike CDB, did not return the levels of mTOR, Akt, and their phosphorylated forms to nearly normal.

CONCLUSIONS

In conclusion, the dysfunction of the mTOR/ribosome pathway resulting in the inhibition of ribosome synthesis played an important role in the development of acute UC in mice, and CDB, but not RAPA, was an alternative drug for the treatment of acute UC by enhancing ribosome synthesis via the mTOR/ribosome pathway and further promoting protein synthesis.

Late Conversion to Sirolimus or Everolimus After Pancreas Transplant

BACKGROUND

Pancreas transplant is an effective treatment for insulin-dependent diabetic individuals with end-stage renal disease, yet immunosuppression-associated adverse events may adversely affect patient and graft survival. The aim of the study was to document whether mammalian target of rapamycin inhibitors (mTORi) are safe and effective as a second-line drug after pancreas transplant.

METHODOLOGY

An observational single-center study was performed in a cohort of 490 simultaneous pancreas-kidney transplant and 45 pancreas-after-kidney transplant individuals after conversion to mTORi (n = 13) owing to adverse events of either tacrolimus or mycophenolate.

RESULTS

mTORi conversion was performed 11.5 ± 10.1 (range, 1-28) months after pancreas transplant, mainly owing to cytomegalovirus infection and gastrointestinal intolerance. We frequently observed clinical complications after mTORi conversion, yet creatinine, eGFR, proteinuria, fasting plasma glucose, HbA1c, and C-peptide remained stable throughout the study (mean follow-up 8.2 ± 5, range 1-17) years, as did the lipid profile (P > .05). However, graft loss occurred in almost 20% of patients owing to chronic alterations.

LIMITATIONS

The small number of patients and a single-center cohort were limitations of the study.

CONCLUSIONS

Late mTORi conversion is a safe and effective approach when tacrolimus or mycophenolate-mediated adverse events occur after pancreas transplant.