Association of Inflammation prior to Kidney Transplantation with Post-Transplant Diabetes Mellitus

Genetic and Epigenetic Associations with Post-Transplant Diabetes Mellitus

Post-transplant diabetes mellitus (PTDM) is a common complication of solid organ transplantation. PTDM prevalence varies due to different diabetes definitions. Consensus guidelines for the diagnosis of PTDM have been published based on random blood glucose levels, glycated hemoglobin (HbA1c), and oral glucose tolerance test (OGTT). The task of diagnosing PTDM continues to pose challenges, given the potential for diabetes to manifest at different time points after transplantation, thus demanding constant clinical vigilance and repeated testing. Interpreting HbA1c levels can be challenging after renal transplantation. Pre-transplant risk factors for PTDM include obesity, sedentary lifestyle, family history of diabetes, ethnicity (e.g., African-Caribbean or South Asian ancestry), and genetic risk factors. Risk factors for PTDM include immunosuppressive drugs, weight gain, hepatitis C, and cytomegalovirus infection. There is also emerging evidence that genetic and epigenetic variation in the organ transplant recipient may influence the risk of developing PTDM. This review outlines many known risk factors for PTDM and details some of the pathways, genetic variants, and epigenetic features associated with PTDM. Improved understanding of established and emerging risk factors may help identify people at risk of developing PTDM and may reduce the risk of developing PTDM or improve the management of this complication of organ transplantation.

Diabetes in Kidney Transplantation

Diabetes mellitus (DM) is one of the most common complications after kidney transplantation and is associated with unfavorable outcomes including death. DM can be present before transplant but post-transplant DM (PTDM) refers to diabetes that is diagnosed after solid organ transplantation. Despite its high prevalence, optimal treatment to prevent complications of PTDM is unknown. Medical therapy of pre-existent DM or PTDM after transplant is challenging because of frequent interactions between antidiabetic and immunosuppressive agents. There is also frequent need for medication dose adjustments due to residual kidney disease and a higher risk of medication side effects in patients treated with immunosuppressive agents. Sodium-glucose cotransporter 2 inhibitors have demonstrated a favorable cardio-renal profile in patients with DM without a transplant and hence hold great promise in this patient population although there is concern about the higher risk of urinary tract infections. The significant gaps in our understanding of the pathophysiology, diagnosis, and management of DM after kidney transplantation need to be urgently addressed.

Impact of transplantation on neutrophil extracellular trap formation in patients with end-stage renal disease: A single-center, prospective cohort study

ABSTRACT

Increased neutrophil extracellular trap (NET) formation associates with high cardiovascular risk and mortality in patients with end-stage renal disease (ESRD). However, the effect of transplantation on NETs and its associated markers remains unclear. This study aimed to characterize circulating citrullinated Histone H3 (H3cit) and Peptidyl Arginase Deiminase 4 (PAD4) in ESRD patients undergoing transplantation and evaluate the ability of their neutrophils to release NETs.This prospective cohort study included 80 healthy donors and 105 ESRD patients, out of which 95 received a transplant. H3cit and PAD4 circulating concentration was determined by enzyme-linked immunosorbent assay in healthy donors and ESRD patients at the time of enrollment. An additional measurement was carried out within the first 6 months after transplant surgery. In vitro NET formation assays were performed in neutrophils isolated from healthy donors, ESRD patients, and transplant recipients.H3cit and PAD4 levels were significantly higher in ESRD patients (H3cit, 14.38 ng/mL [5.78-27.13]; PAD4, 3.22 ng/mL [1.21-6.82]) than healthy donors (H3cit, 6.45 ng/mL [3.30-11.65], P < .0001; PAD4, 2.0 ng/mL [0.90-3.18], P = .0076). H3cit, but not PAD4, increased after transplantation, with 44.2% of post-transplant patients exhibiting high levels (≥ 27.1 ng/mL). In contrast, NET release triggered by phorbol 12-myristate 13-acetate was higher in neutrophils from ESRD patients (70.0% [52.7-94.6]) than healthy donors (32.2% [24.9-54.9], P < .001) and transplant recipients (19.5% [3.5-65.7], P < .05).The restoration of renal function due to transplantation could not reduce circulating levels of H3cit and PAD4 in ESRD patients. Furthermore, circulating H3cit levels were significantly increased after transplantation. Neutrophils from transplant recipients exhibit a reduced ability to form NETs.

The relationship between periodontal status and hyperglycemia after kidney transplantation

OBJECTIVES

Several factors have been associated with hyperglycemia after kidney transplantation (KTx), including systemic inflammation. This study aimed to investigate the relationship between periodontal status and hyperglycemia in KTx patients.

MATERIALS AND METHODS

Forty-four KTx patients were included in this cross-sectional study. Periodontitis severity was categorized into stage I to IV. Fasting blood glucose (FBG) was measured, and hyperglycemia was analyzed at different FBG cutoff points (100 mg/dL, 110 mg/dL, 120 mg/dL, 126 mg/dL, 140 mg/dL). Age, history of smoking, prior type 2 diabetes (T2D), and prior cardiovascular disease (CVD) were considered cofounders. Multivariable logistic regression modelling was performed with periodontitis as the exposure and hyperglycemia as the outcome. Pathway analysis was performed with FBG as a continuous outcome.

RESULTS

Periodontitis had increased odds of hyperglycemia from 120 mg/dL FBG cutoff, even after adjustment. In addition, periodontitis severity was positively associated with FBG level (β = 0.323, SE = 0.127, P = 0.011).

CONCLUSION

The findings suggest that periodontitis may be related to increase of hyperglycemia and FBG levels in KTx patients.

CLINICAL RELEVANCE

Periodontitis severity and cardiovascular disease were positively associated with FBG levels in KTx patients. Clinicians and patients should be aware of the potential benefit of periodontal care for better glycemic control management.

Post-transplant diabetes mellitus in patients with solid organ transplants

Solid organ transplantation (SOT) is a life-saving procedure and an established treatment for patients with end-stage organ failure. However, transplantation is also accompanied by associated cardiovascular risk factors, of which post-transplant diabetes mellitus (PTDM) is one of the most important. PTDM develops in 10-20% of patients with kidney transplants and in 20-40% of patients who have undergone other SOT. PTDM increases mortality, which is best documented in patients who have received kidney and heart transplants. PTDM results from predisposing factors (similar to type 2 diabetes mellitus) but also as a result of specific post-transplant risk factors. Although PTDM has many characteristics in common with type 2 diabetes mellitus, the prevention and treatment of the two disorders are often different. Over the past 20 years, the lifespan of patients who have undergone SOT has increased, and PTDM becomes more common over the lifespan of these patients. Accordingly, PTDM becomes an important condition not only to be aware of but also to treat. This Review presents the current knowledge on PTDM in patients receiving kidney, heart, liver and lung transplants. This information is not only for transplant health providers but also for endocrinologists and others who will meet these patients in their clinics.

Inflammatory and related biomarkers are associated with post-transplant diabetes mellitus in kidney recipients: a retrospective study

In this study, we investigate the association between selected inflammatory-related biomarkers and post-transplant hyperglycemia in kidney transplant recipients. This retrospective analysis comprises 852 patients receiving a kidney transplant at the Norwegian national transplant center between 2007 and 2012, all having a normal oral glucose tolerance test (OGTT) before transplantation. A diagnostic OGTT was performed 10 weeks post-transplant to examine the association between inflammation-related biomarkers and two-hour plasma glucose (2HPG) by multivariable linear regression models adjusting for BMI, age, graft function, fasting insulin levels, dosage of prednisolone, and concentration of calcineurin inhibitors. Six of 20 biomarkers were significantly associated with 2HPG in multivariate analyses showing strong associations with soluble tumor necrosis factor type 1 (P = 0.027), Pentraxin 3 (P = 0.019), macrophage migration inhibitory factor (P = 0.024), and endothelial protein C receptor (P = 0.001). These associated markers reflect several distinct but also overlapping pathways including activation of tumor necrosis factor, macrophages, and endothelial cells. The multinomial logistic regression model showed a clear association between the inflammatory biomarkers and post-transplant diabetes mellitus (PTDM). The association between a range of inflammation markers and PTDM suggests that these markers may be target for future studies on pathogenesis and perhaps also treatment of PTDM.

Uremia induces adipose tissue inflammation and muscle mitochondrial dysfunction

Background.

End-stage renal disease (ESRD) is associated with inflammation and increased reactive oxygen species (ROS). Inflammation and oxidative stress are associated with several complications of ESRD. The aim of this study was to determine histological characteristics of adipose tissue and muscle mitochondrial function in uremia and its relationship with inflammation.

Methods.

ESRD patients ( n  = 18) and controls ( n  = 6) were enrolled for studies of adipose and muscle tissue by immunohistochemistry and western blot. In a uremic muscle cell model, C2C12 cells were exposed to uremic serum and inflammatory cytokines. Mitochondrial function was studied by MitoTracker Orange, translocase of the mitochondrial outer membrane 20 (TOMM20) and mitochondrial oxidative phosphorylation complex subunit expression.

Results.

ESRD patients had increased macrophage infiltration in subcutaneous and visceral adipose tissue compared with controls, even in nonobese ESRD patients (P < 0.05). Compared with controls, TOMM20 expression in muscle tissue was lower in ESRD, consistent with reduced mitochondrial function (P < 0.05). C2C12 exposed to uremia had decreased mitotracker intensity (P < 0.05) and the reduced mitochondrial function was rescued by N-acetyl cysteine (P < 0.01). Similarly, C2C12 cells exposed to tumor necrosis factor α (TNF-α)/interleukin-6 (IL-6) have decreased mitotracker intensity (P < 0.01) that was rescued with adiponectin (P < 0.05). C2C12 exposed to TNF-α, IL-6 and buthionine sulfoximine had decreased TOMM20 expression and cells exposed to TNF-α showed a decrease in subunits of mitochondrial complexes I and III.

Conclusion.

Our data indicate that uremia is associated with increased adipose tissue macrophage infiltration and concurrent muscle tissue mitochondrial dysfunction induced by inflammation/ROS. Adipose tissue is a potential source of inflammation in ESRD that is not due to increased adiposity and may contribute to mitochondrial dysfunction in uremia.