Renal transplant immunosuppression impairs natural killer cell function in vitro and in vivo. PLoS One. 2010;5:e13294. [PMID: 20967261 PMCID: PMC2953494 DOI: 10.1371/journal.pone.0013294]

The value and complexity of studying cellular immunity against BK Polyomavirus in kidney transplant recipients

BK Polyomavirus is of particular concern for kidney transplant recipients, due to their immunosuppression. This problem is exacerbated by the high effectiveness of antirejection therapies, which also compromise the organism's ability to fight viral infections. The long-term risk is loss of graft function through BKPyV-associated nephropathy (BKPyVAN). The assessment of host immunity and its link to the control of viral infections is a major challenge. In terms of humoral immunity, researchers have highlighted the prognostic value of the pre-transplantation anti-BKPyV immunoglobulin G titer. However, humoral immunity alone does not guarantee viral clearance, and the correlation between the humoral response and the time course of the infection remains weak. In contrast, cellular immunity variables appear to be more closely associated with viral clearance, given that the cellular immune response to the kidney transplant is the main target of immunosuppressive treatments in recipients. However, the assessment of the cellular immune response to BK Polyomavirus is complex, and many details still need to be characterized. Here, we review the current state of knowledge about BKPyV cellular immunity, as well as the difficulties that may be encountered in studying it in kidney transplant recipient. This is an essential area of research for optimizing the management of transplant recipients and minimizing the risks associated with insidious BKPyV disease.

Incidence of De Novo Post-Transplant Malignancies in Thai Adult Kidney Transplant Recipients: A Single-Center, Population-Controlled, Retrospective Cohort Study at the Highest Volume Kidney Transplant Center in Thailand

Kidney transplant recipients (KTRs) are at increased risk of developing de novo post-transplant malignancies (PTMs), with regional differences in types with excess risk compared to the general population. A single-center, population-controlled, retrospective cohort study was conducted at a tertiary care center in Thailand among all adults who underwent their first kidney transplant from 1986 to 2018. Standardized incidence ratios (SIRs) of malignancy by age, sex, and place of residence were obtained using data from the National Cancer Registry of Thailand as population control. There were 2,024 KTRs [mean age, 42.4 years (SD 11.4); female patients, 38.6%] during 16,495 person-years at risk. Of these, 125 patients (6.2%) developed 133 de novo PTMs. The SIR for all PTMs was 3.85 (95% CI 3.22, 4.56), and for pooled solid and hematologic PTMs, it was 3.32 (95% CI 2.73, 3.99). Urothelial malignancies had the largest excess risk, especially in women [female SIR 114.7 (95% CI 66.8, 183.6); male SIR 17.5 (95% CI 8.72, 31.2)]. The next two most common cancers were non-Hodgkin's lymphoma and skin cancer [SIR 20.3 (95% CI 13.6, 29.1) and 24.7 (95% CI 15.3-37.8), respectively]. Future studies are needed to identify the risk factors and assess the need for systematic screening among PTMs with excess risk in KTRs.

Cellular Immunobiology and Molecular Mechanisms in Alloimmunity-Pathways of Immunosuppression

Current maintenance immunosuppression commonly comprises a synergistic combination of tacrolimus as calcineurin inhibitor (CNI), mycophenolic acid, and glucocorticoids. Therapy is often individualized by steroid withdrawal or addition of belatacept or inhibitors of the mechanistic target of rapamycin. This review provides a comprehensive overview of their mode of action, focusing on the cellular immune system. The main pharmacological action of CNIs is suppression of the interleukin-2 pathway that leads to inhibition of T cell activation. Mycophenolic acid inhibits the purine pathway and subsequently diminishes T and B cell proliferation but also exerts a variety of effects on almost all immune cells, including inhibition of plasma cell activity. Glucocorticoids exert complex regulation via genomic and nongenomic mechanisms, acting mainly by downregulating proinflammatory cytokine signatures and cell signaling. Belatacept is potent in inhibiting B/T cell interaction, preventing formation of antibodies; however, it lacks the potency of CNIs in preventing T cell-mediated rejections. Mechanistic target of rapamycin inhibitors have strong antiproliferative activity on all cell types interfering with multiple metabolic pathways, partly explaining poor tolerability, whereas their superior effector T cell function might explain their benefits in the case of viral infections. Over the past decades, clinical and experimental studies provided a good overview on the underlying mechanisms of immunosuppressants. However, more data are needed to delineate the interaction between innate and adaptive immunity to better achieve tolerance and control of rejection. A better and more comprehensive understanding of the mechanistic reasons for failure of immunosuppressants, including individual risk/benefit assessments, may permit improved patient stratification.

Investigating the relationship between the number and activity of natural killer cells with increased cytomegalovirus and CMV disease after kidney transplantation

BACKGROUND

Cytomegalovirus (CMV) infections caused by the cytomegalovirus are one of the most common problems in patients after kidney transplant. We examined the association of the relationship between the number and activity of natural killer cells with increased cytomegalovirus and its related disease after kidney transplantation.

MATERIAL AND METHODS

In this analytical study, 58 new transplant patients in the Labbafinejad Hospital, who did not have any evidence of CMV infection, were evaluated based on the number and percentage of CD56+/16+, CD56+/16-, and CD69+ Natural Killer (NK) cells.

RESULTS

The results of this study showed that CD16+ and CD56+ cells in the group of CMV Ag-positive patients are less than negative patients (p = 0.003) and the difference between the two groups are significant (p = 0.01). However, CD69+ cells did not differ significantly between the two groups (p = 0.1). Moreover, the absolute number of CD16+ and CD56+ cells declined significantly after infection with CMV unlike the CMV Ag - group(p = 0.003).

DISCUSSION

These results indicate that kidney transplant patients suffering from CMV infection after transplantation have a significantly reduced total number of NK cells. On the other hand, a slight decrease in the number of NK subgroups was observed with an increase in the peak serum levels of cyclosporine. As a consequence of these findings, it can be assumed that more dosage and a higher level of the drug will result in more severe immunosuppression and, consequently, increased susceptibility to CMV infections. Thus, taking the right dose of the drug would prevent viral infections and immune system from over-activation.

Immature and activated phenotype of blood NK cells is associated with acute rejection in adult liver transplant

Natural killer (NK) cells contribute to liver transplant (LTx) rejection. However, the blood-circulating NK-cell dynamics of patients who experience acute rejection (AR) are unclear. Herein, we longitudinally profiled the total NK cells and their subsets, along with the expression of activating and inhibitory receptors in sequential peripheral blood mononuclear cell samples, spanning from before LTx to the first year after LTx of 32 patients with AR and 30 patients under a steady immune status. Before transplantation, patients with AR (rejectors) contained a significantly higher proportion of the immature CD56 bright CD16 - subset and a lower cytolytic CD56 dim CD16 + in the total blood-circulating NK cells than patients with steady immunity. Both subsets contained a high NKp30-positive population, and CD56 dim CD16 + additionally exhibited a high NKp46-positive ratio. The NKp30-positive ratio in CD56 dim CD16 + subset showed the most prominent AR predictive ability before LTx and was an independent risk factor of LTx AR. After transplantation, the blood-circulating NK cells in rejectors maintained a higher CD56 bright CD16 - and lower CD56 dim CD16 + composition than the controls throughout the first year after LTx. Moreover, both subsets maintained a high NKp30-positive ratio, and CD56 dim CD16 + retained a high NKp46-positive ratio. The blood-circulating NK cell subset composition was consistent during AR, while the expressions of NKp30 and NKp46 were augmented. Collectively, a more immature CD56 bright CD16 - subset composition and an activated phenotype of high NKp30 expression were the general properties of blood-circulating NK cells in rejected LTx recipients, and the NKp30-positive ratio in CD56 dim CD16 + NK subset before LTx possessed AR predictive potential.

Dectin-1/IL-15 Pathway Affords Protection against Extrapulmonary Aspergillus fumigatus Infection by Regulating Natural Killer Cell Survival

Aspergillus fumigatus is a ubiquitous, yet potentially pathogenic, mold. The immune system employs innate receptors, such as dectin-1, to recognize fungal pathogens, but the immunological networks that afford protection are poorly explored. Here, we investigated the role of dectin-1 in anti-A. fumigatus response in an experimental model of acute invasive aspergillosis. Mice lacking dectin-1 presented enhanced signs of inflammation, with increased production of inflammatory cytokines and neutrophil infiltration, quickly succumbing to the infection. Curiously, resistance did not require T/B lymphocytes or IL-17. Instead, the main effector function of dectin-1 was the preservation of the NK cell population in the kidneys by the provision of the cytokine IL-15. While the depletion of NK cells impaired host defense in wild-type mice, IL-15 administration restored antifungal responses in dectin-1-deficient mice. Our results uncover a new effector mechanism for dectin-1 in anti-Aspergillus defense, adding an alternative approach to understand the pathophysiology of this infection.

Scope and Consistency of Cancer Outcomes Reported in Randomized Trials in Kidney Transplant Recipients

Introduction

Cancer is an important outcome in kidney transplantation, but the scope and consistency of how cancer is defined and reported in trials involving kidney transplant recipients has not been evaluated. This study aimed to assess the range and variability of cancer outcomes in trials involving kidney transplant recipients.

Methods

The ClinicalTrials.gov database was searched from February 2000 to July 2021 to identify all randomized controlled trials (RCTs) in adult kidney transplant recipients, and which included cancer as a specified outcome. The definition of cancer, types of cancer (if any), timepoint(s) of measurement and method of aggregation were extracted for each cancer outcome.

Results

Of the 819 trials in kidney transplantation, only 84 (10%) included 1 or more cancer outcomes. Of these, 72 of 84 (86%) trials included cancer as a secondary outcome and 12 of 84 (14%) considered cancer as a primary outcome. The most frequent description of cancer was "malignancy" (n = 44, 43%), without reference to diagnostic criteria, histology, grade, or stage. The 2 most common cancer types were posttransplant lymphoproliferative disorder (PTLD) (n = 20, 20%) and nonmelanoma skin cancer (n = 10, 10%). Several methods of aggregation were identified, including incidence or rate (n = 47, 46%), frequency or proportion (n = 30, 29%), and time to event (n = 5, 5%). Approximately half the cancer outcomes were measured at a single time point (n = 44, 52%).

Conclusion

Cancer is an infrequently reported outcome and is inconsistently defined in trials of kidney transplant recipients. Consistent reporting of cancer outcomes using standardized definitions would provide important information on the impact of cancer in patients after kidney transplantation.

The Role of the Oral Immune System in Oropharyngeal Candidiasis-Facilitated Invasion and Dissemination of Staphylococcus aureus

Candida albicans and Staphylococcus aureus account for most invasive fungal and bacterial bloodstream infections (BSIs), respectively. However, the initial point of invasion responsible for S. aureus BSIs is often unclear. Recently, C. albicans has been proposed to mediate S. aureus invasion of immunocompromised hosts during co-colonization of oral mucosal surfaces. The status of the oral immune system crucially contributes to this process in two distinct ways: firstly, by allowing invasive C. albicans growth during dysfunction of extra-epithelial immunity, and secondly following invasion by some remaining function of intra-epithelial immunity. Immunocompromised individuals at risk of developing invasive oral C. albicans infections could, therefore, also be at risk of contracting concordant S. aureus BSIs. Considering the crucial contribution of both oral immune function and dysfunction, the aim of this review is to provide an overview of relevant aspects of intra and extra-epithelial oral immunity and discuss predominant immune deficiencies expected to facilitate C. albicans induced S. aureus BSIs.

Efficacy of tacrolimus as long-term immunotherapy for neuronal surface antibody-mediated autoimmune encephalitis

Aims:

We aimed to verify the efficacy and safety of tacrolimus as long-term immunotherapy for the treatment of neuronal surface antibody-mediated autoimmune encephalitis (AE) during the first attack.

Methods:

In this retrospective observational cohort study, patients with neuronal surface antibody-mediated AE who experienced the first attack were enrolled. We compared the outcomes of 17 patients who received tacrolimus with those of 47 patients treated without tacrolimus. Patients were assessed at onset and 3, 6, and 12 months, as well as at the last follow-up, by using the modified Rankin scale (mRS) and the Clinical Assessment Scale in Autoimmune Encephalitis (CASE). The efficacy of tacrolimus was also compared in a subgroup of patients with anti-NMDA receptor encephalitis.

Results:

Among all patients with neuronal surface antibody-mediated AE, those receiving tacrolimus had lower median mRS scores [1 (IQR = 0–1) versus 2 (IQR = 1–3) in controls, p = 0.001)], CASE scores [2 (IQR = 1–3) versus 3 (IQR = 2–7), p = 0.006], and more favorable mRS scores (94.1% versus 68.1%, p = 0.03) at the 3-month follow-up. No difference was found at the last follow-up. There was no significant difference in the occurrence of relapse and adverse events between the two groups (11.8% versus 14.9%, p = 0.75). In the subgroup of patients with anti-NMDA receptor encephalitis, patients treated with tacrolimus had a lower median mRS score at the 3-month follow-up [1 (IQR = 0–2) versus 2 (IQR = 1–3), p = 0.03]; however, no difference in the outcome was detected at the last follow-up.

Conclusion:

Tacrolimus can be used as long-term immunotherapy in patients with neuronal surface antibody-mediated AE during the first attack. Treatment with tacrolimus appears to accelerate the clinical improvement of neuronal surface antibody-mediated AE.

COVID-19 Disease and Dermatomyositis: A Mini-Review

The pandemic of coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 has caused a large number of deaths, and there is still no effective treatment. COVID-19 can induce a systemic inflammatory response, and its clinical manifestations are diverse. Recently, it has been reported that COVID-19 patients may develop myositis and interstitial pulmonary disease similar to dermatomyositis (DM). This condition is similar to the rapidly progressive interstitial lung disease associated with MDA5+ DM that has a poor prognosis and high mortality, and this poses a challenge for an early identification. Suppression of the immune system can protect COVID-19 patients by preventing the production of inflammatory cytokines. This article attempts to explore the possibility of a relationship between COVID-19 and DM in terms of the potential pathogenesis and clinical features and to analyze the therapeutic effect of the immunosuppressive drugs that are commonly used for the treatment of both DM and COVID-19.

Immune-checkpoint inhibitors in renal transplanted patients affected by melanoma: a systematic review

Kidney transplantation leads to an increased risk of cancer. Melanoma is one of the most frequent neoplasms in kidney transplant recipients. Transplanted patients were excluded from trials with checkpoint inhibitors in melanoma. The authors performed a systematic review regarding the use of anti-PD1 and anti-CTLA4 agents in renal transplanted patients with melanoma. Thirty-four cases were included (24 progressive disease, eight partial responses and one stable disease) but no complete response were reported. Fourteen graft rejections were observed, especially with anti-PD1 agent. The median time from the start of immune-checkpoint inhibitor and rejection was 21 days. Response rate was similar between patients with rejection and patients without rejection. The benefit of immune-checkpoint inhibitors versus the risk of allograft rejection should be carefully weighted for each patient. A multidisciplinary approach should be considered to discuss the most appropriate treatment for every case, given the aggressiveness of melanoma in these subsets of patients.

Missing Self-Induced Microvascular Rejection of Kidney Allografts: A Population-Based Study

BACKGROUND

Circulating anti-HLA donor-specific antibodies (HLA-DSA) are often absent in kidney transplant recipients with microvascular inflammation (MVI). Missing self, the inability of donor endothelial cells to provide HLA I-mediated signals to inhibitory killer cell Ig-like receptors (KIRs) on recipient natural killer cells, can cause endothelial damage in vitro, and has been associated with HLA-DSA-negative MVI. However, missing self's clinical importance as a nonhumoral trigger of allograft rejection remains unclear.

METHODS

In a population-based study of 924 consecutive kidney transplantations between March 2004 and February 2013, we performed high-resolution donor and recipient HLA typing and recipient KIR genotyping. Missing self was defined as the absence of A3/A11, Bw4, C1, or C2 donor genotype, with the presence of the corresponding educated recipient inhibitory KIR gene.

RESULTS

We identified missing self in 399 of 924 transplantations. Co-occurrence of missing self types had an additive effect in increasing MVI risk, with a threshold at two concurrent types (hazard ratio [HR], 1.78; 95% confidence interval [95% CI], 1.26 to 2.53), independent of HLA-DSA (HR, 5.65; 95% CI, 4.01 to 7.96). Missing self and lesions of cellular rejection were not associated. No HLA-DSAs were detectable in 146 of 222 recipients with MVI; 28 of the 146 had at least two missing self types. Missing self associated with transplant glomerulopathy after MVI (HR, 2.51; 95% CI, 1.12 to 5.62), although allograft survival was better than with HLA-DSA-associated MVI.

CONCLUSION

Missing self specifically and cumulatively increases MVI risk after kidney transplantation, independent of HLA-DSA. Systematic evaluation of missing self improves understanding of HLA-DSA-negative MVI and might be relevant for improved diagnostic classification and patient risk stratification.

HLA Class I Molecules as Immune Checkpoints for NK Cell Alloreactivity and Anti-Viral Immunity in Kidney Transplantation

Natural killer (NK) cells are innate lymphocytes that can kill diseased- or virally-infected cells, mediate antibody dependent cytotoxicity and produce type I immune-associated cytokines upon activation. NK cells also contribute to the allo-immune response upon kidney transplantation either by promoting allograft rejection through lysis of cells of the transplanted organ or by promoting alloreactive T cells. In addition, they protect against viral infections upon transplantation which may be especially relevant in patients receiving high dose immune suppression. NK cell activation is tightly regulated through the integrated balance of signaling via inhibitory- and activating receptors. HLA class I molecules are critical regulators of NK cell activation through the interaction with inhibitory- as well as activating NK cell receptors, hence, HLA molecules act as critical immune checkpoints for NK cells. In the current review, we evaluate how NK cell alloreactivity and anti-viral immunity are regulated by NK cell receptors belonging to the KIR family and interacting with classical HLA class I molecules, or by NKG2A/C and LILRB1/KIR2DL4 engaging non-classical HLA-E or -G. In addition, we provide an overview of the methods to determine genetic variation in these receptors and their HLA ligands.

De Novo Carcinoma after Solid Organ Transplantation to Give Insight into Carcinogenesis in General-A Systematic Review and Meta-Analysis

Simple Summary

Patients receiving a solid organ transplantation, such as a kidney, liver, or lung transplantation, inevitably have to take drugs to suppress the immune system in order to prevent rejection of the transplanted organ. However, these drugs are known to cause malignancies in the long term. This study focuses specifically on newly developed carcinomas in patients who use those drugs after a solid organ transplantation. This systematic review and meta-analysis of published data show a 20-fold risk to develop a carcinoma after solid organ transplantation compared to the general population, with specifically increased risks in patients who receive cyclosporine or azathioprine. By comparing the different pathways involved in immunosuppression and the occurrence of carcinoma development, new insights can be discovered for future research and understanding of carcinoma development in transplantation patients and the general population as well.

Abstract

Immunosuppressive therapy after solid organ transplantation leads to the development of cancer in many recipients. Analysis of the occurrence of different types of de novo carcinomas in relation to specific immunosuppressive drugs may give insight into their carcinogenic process and carcinogenesis in general. Therefore, a systematic search was performed in Embase and PubMed. Studies describing over five de novo carcinomas in patients using immunosuppressive drugs after solid organ transplantation were included. Incidence per 1000 person-years was calculated with DerSimonian–Laird random effects model and odds ratio for developing carcinomas with the Mantel–Haenszel test. Following review of 5606 papers by title and abstract, a meta-analysis was conducted of 82 studies. The incidence rate of de novo carcinomas was 8.41. Patients receiving cyclosporine developed more de novo carcinomas compared to tacrolimus (OR1.56, 95%CI 1.00–2.44) and mycophenolate (OR1.26, 95%CI 1.03–1.56). Patients receiving azathioprine had higher odds to develop de novo carcinomas compared to mycophenolate (OR3.34, 95%CI 1.29–8.65) and head and neck carcinoma compared to tacrolimus (OR3.78, 95%CI 1.11–12.83). To conclude, patients receiving immunosuppressive drugs after solid organ transplantation have almost a 20-fold increased likelihood of developing carcinomas, with the highest likelihood for patients receiving cyclosporine A and azathioprine. Looking into altered immune pathways affected by immunosuppressive drugs might lead to better understanding of carcinogenesis in general.

Dysfunction of natural killer cells in end-stage kidney disease on hemodialysis

Natural killer (NK) cells are known to play an important role in defense against infection and tumors. Although there is no clear consensus, most studies have shown that the number and cytotoxicity of NK cells decreases in end-stage kidney disease (ESKD) patients undergoing hemodialysis. Uremic patients chronically suffer from oxidative stress, which could be responsible for downregulation of the activating receptors on NK cells and modulation of ligand expression for activating receptors. Theoretically, the reduced number of NK cells and decreased function might increase susceptibility to viral infections and cancer development in patients with ESKD. There is emerging evidence that NK cell numbers may be an outcome predictor in renal transplantation; however, the clinical significance of NK cell dysfunction in dialysis patients requires clarification. In this review, I describe NK cell number, cytotoxic activity, and activating mechanisms in the context of uremia and oxidative stress, which is anticipated to assist in elucidating the mechanisms underlying immunodeficiency in dialysis patients.

Iacta Alea Est: The Inexorable Advance of Tofacitinib in the Treatment of Dermatomyositis-Associated Rapidly Progressive Interstitial Lung Disease. A Case Report

Rapidly progressive interstitial lung disease is typically associated with clinically amyopathic dermatomyositis and the anti-melanoma differentiation associated gene 5 antibody, a condition with high mortality and resistance to classic immunosuppression. Recent reports have described the efficacy of the Janus kinase inhibitor tofacitinib in the treatment of rapidly progressive interstitial lung disease in anti-melanoma differentiation associated gene 5 antibody-positive clinically amyopathic dermatomyositis. It is uncertain, however, whether tofacitinib alters the course of rapidly progressive interstitial lung disease in other variants of dermatomyositis that are unrelated to the anti-melanoma differentiation associated gene 5 antibody and whether the early addition of the anti-fibrotic tyrosine kinase inhibitor nintedanib interferes with the development of fibrosis. To answer these questions, we present and discuss the case of an elderly woman who presented with a flare of dermatomyositis sine myositis. Based upon the detection of anti-Jo-1 antibodies and the absence of anti-melanoma differentiation associated gene 5 antibodies, anti-synthetase syndrome was diagnosed. While the cutaneous manifestations quickly resolved with prednisone, azathioprine and tacrolimus, the respiratory function paradoxically and rapidly deteriorated, and invoked the use of tofacitinib. Markedly raised ferritin levels and a severe numerical deficiency of circulating natural killer cells paralleled the acute lung inflammation, which was reflected by ¹⁸F-fluorodeoxyglucose hypermetabolism on positron emission tomography/CT. Tofacitinib lead to a prompt clinical recovery, with a reduction in oxygen requirement, correction of hyperferritinemia, reversal of the natural killer cell deficiency, and a decrease in ¹⁸F-fluorodeoxyglucose uptake in the affected lung segments. Subsequently, nintedanib was added at a point in time when inflammation subsided. Apart from cytomegalovirus reactivation no adverse events occurred. In conclusion, tofacitinib reversed the pronounced inflammatory component of anti-Jo-1 antibody-positive, anti-melanoma differentiation associated gene 5 antibody-negative rapidly progressive interstitial lung disease, confirming that Janus kinase signaling pathways are critically involved in the pathogenesis of rapidly progressive interstitial lung disease, apparently independently of the targeted autoantigen. Although some improvement in pulmonary function was observed, it seems premature to conclusively judge on reversibility or prevention of pulmonary fibrosis by pairing both kinase inhibitors for which an extended follow-up and ideally, prospective and controlled studies are needed.

Cumulative cancer incidence and mortality after kidney transplantation in Japan: A long-term multicenter cohort study

Kidney transplantation is the most promising treatment to improve mortality and life quality in end‐stage kidney disease; however, cancer remains a leading cause of death. Several factors including immunosuppressants might be associated with a gradual increase in cumulative cancer incidence after kidney transplantation. Risk factors for cancer and overall and cancer‐specific survival were analyzed in 1973 kidney transplant recipients from three study institutions in Japan. The 5‐, 10‐, 20‐, and 30‐year overall and cancer‐specific survival rates were 93.3%, 88.4%, 78.0%, and 63.6% and 99.4%, 98.0%, 95.3%, and 91.7%, respectively. The overall survival rate was significantly higher and the graft survival rate was significantly lower in recipients without cancer than in those with cancer. Older recipient age, longer dialysis duration before kidney transplantation, and history of transfusion were significant predictors of cancer. Dialysis duration before kidney transplantation was a prognostic factor of overall survival rate. Regarding cancer‐specific survival rates, older recipient age and dialysis duration before kidney transplantation were prognostic factors of worse cancer‐specific survival rates. The type of immunosuppressant was not associated with an increased cancer rate. Aggressiveness of immunosuppressant regimens or potent immunosuppressants might improve graft survival rate while inducing de novo cancer after kidney transplantation. Older age and longer dialysis duration before kidney transplantation were risk factors of cancer‐specific survival rate.

Tacrolimus Improves the Implantation Rate in Patients with Elevated Th1/2 Helper Cell Ratio and Repeated Implantation Failure (RIF)

Introduction An abnormal endometrial immune response is involved in the pathogenesis of repeated implantation failure (RIF), so we investigated the effectiveness of tacrolimus treatment on the endometrium of RIF patients.

Materials and Methods Ten RIF patients with elevated T-helper 1/T-helper 2 (Th1/Th2) cell ratios were recruited into a clinical study. The expression of p53, leukemia inhibitory factor (LIF), interleukin (IL)-4, IL-10, IL-17, and interferon gamma (IFN-γ) in the endometrium of patients with and without tacrolimus treatment and the association of these factors with assisted reproductive technology (ART) outcomes were investigated.

Results Tacrolimus significantly increased the expression of LIF, IL-10, and IL-17 and decreased the expression of IL-4, IFN-γ, and the IFN-γ/IL-10 ratio in RIF patients. Tacrolimus treatment resulted in an implantation rate of 40%, a clinical pregnancy rate of 50%, and a live birth rate of 35% in RIF patients with elevated Th1/Th2 ratios who had previously failed to become pregnant despite at least three transfers of embryos. We also found a significant positive correlation between IL-10 levels and the implantation rate.

Conclusions Our findings suggest that RIF patients with a higher Th1/Th2 ratio could be candidates for tacrolimus therapy and that this immunosuppressive drug could be acting through upregulation of LIF, IL-10, and IL-17.

A Polyclonal Immune Function Assay Allows Dose-Dependent Characterization of Immunosuppressive Drug Effects but Has Limited Clinical Utility for Predicting Infection on an Individual Basis

Dosage of immunosuppressive drugs after transplantation critically determines rejection and infection episodes. In this study, a global immune function assay was characterized among controls, dialysis-patients, and transplant-recipients to evaluate its utility for pharmacodynamic monitoring of immunosuppressive drugs and for predicting infections. Whole-blood samples were stimulated with anti-CD3/toll-like-receptor (TLR7/8)-agonist in the presence or absence of drugs and IFN-γ secretion was measured by ELISA. Additional stimulation-induced cytokines were characterized among T-, B-, and NK-cells using flow-cytometry. Cytokine-secretion was dominated by IFN-γ, and mainly observed in CD4, CD8, and NK-cells. Intra-assay variability was low (CV = 10.4 ± 6.2%), whereas variability over time was high, even in the absence of clinical events (CV = 65.0 ± 35.7%). Cyclosporine A, tacrolimus and steroids dose-dependently inhibited IFN-γ secretion, and reactivity was further reduced when calcineurin inhibitors were combined with steroids. Moreover, IFN-γ levels significantly differed between controls, dialysis-patients, and transplant-recipients, with lowest IFN-γ levels early after transplantation (p < 0.001). However, a single test had limited ability to predict infectious episodes. In conclusion, the assay may have potential for basic pharmacodynamic characterization of immunosuppressive drugs and their combinations, and for assessing loss of global immunocompetence after transplantation, but its application to guide drug-dosing and to predict infectious on an individual basis is limited.

Mycophenolate mofetil, azathioprine and tacrolimus: mechanisms in rheumatology

The introduction of biologic DMARDs into rheumatology has resulted in a substantial reduction of the burden of many rheumatic diseases. In the slipstream of the success achieved with these biologic DMARDs, some conventional immunosuppressive drugs have also found use in new indications. Notably, mycophenolate mofetil, azathioprine and tacrolimus have made their way from solid organ transplantation drugs to become useful assets in rheumatology practice. Mycophenolate mofetil and azathioprine inhibit the purine pathway and subsequently diminish cell proliferation. Both drugs have a pivotal role in the treatment of various rheumatic diseases, including lupus nephritis. Tacrolimus inhibits lymphocyte activation by inhibiting the calcineurin pathway. Mycophenolate mofetil and tacrolimus are, among other indications, increasingly being recognized as useful drugs in the treatment of interstitial lung disease in systemic rheumatic diseases and skin fibrosis in systemic sclerosis. A broad array of trials with mycophenolate mofetil, azathioprine and/or tacrolimus are ongoing within the field of rheumatology that might provide further novel avenues for the use of these drugs. In this Review, we discuss the historical perspective, pharmacodynamics, clinical indications and novel avenues for mycophenolate mofetil, azathioprine and tacrolimus in rheumatology.

Morbidity, perioperative outcomes and complications of robot-assisted radical prostatectomy in kidney transplant patients: A French multicentre study

OBJECTIVE

Evaluate the safety, feasibility and efficiency of robot-assisted radical prostatectomy (RARP) in kidney transplant recipients, performed in high-volume French referral centres, and describe intra- and postoperative, oncological and functional outcomes.

MATERIALS AND METHODS

A multicentre study was conducted on prospective RARP databases from 5 centres between 2008 and 2017. We retrospectively identified a first group (G1) of transplant patients. The following data were collected: age, body mass index, prostate-specific antigen, ISUP score, TNM stage, stratification according to d'Amico, renal function, renal disease, time between renal transplant and prostate cancer (PCa), operating time, bleeding, pre- and postoperative complications (according to Clavien). Group 1 data were matched with a second group (G2) of nontransplanted PTRA patients.

RESULTS

A total of 321 patients were included (G1 N = 39 and G2 N = 282). The median operating time was 180 minutes (interquartile range 125-227) for G1 and 150 minutes (120-180) in G2 (P = 0.0623) and the median bleeding volume was 150 mL (150-400) and 250 mL (175-400), respectively (P = 0.1826). No grafts were damaged by RARP. Postoperative complication rate was significantly higher in G1: 51.2% vs. G2: 8.2% with a majority of minor complications (41%) according to Clavien Dindo (P < 0.001). Pathological assessment was as follows in G1: T2 = 28 (71.8%), T3 = 11 (28.2%), and G2: T2 = 206 (73.3%), T3 = 75 (26.7%) (P = 0.77). Postoperative ISUP scores were mainly grade 1: G1 = 14 (35.9%) vs. 99 (35.2%) in G2 and grade 2: respectively 18 (46.1%) 94 (33.5%). The rate of positive surgical margins was comparable in both groups: 13.2% for transplant patients vs. 18.1% (P = 0.65). Renal function was not significantly different at one year (P = 0.07). The median follow-up was 47.9 months (42.3; 52.5).

CONCLUSION

RARP is conceivable to treat localized prostate cancer in kidney transplant recipients. This procedure does not appear to have any negative impact on graft renal function and cancer prognosis.

Effects of Antirejection Drugs on Innate Immune Cells After Kidney Transplantation

Over the last decades, our understanding of adaptive immune responses to solid organ transplantation increased considerably and allowed development of immunosuppressive drugs targeting key alloreactive T cells mechanism. As a result, rates of acute rejection dropped and short-term graft survival improved significantly. However, long-term outcomes are still disappointing. Recently, increasing evidence supports that innate immune responses plays roles in allograft rejection and represents a valuable target to further improve long-term allograft survival. Innate immune cells are activated by molecules with stereotypical motifs produced during injury (i.e., damage-associated molecular patterns, DAMPS) or infection (i.e., pathogen-associated molecular patterns, PAMPs). Activated innate immune cells can exert direct pro- and anti-inflammatory effects, while also priming adaptive immune responses. These cells are activated after transplantation by multiple stimuli, including ischemia-reperfusion injury, rejection, and infections. Data from animal models of graft rejection, show that inhibition of innate immunity promotes development of tolerance. Therefore, understanding mechanisms of innate immunity is important to improve graft outcomes. This review discusses effects of currently used immunosuppressive agents on innate immune responses in kidney transplantation.

Natural Killer Cells Promote Kidney Graft Rejection Independently of Cyclosporine A Therapy

Natural Killer (NK) cells have recently been recognized as key players in antibody-mediated chronic allograft failure, thus requiring a comprehensive understanding whether NK cells can escape conventional immunosuppressive regimens. Influence of cyclosporine A (CyA) on NK cell function was studied in a mouse model of allogeneic kidney transplantation (KTX, BALB/c to C57BL/6). Recipients were treated daily with CyA (10 mg/kg) for seven or 14 days for long term survival (day 56). Administration of CyA in recipients resulted in significantly reduced frequencies of intragraft and splenic CD8⁺ T cells, whereas the latter illustrated reduced IFNγ production. In contrast, intragraft and splenic NK cell frequencies remained unaffected in CyA recipients and IFNγ production and degranulation of NK cells were not reduced as compared with controls. Depletion of NK cells in combination with CyA resulted in an improvement in kidney function until day 7 and prolonged graft survival until day 56 as compared to untreated controls. Surviving animals demonstrated higher intragraft frequencies of proliferating CD4⁺FoxP3⁺Ki67⁺ regulatory T (T_REG) cells as well as higher frequencies of CD8⁺CD122⁺ T_REG. We here demonstrate that NK cell depletion combined with CyA synergistically improves graft function and prolongs graft survival, suggesting that NK cell targeting constitutes a novel approach for improving KTX outcomes.

Cancer in kidney transplant recipients

Cancer is the second most common cause of mortality and morbidity in kidney transplant recipients after cardiovascular disease. Kidney transplant recipients have at least a twofold higher risk of developing or dying from cancer than the general population. The increased risk of de novo and recurrent cancer in transplant recipients is multifactorial and attributed to oncogenic viruses, immunosuppression and altered T cell immunity. Transplant candidates and potential donors should be screened for cancer as part of the assessment process. For potential recipients with a prior history of cancer, waiting periods of 2-5 years after remission - largely depending on the cancer type and stage of initial cancer diagnosis - are recommended. Post-transplantation cancer screening needs to be tailored to the individual patient, considering the cancer risk of the individual, comorbidities, overall prognosis and the screening preferences of the patient. In kidney transplant recipients diagnosed with cancer, treatment includes conventional approaches, such as radiotherapy and chemotherapy, together with consideration of altering immunosuppression. As the benefits of transplantation compared with dialysis in potential transplant candidates with a history of cancer have not been assessed, current clinical practice relies on evidence from observational studies and registry analyses.

Small-Molecule Immunosuppressive Drugs and Therapeutic Immunoglobulins Differentially Inhibit NK Cell Effector Functions in vitro

Small-molecule immunosuppressive drugs (ISD) prevent graft rejection mainly by inhibiting T lymphocytes. Therapeutic immunoglobulins (IVIg) are used for substitution, antibody-mediated rejection (AbMR) and HLA-sensitized recipients by targeting distinct cell types. Since the effect of ISD and IVIg on natural killer (NK) cells remains somewhat controversial in the current literature, the aim of this comparative study was to investigate healthy donor's human NK cell functions after exposure to ISD and IVIg, and to comprehensively review the current literature. NK cells were incubated overnight with IL2/IL12 and different doses and combinations of ISD and IVIg. Proliferation was evaluated by ³[H]-thymidine incorporation; phenotype, degranulation and interferon gamma (IFNγ) production by flow cytometry and ELISA; direct NK cytotoxicity by standard ⁵¹[Cr]-release and non-radioactive DELFIA assays using K562 as stimulator and target cells; porcine endothelial cells coated with human anti-pig antibodies were used as targets in antibody-dependent cellular cytotoxicity (ADCC) assays. We found that CD69, CD25, CD54, and NKG2D were downregulated by ISD. Proliferation was inhibited by methylprednisolone (MePRD), mycophenolic acid (MPA), and everolimus (EVE). MePRD and MPA reduced degranulation, MPA only of CD56^bright NK cells. MePRD and IVIg inhibited direct cytotoxicity and ADCC. Combinations of ISD demonstrated cumulative inhibitory effects. IFNγ production was inhibited by MePRD and ISD combinations, but not by IVIg. In conclusion, IVIg, ISD and combinations thereof differentially inhibit NK cell functions. The most potent drug with an effect on all NK functions was MePRD. The fact that MePRD and IVIg significantly block NK cytotoxicity, especially ADCC, has major implications for AbMR as well as therapeutic strategies targeting cancer and immune cells with monoclonal antibodies.

Characteristics of Circulating Natural Killer Cells and Their Interferon-γ Production in Active Adult-onset Still Disease

Objective.

To investigate the characteristics of circulating natural killer (NK) cells and their interferon (IFN)-γ–producing ability in adult-onset Still disease (AOSD).

Methods.

Peripheral blood mononuclear cells were obtained from 22 patients in the acute phase of AOSD (acute AOSD); 7 of the 22 patients after treatment (remission AOSD), and 11 healthy controls (HC). NK cells and their IFN-γ expression levels were analyzed by flow cytometry. Additionally, the cytokine receptors of interleukin (IL)-12, IL-15, and IL-18 on NK cells were also evaluated.

Results.

The frequency of NK cells was significantly lower in acute AOSD than in HC. NK cell counts significantly increased in remission AOSD. Expression of IL-12 and IL-15 receptors on NK cells was significantly increased in acute AOSD, whereas that of IL-18 receptor indicated no significant difference among 3 groups. IFN-γ expression in NK cells was significantly higher in acute AOSD than in HC, and significantly decreased in remission AOSD. The absolute number of NK cells and IFN-γ–expressing NK cells revealed an inverse correlation with serum ferritin levels in acute AOSD. In 2 distinct subsets of NK cells, CD56dim NK cells significantly exhibited higher IFN-γ expression than CD56bright NK cells in acute AOSD.

Conclusion.

In acute AOSD, NK cells displayed lower proportion, whereas they had higher ability for IFN-γ production than in HC; moreover, upregulation of IL-12 and IL-15 receptors on NK cells may promote IFN-γ production. In addition, disease activity may be implicated in regulating the number of NK cells and IFN-γ–expressing NK cells in AOSD.

Natural killer cell function predicts severe infection in kidney transplant recipients

The aim of this study was to determine if natural killer cell number (CD3^- /CD16^± /CD56^± ) and cytotoxic killing function predicts severity and frequency of infection in kidney transplant recipients. A cohort of 168 kidney transplant recipients with stable graft function underwent assessment of natural killer cell number and functional killing capacity immediately prior to entry into this prospective study. Participants were followed for 2 years for development of severe infection, defined as hospitalization for infection. Area under receiver operating characteristic (AUROC) curves were used to evaluate the accuracy of natural killer cell number and function for predicting severe infection. Adjusted odds ratios were determined by logistic regression. Fifty-nine kidney transplant recipients (35%) developed severe infection and 7 (4%) died. Natural killer cell function was a better predictor of severe infection than natural killer cell number: AUROC 0.84 and 0.75, respectively (P = .018). Logistic regression demonstrated that after adjustment for age, transplant function, transplant duration, mycophenolate use, and increasing natural killer function (odds ratio [OR] 0.82, 95% confidence interval [CI] 0.74-0.90; P < .0001) but not natural killer number (OR 0.96, 95% CI 0.93-1.00; P = .051) remained significantly associated with a reduced likelihood of severe infection. Natural killer cell function predicts severe infection in kidney transplant recipients.

Natural killer cells in lung transplantation

Natural killer (NK) cells are innate lymphoid cells that have been increasingly recognised as important in lung allograft tolerance and immune defence. These cells evolved to recognise alterations in self through a diverse set of germline-encoded activating and inhibitory receptors and display a broad range of effector functions that play important roles in responding to infections, malignancies and allogeneic tissue. Here, we review NK cells, their diverse receptors and the mechanisms through which NK cells are postulated to mediate important lung transplant clinical outcomes. NK cells can promote tolerance, such as through the depletion of donor antigen-presenting cells. Alternatively, these cells can drive rejection through cytotoxic effects on allograft tissue recognised as 'non-self' or 'stressed', via killer cell immunoglobulin-like receptor (KIR) or NKG2D receptor ligation, respectively. NK cells likely mediate complement-independent antibody-mediated rejection of allografts though CD16A Fc receptor-dependent activation induced by graft-specific antibodies. Finally, NK cells play an important role in response to infections, particularly by mediating cytomegalovirus infection through the CD94/NKG2C receptor. Despite these sometimes-conflicting effects on allograft function, enumeration of NK cells may have an important role in diagnosing allograft dysfunction. While the effects of immunosuppression agents on NK cells may currently be largely unintentional, further understanding of NK cell biology in lung allograft recipients may allow these cells to serve as biomarkers of graft injury and as therapeutic targets.

Can immune biomarkers predict infections in solid organ transplant recipients? A review of current evidence

Despite improvements in graft survival, solid organ transplantation is still associated with considerable infection induced morbidity and mortality. If we were able to show that serious infection risk was associated with excessive suppression of immune capacity, we would be justified in "personalizing" the extent of immunosuppression by carefully monitored reduction to see if we can improve immune compromize without increasing the risk of rejection. Reliable biomarkers are needed to identify this patients at an increased risk of infection. This review focuses on the currently available evidence in solid organ transplant recipients for immune non-pathogen specific biomarkers to predict severe infections with the susceptibility to particular pathogens according to the component of the immune system that is suppressed. This review is categorized into immune biomarkers representative of the humoral, cellular, phagocytic, natural killer cell and complement system. Biomarkers humoral and cellular systems of the that have demonstrated an association with infections include immunoglobulins, lymphocyte number, lymphocyte subsets, intracellular concentrations of adenosine triphosphate in stimulated CD4⁺ cells and soluble CD30. Biomarkers of the innate immune system that have demonstrated an association with infections include natural killer cell numbers, complement and mannose binding lectin. Emerging evidence shows that quantification of viral nucleic acid (such as Epstein Barr Virus) can act as a biomarker to predict all-cause infections. Studies that show the most promise are those in which several immune biomarkers are assessed in combination. Ongoing research is required to validate non-pathogen specific immune biomarkers in multi-centre studies using standardized study designs.

Cellular senescence as a therapeutic target to improve renal transplantation outcome

Kidney transplants from aged donors are more vulnerable to ischemic injury, suffer more from delayed graft function and have a lower graft survival compared to kidneys from younger donors. On a cellular level, aging results in an increase in cells that are in a permanent cell cycle arrest, termed senescence, which secrete a range of pro-inflammatory cytokines and growth factors. Consequently, these senescent cells negatively influence the local milieu by causing inflammaging, and by reducing the regenerative capacity of the kidney. Moreover, the oxidative damage that is inflicted by ischemia-reperfusion injury during transplantation can induce senescence and accelerate aging. In this review, we describe recent developments in the understanding of the biology of aging that have led to the development of a new class of therapeutic agents aimed at eliminating senescent cells. These compounds have already shown to be able to restore tissue homeostasis in old mice, improve kidney function and general health- and lifespan. Use of these anti-senescence compounds holds great promise to improve the quality of marginal donor kidneys as well as to remove senescent cells induced by ischemia-reperfusion injury. Altogether, senescent cell removal may increase the donor pool, relieving the growing organ shortage and improve long-term transplantation outcome.

Impact of Steroids on Natural Killer Cells Against Cytotoxicity and Hepatitis C Virus Replication

BACKGROUND

Natural killer (NK) cells play important roles in killing tumor and virus-infected cells. Immunosuppression used after organ transplantation is thought to increase the risk of tumor recurrence and viral infections. However, the effect of immunosuppressive drugs on NK cells has not yet been clearly established. Therefore, we examined the effect of immunosuppression on NK cells.

METHODS

NK cells were cultured for 7 days in the presence of interleukin-2 (100 U/mL) with or without the following immunosuppressive drugs: tacrolimus, cyclosporine A, corticosteroid (methylprednisolone [MP]), mycophenolate mofetil, and rapamycin. The effect of the drugs on NK cell activation was tested on the basis of the following: NK cell phenotype, NK cell proliferation, cytotoxicity against K562 cells, cytokine production by NK cells, and anti-hepatitis C virus (HCV) activity with HCV genomic replicon cells.

RESULTS

NK cells showed relatively robust functions in the presence of tacrolimus and cyclosporine A. Mycophenolate mofetil and rapamycin significantly prevented only NK cell proliferation (P < .05). In contrast, MP significantly inhibited the proliferation, cytotoxicity, and anti-HCV effect (10.9%, 18.5%, and 1.9%, respectively) of NK cells. Furthermore, MP specifically inhibited the expression of NK cell activation markers and the production of interferon-γ (P < .05).

CONCLUSIONS

Corticosteroids have distinct effects on NK cells, which may have important implications for NK cell function in cytotoxicity and HCV effect after transplantation.

The Role of NK Cells in Pig-to-Human Xenotransplantation

Recruitment of human NK cells to porcine tissues has been demonstrated in pig organs perfused ex vivo with human blood in the early 1990s. Subsequently, the molecular mechanisms leading to adhesion and cytotoxicity in human NK cell-porcine endothelial cell (pEC) interactions have been elucidated in vitro to identify targets for therapeutic interventions. Specific molecular strategies to overcome human anti-pig NK cell responses include (1) blocking of the molecular events leading to recruitment (chemotaxis, adhesion, and transmigration), (2) expression of human MHC class I molecules on pECs that inhibit NK cells, and (3) elimination or blocking of pig ligands for activating human NK receptors. The potential of cell-based strategies including tolerogenic dendritic cells (DC) and regulatory T cells (Treg) and the latest progress using transgenic pigs genetically modified to reduce xenogeneic NK cell responses are discussed. Finally, we present the status of phenotypic and functional characterization of nonhuman primate (NHP) NK cells, essential for studying their role in xenograft rejection using preclinical pig-to-NHP models, and summarize key advances and important perspectives for future research.

Dual Role of Natural Killer Cells on Graft Rejection and Control of Cytomegalovirus Infection in Renal Transplantation

Allograft rejection constitutes a major complication of solid organ transplantation requiring prophylactic/therapeutic immunosuppression, which increases susceptibility of patients to infections and cancer. Beyond the pivotal role of alloantigen-specific T cells and antibodies in the pathogenesis of rejection, natural killer (NK) cells may display alloreactive potential in case of mismatch between recipient inhibitory killer-cell immunoglobulin-like receptors (KIRs) and graft HLA class I molecules. Several studies have addressed the impact of this variable in kidney transplant with conflicting conclusions; yet, increasing evidence supports that alloantibody-mediated NK cell activation via FcγRIIIA (CD16) contributes to rejection. On the other hand, human cytomegalovirus (HCMV) infection constitutes a risk factor directly associated with the rate of graft loss and reduced host survival. The levels of HCMV-specific CD8⁺ T cells have been reported to predict the risk of posttransplant infection, and KIR-B haplotypes containing activating KIR genes have been related with protection. HCMV infection promotes to a variable extent an adaptive differentiation and expansion of a subset of mature NK cells, which display the CD94/NKG2C-activating receptor. Evidence supporting that adaptive NKG2C⁺ NK cells may contribute to control the viral infection in kidney transplant recipients has been recently obtained. The dual role of NK cells in the interrelation of HCMV infection with rejection deserves attention. Further phenotypic, functional, and genetic analyses of NK cells may provide additional insights on the pathogenesis of solid organ transplant complications, leading to the development of biomarkers with potential clinical value.

STAT4-associated natural killer cell tolerance following liver transplantation

OBJECTIVE

Natural killer (NK) cells are important mediators of liver inflammation in chronic liver disease. The aim of this study was to investigate why liver transplants (LTs) are not rejected by NK cells in the absence of human leukocyte antigen (HLA) matching, and to identify a tolerogenic NK cell phenotype.

DESIGN

Phenotypic and functional analyses on NK cells from 54 LT recipients were performed, and comparisons made with healthy controls. Further investigation was performed using gene expression analysis and donor:recipient HLA typing.

RESULTS

NK cells from non-HCV LT recipients were hypofunctional, with reduced expression of NKp46 (p<0.05) and NKp30 (p<0.001), reduced cytotoxicity (p<0.001) and interferon (IFN)-γ secretion (p<0.025). There was no segregation of this effect with HLA-C, and these functional changes were not observed in individuals with HCV. Microarray and RT-qPCR analysis demonstrated downregulation of STAT4 in NK cells from LT recipients (p<0.0001). Changes in the expression levels of the transcription factors Helios (p=0.06) and Hobit (p=0.07), which control NKp46 and IFNγ expression, respectively, were also detected. Hypofunctionality of NK cells was associated with impaired STAT4 phosphorylation and downregulation of the STAT4 target microRNA-155. Conversely in HCV-LT NK cell tolerance was reversed, consistent with the more aggressive outcome of LT for HCV.

CONCLUSIONS

LT is associated with transcriptional and functional changes in NK cells, resulting in reduced activation. NK cell tolerance occurs upstream of major histocompatibility complex (MHC) class I mediated education, and is associated with deficient STAT4 phosphorylation. STAT4 therefore represents a potential therapeutic target to induce NK cell tolerance in liver disease.

Natural Killer Cell Subsets and IL-2, IL-15, and IL-18 Genes Expressions in Chronic Kidney Allograft Dysfunction and Graft Function in Kidney Allograft Recipients

BACKGROUND

While acute rejection and early graft loss rates have decreased substantially over the past four decades, progressive chronic allograft dysfunction (CAD) still remains a common cause of late graft loss in kidney transplant recipients.

OBJECTIVE

This study was conducted to investigate the percentage of natural killer (NK) cell subsets and IL-2, 15 and 18 genes expression in two groups of CAD and well-function graft (WFG) recipients.

METHODS

30 renal allograft recipients with biopsy-proven interstitial fibrosis/tubular atrophy (IF/TA) and impaired renal function, and 30 sex- and age-matched WFG patients were enrolled in this study. The percentage of NK cell subsets including NK CD56bright and NK CD56dim cells were determined by flowcytometry; IL-2, IL-15, and IL-18 genes expressions were assessed by real-time PCR.

RESULTS

Compared to WFG patients, there was a significant (p<0.05) increase in the percentage of NK CD56bright cells in CAD patients. However, the difference in percentage of NK CD56dim cells or CD56dim/CD56bright ratio between the studied groups was not significant. In addition, IL-2, 15 and 18 genes expressions were almost similar in CAD and WFG patients.

CONCLUSION

We found higher percentages of NK CD56bright subset in kidney transplant recipients with CAD without considerable changes in related cytokines' gene expression, suggesting a possible defect of NK cells maturation in these patients.

Antibody-Dependent NK Cell Activation Is Associated with Late Kidney Allograft Dysfunction and the Complement-Independent Alloreactive Potential of Donor-Specific Antibodies

Although kidney transplantation remains the best treatment for end-stage renal failure, it is limited by chronic humoral aggression of the graft vasculature by donor-specific antibodies (DSAs). The complement-independent mechanisms that lead to the antibody-mediated rejection (ABMR) of kidney allografts remain poorly understood. Increasing lines of evidence have revealed the relevance of natural killer (NK) cells as innate immune effectors of antibody-dependent cellular cytotoxicity (ADCC), but few studies have investigated their alloreactive potential in the context of solid organ transplantation. Our study aimed to investigate the potential contribution of the antibody-dependent alloreactive function of NK cells to kidney graft dysfunction. We first conducted an observational study to investigate whether the cytotoxic function of NK cells is associated with chronic allograft dysfunction. The NK-Cellular Humoral Activation Test (NK-CHAT) was designed to evaluate the recipient and antibody-dependent reactivity of NK cells against allogeneic target cells. The release of CD107a/Lamp1⁺ cytotoxic granules, resulting from the recognition of rituximab-coated B cells by NK cells, was analyzed in 148 kidney transplant recipients (KTRs, mean graft duration: 6.2 years). Enhanced ADCC responsiveness was associated with reduced graft function and identified as an independent risk factor predicting a decline in the estimated glomerular filtration rate over a 1-year period (hazard ratio: 2.83). In a second approach, we used the NK-CHAT to reveal the cytotoxic potential of circulating alloantibodies in vitro. The level of CD16 engagement resulting from the in vitro recognition of serum-coated allogeneic B cells or splenic cells was further identified as a specific marker of DSA-induced ADCC. The NK-CHAT scoring of sera obtained from 40 patients at the time of transplant biopsy was associated with ABMR diagnosis. Our findings indicate that despite the administration of immunosuppressive treatments, robust ADCC responsiveness can be maintained in some KTRs. Because it evaluates both the Fab recognition of alloantigens and Fc-driven NK cell activation, the NK-CHAT represents a potentially valuable tool for the non-invasive and individualized evaluation of humoral risk during transplantation.

Standardised incidence ratios (SIRs) for cancer after renal transplant in systemic lupus erythematosus (SLE) and non-SLE recipients

OBJECTIVE

We investigated malignancy risk after renal transplantation in patients with and without systemic lupus erythematosus (SLE).

METHODS

Using the United States Renal Data System from 2001 to 2009, 143 652 renal transplant recipients with and without SLE contributed 585 420 patient-years of follow-up to determine incident cancers using Medicare claims codes. We calculated standardised incidence ratios (SIRs) of cancer by group using age, sex, race/ethnicity-specific and calendar year-specific cancer rates compared with the US population.

RESULTS

10 160 cancers occurred at least 3 months after renal transplant. Overall cancer risk was increased in both SLE and non-SLE groups compared with the US general population, SIR 3.5 (95% CI 2.1 to 5.7) and SIR 3.7 (95% CI 2.4 to 5.7), respectively. Lip/oropharyngeal, Kaposi, neuroendocrine, thyroid, renal, cervical, lymphoma, liver, colorectal and breast cancers were increased in both groups, whereas only melanoma was increased in SLE and lung cancer was increased in non-SLE. In Cox regression analysis, SLE status (HR 1.1, 95% CI 0.9 to 1.3) was not associated with increased risk of developing cancer, adjusted for other independent risk factors for developing cancer in renal transplant recipients. We found that smoking (HR 2.2, 95% CI 1.2 to 4.0), cytomegalovirus positivity at time of transplant (HR 1.3, 95% CI 1.2 to 1.4), white race (HR 1.2, 95% CI 1.2 to 1.3) and older recipient age at time of transplantation (HR 1.0 95% CI 1.0 to 1.2) were associated with an increased risk for development of cancer, whereas shorter time on dialysis, Epstein-Barr virus or HIV were associated with a lower risk for development of cancer.

CONCLUSIONS

Cancer risk in renal transplant recipients appeared similar in SLE and non-SLE subjects, aside from melanoma. Renal transplant recipients may need targeted counselling regarding surveillance and modifiable risk factors.

Added effects of dexamethasone and mesenchymal stem cells on early Natural Killer cell activation

Graft rejection and graft-versus-host disease are leading causes of transplant related mortality despite advancements in immunosuppressive therapy. Mesenchymal stem cells (MSCs) offer a promising addition to immunosuppressive drugs (ISD), while NK-cells are increasingly used as effector cells in graft-versus-leukemia. Combined therapy of ISD, NK-cells and/or MSCs is used in clinical practice. Here, we examined the effects of MSCs and selected ISD (tacrolimus, cyclosporin A, mycophenolic acid, dexamethasone) treatment on early NK-cell activation. We assessed STAT4 and STAT5 phosphorylation triggered by IL-12 and IL-2, respectively. Furthermore, we determined IFNγ, perforin production and the expression pattern of selected NK-cell receptors. Of all drugs tested, only dexamethasone inhibited NK-cell STAT4 and STAT5 phosphorylation. All ISD, with the exception of MPA, significantly inhibited IFNγ, and only dexamethasone inhibited upregulation of early activation markers CD69 and CD25 (IL-2 condition only). MSCs inhibited IL-2 induced NK cell STAT5 phosphorylation, IFNγ production and CD69 upregulation, and IL-12 induced IFNγ and perforin production. While MSCs mediated inhibition of CD69 expression was cell contact dependent, inhibition of IFNγ and perforin production, as well as STAT5 phosphorylation was cell-contact independent. Importantly, dexamethasone augmented MSCs mediated inhibition of both IL-12 and IL-2 induced CD69 expression and IFNγ production, as well as IL-2 induced STAT5 phosphorylation. Taken together, these novel insights may help the design of future NK-cell and MSCs based immunotherapy.

Natural Killer Lymphocytes Are Dysfunctional in Kidney Transplant Recipients on Diagnosis of Cancer

BACKGROUND

The incidence of cancer is increased after solid organ transplantation. Natural killer (NK) cells are key effectors of the tumor immune response.

METHODS

We conducted a cross sectional multicentre matched case-control study including 42 kidney transplant recipients (KTRs) on diagnosis of cancer and 41 KTRs without cancer. Extensive phenotyping of NK cells populations and functional tests of NK cells were performed.

RESULTS

Kidney transplant recipients with cancer had a higher incidence of acute rejection (P = 0.02) and cytomegalovirus (CMV) infection (P = 0.03) than controls. They had more lymphopenia than control KTRs (1020/mm3 +/- 32 vs 1218/mm3 +/- 34; P = 0.001) including a CD4+ lymphopenia (P = 0.01). Total CD3-/CD56+ NK cell counts were similar in both groups. However, KTRs with cancer had a lower frequency of the cytokine-enriched CD56bright NK cell subset (P = 0.001). The percentage of NK cells expressing NKp46 was decreased in KTRs with cancer (45% vs 53 %, P = 0.001). Furthermore, the ability of NK cells to degranulate CD107a+ cytolytic vesicles was reduced (11% vs 22%; P = 0.02), and the percentage of NK cells secreting IFN[gamma] was decreased (7.5% vs 28.8%; P = 0.01) in KTRs with cancer.

CONCLUSIONS

These results reveal an imbalance between NK cell subpopulations and functional NK cell defects in KTRs at the diagnosis of malignancy, including a decreased expression of NKp46 and decreased numbers of NK cells producing INF[gamma]. This study highlights the role of NKp46, a major activating NK cell receptor, which could be considered as a potential marker during immunological follow-up of KTRs.

Teratocarcinomas Arising from Allogeneic Induced Pluripotent Stem Cell-Derived Cardiac Tissue Constructs Provoked Host Immune Rejection in Mice

Transplantation of induced pluripotent stem cell-derived cardiac tissue constructs is a promising regenerative treatment for cardiac failure: however, its tumourigenic potential is concerning. We hypothesised that the tumourigenic potential may be eliminated by the host immune response after allogeneic cell transplantation. Scaffold-free iPSC-derived cardaic tissue sheets of C57BL/6 mouse origin were transplanted into the cardiac surface of syngeneic C57BL/6 mice and allogeneic BALB/c mice with or without tacrolimus injection. Syngeneic mice and tacrolimus-injected immunosuppressed allogeneic mice formed teratocarcinomas with identical phenotypes, characteristic, and time courses, as assessed by imaging tools including ¹⁸F-fluorodeoxyglucose-positron emission tomography. In contrast, temporarily immunosuppressed allogeneic mice, following cessation of tacrolimus injection displayed diminished progression of the teratocarcinoma, accompanied by an accumulation of CD4/CD8-positive T cells, and finally achieved complete elimination of the teratocarcinoma. Our results indicated that malignant teratocarcinomas arising from induced pluripotent stem cell-derived cardiac tissue constructs provoked T cell-related host immune rejection to arrest tumour growth in murine allogeneic transplantation models.

A phase I/II trial of interleukin-15--stimulated natural killer cell infusion after haplo-identical stem cell transplantation for pediatric refractory solid tumors

BACKGROUND AIMS

Preliminary data suggest that T-cell-depleted haplo-identical stem cell transplantation (haplo-SCT) has a clinically beneficial allograft-versus-tumor effect associated with natural killer (NK) cell immune reconstitution.

METHODS

This phase I/II trial descriptively evaluates the feasibility of interleukin (IL)-15-stimulated NK cell infusion after haplo-SCT in pediatric patients with refractory solid tumors.

RESULTS

Six patients received an IL-15-stimulated NK cell infusion at 30 days after haplo-SCT. The mean number of infused NK cells per product was 11.3 × 10(6)/kg (range, 3-27 × 10(6)/kg). The T-cell count was <1 × 10(3)/kg in all patients (range, 0-0.75 × 10(3)/kg). No toxic effects related to IL-15--stimulated NK cell infusion were observed. Four of the six patients showed a clinical response (one achieved very good partial remission, two achieved partial remission and one had stable disease). One patient had progressive disease, and the response was not evaluated in the remaining patient. After a median follow-up period of 310 days, all patients had died: four of cancer relapse, one of cancer-associated thrombotic micro-angiopathy and one of acute graft-versus-host disease.

CONCLUSIONS

The adoptive transfer of allogeneic IL-15--stimulated NK cells might be feasible and safe in heavily pretreated pediatric patients with refractory solid tumors, though the advanced stage of disease and toxic effects of haplo-SCT may limit the efficacy of NK cell infusion in this population.

Immune profiling and cancer post transplantation

Half of all long-term (> 10 year) australian kidney transplant recipients (KTR) will develop squamous cell carcinoma (SCC) or solid organ cancer (SOC), making cancer the leading cause of death with a functioning graft. At least 30% of KTR with a history of SCC or SOC will develop a subsequent SCC or SOC lesion. Pharmacological immunosuppression is a major contributor of the increased risk of cancer for KTR, with the cancer lesions themselves further adding to systemic immunosuppression and could explain, in part, these phenomena. Immune profiling includes; measuring immunosuppressive drug levels and pharmacokinetics, enumerating leucocytes and leucocyte subsets as well as testing leucocyte function in either an antigen specific or non-specific manner. Outputs can vary from assay to assay according to methods used. In this review we define the rationale behind post-transplant immune monitoring assays and focus on assays that associate and/or have the ability to predict cancer and rejection in the KTR. We find that immune monitoring can identify those KTR of developing multiple SCC lesions and provide evidence they may benefit from pharmacological immunosuppressive drug dose reductions. In these KTR risk of rejection needs to be assessed to determine if reduction of immunosuppression will not harm the graft.

Limited efficacy of immunosuppressive drugs on CD8+ T cell-mediated and natural killer cell-mediated lysis of human renal tubular epithelial cells

BACKGROUND

Although CD8+ T cell-mediated and natural killer (NK) cell-mediated cytotoxicity against renal tubular epithelial cells (TECs) plays a crucial role during rejection, the degree of inhibition of these lytic immune responses by immunosuppressive drugs is unknown. We investigated the CD8 T-cell and NK cell responses induced by TECs in vitro and questioned how these processes are affected by immunosuppressive drugs.

METHODS

Donor-derived TECs were co-cultured with recipient peripheral blood monocyte cells. Proliferation of CD8+ T cells and NK cell subsets was assessed using PKH dilution assay. CD107a degranulation and europium release assay were performed to explore CD8+-mediated and NK cell-mediated TEC lysis. Experiments were conducted in the absence or presence of tacrolimus (10 ng/mL), everolimus (10 ng/mL), and prednisolone (200 ng/mL).

RESULTS

Tubular epithelial cells induce significant CD8+ T-cell and NK cell proliferation. All immunosuppressive drugs significantly inhibited TEC-induced CD8+ T-cell proliferation. Interestingly, prednisolone was the most powerful inhibitor of NK cell proliferation. CD8-mediated and NK cell-mediated early lytic responses were marked by strong degranulation after an encounter of unstimulated TECs, represented by a high cell surface expression of CD107a. However, with the use of interferon-γ-activated and tumor necrosis factor-α-activated TECs, the NK degranulation response was significantly reduced and CD8 degranulation response was even more enhanced (P<0.05). Tubular epithelial cell-induced CD8 degranulation and CD8-mediated TEC lysis were preferentially inhibited by tacrolimus and prednisolone, and not by everolimus. Although tacrolimus showed the most inhibitory effect on the degranulation of NK cells, NK cell-mediated TEC lysis was efficiently inhibited by prednisolone (P<0.05).

CONCLUSION

Overall, our data point to a limited efficacy of immunosuppressive drugs on CD8+ T cell-mediated and NK cell-mediated lysis of human renal TECs.

Immunomodulatory activity of commonly used drugs on Fc-receptor-mediated human natural killer cell activation

Natural killer (NK) cells mediate defense against neoplastic as well as infected cells. Yet, how their effector functions are affected by the large variety of pharmacological compounds commonly in use has not been investigated systematically. Here, we screened 1,200 in-use or previously approved drugs for their biological effect on freshly isolated human peripheral blood-derived NK cells. Mimicking antibody-dependent cellular cytotoxicity (ADCC), known to be important in antibody-based immunotherapies against, e.g., human malignancies, the cells were stimulated by Fc-receptor (CD16) engagement. Cellular responses were assessed by flow cytometry. Fifty-six compounds that significantly inhibited and twelve that enhanced one or more of the readouts of adhesion, exocytosis, and chemokine production were identified and confirmed as hits. Among the confirmed inhibitors, 80 % could be assigned to one of seven major pharmacological classes. These classes were β2-adrenergic agonists, prostaglandins, phosphodiesterase-4 inhibitors, Ca(2+)-channel blockers, histamine H1-receptor antagonists, serotonin/dopamine receptor antagonists, and topoisomerase inhibitors that displayed distinct inhibitory patterns on NK cell responses. Among observed enhancers, interestingly, two ergosterol synthesis inhibitors were identified that specifically promoted exocytosis. In summary, these results provide a comprehensive knowledge base of the effect known drugs have on NK cells. More specifically, they provide an overview of drugs that may modulate NK cell-mediated ADCC in the context of clinical immunotherapies.

Regulation of anti-HLA antibody-dependent natural killer cell activation by immunosuppressive agents

BACKGROUND

It was demonstrated that human natural killer (NK) cells, via antibody-dependent cellular cytotoxicity (ADCC)-like mechanism, increase IFNγ production after exposure to alloantigens. This finding was associated with an increased risk for antibody-mediated rejection (ABMR). Although the effects of various immunosuppressive drugs on T cells and B cells have been extensively studied, their effects on NK cells are less clear. This study reports the effect of immunosuppressive agents on antibody-mediated NK cell activation in vitro.

METHODS

Whole blood from normal individuals was incubated with irradiated peripheral blood mononuclear cells (PBMCs) pretreated with anti-HLA antibody+ sera (in vitro ADCC), with or without immunosuppressive agents. The %IFNγ+ and CD107a+ (degranulation marker) in CD56+ NK cells were enumerated by flow cytometry.

RESULTS

Cyclosporine A and tacrolimus significantly reduced IFNγ production in a dose-dependent manner (53%-83%), but showed minimal effect on degranulation (20%). Prednisone significantly reduced both IFNγ production and degranulation (50%-66% reduction at maximum therapeutic levels). Calcineurin inhibitors (CNIs) in combination with prednisone additively suppressed IFNγ production and degranulation. The effect of sirolimus or mycophenolate mofetil on NK cells was minimal.

CONCLUSIONS

These results suggest that potent suppressive effects of CNIs and prednisone on antibody-mediated NK cell activation may contribute to the reduction of ADCC in sensitized patients and possibly reduce the risk for ADCC-mediated ABMR. These further underscore the importance of medication compliance in prevention of ABMR and possibly chronic rejection, and suggest that ADCC-mediated injury may increase in strategies aimed at CNI or steroid minimization or avoidance.

Impact of commonly used transplant immunosuppressive drugs on human NK cell function is dependent upon stimulation condition

Lung transplantation is a recognised treatment for patients with end stage pulmonary disease. Transplant recipients receive life-long administration of immunosuppressive drugs that target T cell mediated graft rejection. However little is known of the impact on NK cells, which have the potential to be alloreactive in response to HLA-mismatched ligands on the lung allograft and in doing so, may impact negatively on allograft survival. NK cells from 20 healthy controls were assessed in response to Cyclosporine A, Mycophenolic acid (MPA; active form of Mycophenolate mofetil) and Prednisolone at a range of concentrations. The impact of these clinically used immunosuppressive drugs on cytotoxicity (measured by CD107a expression), IFN-γ production and CFSE proliferation was assessed in response to various stimuli including MHC class-I negative cell lines, IL-2/IL-12 cytokines and PMA/Ionomycin. Treatment with MPA and Prednisolone revealed significantly reduced CD107a expression in response to cell line stimulation. In comparison, addition of MPA and Cyclosporine A displayed reduced CD107a expression and IFN-γ production following PMA/Ionomycin stimulation. Diminished proliferation was observed in response to treatment with each drug. Additional functional inhibitors (LY294002, PD98059, Rottlerin, Rapamycin) were used to elucidate intracellular pathways of NK cell activation in response to stimulation with K562 or PMA-I. CD107a expression was significantly decreased with the addition of PD98059 following K562 stimulation. Similarly, CD107a expression significantly decreased following PMA-I stimulation with the addition of LY294002, PD98059 and Rottlerin. Ten lung transplant patients, not receiving immunosuppressive drugs pre-transplant, were assessed for longitudinal changes post-transplant in relation to the administration of immunosuppressive drugs. Individual patient dynamics revealed different longitudinal patterns of NK cell function post-transplantation. These results provide mechanistic insights into pathways of NK cell activation and show commonly administered transplant immunosuppression agents and clinical rejection/infection events have differential effects on NK cell function that may impact the immune response following lung transplantation.