Progress in Transplantation: Will It Be Achieved in Big Steps or by Marginal Gains?

Association between arterial oxygen and mortality across critically ill patients with hematologic malignancies: results from an international collaborative network

PURPOSE

Patients with hematological malignancies are at high risk for life-threatening complications. To date, little attention has been paid to the impact of hyperoxemia and excess oxygen use on mortality. The aim of this study was to investigate the association between partial pressure of arterial oxygen (PaO2) and 28-day mortality in critically ill patients with hematologic malignancies.

METHODS

Data from three international cohorts (Europe, Canada, Oceania) of patients who received respiratory support (noninvasive ventilation, high-flow nasal cannula, invasive mechanical ventilation) were obtained. We used mixed-effect Cox models to investigate the association between day one PaO2 or excess oxygen use (inspired fraction of oxygen ≥ 0.6 with PaO2 > 100 mmHg) on day-28 mortality.

RESULTS

11,249 patients were included. On day one, 5716 patients (50.8%) had normoxemia (60 ≤ PaO2 ≤ 100 mmHg), 1454 (12.9%) hypoxemia (PaO2 < 60 mmHg), and 4079 patients (36.3%) hyperoxemia (PaO2 > 100 mmHg). Excess oxygen was used in 2201 patients (20%). Crude day-28 mortality rate was 40.6%. There was a significant association between PaO2 and day-28 mortality with a U-shaped relationship (p < 0.001). Higher PaO2 levels (> 100 mmHg) were associated with day-28 mortality with a dose-effect relationship. Subgroup analyses showed an association between hyperoxemia and mortality in patients admitted with neurological disorders; however, the opposite relationship was seen across those admitted with sepsis and neutropenia. Excess oxygen use was also associated with subsequent day-28 mortality (adjusted hazard ratio (aHR) [95% confidence interval (CI)]: 1.11[1.04-1.19]). This result persisted after propensity score analysis (matched HR associated with excess oxygen:1.31 [1.20-1.1.44]).

CONCLUSION

In critically-ill patients with hematological malignancies, exposure to hyperoxemia and excess oxygen use were associated with increased mortality, with variable magnitude across subgroups. This might be a modifiable factor to improve mortality.

Advancement in preoperative desensitization therapy for ABO incompatible kidney transplantation recipients

ABO incompatibility has long been considered an absolute contraindication for kidney transplantation. However, with the increasing number of patients with ESRD in recent years, ABO-incompatible kidney transplantation (ABOi-KT) has expanded the types of donors by crossing the blood group barrier through preoperative desensitization therapy. At present, the desensitization protocols consist of removal of preexisting ABO blood group antibody titers and prevention of ABO blood group antibody return. Studies have suggested similar patient and graft survival among ABOi-KT and ABOc-KT recipients. In this review, we will summarize the effective desensitization regimens of ABOi-KT, aiming to explore effective ways to improve the success rate and the long-term survival rate of ABOi-KT recipients.

Unveiling the Hidden Power of Uromodulin: A Promising Potential Biomarker for Kidney Diseases

Uromodulin, also known as Tamm-Horsfall protein, represents the predominant urinary protein in healthy individuals. Over the years, studies have revealed compelling associations between urinary and serum concentrations of uromodulin and various parameters, encompassing kidney function, graft survival, cardiovascular disease, glucose metabolism, and overall mortality. Consequently, there has been a growing interest in uromodulin as a novel and effective biomarker with potential applications in diverse clinical settings. Reduced urinary uromodulin levels have been linked to an elevated risk of acute kidney injury (AKI) following cardiac surgery. In the context of chronic kidney disease (CKD) of different etiologies, urinary uromodulin levels tend to decrease significantly and are strongly correlated with variations in estimated glomerular filtration rate. The presence of uromodulin in the serum, attributable to basolateral epithelial cell leakage in the thick ascending limb, has been observed. This serum uromodulin level is closely associated with kidney function and histological severity, suggesting its potential as a biomarker capable of reflecting disease severity across a spectrum of kidney disorders. The UMOD gene has emerged as a prominent locus linked to kidney function parameters and CKD risk within the general population. Extensive research in multiple disciplines has underscored the biological significance of the top UMOD gene variants, which have also been associated with hypertension and kidney stones, thus highlighting the diverse and significant impact of uromodulin on kidney-related conditions. UMOD gene mutations are implicated in uromodulin-associated kidney disease, while polymorphisms in the UMOD gene show a significant association with CKD. In conclusion, uromodulin holds great promise as an informative biomarker, providing valuable insights into kidney function and disease progression in various clinical scenarios. The identification of UMOD gene variants further strengthens its relevance as a potential target for better understanding kidney-related pathologies and devising novel therapeutic strategies. Future investigations into the roles of uromodulin and regulatory mechanisms are likely to yield even more profound implications for kidney disease diagnosis, risk assessment, and management.

Pretransplant Serum Uromodulin and Its Association with Delayed Graft Function Following Kidney Transplantation-A Prospective Cohort Study

Delayed graft function (DGF) following kidney transplantation is associated with increased risk of graft failure, but biomarkers to predict DGF are scarce. We evaluated serum uromodulin (sUMOD), a potential marker for tubular integrity with immunomodulatory capacities, in kidney transplant recipients and its association with DGF. We included 239 kidney transplant recipients and measured sUMOD pretransplant and on postoperative Day 1 (POD1) as independent variables. The primary outcome was DGF, defined as need for dialysis within one week after transplantation. In total, 64 patients (27%) experienced DGF. In multivariable logistic regression analysis adjusting for recipient, donor and transplant associated risk factors each 10 ng/mL higher pretransplant sUMOD was associated with 47% lower odds for DGF (odds ratio (OR) 0.53, 95% confidence interval (95%-CI) 0.30–0.82). When categorizing pretransplant sUMOD into quartiles, the quartile with the lowest values had 4.4-fold higher odds for DGF compared to the highest quartile (OR 4.41, 95%-CI 1.54–13.93). Adding pretransplant sUMOD to a model containing established risk factors for DGF in multivariable receiver-operating-characteristics (ROC) curve analysis, the area-under-the-curve improved from 0.786 [95%-CI 0.723–0.848] to 0.813 [95%-CI 0.755–0.871, p = 0.05]. SUMOD on POD1 was not associated with DGF. In conclusion, higher pretransplant sUMOD was independently associated with lower odds for DGF, potentially serving as a non-invasive marker to stratify patients according to their risk for developing DGF early in the setting of kidney transplantation.

Humanized Mouse Model as a Novel Approach in the Assessment of Human Allogeneic Responses in Organ Transplantation

The outcome of organ transplantation is largely dictated by selection of a well-matched donor, which results in less chance of graft rejection. An allogeneic immune response is the main immunological barrier for successful organ transplantation. Donor and recipient human leukocyte antigen (HLA) mismatching diminishes outcomes after solid organ transplantation. The current evaluation of HLA incompatibility does not provide information on the immunogenicity of individual HLA mismatches and impact of non-HLA-related alloantigens, especially in vivo. Here we demonstrate a new method for analysis of alloimmune responsiveness between donor and recipient in vivo by introducing a humanized mouse model. Using molecular, cellular, and genomic analyses, we demonstrated that a recipient's personalized humanized mouse provided the most sensitive assessment of allogeneic responsiveness to potential donors. In our study, HLA typing provided a better recipient-donor match for one donor among two related donors. In contrast, assessment of an allogeneic response by mixed lymphocyte reaction (MLR) was indistinguishable between these donors. We determined that, in the recipient's humanized mouse model, the donor selected by HLA typing induced the strongest allogeneic response with markedly increased allograft rejection markers, including activated cytotoxic Granzyme B-expressing CD8+ T cells. Moreover, the same donor induced stronger upregulation of genes involved in the allograft rejection pathway as determined by transcriptome analysis of isolated human CD45+cells. Thus, the humanized mouse model determined the lowest degree of recipient-donor alloimmune response, allowing for better selection of donor and minimized immunological risk of allograft rejection in organ transplantation. In addition, this approach could be used to evaluate the level of alloresponse in allogeneic cell-based therapies that include cell products derived from pluripotent embryonic stem cells or adult stem cells, both undifferentiated and differentiated, all of which will produce allogeneic immune responses.

Survival in Immunocompromised Patients Ultimately Requiring Invasive Mechanical Ventilation: A Pooled Individual Patient Data Analysis

Rationale: Acute respiratory failure (ARF) is associated with high mortality in immunocompromised patients, particularly when invasive mechanical ventilation is needed. Therefore, noninvasive oxygenation/ventilation strategies have been developed to avoid intubation, with uncertain impact on mortality, especially when intubation is delayed. Objectives: We sought to report trends of survival over time in immunocompromised patients receiving invasive mechanical ventilation. The impact of delayed intubation after failure of noninvasive strategies was also assessed. Methods: Systematic review and meta-analysis using individual patient data of studies that focused on immunocompromised adult patients with ARF requiring invasive mechanical ventilation. Studies published in English were identified through PubMed, Web of Science, and Cochrane Central (2008-2018). Individual patient data were requested from corresponding authors for all identified studies. We used mixed-effect models to estimate the effect of delayed intubation on hospital mortality and described mortality rates over time. Measurements and Main Results: A total of 11,087 patients were included (24 studies, three controlled trials, and 21 cohorts), of whom 7,736 (74%) were intubated within 24 hours of ICU admission (early intubation). The crude mortality rate was 53.2%. Adjusted survivals improved over time (from 1995 to 2017, odds ratio [OR] for hospital mortality per year, 0.96 [0.95-0.97]). For each elapsed day between ICU admission and intubation, mortality was higher (OR, 1.38 [1.26-1.52]; P < 0.001). Early intubation was significantly associated with lower mortality (OR, 0.83 [0.72-0.96]), regardless of initial oxygenation strategy. These results persisted after propensity score analysis (matched OR associated with delayed intubation, 1.56 [1.44-1.70]). Conclusions: In immunocompromised intubated patients, survival has improved over time. Time between ICU admission and intubation is a strong predictor of mortality, suggesting a detrimental effect of late initial oxygenation failure.

Preservation of epoxyeicosatrienoic acid bioavailability prevents renal allograft dysfunction and cardiovascular alterations in kidney transplant recipients

This study addressed the hypothesis that epoxyeicosatrienoic acids (EETs) synthesized by CYP450 and catabolized by soluble epoxide hydrolase (sEH) are involved in the maintenance of renal allograft function, either directly or through modulation of cardiovascular function. The impact of single nucleotide polymorphisms (SNPs) in the sEH gene EPHX2 and CYP450 on renal and vascular function, plasma levels of EETs and peripheral blood monuclear cell sEH activity was assessed in 79 kidney transplant recipients explored at least one year after transplantation. Additional experiments in a mouse model mimicking the ischemia–reperfusion (I/R) injury suffered by the transplanted kidney evaluated the cardiovascular and renal effects of the sEH inhibitor t-AUCB administered in drinking water (10 mg/l) during 28 days after surgery. There was a long-term protective effect of the sEH SNP rs6558004, which increased EET plasma levels, on renal allograft function and a deleterious effect of K55R, which increased sEH activity. Surprisingly, the loss-of-function CYP2C9*3 was associated with a better renal function without affecting EET levels. R287Q SNP, which decreased sEH activity, was protective against vascular dysfunction while CYP2C8*3 and 2C9*2 loss-of-function SNP, altered endothelial function by reducing flow-induced EET release. In I/R mice, sEH inhibition reduced kidney lesions, prevented cardiac fibrosis and dysfunction as well as preserved endothelial function. The preservation of EET bioavailability may prevent allograft dysfunction and improve cardiovascular disease in kidney transplant recipients. Inhibition of sEH appears thus as a novel therapeutic option but its impact on other epoxyfatty acids should be carefully evaluated.

Serum creatinine level at 1-month posttransplant can independently predict long-term graft survival and functional status

Background

After the year 2000, kidney transplants with high immunologic risk and deceased donors increased rapidly in Korea. At the same time, the medical community developed special pretransplant and early posttransplantation management protocols. Our team evaluated the effect of early graft stabilization on long-term graft survival and functional status using databases from a high-volume kidney transplantation center.

Methods

We included 1,895 kidney transplant patients from a total of 1,976 performed between 2005 and 2018. Early graft failure within 1 month (n=9), loss to follow-up (n=2), pediatric recipient or donor (n=37), and combined organ transplantation (n=33) cases were excluded. We grouped the cases at 1-month posttransplantation by serum creatinine quantiles (1.0 mg%, 1.23 mg%, and 1.52 mg%).

Results

After an average of 95 months of follow-up (maximum 189 months), the high-serum creatinine group (4th quantile) showed significantly poorer graft survival than other groups (1st to 3rd quantile) (P<0.05). In multiple Cox regression analysis, a high serum creatinine level (4th quantile) at 1-month posttransplant is an independent risk factor for graft failure with a hazard ratio of 1.799 (P=0.013). The quantile group by serum creatinine shows a persistent, significant difference of functional graft status (glomerular filtration rate by Modification of Diet in Renal Disease method) among quantile groups beyond ten years posttransplant.

Conclusions

Serum creatinine level at 1-month posttransplant is a strong independent predictor of graft survival and functional graft status beyond ten years posttransplant.

The risk factors for treatment-related mortality within first three months after kidney transplantation

Mortality at an early stage after kidney transplantation is a disastrous event. Treatment-related mortality (TRM) within 1 or 3 months after kidney transplantation has been rarely reported. We designed a cohort study using the national Korean Network for Organ Sharing database that includes information about kidney recipients between 2002 and 2016. Their demographic, and laboratory data were collected to analyze risk factors of TRM. A total of 19,815 patients who underwent kidney transplantation in any of 40 medical centers were included. The mortality rates 1 month (early TRM) and 3 months (TRM) after transplantation were 1.7% (n = 330) and 4.1% (n = 803), respectively. Based on a multivariate analysis, older age (hazard ratio [HR] = 1.044), deceased donor (HR = 2.210), re-transplantation (HR = 1.675), ABO incompatibility (HR = 1.811), higher glucose (HR = 1.002), and lower albumin (HR = 0.678) were the risk factors for early TRM. Older age (HR = 1.014), deceased donor (HR = 1.642), and hyperglycemia (HR = 1.003) were the common independent risk factors for TRM. In contrast, higher serum glutamic oxaloacetic transaminase (HR = 1.010) was associated with TRM only. The identified risk factors should be considered in patient counselling, and management to prevent TRM. The recipients assigned as the high-risk group require intensive management including glycemic control at the initial stage after transplant.

The risk factors associated with treatment-related mortality in 16,073 kidney transplantation-A nationwide cohort study

Mortality at an early stage after kidney transplantation is a catastrophic event. Treatment-related mortality (TRM) within 1 or 3 months after kidney transplantation has been seldom reported. We designed a retrospective observational cohort study using a national population-based database, which included information about all kidney recipients between 2003 and 2016. A total of 16,073 patients who underwent kidney transplantation were included. The mortality rates 1 month (early TRM) and 3 months (TRM) after transplantation were 0.5% (n = 74) and 1.0% (n = 160), respectively. Based on a multivariate analysis, older age (hazard ratio [HR] = 1.06; P < 0.001), coronary artery disease (HR = 3.02; P = 0.002), and hemodialysis compared with pre-emptive kidney transplantation (HR = 2.53; P = 0.046) were the risk factors for early TRM. Older age (HR = 1.07; P < 0.001), coronary artery disease (HR = 2.88; P < 0.001), and hemodialysis (HR = 2.35; P = 0.004) were the common independent risk factors for TRM. In contrast, cardiac arrhythmia (HR = 1.98; P = 0.027) was associated only with early TRM, and fungal infection (HR = 2.61; P < 0.001), and epoch of transplantation (HR = 0.34; P < 0.001) were the factors associated with only TRM. The identified risk factors should be considered in patient counselling, selection, and management to prevent TRM.

Human umbilical cord mesenchymal stem cell attenuates renal fibrosis via TGF-β/Smad signaling pathways in vivo and in vitro

Renal fibrosis is a progressive pathological process that eventually leads to end-stage renal failure with limited therapeutic options. The aim of this study was to investigate the nephron-protective effect of human umbilical cord mesenchymal stem cells (ucMSCs) on renal fibrosis. UcMSCs were intravenously injected into renal fibrosis mice induced by aristolochic acid (AA) and co-cultured with HK-2 cells induced by TGF-β1, respectively. The kidney functions including serum creatinine (Scr) and blood urea nitrogen (BUN) levels, and histopathology were examined after treated with stem cells and normal saline as control. Immunohistochemical staining, immunofluorescent staining, and Western blot analysis were used to assessed the expression of proteins associated with epithelial to mesenchymal transition (EMT) and TGF-β/Smad signaling pathway. The results showed that ucMSCs effectively improved the kidney function and pathological structure, reduced AA-induced fibrosis and extracellular matrix deposition. Besides, UcMSCs significantly inhibited the EMT process and TGF-β1/Smad signaling pathway in AA-induced mice and TGF-β1-induced HK-2 cells compared to the control (p < 0.05). Our data suggested that ucMSCs play as a nephron-protective role in anti-fibrosis through inhibiting the activation of TGF-β1/Smad signaling pathway.

Frailty predicts surgical complications after kidney transplantation. A propensity score matched study

Background and objective

Surgical complications after kidney transplantation can lead to catastrophic outcomes. Frailty has been associated with important kidney transplantation outcomes; however, there are no studies assessing this measure of physiological reserve as a specific predictor of surgical complications in this population. Such an assessment was, therefore, the objective of the present study.

Methods

A total of 87 individuals aged ≥ 18 years who underwent kidney transplantation between March 2017 and March 2018 were included. At the time of admission for kidney transplantation, demographic, clinical, and kidney transplantation data were collected, and the frailty score was calculated according to Fried et al., which comprises five components: shrinking, weakness, exhaustion, low activity, and slowed walking speed. Urological, vascular, and general surgical complications were assessed three months later, or until graft loss or death. The propensity score was used to achieve a better homogeneity of the sample, and new analyses were performed in this new, balanced sample.

Results

Of the 87 individuals included, 30 (34.5%) had surgical complications. After propensity score matching, the risk of surgical complications was significantly higher among the frail individuals (RR 2.14; 95% CI 1.01–4.54; p = 0.035); specifically, the risk of noninfectious surgical complications was significantly higher among these individuals (RR 2.50; 95% CI 1.11–5.62; p = 0.017).

Conclusion

The results showed that individuals with some degree of frailty before kidney transplantation were more subject to surgical complications. The calculation of the frailty score for transplant candidates and the implementations of measures to increase the physiological reserve of these patients at the time of kidney transplantation may possibly reduce the occurrence of surgical complications.

HLA-G and humanized mouse models as a novel therapeutic approach in transplantation

HLA-G is a nonclassical MHC-Class I molecule whose expression, along the feto-maternal barrier contributes towards tolerance of the semiallogeneic fetus during pregnancy. In light of its inhibitory properties, recent research has established HLA-G involvement in mechanisms responsible for directing allogeneic immune responses towards tolerance during allogeneic situations such as organ transplantation. Here, we critically review the data supporting the tolerogenic role of HLA-G in organ transplantation, the various factors influencing its expression, and the introduction of novel humanized mouse models that are one of the best approaches to assess the utility of HLA-G as a therapeutic tool in organ transplantation.

HLA-G dimer targets Granzyme B pathway to prolong human renal allograft survival

Human leukocyte antigen G (HLA-G), a nonclassic HLA class Ib molecule involved in the maintenance of maternal tolerance to semiallogeneic fetal tissues during pregnancy, has emerged as a potential therapeutic target to control allograft rejection. We demonstrate here that the level of soluble HLA-G dimer was higher in a group of 90 patients with a functioning renal allograft compared with 40 patients who rejected (RJ) their transplants. The HLA-G dimer level was not affected by demographic status. One of the potential mechanisms in tissue-organ allograft rejection involves the induction of granzymes and perforin, which are the main effector molecules expressed by CD8⁺ cytotoxic T lymphocytes and function to destroy allogeneic transplants. Using genomics and molecular and cellular analyses of cells from T-cell-mediated RJ and nonrejected kidney transplant patients, cells from leukocyte Ig-like receptor B1 (LILRB1) transgenic mice, humanized mice, and genetically engineered HLA-G dimer, we demonstrated a novel mechanism by which HLA-G dimer inhibits activation and cytotoxic capabilities of human CD8⁺ T cells. This mechanism implicated the down-regulation of Granzyme B expression and the essential involvement of LILRB1. Thus, HLA-G dimer has the potential to be a specific and effective therapy for prevention of allograft rejection and prolongation of graft survival.-Ajith, A., Portik-Dobos, V., Nguyen-Lefebvre, A. T., Callaway, C., Horuzsko, D. D., Kapoor, R., Zayas, C., Maenaka, K., Mulloy, L. L., Horuzsko, A. HLA-G dimer targets Granzyme B pathway to prolong human renal allograft survival.

Evaluation of the 1000 renal transplants carried out at the University Hospital of the Botucatu Medical School (HCFMB) - UNESP and their evolution over the years

INTRODUCTION

The progress in kidney transplantation has been evident over the years, as well as its benefits for patients.

OBJECTIVES

To evaluate the 1.000 kidney transplants performed at the Botucatu Medical School University Hospital, subdividing the patients in different periods, according to the current immunosuppression, and evaluating the differences in graft and patient survival.

METHODS

Retrospective cohort analysis of the transplants performed between 06/17/87 to 07/31/16, totaling 1,046 transplants, subdivided into four different periods: 1) 1987 to 2000: cyclosporine with azathioprine; 2) 2001 to 2006: cyclosporine with mycophenolate; 3) 2007 to 2014: tacrolimus with antimetabolic; and 4) 2015 to 2016: tacrolimus with antimetabolic, with increased use of the combination of tacrolimus and mTOR inhibitors.

RESULTS

There was an increase in the mean age of recipients and increase in deceased donors and their age in the last two periods. There was a reduction in graft function delay, being 54.3% in the fourth period, compared to 78.8% in the first, p = 0.002. We found a reduction in acute rejection, being 6.1% in the last period compared to 36.3% in the first, p = 0.001. Urological complications and diabetes after transplantation were more frequent in the first two periods. The rates of cytomegalovirus infection were higher in the last two periods. There was an improvement in graft survival, p = 0.003. There was no difference in patient survival, p = 0.77 (Figure 2).

CONCLUSION

There was a significant increase in the number of transplants, with evolution in graft survival, despite the worsening in the profiles of recipients and donors.