Research highlights on kidney transplantation in 2021: Voices from China

Over the past 70 years, kidney transplantation has become not only the most mature but also the highest-success-rate surgery among all organ transplantation surgeries. However, the long-term survival of kidney transplant recipients is still challenged by such key factors as ischemia-reperfusion injury related to kidney transplantation, rejection, chronic renal allograft dysfunction, renal allograft fibrosis, immunosuppressive therapy, infections and others. Relevant fundamental and clinical studies have emerged endlessly. At the same time, the research related to kidney transplantation also becomes a new hot spot accordingly in the context of the normalization of novel coronavirus pneumonia. This article reviewed the cutting-edge hot spots in relation to the fundamental and clinical aspects of kidney transplantation together with relevant new techniques and new visions. The studies included in this article focused on the reports published by Chinese teams that are more applicable to the current situation of kidney transplantation in China, for the purpose of providing new thoughts and strategies for the diagnosis and treatment of kidney transplantation related issues in China.Copyright © 2022 Organ Transplantation. All rights reserved.

COVID pneumonitis, a risk factor for persistent lung allograft dysfunction

Introduction/Aim: There is a paucity of data regarding the impact of COVID-19 on allograft function in lung transplant (LTx) recipients. Method(s): We performed a retrospective cohort study of all living LTx recipients in our service between January 2020 and September 2022. Patients with COVID-19 were identified and baseline characteristics recorded. Pre- and post-COVID-19 spirometry was used to identify persistent decline in allograft function (>=10% of FEV 1 decline at 90 days after infection and failure to return to baseline during the study period). Multivariable logistic regression was performed to identify risk factors associated with persistent allograft decline. Result(s): 128/387 (33%) LTx recipients tested positive to SARS-CoV-2 during the study period. The majority, 125 (97%) during the Omicron waves. In those with COVID-19, the median (IQR) recipient age was 50.6 (22-77) with median time post-transplant of 1522 (17-9842) days. The cohort was of Caucasian ethnicity, 105 (82%), with vaccination rates (98.4%) and 48% female. Chronic lung allograft dysfunction (CLAD) was present at time of infection in 48 (37.5%). Severe disease (oxygen requirement) was present in 40 (31%) patients and 10 (7.8%) died. Recipients were followed for median of 172 days (range 90-339) post infection. Persistent FEV 1 decline occurred in 37 (31.4%). Multivariate analysis showed severe disease was independently associated with an increased risk of persistent FEV 1 decline (OR 5.55 [95% CI 2.28-13.48] p =< 0.001). Non-Caucasian ethnicity (OR 2.83, [95% CI 0.92-8.65], p = 0.07) and the presence of CLAD (OR 2.39, [95% CI 0.94-6.08], p = 0.06), were positively correlated, with weak association. No significant association between recipient age, gender, time post-transplant, early COVID therapy, SARS-CoV-2 variant with persistent FEV 1 decline was seen. Conclusion(s): Persistent decline in lung allograft function is common post COVID-19 infection. Severe disease is strongly associated with this outcome and these patients should be monitored for poor long-term allograft recovery. Further investigation into pathological mechanisms responsible for persistent allograft decline is required.

Two-Hit Kidney Allograft Injury by SARS-CoV-2.

Coronavirus disease 2019 (COVID-19) has been associated with acute kidney injury in kidney transplant recipients by several mechanisms. The authors report a case of acute kidney allograft dysfunction in a 48-year-old patient who presented in the emergency room with anasarca and nephrotic syndrome close after mild COVID-19 and no other clinical condition. Histopathology of the allograft biopsy revealed two distinct and simultaneous kidney lesions, collapsing glomerulopathy and thrombotic microangiopathy. Renal function persistently deteriorated, and definitive dialysis was initiated. After excluding other plausible causes for the findings, this case strengthens the hypothesis that the kidney allograft is also a target of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Invasive fungal infections after respiratory viral infections in lung transplant recipients are associated with lung allograft failure and chronic lung allograft dysfunction within 1 year.

BACKGROUND: Respiratory viral infections (RVI) are associated with chronic lung allograft dysfunction (CLAD) and mortality in lung transplant recipients (LTRs). However, the prevalence and impact of secondary invasive fungal infections (IFIs) post RVIs in LTRs have not been investigated. METHODS: We performed a single center retrospective study including LTRs diagnosed with 5 different respiratory viral pathogens between January 2010 to May 2021 and evaluated their clinical outcomes in 1 year. The risk factors of IFIs were evaluated by logistic regression. The impact of IFIs on CLAD stage progression/death was examined by Cox regression. RESULTS: A total of 202 RVI episodes (50 influenza, 31 severe acute respiratory syndrome coronavirus-2, 30 metapneumovirus, 44 parainfluenza, and 47 respiratory syncytial virus) in 132 patients was included for analysis. Thirty-one episodes (15%) were associated with secondary IFIs, and 27 occurred in LTRs with lower respiratory tract infection (LRTI; 28% from 96 LRTI episodes). Aspergillosis was the most common IFI (80%). LTRs with IFIs had higher disease severity during RVI episodes. In multivariable analysis, RVI with LTRI was associated with IFI (adjusted odds ratio [95% confidence interval (CI)] of 7.85 (2.48-24.9). Secondary IFIs were associated with CLAD stage progression/death after accounting for LRTI, pre-existing CLAD, intensive care unit admission, secondary bacterial pneumonia and underlying lung diseases pre-transplant with adjusted hazard ratio (95%CI) of 2.45 (1.29-4.64). CONCLUSIONS: This cohort demonstrated 15% secondary IFI prevalence in LTRs with RVIs. Importantly, secondary IFIs were associated with CLAD stage progression/death, underscoring the importance of screening for fungal infections in this setting.

Clinical course of SARS-CoV-2 infection and recovery in lung transplant recipients.

BACKGROUND: Reports on outcomes following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in lung transplant recipients remain limited. METHODS: We performed a single-center, observational study of outcomes in lung transplant recipients diagnosed with SARS-CoV-2 between 5/1/2020 and 3/15/2022 that were followed for a median of 123 days. We analyzed changes in spirometry, acute lung allograft dysfunction (ALAD) incidence, hospitalization, mechanical ventilation needs, secondary infection, and survival. RESULTS: In our cohort of 336 patients, 103 developed coronavirus disease (COVID) (27 pre-Delta, 20 Delta, and 56 Omicron-era). Twenty-five patients (24%) required hospitalization and 10 patients ultimately died (10%). Among 85 survivors who completed ambulatory spirometry, COVID-19 did not alter change in forced expiratory volume in 1 s (FEV1 ) or forced vital capacity (FVC) over time compared to the preceding 6 months. The pre-COVID FEV1 change was -0.05 ml/day (IQR -0.50 to 0.60) compared to -0.20 ml/day (IQR -1.40 to 0.70) post-COVID (p = .16). The pre-COVID change in FVC was 0.20 ml/day (IQR -0.60 to 0.70) compared to 0.05 ml/day (IQR -1.00 to 1.10) post-COVID (p = .76). Although the cohort overall had stable lung function, 33 patients (39%) developed ALAD or accelerated chronic lung allograft dysfunction (FEV1 decline >10% from pre-COVID baseline). Nine patients (35%) with ALAD recovered lung function. Within 3 months of acute COVID infection, 18 patients (17%) developed secondary infections, the majority being bacterial pneumonia. Finally, vaccination with at least two doses of mRNA vaccine was not associated with improved outcomes. CONCLUSIONS: This study describes the natural history of SARS-CoV-2 infection in a large cohort of lung transplant recipients. Although one third of patients develop ALAD requiring augmented immunosuppression, infection with SARS-CoV-2 is not associated with worsening lung function.

Interferon-stimulated and metallothionein-expressing macrophages are associated with acute and chronic allograft dysfunction after lung transplantation.

BACKGROUND: Lung transplant recipients experience episodes of immune-mediated acute lung allograft dysfunction (ALAD). ALAD episodes are a risk factor for chronic lung allograft dysfunction (CLAD), the major cause of death after lung transplantation. Our objective was to determine key cellular elements in dysfunctional lung allografts, with a focus on macrophages. METHODS: We have applied single-cell RNA sequencing (scRNAseq) to bronchoalveolar lavage cells from stable and ALAD patients and to cells from explanted CLAD lung tissue. RESULTS: We identified 2 alveolar macrophage (AM) subsets uniquely represented in ALAD. Using pathway analysis and differentially expressed genes, we annotated these as pro-inflammatory interferon-stimulated gene (ISG) and metallothionein-mediated inflammatory (MT) AMs. Functional analysis of an independent set of AMs in vitro revealed that ALAD AMs exhibited a higher expression of CXCL10, a marker of ISG AMs, and increased secretion of pro-inflammatory cytokines compared to AMs from stable patients. Using publicly available bronchoalveolar lavage scRNAseq datasets, we found that ISG and MT AMs are associated with more severe inflammation in COVID-19 patients. Analysis of cells from 4 explanted CLAD lungs revealed similar macrophage populations. Donor and recipient cells were identified using expressed single nucleotide variations. We demonstrated contributions of donor and recipient cells to all AM subsets early post-transplant, with loss of donor-derived cells over time. CONCLUSIONS: Our data reveal extensive heterogeneity among lung macrophages after lung transplantation and indicates that specific sub-populations may be associated with allograft dysfunction, raising the possibility that these cells may represent important therapeutic targets.

Research highlights on kidney transplantation in 2021: voices from China.

Over the past 70 years, kidney transplantation has become not only the most mature but also the highest-success-rate surgery among all organ transplantation surgeries. However, the long-term survival of kidney transplant recipients is still challenged by such key factors as ischemia-reperfusion injury related to kidney transplantation, rejection, chronic renal allograft dysfunction, renal allograft fibrosis, immunosuppressive therapy, infections and others. Relevant fundamental and clinical studies have emerged endlessly. At the same time, the research related to kidney transplantation also becomes a new hot spot accordingly in the context of the normalization of novel coronavirus pneumonia. This article reviewed the cutting-edge hot spots in relation to the fundamental and clinical aspects of kidney transplantation together with relevant new techniques and new visions. The studies included in this article focused on the reports published by Chinese teams that are more applicable to the current situation of kidney transplantation in China, for the purpose of providing new thoughts and strategies for the diagnosis and treatment of kidney transplantation related issues in China. (English) [ FROM AUTHOR] 经过近 70 年的发展，肾移植已成为所有器官移植手术里最成熟，也是成功率最高的手术，但肾移 植相关缺血 - 再灌注损伤、排斥反应、慢性移植肾失功、移植肾纤维化、免疫抑制治疗与感染等仍是影响肾移植 受者长期生存的关键因素，相关的基础与临床研究层出不穷。同时，在新型冠状病毒肺炎疫情常态化的背景下， 与肾移植相关的研究也是一个新的热点。本文就 2021 年肾移植基础与临床相关的前沿热点以及肾移植相关的新 技术、新视野做一综述，且介绍的研究以中国团队发表的报道为主，更符合中国肾移植的实际情况，以期为我国 肾移植相关问题的诊疗提供新的思路和策略. (Chinese) [ FROM AUTHOR] Copyright of Organ Transplantation / Qi Guan Yi Zhi is the property of Organ Transplantation Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)

Characteristics and outcomes among vaccinated lung transplant patients with breakthrough COVID-19.

BACKGROUND: Despite multiple studies evaluating the immunological responsiveness to vaccines, the clinical effectiveness of the two-dose mRNA vaccine schedule among lung transplant (LT) patients has not been evaluated. METHODS: We included LT patients who tested positive for SARS-CoV-2 on a nasopharyngeal swab between March 1, 2020, and August 25, 2021 (n = 70). The study group was divided based on their vaccination status. RESULTS: During the study period, 14 fully vaccinated LT patients with one of the mRNA vaccines tested positive for COVID-19 (median age 54, range 30-62 years, M:F 9:5). The vaccinated cohort was younger with bilateral LT, have suppurative conditions as the transplant indication, and present with milder symptoms. However, pulmonary parenchymal involvement was seen among all 12 patients where computed tomography (CT) of chest was available. The laboratory profile indicated a more subdued inflammatory response among the vaccinated group. A lower proportion of vaccinated patients developed respiratory failure, needed ICU admission or ventilator support, although none of the differences achieved statistical significance. None of the vaccinated patients succumbed to COVID-19 during the study period, while the 4-week mortality among unvaccinated patients was nearly 15% (8/56). CONCLUSIONS: In this cohort of vaccinated LT patients who developed breakthrough COVID-19, the clinical course, risk of complications, and outcomes trended better than unvaccinated patients. However, universal involvement of the allograft demonstrates the continued vulnerability of these patients to significant sequelae from COVID-19. Future studies may evaluate the incremental protection of vaccination after the completion of the third dose of mRNA vaccines among LT patients.

Predictors and outcomes of respiratory failure among lung transplant patients with COVID-19.

BACKGROUND: There is limited data on the predictors and outcomes of new or worsening respiratory failure among lung transplant (LT) patients with Coronavirus disease 2019 (COVID-19). METHODS: We included all the LT patients diagnosed with COVID-19 during a 1-year period (March 2020 to February 2021; n = 54; median age: 60, 20-73 years; M:F 37:17). Development of new or worsening respiratory failure (ARF) was the primary outcome variable. RESULTS: The overall incidence of ARF was 48.1% (n = 26). More than 20% of patients (n = 11) needed intubation and mechanical ventilation. Body mass index > 25 Kg/m2 (adjusted OR: 5.7, .99-32.93; P = .05) and peak D-dimer levels > .95 mcg/ml (adjusted OR: 24.99, 1.77-353.8; P = .017) were independently associated with ARF while anticoagulation use prior to COVID-19 was protective (adjusted OR: .024, .001-.55; P = .02). Majority patients survived the acute illness (85.2%). Pre-infection chronic lung allograft dysfunction (CLAD) was an independent predictor of mortality (adjusted HR: 5.03, 1.14-22.25; P = .033). CONCLUSIONS: COVID-19 is associated with significant morbidity and mortality among LT patients. Patients on chronic anticoagulation seem to enjoy favorable outcomes, while higher BMI and peak D-dimer levels are associated with development of ARF. Pre-infection CLAD is associated with an increased risk of death from COVID-19.

The Year in Cardiothoracic Transplant Anesthesia: Selected Highlights From 2020 Part I - Lung Transplantation.

This special article focuses on the highlights in cardiothoracic transplantation literature in the year 2020. Part I encompasses the recent literature on lung transplantation, including the advances in preoperative assessment and optimization, donor management, including the use of ex-vivo lung perfusion, recipient management, including those who have been infected with coronavirus disease 2019, updates on the perioperative management, including the use of extracorporeal membrane oxygenation, and long-term outcomes.

Post-infection pulmonary sequelae after COVID-19 among patients with lung transplantation.

BACKGROUND: There is limited data on outcomes among lung transplant (LT) patients who survive Coronavirus disease 2019 (COVID-19). METHODS: Any single or bilateral LT patients who tested positive for SARS-CoV-2 between March 1, 2020, to February 15, 2021 (n = 54) and survived the acute illness were included (final n = 44). Each patient completed at least 3 months of follow-up (median: 4.5; range 3-12 months) after their index hospitalization for COVID-19. The primary endpoint was a significant loss of lung functions (defined as > 10% decline in forced vital capacity (FVC) or forced expiratory volume in 1 s (FEV1 ) on two spirometries, at least 3 weeks apart compared to the pre-infection baseline). RESULTS: A majority of the COVID-19 survivors had persistent parenchymal opacities (n = 29, 65.9%) on post-infection CT chest. Patients had significantly impaired functional status, with the majority reporting residual disabilities (Karnofsky performance scale score of 70% or worse; n = 32, 72.7%). A significant loss of lung function was observed among 18 patients (40.9%). Three patients met the criteria for new chronic lung allograft dysfunction (CLAD) following COVID-19 (5.6%), with all three demonstrating restrictive allograft syndrome phenotype. An absolute lymphocyte count < 0.6 × 103 /dl and ferritin > 150 ng/ml at the time of hospital discharge was independently associated with significant lung function loss. CONCLUSIONS: A significant proportion of COVID-19 survivors suffer persistent allograft injury. Low absolute lymphocyte counts (ALC) and elevated ferritin levels at the conclusion of the hospital course may provide useful prognostic information and form the basis of a customized strategy for ongoing monitoring and management of allograft dysfunction. TWEET: Twitter handle: @AmitBangaMD Lung transplant patients who survive COVID-19 suffer significant morbidity with persistent pulmonary opacities, loss of lung functions, and functional deficits. Residual elevation of the inflammatory markers is predictive.

Viral infections in lung transplantation.

Viral infections account for up to 30% of all infectious complications in lung transplant recipients, remaining a significant cause of morbidity and even mortality. Impact of viral infections is not only due to the direct effects of viral replication, but also to immunologically-mediated lung injury that may lead to acute rejection and chronic lung allograft dysfunction. This has particularly been seen in infections caused by herpesviruses and respiratory viruses. The implementation of universal preventive measures against cytomegalovirus (CMV) and influenza (by means of antiviral prophylaxis and vaccination, respectively) and administration of early antiviral treatment have reduced the burden of these diseases and potentially their role in affecting allograft outcomes. New antivirals against CMV for prophylaxis and for treatment of antiviral-resistant CMV infection are currently being evaluated in transplant recipients, and may continue to improve the management of CMV in lung transplant recipients. However, new therapeutic and preventive strategies are highly needed for other viruses such as respiratory syncytial virus (RSV) or parainfluenza virus (PIV), including new antivirals and vaccines. This is particularly important in the advent of the COVID-19 pandemic, for which several unanswered questions remain, in particular on the best antiviral and immunomodulatory regimen for decreasing mortality specifically in lung transplant recipients. In conclusion, the appropriate management of viral complications after transplantation remain an essential step to continue improving survival and quality of life of lung transplant recipients.

Clinical characteristics, management practices, and outcomes among lung transplant patients with COVID-19.

BACKGROUND: There are limited data on management strategies and outcomes among lung transplant (LT) patients with Coronavirus disease 2019 (COVID-19). We implemented management protocols based on the best available evidence and consensus among multidisciplinary teams. The current study reports our experience and outcomes using this protocol-based management strategy. METHODS: We included single or bilateral LT patients who tested positive for SARS-CoV-2 on nasopharyngeal swab between March 1, 2020, to December 15, 2020 (n = 25; median age: 60, range 20-73 years; M: F 17:8). A group of patients with Respiratory Syncytial Virus (RSV) infection during 2016-18 were included to serve as a comparator group (n = 36). RESULTS: As compared to RSV, patients with COVID-19 were more likely to present with constitutional symptoms, spirometric decline, pulmonary opacities, new or worsening respiratory failure, and need for ventilator support. Patients with SARS-CoV-2 infection were less likely to receive a multimodality treatment strategy, and they experienced worse post-infection lung function loss, functional decline, and three-month survival. A significant proportion of patients with COVID-19 needed readmission for worsening allograft function (36.4%), and chronic kidney disease at initial presentation was associated with this complication. Lower pre-morbid FEV1 appeared to increase the risk of new or worsening respiratory failure, which was associated with worse outcomes. Overall hospital survival was 88% (n = 22). Follow-up data was available for all discharged patients (median: 43.5 days, range 15-287 days). A majority had persistent radiological opacities (19/22, 86.4%), with nearly half of the patients with available post-COVID-19 spirometry showing > 10% loss in lung function (6/13, median loss: 14.5%, range 10%-31%). CONCLUSIONS: Despite similar demographic characteristics and predispositions, LT patients with COVID-19 are sicker and experience worse outcomes as compared to RSV. Despite the availability of newer therapeutic agents, COVID-19 continues to be associated with significant morbidity and mortality.

COVID-19 in a lung transplant recipient: Exploring the diagnostic role of circulating exosomes and the clinical impact of advanced immunosuppression.

Exosomes isolated from plasma of lung transplant recipients with allograft injury contain donor-derived lung self-antigens (collagen V and Kα1 tubulin) and human leukocyte antigen (HLA) molecules. We present a case of a 76-year-old, female lung transplant recipient treated for acute cellular rejection with methylprednisolone and anti-thymocyte globulin, who subsequently contracted SARS-CoV-2 and developed a sharp increase in the mean fluorescent intensity of anti-HLA antibodies. Analysis of circulating exosomes during rejection, but before SARS-CoV-2 infection, revealed the presence of lung self-antigens and HLA class II molecules. After the patient contracted SARS-CoV-2, exosomes with the SARS-CoV-2 spike protein were also found. After resolution of infectious symptoms, exosomes with SARS-CoV-2 spike protein were no longer detected; however, exosomes with lung self-antigens and HLA class II molecules persisted, which coincided with a progressive decline in spirometric flows, suggesting chronic lung allograft dysfunction. We propose that the analysis of circulating exosomes may be used to detect allograft injury mediated by both rejection and infection. Furthermore, the detection of exosomes containing viral proteins may be helpful in identifying allograft injury driven by viral pathogens.