Histological spectrum of pulmonary manifestations in kidney transplant recipients on sirolimus inclusive immunosuppressive regimens

Assessment of respiratory function in children after kidney transplantation

BACKGROUND

Severe respiratory complications following kidney transplantation have been reported, yet remain poorly understood in the pediatric population. This study aimed to document respiratory disease in this population.

METHODS

At annual follow-ups, patients completed a respiratory symptoms questionnaire and underwent pulmonary function tests (PFTs). We defined respiratory disease in children when they had clinical disorders and/or PFT abnormalities.

RESULTS

Among 236 children included, 110 (41%) exhibited respiratory involvement: 59 (53%) had only clinical disorders, 38 (35%) had only PFT abnormalities, and 13 (12%) had both. Of those with PFT abnormalities, 15 (7%) had obstructive impairment, 12 (6%) had restrictive impairment, and 30 (24%) showed decreased lung diffusion capacity for carbon monoxide (DLCO)/transfer coefficient for carbon monoxide (KCO). In the multivariate analysis, being over 3.5 years of age at the time of transplantation was associated with a reduced risk of respiratory involvement (OR 0.30, CI [0.14; 0.63], p = 0.002), such as induction with basiliximab (OR 0.39, CI [0.17; 0.90], p = 0.03). Conversely, history of immune deficiency, male gender, positive PCR for BK virus and diastolic hypertension were associated with an increased risk (OR 5.96, CI [2.15; 16.51], p = 0.0006, OR 1.97, CI [1.03; 3.77], p = 0.04, OR 3.77, CI [1.14; 12.52], p = 0.03 and OR 2.21, CI [1.13; 4.32], p = 0.02, respectively). Bronchial lesions, such as bronchiectasis, were predominantly observed on tomography.

CONCLUSIONS

Given the risk of irreversible lung damage, we recommend systematic clinical and functional respiratory monitoring in case of respiratory symptoms, recurrent lower respiratory tract infections, and risk factors in their follow-up.

Long-term respiratory outcomes following solid organ transplantation in children: A retrospective cohort study

BACKGROUND

Solid-organ transplantation (SOT) has become commonly used in children and is associated with excellent survival rates into adulthood. Data regarding long-term respiratory outcomes following pediatric transplantation are lacking. We aimed to describe the prevalence and nature of respiratory pathology following pediatric heart, kidney, and liver transplant, and identify potential risk factors for respiratory complications.

METHODS

Retrospective review involving all children under active follow-up at the provincial transplant service in British Columbia, Canada, following SOT.

RESULTS

Of 118 children, 33% experienced respiratory complications, increasing to 54% in heart transplant recipients. Chronic or recurrent cough with persistent chest x-ray changes was the most common clinical picture, and most infections were with nonopportunistic organisms typically found in otherwise healthy children. A history of respiratory illness before transplant was significantly associated with risk of posttransplant respiratory complications. Eight percentage8% were diagnosed with bronchiectasis, which was more common in recipients of heart and kidney transplant. Bronchiectasis was associated with recurrent hospital admissions with lower respiratory tract infections, treatment of acute rejection episodes, and treatment with sirolimus.

INTERPRETATION

Respiratory morbidity is common after pediatric SOT, and bronchiectasis rates were disproportionately high in this patient group. We hypothesize that this relates to recurrent infections resulting from iatrogenic immunosuppression. Direct pulmonary toxicity from immunosuppression drugs may also be contributory. A high index of suspicion for respiratory complications is needed following childhood SOT, particularly in those with a history of respiratory disease before transplant, experiencing recurrent or severe respiratory tract infections, or exposed to intensified immunosuppression.

Bronchoscopic Lobar Lavage in the Treatment of a Single Lung Transplant Recipient With Pulmonary Alveolar Proteinosis: A Case Report

Pulmonary alveolar proteinosis is a rare disorder that results from impaired clearance of surfactant. There are few case reports in lung transplant recipients. We report the case of a 57-year-old man with chronic hypersensitivity pneumonitis who underwent left single lung transplantation. Approximately 1 year after transplant, he was diagnosed as having pulmonary alveolar proteinosis by surgical lung biopsy. He was successfully treated with bronchoscopic lobar lavage of his allograft but later was diagnosed as having peritoneal mesothelioma. We highlight the challenges in the diagnosis, discuss potential etiologies, and describe a unique therapy of this rare disorder in lung transplant recipients.

mTOR-Inhibition and COVID-19 in Kidney Transplant Recipients: Focus on Pulmonary Fibrosis

Kidney transplant recipients are at high risk of developing severe COVID-19 due to the coexistence of several transplant-related comorbidities (e.g., cardiovascular disease, diabetes) and chronic immunosuppression. As a consequence, a large part of SARS-CoV-2 infected patients have been managed with a reduction of immunosuppression. The mTOR-I, together with antimetabolites, have been often discontinued in order to minimize the risk of pulmonary toxicity and to antagonize pharmacological interaction with antiviral/anti-inflammatory drugs. However, at our opinion, this therapeutic strategy, although justified in kidney transplant recipients with severe COVID-19, should be carefully evaluated in asymptomatic/paucisymptomatic patients in order to avoid the onset of acute allograft rejections, to potentially exploit the mTOR-I antiviral properties, to reduce proliferation of conventional T lymphocytes (which could mitigate the cytokine storm) and to preserve Treg growth/activity which could reduce the risk of progression to severe disease. In this review, we discuss the current literature regarding the therapeutic potential of mTOR-Is in kidney transplant recipients with COVID-19 with a focus on pulmonary fibrosis.

Reversible sirolimus-induced pulmonary alveolar proteinosis in a renal transplant patient

Pulmonary alveolar proteinosis (PAP) is characterized by accumulation of surfactant-like lipoprotein material within distal bronchioles and alveoli due to impaired clearance. Clinically, PAP presents with dyspnea and cough. A 58-year-old Hispanic man presented with 6 months of productive cough, weight loss, and progressively worsening dyspnea. He reported a long history of poorly controlled type 2 diabetes that led to diabetic nephropathy. The patient had a strong passive smoking history for over 30 years and exposure to woodsmoke. He had pulmonary tuberculosis in 2007 and 2012. In 2011, he was diagnosed with renal failure, was dialyzed for a year, and received a renal transplant in 2012. His posttransplant medication regimens included tacrolimus, mycophenolic acid, and prednisone. Six months after the transplant, he suffered graft rejection, managed with steroids and switching from tacrolimus to sirolimus. His physical examination demonstrated scattered inspiratory crackles, and a chest X-ray showed bilateral perihilar ground-glass opacities. PAP was diagnosed through lung biopsy, which showed eosinophilic granular infiltrate withing the alveoli. Sirolimus was switched back to tacrolimus 2 mg in September 2018. PAP diagnosis included hematoxylin and eosin and PAS. Clinical follow-up included oxygen saturation with pulse oximeter and chest X-rays. A 2-month follow-up showed only partial improvement in both symptoms and radiological findings. In January 2019, a follow-up showed complete radiological and symptomatologic resolution. After 5 months, the patient remains asymptomatic with adequate exertion tolerance. PAP remains a diagnosis of exclusion in patients undergoing immunomodulatory therapy with sirolimus and pulmonary symptoms. Reversal can be achieved by switching agents.

Pulmonary Complications After Solid Organ Transplantation: An Autopsy Perspective

Pulmonary complications following solid organ transplantation are common and often infectious in nature. Articles describing noninfectious pulmonary complications overwhelmingly rely on clinical and radiographic data. There are a limited number of studies with companion histology delineating the clinical diagnoses of pulmonary complications. This contrasts with blood and bone marrow transplantations. Using a retrospective cohort approach, the current study aimed to assess antemortem and postmortem pulmonary findings in solid organ transplantation recipients. Medical records and autopsy materials from 92 solid organ transplantation recipients were reviewed. Pulmonary complications were identified in 70 patients (76%). For patients with pulmonary complications at autopsy the mean survival posttransplantation was 3.48 years as compared to 7.29 years for patients without pulmonary complications at autopsy (P = .01). Twenty-eight infectious complications (fungal pneumonia, n = 20; cytomegalovirus pneumonia, n = 7; bacterial pneumonia, n = 1) and 113 noninfectious pulmonary complications were identified. The most common noninfectious findings were diffuse alveolar damage (n = 32), organizing pneumonia (n = 31), and pulmonary thromboemboli (n = 26). Disseminated infections and respiratory failure were the most common immediate causes of death (n = 24 and n = 23, respectively). Most noninfectious complications were not diagnosed antemortem.

Sirolimus-Induced Diffuse Alveolar Hemorrhage: A Case Report

Sirolimus is a mammalian target of the rapamycin, a protein kinase, which is responsible for inhibition of T cell and B cell proliferation. Sirolimus has side effects on lugs, and may cause cryptogenic organizing pneumonia, diffuse alveolar hemorrhage, lymphocytic pneumonitis, hypersensitivity pneumonitis, desquamative interstitial pneumonia, and pulmonary alveolar proteinosis. Diagnosis is based on the combination of clinical, radiological, histological, and pathological investigation. We report a case of diffuse alveolar hemorrhage in a 33-year-old, female renal transplant recipient. After discontinuation of sirolimus, radiological images and clinical condition of the patient got better. We also planned steroid therapy for 6 months by tapering the dosage slowly. After steroid therapy, full recovery of pulmonary functions achieved, and the patient is observed in our outpatient clinic with lack of any pulmonary symptoms.

The diagnostic yield and complications of open lung biopsies in kidney transplant patients with pulmonary disease

BACKGROUND

The purpose of this study was to assess the efficacy of open lung biopsy (OLB) in determining the specific diagnosis and the related complications in patients with undiagnosed diffuse pulmonary infiltrates.

METHODS

This single center, retrospective study included adult kidney transplant patients who underwent OLB. The patients had diffuse pulmonary infiltrates without definitive diagnoses and failed to respond to empiric antibiotic treatment. We analyzed the number of specific diagnoses, changes in treatment and the occurrence of complications in these patients. A logistic regression was used to determine which variables were predictors of hospital mortality.

RESULTS

From April 2010 to April 2014, 87 patients consecutively underwent OLB. A specific diagnosis was reached in 74 (85.1%) patients. In 46 patients (53%), their therapeutic management was changed after the OLB results. Twenty-five (28.7%) patients had complications related to the OLB. The hospital mortality rate was 25.2%. Age, SAPS3 score and complications related to the procedure were independent predictors of all-cause mortality.

CONCLUSIONS

OLB is a high-risk procedure with a high diagnostic yield in kidney transplant patients with diffuse pulmonary infiltrates who did not have a definitive diagnosis and who failed to respond to empiric antibiotic treatment. Complications related to OLB were common and were independently associated with intra-hospital mortality.

Lung Transplant Recipient with Pulmonary Alveolar Proteinosis

Pulmonary alveolar proteinosis (PAP) is a progressive lung disease characterized by accumulated surfactant-like lipoproteinaceous material in the alveoli and distal bronchioles. This accumulation is the result of impaired clearance by alveolar macrophages. PAP has been described in 11 solid organ transplant recipients, 9 of whom were treated with mammalian target of rapamycin inhibitors. We report a case of a lung transplant recipient treated with prednisone, mycophenolate mofetil (MMF), and tacrolimus who ultimately developed PAP, which worsened when MMF was replaced with everolimus.

Safety of mTOR inhibitors in adult solid organ transplantation

INTRODUCTION

Mammalian target of rapamycin (mTOR) inhibitors (sirolimus and everolimus) are a class of immunosuppressive drugs approved for solid organ transplantation (SOT). By inhibiting the ubiquitous mTOR pathway, they present a peculiar safety profile. The increased incidence of serious adverse events in early studies halted the enthusiasm as a kidney sparing alternative to calcineurin inhibitors (CNI).

AREAS COVERED

Herein we review mTOR inhibitors safety profile for adult organ transplantation, ranging from acute side effects, such as lymphoceles, delayed wound healing, or cytopenias, to long-term ones which increase morbidity and mortality, such as cancer risk and metabolic profile. Infection, proteinuria, and cutaneous safety profiles are also addressed.

EXPERT OPINION

In the authors' opinion, mTOR inhibitors are a safe alternative to standard immunosuppression therapy with CNI and mycophenolate/azathioprine. Mild adverse events can be easily managed with an increased awareness and close monitoring of trough levels. Most serious side effects are dose- and organ-dependent. In kidney and heart transplantation mTOR inhibitors may be safely used as either low-dose de novo or through early-conversion. In the liver, conversion 4 weeks post-transplantation may reduce long-term chronic kidney disease secondary to calcineurin nephrotoxicity, without increasing hepatic artery/portal vein thrombosis.

Interstitial Lung Disease Associated with mTOR Inhibitors in Solid Organ Transplant Recipients: Results from a Large Phase III Clinical Trial Program of Everolimus and Review of the Literature

Interstitial lung disease (ILD) has been reported with the use of mammalian target of rapamycin inhibitors (mTORi). The clinical and safety databases of three Phase III trials of everolimus in de novo kidney (A2309), heart (A2310), and liver (H2304) transplant recipients (TxR) were searched using a standardized MedDRA query (SMQ) search for ILD followed by a case-by-case medical evaluation. A literature search was conducted in MEDLINE and EMBASE. Out of the 1,473 de novo TxR receiving everolimus in Phase III trials, everolimus-related ILD was confirmed in six cases (one kidney, four heart, and one liver TxR) representing an incidence of 0.4%. Everolimus was discontinued in three of the four heart TxR, resulting in ILD improvement or resolution. Outcome was fatal in the kidney TxR (in whom everolimus therapy was continued) and in the liver TxR despite everolimus discontinuation. The literature review identified 57 publications on ILD in solid organ TxR receiving everolimus or sirolimus. ILD presented months or years after mTORi initiation and symptoms were nonspecific and insidious. The event was more frequent in patients with a late switch to mTORi. In most cases, ILD was reversed after prompt mTORi discontinuation. ILD induced by mTORi is an uncommon and potentially fatal event warranting early recognition and drug discontinuation.

mTOR inhibitors and renal allograft: Yin and Yang

Mammalian target of rapamycin inhibitors (mTOR-I), everolimus and sirolimus, are immunosuppressive drugs extensively used in renal transplantation. Their main mechanism of action is the inhibition of cell signaling through the PI3 K/Akt/mTOR pathway. This interesting mechanism of action confers to these medications both great immunosuppressive potential and important anti-neoplastic properties. Although the clinical utility of this drug category, as with other antineoplastic/immunosuppressants, is clear, the use of mTOR-I commonly results in the development of several complications. In particular, these agents may determine severe renal toxicity that, as recent studies report, seems clearly correlated to dose and duration of drug use. The mTOR-I-induced renal allograft spectrum of toxicity includes the enhanced incidence of delayed graft function, nephrotoxicity in particular when co-administered with calcineurin inhibitors (CNI) and onset of proteinuria. The latter effect appears highly frequent in patients undergoing mTOR-I treatment and significantly associated with a rapid graft lost. The damage leading to this complication interests both the glomerular and tubular area. mTOR-I cause an inhibition of proliferation in podocytes and the epithelial-to-mesenchymal transition in tubular cells. Interestingly, all these side effects are mostly reversible and dose related. Therefore, it is unquestionable that these particular drugs should be administered at the lowest dose able to maintain relatively low trough levels, in order to maximize their important and specific therapeutic effects while minimizing or avoiding drug toxicities. Utilization of low dosages of mTOR-I should be encouraged not only in CNI-combined schemas, but also when administered alone in a CNI-free immunosuppressive protocol.

T cell immunohistochemistry refines lung transplant acute rejection diagnosis and grading

Objective

Lung transplant volume has been increasing. However, inaccurate and uncertain diagnosis for lung transplant rejection hurdles long-term outcome due to, in part, interobserver variability in rejection grading. Therefore, a more reliable method to facilitate diagnosing and grading rejection is warranted.

Method

Rat lung grafts were harvested on day 3, 7, 14 and 28 post transplant for histological and immunohistochemical assessment. No immunosuppressive treatment was administered. We explored the value of interstitial T lymphocytes quantification by immunohistochemistry and compared the role of T cell immunohistochemistry with H&E staining in diagnosing and grading lung transplant rejection.

Results

Typical acute rejection from grade A1 to A4 was found. Rejection severity was heterogeneously distributed in one-third transplanted lungs (14/40): lesions in apex and center were more augmented than in the base and periphery of the grafts, respectively. Immunohistochemistry showed profound difference in T lymphocyte infiltration among grade A1 to A4 rejections. The coincidence rate of H&E and immunohistochemistry was 77.5%. The amount of interstitial T lymphocyte infiltration increased gradually with the upgrading of rejection. The statistical analysis demonstrated that the difference in the amount of interstitial T lymphocytes between grade A2 and A3 was not obvious. However, T lymphocytes in lung tissue of grade A4 were significantly more abundant than in other grades.

Conclusions

Rejection severity was heterogeneously distributed within lung grafts. Immunohistochemistry improves the sensitivity and specificity of rejection diagnosis, and interstitial T lymphocyte quantitation has potential value in diagnosing and monitoring lung allograft rejection.

Virtual slides

The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1536075282108217.

Systemic and nonrenal adverse effects occurring in renal transplant patients treated with mTOR inhibitors

The mammalian target of rapamycin inhibitors (mTOR-I), sirolimus and everolimus, are immunosuppressive drugs largely used in renal transplantation. The main mechanism of action of these drugs is the inhibition of the mammalian target of rapamycin (mTOR), a regulatory protein kinase involved in lymphocyte proliferation. Additionally, the inhibition of the crosstalk among mTORC1, mTORC2, and PI3K confers the antineoplastic activities of these drugs. Because of their specific pharmacological characteristics and their relative lack of nephrotoxicity, these inhibitors are valid option to calcineurine inhibitors (CNIs) for maintenance immunosuppression in renal transplant recipients with chronic allograft nephropathy. However, as other immunosuppressive drugs, mTOR-I may induce the development of several adverse effects that need to be early recognized and treated to avoid severe illness in renal transplant patients. In particular, mTOR-I may induce systemic nonnephrological side effects including pulmonary toxicity, hematological disorders, dysmetabolism, lymphedema, stomatitis, cutaneous adverse effects, and fertility/gonadic toxicity. Although most of the adverse effects are dose related, it is extremely important for clinicians to early recognize them in order to reduce dosage or discontinue mTOR-I treatment avoiding the onset and development of severe clinical complications.

Usual interstitial pneumonia coexisted with nonspecific interstitial pneumonia, What's the diagnosis?

The differential diagnosis between idiopathic nonspecific interstitial pneumonia(INSIP) and idiopathic pulmonary fibrosis(IPF)/usual interstitial pneumonia(UIP)is tough in both clinicians and pathologists. In this study, we analyzed the lesions of right lung removed from a 58-year-old patient by gross and microscopy. The results showed that the pathological appearance of nonspecific interstitial pneumonia (NSIP) and UIP coexisted in his upper lobe. Besides, because of severe fibrosis in middle and lower lobes, it was hard to distinguish the lesions of NSIP fibrotic pattern (NSIP-F) or UIP. Based on clinic-radiologic-pathological data, the diagnosis of INSIP-F was made for this patient finally. Our study suggests that UIP is not always an accurate diagnosis when the NSIP and UIP coexist, and NSIP can have regions of UIP.