Clinical predictors of autoimmune and severe atopic disease in pediatric heart transplant recipients

T cell phenotype in paediatric heart transplant recipients

Paediatric heart transplantation recipients suffer an increased incidence of infectious, autoimmune and allergic problems. The relative roles of thymus excision and immunosuppressive treatments in contributing to these sequelae are not clear. We compared the immunological phenotypes of 25 heart transplant recipients (Tx), 10 children who underwent thymus excision during non-transplantation cardiac surgery (TE) and 25 age range-matched controls, in two age bands: 1-9 and 10-16 years. Significant differences from controls were seen mainly in the younger age band with Tx showing lower CD3 and CD4 cell counts whilst TE showed lower CD8 cell counts. Naïve T cell and recent thymic emigrant proportions and counts were significantly lower than controls in both groups in the lower age band. T cell recombination excision circle (TREC) levels were lower than controls in both groups in both age bands. There were no differences in regulatory T cells, but in those undergoing thymus excision in infancy, their proportions were higher in TE than Tx, a possible direct effect of immunosuppression. T cell receptor V beta spectratyping showed fewer peaks in both groups than in controls (predominantly in the older age band). Thymus excision in infancy was associated with lower CD8 cell counts and higher proportions of Tregs in TE compared to Tx. These data are consistent with thymus excision, particularly in infancy, being the most important influence on immunological phenotype after heart transplantation.

Disease Course and Treatment Response of Eosinophilic Gastrointestinal Diseases in Children With Liver Transplantation: Long-Term Follow-Up

INTRODUCTION

To describe the clinical and laboratory profile, natural course, treatment outcome, and risk factors of posttransplant esophageal and nonesophageal eosinophilic gastrointestinal disorders (EGIDs).

METHODS

All children (aged <18 years) who underwent liver transplantation, between 2011 and 2019, in a single transplant center with a follow-up period of 1 year or more posttransplant and with a history of posttransplant endoscopic evaluation were included in this study.

RESULTS

During the study period, 89 children met the inclusion criteria. Patients were followed for a median of 8.0 years. A total of 39 (44%) patients were diagnosed with EGID after transplantation. Of these, 29 (33%) had eosinophilic esophagitis (EoE), and 10 (11%) had eosinophilic gastritis, gastroenteritis or enterocolitis. In comparison with the non-EGID group, patients with EGID were younger at transplant (P ≤ 0.0001), transplanted more frequently due to biliary atresia (P ≤ 0.0001), and had higher rates of pretransplant allergy (P = 0.019). In the posttransplant period, they had higher rates of mammalian Target of Rapamycin inhibitor use (P = 0.006), Epstein-Barr virus viremia (P = 0.03), post-transplant lymphoproliferative disease (P = 0.005), and allergen sensitization (P ≤ 0.0001). In regression analysis, young age at transplant, age at diagnosis, pretransplant atopic dermatitis, and post-transplant lymphoproliferative disease were associated with an increased risk of EGID or EoE. Laboratory abnormalities such as anemia (P = 0.007), thrombocytosis (P = 0.012), and hypoalbuminemia (P = 0.031) were more commonly observed in the eosinophilic gastritis, gastroenteritis or enterocolitis group than in the EoE group. Following treatment, most patients had symptomatic resolution at 3 months and histologic resolution at 6 months postdiagnosis. Among the patients who had 5 years of follow-up, none recurred.

DISCUSSION

EGID is a common posttransplant diagnosis, which seems to affect patients who are transplanted earlier and who have pretransplant atopy. Posttransplant EGID is responsive to treatment, but as histologic remission occurs after symptomatic resolution, the decision to perform control endoscopy should be delayed.

Persistent hypogammaglobulinemia in pediatric solid organ transplant recipients

INTRODUCTION

Hypogammaglobulinemia has not been well studied in pediatric solid organ transplant (SOT) recipients. We evaluated plasma immunoglobulin (Ig) and lymphocyte phenotypes among 31 pediatric heart and kidney recipients for two years post-transplant and from 10 non-transplanted children.

METHODS

Plasma IgM, IgG, and IgA were quantified by immunoturbidimetric assays, IgG subclasses were quantified by bead-based multiplex immunoassay, and lymphocyte phenotypes were assessed by flow cytometry.

RESULTS

Median age at transplant for SOT recipients was similar to that of the control cohort (15 vs. 12.5 years, respectively; P = .61). Mean plasma IgG and IgM levels for SOT recipients fell significantly below the control cohort means by 1 month post-transplant (P < .001 for both) and remained lower than control levels at 12-18 months post-transplant. Heart recipients had lower frequencies of a CD4⁺ naïve T lymphocytes relative to kidney recipients.

CONCLUSIONS

Hypogammaglobulinemia was prevalent and persistent among pediatric SOT recipients and may be secondary to immunosuppressive medications, as well as loss of thymus tissue and CD45RA⁺   CD4⁺ T cells in heart recipients. Limitations of our study include but are not limited to small sample size from a single center, lack of samples for all participants at every time point, and lack of peripheral blood mononuclear cell samples for the non-transplanted cohort.

Immune dysregulation and Th2 polarization are associated with atopic dermatitis in heart-transplant children: A delicate balance between risk of rejection or atopic symptoms

Atopic dermatitis (AD) has a high incidence in heart-transplant children, and the reason why there is more AD after transplantation is still unknown. We conducted a cross-sectional study comparing 11 AD and 11 non-AD age-matched heart-transplant children, to assess which immune alterations are related to AD in these patients. AD patients had been transplanted at a younger age compared to non-AD, indicating that age at transplant may be determinant in the onset of AD. The earlier thymectomy in AD heart-transplant children favored the presence of more differentiated phenotypes in the T cell compartment. We observed a clear reduction in the T-helper 1/T-helper 2 (Th1/Th2) ratio in AD children. This Th2 polarization was related to eosinophilia and high immunoglobulin E levels, but also to an impaired regulatory T cell (Treg) suppression, which could be secondary to an exhaustion of the Treg compartment. Interestingly, AD patients were free of rejection episodes (0/11) in comparison to non-AD children (4/11). We propose that a predominant Th2 phenotype may prevent the emergence of Th1 responses associated with graft rejection. A more differentiated Treg phenotype could also play a role in preventing acute rejection in the first year posttransplant. Our findings provide useful insights and knowledge for the better understanding of atopic disorders in transplanted children.

Characteristics and Outcomes of Heart Transplantation in DiGeorge Syndrome

DiGeorge syndrome (DGS) is commonly associated with both congenital heart disease (CHD) and immunologic abnormalities. While CHD may prompt consideration for heart transplantation (HTx), little is known about HTx management or outcomes in this group. The aim of this study was to describe the spectrum of patients with DGS who undergo HTx and report post-HTx outcomes. All pediatric HTx recipients (2002-2016) with DGS were identified using ICD codes from a linked billing and clinical registry database. Patient characteristics and outcomes were described and compared to non-DGS HTx recipients with CHD. Kaplan-Meier methods were used to assess overall survival, freedom from infection, and freedom from rejection. A total of 17 patients with DGS who underwent HTx at 12 different centers were included. Median age at HTx was 5 years (IQR 0-13 years). Steroids were used for induction in all patients in addition to thymoglobulin in 13/17 (76%) and IL2R antagonists in 3/17 (18%). Maintenance immunosuppression was a combination of tacrolimus or cyclosporine and mycophenolate or azathioprine in 16/17 (94%). Half received steroids at the time of discharge. There were six deaths (35%). The median post-HTx survival was 5.4 years with no difference in freedom from rejection, infection, or overall survival between patients with and without DGS. Patients with DGS undergoing HTx received standard immunosuppression. We found no difference in freedom from infection, rejection, or overall post-HTx survival compared to non-DGS patients, although the small size of our study resulted in limited statistical power. Given the potential for favorable outcomes, patients with DGS may be considered for HTx in the appropriate clinical setting.

Recurrent oral ulcerations following heart transplant in a pediatric patient: A diagnostic dilemma

Oral ulceration is a non-specific clinical finding with many potential causes. The persistence of oral ulcers in the context of a patient post-SOT is concerning for PTLD. There is growing evidence that SOT recipients may also be at higher risk of autoimmune diseases. This case report describes a pediatric patient with persistent oral ulcers after heart transplant, who underwent an extensive workup for PTLD, including repeat investigations, with a subsequent diagnosis of Behçet's disease.

De Novo Allergy and Immune-Mediated Disorders Following Solid-Organ Transplantation-Prevalence, Natural History, and Risk Factors

OBJECTIVES

To describe the prevalence, natural course, outcome, and risk factors of post-transplant de novo allergy and autoimmunity.

STUDY DESIGN

A cross-sectional, cohort study of all children (<18 years) who underwent a solid-organ transplantation, between 2000 and 2012, in a single transplant center, with a follow-up period of 6 months or more post-transplant and without history of allergy or immune-mediated disorder pretransplant.

RESULTS

A total of 626 eligible patients were screened, and 273 patients (160 males; 59%) met the inclusion criteria; this included 111 liver, 103 heart, 52 kidney, and 7 multivisceral recipients. Patients were followed for a median period of 3.6 years. A total of 92 (34%) patients (42 males, 46%) developed allergy or autoimmune disease after transplantation, with a high prevalence among liver (41%), heart (40%), and multivisceral (57%) transplant recipients compared with kidney recipients (4%; P < .001). Post-transplant allergies included eczema (n = 44), food allergy (22), eosinophilic gastrointestinal disease (11), and asthma (28). Autoimmunity occurred in 18 (6.6%) patients, presenting mainly as autoimmune cytopenia (n = 10). In a multivariate analysis, female sex, young age at transplantation, family history of allergy, Epstein-Barr virus infection, and elevated eosinophil count >6 months post-transplantation were associated with an increased risk for allergy or autoimmunity. Two patients (0.7%) died from autoimmune hemolytic anemia and hemophagocytic lymphohistiocytosis, and 52 episodes of post-transplant allergy, autoimmunity, and immune-mediated disorders (37%) did not improve over time.

CONCLUSIONS

Allergy and autoimmunity are common in pediatric liver, heart, and multivisceral transplant recipients and pose a significant health burden. Further studies are required to clarify the mechanisms behind this post-transplant immune dysregulation.

Heart Transplantation in Children with Turner Syndrome: Analysis of a Linked Dataset

Turner syndrome (TS) patients with hypoplastic left heart syndrome (HLHS) have poor single ventricle palliation outcomes; therefore, consideration of other potential management strategies is important. Little is known about heart transplantation (HTx) in this group, as standard HTx databases do not allow for identification of TS. This study describes experiences and outcomes of HTx in TS using a unique linkage between the Scientific Registry of Transplant Recipients and the Pediatric Health Information System databases. All pediatric HTx recipients (2002-2016) with TS were identified in the database using ICD-9 code 758.6 (gonadal dysgenesis) in conjunction with female sex. Patient characteristics and outcomes were described. Fourteen patients with TS were identified who underwent 16 HTx procedures at eight centers. For initial HTx, HLHS was the most common indication (10/14) with a median age of 10 months (IQR 3-73 months). Median transplant-free survival following initial HTx was 4.1 years (IQR 16 days-10.5 years), with all deaths occurring in the first year post-HTx. For patients that survived past 1 year (8/14), follow-up ranged from 4.1 to 10.9 years (median 8.0 years) with no deaths observed. Our cohort demonstrates that while there is a clear risk for early mortality, there is the potential for favorable outcomes following HTx in patients with TS. Therefore, TS should not be viewed as an absolute contraindication to HTx, but careful assessment of candidate risk is needed. Primary palliation with HTx for HLHS and TS may be a reasonable consideration given the poor outcomes of single ventricle palliation in this group. Further research is needed to fully delineate the outcomes and characteristics of this unique population.

Airway inflammation and symptoms in children following liver and heart transplantation

OBJECTIVES

To describe the upper airway endoscopic findings of children with upper airway symptoms after liver transplantation (LT) or heart transplantation (HT).

METHODS

Review of children undergoing airway endoscopy after LT or HT from 2011 to 2015 at a tertiary care pediatric hospital. Airway findings, biopsy results, immunosuppression, and Epstein-Barr virus (EBV) levels were recorded.

RESULTS

Twenty-three of 158 LT (111) and HT (47) recipients underwent endoscopy. Median time from LT to endoscopy was 9 months (range 4-25) and 31 months (range 1-108) for HT. Thirteen of 23 patients presented with upper airway symptoms, and 10/23 presented with respiratory failure or for surveillance. Thirteen patients with upper airway symptoms had abnormal findings (7 LT; 6 HT), most commonly arytenoid edema (13 patients). There were five EBV-positive biopsies (four with post-transplant lymphoproliferative disorder), and six EBV-negative biopsies with lymphocytic inflammation. One biopsy demonstrated fungal infection. Immunosuppression was decreased in seven patients, and three received steroids. There were no episodes of allograft rejection. No patients had airway symptoms at last follow-up.

CONCLUSIONS

In pediatric solid organ transplant recipients, symptoms of airway obstruction are not uncommon and should be evaluated with endoscopy. Endoscopy without symptoms is low-yield. Treatment with decreased immunosuppression improved airway symptoms.

Autoimmune enteropathy and hepatitis in pediatric heart transplant recipient

AIE is a rare disorder in children that presents with severe diarrhea and malabsorption, caused by immune-mediated damage to intestinal mucosa. AIE is often associated with various syndromes of immunodeficiency including IPEX syndrome (immune dysregulation, polyendocrinopathy and enteropathy, X-linked). Dysfunctional T regulatory cells are the source of pathology in both IPEX syndrome and AIE as they are essential in maintaining tolerance to self-antigens and eliminating autoreactive B cells. This case report describes a 10-year-old cardiac transplant and total thymectomy patient on chronic immunosuppression with tacrolimus that presented with AIE and extraintestinal manifestations of cyclical hepatitis. Transition from tacrolimus to sirolimus successfully increased T regulatory cells and resolved enteritis and hepatitis symptoms. Data support that thymectomy at <1 year of age increases risk of autoimmune disease due to abnormal immune maturation. Studies suggest that the sirolimus promotes the upregulation of the FoxP3 protein that is classically associated with Tregs. In turn, Tregs prevent the maturation of autoreactive B cells that lead to autoimmune reactions.

An overview of the necessary thymic contributions to tolerance in transplantation

The thymus is important for the development of the immune system. However, aging leads to predictable involution of the thymus and immunodeficiency. These immunodeficiencies may be rectified with thymic rejuvenation. Atrophy of the thymus is governed by a complex interplay of molecular, cytokine and hormonal factors. Herein we review the interaction of these factors across age and how they may be targeted for thymic rejuvenation. We further discuss the growing pre-clinical evidence defining the necessary and sufficient contributions of the thymus to successful tolerance induction in transplantation.

Eosinophilic density in graft biopsies positive for rejection and blood eosinophil count can predict development of post-transplant digestive tract eosinophilia

EGID is a known post-transplant complication. Its etiology has been related to antirejection medication, but other factors may also play a role as only few transplant recipients develop EGID despite standardized treatment. This study aimed to determine whether EGID is associated with rejection events and with a specific phenotype of the rejection-positive graft biopsies in children with solid organ transplant. All patients with liver, heart, and kidney transplant followed at our institution were included in the study. Digestive tract eosinophilia was more common in heart and liver recipients and was a rare event after renal transplantation. Subjects with EGID had higher incidence of rejection and elevated peripheral blood AEC. The first rejection event and high AEC values preceded EGID diagnosis in the majority of patients. Histologically, the initial rejection-positive graft biopsy revealed accentuated eosinophilia in EGID patients compared with non-EGID cohort, which correlated with higher blood eosinophil counts at the time of first rejection episode. Prominent graft tissue and peripheral blood eosinophilia prior to EGID diagnosis suggests a predisposition for eosinophil activation in patients with post-transplant digestive eosinophilic disorder. These parameters can be used as markers for subsequent development of EGID.

Basiliximab treatment for autoimmune bowel disease in a pediatric heart transplant patient

Autoimmune-mediated bowel disease has been reported after pediatric heart transplantation. Recognition and treatment of these patients has been difficult. We describe a patient who responded to steroids and basiliximab therapy after an inflammatory process secondary to abnormal T-cell activation. Our patient is a 28-month-old female who received a heart transplant at five wk of age. At 24 months post-transplant, she developed fever and bloody stools. Initial investigations were significant for an elevated ESR (>120) and CRP (15.2). Symptoms persisted despite bowel rest and mycophenolate discontinuation. Endoscopic evaluation revealed discontinuous ulcerative disease involving esophagus, terminal ileum, right and left colon, necessitating extensive bowel resection. She had additional airway inflammation leading to a TEF at the site of esophageal ulceration, requiring tracheostomy. Immune evaluation revealed autoimmune dysregulation that responded to parenteral methylprednisolone. Chronic basiliximab therapy allowed for successful weaning of steroids with sustained remission. She has been transitioned to sirolimus and tacrolimus maintenance immunosuppression with plans to discontinue basiliximab once off steroids. In conclusion, bowel disease in the setting of pediatric heart transplantation can be severe and refractory to traditional treatment methods. Tailoring immune therapy to activated T cells can result in remission. Basiliximab therapy was used in our patient to maintain steroid-induced remission, but long-term complications of this disease process are unknown.