Impact of systemic immuno-suppression after solid organ transplantation on allergen-specific responses

Immunomodulatory Effects of Azithromycin Revisited: Potential Applications to COVID-19

The rapid advancement of the COVID-19 pandemic has prompted an accelerated pursuit to identify effective therapeutics. Stages of the disease course have been defined by viral burden, lung pathology, and progression through phases of the immune response. Immunological factors including inflammatory cell infiltration and cytokine storm have been associated with severe disease and death. Many immunomodulatory therapies for COVID-19 are currently being investigated, and preliminary results support the premise of targeting the immune response. However, because suppressing immune mechanisms could also impact the clearance of the virus in the early stages of infection, therapeutic success is likely to depend on timing with respect to the disease course. Azithromycin is an immunomodulatory drug that has been shown to have antiviral effects and potential benefit in patients with COVID-19. Multiple immunomodulatory effects have been defined for azithromycin which could provide efficacy during the late stages of the disease, including inhibition of pro-inflammatory cytokine production, inhibition of neutrophil influx, induction of regulatory functions of macrophages, and alterations in autophagy. Here we review the published evidence of these mechanisms along with the current clinical use of azithromycin as an immunomodulatory therapeutic. We then discuss the potential impact of azithromycin on the immune response to COVID-19, as well as caution against immunosuppressive and off-target effects including cardiotoxicity in these patients. While azithromycin has the potential to contribute efficacy, its impact on the COVID-19 immune response requires additional characterization so as to better define its role in individualized therapy.

Conversion from tacrolimus to sirolimus as a treatment modality in de novo allergies and immune-mediated disorders in pediatric liver transplant recipients

De novo PTAID may develop in pediatric solid organ transplant recipients, have a diverse spectrum, and are occasionally treatment resistant. Previous reports showed resolution of immune cytopenias in solid organ transplant recipients following replacement of the calcineurin inhibitor tacrolimus with the mTOR inhibitor sirolimus. Herein we describe a retrospective review (2000-2017) of subjects who developed PTAID in whom immunosuppression was changed to sirolimus. Eight recipients (6 males) of either liver (n = 7) or multivisceral transplant (n = 1) suffered from severe, treatment-resistant PTAID and were switched from tacrolimus to sirolimus. The median age at transplant was 1 year (range 0.5-2.4 years). Six (75%) recipients developed de novo allergy and 2 immune-mediated diseases. The median age at presentation of PTAID was 2.7 (1.4-9) years at a median of 1.3 (0.25-8) years after transplantation. The median time from PTAID presentation to conversion to sirolimus was 1.8 (0.45-10) years. Complete resolution of symptoms was seen in 4 (50%) patients after a median of 12 (range 4-24) months including 2 patients with immune-mediated disease, 1 eczema, and 1 with eosinophilic colitis. One patient with multiple food allergies had a partial response and 3 (38%) had no response. None of the 8 recipients developed sirolimus-attributed adverse events or acute rejection during a median follow-up of 5 (0.6-8) years after the conversion. Immunosuppression conversion from tacrolimus to sirolimus can be an effective therapy in patients suffering severe or treatment-resistant PTAID, suggesting a potential role for tacrolimus in the pathogenesis of PTAID.

Transfer and loss of allergen-specific responses via stem cell transplantation: A prospective observational study

BACKGROUND

Currently, no estimates can be made on the impact of hematopoietic stem cell transplantation on allergy transfer or cure of the disease. By using component-resolved diagnosis, we prospectively investigated 50 donor-recipient pairs undergoing allogeneic stem cell transplantation. This allowed calculating the rate of transfer or maintenance of allergen-specific responses in the context of stem cell transplantation.

METHODS

Allergen-specific IgE and IgG to 156 allergens was measured pretransplantation in 50 donors and recipients and at 6, 12 and 24 months in recipients post-transplantation by allergen microarray. Based on a mixed effects model, we determined risks of transfer of allergen-specific IgE or IgG responses 24 months post-transplantation.

RESULTS

After undergoing stem cell transplantation, 94% of allergen-specific IgE responses were lost. Two years post-transplantation, recipients' allergen-specific IgE was significantly linked to the pretransplantation donor or recipient status. The estimated risk to transfer and maintain individual IgE responses to allergens by stem cell transplantation was 1.7% and 2.3%, respectively. Allergen-specific IgG, which served as a surrogate marker of maintaining protective IgG responses, was highly associated with the donor's (31.6%) or the recipient's (28%) pretransplantation response.

CONCLUSION

Hematopoietic stem cell transplantation profoundly reduces allergen-specific IgE responses but also comes with a considerable risk to transfer allergen-specific immune responses. These findings facilitate clinical decision-making regarding allergic diseases in the context of hematopoietic stem cell transplantation. In addition, it provides prospective data to estimate the risk of transmitting allergen-specific responses via hematopoietic stem cell transplantation.

High Frequency of Concomitant Food Allergy Development and Autoantibody Formation in Children Who Have Undergone Liver Transplantation

BACKGROUND

Allergy and other immune-mediated diseases are more frequently reported in children who have undergone liver transplantation. Furthermore, autoantibodies are also prevalent, suggesting a state of immune dysregulation in these patients. Whether or not these processes occur simultaneously in the same individual has not been studied previously.

METHODS

A cohort of 43 children who had undergone liver transplantation for nonautoimmune liver disease at median age of 1.3 years was investigated for allergy and autoimmune disease. Sensitization to food and inhalant allergens was assessed, and autoantibodies were measured.

RESULTS

The prevalence of food allergy was 26% and that of respiratory allergy was 23%, whereas 33% and 26% of the subjects were sensitized to food and inhalant allergens, respectively. Autoimmune disease (ie, autoimmune hepatitis) occurred in a single individual (2%), whereas autoantibodies were present in 44% of the children. Food allergy and autoantibodies occurred concomitantly in 19% of the children, which was almost twice the frequency expected by chance (11%, P = 0.04). Respiratory allergy and the presence of autoantibodies were unrelated (12% concurrence versus the expected 10%, P = 0.73). In the logistic regression analysis, autoantibody formation was associated with discontinued immunosuppression and food allergy, with odds ratios of 13 (P = 0.01) and 7.1 (P = 0.03), respectively.

CONCLUSIONS

In contrast to respiratory allergy, food allergy and autoantibody formation occurred together in the same children who underwent liver transplantation at a frequency higher than would be expected by chance. This may reflect an underlying immune dysregulation that impairs immune tolerance to both food allergens and autoantigens.

Correlation between use of immunosuppressive agents and transplant-acquired allergies in renal transplant recipients

Background

Although immunosuppressive agents used in recipients of organ transplants can suppress T cell immune responses, type I allergy to ingested or inhaled allergens after organ transplantation have frequently been reported in pediatric patients. This study aims to investigate the relationship between the use of immunosuppressive agents and the transplant-acquired allergy (TAA) in adult renal transplant recipients (RTRs).

Methods

Seventy-nine RTRs treated in our hospital from February 2015 to February 2016 were interviewed for allergic diseases by using a standard questionnaire. UniCAP allergen screening tests were performed to detect total IgE and specific IgE levels before and after renal transplantation after the use of calcineurin inhibitor tacrolimus (FK506) or cyclosporin A (CsA). The follow-up visits were scheduled for 6 months, 1 year, 2 years, and 3 years after transplantation.

Results

Allergen sensitization occurred in 9 of 79 patients. Among them, the sensitization occurred in 2 cases within 6 months after renal transplantation, in 1 case from 6 months to 1 year, in 3 cases from 1 to 2 years, and in 3 cases from 2 to 3 years. The majority of sensitization was induced by inhaled allergens (n=7), among whom 3 patients (3/79, 3.8%) had a history of type I allergy, which occurred within 6 months after transplantation in 2 cases (allergic dermatitis) and from 2 to 3 years in 1 case (diarrhea after peanut allergy). The total IgE levels of RTRs using immunosuppressive agents at different time points including 6 months, 1 year, 2 years, and 3 years after renal transplantation were significantly lower than that before surgery (all P<0.05). Sensitization occurred in 8 RTRs using FK506 and in 1 patient treated with CsA (P=0.432), and allergies occurred in 3 RTRs using FK506 and were not found among CsA users (P=0.561).

Conclusions

Administration of immunosuppressive agents in adult RTRs cannot wholly prevent allergy or sensitization. Studies with larger sample sizes and more extended follow-up periods are still required to further explore the potential association between the use of FK506 and CSA and the allergies or sensitization.

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.

Evidence for a Role of TGF-β-Activated Kinase 1 and MAP3K7 Binding Protein 3 in Peanut-Specific T-Cell Responses

Peanut allergy is considered to be the most common cause for food-induced anaphylaxis. Currently, no approved treatment is available. Avoidance is the only measure to prevent anaphylactic reactions to peanuts. T-helper cells are of special importance for the sensitization process and the maintenance of allergic inflammation. Identifying markers of allergen-specific T-cell responses may help to develop novel treatment approaches. Therefore, we aimed to define new T-cell target genes in Ara h 2-specific T cells and to investigate the possibility of using them as biomarkers of peanut allergy in peripheral blood mononuclear cells (PBMCs). We performed whole mRNA array analysis (whole human genome oligo microarray) of in vitro expanded Ara h 2-specific T cells (CFSElowCD3+CD4+) from 5 peanut-allergic (PA) and 5 non-peanut-sensitized individuals. Expression of selected genes as a result of a two-step bioinformatic approach was confirmed in a second cohort by quantitative PCR. TGF-β- activated kinase 1 and MAP3K7 binding protein 3 (TAB3), calcium/calmodulin-dependent protein kinase type IV (CAMK4) and HemK methyltransferase family member 1 (HEMK1) were significantly upregulated in Ara h 2-specific T cells of PA patients. In addition, the expression of these genes was also assessed in unstimulated PBMCs from a cohort (n = 43) of PA, atopic non-PA, and nonatopic controls. Interestingly, in unstimulated PBMCs, TAB3 expression was significantly downregulated in PA patients compared to atopic non-PA individuals. Thus, TAB3 may play a significant role at the level of T-cell activation and may also be a candidate biomarker for PA.

Increase of natural killer cells in children with liver transplantation-acquired food allergy

BACKGROUND

Transplantation-acquired food allergies (TAFA) are frequently reported and considered to be caused by immunosuppressive therapy. The aim of this study was to investigate the allergic and immunologic responses in children who had liver or kidney transplantations.

METHODS

Twelve children receiving liver transplantations and 10 children receiving kidney transplantations were investigated. All children underwent the allergy work-up and in most of them, lymphocyte screening and serum cytokine measurements were also performed.

RESULTS

TAFA were found in 7/12 (58%) children with liver transplantations and in none of the 10 children with kidney transplantations. The mean age at transplantation was significantly lower in children who underwent liver transplantations (p<0.001). The immunosuppressive therapy administered to children with liver transplantation was tacrolimus in 11 patients and cyclosporine in one patient, while all 10 children with kidney transplantation received tacrolimus plus mycophenolate. The most common antigenic food was egg. The natural killer (NK) cell numbers were significantly higher in liver-transplant children than in kidney-transplant children. No significant differences were found in the serum cytokine levels.

CONCLUSIONS

This study confirms that liver-transplant children treated with tacrolimus alone have a higher risk of developing TAFA than kidney-transplant children treated with tacrolimus plus mycophenolate. NK cells might be involved in this difference.

Post-transplantation Development of Food Allergies

PURPOSE OF REVIEW

The development of food allergies is increasingly being recognized as a post-solid organ transplant complication. In this article, we review the spectrum of post-transplant food allergy development and the proposed mechanisms for de novo food allergies and the clinical significance they pose.

RECENT FINDINGS

The development of new food allergies is disproportionately associated with pediatric liver transplants, where it occurs in up to 38% of select populations. The mechanism of food allergy development is not completely understood; however, it is likely promoted by unbalanced immune suppression. De novo food allergy development is a common complication of solid organ transplants with the highest risk occurring in pediatric liver transplant recipients. There are likely multiple mechanisms for food allergy development including passive transfer of membrane-bound IgE and lymphocytes from donor to recipient, as well as loss of food tolerance and active development of new food allergies. The optimal management of food allergies following organ transplants has not been well researched but may include changing the immune suppression regimen if the food allergy does not resolve without intervention.

Factors Associated with Development of Food Allergy in Young Children after Liver Transplantation: A Retrospective Analysis of 10 Years' Experience

BACKGROUND

Although development of food allergy after liver transplantation is most commonly described in young children, little is known about identification of young liver-transplant recipients who are at risk of food allergy.

OBJECTIVE

This study aimed to identify the types of food allergy and the risk factors for the development of food allergy after liver transplantation.

METHODS

This was a retrospective analysis of pediatric liver transplant recipients in our organ transplantation center during 2005-2015. Relevant data of all patients who underwent liver transplantation were extracted from the center's database and the medical records. Differences in patients' characteristics were evaluated for associations between food allergy and potential risk factors. Logistic regression models were used to calculate adjusted odds ratios.

RESULTS

We obtained the data of 206 patients under 36 months of age, 42 (20.4%) of whom developed food allergy after liver transplantation. The allergy was IgE-mediated-only in 30 (71.4%) and non-IgE-mediated-only in 10 (23.8%). Multivariate analysis found eczema at liver transplantation to be a significant risk factor (adjusted odds ratio [aOR] 2.41, 95% confidence interval [CI] 1.14-4.77, P < .05). Eczema increased the risk of developing IgE-mediated food allergy after liver transplantation (aOR 3.13, 95% CI 1.41-6.93, P < .01), whereas no significant association was observed with non-IgE-mediated food allergy.

CONCLUSIONS

We identified eczema at liver transplantation as a significant risk factor for the development of IgE-mediated food allergy after liver transplantation, but not non-IgE-mediated food allergy. Our findings may contribute to a better understanding of the susceptible subgroup requiring special caution and to the establishment of effective strategies for prevention.

Decrease of Airway Allergies After Lung Transplantation Is Associated With Reduced Basophils and Eosinophils

BACKGROUND

Allergies are hypersensitive reactions of the immune system on antigen exposure similar to immune reactions after transplantation (Tx). Their activity can change after Tx. The lung as a transplantable organ is challenged two-fold, by antigens from the blood and the air environment. Herein we analyzed if airway allergies change after lung Tx.

METHODS

We systematically reviewed patients' airway allergies before and after lung Tx between 1992 and 2014. The course of lymphocytes, thrombocytes, and leukocytes, among them neutrophils, eosinophils, and basophils, was analyzed in patients in whom airway allergies have changed and in whom they did not change.

RESULTS

From 362 lung transplanted patients, 44 patients had suffered from allergies before Tx (12.2%). In 20 of these patients (45.5%), airway allergies disappeared completely within 1 year after lung Tx and were persistently absent thereafter. In these patients, basophils and eosinophils decreased significantly (P < .0012); in contrast, cells did not decrease in patients whose allergies did not disappear. Leukocytes overall, and in particular, neutrophils, decreased significantly in patients whose allergy disappeared (P < .014, P < .012, respectively).

CONCLUSIONS

Airway allergies disappeared in almost half of cases after lung Tx. Along with this reduction, basophils and eosinophils decreased as potentially responsible cells for this phenomenon. These findings may stimulate intensified research on basophils and eosinophils as major drivers of airway allergies.

Inflammatory Cutaneous Diseases in Renal Transplant Recipients

Kidney transplant recipients frequently suffer from skin infections and malignancies, possibly due to the effects of long-term immunosuppressive therapy. While the relationships between immunosuppression and these pathological conditions have been widely investigated, little is known about the relative incidence and characteristics of inflammatory skin diseases in this type of patient. In this study, we analyze the incidence of a number of inflammatory cutaneous diseases in a cohort of patients who underwent kidney transplantation. Although our study shows a relatively low incidence of these pathologies in transplanted patients-in agreement with the general action of immunosuppressant therapies in reducing inflammation-we scored a different efficacy of the various immunosuppressive regimens on inflammatory and autoimmune skin diseases. This information can be key for designing immunosuppressive regimens and devising accurate follow-up protocols.

Immunohistopathology of the Newly Discovered Giant Papillae Tongue Disorder in Organ-Transplanted Children

BACKGROUND

Giant papillae tongue disorder (GPTD) is a newly discovered, long-lasting clinical disorder that may develop in organ-transplanted pediatric recipients. The key feature of this disorder is the unique tongue lesion, which comprises swollen fungiform papillae. The aim of this study was to characterize the immunohistopathology of this novel inflammatory condition.

METHODS

Six organ transplanted children with GPTD were included in the study. Routine histopathology and immunohistochemical stainings for CD3, CD4, CD8, CD25, FOXP3, CD20, CD138, CD68, CD1a, CD15, CD23, and mast cell tryptase were performed.

RESULTS

Immunohistochemical analyses of the oral lesions revealed a subepithelial infiltrate that was primarily composed of CD3- and CD4-positive T cells, CD20-expressing B cells, macrophages, and CD138-positive plasma cells. The CD20-positive cells did not display the typical B cell morphology, having in general a more dendritic cell-like appearance. The CD138-expressing plasma cells were distinctly localized as a dense infiltrate beneath the accumulation of T cells and B cells. Increased numbers of CD1a-expressing Langerhans cells were detected both in the epithelium and connective tissue. Because no granulomas were observed and only single lesional eosinophils were detected, GPTD does not resemble a granulomatous or eosinophilic condition.

CONCLUSIONS

We describe for the first time the immunopathological characteristics of a novel inflammatory disorder of the oral cavity, which may develop after solid organ transplantation in children.

Cytokine profile of food-allergic post-liver transplant children is identified by high levels of IL-5 and low IL-10 secretion from patients' peripheral blood mononuclear cells

Severe allergic reaction to food following liver transplantation is a well-known phenomenon. However, the mechanisms underlying this phenomenon are not yet elucidated. This study aimed to reveal the nature of the immune response in post-transplanted allergic patients and compare them to non-allergic transplanted as well as allergic and non-allergic control subjects, with focus on cytokine milieu. Post-liver transplant patients with and without allergic reactions as well as food-allergic but otherwise healthy and healthy non-allergic control patients were recruited. We reviewed patient records and routine laboratory tests and assayed subjects' PBMCs, studying cytokine secretion profile in response to different stimuli. Post-transplant patients with food allergy showed a unique cytokine profile in response to various stimuli, with extremely elevated IL-5, low IL-10 secretion, and somewhat higher IFN-γ. T regulatory cell number was not significantly different among the groups of patients and controls. Immune response of food-allergic post-liver transplant patients is identified by a unique cytokine profile when compared to allergic but otherwise healthy individuals.

Atopic allergy and chronic inflammation of the oral mucosa in a 3-year-old boy after heart transplantation - diagnostic and therapeutic difficulties

In recent years, we have been observing an increased proportion of atopic diseases in children after solid organ transplantation. The pathogenesis of post-transplantation allergy is not completely understood and probably involves several factors, including immunosuppressive therapy. In this paper we present a case of 3-year old boy, after orthotopic heart transplantation at 6 months of age, with symptoms of food allergy associated with atopic dermatitis and changes in the orofacial area. The mentioned symptoms and elevated levels of total and specific IgE occurred with a year of transplant. Because of failure to achieve remission after typical allergy therapy we suspected that the reason of allergy in this case can be immunosuppressive therapy.

Mechanisms of allergen-specific immunotherapy and immune tolerance to allergens

Substantial progress in understanding mechanisms of immune regulation in allergy, asthma, autoimmune diseases, tumors, organ transplantation and chronic infections has led to a variety of targeted therapeutic approaches. Allergen-specific immunotherapy (AIT) has been used for 100 years as a desensitizing therapy for allergic diseases and represents the potentially curative and specific way of treatment. The mechanisms by which allergen-AIT has its mechanisms of action include the very early desensitization effects, modulation of T- and B-cell responses and related antibody isotypes as well as inhibition of migration of eosinophils, basophils and mast cells to tissues and release of their mediators. Regulatory T cells (Treg) have been identified as key regulators of immunological processes in peripheral tolerance to allergens. Skewing of allergen-specific effector T cells to a regulatory phenotype appears as a key event in the development of healthy immune response to allergens and successful outcome in AIT. Naturally occurring FoxP3⁺ CD4⁺CD25⁺ Treg cells and inducible type 1 Treg (Tr1) cells contribute to the control of allergen-specific immune responses in several major ways, which can be summarized as suppression of dendritic cells that support the generation of effector T cells; suppression of effector Th1, Th2 and Th17 cells; suppression of allergen-specific IgE, and induction of IgG4; suppression of mast cells, basophils and eosinophils and suppression of effector T cell migration to tissues. New strategies for immune intervention will likely include targeting of the molecular mechanisms of allergen tolerance and reciprocal regulation of effector and regulatory T cell subsets.

The Induction of IL-33 in the Sinus Epithelium and Its Influence on T-Helper Cell Responses

BACKGROUND

Chronic rhinosinusitis (CRS) is characterized by epithelial activation and chronic T-cell infiltration in sinonasal mucosa and nasal polyps. IL-33 is a new cytokine of the IL-1 cytokine family that has a pro-inflammatory and Th2 type cytokine induction property. The role of IL-33 in the pathomechanisms of CRS and its interaction with other T cell subsets remain to be fully understood.

METHODS

The main trigger for IL-33 mRNA expression in primary human sinonasal epithelial cells was determined in multiple cytokine and T-cell stimulated cultures. The effects of IL-33 on naïve, Th0 and memory T-cells was studied by PCR, ELISA and flow cytometry. Biopsies from sinus tissue were analyzed by PCR and immunofluorescence for the presence of different cytokines and receptors with a special focus on IL-33.

RESULTS

IL-33 was mainly induced by IFN-γ in primary sinonasal epithelial cells, and induced a typical CRSwNP Th2 favoring cytokine profile upon co-culture with T-helper cell subsets. IL-33 and its receptor ST2 were highly expressed in the inflamed epithelial tissue of CRS patients. While IL-33 was significantly up-regulated in the epithelium for CRSsNP, its receptor was higher expressed in sinus tissue from CRSwNP.

CONCLUSIONS

The present study delineates the influence of IL-33 in upper airway epithelium and a potential role of IL-33 in chronic inflammation of CRSwNP by enhancing Th2 type cytokine production, which could both contribute to a further increase of an established Th2 profile in CRSwNP.

Azithromycin and the treatment of lymphocytic airway inflammation after lung transplantation

Lymphocytic airway inflammation is a major risk factor for chronic lung allograft dysfunction, for which there is no established treatment. We investigated whether azithromycin could control lymphocytic airway inflammation and improve allograft function. Fifteen lung transplant recipients demonstrating acute allograft dysfunction due to isolated lymphocytic airway inflammation were prospectively treated with azithromycin for at least 6 months (NCT01109160). Spirometry (FVC, FEV1 , FEF25-75 , Tiffeneau index) and FeNO were assessed before and up to 12 months after initiation of azithromycin. Radiologic features, local inflammation assessed on airway biopsy (rejection score, IL-17(+)  cells/mm(2) lamina propria) and broncho-alveolar lavage fluid (total and differential cell counts, chemokine and cytokine levels); as well as systemic C-reactive protein levels were compared between baseline and after 3 months of treatment. Airflow improved and FeNO decreased to baseline levels after 1 month of azithromycin and were sustained thereafter. After 3 months of treatment, radiologic abnormalities, submucosal cellular inflammation, lavage protein levels of IL-1β, IL-8/CXCL-8, IP-10/CXCL-10, RANTES/CCL5, MIP1-α/CCL3, MIP-1β/CCL4, Eotaxin, PDGF-BB, total cell count, neutrophils and eosinophils, as well as plasma C-reactive protein levels all significantly decreased compared to baseline (p < 0.05). Administration of azithromycin was associated with suppression of posttransplant lymphocytic airway inflammation and clinical improvement in lung allograft function.

Translational research in pediatrics III: bronchoalveolar lavage

The role of flexible bronchoscopy and bronchoalveolar lavage (BAL) for the care of children with airway and pulmonary diseases is well established, with collected BAL fluid most often used clinically for microbiologic pathogen identification and cellular analyses. More recently, powerful analytic research methods have been used to investigate BAL samples to better understand the pathophysiological basis of pediatric respiratory disease. Investigations have focused on the cellular components contained in BAL fluid, such as macrophages, lymphocytes, neutrophils, eosinophils, and mast cells, as well as the noncellular components such as serum molecules, inflammatory proteins, and surfactant. Molecular techniques are frequently used to investigate BAL fluid for the presence of infectious pathologies and for cellular gene expression. Recent advances in proteomics allow identification of multiple protein expression patterns linked to specific respiratory diseases, whereas newer analytic techniques allow for investigations on surfactant quantification and function. These translational research studies on BAL fluid have aided our understanding of pulmonary inflammation and the injury/repair responses in children. We review the ethics and practices for the execution of BAL in children for translational research purposes, with an emphasis on the optimal handling and processing of BAL samples.

New developments in transplant-acquired allergies

Transplant-acquired allergy (TAA) was firstly described as transplant-acquired food allergy (TAFA) after bone marrow transplantations and mostly observed in a transient form. The picture is complicated by numerous case reports of TAFA after the receipt of liver grafts from donors with no documented history of food allergy. The estimated prevalence of TAFA among young children in the literature has been documented in various studies ranging from 6% to 57%. Although TAA is mostly found to be associated with liver transplantation; it has been recently reported to be related with heart, intestinal, lung and even renal transplantations in adults. Previous reviews of published cases of liver TAA misleadingly emphasized the predominance of children and the absence of TAA in cardiac, pulmonary, and renal transplant recipients. In different studies, the male/female ratio is equal. Literature data suggest that children with TAFA typically present within the first year after surgery and are typically allergic to multiple foods. The pathogenesis of TAA is not still completely understood. Most of the studies support the concept that the functioning liver itself, and not only tacrolimus immunosuppression, is one of the main contributors to TAA in these patients. In the light of recent findings, other possible mechanisms can be summarized as following: (1) the recovery of delayed type hypersensitivity; (2) late manifestation of food allergy; (3) intestinal injury as well as inhibition of cellular energy production by tacrolimus; and (4) transfer of food-specific IgE or lymphocytes. Thus, interplay between hematopoietic cells from the transplanted organ and recipient specific factors (e.g., younger age and atopic background) seem to underlie the development of TAA. Most patients will have symptomatic improvement following reduced immunosuppression and an appropriately restricted diet. Nevertheless, some studies suggest that atopic diseases occur in some of pediatric liver transplant recipients, with manifestations including food allergy, eczema, allergic rhinitis, and asthma. More studies would be needed including greater number of patients to determine whether TAA is transient or not in pediatric/adult solid organ recipients.

Post-transplant food allergy in children is associated with liver and not with renal transplantation: a monocentric comparative study

Food allergy is increasingly reported after paediatric liver transplantation. The underlying physiopathological mechanism remains incompletely understood. Therefore, we aimed to determine the incidence, clinical presentation, possible risk factors, and prognosis of post-transplant food allergy in children currently followed after liver and renal transplantation. The study population consists of 49 liver and 21 renal transplant patients transplanted between the age of 22 months and 15 years. Data were collected retrospectively from medical records and via a doctor's questionnaire taken from the parents in a monocentric setting. Post-transplant food allergy has developed in 13 liver transplant patients and in none of the renal transplant recipients. Within the liver transplant group, median age at liver transplantation is significantly lower in the food-allergic (10 months) versus non-food-allergic group (3.3 years; p = 0.002). The use of tacrolimus as primary maintenance immunosuppression is associated with food allergy (p = 0.032) and mean donor age is significantly lower in the food-allergic group (p = 0.009). Compared to the renal transplant group, median age at transplantation is significantly lower in the liver patients (p < 0.001). No significant differences are found in primary immunosuppressive regimens between renal and liver transplant patients.

CONCLUSION

Post-transplant food allergy is an important clinical problem in children after liver transplantation which does not affect renal transplant patients despite similar immunosuppressive regimens. Within the group of liver transplant recipients, tacrolimus use, young age at time of transplant and younger donor age were associated with the development of food allergy.

Reduced varicella-zoster-virus (VZV)-specific lymphocytes and IgG antibody avidity in solid organ transplant recipients

BACKGROUND

Varicella-zoster-virus (VZV) infection may cause significant morbidity and mortality in immunocompromised patients. So far, only IgG-anti-VZV antibody concentrations were used to estimate immunity against VZV, but the antibody binding strength (avidity) together with VZV-specific cellular responses have not been evaluated in solid organ transplant (SOT) recipients.

METHODS

Thus, we assessed the humoral and cellular immune responses to two doses of the VZV vaccine (vacc) and wild-type VZV infection (wt) in 23 kidney (KTx) and 19 liver transplant (LTx) recipients including children and adults compared to 48 healthy controls (HC) for measurement of IgG-anti-VZV relative avidity index (RAI) and frequency of VZV-specific peripheral blood mononuclear cells (PBMCs) in vaccinated individuals using an adapted ELISA and IFN-gamma ELISPOT, respectively.

RESULTS

KTx(wt) (median RAI 72.3%) or LTx(wt) (79.2%) and KTx(vacc) (91.0%) or LTx(vacc) (72.5%) showed lower avidities compared to HC(wt) (84.5%) and HC(vacc) (94.0%), respectively, despite equally distributed IgG-anti-VZV concentrations. RAI>60% (high avidity) was detected in all HC, but only in 69.0% of SOT patients. KTx(vacc) (median 64 spot forming units SFU/500,000 PBMCs) and LTx(vacc) (67 SFU) had significantly lower VZV-specific cellular responses compared to HC(vacc) (268 SFU).

CONCLUSIONS

The diminished cellular reactivity to VZV has to be considered in SOT patients receiving immunosuppressive treatments when evaluating immunity against VZV. IgG antibody avidity and VZV-specific cellular responses may serve as additional markers to evaluate immunity against VZV in SOT recipients. The role of wild-type exposures and endogenous VZV re-activation on long-term immunity in SOT patients has to be awaited to establish recommendations for vaccine spacing in these patients, considering immunogenicity and safety aspects.

Novel developments in the mechanisms of immune tolerance to allergens

Allergy is the result of a disbalanced immune response to environmental innocuous antigens. Despite of accumulating data to define the pathomechanisms that take place in case of allergic diseases a detailed understanding of sequence of events that lead to the "normal" scenario of tolerance development are still under debate. Allergen-specific immunotherapy is the only causal treatment of allergic diseases. It modifies the immune response to a particular antigen to achieve tolerance against the symptom-causing allergen. This process is considered to mirror physiological peripheral tolerance induction. A number of immunological changes have been described to occur under allergen immunotherapy, including the generation of allergen-specific regulatory T cells, the induction of allergen-specific IgG4, an increase in the Th1/Th2 cytokine ratio and decreased activation and function of effector cells such as mast cells, basophils and eosinophils.

Preventive and therapeutic effects of rapamycin, a mammalian target of rapamycin inhibitor, on food allergy in mice

BACKGROUND

Because few curative treatments are available for food allergy, we investigated the therapeutic potential of rapamycin, a mammalian target of rapamycin (mTOR) inhibitor, on mouse food allergy.

METHODS

The preventive and therapeutic effects of oral rapamycin on anaphylactic symptoms induced by oral ovalbumin (OVA) challenge in food allergy mice were investigated. Mast cell functions in response to rapamycin were also measured in the passive systemic anaphylaxis model and bone marrow-derived mast cells (BMMCs).

RESULTS

Daily rapamycin from the first challenge (preventive protocol) attenuated food allergy symptoms including diarrhea, anaphylactic reactions, and hypothermia in mice. The treatment decreased the challenge-induced increases in mouse mast cell protease-1 in serum and mast cell numbers in the intestine. Notably, the mice that already showed food allergy symptoms by previous challenges recovered from the disease with daily administration of rapamycin (therapeutic protocol). Anti-OVA IgG1 and IgE levels in serum, as well as IFN-γ, IL-4, IL-13, IL-9, IL-10, and IL-17 secretion from splenocytes, were decreased by the treatments. In contrast, a single dose of rapamycin failed to affect passive systemic anaphylaxis. Spontaneous and IL-9-dependent survival and IgE-induced IL-13 secretion, but not degranulation, of BMMCs were reduced by rapamycin.

CONCLUSION

Our data show that mouse food allergy was attenuated by rapamycin through an immunosuppressive effect and inhibition of intestinal mast cell hyperplasia. Inhibition of the IL-9 production-mast cell survival axis is one of the mechanisms of the therapeutic effect of rapamycin. Rapamycin and other mTOR inhibitors might be good candidates for therapeutic drugs for food allergy.

[Pharmacoprophylaxis and co-medications in allergen-specific immunotherapy]

Drugs that are used in relation to allergen-specific immunotherapy (SIT) can be separated into pharmacoprophylaxis to avoid or decrease local and systemic adverse effects of SIT and in co-medications to treat other diseases. Regarding pharmacoprophylaxis, H1-antihistamines are able to reduce local and mild systemic, but not severe systemic side effects of SIT. H1-antihistamines do not attenuate the efficacy of SIT. Severe systemic side effects have been blocked in some cases with omalizumab; currently this agent can be used off-label during venom SIT. With regard to co-medication, the concomitant use of immunomodulating drugs during SIT must be individualized, if the effective profile and side effects of the immunomodulating drug are well-known and a negative effect on SIT is not likely. Recently approved immunosuppressive drugs and biologics are perceived critically due to their unpredictable immunologic effects. For forensic reasons cardioselective beta blockers should be discontinued although no data are available demonstrating adverse effects. If discontinuation is not justified and venom SIT is indicated, SIT can be performed while taking beta blockers. In contrast, ACE-inhibitors should always be stopped in patients with insect venom allergy.

Allergic sensitization in kidney-transplanted patients prevails under tacrolimus treatment

BACKGROUND

Type I allergies have repeatedly been reported after solid organ transplantation despite T cell-targeted immunosuppressive therapy. A causal relationship with tacrolimus has been proposed.

OBJECTIVE

The present study directly compared the occurrence of allergic sensitization and disease under tacrolimus- vs. cyclosporin A-based immunosuppressive therapy.

METHODS

The prevalences of IgE-mediated sensitization and allergy were assessed in a cross-sectional study of kidney-transplanted adults receiving tacrolimus (n = 100) or cyclosporin A (n = 100).

METHODS

included a standardized questionnaire, skin prick test and measurement of total and specific IgE against common nutritive and inhalant allergens. Results The prevalence of sensitization was significantly higher in the tacrolimus- than in the cyclosporin A-treated group (34%, n = 34, vs. 20%, n = 20; P = 0.026). The rate of clinically relevant allergy in patients receiving tacrolimus was twice that in patients receiving cyclosporin A (15%, n = 15, vs. 8%, n = 8; P = 0.12). No other factor (age, serum drug level, concomitant immunosuppressive medication, time since transplantation, underlying disease) was found to have an influence on sensitization or allergy prevalence (logistic regression).

CONCLUSION AND CLINICAL RELEVANCE

Our results suggest that post-transplant immunosuppression with tacrolimus is associated with an increased occurrence of IgE-mediated sensitization and probably manifestation of allergic disease, which has to be treated specifically despite immunosuppressive therapy.