Advances and Ongoing Challenges in Eosinophilic Gastrointestinal Disorders presented at the CEGIR/TIGERS Symposium at the 2024 American Academy of Allergy, Asthma, & Immunology Meeting.

The Consortium of Eosinophilic Gastrointestinal disease Researchers (CEGIR) and The International Gastrointestinal Eosinophil Researchers (TIGERS) organized a day-long symposium at the 2024 Annual Meeting of the American Academy of Allergy, Asthma & Immunology. The symposium featured new discoveries in basic and translational research and debates on the mechanisms and management of eosinophilic gastrointestinal diseases (EGIDs). Updates on recent clinical trials and consensus guidelines were also presented. Herein, we summarize the updates on EGIDs presented at the symposium.

The Role of Interferon-γ in Autoimmune Polyendocrine Syndrome Type 1.

BACKGROUND: Autoimmune polyendocrine syndrome type 1 (APS-1) is a life-threatening, autosomal recessive syndrome caused by autoimmune regulator (AIRE) deficiency. In APS-1, self-reactive T cells escape thymic negative selection, infiltrate organs, and drive autoimmune injury. The effector mechanisms governing T-cell-mediated damage in APS-1 remain poorly understood. METHODS: We examined whether APS-1 could be classified as a disease mediated by interferon-γ. We first assessed patients with APS-1 who were participating in a prospective natural history study and evaluated mRNA and protein expression in blood and tissues. We then examined the pathogenic role of interferon-γ using Aire-/-Ifng-/- mice and Aire-/- mice treated with the Janus kinase (JAK) inhibitor ruxolitinib. On the basis of our findings, we used ruxolitinib to treat five patients with APS-1 and assessed clinical, immunologic, histologic, transcriptional, and autoantibody responses. RESULTS: Patients with APS-1 had enhanced interferon-γ responses in blood and in all examined autoimmunity-affected tissues. Aire-/- mice had selectively increased interferon-γ production by T cells and enhanced interferon-γ, phosphorylated signal transducer and activator of transcription 1 (pSTAT1), and CXCL9 signals in multiple organs. Ifng ablation or ruxolitinib-induced JAK-STAT blockade in Aire-/- mice normalized interferon-γ responses and averted T-cell infiltration and damage in organs. Ruxolitinib treatment of five patients with APS-1 led to decreased levels of T-cell-derived interferon-γ, normalized interferon-γ and CXCL9 levels, and remission of alopecia, oral candidiasis, nail dystrophy, gastritis, enteritis, arthritis, Sjögren's-like syndrome, urticaria, and thyroiditis. No serious adverse effects from ruxolitinib were identified in these patients. CONCLUSIONS: Our findings indicate that APS-1, which is caused by AIRE deficiency, is characterized by excessive, multiorgan interferon-γ-mediated responses. JAK inhibition with ruxolitinib in five patients showed promising results. (Funded by the National Institute of Allergy and Infectious Diseases and others.).

Mepolizumab incompletely suppresses clinical flares in a pilot study of episodic angioedema with eosinophilia.

BACKGROUND: Episodic angioedema with eosinophilia (EAE) is a rare multilineage cyclic syndrome of unknown etiology characterized by episodes of angioedema, myalgia, fatigue, and fever that occur every 3 to 8 weeks and resolve between episodes without therapy. Cyclic elevations in serum IL-5 levels and neutrophils precede the increase in absolute eosinophil count (AEC) in most patients. OBJECTIVE: We sought to assess the role of IL-5-driven eosinophilia in the clinical manifestations of EAE. METHODS: An open-label pilot study of mepolizumab (700 mg intravenously monthly for 3 months followed by sequential dose reduction to the Food and Drug Administration-approved dose of 300 mg subcutaneously monthly) was conducted. The primary end point was reduction in the number and severity of clinical symptoms as assessed by patient-reported symptom questionnaires. Secondary end points were greater than or equal to 75% reduction in peak AEC after 1 dose of mepolizumab and sustained reduction in AEC after 3 doses of mepolizumab. Exploratory end points included effects of mepolizumab treatment on other cell lineages (numbers and surface marker expression), levels of plasma mediators, and biomarkers of eosinophil activation. RESULTS: Four female and 1 male (median age, 45 years) participants with EAE were enrolled. None of the 5 participants experienced a reduction in the number of symptomatic flares on mepolizumab therapy, and 1 participant withdrew before study completion because of lack of improvement. Peak AEC was reduced by 75% or more in 3 participants after the first dose of mepolizumab and in 4 participants after 3 doses. CONCLUSIONS: In a small cohort of participants with EAE, mepolizumab was unsuccessful in substantially reducing clinical symptoms despite reduction in AEC.

False-Negative Testing for FIP1L1::PDGFRA by Fluorescence in situ Hybridization Is a Frequent Cause of Diagnostic Delay.

The imatinib-sensitive fusion gene FIP1L1::PDGFRA is the most frequent molecular abnormality identified in patients with eosinophilic myeloid neoplasms. Rapid recognition of this mutation is essential given the poor prognosis of PDGFRA-associated myeloid neoplasms prior to the availability of imatinib therapy. We report a case of a patient in whom delayed diagnosis resulted in cardiac transplantation for eosinophilic endomyocardial fibrosis. The delay in diagnosis was due, in part, to a false-negative result in fluorescence in situ hybridization (FISH) testing for FIP1L1::PDGFRA. To explore this further, we examined our cohort of patients presenting with confirmed or suspected eosinophilic myeloid neoplasms and found 8 additional patients with negative FISH results despite a positive reverse-transcriptase polymerase chain reaction test for FIP1L1::PDGFRA. More importantly, false-negative FISH results delayed the median time to imatinib treatment by 257 days. These data emphasize the importance of empiric imatinib therapy in patients with clinical features suggestive of PDGFRA-associated disease.

Recent advances in understanding the role of eosinophils.

Our understanding of eosinophil biology, development, and regulation has dramatically increased in the past decade, leading to new paradigms for the role of eosinophils in human health and disease and, perhaps more importantly, providing insights toward novel treatment strategies in the fight against eosinophil-mediated inflammation. In this review, we discuss recent advances regarding the role of eosinophils in host-viral defense, eosinophil heterogeneity, and eosinophil-targeted therapies.

Nodular regenerative hyperplasia in X-linked agammaglobulinemia: An underestimated and severe complication.

BACKGROUND: Late-onset complications in X-linked agammaglobulinemia (XLA) are increasingly recognized. Nodular regenerative hyperplasia (NRH) has been reported in primary immunodeficiency but data in XLA are limited. OBJECTIVES: This study sought to describe NRH prevalence, associated features, and impact in patients with XLA. METHODS: Medical records of all patients with XLA referred to the National Institutes of Health between October 1994 and June 2019 were reviewed. Liver biopsies were performed when clinically indicated. Patients were stratified into NRH+ or NRH- groups, according to their NRH biopsy status. Fisher exact test and Mann-Whitney test were used for statistical comparisons. RESULTS: Records of 21 patients with XLA were reviewed, with a cumulative follow-up of 129 patient-years. Eight patients underwent ≥1 liver biopsy of whom 6 (29% of the National Institutes of Health XLA cohort) were NRH+. The median age at NRH diagnosis was 20 years (range, 17-31). Among patients who had liver biopsies, alkaline phosphatase levels were only increased in patients who were NRH+ (P = .04). Persistently low platelet count (<100,000 per µL for >6 months), mildly to highly elevated hepatic venous pressure gradient and either hepatomegaly and/or splenomegaly were present in all patients who were NRH+. In opposition, persistently low platelet counts were not seen in patients who were NRH-, and hepatosplenomegaly was observed in only 1 patient who was NRH-. Hepatic venous pressure gradient was normal in the only patient tested who was NRH-. All-cause mortality was higher among patients who were NRH+ (5 of 6, 83%) than in the rest of the cohort (1 of 15, 7% among patients who were NRH- and who were classified as unknown; P = .002). CONCLUSIONS: NRH is an underreported, frequent, and severe complication in XLA, which is associated with increased morbidity and mortality.

Regional cerebral cholinergic nerve terminal integrity and cardinal motor features in Parkinson's disease.

Clinical effects of anti-cholinergic drugs implicate cholinergic systems alterations in the pathophysiology of some cardinal motor impairments in Parkinson's disease. The topography of affected cholinergic systems deficits and motor domain specificity are poorly understood. Parkinson's disease patients (n = 108) underwent clinical and motor assessment and vesicular acetylcholine transporter [18F]-fluoroethoxybenzovesamicol PET imaging. Volumes-of-interest-based analyses included detailed thalamic and cerebellar parcellations. Successful PET sampling for most of the small-sized parcellations was available in 88 patients. A data-driven approach, stepwise regression using the forward selection method, was used to identify cholinergic brain regions associating with cardinal domain-specific motor ratings. Regressions with motor domain scores for model-selected regions followed by confounder analysis for effects of age of onset, duration of motor disease and levodopa equivalent dose were performed. Among 7 model-derived regions associating with postural instability and gait difficulties domain scores three retained significance in confounder variable analysis: medial geniculate nucleus (standardized ß = -0.34, t = -3.78, P = 0.0003), lateral geniculate nucleus (ß = -0.32, t = -3.4, P = 0.001) and entorhinal cortex (ß = -0.23, t = -2.6, P = 0.011). A sub-analysis of non-episodic postural instability and gait difficulties scores demonstrated significant effects of the medial geniculate nucleus, entorhinal cortex and globus pallidus pars interna. Among 6 tremor domain model-selected regions two regions retained significance in confounder variable analysis: cerebellar vermis section of lobule VIIIb (ß = -0.22, t = -2.4, P = 0.021) and the putamen (ß = -0.23, t = -2.3, P = 0.024). None of the three model-selected variables for the rigidity domain survived confounder analysis. Two out of the four model-selected regions for the distal limb bradykinesia domain survived confounder analysis: globus pallidus pars externa (ß = 0.36, t = 3.9, P = 0.0097) and the paracentral lobule (ß = 0.26, t = 2.5, P = 0.013). Emphasizing the utility of a systems-network conception of the pathophysiology of Parkinson's disease cardinal motor features, our results are consistent with specific deficits in basal forebrain corticopetal, peduncupontine-laterodorsal tegmental complex, and medial vestibular nucleus cholinergic pathways, against the background of nigrostriatal dopaminergic deficits, contributing significantly to postural instability, gait difficulties, tremor and distal limb bradykinesia cardinal motor features of Parkinson's disease. Our results suggest significant and distinct consequences of degeneration of cholinergic peduncupontine-laterodorsal tegmental complex afferents to both segments of the globus pallidus. Non-specific regional cholinergic nerve terminal associations with rigidity scores likely reflect more complex multifactorial signalling mechanisms with smaller contributions from cholinergic pathways.

Genetic susceptibility to fungal infection in children.

PURPOSE OF REVIEW: Fungal infections have steadily increased in incidence, emerging as a significant cause of morbidity and mortality in patients with iatrogenic immunosuppression. Simultaneously, we have witnessed a growing population of newly described inherited immune disorders that have enhanced our understanding of the human immune response against fungi. In the present review, we provide an overview and diagnostic roadmap to inherited disorders which confer susceptibility to superficial and invasive fungal infections. RECENT FINDINGS: Inborn errors of fungal immunity encompass a heterogeneous group of disorders, some of which confer fungal infection-specific susceptibility, whereas others also feature broader infection vulnerability and/or noninfectious manifestations. Infections by Candida, Aspergillus, endemic dimorphic fungi, Pneumocystis, and dermatophytes along with their organ-specific presentations provide clinicians with important clues in the assessment of patients with suspected immune defects. SUMMARY: The absence of iatrogenic risk factors should raise suspicion for inborn errors of immunity in children and young adults with recurrent or severe fungal diseases. Expeditious diagnosis and prompt initiation of antifungal therapy and management of complications are paramount to achieve remission of fungal disease in the setting of primary immunodeficiency disorders.

Recent advances in understanding inherited deficiencies in immunity to infections.

The immune system is central to our interactions with the world in which we live and importantly dictates our response to potential allergens, toxins, and pathogens to which we are constantly exposed. Understanding the mechanisms that underlie protective host immune responses against microbial pathogens is vital for the development of improved treatment and vaccination strategies against infections. To that end, inherited immunodeficiencies that manifest with susceptibility to bacterial, viral, and/or fungal infections have provided fundamental insights into the indispensable contribution of key immune pathways in host defense against various pathogens. In this mini-review, we summarize the findings from a series of recent publications in which inherited immunodeficiencies have helped illuminate the interplay of human immunity and resistance to infection.

Prophylactic Antibiotics Versus Immunoglobulin Replacement in Specific Antibody Deficiency.

PURPOSE: Prophylactic antibiotics (PA) and immunoglobulin replacement (IGRT) are commonly used in specific antibody deficiency (SAD); however, optimal treatment is not well-established. Our purpose is to compare treatment outcomes with IGRT and/or PA among SAD patients. METHODS: A retrospective chart review of SAD patients treated at two tertiary centers between January 2012 and May 2017 was performed. Clinical and laboratory data, and rates of infections prior to and after treatment with IGRT or PA were analyzed. Descriptive analyses, between-group comparisons of rates of infection after 1 year of treatment, and a stepwise logistic regression model were employed to explore factors contributing to treatment outcomes. RESULTS: We identified 65 SAD patients with mean age were 18 years (2-71 years). The baseline mean number of infections in the PA group and IGRT group was 4.71 (SD 3.15) and 7.73 (SD 6.65), respectively. Twenty-nine (44.6%) received IGRT, 7 (10.7%) received PA, 7 (10.7%) received both IGRT and PA, 15 (23.1%) failed PA and switched to IGRT, and 7 did not receive any specific treatment. After 1 year of treatment, the difference in the mean number of infections in PA vs. IGRT was not statistically significant [2.86 (2.73) vs. 4.44 (4.74), p = 0.27]. Reporting autoimmunity increased the odds for persistent infections (OR = 4.29; p = 0.047), while higher IgG levels decreased the odds for persistent infections (OR = 0.68, p = 0.018). CONCLUSIONS: PA and IGRT are equally effective as first line in preventing infections in SAD patients. However, patients who fail PA would benefit from IGRT.

Ascorbic acid-induced oxalate nephropathy: a case report and discussion of pathologic mechanisms.

Oxalate nephropathy is associated with hereditary hyperoxaluria, Crohn disease, and previous gastric or intestinal surgery, especially in the setting of increased oxalate intake or ethylene glycol ingestion. We present a patient whose intake of vitamin C supplements (2 g/day), exacerbated by predisposing factors of prior small bowel obstruction and resection, and benign prostate hyperplasia (BPH), resulted in acute kidney injury due to oxalate nephropathy. We review past reports of vitamin C-induced oxalate nephropathy and discuss the underlying precipitating factors.

Lessons from primary immunodeficiencies: Autoimmune regulator and autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy.

The discovery of the autoimmune regulator (AIRE) protein and the delineation of its critical contributions in the establishment of central immune tolerance has significantly expanded our understanding of the immunological mechanisms that protect from the development of autoimmune disease. The parallel identification and characterization of patient cohorts with the monogenic disorder autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), which is typically caused by biallelic AIRE mutations, has underscored the critical contribution of AIRE in fungal immune surveillance at mucosal surfaces and in prevention of multiorgan autoimmunity in humans. In this review, we synthesize the current clinical, genetic, molecular and immunological knowledge derived from basic studies in Aire-deficient animals and from APECED patient cohorts. We also outline major advances and research endeavors that show promise for informing improved diagnostic and therapeutic approaches for patients with APECED.

Combination Steroid and Test-based Food Elimination for Eosinophilic Esophagitis: A Retrospective Analysis.

OBJECTIVES: Eosinophilic esophagitis (EoE) is a clinicopathologic disorder characterized by infiltration of eosinophils into the esophagus. Primary treatment approaches include topical corticosteroids and/or food elimination. The aim of the present study was to compare the effectiveness of combination therapy (topical corticosteroid plus test-based food elimination [FS]) with single therapy (topical corticosteroid [S] or test-based food elimination [F]). METHODS: Chart review of patients with EoE at Texas Children's Hospital (age <21 years) was performed. Clinical and histological statuses were evaluated after a 3-month treatment with either single or combination therapy. Comparisons were analyzed using Fisher exact test, Kruskal-Wallis tests, and multiple logistic regression models. RESULTS: Among 670 charts, 63 patients (1-21 years, median 10.3 years) with clinicopathologic diagnoses of EoE were identified. Combination FS therapy was provided to 51% (n = 32) and single treatment (S, F) to 27% (n = 17) or 22% (n = 14) of patients, respectively. Clinical responses were noted in 91% (n = 29), 71% (n = 12), and 64% (n = 14) of patients in the FS, S, and F groups, respectively. The odds of clinically improving were 4.6 times greater (95% confidence interval: 1.1-18.8) with combination versus single therapy. The median peak number of eosinophils per high-power field after 3-month therapy was not significantly different in the S, F, and FS groups. CONCLUSIONS: The combination of topical corticosteroids with specific food elimination is as effective in achieving clinical and histological remissions as the single-treatment approaches. Responses were achieved with the combination in patients who had previously failed single-agent therapy. Prospective research of this combination approach in young patients with EoE is needed.