The phase 1/2 Harmony trial (NCT04856865) evaluated ADP101, a pharmaceutical-grade, investigational multifood oral immunotherapy (mOIT) for simultaneous treatment of allergy to 1-5 foods in ADP101 (almond, cashew, chicken's egg, codfish, cow's milk, hazelnut, peanut, pecan, pistachio, salmon, sesame, shrimp, soy, walnut, wheat). The primary analysis population (N=61) included children aged 4-17 years with qualifying allergy to 1-5 foods in ADP101 (dose-limiting symptoms to ≤100-mg on screening double-blind, placebo-controlled food challenge [DBPCFC]). Participants were randomized (2:2:1:1) to low-dose (100-mg protein/food/day; 1500-mg total/day) or high-dose ADP101 (300-mg protein/food/day; 4500-mg total/day) or low-dose/high-dose placebo for 40 weeks (up-dosing followed by dose-maintenance). Primary endpoint was the proportion of participants tolerating ≥600-mg of ≥1 qualifying food without dose-limiting symptoms at exit DBPCFC. Efficacy evaluation in multiallergic participants included tolerance of ≥600-mg and ≥1000-mg for ≥2 foods. Response to ADP101 was dose dependent (high-dose, 55%, low-dose, 38%, placebo, 20%), with high-dose ADP101 demonstrating a greater response rate than placebo (P=0.048, alpha=0.025). In multiallergic participants treated with high-dose ADP101, 55.6% were able to tolerate ≥600-mg of ≥2 qualifying foods (vs 0% of placebo-treated participants; P=0.006) and 44.4% tolerated ≥1000-mg of ≥2 foods (vs 0% of placebo-treated participants; P=0.021). Multiallergen efficacy observed within 40 weeks included desensitization to multiple non-cross-reactive foods. Adverse events were mostly mild or moderate, with no life-threatening events or deaths. Severe anaphylactic events were infrequent; none were attributed to ADP101. ADP101 demonstrated efficacy and a positive safety profile for desensitization of single and multiple food allergies in children.

Background and Aims: Tesnatilimab, a monoclonal antibody targeting NKG2D, was evaluated in Crohn's disease [CD] patients who had failed or were intolerant to biologic or conventional therapy. Methods: TRIDENT was a phase 2b, two-part, randomised, double-blind, placebo-controlled, parallel-arm, multicenter study. In Part 1 [proof of concept], 145 patients who were biologic intolerant or refractory [Bio-IR] or had not failed biologic therapy [Bio-NF] were randomised in a 1:1 ratio to placebo subcutaneously [SC] or tesnatilimab 400 mg SC. In Part 2 [dose ranging], 243 Bio-IR and Bio-NF patients were randomised in a 1:1:1:1:1 ratio to placebo, tesnatilimab [50 mg, 150 mg, 400 mg], or intravenous infusion of ustekinumab similar to 6 mg/kg at Week 0 and 90 mg SC at Weeks 8 and 16. The primary endpoint was mean change from baseline in Crohn's Disease Activity Index [CDAI] at Week 8 [Part 1] and Week 12 [Part 2]. Clinical and endoscopic remission/response were evaluated. Efficacy analyses were also assessed by NKG2D and MICB single nucleotide polymorphism [SNP] status [SNP-positive means positive in at least one of two SNPs]. Safety events were summarised. Results: In Part 1, mean change from baseline in CDAI score was significantly greater with tesnatilimab vs placebo at Week 8 [-103.6 vs -60.0; p < 0.01]. In Part 2, no dose-response signal was detected. Mean changes from baseline in CDAI at Week 12 were -93.2, -72.2, and -84.3 for low, middle, and high doses of tesnatilimab, respectively, vs -59.2 for placebo and -148.8 for ustekinumab. Similar reductions from baseline in CDAI score were observed in patients receiving tesnatilimab, regardless of SNP status. Clinical remission rates were greater with tesnatilimab than placebo in Parts 1 and 2, whereas endoscopic response rates were greater with tesnatilimab only in Part 1. No unexpected safety events occurred. Conclusions: Tesnatilimab was well tolerated. The efficacy of tesnatilimab in patients with CD was significant for the primary endpoint in Part 1; however, no dose-response signal was detected for the primary endpoint in Part 2. Based on these inconsistent findings, tesnatilimab was not considered an effective treatment for patients with CD and no further development is planned.

Objectives This ongoing Phase-2, randomised, placebo-controlled, double-blind study evaluated the efficacy, safety and pharmacokinetics of intravenous belimumab in childhood-onset systemic lupus erythematosus (cSLE). Methods Patients (5 to 17 years) were randomised to belimumab 10 mg/kg intravenous or placebo every 4 weeks, plus standard SLE therapy. Primary endpoint: SLE Responder Index (SRI4) response rate (Week 52). Key major secondary endpoints: proportion of patients achieving the Paediatric Rheumatology International Trials Organisation/American College of Rheumatology (PRINTO/ACR) response using 50 and ‘30 alternative’ definitions (Week 52), and sustained response (Weeks 44 to 52) by SRI4 and Parent Global Assessment of well-being (Parent-global). Safety and pharmacokinetics were assessed. Study not powered for statistical testing. Results Ninety-three patients were randomised (belimumab, n=53; placebo, n=40). At Week 52, there were numerically more SRI4 responders with belimumab versus placebo (52.8% vs 43.6%; OR 1.49 (95% CI 0.64 to 3.46)). PRINTO/ACR 30 alternative (52.8% vs 27.5%; OR 2.92 (95% CI 1.19 to 7.17)) and PRINTO/ACR 50 (60.4% vs 35.0%; OR 2.74 (95% CI 1.15 to 6.54)) responses were more frequent with belimumab than placebo, as were sustained responses for SRI4 (belimumab, 43.4%; placebo, 41.0%; OR 1.08 (95% CI 0.46 to 2.52)) and Parent-global (belimumab, 59.1%; placebo, 33.3%; OR 3.49 (95% CI 1.23 to 9.91)). Serious adverse events were reported in 17.0% of belimumab patients and 35.0% of placebo patients; one death occurred (placebo). Week-52, geometric mean (95% CI) belimumab trough concentration was 56.2 (45.2 to 69.8) µg/mL. Conclusion The belimumab intravenous pharmacokinetics and benefit–risk profile in cSLE are consistent with adult belimumab studies and the 10 mg/kg every 4 weeks dose is appropriate. Trial registration number NCT01649765.

Background: Belimumab (BEL), a monoclonal antibody targeting the B-lymphocyte stimulator, is approved in adults with active systemic lupus erythematosus (SLE). This is the first clinical trial of belimumab in pediatric patients with childhood-onset SLE (cSLE). Objectives: PLUTO, a Phase 2, randomised, double-blind trial (BEL114055; NCT01649765), evaluated the efficacy, safety and pharmacokinetics (PK) of intravenous (IV) BEL vs placebo (PBO), plus standard of care (SoC), in cSLE. Methods: Patients with cSLE 5–17 years of age were randomised to BEL 10 mg/kg IV or PBO every 4 weeks, plus SoC. Primary endpoint: SRI4 at Week 52. Major secondary endpoints: PRINTO/ACR 30 and 50 cSLE evaluation criteria for improvement at Week 52; cSLE core response variables at Week 52; and sustained SRI4 and ParentGA (patient well-being) responses (Weeks 44–52). Other endpoints: components of SRI4 at Week 52; and frequency of severe flares using the modified SELENA-SLEDAI Flare Index. Safety and PK were assessed. Analyses were performed on the intent-to-treat population. The study was not powered to test for differences between groups; p-values were not calculated. Results: 93 patients were included (BEL, n=53; PBO, n=40). Groups (BEL vs PBO) were balanced at baseline for age (mean [standard deviation] 13.5 [2.59] vs 14.8 [2.17] years, respectively) and SELENA-SLEDAI score (10.3 [3.34] vs 10.4 [3.63], respectively). Compared with PBO, there were more SRI4 responders (including all 3 components of SRI4), and PRINTO/ACR 30 and 50 responders in the BEL group (Figure). Likewise, more BEL than PBO recipients had sustained improvement of SRI and patient well-being (ParentGA) (Figure). Changes in cSLE core response variables are shown in the Table. Severe flares were 62% less frequent with BEL vs PBO (hazard ratio 0.38 [95% CI 0.18, 0.82]). PK: BEL exposures in cSLE were similar to adult SLE studies. 9/53 (17%) BEL patients had ≥1 serious adverse event vs 14/40 (35%) PBO patients. One PBO patient died of acute pancreatitis. Conclusion: The benefit:risk profile of BEL IV plus SoC in cSLE is generally consistent with BEL in adult SLE. The 10 mg/kg IV dose used in adults may be an appropriate dose in cSLE. Acknowledgement: The authors would like to acknowledge all investigators (PRINTO, PRCSG and otherwise affiliated) for the PLUTO study. Study funded by GSK. Gosia Carless, PhD, Fishawack Indicia Ltd, UK, provided editorial assistance funded by GSK. Disclosure of Interests: Nicolino Ruperto Grant/research support from: The Gaslini Hospital, where NR works as full-time public employee, has received contributions (> 10.000 USD each) from the following industries in the last 3 years: BMS, Eli-Lilly, GlaxoSmithKline, F Hoffmann-La Roche, Janssen, Novartis, Pfizer, Sobi. This funding has been reinvested for the research activities of the hospital in a fully independent manner, without any commitment with third parties., Consultant for: Received honoraria for consultancies or speaker bureaus (< 10.000 USD each) from the following pharmaceutical companies in the past 3 years: Ablynx, AbbVie, Astrazeneca-Medimmune, Biogen, Boehringer, Bristol-Myers Squibb, Eli-Lilly, EMD Serono, GlaxoSmithKline, Hoffmann-La Roche, Janssen, Merck, Novartis, Pfizer, R-Pharma, SanofiServier, Sinergie, Sobi and Takeda., Speakers bureau: Received honoraria for consultancies or speaker bureaus (< 10.000 USD each) from the following pharmaceutical companies in the past 3 years: Ablynx, AbbVie, Astrazeneca-Medimmune, Biogen, Boehringer, Bristol-Myers Squibb, Eli-Lilly, EMD Serono, GlaxoSmithKline, Hoffmann-La Roche, Janssen, Merck, Novartis, Pfizer, R-Pharma, SanofiServier, Sinergie, Sobi and Takeda., Carlos Abud-Mendoza: None declared, Diego O Viola: None declared, Inmaculada Calvo Grant/research support from: received research grants from Pfizer, Roche, Novartis, Clementia, Sanofi, MSD, BMS and GSK, Consultant for: Advisory boards: Novartis, AbbVie, Speakers bureau: AbbVie, Roche, Novartis, SOBI, Deborah M Levy Consultant for: received consulting fees and/or honoraria from AbbVie and Janssen, Julia Calderon Gallegos: None declared, Manuel Ferrandiz: None declared, Vyacheslav Chasnyk: None declared, Vladimir Keltsev: None declared, Jordi Anton Grant/research support from: JA has received grant/research support, consulting fees and/or honoraria from AbbVie, Alexion, BMS, ChemoCentryx, Gebro, GSK, Novartis, Novimmune, Pfizer, Roche, Sanofi and Sobi, Consultant for: JA has received grant/research support, consulting fees and/or honoraria from AbbVie, Alexion, BMS, ChemoCentryx, Gebro, GSK, Novartis, Novimmune, Pfizer, Roche, Sanofi and Sobi, Maria Gastanaga: None declared, Michael Shishov: None declared, Alina Boteanu: None declared, Michael Henrickson: None declared, Damon Bass Shareholder of: GSK, Employee of: GSK, Ken Clark Shareholder of: GSK, Employee of: GSK, Anne Hammer Shareholder of: GSK, Employee of: GSK, Beulah Ji Shareholder of: GSK, Employee of: GSK, Antonio Nino Shareholder of: GSK, Employee of: GSK, David Roth Shareholder of: GSK, Employee of: GSK, Herbert Struemper Shareholder of: GSK, Employee of: GSK, Mei-Lun Wang Employee of: former employee of GSK, Alberto Martini Consultant for: I do not have any conflict of interest to declare since starting from 1 March 2016 I became the Scientific Director of the G. Gaslini Hospital; therefore, my role does not allow me to render private consultancies resulting in personal income. I perform consultancy activities on behalf of the Gaslini Institute for the companies listed below: AbbVie, Biogen, Boehringer Ingelheim, Bristol-Myers Squibb, EMD Serono, Janssen, Novartis, Pfizer, R-Pharm. The money received for these activities are directly transferred to the Gaslini Institute’s bank account. Before March 2016, I was the head of the Pediatric Rheumatology Department at the G. Gaslini Hospital, where the PRINTO Coordinating Centre is located. For the coordination activity of the PRINTO network, the Gaslini Hospital received contributions from the industries listed in this section. This money has been reinvested for the research activities of the hospital in fully independent manners besides any commitment with third parties., Daniel J Lovell Consultant for: Consulting fees and/or honoraria from Astra Zeneca, Wyeth Pharma, Amgen, Abbott, Pfizer, F. Hoffmann-La Roche, Novartis, UBC, Takeda, GSK, Boehringer, and Celgene, Hermine Brunner Grant/research support from: Bristol-Myers Squibb, Pfizer, Consultant for: Pfizer, Bristol-Myers Squibb, Janssen, Novartis, Lilly, Roche, GlaxoSmithKline, Sanofi, Speakers bureau: Novartis, Roche

OBJECTIVE:This extension study of the Phase III, randomized, placebo-controlled Belimumab International SLE Study (BLISS)-52 and BLISS-76 studies allowed non-US patients with SLE to continue belimumab treatment, in order to evaluate its long-term safety and tolerability including organ damage accrual.METHODS:In this multicentre, long-term extension study (GlaxoSmithKline Study BEL112234) patients received i.v. belimumab every 4 weeks plus standard therapy. Adverse events (AEs) were assessed monthly and safety-associated laboratory parameters were assessed at regular intervals. Organ damage (SLICC/ACR Damage Index) was assessed every 48 weeks. The study continued until belimumab was commercially available, with a subsequent 8-week follow-up period.RESULTS:A total of 738 patients entered the extension study and 735/738 (99.6%) received one or more doses of belimumab. Annual incidence of AEs, including serious and severe AEs, remained stable or declined over time. Sixty-nine (9.4%) patients experienced an AE resulting in discontinuation of belimumab or withdrawal from the study. Eleven deaths occurred (and two during post-treatment follow-up), including one (cardiogenic shock) considered possibly related to belimumab. Laboratory parameters generally remained stable. The mean (s.d.) SLICC/ACR Damage Index score was 0.6 (1.02) at baseline (prior to the first dose of belimumab) and remained stable. At study year 8, 57/65 (87.7%) patients had no change in SLICC/ACR Damage Index score from baseline, indicating low organ damage accrual.CONCLUSION:Belimumab displayed a stable safety profile with no new safety signals. There was minimal organ damage progression over 8 years.TRIAL REGISTRATION:ClinicalTrials.gov, https://clinicaltrials.gov, NCT00424476 (BLISS-52), NCT00410384 (BLISS-76), NCT00732940 (BEL112232), NCT00712933 (BEL112234).

We read the article by Molina-Infante et al 1 with great concern as it proposes a major change in the current practice guidelines for managing patients presenting for care by gastroenterologists worldwide. Proton pump inhibitor-responsive oesophageal eosinophilia (PPI-REE)1 is characterised by an eosinophilic infiltrate of the oesophageal epithelium that is responsive to PPI therapy alone. The authors suggest that endoscopies should be performed prior to a therapeutic trial of PPI, so as not to miss this subtype of eosinophilic oesophagitis (EoE). We maintain that these two entities not only have yet to be proven to be the same pathophysiological process, but also that performing an initial endoscopy with biopsy would not change the current practice of first using a PPI before or after the …

GSK2982772 is a highly selective inhibitor of receptor‐interacting protein kinase 1 (RIPK1) being developed to treat chronic inflammatory diseases. This first‐in‐human study evaluated safety, tolerability, pharmacokinetics (PK), and exploratory pharmacodynamics (PD) of GSK2982772 administered orally to healthy male volunteers. This was a Phase I, randomized, placebo‐controlled, double‐blind study. In Part A, subjects received single ascending doses of GSK2982772 (0.1‐120 mg) or placebo in a crossover design during each of 4 treatment periods. In Part B, subjects received repeat doses of GSK2982772 (20 mg once daily [QD] to up to 120 mg twice daily [BID]) or placebo for 14 days. Part C was an open‐label relative bioavailability study comparing 20‐mg tablets vs capsules. Safety, tolerability, pharmacokinetics (PK), RIPK1 target engagement (TE), and pharmacodynamics (PD) were assessed. The most common adverse events (AEs) were contact dermatitis and headache. Most AEs were mild in intensity, and there were no deaths or serious AEs. The PK of GSK2982772 was approximately linear over the dose range studied (up to 120 mg BID). There was no evidence of drug accumulation upon repeat dosing. Greater than 90% RIPK1 TE was achieved over a 24‐hour period for the 60‐mg and 120‐mg BID dosing regimens. Single and repeat doses of GSK2982772 were safe and well tolerated. PK profiles showed dose linearity. The high levels of RIPK1 TE support progression into Phase II clinical trials for further clinical development.

Eosinophilic esophagitis (EoE) is a chronic Th2 and food antigen-mediated disease characterized by esophageal eosinophilic infiltration. Thymic stromal lymphopoetin (TSLP), an epithelial derived cytokine which bridges innate and Th2-type adaptive immune responses in other allergic conditions, is overexpressed in esophageal biopsies of EoE subjects. However, the triggers of TSLP expression in the esophageal epithelium are unknown. The objective of the current study was to characterize TSLP expression in human esophageal epithelium in EoE in vivo and to determine the role of food antigens upon epithelial TSLP expression in vitro. Using immunohistochemistry (IHC), we localized TSLP in esophageal biopsies of active EoE (≥15 eos/hpf), inactive EoE (<15 eos/hpf) and non-EoE control subjects, and found that TSLP expression was restricted to the differentiated suprabasal layer of the epithelium in actively inflamed EoE biopsies. Consistent with these results in vivo, inducible TSLP protein secretion was higher in CaCl2 differentiated telomerase-immortalized esophageal epithelial cells (EPC2-hTERT) compared to undifferentiated cells of the basal phenotype, following stimulation with the TLR3 ligand poly(I:C). To determine whether food antigens could directly induce epithelial TSLP secretion, differentiated and undifferentiated primary esophageal epithelial cells from EoE and non-EoE subjects were challenged with food antigens clinically relevant to EoE: Chicken egg ovalbumin (OVA), wheat, and milk proteins beta-lactoglobulin (blg) and beta-casein. Food antigens failed to induce TSLP secretion by undifferentiated cells; in contrast, only OVA induced TSLP secretion in differentiated epithelial cells from both EoE and control cell lines, an effect abolished by budesonide and NF-κb inhibition. Together, our study shows that specific food antigens can trigger innate immune mediated esophageal TSLP secretion, suggesting that esophageal epithelial cells at the barrier surface may play a significant role in the pathogenesis of EoE by regulating TSLP expression.

Merves, Jamie F MD1,2; Whelan, Kelly A PhD3,4; Benitez, Alain J MD1; Muir, Amanda B MD1,2; Furuta, Glenn T MD5; Wang, Mei-Lun MD1,2; Falk, Gary W MD, MS3; Spergel, Jonathan M MD, PhD2,6; Nakagawa, Hiroshi MD, PhD3,4 Author Information

We read the article by Molina-Infante et al 1 with great concern as it proposes a major change in the current practice guidelines for managing patients presenting for care by gastroenterologists worldwide. Proton pump inhibitor-responsive oesophageal eosinophilia (PPI-REE)1 is characterised by an eosinophilic infiltrate of the oesophageal epithelium that is responsive to PPI therapy alone. The authors suggest that endoscopies should be performed prior to a therapeutic trial of PPI, so as not to miss this subtype of eosinophilic oesophagitis (EoE). We maintain that these two entities not only have yet to be proven to be the same pathophysiological process, but also that performing an initial endoscopy with biopsy would not change the current practice of first using a PPI before or after the …

ObjectiveThe influence of eosinophilic oesophagitis (EoE)-associated inflammation upon oesophageal epithelial biology remains poorly understood. We investigated the functional role of autophagy in oesophageal epithelial cells (keratinocytes) exposed to the inflammatory EoE milieu.DesignFunctional consequences of genetic or pharmacological autophagy inhibition were assessed in endoscopic oesophageal biopsies, human oesophageal keratinocytes, single cell-derived ex vivo murine oesophageal organoids as well as a murine model recapitulating EoE-like inflammation and basal cell hyperplasia. Gene expression, morphological and functional characterisation of autophagy and oxidative stress were performed by transmission electron microscopy, immunostaining, immunoblotting, live cell imaging and flow cytometry.ResultsEoE-relevant inflammatory conditions promoted autophagy and basal cell hyperplasia in three independent murine EoE models and oesophageal organoids. Inhibition of autophagic flux via chloroquine treatment augmented basal cell hyperplasia in these model systems. Oesophageal keratinocytes stimulated with EoE-relevant cytokines, including tumour necrosis factor-α and interleukin-13 exhibited activation of autophagic flux in a reactive oxygen species-dependent manner. Autophagy inhibition via chloroquine treatment or depletion of Beclin-1 or ATG-7, augmented oxidative stress induced by EoE-relevant stimuli in murine EoE, oesophageal organoids and human oesophageal keratinocytes. Oesophageal epithelia of paediatric EoE patients with active inflammation displayed increased autophagic vesicle content compared with normal and EoE remission subjects. Functional flow cytometric analysis revealed autophagic flux in human oesophageal biopsies.ConclusionsOur findings reveal for the first time that autophagy may function as a cytoprotective mechanism to maintain epithelial redox balance and homeostasis under EoE inflammation-associated stress, providing mechanistic insights into the role of autophagy in EoE pathogenesis.

ABSTRACTObjectives:Eosinophilic esophagitis (EoE) is an immune‐mediated allergic disease characterized by progressive esophageal dysmotility and fibrotic stricture associated with chronic esophageal fibroblast activation. It remains unknown how esophageal fibroblasts respond to EoE‐relevant matrix stiffness or inflammatory cytokines.Methods:Immunofluorescence was used to evaluate α‐smooth muscle actin (α‐SMA) expression in endoscopic esophageal biopsies. Primary esophageal fibroblasts from adult and pediatric patients with or without EoE were exposed to transforming growth factor (TGF)β to determine gene expression, collagen‐matrix contractility, and cytoskeletal organization. The influence of matrix stiffness upon fibroblast behavior was assessed on the engineered surface of polyacrylamide gels with varying stiffness. Fibroblast traction forces were measured using microfabricated‐post‐array‐detectors.Results:EoE esophageal fibroblasts had enhanced α‐SMA expression. TGFβ not only stimulated enhanced fibroblast‐specific gene expression but also promoted fibroblast‐mediated collagen‐matrix contraction, despite disease state or age of patients as the origin of cells. Unlike conventional monolayer cell, culture conditions using plastic surface (1 GPa) that activates fibroblasts constitutively, our engineered platforms recapitulating physiologically relevant stiffness (1–20 kPa) revealed that matrix stiffness defines the extent of α‐SMA expression, intracellular collagen fibril organization, SMAD3 phosphorylation, and fibroblast traction force.Conclusions:Matrix stiffness may critically influence TGFβ‐mediated gene expression and functions of esophageal fibroblasts ex vivo independent of age and disease conditions. These findings provide a novel insight into the pathogenesis of fibrostenotic disease in EoE.

Tissue homeostasis requires balanced self-renewal and differentiation of stem/progenitor cells, especially in tissues that are constantly replenished like the esophagus. Disruption of this balance is associated with pathological conditions, including eosinophilic esophagitis (EoE), in which basal progenitor cells become hyperplastic upon proinflammatory stimulation. However, how basal cells respond to the inflammatory environment at the molecular level remains undetermined. We previously reported that the bone morphogenetic protein (BMP) signaling pathway is critical for epithelial morphogenesis in the embryonic esophagus. Here, we address how this pathway regulates tissue homeostasis and EoE development in the adult esophagus. BMP signaling was specifically activated in differentiated squamous epithelium, but not in basal progenitor cells, which express the BMP antagonist follistatin. Previous reports indicate that increased BMP activity promotes Barrett's intestinal differentiation; however, in mice, basal progenitor cell-specific expression of constitutively active BMP promoted squamous differentiation. Moreover, BMP activation increased intracellular ROS levels, initiating an NRF2-mediated oxidative response during basal progenitor cell differentiation. In both a mouse EoE model and human biopsies, reduced squamous differentiation was associated with high levels of follistatin and disrupted BMP/NRF2 pathways. We therefore propose a model in which normal squamous differentiation of basal progenitor cells is mediated by BMP-driven NRF2 activation and basal cell hyperplasia is promoted by disruption of BMP signaling in EoE.

of SBI in a pediatric patient with an acute diarrhea due to SIBO and/or antibiotic therapy. SBI may prove to be useful in some acute setting where limited therapeutic options are available. Given that SBI has been designated as a medical food with GRAS (General Recognized As Safe) status for use in the general population, it may serve as an option for children in the nutritional management of chronic loose and frequent stools.

Eosinophilic Esophagitis (EoE) is a chronic allergic disorder, whose pathobiology is incompletely understood. Histamine-producing cells including mast cells and basophils have been implicated in EoE. However, very little is currently known about the role of histamine and histamine receptor (HR) expression and signaling in the esophageal epithelium. Herein, we characterized HR (H1R, H2R, H3R, and H4R) expression in human esophageal biopsies and investigate the role of histamine signaling in inducible cytokine expression in human esophageal epithelial cells in vitro. HR expression was quantified in esophageal biopsies from non-EoE control (N = 23), inactive EoE (<15 eos/hpf, N = 26) and active EoE (>15 eos/hpf, N = 22) subjects using qRT-PCR and immunofluorescent localization. HR expression and histamine-mediated cytokine secretion were evaluated in human primary and telomerase-immortalized esophageal epithelial cells. H1R, H2R, and H4R expression were increased in active EoE biopsies compared to inactive EoE and controls. H2R was the most abundantly expressed receptor, and H3R expression was negligible in all 3 cohorts. Infiltrating eosinophils expressed H1R, H2R, and H4R, which contributed to the observed increase in HR in active subjects. H1R and H2R, but not H3R or H4R, were constitutively expressed by primary and immortalized cells, and epithelial histamine stimulation induced GM-CSF, TNFα, and IL-8, but not TSLP or eotaxin-3 secretion. Epithelial priming with the TLR3 ligand poly (I:C) induced H1R and H2R expression, and enhanced histamine-induced GM-CSF, TNFα, and IL-8 secretion. These effects were primarily suppressed by H1R antagonists, but unaffected by H2R antagonism. Histamine directly activates esophageal epithelial cytokine secretion in vitro in an H1R dependent fashion. However, H1R, H2R and H4R are induced in active inflammation in EoE in vivo. While systemic antihistamine (anti-H1R) therapy may not induce clinical remission in EoE, our study suggests that further study of histamine receptor signaling in EoE is warranted and that targeting of additional histamine receptors may lead to novel treatment strategies for this important disease.