Masuda, Mia Y.

Abstract Introduction Environmental exposure to food allergens (e.g. peanut antigens) through the skin or airways increases the risk of developing food allergy (e.g. peanut allergy). In contrast, oral antigen exposure (e.g., consumption of peanut products) early in life reduces the risk. The objective of this study was to investigate the immunologic mechanisms by which oral antigen exposure provides systemic immunotolerance and protection from food allergy development using murine models. Methods Naive mice were administered ovalbumin (OVA) through their drinking water to promote oral immunotolerance. Mice were subsequently exposed intranasally (i.n.) to OVA plus peanut flour, as an allergic adjuvant. CD4+ T cells from lung draining lymph nodes (dLNs) were assessed by single-cell RNA sequencing, MHC-II tetramer staining, and flow cytometry. Results Following i.n. exposure to OVA plus peanut flour, mice developed OVA-specific IgE (OVA-IgE) and showed symptoms of acute anaphylaxis upon intraperitoneal OVA challenge. Oral OVA feeding prior to i.n. OVA exposure reduced OVA-IgE and protected mice from anaphylaxis. Protection was associated with suppression of OVA-specific T follicular helper (Tfh) and germinal center B cells in dLNs. Tolerance was reversed by administration of anti-CTLA-4 blocking antibody but was not affected by deletion of Foxp3+Bcl6+ T follicular regulatory (Tfr) cells. Accordingly, conventional Foxp3+T regulatory (Treg) cells were not increased in dLNs of OVA-fed mice. Rather, protection was associated with the emergence of OVA-specific Foxp3-CTLA4+ cells expressing markers of stemness. Conclusion Oral antigen exposure suppresses the development of antigen-specific Tfh cells in remote dLNs thereby preventing systemic allergic sensitization. Systemic oral tolerance is dependent on CTLA-4 and unlikely requires conventional Foxp3+ Treg cells. Funding Source Supported by NIH F31 AI86242, R37 AI71106, and Mayo Clinic Graduate School of Biomedical Sciences. Topic Categories Immediate Hypersensitivity, Asthma, and Allergic Responses (HYP)

ABSTRACT Background Eosinophilic esophagitis is associated with epithelial barrier dysfunction. Epidemiologic studies suggest environmental factors promote disease pathogenesis. The common household detergent sodium dodecyl sulfate (SDS) induces epithelial barrier dysfunction and eosinophilic inflammation in mice. We hypothesized that acute SDS exposure would compromise the esophageal mucosal barrier in humans. Methods Healthy adults brushed with 2 g of an SDS‐containing toothpaste. Esophageal impedance was measured continuously pre‐/post‐toothbrushing to assess the effect of toothpaste on epithelial barrier function. SDS was measured in saliva using a methylene blue anionic substances assay. Participants completed 1‐h esophageal string tests (ESTs) pre‐/post‐toothbrushing and protein isolates from EST eluates from the proximal and distal esophagus were analyzed by tandem mass tag mass spectrometry. Results Ten of twelve subjects completed the clinical study. SDS in the initial expectorate measured immediately after toothbrushing varied markedly (median: 321.40 μg/mL; range: 169.90–1243.00 μg/mL) and was detectable in saliva in 80% of subjects (median: 9.55 μg/mL; range: 0–123.40 μg/mL) at 60 min post toothbrushing. Esophageal mucosal impedance decreased within 30 min of toothbrushing ( p < 0.01). Toothbrushing increased salivary viscosity and proteins associated with mucosal defense in EST eluates. The tight junction pathway was downregulated while the salivary secretion and complement and coagulation cascades pathways were upregulated in the proximal esophagus. Conclusion In healthy individuals, SDS remained detectable in saliva for a prolonged period after toothbrushing at concentrations previously shown to disrupt esophageal epithelial barrier function in vitro. Toothbrushing with an SDS‐containing toothpaste was associated with reduced esophageal mucosal impedance, altered salivary properties, and activated mucosal immune responses.

Abstract Description Early oral route antigen exposure decreases the incidence of food allergy while environmental exposures through non-oral routes, such as the skin or airways, increase the risk. The goal of this study was to investigate the immunologic mechanisms of how oral allergen consumption protects from sensitization to the same allergens through environmental exposure routes. Naive mice were orally administered ovalbumin (OVA) in drinking water. Mice were subsequently exposed intranasally (i.n.) or epicutaneously (e.c.) to OVA plus peanut flour, as an adjuvant. OVA-specific CD4+ T cells from draining lymph nodes (dLNs) were assessed by MHC-II tetramer staining and flow cytometry. Following i.n. or e.c. exposure to OVA plus peanut flour, mice developed OVA-IgE and OVA-IgG1 and showed symptoms of acute anaphylaxis upon OVA challenge. Oral OVA feeding prior to i.n. or e.c. antigen exposure dramatically reduced OVA-IgE titers and protected mice from anaphylaxis. Protection was OVA-specific, as OVA-fed mice still developed peanut-IgE and anaphylaxis upon i.p. peanut challenge. Total OVA-specific CD4+ T and CD4+Foxp3+ T regulatory (Treg) cell numbers in dLNs were similar between control and OVA-fed mice. However, the majority of OVA-specific CD4+ T cells in control dLNs were T follicular helper (Tfh) cells, which were nearly abolished in OVA-fed mice. Oral route antigen exposure suppresses development of antigen-specific Tfh cells in remote dLNs and prevents systemic allergic sensitization. Funding Sources Supported by NIH R37 AI71106 and Mayo Clinic Graduate School of Biomedical Sciences. Topic Categories Immediate Hypersensitivity, Asthma, and Allergic Responses (HYP)

BACKGROUND Obesity is a multifactorial disease with adverse health implications including insulin resistance (IR). In patients with obesity, the presence of high circulating levels of leptin, deemed hyperleptinemia, is associated with IR. Recent data in mice with diet-induced obesity (DIO) show that a partial reduction in leptin levels improves IR. Additional animal studies demonstrate that IL-4 decreases leptin levels. In rodents, resident adipose tissue eosinophils (AT-EOS) are the main source of IL-4 and are instrumental in maintaining metabolic homeostasis. A marked reduction in AT-EOS content is observed in animal models of DIO. These observations have not been explored in humans. METHODS We analyzed AT from individuals with obesity and age-matched lean counterparts for AT-EOS content, IL-4, circulating leptin levels, and measures of IR. RESULTS Our results show that individuals with obesity ( n = 15) had a significant reduction in AT-EOS content ( P < 0.01), decreased AT–IL-4 gene expression ( P = 0.02), and decreased IL-4 plasma levels ( P < 0.05) in addition to expected IR ( P < 0.001) and hyperleptinemia ( P < 0.01) compared with lean subjects ( n = 15). AT-EOS content inversely correlated with BMI ( P = 0.002) and IR ( P = 0.005). Ex vivo AT explants and in vitro cell culture of primary human mature adipocytes exposed to either IL-4 or EOS conditioned media produced less leptin ( P < 0.05). CONCLUSION Our results suggest that IL-4 acts as a link between EOS, AT, and leptin production. Future studies exploring this interaction may identify an avenue for the treatment of obesity and its complications through amelioration of hyperleptinemia. TRIAL REGISTRATION Clinicaltrials.gov NCT02378077 & NCT04234295.

INTRODUCTION: We aimed to assess the diagnostic utility of eosinophil peroxidase (EPX) staining on Cytosponge (CS) samples in eosinophilic esophagitis (EoE). METHODS: Esophageal biopsy (BX) samples from adult subjects with EoE were assessed using peak eosinophils per high-power field (eos/hpf), EPX, and the EoE histologic scoring system. EPX staining and eos/hpf were compared (BX vs CS). RESULTS: CS EPX positivity correlated with eos/hpf (CS [ r = 0.82, P < 0.0001]; BX [ r = 0.65, P < 0.0001]) and EoE histologic scoring system (grade [ r = 0.62, P < 0.00001]; stage [ r = 0.61, P < 0.0001]). CS EPX identified subjects with active EoE (area under the curve = 0.86, P < 0.0001). DISCUSSION: The correlation of CS EPX with eosinophilic inflammation and histologic disease severity supports its diagnostic utility in EoE.

AbstractBackgroundEosinophilic esophagitis (EoE) is a chronic allergic disease associated with type 2 inflammation and epithelial barrier dysfunction. The etiology is unknown, however, genetic heritability studies suggest environmental factors play a key role in pathogenesis. Detergents, such as sodium dodecyl sulfate (SDS), are common ingredients in household products such as dish soap and toothpaste. We hypothesized detergent exposure decreases epithelial barrier function and induces esophageal inflammation.MethodsImmortalized esophageal epithelial cells (EPC2) were cultured in air‐liquid interface (ALI) and exposed to SDS. Barrier function/activity was assessed by transepithelial electrical resistance (TEER), FITC‐dextran flux, and RT‐PCR. Additionally, SDS‐treated mouse esophageal organoids were evaluated for morphology. To investigate the effects of SDS in vivo, mice were treated with 0.5% SDS in drinking water for 14 days. Esophagi were assessed by gross morphology, histopathology, protein expression, and bulk RNA sequencing.ResultsWhen EPC2 cells were exposed to SDS (5 μg/ml) for 96 h, TEER decreased (p = 0.03), and FITC‐dextran flux increased (p = 0.0002). mRNA expression of IL‐33 increased 4.5‐fold (p = 0.02) at 6 h and DSG1 decreased (p < 0.0001) by 72 h. Disrupted epithelial integrity was noted in SDS‐treated esophageal organoids. When mice were exposed to SDS, they showed increased esophageal width, chemokine, and metalloprotease levels. Mice treated with SDS also showed increased IL‐33 protein expression, basal zone hyperplasia, CD4+ cell infiltration, and esophageal eosinophilia. RNA sequencing revealed upregulation of immune response pathway genes.ConclusionExposure to SDS decreases esophageal barrier integrity, stimulates IL‐33 production, and promotes epithelial hyperplasia and tissue eosinophilia. Detergents may be a key environmental trigger in EoE pathogenesis.

Abstract A novel role for adipose tissue (AT)-resident eosinophils (EOS) in metabolism has been suggested. These data were obtained using genetic animal models with either whole-body overexpression of Interleukin-5 (IL-5Tg) leading to eosinophilia or gene ablation resulting in complete lack of EOS. These models limit the specificity of the findings. We hypothesized that AT-resident EOS play a specific role in whole-body metabolism. To this end, we generated a transgenic mouse model overexpressing human eotaxin-2 (hE2) under the control of a fat-specific aP2 promoter, which would exclusively recruit circulating EOS into AT (hEo2Tg), without any changes in the overall EOS numbers. Compared with wild type (WT) mice, AT-EOS numbers were markedly increased in multiple fat depots from hEo2Tg mice, including subcutaneous white adipose tissue (sWAT). After 12 weeks of high-fat diet (HFD), hEo2Tg mice showed significantly less body weight gain and fat mass compared with WT littermates. These changes were associated with an improvement in glucose tolerance. We also found increased oxygen consumption and heat production in hEo2Tg mice under room temperature conditions. The increased thermogenesis was accompanied with an increased expression of browning genes such as Ucp1, Prdm16, Dio2 in sWAT from hEo2Tg HFD mice. So far, our data suggest that AT-resident EOS promote browning of sWAT. This, in turn, protects our animals against development of HFD-induced obesity and insulin resistance. Next, whole transcriptome mRNA sequencing and bioinformatic analyses were performed and showed a significant increase of myogenic differentiation 1 (Myod1) gene expression in hEo2Tg sWAT mice. This was confirmed by qRT-PCR. Myod1 is a key regulator of skeletal muscle differentiation. Given the shared features between brown fat and skeletal muscle, we speculate that by increasing Myod1 gene expression, (AT)-resident EOS mediate sWAT browning. Additional studies are needed to determine the molecular mechanism(s) underling the regulation of Myod1 gene expression by AT-resident EOS and its effect on sWAT browning.