Title: Biological therapies for eosinophilic gastrointestinal diseases
Abstract: The scientific basis and the clinical application of mAb therapies that target specific immunologic pathways for eosinophilic gastrointestinal diseases are areas of active interest. There is a growing recognition of a subset of patients with eosinophilic esophagitis whose disease does not respond well to topical steroids or elimination diets. In addition, long-term use of corticosteroids presents possible risks that are currently being evaluated. Systemic therapy with a biologic agent offers potential advantages as a global approach that could limit the need for multiple, locally active medical therapies and allergen avoidance. The identification of novel biologic strategies is ongoing, and the recent validation of instruments and outcome measures to assess disease activity has proved essential in demonstrating efficacy. Studies using biologics that target IL-13 pathways in the treatment of eosinophilic esophagitis have demonstrated substantial promise. The scientific basis and the clinical application of mAb therapies that target specific immunologic pathways for eosinophilic gastrointestinal diseases are areas of active interest. There is a growing recognition of a subset of patients with eosinophilic esophagitis whose disease does not respond well to topical steroids or elimination diets. In addition, long-term use of corticosteroids presents possible risks that are currently being evaluated. Systemic therapy with a biologic agent offers potential advantages as a global approach that could limit the need for multiple, locally active medical therapies and allergen avoidance. The identification of novel biologic strategies is ongoing, and the recent validation of instruments and outcome measures to assess disease activity has proved essential in demonstrating efficacy. Studies using biologics that target IL-13 pathways in the treatment of eosinophilic esophagitis have demonstrated substantial promise. At present, our therapeutic options for eosinophilic esophagitis (EoE) include medications, elimination diets, and esophageal dilation. Medical therapeutics consist primarily of orally administered topical corticosteroids. Several randomized controlled trials support the efficacy of topical corticosteroids, although the histologic response rates have varied, ranging from 40% to 90%.1Dohil R. Newbury R. Fox L. Bastian J. Aceves S. Oral viscous budesonide is effective in children with eosinophilic esophagitis in a randomized, placebo-controlled trial.Gastroenterology. 2010; 139: 418-429Google Scholar, 2Moawad F.J. Veerappan G.R. Dias J.A. Baker T.P. Maydonovitch C.L. Wong R.K. Randomized controlled trial comparing aerosolized swallowed fluticasone to esomeprazole for esophageal eosinophilia.Am J Gastroenterol. 2013; 108: 366-372Google Scholar, 3Peterson K.A. Thomas K.L. Hilden K. Emerson L.L. Wills J.C. Fang J.C. Comparison of esomeprazole to aerosolized, swallowed fluticasone for eosinophilic esophagitis.Dig Dis Sci. 2010; 55: 1313-1319Google Scholar, 4Philpott H. Nandurkar S. Royce S.G. Thien F. Gibson P.R. A prospective open clinical trial of a proton pump inhibitor, elimination diet and/or budesonide for eosinophilic oesophagitis.Aliment Pharmacol Ther. 2016; 43: 985-993Google Scholar, 5Remedios M. Campbell C. Jones D.M. Kerlin P. Eosinophilic esophagitis in adults: clinical, endoscopic, histologic findings, and response to treatment with fluticasone propionate.Gastrointest Endosc. 2006; 63: 3-12Google Scholar, 6Teitelbaum J.E. Fox V.L. Twarog F.J. Nurko S. Antonioli D. Gleich G. et al.Eosinophilic esophagitis in children: immunopathological analysis and response to fluticasone propionate.Gastroenterology. 2002; 122: 1216-1225Google Scholar To date, however, topical corticosteroids are not approved by the Food and Drug Administration for the treatment of EoE. As a result, many clinicians are using preparations designed for asthma. A limited number of studies regarding long-term topical corticosteroid use have raised concerns regarding their effectiveness, particularly in the setting of attempts at dose reduction,7Andreae D.A. Hanna M.G. Magid M.S. Malerba S. Andreae M.H. Bagiella E. et al.Swallowed fluticasone propionate is an effective long-term maintenance therapy for children with eosinophilic esophagitis.Am J Gastroenterol. 2016; 111: 1187-1197Google Scholar, 8Straumann A. Conus S. Degen L. Frei C. Bussmann C. Beglinger C. et al.Long-term budesonide maintenance treatment is partially effective for patients with eosinophilic esophagitis.Clin Gastroenterol Hepatol. 2011; 9: 400-409.e1Google Scholar, 9Greuter T. Bussmann C. Safroneeva E. Schoepfer A.M. Biedermann L. Vavricka S.R. et al.Long-term treatment of eosinophilic esophagitis with swallowed topical corticosteroids: development and evaluation of a therapeutic concept.Am J Gastroenterol. 2017; 112: 1527-1535Google Scholar and long-term adverse effects such as adrenal insufficiency.10Golekoh M.C. Hornung L.N. Mukkada V.A. Khoury J.C. Putnam P.E. Backeljauw P.F. Adrenal insufficiency after chronic swallowed glucocorticoid therapy for eosinophilic esophagitis.J Pediatr. 2016; 170: 240-245Google Scholar For eosinophilic gastrointestinal diseases (EGIDs) that affect the stomach, small intestine, and colon, systemic corticosteroids are widely used with well-known adverse effects associated with prolonged administration.11Reed C. Woosley J.T. Dellon E.S. Clinical characteristics, treatment outcomes, and resource utilization in children and adults with eosinophilic gastroenteritis.Dig Liver Dis. 2015; 47: 197-201Google Scholar Biologic therapies introduce novel approaches that target specific immune pathways and potentially address several unmet needs in the management of EoE and EGIDs (Fig 1 and Table I). This review summarizes the therapeutic potential, scientific rationale, and available clinical trial data regarding past, present, and future biologic treatments.Table ITargets of therapy, role in pathogenesis, and associated pharmaceuticalsTargetRole in pathogenesisClinical trials in EGIDsClinical trials (atopic disease)Clinical trials (nonatopic disease)IL-5/IL5-RActivation and recruitment of eosinophilsMepolizumab, reslizumab, benralizumabMepolizumab, reslizumab, benralizumabMepolizumabIL-13Promote eosinophil recruitments, barrier dysfunction, remodelingQAX576, RPC4046TralokinumabTralokinumabIL-4RAMaintenance of TH2 inflammatory processDupilumabDupilumab, AMG 317CRTH2Recruitment of T cellsOC000459AZD1981, OC459, QAV680Siglec-8Induction of eosinophil cell deathInhibition of mast cell activationAK002AK001, AK002TSLPRecruitment of basophils, stimulation of IL-4 to promote TH2Tezepelumab (AMG 157)Integrin alpha4beta7Recruitment of T cells, eosinophils, and mast cellsVedolizumabEotaxin-1, -2, -3Recruitment of eosinophilsGW766994TGF-β1Enhance collagen production to promote fibrosisPromote smooth muscle contractionWorsen barrier integrityLosartanFresolimumab, losartan Open table in a new tab The interpretation of clinical trials of novel therapeutics in EGIDs relies on the application of appropriate and validated end points, and the lack of an accepted set of clinical outcome metrics for defining successful response to therapy impedes progress. Currently, focus lies on the coprimary end point of symptom assessment using patient-reported outcome (PRO) instruments and histologic assessment of peak mucosal eosinophil density (eosinophils [eos]/hpf). The tools used to assess symptoms and histopathology, however, have varied considerably and have been largely unvalidated. Over the past several years, several PRO instruments have been designed and validated for the evaluation of symptoms and quality of life in both pediatric and adult EoE. For adults, validated instruments include the Daily Symptom Questionnaire and EoE Activity Index.12Safroneeva E. Straumann A. Coslovsky M. Zwahlen M. Kuehni C.E. Panczak R. et al.Symptoms have modest accuracy in detecting endoscopic and histologic remission in adults with eosinophilic esophagitis.Gastroenterology. 2016; 150: 581-590.e4Google Scholar For children, the Pediatric EoE Symptom Score has been validated but it has not yet been evaluated in terms of patients' responsiveness to therapy.13Hirano I. Spechler S. Furuta G. Dellon E.S. White paper AGA: drug development for eosinophilic esophagitis.Clin Gastroenterol Hepatol. 2017; 15: 1173-1183Google Scholar Unfortunately, most of these validated tools were not available during the design of many clinical trials under current discussion. Although symptom assessment is a logical end point for trials in EoE, it is important to emphasize limitations to this measurement of outcome. Prolonged mastication, extended meal times, and avoidance of harder textured foods (eg, meat and bread) can mitigate the intensity of dysphagia and lead to inaccurate assessment of disease activity. Another major concern lies in the relationship between symptoms and esophageal remodeling. Esophageal remodeling related to chronic inflammation manifests as esophageal strictures that are a major determinant of symptom outcomes of dysphagia and food impaction.14Hirano I. Aceves S.S. Clinical implications and pathogenesis of esophageal remodeling in eosinophilic esophagitis.Gastroenterol Clin North Am. 2014; 43: 297-316Google Scholar The ability of anti-inflammatory or immune therapies to reverse fibrostenosis is unproven in EoE; thus, requiring such therapeutics to relieve dysphagia may overlook therapeutic benefits in preventing other disease consequences. The clinical observation that symptoms of dysphagia can be effectively ameliorated in more than 90% of patients with esophageal dilation, without altering the underlying inflammatory response, supports this view.15Schoepfer A.M. Gonsalves N. Bussmann C. Conus S. Simon H.U. Straumann A. et al.Esophageal dilation in eosinophilic esophagitis: effectiveness, safety, and impact on the underlying inflammation.Am J Gastroenterol. 2010; 105: 1062-1070Google Scholar Randomized controlled trials have demonstrated that measuring EoE activity using esophageal mucosal eosinophil density offers an objective and quantifiable measure with a high degree of interobserver agreement and with minimal placebo response. Outcomes are commonly defined by a reduction in mucosal eosinophilia, but the method used to calculate eosinophil density has varied considerably. Furthermore, various target thresholds have been used including end points of less than 15, less than 10, less than 6, and less than 5 eos/hpf in some studies and percent reduction in eosinophil density in others. The recent development and validation of an EoE Histologic Severity Score that incorporates histopathology beyond eosinophil density including basal cell hyperplasia, dilation of intercellular spaces, and subepithelial fibrosis provides a more comprehensive and accurate characterization of mucosal inflammation in EoE for clinical trials.16Collins M.H. Martin L.J. Alexander E.S. Boyd J.T. Sheridan R. He H. et al.Newly developed and validated eosinophilic esophagitis histology scoring system and evidence that it outperforms peak eosinophil count for disease diagnosis and monitoring.Dis Esophagus. 2017; 30: 1-8Google Scholar Although it is tempting to consider the use of histology as the primary determinant of therapeutic efficacy, a marked dissociation between symptoms and pathology is well recognized. This dissociation is likely explained by modification of eating behavior, subepithelial remodeling that is poorly assessed with standard biopsy technique, and a symptom-placebo response. Endoscopic outcomes serve as primary determinants of therapeutic efficacy in gastroesophageal reflux disease and inflammatory bowel disease, and increasing data support their use as an objective end point in clinical trials of EoE. The EoE Endoscopic REFerence Scoring system, or EREFS, is a classification and grading system that has been validated and shows a high degree of accuracy in the diagnosis of EoE in children and adults.13Hirano I. Spechler S. Furuta G. Dellon E.S. White paper AGA: drug development for eosinophilic esophagitis.Clin Gastroenterol Hepatol. 2017; 15: 1173-1183Google Scholar, 17Hirano I. Moy N. Heckman M.G. Thomas C.S. Gonsalves N. Achem S.R. Endoscopic assessment of the oesophageal features of eosinophilic oesophagitis: validation of a novel classification and grading system.Gut. 2013; 62: 489-495Google Scholar, 18Wechsler J.B. Bolton S. Amsden K. Wershil B.K. Hirano I. Kagalwalla A.F. Eosinophilic esophagitis reference score accurately identifies disease activity and treatment effects in children.Clin Gastroenterol Hepatol. 2017; ([Epub ahead of print])https://doi.org/10.1016/j.cgh.2017.12.019Google Scholar Recent clinical trials of topical steroids optimized for esophageal delivery as well as phase 2 trials of biologic therapies have demonstrated responsiveness of EREFS in assessment of mucosal healing.19Dellon E.S. Katzka D.A. Collins M.H. Hamdani M. Gupta S.K. Hirano I. et al.Budesonide oral suspension improves symptomatic, endoscopic, and histologic parameters compared with placebo in patients with eosinophilic esophagitis.Gastroenterology. 2017; 152: 776-786.e5Google Scholar, 20Hirano I. Collins M.H. Assouline-Dayan Y. Evans L. Gupta S.K. Schoepfer A. et al.A randomized, double-blind, placebo-controlled trial of a novel recombinant, humanized, anti-interleukin-13 monoclonal antibody (RPC4046) in patients with active eosinophilic esophagitis: results of the HEROES study. United Eur Gastroenterol Week. October, Vienna, Austria2016Google Scholar, 21Hirano I. Dellon E.S. Hamilton J.D. Collins M.H. Peterson K.A. Chehade M. et al.Dupilumab efficacy and safety in adult patients with active eosinophilic esophagitis: a randomized double-blind placebo-controlled phase 2 trial. Presented at: American College of Gastroenterology National Meeting. October, Orlando (FL)2017Google Scholar Other investigations are actively evaluating biomarkers of EoE disease activity beyond mucosal healing and symptoms. mRNA expression provides a molecular fingerprint of key upregulated and downregulated genes in esophageal biopsies of EoE that is distinct from the signature identified in control subjects and patients with gastroesophageal reflux disease.22Wen T. Stucke E.M. Grotjan T.M. Kemme K.A. Abonia J.P. Putnam P.E. et al.Molecular diagnosis of eosinophilic esophagitis by gene expression profiling.Gastroenterology. 2013; 145: 1289-1299Google Scholar The Eosinophil Diagnostic Panel includes clusters of genes that depict TH2 inflammatory response, mast cell activation, and fibrosis pathways. Reversal of the EoE pattern has been demonstrated in the setting of randomized controlled trials using topical fluticasone in children and anti–IL-13 therapy in adults. The Eosinophil Diagnostic Panel offers potential for examining molecular pathways that may provide insights into EoE pathogenesis, inform a personalized approach to therapy, and improve diagnostic accuracy. For whole-organ assessment of esophageal remodeling, the functional lumen imaging probe is a catheter-based technique performed during an endoscopic examination that applies impedance planimetry to measure esophageal biomechanical properties in EoE.23Hirano I. Pandolfino J.E. Boeckxstaens G.E. Functional lumen imaging probe for the management of esophageal disorders: expert review from the Clinical Practice Updates Committee of the AGA Institute.Clin Gastroenterol Hepatol. 2017; 15: 325-334Google Scholar Initial studies demonstrated reduction in esophageal mural distensibility that was associated with an increased risk of food impaction.24Kwiatek M.A. Hirano I. Kahrilas P.J. Rothe J. Luger D. Pandolfino J.E. Mechanical properties of the esophagus in eosinophilic esophagitis.Gastroenterology. 2011; 140: 82-90Google Scholar, 25Nicodeme F. Hirano I. Chen J. Robinson K. Lin Z. Xiao Y. et al.Esophageal distensibility as a measure of disease severity in patients with eosinophilic esophagitis.Clin Gastroenterol Hepatol. 2013; 11: 1101-1107.e1Google Scholar Preliminary studies using functional lumen imaging probe have demonstrated a significant improvement in esophageal distensibility after the administration of topical corticosteroids and anti–IL-4 receptor antibody therapy.21Hirano I. Dellon E.S. Hamilton J.D. Collins M.H. Peterson K.A. Chehade M. et al.Dupilumab efficacy and safety in adult patients with active eosinophilic esophagitis: a randomized double-blind placebo-controlled phase 2 trial. Presented at: American College of Gastroenterology National Meeting. October, Orlando (FL)2017Google Scholar, 26Carlson D.A. Hirano I. Zalewski A. Gonsalves N. Lin Z. Pandolfino J.E. Improvement in esophageal distensibility in response to medical and diet therapy in eosinophilic esophagitis.Clin Transl Gastroenterol. 2017; 8: e119Google Scholar Although published clinical trials do not exist for sialic acid–binding Ig-like lectin 8 (Siglec-8), its exclusive expression by eosinophils and mast cells makes it an interesting therapeutic target for EGIDs. Blockade of Siglec-F, the murine homolog in experimental murine eosinophilic disease, led to a reduction of eosinophils in the esophagus. This was associated with decreased angiogenesis, deposition of fibronectin, and basal zone hyperplasia, which are key aspects of EoE pathogenesis.27Rubinstein E. Cho J.Y. Rosenthal P. Chao J. Miller M. Pham A. et al.Siglec-F inhibition reduces esophageal eosinophilia and angiogenesis in a mouse model of eosinophilic esophagitis.J Pediatr Gastroenterol Nutr. 2011; 53: 409-416Google Scholar More importantly, engagement of Siglec-8 induces eosinophil cell death and decreases mediator release by mast cells.28Radonjic-Hoesli S. Valent P. Klion A.D. Wechsler M.E. Simon H.U. Novel targeted therapies for eosinophil-associated diseases and allergy.Annu Rev Pharmacol Toxicol. 2015; 55: 633-656Google Scholar Recent abstracts presented at the 2018 AAAAI meeting demonstrated that in a mouse model of eosinophilic gastritis, a novel antibody that targets Siglec-8 (AK002) resulted in selective depletion of tissue and blood eosinophils and a reduction in mast cells.29Youngblood B.B. Brock E.C. Leung J. Bebbington C. Tomasevic N. Anti-siglec-8 antibody reduced eosinophil and mast cell infiltration in a mouse model of eosinophilic gastritis: a novel therapeutic approach for eosinophilic gastrointestinal diseases.Gastroenterology. 2018; 154: S1358Google Scholar, 30Youngblood B.B. Brock E.C. Leung J. Bebbington C. Tomasevic N. Ak002, a first-in-class, humanized, non-fucosylated IGG1 siglec-8 antibody selectively depletes blood and tissue eosinophils. June, Digestive Diseases Week Meeting, Washington, DC2018Google Scholar A clinical trial is further investigating the direct role of Siglec-8 in EGIDs. Two genomics studies initially identified TSLP single nucleotide polymorphisms in patients with EoE.31Rothenberg M.E. Spergel J.M. Sherrill J.D. Annaiah K. Martin L.J. Cianferoni A. et al.Common variants at 5q22 associate with pediatric eosinophilic esophagitis.Nat Genet. 2010; 42: 289-291Google Scholar, 32Sherrill J.D. Gao P.S. Stucke E.M. Blanchard C. Collins M.H. Putnam P.E. et al.Variants of thymic stromal lymphopoietin and its receptor associate with eosinophilic esophagitis.J Allergy Clin Immunol. 2010; 126: 160-165.e3Google Scholar More recent studies have confirmed that this risk factor TSLP expression is increased in patients with EoE as compared with controls in the differentiated suprabasal layer of the epithelium. Noti et al33Noti M. Wojno E.D. Kim B.S. Siracusa M.C. Giacomin P.R. Nair M.G. et al.Thymic stromal lymphopoietin-elicited basophil responses promote eosinophilic esophagitis.Nat Med. 2013; 19: 1005-1013Google Scholar examined TSLP function in murine experimental EoE associated with food impaction, and their data suggest that TSLP recruits basophils with downstream effects on IL-4 and ultimately eosinophils. TSLP enhances the migration of eosinophils, likely in combination with IL-33, which enhances IL-5 and IL-13 production.34Smith S.G. Gugilla A. Mukherjee M. Merim K. Irshad A. Tang W. et al.Thymic stromal lymphopoietin and IL-33 modulate migration of hematopoietic progenitor cells in patients with allergic asthma.J Allergy Clin Immunol. 2015; 135: 1594-1602Google Scholar Importantly, blockade of TSLP pathways abated the eosinophilic inflammation and food impaction in the murine model. Gauvreau et al35Gauvreau G.M. O'Byrne P.M. Boulet L.P. Wang Y. Cockcroft D. Bigler J. et al.Effects of an anti-TSLP antibody on allergen-induced asthmatic responses.N Engl J Med. 2014; 370: 2102-2110Google Scholar reported on a double-blind placebo-controlled study of tezepelumab (AMG 157), a human monoclonal IgG2 antibody against TSLP, for use in the treatment of allergic asthma. The authors observed a reduction in early and late asthmatic responses, although the potential utility for EGIDs is unclear due to limited data regarding the role of TSLP. Although integrins have not been well studied in EGIDs, they have offered a therapeutic target in inflammatory diseases such as inflammatory bowel disease and rheumatoid arthritis. Brandt et al36Brandt E.B. Zimmermann N. Muntel E.E. Yamada Y. Pope S.M. Mishra A. et al.The alpha4bbeta7-integrin is dynamically expressed on murine eosinophils and involved in eosinophil trafficking to the intestine.Clin Exp Allergy. 2006; 36: 543-553Google Scholar described the alpha4beta7 integrin on leukocytes in 1994. This integrin plays a role in eosinophil recruitment to the intestine36Brandt E.B. Zimmermann N. Muntel E.E. Yamada Y. Pope S.M. Mishra A. et al.The alpha4bbeta7-integrin is dynamically expressed on murine eosinophils and involved in eosinophil trafficking to the intestine.Clin Exp Allergy. 2006; 36: 543-553Google Scholar, 37Oyoshi M.K. Elkhal A. Scott J.E. Wurbel M.A. Hornick J.L. 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Matthaei K.I. et al.ICAM-1-dependent pathways regulate colonic eosinophilic inflammation.J Leukoc Biol. 2006; 80: 330-341Google Scholar reported that the beta2 integrin factors in colonic eosinophil recruitment, suggesting that a role in lower EGIDs may also be a consideration. Cadherin 26 was recently found to be increased in pathologic allergic inflammation including that of EoE, and data suggested that it enhances cellular adhesion to alpha4beta7 integrin and binds directly to alphaE and alpha4.41Caldwell J.M. Collins M.H. Kemme K.A. Sherrill J.D. Wen T. Rochman M. et al.Cadherin 26 is an alpha integrin-binding epithelial receptor regulated during allergic inflammation.Mucosal Immunol. 2017; 10: 1190-1201Google Scholar This modulated CD4 T-cell activation, which is critical in EGIDs, underscores potential for integrin targeting. A recent retrospective series described improved histopathology in 5 patients with EGID following therapy with vedolizumab, but exposure to corticosteroids may have affected the responses.42Kim H.P. Reed C.C. Herfarth H.H. Dellon E.S. Vedolizumab treatment may reduce steroid burden and improve histology in patients with eosinophilic gastroenteritis.Clin Gastroenterol Hepatol. 2018; ([Epub ahead of print])https://doi.org/10.1016/j.cgh.2018.03.024Google Scholar The results of further studies are nonetheless awaited. Eotaxins, produced in large part by epithelial cells, play a crucial role in the chemotaxis of eosinophils to tissue. Activated eosinophils, mast cells, and fibroblasts are also capable of producing eotaxins,43Wechsler J.B. Bryce P.J. Allergic mechanisms in eosinophilic esophagitis.Gastroenterol Clin North Am. 2014; 43: 281-296Google Scholar although the relative contribution of each cell type is unclear. Eotaxins can be modulated by mast cell proteases,44Gela A. Kasetty G. 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Huo X. Yu C. Zhang Q. Pham T.H. et al.Omeprazole blocks STAT6 binding to the eotaxin-3 promoter in eosinophilic esophagitis cells.PLoS One. 2012; 7: e50037Google Scholar, 50Park J.Y. Zhang X. Nguyen N. Souza R.F. Spechler S.J. Cheng E. Proton pump inhibitors decrease eotaxin-3 expression in the proximal esophagus of children with esophageal eosinophilia.PLoS One. 2014; 9: e101391Google Scholar TGF-β1 has long been known to hold a critical profibrotic role in the pathogenesis of EoE. Muir et al51Muir A.B. Dods K. Henry S.J. Benitez A.J. Lee D. Whelan K.A. et al.Eosinophilic esophagitis-associated chemical and mechanical microenvironment shapes esophageal fibroblast behavior.J Pediatr Gastroenterol Nutr. 2016; 63: 200-209Google Scholar examined fibroblasts that were treated with TGF-β1 and observed increased markers of fibrosis. Notably, the stiffness of the matrix affected the response to TGF-β1, suggesting that increased rigidity with disease chronicity may exacerbate fibrosis development. Aceves et al52Aceves S.S. Chen D. Newbury R.O. Dohil R. Bastian J.F. Broide D.H. Mast cells infiltrate the esophageal smooth muscle in patients with eosinophilic esophagitis, express TGF-beta1, and increase esophageal smooth muscle contraction.J Allergy Clin Immunol. 2010; 126: 1198-1204.e4Google Scholar identified TGF-β1+ mast cells in the smooth muscle layer. Notably here, TGF-β1 enhanced smooth muscle contraction, likely via phospholamban,53Beppu L.Y. Anilkumar A.A. Newbury R.O. Dohil R. Broide D.H. Aceves S.S. TGF-beta1-induced phospholamban expression alters esophageal smooth muscle cell contraction in patients with eosinophilic esophagitis.J Allergy Clin Immunol. 2014; 134: 1100-1107.e4Google Scholar which supported a contribution to disease symptoms. Blockade of TGF- β 1 signaling in human esophageal fibroblasts and muscle cells led to reduced fibronectin and collagen.54Rieder F. Nonevski I. Ma J. Ouyang Z. West G. Protheroe C. et al.T-helper 2 cytokines, transforming growth factor beta1, and eosinophil products induce fibrogenesis and alter muscle motility in patients with eosinophilic esophagitis.Gastroenterology. 2014; 146 (e1-9): 1266-1277Google Scholar TGF-β 1 is also active in the epithelial layer of the esophagus. Nguyen et al55Nguyen N. Fernando S.D. Biette K.A. Hammer J.A. Capocelli K.E. Kitzenberg D.A. et al.TGF-beta1 alters esophageal epithelial barrier function by attenuation of claudin-7 in eosinophilic esophagitis.Mucosal Immunol. 2018; 11: 415-426Google Scholar recently reported that TGF-β1 alters epithelial barrier function via claudin-7, and Rawson et al56Rawson R. Yang T. Newbury R.O. Aquino M. Doshi A. Bell B. et al.TGF-beta1-induced PAI-1 contributes to a profibrotic network in patients with eosinophilic esophagitis.J Allergy Clin Immunol. 2016; 138: 791-800.e4Google Scholar found a role in plasminogen activator inhibitor-1 (PAI-1) signaling. Together, the data suggest that TGF-β1 may prove a useful target in patients with persistent symptoms that are associated with fibrotic disease. A multicenter, proof-of-concept study is currently investigating the effectiveness of losartan, an antihypertensive agent that has been demonstrated to inhibit the effects of TGF-β in experimental models.57Wengrower D. Zanninelli G. Latella G. Necozione S. Metanes I. Israeli E. et al.Losartan reduces t