Airway Epithelial State as a Treatment-Selection Router for TSLP Blockade in Severe Asthma
Year: 2026
Type: preprint
Abstract: Airway Epithelial State as a Treatment-Selection Router for TSLP Blockade in Severe Asthma Bouchelit Mohammed El Amin Founder, SCIENTIFIC INTELLIGENCE DECISIONFrankfurt, Germanywww.histamos.com | [email protected] Abstract Severe asthma is increasingly treated with biologics targeting different levels of the inflammatory network. Current treatment selection relies largely on blood eosinophils, fractional exhaled nitric oxide (FeNO), allergic phenotype, exacerbation history, and comorbidities. These markers may incompletely represent the local epithelial state in which airway alarmins are generated. This article proposes that a measurable pre-treatment airway epithelial state, defined by inducible epithelial alarmin activity and downstream inflammatory competence rather than by TSLP concentration alone, modifies the relative benefit of upstream TSLP blockade. The central prediction is that patients with a high, activatable TSLP-linked epithelial state will derive greater relative benefit from TSLP blockade than would be predicted from conventional biomarkers alone. A prospective treatment-by-state interaction study could distinguish this predictive model from a purely prognostic inflammation model and from downstream-dominant disease. Introduction Asthma is biologically heterogeneous. Biologics targeting IgE, IL-5/IL-5R, IL-4Ralpha, and TSLP act at different levels of the inflammatory network. TSLP is produced at epithelial barrier surfaces and can influence dendritic cells, innate lymphoid cells, T cells, eosinophilic inflammation, and other downstream pathways. Tezepelumab has demonstrated clinical benefit across a broad range of baseline T2 biomarker values, indicating that conventional systemic biomarkers do not fully capture upstream pathway dependency. Mechanistic studies have shown that TSLP blockade can alter bronchial epithelial inflammatory responses, including IL-33 and type-2-associated signalling. Recent transcriptomic work also suggests heterogeneity in epithelial responses according to baseline inflammatory state. These observations support a narrower and more testable proposition: the relevant treatment selector may be a local airway epithelial state rather than a single circulating biomarker. Core Hypothesis In severe uncontrolled asthma, the therapeutic importance of TSLP is conditional on the biological state of the airway epithelium. A subset of patients has an active or highly inducible epithelial state characterized by coordinated epithelial alarm signalling and a downstream immune network that is functionally responsive to TSLP-linked activation. The proposed causal sequence is: epithelial injury or environmental stimulation -> inducible epithelial alarm state -> local TSLP-linked signalling -> activation and amplification of the airway inflammatory network -> airway hyperresponsiveness and exacerbation susceptibility. In this state, blocking TSLP interrupts an upstream dependency and should therefore provide disproportionately large benefit. Conversely, another patient may have similar blood eosinophils or asthma severity but a weak TSLP-dependent epithelial state. In such a patient, downstream IL-5 or IL-4/IL-13 signalling, structural disease, or another pathway may dominate, reducing the relative advantage of upstream TSLP blockade. The central claim is therefore that treatment response should be modelled as a treatment-by-airway-state interaction, not as biomarker abundance alone. Defining the Airway State The proposed state should not be reduced to baseline TSLP concentration. It should be represented by a compact functional signature that may include inducible epithelial TSLP activity, IL-33 and related alarmin responses, stimulus-induced inflammatory output, local type-2 pathway activation, epithelial NF-kappaB-associated activity, and selected downstream cytokine responses. The purpose of this signature is not to classify severity, but to estimate whether the airway inflammatory network is functionally dependent on an upstream epithelial TSLP-linked program. Predictions · A high baseline epithelial-state score will be associated with greater relative benefit from TSLP blockade. · The epithelial state will add predictive information beyond blood eosinophils and FeNO. · Patients with similar conventional biomarkers but different epithelial states will show different treatment responses. · Some patients with low blood eosinophils may nevertheless have a high epithelial TSLP-linked state and respond strongly to TSLP blockade. · Early suppression of the epithelial inflammatory program should precede, or lie mechanistically upstream of, later improvement in exacerbation burden or airway function. · The strongest evidence will be a reproducible treatment-by-state interaction rather than a general association between the state and poor outcomes. Competing Models Conventional Biomarker Model Blood eosinophils, FeNO, allergic phenotype, exacerbation history, and clinical features are sufficient for treatment selection, and airway epithelial measurements add little incremental value. Prognostic Inflammation Model A high epithelial inflammatory state simply identifies more active disease and predicts worse outcome regardless of therapy. It does not specifically predict benefit from TSLP blockade. Downstream-Dominant Model Even when epithelial TSLP activity is present, clinically relevant dependency resides mainly in IL-5-, IL-4/IL-13-, eosinophil-, or other downstream pathways. The epithelial state therefore does not determine the preferred biologic. Decisive Experimental Design The decisive study should measure the epithelial state before therapy and test whether it modifies treatment effect. Patients with severe uncontrolled asthma would undergo baseline airway sampling using a clinically feasible compartment, ideally with a bronchial subset for mechanistic validation. Baseline measurements may include a targeted epithelial transcriptomic or expression profile, inducible TSLP-linked activity, IL-33, selected type-2 cytokines, NF-kappaB-associated response, blood eosinophils, FeNO, exacerbation history, corticosteroid exposure, and relevant clinical covariates. Patients would then receive upstream TSLP blockade or an appropriate downstream biologic strategy. The primary analysis would test the baseline epithelial-state x treatment interaction for annualized exacerbation rate, time to first exacerbation, asthma-control improvement, lung-function change, and clinically meaningful response or remission. Predictive Versus Prognostic Criterion This distinction is essential. If patients with a high epithelial state have worse outcomes regardless of treatment, the signature is prognostic. If high-state patients obtain a specifically greater treatment effect from TSLP blockade relative to the comparator, the signature becomes predictive and supports the airway-state-router model. Falsification Criteria · The baseline epithelial state does not interact reproducibly with TSLP-blockade treatment effect. · The apparent signal disappears after adjustment for eosinophils, FeNO, exacerbation history, corticosteroid exposure, or relevant confounders. · The state predicts disease severity similarly across treatments rather than preferential response to TSLP blockade. · Conventional biomarkers perform equally well or better without epithelial-state information. · Local epithelial-state changes occur after treatment but are unrelated to clinical response. · An independent cohort fails to reproduce the treatment-by-state interaction. Strongest Success Criterion The strongest evidence would be: baseline epithelial state measured before treatment -> reproducible treatment-by-state interaction -> incremental predictive value beyond eosinophils and FeNO -> early suppression of the predicted epithelial pathway after TSLP blockade -> subsequent clinical benefit -> replication in an independent cohort. Discussion The proposed framework does not claim that TSLP is newly discovered as an upstream mediator of asthma. Its narrower claim is that a prospectively measured airway epithelial state may function as a treatment-selection variable. Existing studies show that tezepelumab can alter epithelial inflammatory responses and that baseline inflammatory state may influence molecular response. However, those observations do not yet establish that a baseline epithelial state predicts the relative clinical benefit of TSLP blockade compared with downstream biologic treatment. The proposed treatment-by-state experiment directly tests this unresolved question. A positive result could support a move from phenotype-based biologic selection toward functional airway-state selection. A negative result would indicate that epithelial-state measurements add mechanistic understanding without sufficient treatment-selection value. Conclusion The therapeutic relevance of TSLP may depend less on the presence of asthma or on a single systemic biomarker than on whether an active TSLP-linked epithelial program is functionally driving the airway inflammatory network. The central testable proposition is that a prospectively measured airway epithelial state predicts the relative benefit of upstream TSLP blockade beyond established systemic biomarkers. Selected References 1. Corren J, et al. Baseline type 2 biomarker levels and response to tezepelumab in severe asthma. Allergy. 2022;77:1786-1796. doi:10.1111/all.15197. 2. Sverrild A, et al. Tezepelumab decreases airway epithelial IL-33 and T2-inflammation in response to viral stimulation in patients with asthma. Allergy. 2024;79:656-666. doi:10.1111/all.15918. 3. Ramu S, et al. Tezepelumab alters airway epithelial transcriptional responses and epithelial-smooth muscle signalling in uncontrolled asthma. Frontiers in Immunology. 2026;17. doi:10.338
Author: Bouchelit, Mohammed El Amin
Language: English
Subfield: Physiology (medical)
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W7225264220
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