Half of asthma patients present elevated type 2 inflammation driven by type 2 cytokine release in the lungs. Th2 lymphocytes are major type 2 cytokine producers and key drivers of asthma pathogenesis. Current therapies for Th2-driven diseases primarily target the activity of type 2 cytokines 1, but these strategies could be improved by combining them with approaches that block Th2 lymphocyte recruitment to inflamed tissues 2. In addition, half of the most severe asthma patients do not respond to current biologics. Augmenting the portfolio of therapeutics for allergic diseases is, therefore, crucial to improve clinical treatments. We previously identified ASB2α as a Th2 lineage-specific E3 ubiquitin ligase essential for Th2 lymphocyte function 3, 4. ASB2α triggers the polyubiquitination and proteasomal degradation of filamins A and B (FLNa/b), promoting efficient Th2 lymphocyte migration. Indeed, low levels of FLNa and FLNb driven by ASB2α in Th2 lymphocytes favor αVβ3 integrin-dependent cell migration to optimize their effector functions 4. Conversely, ASB2α deficiency reduces Th2 lymphocyte recruitment in inflamed lungs and attenuates airway inflammation in experimental asthma models. Here, we asked whether increasing FLNa/b levels pharmacologically in Th2 lymphocytes may represent a therapeutic opportunity to attenuate type 2 inflammation. We screened a compound library to identify small molecules that increase FLNa/b levels in ASB2α-expressing cells. As validation, ASB2α-expressing cells treated with the PS-341 proteasome inhibitor showed higher FLNa levels compared to untreated cells that are comparable to those measured with the ASB2αLA ubiquitin ligase defective mutant (Figure S1A). Among 16 compounds that increased FLNa-GFP levels in ASB2α-expressing cells, 12 also raised FLNb-GFP levels (Figure S1B–D). Two of them, thiostrepton (TST) and oxibendazole (OBZ), enhanced endogenous FLNa and FLNb levels in mouse Th2 lymphocytes, without affecting their viability, proliferation, or identity (Figure 1A and Figure S2A–D). We therefore postulated that TST and OBZ could be used to make the proof-of-principle that targeting the ASB2α-FLNa/b axis to attenuate type 2 inflammation is of therapeutic value. Because ASB2α-driven degradation of FLNa/b confers specific ⍺Vβ3 integrin-dependent migratory properties to Th2 lymphocytes, we studied the dynamics of TST- or OBZ-treated Th2 lymphocytes at the single-cell level. Despite similar cell surface expression of αV and β3 integrin subunits in Th2 lymphocytes treated with DMSO, TST, or OBZ (Figure S2E), TST- or OBZ-treated Th2 lymphocytes were less motile, exhibited shorter track displacement length, smaller scanned areas, lower velocity, and a rounder morphology (Videos S1–S3 and Figure 1B–H), as observed in ASB2α-deficient cells 4. Using a passive airway inflammation model, we then evaluated whether TST and OBZ inhibit type 2 immune responses in mice. C57Bl/6J recipients injected with TST- or OBZ-treated OVA-specific Th2 lymphocytes before OVA inhalations showed reduced airway inflammation, characterized by decreased cell infiltration, mucus secretion and remodeling of the airways, diminished recruitment of eosinophils in the lungs, and reduced percentages of eosinophils in the bronchoalveolar lavage fluids (BALF) and of the numbers or frequencies of Vβ5+Vα2+CD4+CD45+ cells in the lungs, BALF, and lung draining lymph nodes (LDLN) (Figure 2A–F and Figure S3A,B,D,E). Reduced IL-4, IL-5, and IL-13 secretion by LDLN cells of these mice after OVA-antigen restimulation was also measured (Figure S3C and Figure S3F). Furthermore, mice that received TST- or OBZ-treated OVA-specific Th2 lymphocytes and subsequently challenged with OVA exhibited attenuated airway hyperreactivity (AHR) to methacholine as evidenced by decreased resistance and elastance (Figure 2G). Similar decreases in AHR to methacholine were measured in mice that received ASB2cKO OT2 Th2 lymphocytes (Figure 2H). These results collectively indicate that increasing levels of FLNa and FLNb in Th2 lymphocytes is sufficient to attenuate AHR to methacholine. Because of their pleiotropic effects 5, 6, TST and OBZ are unlikely to be candidate drugs for asthma treatment. Nevertheless, our findings herein together with our previous results 4 establish the proof-of-concept that increasing the levels of FLNa/b in Th2 lymphocytes with small molecules or with ASB2α loss of function, i.e., in prophylactic settings, attenuates type 2 immune responses in mouse models of airway inflammation. Future investigations dedicated to the identification of more selective compounds and to the exploration of any potential off-target effect would be necessary for therapeutic purposes. Because FLNa and FLNb are ubiquitously expressed, increasing FLNa/b levels in Th2 lymphocytes using an ASB2α inhibitor is likely to be more relevant than a FLNa/b stabilizer. Overall, we propose that targeting the ASB2α-FLNa/b axis might be considered a potential therapeutic opportunity in Th2-driven diseases. P.G.L., and I.L. devised, performed, analyzed, and interpreted experiments and wrote the paper. L.C., K.M., and C.H. performed, analyzed, and interpreted experiments. A.S., S.D.-G., and L.L.R., contributed important ideas. Funding was acquired by P.G.L., and I.L. All authors provided critical input into the manuscript. We acknowledge the flow cytometry core facility and the Toulouse Réseau Imagerie of Infinity, Toulouse. We acknowledge the CREFRE experimental zootechny and non-Invasive exploration teams—US006/CREFRE Inserm/UT/ENVT Anexplo platform, Toulouse, for animal housing and technical assistance. We thank the Experimental Histopathology Facility of the Inserm/UT US006/CREFRE Anexplo, Toulouse, for technical assistance. This work was supported by the Institut National de la Santé et de la Recherche Médicale, the Centre National de la Recherche Scientifique and the University of Toulouse. This work was also supported by grants from Inserm Transfert (CoPoC) and Sanofi (to P.G.L. and I.L.), from Sanofi Innovation Awards Europe and the Fondation du Souffle (to P.G.L.), and from the Société Française d'Allergologie (to I.L.). P.G.L. was laureate 2023 of the Fondation du Souffle—Promotion Marina Pretolani. K. Maire was supported by a fellowship of the French Ministry of Higher Education and Research. This work was supported by Inserm Transfert. Université de Toulouse. Centre National de la Recherche Scientifique. Institut National de la Santé et de la Recherche Médicale. Société Française d'Allergologie. Fondation du Souffle. Sanofi. A.S. and S.D.-G. are employees of Sanofi. L.L.R. is an employee of NEOVACS and has received grants and/or consulting fees from NEOVACS, CSL Behring, Novartis, CEVA, and Argenx (outside of this work). The remaining authors declare no competing interests. The data that support the findings of this study are available from the corresponding authors upon reasonable request. Data S1: Supporting Information. Video S1: Time-lapse video of DMSO-treated ctrl Th2 lymphocytes seeded onto vitronectin-coated slides. Video S2: Time-lapse video of TST-treated ctrl Th2 lymphocytes seeded onto vitronectin-coated slides. Video S3: Time-lapse video of OBZ-treated ctrl Th2 lymphocytes seeded onto vitronectin-coated slides. 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Chamy et al. (Tue,) studied this question.