IL-1α promotes a cascade of cytokine production from epithelial cells culminating in Th2 immunity to house dust mite allergens.

Sp3 is a ubiquitous transcription factor closely related to Sp1. Here we show that Sp3 is a target for SUMO modi®cation in vivo and in vitro. SUMO modi®cation of Sp3 occurs at a single lysine located between the second glutamine-rich activation domain and the DNA-binding domain. Mutational analyses identi®ed the sequence IKXE as essential for SUMO conjugation to Sp3. We identi®ed the protein inhibitor of activated STAT1 (PIAS1) as an interaction partner of Sp3 and Ubc9. Moreover, PIAS1 strongly stimulated SUMO conjugation to Sp3, thus acting as an E3 ligase for SUMO conjugation to Sp3. All mutations that prevented SUMO modi®cation in vitro strongly enhanced the transcriptional activity of Sp3, showing that SUMO modi®cation silences Sp3 activity. SUMOmodi®ed Sp3 bound to DNA with similar speci®city and af®nity as unmodi®ed Sp3. However, DNA-bound Sp3 did not act as a substrate for SUMO modi®cation.

Asthma is a T helper 2 (Th2)-cell-mediated disease; however, recent findings implicate Th17 and innate lymphoid cells also in regulating airway inflammation. Herein, we have demonstrated profound interleukin-21 (IL-21) production after house dust mite (HDM)-driven asthma by using T cell receptor (TCR) transgenic mice reactive to Dermatophagoides pteronyssinus 1 and an IL-21GFP reporter mouse. IL-21-producing cells in the mediastinal lymph node (mLN) bore characteristics of T follicular helper (Tfh) cells, whereas IL-21(+) cells in the lung did not express CXCR5 (a chemokine receptor expressed by Tfh cells) and were distinct from effector Th2 or Th17 cells. Il21r(-/-) mice developed reduced type 2 responses and the IL-21 receptor (IL-21R) enhanced Th2 cell function in a cell-intrinsic manner. Finally, administration of recombinant IL-21 and IL-25 synergistically promoted airway eosinophilia primarily via effects on CD4(+) lymphocytes. This highlights an important Th2-cell-amplifying function of IL-21-producing CD4(+) T cells in allergic airway inflammation.

Sp3 is a ubiquitous transcription factor closely related to Sp1. Previous analyses showed that, unlike Sp1, Sp3 fails to activate transcription in certain promoter settings. This is due to the presence of an inhibitory domain located between the second glutamine-rich activation domain and the DNA-binding domain. To further analyze the transcriptional properties of Sp3, we have expressed and purified recombinant Sp3 and Sp1 as epitope-tagged proteins from stable transfected insect cells. We found that Sp3 does act as a strong activator similar to Sp1 in an in vitro transcription assay using Sp1/Sp3-depleted HeLa nuclear extract. However, on the same promoter Sp3 is almost inactive when transfected into cells. Mutational studies demonstrate that a single lysine residue is responsible for the low transcriptional activity of Sp3 in vivo. We show that Sp3, but not a mutant of Sp3 that lacks this lysine residue, is highly acetylated in vivo. Our results strongly suggest that the transcriptional activity of Sp3 is regulated by acetylation. The consequences of acetylation for the activity of Sp3 are discussed.

The S aureus-derived protein SplD is a potent allergen of S aureus and induces a T2-biased inflammatory response in the airways in an IL-33-dependent but TRL4-independent manner. The soluble ST2 receptor could be an efficient strategy to interfere with SplD-induced T2 inflammation but does not prevent the allergic sensitization.

The pro-inflammatory cytokine thymic stromal lymphopoietin (TSLP) is pivotal to the pathophysiology of widespread allergic diseases mediated by type 2 helper T cell (Th2) responses, including asthma and atopic dermatitis. The emergence of human TSLP as a clinical target against asthma calls for maximally harnessing its therapeutic potential via structural and mechanistic considerations. Here we employ an integrative experimental approach focusing on productive and antagonized TSLP complexes and free cytokine. We reveal how cognate receptor TSLPR allosterically activates TSLP to potentiate the recruitment of the shared interleukin 7 receptor α-chain (IL-7Rα) by leveraging the flexibility, conformational heterogeneity and electrostatics of the cytokine. We further show that the monoclonal antibody Tezepelumab partly exploits these principles to neutralize TSLP activity. Finally, we introduce a fusion protein comprising a tandem of the TSLPR and IL-7Rα extracellular domains, which harnesses the mechanistic intricacies of the TSLP-driven receptor complex to manifest high antagonistic potency.

Signalling molecules and pathways that mediate crosstalk between various tumour cellular compartments in cancer metastasis remain largely unknown. We report a mechanism of the interaction between perivascular cells and tumour-associated macrophages (TAMs) in promoting metastasis through the IL-33–ST2-dependent pathway in xenograft mouse models of cancer. IL-33 is the highest upregulated gene through activation of SOX7 transcription factor in PDGF-BB-stimulated pericytes. Gain- and loss-of-function experiments validate that IL-33 promotes metastasis through recruitment of TAMs. Pharmacological inhibition of the IL-33–ST2 signalling by a soluble ST2 significantly inhibits TAMs and metastasis. Genetic deletion of host IL-33 in mice also blocks PDGF-BB-induced TAM recruitment and metastasis. These findings shed light on the role of tumour stroma in promoting metastasis and have therapeutic implications for cancer therapy.

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