Thymic Stromal Lymphopoietin (TSLP) is the master upstream alarmin that initiates type 2 inflammatory cascades at barrier surfaces. Unlike downstream cytokines (IL-4, IL-5, IL-13), targeting TSLP intercepts the entire T2 inflammatory axis from a single upstream node — demonstrated by tezepelumab's efficacy across all asthma endotypes. MAbSilico engineers differentiated anti-TSLP antibodies and TSLP-axis bispecifics from a curated database of 210+ annotated sequences, exploring both ligand neutralization and receptor blockade strategies.
TSLP acts as the proximal initiator of the T2 inflammatory cascade — secreted by epithelial cells at barrier surfaces in direct response to environmental triggers. By targeting TSLP, antibodies intercept the entire inflammatory axis before it amplifies.
TSLP exists as two distinct isoforms generated from different promoter regions: the long-form (lfTSLP) is significantly upregulated under inflammatory conditions and serves as the primary driver of pathological T2 immune responses. The short-form (sfTSLP) is constitutively expressed at barrier surfaces and possesses potent antimicrobial and immunoregulatory properties. The C-terminal region of sfTSLP contains a 34-amino acid peptide (MKK34) with direct antimicrobial activity — making sfTSLP a critical homeostatic molecule that must not be disrupted by therapeutic antibodies.
TSLP engages a heterodimeric receptor complex composed of TSLPR and IL-7Rα. This assembly triggers JAK1/JAK2 phosphorylation and STAT5 activation. Beyond the canonical JAK-STAT pathway, TSLP also cascades through MAPK, PI3K and JNK pathways — collectively driving maturation of myeloid dendritic cells that prime naïve CD4+ T cells toward a Th2 phenotype. Crucially, TSLP potently activates ILC2s (innate lymphoid cells type 2), which produce vast quantities of IL-5 and IL-13 independent of adaptive T-cell recognition — explaining why TSLP blockade works across allergic and non-allergic asthma endotypes.
| Isoform | Expression | Function |
|---|---|---|
| lfTSLP (long-form) | Induced by inflammation, allergens, pathogens | Drives Th2 polarization, ILC2 activation, eosinophil recruitment. Primary therapeutic target. |
| sfTSLP (short-form) | Constitutive at barrier surfaces | Antimicrobial defense (MKK34 peptide), barrier homeostasis. Must be preserved by therapeutic antibodies. |
Engineering implication: The critical selectivity challenge is neutralizing lfTSLP without disrupting sfTSLP's antimicrobial function. Tezepelumab achieves this via epitope selection on lfTSLP. The choice of IgG2λ isotype (minimal ADCC) avoids destruction of TSLP-producing epithelial cells essential for barrier homeostasis.
The TSLP therapeutic landscape is bifurcated between direct ligand neutralization (the tezepelumab paradigm) and receptor antagonism (verekitug) — each with distinct pharmacodynamic implications. A third wave of multi-specific formats targets TSLP simultaneously with downstream effectors.
Tezepelumab (Tezspire), the first-in-class FDA-approved anti-TSLP, is an IgG2λ monoclonal antibody that binds circulating lfTSLP with high affinity, preventing its interaction with the TSLPR/IL-7Rα complex. The choice of IgG2λ isotype is deliberate: it minimizes ADCC and CDC effector functions, ensuring the antibody acts purely as a neutralizer without destroying TSLP-producing epithelial cells. Clinical success in severe asthma is remarkable — reducing exacerbations across all biomarker-defined endotypes.
Verekitug (UPB-101), an IgG1 mAb targeting TSLPR with KD < 1 pM, represents a strategic paradigm shift. While ligand-targeting antibodies must neutralize every molecule of TSLP produced, a receptor antagonist needs only to occupy the receptor population on target immune cells. This stoichiometric advantage translates to sustained target engagement for 24–32 weeks, suggesting quarterly or biannual dosing — a transformative durability benefit for chronic atopic disease management.
Our 6-step workflow navigates the TSLP axis engineering challenge: lfTSLP selectivity, IgG isotype choice, and multi-specific pairing for comprehensive T2 blockade.
From lfTSLP-selective ligand neutralizers to ultra-high-affinity receptor blockers and trispecific formats — MAbSilico identifies differentiated positions in the TSLP axis from 210+ annotated sequences.