Journal
JOURNAL OF ALLERGY AND CLINICAL IMMUNOLOGY
Volume 139, Issue 5, Pages 1559-+Publisher
MOSBY-ELSEVIER
DOI: 10.1016/j.jaci.2016.08.040
Keywords
Carboxypeptidase; chronic rhinosinusitis; dendritic cells; group 2 innate lymphoid cells; nasal polyps; posttranslational modification; proprotein convertases; thymic stromal lymphopoietin
Categories
Funding
- National Institutes of Health [R01 AI104733, R21 HL113913, U19 AI106683, R37 HL068546]
- Ernest S. Bazley Foundation
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Rationale: Thymic stromal lymphopoietin (TSLP) is known to be elevated and truncated in nasal polyps (NPs) of patients with chronic rhinosinusitis and might play a significant role in type 2 inflammation in this disease. However, neither the structure nor the role of the truncated products of TSLP has been studied. Objective: We sought to investigate the mechanisms of truncation of TSLP in NPs and the function of the truncated products. Methods: We incubated recombinant human TSLP with NP extracts, and determined the protein sequence of the truncated forms of TSLP using Edman protein sequencing and matrixassisted laser desorption/ionization-time of flight mass spectrometry. We investigated the functional activity of truncated TSLP using a PBMC-based bioassay. Results: Edman sequencing and mass spectrometry results indicated that NP extracts generated 2 major truncated products, TSLP (residues 29-124) and TSLP (131-159). Interestingly, these 2 products remained linked with disulfide bonds and presented as a dimerized form, TSLP (29-124 + 131-159). We identified that members of the proprotein convertase were rate-limiting enzymes in the truncation of TSLP between residues 130 and 131 and generated a heterodimeric unstable metabolite TSLP (29-130 + 131-159). Carboxypeptidase N immediately digested 6 amino acids from the C terminus of the longer subunit of TSLP to generate a stable dimerized form, TSLP (29-124 + 131-159), in NPs. These truncations were homeostatic but primate-specific events. A metabolite TSLP (29-130 + 131-159) strongly activated myeloid dendritic cells and group 2 innate lymphoid cells compared with mature TSLP. Conclusions: Posttranslationalmodifications control the functional activity of TSLP in humans and overproduction of TSLP may be a key trigger for the amplification of type 2 inflammation in diseases.
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