Proprotein convertases generate a highly functional heterodimeric form of thymic stromal lymphopoietin in humans

• Published in: Journal of allergy and clinical immunology Vol. 139; no. 5; pp. 1559 - 1567.e8
• Main Authors: Poposki, Julie A., MS, Klingler, Aiko I., PhD, Stevens, Whitney W., MD, PhD, Peters, Anju T., MD, Hulse, Kathryn E., PhD, Grammer, Leslie C., MD, Schleimer, Robert P., PhD, Welch, Kevin C., MD, Smith, Stephanie S., MD, Sidle, Douglas M., MD, Conley, David B., MD, Tan, Bruce K., MD, Kern, Robert C., MD, Kato, Atsushi, PhD
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.05.2017; Elsevier Limited
• Subjects: Allergies; Allergy and Immunology; Amino acid sequence; Asthma; Carboxypeptidase; Cells, Cultured; Chemokines; chronic rhinosinusitis; Cytokines; Cytokines - pharmacology; Dendritic cells; Disease; Disulfide bonds; Enzymes; group 2 innate lymphoid cells; Humans; Inflammation; Inflammatory diseases; Ionization; Leukocytes, Mononuclear - drug effects; Leukocytes, Mononuclear - immunology; Ligands; Lymphoid cells; Lysine carboxypeptidase; Mass spectrometry; Mass spectroscopy; Molecular weight; nasal polyps; Nasal Polyps - immunology; Otolaryngology; Peripheral blood mononuclear cells; Polyps; posttranslational modification; Proprotein Convertase 1 - pharmacology; Proprotein convertases; Protein Processing, Post-Translational; Proteins; Recombinant Proteins - pharmacology; Residues; Rhinitis; Rhinosinusitis; Scientific imaging; Sinusitis; Thymic stromal lymphopoietin; Thymus; Decanoyl-Arg-Val-Lys-Arg-chloromethylketone; CPN; NP; Nasal polyp; CRS; DTT; Mass-to-charge ratio; posttranslational modification; PTM; Carboxypeptidase; CRSwNP; m/ z; ILC2; dendritic cells; nasal polyps; Dithiothreitol; CMK; Carboxypeptidase N; Proprotein convertase subtilisin/kexin; TSLP; MS; proprotein convertases; CC chemokine ligand; CCL; PCSK; thymic stromal lymphopoietin; group 2 innate lymphoid cells; Chronic rhinosinusitis with nasal polyps; chronic rhinosinusitis; Mass spectrometry; m/z
• ISSN: 0091-6749; 1097-6825
• DOI: 10.1016/j.jaci.2016.08.040

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 matrix-assisted 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 Posttranslational modifications 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.