SP and IL-33 together markedly enhance TNF synthesis and secretion from human mast cells mediated by the interaction of their receptors

Abstract

The peptide substance P (SP) and the cytokine tumor necrosis factor (TNF) have been implicated in inflammatory processes. Mast cells are recognized as important in inflammatory responses. Here, we report that IL-33 (30 ng/mL), a member of the IL-1 family of cytokines, administered in combination with SP (1 μM), markedly increase (by 1,000-fold) TNF gene expression in cultured human LAD2 and primary mast cells derived from umbilical cord blood. SP (0.01-1 μM) and IL-33 (1-100 ng/mL) in combination also greatly stimulate TNF secretion (by 4,500-fold). Pretreatment of LAD2 cells with two different neurokinin-1 (NK-1) receptor antagonists and siRNA inhibits TNF secretion by 50% (P < 0.001) when stimulated by SP and IL-33. Pretreatment of LAD2 cells with a neutralizing antibody for IL-33 receptor, ST2, inhibits TNF secretion by 50% (P < 0.001), and ST2 siRNA decreases TNF secretion by 30% (P < 0.05), when stimulated by SP and IL-33. Surprisingly, NK-1 antagonists also inhibit 50% of TNF secretion (P < 0.001) when stimulated only by IL-33, and ST2 receptor reduction also decreases SP-stimulated TNF secretion by 30% (P < 0.05), suggesting an interaction between NK-1 and ST2 receptors. Moreover, IL-33 increases NK-1 gene and surface protein expression, as well as IKβ-α phosphorylation. Pretreatment of LAD2 cells with 5,7,3′,4′-tetramethoxyflavone (methoxyluteolin) (1-100 μM) inhibits (P < 0.001) TNF gene expression (98%) and secretion (64%) at 50 μM and phosphorylation of p-IKB-α at 1 μM when stimulated by SP and IL-33. These findings identify a unique amplification process of TNF synthesis and secretion via the interaction of NK-1 and ST2 receptors inhibitable by methoxyluteolin. mast cells | substance P | interleukin-33 | tumor necrosis factor | inflammation

Human mast cells and basophils—How are they similar how are they different?

“…IL‐33 per se does not induce degranulation, but enhances production of CXCL8/IL‐8 and IL‐13 from anti‐IgE‐stimulated human mast cells . IL‐33 enhances substance P‐induced TNF‐α and Vascular Endothelial Growth Factor (VEGF) release from human mast cells . IL‐33 also enhances CXCL8/IL‐8, histamine, and IL‐10 release from immune complex‐triggered human mast cells .…”

Non‐IgE mediated mast cell activation

“…In addition, in the presence of SCF, IL‐33 can also induce TNF production in MCs via a MK2/3‐, ERK1/2‐, and PI3K‐dependent pathway . Recently, Taracanova et al have shown that IL‐33 and SP together amplify TNF secretion from MCs, which is mediated by the interaction of NK‐1R and ST2 receptors . In addition, IL‐33 and FcɛRI act synergistically in the production of TNFα by MCs .…”

The role and relevance of mast cells in urticaria

“…Human skin mast cells express the G‐protein coupled receptor (GPCR) mas‐related gene X2 (MrgX2) that allows them to be activated for degranulation by polybasic substances, such as compound 48/80 and poly‐L‐lysine . Mast cells also express neuropeptide receptors, such as neurokinin 1 and 2 receptors (NK1R and NK2R), calcitonin gene‐related peptide receptor (CGRPR), and the neurotrophin receptors, tropomyosin‐related kinase A (TrkA), TrkB, and TrkC . Neuropeptides such as substance P, vasoactive intestinal peptide (VIP), and somatostatin, but not eledoisin, physalaemin, neurokinin A, neurokinin B, calcitonin gene‐related peptide (CGRP) stimulate both mast cell degranulation and cytokine production .…”