Regulation of Interleukin-1β and Tumor Necrosis Factor Secretion from Human Mast Cell
cells are haematopoietically-derived tissue immune cells that participate in allergy,
immunity and inflammation through secretion of numerous pro-inflammatory mediators. The
peptide substance P (SP) and the cytokines interleukin (IL)-1β and tumor necrosis
factor (TNF) have been implicated in inflammatory processes. Here we report that IL-33,
a member of the IL-1 family of cytok... read moreines, together with SP markedly increase IL-1β
and TNF gene expression in cultured human LAD2 and primary mast cells derived from
umbilical cord blood. SP and IL-33 in combination also greatly stimulate IL-1β and
TNF secretion. Two different Neurokinin-1 (NK-1) receptor antagonists and a ST2
receptor-neutralizing antibody inhibit IL-1β and TNF secretion stimulated by SP
and IL-33. Additionally, NK-1 siRNA and ST2 siRNA decrease TNF secretion when stimulated
by SP and IL-33 in cultured human mast cells. Surprisingly, NK-1 antagonists also
inhibit IL-1β and TNF secretion when stimulated only by IL-33; ST2 receptor
reduction also decreases SP-stimulated TNF secretion, suggesting an interaction between
NK-1 and ST2 receptors. Additionally, IL-33 increases the expression of NK-1 gene and
surface protein expression, as well as phosphorylation of IKβ-α.
Methoxyluteolin inhibits IL-1β and TNF gene expression and secretion, as well as
phosphorylation of p-IΚB-α stimulated by SP and IL-33. These findings
identify a unique amplification process of IL-1β and TNF synthesis and secretion
via interaction of NK-1 and ST2 receptors inhibitable by methoxyluteolin. We also
investigated the secretion of IL-1β from cultured human mast cells and its
regulation by the NLRP3 inflammasome, which is crucial in inflammatory diseases. We
found that in addition to increasing IL-1β synthesis, SP and IL-33 also increase
caspase-1 gene expression and pro-IL-1β protein expression, as well as caspase-1
activity in the supernatant fluids. Interestingly, active caspase-1 is present in
unstimulated cultured human mast cells and is secreted after stimulation, suggesting an
alternative regulation of NLRP3 inflammasome. Inflammatory responses are often
characterized by elevated levels of cytokines, but the complex interplay among peptides
and cytokines is not often considered. Here we report that the cytokine IL-33
administered in combination with the pro-inflammatory peptide SP causes a marked
increase of IL-1β and TNF synthesis and secretion from cultured human mast cells.
These responses are mediated via the activation of the SP receptor, NK-1, and the IL-33
receptor, ST2, and can be inhibited by the natural flavonoid methoxyluteolin. Our
findings reveal novel interactions that increase the understanding of inflammation and
offer new directions for the development of anti-inflammatory
Thesis (Ph.D.)--Tufts University, 2017.
Submitted to the Dept. of Pharmacology & Experimental Therapeutics.
Advisor: Theoharis Theoharides.
Committee: Martin Beinborn, Alexei Degterev, John Castellot, and Mariana Castells.
Keyword: Pharmacology.read less