Introduction & Aim: Allergic inflammatory diseases are a constantly growing health concern in
westernized societies. Mast cells, the driving force behind many allergic diseases, modulate
various metabolic pathways to carry out their various functions following IgE-FceRI-mediated
activation. Tafazzin is a cardiolipin transacylase that works to remodel cardiolipin into its mature
form of tetralinoleoyl-cardiolipin. Mature cardiolipin is important for efficient energy production
through oxidative phosphorylation. The aim of this project is to study the effects of a reduction
in tafazzin protein content on IgE-mediated mast cell activation. Methods: Fetal liver-derived
mast cells (FLMCs) were treated with 1 μg/mL doxycycline for 5 days to initiate the tafazzin
knockdown. Western blotting was used to confirm a reduction in tafazzin protein content. Flow
cytometry was used to ensure that the FLMCs expressed both c-kit and FceRI receptors, and that
receptor expression was not impacted by the doxycycline treatment. Oxygen consumption rate
was measured using a Clark-type electrode. b-hexosaminidase release assays were utilized to
assess degranulation during the early phase of the allergic reaction. ELISA assays were used to
examine secretion of de novo synthesized inflammatory mediators, while qPCR assays were used
to examine gene transcription of these mediators. Results: The doxycycline inducible tafazzin
knockdown resulted in a 99.5% reduction in tafazzin protein content. This reduction was
accompanied by a 25% reduction in oxygen consumption and a 31.4% reduction in
degranulation. Secretion of CCL1, CCL2, and TNF was significantly reduced, CCL9 secretion
levels showed a decrease that approached significance. Secretion of CCL3 and IL-6 was not
impacted. Gene expression was not impacted for any of the inflammatory mediators measured.
Conclusion & Significance: These results suggest that tafazzin may play a role in mast cell
oxidative phosphorylation. Functionally, the results suggest that tafazzin plays a role in
degranulation and mediator secretion. However, since gene expression was not impacted it is
thought that the tafazzin reduction causes these decreases due to an impairment of the exocytosis
mechanism. This work adds to the growing field of immunometabolism and improves our
understanding of how mast cells modulate metabolic pathways during an allergic inflammatory
event
