Potential role of thioredoxin-interacting protein in non-IgE mast cell degranulation

Abstract

Abstract Non-IgE mediated pathways of mast cell degranulation result in similar pathological outcomes as IgE mediated degranulation without prior IgE sensitization thereby making it difficult to identify causative agents and develop therapeutics for patients. We have demonstrated that 20 nm silver nanoparticles (AgNP) induce non-IgE mast cell degranulation through an unknown mechanism. However, we have established that this non-IgE response is strain dependent with C57BL/6 bone marrow derived mast cells (BMMCs) being high responders and LP/J BMMCs being low responders. Further, RNA sequencing of high-responder and low-responder BMMCs demonstrated a significant increase in thioredoxin-interacting protein (txnip) in the low-responders after AgNP mediated degranulation. We explored this protein to determine its regulatory potential in non-IgE mast cell degranulation. At 1hr following exposure to AgNP, txnip mRNA levels increased in LP/J but not C57BL/6 which confirmed RNAseq results. Txnip protein levels were similarly decreased in BMMCs from both strains at 1hr; however, there was an increase in the low-responder BMMCs at six hours post-exposure that did not occur in the high-responder BMMCs. siRNA knockdown of txnip resulted in increased BMMC degranulation by AgNP. Txnip is strongly involved in cellular metabolism. Seahorse XfP results demonstrated a lower energy and glycolytically focused phenotype in low-responders compared to high-responders. C57BL/6 have significantly lowered glycolytic capacity after AgNP-mediated degranulation not present in LP/J. Our data suggests that txnip plays a role in non-IgE mediated mast cell degranulation and may modulate cellular metabolism.