Editing Mast cell (section)

===MRGPRX2 mast cell receptor===

Human mast-cell-specific G-protein-coupled receptor [[MRGPRX2]] plays a key role in the recognition of pathogen associated molecular patterns (PAMPs) and initiating an antibacterial response. MRGPRX2 is able to bind to [[competence stimulating peptide]] (CSP) 1 - a quorum sensing molecule (QSM) produced by Gram-positive bacteria.<ref>{{cite journal |last1=Pundir |first1=Priyanka |last2=Liu |first2=Rui |last3=Vasavda |first3=Chirag |last4=Serhan |first4=Nadine |last5=Limjunyawong |first5=Nathachit |last6=Yee |first6=Rebecca |last7=Zhan |first7=Yingzhuan |last8=Dong |first8=Xintong |last9=Wu |first9=Xueqing |last10=Zhang |first10=Ying |last11=Snyder |first11=Solomon H |last12=Gaudenzio |first12=Nicolas |last13=Vidal |first13=Jorge E |last14=Dong |first14=Xinzhong |title=A Connective Tissue Mast-Cell-Specific ReceptorDetects Bacterial Quorum-Sensing Moleculesand Mediates Antibacterial Immunity |journal=Cell Host & Microbe |date=July 2019 |volume=26 |issue=1 |pages=114–122 |doi=10.1016/j.chom.2019.06.003 |pmid=31278040 |url=https://www.cell.com/cell-host-microbe/pdfExtended/S1931-3128(19)30292-6 |access-date=7 July 2021|pmc=6649664 }}</ref> This leads to signal transduction to a G protein and activation of the mast cell. Mast cell activation induces the release of antibacterial mediators including ROS, TNF-α and PRGD2 which institute the recruitment of other immune cells to inhibit bacterial growth and [[biofilm]] formation.

The [[MRGPRX2]] receptor is a possible therapeutic target and can be pharmacologically activated using the agonist [[compound 48/80]] to control bacterial infection.<ref>{{cite journal |first1=Kazuhiko|last1=Tatemoto|first2=Yuko|last2=Nozaki|first3=Ryoko|last3=Tsuda|first4=Shinobu|last4=Konno|first5=Keiko|last5=Tomura|first6=Masahiro|last6=Furuno|first7=Hiroyuki|last7=Ogasawara|first8=Koji|last8=Edamura|first9=Hideo|last9=Takagi|first10=Hiroyuki|last10=Iwamura|first11=Masato|last11=Noguchi|first12=Takayuki|last12=Naito|title=Immunoglobulin E-independent activation of mast cell is mediated by Mrg receptors|journal=Biochemical and Biophysical Research Communications|volume=349|issue=4|date=2006|pages=1322–1328|doi=10.1016/j.bbrc.2006.08.177|pmid=16979137|url=https://www.sciencedirect.com/science/article/pii/S0006291X06019966|access-date=7 July 2021|url-access=subscription}}</ref> It is also hypothesised that other QSMs and even Gram-negative bacterial signals can activate this receptor. This might particularly be the case during [[Bartonella]] chronic infections where it appears clearly in human symptomatology that these patients all have a [[mast cell activation syndrome]] due to the presence of a not yet defined quorum sensing molecule (basal histamine itself?). Those patients are prone to food intolerance driven by another less specific path than the IgE receptor path: certainly the MRGPRX2 route. These patients also show cyclical skin pathergy and dermographism, every time the bacteria exits its hidden intracellular location.