Conclusion
Replacing mouse MrgprB2 with functional human MRGPRX2 in primary BMMCs and their engraftment in MC-deficient mice demonstrated the expression of this receptor in different tissues, which provides unique opportunities to study receptor signaling ex vivo and disease phenotype in vivo.
Methods
MrgprB2-/- bone marrow (BM) cells were transduced with retrovirus encoding MRGPRX2 and differentiated into BMMCs (MRGRPX2-BMMCs) ex vivo. Cell surface MRGPRX2 expression was determined by flow cytometry. Effects of substance P (SP) and LL-37 on Ca2+ mobilization, degranulation and TNF-α generation were determined. MRGPRX2-BMMCs were engrafted intraperitoneally into MC-deficient Wsh/Wsh mice. After 6-8 weeks, immunofluorescence staining was performed on peritoneal lavage cells (PLCs), and sections of small intestine and colon with anti c-Kit and anti-MRGPRX2 antibodies. SP-induced degranulation in PLCs obtained from engrafted mice was determined.
Results
MRGPRX2-BMMCs expressed cell surface MRGPRX2 and responded to both SP and LL-37 for Ca2+ mobilization, degranulation and TNF-α generation. Furthermore, Wsh/Wsh mice engrafted with MRGPRX2-BMMCs expressed the receptor in peritoneal, intestinal and colonic MCs. In addition, PLCs from engrafted mice responded to SP for degranulation.