Markers Involved in Innate Immunity and Neutrophil Activation are Elevated during Acute Human Anaphylaxis: Validation of a Microarray Study

Background: We have previously identified the upregulation of the innate immune response, neutrophil activation, and apoptosis during anaphylaxis using a microarray approach. This study aimed to validate the differential gene expression and investigate protein concentrations of “hub genes” and upstream regulators during anaphylaxis. Methods: Samples were collected from patients with anaphylaxis on their arrival at the emergency department, and after 1 and 3 h. mRNA levels of 11 genes ( interleukin-6 [IL-6], IL-10, oncostatin M [OSM], S100A8, S100A9, matrix metalloproteinase 9 [MMP9], FASL, toll-like receptor 4 [TLR4], MYD88, triggering receptor expressed on myeloid cells 1 [TREM1] , and cluster of differentiation 64 [CD64] ) were measured in peripheral blood leucocytes using qPCR. Serum protein concentrations were measured by ELISA or cytometric bead array for 6 of these candidates. Results: Of 69 anaphylaxis patients enrolled, 36 (52%) had severe reactions, and 38 (55%) were female. Increases in both mRNA and protein of IL-10, S100A9, MMP9, and TREM1 were observed. OSM , S100A8 , TLR4 , and CD64 were upregulated and IL-6 protein concentrations were increased during anaphylaxis. Both FASL and soluble Fas ligand decreased during anaphylaxis. Conclusion: These results provide evidence for the involvement of innate immune pathways and myeloid cells during human anaphylaxis, validating previous microarray findings. Elevated S100A8 , S100A9 , TLR4 , and TREM1 expression, and increased S100A9 and soluble TREM1 protein concentrations strongly suggest that neutrophils are activated during acute anaphylaxis.