[Early transcriptomic features of neutrophils and monocytes activated by the outer membrane protein MSP2 of anaplasma phagocytophilum]

Objective To investigate the early transcriptomic characteristics of neutrophils and monocytes stimulated by the major surface protein 2 (MSP2) of anaplasma phagocytophilum(AP), to preliminarily explore their functional differences and potential common pro-inflammatory mechanisms of these two cell types in the inflammatory response, and to provide a theoretical basis for understanding the inflammatory pathogenesis of Human Granulocytic Anaplasmosis (HGA) and for developing anti-inflammatory strategies. Methods HL60 cells (rHL60) differentiated with dimethyl sulfoxide (DMSO) for 8 days were used as a neutrophil-like cell model, and human acute monocytic leukemia (THP-1) cells were used as a monocyte model. Both cells were stimulated with recombinant MSP2 (rMSP2) for 2 hours. Differentially expressed genes (DEGs) were identified by transcriptome sequencing, and their biological functions and related signaling pathways were analyzed via Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment. The mRNA expression levels of key DEGs were validated by real-time quantitative PCR (qPCR), and the concentrations of cytokines in cell supernatants were measured by ELISA. Results Transcriptome analysis showed that in rHL60 cells, DEGs were mainly enriched in inflammation. qPCR confirmed the up-regulation of C-C motif chemokine receptor 7 (CCR7) and oxidized low-density lipoprotein receptor 1 (OLR1), while CD1D molecule and C-X-C motif chemokine receptors 1/2 (CXCR1/2) were down-regulated. In THP-1 cells, DEGs were primarily enriched in transcriptional regulation. qPCR validated the up-regulation of nuclear factor kappa B inhibitor zeta (NFKBIZ) and nuclear receptor subfamily 4 group A member 3 (NR4A3), whereas thioredoxin-interacting protein (TXNIP) and interleukin-16 (IL-16) were down-regulated. ELISA results demonstrated that both cell types significantly secreted C-C motif chemokine ligands 3/4/20 (CCL3/4/20) following MSP2 stimulation. Conclusion In the early phase of MSP2 stimulation, neutrophils serve as the primary cells initiating the inflammatory response, whereas monocytes focus on immune regulation. The co-secretion of CCL3, CCL4, and CCL20 may represent a potential molecular mechanism by which these two innate immune cell types jointly promote inflammatory responses during AP infection.