Extracellular Hsp70 Is Involved in the CXCL12/CXCR4 Pathway in Primary Human Nasal Epithelial Cells: A Preliminary Study.

Background and Objectives: To date, no studies have been conducted on the interaction between extracellular heat shock protein 70 (Hsp70) and C-X-C chemokine receptor type 4 (CXCR4) in the upper airway. We aimed to evaluate the relationship between extracellular Hsp70 and CXCR4 and their role in the primary human nasal epithelium. Methods: We cultured primary human nasal epithelial (HNE) cells in an air-liquid interface. Macrogen performed single-cell quantitative polymerase chain reaction and sequencing. We conducted western blot analysis for the CXCR4 and mitogen-activated protein kinase (MAPK) pathways. Results: Extracellular Hsp70 treatment significantly increased the genetic expression and protein levels of CXCR4 in primary HNE cells. Phospho-ERK expression was increased by cotreatment with Hsp70 and CXCL12, but inhibited by pretreatment with AMD3100, a CXCR4 inhibitor. Pretreatment with an anti-Hsp70 antibody reduced phospho-ERK expression upregulation induced by cotreatment with Hsp70 and CXCL12. Conclusion: Extracellular Hsp70 participates in the activation of the CXCR4-dependent downstream signaling pathway in HNE cells. Further studies should evaluate the extracellular Hsp70-CXCL12/CXCR4 axis and the role of its components in the development of inflammatory diseases.