Abstract:

Objective: To investigate the immunomodulatory effect of a novel Bruton tyrosine kinase (BTK) inhibitor orelabrutinib, in host macrophages infected with Mycobacterium tuberculosis (MTB). Methods: Human acute monocytic leukemia (THP-1) cells were cultured and differentiated. The differentiated THP-1 cells were infected with Mycobacterium smegmatis (M.smeg) and then treated with different concentrations of orelabrutinib to compare the ability of macrophages to engulf and clear M.smeg. BTK protein expression was knocked down by using siRNA interference technology, and the knockdown effect was verified by Western blotting. The colony-forming unit (CFU) assay was used to measure the clearance ability of macrophages against M.smeg by treated with orelabrutinib. Results: Orelabrutinib significantly inhibited the tyrosine phosphorylation of BTK without changing the level of BTK protein expression. Additionally, the CFU count of M.smeg in macrophages treated with orelabrutinib decreased from 130.0 (120.3-137.5)×10³/ml to 59.0 (55.8-65.3)×10³/ml, with statistical significance (U=0.000, P=0.014). After knocking down BTK protein expression, the bacterial load of M.smeg in macrophages decreased from 52.0 (44.0-61.5)×10³/ml to 25.0 (22.0-28.0)×10³/ml, with statistical significance (U=9.000, P=0.002). Conclusion: BTK plays a crucial role in macrophage functional regulation. As a novel BTK inhibitor, orelabrutinib not only suppresses BTK tyrosine phosphorylation but also significantly enhances the clearance ability of macrophage against M.smeg, providing a new perspective for its potential anti-tuberculosis applications.

Key words: Mycobacterium tuberculosis, Protein-tyrosine kinases, Macrophages, Orelabrutinib