Brutons tyrosine kinase inhibitor Zanubrutinib modulates Fc gamma receptors to inhibit platelet destruction for alleviation of refractory immune thrombocytopenia

Background Primary immune thrombocytopenia (ITP) is an autoimmune disorder characterized by low platelet count (PLT). Bruton tyrosine kinase (BTK) is a therapeutic target in immune-mediated diseases. This study aimed to evaluate the effects of a BTK inhibitor, zanubrutinib (Zan), on refractory ITP.Methods Peripheral blood was collected from healthy controls (HC) and refractory ITP patients (n = 15), and peripheral blood mononuclear cell (PBMC) extraction was performed. The proportion of myeloid-derived suppressor cells (MDSCs) in PBMCs and Arg-1, iNOS, Fc gamma receptor (FcγR), GPIIb/IIIa, and GPIb/IX autoantibody levels were measured. ITP monocytes were separated into control (Con), Zan (Zan), dexamethasone (DXM), and combination (Zan + DXM) groups. Detection ophagocytosis and platelet activation by flow cytometry; FcγR expression by qRT-PCR and western blot; and IFN-γ, IL-4, IL-2, and IL-10 levels were determined by ELISA.Results PBMCs from the ITP group demonstrated lower MDSCs proportions and Arg-1 levels, but higher iNOS, FcγRIII, FcγRIIb, FcγRI, GPIIb/IIIa, and GPIb/IX autoantibody levels than those in the HC group. Following Zan intervention, ITP monocytes exhibited decreased phagocytosis, FcγRIIa, FcγRI protein, IFN-γ, IL-2, p-mTOR/mTOR levels, and increased FcγRIIb, PLTs, IL-4, PAC-1, and CD62p levels.Conclusion Zan may modulate FcγR toward FcγRIIb to inhibit platelet destruction, thereby improving refractory ITP.