Erythrocyte membrane-camouflaged JAK1 inhibitor for the treatment of hemophagocytic lymphohistiocytosis

Abstract Background: Hemophagocytic lymphohistiocytosis (HLH) is a hyperinflammatory syndrome driven by aberrantly activated macrophages, which trigger downstream immune cascades. While JAK1 is widely expressed on immune cells and implicated in inflammatory signaling, current JAK receptor inhibitors show limited efficacy as monotherapies. Although these inhibitors suppress IFN-γ production by T/NK cells, persistent macrophage activation via Toll-like receptors (TLRs) or complement signaling may sustain hemophagocytosis. Thus, targeting hyperactivated macrophages is critical for HLH treatment. Given the unique erythrophagocytosis in HLH, erythrocyte-based delivery of JAK inhibitors to splenic macrophages may offer a superior therapeutic strategy. Notably, erythrocytes also function as immune cells and participate in immune regulation. Erythrocytes express TLR9 which binds CpG to attenuate systemic inflammation, while TLR9-stimulated erythrocytes further suppress macrophage overactivation through NF-κB pathway regulation. The erythrocyte membrane possesses both targeting capability and immunomodulatory functions, offering a novel therapeutic strategy for HLH. And to our knowledge, this is the first nanoplatform simultaneously leveraging erythrocytes' drug delivery capacity and intrinsic immunomodulatory properties for HLH. Methods and results: We first investigated the therapeutic effect of the JAK1 inhibitor Golidocitinib (DZD), a novel JAK1 receptor inhibitor on HLH. The HLH model was established via CpG-ODN injection and mice were treated with Ruxolitinib and DZD. The inflammatory markers were collected to evaluate the efficacy of DZD in HLH treatment. The results showed that DZD treatment demonstrate superior efficacy in reducing splenomegaly (p < 0.01) and elevating erythrocytes (p < 0.001) and leukocyte (p < 0.01) counts compared to Ruxolitinib. We then engineered erythrocyte membrane-camouflaged DZD nanoparticles (mn@DZD) and evaluated their therapeutic efficacy in an HLH murine model. The characterization was performed using TEM and particle size analysis, which confirmed the successful coating of erythrocyte membranes on the nanoparticle surface. The nanoparticles exhibited a uniform size distribution (135 ± 3.2 nm) with a drug encapsulation efficiency of 45.2 ± 2.1%. The HLH model was established via CpG-ODN injection and was randomly divided into groups and treated with the following: PBS (control), mnano (blank), DZD, n@DZD, and mn@DZD. The results showed that mn@DZD significantly reduced splenomegaly (spleen weight decreased from 20.62 ± 0.82 mg to 14.40 ± 0.60 mg; p < 0.001), as well as increasing erythrocyte and leukocyte counts. Mice in the mn@DZD treatment group exhibited more stable body weight maintenance, with untreated mice showing 1.1-fold greater weight decrease compared to the treated group (p < 0.001). and lowered serum triglycerides and liver enzymes (p < 0.01). Flow cytometric analysis of splenocytes revealed significant reductions in activated antigen-presenting cells (APCs) (MHC-II+CD86+CD80+), macrophages (CD11b+F4/80+), M1-polarized macrophages (F4/80+CD86+), and activated T cells (p < 0.01). Conclusion: Erythrocyte membrane-camouflaged JAK1 inhibitor shows efficacy and safety in murine HLH model. This erythrocyte-mimetic platform based on bionic principles demonstrates strong translational potential for targeted splenic delivery in HLH.