Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening clinical syndrome with poor prognoses. Clinical manifestations typically include fever, trilineage cytopenia, hepatosplenomegaly, hemophagocytosis, and hypercytokinemia, culminating in multiorgan dysfunction and failure (Al-Samkari and Berliner, 2018). HLH classification distinguishes primary HLH, arising from genetic defects, from secondary HLH, resulting from underlying factors, including infection, autoimmune disease, or malignancy. HLH is characterized by a positive feedback loop between the cytokine storm and macrophage overactivation (Vick et al., 2017). Current therapeutic regimens, notably the extensively employed HLH-94 and DEP (doxorubicin-etoposide-methylprednisolone) protocols, include immunosuppressive glucocorticoids and chemotherapeutic agents that mitigate activated lymphocyte and macrophage populations and dampen cytokine storms (Wang et al., 2015, Johnson et al., 2014). However, the mortality rate remains at approximately 50 % (Trottestam et al., 2011, Henter et al., 2002), and the utilization of the HLH-94 and DEP regimens is constrained by adverse effects, including gastrointestinal bleeding and therapy-related leukemia (Zhang et al., 2021). Consequently, there is a pressing need to develop more efficacious strategies against HLH with fewer side effects.

Targeted inflammation modulation is emerging as a promising approach for the treatment (Henderson and Degar, 2022). Noteworthy successes have been achieved in clinical applications of antibodies targeting specific cytokines, including IL-6, IL-1β, and IFN-γ (Vick et al., 2017). However, antibodies are expensive and can only neutralize specific cytokines, which may impede their adequacy in addressing the complex cytokine storm involved in HLH (Fajgenbaum and June, 2020). Downstream of several cytokines involved in HLH, the JAK/STAT signaling pathway presents an attractive therapeutic target to simultaneously abrogate the signaling of multiple cytokine pathways. Ruxolitinib (Rux), a JAK1/2 inhibitor, has been reported to increase HLH remission rate when combined with HLH-94 or DEP protocol (Wang et al., 2020, Wang et al., 2021). Nevertheless, Rux monotherapy efficacy for HLH remains suboptimal (Ahmed et al., 2019, Wang et al., 2020). Oral administration in critically ill patients may lead to intolerance or altered absorption. A Rux delivery platform is expected to address these challenges and enhance therapeutic outcomes in HLH treatment.

Diverse nanoplatforms are available for drug delivery, including exosomes (Zhu et al., 2020, Zhu et al., 2022) and liposomes (Chen et al., 2023). Biomimetic nanomedicines have attracted increasing attention due to their ability to inherit the source cell properties. Red blood cell membrane-coated nanoparticles can prolong circulation time by reducing non-specific uptake by the mononuclear phagocytic system (Hu et al., 2011). Platelet membranes can endow nanoparticles with the ability to target tumors or inflammation sites owing to the intrinsic affinity of platelets for these sites (Zhang et al., 2022, Ma et al., 2020). Additionally, nanoparticles coated with the cell membranes of inflammatory cells, including neutrophils or macrophages, have been utilized to bind and neutralize inflammatory cytokines, offering therapeutic benefits in conditions, including rheumatoid arthritis or sepsis (Zhang et al., 2018, Thamphiwatana et al., 2017). Our research group has previously developed macrophage membrane-coated nanoparticles to sponge diverse types of inflammation cytokines, such as IFN-γ and IL-6, demonstrating efficacy in HLH treatment (Wang et al., 2023). Additionally, it is believed that the lipophilic core of polyester nanoparticles could load lipophilic Rux with a high drug-loading capacity, and overactivated macrophages could more efficiently engulf nanoparticles than their resting counterparts. Therefore, Rux-loaded macrophage membrane-coated nanoparticles hold promise not only for extracellular cytokine sequestration, but also for targeted Rux delivery to overactivated macrophages. This targeted delivery aims to enhance the inhibitory effect on the intracellular JAK/STAT pathway while concurrently mitigating the potential cytopenic side effects associated with Rux administration (Marcuzzi et al., 2022).

In this study (Scheme 1), we developed a novel strategy for HLH management by using Rux-loaded macrophage membrane-coated polyester nanoparticle (M@NP-R). Firstly, M@NP-R can directly sponge diverse types of inflammatory cytokines to alleviate extracellular cytokine storms and reduce macrophage activation induced by cytokines. Secondly, it exhibited a proclivity for delivering Rux to overactivated macrophages to suppress macrophage activation and proliferation by effectively inhibiting the intracellular JAK/STAT signaling pathway and cytokine production. These dual mechanisms could synergistically enhance M@NP-R therapeutic efficacy for HLH treatment by sponging extracellular cytokines and inhibiting intracellular cytokine production. The effect of M@NP-R on macrophage activation and proliferation was investigated both in vitro and in vivo using flow cytometry and cytokine measurements. The therapeutic potential of M@NP-R was evaluated in CpG-induced mild HLH and lethal HLH mouse models induced by poly(I:C) plus lipopolysaccharide (LPS) treatment.