Targeted modulation of Kupffer cell-monocyte communication by engineered extracellular vesicles to alleviate immunological liver injury

Immunological liver injury (ILI) is a severe immune-mediated condition for which current treatments have limited efficacy and tolerability. Here, we delineate the pivotal role of liver-resident macrophages, specifically Kupffer cells (KCs), in ILI pathogenesis and develop an extracellular vesicle (EV)-based strategy to precisely modulate KC-monocyte crosstalk. Using both a concanavalin A–induced experimental autoimmune hepatitis (EAH) model and clinical samples from patients with autoimmune hepatitis (AIH), we identified a profound remodeling of the hepatic macrophage compartment: marked infiltration of monocyte-derived macrophages (MDMs) occurred without significant alteration in KC abundance. Mechanistically, KCs in injured livers acquired a pro-inflammatory phenotype and upregulated secretion of the chemokine CCL2, thereby recruiting CCR2-expressing circulating monocytes and driving their differentiation into MDMs. Notably, neither KC depletion nor systemic CCL2-CCR2 axis inhibition alone fully mitigated hepatocellular injury, indicating that combined suppression of KC activation and monocyte recruitment is required for robust therapeutic efficacy. To this end, we engineered EVs derived from anti-inflammatory M2 macrophages and loaded them with a potent CCR2 inhibitor (designated CCR2i@M2-EVs). Following intravenous administration, these EVs accumulated in the liver, spleen, and bone marrow, and were internalized by both KCs and monocytes. Compared with free CCR2 inhibitor or unloaded M2-EVs, CCR2i@M2-EVs achieved superior functional outcomes: they more effectively suppressed KC activation, reduced CCL2 production, and inhibited monocyte chemotaxis, collectively resulting in significantly greater attenuation of liver injury in EAH mice. Our findings establish dysregulated KC-monocyte communication as a key pathogenic axis in ILI and provide proof-of-concept that EV-mediated co-modulation of this intercellular dialogue represents a rationally designed strategy that offers combined immunomodulatory and chemotaxis-blocking effects. Dysregulated communication between Kupffer cells (KCs) and monocytes drives immunological liver injury (ILI). Depletion of KCs or inhibition of monocyte recruitment only partially reduces liver injury in ILI. Activated KCs in the injured liver secrete the chemokine CCL2 to recruit monocytes and promote their differentiation into monocyte-derived macrophages. Engineered extracellular vesicles (EVs) loaded with a CCR2 inhibitor (CCR2i@M2-EVs) suppress KCs activation and monocyte chemotaxis to alleviate ILI.