The Peptide–Drug Conjugate M1pep–Tasquinimod Ameliorates Acute Pancreatitis via Selectively Clearing M1-like Macrophages

M1-like macrophages dominate local and systemic inflammatory response progression in acute pancreatitis (AP). The development of strategies to target pro-inflammatory M1-like macrophages in conjunction with primary pathophysiology-specific pharmacological therapy presents a challenge in the management of AP. Peptide–drug conjugates (PDCs), which are emerging second-generation conjugate drugs, have quickly become a new favorite in the field of targeted drug delivery due to their superior drug bioavailability, affinity, and stability. Tasquinimod (Tasq) is a specific inhibitor of S100A9 that is expressed mainly in M1-like macrophages during AP. Drug repositioning revealed that Tasq improved AP in a dose-dependent manner, but drug toxicity occurred at doses of 30 mg/kg. Therefore, we selected 2 specific M1-like macrophage-binding peptides (M1peps) by phage display technology and developed a novel PDC, M1pep-Tasq, by connecting M1peps to activated Tasq with a cleavable linker. Based on a mouse model of AP constructed by retrograde injection of sodium taurine cholate into the bile pancreatic duct and an M1-like macrophage polarization model induced by lipopolysaccharide + interferon-γ stimulation, we confirmed that M1pep-Tasq reduces the drug toxicity of Tasq and improves its efficacy by enhancing the targeting of Tasq to damaged organs in vivo and to M1-like macrophages in vitro. Furthermore, M1pep-Tasq effectively improves AP by inhibiting M1-like macrophage polarization by suppressing the S100A9–TLR4–MAPK pathway. Overall, we have developed a novel PDC, M1pep-Tasq, with promising applications in clinical settings to treat a range of inflammatory disorders by increasing the efficacy and reducing the toxicity of Tasq.