Optimized rAAV8 targeting acinar KLF4 ameliorates fibrosis in chronic pancreatitis via exosomes-enriched let-7s suppressing pancreatic stellate cells activation

Chronic pancreatitis (CP) is marked by progressive fibrosis and the activation of pancreatic stellate cells (PSC), accompanied by the destruction of pancreatic parenchyma, leading to the loss of acinar cells (ACs). Few researches explored the mechanism by which damaged ACs (DACs) contribute to PSC activation and pancreatic fibrosis. Currently, there are no effective drugs for curing CP or limiting the progression of pancreatic fibrosis. In this research, co-culture with intact acinar cells (IACs) suppressed PSC activation, while co-culture with DACs did the opposite. Krüppel-like factor 4 (KLF4) was significantly upregulated in DACs and was established as the key molecule that switches ACs from PSC-suppressor to PSC-activator. We revealed the exosomes of IACs contributed to the anti-activated function of IACs-CS on PSC. MiRNome profiling showed that let-7 family is significantly enriched in IACs-derived exosomes (>30% miRNome), which partially mediates IACs' suppressive impacts on PSC. Furthermore, it has been observed that the enrichment of let-7 in exosomes was influenced by the expression level of KLF4. Mechanistic studies demonstrated that KLF4 in ACs upregulated Lin28A, thereby decreasing let-7s levels in ACs-derived exosomes, and thus promoting PSC activation. We utilized an adeno-associated virus specifically targeting KLF4 in ACs (shKLF4-pAAV) to suppress PSC activation in CP, resulting in reduced pancreatic fibrosis. IACs-derived exosomes hold potential as potent weapons against PSC activation via let-7s, while activated KLF4/Lin28A signaling in DACs diminished such functions. ShKLF4-pAAV holds promise as a novel therapeutic approach for CP.