#753 Targeted anti-IL-1β bacteroides fragilis outer membrane vesicles alleviate inflammatory injury in diabetic nephropathy

Abstract Background and Aims It is accepted that diabetic nephropathy (DN) is not only a disease caused by impaired glucose metabolism, but also a chronic inflammatory disease. The interleukin-1β (IL-1β) plays an important role in inflammation-mediated renal injury in DN. IL-1β blocking therapy can prevent inflammatory cytokine-mediated kidney injury. However, the high cost and systemic side effects of IL-1β antibodies limit its application. Therefore, firstly this study aimed to construct kidney-targeting outer membrane vesicles (OMVs) of Bacteroides fragilis loaded with IL-1β single-chain variable fragment (scFv). These OMVs derived from human commensal non-toxigenic Bacteroides fragilis have been proven to play an immunosuppressive role in the intestine and distant organs. This targeted drug delivery platform built with this as a carrier is expected to relieve kidney inflammation in the development of DN. Methods We recombinantly expressed the scFv based on the Gevokizumab sequence in Escherichia coli, and loaded it into the OMVs derived from Bacteroides fragilis by multiple ultrasounds. The targeting peptide with the sequence (KKEEE)3{Lys(N3)} was connected to the membrane surface through a copper-free catalyzed click chemistry reaction. The package, which consisted of OMVs and the scFv targeting IL-1β in the kidney (OMV-KTP-scFv) was obtained. OMV-KTP-scFv treated in HK-2 cells and healthy mice respectively, and evaluated its in vitro and in vivo drug safety. The concentration of IL-1β scFv in blood and kidney tissues at different time points were measured using streptozotocin (STZ)-induced diabetic mice. DID-labeled OMVs was used for ex vivo infrared imaging of various organs to evaluate the delivery efficiency of the targeted carrier. In vitro, OMV-KTP-scFv was used to prevent inflammation in mouse primary renal tubular epithelial cells induced by high glucose, and in vivo to alleviate kidney injury in STZ-induced diabetic mice. Results We successfully prepared OMV-KTP-scFv and confirmed the co-localization of OMVs, KTP, and scFv using super-resolution microscopy. The prepared OMV-KTP-scFv had high stability, effectively extended the plasma half-life of scFv, and could deliver scFv accurately to the proximal renal tubules. Furthermore, OMV-KTP-scFv also had good safety in vitro and in vivo, and no obvious biotoxicity was found during long-term in vivo administration. In addition, our results show that OMV-KTP-scFv significantly inhibited the expression of inflammatory factors in renal tubular cells of DN, reduced the infiltration of renal interstitial inflammatory cells, and alleviated renal tubular injury. Conclusion Our findings demonstrated that OMVs of Bacteroides fragilis targeting the kidney can deliver the IL-1β scFv to the renal tubulointerstitium and reduce the renal interstitial injury in DN by antagonizing local inflammation.