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Removal of circulating mitochondrial N-formyl peptides via immobilized antibody therapy restores sepsis-induced neutrophil dysfunction.

Woon Yong KwonYoon Sun JungGil Joon SuhSung Hee KimAreum LeeJeong Yeon KimHayoung KimHeesu ParkJieun ShinTaegyun KimKyung Su KimKiyoshi ItagakiCarl J Hauser
Published in: Journal of leukocyte biology (2024)
During recovery from septic shock, circulating mitochondrial N-formyl peptides (mtFPs) predispose to secondary infection by occupying formyl peptide receptor 1 (FPR1) on the neutrophil (polymorphonuclear leukocyte, PMN) membrane, suppressing cytosolic calcium ([Ca2+]i)-dependent responses to secondarily encountered bacteria. However, no study has yet investigated therapeutic clearance of circulating mtFPs in clinical settings. Thus, we studied how to remove mtFPs from septic-shock plasma and whether such removal could preserve cell-surface FPR1 and restore sepsis-induced PMN dysfunction by normalizing [Ca2+]i flux. In in vitro model systems, mtFP removal rescued PMN FPR1-mediated [Ca2+]i flux and chemotaxis that had been suppressed by prior mtFP exposure. However, PMN functional recovery occurred in a stepwise fashion over 30 - 90 minutes. Intracellular Ca2+-calmodulin appears to contribute to this delay. In ex vivo model systems using blood samples obtained from patients with septic shock, anti-mtFP antibodies alone failed to eliminate mtFPs from septic-shock plasma or inhibit mtFP activity. We therefore created a beads-based anti-mtFP antibody cocktail (bb-AMfpA) by combining protein A/sepharose with antibodies specific for the most potent human mtFP chemoattractants. The bb-AMfpA treatment successfully removed those active mtFPs from septic-shock plasma. Furthermore, the bb-AMfpA treatment significantly restored chemotactic and bactericidal dysfunction of PMNs obtained from patients with septic shock who developed secondary infections. By clearing circulating mtFPs, the immobilized anti-mtFP antibody therapy prevented mtFP interactions with surface FPR1, thereby restoring [Ca2+]i-dependent PMN antimicrobial function in clinical septic-shock environments. This approach may help prevent the development of secondary, nosocomial infections in patients recovering from septic shock.
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