An opsonic peptide speeds clearance of radiation-induced macrophage extracellular traps in cell culture

Summary. Researchers at the Feinstein Institutes for Medical Research in the United States reported in Frontiers in Immunology, published online on 12 October, laboratory experiments with an opsonic peptide they call OP18. Ionizing radiation can trigger inflammation in which macrophage extracellular traps (METs) are implicated. OP18 was designed to bind several damage-associated molecular patterns (DAMPs), including histone H3 and high-mobility group box 1 protein (HMGB1), which are also present in METs. The authors asked whether OP18 would help cultured macrophages take up radiation-associated METs and whether that uptake would change inflammatory readouts in the same cell system.

Research context (RUO). In vitro, OP18 increased MET uptake by macrophages in a manner that depended on αvβ3 integrin and involved endo-lysosomal trafficking. Enhanced clearance was linked to less MET-driven mitochondrial stress and to restored measures of metabolic function such as ATP production and basal and maximal respiration. The peptide also showed a trend toward lower MET-induced NF-κB activation and higher release of the anti-inflammatory cytokine IL-10. The work is cell-culture research; it does not report a clinical trial or a human-use recommendation. For peptide researchers, it is a mechanistic example of how a short opsonic peptide can be used as a laboratory tool to study DAMP and MET clearance pathways in macrophages after radiation exposure.