PLAG enhances macrophage mobility for efferocytosis of apoptotic neutrophils via membrane redistribution of P2Y2

Abstract

Neutrophil activity, including trapping of damage-associated molecular patterns by neutrophil extracellular traps (NETs), is an important response to microbial infection. Most activated neutrophils commit to apoptosis and are removed by activated macrophages in the process of efferocytosis. Improper clearance of apoptotic neutrophils often causes an unnecessary and exaggerated immune response and subsequent chronic inflammation. Effective macrophage mobility toward activated neutrophils, which is triggered by binding of 'find-me' signals to receptors such as P2Y2, is a crucial step for the timely clearance of apoptotic neutrophils. In this paper, we investigated the effect of 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG) on efferocytosis and the underlying molecular mechanisms. In a coculture of apoptotic neutrophils with macrophages, PLAG treatment increased levels of efferocytosis of apoptotic neutrophils. PLAG induced faster translocation of P2Y2 from lipid rafts to nonlipid raft plasma membrane domains in macrophages. This repositioning of P2Y2 enables the polarization of the cytoskeleton by association of the receptor with cytoskeletal proteins such as a-tubulin and actin to improve the mobility of macrophages. The formation of vesicular, chylomicron-like structures by PLAG was a prerequisite for the induction of this macrophage activity, as none of these effects was seen when the vesicle receptor GPIHBP1 was absent. Taken together, these data showed that PLAG is a powerful immune resolvent that triggers the prompt clearance of apoptotic neutrophils by enhanced efferocytosis activity. PLAG could therefore be an effective lipid-based efferocytosis enhancer for use as a therapeutic drug to prevent inflammatory disease caused by uncontrolled immune responses.

1-Palmitoyl-2-Linoleoyl-3-Acetyl-rac-Glycerol (PLAG) Mitigates Monosodium Urate (MSU)-Induced Acute Gouty Inflammation in BALB/c Mice

“…For resolution of gouty inflammation, macrophages perform essential process called efferocytosis to eliminate dead neutrophils and aggregated NETs. We already verified that PLAG promotes macrophage efferocytosis by enhancing macrophage mobility via membrane redistribution of P2Y2 (67). From the results, we expect that PLAG can help resolving of acute gouty inflammation by promoting efferocytosis.…”

1‑Palmitoyl‑2‑linoleoyl‑3‑acetyl‑rac‑glycerol ameliorates EGF‑induced MMP‑9 expression by promoting receptor desensitization in MDA‑MB‑231 cells

“…PLAG therapy has been shown to mitigate the effects of various diseases. Recent reports have documented that PLAG controlled neutrophil recruitment by regulating the trafficking of Toll-like receptors and enhanced efferocytosis through membrane redistribution of G protein-coupled receptors (45,46). We believe that these published studies have shown the ability of PLAG to modulate the movement of receptors, thus we hypothesized that PLAG may also modulate the trafficking of receptor tyrosine kinases (RTKs).…”

Efferocytosis and Its Role in Inflammatory Disorders

“…Neutrophils can be inactivated via apoptosis, forming apoptotic cells that are removed by tissue-resident macrophages through an efferocytotic mechanism (Maimon et al, 2020;Sekheri et al, 2020). It was reported that culture of macrophages or monocytes with apoptotic neutrophils increased the levels of IL-10 and TGF-β (Kim et al, 2019), while their engulfment enhanced the release of specialized pro-resolving mediators, such as lipoxin B4 and resolvin 1/2, indicating the potential anti-inflammatory action of apoptotic neutrophils (Sun et al, 2015;Moges et al, 2018). Additionally, neutrophil efferocytosis guided by phagocytic signals was found to be regulated by urokinase receptorassociated procedures (Park et al, 2009).…”