A novel anti-inflammatory phenotype transformed by repetitive low-dose lipopolysaccharide in primary peritoneal tissue-resident macrophages

Abstract

Background/Aim: Our previous studies suggested that oral administration of lipopolysaccharide (LPS) regulates the progression of various diseases via transformation of tissue-resident macrophages (Mφ). Recently, we characterized microglia transformed by repetitive low-dose LPS treatment (REPELL-microglia) in vitro, and this response was similar to that observed in response to oral administration of LPS in vivo. Here, we examined the characteristics of peritoneal tissue-resident MÖ (pMφ) transformed by repetitive low-dose LPS treatment (REPELL-pMφ). Materials and Methods: Primary pMφ were treated with low-dose LPS (1 ng/ml) three times; subsequently, phagocytic activity and gene expression were evaluated. Results: REPELL-pMφ exhibited high phagocytic activity and elevated expression of Arg1, Gipr, Gdnf, and Fpr2. The gene expression profiles observed in REPELL-pMφ were distinct from those of REPELL-microglia. Conclusion: REPELL-pMφ have the potential to promote clearance of xenobiotics and to suppress inflammation. The present study also demonstrates the diversity of tissue-resident Mφ transformation that reflect their tissue origin.