Role of Lyve1+ Macrophages in Angiogenesis and Tissue Remodelling

Lyve1+ macrophages play an important role in angiogenesis during wound healing and tissue remodelling of the injured dental pulp tissue, according to a recent study published in the Scientific Reports.

Tissue-resident macrophages populate every tissue, playing important roles in support of tissue development, homeostasis, and remodeling, which makes them attractive therapeutic targets. The functions and phenotypes of tissue-resident macrophages are extremely heterogeneous, depending on the ontogeny, local microenvironment, and inflammation status of the tissue in which they reside. Tissue-resident macrophages expressing lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1) are found in multiple tissues and organs.

Research Objectives and Findings

The researchers aimed to evaluate the dynamics and biological functions of LYVE-1+ macrophages in the dental pulp during post-injury tissue remodelling. Immunofluorescence staining of mouse embryos revealed that LYVE-1+ macrophages colonized dental pulp before birth.

In mature rat molar dental pulp, LYVE-1+ macrophages were the main subset of macrophages expressing CD163, an M2 marker, and were distributed throughout the tissue. In response to dental pulp injury induced by cavity preparation, LYVE-1+ macrophages quickly disappeared from the affected area of the pulp and gradually repopulated during the wound healing process.

Experimental Results

• Mouse macrophages cultured with a mixture of macrophage colony-stimulating factor, interleukin-4, and dexamethasone increased LYVE-1 expression, whereas lipopolysaccharide-stimulation decreased LYVE-1 expression.
• Enforced expression of Lyve1 in RAW264.7 cells resulted in increased mRNA expression of matrix metalloproteinase 2 (Mmp2), Mmp9, and vascular endothelial growth factor A (Vegfa).
• Lyve1-expressing macrophages promoted the migration and tube formation of human umbilical vein endothelial cells.

Conclusion

Thus, in conclusion, the study suggests that LYVE-1+ tissue-resident M2-like macrophages in dental pulp showed dynamism in response to pulp injury, and possibly play an important role in angiogenesis during wound healing and tissue remodelling.

Reference

Kinetics of LYVE-1-positive M2-like macrophages in developing and repairing dental pulp in vivo and their pro-angiogenic activity in vitro by Thoai Quoc Kieu, et al. published in the Scientific Reports.

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