Lysozyme M–Positive Monocytes Mediate Angiotensin II–Induced Arterial Hypertension and Vascular Dysfunction

Abstract

Angiotensin II (1 mg · kg(-1) · d(-1) for 7 days) increased the number of both CD11b(+)Gr-1(low)F4/80(+) macrophages and CD11b(+)Gr-1(high)F4/80(-) neutrophils in mouse aorta (verified by flow cytometry). Selective ablation of lysozyme M-positive (LysM(+)) myelomonocytic cells by low-dose diphtheria toxin in mice with inducible expression of the diphtheria toxin receptor (LysM(iDTR) mice) reduced the number of monocytes in the circulation and limited ATII-induced infiltration of these cells into the vascular wall, whereas the number of neutrophils was not reduced. Depletion of LysM(+) cells attenuated ATII-induced blood pressure increase (measured by radiotelemetry) and vascular endothelial and smooth muscle dysfunction (assessed by aortic ring relaxation studies) and reduced vascular superoxide formation (measured by chemiluminescence, cytochrome c assay, and oxidative fluorescence microtopography) and the expression of NADPH oxidase subunits gp91(phox) and p67(phox) (assessed by Western blot and mRNA reverse-transcription polymerase chain reaction). Adoptive transfer of wild-type CD11b(+)Gr-1(+) monocytes into depleted LysM(iDTR) mice reestablished ATII-induced vascular dysfunction, oxidative stress, and arterial hypertension, whereas transfer of CD11b(+)Gr-1(+) neutrophils or monocytes from gp91(phox) or ATII receptor type 1 knockout mice did not. CONCLUSIONS- Infiltrating monocytes with a proinflammatory phenotype and macrophages rather than neutrophils appear to be essential for ATII-induced vascular dysfunction and arterial hypertension.