Age-related arterial immune cell infiltration in mice is attenuated by caloric restriction or voluntary exercise

Abstract

Age-related arterial inflammation is associated with dysfunction of the arteries and increased risk for cardiovascular disease. To determine if aging increases arterial immune cell infiltration as well as the populations of immune cells principally involved, we tested the hypothesis that large elastic and resistance arteries in old mice would exhibit increased immune cell infiltration compared to young controls. Additionally, we hypothesized that vasoprotective lifestyle interventions such as lifelong caloric restriction or 8weeks of voluntary wheel running would attenuate age-related arterial immune cell infiltration. The aorta and mesenteric vasculature with surrounding perivascular adipose was excised from young normal chow (YNC, 4-6months, n=10), old normal chow (ONC, 28-29months, n=11), old caloric restricted (OCR, 28-29months, n=9), and old voluntary running (OVR, 28-29months, n=5) mice and digested to a single cell suspension. The cells were then labeled with antibodies against CD45 (total leukocytes), CD3 (pan T cells), CD4 (T helper cells), CD8 (cytotoxic T cells), CD19 (B cells), CD11b, and F4/80 (macrophages) and analyzed by flow cytometry. Total leukocytes, T cells (both CD4 and CD8 subsets), B cells, and macrophages in both aorta and mesentery were all 5- to 6-fold greater in ONC compared to YNC. Age-related increases in T cell (both CD4 and CD8), B cell, and macrophage infiltration in aorta were abolished in OCR mice. OVR mice exhibited 50% lower aortic T cell and normalized macrophage infiltration. B cell infiltration was not affected by VR. Age-related mesenteric CD8 T cell and macrophage infiltration was normalized in OCR and OVR mice compared to young mice, whereas B cell infiltration was normalized by CR but not VR. Splenic CD4 T cells from ONC mice exhibited a 3-fold increase in gene expression for the T helper (Th) 1 transcription factor, Tbet, and a 4-fold increase in FoxP3, a T regulatory cell transcription factor, compared to YNC. Splenic B cells and mesenteric macrophages from old mice exhibited decreased proinflammatory cytokine gene expression regardless of treatment group. These results demonstrate that aging is associated with infiltration of immune cells around both the large-elastic and resistance arteries and that the vasoprotective lifestyle interventions, CR and VR, can ameliorate age-related arterial immune cell infiltration.

Selected life-extending interventions reduce arterial CXCL10 and macrophage colony-stimulating factor in aged mouse arteries

“…We have previously found that lifelong CR prevents age-related arterial dysfunction [20, 22] and accumulation of T cells in both aorta and the mesenteric vasculature [35]. In the present investigation, we found that age-related increases CXCL10, which recruits T cells, was prevented by CR.…”

“…We also found that treatment with Rap lowered MCSF, which recruits and serves as a growth factor for macrophages. Consistent with this observation, aortic perivascular macrophages increase with age [10, 35], and Rap treatment improves arterial function in old mice [21]. The finding that some of the lifespan extending interventions can prevent age-related increases in aortic chemokines that mediate differentiation and recruitment of inflammatory cells represents a potential mechanism by which these interventions might preserve arterial health.…”

“…This study is, to our knowledge, the first to show increased production of CXCL9, CXCL10, GMCSF and MCSF in the aged artery. The production of the above cytokines by the artery may contribute to increased arterial immune cell infiltration that has been observed with age [10,35]. Whether these immune cells directly mediate age-related arterial dysfunction is unknown, but both T cells and macrophages are implicated in mediating arterial dysfunction in experimental hypertension [36, 37].…”

Inflammation as a mediator of arterial ageing

“…Furthermore, in vitro monocyte adhesion is blunted in the presence of serum from old caloric‐restricted rats when compared with serum from old rats fed ad libitum (Csiszar et al., ). Caloric restriction also improves PWV and reverses the age‐related increase of MMP9 in mouse large elastic arteries (Donato et al., ), in addition to normalizing age‐related infiltration of aortic T cells, B cells and macrophages (Figure ) and aortic production of the T‐cell‐recruiting chemokine, CXCL10 (Trott et al., , ). Similar effects of caloric restriction on immune cell infiltration was observed in the mesenteric vasculature (Figure ; Trott et al., ).…”

“…Human, mouse Leucocyte recruitment to artery; promotes large artery stiffening (Donato et al, 2008;Wang et al, 2007Wang et al, , 2011 CC motif chemokine ligand 5; otherwise known as RANTES (Trott et al, 2018) T cells N/A Circulation, perivascular adipose…”