Chrono-pharmacological Targeting of the CCL2-CCR2 Axis Ameliorates Atherosclerosis

Abstract

Onset of cardiovascular complications as a consequence of atherosclerosis exhibits a circadian incidence with a peak in the morning hours. Although development of atherosclerosis extends for long periods of time through arterial leukocyte recruitment, we hypothesized that discrete diurnal invasion of the arterial wall could sustain atherogenic growth. Here, we show that myeloid cell recruitment to atherosclerotic lesions oscillates with a peak during the transition from the activity to the resting phase. This diurnal phenotype is regulated by rhythmic release of myeloid cell-derived CCL2, and blockade of its signaling abolished oscillatory leukocyte adhesion. In contrast, we show that myeloid cell adhesion to microvascular beds peaks during the early activity phase. Consequently, timed pharmacological CCR2 neutralization during the activity phase caused inhibition of atherosclerosis without disturbing microvascular recruitment. These findings demonstrate that chronic inflammation of large vessels feeds on rhythmic myeloid cell recruitment, and lay the foundation for chrono-pharmacology-based therapy.

Circadian Features of Neutrophil Biology

“…For example, disruption of Bmal1 in club cells and adrenalectomy in the context of circadian recruitment of neutrophils to lungs after LPS revealed blunted glucocorticoid signaling, non-rhythmic expression of CXCL5, neutrophilia and antimicrobial responses (65). Other studies tested the possibility of targeting the circadian properties of neutrophils and monocytes in atherosclerosis, by showing arterial-and time-specific repression of leukocyte recruitment to plaques upon inhibition of CCR2 (81). Timed CCR2 blocking at nighttime (ZT17) decreased arterial myeloid cell recruitment and atherosclerotic lesion formation, whereas the neutralization at daytime (ZT5) had no effect, suggesting again the importance of chrono-pharmacology-based approaches (81).…”

“…Other studies tested the possibility of targeting the circadian properties of neutrophils and monocytes in atherosclerosis, by showing arterial-and time-specific repression of leukocyte recruitment to plaques upon inhibition of CCR2 (81). Timed CCR2 blocking at nighttime (ZT17) decreased arterial myeloid cell recruitment and atherosclerotic lesion formation, whereas the neutralization at daytime (ZT5) had no effect, suggesting again the importance of chrono-pharmacology-based approaches (81). Finally, targeting pro-migratory factors VCAM-1, ICAM-1 and CD49d during inflammatory challenge with LPS affected neutrophil trafficking and blunted inflammation (71).…”

Circadian Regulation of Immunity Through Epigenetic Mechanisms

“…Indeed, 24-h rhythms in immune cell trafficking have further consequences both in disease and treatment. For example, myeloid cell recruitment to atherosclerotic lesions oscillates, presenting a peak at the onset of the resting phase, while myeloid cell adhesion to microvascular beds happens with opposite phase (Winter et al, 2018). Hence, time-of-day specific inhibition of leukocyte recruitment provides means to treat atherosclerotic lesions without affecting inflammatory processes in the microcirculation (Winter et al, 2018).…”

“…For example, myeloid cell recruitment to atherosclerotic lesions oscillates, presenting a peak at the onset of the resting phase, while myeloid cell adhesion to microvascular beds happens with opposite phase (Winter et al, 2018). Hence, time-of-day specific inhibition of leukocyte recruitment provides means to treat atherosclerotic lesions without affecting inflammatory processes in the microcirculation (Winter et al, 2018). In this scenario, it would be interesting to determine which epigenetic components of the circadian clock are involved in mediating time of day-specific immune cell trafficking and recruitment, as they could provide new therapeutic targets for diseases involving the immune system, and foundation to design chronotherapeutic strategies.…”

Time-of-Day-Dependent Trafficking and Function of Leukocyte Subsets

“…In murine models of induced atherosclerosis using Apoe À/À mice on a high-fat diet, the adhesion and invasion of neutrophils and monocytes into atherosclerotic plaques depends on CCR2 and exhibits a daily rhythm, peaking in the morning in mice [48,49]. Moreover, rhythmic expression of the corresponding chemokine CCL2 in neutrophils is relevant in this scenario, and this depends on myeloid BMAL1 [49].…”