Interruption of classic CD40L-CD40 signalling but not of the novel CD40L-Mac-1 interaction limits arterial neointima formation in mice

Abstract

The co-stimulatory immune molecule CD40L figures prominently in a variety of inflammatory conditions including arterial disease. Recently, we made the surprising finding that CD40L mediates atherogenesis independently of its classic receptor CD40 via a novel interaction with the leukocyte integrin Mac-1. Here, we hypothesised that selective blockade of the CD40L-Mac-1 interaction may also retard restenosis. We induced neointima formation in C57/BL6 mice by ligation of the left carotid artery. Mice were randomised to daily intraperitoneal injections of either cM7, a small peptide selectively inhibiting the CD40L-Mac-1 interaction, scM7, a scrambled control peptide, or saline for 28 days. Interestingly, cM7-treated mice developed neointima of similar size compared with mice receiving the control peptide or saline as assessed by computer-assisted analysis of histological cross sections. These data demonstrate that the CD40L-Mac-1 interaction is not required for the development of restenosis. In contrast, CD40-deficient mice subjected to carotid ligation in parallel, developed significantly reduced neointimal lesions compared with respective wild-type controls (2872 ± 843 µm² vs 35469 ± 11870 µm²). Flow cytometry in CD40-deficient mice revealed reduced formation of platelet-granulocyte and platelet-inflammatory monocyte- aggregates. In vitro, supernatants of CD40-deficient platelet-leukocyte aggregates attenuated proliferation and increased apoptosis of smooth muscle cells. Unlike in the setting of atherosclerosis, CD40L mediates neointima formation via its classic receptor CD40 rather than via its recently described novel interaction with Mac-1. Therefore, selective targeting of CD40L-Mac-1 binding does not appear to be a favorable strategy to fight restenosis.

Elevated circulating CD14++CD16+ intermediate monocytes are independently associated with extracardiac complications after cardiac surgery

“…The latter aspect appears particularly relevant for the healing phase after myocardial injury in the heart 24,25 . Novel technologies like single-cell RNA sequencing provided further in-depth insights into the heterogeneity of monocytes in human blood 26 .…”

Platelet extracellular vesicles induce a pro‐inflammatory smooth muscle cell phenotype

“…Platelets furthermore interact with leukocytes initiated by P-selectin-PSGL-1 interactions and reinforced by integrins [4]. Platelets also propagate the inflammatory response by engagement of CD40 and its ligand CD154 (CD40L), mediating the secretion of cytokines in leukocytes and endothelial cells [5,6]. Platelets furthermore facilitate the interaction of leukocytes to exposed smooth muscle cells (SMC) of the denuded vessel wall via the CX 3 CL1-CX 3 CR1 axis [7].…”

T Cell Cosignaling Molecules in Transplantation

“…Thus, while this pathway is likely at play during pathogen infection, the role of DC-derived CD154 in the execution of alloreactive immune responses remains to be determined. Lastly, the discovery that CD154 likely has another binding partner—CD11b (Mac-1) (Okwor et al, 2015; Willecke et al, 2014; Wolf et al, 2011; Zirlik et al, 2007) (Figure 3)—sheds significant light on the mechanism by which CD154 blockade potently inhibits aspects of innate cell recruitment during transplantation (Ferrer et al, 2012b). While the contribution of CD154-CD11b interactions to the development of alloimmunity remains an unexplored area, the potential role of this interaction will likely enter into the calculus of whether CD154 or CD40-directed reagents are likely to provide more favorable results for immune modulation in the setting of transplantation.…”