Treatment with anti-RANKL antibody reduces infarct size and attenuates dysfunction impacting on neutrophil-mediated injury

Abstract

Selective pharmacological treatments targeting reperfusion injury produced modest protective effects and might be associated with immunosuppression. In order to identify novel and better-tolerated approaches, we focused on the neutralization of receptor activator of nuclear factor kappa-B ligand [RANKL], a cytokine recently shown to activate inflammatory cells (i.e. neutrophils) orchestrating post-infarction injury and repair. Myocardial ischemia (60min) and reperfusion injury was surgically induced in C57Bl/6 mice. In hearts and serum, RANKL was early upregulated during reperfusion. A "one-shot" injection with neutralizing anti-RANKL IgG during ischemia ameliorated myocardial infarct size and function, but not adverse remodeling (determined by Magnetic Resonance Imaging [MRI]) as compared to Vehicle or control IgG. These beneficial effects were accompanied in vivo by reduction in cardiac neutrophil infiltration, reactive oxygen species (ROS) and MMP-9 release. Anti-RANKL IgG treatment suppressed sudden peak of neutrophil granule products in mouse serum early after reperfusion onset. In vitro, RANK mRNA expression was detected in isolated mouse neutrophils. Co-incubation with neutralizing anti-RANKL IgG abrogated RANKL-induced mouse neutrophil degranulation and migration, suggesting a critical role of RANKL in neutrophil-mediated injury. Conversely, anti-RANKL IgG did not affect salvage pathways in cardiac cells (i.e. ERK p42/p44, Akt and STAT-3) or macrophage cardiac infiltration. Finally, treatment with anti-RANKL IgG showed no effect on B and T lymphocyte polarization (in serum, spleen and infarcted myocardium) and circulating chemokines as compared with Vehicle or control IgG. In conclusion, acute treatment with anti-RANKL IgG improved cardiac infarct size and function by potentially impacting on neutrophil-mediated injury and repair.

Therapeutic targeting of neutrophil exocytosis

“…16,91,[146][147][148][149][150] Inhibition of neutrophil recruitment reduces organ injury in many animal models. [151][152][153][154][155][156][157][158] Data suggest that release of granule cargo and ROS generation mediate neutrophil-dependent organ damage. 154,159,160 A role for ROS is supported by finding oxidant-modified proteins in organs damaged by ischemia-reperfusion injury.…”

“…[151][152][153][154][155][156][157][158] Data suggest that release of granule cargo and ROS generation mediate neutrophil-dependent organ damage. 154,159,160 A role for ROS is supported by finding oxidant-modified proteins in organs damaged by ischemia-reperfusion injury. [161][162][163] A role for granule exocytosis is supported by reduction in organ damage following pharmacologic inhibition or genetic deletion of neutrophil granule constituents, including elastase and MMPs.…”

Selective inhibition of receptor activator of NF-κB ligand (RANKL) in hematopoietic cells improves outcome after experimental myocardial infarction

“…Role of RANKL in neutrophil infiltration and MMP-9 secretion was recently demonstrated early after MI [16]. However, in our long-term study, it is more probable that beneficial effects seen after hematopoietic RANKL inhibition are mediated by macrophages which infiltrate ischemic myocardium long term after MI [30].…”

Osteoimmunology: Inflammatory osteolysis and regeneration of the alveolar bone

“…Del‐1‐deficient mice developed spontaneous periodontitis that featured excessive neutrophil infiltration and IL17 expression (Eskan et al., ). Moreover, RANKL can induce neutrophil degranulation and migration, suggesting a critical role of RANKL in neutrophil‐mediated injury (Carbone et al., ). Taken together, living neutrophils protect the barriers from invading microorganisms while apoptotic neutrophils modulate macrophage polarization towards an anti‐inflammatory and resolution phenotype.…”