Azithromycin Affords Neuroprotection in Rat Undergone Transient Focal Cerebral Ischemia.

Diana Amantea,Rosaria Greco,Maria Tiziana Corasaniti,Francesco Petrelli,Paolo Tonin,Cristina Tassorelli,Giacinto Bagetta

doi:10.3389/fnins.2019.01256

Abstract

Repurposing existing drugs represents a promising approach for successful development of acute stroke therapies. In this context, the macrolide antibiotic azithromycin has been shown to exert neuroprotection in mice due to its immunomodulatory properties. Here, we have demonstrated that acute administration of a single dose of azithromycin upon reperfusion produces a dose-dependent (ED50 = 1.40 mg/kg; 95% CI = 0.48–4.03) reduction of ischemic brain damage measured 22 h after transient (2 h) middle cerebral artery occlusion (MCAo) in adult male rats. Neuroprotection by azithromycin (150 mg/kg, i.p., upon reperfusion) was associated with a significant elevation of signal transducer and activator of transcription 3 (STAT3) phosphorylation in astrocytes and neurons of the peri-ischemic motor cortex as detected after 2 and 22 h of reperfusion. By contrast, in the core region of the striatum, drug administration resulted in a dramatic elevation of STAT3 phosphorylation only after 22 h of reperfusion, being the signal mainly ascribed to infiltrating leukocytes displaying an M2 phenotype. These early molecular events were associated with a long-lasting neuroprotection, since a single dose of azithromycin reduced brain infarct damage and neurological deficit measured up to 7 days of reperfusion. These data, together with the evidence that azithromycin was effective in a clinically relevant time-window (i.e., when administered after 4.5 h of MCAo), provide robust preclinical evidence to support the importance of developing azithromycin as an effective acute therapy for ischemic stroke.

Highlights

Repurposing existing drugs for novel applications represents a promising strategy for the identification of effective therapies, especially in those clinical settings, such as ischemic stroke, where traditional drug discovery approaches have led to disappointing results (Ginsberg, 2008; Grupke et al, 2015)
In agreement with our previous observation in mice (Amantea et al, 2016b), the neuroprotective effects of azithromycin were not associated with blood flow modifications, since the reduction of CBF induced by middle cerebral artery occlusion (MCAo) and the re-establishment of cerebral perfusion after intraluminal filament withdrawal were not influenced by drug administration
To mice, neuroprotection by azithromycin was associated with elevation of the M2 markers arginase 1 and Ym1, both in the cortex and in the striatum, being in the latter area the Ym1 signal abundant in CD11b immunopositive cells, likely resembling monocytes and neutrophils infiltrating from blood vessels (Figure 1D)

Summary

Introduction

Repurposing existing drugs for novel applications represents a promising strategy for the identification of effective therapies, especially in those clinical settings, such as ischemic stroke, where traditional drug discovery approaches have led to disappointing results (Ginsberg, 2008; Grupke et al, 2015). Due the pivotal role of the immune system in the complex cascade of events that contributes to the progression of ischemic brain injury, a number of preclinical studies have investigated the neuroprotective properties of drugs marketed for Neuroprotection by Azithromycin in Rat MCAo diverse indications, sharing relevant immunomodulatory properties (Amantea and Bagetta, 2016). In this context, the semisynthetic macrolide antibiotic azithromycin (9-deoxy-9aaza-9a-methyl-9a-homoerythromycin A), approved worldwide for the treatment of various community-acquired infections, displays robust immunomodulatory and anti-inflammatory effects in chronic inflammatory airway diseases (Parnham et al, 2014; Cramer et al, 2017). We aimed at characterizing the dose-response and therapeutic window for the neuroprotective effects of azithromycin in adult rat, using a single-dose acute administration, in order to validate the treatment schedule that would be feasible and could be implemented in stroke clinical trials

Methods

Results

Conclusion