Érythropoïétine et neuroprotection

Traumatic Optic Neuropathy: Update on Management

Traumatic optic neuropathy is one of the causes of visual loss caused by blunt or penetrating head trauma and is classified as both direct and indirect. Clinical history and examination findings usually allow for the diagnosis of traumatic optic neuropathy. There is still controversy surrounding the management of traumatic optic neuropathy; some physicians advocate observation alone, while others recommend steroid therapy, surgery, or both. In this entry, we tried to highlight traumatic optic neuropathy's main pathophysiologic mechanisms with the most available updated treatment. Recent research suggests future therapies that may be helpful in traumatic optic neuropathy cases.

Whether erythropoietin can be a neuroprotective agent against premature brain injury: cellular mechanisms and clinical efficacy

Preterm infants are at high risk of brain injury. With more understanding of the preterm brain injury's pathogenesis, neuroscientists are looking for more effective methods to prevent and treat it, among which erythropoietin (Epo) is considered as a prime candidate. This review tries to clarify the possible mechanisms of Epo in preterm neuroprotection and summarize updated evidence considering Epo as a pharmacological neuroprotective strategy in animal models and clinical trials. To date, various animal models have validated that Epo is an anti-apoptotic, anti-inflammatory, anti-oxidant, anti-excitotoxic, neurogenetic, erythropoietic, angiogenetic, and neurotrophic agent, thus preventing preterm brain injury. However, although the scientific rationale and preclinical data for Epo's neuroprotective effect are promising, when translated to bedside, the results vary in different studies, especially in its long-term efficacy. Based on existing evidence, it is still too early to recommend Epo as the standard treatment for preterm brain injury.

Erythropoietin, a multifaceted protein with innate and adaptive immune modulatory activity

Erythropoietin (EPO) is a glycoprotein produced mainly by the adult kidney in response to hypoxia and is the crucial regulator of red blood cell production. EPO receptors (EPORs), however, are not confined to erythroid cells, but are expressed by many organs including the heart, brain, retina, pancreas, and kidney, where they mediate EPO-induced, erythropoiesis-independent, tissue-protective effects. Some of these tissues also produce and locally release small amounts of EPO in response to organ injury as a mechanism of self-repair. Growing evidence shows that EPO possesses also important immune-modulating effects. Monocytes can produce EPO, and autocrine EPO/EPOR signaling in these cells is crucial in maintaining immunologic self-tolerance. New data in mice and humans also indicate that EPO has a direct inhibitory effect on effector/memory T cells, while it promotes formation of regulatory T cells. This review examines the nonerythropoietic effects of EPO, with a special emphasis on its modulating activity on innate immune cells and T cells and on how it affects transplant outcomes.

Nasal administration of the neuroprotective candidate NeuroEPO to healthy volunteers: a randomized, parallel, open-label safety study

BACKGROUND

Delivery of therapeutic agents as erythropoietin (EPO) into Central Nervous System through intranasal route could benefit patients with neurological disorders. A new nasal formulation containing a non-hematopoietic recombinant EPO (NeuroEPO) has shown neuroprotective actions in preclinical models. In the current study, the safety of NeuroEPO was evaluated for the first time in humans.

METHODS

A phase I, randomized, parallel, open-label study was carried out in healthy volunteers. They received, intranasally, 1 mg of NeuroEPO every 8 h during 4 days (Group A) or 0.5 mg of NeuroEPO (Group B) with the same schedule. The working hypothesis was that intranasal NeuroEPO produce <10% of severe adverse reactions in the evaluated groups. Therefore, a rigorous assessment of possible adverse events was carried out, which included tolerance of the nasal mucosa and the effect on hematopoietic activity. Clinical safety evaluation was daily during treatment and laboratory tests were done before and on days 5 and 14 after starting treatment.

RESULTS

Twenty-five volunteers, 56% women, with a mean age of 27 yrs. were included. Twelve of them received the highest NeuroEPO dose. Twenty types of adverse events occurred, with headache (20%) and increase of hepatic enzymes (20%) as the most reported ones. Nasopharyngeal itching was the most common local event but only observed in four patients (16%), all of them from the lowest dose group. About half of the events were very probably or probably caused by the studied product. Most of the events were mild (95.5%), did not require treatment (88.6%) and were completely resolved (81.8%). No severe adverse events were reported. During the study the hematopoietic variables were kept within reference values.

CONCLUSIONS

NeuroEPO was a safe product, well tolerated at the nasal mucosa level and did not stimulate erythropoiesis in healthy volunteers.

TRIAL REGISTRATION

Cuban Public Registry of Clinical Trials RPCEC00000157 , June 10, 2013.

Neuroprotective properties of mitochondria-targeted antioxidants of the SkQ-type

In 2008, using a model of compression brain ischemia, we presented the first evidence that mitochondria-targeted antioxidants of the SkQ family, i.e. SkQR1 [10-(6′-plastoquinonyl)decylrhodamine], have a neuroprotective action. It was shown that intraperitoneal injections of SkQR1 (0.5–1 μmol/kg) 1 day before ischemia significantly decreased the damaged brain area. Later, we studied in more detail the anti-ischemic action of this antioxidant in a model of experimental focal ischemia provoked by unilateral intravascular occlusion of the middle cerebral artery. The neuroprotective action of SkQ family compounds (SkQR1, SkQ1, SkQTR1, SkQT1) was manifested through the decrease in trauma-induced neurological deficit in animals and prevention of amyloid-β-induced impairment of long-term potentiation in rat hippocampal slices. At present, most neurophysiologists suppose that long-term potentiation underlies cellular mechanisms of memory and learning. They consider inhibition of this process by amyloid-β1-42as anin vitromodel of memory disturbance in Alzheimer’s disease. Further development of the above studies revealed that mitochondria-targeted antioxidants could retard accumulation of hyperphosphorylated τ-protein, as well as amyloid-β1-42, and its precursor APP in the brain, which are involved in developing neurodegenerative processes in Alzheimer’s disease.

Erythropoietin upregulates growth associated protein-43 expression and promotes retinal ganglion cell axonal regeneration in vivo after optic nerve crush

In this study, we established a rat model of optic nerve crush to explore the effects of erythropoietin on retinal ganglion cell axonal regeneration. At 15 days after injury in erythropoietin treated rats, retinal ganglion cell densities in regions corresponding to the 1/6, 3/6 and 5/6 ratios of the retinal radius were significantly increased. In addition, the number of growth associated protein-43 positive axons was significantly increased at different distances (50, 250 and 500 μm) from the crush site after erythropoietin treatment. Erythropoietin significantly increased growth associated protein-43 protein levels in the retina after crush injury, as determined by western blot and immunofluorescence analysis. These results demonstrate that erythropoietin protects injured retinal ganglion cells and promotes axonal regeneration.

Perinatal stroke: a case-based review

Neonatal stroke is a diverse clinical entity. Terminology and aetiology described in the literature are very varied. While numerous risk factors are cited, only few case-control studies have investigated them in a systematic fashion. This equipoise extends to the investigational and management profile of perinatal stroke too. Controversy persists about the suitability of detailed haematological thrombophilia workup in the neonatal period. This case-based review details the variable clinical presentation in term and preterm neonates, discusses the current literature, ascertains the respective roles of various imaging modalities, explores relevant new neuroprotective interventions and proposes a systematic approach to clinical and neuroimaging workup. Long-term follow-up is important as many infants suffer neuro-disability, which might need early intervention strategies.