Irisin — the future of ischemic stroke therapy?

Irisin is a recently discovered hormone, synthesized mainly by the muscles. Expression of irisin and its precursor named FNDC5 was also found in the heart, kidneys, liver, pancreas, adipose tissue, and brain including cortical neurons, hippocampus, cerebellum, hypothalamus, and spinal cord. The purpose of this study is to review the latest research on the properties of the irisin and its cytoprotective effect against neuronal damage and to draw attention to its possible clinical use in the treatment of stroke. Notch pathway activity increases after ischemic damage, stimulating the repair of the affected brain area. Irisin activates the Notch pathway which inhibits the activity of microglia, secretion of inflammatory factors, and finally leads to reduction of the brain edema. Studies revealed that irisin increases levels of brain-derived neurotrophic factor (BDNF), leading to enhancement of survival and migration of the neurons, and protecting nerve cells from damage during the ischemic stroke. It was also found that irisin maintains mitochondrial integrity, reduces oxidative stress, and exerts a protective effect on the blood-brain barrier. Irisin entails a neuroprotective effect, reducing the extent of the infarcted area and the degree of brain damage. Stimulation of the irisin expression by physical activity or its exogenous administration remains the subject of research that raises hope for development of the new therapeutic options for diseases, especially ischemic stroke.