Blood cells serve as a source of factor‐inducing rapid ischemic tolerance in brain

Abstract

Ischemic tolerance (IT) has gained attention as an attractive strategy for improving stroke outcome. Recently, it was shown that signal responsible for rapid IT induction (tolerance induction factor - TIF) is transmitted via circulating blood. In this study, we have hypothesized about the role of the blood cell compartment in TIF production. We used hind-limb ischemia to generate TIF as a rapid preconditioning against transient middle cerebral artery occlusion (MCAO). The essential properties of protein synthesis inhibitors actinomycin D and cycloheximide were utilized to obtain the following results: (i) TIF is proteinaceous. Hind-limb ischemia mediates gene expression followed by translation, resulting in the production of TIF. Blocking of each of these two steps in protein synthesis resulted in rapid infarct evolution (281.5 ± 23.37 and 330.4 ± 71.8 mm , respectively). (ii) Tourniquet-treated muscle is not a source of TIF. Actinomicine D injected into rat prior to tolerance induction significantly suppressed RNA synthesis in blood cells and muscle tissue. Cross-circulation of those rats (donors) with control animals (recipients) did not mediate significant infarct reduction (272.9 ± 12.45 mm ), even when hind-limb ischemia was performed before MCAO in the recipient (223.2 ± 37.51 mm ). (iii) Blood cells serve as a source of TIF. Preischemic transfusion of plasma-free, protein-synthesis-inactive blood cells, which were obtained from tolerant animals did not reduce infarct volume in recipients (131 ± 16.1 mm ) in a range comparable with their protein-synthesis-active counterparts (17.2 ± 12 mm ). We can conclude that blood cells are associated with the induction of rapid IT via production of a bioactive proteinaceous substance.

Rapid remote conditioning mediates modulation of blood cell paracrine activity and leads to the production of a secretome with neuroprotective features

“…Our previous findings indicate that the preserved protein synthesis (i.e . transcription and translation) in stimulated blood cells plays an essential role in neuroprotection against stroke (Bonova et al ). The implementation of the bioinformatic‐based analysis in the present experiments allowed us to identify actively secreted proteins that were extracellularly released because of stimulation.…”

“…Additionally, the potential of peripheral blood cells for tissue protection and repair has recently been proven. In our previous work, we demonstrated that a mixture of all peripheral blood cells can promote brain tissue protection after stimulation (Bonova and Gottlieb ; Bonova et al ). However, the main cellular component of blood, that is, erythrocytes, discard their nuclei during maturation and are thought to be unable to synthesise proteins.…”

Identification of Proteins Responsible for the Neuroprotective Effect of the Secretome Derived from Blood Cells of Remote Ischaemic Conditioned Rats

“…There is ample evidence that RIC-mediated neuroprotection could be transferred indirectly via blood transfusion [ 4 , 5 ] or the blood cell-derived secretome drawn from RIC-stimulated animals [ 6 ]. In our recent work, we discovered that protein synthesis is crucial for the induction of tolerant phenotype in ischaemia-affected animals.…”