ABSTRACT
The inflammatory sequelae of ischemia-reperfusion injury (IRI) are a major causal factor of tissue injury in various clinical settings. MicroRNAs (miRs) are short, non-coding RNAs, which regulate protein expression. Here, we investigated the role of miR-155 in IR-related tissue injury. Quantifying microRNA-expression levels in a human muscle tissue after IRI, we found miR-155 expression to be significantly increased and to correlate with the increased expression of TNF-α, IL-1ß, CD105, and Caspase3 as well as with leukocyte infiltration. The direct miR-155 target gene SOCS-1 was downregulated. In a mouse model of myocardial infarction, temporary LAD ligation and reperfusion injury resulted in a smaller area of necrosis in miR-155-/- animals compared to wildtype animals. To investigate the underlying mechanisms, we evaluated the effect of miR-155 on inflammatory cell recruitment by intravital microscopy and on the generation of reactive oxygen species (ROS) of macrophages. Our intravital imaging results demonstrated a decreased recruitment of inflammatory cells in miR-155-/- animals during IRI. The generation of ROS in leukocytic cells of miR-155-/- animals was also reduced. RNA silencing of the direct miR-155 target gene SOCS-1 abrogated this effect. In conclusion, miR-155 aggravates the inflammatory response, leukocyte infiltration and tissue damage in IRI via modulation of SOCS-1-dependent generation of ROS. MiR-155 is thus a potential target for the treatment or prevention of IRI.
Subject(s)
Chemotaxis, Leukocyte/physiology , Inflammation/metabolism , MicroRNAs/metabolism , Reperfusion Injury/metabolism , Transendothelial and Transepithelial Migration/physiology , Animals , Enzyme-Linked Immunosorbent Assay , Fluorescent Antibody Technique , Humans , Inflammation/genetics , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Real-Time Polymerase Chain Reaction , Reperfusion Injury/genetics , Respiratory Burst/physiology , Suppressor of Cytokine Signaling 1 Protein , Suppressor of Cytokine Signaling Proteins/metabolism , TransfectionABSTRACT
INTRODUCTION: The aim of the presented study was to investigate nerve regeneration after application of C3-Toxin, a Rho-GTPase inhibitor and to correlate morphometry, neurophysiology, and function in an end-to-side peroneal/tibial nerve repair model of the rat. MATERIALS AND METHODS: Twenty rats with a peroneal to tibial end-to-side neurorrhaphy were divided into two groups: 1) control group, 2) C3 fusion toxin group with intrafascicular application of 1 µg/100 µl C3 fusion toxin. Survival time was 8 weeks. Nerve conduction velocities and motor function were analyzed and histomorphological evaluation consisting of measurement of intraneural collagen level, axon count, total nerve area, myelination index, and N-ratio followed. RESULTS: Evaluation of motor function and nerve conduction did not show any statistical differences. Histological analysis revealed higher axon count, thicker myelin sheaths, and higher myelination index in the C3 fusion toxin group (P < 0.001). Comparison of N-ratio and intraneural collagen level were without statistical significance. CONCLUSION: The current study shows that application of C3 fusion toxin leads to higher myelination and increases axonal sprouting.