engleski

Granulysin - mediated cytotoxicity in the peripheral blood of patients with non-ST segment elevation myocardial infarction.

Introduction: GNLY is a member of the family of saposin-like lipid binding proteins with pro- apoptotic features that is expressed in activated T, NK, and NKT cells. The function of the constitutively secreted 15-kDa precursor form of GNLY is poorly understood, whereas mature GNLY form (9 kDa) shares the exocytose pathway with perforin. Rapid influx of GNLY into cells through perforin pores or GNLY binding to the target cell membrane induce caspase-independent and a caspase-dependent apoptosis of target cells. The multiple pathways used by GNLY to enter target cells are indicative of its broad cytotoxic and inflammatory activity. The aim of our study was to investigate granulysin (GNLY)-mediated cytotoxicity in the peripheral blood of patients with non-ST segment elevation myocardial infarction (NSTEMI) treated with medicament therapy. Material and methods: Thirty-four NSTEMI patients with a median age of 69 years, and 25 age-matched healthy subjects were enrolled in the study. Double labeling by immunohistology was used to analyze the presence of GNLY+CD3+, GNLY+CD56+ NK cells and IL-15 in myocardial paraffin-embedded tissue sections from persons who died in the first or in the fifth week after NSTEMI and from patients who died from non-cardiac causes. Frequency of GLNY+ cells in lymphocyte subpopulations and NK cell-mediated apoptosis of K-562 cells were analyzed by three color flow cytometry or NK cell-mediated apoptosis assay, respectively. Results: It was shown that on day 7 after NSTEMI, the number of GNLY+ lymphocytes in the peripheral blood increased approximately 6 fold of that in the healthy subjects. On day 14, the number of GNLY+ cells significantly decreased in T, NKT, and both CD56+dim and CD56+bright NK subsets. The presence of GNLY+CD3+ and GNLY+CD56+ NK cells in myocardial tissue of persons who died in the first week after STEMI implies their role in tissue recruitment, probably due to the augment in interleukin-15 expression in peri-necrotic cardiomyocytes. By day 28, the percentage of GNLY+ lymphocytes in peripheral blood returned to the levels similar to that of the healthy subjects. Anti-GNLY mAb decreased NK cell mediated apoptosis of K562 targets from days 1 after STEMI, whereas both anti-GNLY and anti- perforin mAbs were required to significantly decrease apoptosis in assays using cells from days 7, 21 and 28. On day 14, K562 apoptosis was nearly absent. Conclusion: It seems that in NSTEMI patients treated with anti-ischemic drugs, GNLY+ lymphocytes with apoptotic properties recruited in ischemic myocardium probably attracted by IL-15.

granulysin ; interleukin 15 ; myocardial infarction ; NK cell ; T cell

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