engleski

Biochemical and biological Characterization of Granzyme K and its biological role in systemic inflammation/sepsis

Granzyme K (GrK) is a member of a highly conserved group of potent serine proteases, specifically found in the secretory granules of cytotoxic T lymphocytes and natural killer cells. Based on the report indicating that Inter-alpha inhibitor proteins (IaIp) are the major physiological inhibitors of GrK and on previous findings that showed a significant decrease in plasma IaIp levels in patients with sepsis, it was our aim to determine whether increased levels of uninhibited GrK would contribute to the development of sepsis. To test this hypothesis, a novel competitive GrK-ELISA system was developed ; and the levels of GrK were measured in plasma samples obtained from healthy controls and two sets of patients with sepsis: patients admitted to the emergency department with a putative diagnosis of sepsis and patients with severe sepsis enrolled in a clinical trial. In addition, the molecular form(s) of GrK present in these samples was analyzed by Western blot. The levels of GrK were significantly increased in emergency department patients compared with healthy controls and significantly decreased in patients with severe sepsis enrolled in a clinical trial compared with healthy controls. GrK molecule was detected as a part of high molecular weight complexes of >250 and >150 kDa in healthy controls. In septic patients, GrK was detected as a variety of lower molecular weight complexes. Decrease in complex size correlated with the appearance of a band at 26 kDa similar to the size of free GrK. These results indicate that plasma levels of GrK could serve as a useful diagnostic marker to stage sepsis, permitting better classification of septic patients enabling targeting of specific treatments, and may play a functional role in the development of sepsis. Aside, biochemical and biological characterization of native human GrK was initiated in order to elucidate biological function(s) of this potent serine protease in inflammatory responses/sepsis.

Biomarkers; Inter-alpha inhibitor proteins; Granzymes; Granzyme K; Sepsis; Serine Protease

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