Serum active Granzyme A: a new biomarker that contributes to the pathogenesis of peritoneal sepsis

of the work presented at the 30th ECCMID 2020, European Congress of Clinical Microbiology and Infectious Diseases, organized by the European Society of Clinical Microbiology and Infectious Diseases (ESCMID).-- www.eccmid.org .-- www.escmid.org.-- Accepted abstract 1508.
[Background] Peritonitis is one of the most common leading cause of sepsis. Recent evidence suggests that Granzyme A (GzmA), a serine protease mainly expressed in NK cells and T cells, could act as a proinflammatory mediator and could play an important role in the pathogenesis of sepsis. This work aims to analyze the role of serum GzmA as a biomarker and therapeutic target in peritoneal sepsis.
[Materials/methods] Concentration and enzyme activity of soluble GzmA were sequentially analyzed in serum from healthy donors and patients with peritonitis and were correlated with the Sequential Organ Failure Assessment (SOFA) score. Peritonitis was induced in C57Bl/6 (Wt) and GzmA-KO mice by cecal ligation and puncture (CLP). Mice were treated intraperitoneally with antibiotics and with serpinb6b, a specific GzmA inhibitor, for 5 days. Mouse survival was monitored during 14 days and the levels of serum proinflammatory cytokines and bacterial load in blood and spleen were analyzed at 6 and 24h from CLP.
[Results] We have found high levels of GzmA in serum of patient with peritonitis. Most importantly, we observed that GzmA activity in serum correlates with SOFA score, suggesting that active GzmA could play an important role in sepsis development in peritonitis patients and could be a new biomarker of sepsis severity. In order to analyze the therapeutical potential of soluble GzmA in peritoneal sepsis, we used the CLP mouse model. After peritonitis induction, GzmA-KO mice exhibit increased survival compared with Wt mice, which correlated with reduced levels of proinflammatory cytokines in serum. The analysis of bacterial load in blood and spleen showed no differences between Wt and GzmA-KO mice suggesting that GzmA does not play an important role in bacterial control. Treatment with serpinb6b reduced mortality, which correlated with reduced cytokine serum levels in serum, confirming the therapeutical potential of gzmA to treat peritoneal sepsis.
[Conclusions] Our findings confirm that soluble GzmA plays an important role in the pathogenesis of sepsis and could be a new therapeutic target and a biomarker for the treatment of peritoneal sepsis.