Open AccessDifferential effector responses by circulating/blood and tissue/peritoneal neutrophils following burn combined with E nterococcus faecalis infection
Author(s) -
Fazal Nadeem,
Shelip Alla,
Siddiqui Erum,
Ali Ashraf,
Azim Anser C.,
AlGhoul Walid M.
Publication year - 2012
Publication title -
fems immunology & medical microbiology
Language(s) - English
Resource type - Journals
eISSN - 1574-695X
pISSN - 0928-8244
DOI - 10.1111/j.1574-695x.2011.00881.x
Subject(s) - biology , microbiology and biotechnology , neutrophil extracellular traps , immunology , cd18 , intracellular , respiratory burst , enterococcus faecalis , granulocyte , extracellular , elastase , flow cytometry , integrin alpha m , inflammation , staphylococcus aureus , bacteria , biochemistry , genetics , enzyme
Recently we found that superimposition of E nterococcus faecalis infection on burn injury caused an eruption of host mortality not seen with either individual challenge. We hypothesized that the Enterococcus bacteria, and/or factors related to these organisms, aggravate burn‐induced modulations in host defense by neutrophils. Our study focuses on alterations in neutrophils’ oxidative, proteolytic, and adhesive functions and transendothelial migration of neutrophils in burn rats inoculated with E. faecalis . Rats were subjected to burn (30% total body surface area) and then intra‐abdominally inoculated with E. faecalis (10 4 CFU kg −1 b.w). Polymorphonuclear neutrophils ( PMN s) were harvested from circulating/blood and tissue/peritoneal cavity at day‐2 post injury. Extracellular release ofO 2−anion production was determined by luminometry, and intracellular production of reactive oxygen species was measured by digital imaging technique. Fluoroscan analysis and confocal microscopy determined intracellular elastase production. The expression of adhesion molecule CD 11b/ CD 18 was performed by flow cytometry. Calcein AM ‐labeled PMN s were co‐cultured with TNF ‐α‐stimulated rat lung microvascular endothelial cells, and their ability to adhere was assessed by fluorometry and digital imaging and finally, chemotaxis was measured by neutrophil transmigration assays. The results showed differential effector responses by circulatory and/or tissue PMN s. Tissue/peritoneal PMN s produced moreO 2−, less intracellular elastase, and increased expression of CD 11b/ CD 18 accompanied with increased adhesivity of MIP ‐2‐stimulated PMN s to endothelial cells as compared to circulatory/blood PMN s. This differential effect was more pronounced following burn plus E . faecalis infection, indicating that the combined injury changed neutrophil functions.