655 - NLRP3 Inflammasome-deficient Neonatal Mice Treated with Antibiotics may be Protected from Escherichia coli Sepsis-induced Acute Cerebral Inflammation
Saturday, April 29, 2023
3:30 PM – 6:00 PM ET
Poster Number: 655 Publication Number: 655.24
Esther M. Speer, Stony Brook Children's Hospital, Stony Brook, NY, United States; Amrendra Singh, Stony Brook Children's Hospital, Port Jefferson, NY, United States; Atilade Adedayo. Adedeji, Stony Brook University, Stony Brook, NY, United States
Associate Professor of Pediatrics Stony Brook Children's Hospital Stony Brook, New York, United States
Background: Neonatal sepsis triggers intense inflammatory responses involving inflammasome activation that contribute to mortality and brain injury, for which no effective therapy exists. The phosphodiesterase inhibitor pentoxifylline (PTX) is a candidate anti-inflammatory agent for newborn sepsis, however has limited inflammasome-suppressive properties. The effects of combined NLRP3 inflammasome suppression and PTX on cerebral inflammation in neonatal sepsis are unknown. Objective: To determine the effects of NLRP3 inflammasome-deficiency (NLRP3-/-) on Escherichia coli-induced cerebral cytokine and chemokine concentrations in newborn mice in the presence or absence of gentamicin (GENT) or combined GENT and PTX (GENT+PTX). Design/Methods: Newborn (< 24 hours (h) old) NLRP3-/- mice (B6.129S6-Nlrp3tm1Bhk/J; Jackson Laboratory, n=65) were injected intraperitoneally with live Escherichia coli K1 (105 colony forming units (CFU)/g weight) or an equal volume of saline for controls. After 1.5 hours (h), septic pups were randomly assigned to saline, GENT, or GENT+PTX, whereas controls received saline. Pups were euthanized after an additional 4 h, and CFUs, cytokines and chemokines were measured in homogenized brain tissue with multiplex immunoassays, and compared with 1-way ANOVA and Kruskal-Wallis tests. Results: Cerebral IL-1ß, TNF and IL-10 but not IL-6 were significantly lower in untreated E. coli-septic neonatal NLRP3-/- mice compared to our previous findings in wild-type C57BL/6J mice (Speer et al., Front Immunol 2020). Compared to controls, E. coli-septic untreated NLRP3-/- mice showed significantly higher cerebral IL-6, G-CSF, keratinocyte-derived chemokine (CXCL1), chemokine ligand 2 (CCL2), and CCL4 (p< 0.01), whereas TNF, IL-1ß, IL-12, and IL-10 did not increase. Addition of GENT and GENT+PTX suppressed E. coli-induced cerebral expression of IL-6, G-CSF, CXCL1, CCL2, CCL3, and CCL4 (p< 0.01) (Fig. 1). GENT+PTX diminished IL-17 compared to GENT alone (p< 0.05), however did not further decrease any other cytokines and chemokines. Cerebral tissue CFUs remained low in untreated and antibiotic-treated septic mice, and addition of PTX did not augment bacterial growth.
Conclusion(s): NLRP3-/- reduces sepsis-induced acute cerebral cytokines, which can be further diminished with antibiotic therapy, whereas addition of PTX provides only limited anti-inflammation. The NLRP3 inflammasome may be a promising future target to protect the neonatal brain from sepsis-induced inflammatory injury.
