Toll-like receptor 4 stimulation before or after Streptococcus pneumoniae induced sepsis improves survival and is dependent on T-cells.

INTRODUCTION: Endotoxin tolerance improves outcomes from gram negative sepsis but the underlying mechanism is not known. We determined if endotoxin tolerance before or after pneumococcal sepsis improved survival and the role of lymphocytes in this protection. METHODS: Mice received lipopolysaccharide (LPS) or vehicle before or after a lethal dose of Streptococcus pneumoniae. Survival, quantitative bacteriology, liver function, and cytokine concentrations were measured. We confirmed the necessity of Toll-like receptor 4 (TLR4) for endotoxin tolerance using C3H/HeN (TLR4 replete) and C3H/HeJ (TLR4 deficient) mice. The role of complement was investigated through A/J mice deficient in C5 complement. CBA/CaHN-Btk(xid/)/J mice with dysfunctional B cells and Rag-1 knockout (KO) mice deficient in T and B cells delineated the role of lymphocytes. RESULTS: Endotoxin tolerance improved survival from pneumococcal sepsis in mice with TLR4 that received LPS pretreatment or posttreatment. Survival was associated with reduced bacterial burden and serum cytokine concentrations. Death was associated with abnormal liver function and blood glucose concentrations. Endotoxin tolerance improved survival in A/J and CBA/CaHN-Btk(xid/)/J mice but not Rag-1 KO mice. CONCLUSIONS: TLR4 stimulation before or after S. pneumoniae infection improved survival and was dependent on T-cells but did not require an intact complement cascade or functional B cells.

An A2A adenosine receptor agonist, ATL313, reduces inflammation and improves survival in murine sepsis models.

BACKGROUND: The pathophysiology of sepsis is due in part to early systemic inflammation. Here we describe molecular and cellular responses, as well as survival, in A 2A adenosine receptor (AR) agonist treated and untreated animals during experimental sepsis. METHODS: Sepsis was induced in mice by intraperitoneal inoculation of live bacteria (Escherichia coli or Staphylococcus aureus) or lipopolysaccharide (LPS). Mice inoculated with live bacteria were treated with an A 2A AR agonist (ATL313) or phosphate buffered saline (PBS), with or without the addition of a dose of ceftriaxone. LPS inoculated mice were treated with ATL313 or PBS. Serum cytokines and chemokines were measured sequentially at 1, 2, 4, 8, and 24 hours after LPS was administered. In survival studies, mice were followed until death or for 7 days. RESULTS: There was a significant survival benefit in mice infected with live E. coli (100% vs. 20%, p = 0.013) or S. aureus (60% vs. 20%, p = 0.02) when treated with ATL313 in conjunction with an antibiotic versus antibiotic alone. ATL313 also improved survival from endotoxic shock when compared to PBS treatment (90% vs. 40%, p = 0.005). The serum concentrations of TNF-alpha, MIP-1 alpha, MCP-1, IFN-gamma, and IL-17 were decreased by ATL313 after LPS injection (p < 0.05). Additionally, ATL313 increased the concentration of IL-10 under the same conditions (p < 0.05). Circulating white blood cell concentrations were higher in ATL313 treated animals (p < 0.01). CONCLUSION: Further studies are warranted to determine the clinical utility of ATL313 as a novel treatment for sepsis.

Eukaryotic translation initiation factor 5A small interference RNA-liposome complexes reduce inflammation and increase survival in murine models of severe sepsis and acute lung injury.

BACKGROUND: Many novel therapeutics have failed to reduce all-cause mortality associated with severe sepsis. Eukaryotic translation initiation factor 5A (eIF5A) is a regulator of apoptosis as well as inflammatory cell activation, making it a potential target for sepsis therapy. METHODS: In a murine model of severe sepsis, mice were intraperitoneally challenged with lipopolysaccharide (LPS). Mice were treated both before and after LPS challenge with liposome complexes containing either an eIF5A-specific or control small interference RNA (siRNA), and both survival and serum concentrations of inflammatory cytokines were monitored. The ability of eIF5A siRNA to reduce inflammatory cytokines was also tested in a model of acute lung injury established by intranasal administration of LPS to mice. RESULTS: There was a statistically significant increase in the rate of survival for mice intraperitoneally challenged with LPS that received eIF5A siRNA, compared with that noted for mice that received control siRNA (71% vs. 5%; P< .001), as well as a reduction in cytokine expression in serum. Concentrations of proinflammatory cytokines were also reduced in the lung homogenates and serum of mice that were intranasally challenged with LPS and received eIF5A siRNA (P< or = .05). CONCLUSIONS: eIF5A siRNA-liposome complexes reduced inflammation and contributed to increased survival in a model of severe sepsis, decreased inflammation in a model of acute lung injury, and should be considered for clinical use.

A new method for measuring blood-brain barrier permeability demonstrated with Europium-bound albumin during experimental lipopolysaccharide (LPS) induced meningitis in the rat.

The blood-brain barrier (BBB) is a critical extrameningeal site of injury during bacterial meningitis, manifested by enhanced BBB permeability (BBBP). Previous methods to measure altered BBBP during meningitis involve radioactive materials, or are poorly quantified. Europium (EU) is a fluorescent, non-radioactive metal that is a sensitive and stable marker. Europium fluorescence can be measured with a spectrophotometer capable of time-resolved fluorescence (TRF). We used EU-albumin (EU-A) to examine BBBP in experimental lipopolysaccharide (LPS) induced meningitis. The results presented here introduce a simple and accurate method for measuring BBB permeability.