Sepsis is a potentially life-threatening complication of an infection. Sepsis is mostly the consequence of systemic bacterial infections leading to exacerbated activation of immune cells by bacterial products, resulting in enhanced release of inflammatory mediators. Lipopolysaccharide (LPS), the major component of the outer membrane of Gram-negative bacteria, is a critical factor in the pathogenesis of sepsis, which is sensed by Toll-like receptor 4 (TLR4). The scientific community highly pursues the development of antagonists capable of blocking the cytokine storm by blocking TLR4. We report here that a recombinant molecule of 14.5 kDa belonging to the Fasciola hepatica fatty acid binding protein (Fh15) is capable of significantly suppressing the LPS-induced cytokine storm in a mouse model of septic shock when administered by the intraperitoneal route 1 h after a lethal LPS injection. These results suggest that Fh15 is an excellent candidate for drug development against endotoxemia.

The aim of this study was to identify inflammation‐associated markers during the early phase of sepsis in rhesus macaque. Four rhesus macaques were given an intravenous dose of 1010 CFU/kg of E. coli. Blood samples were collected before, or 30 minutes, 2, 4, 6 and 8 hours after E. coli infusion. Physiological parameters, bacteremia, endotoxemia, C‐reactive protein (CRP), procalcitonin (PCT), and plasma cytokines/chemokines were determined for each animal. Bacteremia was present in all animals from 30 minutes to 3 hours after E. coli infusion whereas endotoxin was detected during the full‐time course. CRP and PCT levels remained at detectable levels during the whole experimental window suggesting an ongoing inflammatory process. Signature cytokines and chemokines such as TNF‐α, MIP‐1α, and MIP‐1β peaked about 2 hours after E. coli infusion and decreased thereafter. Plasma IL‐6, IL‐12p40, IFN‐γ, and IL‐1Ra, as well as I‐TAC, MIG, IP‐10 and MCP‐1, remained at detectable levels after 4 hours of E. coli infusion. This nonhuman primate model could be useful for the assessment of new therapeutics aiming to suppress key inflammatory markers throughout sepsis early phases.

Sepsis caused by Gram-negative bacteria affects 1.7 million adults annually in the United States and is one of the most important causes of death at intensive care units. Although the effective use of antibiotics has resulted in improved prognosis of sepsis, the pathological and deathly effects have been attributed to the persistent inflammatory cascade.

Sepsis is a life-threatening syndrome characterized by metabolic and systemic dysregulation in the presence of an invading pathogen, such as bacteria or fungi. In the initial stages of this syndrome, the body, in an attempt to eradicate the pathogen, secretes high levels of pro-inflammatory cytokines and chemokines that leads to an anti-inflammatory state, which leads to organ dysfunction and death. Despite the efforts to find targeted therapeutics to treat septic patients, physicians rely on the administration of antibiotics and fluids. Hence, the development of novel targeted therapeutics to treat septic patients at early stages of sepsis is highly important to save the lives of these patients. The aim of this study was to identify inflammation markers during the early phase of sepsis in rhesus macaque. Four rhesus macaque were given an intravenous dose of 1010 CFU/kg of E. coli. Blood samples were collected before, 30 minutes, 2, 4, 6 and 8 hours after E. coli infusion. Physiological parameters, bacteremia, endotoxemia, C-reactive protein (CRP), procalcitonin (PCT), and cytokines and chemokines were determined for each animal at each time point. Bacteremia was present in all animals from 30 minutes to 3 hours after E. coli infusion. Endotoxin, CRP and PCT levels remained detectable during the whole experimental window. Signature cytokines and chemokines such as TNFα, MIP1α, and MIP1β peaked about 2 hours after E. coli infusion and decreased thereafter. Plasma IL6, IL12p40, IFNγ, and IL1Ra, ITAC, MIG, IP10 and MCP1, remained at detectable levels after 4 hours of E. coli infusion. This non-human primate model could be useful for the assessment of new therapeutics aiming to suppress key inflammatory markers throughout sepsis early phases.

Sepsis is the leading cause of death from infections. It involves, both pathogen and host factors and it is characterized by an exacerbation of inflammatory cytokines and chemokines and organ dysfunction and failure. Recently, we reported that a recombinant Fasciola hepatica fatty acid binding protein, termed Fh15, is capable of suppressing the LPS induced expression of inflammatory cytokines such as IL‐1β and TNFα in murine bone marrow derived macrophages in vitro. We also demonstrated that such anti‐inflammatory effect is achieved by targeting specifically the CD14 co‐receptor, which results in a complete suppression of TLR4 activation and makes macrophages irresponsive to subsequent LPS‐stimuli. In the current study, we evaluated the capacity of Fh15 to suppress the TLR4‐activation in vitro, as well as its capacity to therapeutically suppress the cytokine storm in a mouse model of septic shock. We also tested the ability of Fh15 to suppress the activation of multiple TLRs in response to Gram‐positive and Gram‐negative whole bacteria extracts in vitro. For in vivo studies, we used female BALB/c mice that received a lethal intraperitoneal (i.p.) injection of LPS‐E. coli and 1h later received a single i.p. injection with 50μg Fh15. Animals were sacrificed 12h after the LPS challenge. For in vitro experiments, we used THP1‐CD14 cells, which were cultured with Fh15 prior to stimulation with optimized concentrations of 1×108 cells of Klebsiella pneumoniae and Enterococcus faecalis. Results demonstrated that, although Fh15 was unable to stimulate the secretion of any inflammatory cytokine, it significantly suppressed the levels of serum IFNγ (p=0.0425), TNFα (p=0.0008), IL‐1β (p=0.0021) in all animals exposed to lethal doses of LPS. Fh15 also significantly suppressed the levels in serum of two macrophage inflammatory proteins MIP‐1α (p=0.0027) and MIP‐1β (p<0.0001), two chemotactic chemokines that play relevant roles in the inflammatory process. Moreover, we also demonstrated that Fh15 inhibits the stimulation of various TLRs in response to whole bacteria extracts, suggesting that Fh15 could have a broad spectrum of action. These results support the possibility of using Fh15 as an excellent alternative for an anti‐inflammatory drug in pre‐clinical studies in the near future.Support or Funding InformationThis study was supported by MBRS‐RISE R25GM061838‐13, and NIH grants G12MD007600 and 2P40OD012217.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.