Fibrinogen is increased in the spleen over the course of murine endotoxemia

Abstract

Abstract The fibrinogen protein is composed of three subunits encoded for by the genes Fga, Fgb, and Fgg. This trimer is a main component of blood clots. Irregular blood clotting contributes to low blood pressure during septic shock, which eventually leads to death from total system organ failure. A previously published data set finds Fga, Fgb, and Fgg to be dysregulated during sepsis in the serum of both wildtype (WT) and toll-like receptor 4 (TLR4) deficient mice. Deficiency in the innate immune receptor TLR4 models immune ataxia that occurs in patients who recover from septic shock, surviving patients have an increased risk of mortality due to secondary infection. We hypothesize that fibrinogen contributes to symptoms of septic shock independent of the TLR4 pathway. In this study we confirm that fibrinogen is transcriptionally upregulated in the liver of both WT and TLR4−/− mice over the course of LPS induced endotoxemia. Western blots were completed using organ lysates from liver, spleen, kidney, and brain of WT and TLR4−/− mice from 0, 6, 12, and 18 hours after induction of endotoxemia with intraperitoneal injection of 30 mg/kg lipopolysaccharide (LPS). Western blots show that WT and TLR4−/− control mice express similar amounts of fibrinogen in organs, and that there is more fibrinogen in the liver than the spleen, which is consistent with current literature. Western blots conducted with endotoxemic samples show that over the course of disease in WT mice, fibrinogen levels are consistent in the liver but increase in the spleen. Continued experiments in TLR4−/− mice will determine the level of TLR4-independent fibrinogen activation during sepsis and provide evidence for use of serum clotting modulators in patients who have recovered from septic shock. This study is supported by a Towson University FDRC grant awarded to EMH, a Fisher College of Science and Mathematics undergraduate research award to KEN, and the 2022 Linda Sweeting Summer research fellowship awarded to KEN by the Towson University Department of Chemistry.