Cecal inoculum peritonitis: An alternative model for sepsis vascular dysfunction study

Spleen data: Cerium oxide nanoparticles attenuate polymicrobial sepsis induced spenic damage in male Sprague Dawley rats

Sepsis is a serious life threatening medical emergency which, if not treated properly, oftentimes results in organ failure and death. Current sepsis treatment protocols are largely centered on the use of antibiotics and supportive care. Recent studies have suggested that antibiotics fail to be effective for sepsis treatment when administered during hypo-dynamic phase of sepsis that is usually characterized by the presence of a cytokine storm. As such, there is an urgent need to develop novel therapeutic drugs that target the inflammatory cytokines that are secreted as a result of increased reactive oxygen species. Cerium oxide nanoparticles (CeO₂) have been shown to act as anti-inflammatory and anti-oxidant agent. More recently, they have been shown to attenuate polymicrobial insult-induced mortality in Sprague Dawley rats. Here, we investigated whether CeO₂ nanoparticles can attenuate splenic damage in this animal model of sepsis. A single intravenous dose (0.5 mg/kg) of CeO₂ nanoparticles attenuated the sepsis-induced loss in splenic cell structural integrity. These improvements in splenic structure were accompanied by a decrease in expression of late phase pro-inflammatory cytokine high mobility group box 1 (HMGB1) along with reduced bacterial load in the blood and peritoneal fluid of septic animals. Taken together these findings suggest that CeO₂ nanoparticles can be used to attenuate polymicrobial insult-induced splenic damage in Sprague dawley rats.

Circulating leucocytes perpetuate stroke-induced aortic dysfunction

NEW FINDINGS

What is the central question of this study? Does a stroke event influence aortic endothelial function; and what is the role of peripheral circulating leucocytes in stroke on the vascular reactivity of the aorta? What is the main finding and its importance? In vitro co-culture experiments demonstrated that aortic endothelium-dependent relaxation was impaired when rat aortic rings were co-cultured with leucocytes stimulated with serum from stroke patients. Impaired vascular reactivity was not observed in aortic rings without leucocytes stimulated with serum from stroke patients or age-matched control patients with or without leucocytes. These data suggest that leucocyte-dependent altered aortic endothelium-dependent relaxation with stroke and the systemic consequences of stroke on vascular inflammation may occur in the aorta. Post-stroke inflammation has been linked to poor stroke outcomes. The vascular endothelium senses and responds to circulating factors, in particular inflammatory cytokines. Although stroke-associated local cerebrovascular dysfunction is well reported, the effects of a stroke on conduit artery function are not fully understood. We tested the hypothesis that serum from stroke patients triggers leucocyte-dependent aortic endothelial dysfunction that is associated with elevated concentrations of cytokines. Total leucocytes were isolated from healthy individuals, and the cells were incubated in serum from control subjects or stroke patients for 6 h. The quantity of cytokines in media was determined using an immunoassay. Vascular reactivity was determined by the rat aortic rings that were co-cultured with or without leucocytes and stimulated with serum samples from control subjects or stroke patients. Endothelium-dependent dilatation was significantly impaired in aortic rings co-cultured with leucocytes plus serum from stroke patients (50 ± 30 versus 85 ± 13%, P < 0.05) versus serum from control subjects. In contrast, no difference was observed in aortic function stimulated with serum from control subjects or stroke patients without total leucocytes. Likewise, total leucocyte-derived cytokine concentrations were significantly increased in a time-dependent manner on stimulation with serum from stroke patients (P < 0.05). These observations support the concept that the increased response of leucocytes drives the development of stroke-associated vascular endothelial dysfunction. As such, pharmacologically targeting the source of inflammatory cytokines might alleviate stroke-associated peripheral vascular dysfunction.

Could Biomarkers Direct Therapy for the Septic Patient?

Sepsis is a serious medical condition caused by a severe systemic inflammatory response to a bacterial, fungal, or viral infection that most commonly affects neonates and the elderly. Advances in understanding the pathophysiology of sepsis have resulted in guidelines for care that have helped reduce the risk of dying from sepsis for both children and older adults. Still, over the past three decades, a large number of clinical trials have been undertaken to evaluate pharmacological agents for sepsis. Unfortunately, all of these trials have failed, with the use of some agents even shown to be harmful. One key issue in these trials was the heterogeneity of the patient population that participated. What has emerged is the need to target therapeutic interventions to the specific patient's underlying pathophysiological processes, rather than looking for a universal therapy that would be effective in a "typical" septic patient, who does not exist. This review supports the concept that identification of the right biomarkers that can direct therapy and provide timely feedback on its effectiveness will enable critical care physicians to decrease mortality of patients with sepsis and improve the quality of life of survivors.