Pharmacological Inhibition and Genetic Deletion of Cystathionine Gamma-Lyase in Mice Protects against Organ Injury in Sepsis: A Key Role of Adhesion Molecules on Endothelial Cells

Substance P Promotes Leukocyte Infiltration in the Liver and Lungs of Mice with Sepsis: A Key Role for Adhesion Molecules on Vascular Endothelial Cells

Substance P (SP), encoded by the Tac1 gene, has been shown to promote leukocyte infiltration and organ impairment in mice with sepsis. Neurokinin-1 receptor (NK1R) is the major receptor that mediates the detrimental impact of SP on sepsis. This investigation studied whether SP affects the expression of adhesion molecules, including intercellular cell adhesion molecule-1 (ICAM1) and vascular cell adhesion molecule-1 (VCAM1) on vascular endothelial cells in the liver and lungs, contributing to leukocyte infiltration in these tissues of mice with sepsis. Sepsis was induced by caecal ligation and puncture (CLP) surgery in mice. The actions of SP were inhibited by deleting the Tac1 gene, blocking NK1R, or combining these two methods. The activity of myeloperoxidase and the concentrations of ICAM1 and VCAM1 in the liver and lungs, as well as the expression of ICAM1 and VCAM1 on vascular endothelial cells in these tissues, were measured. The activity of myeloperoxidase and the concentration of ICAM1 and VCAM1 in the liver and lungs, as well as the expression of ICAM1 and VCAM1 on vascular endothelial cells in these tissues, increased in mice with CLP surgery-induced sepsis. Suppressing the biosynthesis of SP and its interactions with NK1R attenuated CLP surgery-induced alterations in the liver and lungs of mice. Our findings indicate that SP upregulates the expression of ICAM1 and VCAM1 on vascular endothelial cells in the liver and lungs, thereby increasing leukocyte infiltration in these tissues of mice with CLP surgery-induced sepsis by activating NK1R.

Kupffer Cell Inactivation Alters Endothelial Cell Adhesion Molecules in Cecal Ligation and Puncture-Induced Sepsis

The activation of Kupffer cells, resident macrophages in the liver, is closely associated with the inflammatory response during sepsis, which leads to multiple-organ failure. However, how Kupffer cell activation affects adhesion molecules (ICAM-1 and VCAM-1) in sepsis has not been determined. This study investigated Kupffer cell inactivation's (by gadolinium chloride; GdCl3) effects on adhesion molecule expression in CLP-induced sepsis. The induction of sepsis resulted in increased expression of liver and lung ICAM-1 and VCAM-1. GdCl3 pretreatment significantly decreased liver ICAM-1 expression but had no effect on VCAM-1 expression. In contrast, GdCl3 pretreatment had no effect on sepsis-induced increased adhesion molecule expression in the lungs. Similarly, the immunoreactivity of ICAM-1 was decreased in liver sinusoidal endothelial cells but increased in pulmonary endothelial cells in septic mice pretreated with GdCl3. Further, GdCl3 pretreatment had no effect on the immunoreactivity of VCAM-1 in endothelial cells of the liver and lungs. Hence, the findings of this study demonstrate the differential effects of Kupffer cell inactivation on liver and lung adhesion molecules and suggest the complexity of their involvement in the pathophysiology of sepsis.