COX-2 and E-selectin expression evaluation after acute normovolemic hemodilution

Introduction

In recent years there has been increasing evidence that resuscitation strategy with different fluids can have widely divergent impacts on the immune response. This study was undertaken to determine the COX-2 and E-selectin expression in the lung tissue in the swine model during an acute normovolemic hemodilution (ANH) procedure with hydroxyethyl starch (HES 130/0,4), normal saline solution (NS) or gelatin (GEL).

Methods

Twenty-eight pigs were anesthetized, instrumented and randomized into four groups: control, ANH + HES, ANH + NS and ANH + GEL. Animals in the ANH group were submitted to ANH to a target hematocrit of 15% with volume replacement performed with HES and GEL at a 1:1 ratio and NS at a 3:1 ratio. The withdrawn blood was returned to the animals 120 minutes after the end of hemodilution. After euthanasia, the chest cavity was opened and the lobes of the lung were removed and fixed in 10% formaldehyde solution. After the histopathological assessment, the lungs were prepared with antibody anti-COX-2 and E-selectin. The pathologist, who was blinded to the experimental protocol, scored the expression of COX-2 and E-selectin by semiquantitatively evaluating the intensity (absent – 0, weak – 1, moderate – 2 and strong – 3) and incidence (absent – 0, 10% – 1, 10 to 50% – 2, 50 to 75% – 3 and 75 to 100% – 4) of positively stained endothelium of the interstitial pulmonary microvasculature. The total index was obtained from the sum of the frequency and the intensity scores. For the immunohistochemistry score, a nonparametric Fisher's test was used.

Results

The intravascular leukocytes expression of COX-2 in the NS group was weak and differed significantly only from the GEL group (P < 0.05). In contrast, groups HES and GEL showed a moderate and strong COX-2 expression, respectively, which was different from the control group (P < 0.05, P < 0.001, respectively). E-selectin expression in the HES and GEL groups differed significantly from the control. In the HES and GEL groups, a weak to moderate expression of E-selectin (P < 0.05, P < 0.001) was detected in endothelial cells from pulmonary arteries and veins.

Conclusion

Fluid replacement during ANH increased inflammation determined by an increase in COX-2 and E-selectin expression.