Mini-laparotomy and full laparotomy, but not laparoscopy, alter hepatic macrophage populations in a rat model

Immune function is better preserved by laparoscopic versus conventional surgery. Numerous mediators of the systemic trauma response are synthesized and/or regulated by the liver. However, it has been stated that the advantages of laparoscopic surgery are no more obvious when conventional operations are performed via mini-laparotomy. We set out to compare the impact of laparoscopy and mini- and full laparotomy on the hepatic macrophage populations.

Male Lewis rats were subjected to anesthesia alone (control), mini-laparotomy (1 cm), full laparotomy (7 cm), or laparoscopy for 60 min. Endpoints were the total protein in the peritoneal lavage fluid, hepatic ED-1 cells (recruited monocytes), hepatic ED-2 cells (Kupffer cells), the expression of OX-6 in the liver, and C-reactive protein (CRP) in plasma.

Protein in the peritoneal lavage fluid increased significantly after all interventions. Full laparotomy was accompanied by an enhancement in ED-1-positive monocytes in the liver parenchyma compared to all other groups (p < 0.001). Mini- and full laparotomy led to an increase in ED-2-positive Kupffer cells (p < 0.001). Laparoscopy did not affect the number of monocytes/macrophages. There was no significant alteration of OX-6 expression in either group. No change in the cellular composition in the periportal fields was observed. The CRP plasma levels did not significantly differ between groups.

Laparoscopy completely prevents hepatic macrophage populations from expansion and normal cell disposition is preserved. Laparotomy, irrespective of incision size, increases the number of Kupffer cells. Moreover, full laparotomy, but not mini-laparotomy or laparoscopy, causes an increase in hepatic monocyte recruitment. The regulating pathways after surgery differ from other immunologic challenges, such as sepsis, in which immunocompetent cells accumulate and are stimulated in the periportal fields.