Leukocyte rolling and extravasation in surgical inflammation after mechanical and laser-induced trauma in human patients

Abstract

Acute inflammations main characteristics are exudation of fluid and plasma proteins and emigration of leukocytes, predominantly neutrophils into inflamed tissue. We have previously demonstrated that leukocyte extravasation can be directly monitored in human patients in vivo after tunnel cataract operation, but at the same time we noticed that only certain manipulations trigger also leukocyte extravasation. To define the type of surgical manipulations triggering leukocyte extravasation, we tested a set of surgical manipulations affecting distinct anatomical components of the conjunctiva. This set included various combinations of epithelial, nerve, and/or blood vessel damage. Manipulations tested here were surgical conjunctival biopsy, low-energy Argon laser treatment (80 mJ) closing a venule temporarily, high-energy argon laser treatment (480 mJ) to occlude a venule firmly, and 193 nm eximer laser-based conjunctival phototherapeutic keratectomy (160 mJ). These manipulations were compared to previous findings on conjunctival inflammation following the standard cataract operation. In mechanical trauma models (cataract operation and conjunctival biopsy) clinical signs of inflammation, number of leukocytes rolling, and number of tissue emigrated leukocytes were notably higher compared to pre-operative levels on one day after the operation. No specific anatomical triggering component for inflammation, including epithelial, nerve, and/or blood vessel damage, was indentified, but rather the trauma mechanism itself appeared to be an essential factor. Surprisingly, in laser-induced traumas no increase in number of rolling cells, rolling velocity slowing, or elevation of tissue emigrated leukocytes took place compared to pre-operative levels. These findings suggest that laser-induced traumas differ fundamentally from the mechanical traumas at all levels of leukocyte extravasation cascade, and at least in our setup, inflammatory reaction can be avoided or triggered depending on surgical method used.