Hyperbaric oxygen preconditioning ameliorates blood-brain barrier damage induced by hypoxia through modulation of tight junction proteins in an in vitro model

Abstract

AimTo explore the effects of hyperbaric oxygen preconditioning (HBOP) on the permeability of blood-brain barrier (BBB) and expression of tight junction proteins under hypoxic conditions in vitro.MethodsA BBB in vitro model was constructed using the hCMEC/D3 cell line and used when its trans-endothelial electrical resistance (TEER) reached 80-120 Ω · cm2 (tested by Millicell-Electrical Resistance System). The cells were randomly divided into the control group cultured under normal conditions, the group cultured under hypoxic conditions (2%O2) for 24 h (hypoxia group), and the group first subjected to HBOP for 2 h and then to hypoxia (HBOP group). Occludin and ZO-1 expression were analyzed by immunofluorescence assay.ResultsNormal hCMEC/D3 was spindle-shaped and tightly integrated. TEER was significantly reduced in the hypoxia (P = 0.001) and HBOP group (P = 0.014) compared to control group, with a greater decrease in the hypoxia group. Occludin membranous expression was significantly decreased in the hypoxia group (P = 0.001) compared to the control group, but there was no change in the HBOP group. ZO-1 membranous expression was significantly decreased (P = 0.002) and cytoplasmic expression was significantly increased (P = 0.001) in the hypoxia group compared to the control group, although overall expression levels did not change. In the HBOP group, there was no significant change in ZO-1 expression compared to the control group.ConclusionHyperbaric oxygen preconditioning protected the integrity of BBB in an in vitro model through modulation of occludin and ZO-1 expression under hypoxic conditions.

Cell Culture Effects of Altered Oxygen Levels and Hyperbaric Treatment In Vitro

“…In the in vitro model of blood-brain barrier, brain microvascular endothelial cells can be cultured and trans-endothelial electric potential, as a measure of barrier function, can be evaluated in different oxygen circumstances [34]. Mainly cell interactions, tight junctions and endothelial-pericyte interactions are damaged in blood-brain barrier dysfunction.…”

“…Latest in vitro studies demonstrated that hypoxic damage of blood-brain barrier may be reversed via HBOT [34]. Hypoxia induced cellular endothelial fragmentation and impair of cell adhesion molecular.…”

“…Hypoxia induced cellular endothelial fragmentation and impair of cell adhesion molecular. On the contrary, HBOT after hypoxia was able to attenuate the effects and improve cellular junctions [34]. These data have very important message to clinical trials, as HBOT may have undistinguishable role in stroke treatment in the acute clinical phase (Figure 3) [39].…”

“…Interesting in vitro model for burned skin evolved ex vivo available burned skin tissues [50]. Recently, HBOT has been emerged for the treatment of chronic burn-related wounds as inflammatory cytokine release was decreased and bacterial viability also decreased in wound [34,35]. Burn models proved hyperemia (improved microcirculation) and reduced size of the burned lesions after HBOT of burn wounds [53].…”

Does generalized hypo-oxygenation (hypoxia) allow endotoxin into the brain through the blood brain barrier, thus increasing the risk for Parkinson disease?

“…Recent laboratory research reported that in vitro hypo-oxygenation (hypoxia) can result in permeability changes of the blood brain barrier (BBB) ( 1 ). Such changes provide an opportunity for molecules (substances) normally excluded by the BBB to enter the brain and possibly be trapped, especially after the integrity of the BBB is restored.…”