Excess glucose induce trophoblast inflammation and limit cell migration through HMGB1 activation of Toll-Like receptor 4.

Abstract

Hyperglycemia increases the risk of preeclampsia. Hyperglycemia induces a placental trophoblast inflammatory (IL-1β, IL-6, IL-8), antiangiogenic (sFlt-1, sEndoglin), and anti-migratory profile. The IL-1β response is mediated via inflammasome activation by the damage-associated molecular pattern (DAMP), uric acid. The objective of this study was to determine the role of high-mobility group box-1 (HMGB1), a DAMP that activates Toll-like receptor 4 (TLR4), in human first trimester trophoblast responses to hyperglycemia. The trophoblast response to excess glucose under different oxygen tensions was also investigated. The human first trimester trophoblast cell line (Sw.71) was exposed to glucose mimicking normoglycemia (5mmol/L) and hyperglycemia (10mmol/L), either alone or with the TLR4 antagonist, LPS-RS; or the HMGB1 inhibitor, glycyrrhizin. Cells were also treated with glucose under hyperoxic (21% O2 ), normoxic (8% O2 ), and hypoxic (2% O2 ) conditions. Cell-free supernatants were assayed by ELISA and bioassays for inflammatory: IL-1β, IL-6, and IL-8; inflammasome-associated: uric acid and caspase-1; angiogenic: sEndoglin, sFlt-1, and PlGF; and the DAMP, HMGB1. Cell migration was measured using a two-chamber colormetric assay. Excess glucose triggered a trophoblast sterile inflammatory IL-8 and antimigratory response through HMGB1 activation of TLR4. The IL-1β and sFlt-1/PlGF response was TLR4-mediated, but HMGB1-independent, suggesting another DAMP may be involved. Hyperoxia rather than normoxia or hypoxia was a major driver of trophoblast dysfunction in response to excess glucose. The findings from this study indicate a novel mechanism by which hyperglycemia may impact trophoblast function, early placentation, and ultimately, pregnancy outcome.