IADR Abstract Archives
5-lipoxygenase Regulates SMG Pro-Inflammatory Cytokine Expression in a Sex-Dependent Manner
Objectives: Alox5 is the gene coding for 5-lipoxygenase (5-LOX), the rate-limiting enzyme in leukotriene (i.e., LTA4) and pro-resolving lipid mediators (i.e., RvD1 and LXA4) biosynthesis. The role for 5-LOX has been established by demonstrating that 5-LOX expression and lipid mediator formation are increased in various experimental models of inflammation, in which inhibition of the 5-LOX pathway results in a significant reduction of tissue injury. Considering that 5-LOX inhibition or disruption of the 5-LOX gene confers protection against inflammation, 5-LOX deficiency might be expected to confer protection in salivary glands. Therefore, the goal of our study is to determine whether submandibular glands (SMG) from 5-LOX knockout (5-LOX-/-) mice could resist lipopolysaccharide (LPS)-induced inflammation or have an exacerbated response.
Methods: 5-LOX-/- and wild type C57BL/6J mice were treated with PBS (10 uL/g) and LPS (10 mg/kg), after 24 h, mice were anesthetized with 100 mg/kg ketamine and 5 mg/kg xylaxine and euthanized. SMG were dissected, frozen, sectioned and stained with H&E and histopathological analysis conducted. Additionally, frozen SMGs were used for qPCR analysis to detect relative gene expression of pro-inflammatory cytokines. Finally, saliva secretion in response to pilocarpine-HCl/PBS (10 mg/kg) was measured.
Results: 5-LOX-/- had no effect on immune cell infiltration between groups of mice injected with LPS. Interestingly, pro-inflammatory cytokines genes (e.g., TNF-α and IL-1β) were significantly upregulated in LPS-treated female 5-LOX-/- mice as compared to LPS-treated wild type or male 5-LOX-/- mice. Regarding saliva secretion, 5-LOX-/- and C57BL/6J mice of both sexes showed similar extent of salivary gland dysfunction when injected with LPS.
Conclusions: Absence of 5-LOX did not affect saliva secretion or cause histopathological changes in SMG. However, we observed striking differences in LPS-mediated upregulation of pro-inflammatory cytokines in SMG from female but not male 5-LOX-/- mice as compared to LPS-treated controls. These data support the notion that 5-LOX-mediated inflammatory responses in SMG are sex-dependent.
Methods: 5-LOX-/- and wild type C57BL/6J mice were treated with PBS (10 uL/g) and LPS (10 mg/kg), after 24 h, mice were anesthetized with 100 mg/kg ketamine and 5 mg/kg xylaxine and euthanized. SMG were dissected, frozen, sectioned and stained with H&E and histopathological analysis conducted. Additionally, frozen SMGs were used for qPCR analysis to detect relative gene expression of pro-inflammatory cytokines. Finally, saliva secretion in response to pilocarpine-HCl/PBS (10 mg/kg) was measured.
Results: 5-LOX-/- had no effect on immune cell infiltration between groups of mice injected with LPS. Interestingly, pro-inflammatory cytokines genes (e.g., TNF-α and IL-1β) were significantly upregulated in LPS-treated female 5-LOX-/- mice as compared to LPS-treated wild type or male 5-LOX-/- mice. Regarding saliva secretion, 5-LOX-/- and C57BL/6J mice of both sexes showed similar extent of salivary gland dysfunction when injected with LPS.
Conclusions: Absence of 5-LOX did not affect saliva secretion or cause histopathological changes in SMG. However, we observed striking differences in LPS-mediated upregulation of pro-inflammatory cytokines in SMG from female but not male 5-LOX-/- mice as compared to LPS-treated controls. These data support the notion that 5-LOX-mediated inflammatory responses in SMG are sex-dependent.