Background: Polymorphonuclear leukocytes (PMNs) from subjects with localized aggressive periodontitis (LAgP) present multiple functional abnormalities associated with a phenotypically primed PMN phenotype. Local inflammation is characterized by hypoxia, which leads to increased production of superoxide (O(2)(-)) by PMNs. Ceruloplasmin (CP) is also induced by hypoxia and inflammation. The aim of this study was to investigate the role of CP in O(2)(-) generation in PMNs from healthy subjects and patients with LAgP.
Methods: PMNs were isolated from healthy subjects and those with LAgP (N = 36). Superoxide was measured by cytochrome-C reduction at 550 nm. Intracellular CP expression was analyzed by real-time polymerase chain reaction and Western blotting. Serum levels of CP were measured by enzyme-linked immunosorbent assay. Intracellular iron ion conversion was spectrophotometrically determined by measuring the absorbance of sigma-phenanthroline at 510 nm.
Results: O(2)(-) generation was significantly higher in LAgP PMNs before and after stimulation with formyl-methionyl-leucyl-phenylalanine (100 nM). CP expression in PMNs and CP levels in serum were significantly higher in subjects with LAgP compared to the PMNs and serum samples from matched healthy donors (P <0.05). LAgP PMNs also had significantly higher levels of Fe(3+) and lower levels of Fe(2+) compared to healthy PMNs (P <0.05), suggesting increased iron conversion. Exogenous CP treatment of healthy PMNs resulted in significant increases in O(2)(-) generation and iron ion conversion similar to LAgP PMNs.
Conclusion: LAgP PMNs are primed to express higher levels of CP, leading to hypoxia-mediated O(2)(-) generation in PMNs and increased oxidative stress and neutrophil-mediated tissue injury in LAgP.