Neutrophil functional abnormalities in diabetes mellitus patients with or without periodontal disease
Karima, Mamdouh M.
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The purpose of this study was to evaluate neutrophil mediated inflammation in diabetes mellitus, and to determine the role of periodontitis in the modulation of the systemic inflammatory response. The level of superoxide production from neutrophils obtained from diabetes mellitus patients with or without periodontal disease and healthy controls was compared. Superoxide production was assessed by a superoxide dismutase inhibitable cytochrome c reduction assay in response to 1[mega] fMLP or 200nM PMA. Superoxide production from diabetic neutrophils was higher by 2.0 to 3.0 fold compared to healthy controls both in resting and fMLP or PMA stimulated cells. Furthermore, neutrophils from diabetics with moderate and severe chronic periodontitis exhibited higher superoxide production compared to diabetics with mild chronic periodontitis and diabetics without chronic periodontitis. There was no difference between type 1 or type 2 diabetes mellitus patients with almost equal blood level of glycosylated hemoglobin (HbA1cAIc) and in terms of neutrophil superoxide production. Further, we observed that increased neutrophil superoxide production was not associated with smoking both in healthy controls and in DM patients. The present study determines the role of diabetic control and AGE in neutrophil priming. We evaluated superoxide production by healthy control and diabetic neutrophils in response to 1.0 mg/ml CML-albumin (AGE). CML-albumin induced a dose-dependent increase in neutrophil superoxide production from both healthy subjects and diabetic patients. Neutrophil superoxide was higher by 2.0 fold in diabetic patients compared to healthy controIs in response to AGE. When neutrophils were incubated with CML-albumin for 6 minutes as a priming agent, followed by stimulation with a second agonist, fMLP or PMA, superoxide production was sharp and rapid and was 3.0 to 4.0 fold higher in diabetic neutrophils compared to healthy controls. Within the diabetic group, superoxide generation was similar in all chronic periodontitis patients with respect to combined effect of CML-albumin plus fMLP or PMA. The next step was to determine the effect of CML-albumin on PKC activity in neutrophils from healthy controls versus diabetic patients with or without chronic periodontitis. PKC activity was measured by the phosphorylation of histone with radiolabeled ATP ([[upsilon]-superscript 32P] ATP). The activity of Ca-dependent PKC in nentrophils from DM patients with or without chronic periodontitis was significantly higher than that in neutrophils from normal healthy subjects. Moreover, DM patients with severe chroonic periodontitis exhibited higher activity of Ca-dependent PKC in the membrane compartment compared to DM patients with mild and moderate chronic periodotitis and DM patients without chronic periodontitis in unstimulated and flVnP or PMA stimulated cells. Upon cell stimulation with CML-albumin or CML-albumin plus fMLP or PMA, there was no difference between the DM patients with different severities of periodontitis in the subcellular distribution of PKC activity. Finally, the existence of receptors for AGE had not been reported for neutrophils. We identified a receptor for AGE on both normal subjects and DM patients' neutrophils by western blot analysis using RAGE antibodies. Wether confirmed RAGE expression on neutrophils by western blot competition studies with a specific blocking peptide for a RAGE anti-peptide. Superoxide production from diabetics and healthy controls was blocked by RAGE antibody upon stimulation of the cells with CML-albumin. Quantification of RAGE in DM patients and healthy controls was similar and it appears that the receptor is constitutively expressed and to be independent of the disease process. These studies suggest that neutrophils from diabetic patients present a primed phenotype and the extent of priming correlates with diabetic control. Neutrophil priming in diabetes is associated with cell activation through AGE receptor identified on neutrophils.
PLEASE NOTE: This work is protected by copyright. Downloading is restricted to the BU community: please click Download and log in with a valid BU account to access. If you are the author of this work and would like to make it publicly available, please contact email@example.com.Thesis (D.Sc.)--Boston University, Goldman School of Dental Medicine, 2004 (Oral Biology)Includes bibliography (leaves 62-87).
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