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[Influence of periodontal therapy on serum interleukin-6 and carotid metalloproteinases in animals with chronic periodontitis associated with atherosclerosis].

OBJECTIVE
To investigate the effect of periodontal mechanical treatment on serum interleukin-6 (IL-6) and carotid artery matrix metalloproteinase (MMP)-2 and MMP-9 expression in chronic periodontitis (CP) SD rats with atherosclerosis (As).


METHODS
Forty-four six-week-old male SD rats were randomly divided into three groups: control group (group A), As group (group B), As+CP group(group C). According to different periodontal interventions, group C was randomly subdivided into four groups: natural process group (C1), the periodontal mechanical treatment group (C2), the periodontal mechanical treatment+ local drugs group (C3), and the periodontal mechanical treatment+local and system drugs group (C4). Each group received the appropriate treatment and periodontal interventions. Serum IL-6 levels were determined by enzyme linked immunosorrbent assay (ELISA). MMP-2 and MMP-9 levels in the proximal aorta were examined by immunohistochemistry.


RESULTS
The gray value of MMP-2 and MMP-9 was basically the same in all groups. Compared with group A, the gray value of MMP-2 and MMP-9 of group B and C were decreased. C1 group showed the formation of atherosclerotic plaque and fibrous cap. Compared with group B (126.4 ± 2.0, 124.8 ± 2.8) , the gray value of group C1 (101.3 ± 2.4, 101.2 ± 4.1) was significantly weaker (P < 0.05). The staining depth of MMP-2 and MMP-9 of groups C1, C2, C3 and C4 were sequentially decreased, and the differences of gray value were statistically significant(P < 0.05). The levels of serum IL-6 in groups B and C1 increased gradually with time and became significantly higher than that of group A (P < 0.01). The levels of serum IL-6 in groups C2, C3, and C4 increased gradually and reached the peak 5 weeks after the establishment of model (P < 0.001). After that, the levels of serum IL-6 decreased gradually and was lower than baseline. The levels of serum IL-6 in groups C3 and C4 were significantly lower than that in group C2 7 weeks after the establishment of model(P < 0.01).


CONCLUSIONS
In rats with periodontitis and cardiovascular diseases, chronic periodontal inflammation may significantly increase the severity of As and promote the formation of atherosclerotic plaque. Mechanical periodontal therapy may cause short-term systemic inflammation and then reduce vascular inflammation in long term.With supplement use of local and systemic antibiotics, the mechanical periodontal therapy may get the vascular disease and systemic inflammation improved.