MMP-2 salivary activity in type 2 diabetes mellitus patients

Abstract

Background: Type 2 diabetes mellitus (T2DM) and periodontitis are chronic inflammatory diseases with a bidirectional relationship. The uncontrolled levels of glucose in T2DM patients change the pathophysiology and balance of inflammatory mediators. Matrix Metalloproteinase-2 (MMP-2) is a zinc-dependent endopeptidase that is responsible for tissue remodeling and degradation of the extracellular matrix in periodontal tissue. Therefore, the uncontrolled levels of glucose in T2DM could lead to an imbalance in MMP-2 activity in saliva, favoring the development of periodontitis.

Methods: Ninety-seven T2DM patients from Hospital Dr. Donato Alarcon were included in the study. Following clinical examination, the patients were classified into four groups according to the presence and degree of periodontal disease and glycemic control. Blood and whole saliva samples (WSS) were collected from each patient. Blood samples were used for Hba1c and polymorphonuclear cells count determination, while WSS were used to determine MMP-2 activity, TIMP-1 and nitrite. MMP-2 activity was determined by zymography. TIMP-1 were determined by Western blotting, and nitric oxide (NO) levels were determined by the Griess method.

Results: Of the 97 patients with T2DM, 66 had periodontitis of different severities: 18 patients had mild periodontitis, 15 had moderate and 33 had severe. Salivary MMP-2 activity, HbA1c and TIMP-1 were positively correlated with the severity of periodontitis. On the other hand, the increase in HbA1c was negatively correlated with MMP-2 activity and quantity of TIMP-1 but was positively correlated with nitrite levels.

Conclusions: T2DM with glycemic uncontrol conditions, distinct clinical alterations in periodontal tissue were identified, including a decrease in the gingival redness, increased the clinical attachment loss and imbalance of MMP-2/TIMP-1, as the possible causes of disorders promoting the progression of periodontitis. Accelerated periodontitis development with poor glycemic uncontrol likely results from the altered response of host defenses and decreased activity of polymorphonuclear cells. Taken together, these findings identify MMP-2 as a promising molecular market for periodontitis.

Keywords: Diabetes mellitus type 2; MMP-2; Periodontitis; TIMP-1.

Fig. 1

Representative zymography image of gelatinolytic activity of MMP-2 in saliva; lane 1 (Periodontally Healthy), lane 2 (Mild Periodontitis), lane 3 (Moderate Periodontitis), lane 4 (Severe Periodontitis) and lane 5 (MCF7 cell line supernatant positive control)

Fig. 2

Gelatinolytic activity detected by zymography assay in WSS. a Increased MMP-2 gelatinolytic activity was found in Severe Periodontitis in comparison to that of Healthy individuals (*p < 0.05). b TIMP-1 were detected by Western blot assay in WSS, and a higher quantity was found in Severe Periodontitis compared to that of healthy individuals (*p < 0.05)

Fig. 3

Levels of HbA1c negatively correlate with the activity of MMP-2 and TIMP-1 in WSS. a There was a higher percentage of HbA1c in increased Severe Periodontitis in comparison to that of healthy individuals (*p < 0.05). b The total count of polymorphonuclear cells increased in patients with HbA1c > 8% compared with that of patients with good control < 5.9% (*p < 0.05). c Activity of proMMP2 and MMP-2 decreased in the WSS of patients with a higher percentage of HbA1c (> 8%) compared to that of patients with good glycemic control (< 5.9) *p < 0.05. d TIMP-1 in the WSS of patients with T2DM compared with that of patients with different percentages of HbA1c (*p < 0.05)

Fig. 4

Levels of nitrite in WSS correlate with HbA1c. Micromolar concentrations of nitrite were calculated from the standard curve constructed with sodium nitrite as a reference compound. The data are representative of three independent experiments; (*p < 0.05) significantly different between poor glycemic control (> 8% HbA1c) and good glycemic control (< 5.9% HbA1c)