Effect of micro-osteoperforations on the rate of tooth movement.

INTRODUCTION: Our objectives were to study the effect of micro-osteoperforations on the rate of tooth movement and the expression of inflammatory markers. METHODS: Twenty adults with Class II Division 1 malocclusion were divided into control and experimental groups. The control group did not receive micro-osteoperforations, and the experimental group received micro-osteoperforations on 1 side of the maxilla. Both maxillary canines were retracted, and movement was measured after 28 days. The activity of inflammatory markers was measured in gingival crevicular fluid using an antibody-based protein assay. Pain and discomfort were monitored with a numeric rating scale. RESULTS: Micro-osteoperforations significantly increased the rate of tooth movement by 2.3-fold; this was accompanied by a significant increase in the levels of inflammatory markers. The patients did not report significant pain or discomfort during or after the procedure, or any other complications. CONCLUSIONS: Micro-osteoperforation is an effective, comfortable, and safe procedure to accelerate tooth movement and significantly reduce the duration of orthodontic treatment.

P. gingivalis and E. coli lipopolysaccharides exhibit different systemic but similar local induction of inflammatory markers.

BACKGROUND: Porphyromonas gingivalis is a Gram-negative bacterium that is an important etiologic agent of human adult periodontitis. The goal of the study was to test the hypothesis that two isoforms of P. gingivalis lipopolysaccharide (PgLPS), PgLPS(1435)(/1449) and PgLPS(1690), exhibit differences in their capacity to stimulate systemic versus local responses compared to Escherichia coli lipopolysaccharide (LPS). METHODS: LPS was inoculated into the scalp of mice, and the response was measured locally at the site of inoculation and systemically in the heart/aorta. Vascular cell adhesion molecule (VCAM)-1 was assessed at the protein level by enzyme-linked immunosorbent assay, and VCAM-1, E-selectin, and intercellular adhesion molecule (ICAM)-1 were assessed at the RNA level of the RNase protection assay. Serum tumor necrosis factor-alpha (TNF-alpha) levels were also measured. RESULTS: E. coli LPS and both isoforms of P. gingivalis LPS were relatively potent in stimulating the expression of inflammatory markers, with E. coli LPS being more potent. In contrast, when the systemic response was measured in the heart/aorta, E. coli LPS, but not P. gingivalis LPS, significantly induced inflammatory markers. At moderate to low doses (1 and 10 microg per injection), serum TNF-alpha levels were minimally induced by P. gingivalis LPS compared to E. coli LPS. CONCLUSIONS: Both forms of P. gingivalis LPS stimulated an inflammatory response when injected into connective tissue but were minimally stimulatory when a systemic response was measured. In contrast, E. coli LPS was a potent stimulus at the systemic and local levels.

Advanced glycation end products induce apoptosis in fibroblasts through activation of ROS, MAP kinases, and the FOXO1 transcription factor.

Advanced glycation end products (AGEs) are elevated in aged and diabetic individuals and are associated with pathological changes associated with both. Previously we demonstrated that the AGE N(epsilon)-(carboxymethyl)lysine (CML)-collagen induced fibroblast apoptosis through the cytoplasmic and mitochondrial pathways and the global induction of proapoptotic genes. In the present study we investigated upstream mechanisms of CML-collagen-induced apoptosis. CML-collagen induced activation of the proapoptotic transcription factor FOXO1 compared with unmodified collagen. When FOXO1 was silenced, CML-collagen-stimulated apoptosis was reduced by approximately 75% compared with fibroblasts incubated with nonsilencing small interfering RNA, demonstrating the functional significance of FOXO1 activation (P < 0.05). CML-collagen but not control collagen also induced a 3.3-fold increase in p38 and a 5.6-fold increase in JNK(1/2) activity (P < 0.05). With the use of specific inhibitors, activation of p38 and JNK was shown to play an important role in CML-collagen-induced activation of FOXO1 and caspase-3. Moreover, inhibition of p38 and JNK reduced CML-collagen-stimulated apoptosis by 48 and 57%, respectively, and by 89% when used together (P < 0.05). In contrast, inhibition of the phosphatidylinositol 3-kinase/Akt pathway enhanced FOXO1 activation. p38 and JNK stimulation by CML-collagen was almost entirely blocked when formation of ROS was inhibited and was partially reduced by NO and ceramide inhibitors. These inhibitors also reduced apoptosis to a similar extent. Together these data support a model in which AGE-induced apoptosis involves the formation of ROS, NO, and ceramide and leads to p38 and JNK MAP kinase activation, which in turn induces FOXO1 and caspase-3.

Advanced glycation end products stimulate osteoblast apoptosis via the MAP kinase and cytosolic apoptotic pathways.

We have previously shown that diabetes significantly enhances apoptosis of osteoblastic cells in vivo and that the enhanced apoptosis contributes to diabetes impaired new bone formation. A potential mechanism is enhanced apoptosis stimulated by advanced glycation end products (AGEs). To investigate this further, an advanced glycation product, carboxymethyl lysine modified collagen (CML-collagen), was injected in vivo and stimulated a 5-fold increase in calvarial periosteal cell apoptosis compared to unmodified collagen. It also induced apoptosis in primary cultures of human or neonatal rat osteoblastic cells or MC3T3-E1 cells in vitro. Moreover, the apoptotic effect was largely mediated through RAGE receptor. CML-collagen increased p38 and JNK activity 3.2- and 4.4-fold, respectively. Inhibition of p38 and JNK reduced CML-collagen stimulated apoptosis by 45% and 59% and by 90% when used together (P<0.05). The predominant apoptotic pathway induced by CML-collagen involved caspase-8 activation of caspase-3 and was independent of NF-kappaB activation. When osteoblastic cells were exposed to a long-term low dose incubation with CML-collagen, there was a higher degree of apoptosis compared to short-term incubation. In more differentiated osteoblastic cultures, apoptosis was enhanced even further. These results indicate that advanced glycation end products, which accumulate in diabetic and aged individuals, may promote apoptosis of osteoblastic cells and contribute to deficient bone formation.

TNF-alpha in vivo stimulates apoptosis in fibroblasts through caspase-8 activation and modulates the expression of pro-apoptotic genes.

Apoptosis of matrix producing cells is common among many inflammatory diseases. The goal of the present study was to examine the apoptotic effects of tumor necrosis factor-alpha (TNF-alpha) on fibroblastic cells in vivo and to investigate the role of different caspases in this process. This was accomplished in vivo by subcutaneous injection of TNF-alpha in mice. The direct effects of TNF-alpha on fibroblast apoptosis were studied in vitro with normal diploid human fibroblasts. The results indicate that TNF-alpha in vivo induces apoptosis of fibroblasts. By RNase protection assay, we demonstrated that TNF-alpha stimulates expression of 12 apoptotic genes. Fluorometric studies demonstrated that TNF-alpha in vivo predominantly increased caspase-8 and -3 activity and by use of specific inhibitors, the activation of caspase-3 was shown to be initiated by caspase-8 with only a minor contribution from caspase-9. Thus, TNF-alpha acts to modulate the expression of many genes that favors apoptosis of fibroblastic cells, which is dependent mostly upon signaling through caspase-8.

Influence of diabetes on the exacerbation of an inflammatory response in cardiovascular tissue.

Coronary artery disease results from an inflammatory process in blood vessels of afflicted individuals. This process is accelerated with diabetes for reasons that are largely unknown. Recent evidence indicates that infection at sites remote from the heart leads to bacteremia and endotoxemia, thereby stimulating systemic inflammation, which represents an important risk factor for atherosclerosis. We examined the inflammatory response of the heart/aorta of diabetic db/db mice that develop type II diabetes. Subcutaneous inoculation of lipopolysaccharide was used to mimic a local infection. This stimulated an up-regulation of adhesion molecules, cytokines, and chemokines via an endotoxemia that was significantly more rapid and more pronounced in the diabetic compared with normal mice. The 13- to 30-fold induction of key proinflammatory molecules in the heart/aorta of diabetic mice even exceeded that at the site of inoculation. Given that infection, bacteremia, and endotoxemia are relatively frequent events in humans, these results identify a putative mechanism for increased cardiovascular heart disease in diabetes.