Tumor necrosis factor-alpha expression and detection of apoptosis at the site of chronic periodontitis in AIDS patients

Comparative Evaluation of Serum Tumor Necrosis Factor α in Health and Chronic Periodontitis: A Case-Control Study

BACKGROUND

Tumor necrosis factor-alpha (TNF-α), a " major inflammatory cytokine," not only plays an important role in periodontal destruction but also is extremely toxic to the host. Till date, there are not many studies comparing the levels of TNF-α in serum and its relationship to periodontal disease.

AIM

Our study aimed to compare the serum TNF-α among the two study groups, namely, healthy controls and chronic periodontitis patients and establish a correlation between serum TNF-α and various clinical parameters. Hence, an attempt is made to estimate the level of TNF-α in serum, its relationship to periodontal disease and to explore the possibility of using the level of TNF-α in serum as a biochemical " marker" of periodontal disease.

MATERIALS AND METHODS

Forty individuals participated in the study and were grouped into two subgroups. Group A - 20 systemically and periodontally healthy controls. Group B - twenty patients with generalized chronic periodontitis. The serum samples were assayed for TNF-α levels by enzyme-linked immunosorbent assay method.

RESULTS

The mean serum TNF-α cytokines for Group B Generalized chronic periodontitis (GCP) was 2.977 ± 1.011, and Group A (healthy) was 0.867 ± 0.865. The range of serum TNF-α was from (0.867 to 2.977). Serum TNF-α cytokines had highly significant correlation with all clinical parameters (plaque index, probing pocket depth, clinical attachment loss, and gingival index) among all study participants (P = 0.001).

CONCLUSION

These observations suggest a positive association between periodontal disease and increased levels of TNF-α in serum. It can be concluded that there is a prospect of using the estimation of TNF-α in serum as a "marker" of periodontal disease in future. However, it remains a possibility that the absence or low levels of TNF-α in serum might indicate a stable lesion and elevated levels might indicate an active site but only longitudinal studies taking into account, the disease "activity" and "inactivity" could suggest the possibility of using TNF-α in serum as an "Indicator" of periodontal disease.

Oral infectious diseases: a potential risk factor for HIV virus recrudescence?

As the highly active antiretroviral therapy (HAART) has transitioned human immunodeficiency virus (HIV) infection into a 'chronic disease' management strategy, there is growing evidence that infection with non-HIV pathogens in HIV+ patients may have important public health implications in undermining HAART success and acquired immunodeficiency syndrome progression. Several bacterial and host cell products during infections with non-HIV pathogens have shown the capacity to regulate HIV replication in latently infected cells. A high prevalence of oral infections caused by bacteria, viruses and fungi has been described in HIV+ patients, including periodontal disease. The oral cavity appears to be a site of HIV pathogenesis and potential reservoir for the disease as HIV RNA and DNA forms are present in saliva as well as in gingival crevicular fluid, and oral epithelial cells are susceptible to either cell free or cell-associated HIV infection. The clinical and biological bases of potential associations between chronic oral inflammatory disorders, such as periodontal disease, and exacerbation of HIV viraemia have received little attention. This review attempts to evaluate the current understanding of HIV reactivation as a result of co-infection and/or inflammation induced by non-HIV pathogens in HIV-infected patients, and presents a hypothetic model about the potential role of periodontitis as a global oral infection that potentially contributes to HIV recrudescence.

Role of macrophages in LPS-induced osteoblast and PDL cell apoptosis

In periradicular lesions and periodontal disease, bacterial invasion leads to chronic inflammation resulting in disruption of the structural integrity of the periodontal ligament and progressive alveolar bone destruction. The pathogenesis of these conditions has been attributed not only to bacterial-induced tissue destruction but also to a defect in periodontal tissue repair. Accumulated data have also shown that lipopolysaccharide (LPS) can directly induce cell death or apoptosis in many cell types, including macrophages, osteoblasts, vascular endothelial cells, hepatocytes and myocytes. The present study hypothesized that bacterial LPS-induced apoptosis in osteoblasts and periodontal ligament fibroblasts (PDL cells) is an important contributing factor to the defect in periodontal tissue repair in periodontal and periapical disease. Macrophages have been shown to respond to bacterial LPS by increasing the production of proinflammatory cytokines. In addition, large numbers of macrophages are present in inflamed periodontal tissue. We speculated that macrophages were a potential candidate cell for mediating apoptosis in osteoblasts and PDL cells in response to bacteria-derived LPS. The macrophage-like cell line, RAW 264.7, was stimulated with LPS, and the conditioned medium was used to treat osteoblasts and PDL cells. Bacterial LPS had no direct apoptotic effect on mouse osteoblasts or PDL cells, whereas the conditioned medium from LPS-activated macrophages was able to induce apoptosis in these cells. To evaluate the contribution of tumor necrosis factor-alpha (TNF-alpha) released from macrophages on osteoblast and PDL cell apoptosis, cells were incubated with conditioned medium from LPS-treated macrophages in the presence and absence of anti-TNF-alpha neutralizing antibodies. TNF-alpha neutralizing antibody pretreatment inhibited the effect of conditioned medium from LPS-treated macrophages on osteoblast and PDL cell apoptosis in a dose-dependent manner. These results suggest that LPS could indirectly induce apoptosis in osteoblasts and PDL cells through the induction of TNF-alpha release from macrophages. These studies provide insight into a potential mechanism by which bacterial-derived LPS could contribute to defective periodontal and bone tissue repair in periodontal and periapical disease.