Detection of intracellular p24-positive macrophages in gingival crevicular fluid from periodontal lesions of stage IV AIDS patients

Antiproliferative Properties of Type I and Type II Interferon

The clinical possibilities of interferon (IFN) became apparent with early studies demonstrating that it was capable of inhibiting tumor cells in culture and in vivo using animal models. IFN gained the distinction of being the first recombinant cytokine to be licensed in the USA for the treatment of a malignancy in 1986, with the approval of IFN-α2a (Hoffman-La Roche) and IFN-α2b (Schering-Plough) for the treatment of Hairy Cell Leukemia. In addition to this application, other approved antitumor applications for IFN-α2a are AIDS-related Kaposi's Sarcoma and Chronic Myelogenous Leukemia (CML) and other approved antitumor applications for IFN-α2b are Malignant Melanoma, Follicular Lymphoma, and AIDS-related Kapoisi's Sarcoma. In the ensuing years, a considerable number of studies have been conducted to establish the mechanisms of the induction and action of IFN's anti-tumor activity. These include identifying the role of Interferon Regulatory Factor 9 (IRF9) as a key factor in eliciting the antiproliferative effects of IFN-α as well as identifying genes induced by IFN that are involved in recognition of tumor cells. Recent studies also show that IFN-activated human monocytes can be used to achieve >95% eradication of select tumor cells. The signaling pathways by which IFN induces apoptosis can vary. IFN treatment induces the tumor suppressor gene p53, which plays a role in apoptosis for some tumors, but it is not essential for the apoptotic response. IFN-α also activates phosphatidylinositol 3-kinase (PI3K), which is associated with cell survival. Downstream of PI3K is the mammalian target of rapamycin (mTOR) which, in conjunction with PI3K, may act in signaling induced by growth factors after IFN treatment. This paper will explore the mechanisms by which IFN acts to elicit its antiproliferative effects and more closely examine the clinical applications for the anti-tumor potential of IFN.

Clinical model: interferons activate human monocytes to an eradicative tumor cell level in vitro

Eradicative levels of antitumor activity by cytokines and leukocytes have not yet been reached experimentally and are needed clinically. Only a limited number of human cancers respond to therapy with interferon (IFN), other cytokines, or mononuclear leukocytes despite significant antitumor activity in vitro. We studied the IFN and monocytic cell conditions that would lead to an eradicative effect using human cells in vitro. Targets of the IFN-activated monocytic cells were either four human tumor cell lines (human osteosarcoma [HOS], LOX melanoma, A549 lung tumor, and SNB-19 glioblastoma) or two diploid cell lines (WI38 and MRC5). An average of 30-90 colony-forming tumor target cells were cultured overnight in 96-well tissue culture plates prior to treatment with serially diluted IFN with or without activated elutriation-purified monocytes or lymphocytes. The target cell colonies were treated for 3 days. The colonies were then stained with crystal violet to determine the levels of antitumor activity. IFN-activated human monocytes reached an eradicative level (95%-100%) against three of four tumor cell lines. The eradicative level (1) was induced best in human monocytes activated by combined type I and II IFNs, (2) was effective against tumor cells that were growing for 24 h, (3) was specific for human tumors, as diploid human cells were not inhibited, and (4) required contact between the macrophage and the tumor cells. Also, for the first time, the minimal effective concentration (MEC) of IFNs to activate monocytes can approach those needed for antiviral activity. To our knowledge, this is the first report of near total eradication of many tumor cells, but not diploid cells, by IFN-activated monocytes. Because of its potency and specificity, the IFN-activated monocyte arm of the innate immune system may be a candidate for therapy of established tumors.

Oral transmission of HIV, reality or fiction? An update

Human immunodeficiency virus (HIV) and many other viruses can be isolated in blood and body fluids, including saliva, and can be transmitted by genital-genital and especially anal-genital sexual activity. The risk of transmission of HIV via oral sexual practices is very low. Unlike other mucosal areas of the body, the oral cavity appears to be an extremely uncommon transmission route for HIV. We present a review of available evidence on the oral-genital transmission of HIV and analyse the factors that act to protect oral tissues from infection, thereby reducing the risk of HIV transmission by oral sex. Among these factors we highlight the levels of HIV RNA in saliva, presence of fewer CD4+ target cells, presence of IgA antibodies in saliva, presence of other infections in the oral cavity and the endogenous salivary antiviral factors lysozyme, defensins, thrombospondin and secretory leucocyte protease inhibitor (SLPI).

Enhanced interleukin 1 beta, interleukin 6 and tumor necrosis factor alpha in gingival crevicular fluid from periodontal pockets of patients infected with human immunodeficiency virus 1

Loss of periodontal support and eventually tooth loss is a common finding among acquired immunodeficiency syndrome (AIDS) patients. The cause of this destruction may be an increase in periodontal disease activity at sites within the same individual and also may be related to an increase in the pro-inflammatory cytokines, diffused through the gingival crevicular sulcus in AIDS patients. A study was undertaken to determine the relative levels of the pro-inflammatory cytokines, interleukin 1 beta (IL-1 beta), IL-6, and tumor necrosis factor alpha (TNF-alpha), in gingival crevicular fluid collected from the deep (> 5 mm periodontal pocket depth) and shallow (< or = 3 mm periodontal pocket depth) periodontal pockets of 39 HIV-1-infected patients and 20 age-, race- and sex-matched uninfected controls. Complete medical history including risk factors such as intravenous drug abuse was taken. Gingival crevicular fluid samples were collected on periopaper strips. Cytokines were estimated by solid-phase enzyme-linked immunosorbent assay. To assess the degree of HIV activity, the viral load of these patients was determined by an Amplicor HIV-1 monitor kit using reverse transcriptase polymerase chain reaction. Gingival crevicular fluid from HIV-1-infected patients showed a two-fold increase in both IL-1 beta and TNF-alpha in deep periodontal pockets in comparison to shallow pockets, whereas IL-6 increased 1.8-fold. There was a significant (P < 0.05) increase in IL-1 beta, IL-6 and TNF-alpha in gingival crevicular fluid (both shallow and deep pockets) from HIV-1-infected patients in comparison to uninfected controls and also significantly elevated in deep versus shallow pockets in these patients. Although IL-1 beta, L-6 and TNF-alpha levels among HIV-1-infected patients with a high viral load (> 10,000 copies/ml) were higher than those from patients with a low viral load (< 400 copies/ml), only the increase in IL-1 beta level associated with deep pockets was significant (P < 0.05). There was also a trend of an increase in all the three cytokines among intravenous drug-abusing HIV-1-infected patients in comparison to non-intravenous drug abusers, but only the difference in IL-1 beta levels from deep pockets reached significance (P < 0.05). These enhanced pro-inflammatory cytokine levels in the gingival crevicular fluid of HIV-positive patients may be an important factor in causing the advanced periodontal lesions sometimes observed in HIV-positive patients.

HIV topic update: oro-genital transmission of HIV

Several viruses, including the human immunodeficiency virus (HIV), can be found in blood and many body fluids including saliva, and are transmissible sexually across genital and particularly anal mucosae. A persisting concern has been the question of transmission of HIV by oral sexual practices. This review discusses the evidence for oro-genital transmission of HIV, detailing the presence and infectivity of HIV in genital fluids and saliva, the case reports and epidemiology of oro-genital HIV transmission, and the evidence from animal studies. Oral intercourse is not risk-free. The evidence suggests that the risk of HIV transmission from oro-genital sexual practices is substantially lower than that from penile-vaginal or penile-anal intercourse, that exposure to saliva presents a considerably lower risk than exposure to semen, and that oral trauma and ulcerative conditions might increase the risk of HIV transmission.

The role of the oral environment in HIV-1 transmission

Human immunodeficiency virus type 1, or HIV-1, is infrequently transmitted through the mouth, unlike other mucosal sites. Factors such as low salivary viral titers, low numbers of CD4-positive target cells, anti-HIV antibodies and endogenous salivary antiviral factors work in concert to protect oral tissues from infection and reduce the risk of viral transmission through salivary secretions. This review summarizes the various factors thought to influence oral transmission HIV-1, focusing on the mucosal protein secretory leukocyte protease inhibitor, or SLPI.

HIV topic update: salivary testing for antibodies

Salivary antibody testing for HIV is proving to be a sensitive and specific procedure, especially useful for epidemiological studies, and has the advantages of being simple and non-invasive. This paper reviews the field and discusses antibody testing of dental patients.