Effect of bleaching agent extracts on murine macrophages.

OBJECTIVES: The aim of this study was to evaluate the cytotoxicity and the influence of bleaching agents on immunologically cell surface antigens of murine macrophages in vitro. MATERIALS AND METHODS: RAW 264.7 cells were exposed to bleaching gel extracts (40% hydrogen peroxide or 20% carbamide peroxide) and different H2O2 concentrations after 1 and 24-h exposure periods and 1-h exposure and 23-h recovery. Tests were performed with and without N-acetyl cysteine (NAC) and buthionine sulfoximine (BSO). Cell viability was determined by MTT assay. The expression of surface markers CD14, CD40, and CD54 with and without LPS stimulation was detected by flow cytometry, while the production of TNF-α was measured by ELISA. Statistical analysis was performed using the Mann-Whitney U test (α = 0.05). RESULTS: Extracts of bleaching agents were cytotoxic for cells after a 1-h exposure; cells could not recover after 24 h. This effect can be mitigated by the antioxidant NAC and increased by BSO, an inhibitor of glutathione (GSH) synthesis. LPS stimulated expression of all surface markers and TNF-α production. Exposure to bleaching agent extracts and H2O2 leads to a reduction of TNF-α, CD14, and CD40 expression, while the expression of CD54 was upregulated at non-cytotoxic concentrations. Whereas NAC reduced this effect, it was increased in the presence of BSO. CONCLUSIONS: Extracts of bleaching agents were irreversibly cytotoxic to macrophages after a 1-h exposure. Only the expression of CD54 was upregulated. The reactions are mediated by the non-enzymatic antioxidant GSH. CLINICAL RELEVANCE: The addition of an antioxidant can downregulate unfavorable effects of dental bleaching.

Schistosomes--proteomics studies for potential novel vaccines and drug targets.

Schistosomiasis is a major health problem and, despite decades of research, only one effective drug, Praziquantel is currently available. Recent expansion of sequence databases on Schistosoma mansoni and S. japonicum has permitted a wealth of novel proteomic studies on several aspects of the organization and development of the parasite in the human host. This unprecedented accumulation of molecular data is allowing a more rational approach to propose drug targets and vaccine candidates, such as proteins located at the parasite surface. Successful preliminary trials of two vaccine candidates that have been detected at the parasite surface by proteomics give grounds for believing that such an approach may provide a fresh start for the field.

Interleukin-2 induces peroxide production by primed normodense eosinophils of patients with asthma.

In this study we assessed, by flow cytometry, the effect of interleukin 2 (IL-2) on the oxidative burst of normodense eosinophils (Eos's) isolated from 15 patients with moderately severe extrinsic asthma and 17 controls. We found that IL-2 significantly induced peroxide (H2O2) production in normodense Eos's from patients with asthma on a time kinetics study. This rise was higher in patients with immunoglobulin E levels > 180 IU/mL versus normal immunoglobulin E values. The effect of IL-2 was partially blocked by using anti-Tac antibody. In contrast, IL-2 decreased H2O2 production in normodense Eos's from controls. Cell surface expression of CD25, CD122, CD132, and CD69 were also determined and no statistical differences were found between both groups. In conclusion, IL-2 is able to increase H2O2 production by normodense Eos's isolated from patients with asthma and it may contribute to bronchial epithelium damage and chronic inflammation.

[Leishmania major lipophosphoglycan modulates the expression of receptors involved in parasite internalization in skin Langerhans cells]. / El lipofosfoglicano de Leishmania major modula la expresion de receptores involucrados en la internalización del parasito en celulas de Langerhans de la piel.

Despite the immunological changes recognized to be produced during Leishmania infection and the central role played by Langerhans cells, it is not known whether Leishmaina lipophosphoglycan, the most abundant glycolipid on the parasite surface, affects the functions of Langerhans cells. Here, we provide evidence that exposure of Langerhans cells to Leishmaina (L.) major lipophosphoglycan has consequences for the expression of surface receptors. Down-regulation of receptors involved in host cell-parasite interaction are observed after 4 h exposure of Langerhans cells to lipophosphoglycan. Many of the changes are also induced in Langerhans cells incubated with L. major-conditioned medium, indicating that the observed effects may be mediated by soluble factors released by the parasite into the culture, as it is the case for the carbohydrate moiety of lipophosphoglycan. Taken together, these results indicate that the changes in surface molecule expression induced by the exposure of Langerhans cells to lipophosphoglycan might reflect changes in their signalling functions from the infected skin.

Effect of gangliosides in the autoimmune response induced by liposome-associated antigens.

A model of autoimmunity to rat male accessory glands (RAG) was recently developed by intraperitoneal administration of three doses of native RAG associated with liposomes. In this work we analysed the effects of gangliosides in the cellular response to RAG when they were intraperitoneally administrated prior to the second dose of liposome-associated RAG. Results show that the ganglioside treatment could modify an established DTH response. Also, gangliosides markedly reduced the number of Ia antigen-positive peritoneal exudated cells (PEC). However, they modified neither the processing of liposomes through PEC nor their viability. Moreover, we obtained cellular response by transferring PEC from immunized donors into naive receptors.