Periodontitis is a chronic inflammatory disease of the soft and hard supporting tissues of the teeth and is a major cause of tooth loss in adults. The local host response to periodontopathic bacteria results in the release of inflammatory mediators and cytokines. Since cytokines are indicative of effector functions, we compared the pattern of cytokine production in periodontal patients and healthy controls. Specifically, we investigated the simultaneous presence of cytokines produced by T helper (Th)l, Th 2, and inflammatory cells which could be involved in periodontitis. We also compared the expression of these cytokine mRNAs in healthy and diseased tissues. No significant differences were detected at the protein or mRNA levels of the cytokines in the systemic circulation of patients and controls. The surface markers CD 16 and CD56 were expressed on significantly fewer peripheral mononuclear cells of patients when compared to controls. γδ+ T cells were found in half of the diseased tissues, but in none of the healthy tissues of either patients or controls. Finally, significant differences were observed between healthy and inflamed gingival tissues in the cytokine mRNA profile. Expression of IL‐6 and IFN‐α mRNA was significantly higher in diseased tissues compared to healthy tissues in patients. J Periodontol 1996;67:515–522.

Wear debris from orthopedic joint implants have been postulated to initiate a cascade of complex cellular events that results in aseptic loosening of the prosthesis and eventually in loss of function of the device. The impact of biomaterials used in these devices on host inflammatory response has not been examined extensively. Polymethylmethacrylate (PMMA) and cobalt-chrome alloy (CoCr) are biomaterials widely used in orthopedic implant devices. Macrophages are an important component of the host inflammatory response, and we have examined the effect of PMMA and CoCr particles on the murine macrophage cell line J774A.1. Our objective was to obtain a comprehensive analysis of the particle-macrophage interaction, and we examined a number of basic biological responses of the J774A.1 cell line, including cell proliferation, apoptosis, cytokines secreted into the culture supernatant (TNF␣, IL-1␣, IL-6, and IL-12) and mRNA expression of the cytokines (TNF␣, IL-1␣, IL-6, IFN-␣, M-CSF, and TGF-␤) in response to PMMA and CoCr particles. Our results indicate that the relative contribution of PMMA and CoCr particles in J774A.1 activation is negligible, and we observed a change in metabolic activity of J774A.1 cells only at higher concentrations of CoCr particles.

Expression of the mouse immunoglobulin locus is regulated by the intron and 3 enhancers. Previously, we have reported that these enhancers can synergize at mature B cell stages. Here we present our recent studies on the identification and characterization of the 3 enhancer sequences that play important roles in this synergy. By performing mutational analyses with novel reporter constructs, we find that the 5 region of the cAMP response element (CRE), the PU.1/PIP, and the E2A motifs of the 3 enhancer are critical for the synergy. These motifs are known to contribute to the enhancer activity. However, we also show that mutating other functionally important sequences has no significant effect on the synergy. Those sequences include the 3 region of the CRE motif, the BSAP motif, and the region 3 of the E2A motif. We have further demonstrated that either the 5-CRE, the PU.1/PIP, or the E2A motif alone is sufficient to synergize with the intron enhancer. Moreover, the PU.1 motif appears to act as a negative element at pre-B cell stages but as a positive element at mature B cell stages. We have also identified a novel negative regulatory sequence within the 3 enhancer that contributes to the regulation of synergy, as well as developmental stage and tissue specificity of expression. While the levels of many of the 3 enhancer binding factors change very little in cell lines representing different B cell stages, the intron enhancer binding factors significantly increase at more mature B cell stages.

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