Deleterious effect of chronic high-dose ethanol intake on biomechanical bone properties and periodontal status

To evaluate the effect of high-graduation chronic ethanol (EtOH) intake on bone and periodontal tissues of rats. Male Wistar rats (250 g) were divided into two groups of n = 12 each one. EtOH (5 ml of 3 g/kg) was administered to the experimental group by gastric gavage twice a day for 20 days and the control group received water under the same conditions. The rats were euthanized and used to perform biochemical determination in plasma and gingival tissue, and histological and biomechanical studies in the femur and mandibular tissues. Alcohol increased both TNFα (p < 0.01) and PGE2 (p < 0.05) in plasma and gingiva (p < 0.05) as compared to controls. In addition, EtOH increased the alveolar bone loss as evidenced by the increased distance between the cement enamel junction and the alveolar crest (p < 0.01), the lower % of interradicular bone expressed as bone area/total area (B.Ar/T.Ar, p < 0.05) and the larger periodontal space (p < 0.05), as compared to controls. Likewise, the mandibular microtomographic analysis in alcoholized rats revealed a lower % of interradicular bone volume/total volume (BV/TV, p < 0.05), greater trabecular separation (p < 0.05) and greater % trabecular porosity (p < 0.05) than controls. No biomechanical alteration was observed in lower jaws, while the femur of alcoholized rats presented a decrease in the structural bone properties (p < 0.001), as a systemic consequence of deterioration of the diaphyseal architecture (p < 0.01) without changes in material properties. The consumption of high doses of alcohol produces deleterious effects on periodontal tissues that could be due not only to local but also systemic effects.

Analysis of Neisseria lactamica antigens putatively implicated in acquisition of natural immunity to Neisseria meningitidis

Sera from healthy human volunteers, patients convalescent from meningococcal meningitis, and mice immunized with outer membrane proteins from Neisseria meningitidis and Neisseria lactamica strains were used to analyze and identify antigens cross-reactive to both neisserial species. All classes of meningococcal proteins except class 1 (PorA) and class 5 cross-reacted with N. lactamica proteins and two other proteins of 65 and 55 kDa (an iron-regulated protein). Results obtained with the mouse sera demonstrate that cross-reactive antibodies can be elicited by either N. meningitidis or N. lactamica. These results support the suggestion that N. lactamica contributes to the development of natural immunity against N. meningitidis during the first years of life. The use of vaccines containing proteins other than PorA could interfere in colonization of mucosal surfaces by N. lactamica, hampering the natural mechanisms of immunity acquisition in humans. Only convalescent sera reacted with the 55 and 65 kDa proteins, which suggests that they might be relevant for pathogenicity.

In vitro induction of memory-driven responses against Neisseria meningitidis by priming with Neisseria lactamica

Natural immunity against Neisseria meningitidis is acquired during childhood and youth through successive colonizations by commensal Neisseria, carrier N. meningitidis, and other bacterial genera sharing cross-reactive antigens with the meningococci. We have analyzed in mice the ability of Neisseria lactamica strains to induce immunological memory so that, upon a later contact with N. meningitidis, quickly raise protective responses against antigens that show cross-reactivity with meningococcal surface proteins. Sera obtained from mice immunized with N. lactamica and boosted with N. meningitidis were able to kill meningococci, with bactericidal activities variable depending on the immunizing strains used in the assays. Different mixtures of those sera resulted in higher killing activities, which agrees with the idea that successive colonizations by N. lactamica enhance the anti-meningococcal response. The existence of such outer membrane cross-reactive antigens has to be kept in mind when using outer membrane vesicle (OMV)-based anti-meningococcal vaccines because their use can affect colonization by N. lactamica and other species, hampering the natural mechanisms of acquisition of immunity to the meningococci, and leaving its ecological niche free for colonization by undesirable microorganisms.

Evaluation of cross-reactive antigens as determinants of cross-bactericidal activity in pathogenic and commensal Neisseria

Several antisera raised against outer membane vesicles obtained from invasive and carrier Neisseria meningitidis strains and commensal Neisseria and Moraxella catharralis species were assayed to test cross-bactericidal activity on Neisseria meningitidis strains. Results demonstrate that, despite the wide antigenic cross-reactivity previously shown by Western-blotting for the major outer membrane antigenic proteins of all Neisseria species, complement mediated killing shows very variable patterns that can not be predicted on the basis of antigenic cross-reactivity. Results of antibody tritations on homologous and heterologous strains, isotyping, and bactericidal activity of sera raised against denatured purified outer-membrane vesicle proteins, suggest that the responsibility for most of the bactericidal activity of the sera must be conformational and/or shared epitopes not detectable by Western-blotting.

Analysis of the expression of the putatively virulence-associated neisserial protein RmpM (class 4) in commensal Neisseria and Moraxella catarrhalis strains

The RmpM protein has been reported to be present only in pathogenic Neisseria species. In the present study we demonstrate that this protein is also present at least in N. lactamica and N. sicca strains. The N. lactamica protein reacts with a RmpM-specific monoclonal antibody (185,H-8), having a molecular mass ( approximately 31 kDa) slightly lower than that of the meningococcal RmpM, and mouse antibodies from sera against outer membrane vesicles from both N. lactamica and N. sicca strains cross-react with the meningococcal RmpM. PCR and hybridization experiments with a complete rmpM probe agree with the immunodetection experiments. Our results strongly suggest that the meningococcal RmpM should not be considered a virulence marker, and the presence of this protein in the commensal species agrees with its role as a structural protein, proposed for the RmpM, which should be considerably conserved in the Neisseria species.

Antigenic cross-reactivity between outer membrane proteins of Neisseria meningitidis and commensal Neisseria species

Two mouse sera against outer membrane proteins from a pathogenic Neisseria meningitidis strain and a commensal N. lactamica strain and two human sera from patients recovering from meningococcal meningitis were used to identify antigens common to pathogenic and commensal Neisseria species. Two major antigens of 55 kDa and 32 kDa, present in all N. meningitidis and N. lactamica strains tested, were demonstrable with all the sera used; the 55-kDa protein was iron-regulated. Demonstration of other common antigens was dependent on the serum used: a 65-kDa antigen was visualised with the human and the mouse anti-N. lactamica sera; a 37-kDa antigen identified as the meningococcal ferric binding protein (FbpA) was only detected with the mouse sera, and two antigens of 83 kDa and 15 kDa were only shown with the mouse anti-N. meningitidis serum. The results demonstrate the existence of several outer membrane antigens common to N. lactamica and N. meningitidis strains, in agreement with the hypothesis that natural immunity against meningitis is partially acquired through colonisation by commensal species, and open new perspectives for the design of vaccine formulations and the development of strategies for vaccination against meningitis.