Human salivary agglutinin binds to lung surfactant protein-D and is identical with scavenger receptor protein gp-340.

Salivary agglutinin is a 300-400 kDa salivary glycoprotein that binds to antigen B polypeptides of oral streptococci, thereby playing a role in their colonization and the development of caries. A mass spectrum was recorded of a trypsin digest of agglutinin. A dominant peak of 1460 Da was sequenced by quadrupole time-of-flight (Q-TOF) tandem MS. The sequence showed 100% identity with part of the scavenger receptor cysteine-rich ('SRCR') domain found in gp-340/DMBT1 (deleted in malignant brain tumours-1). The mass spectrum revealed 11 peaks with an identical mass as a computer-simulated trypsin digest of gp-340. gp-340 is a 340 kDa glycoprotein isolated from bronchoalveolar lavage fluid that binds specifically to lung surfactant protein-D. DMBT1 is a candidate tumour suppressor gene. A search in the human genome revealed only one copy of this gene. The molecular mass, as judged from SDS/PAGE and the amino acid composition of agglutinin, was found to be nearly identical with that of gp-340. It was shown by Western blotting that monoclonal antibodies against gp-340 reacted with salivary agglutinin, and monoclonals against agglutinin reacted with gp-340. It was demonstrated that gp-340 and agglutinin bound in a similar way to Streptococcus mutans and surfactant protein-D. Histochemically, the distribution of gp-340 in the submandibular salivary glands was identical with the agglutinin distribution, as shown in a previous paper [Takano, Bogert, Malamud, Lally and Hand (1991) Anat. Rec. 230, 307-318]. We conclude that agglutinin is identical with gp-340, and that this molecule interacts with S. mutans and surfactant protein-D.

Salivary MUC5B-mediated adherence (ex vivo) of Helicobacter pylori during acute stress.

OBJECTIVE: Biochemical host defenses at mucosal sites, such as the oral cavity, play a key role in the regulation of microbial ecology and the prevention of infectious disease. These biochemical factors have distinct features, some of which benefit the host and some that benefit bacteria. We investigated the effects of acute stress on the salivary levels of the carbohydrate structure sulfo-Lewis (sulfo-Le), which is linked to the mucosal glycoprotein MUC5B. Sulfo-Le was recently identified as an adhesion molecule for Helicobacter pylori; therefore, we also measured saliva-mediated adherence (ex vivo) of H. pylori. The oral cavity is suspected to be involved in the transmission of H. pylori. METHODS: Saliva was collected from 17 undergraduates before (baseline), during (stress), and after (recovery) exposure to a video showing surgical procedures. In addition, blood pressure, an impedance cardiogram, and an electrocardiogram were recorded. RESULTS: During stressor exposure, participants reported increased state anxiety. In addition, stroke volume increased and heart rate decreased. The stressor induced a strong increase in salivary sulfo-Le concentration (U/ml), sulfo-Le output (U/min), sulfo-Le/total protein ratio (U/mg protein), and saliva-mediated adherence (ex vivo) of H. pylori. As expected, sulfo-Le concentration correlated with the adherence of H. pylori (r = 0.72, p < .05). It was demonstrated that the observed adherence was induced by MUC5B and that the carbohydrate structure sulfo-Le contributed to this process. CONCLUSIONS: Our study demonstrated a direct link between stress-mediated biochemical changes and altered host-microbe interactions in humans. Increased bacterial adherence may be a contributing factor in the observed relationship between stress and susceptibility to infectious disease.

Psychological stress as a determinant of protein levels and salivary-induced aggregation of Streptococcus gordonii in human whole saliva.

Several pathologies of the oral cavity have been associated with stress, so we investigated salivary-induced aggregation during psychological stress. In addition, salivary total protein, alpha-amylase, and secretory immunoglobulin A (s-IgA) were assessed. In this longitudinal study, 28 dental students provided unstimulated whole saliva during 10 minutes before an academic examination and subsequently 2 weeks and 6 weeks later in a nonstress situation. The effect of whole saliva on the aggregation of Streptococcus gordonii (HG 222) was determined spectrophotometrically. The results shows a significant stress-mediated increase of salivary total protein concentration, alpha-amylase activity, amylase/protein ratio, alpha-amylase output, s-IgA concentration, and s-IgA output. There was also a trend for increased total protein output, whereas salivary flow rate was unchanged. The aggregation of S. gordonii in whole saliva collected before examination was 13.1%, whereas the aggregation in whole saliva collected during nonstress was 23.3%. This reduction was statistically significant (p < .01). Furthermore, the decrease in bacterial aggregation was related to the increase in state-anxiety (p < .05). The reduction in aggregation of S. gordonii under stress was not correlated with changes in salivary flow rate, s-IgA concentration, total protein concentration, or alpha-amylase activity. These results suggest that acute psychological stress exerts its influence on both salivary composition and salivary function. Reduced bacterial aggregation may be a contributing factor in the often reported relationship between stress and impaired oral health.