Effect of blood group determinants on binding of human salivary mucous glycoproteins to influenza virus

Association of ABO blood group with respiratory disease hospitalization and severe outcomes: a retrospective cohort study in blood donors

OBJECTIVES

Environmental, socioeconomic, and genetic factors all are associated with respiratory diseases. We aimed to investigate the association between the ABO blood group and the susceptibility to respiratory diseases.

METHODS

We constructed a retrospective cohort study of blood donors in Shaanxi, China between January 1, 2012, and December 31, 2018, to investigate the impacts of the ABO blood group on the risk of hospitalization due to respiratory diseases.

RESULTS

Of 1,686,263 enrolled participants (680,788 females), 26,597 were admitted to the hospital for respiratory diseases. Compared with blood group O, blood groups A, B, and AB all demonstrated a higher risk for diseases of the upper respiratory tract (International Classification of Diseases, Tenth Revision: J30-J39) (ARR (Adjusted relative risk) 1.139, 95% confidence interval [1.106-1.225]; 1.095 [1.019-1.177]; 1.178 [1.067-1.30], respectively). Conversely, blood group A was found to have a lower risk (0.86 [0.747-0.991]) for influenza (J09-J11) and blood group B had a lower risk for pneumonia (J12-J18) (0.911 [0.851-0.976]) than blood group O. The duration of hospitalization was significantly different across the blood groups in J09-J11 and J30-J39 (P <0.05).

CONCLUSION

The blood group appears to be a prognostic factor in differentiating the occurrence of specific respiratory diseases and duration.

Bacterial neuraminidase rescues influenza virus replication from inhibition by a neuraminidase inhibitor

Influenza virus neuraminidase (NA) cleaves terminal sialic acid residues on oligosaccharide chains that are receptors for virus binding, thus playing an important role in the release of virions from infected cells to promote the spread of cell-to-cell infection. In addition, NA plays a role at the initial stage of viral infection in the respiratory tract by degrading hemagglutination inhibitors in body fluid which competitively inhibit receptor binding of the virus. Current first line anti-influenza drugs are viral NA-specific inhibitors, which do not inhibit bacterial neuraminidases. Since neuraminidase producing bacteria have been isolated from oral and upper respiratory commensal bacterial flora, we posited that bacterial neuraminidases could decrease the antiviral effectiveness of NA inhibitor drugs in respiratory organs when viral NA is inhibited. Using in vitro models of infection, we aimed to clarify the effects of bacterial neuraminidases on influenza virus infection in the presence of the NA inhibitor drug zanamivir. We found that zanamivir reduced progeny virus yield to less than 2% of that in its absence, however the yield was restored almost entirely by the exogenous addition of bacterial neuraminidase from Streptococcus pneumoniae. Furthermore, cell-to-cell infection was severely inhibited by zanamivir but restored by the addition of bacterial neuraminidase. Next we examined the effects of bacterial neuraminidase on hemagglutination inhibition and infectivity neutralization activities of human saliva in the presence of zanamivir. We found that the drug enhanced both inhibitory activities of saliva, while the addition of bacterial neuraminidase diminished this enhancement. Altogether, our results showed that bacterial neuraminidases functioned as the predominant NA when viral NA was inhibited to promote the spread of infection and to inactivate the neutralization activity of saliva. We propose that neuraminidase from bacterial flora in patients may reduce the efficacy of NA inhibitor drugs during influenza virus infection. (295 words).

alpha-Galactosidase activity in human saliva

OBJECTIVE

The purpose of this study was to investigate whether alpha-galactosidase activity is present in whole and glandular saliva and whether alpha-galactosidase activity depends on blood type and secretor status.

DESIGN

For the first experiments, 30 healthy participants (15 men, 15 women; mean age, 24.2+/-1.5 years) who were 10 A, 10 B, and 10 O blood type subjects were included. alpha-Galactosidase activity in unstimulated whole saliva (UWS) was assayed by using 4-methylumbelliferyl-alpha-d-galactopyranoside as a substrate. Total protein concentration was determined by bicinchoninic acid assay. The secretor status of the blood group antigens was determined by immunoblotting. alpha-Galactosidase activity in UWS according to gender, blood type, secretor status, sample clarification, and buffer was investigated. Daily variations of alpha-galactosidase activity and alpha-galactosidase isozyme activity were also investigated. For the second experiments, 10 healthy blood type B participants (5 men, 5 women; mean age, 27.0+/-2.7 years) were enrolled. alpha-Galactosidase activity in whole and glandular saliva was investigated.

RESULTS

alpha-Galactosidase activity was detected in UWS and was mainly isozyme A activity. There was no difference in alpha-galactosidase activity according to gender, blood type, and secretor status. alpha-Galactosidase activity in UWS was higher in unclarified samples than in clarified ones and showed wide daily variations. alpha-Galactosidase activity in whole saliva was significantly higher than that in glandular saliva.

CONCLUSIONS

alpha-Galactosidase activity which is mainly isozyme A activity was detected in human whole and glandular saliva. alpha-Galactosidase activity in UWS did not differ according to blood type and secretor status.

Human-Milk Glycans That Inhibit Pathogen Binding Protect Breast-feeding Infants against Infectious Diarrhea

Breast-feeding is a highly effective strategy for preventing morbidity and mortality in infancy. The human-milk glycans, which include oligosaccharides in their free and conjugated forms, constitute a major and an innate immunologic mechanism by which human milk protects breast-fed infants against infections. The glycans found in human milk function as soluble receptors that inhibit pathogens from adhering to their target receptors on the mucosal surface of the host gastrointestinal tract. The alpha1,2-linked fucosylated glycans, which require the secretor gene for expression in human milk, are the dominant glycan structure found in the milk of secretor mothers, who constitute the majority ( approximately 80%) of mothers worldwide. In vitro and in vivo binding studies have demonstrated that alpha1,2-linked fucosylated glycans inhibit binding by campylobacter, stable toxin of enterotoxigenic Escherichia coli, and major strains of caliciviruses to their target host cell receptors. Consistent with these findings, recently published epidemiologic data demonstrate that higher relative concentrations of alpha1,2-linked fucosylated glycans in human milk are associated with protection of breast-fed infants against diarrhea caused by campylobacter, caliciviruses, and stable toxin of enterotoxigenic E. coli, and moderate-to-severe diarrhea of all causes. These novel data open the potential for translational research to develop the human-milk glycans as a new class of antimicrobial agents that prevent infection by acting as pathogen anti-adhesion agents.

Human milk oligosaccharides are associated with protection against diarrhea in breast-fed infants

OBJECTIVE

To determine the association between maternal milk levels of 2-linked fucosylated oligosaccharide and prevention of diarrhea as a result of Campylobacter, caliciviruses, and diarrhea of all causes in breast-fed infants.

STUDY DESIGN

Data and banked samples were analyzed from 93 breast-feeding mother-infant pairs who were prospectively studied during 1988-1991 from birth to 2 years with infant feeding and diarrhea data collected weekly; diarrhea was diagnosed by a study physician. Milk samples obtained 1 to 5 weeks postpartum were analyzed for oligosaccharide content. Data were analyzed by Poisson regression.

RESULTS

Total 2-linked fucosyloligosaccharide in maternal milk ranged from 0.8 to 20.8 mmol/L (50%-92% of milk oligosaccharide). Moderate-to-severe diarrhea of all causes (n=77 cases) occurred less often (P=.001) in infants whose milk contained high levels of total 2-linked fucosyloligosaccharide as a percent of milk oligosaccharide. Campylobacter diarrhea (n=31 cases) occurred less often (P=.004) in infants whose mother's milk contained high levels of 2'-FL, a specific 2-linked fucosyloligosaccharide, and calicivirus diarrhea (n=16 cases) occurred less often (P=.012) in infants whose mother's milk contained high levels of lacto-N-difucohexaose (LDFH-I), another 2-linked fucosyloligosaccharide.

CONCLUSION

This study provides novel evidence suggesting that human milk oligosaccharides are clinically relevant to protection against infant diarrhea.

Attachment of influenza A virus to ferret tracheal epithelium at different maturational stages

Influenza virus attaches primarily to ciliated cells in mature airways epithelium. This process is mediated by a viral envelope glycoprotein (hemagglutinin) that binds to sialic acid-containing receptors in the apical membrane of host cells. The purpose of this study was to determine the cellular distribution of these receptors as a function of tracheal epithelial maturation in the ferret, which is susceptible to influenza virus infection at all ages and undergoes postnatal ciliation. To assay for virus attachment, tracheal strips from ferrets at ages 0, 7, 14, and 28 d were incubated at 4 degrees C for 1 h with a concentrated suspension of influenza A virus. Transmission electron microscopy demonstrated virus attachment to the apical surface of 77 to 87% of ciliated cells, but only to 1 to 9% of nonciliated surface epithelial cells at all ages, including the newborn, which has few ciliated cells (less than 10% of total cells). Virions also attached to most of the preciliated cells identified. Pretreatment of tracheal strips with neuraminidase virtually eliminated viral attachment. These findings demonstrate preferential influenza virus binding to sialylated receptors on ciliated cells and their immediate precursors. The sparsity of ciliated cells with no evidence for increased influenza virus binding per cell in newborn ferret tracheas suggests that the previously demonstrated high risk of death from influenza infection in newborn ferrets is due to factors other than increased susceptibility to virus attachment. Influenza virus receptors appear to be selective membrane markers for ciliated cells and may be particularly useful for the identification of preciliated cells.

ABO blood group, secretor state, and susceptibility to recurrent urinary tract infection in women

ABO blood group and secretor state was determined in 319 women with recurrent urinary tract infection and compared with those of a control group of 334 women of similar age ranges. Women of blood groups B and AB who are non-secretors of blood group substances showed a significant relative risk of recurrent urinary tract infection of 3.12 (95% confidence limits, 1.49 and 6.52) in comparison with other types. This appears to be a genuine example of synergy in which absence of anti-B isohaemagglutinin and secretor substances combines to give an increased risk of recurrent urinary tract infection. Determination of blood group and secretor state may provide additional information in identifying those at risk.

Role of salivary mucins in the protection of the oral cavity

Mucins are the principal organic constituents of mucus, the slimy visco-elastic material that coats all mucosal surfaces. Compelling evidence suggests that they play an integral role in non-immune protection of the oral cavity. Specific protective functions include: 1) protection against desiccation and environmental insult, 2) lubrication, and 3) antimicrobial effects against potential pathogens. Biosynthesis of mucin is regulated by both intrinsic ("cooperative sequential specificity") and extrinsic ("structural modulation") controls. These controls form the basis by which mucin's structure can be modified to meet a dynamically changing biological need.