Otsuka Pharmaceutical Co., Ltd.

June 7, 2022

Otsuka Pharmaceutical Publishes Paper Investigating Binding Property of Salivary IgA on Pathogenic Microorganisms

The Otsu Nutraceuticals Research Institute of Otsuka Pharmaceutical Co., Ltd. is engaged in research focusing on mucosal immunity, the ability of mucosal surfaces in contact with the external environment to inhibit the invasion of foreign substances into the body. Immunoglobulin A (IgA)*1 is a secretory antibody that plays an important role in mucosal immunity. A research paper investigating the pathogenic microorganisms bound by salivary IgA was accepted by Bioscience of Microbiota, Food and Health, the joint journal of The Intestinal Microbiology Society, the Japan Society for Lactic Acid Bacteria, and the Japanese Association for Food Immunology. Submitted by the Otsu Nutraceuticals Research Institute, the paper received advance publication on the J-STAGE*2 platform on June 6, 2022.

Indicating the potential of salivary IgA to inhibit infection from a variety of pathogenic microorganisms, results of the study suggest that enhancement of salivary IgA secretion may be an important factor in prevention of infection.

In addition to clarification of the significance of enhancing secretion of salivary IgA, the study expands the possibility that components that enhance IgA secretion can contribute to better health and opens the way for further research into the value of IgA and mucosal immunity.

Details of Publication

Title: Identification of antigens recognized by salivary IgA using microbial protein microarrays

Authors: Koji Hamuro, Hiroshi Saito, Takao Saito and Noriyuki Kohda

Journal: Bioscience of Microbiota, Food and Health

Outline of Study

Background and objectives

Secretory IgA, which is secreted at mucosal surfaces, plays an important role in the mucosal immune system for protection against pathogens. However, little information was available about the types of microorganisms recognized by secretory IgA or how increases and decreases in the amount of IgA might affect biological defenses. This led to a comprehensive study to identify the pathogenic microorganisms to which secretory IgA binds.

Methods Saliva samples from 12 adult subjects were profiled using microbial protein microarrays*3.

It has been clarified that saliva contains IgA which binds with various pathogenic microorganisms that can infect mucosal tissue in the respiratory and digestive systems.

Viruses bound by salivary IgA included coronaviruses such as SARS-CoV-2, influenza virus, herpes simplex virus, human papillomavirus, as well as viruses for which subjects had little or no previous exposure, such as dengue virus, Zika virus and ebolavirus.

Regarding influenza viruses, binding was confirmed for a large number of subtypes and strains in addition to historically prevalent strains and those included in influenza vaccines. For bacteria, in addition to Streptococcus pneumoniae and Mycobacterium tuberculosis, which typically infect the respiratory tract and Helicobacter pylori, which infects the stomach, intestinal bacteria related to food poisoning such as pathogenic Escherichia coli, Salmonella enterica and Clostridium perfringens were also bound by salivary IgA. It was confirmed that salivary IgA binds to many types of E. coli and Salmonella enterica species.
Discussion The present study shows the broad cross-reactivity of salivary IgA, indicating the potential of the mucosal immune system at the forefront of defense, inhibiting various pathogenic microorganisms. This suggests that increasing salivary IgA may be important for prevention of infection.

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  1. *1A type of antibody; in addition to IgA, antibodies include IgG, IgM, IgE. In the mucosal surfaces, IgA plays a major role in preventing the invasion of foreign substances.
  2. *2J-STAGE (Japan Science Technology Information Aggregator, Electronic) is an electronic journal platform for academic journals in Japan, developed and managed by the Japan Science and Technology Agency. Bioscience of Microbiota, Food and Health and many other journals are published on J-STAGE.
  3. *3A general term for instruments or techniques that permit simultaneous analysis of large numbers of analytes that have been immobilized on a substrate. In addition to proteins, microarrays can be created for DNA, cellular materials, tissues and chemical compounds.

【Otsuka Pharmaceutical Co., Ltd. Otsu Nutraceuticals Research Institute】

Established in 2000, the Otsu Nutraceuticals Research Institute is dedicated to research concerning the intestines and nutrition. Focusing on the intestines where nutrition is absorbed, mucosal immunity is the theme of research to identify functions of lactic acid bacteria and develop related products.

Screening of lactic acid bacteria to enhance secretion of IgA, which prevents the invasion of foreign substances in mucosal surfaces of mouth, throat and nose, began in 2003. Effects of plant-derived Lactiplantibacillus pentosus ONRICb0240 (lactic acid bacterium ONRICb0240), isolated by Tokyo University of Agriculture, to enhance secretion of IgA were initially discovered in 2005, and research to enhance the functions of mucosal immunity continues at the Otsu Nutraceuticals Research Institute.