(By Dr. Joseph D. Lim and Dr. Kenneth Lester Lim, BS-MMG, DDM, MSc-OI)
THEY ARE sprinkled like confetti, colored green, yellow, and red.
The ringed axons are nerve fibers that transmit electrical signals throughout the nervous system.
They are axons bundled in a human cranial nerve. Nerves like this exit the brainstem and project to areas of the tongue, mouth, and throat, where taste signals are detected and relayed back to the brain.
A research team led by Eva Mezey, MD, PhD, of the National Institute of Dental and Craniofacial Research (NIDCR), found that the outer surfaces of the axons in these nerves are studded with protein “entry factors” used by the SARS-CoV-2 virus to invade cells.
The presence of entry factors like TMPRSS2 proteins (yellow) and ACE2 receptors (red) points to the possibility that the virus could infect taste-sensing nerves and offers a potential explanation for the taste loss that affects about 39 percent of those who have COVID-19, said the NIDCR, a branch of the U.S. National Institutes of Health.
The NIDCR provides health information to improve the oral, dental, and craniofacial health through research. Mezey is a senior investigator at the NIDCR.
The results suggest that viruses like SARS-CoV-2 could reach the central nervous system by traveling in nerves from the mouth, Mezey says.
“The nerve terminals around the taste buds and gums could be a back door for pathogens to get into the brain,” she says.
Mezey and her research team are exploring this possibility in mice by determining whether and how certain oral bacteria can travel from the mouth to the brain.
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Dr. Joseph D. Lim, Ed. D., is the former Associate Dean of the College of Dentistry, University of the East; former Dean, College of Dentistry, National University; Past President and Honorary Fellow of the Asian Oral Implant Academy; Honorary Fellow of the Japan College of Oral Implantologists; Honorary Life Member of the Thai Association of Dental Implantology; and Founding Chairman of the Philippine College of Oral Implantologists. For questions on dental health, e-mail jdlim2008@gmail.com or text 0917-8591515.
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Dr. Kenneth Lester Lim, BS-MMG, DDM, MSc-OI, graduated Doctor of Dental Medicine, University of the Philippines, College of Dentistry, Manila, 2011; Bachelor of Science in Marketing Management, De la Salle University, Manila, 2002; and Master of Science (MSc.) in Oral Implantology, Goethe University, Frankfurt, Germany, 2019. He is an Associate Professor; Fellow, International Congress of Oral Implantologists; Member, American Academy of Implant Dentistry and Fellow, Philippine College of Oral Implantologists. For questions on dental health, e-mail limdentalcenter@gmail.com./PN
