How does the immune system fight pathogens?
The immune system has two distinct components: mucosal and circulatory.
The mucosal immune system provides protection at the mucosal surfaces of the body. These include the mouth, eyes, middle ear, the mammary and other glands, and the gastrointestinal, respiratory, and urogenital tracts. Antibodies and a variety of other anti-microbial proteins in the sticky secretions that cover these surfaces, as well as immune cells located in the lining of these surfaces, directly attack invading pathogens.
What are the key players in mucosal immunity?
The immune components people may be most familiar with are proteins known as antibodies, or immunoglobulins. The immune system generates antibodies in response to invading agents that the body identifies as “non-self,” such as viruses and bacteria.
Antibodies bind to specific antigens: the part or product of a pathogen that induces an immune response. Binding to antigens allows antibodies to either inactivate them, as they do with toxins and viruses, or kill bacteria with the help of additional immune proteins or cells.
The mucosal immune system generates a specialized form of antibody called secretory IgA, or SIgA. Because SIgA is located in mucosal secretions, such as saliva, tears, nasal and intestinal secretions, and breast milk, it is resistant to digestive enzymes that readily destroy other forms of antibodies. It is also superior to most other immunoglobulins at neutralizing viruses and toxins, and at preventing bacteria from attaching to and invading the cells lining the surfaces of organs.
There are also many other key players in the mucosal immune system, including different types of anti-microbial proteins that kill pathogens, as well as immune cells that generate antibody responses.
How does the COVID-19 virus enter the body?
Almost all infectious diseases in people and other animals are acquired through mucosal surfaces, such as by eating or drinking, breathing or sexual contact. Major exceptions include infections from wounds, or pathogens delivered by insect or tick bites.
The virus that causes COVID-19, SARS-CoV-2, enters the body via droplets or aerosols that get into your nose, mouth, or eyes. It can cause severe disease if it descends deep into the lungs and causes an overactive, inflammatory immune response.
This means that the virus’s first contact with the immune system is probably through the surfaces of the nose, mouth, and throat. This is supported by the presence of SIgA antibodies against SARS-CoV-2 in the secretions of infected people, including their saliva, nasal fluid, and tears. These locations, especially the tonsils, have specialized areas that specifically trigger mucosal immune responses.
Some research suggests that if these SIgA antibody responses form as a result of vaccination or prior infection, or occur quickly enough in response to a new infection, they could prevent serious disease by confining the virus to the upper respiratory tract until it is eliminated.
How do nasal vaccines work?
Vaccines can be given through mucosal routes via the mouth or nose. This induces an immune response through areas that stimulate the mucosal immune system, leading mucosal secretions to produce SIgA antibodies.
There are several existing mucosal vaccines, most of them taken by mouth. Currently, only one, the flu vaccine, is delivered nasally.
In the case of nasal vaccines, the viral antigens intended to stimulate the immune system would be taken up by immune cells within the lining of the nose or tonsils. While the exact mechanisms by which nasal vaccines work in people have not been thoroughly studied, researchers believe they work analogously to oral mucosal vaccines. Antigens in the vaccine induce B cells in mucosal sites to mature into plasma cells that secrete a form of IgA. That IgA is then transported into mucosal secretions throughout the body, where it becomes SIgA.
If the SIgA antibodies in the nose, mouth or throat target SARS-CoV-2, they could neutralize the virus before it can drop down into the lungs and establish an infection.
What advantage do mucosal vaccines have against COVID-19?
I believe that arguably the best way to protect an individual against COVID-19 is to block the virus at its point of entry, or at least to confine it to the upper respiratory tract, where it might inflict relatively little damage.
Breaking chains of viral transmission is crucial to controlling epidemics. Researchers know that COVID-19 spreads during normal breathing and speech, and is exacerbated by sneezing, coughing, shouting, singing and other forms of exertion. Because these emissions mostly originate from saliva and nasal secretions, where the predominant form of antibody present is SIgA, it stands to reason that secretions with a sufficiently high level of SIgA antibodies against the virus could neutralize and thereby diminish its transmissibility.
Existing vaccines, however, do not induce SIgA antibody responses. Injected vaccines primarily induce circulating IgG antibodies, which are effective in preventing serious disease in the lungs. Nasal vaccines specifically induce SIgA antibodies in nasal and salivary secretions, where the virus is initially acquired, and can more effectively prevent transmission.
Nasal vaccines may be a useful supplement to injected vaccines in hot spots of infection. Since they don’t require needles, they might also help overcome vaccine hesitancy due to fear of injections.
How close are researchers to creating a nasal COVID-19 vaccine?
There have been over 100 oral or nasal COVID-19 vaccines in development around the world.
Most of these have been or are currently being tested in animal models. Many have reported successfully inducing protective antibodies in the blood and secretions, and have prevented infection in these animals. However, few have been successfully tested in people. Many have been abandoned without fully reporting study details.
According to the World Health Organization, 14 nasal COVID-19 vaccines are in clinical trials as of late 2022. Reports from China and India indicate that nasal or inhaled vaccines have been approved in these countries. But little information is publicly available about the results of the studies supporting approval of these vaccines.
Cancer and AI – Can ChatGPT Be Trusted?
A study published in the Journal of The National Cancer Institute Cancer Spectrum delved into the increasing use of chatbots and artificial intelligence (AI) in providing cancer-related information. The researchers discovered that these digital resources accurately [...]
Breathing New Life: Oxygen Therapy Improves Heart Function in Long COVID Patients
A small trial has found that hyperbaric oxygen therapy (HBOT) may help restore proper heart function in patients with post-COVID syndrome, with participants in the HBOT group experiencing a significant increase in global longitudinal [...]
Wireless Brain-Spine Interface: A Leap Towards Reversing Paralysis
Summary: In a pioneering study, researchers designed a wireless brain-spine interface enabling a paralyzed man to walk naturally again. The ‘digital bridge’ comprises two electronic implants — one on the brain and another on the [...]
New study reveals a gel that promises to wipe out brain cancer for good
An anti-cancer gel promises to wipe out glioblastoma permanently, a feat that's never been accomplished by any drug or surgery. So what makes this gel so special? Scientists at Johns Hopkins University (JHU) have [...]
New production process for therapeutic nanovesicles
Particles known as extracellular vesicles play a vital role in communication between cells and in many cell functions. Released by cells into their environment, these “membrane particles” consist of a cellular membrane carrying a [...]
Could studying African killifish be the secret cure to sarcopenia?
The Australian Regenerative Medicine Institute (ARMI) at Monash University suggests that muscle wasting, known as sarcopenia, may be reversed in late-life The study utilized the African killifish as a model and found that muscles revert [...]
Virtual AI Radiologist: ChatGPT Passes Radiology Board Exam
The most recent version of ChatGPT, an AI chatbot developed for language interpretation and response generation, has successfully passed a radiology board-style exam, demonstrating both its potential and limitations, according to research studies published [...]
Harnessing Energy Waves: Smart Material Prototype Challenges Newton’s Laws of Motion
University of Missouri researchers designed a prototype of a small, lightweight active ‘metamaterial’ that can control the direction and intensity of energy waves. Professor Guoliang Huang of the University of Missouri has developed a [...]
Nanotechnology revolutionizes the way cancer-fighting T cells navigate and combat tumors
Vanderbilt researchers are bolstering the fight against cancer with technology that enhances the effectiveness of T cells that attack tumors. The cutting-edge research was recently published in the journal Science Immunology. Cancers co-opt both [...]
Molecular “Superpower” of Antibiotic-Resistant Bacteria Revealed in New Research
A species of ordinary gut bacteria that we all carry flourishes when the intestinal flora is knocked out by a course of antibiotics. Since the bacteria is naturally resistant to many antibiotics, it causes problems, particularly [...]
Human DNA Is All Over The Planet, And Scientists Are Worried
Every skin flake, hair follicle, eyelash, and spit drop cast from your body contains instructions written in a chemical code, one that is unique to you. According to a new study, technology has advanced [...]
Long COVID: The Invisible Consequence of Socioeconomic Inequality
A recent study conducted by the Universities of Southampton and Oxford reveals a strong correlation between the incidence of long COVID and the level of area-specific deprivation. It found that individuals from the most deprived regions are 46 [...]
Mutation Mystery: Unraveling the Secret Behind COVID-19’s Rapid Spread
Molecular modeling suggests structural consequences of an early protein mutation that promoted viral transmission. RIKEN researchers discovered that an early mutation (D614G) in the SARS-CoV-2 virus may have contributed to its rapid spread by altering the spike [...]
Protein nanoparticle vaccine with adjuvant improves immune response against influenza
A novel type of protein nanoparticle vaccine formulation containing influenza proteins and adjuvant to boost immune responses has provided complete protection against influenza viral challenges, according to a new study published by researchers in [...]
Decoding Long COVID: NIH Study Exposes the Inner Workings of Neurological Symptoms
A NIH study on twelve Long COVID patients found differences in immune cell profiles and autonomic dysfunction, contributing to the understanding of the condition and potentially leading to better diagnoses and new treatments. Twelve [...]
Pancreatic Cancer Vaccine Shows Promise in Small Trial
Using mRNA tailored to each patient’s tumor, the vaccine may have staved off the return of one of the deadliest forms of cancer in half of those who received it. Five years ago, a [...]