Researchers at Stanford University (USA) have discovered that one of humanity’s most ubiquitous infectious agents is responsible for the chronic autoimmune disease known as systemic lupus erythematosus, colloquially known as lupus.
This is the Epstein-Barr virus (EBV). … Also known as the kissing virus, it is present in almost everyone.. This virus causes abnormalities in some immune cells and activates many others, causing a massive attack by the immune system against the body’s own tissues.
The results will be published in Science Translational Medicine.
“We believe this is true in 100% of cases of lupus,” says William Robinson, lead author of the study.
An estimated 5 million people worldwide suffer from lupus, a disease in which the immune system attacks the contents of cell nuclei. This causes damage to organs and tissues throughout the body, including the skin, joints, kidneys, heart, and nerves, and symptoms vary greatly from person to person.
The reason is unknown, but 9 out of 10 people with lupus are women.
Fortunately, with proper diagnosis and medication, most lupus patients can lead normal lives, but for about 5% of them, the disease can be fatal. Current treatments slow the progression of the disease but do not cure it.
By the time we reach adulthood, the majority of us have been infected with Epstein-Barr virus (EBV). EBV infection, which is transmitted through saliva, usually occurs during childhood when sharing a spoon or drinking from the same glass with a sibling or friend, or perhaps during adolescence when a kiss is exchanged.
What EBV can cause Mononucleosis, also known as the “kissing disease”The fever subsides, but is replaced by deep fatigue that can last for months.
“Pretty much the only way to avoid getting EBV is to live isolated from the rest of the world,” Robinson explains. “If you live a normal life, the chance of developing the disease is approximately 20 to 1.”
What’s more, once you’ve been infected with EBV, you can’t eliminate it, even if you remain asymptomatic or become asymptomatic, Robinson explains.
The vast majority of people infected with EBV (or more accurately, most of us) are unaware that they continue to carry the virus and never develop lupus.
EBV belongs to a large family of viruses that includes the viruses that cause chickenpox and herpes, and can deposit genetic material into the nucleus of infected cells. There, the virus remains hidden from the immune system’s surveillance agents and remains dormant. This can last as long as the hidden cells are alive. Alternatively, under certain conditions, the virus can reactivate and force the infected cell’s replication machinery to produce countless copies of itself, which can then spread and infect other cells and people.
EBV persists in B lymphocytes, immune cells that serve two important functions. One is to produce antibodies that recognize and bind to pathogen antigens, and the other is to act as antigen-presenting cells, displaying these fragments on their surface to activate other cells of the immune system and enhance the protective response.
autoimmune disease
Our bodies contain hundreds of billions of B lymphocytes that can produce a wide variety of antibodies, allowing us to respond to a wide variety of pathogens. However, approximately 20% of these cells are autoreactive and can recognize their own antigens through a random process that creates diversity. Normally they remain inactive, but when activated they can attack the body’s tissues and cause autoimmune diseases such as lupus, where anti-nuclear antibodies damage multiple organs.
The vast majority of people infected with the Epstein-Barr virus (or more accurately, most of us) do not realize that they continue to carry the virus and never develop lupus. However, various studies have shown that virtually all lupus patients are infected. A link between this virus and lupus has long been suspected but had not been confirmed until now.
Almost everyone carries EBV in latent form, but only a small proportion of B lymphocytes are infected. Thanks to new sequencing technology, researchers discovered that while in healthy people less than 1 in 10,000 B lymphocytes contain the virus, that rate increases to 1 in 400 in lupus patients.
EBV activates the production of a viral protein called EBNA2, which acts as a transcription factor and activates human genes associated with inflammation. This makes the B cells more inflammatory and able to stimulate helper T cells that attack the nuclear components. These, in turn, may recruit more autoreactive B and T lymphocytes, triggering a systemic autoimmune response and ultimately causing lupus relapse.
Dr. Robinson believes that the cascade of autoimmune B cell activation triggered by EBV may extend beyond lupus to other autoimmune diseases such as multiple sclerosis, rheumatoid arthritis, and Crohn’s disease, where evidence of EBV-initiated EBNA2 activity has been observed.
vaccine
The million dollar question: If approximately 95% of us harbor Epstein-Barr virus (EBV) latently in our B lymphocytes, why do some, but not all, develop autoimmunity?
Robinson speculates that perhaps only certain strains of EBV induce the transformation of infected B cells into antigen-presenting cells, leading to widespread activation of large numbers of antinuclear B cells.
Many companies are working on developing an EBV vaccine, and clinical trials are already underway. However, Robinson believes the vaccine should be given soon after birth because it cannot eliminate the virus from someone who has already been infected.
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