What Causes Lupus?

Both men and women produce estrogen, though women make much more and are about nine times more likely to get lupus than men. Many women with lupus have increased systems before their periods, indicating that estrogen may be a contributing factor. Research suggests this may be due to estrogen's role in how cells function and regulation of the immune system, specifically mitochondrial function and cytokine regulation.

Race seems to play a significant role in lupus. Black women are two to three times more likely to get lupus than white women, and black and Hispanic women are more likely to have severe forms. Researchers have not determined why, but one study in the U.S. found significant differences in how lupus affects whites, blacks, Hispanics, and Asian-Pacific Islanders (APIs).

For example, blacks, APIs, and Hispanics are more likely to have symptoms related to the kidneys, nervous system, and blood than whites, and they appear much sooner, within the first year of the onset.

Environmental factors may also contribute to the development of lupus. Research shows that living in an urban environment influences the risk of developing lupus and the severity of the symptoms. Multiple environmental factors may contribute, including ultraviolet radiation, air pollution, and heavy metals.

Viruses, bacteria, and other infectious agents can cause an abnormal immune response in people susceptible to lupus. One of the most prevalent infectious causes of lupus symptoms is the Epstein-Barr virus (EBV).

Many studies have determined that EBV is related to autoimmunity, and people with lupus have more antibodies against EBV and are more likely to have an EBV infection than the general population.

Although lupus is not exclusively hereditary, scientists have found a specific genetic component. Researchers identified a genetic mutation in the TLR7 gene, a toll-like receptor gene involved in the body's immune response. The mutation appears to increase the sensitivity of the gene, making it more likely to attack healthy tissue.

One study conducted by Harvard T.H. Chan School of Public Health and Brigham and Women’s Hospital found that women with post-traumatic stress syndrome (PTSD) were three times more likely to have lupus. Women exposed to trauma who were not diagnosed with PTSD had double the risk, indicating that stress and trauma may be linked to lupus.

The sample for this study was primarily white women, however, so more research is needed to see how these factors affect women of color regarding lupus.

Research shows that not only does cigarette smoking act as an environmental trigger for lupus, but it can also affect treatment. Cigarette smoking interacts with genes and causes inflammation, which can cause or exacerbate symptoms of lupus in people prone to it.

Studies also show that smoking can blunt the effects of some medications, which can lead to an increase in symptoms and poor disease control.

A few medications are known to cause lupus, primarily procainamide, which treats heart arrhythmias, and hydralazine, used to treat high blood pressure. People taking procainamide have about a 30 percent chance of developing lupus; for hydralazine, it's between five and ten percent.

Drug-induced lupus can take weeks or months to develop, so it can be hard to diagnose. Joint pain is often the first symptom and occurs in 90 percent of cases.

The relationship between lupus and diet is complex, but research shows that multiple dietary factors may affect the onset and severity of lupus symptoms.

For example, certain lipids, namely EPA and DHA, may benefit people with lupus, and multiple vitamins, including vitamins A, B6, and D, can help reduce oxidative stress and inflammation. Restricting zinc has also been shown to be beneficial for lupus symptoms.

Gut bacteria have been linked to many immune-related diseases, and research shows they may be a contributing factor to lupus. One study found that study participants diagnosed with lupus had five times more of a bacteria called R. gnavus in their gut. These women also experienced flares that included skin rash, joint pain, and severe kidney dysfunction when they had increases in this bacterial growth.

More research is needed, but the connection between gut health and lupus may lead to new treatment methods, including probiotics and fecal transplants.

There are three types of radiation from the sun: UVA, UVB, and UVC. UVA has the longest wavelengths; UVC is the shortest. UVA rays can penetrate through the top layer of your skin; UVB, because they are shorter, cannot. Some UVA rays, called UVA2, and UVB can exacerbate lupus symptoms, while UVA1 may have protective effects.

People with lupus also need to be careful with some indoor lighting; halogen lamps, incandescent bulbs, and fluorescent bulbs all emit varying levels of UV radiation. Even low-level exposure can cause skin damage over time.

Although it is unclear why, there seems to be a link between asthma and lupus. A meta-review of multiple studies found that people with asthma have an elevated risk of developing lupus. Another study done over 11 years found that people with lupus have a significantly higher incidence of asthma than the general population and speculates that the cause may be related to dysregulation of the immune system.

Research shows that many other disorders are associated with lupus. These include autoimmune hepatitis, biliary cirrhosis, Grave's disease, and even a history of gum disease. Anemia affects more than half of people with lupus and usually appears before symptoms begin.

Lupus affects women significantly more than men. In fact, nearly 80 percent of people with autoimmune diseases are women. Part of this may be due to estrogen, but researchers believe it may also be linked to X chromosomes. Women born with two X chromosomes may have more active genes linked to the X chromosome, like TLR7.

Women with lupus who have these genes active on both of their X chromosomes have more severe symptoms than women who do not. Men with Klinefelter’s syndrome have two X chromosomes and a Y chromosome and are 14 times more likely than other men to develop lupus, and women with trisomy X, who have three X chromosomes, are two and a half times more likely to develop lupus than women with two X chromosomes.