More than 200,000 people in the United States are estimated to have systemic lupus erythematosus (SLE), the most common form of lupus and generally referred to as lupus, according to the Centers for Disease Control and Prevention.

• Lupus is a complex autoimmune disease in which the immune system turns on the body, producing antibodies that attack the skin, joints, kidneys, brain or other organs.
• In the study, the researchers compared the blood samples of people with lupus to a control group to measure the amount of certain white blood cells, T cells. Participants with lupus had higher levels of a specific T cell associated with the production of antibodies that can attack the body.
• The researchers worked backward, following the chain of events in the immune system and identified insufficient activity of a receptor in the T cells, a protein called aryl hydrocarbon, as a potential root cause of the disease.
• Now, they’re studying whether a novel therapy could activate that receptor, leading the T cells to behave differently and, ultimately, through a cascade of events in the immune system, treat the autoimmune disease.
• The research was conducted in the lab and relied on blood samples from a small set of patients with lupus. Future studies will need to determine whether the findings are broadly applicable to others with the autoimmune disease.

“This doesn’t give us a cure for lupus tomorrow but this helps us understand specific ways that we can disrupt the abnormal immune response,” Rao said. “We’re optimistic about this leading to a new set of therapies to inhibit autoimmune conditions like this.”

The study received grant funding from Merck Sharp & Dohme, a health-care company, and Janssen Research & Development. Some of the co-authors of the study were employees of AstraZeneca, a biopharmaceutical company, and Janssen while the study was conducted.

Rao said he’s filed a patent application for a drug based on the results of the study with co-authors, Jaehyuk Choi, an associate professor of dermatology and biochemistry at Northwestern University Feinberg School of Medicine and a senior author of the Nature study, and Calvin Law, a graduate student at Northwestern University.

The hope for a cure is premature, but the study findings are “a promising pathway to look at and think about in terms of providing a more sophisticated way of treating lupus,” said Anca Askanase, a professor of medicine, the director of the Lupus Center and the director of rheumatology clinical trials at Columbia University.

The four main types of lupus are SLE; neonatal and pediatric lupus erythematosus; discoid lupus erythematosus; and drug-induced lupus.

Women, people of color and those with a family history of autoimmune disease are at a greater risk from autoimmune disorders, for reasons not clearly understood.

The cause of lupus is unknown, experts said, but “genetic, hormonal, immunological, and environmental factors all play a role in the development of SLE,” according to a review.

“While lupus is not an immediately deadly disease like cancer, it robs people of a lot in their everyday lives and in years of life as well,” Askanase said.

Lupus can affect a number of organs, and symptoms can vary, experts said. People with SLE generally experience fever, fatigue and weight loss.

Pulmonary symptoms of lupus include shortness of breath, coughing and painful breathing, while gastrointestinal signs include nausea, vomiting and abdominal pain. Cardiovascular symptoms include coronary artery disease, pericarditis and myocarditis. Some patients suffer from anemia, leukopenia or thrombocytopenia. Kidney function can be affected in lupus, and about 50 percent of patients develop nephritis.

When lupus affects the joints, patients report pain, stiffness and inflammation. They are often diagnosed with arthritis, arthralgias or myalgias. And those with skin symptoms most commonly have a “butterfly” or red rash on the nose and cheeks after sun exposure. Other patients may suffer from alopecia, and mouth or nose sores.

Depression, anxiety and cognitive impairment are among the symptoms when lupus affects the central nervous system.

There is no cure for lupus, but treatments are “evolving quickly,” Karen Costenbader, a professor of medicine at Harvard Medical School and director of the Lupus Program at Brigham and Women’s Hospital, who was a researcher on the Nature study, said in an email.

“In the past, medical providers treated the symptoms with steroids, which could have severe side effects, but there are several new and more targeted immunosuppressant medications that have become available and more are in development,” said Costenbader, who is also chair of the Lupus Foundation of America’s Medical-Scientific Advisory Council.

There are several medications to treat it, including hydroxychloroquine and other antimalarials. Many patients take a combination of drugs. These drugs can have side effects, some of which can be serious.

“Many therapies for lupus still are what we’d call broadly immunosuppressive,” Choi said. “If we could find molecular root causes of lupus, we could design potentially safer, more effective therapies.”

Diagnosis and treatment of lupus are challenging, experts said.

“You could have 300 patients in the same room, and they will have different clinical manifestations of lupus,” said Jill P. Buyon, director of the Division of Rheumatology and the Lupus Center at NYU Langone Health, who was not involved in the study.

It is hard to think of a “one size fits all” treatment, she said. The findings of this study are perhaps “taking us to precision medicine, where we could evaluate — exactly as Deepak Rao has done beautifully — let’s take our patients, let’s categorize them and those that fit into this paradigm, that’s the therapy we know to give them.”

“It’s a great paper. Incredibly well done,” Buyon said. “Is it the root cause? I don’t know if it’s the root cause. It might be a root cause.”

“There are newer biologic medications, such as belimumab, which targets the B lymphocyte stimulator, and anifrolumab, which blocks a protein called interferon that also signals to lymphocytes and stimulates them,” Costenbader said.

Several more potentially effective medications are in lupus clinical trials, she said. “Studies using chimeric antigen receptor (CAR) T lymphocytes raise hope that very effective inhibition of B cell responses may provide one path to a cure. The Nature study suggests a different but related strategy — altering the ability of T cells to stimulate abnormal B cell responses,” she said.

There has been “enormous progress” and the possibility of a cure because of investigators and “the extraordinary gift from people, volunteers that participate in observational research and clinical trials,” Askanase said.

Several other autoimmune diseases such as Sjogren’s disease and rheumatoid arthritis have an excess of the T cells found in lupus patients, and the therapeutic treatment researchers proposed “could be beneficial across many of these diseases,” Rao said in an email.