Diagnosing lupus and lupus nephritis is a challenging process. Today, rheumatologists rely on a combination of laboratory tests, symptom logs, family history, and clinical expertise. But, new research is identifying particular proteins that may be indicative of lupus.
A study published in 2018 explored the presence of an enzyme called B-cell activating factor (BAFF) that can be detected in urine. 189 people participated in the study (85 people with systemic lupus erythematosus, 28 people with primary Sjögren’s syndrome, 40 people with immunoglobulin A nephropathy, and 36 control participants). In addition to a urinalysis, the participants overall and renal lupus disease activity were measured with the SLEDAI-2000.
The researchers found B-cell activating factor “in a small but…significant proportion of SLE patients but not in the other groups tested.” It was found in 12% (10/85 people) of patients with SLE, and in 28% (5/18 people) of people with active lupus nephritis.
Previous research had explored B-cell activating factor in urine, and suggested that it could be associated with a lupus diagnosis. These studies support the theory that B-cells play a significant role in the development of lupus.
Diving deeper into B-cell activating factor
B cells are a type of white blood cell that helps the immune system identify and battle invaders in the body.
B-cell activating factor is a cytokine, a broad group of proteins that are important in cell signaling.
There are number of names for B-cell activating factor including:
- tumor necrosis factor (TNF) ligand superfamily member 13B
- B Lymphocyte Stimulator (BLyS)
- TNF- and APOL-related leukocyte expressed ligand (TALL-1)
- Dendritic cell-derived TNF-like molecule (CD257 antigen)
B-cells help combat invaders to the body by:
- “Remembering” previous diseases
- Flagging foreign invaders
- Producing antibodies (with the help of T cells)
B-cells that target the body’s own cells are usually detected and destroyed by “checkpoints” throughout the body. One of these checkpoints is in the bone marrow, where the cells are made. When cells are destroyed here, it’s called “central tolerance.” “Peripheral tolerance” is when cells are destroyed elsewhere in the body.
B-cell activating factor is an enzyme that increases the activity of B-cells. This can result in dialing up inflammation as part of the immune response. High or rising levels of B-cells and BAFF are associated with disease flares. Many forms of lupus appear to be linked to problems at these checkpoints. These problems let B-cells that target the body survive to cause autoimmune responses, and might be caused by genetic mutations, damage (from stress, injury, or disease), or as a medication side effect (a possible link to drug-induced lupus.)
Finding BAFF in the urine of people with lupus supports this idea and may open the door to more accurate tests and treatments. Tumor necrosis factor inhibitors, which block BAFF activity and reduce inflammation, are one new type of promising treatment.
What’s next for this research?
This research supports a non-invasive option for detecting lupus and telling it apart from other diseases. Measuring urinary BAFF also is at an advantage for detecting lupus nephritis, which means that it can be caught faster. It also may help distinguish drug-induced lupus from a patient’s other conditions.
Distinguishing between autoimmune diseases and symptoms can feel like splitting hairs. These syndromes can have similar symptoms to lupus and may even be co-occurring, and you can read more about that here. However, treatments often vary dramatically. You can read more about lupus treatments on LupusCorner.
Stress management, however, remains a good choice for all autoimmune diseases – find out more here.
This simple blood test doesn’t require a machine – only an hour...
Up to 1/3 of people with lupus will experience kidney involvement as...
Research is underway to measure the effectiveness of Cenerimod, a new lupus medication. Early...