Urine Components May Indicate Severity of Lupus Nephritis
- Urine cyto/chemokines correlate with renal histopathology in systemic lupus erythematosus. (2009).
American College of Rheumatology Abstracts 564.
What is the topic?
Lupus may involve inflammation of the kidney, called lupus nephritis, which can impair the kidney’s ability to remove waste from the body. Since normal kidney function is vital, lupus nephritis requires aggressive treatments. Currently, the best way to diagnose kidney inflammation is with a biopsy, which is an invasive procedure that can sometimes have serious side effects. If there were tests that could be done to help diagnose and evaluate lupus nephritis without a biopsy, this would be a major advance for patients.
Inflammatory chemicals called cytokines and chemokines act like little bullets to help to control the degree of inflammation that is caused by the immune system. In lupus nephritis, they play a critical role in kidney inflammation. Since these tiny bullets of the immune system can be collected from urine, a measurement of how much they are appearing in urine may be used to reveal valuable information about kidney disease in lupus patients.
What did the researchers hope to learn?
The researchers wanted to find out whether the amount of some specific cytokines and chemokines were correlated with the severity of lupus kidney disease activity, as revealed by kidney biopsy.
Who was studied?
Twenty-two patients who had lupus and were scheduled for a kidney biopsy volunteered for this study, as well as 19 healthy people, to compare the inflammatory cytokines and chemokines in people who have no illness.
How was the study conducted?
Urine was collected at the same time as the kidney biopsy in the lupus patients. Based on kidney biopsy results, lupus patients were divided into a group with active kidney inflammation or a group with inactive disease. For each lupus patient, the urine concentrations of four cytokines or chemokines were measured and a number score was given, based on the overall sum of these findings. The specific names of the cytokines or chemokines that were measured were IP-10, MCP-1, adiponectin, and IL-15. Since there is no previously accepted definition for what is an "elevated level," the definition of elevated was based on the results of the healthy people, as long as it was equal to or greater than a mathematical calculation called two standard deviations above the average levels of the healthy people. A global score was calculated that factored in all four of these inflammatory chemicals, taken together.
What did the researchers find?
The researchers found that urine concentrations of all four of these, measured individually, were higher in lupus patients than healthy people. In addition, they found that lupus patients who had active kidney disease showed significantly increased global scores as compared with lupus patients having inactive kidney disease.
What were the limitations of the study?
These results show a relationship between the levels of urinary cytokines or chemokines and the severity of kidney disease seen in a kidney biopsy. However, the type of relationship is not yet known. Does the kidney disease cause the high levels of inflammatory chemicals measured? Or is it the other way around? Or does a third factor cause both?
What do the results mean for you?
The results of this study suggest the possibility that, in the future, the type and severity of kidney disease in lupus patients could be diagnosed based only on a urine test, avoiding a biopsy. It is also possible that as people are treated for nephritis, following these easy-to-get markers might help to know how effective the treatment is, allowing optimal adjustments in medications early in the course of treatment and better outcomes. For some patients, if these markers would show improvement earlier than usual, it might be possible to reduce the dose or shorten the course of some of these potentially toxic treatments.