Mar. 04, 2011

Are MicroRNAs Novel Biomarkers for Lupus Nephritis?

Identification of unique microRNA signature associated with lupus nephritis
Te JL, Dozmorov IM, Guthridge JM, Nguyen KL, Cavett JW, Kelly JA, Bruner GR, Harley JB, and Ojwang JO. (2010). PLoS One 5: e10344.

What is the topic?
People inherit DNA from their parents and it contains the blueprints for making all of the proteins in the body. RNA is the translating material which helps in the conversion of these blueprints into functioning proteins. MicroRNAs are small pieces of RNA that help to regulate the extent to which instructions for making specific proteins can be used for that purpose. Specific blueprints can be “turned off” by microRNAs so that some proteins won’t be made.  

The role of microRNAs in lupus has recently been studied. Specific microRNAs have been identified in lupus patients and in some patients who have kidney involvement (lupus nephritis). 

What did the researchers hope to learn?
The researchers hoped to learn whether people with lupus kidney involvement from different races shared the same set of microRNAs.  

Who was studied?
26 lupus patients and 26 healthy people donated blood samples that were used in this study. At least 24 samples came from people with lupus nephritis, most of whom were being treated with steroids such as prednisone.

How was the study conducted?
RNA was isolated from the blood cell samples and different kinds of microRNAs were indentified. Initially, 10 samples from African Americans with lupus kidney involvement were compared to those from healthy African Americans. 5 other samples from African Americans with lupus were compared to those of 5 healthy African Americans and 10 samples from European Americans with lupus were compared to those of 10 healthy European Americans.

What did the researchers find?
A number of microRNAs were different in African American patients with lupus or lupus nephritis compared to healthy African Americans. Most were increased in lupus patients but some were decreased.  

The same kind of thing was found when European Americans with and without lupus were compared. Most of the microRNAs that were different were increased in lupus patients, but some were decreased.    

Differences in levels of 5 specific microRNAs were shared by the lupus patients regardless of race. Of these, two were the same as microRNAs previously found to be associated with lupus nephritis in Chinese patients, and three have never been previously reported. These 5 microRNAs are known to regulate blueprints for interferons, proteins that are important in lupus and the activity of the immune system. 

What were the limitations of the study?
This study analyzed samples from a limited number of patients. It is unlikely that all important microRNA differences have been found and it is not known how important these particular ones are.  

What do the results mean for you? 
The microRNAs reported in this study could one day help to predict risk for nephritis, or even be used to track the progress of certain treatments for nephritis. It is even possible that they could help find ways to diagnose nephritis that might someday eliminate the need for a kidney biopsy. However, it may take a long time, and further studies will definitely be required before this kind of testing could be understood well enough to be useful, and then to become more widely available or routine.   


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