Several researchers at the Departments of Pathology and Genome Sciences of the University of Washington have identified a putative autoantigen in an uncommon kidney disease.
Fibrillary glomerulonephritis (GN) is a condition that affects the glomeruli in the kidney. The disease leads to progressive renal dysfunction, and individuals with the disease often need dialysis a few years after diagnosis. The etiology of fibrillary GN remains obscure. The glomerulus, plural glomeruli, is the basic filtration unit of the kidney. There are millions of glomeruli in the kidney. In fibrillary GN, a large volume of unusual proteins are produced by the body and get trapped in the straining layers of the glomeruli, reducing the kidneys' ability to filter and clean the blood. Sometimes, the trapped proteins activate the immune system.
In this work, the researchers employed the technique mass spectrometry (MS) to investigate the glomerular proteome in fibrillary GN, in non-fibrillary GN kidney disease, as well as in healthy controls. A protein, called DNAJB9
, was only detected in fibrillary GN. The discovery is a progress in this field that it would have implications for the diagnosis and treatment of fibrillary GN. In addition, IgG1 was the major immunoglobulin (Ig) of the glomerular proteome in fibrillary GN. Furthermore, immunofluorescence and immunohistochemistry analyses of patient samples confirmed that DNAJB9 was abundant in fibrillary GN. Taken together, the results suggest DNAJB9 as a putative autoantigen in fibrillary GN.
The study, titled "DnaJ Homolog Subfamily B Member 9 Is a Putative Autoantigen in Fibrillary GN," was published online before print in the Journal of the American Society of Nephrology on November 2, 2017.
Currently, the diagnosis of fibrillary GN requires using electron microscopy and other techniques to reveal the presence of protein deposits in the kidney tissues. This method is complex and takes a relatively long period of time. Besides, there is no effective and specific therapy for fibrillary GN. Identification of DNAJB9 as an autoantigen in fibrillary GN would help develop diagnostic and therapeutic methods for the disease. DNAJB9, short for DnaJ homolog subfamily B member 9, is a member of the molecular chaperone gene family.