Discovery holds promise for patients with Crohn's disease, diabetes, ulcerative colitis, and more.
Discovery holds promise for patients with Crohn’s disease, diabetes, ulcerative colitis, and more.
Scientists have discovered 22 genome-wide signals shared by two or more diseases, a discovery that could have major implications for the targeted treatment of autoimmune diseases. In some cases, these targeted therapies may be ready to use with existing drugs for non-autoimmune disorders.
Autoimmune diseases, such as type 1 diabetes, Crohn’s disease, and juvenile idiopathic arthritis, collectively affect 7 to 10% of the population in the Western Hemisphere.
“Our approach did more than finding genetic associations among a group of diseases,” said study leader, Hakon Hakonarson, MD, PhD, director of the Center for Applied Genomics at The Children’s Hospital of Philadelphia (CHOP). “We identified genes with a biological relevance to these diseases, acting along gene networks and pathways that may offer very useful targets for therapy.”
The international team of researchers performed a meta-analysis, including a case-control study of 6035 subjects with autoimmune disease and 10,700 controls, all of European background. The research studied 10 clinically distinct autoimmune diseases with onset during childhood including type 1 diabetes, celiac disease, juvenile idiopathic arthritis, common variable immunodeficiency disease, systemic lupus erythematosus, Crohn’s disease, ulcerative colitis, psoriasis, autoimmune thyroiditis, and ankylosing spondylitis.
Many of these diseases are hereditary and individual patients often have more than 1 autoimmune condition, which has led many clinicians to believe these conditions have shared genetic predispositions. Prior studies have identified hundreds of susceptibility genes among autoimmune diseases, largely affecting adults.
The study evaluated multiple pediatric-onset diseases simultaneously and found 27 genome-wide loci, including 5 new loci, among the diseases examined. Of those 27 signals, 22 were shared by at least 2 of the autoimmune diseases and 19 of them were shared by at least 3 of them.
Many of the gene signals identified were linked to cell activation, cell proliferation, and signaling systems important in immune processes. One of the 5 new signals, CD40LG, was especially unique in its ability to encode the ligand for the CD40 receptor. This ligand may represent another promising drug target in treating autoimmune diseases, according to Hakonarson.
“Rather than looking at overall gene expression in all cells, we focused on how these genes upregulated gene expression in specific cell types and tissues, and found patterns that were directly relevant to specific diseases,” he said. “For instance, among several of the diseases, we saw genes with stronger expression in B cells. Looking at diseases such as lupus or juvenile idiopathic arthritis, which feature dysfunctions in B cells, we can start to design therapies to dial down over-expression in those cells.”
With this new discovery, scientists can work to fine tune and expedite drug development by repurposing existing drugs and to pioneer the development of newer drugs with specific genome-targeting functionality.