Genomics and Immunity · eu
3D Gene Atlas of Rare Immune Cells Reveals More Than 100 Crohn’s Disease Candidate Genes
A chromosome-capture technique designed for small samples linked disease-risk variants back to genes they may regulate and unexpectedly pointed to CLN3; however, the findings remain a preprint, and the functional evidence comes primarily from mouse cells.
Genetic studies of Crohn’s disease have identified many risk variants, but most lie in regulatory regions that do not produce proteins. Determining which genes they affect often cannot be done based solely on linear distance along the chromosome. A preprint study instead examined the three-dimensional folding of DNA within the nucleus, tracing the genes that these variants may contact and control in rare group 3 innate lymphoid cells (ILC3s).
ILC3s reside in mucosal tissues such as the gut and respiratory tract, where they help maintain barriers and also participate in inflammatory responses. Using promoter capture Hi-C adapted for small numbers of cells, the research team analyzed three sets of primary human ILC3 samples, mapping tens of thousands of contacts between promoters and distal regulatory regions. They also compared the results with CD4-positive T cells to identify chromosomal connections more specific to ILC3s.
The researchers then integrated this three-dimensional contact map with data from Crohn’s disease genome-wide association studies. Using a Bayesian analytical framework called multiCOGS, they linked risk variants to potential target genes. The analysis proposed more than 100 candidate genes, including familiar immune-related signals such as IL23R as well as CLN3, which had not previously been regarded as a key player in intestinal inflammation.
CLN3 is best known because pathogenic variants in the gene can cause neurodegenerative diseases such as Batten disease. In ILC3-like mouse cells, the team found that Cln3 expression decreased following stimulation with inflammatory cytokines. Experimentally increasing its expression altered the stimulation-induced transcriptional program and cytokine secretion. These results support the possibility that CLN3 helps regulate the inflammatory state of ILC3s, but they are not sufficient to prove that it directly causes Crohn’s disease.
The same method was extended to five other autoimmune diseases. The resulting candidate genes were enriched among findings from a CRISPR interference screen of inflammatory responses in ILC3s, indicating that three-dimensional genome data may help supply the cell-type context missing from conventional genetic association analyses. At present, its value lies more in narrowing the scope of follow-up experiments than in immediately providing diagnostic markers or therapeutic targets.
This work still has important limitations. PubMed explicitly labels it as a bioRxiv preprint that has not undergone peer review, rather than a paper formally published in *Nature Genetics*. The main gene map was derived from a small number of healthy human cell samples, while the functional testing of CLN3 used a mouse cell line and artificial overexpression. The relevant regulatory effects may vary with cellular state and the inflammatory environment, and will still need to be validated in human intestinal tissue, patient-derived ILC3s, and models that more closely reflect physiological conditions.