bloodPatients with inflammatory bowel disease (IBD) experience abdominal pain, diarrhea, rectal bleeding, and weight loss. As these symptoms develop, the cellular environment of the intestine changes dramatically. However, scientists know little about the cellular landscape of this remodeling as the disease progresses.
A research team led by a single-cell biologist has set out to spatially map these cellular pathways in the gut. Jeffrey Moffitt Boston Children’s Hospital and Immunologist Ronnie Nowarski Researchers at Brigham and Women’s Hospital imaged RNA molecules in intestinal cells before, during, and after inflammation in a mouse model of colitis. CellThe team showed that as the disease progressed, there was a progressive spatial transformation of the intestine, which was shaped in part by the presence and distribution of different subpopulations of inflammatory-associated fibroblasts.One Even after weeks of removing the drug causing the colitis, some of these fibroblasts retained their memory of the inflammation.
“In biology, spatial context is important,” he said. Kylie JamesMucosal immunologist at the Garvan Institute of Medical Research, who was not involved in the study. Knowing where the cells are located in the gastrointestinal wall is important for understanding their role in inflammatory processes and their contribution to disease. “Traditionally, this information has been lost,” she explained, because researchers often analyze these cells after they have been removed from the tissue. Prior research We used spatial transcriptomics to map cellular signatures within the gut architecture. “One of the unique aspects here is that we look at the entire inflammatory pathway and do this. [at] “Multiple time points are needed to understand how cell properties change,” James said.2,3
In this study, the researchers used a spatial transcriptomics technique called multiplex error-robust fluorescence in situ hybridization (MERFISH) to track gene expression trajectories throughout the disease progression. They mapped 940 genes in the colon of mice before administration of anti-colitis drugs (day 0), during the early disease period (day 3), at the peak of inflammation (day 9), and after recovery (days 21 and 35).
Using this data, they identified 25 tissue neighborhoods, statistically defined as recurrent local cell sets. Each neighborhood was composed of a unique mixture of different cell types, such as epithelial, endothelial, immune, and fibroblasts, in specific proportions. Some neighborhoods were present in all stages (e.g., healthy and diseased), while others were unique to a specific time point.
The researchers found that as the disease progressed, the prevalence of many neighborhoods changed. Healthy neighborhoods decreased in number, and inflamed neighborhoods appeared. One characteristic of most of these disease-induced neighborhoods was the presence of different subpopulations of inflammatory fibroblasts that originated from healthy fibroblasts. Fibroblasts are key immune regulators, majority research Previously, it has been suggested that there is a degree of heterogeneity in inflammatory fibroblasts during IBD.4,5 In this study, we identified inflammation-associated fibroblast subpopulations that differed in gene expression, spatial location, and disease stage.
“At a functional level, we still don’t really understand what the different subpopulations of fibroblasts do,” Nowarski said. “What we’ve been able to show in this study is that there’s some underappreciated diversity in the fibroblast subpopulations.”
Some of these fibroblast populations persisted with inflammatory markers for weeks after the colitis had resolved, pointing to a potential memory for the disease. “That’s really interesting, because in a human setting, people [IBD] “Even when they are in remission, their gut is still different from a healthy person,” James said. For example, many patients have intermittent and unpredictable Relapse.6 “I think of the kind of temporal information. [presented in this study] “It may help us understand IBD even when there is no active inflammation.”
Moffitt, Nowarski, and their colleagues mined published human data from other groups and found human homologues of many molecular markers of inflammatory status in fibroblast subpopulations from patients with ulcerative colitis. This suggests that the inflamed human colon may harbor different inflammatory-associated fibroblast subpopulations that undergo changes similar to those reported in this study.
But the authors stressed that fibroblasts aren’t the only cells that undergo transformation. “We see almost every type of cell responding to disease,” the co-authors said. Paolo Cardinu A study from Boston Children’s Hospital and Harvard Medical School. This may seem like a trivial conclusion, but “at the same time [it] It’s also very powerful because it tells us that future research needs to look at the really detailed parts, not just focus on the how. [a few cell types] “I am participating in the disease.”
