Luminal Extracellular Vesicles (EVs) in Inflammatory Bowel Disease (IBD) Exhibit Proinflammatory Effects on Epithelial Cells and Macrophages

Abstract

Background Extracellular vesicles (EVs) are membrane-enclosed particles released by cells as a means of intercellular communication. They are potential novel biomarkers, as they are readily isolated from body fluids, and their composition reflects disease pathways. Whether these particles are released from sites of intestinal inflammation in Inflammatory Bowel Disease (IBD) has not previously been determined. Methods EVs were isolated by ultracentrifugation of colonic luminal fluid aspirates, and characterized according to surface proteins, and constituent mRNA and proteins. The effects of EVs on colonic epithelial cells and macrophages in culture were assessed at the transcriptional, translational and functional levels. Results Intestinal luminal aspirates contained abundant EVs, at a mean concentration of 4.3 × 1011 particles/mL, and with a mean diameter of 146nm. EVs from IBD patients with a high endoscopic score (≥1) contained significantly higher mRNA and protein levels of IL-6, IL-8, IL-10 and TNF-α than EVs from healthy controls. EVs were absorbed by cultured colonic epithelial cells, leading to an increased translation of IL-8 protein by recipient cells when treated with EVs from IBD patients. EVs and EV-treated epithelial cells induced migration of a significantly greater number of macrophages than epithelial cells alone. Conclusions EVs shed from sites of intestinal inflammation in IBD patients have a distinct mRNA and protein profile from those of healthy individuals. These EVs have pro-inflammatory effects on the colonic epithelium, in vitro. Their stability in luminal samples, and their mRNA and protein content, identify them as a potential fecal biomarker that reflects mucosal inflammatory pathways.

Exosomes in Inflammation and Inflammatory Disease

“…Epithelial cells and macrophages could be activated by luminal exosome treatment, leading to increased production of IL-8 and migratory activity when compared with controls. [62] In animal studies, exosomes isolated from DSSinduced acute colitis mice or Crohn's disease related adherentinvasive Escherichia coli (AIEC)-infected intestinal epithelial cells and macrophages could activate naïve macrophages through activation of NF-κB, ERK, p38, and JNK, and result in increased secretion of pro-inflammatory cytokines TNF-α and IL-6. [14,63] In addition to activating immune and inflammatory responses, depending on the state or type of their parental cell, exosomes have also been shown to suppress the same responses.…”

Extracellular vesicles regulate immune responses and cellular function in intestinal inflammation and repair

“…EVs can be readily isolated from bodily fluids, such as serum, 50 saliva, 51 urine, 52 and in the intestine from luminal aspirates. 53 The number of EVs and their composition can reflect both healthy and pathological states. 54 Specifically, in IBD an increased number of EVs in the serum and the intestinal lumen 53 was correlated with disease severity and were shown to contain immune cell-and IEC-specific markers as well as many inflammatory markers associated with the diseases.…”

Purinergic signaling during intestinal inflammation

“…In addition, these MP constitute a mode of communication through which intestinal cells may influence the luminal microbiome. We have recently reported that extracellular vesicles, derived from the colonic luminal fluid of IBD patients, display pro-inflammatory properties as these MP contain high mRNA and protein levels of IL-6, IL-8, IL-10 and TNF-α, and promote macrophage migration (41). We have also shown that CD39 associates with circulating plasma-derived MP and may directly or indirectly confer functional properties on cells.…”