Depletion of enteric bacteria diminishes leukocyte infiltration following doxorubicin-induced small intestinal damage in mice

Abstract

Background & aimsWhile enteric bacteria have been shown to play a critical role in other forms of intestinal damage, their role in mediating the response to the chemotherapeutic drug Doxorubicin (Doxo) is unclear. In this study, we used a mouse model of intestinal bacterial depletion to evaluate the role enteric bacteria play in mediating Doxo-induced small intestinal damage and, more specifically, in mediating chemokine expression and leukocyte infiltration following Doxo treatment. An understanding of this pathway may allow for development of intervention strategies to reduce chemotherapy-induced small intestinal damage.MethodsMice were treated with (Abx) or without (NoAbx) oral antibiotics in drinking water for four weeks and then with Doxo. Jejunal tissues were collected at various time points following Doxo treatment and stained and analyzed for apoptosis, crypt damage and restitution, and macrophage and neutrophil number. In addition, RNA expression of inflammatory markers (TNFα, IL1-β, IL-10) and cytokines (CCL2, CC7, KC) was assessed by qRT-PCR.ResultsIn NoAbx mice Doxo-induced damage was associated with rapid induction of apoptosis in jejunal crypt epithelium and an increase weight loss and crypt loss. In addition, we observed an increase in immune-modulating chemokines CCL2, CCL7 and KC and infiltration of macrophages and neutrophils. In contrast, while still positive for induction of apoptosis following Doxo treatment, Abx mice showed neither the overall weight loss nor crypt loss seen in NoAbx mice nor the increased chemokine expression and leukocyte infiltration.ConclusionEnteric bacteria play a critical role in Doxo-induced small intestinal damage and are associated with an increase in immune-modulating chemokines and cells. Manipulation of enteric bacteria or the damage pathway may allow for prevention or treatment of chemotherapy-induced small intestinal damage.

Polychemotherapy with Curcumin and Doxorubicin via Biological Nanoplatforms: Enhancing Antitumor Activity

“…Studies have shown the importance of gut microbiota in DOX toxicity. It seems that gut microbiota depletion leads to a decrease in DOX-mediated toxicity in heart, kidney, liver and intestine [ 154 , 155 ]. Following DOX exposure, gut dysbiosis occurs that may lead to disruption in the intestinal barrier.…”

Doxorubicin increases permeability of murine small intestinal epithelium and cultured T84 monolayers

“…This leads to mucosal damage characterized by impaired epithelial proliferation, loss of crypts, and villus blunting 1 . Concomitantly, we observed significant increases in chemokine expression and infiltration of macrophages and neutrophils into the lamina propria space surrounding crypts 2 .…”

“…We subsequently demonstrated that this mucosal damage and innate immune response is dependent on the presence of enteric bacteria by comparing conventionally raised mice to germ free mice and mice treated with oral antibiotics 2 , 3 . While the initial apoptosis still occurred in the epithelium of germ free and antibiotic-treated mice after DXR, the subsequent chemokine production, immune cell infiltration, and mucosal damage were prevented 2 , 3 . Others have demonstrated that prevention of signaling (e.g.…”

Doxorubicin Induces Senescence in Intestinal Epithelial Cells

“…(31) The absence of enteric bacteria in germ free mice or pretreatment of mice with high-dose oral antibiotics to deplete enteric bacteria prevented this infiltration of immune cells and ameliorated crypt loss. (31,32) This correlation between the bacteria, innate immune cells and crypt loss could involve the interaction of epithelial cell-derived alarmins with infiltrating immune cells and should be further studied.…”

“…(28-30) We have previously demonstrated that treatment of mice with DXR induces an acute inflammatory response that included infiltration of macrophages and neutrophils into the peri-cryptal space concomitant with crypt loss and mucosal damage. (31) The absence of enteric bacteria in germ free mice or pretreatment of mice with high-dose oral antibiotics to deplete enteric bacteria prevented this infiltration of immune cells and ameliorated crypt loss (31,32). This correlation between the bacteria, innate immune cells and crypt loss could involve the interaction of epithelial cell-derived alarmins with infiltrating immune cells and should be further studied.Finally, our results suggest that proliferative intestinal epithelial cells can have disparate responses to exposure to DXR by either becoming apoptotic or senescent.…”