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Published on: February 22, 2017
Microcystin-LR (MC-LR) Triggers Inflammatory Responses in Macrophages
Robin C Su1, Joshua D Breidenbach1, Khaled Alganem2
1Department of Medicine, The University of Toledo College of Medicine and Life Sciences, Toledo, OH 43614, USA.
Abstract:
We were the first to previously report that microcystin-LR (MC-LR) has limited effects within the colons of healthy mice but has toxic effects within colons of mice with pre-existing inflammatory bowel disease. In the current investigation, we aimed to elucidate the mechanism by which MC-LR exacerbates colitis and to identify effective therapeutic targets. Through our current investigation, we report that there is a significantly greater recruitment of macrophages into colonic tissue with pre-existing colitis in the presence of MC-LR than in the absence of MC-LR. This is seen quantitatively through IHC staining and the enumeration of F4/80-positive macrophages and through gene expression analysis for Cd68, Cd11b, and Cd163. Exposure of isolated macrophages to MC-LR was found to directly upregulate macrophage activation markers Tnf and Il1b. Through a high-throughput, unbiased kinase activity profiling strategy, MC-LR-induced phosphorylation events were compared with potential inhibitors, and doramapimod was found to effectively prevent MC-LR-induced inflammatory responses in macrophages.
Insights
Microcystin-LR (MC-LR) worsens colitis by increasing macrophage recruitment and activation in the colon. Doramapimod effectively inhibited these MC-LR-induced inflammatory responses in macrophages.
Area of Science:
- Toxicology
- Immunology
- Gastroenterology
Background:
- Microcystin-LR (MC-LR) shows differential effects in the colon, being toxic in inflammatory bowel disease (IBD) but not in healthy mice.
- Understanding the mechanism of MC-LR-induced exacerbation of colitis is crucial for developing targeted therapies.
Purpose of the Study:
- To elucidate the mechanism by which MC-LR exacerbates colitis.
- To identify potential therapeutic targets for MC-LR-induced inflammation in IBD.
Main Methods:
- Quantitative assessment of macrophage recruitment using immunohistochemistry (IHC) for F4/80.
- Gene expression analysis of macrophage markers (Cd68, Cd11b, Cd163) and activation markers (Tnf, Il1b).
- High-throughput kinase activity profiling to identify MC-LR-induced phosphorylation events and potential inhibitors.
Main Results:
- MC-LR significantly increased macrophage recruitment into colonic tissue of mice with pre-existing colitis.
- MC-LR exposure directly upregulated inflammatory markers Tnf and Il1b in isolated macrophages.
- Doramapimod effectively inhibited MC-LR-induced inflammatory responses in macrophages.
Conclusions:
- MC-LR exacerbates colitis through enhanced macrophage recruitment and activation.
- Targeting specific kinase pathways, such as with doramapimod, may offer a therapeutic strategy against MC-LR-induced inflammation in IBD.
