Inflammatory bowel diseases (IBD) increase the risk of developing colorectal cancer. Dietary components that reduce inflammation are associated with lower cancer risk. The long-chain omega-3 fatty ...acid docosahexaenoic acid (DHA) is present in fish oil and has potent anti-inflammatory properties. The objective of this study is to determine whether dietary fish oil enriched with DHA (DFO) could reduce experimentally induced colitis and colon cancer risk in a mouse model. When SMAD3-/- mice are exposed to Helicobacter hepaticus, mild colitis is observed 4 weeks postinfection. Mice were fed isocaloric diets modified to include corn oil, safflower oil, or DFO (doses ranging from 0.75% to 6.00%) as the fatty acid source for 8 weeks. Mice were gavaged with H. hepaticus; DFO feeding was continued; and mice were sacrificed 4 weeks after infection. The colon and cecum were collected for histopathology. Spleens and mesenteric lymph nodes were collected and analyzed for T-cell populations using flow cytometry. Contrary to expectations, DFO induced severe colitis and adenocarcinoma formation. DFO consumption was associated with decreased CD8(+) cell frequency and diminished CD69 expression on CD4(+) and CD8(+) T-cell populations. Mice consuming DFO also exhibited higher FoxP3(+) CD25(+) CD4(+) T regulatory cell frequency, FoxP3 expression, and altered L-selectin expression during infection. We concluded that DFO-fed mice may be less equipped to mount a successful response to H. hepaticus infection, increasing colon cancer risk. These results support the need to establish a tolerable upper limit for DHA intake particularly in the context of chronic inflammatory conditions such as IBD.
AIM： To characterize the influence of diet-induced changes in body fat on colitis severity in SlVlAD3-/- mice.
METHODS： SMAD3-/- mice （6-8 wk of age） were ran- domly assigned to receive a calorie ...restricted （30% of control; CR）, control （CON）, or high fat （HF） diet for 20 wk and were gavaged with sterile broth or with Helicobacter hepaticus （H. hepaticus） to induce colitis. Four weeks after infection, mice were sacrificed and the cecum and colons were processed for histological evaluation.
RESULTS： Dietary treatment significantly influenced body composition prior to infection （P 〈 0.05）, with CR mice having less （14%±2%） and HF-fed mice more body fat （32% ± 7%） compared to controls （22%±4%）. Differences in body composition were associated with alterations in plasma levels of leptin （HF 〉 CON 〉 CR） and adiponectin （CON 〉 HF 〉/ CR） （P 〈 0.05）. There were no significant differences in colitis scores between CON and HF-fed mice 4 wk post-infection. Consistent with this, differences in proliferation and in- flammation markers （COX-2, iNOS）, and infiltrating cell types （CD3^＋ T lymphocytes, macrophages） were not observed. Unexpectedly, only 40% of CR mice survived infection with H. hepaticus, with mortality observed as early as I wk following induction of colitis.
CONCLUSION： Increased adiposity does not influence colitis severity in SMAD3-/- mice. Importantly, caloric restriction negatively impacts survival following pathogen challenge, potentially due to an impaired immune response.
The gut microbiota plays an essential role in intestinal immunity. Prebiotics, including galacto-oligosaccharides (GOS), are fermentable fibers that beneficially affect the host by stimulating the ...growth of specific microbial populations. We investigated the effect of GOS on colitis development and on immune variables in Smad3-deficient mice treated with the pathogen Helicobacter hepaticus. Mice were supplemented daily with 5000 mg GOS/kg body weight 2 wk prior to infection and 4 wk postinfection, a time period during which colitis severity peaks in this model. Mice (n = 4-8/treatment at each time) were killed preinfection (0 d) and at 3, 7, and 28 d postinfection to evaluate immune variables in the spleen and in mesenteric lymph nodes (MsLN) by flow cytometry. Colon and cecum samples were collected for histopathologic analysis. Fecal pellets (n = 8-9/treatment) were collected prior to infection to measure relative changes in Bifidobacterium ssp. and Lactobacillum ssp. by real-time PCR. GOS significantly reduced colitis severity in response to H. hepaticus (P < 0.0001). This was associated with a significant increase in the percentage of NK cells in the spleen (P < 0.001) and in MsLN (P < 0.001) at 3 d postinfection and a 1.5-fold increase in fecal Bifidobacterium ssp. (P = 0.003). GOS stimulated NK expression of CCR9, a chemokine receptor involved in lymphocyte trafficking to the gut preinfection (0 d) in the blood (P = 0.02), spleen (P = 0.033), and MsLN (P = 0.017). In addition, GOS stimulated colonic IL-15 production 3 d postinfection (P < 0.001). These data suggest that GOS reduces colitis by modulating the function and trafficking of NK cells and may provide a novel therapeutic strategy for individuals with inflammatory bowel disease.
Abstract Diets high in fish and curcumin are associated with a decreased risk of CRC. Insulin resistance and obesity are associated with increased CRC risk and higher reoccurrence rates. We utilized ...cell culture to determine if dietary compounds could reduce insulin-induced cell proliferation comparing the response in normal and metastatic colon epithelial cells. We treated model normal murine colon epithelial cells (YAMC) and adenocarcinoma cells (MC38) with docosahexaenoic acid (DHA) or curcumin alone and then co-treatments of the diet-derived compound and insulin were combined. Cell proliferation was stimulated with insulin (1 ug/mL) to model insulin resistance in obesity. Despite the presence of insulin, proliferation was reduced in the MC38 cells treated with 10 μM curcumin ( p <0.001) and 50 μM DHA ( p <0.001). Insulin stimulated MAPK and MEK phosphorylation was inhibited by DHA and curcumin in MC38 cancer cells. Here we show that curcumin and DHA can block insulin-induced colon cancer cell proliferation in vitro via a MEK mediated mechanism.
AIM： To identify and characterize drosophila mothers against decapentaplegic （SMAD）3-dependent changes in immune cell populations following infection with He- Iicobacter hepaticus （H. hepaticus）. ...METHODS： SMAD3/ （n = L9） and colitis-resistant SMAD3＋/ （n = 24） mice （8-10 wk of age） were in- fected with/-/, hepaticus and changes in immune cell populations T lymphocytes, natural killer （NK） cells, T regulatory cells were measured in the spleen and mesenteric lymph nodes （MsLNs） at 0 d, 3 d, 7 d and 28 d post-infection using flow cytometry. Genotype-dependent changes in T lymphocytes and granzyme B＋ cells were also assessed after 28 d in proximal colon tissue using immunohistochemistry. RESULTS： As previously observed, SMAD3＋, but not SMAD3＋/- mice, developed colitis, peaking at 4 wk post-infection. No significant changes in T cell subsets were observed in the spleen or in the MsLNs between genotypes at any time point. However, CD4＋ and CD8＋/ CD62L＋＋ cells, an effector T lymphocyte population, as well as NK cells （NKp46/DX5＋） were significantly higher in the MsLNs of SMAD3/ mice at 7 d and 28 d post-in- fection. In the colon, a higher number of CD3＋ cells were present in SMAD3＋ compared to SMAD3＋/- mice at base- line, which did not significantly change during infection. However, the number of granzyme B＋ cells, a marker of cytolytic lymphoo/tes, significantly increased in SMAD3＋ mice 28 d post-infection compared to both SMAD3＋/- mice and to baseline values. This was consistent with more severe colitis development in these animals. CONCLUSION： Data suggest that defects in SMAD3 signaling increase susceptibility to H. hepaticus-induced colitis through aberrant activation and/or dysregulation of effector lymphoo/tes.
The gut microbiota plays an essential role in intestinal immunity. Prebiotics, including galacto-oligosaccharides (GOS), are fermentable fibers that beneficially affect the host by stimulating the ...growth of specific microbial populations. We investigated the effect of GOS on colitis development and on immune variables in Smad3-deficient mice treated with the pathogen Helicobacter hepaticus. Mice were supplemented daily with 5000 mg GOS/kg body weight 2 wk prior to infection and 4 wk postinfection, a time period during which colitis severity peaks in this model. Mice (n = 4–8/treatment at each time) were killed preinfection (0 d) and at 3, 7, and 28 d postinfection to evaluate immune variables in the spleen and in mesenteric lymph nodes (MsLN) by flow cytometry. Colon and cecum samples were collected for histopathologic analysis. Fecal pellets (n = 8–9/treatment) were collected prior to infection to measure relative changes in Bifidobacterium ssp. and Lactobacillum ssp. by real-time PCR. GOS significantly reduced colitis severity in response to H. hepaticus (P < 0.0001). This was associated with a significant increase in the percentage of NK cells in the spleen (P < 0.001) and in MsLN (P < 0.001) at 3 d postinfection and a 1.5-fold increase in fecal Bifidobacterium ssp. (P = 0.003). GOS stimulated NK expression of CCR9, a chemokine receptor involved in lymphocyte trafficking to the gut preinfection (0 d) in the blood (P = 0.02), spleen (P = 0.033), and MsLN (P = 0.017). In addition, GOS stimulated colonic IL-15 production 3 d postinfection (P < 0.001). These data suggest that GOS reduces colitis by modulating the function and trafficking of NK cells and may provide a novel therapeutic strategy for individuals with inflammatory bowel disease.
Inflammatory bowel disease (IBD) increases the risk of developing colorectal cancer. It is hypothesized that dietary interventions can reduce inflammation and associated cancer risk. The long chain ...omega‐3 fatty acid, docosahexaenoic acid (DHA) has potent anti‐inflammatory properties. The objective of this study was to determine whether dietary DHA could reduce experimentally induced colitis and subsequent colon cancer risk. We utilized a mouse model of colitis and colon adenocarcinoma formation (SMAD3−/−). When SMAD3−/− mice are exposed to H. hepaticus, colitis is observed 4 wks post infection. Mice (10 per group) were fed AIN‐93G powdered diets supplemented with corn oil, safflower oil, or DHA‐rich fish oil (doses ranging from 0.75–6%) for 8 wks. Mice were then gavaged with H. hepaticus, continued on their diets and sacrificed 4 weeks post‐infection. Colon and cecal tissue were collected for histopathology and scored for inflammation and dysplasia. Spleen, peyers patch and mesenteric lymph nodes were collected for CD3+ cell populations. Contrary to expectations, DHA (2.25–6%) induced severe colitis and adenocarcinoma formation. Increased severity of colitis in DHA fed mice was associated with a CD8+ driven response to bacterial infection. These results suggest that DHA supplementation in immune‐associated diseases like IBD should be approached with caution.
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