Aerosol 1,25-dihydroxyvitamin D3 supplementation: A strategy to boost anti-tumor innate immune activity.

BACKGROUND: 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] plays a role in calcium homeostasis but can also exert immunomodulatory effects. In lungs, characterized by a particular immunosuppressive environment primarily due to the presence of alveolar macrophages (AM), 1,25(OH)2D3 has been shown to favor the immune response against pathogens. Here, we explored the ability of aerosolized 1,25(OH)2D3 to locally promote an anti-tumor phenotype in alveolar macrophages (AM) in the treatment of lung metastases. METHODS: Cytotoxicity assay has been used to assess the capability of AM, in vitro treated of not with 1,25(OH)2D3, to stimulate NK cells. Sulforhodamine B (SRB) assay has been used to assess the effect of 1,25(OH)2D3 on MC-38 and B16 tumor cells in vitro growth. 1,25(OH)2D3 was aerosolized in immunocompetent mouse models to evaluate the effect of local administration of 1,25(OH)2D3 on in vivo growth of MC-38 and B16 tumor cells within lungs and on infiltrating immune cells. RESULTS: In vitro incubation of naïve AM with 1,25(OH)2D3 improved their ability to stimulate NK cell cytotoxicity. In vivo aerosolized 1,25(OH)2D3 significantly reduced the metastatic growth of MC-38 colon carcinoma, a tumor histotype that frequently metastasizes to lung in human. Immune infiltrate obtained from digested lungs of 1,25(OH)2D3-treated mice bearing MC-38 metastases revealed an increased expression of MHCII and CD80 on AM and an up-modulation of CD69 expression on effector cells that paralleled a strong increased ability of these cells to kill MC-38 tumor in vitro. CONCLUSIONS: Together, these data show that aerosol delivery can represent a feasible and novel approach to supplement 1,25(OH)2D3 directly to the lungs promoting the activation of local immunity against cancer.

Influence of lignans depletion on murine mammary gland morphology.

Different studies have focused on the effects of phytoestrogens-supplemented diets on mammary gland morphogenesis and breast cancer risk; however, particular dieting behaviors and food choices may result in a reduction of the natural source of phytoestrogens. The evaluation of a reduced phytoestrogens intake effect by depletion without modifying other dietary ingredients is hard. Since lignans, the largest contributors to phytoestrogens intake in Western diets, are metabolized into bioactive compounds by gut bacteria, long-term antibiotic treatments, inducing intestinal microflora disruption, may reduce enterolactone availability. To elucidate the effect of phytoestrogens lack on mammary tissue morphogenesis, female FVB mice were treated with gentamicin or metronidazole/ciprofloxacin from the age of 6 to 7 wk. After 21 wk, enterolactone urine levels were 120.07 +/- 20.5 ng/ml in untreated mice, 30.4 +/- 24.46 ng/ml in metronidazole/ciprofloxacin-treated mice, and 3.29 +/- 4.38 ng/ml in gentamicin-treated mice. Histological analysis revealed no significant alterations of mammary morphology in metronidazole/ciprofloxacin-treated mice, whereas gentamicin-treated mice showed increase of ducts number and duct-tree branching vs. controls. These findings indicate that normal mammary tissue size and shape are maintained even in the presence of low levels of lignans and suggest that only a complete depletion of these compounds induced significant alterations of mammary gland structure.

Influence of antibiotic treatment on breast carcinoma development in proto-neu transgenic mice.

The effect of prolonged antibiotic treatments on tumor development was evaluated in proto-neu transgenic mice, which spontaneously develop mammary carcinomas. Virgin transgenic mice were treated with metronidazole/ciprofloxacin or gentamicin through the drinking water. The hazard ratio [HR; 95% confidence interval (95% CI)] of breast cancer occurrence in metronidazole/ciprofloxacin-treated mice was more than triple that for controls [3.11 (1.13-8.53); P = 0.028], whereas only a slight increase in HR (95% CI) was observed in gentamicin-treated mice [1.39 (0.56-3.47); P = 0.481]. Tumor growth rate in gentamicin-treated mice was significantly faster than in untreated control mice (P = 0.043). Moreover, mammary glands from mice treated with either antibiotic regimen showed increased lobulization, with more numerous and more developed terminal ductal lobular units than in controls. These results indicate that prolonged exposure to relevant doses of antibiotics affects the mammary glands in this particular model of HER-2/neu transgenic mice; further studies to understand the precise mechanism by which antibiotic treatments influence mammary gland differentiation are critical.