Objectives: Children with autism spectrum disorder (ASD) frequently reveal various gastrointestinal (GI) symptoms that may resolve with an elimination diet along with apparent improvement of some of the behavioral symptoms. Evidence suggests that ASD may be accompanied by aberrant (inflammatory) innate immune responses. This may predispose ASD children to sensitization to common dietary proteins (DP), leading to GI inflammation and aggravation of some behavioral symptoms. Methods: We measured IFN-γ, IL-5, and TNF-α production against representative DPs [gliadin, cow’s milk protein (CMP), and soy] by peripheral blood mononuclear cells (PBMCs) from ASD and control children [those with DP intolerance (DPI), ASD siblings, and healthy unrelated children]. We evaluated the results in association with proinflammatory and counter-regulatory cytokine production with endotoxin (LPS), a microbial product of intestinal flora and a surrogate stimulant for innate immune responses. Results: ASD PBMCs produced elevated IFN-γ and TNF-α, but not IL-5 with common DPs at high frequency as observed in DPI PBMCs. ASD PBMCs revealed increased proinflammatory cytokine responses with LPS at high frequency with positive correlation between proinflammatory cytokine production with LPS and IFN-γ and TNF-α production against DPs. Such correlation was less evident in DPI PBMCs. Conclusion: Immune reactivity to DPs may be associated with apparent DPI and GI inflammation in ASD children that may be partly associated with aberrant innate immune response against endotoxin, a product of the gut bacteria.
Astaxanthin, a carotenoid without vitamin A activity, may exert antitumor activity through the enhancement of immune responses. Here, we determined the effects of dietary astaxanthin on tumor growth and tumor immunity against transplantable methylcholanthrene-induced fibrosarcoma (Meth-A tumor) cells. These tumor cells express a tumor antigen that induces T cell-mediated immune responses in syngenic mice. BALB/c mice were fed astaxanthin (0.02%, 40 micrograms/kg body wt/day in a beadlet form) mixed in a chemically defined diet starting zero, one, and three weeks before subcutaneous inoculation with tumor cells (3 x 10(5) cells, 2 times the minimal tumorigenic dose). Three weeks after inoculation, tumor size and weight were determined. We also determined cytotoxic T lymphocyte (CTL) activity and interferon-gamma (IFN-gamma) production by tumor-draining lymph node (TDLN) and spleen cells by restimulating cells with Meth-A tumor cells in culture. The astaxanthin-fed mice had significantly lower tumor size and weight than controls when supplementation was started one and three weeks before tumor inoculation. This antitumor activity was paralleled with higher CTL activity and IFN-gamma production by TDLN and spleen cells in the astaxanthin-fed mice. CTL activity by TDLN cells was highest in mice fed astaxanthin for three weeks before inoculation. When the astaxanthin-supplemented diet was started at the same time as tumor inoculation, none of these parameters were altered by dietary astaxanthin, except IFN-gamma production by spleen cells. Total serum astaxanthin concentrations were approximately 1.2 mumol/l when mice were fed astaxanthin (0.02%) for four weeks and appeared to increase in correlation with the length of astaxanthin supplementation. Our results indicate that dietary astaxanthin suppressed Meth-A tumor cell growth and stimulated immunity against Meth-A tumor antigen.
The effect of carotenoids on in vitro immunoglobulin (Ig) production by peripheral blood mononuclear cells (PBMNC) was examined by employing blood samples from adult volunteers and full-term newborn babies (umbilical cord blood). Under carotenoid-supplemented culture conditions, cells were stimulated by polyclonal stimulants, neoantigens, and a recall antigen (Ag), and IgM, IgA, and IgG levels in the culture supernatant were measured. Beta-carotene and astaxanthin were used as representatives of carotenoids with and without vitamin A activity, respectively. Astaxanthin enhanced IgM production in response to T-dependent Ag (TD-Ag) and a T-dependent polyclonal stimulant. Astaxanthin also augmented IgG production in response to a recall Ag. IgA production without supplemental carotenoids was negligible for all stimuli. However, in carotenoid-supplemented cultures, IgA production was significantly higher in response to a T-dependent polyclonal stimulant than in unsupplemented cultures. IgM and IgA production was augmented at 10(-8) mol/l astaxanthin, whereas astaxanthin enhanced IgG production in response to a recall Ag at 10(-10)-10(-9) mol/l. Similar enhancing actions of astaxanthin on IgM production were observed in cord blood mononuclear cells (CBMNC), although CBMNC produced less IgM than adult PBMNC. Beta-carotene did not have a significant effect on human Ig production. The carotenoid actions were not demonstrated under serum-free culture conditions; serum is essential for solubilization of carotenoids. In summary, this study has shown for the first time that astaxanthin, a carotenoid without vitamin A activity, enhances human Ig production in response to T-dependent stimuli.
Previously it was reported that hyperoxia induced death of the human lung adenocarcinoma cell line (A549 cells) by necrosis, not by apoptosis. This study examined proliferation and death of untransformed human small airway epithelial (SAE) cells in normoxia or hyperoxia in comparison with A549 cells. We tested the hypothesis that SAE cells respond differently to hyperoxic injury than do A549 cells. We measured total cell number and viability, thymidine incorporation (SAE cells only), lactate dehydrogenase (LDH) release, and apoptotic changes as markers for cell proliferation and death. Protective effects of antioxidant vitamins also were examined in SAE cells. In normoxia, subconfluent SAE cells had less apoptosis and fewer detached cells, but higher thymidine incorporation than did near-confluent cells. Hyperoxia suppressed thymidine incorporation and augmented apoptosis in both subconfluent and near-confluent SAE cells. Hyperoxia decreased the total cell number only in subconfluence, whereas SAE cell viability declined with hyperoxia in near confluence, but not in subconfluence. For SAE cells, necrosis assessed by LDH release was minimal in all conditions and was not augmented by hyperoxia in SAE cells. In contrast, normoxic A549 cells proliferated more rapidly than did SAE cells with a large number of cells detached during the culture. A549 cells underwent necrotic cell death under confluent or in hyperoxic conditions, but had much less apoptotic cell death. In SAE cells, vitamin E partially prevented the decline of thymidine incorporation with hyperoxia in subconfluence and protected against apoptotic changes with hyperoxia in both subconfluent and near-confluent conditions. Vitamin C prevented apoptosis with hyperoxia only in near-confluent SAE cells. Thus, SAE cells maintained balanced apoptosis and cell proliferation that were altered by cell density and hyperoxia and demonstrated very little necrosis with hyperoxia. Although A549 cells underwent cell death mainly by necrosis, they also were influenced by cell density and hyperoxia. Cell density also determined specific antioxidant vitamin protection in SAE cells.
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