Immunomodulatory and Antioxidant Effects of Purple Sweet Potato Extract in LP-BM5 Murine Leukemia Virus-Induced Murine Acquired Immune Deficiency Syndrome.

The immunomodulatory effects of a dietary supplement of purple sweet potato extract (PSPE) in LP-BM5 murine leukemia virus (MuLV)-induced immune-deficient mice were investigated. Mice were divided into six groups: normal control, infected control (LP-BM5 MuLV infection), positive control (LP-BM5 MuLV infection+dietary supplement of red ginseng 300 mg/kg), purple sweet potato water extract (PSPWE) (LP-BM5 MuLV infection+dietary supplement of PSPE 300 mg/kg), PSP10EE (LP-BM5 MuLV infection+dietary supplement of 10% ethanol PSPE 300 mg/kg), and PSP80EE (LP-BM5 MuLV infection+dietary supplement of 80% ethanol PSPE 300 mg/kg). Dietary supplementation began on the day of LP-BM5 MuLV infection and continued for 12 weeks. Dietary supplementation of PSPE inhibited LP-BM5 MuLV-induced splenomegaly and lymphadenopathy and attenuated the suppression of T- and B-cell proliferation and T helper 1/T helper 2 cytokine imbalance in LP-BM5 MuLV-infected mice. Dietary supplement of PSPE increased the activity of the antioxidant enzymes, superoxide dismutase and glutathione peroxidase. The data suggest that PSPE may ameliorate immune dysfunction due to LP-BM5 MuLV infection by modulating antioxidant defense systems.

Effects of fish oil on cytokines and immune functions of mice with murine AIDS.

The effects of fish oil, which is rich in n-3 fatty acids, on cytokine levels in a murine model of acquired immune deficiency syndrome (AIDS) were studied. Thirty-two C57BL/6 female mice were divided into two dietary groups and fed either a corn oil diet or a fish oil diet. After 4 weeks, each diet group was further divided into two subgroups, and mice in one subgroup were injected i.p. with LP-BM5 murine retrovirus (MAIDS) stock. After 4 weeks, all mice were killed, blood samples were collected, and the spleens and the livers were excised. Splenocytes were isolated immediately and cultured in RPMI-1640 medium and stimulated by either lipopolysaccharide (LPS) or Concanavalin A (ConA) for 24 h. The supernatant was collected for cytokine assays. The results showed that MAIDS infection increased the levels of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1-beta (IL-1beta), while fish oil partially prevented this elevation. MAIDS infection depressed interleukin-2 (IL-2) and interferon-gamma (IFNgamma), while fish oil partially prevented the depression of IL-2. In addition, MAIDS infection depressed LPS- and ConA-stimulated cell proliferation, while fish oil partially prevented the depression. The results suggest that fish oil may slow down the progression of murine AIDS by modulating levels of cytokines including TNF-alpha, IL-1beta, and IL-2.

Vitamin E supplementation modulates cytokine production by thymocytes during murine AIDS.

Female C57BL/6 mice were infected with LP-BM5 retrovirus, causing murine AIDS, which is functionally similar to human AIDS. Retrovirus infection targeted the thymus, producing altered T cell differentiation via the dysregulation of thymocyte cytokine production. Human AIDS causes vitamin deficiencies, therefore the effects of dietary vitamin E supplementation were determined on the kinetics of cytokine production by concanavalin A-stimulated thymocytes in uninfected normal mice and mice with murine AIDS. Dietary supplementation, with a 15-fold increase in vitamin E (160 IU/l) in the liquid diet (National Research Council), modulated interleukin-2 (IL) production in both uninfected mice and retrovirus-infected mice. Vitamin E significantly reduced the level of IL-4 secretion in the uninfected mice at 4 and 8 weeks, but not at 12 and 16 weeks. It also significantly reduced IL-4 production, elevated by retrovirus infection. Vitamin E significantly reduced IL-6, and interferon-gamma production increased in murine AIDS. The effects of dietary vitamin E on concanavalin A-induced proliferation of thymocytes were consistent with the finding of changes in IL-2 secretion. No effects of dietary vitamin E on thymus weight were observed in uninfected or retrovirus-infected mice, whereas vitamin E significantly increased serum and thymic vitamin E concentration, which had been reduced by retrovirus infection. These data indicate that dietary vitamin E supplementation can modulate cytokine production by thymocytes, affecting T cell differentiation, especially during retrovirus-induced immune dysfunction.

Potential of diet therapy on murine AIDS.

Recently, a murine retrovirus (LpBM5 MuLV), which induces immunodeficiency syndrome in mice, termed MAIDS, has been found to have several features similar to those seen in human acquired immunodeficiency syndrome (AIDS). The present study was undertaken to compare the effects of 40% energy restriction (R) and/or ad libitum (AL) diets with vegetable [corn oil, (CO) (n-6)] or marine oil [menhaden fish oil (FO), (n-3)] as a source of dietary fats on the immune function and survival rate of C57BL/6 mice injected with the LpBM5 MuLV virus. Weanling mice were fed, throughout the study, either a 5% CO-, 5% CO(R)-, 20% CO- or 20% FO-based diet and 8 wk later the mice were injected with the LpBM5 MuLV (5 x 10(5) plaque-forming units). The results revealed a significantly prolonged postinjected survival rate in the mice fed 20% FO and 5% CO(R) diets [5% CO = 131 +/- 7 d; 5% CO(R) = 161 +/- 13 d; 20% CO = 125 +/- 6 d; 20% FO = 164 +/- 14 d]. Immunological studies conducted 4 wk after injection revealed decline in both interleukin-2 production and proliferative response to mitogens in spleen cells of mice in all four dietary groups. However, this decline was less apparent in mice fed 5% CO(R) and 20% FO diets.(ABSTRACT TRUNCATED AT 250 WORDS)