Dietary Chlorella vulgaris Ameliorates Altered Immunomodulatory Functions in Cyclophosphamide-Induced Immunosuppressive Mice

Abstract

Based on the well-known toxicity of cyclophosphamide (CYP) on the immune system, this research investigated the modulating effects of the long-term dietary Chlorella vulgaris (CV) supplementation on the immunosuppression induced by CYP in mice, in order to provide a novel dietary design to mitigate the side effects of CYP therapy. Control, CYP-treated, CYP + CV (6%), CYP + CV (12%) and CYP + CV (24%) were used for 6 weeks, CV supplement in diet recovered the significantly reduced immunological function in CYP treated mice. As CV may have a modulating function through the inducible expression of cytokines, we assayed the expressions of interleukin-2 (IL-2), interleukin-12 (IL-12), tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ). Our results suggested that CYP significantly reduced the lymphocytes proliferation and phagocytic activities of macrophages, and stimulated the production of IL-2, IL-12, TNF-α and IFN-γ and that this impairment has been successfully adjusted by CV supplementation. Treatment with the algae also enhanced the natural killer (NK) cells cytotoxicity, and ameliorate histological changes of the spleen in CYP-treated mice. Therefore, as we found in this study, a diet supplemented with whole CV has beneficial effects on CVP-induced immunosuppression, through its immunomodulatory potential.

Keywords: Chlorella vulgaris; cyclophosphamide; diet; immunosuppressive mice.

Figure 1

Effect of Chlorella vulgaris (CV) on the spleen index (A), thymus index (B), the relative activity of lactate dehydrogenase (LDH) (C), acid phosphatase (ACP) (D), splenocyte proliferation added with concanavalinA (ConA) (E) and lipopolysaccharide (LPS) (F) in the cyclophosphamide (CYP)-treated mice. Note: Data were expressed as mean ± standard deviation (SD), *: only the CYP treatment was compared against the control treatment (p < 0.05); #: only the CYP + CV treatment was compared against the CYP treatment (p < 0.05), ##: only the CYP + CV treatment was compared against the CYP treatment (p < 0.01).

Figure 2

Effect of CV on the natural killer (NK) cell cytotoxicity in the CYP-treated mice. Note: Data were expressed as mean ± SD, *: only the CYP treatment was compared against the control treatment (p < 0.05); #: only the CYP + CV treatment was compared against the CYP treatment (p < 0.05), ##: only the CYP + CV treatment was compared against the CYP treatment (p < 0.01).

Figure 3

Photomicrograph of spleen from each experimental group (magnification = 100×). (A), control group, normal diet, showing the absence of damage of spleen tissue; Compared with the control, the CYP group (B) showed evident necrosis region (N), cellular fibrosis (F) and disordered arrangement of cells (DA). In the CV (6%) group (C), the necrosis region became minor and the intercellular space was lessened as compared with the CYP group. The CV (12%) group (D) and CV (24%) group (E) had unbroken cell, and fibrosis cells became smaller.

Figure 4

Effects of CV on proliferation (A) and phagocytosis activity (B) of peritoneal macrophages in CYP-treated mice. Note: Data were expressed as mean ± SD, *: only the CYP treatment was compared against the control treatment (p < 0.05); #: only the CYP + CV treatment was compared against the CYP treatment (p < 0.05), ##: only the CYP + CV treatment was compared against the CYP treatment (p < 0.01).

Figure 5

Effects of CV on the mRNA expression levels of IL-2 (A), IL-12 (B), TNF-α (C) and IFN-γ (D) in the spleen of CYP-treated mice. The β-actin was used as the control. Note: Data were expressed as mean ± SD, *: only the CYP treatment was compared against the control treatment (p < 0.05); #: only the CYP + CV treatment was compared against the CYP treatment (p < 0.05), ##: only the CYP + CV treatment was compared against the CYP treatment (p < 0.01).

Figure 6

Effects of CV on the level of IL-2 (A), IL-12 (B), TNF-α (C) and IFN-γ (D) proteins in the spleen of CYP-treated mice. The β-actin was used as the control. Note: Data were expressed as mean ± SD, *: only the CYP treatment was compared against the control treatment (p < 0.05); #: only the CYP + CV treatment was compared against the CYP treatment (p < 0.05), ##: only the CYP + CV treatment was compared against the CYP treatment (p < 0.01).