Regulatory Activities On Immune System Of Spirulina

Certain species of Spirulina have shown to exhibit immunomodulating and biomod-ulating properties. Studies indicated immunoenhancing properties of S. platensis in animals and humans. Administration of this cyanobacterium has improved immunological resistance in subjects with various types of cancer, viral, and bacterial diseases (Figure 12.5).

It was reported145 that Spirulina up-regulates key cells and organs of the immune system improving their ability to function in spite of stress from environmental toxins and infectious agents. Studies on animal models documented that phycocyanin of Spirulina stimulates hematopoiesis, especially erythropoiesis by inducing erythropoietin hormone (EPO). There is also evidence that c-phcocyanin and polysaccharides of Spirulina enhance white blood cell production 146,147 The percentage of phagocytic macrophages increased when cats were administered water-soluble extract of S. platensis (Qureshi and Ali, 1996). Increased phagocytic activity was also observed in other animals such as mice and chicken 146-148

For example, Lee et al. (2003)149 studied enhancing phagocytic activity of hemo-cytes and disease resistance in the prawn Penaeus merguiensis by feeding S. platensis. Cultured prawns are prone to infectious bacterial diseases, in particular Vibrio spp. 150,151 for they are often subjected to stressful conditions of high stocking density and waste concentration. Enhanced immune resistance to diseases in cultured prawns would be economically desirable. Prawns possess an immune system constituting phagocytic hemocytes and humoral factors;152-154 however, they possess no immunological memory, as they do not have B and T lymphocytes and therefore do not have specific immune responses. Lee et al. (2003) found that exposing the

Spirulina And Immune System

FIGURE 12.5 Effect of Spirulina on Immune system. Spirulina enhance rate of production of RBCs and WBCs by enhancing hematopoiesis. Spirulina also show direct effect on both innate and specific immunity Spirulina activate macrophage and Nk cells. Spirulina induce production of the antibodies. Spirulina also activate of T-cells, B cells and T cells, B and T lymphocytes; CTL, Cytotoxic T lymphocytes; NKcell, Natural Killer cells; L-1, Interleukin-1; Ag, Aggregation; Th, T helper; Tc, cytotoxic T cells (Khan et al., 2005).

FIGURE 12.5 Effect of Spirulina on Immune system. Spirulina enhance rate of production of RBCs and WBCs by enhancing hematopoiesis. Spirulina also show direct effect on both innate and specific immunity Spirulina activate macrophage and Nk cells. Spirulina induce production of the antibodies. Spirulina also activate of T-cells, B cells and T cells, B and T lymphocytes; CTL, Cytotoxic T lymphocytes; NKcell, Natural Killer cells; L-1, Interleukin-1; Ag, Aggregation; Th, T helper; Tc, cytotoxic T cells (Khan et al., 2005).

prawn Penaeus merguiensis to the bacteria Vibrio harveyi and E. coli for an hour or feeding the prawns with S. (Arthrospira) platensis (0.3% w/w feed) enhanced the phagocytic activity of their hemocytes. Improvement of the phagocytic activity was primarily through the activation of the hemocytes. Furthermore, the activated phagocytic hemocytes had a higher capacity to engulf foreign agents, such as bacteria, and a higher rate of phagocytosis. The phagocytic enhancement effect peaked on the fourth day of feeding with Spirulina. In the in vitro study, the granular cells from prawns took 45-60 min to complete the process of degranulation. Preexposure to Salmonella typhimurium and Bacillus subtilis did not result in enhancement of phagocytic activity of hemocytes. Only 10% of the prawns fed with Spirulina died in the first 14 days when challenged by V harveyi at a concentration of 1 x 104 CFUs mL-1, while all control prawns (basal feed without Spirulina) died within 14 days.

Duncan and Klesius (1996)155 have reported that Spirulina are also capable of enhancing nonspecific immune responses in fish. They demonstrated that peritoneal phagocytes from channel catfish (I. punctatus) fed S. plantesis, showed enhanced phagocytosis to zymosan and increased chemotaxis to Edwardsiella ictaluri exoantigen. In mice, Spirulina facilitated antibody production, increased the ratio of activated peritoneal macrophages, and induced spleen cells to grow better in response to Con A.137 (Hirahashi, T. et al., 2002). Hayashi et al. (1994, 1998)156,157 reported that Spirulina and its extracts enhanced immune responses in mice, mainly through increased production of interleukin-1(IL-1) in macrophages. They investigated antibody productions of IgA and other classes, such as IgE and IgG1, in mice as possible evidence of the protective effects of Spirulina toward food allergy and micro-bial infection. An increase of IgE antibody level in the serum was observed in the mice that were orally immunized with crude shrimp extract as an antigen (Ag group). The antibody level; however, was not further enhanced by treatment with Spirulina extract (SpHW). IgG1 antibody, on the other hand, which was increased by antigen administration, was further enhanced by Spirulina extract. It was noted that the ISA antibody level in the intestinal contents was significantly enhanced by treatment with Spirulina extract concurrently ingested with shrimp antigen, in comparison with that of the Ag group treated with shrimp antigen alone. It was reported that intraperi-toneally injected polysaccharides of a hot-water extract of Spirulina increased the percentage of peritoneal phagocytic cells besides increasing the hemolysin contents in the blood of mice.158

Watanuki et al., 2006, studied immunostimulant effects of dietary S. platensis on carp, Cyprinus carpi. For this purpose, fish were fed with Spirulina and the parameters of non-specific defence mechanisms, including phagocytosis and production of superoxide anion were performed at 1, 3, and 5 days after Spirulina administration. The results demonstrated that Spirulina enhanced responses of phagocytic activity and superoxide anion production in kidney phagocytic cells. This activation of kidney cells was observed for at least 5 days post treatment. The expression of interleukin (IL)-1^ and tumor necrosis factor (TNF)-a genes also increased in fish treated with Spirulina. On the other hand, the expression of IL-10 gene was decreased. Furthermore, the numbers of Aeromonas hydrophila were decreased in the liver and kidney of Spirulina-treated fish. The numbers of bacteria were lowed in the liver and kidney of carp treated with Spirulina than the control group. Sakai et al. (1993)159 reported that fish treated with lactoferrin immediately decreased the number of bacteria in the blood, the kidney and the liver after artificial bacterial challenge and this elimination relates to the resistance of fish to these challenge pathogens. Thus, this result demonstrates the increased resistance to A. hydrophila infection on carp treated with Spirulina. This study indicate that oral administration of Spirulina to carp leads to (a) enhanced phagocytic activity and superoxide anion production by phagocytic cells, (b) augmented the expression of IL-1^ and TNF-a genes in the kidney leucocytes, and (c) increased resistance against A. hydrophila infection.160

Recently, Liu et al. (2000)161 reported that phycocyanin, a characteristic photosynthesis pigment protein in Spirulina, inhibited growth of human leukemia K562 cells and enhanced the arrest of the cell growth at G1 phase, suggesting enhancement of differentiation of the cells. Hayashi et al. (2006)162 investigated effects of Spirulina and its extracts on the introduction of colony stimulating factor(s) and on their proliferation and differentiation activity for hematopoietic cells in mice. They show that the Spirulina extracts, phycocyanin, hot-water extract, phycocyanin, and cell-wall component extract, enhanced proliferation of bone-marrow cells and induced colony-forming activity in the spleen-cell culture supernatant. These findings suggest that Spirulina,and its components such as phycocyanin, affects immune functions by promoting immune component cell proliferation or differentiation in lymphoids.

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