The effects of Chlorella vulgaris in the protection of mice infected with Listeria monocytogenes. Role of natural killer cells

Beneficial immunostimulatory effect of short-term Chlorella supplementation: enhancement of natural killer cell activity and early inflammatory response (randomized, double-blinded, placebo-controlled trial)

BACKGROUND

In vitro and animal studies have demonstrated that Chlorella is a potent biological response modifier on immunity. However, there were no direct evidences for the effect of Chlorella supplementation on immune/inflammation response in healthy humans.

METHODS

This study was designed for an 8-week randomized, double-blinded, placebo-controlled trial: 5g of Chlorella (n=23) or Placebo (n=28) as form of tablets. Mainly, cytotoxic activities of Natural killer (NK) cells and serum concentrations of interferon-γ, interleukin-1β and interleukin-12 were measured.

RESULTS

After the 8-week, serum concentrations of interferon-γ (p<0.05) and interleukin-1β (p<0.001) significantly increased and that of interleukin-12 (p<0.1) tended to increase in the Chlorella group. The increments of these cytokines after the intervention were significantly bigger in the Chlorella group than those in the placebo group. In addition, NK cell activities (%) were significantly increased in Chlorella group, but not in Placebo group. The increments of NK cell activities (%) were also significantly bigger in the Chlorella group than the placebo group. Additionally, changed levels of NK cell activity were positively correlated with those of serum interleukin-1β (r=0.280, p=0.047) and interferon-γ (r=0.271, p<0.005). Signficantly positive correlations were also observed among the changed levels of serum cytokines; between interferon-γ and interleukin-1β (r=0.448, p<0.001), between interleukin-12 and interleukin-1β (r=0.416, p=0.003) and between interleukin-12 and interferon-γ (r=0.570, p<001).

CONCLUSION

These results may suggest a beneficial immunostimulatory effect of short-term Chlorella supplementation which enhances the NK cell activity and produces interferon-γ and interleukin-12 as well as interleukin-1β, the Th-1 cell-induced cytokines in healthy people.

Alkali-soluble polysaccharides of Rhizoclonium riparium alga induce IL-1 gene expression via protein kinase signaling pathways

Fortification of aquaculture foodstuff with various algae may improve the resistance of certain fish or shrimp to diseases and, as a routine procedure, has become ever more popular and, seemingly, important. Herein, we isolated certain alkali-soluble polysaccharides from a Rhizoclonium riparium alga (RASP), polysaccharides that can be separated into two different groups on the basis of the polysaccharide's molecular weight. Using gas chromatography-mass spectometry analysis, we found that the major monosaccharides constituting the higher molecular-weight group of RASP were galactose (41.99%), glucose (34.53%), xylose (20.24%), and mannose (3.24%). Using a murine-derived macrophage cell line J774A.1, we found that polysaccharide constituents of the higher molecular-weight group of RASP were able to induce interleukin-1beta (IL-1) gene expression via protein kinase-mediated signal transduction pathways. In essence, we found that c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (p38), but not extracellular signal-regulated kinase (ERK), play an important role in the regulation of IL-1 gene expression in RASP-stimulated J774A.1 cells. To the best of our knowledge, this is the first occasion that polysaccharides from R. riparium have been demonstrated to exert immunomodulation properties by the induction of IL-1 within macrophages. Our current results provide support for the possible use of R. riparium as an additive to various food/foodstuff, to modulate the immune response of humans or certain animals.

Effects of Chlorella vulgaris extract on cytokines production in Listeria monocytogenes infected mice

In this study, we have investigated the effects of the unicellular-green-algae Chlorella vulgaris on the production of INF-gamma, IL-2, IL-4 and IL-10 in normal and Listeria monocytogenes infected mice. Our results demonstrated that in normal/non infected mice, CVE administration produced no effects in the levels of all cytokines studied. However, Listeria monocytogenes infection enhanced the production of INF-gamma and IL-2 at 48 and 72 h after the bacteria inoculation. Interestingly, the treatment with five consecutive doses of 50 mg/Kg/day of Chlorella vulgaris given previously to infection, led to further increases in INF-gamma and IL-2 levels at 48 and 72 h in relation to the presence of infection alone. No changes in IL-4 and IL-10 production were observed in Listeria monocytogenes and CVE treated/infected mice. These results are in accordance with the literature, which shows that CVE is a biological response modifier that enhances resistance to Listeria monocytogenes through augmentation of IL-2 and IFN-gamma.

Evaluation of Caesalpinia ferrea extract on bone marrow hematopoiesis in the murine models of listeriosis and Ehrlich ascites tumor

The capacity of hematopoietic tissues to produce and mobilize phagocytes to the site of infection and tumor growth is of central importance to mediate the early immunological response. In this perspective, studies from our laboratory have defined Listeria monocytogenes infection and the Ehrlich ascites tumor (EAT) as useful models to investigate the effects of natural compounds on the growth and differentiation of granulocyte-macrophage progenitor cells (CFU-GM). As expected, a significant reduction in the number of bone marrow CFU-GM was observed in the initial stages of infection with a sublethal dose of Listeria. Similarly, the bone marrow CFU-GM decreased sharply 4 days after the EAT transplantation. Treatment of infected and tumor-bearing mice with 500 and 1,000 mg/kg of Caesalpinia ferrea aqueous extract, given 3 times orally, significantly stimulated myelopoiesis, whereas no effects were observed with the 250 mg/kg dose. Similar results were obtained in normal mice. The administration of the two higher doses of the extract also protected 15-20% of mice from a lethal dose of Listeria and significantly prolonged survival of EAT-bearing mice. In summary, these results demonstrate that C. ferrea extract acts as a positive regulator of myelopoiesis, and suggest that the therapeutic effect of C. ferrea may be partially mediated by this action.

Effects of the green algae Chlorella vulgaris on the response of the host hematopoietic system to intraperitoneal ehrlich ascites tumor transplantation in mice

Chlorella vulgaris extract (CVE) was examined for its effects on the Ehrlich ascites tumor-induced suppression in the numbers of bone marrow and spleen granulocyte-macrophage progenitor cells (CFU-GM) in mice. No effects on bone marrow and spleen CFU-GM, as compared to controls, were observed in normal mice given 50, 100 and 200 mg/kg CVE orally for 5 days. In tumor-bearing mice, myelosuppression concomitant with increased number of spleen CFU-GM were observed. The number of CFU-GM in the bone marrow was restored to control levels after the administration of CVE (50, 100 and 200 mg/kg) to tumor-bearing mice, and a slight reduction in spleen colony formation was observed in these animals. In addition, CVE significantly prolonged the survival of mice inoculated with the Ehrlich ascites tumor. These results suggest a protective antitumor effect of CVE which might be attributable, at least in part, to the stimulation of the production and, possibly, maturation of granulocytes and macrophages.

Stimulatory action of Pluchea quitoc extract on the hematopoietic response during murine listeriosis

The importance of both granulocytes and macrophages in the response to Listeria monocytogenes infection make this infection a suitable choice to investigate the effects of Pluchea quitoc on hematopoiesis. A significant depletion of bone marrow granulocyte-macrophage progenitor cells (CFU-GM) was observed at 48 and 72 h after intraperitoneal infection of mice with 1 x 10(4) L. monocytogenes. However, the treatment of infected animals with P. quitoc ethanolic extract (250, 500 or 1000 mg/kg) given orally for 3 consecutive days prior to infection produced a stimulatory effect on myelopoiesis, restoring the number of CFU-GM to normal. This same dose-schedule also increased colony formation in normal mice as compared to controls. In addition, P. quitoc significantly enhanced survival of infected mice. Thus, it is probable that the ability of P. quitoc to induce a higher reserve of granulocyte-macrophage precursors in the bone marrow is of major significance in determining early resistance to infection.