Immolina,a High–Molecular-Weight Polysaccharide Fraction of Spirulina,Enhances Chemokine Expression in Human Monocytic THP-1 Cells

Abstract

Introduction

: Spirulina (Spirulina platensis) is a dietary supplement valued for its immune-enhancing properties. We previously reported that the immunostimulatory effect of spirulina can be traced to a high–molecular- weight polysaccharide fraction. This fraction, labeled Immolina, activates nuclear factor kappa–B in human monocytic THP-1 cells and increases expression of proinflammatory cytokines.

Objective

: To characterize further the immunostimulatory effects of Immolina on THP-1 cells, we evaluated its effect on genes encoding the chemokines interleukin (IL)–8, MCP-1, MIP-1α, MIP-1β, IP-10, the cytokines tumor necrosis factor (TNF)–α, IL-1β, and the enzyme cyclo-oxygenase-2 (COX-2).

Methods

: THP-1 cells were exposed to concentrations of Immolina ranging from 1 ng/mL to 100 µg/mL and changes in gene expression were assessed by reverse transcriptase–polymerase chain reaction (RT-PCR). For comparison, THP-1 cells were activated with 1 ng/mL of TNF-α, 10 ng/mL of IL-1β, or 10 ng/mL of lipopolysaccharide using the same assay conditions. To assess the response of THP-1 cells to Immolina at the protein level, we probed culture supernatants using a cytokine array immunoblot assay.

Results

: RT-PCR analysis revealed that Immolina dose-dependently increased the expression of all 5 chemokines tested as well as the expression of TNF-α, IL-1β, and COX-2. The cytokine array immunoblot assay revealed an increase in the chemokines IL-8 and MIP-1β. Thymidine uptake experiments verified that Immolina did not affect the viability and growth rate of THP-1 cells.

Conclusions

: The results of the experiments demonstrate that Immolina activates THP-1 cells in a manner that is consistent with the recruitment of diverse populations of leukocytes in response to inflammatory and infectious signals.