Immunomodulatory activity of polysaccharides isolated from Clerodendrum splendens: Beneficial effects in experimental autoimmune encephalomyelitis

Abstract

BackgroundExtracts of leaves from Clerodendrum have been used for centuries to treat a variety of medicinal problems in tropical Africa. However, little is known about the high-molecular weight active components conferring therapeutic properties to these extracts.MethodsPolysaccharides from the leaves of Clerodendrum splendens were extracted and fractionated by ion exchange and size-exclusion chromatography. Molecular weight determination, sugar analysis, degree of methyl esterification, and other chemical characterization of the fractions were performed. Immunomodulatory activity of the fractions was evaluated by determining their ability to induce monocyte/macrophage nitric oxide (NO), cytokine production, and mitogen-activated protein kinase (MAPK) phosphorylation. Experimental autoimmune encephalomyelitis (EAE) was induced in C57BL/6 mice, and severity of EAE was monitored in mice treated with intraperitoneal (i.p.) injections of the most active polysaccharide fraction. Lymph nodes (LN) and spleen were harvested, and levels of cytokines in supernatants from LN cells and splenocytes challenged with myelin oligodendrocyte glycoprotein peptide were determined.ResultsFractions containing type II arabinogalactan had potent immunomodulatory activity. Specifically, the high-molecular weight sub-fraction CSP-AU1 (average of 38.5 kDa) induced NO and cytokine [interleukin (IL)-1α, -1β, -6, -10, tumor necrosis factor (TNF; designated previously as TNF-α), and granulocyte macrophage-colony stimulating factor (GM-CSF)] production by human peripheral blood mononuclear cells (PBMCs) and monocyte/macrophages. CSP-AU1-induced secretion of TNF was prevented by Toll-like receptor 4 (TLR4) antagonist LPS-RS, indicating a role for TLR4 signaling. Treatment with CSP-AU1 also induced phosphorylation of a number of MAPKs in human PBMC and activated AP-1/NF-κB. In vivo treatment of mice with CSP-AU1 and CSP-NU1 resulted in increased serum IL-6, IL-10, TNF, monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory protein (MIP)-1α/CCL3, and MIP-1β/CCL4. CSP-AU1 treatment of mice with EAE (50 mg/kg, i.p., daily, 13 days) resulted in significantly reduced disease severity in this experimental model of multiple sclerosis. Levels of IL-13, TNF, interferon (IFN)-γ, IL-17, and GM-CSF were also significantly decreased, whereas transforming growth factor (TGF)-β was increased in LN cells from CSP-AU1-treated EAE mice.ConclusionsPolysaccharide CSP-AU1 is a potent natural innate immunomodulator with a broad spectrum of agonist activity in vitro and immunosupressive properties after chronic administration in vivo.

Genetic Transformation for Quality Improvement in Ornamental Climbers

“…These results demonstrated that polysaccharide subfraction CSP-AU1, isolated from the Clerodendrum , was one of the most effective activators of cytokine production and activates monocyte/macrophages through the signalling cascades of TLR4, Akt2/3, GSK-3α/β, p38β, p38δ, p38γ, p70S6K1, RSK2, mTOR and AP-1/NK-κB. This data provides a real basis to demonstrate the benefi cial immune modulation activity of this plant (Kouakou et al 2013 (Kamel et al 2007 ). Formaldehyde is the main constituent of air pollution.…”

Influence of carrageenan on cytokine production and cellular activity of mouse peritoneal macrophages and its effect on experimental endotoxemia

“…Monosaccharides such as alditol acetate derivatives were identified by gas chromatography (GC) using an Agilent 6850 gas chromatograph (USA) equipped with an HP‐5MS capillary column (30 m × 0.25 nm) with 5% phenylmethylsiloxane and a flame ionization detector. The analyses were carried out in the temperature range from 175 to 225°C at a rate of 3°C min – . Analysis of the monosaccharide composition of the polysaccharide fractions was performed by the alditol acetate method .…”

“…Natural products are one of the most popular sources of complementary and alternative medicines for preventing and treating inflammatory and immune disorders. It is known that polyionic polysaccharides, due to their ability to interact with the surface receptors of immune cells, can activate various pathways of immunological regulation in organisms …”

“…For instance, mushroom and herb polysaccharides may enhance the cellular and humoral immune responses of chickens to increase their immune tolerance to infectious invasion . At the same time, polysaccharides from the leaves of Clerodendrum splendens are potent natural innate immunomodulators with a vast spectrum of receptor efficacy in vitro and immunosuppressive properties after chronic administration in vivo . Furthermore, β‐glucans and β‐glucan‐containing compounds can act on several immune receptors and activate immune cells such as macrophages, neutrophils, monocytes, natural killer cells and dendritic cells, and therefore modulate innate and adaptive response mechanisms .…”

Effects of fungal- and plant-derived non-starch polysaccharides in macrophages

“…Thus, effects of polysaccharides might be mediated mainly through the toll-like receptors (TLR2 and TRL4), dectin-1 and scavenger receptors, as reported for other botanical polysaccharides (87). The high proportion of arabinose-rich polysaccharides and homogalacturonans and effects on phagocytosis by LPS-pretreated macrophages suggests interaction through TLR4 (88,89). Furthermore, the inhibition of zymosan phagocytosis in macrophages with no pretreatment suggest interaction mainly with dectin-1 and TLR2 (90).…”