Immunostimulatory in Vitro and in Vivo Effects of a Water-Soluble Extract from Kale

Aqueous Extract from Leaves of Citrus unshiu Attenuates Lipopolysaccharide-Induced Inflammatory Responses in a Mouse Model of Systemic Inflammation

Inflammation is related to various life-threatening diseases including cancer, neurodegenerative diseases, and metabolic syndrome. Because macrophages are prominent inflammatory cells, regulation of macrophage activation is a key issue to control the onset of inflammation-associated diseases. In this study, we aimed to evaluate the potential anti-inflammatory activity of Citrus unshiu leaf extract (CLE) and to elucidate the mechanism underlying its anti-inflammatory effect. We found the inhibitory activity of CLE on the secretion of proinflammatory cytokines and a chemokine from mouse macrophage-like RAW 264.7 cells and mouse peritoneal macrophages. The inhibitory activity of CLE was attributed to downregulated JNK, p38 MAPK, and NF-κB signaling pathways, leading to suppressed gene expression of inflammation-associated proteins. Oral administration of CLE significantly decreased the serum level of proinflammatory cytokines IL-6 and TNFα and increased that of anti-inflammatory cytokine IL-10 in lipopolysaccharide-induced systemic inflammation mice. In addition, oral administration of CLE decreased secretion and gene expression of several proinflammatory proteins in the liver and spleen of the model mice. Overall results revealed that C. unshiu leaf is effective to attenuate inflammatory responses in vitro and in vivo.

Anti-melanogenic activity of methanolic extract from leaves of Sorbaria sorbifolia var. stellipila Max. on α-MSH-stimulated B16 melanoma 4A5 cells

Background

Melanin is a pigment, which is widely distributed in organisms. In humans, melanin pigments determine eye, hair, and skin color and protect the skin from damage by ultraviolet radiation; however, immoderate distribution of melanin in the skin causes discoloration. In the present study, we screened methanolic extracts from leaves of 47 plant species, most of which are native to East Asia, for the inhibitory activity against melanogenesis.

Methods

B16 melanoma 4A5 cells were used in all assays conducted in this study. Melanin content assay was performed using methanolic extracts from leaves of 47 plant species. Cytotoxicity of the extract from leaves of Sorbaria sorbifolia var. stellipila Max. (SME) was evaluated by WST-8 assay. Tyrosinase activity was determined using the lysate of α-MSH-stimulated B16 melanoma 4A5 cells and L-dopa as a colorimetric substrate. Melanogenic gene expression was determined by quantitative reverse transcription-polymerase chain reaction (qRT-PCR).

Results

SME showed the highest inhibitory activity among tested samples without cytotoxicity. SME exhibited the inhibition potency for the enzymatic activity of tyrosinase. In addition, qRT-PCR result displayed that SME downregulates the expression of melanogenic genes including tyrosinase, TRP-1, TRP-2, and the transcription factor MITF.

Conclusion

Overall results revealed that the extract from leaves of S. sorbifolia var. stellipila Max. has a potential to be used as a skin whitening agent.

Lysozyme from hen egg white ameliorates lipopolysaccharide-induced systemic inflammation in mice

Lysozyme is an anti-bacterial protein that is widely distributed in nature. Our previous studies revealed that lysozyme shows anti-inflammatory effect on hyperinflammatory macrophages in vitro. The effect of lysozyme on lipopolysaccharide-induced inflammation model mice was examined in this study. Oral administration of lysozyme at 2250 mg/kg body weight/day (high-dose group) significantly suppressed interleukin (IL)-6 and tumor necrosis factor-α levels in the serum. IL-6 level in the spleen was significantly suppressed by lysozyme at 450 mg/kg body weight/day (middle-dose group) and high-dose group due to the suppression of gene expression level. The gene expression levels of IL-1β and IL-12 were also decreased by lysozyme in the high-dose group. In addition, lysozyme significantly suppressed IL-6 level in the liver in the high-dose group. Our findings suggest that lysozyme mitigates inflammatory condition in vivo by suppressing inflammatory cytokine levels in serum and organs from LPS-induced inflammation model mice.

Anti-inflammatory effect of lysozyme from hen egg white on mouse peritoneal macrophages

Lysozyme from hen egg has been reported to possess an anti-inflammatory effect. However, little is known about its detailed mechanism. The mechanism of anti-inflammatory effect of lysozyme was examined in this study. When mouse macrophage-like cell line RAW264.7 cells and mouse peritoneal macrophages were activated with lipopolysaccharide (LPS) and then treated with lysozyme, the production of tumor necrosis factor-α and interleukin-6 was significantly suppressed. The effect was induced by suppressing the gene expression levels of both cytokines. Phagocytosis activity of peritoneal macrophages was not altered by the treatment with lysozyme, suggesting that lysozyme shows the anti-inflammatory effect without inhibiting the phagocytotic response of macrophages. In addition, lysozyme inhibited phosphorylation of c-jun N-terminal kinase (JNK) and was taken up by macrophages within 1 h after treatment of the cells with lysozyme. Overall results suggest that lysozyme is taken up intracellularly and suppresses LPS-induced inflammatory responses by inhibiting JNK phosphorylation.

Immunomodulatory Activity of Octenyl Succinic Anhydride Modified Porang (Amorphophallus oncophyllus) Glucomannan on Mouse Macrophage-Like J774.1 Cells and Mouse Primary Peritoneal Macrophages

Porang is a local plant of Indonesia, which has a high content of glucomannan. In this study, porang glucomannan (PG) was esterified with octenyl succinic anhydride (OSA) to enhance emulsion properties to be widely used in food industry. OSA-modified PG (OSA-PG) enhanced the phagocytosis activity of macrophage-like J774.1 cells and mouse peritoneal macrophages. In addition, OSA-PG increased the production of IL-6 and TNF-α by enhancing their gene expression. Immunoblot analysis displayed that OSA-PG tended to activate both nuclear factor-κB and mitogen-activated protein kinase cascades. Treatment of OSA-PG with polymyxin B revealed that cytokine production induced by OSA-PG was not caused by endotoxin contamination. Our findings also indicated that OSA-PG activates macrophages through not only Toll-like receptor (TLR) 4, but another receptor. Overall findings suggested that OSA-PG has a potential as an immunomodulatory food factor by stimulating macrophages.

Immunostimulatory activity of snake fruit peel extract on murine macrophage-like J774.1 cells

Snake fruit (Salacca edulis Reinw.) is a tropical fruit produced in Indonesia. Snake fruit peel is normally discarded as waste. In the present study, it was revealed that snake fruit peel has high bioactivities on stimulation of the immune system. Snake fruit peel extract (SFPE) was prepared by extracting snake fruit peel powder in water for 15 h at 4 °C. SFPE enhanced phagocytotic activity of murine macrophage-like J774.1 cells. Production of cytokine such as tumour necrosis factor (TNF)-α and interleukin (IL)-6 was also stimulated by SFPE. The gene expression levels for these cytokines were elevated. Immunoblot analysis revealed that SFPE enhanced not only nuclear factor (NF)-κB but also mitogen-activated protein kinases signalling cascades such as JNK and p38 in macrophage. Overall findings suggested that SFPE has a potential beneficial effect to promote our body health through the stimulation of macrophage.

Phenylhydroquinone induces loss of thymocytes through cell cycle arrest and apoptosis elevation in p53-dependent pathway

ortho-Phenylphenol has been employed in post-harvest treatment of citrus fruits. Although o-phenylphenol has been reported to cause carcinomas in the urinary tract in rats, toxicity to the immune organs is still unknown. Herein, we report that administration of o-phenylphenol induces thymic atrophy and loss of thymocytes in female BALB/c mice. The influence seems to result from inhibition of the thymocyte development, because increased and decreased populations of the CD4⁻ CD8⁻ double-negative and CD4⁺ CD8⁺ double-positive thymocytes were observed in the o-phenylphenol-administered mice, respectively. ortho-Phenylphenol is metabolized to phenylhydroquinone by cytochrome P450 monooxygenases. Phenylhydroquinone made cell cycle of thymocytes to be arrested through reduced expression of the genes associated with G₂/M phase and through phosphorylation of p53 at Ser15. Phosphorylation of p53 at Ser15 was upregulated by activation of not only ATR but also Erk1/2 and p38, leading to increase of apoptosis. Gene expression of cytochrome P450 1A1 (CYP1A1) was promoted in thymocytes from the o-phenylphenol-administered mice. Overall, our results suggest that o-phenylphenol induces CYP1A1 expression and is metabolized into phenylhydroquinone by the expressed CYP1A1 in thymocytes. The produced phenylhydroquinone in turn induces inhibition of thymocyte development through cell cycle arrest and apoptosis in the p53-dependent pathway.

Immunomodulatory activity of Bengkoang (Pachyrhizus erosus) fiber extract in vitro and in vivo

Bengkoang (Pachyrhizus erosus (L.) Urban) is one of the most popular edible root vegetables in Indonesia. Bengkoang contains fairly large amounts of carbohydrates and crude fiber. The purpose of this research is to evaluate the immunomodulatory effect of the bengkoang fiber extract (BFE) in vitro and in vivo. BFE was prepared by heating the powder of bengkoang fiber suspended in distilled water at 121 °C for 20 min. BFE facilitated IgM production by the human hybridoma cell line HB4C5 cells. In addition, production of IgM, IgG, and IgA by mouse primary splenocytes was facilitated by BFE in a dose-dependent manner. BFE also significantly facilitated production of both interleukin-5 and interleukin-10 by splenocytes. Immunoglobulin production by lymphocytes from the spleen, Peyer's patch, and mesenteric lymph node were significantly activated by oral administration of BFE to mice for 14 days. The serum immunoglobulin levels of IgG, IgM, and IgA were also significantly enhanced. Furthermore, cytokine production by lymphocytes from the spleen, Peyer's patch, and mesenteric lymph node were also facilitated by oral administration of BFE. These results suggest that BFE has positive effects on the immune system in vitro and in vivo.