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Chitosan (300 kDa) was degraded by cellulase to chitosans with molecular weights (MWs) of 156, 72, 7.1, and 3.3 kDa and a chitooligosaccharide mixture (COS). Effects of these on NO secretion, cytokine production, and mitogen-activated protein kinase pathways in lipopolysaccharide (LPS)-induced murine RAW 264.7 macrophages were investigated. Larger chitosans (300, 156, 72 kDa) significantly inhibited NO production, whereas smaller chitosans (7.1 & 3.3 kDa, COS) increased NO production. The 156 and 72 kDa chitosans significantly inhibited TNF-α and IL-6 production, whereas the 7.1 kDa chitosan and COS significantly induced their production. The 156 and 72 kDa chitosans inhibited NF-κB activation and iNOS expression by binding to the CR3 (for 156 kDa chitosan), or CR3 and TLR4 receptor (for 72 kDa chitosan). The smaller chitosans (e.g. 7.1 kDa chitosan and COS) activated NF-κB and enhanced iNOS expression by binding to CD14, TLR4, and CR3 receptors to activate JNK signaling proteins.

Cannabidiol (CBD) has been reported to induce apoptosis in immune cells through oxidative stress-related mechanisms. The objective of the present study was to investigate the cellular mechanisms for CBD-induced apoptosis and oxidative stress in human monocytes. Exposure of freshly isolated human monocytes to CBD induced apoptosis in a time- and concentration-dependent manner. Time-course analyses revealed the induction of intracellular reactive oxygen species (ROS) at 1-2 h post CBD (16 μM) exposure. By comparison, the CBD treatment rapidly elicited the depolarization of mitochondrial membrane potential (MMP) within 5 min, and the oxidation of cardiolipin, a major lipid component of the mitochondrial inner membrane, within 15 min. Moreover, CBD induced the release of cytochrome c (Cyt c) from mitochondria. Mechanistic studies revealed that CBD-induced ROS production and apoptosis were not associated with the alteration of mitochondrial superoxide dismutase activity, the electron leakage through mitochondrial respiratory chain, and Fe2+- and Ca2+-mediated mechanisms. In contrast, CBD-induced apoptosis and MMP depolarization were markedly attenuated by the mitochondrial permeability transition pore (MPTP) inhibitor cyclosporin A (CsA), but not the calcineurin inhibitor FK506. Furthermore, CsA prevented cardiolipin oxidation and the MPTP opening induced by CBD. The present study suggests that CBD acts on the mitochondria to elicit ROS generation and apoptosis through MPTP opening and provides critical insights into the cellular mechanisms for CBD-induced oxidative stress in apoptotic monocytes.

Iron oxide nanoparticles (IONPs) have been shown to attenuate T helper (Th)1 and Th2 cell-mediated immunity in ovalbumin (OVA)-sensitized mice. The objective of this study is to investigate the effects of IONPs on the immune responses of Th17 cells, a subset of T cells involved in various inflammatory pathologies. For in vivo study, a murine model of delayed-type hypersensitivity (DTH) was employed. BALB/c mice received a single dose of IONPs (0.2-10 mg iron/kg) via the tail vein 1 h prior to ovalbumin (OVA) sensitization. Their footpads were subcutaneously challenged with OVA to induce DTH reactions. The expression of Th17 cell-related molecules in inflamed footpads were examined by immunohistochemistry. For in vitro study, OVA-primed splenocytes were directly exposed to IONPs (1-100 μg iron/mL), and then re-stimulated with OVA in culture. The expression of Th17 cell-related molecules were measured by reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay. IONP administration attenuated the number of interleukin (IL)-6, IL-17, the transcription factor ROR-γ, and chemokine receptor 6 positive cells in OVA-challenged footpads, whereas the number of transforming growth factor-β, IL-23 and chemokine (C-C motif) ligand 20 positive cells was not altered. Direct exposure of OVA-primed splenocytes to IONPs suppressed the production of IL-6 and IL-17, and the mRNA expression of IL-17 and ROR-γt. These data indicate that exposure to IONPs attenuates Th17 cell responses in vivo and in vitro.

The effect of Lactobacillus reuteri against food allergy was investigated in ovalbumin (OVA)-sensitized BALB/c mice. Oral administration with L. reuteri restored the deteriorated profile of enteric flora, and attenuated allergic diarrhoea, mast cell activation, and serum IgE production in allergic mice. The production of signature T helper (Th)1 and 2 cytokines, namely IFN-γ and IL-4, by splenocytes was suppressed by L. reuteri . Concordantly, the intestinal expression of IFN-γ, IL-4, T-bet and GATA3 was down-regulated. However, L. reuteri augmented the expression of IL-10, TGF-β and Foxp3, and the number of IL-10-secreting CD11c + CD103 + mesenteric lymph node (MLN) cells. Furthermore, direct exposure to heat-killed L. reuteri attenuated OVA-induced cell proliferation and IL-2 secretion by MLN cells. These results demonstrate that L. reuteri possesses anti-allergic activities via modulating enteric flora and promoting tolerogenic immune responses, and suggest L. reuteri as a functional probiotic against food allergy.

Although the development of T helper (Th)1-like regulatory T (Treg) cells under Th1 inflammatory conditions has been reported, the role of Th1-like Treg cells in Th2 allergic responses remains mostly unclear. We previously demonstrated that diosgenin, the major sapogenin contained in the Chinese yam, attenuated food allergy and augmented Th1 and Treg immune responses. In this study, we hypothesized that diosgenin may enhance the induction of Th1-like Treg cells in the gut of mice with food allergy. Ovalbumin (OVA)-sensitized BALB/c mice were gavaged daily with diosgenin and received repeatedly intragastric ovalbumin challenges to induce intestinal allergic responses. The induction of Foxp3+ Treg cells co-expressing Th1-type transcription factors, cytokines and chemokines in the intestine was examined, and the mRNA expression of the chemokines corresponding to Th1-like Treg cells was measured. Diosgenin administration increased the number of Foxp3+ Treg cells co-expressing Th1 markers, including CCR5, CXCR3, IFN-γ and T-bet in the intestine, and enhanced populations of Foxp3+IFN-γ+ and Foxp3+T-bet+ cells that expressed the regulatory cytokine IL-10 in the Peyer's patches. Diosgenin also augmented the intestinal expression of CXCR3, CCL3, and CXCL10. Concordantly, diosgenin increased the number of CXCR3+Foxp3+IL-10 cells in the Peyer's patches. Our data demonstrated the enhanced induction of Th1-like Treg cells in allergic mice treated with diosgenin, providing evidence to suggest a role for Th1-like Treg cells in diosgenin-mediated anti-allergic effects against Th2-type allergy.

The probiotic activity of Lactobacillus murinus against food allergy was investigated. Oral administration with L. murinus restored the deteriorated profile of enteric flora in mice with food allergy and attenuated allergic responses, including allergen-induced diarrhoea, mast cell activation, and serum IgE production. The production of IFN-γ and IL-4 by splenocytes was enhanced and suppressed, respectively, by L. murinus administration. Concordantly, a decreased expression of IL-4 and GATA3 and an increased expression of IFN-γ and T-bet were observed in the duodenum. Moreover, L. murinus enhanced IL-12 production and suppressed OX40 ligand expression by intestinal CD11c+ cells. Direct exposure to heat-killed L. murinus enhanced IFN-γ secretion by mesenteric lymph node cells. These findings demonstrate that L. murinus possesses anti-allergic activities via modulating enteric flora, intestinal CD11c+ cell functionality and the Th1/Th2 immunobalance, and suggest that L. murinus may be employed as a functional probiotic against food allergy.

This study investigated the effect of diosgenin, a yam-derived phytochemical, on the growth of enteric lactic acid bacteria (LAB). The in vivo effect of diosgenin on the density of intestinal flora was examined in a murine model of food allergy. Oral administration with diosgenin markedly restored the diminished density of faecal LAB associated with allergic reactions. The direct effect of diosgenin and several structure-related steroidal compounds on the growth of faecal anaerobes isolated from diosgenin-administered mice was also investigated. The presence of diosgenin significantly enhanced the growth of Lactobacillus murinus and Lactobacillus reuteri, but not enterococci. Structure-activity relationship analysis showed that the prebiotic activity of steroidal sapogenins might require structural elements of the C5-C6 double bond and intact E- and F-rings. Collectively, these results indicate that steroidal sapogenins may be a novel class of prebiotics to LAB.