Modulation of macrophage immune responses by Echinacea

Echinacea preparations are widely used herbal medicines for the prevention and treatment of colds and minor infections. There is little evidence for the individual components in Echinacea that contribute to immune regulatory activity. Activity of an ethanolic Echinacea extract and several constituents, including cichoric acid, have been examined using three in vitro measures of macrophage immune function - NF-kappa B, TNF-alpha and nitric oxide (NO). In cultured macrophages, all components except the monoene alkylamide (AA1) decreased lipopolysaccharide (LPS) stimulated NF-kappa B levels. 0.2 mu g/ml cichoric acid and 2.0 mu g/mL Echinacea Premium Liquid (EPL) and EPL alkylamide fraction (EPL AA) were found to significantly decrease TNF-alpha production under LPS stimulated conditions in macrophages. In macrophages, only the alkylamide mixture isolated from the ethanolic Echinacea extract decreased LPS stimulated NO production. In this study, the mixture of alkylamides in the Echinacea ethanolic liquid extract did not respond in the same manner in the assays as the individual alkylamides investigated. While cichoric acid has been shown to affect NF-kappa B, TNF-alpha and NO levels, it is unlikely to be relevant in the Echinacea alterations of the immune response in vivo due to its nonbioavailability - i.e. no demonstrated absorption across the intestinal barrier and no detectable levels in plasma. These results demonstrate that Echinacea is an effective modulator of macrophage immune responses in vitro.

Modulation of the antibody response by Porphyromonas gingivalis and Fusobacterium nucleatum in a mouse model

Successive immunization of mice with Fusobacterium nucleatum and Porphyromonas gingivalis has been shown to modulate the specific serum IgG responses to these organisms. The aim of this study was to investigate these antibody responses further by examining the IgG subclasses induced as well as the opsonizing properties of the specific antibodies. Serum samples from BALB/c mice immunized with F. nucleatum (gp1-F), P. gingivalis (gp2-P), P. gingivalis followed by F. nucleatum (gp3-PF) F. nucleatum followed by P. gingivalis (gp4-FP) or saline alone (gp5-S) were examined for specific IgG1 (Th2) and IgG2a (Th1) antibody levels using an ELISA and the opsonizing properties measured using a neutrophil chemiluminescence assay. While IgG1 and IgG2a subclasses were induced in all immunized groups, there was a tendency towards an IgG1 response in mice immunized with P. gingivalis alone, while immunization with F. nucleatum followed by P. gingivalis induced significantly higher anti-P. gingivalis IgG2a levels than IgG1. The maximum light output due to neutrophil phagocytosis of P. gingivalis occurred at 10 min using nonopsonized bacteria. Chemiluminescence was reduced using serum-opsonized P. gingivalis and, in particular, sera from P. gingivalis-immunized mice (gp2-P), with maximum responses occurring at 40 min. In contrast, phagocytosis of immune serum-opsonized F. nucleatum demonstrated peak light output at 10 min, while that of F. nucleatum opsonized with sera from saline injected mice (gp5-S) and control nonopsonized bacteria showed peak responses at 40 min. The lowest phagocytic response occurred using gp4-FP serum-opsonized F. nucleatum. In conclusion, the results of the present study have demonstrated a systemic Th1/Th2 response in mice immunized with P. gingivalis and/or F. nucleatum with a trend towards a Th2 response in P. gingivalis-immunized mice and a significantly increased anti-P. gingivalis IgG2a (Th1) response in mice immunized with F. nucleatum prior to P. gingivalis. Further, the inhibition of neutrophil phagocytosis of immune serum-opsonized P. gingivalis was modulated by the presence of anti-F. nucleatum antibodies, while anti-P. gingivalis antibodies induced an inhibitory effect on the phagocytic response to F. nucleatum.

Modulation of human V alpha 24(+)V beta 11(+) NKT cells by age, malignancy and conventional anticancer therapies

Immunotherapy strategies aimed at increasing human Valpha24(+)Vbeta11(+) natural killer T (NKT) cell numbers are currently a major focus. To provide further information towards the goal of NKT cell-based immunotherapy, we assessed the effects of age, cancer status and prior anticancer treatment on NKT cell numbers and their expansion capacity following alpha-galactosylceramide (alpha-GalCer) stimulation. The percentage and absolute number of peripheral blood NKT cells was assessed in 40 healthy donors and 109 solid cancer patients ( colorectal ( n = 33), breast ( n = 10), melanoma ( n = 17), lung ( n = 8), renal cell carcinoma ( n = 10), other cancers ( n = 31)). Responsiveness to alpha-GalCer stimulation was also assessed in 28 of the cancer patients and 37 of the healthy donors. Natural killer T cell numbers were significantly reduced in melanoma and breast cancer patients. While NKT numbers decreased with age in healthy donors, NKT cells were decreased in these cancer subgroups despite age and sex adjustments. Prior radiation treatment was shown to contribute to the observed reduction in melanoma patients. Although cancer patient NKT cells were significantly less responsive to alpha-GalCer stimulation, they remained capable of substantial expansion. Natural killer T cells are therefore modulated by age, malignancy and prior anticancer treatment; however, cancer patient NKT cells remain capable of responding to alpha-GalCer-based immenotherapies.

Dissection of peripheral and central endogenous opioid modulation of systemic interleukin-1 beta responses using c-fos expression in the rat brain

In opiate addicts or patients receiving morphine treatment, it has been reported that the immune system is often compromised. The mechanisms responsible for the adverse effects of opioids on responses to infection are not clear but it is possible that central and/or peripheral opioid receptors may be important. We have utilised an experimental immune challenge model in rats, the systemic administration of the human pro-inflammatory cytokine interleukin-1 beta (IL-1 beta) to study the effects of selectively blocking peripheral opioid receptors only (using naloxone methiodide) or after blocking both central and peripheral opioid receptors (using naloxone). Pre-treatment with naloxone methiodide decreased (15%) IL-1 beta-induced Fos-immunoreactivity (Fos-IR) in medial parvocellular paraventricular nucleus (mPVN) corticotropin-releasing hormone (CRH) neurons but increased responses in the ventrolateral medulla (VLM) C1 (65%) and nucleus tractus solitarius (NTS) A2 (110%) catecholamine cell groups and area postrema (136%). However no effect of blocking peripheral opioid receptors was detected in the central nucleus of the amygdala (CeA) or dorsal bed nucleus of the stria terminalis (BNST). We next determined the effect of blocking both central and peripheral opioid receptors with naloxone and, when compared to the naloxone methiodide pre-treated group, a further 60% decrease in Fos-IR mPVN CRH neurons induced by IL-1 beta was detected, which was attributed to block of central opioid receptors. Similar comparisons also detected decreases in Fos-IR neurons induced by IL-1 beta in the VLM A1, VLM C1 and NTS A2 catecholamine cell groups, area postrema, and parabrachial nucleus. In contrast, pre-treatment with naloxone increased Fos-IR neurons in CeA (98%) and dorsal BNST (72%). These results provide novel evidence that endogenous opioids can influence central neural responses to systemic IL-1 beta and also suggest that the differential patterns of activation may arise because of actions at central and/or peripheral opioid receptors that might be important in regulating behavioural, hypothalamic-pituitary-adrenal axis and sympathetic nervous system responses during an immune challenge. (c) 2005 Elsevier Ltd. All rights reserved.