Ex vivo nicotine stimulation augments the efficacy of therapeutic bone marrow-derived dendritic cell vaccination

The cancer-immune dialogue in the context of stress

Although there is little direct evidence supporting that stress affects cancer incidence, it does influence the evolution, dissemination and therapeutic outcomes of neoplasia, as shown in human epidemiological analyses and mouse models. The experience of and response to physiological and psychological stressors can trigger neurological and endocrine alterations, which subsequently influence malignant (stem) cells, stromal cells and immune cells in the tumour microenvironment, as well as systemic factors in the tumour macroenvironment. Importantly, stress-induced neuroendocrine changes that can regulate immune responses have been gradually uncovered. Numerous stress-associated immunomodulatory molecules (SAIMs) can reshape natural or therapy-induced antitumour responses by engaging their corresponding receptors on immune cells. Moreover, stress can cause systemic or local metabolic reprogramming and change the composition of the gastrointestinal microbiota which can indirectly modulate antitumour immunity. Here, we explore the complex circuitries that link stress to perturbations in the cancer-immune dialogue and their implications for therapeutic approaches to cancer.

Cholinergic System and Its Therapeutic Importance in Inflammation and Autoimmunity

Neurological and immunological signals constitute an extensive regulatory network in our body that maintains physiology and homeostasis. The cholinergic system plays a significant role in neuroimmune communication, transmitting information regarding the peripheral immune status to the central nervous system (CNS) and vice versa. The cholinergic system includes the neurotransmitter\ molecule, acetylcholine (ACh), cholinergic receptors (AChRs), choline acetyltransferase (ChAT) enzyme, and acetylcholinesterase (AChE) enzyme. These molecules are involved in regulating immune response and playing a crucial role in maintaining homeostasis. Most innate and adaptive immune cells respond to neuronal inputs by releasing or expressing these molecules on their surfaces. Dysregulation of this neuroimmune communication may lead to several inflammatory and autoimmune diseases. Several agonists, antagonists, and inhibitors have been developed to target the cholinergic system to control inflammation in different tissues. This review discusses how various molecules of the neuronal and non-neuronal cholinergic system (NNCS) interact with the immune cells. What are the agonists and antagonists that alter the cholinergic system, and how are these molecules modulate inflammation and immunity. Understanding the various functions of pharmacological molecules could help in designing better strategies to control inflammation and autoimmunity.

K48-Linked Ubiquitination Contributes to Nicotine-Augmented Bone Marrow-Derived Dendritic-Cell-Mediated Adaptive Immunity

K48-linked ubiquitination determining antigen degradation and the endosomal recruitments of p97 and Sec61 plays vital roles in dendritic cell (DC) cross-presentation. Our previous studies revealed that nicotine treatment increases bone marrow-derived dendritic cell (BM-DC) cross-presentation and promotes BM-DC-based cytotoxic T lymphocyte (CTL) priming. But the effect of nicotine on K48-linked ubiquitination and the mechanism of nicotine-increased BM-DC cross-presentation are still uncertain. In this study, we first demonstrated that ex vivo nicotine administration obviously increased K48-linked ubiquitination in BM-DC. Then, we found that K48-linked ubiquitination was essential for nicotine-augmented cross-presentation, BM-DC-based CTL priming, and thereby the superior cytolytic capacity of DC-activated CTL. Importantly, K48-linked ubiquitination was verified to be necessary for nicotine-augmented endosomal recruitments of p97 and Sec61. Importantly, mannose receptor (MR), which is an important antigenic receptor for cross-presentation, was exactly catalyzed with K48-linked ubiquitination by the treatment with nicotine. Thus, these data suggested that K48-linked ubiquitination contributes to the superior adaptive immunity of nicotine-administrated BM-DC. Regulating K48-linked ubiquitination might have therapeutic potential for DC-mediated immune therapy.

Cholinergic modulation of the immune system - A novel therapeutic target for myocardial inflammation

The immune system and the nervous system depend on each other for their fine tuning and working, thus cooperating to maintain physiological homeostasis and prevent infections. The cholinergic system regulates the mobilization, differentiation, secretion, and antigen presentation of adaptive and innate immune cells mainly through α7 nicotinic acetylcholine receptors (α7nAChRs). The neuro-immune interactions are established and maintained by the following mechanisms: colocalization of immune and neuronal cells at defined anatomical sites, expression of the non-neuronal cholinergic system by immune cells, and the acetylcholine receptor-mediated activation of intracellular signaling pathways. Based on these immunological mechanisms, the protective effects of cholinergic system in animal models of diseases were summarized in this paper, such as myocardial infarction/ischemia-reperfusion, viral myocarditis, and endotoxin-induced myocardial damage. In addition to maintaining hemodynamic stability and improving the energy metabolism of the heart, both non-neuronal acetylcholine and neuronal acetylcholine in the heart can alleviate myocardial inflammation and remodeling to exert a significant cardioprotective effect. The new findings on the role of cholinergic agonists and vagus nerve stimulation in immune regulation are updated, so as to develop improved approaches to treat inflammatory heart disease.

Akt+ IKKα/β+ Rab5+ Signalosome Mediate the Endosomal Recruitment of Sec61 and Contribute to Cross-Presentation in Bone Marrow Precursor Cells

Cross-presentation in dendritic cells (DC) requires the endosomal relocations of internalized antigens and the endoplasmic reticulum protein Sec61. Despite the fact that endotoxin-containing pathogen and endotoxin-free antigen have different effects on protein kinase B (Akt) and I-kappa B Kinase α/β (IKKα/β) activation, the exact roles of Akt phosphorylation, IKKα or IKKβ activation in endotoxin-containing pathogen-derived cross-presentation are poorly understood. In this study, endotoxin-free ovalbumin supplemented with endotoxin was used as a model pathogen. We investigated the effects of endotoxin-containing pathogen and endotoxin-free antigen on Akt phosphorylation, IKKα/β activation, and explored the mechanisms that the endotoxin-containing pathogen orchestrating the endosomal recruitment of Sec61 of the cross-presentation in bone marrow precursor cells (BMPC). We demonstrated that endotoxin-containing pathogen and endotoxin-free antigen efficiently induced the phosphorylation of Akt-IKKα/β and Akt-IKKα, respectively. Endotoxin-containing pathogen derived Akt+ IKKα/β+ Rab5+ signalosome, together with augmented the recruitment of Sec61 toward endosome, lead to the increased cross-presentation in BMPC. Importantly, the endosomal recruitment of Sec61 was partly mediated by the formation of Akt+ IKKα/β+ signalosome. Thus, these data suggest that Akt+ IKKα/β+ Rab5+ signalosome contribute to endotoxin-containing pathogen-induced the endosomal recruitment of Sec61 and the superior efficacy of cross-presentation in BMPC.

Ex vivo IL-15 replenishment augments bone marrow precursor cell-mediated adaptive immunity via PI3K-Akt pathway

This study tested the hypothesis that PI3K-Akt activity contributes to the superior immune function of IL-15-administrated bone marrow precursor cells (BMPC). Our previous studies revealed that PI3K-Akt play vital role in dendritic cells (DCs) cross-presentation and DC-based CTL priming. Despite the fact that IL-15 serves multiple functions in its therapeutic potential for the induction and maintenance of T cell response, the exact role of PI3K-Akt in IL-15 increased adaptive immunity is still poorly understood. In this study, we demonstrated that ex vivo IL-15 administration increased BMPC capability of antigen uptake and the expression of costimulatory molecules (such as CD80 and 4-1BB(CD137) ligand [4-1BBL]) and MHC class I molecule via PI3K-Akt pathway. Importantly, PI3K-Akt activity was not only necessary for IL-15 augmented BMPC cross-presentation and CTL priming, but also facilitated IL-15 increased therapeutic potential of the cytolytic capacity and maintenance of BMPC-activated T cells. Thus, these data suggested that PI3K-Akt activity contribute to the superior immune function of IL-15-administrated BMPC and thereby might be therapeutic potential for adaptive immunity.

PYR-41 and Thalidomide Impair Dendritic Cell Cross-Presentation by Inhibiting Myddosome Formation and Attenuating the Endosomal Recruitments of p97 and Sec61 via NF-κB Inactivation

PYR-41 and thalidomide have therapeutic effects on inflammation-associated diseases with side effects such as tumorigenesis. Cross-presentation allows dendritic cells (DC) to present endogenous antigen and induce protective immunity against microbe infection and tumors. But, up to now, the effects of PYR-41 and thalidomide on cross-presentation are still uncertain. In this study, we investigated the effect and mechanism of PYR-41 and thalidomide on DC cross-presentation by observing Myddosome formation, endosomal recruitment of p97 and Sec61, NF-κB activation, and cross-priming ability. We demonstrated that the inhibition of endosomal recruitment of p97 and Sec61, together with attenuated NF-κB activation and Myddosome formation, contributes to PYR-41- and thalidomide-impaired cross-presentation and thereby reverses cross-activation of T cells. These observations suggest that NF-κB signaling and p97 and Sec61 molecules are candidates for dealing with the side effects of PYR-41 and thalidomide.

Increased translocation of antigens to endosomes and TLR4 mediated endosomal recruitment of TAP contribute to nicotine augmented cross-presentation

Cross-presentation by dendritic cells (DCs) requires surface molecules such as lectin, CD40, langerin, heat shock protein, mannose receptor, mediated endocytosis, the endosomal translocation of internalized antigen, and the relocation of transporter associated with antigen processing (TAP). Although the activation of α7 nicotinic acetylcholine receptor (α7 nAchR) up-regulate surface molecule expression, augment endocytosis, and enhance cross-presentation, the molecular mechanism of α7 nAchR activation-increased cross-presentation is still poorly understood. In this study, we investigated the role of mannose receptor in nicotine-increased cross-presentation and the mechanism that endotoxins orchestrating the recruitment of TAP toward endosomes. We demonstrated that nicotine increase the expressiones of mannose receptor and Toll-like receptor 4 (TLR4) via PI3K-Akt-mTOR-p70S6 pathway. Both endosomal translocation of mannose receptor-internalized antigens and TLR4 sig- naling are necessary for nicotine-augmented cross-presentation and cross-priming. Importantly, the recruitment of TAP toward endosomes via TLR4-MyD88-IRAK4 signaling contributes to nicotine-increased cross-presentation and cross-activation of T cells. Thus, these data suggest that increased recruitment of TAP to Ag-containing vesicles contributes to the superior cross-presentation efficacy of α7 nAchR activated DCs.

Cholinergic Modulation of Type 2 Immune Responses

In recent years, the bidirectional relationship between the nervous and immune system has become increasingly clear, and its role in both homeostasis and inflammation has been well documented over the years. Since the introduction of the cholinergic anti-inflammatory pathway, there has been an increased interest in parasympathetic regulation of both innate and adaptive immune responses, including T helper 2 responses. Increasing evidence has been emerging suggesting a role for the parasympathetic nervous system in the pathophysiology of allergic diseases, including allergic rhinitis, asthma, food allergy, and atopic dermatitis. In this review, we will highlight the role of cholinergic modulation by both nicotinic and muscarinic receptors in several key aspects of the allergic inflammatory response, including barrier function, innate and adaptive immune responses, and effector cells responses. A better understanding of these cholinergic processes mediating key aspects of type 2 immune disorders might lead to novel therapeutic approaches to treat allergic diseases.

Nicotine induces TIPE2 upregulation and Stat3 phosphorylation contributes to cholinergic anti-inflammatory effect

Cholinergic anti-inflammatory pathway has therapeutic effect on inflammation-associated diseases. However, the exact mechanism of nicotine-mediated anti-inflammatory effect is still unclear. TIPE2, a new member of tumor necrosis factor-α-induced protein-8 family, is a negative regulator of immune homeostasis. However, the roles of TIPE2 in cholinergic anti-inflammatory effect are still uncertain. Here, we demonstrated that nicotine exerts its anti-inflammatory effect by TIPE2 upregulation and phosphorylated stat3 mediated the inhibition of NF-κB activation, which was supported by the following evidence: firstly, both nicotine and TIPE2 inhibit pro-inflammatory cytokine release via NF-κB inactivation. Secondly, nicotine upregulates TIPE2 expression via α7 nicotinic acetylcholine receptor. Moreover, the enhancement of stat3 phosphorylation and decrease of LPS-induced p65 translocation were achieved by nicotine treatment. Importantly, nicotine treatment augments the interaction of phosphorylated stat3 and p65, indicating that the inhibitory effect of nicotine on NF-κB activation was mediated with protein-protein interactions. Hence, this study revealed that TIPE2 upregulation and stat3 phosphorylation contribute to nicotine-mediated anti-inflammation effect, indicating that TIPE2 and stat3 might be potential molecules for dealing with inflammation-associated diseases.

Tumor necrosis factor α-induced protein 8-like 1 promotes apoptosis by regulating B-cell leukemia/lymphoma-2 family proteins in RAW264.7 cells

Although the newly identified protein tumor necrosis factor α-induced protein 8-like 1 (TNFAIP8L1), also known as TIPE1, has been reported to be able to induce apoptosis in human hepatocellular carcinoma cells, the involvement of TIPE1 in apoptosis remains to be elucidated. The present study investigated the pro-apoptotic effect of TIPE1 in an murine macrophage cell line, RAW264.7. The cell apoptosis rate was detected by flow cytometry. The results revealed that overexpressed TIPE1 could directly enhance the apoptosis and the cisplatin-induced cell death of RAW264.7 cells in vitro. Meanwhile, TIPE1 overexpression could suppress tumor growth in vivo. Furthermore, western blotting revealed that overexpressed TIPE1 could upregulate the expression of B-cell leukemia/lymphoma (Bcl)-2 associated X protein (Bax), Bcl-2 interacting killer (Bik) and p53 upregulated modulator of apoptosis (Puma), and activate the mitogen activated protein kinases (MAPKs) signaling pathway. However, western blotting demonstrated that inhibitors of the MAPKs pathway could not decrease the expression of Bax, Bik or Puma. These results indicated that TIPE1 could promote the apoptosis of RAW264.7 cells by upregulating the pro-apoptotic members of the Bcl-2 family of proteins, and that the MAPKs signaling pathway was not involved in the pro-apoptotic effect of TIPE1.

Ex vivo nicotine stimulation augments the efficacy of human peripheral blood mononuclear cell-derived dendritic cell vaccination via activating Akt-S6 pathway

Our previous studies showed that α7 nicotinic acetylcholine receptor (nAchR) agonist nicotine has stimulatory effects on murine bone marrow-derived semimature DCs, but the effect of nicotine on peripheral blood mononuclear cell- (PBMC-) derived human semimature dendritic cells (hu-imDCs) is still to be clarified. In the present study, hu-imDCs (cultured 4 days) were conferred with  ex vivo lower dose nicotine stimulation and the effect of nicotine on surface molecules expression, the ability of cross-presentation, DCs-mediated PBMC priming, and activated signaling pathways were determined. We could demonstrate that the treatment with nicotine resulted in increased surface molecules expression, enhanced hu-imDCs-mediated PBMC proliferation, upregulated release of IL-12 in the supernatant of cocultured DCs-PBMC, and augmented phosphorylation of Akt and ribosomal protein S6. Nicotine associated with traces of LPS efficiently enhanced endosomal translocation of internalized ovalbumin (OVA) and increased TAP-OVA colocalization. Importantly, the upregulation of nicotine-increased surface molecules upregulation was significantly abrogated by the inhibition of Akt kinase. These findings demonstrate that ex vivo nicotine stimulation augments hu-imDCs surface molecules expression via Akt-S6 pathway, combined with increased Ag-presentation result in augmented efficacy of DCs-mediated PBMC proliferation and Th1 polarization.

Increased antigen presentation but impaired T cells priming after upregulation of interferon-beta induced by lipopolysaccharides is mediated by upregulation of B7H1 and GITRL

Dendritic cells are able to present Ag-derived peptides on MHC class I and II molecules and induce T cells priming. Lipopolysaccharides (LPS), an activator of Toll-like 4 receptor (TLR4) signaling, has been demonstrated to facilitate Ag-presentation, up-regulate surface molecules expression but impair T cells priming. In this study, we investigated the effect of LPS on nicotine-enhanced DCs-dependent T cells priming and the mechanisms of LPS orchestrating the immunosuppressive program. We could demonstrate that the treatment with LPS resulted in increased surface molecules expression, enhanced Ag-presentation, up-regulated release of TGF-beta, TNF-alpha, IL-6, and IFN-beta. Concomititantly, the upregulation of IFN-beta in DCs induces the up-regulation of coinhibitory molecules B7H1 and GITRL, which cause an impaired activation of naïve Ag-specific T cells and the induction of T cell tolerance by enhancing B7H1-PD-1 interactions and promoting GITRL-GITL facilitated Treg generation, respectively. These data provide a mechanistic basis for the immunomodulatory action of IFN-beta which might open new possibilities in the development of therapeutic approaches aimed at the control of excessive immune response and persistent infection.

Nicotine promotes cell proliferation and induces resistance to cisplatin by α7 nicotinic acetylcholine receptor‑mediated activation in Raw264.7 and El4 cells

Although nicotine is a risk factor for carcinogenesis and atherosclerosis, epidemiological data indicate that nicotine has therapeutic benefits in treating Alzheimer's disease. Our previous studies also showed that nicotine-treated dendritic cells have potential antitumor effects. Hence, the precise effects of nicotine on the biological characterizations of cells are controversial. The aim of the present study was to assess the roles of α7 nicotinic acetylcholine receptors (nAChRs), Erk1/2-p38-JNK and PI3K-Akt pathway in nicotine-mediated proliferation and anti-apoptosis effects. The results firstly showed that nicotine treatment clearly augmented cell viability and upregulated PCNA expression in both Raw264.7 and El4 cells. Meanwhile, nicotine afforded protection against cisplatin-induced toxicity through inhibiting caspase-3 activation and upregulating anti-apoptotic protein expression. Further exploration demonstrated that nicotine efficiently abolished cisplatin-promoted mitochondria translocation of Bax and the release of cytochrome c. The pretreatment of α-bungarotoxin and tubocurarine chloride significantly attenuated nicotine-augmented cell viability, abolished caspase-3 activation and α7 nAChR upregulation. Both Erk-JNK-p38 and PI3K-Akt signaling pathways could be activated by nicotine treatment in Raw264.7 and El4 cells. Notably, when Erk-JNK and PI3K-Akt activities were inhibited, nicotine-augmented cell proliferation and anti-apoptotic effects were abolished accordingly. The results presented here indicate that nicotine could achieve α7 nAChR-mediated proliferation and anti-apoptotic effects by activating Erk-JNK and PI3K-Akt pathways respectively, providing potential therapeutic molecules to deal with smoking-associated human diseases.

Nonneuronal Cholinergic System in Breast Tumors and Dendritic Cells: Does It Improve or Worsen the Response to Tumor?

Besides being the main neurotransmitter in the parasympathetic nervous system, acetylcholine (ACh) can act as a signaling molecule in nonneuronal tissues. For this reason, ACh and the enzymes that synthesize and degrade it (choline acetyltransferase and acetylcholinesterase) as well as muscarinic (mAChRs) and nicotinic receptors conform the non-neuronal cholinergic system (nNCS). It has been reported that nNCS regulates basal cellular functions including survival, proliferation, adhesion, and migration. Moreover, nNCS is broadly expressed in tumors and in different components of the immune system. In this review, we summarize the role of nNCS in tumors and in different immune cell types focusing on the expression and function of mAChRs in breast tumors and dendritic cells (DCs) and discussing the role of DCs in breast cancer.

Nicotine up-regulated 4-1BBL expression by activating Mek-PI3K pathway augments the efficacy of bone marrow-derived dendritic cell vaccination

PURPOSE

To explore the role of 4-1BBL in nicotine-treated immature dendritic cells (imDCs) mediated anti-tumor effects.

METHODS

Bone marrow-derived imDCs were stimulated with nicotine and 4-1BBL expression was determinated by flow cytometry, Western blot and RT-PCR respectively. Then, the roles of 4-1BBL in nicotine-augmented DCs-dependent T cell proliferation, CTL priming and anti-tumor effects were investigated by BrdU cell proliferation assay, enzyme-linked immunospot assay and in vivo preventive effect on tumor development, respectively. Finally, using relative kinase inhibitors, the mechanism of 4-1BBL up-regulation by nicotine stimulation and the roles of Mek-PI3K signal pathways in nicotine-augmented DCs-dependent T cell proliferation were explored by Western blot and BrdU cell proliferation assay, respectively.

RESULTS

Firstly, nicotine could up-regulate 4-1BBL expression in both protein and mRNA levels. Secondly, the effects of nicotine-augmented DCs-dependent T-cell proliferation, CTL priming and anti-tumor effects could be significantly abolished by blocking CD80, CD86 and 4-1BBL activity, respectively. Thirdly, the combined blockages of CD80/CD86, CD80/4-1BBL, CD86/4-1BBL or CD80/CD86/4-1BBL signals could decrease 53.2 %, 29.6 %, 27.9 % and 54.5 % nicotine-enhanced T cell proliferation, respectively. Importantly, nicotine-induced 4-1BBL up-regulation could be decreased by the usage of Mek-PI3K pathway kinase inhibitors. The pre-treatment of Mek-p38-PI3K kinase inhibitors could obviously abolish nicotine-augmented DCs-dependent T cell proliferation.

CONCLUSIONS

CD80/CD86 and 4-1BBL are critical for nicotine augmented DCs-mediated anti-tumor effects. 4-1BBL and CD80/CD86 could be considered as potential candidates for preventive and therapeutic tumor vaccination.

Nicotine stimulated bone marrow-derived dendritic cells could augment HBV specific CTL priming by activating PI3K-Akt pathway

Our previous studies have revealed that nicotine-treated immature dendritic cells (imDCs) have anti-tumor effects in murine lymphoma models. The present study is to explore HBV-specific CTL priming and its cytolytic activities of nicotine-treated murine DCs, the mechanism of α7 nicotinic acetylcholine receptor (nAChR) up-regulation by nicotine and the efficiency of nicotine with other cytokines. To address these hypotheses, bone marrow-derived imDCs were stimulated by nicotine and expression of α7 nAChR was firstly determined by flow cytometry and Western blot. Then, DCs-dependent HBV-specific T cell proliferation and IL-12 secretion were secondly determined by BrdU cell proliferation assay and ELISA, respectively. The HBV-specific CTL priming and its activities were further explored by intraperitoneal transfer of nicotine treated imDCs. The mechanism of nicotine up-regulating α7 nAChR was finally explored by Western blot. The results showed that: first, the maximal activation of PI3K and Akt was reached at 30 and 60-120 min respectively after nicotine stimulation. Nicotine up-regulated the expression of α7 nAChR by activating PI3K-Akt pathway in murine DCs; secondly, nicotine stimulation could enhance DCs' ability of HBV-specific T cell proliferation and IL-12 secretion; thirdly, adoptive transfer of nicotine stimulated DCs could induce HBV specific CTL priming in vivo and those CTL had cytolytic activities; fourthly, nicotine had equal efficiencies to 2 ng/ml IFN-γ in DCs-mediated T cell proliferation. All these data presented here indicated that nicotine treated imDCs might be considered as a potential candidate for HBV immunotherapy.

Lipopolysaccharide and dose of nicotine determine the effects of nicotine on murine bone marrow-derived dendritic cells

The reported effects of nicotine on dendritic cells (DCs) are controversial. To investigate the factors which determine the effects of nicotine on DCs, immature dendritic cells (imDCs) induced from murine bone marrow were treated with different doses of nicotine with or without lipopolysaccharides (LPS). The morphology and expression of the co-stimulatory molecules CD80, CD86, CD40 and CD54 were observed and determined by microscopy and flow cytometry, respectively. The results showed that, firstly, nicotine treatment promoted the development of DC precursors into imDCs with a semi-mature phenotype revealed by a higher expression of CD11c and more branched projections. Secondly, lower doses of nicotine (16.5 ng/ml), but not higher (200 μg/ml), up-regulated the expression of the co-stimulatory molecules CD80, CD40 and CD54 on imDCs. Co-administration of LPS and nicotine revealed differential effects on co-stimulatory molecule expression on imDCs. Thirdly and importantly, treatment with lower doses of nicotine (16.5 ng/ml) did not augment expression of the CD80, CD86, CD40 and CD54 molecules in mature DCs. Fourthly and interestingly, high doses of nicotine (more than 165 μg/ml) revealed pro-apoptotic activity but lower doses of nicotine (16.5–0.165 ng/ml) achieved an anti-apoptotic effect on imDCs. All data presented here indicate that the controversial effects of nicotine on DCs may be due to the LPS of the nicotinic environment and the dose of nicotine used.

Cholinergic modulation of dendritic cell function

Dendritic cells (DCs) are highly specialized antigen-presenting cells with a unique ability to activate resting T lymphocytes. Acetylcholine (ACh) is the primary parasympathetic neurotransmitter and also a non-neural paracrine factor produced by different cells. Here, we analyzed the expression of the cholinergic system in DCs. We found that DCs express the muscarinic receptors M(3), M(4) and M(5), as well as the enzymes responsible for the synthesis and degradation of ACh, choline acetyltransferase (ChAT) and acetylcholinesterase (AChE), respectively. Differentiation of DCs in the presence of the cholinergic agonist carbachol, the synthetic analog of ACh, resulted in an increased expression of HLA-DR and CD86 and the stimulation of TNF-α and IL-8 production. All these effects were prevented by atropine, a muscarinic ACh receptor (mAChR) antagonist. Carbachol, was also able to modulate the function of DCs when added after the differentiation is accomplished; it increased the expression of HLA-DR, improved the T cell priming ability of DCs, and stimulated the production of TNF-α but not IL-12 or IL-10. By contrast, carbachol significantly inhibited the stimulation of HLA-DR expression and the enhancement in the T cell priming ability of DCs triggered by LPS. Interestingly, the TNF-α antagonist etanercept completely prevented the increased expression of HLA-DR induced by carbachol, suggesting that it promotes the phenotypic maturation of DCs by stimulating the production of TNF-α. ACh induced similar effects than carbachol; it stimulated the expression of HLA-DR and the production of TNF-α, while inhibiting the stimulation of HLA-DR expression and IL-12 production triggered by LPS. Similarly, neostigmine, an inhibitor of AChE, also stimulated the expression of HLA-DR and the production of TNF-α by DCs while inhibiting the production of TNF-α and IL-12 triggered by LPS. These results support the existence of an autocrine/paracrine loop through which ACh modulates the function of DCs.

Nicotine stimulated dendritic cells could achieve anti-tumor effects in mouse lung and liver cancer

INTRODUCTION

Our previous studies have revealed that nicotine-treated immature dendritic cells (imDCs) have anti-tumor effects in murine lymphoma models. The present study is to explore the preventive and therapeutic anti-tumor effects of nicotine-treated imDCs in murine lung and liver cancer.

MATERIALS AND METHODS

To address this objection, bone marrow-derived imDCs were firstly stimulated by nicotine in vitro and the expressions of CD80, CD86, CD40, CD11b, MHC class I and II were determined by flow cytometry. Then, DCs-dependent tumor-lysate-specific T cell proliferation, IL-12(p40+p70) secretion were determined by BrdU cell proliferation assay and enzyme-linked immunosorbent assay, respectively. The anti-tumor effects of such imDCs were further explored by intraperitoneal transfer against tumor challenge or implantation. By using kinase inhibitors, the mechanism of nicotine upregulating CD80 was finally explored by flow cytometry.

RESULTS

The results showed that: firstly, nicotine could upregulate the expressions of CD80, CD86, CD40,CD11b, MHC class I and II molecules in imDCs. Secondly, nicotine could promote imDCs-dependent T cell priming and IL-12 secretion. Most importantly, systemic transfer of ex vivo nicotine-stimulated imDCs, which enhanced CD80 expression through PI3K activation, could reveal preventive and effectively therapeutic effects on tumor development.

CONCLUSIONS

Ex vivo nicotine stimulation can significantly improve imDCs efficacy for adaptive therapy of cancer. Nicotine-treated imDCs might be considered as a potential candidate for therapeutic tumor immunotherapy for lung and liver cancer.

A polysaccharide extracted from Grifola frondosa enhances the anti-tumor activity of bone marrow-derived dendritic cell-based immunotherapy against murine colon cancer

We previously isolated the novel heteropolysaccharide maitake Z-fraction (MZF) from the maitake mushroom (Grifola frondosa), and demonstrated that MZF significantly inhibited tumor growth by inducing cell-mediated immunity. In this study, we demonstrated that MZF upregulated the expression of CD80, CD86, CD83, and MHC II on bone marrow-derived dendritic cells (DCs) and significantly increased interleukin-12 (IL-12) and tumor necrosis factor-alpha production by DCs in a dose-dependent manner. MZF-treated DCs significantly stimulated both allogeneic and antigen-specific syngenic T cell responses and enhanced antigen-specific interferon-gamma (IFN-gamma) production by syngenic CD4(+) T cells; however, MZF-treated DCs did not affect IL-4 production. Furthermore, the enhancement of IFN-gamma production in CD4(+) T cells, which was induced by MZF-treated DCs, was completely inhibited by the addition of an anti-IL-12 antibody. These results indicate that MZF induced DC maturation and antigen-specific Th1 response by enhancing DC-produced IL-12. We also demonstrated that DCs pulsed with colon-26 tumor lysate in the presence of MZF induced both therapeutic and preventive effects on colon-26 tumor development in BALB/c mice. These results suggest that MZF could be a potential effective adjuvant to enhance immunotherapy using DC-based vaccination.

Neurogenic regulation of dendritic cells in the intestine

Antigen presenting cells like dendritic cells (DC) are responsible for the initiation of adaptive immune responses via the T helper cells they activate. The type of T cell responses DC induce is dependent on the local immunological environment where antigen has been taken up. In the gut, resident DC are phenotypically and functionally shaped by epithelial and stromal cell derived signals, the cytokine microenvironment, and neuronal products. These factors can control the activation state of DC thereby inducing tolerance for food and commensal organisms or immunity against pathogenic microbes. The enteric nervous system (ENS) is increasingly recognized as an important regulatory factor in intestinal immune cell control. Neurotransmitters and neuropeptides like acetylcholine (ACh), norepinephrine (NE) and vasoactive intestinal peptide (VIP) are released by neurons of the ENS and can affect the function of DC and subsequent immune responses. The critical balance between tolerance and protective immunity is disrupted in inflammatory bowel disease, which results in an exaggerated immune response against commensal bacteria. In this review we discuss the effects of ACh, VIP, and NE on DC function. DC express various receptors for these neuron derived products and can alter DC co-stimulatory molecule expression, cytokine release and subsequent T cell activation in an anti-inflammatory fashion. Knowledge about these interactions will help find new drug targets and may facilitate the development of specific therapies for diseases like inflammatory bowel disease (IBD).

Nicotine and inflammatory neurological disorders

Cigarette smoke is a major health risk factor which significantly increases the incidence of diseases including lung cancer and respiratory infections. However, there is increasing evidence that smokers have a lower incidence of some inflammatory and neurodegenerative diseases. Nicotine is the main immunosuppressive constituent of cigarette smoke, which inhibits both the innate and adaptive immune responses. Unlike cigarette smoke, nicotine is not yet considered to be a carcinogen and may, in fact, have therapeutic potential as a neuroprotective and anti-inflammatory agent. This review provides a synopsis summarizing the effects of nicotine on the immune system and its (nicotine) influences on various neurological diseases.

The vagus nerve as a modulator of intestinal inflammation

The cholinergic nervous system attenuates the production of pro-inflammatory cytokines and inhibits inflammatory processes. Hence, in animal models of intestinal inflammation, such as postoperative ileus and dextran sulfate sodium-induced colitis, vagus nerve stimulation ameliorates disease activity. On the other hand, in infectious models of microbial peritonitis, vagus nerve activation seemingly acts counteractive; it impairs bacterial clearance and increases mortality. It is originally indicated that the key mediator of the cholinergic anti-inflammatory pathway, acetylcholine (ACh), inhibits cytokine release directly via the alpha7 nicotinic ACh receptor (nAChR) expressed on macrophages. However, more recent data also point towards the vagus nerve as an indirect modulator of innate inflammatory processes, exerting its anti-inflammatory effects via postganglionic modulation of immune cells in primary immune organs. This review discusses advances in the possible mechanisms by which the vagus nerve can mediate the immune response, and the role of nAChR activation and signalling on macrophages and other immune cells.