Deok Rim Heo

Enhanced Efficacy of Therapeutic Cancer Vaccines Produced by Co-Treatment with Mycobacterium tuberculosis Heparin-Binding Hemagglutinin, a Novel TLR4 Agonist

Effective activation of dendritic cells (DCs) toward T helper (Th)-1 cell polarization would improve DC-based antitumor immunotherapy, helping promote the development of immunotherapeutic vaccines based on T-cell immunity. To achieve this goal, it is essential to develop effective immune adjuvants that can induce powerful Th1 cell immune responses. The pathogenic organism Mycobacterium tuberculosis includes certain constitutes, such as heparin-binding hemagglutinin (HBHA), that possess a strong immunostimulatory potential. In this study, we report the first clarification of the functions and precise mechanism of HBHA in immune stimulation settings relevant to cancer. HBHA induced DC maturation in a TLR4-dependent manner, elevating expression of the surface molecules CD40, CD80, and CD86, MHC classes I and II and the proinflammatory cytokines IL-6, IL-12, IL-1β, TNF-α, and CCR7, as well as stimulating the migratory capacity of DCs in vitro and in vivo. Mechanistic investigations established that MyD88 and TRIF signaling pathways downstream of TLR4 mediated secretion of HBHA-induced proinflammatory cytokines. HBHA-treated DCs activated naïve T cells, polarized CD4(+) and CD8(+) T cells to secrete IFN-γ, and induced T-cell-mediated cytotoxicity. Notably, systemic administration of DCs that were HBHA-treated and OVA(251-264)-pulsed ex vivo greatly strengthened immune priming in vivo, inducing a dramatic regression of tumor growth associated with long-term survival in a murine E.G7 thymoma model. Together, our findings highlight HBHA as an immune adjuvant that favors Th1 polarization and DC function for potential applications in DC-based antitumor immunotherapy.

Mycobacterium tuberculosislpdC, Rv0462, induces dendritic cell maturation and Th1 polarization.

Mycobacterium tuberculosis, the etiological factor of pulmonary tuberculosis, causes significant morbidity and mortality worldwide. Activation of host immune responses for containment of mycobacterial infections involves participation of innate immune cells, such as dendritic cells (DCs). In this study, we demonstrated that the gene encoding lipoamide dehydrogenase C (lpdC) from M. tuberculosis, Rv0462, induce maturation and activation of DCs involved in the MAPKs signaling pathway. Moreover, Rv0462-treated DCs activated naïve T cells, polarized CD4(+) and CD8(+) T cells to secrete IFN-γ in syngeneic mixed lymphocyte reactions, which would be expected to contribute to Th1 polarization of the immune response. Our results suggest that Rv0462 can contribute to the innate and adaptive immune responses during tuberculosis infection, and thus modulate the clinical course of tuberculosis.

RG-II from Panax ginseng C.A. Meyer suppresses asthmatic reaction

In asthma, T helper 2 (T(H)2)-type cytokines such as interleukin (IL)-4, IL-5, and IL-13 are produced by activated CD4(+) T cells. Dendritic cells played an important role in determining the fate of naive T cells into either T(H)1 or T(H)2 cells. We determined whether RG-II regulates the T(H)1/T(H)2 immune response by using an ovalbumin-induced murine model of asthma. RG-II reduced IL-4 production but increased interferon- gamma production, and inhibited GATA-3 gene expression. RG-II also inhibited asthmatic reactions including an increase in the number of eosinophils in bronchoalveolar lavage fluid, an increase in inflammatory cell infiltration in lung tissues, airway luminal narrowing, and airway hyperresponsiveness. This study provides evidence that RG-II plays a critical role in ameliorating the pathogenic process of asthmatic inflammation in mice. These findings provide new insights into the immunotherapeutic role of RG-II in terms of its effects in a murine model of asthma.

Induction of indoleamine 2,3-dioxygenase expression via heme oxygenase-1-dependant pathway during murine dendritic cell maturation

Heme oxygenase (HO)-1 is expressed in a variety of conditions involved in the regulation of immune responses. In this study, we examined the role of HO-1 in dendritic cell (DC) maturation and expression of indoleamine 2,3-dioxygenase (IDO), a key enzyme that catalyzes the initial, rate-limiting step in tryptophan degradation. IDO deficiency led to diminished phenotypic and functional maturation of DCs in vitro and in vivo. IDO expression and DC maturation was abrogated by the HO inhibitor zinc protoporphrin, but increased by hemin, a potent inducer of HO-1. Moreover, LPS-induced HO-1 expression was mediated by an NF-kappaB-dependent pathway. Our findings provide additional insight into the immunological functions of IDO and HO-1, and suggest possible therapeutic adjuvants for the treatment of DC-related acute and chronic diseases.

An Essential Regulatory Role of Downstream of Kinase-1 in the Ovalbumin-Induced Murine Model of Asthma

The downstream of kinase (DOK)-1 is involved in the protein tyrosine kinase (PTK) pathway in mast cells, but the role of DOK-1 in the pathogenesis of asthma has not been defined. In this study, we have demonstrated a novel regulatory role of DOK-1 in airway inflammation and physiologic responses in a murine model of asthma using lentiviral vector containing DOK-1 cDNA or DOK-1-specific ShRNA. The OVA-induced inflammatory cells, airway hyperresponsiveness, Th2 cytokine expression, and mucus response were significantly reduced in DOK-1 overexpressing mice compared to OVA-challenged control mice. The transgenic introduction of DOK-1 significantly stimulated the activation and expression of STAT-4 and T-bet, while impressively inhibiting the activation and expression of STAT-6 and GATA-3 in airway epithelial cells. On the other hand, DOK-1 knockdown mice enhanced STAT-6 expression and its nuclear translocation compared to OVA-challenged control mice. When viewed in combination, our studies demonstrate DOK-1 regulates allergen-induced Th2 immune responses by selective stimulation and inhibition of STAT-4 and STAT-6 signaling pathways, respectively. These studies provide a novel insight on the regulatory role of DOK-1 in allergen-induced Th2 inflammation and airway responses, which has therapeutic potential for asthma and other allergic diseases.

Venlafaxine inhibits the development and differentiation of dendritic cells through the regulation of P-glycoprotein

Dendritic cells (DC) are professional antigen-presenting cells that have the ability to detect infectious materials; antigens to T lymphocytes, and serve as a bridge between innate and adaptive immunities. DC express the ATP-binding cassette transporters P-glycoprotein (P-gp). P-gp is a 170-kDa transmembrane protein encoded by the mdr-1 gene, a member of highly conserved superfamily of ATP-binding cassette transport proteins. Functionally, P-gp transporters have been described to be required for efficient DC and T cell migration. We report for the first time, at the best of our knowledge, P-gp is also required for DC development and differentiation in mouse bone marrow-derived DC. In this study, we found that an mdr-1 gene and P-gp protein level was increased during DC development and LPS-induced maturation. Moreover, the activity of P-gp was increased LPS-induced DC maturation. Next, we have attempted to determine whether the modulation of P-gp regulates surface molecules expression and cytokine production in DC. Specifically, down-regulation of P-gp by Venlafaxine (VLX) inhibits the differentiation of DC and cytokine production, such as IL-1, IL-10, and IL-12 during DC maturation. Moreover, the P-gp-decreased DC by VLX was displayed impaired induction of T cell polarizations, proliferation, and cytokine production, including IFN-γ, IL-4, and IL-2. Taken together, these findings also broaden current perspective concerning our understanding of the immunopharmacological functions of VLX and the development of therapeutic adjuvants for the treatment of DC-related acute and chronic diseases.

Deoxypodophyllotoxin Induces a Th1 Response and Enhances the Antitumor Efficacy of a Dendritic Cell-based Vaccine

Background Dendritic cell (DC)-based vaccines are currently being evaluated as a novel strategy for tumor vaccination and immunotherapy. However, inducing long-term regression in established tumor-implanted mice is difficult. Here, we show that deoxypohophyllotoxin (DPT) induces maturation and activation of bone marrow-derived DCs via Toll-like receptor (TLR) 4 activation of MAPK and NF-κB. Methods The phenotypic and functional maturation of DPT-treated DCs was assessed by flow cytometric analysis and cytokine production, respectively. DPT-treated DCs was also used for mixed leukocyte reaction to evaluate T cell-priming capacity and for tumor regression against melanoma. Results DPT promoted the activation of CD8+ T cells and the Th1 immune response by inducing IL-12 production in DCs. In a B16F10 melanoma-implanted mouse model, we demonstrated that DPT-treated DCs (DPT-DCs) enhance immune priming and regression of an established tumor in vivo. Furthermore, migration of DPT-DCs to the draining lymph nodes was induced via CCR7 upregulation. Mice that received DPT-DCs displayed enhanced antitumor therapeutic efficacy, which was associated with increased IFN-γ production and induction of cytotoxic T lymphocyte activity. Conclusion These findings strongly suggest that the adjuvant effect of DPT in DC vaccination is associated with the polarization of T effector cells toward a Th1 phenotype and provides a potential therapeutic antitumor immunity.