Dapeng Zhou

Nanoparticle formulated alpha-galactosylceramide activates NKT cells without inducing anergy

Activation of innate immunity is critical for vaccine development and immunotherapy, through triggering antigen specific immune responses. Natural killer T (NKT) cells are a unique type of innate immune cells which exert potent anti-viral and anti-metastasis function, through producing interferon-gamma and activating dendritic cells to present tumor antigens to CD8 T cells. alpha-Galactosylceramide, a synthetic antigen for NKT cells, is an adjuvant for protein antigens which can induce protective immunity against cancer and viral diseases, and has been proven to be safe and immune stimulatory in human cancer and hepatitis patients. Current existing problem for alpha-galactosylceramide is its induction of anergy of NKT cells, due to the non-selective presentation of alpha-galactosylceramide antigen by B cells. We hypothesized that nanoparticle formulated alpha-galactosylceramide may be selectively presented by dendritic cells and macrophages, but not B cells, thus avoiding anergy induction in NKT cells. We have prepared poly-lactic acid based nanoparticles conjugated with alpha-galactosylceramide, examined their stimulation of NKT cells in vitro and in vivo in mice, and showed that nanoparticle formulated alpha-galactosylceramide stimulates NKT cells. In contrast to soluble alpha-galactosylceramide, which caused NKT anergy after single stimulation, nanoparticle formulated alpha-galactosylceramide repeatedly stimulates NKT cells without inducing anergy. Mechanistic studies showed that nanoparticle formulated alpha-galactosylceramide is efficiently presented by mouse CD11c+population containing dendritic cells, and CD11b+population containing macrophages, but very poorly by B220+population containing B cells. Hence, nanoparticle formulated alpha-galactosylceramide is an attractive immunomodulator for immunotherapy and vaccine development. Future studies will be focused on its application as adjuvant for protein and/or peptide antigens.

Alpha-galactosylceramide is an effective mucosal adjuvant for repeated intranasal or oral delivery of HIV peptide antigens.

Mucosal delivery of vaccines against sexually transmitted pathogens is important to elicit strong immune responses at biologically relevant sites. However, inclusion of appropriate adjuvants is essential to overcome the inherent mucosal tolerance. We present evidence in support of the effectiveness of co-administering alpha-galactosylceramide (alpha-GalCer) as an adjuvant with a CTL-inducing HIV envelope peptide, via either oral or intranasal route, to prime antigen-specific immune responses in multiple systemic and mucosal compartments. Contrary to the known potential of repeated parenteral dosing with alpha-GalCer to induce NKT cell anergy that could compromise adoptive immunity development, we have observed that two and three doses delivered by the intranasal or oral route were more efficient in priming broader antigen-specific immune responses. These results demonstrate the effectiveness of alpha-GalCer as adjuvant for repeated intranasal or oral administration of vaccines for protection against mucosally transmitted pathogens.

Survival Advantage in Patients with Metastatic Breast Cancer Receiving Endocrine Therapy plus Sialyl Tn-KLH Vaccine: Post Hoc Analysis of a Large Randomized Trial.

Background: A multicenter, double blinded, randomized phase III trial of the therapeutic cancer vaccine sialy1-Tn (STn) conjugated to keyhole-limpet Hemocyanin (KLH) was completed in an international cohort of 1,028 women with metastatic breast cancer who had nonprogressive disease or no evidence of disease after first-line chemotherapy (ClinicalTrials.gov, (NCT00003638). STn-KLH was safe and relatively well tolerated but did not affect time to progression (TTP) or overall survival (OS) duration. The purpose of this post hoc analysis was to explore whether patients who received concurrent endocrine therapy and STn-KLH had a TTP or OS benefit. Methods: A retrospective, blinded review of the data from the phase III trial of STn-KLH was performed to ensure that strata assignments were appropriate. We then studied the effect of concomitant endocrine therapy and STn-KLH or KLH on TTP and OS in the cohort described above. We also assessed the TTP and OS by antibody responses in patients who received endocrine therapy. Results: The women treated with concomitant endocrine therapy, a pre-stratified subset comprising approximately one-third of the original study population, and STn-KLH had longer TTP and OS than the control group of women who received KLH alone. Moreover, of the women who received endocrine therapy, those who had a median or greater antibody response (titer >1:320 toward ovine sub maxillary mucin) to the STn-KLH vaccine had significantly longer median OS than those who had a below-median antibody response. Conclusion: Adding STn-KLH to endocrine therapy may improve clinical outcomes with few adverse effects for women with metastatic breast cancer.

Targeted Imaging of Tumor-Associated M2 Macrophages Using a Macromolecular Contrast Agent PG-Gd-NIR813

Tumor-associated macrophages (TAMs) are diverse population containing multiple subtypes. M2 macrophages promote tumor growth and metastasis, in part by secreting a wide range of proangiogenic factors and growth factors. Selective depletion of M2 macrophages has been evaluated as a novel approach to anti-cancer therapy. In this study, a dual magneto-optical imaging probe, PG-Gd-NIR813 was synthesized and evaluated for non-invasive assessment of TAMs after intravenous injection. PG-Gd-NIR813 injected in nude rats bearing C6 tumors showed high uptake of the polymeric contrast agent in the tumor at 1 and 48 h after injection both in vivo and ex vivo optical imaging. T(1)-weighted MR imaging results showed accumulation of PG-Gd-NIR813 into the tumor necrotic area, which was confirmed by TUNEL staining of resected tumors. The uptake of PG-Gd-NIR813 within tumor necrosis decreased after animals were treated by the macrophage-depleting agent. Immunohistochemical staining demonstrated that PG-Gd-NIR813 colocalized with CD68 (marker for macrophages) and CD169 (marker for activated macrophages), but not with CD163 (residential macrophages). Using combined near-infrared fluorescence imaging and magnetic resonance imaging (MRI), we demonstrated that the accumulation of PG-Gd-NIR813 in tumors was mediated through M2 TAMs. Therefore, poly(L-glutamic acid) based reagents could be potentially used to image response to antitumor therapies targeted at M2 TAMs. Furthermore, poly(L-glutamic acid) is a promising carrier for candidate immunotherapeutics targeting M2 TAMs.

A Critical Role of Costimulation during Intrathymic Development of Invariant NK T Cells

CD1d-restricted Vα14+ invariant NK T (iNKT) cells are a specialized αβ T cell subset that regulates both innate and adaptive immunity. Although costimulatory molecules are required for the activation of conventional T cells and for the development of Foxp3+ T cells, their role in iNKT cell regulation is unclear. Here we report that mice deficient in CD80/CD86 and/or B7h exhibit severe defects in thymic iNKT cell maturation, associated with largely reduced iNKT cell number in the thymus and the periphery. We show that costimulation is necessary for the optimal expansion of postselected NK1.1− immature iNKT cells in the thymus and for the proper expression of the maturation markers T-bet and CD122. Surprisingly, costimulatory molecules on both hemopoietic and nonhematopoietic cells are required for iNKT cell development. Our results thus demonstrate a previously unknown function of costimulation in the intrathymic development of iNKT cells, distinct from that of conventional T cells and regulatory T cells.

Antitumor Activity Mediated by CpG: The Route of Administration is Critical

Unmethylated CpG oligodeoxynucleotides (CpG) are synthetic toll-like receptor 9 agonists that activate innate immune cells and which have been tested as an immune therapy in a number of cancer clinical trials. Although some antitumor immune responses have been reported, so far the majority of studies have failed to show significant clinical responses to CpG. Here we showed that the route of administration is critical to the antitumor activity of CpG. Although intravenous (i.v.) injection of CpG was capable of inducing the activation and expansion of tumor antigen-specific T cells, most of these activated T cells failed to migrate to tumor sites. By contrast, intratumoral (i.t.) injection of CpG led to extensive tumor infiltration of antigen-specific T cells and subsequent tumor suppression. We further showed that very high levels of inflammatory chemokines [regulated upon activation, normal T-cell expressed, and secreted (RANTES), interferon-inducible protein-10 (IP-10), monocyte chemoattractant protein-1, monocyte chemotactic protein (MCP5), macrophage inflammatory proteins (MIP1&agr;, and MIP1&bgr;)] were induced in the tumor microenvironment after i.t. CpG injection, compared with administration by the i.v. route. It is interesting to note that, in vivo depletion of plasmacytoid dendritic cells greatly reduced the levels of chemokines induced; also, T-cell accumulation and antitumor effect were impaired. We also showed that i.t. but not i.v. CpG injection induced a broad antigen-specific T-cell response against tumor-derived antigens. Collectively, our data provides evidence that the route of CpG administration is a critical factor in mediating antitumor activity. By inducing localized inflammatory signals at tumor sites, i.t. CpG effectively promotes the migration, activation and function of immune cells, ultimately leading to improved tumor control.

Intranasal but not intravenous delivery of the adjuvant α-galactosylceramide permits repeated stimulation of natural killer T cells in the lung.

Efficient induction of antigen‐specific immunity is achieved by delivering multiple doses of vaccine formulated with appropriate adjuvants that can harness the benefits of innate immune mediators. The synthetic glycolipid α‐galactosylceramide (α‐GalCer) is a potent activator of NKT cells, a major innate immune mediator cell type effective in inducing maturation of DCs for efficient presentation of co‐administered antigens. However, systemic administration of α‐GalCer results in NKT cell anergy in which the cells are unresponsive to subsequent doses of α‐GalCer. We show here that α‐GalCer delivered as an adjuvant by the intranasal route, as opposed to the intravenous route, enables repeated activation of NKT cells and DCs, resulting in efficient induction of cellular immune responses to co‐administered antigens. We show evidence that after intranasal delivery,α‐GalCer is selectively presented by DCs for the activation of NKT cells, not B cells. Furthermore, higher levels of PD‐1 expression, a potential marker for functional exhaustion of the NKT cells when α‐GalCer is delivered by the intravenous route, are not observed after intranasal delivery. These results support a mucosal route of delivery for the utility of α‐GalCer as an adjuvant for vaccines, which often requires repeated dosing to achieve durable protective immunity.

Agonistic antibody to CD40 boosts the antitumor activity of adoptively transferred T cells in vivo

CD40, a member of the tumor necrosis factor receptor superfamily, is broadly expressed on antigen-presenting cells and other cells, including fibroblasts and endothelial cells. Binding of CD40 and its natural ligand CD40L (CD154) triggers cytokine secretion, and increased expression of costimulatory molecules is required for T-cell activation and proliferation. However, to our knowledge, the use of agonistic antibodies to CD40 to boost adoptively transferred T cells in vivo has not been investigated. The purpose of this study was to determine whether anti-CD40 monoclonal antibody (mAb) in combination with interleukin (IL)-2 could improve the efficacy of in vitro-activated T cells to enhance antitumor activity. Mice bearing B16 melanoma tumors expressing the gp100 tumor antigen were treated with cultured, activated T cells transgenic for a T-cell receptor specifically recognizing gp100, with or without anti-CD40 mAb. In this model, the combination of anti-CD40 mAb with IL-2 led to expansion of adoptively transferred T cells and induced a more robust antitumor response. Furthermore, the expression of CD40 on bone marrow-derived cells and the presence of CD80/CD86 in the host were required for the expansion of adoptively transferred T cells. The use of neutralizing mAb to IL-12 provided direct evidence that enhanced IL-12 secretion induced by anti-CD40 mAb was crucial for the expansion of adoptively transferred T cells. Collectively, these findings provide a rationale to evaluate the potential application of anti-CD40 mAb in adoptive T-cell therapy for cancer.

High expression of lactotriaosylceramide, a differentiation-associated glycosphingolipid, in the bone marrow of acute myeloid leukemia patients

Glycosphingolipids (GSLs) are information-bearing biomolecules that play critical roles in embryonic development, signal transduction and carcinogenesis. Previous studies indicate that certain GSLs are associated with differentiation in acute myeloid leukemia (AML) cells. In this study, we collected bone marrow samples from healthy donors and AML patients and analyzed the GSL expression profiles comprehensively using electrospray ionization linear ion-trap mass spectrometry. The results showed that AML patients had higher expression of the GSL lactotriaosylceramide (Lc3), GM3 and neolactotetraosylceramide (nLc4) in their bone marrow than did the healthy donors (P < 0.05), especially the M1 subtype of AML. To further explore the molecular mechanisms of Lc3, we examined the expression of the Lc3 synthase β1,3-N-acetylglucosaminyltransferase5 (β3Gn-T5) and found that the bone marrow samples of AML patients had 16-fold higher expression of β3Gn-T5 than those of healthy donors (P < 0.05). Our results suggest that AML-associated GSLs Lc3, GM3 and nLc4 are possibly involved in initiation and differentiation of AML.

Aberrant fucosylation of glycosphingolipids in human hepatocellular carcinoma tissues

Glycosylation promoting or inhibiting tumour cell invasion and metastasis is of crucial importance in current cancer research. Tumour‐associated carbohydrate antigens are predominantly expressed on the tumour cell surface. Glycosphingolipids (GSLs) are members of the family. To perform glycosphingolipidomic assays on neutral GSLs obtained from solid hepatocellular carcinoma (HCC) tissues and paired peritumoural tissues by linear ion trap quadrupole‐electrospray ionization mass spectrometry.