Irradiated tumor cells of lipopolysaccharide stimulation elicit an enhanced anti-tumor immunity

A systemically administered detoxified TLR4 agonist displays potent antitumor activity and an acceptable tolerance profile in preclinical models

Bacterial lipopolysaccharides (LPS) are potent innate immunostimulants targeting the Toll-like receptor 4 (TLR4), an attractive and validated target for immunostimulation in cancer therapy. Although LPS possess anti-tumor activity, toxicity issues prevent their systemic administration at effective doses in humans. We first demonstrated that LPS formulated in liposomes preserved a potent antitumor activity per se upon systemic administration in syngeneic models, and significantly enhance the antitumor activity of the anti-CD20 antibody rituximab in mice xenografted with the human RL lymphoma model. Liposomal encapsulation also allowed a 2-fold reduction in the induction of pro-inflammatory cytokines by LPS. Mice receiving an intravenous administration demonstrated a significant increase of neutrophils, monocytes and macrophages at the tumor site as well as an increase of macrophages in spleen. Further, we chemically detoxified LPS to obtain MP-LPS that was associated with a 200-fold decrease in the induction of proinflammatory cytokines. When encapsulated in a clinically approved liposomal formulation, toxicity, notably pyrogenicity (10-fold), was limited while the antitumor activity and immunoadjuvant effect were maintained. This improved tolerance profile of liposomal MP-LPS was associated with the preferential activation of the TLR4-TRIF pathway. Finally, in vitro studies demonstrated that stimulation with encapsulated MP-LPS reversed the polarization of M2 macrophages towards an M1 phenotype, and a phase 1 trial in healthy dogs validated its tolerance upon systemic administration up to very high doses (10µg/kg). Altogether, our results demonstrate the strong therapeutic potential of MPLPS formulated in liposomes as a systemically active anticancer agent, supporting its evaluation in patients with cancer.

Diet-gut microbial interactions influence cancer immunotherapy

The gut microbiome is involved in the absorption and metabolism of host nutrients and modulates the immune response, affecting the efficacy of immunotherapy for cancer. In patients receiving immunotherapy, appropriate modifications of gut microbiota are thought to improve therapeutic response. Of all the factors that influence the gut microbiota, diet is the most influential and modifiable. Healthy dietary patterns as well as some specific dietary components can help the growth of beneficial microbiota in the gut, thereby protecting against cancers and promoting human health. A growing number of researches have confirmed the positive effects of a diet-gut microbiota approach as an adjuvant therapy for cancer, but controversy remains. Here, we summarize the interactions between diet and gut microbes based on previous studies, and discuss the role of gut microbiota-based dietary strategies in tumor immunotherapy, with the potential mechanisms of actions also intensively discussed.

Fusion with human lung cancer cells elongates the life span of human umbilical endothelial cells and enhances the anti-tumor immunity

PURPOSE

Human umbilical endothelial cells (HUVECs) have been proved as an effective whole-cell vaccine inhibiting tumor angiogenesis. However, HUVECs divide a very limited number of passages before entering replicative senescence, which limits its application for clinical situation. Here, we fused HUVECs with human pulmonary adenocarcinoma cell line A549s and investigated the anti-tumor immunity of the hybrids against mice Lewis lung cancer.

METHODS

HUVECs were fused with A549s using polyethylene glycol and were sorted by flow cytometry. The fusion cells (HUVEC-A549s) were confirmed by testing the expression of telomerase and VE-cadherin, the senescence-associated β-galactosidase activity, and tube formation ability. HUVEC-A549s were then irradiated and injected into the C57BL/6 mice of protective, therapeutic, and metastatic models. The mechanism of the anti-tumor immunity was explored by analyzing mice sera, spleen T lymphocytes, tumor microenvironment, and histological changes.

RESULTS

HUVEC-A549s coexpressed tumor and endothelial markers and maintained the vascular function of tube forming at passage 30 without showing signs of senescence. HUVEC-A549s could induce protective and therapeutic anti-tumor activity for LL(2) model and presented stronger activity against metastasis than HUVECs. Both humoral and cellular immunity were participated in the anti-angiogenic activity, as HUVECs-neutralizing IgG and HUVECs-toxic lymphocytes were increased. Angiogenic mediators (VEGF and TGF-β) and tumor microenvironment cells MDSCs and Tregs were also diminished.

CONCLUSIONS

Our findings might provide a novel strategy for HUVECs-related immunotherapy, and this vaccine requires lower culture condition than primary HUVECs while enhancing the anti-tumor immunity.

Antitumor and Adjuvant Activity of λ-carrageenan by Stimulating Immune Response in Cancer Immunotherapy

λ-Carrageenan is a seaweed polysaccharide which has been generally used as proinflammatory agent in the basic research, however, how the immunomodulating activity of λ-carrageenan affects tumor microenvironment remains unknown. In this study, we found that intratumoral injection of λ-carrageenan could inhibit tumor growth in B16-F10 and 4T1 bearing mice and enhance tumor immune response by increasing the number of tumor-infiltrating M1 macrophages, DCs and more activated CD4(+)CD8(+) T lymphocytes in spleen. In addition, λ-carrageenan could enhance the secretion of IL17A in spleen and significantly increase the level of TNF-α in tumor, most of which was secreted by infiltrating macrophages. Moreover, λ-carrageenan exhibited an efficient adjuvant effect in OVA-based preventative and therapeutic vaccine for cancer treatment, which significantly enhanced the production of anti-OVA antibody. The toxicity analysis suggested that λ-carrageenan was with a good safety profile. Thus, λ-carrageenan might be used both as a potent antitumor agent and an efficient adjuvant in cancer immunotherapy.