Immune checkpoint blockade opens a new way to cancer immunotherapy.

Among the main promising systems to triggering therapeutic antitumor immunity is the blockade of immune checkpoints. Immune checkpoint pathways regulate the control and eradication of infections, malignancies, and resistance against a host of autoantigens. Initiation point of the immune response is T cells, which have a critical role in this pathway. As several immune checkpoints are initiated by ligand-receptor interactions, they can be freely blocked by antibodies or modulated by recombinant forms of ligands or receptors. Antibodies against cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) were the first immunotherapeutics that achieved the US Food and Drug Administration approval. Preliminary clinical results with the blockers of additional immune checkpoint proteins, such as programmed cell death protein 1 (PD-1) indicate extensive and different chances to boost antitumor immunity with the objective of conferring permanent clinical effects. This study provides an overview of the immune checkpoint pathways, including CTLA-4, PD-1, lymphocyte activation gene 3, T-cell immunoglobulin and mucin domain 3, B7-H3, and diacylglycerol kinase α and implications of their inhibition in the cancer therapy.

Chitosan nanoparticles as a dual drug/siRNA delivery system for treatment of colorectal cancer.

Nanoparticles are widely used to deliver anticancer drugs and inhibit tumor growth without systemic toxicity. Recently, chitosan has received much attention as a functional biopolymer for encapsulation of small interfering RNA (siRNA). Because of cationic nature, chitosan efficiently encapsulate siRNA and forming nanoparticles. Moreover, biocompatible and biodegradable properties represent chitosan as potential candidate for in vivo siRNA delivery. In the present study we designed carboxymethyl dextran (CMD) chitosan nanoparticles (ChNPs) to encapsulate snail siRNA and anticancer drug doxorubicin (DOX). The effect of ChNPs-drug/siRNA on cell growth and Epithelial mesenchymal transition (EMT) gene expression of HCT-116 cell lines were investigated. Furthermore the efficacy of dual agent nanoparticle to induce apoptosis and inhibit migration of colorectal cancer cells were assessed using Annexin-V and wound healing assays, respectively. The results demonstrated that treatment with dual agent nanoparticles led to significant changes of EMT genes (i.e down regulation of MMP-9 and Vimentin and up regulation of E-cadherin), apoptosis cell death and migration inhibition in HCT-116 cells. In conclusion, ChNPs encapsulating DOX and snail siRNA can be considered as an effective anti-cancer drugs delivery system for the treatment of colorectal cancer.

Recombinant LPG3 Stimulates IFN-Γ and TNF-Α Secretion by Human NK Cells.

BACKGROUND: Natural killer (NK) cells play an important role in early stages of innate immune responses against viral and tumoral attacks. Activation of NK cells by leishmaniasis results in secretion of cytokines such as interferon (IFN)-γ and tumor necrosis factor (TNF)-α, which enhance the phagocytosis and clearance of parasite. Lipophosphoglycan 3 (LPG3), the Leishmania homologous with GRP94 (glucose regulated protein 94), a member of HSP90 family, contributes to LPG assembly as the most abundant macromolecule on the surface of Leishmania promastigotes. METHODS: We purified NK cells from healthy individuals (n=10) using magnetic-activated cell sorting (MACS) technology. Purified NK cells were co-incubated with different concentrations of recombinant LPG3 (rLPG3), and its N-terminal (NT) and C-terminal (CT) fragments. Finally, the production of IFN-γ and TNF-α by NK cells were measured by ELISA. RESULTS: Recombinant LPG3 but not its fragments (CT and NT), could significantly enhance the production of TNF-α by NK cells (P<0.05). Moreover, rLPG3, CT, and NT fragments were markedly stimulated the secretion of IFN-γ by NK cells (P<0.001). CONCLUSION: The Leishmania LPG3 antigen could effectively activate NK cells, in vitro. Leishmania LPG3 participates in the innate immunity against leishmaniasis and thereby improves the effective parasite destruction. However, its efficiency should be tested in vivo.

Design and construction of immune phage antibody library against Tetanus neurotoxin: Production of single chain antibody fragments.

BACKGROUND: Tetanus neurotoxin (TeNT) is composed of a light (LC) and heavy chain (HC) polypeptides, released by anaerobic bacterium Clostridium tetani and can cause fatal life-threatening infectious disease. Toxin HC and LC modules represents receptor binding and zinc metalloprotease activity, respectively. The passive administration of animal-derived antibodies against tetanus toxin has been considered as the mainstay therapy for years. However, this treatment is associated with several adverse effects due to the presence of anti-isotype antibodies. OBJECTIVE: In the present study, we have produced the fully human single chain antibody fragments (HuScFv) from two human antibody phage display libraries. MATERIAL AND METHODS: Twenty-four different HuscFvs were isolated from two anti TeNT immune libraries. Our produced human ScFv (HuScFv) were converted to IgG platform and analyzed regarding their specific reactivity to TeNT. RESULTS: All of the selected scFvs have the same VL but different VH. Three HuscFvs from the first library (TTX15, 51, 75) and two HuscFvs from the second library (TTX16, 20) were chosen to convert to IgG1 using pOptiVEC and pcDNA3.3 systems. Production of IgG1 from transfected DG44 and binding capacity of them to tetanus toxin and toxoid were measured by ELISA. ELISA results showed no detectable production of TTX16 and TTX20 IgG1. Although, TTX51 and TTX75 were converted and produced as IgG1, no reactivity to tetanus toxin and toxoid was observed. However, TTX15 was successfully produced as whole IgG1 platform with reactivity to both tetanus toxin and toxoid. The latter would be an appropriate replacement for conventional polyclonal antibodies if would meet the further characterization including specificity determination, affinity measurement and toxin neutralizing assays. CONCLUSION: Our results demonstrated production of functional IgG1 derived from TTX15 scFv and might be an appropriate replacement for polyclonal Tetabulin but it needs further characterization.