Nanoparticle-Delivered Multimeric Soluble CD40L DNA Combined with Toll-Like Receptor Agonists as a Treatment for Melanoma

Stimulation of CD40 or Toll-Like Receptors (TLR) has potential for tumor immunotherapy. Combinations of CD40 and TLR stimulation can be synergistic, resulting in even stronger dendritic cell (DC) and CD8+ T cell responses. To evaluate such combinations, established B16F10 melanoma tumors were injected every other day X 5 with plasmid DNA encoding a multimeric, soluble form of CD40L (pSP-D-CD40L) either alone or combined with an agonist for TLR1/2 (Pam₃CSK₄ ), TLR2/6 (FSL-1 and MALP2), TLR3 (polyinosinic-polycytidylic acid, poly(I:C)), TLR4 ( monophosphoryl lipid A, MPL), TLR7 (imiquimod), or TLR9 (Class B CpG phosphorothioate oligodeoxynucleotide, CpG). When used by itself, pSP-D-CD40L slowed tumor growth and prolonged survival, but did not lead to cure. Of the TLR agonists, CpG and poly(I:C) also slowed tumor growth, and the combination of these two TLR agonists was more effective than either agent alone. The triple combination of intratumoral pSP-D-CD40L + CpG + poly(I:C) markedly slowed tumor growth and prolonged survival. This treatment was associated with a reduction in intratumoral CD11c+ dendritic cells and an influx of CD8+ T cells. Since intratumoral injection of plasmid DNA does not lead to efficient transgene expression, pSP-D-CD40L was also tested with cationic polymers that form DNA-containing nanoparticles which lead to enhanced intratumoral gene expression. Intratumoral injections of pSP-D-CD40L-containing nanoparticles formed from polyethylenimine (PEI) or C32 (a novel biodegradable poly(B-amino esters) polymer) in combination with CpG + poly(I:C) had dramatic antitumor effects and frequently cured mice of B16F10 tumors. These data confirm and extend previous reports that CD40 and TLR agonists are synergistic and demonstrate that this combination of immunostimulants can significantly suppress tumor growth in mice. In addition, the enhanced effectiveness of nanoparticle formulations of DNA encoding immunostimulatory molecules such as multimeric, soluble CD40L supports the further study of this technology for tumor immunotherapy.     

Nucleotypic effects without nuclei: genome size and erythrocyte size in mammals.

Previously reported haploid genome sizes (C-values) and erythrocyte sizes (measured as mean dry diameters) were compared for 67 species of mammals representing 31 families and 16 orders. Measurements on erythrocytes of four species of bats were also included in the study. Erythrocyte size was significantly positively correlated with genome size at each of the specific, generic, familial, and ordinal levels, with the relationship becoming much stronger following the exclusion of the order Artiodactyla, a group unique among mammals in terms of red blood cell morphology. Physiologically, these results are relevant in light of the known relationship between C-value and mass-corrected metabolic rate in homeotherms. In evolutionary terms, they provide insights into the constraints on genome expansion among mammals and are therefore of interest in attempts to solve the long-standing C-value enigma (also known as the C-value paradox).     

BET inhibition blocks inflammation-induced cardiac dysfunction and SARS-CoV-2 infection

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Autoinhibition of Endophilin in Solution via Interdomain Interactions

Endophilin is a key protein involved in clathrin-mediated endocytosis. Previous computational and experimental work suggested that the N-terminal helix is embedded into the membrane to induce curvature; however, the role of the SH3 domain remains controversial. To address this issue, we performed computer simulations of the endophilin dimer in solution to understand the interaction between the N-BAR and SH3 domains and its effect on biological function. We predict that the helix binds to the SH3 domain through hydrophobic and salt-bridge interactions. This protects the hydrophobic residues on both domains and keeps the SH3 domain near the end of the N-BAR domain, in agreement with previous experimental results. The complex has a binding strength similar to a few hydrogen bonds (13.0 ± 0.6 kcal/mol), and the SH3 domain stabilizes the structure of the N-terminal helix in solution. Electrostatic calculations show a large region of strongly positive electrostatic potential near the N-terminal that can orient the helix toward the membrane and likely embed the helix into the membrane surface. This predicted mechanism suggests that endophilin can select for both curvature and electrostatic potential when interacting with membranes, highlighting the importance of the SH3 domain in regulating the function of endophilin.     

2,3,7,8-Tetrachlorodibenzo-p-dioxin Slows the Progression of Experimental Cutaneous Leishmaniasis in Susceptible BALB/c and SCID Mice

In a model of experimental cutaneous leishmaniasis, pre-exposure of Leishmania major-resistant mice to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), an aryl hydrocarbon receptor agonist, causes suppression of the protective anti-parasite T helper 1 response while paradoxically also reducing parasite burdens in those animals. In this study, we examined if TCDD exposure could also reduce parasite burdens in L. major-susceptible BALB/c mice. In the highest dose group (160 µg/Kg), TCDD treatment caused a significant reduction of parasite burdens by 10-fold after three weeks while also causing a significant lymphoid atrophy indicating suppression of the non-protective T helper 2 response. A dose-dependent delay of foot lesion progression was also observed such that lesion size in the highest dose group was less than half that of controls after 35 days of infection. Importantly, although TCDD exposure initially reduced disease severity and prolonged the course of disease by as much as three fold in some animals, this effect was transitory and TCDD did not induce resistance to L. major infection. Because TCDD exposure reduced L. major burdens in both resistant and susceptible mice, we hypothesized that TCDD reduces L. major burdens in mice by a mechanism that does not involve adaptive immunity. To test this, severe combined immunodeficient (SCID) mice were used. In mice infected with a moderate number of L. major (10,000), TCDD treatment caused a time- and dose-dependent decrease of parasite burdens by nearly 100-fold after six weeks in the highest dose group (200 µg/Kg). A significant and dose-dependent delay of foot lesion progression was also observed in these animals. These results indicate that TCDD exposure can reduce the severity of leishmanial disease in mice independent of adaptive immunity.