Daniel Sepúlveda-Crespo

Synergistic activity profile of carbosilane dendrimer G2-STE16 in combination with other dendrimers and antiretrovirals as topical anti-HIV-1 microbicide

UNLABELLED Polyanionic carbosilane dendrimers represent opportunities to develop new anti-HIV microbicides. Dendrimers and antiretrovirals (ARVs) acting at different stages of HIV replication have been proposed as compounds to decrease new HIV infections. Thus, we determined the potential use of our G2-STE16 carbosilane dendrimer in combination with other carbosilane dendrimers and ARVs for the use as topical microbicide against HIV-1. We showed that these combinations obtained 100% inhibition and displayed a synergistic profile against different HIV-1 isolates in our model of TZM.bl cells. Our results also showed their potent activity in the presence of an acidic vaginal or seminal fluid environment and did not activate an inflammatory response. This study is the first step toward exploring the use of different anionic carbosilane dendrimers in combination and toward making a safe microbicide. Therefore, our results support further studies on dendrimer/dendrimer or dendrimer/ARV combinations as topical anti-HIV-1 microbicide. FROM THE CLINICAL EDITOR This paper describes the first steps toward the use of anionic carbosilane dendrimers in combination with antivirals to address HIV-1, paving the way to further studies on dendrimer/dendrimer or dendrimer/ARV combinations as topical anti-HIV-1 microbicides.

Polyanionic carbosilane dendrimer-conjugated antiviral drugs as efficient microbicides: Recent trends and developments in HIV treatment/therapy

UNLABELLED Polyanionic carbosilane dendrimers (PCDs) are potential candidates for the development of new microbicides for the prevention of HIV transmission. Tenofovir (TFV), which has dual antiviral activity (anti-HIV/HSV-2), and maraviroc (MRV) are the most studied antiretrovirals as microbicides. Here, we introduce developments in the design of innovative dendrimer-based microbicides. We also review and discuss the combination of various PCDs with TFV and/or MRV for their anti-HIV-1 activity and synergistic combinatory potential. Well-defined combinations blocking HIV-1 infection in early steps of HIV-1 replication provide greater efficacy than monotherapy, as reflected by the decrease in concentration and increase in HIV-1 inhibition. These combinations are characterized by lower doses, which minimize toxic side-effects and the emergence of multi-drug resistant mutants. The above facts suggest that the combination of first- and second-generation PCDs with TFV and/or MRV represents a promising candidate microbicide for preventing HIV-1 sexual transmission and simultaneously suppressing HSV-2. FROM THE CLINICAL EDITOR HIV infection remains a significant and unresolved problem for humankind, despite the development of combination antiretroviral therapy. It has been found that polyanionic carbosilane dendrimers have efficacy in preventing HIV transmission. In this comprehensive review article, the authors discuss the current status and latest development of the use of dendrimers in combination with other antiretroviral drugs as microbicides, which should stimulate others into further research in the fight against HIV.

Triple combination of carbosilane dendrimers, tenofovir and maraviroc as potential microbicide to prevent HIV-1 sexual transmission.

AIM To research the synergistic activity by triple combinations of carbosilane dendrimers with tenofovir and maraviroc as topical microbicide. METHODS Cytotoxicity, anti-HIV-1 activity, vaginal irritation and histological analysis of triple combinations were determined. Analysis of combined effects and the median effective concentration were performed using CalcuSyn software. RESULTS Combinations showed a greater broad-spectrum anti-HIV-1 activity than the single-drug, and preserved this activity in acid environment or seminal fluid. The strongest combinations were G2-STE16/G2-S24P/tenofovir, G2-STE16/G2-S16/maraviroc and G2-STE16/tenofovir/maraviroc at 2:2:1, 10:10:1 10:5:1 ratios, respectively. They demonstrated strong synergistic activity profile due to the weighted average combination indices varied between 0.06 and 0.38. No irritation was detected in female BALB/c mice. CONCLUSION The three-drug combination increases their antiviral potency and act synergistically as potential microbicide.

Prevention vaginally of HIV-1 transmission in humanized BLT mice and mode of antiviral action of polyanionic carbosilane dendrimer G2-S16

UNLABELLED The development of a safe, effective, and low-priced topical microbicide to prevent HIV-1 sexual transmission is urgently needed. The emerging field of nanotechnology plays an important role in addressing this challenge. We demonstrate that topical vaginal administration of 3% G2-S16 prevents HIV-1JR-CSF transmission in humanized (h)-BLT mice in 84% with no presence of HIV-1 RNA and vaginal lesions. Second-generation polyanionic carbosilane dendrimer G2-S16 with silica core and 16 sulfonate end-groups exerts anti-HIV-1 activity at an early stage of viral replication, blocking the gp120/CD4 interaction, acting on the virus, and inhibiting the cell-to-cell HIV-1 transmission, confirming its multifactorial and non-specific ability. This study represents the first demonstration that transmission of HIV-1 can be efficiently blocked by vaginally applied G2-S16 in h-BLT mice. These findings provide a step forward in the development of G2-S16-based vaginal microbicides to prevent vaginal HIV-1 transmission in humans. FROM THE CLINICAL EDITOR HIV infections remain a significant problem worldwide and the major route of transmission is through sexual activity. In this article, the authors developed an antiviral agent containing polyanionic carbosilane dendrimer with silica core and 16 sulfonate end-groups. When applied vaginally, this was shown to exert anti-HIV protection. These positive findings may offer hope in the fight against the spread of HIV epidemic.

Polyanionic carbosilane dendrimers prevent hepatitis C virus infection in cell culture

Hepatitis C virus (HCV) infection is a major biomedical problem worldwide. Although new direct antiviral agents (DAAs) have been developed for the treatment of chronic HCV infection, the potential emergence of resistant virus variants and the difficulties to implement their administration worldwide make the development of novel antiviral agents an urgent need. Moreover, no effective vaccine is available against HCV and transmission of the virus still occurs particularly when prophylactic measures are not taken. We used a cell-based system to screen a battery of polyanionic carbosilane dendrimers (PCDs) to identify compounds with antiviral activity against HCV and show that they inhibit effective virus adsorption of major HCV genotypes. Interestingly, one of the PCDs irreversibly destabilized infectious virions. This compound displays additive effect in combination with a clinically relevant DAA, sofosbuvir. Our results support further characterization of these molecules as nanotools for the control of hepatitis C virus spread.

Mechanistic Studies of Viral Entry: An Overview of Dendrimer‐Based Microbicides As Entry Inhibitors Against Both HIV and HSV‐2 Overlapped Infections

This review provides an overview of the development of different dendrimers, mainly polyanionic, against human immunodeficiency virus (HIV) and genital herpes (HSV‐2) as topical microbicides targeting the viral entry process. Vaginal topical microbicides to prevent sexually transmitted infections such as HIV and HSV‐2 are urgently needed. To inhibit HIV/HSV‐2 entry processes, new preventive targets have been established to maximize the current therapies against wild‐type and drug‐resistant viruses. The entry of HIV/HSV‐2 into target cells is a multistep process that triggers a cascade of molecular interactions between viral envelope proteins and cell surface receptors. Polyanionic dendrimers are highly branched nanocompounds with potent activity against HIV/HSV‐2. Inhibitors of each entry step have been identified with regard to generations and surface groups, and possible roles for these agents in anti‐HIV/HSV‐2 therapies have also been discussed. Four potential binding sites for impeding HIV infection (HSPG, DC‐SIGN, GSL, and CD4/gp120 inhibitors) and HSV‐2 infection (HS, gB, gD, and gH/gL inhibitors) exist according to their mechanisms of action and structures. This review clarifies that inhibition of HIV/HSV‐2 entry continues to be a promising target for drug development because nanotechnology can transform the field of HIV/HSV‐2 prevention by improving the efficacy of the currently available antiviral treatments.

Dendrimeric based microbicides against sexual transmitted infections associated to heparan sulfate

Cell surface heparan sulfate (HS) represents a common link that many sexually transmitted infections (STIs) require for infection. The role of HS is associated with several viral STIs, which include those caused by herpes simplex virus (HVS), human immunodeficiency virus (HIV), human papillomavirus (HPV) and hepatitis C virus (HCV). Nowadays, no cure has been found for any of the STIs associated with viral pathogens. In this review, we evaluate dendrimers such as peptide derivatized-dendrimers, carbosilane dendrimers, polysulfated galactose functionalized glycodendrimers and PAMAM dendrimers, among others, as potential candidates for the development of topical microbicides against viral STIs associated with HS. Subsequently, we propose the mechanism of action of these dendrimers and how it might be associated with the relevance of HS in several STIs. HS in just an ancillary factor in the case of HIV-1 infection and it plays a major role in the case of HCV, HSV-2 and HPV viruses. However, the mechanism of action presented by these dendrimers is common in all pathologies, acting at the level of viral entry into the target cell, either directly blocking the viral particles that are meant to bind to the HS or binding to cellular co-receptors.

New anionic carbosilane dendrons functionalized with a DO3A ligand at the focal point for the prevention of HIV-1 infection

ABSTRACT Novel third‐generation polyanionic carbosilane dendrons with sulfonate or carboxylate end‐groups and functionalized with a DO3A ligand at the focal point, and their corresponding copper complexes, have been prepared as antiviral compounds to prevent HIV‐1 infection. The topology enables the compound to have an excellent chelating agent, DO3A, while keeping anionic peripheral groups for a therapeutic action. In this study, the cytotoxicity and anti‐HIV‐1 abilities of carboxylate‐ (5) or sulfonate‐terminated (6) dendrons containing DO3A and their copper complexes (7 or 8) were evaluated. All compounds showed low cytotoxicity and demonstrated potent and broad‐spectrum anti‐HIV‐1 activity in vitro. We also assessed the mode of antiviral action on the inhibition of HIV‐1 through a panel of different in vitro antiviral assays. Our results show that copper‐free dendron 6 protects the epithelial monolayer from short‐term cell disruption. Copper‐free dendrons 5 and 6 exert anti‐HIV‐1 activity at an early stage of the HIV‐1 lifecycle by binding to the envelope glycoproteins of HIV‐1 and by interacting with the CD4 cell receptor and blocking the binding of gp120 to CD4, and consequently HIV‐1 entry. These findings show that copper‐free dendrons 5 and 6 have a high potency against HIV‐1 infection, confirming their non‐specific ability and suggesting that these compounds deserve further study as potential candidate microbicides to prevent HIV‐1 transmission. Graphical abstract Figure. No Caption available. HighlightsNovel bifunctionalized carbosilane dendrons with a DO3A at the focal point and anionic peripheral groups have been prepared.All compounds show a low cytotoxicity and potent and broad‐spectrum anti‐HIV‐1 activity in vitro.Copper‐free dendrons 5 and 6 inhibit the HIV‐1 infection at the entry through the blockade the binding of gp120 to CD4.Copper‐free dendrons 5 and 6 show their non‐specific ability acting on the virus and interacting with the CD4 cell receptor.

Effect of Several HIV Antigens Simultaneously Loaded with G2-NN16 Carbosilane Dendrimer in the Cell Uptake and Functionality of Human Dendritic Cells

Dendrimers are highly branched, star-shaped, and nanosized polymers that have been proposed as new carriers for specific HIV-1 peptides. Dendritic cells (DCs) are the most-potent antigen-presenting cells that play a major role in the development of cell-mediated immunotherapy due to the generation and regulation of adaptive immune responses against HIV-1. This article reports on the associated behavior of two or three HIV-derived peptides simultaneously (p24/gp160 or p24/gp160/NEF) with cationic carbosilane dendrimer G2-NN16. We have found that (i) immature DCs (iDCs) and mature (mDCs) did not capture efficiently HIV peptides regarding the uptake level when cells were treated with G2-NN16-peptide complex alone; (ii) the ability of DCs to migrate was not depending on the peptides presence; and (iii) with the use of molecular dynamic simulation, a mixture of peptides decreased the cell uptake of the other peptides (in particular, NEF hinders the binding of more peptides and is especially obstructing of the binding of gp160 to G2-NN16). The results suggest that G2-NN16 cannot be considered as an alternative carrier for delivering two or more HIV-derived peptides to DCs.

CHAPTER 7:Dendrimers

Dendrimers are polymeric macromolecules constituted of a repetitive sequence of monomers growing step-by-step from a multifunctional core in a radial iterative fashion, not by polymeric reactions. Their synthesis offers the opportunity to generate monodisperse, structure-controlled architectures resulting in utility in specific biomedical applications. Advances in the role of molecular weight and architecture on the behaviour of these dendrimers, together with recent progress in the design of biodegradable chemistries, has permitted the application of these branched polymers as antiviral drugs and in other applications outside medicine.