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Combating Multidrug Resistant Reservoirs in HIV and Bacterial Pathogens
Multidrug resistance is a major issue in treatment and eradication of diseases. There are many mechanisms by which pathogens develop multi drug resistance. Here we focus on the ability of pathogens to evade drug treatment by establishing multi drug resistant reservoirs. In the case of HIV, the virus is able to evade drug treatment and forms both latent and active replicating reservoirs throughout the body. In the case of many bacterial pathogens, multidrug resistance reservoirs are established within mammalian cells, such as macrophages. Many classes of antibiotics are unable to penetrate mammalian cells, making intracellular bacteria difficult to clear
Previously our research group has developed a Trojan horse strategy to deliver antivirals to HIV cellular reservoirs. Ester based prodrug dimers of abacavir, a reverse transcriptase inhibitor, acted to both inhibit efflux transporters at the BBB and revert to the monomeric therapy in the reducing environments of the cell. Herein we present a new group of sterically hindered carbonate based disulfide linkers that shows improved payload delivery of abacavir and maintain the stability of prodrug molecules towards hydrolysis. We employed these linker molecules to synthesize prodrug dimers of the HIV latency reversal agent prostratin with the hope of targeting latent HIV reservoirs. Payload release studies as well as latency reversal experiments with a latently infected T-helper cell model confirmed that the prostratin carbonate homodimers (ProS2Me2 and ProS2Me4) were able to revert to monomeric prostratin and reverse HIV latency. We next sought to synthesize a prostrain-protease inhibitor heterodimer. While our initial study of a prostratin-lopinavir heterodimer employing this linker strategy (ProLpvS2Me2) did not show significant HIV latency reversal activity, we hope to expand our heterodimer studies to achieve dual therapeutic molecules that can both reverse HIV latency and deliver antivirals to HIV reservoirs.
In order to combat intracellular bacteria our group has focused on development of a novel class of cell penetrating peptides with intrinsic broad spectrum antimicrobial activity that are based on a repeating amino acid triad which forms a cationic amphiphilic polyproline helix (CAPH) scaffold. The first member of this class, P14LRR, exhibited clearance of intracellular bacteria and concentration dependent co-localization within mammalian cells. In efforts to optimize antimicrobial activity we have expanded the CAPHs library by adjusting the chain length between the proline backbone and the guanadinium groups of the cationic amino acids. The first peptide from this expanded library, P14GAP showed much greater cell penetration and antimicrobial activity against a wide range of pathogenic bacteria. However, P14GAP also showed greater toxicity towards mammalian cells, increased hemolysis, and greater membrane binding with mammalian cells as compared to P14LRR. Here we describe the design and synthesis of P14GAP-C1, which contains a methylene between the proline backbone and the guanadinium group. This new analogue decreased the hemolysis activity as compared to P14GAP, although similar membrane binding with mammalian cells was observed. This improvement in hemolysis activity and a slight improvement in cell viability may allow us to use higher concentrations of peptide to treat multidrug resistant bacterial infections.