Parasite Mitogen-Activated Protein Kinases as Drug Discovery Targets to Treat Human Protozoan Pathogens

Protozoan pathogens are a highly diverse group of unicellular organisms, several of which are significant human pathogens. One group of protozoan pathogens includes obligate intracellular parasites such as agents of malaria, leishmaniasis, babesiosis, and toxoplasmosis. The other group includes extracellular pathogens such as agents of giardiasis and amebiasis. An unfortunate unifying theme for most human protozoan pathogens is that highly effective treatments for them are generally lacking. We will review targeting protozoan mitogen-activated protein kinases (MAPKs) as a novel drug discovery approach towards developing better therapies, focusing on Plasmodia, Leishmania, and Toxoplasma, about which the most is known

Tumor-intrinsic PD-L1 signals regulate cell growth, pathogenesis and autophagy in ovarian cancer and melanoma

PD-L1 antibodies produce efficacious clinical responses in diverse human cancers, but the basis for their effects remains unclear, leaving a gap in understanding of how to rationally leverage the therapeutic activity. PD-L1 is widely expressed in tumor cells but its contributions to tumor pathogenicity are incompletely understood. In this study, we evaluated the hypothesis that PD-L1 exerts tumor cell-intrinsic signals that are critical for pathogenesis. Using RNAi methodology, we attenuated PD-L1 in the murine ovarian cell line ID8agg and the melanoma cell line B16 (termed PD-L1lo cells), which express basal PD-L1. We observed that PD-L1lo cells proliferated more weakly than control cells in vitro. As expected, PD-L1lo cells formed tumors in immunocompetent mice relatively more slowly, but unexpectedly, they also formed tumors more slowly in immunodeficient NSG mice. A comparative microarray analysis identified a number of genes involved in autophagy and mTOR signaling that were affected by PD-L1 expression. In support of a functional role, PD-L1 attenuation augmented autophagy and blunted the ability of autophagy inhibitors to limit proliferation in vitro and in vivo in NSG mice. PD-L1 attenuation also elevated mTORC1 activity and augmented the anti-proliferative effects of the mTORC1 inhibitor rapamycin. PD-L1 cells were also relatively deficient in metastasis to the lung and we found that anti-PD-L1 administration could block tumor cell growth and metastasis in NSG mice. This therapeutic effect was observed with B16 cells but not ID8agg cells, illustrating tumor- or tissue-specific effects in the therapeutic setting. Overall, our findings extend understanding of PD-L1 functions, illustrate non-immune effects of anti-PD-L1 immunotherapy and suggest broader uses for PD-L1 as a biomarker for assessing cancer therapeutic responses

Phenotypic Characterization of Escherichia Coli Strains Taken from Human Intestinal and Urinary Tracts

Escherichia coli (E. coli) is a gram negative bacterium commonly found as a commensal in the intestinal tract of humans and other warm blooded animals. The commensal strains of E. coli are non-pathogenic and do not cause an infection in the host. However, some strains of E. coli are pathogenic and can cause several diseases in humans that include neonatal meningitis, intestinal infections and urinary tract infections. Almost 80-85% of the uncomplicated urinary tract infections are caused by uropathogenic E. coli. Our project involved the characterization of 12 strains of E. coli, isolated from humans in health and disease. These strains were characterized since no studies had been conducted on them previously. The E. coli strains were isolated from patients with urinary tract infections and from the intestinal tracts of partners of these patients. Laboratory E. coli strain K12 served as a control. Phenotypic studies were carried out by studying the bacterial physiology in three different conditions. Motility tests were done to identify phenotypes that were similar to and different in behavior with respect to the wild type. Since antimicrobial resistance was a growing problem in urinary tract infections, susceptibility tests were done for these novel strains of E. coli, with the most commonly used antibiotics to treat these infections. Additionally phenotypic profiles were generated for the wild type strain as well as one uropathogenic strain using Phenotype Microarrays manufactured by Biolog., Inc which was a novel technique especially for uropathogenic strains. These plates were unique in helping us identify different phenotypes within a limited time period. The results of our tests showed, some isolates whose phenotypic behavior differed, in terms of growth and motility when compared to the wild type. Antibiotic susceptibility tests enhanced our understanding of determinants of resistance which was crucial for the management of urinary tract infections. Phenotype micro array profiles generated for 2 strains, the wild type E. coli strain and one uropathogenic strain showed a total of 37 differences in carbon, nitrogen, sulfur and phosphorus metabolism in these strains. These differences indicated the likely genome variations between two strains, a fact that was shown for recently sequenced UTI strain CFT073. Therefore phenotypic characterization was useful in establishing genetic variability of the isolates and more specifically of E. coli strains causing urinary tract infections

DEVELOPMENT OF SUSTAINED RELEASE NANOCAPSULES OF CATECHIN RICH EXTRACT FOR ENHANCED BIOAVAILABILITY

Objective: The aim of the study was to develop sustained release nanocapsules of catechin rich extract (CRE) using Eudragit L 100 as a polymer by emulsion solvent evaporation technique with a major focus on enhancing its bioavailability. Methods: CRE and the polymer were subjected for physical compatibility studies using Fourier transform infrared spectroscopy (FT-IR). Nanoparticles were evaluated for percentage yield, drug (catechin) entrapment efficiency and further characterized by scanning electron microscopy (SEM),X-Ray diffraction (XRD) and differential scanning calorimetric (DSC) studies. The in vitro release study was carried out for 12 hours at pH 6.8 and pH 7.4 and the results obtained were fit to kinetic models. Concentration of residual methanol was determined by Gas chromatography (GC). Results: All prepared particles were spherical, non-porous and were in nano-meter range (50-160 nm). The XRD and DSC results suggest that CRE existed in amorphous state in the nanoformulations. The results of in vitro release study for nanocapsules showed the highest drug release of 97.27 % at pH 6.8 (NF1 nanoformulation-1) and low of 67.60 % was observed for (NF3 nanoformulation-2)atpH 7.4. The in vitro release data of nanoformulations showed the highest correlation for Higuchi matrix and Korsmeyer-Peppas, which indicated that drug release occurred via fickian diffusion mechanism. Concentration of methanol, which was used as solvent for the formulation of nanoparticles, was well within the permitted levels, suggesting the safety for oral application. Conclusion: Based on the results, it may be worth to consider further studies on catechinnanoformulations for pilot studies, in vivo studies for clinical application