4″-Alkyl EGCG Derivatives Induce Cytoprotective Autophagy Response by Inhibiting EGFR in Glioblastoma Cells.

Epidermal growth factor receptor (EGFR)-targeted therapy has been proven vital in the last two decades for the treatment of multiple cancer types, including nonsmall cell lung cancer, glioblastoma, breast cancer and head and neck squamous cell carcinoma. Unfortunately, the majority of approved EGFR inhibitors fall into the drug resistance category because of continuous mutations and acquired resistance. Recently, autophagy has surfaced as one of the emerging underlying mechanisms behind resistance to EGFR-tyrosine kinase inhibitors (TKIs). Previously, we developed a series of 4″-alkyl EGCG (4″-Cn EGCG, n = 6, 8, 10, 12, 14, 16, and 18) derivatives with enhanced anticancer effects and stability. Therefore, the current study hypothesized that 4″-alkyl EGCG might induce cytoprotective autophagy upon EGFR inhibition, and inhibition of autophagy may lead to improved cytotoxicity. In this study, we have observed growth inhibition and caspase-3-dependent apoptosis in 4″-alkyl EGCG derivative-treated glioblastoma cells (U87-MG). We also confirmed that 4″-alkyl EGCG could inhibit EGFR in the cells, as well as mutant L858R/T790M EGFR, through an in vitro kinase assay. Furthermore, we have found that EGFR inhibition with 4″-alkyl EGCG induces cytoprotective autophagic responses, accompanied by the blockage of the AKT/mTOR signaling pathway. In addition, cytotoxicity caused by 4″-C10 EGCG, 4″-C12 EGCG, and 4″-C14 EGCG was significantly increased after the inhibition of autophagy by the pharmacological inhibitor chloroquine. These findings enhance our understanding of the autophagic response toward EGFR inhibitors in glioblastoma cells and suggest a potent combinatorial strategy to increase the therapeutic effectiveness of EGFR-TKIs.

Exploring the antimicrobial potential of isoniazid loaded Cu-based metal-organic frameworks as a novel strategy for effective killing of Mycobacterium tuberculosis.

Tuberculosis (TB) remains one of the most infectious pathogens with the highest human mortality and morbidity. Biofilm formation during Mycobacterium tuberculosis (Mtb) infection is responsible for bacterial growth, communication, and, most essentially, increased resistance/tolerance to antibiotics leading to higher bacterial persistence. Thus, biofilm growth is presently considered a key virulence factor in the case of chronic disease. Metal-Organic Frameworks (MOFs) have recently emerged as a highly efficient system to improve existing antibiotics' therapeutic efficacy and reduce adverse effects. In this regard, we have synthesized Cu-MOF (IITI-3) using a solvothermal approach. IITI-3 was well characterized by various spectroscopic techniques. Herein, IITI-3 was first encapsulated with isoniazid (INH) to form INH@IITI-3 with 10 wt% loading within 1 hour. INH@IITI-3 was well characterized by PXRD, TGA, FTIR, and BET surface area analysis. Furthermore, the drug release kinetics studies of INH@IITI-3 have been performed at pH 5.8 and 7.4 to mimic the small intestine and blood pH, respectively. The results show that drug release follows first-order kinetics. Furthermore, the antimycobacterial activity of INH@IITI-3 demonstrated significant bacterial killing and altered the structural morphology of the bacteria. Moreover, INH@IITI-3 was able to inhibit the mycobacterial biofilm formation upon treatment and showed less cytotoxicity toward the murine RAW264.7 macrophages. Thus, this work significantly opens up new possibilities for the applications of INH@IITI-3 in biofilm infections in Mtb and further contributes to TB therapeutics.

Detection of Peroxisomal Proteins During Mycobacterial Infection.

Peroxisomes are ubiquitous organelles with essential roles in lipid and reactive oxygen species (ROS) metabolism. They are involved in modulating the immune responses during microbial infection, thus having major impact on several bacterial and viral infectious diseases including tuberculosis. Intracellular pathogens such as Mycobacterium tuberculosis (M. tb) employ various strategies to suppress the host oxidative stress mechanisms to avoid killing by the host. Peroxisome-mediated ROS balance is crucial for innate immune responses to M. tb. Therefore, peroxisomes represent promising targets for host-directed therapeutics to tuberculosis. Here, we present protocols used in our laboratory for the culture of M. tb and detection of peroxisomal proteins in M. tb infected macrophages.

Mycobacterium tuberculosis Acetyltransferase Suppresses Oxidative Stress by Inducing Peroxisome Formation in Macrophages.

Mycobacterium tuberculosis (Mtb) inhibits host oxidative stress responses facilitating its survival in macrophages; however, the underlying molecular mechanisms are poorly understood. Here, we identified a Mtb acetyltransferase (Rv3034c) as a novel counter actor of macrophage oxidative stress responses by inducing peroxisome formation. An inducible Rv3034c deletion mutant of Mtb failed to induce peroxisome biogenesis, expression of the peroxisomal ß-oxidation pathway intermediates (ACOX1, ACAA1, MFP2) in macrophages, resulting in reduced intracellular survival compared to the parental strain. This reduced virulence phenotype was rescued by repletion of Rv3034c. Peroxisome induction depended on the interaction between Rv3034c and the macrophage mannose receptor (MR). Interaction between Rv3034c and MR induced expression of the peroxisomal biogenesis proteins PEX5p, PEX13p, PEX14p, PEX11ß, PEX19p, the peroxisomal membrane lipid transporter ABCD3, and catalase. Expression of PEX14p and ABCD3 was also enhanced in lungs from Mtb aerosol-infected mice. This is the first report that peroxisome-mediated control of ROS balance is essential for innate immune responses to Mtb but can be counteracted by the mycobacterial acetyltransferase Rv3034c. Thus, peroxisomes represent interesting targets for host-directed therapeutics to tuberculosis.

Mycobacterium tuberculosis LprE Suppresses TLR2-Dependent Cathelicidin and Autophagy Expression to Enhance Bacterial Survival in Macrophages.

Despite representing a very important class of virulence proteins, the role of lipoproteins in the pathogenesis of Mycobacterium tuberculosis remains elusive. In this study, we investigated the role of putative lipoprotein LprE in the subversion of host immune responses using the M. tuberculosis CDC1551 LprE (LprE Mtb ) mutant (Mtb∆LprE). We show that deletion of LprE Mtb results in reduction of M. tuberculosis virulence in human and mouse macrophages due to upregulation of vitamin D3-responsive cathelicidin expression through the TLR2-dependent p38-MAPK-CYP27B1-VDR signaling pathway. Conversely, episomal expression of LprE Mtb in Mycobacterium smegmatis improved bacterial survival. Infection in siTLR2-treated or tlr2-/- macrophages reduced the survival of LprE Mtb expressing M. tuberculosis and M. smegmatis because of a surge in the expression of cathelicidin. Infection with the LprE Mtb mutant also led to accumulation of autophagy-related proteins (LC3, Atg-5, and Beclin-1) and augmented recruitment of phagosomal (EEA1 and Rab7) and lysosomal (LAMP1) proteins, thereby resulting in the reduction of the bacterial count in macrophages. The inhibition of phago-lysosome fusion by LprE Mtb was found to be due to downregulation of IL-12 and IL-22 cytokines. Altogether, our data indicate that LprE Mtb is an important virulence factor that plays a crucial role in mycobacterial pathogenesis in the context of innate immunity.

In vitro and In vivo toxicity assessment of phytofabricated ZnO nanoparticles showing bacteriostatic effect and larvicidal efficacy against Culex quinquefasciatus.

Murraya koenigii berry extract based zinc oxide nanoparticles (Mk-ZnO NPs) were synthesized by simple co-precipitation method and examined for bacteriostatic and larvicidal efficiency. Synthesized Mk-ZnO NPs were characterized by UV-Vis spectroscopy at 336 nm. X-Ray diffraction (XRD) showed crystalline nature as hexagonal. Fourier transform infrared spectroscopy (FTIR) spectrum exhibited strong peak at 3442.80 cm-1. Field emission scanning electron microscopy (FE-SEM) showed hexagonal shape of the particle. Transmission electron microscopy (TEM) measured 10-15 nm sized Mk-ZnO NPs. EDX peaks confirm 71.99% of zinc and 11.42% of oxide in Mk-ZnO NPs. Minimum inhibitory concentration (MIC) analysis reveals Mk-ZnO NPs inhibit growth of Gram positive (Staphylococcus aureus, Lysinibacillus fusiformis) and Gram negative (Proteus vulgaris, Providencia vermicola) bacteria at 40 and 50 µg mL-1 respectively. Live & dead assay confirms that Mk-ZnO NPs inhibits bacterial growth at 50 µg mL-1. Bacterial biofilm thickness significantly reduced by Mk-ZnO NPs at 50 µg mL-1. In vitro toxicity of Mk-ZnO NPs on RAW 264.7 macrophages determines 90-50% cell viability at concentrations of 10-100 µg mL-1. In vivo toxicity assay results indicate the lethal concentration of Artemia nauplii were LC50-78.73 µg mL-1 and LC90-130.03 µg mL-1. Larvicidal activity of Mk-ZnO NPs towards mosquito larvae of Culex quinquefasciatus were observed at LC50-2.1 µg mL-1 and LC90-12.1 µg mL-1. Finally the study discloses, potential bacteriostatic effect and mosquito larvae controlling capacity of Mk-ZnO NPs.