Omonike Olaleye

Methionine Aminopeptidases from Mycobacterium tuberculosis as Novel Antimycobacterial Targets

Methionine aminopeptidase (MetAP) is a metalloprotease that removes the N-terminal methionine during protein synthesis. To assess the importance of the two MetAPs in Mycobacterium tuberculosis, we overexpressed and purified each of the MetAPs to near homogeneity and showed that both were active as MetAP enzymes in vitro. We screened a library of 175,000 compounds against MtMetAP1c and identified 2,3-dichloro-1,4-naphthoquinone class of compounds as inhibitors of both MtMetAPs. It was found that the MtMetAP inhibitors were active against replicating and aged nongrowing M. tuberculosis. Overexpression of either MtMetAP1a or MtMetAP1c in M. tuberculosis conferred resistance of bacterial cells to the inhibitors. Moreover, knockdown of MtMetAP1a, but not MtMetAP1c, resulted in decreased viability of M. tuberculosis. These results suggest that MtMetAP1a is a promising target for developing antituberculosis agents.

Targeting the role of N-terminal methionine processing enzymes in Mycobacterium tuberculosis

The discovery of anti-tuberculosis agents that target new pathways is crucial for effective short-term TB therapy that will limit the development of resistance. The clinical significance of multidrug-resistant and extensively drug-resistant strains of Mycobacterium tuberculosis, latent TB and Human Immunodeficiency Virus co-infection in tuberculosis patients have made the development of new antimycobacterials more imperative. A better understanding of the major pathways that are involved in the pathogenesis, survival, and dormancy of Mtb will aid in the identification of new drug targets. Here, we review the N-terminal methionine excision (NME) pathway as a potential drug target during host infection with M. tuberculosis. The removal of the N-terminal methionine is a requirement for some proteins prior to post-translational modifications and processing. Therefore, an understanding of the physiological relevance of the two families of enzymes at the center of NME - peptide deformylases and methionine aminopeptidases - has the prospect of adding novel targets and antimycobacterials to the pipeline.

In vitro model of mycobacteria and HIV-1 co-infection for drug discovery

Tuberculosis (TB) has become a global health threat in the wake of the Human Immunodeficiency Virus (HIV) pandemic and is the leading cause of death in people with HIV/AIDS. Treatment of patients with Mycobacterium tuberculosis (Mtb)/HIV co-infection is complicated by drug interactions and toxicity that present huge challenges for clinical intervention. Discovery efforts to identify novel compounds with increased effectiveness and decreased drug-drug interactions against Mtb, HIV-1, or both, would be greatly aided by the use of a co-infection model for screening drug libraries. Currently, inhibitors of Mtb are screened independently in mycobacterial cell cultures or target based biochemical screens and less often in macrophages or peripheral blood leukocytes. Similarly, HIV-1 drugs are screened in vitro independently from anti-mycobacterial compounds. Here, we describe an in vitro model where primary human peripheral blood mononuclear cells or monocyte-derived macrophages are infected with Mycobacterium bovis BCG and HIV-1, and used to evaluate drug toxicity and activity in a co-infection setting. Our results with standard compounds (e.g. Azidothymidine, Rifampicin) demonstrate the utility of this in vitro model to evaluate drug effectiveness relevant to cellular toxicity, HIV-1 replication, and intracellular mycobacterial growth, through the use of ELISA, bacterial enumeration, and multi-variate flow cytometry. This model and associated assays have great value in accelerating the discovery of compounds for use in Mtb/HIV-1 co-infected patients.

Characterization of 2-hydroxy-1-naphthaldehyde isonicotinoyl hydrazone as a novel inhibitor of methionine aminopeptidases from Mycobacterium tuberculosis

Mycobacterium tuberculosis (Mtb) and the Human Immunodeficiency Virus (HIV) pose a major public health threat. The 2015 World Health Organization (WHO) report estimates that one in three HIV deaths is due to Mtb, the causative agent of Tuberculosis (TB). The lethal synergy between these two pathogens leads to a decline in the immune function of infected individuals as well as a rise in morbidity and mortality rates. The deadly interaction between TB and HIV, along with the heightened emergence of drug resistance, drug-drug interactions, reduced drug efficacy and increased drug toxicity, has made the therapeutic management of co-infected individuals a major challenge. Hence, the development of new drug targets and/or new drug leads are imperative for the effective therapeutic management of co-infected patients. Here, we report the characterization of 2-hydroxy-1-naphthaldehyde isonicotinoyl hydrazone (311), a known inhibitor of HIV-1 replication and transcription as a new inhibitor of methionine aminopeptidases (MetAPs) from Mycobacterium tuberculosis: MtMetAP1a and MtMetAP1c. MetAP is a metalloprotease that removes the N-terminal methionine during protein synthesis. The essential role of MetAP in microbes makes it a promising chemotherapeutic target. We demonstrated that 311 is a potent and selective inhibitor of MtMetAP1a and MtMetAP1c. Furthermore, we found that 311 is active against replicating and aged non-growing Mtb at low micromolar concentrations. These results suggest that 311 is a promising lead for the development of novel class of therapeutic agents with dual inhibition of TB and HIV for the treatment of TB-HIV co-infection.

HIV-TB Coinfection among 57 Million Pregnant Women, Obstetric Complications, Alcohol Use, Drug Abuse, and Depression

Objective HIV and tuberculosis represent diseases of major public health importance worldwide. Very little is known about HIV-TB coinfection among pregnant women, especially from industrialized settings. In this study, we examined the association between TB, HIV, and HIV-TB coinfection among pregnant mothers and obstetric complications, alcohol use, drug abuse, and depression. Method We examined inpatient hospital discharges in the United States from January 1, 2002, through December 31, 2014. We employed multivariable survey logistic regression to generate adjusted estimates for the association between infection status and study outcomes. Results We analyzed approximately 57 million records of pregnant women and their delivery information. HIV-TB coinfection was associated with the highest risks for several obstetric complications, alcohol use, and drug abuse. The risk for alcohol abuse was more than twice as high among HIV-monoinfected as compared to TB-monoinfected mothers. That risk gap more than doubled with HIV-TB coinfection. Both HIV-monoinfected and HIV-TB coinfected mothers experienced similarly increased risks for depression. Conclusions Mothers with HIV-TB coinfection experienced relatively heightened risks for obstetric complications, alcohol use, and drug abuse. The findings of this study underscore the importance of augmenting and enhancing social and structural support systems for HIV-TB coinfected pregnant women.

Severe pre-eclampsia among pregnant women with sickle cell disease and HIV

OBJECTIVE The relationship between sickle cell disease (SCD) and severe pre-eclampsia is poorly established. It is also unknown whether the occurrence of HIV infection among women with SCD modifies their risk level for severe pre-eclampsia. We hypothesized that pregnant women with SCD are at an elevated risk for severe pre-eclampsia as a result of heightened endothelial damage; and the combination of SCD-HIV augments the inflammatory processes of endothelial damage leading to amplified risk for severe pre-eclampsia. STUDY DESIGN We analyzed more than 57 million pregnancy-related hospitalizations and births in the US from January 1, 2002 through December 31, 2014. MAIN OUTCOME MEASURES We applied multivariable survey logistic regression to generate odds ratios for the association between SCD, HIV and SCD-HIV status and severe pre-eclampsia with adjustment for potential confounders. RESULTS Of the total 57,326,459 pregnant women, 57,198,505 (99.78%) did not have SCD or HIV, 73,064 (12.7 per 10,000) had HIV only, 54,890 (9.58 per 10,000) had SCD only and 222 (0.39 per 100,000) had both SCD and HIV. Mothers with SCD and HIV-SCD experienced a significant elevation in risk for severe pre-eclampsia of about 60% (OR = 1.61; 95% CI = 1.44, 1.79) and of more than 300% (OR = 4.28; 95% CI = 1.35, 13.62) respectively. CONCLUSION In the largest study on SCD and pre-eclampsia in the world, we established SCD to be strongly associated with severe pre-eclampsia. Another unique finding is the synergistic effect of amplified risk for severe pre-eclampsia among mothers with the combined SCD-HIV status.

A simple, sensitive and reliable LC-MS/MS method for the determination of 7-bromo-5-chloroquinolin-8-ol (CLBQ14), a potent and selective inhibitor of methionine aminopeptidases: Application to pharmacokinetic studies

CLBQ14 is an 8-hydroxyquinoline analogue that inhibits methionine aminopeptidase (MetAP), an enzyme responsible for the post-translational modification of several proteins and polypeptides. MetAP has been validated as druggable target for some infectious diseases, and its inhibitors have been investigated as potential therapeutic agents. In this study, we developed and validated a liquid chromatography tandem-mass spectrometry (LC-MS/MS) method for the quantification of CLBQ14 in solution, and in rat plasma and urine. This method was applied to the pharmacokinetic evaluation of CLBQ14 in adult male Sprague Dawley (SD) rats. Chromatographic separation was achieved using an ultra-high-performance liquid chromatography (UHPLC) system equipped with Waters XTerra MS C18 column (3.5 μm, 125 Å, 2.1 × 50 mm) using 0.1% formic acid in acetonitrile/water gradient system as mobile phase. Chromatographic analysis was performed with a 4000 QTRAP® mass spectrometer using MRM in positive mode for CLBQ14 transition [M + H]+m/z 257.919 → m/z 151.005, and IS (clioquinol) transition [M + H]+m/z 305.783 → m/z 178.917. CLBQ14 was extracted from plasma and urine samples by protein precipitation. The retention times for CLBQ14 and IS were 1.31 and 1.40 min respectively. The standard curves were linear for CLBQ14 concentration ranging from 1 to 1000 ng/mL. The intra-day and inter-day accuracy and precision were found to be within 15% of the nominal concentration. Extraction recoveries were >96.3% and 96.6% from rat plasma and urine respectively, and there was no significant matrix effect from the biological matrices. CLBQ14 is stable in samples subjected to expected storage, preparation, and handling conditions. Pharmacokinetic studies revealed that CLBQ14 has a bi-exponential disposition in SD rats, is extensively distributed with a long plasma half-life and is eliminated primarily by liver metabolism.