Mycobacterium tuberculosis Extracellular Vesicle Enrichment through Size Exclusion Chromatography.

The role of extracellular vesicles (EVs) in the context of bacterial infection has emerged as a new avenue for understanding microbial physiology. Specifically, Mycobacterium tuberculosis (Mtb) EVs play a role in the host-pathogen interaction and response to environmental stress. Mtb EVs are also highly antigenic and show potential as vaccine components. The most common method for purifying Mtb EVs is density gradient ultracentrifugation. This process has several limitations, including low throughput, low yield, reliance on expensive equipment, technical challenges, and it can negatively impact the resulting preparation. Size exclusion chromatography (SEC) is a gentler alternative method that combats many of the limitations of ultracentrifugation. This protocol demonstrates that SEC is effective for Mtb EV enrichment and produces high-quality Mtb EV preparations of increased yield in a rapid and scalable manner. Additionally, a comparison to density gradient ultracentrifugation by quantification and qualification procedures demonstrates the benefits of SEC. While the evaluation of EV quantity (nanoparticle tracking analysis), phenotype (transmission electron microscopy), and content (Western blotting) is tailored to Mtb EVs, the workflow provided can be applied to other mycobacteria.

Extracellular Vesicles in Mycobacteria and Tuberculosis.

Tuberculosis (TB) remains a public health issue causing millions of infections every year. Of these, about 15% ultimately result in death. Efforts to control TB include development of new and more effective vaccines, novel and more effective drug treatments, and new diagnostics that test for both latent TB Infection and TB disease. All of these areas of research benefit from a good understanding of the physiology of Mycobacterium tuberculosis (Mtb), the primary causative agent of TB. Mtb secreted protein antigens have been the focus of vaccine and diagnosis research for the past century. Recently, the discovery of extracellular vesicles (EVs) as an important source of secreted antigens in Mtb has gained attention. Similarly, the discovery that host EVs can carry Mtb products during in vitro and in vivo infection has spiked interest because of its potential use in blood-based diagnostics. Despite advances in understanding the content of Mtb and Mtb-infected host extracellular vesicles, our understanding on the biogenesis and role of Mtb and host extracellular vesicles during Mtb infection is still nascent. Here, we explore the current literature on extracellular vesicles regarding Mtb, discuss the host and Mtb extracellular vesicles as distinct entities, and discuss current gaps in the field.

Extraction and Separation of Mycobacterial Proteins.

The extraction and separation of native mycobacterial proteins remain necessary for antigen discovery, elucidation of enzymes to improve rational drug design, identification of physiologic mechanisms, use as reagents for diagnostics, and defining host immune responses. In this chapter, methods for the manipulation of whole mycobacterial cells and culture exudates are described in detail as these methods are the requisite first steps towards native protein isolation. Specifically, several methods for the inactivation of viable Mycobacterium tuberculosis along with qualification assays are provided, as this is key to safe manipulation of cell pastes for downstream processes. Next, the concentration of spent culture filtrate media in order to permit separation of soluble, secreted proteins is described followed by the separation of mycobacteria extracellular vesicles (MEV) from the remaining soluble proteins in spent media. We then describe the generation of whole-cell lysate and facile separation of lysate into subcellular fractions to afford cell wall, cell membrane, and cytosol-enriched proteins. Due to the hydrophobic nature of cell wall and cell membrane proteins, several extraction protocols to resolve protein subsets (such as extraction with urea and SDS) are also provided. Finally, methods for separation of hydrophobic and hydrophilic proteins from both whole-cell lysate and spent culture media are included. While these methods were optimized for the manipulation of Mycobacterium tuberculosis cells, they have been successfully applied to extract and isolate Mycobacterium leprae, Mycobacterium ulcerans, and Mycobacterium avium proteins.

Conversion of stable renal allograft recipients to a bioequivalent cyclosporine formulation.

BACKGROUND: Gengraf capsule, an AB-rated generic cyclosporine for Neoral, has been shown to be bioequivalent in previous studies. The purpose of this pharmacokinetic study performed in stable renal transplant recipients was to evaluate interchangeability of Gengraf and Neoral. METHODS: Using an open-label, three-period design, 50 renal transplant recipients taking stable doses of Neoral completed a multicenter study. Subjects continued their Neoral regimen during period I (days 1-14). Subjects then switched from Neoral on a milligram-for-milligram basis to Gengraf during period II (days 15-28), followed by conversion to the same milligram-for-milligram dosing regimen of Neoral during period III (days 29-35). Twelve-hour pharmacokinetic evaluations (maximum observed blood concentration [C(max) ], concentration before dosing [C(trough) ], time to maximum observed concentration [T(max) ], and area under the blood concentration-vs.-time curve [AUC]) occurred on days 1, 14, 15, 28, and 29. Additional predose samples (C (trough)) were evaluated on days 7, 21, and 35. Laboratory and safety parameters were also evaluated. RESULTS: The pharmacokinetics of Gengraf (C(max), T(max), C(trough), and AUC) were indistinguishable from the Neoral values in stable renal allograft recipients. The bioequivalent capsules were interchangeable with respect to C(max), C(trough), and AUC at steady state and also on conversion from one capsule formulation to the other. The 90% confidence intervals (CI) for the Gengraf versus Neoral comparison at steady state (day 28 vs. day 14) were 0.95 to 1.03 for AUC and 0.92 to 1.04 for C(max). Trough concentrations remained consistent throughout the study, with no need for dosage adjustment in any of the subjects. Gengraf is well tolerated, with an excellent safety profile, comparable to the safety profile of Neoral. CONCLUSIONS The pharmacokinetics of Gengraf are equivalent and indistinguishable from those of Neoral. Gengraf is well tolerated and interchangeable with Neoral in stable renal transplant recipients.

Randomized, open-label preference study of two cyclosporine capsule formulations (usp modified) in stable solid-organ transplant recipients.

BACKGROUND: Prior research has indicated patient dissatisfaction with the odor, size, and taste of cyclosporine capsules, as well as the halitosis and body odor the capsules can cause. OBJECTIVES: The purposes of this investigation were to (1) compare the overall cyclosporine capsule preference (Gengraf vs Neoral) in stable, solid-organ transplant recipients, (2) assess patient preference based on specific capsule attributes, and (3) determine the reliability of the Cyclosporine Capsule SatiSfaCtion Survey (original to this study). METHODS: In this multicenter, randomized, open-label, parallel-group, preference study, patients were recruited from 144 centers in North America with established transplant programs. Solid-organ transplant recipients who had taken stable doses of cyclosporine (Neoral) for >/=2 consecutive months were randomized in a 9:1 ratio to receive another cyclosporine formulation (Gengraf) or to remain on Neoral therapy. Patients completed the Cyclosporine Capsule Satisfaction Survey prior to randomization (baseline survey) and after taking the study drug for 4 weeks (final survey). The survey consisted of multiple attribute items with high face validity in assessing patients' perceptions and preferences with regard to their overall experience, as well as specific attributes of cyclosporine capsules known to affect patient acceptance. RESULTS: The intent-to-treat population included 1906 patients (1211 men, 693 women [sex unknown in 2 patients]; mean [SD] age, 50.2 [12.4] years). A total of 1708 patients were switched to Gengraf; 198 continued on Neoral. Based on their overall experience with both capsule formulations, the majority of patients switched to Gengraf (61.9%) responded that they preferred the Gengraf capsule, compared with 13.7% who preferred the Neoral capsule and 24.4% who indicated no preference (P < 0.001). A similar preference for Gengraf was observed based on capsule odor (66.3%), ease of swallowing (51.5%), taste (57.1%), and impact on breath odor (52.5%) and body odor (48.4%) (P < 0.001 for each test). The results of internal consistency and reproducibility calculations were high for the Cyclosporine Capsule Satisfaction Survey. Internal consistency ranged from alpha = 0.84 to 0.95 for the subscales and was alpha = 0.95 for the overall score. Ranges for reproducibility in the subscales were r = 0.75 to 0.79, with an overall reproducibility of r = 0.85. Guyatt's responsiveness statistics for the subscale and overall scores were moderately high to very high, indicating that the survey is capable of measuring change in response to treatment. CONCLUSIONS: Of the transplant recipients receiving Gengraf in this study, most preferred Gengraf to Neoral based on overall experience, capsule odor, difficulty swallowing, taste, breath odor, and body odor. Among all study patients, fewer patients receiving Gengraf were bothered by capsule odor, difficulty in swallowing, taste, or the impact on breath or body odor compared with patients who continued to receive Neoral. Internal consistency, reproducibility, and responsiveness results show that the Cyclosporine Capsule Satisfaction Survey is a psychometrically valid instrument that is appropriate for use in clinical trials.