Spatial mapping of mitochondrial networks and bioenergetics in lung cancer.

Mitochondria are critical to the governance of metabolism and bioenergetics in cancer cells1. The mitochondria form highly organized networks, in which their outer and inner membrane structures define their bioenergetic capacity2,3. However, in vivo studies delineating the relationship between the structural organization of mitochondrial networks and their bioenergetic activity have been limited. Here we present an in vivo structural and functional analysis of mitochondrial networks and bioenergetic phenotypes in non-small cell lung cancer (NSCLC) using an integrated platform consisting of positron emission tomography imaging, respirometry and three-dimensional scanning block-face electron microscopy. The diverse bioenergetic phenotypes and metabolic dependencies we identified in NSCLC tumours align with distinct structural organization of mitochondrial networks present. Further, we discovered that mitochondrial networks are organized into distinct compartments within tumour cells. In tumours with high rates of oxidative phosphorylation (OXPHOSHI) and fatty acid oxidation, we identified peri-droplet mitochondrial networks wherein mitochondria contact and surround lipid droplets. By contrast, we discovered that in tumours with low rates of OXPHOS (OXPHOSLO), high glucose flux regulated perinuclear localization of mitochondria, structural remodelling of cristae and mitochondrial respiratory capacity. Our findings suggest that in NSCLC, mitochondrial networks are compartmentalized into distinct subpopulations that govern the bioenergetic capacity of tumours.

Publisher Correction: In vivo imaging of mitochondrial membrane potential in non-small-cell lung cancer.

An Amendment to this paper has been published and can be accessed via a link at the top of the paper.

In vivo imaging of mitochondrial membrane potential in non-small-cell lung cancer.

Mitochondria are essential regulators of cellular energy and metabolism, and have a crucial role in sustaining the growth and survival of cancer cells. A central function of mitochondria is the synthesis of ATP by oxidative phosphorylation, known as mitochondrial bioenergetics. Mitochondria maintain oxidative phosphorylation by creating a membrane potential gradient that is generated by the electron transport chain to drive the synthesis of ATP1. Mitochondria are essential for tumour initiation and maintaining tumour cell growth in cell culture and xenografts2,3. However, our understanding of oxidative mitochondrial metabolism in cancer is limited because most studies have been performed in vitro in cell culture models. This highlights a need for in vivo studies to better understand how oxidative metabolism supports tumour growth. Here we measure mitochondrial membrane potential in non-small-cell lung cancer in vivo using a voltage-sensitive, positron emission tomography (PET) radiotracer known as 4-[18F]fluorobenzyl-triphenylphosphonium (18F-BnTP)4. By using PET imaging of 18F-BnTP, we profile mitochondrial membrane potential in autochthonous mouse models of lung cancer, and find distinct functional mitochondrial heterogeneity within subtypes of lung tumours. The use of 18F-BnTP PET imaging enabled us to functionally profile mitochondrial membrane potential in live tumours.

Rapid Purification and Formulation of Radiopharmaceuticals via Thin-Layer Chromatography.

Before formulating radiopharmaceuticals for injection, it is necessary to remove various impurities via purification. Conventional synthesis methods involve relatively large quantities of reagents, requiring high-resolution and high-capacity chromatographic methods (e.g., semi-preparative radio-HPLC) to ensure adequate purity of the radiopharmaceutical. Due to the use of organic solvents during purification, additional processing is needed to reformulate the radiopharmaceutical into an injectable buffer. Recent developments in microscale radiosynthesis have made it possible to synthesize radiopharmaceuticals with vastly reduced reagent masses, minimizing impurities. This enables purification with lower-capacity methods, such as analytical HPLC, with a reduction of purification time and volume (that shortens downstream re-formulation). Still, the need for a bulky and expensive HPLC system undermines many of the advantages of microfluidics. This study demonstrates the feasibility of using radio-TLC for the purification of radiopharmaceuticals. This technique combines high-performance (high-resolution, high-speed separation) with the advantages of a compact and low-cost setup. A further advantage is that no downstream re-formulation step is needed. Production and purification of clinical scale batches of [18F]PBR-06 and [18F]Fallypride are demonstrated with high yield, purity, and specific activity. Automating this radio-TLC method could provide an attractive solution for the purification step in microscale radiochemistry systems.

Toll-like receptor responses are suppressed in trauma ICU patients.

BACKGROUND: Inflammation and activation of the innate immune system are often associated with traumatic injury and may involve alterations in toll-like receptor (TLR)-mediated responses. METHODS: A prospective observational study was designed and conducted. Twenty-one severely injured (ISS = 16-41) trauma intensive care unit (ICU) patients and six healthy volunteers that served as controls were enrolled. Anticoagulated whole blood was collected at 2-12 d after ICU admission and incubated in the presence of media alone (baseline), zymosan (TLR2 agonist) or lipopolysaccharide (LPS; TLR4 agonist) for 3 h. Supernatant levels of inflammatory cytokines (IL-1ß, IL-6, IL-10, and TNFα) were determined. RESULTS: TLR2-mediated and TLR4-mediated activation of whole blood cell cultures from both healthy volunteers and subjects-induced elevated cytokine levels over that observed in unstimulated cultures. Baseline values of IL-6 were significantly elevated in subject cultures as compared to healthy volunteers. Healthy volunteer cultures had 2-3-fold greater levels of IL-6 and TNFα than subject cultures when stimulated with zymosan (TLR2 agonist) or LPS (TLR4 agonist). IL-1ß and IL-10 levels did not differ significantly between healthy volunteers and subjects. CONCLUSIONS: The ability of circulating leukocytes from trauma ICU patients to be activated by TLR agonists is markedly suppressed and may play a role in the development of subsequent infectious complications.

The association between the Th-17 immune response and pulmonary complications in a trauma ICU population.

BACKGROUND: The overall immunopathology of the T-helper cell (Th)-17 immune response has been implicated in various inflammatory diseases including pulmonary inflammation; however its potential role in acute respiratory distress syndrome (ARDS) is not defined. This study aimed to evaluate the Th-17 response in bronchoalveolar lavage fluid (BALF) and blood and from trauma patients with pulmonary complications. METHODS: A total of 21 severely injured intensive care unit (ICU) subjects, who were mechanically ventilated and undergoing bronchoscopy, were enrolled. BALF and blood were collected and analyzed for Th-1 (interferon [IFN]γ), Th-2 (interleukin [IL]-4, -10), Th-17 (IL-17A, -17F, -22, 23) and pro-inflammatory (IL-1ß, IL-6, tumor necrosis factor [TNF]α) cytokine levels. RESULTS: Significant levels of the Th-17 cytokines IL-17A, -17F and -21 and IL-6 (which can be classified as a Th-17 cytokine) were observed in the BALF of all subjects. There were no significant differences in Th-17 cytokines between those subjects with ARDS and those without, with the exception of plasma and BALF IL-6, which was markedly greater in ARDS subjects, as compared with controls and non-ARDS subjects. CONCLUSIONS: Trauma patients with pulmonary complications exhibited a significant Th-17 response in the lung and blood, suggesting that this pro-inflammatory milieu may be a contributing factor to such complications.

Detrimental impact of aqueous mobile phases on 18F-labelled radiopharmaceutical analysis via radio-TLC.

The list of new positron-emission tomography (PET) tracers has rapidly grown in the past decade, following discoveries of new biological targets and therapeutic strategies, with several compounds garnering recent regulatory approval for clinical use. During the development of synthesis methods and production of new tracers for imaging, analytical methods for radio-high performance liquid chromatography (radio-HPLC) and radio-thin layer chromatography (radio-TLC) separations need to be developed to assess radiochemical compositions. Radio-TLC is often faster, simpler, and sometimes more accurate than radio-HPLC (as there is no underestimation of [18F]fluoride when analyzing 18F-labeled radiopharmaceuticals). Many protocols have been developed for separating 18F-radiopharmaceuticals on silica TLC plates, typically with [18F]fluoride retained at the origin and the radiopharmaceutical (and impurities) migrating along the plate. Interestingly, many reports describe the use of aqueous conditions to mobilize polar species, but it is known that aqueous conditions can modify silica and alter its chromatographic behavior. In this technical note, we explore the effects that aqueous conditions have on the analysis of 18F-radiopharmaceutical mixtures, revealing that with sufficient water, the radionuclide ([18F]fluoride) can migrate away from the origin and can be split into multiple bands. Furthermore, water can hinder the migration of the radiopharmaceutical. These effects can lead to overlapped bands or reversal of the normally expected order of bands, potentially leading to the misinterpretation of results if care is not taken to validate the TLC method carefully.

A rapid and systematic approach for the optimization of radio thin-layer chromatography resolution.

Radiopharmaceutical analysis is limited by conventional methods. Radio-HPLC may be inaccurate for some compounds (e.g., 18F-radiopharmaceuticals) due to radionuclide sequester. Radio-TLC is simpler, faster, and detects all species but has limited resolution. Imaging-based readout of TLC plates (e.g., using Cerenkov luminescence imaging) can improve readout resolution, but the underlying chromatographic separation efficiency may be insufficient to resolve chemically similar species such as product and precursor-derived impurities. This study applies a systematic mobile phase optimization method, PRISMA, to improve radio-TLC resolution. The PRISMA method optimizes the mobile phase by selecting the correct solvent, optimizing solvent polarity, and optimizing composition. Without prior knowledge of impurities and by simply observing the separation resolution between a radiopharmaceutical and its nearest radioactive or non-radioactive impurities (observed via UV imaging) for different mobile phases, the PRISMA method enabled the development of high-resolution separation conditions for a wide range of 18F-radiopharmaceuticals ( [18F]PBR-06, [18F]FEPPA, [18F]Fallypride, [18F]FPEB, and [18F]FDOPA). Each optimization required a single batch of crude radiopharmaceutical and a few hours. Interestingly, the optimized TLC method provided greater accuracy (compared to other published TLC methods) in determining the product abundance of one radiopharmaceutical studied in more depth ( [18F]Fallypride) and was capable of resolving a comparable number of species as isocratic radio-HPLC. We used the PRISMA-optimized mobile phase for [18F]FPEB in combination with multi-lane radio-TLC techniques to evaluate reaction performance during high-throughput synthesis optimization of [18F]FPEB. The PRISMA methodology, in combination with high-resolution radio-TLC readout, enables a rapid and systematic approach to achieving high-resolution and accurate analysis of radiopharmaceuticals without the need for radio-HPLC.

Microliter-scale reaction arrays for economical high-throughput experimentation in radiochemistry.

The increasing number of positron-emission tomography (PET) tracers being developed to aid drug development and create new diagnostics has led to an increased need for radiosynthesis development and optimization. Current radiosynthesis instruments are designed to produce large-scale clinical batches and are often limited to performing a single synthesis before they must be decontaminated by waiting for radionuclide decay, followed by thorough cleaning or disposal of synthesizer components. Though with some radiosynthesizers it is possible to perform a few sequential radiosyntheses in a day, none allow for parallel radiosyntheses. Throughput of one or a few experiments per day is not well suited for rapid optimization experiments. To combat these limitations, we leverage the advantages of droplet-radiochemistry to create a new platform for high-throughput experimentation in radiochemistry. This system contains an array of 4 heaters, each used to heat a set of 16 reactions on a small chip, enabling 64 parallel reactions for the rapid optimization of conditions in any stage of a multi-step radiosynthesis process. As examples, we study the syntheses of several 18F-labeled radiopharmaceuticals ([18F]Flumazenil, [18F]PBR06, [18F]Fallypride, and [18F]FEPPA), performing > 800 experiments to explore the influence of parameters including base type, base amount, precursor amount, solvent, reaction temperature, and reaction time. The experiments were carried out within only 15 experiment days, and the small volume (~ 10 µL compared to the ~ 1 mL scale of conventional instruments) consumed ~ 100 × less precursor per datapoint. This new method paves the way for more comprehensive optimization studies in radiochemistry and substantially shortening PET tracer development timelines.

Optimization of Radiochemical Reactions using Droplet Arrays.

Current automated radiosynthesizers are designed to produce large clinical batches of radiopharmaceuticals. They are not well suited for reaction optimization or novel radiopharmaceutical development since each data point involves significant reagent consumption, and contamination of the apparatus requires time for radioactive decay before the next use. To address these limitations, a platform for performing arrays of miniature droplet-based reactions in parallel, each confined within a surface-tension trap on a patterned polytetrafluoroethylene-coated silicon "chip", was developed. These chips enable rapid and convenient studies of reaction parameters including reagent concentrations, reaction solvent, reaction temperature and time. This platform permits the completion of hundreds of reactions in a few days with minimal reagent consumption, instead of taking months using a conventional radiosynthesizer.

Green and efficient synthesis of the radiopharmaceutical [18F]FDOPA using a microdroplet reactor.

From an efficiency standpoint, microdroplet reactors enable significant improvements in the preparation of radiopharmaceuticals due to the vastly reduced reaction volume. To demonstrate these advantages, we adapt the conventional (macroscale) synthesis of the clinically-important positron-emission tomography tracer [18F]FDOPA, following the nucleophilic diaryliodonium salt approach, to a newly-developed ultra-compact microdroplet reaction platform. In this first microfluidic implementation of [18F]FDOPA synthesis, optimized via a high-throughput multi-reaction platform, the radiochemical yield (non-decay-corrected) was found to be comparable to macroscale reports, but the synthesis consumed significantly less precursor and organic solvents, and the synthesis process was much faster. In this initial report, we demonstrate the production of [18F]FDOPA in 15 MBq [400 µCi] amounts, sufficient for imaging of multiple mice, at high molar activity.

The Clinical Evaluation of Alcohol Intoxication Is Inaccurate in Trauma Patients.

BACKGROUND: Discharging patients from emergency centers based on the clinical features of intoxication alone may be dangerous, as these may poorly correlate with ethanol measurements. OBJECTIVE: We determined the feasibility of utilizing a hand-held breath alcohol analyzer to aid in the disposition of intoxicated trauma patients by comparing serial breathalyzer (Intoximeter, Alco-Sensor FST, St. Louis, Missouri, USA] data with clinical assessments in determining the readiness of trauma patients for discharge. METHODS: A total of 20 legally intoxicated (LI) patients (blood alcohol concentration (BAC) >80 mg/dL) brought to our trauma center were prospectively investigated. Serial breath samples were obtained using a breathalyzer as a surrogate measure of repeated BAC. A clinical exam (nystagmus, one-leg balance, heel-toe walk) was performed prior to each breath sampling. RESULTS: The enrollees were 85% male, age 30±10 (range 19-51), with a body mass index (BMI) of 29±7. The average initial body alcohol level (BAL) was 245±61 (range 162-370) mg/dL. Based on breath samples, the alcohol elimination rates varied from 21.5 mg/dL/hr to 45.7 mg/dL/hr (mean 28.5 mg/dL/hr). There were no significant differences in alcohol elimination rates by gender, age, or BMI. The clinical exam also varied widely among patients; only seven of 16 (44%) LI patients demonstrated horizontal nystagmus (suggesting sobriety when actually LI) and the majority of the LI patients (66%) were able to complete the balance tasks (suggesting sobriety). CONCLUSION: Intoxicated trauma patients have an unreliable clinical sobriety exam and a wide range of alcohol elimination rates. The portable alcohol breath analyzer represents a potential option to easily and inexpensively establish legal sobriety in this population.

Electrochemical Flash Fluorination and Radiofluorination.

A new method for rapid late-stage fluorination using the cation pool technique is presented. Fluorination and no-carrier-added radiofluorination of methyl (phenylthio) acetate, methyl 2-(methylthio) acetate, and methyl 2-(ethylthio) acetate were performed. The carbocations formed through electrochemical oxidation were stabilized by using a divided electrochemical cell and 2,2,2-trifluoroethanol (TFE) as the solvent at -20 °C. At the end of electrolysis, either stable-isotope [19F]fluoride or no-carrier-added radioactive [18F]fluoride was added to the reaction mixture to form the fluorinated or radiofluorinated product.

Dermal γδ T-Cells Can Be Activated by Mitochondrial Damage-Associated Molecular Patterns.

BACKGROUND: Gamma delta T-cells have been shown to be important to the early immunoinflammatory response to injury, independent of infection. This unique T-cell population acts to regulate cell trafficking and the release of cytokines and growth factors. We propose this sterile inflammatory response is in part associated with damage associated molecular patterns (DAMPs) generated by major injury, such as burn, and mediated via toll-like receptors (TLRs). It is unknown whether DAMPs can activate resident γδ T-cells that reside in skin. METHODS: Gamma delta T-cells were isolated from the skin of male C57BL/6 mice by enzymatic digestion. Mitochondrial DAMPs (MTDs) were generated from mitochondria isolated from mouse livers by sonication and centrifugation. Dermal γδ T-cells were incubated with MTDs (0-500 µg/ml) for 24 hr and cells and supernatants were collected for analysis. RESULTS: MTDs activated dermal γδ T-cells, as evidenced by increased TLR2 and TLR4 expression following in vitro exposure. MTDs also induced the production of inflammatory cytokines (IL-1ß, IL-6), and growth factors (PDGF and VEGF) by γδ T-cells. CONCLUSIONS: These findings herein support the concept that MTDs released after tissue/cellular injury are capable of activating dermal γδ T-cells. We propose that the activation of this unique T-cell population is central in the initiation of sterile inflammation and also contributes to the subsequent healing processes.

Small Bowel Perforations by Metallic Grill Brush Bristles: Clinical Presentations and Opportunity for Prevention.

Increasing reports on the incidental ingestion of metallic bristles from barbeque grill cleaning brushes have been reported. We sought to describe the clinical presentation and grilling habits of patients presenting after ingesting metallic bristles in an attempt to identify risk factors. We performed a chart review of six patients with documented enteric injury from metallic bristles. Subjects were contacted and administered a survey focused on the events surrounding the bristle ingestion. We arranged for in-home visits to inspect the grill and grill brush whenever possible. Of the six subjects identified, three (50%) were male, five (83%) were white, and they ranged in age from 18 to 65 years (mean 42.5). All complained of abdominal pain. All bristles were identified by CT scan. Three patients underwent laparoscopic enterorrhaphy, and two underwent laparotomy. The remaining patients did not require intervention. None had replaced their grill brush in at least two years. Surgeon's awareness of this unusual injury is important to identify and manage this problem. Alternative methods to clean the grill should be sought and grill brushes should be replaced at least every two years.

The contribution of opiate analgesics to the development of infectious complications in trauma patients.

Trauma-related pain is a natural consequence of injury and its surgical management; however, the relationship between opiates and complications in trauma patients is unknown. To study this a retrospective chart review of selected subjects following traumatic injury with admission to the SICU for > 3 days was performed, and opiate administration data was collected for the first 3 days of admission. Associated data from each subject's chart was also collected. Analysis of the data revealed that increased opiate intake after admission to the SICU was associated with significantly increased SICU and hospital LOS independent of injury severity. This increase in LOS was independent of mechanical ventilation in the moderate ISS group. Infectious complications were also more prevalent in the moderate ISS group with higher opiate use. These findings suggest that increased doses of opiate analgesics in trauma patients may contribute to an increased overall LOS and associated infectious complications. Analgesic regimes that minimize opiate intake, while still providing adequate pain relief, may be advantageous in reducing LOS, complications and reduce hospitalization costs.

The Th-17 response and its potential role in post-injury pulmonary complications.

Trauma is a leading cause of death and morbidity among all ages and constitutes a major public health problem. This burden is initially directed at stabilizing direct injury, however, post-trauma complications are common and prolong costly ICU stays. Among these complications are acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). While care for these pulmonary complications has now been standardized and prevention continues to improve, the true pathophysiology has not been elucidated. Current evidence suggests that the activation of a pro-inflammatory cascade plays an important role in the pathogenesis of trauma related lung injury. Additionally, there is a novel T-cell response that has been shown to be intricately involved in other non-traumatic lung diseases and multiple inflammatory diseases. With the recent discovery of this novel T-helper subset (Th-17) and the main effector cytokine, IL-17, there is the potential for further categorizing the biologic mechanism leading to ALI and ARDS. By utilizing the discoveries provided by animal models and further investigation into local and systemic cytokine profiles in human trauma victims, the information gained holds promise in the development of unique therapeutic modalities for the treatment and prevention of ARDS following traumatic injury.