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Hu C, Qiu Y, Guo J, Cao Y, Li D, Du Y. An Oxygen Supply Strategy for Sonodynamic Therapy in Tuberculous Granuloma Lesions Using a Catalase-Loaded Nanoplatform. Int J Nanomedicine 2023; 18:6257-6274. [PMID: 37936950 PMCID: PMC10627092 DOI: 10.2147/ijn.s430019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 10/11/2023] [Indexed: 11/09/2023] Open
Abstract
Purpose Tuberculosis (TB) is a chronic disease caused by Mycobacterium tuberculosis (MTB) that remains a major global health challenge. One of the main obstacles to effective treatment is the heterogeneous microenvironment of TB granulomas. This study aimed to investigate the potential of a hypoxic remission-based strategy to enhance the outcome of tuberculosis treatment when implemented in combination with ultrasound. Methods A PLGA nanoparticle (LEV@CAT-NPs) loaded with levofloxacin (LEV) and catalase (CAT) was fabricated by a double emulsification method, and its physical characteristics, oxygen production capacity, drug release capacity, and biosafety were thoroughly investigated. The synergistic therapeutic effects of ultrasound (US)-mediated LEV@CAT-NPs were evaluated using an experimental mouse model of subcutaneous tuberculosis granuloma induced by Bacille Calmette-Guérin (BCG) as a substitute for MTB. Results LEV@CAT-NPs exhibited excellent oxygen production capacity, biosafety, and biocompatibility. Histological analysis revealed that ultrasound-mediated LEV@CAT-NPs could effectively remove bacteria from tuberculous granulomas, significantly alleviate the hypoxia state, reduce the necrotic area and inflammatory cells within the granuloma, and increase the penetration of dyes in granuloma tissues. The combined treatment also reduced the serum levels of inflammatory cytokines (eg, TNF-α, IL-6, and IL-8), and significantly downregulated the expression of hypoxia-inducible factor 1α (HIF-1α) and vascular endothelial growth factor (VEGF). These results suggested that the synergistic treatment of ultrasound-mediated LEV@CAT-NPs effectively eradicated the bacterial infection and reversed the hypoxic microenvironment of tuberculous granulomas, further promoting tissue repair. Conclusion This study provides a non-invasive and new avenue for treating refractory tuberculosis infections. The potential role of regulating hypoxia within infected lesions as a therapeutic target for infection deserves further exploration in future studies.
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Affiliation(s)
- Can Hu
- State Key Laboratory of Ultrasound in Medicine and Engineering, College of Biomedical Engineering, Chongqing Medical University, Chongqing, 400016, People’s Republic of China
- Chongqing Key Laboratory of Biomedical Engineering, Chongqing Medical University, Chongqing, 400016, People’s Republic of China
| | - Yan Qiu
- State Key Laboratory of Ultrasound in Medicine and Engineering, College of Biomedical Engineering, Chongqing Medical University, Chongqing, 400016, People’s Republic of China
- Chongqing Key Laboratory of Biomedical Engineering, Chongqing Medical University, Chongqing, 400016, People’s Republic of China
| | - Jiajun Guo
- State Key Laboratory of Ultrasound in Medicine and Engineering, College of Biomedical Engineering, Chongqing Medical University, Chongqing, 400016, People’s Republic of China
- Chongqing Key Laboratory of Biomedical Engineering, Chongqing Medical University, Chongqing, 400016, People’s Republic of China
| | - Yuchao Cao
- State Key Laboratory of Ultrasound in Medicine and Engineering, College of Biomedical Engineering, Chongqing Medical University, Chongqing, 400016, People’s Republic of China
- Chongqing Key Laboratory of Biomedical Engineering, Chongqing Medical University, Chongqing, 400016, People’s Republic of China
| | - Dairong Li
- Department of Respiratory and Critical Care Medicine, the First Affiliated Hospital of Chongqing Medical University, Chongqing, 400016, People’s Republic of China
| | - Yonghong Du
- State Key Laboratory of Ultrasound in Medicine and Engineering, College of Biomedical Engineering, Chongqing Medical University, Chongqing, 400016, People’s Republic of China
- Chongqing Key Laboratory of Biomedical Engineering, Chongqing Medical University, Chongqing, 400016, People’s Republic of China
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Mittal S, Mallia MB. Molecular imaging of tumor hypoxia: Evolution of nitroimidazole radiopharmaceuticals and insights for future development. Bioorg Chem 2023; 139:106687. [PMID: 37406518 DOI: 10.1016/j.bioorg.2023.106687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 06/15/2023] [Indexed: 07/07/2023]
Abstract
Though growing evidence has been collected in support of the concept of dose escalation based on the molecular level images indicating hypoxic tumor sub-volumes that could be radio-resistant, validation of the concept is still a work in progress. Molecular imaging of tumor hypoxia using radiopharmaceuticals is expected to provide the required input to plan dose escalation through Image Guided Radiation Therapy (IGRT) to kill/control the radio-resistant hypoxic tumor cells. The success of the IGRT, therefore, is heavily dependent on the quality of images obtained using the radiopharmaceutical and the extent to which the image represents the true hypoxic status of the tumor in spite of the heterogeneous nature of tumor hypoxia. Available literature on radiopharmaceuticals for imaging hypoxia is highly skewed in favor of nitroimidazole as the pharmacophore given their ability to undergo oxygen dependent reduction in hypoxic cells. In this context, present review on nitroimidazole radiopharmaceuticals would be immensely helpful to the researchers to obtain a birds-eye view on what has been achieved so far and what can be tried differently to obtain a better hypoxia imaging agent. The review also covers various methods of radiolabeling that could be utilized for developing radiotracers for hypoxia targeting applications.
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Affiliation(s)
- Sweety Mittal
- Radiopharmaceuticals Division, Bhabha Atomic Research Center, Mumbai 400085, India.
| | - Madhava B Mallia
- Radiopharmaceuticals Division, Bhabha Atomic Research Center, Mumbai 400085, India; Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India.
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Vorster M. Gallium-68 Labelled Radiopharmaceuticals for Imaging Inflammatory Disorders. Semin Nucl Med 2023; 53:199-212. [PMID: 36270829 DOI: 10.1053/j.semnuclmed.2022.08.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 08/18/2022] [Accepted: 08/22/2022] [Indexed: 12/24/2022]
Abstract
Inflammation is an important component of several chronic and debilitating diseases that result in significant morbidity and mortality. This is best evidenced within the cardiovascular system where it may manifest as atherosclerosis or myocarditis, and at the extreme end of the spectrum as myocardial infarction, ventricular remodeling, or cardiac failure. Early non-invasive detection and monitoring of inflammation in these and other settings may better guide patient management with resultant improved outcomes. Key role players in inflammation pathophysiology include chemokines, macrophages, neutrophils, fibroblasts, integrins, and reactive oxygen species, amongst others. Examples of receptor expression and over-expression include somatostatin receptors, CXCR4-, folate-, mannose-, TSPO- receptors and secretion of various vascular adhesion molecules (such as VCAM and ICAM). Gallium-68-based PET offers imaging possibilities for nearly all the major pathophysiological role players in inflammation, with mounting recent interest in macrophage differentiation, various forms of receptor expression and secretion of chemokines and vascular adhesion molecules. The advantages in terms of logistics and costs of having generator-produced PET probes available is well known, and a 68Ga-based tracer provides easily translatable theranostic possibilities to especially Lu-177. Some of the more versatile and better validated Ga-68-based inflammation probes include 68Ga-DOTA-TATE/NOC/TOC, 68Ga-NOTA-RGD, 68Ga-CXCR4, 68Ga-citrate and 68Ga-FAPI.
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Affiliation(s)
- Mariza Vorster
- Nuclear Medicine, Department of Nuclear Medicine at Inkosi Albert Luthuli Hospital, University of KwaZulu-Natal, Berea, KwaZulu-Natal, South Africa.
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Gouel P, Decazes P, Vera P, Gardin I, Thureau S, Bohn P. Advances in PET and MRI imaging of tumor hypoxia. Front Med (Lausanne) 2023; 10:1055062. [PMID: 36844199 PMCID: PMC9947663 DOI: 10.3389/fmed.2023.1055062] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 01/30/2023] [Indexed: 02/11/2023] Open
Abstract
Tumor hypoxia is a complex and evolving phenomenon both in time and space. Molecular imaging allows to approach these variations, but the tracers used have their own limitations. PET imaging has the disadvantage of low resolution and must take into account molecular biodistribution, but has the advantage of high targeting accuracy. The relationship between the signal in MRI imaging and oxygen is complex but hopefully it would lead to the detection of truly oxygen-depleted tissue. Different ways of imaging hypoxia are discussed in this review, with nuclear medicine tracers such as [18F]-FMISO, [18F]-FAZA, or [64Cu]-ATSM but also with MRI techniques such as perfusion imaging, diffusion MRI or oxygen-enhanced MRI. Hypoxia is a pejorative factor regarding aggressiveness, tumor dissemination and resistance to treatments. Therefore, having accurate tools is particularly important.
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Affiliation(s)
- Pierrick Gouel
- Département d’Imagerie, Centre Henri Becquerel, Rouen, France,QuantIF-LITIS, EA 4108, IRIB, Université de Rouen, Rouen, France
| | - Pierre Decazes
- Département d’Imagerie, Centre Henri Becquerel, Rouen, France,QuantIF-LITIS, EA 4108, IRIB, Université de Rouen, Rouen, France
| | - Pierre Vera
- Département d’Imagerie, Centre Henri Becquerel, Rouen, France,QuantIF-LITIS, EA 4108, IRIB, Université de Rouen, Rouen, France
| | - Isabelle Gardin
- Département d’Imagerie, Centre Henri Becquerel, Rouen, France,QuantIF-LITIS, EA 4108, IRIB, Université de Rouen, Rouen, France
| | - Sébastien Thureau
- QuantIF-LITIS, EA 4108, IRIB, Université de Rouen, Rouen, France,Département de Radiothérapie, Centre Henri Becquerel, Rouen, France
| | - Pierre Bohn
- Département d’Imagerie, Centre Henri Becquerel, Rouen, France,QuantIF-LITIS, EA 4108, IRIB, Université de Rouen, Rouen, France,*Correspondence: Pierre Bohn,
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Lawal IO, Abubakar S, Ankrah AO, Sathekge MM. Molecular Imaging of Tuberculosis. Semin Nucl Med 2023; 53:37-56. [PMID: 35882621 DOI: 10.1053/j.semnuclmed.2022.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 07/05/2022] [Indexed: 01/28/2023]
Abstract
Despite the introduction of many novel diagnostic techniques and newer treatment agents, tuberculosis (TB) remains a major cause of death from an infectious disease worldwide. With about a quarter of humanity harboring Mycobacterium tuberculosis, the causative agent of TB, the current efforts geared towards reducing the scourge due to TB must be sustained. At the same time, newer alternative modalities for diagnosis and treatment response assessment are considered. Molecular imaging entails the use of radioactive probes that exploit molecular targets expressed by microbes or human cells for imaging using hybrid scanners that provide both anatomic and functional features of the disease being imaged. Fluorine-18 fluorodeoxyglucose (FDG) is the most investigated radioactive probe for TB imaging in research and clinical practice. When imaged with positron emission tomography interphase with computed tomography (PET/CT), FDG PET/CT performs better than sputum conversion for predicting treatment outcome. At the end of treatment, FDG PET/CT has demonstrated the unique ability to identify a subset of patients declared cured based on the current standard of care but who still harbor live bacilli capable of causing disease relapse after therapy discontinuation. Our understanding of the pathogenesis and evolution of TB has improved significantly in the last decade, owing to the introduction of FDG PET/CT in TB research. FDG is a non-specific probe as it targets the host inflammatory response to Mycobacterium tuberculosis, which is not specifically different in TB compared with other infectious conditions. Ongoing efforts are geared towards evaluating the utility of newer probes targeting different components of the TB granuloma, the hallmark of TB lesions, including hypoxia, neovascularization, and fibrosis, in TB management. The most exciting category of non-FDG PET probes developed for molecular imaging of TB appears to be radiolabeled anti-tuberculous drugs for use in studying the pharmacokinetic characteristics of the drugs. This allows for the non-invasive study of drug kinetics in different body compartments concurrently, providing an insight into the spatial heterogeneity of drug exposure in different TB lesions. The ability to repeat molecular imaging using radiolabeled anti-tuberculous agents also offers an opportunity to study the temporal changes in drug kinetics within the different lesions during treatment.
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Affiliation(s)
- Ismaheel O Lawal
- Division of Nuclear Medicine and Molecular Imaging, Department of Radiology and Imaging Sciences, Emory University, Atlanta, GA; Department of Nuclear Medicine, University of Pretoria, Pretoria, Gauteng, South Africa.
| | - Sofiullah Abubakar
- Department of Radiology and Nuclear Medicine, Sultan Qaboos Comprehensive Cancer Care and Research Center, Muscat, Oman
| | - Alfred O Ankrah
- Department of Nuclear Medicine, University of Pretoria, Pretoria, Gauteng, South Africa; National Center for Radiotherapy Oncology and Nuclear Medicine, Korle Bu Teaching Hospital, Accra, Ghana; Medical Imaging Center, Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, Groningen, The Netherlands
| | - Mike M Sathekge
- Department of Nuclear Medicine, University of Pretoria, Pretoria, Gauteng, South Africa; Nuclear Medicine Research Infrastructure (NuMeRI), Steve Biko Academic Hospital, Pretoria, South Africa
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Gouws AC, Kruger HG, Gheysens O, Zeevaart JR, Govender T, Naicker T, Ebenhan T. Antibiotic-Derived Radiotracers for Positron Emission Tomography: Nuclear or "Unclear" Infection Imaging? Angew Chem Int Ed Engl 2022; 61:e202204955. [PMID: 35834311 PMCID: PMC9826354 DOI: 10.1002/anie.202204955] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Indexed: 01/11/2023]
Abstract
The excellent features of non-invasive molecular imaging, its progressive technology (real-time, whole-body imaging and quantification), and global impact by a growing infrastructure for positron emission tomography (PET) scanners are encouraging prospects to investigate new concepts, which could transform clinical care of complex infectious diseases. Researchers are aiming towards the extension beyond the routinely available radiopharmaceuticals and are looking for more effective tools that interact directly with causative pathogens. We reviewed and critically evaluated (challenges or pitfalls) antibiotic-derived PET radiopharmaceutical development efforts aimed at infection imaging. We considered both radiotracer development for infection imaging and radio-antibiotic PET imaging supplementing other tools for pharmacologic drug characterization; overall, a total of 20 original PET radiotracers derived from eleven approved antibiotics.
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Affiliation(s)
- Arno Christiaan Gouws
- Catalysis and Peptide Research UnitUniversity of KwaZulu-NatalDurban4000South Africa
| | | | - Olivier Gheysens
- Department of Nuclear MedicineCliniques Universitaires Saint-Luc, and Institute of Clinical and Experimental ResearchUniversité Catholique de LouvainBrusselsBelgium
| | - Jan Rijn Zeevaart
- Nuclear Medicine Research Infrastructure NPCPretoria0001South Africa
- RadiochemistryThe South African Nuclear Energy CorporationBrits0420South Africa
- Preclinical Drug Development PlatformNorth West UniversityPotchefstroom2520South Africa
| | | | - Tricia Naicker
- Catalysis and Peptide Research UnitUniversity of KwaZulu-NatalDurban4000South Africa
| | - Thomas Ebenhan
- Nuclear Medicine Research Infrastructure NPCPretoria0001South Africa
- Preclinical Drug Development PlatformNorth West UniversityPotchefstroom2520South Africa
- Department of Nuclear MedicineUniversity of PretoriaPretoria0001South Africa
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7
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Gouws AC, Kruger HG, Gheysens O, Zeevaart JR, Govender T, Naiker T, Ebenhan T. Antibiotic‐Derived Radiotracers for Positron Emission Tomography: Nuclear or ‘Unclear’ Infection Imaging? Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202204955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Arno Christiaan Gouws
- University of KwaZulu-Natal School of Health Sciences Catalysis and Peptide Research Unit SOUTH AFRICA
| | - Hendrik Gerhardus Kruger
- University of KwaZulu-Natal School of Health Sciences Catalysis and Peptide Research Unit SOUTH AFRICA
| | - Olivier Gheysens
- Cliniques Universitaires Saint-Luc Department of Nuclear Medicine BELGIUM
| | - Jan Rijn Zeevaart
- North-West University Potchefstroom Campus: North-West University Preclinical Drug Development Platform SOUTH AFRICA
| | | | - Tricia Naiker
- University of KwaZulu-Natal School of Health Sciences Catalysis and Peptide Research Unit SOUTH AFRICA
| | - Thomas Ebenhan
- University of Pretoria Nuclear Medicine Steve Biko and Malherbe St 0001 Pretoria SOUTH AFRICA
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Bresser PL, Sathekge MM, Vorster M. PET/CT features of a novel gallium-68 labelled hypoxia seeking agent in patients diagnosed with tuberculosis: a proof-of-concept study. Nucl Med Commun 2022; 43:787-793. [PMID: 35506285 DOI: 10.1097/mnm.0000000000001580] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
INTRODUCTION Positron emission tomography/computed tomography (PET/CT) in infection and inflammation has yielded promising results across a range of radiopharmaceuticals. In particular, PET/CT imaging of tuberculosis (TB) allows for a better understanding of this complex disease by providing insights into molecular processes within the TB microenvironment. TB lesions are hypoxic with research primarily focussed on cellular processes occurring under hypoxic stress. With the development of hypoxia seeking PET/CT radiopharmaceuticals, that can be labelled in-house using a germanium-68/gallium-68 (68Ge/68Ga) generator, a proof-of-concept for imaging hypoxia in TB is presented. METHODS Ten patients diagnosed with TB underwent whole-body PET/CT imaging, 60-90 min after intravenous administration of 74-185 MBq (2-5 mCi) 68Ga-nitroimidazole. No oral or intravenous contrast was administered. Images were visually and semiquantitatively assessed for abnormal 68Ga-uptake in the lungs. RESULTS A total of 28 lesions demonstrating hypoxic uptake were identified. Low- to moderate-uptake was seen in nodules, areas of consolidation and cavitation as well as effusions. The mean standard uptake value (SUVmean) of the lesions was 0.47 (IQR, 0.32-0.82) and SUVmax was 0.71 (IQR, 0.41-1.11). The lesion to muscle ratio (median, 1.70; IQR, 1.15-2.31) was higher than both the left ventricular and the aorta lesion to blood ratios. CONCLUSION Moving towards the development of unique host-directed therapies (HDT), modulation of oxygen levels may improve therapeutic outcome by reprogramming TB lesions to overcome hypoxia. This proof-of-concept study suggests that hypoxia in TB lesions can be imaged and quantified using 68Ga-nitroimidazole PET/CT. Subsequently, hypoxic load can be estimated to inform personalised treatment plans of patients diagnosed with TB.
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Affiliation(s)
- Philippa L Bresser
- Department of Nuclear Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
- Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Mike M Sathekge
- Department of Nuclear Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - Mariza Vorster
- Department of Nuclear Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
- Department of Nuclear Medicine, Inkosi Albert Luthuli Central Hospital, University of Kwazulu Natal, Durban, South Africa
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Bresser PL, Reed J, Sathekge MM, Vorster M. 68 Ga-nitroimidazole PET/CT imaging of hypoxia in tuberculosis: A case series. J Med Radiat Sci 2022; 69:518-524. [PMID: 35760568 DOI: 10.1002/jmrs.603] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 06/02/2022] [Indexed: 12/19/2022] Open
Abstract
Tuberculosis (TB) lesions in humans have been proven to be severely hypoxic with hypoxia leading to latency and dormancy of disease. Dormant TB lesions become less susceptible to standard TB treatment regimens with varying responses to treatment but may have increased susceptibility to nitroimidazole drugs. This in turn implies that positron emission tomography / computed tomography (PET/CT) imaging with radiolabelled nitroimidazoles may identify patients who will benefit from treatment with antimicrobial agents that are active against anaerobic bacteria. This case series aims to highlight the hypoxic uptake and retention of a novel 68 Ga-labelled hypoxia-seeking agent in TB lesions at different time points during anti-TB therapy using PET/CT imaging. Patients with confirmed TB underwent whole-body PET/CT after administration of a 68 Ga-nitroimidazole derivative at baseline and follow-up. Images were analysed both qualitatively and semi-quantitatively. Hypoxic uptake and change in uptake over time were analysed using lesion-to-muscle ratio (LMR) and lesion-to-blood ratio (LBR). 68 Ga-nitroimidazole avid lesions were demonstrated most frequently in the upper lobes of the lung. Low-grade hypoxic uptake was visualised in areas of consolidation, cavitation, nodules and lymph nodes. From baseline to follow-up imaging, the LMR increased with persistent hypoxic load despite morphologic improvement. This case series highlights the dynamic hypoxic microenvironment in TB lesions. From these initial data, it appears that 68 Ga-nitroimidazole is a promising candidate for monitoring hypoxic load in patients diagnosed with TB. Such imaging could identify patients who would benefit from individualised therapy targeting other mechanisms in the TB microenvironment with the intention to predict or improve treatment response.
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Affiliation(s)
- Philippa L Bresser
- Department of Nuclear Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa.,Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Janet Reed
- Department of Nuclear Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - Mike M Sathekge
- Department of Nuclear Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - Mariza Vorster
- Department of Nuclear Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa.,Department of Nuclear Medicine, Inkosi Albert Luthuli Central Hospital, University of Kwazulu-Natal, Durban, South Africa
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More S, Marakalala MJ, Sathekge M. Tuberculosis: Role of Nuclear Medicine and Molecular Imaging With Potential Impact of Neutrophil-Specific Tracers. Front Med (Lausanne) 2021; 8:758636. [PMID: 34957144 PMCID: PMC8703031 DOI: 10.3389/fmed.2021.758636] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Accepted: 11/03/2021] [Indexed: 01/02/2023] Open
Abstract
With Tuberculosis (TB) affecting millions of people worldwide, novel imaging modalities and tools, particularly nuclear medicine and molecular imaging, have grown with greater interest to assess the biology of the tuberculous granuloma and evolution thereof. Much early work has been performed at the pre-clinical level using gamma single photon emission computed tomography (SPECT) agents exploiting certain characteristics of Mycobacterium tuberculosis (MTb). Both antituberculous SPECT and positron emission tomography (PET) agents have been utilised to characterise MTb. Other PET tracers have been utilised to help to characterise the biology of MTb (including Gallium-68-labelled radiopharmaceuticals). Of all the tracers, 2-[18F]FDG has been studied extensively over the last two decades in many aspects of the treatment paradigm of TB: at diagnosis, staging, response assessment, restaging, and in potentially predicting the outcome of patients with latent TB infection. Its lower specificity in being able to distinguish different inflammatory cell types in the granuloma has garnered interest in reviewing more specific agents that can portend prognostic implications in the management of MTb. With the neutrophil being a cell type that portends this poorer prognosis, imaging this cell type may be able to answer more accurately questions relating to the tuberculous granuloma transmissivity and may help in characterising patients who may be at risk of developing active TB. The formyl peptide receptor 1(FPR1) expressed by neutrophils is a key marker in this process and is a potential target to characterise these areas. The pre-clinical work regarding the role of radiolabelled N-cinnamoyl –F-(D) L – F – (D) –L F (cFLFLF) (which is an antagonist for FPR1) using Technetium 99m-labelled conjugates and more recently radiolabelled with Gallium-68 and Copper 64 is discussed. It is the hope that further work with this tracer may accelerate its potential to be utilised in responding to many of the current diagnostic dilemmas and challenges in TB management, thereby making the tracer a translatable option in routine clinical care.
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Affiliation(s)
- Stuart More
- Division of Nuclear Medicine, Department of Radiation Medicine, University of Cape Town, Cape Town, South Africa
- Department of Nuclear Medicine, University of Pretoria and Steve Biko Academic Hospital, Pretoria, South Africa
- Nuclear Medicine Research Infrastructure, Steve Biko Academic Hospital, Pretoria, South Africa
- *Correspondence: Stuart More
| | - Mohlopheni J. Marakalala
- Africa Health Research Institute, Durban, South Africa
- Division of Infection and Immunity, University College London, London, United Kingdom
- School of Laboratory Medicine and Medical Sciences, College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
- Division of Immunology, Department of Pathology, University of Cape Town, Cape Town, South Africa
| | - Michael Sathekge
- Department of Nuclear Medicine, University of Pretoria and Steve Biko Academic Hospital, Pretoria, South Africa
- Nuclear Medicine Research Infrastructure, Steve Biko Academic Hospital, Pretoria, South Africa
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