Activated neutrophil fluorescent imaging technique for human lungs

Phase 0 trials/ Intra-Target-Microdosing (ITM) and the lung: a review

The COVID-19 pandemic has highlighted the importance of efficient drug discovery in respiratory disease. The traditional set up of clinical trials is expensive and allows for significant attrition of new drugs, many of which undergo extensive safety testing before being abandoned for lack of efficacy. Phase 0 trials, named as they sit between pre-clinical research and phase I, allow for the testing of sub-clinical microdoses in humans to gather early pharmacokinetic (PK), pharmacodynamic (PD) and mechanistic data, before deciding on which drugs to advance further. This early data can improve the efficiency and cost effectiveness of drug development and reduce the extent of animal testing. Phase 0 trials traditionally have utilised sub-therapeutic microdoses of compounds administered intravenously with readouts focusing on PK - measured using highly sensitive methods such as accelerator mass spectrometry (AMS) and liquid chromatography tandem mass spectrometry (LC-MS/MS) of peripheral blood, as well as whole-body positron emission tomography (PET). Mathematical models allow for extrapolation of this PK data to support the further testing of larger, systemically effective doses. However, this extrapolation method is limited at providing robust PD or target engagement/ mode of action data. Using an Intra-Target Microdosing (ITM) approach, a small compartment of the body (about 1% or less) is exposed to potentially clinically active local concentrations. This allows for the collection of PD data, evidence of target cell engagement, as well as the opportunity to extrapolate systemic PK and PD data. This approach has the potential within the pulmonary system for the study and rapid and cost-effective development of new and repurposed drugs.

An actively stabilized, miniaturized epi-fluorescence widefield microscope for real-time observation in vivo

Recent developments in real-time, in vivo micro-imaging have allowed for the visualization of tissue pathological changes, facilitating rapid diagnosis. However, miniaturization, magnification, the field of view, and in vivo image stabilization remain challenging factors to reconcile. A key issue for this technology is ensuring it is user friendly for surgeons, enabling them to use the device manually and obtain instantaneous information necessary for surgical decision-making. This descriptive study introduces a handheld, actively stabilized, miniaturized epi-fluorescence widefield microscope (MEW-M) for real-time observation in vivo with high resolution. The methodology of MEW-M system includes high resolution microscopy miniaturization technology, thousandfold shaking suppression (actively stabilized), ultra-photosensitivity, and tailored image signal processing cell image capture and processing technology, which support for the excellent real-time imaging performance of MEW-M system in brain, mammary, liver, lung, and kidney tissue imaging of rats in vivo. With a single-objective and high-frame-rate imaging, the MEW-M system facilitates roving image acquisition, enabling contiguous analysis of large tissue areas. RESEARCH HIGHLIGHTS: A handheld, actively stabilized MEW-M system was introduced. Excellent real-time, in vivo imaging with high resolution and active stabilization in brain, mammary, liver, lung, and kidney tissue of rats.

Recent Advances in the Development of Non-Invasive Imaging Probes for Cancer Immunotherapy

The last two decades have witnessed a major revolution in the field of tumor immunology including clinical progress using various immunotherapy strategies. These advances have highlighted the potential for approaches that harness the power of the immune system to fight against cancer. While cancer immunotherapies have shown significant clinical successes, patient responses vary widely due to the complex and heterogeneous nature of tumors and immune responses, calling for reliable biomarkers and therapeutic strategies to maximize the benefits of immunotherapy. Especially, stratifying responding individuals from non-responders during the early stages of treatment could help avoid long-term damage and tailor personalized treatments. In efforts to develop non-invasive means for accurately evaluating and predicting tumor response to immunotherapy, multiple affinity-based agents targeting immune cell markers and checkpoint molecules have been developed and advanced to clinical trials. In addition, researchers have recently turned their attention to substrate and activity-based imaging probes that can provide real-time, functional assessment of immune response to treatment. Here, we highlight some of those recently designed probes that image functional proteases as biomarkers of cancer immunotherapy with a focus on their chemical design and detection modalities and discuss challenges and opportunities for the development of imaging tools utilized in cancer immunotherapy.

Molecular Imaging of Innate Immunity and Immunotherapy

The innate immune system plays a key role as the first line of defense in various human diseases including cancer, cardiovascular and inflammatory diseases. In contrast to tissue biopsies and blood biopsies, in vivo imaging of the innate immune system can provide whole body measurements of immune cell location and function and changes in response to disease progression and therapy. Rationally developed molecular imaging strategies can be used in evaluating the status and spatio-temporal distributions of the innate immune cells in near real-time, mapping the biodistribution of novel innate immunotherapies, monitoring their efficacy and potential toxicities, and eventually for stratifying patients that are likely to benefit from these immunotherapies. In this review, we will highlight the current state-of-the-art in noninvasive imaging techniques for preclinical imaging of the innate immune system particularly focusing on cell trafficking, biodistribution, as well as pharmacokinetics and dynamics of promising immunotherapies in cancer and other diseases; discuss the unmet needs and current challenges in integrating imaging modalities and immunology and suggest potential solutions to overcome these barriers.

Fluorescent Probes as a Tool in Diagnostic and Drug Delivery Systems

Over the last few years, the development of fluorescent probes has received considerable attention. Fluorescence signaling allows noninvasive and harmless real-time imaging with great spectral resolution in living objects, which is extremely useful for modern biomedical applications. This review presents the basic photophysical principles and strategies for the rational design of fluorescent probes as visualization agents in medical diagnosis and drug delivery systems. Common photophysical phenomena, such as Intramolecular Charge Transfer (ICT), Twisted Intramolecular Charge Transfer (TICT), Photoinduced Electron Transfer (PET), Excited-State Intramolecular Proton Transfer (ESIPT), Fluorescent Resonance Energy Transfer (FRET), and Aggregation-Induced Emission (AIE), are described as platforms for fluorescence sensing and imaging in vivo and in vitro. The presented examples are focused on the visualization of pH, biologically important cations and anions, reactive oxygen species (ROS), viscosity, biomolecules, and enzymes that find application for diagnostic purposes. The general strategies regarding fluorescence probes as molecular logic devices and fluorescence–drug conjugates for theranostic and drug delivery systems are discussed. This work could be of help for researchers working in the field of fluorescence sensing compounds, molecular logic gates, and drug delivery.

Specific in situ immuno-imaging of pulmonary-resident memory lymphocytes in human lungs

Introduction

Pulmonary-resident memory T cells (T_RM) and B cells (B_RM) orchestrate protective immunity to reinfection with respiratory pathogens. Developing methods for the in situ detection of these populations would benefit both research and clinical settings.

Methods

To address this need, we developed a novel in situ immunolabelling approach combined with clinic-ready fibre-based optical endomicroscopy (OEM) to detect canonical markers of lymphocyte tissue residency in situ in human lungs undergoing ex vivo lung ventilation (EVLV).

Results

Initially, cells from human lung digests (confirmed to contain T_RM/B_RM populations using flow cytometry) were stained with CD69 and CD103/CD20 fluorescent antibodies and imaged in vitro using KronoScan, demonstrating it's ability to detect antibody labelled cells. We next instilled these pre-labelled cells into human lungs undergoing EVLV and confirmed they could still be visualised using both fluorescence intensity and lifetime imaging against background lung architecture. Finally, we instilled fluorescent CD69 and CD103/CD20 antibodies directly into the lung and were able to detect T_RM/B_RM following in situ labelling within seconds of direct intra-alveolar delivery of microdoses of fluorescently labelled antibodies.

Discussion

In situ, no wash, immunolabelling with intra-alveolar OEM imaging is a novel methodology with the potential to expand the experimental utility of EVLV and pre-clinical models.

The role of confocal laser endomicroscopy in pulmonary medicine

Accurate diagnosis and subsequent therapeutic options in pulmonary diseases mainly rely on imaging methods and histological assessment. However, imaging examinations are hampered by the limited spatial resolution of images and most procedures that are related to histological assessment are invasive with associated complications. As a result, a high-resolution imaging technology - confocal laser endomicroscopy (CLE), which is at the forefront and enables real-time microscopic visualisation of the morphologies and architectures of tissues or cells - has been developed to resolve the clinical dilemma pertaining to current techniques. The current evidence has shown that CLE has the potential to facilitate advanced diagnostic capabilities, to monitor and to aid the tailored treatment regime for patients with pulmonary diseases, as well as to expand the horizon for unravelling the mechanism and therapeutic targets of pulmonary diseases. In the future, if CLE can be combined with artificial intelligence, early, rapid and accurate diagnosis will be achieved through identifying the images automatically. As promising as this technique may be, further investigations are required before it can enter routine clinical practice.

Clinical Study of Heart Failure with Left Ventricular Ejection Fraction Regimen Treated with Entresto

Heart failure is a group of syndromes caused by various cardiac structural or functional disorders leading to impaired ventricular filling and (or) ejection capacity. Because of decreased ventricular systolic function and impaired ejection function, the amount of cardiac output cannot meet the body's metabolic needs; organ and tissue blood perfusion is insufficient; at the same time, pulmonary circulation and (or) systemic circulation congestion; the clinical manifestations are mainly dyspnea and weakness but restricted physical activity and edema. Treatment of the disease should include preventing and delaying the onset of wails, relieving symptoms of clinical wails, improving its long-term prognosis, and reducing mortality. The aim of the study is to observe the efficacy and safety of Entresto in the treatment of left ventricular ejection fraction heart failure (HFpEF). Seventy-eight patients with HFpEF treated in our hospital from October 2017 to April 2018 were randomized into a treatment group (Entresto 50 mg + basic treatment, n = 39) and a control group (basic treatment, n = 39). The course of treatment was ten weeks. The levels of brain natriuretic peptide (BNP) and echocardiographic indicators (LVMI, LVEF, LVEDD, LVESD, E/E' Ratio, E/A ratio, DT), 6-minute walking test (6MWD), and Minnesota Quality of Life Scale (MLHFQ) were analyzed before and after treatment. LVMI, LVEF, LVEDD, LVESD, E/E' ratio, E/A ratio, DT, and BNP were all significantly improved in the Entresto group after treatment. In the control group, except for LVEDD, LVESD, the E/A ratio, and BNP, other indicators were significantly improved after treatment (P < 0.05). Posttreatment, both groups had significantly improved 6MWD and MLHFQ scores (P < 0.05). Differences in these parameters between the two groups were statistically significant (P < 0.05). After treatment, the levels of NE, AngII, ALD, and MMP-9 in the two groups were decreased (P < 0.05), with the lower lever in the treatment group (P < 0.05). The effective rate was 76.92% in the control group and 94.87% in the Entresto group, and this rate difference was statistically significant (P < 0.05). The number of patients re-hospitalized due to cardiovascular events was 2 (the Entresto group) vs. 7 (the control group) cases; worsening of heart failure was observed in 1 patient (the Entresto group) vs. 6 (the control group), and the difference between the two groups was statistically significant (P < 0.05). However, the incidence of adverse reactions between the two groups was not statistically significant. Entresto can significantly improve left ventricular diastolic function in heart failure patients with preserved left ventricular ejection fraction and improve quality of life. This treatment is safe and effective and worthy of clinical application. This trail is registered with ChiCTR2000031486. This trial was approved by the Chinese Clinical Trial Registry (clinical trial number: ChiCTR2000031486). The registration number of this study is 2022-R008.

Review of the British Thoracic Society Winter Meeting 2021, 24-26 November 2021

The Winter Meeting of the British Thoracic Society (BTS) is a platform for the latest clinical and scientific research in respiratory medicine. This review summarises the key symposia and presentations from the BTS Winter Meeting 2021 held online due to the COVID-19 pandemic.

An Activatable Polymeric Nanoprobe for Fluorescence and Photoacoustic Imaging of Tumor-Associated Neutrophils in Cancer Immunotherapy

Imaging to evaluate tumor-associated neutrophils (TANs) is imperative for cancer immunotherapy but remains challenging. We herein report an activatable semiconducting polymer nanoprobe (SPCy) for near-infrared fluorescence (NIRF) and photoacoustic (PA) imaging of neutrophil elastase (NE), a biomarker of TANs. SPCy comprises a semiconducting polymer conjugated with a hemicyanine (hemi-Cy) dye caged by a NE-cleavable peptide as the side chain. After systemic administration, SPCy passively targets the tumor and reacts with NE to "uncage" the hemi-Cy, leading to enhanced NIRF and PA signals of the hemi-Cy but unchanged signals of the SP. Such NE-activated ratiometric NIRF and enhanced PA signals of SPCy correlate with the intratumoral population of TANs. Thus, this study not only presents the first TAN-specific PA probe, but also provides a general molecular design strategy for PA imaging of other immune-related biomarkers to facilitate screening of cancer immunotherapeutics.

Activatable Fluorophores for Imaging Immune Cell Function

Optical imaging has become an essential tool to study biomolecular processes in live systems with unprecedented spatial resolution. New fluorescent technologies and advances in optical microscopy have revolutionized the ways in which we can study immune cells in real time. For example, activatable fluorophores that emit signals after target recognition have enabled direct imaging of immune cell function with enhanced readouts and minimal background. In this Account, we summarize recent advances in the chemical synthesis and implementation of activatable fluorescent probes to monitor the activity and the role of immune cells in different pathological processes, from infection to inflammatory diseases or cancer. In addition to the contributions that our group has made to this field, we review the most relevant literature disclosed over the past decade, providing examples of different activatable architectures and their application in diagnostics and drug discovery. This Account covers the imaging of the three major cell types in the immune system, that is, neutrophils, macrophages, and lymphocytes. Attracted by the tunability and target specificity of peptides, many groups have designed strategies based on fluorogenic peptides whose fluorescence emission is regulated by the reaction with enzymes (e.g., MMPs, cathepsins, granzymes), or through Förster resonance energy transfer (FRET) mechanisms. Selective imaging of immune cells has been also achieved by targeting different intracellular metabolic routes, such as lipid biogenesis. Other approaches involve the implementation of diversity-oriented fluorescence libraries or the use of environmentally sensitive fluorescent scaffolds (e.g., molecular rotors). Our group has made important progress by constructing probes to image metastasis-associated macrophages in tumors, apoptotic neutrophils, or cytotoxic natural killer (NK) cells against cancer cells, among other examples. The chemical probes covered in this Account have been successfully validated in vitro in cell culture systems, and in vivo in relevant models of inflammation and cancer. Overall, the range of chemical structures and activation mechanisms reported to sense immune cell function is remarkable. However, the emergence of new strategies based on new molecular targets or activatable mechanisms that are yet to be discovered will open the door to track unexplored roles of immune cells in different biological systems. We anticipate that upcoming generations of activatable probes will find applications in the clinic to help assessing immunotherapies and advance precision medicine. We hope that this Account will evoke new ideas and innovative work in the design of fluorescent probes for imaging cell function.

Clinical Translation of Neutrophil Imaging and Its Role in Cancer

Neutrophils are the first line of defense against pathogens and abnormal cells. They regulate many biological processes such as infections and inflammation. Increasing evidence demonstrated a role for neutrophils in cancer, where different subpopulations have been found to possess both pro- or anti-tumorigenic functions in the tumor microenvironment. In this review, we discuss the phenotypic and functional diversity of neutrophils in cancer, their prognostic significance, and therapeutic relevance in human and preclinical models. Molecular imaging methods are increasingly used to probe neutrophil biology in vivo, as well as the cellular changes that occur during tumor progression and over the course of treatment. This review will discuss the role of neutrophil imaging in oncology and the lessons that can be drawn from imaging in infectious diseases and inflammatory disorders. The major factors to be considered when developing imaging techniques and biomarkers for neutrophils in cancer are reviewed. Finally, the potential clinical applications and the limitations of each method are discussed, as well as the challenges for future clinical translation.

Splenic T lymphocytes induce the formation of immunosuppressive neutrophils through IFN-γ in sepsis

BACKGROUND

Despite many advances in treatment, the prognosis of patients with sepsis still remains poor. Polymorphonuclear leukocytes (PMNs) are the first line of defense against infection. This study aimed to reveal the reason and mechanism of the production of PD-L1⁺ PMNs in sepsis.

METHODS

Cecal ligation and perforation mouse model was established to simulate sepsis. And PMNs were treated for 4 h, 12 h with or without 100 ng/mL (IFN-γ) for further gene sequencing. PD-L1, PD-1, Ly6G, and CD3 were detected by multiplexed immunofluorescence. In addition, expression of PD-L1 and function of PMNs were assessed by flow cytometry. Serum and cell culture supernatant were measured with ELISA assays. Western blot was used to verify the JAK2/STAT1 pathway.

RESULTS

Our study demonstrates that PMNs are the main immune cells with high expression of PD-L1 during sepsis, and these cells, therefore, play a critical role in immunosuppression. In vivo studies demonstrated a specific interaction between PD-L1⁺ PMNs and PD-1⁺ T cells. In vitro studies further demonstrated that IFN-γ induced the production of PD-L1⁺ PMNs through the JAK2/STAT1 pathway. In addition, Fedratinib, an inhibitor of Jak2, was shown to significantly reduce the expression of PD-L1 in neutrophils.

CONCLUSIONS

These data demonstrate that secretion of IFN-γ by splenic T lymphocytes induces the production of PD-L1 + PMNs through the JAK2/STAT1 pathway in sepsis.

Pulmonary-Resident Memory Lymphocytes: Pivotal Orchestrators of Local Immunity Against Respiratory Infections

There is increasing evidence that lung-resident memory T and B cells play a critical role in protecting against respiratory reinfection. With a unique transcriptional and phenotypic profile, resident memory lymphocytes are maintained in a quiescent state, constantly surveying the lung for microbial intruders. Upon reactivation with cognate antigen, these cells provide rapid effector function to enhance immunity and prevent infection. Immunization strategies designed to induce their formation, alongside novel techniques enabling their detection, have the potential to accelerate and transform vaccine development. Despite most data originating from murine studies, this review will discuss recent insights into the generation, maintenance and characterisation of pulmonary resident memory lymphocytes in the context of respiratory infection and vaccination using recent findings from human and non-human primate studies.