Discovering a New Drug Against Acute Kidney Injury by Using a Tailored Photoacoustic Imaging Probe

Bushen Jianpi Tiaoxue Decoction (BJTD) inhibits the LIF-mTOR signaling axis to regulate mitochondrial function and alleviate cyclophosphamide-induced diminished ovarian reserve

Diminished ovarian reserve (DOR) is a challenging obstacle impacting women' fertility globally with limited treatment option. Bushen Jianpi Tiaoxue Decoction (BJTD) has shown significant efficacy and safety in treating DOR patients, yet the molecular mechanisms behind its effect remain uncertain. Our study aimed to uncover the pharmacology and signaling pathway of BJTD in cyclophosphamide (Cy)-provoked DOR mice and 4-hydroperoxy cyclophosphamide (4-HC)-irritated KGN cells (human granulosa-like cell line) damage models. Granulosa cells from DOR patients and Cy-induced models were reanalyzed utilizing transcriptomics to predict differentially expressed genes and crucial signaling pathways. Validation experiments were conducted in vitro using KGN cells treated with 4-HC, a Cy metabolite, to establish a DOR model. Cell viability, apoptosis, oxidative stress, mitochondrial function, and ferroptosis markers were assessed using the cck8 assay, flow cytometry, fluorescence staining, RT-qPCR, and western blotting analyses. BJTD-serum was evaluated for its protective effects on 4-HC-triggered KGN damages. In vivo, a Cy-induced DOR mouse model was treated with BJTD to evaluate ovarian morphology, estrous cycle, follicle counts, hormone markers, mitochondrial apoptosis and ferroptosis levels, respectively via the vaginal smear, histological analysis, immunostaining, gene and protein expression experiments. The UPLC-MS analysis and network pharmacology were applied to identify BJTD's active ingredients, followed by molecular dockings to assess interactions with the target protein. To confirm the BJTD's mechanism of action, mTOR signaling modulation was analyzed using a specific inhibitor or activator in vitro. Transcriptomic reanalysis revealed significant gene expression differences, with LIF identified as a key target associated with apoptosis pathway. In vitro, 4-HC exposure induced apoptosis, mitochondrial dysfunction, and ferroptosis in KGN cells, accompanied by upregulation of LIF, mTOR, and FoxO3a signalings. BJTD-serum treatment significantly improved cell viability, reduced apoptosis, and alleviated oxidative stress by modulating mitochondrial function and ferroptosis markers, such as Nrf2, HO-1, and GPX4. In vivo, BJTD alleviated Cy-induced ovarian damage, improving ovarian index, estrous cycle, follicle development, and hormone levels, while reducing follicular atresia and granulosa cells apoptosis. Mechanically, BJTD suppressed Cy-induced activation of the LIF-mTOR axis and downstream mitochondrial apoptosis markers, including Cleaved Caspase 9/3, BAX, and γH2AX, while enhancing OPA1 and Bcl-2 expressions. The UPLC-MS outcome combining with network pharmacology identified mainly 20 active compounds in BJTD, with astragaloside IV exhibiting the strongest binding to the mTOR protein. The mTOR pathway modulation experiments confirmed that BJTD's protective effects are mediated through inhibition of hyperactivated mTOR phosphorylation and mitochondrial apoptosis cascades. BJTD demonstrates efficacy in alleviating Cy- and 4-HC-induced DOR models through targeting the LIF-mTOR signaling axis to suppress granulosa cells mitochondrial apoptosis and ferroptosis. These results might highlight promising therapeutic potential of BJTD for ovarian reserve preservation.

Screening Anti-Parkinson's Disease Drugs in Living Mouse Brains via a Peroxynitrite-Activated Fluorescent Probe

Screening anti-Parkinson's disease (PD) drugs at in vivo brain level is imperative for managing PD yet currently remains unaccomplished. Peroxynitrite (ONOO-) has been implicated in PD progression. Thus, developing in vivo ONOO--based imaging tools for anti-PD drug screening holds promise for early prognosis and treatment of PD. Consequently, a near-infrared (NIR) fluorescence probe, BOB-Cl-PN, with high specificity, good sensitivity (LOD = 24 nM), and rapid response (<60 s), was devised to investigate ONOO- and PD relationships. Utilizing NIR fluorescence imaging, BOB-Cl-PN effectively monitored ONOO- fluctuations in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD cell models, establishing a cellular high throughput screening (cHTS) system for anti-PD drugs. In live animal imaging, BOB-Cl-PN's ability to penetrate the blood-brain barrier enabled ONOO- flux imaging of PD mouse brains. Moreover, BOB-Cl-PN served as an imaging contrast for in vivo screening of potential traditional Chinese medicines for PD therapy, identifying fisetin as having the best therapeutic index among 10 Chinese medicines. This study constructs a sensitive, efficient imaging contrast for monitoring ONOO- dynamics in PD brains and provides a valuable platform for cellular and in vivo screening of anti-PD drugs.

Nanomedical Strategies for Kidney Disease: Diagnostic Innovations and Therapeutic Advancements

Kidney diseases, posing significant global public health challenges due to their complex pathogenesis and diagnostic/therapeutic difficulties, have seen emerging advancements through nanomedicine. In diagnostics, nanoparticles leverage unique physicochemical properties to enhance imaging precision. Superparamagnetic iron oxide nanoparticles improve magnetic resonance imaging sensitivity by amplifying T2-weighted contrast, while microbubbles/nanobubbles enhance ultrasound resolution via signal reflection. Quantum dots and gold nanoparticles optimize photoacoustic imaging with superior fluorescence and photostability. Therapeutically, nanoparticle-based drug delivery systems demonstrate targeted delivery, reduced systemic toxicity, and improved drug stability and bioavailability in preclinical studies. Nanocarrier-integrated stem cell and gene therapies further show potential in repairing renal cells and mitigating kidney injury. This review systematically examines nanomedicine's dual diagnostic and therapeutic roles in kidney diseases, compares strengths and limitations of various nanodelivery platforms, and addresses current challenges in clinical translation. By exploring novel nanotechnology-driven strategies, it aims to guide future research toward effective, tailored therapies for improved renal disease management.

A Kidney-Targeted Rapid Photoacoustic Probe Activated by Sulfur Dioxide for 3D Visual Diagnosis of Iodinated Contrast-Induced Acute Kidney Injury

Sulfur dioxide (SO2) dysmetabolism is closely associated with various diseases such as acute kidney injury (AKI). Nevertheless, the relationship between SO2 levels and iodinated contrast-induced AKI remains largely unclear. Therefore, accurate imaging of SO2 level fluctuations in vivo is therefore critically important. However, no photoacoustic (PA) imaging method is currently available for the detection of SO2. To address this gap, we designed and synthesized a PA probe toward SO2, namely, Rho-QL, for the first time and performed in situ PA imaging of SO2 in deep tissues in vivo. A novel method was accordingly developed for the 3D visual diagnosis of AKI based on PA imaging of SO2 in kidney tissues with high spatial resolution. Rho-QL exhibited a PA response time of 5 s for SO2 and displayed remarkable turn-on absorption changes at 700 nm, making it a suitable probe for detecting SO2 levels via PA imaging. Moreover, Rho-QL exhibited an excellent targeting ability to the kidney, thereby facilitating in situ imaging of SO2 in the kidney. Notably, through real-time PA imaging, Rho-QL was successfully applied for 3D visualization of the detailed SO2 distribution with high spatial resolution and revealed a remarkable increase in the SO2 levels in the kidney during a contrast-induced AKI process. Based on the current findings, Rho-QL is expected to become a powerful tool for the study and diagnosis of AKI-related diseases.

A Dual-Channel Fluorescence Probe for Early Diagnosis and Treatment Monitoring of Acute Kidney Injury by Detecting HOCl and Cys with Different Fluorescence Signals

The pathogenesis of acute kidney injury (AKI) is a multifaceted process involving various mechanisms, with oxidative stress playing a crucial role in its development. Hypochlorite (HOCl) and cysteine (Cys) are indicators of oxidative stress in AKI pathophysiology, directly reflecting the degree of oxidative stress and disease severity. However, their exact mechanism of action in AKI pathophysiology remains unknown. Herein, we developed a dual-channel fluorescent probe, MB-NAP, which allowed for the simultaneous detection of HOCl and Cys. The probe exhibited distinct fluorescence responses in the green channel (λex = 450 nm, λem = 560 nm) and red channel (λex = 610 nm, λem = 690 nm), without any spectral crosstalk, allowing for accurate measurement of both analytes. We successfully applied MB-NAP to monitor the levels of HOCl and Cys in cellular and in vivo models of AKI, revealing a significant increase in their concentrations compared to normal models. Furthermore, MB-NAP was demonstrated to exhibit outstanding capabilities for drug screening by effectively real-time monitoring HOCl and Cys. This study not only provides a more sensitive and reliable method/tool for tracking AKI-related pathological processes but also offers a potential breakthrough in the early diagnosis and identification of therapeutic agents aimed at mitigating oxidative stress-induced damage in AKI.

Finely Tailored Conjugated Small Molecular Nanoparticles for Near-Infrared Biomedical Applications

Near-infrared (NIR) phototheranostics (PTs) show higher tissue penetration depth, signal-to-noise ratio, and better biosafety than PTs in the ultraviolet and visible regions. However, their further advancement is severely hindered by poor performances and short-wavelength absorptions/emissions of PT agents. Among reported PT agents, conjugated small molecular nanoparticles (CSMNs) prepared from D-A-typed photoactive conjugated small molecules (CSMs) have greatly mediated this deadlock by their high photostability, distinct chemical structure, tunable absorption, intrinsic multifunctionality, and favorable biocompatibility, which endows CSMNs with more possibilities in biological applications. This review aims to introduce the recent progress of CSMNs for NIR imaging, therapy, and synergistic PTs with a comprehensive summary of their molecular structures, structure types, and optical properties. Moreover, the working principles of CSMNs are illustrated from photophysical and photochemical mechanisms and light-tissue interactions. In addition, molecular engineering and nanomodulation approaches of CSMs are discussed, with an emphasis on strategies for improving performances and extending absorption and emission wavelengths to the NIR range. Furthermore, the in vivo investigation of CSMNs is illustrated with solid examples from imaging in different scenarios, therapy in 2 modes, and synergistic PTs in combinational functionalities. This review concludes with a brief conclusion, current challenges, and future outlook of CSMNs.

Engineering of Kidney-Targeting Fluorophores with Tunable Emission from NIR-I to NIR-II for Early Diagnosis of Kidney Disease

The development of rapidly distributed and retained probes within the kidneys is important for accurately diagnosing kidney diseases. Although molecular imaging shows the potential for non-intrusively interrogating kidney disease-related biomarkers, the limited kidney contrast of many fluorophores, owing to their relatively low distribution in the kidney, hinders their effectiveness for kidney disease detection. Herein, for the first time, an amino-functionalization strategy is proposed to construct a library of kidney-targeting fluorophores NHcy with tunable emissions from NIR-I to NIR-II. Among these, NHcy-8 is the first small-molecule NIR-II dye without a renal clearance moiety, designed specifically for kidney-targeting imaging. Building on this class of NIR-II fluorophore, the first NIR-II small-molecule kidney-targeting pH probe NIR-II-pH is developed, which exhibits a desirable kidney distribution after intravenous injection and is fluorescent only after activation by acidosis. NIR-II in vivo fluorescence/photoacoustic imaging of kidney disease models induced by cisplatin and renal I/R injury using NIR-II-pH reveals increasingly severe metabolic acidosis as the disease progressed, enabling sensitive detection of the onset of acidosis 36 h (cisplatin group) earlier than clinical methods. Thus, this study introduces a practical NIR-II kidney-targeting probe and provides a useful molecular blueprint for guiding kidney-targeting NIR-II fluorophores as diagnostic aids for kidney diseases.

Fluorimetric Tool to Discriminate Glomerular and Tubular Injuries In Vivo

The etiology and pathological complexity of acute kidney injury (AKI) pose great challenges for early diagnosis, typing, and personalized treatment. It is an important reason for poor prognosis and high mortality of AKI. In order to provide a relatively noninvasive diagnostic and typing method for AKI, we proposed the pathological changes of albumin permeability after glomerular injury and reabsorption efficiency after tubular injury as potential entry points. Thus, a renal tubule labeling fluorescent dye which features albumin concentration-related fluorescence intensity was used to fit these pathological changes. Utilizing this fluorescence assay, we realized urinary tract obstruction imaging as early as 12 h after morbidity. For glomerular and tubular injury discrimination, compared to a healthy control, membranous nephropathy as a representative glomerular injury resulted in enhanced fluorescence intensity of the kidney due to increased albumin penetration, while renal tubular injury caused insufficient dye reabsorption to exhibit weakened fluorescence intensity. The significant differences demonstrated the feasibility of this approach for fluorescence imaging-based AKI typing in vivo.

Homo-Dyad with Outer Hydration Layer Approach for Developing NIR-II Chromophore of High Stability and Water-Solubility as Injectable and Sprayable Optical Probe

Dyes with extended conjugate structures are the focus of extensive design and synthesis efforts, aiming to confer unique and improved optical and electronic properties. Such advancements render these dyes applicable across a wide spectrum of uses, ranging from second-window near-infrared (NIR-II) bioimaging to organic photovoltaics. Nevertheless, the inherent benefits of long conjugation are often accompanied by persistent challenges like aggregation, fluorescence quenching, absorption blueshift, and low stability and poor water solubility. Herein, a unique structural design strategy termed "homo-dyad with outer hydration layer" is introduced to address these inherent problems, tailored for the development of imaging probes exhibiting long absorption/emission wavelengths. This approach involves bringing two heptamethine cyanines together through a flexible linker, forming a homo-dyad structure, while strategically attaching four polyethylene glycol (PEG9) chains to the terminal heterocycles. This approach imparts excellent water solubility, biocompatibility, and enhanced chemical, photo-, and spectral stability for the dyes. Utilizing this strategy, a biomarker-activatable probe (HD-FL-4PEG9-N) for NIR-II fluorescent and 3D multispectral optoacoustic tomography imaging is developed, and its effectiveness in disease visualization. It can not only serve as an injectable probe for acute kidney injury imaging due to its high water solubility, but also a sprayable probe for imaging bacterial-infected wounds.