Rhodamine-based fluorescent sensors for the rapid and selective off-on detection of salicylic acid and their use in plant cell imaging.

Salicylic acid (SA) is a key hormone that regulates plant growth and immunity, and understanding the physiologic processes induced by SA enables the development of highly pathogen-resistant crops. Here, we report the synthesis of three new SA-sensors (R1-R3) from hydroxyphenol derivatives of a rhodamine-acylhydrazone scaffold and their characterization by NMR and HRMS. Spectroscopic analyses revealed that structural variations in R1-R3 resulted in sensors with different sensitivities for SA. Sensor R2 (with the 3-hydroxyphenyl modification) outperformed R1 (2-hydroxyphenyl) and R3 (4-hydroxyphenyl). The SA-detection limit of R2 is 0.9 µM with an ultra-fast response time (<60 s). In addition, their plant imaging indicated that designed sensor R2 is useful for the further study of SA biology and the discovery and development of new inducers of plant immunity.

Xuebijing improves intestinal microcirculation dysfunction in septic rats by regulating the VEGF-A/PI3K/Akt signaling pathway.

BACKGROUND: This study aims to explore whether Xuebijing (XBJ) can improve intestinal microcirculation dysfunction in sepsis and its mechanism. METHODS: A rat model of sepsis was established by cecal ligation and puncture (CLP). A total of 30 male SD rats were divided into four groups: sham group, CLP group, XBJ + axitinib group, and XBJ group. XBJ was intraperitoneally injected 2 h before CLP. Hemodynamic data (blood pressure and heart rate) were recorded. The intestinal microcirculation data of the rats were analyzed via microcirculation imaging. Enzyme-linked immunosorbent assay (ELISA) kits were used to detect the serum levels of interleukin-6 (IL-6), C-reactive protein (CRP), and tumor necrosis factor-α (TNF-α) in the rats. Histological analysis and transmission electron microscopy were used to analyze the injury of small intestinal microvascular endothelial cells and small intestinal mucosa in rats. The expression of vascular endothelial growth factor A (VEGF-A), phosphoinositide 3-kinase (PI3K), phosphorylated PI3K (p-PI3K), protein kinase B (Akt), and phosphorylated Akt (p-Akt) in the small intestine was analyzed via Western blotting. RESULTS: XBJ improved intestinal microcirculation dysfunction in septic rats, alleviated the injury of small intestinal microvascular endothelial cells and small intestinal mucosa, and reduced the systemic inflammatory response. Moreover, XBJ upregulated the expression of VEGF-A, p-PI3K/total PI3K, and p-Akt/total Akt in the rat small intestine. CONCLUSION: XBJ may improve intestinal microcirculation dysfunction in septic rats possibly through the VEGF-A/PI3K/Akt signaling pathway.

Recent progress and outlooks in rhodamine-based fluorescent probes for detection and imaging of reactive oxygen, nitrogen, and sulfur species.

Reactive oxygen species (ROS), reactive nitrogen species (RNS), and reactive sulfur species (RSS) serve as vital mediators essential for preserving intracellular redox homeostasis within the human body, thereby possessing significant implications across physiological and pathological domains. Nevertheless, deviations from normal levels of ROS, RNS, and RSS disturb redox homeostasis, leading to detrimental consequences that compromise bodily integrity. This disruption is closely linked to the onset of various human diseases, thereby posing a substantial threat to human health and survival. Small-molecule fluorescent probes exhibit considerable potential as analytical instruments for the monitoring of ROS, RNS, and RSS due to their exceptional sensitivity and selectivity, operational simplicity, non-invasiveness, localization capabilities, and ability to facilitate in situ optical signal generation for real-time dynamic analyte monitoring. Due to their distinctive transition from their spirocyclic form (non-fluorescent) to their ring-opened form (fluorescent), along with their exceptional light stability, broad wavelength range, high fluorescence quantum yield, and high extinction coefficient, rhodamine fluorophores have been extensively employed in the development of fluorescent probes. This review primarily concentrates on the investigation of fluorescent probes utilizing rhodamine dyes for ROS, RNS, and RSS detection from the perspective of different response groups since 2016. The scope of this review encompasses the design of probe structures, elucidation of response mechanisms, and exploration of biological applications.

Understanding the AIE phenomenon of nonconjugated rhodamine derivatives via aggregation-induced molecular conformation change.

The bottom-up molecular science research paradigm has greatly propelled the advancement of materials science. However, some organic molecules can exhibit markedly different properties upon aggregation. Understanding the emergence of these properties and structure-property relationship has become a new research hotspot. In this work, by taking the unique closed-form rhodamines-based aggregation-induced emission (AIE) system as model compounds, we investigated their luminescent properties and the underlying mechanism deeply from a top-down viewpoint. Interestingly, the closed-form rhodamine-based AIE system did not display the expected emission behavior under high-viscosity or low-temperature conditions. Alternatively, we finally found that the molecular conformation change upon aggregation induced intramolecular charge transfer emission and played a significant role for the AIE phenomenon of these closed-form rhodamine derivatives. The application of these closed-form rhodamine-based AIE probe in food spoilage detection was also explored.

Corrigendum: RIPK1 in the inflammatory response and sepsis: recent advances, drug discovery and beyond.

[This corrects the article DOI: 10.3389/fimmu.2023.1114103.].

p53-Dependent ferroptosis pathways in sepsis.

Sepsis is caused by complex infections, trauma, and major surgery that results in high morbidity and mortality. As one of the leading causes of death in the intensive care unit (ICU）, sepsis causes organ dysfunction and death via a vicious cycle of uncontrolled inflammatory responses and immunosuppression. Ferroptosis is an iron-dependent cellular death pathway driven by the accumulation of lipid peroxides, which occurs in sepsis. p53 is an important regulator of ferroptosis. Under intracellular/extracellular stimulation and pressure, p53 acts as a transcription factor to regulate the expression of downstream genes, which help cells/bodies to resist stimuli. p53 can also function independently as an important mediator. The understanding of key cellular and molecular mechanisms of ferroptosis facilitates the prognosis of sepsis. This article describes the molecular mechanism and role of p53 in sepsis-induced ferroptosis, and introduces some potential therapeutic targets for sepsis-induced ferroptosis, which highlights the dominant and potential therapeutic role of p53 in sepsis. Keywords: p53, acetylation, Sirt3, ferroptosis, sepsis, therapy.

RIPK1 in the inflammatory response and sepsis: Recent advances, drug discovery and beyond.

Cytokine storms are an important mechanism of sepsis. TNF-α is an important cytokine. As a regulator of TNF superfamily receptors, RIPK1 not only serves as the basis of the scaffold structure in complex I to promote the activation of the NF-κB and MAPK pathways but also represents an important protein in complex II to promote programmed cell death. Ubiquitination of RIPK1 is an important regulatory function that determines the activation of cellular inflammatory pathways or the activation of death pathways. In this paper, we introduce the regulation of RIPK1, RIPK1 PANoptosome's role in Inflammatory and sepsis, and perspectives.

Dl-3-n-butylphthalide improves intestinal microcirculation disorders in septic rats by regulating the PI3K/AKT signaling pathway and autophagy.

PURPOSE: Sepsis has complex pathophysiological mechanisms that bring new challenges in the treatment of sepsis at a time when the intestinal microcirculation in sepsis is receiving increasing attention. Dl-3-n-butylphthalide (NBP), which is a drug that can improve multiorgan ischemic diseases, is also worth examining to improve the intestinal microcirculation in sepsis. METHODS: In this study, male Sprague-Dawley rats were divided into the sham group (n = 6), CLP group (n = 6), NBP group (n = 6) and NBP + LY294002 group (n = 6). The rat model of severe sepsis was established by cecal ligation and puncture (CLP). Abdominal wall incisions and sutures were performed in the first group, and CLP was performed in the latter three groups. Normal saline/NBP/NBP + LY294002 solution was injected intraperitoneally 2 h or 1 h before modeling. Hemodynamic data (blood pressure and heart rate) were recorded at 0, 2, 4 and 6 h. Sidestream dark field (SDF) imaging and the Medsoft System were used to observe the intestinal microcirculation of rats and obtain data at 0, 2, 4, and 6 h. Six hours after the model was established, the serum levels of TNF-α and IL-6 were measured to evaluate the level of systemic inflammation. Pathological damage to the small intestine was evaluated by electron microscopy and histological analysis. The expression levels of P-PI3K, PI3K, P-AKT, AKT, LC3 and p62 in the small intestine were analyzed by Western blotting. The expressions of P-PI3K, P-AKT, LC3 and P62 in small intestine were detected by immunohistochemical staining. RESULTS: NBP improved intestinal microcirculation disturbances in septic rats, alleviated the systemic inflammatory response, reduced the destruction of the small intestinal mucosa and the disruption of microvascular endothelial cells, and alleviated autophagy in vascular endothelial cells. NBP increased the ratio of P-PI3K/total PI3K, P-AKT/total AKT, and P62/ß-actin and decreased the ratio of LC3 II/LC3 I. CONCLUSION: NBP ameliorated intestinal microcirculation disturbances and the destruction of small intestinal vascular endothelial cells in septic rats by activating the PI3K/Akt signaling pathway and regulating autophagy.

Highly Selective and Rapid "Turn-On" Fluorogenic Chemosensor for Detection of Salicylic Acid in Plants and Food Samples.

Salicylic acid (SA) is one of the chemical molecules, involved in plant growth and immunity, thereby contributing to the control of pests and pathogens, and even applied in fruit and vegetable preservation. However, only a few tools have ever been designed or executed to understand the physiological processes induced by SA or its function in plant immunity and residue detection in food. Hence, three Rh6G-based fluorogenic chemosensors were synthesized to detect phytohormone SA based on the "OFF-ON" mechanism. The probes showed high selectivity, ultrafast response time (<60 s), and nanomolar detection limit for SA. Moreover, the probe possessed outstanding profiling that can be successfully used for SA imaging of callus and plants. Furthermore, the fluorescence pattern indicated that SA could occur in the distal transport in plants. These remarkable results contribute to improving our understanding of the multiple physiological and pathological processes involved in SA for plant disease diagnosis and for the development of immune activators. In addition, SA detection in some agricultural products used probes to extend the practical application because its use is prohibited in some countries and is harmful to SA-sensitized persons. Interestingly, the as-obtained test paper displayed that SA could be imaged by ultraviolet (UV) and was directly visible to the naked eye. Given the above outcomes, these probes could be used to monitor SA in vitro and in vivo, including, but not limited to, plant biology, food residue detection, and sewage detection.

Intestinal microcirculation dysfunction in sepsis: pathophysiology, clinical monitoring, and therapeutic interventions.

BACKGROUND: Intestinal microcirculation dysfunction is an important factor that causes poor prognosis in sepsis patients and is an important pathophysiological basis for the occurrence and development of sepsis. DATA RESOURCES: PubMed, Web of Science, and China National Knowledge Infrastructure (CNKI) were searched from inception to August 1, 2021. The search was limited to the English language only. Two reviewers independently identified studies related to intestinal microcirculation dysfunction in sepsis. Exclusion criteria were duplicate articles according to multiple search criteria. RESULTS: Fifty articles were included, and most of them were animal studies. These studies reported pathogenesis, including endothelial dysfunction, leukocyte recruitment and adhesion, microthrombus formation, microcirculation hypoperfusion, and redistribution of intestinal wall blood flow. The monitoring methods of intestinal microcirculation were also diverse, including handheld microscopes, intravital microscopy (IVM), laser Doppler blood flow instruments, laser speckle contrast imaging, tissue reflectance spectrophotometry, biochemical markers of intestinal ischemia, and histopathological examination. In view of the related pathogenesis of intestinal microcirculation disorder in sepsis, existing studies also have different opinions on its treatment. CONCLUSIONS: Limited by monitoring, there are few clinical studies on intestinal microcirculation dysfunction in sepsis. Related research mainly focuses on basic research, but some progress has also been made. Therefore, this review may provide a reference for future research on intestinal microcirculation dysfunction in sepsis.

Trichostatin A improves the inflammatory response and liver injury in septic mice through the FoxO3a/autophagy signaling pathway.

BACKGROUND: Sepsis-induced liver injury is a fatal complication of sepsis. Trichostatin A (TSA) regulates inflammation and autophagy in some human diseases, and forkhead box O3a (FoxO3a) has been shown to regulate autophagy. The present study aims to investigate whether TSA exerts its effects on septic liver injury through the FoxO3a/autophagy signaling pathway. METHODS: A sepsis mouse model was constructed by the cecal ligation and puncture (CLP) method, and AML12 cells were pretreated with lipopolysaccharide (LPS) (1 µg/mL) to establish a sepsis cell model. Forty mice were divided into four groups, namely control group, TSA group, CLP group, and CLP+TSA group, with 10 mice in each group. Cells were divided into control group, TSA group, LPS group, and LPS+TSA group. Hematoxylin-eosin (H&E) staining and biochemical methods were used to evaluate liver tissue injury. Enzyme-linked immunosorbent assay (ELISA) was applied to detect the expression of proinflammatory cytokines, and Western blotting and immunofluorescence were used to measure autophagy-related protein expression. RESULTS: Compared with the CLP group (mice), the proinflammatory cytokines (interleukin-ß [IL-ß] 2,665.27±324.90 pg/mL to 2,080.26±373.66 pg/mL; interleukin-6 [IL-6] 399.01±60.98 pg/mL to 221.90±46.89 pg/mL) and the hepatocyte injury markers (aspartate transaminase [AST] from 198.18±27.07 U/L to 128.42±20.55 U/L; alanine aminotransferase [ALT] from 634.98±74.10 U/L to 478.60±32.56 U/L) were notably decreased after TSA intervention. Moreover, LC3 II and FoxO3a showed an obvious increase and P62 showed an obvious decrease in the CLP+TSA group. Cell experiment results showed the similar trend. After FoxO3a gene was knocked down in AML12 cells, the promotion of autophagy and the improvement of liver enzyme index and inflammation by TSA were weakened. CONCLUSION: TSA may improve the inflammatory response and liver injury in septic mice through FoxO3a/autophagy.

Prognostic role of elevated VEGF in sepsis: A systematic review and meta-analysis.

Background: The incidence and mortality of sepsis are increasing year by year, and there is still a lack of specific biomarkers to predict its prognosis. Prognostic value of vascular endothelial growth factor (VEGF) in predicting the severity and mortality of sepsis has been gradually discovered. Methods: Literature was searched through Embase, PubMed, Web of Science, China National Knowledge Infrastructure(CNKI) and Cochrane Library databases in March 2022. Observational studies, evaluating the impact of VEGF in sepsis outcomes (mortality and severity) are included in this meta-analysis. Risk of bias was assessed with the Newcastle-Ottawa Scale (NOS). Sensitivity and publication bias analyses were also assessed. Meta-regression analysis were performed to identify the potential sources of heterogeneity. Result: A total of 1,574 articles were retrieved from the systematic literature search. We included 20 studies for qualitative and quantitative analysis. Deceased and critically ill patients had higher baseline VEGF levels than survivors and non-severe patients. The pooled sensitivity and specificity for VEGF predicts sepsis mortality were 0.79and 0.76, respectively. the area under the SROC curve was 0.83. Conclusion: High VEGF are associated with poor clinical outcomes for patients diagnosed with sepsis. This study was recorded on PROSPERO, under the registration ID: CRD42022323079.

Sirt3 Maintains Microvascular Endothelial Adherens Junction Integrity to Alleviate Sepsis-Induced Lung Inflammation by Modulating the Interaction of VE-Cadherin and ß-Catenin.

Inflammatory injury is a hallmark of sepsis-induced acute respiratory distress syndrome (ARDS)/acute lung injury (ALI). However, the mechanisms underlying inflammatory injury remain obscure. Here, we developed the novel strategy to suppress lung inflammation through maintaining microvascular endothelial barrier integrity. VE-cadherin is the main adherens junction protein that interacts with ß-catenin and forms a complex. We found that lung inflammation was accompanied by decreased VE-cadherin expression and increased ß-catenin activity in animal models and human pulmonary microvascular endothelial cells (HPMECs), illuminating the relationship among VE-cadherin/ß-catenin complex, microvascular endothelial barrier integrity, and inflammation. Furthermore, we showed that the VE-cadherin/ß-catenin complex dissociated upon lung inflammation, while Sirt3 promoted the stability of such a complex. Sirt3 was decreased during lung inflammation in vivo and in vitro. Sirt3 deficiency not only led to the downregulation of VE-cadherin but also enhanced the transcriptional activity of ß-catenin that further increased ß-catenin target gene MMP-7 expression, thereby promoting inflammatory factor COX-2 expression. Sirt3 overexpression promoted VE-cadherin expression, inhibited ß-catenin transcriptional activity, strengthened the stability of the VE-cadherin/ß-catenin complex, and suppressed inflammation in HPMECs. Notably, Sirt3 deficiency significantly damaged microvascular endothelial barrier integrity and intensified lung inflammation in animal model. These results demonstrated the role of Sirt3 in modulating microvascular endothelial barrier integrity to inhibit inflammation. Therefore, strategies that aim at enhancing the stability of endothelial VE-cadherin/ß-catenin complex are potentially beneficial for preventing sepsis-induced lung inflammation.

Switching of C-C and C-N Coupling/Cleavage for Hypersensitive Detection of Cu2+ by a Catalytically Mediated 2-Aminoimidazolyl-Tailored Six-Membered Rhodamine Probe.

A robust six-membered rhodamine spirocyclic probe 1 containing a versatile 2-aminoimidazolyl moiety was elaborately designed and synthesized via an attractive C-C and C-N coupling strategy to improve the performance in the detection of ultralow transition metal ions. Probe 1 allowed the highly hypersensitive detection of Cu2+ with a superior picomolar limit of detection (35 pM) and nanomolar naked-eye performance (80 nM) via the switching of C-C and C-N cleavage by a catalytic hydrolysis mode.

Curcumin-Cu(II) Ensemble-Based Fluorescence "Turn-On" Mode Sensing the Plant Defensive Hormone Salicylic Acid In Situ and In Vivo.

Salicylic acid (SA), a crucial, plant-derived signal molecule, is capable of launching global transcriptional reprogramming to assist plants in obtaining the systemic acquired resistance (SAR) mechanism. Thus, the accurate detection of SA will not only significantly contribute to the understanding of the plant SAR but also contribute to crop protection and to the security of the agricultural production and food supply. However, detection of SA using fluorescent probes is a great challenge for scientists, because SA analogues can significantly interfere with the detection results. Herein, we first reported using a simple, natural curcumin-Cu2+ ensemble to selectively and sensitively monitor SA in situ and in vivo, directed by a fluorescence "turn-on" mode. A binary combination curcumin-Cu2+ was first fabricated with a fluorescence "turn-off" pattern caused by the paramagnetic nature of Cu2+. Subsequently, a fluorescence "turn-on" response was performed for detecting SA accompanied by the formation of the ternary complex curcumin-Cu2+-SA due to the high affinity of SA toward Cu2+, which reduced the fluorescent impact caused by the paramagnetism of Cu2+. Further study revealed that the rationally designed hybrid probe could monitor SA in living cell lines. We anticipate that this finding can inspire the discovery of a high-performance SA probe.