ObjectiveThis study aims to investigate whether Xixintang could ameliorate cognitive dysfunction in an Alzheimer's disease （AD） rat model induced by D-galactose and β-amyloid （Aβ_25-35）， by means of repairing the colonic mucosal barrier， regulating the Toll-like receptor 4 （TLR4）/nuclear factor-κB p65 （NF-κB p65） signaling pathway， and intervening in the pathological process mediated by the gut-brain axis. MethodsSixty specific pathogen-free （SPF） male Sprague-Dawley （SD） rats were randomly divided to five groups （n=12）： A control group， a model group， a donepezil group， an Xixintang group， and a probiotic group. Except for those in the control group， rats in all other groups received daily intraperitoneal injections of D-galactose for six consecutive weeks. Subsequently， aggregated Aβ_25-35 was injected stereotactically into the bilateral ventricles to establish the AD model. During the intervention periods， the rats in all groups were administered their respective drugs and normal saline by gavage. The Morris water maze test was used to assess the capacity for spatial learning and memory. Hematoxylin-eosin （HE） staining was employed to observe the histopathological changes in the colon tissues. Immunofluorescence was used to detect Aβ_1-41 deposition in the hippocampal region and Mucin 2 （MUC2） expression in the colonic mucosa. Western blot was performed to measure the protein expression levels of FFAR2，TLR4， NF-κB p65， occludin （OCLN）， zonula occludens-1 （ZO-1）， and MUC2 in the colonic tissues. Enzyme-linked immunosorbent assay （ELISA） was used to determine the contents of interleukin-6 （IL-6）， tumor necrosis factor-α （TNF-α）， serum amyloid A （SAA）， and Aβ_1-42 in the hippocampal region from the colonic tissues. The lipopolysaccharide （LPS） concentrations in colon tissues of rats were measured by using a dynamic chromogenic limulus assay. ResultsCompared with those in the control group， the rats in the model group exhibited a significantly prolonged escape latency and a markedly shorter duration in the target quadrant （P<0.01）. The integrity of the colonic mucosal structure was compromised， with disordered gland arrangement and a reduced number of goblet cells. The Aβ_1-42 deposition in the hippocampal region was significantly increased （P<0.01）. The protein expression levels of TLR4 and NF-κB p65 in colonic tissues were significantly upregulated （P<0.01）， while those of occludin and ZO-1 were downregulated （P<0.01）. The contents of inflammatory factors such as IL-6， TNF-α， and SAA were significantly elevated （P<0.01）， and the LPS level in the serum was markedly increased （P<0.01）. In comparison to those in the model group， the rats in the Xixintang group showed a significantly shortened escape latency and a prolonged duration in the target quadrant （P<0.01）. The colonic mucosal structure was ameliorated， with neat gland arrangement and an increased number of goblet cells. The Aβ_1-42 deposition in the hippocampal region was reduced （P<0.01）. The protein expressions of TLR4 and NF-κB p65 in the colon tissues were decreased （P<0.05，P<0.01）， while the protein levels of occludin and ZO-1 were increased （P<0.01）. The contents of IL-6， TNF-α， and serum amyloid A （SAA） were decreased （P<0.01）， and the LPS level was reduced （P<0.01）. ConclusionXixintang can significantly ameliorate cognitive dysfunction of AD model rats， by means of restoring the colonic mucosal barrier structure， reducing cerebral Aβ deposition， and suppressing peripheral and central inflammatory response. Its mechanism of action may be closely associated with the suppression of the TLR4/NF-κB signaling pathway activation， reduction of endotoxin levels， and regulation of the gut-brain axis.

ObjectiveThis study aims to investigate whether Xixintang could ameliorate cognitive dysfunction in an Alzheimer's disease （AD） rat model induced by D-galactose and β-amyloid （Aβ_25-35）， by means of repairing the colonic mucosal barrier， regulating the Toll-like receptor 4 （TLR4）/nuclear factor-κB p65 （NF-κB p65） signaling pathway， and intervening in the pathological process mediated by the gut-brain axis. MethodsSixty specific pathogen-free （SPF） male Sprague-Dawley （SD） rats were randomly divided to five groups （n=12）： A control group， a model group， a donepezil group， an Xixintang group， and a probiotic group. Except for those in the control group， rats in all other groups received daily intraperitoneal injections of D-galactose for six consecutive weeks. Subsequently， aggregated Aβ_25-35 was injected stereotactically into the bilateral ventricles to establish the AD model. During the intervention periods， the rats in all groups were administered their respective drugs and normal saline by gavage. The Morris water maze test was used to assess the capacity for spatial learning and memory. Hematoxylin-eosin （HE） staining was employed to observe the histopathological changes in the colon tissues. Immunofluorescence was used to detect Aβ_1-41 deposition in the hippocampal region and Mucin 2 （MUC2） expression in the colonic mucosa. Western blot was performed to measure the protein expression levels of FFAR2，TLR4， NF-κB p65， occludin （OCLN）， zonula occludens-1 （ZO-1）， and MUC2 in the colonic tissues. Enzyme-linked immunosorbent assay （ELISA） was used to determine the contents of interleukin-6 （IL-6）， tumor necrosis factor-α （TNF-α）， serum amyloid A （SAA）， and Aβ_1-42 in the hippocampal region from the colonic tissues. The lipopolysaccharide （LPS） concentrations in colon tissues of rats were measured by using a dynamic chromogenic limulus assay. ResultsCompared with those in the control group， the rats in the model group exhibited a significantly prolonged escape latency and a markedly shorter duration in the target quadrant （P<0.01）. The integrity of the colonic mucosal structure was compromised， with disordered gland arrangement and a reduced number of goblet cells. The Aβ_1-42 deposition in the hippocampal region was significantly increased （P<0.01）. The protein expression levels of TLR4 and NF-κB p65 in colonic tissues were significantly upregulated （P<0.01）， while those of occludin and ZO-1 were downregulated （P<0.01）. The contents of inflammatory factors such as IL-6， TNF-α， and SAA were significantly elevated （P<0.01）， and the LPS level in the serum was markedly increased （P<0.01）. In comparison to those in the model group， the rats in the Xixintang group showed a significantly shortened escape latency and a prolonged duration in the target quadrant （P<0.01）. The colonic mucosal structure was ameliorated， with neat gland arrangement and an increased number of goblet cells. The Aβ_1-42 deposition in the hippocampal region was reduced （P<0.01）. The protein expressions of TLR4 and NF-κB p65 in the colon tissues were decreased （P<0.05，P<0.01）， while the protein levels of occludin and ZO-1 were increased （P<0.01）. The contents of IL-6， TNF-α， and serum amyloid A （SAA） were decreased （P<0.01）， and the LPS level was reduced （P<0.01）. ConclusionXixintang can significantly ameliorate cognitive dysfunction of AD model rats， by means of restoring the colonic mucosal barrier structure， reducing cerebral Aβ deposition， and suppressing peripheral and central inflammatory response. Its mechanism of action may be closely associated with the suppression of the TLR4/NF-κB signaling pathway activation， reduction of endotoxin levels， and regulation of the gut-brain axis.

ObjectiveZheng’s San Qi San (ZSQS) power, a classic traditional Chinese medicine (TCM) formula, is used for treating soft tissue injuries involving muscles, tendons, and ligaments. However, its underlying therapeutic mechanisms remain unclear. This study aimed to screen and identify pharmaceutically active ingredients and their candidate biomolecule targets, and further elucidate the molecular mechanism of ZSQS in the treatment of skeletal muscle injury. MethodsNetwork pharmacology was employed to construct “ZSQS-component-target”, “protein-protein interaction (PPI)” and “active ingredient-core protein-pathway” networks to predict the key active ingredients and potential core targets of ZSQS for skeletal muscle injury. The predicted results were then validated via microarray data from the GEO database. Molecular docking was then performed to assess the binding ability between the screened active ingredients of ZSQS and the candidate core targets. Moreover, liquid chromatography-mass spectrometry (LC-MS) was used for qualitative and quantitative analysis to verify the active components of the drug and ZSQS serum. Finally, an animal model of eccentric exercise-induced skeletal muscle injury and a myotube cell model of oxidative stress-induced injury were established to validate the effects of ZSQS and its interventional effects on the biological functions of critical targets, thereby demonstrating the potential therapeutic mechanism of ZSQS. ResultsAmong the 111 active components identified in ZSQS and their corresponding 204 targets related to the skeletal muscle injury repair process, 14 core targets (including AKT1) and 4 core active components (quercetin, luteolin, kaempferol, and β‑sitosterol) were screened out, while the corresponding metabolites of quercetin, luteolin and kaempferol were detected in the ZSQS serum. Among these targets, 5 candidate genes (IL-6, CASP3, HIF1A, STAT3, and JUN) overlapped with the differential expression screening results with GEO data, and IL-6 was confirmed to be enriched in the PI3K/AKT pathway. Combined with the prediction results of the AKT expression levels, these findings suggest that the phosphorylation level of AKT1 plays a core role in the therapeutic mechanism of ZSQS. Molecular docking analysis further revealed that the PH domain of AKT1 had high binding energy with all 4 core active components, as verified by LC-MS. Finally, animal model studies have shown the promoting effect of ZSQS administration on skeletal muscle injury repair and its possible antioxidant damage mechanism. Cell model studies further demonstrated that ZSQS-containing serum, core active ingredient combination therapy, and quercetin monomer could increase the phosphorylation level of AKT, promote the nuclear translocation of Nrf2, upregulate the expression of downstream antioxidant enzymes (SOD, GPx, and GR), and inhibit the expression of inflammatory factors (IL-6 and TNF-α), thereby alleviating oxidative stress and the inflammatory response. ConclusionZSQS alleviates skeletal muscle injury mainly by activating the AKT/Nrf2 signaling pathway, enhancing cellular antioxidant and anti-inflammatory capabilities. The results of this study provide a scientific basis for the clinical application and modernized development of ZSQS.

ObjectiveDonkey hide is the sole legally designated raw material for the preparation of the traditional Chinese medicine Ejiao. The quality stability of donkey hide during preservation directly determines the efficacy and safety of Ejiao. This study focuses on the dynamic succession of microbial communities during the preservation of donkey hides from different origins, aiming to clarify the correlation between microbial biodiversity difference and the degradation profiles of hide collagen and critical biochemical components, thereby providing a theoretical foundation for developing targeted preservation strategies based on microbial regulation. MethodsDonkey hides originating from four different regions were subjected to an accelerated microbial aging assay to simulate the spoilage process. The microbial community succession was analyzed using high-throughput sequencing. Microstructure changes and pore structure characteristics were assessed by scanning electron microscopy and mercury intrusion porosimetry, respectively. Additionally, the content of major components, including lipids, proteins, and sugars were determined by biochemical methods. ResultsAfter 96 h of aging, the collagen fiber structure in Africa donkey hides (ADH) exhibited significant degradation and collapse, followed by Xinjiang donkey hides (XDH). Instead, the microstructure of Dong’e black donkey hides (DDH) and Peru donkey hides (PDH) remained relatively intact. The porosities of DDH, XDH, PDH, and ADH increased from 27.9%, 15.7%, 30.3%, and 46.2% to 36.5%, 52.6%, 42.8%, and 57.7%, respectively, during the aging process, which suggested that the originally compact fiber structure was disrupted by microbial aging. Fourier transform infrared spectrometer analysis revealed the amide bands in XDH exhibited relatively weak intensity, and no collagen amide I band was observed in ADH. Meanwhile, the lipid and protein contents decreased in all four types of donkey hides, indicating that these components served as the primary nutrient sources for the growth of microorganism. Notably, the most severe collagen degradation was observed in XDH and ADH. A substantial increase was detected in the total soluble sugar in PDH aging solution and hydroxyproline in the ADH aging solution, respectively. These results indicated that donkey hides exhibit distinct patterns of structural degradation and nutrient utilization. Furthermore, the viable cells number of donkey hides increased sharply after 48 h of aging. Metagenomic analysis revealed that the relative abundance of Euryarchaeota in ADH, PDH and XDH declining from initial 93.19%, 97.73% and 30.08% to 0.79%, 1.43% and 0.02% after 96 h, respectively. Conversely, a significantly increase was observed in the abundance of Bacillota, with a marked increase in ADH, peaking at 92.75%. Additionally, the abundance of Pseudomonadota in PDH increased from 0.10% to 87.84%, suggesting that Bacillota and Pseudomonadota may be key factors exacerbating donkey hide spoilage. Unlike the other three types of donkey hides, the dominant bacterial phylum in DDH shifted from Pseudomonadota to Bacteroidota, characterized by a substantial abundance increase of Bacteroidota from 0.13% to 44.22%. ConclusionRegional variation in origin significantly influence the microbial aging of donkey hides, leading to distinct patterns of structural deterioration and differential nutrient utilization. Therefore, implementing origin-specific preservation strategies, through the precisely controlling environmental factors to suppress harmful phyla such as Bacillota and Pseudomonadota, is crucial for enhancing the storage quality of donkey hides.

ObjectiveThis paper aims to investigate the effects of Xixintang on aquaporin-4 （AQP4） polarity distribution， blood-brain barrier （BBB） function， and neuroinflammationin rats with Alzheimer's disease （AD）， thereby revealing the potential mechanism through which this formula protects the BBB by regulating AQP4 polarization. The aim is to provide a scientific basis for clinical treatment. MethodsSixty Sprague-Dawley （SD） rats were randomly divided into a normal group， a model group， a probiotic group， a donepezil group， and an Xixintang group. The model was established by intraperitoneal injection of D-galactose （D-Gal） combined with bilateral intracerebroventricular injection of amyloid-β_25-35 （Aβ_25-35）. The probiotic group （30.85 mg·kg^-1）， donepezil group （0.88 mg·kg^-1）， and Xixintang group （1.174 g·kg^-1） received daily gavage administration， while the normal and model groups received intragastric administration with an equal volume of normal saline for one month. Cognitive ability was assessed by using the Morris water maze. BBB permeability was detected via Evans blue extravasation. The contents of interleukin-6 （IL-6）， amyloid-β_1-42 （Aβ_1-42）， and tumor necrosis factor-α （TNF-α） in the hippocampal tissues were measured by enzyme-linked immunosorbent assay （ELISA）. The protein expressions of zonula occludens-1 （ZO-1）， occludin， tissue inhibitor of metalloproteinase-1 （TIMP-1）， matrix metalloproteinase-9 （MMP-9）， and AQP4 in the hippocampal tissues were detected by western blot. The expression and co-localization levels of Aβ_1-42， ionized calcium-binding adapter molecule 1 （IBA1）， and AQP4/platelet endothelial cell adhesion molecule 31 （CD31） in the hippocampal region were examined by immunofluorescence. ResultsCompared with the normal group， the model group exhibited a significant decline in cognitive ability （P<0.01） and a marked increase in Evans blue extravasation in the brain （P<0.01）. The expressions of ZO-1， occludin， and TIMP-1 were significantly decreased （P<0.01）， while the expressions of AQP4 and MMP-9 were significantly increased （P<0.01）. The co-localization level of AQP4/CD31 was significantly reduced （P<0.01）， and the expressions of Aβ_1-42， IL-6， TNF-α， and IBA1 were significantly elevated （P<0.01）. Compared with the model group， the Xixintang group showed significant improvement in cognitive ability （P<0.01） and a significant reduction in Evans blue extravasation in the brain （P<0.01）. The expressions of occludin， TIMP-1， and ZO-1 were significantly increased （P<0.05， P<0.01）， while the expressions of AQP4 and MMP-9 were significantly decreased （P<0.05）. The co-localization level of AQP4/CD31 was significantly enhanced （P<0.01）， and the expressions of Aβ_1-42， IL-6， TNF-α， and IBA1 were significantly reduced （P<0.05， P<0.01）. ConclusionXixintang may improve cognitive function and alleviate AD pathology in AD model rats by regulating AQP4 polarity distribution， thereby breaking the vicious cycle of "Aβ deposition-neuroinflammation-BBB damage" and restoring the homeostasis of the microenvironment in the brain.

Based on the theory of "disease of both blood and water" in Essentials from the Golden Cabinet （《金匮要略》）， and in combination with the dynamic syndrome evolution of heart failure with preserved ejection fraction （HFpEF）， this paper systematically clarifies the pathomechanism of HFpEF， characterized by yang deficiency as the root， blood stasis as the pivotal factor and water retention as the manifestation. Accordingly， the therapeutic principles have been proposed， which are warming yang and banking up original qi to consolidate the root， activating blood and unblocking collaterals to smooth the mechanism， and promoting urination and regulating pivot to remove the branch. On this basis， a compound formula structure of "one monarch， one minister and one assistant" is established， forming an integrated intervention strategy that synergistically combines the three methods of warming yang， activating blood， and promoting urination through combined classical formulas. Zhenwu Decoction （真武汤）， which warms yang and dissolves rheum， is used to consolidate the root and directly target the source of yang deficiency， serving as the monarch； Guizhi Fuling Pills （桂枝茯苓丸）， which activates blood， promotes urination and unblocks the pivot， assists in interrupting the binding of blood stasis and water retention， serving as the minister； Tingli Dazao Xiefei Decoction （葶苈大枣泻肺汤）， which regulates qi， disperses retained fluids， and eliminates the manifestation， alleviates acute water-retention symptoms， serving as the assistant. This compound formula is warming without being drying， diuretic without being drastic， and dispels stasis without consuming blood， thereby achieving the therapeutic effects of warming yang， activating blood， and promoting urination.

ObjectiveTo investigate the mechanism of Xiezhuo Jiedu prescription in the treatment of ulcerative colitis （UC） by inhibiting ferroptosis and alleviating intestinal mucosal injury based on the nuclear factor E₂ related factor 2/solute carrier family 7 member/glutathione peroxidase 4 （Nrf2/SLC7A11/GPX4） signaling pathway. MethodsA total of 60 male SD rats were divided into a normal group， a model group， high- and low-dose Xiezhuo Jiedu prescription groups （26.64 and 13.32 g·kg^-1， respectively）， a ferroptosis inhibitor group （Ferrostatin-1， 0.005 g·kg^-1）， and a mesalazine group （0.27 g·kg^-1）， with 10 rats in each group. A UC rat model was established by intrarectal administration of trinitrobenzene sulfonic acid （TNBS）-ethanol. The normal group and the model group were intragastrically administered normal saline. The other groups were given intragastric administration according to the corresponding dosage for 7 d. The general condition， disease activity index （DAI） score， colon length， and mucosal injury index （CDMI） score were observed in each group. The pathological changes of colon tissue in each group were observed by hematoxylin-eosin （HE） staining. The intestinal mucosa and mitochondrial morphology in each group were observed by transmission electron microscopy. The expression levels of Occludin， Claudin-1， mucin 2 （MUC2）， and E-cadherin in intestinal tissue were detected by immunofluorescence （IF）. Enzyme-linked immunosorbent assay （ELISA） was used to detect the expression levels of serum tumor necrosis factor-α （TNF-α）， interleukin-6 （IL-6）， and interleukin-10 （IL-10） in each group， and a lactic acid assay kit or ELISA was employed to detect the expression levels of reactive oxygen species （ROS）， ferrous ions （Fe²⁺）， glutathione （GSH）， malondialdehyde （MDA）， 4-hydroxynonenal （4-HNE）， diamine oxidase （DAO）， and D-lactate （D-LA）. Real-time quantitative polymerase chain reaction （Real-time PCR） was applied to detect the mRNA expression levels of Nrf2， SLC7A11， GPX4， Occludin， Claudin-1， MUC2， and E-cadherin in each group， and Western blot was adopted to detect the protein expression levels of Nrf2， p-Nrf2， SLC7A11， and GPX4 in each group. ResultsCompared with the normal group， rats in the model group exhibited listlessness， sluggish response， and mucopurulent and bloody stools. The model group also showed significantly increased DAI score， colon length， CDMI score， and expression levels of TNF-α， IL-6， ROS， Fe²⁺， MDA， 4-HNE， DAO， and D-LA （P<0.01）. In addition， it presented significantly decreased IF values of Occludin， Claudin-1， MUC2， and E-cadherin and mRNA and protein expression levels of IL-10， GSH， Nrf2， p-Nrf2， SLC7A11， and GPX4 （P<0.01）. There were different degrees of improvement in each administration group after treatment， and the improvement was the most significant in the high-dose Xiezhuo Jiedu prescription group （P<0.01）. ConclusionXiezhuo Jiedu prescription may alleviate intestinal mucosal injury by inhibiting ferroptosis of intestinal epithelial cells via regulating the Nrf2/SLC7A11/GPX4 signaling pathway， thereby exhibiting efficacy in the treatment of UC.

Cyclic GMP-AMP synthase (cGAS), a pivotal molecule in innate immunity, has emerged as a keypoint in interdisciplinary research at the intersection of basic immunology and tumor biology. As a cytosolic nucleic acid sensor, cGAS is primarily characterized by its capacity to recognize double-stranded DNA (dsDNA) in the cytosol. Upon binding to dsDNA, cGAS undergoes a conformational change that promotes its dimerization and subsequent enzymatic activation. Once activated, it catalyzes the synthesis of the second messenger 2',3'-cGAMP from ATP and GTP. cGAMP then binds to the adaptor protein STING, which resides on the endoplasmic reticulum (ER) membrane. The binding process triggers STING to traffic from the ER to the Golgi apparatus, where it is phosphorylated by the kinase TBK1. Phosphorylated STING serves as a docking site for the transcription factor IRF3, facilitating its phosphorylation by TBK1. Once phosphorylated, IRF3 forms dimers and translocates to the nucleus, where it drives the expression of type I interferons and pro-inflammatory cytokines, initiating a potent antimicrobial state. The DNA-sensing mechanism of cGAS is inherently non-selective regarding the origin of its ligand. It readily detects exogenous DNA from invading pathogens, thereby playing an indispensable role in host defense against microbial infections. However, this same mechanism also enables cGAS to recognize self-DNA that leaks from the nucleus or mitochondria into the cytosol under various cellular stress conditions. While critical for immunity, the recognition of self-dsDNA by cGAS can disrupt cellular homeostasis and trigger aberrant inflammatory responses. The loss of self-tolerance can precipitate or exacerbate the pathogenesis of autoimmune disorders such as systemic lupus erythematosus (SLE) and Aicardi-Goutières syndrome (AGS), highlighting the dual role of cGAS as both a sentinel for infection and a potential driver of autoimmune pathology. Notably, the subcellular localization of cGAS is not still. Increasing recent researches have revealed that cGAS is also abundant within the nucleus, challenging the traditional view of it solely as a cytosolic nucleic acid sensor. Within the nucleus, cGAS exhibits non-canonical functions that are distinct from its canonical immunological role. First, cGAS exists in a state of stringent immunological silence in the nucleus, with mechanisms involving its competitive binding to histones and its post-translational modifications which block the activation of cGAS enzymatic activity, thus, effectively preventing it from mounting an autoimmune attack on genomic DNA. Second, cGAS plays a critical role in maintaining genomic stability. Upon DNA damage, cGAS is rapidly recruited to the lesion site and participates in the DNA damage repair process. Moreover, under conditions of DNA replication stress, cGAS contributes to the stabilization of replication forks, preventing the cell from entering a state of uncontrolled hyper-replication. Consequently, in light of the dual role of cGAS in both immune regulation and tumor development, the development of small-molecule drugs targeting cGAS holds significant therapeutic promise. This review summarizes the structural characteristics of cGAS and its canonical function as a pattern recognition receptor in the cytosol, including the types of pathogens it recognizes and the autoimmune responses resulting from erroneous recognition of self-DNA. It then focuses on its emerging non-canonical functions within the nucleus, detailing its nucleocytoplasmic shuttling, the mechanisms underlying its nuclear immune quiescence, and its role in mediating DNA damage repair and replication fork stabilization. Finally, the review discusses the progress and application prospects of small-molecule drugs targeting cGAS for the treatment of autoimmune diseases and cancer.

Cyclic GMP-AMP synthase (cGAS), a pivotal molecule in innate immunity, has emerged as a keypoint in interdisciplinary research at the intersection of basic immunology and tumor biology. As a cytosolic nucleic acid sensor, cGAS is primarily characterized by its capacity to recognize double-stranded DNA (dsDNA) in the cytosol. Upon binding to dsDNA, cGAS undergoes a conformational change that promotes its dimerization and subsequent enzymatic activation. Once activated, it catalyzes the synthesis of the second messenger 2',3'-cGAMP from ATP and GTP. cGAMP then binds to the adaptor protein STING, which resides on the endoplasmic reticulum (ER) membrane. The binding process triggers STING to traffic from the ER to the Golgi apparatus, where it is phosphorylated by the kinase TBK1. Phosphorylated STING serves as a docking site for the transcription factor IRF3, facilitating its phosphorylation by TBK1. Once phosphorylated, IRF3 forms dimers and translocates to the nucleus, where it drives the expression of type I interferons and pro-inflammatory cytokines, initiating a potent antimicrobial state. The DNA-sensing mechanism of cGAS is inherently non-selective regarding the origin of its ligand. It readily detects exogenous DNA from invading pathogens, thereby playing an indispensable role in host defense against microbial infections. However, this same mechanism also enables cGAS to recognize self-DNA that leaks from the nucleus or mitochondria into the cytosol under various cellular stress conditions. While critical for immunity, the recognition of self-dsDNA by cGAS can disrupt cellular homeostasis and trigger aberrant inflammatory responses. The loss of self-tolerance can precipitate or exacerbate the pathogenesis of autoimmune disorders such as systemic lupus erythematosus (SLE) and Aicardi-Goutières syndrome (AGS), highlighting the dual role of cGAS as both a sentinel for infection and a potential driver of autoimmune pathology. Notably, the subcellular localization of cGAS is not still. Increasing recent researches have revealed that cGAS is also abundant within the nucleus, challenging the traditional view of it solely as a cytosolic nucleic acid sensor. Within the nucleus, cGAS exhibits non-canonical functions that are distinct from its canonical immunological role. First, cGAS exists in a state of stringent immunological silence in the nucleus, with mechanisms involving its competitive binding to histones and its post-translational modifications which block the activation of cGAS enzymatic activity, thus, effectively preventing it from mounting an autoimmune attack on genomic DNA. Second, cGAS plays a critical role in maintaining genomic stability. Upon DNA damage, cGAS is rapidly recruited to the lesion site and participates in the DNA damage repair process. Moreover, under conditions of DNA replication stress, cGAS contributes to the stabilization of replication forks, preventing the cell from entering a state of uncontrolled hyper-replication. Consequently, in light of the dual role of cGAS in both immune regulation and tumor development, the development of small-molecule drugs targeting cGAS holds significant therapeutic promise. This review summarizes the structural characteristics of cGAS and its canonical function as a pattern recognition receptor in the cytosol, including the types of pathogens it recognizes and the autoimmune responses resulting from erroneous recognition of self-DNA. It then focuses on its emerging non-canonical functions within the nucleus, detailing its nucleocytoplasmic shuttling, the mechanisms underlying its nuclear immune quiescence, and its role in mediating DNA damage repair and replication fork stabilization. Finally, the review discusses the progress and application prospects of small-molecule drugs targeting cGAS for the treatment of autoimmune diseases and cancer.

Acute kidney injury (AKI) is a prevalent and life-threatening clinical syndrome characterised by a rapid decline in renal function and diverse pathological etiologies. The condition has been demonstrated to be associated with elevated mortality rates and an increased risk of progression to chronic kidney disease. At present, clinicians depend heavily on conventional functional markers, such as serum creatinine and urine output, for the diagnosis and staging of the disease. It is evident that these conventional indicators characteristically manifest a considerable temporal delay and only undergo modification subsequent to considerable tissue damage. This severely restricts the timeframe for early detection and timely therapeutic intervention. Furthermore, standard markers fail to provide specific biological information regarding the underlying cellular injury mechanisms. The utilisation of advanced probe technologies in molecular imaging offers a robust alternative to overcome these inherent diagnostic limitations.This comprehensive review systematically evaluates recent progress in the design and application of two primary categories of molecular imaging tools for acute kidney disease, specifically reactive probes and enzyme-activated probes. Reactive probes are engineered to specifically interact with redox-active chemical species, including hydrogen peroxide, peroxynitrite, hypochlorous acid, and sulfur dioxide. Because oxidative stress constitutes a primary early event in acute renal tubular damage, these probes enable researchers and clinicians to visualize early cellular injury and radical accumulation well before global renal functional decline becomes evident. We discuss the application of these reactive probes across multiple imaging modalities including fluorescence imaging, magnetic resonance imaging (MRI), positron emission tomography (PET), and photoacoustic techniques. Photoacoustic imaging combines high spatial resolution with deep tissue penetration and has successfully demonstrated the ability to provide diagnostic alerts up to 12 h before any detectable rise in serum creatinine levels. Additionally, specific reactive probes have shown promising translational potential when tested by high-throughput screening in clinical human urine samples. Enzyme-activated probes target the specific catalytic activity of disease-relevant enzymes. These include well-documented renal tubular structural biomarkers such as NAG, GGT, and ALP, along with apoptosis-related caspases and specific nitroreductases. By responding only to enzymatic cleavage, these tools provide highly specific and pathology-directed imaging readouts. Recent structural design strategies in this field have advanced significantly beyond single-enzyme detection. Researchers are now focusing on sophisticated dual-target recognition to minimize background noise, multimodal integration to cross-validate imaging signals, and theranostic applications where probes simultaneously deliver diagnostic feedback and therapeutic agents to injured tissues. Nanotechnology serves as a fundamental enabler for realizing these advanced probe functions. By precisely optimizing nanoparticle parameters such as hydrodynamic size, surface charge, and targeting ligands, researchers can achieve amplified signal output, highly precise kidney delivery, and protection against premature degradation in the systemic circulation. For example, modifying surface charges can significantly enhance the active uptake of nanoprobes by damaged renal tubular epithelial cells.While preclinical probe development has progressed rapidly, moving these technologies into routine clinical practice remains a major challenge. We analyze the translational feasibility and current obstacles from biological, technological, and regulatory perspectives. Although biological targets such as KIM-1, FAP, and ALP have been validated in extensive patient cohorts, practical barriers severely limit their immediate clinical application. These obstacles involve complex changes in in vivo pharmacokinetics. During an acute injury episode, the extreme drop in the glomerular filtration rate alters probe clearance and can cause unwanted systemic accumulation or confusing background imaging signals. Other major hurdles include a lack of comprehensive long-term toxicity data and the absence of standardized manufacturing protocols to ensure batch-to-batch consistency. Future successful translation will require rigorous multi-center clinical studies to confirm the true diagnostic value of these probes over traditional markers. Researchers must also establish strict standardization of imaging procedures and comprehensive safety evaluations. Ultimately, this review provides a thorough reference framework for designing clinically translatable molecular probes and building a precision diagnostic imaging system for acute kidney injury.