Aristolochic acid I as an emerging biogenic contaminant involved in chronic kidney diseases: A comprehensive review on exposure pathways, environmental health issues and future challenges

Receptor-interacting protein kinase 1 confers autophagic promotion of gasdermin E-mediated pyroptosis in aristolochic acid-induced acute kidney injury

Aristolochic acid (AA) exposure is a severe public health concern worldwide. AAs damage the kidney with an inevitable acute phase that is similar to acute kidney injury (AKI). Gasdermin E (GSDME) is abundant in the kidney; thus; it-mediated pyroptosis might be essential in connecting cell death and inflammation and promoting AAs-AKI. However, the role and exact mechanism of pyroptosis in AAs-AKI have not been investigated. In this study, aristolochic acid I (AAI) was used to establish AKI models. The expression and translocation results showed GSDME-mediated pyroptosis in AAI-AKI. Knocking down GSDME attenuated AAI-induced cell death and transcription of proinflammatory cytokines. Mechanistic research inhibiting caspase (casp) 3, casp 8, and casp 9 with specific chemical antagonists demonstrated that GSDME was activated by cleaved casp 3. Furthermore, the kinase activity of upstream receptor-interacting protein kinase 1 (RIPK1) was significantly elevated, and inhibiting RIPK1 with specific inhibitors markedly improved AAI-induced cell damage. In addition, the level of autophagy was obviously increased. Pretreatment with a specific autophagic inhibitor (3-methyladenine) or knockdown of autophagic genes (Atg5 or Atg7) evidently reduced the activity of RIPK1 and downstream apoptosis and pyroptosis, thus attenuating AA-induced cell injury, which suggested that RIPK1 was a novel link conferring autophagic promotion of pyroptosis. These findings reveal GSDME-mediated pyroptosis for the first time in AAI-induced AKI, propose its novel role in the transcription of cytokines, and demonstrate that autophagy promotes pyroptosis via the RIPK1-dependent apoptotic pathway. This study promotes the understanding of the toxic effects and exact mechanisms of AAs. This will contribute to evaluating the environmental risk of AA exposure and might provide potential therapeutic targets for AA-AKI.

Magnetic quaternary ammonium polymer bearing porous agarose for selective extraction of Aristolochic acids in the plasma

Aristolochic acids (AAs) naturally occurring in the herbal genus Aristolochia are associated with a high risk of kidney failure, multiple tumors and cancers. However, approaches with high selectivity and rapidity for measuring AAs in biological samples are still inadequate. Inspired by the mechanism of AAs-induced nephrotoxicity, we designed a hybrid magnetic polymer-porous agarose (denoted as MNs@SiO2M@DNV-A), mimicking the effect of basic and aromatic residues of organic anion transporter 1 (OAT1) for efficient enriching aristolochic acid I (AA I) and aristolochic acid II (AA II) in the plasma. The monomers of vinylbenzyl trimethylammonium chloride (VBTAC), N-vinyl-2-pyrrolidinone (NVP) and divinylbenzene (DVB) were employed to construct the polymer layer, which provided a selective adsorption for AAs by multiple interactions. The porous agarose shell contributed to remove interfering proteins in the plasma samples. A magnetic solid-phase extraction (MSPE) based on the proposed composite enhanced the selectivity toward AA I and AA II in the plasma samples. In combination of HPLC analysis, the proposed method was proved to be applicable to fast and specific quantification of AAs in blood samples, which was characterized by a good linearity, high sensitivity, acceptable recovery, excellent repeatability and satisfactory reusability.

Aristolochic Acid Exposure via Dermal Contact or Inhalation of Herbal Powders: Evidence of Occupational Exposure in Herbalists with Urothelial Cancer

Emerging evidence showing urothelial cancer in herbalists is linked to aristolochic acid (AA) exposure; however, the exposure pathway remains unclear. Here, we show that dermal contact and inhalation of fine powders of AA-containing herbs are significant occupational AA exposure pathways for herbalists. We initiated the study by quantifying the amount of AA in the AA-containing powder deposited on gloves and face masks worn by the operators of an AA-containing herb grinding machine. Then, we measured the kinetics of dermal absorption and dissolution of AA from fine powders of AA-containing herbs into artificial sweat and surrogate lung fluid. Lastly, we quantified the mutagenic AA-DNA adduct levels formed in the kidneys of mice exposed to AA-containing fine powders through dermal contact. Our findings highlight an urgent occupational risk that should demand implementation of safety standards for herbalists exposed to AA-containing fine powders.

Comprehensive HRMS Screening and Risk Assessments of Aristolochic Acid Analogues in Asari Radix et Rhizoma and Related Commercial Health Products

Aristolochic acid analogues (AAAs) are well-known toxins. We performed the first comprehensive screening on AAAs in Asari Radix et Rhizoma (underground part of Asarum heterotropoides Schmidt), the only Aristolochiaceae plant widely used in clinical practice. LC-HRMS revealed 70 trace AAAs using polygonal mass defect filtering and precursor ion list strategies, 38 of which were newly discovered in A. heterotropoides. UHPLC-QTrap-MS/MS was then utilized for quantitative/semiquantitative analysis of 26 abundant compounds. Seventeen AAAs were detected from 91 batches of A. heterotropoides and 20 AAAs from 166 consumable products. For 141 Asari-containing proprietary products, aristolactam I and aristolactam II-glucoside exhibited the widest distribution, present in 98% products. AA IVa was the most abundant, detected in 91%. Notably, 60% of the products contained AA I (0.03-0.79 ppm). The safety was assessed using linear extrapolation, permitted daily exposure, cumulative amount, and the margin of exposure. It is recommended that AA I content be limited to 3 ppm.

Development and Application of a Comprehensive Nontargeted Screening Strategy for Aristolochic Acid Analogues

Aristolochic acid analogs (AAAs) are naturally occurring carcinogenic and toxic compounds that pose a safety threat to pharmaceuticals and the environment. It is challenging to screen AAAs due to their lack of characteristic mass spectral fragmentation and their presence of structural diversity. A comprehensive nontargeted screening strategy was proposed by taking into account diverse factors and incorporating various self-developed techniques, and a Python3-based toolkit called AAAs_finder was developed for its implementation. The main procedures consist of virtual structure and ultraviolet and visible (UV) spectra database creation, exact mass and UV spectra-based suspect data extraction, tandem mass spectra (MS/MS) anthropomorphic interpretation, and multicondition retention time (RT) prediction-based candidate structures ranking. To initially assess screening feasibility, eight hypothetical unknown samples were subjected to nontargeted screening using the AAAs_finder toolkit and two other advanced tools. The results showed that the former successfully identified all, while the latter two only managed to identify two and three, respectively, indicating that our strategy was more feasible. After that, the strategy was carefully evaluated for false positives and false negatives, instrument dependence, reproducibility, and sensitivity. After the evaluation, the strategy was successfully applied to the screening of AAAs in real samples, such as herbal medicine, spiked soil, and water. Overall, this study proposed a nontargeted screening strategy and toolkit independent of characteristic mass spectral fragmentation and able to overcome challenges posed by structural diversity for the AAAs screening, which is also valuable for other classes of compounds.

SGLT2 inhibitor dapagliflozin protects the kidney in a murine model of Balkan nephropathy

Proximal tubular uptake of aristolochic acid (AA) forms aristolactam (AL)-DNA adducts, which cause a p53/p21-mediated DNA damage response and acute tubular injury. Recurrent AA exposure causes kidney function loss and fibrosis in humans (Balkan endemic nephropathy) and mice and is a model of (acute kidney injury) AKI to chronic kidney disease (CKD) transition. Inhibitors of the proximal tubule sodium-glucose transporter SGLT2 can protect against CKD progression, but their effect on AA-induced kidney injury remains unknown. C57BL/6J mice (15-wk-old) were administered vehicle or AA every 3 days for 3 wk (10 and 3 mg/kg ip in females and males, respectively). Dapagliflozin (dapa, 0.01 g/kg diet) or vehicle was initiated 7 days prior to AA injections. All dapa effects were sex independent, including a robust glycosuria. Dapa lowered urinary kidney-injury molecule 1 (KIM-1) and albumin (both normalized to creatinine) after the last AA injection and kidney mRNA expression of early DNA damage response markers (p53 and p21) 3 wk later at the study end. Dapa also attenuated AA-induced increases in plasma creatinine as well as AA-induced up-regulation of renal pro-senescence, pro-inflammatory and pro-fibrotic genes, and kidney collagen staining. When assessed 1 day after a single AA injection, dapa pretreatment attenuated AL-DNA adduct formation by 10 and 20% in kidney and liver, respectively, associated with reduced p21 expression. Initiating dapa application after the last AA injection also improved kidney outcome but in a less robust manner. In conclusion, the first evidence is presented that pretreatment with an SGLT2 inhibitor can attenuate the AA-induced DNA damage response and subsequent nephropathy.NEW & NOTEWORTHY Recurrent exposure to aristolochic acid (AA) causes kidney function loss and fibrosis in mice and in humans, e.g., in the form of the endemic Balkan nephropathy. Inhibitors of the proximal tubule sodium-glucose transporter SGLT2 can protect against CKD progression, but their effect on AA-induced kidney injury remains unknown. Here we provide the first evidence in a murine model that pretreatment with an SGLT2 inhibitor can attenuate the AA-induced DNA damage response and subsequent nephropathy.

Rapid and selective removal of aristolochic acid I in natural products by vinylene-linked iCOF resins

Rapid, efficient, and selective removal of toxicants such as aristolochic acid I (AAI) from complex natural product systems is of great significance for the safe use of herbal medicines or medicine-food plants. Addressing this challenge, we develop a high-performance separation approach based on ionic covalent organic frameworks (iCOFs) to separate and remove AAI. Two vinylene-linked iCOFs (NKCOF-46-Br- and NKCOF-55-Br-) with high crystallinity are fabricated in a green and scalable fashion via a melt polymerization synthesis method. The resulting materials exhibit a uniform morphology, high stability, fast equilibrium time, and superior affinity and selectivity for AAI. Compared to conventional separation media, NKCOF-46-Br- and NKCOF-55-Br- achieve the record high adsorption capacities of 246.0 mg g-1 and 178.4 mg g-1, respectively. Various investigations reveal that the positively charged framework and favorable pore microenvironment of iCOFs contribute to their high selectivity and adsorption efficiency. Moreover, the iCOFs exhibit excellent biocompatibility by in vivo toxicity assays. This study paves a new avenue for the rapid, selective and efficient removal of toxicants from complex natural systems.

Detection and Removal of Aristolochic Acid in Natural Plants, Pharmaceuticals, and Environmental and Biological Samples: A Review

Aristolochic acids (AAs) are a toxic substance present in certain natural plants. Direct human exposure to these plants containing AAs leads to a severe and irreversible condition known as aristolochic acid nephropathy (AAN). Additionally, AAs accumulation in the food chain through environmental mediators can trigger Balkan endemic nephropathy (BEN), an environmental variant of AAN. This paper presents a concise overview of the oncogenic pathways associated with AAs and explores the various routes of environmental exposure to AAs. The detection and removal of AAs in natural plants, drugs, and environmental and biological samples were classified and summarized, and the advantages and disadvantages of the various methods were analyzed. It is hoped that this review can provide effective insights into the detection and removal of AAs in the future.

Molecular Basis of Tumorigenesis of Bladder Cancer and Emerging Concepts in Developing Therapeutic Targets

BACKGROUND

Advanced urothelial carcinoma (UC) is an aggressive disease whose mutagenic processes are yet to be elucidated. Targeted therapies are urgently needed, but the road from bench to bedside is slowly progressing. In this review, we discuss urothelial carcinoma etiology, along with the most recent advances in UC candidate targeted therapies.

METHODOLOGY

A comprehensive database search was performed. We aimed to review the most recent updates on UC genomics and targeted therapies. Pre-clinical as well as clinical studies were included.

RESULTS

Our review highlights the advances in understanding the molecular basis of urothelial tumorigenesis, including smoking, chemical parasitic carcinogens, inheritance, and APOBEC3 editing enzymes. We discussed how these factors contributed to the current mutational landscape of UC. Therapeutic options for UC are still very limited. However, several promising therapeutic approaches are in development to leverage our knowledge of molecular targets, such as targeting fibroblast growth factor receptors (FGFR), DNA damage repair pathways, and HER2.

CONCLUSIONS

Blindly testing targeted therapies based on other cancer data is not sufficient. UC-specific biomarkers are needed to precisely use the appropriate drug for the appropriate population. More efforts to understand UC biology and evolution are urgently needed.

Efficient separation of aristolochic acid I from Caulis aristolochiae manshuriensis (Guan-mu-tong) with copper mediated magnetic molecularly imprinted polymer

Screening bioactive compounds from natural products is one of the most effective ways for new drug research and development. However, obtaining a single extract component on a large scale and with high purity from a complex matrix is still an arduous and challenging task. Herein, one metal mediated magnetic molecularly imprinted polymer (mMIP) was rationally designed and prepared for specifically capturing Aristolochic acid I (AAI). The preparation was done with copper(II) as binding pivot, (3-aminopropyl) triethoxysilane as functional monomer, and Fe3O4 as core, by a one-step sol-gel method. Under the optimized conditions, the apparent maximum binding amount of copper mediated mMIP (Cu-mMIP) reaches as high as 349.72 mg g-1, the highest among the reported AAI-MIPs. Moreover, the nanoparticles exhibit excellent specificity and selectivity, good reproducibility and stability, high superparamagnetism (60.32 emu g-1), and high imprinting efficiency (an imprinting factor of 7). By simulating an industrial-scale separation, 16.56 mg AAI (purity of 95.11%) is obtained after six cycles with 100 mg nanoparticles from 20 g Caulis aristolochiae manshuriensis (Guan-mu-tong). Notably, this takes only 3 hours and consumes 50 mL of methanol. The study provides a potent tool for the green, fast, and specific extraction of high-purity ingredients from natural plants in the manufacturing industry and conventional analysis in the lab.

Generation of a high-affinity DNA aptamer for on-site screening of toxic aristolochic acid I in herbal medicines and botanical products

Aristolochic Acid I (AAI) is an environmental and foodborne toxin found in the Aristolochia and Asarum species of plants that are widespread all over the world. Therefore, there is an urgent need to develop a sensitive and specific biosensor for identifying AAI. Aptamers as a powerful biorecognition element provide the most viable options for solving this problem. In this study, we used library-immobilized SELEX to isolate an AAI-specific aptamer with a K_D value of 86 ± 13 nM. To verify the practicability of the selected aptamer, a label-free colorimetric aptasensor was designed. This aptasensor exhibited a low detection limit of 225 nM. Besides, it had been further applied for the determination of AAI in real samples and the recoveries ranged from 97.9% to 102.4%. In the future, AAI aptamer will provide a promising tool for safety evaluation in various fields of agriculture, food, and medication.

Parametric MRI Detects Aristolochic Acid Induced Acute Kidney Injury

Exposure to aristolochic acid (AA) is of increased concern due to carcinogenic and nephrotoxic effects, and incidence of aristolochic acid nephropathy (AAN) is increasing. This study characterizes renal alterations during the acute phase of AAN using parametric magnetic resonance imaging (MRI). An AAN and a control group of male Wistar rats received administration of aristolochic acid I (AAI) and polyethylene glycol (PEG), respectively, for six days. Both groups underwent MRI before and 2, 4 and 6 days after AAI or PEG administration. T₂ relaxation times and apparent diffusion coefficients (ADCs) were determined for four renal layers. Serum creatinine levels (sCr) and blood urea nitrogen (BUN) were measured. Tubular injury scores (TIS) were evaluated based on histologic findings. Increased T₂ values were detected since day 2 in the AAN group, but decreased ADCs and increased sCr levels and BUN were not detected until day 4. Significant linear correlations were observed between T₂ of the cortex and the outer stripe of outer medulla and TIS. Our results demonstrate that parametric MRI facilitates early detection of renal injury induced by AAI in a rat model. T₂ mapping may be a valuable tool for assessing kidney injury during the acute phase of AAN.

Pharmacological mechanisms of Fuzheng Huayu formula for Aristolochic acid I-induced kidney fibrosis through network pharmacology

Renal fibrosis, characterized by the destruction of renal tubules and interstitial capillaries and the accumulation of extracellular matrix proteins, is a common outcome of chronic renal diseases and has a wide spectrum of etiologies. Fibrosis can affect any organ and has similar pathological mechanisms. Fuzheng Huayu formula (FZHY), as the approved anti-liver fibrosis medicine in China, also can inhibit the kidney fibrosis induced by HgCl₂ or unilateral ureteral obstruction. However, little is known about the mechanisms underlying the beneficial effects of FZHY on renal fibrosis. This study aimed to identify the mechanisms of FZHY acts on renal fibrosis through network pharmacological analysis and in vivo experiments. Data from online databases were mined and screened to predict the target related genes of FZHY acts on renal fibrosis. The STRING and Cytoscape were used to construct the protein-protein interaction (PPI) networks for FZHY and CKD target proteins. Mouse models with CKD induced by Aristolochic Acid I (AAI) were used to validate the effects of FZHY on renal fibrosis and their underlying mechanisms by detecting kidney function, renal fibrosis, and related intersection genes. A total of 129 FZHY-CKD crossover proteins were filtered and constructed into a protein-protein interaction network complex and designated as the potential targets of FZHY. One of the highest-scoring genes, FOS, and its related signaling pathways were more activated in CKD. The results demonstrated that FZHY can exert an anti-renal fibrosis effect by improving the levels of serum creatinine and blood urea nitrogen and alleviating excessive collagen deposition in kidney tissue, FZHY also could reduce the levels of TNF-α, IL-1β, and IL-6 and inhibit the expression of MAPK/FOS signal molecules. Our study findings provide insights into predicting the effects of FZHY on CKD through network pharmacology. FZHY can protect the kidney from inflammatory injury caused by AAI and can antagonize inflammatory factor-stimulated MAPK/FOS activation in fibrotic kidneys. These effects constitute the mechanisms of FZHY for renal fibrosis.

Uptake, Translocation, and Fate of Carcinogenic Aristolochic Acid in Typical Vegetables in Soil-Plant Systems

When Aristolochia plants wilt and decay, aristolochic acids (AAs) are released into the soil, causing soil contamination. It has been demonstrated that aristolochic acid can be accumulated and enriched in crops through plant uptake. However, there is a lack of systematic studies on the migration and accumulation of AAs in a realistic simulated soil environment. In this study, Aristolochia herbal extracts were mixed with soil for growing three typical vegetables: lettuce, celery, and tomato. The contents of AAs in the above-mentioned plants were determined by an established highly sensitive LC-MS/MS method to study the migration and accumulation of AAs. We found that AAs in the soil can be transferred and accumulated in plants. AAs first entered the roots, which were more likely to accumulate AAs, and partially entered the above-ground parts. This further confirms that AAs can enter the food chain through plants and can have serious effects on human health. It was also shown that plants with vigorous growth and a large size absorbed AAs from the soil at a faster rate. The more AAs present in the soil, the more they accumulated in the plant.

Aristolochic acid-associated cancers: a public health risk in need of global action

Aristolochic acids (AAs) are a group of naturally occurring compounds present in many plant species of the Aristolochiaceae family. Exposure to AA is a significant risk factor for severe nephropathy, and urological and hepatobiliary cancers (among others) that are often recurrent and characterized by the prominent mutational fingerprint of AA. However, herbal medicinal products that contain AA continue to be manufactured and marketed worldwide with inadequate regulation, and possible environmental exposure routes receive little attention. As the trade of food and dietary supplements becomes increasingly globalized, we propose that further inaction on curtailing AA exposure will have far-reaching negative effects on the disease trends of AA-associated cancers. Our Review aims to systematically present the historical and current evidence for the mutagenicity and carcinogenicity of AA, and the effect of removing sources of AA exposure on cancer incidence trends. We discuss the persisting challenges of assessing the scale of AA-related carcinogenicity, and the obstacles that must be overcome in curbing AA exposure and preventing associated cancers. Overall, this Review aims to strengthen the case for the implementation of prevention measures against AA's multifaceted, detrimental and potentially fully preventable effects on human cancer development.