Aristolochic Acid I Induces Ovarian Toxicity by Inhibition of Akt Phosphorylation

Aristolochic acid I exposure decreases oocyte quality

Oocyte quality is a determinant of a successful pregnancy. The final step of oocyte development is oocyte maturation, which is susceptible to environmental exposures. Aristolochic acids (AAs), widely existing in Aristolochia and Asarum plants that have been used in traditional medicine, can result in a smaller ovary and fewer superovulated oocytes after in vivo exposure to mice. However, whether AAs affect oocyte maturation and the underlying mechanism(s) are unclear. In this study, we focused on the effect of Aristolochic acid I (AAI), a major compound of AAs, on the maturation of in vitro cultured mouse oocytes. We showed that AAI exposure significantly decreased oocyte quality, including elevated aneuploidy, accompanied by aberrant chiasma patterns and spindle organization, and decreased first polar body extrusion and fertilization capability. Moreover, embryo development potential was also dramatically decreased. Further analyses revealed that AAI exposure significantly decreased mitochondrial membrane potential and ATP synthesis and increased the level of reactive oxygen species (ROS), implying impaired mitochondrial function. Insufficient ATP supply can cause aberrant spindle assembly and excessive ROS can cause premature loss of sister chromatid cohesion and thus alterations in chiasma patterns. Both aberrant spindles and changed chiasma patterns can contribute to chromosome misalignment and thus aneuploidy. Therefore, AAI exposure decreases oocyte quality probably via impairing mitochondrial function.

Fetal exposure of Aristolochic Acid I undermines ovarian reserve by disturbing primordial folliculogenesis

The primordial follicle pool established in early life determines the ovarian reserve in the female reproductive lifespan. Premature exhaustion of primordial follicles contributes to primary ovarian insufficiency (POI), that is dependent by the initial size of the primordial follicle pool and by the rate of its activation and depletion. AAI, a powerful nephrotoxin with carcinogenic potential, is present in the Aristolochiaceae species, which can release AAI into soil as a persistent pollutant. In order to assess the potential risk of Aristolochic Acid I (AAI) exposure on mammalian oogenesis, we uncovered its adverse effect on primordial folliculogenesis in the neonatal mouse ovary and its effect on female fertility in adulthood. Pregnant mice were orally administrated with doses of AAI without hepatic or renal toxicity during late-gestation. Ovaries from offspring of administered female displayed gross aberrations during primordial folliculogenesis. Also, unenclosed oocytes in germ-cell cysts showed increased DNA damage. Furthermore, several key factors, including NANOS3, SOX9, KLF4, that govern early gonad's differentiation were abnormally expressed in the exposed ovary, while the follicle formation was partially restored by knockdown of Nanos3 or sox9. In adulthood, these aberrations evolved into a significant reduction in offspring number and impaired ovarian reserve. Together, our results show that AAI influences primordial folliculogenesis and, importantly, affected female fertility. This study shows that administration of drugs herbs or consumption of vegetables that contain AAs during pregnancy may adversely influence the fertility of offspring.

Aristolochic acid and the risk of cancers in patients with type 2 diabetes: Nationwide population-based cohort study

BACKGROUND

Both aristolochic acid (AA) exposure and diabetic can increase risk of certain cancers,whetherAAexposureincreases cancer risk in diabetic patientsisunknown. The purpose of this study was to investigate the association between the use of Chinese herbal products containing AA and the risk of cancer in diabetic patients.

METHODS

A cohort study was conducted using the National Health Insurance Research Database in Taiwan. Patients older than 18 years who were diagnosed with diabetes between 1997 and 2010 were enrolled in our cohort. The use of Chinese herbal products containing AA was recorded from the beginning of 1997 until the ban of herbs containing AA in November 2003. Patients were individually tracked to identify cancer incidence between 1997 and 2013. Only patients who visited traditional Chinese medicine clinics between 1997 and 1 year before the end of follow-up were included in the cohort to ensure comparability. Cox proportional hazards regression was used to calculate the hazard ratio for the association between the use of Chinese herbal products containing AA and the occurrence of cancer.

RESULTS

Among the 430 377 male and 431 956 female patients with diabetes enrolled in our cohort, 37 554 and 31 535 cancer diagnoses were recorded during the study period, respectively. The use of AA-containing herbal products was associated with a significantly higher risk of liver, colorectum, kidney, bladder, prostate, pelvis, and ureter cancer in a dose-dependent manner. An increased risk of extrahepatic bile duct cancer in women was also associated with AA exposure at doses of more than 500 mg.

CONCLUSIONS

Association between AA exposure and the risk of some cancers were found in this study. AA exposure might increase risk of kidney,bladder,pelvis, ureter,liver,colorectum,andprostatecancer in all patientsandextrahepatic bile duct cancerin women.

Exposure to aristolochic acid I compromises the maturational competency of porcine oocytes via oxidative stress-induced DNA damage

Aristolochic acid (AA) is a class of carcinogenic and nephrotoxic nitrophenanthrene carboxylic acids naturally found in Aristolochia plants. These plants have been widely used as herbal medicines and also enter the human food chain as the persistent soil pollutants. It has been known that AA exposure is implicated in multiple cancer types, kidney failure and ovarian dysfunction. However, whether AA exposure would influence the oocyte quality has not yet determined. Here, we document that AAI has the negative effects on the competency of oocyte maturation and fertilization. We show that AAI exposure leads to the oocyte meiotic failure via impairing the meiotic apparatus, displaying a prominently defective spindle assembly, actin dynamics and mitochondrial integrity. AAI exposure also causes the abnormal distribution of cortical granules and ovastacin, which is consistent with the observation that fewer sperm bound to the zona pellucida surrounding the unfertilized AAI-exposed eggs, contributing to the fertilization failure. In addition, AAI exposure induces the increased levels of ROS, DNA damage and early apoptosis in porcine oocytes. Collectively, we demonstrate that AAI exposure perturbs the oocyte meiotic progression and fertilization capacity via disruption of both nuclear maturation and cytoplasmic maturation of oocyte, which might be caused by the excessive oxidative stress-induced DNA damage and apoptosis.

Systematic Overview of Aristolochic Acids: Nephrotoxicity, Carcinogenicity, and Underlying Mechanisms

Aristolochic acids (AAs) are a group of toxins commonly present in the plants of genus Aristolochia and Asarum, which are spread all over the world. Since the 1990s, AA-induced nephropathy (AAN) and upper tract urothelial carcinoma (UTUC) have been reported in many countries. The underlying mechanisms of AAN and AA-induced UTUC have been extensively investigated. AA-derived DNA adducts are recognized as specific biomarkers of AA exposure, and a mutational signature predominantly characterized by A→T transversions has been detected in AA-induced UTUC tumor tissues. In addition, various enzymes and organic anion transporters are involved in AA-induced adverse reactions. The progressive lesions and mutational events initiated by AAs are irreversible, and no effective therapeutic regimen for AAN and AA-induced UTUC has been established until now. Because of several warnings on the toxic effects of AAs by the US Food and Drug Administration and the regulatory authorities of some other countries, the sale and use of AA-containing products have been banned or restricted in most countries. However, AA-related adverse events still occur, especially in the Asian and Balkan regions. Therefore, the use of AA-containing herbal remedies and the consumption of food contaminated by AAs still carry high risk. More strict precautions should be taken to protect the public from AA exposure.

Recognition of the toxicity of aristolochic acid

WHAT IS KNOWN AND OBJECTIVE

Aristolochic acid (AA) is an abundant compound in Aristolochia plants and various natural herbs. In the 1990s, a slimming formula used in Belgium that contains Aristolochia fangchi was reported to cause kidney damage and bladder cancer, and aristolochic acid nephropathy (AAN) is now well recognized worldwide. In October 2017, researchers reported an AA signature that is closely associated with hepatocellular carcinoma (HCC) worldwide.

COMMENT

There are differing opinions on the toxicity of AA, and different countries have taken different measures to address the issue. There is a lack of clarity on the causal role of AA in hepatocarcinogenesis and on the potential underlying mechanisms for the reported nephrotoxicity and carcinogenicity. The toxicity of AA differs depending on gender and age, and other risk factors that could explain the variability in the toxicity of AA remain to be identified.

WHAT IS NEW AND CONCLUSION

Whether preparations containing AA, such as many Chinese medicines, should be used remains controversial, and this issue warrants further investigation before definite conclusions can be drawn.

Vitamin E (α‑tocopherol) ameliorates aristolochic acid‑induced renal tubular epithelial cell death by attenuating oxidative stress and caspase‑3 activation

Aristolochic acid (AA) is a component identified in traditional Chinese remedies for the treatment of arthritic pain, coughs and gastrointestinal symptoms. However, previous studies have indicated that AA can induce oxidative stress in renal cells leading to nephropathy. α-tocopherol exists in numerous types of food, such as nuts, and belongs to the vitamin E isoform family. It possesses antioxidant activities and has been used previously for clinical applications. Therefore, the aim of the present study was to determine whether α-tocopherol could reduce AA-induced oxidative stress and renal cell cytotoxicity, determined by cell survival rate, reactive oxygen species detection and apoptotic features. The results indicated that AA markedly induced H₂O₂ levels and caspase-3 activity in renal tubular epithelial cells. Notably, the presence of α-tocopherol inhibited AA-induced H₂O₂ and caspase-3 activity. The present study demonstrated that antioxidant mechanisms of α-tocopherol may be involved in the increased survival rates from AA-induced cell injury.