ARISTOLOCHIC ACID (AA)

Terisse Brocato

Miguel Pena

Stephen Esquivel

Victor Salgado

WHAT IS A TOXIN?

A toxin is a substance (poisonous) produced by an organism that may have an adverse affect on another organism.

Toxins can be produced as a defense mechanism for an organism as well as an offensive mechanism.

WHAT IS ARISTOLOCHIC ACID? Aristolochic Acid is a family of

compounds that are commonly found in the Aristolochiaceae family of plants that produce carcinogenic, mutagenic, and nephrotoxic effects.

Aristolochic Acid is a commonly used ingredient in various Chinese herbal medicines as well as other herbal remedies.

AA

Aristolochic acid was first determined to be toxic when the makers of a slimming drug in Belgium was replaced with AA.

Hundreds of cases of Aristolochic acid nephropathy (AAN) came about due to the intake of AA which was used in many herbal remedies all over the world.

ARISTOLOCHIC ACID HISTORY-USES IN ANCIENT TIMES

• Obstetrics treatment• Snakebites• Scorpion stings• Fever• Infection• Diarrhea• Inflammation

ARISTOLOCHIC ACID HISTORY-USES IN MODERN TIMES

Arthritis Gout Rheumatism Festering wounds Weight-loss Eczema Hepatitis B Pain relief

PLANTS WHICH CONTAIN AA

Aristolochia debilis Aristolochia manshuriensis Aristolochia fangchi Aristolochia contorta Little Brown Jug Canadian snakeroot/ Wild ginger Virginia snakeroot Asarum canadense

ARISTOLOCHIA PLANTS IN THE U.S.

ASARUM PLANTS IN THE U.S.

HERBAL REMEDIES CONTAINING AA

Tian-Xian-Teng Ma-Dou-Ling Qingmuxiang Guangfangji Guanmutong han fang ba zheng san Dao Chi Pian Chuan Xiong Cha Tiao San Lung Tan Xie Gan

ARISTOLOCHIC ACID NEPHROPATHY OUTBREAKS (2008)

USA:2

UK:4

France:4

Spain:1

Belgium: 128

Germany: 1

China:116

Korea:1

Japan:6

Taiwan:33

The major outbreaks were in Belgium and China where containing AA was common (weight loss drug, and treatment of urinary and cardiovascular disease)(Debelle et al).

STRUCTURE

The two major components of Aristolochic Acid are Aristolochic acid I (AAI) and Aristolochic acid II (AAII)

COMPLICATIONS

1. Kidney Problems (AA is a nephrotoxin)

2. Cancer (due to metabolism of AA)

3. Heart problems

KIDNEY PROBLEMS ASSOCIATED WITH AA

Shrunken kidneys (majority of cases)

Asymmetric kidneys (half of cases)

Interstitial fibrosis (thickening of kidney

wall fibers)

Atrophy of kidneys (degeneration and

death of kidney cells)

NEPHROTOXIC

This is a picture of a normal functioning kidney and its functions in the body.

NEPHROTOXIN CONT.

NEPHROTOXIN CONT.

A patient subjected to AA will have the following problems with their kidneys.

CANCER ASSOCIATED WITH AA

39.5% of patients with a kidney transplant are diagnosed with bladder urothelial carcinoma.

Cancer is caused by DNA adducts which form by AA metabolism.

Animal tests show that DNA adducts remain in animal’s bodies throughout their life (this has not yet been tested in humans).

HEART PROBLEMS ASSOCIATED WITH AA

30-50% of patients diagnosed with AAN (Aristolochic acid nephropathy-kidney damage due to taking AA) have aortic insufficiency (where the aortic valve is not able to close completely, causing backflow of blood from the aorta to the left ventricle).

This causes the heart to pump harder in order to pump enough blood to the body.

MECHANISM

The products of metabolism, dA-AAI/II and dG-AAI/II, are DNA adducts which form mutations in DNA

MECHANISM CONT. Metabolism of AA in the body forms DNA

adducts (dA-AAI/II, dG-AAI/II) which are known to cause particular mutations (mutations depend on species).

In humans: there is an ATT->TAG mutation in the p53 gene.

In rodents: there is an AT->TA mutation in the H-ras proto-oncogene.

Both mutations cause tumorigenesis (formation of tumors).

RENAL FIBROSISMetabolism of Aristolochic acid is known to cause fibrosis of the kidneys. Scientist suspect causation can happen via small doses over a long time or by large doses at intermediate intervals. A) shows a complete loss of microvilli of the inner kidneys. B) shows disruption of the cellular adhesion molecules between cells.

TGF 1 BETA/SMAD Transforming Growth Factor 1 beta and

its conjugate SMAd complex may play a role in Aristolochic acid signaling and metabolism.In A 2009 study scientists chronically exposed mice with the wild-type smad3 mediator and mice with knock-out smad3 mediator with aristolochic acid. The wild-type mice were found to have nephropathy, characterized by fibrosis and scarring. The knockout mice did not exhibit Nephropathy.

EXAMPLE OF TGF BETA SIGNALLING

TGF 1 BETA SIGNALING

TGF 1 BETA is a known factor in tissue scaring by inducing fibrosis via the downstream SMAD3 mediator. Aristolochinc acid was found to cause no fibrosis in mice that did not have have functional SMAD3 receptors. This a mechanistic look at how Aristolochic acid causes nephropathy.

EPITHELIAL-MESENCHYMAL TRANSITION (EMT)

Compromisation of the TGF-1 Beta signal causes dissolution of the connective properties of epithelial cells which acquire a mesenchymal phenotype. Actin reorganization and stress fiber formation support migration and invasion of epithelial cells to other sites. Aristolochic acid is found to induce fibrosis(scaring) via the TGF1 Beta/SMAD3 pathway.

BEN Balkin-endemic nephropathy (BEN) Patients suffering from BEN are found to

have all the same cancers, renal problems, and overall same symptoms, but with minor variations as patients with Aristolochic acid nephropathy (AAN).

It is highly suspected that BEN is caused by long-term exposure to small amounts of AA.

This conclusion is popular due to the fact that many third-world countries use herbal remedies containing AA for various reasons: to treat diseases, sickness, pain, etc.

BEN CONT.

At least 25000 individuals are suffering with BEN in Bulgaria, Bosnia, Croatia, Romania, and Serbia.

Total people at risk in these countries may be higher than 100,000 (Debelle et al.)

Most citizens in these places do not have adequate access to information on the medicines which they take, nor is the medicine labeled adequately.

POSSIBLE TREATMENTS

Short Term-Removal of toxin from the body

Dialysis (if needed) Kidney Transplant (severe cases)

Supportive Therapy in acute phase Fluid and electrolyte management Management of hypertension Dialysis for acute severe renal failure

CONCLUSION High risk of substitution in herbal

products causes misperception of what an individual is taking.

Testing of herbal remedies using high-liquid chromatography or some characterization method should be used before allowing any herbal remedy to be ingested.

AA should not be ingested for any reason, unfortunately Chinese medicine and Indian folk medicine still use AA in their herbal remedies.

BIBLIOGRAPHY Debelle et al. “Aristolochic acid nephropathy: A worldwide

problem”. 2008 International Society of Nephrology. Kidney International (2008) 74, 158–169.

Jain Xu, et al. “TGF--induced epithelial to mesenchymal transition” Cell Reserch. Vol 19. 157-172. (2009)

Li Zhou, et al. “Mechanism of chronic aristolochic acid nephropathy: role of Smad3” American Journal of Renal Physiology. Vol 298. no. 4. 1006-1017 (2010)

Lord et al. “DNA Adducts and p53 Mutations in a Patient With Aristolochic Acid–Associated Nephropathy”. American Journal of Kidney Diseases, Vol 43, No 4 (April), 2004: E18.

Mary Packard, et al. “Wnts and TGF in synaptogenesis: old friends signalling at new places” Nature Reviews Neuroscience.

Vol 4. 113-120 (February 2003) Mengs et al. “The Carcinogenic Action of Aristolochic Acid in Rats”.

Archives of Toxicology (1982) 51:107-119. National Toxicology Program,U.S. Department of Health and

Human Services. “Report on Carcinogens- Background Document for Aristolochic Acids”. September 2008.

BIBLIOGRAPHY CONT. Schmeiser et al. “Detection of DNA Adducts Formed by Aristolochic

Acid in Renal Tissue from Patients with Chinese Herbs Nephropathy”. Cancer Research Vol 56, 2025-2028, May I. I996.

Shaohua et al. “Fatal renal failure due to the Chinese herb ‘‘GuanMu Tong’’ (Aristolochia manshuriensis): Autopsy findings and

review of literature”. Forensic Science International 199 (2010) e5–e7.

Stiborov et al. “Bioactivation versus Detoxication of the Urothelial Carcinogen Aristolochic Acid I by Human Cytochrome P450 1A1

and 1A2”. ToxicologicalSciences 125(2), 345–358 (2012). Yee-Yung Ng, et al. “Tubular epithelial-myofibroblast transdifferentiation

in progressive tubulointerstitial fibrosis in 5/6 nephrectomized rats” Kidney International. Vol 54. 864-876. (1998)

Youhua Liu. “Renal fibrosis: New insights into the pathogenesis and therapeutics” Kidney International. Vol 69. 213-217. (2006)

Zeng et al. “Aristolochic Acid I Induced Autophagy Extenuates Cell Apoptosis via ERK 1/2 Pathway in Renal Tubular Epithelial Cells”. Department of Nephrology. January 2012, Volume 7, Issue 1, e30312.