Mouse study links triclosan, a common antimicrobial, to colonic inflammation

A large research team led by senior author Guodong Zhang at the University of Massachusetts Amherst reports that the antimicrobial ingredient triclosan, found in hand soaps and toothpastes among other products, could have adverse effects on colonic inflammation and colon cancer by altering gut microbiota, the microbes found in our intestines.

The study reported in Science Translational Medicine suggests that short-time treatment with low-dose triclosan caused low-grade colonic inflammation, and exaggerated disease development of colitis and colitis-associated colon cancer in mice, Zhang says. "These results, for the first time, suggest that triclosan could have adverse effects on gut health," he notes.

Co-first authors Haixia Yang and Weicang Wang, both from the Zhang laboratory in the food science department at UMass Amherst, point out that triclosan is among the most widely used antimicrobial ingredients and is found in more than 2,000 consumer products. They note that a National Health and Nutrition Examination Survey showed that triclosan was detected in about 75 percent of the urine samples of individuals tested in the United States and it is among the top ten pollutants found in U.S. rivers.

"Because this compound is so widely used, our study suggests that there is an urgent need to further evaluate the impact of triclosan exposure on gut health in preparation for the potential establishment of further regulatory policies," says Yang, a postdoctoral fellow in Zhang laboratory.

In this study, the 21-member team that included 12 UMass Amherst researchers, investigated the effects of triclosan on colonic inflammation and colon cancer using several mouse models. In all mouse models tested, triclosan promoted colonic inflammation and colon tumorigenesis, Zhang reports.

His co-author, food scientist Hang Xiao, adds, "In particular, we used a genetically engineered mouse model which develops spontaneous inflammatory bowel disease or IBD. Also, treatment with triclosan significantly increased disease development of IBD in the mice, suggesting that IBD patients may need to reduce exposure to this compound."

In a series of experiments designed to explore mechanisms, the research team found that gut microbiota is critical for the observed adverse effects of triclosan. Feeding triclosan to mice reduced the diversity and changed the composition of the gut microbiome, a result similar to what was observed in a human study conducted by others, Zhang says.

Also, triclosan had no effect in a germ-free mouse model where there is no gut microbiome present, nor in a genetically engineered mouse model where there is no Toll-like receptor 4 (TLR4) - an important mediator for host-microbiota communications. "This is strong evidence that gut microbiota is required for the biological effects of triclosan" Zhang points out.

In an editorial note accompanying the article, the journal says, "Triclosan exposure is practically unavoidable in the United States, but little is known how ingestion may affect our health." This study observed that triclosan altered mouse gut microbiota, increased inflammation, increased the severity of colitis symptoms and spurred colitis-associated colon cancer cell growth. Though limited to mouse models, "this work suggests that the effects of triclosan on human health should be examined more closely," editors noted.

Ref : http://www.umass.edu/newsoffice/article/triclosan-common-antimicrobial-ingredient

http://stm.sciencemag.org/content/10/443/eaan4116

Antibacterial in your toothpaste may combat severe lung disease

In continuation of my update on Triclosan

A common antibacterial substance found in toothpaste may combat life-threatening diseases such as cystic fibrosis, or CF, when combined with an already FDA-approved drug.

Michigan State University researchers have found that when triclosan, a substance that reduces or prevents bacteria from growing, is combined with an antibiotic called tobramycin, it kills the cells that protect the CF bacteria, known as Pseudomonas aeruginosa, by up to 99.9 percent.

CF is a common genetic disease with one in every 2,500 to 3,500 people diagnosed with it at an early age. It results in a thick mucus in the lungs, which becomes a magnet for bacteria.

These bacteria are notoriously difficult to kill because they are protected by a slimy barrier known as a biofilm, which allows the disease to thrive even when treated with antibiotics.

"The problem that we're really tackling is finding ways to kill these biofilms," said Chris Waters, lead author of the study and a microbiology professor.

According to Waters, there are many common biofilm-related infections that people get such as ear infections and swollen, painful gums caused by gingivitis. But more serious, potentially fatal diseases join the ranks of CF including endocarditis, or inflammation of the heart, as well as infections from artificial hip and pacemaker implants.

The research is published in the journal Antimicrobial Agents and Chemotherapy.

Waters and his co-authors, Michael Maiden and Alessandra Hunt, grew 6,000 biofilms in petri dishes, added in tobramycin along with many different compounds, to see what worked better at killing the bacteria. Twenty-five potential compounds were effective, but one stood out.

"It's well known that triclosan, when used by itself, isn't effective at killing Pseudomonas aeruginosa," Hunt said, a post-doctoral associate of microbiology and molecular genetics. "But when I saw it listed as a possible compound to use with tobramycin, I was intrigued. We found triclosan was the one that worked every time."

Triclosan has been used for more than 40 years in soaps, makeup and other commercial products because of its antibacterial properties. Recently, the FDA ruled to limit its use in soaps and hand sanitizers due to insufficient data on its increased effectiveness and concern that it was being overused. Clear evidence has shown, though, that its use in toothpaste is safe and highly effective in fighting gingivitis, and it is still approved for use.

"Limiting its use is the right thing to do," Maiden said, a graduate student in medicine. "The key is to avoid creating resistance to a substance so when it's found in numerous products, the chances of that happening increase."

Tobramycin  (below structure) is currently the most widely used treatment for CF, but it typically doesn't clear the lungs of infection, Waters said. Patients typically inhale the drug, yet find themselves chronically infected their whole lives, eventually needing a lung transplant.

"Most transplants aren't a viable option though for these patients and those who do have a transplant see a 50 percent failure rate within five years," he said. "The other issue is that tobramycin can be toxic itself."

Known side effects from the drug include kidney toxicity and hearing loss.

"Our triclosan finding gives doctors another potential option and allows them to use significantly less of the tobramycin in treatment, potentially reducing its use by 100 times," Hunt said.

Within the next year, Waters and his colleagues will begin testing the effectiveness of the combination therapy on mice with hopes of it heading to a human trial soon after since both drugs are already FDA approved.

Just brushing your teeth with toothpaste that has triclosan won't help to treat lung infections though, Maiden said.

"We're working to get this potential therapy approved so we can provide a new treatment option for CF patients, as well as treat other biofilm infections that are now untreatable. We think this can save lives."

Antimicrobial agent triclosan can rapidly disrupt gut bacterial communities

In continuation of my update on triclosan

A new study suggests that triclosan, an antimicrobial and antifungal agent found in many consumer products ranging from hand soaps to toys and even toothpaste, can rapidly disrupt bacterial communities found in the gut.

The research was published today [May 18] in PLOS ONE by scientists from Oregon State University. It was based on findings made with zebrafish, which researchers believe are an important animal model to help determine possible human biological and health impacts of this antimicrobial compound.

Triclosan was first used as a hospital scrub in the 1970s and now is one of the most common antimicrobial agents in the world, found in shampoos, deodorants, toothpastes, mouth washes, kitchen utensils, cutting boards, toys, bedding, socks and trash bags. It continues to be used in medical settings, and can be easily absorbed through the skin.

"There has been a legacy of concern about exposure to microbial pathogens, which has led to increased use of these antimicrobial products," said Thomas Sharpton, an assistant professor of microbiology and statistics in the OSU Colleges of Science and Agricultural Sciences, and corresponding author on the new study.

"However, there's now a growing awareness of the importance of the bacteria in our gut microbiome for human health, and the overuse of antibiotics that can lead to the rise of 'superbugs.' There are consequences to constantly trying to kill the bacteria in the world around us, aspects we're just beginning to understand."

In the new study, researchers found that triclosan exposure caused rapid changes in both the diversity and composition of the microbiome in the laboratory animals. It's not clear what the implication may be for animal or human health, but scientists believe that compromising of the bacteria in the intestinal tract may contribute to the development or severity of disease.

 triclosan

Some bacteria were more susceptible to the impact of triclosan than others, such as the family Enterobacteriaceae; and others were more resilient, such as the genus Pseudomonas.

"Clearly there may be situations where antibacterial agents are needed," said Christopher Gaulke, lead author on the study and a postdoctoral microbiology researcher in the OSU College of Science.

"However, scientists now have evidence that intestinal bacteria may have metabolic, cardiovascular, autoimmune and neurological impacts, and concerns about overuse of these agents are valid. Cumulative impacts are also possible. We need to do significantly more evaluation of their effects, some of which might be dramatic and long lasting."

The gut-associated microbiome performs vital functions for human health, prevents colonization with pathogens, stimulates the development of the immune system, and produces micronutrients needed by the host. Dysfunction of this microbiome has been associated with human disease, including diabetes, heart disease, arthritis and malnutrition, the scientists pointed out in their study.

Humans are routinely exposed to an array of chemicals, metals, preservatives, microbes and nutrients, some of which may be beneficial, some innocuous, and others harmful, the researchers said. Part of the strength of the present study is developing improved ways, through rapid screening of zebrafish, to more easily determine which compounds may be acceptable and which are toxic, scientists say.

Triclosan has been a concern in part because it is so widely used, and it's also readily absorbed through the skin and gastrointestinal tracts, showing up in urine, feces and breast milk. It also has been associated with endocrine disruption in fish and rats, may act as a liver tumor promoter, and can alter inflammatory responses.

This study showed it was quickly associated with shifts in the microbial community structure and can alter the abundance of specific taxa.

Ingredient (Triclosan) in soap points toward new drugs for Toxoplasmosis !

We know that, Triclosan (see structure)  is an antibacterial ingredient in some soaps, toothpastes, odor-fighting socks, and even computer keyboards. Now researchers lead by Dr. Rima McLeod from The University of Chicago, have come up with interesting findings about this drug, i.e., triclosan's molecular structure can be used as  the model for developing other potential medications for toxoplasmosis. 

In the study, Rima McLeod and colleagues point out that toxoplasmosis is one of the world's most common parasitic infections (spread by the parasite Toxoplasma gondii,  T. gondii), from contact with feces from infected cats, eating raw or undercooked meat, and in other ways. Many have no symptoms because their immune systems keep the infection under control and the parasite remains inactive. But it can cause eye damage and other problems, even becoming life threatening in individuals with immune systems weakened by certain medications and diseases like HIV infection, which allow the parasite to become active again, and in some persons without immune compromise. Most current treatments have some potentially harmful side effects and none of them attack the parasite in its inactive stage.

The scientists knew from past research that triclosan has a powerful effect in blocking the action of a key enzyme that T. gondii uses to live. As per the claim by the researchers, Triclosan, however, cannot be used as a medication because it does not dissolve in the blood, how ever  one can use triclosan's molecular structure as the model for developing other potential medications, including some that show promise as more effective treatments for the disease.  Hope this research will lead to a better drug than Triclosan without any carcinogenecity and many other side effects associated with this drug..

Ref : http://pubs.acs.org/stoken/presspac/presspac/abs/10.1021/jm9017724