The Role of Taurine in Skeletal Muscle Functioning and Its Potential as a Supportive Treatment for Duchenne Muscular Dystrophy

#apaperaday 

Prof. Annemieke Aartsma-Rus is taking on a challenge by reading and commenting on a paper a day. She shares her insights, findings and thoughts via her @oligogirl Twitter account. See below the overview of March 2022.

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 Prof. Aartsma-Rus reads and comments on the paper titled: The Role of Taurine in Skeletal Muscle Functioning and Its Potential as a Supportive Treatment for Duchenne Muscular Dystrophy

Today’s pick is a review from Merckx and De Paepe from the Multidisciplinary Digital Publishing Institute journal Metabolites. It is a well and clearly written review paper in taurine and its potential role in Duchenne treatment. Doi 10.3390/metabo12020193

You may know taurine from energy drinks. It is an amino acid (AA, formal name 2-aminoethane-sulfonic acid). Taurine plays many roles in the body by itself (not part of proteins). It is obtained through diet (fish & meat), or synthesized from other AA (cysteine or methionine)

The authors focus on the role of taurine in Duchenne, but first outline different processes in skeletal muscle taurine is involved in. In mice with less taurine due to mutations in the taurine transporter (TauT) exercise capacity is reduced, as is strength and survival by 10-20%

So muscle needs taurine. It plays many roles, it regulates osmotic homeostasis (just like electrolytes do but taurine is more inert so there is less risk of unwanted interactions). It also stabilizes membranes, through an as yet unknown mechanism.

Taurine reduces oxidative stress by interacting with HOCl (oxidative stressor), the formed TauCl induces production of antioxidant enzymes. Taurine further facilitates protein production in mitochondria, improves calcium buffering (and thus calcium homeostasis).

As you may know many of the activities of taurine involve processes that are disrupted in Duchenne: there is oxidative stress, membrane fragility, calcium homeostasis is disrupted and there is mitochondria dysfunction.

In dog & humans lacking dystrophin, taurine & TauT levels are increased. In mdx mice, results are less consistent, pointing to a decrease in young & normal levels in older mice. Taurine supplementation has been studied for Duchenne animal models.

Results are not consistent:  in young mdx mice strength increased, but not in older mice. In older (6 mo) *exercised* mice, fatigue resistance was increased. Authors points out lack of robust results may be due to inconsistent dosing, regimen & administration routes.

Duchenne patients are treated with corticosteroids. Combined treatment of prednisone & taurine improved muscle strength in 1 study but not another. Authors outline studies in wild type animals (rats and mice) show only a temporary increase in taurine levels after supplementation.

After chronic dosing, levels return back to normal. Treatment is generally well tolerated but can lead to increased body weight. Authors indicated this as unwanted -however it depends on the cause (increased muscle mass is good, more fat not good, slightly more water retention ?)

Authors discuss that many Duchenne patients use many supplements. For taurine no clinical trials have been done but authors conclude results in mice are promising (I would say they are controversial and contradictory and more studies are needed).

I recommend the review because authors very clearly explain the different roles and processes. However, I do not like the way they end things after outlining results are contradictory for pages on end, to then say they are promising.

Finally my broken record warning about supplements. Do not think they are without risk. Supplements can interact with medicines resulting in side effects or medicines not working. Also supplements can contain trace amounts of toxins. See Duchenne Parent Project NL paper.

Trace amounts of toxins may seem harmless – and it is if you take the suggested amount. However, many people think ‘more is better’ and because supplements are available easily they do not realize that more can do harm (or more harm if they interact with your medicines).

Pictures by Annemieke, used with permission.

About Professor Annemieke Aartsma-Rus

Prof. Dr. Annemieke Aartsma-Rus is a professor of Translational Genetics at the Department of Human Genetics of the Leiden University Medical Center. Since 2013 she has a visiting professorship at the Institute of Genetic Medicine of Newcastle University (UK).

Her work currently focuses on developing antisense-mediated exon skipping as a therapy for Duchenne muscular dystrophy. In addition, in collaborative efforts she aims to bridge the gap between different stakeholders (patients, academics, regulators and industry) involved in drug development for rare diseases.

In 2013 she was elected a member of the junior section of the Dutch Royal Academy of Sciences (KNAW), which consists of what are considered the top 50 scientists in the Netherlands under 45. From 2015 to 2022, she was selected as the most influential scientist in Duchenne muscular dystrophy by Expertscape.

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