How an Antibiotic for Acne May Treat Clinically Isolated Syndrome

It's still too early to tell, but an interesting therapy may be on the horizon

An Antibiotic for MS May Help Prevent MS
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A Canadian study published in the New England Journal of Medicine suggests that people with clinically isolated syndrome to multiple sclerosis (called CIS) who take the antibiotic minocycline may have a lower risk of developing full-blown multiple sclerosis.

Certainly, there is a great appeal to taking minocycline as a therapy for CIS, as it's inexpensive, easy to take (it's an oral medication), and has a reasonably good safety profile.

Still, how does it compare to other disease-modifying treatments like Betaseron or Avonex? In addition, the study showing its effectiveness is small, so larger trials are needed to truly determine its benefit.

Let's take a closer look at this potentially emerging therapy. While it may or may not work out, grasping the "why" behind how an antibiotic could possibly prevent the development of MS is fascinating in its own right.

Minocycline as a Potential Treatment for CIS

Before taking a peek into the study behind minocycline as a therapy for CIS, it's important to understand what clinically isolated syndrome to MS is, and how minocycline could even be considered as a potential therapy.

What Is Clinically Isolated Syndrome?

Clinically isolated syndrome to multiple sclerosis, or CIS, refers to people who experience "MS-like" symptoms for at least 24 hours, and these symptoms may or may not correlate with lesions seen on an MRI.

The kicker is that besides this first episode, there are no other clues that a person had any previous MS relapses, either by their history or by their MRI (there are no other MS-related brain lesions).

In other words, a person simply doesn't have enough clinical or radiographic evidence to receive a diagnosis of MS.

Another challenge with diagnosing CIS is that a doctor must confirm that a person's "MS-like" symptoms (for example, optic neuritis) are indeed due to a loss of myelin—the protective covering over nerve cells in the brain and spinal cord.

This may require further testing like a lumbar puncture or evoked potentials, as well as ruling out other MS-mimicking conditions like infection or other autoimmune diseases (for example, systemic lupus erythematosus).

This is where things can get tricky, as a neurologist has to use his or her judgment to determine whether a person with a clinically isolated syndrome to MS should undergo treatment with a disease-modifying therapy.

Usually, treatment is recommended if a person with CIS has an MRI that depicts lesions classically seen in MS.

What Is Minocycline?

Minocycline is an antibiotic, so it's a medication used to prevent the growth of bacteria. It's used to treat a number of medical conditions like acne, or lung, genital, and skin infections.

You may wonder how taking minocycline could possibly benefit someone at risk for developing MS. Well, scientists have found minocycline to have anti-inflammatory properties, so it may calm a person's immune system, in addition to preventing the spread of bacteria.

It's possible that the anti-inflammatory property of minocycline stems from its ability to alter the bacteria in a person's gut since these bacteria play a key role in regulating a person's immune system.

Minocycline is also believed to prevent the migration of certain immune system cells that attack myelin into the brain and spinal cord.

Finally, research suggests that minocycline can protect nerve cells by preventing their death. This is another mechanism through which it may benefit those with CIS.

What Did the Study Reveal?

Over the course of 4 years, 142 participants with CIS from 12 different Canadian MS clinics were randomly assigned to receive either 100mg of minocycline twice a day or a placebo.

All of the participants had experienced their first CIS-related symptoms within 180 days prior to beginning the study. The majority of the participants were women (68 percent), and this is typical of CIS (it's more common in women), with the average age being approximately 36 years.

The study was double-blind, meaning neither the participants nor the investigators knew whether they were receiving minocycline or placebo.

The participants kept taking the medication (or placebo) until either they were diagnosed with MS or until 24 months after they first began taking minocycline (or placebo).

Results revealed that within 6 months after the participants began taking minocycline, 33 percent developed MS, compared to 61 percent of the participants taking the placebo. This is a whopping difference of nearly 28 percentage points.

After adjusting for the number of baseline MS lesions, the difference went down to 18.5 percent, which is still quite compelling. The reason for this adjustment is that the criteria for diagnosing MS was revised during the course of this study. According to the revised 2010 McDonald criteria, a person could be diagnosed with MS if they have MRI evidence of MS brain lesions, even if they had no symptoms related to those lesions.

While the risk of converting from CIS to MS was significantly lower in those who took minocycline at 6 months as compared to placebo, unfortunately, this was not sustained at 24 months.

How Does Minocycline Compare to Other Therapies for CIS?

The results of this study are similar to other treatments used for CIS like Betaseron (interferon beta-1b), Avonex (interferon beta-1a), and Aubagio (teriflunomide), meaning at 6 months, these therapies all showed similar lower risks for developing MS.

However, there is no head to head trial examining minocycline to one of the above therapies, so it's still too early to tell how it truly compares.

All in all, while minocycline is appealing as a low cost and safe medication, the study examining its benefit as a therapy for CIS was small and had some other study-related limitations.

Larger studies are still needed to deem this a truly worthwhile and effective treatment.

Is There a Downside to Taking Minocycline?

You may be wondering if there is a downside to taking minocycline, like whether or not it is safe or causes any discomfort. This is important because adhering to a twice a day medication can be challenging enough, and if it makes you feel unwell, that adherence becomes even more difficult.

Common side effects that may occur with minocycline include:

  • Diarrhea
  • Dizziness or lightheadedness
  • Headache
  • Dental discoloration (like a graying of the teeth and mouth)
  • Sensitivity to the sun (you can get a worse than normal sunburn)
  • Fungal infections (for example, vaginal yeast infections)

There are also some rare but serious complications that may occur with minocycline like pseudotumor cerebri. In addition, minocycline is contraindicated in pregnancy and nursing, and it may decrease the effectiveness of birth control pills.

However, despite these side effects mentioned, minocycline has an overall good safety profile and people tend to do fine with it.

Of course, like any medication, you need to talk carefully with your doctor about the potential risks of taking minocycline versus its benefit (if it's ever approved for use in CIS), as well as review all of its potential side effects.

A Word From Verywell

While the results of this particular study are exciting, it's simply a baby step in the direction of actually preventing MS from occurring in people who are diagnosed with early symptoms. More studies are needed on minocycline, especially as research is still mixed on the results.

For instance, one study showed minocycline given with Beta-Seron did not improve disease control in people with relapsing-remitting multiple sclerosis. This conflicting research only hints that more research needs to be performed before neurologists begin giving their patients with MS a tetracycline antibiotic.

Sources:

Marcus JF, Waubant EL. Updates on clinically isolated syndrome and diagnostic criteria for multiple sclerosis. Neurohospitalist. 2013 Apr;3(2):65-80.

Metz LM et al. Trial of minocycline in a clinically isolated syndrome of multiple sclerosis. N Eng J Med. 2017 Jun 1;376(22):2122-33.

Multiple Sclerosis Society of Canada. (May 2017). Minocycline for Clinically Isolated Syndrome (CIS) FAQ.

Sørensen PS et al. Minocycline added to subcutaneous interferon β-1a in multiple sclerosis: randomized RECYCLINE study. Eur J Neurol. 2016 May;23(5):861-70.

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