Tregs and Hair Growth

In May, two new major hair loss related discoveries received widespread coverage in English language newspapers around the world. Not something you see regularly.

  1. I covered the first of these two in my post on a protein in skin cells called Krox20 that impacts hair growth and pigmentation. This discovery came about accidentally via unrelated research on cancer at University of Texas Southwestern.
  2. The second discovery from the University of California at San Francisco (UCSF) was also accidental. Skin and immune cell related dermatological research led to surprising hair growth findings. This second development is summarized below.

Regulatory T Cells (Tregs)

The latest big development concerns regulatory T Cells (nicknamed “Tregs”) which modulate the immune system. In a new study led by Dr. Michael Rosenblum, it was found that Tregs are directly responsible for triggering stem cells in the skin to promote healthy hair growth. Historically, it was thought that hair growth was entirely related to stem cell activity. The new findings suggest that certain immune cells (i.e., Tregs) are also essential for hair growth and their is some sort of symbiotic communication between immune cells and hair cells.

Increasing Evidence that the Immune System Plays a Role in all Types of Hair Loss

There have been several papers in recent years that have implicated the immune system in hair loss and hair growth. However, in general, scientist continue to believe that immune system defect and inflammation related hair loss only affects 2-3 percent of hair loss sufferers, and they label that type of hair loss as alopecia areata (AA).

For the vast majority (>95 percent) of hair loss sufferers, male hormones (androgens) are causing their hair loss and the condition is therefore labeled as “male pattern baldness (MPB)” or “androgenetic alopecia (AGA)”. The immune system was until recently not thought to play any major role in AGA.

However, famous researcher Dr. Angela Christiano’s findings from Columbia University research in 2014 and 2015 changed all that. Her work implicated the immune system in both AA and AGA (albeit far more clearly in the former). Her team found that certain types of covalently bound topical JAK inhibitors led to hair regrowth in mice suffering from AGA and not just in those suffering from AA. Her AGA related patents were later sold to Aclaris Therapeutics, a company that plans to test topical JAK inhibitors on AGA in future.

Could Tregs also Play a Role in Male Pattern Baldness?

When I first read about this latest study from UCSF, it was in a few UK newspapers and the wording was sometimes a bit unclear when it comes to Tregs and non-alopecia areata type hair loss (e.g., “could also play a role in other types of hair loss”) .

However, later on I read the official UCSF press release article on this, and the below quote right from the horse’s mouth is extremely encouraging:

The new study – published online May 26 in Cell – suggests that defects in Tregs could be responsible for alopecia areata, a common autoimmune disorder that causes hair loss, and could potentially play a role in other forms of baldness, including male pattern baldness, Rosenblum said.

And another version from The Telegraph:

Tregs could also play a role in other forms of baldness, including the classic “male pattern” variety that causes men to recede and lose their hair, the team believes.

Addendum

For many years I have noticed that a large number of people (including myself) suffering from male pattern hair loss seem to also have major regular itching and dandruff episodes. Often requiring daily anti-dandruff shampoo use. In the past, I have mentioned that if JAK inhibitors do ever work to treat AGA, there is a good chance they will work the best on people who have these itching symptom.

I think that immune system attack and inflammation are probably at least partially responsible for the itching and skin flaking. Commentator “Netshed” started an interesting survey in the last post related to scalp itching, and he is welcome to re-post it here. I might do an official survey like that in future too.

Lasers, Wavelength and Hair Growth

I have covered lasers and hair growth on this blog a number of times in the past. A spate of new studies on this subject suggest an emphasis on laser light wavelength during treatment.

New Low Level Laser Therapy Hair Studies

When people discuss laser treatments for hair loss, low-level laser therapy (LLLT) is usually what they mean. There have been many studies done in the past that show LLLT to be beneficial towards scalp hair growth. However, a large number of those studies have been of subpar quality (e.g., small sample size, bad photos) or biased (e.g., sponsored by a laser device manufacturer).

So this subject remains somewhat controversial. However, in the past month, three new studies have been published in support of low level laser therapy to treat hair loss:

  • A 2017 study from China concluded that low level laser therapy stimulates hair growth in mice via upregulating the expression of Wnt10b and β-catenin. Hair follicle count remained the same in LLLT treated mice versus untreated mice, but hair length increased in the former. If this holds true in humans, perhaps LLLT can really make existing hair stronger and less likely to die from the attack by dihydrotestosterone (or at least prolong the battle). However, long-lost hair is probably not going to return from LLLT.
  • A 2017 study from Iran tested a new laser scanner device (with a combination 655 nm red laser plus 808 nm infrared laser) by comparing it with a 655 nm red light laser hat. Both products led to hair growth benefits, but the laser scanner was superior. So laser wavelength may make a difference in outcome.
  • A 2017 study from Egypt on female hair loss sufferers found that combination LLLT+Minoxidil 5% treatment led to the better outcomes (measured via Ludwig scale classification and patient satisfaction) in comparison to LLLT only or Minoxidil 5% only treatments.

LLLT Wavelength: Blue Light > Red Light?

A 2017 study via a European collaboration effort found that a UV-free blue light laser (453 nm wavelength) led to hair growth via prolongation of the anagen phase of the hair cycle, but a red light laser (689 nm length) did not do the same. Update: February 2021 — From the same scientists, a new study on blue light, cryptochrome 1 (CRY1) and hair growth.

This result is surprising since most commercially available LLLT laser products (combs, caps, helmets) are of around 650 nm wavelength (i.e., in the red light spectrum). Interestingly, a 2015 study from South Korea found that 830 nm laser was superior to lower wavelength lasers (of 632 nm, 670 nm and 785 nm) when it came to hair growth in rats.

LLLT Light Wavelength
LLLT Laser Wavelength Spectrum.

The above mentioned European study also made an important finding: “We provide the first evidence that OPN2 and OPN3 are expressed in human hair follicles”.

Update: A November 2021 report finds that photobiomodulation response from 660 nm is more durable than that from 980 nm.

Update: A June 2021 report finds that blue light therapy is a promising therapy for patients affected by androgenetic alopecia. Moreover, blue light-emitting diodes seem to darken grey hair in some people.

Combining Fractional CO2 Laser and Hair Growth Factors

I discussed fractional lasers and hair growth in a post in 2015. Now a new study from China finds that a combination treatment using carbon dioxide fractional laser treatment plus growth factors is significantly superior to using growth factors alone.