ALOPECIA AREATA

WHAT IS ALOPECIA AREATA?

Alopecia areata is a type of hair loss that is also known as ‘spot baldness’.  This type of hair loss often appears as several bald spots in the scalp, though hair loss can affect any area of the body.  Alopecia areata often appears in women that are otherwise healthy.  In a few cases, all the hair on the scalp is lost (alopecia totalis) or over the whole body (alopecia universalis).  Onset and remission are generally unpredictable and in rare cases the hair loss is permanent.

Alopecia areata is thought to be an autoimmune condition stemming from collapse in immune competence.  Autoimmune diseases are normally triggered by an infectious agent.  Whilst there is no absolute known cure for the condition, there are several treatments that can reduce onset and lower severity of the condition.

CLINICAL FEATURES OF ALOPECIA AREATA

Women normally notice small bald patches where the hairless patches appear superficially normal and unscarred.  Whilst the patches can take on many different shapes, they normally appear round or oval.  There can be areas that are regrowing and other active areas of hair loss at the same time.

Some patients notice tingling or mild pain in the areas where hair loss is active.  Hairs that have an “exclamation point” appearance are also characteristic of the disease.  These hairs are normally surrounding the bald patches, thinner near the scalp and only 3-5mm in length.  These exclamation hairs are pulled out more easily than unaffected hairs.

CAUSES OF ALOPECIA AREATA

Alopecia areata is an immune mediated disorder stemming from the body mistakenly attacking its own cells.  Scalp biopsies carried out to diagnose the cause of hair loss  often show a large number of T-cells around the base of the follicle. These T-cells cause inflammation that eventually arrests cell growth and leads to the arrest of hair growth.  Several studies have shown an imbalance in T-cell populations with a marked decrease in regulatory T-cells [1-3].

Regulatory T-cells regulate the immune response and prevent the immune response from overreacting to any perceived threats.  A study in 2019 by the National Alopecia Areata Foundation identified a number of regulatory T-cells are preferentially located to hair follicles. They were required for proper hair cycling and hair growth, they looked at novel therapies to enhance regulatory T-cell populations.

For hair to grow normally, the hair must retain its immune privilege and be safe form the actions of the innate or adaptive immune system. There are several contributing factors that determine whether some is likely to suffer from alopecia areata including: genetics, environmental factors, and prior infections.

ALOPECIA AREATA AND INFECTION

Patients with alopecia areata have a higher rate of infection than the general population.  Infections trigger the manifestation of one of one or more autoimmune diseases in an individual and more than one type of autoimmune disease can be associated with the same microorganism.  When a pathogenic microorganism attempts to proliferate in an immune competent human host, the innate immune response will respond initially, and the adaptive immune response will continue the effort.

To cause an infection, pathogens contact their new host via the skin.  The infectious agent must be able to adhere to, colonise or penetrate the outer layer of the skin to reproduce and establish an infection in the host.  At this stage the pathogen should be diminished (destroyed) by the innate immune system defence.  If an infection can establish itself, the adaptive immune response is initiated in lymphoid tissue directly in response to the antigens presented by the innate immune system.

The adaptive immune response is created by the generation of antibody secreting B cells and antigen-specific T cells.  Infectious particles are cleared by antibodies and T cells clear the intracellular traces of particles.  In addition to removing the infectious agent from the host, the adaptive immune system will retain some memory of the pathogen in case of reinfection.  In autoimmune disease, components of the innate immune system are more virulent and the adaptive immune response acts in a less specific way, attacking the body’s own tissue.  Due to this change in immune function, any infection can trigger alopecia areata in compromised individuals.

CAN ALOPECIA AREATA BE TREATED SUCCESSFULLY?

There are several promising therapies for alopecia areata.  Success often depends on the individual and the severity of the disease.

Potential therapies for alopecia great include:

Corticosteroid therapy | Steroid injections have been used to manipulate the inflammatory actions in the scalp for over 50 years.  Studies showed that 71% of patients showed hair regrowth with 3 treatments carried out fortnightly [4] and another study showed 63% of patients experienced hair regrowth after 4 months after receiving monthly injections [5].  The process involves injecting corticosteroids into the hairless regions of the scalp and are usually given by a dermatologist.  This type of treatment is more suited to those who have less than 50% of the scalp affected.

JAK inhibitors | JAK inhibitors such as are often used in inflammatory diseases and another of autoimmune diseases.  They work by modifying the immune response and cell messenger activity.  JAK inhibitors and tyrosine supplementation have been shown to help restore lost hair in alopecia patients.

Nutritional therapy | Zinc supplementation has been shown to be effective in the treatment of alopecia.  Several studies have shown that increasing serum zinc results in hair regrowth in alopecia areata patients.  Zinc and alopecia areata are connected in that zinc modifies the immune response and thus lessens the aggression of T-cells and the inflammatory response around the hair follicle.

Other medications | Prescription medication has shown some success in the treatment of alopecia areata.  Diphencyprone and anthralin has shown modest success in severe cases.

THE FINAL WORD

If you believe you are suffering from alopecia areata, it is important to seek advice.  Alopecia areata can occur by itself or with other autoimmune or inflammatory diseases.  Most patients experience spontaneous relapse; in other words, the condition often goes away by itself.  Whilst the condition may not go away permanently, several treatments can often reduce the severity of the condition.

REFERENCES

1. Regulatory T‐cells in alopecia areata. Journal of cutaneous pathology, 46(9), pp.653-658.
2. T cell subpopulations in alopecia areata. Journal of the American Academy of Dermatology, 11(2), pp.216-223.
3. Alopecia areata: disease characteristics, clinical evaluation, and new perspectives on pathogenesis. Journal of the American Academy of Dermatology, 78(1), pp.1-12.
4. Intralesional treatment of alopecia areata with triamcinolone acetonide by jet injector. Br J Dermatol 1973: 88: 55–59.
5. Intralesional triamcinolone acetonide in alopecia areata amongst 62 Saudi Arabs. East Afr Med J 1994: 71: 674–675