Examining gene expression in hair follicles may be sufficient to diagnose chronic discoid lupus erythematosus (CDLE), a kind of lupus in the scalp, avoiding invasive and expensive scalp biopsies, a study suggests.
The study, “Plucked hair follicles from patients with chronic discoid lupus erythematosus show a disease-specific molecular signature,” was published in the journal Lupus Science & Medicine.
CDLE is the most common type of cutaneous lupus erythematosus (lupus that affects the skin), which can occur as part of systemic lupus erythematosus (SLE) or on its own. People with CDLE often develop lesions on areas that get a lot of sun, including the face, neck, and scalp.
Diagnosing CDLE usually requires biopsy of a lesion, which is not ideal for a number of reasons. The procedure is invasive, stressful for patients, expensive, and requires processing and analysis before a diagnosis can be made, often leading to weeks between a test and a diagnosis, thus necessitating additional visits to the doctor, which take even more time and resources.
Yet these lesions often occur on the scalp, and hair can usually be removed less invasively than skin. Might hair follicles — the cells that grow hair — yield enough information for the diagnosis of CDLE?
To find out, researchers collected four to five hair follicles from seven people with CDLE, as well as from six people with psoriasis, another inflammatory skin condition, and from five people without any notable skin inflammation.
The follicles were collected by plucking hairs with tweezers; the researchers wrote that collecting this many follicles “takes an experienced person five minutes,” as the clinician must ensure that the whole follicle at the base of the hair is collected, not just the hair itself.
The researchers then analyzed the gene expression of the cells in the follicles — what genes were “turned on,” and to what extent. They initially did this using a microarray, which can measure the expression of thousands of genes simultaneously.
Hair follicles from CDLE lesions had a gene expression signature that was distinct from the signatures of follicles from people with psoriasis or unaffected people. This signature was even distinct from that of hair follicle cells taken from the same CDLE patients in areas without lesions.
Furthermore, the identified signature is similar to what has been found in other studies that looked at gene expression in skin biopsies of lesions from people with CDLE, and the genes in the signature are, according to the researchers, “hallmarks of the immunopathology in CDLE.”
The investigators then double-checked their finding using a different method (qRT-PCR) to more specifically measure the expression of these genes of interest, and the same results were obtained.
These results demonstrate that measuring gene expression in hair follicles as a method for CDLE diagnosis is, at the very least, a plausible strategy.
This is a very small study, and further research will be needed before hair tests of this kind are utilized for routine diagnostics. The researchers also noted that “for diagnostic purposes, it would be highly desirable to measure the identified signature molecules on the protein levels, as this would allow for a higher sample stability, lower costs, and less labor and time-consuming analysis.”