Scleroderma is a chronic connective tissue disorder resulting from an overproduction of collagen, an essential structural protein found throughout the body. Collagen is also the core component of scar tissue, and its overproduction leads to the characteristic thickening and hardening of the skin seen in all types of scleroderma.
Scleroderma currently has no cure, but treatments like phototherapy, or light therapy, may be effective at managing the skin symptoms of the disease.
What is phototherapy?
Phototherapy involves exposing the affected skin to light of a particular wavelength.
In scleroderma, one of the most studied and promising forms of phototherapy is UVA1 therapy, which is restricted to light of a narrow band of wavelengths (340–400nm) within the ultraviolet (UV) spectrum.
It is thought that UVA1 therapy works by triggering the production of an enzyme called collagenase or matrix metalloproteinase-1 (MMP-1) in the exposed cells. Collagenase breaks down the bonds between collagen fibers and may reduce the amount of collagen. This may improve the skin lesions in scleroderma, resulting in the skin softening.
UVA1 therapy may also work to reduce collagen production, for example by lowering levels of TGF-beta and other immune proteins that trigger collagen protein formation or fibrosis.
Finally, UVA1 may reduce the damaging immune response seen in scleroderma by depleting immune cells that trigger inflammation and fibrosis.
Other types of phototherapy include broadband UVB, narrowband UVB, UVA, psoralen and UVA (PUVA), and extracorporeal photochemotherapy. However, current evidence suggests that UVA1 therapy has fewer side effects compared to other types, with similar or better levels of efficacy.
Phototherapy in clinical trials for scleroderma
Phototherapy, and UVA1 treatment in particular, has been studied in both localized and systemic scleroderma patients. While few large-scale randomized and controlled trials have investigated its benefits, those that did, tested a wide range of doses and regimens with largely positive results. Some of these are discussed below.
Phototherapy is more commonly used to treat localized scleroderma, such as morphea. The majority of patients given low-to-medium doses (20 to 50 J/cm2) of UVA1 in eight separate studies, summarized in an article published in the American Journal of Translational Research, saw a significant improvement in their skin condition after 20 to 45 irradiations.
For example, a study published in the International Journal of Dermatology in 2011, investigated the safety and efficacy of UVA1 in 35 people with localized scleroderma. Patients received between 30 to 45 doses of UVA1 treatment, and a marked clinical improvement was observed in 29 of them. This included skin softening and a significant reduction in skin thickness.
UVA1 therapy may also help in systemic scleroderma. A small study published in the Journal of the American Academy of Dermatology in 2000 demonstrated the effect of a medium dose (60 J/cm2) of UVA1 daily in four systemic scleroderma patients. All experienced softened skin lesions, as well as improvements in joint mobility, skin temperature, and skin elasticity.
A retrospective study in 83 patients, which included 16 with systemic scleroderma, in the U.S. examined the effect of three different dosing regimens of UVA1 therapy. Results, published in the journal Photodermatology, Photoimmunology & Photomedicine in 2015, suggested that there may be a dose-dependent increase in response, with patients given higher doses experiencing a greater improvement.
The common immediate side effects of phototherapy include pigmentation, redness, dry skin, itching, and polymorphic light eruption (rashes). These are often short-term. Potential long-term side effects of UVA1 therapy are not yet fully understood, but the treatment may be associated with a slightly higher risk of cancer, or premature skin aging.
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