Narrowband UVB light therapy (phototherapy) can improve psoriasis in patients by decreasing the levels of a protein called MMP-2, which contributes to the pathology of this disease, according to a new study. The researchers also suggest that MMP-2 can be used as a valuable biomarker for this disease.
The study, “Therapy Of Psoriasis With Narrowband Ultraviolet-B Light Influences Plasma Concentrations Of MMP-2 And TIMP-2 In Patients,” was published in the Journal of Therapeutics and Clinical Risk Management.
Several proteins have been identified as molecular players in the development of psoriasis, including a group of proteins called metalloproteinases (MMPs). These proteins are responsible for the integrity of the extracellular matrix, the structure that surrounds and supports cells from the outside.
The activity of MMPs is regulated by another group of proteins, called the tissue inhibitors of metalloproteinases (TIMPs). The imbalance between MMPs and TIMPs may result in the development of pathological conditions due to cleaving of the extracellular matrix and loss of its support to cells. Importantly, the activation of MMPs can be promoted by inflammatory proteins such as those at play in psoriasis.
A possible treatment for psoriasis is narrowband UVB (NBUVB) therapy, which has been shown to improve psoriatic lesions with high satisfaction rates.
“NBUVB phototherapy as the second-line treatment for psoriasis, recommended when the topical therapy fails, is contraindicated or impractical,” the authors wrote. “UVB radiations of wavelength 311 nm may result in the clearance of disease symptoms after just 5-8 weeks.”
To study the role of MMP-2 and its regulator TIMP-2 in psoriasis, as well as investigate whether NBUVB phototherapy could affect the levels of these two proteins, researchers followed 49 psoriatic patients and 40 healthy volunteers. The Psoriasis Area and Severity Index (PASI) was used to define disease progression in patients (with scores between 2 and 30).
All patients underwent a course of NBUVB phototherapy composed of 20 sessions with two or three weekly treatments, with doses of NBUVB increasing with time up to a maximum value.
The team took blood samples from the participants before and after NBUVB to analyze the levels of MMP-2 and TIMP-2.
Psoriatic patients had increased blood levels of both proteins compared to healthy subjects, but only MMP-2 was significantly increased. Also, both proteins increased with PASI score and disease severity.
NBUVB therapy sessions caused a decrease in the concentration of both proteins, but significantly in the case of MMP-2. Researchers noticed that MMP-2 levels dropped quite a bit in patients with moderate disease progression, but not in the mild group after treatment.
“Elevated concentration of MMP-2 during the course of psoriasis eruption and its significant decrease after the clearance of disease symptoms following a successful NBUVB treatment indicate that this enzyme is implicated in the pathogenesis and expansion of the analyzed condition,” the authors concluded. “Consequently, plasma MMP-2 seems to be a good candidate for a biomarker of psoriasis.”