The aim of this study was to detect the expression levels of matrix metalloproteinase (MMP) genes in immortalised human keratinocytes following laser radiation. With the help of real-time quantitative polymerase chain reaction  (qPCR) the content of messenger ribonucleic acid (mRNA) of genes for matrix metalloproteinases (MMP-1, MMP‑2, MMP-9 and MMP-12) was detected. The detection was carried out on HaCaT cells before and after low-intensity laser irradiation with a wavelength of 1270 nm and exposure times of 1 and 5 minutes. It was ascertained that expression of genes for MMP was significantly decreased compared with control samples 2 hours after low-intensity laser irradiation. Expression of genes for MMP-1, MMP-2 and MMP-12 was increased 6 hours after laser irradiation. Expression of genes at 24 hours was multidirectional.

Psoriasis is a chronic inflammatory, recurring, immune-mediated skin disease that involves a number of other organs and systems. It is considered that this pathological process is a result of the effects of genetic factors, exogenous triggers and epigenetic factors1. There are a lot of treatment options available for psoriasis, the less studied of which is laser irradiation as a method of physiotherapy. In the Russian Federation, the intravenous laser irradiation of blood is a widely used method owing to its good results in the treatment of psoriasis. Nevertheless, the mechanism of action remains unknown. In the authors’ research, they tried to explain its possible mechanism according to the effect of laser irradiation on gene expression.

Matrix metalloproteinases

Laser irradiation is a specific type of electromagnetic radiation, which is generated in wavelengths of 100–1000000 nm. It differs from other sources of light because of its coherency, monochromaticity, and sharp focus of the ray.

Matrix metalloproteinases (MMP) are zinc-dependent endopeptidases capable of degrading and remodelling all kinds of extracellular matrix (ECM) and cell membranes. They play a significant role in such processes as skeleton formation, angiogenesis, cell migration, tissue reparation, inflammation and immune response2,3. It has been shown that MMP act in immune response by activation of antibacterial proteins, such as pro-alpha-defensins, and by quick repair of damaged epithelium4. MMP play an important role in the inflammation process owing to their influence on macrophage and lymphocyte  migration, vessel penetrability regulation, and cytokine and chemokine activity regulation5. Psoriasis is an immune-mediated skin disease characterised by increased levels of defensins and inflammatory cytokines. For this reason, MMP are an interesting object for investigation in the case of psoriasis.

MMP-1 is an interstitial collagenase involved in the breakdown of collagen types I, II and III3. MMP-1 is identified in a variety of tissues involved in physiological or pathological remodelling. It is expressed in keratinocytes during wound healing and provides cell migration by binding of the α2β1-integrin with type I collagen. This leads to collagen degradation and remodelling of the ECM6.

MMP-2 and MMP-9 are gelatinases with similar proteolytic activity. MMP-2 and MMP-9 are involved in the breakdown of native collagen (types IV, V, VII, X), fibropectine, osteonectin, laminin, nitronectine, decorine, gelatin, aggrecan, chemokines (CCL 7, CXCL 12), and pro-tumour necrosis factor (TNF)3, 7,8. MMP-2 also break down native collagen types I, II, and III9. However, MMP-2 collagenolytic activity is much less than MMP-110. MMP-2 activates pro-MMP-1 and pro-MMP-9, while MMP-9 activates interleukin-1 (IL-1)-β and transforming growth factor (TGF)-β11,12.

The majority of MMP are not expressed constitutively in vivo. Their expression is induced by exogenous signals such as growth factors (epidermal (EGF), basic fibroblast (BFGF)), cytokines (TNF-α, IL-1), chemical agents, and physical stress. Owing to signal translation pathways, the extracellular stimulus lead to AP-1 transcription factor activation and MMP-1, MMP-9, and MMP-12 binding with it13.

Therefore, it seems reasonable to investigate the activity of genes encoding MMP in human keratinocytes after low-intensity laser irradiation with a wavelength of 1270 nm. In this research, with the help of real-time quantitative polymerase chain reaction (qPCR), the expression levels of genes for MMP-1 -2 -12 in immortalised human keratinocytes after laser irradiation were detected.