Introduction of UVB LED application field
With the rising of deep ultraviolet LEDs, UVA and UVC LEDs have gradually replaced traditional mercury lamps and gradually occupy the market. However, for the application field of UVB LED, everyone is still exploring, and it is certain that phototherapy is a new and predictable direction.
Phototherapy is a method of using electromagnetic radiation to generate light of different wavelengths to treat skin diseases [1]. Ultraviolet phototherapy device is the earliest PUVA device. In 1974, scientists such as Parrish et al [2] reported that psoriasis could be cured by irradiating long-wave ultraviolet rays after oral administration of psoralen (Psoralen). The fly in the ointment is that in order to achieve a good therapeutic effect, an auxiliary drug, psoralen, must be used, and the side effects of PUVA therapy are relatively large, which is manifested in the problems of easy skin burns and high risk of cancer during the treatment process. In 1981, scientists such as Parrish[3] showed that 295-313 nm in medium-wave ultraviolet light is the most effective band, UVB below 295 nm has almost no anti-disease activity, and ultraviolet rays greater than 313 nm have a carcinogenic risk. These limitations have driven the clinical use of Narrowband UVB, with 310-313 nm also proven to be the relatively safest band. The emergence of NB UVB therapy solves the problem of needing to use photosensitive compounds such as psoralen, and patients can choose whether to use psoralen, which improves the therapeutic effect and saves the cost of treatment. At present, the instruments for treating skin diseases in hospitals include NB UVB ultraviolet phototherapy apparatus and 308 nm excimer laser therapy apparatus. The latter uses pulsed light waves generated by the noble gas xenon chloride to treat skin diseases. Clinical studies have shown that a single 308 nm wavelength has better therapeutic effects. However, due to the high price and large size, it is not suitable for portable household use. Whether the LED peak wavelength around 308 nm has a better effect remains to be studied.
At present, most of the ultraviolet lamps used are mercury lamps, which generate electromagnetic wave radiation through ionization and excitation of mercury vapor in the mercury lamp. Single wavelength type and easy breakage are typical problems of mercury lamps, and the heavy metal mercury in them is easy to cause serious harm to human body and the environment. On August 16, 2017, the Minamata Convention on Mercury came into effect, and 128 signatories, including China, pledged to reduce the release and use of mercury and protect the public from man-made mercury pollution. Among them, the regulation of handicraft industry means that mercury lamps will be gradually banned. At this time, LEDs came into being due to the advantages of small size, cold light source, energy saving and environmental protection, and no need for preheating (Figure 1). Many companies have been actively deploying UVB LED applications, and a new era of phototherapy is coming. At present, Sanan Optoelectronics has developed a UVB LED with a wavelength peak of 310 nm, and the half-wave width is only 10 nm. The wavelength concentration is more advantageous for the phototherapy effect.
Mr. Yin Dakui, former deputy minister of the Ministry of Health and honorary president of the Chinese Medical Doctor Association, said at the launching ceremony of the “National Dermatology Relief Project China Tour” Shanghai Station that as of 2014, there are about 420 million people in the world suffering from skin diseases, of which , China has nearly 150 million people [5]. Among them, the most common skin diseases are psoriasis (psoriasis), vitiligo, atopic dermatitis, etc. These diseases are characterized by slow healing process, stubbornness and easy repetition. The healing stage requires a lot of energy, manpower and material resources. According to the survey results of the "Dermatological Quality of Life Scale", in addition to the unbearable pain and itching, it is also normal for patients with skin diseases to reduce the quality of social life because they affect their appearance. This shows that not only must a cure be found as soon as possible, but also the mental health of the patient must be paid attention to. It is important to know that mental illness can often destroy a person, and it is possible that a look or a word from others is the last thing that crushes the "camel". straw. Therefore, it is of great significance and imperative to study the pathogenesis and treatment mechanism of skin diseases.
This article aims to explain the pathogenesis and treatment mechanism of psoriasis and vitiligo, which will help patients to understand and understand, to a certain extent, it can reduce the degree of incompatibility and emotional fluctuations of patients in the process of treatment, and improve the safety of patients with skin diseases. Quality of life index.
Vitiligo is an autoimmune disease in which melanin cannot be secreted normally due to the reduction or absence of melanocytes, and the skin lesions are milky white depigmented spots. Its pathogenic mechanism is not yet clear, most scholars believe that autoimmune factors play an important role in the pathogenesis of vitiligo [6]. From the perspective of cell biology, regulatory T cells in patients can not only destroy the immunoregulatory effect of melanocytes, but also the loss of their function will activate cytotoxic T cells, which recognize and fight against melanocytes. antigens, and ultimately destroy melanocytes [7-8]. How Thl7 cells affect autoimmune diseases is also a new research highlight in recent years. In 2005, Harrington et al. [9] first proposed the concept of Thl7 cells. At present, it is believed that CD4+ helper T cells can be divided into four subsets: Th1, Th2, Th17 and regulatory T cells. Thl7 cells can interact with other immune cells by producing a series of cytokines, participate in the process of releasing pro-inflammatory factors, mediate the production of inflammatory responses, and then affect the function of immune cells and the regulation of the immune system.
UVB therapy for vitiligo induces apoptosis of cytotoxic T cells and inhibits the release of pro-inflammatory factors by inhibiting or promoting related cytokines. Scientists such as Imokawa G et al [10] found that the expression of Endothelin-1, Interleukin-1α and Tyrosinase secreted by keratinocytes increased after UVB irradiation. ET-1 is a mitogen of melanocytes, and its increased content promotes the division, proliferation and migration of surviving melanocytes. The role of tyrosinase is to catalyze the formation of melanin by melanocytes. In addition, Yang Xianlu et al. [11] found that UVB can inhibit the expression of IL-17 and IL-23. IL-17 is a cytokine that induces differentiation of Thl7 cells and has a pro-inflammatory effect, while IL-23 indirectly promotes inflammation by up-regulating the secretion of pro-inflammatory factors TNF-α, IL-1β and IL-17. Therefore, UVB regulates the immune balance between regulatory T cells and Th17 cells by inhibiting the release of inflammatory cytokines such as IL-6, IL-17, IL-23, IL-1β, and TNF-α, thereby effectively inhibiting the immune response. [11-12].
Psoriasis, also known as psoriasis, is a chronic autoimmune disease [13]. The patient's immune system is overactive, triggering skin inflammation and causing the epidermal cells to renew faster than normal. The normal epidermal cell renewal cycle is 28-30 days, but due to the faster proliferation of skin epidermal cells, the patient's epidermal cells will be renewed in 3-4 days. As more and more skin cells are rapidly produced, old skin cells are pushed toward the skin's surface, forming scaly erythema (Figure 3).
At present, the pathogenic mechanism of psoriasis is not yet clear. Most scholars believe that UVB induces DNA to produce photopolymers, the most important ones being cyclobutane pyrimidine dimer, 6-4 photoproduct and Dewar isomer, inhibiting epidermal cells. synthesis, which in turn regulates the epidermal cell cycle [14]. UVB can also prolong the cycle of epidermal cells by up-regulating the p53 tumor suppressor gene.
Psoriasis is an autoimmune disease mediated by T cells, and cytokines secreted by T cells affect the immune system and cause severe inflammatory responses. Th1 cells mainly secrete cytokines such as IFN-g, TNF-α, IL-2 and IL-12, which mainly mediate cellular immunity; Th2 cells mainly secrete IL-4, IL-5, IL-10 and IL-13 cells factor, mainly mediating humoral immunity [15]. Th17 is mainly related to cytokines such as IL-17, IL-23 and IL-22. Most scholars believe that the balance between Th1 and Th2 may be the main cause of vitiligo [16], but Li J et al. [17] believe that Th17 plays a more important role in the pathogenesis, and IL-17 in psoriatic skin lesions and IL-22 content was significantly higher than that of normal skin.
In the past few years, the UVB LEDs that can be used in the market are basically monopolized by Japanese and Korean companies, and the country is in its infancy. Based on the excellent performance of Sanan UVC LEDs, Sanan Optoelectronics has now launched a new UVB chip with a wavelength range of 308-320 nm, as well as high-performance packages that can meet the different design needs of customers. Sanan Optoelectronics UVB chip sizes include 20 mil, 30 mil and 42 mil for selection. A single chip can reach an optical power of 40 mW when driven by a current of 350 mA.
For customers who need to achieve high radiation density applications, Sanan can also provide customized packaging services, such as the small near-inorganic 1313 package and the integrated 6868 package with 4 chips, the latter can be driven at a current of 350 mA The optical power can reach 160 mW, and the luminous flux maintenance rate can reach L50 10Khrs at this stage. If this product is used in the field of medical equipment, in order to maintain a good therapeutic effect, the product developer needs to take the therapeutic effective radiation dose as the radiation dose requirement at the end of the product life cycle, so as to estimate and design the initial radiation dose of the product design cycle.
