자외선 B조사 후의 인체 각질형성세포 배양상청액이 멜라닌세포의 배양에 미치는 영향 = The Effect of Supernatant from UVB - Irradiated Cultured Keratinocytes on the Growth , Melanin Content , and Tyrosinase Activity of Human Melanocyte자외선 B조사 후의 인체 각질형성세포 배양상청액이 멜라닌세포의 배양에 미치는 영향

국문 초록 (Abstract)

최근 멜라닌세포와 각질형성세포간의 밀접한 관계로 미루어 각질형성세포가 멜라닌세포의 증식과 기능을 조정할 것이라고 일부 추정되고 있다. 즉 각질형성세포가 정상 상태나 염증 상태에서 여러 cytokine을 생산하는 것으로 알려져 있는데, 이중 interleukin(IL)-1 및 IL-6 등이 멜라닌세포의 증식과 기능에 영향을 미친다는 보고가 있다. DeLuca 등은 세포들 사이의 직접적인 접촉이 멜라닌세포의 성장 및 분화에 필수적이라고 주장하였으며 Gordon 등은 각질형성세포의 배양상청액을 멜라닌세표 배양액에 첨가시 멜라닌세포의 증식과 멜라닌(melanin) 합성을 자극한다고 보고한 바 있다.
자외선 조사에 의한 피부 색소침착 반응 중 ultra-violet-B(UVB)에 의한 지연 색소침착은 멜라닌세포의 수와 멜라닌 합성이 증가되고, 멜라닌세포에서 각질형성세포로 멜라닌 색소의 이동이 증가되는 등의 과정에 의해 발생하게 되며, 이러한 색소침착은 인체에 유해한 작용을 일으키는 과도한 자외선을 흡수하고 차단하는 광보호 작용을 나타내게 된다. 그러나 UVB 조사에 의한 멜라닌 합성의 증가 및 각질형성 세포로 멜라닌의 이동을 증가시키는 기전과 조절인자는 아직 확실히 알려져 있지 않다. 현재까지 UVB가 일차적으로 멜라닌세포에 작용하여 멜라닌세포의 수와 멜라닌 합성이 증가됨으로서 색소침착이 야기된다고 생각되어 왔으나, 표피를 구성하는 세포의 대부분이 각질형성세포이고 또 피부색소 형성에 효과적인 UVB는 표피하부에 위치한 멜라닌세포보다는 주로 각질형성세포가 접하게 되므로 자외선 조사시의 색소형성 과정에 각질형성세포가 일차적 역할을 담당할 가능성이 있을 것으로 저자들은 생각하고, UVB를 조사하거나 조사하지 않은 각질형성세포의 배양상청액을 멜라닌세포 배양에 투여한 후 멜라닌세포의 성장과 멜라닌 합성에 미치는 영향을 비교, 관찰함으로서 정상 피부 색조계에 있어 각질형성세포와 멜라닌세포와의 기능적 관계를 규명하고, UVB에 의한 피부 색소 형성에 각질형성세포가 미치는 영향을 알아보고자 본 연구를 시행하였다.

다국어 초록 (Multilingual Abstract)

Background:Melanin pigment palys a major role in the expression of normal human skin color as well as in the photoprotection against ultraviolet damage. Melanin produced in melanocytes is transferred via dendrites to surrounding keratinocytes, and this anatomical relationship is termed as epidermal melanin unit. The rates of pigment synthesis and transfer by me anocytes appear to be influenced by ultraviolet light, though the precise factors regulating human epidermal pigmentation remain unelucidated. It has been reported that keratinocytes in vitro release factors that could modulate melanocyte behavior. Ultraviloet irradiation was also been known to enhance the release of various kinds of cytokine from keratinocytes in vivo and in vitro. Objective:We postulated that keratinocytes rather than melanocytes could play a primary role in UVB-induced pigmentation and keratinocytes, when irradiated with UVB, release substances that could modulate or stimulate melanin synthesis from melanocytes. The fact that keratinocytes are located efficiently for direct sunlight irradiation at the top of melanocytes that they release various biological factors known to stimulate melanin synthesis from melanocytes and that they constitute the majority of epidermal cells supported this possibility. To investigate this possibility, we evaluated the effect of supernatant from UVB-irradiated cultured keratinocytes on the growth, melanin content, and tyrosinase activity of human melanocytes. Methods:Human cultured keratinocytes were irradiated with UVB 30, 60, or 120mJ/㎠) once, and after 24 hours, supernatant of the keratinocytes were collceted and added to a growth medium of melanocytes for 5 days in concentration of 15, 25 or 35%, We observed numeric and morphologic changes as well as melanin content and tyrosinase activity in situ of cultured human melanocytes. Results: 1. When cultured melanocytes were incubated with supernatant of non-irradiated keratinocytes, the number of melanocytes, amount of melanin and tyrosinase activity increased in groups added with 25% or 35% concentration of supernatant. 2. The number of melanocytes incubated with 15% or 25% concen rations of supernatant from cultured kiratinocytes irradiated with UVB increased in both 30 and 60mJ/㎠ of UVB irradiated groups and decreased in 120mJ/㎠ of UVB irradiated groups. 3. The melanin content of melanocytes incubated with 15% concentration supernatant from UVB-irradiated cultured keratimocytes increased in 120mJ/㎠ of UVB irradiated groups and the melanin content of melanocytes incubated with 25% concentration of supernatant from UVB-irradiated cultured keratinocytes increased in 60 and 120mJ/㎠ of UVB irradiated groups. When cultured melanocytes were incubated with 35% supernatant concentration of supernatant from UVB-irrdiated keratinocytes, the melanin content increased in 30mJ/㎠ of UVB irradiated groups. 4. The tyrosinasse activity of melanocytes incubated with 15% concentration of supernatant from UVB-irradiated cultured kerainocytes increased in 120mJ/㎠ of UVB irradiated groups and the tyrosinase activity of melanocytes incubated with 25% concentration of supernatant from UVB-irradiated cultured keratinocytes increased in 60 and 120mJ/㎠ of UVB irradiated groups. When cultured melanocytes were incubated with 35% supernatant concentration of supernatant from UVB-irradiated keratinocytes, the tyrosinase activity increased in 30mJ/㎠ of UVB irradiated groups. Conclusion:The above results suggest that UVB-irradiated keratinocytes release soluble or photoactivated factors which could modulate the growth and melanization of melanocytes, and that keratinocytes play an important or primary role in the regulation of UVB induced pigmentation. (Kor J Dermatol 1994;32(5):809~819)