Vitiligo: in vivo and in vitro evidence for epidermal ROS/RNS-mediated regulation / dysregulation

Published on November 4, 2014   37 min
0:00
My topic today is to speak about vitiligo. And I'm going to present some in vivo and in vitro evidence of epidermal Reactive Oxygen Species and Reactive Nitrogen Species-mediated regulation or dysregulation in this disease.
0:15
The vitiligo is affecting, of course, mostly the skin. And since the skin is the largest, outer-most organ of the human body, it has an approximate size of 1.85 to 2 square meter. It's responsible for the protection of our human body against many environmental stress; for example, radicals, chemicals, heat, cold, water, and so on. So I'm going to explain on the next slide how the layers of the skin is actually composed, especially about the epidermal part of the skin.
0:52
The outermost layer is composed of the epidermis and the dermis and subcutis, as seen in this slide here. The majority of the epidermis is constructed of keratinocytes. This is the melanocytes at the basement membrane. One melanocyte is surrounded by 36 keratinocytes and forming the so-called epidermal unit. At the basement membrane, and we have the stratum basale. That's the proliferation zone of the epidermis, followed by the stratum spinosum and then the stratum corneum. And those are the parts we are interested in right now.
1:29
Now our skin color, that what we are born with, we call it the inherited skin color. And then of course, we can also use tanning to adjust the skin color by, for example, solar exposure.
1:44
This slide shows us the four races of men from the time of Sethos I. Very nice to see the different palettes of skin colors. And in the lower part, we see the tyrosinase activity in the skin of those skin colors. Tyrosinase is the enzyme which is the starting of the melanin biosynthesis. And this has been for a long time regarded as the major step in the initiation of pigmentation.
2:13
This slide shows us some de novo melanogenesis in the sun, which contains the immediate tanning, and then, of course, also the delayed tanning. People are laying in the sun. And in the beginning we are initiating tyrosinase activity. And later, we are forming the pigment, which is shown very nicely in the next slide.
2:35
You can see the histology of the human epidermis. And all the dark parts that you can see their cupping the nucleus in the lower membrane and also some little parts in the cells. Those are the melanosomes. And those are the actual real factories which are produced in the melanocytes, and which then are believed to deliver big support on defense against all the radicals of our solar system.
3:05
Now this slide shows us, actually, some clinical pictures of vitiligo. Vitiligo is a loss of the inherited skin and hair color. In other words, you lose your genetic determined skin color. It can affect all races, and it is not particularly visible in dark skin. It is also seen in light skin.
3:30
The burden is enormous, as we can see in the next slide, which shows a picture that was painted by one of my patients. This is basic tanner, "All eyes are looking at me." I think you cannot really express more how terrible this burden is when you see this person in a big bowl and all eyes are staring on her white spots.
3:55
The correct diagnosis of vitiligo can be done by the characteristic fluorescence under Wood's light. Wood's light is a light which is 250 nanometer. And you see in the left slide, in A, the clinical picture of vitiligo, and then the same picture under Wood's light. I'm sure you will agree you can see a fluorescence.
4:16
The slide shows you very useful and differential diagnosis. If you have also white spots, if there's a laser-induced leukoderm. There's no vitiligo. As you can see that, under Wood's light, there's no fluorescence seen. Something which is very often unfortunately not used. It's very often seen still patients referred as vitiligo, and they are definitely no vitiligo. So this is a very easy tool and it should be used when some people have some doubts in the diagnosis of vitiligo. As we saw before, this can detect all parts of the body, as I showed you the clinical pictures, and so it is mostly easy to diagnose, but sometimes it can also be complicated.
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Vitiligo: in vivo and in vitro evidence for epidermal ROS/RNS-mediated regulation / dysregulation

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