Effect of Biodiversity on Our Skin

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1 Effect of Biodiversity on Our Skin Sahar Abdel Moez A. Ismail MD Assiut Faculty of Medicine Department of Dermatology

2 We live at the crossroads of three global megatrends, three tangled consequences of modernity.

3 Urbanization,

4 . The loss of biodiversity

5 The rise in immunesystem problems

6 What are the impact of those changes on our skin health?

7 The skin is composed of 3 layers:

8 Functions of the skin 1. Cosmetic function 2. Protects against mechanical injury. 3. Prevents invasion of the skin by normal skin flora or pathogenic microorganisms. 4. Melanin pigment protects the skin from the harmful effects of ultraviolet radiation.

9 Functions of the skin (cont.) 6. Acts as a two-way barrier to prevent the inward or outward passage of water and electrolytes. 7. Plays a major role in thermoregulation of the human body. 8. Plays an important role in the immunological host defense 9. Nerves in the skin are responsible for the sensations of touch, pain, cold and itch.

10 Micobes and skin The skin is characterized by a multiplicity of habitats, including invaginations, appendages, and various glands and follicles. Such diversity in environment not surprisingly breeds diversity at the level of the microbiome. Moreover, the skin is in constant contact with the outside world. As a result, the bacterial communities are some of the most diverse human microbiomes.

11 Between humidity and hygiene approaches, clothing and everything in the environment that skin microbes are exposed to; the skin has substantially much more variation Three distinct skin micro biomes, each with fairly strong patterns of microbial composition.

12 The oily, sites of the exocrine glands secrete a mixture of lipids called sebum are dominated by Propionibacterium, including P. acnes, which use the skin s lipids to generate short-chain fatty acids that can fight microbial threats.

13 Moist sites such as the axilla, the elbow, below a woman s breasts, or between the toes are frequented by Corynebacterium that alter the behavior human immune cells

14 The dry sites of the body, the flat surfaces of skin like the forearm or leg that are exposed to different environments, are home to Staphylococcus species, in particular, S. epidermidis. it secrete antimicrobial substances that help fight pathogenic invaders

15 The microbial communities that inhabit the skin, perhaps the most diverse of the human body, are suspected to be key players in host defense. New evidence suggests that commensal skin bacteria both directly protect humans from pathogenic invaders and help the immune system maintain that delicate balance between effective protection and damaging inflammation.

16 Effect of urbanization on biodiversity : As we have become more urban and as we have transformed the world, we have also become experts at replacing habitats filled with many species with habitats populated by just a few.

17 We plant inert cement where forests once grew

18 We clean and scrub our houses with antibiotic wipes and antibacterial detergents.

19 We are reducing diversity in our bodies, in exactly the same way that we are reducing it in the world. We manage our own flesh as we manage the earth.

20 We overuse antibiotics to clean out pathogens in our bodies.

21 One can now even buy underpants preloaded with chemicals that clean away the bacteria below the belt!!!!!!!

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23 The uncontacted Yanomami people are thought to have been in relative isolation since their ancient grandparents arrived in South America. Samples for sequencing were taken from the forearm They had the highest bacterial and functional diversity ever reported in a human group.

24 The complete lack of any antibiotics use and high exposure to the wilderness around them contributed to high bacterial diversity. The difference between this diversity and that of a healthy US resident is very significant. This suggests westernisation severely affects human skin microbiome diversity.

25 Effect of loss of biodiversity on our health Half a dozen theories describe the ways in which the loss of a connection to biological richness might cause us to ail. Elements of these theories are at the core of modern ecology. Less biodiverse systems are less resilient and at greater risk of invasion (whether by pathogens or weed) than more diverse systems.

26 Allergies were not part of the story until the early 1980s Epidemiologists began to notice differences between the immune systems of city kids and farm kids. Farm kids were less likely to have allergies.

27 But David Strachan, an epidemiologist at St. George s University of London, had a curious idea, which he called the hygiene hypothesis. immune system bacteria

28 Perhaps urban kids were too distant from microbial nature for their immune systems to develop properly. Farm kids work in the dirt. They touch farm animals. They are exposed to more life, be it cows, chickens, or as Strachan suspected the microbes that cows and chickens harbor. It was a wild, speculative idea. It also increasingly appears to have been right.

29 several studies tested the hygiene hypothesis In Detroit, houses with dogs had more kinds of bacteria than those without. Pregnant women living in those same doggy houses were less likely than women in dogless houses to show evidence of allergy in their umbilical-cord blood In laboratories, mice without skin bacteria failed to develop normal immune systems. Add skin bacteria back, and their defenses were restored.

30 In May 2012, a team of ecologists, allergy specialists, molecular biologists, and immunologists led by Ilkka Hanski announced the results of their study: comparing the allergies of adolescents living in houses surrounded by biodiversity to those of adolescents surrounded by simplicity the modern landscape of cement and grass.

31 They found that those kids who lived in houses surrounded by a greater diversity of life were themselves covered with different kinds of microbes. They were also less likely to show the immunological signs of allergies.

32 It is the opposite of the germ theory of disease. If the germ theory is the idea that the presence of bad species can make you sick. We can get sick because of the absence of good species or even just the absence of the diversity of species.

33 None of these effects is simple.. Yet, as complex as the connections might be, consensus has begun to emerge that some aspect of dirty living is good. Bacteria seem to be part of the useful dirtiness, but which bacteria? Or maybe the question is, how many? Or what mix

34 Is early childhood exposure to environmental microbes all that matters, or does our exposure as adults further enhance the immunoregulatory circuits?

35 No one has offered a very compelling explanation of how the diversity of plants or life in general in backyards alters the composition of bacteria on human skin. It is too early to know the answer. But the bigger question is : how the composition of bacteria on our skin influences our potential to develop allergies.

36 Several options have emerged 1. The world around us needs to be diverse enough for our immune system to gain perspective. The immune. system is our sixth sense 2. The odds of having some beneficial bacteria species in a house increase with certain kinds of microbial diversity

37 3- Finally, a third possibility: Bacteria and fungi compete. Fungi are everywhere in households and, in contrast to bacteria, seem more likely to cause allergies than to prevent them. May be more diverse household bacteria can fight off fungi, winning an invisible war on our behalf.

38 Are Cosmetics a Major Contributor to the Skin Allergy Epidemic? The exposure of normal, western skin to cosmetics, soap, antibiotics and steroids, does appear to have damage the natural microbial environment of humans, especially in the developed world. The damaged skin cause resident bacterial flora to disappear and leads to pathogenic bacterial and fungal growth.

39 Yet, as much as the idea that some of the species around us are beneficial is foreign to doctors, it is an old hat to ecologists The interdependence of species is self-evident; the normal status of life is to be entangled in other lifes. Our conscious minds and progressive societies seem slow to realize this, but our subconscious immune systems may have known it all along.

40 Danté Fenolio once said I could say that biodiversity should be saved for its beauty alone, but there are more practical and perhaps even life-saving reasons

41 There should be a way forward, a way out of our sick and simple chaos. Could we re-wild the places around us, plant a richness of species in our backyards and so raise healthier children covered in more kinds of bacteria?

42 Based on the probiotic therapy for gut, can we develop an ointment to provide the skin with good bacteria? The idea is to put these bacteria in a cream or in a serum and then apply it to your face to reestablish a natural skin community

43 Such probiotic approaches may need to be personalized, As there s a lot of differences between the microbiome on individual skin, it may not be so simple as bottling one type of microbe in a spray that s going to help everyone

44 Our skin is exposed on a daily basis to the external world, and so doesn t have the problem of access to the required microbes that are essential for the correct running of the skin s immune defenses: re-stocking with the correct flora is not an issue.

45 There is something in the environment that is causing these problems, and it is pointless proposing a pro-biotic solution to this crisis (i.e., adding good microbial communities to the skin) if there is something out there which immediately damages it again.

46 Encouraging natural green space

47 Green roofs are another interesting option, and so are food co-operatives, whereby people in towns and cities can grow vegetables for their own use.

48 Make sure young children have all the time and opportunity they want to play out-of-doors, and encourage them to do so. Give them more freedom to play in places with soil and vegetation.

49 Hanski has some further advice for parents who use antibacterial detergents in their homes with no particular reason: STOP!

50 If we don t conserve our biodiversity, then we risk creating an undefeatable obstacle. We will be only left to wonder whether a species we allowed to vanish might have held the key to curing cancer, whether a lost animal contained a chemical that could have treated heart disease. Such examples should remind us that humanity simply cannot afford to turnour very future depends on it. its back on biodiversity.

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