Traffic Soot May Be Major Cause of Skin Aging

SEOUL, SOUTH KOREA – New evidence indicates that an important cause of extrinsic skin aging is chronic exposure to soot and other airborne particulates generated by motor vehicle exhaust.

A strong epidemiologic association has been established between residing near a busy highway and increased skin wrinkling and pigmented spots, and a plausible biologic mechanism for causality has been established. Thus, exposure to traffic-related airborne particulate matter joins solar ultraviolet radiation and tobacco smoke as the third potentially modifiable major factor identified in extrinsic skin aging, Dr. Jean Krutmann said at the World Congress of Dermatology.

Photo credit: Sergiy Serdyuk/ISTOCKPHOTO.COM

"My first major message is that nanoparticles are present in ambient air and represent a novel threat to human skin," said Dr. Krutmann, professor of dermatology and environmental health medicine at Heinrich Heine University in Düsseldorf, Germany.

He and his coinvestigators have shown that the threat is more than skin deep.

They have previously linked chronic exposure to traffic-related fine particulate polyaromatic hydrocarbons with a diverse group of other major adverse health effects in addition to skin aging.

They have shown that at one end of the life span, such exposure impairs cognitive function in the elderly (Environ. Res. 2009;109:1,004-11); ongoing prospective studies will determine whether this exposure is also involved in the pathogenesis of Alzheimer's disease.

The same landmark German epidemiologic study that linked airborne particle exposure to mild cognitive impairment – the Study on the Influence of Air Pollution on Lung Function, Inflammation, and Aging (SALIA) – has implicated exposure to traffic-related particulate matter with increased risk of type 2 diabetes (Environ. Health Perspect. 2010;118:1,273-9).

SALIA involved close to 5,000 German women who were enrolled in the mid-1980s, when they were on average 55 years old, and who have been followed for 20 years. Participants were drawn from a heavily industrialized area of Germany as well as from low-pollution rural districts.

At the other end of the life span, Dr. Krutmann and his coinvestigators have demonstrated in prospective studies of 3,390 small-town German newborns followed to age 6 years that exposure to traffic-related airborne particulates was related in dose-response fashion to longer duration of eczema (J. Dermatol. Sci. 2009;56:99-105).

How could sooty air pollution due to incomplete combustion be involved in the pathogenesis of neurodegenerative diseases and type 2 diabetes? Animal studies demonstrate that once these fine airborne particles get into the upper respiratory tract, they can move on to the systemic circulation and exert direct inflammatory effects in other organs – including the brain and pancreas, the dermatologist explained.

The skin aging study was conducted in 400 German women aged 70-80 years who were randomly drawn from the SALIA cohort. The extent of their skin aging was assessed by means of the well-validated Score of Intrinsic and Extrinsic Skin Aging (SCINEXA). Air pollution exposure was determined by the distance between a participant’s home and the nearest major roadway with a traffic volume in excess of 10,000 vehicles per day, as well as by measurement of ambient particulate matter less than 10 mcm in diameter at fixed monitoring sites.

Air pollution exposure proved to be related in dose-response fashion to an increase in pigmented spots on the cheeks and forehead, as well as to facial wrinkles (J. Invest. Dermatol. 2010;130:2,719-26).

Dr. Krutmann said that as a nonepidemiologist, he needs to understand the potential biologic mechanism underlying an epidemiologic observation before he can accept it. He and his colleagues have recently developed such persuasive evidence through animal and in vitro human skin studies.

They have shown that the polyaromatic hydrocarbons in traffic soot activate the aryl hydrocarbon receptor (AhR) expressed on keratinocytes and melanocytes. This results in increased matrix metalloproteinase-1 activity, which in turn leads to degradation of collagen in the dermal matrix and thereby to formation of wrinkles. Activation of the AhR also stimulates melanocyte proliferation, which would explain the increased formation of pigmented spots (J. Invest. Dermatol. 2011;131:203-10).

The clinical implication of these findings is that inhibition of the AhR in skin may be a novel strategy for prevention of extrinsic skin aging. Dr. Krutmann disclosed that he is working with Symrise, a German chemical company, to develop AhR antagonists suitable for topical application in cosmetics. One such product, SymHelios 1031, is already in commercial use.

SALIA and the pediatric eczema studies were funded by the German government.

SEOUL, SOUTH KOREA – New evidence indicates that an important cause of extrinsic skin aging is chronic exposure to soot and other airborne particulates generated by motor vehicle exhaust.

A strong epidemiologic association has been established between residing near a busy highway and increased skin wrinkling and pigmented spots, and a plausible biologic mechanism for causality has been established. Thus, exposure to traffic-related airborne particulate matter joins solar ultraviolet radiation and tobacco smoke as the third potentially modifiable major factor identified in extrinsic skin aging, Dr. Jean Krutmann said at the World Congress of Dermatology.

Photo credit: Sergiy Serdyuk/ISTOCKPHOTO.COM

"My first major message is that nanoparticles are present in ambient air and represent a novel threat to human skin," said Dr. Krutmann, professor of dermatology and environmental health medicine at Heinrich Heine University in Düsseldorf, Germany.

He and his coinvestigators have shown that the threat is more than skin deep.

They have previously linked chronic exposure to traffic-related fine particulate polyaromatic hydrocarbons with a diverse group of other major adverse health effects in addition to skin aging.

They have shown that at one end of the life span, such exposure impairs cognitive function in the elderly (Environ. Res. 2009;109:1,004-11); ongoing prospective studies will determine whether this exposure is also involved in the pathogenesis of Alzheimer's disease.

The same landmark German epidemiologic study that linked airborne particle exposure to mild cognitive impairment – the Study on the Influence of Air Pollution on Lung Function, Inflammation, and Aging (SALIA) – has implicated exposure to traffic-related particulate matter with increased risk of type 2 diabetes (Environ. Health Perspect. 2010;118:1,273-9).

SALIA involved close to 5,000 German women who were enrolled in the mid-1980s, when they were on average 55 years old, and who have been followed for 20 years. Participants were drawn from a heavily industrialized area of Germany as well as from low-pollution rural districts.

At the other end of the life span, Dr. Krutmann and his coinvestigators have demonstrated in prospective studies of 3,390 small-town German newborns followed to age 6 years that exposure to traffic-related airborne particulates was related in dose-response fashion to longer duration of eczema (J. Dermatol. Sci. 2009;56:99-105).

How could sooty air pollution due to incomplete combustion be involved in the pathogenesis of neurodegenerative diseases and type 2 diabetes? Animal studies demonstrate that once these fine airborne particles get into the upper respiratory tract, they can move on to the systemic circulation and exert direct inflammatory effects in other organs – including the brain and pancreas, the dermatologist explained.

The skin aging study was conducted in 400 German women aged 70-80 years who were randomly drawn from the SALIA cohort. The extent of their skin aging was assessed by means of the well-validated Score of Intrinsic and Extrinsic Skin Aging (SCINEXA). Air pollution exposure was determined by the distance between a participant’s home and the nearest major roadway with a traffic volume in excess of 10,000 vehicles per day, as well as by measurement of ambient particulate matter less than 10 mcm in diameter at fixed monitoring sites.

Air pollution exposure proved to be related in dose-response fashion to an increase in pigmented spots on the cheeks and forehead, as well as to facial wrinkles (J. Invest. Dermatol. 2010;130:2,719-26).

Dr. Krutmann said that as a nonepidemiologist, he needs to understand the potential biologic mechanism underlying an epidemiologic observation before he can accept it. He and his colleagues have recently developed such persuasive evidence through animal and in vitro human skin studies.

They have shown that the polyaromatic hydrocarbons in traffic soot activate the aryl hydrocarbon receptor (AhR) expressed on keratinocytes and melanocytes. This results in increased matrix metalloproteinase-1 activity, which in turn leads to degradation of collagen in the dermal matrix and thereby to formation of wrinkles. Activation of the AhR also stimulates melanocyte proliferation, which would explain the increased formation of pigmented spots (J. Invest. Dermatol. 2011;131:203-10).

The clinical implication of these findings is that inhibition of the AhR in skin may be a novel strategy for prevention of extrinsic skin aging. Dr. Krutmann disclosed that he is working with Symrise, a German chemical company, to develop AhR antagonists suitable for topical application in cosmetics. One such product, SymHelios 1031, is already in commercial use.

SALIA and the pediatric eczema studies were funded by the German government.

SEOUL, SOUTH KOREA – New evidence indicates that an important cause of extrinsic skin aging is chronic exposure to soot and other airborne particulates generated by motor vehicle exhaust.

A strong epidemiologic association has been established between residing near a busy highway and increased skin wrinkling and pigmented spots, and a plausible biologic mechanism for causality has been established. Thus, exposure to traffic-related airborne particulate matter joins solar ultraviolet radiation and tobacco smoke as the third potentially modifiable major factor identified in extrinsic skin aging, Dr. Jean Krutmann said at the World Congress of Dermatology.

Photo credit: Sergiy Serdyuk/ISTOCKPHOTO.COM

"My first major message is that nanoparticles are present in ambient air and represent a novel threat to human skin," said Dr. Krutmann, professor of dermatology and environmental health medicine at Heinrich Heine University in Düsseldorf, Germany.

He and his coinvestigators have shown that the threat is more than skin deep.

They have previously linked chronic exposure to traffic-related fine particulate polyaromatic hydrocarbons with a diverse group of other major adverse health effects in addition to skin aging.

They have shown that at one end of the life span, such exposure impairs cognitive function in the elderly (Environ. Res. 2009;109:1,004-11); ongoing prospective studies will determine whether this exposure is also involved in the pathogenesis of Alzheimer's disease.

The same landmark German epidemiologic study that linked airborne particle exposure to mild cognitive impairment – the Study on the Influence of Air Pollution on Lung Function, Inflammation, and Aging (SALIA) – has implicated exposure to traffic-related particulate matter with increased risk of type 2 diabetes (Environ. Health Perspect. 2010;118:1,273-9).

SALIA involved close to 5,000 German women who were enrolled in the mid-1980s, when they were on average 55 years old, and who have been followed for 20 years. Participants were drawn from a heavily industrialized area of Germany as well as from low-pollution rural districts.

At the other end of the life span, Dr. Krutmann and his coinvestigators have demonstrated in prospective studies of 3,390 small-town German newborns followed to age 6 years that exposure to traffic-related airborne particulates was related in dose-response fashion to longer duration of eczema (J. Dermatol. Sci. 2009;56:99-105).

How could sooty air pollution due to incomplete combustion be involved in the pathogenesis of neurodegenerative diseases and type 2 diabetes? Animal studies demonstrate that once these fine airborne particles get into the upper respiratory tract, they can move on to the systemic circulation and exert direct inflammatory effects in other organs – including the brain and pancreas, the dermatologist explained.

The skin aging study was conducted in 400 German women aged 70-80 years who were randomly drawn from the SALIA cohort. The extent of their skin aging was assessed by means of the well-validated Score of Intrinsic and Extrinsic Skin Aging (SCINEXA). Air pollution exposure was determined by the distance between a participant’s home and the nearest major roadway with a traffic volume in excess of 10,000 vehicles per day, as well as by measurement of ambient particulate matter less than 10 mcm in diameter at fixed monitoring sites.

Air pollution exposure proved to be related in dose-response fashion to an increase in pigmented spots on the cheeks and forehead, as well as to facial wrinkles (J. Invest. Dermatol. 2010;130:2,719-26).

Dr. Krutmann said that as a nonepidemiologist, he needs to understand the potential biologic mechanism underlying an epidemiologic observation before he can accept it. He and his colleagues have recently developed such persuasive evidence through animal and in vitro human skin studies.

They have shown that the polyaromatic hydrocarbons in traffic soot activate the aryl hydrocarbon receptor (AhR) expressed on keratinocytes and melanocytes. This results in increased matrix metalloproteinase-1 activity, which in turn leads to degradation of collagen in the dermal matrix and thereby to formation of wrinkles. Activation of the AhR also stimulates melanocyte proliferation, which would explain the increased formation of pigmented spots (J. Invest. Dermatol. 2011;131:203-10).

The clinical implication of these findings is that inhibition of the AhR in skin may be a novel strategy for prevention of extrinsic skin aging. Dr. Krutmann disclosed that he is working with Symrise, a German chemical company, to develop AhR antagonists suitable for topical application in cosmetics. One such product, SymHelios 1031, is already in commercial use.

SALIA and the pediatric eczema studies were funded by the German government.