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Page 10 of 16 Burke. Plast Aesthet Res 2020;7:59 I http://dx.doi.org/10.20517/2347-9264.2020.154

Figure 4. The aryl hydrocarbon receptor (AHR). The AHR is found in the cytoplasm bound to protein chaperone molecules, including
AHR interacting protein, heat shock protein-90, the p53 protein, and the tyrosine kinase oncogene cSRC. When a pollutant ligand
binds to this complex, conformational changes dissemble the complex so that the ligand-AHR unit translocates into the nucleus
where it dimerizes with ARNT. The ligand-AHR-ARNT entity induces transcription of target genes, specific for each xenobiotic ligand.
Overstimulation by the ligand-AHR complex is prevented (1) by RNA transcription of the AHR repressor (AHRR) gene to synthesize co-
repressors; and (2) by cytoplasmic degradation of the ligand-AHR entity after expulsion from the nucleus. After release from the initial
cytoplasmic AHR complex, the chaperone protein oncogene cSRC binds to the epidermal growth factor receptor (EGFR), activating the
cSRC protein kinase to induce carcinogenesis. (Modified from Figure 1 of Vogeley et al. [47] with the author’s consent.). cSRC: “cellular
sarcoma”, photo oncogene tyrosine-protein kinase; ARNT: AHR nuclear translocator

increase in pollution measured. Concentrated soot increased lentigines by 27% on the forehead and 20% on
the cheeks. Women living within 100 m of a busy road showed an increase of 25% and 20% in forehead and
cheeks lentigines, respectively, for each interquartile increase in pollution.

[49]
A further study looked at the VOC NO released by traffic, known to cause lung damage and lung cancer .
2
Facial cheek lentigines were evaluated in women over 50 years old - 806 European Caucasians and 1,072
Chinese, making this the largest study to date of traffic-induced lentigines. Indeed, NO exposure increased
2
lentigines in both cohorts. Lentigines develop at a younger age in Asians despite their cultural avoidance
of sun exposure (in contrast to many Caucasians). This proclivity for lentigines may be due to a particular
genetic marker in the SLC45A2 gene similarly noted in Japanese, a marker known to be involved in
[50]
melanin synthesis .

Indoor pollution
Cigarette smoke is the most significant indoor contaminant; second-hand side-stream smoke permeates
indoor space and is recycled in closed environment; third-hand smoke is carried by the hair, skin, and
[40]
clothes of smokers entering a closed space . In 1969, Henry Daniell recognized that smokers look older
than non-smokers . Several epidemiological papers confirm this observation [52,53,54] . Analysis shows that
[51]
men who smoke have 2.3 times as many wrinkles as nonsmoking males, and women have 3.1 times as