Lifetime prevalence and associated factors of itch with skin conditions: Atopic dermatitis, psoriasis and dry skin in individuals aged over 50

BACKGROUND

Itch, common in dermatological conditions, is often accompanied by psychological distress and reduced quality of life. However, research on the prevalence and associated factors of itch with skin conditions in general populations is limited.

OBJECTIVES

This cross-sectional study aimed to determine the lifetime prevalence of itch with skin conditions and identify its associated factors in middle-aged and elderly individuals.

METHODS

Participants from the Rotterdam Study, a population-based cohort, were interviewed to assess whether they had ever had an itchy skin condition, defining lifetime itch with skin conditions. Over 20 demographic, lifestyle, dermatological, and non-dermatological factors were collected. Multivariable logistic regression analysis explored associations between these factors and itch with skin conditions, reported as odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

5,246 eligible participants (age range: 51-100, median age: 67, female: 56.0%) revealed a lifetime prevalence of 33.7% for itch with skin conditions. Female sex (OR (95% CI): 1.26 (1.11-1.43)), body mass index (1.02 (1.01-1.03)), self-reported and presence of atopic dermatitis (4.29 (3.74-4.92), and 1.97 (1.60-2.43)), self-reported and presence of psoriasis (2.31 (1.77-3.01), and 2.11 (1.55-2.87)), self-reported dry skin (1.95 (1.73-2.29)), self-reported asthma (1.40 (1.08-1.83)), renal impairment (1.45 (1.17-1.79)), and clinically relevant depressive and anxiety symptoms (1.85 (1.52-2.25), and 1.36 (1.11-1.66)) were significantly associated with it.

CONCLUSIONS

This study reveals a substantial one-third lifetime prevalence of itch with skin conditions in individuals aged over 50. Significant associations with diverse lifestyle, demographic, dermatological and, intriguingly, non-dermatological factors including renal impairment, imply additional contributors to itch induction or persistence in individuals with skin conditions.

Younger facial looks are associate with a lower likelihood of several age-related morbidities in the middle-aged to elderly

BACKGROUND

Looking older for one's chronological age is associated with a higher mortality rate. Yet it remains unclear how perceived facial age relates to morbidity and the degree to which facial ageing reflects systemic ageing of the human body.

OBJECTIVES

To investigate the association between ΔPA and age-related morbidities of different organ systems, where ΔPA represents the difference between perceived age (PA) and chronological age.

METHODS

We performed a cross-sectional analysis on data from the Rotterdam Study, a population-based cohort study in the Netherlands. High-resolution facial photographs of 2679 men and women aged 51.5-87.8 years of European descent were used to assess PA. PA was estimated and scored in 5-year categories using these photographs by a panel of men and women who were blinded for chronological age and medical history. A linear mixed model was used to generate the mean PAs. The difference between the mean PA and chronological age was calculated (ΔPA), where a higher (positive) ΔPA means that the person looks younger for their age and a lower (negative) ΔPA that the person looks older. ΔPA was tested as a continuous variable for association with ageing-related morbidities including cardiovascular, pulmonary, ophthalmological, neurocognitive, renal, skeletal and auditory morbidities in separate regression analyses, adjusted for age and sex (model 1) and additionally for body mass index, smoking and sun exposure (model 2).

RESULTS

We observed 5-year higher ΔPA (i.e. looking younger by 5 years for one's age) to be associated with less osteoporosis [odds ratio (OR) 0.76, 95% confidence interval (CI) 0.62-0.93], less chronic obstructive pulmonary disease (OR 0.85, 95% CI 0.77-0.95), less age-related hearing loss (model 2; B = -0.76, 95% CI -1.35 to -0.17) and fewer cataracts (OR 0.84, 95% CI 0.73-0.97), but with better global cognitive functioning (g-factor; model 2; B = 0.07, 95% CI 0.04-0.10).

CONCLUSIONS

PA is associated with multiple morbidities and better cognitive function, suggesting that systemic ageing and cognitive ageing are, to an extent, externally visible in the human face.

Lower polyunsaturated fatty acid levels and FADS2 expression in adult compared to neonatal keratinocytes are associated with FADS2 promotor hypermethylation

Keratinocytes produce lipids that are critical for the skin barrier, however, little is known about the impact of age on fatty acid (FA) biosynthesis in these cells. We have examined the relationship between keratinocyte FA composition, lipid biosynthetic gene expression, gene promoter methylation and age. Expression of elongase (ELOVL6 and 7) and desaturase (FADS1 and 2) genes was lower in adult versus neonatal keratinocytes, and was associated with lower concentrations of n-7, n-9 and n-10 polyunsaturated FA in adult cells. Consistent with these findings, transient FADS2 knockdown in neonatal keratinocytes mimicked the adult keratinocyte FA profile in neonatal cells. Interrogation of methylation levels across the FADS2 locus (53 genomic sites) revealed differential methylation of 15 sites in neonatal versus adult keratinocytes, of which three hypermethylated sites in adult keratinocytes overlapped with a SMARCA4 protein binding site in the FADS2 promoter.

Exploration of Sleep as a Specific Risk Factor for Poor Metabolic and Mental Health: A UK Biobank Study of 84,404 Participants

PURPOSE

Short and long sleep durations have adverse effects on physical and mental health. However, most studies are based on self-reported sleep duration and health status. Therefore, this longitudinal study aims to investigate objectively measured sleep duration and subsequent primary health care records in older adults to investigate the impact of sleep duration and fragmentation on physical and mental health.

METHODS

Data on objective sleep duration were measured using accelerometry. Primary care health records were then obtained from the UK Biobank (n=84,404). Participants (mean age, 62.4 years) were divided into five groups according to their sleep duration derived from the accelerometry data: <5 hours, 5-6 hours, 6-7 hours, 7-8 hours and >8 hours. ICD-10 codes were used for the analysis of primary care data. Wake after sleep onset, activity level during the least active 5 hours and episodes of movement during sleep were analysed as an indication for sleep fragmentation. Binary regression models were adjusted for age, gender and Townsend deprivation score.

RESULTS

A "U-shaped" relationship was found between sleep duration and diseases including diabetes, hypertension and heart disease and depression. Short and long sleep durations and fragmented sleep were associated with increased odds of disease.

CONCLUSION

Six to eight hours of sleep, as well as less fragmented sleep, predicted better long-term metabolic and mental health.

Genetics of facial telangiectasia in the Rotterdam Study: a genome-wide association study and candidate gene approach

BACKGROUND

The severity of facial telangiectasia or red veins is associated with many lifestyle factors. However, the genetic predisposition remains unclear.

OBJECTIVES

We performed a genome-wide association study (GWAS) on facial telangiectasia in the Rotterdam Study (RS) and tested for replication in two independent cohorts. Additionally, a candidate gene approach with known pigmentation genes was performed.

METHODS

Facial telangiectasia were extracted from standardized facial photographs (collected from 2010-2013) of 2842 northwestern European participants (median age 66.9, 56.8% female) from the RS. Our GWAS top hits (P-value <10^-6 ) were tested for replication in 460 elderly women of the SALIA cohort and in 576 additional men and women of the RS. Associations of top single nucleotide polymorphisms (SNPs) with expression quantitative trait loci (eQTL) in various tissues were reviewed (GTEx database) alongside phenotype associations in the UK biobank database. SNP-based associations between known pigmentation genes and facial telangiectasia were tested. Conditional analysis on skin colour was additionally performed.

RESULTS

Our most significant GWAS signal was rs4417318 (P-value 5.38*10^-7 ), an intergenic SNP on chromosome 12 mapping to the SLC16A7 gene. Other suggestive SNPs tagged genes ZNF211, ZSCAN4, ICOS and KCNN3; SNP eQTLs and phenotype associations tagged links to the vascular system. However, the top signals did not pass significance in the two replication cohorts. The pigmentation genes KIAA0930, SLCA45A2 and MC1R, were significantly associated with telangiectasia in a candidate gene approach but not independently of skin colour.

CONCLUSION

In this GWAS on telangiectasia in a northwestern European population, no genome-wide significant SNPs were found, although suggestive signals indicate genes involved in the vascular system might be involved in telangiectasia. Significantly associated pigmentation genes underline the link between skin colour and telangiectasia.

Repeat UVA exposure of human skin fibroblasts induces both a transitionary and recovery DNA methylation response

Aim: UVA radiation drives skin photoaging in the dermis, plausibly via persistent changes to DNA methylation in dermal fibroblasts. Methods: Genome-wide DNA methylation changes after five repeated daily UVA doses were determined at 48 h (transitionary) and 1 week (recovery) post final irradiation. Results: Differential methylation was found at the transitionary time point in active chromatin states near genes that are highly expressed in fibroblasts and are involved in cellular defensive mechanisms; the majority of these methylation differences were restored to control levels after 7 day recovery. At the recovery time point, new differential methylation occurred at repressed regions near developmental genes, normally weakly expressed in fibroblasts. Conclusion: UVA irradiation induces transitionary and recovery-associated DNA methylation responses in fibroblasts with contrasting functional characteristics.

Principal component analysis of seven skin-ageing features identifies three main types of skin ageing

BACKGROUND

The underlying phenotypic correlations between wrinkles, pigmented spots (PS), telangiectasia and other related facial-ageing subphenotypes are not well understood.

OBJECTIVES

To analyse the underlying phenotypic correlation structure between seven features for facial ageing: global wrinkling, perceived age (PA), Griffiths photodamage grading, PS, telangiectasia, actinic keratosis (AK) and keratinocyte cancer (KC).

METHODS

This was a cross-sectional study. Facial photographs and a full-body skin examination were used. We used principal component analysis (PCA) to derive principal components (PCs) of common variation between the features. We performed multivariable linear regressions between age, sex, body mass index, smoking and ultraviolet radiation exposure and the PC scores derived from PCA. We also tested the association between the main PC scores and 140 single-nucleotide polymorphisms (SNPs) previously associated with skin-ageing phenotypes.

RESULTS

We analysed data from 1790 individuals with complete data on seven features of skin ageing. Three main PCs explained 73% of the total variance of the ageing phenotypes: a hypertrophic/wrinkling component (PC1: global wrinkling, PA and Griffiths grading), an atrophic/skin colour component (PC2: PS and telangiectasia) and a cancerous component (PC3: AK and KC). The associations between lifestyle and host factors differed per PC. The strength of SNP associations also differed per component with the most SNP associations found with the atrophic component [e.g. the IRF4 SNP (rs12203592); P-value = 1·84 × 10^-22 ].

CONCLUSIONS

Using a hypothesis-free approach, we identified three major underlying phenotypes associated with extrinsic ageing. Associations between determinants for skin ageing differed in magnitude and direction per component. What's already known about this topic? Facial ageing is a complex phenotype consisting of different features including wrinkles, pigmented changes, telangiectasia and cancerous-related growths; it is not clear how these phenotypes are related to each other and to other phenotypes. A few studies have described two main clinical phenotypes for photoageing, namely hypertrophic ageing and atrophic ageing, which have been based solely on the clinical assessment of photoageing characteristics. What does this study add? We are the first to use epidemiology data to identify three main components associated with photoageing, namely a hypertrophic component (global wrinkling; perceived age; Griffiths grading) and atrophic component (pigmented spots; telangiectasia) and a cancer component (actinic keratosis; keratinocyte cancer). Association analysis showed different effects and direction of environmental determinants and genetic associations with the three components, with the most significant gene variants associations found for the atrophic component.

Senescent human melanocytes drive skin ageing via paracrine telomere dysfunction

Cellular senescence has been shown to contribute to skin ageing. However, the role of melanocytes in the process is understudied. Our data show that melanocytes are the only epidermal cell type to express the senescence marker p16^INK4A during human skin ageing. Aged melanocytes also display additional markers of senescence such as reduced HMGB1 and dysfunctional telomeres, without detectable telomere shortening. Additionally, senescent melanocyte SASP induces telomere dysfunction in paracrine manner and limits proliferation of surrounding cells via activation of CXCR3-dependent mitochondrial ROS. Finally, senescent melanocytes impair basal keratinocyte proliferation and contribute to epidermal atrophy in vitro using 3D human epidermal equivalents. Crucially, clearance of senescent melanocytes using the senolytic drug ABT737 or treatment with mitochondria-targeted antioxidant MitoQ suppressed this effect. In conclusion, our study provides proof-of-concept evidence that senescent melanocytes affect keratinocyte function and act as drivers of human skin ageing.

Basal cell carcinoma genetic susceptibility increases the rate of skin ageing: a Mendelian randomization study

BACKGROUND

Onset of basal cell carcinoma (BCC) is connected to skin ageing, but it is unclear whether higher BCC genetic susceptibility drives skin ageing.

OBJECTIVES

To investigate whether loci increasing genetic susceptibility to BCC also drive multiple features of skin ageing, independently of confounding factors, using Mendelian randomization.

METHODS

A Mendelian randomization study was conducted in older adults from the Leiden Longevity Study (N = 604). A total of 25 BCC loci, selected based on a published genome-wide association study on BCC (P-value < 5 × 10^-8 ), were used as genetic instruments for the calculation of a standardized (mean = 0, SD = 1) weighted BCC genetic risk score. Based on facial photographs, we determined perceived age, and skin wrinkling and pigmented spot grading.

RESULTS

A higher BCC genetic risk score was associated with a higher perceived age (adjusted for chronological age and sex) of 0.88 years (95% CI: 0.44, 1.31; P-value = 7.1e^-5 ), greater wrinkling by 0.14 grades (95% CI: 0.05, 0.23; P-value = 2.3e^-3 ), and greater pigmented spots by 0.17 grades (95% CI: 0.08, 0.25; P-value = 1.1e^-4 ). These findings were weakened but still present after exclusion of gene variants in MC1R and IRF4 which have potential pleiotropic effects.

CONCLUSIONS

Mechanisms influenced by genetic loci increasing susceptibility to BCC also drive skin ageing suggesting shared biology and shared targets for interventions.

Are skin senescence and immunosenescence linked within individuals?

With advancing age, many organs exhibit functional deterioration. The age‐associated accumulation of senescent cells is believed to represent one factor contributing to this phenomenon. While senescent cells are found in several different organ systems, it is not known whether they arise independently in each organ system or whether their prevalence within an individual reflects that individual's intrinsic aging process. To address this question, we studied senescence in two different organ systems in humans, namely skin and T cells in 80 middle‐aged and older individuals from the Leiden Longevity Study. Epidermal p16INK4a positivity was associated with neither CD4⁺ nor CD8⁺ T‐cell immunosenescence phenotype composites (i.e., end‐stage differentiated/senescent T cells, including CD45RA⁺CCR7^‐CD28^‐CD27^‐CD57⁺KLRG1⁺ T cells). Dermal p16INK4a positivity was significantly associated with the CD4⁺, but not with the CD8⁺ immunosenescence composite. We therefore conclude that there is limited evidence for a link between skin senescence and immunosenescence within individuals.

Prevalence and determinants for xerosis cutis in the middle-aged and elderly population: A cross-sectional study

BACKGROUND

Determinants and the extent of dry skin in healthy middle-aged and elderly populations have not been well established.

OBJECTIVE

We aimed to identify the prevalence and determinants for generalized dry skin (GDS) and localized dry skin (LDS) within a large prospective population-based cohort of middle-aged and elderly individuals of the Rotterdam Study.

METHODS

Dry skin was physician-graded as none, localized, or generalized. For GDS and LDS, separate multivariable logistic regression analyses were performed to search for association with participant characteristics, lifestyle factors, environmental factors, several comorbidities, and drug exposure.

RESULTS

Among the 5547 eligible participants, 60% had dry skin, of whom a fifth had GDS. Age, female sex, skin color, body mass index, outside temperature, eczema, and chemotherapy in the past were significant determinants for both GDS and LDS. Smoking, the use of statins and diuretics, poorer self-perceived health, and several dermatologic conditions increased the likelihood of having GDS only. Daily cream use was associated with less LDS.

LIMITATIONS

Interobserver variability and residual confounding could have influenced our results. Because of our cross-sectional design, we could not infer causality.

CONCLUSION

We identified factors significantly associated with dry skin in a general middle-aged and elderly population, with health parameters more strongly associated with GDS.

No Causal Association between 25-Hydroxyvitamin D and Features of Skin Aging: Evidence from a Bidirectional Mendelian Randomization Study

Data from in vitro experiments suggest that vitamin D reduces the rate of skin aging, whereas population studies suggest the opposite, most likely due to confounding by UV exposure. We investigated whether there are causal associations between 25-hydroxyvitamin D concentrations and features of skin aging in a bidirectional Mendelian randomization study. In the Rotterdam Study (N = 3,831; 58.2% women, median age 66.5 years) and Leiden Longevity Study (N = 661; 50.5% women, median age 63.1 years), facial skin aging features (perceived age, wrinkling, pigmented spots) were assessed either manually or digitally. Associations between 25-hydroxyvitamin D and skin aging features were tested by multivariable linear regression. Mendelian randomization analyses were performed using single nucleotide polymorphisms identified from previous genome-wide association studies. After meta-analysis of the two cohorts, we observed that higher serum 25-hydroxyvitamin D was associated with a higher perceived age (P-value = 3.6 × 10^-7), more skin wrinkling (P-value = 2.6 × 10^-16), but not with more pigmented spots (P-value = 0.30). In contrast, a genetically determined 25-hydroxyvitamin D concentration was not associated with any skin aging feature (P-values > 0.05). Furthermore, a genetically determined higher degree of pigmented spots was not associated with higher 25-hydroxyvitamin D (P-values > 0.05). Our study did not indicate that associations between 25-hydroxyvitamin D and features of skin aging are causal.

Lifestyle and Physiological Factors Associated with Facial Wrinkling in Men and Women

Facial wrinkling is one of the most notable signs of skin aging. Men and women show different wrinkling patterns yet the lifestyle and physiological factors underlying these sex-specific patterns are relatively unknown. Here, we investigated sex-specific determinants for facial wrinkles. Wrinkle area was quantified digitally using facial photographs of 3,831 northwestern Europeans (51-98 years, 58% female). Effect estimates from multivariable linear regressions are presented as the percentage difference in the mean value of wrinkle area per unit increase of a determinant (%Δ). Wrinkle area was higher in men (median 4.5%, interquartile range: 2.9-6.3) than in women (3.6%, interquartile range: 2.2-5.6). Age was the strongest determinant, and current smoking (men: 15.5%Δ; women: 30.9%Δ) and lower body mass index (men: 1.7%Δ; women: 1.8%Δ) were also statistically significantly associated with increased wrinkling. Pale skin color showed a protective effect (men: -21.0%Δ; women: -28.5%Δ) and, in men, sunburn tendency was associated with less wrinkling. In women, low educational levels and alcohol use were associated with more wrinkling, whereas female pattern hair loss and a higher free androgen index were associated with less wrinkling. In summary, we validated known and identified additional determinants for wrinkling. Skin aging-reducing strategies should incorporate the sex differences found in this study.

P16INK4a Positive Cells in Human Skin Are Indicative of Local Elastic Fiber Morphology, Facial Wrinkling, and Perceived Age

Senescent cells are more prevalent in aged human skin compared to young, but evidence that senescent cells are linked to other biomarkers of aging is scarce. We counted cells positive for the tumor suppressor and senescence associated protein p16INK4a in sun-protected upper-inner arm skin biopsies from 178 participants (aged 45-81 years) of the Leiden Longevity Study. Local elastic fiber morphology, facial wrinkles, and perceived facial age were compared to tertiles of p16INK4a counts, while adjusting for chronological age and other potential confounders.The numbers of epidermal and dermal p16INK4a positive cells were significantly associated with age-associated elastic fiber morphologic characteristics, such as longer and a greater number of elastic fibers. The p16INK4a positive epidermal cells (identified as primarily melanocytes) were also significantly associated with more facial wrinkles and a higher perceived age. Participants in the lowest tertile of epidermal p16INK4a counts looked 3 years younger than those in the highest tertile, independently of chronological age and elastic fiber morphology.In conclusion, p16INK4a positive cell numbers in sun-protected human arm skin are indicative of both local elastic fiber morphology and the extent of aging visible in the face.

Both low circulating insulin-like growth factor-1 and high-density lipoprotein cholesterol are associated with hair loss in middle-aged women

BACKGROUND

Multiple biomarkers have been associated with hair loss in women, but studies have shown inconsistent results.

OBJECTIVES

We investigated the associations between markers of cardiovascular disease risk (e.g. serum lipid levels and hypertension) and ageing [e.g. 25-hydroxyvitamin D and insulin-like growth factor (IGF)] with hair loss in a population of middle-aged women.

METHODS

In a random subgroup of 323 middle-aged women (mean age 61·5 years) from the Leiden Longevity Study, hair loss was graded by three assessors using the Sinclair scale; women with a mean score > 1·5 were classified as cases with hair loss.

RESULTS

Every 1 SD increase in high-density lipoprotein (HDL) cholesterol was associated with a 0·65-times lower risk [95% confidence interval (CI) 0·46-0·91] of hair loss. For IGF-1 the risk was 0·68 times lower (95% CI 0·48-0·97) per 1 SD increase, independently of the other studied variables. Women with both IGF-1 and HDL cholesterol levels below the medians of the study population had a 3·47-times higher risk (95% CI 1·30-9·25) of having hair loss.

CONCLUSIONS

Low HDL cholesterol and IGF-1 were associated with a higher risk of hair loss in women. However, further studies are required to infer causal relationships.

The MC1R Gene and Youthful Looks

Looking young for one's age has been a desire since time immemorial. This desire is attributable to the belief that appearance reflects health and fecundity. Indeed, perceived age predicts survival [1] and associates with molecular markers of aging such as telomere length [2]. Understanding the underlying molecular biology of perceived age is vital for identifying new aging therapies among other purposes, but studies are lacking thus far. As a first attempt, we performed genome-wide association studies (GWASs) of perceived facial age and wrinkling estimated from digital facial images by analyzing over eight million SNPs in 2,693 elderly Dutch Europeans from the Rotterdam Study. The strongest genetic associations with perceived facial age were found for multiple SNPs in the MC1R gene (p < 1 × 10(-7)). This effect was enhanced for a compound heterozygosity marker constructed from four pre-selected functional MC1R SNPs (p = 2.69 × 10(-12)), which was replicated in 599 Dutch Europeans from the Leiden Longevity Study (p = 0.042) and in 1,173 Europeans of the TwinsUK Study (p = 3 × 10(-3)). Individuals carrying the homozygote MC1R risk haplotype looked on average up to 2 years older than non-carriers. This association was independent of age, sex, skin color, and sun damage (wrinkling, pigmented spots) and persisted through different sun-exposure levels. Hence, a role for MC1R in youthful looks independent of its known melanin synthesis function is suggested. Our study uncovers the first genetic evidence explaining why some people look older for their age and provides new leads for further investigating the biological basis of how old or young people look.

Disentangling the effects of circulating IGF-1, glucose, and cortisol on features of perceived age

Circulatory levels of insulin-like growth factor (IGF-1), glucose, and cortisol have been previously associated with facial aging. However, as these serum measures are related, it is unclear whether their associations with skin aging occur independently from each other. We aimed to investigate whether the associations between serum IGF-1, glucose, and cortisol levels and perceived age/wrinkle grade occur independently of each other and whether these are mediated via skin wrinkling or via other skin aging features. Perceived age and skin wrinkling grade were assessed in a random sample from the Leiden Longevity Study with non-fasted (N = 579) and fasted blood sampling (N = 219). In our study population, a higher non-fasted IGF-1 level was associated with a lower skin wrinkling grade (p value = 0.014) and tended to associate with a lower perceived age (p value = 0.067), which was mediated for approximately 100 % by skin wrinkling. A higher non-fasted glucose level was associated with a higher perceived age (p value = 0.017), which was mediated for 51 % by skin wrinkling grade (p value = 0.112). A higher fasted cortisol level tended to associate with a higher perceived age (p value = 0.116), which was mediated for 29 % by skin wrinkling. Results remained similar when the serum measures were statistically adjusted for each other. Thus, the previously reported serum measures associate independently from each other with skin aging. IGF-1 is predominantly associated with perceived age by skin wrinkling, whereas cortisol and glucose also by other skin aging features.

p38 MAPK activation upregulates proinflammatory pathways in skeletal muscle cells from insulin-resistant type 2 diabetic patients

Skeletal muscle is the key site of peripheral insulin resistance in type 2 diabetes. Insulin-stimulated glucose uptake is decreased in differentiated diabetic cultured myotubes, which is in keeping with a retained genetic/epigenetic defect of insulin action. We investigated differences in gene expression during differentiation between diabetic and control muscle cell cultures. Microarray analysis was performed using skeletal muscle cell cultures established from type 2 diabetic patients with a family history of type 2 diabetes and clinical evidence of marked insulin resistance and nondiabetic control subjects with no family history of diabetes. Genes and pathways upregulated with differentiation in the diabetic cultures, compared with controls, were identified using Gene Spring and Gene Set Enrichment Analysis. Gene sets upregulated in diabetic myotubes were associated predominantly with inflammation. p38 MAPK was identified as a key regulator of the expression of these proinflammatory gene sets, and p38 MAPK activation was found to be increased in the diabetic vs. control myotubes. Although inhibition of p38 MAPK activity decreased cytokine gene expression from the cultured diabetic myotubes significantly, it did not improve insulin-stimulated glucose uptake. Increased cytokine expression driven by increased p38 MAPK activation is a key feature of cultured myotubes derived from insulin-resistant type 2 diabetic patients. p38 MAPK inhibition decreased cytokine expression but did not affect the retained defect of impaired insulin action in the diabetic muscle cells.

Age-related mitochondrial DNA depletion and the impact on pancreatic Beta cell function

Type 2 diabetes is characterised by an age-related decline in insulin secretion. We previously identified a 50% age-related decline in mitochondrial DNA (mtDNA) copy number in isolated human islets. The purpose of this study was to mimic this degree of mtDNA depletion in MIN6 cells to determine whether there is a direct impact on insulin secretion. Transcriptional silencing of mitochondrial transcription factor A, TFAM, decreased mtDNA levels by 40% in MIN6 cells. This level of mtDNA depletion significantly decreased mtDNA gene transcription and translation, resulting in reduced mitochondrial respiratory capacity and ATP production. Glucose-stimulated insulin secretion was impaired following partial mtDNA depletion, but was normalised following treatment with glibenclamide. This confirms that the deficit in the insulin secretory pathway precedes K⁺ channel closure, indicating that the impact of mtDNA depletion is at the level of mitochondrial respiration. In conclusion, partial mtDNA depletion to a degree comparable to that seen in aged human islets impaired mitochondrial function and directly decreased insulin secretion. Using our model of partial mtDNA depletion following targeted gene silencing of TFAM, we have managed to mimic the degree of mtDNA depletion observed in aged human islets, and have shown how this correlates with impaired insulin secretion. We therefore predict that the age-related mtDNA depletion in human islets is not simply a biomarker of the aging process, but will contribute to the age-related risk of type 2 diabetes.

Intrinsic and extrinsic risk factors for sagging eyelids

IMPORTANCE

Sagging eyelids, or dermatochalasis, are a frequent concern in older adults. It is considered a feature of skin aging, but risk factors other than aging are largely unknown.

OBJECTIVE

To study nongenetic and genetic risk factors for sagging eyelids.

DESIGN

Upper eyelid sagging was graded in 4 categories of severity using digital photographs. Dermatochalasis was defined as the eyelid hanging over the eyelashes. Age, sex, skin color, tanning ability, hormonal status in women, current smoking, body mass index, and sun protection behavior were analyzed in a multivariable multinomial logistic regression model. Genetic predisposition was assessed using heritability analysis and a genome-wide association study.

SETTING AND PARTICIPANTS

The study was performed in 2 independent population-based cohorts. The Rotterdam Study included older adults from one district in Rotterdam, the Netherlands, and the UK Adult Twin Registry (TwinsUK) included twins from all over the United Kingdom. Participants were 5578 unrelated Dutch Europeans (mean age, 67.1 years; 44.0% male) from the Rotterdam Study and 2186 twins (mean age, 53.1 years; 10.4% male) from the TwinsUK.

MAIN OUTCOMES AND MEASURES

Sagging eyelid severity levels, ranging from 1 (normal control) to 4 (severe sagging).

RESULTS

Among 5578 individuals from the Rotterdam Study, 17.8% showed dermatochalasis (moderate and severe sagging eyelids). Significant and independent risk factors for sagging eyelids included age, male sex, lighter skin color, and higher body mass index. In addition, current smoking was borderline significantly associated. Heritability of sagging eyelids was estimated to be 61% among 1052 twin pairs from the TwinsUK (15.6% showed dermatochalasis). A meta-analysis of genome-wide association study results from 5578 Rotterdam Study and 1053 TwinsUK participants showed a genome-wide significant recessive protective effect of the C allele of rs11876749 (P = 1.7 × 10(-8)). This variant is located close to TGIF1 (an inducer of transforming growth factor β), which is a known gene associated with skin aging.

CONCLUSIONS AND RELEVANCE

This is the first observational study to date demonstrating that other risk factors (male sex, genetic variants, lighter skin color, high body mass index, and possibly current smoking) in addition to aging are involved in the origin of sagging eyelids.

Gene expression analysis of mTOR pathway: association with human longevity

mTOR signalling is implicated in the development of disease and in lifespan extension in model organisms. This pathway has been associated with human diseases such as diabetes and cancer, but has not been investigated for its impact on longevity per se. Here, we investigated whether transcriptional variation within the mTOR pathway is associated with human longevity using whole-blood samples from the Leiden Longevity Study. This is a unique cohort of Dutch families with extended survival across generations, decreased morbidity and beneficial metabolic profiles in middle-age. By comparing mRNA levels of nonagenarians and middle-aged controls, the mTOR signalling gene set was found to associate with old age (P = 4.6 × 10(-7)). Single gene analysis showed that seven of 40 mTOR pathway genes had a significant differential expression of at least 5%. Of these, the RPTOR (Raptor) gene was found to be differentially expressed also when the offspring of nonagenarians was compared with their spouses, indicating association with familial longevity in middle-age. This association was not explained by variation between the groups in the prevalence of type 2 diabetes and cancer or glucose levels. Thus, the mTOR pathway not only plays a role in the regulation of disease and aging in animal models, but also in human health and longevity.

High serum glucose levels are associated with a higher perceived age

Estimating perceived age by facial photographs is a good estimate of health in elderly populations. Previously, we showed that familial longevity is marked by a more beneficial glucose metabolism already at middle age. As glucose is also related to skin aging, this study aimed to investigate the association between glucose metabolism and perceived age. Perceived age was assessed using facial photographs and non-fasted glucose and insulin were measured in 602 subjects from the Leiden Longevity Study. Non-diabetic subjects (n = 569) were divided in three strata according to their glucose levels, and diabetic subjects (n = 33; as a proxy of long-term hyperglycemic exposure) were included as a fourth stratum. Considered confounding factors were gender, chronological age, current smoking, body mass index, photo-damage score, and insulin levels. Perceived age was increased from 59.6 years (SE = 0.3) in the first stratum to 61.2 years (SE = 0.6) in diabetic subjects (p for trend = 0.002). In non-diabetic subjects only, perceived age was increased from 59.6 years (SE = 0.3) in the first stratum to 60.6 years (SE = 0.3) in the third stratum (p for trend = 0.009). Continuously, perceived age increased 0.40 years (SE = 0.14, p = 0.006) per 1 mmol/L increase in glucose level in non-diabetic subjects. The present study demonstrates that, also among non-diabetic subjects, higher glucose levels are associated with a higher perceived age. Future research should be focused on elucidating possible mechanisms linking glucose levels to perceived age.

Serum insulin-like growth factor 1 and facial ageing: high levels associate with reduced skin wrinkling in a cross-sectional study

BACKGROUND

Insulin-like growth factor (IGF)-1 is a growth factor that can influence fibroblast functioning, with effects including the inhibition of collagenases and the induction of collagen expression.

OBJECTIVES

To assess whether serum IGF-1, IGF-binding protein (IGFBP)3 and the ratio between IGF-1 and IGFBP3, as a measure of IGF-1 bioavailability, are associated with facial ageing and skin wrinkling.

METHODS

From a random sample comprising 617 subjects from the Leiden Longevity Study, perceived age and skin wrinkling were assessed from facial photographs, and IGF-1 and IGFBP3 were measured in serum. The associations were assessed using linear regression models, adjusted for chronological age, sex, body mass index, smoking and sun exposure.

RESULTS

Across tertiles of the ratio of IGF-1 to IGFBP3, and after adjusting for all potential confounding factors, the mean perceived age decreased from 60·6 years in the lowest tertile to 59·5 years in the highest (P = 0·045). Similarly, the mean skin wrinkling grade decreased from 4·8 in the lowest tertile to 4·5 in the highest (P = 0·011). Adding skin wrinkling as a covariate in the analysis between IGF-1 and perceived age diminished this association.

CONCLUSIONS

This study demonstrates that a higher ratio of IGF-1 to IGFBP3 associates with a lower perceived age, via its association with reduced skin wrinkling. Whether high IGF-1 levels actually delay the accumulation of skin wrinkling now needs investigating.

Morphometric skin characteristics dependent on chronological and biological age: the Leiden Longevity Study

The effect of chronological age on skin characteristics is readily visible, and its underlying histological changes have been a field of study for several years. However, the effect of biological age (i.e. a person's rate of ageing compared to their chronological age) on the skin has so far only been studied in facial photographs. Skin biopsies obtained from middle-aged offspring of nonagenarian siblings that are genetically enriched for longevity were compared to their partners who represent the general Dutch population. Though of the same chronological age, the offspring were previously observed to be of a younger biological age than their partners. The biopsies were analysed on several aspects epidermal and elastic fibre morphology. We investigated whether these skin characteristics were dependent on chronological age, familial longevity (the difference between the offspring and partners) and Framingham heart risk scores, adjusted for external stressors. A decreased thickness and flattening of the epidermis as well as an increased amount of elastic fibres in the reticular dermis were observed with chronological age (P < 0.001, P < 0.001 and P = 0.03, respectively), but no effect of familial longevity was found. The Framingham heart risk score was associated with some skin characteristics. A slower rate of skin ageing does not mark offspring from nonagenarian siblings. Epidermal and elastic fibre morphometric characteristics are not a potential marker for familial longevity in middle-aged subjects enriched for familial longevity.

The number of p16INK4a positive cells in human skin reflects biological age

Cellular senescence is a defense mechanism in response to molecular damage which accumulates with aging. Correspondingly, the number of senescent cells has been reported to be greater in older than in younger subjects and furthermore associates with age-related pathologies. Inter-individual differences exist in the rate at which a person ages (biological age). Here, we studied whether younger biological age is related to fewer senescent cells in middle-aged individuals with the propensity for longevity, using p16INK4a as a marker for cellular senescence. We observed that a younger biological age associates with lower levels of p16INK4a positive cells in human skin.

Genome-wide association study identifies a single major locus contributing to survival into old age; the APOE locus revisited

By studying the loci that contribute to human longevity, we aim to identify mechanisms that contribute to healthy aging. To identify such loci, we performed a genome-wide association study (GWAS) comparing 403 unrelated nonagenarians from long-living families included in the Leiden Longevity Study (LLS) and 1670 younger population controls. The strongest candidate SNPs from this GWAS have been analyzed in a meta-analysis of nonagenarian cases from the Rotterdam Study, Leiden 85-plus study, and Danish 1905 cohort. Only one of the 62 prioritized SNPs from the GWAS analysis (P < 1 × 10⁻⁴) showed genome-wide significance with survival into old age in the meta-analysis of 4149 nonagenarian cases and 7582 younger controls [OR = 0.71 (95% CI 0.65–0.77), P = 3.39 × 10⁻¹⁷]. This SNP, rs2075650, is located in TOMM40 at chromosome 19q13.32 close to the apolipoprotein E (APOE) gene. Although there was only moderate linkage disequilibrium between rs2075650 and the ApoE ε4 defining SNP rs429358, we could not find an APOE-independent effect of rs2075650 on longevity, either in cross-sectional or in longitudinal analyses. As expected, rs429358 associated with metabolic phenotypes in the offspring of the nonagenarian cases from the LLS and their partners. In addition, we observed a novel association between this locus and serum levels of IGF-1 in women (P = 0.005). In conclusion, the major locus determining familial longevity up to high age as detected by GWAS was marked by rs2075650, which tags the deleterious effects of the ApoE ε4 allele. No other major longevity locus was found.

Environmental and lifestyle factors associated with perceived facial age in Chinese women

Perceived facial age has been proposed as a biomarker of ageing with 'looking young for one's age' linked to physical and cognitive functioning and to increased survival for Caucasians. We have investigated the environmental and lifestyle factors associated with perceived facial ageing in Chinese women. Facial photographs were collected from 250 Chinese women, aged 25-70 years in Shanghai, China. Perceived facial age was determined and related to chronological age for each participant. Lifestyle and health information was collected by questionnaire. Bivariate analyses (controlling for chronological age) identified and quantified lifestyle variables associated with perceived facial age. Independent predictors of perceived age were identified by multivariate modelling. Factors which significantly associated with looking younger for one's chronological age included greater years of education (p<0.001), fewer household members (p=0.027), menopausal status (p=0.020), frequency of visiting one's doctor (p=0.013), working indoors (p<0.001), spending less time in the sun (p=0.015), moderate levels of physical activity (p=0.004), higher frequency of teeth cleaning (p<0.001) and more frequent use of facial care products: cleanser (p<0.001); moisturiser (p=0.016) or night cream (p=0.016). Overall, 36.5% of the variation in the difference between perceived and chronological age could be explained by a combination of chronological age and 6 independent lifestyle variables. We have thus identified and quantified a number of factors associated with younger appearance in Chinese women. Presentation of these factors in the context of facial appearance could provide significant motivation for the adoption of a range of healthy behaviours at the level of both individuals and populations.

Why some women look young for their age

The desire of many to look young for their age has led to the establishment of a large cosmetics industry. However, the features of appearance that primarily determine how old women look for their age and whether genetic or environmental factors predominately influence such features are largely unknown. We studied the facial appearance of 102 pairs of female Danish twins aged 59 to 81 as well as 162 British females aged 45 to 75. Skin wrinkling, hair graying and lip height were significantly and independently associated with how old the women looked for their age. The appearance of facial sun-damage was also found to be significantly correlated to how old women look for their age and was primarily due to its commonality with the appearance of skin wrinkles. There was also considerable variation in the perceived age data that was unaccounted for. Composite facial images created from women who looked young or old for their age indicated that the structure of subcutaneous tissue was partly responsible. Heritability analyses of the appearance features revealed that perceived age, pigmented age spots, skin wrinkles and the appearance of sun-damage were influenced more or less equally by genetic and environmental factors. Hair graying, recession of hair from the forehead and lip height were influenced mainly by genetic factors whereas environmental factors influenced hair thinning. These findings indicate that women who look young for their age have large lips, avoid sun-exposure and possess genetic factors that protect against the development of gray hair and skin wrinkles. The findings also demonstrate that perceived age is a better biomarker of skin, hair and facial aging than chronological age.

Ageing appearance in China: biophysical profile of facial skin and its relationship to perceived age

BACKGROUND

Perceived age is important to women and is a primary driver for topical product use and facial cosmetic surgery. Changes in facial features and biophysical skin parameters with chronological age and their associations with perceived age have not been described in Asian populations.

OBJECTIVE

To investigate the relationship between biophysical properties of the skin, visual features of skin ageing and perceived facial age in Chinese women.

METHODS

Facial photographs were collected of 250 Chinese women, aged 25-70 years in Shanghai, China. The perceived facial age was determined and related to the chronological age for each participant and to a range of visual assessments of skin appearance and objective biophysical measurements of the skin. The profile of changes in these parameters with age was investigated together with the differences in those parameters for women judged to look younger than their chronological age and those judged to look older than their chronological age.

RESULTS

Large discrepancies in perceived age (up to 29 years) were found in women of the same chronological age. Each objective skin measure and visual assessment parameter had a stronger correlation with perceived age than with chronological age. The strongest relationships to perceived age were for wrinkles and hyperpigmentation. Skin colour, hydration and trans-epidermal water loss (TEWL) had weaker associations with perceived age. Women judged to look older than their chronological age had significantly higher scores than those judged to look younger for coarse wrinkles and hyperpigmentation across all age groups. The appearance differences between these groups were evident in composite facial images of the same average chronological age.

CONCLUSIONS

We have identified the skin attributes which differ with perceived age in Chinese women. Perceived age is a better measure of the biological age of facial skin than is chronological age in this population.

Perceived age as a biomarker of ageing: a clinical methodology

In a previous field-based study, how old one looks for one's age (perceived age) was found to be predictive of mortality in elderly individuals. In conjunction, perceived age is of relevance and interest to the layperson. Here, a clinical methodology for generating perceived age as a biomarker of facial ageing is detailed. The methodology utilises facial photographs of subjects to present images to large numbers of age assessors who are primarily nationals of the country of study origin. In five observational studies in five different countries involving 874 female subjects it was found that subject age and assessor gender, nationality, age and ageing expertise had little effect on the perceived age data generated. However, increasing the numbers of age assessors up to 50 substantially increased the reproducibility of the mean perceived age for an image and a minimum of 10 assessors were required to give reproducible data. This methodology was also compared to a methodology that utilises passport-type photographs of subjects typically taken in field studies. Although the perceived age data from the two types of images were more similar to each other than to chronological age, there was a marked difference between the two sets of data. Therefore, to allow meaningful comparisons across perceived age studies, the same type of image should be used for the generation of perceived age. In conclusion, the methodology detailed here has demonstrated that perceived age can be a reproducible measure when large numbers of adult age assessors are used and can be utilised globally in studies to investigate facial ageing.