Gender differences in the fluorescence of human skin in young healthy adults

Skin autofluorescence, a measure for accumulation of advanced glycation end products, positively associates with blood neutrophil and monocyte counts in the general population, and particularly in men with prediabetes

BACKGROUND AND AIMS

Previous studies have shown that skin autofluorescence (SAF), measured with an advanced glycation end product (AGE) reader, estimates the accumulation of AGEs in tissues. SAF is predictive of incident type 2 diabetes, cardiovascular disease (CVD), and CV mortality in the general population. Studies in diabetic mice have shown that activation of the receptor for AGEs in hematopoietic progenitor cells increases blood neutrophils and monocytes, impairing atherosclerosis regression. We asked whether SAF is associated with blood neutrophil and monocyte counts in the general population, and whether this was moderated by prediabetes, diabetes, and sex.

METHODS

We examined the associations between SAF and blood neutrophil/monocyte counts in participants of the Lifelines cohort (n = 58,923: n = 24,382 men, and n = 34,541 women), a prospective population-based cohort from the North of the Netherlands, employing multivariable regression analyses.

RESULTS

SAF positively associated with blood neutrophil and monocyte counts in the whole cohort. The positive association between SAF and monocyte, but not neutrophil, counts was moderated by prediabetes and diabetes. Positive associations between SAF and blood neutrophil and monocyte counts were moderated by male sex. Moreover, three-way interaction analyses revealed that the positive associations between SAF and neutrophil and monocyte counts were moderated by prediabetes, but not diabetes, in male sex.

CONCLUSIONS

SAF is positively associated with blood neutrophil and monocyte counts in the general population, especially in men with prediabetes. This may contribute to the increased CV risk in men with prediabetes.

Near-ultraviolet Light Dermoscopy for Identification of Pigmented Skin Tumours

Abstract is missing (Short communication)

Site-specific variations in cutaneous autofluorescence revealed by excitation-emission matrix spectroscopy

BACKGROUND AND PURPOSE

Although cutaneous autofluorescence has been utilized for evaluation of skin conditions, there is a paucity of data on normal human skin autofluorescence and its dependence on anatomical site. The objective of this study is to use excitation-emission matrix spectroscopy to quantify and characterize skin autofluorescence at different body sites.

METHODS

Ten anatomical sites from 30 healthy volunteers were measured with a double-grating excitation-emission matrix spectrofluorometer.

RESULTS

For the 10 body sites evaluated, there were four overall patterns of autofluorescence: skin from the head and neck exhibits high superficial and low bilayer fluorescence; the dorsal forearm and dorsal hand have both low superficial and bilayer fluorescence; the upper inner arm and back have high superficial and intermediate bilayer fluorescence; while the palm and thumbnail have both high superficial and bilayer fluorescence. The corresponding fluorescence excitation-emission peaks for these patterns were as follows: head and neck, 3 peaks at 290-300/330-350, 360-380/460-485, and 380-420/610-630 nm; dorsal forearm and dorsal hand, 2 peaks around 295-300/345-360 and 385-395/460-485 nm; upper inner arm and back, 3 peaks around 295-300/335-355, 335-340/390-410, and 375-390/455-480 nm; palm and thumbnail, 3 peaks around 285-300/345-355, 335-345/390-410, and 365-390/450-480 nm.

CONCLUSION

Cutaneous fluorescence varies in distinct patterns according to anatomical site, due to the component fluorophores present, skin thickness, and the degree of melanization and long term sun exposure. These EEM patterns for normal skin should be accounted for when interpreting fluorescence signals from disease states and can also be used to guide the selection of optimal wavebands when applying this optical modality.

Non-Invasive Fluorescent Monitoring of Ovarian Cancer in an Immunocompetent Mouse Model

Ovarian cancers (OCs) are the most lethal gynaecological malignancy, with high levels of relapse and acquired chemo-resistance. Whilst the tumour⁻immune nexus controls both cancer progression and regression, the lack of an appropriate system to accurately model tumour stage and immune status has hampered the validation of clinically relevant immunotherapies and therapeutic vaccines to date. To address this need, we stably integrated the near-infrared phytochrome iRFP720 at the ROSA26 genomic locus of ID8 mouse OC cells. Intrabursal ovarian implantation into C57BL/6 mice, followed by regular, non-invasive fluorescence imaging, permitted the direct visualization of tumour mass and distribution over the course of progression. Four distinct phases of tumour growth and dissemination were detectable over time that closely mimicked clinical OC progression. Progression-related changes in immune cells also paralleled typical immune profiles observed in human OCs. Specifically, we observed changes in both the CD8+ T cell effector (Teff):regulatory (Treg) ratio, as well as the dendritic cell (DC)-to-myeloid derived suppressor cell (MDSC) ratio over time across multiple immune cell compartments and in peritoneal ascites. Importantly, iRFP720 expression had no detectible influence over immune profiles. This new model permits non-invasive, longitudinal tumour monitoring whilst preserving host⁻tumour immune interactions, and allows for the pre-clinical assessment of immune profiles throughout disease progression as well as the direct visualization of therapeutic responses. This simple fluorescence-based approach provides a useful new tool for the validation of novel immuno-therapeutics against OC.