Sex differences in fibrillar collagen composition are linked to subcutaneous adipose tissue expandability and adipocyte precursor proliferation

Figures

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  Fig. 1. Sex differences in subcutaneous adipose tissue fibrillar collagen, metabolic health and remodelling in humans and mice. (a) Representative images and quantification of picrosirius red staining of subcutaneous adipose tissue (SAT) from BMI-matched men and women (n = 10/sex; scale bar, 200 μm; ≥3 images per sample). Correlations between SAT fibrillar collagen content and (b) total cholesterol, (c) HDL cholesterol, (d) LDL cholesterol, (e) ASAT, (f) ALAT and (g) BMI in men and women. (h–r) Male and female C57BL/6 N mice were fed chow or a high-fat diet (HFD) until the HFD-fed groups reached an average body weight > 45 g (n = 6–7/group). Effects of HFD on (h) body weight, (i) SAT weight, (j) oral glucose tolerance and (k) fasting insulin levels. (l) Ratio of pro-inflammatory (M1-like) to anti-inflammatory (M2-like) macrophages. SAT mRNA expression of (m) Ccl2, (n) Col1a1 and (o) Col3a1. (p) SAT adipocyte size distribution. SAT mRNA expression of (q) Lep and (r) Srebp1c. Differences between men and women in (a) were analysed using unpaired Student’s t-test, and associations in (b-g) were analysed using Spearman correlation. Mouse data in h, i, k, l, n, o, q, and r were analysed by…

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  Fig. 2. SAT expansion and fibrillar collagen remodelling in male and female mice during acute HFD challenge. Male and female C57BL/6 N mice were placed on chow or acute HFD for one week (aHFD). Effect of aHFD on (a) body weight and (b) SAT weight. (c) Adipocyte size distribution in SAT of chow and aHFD fed male and female 9-week old mice (n = 4–5/group). Oral glucose tolerance test (d) and fasted insulin levels (e) of chow and aHFD fed male and female mice (n = 4–5/group). (f) Representative image and quantification of picrosirius red staining of male and female chow and aHFD fed SAT (n = 4–5/group). Scale bar 100 μm. At least 3 pictures were taken per sample. (g) Representative images and collagen type 1-to-3 ratio in SAT between chow-fed males and females measured with polarised light microscopy (n = 3–4/group, scale bar 50 μm, at least 3 pictures were taken per sample). (h) SAT Col1a1, Col1a2, and Col3a1 mRNA levels, and (Col1a1 + Col1a2)-to-Col3a1-mRNA ratio in 8-week-old male and female mice (n = 7–8/group). Data are presented as mean ± SEM. The effects of diet and sex in a-f were analysed by two-way ANOVA with Šídák’s multiple-comparisons test (adipocyte size and time as repeated…

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  Fig. 3. Sex differences in SAT proteome and fibrillar collagen composition in mice and humans. (a) Dimensionality reduction with uniform manifold approximation and projection (UMAP). Volcano plots representing the differentially abundant SAT proteins between (b) chow and aHFD females, (c) chow females and males, and (d) aHFD females and males detected and quantified by LC-MS/MS using TMT multiplexing. (e) Heatmap of proteins involved in GO term: stem cell proliferation in (left) chow females vs. chow males and (right) aHFD females vs. aHFD males. Heatmap colour indicates protein abundance. Proteins that are significantly different between the groups are in bold (p < 0.01). (f) (COL1A1 + COL1A2)-to-COL3A1-protein abundance ratio in chow males and females. (COL1A1 + COL1A2)-to-COL3A1-mRNA log2 ratio in human SAT across (g) different age groups and in (h) subjects without obesity and insulin resistance (Lean-IS), with obesity and insulin resistance (Ob-IR), and with obesity and type 2 diabetes (Ob-T2D). (i) (COL1A1 + COL1A2)-to-COL3A1-mRNA log2 ratio in human VAT across different age groups. Data in f-i are presented as mean ± SEM. aHFD; acute HFD for one week, n = 5/group. Multiple…

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  Fig. 4. Stem cell proliferation is increased in female-like gels and female SAT upon aHFD challenge. (a) Gene expression analysis of 3T3-L1 pre-adipocytes seeded in male-like (collagen 1 to 3 ratio 3:1) and female-like (collagen 1 to 3 ratio 1.5:1) collagen gels for 24 h (n = 4–6/group). Data are expressed as relative to male-like gels. (b) Proliferation of 3T3-L1 pre-adipocytes seeded in male- and female-like collagen gels as assessed by %Edu+ cells out of total single live cells (n = 5/group). Two experiments were combined and data are therefore expressed as fold change to male-like collagen gels. Number of total and proliferating CD45−CD31−(Lin−)PDGFRb+ stem cells per gram of SAT in (c) chow and aHFD males and (d) chow and aHFD females (n = 6–7/group). (e) Number of total and proliferating Lin−Sca1+ stem cells per gram of SAT in chow and aHFD females (n = 5–6/group). Number of (f) total and (g) proliferating subsets of Sca1 stem cells per gram of SAT in chow and aHFD females (n = 5–6/group). CD34high = high lipid turnover progenitors; CD34low = low lipid turnover progenitors; CD34neg = beige adipocyte progenitors; aHFD; acute HFD for one week. Data are presented as mean ± SEM.…