A single injection of IL-7 protects SCID mice from HFD-induced obesity but not from glucose intolerance and WAT inflammation.

<p>(<b>A</b>) Body weight and perigonadal WAT and BAT masses of SCID male mice fed during 15 weeks with SD or HFD (white bars; PBS/SD, hatched bars; IL-7/SD, grey bars; PBS/HFD, black bars; IL-7/HFD); (<b>B</b>) Intraperitoneal glucose tolerance test at 6 weeks of diet feeding (white bars; PBS/SD, hatched bars; IL-7/SD, grey bars; PBS/HFD, black bars; IL-7/HFD); (<b>C</b>) Expression levels of macrophage (Emr1/F4-80, CD68) and inflammation (TNFα, MCP-1, Nos2) markers in perigonadal WAT, after 15 weeks of diet feeding, using real-time quantitative PCR (white bars; PBS/SD, hatched bars; IL-7/SD, grey bars; PBS/HFD, black bars; IL-7/HFD). Data are expressed as means ± SEM of 8 PBS/SD mice, 6 PBS/IL-7 mice, 3 PBS/HFD mice and 9 IL-7/PBS mice. ^#<i>p</i><0.05, ^##<i>p</i><0.01, ^###<i>p</i><0.001, HFD <i>vs</i> SD within the same injection group; ^*<i>p</i><0.05, ^***<i>p</i><0.001, IL-7 injection <i>vs</i> PBS injection in the same diet group.</p

A single injection of IL-7 reduces WAT inflammation during C57BL/6 HFD feeding.

<p>Real-time quantitative PCR analysis of the perigonadal white adipose tissue from C57BL/6 mice after a unique injection with PBS or IL-7, 16 weeks after SD or HFD feeding. (<b>A</b>) Expression levels of macrophages (Emr1/F4-80, CD68) and B-cells (CD19, CD20) markers; and (<b>B</b>) expression levels of inflammatory markers (TNFα, MCP-1 and Nos2). Data are expressed as means ± SEM of 7 to 9 mice per group (white bars; PBS/SD, hatched bars; IL-7/SD, grey bars; PBS/HFD, black bars; IL-7/HFD). ^#<i>p</i><0.05, ^##<i>p</i><0.01, ^###<i>p</i><0.001, HFD <i>vs</i> SD within the same injection group; ^*<i>p</i><0.05, ^**<i>p</i><0.01, ^***<i>p</i><0.001, IL-7 injection <i>vs</i> PBS injection within the same diet group.</p

Reduced white adipose tissue mass and insulin sensitivity in IL-7 overexpressing mice.

<p>(<b>A</b>) Perigonadal WAT mass in transgenic mice and control animals. Results are expressed as mean ± SEM of 7 WT mice (white bars) and 8 Tg IL-7 mice (black bars). (<b>B</b>) Adipocyte diameter distribution of 3 WT (white circles) and 3 Tg IL-7 (black circles). (<b>C</b>) Ratio of total triglycerides to total DNA (in pg/ng). Results are expressed as mean ± SEM of 3 WT mice (white bars) and 5 Tg IL-7 mice (black bars). (<b>D</b>) Glucose tolerance test: Blood samples for glucose level determination were taken from each individual animal. Results are expressed as mean ± SEM of 5 WT (white circles) and 5 Tg IL-7 (black circles). (<b>E</b>) Insulin tolerance test: Glycaemia were individually measured at the indicated times. Data are presented as mean percentage of basal glycemia (t = 0 min) from average value ± SEM from 5 WT (white circles) and 5 Tg IL-7 (black circles). (<b>F & G</b>) <i>In vivo</i> hyperinsulinaemic-euglycaemic clamps were performed using [3-³H] glucose and 2-deoxy-D-[1-¹⁴C] glucose (2DG) for the estimation of whole body glucose fluxes (<b>F</b>) and tissue glucose uptake (<b>G</b>), respectively. The uptake of glucose was determined in one red fiber-type of muscle (<i>Soleus</i>, S), one white fiber-type of muscle (<i>Tibialis anterior</i>, TA), inguinal SCAT, perigonadal WAT, and brown adipose tissue (BAT). Results are expressed as the mean ± SEM of 5 WT (white bars) and 5 Tg IL-7 (black bars). Statistically significant differences between the groups are indicated as <b>^*</b><i>p</i><0.05 and <b>^**</b><i>p</i><0.01.</p

A single injection of IL-7 protects high-fat diet-fed C576BL/6 mice from obesity and glucose intolerance.

<p>(<b>A</b>) Body weight at 16 weeks of diet feeding (white bars; PBS/SD, hatched bars; IL-7/SD, grey bars; PBS/HFD, black bars; IL-7/HFD); (<b>B</b>) An i.p. glucose tolerance test was performed after 5 weeks of diet feeding (grey squares-continuous line; PBS/SD, grey triangles-dotted line; IL-7/SD, black squares-continuous line; PBS/HFD, black triangles-dotted line; IL-7/HFD); (<b>C</b>) Masses of perigonadal WAT, inguinal SCAT and interscapular BAT at 16 weeks of diet feeding (white bars; PBS/SD, hatched bars; IL-7/SD, grey bars; PBS/HFD, black bars; IL-7/HFD); Data are expressed as means ± SEM of 7 to 9 mice per group. ^#<i>p</i><0.05, ^##<i>p</i><0.01, ^###<i>p</i><0.001, HFD <i>vs</i> SD within the same injection group; ^*<i>p</i><0.05, ^**<i>p</i><0.01, IL-7 injection <i>vs</i> PBS injection in the same diet group.</p

The IL-7 receptor is mostly expressed in the stromal vascular fraction of C57BL/6 adipose tissue.

<p>Expression levels of the mRNA of the IL-7 receptor subunits (IL-7Rα; black bars, γ_c; grey bars) (<b>A</b>) and IL-7 (<b>B</b>) in different insulin sensitive tissues and in adipose tissue fractions isolated from three C57BL/6 male mice, using quantitative PCR. The insulin receptor mRNA levels are shown as control (spotted bars). Thymus was used as a positive control for the expression of IL-7 and IL-7R.</p