Fig 1.
DIO mice have enhanced MDSC accumulation in renal tumors and spleens.
(A) Flow cytometry gating strategy for MDSCs. (B) Frequencies of combined monocytic and granulocytic MDSC in tumor-bearing kidneys (TK) and tumor-free contralateral kidneys (CK) over time in DIO and NW mice. (C) Frequencies of combined monocytic and granulocytic MDSC in spleens, livers, and adipose stromal cells (ASC) from tumor-bearing mice in panel B. (D) Relative frequencies of granulocytic to monocytic MDSC are shown for the indicated organs at d14 post-tumor challenge. (B-D) For all, n = 4–8 mice/group, combined from three experiments. Bars indicate mean +/- s.d. Boxes indicate range with mean (horizontal bar). * = p < 0.05.
Fig 2.
Obese mice have elevated concentrations of the MDSC chemoattractant CCL2 in renal tumors.
(A) DIO and NW mice were challenged as in Fig. 1. Tumor-bearing kidneys (TK) or tumor-free contralateral kidneys (CK) were harvested at the times indicated. Homogenates were tested via Multiplex array for CCL2. n = 4–8 mice per group, combined from three experiments. Bars indicate mean +/- sd. * = p < 0.05. (B) Histograms showing intracellular CCL2 for the indicated cell populations. (C) Intracellular CCL2 from pooled DIO versus NW mice for the indicated cell populations, with n = 3–5 mice per group. Bars indicate mean +/- sd. * = p < 0.05.
Fig 3.
Equivalent surface expression of CCR2 on MDSCs from DIO and NW mice.
(A) DIO and NW mice were challenged as in Fig. 1. Tumor-bearing kidneys (TK) or tumor-free contralateral kidneys (CK) were harvested at the times indicated. Histograms show representative surface expression of CCR2 on Ly6C+ or Ly6G+ MDSC from DIO or NW mice. Open histograms = isotype control; shaded histograms = CCR2 staining. (B) Pooled data showing the % of MDSCs that express CCR2 in tumor-bearing kidneys (TK) and contralateral kidneys (CK). Gating on Ly6C+ or Ly6G+ MDSC shows strong and equivalent expression of CCR2 on MDSC subpopulations from DIO and NW mice. (C) Increased overall frequencies of CCR2+ MDSC from both Ly6C+ and Ly6G+ subsets when calculated as a percentage of total live cells within tumor-bearing kidneys. For B and C, n = 4–6 mice per group from two experiments. Bars indicate mean +/- sd. * = p < 0.05.
Fig 4.
Obesity does not alter the suppressive capacity of MDSC.
Tumor-bearing kidneys and spleens from the same mice were harvested between days 21–23. (A) Monocytic (Ly6C+) and granulocytic MDSC (Ly6G+) were sort-purified from each organ, then placed into culture with naive DUC18 T cells and stimulatory splenic DC from tumor-free NW mice. MDSC and stimulatory DC were pulsed with the DUC18 cognate peptide tERK. n = 6–8 mice per group, combined from three experiments. Bars indicate mean +/- sd. * = p < 0.05. TI = tumor-infiltrating: sp = splenic. (B) Bulk tumor and spleen homogenates were surface stained as described in Methods to distinguish monocytic versus granulocytic MDSC subpopulations, then stained intracellularly for arginase-1 expression. Dots indicate results from individual mice. No statistical differences were present in the percentages of arginase+ MDSC subpopulations from like organs in obese versus NW mice.