Adiponectin deficiency does not affect development and progression of spontaneous colitis in IL-10 knockout mice

Abstract

The goal of this study was to investigate the role of the adipokine adiponectin (APN) in development of spontaneous colitis in IL-10 knockout (KO) mice. To this aim, we generated double IL-10 APN KO mice and compared their disease development to that of single IL-10 KO mice. Both IL-10 KO and double IL-10 APN KO mice spontaneously developed colitis of comparable severity. No significant differences in inflammatory infiltrate or crypt elongation were observed in colonic tissue obtained from IL-10 KO and double IL-10 APN KO mice at either 12 or 20 wk of age. A comparable increase in circulating levels of serum amyloid A and IFN-gamma was observed in IL-10 KO and double IL-10 APN KO mice as disease progressed. In vitro stimulation of lymphocytes from mesenteric lymph nodes with anti-CD3 and anti-CD28 induced a significantly higher production of IL-17 and TNF-alpha in IL-10 KO and double IL-10 APN KO mice compared with their healthy littermates. No significant differences in cytokine production from lymphocytes or colonic mRNA expression of cytokines were observed between IL-10 KO and double IL-10 APN KO mice. Both IL-10 KO and double IL-10 APN KO mice had a similar decrease in body weight and bone mass compared with their respective healthy littermates. Finally, APN deficiency did not lead to development of insulin resistance, either in APN KO or double IL-10 APN KO mice. In conclusion, lack of APN does not play a significant role in the pathogenesis of spontaneous colonic inflammation in the IL-10 KO model.

Fig. 1.

Inflammatory infiltrate, colonic hyperplasia, and serum markers of inflammation. Inflammatory cell infiltration (A) and crypt elongation (B) were evaluated in colonic tissue at week 12 and 20. Levels of serum amyloid A (SAA; C) and IFN-γ (D) were measured in serum at the same time points. E: cellularity of the mesenteric lymph nodes. F: representative histological samples of colonic tissue from the indicated groups. Data are means ± SE. N = 10 for wild-type (WT) and IL-10 knockout (KO) mice and N = 14 for adiponectin (APN) KO and double IL-10 APN KO mice. *P < 0.05, **P < 0.01, and ***P < 0.001 WT vs. IL-10 KO mice and APN KO vs. double IL-10 APN KO mice.

Fig. 2.

Cytokine production by mesenteric lymphocytes and colonic gene expression. Lymphocytes were isolated from MLN of WT, APN KO, IL-10, KO and double IL-10 APN KO mice at 12 and 20 wk and stimulated with anti-CD3 and anti-CD28. Levels of IL-17 (A) and TNF-α (B) were measured in the supernatant. Colonic expression of IL-17 (C) and TNF-α (D) was determined by RT-PCR. Data in C and D are presented as values normalized to GAPDH. Data are means ± SE. N = 10 for A and B and N = 5 for C and D. *P < 0.05, **P < 0.01, and ***P < 0.001 WT vs. IL-10 KO mice and APN KO vs. IL-10 APN KO mice.

Fig. 3.

Body weight and bone mineral content. WT, IL-10 KO, APN KO, and double IL-10 APN KO males (A) and females (B) were weighed weekly starting at age 4 wk. Both male and female IL-10 KO and double IL-10 APN KO mice were significantly smaller than WT and APN KO mice, respectively, at all time points after age 6 wk. C and D: whole-body BMC was evaluated by dual-energy X-ray absorptiometry (DEXA) in males (C) and females (D). Data are means ± SE. N = 18–22 for A and B and N = 7–10 for C and D. ***P < 0.001 WT vs. IL-10 KO mice and APN KO vs. IL-10 APN KO mice.

Fig. 4.

Glucose and insulin levels. Glucose and insulin levels were measured in serum of fasted mice. Data are means ± SE. N = 10 for WT and IL-10 KO mice and N = 14 for APN KO and double APN KO mice. **P < 0.01, and ***P < 0.001 WT vs. IL-10 KO mice and APN KO vs. IL-10 APN KO mice. ^^P < 0.01 12 wk vs. 20 wk of age. ##P < 0.01 IL-10 KO vs. IL-10 APN KO mice.