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Potential role of regulatory T cells in reversing obesity-linked insulin resistance and diabetic nephropathy.

Eller K, Kirsch A, Wolf AM, Sopper S, Tagwerker A, Stanzl U, Wolf D, Patsch W, Rosenkranz AR, Eller P - Diabetes (2011)

Bottom Line: Obese patients with insulin resistance displayed significantly decreased natural Tregs but an increase in adaptive Tregs in their visceral adipose tissue as compared with lean control subjects.Conversely, adoptive transfer of CD4(+)FoxP3(+) Tregs significantly improved insulin sensitivity and diabetic nephropathy.Accordingly, there was increased mRNA expression of FoxP3 as well as less abundant proinflammatory CD8(+)CD69(+) T cells in visceral adipose tissue and kidneys of Treg-treated animals.

View Article: PubMed Central - PubMed

Affiliation: Clinical Division of Nephrology, Department of Internal Medicine, Medical University Graz, Graz, Austria. kathrin.eller@medunigraz.at

ABSTRACT

Objective: To assess the potential role of FoxP3-expressing regulatory T cells (Tregs) in reversing obesity-linked insulin resistance and diabetic nephropathy in rodent models and humans.

Research design and methods: To characterize the role of Tregs in insulin resistance, human visceral adipose tissue was first evaluated for Treg infiltration and second, the db/db mouse model was evaluated.

Results: Obese patients with insulin resistance displayed significantly decreased natural Tregs but an increase in adaptive Tregs in their visceral adipose tissue as compared with lean control subjects. To further evaluate the pathogenic role of Tregs in insulin resistance, the db/db mouse model was used. Treg depletion using an anti-CD25 monoclonal antibody enhanced insulin resistance as shown by increased fasting blood glucose levels as well as an impaired insulin sensitivity. Moreover, Treg-depleted db/db mice developed increased signs of diabetic nephropathy, such as albuminuria and glomerular hyperfiltration. This was paralleled by a proinflammatory milieu in both murine visceral adipose tissue and the kidney. Conversely, adoptive transfer of CD4(+)FoxP3(+) Tregs significantly improved insulin sensitivity and diabetic nephropathy. Accordingly, there was increased mRNA expression of FoxP3 as well as less abundant proinflammatory CD8(+)CD69(+) T cells in visceral adipose tissue and kidneys of Treg-treated animals.

Conclusions: Data suggest a potential therapeutic value of Tregs to improve insulin resistance and end organ damage in type 2 diabetes by limiting the proinflammatory milieu.

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Treg depletion induces increased inflammation in visceral adipose tissue. Db/db mice were uninephrectomized at the age of 6 weeks and followed for 56 days. One group intraperitoneally received an anti-CD25 mAb the day of and 4 weeks after uninephrectomy (white bar, n = 8); the control group received an isotype control antibody (black bar, n = 8). The cytokine response in VAT (A) and SAT (B) was evaluated by real-time PCR. The fold increase to the mean expression of controls is provided. C: The percentage of CD4+CD69+ T cells was evaluated in VAT and SAT by flow cytometry. Pooled data of two independent experiments are shown. *P < 0.05. D: Representative dot plots from gated CD4+ T cells in VAT. FSC-H, forward scatter height.
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Figure 3: Treg depletion induces increased inflammation in visceral adipose tissue. Db/db mice were uninephrectomized at the age of 6 weeks and followed for 56 days. One group intraperitoneally received an anti-CD25 mAb the day of and 4 weeks after uninephrectomy (white bar, n = 8); the control group received an isotype control antibody (black bar, n = 8). The cytokine response in VAT (A) and SAT (B) was evaluated by real-time PCR. The fold increase to the mean expression of controls is provided. C: The percentage of CD4+CD69+ T cells was evaluated in VAT and SAT by flow cytometry. Pooled data of two independent experiments are shown. *P < 0.05. D: Representative dot plots from gated CD4+ T cells in VAT. FSC-H, forward scatter height.

Mentions: Since Treg lineage plasticity is influenced by insulin resistance, we next studied their pathogenic role in a murine model of type 2 diabetes. We therefore used a well-established model of murine type 2 diabetes (i.e., the leptin-deficient db/db mice). Tregs were eliminated in these mice using the Treg-depleting anti-CD25 antibody, which was injected intraperitoneally on days 1 and 28 after uninephrectomy. We chose this application schedule since we could not detect any CD4+CD25+ T cells in the inguinal lymph nodes 3 weeks after application of a single dose of the antibody (data not shown). Treg-depleted mice and the respective controls had a comparable body weight throughout the observation period of 56 days (Fig. 2A); however, fasting blood glucose levels were significantly increased as early as 21 days after uninephrectomy in Treg-depleted db/db mice when compared with vehicle-treated db/db mice (Fig. 2B). On day 56, insulin-sensitivity testing revealed that insulin lowered blood glucose levels more efficiently in vehicle-treated db/db mice compared with Treg-depleted db/db mice (Table 1). In addition, Treg-depleted db/db mice displayed a significantly increased HOMA-IR on day 56 as compared with control animals (Fig. 2C). To analyze whether these metabolic differences were also reflected by changes in the inflammatory profile within the mVAT and mSAT compartment, real-time PCR for mRNA expression of IFN-γ, IL-6, TNF-α, Gata-3, and IL-10 was performed. We could detect a prominent increase of the Th1 cytokines IFN-γ, IL-6, and TNF-α in mVAT of Treg-depleted db/db mice as compared with control animals (Fig. 3A). No difference in the mRNA expression of Gata-3 and IL-10 was detected in mVAT (Fig. 3A). Furthermore, we did not detect any difference in the expression of the respective transcripts in mSAT (Fig. 3B). In parallel, flow cytometry revealed increased numbers of activated CD4+CD69+ T cells in the mVAT of Treg-depleted mice (Fig. 3C and D), while no difference in the abundance of this cell population was found in mSAT (Fig. 3C). No difference in the percentage of CD8+ T cells and CD11c+ dendritic cells in mVAT was detected (data not shown).


Potential role of regulatory T cells in reversing obesity-linked insulin resistance and diabetic nephropathy.

Eller K, Kirsch A, Wolf AM, Sopper S, Tagwerker A, Stanzl U, Wolf D, Patsch W, Rosenkranz AR, Eller P - Diabetes (2011)

Treg depletion induces increased inflammation in visceral adipose tissue. Db/db mice were uninephrectomized at the age of 6 weeks and followed for 56 days. One group intraperitoneally received an anti-CD25 mAb the day of and 4 weeks after uninephrectomy (white bar, n = 8); the control group received an isotype control antibody (black bar, n = 8). The cytokine response in VAT (A) and SAT (B) was evaluated by real-time PCR. The fold increase to the mean expression of controls is provided. C: The percentage of CD4+CD69+ T cells was evaluated in VAT and SAT by flow cytometry. Pooled data of two independent experiments are shown. *P < 0.05. D: Representative dot plots from gated CD4+ T cells in VAT. FSC-H, forward scatter height.
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Figure 3: Treg depletion induces increased inflammation in visceral adipose tissue. Db/db mice were uninephrectomized at the age of 6 weeks and followed for 56 days. One group intraperitoneally received an anti-CD25 mAb the day of and 4 weeks after uninephrectomy (white bar, n = 8); the control group received an isotype control antibody (black bar, n = 8). The cytokine response in VAT (A) and SAT (B) was evaluated by real-time PCR. The fold increase to the mean expression of controls is provided. C: The percentage of CD4+CD69+ T cells was evaluated in VAT and SAT by flow cytometry. Pooled data of two independent experiments are shown. *P < 0.05. D: Representative dot plots from gated CD4+ T cells in VAT. FSC-H, forward scatter height.
Mentions: Since Treg lineage plasticity is influenced by insulin resistance, we next studied their pathogenic role in a murine model of type 2 diabetes. We therefore used a well-established model of murine type 2 diabetes (i.e., the leptin-deficient db/db mice). Tregs were eliminated in these mice using the Treg-depleting anti-CD25 antibody, which was injected intraperitoneally on days 1 and 28 after uninephrectomy. We chose this application schedule since we could not detect any CD4+CD25+ T cells in the inguinal lymph nodes 3 weeks after application of a single dose of the antibody (data not shown). Treg-depleted mice and the respective controls had a comparable body weight throughout the observation period of 56 days (Fig. 2A); however, fasting blood glucose levels were significantly increased as early as 21 days after uninephrectomy in Treg-depleted db/db mice when compared with vehicle-treated db/db mice (Fig. 2B). On day 56, insulin-sensitivity testing revealed that insulin lowered blood glucose levels more efficiently in vehicle-treated db/db mice compared with Treg-depleted db/db mice (Table 1). In addition, Treg-depleted db/db mice displayed a significantly increased HOMA-IR on day 56 as compared with control animals (Fig. 2C). To analyze whether these metabolic differences were also reflected by changes in the inflammatory profile within the mVAT and mSAT compartment, real-time PCR for mRNA expression of IFN-γ, IL-6, TNF-α, Gata-3, and IL-10 was performed. We could detect a prominent increase of the Th1 cytokines IFN-γ, IL-6, and TNF-α in mVAT of Treg-depleted db/db mice as compared with control animals (Fig. 3A). No difference in the mRNA expression of Gata-3 and IL-10 was detected in mVAT (Fig. 3A). Furthermore, we did not detect any difference in the expression of the respective transcripts in mSAT (Fig. 3B). In parallel, flow cytometry revealed increased numbers of activated CD4+CD69+ T cells in the mVAT of Treg-depleted mice (Fig. 3C and D), while no difference in the abundance of this cell population was found in mSAT (Fig. 3C). No difference in the percentage of CD8+ T cells and CD11c+ dendritic cells in mVAT was detected (data not shown).

Bottom Line: Obese patients with insulin resistance displayed significantly decreased natural Tregs but an increase in adaptive Tregs in their visceral adipose tissue as compared with lean control subjects.Conversely, adoptive transfer of CD4(+)FoxP3(+) Tregs significantly improved insulin sensitivity and diabetic nephropathy.Accordingly, there was increased mRNA expression of FoxP3 as well as less abundant proinflammatory CD8(+)CD69(+) T cells in visceral adipose tissue and kidneys of Treg-treated animals.

View Article: PubMed Central - PubMed

Affiliation: Clinical Division of Nephrology, Department of Internal Medicine, Medical University Graz, Graz, Austria. kathrin.eller@medunigraz.at

ABSTRACT

Objective: To assess the potential role of FoxP3-expressing regulatory T cells (Tregs) in reversing obesity-linked insulin resistance and diabetic nephropathy in rodent models and humans.

Research design and methods: To characterize the role of Tregs in insulin resistance, human visceral adipose tissue was first evaluated for Treg infiltration and second, the db/db mouse model was evaluated.

Results: Obese patients with insulin resistance displayed significantly decreased natural Tregs but an increase in adaptive Tregs in their visceral adipose tissue as compared with lean control subjects. To further evaluate the pathogenic role of Tregs in insulin resistance, the db/db mouse model was used. Treg depletion using an anti-CD25 monoclonal antibody enhanced insulin resistance as shown by increased fasting blood glucose levels as well as an impaired insulin sensitivity. Moreover, Treg-depleted db/db mice developed increased signs of diabetic nephropathy, such as albuminuria and glomerular hyperfiltration. This was paralleled by a proinflammatory milieu in both murine visceral adipose tissue and the kidney. Conversely, adoptive transfer of CD4(+)FoxP3(+) Tregs significantly improved insulin sensitivity and diabetic nephropathy. Accordingly, there was increased mRNA expression of FoxP3 as well as less abundant proinflammatory CD8(+)CD69(+) T cells in visceral adipose tissue and kidneys of Treg-treated animals.

Conclusions: Data suggest a potential therapeutic value of Tregs to improve insulin resistance and end organ damage in type 2 diabetes by limiting the proinflammatory milieu.

Show MeSH
Related in: MedlinePlus