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Stearic acid induces proinflammatory cytokine production partly through activation of lactate-HIF1α pathway in chondrocytes.

Miao H, Chen L, Hao L, Zhang X, Chen Y, Ruan Z, Liang H - Sci Rep (2015)

Bottom Line: We found that stearic acid potentiated LDH-a-dependent production of lactate, which further stabilized HIF1α protein and increased VEGF and proinflammatory cytokine expression in primary mouse chondrocytes.Treatment with LDH-a and HIF1α inhibitors notably attenuated stearic acid-or high fat diet-stimulated proinflammatory cytokine production in vitro and in vivo.In conclusion, saturated free fatty acid induced proinflammatory cytokine production partly through activation of a novel lactate-HIF1α pathway in chondrocytes.

View Article: PubMed Central - PubMed

Affiliation: Department of Oncology, Southwest Hospital, Third Military Medical University, Chongqing 400038, China.

ABSTRACT
The biomechanics stress and chronic inflammation in obesity are causally linked to osteoarthritis. However, the metabolic factors mediating obesity-related osteoarthritis are still obscure. Here we scanned and identified at least two elevated metabolites (stearic acid and lactate) from the plasma of diet-induced obese mice. We found that stearic acid potentiated LDH-a-dependent production of lactate, which further stabilized HIF1α protein and increased VEGF and proinflammatory cytokine expression in primary mouse chondrocytes. Treatment with LDH-a and HIF1α inhibitors notably attenuated stearic acid-or high fat diet-stimulated proinflammatory cytokine production in vitro and in vivo. Furthermore, positive correlation of plasma lactate, cartilage HIF1α and cytokine levels with the body mass index was observed in subjects with osteoarthritis. In conclusion, saturated free fatty acid induced proinflammatory cytokine production partly through activation of a novel lactate-HIF1α pathway in chondrocytes. Our findings hold promise of developing novel clinical strategies for the management of obesity-related diseases such as osteoarthritis.

No MeSH data available.


Related in: MedlinePlus

FFA triggers production of proinflammatory cytokine and VEGF partly through LDH-a/HIF1-α pathway.(a~d) Primary mouse chondrocytes were transfected with siNC (20 nM), siLDH-a (20 nM) or Toll-like receptor 4 specific siRNA (siTLR4, 20 nM) for 12 h, treated with BSA (5%) or FFA (200 μM) for 24 h and then harvested for IL-6 (a), TNF-α (b), IL-1β (c), and VEGF (d) mRNA assay with Realtime PCR. (n = 4). (e~h) Male C57BL/6 mice were fed with a ND or HFD for 8 weeks and treated with LDH-a inhibitor (Oxamate, 500 mg/kg.d), HIF1α inhibitor (KG-548, 1 mg/kg.d), TLR4 inhibitor (TLR4-I, 1 mg/kg.d) or Oxamate (500 mg/kg.d) plus TLR4-I (1 mg/kg.d) for 2 weeks. Then, the cartilage of knee was isolated and subjected for IL-6 (e), TNF-α (f), IL-1β (g), and VEGF (h) mRNA assay with Realtime PCR. (n = 5). From (a) to (h), values not sharing a common superscript letter differ significantly (P < 0.05).
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f6: FFA triggers production of proinflammatory cytokine and VEGF partly through LDH-a/HIF1-α pathway.(a~d) Primary mouse chondrocytes were transfected with siNC (20 nM), siLDH-a (20 nM) or Toll-like receptor 4 specific siRNA (siTLR4, 20 nM) for 12 h, treated with BSA (5%) or FFA (200 μM) for 24 h and then harvested for IL-6 (a), TNF-α (b), IL-1β (c), and VEGF (d) mRNA assay with Realtime PCR. (n = 4). (e~h) Male C57BL/6 mice were fed with a ND or HFD for 8 weeks and treated with LDH-a inhibitor (Oxamate, 500 mg/kg.d), HIF1α inhibitor (KG-548, 1 mg/kg.d), TLR4 inhibitor (TLR4-I, 1 mg/kg.d) or Oxamate (500 mg/kg.d) plus TLR4-I (1 mg/kg.d) for 2 weeks. Then, the cartilage of knee was isolated and subjected for IL-6 (e), TNF-α (f), IL-1β (g), and VEGF (h) mRNA assay with Realtime PCR. (n = 5). From (a) to (h), values not sharing a common superscript letter differ significantly (P < 0.05).

Mentions: Saturated free fatty acid is the well-documented stimulator of TLR4, mediating inflammation response ubiquitously5721. To identify whether TLR4 is involved in LDH-a/lactate pathway-mediated cytokine production, stearic acid-induced inflammation response in primary chondrocytes with TLR4 or LDH-a silence was observed. Stearic acid-induced mRNA levels of IL-6 (Fig. 6a), TNF-α (Fig. 6b) and IL-1β (Fig. 6c) were largely decreased by a single silence of TLR4 (see Supplementary Fig. S3a) or LDH-a. Combined silence of TLR4 and LDH-a could fully prevent stearic acid-induced proinflammatory cytokine production (Fig. 6a~c). Thus we concluded that stearic acid/LDH-a/lactate pathway was TLR4-independent. Interestingly, stearic acid-stimulated VEGF expression was fully blocked by the silence of LDH-a, but not by TLR4 (Fig. 6d). To verify the aforementioned in vitro pathway (stearic acid/LDH-a/cytokines) in vivo, we treated the HFD-feeding mice with inhibitors of TLR4 (see Supplementary Fig. S3b), LDH-a or HIF1α (see Supplementary Fig. S3c) and observed cytokine production in mouse cartilage. The HFD-feeding stimulated mRNA expression of IL-6 (Fig. 6e), TNF-α (Fig. 6f) and IL-1β (Fig. 6g), and this effect was partly attenuated by a single treatment of TLR4, LDH-a or HIF1α inhibitors (Fig. 6e~g). Simultaneous administration with TLR4 and LDH-a inhibitors fully prevented HFD-feeding-induced proinflammatory cytokine production in mouse cartilage (Fig. 6e~g). It should be noted that the HFD-feeding-stimulated VEGF expression was prevented by LDH-a or HIF1α inhibitors, but not by TLR4 inhibitor (Fig. 6h). These results verified that stearic acid/LDH-a/HIF1α was a TLR4-independent novel pathway in chondrocytes.


Stearic acid induces proinflammatory cytokine production partly through activation of lactate-HIF1α pathway in chondrocytes.

Miao H, Chen L, Hao L, Zhang X, Chen Y, Ruan Z, Liang H - Sci Rep (2015)

FFA triggers production of proinflammatory cytokine and VEGF partly through LDH-a/HIF1-α pathway.(a~d) Primary mouse chondrocytes were transfected with siNC (20 nM), siLDH-a (20 nM) or Toll-like receptor 4 specific siRNA (siTLR4, 20 nM) for 12 h, treated with BSA (5%) or FFA (200 μM) for 24 h and then harvested for IL-6 (a), TNF-α (b), IL-1β (c), and VEGF (d) mRNA assay with Realtime PCR. (n = 4). (e~h) Male C57BL/6 mice were fed with a ND or HFD for 8 weeks and treated with LDH-a inhibitor (Oxamate, 500 mg/kg.d), HIF1α inhibitor (KG-548, 1 mg/kg.d), TLR4 inhibitor (TLR4-I, 1 mg/kg.d) or Oxamate (500 mg/kg.d) plus TLR4-I (1 mg/kg.d) for 2 weeks. Then, the cartilage of knee was isolated and subjected for IL-6 (e), TNF-α (f), IL-1β (g), and VEGF (h) mRNA assay with Realtime PCR. (n = 5). From (a) to (h), values not sharing a common superscript letter differ significantly (P < 0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

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f6: FFA triggers production of proinflammatory cytokine and VEGF partly through LDH-a/HIF1-α pathway.(a~d) Primary mouse chondrocytes were transfected with siNC (20 nM), siLDH-a (20 nM) or Toll-like receptor 4 specific siRNA (siTLR4, 20 nM) for 12 h, treated with BSA (5%) or FFA (200 μM) for 24 h and then harvested for IL-6 (a), TNF-α (b), IL-1β (c), and VEGF (d) mRNA assay with Realtime PCR. (n = 4). (e~h) Male C57BL/6 mice were fed with a ND or HFD for 8 weeks and treated with LDH-a inhibitor (Oxamate, 500 mg/kg.d), HIF1α inhibitor (KG-548, 1 mg/kg.d), TLR4 inhibitor (TLR4-I, 1 mg/kg.d) or Oxamate (500 mg/kg.d) plus TLR4-I (1 mg/kg.d) for 2 weeks. Then, the cartilage of knee was isolated and subjected for IL-6 (e), TNF-α (f), IL-1β (g), and VEGF (h) mRNA assay with Realtime PCR. (n = 5). From (a) to (h), values not sharing a common superscript letter differ significantly (P < 0.05).
Mentions: Saturated free fatty acid is the well-documented stimulator of TLR4, mediating inflammation response ubiquitously5721. To identify whether TLR4 is involved in LDH-a/lactate pathway-mediated cytokine production, stearic acid-induced inflammation response in primary chondrocytes with TLR4 or LDH-a silence was observed. Stearic acid-induced mRNA levels of IL-6 (Fig. 6a), TNF-α (Fig. 6b) and IL-1β (Fig. 6c) were largely decreased by a single silence of TLR4 (see Supplementary Fig. S3a) or LDH-a. Combined silence of TLR4 and LDH-a could fully prevent stearic acid-induced proinflammatory cytokine production (Fig. 6a~c). Thus we concluded that stearic acid/LDH-a/lactate pathway was TLR4-independent. Interestingly, stearic acid-stimulated VEGF expression was fully blocked by the silence of LDH-a, but not by TLR4 (Fig. 6d). To verify the aforementioned in vitro pathway (stearic acid/LDH-a/cytokines) in vivo, we treated the HFD-feeding mice with inhibitors of TLR4 (see Supplementary Fig. S3b), LDH-a or HIF1α (see Supplementary Fig. S3c) and observed cytokine production in mouse cartilage. The HFD-feeding stimulated mRNA expression of IL-6 (Fig. 6e), TNF-α (Fig. 6f) and IL-1β (Fig. 6g), and this effect was partly attenuated by a single treatment of TLR4, LDH-a or HIF1α inhibitors (Fig. 6e~g). Simultaneous administration with TLR4 and LDH-a inhibitors fully prevented HFD-feeding-induced proinflammatory cytokine production in mouse cartilage (Fig. 6e~g). It should be noted that the HFD-feeding-stimulated VEGF expression was prevented by LDH-a or HIF1α inhibitors, but not by TLR4 inhibitor (Fig. 6h). These results verified that stearic acid/LDH-a/HIF1α was a TLR4-independent novel pathway in chondrocytes.

Bottom Line: We found that stearic acid potentiated LDH-a-dependent production of lactate, which further stabilized HIF1α protein and increased VEGF and proinflammatory cytokine expression in primary mouse chondrocytes.Treatment with LDH-a and HIF1α inhibitors notably attenuated stearic acid-or high fat diet-stimulated proinflammatory cytokine production in vitro and in vivo.In conclusion, saturated free fatty acid induced proinflammatory cytokine production partly through activation of a novel lactate-HIF1α pathway in chondrocytes.

View Article: PubMed Central - PubMed

Affiliation: Department of Oncology, Southwest Hospital, Third Military Medical University, Chongqing 400038, China.

ABSTRACT
The biomechanics stress and chronic inflammation in obesity are causally linked to osteoarthritis. However, the metabolic factors mediating obesity-related osteoarthritis are still obscure. Here we scanned and identified at least two elevated metabolites (stearic acid and lactate) from the plasma of diet-induced obese mice. We found that stearic acid potentiated LDH-a-dependent production of lactate, which further stabilized HIF1α protein and increased VEGF and proinflammatory cytokine expression in primary mouse chondrocytes. Treatment with LDH-a and HIF1α inhibitors notably attenuated stearic acid-or high fat diet-stimulated proinflammatory cytokine production in vitro and in vivo. Furthermore, positive correlation of plasma lactate, cartilage HIF1α and cytokine levels with the body mass index was observed in subjects with osteoarthritis. In conclusion, saturated free fatty acid induced proinflammatory cytokine production partly through activation of a novel lactate-HIF1α pathway in chondrocytes. Our findings hold promise of developing novel clinical strategies for the management of obesity-related diseases such as osteoarthritis.

No MeSH data available.


Related in: MedlinePlus