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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 potentiates lactate production via activating LDH-a expression.(a) Relative FFA levels in the supernatant of cultured mouse primary chondrocytes treated with lactate (25 mM) or vehicle control. (b) Relative lactate levels in the supernatant of cultured mouse primary chondrocytes treated with FFA (200 μM) or 5% BSA. (n = 3, *P < 0.05). (c) Immunoblotting assay of LDH-a in mouse primary chondrocytes transfected with siNC (20 nM) or LDH-a specific siRNA (siLDH-a, 20 nM) for 12 h plus additional treatment with BSA (5%) or FFA (200 μM) for 24 h. (d) Relative lactate level in the supernatant of cultured mouse primary chondrocytes treated as described in (c). (n = 3). (e) Relative lactate level in the supernatant of cultured mouse primary chondrocytes treated with BSA (5%) or FFA (200 μM) puls Oxamate (100 nM) or vehicle control for 24 h. Values not sharing a common superscript letter differ significantly. (n = 3). (f) Relative plasma FFA levels in the mice with HFD for 0, 1, 7, 14, 28 or 56 days. (n = 5). (g) Relative plasma lactate levels in the mice with HFD for 0, 1, 7, 14, 28 or 56 days. (n = 5). (h) Relative plasma VEGF level in the mice with HFD for 0, 1, 7, 14, 28 or 56 days. (n = 5). (i) Relative plasma lactate levels in the mice fed with HFD for 28 days plus Oxamate (500 mg/kg.d) for one week. (n = 5). From (d) to (i), values not sharing a common superscript letter differ significantly (P < 0.05).
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f5: FFA potentiates lactate production via activating LDH-a expression.(a) Relative FFA levels in the supernatant of cultured mouse primary chondrocytes treated with lactate (25 mM) or vehicle control. (b) Relative lactate levels in the supernatant of cultured mouse primary chondrocytes treated with FFA (200 μM) or 5% BSA. (n = 3, *P < 0.05). (c) Immunoblotting assay of LDH-a in mouse primary chondrocytes transfected with siNC (20 nM) or LDH-a specific siRNA (siLDH-a, 20 nM) for 12 h plus additional treatment with BSA (5%) or FFA (200 μM) for 24 h. (d) Relative lactate level in the supernatant of cultured mouse primary chondrocytes treated as described in (c). (n = 3). (e) Relative lactate level in the supernatant of cultured mouse primary chondrocytes treated with BSA (5%) or FFA (200 μM) puls Oxamate (100 nM) or vehicle control for 24 h. Values not sharing a common superscript letter differ significantly. (n = 3). (f) Relative plasma FFA levels in the mice with HFD for 0, 1, 7, 14, 28 or 56 days. (n = 5). (g) Relative plasma lactate levels in the mice with HFD for 0, 1, 7, 14, 28 or 56 days. (n = 5). (h) Relative plasma VEGF level in the mice with HFD for 0, 1, 7, 14, 28 or 56 days. (n = 5). (i) Relative plasma lactate levels in the mice fed with HFD for 28 days plus Oxamate (500 mg/kg.d) for one week. (n = 5). From (d) to (i), values not sharing a common superscript letter differ significantly (P < 0.05).

Mentions: Given that both stearic acid and lactate could mimic the hypoxia state and regulate HIF1α activity, we presumed that there might be a reciprocal regulatory role between stearic acid and lactate. In primary mouse chondrocytes, lactate treatment exerted no effects on the production of free fatty acids (Fig. 5a), while the treatment with stearic acid notably induced lactate production (Fig. 5b). Further, we demonstrated that stearic acid could induce the expression of LDH-a, a key enzyme for lactate production (Fig. 5c). siRNA-mediated LDH-a silence abolished stearic acid-stimulated lactate production in primary mouse chondrocytes (Fig. 5c~d). To confirm the stimulatory role of stearic acid on lactate production via LDH-a, an inhibitor (Oxamate) of LDH-a activity was employed and identical results were obtained (Fig. 5e and Supplementary Fig. 2). Furthermore, in vivo studies were performed to verify the aforementioned findings in vitro. The HFD treatment stimulated the levels of free fatty acids (Fig. 5f) and lactate (Fig. 5g) in mouse plasma in a time-dependent manner. Likewise, the plasma VEGF exerted a similar altering pattern as free fatty acids and lactate (Fig. 5h). Interestingly, the HFD-induced lactate production was abolished by additional treatment with the LDH-a inhibitor Oxamate (Fig. 5i).


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 potentiates lactate production via activating LDH-a expression.(a) Relative FFA levels in the supernatant of cultured mouse primary chondrocytes treated with lactate (25 mM) or vehicle control. (b) Relative lactate levels in the supernatant of cultured mouse primary chondrocytes treated with FFA (200 μM) or 5% BSA. (n = 3, *P < 0.05). (c) Immunoblotting assay of LDH-a in mouse primary chondrocytes transfected with siNC (20 nM) or LDH-a specific siRNA (siLDH-a, 20 nM) for 12 h plus additional treatment with BSA (5%) or FFA (200 μM) for 24 h. (d) Relative lactate level in the supernatant of cultured mouse primary chondrocytes treated as described in (c). (n = 3). (e) Relative lactate level in the supernatant of cultured mouse primary chondrocytes treated with BSA (5%) or FFA (200 μM) puls Oxamate (100 nM) or vehicle control for 24 h. Values not sharing a common superscript letter differ significantly. (n = 3). (f) Relative plasma FFA levels in the mice with HFD for 0, 1, 7, 14, 28 or 56 days. (n = 5). (g) Relative plasma lactate levels in the mice with HFD for 0, 1, 7, 14, 28 or 56 days. (n = 5). (h) Relative plasma VEGF level in the mice with HFD for 0, 1, 7, 14, 28 or 56 days. (n = 5). (i) Relative plasma lactate levels in the mice fed with HFD for 28 days plus Oxamate (500 mg/kg.d) for one week. (n = 5). From (d) to (i), values not sharing a common superscript letter differ significantly (P < 0.05).
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f5: FFA potentiates lactate production via activating LDH-a expression.(a) Relative FFA levels in the supernatant of cultured mouse primary chondrocytes treated with lactate (25 mM) or vehicle control. (b) Relative lactate levels in the supernatant of cultured mouse primary chondrocytes treated with FFA (200 μM) or 5% BSA. (n = 3, *P < 0.05). (c) Immunoblotting assay of LDH-a in mouse primary chondrocytes transfected with siNC (20 nM) or LDH-a specific siRNA (siLDH-a, 20 nM) for 12 h plus additional treatment with BSA (5%) or FFA (200 μM) for 24 h. (d) Relative lactate level in the supernatant of cultured mouse primary chondrocytes treated as described in (c). (n = 3). (e) Relative lactate level in the supernatant of cultured mouse primary chondrocytes treated with BSA (5%) or FFA (200 μM) puls Oxamate (100 nM) or vehicle control for 24 h. Values not sharing a common superscript letter differ significantly. (n = 3). (f) Relative plasma FFA levels in the mice with HFD for 0, 1, 7, 14, 28 or 56 days. (n = 5). (g) Relative plasma lactate levels in the mice with HFD for 0, 1, 7, 14, 28 or 56 days. (n = 5). (h) Relative plasma VEGF level in the mice with HFD for 0, 1, 7, 14, 28 or 56 days. (n = 5). (i) Relative plasma lactate levels in the mice fed with HFD for 28 days plus Oxamate (500 mg/kg.d) for one week. (n = 5). From (d) to (i), values not sharing a common superscript letter differ significantly (P < 0.05).
Mentions: Given that both stearic acid and lactate could mimic the hypoxia state and regulate HIF1α activity, we presumed that there might be a reciprocal regulatory role between stearic acid and lactate. In primary mouse chondrocytes, lactate treatment exerted no effects on the production of free fatty acids (Fig. 5a), while the treatment with stearic acid notably induced lactate production (Fig. 5b). Further, we demonstrated that stearic acid could induce the expression of LDH-a, a key enzyme for lactate production (Fig. 5c). siRNA-mediated LDH-a silence abolished stearic acid-stimulated lactate production in primary mouse chondrocytes (Fig. 5c~d). To confirm the stimulatory role of stearic acid on lactate production via LDH-a, an inhibitor (Oxamate) of LDH-a activity was employed and identical results were obtained (Fig. 5e and Supplementary Fig. 2). Furthermore, in vivo studies were performed to verify the aforementioned findings in vitro. The HFD treatment stimulated the levels of free fatty acids (Fig. 5f) and lactate (Fig. 5g) in mouse plasma in a time-dependent manner. Likewise, the plasma VEGF exerted a similar altering pattern as free fatty acids and lactate (Fig. 5h). Interestingly, the HFD-induced lactate production was abolished by additional treatment with the LDH-a inhibitor Oxamate (Fig. 5i).

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