Reduced Fatty Acid Use from CD36 Deficiency Deteriorates Streptozotocin-Induced Diabetic Cardiomyopathy in Mice

Cardiac dysfunction is induced by multifactorial mechanisms in diabetes. Deranged fatty acid (FA) utilization, known as lipotoxicity, has long been postulated as one of the upstream events in the development of diabetic cardiomyopathy. CD36, a transmembrane glycoprotein, plays a major role in FA uptake in the heart. CD36 knockout (CD36KO) hearts exhibit reduced rates of FA transport with marked enhancement of glucose use. In this study, we explore whether reduced FA use by CD36 ablation suppresses the development of streptozotocin (STZ)-induced diabetic cardiomyopathy. We found that cardiac contractile dysfunction had deteriorated 16 weeks after STZ treatment in CD36KO mice. Although accelerated glucose uptake was not reduced in CD36KO-STZ hearts, the total energy supply, estimated by the pool size in the TCA cycle, was significantly reduced. The isotopomer analysis with 13C6-glucose revealed that accelerated glycolysis, estimated by enrichment of 13C2-citrate and 13C2-malate, was markedly suppressed in CD36KO-STZ hearts. Levels of ceramides, which are cardiotoxic lipids, were not elevated in CD36KO-STZ hearts compared to wild-type-STZ ones. Furthermore, increased energy demand by transverse aortic constriction resulted in synergistic exacerbation of contractile dysfunction in CD36KO-STZ mice. These findings suggest that CD36KO-STZ hearts are energetically compromised by reduced FA use and suppressed glycolysis; therefore, the limitation of FA utilization is detrimental to cardiac energetics in this model of diabetic cardiomyopathy.

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Abstract 13725: Limited Fatty Acid Use by CD36 Deficiency Accelerates the Development of Diabetic Cardiomyopathy

Circulation ◽

10.1161/circ.142.suppl_3.13725 ◽

2020 ◽

Vol 142 (Suppl_3) ◽

Author(s):

Ryo Kawakami ◽

Yogi Umbarawan ◽

Tatsuya Iso ◽

Norimichi Koitabashi ◽

Hiroaki Sunaga ◽

...

Keyword(s):

Fatty Acid ◽

Diabetic Cardiomyopathy ◽

Energy Demand ◽

Tca Cycle ◽

Contractile Dysfunction ◽

Transmembrane Glycoprotein ◽

Cardiac Contractile ◽

Cardiac Contractile Dysfunction ◽

Systolic And Diastolic Function

Diabetes is an independent risk factor for the development of heart failure. In diabetic hearts, it has been reported that increased fatty acid (FA) uptake and deranged FA use result in accumulation of cardiotoxic lipids and reduced cardiac efficiency that compromise systolic and diastolic function. To date, lipotoxicity hypothesis is prevailing as a key event driving diabetic cardiomyopathy and it is proposed that limited FA use is beneficial for diabetic hearts. However, it has not been fully studied whether limited FA use is actually beneficial in-vivo beating hearts in diabetes. CD36, a transmembrane glycoprotein, has a major role in FA uptake in the heart. CD36 knockout (CD36KO) hearts exhibit reduced rates of FA transport and oxidation with marked enhancement of glucose use. In this study, we explored whether reduced FA use by CD36 ablation suppresses the development of streptozotocin (STZ)-induced diabetic cardiomyopathy. Contrary to our expectations, we found that cardiac contractile dysfunction was deteriorated 16 weeks after STZ treatment in CD36KO mice. Although accelerated glucose uptake, estimated by 18 F-FDG uptake, was not reduced in CD36KO-STZ hearts, total energy supply, estimated by the pool size of the TCA cycle, was significantly reduced in CD36KO-STZ hearts. Isotopomer analysis with 13 C 6 -glucose revealed that accelerated glycolysis, estimated by enrichment of 13 C 3 -lactate, 13 C 2 -alanine, 13 C 2 -citrate and 13 C 2 -malate, in CD36KO hearts was markedly suppressed by STZ treatment. On the other hand, levels of ceramides, cardiotoxic lipids from excessive FA, were not elevated in CD36KO-STZ hearts compared to WT-STZ. Further, increased energy demand induced by transverse aortic constriction resulted in synergistic exacerbation of cardiac contractile dysfunction in CD36KO-STZ mice. These findings suggest that CD36KO-STZ hearts are energetically compromised by reduced FA use and suppressed glycolysis, leading to cardiac contractile dysfunction. Therefore, it is very likely that enhanced FA use in diabetic hearts occurs to compensate for reduced glucose use, and that limitation of FA utilization could be detrimental to the development of diabetic cardiomyopathy.

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Reduced fatty acid uptake aggravates cardiac contractile dysfunction in streptozotocin-induced diabetic cardiomyopathy

Scientific Reports ◽

10.1038/s41598-020-77895-1 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Yogi Umbarawan ◽

Ryo Kawakami ◽

Mas Rizky A. A. Syamsunarno ◽

Norimichi Koitabashi ◽

Hideru Obinata ◽

...

Keyword(s):

Fatty Acid ◽

Total Energy ◽

Diabetic Cardiomyopathy ◽

Energy Supply ◽

Contractile Dysfunction ◽

Acid Uptake ◽

Compensatory Response ◽

Fatty Acid Binding ◽

Cardiac Contractile ◽

Cardiac Contractile Dysfunction

AbstractDiabetes is an independent risk factor for the development of heart failure. Increased fatty acid (FA) uptake and deranged utilization leads to reduced cardiac efficiency and accumulation of cardiotoxic lipids, which is suggested to facilitate diabetic cardiomyopathy. We studied whether reduced FA uptake in the heart is protective against streptozotocin (STZ)-induced diabetic cardiomyopathy by using mice doubly deficient in fatty acid binding protein 4 (FABP4) and FABP5 (DKO mice). Cardiac contractile dysfunction was aggravated 8 weeks after STZ treatment in DKO mice. Although compensatory glucose uptake was not reduced in DKO-STZ hearts, total energy supply, estimated by the pool size in the TCA cycle, was significantly reduced. Tracer analysis with 13C6-glucose revealed that accelerated glycolysis in DKO hearts was strongly suppressed by STZ treatment. Levels of ceramides, cardiotoxic lipids, were similarly elevated by STZ treatment. These findings suggest that a reduction in total energy supply by reduced FA uptake and suppressed glycolysis could account for exacerbated contractile dysfunction in DKO-STZ hearts. Thus, enhanced FA uptake in diabetic hearts seems to be a compensatory response to reduced energy supply from glucose, and therefore, limited FA use could be detrimental to cardiac contractile dysfunction due to energy insufficiency.

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Western diet, but not high fat diet, causes derangements of fatty acid metabolism and contractile dysfunction in the heart of Wistar rats

Biochemical Journal ◽

10.1042/bj20070392 ◽

2007 ◽

Vol 406 (3) ◽

pp. 457-467 ◽

Cited By ~ 102

Author(s):

Christopher R. Wilson ◽

Mai K. Tran ◽

Katrina L. Salazar ◽

Martin E. Young ◽

Heinrich Taegtmeyer

Keyword(s):

Fatty Acid ◽

Fatty Acid Oxidation ◽

High Fat Diet ◽

Ex Vivo ◽

Western Diet ◽

Acid Oxidation ◽

Contractile Dysfunction ◽

High Fat ◽

Cardiac Contractile ◽

Cardiac Contractile Dysfunction

Obesity and diabetes are associated with increased fatty acid availability in excess of muscle fatty acid oxidation capacity. This mismatch is implicated in the pathogenesis of cardiac contractile dysfunction and also in the development of skeletal-muscle insulin resistance. We tested the hypothesis that ‘Western’ and high fat diets differentially cause maladaptation of cardiac- and skeletal-muscle fatty acid oxidation, resulting in cardiac contractile dysfunction. Wistar rats were fed on low fat, ‘Western’ or high fat (10, 45 or 60% calories from fat respectively) diet for acute (1 day to 1 week), short (4–8 weeks), intermediate (16–24 weeks) or long (32–48 weeks) term. Oleate oxidation in heart muscle ex vivo increased with high fat diet at all time points investigated. In contrast, cardiac oleate oxidation increased with Western diet in the acute, short and intermediate term, but not in the long term. Consistent with fatty acid oxidation maladaptation, cardiac power decreased with long-term Western diet only. In contrast, soleus muscle oleate oxidation (ex vivo) increased only in the acute and short term with either Western or high fat feeding. Fatty acid-responsive genes, including PDHK4 (pyruvate dehydrogenase kinase 4) and CTE1 (cytosolic thioesterase 1), increased in heart and soleus muscle to a greater extent with feeding a high fat diet compared with a Western diet. In conclusion, we implicate inadequate induction of a cassette of fatty acid-responsive genes, and impaired activation of fatty acid oxidation, in the development of cardiac dysfunction with Western diet.

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