The prebiotic fiber inulin ameliorates cardiac, adipose tissue, and hepatic pathology, but exacerbates hypertriglyceridemia in rats with metabolic syndrome

Prebiotics ameliorate dysbiosis and influence metabolism and the immune system, but their effects on cardiovascular complications in metabolic disorders remain largely unknown. We here investigated the effects of the soluble fiber inulin on cardiac, adipose tissue, and hepatic pathology as well as on metabolic disorders in DahlS.Z-Leprfa/Leprfa (DS/obese) rats, an animal model of metabolic syndrome (MetS). DS/obese rats and their homozygous lean (DahlS.Z-Lepr+/Lepr+, or DS/lean) littermate controls were fed a purified diet containing 5% or 20% inulin from 9 to 13 wk of age. The high-fiber diet ameliorated hypertension, left ventricular inflammation, fibrosis and diastolic dysfunction; attenuated adipose tissue inflammation and fibrosis; and alleviated the elevation of interleukin-6 levels, without affecting insulin resistance, in DS/obese rats. In addition, high fiber intake ameliorated lipid accumulation, inflammation, and fibrosis; attenuated the reduction in AMPK activity; upregulated sterol regulatory element-binding protein-1c gene expression; and increased the expression of microsomal triglyceride transfer protein gene in the liver of DS/obese rats. It also mitigated increases in total and non-high-density lipoprotein cholesterol levels but increased the triglyceride concentration in serum in these rats. None of these parameters were affected by high dietary fiber in DS/lean rats. The proportion of regulatory T cells in adipose tissue was influenced by dietary fiber but not by genotype. Our results indicate that inulin exacerbates hypertriglyceridemia but alleviates hypertension and cardiac injury as well as adipose tissue and hepatic pathology in MetS rats.NEW & NOTEWORTHY Prebiotics ameliorate dysbiosis and influence metabolism and the immune system, but their effects on cardiovascular complications in metabolic disorders remain largely unknown. Inulin ameliorated hypertension, cardiac injury, and diastolic dysfunction without affecting obesity or insulin resistance in a rat model of metabolic syndrome. The favorable cardiac effects of inulin may be related to inhibition of systemic inflammation associated with a reduction in circulating interleukin-6 levels. Additionally, inulin exacerbated hypertriglyceridemia but alleviates adipose tissue and hepatic pathology in these animals, as well as increased the number of regulatory T cells in adipose tissue.

Short chain fatty acids exchange: Is the cirrhotic, dysfunctional liver still able to clear them?

BACKGROUND & AIMS

Prebiotics are increasingly used to improve gut integrity. A presumed mechanism of their beneficial action is the synthesis of short chain fatty acids (SCFA: acetate, propionate and butyrate). High systemic concentrations of propionate and butyrate are toxic and can adversely affect the patient. In physiological situations the liver uses propionate and butyrate for energy metabolism. The aim of the present study was to investigate to which extent patients with liver cirrhosis are still able to metabolize portal derived SCFA in the liver.

METHODS

Twelve patients with liver cirrhosis and an intrahepatic portosystemic shunt (TIPSS) were studied. Blood was sampled from the femoral artery, portal and hepatic vein. Organ plasma flow was measured. Net release or uptake was calculated by multiplying the arteriovenous differences by plasma flow. SCFA plasma concentrations were measured using LC-MS.

RESULTS

Arterial concentrations were 124+/-12, 8+/-1 and 10+/-1micromol/l for acetate, propionate and butyrate, respectively. The gut produced 32.5+/-13.0, 4.8+/-1.3 and 6.2+/-2.1micromolkgbw(-1)h(-1) of acetate, propionate and butyrate, respectively. Assuming 70% portosystemic shunting, hepatic uptake of propionate and butyrate was 3.1+/-0.9 and 5.2+/-1.4micromolkgbw(-1)h(-1). Hepatic uptake of acetate was non significant (12.1+/-12.3micromolkgbw(-1)min(-1)). As a consequence of shunting, part of total acetate escaped from the splanchnic bed, which equalled 34.9+/-14.7micromolkgbw(-1)h(-1).

CONCLUSION

The liver of patients with stable cirrhosis is able to use butyrate and propionate, most likely preventing increased systemic concentrations. This suggests that prebiotics can be administered safely, but monitoring butyrate levels may be advisable in patients with diminished liver function.