Diet-induced Obesity Differentially Modulates Cardiac Inflammatory Status in the C57 and FVB Mouse Strains

Cardiovascular diseases correspond to the highest risk of sudden death worldwide, and obesity is largely related to be an increased risk factor. There is a higher prevalence of arterial hypertension in obese individuals, including the presence of cardiac hypertrophy. It is already known the role of toll-like receptors [TLR], mainly 2 and 4 in heart cells, as fundamental to the process of cardiac hypertrophy. Obesity has been studied as an activator of damage-associated molecular patterns [DAMPs], which use the TLR signaling pathway to increase the nuclear factor of inflammation, NF-kB, increasing cytokine expression in heart tissue. It's already known that FVB/N and C57BL/6 mouse strains have different behaviors in relation to metabolism, but the difference in cardiac tropism and innate immune system modulation are not clear.

The present study aimed to evaluate the contribution of innate immune factors to cardiac hypertrophy induced by an experimental model of obesity comparing two mouse strains: C57BL/6 and FVB/N. Both strains were submitted to a high-fat diet containing 23% protein, 35.5% carbohydrate, and 35.9% fat for 68 days. Hearts were collected, weighed, and submitted to RT-qPCR, and the serum was analyzed by Bioplex.

We observed an increase in heart mass after 68 days in both strains. This was followed by an increase of α-actin only in C57BL/6 while ANF was increased in FVB/N. Gene expression of innate immune components and inflammatory cytokines were only increased in C57BL/6, but not in FVB/N.

Based on the results obtained, we verified that C57BL/6 mice had a more robust action of innate immune system then FVB/N.