(243) Immune-Related Effects of the Standard American Diet in Rodents

Obesity is a pro-inflammatory state that can contribute to chronic pain. Additionally, a poor-quality diet, high in carbohydrates can activate the immune system, further leading to inflammation. We have shown that our Standard American Diet (SAD) can increase peripheral markers of inflammation and prolong recovery from injury presumably through increased activation of immune cells in the spinal cord. Here, we demonstrate that long-term consumption of the SAD can enhance immune cell activation in the spinal cord, increase immune cell infiltration into the cord and that immune cells are required for enhanced SAD-related negative effects on recovery. First, spinal cords were imaged for Iba1, a marker of microglia/macrophage activation after chronic consumption of the SAD before and following inflammatory injury. As expected, SAD consumption increased activation at all time points (except for day 1 post-injury), perhaps explaining the protracted recovery observed. Second, long-term consumption of the SAD increased T cell infiltration into the spinal cord before and following injury and this effect was prevented by dietary intervention with our Anti-Inflammatory Diet. Similar findings were observed in the brains. Finally, genetically-modified mice lacking the ability to activate microglia to the M1 phenotype showed no protracted recovery from inflammatory injury following long-term consumption of the SAD. Together, these data support the notion that poor-quality diet activates both the innate and adaptive immune systems and that this activation is required for the diet-induced negative behavioral effects following injury. Future studies will examine the impact of the SAD on markers of oxidative stress as a potential mechanism underlying the development of insulin sensitivity and diabetes mellitus.