The blood vessels of the brain and spinal cord form the blood-brain barrier to prevent the effects of bacteria and viruses. The blood-brain barrier does not allow immune cells as well as large proteins to pass through. However, bacteria and viruses can also infect the central nervous system, and intractable diseases caused by cancer and inflammation can develop. Against this background, the possibility that there is a gate through which pathogens and immune cells enter the central nervous system has been considered. However, the location of the gate and how it is formed have been unknown. This time, using an animal model of multiple sclerosis, we found that the blood vessel on the dorsal side of the fifth lumbar vertebra is the gate. We also found that the daily stimulation by gravity from the earth activates the nerves near the fifth lumbar vertebra, which in turn activates the "IL-6 amplifier," a mechanism that induces chronic inflammation, resulting in the formation of this gate.