Is there any relationship between atherosclerosis and multiple sclerosis?

Yes, unrelated: Atherosclerosis is a progressive disease also known as hardening of the arteries - fat, cholesterol and other substances build up in the arteries forming plaque and reducing the area in which blood can flow. Multiple sclerosis is an autoimmune disease that affects the brain/central nervous system and impedes function in attacks that tend to increase in severity and duration.

No relationship: Atherosclerosis is due to aging, hypertension, high blood lipids, diabetes, hyperhomocysteinemia, etc., and involves progressive arterial narrowing. Ms occurs in younger folks, and is an autoimmune process. Of interest, the historical low fat swank diet seemed helpful in many, and this is a good diet for heart disease prevention. In short, no pathogenic association with vascular disease.