TNF and multiple sclerosis: As has been found from studies in experimental autoimmune encephalomyelitis (EAE) models resembling multiple sclerosis (MS), sildenafil can reduce disease-associated clinical symptoms in association with a decrease in the levels of inflammatory cytokines, such as IL-1β, TNFα, and IL-17, involved in neuroinflammation and disease pathogenesis, such as IL-1β, TNFα, and IL-17, likely through the direct targeting of nuclear factor kB (NFkB) [20].