Toll-like receptor family (TLR) has a fundamental role in pathogen recognition and activation of innate immunity. TLRs are highly conserved from Drosophila to humans and share structural and functional similarities. TLRs recognize pathogen-associated molecular patterns (PAMP) that are expressed on infectious agents, and mediate the production of cytokines necessary for the development of effective immunity. Toll-like receptor 4 (TLR4) cooperates with LY96 and CD14 to mediate the innate immune response to bacterial lipopolysaccharide (LPS). TLR4 acts via MYD88, TIRAP and TRAF6 to lead to NFkB activation, cytokine secretion and inflammatory response. TLR4 is highly expressed in placenta, spleen and peripheral blood leukocytes. Genetic variation in TLR4 is associated with age-related macular degeneration 10 (ARMD10), an irreversible vision loss.