Answer
Shizuo Akira primarily expanded on Bruce Beutler's initial research on TLRs. Akira was a Japanese immunologist who studied the role of Toll-like receptors (TLRs) in the immune system. He discovered that TLRs are receptors that recognize and respond to pathogen-associated molecular patterns (PAMPs), which are molecules found on the surface of bacteria, viruses, and other pathogens. Akira's work helped to explain how the immune system recognizes and fights off infection.