Interleukin-1 receptor 8 (IL-1R8) is a member of the IL-1Rs family act as a negative regulator of Toll-Like Receptor 4 (TLR4) signaling. The current data suggest only the Toll/IL-1R (TIR) domain in IL-1R8 is required to inhibit the signalling; however, we lack knowledge of the mechanism interfacing between TLR4 TIR and IL-1R8 TIR, leading to TLR4 inhibition. Therefore, to fully elucidate the precise interface between the TIR domains, knowledge of the structure of this assembly is required. Thus, we successfully purified the TIR domain and TIR domain associated with a flexible loop known as a tail of mouse IL-1R8. To solve the structure using X-ray crystallography, we searched for conditions that yield crystal. However, no crystal growth was detected in the conditions we tested. We found out using negative stain electron microscopy, that mIL-1R8 TIR domain and MyD88- adaptor-like (MAL) TIR domain form a co-filament. which we are trying to solve the structure of the filament using cryo-EM.