TLR4 and infection: In contrast, the C3H‐HeJ strain is innate immune compromised due to spontaneous mutation in the tlr4 gene, and thus HeJ mice are unable to clear infections of the urinary tract with gram‐negative bacteria (Haraoka et al., 1999; Ragnarsdottir & Svanborg, 2012; Shahin, Engberg, Hagberg, & Svanborg, 1987).