How to specifically target oncogenic KRAS-driven cancers while sparing normal tissues remains an unmet need in cancer therapy. In this issue of JEM, Jiang et al. (2022. J. Exp. Med.https://doi.org/10.1084/jem.20210739) leveraged KRAS-induced iron addiction in cancer cells to design a clever drug delivery approach to enable selective inhibition of KRAS signaling in mutant KRAS tumors but not in normal tissues, offering a new strategy for treating this largely incurable disease.
Many encapsulated bacteria use capsules to cause invasive diseases. However, it remains largely unknown how the capsules enhance bacterial virulence under in vivo infection conditions. Here we show that the capsules primarily target the liver to enhance bacterial survival at the onset of blood-borne infections. In a mouse sepsis model, the capsules enabled human pathogens Streptococcus pneumoniae and Escherichia coli to circumvent the recognition of liver-resident macrophage Kupffer cells (KCs) in a capsular serotype-dependent manner. In contrast to effective capture of acapsular bacteria by KCs, the encapsulated bacteria are partially (low-virulence types) or completely (high-virulence types) "untouchable" for KCs. We finally identified the asialoglycoprotein receptor (ASGR) as the first known capsule receptor on KCs to recognize the low-virulence serotype-7F and -14 pneumococcal capsules. Our data identify the molecular interplay between the capsules and KCs as a master controller of the fate and virulence of encapsulated bacteria, and suggest that the interplay is targetable for therapeutic control of septic infections.