The effect of NLRP3 deficiency on immune response and gene regulation
The NLRP1 and NLRP3 inflammasomes are critical immune signaling hubs that drive cytokine release and inflammatory cell death, and have been implicated in the pathogenesis of diverse diseases. Much of our understanding of inflammasome biology stems from experiments performed in transgenic mouse lines. However, the unavoidable retention of highly polymorphic genomic regions in transgenic mice can confound results, leading to false conclusions, and delaying scientific progress and clinical development. Here, we found that the most commonly used NLRP3 deficient mouse strain, unknowingly contains a substantial region of 129 genome proximal to Nlrp3, causing a hypersensitive response to NLRP1 stimulation, altered gene regulation across multiple cell-types, and the misexpression of the key macrophage cell surface marker TIM4, independently of NLRP3 deficiency. Our results demonstrate that phenotypes previously attributed to the loss of NLRP3 expression may in fact be a byproduct of passenger mutations, and that conventional macrophage identification is obsolete. These data, and our validation of a previously unreported conditional Nlrp3 allele, are critical for the immunology community in ensuring correct data interpretation and improving experimental design. Furthermore, they open new questions in how genetically distinct mouse strains regulate inflammasome protein stability and expression to restrict excessive inflammation.