The core alarm system of the human immune system is exclusive to placental mammals and is completely missing in birds, reptiles, and even egg-laying mammals.
April 29, 2026
Original Paper
Eutherian NLRP3 is distinguished by conserved regulatory features absent in non-eutherian NLRP3-like proteins
bioRxiv · 10.64898/2026.04.26.720791
The Takeaway
The NLRP3 inflammasome was long believed to be a universal defense mechanism shared by all animals with a backbone. Recent genetic analysis shows that this specific immune sensor only evolved about 160 million years ago in the ancestors of humans, dogs, and whales. Other vertebrates use different, less specialized versions of these proteins to detect infections and damage. This means the way our bodies fight inflammation is a relatively new evolutionary experiment rather than an ancient biological rule. Understanding these mammal specific features helps explain why humans are uniquely susceptible to certain inflammatory diseases that other animals never experience. It changes our basic map of how immunity has evolved across the tree of life.
From the abstract
NLRP3 is a cytosolic pattern recognition receptor that controls the formation of an inflammasome, a multimolecular complex that cleaves the pro-inflammatory cytokines interleukin-1{beta} and interleukin-18 into their bioactive forms. NLRP3 has been widely assumed to be conserved across vertebrates, suggesting it plays an indispensable role within the vertebrate innate immune system. Here, we used gene synteny, phylogeny, and structural analysis to examine the evolutionary origins of NLRP3 in gre