The body’s immune reaction to increased levels of a toxic molecule, part of a bacterial species in the human gut, may reveal who is most at risk of developing lupus nephritis, according to a new study led by NYU Langone Health. In people with the disease, which often leads to long-term kidney damage, the body’s immune system attacks its own tissues. Bouts of lupus nephritis have been tied by past studies to upticks in growth of the bacterial species Ruminococcus gnavus. This triggers excess production of the key molecule, a lipoglycan, which is a key part of the bacterium’s outer wall.