iScience.  2022  May  20.  25(5): 104241
Josephine Brown, 
Georges Abboud, 
Longhuan Ma, 
Seung-Chul Choi, 
Nathalie Kanda, 
Leilani Zeumer-Spataro, 
Jean Lee, 
Weidan Peng, 
Joy Cagmat, 
Tamas Faludi, 
Mansour Mohamadzadeh, 
Timothy Garrett, 
Laura Mandik-Nayak, 
Alexander Chervonsky, 
Andras Perl, 
Laurence Morel.
 
  A skewed tryptophan metabolism has been reported in patients with lupus. Here, we investigated the mechanisms by which it occurs in lupus-susceptible mice, and how tryptophan metabolites exacerbate T cell activation. Metabolomic analyses demonstrated that tryptophan is differentially catabolized in lupus mice compared to controls and that the microbiota played a role in this skewing. There was no evidence for differential expression of tryptophan catabolic enzymes in lupus mice, further supporting a major contribution of the microbiota to skewing. However, isolated lupus T cells processed tryptophan differently, suggesting a contribution of T cell intrinsic factors. Functionally, tryptophan and its microbial product tryptamine increased T cell metabolism and mTOR activation, while kynurenine promoted interferon gamma production, all of which have been associated with lupus. These results showed that a combination of microbial and T cell intrinsic factors promotes the production of tryptophan metabolites that enhance inflammatory phenotypes in lupus T cells.
Keywords:  Biological sciences; Cell biology; Human metabolism; Immunology