Circulating Metabolomic Signature in Generalized Pustular Psoriasis Blunts Monocyte Hyperinflammation by Triggering Amino Acid Response

Front Immunol. 2021 Sep 8;12:739514. doi: 10.3389/fimmu.2021.739514. eCollection 2021.

Abstract

Generalized pustular psoriasis (GPP), the most grievous variant of psoriasis, is featured by dysregulated systemic inflammatory response. The cellular and molecular basis of GPP is poorly understood. Blood monocytes are key players of host defense and producers of inflammatory cytokines including IL-1β. How the immune response of monocytes is affected by metabolic internal environment in GPP remains unclear. Here, we performed a metabolomic and functional investigation of GPP serum and monocytes. We demonstrated a significant increase in IL-1β production from GPP monocytes. In GPP circulation, serum amyloid A (SAA), an acute-phase reactant, was dramatically increased, which induced the release of IL-1β from monocytes in a NLRP3-dependent manner. Using metabolomic analysis, we showed that GPP serum exhibited an amino acid starvation signature, with glycine, histidine, asparagine, methionine, threonine, lysine, valine, isoleucine, tryptophan, tyrosine, alanine, proline, taurine and cystathionine being markedly downregulated. In functional assay, under amino acid starvation condition, SAA-stimulated mature IL-1β secretion was suppressed. Mechanistically, at post-transcriptional level, amino acid starvation inhibited the SAA-mediated reactive oxygen species (ROS) formation and NLRP3 inflammasome activation. Moreover, the immune-modulatory effect of amino acid starvation was blocked by silencing general control nonderepressible 2 kinase (GCN2), suggesting the involvement of amino acid response (AAR) pathway. Collectively, our results suggested that decreased serum amino acids in GPP blunted the innate immune response in blood monocytes through AAR pathway, serving as a feedback mechanism preventing excessive inflammation in GPP.

Keywords: GCN2 2; IL-1β; amino acid; generalized pustular psoriasis; metabolomics; monocyte.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Amino Acids / metabolism*
  • Biomarkers / blood
  • Case-Control Studies
  • Cells, Cultured
  • Female
  • Humans
  • Inflammasomes / metabolism
  • Inflammation Mediators / metabolism*
  • Interleukin-1beta / metabolism
  • Male
  • Metabolome*
  • Metabolomics
  • Middle Aged
  • Monocytes / immunology
  • Monocytes / metabolism*
  • NLR Family, Pyrin Domain-Containing 3 Protein / metabolism
  • Protein Serine-Threonine Kinases / metabolism
  • Psoriasis / blood*
  • Psoriasis / diagnosis
  • Psoriasis / immunology
  • Skin Diseases, Vesiculobullous / blood*
  • Skin Diseases, Vesiculobullous / diagnosis
  • Skin Diseases, Vesiculobullous / immunology

Substances

  • Amino Acids
  • Biomarkers
  • IL1B protein, human
  • Inflammasomes
  • Inflammation Mediators
  • Interleukin-1beta
  • NLR Family, Pyrin Domain-Containing 3 Protein
  • NLRP3 protein, human
  • EIF2AK4 protein, human
  • Protein Serine-Threonine Kinases