Staphylococcus aureus activates the NLRP3 inflammasome in human and rat conjunctival goblet cells

PLoS One. 2013 Sep 10;8(9):e74010. doi: 10.1371/journal.pone.0074010. eCollection 2013.

Abstract

The conjunctiva is a moist mucosal membrane that is constantly exposed to an array of potential pathogens and triggers of inflammation. The NACHT, leucine rich repeat (LRR), and pyrin domain-containing protein 3 (NLRP3) is a Nod-like receptor that can sense pathogens or other triggers, and is highly expressed in wet mucosal membranes. NLRP3 is a member of the multi-protein complex termed the NLRP3 inflammasome that activates the caspase 1 pathway, inducing the secretion of biologically active IL-1β, a major initiator and promoter of inflammation. The purpose of this study was to: (1) determine whether NLRP3 is expressed in the conjunctiva and (2) determine whether goblet cells specifically contribute to innate mediated inflammation via secretion of IL-1β. We report that the receptors known to be involved in the priming and activation of the NLRP3 inflammasome, the purinergic receptors P2X4 and P2X7 and the bacterial Toll-like receptor 2 are present and functional in conjunctival goblet cells. Toxin-containing Staphylococcus aureus (S. aureus), which activates the NLRP3 inflammasome, increased the expression of the inflammasome proteins NLRP3, ASC and pro- and mature caspase 1 in conjunctival goblet cells. The biologically active form of IL-1β was detected in goblet cell culture supernatants in response to S. aureus, which was reduced when the cells were treated with the caspase 1 inhibitor Z-YVAD. We conclude that the NLRP3 inflammasome components are present in conjunctival goblet cells. The NRLP3 inflammasome appears to be activated in conjunctival goblet cells by toxin-containing S. aureus via the caspase 1 pathway to secrete mature IL1-β. Thus goblet cells contribute to the innate immune response in the conjunctiva by activation of the NLRP3 inflammasome.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Animals
  • Apoptosis
  • Carrier Proteins / metabolism*
  • Caspase 1 / metabolism
  • Conjunctiva / immunology
  • Conjunctiva / metabolism*
  • Conjunctiva / microbiology*
  • Cytoskeletal Proteins / metabolism
  • Enzyme Activation
  • Goblet Cells / metabolism
  • Humans
  • Inflammasomes*
  • Interleukin-1beta / metabolism
  • Male
  • NLR Family, Pyrin Domain-Containing 3 Protein
  • Rats
  • Receptors, Cytoplasmic and Nuclear / metabolism*
  • Receptors, Purinergic P2X4 / metabolism
  • Receptors, Purinergic P2X7 / metabolism
  • Staphylococcal Infections / immunology
  • Staphylococcal Infections / metabolism*
  • Staphylococcus aureus* / immunology
  • Toll-Like Receptor 2 / metabolism

Substances

  • Carrier Proteins
  • Cytoskeletal Proteins
  • Inflammasomes
  • Interleukin-1beta
  • NLR Family, Pyrin Domain-Containing 3 Protein
  • NLRP3 protein, human
  • Nlrp3 protein, rat
  • Receptors, Cytoplasmic and Nuclear
  • Receptors, Purinergic P2X4
  • Receptors, Purinergic P2X7
  • Toll-Like Receptor 2
  • Adenosine Triphosphate
  • Caspase 1