Functional Toll-Like Receptor 9 Expression and CXCR3 Ligand Release in Pulmonary Sarcoidosis

Am J Respir Cell Mol Biol. 2016 Nov;55(5):749-757. doi: 10.1165/rcmb.2015-0278OC.


Sarcoidosis is a granulomatous disease characterized by a T-helper type 1 (Th1) cell-dominated alveolitis. As a role of bacteria in the pathogenesis of sarcoidosis has been discussed, Toll-like receptors (TLRs) may be involved in the initiation of a first immune reaction. We analyzed expression and functional relevance of several TLRs in bronchoalveolar lavage (BAL) cells from patients with pulmonary sarcoidosis. In parallel, we determined the release of C-X-C motif chemokine 9 (CXCL9), CXCL10, and CXCL11 by BAL cells from patients with pulmonary sarcoidosis. Nucleotide-binding oligomerization domain-containing protein (NOD) 1 and 2, TLR2, TLR6, and TLR9 expression by BAL cells was analyzed by real-time RT-PCR and cell surface expression by flow cytometry. Chemokine release was measured in BAL cell culture supernatants by ELISA. We found increased TLR9 mRNA expression in patients with sarcoidosis with chest X-ray type I and II and TLR9 protein expression in BAL cells from patients with chest X-ray type II and III. Stimulation with CpG nucleotides increased CXCL10 release by BAL cells from patients with sarcoidosis type II significantly compared with control subjects or other patients with sarcoidosis. In contrast, no increase in TNF, IL-12p40, or CXCL8 was detected. Spontaneous release of CXCL10, but not CXCL9 or CXCL11, by cultured BAL cells was also highest in cells from patients with chest X-ray type II. We found a significant association between TLR9 expression and CD4+ lymphocytes in BAL. Our data demonstrate that TLR9 ligands may contribute to the immunopathogenesis of sarcoidosis via induction of CXCL10 release in the alveolar macrophages.

Keywords: CXCR3 ligands; Toll-like receptors; alveolitis; bronchoalveolar lavage; sarcoidosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biopsy
  • Bronchi / pathology
  • Bronchoalveolar Lavage Fluid / cytology
  • Cells, Cultured
  • Chemokine CXCL10 / metabolism*
  • Flow Cytometry
  • Fluorescent Antibody Technique
  • Humans
  • Immunohistochemistry
  • Ligands
  • Nod1 Signaling Adaptor Protein / metabolism
  • Nod2 Signaling Adaptor Protein / metabolism
  • Oligodeoxyribonucleotides / pharmacology
  • Real-Time Polymerase Chain Reaction
  • Receptors, CXCR3 / metabolism*
  • Sarcoidosis, Pulmonary / metabolism*
  • Sarcoidosis, Pulmonary / pathology
  • Toll-Like Receptor 9 / metabolism*


  • CPG-oligonucleotide
  • CXCR3 protein, human
  • Chemokine CXCL10
  • Ligands
  • NOD1 protein, human
  • NOD2 protein, human
  • Nod1 Signaling Adaptor Protein
  • Nod2 Signaling Adaptor Protein
  • Oligodeoxyribonucleotides
  • Receptors, CXCR3
  • TLR9 protein, human
  • Toll-Like Receptor 9