Inflammatory caspases are critical for enhanced cell death in the target tissue of Sjögren's syndrome before disease onset

Immunol Cell Biol. 2009 Jan;87(1):81-90. doi: 10.1038/icb.2008.70. Epub 2008 Oct 21.

Abstract

To date, little is known about why exocrine glands are subject to immune cell infiltrations in Sjögren's syndrome (SjS). Studies with SjS-prone C57BL/6.NOD-Aec1Aec2 mice showed altered glandular homeostasis in the submandibular glands (SMX) at 8 weeks before disease onset and suggested the potential involvement of inflammatory caspases (caspase-11 and -1). To determine whether inflammatory caspases are critical for the increased epithelial cell death before SjS-like disease, we investigated molecular events involving caspase-11/caspase-1 axis. Our results revealed concurrent upregulation of caspase-11 in macrophages, STAT-1 activity, caspase-1 activity and apoptotic epithelial cells in the SMX of C57BL/6.NOD-Aec1Aec2 at 8 weeks. Caspase-1, a critical factor for interleukin (IL)-1beta and IL-18 secretion, resulted in an elevated level of IL-18 in saliva. Interestingly, TUNEL-positive cells in the SMX of C57BL/6.NOD-Aec1Aec2 were not colocalized with caspase-11, indicating that caspase-11 functions in a noncell autonomous manner. Increased apoptosis of a human salivary gland (HSG) cell line occurred only in the presence of lipopolysaccharide (LPS-) and interferon (IFN)-gamma-stimulated human monocytic THP-1 cells, which was reversed when caspase-1 in THP-1 cells was targeted by siRNA. Taken together, our study discovered that inflammatory caspases are essential in promoting a pro-inflammatory microenvironment and influencing increased epithelial cell death in the target tissues of SjS before disease onset.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Apoptosis / immunology*
  • Caspase 1 / genetics
  • Caspase 1 / metabolism*
  • Caspase 3 / genetics
  • Caspase 3 / metabolism
  • Caspases / genetics
  • Caspases / metabolism*
  • Caspases, Initiator
  • Cell Line
  • Cells, Cultured
  • Dendritic Cells / enzymology
  • Dendritic Cells / immunology
  • Epithelial Cells / enzymology
  • Epithelial Cells / immunology
  • Epithelial Cells / pathology
  • Female
  • Humans
  • Interferon-gamma / immunology
  • Interferon-gamma / metabolism
  • Interleukin-18 / immunology
  • Interleukin-18 / metabolism
  • Interleukin-1beta / immunology
  • Interleukin-1beta / metabolism
  • Macrophages / enzymology
  • Macrophages / immunology
  • Mice
  • Mice, Inbred C57BL
  • NF-kappa B / immunology
  • NF-kappa B / metabolism
  • STAT1 Transcription Factor / immunology
  • STAT1 Transcription Factor / metabolism
  • Saliva / immunology
  • Saliva / metabolism
  • Salivary Glands / enzymology
  • Salivary Glands / immunology*
  • Salivary Glands / pathology
  • Sjogren's Syndrome / enzymology
  • Sjogren's Syndrome / immunology*
  • Sjogren's Syndrome / pathology
  • Up-Regulation

Substances

  • Interleukin-18
  • Interleukin-1beta
  • NF-kappa B
  • STAT1 Transcription Factor
  • Interferon-gamma
  • Casp4 protein, mouse
  • Caspase 3
  • Caspases
  • Caspases, Initiator
  • Caspase 1