Sjögren's syndrome: autoimmune epithelitis

Area of Science:

• Autoimmune diseases
• Immunology
• Pathophysiology

Background:

• Sjögren's syndrome (SS) is a chronic autoimmune disorder.
• Extraglandular manifestations commonly affect organs such as the kidneys, lungs, and liver.
• Previous research focused on lymphoid tissue involvement.

Purpose of the Study:

• To investigate the primary cellular targets in Sjögren's syndrome.
• To re-evaluate the pathophysiology of extraglandular manifestations in SS.
• To propose a new descriptive term for Sjögren's syndrome based on findings.

Main Methods:

• Clinical studies of kidney, lung, and liver involvement in SS patients.
• Radiologic (CT-scan) and histopathologic examination of pulmonary lesions.
• In situ hybridization to evaluate cytokine mRNA expression in minor salivary gland epithelial cells.
• Analysis of HLA class II molecule and c-myc protooncogene expression in epithelial cells.

Main Results:

• Kidney disease in SS predominantly involves interstitial nephritis with tubular dysfunction.
• Pulmonary lesions in SS initiate peribronchially, affecting one-fourth of patients.
• Liver involvement shows a pericholangeal round-cell infiltrate.
• Epithelial cells in SS inappropriately express HLA class II and c-myc, producing pro-inflammatory cytokines (IL-1, IL-6) and incorporating proviral DNA.

Conclusions:

• Epithelial cells are the primary affected cells in Sjögren's syndrome.
• Extraglandular manifestations are driven by lymphocyte attraction to epithelial tissues.
• The term "autoimmune epithelitis" is proposed to better describe the disease's pathology.