Clinical and Morphological Presentation
The pathological process in this disease is progressive in nature. The core mechanism involves the interaction of autoantibodies produced by the organism with antigens of its own exocrine glands.
This interaction triggers a cascade of reactions leading to severe consequences:
- Glandular Tissue Destruction: Salivary and lacrimal glands are primarily affected. Their structure progressively deteriorates, leading to a sharp decrease in secretion production (hypofunction).
- Ocular Involvement: A deficiency in tear fluid precipitates keratoconjunctivitis sicca—a specific inflammation of the cornea and conjunctiva.
- Generalized Dryness: As the disease progresses, patients experience marked dryness across various mucous membranes. The mucosa of the nose, oral cavity, and genitalia become involved, significantly diminishing quality of life and creating favorable conditions for secondary complications.
Immunopathogenesis and Cytokine Cascade
The development of Sjögren syndrome is multifactorial. A chronic viral infection is considered one of the key triggers initiating the pathological process.
Tissue damage unfolds in a distinct sequence:
- Tissue Infiltration: Specific immune cells—CD4+ T lymphocytes—begin to dominate within the inflammatory foci of the exocrine glands.
- Mediator Release: These cells initiate a potent cytokine cascade. Active synthesis of pro-inflammatory molecules ensues: interleukin-1 (IL-1), interleukin-6 (IL-6), interferon-gamma (IFN-γ), and tumor necrosis factor-alpha (TNF-α).
- Epithelial Alteration: Exposed to high concentrations of these cytokines, glandular epithelial cells alter their properties—inducing expression of Class II HLA molecules on their surface.
- Vicious Cycle Closure: The appearance of Class II HLA molecules on cells atypical for such expression leads to hyperactivation of T and B lymphocytes. This, in turn, provokes a sharp amplification in antibody formation, including the massive production of autoantibodies that continue to destroy the gland.
Predisposing Factors and Diagnostics
Why do some patients develop this disease while others do not? Internal predisposing factors play a monumental role:
- Genetic Factors: A strong link between the disease and specific major histocompatibility complex antigens has been proven, notably carriage of HLA-DR3, -DQ1, and -DQ2 alleles.
- Hormonal Factors: Estrogens exert a significant influence on the development of the autoimmune process, which explains the gender distribution patterns of the pathology.
Clinical diagnosis relies on two primary pillars:
- Laboratory Criteria: Specific blood markers are routinely screened, including autoantibodies against nuclear antigens and rheumatoid factor.
- Histological Criteria: Microscopic examination of biopsied affected glandular tissue reveals characteristic foci of lymphoid infiltration, confirming the autoimmune nature of the inflammation.