IgG opsonized nuclear remnants from dead cells cause systemic inflammation in SLE

Area of Science:

• Immunology
• Cell Biology
• Autoimmune Diseases

Background:

• Patients with systemic lupus erythematosus (SLE) exhibit impaired recognition and clearance of apoptotic cells.
• Failure to clear dying cells results in secondary necrosis, releasing nuclear autoantigens that can trigger autoimmune responses.

Purpose of the Study:

• To investigate the role of secondarily necrotic cell-derived material (SNEC) in systemic inflammation in SLE.
• To determine the mechanisms by which SNEC interacts with phagocytes and autoantibodies (AAb) in SLE patients.

Main Methods:

• In vitro generation of SNEC using various methods.
• Analysis of SNEC characteristics, including DNA content and ligand binding.
• Assessment of AAb opsonization and phagocytosis of SNEC by blood-borne phagocytes.
• Measurement of inflammatory cytokine (IL-8, TNF-alpha) secretion following SNEC phagocytosis.
• Evaluation of the effect of DNase I treatment on SNEC uptake and cytokine production.

Main Results:

• SNEC is readily recognized and opsonized by AAb from SLE patients.
• Phagocytosis of opsonized SNEC by non-professional phagocytes leads to significant secretion of IL-8 and TNF-alpha.
• DNA within SNEC plays a crucial role, as DNase I treatment reduces both SNEC uptake and subsequent cytokine production.

Conclusions:

• Pro-inflammatory phagocytosis of IgG-opsonized cellular remnants by circulating phagocytes contributes to systemic inflammation in SLE.
• Targeting the interaction between SNEC, AAb, and phagocytes may offer therapeutic strategies for SLE.