Anti-PR3 immune responses induce segmental and necrotizing glomerulonephritis.

Area of Science:

• Immunology
• Pathology
• Autoimmunity

Background:

• Wegener's granulomatosis (WG) is a severe autoimmune vasculitis.
• Classic anti-neutrophil cytoplasmic antibodies (c-ANCA) against proteinase 3 (PR3) are a hallmark of WG.
• The precise role of PR3-specific immune responses in WG pathogenesis remains unclear.

Purpose of the Study:

• To investigate the pathogenic potential of PR3-specific autoimmune responses.
• To elucidate the role of the immune system's regulatory arm in WG development.
• To identify genetic factors influencing WG susceptibility.

Main Methods:

• Immunization of autoimmunity-prone non-obese diabetic (NOD) mice with recombinant mouse PR3 (rmPR3).
• Transfer of splenocytes from immunized mice into immunodeficient NOD-severe combined immunodeficiency (SCID) mice.
• Comparison of disease development in NOD-SCID mice receiving splenocytes from rmPR3-immunized donors versus control donors.
• Comparison of disease development in immunodeficient C57BL/6-RAG-1(-/-) mice.

Main Results:

• Immunization of NOD mice with rmPR3 induced high levels of c-ANCA but no disease.
• Transfer of splenocytes from rmPR3-immunized NOD mice into NOD-SCID recipients caused severe vasculitis and glomerulonephritis.
• No disease was observed in NOD-SCID mice receiving control splenocytes.
• Transfer of splenocytes from rmPR3-immunized C57BL/6 mice into C57BL/6-RAG-1(-/-) mice did not induce disease.

Conclusions:

• PR3-specific autoimmune responses are pathogenic and can induce WG-like disease in a susceptible host.
• Impaired immune regulation, as seen in NOD mice, is crucial for the development of PR3-induced autoimmunity.
• Complex, likely multi-genetic factors influence the regulation of WG development.