Pregnancy, chimerism and lupus nephritis: a multi-centre study.

Area of Science:

• Nephrology
• Immunology
• Genetics

Background:

• Chimerism, the presence of genetically distinct cell populations within an individual, is observed more frequently in the kidneys of women with lupus nephritis compared to healthy individuals.
• Pregnancy is a significant source of chimerism, yet its precise role in the development and persistence of chimerism in systemic lupus erythematosus (SLE) remains unclear.

Purpose of the Study:

• To investigate the relationship between pregnancy history and the presence of chimerism in the kidneys of women diagnosed with lupus nephritis.
• To explore potential alternative sources of chimerism in SLE patients who do not report a history of pregnancy.

Main Methods:

• Analysis of renal biopsies from patients in the First Dutch Lupus Nephritis Study to identify Y-chromosome-positive cells using in-situ hybridization.
• Collection of detailed reproductive histories, including pregnancies and miscarriages, through a standardized questionnaire.

Main Results:

• Chimerism was detected in 46% of renal biopsies from women with lupus nephritis.
• Women with lupus nephritis and chimerism reported a significantly higher number of pregnancies compared to non-chimeric women with lupus nephritis (P=0.04).
• A notable proportion of chimeric women did not report any pregnancies, suggesting other origins for chimerism.

Conclusions:

• The study found no definitive association between pregnancy history and chimerism in lupus nephritis patients.
• The presence of chimerism in women without a reported pregnancy history indicates the need to consider alternative sources.
• Findings support the hypothesis that only specific types of chimeric cells may persist in maternal circulation post-pregnancy.