Use of knockout transgenic mice in the study of endometriosis: insights from mice lacking beta(2)-microglobulin and interleukin-12p40

Objective: To test the possibility of using transgenic knockout mice in the study of endometriosis and to investigate specific immunologic aspects of the disease. Design: Experimental blinded study. Setting: Academic research center. Animal(s): Thirty-two mice with experimentally induced endometriosis. Intervention(s): Endometriosis was induced in 8 beta (2)-microglobulin-deficient BALB/c mice and 7 wild-type BALB/c controls. Similarly, endometriosis was induced in 8 interleukin-12-deficient C57BL/6 mice and in 9 wild-type C57BL/6 controls. Main Outcome Measure(s): Weight and surface area of endometriotic lesions. Result(s): Total weight and surface area of endometriotic lesions was markedly lower in beta (2)-microglobulindeficient BALB/c mice than in wild-type BALB/c controls. A slight but statistically insignificant increase in total weight and surface area of lesions was observed in interleukin-12-deficient C57BL/6 mice compared to wild-type C57BL/6 controls. Conclusion(s): Knockout transgenic mice can be used successfully for the study of endometriosis; however, in these animals, the redundancy of the immunologic cytokine-mediated regulatory mechanisms may lead to compensation from the remaining genome. Results from beta (2)-microglobulin-deficient mice support the critical role of the immune system in the pathogenesis of the disease.