Comparison of Two Mice Strains, A/J and C57BL/6, in Caspase-1 Activity and IL-1βSecretion of Macrophage toMycobacterium lepraeInfection

A/J mice were found to have amino acid differences in Naip5, one of the NOD-like receptors (NLRs) involved in the cytosolic recognition of pathogen-associated molecular patterns and one of the adaptor proteins for caspase-1 activation. This defect was associated with a susceptibility to Legionella infection, suggesting an important role for Naip5 in the immune response also to other intracellular pathogens, such as Mycobacterium leprae . In this study, the immune responses of macrophages from A/J mice against M. leprae were compared to those of macrophages from C57BL/6 mice. Infection with M. leprae induced high levels of TNF- α production and NF- κ B activation in A/J and C57BL/6 macrophages. Caspase-1 activation and IL-1 β secretion were also induced in both macrophages. However, macrophages from A/J mice exhibited reduced caspase-1 activation and IL-1 β secretion compared to C57BL/6 macrophages. These results suggest that NLR family proteins may have a role in the innate immune response to M. leprae .