TLR9 and obesity due to melanocortin 4 receptor deficiency: To investigate the role of B cell-TLR9 in obesity, we generated B cell-specific Tlr9-deficient C57BL/6 mice (Tlr9fl/fl/Cd19Cre+/-B6), and studied both Tlr9fl/fl/Cd19Cre+/- B6 mice (designated as KO group) and Tlr9fl/fl/Cd19Cre-/- B6 littermate controls (designated as Ctr group).