TLR5 and obesity due to melanocortin 4 receptor deficiency: Recently, our collaborators, Vijay-Kumar et al [24] reported that TLR5 deficient mice also developed obesity, hyperlipidemia, and insulin resistance in response to high fat diet and the transfer of gut microbiota from TLR5 deficient mice to WT-germ-free mice conferred obesity, hyperlipidemia, and insulin resistance (features of metabolic syndrome) to the recipients suggesting that the gut microbiota mediate metabolic derangements associated with high fat diet.