UCP1 and obesity due to melanocortin 4 receptor deficiency: Similar to our observations showing that helminth infection results in a marked upregulation of UCP-1 expression, the results from our macrophage transfer experiments provide strong evidence that transfer of helminth-induced M2 cells, in the absence of helminths in the recipient host, is sufficient to induce an attenuated obesity and enhanced UCP-1 expression in adipose tissues, leading to the activation of browning in adipose tissue and the potential for enhanced thermogenesis.