RETNLB and obesity due to melanocortin 4 receptor deficiency: Upregulated expression of Retnla/Fizz1 and Folr2 genes in HFD macrophages (Figure 8C,D and Figure 9B) suggests that HFD-induced obesity stimulates the generation and/or recruiting of M2 macrophages in mammary glands, which is a sign of immunosuppression.