Accordingly, in vivo experiments have confirmed that obesity can affect the function and number of CD8+ immune cells through the related STAT3 pathway, metabolite GATM and ACSBG1 gene (Ringel et al., 2020; Zhang et al., 2020; Maguire et al., 2021). Here, ACSBG1 is linked to obesity due to melanocortin 4 receptor deficiency.