CCR5 and central nervous system cancer: M2 polarization was also induced by metabolites of glioma cells such as adenosine (Komohara et al., 2008; Kesarwani et al., 2019), along with the secretion of CSF-1 (Pyonteck et al., 2013), the expression of CCR5 (Laudati et al., 2017), and DNA damage repair (Meng et al., 2019) of glioma cells.