CCL2 and periodontitis: Notably, MCP-1 upregulation is also observed in periodontitis patients at both the serum and tissue levels, with significantly elevated serum MCP-1 levels in periodontitis patients compared to healthy controls, as well as higher MCP-1 mRNA and protein expression in periodontitis tissues relative to controls (Gupta et al., 2013; Bostrom et al., 2015).