IL6 and bacterial infectious disease: Macrophages polarize to M1 response to kill the invading pathogens (such as Salmonella typhi, Salmonella typhimurium, and Mycobacterium tuberculosis, etc.)by the production of various proinflammatory cytokines including TNF-α, IL-6, and IL-1β in the early stage of bacterial infection (Sica and Mantovani, 2012; Liu et al., 2014).