TNF and Alzheimer disease: After eight weeks of exposure to PM2.5 at 61 μg/m3 (which represented 80% of the atmospheric concentration of 87 μg/m3) AD-mice had increased pro-inflammatory cytokine concentrations (i.e., tumor necrosis factor-alpha [TNF-a] and interleukin [IL-6]) in the brain and intestines alongside altered microbial diversity in the intestine and feces compared to two control groups (AD-mice and B6 mice exposed to filtered air) [41].