Toxicity of oral cadmium intake: Impact on gut immunity

• Examination of the effect of oral cadmium intake on gut immune responses in rat.
• Tissue damage and inflammation were evident in homogenates of duodenum.
• Cadmium intake primes adaptive immune activities of mesenteric lymph node cells.
• Innate immune activities of mesenteric lymph node cells were observed.
• Cadmium-induced gut immune activity depicts its significance as health risk factor.

Gastrointestinal tract is one of the main targets of cadmium (Cd), an important food and drinking water contaminant. In the present study, the effect of subchronic (30 days) oral (in water) intake of 5 ppm and 50 ppm of cadmium on immune responses in the gut was examined in rats. Cadmium consumption resulted in reduction of bacteria corresponding to Lactobacillus strain, tissue damage and intestinal inflammation [increases in high mobility group box 1 (HMGB1 molecules), superoxide dismutase (SOD) and catalase (CAT) activity and proinflammatory cytokine (TNF, IL-1β, IFN-γ, IL-17) content]. Draining (mesenteric) lymph node (MLN) stress response was observed [elevation of MLN glutathione (GSH) and metallothionein (MT) mRNA levels] and stimulation of both adaptive [cellularity, proliferation, proinflammatory (IFN-γ and IL-17) MLN cell cytokine responses] as well as innate immune activity (increases in numbers of NK and CD68+ cells, oxidative activities, IL-1β). In contrast to proinflammatory milieu in MLN, decreased or unchanged antiinflammatory IL-10 response was observed. Stimulation of immune activities of MLN cells have, most probably, resulted from sensing of cadmium-induced tissue injury, but also from bacterial antigens that breached compromised intestinal barrier. These effects of cadmium should be taken into account when assessing dietary cadmium as health risk factor.