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High molybdenum (Mo) and cadmium (Cd) are harmful to the body, but pulmonary toxicity induced by Mo and Cd co‐exposure is unknown. To assess the combined impacts of Mo and Cd on fibrosis through M1 polarization in the lung of ducks, 80 healthy 8‐day‐old Shaoxing ducks (Anas platyrhyncha) were randomly assigned to 4 groups and fed with containing unequal doses of Mo or/and Cd diet. Lung tissues were collected on the 16th week. Results indicated that Mo or/and Cd significantly increased their contents in the lungs, and led to trace elements disorder and histological abnormality, and oxidative stress accompanied by promoting contents of H2O2 and MDA and decreasing activities of T‐SOD, GSH‐Px, and CAT, then activated the TLR4/NF‐κB/NLRP3 pathway accompanied by upregulating Caspase‐1, ASC, IL‐18, IL‐1β, TLR4, NF‐κB, and NLRP3 expression levels, and disrupted M1/M2 balance to divert toward M1, which evoked the TGF‐β/Smad2/3‐mediated fibrosis by elevating TGF‐β1, Smad2, Smad3, COL1A1, α‐SMA, and MMP2 expression levels, and decreasing Smad7 and TIMP2 expression levels. The changes of the combined group were most obvious. To sum up, the research demonstrated that Mo or/and Cd may cause macrophages to polarize toward M1 by oxidative stress‐mediated the TLR4/NF‐κB/NLRP3 pathway, then result in fibrosis through the TGF‐β1/Smad2/3 pathway in duck lungs. Mo and Cd may worsen lung damage.

Cadmium (Cd) is detrimental to animals, but nephrotoxic effects of Cd on duck have not been fully elucidated. To evaluate the impacts of Cd on Ca homeostasis and autophagy via PLC-IP 3 -IP 3 R pathway, primary duck renal tubular epithelial cells were exposed to 2.5 μM and 5.0 μM Cd, and combination of 5.0 μM Cd and 10.0 μM 2-APB or 0.125 μM U-73122 for 12 h (U-73122 pretreated for 1 h). These results evidenced that Cd induced [Ca 2+ ] c overload mainly came from intracellular Ca store. Cd caused [Ca 2+ ] mit and [Ca 2+ ] c overload with [Ca 2+ ] ER decrease, elevated Ca homeostasis related factors (GRP78, GRP94, CRT, CaN, CaMKII, and CaMKKβ) expression, PLC and IP 3 activities and IP 3 R expression, but subcellular Ca 2+ redistribution was reversed by 2-APB. PLC inhibitor U-73122 dramatically relieved the changes of the above indicators induced by Cd. Additionally, U-73122 obviously reduced the number of autophagosomes and LC3 accumulation spots, Atg5, LC3A, LC3B mRNA levels and LC3II/LC3I, Beclin-1 protein levels induced by Cd, and markedly elevated p62 mRNA and protein levels. Overall, the results verified that Cd induced [Ca 2+ ] c overload mainly originated from ER Ca 2+ release mediated by PLC-IP 3 -IP 3 R pathway, then triggered autophagy in duck renal tubular epithelial cells.