Molybdenum And Cadmium Combined Exposure Induces Pulmonary Tissue Injury By Activating TGF-β/Smad2/3 Signaling Pathway In Ducks

In order to explore the combined effects of Mo and Cd on lung injury of ducks,40healthy Shaoxing ducks aged 8 days were randomly divided into four groups,and Mo and Cd（mg/kg）were added to the basal diet:Control group,Mo group（100 mg Mo）,Cd group（4 mg Cd）and Mo+Cd group（100 mg Mo+4 mg Cd）.Lung tissues were collected on the 16^thweek.H&E staining,Masson staining,ELISA,RT-q PCR and western blotting were used to analyze the pathological changes of lung tissue and detect the content of trace elements,oxidative stress level,inflammation-related factors and fibrosis related indicators.The results are as follows:1.Mo or/and Cd significantly increased the contents of Mo and Cd and significantly reduced the contents of Zn,Cu and Fe in lung tissue,and the lung tissue showed obvious bleeding,vacuolation,interstitial widening,inflammatory cell infiltration,and diffuse collagen hyperplasia,The above changes were most obvious in Mo+Cd group,The results indicated that Mo,Cd and their combined exposure could cause the damage of trace elements and lung tissue in duck.2.Mo or/and Cd significantly increased the content of H₂O₂and MDA,significantly decreased the activities of T-SOD,GSH,GSH-Px and CAT in lung tissue,The above changes were most obvious in Mo+Cd group,The results indicated that Mo,Cd and their combined exposure induced oxidative stress in duck lung tissue.3.Mo or/and Cd significantly upregulated Caspase-1,ASC,IL-18,IL-1β,TLR4,NF-κB,NLRP3,TGF-β1,Smad2,Smad3,COL1A1,α-SMA and MMP2 expression levels,significantly decreased Smad7 and TIMP2 expression levels,The above changes were most obvious in Mo and Cd combined group,The results indicated that Mo,Cd and their combined exposure induced inflammatory reaction in duck lung,which eventually led to fibrosis.To sum up,the research demonstrated that Mo or/and Cd may cause macrophages to polarize toward M1 by oxidative stress-mediated inflammatory reaction,then result in fibrosis through the TGF-β1/Smad2/3 pathway in duck lungs.Cobmined exposure of Mo and Cd may worsen duck lung damage.