Protective Effects Of Trehalose On Cadmium-induced Spleen Damage In Rats

Cadmium(Cd)is a ubiquitous and highly toxic heavy metal contaminant that accumulates in the body and causes damage to tissues and organs.The damage of Cd to the body is multi-systemic and multi-organic,including immune organs.The toxicity mechanism of Cd on tissue cells is closely related to oxidative stress.Trehalose(Tre)is a non-reducing disaccharide,which acts as an autophagy promoter has both anti-oxidation and anti-apoptosis effects.However,the mechanism of Tre antagonizes the cytotoxicity induced by Cd has not been elucidated.Therefore,this study established a rat poisoning model through take cadmium chloride as drinking water,and used Tre as a protective agent to investigate the protective effect of Tre on Cd-induced spleen injury from three aspects of oxidative stress,autophagy,and apoptosis.Firstly,HE staining of spleen tissue paraffin sections showed that Tre could significantly improve the pathological damage of spleen caused by Cd under light microscope,indicating that Tre has protective effect on spleen damage caused by Cd.Secondly,oxidative stress related indicators in spleen tissue homogenate were detected,including T-AOC and MDA.The results indicate that Cd can cause oxidative stress in spleen tissue.Tre as an antioxidant can alleviate oxidative stress.This shows that Tre can up-regulate the level of T-AOC and reduce the production of lipid peroxide MDA in spleen.Nrf2-Keap1 signaling pathway is an important oxidative stress defense mechanism in cells.We further explored the relationship between Tre alleviated Cd-induced oxidative stress and Nrf2 signaling pathway in spleen.Normal activation of Nrf2 signaling pathway can protect cells from oxidative stress,but continuous activation of Nrf2 signaling pathway caused by long-term low-dose Cd exposure will aggravate oxidative stress.After the addition of Tre,we found that reduced of Nrf2 nuclear level and decreased expression of Nrf2 downstream target protein,indicating that Tre can inhibit Cd-induced Nrf2 signaling pathway activation.The above analysis shows that Tre has the effect of alleviating oxidative stress induced by Cd in the spleen and plays a role by inhibiting the continuous activation of the Nrf2 signalingpathway.Third,studies has shown that Cd can cause autophagy inhibition in spleen cells,so we investigated the effect of Tre on autophagy inhibition induced by Cd in spleen cells.As an inducer of autophagy,Tre showed that Tre can significantly regulated the levels of autophagy marker proteins p62 and LC3,and alleviate the inhibition of autophagy in spleen cells induced by Cd.Not only can p62 be used as an autophagic substrate to determine autophagy activity,but also participate in the activation of Nrf2-Keap1 signaling pathway.Accumulation of p62 activates Nrf2 expression;in turn,Nrf2 entry into the nucleus leads to an increase in p62 mRNA levels.It can be seen that Nrf2 is inseparable from autophagy inhibition during the process of Tre promoting autophagy.Fourth,oxidative stress and autophagy inhibition aggravated Cd-induced cell apoptosis.The TUNEL results show that Tre has a protective effect.In addition,Cd increased the levels of the apoptotic proteins Bax and Cleaved PARP and decreased the expression of the apoptosis inhibitory protein Bcl-2 after the addition of Tre also indicated that Tre can alleviate the apoptosis of spleen cells induced by Cd.In conclusion,Tre antagonizes Cd-induced oxidative stress in spleen by regulating Nrf2 signaling pathway,and counteracts Cd-induced spleen damage by relieving autophagy inhibition and apoptosis,providing potential treatment strategy for Cd-induced immune system diseases.