Exploring the protective role of DDIT4/mTOR in podocyte integrity through macrophage polarization in diabetic kidney disease.

Objectives: In this study, we explored the mechanism by which DDIT4 influences the polarization phenotypic transformation of macrophages and inflammation through the regulation of mTOR signaling pathway, providing a new mechanism and target for the treatment of diabetic nephropathy.

Methods: The degree of inflammation and injury in renal tissues of diabetic kidney disease (DKD) animal model was evaluated using biochemical assays, renal pathology examinations, and Western blot tests. Podocytes and macrophages were isolated from renal tissues to observe the extent of podocyte injury and the quantity and polarization phenotype of macrophage infiltration. Subsequently, the activated M1 macrophage model was constructed and transfected with DDIT4 to evaluate the effect of DDIT4 on the polarization phenotype transformation of macrophages and the expression of inflammatory factors. Finally, the co-culture system of macrophages and podocytes was constructed to detect the cell apoptosis, and the morphology and subcellular structure of podocin were observed by transmission electron microscopy.

Results: In the DKD animal model, the expression levels of inflammatory factors in renal tissues were significantly higher than those in the control group. Additionally, there was significant damage to the renal podocytes. At the same time, there was a higher number of macrophage infiltrations, predominantly of the M1 polarized phenotype. In the constructed M1 polarized macrophage model, overexpression of DDIT4 can induce the decrease of M1 macrophages and reduce the expression level of inflammatory factors. In the co-culture system of macrophages and podocytes, overexpressed DDIT4 significantly reduced the proportion of podocyte apoptosis and protect the changes of morphology and subcellular structure.

Conclusions: The ability of DDIT4 to mediate the transformation of macrophage phenotype and reduce inflammation reveals its potential as an innovative drug discovery target for DKD. Further exploration and validation of the therapeutic potential of DDIT4 may provide effective interventions to address unaddressed clinical needs in the treatment of DKD.