| Macrophages are innate immune cells that are widely distributed in various tissues and organs and their function can change with disease progression.The stiffness of the tissue microenvironment also changes during disease progression.However,studies on the effect of stromal stiffness on macrophage function are still imperfect.Although,mitochondria can be involved in regulating the immune response of macrophages,whether altered mitochondrial dynamics,affect the inflammatory response of macrophages is not known.Therefore,the present study is centered on the mechanism by which matrix stiffness regulates the inflammatory response of macrophages through mitochondrial dynamics,providing a new perspective on targeting macrophages for the treatment of inflammatory diseases.We first observed in vivo in mice that altering tumor tissue stiffness affects macrophage polarization phenotype and systemic inflammation.To investigate the mechanism by which stiffness affects the inflammatory response of macrophages,we constructed 2D culture systems of cells with both soft and stiff stiffness in vitro using polyacrylamide hydrogels.Through observation of macrophage morphology and detection of macrophage polarization by ELISA,q PCR and flow cytometry,it was found that the soft substrate could resist the ability of macrophages to switch to a proinflammatory phenotype.Subsequently,observation of mitochondrial morphology revealed that macrophages grown on softer hydrogels had longer mitochondrial lengths,more pronounced mitochondrial network-like structure formation,higher levels of mitochondrial membrane potential,and lower expression of division-related proteins.Compared to soft hydrogels,mitochondrial length was shorter and the increase in mitochondrial length was significantly greater on high stiffness hydrogels after reducing DRP-1 expression.Suggesting that mitochondrial division may be involved in the inflammatory response of macrophages regulated by matrix stiffness.We used ELISA assays and q PCR assays to then examine the levels of pro-inflammatory and antiinflammatory factors.It was found that the expression of anti-inflammatory factors increased after knockdown of DRP-1,and the increase was more pronounced on stiffer hydrogels.In summary,matrix stiffness can affect the morphology and function of mitochondria in macrophages,in addition to the morphology of macrophages and their response to inflammation.And matrix stiffness can affect the macrophage response to inflammation by controlling the mitochondrial fission.Finally,the effect of altered mitochondrial morphology in macrophages,on their inflammatory response,was explored in mice.The results revealed that mitochondrial morphology can alter the polarization of macrophages and affect the macrophage response to inflammation.Inhibition of mitochondrial division of macrophages promotes tumor metastasis in mice.Thus,matrix stiffness was found to regulate the inflammatory response of macrophages,in which mitochondrial dynamics plays an important role.This enriches our understanding of mitochondrial morphology in immune cells and provides new perspectives for the treatment of diseases.and provided a new perspective for treating diseases by altering macrophage function. |
