Mechanistic explanations how cell-mediated immune activation, inflammation and oxidative and nitrosative stress pathways and their sequels and concomitants play a role in the pathophysiology of unipolar depression

► Depression is accompanied by immune activation, inflammation and neuroprogression. ► Immune activation and inflammation may cause neuroprogression and depression. ► Sequels and concomitants of immune activation and inflammation play a key role in depression. ► Key players are: tryptophan and 5-HT, oxidative stress, antioxidants, omega-3, and leaky gut. ► Depression is the consequence of a complex interplay between these different pathways.