Pro-apoptotic agents such as ligands and agonists of agonistic TRAIL receptors can induce or increase apoptosis of cells that cause fibrosis and underlying diseases such as liver, pancreatic, lung and skin diseases characterized by fibrosis, cirrhosis, or complications thereof. The compositions and methods can be used to selectively remove activated hepatic stellate cells (HSCs), the originators of liver fibrosis and cirrhosis, and activated pancreatic stellate cells (PSCs), the originators of pancreas fibrosis and pancreatitis, and can be effective to reduce or prevent further chronic fibrosis by simultaneously reducing multiple fibrosis-associated molecules secreted or induced by such activated stellate cells. The compositions are typically effective to target agonistic TRAIL receptors such as TRAIL-R1 / DR4 and TRAIL-R2 / DR5 that are selectively expressed in activated HSCs and PSCs in physiological conditions. Ligands and agonists that can be used to target agonistic TRAIL receptors include, but are not limited to, TRAIL-R1 / DR4 and / or TRAIL-R2 / DR5 agonists.