Interesting connections among recent science news articles. Cigarette smoking promotes lung aging by interfering with autophagy (cell component degradation and recycling) in lung cells and triggering apoptosis and cellular senescence. Similarly, here’s a paper showing that clearance of senescent cells rejuvenates lung tissue in mice. Senescent cells secrete a toxic mixture of molecules (the senescence-associated secretory phenotype), which – among other things – induces inflammation and the removal of senescent cells by the immune system. Tying together the previous two papers, here’s a recent Cell paper showing that defects of mitochondrial autophagy (mitophagy) promote inflammation and cell clearance by the immune system (here’s the pop-science version since the primary source is behind a paywall). Here are two questions: (1) Do similar defects in autophagy also lead to cellular senescence? (2) Autophagy (and mitophagy) increase following calorie restriction. Is part of the benefit of calorie restriction a decrease in inflammation due to this mechanism? And the long-standing big question of (3) why do senescent cells accumulate during the aging process? Is it from a decline of the immune system? Or is it something else?