Clearing the Haze: How Does Nicotine Affect Hematopoiesis before and after Birth?

Simple Summary E-cigarettes have gained popularity as alternatives to traditional tobacco products over the past several decades. Despite being marketed as safer, they still contain several highly toxic compounds, which pose as dangers to human health. Nicotine is one of those toxic compounds and is known to have many deleterious effects on human health and disease susceptibility. Hematopoietic stem cells (HSCs) are the stem cells that give rise to the entire immune system and therefore serve as a compelling point of interrogation for the source of altered health and disease susceptibility in exposed individuals. Here we discuss how nicotine influences HSCs and the immune cells they make, as well as highlight potential mechanisms of altered immunity for life. Abstract Hematopoiesis is a tightly regulated process orchestrated by cell-intrinsic and cell-extrinsic cues. Over the past several decades, much effort has been focused on understanding how these cues regulate hematopoietic stem cell (HSC) function. Many endogenous key regulators of hematopoiesis have been identified and extensively characterized. Less is known about the mechanisms of long-term effects of environmental toxic compounds on hematopoietic stem and progenitor cells (HSPCs) and their mature immune cell progeny. Research over the past several decades has demonstrated that tobacco products are extremely toxic and pose huge risks to human health by causing diseases like cancer, respiratory illnesses, strokes, and more. Recently, electronic cigarettes have been promoted as a safer alternative to traditional tobacco products and have become increasingly popular among younger generations. Nicotine, the highly toxic compound found in many traditional tobacco products, is also found in most electronic cigarettes, calling into question their purported “safety”. Although it is known that nicotine is toxic, the pathophysiology of disease in exposed people remains under investigation. One plausible contributor to altered disease susceptibility is altered hematopoiesis and associated immune dysfunction. In this review, we focus on research that has addressed how HSCs and mature blood cells respond to nicotine, as well as identify remaining questions.