Leukotrienes: Bridging the Inflammatory Gap in Asthma and Inflammatory Bowel Diseases (IBD)

Leukotrienes are potent inflammatory lipid mediators produced primarily by immune cells. Inflammation, being the center stone of two major disease conditions, namely, asthma and inflammatory bowel disease (IBD), has led researchers to study the role of leukotrienes (LTs) in both these disease settings extensively. Several studies indicate a crucial role for LTs in the development and progression of IBD, whereas LTs, especially cysteinyl leukotrienes (cys-LTs), have been identified as the major contributors to asthma initiation and progression for over three decades. Additionally, the lungs and the gut share several common characteristics, including their exposure to the external environment, similar microbiome composition, and inflammatory responses. These similarities suggest a bidirectional relationship, supported by the increased risk of IBD in asthma patients and vice versa. However, the specific role of LTs in this lung-gut connection remains unclear. This review will examine how several common factors, such as physiology, microbiome, environment, and inflammatory mediators, especially LTs, modulate this crosstalk. The review also highlights in detail how altered leukotriene biosynthesis and signaling contribute to the pathogenesis of both asthma and IBD. Furthermore, we will consider the therapeutic implications of targeting leukotriene pathways for patients with concurrent asthma and IBD in the hope of developing more efficient treatment outcomes for these interconnected conditions. Finally, this review will very briefly explore the involvement of neuronal connections in mediating the lung-gut crosstalk.