Insights on inflammatory pathways and their cross-talk: a comprehensive review on asthma

Allergic asthma is a heterogeneous respiratory disease characterized by recurring chest tightness, wheezing, coughing, and shortness of breath. Inflammation in asthma can be characterized into two types: T2 inflammation (Eosinophilic asthma) and non-T2 inflammation (Neutrophilic asthma). T2 inflammation is mediated by T helper type 2 cells (Th2) And innate lymphoid type 2 cells (ILC2), whereas the involvement of neutrophils, macrophages, and cytokines such as IL-2, IL-6, and IL-17 characterizes non-T2 inflammation. Asthma pathophysiology is complexly linked to the dysregulation of key intracellular signaling pathways, including NF-κB, JAK-STAT, MAPK, PI3K, and Nrf2. NF-κB plays an important role in the maintenance of the chronic inflammatory response by increased expression of cytokines in the airway epithelium. In contrast, the MAPK signaling pathway, through the involvement of MAPKs, which belong to the family of serine/threonine protein kinases, contributes to inflammatory responses through responding to various stimuli such as osmotic stress, heat shock, mitogens, and the inflammatory cytokines, which result in the regulation of cell proliferation, cell survival, cell differentiation, and apoptosis. JAK-STAT signaling mediates cytokine responses critical for Th2-driven asthma phenotypes, while the PI3K pathway exacerbates inflammation and oxidative stress through several processes, e.g., cell growth, proliferation, survival, differentiation, and migration. Conversely, the Nrf2 pathway is a protective mechanism, regulating antioxidant defenses to counter oxidative damage in asthmatic airways. Exploring the interesting crosstalk between these pathways offers profound insights into asthma's intricate molecular mechanisms, thereby paving the way for targeted and personalized therapeutic interventions.