Treatment with epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) improves the overall survival of patients with EGFR-mutated non-small-cell lung cancer (NSCLC). First-generation EGFR-TKIs (e.g., gefitinib and erlotinib) or second-generation EGFR-TKIs (e.g., afatinib and dacomitinib) are effective for the treatment of EGFR-mutated NSCLC, especially in patients with EGFR exon 19 deletions or an exon 21 L858R mutation. However, almost all cases experience disease recurrence after 1 to 2 years due to acquired resistance. The EGFR T790M mutation in exon 20 is the most frequent alteration associated with the development of acquired resistance. Osimertinib—a third-generation EGFR-TKI—targets the T790M mutation and has demonstrated high efficacy against EGFR-mutated lung cancer. However, the development of acquired resistance to third-generation EGFR-TKI, involving the cysteine residue at codon 797 mutation, has been observed. Other mechanisms of acquired resistance include the activation of alternative pathways or downstream targets and histological transformation (i.e., epithelial–mesenchymal transition or conversion to small-cell lung cancer). Furthermore, the development of primary resistance through overexpression of the hepatocyte growth factor and suppression of Bcl-2-like protein 11 expression may lead to problems. In this report, we review these mechanisms and discuss therapeutic strategies to overcome resistance to EGFR-TKIs.

Adenosine is involved in a range of physiological and pathological effects through membrane-bound receptors linked to G proteins. There are four subtypes of adenosine receptors, described as A₁AR, A_2AAR, A_2BAR, and A₃AR, which are the center of cAMP signal pathway-based drug development. Several types of agonists, partial agonists or antagonists, and allosteric substances have been synthesized from these receptors as new therapeutic drug candidates. Research efforts surrounding A₁AR and A_2AAR are perhaps the most enticing because of their concentration and affinity; however, as a consequence of distressing conditions, both A_2BAR and A₃AR levels might accumulate. This review focuses on the biological features of each adenosine receptor as the basis of ligand production and describes clinical studies of adenosine receptor-associated pharmaceuticals in human diseases.

In this study, we determined whether the proinflammatory cytokines tumor necrosis factor (TNF)-α and interleukin-1β contribute to the regulation of matrix metalloproteinase (MMP)-9 in human bronchial epithelial cells and whether the induction of MMP-9 is regulated by the transcription factor nuclear factor (NF)-κB. We demonstrated that TNF-α induced MMP-9 at both the protein and mRNA levels in human bronchial epithelial cells and that interleukin-1β did not. In contrast, induction of the tissue inhibitor of metalloproteinase-1 by TNF-α was less than that of interleukin-1β. Increased expression of MMP-9 and NF-κB activation induced by TNF-α were inhibited by pyrrolidine dithiocarbamate andN-acetyl-l-cysteine but were not inhibited by curcumin. These results suggest that TNF-α induces the expression of MMP-9 in human bronchial epithelial cells and that this induction is mediated via the NF-κB-mediated pathway.

Although mechanical ventilation (MV) is an important supportive strategy for patients with acute respiratory distress syndrome, MV itself can cause a type of acute lung damage termed ventilator-induced lung injury (VILI). Because nitric oxide (NO) has been reported to play roles in the pathogenesis of acute lung injury, the present study explores the effects on VILI of NO derived from chronically overexpressed endothelial nitric oxide synthase (eNOS). Anesthetized eNOS-transgenic (Tg) and wild-type (WT) C57BL/6 mice were ventilated at high or low tidal volume (Vt; 20 or 7 ml/kg, respectively) for 4 h. After MV, lung damage, including neutrophil infiltration, water leakage, and cytokine concentration in bronchoalveolar lavage fluid (BALF) and plasma, was evaluated. Some mice were given N^ω-nitro-l-arginine methyl ester (l-NAME), a potent NOS inhibitor, via drinking water (1 mg/ml) for 1 wk before MV. Histological analysis revealed that high Vt ventilation caused severe VILI, whereas low Vt ventilation caused minimal VILI. Under high Vt conditions, neutrophil infiltration and lung water content were significantly attenuated in eNOS-Tg mice compared with WT animals. The concentrations of macrophage inflammatory protein-2 in BALF and plasma, as well as plasma tumor necrosis factor-α and monocyte chemoattractant protein-1, also were decreased in eNOS-Tg mice. l-NAME abrogated the beneficial effect of eNOS overexpression. In conclusion, chronic eNOS overexpression may protect the lung from VILI by inhibiting the production of inflammatory chemokines and cytokines that are associated with neutrophil infiltration into the air space.

Asthma is an important issue not only in health but also in economics worldwide. Therefore, asthma animal models have been frequently used to understand the pathogenesis of asthma. Recently, in addition to acquired immunity, innate immunity has also been thought to be involved in asthma. Among innate immune cells, group 2 innate lymphoid cells (ILC2s) have been considered to be crucial for eosinophilic airway inflammation by releasing T helper 2 cytokines. Moreover, house dust mites (HDMs) belonging to group 1 act on airway epithelial cells not only as allergens but also as cysteine proteases. The production of interleukin-25 (IL-25), IL-33, and thymic stromal lymphopoietin (TSLP) from airway epithelial cells was induced by the protease activity of HDMs. These cytokines activate ILC2s, and activated ILC2s produce IL-5, IL-9, IL-13, and amphiregulin. Hence, the HDM-induced asthma mouse model greatly contributes to understanding asthma pathogenesis. In this review, we highlight the relationship between ILC2s and the HDM in the asthma mouse model to help researchers and clinicians not only choose a proper asthma mouse model but also to understand the molecular mechanisms underlying HDM-induced asthma.