Airway mucus hyperproduction and fluid imbalance are important hallmarks of cystic fibrosis (CF), the most common life-shortening genetic disorder in Caucasians. Dysregulated expression and/or function of airway ion transporters, including cystic fibrosis transmembrane conductance regulator (CFTR) and epithelial sodium channel (ENaC), have been implicated as causes of CF-associated mucus hypersecretory phenotype. However, the contributory roles of other substances and transporters in the regulation of CF airway pathogenesis remain unelucidated. Here, we identified a novel connection between CFTR/ENaC expression and the intracellular Zn2 + concentration in the regulation of MUC5AC, a major secreted mucin that is highly expressed in CF airway. CFTR-defective and ENaC-hyperactive airway epithelial cells specifically and highly expressed a unique, alternative splice isoform of the zinc importer ZIP2/SLC39A2 (ΔC-ZIP2), which lacks the C-terminal domain. Importantly, ΔC-ZIP2 levels correlated inversely with wild-type ZIP2 and intracellular Zn2 + levels. Moreover, the splice switch to ΔC-ZIP2 as well as decreased expression of other ZIPs caused zinc deficiency, which is sufficient for induction of MUC5AC; while ΔC-ZIP2 expression per se induced ENaC expression and function. Thus, our findings demonstrate that the novel splicing switch contributes to CF lung pathology via the novel interplay of CFTR, ENaC, and ZIP2 transporters.

Background: Single immunoglobulin interleukin-1 receptor-related molecule (SIGIRR) is a negative inflammatory regulator whose regulatory mechanism is mainly described in epithelial tissues. Results: Higher monocytic and neutrophilic SIGIRR expression is maintained by Sp1. Conclusion: Lipopolysaccharide decreases SIGIRR expression by suppressing Sp1 via the TLR4-p38 pathway. Significance: The LPS-dependent SIGIRR down-regulation may be critical for optimal inflammatory responses in immune cells.

Cystic fibrosis (CF) is the most common lethal inherited disorder and is caused by mutations in the gene encoding the CF transmembrane regulator (CFTR). The CF lung expresses a profound proinflammatory phenotype that appears to be related to a constitutive hypersecretion of interleukin (IL)-8 from airway epithelial cells in response to microbial infection. Since overproduction of IL-8 in CF contributes to massive bronchial infiltrates of neutrophils, identification of the pathways underlying IL-8 induction could provide novel drug targets for treatment of neutro-phil-dominated inflammatory diseases such as CF. Here, we show that IL-17A synergistically increases IL-8 production induced by a toll-like receptor (TLR) 2 agonist, peptidoglycan (PGN), or TLR4 agonist, lipopolysaccharide (LPS), in a human CF bronchial epithelial cell line ( CFBE41o-). A strong synergism was also observed in primary human CF bronchial epithelial cells, but not in human non-CF cell lines and primary cells. Notably, despite the induction of nuclear factor-κB and MAP kinases during TLR2 or TLR4 activation in CFBE41o-, IL-17A-dependent synergism appears to be the result of enhanced PGN- or LPS-induced phosphorylation of p38. Taken together, these studies provide evidence that IL-17A is a critical factor in increasing IL-8 expression in bacteria-infected CF airways via a pathway that regulates p38 phosphorylation.

Cystic fibrosis (CF), the most common lethal inherited disorder caused by mutation in the gene encoding the CF transmembrane regulator (CFTR), is characterized by chronic inflammation that ultimately leads to death from respiratory failure. In CF patients, up-regulation of toll-like receptor-2 (TLR2), a pattern recognition receptor that senses CF-pathogenic bacteria Staphylococcus aureus peptidoglycan (PGN), in airway epithelial cells is observed, and enhanced proinflammatory responses towards PGN may result in detrimental effects in CF patients. Here, we showed that curcumin, a well known anti-inflammatory agent derived from the curry spice turmeric, inhibits TLR2 expression in CF bronchial epithelial cell line, CFBE41o-cells. Strong suppression of TLR2 gene and protein expression was observed at more than 40 µM of curcumin treatment in CFBE41o-cells. Consistent with decreased expression of TLR2, PGN-dependent interleukin-8 (IL-8) gene up-regulation was markedly reduced by 40 µM of curcumin treatment. Strong reductions of TLR2 gene expression and function were also observed in primary human CF bronchial epithelial cells, but not in human non-CF primary cells. Interestingly, curcumin treatment decreased nuclear expression of transcription factor specificity protein 1 (SP1), a factor that is critical for increased basal TLR2 expression in CF cell line and primary cells. Finally, curcumin-dependent SP1 reduction was diminished by anti-oxidant N-acetylcystein (NAC) and proteasomal inhibitor MG-132, suggesting the crucial roles of oxidative and proteasomal degradation pathways. Taken together, our study shows that curcumin down-regulates TLR2 gene expression and function in CF bronchial epithelial cells possibly by accelerating SP1 degradation via an oxidative process.

The oxidant/antioxidant imbalance plays a pivotal role in the lung. Uric acid (UA), an endogenous antioxidant, is highly present in lung tissue, however, its impact on lung function under pathophysiological conditions remains unknown. In this work, pharmacological and genetic inhibition of UA metabolism in experimental mouse models of acute and chronic obstructive pulmonary disease (COPD) revealed that increased plasma UA levels improved emphysematous phenotype and lung dysfunction in accordance with reduced oxidative stress specifically in female but not in male mice, despite no impact of plasma UA induction on the pulmonary phenotypes in nondiseased mice. In vitro experiments determined that UA significantly suppressed hydrogen peroxide (H2O2)-induced oxidative stress in female donor-derived primary human bronchial epithelial (NHBE) cells in the absence of estrogen, implying that the benefit of UA is limited to the female airway in postmenopausal conditions. Consistently, our clinical observational analyses confirmed that higher blood UA levels, as well as the SLC2A9/GLUT9 rs11722228 T/T genotype, were associated with higher lung function in elderly human females. Together, our findings provide the first unique evidence that higher blood UA is a protective factor against the pathological decline of lung function in female mice, and possibly against aging-associated physiological decline in human females.