The effects of interleukin-8 on airway smooth muscle contraction in cystic fibrosis

Background

Clara cells are the epithelial progenitor cell of the small airways, a location known to be important in many lung disorders. Although migration of alveolar type II and bronchiolar ciliated epithelial cells has been examined, the migratory response of Clara cells has received little attention.

Methods

Using a modification of existing procedures for Clara cell isolation, we examined mouse Clara cells and a mouse Clara-like cell line (C22) for adhesion to and migration toward matrix substrate gradients, to establish the nature and integrin dependence of migration in Clara cells.

Results

We observed that Clara cells adhere preferentially to fibronectin (Fn) and type I collagen (Col I) similar to previous reports. Migration of Clara cells can be directed by a fixed gradient of matrix substrates (haptotaxis). Migration of the C22 cell line was similar to the Clara cells so integrin dependence of migration was evaluated with this cell line. As determined by competition with an RGD containing-peptide, migration of C22 cells toward Fn and laminin (Lm) 511 (formerly laminin 10) was significantly RGD integrin dependent, but migration toward Col I was RGD integrin independent, suggesting that Clara cells utilize different receptors for these different matrices.

Conclusion

Thus, Clara cells resemble alveolar type II and bronchiolar ciliated epithelial cells by showing integrin mediated pro-migratory changes to extracellular matrix components that are present in tissues after injury.     

Fine-scale metabolic discontinuity in a stratified prokaryote microbiome of a Red Sea deep halocline

Deep-sea hypersaline anoxic basins are polyextreme environments in the ocean’s interior characterized by the high density of brines that prevents mixing with the overlaying seawater, generating sharp chemoclines and redoxclines up to tens of meters thick that host a high concentration of microbial communities. Yet, a fundamental understanding of how such pycnoclines shape microbial life and the associated biogeochemical processes at a fine scale, remains elusive. Here, we applied high-precision sampling of the brine–seawater transition interface in the Suakin Deep, located at 2770 m in the central Red Sea, to reveal previously undocumented fine-scale community structuring and succession of metabolic groups along a salinity gradient only 1 m thick. Metagenomic profiling at a 10-cm-scale resolution highlighted spatial organization of key metabolic pathways and corresponding microbial functional units, emphasizing the prominent role and significance of salinity and oxygen in shaping their ecology. Nitrogen cycling processes are especially affected by the redoxcline with ammonia oxidation processes being taxa and layers specific, highlighting also the presence of novel microorganisms, such as novel Thaumarchaeota and anammox, adapted to the changing conditions of the chemocline. The findings render the transition zone as a critical niche for nitrogen cycling, with complementary metabolic networks, in turn underscoring the biogeochemical complexity of deep-sea brines.Subject terms: Microbial ecology, Metagenomics     

Root bacterial endophytes confer drought resistance and enhance expression and activity of a vacuolar H+-pumping pyrophosphatase in pepper plants

It has been previously shown that the transgenic overexpression of the plant root vacuolar proton pumps H⁺-ATPase (V-ATPase) and H⁺-PPase (V-PPase) confer tolerance to drought. Since plant-root endophytic bacteria can also promote drought tolerance, we hypothesize that such promotion can be associated to the enhancement of the host vacuolar proton pumps expression and activity. To test this hypothesis, we selected two endophytic bacteria endowed with an array of in vitro plant growth promoting traits. Their genome sequences confirmed the presence of traits previously shown to confer drought resistance to plants, such as the synthesis of nitric oxide and of organic volatile organic compounds. We used the two strains on pepper (Capsicuum annuum L.) because of its high sensitivity to drought. Under drought conditions, both strains stimulated a larger root system and enhanced the leaves' photosynthetic activity. By testing the expression and activity of the vacuolar proton pumps, H⁺-ATPase (V-ATPase) and H⁺-PPase (V-PPase), we found that bacterial colonization enhanced V-PPase only. We conclude that the enhanced expression and activity of V-PPase can be favoured by the colonization of drought-tolerance-inducing bacterial endophytes.     

Synthesis and activity of quinolinyl-methylene-thiazolinones as potent and selective cyclin-dependent kinase 1 inhibitors

A novel series of quinolinyl-methylene-thiazolinones has been identified as potent and selective cyclin-dependent kinase 1 (CDK1) inhibitors. Their synthesis and structure activity relationships (SAR) are described. Representative compounds from this class reversibly inhibit CDK1 activity in vitro, and block cell cycle progression in human tumor cell lines, suggesting a potential use as antitumor agents.     

The pathophysiology of asthma

Because postmortem studies of humans provide little information on the initial pathophysiologic events in asthma, animal models have been developed. Recently the Ascaris-allergic rhesus monkey has provided an opportunity to examine the onset of pathophysiologic changes following challenge and to correlate them with airway structure. These studies have suggested that the initial interaction between antigen and mast cells may occur in the bronchial lumen or in the epithelium superficial to the tight junctions, where a small but significant percentage of airway mast cells exist. It also appears that this initial antigen-antibody interaction results in the release of mediators that both stimulate the rapidly adapting stretch receptors in the mucosa and alter the mucosal barrier so that proteins of large molecular weight can penetrate. The fact that antigen challenge results in hyperresponsiveness to a subsequent dose of inhaled histamine and increased systemic absorption of histamine suggests that the airway hyperresponsiveness could be related to increased penetration of histamine into the bronchial wall. These observations suggest that the initial event in an acute asthmatic attack is the release of mediators from superficial mast cells, and that this amplifies the allergic response by altering the mucosal permeability so that more antigen reaches the submucosal mast cells. This altered permeability may also help explain the hyperreactivity of the airways to nonspecific airway stimulants in persons with asthma.     

Interleukin-8: novel roles in human airway smooth muscle cell contraction and migration

In patients with cystic fibrosis (CF) and asthma, elevated levels of interleukin-8 (IL-8) are found in the airways. IL-8 is a CXC chemokine that is a chemoattractant for neutrophils through CXCR1 and CXCR2 G protein-coupled receptors. We hypothesized that IL-8 acts directly on airway smooth muscle cells (ASMC) in a way that may contribute to the enhanced airway responsiveness and airway remodeling observed in CF and asthma. The aim of this study was to determine whether human ASMC (HASMC) express functional IL-8 receptors (CXCR1 and CXCR2) linked to cell contraction and migration. Experiments were conducted on cells harvested from human lung specimens. Real-time PCR and fluorescence-activated cell sorting analysis showed that HASMC expressed mRNA and protein for both CXCR1 and CXCR2. Intracellular Ca²⁺ concentration ([Ca²⁺]_i) increased from 115 to 170 nM in response to IL-8 (100 nM) and decreased after inhibition of phospholipase C (PLC) with U-73122. On blocking the receptors with specific neutralizing antibodies, changes in [Ca²⁺]_i were abrogated. IL-8 also contracted the HASMC, decreasing the length of cells by 15%, and induced a 2.5-fold increase in migration. These results indicate that HASMC constitutively express functional CXCR1 and CXCR2 that mediate IL-8-triggered Ca²⁺ release, contraction, and migration. These data suggest a potential role for IL-8 in causing abnormal airway structure and function in asthma and CF. chemokines; lung; signal transduction     

Development of amino-pyrimidine inhibitors of c-Jun N-terminal kinase (JNK): Kinase profiling guided optimization of a 1,2,3-benzotriazole lead

A series of amino-pyrimidines was developed based upon an initial kinase cross-screening hit from a CDK2 program. Kinase profiling and structure-based drug design guided the optimization from the initial 1,2,3-benzotriazole hit to a potent and selective JNK inhibitor, compound 24f (JNK1 and 2 IC₅₀ = 16 and 66 nM, respectively), with bioavailability in rats and suitable for further in vivo pharmacological evaluation.