Development of a selective inhibitor for Kv1.1 channels prevalent in demyelinated nerves.

Members of the voltage-gated K+ channel subfamily (Kv1), involved in regulating transmission between neurons or to muscles, are associated with human diseases and, thus, putative targets for neurotherapeutics. This applies especially to those containing Kv1.1 α subunits which become prevalent in murine demyelinated axons and appear abnormally at inter-nodes, underlying the perturbed propagation of nerve signals. To overcome this dysfunction, akin to the consequential debilitation in multiple sclerosis (MS), small inhibitors were sought that are selective for the culpable hyper-polarising K+ currents. Herein, we report a new semi-podand - compound 3 - that was designed based on the modelling of its interactions with the extracellular pore region in a deduced Kv1.1 channel structure. After synthesis, purification, and structural characterisation, compound 3 was found to potently (IC50 = 8 µM) and selectively block Kv1.1 and 1.6 channels. The tested compound showed no apparent effect on native Nav and Cav channels expressed in F-11 cells. Compound 3 also extensively and selectively inhibited MS-related Kv1.1 homomer but not the brain native Kv1.1- or 1.6-containing channels. These collective findings highlight the therapeutic potential of compound 3 to block currents mediated by Kv1.1 channels enriched in demyelinated central neurons.

IL-8 released from human lung epithelial cells induced by cystic fibrosis pathogens Burkholderia cepacia complex affects the growth and intracellular survival of bacteria.

Burkholderia cepacia complex (Bcc) is a group of Gram-negative pulmonary pathogens associated with life-threatening infections in patients with cystic fibrosis (CF). The airway epithelium plays a crucial role in the initiation and modulation of inflammatory responses to these pathogens. Interleukin (IL)-8 released from epithelial cells is a potent chemoattractant for neutrophils. The aims of this study were to compare the IL-8 response to Bcc infection in different epithelial cell types and to investigate the impact of IL-8 on Bcc growth and intracellular survival. To compare epithelial cell IL-8 responses, 4 human epithelial cell lines were used in the study; A549 cells, an alveolar epithelial cell line, Calu-3 cells, a sub-bronchial epithelial cell line, 16HBE14o- cells, and CFBE41o- cells, which are CFTR-positive and CFTR-negative bronchial epithelial cell lines, respectively. Two B. multivorans and 2 B. cenocepacia strains all induced a significant IL-8 response by 12 h and further increased in all cell lines at 24 h. Furthermore, the levels of IL-8 from Calu-3 and A549 cells were approximately 3 times that of 16HBE14o- or CFBE41o- cells. In 2 of the cell lines examined (16HBE14o- and CFBE41o-), B. cenocepacia LMG 16656 (J2315), an epidemic strain, induced greater levels of IL-8 (P<0.01) compared to other Bcc strains tested. The CFTR-positive and -negative cell lines secreted similar levels of IL-8 indicating a CFTR-independent induction of IL-8. However, the CFTR-negative cells did secrete constitutive levels of IL-8 greater than that of CFTR-positive cells. An investigation of the effect of IL-8 on Bcc extracellular and intracellular growth found that at low concentrations (<10 ng/ml) of recombinant human (rh) IL-8, the growth of B. cenocepacia LMG 16656 and B. multivorans LMG 13010 was enhanced, whereas at higher concentrations (10 ng/ml), growth of both strains was significantly reduced. Growth of both non-CF Bcc strains remained unchanged in the presence of rhIL-8. In contrast to extracellular growth, higher concentrations (10ng/ml) of rhIL-8 enhance the intracellular growth and survival of both LMG 16656 and LMG 13010 in 16HBE14o- and CFBE41o- cell lines. Although LMG 13010 uptake by epithelial cells was higher than LMG 16656 (P<0.01), the intracellular growth of LMG 16656 is greater than LMG 13010 (P<0.05). These studies demonstrated that the type of epithelial cells encountered by Bcc strains determines the extent of the IL-8 responses triggered and that this cytokine in addition to its well-established proinflammatory properties can enhance both the extracellular and intracellular growth of Bcc strains.