No abstract

Bacteriophage therapy is currently resurging as a potential complement/alternative to antibiotic treatment. However, preclinical evaluation lacks streamlined approaches. We here focus on preclinical approaches which have been implemented to assess bacteriophage efficacy against Pseudomonas biofilms and infections. Laser interferometry and profilometry were applied to measure biofilm matrix permeability and surface geometry changes, respectively. These biophysical approaches were combined with an advanced Airway Surface Liquid infection model, which mimics in vitro the normal and CF lung environments, and an in vivo Galleria larvae model. These assays have been implemented to analyze KTN4 (279,593 bp dsDNA genome), a type-IV pili dependent, giant phage resembling phiKZ. Upon contact, KTN4 immediately disrupts the P. aeruginosa PAO1 biofilm and reduces pyocyanin and siderophore production. The gentamicin exclusion assay on NuLi-1 and CuFi-1 cell lines revealed the decrease of extracellular bacterial load between 4 and 7 logs and successfully prevents wild-type Pseudomonas internalization into CF epithelial cells. These properties and the significant rescue of Galleria larvae indicate that giant KTN4 phage is a suitable candidate for in vivo phage therapy evaluation for lung infection applications.

The estrogen sex steroid 17␤-estradiol rapidly inhibits secretagogue-stimulated cAMP-dependent Cl ؊ secretion in the female rat distal colonic crypt by the inhibition of basolateral K ؉ channels. In Ussing chamber studies, both the anti-secretory response and inhibition of basolateral K ؉ current was shown to be attenuated by pretreatment with rottlerin, a PKC␦-specific inhibitor. In whole cell patch-clamp analysis, 17␤-estradiol inhibited a chromanol 293B-sensitive KCNQ1 channel current in isolated female rat distal colonic crypts. Estrogen had no effect on KCNQ1 channel currents in colonic crypts isolated from male rats. Female distal colonic crypts expressed a significantly higher amount of PKC␦ in comparison to male tissue. PKC␦ and PKA were activated at 5 min in response to 17␤-estradiol in female distal colonic crypts only. Both PKC␦-and PKA-associated with the KCNQ1 channel in response to 17␤-estradiol in female distal colonic crypts, and no associations were observed in crypts from males. PKA activation, association with KCNQ1, and phosphorylation of the channel were regulated by PKC␦ as the responses were blocked by pretreatment with rottlerin. Taken together, our experiments have identified the molecular targets underlying the anti-secretory response to estrogen involving the inhibition of KCNQ1 channel activity via PKC␦-and PKA-dependent signaling pathways. This is a novel gender-specific mechanism of regulation of an ion channel by estrogen. The anti-secretory response described in this study provides molecular insights whereby estrogen causes fluid retention effects in the female during periods of high circulating plasma estrogen levels.