Is cystic fibrosis a TH17 disease?

Cystic Fibrosis (CF) is the most common lethal genetic disease in the Caucasian population and typically results in the development of bronchial inflammation, bronchiectasis, the progressive loss of lung function and ultimately death. Recently it has been shown that products of the Th(17) subset of T-cells, specifically, IL-17A and IL-17F are elevated in the sputum of CF patients. This review will go over experimental evidence supporting a role for the IL- 23/IL-17 axis in CF lung inflammation.

Effects of protein-polyelectrolyte affinity and polyelectrolyte molecular weight on dynamic properties of bovine serum albumin-poly(diallyldimethylammonium chloride) coacervates.

Bovine serum albumin (BSA) and poly(diallyldimethylammonium chloride) (PDADMAC) spontaneously form, over a range of ionic strength I and pH, dense fluids rich in both macroions. To study their nanostructure, these coacervates were prepared at low I and high pH (strong interaction) or at high I and lower pH (weaker interaction), with polymer MWs ranging from 90K to 700K, and then examined by dynamic light scattering (DLS) and rheology. DLS shows a dominant and surprisingly fast protein diffusional mode independent of polymer MW; accompanied by robust slow modes, slower by 1-2 orders of magnitude, which are also insensitive to MW and are present regardless of I, pH, and sample aging. High MW sensitivity was observed by rheology for the terminal time (order of milliseconds), which increased as well with the strength of polyelectrolyte-protein interaction. Viscoelastic behavior also indicated a tenuous network, solidlike at low strain but re-forming after breakage by shear. Two models, both of which have strengths and defects, are put forward: (I) macroion-rich domains dispersed in a continuum of macroion-poor domains near the percolation limit and (II) a semidilute solution of PDADMAC chains with interchain friction modulated by transient BSA-PDADMAC association.

Small-angle neutron scattering studies of charged carboxyl-terminated dendrimers in solutions.

Small-angle neutron scattering was used to characterize the solution behavior of charged carboxylic acid terminated "cascade" dendrimers (Z-Cascade/methane [4]/3-oxo-6-oxa-2-azaheptylidyne/3-oxo-2-azaheptylidyne/propanoic acids) of third (G3) and fifth (G5) generations as a function of dendrimer concentration, pH, and ionic strength. An increase in dendrimer concentration leads to a single broad peak in the scattering profile arising from interdendrimer interaction. The dissociation of terminal carboxylate groups also gives rise to an interdendrimer interaction peak, which could be suppressed by the addition of excess salt. The results of contrast matching measurements indicate the accumulation of an excess concentration of tetramethylammonium counterions around the surface of these highly charged particles, and the thickness of these counterions lies somewhere between 4 and 6 A. This conclusion is consistent with our previous potentiometric titration (Zhang, H.; et al. J. Phys. Chem. B 1997, 101, 3494) and capillary electrophoresis (Huang, Q. R.; et al. J. Phys. Chem. B 2000, 104, 898) data.

Determination of molecular weight of heparin by size exclusion chromatography with universal calibration.

The molecular weight (MW) of heparin can be accurately determined by size exclusion chromatography using "universal calibration." A universal calibration curve was constructed for Superose 12 with standard pullulan samples and verified using characterized ficoll fractions. This calibration yielded the correct MW of heparin as determined by light scattering, when the ionic strength of the mobile phase was maintained over 1.0M. Sodium poly(styrenesulfonate) samples were not suitable standards because of adsorption at high salt concentration and repulsion from the packing material at low ionic strength. The extraordinarily high charge density of heparin leads to the need for high salt concentration to screen such repulsions.

Identification by integrated computer modeling and light scattering studies of an electrostatic serum albumin-hyaluronic acid binding site.

Dynamic light scattering and turbidimetry, carried out on solutions of hyaluronic acid (HA) and bovine or human serum albumin (SA) at fixed ionic strength (I), revealed a critical pH corresponding to the onset of HA-SA soluble complex formation. Subsequent reduction of pH below pH(c), corresponding to an increase in protein net positive charge, results in phase separation of the complex. The sensitivity of pH(c) to I indicated the primacy of electrostatic interactions in this process. Since pH(c) was always above the pK(a) of HA, these effects could be attributed to the influence of protein charge. The electrostatic potential around HSA was modeled using DelPhi (MSI) under pH, I conditions corresponding to incipient binding, phase separation, and noninteraction. At all incipient binding conditions (i.e., pH(c), at varying I), an identical region of positive potential 5 A from the protein van der Waals surface appeared. This unique domain intensified with a decrease in pH or I (corresponding to stronger binding), and diminished with an increase in pH or I (i.e., at noninteracting conditions). The size and low curvature of this domain could readily accommodate a 12 nm (decamer) sequence of HA. Simple electrostatic considerations indicate an electrostatic binding energy for the formation of this complex of ca. 1 kT, consistent with the condition of incipient complex formation. We suggest that such weak electrostatic binding may characterize nonspecific interactions for other protein-gylcosaminoglycan pairs.

Binding of bovine serum albumin to heparin determined by turbidimetric titration and frontal analysis continuous capillary electrophoresis.

The association of proteins with glycosaminoglycans is a subject of growing interest, but few techniques exist for elucidating this interaction quantitatively. Here we demonstrate the application of capillary electrophoresis to the system of serum albumin (SA) and heparin (Hp). These two species form soluble complexes, the interaction increasing with reduction in pH and/or ionic strength (I). The acid-base property of Hp was characterized by potentiometric titration of ion-exchanged Hp. Conditions for complex formation with SA were qualitatively determined by turbidimetry, which revealed points of incipient binding (pH(c)) and phase separation (pH(phi)), both of which depend on I. At pH > pH(phi), i.e., prior to phase separation, frontal analysis continuous capillary electrophoresis was used to measure the concentration of free protein and to determine the protein-HP binding isotherm. The binding isotherms were well fit by the McGhee-von Hippel model to yield quantitative binding information in the form of intrinsic binding constants (K(obs)) and binding site size (n). The strong increase in K(obs) with decrease of pH or I could be explained on the basis of electrostatic interactions, considering the effects of protein charge heterogeneity. The value of n, independent of pH, was rationalized on the basis of size considerations. The implications of these findings for clinical applications of Hp and for its physiological behavior are discussed.

Adsorptive partitioning of an organic compound onto polyelectrolyte-immobilized micelles on porous glass and sand.

Halting the spread of organic contaminants in subsurface aquifers is a critical environmental problem. We describe a novel "permeable reactive barrier" that results when organophile-solubilizing properties are conferred on siliceous materials by treating them with a cationic polymer and oppositely charged mixed surfactant micelles. Controlled pore glass, quartz sand, and sea sand were treated with poly(diallyldimethylammonium chloride) and with mixed micelles of Triton X-100 and sodium dodecyl sulfate, either sequentially or simultaneously, following different treatment procedures. A model organophilic compound, Orange OT, was adsorbed and retained under aqueous agitation on the siliceous treated surfaces but not on untreated surfaces or those treated with micelle only. The aspect of the treatment procedure producing the most significant effect on Orange OT solubilization was the ionic strength. The retention of Orange OT in a layer of polyelectrolyte-micelle-treated sand under flow, within a column of untreated sand, demonstrates the possibility of using similar processes as a permeable reactive barrier to trap organic pollutants.

Determination of the compositional distribution of copolymers by frontal analysis continuous capillary electrophoresis.

Frontal analysis continuous capillary electrophoresis (FACCE) was carried out for a series of random copolymers of an ionic monomer, sodium 2-(acrylamido)-2-methylpropanesulfonate (AMPS), and a nonionic monomer, acrylamide (AAM). The electropherograms appeared in order of anionic content and were generally sigmoidal, in contrast to that of hyaluronic acid (HA), which was abrupt and discontinuous. This difference could be related to the compositional heterogeneity of the copolymers, completely absent in the biopolymer. Through the range of copolymer composition (10-100% AMPS) the relationship between average mobility and nominal AMPS content could be described by a calibration curve, making it possible to deduce the compositional distribution of copolymer samples.

pH-induced coacervation in complexes of bovine serum albumin and cationic polyelectrolytes.

Turbidity and light scattering measurements, along with phase contrast microscopy, were used to follow the processes leading to coacervation when aqueous solutions of bovine serum albumin (BSA) and poly-(dimethyldiallylammonium chloride) (PDADMAC) were brought from pH = 4 to 10. The state of macromolecular assembly of complexes formed between BSA and PDADMAC prior to and during the pH-induced coacervation could be characterized by specific pH values at which recognizable transitions took place. In addition to the two characteristic pH values (pHcrit and pH phi) previously identified through turbidimetry, other transitions were explicitly established. On the basis of the pH-induced evolution of scattering intensity measurements, we concluded that the formation of soluble primary protein-polymer complexes is initiated at pHcrit and proceeds until "pH'crit". A subsequent increase in scattering intensity at "pHpre" may arise from the assembly of quasi-neutralized primary complexes as their net positive charge decreases with increase in pH. Subsequently, a maximum in scattering intensity at pH phi is observed coincident with the appearance of turbidity and also corresponding to the first microscopic observation of coacervate droplets. The temperature independence of pHcrit and pH phi suggests that hydrophobic contributions are negligible for the initial BSA-PDADMAC interactions and the subsequent coacervation process. The pH dependence of scattering intensity profiles allowed the identification of two other transitions beyond pH phi. Spherical microcoacervate droplets first observed around pH phi subsequently displayed morphological changes at "pHmorph", followed by the transformation to solid or flocculant substances at pHprecip.

Light scattering, CD, and ligand binding studies of ferrihemoglobin-polyelectrolyte complexes.

Quasi-elastic light scattering (QELS), electrophoretic light scattering (ELS), CD spectroscopy, and azide binding titrations were used to study the complexation at pH 6.8 between ferrihemoglobin and three polyelectrolytes that varied in charge density and sign. Both QELS and ELS show that the structure of the soluble complex formed between ferrihemoglobin and poly(diallyldimethylammonium chloride) [PDADMAC] varies with protein concentration. At fixed 1.0 mg/mL polyelectrolyte concentration, protein addition increases complex size and decreases complex mobility in a tightly correlated manner. At 1.0 mg/mL of greater protein concentration, a stable complex is formed between one polyelectrolyte chain and many protein molecules (i.e., an intrapolymer complex) with apparent diameter approximately 2.5 times that of the protein-free polyelectrolyte. Under conditions of excess polyelectrolyte, each of the three ferrihemoglobin-polyelectrolyte solutions exhibits a single diffusion mode in QELS, which indicates that all protein molecules are complexed. CD spectra suggest little or no structural disruption of ferrihemoglobin upon complexation. Azide binding to the ferrihemoglobin-poly(2-acrylamide-2-methylpropanesulfonate) [PAMPS] complex is substantially altered relative to the polyelectrolyte-free protein, but minimal change in induced by complexation with an AMPS-based copolymer of reduced linear charge density. The change in azide binding induced by PDADMAC is intermediate between that of PAMPS and its copolymer.

Binding of proteins to copolymers of varying hydrophobicity.

Hydrophobic interactions between proteins and amphiphilic polyelectrolytes were studied by frontal analysis continuous capillary electrophoresis (Gao et al., Analytical Chemistry, 1997, Vol. 69, pp. 2945-2951). Binding isotherms were obtained for beta-lactoglobulin and for bovine serum albumin interacting with a series of alternating copolymers of maleic acid and alkyl-vinyl ethers of varying hydrophobicity. Although binding between proteins and copolymers increases with increasing alkyl chain length, a minimum alkyl chain length of 3-4 methylenes is required for significant hydrophobic interactions to occur. These copolymers, like other polyamphiphiles, can form intrapolymer micelles, and the extent of such micellization decreases with increasing degree of carboxylate ionization. Binding results obtained at different pHs suggest that competition exists between intrapolymer micelle formation and protein-polymer hydrophobic interactions.

Protein binding on polyelectrolyte-treated glass. Effect of structure of adsorbed polyelectrolyte.

Polyelectrolyte adsorption can be used to modify the surface of chromatographic packings in order to make them more suitable for protein separations. We studied the binding of proteins to controlled pore glass (CPG) on which the polycation poly(diallyldimethylammonium chloride) (PDADMAC) was noncovalently immobilized through electrostatic interaction. We found that the selectivity of PDADMAC for bovine serum albumin vs. beta-lactoglobulin, identified in previous selective coacervation studies, is conserved after its immobilization on the CPG surface. Protein binding results showed that the pH, ionic strength, and mixing time for polyelectrolyte adsorption all affect subsequent protein binding, presumably via the molecular properties of the adsorbed polyelectrolyte layer. The polyelectrolyte adsorption layer thickness, for polyelectrolyte adsorbed at pH 9.0, ionic strength I = 0.001, was measured with size-exclusion chromatography as delta H = 2.5 +/- 0.5 nm. Quasielastic light scattering measurement of the polyelectrolyte hydrodynamic layer thickness (HLT) with a model system of PDADMAC and silica, supported a correlation between the structure of the adsorbed polyelectrolyte layer (e.g., loops and tails) and subsequent protein binding, although differences in magnitude between delta H and HLT suggest that adsorption onto silica may not mimic adsorption on CPG.

Measurement of the binding of proteins to polyelectrolytes by frontal analysis continuous capillary electrophoresis.

We have developed a novel technique, frontal analysis continuous capillary electrophoresis (FACCE), to study the binding of proteins to polyelectrolytes. Compared with existing electrophoresis methods such as conventional frontal analysis and the Hummel-Dreyer method, FACCE offers enhanced lower detection limits and is free from effects due to slow binding kinetics, thus making it suitable for studying equilibrium systems. In addition, with a single calibration, FACCE provides for efficient quantitative analysis. Here we report results obtained with ß-lactoglobulin as the ligand and sodium poly(styrenesulfonate) (NaPSS) as the ligand-binding substrate. For this model system, FACCE yields reproducible calibration curves and binding isotherms. The binding parameters so determined are compared with previous results for other protein-polyelectrolyte systems.

Effect of EO Chain Length of Dodecanol Ethoxylates (C12En) on the Complexation of C12En/SDS Mixed Micelles with an Oppositely Charged Polyelectrolyte

Turbidimetry, dynamic light scattering, and capillary electrophoresis were used to study the complexation of polydiallyldimethylammonium chloride (PDADMAC) with mixed micelles of sodium dodecyl sulfate (SDS) and dodecanol ethoxylates (C12En). The effect of EO chain length and its distribution was examined using various combinations of C12En (n = 4, 6, 8, 12). The results show that the onset of the complexation of PDADMAC with the mixed micelles is affected by the EO chain length of C12En: the mole fraction (Y) of SDS in the mixed micelle required to form the complex (Yc) increases with n. The effect of EO chain length on the onset of bulk phase separation shows the same trend. Although Yc varies with n, the electrophoretic mobility of mixed micelles with composition corresponding to Yc is independent of n. We propose that the effect of EO chain length has two aspects: (1) an increase in the average distance between bound polycation segments and the SDS sulfate groups, and (2) an increase in the distance between SDS head groups, which causes a decrease in the surface charge density (sigma) of the micelle. Therefore, the electrical potential at the mean locus of bound polymer segments, psi0, decreases with increasing n; in order for complexation to occur, this effect must be compensated for by a larger value of Y. Broader distributions of EO chain length lead to an increase in the range of Y over which the soluble complex is stable. We suggest that polycations initially bind to micelles which are rich in shorter EO chains and thus have higher "surface" potential, psi0. However, additional SDS may go preferentially into micelles rich in longer chains with lower psi0. This delays the formation of micelles which have sufficiently large psi0 to cause phase separation.

[Acute pancreatitis from obstruction of Wirsung's canal by Taenia saginata (author's transl)]. / Pancréatite aiguë par obstruction taeniasique du canal de Wirsung.

A case is reported of acute edematous pancreatitis due to obstruction of Wirsung's canal by Taenia saginata rings. The patients recovered after release of the obstruction by sphincterotomy followed by drainage of the biliary tract.