Cytokine Detection and Modulation in Acute Graft vs. Host Disease in Mice

A murine model for acute lethal graft vs. host disease (GVHD) was used to study the role that a number of cytokines play in the development of lethal GVHD. In this study we focused on the role of IL-1, IL-2, IL-4, IL-6, IFN-γ and TNF-α. Lethally irradiated (C57BL × CBA)F1 mice were reconstituted either with 107 allogeneic BALB/c spleen cells or with a similar number of syngeneic cells, as a control. A significant rise in serum levels of IL-6, TNF-α and IFN-γ levels was found in allogeneically reconstituted mice. This is in contrast to the syngeneic control group in which no rise was seen. Serum IL-2 and IL-4 levels were below the detection limit. In the supernatant of Con A stimulated spleen cells from allogeneically reconstituted mice IL-6, IFN-γ and TNF-α concentrations were increased. The expression of mRNA for cytokines as detected by reverse transcription PCR was studied in spleen cells. In the allogeneic reconstituted mice the mRNA expression of IL-1α, IL-2, IL-6, IFN-γ and TNF-α displayed faster kinetics compared with that in syngeneic reconstituted mice. The effect of treatment with recombinant cytokines, antibodies to cytokines and to cytokine receptors on the development of GVHD was investigated. Administration of recombinant IL-2 to allogeneically reconstituted mice strongly increased the morbidity and mortality whereas injection of IL-1α and TNF-α did not influence survival. Administration of antibodies against IL-2 or the IL-2 receptor decreased the morbidity and mortality. Anti-IL-6, anti-IFN-γ, and anti-TNF-α mAB, on the other hand, did not affect the morbidity and mortality of GVHD. The results of this study suggest successive waves of cytokine-secreting cell populations consistent with the induction of an inflammatory response in the development of acute GVH disease

Hydrophobically Modified Sulfobetaine Copolymers with Tunable Aqueous UCST through Postpolymerization Modification of Poly(pentafluorophenyl acrylate)

Polysulfobetaines, polymers carrying highly polar zwitterionic side chains, present a promising research field by virtue of their antifouling properties, hemocompatibility, and stimulus-responsive behavior. However, limited synthetic approaches exist to produce sulfobetaine copolymers comprising hydrophobic components. Postpolymerization modification of an activated ester precursor, poly(pentafluorophenyl acrylate), employing a zwitterionic amine, 3-((3-aminopropyl)dimethylammonio)propane-1-sulfonate, ADPS, is presented as a novel, one-step synthetic concept toward sulfobetaine (co)polymers. Modifications were performed in homogeneous solution using propylene carbonate as solvent with mixtures of ADPS and pentylamine, benzylamine, and dodecylamine producing a series of well-defined statistical acrylamido sulfobetaine copolymers containing hydrophobic pentyl, benzyl, or dodecylacrylamide comonomers with well-controllable molar composition as evidenced by NMR and FT-IR spectroscopy and size exclusion chromatography.This synthetic strategy was exploited to investigate, for the first time, the influence of hydrophobic modification on the upper critical solution temperature (UCST) of sulfobetaine copolymers in aqueous solution. Surprisingly, incorporation of pentyl groups was found to increase solubility over a wide composition range, whereas benzyl groups decreased solubility—an effect attributed to different entropic and enthalpic contributions of both functional groups. While UCST transitions of polysulfobetaines are typically limited to higher molar mass samples, incorporation of 0–65 mol % of benzyl groups into copolymers with molar masses of 25.5–34.5 kg/mol enabled sharp, reversible transitions from 6 to 82 °C in solutions containing up to 76 mM NaCl, as observed by optical transmittance and dynamic light scattering. Both synthesis and systematic UCST increase of sulfobetaine copolymers presented here are expected to expand the scope and applicability of these smart materials

Photophysical and Electrochemical Investigations of the Fluorescent Probe, 4,4′-Bis(2-benzoxazolyl)stilbene

In solution, 4,4′-bis­(2-benzoxazolyl)­stilbene (BBS) was found to exhibit consistently high absolute fluorescence quantum yields (Φ_fl ≥ 0.88) and a monoexponential lifetime, both independent of BBS concentration. The BBS steady-state and time-resolved photophysics were investigated by different techniques to understand the various deactivation pathways. Nonradiative deactivation of BBS singlet excited state by intersystem crossing was found to be negligible. Other than fluorescence, the excited state of BBS was found to be deactivated by <i>trans</i>–<i><i>cis</i></i> photoisomerization. At low concentrations (≈5 μg/mL), UV spectroscopy and laser flash photolysis showed concordant results that the photoinduced <i><i>cis</i></i> isomer gradually replaced the original absorption spectrum of the pure <i>trans</i> isomer. However, at high concentrations (≈0.2 mg/mL), ¹H NMR and DOSY measurements confirmed that irradiating BBS at 350 nm induced a conversion from the <i>trans</i>-BBS into its <i>cis</i> isomer by photoisomerization. It was further found that the stilbene moiety of both isomers was photocleaved. The resulting photoproduct was an aldehyde that was oxidized under ambient conditions to its corresponding carboxylic acid, i.e., 4-(1,3-benzoxazol-2-yl)­benzoic acid. The structure of the photoproduct was unequivocally confirmed by X-ray diffraction. Spectroscopic investigation of BBS showed a limited photoisomerization after irradiation at 350 nm of a <i>trans</i> solution. The BBS electrochemistry showed irreversible oxidation, resulting in an unstable and highly reactive radical cation. Similarly, the cathodic process was also found to be irreversible, giving rise to a radical anion and showing its n-doping character

Photophysical and Electrochemical Investigations of the Fluorescent Probe, 4,4′-Bis(2-benzoxazolyl)stilbene

In solution, 4,4′-bis­(2-benzoxazolyl)­stilbene (BBS) was found to exhibit consistently high absolute fluorescence quantum yields (Φ_fl ≥ 0.88) and a monoexponential lifetime, both independent of BBS concentration. The BBS steady-state and time-resolved photophysics were investigated by different techniques to understand the various deactivation pathways. Nonradiative deactivation of BBS singlet excited state by intersystem crossing was found to be negligible. Other than fluorescence, the excited state of BBS was found to be deactivated by <i>trans</i>–<i><i>cis</i></i> photoisomerization. At low concentrations (≈5 μg/mL), UV spectroscopy and laser flash photolysis showed concordant results that the photoinduced <i><i>cis</i></i> isomer gradually replaced the original absorption spectrum of the pure <i>trans</i> isomer. However, at high concentrations (≈0.2 mg/mL), ¹H NMR and DOSY measurements confirmed that irradiating BBS at 350 nm induced a conversion from the <i>trans</i>-BBS into its <i>cis</i> isomer by photoisomerization. It was further found that the stilbene moiety of both isomers was photocleaved. The resulting photoproduct was an aldehyde that was oxidized under ambient conditions to its corresponding carboxylic acid, i.e., 4-(1,3-benzoxazol-2-yl)­benzoic acid. The structure of the photoproduct was unequivocally confirmed by X-ray diffraction. Spectroscopic investigation of BBS showed a limited photoisomerization after irradiation at 350 nm of a <i>trans</i> solution. The BBS electrochemistry showed irreversible oxidation, resulting in an unstable and highly reactive radical cation. Similarly, the cathodic process was also found to be irreversible, giving rise to a radical anion and showing its n-doping character