Effective control of recalcitrant pruritus by bevacizumab: a possible role for vascular endothelial growth factor in chronic itch?

Prurigo is a difficult to treat condition characterized by severe pruritus presenting with chronic secondary scratch lesions. We report here a dramatic improvement in pruritus in a patient with prurigo simplex who was being treated with bevacizumab, a monoclonal vascular endothelial growth factor (VEGF) antibody. On the basis of the increased VEGF expression measured in the skin of this patient, serum levels of VEGF were subsequently analysed in 27 consecutive patients with prurigo and 19 healthy controls. VEGF levels were significantly increased in the serum of patients with prurigo. Moreover, VEGF concentrations correlated with physician-assessed disease activity. Based on these observations, we speculate that VEGF is involved in the pathophysiology of prurigo.

German version of ItchyQoL: validation and initial clinical findings.

Pruritus is a major symptom of numerous skin and systemic diseases and causes a substantial burden on patients' quality of life (QoL). We report here the validation of the German version (GerItchyQoL) of the first pruritus-specific QoL instrument ItchyQoL. GerItchyQoL was created from the original version following standard protocols. It was completed by 308 patients with chronic pruritus of different origin and tested for validity, reliability and responsiveness. Factor analysis of Ger-ItchyQoL revealed the 4 domains symptoms, functioning, feelings, and self-perception. Reliability was demonstrated by good internal consistency of all domains. We confirmed convergent validity by comparing the instrument with itch severity, as measured with a visual analogue scale (VAS 0-10), and with the Short-Form-12 (SF-12), a widely used generic health-related QoL instrument. Concurrent validity was shown by the ability to discriminate between patient groups of different itch severity. Changes in GerItchyQoL scores correlated with changes in itch severity (VAS), suggesting responsiveness of the German tool. This study provides preliminary evidence of validity, reliability and responsiveness of GerItchyQoL and also shows a high impact of chronic pruritus on QoL. Further translations of ItchyQoL into additional languages will enable large-scale international, multilingual trials.

Anti-immunoglobulin E treatment of patients with recalcitrant physical urticaria.

In physical urticaria, exogenous physical factors such as thermal triggers, solar radiation and mechanic triggers including friction or pressure are responsible for the elicitation of symptoms in the skin of patients. Avoidance of the respective stimulus is usually difficult or impossible, and many patients are not sufficiently treated with standard antihistamines. We report that treatment with omalizumab (Xolair®) of 7 patients with physical urticarias [solar urticaria (n = 2), urticaria factitia/symptomatic dermographism (n = 2), cold urticaria, delayed pressure urticaria and localized heat urticaria] resulted in complete symptom control within days after the first injection in 5 patients. In 1 patient, symptoms improved after increasing the dose of omalizumab, and 1 patient with localized heat urticaria did not respond significantly to treatment. Before anti-immunoglobulin E treatment, all patients had suffered from their physical urticaria for years and had had numerous unsuccessful therapies. The overall excellent responses to omalizumab treatment reported here indicate that anti-immunoglobulin E is a safe and effective treatment for recalcitrant physical urticarias.

Expression of PHA polymerase genes of Pseudomonas putida in Escherichia coli and its effect on PHA formation.

Poly-3-hydroxyalkanoates (PHAs) are synthesized by many bacteria as intracellular storage material. The final step in PHA biosynthesis is catalyzed by two PHA polymerases (phaC) in Pseudomonas putida. The expression of these two phaC genes (phaC1 and phaC2)was studied in Escherichia coli, either under control of the native promoter or under control of an external promoter. It was found that the two phaC genes are not expressed in E. coli without an external promoter. During heterologous expression of phaC from Plac on a high copy number plasmid, a rapid reduction of the number of colony forming units was observed, especially for phaC2. It appears that the plasmid instability was partially caused by high-level production of PHA polymerase. Subsequently, tightly regulated phaC2 expression systems on a low copy number vector were applied in E. coli. This resulted in PHA yields of over 20 of total cell dry weight, which was 2 fold higher than that obtained from the system where phaC2 is present on a high copy number vector. In addition, the PHA monomer composition differed when different gene expression systems or different phaC genes were applied.

Poly(3-hydroxyalkanoate) polymerase synthesis and in vitro activity in recombinant Escherichia coli and Pseudomonas putida.

We tested the synthesis and in vitro activity of the poly(3-hydroxyalkanoate) (PHA) polymerase 1 from Pseudomonas putida GPo1 in both P. putida GPp104 and Escherichia coli JMU193. The polymerase encoding gene phaC1 was expressed using the inducible PalkB promoter. It was found that the production of polymerase could be modulated over a wide range of protein levels by varying inducer concentrations. The optimal inducer dicyclopropylketone concentrations for PHA production were at 0.03% (v/v) for P. putida and 0.005% (v/v) for E. coli. Under these concentrations the maximal polymerase level synthesized in the E. coli host (6% of total protein) was about three- to fourfold less than that in P. putida (20%), whereas the maximal level of PHA synthesized in the E. coli host (8% of total cell dry weight) was about fourfold less than that in P. putida (30%). In P. putida, the highest specific activity of polymerase was found in the mid-exponential growth phase with a maximum of 40 U/g polymerase, whereas in E. coli, the maximal specific polymerase activity was found in the early stationary growth phase (2 U/g polymerase). Our results suggest that optimal functioning of the PHA polymerase requires factors or a molecular environment that is available in P. putida but not in E. coli.

Production of chiral R-3-hydroxyalkanoic acids and R-3-hydroxyalkanoic acid methylesters via hydrolytic degradation of polyhydroxyalkanoate synthesized by pseudomonads.

A novel and efficient method for the production of enantiomericaly pure R-3-hydroxyalkanoic acids and R-3-hydroxyalkanoic acid methylesters was developed. The described method is based on hydrolysis of poly(hydroxyalkanoate) copolymers synthesized by Pseudomonas putida. The polymer was isolated via solvent recovery and hydrolyzed by acid methanolysis. The obtained 3-hydroxyalkanoic acid methylester mixture was distilled into several fractions with an overall yield of 96.6% (w/w). Gas chromatography-mass spectrometry analysis of the fractions showed that 3-hydroxyhexanoic-, 3-hydroxyoctanoic-, 3 hydroxydecanoic-, and 3-hydroxydodecanoic acid methylesters were enriched to purities exceeding 96 mol%, with distillation yields of 99.9, 99.8, 88.4, and 56.8% (w/w), respectively. Subsequent saponification of the purified methylester fractions yielded the corresponding 3-hydroxyalkanoic acids, which were recovered up to 92.8% (w/w). Chiral gas chromatography analysis confirmed that both 3-hydroxyoctanoic acid and 3-hydroxyoctanoic acid methylester are present in the R-form at a very high enantiomeric excess (>99.9%).