The histamine H(1)-receptor antagonist cetirizine does not interact with bradykinin B(1) or B(2)-receptors in vitro

Skin microdialysis: methods, applications and future opportunities-an EAACI position paper

Skin microdialysis (SMD) is a versatile sampling technique that can be used to recover soluble endogenous and exogenous molecules from the extracellular compartment of human skin. Due to its minimally invasive character, SMD can be applied in both clinical and preclinical settings. Despite being available since the 1990s, the technique has still not reached its full potential use as a tool to explore pathophysiological mechanisms of allergic and inflammatory reactions in the skin. Therefore, an EAACI Task Force on SMD was formed to disseminate knowledge about the technique and its many applications. This position paper from the task force provides an overview of the current use of SMD in the investigation of the pathogenesis of chronic inflammatory skin diseases, such as atopic dermatitis, chronic urticaria, psoriasis, and in studies of cutaneous events during type 1 hypersensitivity reactions. Furthermore, this paper covers drug hypersensitivity, UVB-induced- and neurogenic inflammation, and drug penetration investigated by SMD. The aim of this paper is to encourage the use of SMD and to make the technique easily accessible by providing an overview of methodology and applications, supported by standardized operating procedures for SMD in vivo and ex vivo.

Rupatadine effectively prevents the histamine-induced up regulation of histamine H1R and bradykinin B2R receptor gene expression in the rat paw

BACKGROUND

Activation of histamine H1 receptor (H1R) is a well-known hallmark of allergic and inflammatory pathology. Both types of bradykinin receptors (B1R and B2R) are also known to contribute significantly to the latter and some sort of functional interaction between them and H1R has been alluded to in the past. Here we use an experimental model of rat paw oedema formation to examine the effect of exogenously added histamine on the gene expression of H1R and bradykinin receptors B1R and B2R, alone or in combination to rupatadine, a second generation antihistamine agent.

METHODS

Histamine-induced oedema formation was monitored with a plethysmometer. The gene expression of H1R, B1R and B2R was analyzed with both conventional and real-time PCR. Rupatadine fumarate was used in pure form and administered intraperitoneally, prior to histamine injection into the paw. Microscopy of haematoxylin and eosin-stained sections of paw tissue was used to examine effects on tissue architecture.

RESULTS

Histamine injection into the paw resulted in significant up regulation of H1R and B2R without inducing significant cellular infiltration, but appears to affect less the expression of B1R. Rupatadine was, under the conditions used in this study, very effective in preventing this effect and in suppressing oedema formation through its antihistamine action.

CONCLUSION

Rupatadine has a suppressing effect on H1R and B2R gene expression which could add to its efficacy towards allergy and allergy-like conditions.

Platelet-activating factor (PAF) induces wheal and flare skin reactions independent of mast cell degranulation

BACKGROUND

Platelet-activating factor (PAF) causes wheal and flare responses which are abrogated by H1-antihistamines giving rise to the hypothesis that PAF-induced wheal development is secondary to histamine release from dermal mast cells. But is this hypothesis correct?

METHODS

Wheal and flare responses were induced by intradermal injection of PAF, codeine and histamine in 14 healthy volunteers. Dermal histamine and PGD2 contractions were measured using microdialysis.

RESULTS

PAF, unlike histamine and codeine, did not cause a statistically significant rise in mean histamine levels with ten persons showing negligible histamine release. Codeine caused a significant but variable histamine release, ranging from 29 to 282 ng/ml. Codeine, but not PAF or histamine, caused a small but statistically significant release of PGD2.

CONCLUSION

Wheal and flare reactions in human skin induced by PAF are not associated with histamine release and, therefore, appear to be independent of mast cell degranulation.