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Published on: April 29, 2015
Effect of histamine on the gene expression and biosynthesis of complement components C2, factor B and C3 in mouse
Abstract:
The gene expression and biosynthesis of C2, factor B and C3 have been investigated in vitro in mouse resident peritoneal macrophages after incubation with histamine. C2- and factor B-specific mRNA and the amount of the immunoprecipitated C2 and factor B were decreased by 10(-4) M and 10(-8) M histamine. These effects can be abrogated by the H2 antagonist cimetidine and mimicked by the H2 agonists impromidine and 4-methylhistamine. Since the H1 antagonist chlorpheniramine and the H1 agonists PEA and 2-methylhistamine have little effect on C2 and are ineffective on factor B, a strong H2 receptor dependence of the inhibition of C2 and factor B gene expression and biosynthesis is suggested. Conversely, the C3 gene expression and biosynthesis can be influenced through both H1 and H2 receptors, e.g. elevated by histamine + cimetidine, PEA and 2-methylhistamine through H1 receptors, and inhibited by histamine + chlorpheniramine, impromidine and 4-methylhistamine through H2 receptors. The data obtained by quantification of C2, factor B and C3 mRNA concentration of peritoneal macrophages suggest that the regulation of biosynthesis of these complement components by histamine in mouse peritoneal macrophages is under pretranslational control.
Insights
Histamine affects complement component production in mouse macrophages. It inhibits C2 and factor B via H2 receptors, while C3 is modulated by both H1 and H2 receptors, indicating pretranslational control.
Area of Science:
- Immunology
- Pharmacology
Background:
- Histamine is a key mediator in immune responses.
- Complement system components like C2, factor B, and C3 are crucial for innate immunity.
- Macrophages play a central role in immune regulation.
Purpose of the Study:
- To investigate the in vitro effects of histamine on the gene expression and biosynthesis of complement components C2, factor B, and C3 in mouse peritoneal macrophages.
- To determine the histamine receptor subtypes (H1 and H2) involved in regulating these complement components.
Main Methods:
- Incubation of mouse resident peritoneal macrophages with varying concentrations of histamine.
- Quantification of C2, factor B, and C3 mRNA levels using specific assays.
- Assessment of protein levels through immunoprecipitation.
- Use of H1 and H2 receptor antagonists and agonists to elucidate receptor involvement.
Main Results:
- Histamine significantly decreased C2 and factor B mRNA and protein levels, an effect mediated primarily through H2 receptors.
- C3 gene expression and biosynthesis were influenced by both H1 and H2 receptors, with differential effects observed.
- The regulation of these complement components by histamine appears to occur at the pretranslational level.
Conclusions:
- Histamine differentially regulates complement component biosynthesis in mouse macrophages.
- C2 and factor B regulation is predominantly H2 receptor-dependent.
- C3 regulation involves both H1 and H2 receptors, suggesting complex histamine signaling pathways in macrophage-mediated immunity.
