Phagocytosis by macrophages depends on histamine H2 receptor signaling and scavenger receptor 1

We demonstrate that histamine 2 receptor is required for phagocytosis of bacteria and microspheres by mouse macrophages. Expression of key autophagy pathway genes is increased, and Macrophage Scavenger Receptor 1 is decreased in abundance in histamine 2 receptor ‐deficient macrophages. AbstractThe histamine H2 receptor (H2R) is a G protein ‐coupled receptor that mediates cyclic AMP production, protein kinase A activation, and MAP kinase signaling. In order to explore the multifaceted effects of histamine signaling on immune cells, phagocytosis was evaluated using primary mouse‐derived macrophages. Phagocytosis is initiated by sign aling via surface‐bound scavenger receptors and can be regulated by autophagy. Absence of H2R signaling resulted in diminished phagocytosis of live bacteria and synthetic microspheres by primary macrophages from histamine H2 receptor gene (Hrh2) ‐deficient mice. Flow cytometry and immunofluorescence microscopy were used to quantify phagocytosis of phylogenetically diverse bacteria as well as microspheres of defined chemical composition. Autophagy and scavenger receptor gene expression were quantified in macrophages after exposure toEscherichia coli. Expression of the autophagy genes,Becn1 andAtg12, was increased inHrh2−/− macrophages, indicating upregulation of autophagy pathways. Expression of the Macrophage Scavenger Receptor 1 gene (Msr1) was diminished inHrh2‐deficient macrophages, supporting the possible importance of histamine ...
Source: MicrobiologyOpen - Category: Microbiology Authors: Tags: ORIGINAL ARTICLE Source Type: research