ABSTRACT
Human peripheral blood monocytes are found as two distinct populations based upon differential expression of chemokine receptors, adhesion molecules, Fc receptors, and cytokines. cDNA microarray analysis now reveals additional differences between these subsets that suggest dramatically diverse functions. One monocyte subset (CD14++CD16-) appears to be closely paired with neutrophils, and may have as its primary function the removal and recycling of apoptotic neutrophils at sites of inflammation. The other monocyte subset (CD14+CD16+) expresses numerous genes encoding proteins with antimicrobial activity and thus may be more directly involved in peripheral host defense. The production of monocytes capable of efficiently removing dying neutrophils may be necessary to prevent host tissue damage and autoimmune response induction. Therefore, species like humans that produce relatively high levels of circulating neutrophils must also produce relatively high numbers of the recycling monocytes. Conversely, species such as mice and rats that maintain relatively lower levels of circulating neutrophils require fewer recycling monocytes.
Subject(s)
Gene Expression Regulation/immunology , Immunity, Innate/genetics , Monocytes/immunology , Animals , Female , Flow Cytometry , Gene Expression Profiling/methods , Humans , L-Selectin/analysis , Leukocyte Count , Lipopolysaccharide Receptors/analysis , Male , Mice , Mice, Inbred C57BL , Monocytes/chemistry , Monocytes/classification , Neutrophils/immunology , Oligonucleotide Array Sequence Analysis , RNA, Messenger/analysis , Rats , Rats, Sprague-Dawley , Receptors, IgG/analysis , Species SpecificityABSTRACT
Primary macrophages from the peritoneal cavities of mice are commonly used ex vivo to produce inflammatory cytokines and test anti-inflammatory agents. Although approximately 1 million peritoneal macrophages can be obtained from an untreated mouse, more than twice that number can be collected 48 to 72 h after intraperitoneal injection of sterile inducing agents such as Brewer thioglycollate broth, casein, and proteose peptone. However, whether 'induced' macrophages are functionally equivalent to 'resident' peritoneal macrophages has been unclear. Flow cytometric analysis revealed significant phenotypic differences between these 2 macrophage types. Resident and induced peritoneal macrophages also demonstrated markedly different capacities to produce the inflammatory cytokines interleukins 6 and 1beta in response to lipopolysaccharide stimulation in vitro. Increased understanding of the differences between resident and induced peritoneal macrophages likely will help investigators decide which macrophage type is appropriate for their in vitro assay needs.
Subject(s)
Macrophages, Peritoneal/classification , Macrophages, Peritoneal/immunology , Animals , Cytokines/biosynthesis , Female , Flow Cytometry , Immunomagnetic Separation , In Vitro Techniques , Inflammation Mediators/metabolism , Lipopolysaccharides/pharmacology , Macrophages, Peritoneal/drug effects , Mice , Mice, Inbred MRL lpr , Mice, Inbred NOD , Mice, Inbred Strains , Phenotype , Tumor Necrosis Factor-alpha/biosynthesis , Zymosan/pharmacologyABSTRACT
The Type 1 PI3Kinases comprise a family of enzymes, which primarily phosphorylate PIP2 to give the second messenger PIP3, a key player in many intracellular signaling processes [Science, 2002, 296, 1655; Trends Pharmacol. Sci.2003, 24, 366]. Of the four type 1 PI3Ks, the gamma-isoform, which is expressed almost exclusively in leukocytes [Curr. Biol., 1997, 7, R470], is of particular interest with respect to its role in inflammatory diseases such as rheumatoid arthritis (RA) and chronic obstructive pulmonary disease (COPD) [Mol. Med. Today, 2000, 6, 347]. Investigation of a series of 4,6-disubstituted-4H-benzo[1,4]oxazin-3-ones has led to the identification of single-digit nanomolar inhibitors of PI3Kgamma, several of which had good cell based activity and were shown to be active in vivo in an aspectic peritonitis model of inflammatory cell migration.