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Updated: Aug 23, 2026
A Mouse Model to Assess Innate Immune Response to Staphylococcus aureus Infection
Published on: February 28, 2019
Three different neutrophil subsets exhibited in mice with different susceptibilities to infection by
Yasuhiro Tsuda1, Hitoshi Takahashi, Makiko Kobayashi
1Division of Infectious Diseases, Department of Internal Medicine, The University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas 77555, USA.
Abstract:
Neutrophils (PMN) have been described as critical effector cells in the host's antibacterial innate immunities. However, the classification of murine PMNs remains unclear. Here, we show that in addition to normal PMN (PMN-N), there are at least two distinct subsets of PMNs (PMN-I and PMN-II) distinguished as follows: (1) cytokine and chemokine production (PMN-I, IL-12/CCL3; PMN-II, IL-10/CCL2; PMN-N, no cytokine/chemokine production), (2) macrophage activation (PMN-I, classically activated macrophages; PMN-II, alternatively activated macrophages; PMN-N, no effect on macrophage activation), (3) Toll-like receptor (TLR) expression (PMN-I, TLR2/TLR4/TLR5/TLR8; PMN-II, TLR2/TLR4/TLR7/TLR9; PMN-N, TLR2/TLR4/TLR9), and (4) surface antigen expression (PMN-I, CD49d(+)CD11b-; PMN-II, CD49d(-)CD11b+; PMN-N, CD49d(-)CD11b-). PMN-I was obtained from MRSA (methicillin-resistant Staphylococcus aureus)-resistant hosts, while MRSA-sensitive hosts were a source of PMN-II. PMN-N was obtained from naive mice. Anti-MRSA innate immunities might be influenced differently by these biochemically and physically distinguished PMNs. PMN-N may convert to PMN-I or PMN-II in response to host circumstance.
Insights
Murine neutrophils (PMN) are classified into three subsets: PMN-N, PMN-I, and PMN-II, each with distinct cytokine production, macrophage activation, and surface antigen expression. These subsets influence antibacterial immunity differently.
Area of Science:
- Immunology
- Cell Biology
Background:
- Neutrophils (PMN) are key in innate antibacterial immunity.
- The classification of murine PMN subsets is not well-defined.
Purpose of the Study:
- To classify distinct subsets of murine neutrophils.
- To characterize differences in cytokine production, macrophage activation, Toll-like receptor (TLR) expression, and surface antigen expression among PMN subsets.
Main Methods:
- Analysis of cytokine and chemokine production.
- Assessment of macrophage activation.
- Evaluation of Toll-like receptor (TLR) and surface antigen expression.
- Isolation of PMN subsets from naive, MRSA-resistant, and MRSA-sensitive mice.
Main Results:
- Three murine PMN subsets identified: PMN-N (normal), PMN-I (IL-12/CCL3, classically activated macrophages, specific TLRs, CD49d+CD11b-), and PMN-II (IL-10/CCL2, alternatively activated macrophages, different TLRs, CD49d-CD11b+).
- PMN-I derived from MRSA-resistant hosts; PMN-II from MRSA-sensitive hosts.
- PMN-N derived from naive mice and can potentially convert to PMN-I or PMN-II.
Conclusions:
- Murine neutrophils comprise at least three distinct subsets with unique functional and phenotypic characteristics.
- These PMN subsets differentially impact anti-MRSA innate immunity.
- Host conditions may induce the conversion of normal PMNs into specific subsets.
