title: Innate Immune Memory Contributes to Host Defense against Recurrent Skin and Skin Structure Infections Caused by Methicillin-Resistant Staphylococcus aureus.
abstract: Staphylococcus aureus is the leading cause of skin and skin structure infections (SSSI). The high frequency of recurring SSSI due to S. aureus, including methicillin-resistant S. aureus (MRSA) strains, despite high titers of specific antibodies and circulating T cells, implies that traditional adaptive immunity imparts incomplete protection. We hypothesized that innate immune memory contributes to the protective host defense against recurring MRSA infection. To test this hypothesis, SSSI was induced in wild-type and rag1-/-mice in the BALB/c and C57BL/6 backgrounds. Prior infection (priming) of wild-type and rag1-/-mice of either background afforded protection against repeat infection, as evidenced by reduced abscess severities and decreased CFU densities compared to those in naive controls. Interestingly, protection was greater on the previously infected flank than on the naive flank for wild-type and rag1-/-mice. For wild-type mice, protective efficacy corresponded to increased infiltration of neutrophils (polymorphonuclear leukocytes [PMN]), macrophages (MΦ), Langerin+dendritic cells (LDC), and natural killer (NK) cells. Protection was associated with the induction of interleukin-17A (IL-17A), IL-22, and gamma interferon (IFN-γ) as well as the antimicrobial peptides CRAMP and mβD-3. Priming also protected rag1-/-mice against recurring SSSI, with increased MΦ and LDC infiltration and induction of IL-22, CRAMP, and mβD-3. These findings suggest that innate immune memory, mediated by specific cellular and molecular programs, likely contributes to the localized host defense in recurrent MRSA SSSI. These insights support the development of targeted immunotherapeutic strategies to address the challenge of MRSA infection.
authors.affiliation: Division of Molecular Medicine, Harbor-UCLA Medical Center, Torrance, California, USA.|St. John's Cardiovascular Research Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, USA.
authors.forename: Liana C
authors.initials: LC
authors.lastname: Chan
authors.affiliation: Division of Infectious Diseases, Harbor-UCLA Medical Center, Torrance, California, USA.|St. John's Cardiovascular Research Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, USA.
authors.forename: Siyang
authors.initials: S
authors.lastname: Chaili
authors.affiliation: Division of Infectious Diseases, Harbor-UCLA Medical Center, Torrance, California, USA.|St. John's Cardiovascular Research Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, USA.|Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Scott G
authors.initials: SG
authors.lastname: Filler
authors.affiliation: Department of Dermatology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Lloyd S
authors.initials: LS
authors.lastname: Miller
authors.affiliation: Division of Infectious Diseases, Harbor-UCLA Medical Center, Torrance, California, USA.|St. John's Cardiovascular Research Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, USA.
authors.forename: Norma V
authors.initials: NV
authors.lastname: Solis
authors.affiliation: Division of Molecular Medicine, Harbor-UCLA Medical Center, Torrance, California, USA.
authors.forename: Huiyuan
authors.initials: H
authors.lastname: Wang
authors.affiliation: Division of Molecular Medicine, Harbor-UCLA Medical Center, Torrance, California, USA.
authors.forename: Colin W
authors.initials: CW
authors.lastname: Johnson
authors.affiliation: Division of Infectious Diseases, Harbor-UCLA Medical Center, Torrance, California, USA.|St. John's Cardiovascular Research Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, USA.
authors.forename: Hong K
authors.initials: HK
authors.lastname: Lee
authors.affiliation: Division of Infectious Diseases, Harbor-UCLA Medical Center, Torrance, California, USA.|St. John's Cardiovascular Research Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, USA.
authors.forename: Luis F
authors.initials: LF
authors.lastname: Diaz
authors.affiliation: Division of Molecular Medicine, Harbor-UCLA Medical Center, Torrance, California, USA MRYeaman@ucla.edu.|Division of Infectious Diseases, Harbor-UCLA Medical Center, Torrance, California, USA.|St. John's Cardiovascular Research Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, USA.|Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Yeaman
mesh_terms: D000818:Animals; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D004195:Disease Models, Animal; D004198:Disease Susceptibility; D015870:Gene Expression; D054884:Host-Pathogen Interactions / Q000276:immunology*; D007113:Immunity, Innate; D007156:Immunologic Memory; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000276:immunology*; D051379:Mice; D018345:Mice, Knockout; D012008:Recurrence; D013154:Spleen / Q000166:cytology / Q000276:immunology; D013207:Staphylococcal Skin Infections / Q000276:immunology* / Q000382:microbiology* / Q000473:pathology
chemical_list: D016207:Cytokines
keywords: Staphylococcus aureus; immunity; recurrent infection; skin infection