Differential responses of macrophages to Salmonella enterica serovars Enteritidis and Typhimurium.
Macrophages are major effectors against Salmonella infection, and also transport bacteria between host tissues and provide a protected site for intracellular bacterial replication. We hypothesized that differences in chicken macrophage responses to Salmonella enterica serovar Enteritidis (SE) and serovar Typhimurium (ST) played a role in preferential infection of eggs by SE compared with ST. To test this hypothesis, we determined bacterial phagocytosis and intracellular viability and macrophage nitric oxide (NO) production following in vitro infection with SE or ST in the presence or absence of interferon-gamma (IFN-gamma). The effects of bacterial components, lipopolysaccharide (LPS), outer membrane proteins (OMP) and flagella, on NO production were also assessed. Our results showed: (1) in the presence or absence of IFN-gamma, the percentage macrophages phagocytizing SE and ST was similar; (2) the number of intracellular viable SE was significantly reduced compared with ST in the presence or absence of IFN-gamma; (3) increased macrophage necrosis was seen in the presence of IFN-gamma and ST; (4) Salmonella infection acted synergistically with IFN-gamma in induction of nitric oxide production; and (5) in the absence of IFN-gamma, macrophages produced significantly greater NO following treatment with SE outer membrane protein or flagella compared with ST OMP or flagella, while in the presence of IFN-gamma significantly less NO was produced following treatment with SE-LPS compared with ST-LPS. These results suggest that differential responses of chicken macrophages to SE versus ST may result in increased macrophage death with ST, which could result in an increased inflammatory response as compared to SE.
Okamura
Masashi
M
Animal Parasitic Diseases Laboratory, Animal and Natural Resources Institute, Agricultural Research Service, US Department of Agriculture, Bldg 1040 BARC-East Beltsville, MD 20705, USA.
Lillehoj
Hyun S
HS
Raybourne
Richard B
RB
Babu
Uma S
US
Heckert
Robert A
RA
Tani
Hiroyuki
H
Sasai
Kazumi
K
Baba
Eiichiroh
E
Lillehoj
Erik P
EP
D000818:Animals; D017209:Apoptosis; D002645:Chickens; D004531:Eggs / Q000382:microbiology; D005516:Food Microbiology; D066298:In Vitro Techniques; D007371:Interferon-gamma / Q000494:pharmacology; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000276:immunology* / Q000382:microbiology*; D009569:Nitric Oxide / Q000096:biosynthesis; D010587:Phagocytosis; D011994:Recombinant Proteins; D012477:Salmonella enteritidis / Q000276:immunology* / Q000472:pathogenicity; D012486:Salmonella typhimurium / Q000276:immunology* / Q000472:pathogenicity
D011994:Recombinant Proteins; D009569:Nitric Oxide; D007371:Interferon-gamma