Relative chemokine and adhesion molecule expression in Mediterranean spotted fever and African tick bite fever.
OBJECTIVE
Mediterranean spotted fever (MSF) caused by Rickettsia conorii (R. conorii) is a potential lethal disease while African tick bite fever (ATBF) caused by Rickettsia africae is a self-limiting flu-like illness. We hypothesized that different inflammatory potential in endothelial cells could contribute to the different clinical features in these rickettsioses.


METHODS
We analyzed the effect of heat-inactivated R. africae and R. conorii on the mRNA and protein levels of monocyte chemoattractant protein (MCP)-1, interleukin (IL)-8 and adhesion molecules in endothelial cells. Serum samples from patients with MSF (n=16) and ATBF (n=15) were collected before and after therapy.


RESULTS
R. conorii induced a marked increase in MCP-1, IL-8, and adhesion molecules in endothelial cells, involving toll-like receptor 4 activation. In contrast, R. africae induced MCP-1 expression, but only modest or no responses were seen on IL-8 and adhesion molecules. Comparable to the in vitro response, levels of IL-8 and adhesion molecules showed no or only a modest increase in ATBF patients while these inflammatory markers were markedly elevated during MSF.


CONCLUSIONS
Our findings suggest a superior inflammatory potential of R. conorii as compared to R. africae in endothelial cells, potentially related to the more severe inflammation in MSF comparing ATBF.
Damås
Jan K
JK
Research Institute for Internal Medicine, Rikshospitalet University Hospital, 0027 Oslo, Norway. jan.k.damas@ntnu.no
Davì
Giovanni
G
Jensenius
Mogens
M
Santilli
Francesca
F
Otterdal
Kari
K
Ueland
Thor
T
Flo
Trude H
TH
Lien
Egil
E
Espevik
Terje
T
Frøland
Stig S
SS
Vitale
Giustina
G
Raoult
Didier
D
Aukrust
Pål
P
D000328:Adult; D000818:Animals; D001907:Boutonneuse Fever / Q000276:immunology*; D015815:Cell Adhesion Molecules / Q000096:biosynthesis*; D002478:Cells, Cultured; D018925:Chemokines / Q000096:biosynthesis*; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D007299:Insect Bites and Stings / Q000150:complications*; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000382:microbiology; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000096:biosynthesis; D012282:Rickettsia Infections / Q000276:immunology*; D016996:Rickettsieae / Q000276:immunology; D013987:Ticks
D015815:Cell Adhesion Molecules; D018925:Chemokines; D012333:RNA, Messenger