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Posted by AliG (Member # 9734) on :
 
(breaking up for easier reading)

Tick saliva inhibits the chemotactic function of MIP-1α and selectively impairs chemotaxis of immature dendritic cells by down-regulating cell-surface CCR5



Received 17 September 2007; accepted 7 October 2007. Available online 22 October 2007.


Abstract

Ticks are blood-feeding arthropods that secrete immunomodulatory molecules through their saliva to antagonize host inflammatory and immune responses.

As dendritic cells (DCs) play a major role in host immune responses, we studied the effects of Rhipicephalus sanguineus tick saliva on DC migration and function.

Bone marrow-derived immature DCs pre-exposed to tick saliva showed reduced migration towards macrophage inflammatory protein (MIP)-1α, MIP-1β and regulated upon activation, normal T cell expressed and secreted (RANTES) chemokines in a Boyden microchamber assay.

This inhibition was mediated by saliva which significantly reduced the percentage and the average cell-surface expression of CC chemokine receptor CCR5.

In contrast, saliva did not alter migration of DCs towards MIP-3β, not even if the cells were induced for maturation.

Next, we evaluated the effect of tick saliva on the activity of chemokines related to DC migration and showed that tick saliva per se inhibits the chemotactic function of MIP-1α, while it did not affect RANTES, MIP-1β and MIP-3β.

These data suggest that saliva possibly reduces immature DC migration, while mature DC chemotaxis remains unaffected.

In support of this, we have analyzed the percentage of DCs on mice 48 h after intradermal inoculation with saliva and found that the DC turnover in the skin was reduced compared with controls.

Finally, to test the biological activity of the saliva-exposed DCs, we transferred DCs pre-cultured with saliva and loaded with the keyhole limpet haemocyanin (KLH) antigen to mice and measured their capacity to induce specific T cell cytokines.

Data showed that saliva reduced the synthesis of both T helper (Th)1 and Th2 cytokines, suggesting the induction of a non-polarised T cell response.

These findings propose that the inhibition of DCs migratory ability and function may be a relevant mechanism used by ticks to subvert the immune response of the host.


Carlo Jos F. Oliveiraa, Karen A. Cavassania, Daniela D. Mora, Gustavo P. Garletc, Julio C. Alibertid, Joo S. Silvaa and Beatriz R. Ferreiraa, b, ,
aDepartment of Biochemistry and Immunology, School of Medicine of Ribeiro Preto, University of So Paulo (USP), SP, Brazil
bDepartment of Maternal-Child Nursing and Public Health, School of Nursing of Ribeiro Preto, USP, Avenida Bandeirantes 3900, 14040 902 Ribeiro Preto, SP, Brazil
cDepartment of Biological Sciences, School of Dentistry of Bauru, USP, SP, Brazil
dDivision of Molecular Immunology, Cincinnati Children's Hospital Medical Center and University of Cincinnati College of Medicine, Cincinnati, OH, USA


Keywords: Dendritic cells; Saliva; Migration; T cell response; Rhipicephalus sanguineus


Corresponding author. Address: Department of Maternal-Child Nursing and Public Health, School of Nursing of Ribeiro Preto, USP, Avenida Bandeirantes 3900, 14040 902 Ribeiro Preto, SP, Brazil. Tel.: +55 016 3602 3231; fax: +55 016 3602 4590.

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Posted by sparkle7 (Member # 10397) on :
 
This is kind of technical but (I think) it supports a post I made

about transmission of Lyme disease through kissing or sexual

contact. It's the initial bite from the tick where other chemicals in

the tick's saliva prevent the detection of the spirochete in the body.

Human to human contact wouldn't have the same effect as tick to

human... I'm supposing here.
 


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