Details

Autor(en) / Beteiligte

• Ismail, Nahed
• Stevenson, Heather L
• Walker, David H

Titel

Role of Tumor Necrosis Factor Alpha (TNF-[alpha]) and Interleukin-10 in the Pathogenesis of Severe Murine Monocytotropic Ehrlichiosis: Increased Resistance of TNF Receptor p55- and p75-Deficient Mice to Fatal Ehrlichial Infection

Ist Teil von

• Infection and Immunity, 2006-03, Vol.74 (3), p.1846-1856

Ort / Verlag

Washington, DC: American Society for Microbiology

Erscheinungsjahr

2006

Quelle

MEDLINE

Beschreibungen/Notizen

• Intraperitoneal (i.p.) infection with a high dose of a highly virulent Ehrlichia strain (IOE) results in a toxic shock-like syndrome characterized by severe liver injury and systemic overproduction of tumor necrosis factor alpha (TNF-[alpha]) by CD8⁺ T cells. We examined the role of TNF-[alpha] and TNF receptors in high-dose-IOE-induced shock/liver injury. TNF receptor (TNFR) I/II[superscript -/-] mice lacking both the p55 and p75 receptors for this cytokine were more resistant to IOE-induced liver injury than their wild-type background controls. TNFR I/II[superscript -/-] mice survived longer, dying between 15 and 18 days, with evidence of mild liver necrosis/apoptosis. In contrast, wild-type mice were not rescued from the lethal effect of IOE by TNF-[alpha] neutralization. TNF-[alpha]-depleted mice developed severe liver injury and succumbed to disease between days 9 and 11 postinfection, similar to sham-treated, infected wild-type mice. Although IFN-[gamma] production in the spleens of IOE-infected TNFR I/II[superscript -/-] and TNF-[alpha]-depleted mice was higher than that detected in wild-type controls, these mice had higher bacterial burdens than infected controls. Following high-dose IOE challenge, TNFR I/II[superscript -/-] and TNF-[alpha]-depleted mice have an early increase in IL-10 levels in sera and spleens, which was produced mainly by adherent spleen cells. In contrast, a late burst of interleukin-10 (IL-10) was observed in control mice. Nonadherent spleen cells were the major source of IL-10 in IOE-infected wild-type mice. We conclude that TNFR I/II and TNF-[alpha] participate in Ehrlichia-induced shock and host defense by regulating liver injury and controlling ehrlichial burden. Our data suggest that fatal ehrlichiosis could be a multistep process, where TNF-[alpha] is not solely responsible for mortality.