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Open Access Review

The role of lipopolysaccharide as a marker of immune activation in HIV-1 infected patients: a systematic literature review

Matteo Vassallo1*, Patrick Mercié2, Jacqueline Cottalorda3, Michel Ticchioni4 and Pierre Dellamonica1

Author Affiliations

1 Department of Infectious Diseases, L’Archet Hospital, University of Nice, Nice, France

2 Department of Internal Medicine, University of Bordeaux, Bordeaux, France

3 Department of Virology, L’Archet Hospital, University of Nice, Nice, France

4 Department of Immunology, L’Archet Hospital, University of Nice, Nice, France

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Virology Journal 2012, 9:174  doi:10.1186/1743-422X-9-174

Published: 27 August 2012

Abstract

Background

Recent observational studies suggest a role for lipopolysaccharide (LPS) as a marker of immune activation in HIV-infected patients, with potential repercussions on the effectiveness of antiretroviral regimens.

Object

A systematic review of LPS as a marker of immune activation in HIV-1 infected patients.

Data sources

MEDLINE register of articles and international conference proceedings.

Review methods

Case–control studies comparing the role of plasma LPS as a marker of immune activation in HIV-infected patients versus HIV negative subjects.

Data synthesis

Two hundred and six articles were selected using MEDLINE, plus 51 studies presented at international conferences. Plasma LPS is a marker of immune activation in HIV-infected patients, determining the entry of central memory CD4+ T cells into the replication cycle and finally generating cell death. Plasma LPS probably results from immune-mediated alterations of the intestinal barrier, which can occur soon after HIV seroconversion. LPS is a likely marker of disease progression, as it drives chronic monocyte activation, and some studies suggest that hyperexpression of CCR5 receptors, related to LPS plasma levels, could be responsible for monocyte trafficking in the brain compartment and for the appearance of HIV-associated neurocognitive disorders. Long-term combination antiretroviral therapy (cART) generally reduces LPS concentrations, but rarely to the same levels as in the control group. This phenomenon probably depends on ongoing but incomplete repair of the mucosal barrier. Only in patients achieving maximal viral suppression (i.e. viral load < 2.5 cp/ml) are LPS levels comparable to healthy donors. In successfully treated patients who did not restore CD4+ T cells, one hypothesis is that the degree of residual microbial translocation, measured by LPS, alters the turnover of CD4+ T cells.

Conclusions

LPS is a marker of microbial translocation, responsible for chronic immune activation in HIV-infected patients. Even in successfully treated patients, LPS values are rarely normal. Several studies suggest a role for LPS as a negative predictive marker of immune restoration in patients with blunted CD4 T cell gain.