CCR5 and CXCR4 chemokine receptor expression and beta-chemokine production during early T cell repopulation induced by highly active anti-retroviral therapy

Abstract

Expression of chemokine receptors and beta-chemokine production by peripheral blood mononuclear cells (PBMC) were determined in HIV-1-infected individuals before and after highly active anti-retroviral therapy (HAART) and their relationship to viral load, T cell phenotype and the expression of immunological activation markers was examined. We found that the expression of CCR5 is up-regulated in HIV-1-infected individuals while CXCR4 appears down-regulated on both CD4 and CD8 T cells compared with normal controls. These alterations are associated with the high levels of viral load. In addition, a relationship was observed between the degree of immune activation and chemokine receptor expression on T cells. However, after 3 months of combined anti-retroviral regimen, expression of CXCR4 significantly increased while CCR5 decreased when compared with pretherapy determinations. This was seen in strict association with a dramatic decrease of viral load and an increase of both CD45RA+/CD62L+ (naive) and CD45RA-/CD62L+ or CD45RA+/CD62L- (memory) T cells accompanied by a significant decrease of the expression of immune activation markers such as HLA-DR and CD38. At enrolment, both spontaneous and lectin-induced RANTES, macrophage inflammatory protein-1alpha (MIP-1alpha) and MIP-1beta production by PBMC were higher in HIV-1-infected individuals compared with normal controls, although differences for MIP-1beta were not statistically significant. However, RANTES and MIP-1alpha production decreased during HAART at levels closer to that determined with normal controls, while MIP-1beta production was less consistently modified. These data indicate that the expression of chemokine receptors CCR5 and CXCR4 and the production of beta-chemokines are altered in HIV-infected individuals, and suggest that their early modifications during HAART reflect both the peripheral redistribution of naive/memory T cell compartments and the decrease in levels of T cell activation. Such modifications in the expression of host determinants of viral tropism and the production of anti-viral molecules may play a role in the emergence of virus variants when a failure of HAART occurs.

Fig. 1

Reciprocal modifications of CCR5 and CXCR4 chemokine receptor expression on CD4⁺ and CD8⁺ T cells during early peripheral repopulation induced by highly active anti-retroviral therapy (HAART). Four-colour flow cytometric analysis was performed with peripheral blood mononuclear cells (PBMC) from HIV-1-infected individuals or normal blood donors at enrolment (time 0) and 3 months after HAART (time 3). The following MoAbs were used: anti-CD4–allophycocyanin (APC), anti-CD8–peridinin chlorophyll protein (PerCP), anti-CCR5–PE clone 2D7 and anti-CXCR4–PE clone 12G5. The expression of CCR5 before therapy was significantly increased in both CD4⁺ (a) and CD8⁺ T cells (b), while the expression of CXCR4 in the same cell types was down-regulated (c and d, respectively) compared with controls (represented by a line on graphs). After 3 months of HAART, the percentage of CCR5-expressing CD4⁺ (a) and CD8⁺ T cells (b) was significantly diminished, while CXCR4 expression was consistently increased (c and d, respectively).

Fig. 2

Modifications of spontaneous and lectin-induced β-chemokine production by peripheral blood mononuclear cells (PBMC) from HIV-1-infected individuals at enrolment (time 0) and 3 months after highly active anti-retroviral therapy (HAART) (time 3). Unstimulated (a) and phytohaemagglutinin (PHA)-induced (b) RANTES, macrophage inflammatory protein-1α (MIP-1α) and MIP-1β production was determined by ELISA in supernatants from PBMC short-term cultures performed with freshly collected blood samples from HIV-1-infected individuals or normal donors (controls). At enrolment, HIV-1-infected individuals produced higher levels of RANTES, MIP-1α and MIP-1β both spontaneously (a) and upon lectin-induction (b), compared with normal controls. However, both spontaneous and induced production of RANTES and MIP-1α consistently decreased after 3 months of HAART, reaching values closer to those detected in control individuals (a,b). MIP-1β lectin-induced production remained at the levels detected at enrolment (a,b).