Impact of Raltegravir on Immune Impact of Raltegravir on Immune Reconstitution and Thymopoiesis in Reconstitution and Thymopoiesis in

HIV-1 Infected Patients with HIV-1 Infected Patients with Undetectable ViremiaUndetectable Viremia

Carolina Garrido, N Rallón, N Zahonero, M López, V Soriano, C de Mendoza, and JM Benito

Hospital Carlos III, Madrid

HIV infection and CD4 recoveryHIV infection and CD4 recovery

HIV-infection CD4+T-cellsImmune deficiency

Opportunistic infections

HAART HIV Viral Load CD4+T-cells

Raltegravir First-in-class integrase inhibitor Has proven potent antiviral activity but also showed good immunologic recovery

Background

Raltegravir immunologic outcomes Raltegravir immunologic outcomes Background

THPE0132

700

600

500

400

300

CD

4 co

un

t (c

ell/

mm

3)

ATV DRV RALn

baseline

+ 6 months

Δ CD4

p

CD4+T cells (cell/mm3)

52

524 [344,703]

444 [354,606]

-22 [-127,55]

0.173

25

231 [157-493]

291 [176,492]

28 [-36,80]

0.104

86555 [429-776]630 [472,812]40 [-31,136]

0.012

Switching experiences in HCIII:

- ATV

- DRV

- RAL

Switch one drug for another in a context

of undetectable viremia

Immunologic recovery Immunologic recovery Background

The CD4+T-cell recovery after HAART

can be due to:

Recent thymic emigrants (RTEs)

The expansion of peripheral T cells

Thymus Supply of new lymphocytes to the periphery. Impaired during HIV-infection

Kohler and Thiel, Blood, 2009

Thymic functionThymic function

Thymic function T-cell receptor excision circles (TRECs) Stable DNA episomes

formed during T-cell receptor gene rearrangement within the thymus↑ % cells TREC+ = RTEs

↓ % cells TREC+ = cells after several divisionsTRECs are lost upon cell division

Background

CD31

Surface marker

Present in TREC-rich T-cells

Indicator of recent thymic emigrants

ObjectiveObjective

The aim of the study was

to characterize the immunologic recovery of

HIV-infected patients under suppressed viremia

after switching to a RAL containig regimen

Patients and samplesPatients and samples

Viral load < 50 RNA cop/mL

Baseline +6 months

Switch to a RAL-containig regimenMantain the same regimen

Control group Raltegravir group

For each patient, two blood samples were collected:

one at baseline

one 6 months later

PBMCs were obtained from peripheral blood by density gradient centrifugation

Cells were criopreserved until use

Methods

Immunologic characterizationImmunologic characterization

CD4+T-Lymphocyte

effector naive

effector memory

central memory

- CD4-PC7

- CD45RA-ECD

- CD27-PE

- CD38-PC5

- CD31-FITC

PBMCs were stained with fluorescent-conjugated monoclonal antibodies specific for cell surface markers:

Expression of these surface markers was analyzed by flow cytometry using a 5-color-flow-cytometer FC500 (Coulter, Miami, FL)

Activation marker

Recent thymic emigrants (RTE) marker

Maturation markers

Methods

Study populationStudy population

Baseline characteristics of the study population did not differ among groups

Control group: 84% PI (67% ATV, 17% LPV); 11% NNRTIs; 5% NRTIs

RAL group: 53% PI; 47% 2NRTIs

Results

CD4CD4++T-cell countT-cell count

After the 6-month period, only the group who switched to RAL experienced a significant change in CD4 count

Control

800

600

400

200

0

Raltegravir

CD

4+T

-ce

ll (

ce

ll/m

m3 )

*

Results

CD4CD4++T-cell maturationT-cell maturation

Effector

Naive

Effector memory

Central memory

Effector

Naive

Effector memory

Central memory

0.421

0.014

0.005

0.421

0.117

0.199

0.723

0.133

*

*

Wilcoxon Signed Ranks Testp

After the 6-months period, significant changes in the population subsets distribution only occurred in the RAL group, where the subset of naive cells increased its proportion

+6 monthsBaseline

Co

ntr

ol

Ral

teg

ravi

r

Results

CD31 expressionCD31 expression

CD31 expression did not vary significantly in any of the study groups neither in the whole population or in particular cellular subsets

Results

Baseline

+ 6 months

p=0.811

p=0.306p=0.191

p=0.420

p=0.679p=0.277

p=0.306

p=0.872

p=0.314

p=0.117

CD38 expressionCD38 expression

In the control group there was a slightly significant decrease in the CD38 expression level of both naive and effector subsets

In the RAL group, we observed a significant decrease in the effector population but a significant increase in the level of CD38 expression of naive cells

Results

* ** *

p=0.036

+ 6 months

Baseline

Association between CD38 and CD31Association between CD38 and CD31Results

100806040200

% naïve cells expressing CD31

100

80

60

40

20

0

% n

aïv

e c

ells

exp

ress

ing

CD

38

R Sq Linear = 0,51

Control-RAL + 6 months

Pearson correlation sig (2-tailed) < 0.001

100806040200

100

80

60

40

20

0

R Sq Linear = 0,262

% naïve cells expressing CD31

% n

aïv

e c

ells

exp

ress

ing

CD

38

Control-RAL baseline

Pearson correlation sig (2-tailed) = 0.001

ConclusionsConclusions

Switching to a RAL-containing regimen in a context of suppressed viremia induced a significant gain in CD4+T-cell count.

This improvement was mainly due to an increase in the subset of CD4+Naive cells.

The increase in CD4+naive cells could not be clearly associated to recent thymic emigrants, as there was no significant rise in the expression of CD31.

However, the increase of CD38 expression on naive CD4+T-cells and the significant association between CD38 and CD31 markers on this subset of CD4+ cells, suggest that the immune recovery observed in patients switching to RAL may be due, at least in part, to newly produced cells in the thymus.

AcknowledgmentsAcknowledgmentsInfectious Diseases Department of Hospital Carlos III

(Molecular Biology Lab. + Clinical Section)

Norma Rallón

Mariola López

Jose Miguel Benito

Natalia Zahonero

Carmen de Mendoza

Vicente Soriano