Immune profiles of pre-frail people living with HIV-1: a prospective longitudinal study

Abstract

Background: People living with HIV (PLWH) are at risk of frailty, which is predictive for death. As an overactivity of the immune system is thought to fuel frailty, we characterized the immune activation profiles linked to frailty.

Methods: We quantified twenty-seven activation markers in forty-six virological responders (four females and forty-two males; median age, 74 years; median duration of infection, 24 years; median duration of undetectability, 13 years), whose frailty was determined according to the Fried criteria. T cell and NK cell activation was evaluated by flow cytometry, using a panel of cell surface markers. Soluble markers of inflammation, and monocyte activation and endothelial activation were measured by ELISA. The participants' immune activation was profiled by an unsupervised double hierarchical clustering analysis. We used ANOVA p-values to rank immunomarkers most related to Fried score. A Linear Discriminant Analysis (LDA) was performed to link immune activation markers to frailty.

Results: 41% of the participants were pre-frail, including 24% with a Fried score of 1, and 17% with a Fried score of 2. ANOVA identified the 14 markers of T cell, monocyte, NK cell, endothelial activation, and inflammation the most linked to Fried 3 classes. The LDA performed with these 14 markers was capable of discriminating volunteers according to their Fried score. Two out of the 5 immune activation profiles revealed by the hierarchical clustering were linked to and predictive of pre-frailty. These two profiles were characterized by a low percentage of CD4 T cells and a high percentage of CD8 T cells, activated CD4 T cells, CD8 T cells, and NK cells, and inflammation.

Conclusions: We identified a particular immune activation profile associated with pre-frailty in PLWH. Profiling participants at risk of developing frailty might help to tailor the screening and prevention of medical complications fueled by loss of robustness. Further studies will indicate whether this frailty signature is specific or not of HIV infection, and whether it also precedes frailty in the general population.

Fig. 1

Frequencies of CD4 T cells (A) and CD8 T cells (B) cells in participants with Fried score of 0, 1, and 2. ANOVA was used to compare differences. Immune activation marker map resulting from the bidimensional representation of the samples into the new subspace generated by the first two LDA axes (C). LDA axis 1 globally separates robust samples from frailty ones, whereas LDA axis 2 allows splitting of the two levels of frailty, demonstrating a clear association between immune activation markers and Fried scores (0, yellow circle; 1, red circle, 2, purple circle, (D). Correlation of each feature to the two LDA axes shows markers mostly associated to the discrimination of the groups

Fig. 2

Heatmap showing the hierarchical clustering of activation markers (vertical) and participants (horizontal) according to their activation profile. Each profile number is indicated

Fig. 3

Characterization of the five immune activation profiles. Difference in the frequency of activated NK cells between Profile 1 participants and the other participants (A). Difference in tPA plasma level between Profile 2 participants and the other participants (B). Difference in the frequency of naïve CD4 T cells between Profile 3 participants and the other participants (C). Difference in the frequency of CD57-expressing CD4 T cells between Profile 4 participants and the other participants (D). Difference in sCD163 plasma level between Profile 5 participants and the other participants (E). Differences were evaluated using an unpaired t test or a Mann-Whitney test, as appropriate

Fig. 4

Proportion of robust and pre-frail participants in Profiles 2 and 5 (closed histogram) and the other Profiles (shaded histogram). The difference was evaluated using a Chi-square test (A). VACS score (B), age (C), EPICES score (D), and comorbidity frequency (E) in HIV participants with different immune activation profiles. Differences were evaluated using an unpaired t test or a Mann-Whitney test, as appropriate

Fig. 5

Characterization of the immune activation Profiles 2 and 5. Differences in the frequency of CD4 T cells (A), CD8 T cells (B), CD38-positive CD4 T cells (C), CD38-positive CD8 T cells (D), activated NK cells (E), and in sTNFRI plasma level (F) between Profiles 2 and 5 and the other profiles. Differences were evaluated using an unpaired t test or a Mann-Whitney test, as appropriate

Fig. 6

Proportion of participants robust at Month 0 becoming pre-frail or not over one year according to their initial immune activation profiles (Profiles 2 and 5, closed histogram, Profiles 1, 3, and 4, shaded histogram). The difference was evaluated using a Chi-square test