Lymphopenia-induced proliferation of CD4 T-cells is associated with CD4 T-lymphocyte exhaustion in treated HIV-infected patients

Pathological proliferation: a potential mechanism for poor CD4+ T cell recovery in people living with HIV

Background

People living with HIV (PLWH) fail to achieve normalization of CD4+ T cell counts and function, especially in immunological non-responders (INRs). The frequencies of Ki67+CD4+ T cells were inversely associated with CD4+ T cell counts in HIV infected patients. Early ART did not normalize CD4+ T cell proliferation. However, the features of the abnormal proliferation CD4+ T cell in INRs are far from known.

Method

PLWH were divided into INRs (n= 16) and immunological responders (IRs, n= 53) groups. Mass cytometry was applied to peripheral blood T cells to profile the immune cells and liquid chip technique was used to measure plasma levels of cytokines and chemokines. Correlation analyses were conducted to evaluate associations between the degree of CD4+ T cell proliferation and immune function.

Results

The percentage of Ki67+ CD4+ T cells were significant higher in INRs, and we defined these cells with significant higher level of Ki67, as over-proliferating cells. No significant difference of markers' expression (HLA-DR, CD38, CD57, PD-1, PD-L1, CD107a, perforin) was found between INRs and IRs. Compared with naïve CD4+ T cells in INRs, Ki67+ CD4+ T cells exhibited lower levels of CD57 and CD38. Whereas Ki67+ T cells exhibited higher levels of CD38 and CD57 and activation compared with differentiated mature central memory CD4+ T cells and effector memory CD4+ T cells. Ki67+ cells did not show higher levels of senescence and activation compared to certain Ki67- CD4+ central memory T cells in IRs. Furthermore, Ki67+ CD4+ Tcm cells exhibited positive correlations with pro-inflammatory cytokines.

Conclusion

We proposed and validated the hypothesis of "pathological proliferation" in INRs: excessive proliferation of CD4+ T cells in INRs may be accompanied by aberrant activation, senescence and loss of immune function. Eventually, such over-proliferating but poor-quality cells in INRs result in incomplete recovery of both CD4+ T cell counts and function. An intervention that enhancing the proliferative capacity or functional ability or both of CD4+ T cell in INRs might therefore be beneficial.

Persistent T cell proliferation and MDSCs expansion precede incomplete CD4+ T cell recovery in people with acute HIV-1 infection with early ART

HIV-1 infection causes T cell dysfunction that cannot be fully restored by anti-retroviral therapy (ART). Myeloid-derived suppressor cells (MDSCs) expand and suppress T cell function during viral infection. In this study, we evaluated the dynamics of phenotypes and function of T cells and MDSCs and the effects of their interaction on CD4⁺ T cell reconstitution in people with acute HIV-1 infection (PWAH) with early ART. Flow cytometry was used to detect the phenotypic dynamics and function of T cells and MDSCs at pre-ART, 4, 24, 48, and 96 weeks of ART. We observed that T cells were hyper-activated and hyper-proliferative in PWAH at pre-ART. Early ART normalized T cell activation but not their proliferation. T cell proliferation, enriched in PD-1⁺ T cells, was persisted and negatively associated with CD4⁺ T-cell counts after ART. Moreover, M-MDSCs frequency was increased and positively correlated with T cell proliferation after 96 weeks of ART. M-MDSCs persisted and inhibited T cell proliferation ex vivo, which could be partially reversed by PD-L1 blockade. Further, we found higher frequencies of proliferative CD4⁺ T cells and M-MDSCs in PWAH with lower CD4⁺ T cell numbers (<500 cells/μL) compared to PWAH with higher CD4⁺ T cell numbers (>600 cells/μL) after 96 weeks of ART. Our findings indicate that persistent T cell proliferation, MDSCs expansion, and their interaction may affect CD4⁺ T-cell recovery in PWAH with early ART.

Comparative Transcriptional Analysis Identified Characteristic Genes and Patterns in HIV-Infected Immunological Non-Responders

Purpose

The incomplete immune reconstitution is a complex phenomenon among human immunodeficiency virus (HIV)-infected patients despite the fact that they have achieved persistent viral suppression under the combined antiretroviral therapy. This study aims to screen and verify the immunological characteristics and underlying mechanisms of immunological non-responders (INRs).

Methods

The RNA-seq and the differentially expressed genes (DEGs) analysis were used to explore potential characteristics among INRs. Gene Ontology (GO) enrichment, ingenuity pathway analysis (IPA) analysis, Gene set enrichment analysis (GSEA) analysis, and the weighted gene co-expression network analysis (WGCNA) were used to explore the potential mechanism. The transcriptional meta-analysis was used to analyze the external efficiency.

Results

The RNA-seq identified 316 DEGs among INRs. The interferon signaling pathway was enriched via GO and IPA analysis among DEGs. The combined GSEA and WGCNA analysis confirmed that the IFN response was more correlated with INR. Furthermore, IFI27 (IFN-α Inducible Protein 27, also known as ISG12) was chosen based on combined DEG analysis, WGCNA analysis, and the transcriptional meta-analysis conducted on other published datasets about INRs. The expression of IFI27 was significantly negatively correlated with the CD4+ T-cell counts of PLWH, and the predictive efficiency of IFI27 level in distinguishing PLWH with poor immune recovery was also with significant power (AUC = 0.848).

Conclusion

The enhanced expression of IFI27 and the IFN response pathway are among the important immunological characteristics of INRs and exhibited promising efficiency as biomarkers for CD4⁺ T-cell recovery.

Effects of Artesunate Tablet on Immune Activation and Reconstitution Among Highly Active Antiretroviral Therapy-Treated Patients with Incomplete Immune Responses

The level of T cell activation is a better predictor of CD4⁺ T cell depletion in highly active antiretroviral therapy (HAART) patients than viral load. Artesunate is an artemisinin derivative that has an immunomodulatory effect. This study investigated whether artesunate tablet reduces T cell activation and improves immune reconstitution among patients with suboptimal immune recovery despite receiving long-term effective HAART. This was a randomized prospective parallel open-label trial consisting of 45 participants whose plasma HIV load was effectively suppressed by HAART for >18 months and who had CD4⁺ T cell counts of <300 cells/μL or an increase of <20% from baseline. The patients were randomized 2:1 into the artesunate group or the control group and received artesunate tablets (orally, 50 mg two times daily) combined with HAART or HAART alone, respectively. T cell subsets, activation markers, clinical symptoms, viral load, and side effects were assessed. By 48 weeks, artesunate tablet did not improve CD4⁺ T cell recovery or reduce the activation of T cell subsets but induced in a smaller decline in the expression of T cell activation markers among HAART patients with incomplete immune responses. However, artesunate tablet did appear to reduce the level of T cell apoptosis. One subject developed moderate anemia. Long-term use of artesunate tablet is unlikely to produce substantial clinical benefits in patients receiving HAART who exhibit an incomplete immune response.

Incomplete immune reconstitution in HIV/AIDS patients on antiretroviral therapy: Challenges of immunological non-responders

The morbidity and mortality of HIV type-1 (HIV-1)-related diseases were dramatically diminished by the grounds of the introduction of potent antiretroviral therapy, which induces persistent suppression of HIV-1 replication and gradual recovery of CD4⁺ T-cell counts. However, ∼10-40% of HIV-1-infected individuals fail to achieve normalization of CD4⁺ T-cell counts despite persistent virological suppression. These patients are referred to as "inadequate immunological responders," "immunodiscordant responders," or "immunological non-responders (INRs)" who show severe immunological dysfunction. Indeed, INRs are at an increased risk of clinical progression to AIDS and non-AIDS events and present higher rates of mortality than HIV-1-infected individuals with adequate immune reconstitution. To date, the underlying mechanism of incomplete immune reconstitution in HIV-1-infected patients has not been fully elucidated. In light of this limitation, it is of substantial practical significance to deeply understand the mechanism of immune reconstitution and design effective individualized treatment strategies. Therefore, in this review, we aim to highlight the mechanism and risk factors of incomplete immune reconstitution and strategies to intervene.

Phenotypical T Cell Differentiation Analysis: A Diagnostic and Predictive Tool in the Study of Primary Immunodeficiencies

Multiparametric flow cytometry (MFC) represents a rapid, highly reproducible, and sensitive diagnostic technology for primary immunodeficiencies (PIDs), which are characterized by a wide range of T cell perturbations and a broad clinical and genetic heterogeneity. MFC data from CD4+ and CD8+ T cell subsets were examined in 100 patients referred for Primary Immunodeficiencies to our center. Naïve, central memory, effector memory, and terminal effector memory cell differentiation stages were defined by the combined expression CD45RA/CD27 for CD4 and CD45RA/CCR7 for CD8. Principal component analysis (PCA), a non-hypothesis driven statistical analysis, was applied to analyze MFC data in order to distinguish the diverse PIDs. Among severe lymphopenic patients, those affected by severe combined and combined immunodeficiency (SCID and CID) segregated in a specific area, reflecting a homogenous, and a more severe T cell impairment, compared to other lymphopenic PID, such as thymectomized and partial DiGeorge syndrome patients. PID patients with predominantly antibody defects were distributed in a heterogeneous pattern, but unexpectedly PCA was able to cluster some patients' resembling CID, hence warning for additional and more extensive diagnostic tests and a diverse clinical management. In conclusion, PCA applied to T cell MFC data might help the physician to estimate the severity of specific PID and to diversify the clinical and diagnostic approach of the patients.