CD4(+)CD25(High) Treg cells in HIV/HTLV co-infected patients with neuropathy: high expression of Alpha4 integrin and lower expression of Foxp3 transcription factor

Clinical significance of B7-H3 expression in circulating CD4+CD25high T cells, CD14+ monocytes, and plasma for the progression of HIV infection

BACKGROUND

B7-H3 is an important immune checkpoint molecule that plays a negative role in immune regulation. This study was aimed to explore B7-H3 expression in HIV-infected patients and its clinical significance.

METHODS

To explore the expression and clinical significance of B7-H3 in HIV-infected patients, we investigated the B7-H3 expression pattern and the correlation of B7-H3 expression with clinical parameters of HIV-infected patients with different levels of CD4⁺ T cells. To assess the role of B7-H3 in regulating the function of T cells in HIV infection, we performed a proliferation assay and T cell function test in vitro.

RESULTS

B7-H3 expression in HIV-infected patients was significantly higher than that in healthy controls. mB7-H3 expression on CD4⁺CD25^high T cells and CD14⁺ monocytes increased with disease progression. mB7-H3 expression on CD4⁺CD25^high T cells and monocytes was negatively correlated with lymphocyte count, CD4⁺T cell count, and positively correlated with HIV viral load in HIV-infected patients. when the number of CD4⁺ T cells in HIV-infected patients was ≥ 200/µL, sB7-H3 and mB7-H3 expression levels on CD4⁺CD25^high T cells and monocytes were negatively correlated with lymphocyte count, CD4⁺T cell count. sB7-H3 and mB7-H3 expression on monocytes were positively correlated with HIV viral load. B7-H3 inhibited the proliferation of lymphocytes and the secretion of IFN-γ in vitro, especially the ability of CD8⁺ T cells to secrete IFN-γ.

CONCLUSIONS

B7-H3 played an important negative regulatory role in anti-HIV infection immunity. It could be used as a potential biomarker for the progression of HIV infection and a novel target for the treatment of HIV infection.

Reduced frequency and functional potency of CD49d- T regulatory cells in patients with newly diagnosed type 2 diabetes mellitus

This study set out to check the quantitative and qualitative properties of peripheral CD4⁺CD25⁺CD49d^- T regulatory (CD49d^- Treg) cells in type 2 diabetes mellitus (T2DM) patients. This work comprised 35 newly diagnosed patients and 35 healthy controls (HCs). The frequency of FoxP3 expressing CD49d^- Treg cells was determined by flow cytometry. The gene expression of FoxP3 and CD49d was assessed by real-time PCR. Suppression assays with purified CD49d^- Treg cells and CD4⁺CD25^- T conventional (Tconv) cells were done by flow cytometry. The supernatants of Tconv/CD49d^- Treg co-cultures were tested for IFN-γ, IL-4, IL-17, and IL-10 using ELISA. The frequency of CD49d^- Treg cells (by both CD4⁺CD25⁺CD49d^- and CD4⁺CD25⁺⁺CD49d^- phenotypes) observed to be reduced in patients versus HCs. In the patients, decreased protein and gene expression of FoxP3 was seen in CD49d^- Treg cells. Suppressive potency of CD49d^- Treg cells to inhibit Tconv cells proliferation was diminished, and inversely related to fasting plasma glucose and hemoglobin A1c in the patients. Tconv cells from T2DM patients released higher amount of IL-17 and lower concentration of IL-10 versus HCs. In Tconv/CD49d^- Tregs co-cultures, decreased IL-17 and increased IL-10 levels were seen in HCs, but not T2DM patients. CD49d^- Treg cells from the patients have a fundamental defect and Treg cells fail to inhibit the aggressive inflammatory responses.

HTLV infected individuals have increased B-cell activation and proinflammatory regulatory T-cells

Human T-lymphotropic virus (HTLV) affects the human immune system in many ways, most notably by inducing proliferation of infected CD4 + T cells, but several other cell types are also affected. To characterize the effects of HTLV infection, we analysed blood samples from HTLV-infected individuals by flow cytometry. Samples were collected from visitors at the HIV clinic in Bissau, Guinea-Bissau. These samples were tested for HTLV and HIV, and 199 were analysed by flow cytometry using panels for B cells, T-cell maturation and activation, regulatory T cells (Tregs) and monocytes. CD80+ cell proportions were significantly higher in HTLV infected than in HTLV uninfected in all B cell subsets. Among T cells, there was no change in cell distribution between maturation stages, but a higher CD25+ proportion among Tregs (61.1 % vs 36.3 %, p < 0.001) in HTLV infected than in HTLV uninfected. The level of CD49d on individual cells was also higher (MFI 2734.5 vs 1,041, p < 0.001). In HTLV infected individuals, CD8 + T cells had a lower proportion of CTLA-4+ (2.5 % vs 3.5 %, 0.048) and higher PD1+ proportion on the CD45RO + subset (81.6 % vs 77.1 %, p < 0.001). Together, these findings point toward reduced regulation in HTLV + patients, which leads to immune activation. This study corroborates previous findings and offers new insight into the effects of HTLV by providing a broad flowcytometric analysis of immune cells in HTLV + individuals.

Helios + Regulatory T cell frequencies are correlated with control of viral replication and recovery of absolute CD4 T cells counts in early HIV-1 infection

BACKGROUND

The acute phase of HIV infection is characterized by massive depletion of CD4 T cells, high viral plasma levels and pronounced systemic immune activation. Regulatory T cells (Tregs) have the potential to control systemic immune activation but also to suppress antigen specific T and B cell response. The co-expression of FoxP3 and Helios transcription factors, has been described for identification of highly suppressive Tregs. The aim of this study was to characterize the phenotype of classic Tregs during early HIV infection, and to assess the correlations between the frequencies and phenotype of Tregs with the plasma viral load, CD4 counts, immune activation and the frequency of antibodies reactive to HIV-1 proteins, measured by an immunochromatographic test.

RESULTS

The relative frequency of classic Tregs cells in peripheral blood correlated positively with HIV viral load and immune activation of CD8 T cells, and inversely with absolute CD4 counts and development of anti-HIV antibodies in subjects with early HIV infection. However, the expression of Helios in classic Tregs was inversely correlated with viral replication and immune activation, and positively with recovery of CD4 T cell counts and appearance of antibodies reactive to HIV-1 proteins.

CONCLUSION

These results raise the hypothesis that classic Tregs are inefficient at controlling systemic immune activation in subjects with early HIV infection and may be associated with delayed production of antibodies against HIV proteins, delaying the control of viral replication. Conversely, Helios expressing Tregs might contribute to control of viral replication by mechanisms involving the limitation of systemic immune activation.

Regulatory T Cell and Forkhead Box Protein 3 as Modulators of Immune Homeostasis

The transcription factor forkhead box protein 3 (FOXP3) is an essential molecular marker of regulatory T cell (Treg) development in different microenvironments. Tregs are cells specialized in the suppression of inadequate immune responses and the maintenance of homeostatic tolerance. Studies have addressed and elucidated the role played by FOXP3 and Treg in countless autoimmune and infectious diseases as well as in more specific cases, such as cancer. Within this context, the present article reviews aspects of the immunoregulatory profile of FOXP3 and Treg in the management of immune homeostasis, including issues relating to pathology as well as immune tolerance.

Trypanosoma cruzi Experimental Infection Impacts on the Thymic Regulatory T Cell Compartment

The dynamics of regulatory T cells in the course of Trypanosoma cruzi infection is still debated. We previously demonstrated that acute murine T. cruzi infection results in an impaired peripheral CD4+Foxp3+ T cell differentiation due to the acquisition of an abnormal Th1-like phenotype and altered functional features, negatively impacting on the course of infection. Moreover, T. cruzi infection induces an intense thymic atrophy. As known, the thymus is the primary lymphoid organ in which thymic-derived regulatory T cells, known as tTregs, differentiate. Considering the lack of available data about the effect of T. cruzi infection upon tTregs, we examined tTreg dynamics during the course of disease. We confirmed that T. cruzi infection induces a marked loss of tTreg cell number associated to cell precursor exhaustion, partially avoided by glucocorticoid ablation- and IL-2 survival factor depletion. At the same time, tTregs accumulate within the CD4 single-positive compartment, exhibiting an increased Ki-67/Annexin V ratio compared to controls. Moreover, tTregs enhance after the infection the expression of signature markers (CD25, CD62L and GITR) and they also display alterations in the expression of migration-associated molecules (α chains of VLAs and chemokine receptors) such as functional fibronectin-driven migratory disturbance. Taken together, we provide data demonstrating profound alterations in tTreg compartment during acute murine T. cruzi infection, denoting that their homeostasis is significantly affected. The evident loss of tTreg cell number may compromise the composition of tTreg peripheral pool, and such sustained alteration over time may be partially related to the immune dysregulation observed in the chronic phase of the disease.