Higher CD27+CD8+ T Cells Percentages during Suppressive Antiretroviral Therapy Predict Greater Subsequent CD4+ T Cell Recovery in Treated HIV Infection

HIV-mediated immune dysfunction may influence CD4⁺ T cell recovery during suppressive antiretroviral therapy (ART). We analyzed cellular biomarkers of immunological inflammation, maturation, and senescence in HIV-infected subjects on early suppressive ART. We performed longitudinal analyses of peripheral immunological biomarkers of subjects on suppressive ART (n = 24) from early treatment (median 6.4 months, interquartile range [IQR] 4.8–13.9 months) to 1–2 years of follow-up (median 19.8 months, IQR 18.3–24.6 months). We performed multivariate regression to determine which biomarkers were associated with and/or predictive of CD4⁺ T cell recovery. After adjusting for the pre-ART CD4⁺ T cell count, age, proximal CD4⁺ T cell count, and length of ART medication, the percentage of CD27⁺CD8⁺ T cells remained significantly associated with the CD4⁺ T cell recovery rate (β = 0.092 cells/ul/month, P = 0.028). In HIV-infected subjects starting suppressive ART, patients with the highest percentage of CD8⁺ T cells expressing CD27 had the greatest rate of CD4⁺ T cell recovery.     

Initiation of Antiretroviral Therapy (ART) at Different Stages of HIV-1 Disease Is Not Associated with the Proportion of Exhausted CD8+ T Cells

CD8⁺ T cell-restricted immunity is important in the control of HIV-1 infection, but continued immune activation results in CD8⁺ T cell dysfunction. Early initiation of antiretroviral treatment (ART) and the duration of ART have been associated with immune reconstitution. Here, we evaluated whether restoration of CD8⁺ T cell function in HIV-1-infected individuals was dependent on early initiation of ART. HIV-specific CD107a, IFNγ, IL-2, TNFα and MIP-1β expression by CD8⁺ T cells and the frequency of CD8⁺ T cells expressing PD-1, 2B4 and CD160 were measured by flow cytometry. The frequency of CD8⁺ T cells expressing the inhibitory markers PD-1, 2B4 and CD160 was lower in ART-treated individuals compared with ART-naïve individuals and similar to the frequency in HIV-uninfected controls. The expression of the three markers was similarly independent of when therapy was initiated. Individuals treated before seroconversion displayed an HIV-specific CD8⁺ T cell response that included all five functional markers; this was not observed in individuals treated after seroconversion or in ART-naïve individuals. In summary, ART appears to restore the total CD8⁺ T cell population to a less exhausted phenotype, independent of the time point of initiation. However, to preserve multifunctional, HIV-1-specific CD8⁺ T cells, ART might have to be initiated before seroconversion.     

High Current CD4+ T Cell Count Predicts Suboptimal Adherence to Antiretroviral Therapy

High levels of adherence to antiretroviral therapy (ART) are necessary for achieving and maintaining optimal virological suppression, as suboptimal adherence leads to therapy failure and disease progression. It is well known that adherence to ART predicts therapy response, but it is unclear whether clinical outcomes of ART predict adherence. To examine the predictive power of current CD4⁺ T cell count for adherence of HIV-infected individuals to ART, we performed a cross-sectional analysis of 133 Dutch HIV patients with electronically measured adherence. In a multivariate analysis adjusting for a number of sociodemographic and clinical variables, high current CD4⁺ T cell count (>660 cells/mm³) was most strongly associated with lower adherence to ART (assessed as a continuous variable) during a two-month period immediately following the measurements of variables (P = 0.008). The twice-per-day (versus once-per-day) dosing regimen was also significantly associated with lower adherence (P = 0.014). In a second multivariate analysis aimed at determining the predictors of suboptimal (<100% of the doses taken) adherence, high current CD4⁺ T cell count was again the strongest independent predictor of suboptimal adherence to ART (P = 0.015), and the twice-per-day dosing regimen remained associated with suboptimal adherence (P = 0.025). The association between suboptimal adherence and virological suppression was significant in patients with high CD4⁺ T cell counts, but not in patients with low or intermediate CD4⁺ T cell counts (P = 0.036 and P = 0.52, respectively; P = 0.047 for comparison of the effects of adherence on virological suppression between patients with high vs. low or intermediate CD4⁺ T cell counts), suggesting that apart from promoting suboptimal adherence, high CD4⁺ T cell count also strengthens the effect of adherence on virological suppression. Therefore, sustained efforts to emphasize continued adherence are necessary, especially for patients with high CD4⁺ T cell counts.     

The role of CD101-expressing CD4 T cells in HIV/SIV pathogenesis and persistence

Despite the advent of effective antiretroviral therapy (ART), human immunodeficiency virus (HIV) continues to pose major challenges, with extensive pathogenesis during acute and chronic infection prior to ART initiation and continued persistence in a reservoir of infected CD4 T cells during long-term ART. CD101 has recently been characterized to play an important role in CD4 Treg potency. Using the simian immunodeficiency virus (SIV) model of HIV infection in rhesus macaques, we characterized the role and kinetics of CD101⁺ CD4 T cells in longitudinal SIV infection. Phenotypic analyses and single-cell RNAseq profiling revealed that CD101 marked CD4 Tregs with high immunosuppressive potential, distinct from CD101^- Tregs, and these cells also were ideal target cells for HIV/SIV infection, with higher expression of CCR5 and α4β7 in the gut mucosa. Notably, during acute SIV infection, CD101⁺ CD4 T cells were preferentially depleted across all CD4 subsets when compared with their CD101^- counterpart, with a pronounced reduction within the Treg compartment, as well as significant depletion in mucosal tissue. Depletion of CD101⁺ CD4 was associated with increased viral burden in plasma and gut and elevated levels of inflammatory cytokines. While restored during long-term ART, the reconstituted CD101⁺ CD4 T cells display a phenotypic profile with high expression of inhibitory receptors (including PD-1 and CTLA-4), immunsuppressive cytokine production, and high levels of Ki-67, consistent with potential for homeostatic proliferation. Both the depletion of CD101⁺ cells and phenotypic profile of these cells found in the SIV model were confirmed in people with HIV on ART. Overall, these data suggest an important role for CD101-expressing CD4 T cells at all stages of HIV/SIV infection and a potential rationale for targeting CD101 to limit HIV pathogenesis and persistence, particularly at mucosal sites.     

CXCR6+CD4+ T cells promote mortality during Trypanosoma brucei infection

Liver macrophages internalize circulating bloodborne parasites. It remains poorly understood how this process affects the fate of the macrophages and T cell responses in the liver. Here, we report that infection by Trypanosoma brucei induced depletion of macrophages in the liver, leading to the repopulation of CXCL16-secreting intrahepatic macrophages, associated with substantial accumulation of CXCR6⁺CD4⁺ T cells in the liver. Interestingly, disruption of CXCR6 signaling did not affect control of the parasitemia, but significantly enhanced the survival of infected mice, associated with reduced inflammation and liver injury. Infected CXCR6 deficient mice displayed a reduced accumulation of CD4⁺ T cells in the liver; adoptive transfer experiments suggested that the reduction of CD4⁺ T cells in the liver was attributed to a cell intrinsic property of CXCR6 deficient CD4⁺ T cells. Importantly, infected CXCR6 deficient mice receiving wild-type CD4⁺ T cells survived significantly shorter than those receiving CXCR6 deficient CD4⁺ T cells, demonstrating that CXCR6⁺CD4⁺ T cells promote the mortality. We conclude that infection of T. brucei leads to depletion and repopulation of liver macrophages, associated with a substantial influx of CXCR6⁺CD4⁺ T cells that mediates mortality.     

研究报告: 实验性自身免疫性葡萄膜炎模型中肝脏免疫系统紊乱的研究

葡萄膜炎是一种反复发作的炎症性疾病,可导致免疫系统功能障碍和多器官损伤．然而,葡萄膜炎是否导致肝功能损害尚不十分清楚．本文通过运用流式分析技术和激光共聚焦成像技术,研究了实验性自身免疫葡萄膜炎模型的肝脏病理和功能变化．结果显示肝损伤可出现在葡萄膜炎的炎症后期并与眼损伤程度相关．并且CD3⁺ CD4⁺ T细胞、CD3^- NK1.1⁺ DX5^- NK细胞、和CD11b⁺ F4/80^- ly6c⁺ 细胞在感染的眼睛和肝脏中增加．将CD3⁺ CD4⁺ T细胞回输给炎症的小鼠后,眼睛和肝脏的病理损伤加重．此外,在炎症的小鼠中可见血管扩张,大量淋巴细胞浸润到炎症的眼和肝脏的血管周围．总之,我们的研究结果提示,肝损伤可以发生在小鼠葡萄膜炎模型中,这种损伤可能与通过外周循环浸润到肝脏的CD3⁺ CD4⁺ T细胞有关．     

Chemokine Transfer by Liver Sinusoidal Endothelial Cells Contributes to the Recruitment of CD4+ T Cells into the Murine Liver

Leukocyte adhesion and transmigration are central features governing immune surveillance and inflammatory reactions in body tissues. Within the liver sinusoids, chemokines initiate the first crucial step of T-cell migration into the hepatic tissue. We studied molecular mechanisms involved in endothelial chemokine supply during hepatic immune surveillance and liver inflammation and their impact on the recruitment of CD4⁺ T cells into the liver. In the murine model of Concanavalin A-induced T cell-mediated hepatitis, we showed that hepatic expression of the inflammatory CXC chemokine ligands (CXCL)9 and CXCL10 strongly increased whereas homeostatic CXCL12 significantly decreased. Consistently, CD4⁺ T cells expressing the CXC chemokine receptor (CXCR)3 accumulated within the inflamed liver tissue. In histology, CXCL9 was associated with liver sinusoidal endothelial cells (LSEC) which represent the first contact site for T-cell immigration into the liver. LSEC actively transferred basolaterally internalized CXCL12, CXCL9 and CXCL10 via clathrin-coated vesicles to CD4⁺ T cells leading to enhanced transmigration of CXCR4⁺ total CD4⁺ T cells and CXCR3⁺ effector/memory CD4⁺ T cells, respectively in vitro. LSEC-expressed CXCR4 mediated CXCL12 transport and blockage of endothelial CXCR4 inhibited CXCL12-dependent CD4⁺ T-cell transmigration. In contrast, CXCR3 was not involved in the endothelial transport of its ligands CXCL9 and CXCL10. The clathrin-specific inhibitor chlorpromazine blocked endothelial chemokine internalization and CD4⁺ T-cell transmigration in vitro as well as migration of CD4⁺ T cells into the inflamed liver in vivo. Moreover, hepatic accumulation of CXCR3⁺ CD4⁺ T cells during T cell-mediated hepatitis was strongly reduced after administration of chlorpromazine. These data demonstrate that LSEC actively provide perivascularly expressed homeostatic and inflammatory chemokines by CXCR4- and clathrin-dependent intracellular transport mechanisms thereby contributing to the hepatic recruitment of CD4⁺ T-cell populations during immune surveillance and liver inflammation.     

Adipose Tissue Is a Neglected Viral Reservoir and an Inflammatory Site during Chronic HIV and SIV Infection

Two of the crucial aspects of human immunodeficiency virus (HIV) infection are (i) viral persistence in reservoirs (precluding viral eradication) and (ii) chronic inflammation (directly associated with all-cause morbidities in antiretroviral therapy (ART)-controlled HIV-infected patients). The objective of the present study was to assess the potential involvement of adipose tissue in these two aspects. Adipose tissue is composed of adipocytes and the stromal vascular fraction (SVF); the latter comprises immune cells such as CD4⁺ T cells and macrophages (both of which are important target cells for HIV). The inflammatory potential of adipose tissue has been extensively described in the context of obesity. During HIV infection, the inflammatory profile of adipose tissue has been revealed by the occurrence of lipodystrophies (primarily related to ART). Data on the impact of HIV on the SVF (especially in individuals not receiving ART) are scarce. We first analyzed the impact of simian immunodeficiency virus (SIV) infection on abdominal subcutaneous and visceral adipose tissues in SIVmac251 infected macaques and found that both adipocytes and adipose tissue immune cells were affected. The adipocyte density was elevated, and adipose tissue immune cells presented enhanced immune activation and/or inflammatory profiles. We detected cell-associated SIV DNA and RNA in the SVF and in sorted CD4⁺ T cells and macrophages from adipose tissue. We demonstrated that SVF cells (including CD4⁺ T cells) are infected in ART-controlled HIV-infected patients. Importantly, the production of HIV RNA was detected by in situ hybridization, and after the in vitro reactivation of sorted CD4⁺ T cells from adipose tissue. We thus identified adipose tissue as a crucial cofactor in both viral persistence and chronic immune activation/inflammation during HIV infection. These observations open up new therapeutic strategies for limiting the size of the viral reservoir and decreasing low-grade chronic inflammation via the modulation of adipose tissue-related pathways.     

CD4+ T cell-mediated cytotoxicity is associated with MHC class II expression on malignant CD19+ B cells in diffuse large B cell lymphoma

Diffuse large B cell lymphoma (DLBCL) is a common B cell malignancy with approximately 30% of patients present relapsed or refractory disease after first-line therapy. Research of further treatment options is needed. Cytotoxic CD4⁺ T cells express cytolytic molecules and have potential antitumor function. Here, we showed that the CD19⁺ cells from DLBCL patients presented significantly reduced expression of MHC II molecules than those from healthy controls. Three years after the first-line treatment, patients that presented relapsed disease had significantly lower MHC II expression on their CD19⁺ cells than patients who did not show recurrence. Examining cytotoxic CD4⁺ T cells show that DLBCL patients presented significantly elevated frequencies of granzyme A-, granzyme B-, and/or perforin-expressing cytotoxic CD4⁺ T cells. Also, frequency of cytotoxic CD4⁺ T cells in DLBCL patients was positively correlated with the MHC II expression level. Subsequently, the cytotoxic potential of CD4⁺ T cells against autologous CD19⁺ cells was investigated. We found that the cytotoxic potential of CD4⁺ T cells was highest in MHC II-high, intermediate in MHC II-mid, and lowest in MHC II-low patients. The percentage of MHC II-expressing viable CD19⁺ cells presented a significant reduction after longer incubation with cytotoxic CD4⁺ T cells, suggesting that cytotoxic CD4⁺ T cells preferentially eliminated MHC II-expressing CD19⁺ cells. Blocking MHC II on CD19⁺ cells significantly reduced the cytolytic capacity of CD4⁺ T cells. Despite these discoveries, the frequency of cytotoxic CD4⁺ T cells did not predict the clinical outcome of DLBCL patients. Together, these results demonstrated that cytotoxic CD4⁺ T cells presented an MHC II-dependent cytotoxic potential against autologous CD19⁺ cells and could potentially represent a future treatment option for DLBCL.     

Latent HIV-1 infection of resting CD4⁺ T cells in the humanized Rag2⁻/⁻ γc⁻/⁻ mouse

Persistent human immunodeficiency virus type 1 (HIV-1) infection of resting CD4⁺ T cells, unaffected by antiretroviral therapy (ART), provides a long-lived reservoir of HIV infection. Therapies that target this viral reservoir are needed to eradicate HIV-1 infection. A small-animal model that recapitulates HIV-1 latency in resting CD4⁺ T cells may accelerate drug discovery and allow the rational design of nonhuman primate (NHP) or human studies. We report that in humanized Rag2^−/− γ_c^−/− (hu-Rag2^−/− γ_c^−/−) mice, as in humans, resting CD4⁺ T cell infection (RCI) can be quantitated in pooled samples of circulating cells and tissue reservoirs (e.g., lymph node, spleen, bone marrow) following HIV-1 infection with the CCR5-tropic JR-CSF strain and suppression of viremia by ART. Replication-competent virus was recovered from pooled resting CD4⁺ T cells in 7 of 16 mice, with a median frequency of 8 (range, 2 to 12) infected cells per million T cells, demonstrating that HIV-1 infection can persist despite ART in the resting CD4⁺ T cell reservoir of hu-Rag2^−/− γ_c^−/− mice. This model will allow rapid preliminary assessments of novel eradication approaches and combinatorial strategies that may be challenging to perform in the NHP model or in humans, as well as a rigorous analysis of the effect of these interventions in specific anatomical compartments.     

Intrahepatic Infiltrating NK and CD8 T Cells Cause Liver Cell Death in Different Phases of Dengue Virus Infection

Elevated liver enzyme level is an outstanding feature in patients with dengue. However, the pathogenic mechanism of liver injury has not been clearly demonstrated. In this study, employing a mouse model we aimed to investigate the immunopathogenic mechanism of dengue liver injury. Immunocompetent C57BL/6 mice were infected intravenously with dengue virus strain 16681. Infected mice had transient viremia, detectable viral capsid gene and cleaved caspase 3 in the liver. In the mean time, NK cell and T cell infiltrations peaked at days 1 and 5, respectively. Neutralizing CXCL10 or depletion of Asialo GM1⁺ cells reduced cleaved caspase 3 and TUNEL⁺ cells in the liver at day 1 after infection. CD8⁺ T cells infiltrated into the liver at later time point and at which time intrahepatic leukocytes (IHL) exhibited cytotoxicity against DENV-infected targets. Cleaved caspase 3 and TUNEL⁺ cells were diminished in mice with TCRβ deficiency and in those depleted of CD8⁺ T cells, respectively, at day 5 after infection. Moreover, intrahepatic CD8⁺ T cells were like their splenic counterparts recognized DENV NS4B_99–107 peptide. Together, these results show that infiltrating NK and CD8⁺ T cells cause liver cell death. While NK cells were responsible for cell death at early time point of infection, CD8⁺ T cells were for later. CD8⁺ T cells that recognize NS4B_99–107 constitute at least one of the major intrahepatic cytotoxic CD8⁺ T cell populations.     

肝癌小鼠外周血及脾脏T淋巴细胞亚群的变化及其意义

目的:观察小鼠原位肝癌模型外周血以及脾脏T淋巴细胞亚群与正常小鼠之间的差异变化,探讨其差异变化的意义。方法:在正常KM小鼠肝脏种植H22细胞,建立小鼠原位模型。采用流式细胞术,以健康正常小鼠为对照,检测肝癌小鼠外周血以及脾脏T淋巴细胞亚群的变化。结果:与健康正常小鼠相比,肝癌小鼠外周血CD4~+T淋巴细胞、CD4~+/CD8~+比例有显著性降低,CD8~+T淋巴细胞显著性升高;脾脏CD3~+、CD4~+T淋巴细胞有显著性降低。结论:小鼠原位肝癌模型外周血以及脾脏T淋巴细胞亚群发生异常,免疫系统紊乱,可以反映小鼠肝癌的发生、发展。     

Elevated ATP via enhanced miRNA-30b, 30c,and 30e downregulates the expression of CD73 in CD8+ T cells of HIV-infected individuals

CD8⁺ T cells play a crucial role against chronic viral infections, however, their effector functions are influenced by the expression of co-stimulatory/inhibitory receptors. For example, CD73 works with CD39 to convert highly inflammatory ATP to adenosine. However, its expression on T cells in the context of viral infections has not been well defined. Here, we analyzed the expression of CD73 on human T cells in a cohort of 102 HIV-infected individuals including those on antiretroviral therapy (ART), ART-naïve, and long-term non-progressors who were not on ART. We found that the frequency of CD73⁺ T cells was markedly lower among T cell subsets (e.g. naïve, effector or memory) in the peripheral blood of all HIV-infected individuals. Notably, CD73 was decreased at the cell surface, intracellular and gene levels. Functionally, CD8⁺CD73⁺ T cells exhibited decreased cytokine expression (TNF-α, IFN-γ and IL-2) upon global or antigen-specific stimulation and impaired expression of cytolytic molecules at the gene and protein levels. In contrast, CD8⁺CD73⁺ T cells expressed elevated levels of homing receptors such as CCR7, α4β7 integrin, which suggests a migratory advantage for these cells as observed in vitro. We also observed significant migration of CD73⁺CD8⁺ T cells into the cerebrospinal fluids of multiple sclerosis (MS) patients at the time of disease relapse. Moreover, we found that elevated levels of ATP in the plasma of HIV-infected individuals upregulates the expression of miRNA30b-e in T cells in vitro. In turn, inhibition of miRNAs (30b, 30c and 30e) resulted in significant upregulation of CD73 mRNA in CD8⁺ T cells. Therefore, we provide a novel mechanism for the downregulation of CD73 via ATP-induced upregulation of miRNA30b, 30c and 30e in HIV infection. Finally, these observations imply that ATP-mediated downregulation of CD73 mainly occurs via its receptor, P2X1/P2RX1. Our results may in part explain why HIV-infected individuals have reduced risk of developing MS considering the role of CD73 for efficient T cell entry into the central nervous system.     

Substantial increase in the frequency of circulating CD4+NKG2D+ T cells in patients with cervical intraepithelial neoplasia grade 1

Background

The NKG2D receptor confers important activating signals to NK cells via ligands expressed during cellular stress and viral infection. This receptor has generated great interest because not only is it expressed on NK cells, but it is also seen in virtually all CD8⁺ cytotoxic T cells and is classically considered absent in CD4⁺ T cells. However, recent studies have identified a distinctive population of CD4⁺ T cells that do express NKG2D, which could represent a particular cytotoxic effector population involved in viral infections and chronic diseases. On the other hand, increased incidence of human papillomavirus-associated lesions in CD4⁺ T cell-immunocompromised individuals suggests that CD4⁺ T cells play a key role in controlling the viral infection. Therefore, this study was focused on identifying the frequency of NKG2D-expressing CD4⁺ T cells in patients with cervical intraepithelial neoplasia (CIN) 1. Additionally, factors influencing CD4⁺NKG2D⁺ T cell expansion were also measured.

Results

Close to 50% of patients with CIN 1 contained at least one of the 37 HPV types detected by our genotyping system. A tendency for increased CD4⁺ T cells and CD8⁺ T cells and decreased NK cells was found in CIN 1 patients. The percentage of circulating CD4⁺ T cells co-expressing the NKG2D receptor significantly increased in women with CIN 1 versus control group. Interestingly, the increase of CD4⁺NKG2D⁺ T cells was seen in patients with CIN 1, despite the overall levels of CD4⁺ T cells did not significantly increase. We also found a significant increase of soluble MICB in CIN 1 patients; however, no correlation with the presence of CD4⁺NKG2D⁺ T cells was seen. While TGF-beta was significantly decreased in the group of CIN 1 patients, both TNF-alpha and IL-15 showed a tendency to increase in this group.

Conclusions

Taken together, our results suggest that the significant increase within the CD4⁺NKG2D⁺ T cell population in CIN 1 patients might be the result of a chronic exposure to viral and/or pro-inflammatory factors, and concomitantly might also influence the clearance of CIN 1-type lesion.     

Attrition of TCR Vα7.2+ CD161++ MAIT Cells in HIV-Tuberculosis Co-Infection Is Associated with Elevated Levels of PD-1 Expression

Mucosal-associated invariant T (MAIT) cells are evolutionarily conserved antimicrobial MR1-restricted CD8⁺ T cells co-expressing the semi-invariant TCR Vα7.2, and are numerous in the blood and mucosal tissues of humans. MAIT cells appear to undergo exhaustion in chronic viral infections. However, their role in human immunodeficiency virus type 1 (HIV-1) mono-infection and HIV/tuberculosis (TB) co-infection have seldom been elaborately investigated. We conducted a cross-sectional study to investigate the frequencies and phenotypes of CD161⁺⁺CD8⁺ T cells among anti-retroviral therapy (ART)/anti-TB therapy (ATT) treatment-naïve HIV/TB co-infected, ART/TB treated HIV/TB co-infected, ART naïve HIV-infected, ART-treated HIV-infected patients, and HIV negative healthy controls (HCs) by flow cytometry. Our data revealed that the frequency of MAIT cells was severely depleted in HIV mono- and HIV/TB co-infections. Further, PD-1 expression on MAIT cells was significantly increased in HIV mono- and HIV-TB co-infected patients. The frequency of MAIT cells did not show any significant increase despite the initiation of ART and/or ATT. Majority of the MAIT cells in HCs showed a significant increase in CCR6 expression as compared to HIV/TB co-infections. No marked difference was seen with expressions of chemokine co-receptor CCR5 and CD103 among the study groups. Decrease of CCR6 expression appears to explain why HIV-infected patients display weakened mucosal immune responses.     

In vitro inhibition of monkeypox virus production and spread by Interferon-β

Background

Despite inducing a sustained increase in CD4+ T cell counts, intermittent recombinant IL-2 (rIL-2) therapy did not confer a better clinical outcome in HIV-infected patients enrolled in large phase III clinical trials ESPRIT and SILCAAT. Several hypotheses were evoked to explain these discrepancies. Here, we investigated the impact of low and high doses of IL-2 in Rhesus macaques of Chinese origin infected with SIVmac251 in the absence of antiretroviral therapy (ART).

Results

We demonstrated that rIL-2 induced a dose dependent expansion of CD4+ and CD8+ T cells without affecting viral load. rIL-2 increased CD4 and CD8 Treg cells as defined by the expression of CD25^highFoxP3⁺CD127^low. We also showed that rIL-2 modulated spontaneous and Fas-mediated CD4⁺ and CD8⁺ T cell apoptosis. The higher dose exhibited a dramatic pro-apoptotic effect on both CD4⁺ and CD8⁺ T cell populations. Finally, all the animals treated with rIL-2 developed a wasting syndrome in the month following treatment simultaneously to a dramatic decrease of circulating effector T cells.

Conclusion

These data contribute to the understanding of the homeostatic and dosage effects of IL-2 in the context of SIV/HIV infection.     

WSX-1 Signalling Inhibits CD4+ T Cell Migration to the Liver during Malaria Infection by Repressing Chemokine-Independent Pathways

IL-27 is an important and non-redundant regulator of effector T cell accumulation in non-lymphoid tissues during infection. Using malaria as a model systemic pro-inflammatory infection, we demonstrate that the aberrant accumulation of CD4⁺ T cells in the liver of infected IL27R^−/− (WSX-1^−/−) mice is a result of differences in cellular recruitment, rather than changes in T cell proliferation or cell death. We show that IL-27 both inhibits the migratory capacity of infection-derived CD4⁺ T cells towards infection-derived liver cells, but also suppresses the production of soluble liver-derived mediator(s) that direct CD4⁺ T cell movement towards the inflamed tissue. Although CCL4 and CCL5 expression was higher in livers of infected WSX-1^−/− mice than infected WT mice, and hepatic CD4⁺ T cells from WSX-1^−/− mice expressed higher levels of CCR5 than cells from WT mice, migration of CD4⁺ T cells to the liver of WSX-1^−/− mice during infection was not controlled by chemokine (R) signalling. However, anti-IL-12p40 treatment reduced migration of CD4⁺ T cells towards infection-derived liver cells, primarily by abrogating the hepatotropic migratory capacity of T cells, rather than diminishing soluble tissue-derived migratory signals. These results indicate that IL-27R signalling restricts CD4⁺ T cell accumulation within the liver during infection primarily by suppressing T cell chemotaxis, which may be linked to its capacity to repress Th1 differentiation, as well as by inhibiting the production of soluble, tissue-derived chemotaxins.     

CD25<Superscript>bright</Superscript>CD4<Superscript>+</Superscript>regulatory T cells are enriched in inflamed joints of patients with chronic rheumatic disease

CD25⁺CD4⁺ regulatory T cells participate in the regulation of immune responses. We recently demonstrated the presence of CD25^brightCD4⁺ regulatory T cells with a capacity to control T cell proliferation in the joints of patients with rheumatoid arthritis. Here, we investigate a possible accumulation of these regulatory T cells in the inflamed joint of different rheumatic diseases including rheumatoid arthritis. The studies are also extended to analyze whether cytokine production can be suppressed by the regulatory T cells. Synovial fluid and peripheral blood samples were obtained during relapse from 36 patients with spondyloarthropathies, 21 adults with juvenile idiopathic arthritis and 135 patients with rheumatoid arthritis, and the frequency of CD25^brightCD4⁺ T cells was determined. Of 192 patients, 182 demonstrated a higher frequency of CD25^brightCD4⁺ T cells in synovial fluid than in peripheral blood. In comparison with healthy subjects, the patients had significantly fewer CD25^brightCD4⁺ T cells in peripheral blood. For functional studies, synovial fluid cells from eight patients were sorted by flow cytometry, and the suppressive capacity of the CD25^brightCD4⁺ T cells was determined in in vitro cocultures. The CD25^brightCD4⁺ T cells suppressed the production of both type 1 and 2 cytokines including interleukin-17, as well as proliferation, independently of diagnosis. Thus, irrespective of the inflammatory joint disease investigated, CD25^brightCD4⁺ T cells were reduced in peripheral blood and enriched in the joint, suggesting an active recruitment of regulatory T cells to the affected joint. Their capacity to suppress both proliferation and cytokine secretion might contribute to a dampening of local inflammatory processes.     

The expansion of CD4<Superscript>+</Superscript>CD28<Superscript>-</Superscript> T cells in patients with rheumatoid arthritis

Clonal expansion of CD4⁺CD28^- T cells is a characteristic finding in patients with rheumatoid arthritis (RA). Expanded CD4⁺ clonotypes are present in the peripheral blood, infiltrate into the joints, and persist for years. CD4⁺CD28^- T cells are oligoclonal lymphocytes that are rare in healthy individuals but are found in high percentages in patients with chronic inflammatory diseases. The size of the peripheral blood CD4⁺CD28^- T-cell compartment was determined in 42 patients with RA and 24 healthy subjects by two-color FACS analysis. The frequency of CD4⁺CD28^- T cells was significantly higher in RA patients than in healthy subjects. Additionally, the number of these cells was significantly higher in patients with extra-articular manifestations and advanced joint destruction than in patients with limited joint manifestations. The results suggest that the frequency of CD4⁺CD28^- T cells may be a marker correlating with extra-articular manifestations and joint involvement.     

CD4+CD25-Foxp3+ T cells: a marker for lupus nephritis?

Introduction

Systemic lupus erythematosus (SLE) is a heterogenous autoimmune disease, which can affect different organs. Increased proportions of CD4⁺CD25^-Foxp3⁺ T cells have been described in SLE patients. The exact role of this cell population in SLE patients still remains unclear. We therefore analyzed this T cell subset in a large cohort of SLE patients with different organ manifestations.

Methods

Phenotypic analyses, proportions and absolute cell numbers of CD4⁺CD25^-Foxp3⁺ T cells were determined by flow cytometry (FACS) in healthy controls (HC) (n = 36) and SLE patients (n = 61) with different organ manifestations. CD4⁺CD25^-Foxp3⁺ T cells were correlated with clinical data, the immunosuppressive therapy and different disease activity indices. In patients with active glomerulonephritis, CD4⁺CD25^-Foxp3⁺ T cells were analyzed in urine sediment samples. Time course analyses of CD4⁺CD25^-Foxp3⁺ T cells were performed in patients with active disease activity before and after treatment with cyclophosphamide and prednisone.

Results

CD4⁺CD25^-Foxp3⁺ T cells were significantly increased in active SLE patients and the majority expressed Helios. Detailed analysis of this patient cohort revealed increased proportions of CD4⁺CD25^-Foxp3⁺ T cells in SLE patients with renal involvement. CD4⁺CD25^-Foxp3⁺ T cells were also detected in urine sediment samples of patients with active glomerulonephritis and correlated with the extent of proteinuria.

Conclusion

CD4⁺CD25^-Foxp3⁺ T cells resemble regulatory rather than activated T cells. Comparative analysis of CD4⁺CD25^-Foxp3⁺ T cells in SLE patients revealed a significant association of this newly described cell population with active nephritis. Therefore CD4⁺CD25^-Foxp3⁺ T cells might serve as an important tool to recognize and monitor SLE patients with renal involvement.