Blood T-cell Activation Research Articles

Mechanistic and pharmacodynamic studies of DuoBody-CD3x5T4 in preclinical tumor models.

CD3 bispecific antibodies (bsAbs) show great promise as anticancer therapeutics. Here, we show in-depth mechanistic studies of a CD3 bsAb in solid cancer, using DuoBody-CD3x5T4. Cross-linking T cells with tumor cells expressing the oncofetal antigen 5T4 was required to induce cytotoxicity. Naive and memory CD4+ and CD8+ T cells were equally effective at mediating cytotoxicity, and DuoBody-CD3x5T4 induced partial differentiation of naive T-cell subsets into memory-like cells. Tumor cell kill was associated with T-cell activation, proliferation, and production of cytokines, granzyme B, and perforin. Genetic knockout of FAS or IFNGR1 in 5T4+ tumor cells abrogated tumor cell kill. In the presence of 5T4+ tumor cells, bystander kill of 5T4- but not of 5T4-IFNGR1- tumor cells was observed. In humanized xenograft models, DuoBody-CD3x5T4 antitumor activity was associated with intratumoral and peripheral blood T-cell activation. Lastly, in dissociated patient-derived tumor samples, DuoBody-CD3x5T4 activated tumor-infiltrating lymphocytes and induced tumor-cell cytotoxicity, even when most tumor-infiltrating lymphocytes expressed PD-1. These data provide an in-depth view on the mechanism of action of a CD3 bsAb in preclinical models of solid cancer.

High percentages of peripheral blood T-cell activation in childhood Hodgkin's lymphoma are associated with inferior outcome.

The aims of this study were to investigate the activation of T lymphocytes in peripheral blood from children with Hodgkin's lymphoma (HL) and explore their roles for prognosis in HL. A cohort of 52 newly diagnosed children with HL during the past 10 years was enrolled for analysis in this study. Peripheral blood samples of the patients were acquired before treatment in our hospital, and T-cell subsets were detected by a four-color flow cytometer. CD4+ T cells and CD4+/CD8+ T-cell ratio decreased significantly in patients with HL vs. healthy controls. CD8+ T cells, CD3+CD4+HLA-DR+ T cells, and CD3+CD8+HLA-DR+ T cells increased markedly in patients with HL vs. healthy controls. Receiver-operating characteristic (ROC) curve analysis showed that CD3+CD4+HLA-DR+ T cells and CD3+CD8+HLA-DR+ T cells each distinguished the high-risk group from the low- and intermediate-risk group. The area under the ROC curve for predicting high-risk patients was 0.795 for CD3+CD4+HLA-DR+ T cell and 0.784 for CD3+CD8+HLA-DR+ T cell. A comparison of peripheral blood T-cell subsets that responded differently to therapy showed significantly higher percentages of CD3+CD4+HLA-DR+ T cells and CD3+CD8+HLA-DR+ T cells in patients who achieved complete remission compared to those who did not achieve complete remission. In addition, high percentages of both CD3+CD4+HLA-DR+ T cells and CD3+CD8+HLA-DR+ T cells were associated with inferior event-free survival. Peripheral immune status may be related to disease severity in HL. CD3+CD4+HLA-DR+ T cells and CD3+CD8+HLA-DR+ T cells may be a novel indicator for risk stratification of HL and may be an independent risk factor for inferior outcome in childhood HL.

Abstract 1984: Baseline T-cell function predicts response to SBRT and immunotherapy in NSCLC

Abstract It is increasingly understood that cancers can be recognized by the immune system and inflammation relates to response. Combining stereotactic radiotherapy (SBRT), to increase release of cancer cell antigens, with an anti-CTLA-4 and PD-L1 inhibitor may lead to increased response rates. No solid biomarker in predicting treatment response is available. We set out to study feasibility of combined durvalumab (anti-PD-L1) and tremelimumab (anti-CTLA-4) with SBRT on the primary tumor. The extend of tumor-infiltrating cells has shown to correlate to improved prognosis using checkpoint inhibitor (CPI) treatment of various cancers. We hypothesized that the peripheral blood T-cell activation status may be a predictor of response, progression free survival (PFS) and overall survival (OS). Methods: Three immunotherapy regimes were combined with SBRT in sequential cohorts as ≥2nd line in CPI naïve patients with NSCLC stage IIIB/IV. One week after the 1st dose of CPI, patients were irradiated on the primary tumor (1x 20Gy on 9cc). The 1st cohort (n=3) received durvalumab, the 2nd and 3rd cohort (both n=6) a combination of durvalumab and tremelimumab, followed by durvalumab monotherapy. Exploratory endpoint was the correlation of response with T-cell function. T-cell function was assessed using flow cytometric analysis of peripheral blood T-cells and compared to simultaneously included healthy controls. In short, whole blood was activated ex vivo using Staphylococcal enterotoxin B (SEB) after which the T-cell activation status was assesses by expression of CD69 and cytokines (IL-2, IFN-γ, TNF-α). Patients were divided in above (responders, R) and below median PFS (non-responders, NR). We compared intracellular cytokine production in both CD4+ and CD8+ T-lymphocytes between both groups and with healthy controls (HC) using the Mann-Whitney U test. Findings: Fifteen patients were included as described above. Median PFS was 2 months, OS 10 months (immature). Baseline characteristics of both groups were comparable. T-cell function was assessed in 14 patients and HC at baseline. Data are shown as median (P-value) for R vs NR below. R had a significant higher percentage activated CD8+ T-cells upon SEB stimulation than NR: CD8+CD69+ 15.8 vs 3.5 (0.008) and IL-2+CD8+CD69+ 8.8 vs 2.9 (0.02). There was a trend in TNF-α+CD8+CD69+ 19.8 vs 8.0 (0.11) and IFN-ɣ+CD8+CD69+ 21.4 vs 5.5 (0.22). These differences were all significant for R compared to HC (p<0.03), but not for NR (P>0.66). Interpretation: With a mild antigen independent stimulus (SEB), the CD8+ T-cells of responders were significantly more activated at baseline compared to non-responders and healthy controls. This suggests an elevated pre-treatment T-cell activation status in patients that responded to the treatment and the possibility to use this as a potential biomarker to predict the response to CPI treatment. Disclosure: This study was sponsored by a research grant from AstraZeneca. Citation Format: Hanneke Kievit, M. Benthe Muntinghe-Wagenaar, Lucie B.M. Hijmering-Kappelle, Birgitta I. Hiddinga, J Fred Ubbels, Robin Wijsman, Bart-Jan Kroesen, Marcel J. van der Leij, A. Rutgers, Harry J. Groen, Huib A. Kerstjens, Anthonie J. van de Wekken, T Jeroen Hiltermann. Baseline T-cell function predicts response to SBRT and immunotherapy in NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1984.

Partner HIV Serostatus Impacts Viral Load, Genital HIV Shedding, and Immune Activation in HIV-Infected Individuals.

Studies of seronegative individuals in HIV discordant relationships provide important insights into the effects of HIV exposure on the seronegative partner, but few have examined the impact of partner serostatus on disease progression in seropositive individuals. We investigated the impact of HIV serostatus on clinical and biological factors influencing HIV disease progression in 337 HIV-infected heterosexual individuals in stable long-term HIV-seroconcordant or HIV-serodiscordant relationships. Seroconcordant individuals had significantly higher plasma viral loads (pVLs) than HIV-infected partners in serodiscordant partnerships [4.4 log10 copies RNA/mL (interquartile range 3.7-5.0) versus 3.9 (3.3-4.5), P < 0.0001], irrespective of gender. pVLs correlated inversely with CD4 T-cell counts, although CD4 counts did not differ significantly between seroconcordant and serodiscordant individuals. HIV+ seroconcordant individuals had higher frequencies of CCR5 CD4 and CD8 T cells (P = 0.03 and P = 0.02, respectively) than HIV+ individuals in serodiscordant relationships and higher concentrations of plasma IL-1β (P = 0.04), TNF-α (P = 0.02), and IL-10 (P = 0.02). Activated CD4 T-cell frequencies and TNF-α were the most influential in determining variation in pVLs, independently of CD4 counts. In addition, HIV+ seroconcordant women had significantly higher genital VLs (gVLs) than HIV+ women in serodiscordant relationships (P < 0.001), with pVLs correlating significantly with gVLs (Rho = 0.65, P < 0.0001). Cervical and blood T-cell activation tended to correlate positively, although partner seroconcordance did not influence genital T-cell activation. We conclude that HIV+ seroconcordant individuals have higher frequencies of activated, CCR5-expressing T cells in blood and higher pVLs and gVLs than their HIV+ counterparts in discordant relationships, which could translate to faster disease progression or larger viral reservoir.

Diagnostic Biomarkers to Diagnose Acute Allograft Rejection After Liver Transplantation: Systematic Review and Meta-Analysis of Diagnostic Accuracy Studies.

Objective: A systematic review and meta-analysis of diagnostic biomarkers for noninvasive diagnosis of acute allograft rejection following liver transplantation.Background: Noninvasive blood and urine markers have been widely explored in recent decades for diagnosing acute rejection after liver transplantation. However, none have been translated into routine clinical use so far due to uncertain diagnostic accuracy, and liver biopsy remains the gold standard.Methods: Systematic literature searches of Medline, Cochrane and Embase were conducted up to February 2019 to identify studies evaluating the use of noninvasive markers in diagnosing allograft rejection following liver transplantation. Meta-analysis was performed using a random effects model with DerSimonian–Laird weighting and the hierarchical summary receiver operating curve.Results: Of 560 identified studies, 15 studies (1,445 patients) met the inclusion criteria. The following markers were tested: acid labile nitroso-compounds (NOx), serum amyloid A protein, procalcitonin, peripheral blood eosinophil count, peripheral blood T-cell activation and interleukin 2 (IL-2) receptor, guanylate-binding protein-2 mRNA, graft-derived cell-free DNA, pi-glutathione S-transferase, alpha-glutathione S-transferase and serum HLA class I soluble antigens. Only eosinophil count was tested in multiple studies, and they demonstrated high heterogeneity (I2 = 72% [95% CI: 0.5–0.99]). IL-2 receptor demonstrated the highest sensitivity (89% [95% CI: 0.78–0.96]) and specificity (81% [95% CI: 0.69–0.89]).Conclusion: IL-2 receptor expression demonstrated the highest diagnostic accuracy, while the peripheral eosinophil count was the only marker tested in more than one study. Presently, liver biopsy remains superior to noninvasive diagnostic biomarkers as most studies exhibited inferior designs, hindering possible translation into clinical application.

Brief Report: Recent Methamphetamine Use Is Associated With Increased Rectal Mucosal Inflammatory Cytokines, Regardless of HIV-1 Serostatus.

Methamphetamine use increases the risk of HIV-1 infection among seronegative users and can exacerbate disease progression in HIV-positive users. The biological mechanisms underlying these associations remain unclear. In this cross-sectional pilot study, we examine the associations between recent methamphetamine use and inflammation in the rectal mucosa and peripheral blood compartments in HIV-1 seropositive and seronegative men who have sex with men. HIV-seronegative and HIV-seropositive men who have sex with men participants were enrolled (N = 24). Recent methamphetamine use was determined by urine drug screen. Cytokines were quantified using multiplex arrays from collected plasma and rectal sponge samples, and peripheral blood T-cell activation was assessed by flow cytometry. Methamphetamine use was associated with consistently increased rectal inflammatory cytokines, specifically interleukin-6 and tumor necrosis factor-alpha, regardless of HIV-1 serostatus in this pilot study. This association was significant after adjusting for age, HIV-serostatus, and receptive anal intercourse frequency using regression analysis. Similar increases were not uniformly observed in peripheral blood. Methamphetamine use is associated with increased local mucosal inflammatory cytokine production. These findings may help explain the increased HIV-1 risk seen in methamphetamine users and contribute to increased inflammation among HIV-seropositive users.

052 Vitiligo is characterized by multi-axis T-cell activation in blood

052 Vitiligo is characterized by multi-axis T-cell activation in blood

CCR5 expression, haplotype and immune activation in protection from infection in HIV-exposed uninfected individuals in HIV-serodiscordant relationships.

Several host factors have been implicated in resistance to HIV infection in individuals who remain HIV-seronegative despite exposure. In a cohort of HIV-serodiscordant heterosexual couples, we investigated interactions between systemic inflammation and T-cell activation in resistance to HIV infection. Males and females in stable long-term relationships with either HIV-infected or uninfected partners were recruited, blood T-cell activation (CD38, HLA-DR, CCR5 and Ki67) and plasma cytokine concentrations were evaluated. The HIV-negative exposed individuals had significantly lower frequencies of CCR5+ CD4+ and CD8+ T cells than unexposed individuals. Mean fluorescence intensity of CCR5 expression on CD4+ T cells was significantly lower in HIV-negative exposed than unexposed individuals. Protective CCR5 haplotypes (HHA/HHF*2, HHF*2/HHF*2, HHC/HHF*2, HHA/HHA, HHA/HHC and HHA/HHD) tended to be over-represented in exposed compared with unexposed individuals (38% versus 28%, P = 0·58) whereas deleterious genotypes (HHC/HHD, HHC/HHE, HHD/HHE, HHD/HHD and HHE/HHE) were under-represented (26% versus 44%; P = 0·16). Plasma concentrations of interleukin-2 (P = 0·02), interferon-γ (P = 0·05) and granulocyte-macrophage colony-stimulating factor (P = 0·006) were lower in exposed compared with unexposed individuals. Activation marker expression and systemic cytokine concentrations were not influenced by gender. We conclude that the dominant signature of resistance to HIV infection in this cohort of exposed but uninfected individuals was lower T-cell CCR5 expression and plasma cytokine concentrations.

Human Immunodeficiency Virus Persistence and T-Cell Activation in Blood, Rectal, and Lymph Node Tissue in Human Immunodeficiency Virus-Infected Individuals Receiving Suppressive Antiretroviral Therapy.

Immune activation and inflammation remain elevated in human immunodeficiency virus (HIV)-infected individuals receiving antiretroviral therapy (ART) and may contribute to HIV persistence. Using flow cytometry expression of CD38, HLA-DR and PD-1 were measured in blood (n = 48), lymph node (LN; n = 9), and rectal tissue (n = 17) from virally suppressed individuals. Total and integrated HIV DNA, 2-LTR circles, and cell-associated unspliced HIV RNA were quantified. CD4+ T cells from rectal tissue had a higher frequency of integrated HIV DNA compared with blood (4.26 fold-change in DNA; 95% confidence interval [CI] = 2.61-7.00; P < .001) and LN (2.32 fold-change in DNA; 95% CI = 1.22-4.41; P = .01). In rectal tissue, there were positive associations between integrated HIV DNA with PD-1+ CD4+ T-cells (1.44 fold-change in integrated HIV DNA per 10-unit increase in PD-1+ CD4+ T cells; 95% CI = 1.01-2.05; P = .045) and CD38+HLA-DR+ CD8+ T cells (1.40 fold-change in integrated HIV DNA per 1-unit increase in CD38+HLA-DR+ CD8+ T cells; 95% CI = 1.05-1.86; P = .02). Both associations were independent of current and nadir CD4+ T-cell counts. During ART, rectal tissue is an important reservoir for HIV persistence with a high frequency of activated CD4+ and CD8+ T cells. PD-1 may represent a marker of HIV persistence in rectal tissue.

Systemic Immune Activation and HIV Shedding in the Female Genital Tract.

Plasma HIV RNA is the most significant determinant of cervical HIV shedding. However, shedding is also associated with sexually transmitted infections (STIs) and cervical inflammation. The mechanism by which this occurs is poorly understood. There is evidence that systemic immune activation promotes viral entry, replication, and HIV disease progression. We hypothesized that systemic immune activation would be associated with an increase in HIV genital shedding. Clinical assessments, HIV RNA in plasma and genital secretions, and markers of immune activation (CD38(+)DR(+) and CD38(-)DR(-)) on CD4(+) and CD8(+) T cells in blood were evaluated in 226 HIV+ women enrolled in the Women's Interagency HIV Study. There were 569 genital evaluations of which 159 (28%) exhibited HIV RNA shedding, defined as HIV viral load >80 copies per milliliter. We tested associations between immune activation and shedding using generalized estimating equations with logit link function. In the univariate model, higher levels of CD4(+) and CD8(+) T-cell activation in blood were significantly associated with genital tract shedding. However, in the multivariate model adjusting for plasma HIV RNA, STIs, and genital tract infections, only higher levels of resting CD8(+) T cells (CD38(-)DR(-)) were significantly inversely associated with HIV shedding in the genital tract (odds ratios = 0.44, 95% confidence interval: 0.21 to 0.9, P = 0.02). The association of systemic immune activation with genital HIV shedding is multifactorial. Systemic T-cell activation is associated with genital tract shedding in univariate analysis but not when adjusting for plasma HIV RNA, STIs, and genital tract infections. In addition, women with high percentage of resting T cells are less likely to have HIV shedding compared with those with lower percentages. These findings suggest that a higher percentage of resting cells, as a result of maximal viral suppression with treatment, may decrease local genital activation, HIV shedding, and transmission.

Immunomodulation of human intestinal T cells by the synthetic CD80 antagonist RhuDex®.

Deregulated activation of mucosal lamina propria T cells plays a central role in the pathogenesis of intestinal inflammation. One of the means to attenuate T cell activation is by blocking the CD28/CD80 co-stimulatory pathway. Here we investigate RhuDex®, a small molecule that binds to human CD80, for its effects on the activation of lamina propria T cells employing a gut-culture model of inflammation. To this end, lamina propria leukocytes (LPL) and peripheral blood lymphocytes (PBL) were stimulated either through the CD3/T-cell-receptor complex or the CD2-receptor (CD2) employing agonistic monoclonal antibodies. Co-stimulatory signals were provided by CD80/CD86 present on lamina propria myeloid cells or LPS-activated peripheral blood monocytes. Results show that RhuDex® caused a profound reduction of LPL and PBL proliferation, while Abatacept (CTLA-4-Ig) inhibited LPL proliferation to a small degree, and had no effect on PBL proliferation. Furthermore, Abatacept significantly inhibited IL-2, TNF-α, and IFN-γ release from LPL, primarily produced by CD4+ T cells, where IL-2 blockage was surprisingly strong, suggesting a down-regulating effect on regulatory T cells. In contrast, in the presence of RhuDex®, secretion of IL-17, again mostly by CD4+ T cells, and IFN-γ was inhibited in LPL and PBL, yet IL-2 remained unaffected. Thus, RhuDex® efficiently inhibited lamina propria and peripheral blood T-cell activation in this pre-clinical study making it a promising drug candidate for the treatment of intestinal inflammation.

CD8+/CD161++ mucosal-associated invariant T-cell levels in the colon are restored on lsong-term antiretroviral therapy and correlate with CD8+ T-cell immune activation

Mucosal-associated invariant T (MAIT) cells are tissue-homing T cells recently implicated in HIV pathogenesis. We found that the proportion of MAIT cell in blood and colon of HIV+ patients are reduced in untreated infection. Antiretroviral therapy restored colonic but not blood MAIT cell percentages. We observed a negative correlation between colonic MAIT cells and T-cell activation in blood and suggest mucosal MAIT cell depletion may contribute to systemic immune activation in HIV infection.

Abstract 62: Cholesterol Efflux Pathways in Dendritic Cells Suppress Autoimmune Responses

Patients with auto-immune disorders have low HDL levels. Mice deficient in genes regulating cholesterol homeostasis, such as liver X receptor (LXR) or apolipoprotein A1 (apoA1), show an autoimmune phenotype. LXR regulates the expression of ATP Binding Cassette A1 and G1 (ABCA1 and ABCG1) that mediate cholesterol efflux to apoA1 and HDL. ABCG1 is highly expressed in dendritic cells (DCs). We hypothesized that ABCA1 and ABCG1 regulate autoimmunity. On a chow diet, 40 weeks old Abca1-/-Abcg1-/- mice showed enlarged lymph nodes (LNs), increased plasma auto-antibodies to dsDNA, and glomerulonephritis, with characteristics typical for lupus nephritis. Using the Cre loxP system, we investigated whether these effects were due to Abca1/g1 deficiency in T-cells, macrophages, or DCs. Only Abca1/g1 deficiency in DCs in CD11cCreAbca1fl/flAbcg1fl/fl mice replicated the auto-immune phenotype found in Abca1-/-Abcg1-/- mice. This suggests a major role for DC cholesterol homeostasis in autoimmunity. DCs present antigens to T-cells, leading to their activation. CD11cCreAbca1fl/flAbcg1fl/fl mice showed increased T-cell activation in blood, spleen, and LNs. After immunization, DCs from CD11cCreAbca1fl/flAbcg1fl/fl mice showed increased antigen presentation to T-cells in vitro and in vivo. CD11cCreAbca1fl/flAbcg1fl/fl mice had increased CD80+ DCs. CD80 is a co-stimulatory molecule required for antigen presentation. Abca1/g1 deficiency in DCs increased endosomal cholesterol accumulation in vitro. Ligands for Toll like receptor (TLR) 3 and 4 increased CD80 mRNA in CD11cCreAbca1fl/flAbcg1fl/fl compared to Abca1fl/flAbcg1fl/fl DCs, where the effect of ligands for TLR3&gt;TLR4. Cholesterol depletion by cyclodextrin decreased CD80 mRNA and antigen presentation in CD11cCreAbca1fl/flAbcg1fl/fl DCs in vitro. The increased CD80 mRNA in CD11cCreAbca1fl/flAbcg1fl/fl DCs was also reversed by a type I interferon (IFN) antibody, suggesting excessive signaling by the known TLR3-IFN-CD80 axis. These studies show for the first time a role for cholesterol efflux pathways in DCs in maintaining immune tolerance.

An altered intestinal mucosal microbiome in HIV-1 infection is associated with mucosal and systemic immune activation and endotoxemia.

HIV-1 infection disrupts the intestinal immune system, leading to microbial translocation and systemic immune activation. We investigated the impact of HIV-1 infection on the intestinal microbiome and its association with mucosal T cell and dendritic cell (DC) frequency and activation, as well as with levels of systemic T cell activation, inflammation and microbial translocation. Bacterial 16S ribosomal DNA sequencing was performed on colon biopsies and fecal samples from subjects with chronic, untreated HIV-1 infection and uninfected control subjects. Colon biopsies of HIV-1 infected subjects had increased abundances of Proteobacteria and decreased abundances of Firmicutes compared to uninfected donors. Furthermore at the genus level, a significant increase in Prevotella and decrease in Bacteroides was observed in HIV-1 infected subjects, indicating a disruption in the Bacteroidetes bacterial community structure. This HIV-1-associated increase in Prevotella abundance was associated with increased numbers of activated colonic T cells and myeloid DCs. Principal coordinates analysis demonstrated an HIV-1-related change in the microbiome that was associated with increased mucosal cellular immune activation, microbial translocation and blood T cell activation. These observations suggest that an important relationship exists between altered mucosal bacterial communities and intestinal inflammation during chronic HIV-1 infection.

Associations between Virologic and Immunologic Dynamics in Blood and in the Male Genital Tract

To determine the influence of asymptomatic genital viral infections on the cellular components of semen and blood, we evaluated the associations between the numbers and activation statuses of CD4+ and CD8+ T lymphocytes in both compartments and the seminal levels of cytomegalovirus (CMV), herpes simplex virus (HSV), and human immunodeficiency virus 1 (HIV). Paired blood and semen samples were collected from 36 HIV-infected antiretroviral-naïve individuals and from 40 HIV-uninfected participants. We performed multiparameter flow cytometry analysis (CD45, CD45RA, CD3, CD4, CD8, and CD38) of seminal and blood cellular components and measured HIV RNA and CMV and HSV DNA levels in seminal and blood plasma by real-time PCR. Compared to HIV-uninfected participants, in the seminal compartment HIV-infected participants had higher levels of CMV (P < 0.05), higher numbers of total CD3+ (P < 0.01) and CD8+ subset (P < 0.01) T lymphocytes, and higher CD4+ and CD8+ T lymphocyte activation (RA-CD38+) (P < 0.01). Seminal CMV levels positively correlated with absolute numbers of CD4+ and CD8+ T cells in semen (P < 0.05) and with the activation status of CD4+ T cells in semen and in blood (P < 0.01). HIV levels in semen (P < 0.05) and blood (P < 0.01) were positively associated with T-cell activation in blood. Activation of CD8+ T cells in blood remained an independent predictor of HIV levels in semen in multivariate analysis. The virologic milieu in the male genital tract strongly influences the recruitment and activation of immune cells in semen and may also modulate T-cell immune activation in blood. These factors likely influence replication dynamics, sexual transmission risk, and disease outcomes for all three viruses.

Antiretroviral Treatment Effect on Immune Activation Reduces Cerebrospinal Fluid HIV-1 Infection

To define the effect of antiretroviral therapy (ART) on activation of T cells in cerebrospinal fluid (CSF) and blood, and interactions of this activation with CSF HIV-1 RNA concentrations. Cross-sectional analysis of 14 HIV-negative subjects and 123 neuroasymptomatic HIV-1-infected subjects divided into 3 groups: not on ART (termed "offs"), on ART with plasma HIV-1 RNA >500 copies/mL ("failures"), and on ART with plasma HIV-1 RNA <or=500 copies/mL ("successes"). T-cell activation was measured by coexpression of CD38 and human leukocyte antigen DR (HLA-DR). Other measurements included CSF neopterin and white blood cell (WBC) counts. CD8 T-cell activation in CSF and blood was highly correlated across all subjects and was highest in the offs, lower in the failures, and lower still in the successes. While CD8 activation was reduced in failures compared to offs across the range of plasma HIV-1, it maintained a coincident relation to CSF HIV-1 in both viremic groups. In addition to correlation with CSF HIV-1 concentrations, CD8 activation in blood and CSF correlated with CSF WBCs and CSF neopterin. Multivariate analysis confirmed the association of blood CD8 T-cell activation, along with plasma HIV-1 RNA and CSF neopterin, with CSF HIV-1 RNA levels. The similarity of CD8 T-cell activation in blood and CSF suggests these cells move from blood to CSF with only minor changes in CD38/HLA-DR expression. Differences in the relation of CD8 activation to HIV-1 concentrations in the blood and CSF in the 2 viremic groups suggest that changes in immune activation not only modulate CSF HIV-1 replication but also contribute to CSF treatment effects. The magnitude of systemic HIV-1 infection and intrathecal macrophage activation are also important determinants of CSF HIV-1 RNA levels.

T Regulatory Cells in Stable Posttransplant Bronchiolitis Obliterans Syndrome

Obliterative bronchiolitis (OB), mainly mediated by T cells, remains the major cause of morbidity and death in long-term lung transplant. Acute rejection (AR), also a T-cell mediated process, is strongly linked to OB. For unknown reasons, several patients with OB halt their pulmonary function decline and stabilize their obstructive defect for a long period. Our aim was to assess the T-cell activation in blood, induced sputum, and broncho-alveolar lavage during AR, stable OB (sOB), and evolving OB (eOB). T-cell phenotype and cytokine production were assessed by flow cytometry in these three compartments. Interleukin-4, interferon-gamma and transforming growth factor (TGF)-beta levels were measured by enzyme-linked immunosorbent assay in blood cell culture supernatants. Results were compared between healthy lung transplant recipients and AR (n=7), sOB (n=7), and eOB (n=13). Stable and evolutive OB were characterized by a Treg, Th1, and Th2 activation, but compared to eOB, Treg and Th2 cells predominated in sOB. A clear Th1 activation was observed in AR. TGF-beta was increased in AR and evolving OB. These preliminary results indicate a contrasted T-cell activation profile depending on the clinical conditions. We speculate that Treg cells could counterbalance the Th0 activation seen in evolving OB and participate in stabilization of airway obstruction.

Atheroprotective Effect of CD31 Receptor Globulin Through Enrichment of Circulating Regulatory T-Cells

This study was designed to evaluate whether replacing CD31 (PECAM-1) signaling can restore the regulation of lymphocyte activation and improve experimental atherosclerosis. Atherosclerosis, the principal cause of myocardial infarction and stroke, is due to the development of a pathogenic immune response within the vascular wall and is aggravated by the reduction of regulatory T-cells. CD31, a transmembrane adhesion molecule with inhibitory signaling functions, is physiologically expressed on blood and vascular resting cells but is lost in pathologic conditions associated with atherosclerosis. Replacement therapy with a CD31 receptor globulin (Rg) was delivered by in vivo gene transfer in 6-week-old apolipoprotein E knockout mice (n = 14 per group) every 5 weeks for 6 months. Control groups were treated with a truncated CD31Rg or with vehicle alone. At the end of the study, plaque size and morphology and blood T-cell compartment were analyzed in all mice. Atherosclerotic lesions of CD31Rg-treated mice were smaller (p < 0.01) and showed less neovascularization and intraplaque hemorrhage (p < 0.05) compared with control subjects. Furthermore, circulating regulatory T-cells were increased in vivo (p < 0.01) and showed normal suppressive function on proliferation of conventional T-cells in vitro. Indeed, CD31Rg treatment led to blunted blood T-cell activation (p < 0.05) and reduced T-cell infiltration within plaques (p < 0.01). Our data suggest that CD31 plays a key role in the regulation of the immune response linked to atherosclerosis. CD31-targeting therapeutic approaches may therefore be envisaged for preventing and treating atherosclerotic diseases.

Primary Simian Immunodeficiency Virus SIVmnd-2 Infection in Mandrills ( Mandrillus sphinx )

Mandrills are the only nonhuman primate (NHP) naturally infected by two types of simian immunodeficiency virus (SIV): SIVmnd-1 and SIVmnd-2. We have already reported that the high SIVmnd-1 replication during primary infection contrasts with only transient changes in CD4+ and CD8+ cell counts. Since early virus-host interactions predict viral control and disease progression in human immunodeficiency virus-infected patients, we investigated the dynamics of SIVmnd-2 primary infection in mandrills to examine the impact on immune effectors in blood and lymph nodes (LNs). To avoid in vitro strain selection, all mandrills in this study received plasma from SIVmnd-2-infected mandrills. SIVmnd-2 plasma viremia peaked at 10(7) to 10(8) RNA copies/ml between days 7 and 10. This peak was followed in all four monkeys by a decline in virus replication, with a set point level of 10(5) to 10(6) RNA copies/ml at day 42 postinfection (p.i.). Viral DNA load in PBMC and LNs also peaked between days 7 and 10 (10(5) to 10(6) DNA copies/10(6) cells) and stabilized at 10(3) to 10(4) DNA copies/10(6) cells during the chronic phase. Anti-SIVmnd-2 antibodies were detected starting from days 28 to 32. A transitory decline of CD3+ CD4+ cells in the LNs occurred in animals with high peak VLs. CD4+ and CD8+ T-cell activation in blood and LNs was noted between days 5 and 17 p.i., surrounding the peak of viral replication. This was most significant in the LNs. Activation markers then returned to preinfection values despite continuous and active viral replication during the chronic infection. The dynamics of SIVmnd-2 infection in mandrills showed a pattern similar to that of SIVmnd-1 infection. This might be a general feature of nonpathogenic SIV natural African NHP models.

Association of CD26 with CD45RA outside lipid rafts attenuates cord blood T-cell activation

AbstractCD26 is a T-cell activation antigen that contains dipeptidyl peptidase IV activity and binds adenosine deaminase. Recent work showed that specialized membrane microdomains, also known as lipid rafts, play a key role in T-cell signaling. In this study, we investigate the role of CD26 in cord blood T-cell activation and signal transduction. We demonstrated that different expression levels of CD26 were observed between cord blood T cells (CBTCs) and peripheral blood T cells (PBTCs) and that CD26+CD45RA+ CBTCs were different compared with CD26+CD45RA+ PBTCs. Moreover, the comitogenic effect of CD26 was not as pronounced in CBTCs as in PBTCs. We also showed that CD26 cross-linking induced less phosphorylation of T-cell receptor-signaling molecules, lymphoid T-cell protein tyrosine kinase (Lck), zeta-associated protein 70 (ZAP-70), T-cell receptor ζ (TCRζ), and linker for activator of T cells (LAT) in CBTCs than in PBTCs. Furthermore, CD26 molecules associated with CD45RA molecules outside lipid rafts in CBTCs. Our results suggest that strong physical linkage of CD26 with CD45RA outside lipid rafts may be responsible for the attenuation of T-cell activation signaling through CD26, which may be responsible for immature immune response and the low incidence of severe graft-versus-host disease in cord blood transplantation. (Blood. 2004;103:1002-1010)