Predominant involvement of CD8+CD28- lymphocytes in human immunodeficiency virus-specific cytotoxic activity

Frequency of Class I HLA-Restricted Anti-HIV CD8+ T Cells in Individuals Receiving Highly Active Antiretroviral Therapy (HAART)

Peptide/MHC tetrameric complexes were used to enumerate the frequency of HLA class I-restricted epitope-specific CD8+ T cells in 18 HLA-A*0201 HIV type 1-infected asymptomatic patients. HLA-A*0201 molecules were complexed to HIV Gag p17 (amino acids 77–85) and reverse transcriptase (amino acids 464–472) peptides, biotinylated, and bound to streptavidin-phycoerythrin to form tetramers. We show in this study that 17 of 18 HIV-1-infected asymptomatic patients have circulating frequencies of 1/50–1/1000 CD8+ T cells that recognize both Gag and Pol CTL epitopes or either epitope alone. The functional nature of these cells is open to interpretation, as we show that despite relatively high frequencies of fresh epitope-specific CD8+ T cells, variant epitope sequences in viral plasma progeny were rare. In addition, the majority of tetramer-positive cells did not display discernible fresh CTL activity; only after restimulation with specific peptide in culture was there an expansion of epitope-specific CD8+ cells, correlating with high CTL activity. These data suggest that fresh tetramer-stained cells probably represent memory precursors; we demonstrate, with the application of highly active antiretroviral therapy, that the interruption of chronic antigenic stimulation causes significant reductions in the frequency of these cells in five of six patients. In conclusion, this study provides evidence that persistently replicating viral populations are probably required to maintain high frequencies of HIV-1 epitope-specific CD8+ T cells in asymptomatic chronically infected individuals

Direct Analysis of Viral-Specific CD8+ T Cells with Soluble HLA-A2/Tax11-19 Tetramer Complexes in Patients with Human T Cell Lymphotropic Virus-Associated Myelopathy

Human T cell lymphotropic virus-I (HTLV-I)-associated myelopathy is a slowly progressive neurologic disease characterized by inflammatory infiltrates in the central nervous system accompanied by clonal expansion of HTLV-I-reactive CD8+ T-cells. In patients carrying the HLA-A2 allele, the immune response is primarily directed to the Tax11-19 peptide. The frequency, activation state, and TCR usage of HLA-A2/Tax11-19 binding T cells in patients with HTLV-I-associated myelopathy was determined using MHC class I tetramers loaded with the Tax11-19 peptide. Circulating Tax11-19-reactive T cells were found at very high frequencies, approaching 1:10 circulating CD8+ T cells. T cells binding HLA-A2/Tax11-19 consisted of heterogeneous populations expressing different chemokine receptors and the IL-2R β-chain but not the IL-2R α-chain. Additionally, Tax11-19-reactive CD8+ T cells used one predominant TCR Vβ-chain for the recognition of the HLA-A2/Tax11-19 complex. These data provide direct evidence for high frequencies of circulating Tax11-19-reactive CD8+ T cells in patients with HTLV-I-associated myelopathy.

Comparative analysis of cytotoxic T lymphocytes in lymph nodes and peripheral blood of simian immunodeficiency virus-infected rhesus monkeys

Most studies of human immunodeficiency virus type 1 (HIV-1)-specific cytotoxic T lymphocytes (CTL) have been confined to the evaluation of these effector cells in the peripheral blood. What has not been clear is the extent to which CTL activity in the blood actually reflects this effector cell function in the lymph nodes, the major sites of HIV-1 replication. To determine the concordance between CTL activity in lymph nodes and peripheral blood lymphocytes (PBL), CTL specific for simian immunodeficiency virus of macaques (SIVmac) have been characterized in lymph nodes of infected, genetically selected rhesus monkeys by using both Gag peptide-specific functional CTL assays and tetrameric peptide-major histocompatibility complex (MHC) class I molecule complex staining techniques. In studies of six chronically SIVmac-infected rhesus monkeys, Gag epitope-specific functional lytic activity and specific tetrameric peptide-MHC class I staining were readily demonstrated in lymph node T lymphocytes. Although the numbers of tetramer-binding cells in some animals differed from those documented in their PBL, the numbers of tetramer-binding cells from these two different compartments were not statistically different. Phenotypic characterization of the tetramer-binding CD8(+) lymph node T lymphocytes of the infected monkeys demonstrated a high level of expression of the activation-associated adhesion molecules CD11a and CD49d, the Fas molecule CD95, and MHC class II-DR. These studies documented a low expression of the naive T-cell marker CD45RA and the adhesion molecule CD62L. This phenotypic profile of the tetramer-binding lymph node CD8(+) T cells was similar to that of tetramer-binding CD8(+) T cells from PBL. These observations suggest that characterization of AIDS virus-specific CTL activity by sampling of cells in the peripheral blood should provide a reasonable estimation of CTL in an individual's secondary lymphoid tissue.

Altered ex vivo balance between CD28+ and CD28- cells within HIV-specific CD8+ T cells of HIV-seropositive patients

The CD8+CD28- cell population in the blood of HIV-infected individuals is considerably expanded. Yet the cause of this expansion is not clear. The recent demonstration of identical TCR-rearranged genes in CD8+CD28+ and CD8+CD28- expanded T cells of HIV-seropositive patients supports the hypothesis that these two subpopulations are phenotypic variants of the same lineage. To further elucidate the precise relationship between them, we measured the fraction of CD28+ and CD28- T cell subsets in IFN-gamma-producing CD8+ T cells by intracellular staining and cytofluorometry as a functional test for ex vivo recognition of epitopes derived from HIV-1, Epstein-Barr virus (EBV) and influenza virus. HIV-specific CD8+ T cells were predominantly CD28 in all the eight HIV-seropositive subjects tested. In contrast, the anti-EBV and anti-influenza CD8+ T cells were mainly CD28+ in these patients as well as in HIV-seronegative individuals. This supports the notion that the CD8 CD28 hyperlymphocytosis observed in HIV infection is due mainly to chronic activation and differentiation of HIV-specific memory CD8+CD28+ T cells into terminally differentiated CD8+CD28-lymphocytes, because of intense HIV-1 replication and without any important bystander activation. This clarification of the mechanisms underlying the CD8+CD28- expansion in HIV-induced pathogenesis may have important therapeutic implications.

Immunophenotypic Analysis of Peripheral Blood Mononuclear Cells Undergoing In Vitro Apoptosis After Isolation From Human Immunodeficiency Virus–Infected Children

Lymphocytes of human immunodeficiency virus (HIV)-infected individuals undergo accelerated apoptosis in vitro, but the subsets of cells affected have not been clearly defined. This study examined the relationship between lymphocyte phenotype and apoptotic cell death in HIV-infected children by flow cytometry. Direct examination of the phenotype of apoptotic lymphocytes was accomplished using a combination of surface antigen labeling performed simultaneously with the Tdt mediated Utp nick end-labeling (TUNEL) assay. In comparison to live cells, apoptotic lymphocytes displayed an overrepresentation of CD45RO and HLA-DR expressing cells, while CD28 and CD95 expressing cells were underrepresented. Lymphocytes expressing CD4, CD8, and CD38 were equally represented in apoptotic and live populations. When percent lymphocyte apoptosis follow- ing culture was examined independently with lymphocyte subsets in fresh blood, apoptosis was negatively correlated with the percentage of CD4 cells, but not with specific CD4 T-cell subsets. Although not correlated with the percentage of total CD8 cells, apoptosis was positively correlated with specific CD8 T-cell subsets expressing CD45RO and CD95 and negatively correlated for CD8 T cells expressing CD45RA. These results provide direct evidence that a population of activated lymphocytes with the memory phenotype lacking the costimulatory molecule CD28 are especially prone to undergo apoptosis. The findings related to CD95 expression in fresh and apoptotic cells implicate Fas-dependent and Fas-independent pathways of apoptosis in HIV disease in children.

Immunophenotypic Analysis of Peripheral Blood Mononuclear Cells Undergoing In Vitro Apoptosis After Isolation From Human Immunodeficiency Virus–Infected Children

Lymphocytes of human immunodeficiency virus (HIV)-infected individuals undergo accelerated apoptosis in vitro, but the subsets of cells affected have not been clearly defined. This study examined the relationship between lymphocyte phenotype and apoptotic cell death in HIV-infected children by flow cytometry. Direct examination of the phenotype of apoptotic lymphocytes was accomplished using a combination of surface antigen labeling performed simultaneously with the Tdt mediated Utp nick end-labeling (TUNEL) assay. In comparison to live cells, apoptotic lymphocytes displayed an overrepresentation of CD45RO and HLA-DR expressing cells, while CD28 and CD95 expressing cells were underrepresented. Lymphocytes expressing CD4, CD8, and CD38 were equally represented in apoptotic and live populations. When percent lymphocyte apoptosis follow- ing culture was examined independently with lymphocyte subsets in fresh blood, apoptosis was negatively correlated with the percentage of CD4 cells, but not with specific CD4 T-cell subsets. Although not correlated with the percentage of total CD8 cells, apoptosis was positively correlated with specific CD8 T-cell subsets expressing CD45RO and CD95 and negatively correlated for CD8 T cells expressing CD45RA. These results provide direct evidence that a population of activated lymphocytes with the memory phenotype lacking the costimulatory molecule CD28 are especially prone to undergo apoptosis. The findings related to CD95 expression in fresh and apoptotic cells implicate Fas-dependent and Fas-independent pathways of apoptosis in HIV disease in children.

Cloning of BY55, a Novel Ig Superfamily Member Expressed on NK Cells, CTL, and Intestinal Intraepithelial Lymphocytes

Expression of the BY55 protein has been shown to be tightly associated with NK and CD8+ T lymphocytes with cytolytic effector activity. To determine the function of this protein, we molecularly cloned BY55 cDNA. The cDNA sequence predicts a cysteine-rich, glycosylphosphatidylinositol-anchored protein of 181 amino acids with a single Ig-like domain weakly homologous to killer inhibitory receptors. Reduction and carboxyamidomethylation of immunoprecipitated BY55 gave a band of 27 kDa, whereas reduction alone led to an 80-kDa species, suggesting that BY55 is a tightly disulfide-linked multimer. RNA blot analysis revealed BY55 mRNAs of 1.5 and 1.6 kb whose expression was highly restricted to NK and T cells. BY55 was expressed on the CD56dim, CD16+ subset of NK cells, which have high cytolytic activity, but was not expressed and was not induced on the CD56bright, CD16− subset of NK cells, a subset with high proliferative, but low cytolytic, capacity. In human tissues, BY55 mRNA was expressed only in spleen, PBL, and small intestine (in gut lymphocytes). BY55 was expressed on all intestinal intraepithelial lymphocytes, which were predominantly CD3+TCRα/β+CD4−CD8+CD11b+CD28−CD45RO+CD56−CD101+CD103+ (αEβ7 integrin). In addition, BY55 was expressed on most CD8+CD28− peripheral blood T cells. These phenotypic relationships suggest that CD8+CD28+ precursor CTL may terminally differentiate into CD8+CD28−BY55+ effector CTL and that some of the peripheral blood CD8+CD28− subset may represent recirculation from mucosal epithelial immune sites.

Changes in blood CD8+ lymphocyte activation status and plasma HIV RNA levels during antiretroviral therapy

OBJECTIVE

To analyse the relationship between CD8+ lymphocyte phenotype alterations and plasma HIV RNA levels in HIV-infected patients treated with the zidovudine-didanosine combination.

METHODS

A total of 30 HIV-infected patients who had never received antiretroviral therapy and who were starting treatment with a combination of zidovudine and didanosine were prospectively studied. Multiparameter flow cytometric analysis of CD8+ lymphocytes and plasma HIV RNA determination were performed on day 0, day 15 and monthly from months 1 to 6.

RESULTS

Patients were divided into three categories according to the time-course of plasma HIV RNA levels. In 14 patients, an early and sustained fall in plasma HIV RNA to below the detection limit (500 copies/ml) was observed; in 10 patients, the fall was transient; in six patients, plasma HIV RNA was always detectable (non-responders). The mean CD4+ lymphocyte gain was 120 x 10(6)/l at month 6 in sustained and transient responders, and 55 x 10(6)/l in non-responders. A significant fall in the proportion of CD8+ lymphocytes with an activated phenotype was observed only in the two groups of responders, and was higher in the sustained responders (CD38+HLA-DR+, -56.8%; CD38+CD45RO+, -54.0%; HLA-DR+CD45RO+, -48.4%; CD38+CD28-, -47.3%).

CONCLUSION

A fall in the proportion of activated CD8+ lymphocytes is associated with the disappearance of HIV RNA from plasma during antiretroviral therapy. Undetectable plasma HIV RNA is not associated with a return to normal CD8+ lymphocyte activation status after 6 months of treatment, suggesting that viral replication persists in lymphoid tissues.

Expression of adhesion molecules and CD28 on T lymphocytes during human immunodeficiency virus infection

Adhesion molecules, which play a major role in lymphocyte circulation, have not been well characterized in human immunodeficiency virus (HIV) infection. T-lymphocyte populations, including CD3, CD4, CD28, and adhesion molecules (L selectin, LFA-1, VLA-4, and ICAM-1) were measured by flow cytometry in a cross-sectional study of 100 HIV-infected and 49 HIV-seronegative adults. HIV-infected adults had lower numbers of CD3+ lymphocytes expressing L selectin (P < 0.0001) and VLA-4 (P < 0.01) and higher numbers of CD3+ lymphocytes expressing LFA-1bright (P < 0.002) than did HIV-negative adults. By CD4+-lymphocyte count category (>500, 200 to 500, or <200 cells/microl), HIV-infected adults with more advanced disease had lower percentages of CD3+ lymphocytes expressing L selectin and VLA-4 and higher percentages of CD3+ lymphocytes expressing LFA-1. The percentages of CD3+ CD28+ lymphocytes and of CD3+ L selectin+ lymphocytes were positively correlated (Spearman coefficient = 0.86; P < 0.0001), and the percentage of CD3+ CD28+ lymphocytes and the CD3+ LFA-1bright lymphocyte/CD3+ LFA-1dim lymphocyte ratio were negatively correlated (Spearman coefficient = -0.92; P < 0.00001). The results of this study suggest that HIV infection is associated with altered expression of adhesion molecules.

Impact on the immune system of undetectable plasma HIV-1 RNA for more than 2 years

OBJECTIVE

To investigate the impact of prolonged HIV suppression on the immune system by analysing the expression of several lymphocyte surface markers in a group of HIV-1-infected patients who maintained undetectable HIV-1 RNA levels for more than 24 months.

PATIENTS AND METHODS

The study included a highly selected group of nine HIV-1-infected asymptomatic subjects and seven HIV-1-seronegative controls. The inclusion criteria of HIV-1-infected patients was to have plasma HIV-1 RNA levels below 20 (1.3 log10) copies/ml for at least 24 months while under antiretroviral treatment with nucleoside analogues. The patient population was retrospectively taken from a cohort of 1418 treated subjects. Mean initial absolute CD4+ T-cell count and percentage were 468+/-234 x 10(6)/l (range, 202-935 x 10(6)/l) and 25+/-6% (range, 16-33%), respectively. Plasma HIV-1 RNA quantification was determined using a standard and ultrasensitive reverse transcriptase polymerase chain reaction assay. Median HIV-1 RNA plasma level before antiretroviral treatment was 3.14 log10 copies/ml (range, 1.74-3.73 log10 copies/ml). Two or three-colour immunophenotyping was performed on whole blood and frozen peripheral blood mononuclear cells by flow cytometry.

RESULTS

A significant increase was noted in CD4+ lymphocyte counts at the end of the study in HIV-1-positive patients. In addition, the CD4: CD8 ratio rose significantly with respect to baseline, although it remained lower than in the controls. CD45RA+ and CD45RO+ population percentages did not differ between groups. A significant rise in CD45RA+ T cells was observed. Analysis of T-cell activation measuring the expression of human leukocyte antigen-DR and CD25 did not differ between groups. The proportion of CD8+ lymphocytes that were CD28+ was similar in both groups at the end of the follow-up. T-cell receptor Vbeta subfamily analysis showed that an expansion of the T-cell receptor repertoire might occur in these patients.

CONCLUSION

Patients who maintain undetectable viral load for prolonged periods of time with antiretroviral therapy may achieve a partial immune restoration of the immune system. Our results suggest that treatment of patients at early stages of HIV infection is warranted.

Analysis of Gag-specific cytotoxic T lymphocytes in simian immunodeficiency virus-infected rhesus monkeys by cell staining with a tetrameric major histocompatibility complex class I-peptide complex

A tetrameric recombinant major histocompatibility complex (MHC) class I-peptide complex was used as a staining reagent in flow cytometric analyses to quantitate and define the phenotype of Gag-specific cytotoxic T lymphocytes (CTLs) in the peripheral blood of simian immunodeficiency virus macaque (SIVmac)-infected rhesus monkeys. The heavy chain of the rhesus monkey MHC class I molecule Mamu-A*01 and beta2-microglobulin were refolded in the presence of an SIVmac Gag synthetic peptide (p11C, C-M) representing the optimal nine-amino acid peptide of Mamu-A*01-restricted predominant CTL epitope to create a tetrameric Mamu-A*01/p11C, C-M complex. Tetrameric Mamu-A*01/p11C, C-M complex bound to T cells of SIVmac-infected, Mamu-A*01(+), but not uninfected, Mamu-A*01(+), or infected, Mamu-A*01(-) rhesus monkeys. Specific staining of peripheral blood mononuclear cells (PBMC) from SIVmac-infected, Mamu-A*01(+) rhesus monkeys was only found in the cluster of differentiation (CD)8alpha/beta+ T lymphocyte subset and the percentage of CD8alpha/beta+ T cells in the peripheral blood of four SIVmac-infected, Mamu-A*01+ rhesus monkeys staining with this complex ranged from 0.7 to 10.3%. Importantly, functional SIVmac Gag p11C-specific CTL activity was seen in sorted and expanded tetrameric Mamu-A*01/p11C, C-M complex-binding, but not nonbinding, CD8alpha/beta+ T cells. Furthermore, the percentage of CD8alpha/beta+ T cells binding this tetrameric Mamu-A*01/p11C, C-M complex correlated well with p11C-specific cytotoxic activity as measured in both bulk and limiting dilution effector frequency assays. Finally, phenotypic characterization of the cells binding this tetrameric complex indicated that this lymphocyte population is heterogeneous. These studies indicate the power of this approach for examining virus-specific CTLs in in vivo settings.

CD28 expression in T cell aging and human longevity

Functional decrements of the immune system have a major contribution to aging and age-related diseases. Here, we further characterize the decline in proportion of CD28-positive T cells previously identified in centenarians. Cohorts of 97 centenarians, 40 subjects aged 70-90 (ELD group), and 40 young adults (under age 40) were phenotyped for T cell surface expression of CD28, CD4, and CD8 antigens. The significant decline in T cells expressing CD28 (p < 10(-4) for comparisons between adults and either ELD or centenarians) affects preferentially the CD8+ subset of T cells. This decline accounts largely for the age-related diminution of T cell responsiveness to mitogenic signals. CD28 expression is modulated in T cell cultures in a growth-related fashion and this modulation is dampened in cultures from centenarians. We propose that the decrease in CD28 expression reflects a compensatory adaptation of the immune system during aging in the face of chronic stimulation.

Administration of an anti-CD8 monoclonal antibody interferes with the clearance of chimeric simian/human immunodeficiency virus during primary infections of rhesus macaques

Parenteral administration of a mouse anti-human CD8 monoclonal antibody (MAb) to rhesus macaques resulted in a transient depletion of CD8+ cells in both the peripheral blood and lymphoid tissues. When administered during primary chimeric simian/human immunodeficiency virus infections, the CD8 MAb caused marked elevations of plasma and cell-associated virus levels in both the peripheral blood and lymphoid tissues and led to prolonged depletion of CD4 cells. Taken together, these results directly demonstrate that CD8+ T lymphocytes are actively involved in controlling the acute phase of primate lentivirus infections.

Contribution of CD4+, CD8+CD28+, and CD8+CD28- T cells to CD3+ lymphocyte homeostasis during the natural course of HIV-1 infection

The relationship between the number of circulating CD4+ T cells and the presence of particular CD8+ T cell subsets was analyzed by flow cytometry on PBL from asymptomatic HIV-1-infected patients whose specimens were collected every 2 mo for a total period of 32 mo. Only slight variations were detected in the absolute number of lymphocytes and percentage of CD3+ lymphocytes, whereas both CD4+ and CD8+ T cell subsets showed wide intrapatient variation. Variations in the number of CD8+CD28+ cells paralleled those of the CD4+ T cell subset in each patient tested, while the presence of CD8+CD28- T cells correlated inversely with CD4+ and CD8+CD28+ T cells. These data show that changes in the number of circulating CD4+-and CD8+CD28+ T cells are strongly related to the presence of CD8+CD28- T cells in these patients. Insight into the significance of CD8+CD28- T cell expansion will allow us to understand the mechanisms and significance of the HIV-1- driven change in CD4+CD8+ T cell homeostasis and the basic immunopathology of HIV disease.

Interleukin-1 beta converting enzyme-like protease involvement in Fas-induced and activation-induced peripheral blood T cell apoptosis in HIV infection. TNF-related apoptosis-inducing ligand can mediate activation-induced T cell death in HIV infection

Apoptosis of peripheral blood T cells has been suggested to play an important role in the pathogenesis of human immunodeficiency virus (HIV) infection. Spontaneous, Fas (CD95)-induced and activation-induced T cell apoptosis have all been described in peripheral blood mononuclear cell cultures of HIV-infected individuals. We have previously shown that activation-induced T cell apoptosis is Fas independent in peripheral blood T cells from HIV+ individuals. In this study, we extend and confirm these observations by using an inhibitor of interleukin-1 beta converting enzyme (ICE) homologues. We show that z-VAD-fmk, a tripeptide inhibitor of ICE homologues, can inhibit Fas-induced apoptosis of peripheral blood CD4(+) and CD8+ T cells from asymptomatic HIV+ individuals. z-VAD-fmk also inhibited activation (anti-CD3)- induced CD4+ and CD8+ T cell apoptosis (AICD) in some but not all asymptomatic HIV+ individuals. Apoptosis was measured by multiparameter flow cytometry. The z-VAD-fmk inhibitor also enhanced survival of T cells in anti-Fas or anti-CD3 antibody-treated cultures and inhibited DNA fragmentation. AICD that could be inhibited by z-VAD-fmk was Fas independent and could be inhibited with a blocking monoclonal antibody to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), a recently described member of the TNF/nerve growth factor ligand family. The above findings show that Fas-induced T cell apoptosis is ICE dependent in HIV infection. AICD can be blocked by ICE inhibitors in some patients, and this AICD is mediated by TRAIL. These results show that TRAIL can be a mediator of AICD in T cells. These different mechanisms of peripheral blood T cell apoptosis may play different roles in the pathogenesis of HIV infection.

Direct ex vivo simian immunodeficiency virus (SIV)-specific cytotoxic activity detected from small intestine intraepithelial lymphocytes of SIV-infected macaques at an advanced stage of infection

Human immunodeficiency virus (HIV) induces a profound disorganization of the lymphoid tissues with marked abnormalities of the immune system at the terminal stage of infection. Since the digestive mucosal immune system is by far the largest lymphoid organ of the body, we attempted to evaluate its functional activity in advanced stages of simian immunodeficiency virus (SIV) infection in the SIV-macaque model of HIV infection. Two chronically intravenously SIV-infected macaques, including one at the AIDS stage, were studied. Intestinal intraepithelial lymphocytes (IEL) were isolated, analyzed, and compared to lymphocytes obtained from blood, spleen, and different lymph nodes: IEL were predominantly CD8+ T lymphocytes expressing the alphaE beta7 integrin and lacking the CD28 coactivatory molecule. A direct ex vivo SIV-specific cytotoxic activity was prominently found in the IEL of both macaques and was weaker or absent in the other sites. To our knowledge, this is the first report of SIV-specific cytotoxic activity from small intestine IEL in SIV-infected macaques. Considering the high similitude of the SIV-macaque model with the HIV infection in humans, these results may be highly important for the pathogenesis of HIV infection and more generally important for the characterization and function of digestive CD8+ IEL population.

Evolution and plasticity of CTL responses against HIV

Exceptionally potent cytotoxic T lymphocyte responses are generated after HIV invasion and probably control the primary infection as well as the asymptomatic phase of HIV infection. The chronic phase appears as a quasi-equilibrium between waves of new HIV variants and variant-specific CTLs, thus sustaining continuous CTL activation which eventually fails to eradicate HIV disease progression and the reascension of viral replication. Meanwhile, both the host and the virus develop various strategies either to stop or to evade this potentially deleterious permanent CTL activity. The transient effectiveness of CTLs opens perspectives for understanding disease progression generally as well as for immune therapeutic strategies.