TGF-β modulates the functionality of tumor-infiltrating CD8<Superscript>+</Superscript> T cells through effects on TCR signaling and Spred1 expression

This study demonstrates that CD8⁺ T cells in the tumor microenvironment display reduced functionality and hyporesponsiveness. TGF-β contributed markedly to the tumor-infiltrating CD8⁺ T cells’ (TILs) reduced functionality, which could be reversed using a small molecule TGF-β inhibitor. Upon T-cell receptor (TCR) activation, the activation of ITK and ERK kinases were reduced in CD8⁺ TILs, as compared to splenic CD8⁺ T cells: TGF-β inhibitor could reverse this phenomenon. This study demonstrates for the first time the association of the Spred-1 gene, an inhibitor of the Ras/MAPK pathway, with CD8⁺ TILs and TGF-β activity. Spred-1 was upregulated in CD8⁺ TILs and TGF-β enhanced the expression of Spred-1 in effector/memory CD8⁺ T cells and not in rested/memory CD8⁺ T cells. Based on these findings, this study supports the hypothesis that TGF-β mediates an inhibitory mechanism on CD8⁺ TILs involving TCR-signaling blockade and the upregulation of Spred-1, thus implicating Spred-1 as a potential new target for future anti-tumor immune studies. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. M. G. di Bari and M. E. C. Lutsiak contributed equally to this work.     

T-cell activation without proliferation in juvenile idiopathic arthritis

A study was done to determine if the differentiation and activation phenotype of T cells in synovial fluid (SF) from patients with juvenile idiopathic arthritis (JIA) is associated with T-cell proliferation in situ. Mononuclear cells were isolated from 44 paired samples of peripheral blood and SF. Differentiation and activation markers were determined on CD4 and CD8 T cells by flow cytometry. Cell-cycle analysis was performed by propidium iodide staining, and surface-marker expression was also assessed after culture of the T cells under conditions similar to those found in the synovial compartment. The majority of the T cells in the SF were CD45RO⁺CD45RB^dull. There was greater expression of the activation markers CD69, HLA-DR, CD25 and CD71 on T cells from SF than on those from peripheral blood. Actively dividing cells accounted for less than 1% of the total T-cell population in SF. The presence or absence of IL-16 in T-cell cultures with SF or in a hypoxic environment did not affect the expression of markers of T-cell activation. T cells from the SF of patients with JIA were highly differentiated and expressed early and late markers of activation with little evidence of in situ proliferation. This observation refines and extends previous reports of the SF T-cell phenotype in JIA and may have important implications for our understanding of chronic inflammation.     

Prognostic impact of B-cell density in cutaneous melanoma

Studies on the prognostic importance of tumor-infiltrating lymphocytes have mainly focused on T cells, while little is known about the role of tumor-infiltrating B lymphocytes. We investigated the prevalence of CD20⁺ B cells by immunohistochemistry in primary melanoma samples of 106 patients and analyzed in relation to clinicopathological parameters and patients’ survival. The majority of samples contained a significant amount of B lymphocytes, predominantly dispersed in the stroma surrounding tumor deposits (mean peritumoral and intratumoral densities: 178.7 ± 156.1 vs. 4.9 ± 6.9 cells/mm², respectively). B cells organized in follicle-like aggregates were also observed in 26% of the samples. B-cell density correlated with that of activated (CD25⁺ or OX40⁺) T lymphocytes. Infiltration by CD20⁺ lymphocytes did not correlate with tumor thickness, while the presence of B-cell aggregates was observed more frequently in thick melanomas. On the other hand, B-cell infiltration was more pronounced in nonmetastatic or lymph node metastatic tumors, compared to visceral metastatic ones. Accordingly, high number of these cells provided significant survival advantage (P = 0.0391 and P = 0.0136 for intra- and peritumoral infiltration, respectively). Furthermore, combination of peritumoral B-cell density with the number of activated T lymphocytes identified patient subgroups with different disease outcome, which was most favorable in the case of high density, while very poor in the case of low density of both cell types. Multivariate survival analysis identified tumor thickness and CD20⁺/OX40⁺ cell density combination as significant independent prognostic factors. Taken together, our results show correlation between low number of CD20⁺ B lymphocytes and melanoma progression, indicating a possible role of tumor-infiltrating B cells in antitumoral immune response. It was also reflected in better outcome of the disease since the density of B lymphocytes alone as well as in combination with that of activated T cells proved of prognostic importance in patients with malignant melanoma.     

Manganese is critical for antitumor immune responses via cGAS-STING and improves the efficacy of clinical immunotherapy

CD8⁺ T cell-mediated cancer clearance is often suppressed by the interaction between inhibitory molecules like PD-1 and PD-L1, an interaction acts like brakes to prevent T cell overreaction under normal conditions but is exploited by tumor cells to escape the immune surveillance. Immune checkpoint inhibitors have revolutionized cancer therapeutics by removing such brakes. Unfortunately, only a minority of cancer patients respond to immunotherapies presumably due to inadequate immunity. Antitumor immunity depends on the activation of the cGAS-STING pathway, as STING-deficient mice fail to stimulate tumor-infiltrating dendritic cells (DCs) to activate CD8⁺ T cells. STING agonists also enhance natural killer (NK) cells to mediate the clearance of CD8⁺ T cell-resistant tumors. Therefore STING agonists have been intensively sought after. We previously discovered that manganese (Mn) is indispensable for the host defense against cytosolic dsDNA by activating cGAS-STING. Here we report that Mn is also essential in innate immune sensing of tumors and enhances adaptive immune responses against tumors. Mn-insufficient mice had significantly enhanced tumor growth and metastasis, with greatly reduced tumor-infiltrating CD8⁺ T cells. Mechanically, Mn²⁺ promoted DC and macrophage maturation and tumor-specific antigen presentation, augmented CD8⁺ T cell differentiation, activation and NK cell activation, and increased memory CD8⁺ T cells. Combining Mn²⁺ with immune checkpoint inhibition synergistically boosted antitumor efficacies and reduced the anti-PD-1 antibody dosage required in mice. Importantly, a completed phase 1 clinical trial with the combined regimen of Mn²⁺ and anti-PD-1 antibody showed promising efficacy, exhibiting type I IFN induction, manageable safety and revived responses to immunotherapy in most patients with advanced metastatic solid tumors. We propose that this combination strategy warrants further clinical translation.Subject terms: Pattern recognition receptors, Immunosurveillance     

Decreased expression of interleukin-36α correlates with poor prognosis in hepatocellular carcinoma

Interleukin-36α (IL-36α) has been found to have a prominent role in the pathogenesis of inflammatory disorders; however, little is known about the role of IL-36α in cancer. In this study, we investigated the expression, prognostic value, and the underlying antitumor mechanism of IL-36α in hepatocellular carcinoma (HCC). From immunohistochemistry analysis, IL-36α expression was lower in poorly differentiated HCC cells. In clinicopathological analysis, low IL-36α expression significantly correlated with tumor size, histological differentiation, tumor stage, and vascular invasion, and low intratumoral IL-36α expression had significantly worse overall survival rates and shorter disease-free survival rates. Moreover, intratumoral IL-36α expression was an independent risk factor for overall survival. Consecutive sections were used to detect CD3⁺, CD8⁺, and CD4⁺ tumor-infiltrating lymphocytes (TILs), and we found that high-IL-36α-expressing tumor tissues exhibited a significantly higher proportion of intratumoral CD3⁺ and CD8⁺ TILs, but not CD4⁺ TILs. Our in vitro model confirmed that supernatant from IL-36α-overexpressing human HCC cells had an increased capacity to recruit CD3⁺ and CD8⁺ T cells. Consistently, mouse HCC cells engineered to overexpress IL-36α demonstrated markedly delayed growth in vivo, as well as higher levels of intratumoral CD3⁺ and CD8⁺ TILs, compared with control mice. In vitro chemotaxis analysis also showed that mouse HCC cells overexpressing IL-36α could recruit more number of CD3⁺ and CD8⁺ T cells. These results show that IL-36α expression may play a pivotal role in determining the prognosis of patients with HCC, which we attribute to the activation of adaptive T cell immunity, especially CD8⁺ T cell immune response.     

Stimulation of wnt/ß-catenin pathway in human CD8(+) T lymphocytes from blood and lung tumors leads to a shared young/memory phenotype

Cancer can be treated by adoptive cell transfer (ACT) of T lymphocytes. However, how to optimally raise human T cells to a differentiation state allowing the best persistence in ACT is a challenge. It is possible to differentiate mouse CD8⁺ T cells towards stem cell-like memory (T_SCM) phenotype upon TCR stimulation with Wnt/ß-catenin pathway activation. Here, we evaluated if T_SCM can be obtained from human mature CD8⁺ T cells following TCR and Wnt/ß-catenin activation through treatment with the chemical agent 4,6-disubstituted pyrrolopyrimidine (TWS119), which inhibits the glycogen synthase kinase-3β (GSK-3β), key inhibitor of the Wnt pathway. Human CD8⁺ T cells isolated from peripheral blood or tumor-infiltrating lymphocytes (TIL), and treated with TWS119 gave rise to CD62L⁺CD45RA⁺ cells, indicative of early differentiated stage, also expressing CD127 which is normally found on memory cells, and CD133, an hematopoietic stem cell marker. T_SCM cells raised from either TIL or blood secreted numerous inflammatory mediators, but in lower amounts than those measured without TWS119. Finally, generated T_SCM CD8⁺ T cells expressed elevated Bcl-2 and no detectable caspase-3 activity, suggesting increased persistence. Our data support a role for Wnt/ß-catenin pathway in promoting the T_SCM subset in human CD8⁺ T cells from TIL and the periphery, which are relevant for ACT.     

Co-Stimulation through 4-1BB/CD137 Improves the Expansion and Function of CD8+ Melanoma Tumor-Infiltrating Lymphocytes for Adoptive T-Cell Therapy

Adoptive T-cell therapy (ACT) using tumor-infiltrating lymphocytes (TIL) can induce tumor regression in up to 50% or more of patients with unresectable metastatic melanoma. However, current methods to expand melanoma TIL, especially the “rapid expansion protocol” (REP) were not designed to enhance the generation of optimal effector-memory CD8⁺ T cells for infusion. One approach to this problem is to manipulate specific co-stimulatory signaling pathways to enhance CD8⁺ effector-memory T-cell expansion. In this study, we determined the effects of activating the TNF-R family member 4-1BB/CD137, specifically induced in activated CD8⁺ T cells, on the yield, phenotype, and functional activity of expanded CD8⁺ T cells during the REP. We found that CD8⁺ TIL up-regulate 4-1BB expression early during the REP after initial TCR stimulation, but neither the PBMC feeder cells in the REP or the activated TIL expressed 4-1BB ligand. However, addition of an exogenous agonistic anti-4-1BB IgG₄ (BMS 663513) to the REP significantly enhanced the frequency and total yield of CD8⁺ T cells as well as their maintenance of CD28 and increased their anti-tumor CTL activity. Gene expression analysis found an increase in bcl-2 and survivin expression induced by 4-1BB that was associated with an enhanced survival capability of CD8⁺ post-REP TIL when re-cultured in the absence or presence of cytokines. Our findings suggest that adding an agonistic anti-4-1BB antibody during the time of TIL REP initiation produces a CD8⁺ T cell population capable of improved effector function and survival. This may greatly improve TIL persistence and anti-tumor activity in vivo after adoptive transfer into patients.     

Polyfunctional T cells accumulate in large human cytomegalovirus-specific T cell responses

Large cytomegalovirus (CMV)-specific CD8 T-cell responses are observed in both young and, somewhat more often, old people. Frequent CMV reactivation is thought to exhaust these cells and render them dysfunctional so that larger numbers of them are needed to control CMV. Expansions of CMV-specific CD4 T cells are also seen but are less well studied. In this study, we examined the T-cell response to the dominant CMV pp65 and IE-1 antigens in healthy CMV-infected people across a wide age range (20 to 84 years) by using multicolor flow cytometry. CMV-specific T cells were characterized by the activation markers CD40 ligand (CD40L), interleukin-2 (IL-2), tumor necrosis factor alpha (TNF-α), and gamma interferon (IFN-γ) and the memory markers CD27 and CD45RA. The proportions of effector memory T cells increased in large responses, as did the proportions of polyfunctional CD8 (IFN-γ⁺ IL-2^+/− TNF-α⁺) and CD4 (CD40L^+/− IFN-γ⁺ IL-2⁺ TNF-α⁺) T-cell subsets, while the proportion of naïve T cells decreased. The bigger the CD4 or CD8 T-cell response to pp65, the larger was the proportion of T cells with an advanced memory phenotype in the entire (including non-CMV-specific) T-cell compartment. In addition, the number of activation markers per cell correlated with the degree of T-cell receptor downregulation, suggesting increased antigen sensitivity in polyfunctional cells. In summary, our findings show that polyfunctional CMV-specific T cells were not superseded by dysfunctional cells, even in very large responses. At the same time, however, the memory subset composition of the entire T-cell compartment correlated with the size of the T-cell response to CMV pp65, confirming a strong effect of CMV infection on the immune systems of some, but not all, infected people.     

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.     

Increased intratumoral IL-22-producing CD4+ T cells and Th22 cells correlate with gastric cancer progression and predict poor patient survival

IL-22-producing CD4⁺ T cells (IL-22⁺CD4⁺ T cells) and Th22 cells (IL-22⁺IL-17^?IFN-γ^?CD4⁺ T cells) represent newly discovered T-cell subsets, but their nature, regulation, and clinical relevance in gastric cancer (GC) are presently unknown. In our study, the frequency of IL-22⁺CD4⁺ T cells in tumor tissues from 76 GC patients was significantly higher than that in tumor-draining lymph nodes, non-tumor, and peritumoral tissues. Most intratumoral IL-22⁺CD4⁺ T cells co-expressed IL-17 and IFN-γ and showed a memory phenotype. Locally enriched IL-22⁺CD4⁺ T cells positively correlated with increased CD14⁺ monocytes and IL-6 and IL-23 detection ex vivo, and in vitro IL-6 and IL-23 induced the polarization of IL-22⁺CD4⁺ T cells in a dose-dependent manner and the polarized IL-22⁺CD4⁺ T cells co-expressed of IL-17 and IFN-γ. Moreover, IL-22⁺CD4⁺ T-cell subsets (IL-22⁺IL-17⁺CD4⁺, IL-22⁺IL-17^?CD4⁺, IL-22⁺IFN-γ⁺CD4⁺, IL-22⁺IFN-γ^?CD4⁺, and IL-22⁺IL-17⁺IFN-γ⁺CD4⁺ T cells), and Th22 cells were also increased in tumors. Furthermore, higher intratumoral IL-22⁺CD4⁺ T-cell percentage and Th22-cell percentage were found in patients with tumor-node-metastasis stage advanced and predicted reduced overall survival. In conclusion, our data indicate that IL-22⁺CD4⁺ T cells and Th22 cells are likely important in establishing the tumor microenvironment for GC; increased intratumoral IL-22⁺CD4⁺ T cells and Th22 cells are associated with tumor progression and predict poorer patient survival, suggesting that tumor-infiltrating IL-22⁺CD4⁺ T cells and Th22 cells may be suitable therapeutic targets in patients with GC.     

Early Skewed Distribution of Total and HIV-Specific CD8+ T-Cell Memory Phenotypes during Primary HIV Infection Is Related to Reduced Antiviral Activity and Faster Disease Progression

The important role of the CD8⁺ T-cells on HIV control is well established. However, correlates of immune protection remain elusive. Although the importance of CD8⁺ T-cell specificity and functionality in virus control has been underscored, further unraveling the link between CD8⁺ T-cell differentiation and viral control is needed. Here, an immunophenotypic analysis (in terms of memory markers and Programmed cell death 1 (PD-1) expression) of the CD8⁺ T-cell subset found in primary HIV infection (PHI) was performed. The aim was to seek for associations with functional properties of the CD8⁺ T-cell subsets, viral control and subsequent disease progression. Also, results were compared with samples from Chronics and Elite Controllers. It was found that normal maturation of total and HIV-specific CD8⁺ T-cells into memory subsets is skewed in PHI, but not at the dramatic level observed in Chronics. Within the HIV-specific compartment, this alteration was evidenced by an accumulation of effector memory CD8⁺ T (T_EM) cells over fully differentiated terminal effector CD8⁺ T (T_TE) cells. Furthermore, higher proportions of total and HIV-specific CD8⁺ T_EM cells and higher HIV-specific T_EM/(T_EM+T_TE) ratio correlated with markers of faster progression. Analysis of PD-1 expression on total and HIV-specific CD8⁺ T-cells from PHI subjects revealed not only an association with disease progression but also with skewed memory CD8⁺ T-cell differentiation. Most notably, significant direct correlations were obtained between the functional capacity of CD8⁺ T-cells to inhibit viral replication in vitro with higher proportions of fully-differentiated HIV-specific CD8⁺ T_TE cells, both at baseline and at 12 months post-infection. Thus, a relationship between preservation of CD8⁺ T-cell differentiation pathway and cell functionality was established. This report presents evidence concerning the link among CD8⁺ T-cell function, phenotype and virus control, hence supporting the instauration of early interventions to prevent irreversible immune damage.     

The Polyunsaturated Fatty Acids Arachidonic Acid and Docosahexaenoic Acid Induce Mouse Dendritic Cells Maturation but Reduce T-Cell Responses In Vitro

Long-chain polyunsaturated fatty acids (PUFAs) might regulate T-cell activation and lineage commitment. Here, we measured the effects of omega-3 (n-3), n-6 and n-9 fatty acids on the interaction between dendritic cells (DCs) and naïve T cells. Spleen DCs from BALB/c mice were cultured in vitro with ovalbumin (OVA) with 50 μM fatty acids; α-linolenic acid, arachidonic acid (AA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), linoleic acid or oleic acid and thereafter OVA-specific DO11.10 T cells were added to the cultures. Fatty acids were taken up by the DCs, as shown by gas chromatography analysis. After culture with arachidonic acid or DHA CD11c⁺ CD11b⁺ and CD11c⁺ CD11b^neg DCs expressed more CD40, CD80, CD83, CD86 and PDL-1, while IA^d remained unchanged. However, fewer T cells co-cultured with these DCs proliferated (CellTrace Violet^low) and expressed CD69 or CD25, while more were necrotic (7AAD⁺). We noted an increased proportion of T cells with a regulatory T cell (Treg) phenotype, i.e., when gating on CD4⁺ FoxP3⁺ CTLA-4⁺, CD4⁺ FoxP3⁺ Helios⁺ or CD4⁺ FoxP3⁺ PD-1⁺, in co-cultures with arachidonic acid- or DHA-primed DCs relative to control cultures. The proportion of putative Tregs was inversely correlated to T-cell proliferation, indicating a suppressive function of these cells. With arachidonic acid DCs produced higher levels of prostaglandin E₂ while T cells produced lower amounts of IL-10 and IFNγ. In conclusion arachidonic acid and DHA induced up-regulation of activation markers on DCs. However arachidonic acid- and DHA-primed DCs reduced T-cell proliferation and increased the proportion of T cells expressing FoxP3, indicating that these fatty acids can promote induction of regulatory T cells.     

IL2RA+VSIG4+ tumor-associated macrophage is a key subpopulation of the immunosuppressive microenvironment in anaplastic thyroid cancer

Extensive infiltration of tumor-associated macrophages was correlated poor prognosis in anaplastic thyroid cancer (ATC). However, the heterogeneity and characteristics of the ATC-associated macrophages (ATAMs) in ATC remain far from clear. We combined single-cell RNA-sequencing analysis and gene expression microarray datasets to assess the molecular signature of ATAMs. Compared with normal thyroid-associated macrophages (NTAMs), 778 differentially expressed genes (DEGs) significantly changed in ATAMs compared with NTAMs. These DEGs were correlated with oxidative phosphorylation (M2 phenotype) and phagocytosis (M1 phenotype). Moreover, ATAMs highly expressed pro-tumor genes associated with angiogenesis, fibrosis, metalloprotease activity, and metastasis. Notably, we identified one ATC-specific subset, IL2RA⁺ VSIG4⁺ ATAMs, co-expressed M1 and M2 markers. The infiltration of IL2RA⁺ VSIG4⁺ ATAMs showed strong correlation with BRAF and RAS signaling, and its high infiltration was associated with favorable prognosis in thyroid-cancer patients. IL2RA⁺ VSIG4⁺ ATAMs were associated with increased tumor-infiltrating lymphocytes (B cells, CD8⁺ T cells, Tregs). IL2RA⁺ VSIG4⁺ ATAMs interacted with CD8⁺ T cells and Tregs through immune checkpoints (such as LGALS9_HAVCR2), cytokines (such as CXCL10_CXCR3), and receptors (such as CSF1R_CSF1), thereby forming an immunosuppressive microenvironment. Multiplex immunohistochemistry staining and coculture experiment confirmed that ATC cancer cells were able to induce the polarization of IL2RA⁺ VSIG4⁺ ATAMs. Besides, we identified several novel ATC-specific immune checkpoint genes including the immunosuppressive molecule VSIG4, LAIR1, and LILRB2. Expression of VSIG4 was also significantly correlated with tumor-infiltrating lymphocytes (B cells, CD8⁺ T cells, Tregs). In conclusion, our study revealed an ATC-specific ATAM subset with bifunctional phenotype, which provided a comprehensive insight to delineate the molecular characteristics of ATC-associated macrophages.     

LINC00152 mediates CD8+ T-cell infiltration in gastric cancer through binding to EZH2 and regulating the CXCL9, 10/CXCR3 axis

This study aimed to annotate the role of long intergenic non-coding RNA 152 (LINC00152) in CD8⁺ T cells mediated immune responses in gastric cancer (GC) and the underlying mechanism. LINC00152 expression levels were detected through RT-PCR. For tumor engraftment, HGC-27 cells that received LINC00152 shRNA, LINC00152 overexpression vectors, enhancer of zeste homolog 2 (EZH2) shRNA or combination transfection were injected into mice. Chromatin immunoprecipitation (ChIP) assay was used to explore the interaction between LINC00152, Cys-X-cys ligand 9 (CXCL9) and Cys-X-cys ligand 10 (CXCL10). Flow cytometry was adopted to measure the CD8⁺ T-cell infiltration in tumor issue. In this study, we found increased LINC00152 expression levels are positively associated with the poor prognosis of GC patients and negatively associated with the CD8 levels. ChIP assay verified that LINC00152 recruits EZH2 to the promoters of CXCL9 and CXCL10, thus the silencing of LINC00152 promoted the production of CXCL9 and CXCL10. Knockdown of LINC00152 suppressed tumor cells growth in vivo and in vitro, increased tumor-infiltrating CD8⁺ T cells numbers and promoted the expression of CXCL9, CXCL10 and C-X-C Motif Chemokine Receptor 3 (CXCR3) in xenograft tumors. While CD8⁺ T cell depletion reversed the tumor suppression effect of LINC00152 silence. Besides, the silencing of EZH2 partly inhibited the promotion effect LINC00152 on tumor growth. Our study indicated that LINC00152 inhibition suppressed the tumor progress may through promoting CD8⁺ T-cell infiltration.

     

Comparative kinetic analyses of gene profiles of naïve CD4+ and CD8+ T cells from young and old animals reveal novel age-related alterations

It is well established that immune responses are diminished in the old. However, we still do not have a clear understanding of what dictates the dysfunction of old T cells at the molecular level. Although microarray analysis has been used to compare young and old T cells, identifying hundreds of genes that are differentially expressed among these populations, it has been difficult to utilize this information to pinpoint which biological pathways truly affect the function of aged T cells. To better define differences between young and old naïve CD4⁺ and CD8⁺ T cells, microarray analysis was performed pre‐ and post‐TCR stimulation for 4, 12, 24 and 72 h. Our data indicate that many genes are differentially expressed in the old compared to the young at all five time points. These genes encode proteins involved in multiple cellular functions such as cell growth, cell cycle, cell death, inflammatory response, cell trafficking, etc. Additionally, the information from this microarray analysis allowed us to underline both intrinsic deficiencies and defects in signaling only seen after activation, such as pathways involving T‐cell signaling, cytokine production, and Th2 differentiation in old T cells. With the knowledge gained, we can proceed to design strategies to restore the function of old T cells. Therefore, this microarray analysis approach is a powerful and sensitive tool that reveals the extensive changes seen between young and old CD4⁺ and CD8⁺ naïve T cells. Evaluation of these differences provides in‐depth insight into potential functional and phenotypical differences among these populations.