Interleukin-2 promotes antigenic reactivity of rested T cells but prolongs the postactivational refractory phase of activated T cells

Soluble CD25 imposes a low-zone IL-2 signaling environment that favors competitive outgrowth of antigen-experienced CD25high regulatory and memory T cells

This study focused on soluble (s)CD25-mediated regulation of IL-2 signaling in murine and human CD4+ T cells. Recombinant sCD25 reversibly sequestered IL-2 to limit acute maximal proliferative responses while preserving IL-2 bioavailability to subsequently maintain low-zone IL-2 signaling during prolonged culture. By inhibiting IL-2 signaling during acute activation, sCD25 suppressed T-cell growth and inhibited IL-2-evoked transmembrane CD25 expression, thereby resulting in lower prevalence of CD25high T cells. By inhibiting IL-2 signaling during quiescent IL-2-mediated growth, sCD25 competed with transmembrane CD25, IL2Rβγ, and IL2Rαβγ receptors for limited pools of IL-2 such that sCD25 exhibited strong or weak inhibitory efficacy in IL-2-stimulated cultures of CD25low or CD25high T cells, respectively. Preferential blocking of IL-2 signaling in CD25low but not CD25high T cells caused competitive enrichment of CD25high memory/effector and regulatory FOXP3+ subsets. In conclusion, sCD25 modulates IL-2 bioavailability to limit CD25 expression during acute activation while enhancing CD25highT-cell dominance during low-zone homeostatic IL-2-mediated expansion, thereby 'flattening' the inflammatory curve over time.

Cytokine Networks in the Pathogenesis of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic systemic inflammation causing progressive joint damage that can lead to lifelong disability. The pathogenesis of RA involves a complex network of various cytokines and cells that trigger synovial cell proliferation and cause damage to both cartilage and bone. Involvement of the cytokines tumor necrosis factor (TNF)-α and interleukin (IL)-6 is central to the pathogenesis of RA, but recent research has revealed that other cytokines such as IL-7, IL-17, IL-21, IL-23, granulocyte macrophage colony-stimulating factor (GM-CSF), IL-1β, IL-18, IL-33, and IL-2 also play a role. Clarification of RA pathology has led to the development of therapeutic agents such as biological disease-modifying anti-rheumatic drugs (DMARDs) and Janus kinase (JAK) inhibitors, and further details of the immunological background to RA are emerging. This review covers existing knowledge regarding the roles of cytokines, related immune cells and the immune system in RA, manipulation of which may offer the potential for even safer and more effective treatments in the future.

Tolerogenic vaccines: Targeting the antigenic and cytokine niches of FOXP3+ regulatory T cells

FOXP3+ regulatory T cells (Tregs) constitute a critical barrier that enforces tolerance to both the self-peptidome and the extended-self peptidome to ensure tissue-specific resistance to autoimmune, allergic, and other inflammatory disorders. Here, we review intuitive models regarding how T cell antigen receptor (TCR) specificity and antigen recognition efficiency shape the Treg and conventional T cell (Tcon) repertoires to adaptively regulate T cell maintenance, tissue-residency, phenotypic stability, and immune function in peripheral tissues. Three zones of TCR recognition efficiency are considered, including Tcon recognition of specific low-efficiency self MHC-ligands, Treg recognition of intermediate-efficiency agonistic self MHC-ligands, and Tcon recognition of cross-reactive high-efficiency agonistic foreign MHC-ligands. These respective zones of TCR recognition efficiency are key to understanding how tissue-resident immune networks integrate the antigenic complexity of local environments to provide adaptive decisions setting the balance of suppressive and immunogenic responses. Importantly, deficiencies in the Treg repertoire appear to be an important cause of chronic inflammatory disease. Deficiencies may include global deficiencies in Treg numbers or function, subtle 'holes in the Treg repertoire' in tissue-resident Treg populations, or simply Treg insufficiencies that are unable to counter an overwhelming molecular mimicry stimulus. Tolerogenic vaccination and Treg-based immunotherapy are two therapeutic modalities meant to restore dominance of Treg networks to reverse chronic inflammatory disease. Studies of these therapeutic modalities in a preclinical setting have provided insight into the Treg niche, including the concept that intermediate-efficiency TCR signaling, high IFN-β concentrations, and low IL-2 concentrations favor Treg responses and active dominant mechanisms of immune tolerance. Overall, the purpose here is to assimilate new and established concepts regarding how cognate TCR specificity of the Treg repertoire and the contingent cytokine networks provide a foundation for understanding Treg suppressive strategy.

Deciphering the Finger Prints of Brain Cancer Glioblastoma Multiforme from Four Different Patients by Using Near Infrared Raman Spectroscopy

To explore the effectiveness of Raman spectra to diagnose brain cancer glioblastoma multiforme (GBM), we investigated the Raman spectra of single cell from four different GBM cell lines developed from four different patients and analyzed the spectra. The Raman spectra of brain cancer (GBM) cells were similar in all these cell lines. The results indicate that Raman spectra can offer the experimental basis for the cancer diagnosis and treatment.

IL-2 limits IL-12 enhanced lymphocyte proliferation during Leishmania amazonensis infection

C3H mice infected with Leishmania amazonensis develop persistent, localized lesions with high parasite loads. During infection, memory/effector CD44(hi)CD4(+) T cells proliferate and produce IL-2, but do not polarize to a known effector phenotype. Previous studies have demonstrated IL-12 is insufficient to skew these antigen-responsive T cells to a functional Th1 response. To determine the mechanism of this IL-12 unresponsiveness, we used an in vitro assay of repeated antigen activation. Memory/effector CD44(hi)CD4(+) T cells did not increase proliferation in response to either IL-2 or IL-12, although these cytokines upregulated CD25 expression. Neutralization of IL-2 enhanced CD4(+) T cell proliferation in response to IL-12. This cross-regulation of IL-12 responsiveness by IL-2 was confirmed in vivo by treatment with anti-IL-2 antibodies and IL-12 during antigen challenge of previously infected mice. These results suggest that during chronic infection with L. amazonensis, IL-2 plays a dominant, immunosuppressive role independent of identifiable conventional T(reg) cells.

Effect of DAB(389)IL-2 immunotoxin on the course of experimental autoimmune encephalomyelitis in Lewis rats

Activated T cells express the high affinity interleukin 2 receptor (IL-2R also CD25) that binds interleukin 2 (IL-2) and transduces signals important for the proliferation and survival of these cells. We investigated the effect of the genetically engineered immunotoxin DAB(389)IL-2 on experimental autoimmune encephalomyelitis (EAE), an autoimmune disease of the central nervous system (CNS) mediated by activated myelin-reactive T cells. EAE is the most commonly used animal model of the human disease multiple sclerosis (MS). DAB(389)IL-2 is a recombinant fusion product made of a portion of diphtheria toxin, which contains binding and translocation components of the toxin linked to IL-2. The diphtheria toxin targets and kills cells expressing the high affinity IL-2 receptor and has been successfully used in several autoimmune and neoplastic conditions. We observed a significant suppression of guinea-pig spinal cord homogenate (gpSCH)-MBP induced active EAE in Lewis rats at 2 x 1,600 kU of DAB(389)IL-2 given on days 7 and 9 post-immunization and complete suppression with the same dose on days 7, 8 and 9 or 7, 8, 9 and 10 after immunization during the active disease period. There were reduced mononuclear cell infiltrates of CD4(+), CD8(+), CD25(+) and alphabetaTCR(+) T cells in the spinal cord of treated rats. However, treatment at day 11 or 12 post-immunization led to severe, fatal disease. The toxin added to cultures in vitro or injected in vivo suppressed antigen- and mitogen-induced T cell proliferation. DAB(389)IL-2 treatment in vivo or exposure of encephalitogenic T cells in vitro prior to transfer did have a significant inhibitory effect on adoptive transfer EAE. Our data demonstrate that DAB(389)IL-2 immunotoxin can suppress active and passive EAE if applied at specific, early time points, but can have negative consequences at later time points.

Cytokine-neuroantigen fusion proteins: new tools for modulation of myelin basic protein (MBP)-specific T cell responses in experimental autoimmune encephalomyelitis

Fusion proteins incorporating anti-inflammatory cytokines and immunodominant self antigen as separate domains of a single protein may hold promise for development of antigen-specific tolerogenic vaccines. Proteins incorporating rat sequences of IL-1RA, IL-2, IL-4, IL-10, or IL-13 were expressed as fusion proteins containing the major encephalitogenic region of myelin basic protein (MBP). These fusion proteins were expressed via baculovirus (bv) expression systems and were shown to have cytokine-dependent and antigen-specific biological activity. In the case of the IL-2 and IL-4 fusion proteins, covalent linkage of the cytokine and neuroantigen domains resulted in synergistic antigen presentation. These data indicate that the cytokine domain may be able to modulate APC activity and simultaneously target the covalently tethered NAg for enhanced presentation by certain APC subsets. Cytokine/antigen fusion proteins may represent a novel tool for antigen-specific immune modulation in autoimmune disease.

Deciphering the finger Prints of Brain Cancer Astrocytoma in comparison to Astrocytes by using near infrared Raman Spectroscopy

To explore the biochemical differences between brain cancer cells Astrocytoma and normal cells Astrocyte, we investigated the Raman spectra of single cell from these two cell types and analyzed the difference in spectra and intensity. Raman spectrum shows the banding pattern of different compounds as detected by the laser. Raman intensity measures the intensity of these individual bands. The Raman spectra of brain cancer cells was similar to those of normal cells, but the Raman intensity of cancer cells was much higher than that of normal cells. The Raman spectra of brain cancer Astrocytoma shows that the structural changes of cancer cells happen so that many biological functions of these cells are lost. The results indicate that Raman spectra can offer the experimental basis for the cancer diagnosis and treatment.

Activation-dependent phases of T cells distinguished by use of optical tweezers and near infrared Raman spectroscopy

Near-infrared Raman spectroscopy may provide a highly sensitive, noninvasive means to identify activation status of leukocytes. The purpose of the current study was to establish Raman spectroscopic characteristics of T cell activation. Activation of the RsL.11 T cell clone in vitro with Con A resulted in specific decrements in band intensities at 785, 1048, 1093, and 1376 cm(-1) but did not alter a majority of other band intensities including those at 1004 cm(-1) (phenylalanine) and 1660 cm(-1) (amide bonds). Activation-dependent decrements in these band intensities occurred subsequent to IL-2 production and correlated closely with T cell blastogenesis. Activation-dependent decrements in these band intensities were not strictly a function of cell size because the same observations were noted in size-controlled comparisons of resting and activated T cells. Like the RsL.11 clone, freshly isolated thymocytes that were activated by Con A or IL-2 showed decrements in particular emissions. These findings indicate that near-infrared Raman spectroscopy can be used as a noninvasive technique to reveal the activation status of single living T cells.

IL-4 responsive CD4+ T cells specific for myelin basic protein: IL-2 confers a prolonged postactivation refractory phase

This study compared myelin basic protein-specific T cells from Lewis rats that were derived in the presence of either rat IL-4 or IL-2. Interleukin-4 was a maintenance factor that enabled derivation of long-term T cell lines. When activated, IL-4 dependent lines were lacking in IL-2 production capacity but maintained high levels of responsiveness to IL-2 and recognized IL-2 as a dominant growth factor. Activated IL-4 dependent T cells rapidly reverted to a quiescent phenotype in the presence of IL-4 and rapidly regained myelin basic protein reactivity. In contrast, activated IL-2 dependent T cells that were propagated in IL-2 had a more persistent blastogenic phenotype and a prolonged refractory phase. Interleukin-4 dependent lines that were propagated in IL-2 up-regulated the capacity to produce IL-2 and also acquired prolonged postactivation refractoriness. Thus, IL-2 was a dominant growth factor that conferred prolonged activation-dependent non-responsiveness. The coupling of dominant growth factor activity with prolonged postactivation refractoriness may be associated with the requisite role of IL-2 in homeostatic self-tolerance.

Food restriction and fish oil suppress atherogenic risk factors in lupus-prone (NZB x NZW) F1 mice

Atherosclerosis-mediated coronary artery disease is a significant cause of mortality in lupus patients. Both an activated immune system and hyperlipidemia are implicated in the pathogenesis of the atherosclerotic lesions of lupus. In this study, the increases in anticardiolipin antibodies, total cholesterol, and LDL cholesterol with age were significantly lowered by fish oil and food restriction, either alone or in combination. Food restriction also significantly decreased the elevation in anti-dsDNA antibody production seen with age in ad libitum groups. Interestingly, effects of food restriction and fish oil on both lipid profile and autoantibody production were seen from a young age. Accumulation of leukocytes in the blood vessels and deposition of IgG in the glomerular mesangium also were suppressed by food restriction. Thus, beneficial effects of fish oil and food restriction on lupus nephritis and survival could be, at least in part, due to their selective effect on atherogenic risk factors.

CD4+ and CD8+ mediated cellular immune response to recombinant influenza nucleoprotein

The stimulatory properties of soluble recombinant influenza nucleoprotein (NP) on purified CD4(+) and CD8(+) T cells from young and elderly individuals were studied. Recombinant influenza NP failed to induce proliferation of resting CD4(+) and CD8(+) T cells in the absence of IL-2. Addition of small amounts of IL-2, however, led to strong proliferation of resting CD4(+) and CD8(+) T cells from young and elderly donors. NP-reactive CD4(+) and CD8(+) T cell lines from both age groups grew equally well under long-term culture conditions. T cell lines raised to live influenza virus could recognize recombinant influenza NP and showed a substantial proliferative response. Stimulation of CD8(+) T cells is presumably due to cross-presentation, as EBV-transformed MHC class I-positive cell lines, which are incapable of antigen processing, stimulated live influenza virus-reactive CD8(+) T cell lines when loaded with NP-derived immunodominant peptides but not following loading with the whole NP molecule. Vaccines containing recombinant influenza NP might confer cross-protective immunity and could therefore be especially useful in cases of major epidemics or pandemics.

Serum interleukin 2 levels in patients with rheumatoid arthritis and correlation with insulin sensitivity

Interleukin 2 (IL-2), a Th1 lymphocyte-derived cytokine, is thought to play an important role in the pathogenesis of type 2 diabetes and rheumatoid arthritis (RA). The aim of our study was to evaluate changes in serum IL-2 levels and their correlation with glucose metabolism abnormalities, such as insulin resistance, in patients with RA. Thirty-six subjects with varying degrees of disease activity and 20 healthy age-, sex- and body mass index-matched control individuals were evaluated. Patients with any causes of peripheral insulin resistance were excluded. After a 12-h overnight fast, fasting insulin levels, homeostatic model assessment-insulin resistance (HOMA-IR) estimated insulin sensitivity, and serum IL-2 levels were significantly higher in all patients with RA than in the control individuals. Fasting insulin, HOMA-IR scores and IL-2 levels were correlated in the RA group. This study showed that patients with RA have altered IL-2 regulation, and that there was a significant correlation between serum IL-2 levels and insulin sensitivity.