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Matthew J Loza

Publications and source records attributed to Matthew J Loza.

14 recordsLinked to original sources
PubMed2006

beta-Agonist enhances type 2 T-cell survival and accumulation.

BACKGROUND: Neurohumoral modulation of immune system function is poorly understood. beta-Adrenergic receptor ligands (beta-agonists) subserve numerous physiologic processes but also function as pathogenic or therapeutic agents in numerous diseases with inflammatory components. OBJECTIVES: We sought to establish the effects of beta-agonists and prostaglandin E(2) (PGE(2)) on antigen-dependent and antigen-independent accumulation of IL-13(+) (type 2) and IFN-gamma(+) (type 1) T cells. We also sought to clarify the mechanisms mediating the effects of these G protein-coupled receptor agonists. METHODS: Effects of beta-agonists or PGE(2) on T-cell subtype accumulation were assessed in peripheral blood lymphocytes cultured with alphaCD3/CD28 or IL-2 by using flow cytometry. The role of cyclic AMP-dependent protein kinase (PKA) in mediating agonist effects was assessed by means of characterization of (1) phosphorylation of an intracellular PKA substrate and (2) T cells from patients with lupus possessing a natural defect in PKA activation. RESULTS: beta-Agonists, in contrast to PGE(2), increased IL-2-induced accumulation of human type 2 T cells, an effect attributable to differential activation of PKA affecting regulation of cell proliferation and apoptosis. In T cells from patients with lupus exhibiting defective PKA activation, both beta-agonists and PGE(2) promoted an increase in type 2 T-cell accumulation. CONCLUSION: G(s)-coupled receptors have the capacity to elicit prosurvival signaling in type 2 T cells, which, in most instances, is obscured by concomitant and antimitogenic PKA activation. CLINICAL IMPLICATIONS: beta-Agonists and other G(s)-coupled receptor agonists have the potential to regulate T-cell development to affect disease pathogenesis or the efficacy of therapies, and variability of effect relates to the ability to stimulate PKA activity.

Adrenergic beta-Agonists↗
PubMed2005

Beta-agonists modulate T-cell functions via direct actions on type 1 and type 2 cells.

Although the beta2-adrenergic receptor (beta2AR) is the most extensively characterized G-protein-coupled receptor (GPCR), the effects of beta-agonists on T-cell subtype function remain poorly understood. In contrast to studies suggesting lack of beta2AR expression on type 2 T cells, we demonstrate that type 2 interleukin-13+ (IL-13+) T cells (CD4+ or CD8+) in human peripheral blood lymphocytes (PBLs) can respond directly to beta-agonist, with effects including induction of protein kinase A (PKA) activity and associated inhibition of CD3-stimulated CD25 expression; CD3-stimulated IL-13, interferon-gamma (IFN-gamma), and IL-2 production; and p38 mitogen-activated protein kinase (MAPK) phosphorylation. PGE2 was more efficacious than beta-agonist in activating PKA and inhibiting cytokine production. beta-agonist and PGE2 also inhibited phorbol myristate acetate (PMA) + calcimycin-stimulated IFN-gamma and IL-2 (but not IL-13) production, suggesting that upstream CD3-initiated signaling is not the sole locus of PKA actions. Differential regulation of PMA-stimulated p38, p42/p44, and NF-kappaB explained the capacity of PGE2 and beta-agonist to inhibit IFN-gamma but not IL-13 production. The inhibition of CD3 + CD28-stimulated IL-13 production by both beta-agonist and PGE2 was reversed at low agonist concentrations, resulting in enhanced IL-13, but not IFN-gamma or IL-2, production. These findings identify direct effects of beta2AR activation on T-cell subtypes and suggest a complex role for GPCRs and PKA activity in modulating T-cell functions.

Adrenergic beta-2 Receptor Agonists↗
PubMed2005

Human peripheral CD2-/lo T cells: an extrathymic population of early differentiated, developing T cells.

We previously reported that a subset of human peripheral blood CD3+ T cells expresses low-to-null CD2 levels (CD2-/lo), produces type 2 cytokines and is inducible to differentiate to functionally mature IFN-gamma+ cells. Multiple-color immunofluorescence analysis indicated that this population, representing <0.1% of the T cells in fresh lymphocytes, contains subsets that are phenotypically immature, including CD4-CD8- and CD3+TCR- cells. Ex vivo, the CD2-/lo cells can proliferate (carboxyfluorescein diacetate succinimidyl ester analysis) independently from exogenous stimulation, respond to CD3-mediated stimulation with significantly greater proliferation than the autologous mature cells and their subsets are inducible to undergo in vitro a developmental sequence similar to that reported for the phenotypically similar thymic populations. This is especially evident for the CD4+CD8+ subset. CD2-/lo T-cell populations exhibit a TCR repertoire (Vbeta chain distribution) that is complete but different (complementarity determining region R3 analysis) from that of the autologous CD2+ T cells. These characteristics distinguish peripheral CD2-/lo T cells as possible early differentiated T cells that may undergo extrathymic maturation, and potentially contribute to maintain the peripheral naive T-cell pool. These findings define the existence of phenotypically immature T cells in the periphery. Also, given the high numbers of CD2-/lo T cells generated, upon ex vivo culture, from peripheral lymphocytes of all adult and neonatal individuals tested, they have relevance to clinical applications for immune reconstitution of T cells, as well as myeloid cells, via myeloid colony-stimulating factors and type 2 cytokines.

Adult↗
PubMed2005

Peripheral NK cell phenotypes: multiple changing of faces of an adapting, developing cell.

We have defined the existence of developmental relationships among human peripheral NK cells with distinct phenotypic and functional characteristics. These findings closely parallel the changes that occur in vivo during NK cell development, and in vitro in experimental culture systems supporting NK cell generation from hematopoietic progenitors. These new insights provide a simplified framework to understand NK cell immunobiology and the cellular bases for their roles in innate immunity, initiation and maintenance of immune responses via regulation of adaptive and accessory cell functions, and immune pathologies.

Antigens, CD↗
PubMed2004

The IL-12 signature: NK cell terminal CD56+high stage and effector functions.

We report that human peripheral NK cells expressing high CD56 levels (CD56(+high)) are terminally differentiated cells indistinguishable from mature NK cells recently activated in the presence of IL-12, and not a functionally distinct NK-cell subset or progenitors to mature CD56(+low) NK cells. CD56(+high) NK cells coexpress all differentiation Ags constitutive or inducible in mature (CD56(+)) NK cells, except CD16, present at lower level than on most mature NK cells. Also, activation markers, activating receptors and adhesion molecules, and most inducible receptors are expressed exclusively and constitutively and are inducible at higher levels on CD56(+high) than on CD56(+low) NK cells. Consistent with their activated phenotype, many CD56(+high) NK cells are cycling and mediate heightened effector functions (proliferation, IFN-gamma and IL-10 but not IL-13 production) in response to IL-12 and other NK cell-specific stimuli. Conversely, IL-12 induces on CD56(+low) NK cells all markers constitutively expressed on the CD56(+high) NK cells, concomitantly preventing the IL-2 (and IL-15)-inducible expression of NKp44 and CD16 re-expression after immune complex-induced down-modulation, and CD56(-/+low) NK cells acquire a CD56(+high) NK cell phenotype in short term in vitro culture with IL-12. The significance of these findings to the NK cell-mediated regulation of immune responses and NK cell development is discussed.

Adult↗
PubMed2004

Differential regulation of NK cell proliferation by type I and type II IFN.

IFN, produced during viral infections by accessory (type I IFN) or NK cells (type II IFN), play a primary role in the regulation of immune and anti-viral NK cell effector functions. Because IFN have anti-proliferative effects on several cell types, including hematopoietic cells, we asked whether they modulate proliferation of human NK cells, and whether IFN-alpha and IFN-gamma mediate distinct effects on NK cells at different developmental stages. Analysis of proliferation at the single-cell level in human NK cells indicated that both IFN types inhibit IL-4-induced accumulation of immature CD56(-) IL-13(+) NK cells in freshly separated peripheral blood lymphocytes and in cells derived from them after short-term cultures. However, IFN-gamma inhibited specifically the IL-4-dependent proliferation of these cells without affecting the IL-2-dependent one or that of the IL-13(-) cells, whereas IFN-alpha attenuated proliferation of NK cells at any developmental stage (both immature CD56(-)IL-13(+) and mature CD56(+)IL-13(-) IFN-gamma(+) NK cells) and contributed to their monokine-induced differentiation to IFN-gamma-producing cells. Adding to our previous report that IL-13 inhibits accumulation of mature IFN-gamma(+) NK cells, the present data unravel a mechanism by which peripheral immature IL-13(+) and mature IFN-gamma(+) NK cells can negatively regulate each other's accumulation.

Adult↗
PubMed2003

Accumulation of type 2 cytokine+ T cells: differentiation-independent proliferation of pre-existing type 2 T cells.

Analysis of proliferation and cytokine production at the single-cell level indicated that proliferation of pre-existing type 2 cytokine(+) human peripheral naive T cells (CD4(+) and CD8(+)) accounts for the accumulation of type 2 T cells in lymphocytes cultured with IL-2, with or without IL-4, and independently from TCR-mediated stimulation. This is because: firstly,the number of cells progenitor to the type 2 cytokine(+) T cells accumulated in culture is lower than that of the original cytokine(+) cells; secondly, percentages and numbers of the accumulated type 2 cytokine(+) T cells depend on those in the original lymphocyte population; thirdly, no accumulation occurs in cultures of lymphocytes experimentally depleted of type 2 cells; and fourthly, naive T cells do not require proliferation before producing type 2 cytokines. In contrast, accumulation of IFN-gamma(+) T cells in cultures with IL-12 can not be explained with induced proliferation of pre-existing IFN-gamma(+) cells, but depends on differentiation from more-immature cells. These novel insights into the regulation of type 2 and type 1 cytokine(+) T cells provide a new understanding of the cellular bases for the regulation of immune responses and for manipulating the immune system in clinical settings.

Cell Differentiation↗
PubMed2003

Multiple color immunofluorescence for cytokine detection at the single-cell level.

Detection of cytokines and identification of the producer cells are essential to define the interplay and the role of distinct leukocyte subsets in the development of immune and inflammatory responses. Several methods used to study cytokine expression are based on detection of the encoding mRNA (Northern blot, RNase protection assay, RT-PCR) or of protein in the supernatant from stimulated cells (ELISA, RIA, ELISPOT). These are simple and useful, but have limitations related to the need of using purified cell populations to precisely define the effector cells, and exception made for RT-PCR and ELISPOT assays, the requirement for relatively large numbers of cells for sufficient resolution. Here we present a method based on immunofluorescence (flow cytofluorimetry) to detect intracellular accumulation of cytokines in mixed leukocyte populations. It has the distinct advantage of: 1. identifying producing cells in mixed cell populations, 2. comparing quantitatively the levels of production within cells in a given population and among different cell subsets, and 3. defining simultaneous production of distinct cytokines by a single cell type. The detailed description/discussion of the method uses natural killer (NK) cells as an example, but this method can be applied to the study of other cell types, and is of special interest/use when analyzing subsets present in very low proportion.

Cells, Cultured↗
PubMed2002

Peripheral immature CD2-/low T cell development from type 2 to type 1 cytokine production.

Immature myeloid and NK cells exist, and undergo cytokine-induced differentiation, in the periphery. In this study, we show that also immature CD2(-/low) T cells exist in peripheral blood. These cells produce the type 2 cytokines IL-13, IL-4, and IL-5, but not IFN-gamma or IL-10, and, upon culture with IL-12- and TCR-mediated stimuli, differentiate to IL-13(+)IFN-gamma(+) cells producing high IL-2 levels, and finally IL-13(-)IFN-gamma(+) cells. The monokine combination IL-12, IL-18, and IFN-alpha substitutes for TCR-mediated stimulation to induce the same differentiation process in both immature CD2(-/low) and primary mature CD2(+) IL-13(+) T cells. IFN-alpha is needed to maintain high level IL-2 production, which is confined to type 2 cytokine-producing cells and lost in the IFN-gamma(+) ones. Upon TCR-mediated stimulation, IFN-gamma(+) cells are then induced to produce IL-10 as they undergo apoptosis. These data indicate that peripheral type 2 cytokine(+) T cells are immature cells that can differentiate to effector IFN-gamma(+) cells following a linear monokine-regulated pathway identical with that previously described for NK cells. They define the cellular bases to support that cell-mediated immune responses are regulated not only via Ag-induced activation of mature effector cells, but also via bystander monokine-induced maturation of immature T cells.

Adult↗
PubMed2002

Expression of type 1 (interferon gamma) and type 2 (interleukin-13, interleukin-5) cytokines at distinct stages of natural killer cell differentiation from progenitor cells.

To determine whether production of type 1 and type 2 cytokines defines discrete stages of natural killer (NK) cell differentiation, cytokine expression was analyzed in human NK cells generated in vitro in the presence of interleukin-15 (IL-15) and/or IL-2 from umbilical cord blood hematopoietic progenitors. Like peripheral NK cells, the CD161(+)/CD56(+) NK cells from these cultures contained a tumor necrosis factor alpha (TNF-alpha)(+)/granulocyte macrophage-colony-stimulating factor (GM-CSF)(+) subset, an interferon gamma (IFN-gamma)(+) subset, mostly included within the former, and very few IFN-gamma(-)/IL-13(+) cells. Instead, most immature CD161(+)/CD56(-) NK cells, detectable only in the cultures with IL-2, produced IL-13, TNF-alpha, and GM-CSF, but not IFN-gamma, and contained an IL-5(+) subset. In short-term cultures with IL-12 and feeder cells, a proportion of the immature cells acquired the ability to produce IFN-gamma. Part of these produced both IFN-gamma and IL-13, irrespective of induced CD56 expression. These in vitro data indicate that ability to produce the type 2 cytokines IL-13 and IL-5 defines CD161(+) NK cells at intermediate stages of differentiation, and is lost upon terminal functional differentiation, concomitant with acquired ability to produce IFN-gamma.

Cell Differentiation↗
PubMed2002

Distinction between IL-13+ and IFN-gamma+ natural killer cells and regulation of their pool size by IL-4.

The hypothesis that distinct subsets of NK cells produce type 2 and type 1 cytokines in resting naive lymphocytes was tested analyzing cytokine production at the single-cell level. Two non-overlapping IL-13+ and IFN-gamma+ subsets were identified in adult and neonatal NK cells. IL-2 maintained their relative proportion. Accumulation of the former was induced by IL-4, but not IL-13, and inhibited by IL-12; that of the latter was induced by IL-12 and inhibited by IL-4 and IL-13. IL-4 induced preferential proliferation of the pre-existing peripheral IL-13+ cells, whereas IL-12 had minimal effect on proliferation of the IFN-gamma+ NK cells. The IL-13+ cells (CD161+ only) are phenotypically distinct from the IFN-gamma+ ones (CD56+) before and after culture under any condition analyzed, and produce IL-13 in response to NK-sensitive target cells and PMA+Ca(2+) ionophore, whereas also FcgammaRIIIA and IL-2+IL-12 stimulate IFN-gamma production. These data define the existence and regulation of two distinct resting peripheral NK cell subsets producing type 1 and type 2 cytokines, and suggest possible roles for IL-13+ NK cells in allergy.

Adult↗
PubMed2002

NKT and T cells: coordinate regulation of NK-like phenotype and cytokine production.

A maturation-dependent change in phenotype and cytokine production from relatively immature CD161(-) or CD161(+), IL-13(+)IL-4(+), IFN-gamma(-), to mature CD161(+)CD56(+) IFN-gamma(+) cells occurs in primary human alpha-galactosyl ceramide-reactive CD1d-restricted natural killer T (NKT) cells under the control of IL-12 and other monokines. Modulation of this process upon alpha-galactosyl ceramide stimulation explains the opposite roles of NKT cells to drive type 1 and type 2 immune responses. Because the same developmental changes occurred and were similarly regulated in T cells, the data establish that NKT cells should no longer be considered a functionally unique regulatory subset. However, the results of their analysis can be taken as a model for immunotherapeutic approaches with T cells for which a nominal or surrogate antigen is defined.

Adult↗