Febrile temperature change modulates CD4 T cell differentiation via a TRPV channel-regulated Notch-dependent pathway.

Fever is a conserved and prominent response to infection. Yet, the issue of how CD4 T cell responses are modulated if they occur at fever temperatures remains poorly addressed. We have examined the priming of naive CD4 T cells in vitro at fever temperatures, and we report notable fever-mediated modulation of their cytokine commitment.

Functionally significant metabolic differences between B and T lymphocyte lineages.

Activation of B and T lymphocytes leads to major remodelling of the metabolic landscape of the cells enabling their post-activation functions. However, naive B and T lymphocytes also show metabolic differences, and the genesis, nature and functional significance of these differences are not yet well understood. Here we show that resting B-cells appeared to have lower energy demands than resting T-cells as they consumed lower levels of glucose and fatty acids and produced less ATP.

Correlation of cell-surface CD8 levels with function, phenotype and transcriptome of naive CD8 T cells.

We have previously demonstrated co-receptor level-associated functional heterogeneity in apparently homogeneous naive peripheral CD4 T cells, dependent on MHC-mediated tonic signals. Maturation pathways can differ between naive CD4 and naive CD8 cells, so we tested whether the latter showed similar co-receptor level-associated functional heterogeneity. We report that, when either polyclonal and T-cell receptor (TCR)-transgenic monoclonal peripheral naive CD8 T cells from young mice were separated into CD8 and CD8 subsets, CD8 cells responded poorly, but CD8 and CD8 subsets of CD8 single-positive (SP) thymocytes responded similarly.

Iloprost Affects Macrophage Activation and CCL2 Concentrations in a Microdialysis Model in Rats.

Purpose: The hypothesis that locally-released iloprost, a synthetic prostacyclin analog, affects macrophage phenotype at a microdialysis implant in the subcutaneous space of rats was tested. Macrophage activation towards alternatively-activated phenotypes using pharmaceutical release is of interest to improve integration of implants and direct the foreign body reaction toward a successful outcome.

Methods: Macrophage cell culture was used to test iloprost macrophage activation in vitro.

Effects of delayed delivery of dexamethasone-21-phosphate via subcutaneous microdialysis implants on macrophage activation in rats.

Macrophage activation is of interest in the biomaterials field since macrophages with an M(Dex) characteristic phenotype, i.e., CD68(+)CD163(+), are believed to result in improved integration of the biomaterial as well as improved tissue remodeling and increased biomaterial longevity.

Peripheral residence of naïve CD4 T cells induces MHC class II-dependent alterations in phenotype and function.

Background: As individual naïve CD4 T lymphocytes circulate in the body after emerging from the thymus, they are likely to have individually varying microenvironmental interactions even in the absence of stimulation via specific target recognition. It is not clear if these interactions result in alterations in their activation, survival and effector programming. Naïve CD4 T cells show unimodal distribution for many phenotypic properties, suggesting that the variation is caused by intrinsic stochasticity, although underlying variation due to subsets created by different histories of microenvironmental interactions remains possible.

Localized delivery of dexamethasone-21-phosphate via microdialysis implants in rat induces M(GC) macrophage polarization and alters CCL2 concentrations.

Microdialysis sampling probes were implanted into the subcutaneous space on the dorsal side of male Sprague Dawley rats to locally deliver dexamethasone-21-phosphate (Dex) with the aim of altering in vivo macrophage polarization. Macrophage polarization is of significant interest in the field of biomaterials since wound-healing macrophages are a possible means to extend implant life as well as improve tissue remodeling to an implant. Quantitative analysis of CCL2 in collected dialysates, gene expression and immunohistochemistry performed on the tissue surrounding the microdialysis implant were used to evaluate if Dex polarized macrophages.

T cell ageing: effects of age on development, survival & function.

Age associated decline of the immune system continues to be a major health concern. All components of innate and adaptive immunity are adversely affected to lesser or greater extent by ageing resulting in an overall decline of immunocompetence. As a result in the aged population, there is increased susceptibility to infection, poor responses to vaccination, and increased incidence of autoreactivity.

Role of apoptosis-inducing factor (Aif) in the T cell lineage.

Multiple checkpoints regulating finely balanced death-versus-survival decisions characterize both thymic development and peripheral homeostasis of T lymphocytes. While exploring the mechanisms of T cell death involved at various stages during the life of a T cell, we have observed and reported a variety of non-redundant roles for apoptosis inducing factor (Aif), a mitochondrial flavoprotein. Aif is ubiquitously expressed in all cell lineages and functions as an NADH oxidase in its mitochondrial location.

Comparison of microdialysis sampling perfusion fluid components on the foreign body reaction in rat subcutaneous tissue.

Microdialysis sampling is a commonly used technique for collecting solutes from the extracellular space of tissues in laboratory animals and humans. Large molecular weight solutes can be collected using high molecular weight cutoff (MWCO) membranes (100kDa or greater). High MWCO membranes require addition of high molecular weight dextrans or albumin to the perfusion fluid to prevent fluid loss via ultrafiltration.

A role for apoptosis-inducing factor in T cell development.

Apoptosis-inducing factor (Aif) is a mitochondrial flavoprotein that regulates cell metabolism and survival in many tissues. We report that aif-hypomorphic harlequin (Hq) mice show thymic hypocellularity and a cell-autonomous thymocyte developmental block associated with apoptosis at the β-selection stage, independent of T cell receptor β recombination. No abnormalities are observed in the B cell lineage.

Naive CD4 T cells from aged mice show enhanced death upon primary activation.

Poor T cell immunity is one of the many defects seen in elderly humans and aged (Ad) mice. We report that naive CD4 T cells from aged mice (ANCD4 cells) showed greater apoptosis upon primary activation than those from young (Yg) mice, with loss of mitochondrial membrane potential, poor activation of Rel family transcription factors and increased DNA damage. Their ability to enhance glycolysis, produce lactate and induce autophagy following activation was also compromised.

Increase in double-stranded DNA break-related foci in early-stage thymocytes of aged mice.

Cellular and molecular mechanisms involved in aging are notoriously complex. Aging-related immune decline of T lymphocyte function is partly caused by attrition of thymic T cell development, which involves programmed creation and repair of DNA breaks for generating T cell receptors. Aging also leads to significant alterations in the cellular DNA repair ability.

Gastrointestinal stromal tumors.

In the last 3 years 9 patients with gastrointestinal stromal tumors (GIST) underwent surgery at our department. All cases were with very atypical process. From these patients 3 interesting cases are described in more details.

Apoptosis-inducing factor regulates death in peripheral T cells.

Apoptosis-inducing factor (Aif) is a mitochondrial flavoprotein with multiple roles in apoptosis as well as in cellular respiration and redox regulation. The harlequin (Hq) mouse strain carries an aif locus modification causing reduced Aif expression. We demonstrate that activated CD4(+) and CD8(+) peripheral T cells from Hq mice show resistance to neglect-induced death (NID) triggered by growth factor withdrawal, but not to death induced by multiple agents that trigger DNA damage.

Inducible nitric oxide synthase in T cells regulates T cell death and immune memory.

The progeny of T lymphocytes responding to immunization mostly die rapidly, leaving a few long-lived survivors functioning as immune memory. Thus, control of this choice of death versus survival is critical for immune memory. There are indications that reactive radicals may be involved in this death pathway.

Somatic translocation and differential expression of Ig mu transgene copies implicate a role for the Igh locus in memory B cell development.

Memory B cells of mice with Ig mu transgenes often carry transgene copies that have moved into the Igh locus via somatic translocation. This phenomenon has been attributed to a selection pressure for somatic hypermutations, which generally are observed at much higher frequencies in translocated copies than in ectopic copies. We tested this idea by immunizing Ig-mu transgenic mice in a manner designed to select B cells that required only one V(H) mutation for a switch in antigenic specificity and recruitment into the memory pool.

Commitment of activated T cells to secondary responsiveness is enhanced by signals mediated by cAMP-dependent protein kinase A-I.

Modalities that induce specific differentiation to T cell memory in immune responses are important for vaccine design, but there is a paucity of well characterized molecular pathways useful to target for this purpose. We have shown previously that pentoxifylline (PF), a phosphodiesterase (PDE) inhibitor in common clinical use, enhances the commitment of in vitro allo-primed human T cells to secondary responsiveness, a characteristic crucial for memory T cells, which are key determinants of the longevity of the immune response. We now show that this effect can also be mediated by activation of adenylate cyclase (AC) and involves PDE4, but not PDE3 or PDE7.

Pentoxifylline functions as an adjuvant in vivo to enhance T cell immune responses by inhibiting activation-induced death.

Modalities for inducing long-lasting immune responses are essential components of vaccine design. Most currently available immunological adjuvants empirically used for this purpose cause some inflammation, limiting clinical acceptability. We show that pentoxifylline (PF), a phosphodiesterase (PDE) inhibitor in common clinical use, enhances long-term persistence of T cell responses, including protective responses to a bacterial immunogen, Salmonella typhimurium, via a cAMP-dependent protein kinase A-mediated effect on T cells if given to mice for a brief period during immunization.

Avian T helper one/two immune response balance can be shifted toward inflammation by antigen delivery to scavenger receptors.

Whether immune responses are dominated by inflammation or antibody production is often key to surviving infections. Therefore, differential control of these immune pathways determined by CD4 T cells is of fundamental interest for vaccine design. Little is known about how inflammatory [T helper cell (Th) type 1 (Th1)] versus antibody-inducing (Th2) choices are controlled in domestic fowl.

Induction of a germinal center phenotype in B cells in vitro by a Th2 cell line.

We have investigated the contribution of various stimuli for generating in vitro the changes in surface phenotype characteristic of B cells responding to a T-dependent antigen in a germinal center (GC). We show that, unlike many other stimuli such as B cell mitogens, cytokines, and surrogate antigen, alone or in combination, an alloreactive Th2 clonal line induces splenic B cells to become cell surface peanut agglutinin (PNA)(hi), Ig(lo), CD62L(lo), and CD44(hi) to produce mRNA for M17 and to express a GC-specific transgene even without B cell receptor ligation. Neither proliferation nor prior activation of responding B cells is needed, but B cells from CD45-null mice show reduced efficiency of this induction.

Expression of an immunoglobulin heavy chain transgene in macrophage as well as lymphocyte lineages in vivo.

A rearranged immunoglobulin heavy chain (IgH) transgene-encoded protein is expressed in macrophage lineage cells, in addition to B and T lineages, in transgenic mouse bone marrow. Peripheral macrophages also express transgenic IgH protein. Mature T cells express lower levels than immature thymocytes.

Presence of pentoxifylline during T cell priming increases clonal frequencies in secondary proliferative responses and inhibits apoptosis.

Naive T cells appear to be primed by specific Ag to differentiate into either effectors or memory cells. We have been analyzing the factors involved in this differential commitment in the priming of alloresponsive human T cells in vitro and have shown that the presence of a phosphodiesterase inhibitor, pentoxifylline (POX), during priming results in a decrease in the primary response and enhancement in the secondary proliferative response. We now show that the POX-mediated effect can be mimicked by dibutyryl cAMP.

Deletion of a recombined Ig heavy chain transgene in B-lineage cells of transgenic mice.

Fully recombined transgenes are stable in their transmission in the germline of transgenic mice, in common with the endogenous genetic complement of most mammalian somatic tissues, including the genes for lymphoid Ag receptors somatically generated from germline minigenes. There have, however, been isolated reports of unusual low frequency transgene losses in various transgenic mice. Here we show, using Southern blots and PCR-based assays, that plasmablast hybridomas and B cells from three independently derived founder lines of transgenic mice bearing a recombined heavy chain Ig transgene we have been studying show a significant net loss of transgene copies.

Presence of activated antigen-binding B cells during immunization enhances relative levels of IFN-gamma in T cell responses.

To examine the influence of Ag presentation by B cells on immune responses, we have used mice transgenic for an Ig heavy chain from a monoclonal anti-azobenzenearsonate (Ars) Ab to deliver Ag to B cells during immunization. A large proportion of transgene-expressing B cells in these mice binds Ars, while transgenic serum Ig shows poor Ars binding. Transgenic B cells present Ars proteins better than their nonhaptenated counterparts.