In vitro IL-15-activated human naïve CD8+ T cells down-modulate the CD8ß chain and become CD8αα T cells.

Antigen-driven human effector-memory CD8+ T cells expressing low levels of the CD8ß chain have been previously described. However, little is known on a possible antigen-independent trigger. We have examined the impact that IL-15 has on the expression of CD8ß on purified human naïve CD8+ T cells after CFSE labeling and culture with IL-15. As expected, IL-15 induced naïve CD8+ T cells to proliferate and differentiate. Remarkably, the process was associated with a cell-cycle dependent down-modulation of CD8ß from the cell surface, leading to the generation of CD8αßlow and CD8αß- (i.e., CD8αα) T cells. In contrast, expression of the CD8α chain remained steady or even increased. Neither IL-2 nor IL-7 reproduced the effect of IL-15. Determination of mRNA levels for CD8α and CD8ß isoforms by qPCR revealed that IL-15 promoted a significant decrease in mRNA levels of the CD8ß M-4 isoform, while levels of the M-1/M-2 isoforms and of CD8α increased. Noteworthy, CD8+ T cell blasts obtained after culture of CD8+ T cells with IL-15 showed a cell-cycle dependent increase in the level of the tyrosine kinase Lck, when compared to CD8+ T cells at day 0. This study has shown for the first time that IL-15 generates CD8αα+αßlow and CD8αα+αß- T cells containing high levels of Lck, suggesting that they may be endowed with unique functional features.

A Novel Bionebulizer Approach to Study the Effects of Natural Mineral Water on a 3D In Vitro Nasal Model from Allergic Rhinitis Patients.

Sulfurous thermal waters (STWs) are used as a complementary treatment for allergic rhinitis. However, there is scant data on the effects of STW on nasal epithelial cells, and in vitro models are warranted. The main aim of this study was to evaluate the dose and time effects of exposure to 3D nasal inserts (MucilAirTM-HF allergic rhinitis model) with STW or isotonic sodium chloride solution (ISCS) aerosols. Transepithelial electrical resistance (TEER) and histology were assessed before and after nebulizations. Chemokine/cytokine levels in the basal supernatants were assessed by enzyme-linked immunosorbent assay. The results showed that more than four daily nebulizations of four or more minutes compromised the normal epithelial integrity. In contrast, 1 or 2 min of STW or ISCS nebulizations had no toxic effect up to 3 days. No statistically significant changes in release of inflammatory chemokines MCP-1/CCL2 > IL-8/CXCL8 > MIP-1α/CCL3, no meaningful release of "alarmins" (IL-1α, IL-33), nor of anti-inflammatory IL-10 cytokine were observed. We have characterized safe time and dose conditions for aerosol nebulizations using a novel in vitro 3D nasal epithelium model of allergic rhinitis patients. This may be a suitable in vitro setup to mimic in vivo treatments of chronic rhinitis with STW upon triggering an inflammatory stimulus in the future.

HLA-A23/HLA-A24 serotypes and dementia interaction in the elderly: Association with increased soluble HLA class I molecules in plasma.

MHC class I molecules regulate brain development and plasticity in mice and HLA class I molecules are associated with brain disorders in humans. We investigated the relationship between plasma-derived soluble human HLA class I molecules (sHLA class I), HLA class I serotypes and dementia. A cohort of HLA class I serotyped elderly subjects with no dementia/pre-dementia (NpD, n = 28), or with dementia (D, n = 28) was studied. Multivariate analysis was used to examine the influence of dementia and HLA class I serotype on sHLA class I levels, and to compare sHLA class I within four groups according to the presence or absence of HLA-A23/A24 and dementia. HLA-A23/A24 and dementia, but not age, significantly influenced the level of sHLA class I. Importantly, the concurrent presence of HLA-A23/A24 and dementia was associated with higher levels of sHLA class I (p < 0.001). This study has shown that the simultaneous presence of HLA-A23/HLA-A24 and dementia is associated with high levels of serum sHLA class I molecules. Thus, sHLA class I could be considered a biomarker of neurodegeneration in certain HLA class I carriers.

Circadian rhythmicity of amyloid-beta-related molecules is disrupted in the choroid plexus of a female Alzheimer's disease mouse model.

The choroid plexus (CP) is part of the blood-cerebrospinal fluid barrier (BCSFB) and was recently described as an important component of the circadian clock system. It is the principal source of cerebrospinal fluid (CSF) and responsible for the synthesis and secretion of various neuroprotective peptides including those involved in amyloid-ß (Aß) transport/degradation, contributing to Aß homeostasis. Inadequate Aß metabolic clearance and transport across the BCSFB have been associated with circadian dysfunctions in Alzheimer's disease (AD) patients. To investigate whether AD pathology influences Aß scavengers circadian expression, we collected CP at different time points from an AD mouse model (APP/PS1) (female and male animals, aged 6- and 12-months-old) and analyzed their mRNA expression by Real-time RT-PCR. Only angiotensin-converting enzyme (Ace) expression in 6-month-old female wild-type mice and transthyretin (Ttr) expression in 12-month-old female wild-type mice presented significant rhythmicity. The circadian rhythmicity of Ace and Ttr, prompt us to analyze the involvement of circadian rhythm in Aß uptake. A human CP papilloma (HIBCPP) cell line was incubated with Aß-488 and uptake was evaluated at different time points using flow cytometry. Aß uptake displayed circadian rhythmicity. Our results suggest that AD might affect Aß scavengers rhythmicity and that Aß clearance is a rhythmic process possibly regulated by the rhythmic expression of Aß scavengers.

Antibodies to cryptic epitopes on HLA class I and class II heavy chains bound to single antigen beads: Clinically relevant?

Cell surface HLA class I consists of trimers, i.e., alpha - heavy chain, beta - 2 - microglobulin, and a peptide, termed closed conformers (CC) on non-activated lymphocytes. HLA class I and class II may also exist, respectively, as alpha-chain only or alpha and beta - chain only on activated cells termed open conformers (OC). We extend previous studies using an OC-specific monoclonal antibody that demonstrate LABScreen HLA class I and II single antigen beads (SABs) contain a mixture of open and closed conformers. LIFECODES SABs have bound CC only. More HLA class I and class II LABScreen SABs were reactive than LIFECODES SABs due to the presence of OC on LABScreen SABs. We hypothesized that antibody against OC on HLA B antigens would not be detected in cell based cross matches (XMs) with typical lymphocyte targets since anti-HLA OC antibodies would not react with native HLA CC on the cell surface. To test this hypothesis, we performed flow cytometry XM (FCXM) assays with sera of sufficient strength that most laboratories would likely predict positive FCXMs. Sera that reacted strongly with LABScreen SABs (>13,000 MFI) but weakly or not at all with LIFECODES SABs (<1000 MFI) gave negative T and B cell FCXMs. In contrast, sera that reacted with LIFECODES SABs (>13,000 MFI) but weakly with LABScreen SABs (<2100 MFI) exhibited positive FCXMs. Detection of antibodies directed against OC in SAB assays, may lead to inappropriate listing of unacceptable antigens, a decision not to XM or pre-or post - transplant desensitization procedures.

Open MHC Class I Conformers: A Look through the Looking Glass.

Studies carried out during the last few decades have consistently shown that cell surface MHC class I (MHC-I) molecules are endowed with functions unrelated with antigen presentation. These include cis-trans-interactions with inhibitory and activating KIR and LILR, and cis-interactions with receptors for hormones, growth factors, cytokines, and neurotransmitters. The mounting body of evidence indicates that these non-immunological MHC-I functions impact clinical and biomedical settings, including autoimmune responses, tumor escape, transplantation, and neuronal development. Notably, most of these functions appear to rely on the presence in hematopoietic and non-hematopoietic cells of heavy chains not associated with ß2m and the peptide at the plasma membrane; these are known as open MHC-I conformers. Nowadays, open conformers are viewed as functional cis-trans structures capable of establishing physical associations with themselves, with other surface receptors, and being shed into the extracellular milieu. We review past and recent developments, strengthening the view that open conformers are multifunctional structures capable of fine-tuning cell signaling, growth, differentiation, and cell communication.

The Choroid Plexus Is an Alternative Source of Prolactin to the Rat Brain.

Among the more than 300 functions attributed to prolactin (PRL), this hormone has been associated with the induction of neurogenesis and differentiation of olfactory neurons especially during pregnancy, which are essential for maternal behavior. Despite the original hypothesis that PRL enters the central nervous system through a process mediated by PRL receptors (PRLR) at the choroid plexus (CP), recent data suggested that PRL transport into the brain is independent of its receptors. Based on transcriptomic data suggesting that PRL could be expressed in the CP, this work aimed to confirm PRL synthesis and secretion by CP epithelial cells (CPEC). The secretion of PRL and the distribution of PRLR in CPEC were further characterized using an in vitro model of the rat blood-cerebrospinal fluid barrier. RT-PCR analysis of PRL transcripts showed its presence in pregnant rat CP, in CPEC, and in the rat immortalized CP cell line, Z310. These observations were reinforced by immunocytochemistry staining of PRL in CPEC and Z310 cell cytoplasm. A 63-kDa immunoreactive PRL protein was detected by Western blot in CP protein extracts as well as in culture medium incubated with rat pituitary and samples of rat cerebrospinal fluid and serum. Positive immunocytochemistry staining of PRLR was present throughout the CPEC cytoplasm and in the apical and basal membrane of these cells. Altogether, our evidences suggest that CP is an alternative source of PRL to the brain, which might impact neurogenesis of olfactory neurons at the subventricular zone, given its proximity to the CP.

CD45RA, CD8ß, and IFNγ Are Potential Immune Biomarkers of Human Cognitive Function.

There is increasing evidence that in humans the adaptive immunological system can influence cognitive functions of the brain. We have undertaken a comprehensive immunological analysis of lymphocyte and monocyte populations as well as of HLA molecules expression in a cohort of elderly volunteers (age range, 64-101) differing in their cognitive status. Hereby, we report on the identification of a novel signature in cognitively impaired elderly characterized by: (1) elevated percentages of CD8+ T effector-memory cells expressing high levels of the CD45RA phosphate receptor (Temra hi); (2) high percentages of CD8+ T cells expressing high levels of the CD8ß chain (CD8ßhi); (3) augmented production of IFNγ by in vitro activated CD4+ T cells. Noteworthy, CD3+CD8+ Temra hi and CD3+CD8ßhi cells were associated with impaired cognition. Cytomegalovirus seroprevalence showed that all volunteers studied but one were CMV positive. Finally, we show that some of these phenotypic and functional features are associated with an increased frequency of the HLA-B8 serotype, which belongs to the ancestral haplotype HLA-A1, Cw7, B8, DR3, DQ2, among cognitively impaired volunteers. To our knowledge, this is the first proof in humans linking the amount of cell surface CD45RA and CD8ß chain expressed by CD8+ Temra cells, and the amount of IFNγ produced by in vitro activated CD4+ T cells, with impaired cognitive function in the elderly.

Biological Effects of Thermal Water-Associated Hydrogen Sulfide on Human Airways and Associated Immune Cells: Implications for Respiratory Diseases.

Natural mineral (thermal) waters have been used for centuries as treatment for various diseases. However, the scientific background of such therapeutic action is mostly empiric and based on knowledge acquired over time. Among the various types of natural mineral waters, sulfurous thermal waters (STWs) are the most common type in the center of Portugal. STWs are characterized by high pH, poor mineralization, and the presence of several ions and salts, such as bicarbonate, sodium, fluoride, silica, and carbonate. Furthermore, these waters are indicated as a good option for the treatment of various illnesses, namely respiratory diseases (e.g., allergic rhinitis, asthma, and chronic obstructive pulmonary disease). From the sulfide species present in these waters, hydrogen sulfide (H2S) stands out due to its abundance. In healthy conditions, H2S-related enzymes (e.g., cystathionine ß-synthase and cystathionine γ-lyase) are expressed in human lungs, where they have mucolytic, antioxidant, anti-inflammatory, and antibacterial roles, thus contributing to airway epithelium homeostasis. These roles occur mainly through S-sulfhydration, a post-translational modification through which H2S is able to change the activity of several targets, such as ion channels, second messengers, proteins, among others. However, in respiratory diseases the metabolism of H2S is altered, which seems to contribute somehow to the respiratory deterioration. Moreover, H2S has been regarded as a good biomarker of airway dysfunction and severity, and can be measured in serum, sputum, and exhaled air. Hence, in this review we will recapitulate the effects of STWs on lung epithelial-immune crosstalk through the action of its main component, H2S.

Distinctive CD8+ T cell and MHC class I signatures in polycythemia vera patients.

Polycythemia vera (PV) is a myeloproliferative neoplasm characterized by overproduction of red blood cells. We have performed a comprehensive characterization of blood immune cells for expression of naïve and memory receptors as well as ß2m-associated and ß2m-free MHC class I heavy chains, also known as closed and open conformers, respectively, in PV patients and age-matched controls (CTR). We show that the peripheral CD3+CD8+ T cell pool in PV patients is clearly divided into two discrete populations, a more granular CD3+CD8high T cell population enriched in effector-memory CD45RA+ T cells (CD8+ TEMRA) when compared to CTR (P < 0.001), and a less granular CD3+CD8int T cell population that is completely absent in the CTR group (78 vs. 0%, P < 0.001) and is a mixture of naïve (CD8+ TN) and CD8+ TEMRA cells expressing intermediate levels of CD28, i.e., CD3+CD8intCD28int. While the percentage of CD3+CD8int TN cells correlated positively with the number of erythrocytes, the percentage of CD3+CD8int TEMRA correlated negatively with the number of platelets. Finally, we report that PV patients' lymphocytes and monocytes display lower levels of closed (W6/32+) MHC-I conformers at the cell surface while exhibiting increased amounts of open (HC-10+) MHC-I conformers. The implications of this distinctive immune signature are discussed.

Divide, Conquer, and Sense: CD8+CD28- T Cells in Perspective.

Understanding the rationale for the generation of a pool of highly differentiated effector memory CD8+ T cells displaying a weakened capacity to scrutinize for peptides complexed with major histocompatibility class I molecules via their T cell receptor, lacking the "signal 2" CD28 receptor, and yet expressing a highly diverse array of innate receptors, from natural killer receptors, interleukin receptors, and damage-associated molecular pattern receptors, among others, is one of the most challenging issues in contemporary human immunology. The prevalence of these differentiated CD8+ T cells, also known as CD8+CD28-, CD8+KIR+, NK-like CD8+ T cells, or innate CD8+ T cells, in non-lymphoid organs and tissues, in peripheral blood of healthy elderly, namely centenarians, but also in stressful and chronic inflammatory conditions suggests that they are not merely end-of-the-line dysfunctional cells. These experienced CD8+ T cells are highly diverse and capable of sensing a variety of TCR-independent signals, which enables them to respond and fine-tune tissue homeostasis.

Clinical improvement following therapy for periodontitis: Association with a decrease in IL-1 and IL-6.

Although a number of inflammatory cytokines have been shown to be associated with periodontal pathogenesis, it is important to investigate further whether these biomarkers are associated with the degree of success in nonsurgical treatment of chronic periodontitis. The aim of the present study was to quantify the total levels of interleukin (IL)-1α, -1ß, -6, -10 and tumour necrosis factor (TNF)-α in gingival crevicular fluid (GCF) of chronic periodontitis patients prior to and following nonsurgical periodontal therapy. In total, 52 GCF samples from disease sites of patients with chronic periodontitis, prior to and following periodontal therapy, and ten non-disease sites from non-periodontitis subjects, were collected and cytokine concentrations were determined using a multiplex method. Periodontal parameters, including bleeding on probing, probing pocket depth and the clinical attachment level, in all the sites were recorded. Untreated disease sites exhibited higher cytokine levels in the GCF when compared with the non-disease sites. Nonsurgical periodontal therapy resulted in a statistically significant decrease in the total levels of IL-1α, -1ß and -6 in the GCF, but not in IL-10 or TNF-α. The results support the hypothesis that proinflammatory cytokines, including IL-1α, IL-1ß and IL-6, are likely to be involved in the pathogenesis of periodontitis and are good markers to evaluate the success of nonsurgical therapy in disease sites of patients with periodontitis.

IL-15 induces CD8+ T cells to acquire functional NK receptors capable of modulating cytotoxicity and cytokine secretion.

During the last years several authors have described a small population of CD8+ T cells expressing NK receptors (NKRs). Although their origin remains largely unknown, we have recently demonstrated that IL-15 is capable of inducing NKR expression in purified human CD8+CD56- T cells. In this study we show that IL-15-driven NKR induction in CD8+ T cells was linked with CD56 de novo acquisition, consistent with an effector-memory phenotype, increased anti-apoptotic levels, high granzyme B/perforin expression and with the ability of displaying in vitro NK-like cytotoxicity. Interestingly, dissection of NKR functional outcome in IL-15-cultured CD8+ T cells revealed: (i) that NKG2D cross-linking was able per se to upregulate degranulation levels and (ii) that KIR and NKG2A cross-linking upregulated secretion of cytokines such as IFN-γ, TNF-α, IL-1ß and IL-10. These results suggest that IL-15 is capable of differentiating CD8+ T cells into NK-like T cells displaying a regulatory phenotype.

Red blood cells release factors with growth and survival bioactivities for normal and leukemic T cells.

Human red blood cells are emerging as a cell type capable to regulate biological processes of neighboring cells. Hereby, we show that human red blood cell conditioned media contains bioactive factors that favor proliferation of normal activated T cells and leukemic Jurkat T cells, and therefore called erythrocyte-derived growth and survival factors. Flow cytometry and electron microscopy in parallel with bioactivity assays revealed that the erythrocyte factors are present in the vesicle-free supernatant, which contains up to 20 different proteins. The erythrocyte factors are thermosensitive and do not contain lipids. Native polyacrylamide gel electrophoresis followed by passive elution and mass spectrometry identification reduced the potential erythrocyte factors to hemoglobin and peroxiredoxin II. Two-dimensional differential gel electrophoresis of the erythrocyte factors revealed the presence of multiple hemoglobin oxy-deoxy states and peroxiredoxin II isoforms differing in their isoelectric point akin to the presence of ß-globin chains. Our results show that red blood cells release protein factors with the capacity to sustain T-cell growth and survival. These factors may have an unforeseen role in sustaining malignant cell growth and survival in vivo.

Uncoupling between CD1d upregulation induced by retinoic acid and conduritol-B-epoxide and iNKT cell responsiveness.

Gaucher disease (GD) is associated with upregulation of CD1d and MHC-class II expression by monocytes. While the physiological impact of CD1d upregulation remains uncertain, it has been proposed that MHC-class II upregulation is associated with inflammation. Hereby, we show that the decrease in MHC-class II expression seen in GD patients under therapy correlates positively with chitotriosidase activity, a marker of inflamed macrophages. We also show that retinoic acid (RA) and the beta-glucocerebrosidase inhibitor conduritol-B-epoxide (CBE) lead to upregulation of CD1d expression by THP-1 cells, which correlated with an increase in mRNA expression. In vitro co-culture experiments showed that RA treated THP-1 cells were more stimulatory for CD4(+) than for CD8(+) T cells, as determined by CFSE loss, in comparison to untreated THP-1 cells. Interestingly, even though addition of exogenous isoglobotrihexosylceramide (iGb3), a physiological CD1d ligand, augmented the percentage of dividing CD4(+) T cells, we could not detect a significant expansion of CD4(+)Valpha24(+) invariant Natural Killer T (iNKT) cells. In contrast, addition of alpha-galactosylceramide (alpha-GC) induced expansion of Valpha24(+) iNKT cells as determined by using alpha-GC-loaded human CD1d dimers. These results strengthen the existence of a cross-talk between monocyte lipid accumulation, inflammation and changes in cell surface CD1d and MHC-class II in monocytes, which may result in inappropriate recognition events by immune cells and perpetuate chronic inflammation.

Red blood cells carry out T cell growth and survival bioactivities that are sensitive to cyclosporine A.

Red blood cells (RBC) have emerged as a novel regulatory cell type endowed with bioactivities toward activated human T cells. Herein we show that the RBC bioactivities act on intracellular pathways initiated by T cell receptor (TCR)-dependent and -independent stimuli,including IL-2, IL-15, and the mixture of phorbol dibutyrate and ionomycin. The RBC bioactivities preserve the antioxidant status and are capable of rescuing activated T cells from cell death induced by serum deprivation. They are not mediated by glycosylphosphatidylinositol-linked receptors or sialic acids, and kinetic studies revealed that they hasten the entrance into the cell cycle. By using cyclosporine A (CsA) and rapamycin (Rapa) we show that the RBC bioactivities are calcineurin-dependent. Thus, treatment of T cells with CsA, but not Rapa, impaired RBC bioactivities, and preincubation of RBC with CsA completely abolished their bioactivities. We have demonstrated that RBC carry out bioactivities that are sensitive to CsA.

Hepatocytes and IL-15: a favorable microenvironment for T cell survival and CD8+ T cell differentiation.

Human intrahepatic lymphocytes are enriched in CD1d-unrestricted T cells coexpressing NKR. Although the origin of this population remains controversial, it is possible to speculate that the hepatic microenvironment, namely epithelial cells or the cytokine milieu, may play a role in its shaping. IL-15 is constitutively expressed in the liver and has a key role in activation and survival of innate and tissue-associated immune cells. In this in vitro study, we examined whether hepatocyte cell lines and/or IL-15 could play a role in the generation of NK-like T cells. The results show that both HepG2 cells and a human immortalized hepatocyte cell line increase survival and drive basal proliferation of T cells. In addition, IL-15 was capable of inducing Ag-independent up-regulation of NKR, including NKG2A, Ig-like receptors, and de novo expression of CD56 and NKp46 in CD8(+)CD56(-) T cells. In conclusion, our study suggests that hepatocytes and IL-15 create a favorable microenvironment for T cells to growth and survive. It can be proposed that the increased percentage of intrahepatic nonclassical NKT cells could be in part due to a local CD8(+) T cell differentiation.