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Exaggerated human monocyte IL-10 concomitant to minimal TNF-alpha induction by heat-shock protein 27 (Hsp27) suggests Hsp27 is primarily an antiinflammatory stimulus.

Unlike more well-studied large heat shock proteins (hsp) that induce both T cell antiinflammatory (IL-10, IL-4) and macrophage proinflammatory (TNF-α, IL-15, IL-12) cytokines, hsp27, a small hsp, has been primarily identified as a substrate of mitogen-activated protein kinase-activated protein kinase-2 involved in the p38 signaling pathway and activated during monocyte IL-10 production. Hsp27 can also act as an endogenous protein circulating in the serum of breast cancer patients and a protein whose induction correlates to protection from LPS shock. However, the cytokine-stimulating properties of hsp27 have been unexplored. In this study, exogenous hsp27 is demonstrated for the first time as a potent activator of human monocyte IL-10 production, but only a modest inducer of TNF-α. Although exogenous hsp27 stimulation activated all three monocyte mitogen-activated protein kinase pathways (extracellular signal-related kinase (ERK) 1/2, c-Jun N-terminal kinase, and p38), only p38 activation was sustained and required for hsp27 induction of monocyte IL-10, while both ERK 1/2 and p38 activation were required for induction of TNF-α when using the p38 inhibitor SB203580 or the ERK inhibitor PD98059. Hsp27’s transient activation of the c-Jun N-terminal kinase pathway, which can down-regulate IL-10, may contribute to its potent IL-10 induction. Hsp27’s ERK 1/2 activation was also less sustained than activation by stimuli like LPS, possibly contributing to its modest TNF-α induction. The failure of either PD98059 or anti-TNF-α Ab to substantially inhibit IL-10 induction implied that hsp27 induces IL-10 via activation of p38 signaling independently of TNF-α activation and may be predominantly an antiinflammatory monokine stimulus.

High Dynamic Range Characterization of the Trauma Patient Plasma Proteome

Although human plasma represents an attractive sample for disease biomarker discovery, the extreme complexity and large dynamic range in protein concentrations present significant challenges for characterization, candidate biomarker discovery, and validation. Herein we describe a strategy that combines immunoaffinity subtraction and subsequent chemical fractionation based on cysteinyl peptide and N-glycopeptide captures with two-dimensional LC-MS/MS to increase the dynamic range of analysis for plasma. Application of this “divide-and-conquer” strategy to trauma patient plasma significantly improved the overall dynamic range of detection and resulted in confident identification of 22,267 unique peptides from four different peptide populations (cysteinyl peptides, non-cysteinyl peptides, N-glycopeptides, and non-glycopeptides) that covered 3654 different proteins with 1494 proteins identified by multiple peptides. Numerous low abundance proteins were identified, exemplified by 78 “classic” cytokines and cytokine receptors and by 136 human cell differentiation molecules. Additionally a total of 2910 different N-glycopeptides that correspond to 662 N-glycoproteins and 1553 N-glycosylation sites were identified. A panel of the proteins identified in this study is known to be involved in inflammation and immune responses. This study established an extensive reference protein database for trauma patients that provides a foundation for future high throughput quantitative plasma proteomic studies designed to elucidate the mechanisms that underlie systemic inflammatory responses.

Cell-specific expression and pathway analyses reveal alterations in trauma-related human T cell and monocyte pathways.

Monitoring genome-wide, cell-specific responses to human disease, although challenging, holds great promise for the future of medicine. Patients with injuries severe enough to develop multiple organ dysfunction syndrome have multiple immune derangements, including T cell apoptosis and anergy combined with depressed monocyte antigen presentation. Genome-wide expression analysis of highly enriched circulating leukocyte subpopulations, combined with cell-specific pathway analyses, offers an opportunity to discover leukocyte regulatory networks in critically injured patients. Severe injury induced significant changes in T cell (5,693 genes), monocyte (2,801 genes), and total leukocyte (3,437 genes) transcriptomes, with only 911 of these genes common to all three cell populations (12%). T cell-specific pathway analyses identified increased gene expression of several inhibitory receptors (PD-1, CD152, NRP-1, and Lag3) and concomitant decreases in stimulatory receptors (CD28, CD4, and IL-2Rα). Functional analysis of T cells and monocytes confirmed reduced T cell proliferation and increased cell surface expression of negative signaling receptors paired with decreased monocyte costimulation ligands. Thus, genome-wide expression from highly enriched cell populations combined with knowledge-based pathway analyses leads to the identification of regulatory networks differentially expressed in injured patients. Importantly, application of cell separation, genome-wide expression, and cell-specific pathway analyses can be used to discover pathway alterations in human disease.

Failure of Monocytes of Trauma Patients to Convert to Immature Dendritic Cells is Related to Preferential Macrophage-Colony-Stimulating Factor-Driven Macrophage Differentiation

Following trauma, increased inflammatory monokine activation and depressed APC function can occur simultaneously. These contradictory monocyte (Mφ) dysfunctions could result if postinjury Mφ differentiation preferentially favored inflammatory macrophage (Mac) differentiation over development into the most potent APC, dendritic cells (DC). In this report, Mφ of trauma patients with a depressed MLR induction capacity are, for the first time, shown to be unable to differentiate in vitro to immature CD1a+ DC under the influence of GM-CSF and IL-4. Trauma patient Mφ that retained MLR-inducing capacity had a nonsignificant reduction in DC differentiation capacity. Only patient Mφ populations with depressed differentiation to immature DC (iDC) demonstrated depressed IL-12 and IL-15 production and a continued reduced MLR induction capacity. Neither increased IL-10 production nor decreased CD11c+ DC precursor numbers correlated with depressed Mφ-to-DC differentiation. Instead, these patients’ APC-dysfunctional Mφ populations had increased expression of inflammatory Mac phenotypes (CD64+, CD86low, HLA-DRlow) and up-regulated secretion of M-CSF. M-CSF combined with IL-6 inhibits Mφ-to-iDC differentiation and promotes Mφ-to-Mac differentiation by down-regulating GM-CSFR expression and increasing DC apoptosis. Both depressed GM-CSFR expression and increased Mφ iDC apoptosis, as well as increased expression of CD126 (IL-6R) and CD115 (M-CSFR), were detected in APC-defective patient Mφ. In vitro addition of anti-M-CSF enhanced the IL-4 plus GM-CSF-induced Mφ-to-DC differentiation of these patients. This suggests that, in trauma patients, enhanced Mφ-to-Mac differentiation with concomitant inhibited iDC development is partially due to increased circulating Mφ sensitivity to and production of M-CSF and contributes to postinjury immunoaberrations.

Follicular Lymphoma Intratumoral CD4+CD25+GITR+ Regulatory T Cells Potently Suppress CD3/CD28-Costimulated Autologous and Allogeneic CD8+CD25− and CD4+CD25− T Cells

Regulatory T cells (TR) play a critical role in the inhibition of self-reactive immune responses and as such have been implicated in the suppression of tumor-reactive effector T cells. In this study, we demonstrate that follicular lymphoma (FL)-infiltrating CD8+ and CD4+ T cells are hyporesponsive to CD3/CD28 costimulation. We further identify a population of FL-infiltrating CD4+CD25+GITR+ TR that are significantly overrepresented within FL nodes (FLN) compared with that seen in normal (nonmalignant, nonlymphoid hyperplastic) or reactive (nonmalignant, lymphoid hyperplastic) nodes. These TR actively suppress both the proliferation of autologous nodal CD8+CD25− and CD4+CD25− T cells, as well as cytokine production (IFN-γ, TNF-α and IL-2), after CD3/CD28 costimulation. Removal of these cells in vitro by CD25+ magnetic bead depletion restores both the proliferation and cytokine production of the remaining T cells, demonstrating that FLN T cell hyporesponsiveness is reversible. In addition to suppressing autologous nodal T cells, these TR are also capable of suppressing the proliferation of allogeneic CD8+CD25− and CD4+CD25− T cells from normal lymph nodes as well as normal donor PBL, regardless of very robust stimulation of the target cells with plate-bound anti-CD3 and anti-CD28 Abs. The allogeneic suppression is not reciprocal, as equivalent numbers of CD25+FOXP3+ cells derived from either normal lymph nodes or PBL are not capable of suppressing allogeneic CD8+CD25− and CD4+CD25− T cells, suggesting that FLN TR are more suppressive than those derived from nonmalignant sources. Lastly, we demonstrate that inhibition of TGF-β signaling partially restores FLN T cell proliferation suggesting a mechanistic role for TGF-β in FLN TR-mediated suppression.

Loss of chemokine SDF-1alpha-mediated CXCR4 signalling and receptor internalization in human hepatoma cell line HepG2.

Expression of the chemokine stromal cell-derived factor-1alpha (SDF-1alpha) is absent from many carcinomas, including hepatomas. We note an early signalling defect in the hepatocellular carcinoma (HCC) cell line HepG2 that expresses the CXCR4 receptor and binds biotin-labelled SDF, but fails to stimulate downstream signalling events after engagement with SDF. In HepG2, the SDF/CXCR4 interaction did not result in calcium influx, phosphorylation and internalization of CXCR4, nor in a rapid phosphorylation of p44/42 MAP kinase. There were no CXCR4 mutations in the second chemokine binding loop or C terminal phosphorylation and internalization domains. The downstream signalling machinery in HepG2 appears to be intact since transfection of wild-type CXCR4 restored functional responsiveness. We conclude that HepG2 is unresponsive to SDF stimulation because of a defect located after receptor binding but before the activation of the signalling cascade. A hypothetical blocking molecule could hinder receptor internalization or CXCR4 signalling.

Exogenous heat shock protein 27 uniquely blocks differentiation of monocytes to dendritic cells

Circulating heat shock protein (HSP)‐27 is associated with tumor progression and increased post‐injury infection. Extracellular HSP‐27 might alter monocyte (MO)‐derived DC and/or MΦ function to mediate immunosuppression. HSP‐27 treatment inhibited expression of CD1a and CD1b/c, antigen uptake, and allogeneic T cell induction (MLR) by IL‐4 + GM‐CSF‐differentiated human DC while increasing some MΦ characteristics (↑CD14, ↑CD16, ↑CD163). MO cytokine receptor profiles elicited by 24‐h exogenous HSP‐27 treatment remained supportive of immature DC (iDC) emergence (↑IL‐4R, ↓IL‐6R, ↓M‐CSFR). IL‐10, IL‐6, and M‐CSF (which promote MΦ differentiation) were significantly increased in IL‐4 + GM‐CSF + HSP‐27 MO→iDC differentiation cultures. However, HSP‐27 treatment during MO differentiation to DC increased programmed cell death ligand 1 coinhibitor and depressed CD86 costimulator expression in parallel to decreased iDC MLR activity. This suggested that increased MΦ differentiation was not solely responsible for HSP‐27 reduction of differentiating DC activity. HSP‐27 treatment actually depressed the phagocytic capacity of MO differentiated to MΦ by IL‐10 or M‐CSF culture. CD163 (hemoglobin receptor) expression was depressed on M‐CSF + HSP‐27 MO‐derived MΦ. HSP‐27‐mediated inhibition of MO→iDC differentiation was reversed by p38α & β inhibitor (SB202190) addition or TLR4 receptor modulation. HSP‐27 impaired appropriate MO→iDC and MO→MΦ differentiation modulating expression of receptors necessary for their proper functions. This suggests that endogenous HSP‐27 has immunoregulatory activities which could contribute to immunopathology.

Novel functional interactions between Trk kinase and p75 neurotrophin receptor in neuroblastoma cells.

To understand the functional interactions between the TrkA and p75 nerve growth factor (NGF) receptors, we stably transfected LAN5 neuroblastoma cells with an expression vector for ET‐R, a chimeric receptor with the extracellular domain of the epidermal growth factor receptor (EGFR), and the TrkA transmembrane and intracellular domains. EGF activated the ET‐R kinase and induced partial differentiation. NGF, which can bind to endogenous p75, did not induce differentiation but enhanced the EGF‐induced response, leading to differentiation of almost all cells. A mutated NGF, 3T‐NGF, that binds to TrkA but not to p75 did not synergize with EGF. Enhancement of EGF‐induced differentiation required at least nanomolar concentrations of NGF, consistent with the low‐affinity p75 binding site. EGF may induce a limited number of neuronal cells because it also enhanced apoptosis. Both NGF and a caspase inhibitor reduced apoptosis and, thereby, enhanced differentiation. NGF seems to enhance survival through the phosphatidylinositol‐3 kinase (PI3K) pathway. Consistent with this hypothesis, Akt, a downstream effector of the PI3K pathway, was hyperphosphorylated in the presence of EGF+NGF. These results demonstrate that TrkA kinase initiates differentiation, and p75 enhances differentiation by rescuing differentiating cells from apoptosis via the PI3K pathway. Even though both EGF and NGF are required for differentiation of LAN5/ET‐R cells, only NGF is required for survival of the differentiated cells. In the absence of NGF, the cells die by an apoptotic mechanism, involving caspase‐3. An anti‐p75 antibody blocked the survival effect of NGF. Brain‐derived neurotrophic factor also enhanced cell survival, indicating that in differentiated cells, NGF acts through the p75 receptor to prevent apoptosis.

Microfluidic Leukocyte Isolation for Gene Expression Analysis in Critically Ill Hospitalized Patients

BACKGROUND Microarray technology is becoming a powerful tool for diagnostic, therapeutic, and prognostic applications. There is at present no consensus regarding the optimal technique to isolate nucleic acids from blood leukocyte populations for subsequent expression analyses. Current collection and processing techniques pose significant challenges in the clinical setting. Here, we report the clinical validation of a novel microfluidic leukocyte nucleic acid isolation technique for gene expression analysis from critically ill, hospitalized patients that can be readily used on small volumes of blood. METHODS We processed whole blood from hospitalized patients after burn injury and severe blunt trauma according to the microfluidic and standard macroscale leukocyte isolation protocol. Side-by-side comparison of RNA quantity, quality, and genome-wide expression patterns was used to clinically validate the microfluidic technique. RESULTS When the microfluidic protocol was used for processing, sufficient amounts of total RNA were obtained for genome-wide expression analysis from 0.5 mL whole blood. We found that the leukocyte expression patterns from samples processed using the 2 protocols were concordant, and there was less variability introduced as a result of harvesting method than there existed between individuals. CONCLUSIONS The novel microfluidic approach achieves leukocyte isolation in <25 min, and the quality of nucleic acids and genome expression analysis is equivalent to or surpasses that obtained from macroscale approaches. Microfluidics can significantly improve the isolation of blood leukocytes for genomic analyses in the clinical setting.

Selective activation of peripheral blood T cell subsets by endotoxin infusion in healthy human subjects corresponds to differential chemokine activation

Although activation of human innate immunity after endotoxin administration is well established, in vivo endotoxin effects on human T cell responses are not well understood. Most naive human T cells do not express receptors for LPS, but can respond to endotoxin-induced mediators such as chemokines. In this study, we characterized the in vivo response of peripheral human T cell subsets to endotoxin infusion by assessing alterations in isolated T cells expressing different phenotypes, intracellular cytokines, and systemic chemokines concentration, which may influence these indirect T cell responses. Endotoxin administration to healthy subjects produced T cell activation as confirmed by a 20% increase in intracellular IL-2, as well as increased CD28 and IL-2R α-chain (CD25) expression. Endotoxin induced indirect activation of T cells was highly selective among the T cell subpopulations. Increased IL-2 production (36.0 ± 3.7 to 53.2 ± 4.1) vs decreased IFN-γ production (33.8 ± 4.2 to 19.1 ± 3.2) indicated selective Th1 activation. Th2 produced IL-13 was minimally increased. Differentially altered chemokine receptor expression also indicated selective T cell subset activation and migration. CXCR3+ and CCR5+ expressing Th1 cells were decreased (CXCR3 44.6 ± 3.2 to 33.3 ± 4.6 and CCR5 24.8 ± 2.3 to 12 ± 1.4), whereas plasma levels of their chemokine ligands IFN-γ-inducible protein 10 and MIP-1α were increased (61.4 ± 13.9 to 1103.7 ± 274.5 and 22.8 ± 6.2 to 55.7 ± 9.5, respectively). In contrast, CCR4+ and CCR3 (Th2) proportions increased or remained unchanged whereas their ligands, eotaxin and the thymus and activation-regulated chemokine TARC, were unchanged. The data indicate selective activation among Th1 subpopulations, as well as differential Th1/Th2 activation, which is consistent with a selective induction of Th1 and Th2 chemokine ligands.