Nanowell-based immunoassays for measuring single-cell secretion: characterization of transport and surface binding.

Arrays of subnanoliter wells (nanowells) provide a useful system to isolate single cells and analyze their secreted proteins. Two general approaches have emerged: one that uses open arrays and local capture of secreted proteins, and a second (called microengraving) that relies on closed arrays to capture secreted proteins on a solid substrate, which is subsequently removed from the array. However, the design and operating parameters for efficient capture from these two approaches to analyze single-cell secretion have not been extensively considered. Using numerical simulations, we analyzed the operational envelope for both open and closed formats, as a function of the spatial distribution of capture ligands, their affinities for the protein, and the rates of single-cell secretion. Based on these analyses, we present a modified approach to capture secreted proteins in-well for highly active secreting cells. This simple method for in-well detection should facilitate rapid identification of cell lines with high specific productivities.

Predicting cytotoxic T-cell age from multivariate analysis of static and dynamic biomarkers.

Adoptive T-cell transfer therapy relies upon in vitro expansion of autologous cytotoxic T cells that are capable of tumor recognition. The success of this cell-based therapy depends on the specificity and responsiveness of the T cell clones before transfer. During ex vivo expansion, CD8+ T cells present signs of replicative senescence and loss of function. The transfer of nonresponsive senescent T cells is a major bottleneck for the success of adoptive T-cell transfer therapy. Quantitative methods for assessing cellular age and responsiveness will facilitate the development of appropriate cell expansion and selection protocols. Although several biomarkers of lymphocyte senescence have been identified, these proteins in isolation are not sufficient to determine the age-dependent responsiveness of T cells. We have developed a multivariate model capable of extracting combinations of markers that are the most informative to predict cellular age. To acquire signaling information with high temporal resolution, we designed a microfluidic chip enabling parallel lysis and fixation of stimulated cell samples on-chip. The acquisition of 25 static biomarkers and 48 dynamic signaling measurements at different days in culture, integrating single-cell and population based information, allowed the multivariate regression model to accurately predict CD8+ T-cell age. From surface marker expression and early phosphorylation events following T-cell receptor stimulation, the model successfully predicts days in culture and number of population doublings with R2=0.91 and 0.98, respectively. Furthermore, we found that impairment of early signaling events following T cell receptor stimulation because of long term culture allows prediction of costimulatory molecules CD28 and CD27 expression levels and the number of population divisions in culture from a limited subset of signaling proteins. The multivariate analysis highlights the information content of both averaged biomarker values and heterogeneity metrics for prediction of cellular age within a T cell population.

DUX4 expression activates JNK and p38 MAP kinases in myoblasts.

Facioscapulohumeral muscular dystrophy (FSHD) is caused by misexpression of the DUX4 transcription factor in skeletal muscle that results in transcriptional alterations, abnormal phenotypes and cell death. To gain insight into the kinetics of DUX4-induced stresses, we activated DUX4 expression in myoblasts and performed longitudinal RNA sequencing paired with proteomics and phosphoproteomics. This analysis revealed changes in cellular physiology upon DUX4 activation, including DNA damage and altered mRNA splicing. Phosphoproteomic analysis uncovered rapid widespread changes in protein phosphorylation following DUX4 induction, indicating that alterations in kinase signaling might play a role in DUX4-mediated stress and cell death. Indeed, we demonstrate that two stress-responsive MAP kinase pathways, JNK and p38, are activated in response to DUX4 expression. Inhibition of each of these pathways ameliorated DUX4-mediated cell death in myoblasts. These findings uncover that the JNK pathway is involved in DUX4-mediated cell death and provide additional insights into the role of the p38 pathway, a clinical target for the treatment of FSHD.

Comparison of cytokines in the peritoneal fluid and conditioned medium of adolescents and adults with and without endometriosis.

PROBLEM: To compare inflammatory- and immune-associated peritoneal cytokines of adolescents and adults with and without endometriosis. METHODS OF STUDY: In a nested case-control study in multiple university-affiliated scientific centers, ten adolescents and thirteen adults with visually and histologically confirmed endometriosis (cases), thirteen adolescents with visually suspected endometriosis but indeterminate (seven patients) or negative (six patients) histology, and fifteen adults undergoing surgery for non-malignant gynecologic disease without endometriosis (controls) underwent laparoscopic aspiration of peritoneal fluid (PF), from which PF and conditioned medium (CM) cytokine levels were assayed. RESULTS: Compared to adults with endometriosis, MCP-3, IL-12p40, MIP-1ß, and IL-15 were significantly higher among adolescents with endometriosis, while TNF-ß and CTACK were lower among adolescents. These differences were similar comparing adolescents with endometriosis to adult controls except for MIP-1ß, which was not statistically different. MIP-1ß was, however, the only cytokine observed to differ between adult cases and controls. There were no significant differences in CM cytokines among the three groups. Results were similar when analyses were restricted to samples collected (a) during menstrual cycle days 1-10, (b) from patients unexposed to exogenous hormones, or (c) from all adolescents despite presence or absence of histologic endometriosis. CONCLUSION: Biologically relevant and statistically significant differences in six PF cytokines were observed and suggest a more pro-invasion cytokine profile among adolescents with endometriosis. Adolescents with endometriosis have unique peritoneal cytokine profiles and molecular behavior when compared to adults with and without endometriosis.

Peritoneal fluid cytokines related to endometriosis in patients evaluated for infertility.

OBJECTIVE: Our aim was to characterize peritoneal cytokine profiles in patients with infertility, with and without endometriosis, to illuminate potential differences in immune profiles that may reflect mechanistic differences between these two patient populations. DESIGN: Cross-sectional study. SETTING: University hospital and research center. PATIENT(S): Women undergoing laparoscopy for infertility investigation (n = 107). INTERVENTION(S): Peritoneal fluid was collected during surgery. Clinical characteristics were registered preoperatively. MAIN OUTCOME MEASURE(S): We determined the concentration of 48 different cytokines from the peritoneal fluid with multiplex immunoassays. Associations between cytokines and clinical findings were assessed with logistic regression and partial least squares discriminant analyses (PLS-DA). RESULT(S): Concentrations of SCGF-ß, IL-8, HGF, and MCP-1 were significantly higher, while IL-13 was significantly lower in the endometriosis group compared with the group without endometriosis. Multiple stepwise logistic regression identified a combination of SCGF-ß, IL-13, and G-CSF concentrations that predicted the presence of endometriosis with 86% sensitivity and 67% specificity. PLS-DA identified a class of 11 cytokines (SCGF-ß, HGF, IL-13, MCP-1, CTACK, MCP-3, M-CSF, LIF, IL-5, IL-9, and IFN-a2) that were more characteristic of endometriosis than nonendometriosis patients. CONCLUSION(S): By combining univariate and multivariate analyses, profiles of cytokines more likely to be enriched or depleted in infertility patients with endometriosis compared with those without endometriosis were identified. These findings may inform future analyses of pathophysiological mechanisms of endometriosis in infertile patients, including dysregulated Th1/Th2 response and mobilization and proliferation of hematopoietic stem cells.

Local remodeling of synthetic extracellular matrix microenvironments by co-cultured endometrial epithelial and stromal cells enables long-term dynamic physiological function.

Mucosal barrier tissues, comprising a layer of tightly-bonded epithelial cells in intimate molecular communication with an underlying matrix-rich stroma containing fibroblasts and immune cells, are prominent targets for drugs against infection, chronic inflammation, and other disease processes. Although human in vitro models of such barriers are needed for mechanistic studies and drug development, differences in extracellular matrix (ECM) needs of epithelial and stromal cells hinder efforts to create such models. Here, using the endometrium as an example mucosal barrier, we describe a synthetic, modular ECM hydrogel suitable for 3D functional co-culture, featuring components that can be remodeled by cells and that respond dynamically to sequester local cell-secreted ECM characteristic of each cell type. The synthetic hydrogel combines peptides with off-the-shelf reagents and is thus accessible to cell biology labs. Specifically, we first identified a single peptide as suitable for initial attachment of both endometrial epithelial and stromal cells using a 2D semi-empirical screen. Then, using a co-culture system of epithelial cells cultured on top of gel-encapsulated stromal cells, we show that inclusion of ECM-binding peptides in the hydrogel, along with the integrin-binding peptide, leads to enhanced accumulation of basement membrane beneath the epithelial layer and more fibrillar collagen matrix assembly by stromal cells over two weeks in culture. Importantly, endometrial co-cultures composed of either cell lines or primary cells displayed hormone-mediated differentiation as assessed by morphological changes and secretory protein production. A multiplex analysis of apical cytokine and growth factor secretion comparing cell lines and primary cells revealed strikingly different patterns, underscoring the importance of using primary cell models in analysis of cell-cell communication networks. In summary, we define a "one-size-fits-all" synthetic ECM that enables long-term, physiologically responsive co-cultures of epithelial and stromal cells in a mucosal barrier format.

Synergistic Communication between CD4+ T Cells and Monocytes Impacts the Cytokine Environment.

Physiological cytokine environments arise from factors produced by diverse cell types in coordinated concert. Understanding the contributions of each cell type in the context of cell-cell communication is important for effectively designing disease modifying interventions. Here, we present multi-plexed measurement of 48 cytokines from a coculture system of primary human CD4+ T cells and monocytes across a spectrum of stimuli and for a range of relative T cell/monocyte compositions, coupled with corresponding measurements from PBMCs and plasma from the same donors. Computational analysis of the resulting data-sets elucidated communication-independent and communication-dependent contributions, including both positive and negative synergies. We find that cytokines in cell supernatants were uncorrelated to those found in plasma. Additionally, as an example of positive synergy, production levels of CXCR3 cytokines IP-10 and MIG, depend non-linearly on both IFNγ and TNFα levels in cross-talk between T cells and monocytes. Overall, this work demonstrates that communication between cell types can significantly impact the consequent cytokine environment, emphasizing the value of mixed cell population studies.