Characterization of the cytokine network at a single cell level in mice with collagen-induced arthritis using a dual color ELISPOT assay

Development of Nano-Micro Fused LSPR Chip for In Situ Single-Cell Secretion Analysis

Single-cell analysis has become increasingly important in uncovering cell heterogeneity, which has great implications in medicine and biology for a deep understanding of cell characteristics. Owing to its significance, it is vital to create novel devices that can reveal special or unique cells. In this work, we developed a single-cell secretion detection chip consisting of microwells that can trap single cells. Each well is surrounded by Au nanopillars capable of localized surface plasmon resonance (LSPR) measurement. Using microfabrication and nanofabrication techniques, Au nanopillar and microwell structures were fabricated on a COP film. The Au nanopillar was modified with IL-6 antibodies for the direct detection of single-cell secreted IL-6 via LSPR absorbance peak shift. Specific IL-6 detection was successfully demonstrated using a null and IL-6 oversecreting Jurkat cell. A high single-cell trapping efficiency of over 80% was also achieved. Overall, the development of this single-cell secretion detection chip with a simple LSPR measurement setup represents a significant development in the field of cell biology and immunology, providing researchers with a powerful tool for studying individual cells and their secreted cytokines, and is useful for point-of-care testing (POCT) diagnostics.

Real-Time Monitoring and Detection of Single-Cell Level Cytokine Secretion Using LSPR Technology

Cytokine secretion researches have been a main focus of studies among the scientists in the recent decades for its outstanding contribution to clinical diagnostics. Localized surface plasmon resonance (LSPR) technology is one of the conventional methods utilized to analyze these issues, as it could provide fast, label-free and real-time monitoring of biomolecule binding events. However, numerous LSPR-based biosensors in the past are usually utilized to monitor the average performance of cell groups rather than single cells. Meanwhile, the complicated sensor structures will lead to the fabrication and economic budget problems. Thus, in this paper, we report a simple synergistic integration of the cell trapping of microwell chip and gold-capped nanopillar-structured cyclo-olefin-polymer (COP) film for single cell level Interleukin 6 (IL-6) detection. Here, in-situ cytokine secreted from the trapped cell can be directly observed and analyzed through the peak red-shift in the transmittance spectrum. The fabricated device also shows the potential to conduct the real-time monitoring which would greatly help us identify the viability and biological variation of the tested single cell.

Membrane Microplates for One- and Two-Color ELISPOT and FLUOROSPOT Assays

Membranes are widely used as protein blotting matrices for a large variety of research applications including western blotting and enzyme-linked immunospot assay (ELISPOT). The largest advantage of using membranes versus solid plastic support is the porosity of membranes allowing for immobilization of high concentrations of proteins and antibodies which, in turn, increases the sensitivity of detection. Similar to plastic surfaces, polyvinylidene difluoride (PVDF) and nitrocellulose membranes create good microenvironment for live cells cultured in vitro and do not interfere with cellular physiology. It appears that PVDF-backed microplates are a golden standard for ELISPOT assays: such plates are inexpensive, easy to use and after assay development, membranes can be removed from the plates and archived. Given the convenience and reliability of membrane microplates, they are widely used in ELISPOT assays for basic research and clinical trials. The ELISPOT assay is an antibody "sandwich" technique aimed at trapping cell-secreted molecules between capture and detection antibodies, followed by either chromogenic enzymatic or fluorescence detection. This review covers the principles of the ELISPOT assay on membrane microplates including single-color and two-color detection techniques with the emphasis on assay design, choosing membrane microplates, and troubleshooting protocols.

ELISPOT assay as a tool to study oxidative stress in lymphocytes

Enzyme-linked immuno spot (ELISPOT) assay is widely used for vaccine development, cancer and AIDS research, and autoimmune disease studies. The output of ELISPOT assay is a formation of colored spots which appear at the sites of cells releasing cytokines, with each individual spot representing a single cytokine-releasing cell. We worked out a protocol to study oxidative stress in human peripheral blood lymphocytes by determining their potency to secrete IFN-gamma, IL-2, IL-4, IL-5, IL-8, and TNF-alpha in response to acute treatment with hydrogen peroxide. We show that hydrogen peroxide-induced oxidative stress can cause a ∼twofold decrease in the number of lymphocytes secreting the TH1 cytokines IFN-gamma and IL-2, as well as chemokines IL-8 and TNF-alpha. However, the number of cells secreting TH2 cytokines IL-4 and IL-5 in hydrogen -peroxide-treated group did not change. It appears that oxidative stress may affect TH1-TH2 cytokine secretion -balance which, in turn, may underlie developments of various pathological conditions. This protocol can be easily modified to study the effects of many other oxidative stress compounds.

Combining ELISPOT and ELISA to measure amounts of cytokines secreted by a single cell

Enzyme-linked immunospot (ELISPOT) assay allows for the determination of the frequency of -cytokine-secreting cells, but does not answer the question of how much cytokine is secreted per cell. In our study, we combined ELISPOT and ELISA assays and developed a protocol to calculate the amount of IFN gamma secreted by each cell. A suspension of human peripheral blood mononuclear cells was split into two pools and cells from one pool were cultured in a regular ELISPOT plate, whereas cells from the other pool were cultured in an uncoated, "blank," ELISPOT plate. After finishing the incubations, the amount of IFN gamma was measured by ELISA in culture media collected from both plates. The "blank" plate served to measure a total amount of secreted IFN gamma, whereas the ELISPOT plate served to measure the amount of unbound (UB) IFN gamma. Subtracting the amount of unbound IFN gamma from its total amount and dividing it by the number of spots in the ELISPOT plate allows for the calculation of the average amount of IFN gamma in a spot formed by a single cell.

Effect of a cocoa flavonoid-enriched diet on experimental autoimmune arthritis

Previously we established that a cocoa-enriched diet in young rats reduces specific antibody production and the T helper (Th) lymphocyte proportion in lymphoid tissues. The aim of the present study was to ascertain the modulatory ability of a cocoa flavonoid-enriched diet on collagen-induced arthritis (CIA), which is mediated by anti-collagen autoantibody response and Th lymphocyte activation. Female Louvain (LOU) rats were fed with a cocoa-enriched diet, beginning 2 weeks before CIA induction. Hind-paw swelling and serum cytokine and anti-collagen antibody concentrations were determined. Anti-collagen antibody-secreting cell counts and lymphocyte subset proportions were established in inguinal lymph nodes (ILN). Reactive oxygen species (ROS), nitric oxide (NO) and TNFα produced by peritoneal macrophages were determined. Although arthritic cocoa-fed rats showed a similar hind-paw swelling time course as the arthritic animals fed a standard diet, the cocoa intake was able to decrease specific IgG2a, IgG2b and IgG2c titres. Moreover, cocoa intake in CIA rats reduced ROS production, TNFα and NO release from peritoneal macrophages, and decreased the Th:cytotoxic T cell ratio in ILN. In conclusion, a cocoa flavonoid-enriched diet in LOU rats with CIA produced no effect on hind-paw swelling but was able to modulate the specific antibody response and also the Th lymphocyte proportion, as well as the synthesis of pro-inflammatory mediators from peritoneal macrophages. Therefore, a cocoa-enriched diet could be a good adjuvant therapy in disorders with oxidative stress or autoimmune pathogenesis.

Marginal zone B cells are naturally reactive to collagen type II and are involved in the initiation of the immune response in collagen-induced arthritis

Antibodies against type II collagen (CII) are essential for development of collagen-induced arthritis (CIA), but how and where the B-cell response to CII is initiated is not fully known. We show here that naive DBA/1 mice display naturally reactive IgM and IgG anti-CII producing B cells prior to immunization. The CII-reactive B cells were observed in the spleen and recognized as marginal zone (MZ) B cells. After CII immunization, CII-specific B cells expanded rapidly in the spleen, in contrast to the lymph nodes, with the initial response derived from MZ B cells and later by follicular (FO) B cells. This was evident despite that the MZ B cells were subject to stringent tolerance mechanisms by having a greater Fc gamma receptor IIb expression than the FO B cells. Further, the MZ B cells migrated to the FO areas upon immunization, possibly providing antigen and activating FO T cells and subsequently FO B cells. Thus, around CIA onset increased numbers of IgG anti-CII producing FO B cells was seen in the spleen, which was dominated by IgG2a- and IgG2b-positive cells. These data demonstrate that CII-reactive MZ B cells are present before and expand after CII immunization, suggesting an initiating role of MZ B cells in the development of CIA.

Exercise prevents the effects of experimental arthritis on the metabolism and function of immune cells

Active lymphocytes (LY) and macrophages (MPhi) are involved in the pathophysiology of rheumatoid arthritis (RA). Due to its anti-inflammatory effect, physical exercise may be beneficial in RA by acting on the immune system (IS). Thus, female Wistar rats with type II collagen-induced arthritis (CIA) were submitted to swimming training (6 weeks, 5 days/week, 60 min/day) and some biochemical and immune parameters, such as the metabolism of glucose and glutamine and function of LY and MPhi, were evaluated. In addition, plasma levels of some hormones and of interleukin-2 (IL-2) were also determined. Results demonstrate that CIA increased lymphocyte proliferation (1.9- and 1.7-fold, respectively, in response to concanavalin A (ConA) and lipopolysaccharide (LPS)), as well as macrophage H(2)O(2) production (1.6-fold), in comparison to control. Exercise training prevented the activation of immune cells, induced by CIA, and established a pattern of substrate utilization similar to that described as normal for these cells. Exercise also promoted an elevation of plasma levels of corticosterone (22.2%), progesterone (1.7-fold) and IL-2 (2.6-fold). Our data suggest that chronic exercise is able to counterbalance the effects of CIA on cells of the IS, reinforcing the proposal that the benefits of exercise may not be restricted to aerobic capacity and/or strength improvement.

ELISPOT assay on membrane microplates

Membranes used for western blotting can be also used for ELISPOT, an enzyme-linked immunospot assay, which allows determining frequencies of cytokine-secreting immune system cells. In addition to their high antibody-retaining capacity PVDF and NC membranes provide good support to immune system cells cultured in vitro and do not affect their physiology. ELISPOT assays utilizing membrane-backed microplates are used in many areas of research including vaccine development, HIV research, cancer and infection disease research, autoimmune disease, and allergy research.ELISPOT utilizes the same antibody "sandwich" technique as enzyme-linked immunosorbent assay, but unlike the latter ELISPOT belongs to state-of-the-art techniques when outcome of the assay depends on skills and accuracy of the operator, a thorough selection of matched pairs of capture and detection antibodies, and using appropriate staining reagents. This review covers basics of ELISPOT assay including its immunochemical design, selection of reagents and membrane microplates, and some troubleshooting recommendations.

Analysing the effect of novel therapies on cytokine expression in experimental arthritis

Type II collagen-induced arthritis (CIA) is an animal model of rheumatoid arthritis that has been used extensively to address questions of disease pathogenesis and to validate novel therapeutic targets. Susceptibility to CIA is strongly associated with major histocompatibility complex class II genes, and the development of arthritis is accompanied by a robust T- and B-cell response to type II collagen. The main pathological features of CIA include proliferative synovitis with infiltration of inflammatory cells, pannus formation, cartilage degradation, erosion of bone and fibrosis. Pro-inflammatory cytokines, such as tumour necrosis factor alpha and interleukin-1beta, are expressed in the arthritic joints in both murine CIA and human rheumatoid arthritis, and blockade of these molecules results in amelioration of disease. Hence, there is a great deal of interest in the development of small-molecular-weight inhibitors of pro-inflammatory cytokines. There is also interest in the development and testing of drugs with the capacity to modulate the immune pathways involved in driving the inflammatory response in arthritis. For these reasons, there is a need to monitor the effect of novel treatments on cytokine expression in vivo. In this review, we outline the various techniques used to detect cytokines in experimental arthritis and describe how these techniques have been used to quantify changes in cytokine expression following therapeutic intervention.

[Detection by flow cytometry of T cell subsets secreting IL-2 and UFNy(Gamma): optimalisation for the technic and the establishment of reference values]

A dysregulation in Th1/Th2 balance has been described for different pathological situations. Knowing the cytokine profile in a given pathology could assist in understanding the disease mechanism and in choosing an immune intervention most effective for the management of this condition. In this work, the production of two Th1 cytokines, IL-2 and IFN- gamma, was analyzed for different T-cell subsets from 20 normal subjects (mean age 33.5 years) and reference values were defined using the flow cytometric analyses. The optimum operating conditions were set as following: mononuclear cells were stimulated with PMA (20 ng/ml) and ionomycin (1 uM) for 6 h in the presence of brefeldin A (10 ug/ml). Cells were fixed with 4% paraformaldehyde and then dually stained, with anti-CD3 or anti-CD4 or anti-CD8 for the membrane and with anticytokine antibody for the intracytoplasma after being permeabilized with 0.5% saponine solution. The frequency determination of cells that produce IL-2 or IFN-gamma revealed large 95% confidence intervals: (CD3-IL-2: 4.60-10.67%, CD8-IL-2: 1.47-23%, CD3-IFN-gamma: 2,97-32,49%, CD4-IFN-gamma: 2.83-21%, CD8-IFN-gamma: 4.60-35.28%). CD4+ lymphocytes produce the majority of IL-2 (85 vs 13% for CD8+). For IFN-gamma, the situation is more balanced, but the CD4+ lymphocytes remain the predominant producer cells (63 vs. 41%).

The effect of triptolide on CD4+ and CD8+ cells in Peyer's patch of SD rats with collagen induced arthritis

Triptolide is a purified component from a traditional Chinese herb Tripterygium wilfordii Hook F. It has been shown to have anti-inflammatory and immunosuppressive activities by its inhibitory effect on T cells. But the effect of triptolide on Peyer's patch cells is unknown. Enteric mucosal immune system, including Peyer's patch, is regarded as one of the sites for inducing immunity tolerance, and this intolerance effect has been used to induce oral tolerance which can considerably reduce arthritis severity in several models of experimental polyarthritis and RA patients. In this study, we investigated the effect of triptolide on the Peyer's patch cells and peripheral lymphocytes in collagen induced arthritis (CIA) in rats. CIA in rat is a widely studied animal model of inflammatory polyarthritis with similarities to rheumatoid arthritis (RA). Our data show that triptolide could lower the arthritic scores and delay the onset of CIA. There are more Peyer's patches in triptolide treated rats than in control rats, while there is no difference in Peyer's patch numbers between CIA rats and triptolide treated rats. In the Peyer's patch, more CD4+ cells are observed in CIA rats, and the numbers of CD4+ cells in triptolide treated rats and control rats are similar. While more CD8+ cells are observed in triptolide treated rats, and the numbers of CD8+ cells in CIA rats and control rats are similar. In periphery, more CD4+ cells and less CD4+ cells in CIA rats and triptolide treated rats are respectively observed. Therefore, the regulation on Peyer's patch might explain some of the immunosuppressive activities of triptolide, and enteric immune response might be actively involved in CIA pathogenesis. It is suggested that the Peyer's patch is one of the primary targets of the immunosuppressive activity of triptolide.

[Development of the method for analysis of the cytokine balance shift associated with diseases]

A dual-color enzyme-linked immunospot (ELISPOT) assay enabled us to analyze three types of cytokine-secreting cells simultaneously. T helper (Th) cells can be subdivided into at least two distinct functional subsets based on their cytokine secretion profiles. The first type of clones (Th1) produces interleukin-2 (IL-2) and interferon-gamma (IFN-gamma), but not IL-4 or IL-5. The second type of clones (Th2) produces IL-4 and IL-5, but not IL-2 or IFN-gamma. Furthermore, the presence of the third type (Th0) of cell, which is a precursor of Th1 or Th2 cells, has been demonstrated to produce both Th1- and Th2-type cytokines. The dual-color ELISPOT assay was developed to differentiate these three subtypes of Th cells in an identical well. In the system, the red spots corresponding to IL-2-secreting cells (Th1) were developed with horseradish peroxidase and aminoethylcarbazole/H(2)O(2). The light-blue spots corresponding to IL-4-secreting cells (Th2) were developed with alkaline phosphatase and Vector blue (chromogenic substrate for alkaline phosphatase). The mixed-colored (indigo) spots corresponding to both types of cytokine-secreting cells (Th0-cells) were developed with both chromogenic substrates. With this system, we could detect the IL-2- and/or IL-4-secreting cells simultaneously in a murine spleen cell or human peripheral mononuclear cell preparation.

A human dual-color enzyme-linked immunospot assay for simultaneous detection of interleukin 2- and interleukin 4-secreting cells

The enzyme-linked immunospot (ELISPOT) assay is an efficient technique for the enumeration of single cells secreting antibodies and cytokines. For simultaneous differentiation of individual cells producing interleukin-2 (IL-2) and interleukin-4 (IL-4) at a single cell level in human peripheral blood mononuclear cells (PBMCs), a human dual-color ELISPOT assay has been optimized. In the present system, the red spots corresponding to IL-2-secreting cells (T helper type 1, Th1, cells) were developed with horseradish peroxidase and the amino ethyl carbazole (AEC)/H2O2. The blue spots corresponding to IL-4-secreting cells (T helper type 2, Th2, cells) were developed with an alkaline phosphatase and the Vector blue. The usefulness of the assay method was tested. With this system, we could detect the IL-2- and IL-4-secreting cells simultaneously in human PBMCs of a juvenile rheumatoid arthritis (JRA) patient. This procedure provides useful information on clinical immune disorders.

Participation of Endogenous Dehydroepiandrosterone and Its Sulfate in the Pathology of Collagen-Induced Arthritis in Mice

We have investigated the serum levels of dehydroepiandrosterone (DHEA) and DHEA sulfate (DHEAS) in type II collagen (CII)-induced arthritis (CIA) DBA/1J mice, an experimental model of human rheumatoid arthritis (RA). Serum levels of DHEA and DHEAS were measured by EIA and GC/MS, respectively. Sera were obtained from the mice on day 6, 13, 28 and 48 after the CII treatment. The disease onset of CIA was observed from day 28 (7%) to day 48 (80%) after CII immunization. The serum concentration of DHEA on day 13 did not differ from that on day 6 in CIA mice and untreated controls. Serum levels of DHEA on day 28 and 48 were significantly low compared with those on day 6 in controls. However, in CIA mice, DHEA levels on day 28 and 48 were not decreased from those on day 6. No difference in the serum DHEAS level on day 13 compared with day 6 was observed in either control or CIA mice. A significant decrease of DHEAS levels on day 28 and 48 compared with day 6 was found in both groups. The time point for the retention of DHEA in CIA mice, day 28 and day 48, coincided with the disease onset of CIA. In conclusion, endogenous DHEA may be produced as a result of physiological response for the protection against CIA.

Escherichia coli heat-labile enterotoxin B subunit prevents autoimmune arthritis through induction of regulatory CD4+ T cells

OBJECTIVE

The receptor-binding B subunit of Escherichia coli heat-labile enterotoxin (EtxB) is a highly stable, nontoxic protein that is capable of modulating immune responses. This study was conducted to determine whether mucosal administration of EtxB can block collagen-induced arthritis (CIA) and to investigate the mechanisms involved.

METHODS

Clinical arthritis in DBA/1 mice was monitored following mucosal administration of EtxB on 4 occasions. The dependence of disease prevention on receptor binding by EtxB and the associated alterations to the immune response to type II collagen (CII) were assessed. Adoptive transfer experiments and lymph node cell cocultures were used to investigate the underlying mechanisms.

RESULTS

Both intranasal and intragastric delivery of EtxB were effective in preventing CIA; a 1-microg dose of EtxB was protective after intranasal administration. A non-receptor-binding mutant of EtxB failed to prevent disease. Intranasal EtxB lowered both the incidence and severity of arthritis when given either at the time of disease induction or 25 days later. EtxB markedly reduced levels of anti-CII IgG2a antibodies and interferon-gamma (IFNgamma) production while not affecting levels of IgG1, interleukin-4 (IL-4), or IL-10. Disease protection could be transferred by CD4+ T cells from treated mice, an effect that was abrogated upon depletion of the CD25+ population. In addition, CD4+CD25+ T cells from treated mice were able to suppress anti-CII IFNgamma production by CII-primed lymph node cells.

CONCLUSION

Mucosal administration of EtxB can be used to prevent or treat CIA. Modulation of the anti-CII immune response by EtxB is associated with a reduction in Th1 cell reactivity without a concomitant shift toward Th2. Instead, EtxB mediates its effects through enhancing the activity of a population of CD4+ regulatory T cells.

The genetic and immunopathological processes underlying collagen-induced arthritis

Animal models of rheumatoid arthritis (RA) have provided substantial insights into basic pathogenic mechanisms of chronic inflammatory arthritis and autoimmune disease in general. Of the variety of models reported, collagen-induced arthritis (CIA) has been the most characterized in terms of both its pathogenesis and its underlying immunological basis. Collagen-induced arthritis has also been the model of choice in terms of testing potential new therapeutic agents for the treatment of human RA. Nevertheless, the complex nature of the balance between T-cell cytokines and the chronic inflammatory processes is only recently becoming clear. This review focuses on these developments, highlighting their implications for our understanding of RA and for the use of CIA as a suitable animal model.

ELISPOT assay to measure antigen-specific murine CD8(+) T cell responses

The enzyme-linked immunospot technique (ELISPOT) relies on the visualization of cytokine secretion by individual T cells following in vitro stimulation with antigen. This assay has been developed and standardized for the quantitative detection of antigen-specific CD8(+) T cells in mice subjected to different immunization protocols [J. Immunol. Methods 181 (1995) 45]. We have identified important variables that affect the efficacy of the ELISPOT assay and in this protocol we describe this methodology in detail. As a model, we used the production of interferon-gamma by CD8(+) T cells from peripheral blood, spleen and liver of mice immunized with malaria sporozoites expressing the H-2K(d)-restricted SYVPSAEQI. This protocol has also been used successfully to detect Th1 and Th2 epitope specific CD4(+) T cells.

[Cytokine balance in the pathogenesis of rheumatoid arthritis]

Rheumatoid arthritis (RA) is a common, frequently severe, chronic inflammatory disease. Although the cause of RA remains unknown, recent advances in understanding its pathogenesis have been substantial. Despite the use of a variety of medications, the treatment of RA is not fully effective in most patients. A T-helper type 1 (Th1)/T-helper type 2 (Th2) cytokine imbalance has been suggested to be of pathogenic importance in several diseases. In this review, the information of cytokine balance in both the experimental model of arthritis and patients with arthritis were summarized. Furthermore, to characterize the cytokine balance at a single cell level, we analyzed the subtypes of cytokine-secreting cells in an experimental model of arthritis using a dual color enzyme-linked immunospot assay (Stardust assay) which we newly developed. These information including our findings might provide us the clue for diagnosis and therapy of arthritis.