Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.22.32 (bromelain)
 1,025 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We describe T560, a tissue culture-adapted B lymphoma derived from the gut-associated lymphoid tissue (GALT) of a (B10 x B10.H-2a H-4b)F1 hybrid mouse. This lymphoma is interesting and useful not only because it bears an unusual IgA receptor, fully described elsewhere, but also because it is potentially capable of presenting antigen to T cells restricted by the MHC of either parent. Here we document that T560 cells are IgG2a kappa +, Ia+, B220+, J11d.2+, CD3-, CD4-, CD5-, Mac 1-, Mac 2-, non-specific esterase-. They bind bromelain-treated mouse RBC (BrMRBC) in a PC chloride-inhibitable manner but do not bind SRBC, ox RBC (ORBC) or TNP-ORBC. Two lines, T560.1 and T560.2, and several clones are available. T560.1 and its clones contain low numbers of IgA rosette-forming cells (RFC), intermediate numbers of IgG2a RFC and moderately high numbers of IgG2b RFC; T560.2 and its clones contain moderately high numbers of IgA RFC and low numbers of both IgG2a and IgG2b RFC. Both lines stimulate both B10 and B10.A cells in mixed lymphocyte reactions (MLR) and present keyhole limpet hemocyanin (KLH) to KLH-reactive T cells. T560.2 populations are, however, more efficient possibly because they have somewhat higher proportions of brightly fluorescent Ia+ cells and secrete larger quantities of lymphokine than T560.1 cells. They present PC-conjugated KLH (PC-KLH) approximately 20 times more efficiently than unconjugated KLH, suggesting that their PC binding receptors function in antigen uptake. They constitutively produce IL-1, IL-4 and IL-6, but not IL-2, IL-5 or TGF beta. Neither their IgA nor their IgG receptor expression is affected by IL-4 or by IFNs-alpha, -beta, or -gamma. In their ability to bind BrMRBC and secrete IL-4, they resemble the CH12 lymphoma but differ from it in that they are of F1 hybrid origin, are CD5-, bear IgG2a rather than IgM, do not bind sheep erythrocytes and have a receptor for IgA not present on CH12.
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PMID:T560: an (H-2b x H-2a) F1 hybrid, phosphorylcholine (PC)-binding, murine B cell lymphoma that bears receptors for IgA and IgG, presents antigen and secretes IL-4. 153 83

A GALT-derived B lymphoma, T560, that bears IgAR is described. T560 is IgG2a kappa +, Ia+, B220+, J11d+, Thy-1-, CD3-, CD4-, CD5-, Mac 1-, Mac 2-, nonspecific esterase negative and binds bromelain-treated mouse RBC but not SRBC or ORBC. It presents antigen, secretes IL-1, IL-4 and IL-6 but not IL-2, IL-5 or TGF beta and appears to be related to the Lyt 1+(CD5) lineage of B cells though it lacks Lyt 1. T560 bears IgAR that, on the cell surface, are completely cross-inhibited by low concentrations of IgM and by high concentrations of IgG2a and IgG2b. They do not appear to represent a cell-surface form of galactosyl transferase. They are inducible by high concentrations of IgA, sensitive to trypsin and insensitive to neuraminidase. They are down-regulated by activation of PKC with PMA, but their recovery is not inhibited by cycloheximide, indicating that they are not degraded or shed. They may either lose their affinity for IgA or be internalized without degradation. Seventy percent of IgA receptor activity is lost when T560 is treated with PI-PLC; part of this loss of activity is due to activation of PKC and is inhibited by staurosporine, but approximately 30% of it is not protected by staurosporine indicating that some, or all, of the IgA receptor of T560 is connected to the cell membrane via a GPI linker. The T560 IgA receptor could be related to the poly-Ig or M cell receptor.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Sensitivity of receptors for IgA on T560, a murine B lymphoma, to phorbol myristate acetate and to phosphatidylinositol-specific phospholipase C. 165 5

Recently, it has emerged that extracellular proteases have specific regulatory roles in modulating immune responses. Proteases may act as signaling molecules to activate the Raf-1/extracellular regulated kinase (ERK)-2 pathway to participate in mitogenesis, apoptosis, and cytokine production. Most reports on the role of protease-mediated cell signaling, however, focus on their stimulatory effects. In this study, we show for the first time that extracellular proteases may also block signal transduction. We show that bromelain, a mixture of cysteine proteases from pineapple stems, blocks activation of ERK-2 in Th0 cells stimulated via the TCR with anti-CD3epsilon mAb, or stimulated with combined PMA and calcium ionophore. The inhibitory activity of bromelain was dependent on its proteolytic activity, as ERK-2 inhibition was abrogated by E-64, a selective cysteine protease inhibitor. However, inhibitory effects were not caused by nonspecific proteolysis, as the protease trypsin had no effect on ERK activation. Bromelain also inhibited PMA-induced IL-2, IFN-gamma, and IL-4 mRNA accumulation, but had no effect on TCR-induced cytokine mRNA production. This data suggests a critical requirement for ERK-2 in PMA-induced cytokine production, but not TCR-induced cytokine production. Bromelain did not act on ERK-2 directly, as it also inhibited p21ras activation, an effector molecule upstream from ERK-2 in the Raf-1/MEK/ERK-2 kinase signaling cascade. The results indicate that bromelain is a novel inhibitor of T cell signal transduction and suggests a novel role for extracellular proteases as inhibitors of intracellular signal transduction pathways.
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PMID:Bromelain, from pineapple stems, proteolytically blocks activation of extracellular regulated kinase-2 in T cells. 1045 95

The protease bromelain from pineapple was suggested for adjuvant therapy of malignant diseases. We studied immunological effects of an orally applied bromelain drug on 16 breast cancer patients in comparison with healthy donors. Bromelain was applied for 10 days with a daily dose of 3000 F.I.P. units and the immunocytotoxicity of blood monocytes and lymphocytes against the leukemic K562 and MDA-MB-231 mammary carcinoma target cells was determined in vitro. In addition, the expression of the cell surface markers CD44, CD16, CD11a and CD62L on lymphocytes and the secretion of IL-2 and IL-1beta from monocytes was measured. Patients leukocytes expressed lower bMAK-, MAK-, NK- and LAK-cell activities, compared with those from healthy donors. Orally applied bromelain increased the reduced bMAK- and MAK-cell activity of patients monocytes about 2-fold. When the patients were classified on the basis of bromelain effects on the monocytic cytotoxicity into bromelain responders and nonresponders, about 40% of the patients responded to bromelain with an increase of cytotoxicity from 7.8% to 54% (bMAK-cell activity) and from 16% to 47% (MAK-cell activity). Bromelain was less effective on the higher cytotoxicity of monocytes from healthy donors, but stimulated the secretion of IL-1beta from monocytes. In contrast, patient monocytes secreted no detectable IL-1beta, before, during and after bromelain treatment. Bromelain had no effects on the impaired patients NK- and LAK-cell activity, but reduced the LAK-cell activity of healthy donors. No IL-2 was found in the supernatants of untreated and treated lymphocytes from healthy donors. Bromelain reduced the expression of CD44, but weakly increased CD11a and CD62L expression on patient lymphocytes, whereas CD16 remained unchanged. In vitro bromelain application to lymphocytes had similar effects, with greater reduction rates of CD44 and CD16 expression. As to coagulation parameters in plasma of healthy donors, the activated partial thromboplastin time was increased from 38 to 46 sec, leaving prothrombin time and plasminogen unchanged. These data suggest, that orally applied bromelain stimulates the deficient monocytic cytotoxicity of mammary tumor patients, which may partially explain its proposed antitumor activity.
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PMID:Effects of oral bromelain administration on the impaired immunocytotoxicity of mononuclear cells from mammary tumor patients. 1052 79

The innate immune response is critical for effective immunity against most pathogens. In this study, we show that bromelain, a mixture of cysteine proteases, can enhance IFN-gamma-mediated nitric oxide and TNFalpha production by macrophages. Bromelain's effect was independent of endotoxin receptor activation and was not caused by direct modulation of IFN-gamma receptors. Instead, bromelain either enhanced or acted synergistically with IFN-gamma receptor-mediated signals. These effects were seen in both RAW 264.7, a macrophage cell line, and primary macrophage populations. Bromelain also increased IL-2- and IL-12-mediated IFN-gamma production by NK cells. These results indicate a potential role for bromelain in the activation of inflammatory responses in situations where they may be deficient, such as may occur in immunocompromised individuals.
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PMID:Bromelain activates murine macrophages and natural killer cells in vitro. 1148 47

The ability to modulate immune responses is a major aim of many vaccine and immunotherapeutic development programs. Bromelain, a mixture of cysteine proteases, modulates immunological responses and has been proposed to be of clinical use. However, the identity of the immune cells affected by bromelain and the specific cellular functions that are altered remain poorly understood. To address these shortcomings in our knowledge, we have used both in vitro and in vivo immunological assays to study the effects of bromelain. We found that bromelain enhanced T cell receptor (TCR) and anti-CD28-mediated T cell proliferation in splenocyte cultures by increasing the costimulatory activity of accessory cell populations. However, despite increased T cell proliferation, bromelain concomitantly decreased IL-2 production in splenocyte cultures. Additionally, bromelain did not affect TCR and CD28-induced proliferation of highly purified CD4+ T cells, but did inhibit IL-2 production by these cells. In vivo, bromelain enhanced T-cell-dependent, Ag-specific, B cell antibody responses. Again, bromelain induced a concomitant decrease in splenic IL-2 mRNA accumulation in immunized mice. Together, these data show that bromelain can simultaneously enhance and inhibit T cell responses in vitro and in vivo via a stimulatory action on accessory cells and a direct inhibitory action on T cells. This work provides important insights into the immunomodulatory activity of bromelain and has important implications for the use of exogenous cysteine proteases as vaccine adjuvants or immunomodulatory agents.
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PMID:Bromelain modulates T cell and B cell immune responses in vitro and in vivo. 1148 54