Protective effects of carbonyl iron against multiple low-dose streptozotocin-induced diabetes in rodents

Particulate adjuvants have shown increasing promise as effective, safe, and durable agents for the stimulation of immunity, or alternatively, the suppression of autoimmunity. Here we examined the potential of the adjuvant carbonyl iron (CI) for the modulation of organ-specific autoimmune disease-type 1 diabetes (T1D). T1D was induced by multiple low doses of streptozotocin (MLDS) that initiates beta cell death and triggers immune cell infiltration into the pancreatic islets. The results of this study indicate that the single in vivo application of CI to MLDS-treated DA rats, CBA/H mice, or C57BL/6 mice successfully counteracted the development of insulitis and hyperglycemia. The protective action was obtained either when CI was applied 7 days before, simultaneously with the first dose of streptozotocin, or 1 day after MLDS treatment. Ex vivo cell analysis of C57BL/6 mice showed that CI treatment reduced the proportion of proinflammatory F4/80⁺ CD40⁺ M1 macrophages and activated T lymphocytes in the spleen. Moreover, the treatment down-regulated the number of inflammatory CD4⁺ IFN-γ⁺ cells in pancreatic lymph nodes, Peyer's patches, and pancreas-infiltrating mononuclear cells, while simultaneously potentiating proportion of CD4⁺ IL17⁺ cells. The regulatory arm of the immune system represented by CD3⁺ NK1.1⁺ (NKT) and CD4⁺ CD25⁺ FoxP3⁺ regulatory T cells was potentiated after CI treatment. In vitro analysis showed that CI down-regulated CD40 and CD80 expression on dendritic cells thus probably interfering with their antigen-presenting ability. In conclusion, particulate adjuvant CI seems to suppress the activation of the innate immune response, which further affects the adaptive immune response directed toward pancreatic beta cells.

Ethyl Acetate Extract of Origanum vulgare L. ssp. hirtum Prevents Streptozotocin-Induced Diabetes in C57BL/6 Mice

Type 1 diabetes (T1D) is an autoimmune disease that develops as a consequence of pancreatic β-cell death induced by proinflammatory mediators. Because Origanum vulgare L. ssp. hirtum (Greek oregano) contains antiinflammatory molecules, we hypothesized that it might be beneficial for the treatment of T1D. An ethyl acetate extract of oregano (EAO) was prepared from the leaves by a polar extraction method. Phytochemical composition was determined by liquid chromatography-UV diode array coupled to ion-trap mass spectrometry with electrospray ionization interface (LC/DAD/ESI-MS(n) ). In vitro immunomodulatory effect of EAO was estimated by measuring proliferation (MTT) or cytokine secretion (ELISA) from immune cells. Diabetes was induced by multiple low doses of streptozotocin (MLDS) in male C57BL/6 mice and EAO was administered intraperitoneally for 10 d. Determination of cellular composition (flow cytometry) and cytokine production (ELISA) was performed on 12th d after diabetes induction. EAO suppressed the function of both macrophages and lymphocytes in vitro. In vivo, EAO treatment significantly preserved pancreatic islets and reduced diabetes incidence in MLDS-challenged mice. Besides down-modulatory effect on macrophages, EAO reduced the number of total CD4(+) and activated CD4(+) CD25(+) T cells. Furthermore, EAO affected the number of T helper 1 (Th1) and T helper 17 (Th17) cells through downregulation of their key transcription factors T-bet and RORγT. Because EAO treatment protects mice from development of hyperglycemia by reducing proinflammatory macrophage/Th1/Th17 response, this plant extract could represent a basis for future diabetes therapy.

Ruthenium(II) p-cymene complex bearing 2,2'-dipyridylamine targets caspase 3 deficient MCF-7 breast cancer cells without disruption of antitumor immune response

[Ru(η(6)-p-cym)Cl{dpa(CH2)4COOEt}][PF6] (cym=cymene; dpa=2,2'-dipyridylamine; complex 2) was prepared and characterized by elemental analysis, IR and multinuclear NMR spectroscopy, as well as ESI-MS and X-ray structural analysis. The structural analog without a side chain [Ru(η(6)-p-cym)Cl(dpa)][PF6] (1) as well as 2 were investigated in vitro against 518A2, SW480, 8505C, A253 and MCF-7 cell lines. Complex 1 is active against all investigated tumor cell lines while the activity of compound 2 is limited only to caspase 3 deficient MCF-7 breast cancer cells, however, both are less active than cisplatin. As CD4(+)Th cells are necessary to trigger all the immune effector mechanisms required to eliminate tumor cells, besides testing the in vitro antitumor activity of 1 and 2, the effect of ruthenium(II) complexes on the cells of the adaptive immune system have also been evaluated. Importantly, complex 1 applied in concentrations which were effective against tumor cells did not affect immune cell viability, nor did exert a general immunosuppressive effect on cytokine production. Thus, beneficial characteristics of 1 might contribute to the overall therapeutic properties of the complex.

The NO-modified HIV protease inhibitor as a valuable drug for hematological malignancies: Role of p70S6K

Covalent attachment of NO to the first approved HIV protease inhibitor Saquinavir (Saq-NO) expands the therapeutic potential of the original drug. Apart from retained antiviral activity, the modified drug exerts strong antitumor effects and lower toxicity. In the present study, we have evaluated the sensitivity of different hematological malignancies to Saq-NO. Saq-NO efficiently diminished the viability of Jurkat, Raji, HL-60 and K562 cells. While Jurkat and Raji cells (established from pediatric patients) displayed abrogated proliferative potential, HL-60 and K652 cells (originated from adults) exposed to Saq-NO treatment underwent caspase dependent apoptosis. In addition, similar sensitivity to Saq-NO was observed in mononuclear blood cells obtained from pediatric patients with acute lymphoblastic leukemia (ALL) and adult patients with acute myeloid leukemia (AML). Western blot analysis indicated p70S6 kinase as a possible intracellular target of Saq-NO action. Moreover, the addition of a NO moiety to Lopinavir resulted in improved antitumor potential as compared to the parental compound, suggesting that NO-derived HIV protease inhibitors are a potential new source of anticancer drugs with unique mode of action.

Anti-diabetic actions of carbon monoxide-releasing molecule (CORM)-A1: Immunomodulation and regeneration of islet beta cells

We have recently shown that carbon monoxide releasing molecule (CORM)-A1 prevents type 1 diabetes induced in C57BL/6 mice with multiple low doses of streptozotocin (MLDS) by shifting the Th1/Th17/M1 balance towards a Th2/M2 response. In the present work we tested the hypothesis that CORM-A1 might influence regulatory arm of the immune response, as well as beta cell regeneration. CORM-A1 (2 mg/kg/day) was administered for 10 days to mice induced with MLDS and/or depleted of low dose cyclophosphamide (CY)-sensitive FoxP3+ T regulatory (Treg) cells. Besides monitoring hyperglycaemia, ex vivo analysis of spleen, pancreatic lymph nodes (PLN) and pancreas was performed at the end of treatment. In CORM-A1-treated MLDS-induced mice the improvement of hyperglycaemia was observed only without depletion of CY-sensitive FoxP3+ Treg cells. This was accompanied by decreased levels of interleukin (IL)-12, IL-2 and early activation marker CD25 in the spleen and PLN and increased transforming growth factor (TGF)-β, resulting in reduced lymphocyte proliferation in both organs. In parallel, decreased transcript levels of IL-2, but increased mRNA expression of TGF-β, accompanied with up-regulation of Ki-67 protein expression was observed within pancreas. Together, the data suggested that besides the immunomodulatory potential, CORM-A1 probably induces beta cell regeneration.

In vitro effects of binuclear (η (6)-p-cymene)ruthenium(II) complex containing bridging bis(nicotinate)-polyethylene glycol ester ligand on differentiation pathways of murine Th lymphocytes activated by T cell mitogen

T cell differentiation into distinct T helper (Th) subpopulations is crucial in governing acquired immune responses as well as some inflammatory and autoimmune disorders. This study investigated potential of the novel neutral binuclear ruthenium(II) complexes 1-8 with general formula [{RuCl2(η(6)-p-cym)}2μ-(N(∩)N)] (N(∩)N = bis(nicotinate)- and bis(iso-nicotinate)-polyethylene glycol esters; (3-py)COO(CH2CH2O) n CO(3-py) and (4-py)COO(CH2CH2O) n CO(4-py); n = 1-4), as well as [RuCl2(η(6)-p-cym)(nic)] (R1, nic = nicotinate) and [RuCl2(η(6)-p-cym)(inic)] (R2, inic = isonicotinate) as an immunomodulatory agents capable to direct Th cell differentiation. From all investigated complexes, [{RuCl2(η(6)-p-cym)}2μ-{(3-py)COO(CH2CH2O)4CO(3-py)}] (4) was selected for further study because it did not affect splenocyte viability (in concentration up to 50 μM), but significantly reduced secretion of representative Th1 cytokine, IFN-γ induced by T cell mitogen. Besides IFN-γ, 4 inhibited dose dependently expression and production of representative Th17 cytokine, IL-17, in these cells. Otherwise, the production of anti-inflammatory cytokines IL-4 and IL-10 was upregulated. Also, 4 significantly increased CD4(+)CD25(+)FoxP3(+) Treg cell frequency in the activated splenocytes. Moreover, ConA-induced expression of Th1 transcription factors, T-bet and STAT1, as well as of Th17-related protein STAT3 was attenuated upon exposure to 4, while the expression of Th2-related transcription factor GATA3 remained stable. In conclusion, ruthenium(II) complex 4 modulates immune system cell functions in vitro by inhibiting T cell differentiation towards pathogenic Th1/Th17 phenotype and inducing a regulatory phenotype characterized by IL-10 and IL-4 production, which may provide novel therapeutic opportunities for immune-inflammatory and/or autoimmune disorders.

Compound A, a selective glucocorticoid receptor agonist, inhibits immunoinflammatory diabetes, induced by multiple low doses of streptozotocin in mice

BACKGROUND AND PURPOSE

Type 1 diabetes is a multifactorial inflammatory disease that develops as a result of deregulated immune responses, causing progressive autoimmune destruction of insulin-producing beta cells of pancreas. 2-((4-acetoxyphenyl)-2-chloro-N-methyl) ethylammonium chloride, compound A (CpdA), is a selective glucocorticoid receptor (GR) agonist that displays strong anti-inflammatory and immunomodulatory activities. We investigated the therapeutic effectiveness of CpdA in a pharmacological model of type 1 diabetes in mice.

EXPERIMENTAL APPROACH

The utility of CpdA in diabetes prevention was evaluated in vivo through its prophylactic administration to male C57BL/6 mice that received multiple low doses of streptozotocin for immunoinflammatory diabetes induction. The effect of CpdA on disease development was studied by measuring blood glucose and insulin level, histopathological examination, determination of the nature of infiltrating cells, pro- and anti-inflammatory cytokine production, and signalling pathways.

KEY RESULTS

Prophylactic in vivo therapy with CpdA conferred protection against development of immunoinflammatory diabetes in mice by dampening the M1/Th1/Th17 immune response and switching it towards an anti-inflammatory M2/Th2/Treg profile, thus preserving beta cell function.

CONCLUSIONS AND IMPLICATIONS

Anti-diabetic properties of CpdA are mediated through modulation of immune cell-mediated pathways, but without triggering adverse events. These findings provide basic information for the therapeutic use of selective GR agonists in the amelioration of islet-directed autoimmunity.

Novel inhibitors of macrophage migration inhibitory factor prevent cytokine-induced beta cell death

Macrophage migration inhibitory factor is a multifunctional cytokine involved in the regulation of immune processes and also in apoptosis induction. Elevated MIF expression is detrimental for insulin-producing beta cells and MIF inhibition protected beta cells from several cytotoxic insults such as inflammatory cytokines, high fatty acids or high glucose concentrations. Therefore, the aim of this study was to investigate two newly synthesized small molecule MIF inhibitors (K664-1 and K647-1) and to compare them with previously established effects of the prototypical MIF inhibitor, ISO-1. Our results indicate that K664-1 and K647-1 are 160- and 40-fold more effective in inhibition of MIF׳s tautomerase activity than ISO-1. Also, new inhibitors confer beta cell protection from cytokine-triggered apoptosis at significantly lower concentrations than ISO-1. Although all three MIF inhibitors inhibit caspase 3 activity, K664-1 and K647-1 suppress pro-apoptotic BAX protein expression and up-regulate anti-apoptotic Bcl-2 mRNA. Finally, all three MIF inhibitors operate through blockade of nitric oxide production stimulated by cytokines. In conclusion, two novel MIF inhibitors are more potent than ISO-1 and operate through inhibition of the mitochondria-related apoptotic pathway. We propose that these compounds represent a unique class of anti-MIF antagonists that should be further tested for therapeutic use.

Pharmacological application of carbon monoxide ameliorates islet-directed autoimmunity in mice via anti-inflammatory and anti-apoptotic effects

AIMS/HYPOTHESIS

Recent studies have identified carbon monoxide (CO) as a potential therapeutic molecule for the treatment of autoimmune diseases owing to its anti-inflammatory and anti-apoptotic properties. We explored the efficacy and the mechanisms of action of the CO-releasing molecule (CORM)-A1 in preclinical models of type 1 diabetes.

METHODS

The impact of CORM-A1 on diabetes development was evaluated in models of spontaneous diabetes in NOD mice and in diabetes induced in C57BL/6 mice by multiple low-dose streptozotocin (MLDS). Ex vivo analysis was performed to determine the impact of CORM-A1 both on T helper (Th) cell and macrophage differentiation and on their production of soluble mediators in peripheral tissues and in infiltrates of pancreatic islets. The potential effect of CORM-A1 on cytokine-induced apoptosis in pancreatic islets or beta cells was evaluated in vitro.

RESULTS

CORM-A1 conferred protection from diabetes in MLDS-induced mice and reduced diabetes incidence in NOD mice as confirmed by preserved insulin secretion and improved histological signs of the disease. In MLDS-challenged mice, CORM-A1 attenuated Th1, Th17, and M1 macrophage response and facilitated Th2 cell differentiation. In addition, CORM-A1 treatment in NOD mice upregulated the regulatory arm of the immune response (M2 macrophages and FoxP3(+) regulatory T cells). Importantly, CORM-A1 interfered with in vitro cytokine-induced beta cell apoptosis through the reduction of cytochrome c and caspase 3 levels.

CONCLUSIONS/INTERPRETATION

The ability of CORM-A1 to protect mice from developing type 1 diabetes provides a valuable proof of concept for the potential exploitation of controlled CO delivery in clinical settings for the treatment of autoimmune diabetes.

Galectin-3 deficiency protects pancreatic islet cells from cytokine-triggered apoptosis in vitro

Beta cell apoptosis is a hallmark of diabetes. Since we have previously shown that galectin-3 deficient (LGALS3(-/-) ) mice are relatively resistant to diabetes induction, the aim of this study was to examine whether beta cell apoptosis depends on the presence of galectin-3 and to delineate the underlying mechanism. Deficiency of galectin-3, either hereditary or induced through application of chemical inhibitors, β-lactose or TD139, supported survival and function of islet beta cells compromised by TNF-α + IFN-γ + IL-1β stimulus. Similarly, inhibition of galectin-3 by β-lactose or TD139 reduced cytokine-triggered apoptosis of beta cells, leading to conclusion that endogenous galectin-3 propagates beta apoptosis in the presence of an inflammatory milieu. Exploring apoptosis-related molecules expression in primary islet cells before and after treatment with cytokines we found that galectin-3 ablation affected the expression of major components of mitochondrial apoptotic pathway, such as BAX, caspase-9, Apaf, SMAC, caspase-3, and AIF. In contrast, anti-apoptotic molecules Bcl-2 and Bcl-XL were up-regulated in LGALS3(-/-) islet cells when compared to wild-type (WT) counterparts (C57BL/6), resulting in increased ratio of anti-apoptotic versus pro-apoptotic molecules. However, Fas-triggered apoptotic pathway as well as extracellular signal-regulated kinase 1/2 (ERK1/2) was not influenced by LGALS-3 deletion. All together, these results point to an important role of endogenous galectin-3 in beta cell apoptosis in the inflammatory milieu that occurs during diabetes pathogenesis and implicates impairment of mitochondrial apoptotic pathway as a key event in protection from beta cell apoptosis in the absence of galectin-3.

Apotransferrin inhibits interleukin-2 expression and protects mice from experimental autoimmune encephalomyelitis

Transferrin (Tf) has a major role in T cell activation and proliferation. Here, we investigated whether Tf exerts immunomodulatory effects on T cells and in development of T-cell driven experimental autoimmune encephalomyelitis (EAE). While treatment of concanavalin A-stimulated splenocytes with apotransferrin (ApoTf) did not affect release of IL-1β, TNF, IFN-γ, IL-17, IL-4, and IL-10, it markedly and dose-dependently down-regulated synthesis of IL-2 in these cells. ApoTf also inhibited IL-2 generation in purified CD3+ T cells and the effect was accompanied with down-regulation of MAPK p44/42 and NFκB signaling. Despite impeded IL-2 release, proliferation of splenocytes was not inhibited by ApoTf. Importantly, ApoTf ameliorated EAE in mice and significantly reduced ex vivo IL-2 production in proteolipid protein-specific lymphocytes. Thus ApoTf may be a promising beneficial agent for multiple sclerosis.

The role of macrophage migration inhibitory factor in obesity-associated type 2 diabetes in mice

Macrophage migration inhibitory factor (MIF) is implicated in the pathogenesis of several inflammationrelated diseases, including obesity and type 2 diabetes (T2D). However, MIF deficiency itself promotes obesity and glucose intolerance in mice. Here we show that the introduction of a high-fat diet (HFD) further aggravates the parameters of obesity-associated T2D: weight gain and glucose intolerance. Furthermore, in contrast to MIF-KO mice on standard chow, HFD-fed MIF-KO mice develop insulin resistance. Although the clinical signs of obesity-associated T2D are upgraded, inflammation in MIF-deficient mice on HFD is significantly lower. These results imply that MIF possesses a complex role in glucose metabolism and the development of obesity-related T2D. However, the downregulation of inflammation upon MIF inhibition could be a useful tool in short-term T2D therapy for preventing pancreatic islet deterioration.

Macrophage migration inhibitory factor (MIF) enhances palmitic acid- and glucose-induced murine beta cell dysfunction and destruction in vitro

Although several reports suggest a potentially deleterious role of macrophage migration inhibitory factor (MIF) in type 2 diabetes (T2D) pathology, it is still unclear how this pro-inflammatory cytokine acts on pancreatic beta cells. The aim of the present study was to evaluate MIF effects on murine beta cells in the in vitro settings mimicking T2D-associated conditions. Results indicate that recombinant MIF further increased apoptosis of pancreatic islets or MIN6 cells upon exposure to palmitic acid or glucose. This was accompanied by upregulation of several pro-apoptotic molecules. Furthermore, MIF potentiated nutrient-induced islet cell dysfunction, as revealed by lower glucose oxidation rate, ATP content, and depolarized mitochondrial membrane. The final outcome was potentiation of mitochondrial apoptotic pathway. The observed upregulation of nutrient-induced islet cell dysfunction and apoptosis by MIF implicates that silencing MIF may be beneficial for maintaining integrity of endocrine pancreas in obesity-associated T2D.

The immunobiology of apotransferrin in type 1 diabetes

The transferrin (Tf) family of iron binding proteins includes important endogenous modulators of the immune function that may modulate autoimmune diseases. To define more clearly the role of apotransferrin (apoTf) in type 1 diabetes we determined the impact of this protein on type 1 diabetes as investigated in islet cells, animal models and patient sera. First, we demonstrated that recombinant apoTf counteracts the cytokine-induced death of murine pancreatic islet cells. Secondly, human apoTf administration favourably influences the course of type 1 diabetes in animal models, resulting in protection against disease development that was associated with reduction of insulitis and reduced levels of proinflammatory cytokines. Finally, we confirmed that patients with newly diagnosed type 1 diabetes manifest significantly lower apoTf serum levels compared to healthy controls and patients with long-lasting disease. In conclusion, our data suggest the apoTf pivotal role in the perpetuation of type 1 diabetes pathology.

Macrophage migration inhibitory factor deficiency protects pancreatic islets from cytokine-induced apoptosis in vitro

During pathogenesis of diabetes, pancreatic islets are exposed to high levels of cytokines and other inflammatory mediators that induce deterioration of insulin-producing beta cells. Macrophage migration inhibitory factor (MIF) plays a key role in the onset and development of several immunoinflammatory diseases and also controls apoptotic cell death. Because the occurrence of apoptosis plays a pathogenetic role in beta cell death during type 1 diabetes development and MIF is expressed in beta cells, we explored the influence of MIF deficiency on cytokine-induced apoptosis in pancreatic islets. The results indicated clearly that elevated MIF secretion preceded C57BL/6 pancreatic islets death induced by interferon (IFN)-γ + tumour necrosis factor (TNF)-α + interleukin (IL)-1β. Consequently, MIF-deficient [MIF-knock-out (KO)] pancreatic islets or islet cells showed significant resistance to cytokine-induced death than those isolated from C57BL/6 mice. Furthermore, upon exposure to cytokines pancreatic islets from MIF-KO mice maintained normal insulin expression and produced less cyclooxygenase-2 (COX-2) than those from wild-type C57BL6 mice. The final outcome of cytokine-induced islet apoptosis in islets from wild-type mice was the activation of mitochondrial membrane pore-forming protein Bcl-2-associated X protein and effector caspase 3. In contrast, these apoptotic mediators remained at normal levels in islets from MIF-KO mice suggesting that MIF absence prevented initiation of the mitochondrial apoptotic pathway. Additionally, the protection from apoptosis was also mediated by up-regulation of prosurvival kinase extracellular-regulated kinase 1/2 in MIF-KO islets. These data indicate that MIF is involved in the propagation of pancreatic islets apoptosis probably via nuclear factor-κB and mitochondria-related proteins.

Host immune defense against Aspergillus fumigatus: insight from experimental systemic (disseminated) infection

Model of systemic Aspergillus fumigatus infection induced by intravenous application of conidia is suitable for studying important aspects of invasive aspergillosis including relationship between infection and mortality, dissemination of infection and immune mechanisms involved in host resistance to this fungus. Use of this model allows the investigation of both innate and adaptive immune response characteristics in resistant/susceptible host, and investigating the contribution of genetic background and cytokine gene deficiency improves the knowledge of the diversity of mechanisms of immune response to Aspergillus infection. Studying of various aspects of systemic aspergillosis contributes to development of antifungal drugs.

Differential strain-related tissue immune response to sublethal systemic Aspergillus fumigatus infection in mice

Using a nonlethal systemic Aspergillus fumigatus infection, we have recently shown that similarly efficient elimination of fungus from spleens of prototypic Th1 (C57BL/6) and prototypic Th2 (BALB/c) mice is associated with differential immune responses. In light of these data and given the disseminated character of infection, the aim of the present study is to explore whether there are also strain-dependent differences in antifungal responses in peripheral tissues of infected mice. Although similar efficiency of conidia removal was noted in liver and kidneys of both strains, BALB/c mice seemed more prone to tissue injury. Compared with other nonlymphoid organs, lungs proved immunologically the most responsive in systemic aspergillosis. Lower numbers of neutrophils and macrophages in the lungs of infected BALB/c mice, delayed and lower (compared with C57BL/6 mice) expression of their oxidative activity, along with late IFN-γ and upregulated IL-4 production by lung cells might be responsible for slower elimination of A. fumigatus from the lungs of this mouse strain. The data obtained imply that lungs should be viewed as mandatory organ in evaluation of immune-mediated antifungal potential of drugs in models of systemic/disseminated infection and that strain differences noted in tissue responses should be taken into account in these settings.

Phytochemical profile of Rosmarinus officinalis and Salvia officinalis extracts and correlation to their antioxidant and anti-proliferative activity

The goal of this study was to monitor the anti-proliferative activity of Rosmarinus officinalis and Salvia officinalis extracts against cancer cells and to correlate this activity with their phytochemical profiles using liquid chromatography/diode array detection/electrospray ion trap tandem mass spectrometry (LC/DAD/ESI-MS(n)). For the quantitative estimation of triterpenic acids in the crude extracts an NMR based methodology was used and compared with the HPLC measurements, both applied for the first time, for the case of betulinic acid. Both extracts exerted cytotoxic activity through dose-dependent impairment of viability and mitochondrial activity of rat insulinoma m5F (RINm5F) cells. Decrease of RINm5F viability was mediated by nitric oxide (NO)-induced apoptosis. Importantly, these extracts potentiated NO and TNF-α release from macrophages therefore enhancing their cytocidal action. The rosemary extract developed more pronounced antioxidant, cytotoxic and immunomodifying activities, probably due to the presence of betulinic acid and a higher concentration of carnosic acid in its phytochemical profile.

Therapeutic potential of nitric oxide-modified drugs in colon cancer cells

We have examined the influence of the nitric oxide (NO)-modified anti-inflammatory drug (S,R)-3-phenyl-4,5-dihydro-5-isoxasole acetic acid (VGX-1027) named GIT-27NO or the NO-modified antiviral drug saquinavir (Saq) named Saq-NO on two colon cancer cell lines, mouse CT26CL25 and human HCT116. The effects of the drugs on cell viability, apoptosis, proliferation, and metastatic potential were analyzed. The release of NO and oxygen and nitrogen species was also determined. The efficacy of the drugs was evaluated in vivo in BALB/c mice injected with CT26CL25 cells. Both agents suppressed the growth of colon cancer cells in vitro and reduced tumor volume in syngeneic BALB/c mice. However, their mechanisms of action were different because GIT-27NO released larger amounts of nitrite than Saq-NO in cell cultures and its antitumor action depended on the intracellular NO release inside the cells. On the contrary, Saq-NO released barely detectable amounts of NO and its antitumor action was NO-independent. In fact, cotreatment with an NO-peroxynitrite scavenger revealed that GIT-27NO but not Saq-NO acts through peroxynitrite-mediated cell destruction. At the cellular level, GIT-27NO prevalently induced proapoptotic signals followed by caspase-dependent apoptosis. In contrast, Saq-NO blocked cell proliferation, changed the adhesive, migratory, and invasive properties of the cells, and decreased metastatic potential in vivo. In conclusion, differences in NO release and oxidative stress generation between GIT-27NO and Saq-NO resulted in different mechanisms that caused cell death.

Cell-type dependent response of melanoma cells to aloe emodin

Intrinsic characteristics of melanoma cells such as expression of inducible nitric oxide synthase (iNOS), redox status, and activity of signaling pathways involved in proliferation, differentiation and cell death define the response of the cells to the diverse treatments. In this context we compared the effectiveness of herbal antaquinone aloe emodin (AE) against mouse B16 melanoma and human A375, different in initial activity of ERK1/2, constitutive iNOS expression and basal level of reactive oxygen species (ROS). Both cell lines are sensitive to AE treatment. However, while the agent induces differentiation of B16 cells toward melanocytes, in A375 cells promoted massive apoptosis. Differentiation of B16 cells, characterized by enhanced melanin production and tyrosinase activity, was mediated by H(2)O(2) production synchronized with rapid p53 accumulation and enhanced expression of cyclins D1 and D3. Caspase mediated apoptosis triggered in A375 cells was accompanied with Bcl-2 but not iNOS down-regulation. In addition, opposite regulation of Akt-ERK1/2 axis in AE treated B16 and A375 cells correlated with different outcome of the treatment. However, AE in a dose-dependent manner rescued both B16 and A375 cells from doxorubicin- or paclitaxel-induced killing. These data indicate that caution is warranted when AE is administrated to the patients with conventional chemotherapy.

Unique antineoplastic profile of Saquinavir-NO, a novel NO-derivative of the protease inhibitor Saquinavir, on the in vitro and in vivo tumor formation of A375 human melanoma cells

We have recently shown that covalent attachment of the nitric oxide (NO) moiety to the HIV protease inhibitor Saquinavir (Saq) produced a qualitatively new chemical entity, named Saquinavir-NO (Saq-NO), with enhanced anticancer properties and reduced toxicity both in vitro and in vivo. The aim of this study was to address several unanswered questions both on the pharmacological profile of Saq-NO as well as on the in vivo role of NO in the oncogenesis of A375 human melanoma cells. To this end, we have evaluated here the impact of single and combined effects of Saq-NO, Saq, the NO-donor DETA NONOate and the iNOS inhibitor L-NAME on the in vitro as well as in vivo growth of the iNOS positive A375 cells. Our data confirm clear-cut evidence for a strong and powerful anti-melanoma action of Saq-NO that is not duplicable by the combined use of Saq and DETA NONOate. Surprisingly, but also in agreement with the complex and multifaceted role of endogenous NO in A375 cells, both DETA NONOate and L-NAME significantly suppressed the in vivo growth of xenotransplants.

Saquinavir-NO-targeted S6 protein mediates sensitivity of androgen-dependent prostate cancer cells to TRAIL

We previously reported that the NO-modified form of HIV protease inhibitor Saquinavir (Saq) is a potent antitumoral agent efficient against numerous tumor cell lines in vitro and in vivo. In acute toxicity studies, doses of Saq-NO equivalent to DL100 of the parental drug were completely nontoxic. Beside direct effect on malignant cell growth, Saq-NO sensitizes certain type of cells to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-mediated cell death. In this study, we evaluated the effects of Saq-NO on androgen-dependent prostate cancer LNCaP. Saq-NO inhibited both the growth of LNCaP cells in vitro and in xenograft models. Suppression of tumor growth was accompanied with cell cycle arrest in G 0/G 1 phase and established a persistent inhibition of proliferation. Furthermore, Saq-NO reverted sensitivity of LNCaP cells to TRAIL but not to TNF. Treatment of cells with Saq-NO induced transient upregulation of Akt and ERK1/2. This, however, did not represent the primary mode of action of Saq-NO, as elimination with specific inhibitors did not compromise the chemotherapic efficacy of the drug. However, permanent abrogation of phosphorylation of the S6 protein, which is the downstream target of both signaling pathways, was observed. Diminished S6 phosphorylation was associated with re-established sensitivity to TRAIL and reduction of X-linked inhibitor of apoptosis protein (XIAP). In summary, NO modification of Saq led to a new chemical entity with stronger and more pleiotropic antitumor activity than the parental drug.

In vitro and in vivo anticancer action of Saquinavir-NO, a novel nitric oxide-derivative of the protease inhibitor saquinavir, on hormone resistant prostate cancer cells

The NO-derivative of the HIV protease inhibitor saquinavir (Saq-NO) is a nontoxic variant of the parental drug with enhanced anticancer activity on several cell lines. However, it is still unclear whether the p53 status of the target cell might influence the sensitivity to Saq-NO. In this study we evaluated the in vitro and in vivo activity of Saq-NO on the p53-deficient hormone resistant prostate cancer PC-3 cells. We demonstrate that the absence of functional p53 is not essential for the capacity of Saq-NO to reduce prostate cancer cell growth. In contrast to its previously described cytostatic action in B16 and C6 cell lines, Saq-NO exerted cytotoxic effects in PC-3 cells leading to dominant induction of apoptosis and enhanced production of proapoptotic Bim. In addition, differently from saquinavir, Saq-NO restored TRAIL sensitivity that was correlated with increased expression of DR5 independent from ROS/RNS production and YY1 repression. NF-κB activation may be responsible of the Saq-NO induced DR5 expression. Moreover, Saq-NO but not saquinavir, exerted synergistic activity with conventional cytostatic therapy. In agreement with these in vitro studies, Saq-NO inhibited the in vivo growth of PC-3 cells xenotransplants to a greater extent than the parental compound. Taken together, these data indicate that Saq-NO possesses powerful and suitable in vitro and in vivo chemotherapeutic potential to be further studied as a novel drug for the treatment of prostate cancer in the clinical setting.

Mechanisms of modulation of experimental autoimmune encephalomyelitis by chronic Trichinella spiralis infection in Dark Agouti rats

Trichinella spiralis is a helminth that provokes Th2 and anti-inflammatory type responses in an infected host. Our previous studies using Dark Agouti (DA) rats indicated that T. spiralis infection reduced experimental autoimmune encephalomyelitis (EAE) severity in rats. The aim of this study was to analyse the mechanisms underlying EAE suppression driven by T. spiralis infection. Reduced clinical and histological manifestations of the disease were accompanied by increased IL-4 and IL-10 production and decreased IFN-gamma and IL-17 production in draining lymph node cells. This indicates that T. spiralis infection successfully maintains a Th2 cytokine bias regardless of EAE induction. High IL-10 signifies parasite-induced anti-inflammatory and/or regulatory cell responses. Transfer of splenic T cell-enriched population of cells from T. spiralis-infected rats into EAE immunized rats caused amelioration of EAE and in some cases protection from disease development. This population of cells contained higher proportion of CD4(+) CD25(+) Foxp3(+) regulatory cells and produced high level of IL-10 when compared with uninfected rats.

Differential mechanisms of resistance to sublethal systemic Aspergillus fumigatus infection in immunocompetent BALB/c and C57BL/6 mice

Studies of systemic and pulmonary Aspergillus fumigatus infection demonstrated differential susceptibility of inbred mice of various genetic background to lethal outcome, with an opposite pattern of Th1 cytokine interferon-γ (IFN-γ) and Th2 cytokine interleukin-4 (IL-4) in susceptible vs resistant mice. We have shown recently reciprocal IFN-γ and IL-4 expression in spleens of Th1-prone C57BL/6 mice in sublethal systemic aspergillosis. In this study, resistance to systemic (i.v.) A. fumigatus infection was investigated in Th2-prone BALB/c mice by survival rate at different fungal inocula, efficiency of reduction of visceral organ and spleen fungal burden at sublethal conidia dose and splenic immune response to this dose and compared to C57BL/6 mice. No strain differences in survival were noted at three A. fumigatus doses, with similar extent and dynamics of fungal eradication from all organs following sublethal conidia dose injection. Progressive decrease in spleen fungal burden was associated with different dynamics and quality of changes in spleen activity of BALB/c and C57BL/6 mice. Increased spleen mass and cellularity was noted in both strains, with higher values in BALB/c mice at some time points what might be ascribed to peripheral blood cell recruitment, as well as hematopoietic activity and red pulp upgrowth. Infection tipped the balance towards pro-inflammatory antifungal splenic response by a highly increasing IFN-γ and without changing the IL-4 expression in BALB/c mice, in contrast to down-regulating anti-inflammatory (IL-4) and a moderately increasing IFN-γ response in C57BL/6 mice. Jointly, stimulation of IL-17 expression noted in both strains provided an optimal inflammatory milieu in the spleen of infected mice that might have contributed to efficient removal of conidia.

Induction of caspase-independent apoptotic-like cell death of mouse mammary tumor TA3Ha cells in vitro and reduction of their lethality in vivo by the novel chemotherapeutic agent GIT-27NO

The new chemical entity GIT-27NO was created by the covalent linkage of a NO moiety to the anti-inflammatory isoxazoline VGX-1027. The compound has been shown to possess powerful anticancer effects both in vitro and in vivo. However, its effects on nonsolid and metastatic forms of tumors have not yet been investigated. We have studied the effects of GIT-27NO on the highly invasive mouse mammary TA3Ha cell line in vitro and in vivo. In contrast to the conventional exogenous NO donor sodium nitroprusside, GIT-27NO successfully enhanced intracellular NO concentration in TA3Ha cells. Intracellular accumulation of NO was followed by marked decrease in TA3Ha cell viability accompanied by typical apoptotic features. Interestingly, inverted membrane phosphatidylserine residues, reduced volume of nucleus, condensed chromatin, and terminal fragmentation of DNA were associated with inhibited caspase-3 activity and transcription of the genes encoding caspase-3, -8, and -9. In parallel, GIT-27NO rapidly but transiently prevented the loss of p53 through phosphorylation on Ser 20 and provided the necessary signals for the execution of downstream processes without p53 de novo synthesis. The caspase-independent apoptotic-like death process triggered by GIT-27NO could be mediated by markedly down-regulated expression of the antiapoptotic Bcl-2 molecule observed in TA3Ha cells exposed to GIT-27NO. In agreement with these in vitro data, GIT-27NO efficiently suppressed the growth of the ascites form and associated lethality of tumor induced by TA3Ha cells in mice.

Time-course changes in ectonucleotidase activities during experimental autoimmune encephalomyelitis

The aim of the present study was to analyze the activities of extracellular purine metabolizing enzymes, CD39 (apyrase, EC 3.6.1.5) and CD73 (ecto-5' nucleotidase, EC 3.1.3.5) in experimental autoimmune encephalomyelitis (EAE). The levels of ATP, ADP and AMP hydrolysis were analyzed in the blood serum and in the rat spinal cord plasma membrane preparation 8, 15 and 25 days after induction of EAE. The animals were divided in three groups: control (saline), CFA (adjuvant-only) and EAE (CFA and homogenate of spinal cords). Eight days after immunization, ATP, ADP and AMP hydrolysis in the blood serum and spinal cord membrane preparations were unaffected in EAE compared to both, control and CFA group. In the peak of disease, ATP, ADP and AMP hydrolysis in EAE group showed significant decrease in the blood serum and prominent increase in the spinal cord membrane preparation compared to CFA and control group. At the end of illness, as judged by disappearance of clinical manifestation of EAE, ATP, ADP and AMP hydrolysis, although closer to CFA levels, were still significantly different in respect to the CFA group. Modulation of ATP, ADP and AMP hydrolysis suggests that they operate during EAE and might represent the basis of novel therapeutic strategies in immune-mediated diseases, such as MS.

Ribavirin administration alters ectonucleotidase activities in experimental autoimmune encephalomyelitis

The role of extracellular purines and purinoreceptors in the pathophysiology of different neurological disorders is the focus of rapidly expanding area of research. Ectonucleotidases are the enzymes with multiple roles in extracellular nucleotides metabolism and regulation of nucleotidebased intercellular signaling. The aim of present study was to investigate the changes in the ATP, ADP and AMP hydrolyzing activities after ribavirin treatment in spinal cord during experimental autoimmune encephalomyelitis (EAE). Our results demonstrate that ribavirin itself had no significant effect on ectoenzyme activities, when tested in vitro and in vivo on spinal cord crude membrane preparation of intact animals. We observed significant increase in ATP, ADP and AMP hydrolyzing activity in the spinal cord crude membrane preparation in EAE animals at 15 days post immunization compared to control animals. The increase was registered at 28 days post immunization, as well. At same time points, ribavirin treatment decreased ATP, ADP and AMP hydrolyzing activity compared to EAE animals. In addition, no significant changes 8 days post immunization was observed between EAE-induced and ribavirin- treated EAE animals and these levels were similar to control level. Thus, we suppose that ribavirin-induced alteration in ectonucleotidase activities is rather due to its suppression of inflammation, than to its direct action on ATP, ADP and AMP hydrolysis.

Anticancer properties of the novel nitric oxide-donating compound (S,R)-3-phenyl-4,5-dihydro-5-isoxazole acetic acid-nitric oxide in vitro and in vivo

Preclinical studies have shown that nitric oxide (NO)-donating nonsteroidal anti-inflammatory drugs possess anticancer activities. Here, we report in vitro and in vivo studies showing the antitumor effect of the NO-donating isoxazole derivative (S,R)-3-phenyl-4,5-dihydro-5-isoxazole acetic acid (GIT-27NO). GIT-27NO, but not the NO-deprived parental compound VGX-1027, significantly affected viability of both rodent (L929, B16, and C6) and human (U251, BT20, HeLa, and LS174) tumor cell lines. GIT-27NO triggered either apoptotic cell death (e.g., L929 cells) or autophagic cell death (C6 and B16 cells). Moreover, GIT-27NO hampered the viability of cisplatin-resistant B16 cells. NO scavenger hemoglobin completely prevented GIT-27NO-induced death, indicating that NO release mediated the tumoricidal effect of the compound. Increase in intracellular NO upon on the treatment was associated with intensified production of reactive oxygen species, whereas their neutralization by antioxidant N-acetylcysteine resulted in partial recovery of cell viability. The antitumor activity of the drug was mediated by the selective activation of mitogen-activated protein kinases in a cell-specific manner and was neutralized by their specific inhibitors. In vivo treatment with GIT-27NO significantly reduced the B16 melanoma growth in syngeneic C57BL/6 mice. The therapeutic effect occurred at dose (0.5 mg/mouse) up to 160 times lower than those needed to induce acute lethality (80 mg/mouse). In addition, a dose of GIT-27NO five times higher than that found effective in the melanoma model was well tolerated by the mice when administered for 4 consecutive weeks. These data warrant additional studies to evaluate the possible translation of these findings to the clinical setting.

Macrophage migration inhibitory factor (MIF) is necessary for progression of autoimmune diabetes mellitus

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine of the innate immune system that plays a major role in the induction of immunoinflammatory responses. To examine the role of endogenous MIF in the pathogenesis of type 1 diabetes (TID) we evaluated the effects of administration of neutralizing anti-MIF antibodies to NOD mice with accelerated forms of diabetes induced by injection of cyclophosphamide or by transfer of diabetogenic spleen cells. Both accelerated forms of diabetes were markedly reduced by anti-MIF antibody. Furthermore, MIF-deficient (MIF(-/-)) mice were less susceptible to the induction of immunoinflammatory diabetes, insulitis and apoptosis within the endocrine pancreas by multiple low doses of streptozotocin (MLD-STZ) than genetically matched wild type (WT) mice. MIF deficiency resulted in lower proliferation and lymphocyte adhesion, as well as reduced production from the spleens and peritoneal cells of a variety of inflammatory mediators typically associated with development of the disease including IL-12, IL-23, TNF-alpha, and IL-1beta. Furthermore, MIF deletion affected the production of IL-18, TNF-alpha, IL-1beta, and iNOS in the islets of Langerhans. These data, along with the higher expression of IL-4 and TGF-beta observed in the periphery and in the pancreas of MLD-STZ-challenged MIF(-/-) mice as compared to WT controls suggest that MIF deficiency has induced an immune deviation towards protective type 2/3 response. These results suggest that MIF participates in T1D by controlling the functional activity of monocytes/macrophages and T cells and modulating their secretory capacity of pro- and anti-inflammatory molecules.

Astrocytes stimulate interleukin-17 and interferon-gamma production in vitro

Astrocytes play important roles in the complex and as yet not very well understood net of interactions among resident and infiltrating cells during central nervous system (CNS) inflammation. In such an intricate network, cytokines represent an essential means for intercellular communication, and astrocytes are able to affect their generation and/or release. Among various cytokines produced by infiltrating cells, interferon (IFN)-gamma and interleukin (IL)-17 are the focus of this research, because they are pivotal cytokines of helper T-cell type 1 (Th1) and helper T-cell type 17 (Th17), respectively. Importantly, both Th1 and Th17 cells, as well as their cytokines, have been shown to be of importance for the pathogenesis of experimental autoimmune encephalomyelitis (EAE), an animal model of a prototypical CNS disease with inflammatory pathogenesis, multiple sclerosis. Therefore, the influence of astrocytes on the generation of IFN-gamma and IL-17 in concanavalin A- and myelin basic protein-stimulated lymph node cells of healthy rats and rats with developing EAE, respectively, was investigated in vitro. Astrocytes up-regulated IL-17 and IFN-gamma gene expression and protein synthesis in T cells, which coincided with astrocytes' ability to express IL-23 subunit p19 and common IL-12/IL-23 subunit p40 but not IL-12 subunit p35 in the co-cultivations. These results suggest one more way in which astrocytes could contribute to the complex interactions during CNS inflammation.

Control of the of the final stage of immune-mediated diabetes by ISO-1, an antagonist of macrophage migration inhibitory factor

We recently showed that attenuation of inflammatory cytokine MIF with pharmacological inhibitor ISO-1 down-regulates the immune-mediated diabetes in mice. Here we explore the effects of MIF neutralization by ISO-1 on the local inflammatory pathway of the disease. In vivo treatment of mice with ISO-1 inhibited the expression of pro-inflammatory cytokines and iNOS in the pancreatic islets. Moreover, ISO-1 affected in vitro cytokine-induced NO pro?duction by fibroblasts, endothelial cells, insulinoma cells, and pancreatic islets, and rescued ? cells from NO-dependent damage. These results suggest regulatory potential of ISO-1 at the level of the pancreas which can preserve the target tissue from autoimmune attack.

Interactions between infections and immune-inflammatory cells in type 1 diabetes mellitus and inflammatory bowel diseases: evidences from animal models

Type 1 diabetes mellitus (T1D) and inflammatory bowel diseases (IBD) are multifactorial disorders of autoimmune origin. Several microbial agents have been reported to be associated with the development of type 1 diabetes and inflammatory bowel diseases in animal models by different mechanisms. These models which resemble the phenotype of the human disease they mimic, can be very useful to identify important pathogenetic mechanisms, as well as therapeutical targets to treat the disease. This review is focused on the immune inflammatory pathways which are considered to be associated with the pathogenesis T1D and IBD in transgenic mice.

Therapeutic effects of combined treatment with ribavirin and tiazofurin on experimental autoimmune encephalomyelitis development: clinical and histopathological evaluation

Experimental autoimmune encephalomyelitis (EAE) is an animal model of multiple sclerosis (MS) and the helpful tool in preclinical testing of various substances considered for treatment of this human CNS disease. Ribavirin (R) and tiazofurin (T) are purine nucleoside analogues, with the broad spectrum of anti-viral, anti-tumoral and anti-inflammatory properties. We proposed that combined treatment with RT, administrated during the effector phase of EAE, would attenuate disease severity, both clinically and pathologically. Ribavirin was given daily at a dosage of 30 mg/kg and tiazofurin was given at a dosage of 10 mg/kg every other day for 15 days. We detected amelioration of clinical signs and faster recovery in the RT group compared to the control group. Immunohistochemical analyses revealed that RT treatment decrease the number of T cells, macrophages and microglia. In the controls, we detected reactive type of microglia, while in the RT group we noticed ramified/resting form. Demyelination areas and axonal damage were not recorded in the RT group, in contrast to the control group where multiple areas of demyelination zones and axonal loss were found. RT combination treatment suppresses ongoing EAE, prevents demyelination and axonal loss, and therefore may well be the potential therapy for the treatment of MS.

In vitro, ex vivo and in vivo immunopharmacological activities of the isoxazoline compound VGX-1027: Modulation of cytokine synthesis and prevention of both organ-specific and systemic autoimmune diseases in murine models

We have presently studied the in vitro, ex vivo and in vivo immunopharmacological effects of VGX-1027 [(S,R)-3-phenyl-4,5-dihydro-5-isoxasole acetic acid]. This compound reduced the secretion of IL-1beta, TNF-alpha and IL-10 from purified murine macrophages stimulated "in vitro" with lipopolysaccharide (LPS), and it also modified the signaling pathways induced in these cells by LPS entailing reduced activation of NF-kappaB and p38 MAP kinase pathways along with up-regulation of ERK pathways. VGX-1027 appeared to spare T cell function as it was unable to modify the proliferation and/or secretion of IL-2, IFN-gamma and IL-4 induced in purified murine CD4+ T cells from stimulation with either CD3+CD28 or ConA. These effects on macrophages may account for the capacity of VGX-1027 to markedly ameliorate the course of both acute and chronic immunoinflammatory diseases in mice such as carrageenan-induced pleurisy, LPS-induced lethality and type II collagen-induced arthritis. Acute and subacute toxicological studies show that the drug is not toxic at the doses that exert biological effects in these preclinical models. These data warrant additional studies for the potential use of VGX-1027 in the clinical setting.

A potent immunomodulatory compound, (S,R)-3-Phenyl-4,5-dihydro-5-isoxazole acetic acid, prevents spontaneous and accelerated forms of autoimmune diabetes in NOD mice and inhibits the immunoinflammatory diabetes induced by multiple low doses of streptozotocin in CBA/H mice

(S,R)-3-Phenyl-4,5-dihydro-5-isoxasole acetic acid (VGX-1027) is an isoxazole compound that exhibits various immunomodulatory properties. The capacity of VGX-1027 to prevent interleukin (IL)-1beta plus interferon-gamma-induced pancreatic islet death in vitro prompted us to evaluate its effects on the development of autoimmune diabetes in preclinical models of human type 1 diabetes mellitus (T1D). Administration of VGX-1027 to NOD mice with spontaneous or accelerated forms of diabetes induced either by injection of cyclophosphamide or by transfer of spleen cells from acutely diabetic syngeneic donors markedly reduced the cumulative incidence of diabetes and insulitis. In addition, VGX-1027 given either i.p. or p.o. to CBA/H mice made diabetic with multiple low doses of streptozotocin successfully counteracted the development of destructive insulitis and hyperglycemia. The animals receiving VGX-1027 exhibited reduced production of the proinflammatory mediators tumor necrosis factor-alpha, IL-1beta, macrophage migration inhibitory factor, and inducible nitric-oxide synthase-mediated nitric oxide generation in both pancreatic islets and peripheral compartments. These results indicate that VGX-1027 probably exerts its antidiabetogenic effects by limiting cytokine-mediated immunoinflammatory events, leading to inflammation and destruction of pancreatic islets. VGX-1027 seems worthy of being considered as a candidate drug in the development of new therapeutic strategies for the prevention and early treatment of T1D.

Neutralization of macrophage migration inhibitory factor—novel approach for the treatment of immunoinflammatory disorders

Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine that plays an important role in the pathogenesis of numerous inflammatory and autoimmune disorders. As such, it is an attractive therapeutic target for the treatment of these disorders. Several groups of possible MIF inhibitors have so far been identified, including anti-MIF antibodies, small chemical compounds and plant-derived inhibitors. This review presents current understanding of the effects of MIF neutralization in a number of experimental animal models of inflammatory and autoimmune diseases and discusses the potential problems in translating this kind of therapy into human subjects.