Immunopharmacology and inflammationNovel inhibitors of macrophage migration inhibitory factor prevent cytokine-induced beta cell death
Introduction
Type 1diabetes is an autoimmune disease characterized by a local inflammatory reaction in and around the pancreatic islets, followed by progressive destruction of insulin producing beta cells that leads to hyperglycemia. Until now, a number of pathological stimuli have been identified to induce beta cell apoptosis: reactive oxidative and nitrogen species, perforins and granzymes, Fas ligand and most importantly pro-inflammatory cytokines such as interferon-γ (IFN-γ), interleukin-1β (IL-1β) and tumor necrosis factor α (TNF-α) (Padgett et al., 2013). Type 2 diabetes is characterized by insulin resistance in peripheral tissues that manifests as hyperglycemia when beta cells fail to regulate insulin production due to their demise mediated by elevated nutrients and cytokines. All mentioned cytotoxic stimuli that contribute to beta cell loss identified in type 1 and type 2 diabetes converge on mitochondria to lead the beta cell to apoptosis (Szabadkai and Duchen, 2009). Recently, another cytokine, macrophage migration inhibitory factor (MIF) has been identified as an important factor for beta cell survival and MIF inhibition plays a crucial role in blocking a mitochondria-mediated apoptotic process. MIF absence or blockade ensures protection of beta cells from exposure to either pro-inflammatory cytokines (Stojanovic et al., 2012a) or elevated nutrients (palmitic acid or glucose) in vitro (Stojanovic et al., 2012b).
in vivo experiments proved that MIF is crucial for development of type 1 diabetes (Bojunga et al., 2003) and that MIF inhibition by neutralizing antibodies (Cvetkovic et al., 2005) or complete MIF absence (MIF knock-out) ameliorates initiation and/or progression of type 1 diabetes (Stosic-Grujicic et al., 2008). These data indicate that the inhibition of MIF could be exploited as a therapeutic strategy (Stosic-Grujicic et al., 2009, Greven et al., 2010). Having in mind that the usage of neutralizing antibodies for therapy could result in side-effects and is expensive, several pharmacologically designed MIF inhibitors have been synthetized and have shown promising results. One of the best characterized and also most well-known MIF inhibitors is (S,R)-3-(4-hydroxyphenyl)-4,5-dihydro-5-isoxazole acetic acid methyl ester (ISO-1) (reviewed in Al-Abed et al., 2011). It was shown that ISO-1 has beneficial effects in experimental colitis (Shah et al., 2008), experimental allergic neuritis (Nicoletti et al., 2005) and in endotoxemia (Al-Abed et al., 2005). In MIF׳s homotrimeric structure a hydrophobic pocket region formed between each adjacent subunit plays an important role in its biological function, as evidenced by the fact that ISO-1 binding of this region decreases downstream MIF signaling, MIF biological activities and clinical outcomes that are associated with MIF (Al-Abed et al., 2011).
Since we have previously shown that in vivo MIF inhibition by ISO-1 ameliorates streptozotocin induced type 1 diabetes development in C57BL/6 mice (Cvetkovic et al., 2005) and that in vitro ISO-1 protects insulinoma cells or pancreatic islets from pro-inflammatory cytokines (Stojanovic et al., 2008) the aim of this study was to compare the activity of two novel MIF inhibitors with ISO-1 and to investigate, in more detail, the mechanism of their action.
Section snippets
Materials and methods
Unless stated otherwise, all chemicals were from Sigma-Aldrich (St Louis, MO, USA) and all plastics used in the experiments were from Sardstedt (Numbrecht, Germany).
Novel MIF inhibitors K664-1 and K647-1 are potent inhibitors of MIF enzymatic activity
The concentration required to inhibit 50% of the control tautomerase activity (IC-50) was determined by established methods and compared for the two new compounds versus the established MIF inhibitor, ISO-1. The IC-50′s of K647-1 (0.41×0.01 μM) and K664-1 (0.11±0.03 μM) were approximately 40 and 160x more potent than ISO-1 (Table 1).
K664-1 and K647-1 inhibit the recognition of MIF
Interaction of ISO-1 with recombinant MIF in vitro down-regulates immunorecognition of MIF during ELISA (Hegde et al., 2012). Therefore, we first sought to
Discussion
In the present study, we demonstrate that the two newly synthetized compounds, K664-1 and K647-1, are potent inhibitors of MIF tautomerase activity and that they rescue beta cells from cytokine-driven apoptosis. This protection is provided at lower concentrations compared to ISO-1. The new MIF inhibitors likely operate through inhibition of BAX-mediated apoptosis, unlike ISO-1. However, all three inhibitors prevent caspase-3 activation and NO production.
MIF is an important regulator of
Acknowledgments
We would like to thank Melita Vidakovic, PhD, from the Institute for Biological Research “Sinisa Stankovic”, University of Belgrade, Belgrade, Serbia for the kind gift of RINm5f cell culture. This work was supported by Ministry of Education, Science and Technological Development, Republic of Serbia (Project no. 173013).
References (28)
- et al.
ISO-1 binding to the tautomerase active site of MIF inhibits its pro-inflammatory activity and increases survival in severe sepsis
J. Biol. Chem.
(2005) - et al.
Macrophage migration inhibitory factor and development of type-1 diabetes in non-obese diabetic mice
Cytokine
(2003) A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding
Anal. Biochem.
(1976)- et al.
Vitamin E is a MIF inhibitor
Biochem. Biophys. Res. Commun.
(2012) - et al.
The tautomerase active site of macrophage migration inhibitory factor is a potential target for discovery of novel anti-inflammatory agents
J. Biol. Chem.
(2002) Rapid colorimetric assay for cellular growth and survival:application to proliferation and cytotoxicity assays
J. Immunol. Methods
(1983)- et al.
Macrophage migration inhibitory factor (MIF) seems crucially involved in Guillain–Barré syndrome and experimental allergic neuritis
J. Neuroimmunol.
(2005) - et al.
MIF in autoimmunity and novel therapeutic approaches
Autoimmun. Rev.
(2009) - et al.
MIF as a disease target: ISO-1 as a proof-of-concept therapeutic
Future Med. Chem.
(2011) - et al.
Thyroxine is a potential endogenous antagonist of macrophage migration inhibitory factor (MIF) activity
Proc. Natl. Acad. Sci. U. S. A.
(2011)
Critical role of macrophage migration inhibitory factor activity in experimental autoimmune diabetes
Endocrinology
Inhibition of MIF bioactivity by rational design of pharmacological inhibitors of MIF tautomerase activity
J. Med. Chem.
A tautomerase-null macrophage migration-inhibitory factor (MIF) gene knock-in mouse model reveals that protein interactions and not enzymatic activity mediate MIF-dependent growth regulation
Mol. Cell. Biol.
Autoimmune diseases: MIF as a therapeutic target
Expert Opin. Ther. Targets
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2020, CytokineCitation Excerpt :This issue will be discussed further in the next section. Intriguingly, both genetic MIF deletion and MIF inhibition with different MIF inhibitors prevented cytokine-induced beta cell death through down-regulation of BAX or caspase 3-related pathways in vitro [61,62]. This means that in the circumstances of MIF overproduction (under the influence of cytokines or palmitic acid), MIF acquires detrimental influence on beta cells.
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2018, Drug Discovery TodayCitation Excerpt :Another study, reported for MIF inhibitor K664-1 (Table 2) with a pyrimidazole scaffold an IC50 of 0.16 μM in the MIF tautomerase assay [72]. This inhibitor provided protection to β cells from cytokine-triggered apoptosis in a mouse model, which demonstrates its potential for the prevention of diabetes progression [73]. In 2016, compound T-614 (also known as iguratimod) was found to selectively inhibit MIF in vitro and in vivo.
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2017, Metabolism: Clinical and ExperimentalCitation Excerpt :Additionally, MIF may act as a pro-apoptotic molecule in β-cells after exposure to any toxic insult. MIF triggers apoptosis via the mitochondria-related apoptotic pathway by decreasing the Bcl-2/Bax ratio, with subsequent cleavage of caspase 3 in pancreatic β-cells [47]. Consistent with these findings, the increased expression levels of Bax and cleaved caspase 3 in both animal and cell models were also observed in our study.
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2016, Journal of Biological Chemistry
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Authors equally contributed.