Background The formation of the NLRP3 inflammasome in the heart during AMI amplifies the inflammatory response and mediates further damage. Glyburide has NLRP3-inhibitory activity in vitro, but requires very high doses in vivo, associated with hypoglycemia. The aim of this study was to measure the effects on the NLRP3 inflammasome of 16673-34-0, an intermediate substrate free of the cyclohexylurea moiety, involved in insulin release. Methods and Results We synthetized 16673-34-0 (5-Chloro-2-methoxy-N-[2-(4-sulfamoylphenyl)ethyl]benzamide) that displayed no effect on glucose metabolism. HL-1 cardiomyocytes were treated with LPS+ATP to induce the formation of the NLRP3 inflammasome measured as increased caspase-1 activity and cell death, and 16673-34-0 prevented such effects. 16673-34-0 was well tolerated with no effects on the glucose levels in vivo. Treatment with 16673-34-0 in a model of AMI due to ischemia+reperfusion significantly inhibited the activity of inflammasome (caspase-1) in the heart by 90% (P<0.01) and reduced infarct size, measured at pathology (by >40%, P<0.01) and with troponin I levels (by >70%, P<0.01). Conclusions The small molecule 16673-34-0, an intermediate substrate in the glyburide synthesis free of the cyclohexylurea moiety, inhibits the formation of the NLRP3 inflammasome in cardiomyocytes and limits the infarct size following myocardial ischemia/reperfusion in the mouse, without affecting glucose metabolism.

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Background Sterile inflammation resulting from myocardial injury activates the NLRP3 inflammasome and amplifies the inflammatory response mediating further damage. Methods We used two experimental models of ischemic injury (acute myocardial infarction [AMI] with and without reperfusion) and a model of non-ischemic injury due to doxorubicin 10 mg/Kg, to determine whether the NLRP3 inflammasome preserved cardiac function after injury. Results Treatment with the NLRP3 inflammasome inhibitor in the reperfused AMI model caused a significant reduction in infarct size measured at pathology or as serum cardiac troponin I level (−56% and −82% respectively, both p<0.001), and preserved LV fractional shortening (LVFS, 31±2 vs vehicle 26±1%, p=0.003). In the non-reperfused AMI model treatment with the NLRP3 inhibitor significantly limited LV systolic dysfunction at 7 days (LVFS of 20±2 vs 14±1%, p=0.002), without a significant effect on infarct size. In the DOX model, a significant increase in myocardial interstitial fibrosis and a decline in systolic function were seen in vehicle-treated mice, whereas treatment with the NLRP3 inhibitor significantly reduced fibrosis (−80%, p=0.001) and preserved systolic function (LVFS 35±2 vs vehicle 27±2%, p=0.017). Conclusion Pharmacological inhibition of the NLRP3 inflammasome limits cell death and LV systolic dysfunction following ischemic and non-ischemic injury in the mouse.

The activation of the NLRP3 inflammasome signaling pathway plays an important role in the neuroinflammation in Alzheimer’s disease (AD). In this study, we investigated the effects of JC-124, a rationally designed NLRP3 inflammasome inhibitor, on AD-related deficits in CRND8 APP transgenic mice (TgCRND8). We first demonstrated increased formation and activation of NLRP3 inflammasome in TgCRND8 mice compared to non-transgenic littermate controls, which was inhibited by the treatment with JC-124. Importantly, JC-124 treatment led to decreased levels of Aβ deposition and decreased levels of soluble and insoluble Aβ1–42 in the brain of CRND8 mice which was accompanied by reduced β-cleavage of APP, reduced activation of microglia but enhanced astrocytosis. Oxidative stress was decreased and synaptophysin was increased in the CRND8 mice after JC-124 treatment, demonstrating a neuroprotective effect. Overall, these data demonstrated beneficial effects of JC-124 as a specific NLRP3 inflammasome inhibitor in AD mouse model and supported the further development of NLRP3 inflammasome inhibitors as a viable option for AD therapeutics.

In our effort to develop effective neuroprotectants as potential treatments for Alzheimer's disease (AD), hybrid compounds of curcumin and melatonin, two natural products that have been extensively studied in various AD models, were designed, synthesized, and biologically characterized. A lead hybrid compound (7) was discovered to show significant neuroprotection with nanomolar potency (EC50 = 27.60 ± 9.4 nM) in MC65 cells, a cellular AD model. Multiple in vitro assay results established that 7 exhibited moderate inhibitory effects on the production of amyloid-β oligomers (AβOs) in MC65 cells, but not on the aggregation of Aβ species. It also exhibited significant antioxidative properties. Further mechanistic studies demonstrated that 7's antioxidant effects correlate well with its neuroprotective potency for MC65 cells, and these effects might be due to its interference with the interactions of AβOs within the mitochondria of MC65 cells. Furthermore, 7 was confirmed to cross the blood-brain barrier (BBB) and deliver a sufficient amount to brain tissue after oral administration. Collectively, these results strongly support the hybridization approach as an efficient strategy to help identify novel scaffolds with a desired pharmacology, and strongly encourage further optimization of 7 to develop more potent neuroprotectants for AD.

In our efforts to develop novel small-molecule inhibitors for the NOD-like receptor family pyrin-domain-containing 3 (NLRP3) inflammasome as potential disease-modifying agents to treat neurological disorders including multiple sclerosis (MS), a hydroxyl sulfonamide analogue JC-171 has been rationally designed and biologically characterized both in vitro and in vivo. Our studies established that JC-171 dose dependently inhibited LPS/ATP-induced interleukin-1β (IL-1β) release from J774A.1 macrophages with an IC50 of 8.45 ± 1.56 μM. Selective inhibition of the NLRP3 inflammasome induced IL-1β release by this compound was also confirmed using mouse bone-marrow-derived macrophages and LPS-challenged mice in vivo. Furthermore, immunoprecipitation study revealed that JC-171 interfered with NLRP3/ASC interaction induced by LPS/ATP stimulation. More importantly, JC-171 treatment delayed the progression and reduced the severity of experimental autoimmune encephalomyelitis (EAE), a mouse model of MS, in both prophylactic and therapeutic settings. This coincided with blocking of IL-1β production and a pathogenic Th17 response. Collectively, these results suggest that JC-171 is a selective NLRP3 inflammasome inhibitor with biological activity in vivo, thus strongly encouraging further development of this lead compound as a potential therapeutic agent for human MS.

A recently developed bivalent ligand BMAOI 14 (7) has been evaluated for its capability to label and detect aggregated β-amyloid (Aβ) peptide as a fluorescent probe. This probe contains curcumin as the Aβ recognition moiety and cholesterol as an anchorage to the neuronal cell membrane/lipid rafts. The results demonstrate that 7 binds to the monomers, oligomers as well as fibrils of Aβ42 with low micromolar to submicromolar binding affinities. This chemical probe also has many of the required optical properties for use in imaging and can rapidly cross the blood-brain barrier (BBB) in vivo. Furthermore, 7 specifically binds to Aβ plaques in both AD human patients and APP transgenic mouse brain tissues. Collectively, these results suggest that 7 is a strong candidate as an Aβ-imaging agent and encourage further optimization of 7 as a new lead to develop the next generation of Aβ-imaging probes.

In an effort to combat the multifaceted nature of Alzheimer’s disease (AD) progression, a series of multifunctional, bivalent compounds containing curcumin and diosgenin were designed, synthesized, and biologically characterized. Screening results in MC65 neuroblastoma cells established that compound 38 with a spacer length of 17 atoms exhibited the highest protective potency with an EC50 of 111.7 ± 9.0 nM. A reduction in protective activity was observed as spacer length was increased up to 28 atoms and there is a clear structural preference for attachment to the methylene carbon between the two carbonyl moieties of curcumin. Further study suggested that antioxidative ability and inhibitory effects on amyloid-β oligomer (AβO) formation may contribute to the neuroprotective outcomes. Additionally, compound 38 was found to bind directly to Aβ, similar to curcumin, but did not form complexes with the common biometals Cu, Fe, and Zn. Altogether, these results give strong evidence to support the bivalent design strategy in developing novel compounds with multifunctional ability for the treatment of AD.