Pramipexole attenuates neuronal injury in Parkinson's disease by targeting miR-96 to activate BNIP3-mediated mitophagy.

BACKGROUND: Parkinson's disease is a common neurodegenerative problem. Pramipexole (PPX) plays protective role in Parkinson's disease. Nevertheless, the mechanism of PPX in Parkinson's disease-like neuronal injury is largely uncertain. METHODS: 1-methyl-4-phenylpyridinium (MPP+)-stimulated neuronal cells and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mice were used as the model of Parkinson's disease. MPP+-induced neuronal injury was assessed via cell viability, lactic dehydrogenase (LDH) release and apoptosis. microRNA-96 (miR-96) and BCL2/adenovirus E1B 19 kDa interacting protein 3 (BNIP3) abundances were examined by quantitative reverse transcription polymerase chain reaction (qRT-PCR) or Western blotting. Mitophagy was tested by Western blotting and immunofluorescence staining. MPTP-induced neuronal injury in mice was investigated via behavioral tests and TUNEL. RESULTS: PPX alleviated MPP+-induced neuronal injury via increasing cell viability and decreasing LDH release and apoptosis. PPX reversed MPP+-induced miR-96 expression and inhibition of mitophagy. miR-96 overexpression or BNIP3 interference weakened the suppressive role of PPX in MPP+-induced neuronal injury. miR-96 targeted BNIP3 to inhibit PTEN-induced putative kinase 1 (PINK1)/Parkin signals-mediated mitophagy. miR-96 overexpression promoted MPP+-induced neuronal injury via decreasing BNIP3. PPX weakened MPTP-induced neuronal injury in mice via regulating miR-96/BNIP3-mediated mitophagy. CONCLUSION: PPX mitigated neuronal injury in MPP+-induced cells and MPTP-induced mice by activating BNIP3-mediated mitophagy via directly decreasing miR-96.

Dexpramipexole as an oral steroid-sparing agent in hypereosinophilic syndromes.

Hypereosinophilic syndromes (HESs) are a heterogeneous group of disorders characterized by peripheral eosinophilia and eosinophil-related end organ damage. Whereas most patients respond to glucocorticoid (GC) therapy, high doses are often necessary, and side effects are common. Dexpramipexole (KNS-760704), an orally bioavailable synthetic aminobenzothiazole, showed an excellent safety profile and was coincidentally noted to significantly decrease absolute eosinophil counts (AECs) in a phase 3 trial for amyotrophic lateral sclerosis. This proof-of-concept study was designed to evaluate dexpramipexole (150 mg orally twice daily) as a GC-sparing agent in HESs. Dual primary end points were (1) the proportion of subjects with ≥50% decrease in the minimum effective GC dose (MED) to maintain AEC <1000/µL and control clinical symptoms, and (2) the MED after 12 weeks of dexpramipexole (MEDD) as a percentage of the MED at week 0. Out of 10 subjects, 40% (95% confidence interval [CI], 12%, 74%) achieved a ≥50% reduction in MED, and the MEDD/MED ratio was significantly <100% (median, 66%; 95% CI, 6%, 98%; P = .03). All adverse events were self-limited, and none led to drug discontinuation. Affected tissue biopsy samples in 2 subjects showed normalization of pathology and depletion of eosinophils on dexpramipexole. Bone marrow biopsy samples after 12 weeks of dexpramipexole showed selective absence of mature eosinophils in responders. Dexpramipexole appears promising as a GC-sparing agent without apparent toxicity in a subset of subjects with GC-responsive HESs. Although the exact mechanism of action is unknown, preliminary data suggest that dexpramipexole may affect eosinophil maturation in the bone marrow. This study was registered at www.clinicaltrials.gov as #NCT02101138.