Michael Todorovic

Low-Dose Curcumin Stimulates Proliferation, Migration and Phagocytic Activity of Olfactory Ensheathing Cells

One of the promising strategies for neural repair therapies is the transplantation of olfactory ensheathing cells (OECs) which are the glial cells of the olfactory system. We evaluated the effects of curcumin on the behaviour of mouse OECs to determine if it could be of use to further enhance the therapeutic potential of OECs. Curcumin, a natural polyphenol compound found in the spice turmeric, is known for its anti-cancer properties at doses over 10 µM, and often at 50 µM, and it exerts its effects on cancer cells in part by activation of MAP kinases. In contrast, we found that low-dose curcumin (0.5 µM) applied to OECs strikingly modulated the dynamic morphology, increased the rate of migration by up to 4-fold, and promoted significant proliferation of the OECs. Most dramatically, low-dose curcumin stimulated a 10-fold increase in the phagocytic activity of OECs. All of these potently stimulated behavioural characteristics of OECs are favourable for neural repair therapies. Importantly, low-dose curcumin gave a transient activation of p38 kinases, which is in contrast to the high dose curcumin effects on cancer cells in which these MAP kinases tend to undergo prolonged activation. Low-dose curcumin mediated effects on OECs demonstrate cell-type specific stimulation of p38 and ERK kinases. These results constitute the first evidence that low-dose curcumin can modulate the behaviour of olfactory glia into a phenotype potentially more favourable for neural repair and thereby improve the therapeutic use of OECs for neural repair therapies.

Comprehensive assessment of genetic sequence variants in the antioxidant 'master regulator' Nrf2 in idiopathic parkinson's disease

Parkinson’s disease (PD) is a complex neurodegenerative disorder influenced by a combination of genetic and environmental factors. The molecular mechanisms that underlie PD are unknown; however, oxidative stress and impairment of antioxidant defence mechanisms have been implicated as major contributors to disease pathogenesis. Previously, we have reported a PD patient-derived cellular model generated from biopsies of the olfactory mucosa, termed hONS cells, in which the NRF2-mediated antioxidant response pathway genes were among the most differentially-expressed. To date, few studies have examined the role of the NRF2 encoding gene, NFE2L2, and PD. In this study, we comprehensibly assessed whether rare and common NFE2L2 genetic variations modify susceptibility to PD using a large Australian case-control sample (PD=1338, controls=1379). We employed a haplotype-tagging approach that identified an association with the tagging SNP rs2364725 and PD (OR = 0.849 (0.760-0.948), P = 0.004). Further genetic screening in hONS cell lines produced no obvious pathogenic variants in the coding regions of NFE2L2. Finally, we investigated the relationship between xenobiotic exposures and NRF2 function, through gene-environment interactions, between NFE2L2 SNPs and smoking or pesticide exposure. Our results demonstrated a significant interaction between rs2706110 and pesticide exposure (OR = 0.597 (0.393-0.900), P = 0.014). In addition, we were able to identify some age-at-onset modifying SNPs and replicate an ‘early-onset’ haplotype that contains a previously identified ‘functional promoter’ SNP (rs6721961). Our results suggest a role of NFE2L2 genetic variants in modifying PD susceptibility and onset. Our findings also support the utility of testing gene-environment interactions in genetic studies of PD.

Nrf2: a modulator of Parkinson’s disease?

Parkinson’s disease (PD) is a complex multifactorial disorder that has been associated with the processes of oxidative stress. In the absence of curative therapies, modification of the neurodegenerative process—including the manipulation of endogenous antioxidant pathways—is the focus of intensive research. Recently, genetic and pharmacological accretion of the transcription factor, and phase II antioxidant ‘master regulator’ Nrf2, has shown to demonstrably mitigate the toxic neuronal effects of parkinsonian agents such as MPP+, rotenone, and hydrogen peroxide in vitro and in vivo. Furthermore, baseline genetic variability in Nrf2-dependant pathways may promote neuronal susceptibility to exogenous agents and correlate with PD onset within certain populations. While contemporary evidence directly implicating Nrf2 in the pathogenesis of PD is not conclusive and likely contingent upon the evaluation of complex interacting factors—including genetic variation and a history of environmental exposures—it remains a promising target for therapeutic benefit in the modulation of oxidative stress.

Rotenone Susceptibility Phenotype in Olfactory Derived Patient Cells as a Model of Idiopathic Parkinson’s Disease

Parkinson’s disease is a complex age-related neurodegenerative disorder. Approximately 90% of Parkinson’s disease cases are idiopathic, of unknown origin. The aetiology of Parkinson’s disease is not fully understood but increasing evidence implies a failure in fundamental cellular processes including mitochondrial dysfunction and increased oxidative stress. To dissect the cellular events underlying idiopathic Parkinson’s disease, we use primary cell lines established from the olfactory mucosa of Parkinson’s disease patients. Previous metabolic and transcriptomic analyses identified deficiencies in stress response pathways in patient-derived cell lines. The aim of this study was to investigate whether these deficiencies manifested as increased susceptibility, as measured by cell viability, to a range of extrinsic stressors. We identified that patient-derived cells are more sensitive to mitochondrial complex I inhibition and hydrogen peroxide induced oxidative stress, than controls. Exposure to low levels (50 nM) of rotenone led to increased apoptosis in patient-derived cells. We identified an endogenous deficit in mitochondrial complex I in patient-derived cells, but this did not directly correlate with rotenone-sensitivity. We further characterized the sensitivity to rotenone and identified that it was partly associated with heat shock protein 27 levels. Finally, transcriptomic analysis following rotenone exposure revealed that patient-derived cells express a diminished response to rotenone-induced stress compared with cells from healthy controls. Our cellular model of idiopathic Parkinson’s disease displays a clear susceptibility phenotype to mitochondrial stress. The determination of molecular mechanisms underpinning this susceptibility may lead to the identification of biomarkers for either disease onset or progression.

Developing and evaluating effective bioscience learning activities for nursing students

Effective engagement of nursing students in the study of biosciences remains a challenge for many tertiary institutes. In this study we attempted to implement and then evaluate a simple hands-on intervention, consisting of a series of hands-on games and puzzles, to increase nursing student engagement with core concepts and anatomical learning involved in clinical anatomy and physiology. The study used a quazi-experimental longitudinal before and after design, to explore the effect of a learning intervention on student performance. Set across three different campuses of the same University, it included 1320 first year undergraduate nursing students from 2013 to 2014 who were studying Anatomy and Physiology. Students were exposed to the interventions or not, and concomitant academic performance, weekly quiz scores, performance in fortnightly worksheets and, across the semester, exam performance were compared. The results show that while the intervention appeared to increase academic performance in students on one campus (2013) compared to the other two, this difference was not sustained into 2014 when a bigger cohort was examined. Despite significant subjective student satisfaction and enthusiasm about these learning and teaching interventions, the data does not support the capacity of these activities to enhance student academic performance. Tertiary entrance scores, being a non-native English speakers and socio-economic status all had a bigger impact on student performance than engagement with fun anatomy and physiology activities.

Lack of reproducibility in re-evaluating associations between GCH1 polymorphisms and Parkinson's disease and isolated dystonia in an Australian case–control group

AN US CR IP T AC CE PT ED ACCEPTED MANUSCRIPT Lack of reproducability in re-evaluating associations between GCH1 polymorphisms and Parkinson’s disease and isolated dystonia in an Australian case-control group Jeremy R. B. Newman , Michael Todorovic, Peter A. Silburn , Greg T. Sutherland , George D. Mellick 1. Eskitis Institute for Drug Discovery, Griffith University, Nathan, Queensland, Australia 2. Department of Neurology, Princess Alexandra Hospital, Woolloongabba, Queensland, Australia 3. Department of Neurology, Royal Brisbane and Women’s Hospital, Herston, Queensland, Australia 4. University of Queensland Centre for Clinical Research, School of Medicine, Queensland, Royal Brisbane and Women’s Hospital, Herston, Australia 5. Discipline of Pathology, Sydney Medical School, University of Sydney, Camperdown, New South Wales, Australia

Rare POLG1 CAG variants do not influence Parkinson's disease or polymerase gamma function

A recent meta-analysis suggested that rare CAG repeat variants in the gene that encodes polymerase gamma (POLG1) predispose individuals to develop Parkinsons disease (PD); alternative alleles were proposed to increase risk by 27%. In the current case-control study of 2255 Australians, we observed no statistical association between individuals possessing rare CAG repeat genotypes and PD (p=0.178); a subsequent meta-analysis of 2852 PD cases and 2833 controls was also non-significant (OR=1.085, p=0.124). Moreover, mitochondrial DNA synthesis (p=0.427) or Complex I activity (p=0.639) were not different in cells derived from individuals with different POLG1 genotypes. These data provide no evidence to suggest CAG repeat length in POLG1 affects PD susceptibility.

Olfactory Ensheathing Cells for Spinal Cord Injury: Sniffing Out the Issues

Olfactory ensheathing cells (OECs) are glia reported to sustain the continuous axon extension and successful topographic targeting of the olfactory receptor neurons responsible for the sense of smell (olfaction). Due to this distinctive property, OECs have been trialed in human cell transplant therapies to assist in the repair of central nervous system injuries, particularly those of the spinal cord. Though many studies have reported neurological improvement, the therapy remains inconsistent and requires further improvement. Much of this variability stems from differing olfactory cell populations prior to transplantation into the injury site. While some studies have used purified cells, others have used unpurified transplants. Although both preparations have merits and faults, the latter increases the variability between transplants received by recipients. Without a robust purification procedure in OEC transplantation therapies, the full potential of OECs for spinal cord injury may not be realised.

Enhancing the Therapeutic Potential of Olfactory Ensheathing Cells in Spinal Cord Repair Using Neurotrophins

Autologous olfactory ensheathing cell (OEC) transplantation is a promising therapy for spinal cord injury; however, the efficacy varies between trials in both animals and humans. The main reason for this variability is that the purity and phenotype of the transplanted cells differs between studies. OECs are susceptible to modulation with neurotrophic factors, and thus, neurotrophins can be used to manipulate the transplanted cells into an optimal, consistent phenotype. OEC transplantation can be divided into 3 phases: (1) cell preparation, (2) cell administration, and (3) continuous support to the transplanted cells in situ. The ideal behaviour of OECs differs between these 3 phases; in the cell preparation phase, rapid cell expansion is desirable to decrease the time between damage and transplantation. In the cell administration phase, OEC survival and integration at the injury site, in particular migration into the glial scar, are the most critical factors, along with OEC-mediated phagocytosis of cellular debris. Finally, continuous support needs to be provided to the transplantation site to promote survival of both transplanted cells and endogenous cells within injury site and to promote long-term integration of the transplanted cells and angiogenesis. In this review, we define the 3 phases of OEC transplantation into the injured spinal cord and the optimal cell behaviors required for each phase. Optimising functional outcomes of OEC transplantation can be achieved by modulation of cell behaviours with neurotrophins. We identify the key growth factors that exhibit the strongest potential for optimizing the OEC phenotype required for each phase.

Nrf2 and Parkinson’s Disease

Parkinson’s disease (PD) results from a complex interaction of environmental and genetic influences on a background of aging. Regardless of etiology, significant clinical advances rely on identifying the common biological pathways that underpin neuronal degeneration. Oxidative stress is consistently reported as a hallmark feature of PD. Recently, it has been demonstrated that Nrf2 modulation can protect neurons from parkinsonian agents and, in some instances, reverse motor symptoms of animal models. Furthermore, baseline aberrations of Nrf2 and its associated pathway have been reported in PD patients, and genetic variability—within and around the Nrf2 gene— may modify PD susceptibility and onset. Overall, Nrf2 dysregulation has been tentatively implicated in the pathogenesis of PD and may prove to be an effective therapeutic target.