Lrrk2 alleles modulate inflammation during microbial infection of mice in a sex-dependent manner.

Variants in the leucine-rich repeat kinase-2 (LRRK2) gene are associated with Parkinson's disease, leprosy, and Crohn's disease, three disorders with inflammation as an important component. Because of its high expression in granulocytes and CD68-positive cells, LRRK2 may have a function in innate immunity. We tested this hypothesis in two ways. First, adult mice were intravenously inoculated with Salmonella typhimurium, resulting in sepsis. Second, newborn mouse pups were intranasally infected with reovirus (serotype 3 Dearing), which induced encephalitis. In both mouse models, wild-type Lrrk2 expression was protective and showed a sex effect, with female Lrrk2-deficient animals not controlling infection as well as males. Mice expressing Lrrk2 carrying the Parkinson's disease-linked p.G2019S mutation controlled infection better, with reduced bacterial growth and longer animal survival during sepsis. This gain-of-function effect conferred by the p.G2019S mutation was mediated by myeloid cells and was abolished in animals expressing a kinase-dead Lrrk2 variant, p.D1994S. Mouse pups with reovirus-induced encephalitis that expressed the p.G2019S Lrrk2 mutation showed increased mortality despite lower viral titers. The p.G2019S mutant Lrrk2 augmented immune cell chemotaxis and generated more reactive oxygen species during virulent infection. Reovirus-infected brains from mice expressing the p.G2019S mutant Lrrk2 contained higher concentrations of α-synuclein. Animals expressing one or two p.D1994S Lrrk2 alleles showed lower mortality from reovirus-induced encephalitis. Thus, Lrrk2 alleles may alter the course of microbial infections by modulating inflammation, and this may be dependent on the sex and genotype of the host as well as the type of pathogen.

Analysis of macroautophagy related proteins in G2019S LRRK2 Parkinson's disease brains with Lewy body pathology.

LRRK2, the gene encoding the multidomain kinase Leucine-Rich Repeat Kinase 2 (LRRK2), has been linked to familial and sporadic forms of Parkinson's disease (PD), as well as cancer, leprosy and Crohn's disease, establishing it as a target for discovery therapeutics. LRRK2 has been associated with a range of cellular processes, however its physiological and pathological functions remain unclear. The most prevalent LRRK2 mutations in PD have been shown to affect macroautophagy in various cellular models while a role in autophagy signalling has been recapitulated in vivo. Dysregulation of autophagy has been implicated in PD pathology, and this raises the possibility that differential autophagic activity is relevant to disease progression in PD patients carrying LRRK2 mutations. To examine the relevance of LRRK2 to the regulation of macroautophagy in a disease setting we examined the levels of autophagic markers in the basal ganglia of G2019S LRRK2 PD post-mortem tissue, in comparison to pathology-matched idiopathic PD (iPD), using immunoblotting (IB). Significantly lower levels of p62 and LAMP1 were observed in G2019S LRRK2 PD compared to iPD cases. Similarly, an increase in ULK1 was observed in iPD but was not reflected in G2019S LRRK2 PD cases. Furthermore, examination of p62 by immunohistochemistry (IH) recapitulated a distinct signature for G2019S PD. IH of LAMP1, LC3 and ULK1 broadly correlated with the IB results. Our data from a small but pathologically well-characterized cases highlights a divergence of G2019S PD carriers in terms of autophagic response in alpha-synuclein pathology affected brain regions compared to iPD.

Rifampicin protects PC12 cells against MPP+-induced apoptosis and inhibits the expression of an alpha-Synuclein multimer.

The potential cytoprotective effects of the anti-leprosy antibiotic rifampicin were investigated in rat pheochromocytoma (PC12) cells prior to intoxication with 1-Methyl-4-phenyl pyridinium (MPP(+)). MPP(+) induced both apoptotic and necrotic cell death, and increased the expression of a 57 kDa species of alpha-Synuclein. This species of alpha-Synuclein is larger than the monomer, and is therefore an oligomer or an aggregated form of the protein. Rifampicin significantly increased survival of these catecholaminergic cells in a concentration-dependent manner. The expression of the higher molecular mass alpha-Synuclein was increased by MPP(+) exposure, and its expression was inversely related to cell survival in the rifampicin-treated cells. Importantly, rifampicin suppressed apoptosis almost completely, without shifting the death cascade to necrosis, which is a problem that has been reported with caspase inhibitors of apoptosis (Hartmann, A., Troadec, J.D., Hunot, S., Kikly, K., Faucheux, B.A., Mouatt-Prigent, A., Ruberg, M. Agid, Y., Hirsch, E.C., 2001. Caspase-8 is an effector in apoptotic death of dopaminergic neurons in Parkinson's disease, but pathway inhibition results in neuronal necrosis. J. Neurosci. 21, 2247-2255). These results suggest that rifampicin improves survival of catecholamine- and alpha-Synuclein-containing cells, which degenerate in Parkinson's disease (PD), and thus may be therapeutic in this disease.