Neutrophil Migration During Liver Injury Is Under Nucleotide-Binding Oligomerization Domain 1 Control

Background & Aims: A more complete understanding of the mechanisms involved in pathogen-associated molecular pattern signaling is crucial in the setting of liver injury. In intestinal diseases, nucleotide-binding oligomerization domain 1 (NOD1), a receptor for bacteria, appears to regulate cross-talk between innate and adaptive immunity, involving polymorphonuclear neutrophils (PMNs). Our aim was to explore the role of NOD1 in PMN-induced liver injury. Methods: Nod1+/+ and Nod1-/- mice were challenged with carbon tetrachloride (CCl4). Migration and phagocytosis of Nod1+/+ and Nod1-/- PMN were studied in vivo and ex vivo. We evaluated main inflammatory pathways in PMNs by Western blot and CD11b expression using fluorescence-activated cell sorting. Mice were submitted to liver ischemia/reperfusion. Results: After CCl4 exposure, livers of Nod1-/- mice had more than 50% less PMN infiltration within necrotic areas than those of Nod1+/+. PMNs isolated from Nod1-/- mice displayed a 90% decrease in migration capacity compared with Nod1+/+ PMNs, whereas FK 565, a potent NOD1 ligand, increased PMN migration. Upon FK 565 stimulation, mitogen-activated protein kinase and nuclear factor ?B were activated in Nod1+/+ PMNs, but less so in Nod1-/- PMNs. Expression of CD11b on the Nod1-/- PMN was decreased compared with Nod1+/+. The phagocytic capacity of Nod1-/- PMNs was decreased by more than 50% compared with Nod1+/+. In an ischemia/reperfusion model of PMN-induced liver injury, FK 565 increased lesions, whereas Nod1-/- mice were protected. Conclusions: The identification of NOD1 as a modulator of PMN function and migration in the liver suggests that this receptor may represent a new therapeutic target in PMN-dependent liver diseases. 2010 AGA Institute.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

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