Leucine-Rich Repeat Kinase 2 (Lrrk2) Deficiency Diminishes the Development of Experimental Autoimmune Uveitis (EAU) and the Adaptive Immune Response

Background

Mutations in LRRK2 are related to certain forms of Parkinson’s disease and, possibly, to the pathogenesis of Crohn’s disease. In both these diseases inflammatory processes participate in the pathogenic process. LRRK2 is expressed in lymphoid cells and, interestingly, Lrrk2 (-/-) mice were reported to develop more severe experimental colitis than their wild type (WT) controls. Here, we examined the possible involvement of LRRK2 in the pathogenesis of experimental autoimmune uveitis (EAU), an animal model for human uveitis, by testing Lrrk2 (-/-) mice for their capacity to develop this experimental eye disease and related immune responses.

Methods

Lrrk2 (-/-) mice and their WT controls (C57Bl/6) were immunized with interphotoreceptor retinoid-binding protein (IRBP) and compared for their development of EAU, delayed type hypersensitivity (DTH) by skin tests, production of cytokines in culture, and expression of interferon (IFN)-γ, interleukin (IL)-17 and FoxP3 by spleen cells, using flow cytometry. Peritoneal macrophages were examined for their production of cytokines/chemokines in culture following stimulation with LPS or the oligodeoxynucleotide CpG. The Lrrk2 (-/-) and WT mice were also compared for their response to bovine serum albumin (BSA).

Results

The Lrrk2 (-/-) mice developed lower levels of EAU, DTH responses and cytokine production by lymphocytes than did their WT controls. Intracellular expression of IFN-γ and IL-17, by spleen cells, and secretion of cytokines/chemokines by activated peritoneal macrophages of Lrrk2 (-/-) mice trended toward diminished levels, although variabilities were noted. The expression levels of FoxP3 by Lrrk2 (-/-) spleen cells, however, were similar to those seen in WT controls. Consistent with their low response to IRBP, Lrrk2 (-/-) mice responded to BSA less vigorously than their WT controls.

Conclusions

Lrrk2 deficiency in mice diminished the development of EAU and the related adaptive immune responses to IRBP as compared to the WT controls.     

Adaptation of a South American malaria vector to laboratory colonization suggests faster-male evolution for mating ability

Background  

Anopheles (Nyssorhynchus) albitarsis (Diptera: Culicidae) is one of the very few South American mosquito vectors of malaria successfully colonized in the laboratory. These vectors are very hard to breed because they rarely mate in artificial conditions. A few years ago a free-mating laboratory colony of An. albitarsis sensu stricto was established after about 30 generations of artificial-mating. To begin to understand the process of adaptation of these malaria vectors to the laboratory we have compared the insemination rates of colony mosquitoes to those from the original population in both artificial and free-mating crosses. We also carried out crossing experiments between the two types of mosquitoes for a preliminary analysis of the genetic basis of such adaptation.     

Reconstructing Indian-Australian phylogenetic link

Background  

An early dispersal of biologically and behaviorally modern humans from their African origins to Australia, by at least 45 thousand years via southern Asia has been suggested by studies based on morphology, archaeology and genetics. However, mtDNA lineages sampled so far from south Asia, eastern Asia and Australasia show non-overlapping distributions of haplogroups within pan Eurasian M and N macrohaplogroups. Likewise, support from the archaeology is still ambiguous.     

The Association of the Vanin-1 N131S Variant with Blood Pressure Is Mediated by Endoplasmic Reticulum-Associated Degradation and Loss of Function

High blood pressure (BP) is the most common cardiovascular risk factor worldwide and a major contributor to heart disease and stroke. We previously discovered a BP-associated missense SNP (single nucleotide polymorphism)–rs2272996–in the gene encoding vanin-1, a glycosylphosphatidylinositol (GPI)-anchored membrane pantetheinase. In the present study, we first replicated the association of rs2272996 and BP traits with a total sample size of nearly 30,000 individuals from the Continental Origins and Genetic Epidemiology Network (COGENT) of African Americans (P = 0.01). This association was further validated using patient plasma samples; we observed that the N131S mutation is associated with significantly lower plasma vanin-1 protein levels. We observed that the N131S vanin-1 is subjected to rapid endoplasmic reticulum-associated degradation (ERAD) as the underlying mechanism for its reduction. Using HEK293 cells stably expressing vanin-1 variants, we showed that N131S vanin-1 was degraded significantly faster than wild type (WT) vanin-1. Consequently, there were only minimal quantities of variant vanin-1 present on the plasma membrane and greatly reduced pantetheinase activity. Application of MG-132, a proteasome inhibitor, resulted in accumulation of ubiquitinated variant protein. A further experiment demonstrated that atenolol and diltiazem, two current drugs for treating hypertension, reduce the vanin-1 protein level. Our study provides strong biological evidence for the association of the identified SNP with BP and suggests that vanin-1 misfolding and degradation are the underlying molecular mechanism.     

Ultrastructural localization of amiloride-sensitive sodium channels and Na+,K(+)-ATPase in the rat's olfactory epithelial surface

Several studies have indicated that olfactory responses are impeded by amiloride. Therefore, it was of interest to see whether, and if so which, olfactory epithelial cellular compartments have amiloride- sensitive structures. Using ultrastructural methods that involved rapid freezing, freeze-substitution and low temperature embedding of olfactory epithelia, this study shows that, in the rat, this tissue is immunoreactive to antibodies against amiloride sensitive Na(+)- channels. However, microvilli of olfactory supporting cells, as opposed to receptor cilia, contained most of the immunoreactive sites. Apices from which the microvilli sprout and receptor cell dendritic knobs had much less if any of the amiloride-antibody binding sites. Using a direct ligand-binding cytochemical method, this study also confirms earlier ones that showed that olfactory receptor cell cilia have Na+, K(+)-ATPase. It is proposed that supporting cell microvilli and the receptor cilia themselves have mechanisms, different but likely complementary, that participate in regulating the salt concentration around the receptor cell cilia. In this way, both structures help to provide the ambient mucous environment for receptor cells to function properly. This regulation of the salt concentration of an ambient fluid environment is a function that the olfactory epithelium shares with cells of transporting epithelia, such as those of kidney.      

The effects of lead upon collagen synthesis and proline hydroxylation in the Swiss mouse 3T6 fibroblast.

The effects of lead upon collagen synthesis and proline hydroxylation were examined in the Swiss mouse 3T6 fibroblast. The results indicate that lead reduces proline hydroxylation in stationary phase cultures of 3T6 cells, resulting in increased cellular retention of unhydroxylated procollagen. Inhibition of proline hydroxylation by lead was prevented by increasing the extracellular $\text{Fe}{}^{\mathrm{2+}}\text{Pb}{}^{\mathrm{2+}}$ molar ratio. Interference by lead in the hydroxylation of proline in logarithmic phase cultures of 3T6 cells resulted in increases in the 0.5 n HClO₄ soluble/insoluble hydroxyproline ratio. This was attributed to an increase in the rate of breakdown of lead-induced unhydroxylated procollagen. Kinetic analysis of the lead-iron interaction with proline hydroxylase suggests that the mechanism is competitive.