Dendritic cells from CD patients were also shown to exhibit increased LRRK2 levels infection (Zhang et al., 2015). needed for pathogenic LRRK2 mutations to induce a PD phenotype. With this review, we will discuss the link between LRRK2 and swelling and how this could play an active part in PD etiology. LRRK2 substrates NSC 319726 (Steger et al., 2016; Fujimoto et al., 2017; Liu et al., 2018; Rivero-Ros et al., 2019). These small GTPases are regulators of membrane trafficking and are also involved in cellular processes essential for immune cell activity such as phagocytosis, exocytosis, and antigen demonstration (examined in Prashar et al., 2017; Wallings and Tansey, 2019). This is good emerging evidence pointing to LRRK2 like a modulator of swelling through a role in immune cells both in the CNS and the periphery. Several studies possess reported the dysregulation of inflammatory events by LRRK2 Already in 2009 2009, Lin et al. (2009) reported an increase in microgliosis and astrogliosis in A53T SYN transgenic mice in the presence of LRRK2 G2019S. However, no effect of the G2019S mutation could be observed in microglia inside a different transgenic SYN model (Daher et al., 2012). In 2015, Daher et al. (2015) reported an increased activation of microglia in the SN of a G2019S LRRK2 transgenic rat after recombinant adeno-associated viral vector (rAAV)-mediated SYN overexpression. This increase in neuroinflammation was accompanied by a more pronounced neurodegeneration and could be abolished from the NSC 319726 inhibition of LRRK2 kinase activity. Recently, another study showed increased manifestation of CD68 in microglia from G2019S LRRK2 mice injected with recombinant SYN fibrils, as well as increased manifestation of pro-inflammatory markers such as IL-6, TNF and C1qa and astroglial markers like Vim, CD44 and Cxcl10 (Bieri et al., 2019). In addition, a physiological part for WT LRRK2 in neuroinflammation is definitely supported by studies using LRRK2 knock out (KO) models. Genetic ablation Mouse Monoclonal to GFP tag of LRRK2 was reported to protect against dopaminergic neurodegeneration induced by lipopolysaccharide (LPS), as well as against the neuroinflammation and neurodegeneration induced by rAAV-based overexpression of SYN (Daher et al., 2014). LRRK2 KO animals displayed a reduced number of CD68 and iNOS positive cells and reduced myeloid cell activation as demonstrated from the absence of a shift in morphology from ramified to amoeboid Iba1+-cells. The evidence that WT LRRK2 isn’t just involved in PD-related neuroinflammation is definitely underlined from the finding that suppressing LRRK2 activity or manifestation is also protecting against neuroinflammation after exposure to manganese (Chen et al., 2018) or HIV-1 Tat protein in an HIV-1 connected neurocognitive disorder (HAND) model (Puccini et al., 2015). Taken together, LRRK2 is considered as a pro-inflammatory agent in different neuroinflammatory animal models with increased LRRK2 kinase activity like a driver of swelling. LRRK2 in Immune Cells In order to understand the physiological and pathological function of LRRK2, it is essential to identify the cell types in which LRRK2 plays a major role. Microglia are the 1st barrier of the innate immune system in the brain. Therefore, most attempts to elucidate the function of LRRK2 in neuroinflammation have focused on this cell type. Reducing the manifestation or activity of LRRK2 in microglia was shown to reduce the levels of pro-inflammatory cytokines such as TNFa, IL6, IL-1b, or IL-10 (Kim et al., 2012; Moehle et al., 2012; Russo et al., 2015) as well as to enhance microglial motility induced by adenosine diphosphate (ADP) and fractalkine, characteristic of microglia inside a nonreactive state (Choi et al., 2015; Ma et al., 2016). Contrarily, mutations enhancing LRRK2 activity such as G2019S or R1441G were reported to shift cultured microglia to a more pro-inflammatory phenotype NSC 319726 (Gillardon et al., 2012; Caesar et al., 2014; Choi et al., 2015; Russo et al., 2018). In addition, elevated LRRK2 mRNA levels were found in human being and rodent microglia and protein manifestation was induced in microglia after activation with LPS (Miklossy et al., 2006; Gillardon et al., 2012; Moehle et al., 2012). Despite the reported effects in microglia, the relevance of LRRK2 with this immune cell is still under.