Critical role of regulator G-protein signaling 10 (RGS10) in modulating macrophage M1/M2 activation

Integration of transcriptome and Mendelian randomization analyses in exploring the extracellular vesicle-related biomarkers of diabetic kidney disease

BACKGROUND

Diabetic Kidney Disease (DKD) is a common complication in patients with diabetes, and its pathogenesis remains incompletely understood. Recent studies have suggested that extracellular vesicles (EVs) may play a significant role in the initiation and progression of DKD. This study aimed to identify biomarkers associated with EVs in DKD through bioinformatics and Mendelian randomization (MR) analysis.

METHODS

This study utilized two DKD-related datasets, GSE96804 and GSE30528, alongside 121 exosome-related genes (ERGs) and 200 inflammation-related genes (IRGs). Differential analysis, co-expression network construction, and MR analysis were conducted to identify candidate genes. Machine learning techniques and expression validation were then employed to determine biomarkers. Finally, the potential mechanisms of action of these biomarkers were explored through Immunohistochemistry (IHC) staining, enrichment analysis, immune infiltration analysis, and regulatory network construction.

RESULTS

A total of 22 candidate genes were identified as causally linked to DKD. CMAS and RGS10 were identified as biomarkers, with both showing reduced expression in DKD. IHC confirmed low RGS10 expression, providing new insights into DKD management. CMAS was involved primarily in mitochondria-related pathways, while RGS10 was enriched in the extracellular matrix and associated pathways. Significant differences were observed in neutrophils and M2 macrophages between DKD and normal groups, correlating strongly with the biomarkers.

CONCLUSION

This study identified two EV-associated biomarkers, CMAS and RGS10, linked to DKD and elucidated their potential roles in disease progression. These results offer valuable insights for further exploration of DKD pathogenesis and the development of new therapeutic targets.

Integrative genomics sheds light on the immunogenetics of tuberculosis in cattle

Mycobacterium bovis causes bovine tuberculosis (bTB), an infectious disease of cattle that represents a zoonotic threat to humans. Research has shown that the peripheral blood (PB) transcriptome is perturbed during bTB disease but the genomic architecture underpinning this transcriptional response remains poorly understood. Here, we analyse PB transcriptomics data from 63 control and 60 confirmed M. bovis-infected animals and detect 2592 differently expressed genes perturbing multiple immune response pathways. Leveraging imputed genome-wide SNP data, we characterise thousands of cis-expression quantitative trait loci (eQTLs) and show that the PB transcriptome is substantially impacted by intrapopulation genomic variation during M. bovis infection. Integrating our cis-eQTL data with bTB susceptibility GWAS summary statistics, we perform a transcriptome-wide association study and identify 115 functionally relevant genes (including RGS10, GBP4, TREML2, and RELT) and provide important new omics data for understanding the host response to mycobacterial infections that cause tuberculosis in mammals.

RGS10 attenuates systemic immune dysregulation induced by chronic inflammatory stress

Regulator of G-protein signaling 10 (RGS10), a key homeostatic regulator of immune cells, has been implicated in multiple diseases associated with aging and chronic inflammation including Parkinson's Disease (PD). Interestingly, subjects with idiopathic PD display reduced levels of RGS10 in subsets of peripheral immune cells. Additionally, individuals with PD have been shown to have increased activated peripheral immune cells in cerebrospinal fluid (CSF) compared to age-matched healthy controls. However, it is unknown whether peripheral immune cells in the CSF of individuals with PD also exhibit decreased levels of RGS10. Utilizing the Michael J. Fox Foundation Parkinson's Progression Markers Initiative (PPMI) study we found that RGS10 levels are decreased in the CSF of individuals with PD compared to healthy controls and prodromal individuals. As RGS10 levels are decreased in the CSF and circulating peripheral immune cells of individuals with PD, we hypothesized that RGS10 regulates peripheral immune cell responses to chronic systemic inflammation (CSI) prior to the onset of neurodegeneration. To test this, we induced CSI for 6 weeks in C57BL6/J mice and RGS10 KO mice to assess circulating and CNS-associated immune cell responses. We found that RGS10 deficiency synergizes with CSI to induce a bias for inflammatory and cytotoxic cell populations, a reduction in antigen presentation machinery in peripheral blood immune cells, as well as in and around the brain that is most notable in males. These results highlight RGS10 as an important regulator of the systemic immune response to CSI and implicate RGS10 as a potential contributor to the development of immune dysregulation in PD.

RGS10 Deficiency Alleviated Intestinal Mucosal Inflammation Through Suppression of Th1/Th17 Cell Immune Responses in Ulcerative Colitis

Regulator of G-protein signalling (RGS) 10 plays critical roles in several immune related diseases. However, whether RGS10 is involved in colonic inflammation of ulcerative colitis (UC) is still obscure. This study aimed to investigate the role of RGS10 in UC. In this study, RGS10 expression was examined by quantitative real-time polymerase chain reaction (qRT-PCR), western blotting, immunohistochemistry, and immunofluorescent analysis. Single-cell RNA sequencing of intestinal mucosa was performed to identify key immune cells with differentially expressed RGS10. RGS10 knockout mice were generated and established dextran sulphate sodium (DSS)-induced colitis. Expression of inflammatory cytokines on mRNA and protein levels was detected by qRT-PCR, enzyme-linked immunosorbent assay, and flow cytometry. We found that RGS10 expression was significantly elevated in UC patients, especially in CD4+ T cells, compared with healthy subjects. Intriguingly, RGS10 deficiency markedly alleviated DSS-induced colitis and decreased the proportion of Th1 and Th17 cells in lamina propria mononuclear cells (LPMCs), peripheral blood (PB), spleens, and mesenteric lymph nodes (mLNs). Mechanistically, RGS10 deficiency blocked the differentiation of Th1 and Th17 cells by inhibiting the phosphorylation of signal transducer and activator of transcription (STAT) 1 and STAT3. The co-immunoprecipitation analysis further showed that RGS10 could interact with protein tyrosine phosphatase non-receptor type 2 (PTPN2), and further regulated Th1 and Th17 cells differentiation of CD4+ T cells. In conclusion, RGS10 deficiency alleviated intestinal mucosal inflammation through inhibition of Th1/Th17 cell-mediated immune responses via interaction with PTPN2 in CD4+ T cells. Therefore, targeting RGS10 may represent a novel therapeutic approach for UC treatment.

A Phenotypic High-Throughput Screen Identifies Small Molecule Modulators of Endogenous RGS10 in BV-2 Cells

Chronic dysregulation of microglial phenotypic balance contributes to prolonged neuroinflammation and neurotoxicity, which is a hallmark of neurodegenerative diseases. Thus, targeting microglial inflammatory signaling represents a promising therapeutic strategy for neurodegenerative diseases. Regulator of G protein Signaling 10 (RGS10) is highly expressed in microglia, where it suppresses pro-inflammatory signaling. However, RGS10 is silenced following microglial activation, augmenting inflammatory responses. While modulating RGS10 expression is a promising strategy to suppress pro-inflammatory microglial activation, no chemical tools with this ability exist. We developed a phenotypic high-throughput assay to screen for compounds with the ability to reverse interferon-γ (IFNγ)-induced RGS10 silencing in BV-2 cells. Identified hits had no effect on RGS10 expression in the absence of stimulus or in response to lipopolysaccharide (LPS). Furthermore, the hits reversed some of the inflammatory gene expression induced by IFNγ. This is the first demonstration of the potential for small molecule intervention to modulate the RGS10 expression in microglia.

RGS10 Attenuates Systemic Immune Dysregulation Induced by Chronic Inflammatory Stress

Regulator of G-protein signaling 10 (RGS10), a key homeostatic regulator of immune cells, has been implicated in multiple diseases associated with aging and chronic inflammation including Parkinson's Disease (PD). Interestingly, subjects with idiopathic PD display reduced levels of RGS10 in subsets of peripheral immune cells. Additionally, individuals with PD have been shown to have increased activated peripheral immune cells in cerebral spinal fluid (CSF) compared to age-matched healthy controls. However, it is unknown whether CSF-resident peripheral immune cells in individuals with PD also exhibit decreased levels of RGS10. Therefore, we performed an analysis of RGS10 levels in the proteomic database of the CSF from the Michael J. Fox Foundation Parkinson's Progression Markers Initiative (PPMI) study. We found that RGS10 levels are decreased in the CSF of individuals with PD compared to healthy controls and prodromal individuals. Moreover, we find that RGS10 levels decrease with age but not PD progression and that males have less RGS10 than females in PD. Importantly, studies have established an association between chronic systemic inflammation (CSI) and neurodegenerative diseases, such as PD, and known sources of CSI have been identified as risk factors for developing PD; however, the role of peripheral immune cell dysregulation in this process has been underexplored. As RGS10 levels are decreased in the CSF and circulating peripheral immune cells of individuals with PD, we hypothesized that RGS10 regulates peripheral immune cell responses to CSI prior to the onset of neurodegeneration. To test this, we induced CSI for 6 weeks in C57BL6/J mice and RGS10 KO mice to assess circulating and CNS-associated peripheral immune cell responses. We found that RGS10 deficiency synergizes with CSI to induce a bias for inflammatory and cytotoxic cell populations, a reduction in antigen presentation in peripheral blood immune cells, as well as in and around the brain that is most notable in males. These results highlight RGS10 as an important regulator of the systemic immune response to CSI and implicate RGS10 as a potential contributor to the development of immune dysregulation in PD.

RGS10 mitigates high glucose-induced microglial inflammation via the reactive oxidative stress pathway and enhances synuclein clearance in microglia

Microglia play a critical role in maintaining brain homeostasis but become dysregulated in neurodegenerative diseases. Regulator of G-protein Signaling 10 (RGS10), one of the most abundant homeostasis proteins in microglia, decreases with aging and functions as a negative regulator of microglia activation. RGS10-deficient mice exhibit impaired glucose tolerance, and high-fat diet induces insulin resistance in these mice. In this study, we investigated whether RGS10 modulates microglia activation in response to hyperglycemic conditions, complementing our previous findings of its role in inflammatory stimuli. In RGS10 knockdown (KD) BV2 cells, TNF production increased significantly in response to high glucose, particularly under proinflammatory conditions. Additionally, glucose uptake and GLUT1 mRNA levels were significantly elevated in RGS10 KD BV2 cells. These cells produced higher ROS and displayed reduced sensitivity to the antioxidant N-Acetyl Cysteine (NAC) when exposed to high glucose. Notably, both BV2 cells and primary microglia that lack RGS10 exhibited impaired uptake of alpha-synuclein aggregates. These findings suggest that RGS10 acts as a negative regulator of microglia activation not only in response to inflammation but also under hyperglycemic conditions.

NLRP3 inflammasome in neurodegenerative disease

Neurodegenerative diseases are characterized by a dysregulated neuro-glial microenvironment, culminating in functional deficits resulting from neuronal cell death. Inflammation is a hallmark of the neurodegenerative microenvironment and despite a critical role in tissue homeostasis, increasing evidence suggests that chronic inflammatory insult can contribute to progressive neuronal loss. Inflammation has been studied in the context of neurodegenerative disorders for decades but few anti-inflammatory treatments have advanced to clinical use. This is likely due to the related challenges of predicting and mitigating off-target effects impacting the normal immune response while detecting inflammatory signatures that are specific to the progression of neurological disorders. Inflammasomes are pro-inflammatory cytosolic pattern recognition receptors functioning in the innate immune system. Compelling pre-clinical data has prompted an intense interest in the role of the NLR family pyrin domain containing 3 (NLRP3) inflammasome in neurodegenerative disease. NLRP3 is typically inactive but can respond to sterile triggers commonly associated with neurodegenerative disorders including protein misfolding and aggregation, mitochondrial and oxidative stress, and exposure to disease-associated environmental toxicants. Clear evidence of enhanced NLRP3 inflammasome activity in common neurodegenerative diseases has coincided with rapid advancement of novel small molecule therapeutics making the NLRP3 inflammasome an attractive target for near-term interventional studies. In this review, we highlight evidence from model systems and patients indicating inflammasome activity in neurodegenerative disease associated with the NLRP3 inflammasome's ability to recognize pathologic forms of amyloid-β, tau, and α-synuclein. We discuss inflammasome-driven pyroptotic processes highlighting the potential utility of evaluating extracellular inflammasome-related proteins in the context of biomarker discovery. We complete the report by pointing out gaps in our understanding of intracellular modifiers of inflammasome activity and mechanisms regulating the resolution of inflammasome activation. The literature review and perspectives provide a conceptual platform for continued analysis of inflammation in neurodegenerative diseases through the study of inflammasomes and pyroptosis, mechanisms of inflammation and cell death now recognized to function in multiple highly prevalent neurological disorders.

Pleiotropic effects of the COX-2/PGE2 axis in the glioblastoma tumor microenvironment

Glioblastoma (GBM) is the most common and aggressive form of malignant glioma. The GBM tumor microenvironment (TME) is a complex ecosystem of heterogeneous cells and signaling factors. Glioma associated macrophages and microglia (GAMs) constitute a significant portion of the TME, suggesting that their functional attributes play a crucial role in cancer homeostasis. In GBM, an elevated GAM population is associated with poor prognosis and therapeutic resistance. Neoplastic cells recruit these myeloid populations through release of chemoattractant factors and dysregulate their induction of inflammatory programs. GAMs become protumoral advocates through production a variety of cytokines, inflammatory mediators, and growth factors that can drive cancer proliferation, invasion, immune evasion, and angiogenesis. Among these inflammatory factors, cyclooxygenase-2 (COX-2) and its downstream product, prostaglandin E2 (PGE2), are highly enriched in GBM and their overexpression is positively correlated with poor prognosis in patients. Both tumor cells and GAMs have the ability to signal through the COX-2 PGE2 axis and respond in an autocrine/paracrine manner. In the GBM TME, enhanced signaling through the COX-2/PGE2 axis leads to pleotropic effects that impact GAM dynamics and drive tumor progression.

Inhibition of Rgs10 aggravates periodontitis with collagen-induced arthritis via the NF-κB pathway

OBJECTIVE

To explore the role of the Rgs10-associated nuclear factor (NF)-κB signalling pathway in periodontitis with rheumatoid arthritis.

METHODS

Porphyromonas gingivalis and collagen were locally applied to mice to establish in vivo periodontitis and rheumatoid arthritis models, respectively. Both agents were administered together to establish the comorbid group. All models were treated with adeno-associated virus-green fluorescent protein (AAV-GFP) or adeno-associated virus small hairpin Rgs10 (AAV-sh-Rgs10). In vivo expression of Rgs10 and inflammatory cytokines was analysed, along with exploration of the NF-κB signalling pathway in lipopolysaccharide (LPS)-stimulated mouse-derived RAW264.7 cells, with and without treatment of small interfering RNA (siRNA; Rgs10-Mus-MSS245072).

RESULTS

In the comorbidity mouse group (mice with both periodontitis and rheumatoid arthritis), inhibition of Rgs10 exacerbated periodontitis, along with upregulation of phospho-RelA (pP65), tumour necrosis factor-α (TNF-α), and interleukin-6 (IL-6) expression in the NF-κB signalling pathway. Similarly, treatment of LPS-stimulated RAW264.7 cells with siRNA resulted in the inhibition of Rgs10, along with upregulation of pP65, TNF-α, and IL-6 expression in vitro.

CONCLUSION

Inhibition of Rgs10 in mice with periodontitis and rheumatoid arthritis can promote the progression of periodontitis, indicating the potential therapeutic role of Rgs10 in this condition.

RGS10 Reduces Lethal Influenza Infection and Associated Lung Inflammation in Mice

Seasonal influenza epidemics represent a significant global health threat. The exacerbated immune response triggered by respiratory influenza virus infection causes severe pulmonary damage and contributes to substantial morbidity and mortality. Regulator of G-protein signaling 10 (RGS10) belongs to the RGS protein family that act as GTPase activating proteins for heterotrimeric G proteins to terminate signaling pathways downstream of G protein-coupled receptors. While RGS10 is highly expressed in immune cells, in particular monocytes and macrophages, where it has strong anti-inflammatory effects, its physiological role in the respiratory immune system has not been explored yet. Here, we show that Rgs10 negatively modulates lung immune and inflammatory responses associated with severe influenza H1N1 virus respiratory infection in a mouse model. In response to influenza A virus challenge, mice lacking RGS10 experience enhanced weight loss and lung viral titers, higher mortality and significantly faster disease onset. Deficiency of Rgs10 upregulates the levels of several proinflammatory cytokines and chemokines and increases myeloid leukocyte accumulation in the infected lung, markedly neutrophils, monocytes, and inflammatory monocytes, which is associated with more pronounced lung damage. Consistent with this, influenza-infected Rgs10-deficent lungs contain more neutrophil extracellular traps and exhibit higher neutrophil elastase activities than wild-type lungs. Overall, these findings propose a novel, in vivo role for RGS10 in the respiratory immune system controlling myeloid leukocyte infiltration, viral clearance and associated clinical symptoms following lethal influenza challenge. RGS10 also holds promise as a new, potential therapeutic target for respiratory infections.

Experimental colitis promotes sustained, sex-dependent, T-cell-associated neuroinflammation and parkinsonian neuropathology

Background

The etiology of sporadic Parkinson’s disease (PD) remains uncertain, but genetic, epidemiological, and physiological overlap between PD and inflammatory bowel disease suggests that gut inflammation could promote dysfunction of dopamine-producing neurons in the brain. Mechanisms behind this pathological gut-brain effect and their interactions with sex and with environmental factors are not well understood but may represent targets for therapeutic intervention.

Methods

We sought to identify active inflammatory mechanisms which could potentially contribute to neuroinflammation and neurological disease in colon biopsies and peripheral blood immune cells from PD patients. Then, in mouse models, we assessed whether dextran sodium sulfate-mediated colitis could exert lingering effects on dopaminergic pathways in the brain and whether colitis increased vulnerability to a subsequent exposure to the dopaminergic neurotoxicant 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). We assessed the involvement of inflammatory mechanisms identified in the PD patients in colitis-related neurological dysfunction in male and female mice, utilizing mice lacking the Regulator of G-Protein Signaling 10 (RGS10)—an inhibitor of nuclear factor kappa B (NFκB)—to model enhanced NFκB activity, and mice in which CD8⁺ T-cells were depleted.

Results

High levels of inflammatory markers including CD8B and NFκB p65 were found in colon biopsies from PD patients, and reduced levels of RGS10 were found in immune cells in the blood. Male mice that experienced colitis exhibited sustained reductions in tyrosine hydroxylase but not in dopamine as well as sustained CD8⁺ T-cell infiltration and elevated Ifng expression in the brain. CD8⁺ T-cell depletion prevented colitis-associated reductions in dopaminergic markers in males. In both sexes, colitis potentiated the effects of MPTP. RGS10 deficiency increased baseline intestinal inflammation, colitis severity, and neuropathology.

Conclusions

This study identifies peripheral inflammatory mechanisms in PD patients and explores their potential to impact central dopaminergic pathways in mice. Our findings implicate a sex-specific interaction between gastrointestinal inflammation and neurologic vulnerability that could contribute to PD pathogenesis, and they establish the importance of CD8⁺ T-cells in this process in male mice.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s40478-021-01240-4.

PI3K/ NF-κB-dependent TNF-α and HDAC activities facilitate LPS-induced RGS10 suppression in pulmonary macrophages

Regulator of G-protein signaling 10 (RGS10) is a member of the superfamily of RGS proteins that canonically act as GTPase activating proteins (GAPs). RGS proteins accelerate GTP hydrolysis on the G-protein α subunits and result in termination of signaling pathways downstream of G protein-coupled receptors. Beyond its GAP function, RGS10 has emerged as an anti-inflammatory protein by inhibiting LPS-mediated NF-κB activation and expression of inflammatory cytokines, in particular TNF-α. Although RGS10 is abundantly expressed in resting macrophages, previous studies have shown that RGS10 expression is suppressed in macrophages following Toll-like receptor 4 (TLR4) activation by LPS. However, the molecular mechanism by which LPS induces Rgs10 silencing has not been clearly defined. The goal of the current study was to determine whether LPS silences Rgs10 expression through an NF-κB-mediated proinflammatory mechanism in pulmonary macrophages, a unique type of innate immune cells. We demonstrate that Rgs10 transcript and RGS10 protein levels are suppressed upon LPS treatment in the murine MH-S alveolar macrophage cell line. We show that pharmacological inhibition of PI3K/ NF-κB/p300 (NF-κB co-activator)/TNF-α signaling cascade and the activities of HDAC (1-3) enzymes block LPS-induced silencing of Rgs10 in MH-S cells as well as microglial BV2 cells and BMDMs. Further, loss of RGS10 generated by using CRISPR/Cas9 amplifies NF-κB phosphorylation and inflammatory gene expression following LPS treatment in MH-S cells. Together, our findings strongly provide critical insight into the molecular mechanism underlying RGS10 suppression by LPS in pulmonary macrophages.

Short stature and combined immunodeficiency associated with mutations in RGS10

We report the clinical and molecular phenotype of three siblings from one family, who presented with short stature and immunodeficiency and carried uncharacterized variants in RGS10 (c.489_491del:p.E163del and c.G511T:p.A171S). This gene encodes regulator of G protein signaling 10 (RGS10), a member of a large family of GTPase-activating proteins (GAPs) that targets heterotrimeric G proteins to constrain the activity of G protein-coupled receptors, including receptors for chemoattractants. The affected individuals exhibited systemic abnormalities directly related to the RGS10 mutations, including recurrent infections, hypergammaglobulinemia, profoundly reduced lymphocyte chemotaxis, abnormal lymph node architecture, and short stature due to growth hormone deficiency. Although the GAP activity of each RGS10 variant was intact, each protein exhibited aberrant patterns of PKA-mediated phosphorylation and increased cytosolic and cell membrane localization and activity compared to the wild-type protein. We propose that the RGS10 p.E163del and p.A171S mutations lead to mislocalization of the RGS10 protein in the cytosol, thereby resulting in attenuated chemokine signaling. This study suggests that RGS10 is critical for both immune competence and normal hormonal metabolism in humans and that rare RGS10 variants may contribute to distinct systemic genetic disorders.

RGS10 physically and functionally interacts with STIM2 and requires store-operated calcium entry to regulate pro-inflammatory gene expression in microglia

Chronic activation of microglia is a driving factor in the progression of neuroinflammatory diseases, and mechanisms that regulate microglial inflammatory signaling are potential targets for novel therapeutics. Regulator of G protein Signaling 10 is the most abundant RGS protein in microglia, where it suppresses inflammatory gene expression and reduces microglia-mediated neurotoxicity. In particular, microglial RGS10 downregulates the expression of pro-inflammatory mediators including cyclooxygenase 2 (COX-2) following stimulation with lipopolysaccharide (LPS). However, the mechanism by which RGS10 affects inflammatory signaling is unknown and is independent of its canonical G protein targeted mechanism. Here, we sought to identify non-canonical RGS10 interacting partners that mediate its anti-inflammatory mechanism. Through RGS10 co-immunoprecipitation coupled with mass spectrometry, we identified STIM2, an endoplasmic reticulum (ER) localized calcium sensor and a component of the store-operated calcium entry (SOCE) machinery, as a novel RGS10 interacting protein in microglia. Direct immunoprecipitation experiments confirmed RGS10-STIM2 interaction in multiple microglia and macrophage cell lines, as well as in primary cells, with no interaction observed with the homologue STIM1. We further determined that STIM2, Orai channels, and the calcium-dependent phosphatase calcineurin are essential for LPS-induced COX-2 production in microglia, and this pathway is required for the inhibitory effect of RGS10 on COX-2. Additionally, our data demonstrated that RGS10 suppresses SOCE triggered by ER calcium depletion and that ER calcium depletion, which induces SOCE, amplifies pro-inflammatory genes. In addition to COX-2, we also show that RGS10 suppresses the expression of pro-inflammatory cytokines in microglia in response to thrombin and LPS stimulation, and all of these effects require SOCE. Collectively, the physical and functional links between RGS10 and STIM2 suggest a complex regulatory network connecting RGS10, SOCE, and pro-inflammatory gene expression in microglia, with broad implications in the pathogenesis and treatment of chronic neuroinflammation.

Exercise alters LPS-induced glial activation in the mouse brain

Experimental and epidemiological evidence suggest that modifiable lifestyle factors, including physical exercise, can build structural and cognitive reserve in the brain, increasing resilience to injury and insult. Accordingly, exercise can reduce the increased expression of proinflammatory cytokines in the brain associated with ageing or experimentally induced neuroinflammation. However, the cellular mechanisms by which exercise exerts this effect are unknown, including the effects of exercise on classic or alternative activation of astrocytes and microglia. In the present study, we assess the effects of nine consecutive days of treadmill running on the glial cell response to a single systemic injection of lipopolysaccharide (LPS) and, in parallel, the effects on spatial learning and memory. We show that prior exercise protects against LPS-induced impairment of performance in the object displacement task concomitant with attenuation of IL-1β, TNFα and IL-10 mRNA expression in the hippocampus. Assessment of isolated astrocytes and microglia revealed that LPS induced a proinflammatory response in these cells that was not observed in cells prepared from the brains of mice who had undergone prior exercise. The results suggest that exercise modulates neuroinflammation by reducing the proinflammatory microglial response, suggesting a mechanism by which exercise may be neuroprotective.

Regulator of G protein signaling 10: Structure, expression and functions in cellular physiology and diseases

Regulator of G protein signaling 10 (RGS10) belongs to the superfamily of RGS proteins, defined by the presence of a conserved RGS domain that canonically binds and deactivates heterotrimeric G-proteins. RGS proteins act as GTPase activating proteins (GAPs), which accelerate GTP hydrolysis on the G-protein α subunits and result in termination of signaling pathways downstream of G protein-coupled receptors. RGS10 is the smallest protein of the D/R12 subfamily and selectively interacts with Gαi proteins. It is widely expressed in many cells and tissues, with the highest expression found in the brain and immune cells. RGS10 expression is transcriptionally regulated via epigenetic mechanisms. Although RGS10 lacks multiple of the defined regulatory domains found in other RGS proteins, RGS10 contains post-translational modification sites regulating its expression, localization, and function. Additionally, RGS10 is a critical protein in the regulation of physiological processes in multiple cells, where dysregulation of its expression has been implicated in various diseases including Parkinson's disease, multiple sclerosis, osteopetrosis, chemoresistant ovarian cancer and cardiac hypertrophy. This review summarizes RGS10 features and its regulatory mechanisms, and discusses the known functions of RGS10 in cellular physiology and pathogenesis of several diseases.

N-acetyl cysteine, inulin and the two as a combined therapy ameliorate cognitive decline in testosterone-deprived rats

Our previous studies reported that testosterone-deprived rats developed cognitive decline as a result of increased brain oxidative stress, microglia hyperactivity, and hippocampal dysplasticity. In addition, gut dysbiosis occurred in these rats. Previous studies demonstrated that n-acetyl cysteine (NAC) and a prebiotic (inulin) improved cognition in several pathological conditions. However, its effects on cognition in the testosterone-deprived condition have never been investigated. This study hypothesized that the administration of NAC, inulin, and a combined therapy improved cognition in castrated rats. Here we report that metabolic disturbance was not observed in the ORX rats, but gut dysbiosis was found in these rats. ORX rats developed blood-brain-barrier (BBB) breakdown, and increased brain oxidative stress as indicated by increased hippocampal production of reactive oxygen species (ROS) and an increase in brain malondialdehyde level. ORX rats also demonstrated glia hyperactivation, resulting in hippocampal apoptosis, hippocampal dysplasticity, and cognitive decline. All treatments equally ameliorated cognitive decline by improving gut dysbiosis, alleviating BBB dysfunction, decreasing hippocampal ROS production, decreasing hippocampal apoptosis, and reducing microglia and astrocyte activity. These findings suggest that NAC, inulin, and the combined therapy ameliorated the deleterious effects on the brain in castrated male rats similar to those treated with testosterone.

An association between mitochondria and microglia effector function. What do we think we know?

While resident innate immune cells of the central nervous system, the microglia, represent a cell population unique in origin, microenvironment, and longevity, they assume many properties displayed by peripheral macrophages. One prominent shared property is the ability to undergo a metabolic switch towards glycolysis and away from oxidative phosphorylation (OXPHOS) upon activation by the pro-inflammatory stimuli lipopolysaccharide. This shift serves to meet specific cellular demands and allows for cell survival, similar to the Warburg effect demonstrated in cancer cells. In contrast, normal survelliance phenotype or stimulation to a non-proinflammatory phenotype relies primarily on OXPHOS and fatty acid oxidation. Thus, mitochondria appear to function as a pivotal signaling platform linking energy metabolism and macrophage polarization upon activation. These unique shifts in cell bioenergetics in response to different stimuli are essential for proper effector responses at sites of infection, inflammation, or injury. Here we present a summary of recent developments as to how these dynamics characterized in peripheral macrophages are displayed in microglia. The new insights provided by an increased understanding of metabolic reprogramming in macrophages may allow for translation to the CNS and a better understanding of microglia heterogeneity, regulation, and function.

RELMα-expressing macrophages protect against fatal lung damage and reduce parasite burden during helminth infection

Alternatively activated macrophages (AAMs) can contribute to wound healing, regulation of glucose and fat metabolism, resolution of inflammation, and protective immunity against helminths. Their differentiation, tissue distribution, and effector functions are incompletely understood. Murine AAMs express high levels of resistin-like molecule (RELM) α, an effector protein with potent immunomodulatory functions. To visualize RELMα⁺ macrophages (MΦs) in vivo and evaluate their role in defense against helminths, we generated RELMα reporter/deleter mice. Infection with the helminth Nippostrongylus brasiliensis induced expansion of RELMα⁺ lung interstitial but not alveolar MΦs in a STAT6-dependent manner. RELMα⁺ MΦs were required for prevention of fatal lung damage during primary infection. Furthermore, protective immunity was lost upon specific deletion of RELMα⁺ MΦs during secondary infection. Thus, RELMα reporter/deleter mice reveal compartmentalization of AAMs in different tissues and demonstrate their critical role in resolution of severe lung inflammation and protection against migrating helminths.

The Presence of High Levels of Circulating Trimethylamine N-Oxide Exacerbates Central and Peripheral Inflammation and Inflammatory Hyperalgesia in Rats Following Carrageenan Injection

Gut microbiota-derived metabolite trimethylamine N-oxide (TMAO) has recently been shown to promote inflammation in peripheral tissues and the central nervous system (CNS), contributing to the pathogenesis of various human diseases. Here, we examined whether the presence of high levels of circulating TMAO would influence central and peripheral inflammation and inflammatory hyperalgesia in a carrageenan (CG)-induced rat model of inflammation. Rats were treated with vehicle or TMAO in drinking water. After 2 weeks of treatment, rats received intraplantar injection of saline or CG into the hind paw. Acute nociception was unaltered in TMAO-treated rats that had elevated plasma TMAO. Following CG injection, TMAO-treated rats were significantly more sensitive to thermal and mechanical stimulation of the inflamed paw and displayed greater paw edema. Molecular studies revealed that CG injection induced increases in recruitment of neutrophils/macrophages in the paw and activation of microglia in the spinal cord, along with increased activation of nuclear factor (NF)-kB and production of proinflammatory mediators in both vehicle-treated rats and TMAO-treated rats. However, the increases in the above parameters were more pronounced in TMAO-treated rats. Moreover, TMAO treatment decreased protein levels of anti-inflammatory mediator regulator of G protein signaling (RGS)-10 in both saline-injected rats and CG-injected rats. These findings suggest that the presence of high levels of circulating TMAO downregulates anti-inflammatory mediator RGS10 in both peripheral tissues and the CNS, which may increase the susceptibility to inflammatory challenge-induced NF-kB activity, leading to greater increase in production of inflammatory mediators and consequent exacerbation of peripheral inflammation and inflammatory hyperalgesia.

Gαi2 Signaling Regulates Inflammasome Priming and Cytokine Production by Biasing Macrophage Phenotype Determination

Macrophages exist as innate immune subsets that exhibit phenotypic heterogeneity and functional plasticity. Their phenotypes are dictated by inputs from the tissue microenvironment. G-protein-coupled receptors are essential in transducing signals from the microenvironment, and heterotrimeric Gα signaling links these receptors to downstream effectors. Several Gα_i-coupled G-protein-coupled receptors have been implicated in macrophage polarization. In this study, we use genetically modified mice to investigate the role of Gα_i2 on inflammasome activity and macrophage polarization. We report that Gα_i2 in murine bone marrow-derived macrophages (BMDMs) regulates IL-1β release after activation of the NLRP3, AIM2, and NLRC4 inflammasomes. We show this regulation stems from the biased polarity of Gα_i2 deficient (Gnai2 ^-/-) and RGS-insensitive Gα_i2 (Gnai2 ^G184S/G184S) BMDMs. We determined that although Gnai2 ^G184S/G184S BMDMs (excess Gα_i2 signaling) have a tendency toward classically activated proinflammatory (M1) phenotype, Gnai2^-/- BMDMs (Gα_i2 deficient) are biased toward alternatively activated anti-inflammatory (M2) phenotype. Finally, we find that Gα_i2-deficient macrophages have increased Akt activation and IFN-β production but defects in ERK1/2 and STAT3 activation after LPS stimulation. Gα_i2-deficient macrophages also exhibit increased STAT6 activation after IL-4 stimulation. In summary, our data indicates that excess Gα_i2 signaling promotes an M1 macrophage phenotype, whereas Gα_i2 signaling deficiency promotes an M2 phenotype. Understanding Gα_i2-mediated effects on macrophage polarization may bring to light insights regarding disease pathogenesis and the reprogramming of macrophages for the development of novel therapeutics.

RGS10 Regulates the Expression of Cyclooxygenase-2 and Tumor Necrosis Factor Alpha through a G Protein-Independent Mechanism

The small regulator of G protein signaling protein RGS10 is a key regulator of neuroinflammation and ovarian cancer cell survival; however, the mechanism for RGS10 function in these cells is unknown and has not been linked to specific G protein pathways. RGS10 is highly enriched in microglia, and loss of RGS10 expression in microglia amplifies production of the inflammatory cytokine tumor necrosis factor α (TNFα) and enhances microglia-induced neurotoxicity. RGS10 also regulates cell survival and chemoresistance of ovarian cancer cells. Cyclooxygenase-2 (COX-2)-mediated production of prostaglandins such as prostaglandin E2 (PGE2) is a key factor in both neuroinflammation and cancer chemoresistance, suggesting it may be involved in RGS10 function in both cell types, but a connection between RGS10 and COX-2 has not been reported. To address these questions, we completed a mechanistic study to characterize RGS10 regulation of TNFα and COX-2 and to determine if these effects are mediated through a G protein-dependent mechanism. Our data show for the first time that loss of RGS10 expression significantly elevates stimulated COX-2 expression and PGE2 production in microglia. Furthermore, the elevated inflammatory signaling resulting from RGS10 loss was not affected by Gαi inhibition, and a RGS10 mutant that is unable to bind activated G proteins was as effective as wild type in inhibiting TNFα expression. Similarly, suppression of RGS10 in ovarian cancer cells enhanced TNFα and COX-2 expression, and this effect did not require Gi activity. Together, our data strongly indicate that RGS10 inhibits COX-2 expression by a G protein-independent mechanism to regulate inflammatory signaling in microglia and ovarian cancer cells.

Genetic Analysis of Rare Human Variants of Regulators of G Protein Signaling Proteins and Their Role in Human Physiology and Disease

Regulators of G protein signaling (RGS) proteins modulate the physiologic actions of many neurotransmitters, hormones, and other signaling molecules. Human RGS proteins comprise a family of 20 canonical proteins that bind directly to G protein-coupled receptors/G protein complexes to limit the lifetime of their signaling events, which regulate all aspects of cell and organ physiology. Genetic variations account for diverse human traits and individual predispositions to disease. RGS proteins contribute to many complex polygenic human traits and pathologies such as hypertension, atherosclerosis, schizophrenia, depression, addiction, cancers, and many others. Recent analysis indicates that most human diseases are due to extremely rare genetic variants. In this study, we summarize physiologic roles for RGS proteins and links to human diseases/traits and report rare variants found within each human RGS protein exome sequence derived from global population studies. Each RGS sequence is analyzed using recently described bioinformatics and proteomic tools for measures of missense tolerance ratio paired with combined annotation-dependent depletion scores, and protein post-translational modification (PTM) alignment cluster analysis. We highlight selected variants within the well-studied RGS domain that likely disrupt RGS protein functions and provide comprehensive variant and PTM data for each RGS protein for future study. We propose that rare variants in functionally sensitive regions of RGS proteins confer profound change-of-function phenotypes that may contribute, in newly appreciated ways, to complex human diseases and/or traits. This information provides investigators with a valuable database to explore variation in RGS protein function, and for targeting RGS proteins as future therapeutic targets.

The possible factors affecting microglial activation in cases of obesity with cognitive dysfunction

Obesity has reached epidemic proportions in many countries around the world. Several studies have reported that obesity can lead to the development of cognitive decline. There is increasing evidence to demonstrate that microglia play a crucial role in cognitive decline in cases of obesity, Alzheimer's disease and also in the aging process. Although there have been several studies into microglia over the past decades, the mechanistic link between microglia and cognitive decline in obese models is still not fully understood. In this review, the current available evidence from both in vitro and in vivo investigations regarding the association between the alteration in microglial activity in different obese models with respect to cognition are included. The metabolite profiles from obesity, adiposity, dietary and hormone affected microglial activation and its function in the brain are comprehensively summarized. In addition, the possible roles of microglial activation in relation to cognitive dysfunction are also presented and discussed. To ensure a balanced perspective controversial reports regarding these issues are included and discussed.

Microglial phenotypes in Parkinson's disease and animal models of the disease

Over the last decade the important concept has emerged that microglia, similar to other tissue macrophages, assume different phenotypes and serve several effector functions, generating the theory that activated microglia can be organized by their pro-inflammatory or anti-inflammatory and repairing functions. Importantly, microglia exist in a heterogenous population and their phenotypes are not permanently polarized into two categories; they exist along a continuum where they acquire different profiles based on their local environment. In Parkinson's disease (PD), neuroinflammation and microglia activation are considered neuropathological hallmarks, however their precise role in relation to disease progression is not clear, yet represent a critical challenge in the search of disease-modifying strategies. This review will critically address current knowledge on the activation states of microglia as well as microglial phenotypes found in PD and in animal models of PD, focusing on the expression of surface molecules as well as pro-inflammatory and anti-inflammatory cytokine production during the disease process. While human studies have reported an elevation of both pro- or anti-inflammatory markers in the serum and CSF of PD patients, animal models have provided insights on dynamic changes of microglia phenotypes in relation to disease progression especially prior to the development of motor deficits. We also review recent evidence of malfunction at multiple steps of NFκB signaling that may have a causal interrelationship with pathological microglia activation in animal models of PD. Finally, we discuss the immune-modifying strategies that have been explored regarding mechanisms of chronic microglial activation.

RGS10 Negatively Regulates Platelet Activation and Thrombogenesis

Regulators of G protein signaling (RGS) proteins act as GTPase activating proteins to negatively regulate G protein-coupled receptor (GPCR) signaling. Although several RGS proteins including RGS2, RGS16, RGS10, and RGS18 are expressed in human and mouse platelets, the respective unique function(s) of each have not been fully delineated. RGS10 is a member of the D/R12 subfamily of RGS proteins and is expressed in microglia, macrophages, megakaryocytes, and platelets. We used a genetic approach to examine the role(s) of RGS10 in platelet activation in vitro and hemostasis and thrombosis in vivo. GPCR-induced aggregation, secretion, and integrin activation was much more pronounced in platelets from Rgs10-/- mice relative to wild type (WT). Accordingly, these mice had markedly reduced bleeding times and were more susceptible to vascular injury-associated thrombus formation than control mice. These findings suggest a unique, non-redundant role of RGS10 in modulating the hemostatic and thrombotic functions of platelets in mice. RGS10 thus represents a potential therapeutic target to control platelet activity and/or hypercoagulable states.

The impact of RGS and other G-protein regulatory proteins on Gαi-mediated signaling in immunity

Leukocyte chemoattractant receptors are members of the G-protein coupled receptor (GPCR) family. Signaling downstream of these receptors directs the localization, positioning and homeostatic trafficking of leukocytes; as well as their recruitment to, and their retention at, inflammatory sites. Ligand induced changes in the molecular conformation of chemoattractant receptors results in the engagement of heterotrimeric G-proteins, which promotes α subunits to undergo GTP/GDP exchange. This results in the functional release of βγ subunits from the heterotrimers, thereby activating downstream effector molecules, which initiate leukocyte polarization, gradient sensing, and directional migration. Pertussis toxin ADP ribosylates Gαi subunits and prevents chemoattractant receptors from triggering Gαi nucleotide exchange. The use of pertussis toxin revealed the essential importance of Gαi subunit nucleotide exchange for chemoattractant receptor signaling. More recent studies have identified a range of regulatory mechanisms that target these receptors and their associated heterotrimeric G-proteins, thereby helping to control the magnitude, kinetics, and duration of signaling. A failure in these regulatory pathways can lead to impaired receptor signaling and immunopathology. The analysis of mice with targeted deletions of Gαi isoforms as well as some of these G-protein regulatory proteins is providing insights into their roles in chemoattractant receptor signaling.

Role of NOS2 in pulmonary injury and repair in response to bleomycin

Nitric oxide (NO) is derived from multiple isoforms of the Nitric Oxide Synthases (NOSs) within the lung for a variety of functions; however, NOS2-derived nitrogen oxides seem to play an important role in inflammatory regulation. In this study, we investigate the role of NOS2 in pulmonary inflammation/fibrosis in response to intratracheal bleomycin instillation (ITB) and to determine if these effects are related to macrophage phenotype. Systemic NOS2 inhibition was achieved by administration of 1400W, a specific and potent NOS2 inhibitor, via osmotic pump starting six days prior to ITB. 1400W administration attenuated lung inflammation, decreased chemotactic activity of the broncheoalveolar lavage (BAL), and reduced BAL cell count and nitrogen oxide production. S-nitrosylated SP-D (SNO-SP-D), which has a pro-inflammatory function, was formed in response to ITB; but this formation, as well as structural disruption of SP-D, was inhibited by 1400W. mRNA levels of IL-1β, CCL2 and Ptgs2 were decreased by 1400W treatment. In contrast, expression of genes associated with alternate macrophage activation and fibrosis Fizz1, TGF-β and Ym-1 was not changed by 1400W. Similar to the effects of 1400W, NOS2-/- mice displayed an attenuated inflammatory response to ITB (day 3 and day 8 post-instillation). The DNA-binding activity of NF-κB was attenuated in NOS2-/- mice; in addition, expression of alternate activation genes (Fizz1, Ym-1, Gal3, Arg1) was increased. This shift towards an increase in alternate activation was confirmed by western blot for Fizz-1 and Gal-3 that show persistent up-regulation 15 days after ITB. In contrast arginase, which is increased in expression at 8 days post ITB in NOS2-/-, resolves by day 15. These data suggest that NOS2, while critical to the development of the acute inflammatory response to injury, is also necessary to control the late phase response to ITB.

RGS10 deficiency ameliorates the severity of disease in experimental autoimmune encephalomyelitis

Background

Regulator of G-protein signaling (RGS) family proteins, which are GTPase accelerating proteins (GAPs) that negatively regulate G-protein-coupled receptors (GPCRs), are known to be important modulators of immune cell activation and function. Various single-nucleotide polymorphisms in RGS proteins highly correlate with increased risk for multiple sclerosis (MS), an autoimmune, neurodegenerative disorder. An in-depth search of the gene expression omnibus profile database revealed higher levels of RGS10 and RGS1 transcripts in peripheral blood mononuclear cells (PBMCs) in MS patients, suggesting potential functional roles for RGS proteins in MS etiology and/or progression.

Methods

To define potential roles for RGS10 in regulating autoimmune responses, we evaluated RGS10-null and wild-type (WT) mice for susceptibility to experimental autoimmune encephalomyelitis (EAE), a widely studied model of MS. Leukocyte distribution and functional responses were assessed using biochemical, immunohistological, and flow cytometry approaches.

Results

RGS10-null mice displayed significantly milder clinical symptoms of EAE with reduced disease incidence and severity, as well as delayed onset. We observed fewer CD3+ T lymphocytes and CD11b+ myeloid cells in the central nervous system (CNS) tissues of RGS10-null mice with myelin oligodendrocyte protein (MOG)_35–55-induced EAE. Lymph node cells and splenocytes of immunized RGS10-null mice demonstrated decreased proliferative and cytokine responses in response to in vitro MOG memory recall challenge. In adoptive recipients, transferred myelin-reactive RGS10-null Th1 cells (but not Th17 cells) induced EAE that was less severe than their WT counterparts.

Conclusions

These data demonstrate a critical role for RGS10 in mediating autoimmune disease through regulation of T lymphocyte function. This is the first study ever conducted to elucidate the function of RGS10 in effector lymphocytes in the context of EAE. The identification of RGS10 as an important regulator of inflammation might open possibilities for the development of more specific therapies for MS.

Inhibition of Rho-kinase by Fasudil protects dopamine neurons and attenuates inflammatory response in an intranasal lipopolysaccharide-mediated Parkinson's model

Microglia activation and inflammatory factors in brain microenvironment are associated with degeneration of neurons in the substantia nigra (SN) of Parkinson's disease (PD) patients and various PD models. There is increasing evidence that the Rho/ROCK (Rho kinase) signalling pathway may play a critical role in the inflammatory response, and ROCK inhibitor has been reported to have neuroprotective effects. In this study, we examined the neuroprotective potential and possible mechanism of ROCK inhibitor Fasudil in an intranasal lipopolysaccharide (LPS)-induced PD model. ROCK was activated with LPS stimulation and inhibited by Fasudil treatment in this PD model. Behavioural tests demonstrated a clear improvement in motor performance after Fasudil treatment. Furthermore, Fasudil resulted in a significant attenuation of dopamine cell loss, α-synuclein accumulation and inflammatory response with the reversion of inflammatory M1 to anti-inflammatory M2 microglia, decreased NF-кB activation, and IL-12 and TNF-α generation in the SN and olfactory bulb in this model. This study establishes a role for Fasudil in protecting against LPS-mediated dopamine degeneration and provides a therapeutic strategy for the treatment of PD.

Cellular deficiency in the RGS10 protein facilitates chemoresistant ovarian cancer

More than 30 regulators of G protein signaling (RGS) proteins encompass the RGS protein superfamily of critical regulators essential to cellular homeostasis. There is enormous structural and functional diversity among the RGS superfamily, and as such they serve a wide range of functions in regulating cell biology and physiology. Recent evidence has suggested roles for multiple RGS proteins in cancer initiation and progression, which has prompted research toward the potential modulation of these proteins as a new approach in cancer therapy. This article will discuss basic RGS molecular pharmacology, summarize the cellular functions and epigenetic regulation of RGS10, review ovarian cancer chemotherapy and describe the role of RGS10 in ovarian cancer survival signaling.

Understanding the Mysterious M2 Macrophage through Activation Markers and Effector Mechanisms

The alternatively activated or M2 macrophages are immune cells with high phenotypic heterogeneity and are governing functions at the interface of immunity, tissue homeostasis, metabolism, and endocrine signaling. Today the M2 macrophages are identified based on the expression pattern of a set of M2 markers. These markers are transmembrane glycoproteins, scavenger receptors, enzymes, growth factors, hormones, cytokines, and cytokine receptors with diverse and often yet unexplored functions. This review discusses whether these M2 markers can be reliably used to identify M2 macrophages and define their functional subdivisions. Also, it provides an update on the novel signals of the tissue environment and the neuroendocrine system which shape the M2 activation. The possible evolutionary roots of the M2 macrophage functions are also discussed.

Role of Regulators of G Protein Signaling Proteins in Bone Physiology and Pathophysiology

Regulators of G protein signaling (RGS) proteins enhance the intrinsic GTPase activity of α subunits of the heterotrimeric G protein complex of G protein-coupled receptors (GPCRs) and thereby inactivate signal transduction initiated by GPCRs. The RGS family consists of nearly 37 members with a conserved RGS homology domain which is critical for their GTPase accelerating activity. RGS proteins are expressed in most tissues, including heart, lung, brain, kidney, and bone and play essential roles in many physiological and pathological processes. In skeletal development and bone homeostasis as well as in many bone disorders, RGS proteins control the functions of various GPCRs, including the parathyroid hormone receptor type 1 and calcium-sensing receptor and also regulate various critical signaling pathways, such as Wnt and calcium oscillations. This chapter will discuss the current findings on the roles of RGS proteins in regulating signaling of key GPCRs in skeletal development and bone homeostasis. We also will examine the current updates of RGS proteins' regulation of calcium oscillations in bone physiology and highlight the roles of RGS proteins in selected bone pathological disorders. Despite the recent advances in bone and mineral research, RGS proteins remain understudied in the skeletal system. Further understanding of the roles of RGS proteins in bone should not only provide great insights into the molecular basis of various bone diseases but also generate great therapeutic drug targets for many bone diseases.

Age-related changes in regulator of G-protein signaling (RGS)-10 expression in peripheral and central immune cells may influence the risk for age-related degeneration

Inflammation in the aging brain increases risk for neurodegenerative disease. In humans, the regulator of G-protein signaling-10 (RGS10) locus has been associated with age-related maculopathy. Chronic peripheral administration of lipopolysaccharide in the RGS10-null mice induces nigral dopaminergic (DA) degeneration, suggesting that RGS10 modulates neuroimmune interactions and may influence susceptibility to neurodegeneration. Because age is the strongest risk factor for neurodegenerative disease, we assessed whether RGS10 expression changes with age and whether aged RGS10-null mice have altered immune cell profiles. Loss of RGS10 in aged mice does not alter the regulation of nigral DA neurons but does alter B-cell, monocyte, microglial, and CD4+ T-cell populations and inflammatory cytokine levels in the cerebrospinal fluid. These results suggest that loss of RGS10 is associated with an age-dependent dysregulation of peripheral and central immune cells rather than dysregulation of DA neuron function.

Neuroinflammation in Alzheimer's disease; A source of heterogeneity and target for personalized therapy

Neuroinflammation has long been known as an accompanying pathology of Alzheimer's disease. Microglia surrounding amyloid plaques in the brain of Auguste D were described in the original publication of Alois Alzheimer. It is only quite recently, however, that we have a more complete appreciation for the diverse roles of neuroinflammation in neurodegenerative disorders such as Alzheimer's. While gaps in our knowledge remain, and conflicting data are abound in the field, our understanding of the complexities and heterogeneous functions of the inflammatory response in Alzheimer's is vastly improved. This review article will discuss some of the roles of neuroinflammation in Alzheimer's disease, in particular, how understanding heterogeneity in the individual inflammatory response can be used in therapeutic development and as a mechanism of personalizing our treatment of the disease.