TAMI-38. TUMOR-ASSOCIATED NEUTROPHILS IN GLIOBLASTOMA PROMOTE THE PERIVASCULAR GLIOMA STEM-LIKE CELL NICHE VIA OSTEOPONTIN SECRETION

2021 ◽  
Vol 23 (Supplement_6) ◽  
pp. vi206-vi206
Author(s):  
Angad Beniwal ◽  
Saket Jain ◽  
Sumedh Shah ◽  
Sabraj Gill ◽  
Garima Yagnik ◽  
...  
Keyword(s):  
Peripheral Blood ◽  
Leukotriene B4 ◽  
Lower Grade ◽  
Wild Type ◽  
Perivascular Niche ◽  
Neutrophil Lymphocyte Ratio ◽  
Blood Neutrophils ◽  
Poor Outcomes ◽  
Tumor Associated Neutrophils

Abstract Among clinical analyses, elevated neutrophil-lymphocyte ratio has been correlated with poor outcomes of glioblastoma patients independent of other prognostic factors. Additionally, our flow cytometric studies of primary patient samples found neutrophil percentage to be significantly higher in higher-grade glioma versus lower-grade glioma. Tumor-associated neutrophils (TANs) comprise less than 2% of the glioblastoma microenvironment. While TANs were initially considered passive bystanders due to their short-lived nature, investigation of TANs in other cancers revealed distinct pro-tumoral roles. Therefore, we transcriptomically characterized glioblastoma TANs and defined their oncologic effects. Transcriptomic analysis of patient-matched TANs versus peripheral blood neutrophils revealed that functionally quiescent circulating neutrophils infiltrate IDH1-wild type glioblastoma via leukotriene B4 chemoattraction, where tumor cells morphologically and transcriptomically activate them to become TANs. Single-cell RNA-sequencing of patient-matched TANs and peripheral blood neutrophils revealed a subset of tumor-activated neutrophils which adopt a pro-tumoral secretory phenotype, marked by activation of the IL-17 signaling pathway and high osteopontin production. Using immunofluorescence stains of primary patient glioblastoma sections, we demonstrated that activated, myeloperoxidase-positive TANs reside in the perivascular niche of glioblastoma in close proximity to glioblastoma stem-like cells (GSCs) and CD31-positive endothelial cells. Further analysis in culture demonstrated that TAN-secreted osteopontin drives the formation, self-renewal, and proliferation of GSC-containing neurospheres. These results were validated using a syngeneic stem cell-derived IDH1-wild type murine glioblastoma model in vivo. Thus, while TANs are rare in glioblastoma, their enrichment in the glioblastoma perivascular niche uniquely positions them to support the GSCs that are crucial to therapeutic resistance of GBM.

scholarly journals Cytokine-Activated Endothelial Cells Delay Neutrophil Apoptosis in Vitro and in Vivo

1999 ◽  
Vol 190 (7) ◽  
pp. 923-934 ◽  
Author(s):  
Angela Coxon ◽  
Tao Tang ◽  
Tanya N. Mayadas
Keyword(s):  
Endothelial Cells ◽  
Peripheral Blood ◽  
Neutrophil Apoptosis ◽  
Wild Type ◽  
Gm Csf ◽  
Acute Meningitis ◽  
Blood Neutrophils ◽  
And Function

The activation of endothelium is important in recruiting neutrophils to sites of inflammation and in modulating their function. We demonstrate that conditioned medium from cultured, activated endothelial cells acts to significantly delay the constitutive apoptosis of neutrophils, resulting in their enhanced survival and increased phagocytic function. The antiapoptotic activity is, in part, attributable to granulocyte/macrophage colony-stimulating factor (GM-CSF) secreted by activated endothelial cells. The in vivo relevance of these findings was investigated in a cytokine-induced model of acute meningitis in mice. Peripheral blood neutrophils (PBNs) from mice with meningitis exhibited a delay in apoptosis compared with untreated mice. Furthermore, neutrophils recovered from the inflamed cerebrospinal fluid (CSF) exhibited enhanced survival compared with neutrophils isolated from the peripheral blood of the same animals. In unchallenged GM-CSF–deficient mice, the apoptosis of circulating PBNs was similar to wild-type animals; however, after cytokine-induced meningitis, the delay in neutrophil apoptosis typically observed in wild-type mice was attenuated. In contrast, the apoptosis of neutrophils recovered from the CSF of mice of both genotypes was comparable. Taken together, these studies suggest that neutrophil apoptosis is regulated during an inflammatory response, in both intravascular and extravascular compartments. GM-CSF released by activated endothelium can act to increase neutrophil survival and function in the peripheral blood, whereas other factor(s) appear to perform this function in the extravascular space.

scholarly journals Accelerated Neutrophil Apoptosis in Mice Lacking A1-a, a Subtype of the bcl-2–related A1 Gene

1998 ◽  
Vol 188 (11) ◽  
pp. 1985-1992 ◽  
Author(s):  
Azumi Hamasaki ◽  
Fujiro Sendo ◽  
Keiko Nakayama ◽  
Noriko Ishida ◽  
Izumi Negishi ◽  
...  
Keyword(s):  
Neutrophil Apoptosis ◽  
Spontaneous Apoptosis ◽  
Wild Type ◽  
Apoptosis Inhibition ◽  
Blood Neutrophils ◽  
Factor Α ◽  
Necrosis Factor

To elucidate the role of A1, a new member of the Bcl-2 family of apoptosis regulators active in hematopoietic cell apoptosis, we established mice lacking A1-a, a subtype of the A1 gene in mice (A1-a−/− mice). Spontaneous apoptosis of peripheral blood neutrophils of A1-a−/− mice was enhanced compared with that of either wild-type mice or heterozygous mutants (A1-a+/− mice). Neutrophil apoptosis inhibition induced by lipopolysaccharide treatment in vitro or transendothelial migration in vivo observed in wild-type mice was abolished in both A1-a−/− and A1-a+/− animals. On the other hand, the extent of tumor necrosis factor α–induced acceleration of neutrophil apoptosis did not differ among A1-a−/−, A1-a+/−, and wild-type mice. The descending order of A1 mRNA expression was wild-type, A1-a+/−, and A1-a−/−. Taken together, these results suggest that A1 is involved in inhibition of certain types of neutrophil apoptosis.

Additional Environmental and/or Genetic Factors Are Required to Trigger TTP in ADAMTS13-Deficient Mice.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 258-258
Author(s):  
David Motto ◽  
Weirui Zhang ◽  
Guojing Zhu ◽  
Jonathon Homeister ◽  
Han-Mou Tsai ◽  
...  
Keyword(s):  
Hemolytic Anemia ◽  
Peripheral Blood ◽  
Protease Activity ◽  
Gene Mutations ◽  
Genetic Modifiers ◽  
Wild Type ◽  
Life Threatening ◽  
Von Willebrand ◽  
Deficient Mice

Abstract Thrombotic Thrombocytopenic Purpura (TTP) is a life threatening systemic illness characterized by the formation of platelet-rich thrombi in the microcirculation and the clinical pentad of fever, hemolytic anemia, thrombocytopenia, neurological symptoms, and renal dysfunction. TTP is associated with ultra-large von Willebrand Factor multimers (UL-VWF) in the circulation due to deficiency of the ADAMTS13 metalloprotease. ADAMTS13 gene mutations account for most if not all cases of familial TTP, and autoantibodies to ADAMTS13 underlie most cases of acquired TTP. To further explore the pathogenesis of TTP in vivo, ADAMTS13 deficient mice were generated by gene targeting to remove exons 1–6 which encode most of the protease domain of ADAMTS13. Although the resulting homozygous null mice (Adamts13−/−) have lost all specific VWF-cleaving protease activity (< 1% of control), embryonic development is normal, and the null mice are born at the expected Mendelian frequency. Analysis of baseline hematologic parameters and peripheral blood smears revealed no difference between Adamts13−/− mice and wild-type littermates, with no evidence for thrombocytopenia or microangiopathic hemolytic anemia. Pathologic survey of multiple tissues revealed only normal histology and no evidence for platelet or VWF-rich thrombi in the vasculature. Despite the absence of VWF-cleaving protease activity, plasma from wild-type and ADAMTS13-deficient mice exhibited identical VWF multimer size distributions. However, VWF multimers from both wild-type and Adamts13−/− mice were observed to be considerably larger than those from normal human plasma, and equivalent in size to UL-VWF seen in plasma from familial TTP patients. Challenge of Adamts13−/− mice by injection with endotoxin, and genetic crosses to mice with markedly elevated VWF levels (CASA/Rk), failed to induce findings consistent with TTP. However, treatment with verotoxin-2 (a bacterial endothelial toxin important in the pathogenesis of the hemolytic uremic syndrome), caused thrombocytopenia in 6 of 11 Adamts13−/− mice (vs. 3 of 11 wild-type controls, p < 0.07) and mortality at 6 days in 9 of 11 Adamts13−/− mice (vs. 6 of 11 controls, p < 0.02). Examination of peripheral blood from one of the Adamts13−/− mice at 8 days following verotoxin administration demonstrated marked microangiopathic changes. In conclusion, mice with targeted disruption of the Adamts13 gene do not develop TTP spontaneously, suggesting the requirement for additional environmental triggers or genetic modifiers. Though some humans with congenital ADAMTS13 deficiency have been reported to remain asymptomatic for many years, the increased size of the baseline VWF multimer distribution in mice may indicate a higher threshold for VWF-ADAMTS13 interaction which may be protective for TTP. Our results also suggest that microbial-derived toxins, or other sources of endothelial injury, may be one of the key environmental triggers responsible for the lack of spontaneous TTP findings in the ADAMTS13-deficient mice, and possibly for the intermittent symptoms seen in humans.

scholarly journals MBNL1 As a New Therapeutic Target in MLL-Fusion Gene Leukemia

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 462-462 ◽  
Author(s):  
Svetlana S Itskovich ◽  
Jason Clark ◽  
James C. Mulloy ◽  
Matthew D Disney ◽  
Ashish R Kumar
Keyword(s):  
Bone Marrow ◽  
Cord Blood ◽  
Peripheral Blood ◽  
Fusion Gene ◽  
Leukemia Cell ◽  
Leukemia Cells ◽  
Transformed Cells ◽  
Wild Type

Abstract Translocations of the Mixed Lineage Leukemia (MLL) gene located on chromosome 11 are commonly found in infants with AML or ALL and in secondary leukemia at all ages. A majority of patients with these translocations have a poor prognosis. Gene expression profiling studies demonstrate that one of the most consistently overexpressed genes in these leukemias (compared to all other leukemias) is muscleblind-like 1 (MBNL1). Further, MBNL1 was also identified as a direct transcriptional target of MLL-fusion proteins. An RNA-binding protein, MBNL1 is known to be a key factor in the pathophysiology of Myotonic Dystrophy Type I (DM), where sequestration of MBNL1 leads to splicing defects in muscle and neuronal cells. However, the role of MBNL1 in hematopoiesis and leukemogenesis is unknown. To determine the role of MBNL1 in normal hematopoiesis we studied MBNL1-/- mice. Compared to littermate controls, MBNL1-/- mice showed no differences in peripheral blood counts or bone marrow cellularity. When challenged with 5-FU, both MBNL1-/- and wild type mice displayed similar kinetics of peripheral blood cytopenia and recovery. Next we examined the role of MBNL1 in hematopoietic stem cell function using a competitive transplantation assay. Lethally irradiated mice were transplanted with a 1:1 mix of CD45.1 and CD45.2 bone marrow, with the latter being wild-type or MBNL1-/-. Flow cytometry analysis of peripheral blood at 4 weeks post-transplant showed donor chimerism being 53±4.14% in recipients of wild type marrow and 25±5.41 % in the MBNL1-/- recipients. Successive analyses every 4 weeks showed the chimerism to be stable over the next 16 weeks. To determine the role of MBNL1 in leukemia, we transformed MBNL1-/- or wild type bone marrow cells with various oncogenes delivered via retroviral transduction and compared them in methylcellulose colony replating assays. Absence of MBNL1 significantly reduced colony formation in MLL-AF9 and E2A-HLF transformed cells by 59.5% (± 27.1) and 50.7% (± 23) respectively, compared to controls. To assess the role of MBNL1 in leukemia in vivo, we transplanted MLL-AF9-transformed wild type or MBNL1-/- cells into irradiated mice. All recipients injected with wild-type MLL-AF9-transformed cells succumbed to leukemia with a median time of 106 days. In contrast, the majority of recipients of MBNL1-/- cells survived leukemia-free for at least 140 days post-transplantation (p=0.0017, log rank test). We next assessed the role of MBNL1 in human leukemia cells. Lentiviral-shRNA knockdown of MBNL1 in leukemia cell lines (MV4;11, THP-1) significantly inhibited cell growth, both in liquid culture and methylcellulose colony forming assays. To determine the requirement of MBNL1 for leukemia propagation in vivo, we used cord blood-derived leukemia cells bearing the MLL-AF9 fusion gene and mutant NRAS (MA9NRAS). MA9NRAS cells transduced with MBNL1-specific or control (non-targeting, NT) shRNA were transplanted into immunodeficient mice. Six weeks after transplant, bone marrow aspirates showed persistence of lentiviral-transduced cells in 85% of the NT-group. On the other hand, MBNL1-shRNA transduced cells were not detected in any of the recipient mice. These results suggest that MBNL1 is essential for leukemia cell propagation in vivo. Finally, we tested therapeutic targeting of MBNL1 in MLL-fusion gene leukemia. A lead inhibitor that prevents binding of MBNL1 to its targets was recently identified. Treatment of MA9NRAS cells with the inhibitor for 48 hours led to significant apoptosis whereas normal cord blood CD34+ cells were relatively less sensitive. Blockade of MBNL1 in leukemia cells either by shRNA-knockdown or by the inhibitor showed identical changes in splicing patterns of known MBNL1 target genes. Collectively, our data suggest that MBNL1 is required for the initiation and propagation of MLL-fusion gene leukemia while it appears relatively dispensable for normal hematopoiesis. Further, we have identified a promising lead inhibitor that could be developed for novel treatments for therapy-resistant leukemias. Disclosures No relevant conflicts of interest to declare.

scholarly journals NFIL3 Facilitates Neutrophil Autophagy, Neutrophil Extracellular Trap Formation and Inflammation During Gout via REDD1-Dependent mTOR Inactivation

2021 ◽  
Vol 8 ◽  
Author(s):  
Honghu Tang ◽  
Chunyu Tan ◽  
Xue Cao ◽  
Yi Liu ◽  
Hua Zhao ◽  
...  
Keyword(s):  
Peripheral Blood ◽  
Expression Patterns ◽  
Gouty Arthritis ◽  
Mtor Pathway ◽  
Neutrophil Extracellular Trap ◽  
Inflammatory Factors ◽  
Loss Of Function ◽  
Blood Neutrophils

Autophagy pathways play an important role in immunity and inflammation via pathogen clearance mechanisms mediated by immune cells, such as macrophages and neutrophils. In particular, autophagic activity is essential for the release of neutrophil extracellular traps (NETs), a distinct form of active neutrophil death. The current study set out to elucidate the mechanism of the NFIL3/REDD1/mTOR axis in neutrophil autophagy and NET formation during gout inflammation. Firstly, NFIL3 expression patterns were determined in the peripheral blood neutrophils of gout patients and monosodium urate (MSU)-treated neutrophils. Interactions between NFIL3 and REDD1 were identified. In addition, gain- or loss-of-function approaches were used to manipulate NFIL3 and REDD1 in both MSU-induced neutrophils and mice. The mechanism of NFIL3 in inflammation during gout was evaluated both in vivo and in vitro via measurement of cell autophagy, NET formation, MPO activity as well as levels of inflammatory factors. NFIL3 was highly-expressed in both peripheral blood neutrophils from gout patients and MSU-treated neutrophils. NFIL3 promoted the transcription of REDD1 by binding to its promoter. REDD1 augmented neutrophil autophagy and NET formation by inhibiting the mTOR pathway. In vivo experimental results further confirmed that silencing of NFIL3 reduced the inflammatory injury of acute gouty arthritis mice by inhibiting the neutrophil autophagy and NET formation, which was associated with down-regulation of REDD1 and activation of the mTOR pathway. Taken together, NFIL3 can aggravate the inflammatory reaction of gout by stimulating neutrophil autophagy and NET formation via REDD1/mTOR, highlighting NFIL3 as a potential therapeutic target for gout.

Downregulation of blood and bone marrow neutrophils decreases expression of acute lung injury in sheep

1992 ◽  
Vol 263 (5) ◽  
pp. H1492-H1498
Author(s):  
P. J. McKenna ◽  
D. L. Rosolia ◽  
Y. Ishihara ◽  
K. H. Albertine ◽  
N. C. Staub ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Lung Injury ◽  
Lung Injury ◽  
Peripheral Blood ◽  
Pulmonary Circulation ◽  
Tissue Injury ◽  
Blood Neutrophils ◽  
Superoxide Release

We have shown that infusion of zymosan-activated plasma (ZAP) in sheep causes acute lung injury and downregulates peripheral blood neutrophils in that elicited superoxide release is reduced for at least 24 h after the infusion. The present study was designed to test the following hypotheses: 1) peripheral blood neutrophils are representative of neutrophils marginated in the pulmonary circulation, 2) blood neutrophils are downregulated because neutrophils developing in bone marrow are similarly affected, and 3) downregulated neutrophils have a reduced capacity to produce tissue injury. In a series of experiments in 21 sheep, we showed that elicited superoxide release was similar in peripheral blood neutrophils and in marginated neutrophils washed out of the pulmonary vascular bed. Measurements of superoxide release from blood and bone marrow neutrophils collected 2-24 h after ZAP infusion revealed progressive downregulation with time and greater downregulation of superoxide release in bone marrow neutrophils compared with peripheral blood neutrophils. Finally, after downregulating peripheral blood neutrophils, subsequent infusion of ZAP in conscious sheep produced sequestration of neutrophils in the pulmonary circulation but failed to produce a sustained increase in lung lymph protein clearance. The results suggest that neutrophil downregulation, as measured in vitro, is expressed in vivo as reduced ability of neutrophils to produce tissue injury when challenged by an activating agent.

In Vivo Selection of Wild-Type Hematopoietic Stem Cells in a Murine Model of Fanconi Anemia

Blood ◽  
1999 ◽  
Vol 94 (6) ◽  
pp. 2151-2158 ◽  
Author(s):  
Kevin P. Battaile ◽  
Raynard L. Bateman ◽  
Derik Mortimer ◽  
Jean Mulcahy ◽  
R. Keaney Rathbun ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Hematopoietic Stem Cells ◽  
Fanconi Anemia ◽  
Peripheral Blood ◽  
Wild Type ◽  
Hematopoietic Stem ◽  
In Vivo Selection ◽  
Serial Transplantation

Fanconi anemia (FA) is an autosomal recessive disorder characterized by birth defects, increased incidence of malignancy, and progressive bone marrow failure. Bone marrow transplantation is therapeutic and, therefore, FA is a candidate disease for hematopoietic gene therapy. The frequent finding of somatic mosaicism in blood of FA patients has raised the question of whether wild-type bone marrow may have a selective growth advantage. To test this hypothesis, a cohort radio-ablated wild-type mice were transplanted with a 1:1 mixture of FA group C knockout (FACKO) and wild-type bone marrow. Analysis of peripheral blood at 1 month posttransplantation showed only a moderate advantage for wild-type cells, but upon serial transplantation, clear selection was observed. Next, a cohort of FACKO mice received a transplant of wild-type marrow cells without prior radio-ablation. No wild-type cells were detected in peripheral blood after transplantation, but a single injection of mitomycin C (MMC) resulted in an increase to greater than 25% of wild-type DNA. Serial transplantation showed that the selection occurred at the level of hematopoietic stem cells. No systemic side effects were observed. Our results show that in vivo selection for wild-type hematopoietic stem cells occurs in FA and that it is enhanced by MMC administration.

scholarly journals Novel protective role for MAP kinase phosphatase 2 in inflammatory arthritis

RMD Open ◽  
2019 ◽  
Vol 5 (1) ◽  
pp. e000711
Author(s):  
Juliane Schroeder ◽  
Kirsty Ross ◽  
Kathryn McIntosh ◽  
Shilan Jabber ◽  
Stuart Woods ◽  
...  
Keyword(s):  
Inflammatory Arthritis ◽  
Neutrophil Migration ◽  
Protective Role ◽  
Leukotriene B4 ◽  
Mitogen Activated Protein Kinase ◽  
Wild Type ◽  
Map Kinase Phosphatase ◽  
Tnf Α ◽  
The Impact

ObjectivesWe have previously shown mitogen-activated protein kinase phosphatase 2 (MKP-2) to be a key regulator of proinflammatory cytokines in macrophages. In the study presented here, we investigated the role of MKP-2 in inflammatory arthritis with a particular focus on neutrophils.MethodsTo achieve this, we subjected MKP-2 deficient and wild type mice to collagen antibody induced arthritis, an innate model of arthritis, and determined disease pathology. To further our investigation, we depleted neutrophils in a prophylactic and therapeutic fashion. Last, we used chemotaxis assays to analyse the impact of MKP-2 deletion on neutrophil migration.ResultsMKP-2-/- mice showed a significant increase in disease pathology linked to elevated levels of proarthritic cytokines and chemokines TNF-α, IL-6 and MCP-1 in comparison to wild type controls. This phenotype is prevented or abolished after administration of neutrophil depleting antibody prior or after onset of disease, respectively. While MCP-1 levels were not affected, neutrophil depletion diminished TNF-α and reduced IL-6, thus linking these cytokines to neutrophils. In vivo imaging showed that MKP-2-/- mice had an increased influx of neutrophils into affected joints, which was higher and potentially prolonged than in wild type animals. Furthermore, using chemotaxis assays we revealed that MKP-2 deficient neutrophils migrate faster towards a Leukotriene B4 gradient. This process correlated with a reduced phosphorylation of ERK in MKP-2-/- neutrophils.ConclusionsThis is the first study to show a protective role for MKP-2 in inflammatory arthritis.

scholarly journals Development and characterization of prototypes for in vitro and in vivo mouse models of ibrutinib-resistant CLL

2021 ◽  
Vol 5 (16) ◽  
pp. 3134-3146
Author(s):  
Burcu Aslan ◽  
Gorkem Kismali ◽  
Lisa S. Chen ◽  
LaKesla R. Iles ◽  
Mikhila Mahendra ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Overall Survival ◽  
Mouse Models ◽  
Cell Lines ◽  
Peripheral Blood ◽  
Survival Duration ◽  
Wild Type ◽  
In Vivo Models

Abstract Although ibrutinib improves the overall survival of patients with chronic lymphocytic leukemia (CLL), some patients still develop resistance, most commonly through point mutations affecting cysteine residue 481 (C481) in Bruton’s tyrosine kinase (BTKC481S and BTKC481R). To enhance our understanding of the biological impact of these mutations, we established cell lines that overexpress wild-type or mutant BTK in in vitro and in vivo models that mimic ibrutinib-sensitive and -resistant CLL. MEC-1 cell lines stably overexpressing wild-type or mutant BTK were generated. All cell lines coexpressed GFP, were CD19+ and CD23+, and overexpressed BTK. Overexpression of wild-type or mutant BTK resulted in increased signaling, as evidenced by the induction of p-BTK, p-PLCγ2, and p-extracellular signal–related kinase (ERK) levels, the latter further augmented upon IgM stimulation. In all cell lines, cell cycle profiles and levels of BTK expression were similar, but the RNA sequencing and reverse-phase protein array results revealed that the molecular transcript and protein profiles were distinct. To mimic aggressive CLL, we created xenograft mouse models by transplanting the generated cell lines into Rag2−/−γc−/− mice. Spleens, livers, bone marrow, and peripheral blood were collected. All mice developed CLL-like disease with systemic involvement (engraftment efficiency, 100%). We observed splenomegaly, accumulation of leukemic cells in the spleen and liver, and macroscopically evident necrosis. CD19+ cells accumulated in the spleen, bone marrow, and peripheral blood. The overall survival duration was slightly lower in mice expressing mutant BTK. Our cell lines and murine models mimicking ibrutinib-resistant CLL will serve as powerful tools to test reversible BTK inhibitors and novel, non–BTK-targeted therapeutics.

scholarly journals R1441G but not G201S mutation enhances LRRK2 mediated Rab10 phosphorylation in human peripheral blood neutrophils

2021 ◽  
Author(s):  
Ying Fan ◽  
Raja S. Nirujogi ◽  
Alicia Garrido ◽  
Javier Ruiz Martínez ◽  
Alberto Bergareche-Yarza ◽  
...  
Keyword(s):  
Peripheral Blood ◽  
Human Peripheral Blood ◽  
Treatment Strategies ◽  
Disease Status ◽  
Kinase Domain ◽  
G2019s Mutation ◽  
Mutation Carriers ◽  
Blood Neutrophils ◽  
Lrrk2 Kinase

AbstractGain-of kinase function variants in LRRK2 (leucine-rich repeat kinase 2) cause Parkinson’s disease (PD), albeit with incomplete and age-dependent penetrance, offering the prospect of disease-modifying treatment strategies via LRRK2 kinase inhibition. LRRK2 phosphorylates a subgroup of RabGTPases including Rab10 and pathogenic mutations enhance LRRK2-mediated phosphorylation of Rab10 at Thr73.In this study we analyse LRRK2 dependent Rab10Thr73 phosphorylation in human peripheral blood neutrophils isolated from 101 individuals using quantitative immunoblotting and mass spectrometry. Our cohort includes 42 LRRK2 mutation carriers (21 with the G2019S mutation that resides in the kinase domain and 21 with the R1441G mutation that lies within the ROC-COR domain), 27 patients with idiopathic PD, and 32 controls.We show that LRRK2 dependent Rab10 Thr73 phosphorylation is significantly elevated in all R1441G LRRKR2 mutation carriers irrespective of disease status. PD manifesting and non-manifesting G2019S mutation carriers as well as idiopathic PD samples did not display elevated Rab10 Thr73 phosphorylation. Furthermore, we analysed brain samples of 10 G2019S and 1 R1441H mutation carriers as well as 10 individuals with idiopathic PD and 10 controls. We find high variability for pRab10Thr73 phosphorylation amongst donors irrespective of genetic and disease state.We conclude that in vivo LRRK2 dependent pRab10Thr73 analysis in human peripheral blood neutrophils is a specific and robust biomarker for LRRK2 kinase activation for individuals with mutations such as R1441G that enhance pRab10Thr73 phosphorylation over 2-fold. We provide the first evidence that the LRRK2 R1441G mutation enhances LRRK2 kinase activity in a primary human cell.

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