scholarly journals Monocyte Regulation By Soluble Uric Acid

2021 ◽  
Author(s):  
◽  
René Joel McLaughlin
Keyword(s):  
Map Kinase ◽  
Human Blood ◽  
Nuclear Translocation ◽  
Blood Monocytes ◽  
Lps Challenge ◽  
Inflammatory Stimuli ◽  
Inflammatory Phenotype ◽  
Inflammatory Signalling

<p>Hyperuricaemia is a chronic condition associated with diseases of the metabolic syndrome. However, the cause and effect relationship between increased serum uric acid (UA) levels and the pathophysiology of metabolic dysfunction is far from clear. From an immunological angle hyperuricaemia has been shown to modulate inflammatory signalling in both immune and nonimmune cell types. Blood monocytes are constantly exposed to soluble UA in the circulation but the direct effect of this exposure has not been examined. This research focuses on the how soluble UA alters blood monocyte responses to inflammatory stimuli using in vitro, in vivo and clinical manipulation of UA levels. The Harper group previously found that blood monocytes from hyperuricaemic individuals produced lower levels of inflammatory cytokines compared to monocytes from healthy controls when stimulated ex vivo with LPS. My research began by studying the direct effect of soluble UA on human blood monocytes in vitro. I found that soluble UA reduced monocyte production of pro-inflammatory cytokines and increased IL-10 in response to stimulation with LPS. I identified two inflammatory signalling pathways modulated by soluble UA that could be contributing to this suppressive monocyte phenotype: MAP kinase phosphorylation was reduced alongside increased expression of the regulatory protein DUSP10 and reduced ASC; there was a switch towards anti-inflammatory NFκB signalling illustrated by decreased p65 and increased p50 nuclear translocation. To study the modulation of soluble UA levels in a physiological context I raised serum UA levels in vivo with a model of acute hyperuricaemia and lowered serum UA using two clinically relevant medications: allopurinol and rasburicase. Consistent with in vitro UA treatment, raising serum UA levels in vivo suppressed pro-inflammatory cytokine responses to LPS, increased IL-10 and down-regulated monocyte MAP kinase and NFκB signalling pathways. Acute urate-lowering therapy (ULT) with allopurinol or rasburicase reversed this suppressive inflammatory cytokine and signalling pattern. The PLT2 mouse strain has had the purine metabolic pathway disrupted by random mutagenesis of the gene encoding 5-hiydroxyisourate hydrolase, the enzyme responsible for degradation of the molecule directly downstream of UA, 5-hydroxyisourate. I found that this mutation resulted in chronic hyperuricaemia with an average 2-fold increase in serum UA over C57 mice. LPS challenge resulted in increased IL-10 production in PLT2 mice compared to C57, however no differences in monocyte inflammatory signalling were observed between the two strains. Acute ULT with rasburicase reduced serum UA in the PLT2 strain and subsequent LPS challenge increased monocyte inflammatory signalling. Finally, I studied the effects of ULT on the inflammatory phenotype of human blood monocytes from patients with hyperuricaemia. ULT significantly reduced serum UA levels, which coincided with reduced blood monocyte percentages and adhesion molecule expression (CD11b and ICAM1). ULT increased the inflammatory potential of human blood monocytes: Monocytes stimulated with LPS produced less IL-10; MAP kinase phosphorylation increased alongside increased ASC expression; nuclear translocation of NFκB p65 was increased. ULT also increased expression of the NLRP3 inflammasome components procaspase1, pro-IL-1β and NLRP3. Taken together these results demonstrate a previously unidentified role for soluble UA in moderating monocyte immune responses to inflammatory stimuli. In vitro, in vivo and clinical experimentation all confirmed the immunosuppressive function of soluble UA. This potentially places UA in the centre of innate immune control through the dichotomy of its suppressive soluble effects, demonstrated herein, and the widely reported inflammatory crystalline effects. Importantly, this research illustrates that serum UA levels can be manipulated in a clinical setting to control the inflammatory phenotype of circulating immune cells.</p>

scholarly journals Monocyte Regulation By Soluble Uric Acid

2021 ◽  
Author(s):  
◽  
René Joel McLaughlin
Keyword(s):  
Map Kinase ◽  
Human Blood ◽  
Nuclear Translocation ◽  
Blood Monocytes ◽  
Lps Challenge ◽  
Inflammatory Stimuli ◽  
Inflammatory Phenotype ◽  
Inflammatory Signalling

<p>Hyperuricaemia is a chronic condition associated with diseases of the metabolic syndrome. However, the cause and effect relationship between increased serum uric acid (UA) levels and the pathophysiology of metabolic dysfunction is far from clear. From an immunological angle hyperuricaemia has been shown to modulate inflammatory signalling in both immune and nonimmune cell types. Blood monocytes are constantly exposed to soluble UA in the circulation but the direct effect of this exposure has not been examined. This research focuses on the how soluble UA alters blood monocyte responses to inflammatory stimuli using in vitro, in vivo and clinical manipulation of UA levels. The Harper group previously found that blood monocytes from hyperuricaemic individuals produced lower levels of inflammatory cytokines compared to monocytes from healthy controls when stimulated ex vivo with LPS. My research began by studying the direct effect of soluble UA on human blood monocytes in vitro. I found that soluble UA reduced monocyte production of pro-inflammatory cytokines and increased IL-10 in response to stimulation with LPS. I identified two inflammatory signalling pathways modulated by soluble UA that could be contributing to this suppressive monocyte phenotype: MAP kinase phosphorylation was reduced alongside increased expression of the regulatory protein DUSP10 and reduced ASC; there was a switch towards anti-inflammatory NFκB signalling illustrated by decreased p65 and increased p50 nuclear translocation. To study the modulation of soluble UA levels in a physiological context I raised serum UA levels in vivo with a model of acute hyperuricaemia and lowered serum UA using two clinically relevant medications: allopurinol and rasburicase. Consistent with in vitro UA treatment, raising serum UA levels in vivo suppressed pro-inflammatory cytokine responses to LPS, increased IL-10 and down-regulated monocyte MAP kinase and NFκB signalling pathways. Acute urate-lowering therapy (ULT) with allopurinol or rasburicase reversed this suppressive inflammatory cytokine and signalling pattern. The PLT2 mouse strain has had the purine metabolic pathway disrupted by random mutagenesis of the gene encoding 5-hiydroxyisourate hydrolase, the enzyme responsible for degradation of the molecule directly downstream of UA, 5-hydroxyisourate. I found that this mutation resulted in chronic hyperuricaemia with an average 2-fold increase in serum UA over C57 mice. LPS challenge resulted in increased IL-10 production in PLT2 mice compared to C57, however no differences in monocyte inflammatory signalling were observed between the two strains. Acute ULT with rasburicase reduced serum UA in the PLT2 strain and subsequent LPS challenge increased monocyte inflammatory signalling. Finally, I studied the effects of ULT on the inflammatory phenotype of human blood monocytes from patients with hyperuricaemia. ULT significantly reduced serum UA levels, which coincided with reduced blood monocyte percentages and adhesion molecule expression (CD11b and ICAM1). ULT increased the inflammatory potential of human blood monocytes: Monocytes stimulated with LPS produced less IL-10; MAP kinase phosphorylation increased alongside increased ASC expression; nuclear translocation of NFκB p65 was increased. ULT also increased expression of the NLRP3 inflammasome components procaspase1, pro-IL-1β and NLRP3. Taken together these results demonstrate a previously unidentified role for soluble UA in moderating monocyte immune responses to inflammatory stimuli. In vitro, in vivo and clinical experimentation all confirmed the immunosuppressive function of soluble UA. This potentially places UA in the centre of innate immune control through the dichotomy of its suppressive soluble effects, demonstrated herein, and the widely reported inflammatory crystalline effects. Importantly, this research illustrates that serum UA levels can be manipulated in a clinical setting to control the inflammatory phenotype of circulating immune cells.</p>

scholarly journals Expression of LAIR-1 (CD305) on Human Blood Monocytes as a Marker of Hepatic Cirrhosis Progression

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
María Martínez-Esparza ◽  
Antonio José Ruiz-Alcaraz ◽  
Violeta Carmona-Martínez ◽  
María Dolores Fernández-Fernández ◽  
Gonzalo Antón ◽  
...  
Keyword(s):  
Liver Cirrhosis ◽  
Cell Surface ◽  
Human Blood ◽  
Total Content ◽  
Cell Surface Expression ◽  
Human Macrophage ◽  
Blood Monocytes ◽  
Cirrhotic Patients

Background and Aim. The presumed role of the inhibitory receptor LAIR-1 (CD305) in the inflammatory response suggests that it might contribute to the pathophysiology of chronic inflammatory diseases such as liver cirrhosis. We studied the LAIR-1 expression on liver macrophages and blood monocytes related to the progression of liver cirrhosis. Methods. The expression of LAIR-1 was analyzed by immunohistochemistry, flow cytometry, and Western blot. Results. We found a decreased number of macrophages expressing LAIR-1 in cirrhotic liver that could be due to a high presence of collagen, ligand of LAIR-1, in the fibrotic tissue which could downregulate its expression or interfere with the immunostaining. The expression of LAIR-1 decreased after cell differentiation, and the total content, but not the cell surface expression, increased after activation in the HL-60 human macrophage in vitro model. Blood monocytes exhibited higher LAIR-1 expression levels in cirrhotic patients, which were evident even in early clinical stages in all monocyte subsets, and greater in the “intermediate” inflammatory monocyte subpopulation. The in vitro activation of human blood monocytes did not increase its expression on the cell surface suggesting that the in vivo increase of LAIR-1 must be the result of a specific combination of stimuli present in cirrhotic patients. This represents an exclusive feature of liver cirrhosis, since blood monocytes from other chronic inflammatory pathologies showed similar or lower LAIR-1 levels compared with those of healthy controls. Conclusions. These results may indicate that monocyte LAIR-1 expression is a new biomarker to early detect liver damage caused by chronic inflammation in liver cirrhosis.

scholarly journals Sectm1a deficiency aggravates inflammation-triggered cardiac dysfunction through disruption of LXRα signalling in macrophages

2020 ◽  
Author(s):  
Yutian Li ◽  
Shan Deng ◽  
Xiaohong Wang ◽  
Wei Huang ◽  
Jing Chen ◽  
...  
Keyword(s):  
Inflammatory Cytokines ◽  
Cardiac Dysfunction ◽  
Nuclear Translocation ◽  
Inflammatory Responses ◽  
Transmembrane Protein ◽  
Bioinformatics Analyses ◽  
Lps Challenge ◽  
Inflammatory Monocytes

Abstract Aims Cardiac dysfunction is a prevalent comorbidity of disrupted inflammatory homeostasis observed in conditions such as sepsis (acute) or obesity (chronic). Secreted and transmembrane protein 1a (Sectm1a) has previously been implicated to regulate inflammatory responses, yet its role in inflammation-associated cardiac dysfunction is virtually unknown. Methods and results Using the CRISPR/Cas9 system, we generated a global Sectm1a-knockout (KO) mouse model and observed significantly increased mortality and cardiac injury after lipopolysaccharide (LPS) injection, when compared with wild-type (WT) control. Further analysis revealed significantly increased accumulation of inflammatory macrophages in hearts of LPS-treated KO mice. Accordingly, ablation of Sectm1a remarkably increased inflammatory cytokines levels both in vitro [from bone marrow-derived macrophages (BMDMs)] and in vivo (in serum and myocardium) after LPS challenge. RNA-sequencing results and bioinformatics analyses showed that the most significantly down-regulated genes in KO-BMDMs were modulated by LXRα, a nuclear receptor with robust anti-inflammatory activity in macrophages. Indeed, we identified that the nuclear translocation of LXRα was disrupted in KO-BMDMs when treated with GW3965 (LXR agonist), resulting in higher levels of inflammatory cytokines, compared to GW3965-treated WT-cells. Furthermore, using chronic inflammation model of high-fat diet (HFD) feeding, we observed that infiltration of inflammatory monocytes/macrophages into KO-hearts were greatly increased and accordingly, worsened cardiac function, compared to WT-HFD controls. Conclusion This study defines Sectm1a as a new regulator of inflammatory-induced cardiac dysfunction through modulation of LXRα signalling in macrophages. Our data suggest that augmenting Sectm1a activity may be a potential therapeutic approach to resolve inflammation and associated cardiac dysfunction.

scholarly journals Extracellular forms of IL-37 inhibit innate inflammation in vitro and in vivo but require the IL-1 family decoy receptor IL-1R8

2015 ◽  
Vol 112 (8) ◽  
pp. 2497-2502 ◽  
Author(s):  
Suzhao Li ◽  
C. Preston Neff ◽  
Kristina Barber ◽  
Jaewoo Hong ◽  
Yuchun Luo ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
Human Blood ◽  
Fold Increase ◽  
Surface Expression ◽  
Mouse Bone Marrow ◽  
Mrna Levels ◽  
Blood Monocytes ◽  
Decoy Receptor

Similar to IL-1α and IL-33, IL-1 family member IL-37b translocates to the nucleus and is associated with suppression of innate and adaptive immunity. Here we demonstrate an extracellular function of the IL-37 precursor and a processed form. Recombinant IL-37 precursor reduced LPS-induced IL-6 by 50% (P < 0.001) in highly inflammatory human blood-derived M1 differentiated macrophages derived from selective subjects but not M2 macrophages. In contrast, a neutralizing monoclonal anti–IL-37 increased LPS-induced IL-6, TNFα and IL-1β (P < 0.01). The suppression by IL-37 was consistently observed at low picomolar but not nanomolar concentrations. Whereas LPS induced a 12-fold increase in TNFα mRNA, IL-37 pretreatment decreased the expression to only 3-fold over background (P < 0.01). Mechanistically, LPS-induced p38 and pERK were reduced by IL-37. Recombinant IL-37 bound to the immobilized ligand binding α-chain of the IL-18 receptor as well as to the decoy receptor IL-1R8. In M1 macrophages, LPS increased the surface expression of IL-1R8. Compared with human blood monocytes, resting M1 cells express more surface IL-1R8 as well as total IL-1R8; there was a 16-fold increase in IL-1R8 mRNA levels when pretreated with IL-37. IL-37 reduced LPS-induced TNFα and IL-6 by 50–55% in mouse bone marrow-derived dendritic cells, but not in dendritic cells derived from IL-1R8–deficient mice. In mice subjected to systemic LPS-induced inflammation, pretreatment with IL-37 reduced circulating and organ cytokine levels. Thus, in addition to a nuclear function, IL-37 acts as an extracellular cytokine by binding to the IL-18 receptor but using the IL-1R8 for its anti-inflammatory properties.

scholarly journals Functional and Transcriptional Adaptations of Blood Monocytes Recruited to the Cystic Fibrosis Airway Microenvironment In Vitro

2021 ◽  
Vol 22 (5) ◽  
pp. 2530
Author(s):  
Bijean D. Ford ◽  
Diego Moncada Giraldo ◽  
Camilla Margaroli ◽  
Vincent D. Giacalone ◽  
Milton R. Brown ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Bactericidal Activity ◽  
Scavenger Receptor ◽  
Receptor Expression ◽  
Blood Monocytes ◽  
Bacterial Killing ◽  
Blood Neutrophils ◽  
Vitro Model

Cystic fibrosis (CF) lung disease is dominated by the recruitment of myeloid cells (neutrophils and monocytes) from the blood which fail to clear the lung of colonizing microbes. In prior in vitro studies, we showed that blood neutrophils migrated through the well-differentiated lung epithelium into the CF airway fluid supernatant (ASN) mimic the dysfunction of CF airway neutrophils in vivo, including decreased bactericidal activity despite an increased metabolism. Here, we hypothesized that, in a similar manner to neutrophils, blood monocytes undergo significant adaptations upon recruitment to CFASN. To test this hypothesis, primary human blood monocytes were transmigrated in our in vitro model into the ASN from healthy control (HC) or CF subjects to mimic in vivo recruitment to normal or CF airways, respectively. Surface phenotype, metabolic and bacterial killing activities, and transcriptomic profile by RNA sequencing were quantified post-transmigration. Unlike neutrophils, monocytes were not metabolically activated, nor did they show broad differences in activation and scavenger receptor expression upon recruitment to the CFASN compared to HCASN. However, monocytes recruited to CFASN showed decreased bactericidal activity. RNASeq analysis showed strong effects of transmigration on monocyte RNA profile, with differences between CFASN and HCASN conditions, notably in immune signaling, including lower expression in the former of the antimicrobial factor ISG15, defensin-like chemokine CXCL11, and nitric oxide-producing enzyme NOS3. While monocytes undergo qualitatively different adaptations from those seen in neutrophils upon recruitment to the CF airway microenvironment, their bactericidal activity is also dysregulated, which could explain why they also fail to protect CF airways from infection.

scholarly journals Inhibition of RANKL-Induced Osteoclastogenesis by Novel Mutant RANKL

2021 ◽  
Vol 22 (1) ◽  
pp. 434
Author(s):  
Yuria Jang ◽  
Hong Moon Sohn ◽  
Young Jong Ko ◽  
Hoon Hyun ◽  
Wonbong Lim
Keyword(s):  
Nuclear Translocation ◽  
Critical Role ◽  
Osteoclast Differentiation ◽  
Point Mutations ◽  
Tartrate Resistant Acid Phosphatase ◽  
Mice Model ◽  
Gsk 3Β ◽  
Rank Signaling

Background: Recently, it was reported that leucine-rich repeat-containing G-protein-coupled receptor 4 (LGR4, also called GPR48) is another receptor for RANKL and was shown to compete with RANK to bind RANKL and suppress canonical RANK signaling during osteoclast differentiation. The critical role of the protein triad RANK–RANKL in osteoclastogenesis has made their binding an important target for the development of drugs against osteoporosis. In this study, point-mutations were introduced in the RANKL protein based on the crystal structure of the RANKL complex and its counterpart receptor RANK, and we investigated whether LGR4 signaling in the absence of the RANK signal could lead to the inhibition of osteoclastogenesis.; Methods: The effects of point-mutated RANKL (mRANKL-MT) on osteoclastogenesis were assessed by tartrate-resistant acid phosphatase (TRAP), resorption pit formation, quantitative real-time polymerase chain reaction (qPCR), western blot, NFATc1 nuclear translocation, micro-CT and histomorphological assay in wild type RANKL (mRANKL-WT)-induced in vitro and in vivo experimental mice model. Results: As a proof of concept, treatment with the mutant RANKL led to the stimulation of GSK-3β phosphorylation, as well as the inhibition of NFATc1 translocation, mRNA expression of TRAP and OSCAR, TRAP activity, and bone resorption, in RANKL-induced mouse models; and Conclusions: The results of our study demonstrate that the mutant RANKL can be used as a therapeutic agent for osteoporosis by inhibiting RANKL-induced osteoclastogenesis via comparative inhibition of RANKL. Moreover, the mutant RANKL was found to lack the toxic side effects of most osteoporosis treatments.

scholarly journals Phaseolin Attenuates Lipopolysaccharide-Induced Inflammation in RAW 264.7 Cells and Zebrafish

Biomedicines ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 420
Author(s):  
Su-Jung Hwang ◽  
Ye-Seul Song ◽  
Hyo-Jong Lee
Keyword(s):  
Nitric Oxide ◽  
Nuclear Translocation ◽  
Raw 264.7 Cells ◽  
Network Pharmacology ◽  
Raw 264.7 ◽  
Dependent Manner ◽  
Bioactive Constituents

Kushen (Radix Sophorae flavescentis) is used to treat ulcerative colitis, tumors, and pruritus. Recently, phaseolin, formononetin, matrine, luteolin, and quercetin, through a network pharmacology approach, were tentatively identified as five bioactive constituents responsible for the anti-inflammatory effects of S. flavescentis. However, the role of phaseolin (one of the primary components of S. flavescentis) in the direct regulation of inflammation and inflammatory processes is not well known. In this study, the beneficial role of phaseolin against inflammation was explored in lipopolysaccharide (LPS)-induced inflammation models of RAW 264.7 macrophages and zebrafish larvae. Phaseolin inhibited LPS-mediated production of nitric oxide (NO) and the expression of inducible nitric oxide synthase (iNOS), without affecting cell viability. In addition, phaseolin suppressed pro-inflammatory mediators such as cyclooxygenase 2 (COX-2), interleukin-1β (IL-1β), tumor necrosis factor α (TNF-α), monocyte chemoattractant protein-1 (MCP-1), and interleukin-6 (IL-6) in a dose-dependent manner. Furthermore, phaseolin reduced matrix metalloproteinase (MMP) activity as well as macrophage adhesion in vitro and the recruitment of leukocytes in vivo by downregulating Ninjurin 1 (Ninj1), an adhesion molecule. Finally, phaseolin inhibited the nuclear translocation of nuclear factor-kappa B (NF-κB). In view of the above, our results suggest that phaseolin could be a potential therapeutic candidate for the management of inflammation.

scholarly journals LINGO-1 shRNA protects the brain against ischemia/reperfusion injury by inhibiting the activation of NF-κB and JAK2/STAT3

Human Cell ◽  
2021 ◽  
Author(s):  
Jiaying Zhu ◽  
Zhu Zhu ◽  
Yipin Ren ◽  
Yukang Dong ◽  
Yaqi Li ◽  
...  
Keyword(s):  
Cerebral Ischemia ◽  
Nuclear Translocation ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Glucose Deprivation ◽  
Artery Occlusion ◽  
Mice Model ◽  
Down Regulation

AbstractLINGO-1 may be involved in the pathogenesis of cerebral ischemia. However, its biological function and underlying molecular mechanism in cerebral ischemia remain to be further defined. In our study, middle cerebral artery occlusion/reperfusion (MACO/R) mice model and HT22 cell oxygen–glucose deprivation/reperfusion (OGD/R) were established to simulate the pathological process of cerebral ischemia in vivo and in vitro and to detect the relevant mechanism. We found that LINGO-1 mRNA and protein were upregulated in mice and cell models. Down-regulation LINGO-1 improved the neurological symptoms and reduced pathological changes and the infarct size of the mice after MACO/R. In addition, LINGO-1 interference alleviated apoptosis and promoted cell proliferation in HT22 of OGD/R. Moreover, down-regulation of LINGO-1 proved to inhibit nuclear translocation of p-NF-κB and reduce the expression level of p-JAK2 and p-STAT3. In conclusion, our data suggest that shLINGO-1 attenuated ischemic injury by negatively regulating NF-KB and JAK2/STAT3 pathways, highlighting a novel therapeutic target for ischemic stroke.

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