scholarly journals Intracellular NAD+ Depletion Confers a Priming Signal for NLRP3 Inflammasome Activation

2021 ◽  
Vol 12 ◽  
Author(s):  
Do-Wan Shim ◽  
Hyo-Joung Cho ◽  
Inhwa Hwang ◽  
Taek-Yeol Jung ◽  
Hyun-Seok Kim ◽  
...  
Keyword(s):  
Nlrp3 Inflammasome ◽  
Specific Inhibitor ◽  
Retrograde Transport ◽  
Poly I:C ◽  
Inflammasome Activation ◽  
Mouse Bone Marrow ◽  
Caspase 1 ◽  
Nicotinamide Mononucleotide ◽  
Nlrp3 Inflammasome Activation

Nicotinamide adenine dinucleotide (NAD+) is an important cofactor in many redox and non-redox NAD+-consuming enzyme reactions. Intracellular NAD+ level steadily declines with age, but its role in the innate immune potential of myeloid cells remains elusive. In this study, we explored whether NAD+ depletion by FK866, a highly specific inhibitor of the NAD salvage pathway, can affect pattern recognition receptor-mediated responses in macrophages. NAD+-depleted mouse bone marrow-derived macrophages (BMDMs) exhibited similar levels of proinflammatory cytokine production in response to LPS or poly (I:C) stimulation compared with untreated cells. Instead, FK866 facilitated robust caspase-1 activation in BMDMs in the presence of NLRP3-activating signals such as ATP and nigericin, a potassium ionophore. However, this FK866-mediated caspase-1 activation was completely abolished in Nlrp3-deficient macrophages. FK866 plus nigericin stimulation caused an NLRP3-dependent assembly of inflammasome complex. In contrast, restoration of NAD+ level by supplementation with nicotinamide mononucleotide abrogated the FK866-mediated caspase-1 cleavage. FK866 did not induce or increase the expression levels of NLRP3 and interleukin (IL)-1β but drove mitochondrial retrograde transport into the perinuclear region. FK866-nigericin-induced mitochondrial transport is critical for caspase-1 cleavage in macrophages. Consistent with the in vitro experiments, intradermal coinjection of FK866 and ATP resulted in robust IL-1β expression and caspase-1 activation in the skin of wild-type, but not Nlrp3-deficient mice. Collectively, our data suggest that NAD+ depletion provides a non-transcriptional priming signal for NLRP3 activation via mitochondrial perinuclear clustering, and aging-associated NAD+ decline can trigger NLRP3 inflammasome activation in ATP-rich environments.

scholarly journals The Essential Oil of Artemisia argyi H.Lév. and Vaniot Attenuates NLRP3 Inflammasome Activation in THP-1 Cells

2021 ◽  
Vol 12 ◽  
Author(s):  
Pengxiao Chen ◽  
Qi Bai ◽  
Yanting Wu ◽  
Qiongzhen Zeng ◽  
Xiaowei Song ◽  
...  
Keyword(s):  
Essential Oil ◽  
Nlrp3 Inflammasome ◽  
Therapeutic Potential ◽  
Inflammasome Activation ◽  
Caspase 1 ◽  
Artemisia Argyi ◽  
Nlrp3 Inflammasome Activation ◽  
Long Time

Artemisia argyi H. Lév. and Vaniot is a traditional medical herb that has been used for a long time in China and other Asian counties. Essential oil is the main active fraction of Artemisia argyi H. Lév. and Vaniot, and its anti-inflammatory potential has been observed in vitro and in vivo. Here, we found that the essential oil of Artemisia argyi H. Lév. and Vaniot (EOAA) inhibited monosodium urate (MSU)- and nigericin-induced NLRP3 inflammasome activation. EOAA suppressed caspase-1 and IL-1β processing and pyroptosis. NF-κB p65 phosphorylation and translocation were also inhibited. In addition, EOAA suppressed nigericin-induced NLRP3 inflammasome activation without blocking ASC oligomerization, suggesting that it may inhibit NLRP3 inflammasome activation by preventing caspase-1 processing. Our study thus indicates that EOAA inhibits NLRP3 inflammasome activation and has therapeutic potential against NLRP3-driven diseases.

scholarly journals Astragaloside IV Suppresses High Glucose-Induced NLRP3 Inflammasome Activation by Inhibiting TLR4/NF-κB and CaSR

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Bin Leng ◽  
Yingjie Zhang ◽  
Xinran Liu ◽  
Zhen Zhang ◽  
Yang Liu ◽  
...  
Keyword(s):  
Nlrp3 Inflammasome ◽  
High Glucose ◽  
Inflammasome Activation ◽  
Astragaloside Iv ◽  
Caspase 1 ◽  
Endothelial Inflammation ◽  
Nlrp3 Inflammasome Activation ◽  
Anti Inflammatory

Long-term exposure to high glucose induces vascular endothelial inflammation that can result in cardiovascular disease. Astragaloside IV (As-IV) is widely used for anti-inflammatory treatment of cardiovascular diseases. However, its mechanism of action is still not fully understood. In this study, we investigated the effect of As-IV on high glucose-induced endothelial inflammation and explored its possible mechanisms. In vivo, As-IV (40 and 80 mg/kg/d) was orally administered to rats for 8 weeks after a single intraperitoneal injection of streptozotocin (STZ, 65 mg/kg). In vitro, human umbilical vein endothelial cells (HUVECs) were treated with high glucose (33 mM glucose) in the presence or absence of As-IV, NPS2143 (CaSR inhibitor), BAY 11-7082 (NF-κB p65 inhibitor), and INF39 (NLRP3 inhibitor), and overexpression of CaSR was induced by infection of CaSR-overexpressing lentiviral vectors to further discuss the anti-inflammatory property of As-IV. The results showed that high glucose increased the expression of interleukin-18 (IL-18), interleukin-1β (IL-1β), NLRP3, caspase-1, and ASC, as well as the protein level of TLR4, nucleus p65, and CaSR. As-IV can reverse these changes in vivo and in vitro. Meanwhile, NPS2143, BAY 11-7082, and INF39 could significantly abolish the high glucose-enhanced NLRP3, ASC, caspase-1, IL-18, and IL-1β expression in vitro. In addition, both NPS2143 and BAY 11-7082 attenuated high glucose-induced upregulation of NLRP3, ASC, caspase-1, IL-18, and IL-1β expression. In conclusion, this study suggested that As-IV could inhibit high glucose-induced NLRP3 inflammasome activation and subsequent secretion of proinflammatory cytokines via inhibiting TLR4/NF-κB signaling pathway and CaSR, which provides new insights into the anti-inflammatory activity of As-IV.

scholarly journals Stavudine Reduces NLRP3 Inflammasome Activation and Upregulates Aβ-Autophagy

2018 ◽  
Author(s):  
Francesca La Rosa ◽  
Marina Saresella ◽  
Ivana Marventano ◽  
Federica Piancone ◽  
Enrico Ripamonti ◽  
...  
Keyword(s):  
Nlrp3 Inflammasome ◽  
Inflammasome Activation ◽  
Clinical Scenario ◽  
Rt Pcr ◽  
Reverse Transcriptase Inhibitors ◽  
Beneficial Effects ◽  
Caspase 1 ◽  
Nlrp3 Inflammasome Activation ◽  
Aβ Clearance

AbstractAlzheimer’s disease (AD) is associated with amyloid-beta (Aβ) deposition and neuroinflammation, possibly driven by activation of the NLRP3 inflammasome. Nucleoside reverse transcriptase inhibitors (NRTI) hamper the assembly of the NLRP3 inflammasome; we analyzed whether stavudine (D4T), a prototypical NRTI, modulates Aβ-mediated inflammasome activation; because neuroinflammation impairs Aβ clearance by phagocytes, phagocytosis and autophagy were examined as well. THP-1-derived macrophages were stimulated in vitro with Aβ42 alone or after LPS priming with/without D4T. NLRP3 and TREM2 expression was analyzed by RT-PCR, phagocytosis and ASC-Speck by AmnisFlowSight, NLRP3-produced cytokines by ELISA, authophagy by P-ELISA evaluation of P-ERK and P-AKT. Results showed that IL1β, IL18 and caspase-1 were increased whereas Aβ-phagocytosis and TREM2 were reduced in LPS+Aβ42-stimulated cells. D4T reduced NLRP3 assembly as well as IL18 and caspase-1 production, but not IL1β, phagocytosis, and TREM2. P-AKT expression was augmented and P-ERK was reduced by D4T, suggesting a stimulatory effect on autophagy. D4T reduces NLRP3 inflammasome-associated inflammation, possibly restoring autophagy, in an in vitro model of AD; it will be interesting to verify its possibly beneficial effects in the clinical scenario.

scholarly journals Bruton’s tyrosine kinase drives neuroinflammation and anxiogenic behavior in mouse models of stress

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Simantini Ghosh ◽  
Zaidan Mohammed ◽  
Itender Singh
Keyword(s):  
Mouse Models ◽  
Peripheral Blood Mononuclear Cells ◽  
Nlrp3 Inflammasome ◽  
Peripheral Blood ◽  
Mononuclear Cells ◽  
Specific Inhibitor ◽  
Inflammasome Activation ◽  
Peripheral Blood Mononuclear ◽  
Caspase 1 ◽  
Nlrp3 Inflammasome Activation

Abstract Background Current therapies targeting several neurotransmitter systems are only able to partially mitigate the symptoms of stress- and trauma-related disorder. Stress and trauma-related disorders lead to a prominent inflammatory response in humans, and in pre-clinical models. However, mechanisms underlying the induction of neuroinflammatory response in PTSD and anxiety disorders are not clearly understood. The present study investigated the mechanism underlying the activation of proinflammatory NLRP3 inflammasome and IL1β in mouse models of stress. Methods We used two mouse models of stress, i.e., mice subjected to physical restraint stress with brief underwater submersion, and predator odor stress. Mice were injected with MCC950, a small molecule specific inhibitor of NLRP3 activation. To pharmacologically inhibit BTK, a specific inhibitor ibrutinib was used. To validate the observation from ibrutinib studies, a separate group of mice was injected with another BTK-specific inhibitor LFM-A13. Seven days after the induction of stress, mice were examined for anxious behavior using open field test (OFT), light–dark test (LDT), and elevated plus maze test (EPM). Following the behavior tests, hippocampus and amygdale were extracted and analyzed for various components of NLRP3–caspase 1–IL1β pathway. Plasma and peripheral blood mononuclear cells were also used to assess the induction of NLRP3–Caspase 1–IL-1β pathway in stressed mice. Results Using two different pre-clinical models of stress, we demonstrate heightened anxious behavior in female mice as compared to their male counterparts. Stressed animals exhibited upregulation of proinflammatory IL1β, IL-6, Caspase 1 activity and NLRP3 inflammasome activation in brain, which were significantly higher in female mice. Pharmacological inhibition of NLRP3 inflammasome activation led to anxiolysis as well as attenuated neuroinflammatory response. Further, we observed induction of activated Bruton’s tyrosine kinase (BTK), an upstream positive-regulator of NLRP3 inflammasome activation, in hippocampus and amygdala of stressed mice. Next, we conducted proof-of-concept pharmacological BTK inhibitor studies with ibrutinib and LFM-A13. In both sets of experiments, we found BTK inhibition led to anxiolysis and attenuated neuroinflammation, as indicated by significant reduction of NLRP3 inflammasome and proinflammatory IL-1β in hippocampus and amygdala. Analysis of plasma and peripheral blood mononuclear cells indicated peripheral induction of NLRP3–caspase 1–IL1β pathway in stressed mice. Conclusion Our study identified BTK as a key upstream regulator of neuroinflammation, which drives anxiogenic behavior in mouse model of stress. Further, we demonstrated the sexually divergent activation of BTK, providing a clue to heightened neuroinflammation and anxiogenic response to stress in females as compared to their male counterparts. Our data from the pharmacological inhibition studies suggest BTK as a novel target for the development of potential clinical treatment of PTSD and anxiety disorders. Induction of pBTK and NLRP3 in peripheral blood mononuclear cells of stressed mice suggest the potential effect of stress on systemic inflammation.

scholarly journals Role of ASM/Cer/TXNIP signaling module in the NLRP3 inflammasome activation

2020 ◽  
Author(s):  
Jianjun Jiang ◽  
Jin Yang ◽  
Yining Shi ◽  
Jiyu Cao ◽  
Youjin Lu ◽  
...  
Keyword(s):  
Nlrp3 Inflammasome ◽  
Underlying Mechanism ◽  
Acid Sphingomyelinase ◽  
Receptor Protein ◽  
Inflammasome Activation ◽  
Mrna Levels ◽  
Caspase 1 ◽  
Nlrp3 Inflammasome Activation

Abstract Background: The NOD-Like Receptor Protein 3 (NLRP3) inflammasome is a crucial component of an array of inflammatory conditions. It functions by boosting the secretion of pro-inflammatory cytokines: interleukin-1β (IL-1β) and interleukin-18 (IL-18). Previous studies have established the vital role of the acid sphingomyelinase (ASM)/ceramide (Cer) pathway in the functional outcome of cells, with a particular emphasis on the inflammatory processes. This study aimed to explore the effects and associated underlying mechanism of Cer-induced NLRP3 inflammasome activation.Methods: Lipopolysaccharide (LPS)/adenosine triphosphate (ATP)-induced NLRP3 inflammasome activation in J774A.1 cells was used as an in vitro inflammatory model. Western blotting and Real-time PCR (RT-PCR) were used to detect the protein and mRNA levels, respectively. IL-1β and IL-18 levels were evaluated using ELISA kits. ASM assay kit and immunofluorescence were used to detect ASM activity and Cer content.Results: Imipramine, a well-known inhibitor of ASM, significantly inhibited ASM activity and inhibited Cer accumulation, which indicated ASM activation. Besides, it also suppressed the LPS/ATP-induced expression of proteins and mRNA: thioredoxin interacting protein (TXNIP), NLRP3, caspase-1, IL-1β and IL-18. Interestingly verapamil, a TXNIP inhibitor, suppressed LPS/ATP-induced TXNIP/NLRP3 inflammasome activation; however, it did not affect LPS/ATP-induced ASM activation and ceramide production. Further analysis showed that the exogenous C2-Cer treated J774A.1 cells induced the overexpression of TXNIP, NLRP3, caspase-1, IL-1β and IL-18. Besides, TXNIP siRNA or verapamil inhibited C2-Cer-induced TXNIP overexpression and NLRP3 inflammasome activation.Conclusion: This study demonstrated the involvement of the ASM/Cer/TXNIP signaling pathway in NLRP3 inflammasome activation.

scholarly journals Red Raspberry Polyphenols Reduce the High Fat Diet-driven Adipocyte Hypertrophy by Suppressing NLRP3 Inflammasome Activation (P08-028-19)

2019 ◽  
Vol 3 (Supplement_1) ◽  
Author(s):  
Rong Fan ◽  
Ashley Toney ◽  
David Giraud ◽  
Mikyoung You ◽  
Judy Kim ◽  
...  
Keyword(s):  
Nlrp3 Inflammasome ◽  
Stromal Vascular Fraction ◽  
Inflammasome Activation ◽  
Reporter Assay ◽  
Adipocyte Size ◽  
Red Raspberry ◽  
Caspase 1 ◽  
Nlrp3 Inflammasome Activation ◽  
Adipocyte Hypertrophy

Abstract Objectives NLRP3 inflammasome is an innate immune machinery for caspase-1 cleavage and IL-1β secretion. Activation of the NLRP3 inflammasome is a metabolic culprit linking adipose inflammation to systemic metabolic dysfunction. Red raspberry (RR) is rich in polyphenols shown to exert protective role against obesity and metabolic syndrome. This study aimed to investigate the impact of RR polyphenols on activation of NLRP3 inflammasome and its metabolic benefits. Methods The whole, seed, and pulp RR polyphenols were fractionated and lyophilized. C57BL/6 male mice were assigned 1 of 5 diets of LF (10% total calorie from fat), HF (45% calorie from fat), or HF diet containing RR polyphenols from whole (0.4%), pulp (0.3%) and seed (0.1%) fraction for 12 weeks. Macrophage infiltration and NLRP3 inflammasome activation were determined by macrophage signature gene/protein expression and caspase-1 cleavage in the epididymal fat and stromal vascular fraction. Adipogenic potential was evaluated by epigenetic marks of H3K27Ac in the stromal vascular fraction. IL-1β reporter assay was used to validate the NLRP3 inflammasome activation in vitro. To explore the paracrine effects of IL-1β in regulating adipogenesis, we designed the conditioned medium experiments between macrophages and C3H10T1/2 murine pluripotent stem cells. Results The whole and pulp, but not seed, RR polyphenols significantly reduced the HF-driven weight gain, dyslipidemia, and insulin resistance. Whole or pulp RR polyphenols decreased inflammation, macrophage recruitment, and adipocyte size in epididymal fat compared to HF alone or seed polyphenols. Reduced adipocyte size by whole and pulp polyphenols was linked with 1) reduced NLRP3 inflammasome in the stromal vascular fraction, evidenced by reduced IκBα degradation and caspase-1 cleavage, and 2) augmented new fat cell formation via epigenetic modifications for adipogenesis (i.e., H3K27Ac, H3K9Ac, and H3K4m2). Supporting these in vivo results, RR polyphenol treatment in macrophages not only attenuated IL-1β reporter assay but also reversed the paracrine action of IL-1β in blocking adipogenesis in vitro. Conclusions Blocking NLRP3 by RR polyphenols is a promising dietary intervention strategy to promote healthy adipose remodeling, preventing adipocyte hypertrophy, fatty acid spillover, and further metabolic complications. Funding Sources USDA NIFA.

scholarly journals The E3 Ubiquitin Ligase TRIM65 Negatively Regulates Inflammasome Activation Through Promoting Ubiquitination of NLRP3

2021 ◽  
Vol 12 ◽  
Author(s):  
Tiantian Tang ◽  
Ping Li ◽  
Xinhui Zhou ◽  
Rui Wang ◽  
Xiuqin Fan ◽  
...  
Keyword(s):  
Nlrp3 Inflammasome ◽  
Inflammatory Diseases ◽  
Critical Role ◽  
Neutrophil Migration ◽  
Inflammasome Activation ◽  
Regulation Mechanism ◽  
Caspase 1 ◽  
Nlrp3 Inflammasome Activation

The dysregulation of NLRP3 inflammasome plays a critical role in pathogenesis of various human inflammatory diseases, thus NLRP3 inflammasome activation must be tightly controlled at multiple levels. However, the underlying mechanism regulating NLRP3 inflammasome activation remains unclear. Herein, the effects of Tripartite motif-containing protein 65 (TRIM65) on NLRP3 inflammasome activation and the underlying molecular mechanism were investigated in vitro and in vivo. Inhibition or deletion of Trim65 could significantly strengthen agonist induced NLRP3 inflammasome activation in THP-1 cells and BMDMs, indicated by increased caspase-1 activation and interleukin-1β secretion. However, TRIM65 had no effect on poly (dA: dT)-induced AIM2 inflammasome activation or flagellin-induced IPAF inflammasome activation. Mechanistically, immunoprecipitation assays demonstrated that TRIM65 binds to NACHT domain of NLRP3, promotes lys48- and lys63- linked ubiquitination of NLRP3 and restrains the NEK7-NLRP3 interaction, thereby inhibiting NLRP3 inflammasome assembly, caspase-1 activation, and IL-1β secretion. In vivo, three models of inflammatory diseases were used to confirm the suppression role of TRIM65 in NLRP3 inflammasome activation. TRIM65-deficient mice had a higher production of IL-1β induced by lipopolysaccharide in sera, and more IL-1β secretion and neutrophil migration in the ascites, and more severity of joint swelling and associated IL-1β production induced by monosodium urate, suggesting that TRIM65 deficiency was susceptible to inflammation. Therefore, the data elucidate a TRIM65-dependent negative regulation mechanism of NLRP3 inflammasome activation and provide potential therapeutic strategies for the treatment of NLRP3 inflammasome-related diseases.

scholarly journals Dimethyl Fumarate Alleviates NLRP3 Inflammasome Activation in Microglia and Sickness Behavior in LPS-Challenged Mice

2021 ◽  
Vol 12 ◽  
Author(s):  
Bora Tastan ◽  
Burak I. Arioz ◽  
Kemal Ugur Tufekci ◽  
Emre Tarakcioglu ◽  
Ceren Perihan Gonul ◽  
...  
Keyword(s):  
Cell Death ◽  
Nlrp3 Inflammasome ◽  
Forced Swim Test ◽  
Sickness Behavior ◽  
Dimethyl Fumarate ◽  
Inflammasome Activation ◽  
Caspase 1 ◽  
Nlrp3 Inflammasome Activation

NLRP3 inflammasome activation contributes to several pathogenic conditions, including lipopolysaccharide (LPS)-induced sickness behavior characterized by reduced mobility and depressive behaviors. Dimethyl fumarate (DMF) is an immunomodulatory and anti-oxidative molecule commonly used for the symptomatic treatment of multiple sclerosis and psoriasis. In this study, we investigated the potential use of DMF against microglial NLRP3 inflammasome activation both in vitro and in vivo. For in vitro studies, LPS- and ATP-stimulated N9 microglial cells were used to induce NLRP3 inflammasome activation. DMF’s effects on inflammasome markers, pyroptotic cell death, ROS formation, and Nrf2/NF-κB pathways were assessed. For in vivo studies, 12–14 weeks-old male BALB/c mice were treated with LPS, DMF + LPS and ML385 + DMF + LPS. Behavioral tests including open field, forced swim test, and tail suspension test were carried out to see changes in lipopolysaccharide-induced sickness behavior. Furthermore, NLRP3 and Caspase-1 expression in isolated microglia were determined by immunostaining. Here we demonstrated that DMF ameliorated LPS and ATP-induced NLRP3 inflammasome activation by reducing IL-1β, IL-18, caspase-1, and NLRP3 levels, reactive oxygen species formation and damage, and inhibiting pyroptotic cell death in N9 murine microglia via Nrf2/NF-κB pathways. DMF also improved LPS-induced sickness behavior in male mice and decreased caspase-1/NLRP3 levels via Nrf2 activation. Additionally, we showed that DMF pretreatment decreased miR-146a and miR-155 both in vivo and in vitro. Our results proved the effectiveness of DMF on the amelioration of microglial NLRP3 inflammasome activation. We anticipate that this study will provide the foundation consideration for further studies aiming to suppress NLRP3 inflammasome activation associated with in many diseases and a better understanding of its underlying mechanisms.

scholarly journals Defective endosome-TGN retrograde transport promotes NLRP3 inflammasome activation

2021 ◽  
Author(s):  
Romeo Ricci ◽  
Zhirong Zhang ◽  
Li Ran ◽  
Rossella Venditti ◽  
Zengzhen Liu ◽  
...  
Keyword(s):  
Nlrp3 Inflammasome ◽  
Inflammatory Responses ◽  
Retrograde Transport ◽  
Serum Levels ◽  
Inflammasome Activation ◽  
Dependent Manner ◽  
Potassium Efflux ◽  
Nlrp3 Inflammasome Activation ◽  
Broad Variety

Abstract Inflammasome complexes are pivotal in the innate immune response to pathogens and other danger signals. The NLRP3 inflammasome is activated in response to a broad variety of cellular stressors. Most of the stimuli act in a potassium efflux-dependent manner but a primary and converging sensing mechanism by the NLRP3 receptor initiating inflammasome assembly remains ill-defined. Here we show that NLRP3 activators disrupt endosome-TGN retrograde transport (ETRT) and lead to localization of NLRP3 to endosomal vesicles. Genetic and pharmacologic perturbation of ETRT leads to accumulation of phosphoinositol-4-phosphate (PI4P) in endosomes to which NLRP3 is recruited. Disruption of ETRT potentiates NLRP3 inflammasome activation in murine and human macrophages in vitro. Mice with defects in ETRT in the myeloid compartment are more susceptible to LPS-induced sepsis showing enhanced mortality and IL-1β serum levels as compared to control animals. Our study thus uncovers that changes in endocytic trafficking mediate NLRP3-dependent inflammatory responses.

scholarly journals Transcriptional Immune Signatures of Alveolar Macrophages and the Impact of the NLRP3 Inflammasome on Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) Replication

Viruses ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 1299
Author(s):  
Julie A. Hicks ◽  
Dongwan Yoo ◽  
Hsiao-Ching Liu
Keyword(s):  
Cell Culture ◽  
Alveolar Macrophages ◽  
Nlrp3 Inflammasome ◽  
Specific Inhibitor ◽  
Poly I:C ◽  
Inflammasome Activation ◽  
Polycytidylic Acid ◽  
Nlrp3 Inflammasome Activation ◽  
The Impact ◽  
Culture Supernatants

Porcine Reproductive and Respiratory Syndrome (PRRS) is a contagious viral (PRRSV) disease in pigs characterized by poor reproductive health, increased mortality, and reductions in growth rates. PRRSV is known to implement immuno-antagonistic mechanisms to evade detection and mute host responses to infection. To better understand the cellular immunosignature of PRRSV we have undertaken transcriptome and immunomodulatory studies in PRRSV-infected porcine alveolar macrophages (PAMs). We first used genome-wide transcriptome profiling (RNA-seq) to elucidate PRRSV-induced changes in the PAM transcriptome in response to infection. We found a number of cellular networks were altered by PRRSV infection, including many associated with innate immunity, such as, the NLRP3 inflammasome. To further explore the role(s) of innate immune networks in PRRSV-infected PAMs, we used an NLRP3-specific inhibitor, MCC950, to identify the potential functionality of the inflammasome during PRRSV replication. We found that PRRSV does quickly induce expression of inflammasome-associated genes in PAMs. Treatment of PAMs with MCC950 suggests NLRP3 inflammasome activation negatively impacts viral replication. Treatment of PAMs with cell culture supernatants from macrophages subjected to NLRP3 inflammasome activation (via polyinosinic-polycytidylic acid (poly I:C) transfection), prior to PRRSV infection resulted in significantly reduced viral RNA levels compared to PAMs treated with cell culture supernatants from macrophages subjected to NLRP3 inflammasome inhibition (MCC950 treatment/poly I:C transfection). This further supports a role for NLRP3 inflammasome activation in the innate macrophagic anti-PRRSV immune response and suggests that PRRSV is sensitive to the effects of NLRP3 inflammasome activity. Taken together, these transcriptome and immunoregulatory data highlight the complex changes PRRSV infection induces in the molecular immune networks of its cellular host.

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