Pro-inflammatory Mediator Genes Research Articles

Leptin Promotes the Expression of Pro-inflammatory Mediator Genes but Does Not Alter Osteoclastogenesis and Early Stage Differentiation of Osteoblasts.

Leptin, a hormone secreted by adipose tissue, plays a pivotal role in maintaining energy metabolism and bone quality. Dysregulation of leptin can lead to the development of various pathological conditions. For example, the concentration of leptin is increased in individuals with obesity, and this increased concentration is positively correlated with higher bone mass. In addition, mice lacking leptin or the leptin receptor exhibit substantial bone loss, further highlighting the pivotal role of leptin in regulating bone metabolism. However, the precise mechanism through which leptin affects bone remodeling remains unclear. The present study investigated the effect of leptin on osteoclastogenesis and osteoblastogenesis. Osteoblasts derived from MC3T3-E1 cells and osteoclasts derived from RAW 264.7 cells were used. The findings revealed that leptin did not substantially affect osteoclastogenesis or osteoblastogenesis. Furthermore, leptin did not affect cell viability during osteoclast differentiation. The expression of inflammatory mediators was increased in differentiating RAW 264.7 cells. However, the expression of critical bone resorptive genes, including Ctsk and tartrate-resistant acid phosphatase, was not elevated following leptin stimulation. By contrast, leptin did not alter the expression of key osteogenic genes in preosteoblasts in the early stage of differentiation. These data demonstrate that leptin can stimulate the expression of pro-inflammatory mediators in differentiating osteoclasts. These changes do not affect osteoblastogenesis or osteoclastogenesis. Leptin may downregulate bone resorption and enhance mineralization to increase bone mass.

Pro-Inflammatory Signaling Cascade Markers, Oxidative Stress-Inflammatory Signaling Axis, and Chronic Total Occlusion of Tibial Artery in Elderly Patients Suffering from Occlusion of Coronary Arteries.

Oxidative response is a risk factor in the progression of arterial atherosclerosis. This research study aimed to examine the effects of oxidative response on atherosclerotic susceptibility as well as the development of arteriosclerosis occlusions of the tibial artery through pro-inflammatory mediator genes in elderly patients with occlusion of coronary arteries. We determined that oxidative stress biomarkers (Malondialdehyde-modified Low-density Lipoprotein (MDA-LDL), Oxidized Low-density Lipoprotein (Ox-LDL) as well as Heme Oxygenase- 1 (HO-1)] and the expressions of pro-inflammatory mediator genes [Toll-like Receptor 4 (TLR4), Nuclear Factor kappa-B (NF-κB), Myeloid Differentiating factor 88 (MyD88) and Growth Arrest-specific gene 6 (GAS6)] have an impact on the severity of arteriosclerosis occlusions of tibial artery in elderly patients suffering from occlusion of coronary arteries. Levels of MDA-LDL, Ox-LDL, HO-1, TLR4, NF-κB, MyD88, and GAS6 were increased in the occlusion of tibial arteries + two-vessel coronary occlusion group compared to the CON group and occlusion of tibial arteries + one-vessel coronary occlusion group, respectively (p < 0.001); they were also elevated in occlusion of tibial arteries + multiple-vessel coronary occlusion group compared to occlusion of tibial arteries + one-vessel coronary occlusion group and occlusion of tibial arteries + two-vessel coronary occlusion group, respectively (P < 0.001). This has indicated the key roles of oxidative stress and pro-inflammatory mediator genes in arteriosclerosis occlusions of tibial artery in elderly patients with occlusion of coronary arteries. Oxidative response may promote the expressions of inflammatory genes and enhance susceptibility to arteriosclerosis occlusions of the tibial artery in elderly patients with chronic total coronary occlusions.

White-Nose Syndrome Disrupts the Splenic Lipidome of Little Brown Bats (Myotis lucifugus) at Early Disease Stages.

White-nose syndrome (WNS)-positive little brown bats (Myotis lucifugus) may exhibit immune responses including increased cytokine and pro-inflammatory mediator gene levels. Bioactive lipid mediators (oxylipins) formed by enzymatic oxidation of polyunsaturated fatty acids can contribute to these immune responses, but have not been investigated in WNS pathophysiology. Nonenzymatic conversion of polyunsaturated fatty acids can also occur due to reactive oxygen species, however, these enantiomeric isomers will lack the same signaling properties. In this study, we performed a series of targeted lipidomic approaches on laboratory Pseudogymnoascus destructans-inoculated bats to assess changes in their splenic lipidome, including the formation of lipid mediators at early stages of WNS. Hepatic lipids previously identified were also resolved to a higher structural detail. We compared WNS-susceptible M. lucifugus to a WNS-resistant species, the big brown bat (Eptesicus fuscus). Altered splenic lipid levels were only observed in M. lucifugus. Differences in splenic free fatty acids included both omega-3 and omega-6 compounds. Increased levels of an enantiomeric monohydroxy DHA mixture were found, suggesting nonenzymatic formation. Changes in previously identified hepatic lipids were confined to omega-3 constituents. Together, these results suggest that increased oxidative stress, but not an inflammatory response, is occurring in bats at early stages of WNS that precedes fat depletion. These data have been submitted to metabolomics workbench and assigned a study number ST002304.

Paraquat modulates immunological function in bone marrow-derived macrophages.

The herbicide paraquat (PQ) is known to affect the immune system. Many reports have indicated that PQ impacts on the viability and functions of the immune cells, however, the underlying mechanism in detail is still unknown. The aim of this study was to evaluate the effects of PQ on the free radical production, oxidative stress, cell death and pro-inflammatory gene expression of murine bone marrow-derived macrophages (BMDMs) from C57BL/6NJcl mice in vitro. BMDMs were incubated with PQ at 0, 200 and 400 µM concentrations for 24 h. Intracellular reactive oxygen species (ROS) production, apoptosis, cell viability, nitric oxide, inducible nitric oxide synthase (iNOS), and IL-6 expression levels were measured. The results revealed that PQ treatments led to a decrease in the cell viability and induced apoptotic cell death in a dose-dependent manner. Additionally, PQ also induced the generation of ROS. The mRNA level of the pro-inflammatory mediator genes iNOS and IL-6 were also elevated, while the level of lipid peroxide (malondialdehyde) production remained unaltered. Interestingly, the PQ treatment led to a decrease in the nitric oxide production. These results indicate that the increased cellular ROS production, due to the PQ treatment, induces apoptosis and the herbicide triggers production of iNOS and IL-6 in BMDMs.

Pro-Oxidative Stress, TLR4/NF-κB/MyD88 and GAS6 Pathways, and Atherosclerotic Susceptibility: Development of Tibial Artery Occlusions in Elderly Patients With Chronic Total Coronary Occlusions

Background: Oxidative stress is an important factor in the progression of arterial atherosclerosis. The present study investigated the effects of oxidative stress on atherosclerotic susceptibility and development of arteriosclerosis occlusions of tibial artery through pro-inflammatory mediator genes in elderly patients with chronic total coronary occlusions. Methods: We measured the oxidative stress biomarkers [malondialdehyde-modified low-density lipoprotein (MDA-LDL), oxidized low density lipoprotein (OX-LDL) and heme oxygenase-1 (HO-1)] and the expressions of pro-inflammatory mediator genes [toll-like receptor 4 (TLR4), nuclear factor kappa-B (NF-κB), myeloid differentiating factor 88 (MyD88) and growth arrest-specific gene 6 (GAS6)] for their impacts on the severity of arteriosclerosis occlusions of tibial artery in elderly patients with chronic total coronary occlusions. Findings: Levels of MDA-LDL, OX-LDL, HO-1, TLR4, NF-κB, MyD88 and GAS6 were significantly increased (P< 0.001) in the patients. This indicated the key roles for oxidative stress and pro-inflammatory mediator genes in arteriosclerosis occlusions of tibial artery in elderly patients with chronic total coronary occlusions. Interpretation: Oxidative stress may promote the over-expressions of pro-inflammatory genes and enhanced susceptibility to arteriosclerosis occlusions of tibial artery in elderly patients with chronic total coronary occlusions. Funding Information: Not applicable. Declaration of Interests: The authors declare that they have no competing financial interests. Ethics Approval Statement: The research was approved by the Human Research Ethics Committee of the Xuzhou Medical University and the Affiliated Huaian Hospital of Xuzhou Medical University according to the relevant laws and regulations of China, and the written informed consent was obtained from all the participants according to the Declaration of Helsinki.

Genetic Involvement in Dental Implant Failure: Association With Polymorphisms of Genes Modulating Inflammatory Responses and Bone Metabolism.

Implant loss is the most serious complication of dental implants. Although the problems and causes behind the implant failure are clearly defined today, determination of the underlying causes of failure varies by the case. The clusterization phenomenon of implant loss (multiple implant failures) implies the existence of genetic risk factors. Inflammation has a critical effect on osseointegration and implant success. Peri-implantitis is an inflammatory disease of tissue supporting the tooth or implant. Inflammation leads to loss of support tissue, particularly bone, resulting in failure of implants. A single nucleotide polymorphism (SNP) of pro-inflammatory mediator genes may affect their expression levels or amino acid sequence, and, consequently, the host inflammatory response. Since the end of the past century, many studies have been conducted to investigate the association of SNP with implant failure and related conditions. Involvement of several groups of genes-including interleukins, tumor necrosis factor-α, matrix metalloproteinases, and growth factors involved in immune regulation, inflammatory response, and bone metabolism-has been explored. Some have been found to be associated with implant loss and considered potential genetic risk factors for implant failure. In this review, we summarize results of recent studies of impact of genetic factors on dental implant failure.

Au Clusters Treat Rheumatoid Arthritis with Uniquely Reversing Cartilage/Bone Destruction.

Super‐small nanoclusters may intrinsically trigger specific molecular pathway for disease treatment in vitro/vivo. To prove the hypothesis the super‐small nanoclusters, e.g., Au clusters, are directly used to treat rheumatoid arthritis (RA) in vitro/vivo. RA is a chronic autoimmune disease that is characterized by the inflammation of joints and the unreversible destruction of the cartilage/bone. Au clusters significantly suppress lipopolysaccharide (LPS)‐induced proinflammatory mediator production in the murine macrophage cell line by inhibiting the signaling pathways that regulate the major proinflammatory mediator genes. In preclinical rat RA studies, Au clusters strongly prevent type II collagen‐induced rat RA without systemic side effects. Compared with the clinical first‐line anchored anti‐RA drug, methotrexate, Au clusters equally inhibit inflammation in vivo. Type II collagen‐induced rat RA is characterized with the destruction of cartilage/bone; treatment with Au clusters reverses the destruction of cartilage/bone to its normal state. This is because Au clusters directly inhibit receptor activator of nuclear factor‐κB ligand (RANKL)‐induced osteoclast differentiation and function through the downregulation of osteoclast‐specific genetic marker expression. However the methotrexate almost has no positive effect for this key issue in rat RA therapy. These data prove that the super‐small nanoclusters, e.g., Au clusters, could be a novel candidate nanodrug for RA treatment.

Genetic loci for alcohol-related life events and substance-induced affective symptoms: indexing the \u201cdark side\u201d of addiction

A limited number of genetic variants have been identified in traditional GWAS as risk or protective factors for alcohol use disorders (AUD) and related phenotypes. We herein report whole-genome association and rare-variant analyses on AUD traits in American Indians (AI) and European Americans (EA). We evaluated 742 AIs and 1711 EAs using low-coverage whole-genome sequencing. Phenotypes included: (1) a metric based on the occurrence of 36 alcohol-related life events that reflect AUD severity; (2) two alcohol-induced affective symptoms that accompany severe AUDs. We identified two new loci for alcohol-related life events with converging evidence from both cohorts: rare variants of K2P channel gene KCNK2, and rare missense and splice-site variants in pro-inflammatory mediator gene PDE4C. A NAF1-FSTL5 intergenic variant and an FSTL5 variant were respectively associated with alcohol-related life events in AI and EA. PRKG2 of serine/threonine protein kinase family, and rare variants in interleukin subunit gene EBI3 (IL-27B) were uniquely associated with alcohol-induced affective symptoms in AI. LncRNA LINC02347 on 12q24.32 was uniquely associated with alcohol-induced depression in EA. The top GWAS findings were primarily rare/low-frequency variants in AI, and common variants in EA. Adrenal gland was the most enriched in tissue-specific gene expression analysis for alcohol-related life events, and nucleus accumbens was the most enriched for alcohol-induced affective states in AI. Prefrontal cortex was the most enriched in EA for both traits. These studies suggest that whole-genome sequencing can identify novel, especially uncommon, variants associated with severe AUD phenotypes although the findings may be population specific.

Pro-inflammatory effects of palytoxin: an in vitro study on human keratinocytes and inflammatory cells.

Palytoxin (PLTX) is one of the most harmful marine toxins known so far. Although the ingestion of contaminated seafood is the most dangerous exposure route for humans, cutaneous and inhalational exposures are far more frequent, and can cause strong inflammatory reactions. However, little is known about the inflammatory events that follow the cutaneous exposure to the toxin. In this study, we investigated (1) the effects of both short (2 h) and long (24 h) term exposures of HaCaT keratinocytes to a sub-cytotoxic PLTX concentration on pro-inflammatory mediator gene expression and release and (2) the effect of PLTX-conditioned HaCaT cell media on undifferentiated (monocytes) and differentiated (macrophages; immature dendritic cells, iDCs; mature dendritic cells, mDCs) THP-1 cells. At 10-11 M, PLTX induced interleukin (IL)-6 and IL-8 release from HaCaT keratinocytes after 24 h of continuous exposure to the toxin, as well as after 23 h in toxin-free medium preceded by 1 h exposure to PLTX. Under the same experimental conditions, release of the inflammatory mediators prostaglandin-E2 and histamine was also found after both short and long exposures to the toxin. The conditioned media collected from HaCaT cells treated with PLTX increased the migration of the differentiated and undifferentiated THP-1 cells (potency rank order: monocytes ≥ iDCs > mDCs > macrophages) but did not induce cell differentiation. These results indicate that keratinocytes can be actively involved in the recruitment of inflammatory cells in response to cutaneous contact with PLTX. The lack of a significant effect on monocyte differentiation towards mature immune cells suggests that PLTX is endowed with irritant rather than sensitizing properties.

Attenuation of the macrophage inflammatory activity by TiO₂ nanotubes via inhibition of MAPK and NF-κB pathways.

Biomaterial implantation in a living tissue triggers the activation of macrophages in inflammatory events, promoting the transcription of pro-inflammatory mediator genes. The initiation of macrophage inflammatory processes is mainly regulated by signaling proteins of mitogen-activated protein kinase (MAPK) and by nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathways. We have previously shown that titania nanotubes modified Ti surfaces (Ti/TiO2) mitigate the immune response, compared with flat Ti surfaces; however, little is known regarding the underlying mechanism. Therefore, the aim of this study is to investigate the mechanism(s) by which this nanotopography attenuates the inflammatory activity of macrophages. Thus, we analyzed the effects of TiO2 nanotubes on the activation of MAPK and NF-κB signaling pathways in standard and lipopolysaccharide-evoked conditions. Results showed that the Ti/TiO2 significantly reduce the expression levels of the phosphorylated forms of p38, ERK1/2, c-Jun NH2-terminal kinase (JNK), IKKβ, and IkB-α. Furthermore, a significant reduction in the p65 nuclear accumulation on the nanotubular surface was remarked. Following, by using specific MAPK inhibitors, we observed that lipopolysaccharide-induced production of monocyte chemotactic protein-1 and nitric oxide was significantly inhibited on the Ti/TiO2 surface via p38 and ERK1/2, but not via JNK. However, the selective inhibitor for JNK signaling pathway (SP600125) was effective in reducing tumor necrosis factor alpha release as well as monocyte chemotactic protein-1 and nitric oxide production. Altogether, these data suggest that titania nanotubes can attenuate the macrophage inflammatory response via suppression of MAPK and NF-κB pathways providing a potential mechanism for their anti-inflammatory activity.

Necrostatin-1 Ameliorates Intracerebral Hemorrhage-Induced Brain Injury in Mice Through Inhibiting RIP1/RIP3 Pathway

Necroptosis is a recently discovered programmed necrosis, regulated by receptor interacting protein kinase 1 (RIP1) and RIP3 after death signal stimulation and could be specifically inhibited by necrostatin-1. The aim of this study was to investigate the role of RIP1 and RIP3 signal pathways in a mouse model of collagenase-induced intracerebral hemorrhage (ICH) and assess the effect of necrostatin-1 on brain injury after ICH. We found that RIP1 and RIP3 proteins were abundantly expressed and increased in mice brain after ICH. Necrostatin-1 pretreatment improved neurological function and attenuated brain edema in mice after ICH. Moreover, necrostatin-1 reduced RIP1-RIP3 interaction and propidium iodide (PI) positive cell death, and further inhibited microglia activation and pro-inflammatory mediator genes [tumor necrosis factor-a (TNF-α) and interleukin-1β (IL-1β)] expression after ICH. These findings indicate that RIP1/RIP3-mediated necroptosis is an important mechanism of cell death after ICH. Through inhibiting necroptosis, necrostatin-1 plays a protective role in reducing necrotic cell death after ICH. Necrostatin-1 is a promising therapeutic agent that protects cells from necroptosis and improves functional outcome.

Citral and eugenol modulate DNA damage and pro-inflammatory mediator genes in murine peritoneal macrophages.

Citral and eugenol have been broadly studied because of their anti-inflammatory, antioxidant and antiparasitic potentials. In this study, the effects of citral (25, 50 and 100µg/mL) and eugenol (0.31, 0.62, 1.24 and 2.48µg/mL) on the expression (RT-PCR) of the pro-inflammatory mediator genes NF-κB1, COX-2 and TNF-α were evaluated in mouse peritoneal macrophages with or without activation by a bacterial lipopolysaccharide (LPS). Additionally, the genotoxic potentials of two compounds and their capacities to modulate the DNA damage induced by doxorubicin (DXR) were investigated using the comet assay. The data revealed that neither citral nor eugenol changed COX-2, NF-κB1 or TNF-α expression in resting macrophages. However, in LPS-activated cells, citral induced the hypoexpression of COX-2 (100µg/mL) and TNF-α (50 and 100µg/mL). Hypoexpression of TNF-α was also detected after cellular exposure to eugenol at the highest concentration (2.48µg/mL). Both compounds exhibited genotoxic potential (citral at 50 and 100µg/mL and eugenol at all concentrations) but also showed chemopreventive effects, in various treatment protocols. Both citral and eugenol might modulate inflammatory processes and DXR-induced DNA damage, but the use of these compounds must be viewed with caution because they are also able to induce primary DNA lesions.

Protective effect of total alkaloids of Sophora alopecuroides on dextran sulfate sodium-induced chronic colitis

To investigate the effect of total alkaloids of Sophora alopecuroides (TASA) on dextran sulfate sodium (DSS)-induced colitis in mice. Chronic experimental colitis was induced by administration of 4 cycles of 4% DSS. Fifty mice were randomly distributed into 4 groups (normal, DSS, DSS/high-dose TASA, and DSS/low-dose TASA groups) by a random number table with body weight stratification. Mice in the normal group (n=11) and DSS-induced colitis control group (n=15) received control treatment of 20 mL/kg distilled water; DSS plus TASA high- and low-dose groups (n=12 each) were treated with TASA solution (20 mL/kg) at the doses of 60 mg/kg and 30 mg/kg, respectively. The severity of colitis was assessed on the basis of clinical signs, colon length, and histology scores. Moreover, secretory immunoglobulin A (sIgA) and haptoglobin (HP) were analyzed by enzyme linked immunosorbent assay; intercellular adhesion molecule 1 (ICAM-1) and macrophage-migration inhibitory factor (MIF) gene expressions were analyzed by quantitative reverse transcriptase realtime polymerase chain reaction (qRT-PCR) using SYBA green I; and nuclear factor κ B (NF-κ B) expression and activation and p65 interaction with the promoter of ICAM-1 gene were assessed by Western blotting and chromatin immunoprecipitation assay. TASA administration significantly attenuated the damage and substantially reduced HP elevation and maintained the level of cecum sIgA. TASA inhibited the ICAM-1 gene expression and had no effect on MIF gene expression. Also, TASA was able to reduce phospho-I κ B α (p-I κ B α) protein expression; however, it had no effect on the activation of I κ B kinase α (IKK α) and inhibitor of NF-κ B α (I κ B α). Moreover, TASA inhibited the p65 recruitment to the ICAM-1 gene promoter. TASA had a protective effect on DSS-induced colitis. Such effect may be associated with its inhibition of NF-κ B activation and blockade of NF-κ B-regulated transcription activation of proinflammatory mediator gene.

Erythropoietin Ameliorates Renal Ischemia and Reperfusion Injury via Inhibiting Tubulointerstitial Inflammation

Tubulointerstitial inflammation is the characteristics of renal ischemia reperfusion injury (IRI) that is inevitable in kidney transplantation. Erythropoietin (EPO) has recently been shown to have protective effects on renal IRI by anti-apoptosis and anti-oxidation. Here, the effect and mechanism of EPO on renal IRI were further investigated, with a focus on tubulointerstitial inflammation. Male Sprague-Dawley rats were administrated with saline or EPO prior to IRI induced by bilateral renal pedicle clamping. Twenty-four hours following reperfusion, the effects of EPO on renal IRI were assessed by renal function and structure, tubulointerstitial myeloperoxidase (MPO) positive neutrophils, and proinflammatory mediator gene expression. The translocation and activity of NF-κB in renal tissues were also evaluated. Compared with control groups, the EPO treated group exhibited lower serum urea and creatinine levels, limited tubular necrosis with a lower score of renal histological lesion. MPO positive cells in the tubulointerstitial area were greatly increased by IRI, but significantly reduced by the treatment of EPO. The gene expression of proinflammatory cytokines (IL-1β, IL-6, IL-10, and TNF-α) and chemokine (MCP-1) was also significantly decreased by EPO. In addition, less activation and nuclear-translocation of NF-κB was observed in the kidney treated by EPO as well. EPO improved renal function and structure in IRI rats via reducing neutrophils in the tubulointerstitium, the production of proinflammatory cytokines and chemokine, as well as the activation and nuclear-translocation of NF-κB. EPO may have potential clinical applications as an anti-inflammation agent clinically for a wide range of injury.

The Brain as a Target for Inflammatory Processes and Neuroprotective Strategies

The importance of glial cell-propagated inflammation (i.e., neuroinflammation) disorders such as Alzheimer's disease (AD) was viewed previously as a bystander effect, or epiphenomenon, with inflammation occurring when damaged neurons elicit an activation response by glia. However, an accumulating body of evidence has challenged this earlier perspective and indicates a more active role of neuroinflammation in the pathophysiology of progressive neurodegenerative disorders such as AD, Parkinson's disease, amyotrophic lateral sclerosis, and multiple sclerosis. This insight into pathophysiology evolved in concert with the appreciation that the brain is not as immunologically privileged as once thought. The central nervous system (CNS) has its own resident immune system, in which glial cells (microglia, astrocytes, and oligodendrocytes) not only serve supportive and nutritive roles for neurons but also engage from time to time in several "inflammatory" processes that defend the CNS from pathogens and help it to recover from stress and injury. These otherwise "normal" glial functions can sometimes result in a more severe and chronic neuroinflammatory cycle that actually promotes or propagates neurodegenerative disease. Excessive glial cell activation may thus constitute a viable target for the discovery of and development of neurodegenerative disease therapeutics. Suggestive clinical evidence in support of neuroinflammation as a drug discovery target for chronic neurodegenerative diseases, such as AD, comes from epidemiological and genetic linkage data. For example, long-term use of nonsteroidal anti-inflammatory drugs is correlated with a protective effect against AD, and certain polymorphisms in the genes for interleukin 1 and other proinflammatory mediator genes are associated with increased risk. In AD and Parkinson's disease, activated microglia and complement proteins have been identified in the brain regions most affected in these disorders. This report will briefly review selected clinical and preclinical data that reflect the prevailing approaches targeting neuroinflammation as a pathophysiological process contributing to the onset or progression of neurodegenerative diseases, as well as their neuroprotective potential.

??-ARRESTINS REGULATE LIPOPOLYSACCHARIDE (LPS)-INDUCED SIGNALING AND PROINFLAMMATORY GENE EXPRESSION

Previous studies have implicated a role of heterotrimeric Gi proteins in signaling leading to inflammatory mediator production induced by LPS. β-arrestins 1 and 2 alter G protein-coupled receptors signaling. We have reported that in the β-arrestins 2 knockout mouse embryonic fibroblasts, LPS-induced IL-6 production was decreased. We hypothesized that β-arrestins 1 and/or 2 regulate LPS-induced signaling and pro-inflammatory mediator gene expression. siRNA depletion of β-arrestins 1/2 in HEK 293 cells permanently transfected with TLR4, CD14 and MD2 and β-arrestin 2 knockout (KO) mice were employed to investigate the role of β-arrestins in LPS signaling. Our data demonstrate that siRNA induced β-arrestin 2 depletion decreased LPS-induced ERK1/2 activation (37±12%), whereas, β-arrestin 1 depletion had no effect. However, depletion of both β-arrestin 1 and 2 in HEK cells reduced LPS-induced IL-8 expression (46±2% and 39±4% respectively, Figure). LPS-induced TNFα and IL-6 production was significantly decreased (37±11%, 45±10%) in splenocytes from β-arrestin 2 KO mice compared to wild type mice. These data implicate a novel role of β-arrestins in regulating LPS-induced pro-inflammatory gene expression. (Supported by NIH GM27673 and GM67202)FigureData represent means ± SE from three independent experiments. *, p<0.05 compared to basal level; #, p<0.05 compared to LPS-stimulated groups.