CD14 is a glycosylphosphatidylinositol (GPI)-anchored receptor known to serve as a co-receptor for several Toll-like Receptors (TLRs) both at the cell surface and in the endosomal compartment. CD14 ...can be expressed by cells of both hematopoietic and non-hematopoietic origin as a cell membrane or secreted protein. Although CD14 was discovered more than 20 years ago, its activities remain largely to be defined. Most of the information available concerns CD14's role as a co-receptor working with TLR4 and facilitating cellular responses to low doses of lipopolysaccharide (LPS). Recent studies have highlighted and molecularly defined many other functions of this pattern recognition receptor (PRR). These functions include the mechanisms through which CD14 allows the activation of the TLR4-TRAM-TRIF pathway upon LPS stimulation; the capacity of CD14 to transduce a TLR4-independent signaling pathway leading to the activation of NFAT transcription factor family members with important consequences in myeloid cells; the CD14 influence on cell metabolism in conditions predisposing to obesity. In this review, we summarize recent progresses toward the molecular definition of the multiple roles exerted by CD14 in innate immune cells in response to LPS and the consequences of CD14 activation in physiologic and pathologic conditions.
Although bacterial endotoxin, such as lipopolysaccharide (LPS), plays a key role in the pathogenesis of nonalcoholic steatohepatitis (NASH), detailed mechanisms of this pathogenesis remain unclear. ...Here, we demonstrate that upregulation of CD14 by leptin-mediated signaling is critical to hyperreactivity against endotoxin during NASH progression. Upregulation of CD14 in Kupffer cells and hyperreactivity against low-dose LPS were observed in high-fat diet (HFD)-induced steatosis mice, but not chow-fed-control mice. Hyperresponsivity against low-dose LPS led to accelerated NASH progression, including liver inflammation and fibrosis. Administering leptin in chow-fed mice caused increased hepatic expression of CD14 via STAT3 signaling, resulting in hyperreactivity against low-dose LPS without steatosis. In contrast, a marked decrease in hepatic CD14 expression was observed in leptin-deficient ob/ob mice, despite severe steatosis. Our results indicate that obesity-induced leptin plays a crucial role in NASH progression via enhanced responsivity to endotoxin, and we propose a mechanism of bacteria-mediated progression of NASH.
Display omitted
► HFD-induced steatosis in mice promotes hyperresponsivity to low-dose LPS► CD14-positive Kupffer cells induced by feeding HFD regulate responsivity to LPS ► Leptin regulates CD14 expression in Kupffer cells via STAT3 signaling ► Leptin plays a critical role in NASH via control of responsivity to endotoxin
This study aimed to explore the impact of dietary Bacillus subtilis fmbj (BS) supplementation on acute intestinal dysfunction induced by lipopolysaccharide (LPS) in broilers. One hundred and eighty ...1-day-old male Arbor Acres broilers were randomly divided into three treatment groups, each comprising ten replicates of 6 birds. On d 20, LPS-challenged (LPS group and LPS-BS group) and LPS-unchallenged (CON group) broilers received intraperitoneal injections of 1 mg/kg body weight LPS solution and an equivalent volume of sterile saline, respectively. Compared to the CON group, LPS disrupted (P < 0.05) the morphology of the small intestine (jejunum or ileum), exacerbated (P < 0.05) serum, small intestinal, and small intestinal mitochondrial antioxidant capacity, induced (P < 0.05) small intestinal oxidative damage, and altered (P < 0.05) the expression of genes and proteins related to antioxidants, cell adhesion, and mitochondrial function in the jejunum. The LPS-BS group exhibited a tendency towards improvement in small intestinal morphology, serum, small intestinal, and small intestinal mitochondrial antioxidant capacity, small intestinal oxidative damage, and the expression of genes and proteins related to antioxidants, cell adhesion, and mitochondrial function in the jejunum when compared to the LPS group. In conclusion, BS supplementation may confer protection against LPS-induced acute intestinal dysfunction in broilers by enhancing the activation of SIRT1/PGC1α, suggesting its potential as a valuable additive for the poultry industry.
Intracortical microelectrodes afford researchers an effective tool to precisely monitor neural spiking activity. Additionally, intracortical microelectrodes have the ability to return function to ...individuals with paralysis as part of a brain computer interface. Unfortunately, the neural signals recorded by these electrodes degrade over time. Many strategies which target the biological and/or materials mediating failure modes of this decline of function are currently under investigation. The goal of this study is to identify a precise cellular target for future intervention to sustain chronic intracortical microelectrode performance. Previous work from our lab has indicated that the Cluster of Differentiation 14/Toll-like receptor pathway (CD14/TLR) is a viable target to improve chronic laminar, silicon intracortical microelectrode recordings. Here, we use a mouse bone marrow chimera model to selectively knockout CD14, an innate immune receptor, from either brain resident microglia or blood-derived macrophages, in order to understand the most effective targets for future therapeutic options. Using single-unit recordings we demonstrate that inhibiting CD14 from the blood-derived macrophages improves recording quality over the 16 week long study. We conclude that targeting CD14 in blood-derived cells should be part of the strategy to improve the performance of intracortical microelectrodes, and that the daunting task of delivering therapeutics across the blood-brain barrier may not be needed to increase intracortical microelectrode performance.
To test the utility of various biomarkers as indicators of gut dysfunction in cystic fibrosis (CF) and determine whether intraindividual variations in these measures are repeatable over short ...intervals and whether interindividual variations correlate with clinical outcomes.
We performed a cross-sectional, limited longitudinal study of children with CF aged 1-21 years who provided blood and stool samples at 2 or 3 visits, 2 weeks and 3 months apart, which were assayed for markers of intestinal inflammation (fecal calprotectin fCal, lipocalin-2 fLcn2, neopterin), and permeability (plasma lipopolysaccharide LPS antibodies, LPS-binding protein) by enzyme immunoassays. Control specimens were obtained from children without CF who had undergone esophagogastroduodenoscopy and had no evidence of gut inflammation.
Twenty-six of 29 participants with CF completed the study. Sixty-nine stools (57 case/12 control) and 76 plasmas (60 case/16 control) were analyzed. LPS antibody had reliable intraindividual stability. fCal, fLcn2, and neopterin were significantly greater in CF than in control samples. fCal was negatively correlated with 3-month interval change (Δ) in weight-for-age z-score, body mass index/weight-for-length z-score, and forced expiratory volume in 1 second. fLcn2 was negatively correlated with FEV1 but not with anthropometrics. No marker correlated with Δbody mass index/weight-for-length z-score or ΔFEV1.
fLcn2 is elevated in people with CF and might predict worse interval pulmonary function. Expanded studies are warranted to test if fLcn2 correlates with changes in additional outcomes.
A signal amplification electrochemical aptasensor for ultrasensitive detection of lipopolysaccharide (LPS) was fabricated. The sensor was constructed with a probe of LPS aptamer and a copper ...ions-mediated gold nanoparticles aggregate (Cu/Au NA) as a signal amplification material. The Cu/Au NAs comprising copper ions (Cu2+) and L-cysteine modified AuNPs were fabricated by a self-assembly process. For functionalization of the electrode, the carboxylic group of a mercaptoacetic acid self-assembly layer was covalently coupled with the amine group of the aptamer. The aptamer with high specificity and affinity can effectively gather the dissociative LPS firstly, and the Cu/Au NAs were captured by anionic groups of the carbohydrate portions from LPS molecules based on the specific interactions. With the employment of the sandwich-type biosensor, the strategy can significantly amplify the electrochemical signal for determination of trace amount of LPS. The sensing performance of the electrochemical sensor was investigated by differential pulse voltammetry (DPV) and the stripping peak currents of Cu re-oxidized to Cu2+ was used to monitor the level of LPS. The electrochemical aptasensor exhibited excellent sensitivity toward LPS with a detection limit of 0.033 pg/mL (S/N = 3). The biosensor also exhibited a high specificity toward LPS in the presence of other common interfering substances and was easily regenerated. Furthermore, the fabricated biosensor showed a good practical application for LPS determination in human serum samples.
•The fabricated LPS aptasensor was labeled with Cu/Au NAs for signal amplification.•The Cu/Au NAs were fabricated by copper ions and L-cysteine modified AuNPs.•The Cu/Au NAs not only simplified the analysis process, but also amplified the electrochemical signal.•The aptasensor was found to be greatly sensitive to LPS with a low detection limit.
Purpose: Lipopolysaccharides (LPS) have been found in abscesses in cases of apical periodontitis, and are believed to be a factor contributing to periapical disease becoming intractable. It has been ...reported that LPS break down in environments with a high pH. There are many materials on the market with different bases and additives that induce a high-pH environment, but the effects of these materials on LPS have not been clarified. The aim of the present study was to investigate changes in pH of various materials that induce a high-pH environment and to examine the effects on LPS concentration. Materials and methods: Five types of high pH-inducing materials were used in this experiment: CALVITAL (soft: CV-L group, hard: CV-P group), CALCIPEX PLANE Ⅱ (Cal group), Vitapex (Vit group), Bio-C Repair (Bio group), and ProRoot MTA (MTA group). Changes in the pH of the liquid culture medium were evaluated by measuring the pH of the supernatant at 1 h, 12 h, 1 day, and 3 days after addition of the high pH-inducing material. Changes in LPS concentration were measured using LPS originating from Escherichia coli. The concentration of LPS in the culture medium was set at 1,000 ng/mL, and the concentration of LPS remaining in the liquid culture medium 3 days after addition was measured by EndoLISA. Results: High pH values were found in the CV-L group, CV-P group, Cal group, and MTA group 1 h after the different high pH-inducing materials were immersed in the liquid culture medium. The CV-P group and the CV-L group showed significantly higher pH at 12 h following immersion, and the Cal group showed significantly lower values than the CV-L group and the Vit group at 1 day following immersion. On the 3rd day, the final measurement day, the Vit group showed significantly higher pH than all other groups except the CV-P group. The remaining concentration of LPS was high in the Cal group and low in the CV-P group, but there were no significant differences between any of the groups. Conclusion: The pH environment varied with the amount of free hydroxyl groups, depending on the composition of the material, and the concentration of LPS decreased with increasing pH. Calvital, a calcium hydroxide preparation kneaded to a somewhat firm consistency, indicated the possibility of reducing LPS.
Acute lung injury (ALI) remains a serious health issue with little improvement in our understanding of the pathophysiology and therapeutic approaches. We investigated the mechanism that ...lipopolysaccharide (LPS) induces early neutrophil recruitment to lungs and increases pulmonary vascular permeability during ALI. Intratracheal LPS induced release of pro-interleukin-1α (IL-1α) from necrotic alveolar macrophages (AM), which activated endothelial cells (EC) to induce vascular leakage via loss of vascular endothelial (VE)-cadherin. LPS triggered the AM purinergic receptor P2X7(R) to induce Ca2+ influx and ATP depletion, which led to necrosis. P2X7R deficiency significantly reduced necrotic death of AM and release of pro-IL-1α into the lung. CD14 was required for LPS binding to P2X7R, as CD14 neutralization significantly diminished LPS induced necrotic death of AM and pro-IL-1α release. These results demonstrate a key role for pro-IL-1α from necrotic alveolar macrophages in LPS-mediated ALI, as a critical initiator of increased vascular permeability and early neutrophil infiltration.
Display omitted
•Intratracheal LPS induces alveolar macrophage necrosis and pro-IL-1α release•Pro-IL-1α activates EC via IL-1/MyD88 signaling leading to loss of VE-cadherin•VE-cadherin loss facilitates neutrophil recruitment and vascular leakage•LPS induces AM necrosis via Ca2+ influx triggered by CD14/P2X7R signaling
The mechanisms for early initiation of LPS-induced acute lung injury are not well understood. Arditi and colleagues show that LPS initiates pulmonary inflammation by inducing necrosis in alveolar macrophages via a CD14-P2x7R-Ca2+ pathway. Necrosis leads to pro-IL-1α release and subsequent EC activation allowing neutrophil recruitment into the lungs.
Display omitted
•LPS and UCMS induced depressive-like states to different degrees.•LPS caused more evident behavioural changes and immune activation.•LPS and UCMS resulted in differential ...neurochemical changes in brain.•Hippocampus was relatively more vulnerable to LPS challenge.•UCMS caused more extensive decrease of 5-HT in the brain.
The immuno-inflammatory activation triggered by various stresses play an important role in pathophysiology of depression. The immune responses display differential pathological characters in different stresses. However, comparative data and analysis on behavioural, inflammatory and neurochemical changes in different stress-induced depression is limited. To imitate different stressful situations, in this study, mice were subjected to a single injection of LPS (0.5 mg/kg, i.p.) and UCMS (4 week period), respectively. LPS-stressed mice showed more immobility time in FST and TST, as well as more time in periphery in OFT than UCMS-stressed mice. Further, LPS-stressed mice showed robuster expression and release of TNF-α, IL-1β and IL-6 in serum and depression-related brain areas (prefrontal cortex, hippocampus and striatum) as compared to UCMS-stressed mice. The ELISA results showed that IDO expression was significantly increased following LPS and UCMS stresses, but more increased IDO expression was observed in prefrontal cortex and hippocampus of LPS-stressed mice. The decrease of 5-HT and BDNF was detected only in hippocampus of LPS-stressed mice, but in overall all the brain areas assessed in UCMS-stressed mice as compared to control. The data indicate that LPS induced more severe depressive-like behaviours and robuster immune activation than UCMS. Our study strongly imply that hippocampus is relatively more vulnerable to acute inflammatory challenge in depression, while chronic psychological stress is more likely to cause the multidimensional symptoms of clinical depression. Our findings provide more insight into pathophysiology in various stress-induced depression and also implicate a potential suitability of different stress models.
Aging-related, nonresolving inflammation in both the central nervous system (CNS) and periphery predisposes individuals to the development of neurodegenerative disorders (NDDs). Inflammasomes are ...thought to be especially relevant to immune homeostasis, and their dysregulation contributes to inflammation and NDDs. However, few agents have been clinically shown to reduce NDD incidence by targeting inflammasomes. Our study indicated that NLRP3 (NLR family, pyrin domain containing 3) inflammasome is involved in Parkinson disease (PD) progression in patients and various murine models. In addition, the small molecule kaempferol (Ka) protected mice against LPS- and SNCA-induced neurodegeneration by inhibiting NLRP3 inflammasome activation as evidenced by the fact that Ka reduced cleaved CASP1 expression and disrupted NLRP3-PYCARD-CASP1 complex assembly with concomitant decreased IL1B secretion. Mechanically, Ka promoted macroautophagy/autophagy in microglia, leading to reduced NLRP3 protein expression, which in turn deactivated the NLRP3 inflammasome. Intriguingly, ubiquitination was involved in Ka-induced autophagic NLRP3 degradation. These findings were further confirmed in vivo as knockdown of Atg5 expression or autophagy inhibitor treatment significantly inhibited the Ka-mediated NLRP3 inflammasome inhibition and neurodegeneration amelioration. Thus, we demonstrated that Ka promotes neuroinflammatory inhibition via the cooperation of ubiquitination and autophagy, suggesting that Ka is a promising therapeutic strategy for the treatment of NDDs.
Abbreviations: 3-MA: 3-methyladenine; AAV: adeno-associated virus; ACTB: actin, beta; AIF1/IBA1: allograft inflammatory factor 1; ATG5: autophagy related 5; ATG7: autophagy related 7; BafA1: bafilomycin A
1;
BECN1: beclin 1, autophagy related; CASP1: caspase 1; CNS: central nervous system; CQ: chloroquine; DA neurons: dopaminergic neurons; DAMPS: damage-associated molecular patterns; DAPI: 4',6-diamidino-2-phenylindole; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GFP: green fluorescent protein; GFAP: glial fibrillary acidic protein; IP: immunoprecipitation; i.p.: intraperitoneally; Ka: kaempferol; KD: knockdown; KO: knockout; LPS: lipopolysaccharide; IL1B: interleukin 1 beta; IL6: interleukin 6; Ly: lysate; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; MPTP: 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine; NC: negative control; NDD: neurodegenerative diseases; NLRP3: NLR family, pyrin domain containing 3; OE: overexpression; PD: Parkinson disease; poly-Ub: poly-ubiquitin; PTM: post-translational modification; PYCARD/ASC: PYD and CARD domain containing; Rapa: rapamycin; RFP: red fluorescent protein; SN: supernatant; SNCA: synuclein alpha; SNpc: substantia nigra pars compacta; SQSTM1: sequestosome 1; TH: tyrosine hydroxylase; TNF/TNF-alpha: tumor necrosis factor; Ub: ubiquitin; WT: wild type
PDF
