Exploring LPS-induced sepsis in rats and mice as a model to study potential protective effects of the nociceptin/orphanin FQ system

Effects of Omega-3 Polyunsaturated Fatty Acids on the Formation of Adipokines, Cytokines, and Oxylipins in Retroperitoneal Adi-Pose Tissue of Mice

Oxylipins and specialized pro-resolving lipid mediators (SPMs) derived from polyunsaturated fatty acids (PUFAs) are mediators that coordinate an active process of inflammation resolution. While these mediators have potential as circulating biomarkers for several disease states with inflammatory components, the source of plasma oxylipins/SPMs remains a matter of debate but may involve white adipose tissue (WAT). Here, we aimed to investigate to what extent high or low omega (n)-3 PUFA enrichment affects the production of cytokines and adipokines (RT-PCR), as well as oxylipins/SPMs (liquid chromatography-tandem mass spectrometry) in the WAT of mice during lipopolysaccharide (LPS)-induced systemic inflammation (intraperitoneal injection, 2.5 mg/kg, 24 h). For this purpose, n-3 PUFA genetically enriched mice (FAT-1), which endogenously synthesize n-3 PUFAs, were compared to wild-type mice (WT) and combined with n-3 PUFA-sufficient or deficient diets. LPS-induced systemic inflammation resulted in the decreased expression of most adipokines and interleukin-6 in WAT, whereas the n-3-sufficient diet increased them compared to the deficient diet. The n-6 PUFA arachidonic acid was decreased in WAT of FAT-1 mice, while n-3 derived PUFAs (eicosapentaenoic acid, docosahexaenoic acid) and their metabolites (oxylipins/SPMs) were increased in WAT by genetic and nutritional n-3 enrichment. Several oxylipins/SPMs were increased by LPS treatment in WAT compared to PBS-treated controls in genetically n-3 enriched FAT-1 mice. Overall, we show that WAT may significantly contribute to circulating oxylipin production. Moreover, n-3-sufficient or n-3-deficient diets alter adipokine production. The precise interplay between cytokines, adipokines, and oxylipins remains to be further investigated.

Antidepressant effect of PT-31, an α₂-adrenoceptor agonist, on lipopolysaccharide-induced depressive-like behavior in mice

Increasing evidence indicates that neuroinflammation, oxidative stress, and neurotrophic factors play a key role in the pathophysiology of major depressive disorder (MDD). In addition, the attenuation of inflammatory response has been considered a putative mechanism for MDD treatment. PT-31 is an imidazolidine derivative and a putative α₂-adrenoceptor agonist that has previously demonstrated antinociceptive activity. The present study aimed to investigate the effect of PT-31 on depressive-like behavior and lipopolysaccharide-induced neurochemical changes. To this end, mice received intraperitoneally saline or lipopolysaccharide (600 µg/kg), and 5 h postinjection animals were orally treated with saline, PT-31 (3, 10, and 30 mg/kg), or fluoxetine (30 mg/kg). Mice were subjected to the open field test (OFT) 6 and 24 h after lipopolysaccharide administration and to the tail suspension test (TST) 24 h postlipopolysaccharide. Subsequently, animals were euthanized, and brains were dissected for neurochemical analyses. The administration of lipopolysaccharide-induced sickness- and depressive-like behaviors, besides promoting an increase in myeloperoxidase activity and a reduction in brain-derived neurotrophic factor (BDNF) levels. Noteworthy, PT-31 3 mg/kg attenuated lipopolysaccharide-induced decreased locomotor activity 6 h after lipopolysaccharide in the OFT. All tested doses of PT-31 significantly reduced the immobility time of animals in the TST and attenuated lipopolysaccharide-induced increased myeloperoxidase activity in the cortex of mice. Our results demonstrate that PT-31 ameliorates behavioral changes promoted by lipopolysaccharide in OFT and TST, which is possibly mediated by attenuation of the inflammatory response.

Investigation of Antioxidant and Anti-inflammatory Properties of Berberine Nanomicelles: In vitro and In vivo Studies

INTRODUCTION

In the present study, neuroprotective effects of berberine (BBR) and berberine nanomicelle (BBR-NM) against lipopolysaccharides (LPS)-induced stress oxidative were investigated, and compared by evaluating their antioxidant and anti-inflammatory activities in PC12 cells, and rat brains. A fast, green, and simple synthesis method was used to prepare BBR-NMs.

METHOD

The prepared BBR-NMs were then characterized using dynamic light scattering (DLS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). In vitro experiments were carried out on the LPS-treated PC12 cell lines to investigate the anti-cytotoxic and antioxidant properties of BBR-NM and BBR. The results showed that BBR-NMs with a diameter of ~100 nm had higher protective effects against ROS production and cytotoxicity induced by LPS in PC12 cells in comparison with free BBR.

RESULTS

Moreover, in vivo experiments indicated that the activity levels of antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), increased in the brain of LPS-treated rats administrated with BBR-NM at the optimum dose of 100 mg.kg-1. BBR-NM administration also resulted in decreased concentration of lipid peroxidation (MDA) and pro-inflammatory cytokines, such as Serum interleukin-1 beta (IL-1β) and tumor necrosis factor-alpha (TNF-α).

CONCLUSION

Overall, BBR-NM demonstrated higher neuroprotective effects than free BBR, making it a promising treatment for improving many diseases caused by oxidative stress and inflammation.

Fast-track preparation of lung specimens for electron microscope observations of the pulmonary endothelial glycocalyx

The glycocalyx (GCX) covers the luminal surface of blood vessels and regulates vascular permeability. As GCX degradation predicts various types of vasculopathy, confirming the presence of this structure is useful for diagnosis. Since the GCX layer is very fragile, careful fixation is necessary to preserve its structure. We explored appropriate and feasible methodologies for visualizing the GCX layer using lung tissue specimens excised from anesthetized mice. Each specimen was degassed and immersed in Alcian blue (ALB) fixative solution, and then observed using electron microscopy. Specimens from septic mice were prepared as negative GCX controls. Using these immersion-fixed specimens, the GCX layer was successfully observed using both transmission and scanning electron microscopy; these observations were similar to those obtained using the conventional method of lanthanum perfusion fixation. Spherical aggregates of GCX were observed in the septic mouse specimens, and the GCX density was lower in the septic specimens than in the non-septic specimens. Of note, the presently reported methodology reduced the specimen preparation time from 6 to 2 days. We, therefore, concluded that our novel method could be applied to human lung specimens and could potentially contribute to the further elucidation of vasculopathies.

Currently Used Methods to Evaluate the Efficacy of Therapeutic Drugs and Kidney Safety

Kidney diseases with kidney failure or damage, such as chronic kidney disease (CKD) and acute kidney injury (AKI), are common clinical problems worldwide and have rapidly increased in prevalence, affecting millions of people in recent decades. A series of novel diagnostic or predictive biomarkers have been discovered over the past decade, enhancing the investigation of renal dysfunction in preclinical studies and clinical risk assessment for humans. Since multiple causes lead to renal failure, animal studies have been extensively used to identify specific disease biomarkers for understanding the potential targets and nephropathy events in therapeutic insights into disease progression. Mice are the most commonly used model to investigate the mechanism of human nephropathy, and the current alternative methods, including in vitro and in silico models, can offer quicker, cheaper, and more effective methods to avoid or reduce the unethical procedures of animal usage. This review provides modern approaches, including animal and nonanimal assays, that can be applied to study chronic nonclinical safety. These specific situations could be utilized in nonclinical or clinical drug development to provide information on kidney disease.

Specificity of Presepsin as a Biomarker of Bacterial Infection in Mouse Sepsis Models

INTRODUCTION

Since its discovery in 2002, presepsin (P-SEP) has been reported to be useful in the early diagnosis of sepsis and has been evaluated in many clinical studies. However, as antibodies that bind to mouse P-SEP were previously unavailable, serum P-SEP levels in mice are limited. This study used a P-SEP enzyme-linked immunosorbent assay kit to evaluate the changes in serum P-SEP levels in mouse sepsis models compared with changes in other inflammatory markers and determine whether P-SEP can function as a biomarker specific to bacterial infections.

METHODS

Sepsis was induced in mice via cecal ligation and puncture (CLP), induction with lipopolysaccharide (LPS), and cecal ligation (CL) model was created as a control for the CLP model, following which clinical biomarkers (P-SEP, C-reactive protein, and procalcitonin) were evaluated.

RESULTS

The 48-h survival rates in the CLP, CL, and LPS-induced sepsis models were 67%, 89%, and 57%, respectively. Serum C-reactive protein levels did not increase in the CLP and CL models within 24 h but significantly increased in the LPS-induced sepsis model. Serum procalcitonin levels increased in the CLP and CL models and especially increased in the LPS-induced sepsis model. In contrast, an increase in serum P-SEP level was found in the CLP model at 6 h compared with those at baseline, the CL, and LPS-induced sepsis models.

CONCLUSIONS

Mouse P-SEP is elevated early in infection and more specific to bacterial infection compared with other biomarkers.

Study of immunomodulatory effects of mesenchymal stem cell-derived exosomes in mouse model of LPS induced systemic inflammation

BACKGROUND

Sepsis is a debilitating systemic inflammation that resulted from infection or injury. Despite many advances in treatment, the resulting mortality rate has remained high due to increasing antibiotic resistance and aging communities. The present study investigated the effects of stem cell-derived exosomes in a mouse model of LPS-induced systemic inflammation.

MATERIALS AND METHODS

To induce sepsis, the LPS model was used. Mice were divided into three groups: normal, patient group (LPS + PBS), and treatment group (LPS + exosome). The treatment group received an intravenous exosome 1 h after induction of the model. Patient and treatment groups were sacrificed at 4, 6, 24, and 48 h after induction of the model, and their tissues were isolated. Blood samples were taken from animal hearts to perform biochemical and immunological tests. The study results were analyzed using Graph Pad Prism software version 9.

RESULTS

Mesenchymal stem cell-derived exosomes decreased serum levels of ALT and AST liver enzymes, decreased neutrophil to lymphocyte ratio (NLR), and improved kidney, liver, and lung tissue damage at 4, 6, and 24 h after model induction. At 24 h, the exosomes were able to reduce serum urea levels. This study revealed decreased levels of inflammatory cytokines such as IL-6, IL-1β, and TNF-α after exosome injection.

CONCLUSION

Our findings suggest that treating mice with stem cell-derived exosomes can ameliorate the destructive effects of inflammation caused by sepsis by reducing inflammatory factors and tissue damage.

Regulatory T Cells: Angels or Demons in the Pathophysiology of Sepsis?

Sepsis is a syndrome characterized by life-threatening organ dysfunction caused by the dysregulated host response to an infection. Sepsis, especially septic shock and multiple organ dysfunction is a medical emergency associated with high morbidity, high mortality, and prolonged after-effects. Over the past 20 years, regulatory T cells (Tregs) have been a key topic of focus in all stages of sepsis research. Tregs play a controversial role in sepsis based on their heterogeneous characteristics, complex organ/tissue-specific patterns in the host, the multi-dimensional heterogeneous syndrome of sepsis, the different types of pathogenic microbiology, and even different types of laboratory research models and clinical research methods. In the context of sepsis, Tregs may be considered both angels and demons. We propose that the symptoms and signs of sepsis can be attenuated by regulating Tregs. This review summarizes the controversial roles and Treg checkpoints in sepsis.

The Anti-Inflammatory and Antiapoptotic Effects of Nicorandil in Antisepsis Cardiomyopathy

Objective

To observe the effect of nicorandil on septic rats and explore the possible mechanism of its myocardial protection, so as to provide theoretical basis for the treatment of septic cardiomyopathy.

Methods

Sixty male clean SD rats were selected as the research objects and randomly divided into 3 groups by random number method: sham operation group (sham group), cecal ligation and perforation group (CLP group), nicorandil treatment group (nicorandil+CLP group). After the operation, the nicorandil group was pumped with nicorandil diluent 1 ml/h (2 mg/kg/h) with a micropump for 6 hours. The sham group and CLP group were pumped with the same amount of normal saline 1 ml/h for a total of 6 hours. After 24 hours, the survival of the rats in each group was observed. The expression of troponin I (cTnI), tumor necrosis factor α (TNF-α), and interleukin-1β (IL-1β) in the serum was detected. Then, the ventricle was harvested for the observation of the pathological changes of myocardium. Quantitative real-time polymerase chain reaction and immunostaining were used to detect myocardial tissue apoptosis, and Western blot methods were used to detect protein expression changes in nuclear factor-κB (NF-κB) pathways.

Results

24 hours after operation, the survival rate of the rats in the CLP group was 60%. There was a large amount of necrosis of myocardial cells and inflammatory cell infiltration. The survival rate of rats in the nicorandil+CLP group was 75%. Compared with the CLP group, the necrosis of myocardial cells was reduced, and there was still a small amount of inflammatory cell infiltration. In the CLP group, myocardial inflammation and apoptosis were significant, and NF-κB pathway was activated. On the contrary, the NF-κB pathway in the nicorandil+CLP group was inhibited, and the expression of inflammatory factors and apoptosis factors was inhibited.

Conclusion

Nicorandil can reduce the release of inflammatory factors in septic rats, improve the inflammatory response, reduce myocardial damage, and play a myocardial protective effect. Its mechanism may be related to the inhibition of the activation of NF-κB signaling pathway.

Immunotherapy-on-Chip Against an Experimental Sepsis Model

Lipopolysaccharide (LPS) is commonly used in murine sepsis models, which are largely associated with immunosuppression and collapse of the immune system. After adapting the LPS treatment to the needs of locally bred BALB/c mice, the present study explored the protective role of Micrococcus luteus peptidoglycan (PG)-pre-activated vaccine-on-chip technology in endotoxemia. The established protocol consisted of five daily intraperitoneal injections of 0.2 μg/g LPS, allowing longer survival, necessary for a therapeutic treatment application. A novel immunotherapy technology, the so-called vaccine-on-chip, consists of a 3-dimensional laser micro-textured silicon (Si) scaffold loaded with macrophages and activated in vitro with 1 μg/ml PG, which has been previously shown to exert a mild immunostimulatory activity upon subcutaneous implantation. The LPS treatment significantly decreased CD4 + and CD8 + cells, while increasing CD11b + , Gr1 + , CD25 + , Foxp3 + , and class II + cells. These results were accompanied by increased arginase-1 activity in spleen cell lysates and C-reactive protein (CRP), procalcitonin (PCT), IL-6, TNF-a, IL-10, and IL-18 in the serum, while acquiring severe sepsis phenotype as defined by the murine sepsis scoring. The in vivo application of PG pre-activated implant significantly increased the percentage of CD4 + and CD8 + cells, while decreasing the percentage of Gr1 + , CD25 + , CD11b + , Foxp3 + cells, and arginase-1 activity in the spleen of LPS-treated animals, as well as all serum markers tested, allowing survival and rescuing the severity of sepsis phenotype. In conclusion, these results reveal a novel immunotherapy technology based on PG pre-activated micro-texture Si scaffolds in LPS endotoxemia, supporting thus its potential use in the treatment of septic patients.

Analysis of N15-rat growth hormone after incubation with rat subcutaneous tissue and immune cells using ultra-pressure chromatography-mass spectrometry

Therapeutic proteins (TPs) are exposed to various immune cells like macrophages and neutrophils, especially after subcutaneous (SC) administration. It is well known that the immune cells can generate reactive oxygen species (ROS) and this may lead to oxidation of TPs. The oxidation can occur in the SC tissue after SC administration, during distribution to the immune organs like lymph nodes and spleen, and even in the blood circulation. The oxidation can lead to alteration of their pharmacokinetics and efficacy. Therefore, it is important to study the oxidation of TPs in the biological matrices using ultra-pressure chromatography-mass spectrometry. Rat growth hormone (rGH) was selected as a test protein due to its similarity with human growth hormone (hGH), which is widely used for treatment of growth hormone deficiency. In this manuscript, we have summarized sample processing strategy and ultra-pressure chromatography-mass spectrometry methodology to identify rGH and its degradation products after ex-vivo incubation with rat SC tissue, and in vitro incubation with rat splenocytes and canine peripheral blood mononuclear cells (cPBMCs) as a model foreign host species. We did not observe oxidation of rGH in these biological matrices. This could be due to very minor yields of oxidation products, lack of sensitivity of the mass spectrometry method, loss of protein during sample processing, rapid turnover of oxidized protein or a combination of all factors.

Formaldehyde reinforces pro-inflammatory responses of macrophages through induction of glycolysis

Formaldehyde (FA) is widely used in chemical industry, which is also known as a common indoor air pollutant. Exposure of FA has been associated with multiple detrimental health effects. Our previous study showed that FA could inhibit the development of T lymphocytes in mice, leading to impaired immune functions. Macrophages are important innate immune cells which trigger inflammatory responses in tissues. In the present study, FA exposure at 2.0 mg/m³ was found to enhance the pro-inflammatory responses of macrophages in male BALB/c mice, which was confirmed by elevated pro-inflammatory cytokine release and NO secretion in macrophages isolated from the FA-exposed mice and in vitro macrophage models upon lipopolysaccharide stimulation. Glycolysis is the key metabolic process for the classical activation of macrophages, which was found to be elevated in the in vitro macrophage models treated with FA at 50 and 100 μM concentrations for 18 h. HIF-1α and the associated proteins in its signaling cascade, which are known to mediate glycolytic metabolism and inflammatory responses, were found to be upregulated by 50 and 100 μM FA in THP-1 derived and RAW264.7 macrophage models, and the enhanced pro-inflammatory responses induced by 100 μM FA were reversed by inhibitory compounds interfering with glucose metabolism or suppressing HIF-1α activity. Collectively, the results in this study revealed that FA could enhance the pro-inflammatory responses of macrophages through the induction of glycolysis, which outlined the FA-triggered metabolic and functional alterations in immune cells.

Pubertal immune challenge suppresses the hypothalamic-pituitary-gonadal axis in male and female mice

Kisspeptin is a neuropeptide responsible for propagating the hypothalamic-pituitary-gonadal (HPG) axis and initiating puberty. Pubertal exposure to an immune challenge causes enduring sexual behavior dysfunction in males and females, but the mechanism underlying this stress-induced sexual dysfunction remains unknown. Previous findings show that stress exposure can downregulate the HPG axis in adult females. However, it is unclear whether stress induced HPG axis suppression is limited to adult females or also extends to males and to pubertal animal models. The current study was designed to investigate the sex-specific consequences of a pubertal immune challenge on specific components of the HPG axis. Six-week old pubertal male and female mice were treated with saline or with lipopolysaccharide, a bacterial endotoxin. Expression of hypothalamic Kiss1 and Kiss1R as well as serum concentrations of luteinizing hormone, follicle-stimulating hormone, and growth hormone were examined. Pubertal lipopolysaccharide treatment decreased hypothalamic Kiss1, but not Kiss1R, expression in both males and females. Furthermore, only males showed decreases in circulating luteinizing and follicle-stimulating hormones. These results show that pubertal immune challenge suppresses the HPG axis by inhibiting Kiss1 production and decreasing serum gonadotropin concentrations in pubertal males, but points to a different mechanism in pubertal females.

GFI-1 Protects Against Lipopolysaccharide-Induced Inflammatory Responses and Apoptosis by Inhibition of the NF-κB/TNF-α Pathway in H9c2 Cells

Growth factor independence 1 (Gfi-1) has been widely studied for its anti-inflammatory and anti-apoptotic effects. However, whether Gfi-1 has similar effects on H9c2 cardiomyocytes has not yet been reported. In this study, we explored the effect of Gfi-1 on lipopolysaccharide (LPS)-induced inflammatory responses and apoptosis in H9c2 cells. We found that LPS induced the increased expression of TNF-α and IL-6 in the LPS group. After transfection of the Gfi-1 overexpression plasmid, the expression of TNF-α and IL-6 decreased significantly in the LPS + Gfi-1 group. Gfi-1 clearly blocked LPS-induced NF-κB, TNF-α, TNFR1, cleaved-caspase-3 and cleaved-caspase-8 expression and increased Gfi-1 and Bcl-xL expression in H9c2 cells. Similarly, compared with the LPS group, Gfi-1 significantly decreased the expression of cleaved-caspase3/8 and increased the expression of Bcl-xL in the LPS + Gfi-1 group, as verified by immunocytochemical analysis. Furthermore, Gfi-1 markedly inhibited LPS-induced H9c2 cardiomyocyte apoptosis in the LPS + Gfi-1 group, as determined by TEM, TUNEL and flow cytometry. Taken together, these results demonstrate that Gfi-1 may have protective effects against LPS-induced inflammatory responses and apoptosis in H9c2 cells. Gfi-1 may be a novel molecule for treating septic cardiomyopathy.

A novel isoquinoline derivative exhibits anti-inflammatory properties and improves the outcomes of endotoxemia

BACKGROUND

Sepsis initiates an inflammatory response that causes widespread injury, and candidates for related myocardial depressant factors include cytokines and nitric oxide (NO). Nuclear factor kappa-B (NF-κB) stimulated by toll-like receptor 4 activation in sepsis mediates the transcription of multiple proinflammatory genes. These inflammatory mediators can cause myocardial dysfunction, which may deteriorate sepsis outcomes. To address this risk, we investigated the potential beneficial effects of a novel isoquinolines derivative, CYY054c, in LPS-induced inflammatory response leading to endotoxemia.

METHODS

The effects of CYY054c on cytokine and inflammatory-related protein production were evaluated in lipopolysaccharide (LPS)-stimulated macrophages. To determine whether CYY054c alleviates inflammatory storm-induced myocardial dysfunction in vivo, LPS was injected in rats, and cardiac function was measured by a pressure-volume loop.

RESULTS

CYY054c inhibited LPS-induced NF-κB expression in macrophages and reduced the release of tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6), as well as the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). In the animal studies, CYY054c alleviated LPS-upregulated plasma TNF-α, IL-1β, IL-6, and NO concentrations, as well as cardiac monocyte chemotactic protein-1, iNOS, and COX-2 expression in rats, contributing to the improvement of cardiac function during endotoxemia.

CONCLUSIONS

The reduction of NF-κB-mediated inflammatory mediators and the maintenance of hemodynamic performance by CYY054c improved the outcomes during endotoxemia. CYY054c may be a potential therapeutic agent for sepsis.

Female- and Intruder-induced Ultrasonic Vocalizations in C57BL/6J Mice as Proxy Indicators for Animal Wellbeing

Female urine-induced male mice ultrasonic vocalizations (FiUSV) are ultrasonic vocalizations produced by adult male mice after presentation of adult female urine, whereas intruder-induced ultrasonic vocalizations (IiUSV) are produced by resident adult female mice when interacting with an intruder female mouse. These affiliative behaviors may be reduced when mice have decreased wellbeing or are in pain and distress. To determine whether FiUSV and IiUSV can be used as proxy indicators of animal wellbeing, we assessed FiUSV produced by male C57BL/6J mice in response to female urine and IiUSV produced by female C57BL/6J mice in response to a female intruder at baseline and 1 and 3 h after administration of a sublethal dose of LPS (6 or 12.5 mg/kg IP) or an equal volume of saline. Behavior was assessed by evaluating orbital tightness, posture, and piloerection immediately after USV collection. We hypothesized that LPS-injected mice would have a decreased inclination to mate or to interact with same-sex conspecifics and therefore would produce fewer USV. At baseline, 32 of 33 male mice produced FiUSV (149 ± 127 USV in 2 min), whereas all 36 female mice produced IiUSV (370 ± 156 USV in 2 min). Saline-injected mice showed no change from baseline at the 1- and 3-h time points, whereas LPS-injected mice demonstrated significantly fewer USV than baseline, producing no USV at both 1 and 3 h. According to orbital tightness, posture, and piloerection, LPS-injected mice showed signs of poor wellbeing at 3 h but not 1 h. These findings indicate that FiUSV and IiUSV can be used as proxy indicators of animal wellbeing associated with acute inflammation in mice and can be detected before the onset of clinical signs.

An Effective Method for Acute Vagus Nerve Stimulation in Experimental Inflammation

Neural reflexes regulate inflammation and electrical activation of the vagus nerve reduces inflammation in models of inflammatory disease. These discoveries have generated an increasing interest in targeted neurostimulation as treatment for chronic inflammatory diseases. Data from the first clinical trials that use vagus nerve stimulation (VNS) in treatment of rheumatoid arthritis and Crohn’s disease suggest that there is a therapeutic potential of electrical VNS in diseases characterized by excessive inflammation. Accordingly, there is an interest to further explore the molecular mechanisms and therapeutic potential of electrical VNS in a range of experimental settings and available genetic mouse models of disease. Here, we describe a method for electrical VNS in experimental inflammation in mice.

Ex vivo modelling of the formation of inflammatory platelet-leucocyte aggregates and their adhesion on endothelial cells, an early event in sepsis

Septicaemia is an acute inflammatory reaction in the bloodstream to the presence of pathogen-associated molecular patterns. Whole blood stimulation assays capture endotoxin-induced formation of aggregates between platelets and leucocytes using flow cytometry. We wanted to assess extent of spontaneous aggregate formation in whole blood stimulation assays and compare the effects of endotoxin and heat-killed, clinically relevant, bacterial pathogens on aggregate formation and then on adhesion of aggregates to TNFα-stimulated endothelial cells. We found that endotoxin (from Escherichia coli or Salmonella enteritidis) was not a suitable stimulus to provoke platelet-leucocyte aggregates in vitro, as it did not further increase the extent of aggregates formed spontaneously in stasis of hirudin-anticoagulated blood. Specifically, whole blood samples stimulated with or without LPS produced aggregates with a mean surface area of 140.97 and 117.68 μm2, respectively. By contrast, incubation of whole blood with heat-killed Klebsiella pneumoniae or Staphylococcus aureus produced significantly enhanced and complex cellular aggregates (with a mean surface area of 470.61 and 518.39 μm2, respectively) which adhered more frequently to TNFα (and free fatty acid)-stimulated endothelial cells. These were reliably captured by scanning electron microscopy. Adhesion of cellular aggregates could be blocked by incubation of endothelial cells with a commercial P-selectin antibody and an angiopoietin-2 ligand trap. In conclusion, we have developed an in vitro method that models the acute inflammatory reaction in whole blood in the presence of sepsis-relevant bacterial pathogen surfaces.

Peripheral-Central Neuroimmune Crosstalk in Parkinson's Disease: What Do Patients and Animal Models Tell Us?

The brain is no longer considered an immune privileged organ and neuroinflammation has long been associated with Parkinson's disease. Accumulating evidence demonstrates that innate and adaptive responses take place in the CNS. The extent to which peripheral immune alterations impacts on the CNS, or vice and versa, is, however, still a matter of debate. Gaining a better knowledge of the molecular and cellular immune dysfunctions present in these two compartments and clarifying their mutual interactions is a fundamental step in understanding and preventing Parkinson's disease (PD) pathogenesis. This review provides an overview of the current knowledge on inflammatory processes evidenced both in PD patients and in toxin-induced animal models of the disease. It discusses differences and similarities between human and animal studies in the context of neuroinflammation and immune responses and how they have guided therapeutic strategies to slow down disease progression. Future longitudinal studies are necessary and can help gain a better understanding on peripheral-central nervous system crosstalk to improve therapeutic strategies for PD.

Fasciola hepatica GST downregulates NF-κB pathway effectors and inflammatory cytokines while promoting survival in a mouse septic shock model

Parasitic helminths and helminth-derived molecules have demonstrated to possess powerful anti-inflammatory properties and confirmed therapeutic effects on inflammatory diseases. The helminth Fasciola hepatica has been reported to suppress specific Th1 specific immune responses induced by concurrent bacterial infections, thus demonstrating its anti-inflammatory ability in vivo. In this study, we demonstrate that native F. hepatica glutathione S-transferase (nFhGST), a major parasite excretory-secretory antigen, majorly comprised of Mu-class GST isoforms, significantly suppresses the LPS-induced TNFα and IL1β of mouse bone-marrow derived macrophages in vitro and the pro-inflammatory cytokine/chemokine storm within C57BL/6 mice exposed to lethal doses of LPS increasing their survival rate by more than 85%. Using THP1-Blue CD14 cells, a human monocyte cell line, we also demonstrate that nFhGST suppresses NF-κB activation in response to multiple TLR-ligands, including whole bacteria clinical isolates and this suppression was found to be dose-dependent and independent of the timing of exposure. Moreover, the suppressive effect of nFhGST on NF-κB activation was shown to be independent of enzyme activity or secondary structure of protein. As part of its anti-inflammatory effect nFhGST target multiple proteins of the canonic and non-canonic NF-κB signaling pathway as well as also JAK/STAT pathway. Overall, our results demonstrate the potent anti-inflammatory properties of nFhGST and its therapeutic potential as an anti-inflammatory agent.

Fh15 Blocks the Lipopolysaccharide-Induced Cytokine Storm While Modulating Peritoneal Macrophage Migration and CD38 Expression within Spleen Macrophages in a Mouse Model of Septic Shock

Sepsis caused by Gram-negative bacteria is the consequence of an unrestrained infection that continuously releases lipopolysaccharide (LPS) into the bloodstream, which triggers an uncontrolled systemic inflammatory response leading to multiorgan failure and death. After scrutinizing the immune modulation exerted by a recombinant Fasciola hepatica fatty acid binding protein termed Fh15, our group demonstrated that addition of Fh15 to murine macrophages 1 h prior to LPS stimulation significantly suppresses the expression of proinflammatory cytokines tumor necrosis factor alpha (TNF-α) and interleukin-1β (IL1-β). The present study aimed to demonstrate that Fh15 could exert a similar anti-inflammatory effect in vivo using a mouse model of septic shock. Among the novel findings reported in this article, (i) Fh15 suppressed numerous serum proinflammatory cytokines/chemokines when injected intraperitoneally 1 h after exposure of animals to lethal doses of LPS, (ii) concurrently, Fh15 increased the population of large peritoneal macrophages (LPMs) in the peritoneal cavity (PerC) of LPS-injected animals, and (iii) Fh15 downregulated the expression on spleen macrophages of CD38, a cell surface ectoenzyme with a critical role during inflammation. These findings present the first evidence that the recombinant parasitic antigen Fh15 is an excellent modulator of the PerC cell content and in vivo macrophage activation, endorsing Fh15's potential as a drug candidate against sepsis-related inflammatory response.IMPORTANCE Sepsis is a potentially life-threatening complication of an infection. Sepsis is mostly the consequence of systemic bacterial infections leading to exacerbated activation of immune cells by bacterial products, resulting in enhanced release of inflammatory mediators. Lipopolysaccharide (LPS), the major component of the outer membrane of Gram-negative bacteria, is a critical factor in the pathogenesis of sepsis, which is sensed by Toll-like receptor 4 (TLR4). The scientific community highly pursues the development of antagonists capable of blocking the cytokine storm by blocking TLR4. We report here that a recombinant molecule of 14.5 kDa belonging to the Fasciola hepatica fatty acid binding protein (Fh15) is capable of significantly suppressing the LPS-induced cytokine storm in a mouse model of septic shock when administered by the intraperitoneal route 1 h after a lethal LPS injection. These results suggest that Fh15 is an excellent candidate for drug development against endotoxemia.

RhoA/ROCK-2 Pathway Inhibition and Tight Junction Protein Upregulation by Catalpol Suppresses Lipopolysaccaride-Induced Disruption of Blood-Brain Barrier Permeability

Lipopolysaccaride (LPS) directly or indirectly injures brain microvascular endothelial cells (BMECs) and damages the intercellular tight junction that gives rise to altered blood-brain barrier (BBB) permeability. Catalpol plays a protective role in LPS-induced injury, but whether catalpol protects against LPS-caused damage of BBB permeability and the underlying mechanism remain to be delineated. Prophylactic protection with catalpol (5 mg/kg, i.v.) consecutively for three days reversed the LPS-induced damage of BBB by decreased Evans Blue (EB) leakage and restored tight junctions in C57 mice. Besides, catalpol co-administrated with LPS increased BMECs survival, decreased their endothelin-1, TNF-Α and IL-6 secretion, improved transmembrane electrical resistance in a time-dependent manner, and in addition increased the fluorescein sodium permeability coefficient of BMECs. Also, transmission electron microscopy showed catalpol protective effects on tight junctions. Fluorescence staining displayed that catalpol reversed the rearrangement of the cytoskeleton protein F-actin and upregulated the tight junction protein of claudin-5 and ZO-1, which have been further demonstrated by the mRNA and protein expression levels of ZO-1, ZO-2, ZO-3, claudin-5, and occludin. Moreover, catalpol concurrently downregulated the mRNA and protein levels of RhoA, and ROCK2, the critical proteins in the RhoA/ROCK2 signaling pathway. This study thus indicated that catalpol, via inhibition of the RhoA/ROCK2 signaling pathway, reverses the disaggregation of cytoskeleton actin in BMECs and prevents down-regulation of junctional proteins, such as claudin-5, occludin, and ZO-1, and decreases endothelin-1 and inflammatory cytokine secretion, eventually alleviating the increase in LPS-induced BBB permeability.

Recovery from an acute systemic and central LPS-inflammation challenge is affected by mouse sex and genetic background

Genetic and sexual factors influence the prevalence and the pathogenesis of many inflammatory disorders. In this study their relevance on the peripheral and central inflammatory status induced by a peripheral injection of lipopolysaccharide (LPS) was evaluated. BALB/c and CD-1 male and female mice were intraperitoneally injected with LPS. Spleens and brains were collected 2 and 72 hours later to study the levels of IL-6, TNF-α and IL-1β. Percentage of microglia and astrocytes was determined in the cortex and hippocampus. Locomotor activity was registered before and during the 72 hours after LPS-treatment. Two hours after LPS-injection, a peripheral increase of the three cytokines was found. In brains, LPS increased TNF-α only in males with higher levels in CD-1 than BALB/c. IL-1β increased only in CD-1 males. IL-6 increased in both strains with lower levels in BALB/c females. Peripheral and central levels of cytokines decline 72 hrs after LPS-treatment whilst a significantly increase of Iba-1 expression was detected. A dramatic drop of the locomotor activity was observed immediately after LPS injection. Our results show that acute systemic administration of LPS leads to peripheral and central increase of pro-inflammatory cytokines and microglia activation, in a strain and sex dependent manner.

An MD2-derived peptide promotes LPS aggregation, facilitates its internalization in THP-1 cells, and inhibits LPS-induced pro-inflammatory responses

MD2, a 160-residue accessory glycoprotein, is responsible for the recognition and binding of Gram-negative bacterial membrane component, lipopolysaccharide (LPS). Internalization of pathogen inside the mononuclear phagocytes has also been attributed to MD2 which leads to the clearance of pathogens from the host. However, not much is known about the segments in MD2 that are responsible for LPS interaction or internalization of pathogen inside the defense cells. A 16-residue stretch (MD54) from MD2 protein has been identified that possesses a short heptad repeat sequence and four cationic residues enabling it to participate in both hydrophobic and electrostatic interactions with LPS. An MD54 analog of the same size was also designed in which a leucine residue at a heptadic position was replaced with an alanine residue. MD54 but not its analog, MMD54 induced aggregation of LPS and aided in its internalization within THP-1 monocytes. Furthermore, MD54 inhibited LPS-induced nuclear translocation of NF-κB in PMA-treated THP-1 and TLR4/MD2/CD14-transfected HEK-293T cells and the production of pro-inflammatory cytokines. In addition, in in vivo experiments, MD54 showed marked protection and survival of mice against LPS-induced inflammation and death. Overall, we have identified a short peptide with heptad repeat sequence from MD2 that can cause aggregation of LPS and abet in its internalization within THP-1 cells, resulting in attenuation of LPS-induced pro-inflammatory responses in vitro and in vivo.

Acute Neuroinflammatory Response in the Substantia Nigra Pars Compacta of Rats after a Local Injection of Lipopolysaccharide

Models of Parkinson's disease with neurotoxins have shown that microglial activation does not evoke a typical inflammatory response in the substantia nigra, questioning whether neuroinflammation leads to neurodegeneration. To address this issue, the archetypal inflammatory stimulus, lipopolysaccharide (LPS), was injected into the rat substantia nigra. LPS induced fever, sickness behavior, and microglial activation (OX42 immunoreactivity), followed by astrocyte activation and leukocyte infiltration (GFAP and CD45 immunoreactivities). During the acute phase of neuroinflammation, pro- and anti-inflammatory cytokines (TNF-α, IL-1β, IL-6, IL-4, and IL-10) responded differentially at mRNA and protein level. Increased NO production and lipid peroxidation occurred at 168 h after LPS injection. At this time, evidence of neurodegeneration could be seen, entailing decreased tyrosine hydroxylase (TH) immunoreactivity, irregular body contour, and prolongation discontinuity of TH⁺ cells, as well as apparent phagocytosis of TH⁺ cells by OX42⁺ cells. Altogether, these results show that LPS evokes a typical inflammatory response in the substantia nigra that is followed by dopaminergic neurodegeneration.

Conserved gene regulation during acute inflammation between zebrafish and mammals

Zebrafish (Danio rerio), largely used as a model for studying developmental processes, has also emerged as a valuable system for modelling human inflammatory diseases. However, in a context where even mice have been questioned as a valid model for these analysis, a systematic study evaluating the reproducibility of human and mammalian inflammatory diseases in zebrafish is still lacking. In this report, we characterize the transcriptomic regulation to lipopolysaccharide in adult zebrafish kidney, liver, and muscle tissues using microarrays and demonstrate how the zebrafish genomic responses can effectively reproduce the mammalian inflammatory process induced by acute endotoxin stress. We provide evidence that immune signaling pathways and single gene expression is well conserved throughout evolution and that the zebrafish and mammal acute genomic responses after lipopolysaccharide stimulation are highly correlated despite the differential susceptibility between species to that compound. Therefore, we formally confirm that zebrafish inflammatory models are suited to study the basic mechanisms of inflammation in human inflammatory diseases, with great translational impact potential.

A state of delirium: Deciphering the effect of inflammation on tau pathology in Alzheimer's disease

Alzheimer's disease (AD), the predominant form of dementia, is highly correlated with the abnormal hyperphosphorylation and aggregation of tau. Immune responses are key drivers of AD and how they contribute to tau pathology in human disease remains largely unknown. This review summarises current knowledge on the association between inflammatory processes and tau pathology. While, preclinical evidence suggests that inflammation can indeed induce tau hyperphosphorylation at both pre- and post-tangles epitopes, a better understanding of whether this develops into advanced pathological features such as neurofibrillary tangles is needed. Microglial cells, the immune phagocytes in the central nervous system, appear to play a key role in regulating tau pathology, but the underlying mechanisms are not fully understood. Their activation can be detrimental via the secretion of pro-inflammatory mediators, particularly interleukin-1β, but also potentially beneficial through phagocytosis of extracellular toxic tau oligomers. Nevertheless, anti-inflammatory treatments in animal models were found protective, but whether or not they affect microglial phagocytosis of tau species is unknown. However, one major challenge to our understanding of the role of inflammation in the progression of tau pathology is the preclinical models used to address this question. They mostly rely on the use of septic doses of lipopolysaccharide that do not reflect the inflammatory conditions experienced AD patients, questioning whether the impact of inflammation on tau pathology in these models is dose-dependent and relevant to the human disease. The use of more translational models of inflammation corroborated with verification in clinical investigations are necessary to progress our understanding of the interplay between inflammation and tau pathology.

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Inflammation modulates tau function in Alzheimer's disease.

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LPS induces tau phosphorylation in vivo.

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Modulation of late stage tau pathology is less clear.

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Microglial shows potential to slow spread of extracellular tau.

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A holistic approach will determine the role of inflammation in Alzheimer's disease.

Omega-3 fatty acids reduce lipopolysaccharide-induced abnormalities in expression of connexin-40 in aorta of hereditary hypertriglyceridemic rats

Omega-3 fatty acids (omega3FA) are known to reduce hypertriglyceridemia- and inflammation-induced vascular wall diseases. However, mechanisms of their effects are not completely clear. We examined, whether 10-day omega3FA diet can reduce bacterial lipopolysaccharide-induced changes in expression of gap junction protein connexin40 (Cx40) in the aorta of hereditary hypertriglyceridemic (hHTG) rats. After administration of a single dose of lipopolysaccharide (LPS, 1 mg/kg, i.p.) to adult hHTG rats, animals were fed with omega3FA diet (30 mg/kg/day) for 10 days. LPS decreased Cx40 expression that was associated with reduced acetylcholine-induced relaxation of aorta. Omega3FA administration to LPS rats had partial anti-inflammatory effects, associated with increased Cx40 expression and improved endothelium dependent relaxation of the aorta. Our results suggest that 10-day omega3FA diet could protect endothelium-dependent relaxation of the aorta of hHTG rats against LPS-induced damage through the modulation of endothelial Cx40 expression.

Urocortins and CRF receptor type 2 variants in the male rat colon: gene expression and regulation by endotoxin and anti-inflammatory effect

Urocortins (Ucns) 1, 2, and 3 and corticotropin-releasing factor receptor 2 (CRF2) mRNA are prominently expressed in various layers of the upper gut. We tested whether Ucns and CRF2 variants are also expressed in the different layers of the rat colon, regulated by LPS (100 μg/kg ip) and play a modulatory role in the colonic immune response to LPS. Transcripts of Ucns and CRF2b, the most common isoform in the periphery, were detected in all laser microdissected layers, including myenteric neurons. LPS increased the mRNA level of Ucn 1, Ucn 2, and Ucn 3 and decreased that of CRF2b in both the colonic mucosa and submucosa + muscle (S+M) layers at 2, 6, and 9 h after injection with a return to basal at 24 h. In addition, CRF2a, another variant more prominent in the brain, and a novel truncated splice variant CRF2a-3 mRNA were detected in all segments of the large intestine. LPS reciprocally regulated the colonic expression of these CRF2 variants by decreasing both CRF2a and CRF2b, while increasing CRF2a-3 in the mucosa and S+M. The CRF2 antagonist astressin2-B further enhanced LPS-induced increase of mRNA level of interleukin (IL)-1β, TNF-α, and inducible nitric oxide synthase in S+M layers and IL-1β in the mucosa and evoked TNF-α expression in the mucosa. These data indicate that Ucns/CRF2 variants are widely expressed in all colonic layers and reciprocally regulated by LPS. CRF2 signaling dampens the CD14/TLR4-mediated acute inflammatory response to Gram-negative bacteria in the colon.

Endogenous opiates and behavior: 2014

This paper is the thirty-seventh consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2014 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (endogenous opioids and receptors), and the roles of these opioid peptides and receptors in pain and analgesia (pain and analgesia); stress and social status (human studies); tolerance and dependence (opioid mediation of other analgesic responses); learning and memory (stress and social status); eating and drinking (stress-induced analgesia); alcohol and drugs of abuse (emotional responses in opioid-mediated behaviors); sexual activity and hormones, pregnancy, development and endocrinology (opioid involvement in stress response regulation); mental illness and mood (tolerance and dependence); seizures and neurologic disorders (learning and memory); electrical-related activity and neurophysiology (opiates and conditioned place preferences (CPP)); general activity and locomotion (eating and drinking); gastrointestinal, renal and hepatic functions (alcohol and drugs of abuse); cardiovascular responses (opiates and ethanol); respiration and thermoregulation (opiates and THC); and immunological responses (opiates and stimulants). This paper is the thirty-seventh consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2014 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (endogenous opioids and receptors), and the roles of these opioid peptides and receptors in pain and analgesia (pain and analgesia); stress and social status (human studies); tolerance and dependence (opioid mediation of other analgesic responses); learning and memory (stress and social status); eating and drinking (stress-induced analgesia); alcohol and drugs of abuse (emotional responses in opioid-mediated behaviors); sexual activity and hormones, pregnancy, development and endocrinology (opioid involvement in stress response regulation); mental illness and mood (tolerance and dependence); seizures and neurologic disorders (learning and memory); electrical-related activity and neurophysiology (opiates and conditioned place preferences (CPP)); general activity and locomotion (eating and drinking); gastrointestinal, renal and hepatic functions (alcohol and drugs of abuse); cardiovascular responses (opiates and ethanol); respiration and thermoregulation (opiates and THC); and immunological responses (opiates and stimulants).

Systemic inflammation in early neonatal mice induces transient and lasting neurodegenerative effects

Background

The inflammatory mediator lipopolysaccharide (LPS) has been shown to induce acute gliosis in neonatal mice. However, the progressive effects on the murine neurodevelopmental program over the week that follows systemic inflammation are not known. Thus, we investigated the effects of repeated LPS administration in the first postnatal week in mice, a condition mimicking sepsis in late preterm infants, on the developing central nervous system (CNS).

Methods

Systemic inflammation was induced by daily intraperitoneal administration (i.p.) of LPS (6 mg/kg) in newborn mice from postnatal day (PND) 4 to PND6. The effects on neurodevelopment were examined by staining the white matter and neurons with Luxol Fast Blue and Cresyl Violet, respectively. The inflammatory response was assessed by quantifying the expression/activity of matrix metalloproteinases (MMP), toll-like receptor (TLR)-4, high mobility group box (HMGB)-1, and autotaxin (ATX). In addition, B6 CX3CR1^gfp/+ mice combined with cryo-immunofluorescence were used to determine the acute, delayed, and lasting effects on myelination, microglia, and astrocytes.

Results

LPS administration led to acute body and brain weight loss as well as overt structural changes in the brain such as cerebellar hypoplasia, neuronal loss/shrinkage, and delayed myelination. The impaired myelination was associated with alterations in the proliferation and differentiation of NG2 progenitor cells early after LPS administration, rather than with excessive phagocytosis by CNS myeloid cells. In addition to disruptions in brain architecture, a robust inflammatory response to LPS was observed. Quantification of inflammatory biomarkers revealed decreased expression of ATX with concurrent increases in HMGB1, TLR-4, and MMP-9 expression levels. Acute astrogliosis (GFAP⁺ cells) in the brain parenchyma and at the microvasculature interface together with parenchymal microgliosis (CX3CR1⁺ cells) were also observed. These changes preceded the migration/proliferation of CX3CR1⁺ cells around the vessels at later time points and the subsequent loss of GFAP⁺ astrocytes.

Conclusion

Collectively, our study has uncovered a complex innate inflammatory reaction and associated structural changes in the brains of neonatal mice challenged peripherally with LPS. These findings may explain some of the neurobehavioral abnormalities that develop following neonatal sepsis.

The over-production of TNF-α via Toll-like receptor 4 in spinal dorsal horn contributes to the chronic postsurgical pain in rat

PURPOSE

Many patients suffer from chronic postsurgical pain (CPSP) following surgery, and the underlying mechanisms are poorly understood. In the present work, using the skin/muscle incision retraction (SMIR) model, the role of spinal TLR4/TNF-α pathway in the induction of CPSP was evaluated.

METHODS

Mechanical allodynia induced by SMIR was established in adult male Sprague-Dawley rats. The von Frey test was performed to evaluate the role of TLR4/TNF-α pathway on the mechanical allodynia. Western-blot and immunohistochemistry methods were adopted to understand the molecular mechanisms.

RESULTS

SMIR surgery decreased the ipsilateral 50 % paw withdrawal threshold, lasting for at least 20 days. Western-blot analysis and immunohistochemistry revealed that SMIR surgery significantly upregulated the expression of TLR4 (p < 0.01) in glial cells on the ipsilateral side of spinal cord and increased TLR4 occurred on day 5 and was maintained to the end of the experiment (day 20). Similarly, tumor necrosis factor-alpha (TNF-α) was significantly increased on days 5, 10, and 20 on the ipsilateral side of spinal dorsal horn following SMIR surgery. Intraperitoneal injection of an inhibitor of TNF-α synthesis thalidomide at 50 or 100 mg/kg dose (but not 10 mg/kg dose) significantly ameliorated the reduced paw withdrawal threshold induced by SMIR surgery. Importantly, intrathecal delivery of a specific TLR4 antagonist (LPS-RS) at dose of 25 μg significantly attenuated mechanical allodynia and prevented the upregulation of TNF-α induced by SMIR surgery.

CONCLUSIONS

These findings suggest that the upregulation of TNF-α via TLR4 contributes to the development of CPSP in spinal dorsal horn.

The reproducibility of biomedical research: Sleepers awake!

There is increasing concern about the reliability of biomedical research, with recent articles suggesting that up to 85% of research funding is wasted. This article argues that an important reason for this is the inappropriate use of molecular techniques, particularly in the field of RNA biomarkers, coupled with a tendency to exaggerate the importance of research findings.