Small-dose capsaicin reduces systemic inflammatory responses in septic rats

Single-cell RNA sequencing reveals the effects of capsaicin in the treatment of sepsis-induced liver injury

Sepsis is a difficult-to-treat systemic condition in which liver dysfunction acts as both regulator and target. However, the dynamic response of diverse intrahepatic cells to sepsis remains poorly characterized. Capsaicin (CAP), a multifunctional chemical derived from chilli peppers, has recently been shown to potentially possess anti-inflammatory effects, which is also one of the main approaches for drug discovery against sepsis. We performed single-cell RNA transcriptome sequencing on 86,830 intrahepatic cells isolated from normal mice, cecal ligation and puncture-induced sepsis model mice and CAP-treated mice. The transcriptional atlas of these cells revealed dynamic changes in hepatocytes, macrophages, neutrophils, and endothelial cells in response to sepsis. Among the extensive crosstalk across these major subtypes, KC_Cxcl10 shared strong potential interaction with other cells when responding to sepsis. CAP mitigated the severity of inflammation by partly reversing these pathophysiologic processes. Specific cell subpopulations in the liver act collectively to escalate inflammation, ultimately causing liver dysfunction. CAP displays its health-promoting function by ameliorating liver dysfunction induced by sepsis. Our study provides valuable insights into the pathophysiology of sepsis and suggestions for future therapeutic gain.

Radioprotective Effects of Carvacrol and/or Thymol against Gamma Irradiation-Induced Acute Nephropathy: In Silico and In Vivo Evidence of the Involvement of Insulin-like Growth Factor-1 (IGF-1) and Calcitonin Gene-Related Peptide

Radiotherapy (RT) is an effective curative cancer treatment. However, RT can seriously damage kidney tissues resulting in radiotherapy nephropathy (RN) where oxidative stress, inflammation, and apoptosis are among the common pathomechanisms. Carvacrol and thymol are known for their antioxidative, anti-inflammatory, and radioprotective activities. Therefore, this study investigated the nephroprotective potentials of carvacrol and/or thymol against gamma (γ) irradiation-induced nephrotoxicity in rats along with the nephroprotection mechanisms, particularly the involvement of insulin-like growth factor-1 (IGF-1) and calcitonin gene-related peptide (CGRP). Methods: Male rats were injected with carvacrol and/or thymol (80 and 50 mg/kg BW in the vehicle, respectively) for five days and exposed to a single dose of irradiation (6 Gy). Then, nephrotoxicity indices, oxidative stress, inflammatory, apoptotic biomarkers, and the histopathological examination were assessed. Also, IGF-1 and CGRP renal expressions were measured. Results: Carvacrol and/or thymol protected kidneys against γ-irradiation-induced acute RN which might be attributed to their antioxidative, anti-inflammatory, and antiapoptotic activities. Moreover, both reserved the γ -irradiation-induced downregulation of CGRP- TNF-α loop in acute RN that might be involved in the pathomechanisms of acute RN. Additionally, in Silico molecular docking simulation of carvacrol and thymol demonstrated promising fitting and binding with CGRP, IGF-1, TNF-α and NF-κB through the formation of hydrogen, hydrophobic and alkyl bonds with binding sites of target proteins which supports the reno-protective properties of carvacrol and thymol. Collectively, our findings open a new avenue for using carvacrol and/or thymol to improve the therapeutic index of γ-irradiation.

Does Transient Receptor Potential Vanilloid Type 1 Alleviate or Aggravate Pathological Myocardial Hypertrophy?

Transient receptor potential vanilloid type 1 (TRPV1) is a non-selective cation channel, which is involved in the endogenous stress adaptation mechanism for protection of the heart as well as the occurrence and development of some heart diseases. Although the effect of activation of the TRPV1 channel on different types of non-neural cells in the heart remains unclear, most data show that stimulation of sensory nerves expressing TRPV1 or stimulation/overexpression of the TRPV1 channel has a beneficial role in heart disease. Some studies have proven that TRPV1 has an important relationship with pathological myocardial hypertrophy, but the specific mechanism and effect are not clear. In order to help researchers better understand the relationship between TRPV1 and pathological myocardial hypertrophy, this paper aims to summarize the effect of TRPV1 and the related mechanism in the occurrence and development of pathological myocardial hypertrophy from the following three points of view: 1) role of TRPV1 in alleviation of pathological myocardial hypertrophy; 2) role of TRPV1 in aggravation of pathological myocardial hypertrophy; and 3) the point of view of our team of researchers. It is expected that new therapies can provide potential targets for pathological myocardial hypertrophy.

Capsaicin and Gut Microbiota in Health and Disease

Capsaicin is a widespread spice known for its analgesic qualities. Although a comprehensive body of evidence suggests pleiotropic benefits of capsaicin, including anti-inflammatory, antioxidant, anti-proliferative, metabolic, or cardioprotective effects, it is frequently avoided due to reported digestive side-effects. As the gut bacterial profile is strongly linked to diet and capsaicin displays modulatory effects on gut microbiota, a new hypothesis has recently emerged about its possible applicability against widespread pathologies, such as metabolic and inflammatory diseases. The present review explores the capsaicin–microbiota crosstalk and capsaicin effect on dysbiosis, and illustrates the intimate mechanisms that underlie its action in preventing the onset or development of pathologies like obesity, diabetes, or inflammatory bowel diseases. A possible antimicrobial property of capsaicin, mediated by the beneficial alteration of microbiota, is also discussed. However, as data are coming mostly from experimental models, caution is needed in translating these findings to humans.

TRPV1 Activation Prevents Renal Ischemia-Reperfusion Injury-Induced Increase in Salt Sensitivity by Suppressing Renal Sympathetic Nerve Activity

Abstract: Background

Salt sensitivity is increased following renal Ischemia-Reperfusion (I/R) injury. We tested the hypothesis that high salt intake induced increase in Renal Sympathetic Nerve Activity (RSNA) after renal I/R can be prevented by activation of Transient Receptor Potential Vanilloid 1 (TRPV1).

Methods

Rats were fed a 0.4% NaCl diet for 5 weeks after renal I/R, followed by a 4% NaCl diet for 4 more weeks in four groups: sham, I/R, I/R +High Dose Capsaicin (HDC), and I/R+Low Dose Capsaicin (LDC). The low (1mg/kg) or high (100mg/kg) dose of capsaicin was injected subcutaneously before I/R to activate or desensitize TRPV1, respectively.

Results

Systolic blood pressure was gradually elevated after fed on a high-salt diet in the I/R and I/R+HDC groups but not in the I/R+LDC group, with a greater increase in the I/R+HDC group. Renal function was impaired in the I/R group and was further deteriorated in the I/R+HDC group but was unchanged in the I/R+LDC group. At the end of high salt treatment, afferent renal nerve activity in response to unilateral intra-pelvic administration of capsaicin was decreased in the I/R group and was further suppressed in the I/R+HDC group but was unchanged in the I/R+LDC group. RSNA in response to intrathecal administration of muscimol, a selective agonist of GABA-A receptors, was augmented in the I/R group and further intensified in the I/R+HDC group but was unchanged in the I/R+LDC group. Similarly, urinary norepinephrine levels were increased in the I/R group and were further elevated in the I/R+HDC group but unchanged in the I/R+LDC group.

Conclusion

These data suggest that TRPV1 activation prevents renal I/R injury-induced increase in salt sensitivity by suppressing RSNA.

Involvement of Neural Transient Receptor Potential Channels in Peripheral Inflammation

Transient receptor potential (TRP) channels are a superfamily of non-selective cation channels that act as polymodal sensors in many tissues throughout mammalian organisms. In the context of ion channels, they are unique for their broad diversity of activation mechanisms and their cation selectivity. TRP channels are involved in a diverse range of physiological processes including chemical sensing, nociception, and mediating cytokine release. They also play an important role in the regulation of inflammation through sensory function and the release of neuropeptides. In this review, we discuss the functional contribution of a subset of TRP channels (TRPV1, TRPV4, TRPM3, TRPM8, and TRPA1) that are involved in the body’s immune responses, particularly in relation to inflammation. We focus on these five TRP channels because, in addition to being expressed in many somatic cell types, these channels are also expressed on peripheral ganglia and nerves that innervate visceral organs and tissues throughout the body. Activation of these neural TRP channels enables crosstalk between neurons, immune cells, and epithelial cells to regulate a wide range of inflammatory actions. TRP channels act either through direct effects on cation levels or through indirect modulation of intracellular pathways to trigger pro- or anti-inflammatory mechanisms, depending on the inflammatory disease context. The expression of TRP channels on both neural and immune cells has made them an attractive drug target in diseases involving inflammation. Future work in this domain will likely yield important new pathways and therapies for the treatment of a broad range of disorders including colitis, dermatitis, sepsis, asthma, and pain.

Capsaicin Exerts Anti-convulsant and Neuroprotective Effects in Pentylenetetrazole-Induced Seizures

The transient receptor potential vanilloid-1 (TRPV1) receptor has been implicated in the development of epileptic seizures. We examined the effect of the TRPV1 agonist capsaicin on epileptic seizures, neuronal injury and oxidative stress in a model of status epilepticus induced in the rat by intraperitoneal (i.p.) injections of pentylenetetrazole (PTZ). Capsaicin was i.p. given at 1 or 2 mg/kg, 30 min before the first PTZ injection. Other groups were i.p. treated with the vehicle or the anti-epileptic drug phenytoin (30 mg/kg) alone or co-administered with capsaicin at 2 mg/kg. Brain levels of malondialdehyde (MDA), reduced glutathione (GSH), nitric oxide, and paraoxonase-1 (PON-1) activity, seizure scores, latency time and PTZ dose required to reach status epilepticus were determined. Histopathological assessment of neuronal damage was done. Results showed that brain MDA decreased by treatment with capsaicin, phenytoin or capsaicin/phenytoin. Nitric oxide decreased by capsaicin or capsaicin/phenytoin. GSH and PON-1 activity increased after capsaicin, phenytoin or capsaicin/phenytoin. Mean total seizure score decreased by 48.8% and 66.3% by capsaicin compared with 78.7% for phenytoin and 69.8% for capsaicin/phenytoin treatment. Only phenytoin increased the latency (115.7%) and threshold dose of PTZ (78.3%). Capsaicin did not decrease the anti-convulsive effect of phenytoin but prevented the phenytoin-induced increase in latency time and threshold dose. Neuronal damage decreased by phenytoin or capsaicin at 2 mg/kg but almost completely prevented by capsaicin/phenytoin. Thus in this model of status epilepticus, capsaicin decreased brain oxidative stress, the severity of seizures and neuronal injury and its co-administration with phenytoin afforded neuronal protection.

Neuroinflammation and Cytokines in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS): A Critical Review of Research Methods

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is the label given to a syndrome that can include long-term flu-like symptoms, profound fatigue, trouble concentrating, and autonomic problems, all of which worsen after exertion. It is unclear how many individuals with this diagnosis are suffering from the same condition or have the same underlying pathophysiology, and the discovery of biomarkers would be clarifying. The name "myalgic encephalomyelitis" essentially means "muscle pain related to central nervous system inflammation" and many efforts to find diagnostic biomarkers have focused on one or more aspects of neuroinflammation, from periphery to brain. As the field uncovers the relationship between the symptoms of this condition and neuroinflammation, attention must be paid to the biological mechanisms of neuroinflammation and issues with its potential measurement. The current review focuses on three methods used to study putative neuroinflammation in ME/CFS: (1) positron emission tomography (PET) neuroimaging using translocator protein (TSPO) binding radioligand (2) magnetic resonance spectroscopy (MRS) neuroimaging and (3) assays of cytokines circulating in blood and cerebrospinal fluid. PET scanning using TSPO-binding radioligand is a promising option for studies of neuroinflammation. However, methodological difficulties that exist both in this particular technique and across the ME/CFS neuroimaging literature must be addressed for any results to be interpretable. We argue that the vast majority of ME/CFS neuroimaging has failed to use optimal techniques for studying brainstem, despite its probable centrality to any neuroinflammatory causes or autonomic effects. MRS is discussed as a less informative but more widely available, less invasive, and less expensive option for imaging neuroinflammation, and existing studies using MRS neuroimaging are reviewed. Studies seeking to find a peripheral circulating cytokine "profile" for ME/CFS are reviewed, with attention paid to the biological and methodological reasons for lack of replication among these studies. We argue that both the biological mechanisms of cytokines and the innumerable sources of potential variance in their measurement make it unlikely that a consistent and replicable diagnostic cytokine profile will ever be discovered.

Endogenously generated arachidonate-derived ligands for TRPV1 induce cardiac protection in sepsis

The severity of cardiac dysfunction predicts mortality in sepsis. Activation of transient receptor potential vanilloid receptor type (TRPV)-1, a predominantly neuronal nonselective cation channel, has been shown to improve outcome in sepsis and endotoxemia. However, the role of TRPV1 and the identity of its endogenous ligands in the cardiac dysfunction caused by sepsis and endotoxemia are unknown. Using TRPV1^-/- and TRPV1^+/+ mice, we showed that endogenous activation of cardiac TRPV1 during sepsis is key to limiting the ensuing cardiac dysfunction. Use of liquid chromatography-tandem mass spectrometry lipid analysis and selective inhibitors of arachidonic metabolism suggest that the arachidonate-derived TRPV1 activator, 20-hydroxyeicosateraenoic acid (20-HETE), underlies a substantial component of TRPV1-mediated cardioprotection in sepsis. Moreover, using selective antagonists for neuropeptide receptors, we show that this effect of TRPV1 relates to the activity of neuronally released cardiac calcitonin gene-related peptide (CGRP) and that, accordingly, administration of CGRP can rescue cardiac dysfunction in severe endotoxemia. In sum activation of TRPV1 by 20-HETE leads to the release of CGRP, which protects the heart against the cardiac dysfunction in endotoxemia and identifies both TRPV1 and CGRP receptors as potential therapeutic targets in endotoxemia.-Chen, J., Hamers, A. J. P., Finsterbusch, M., Massimo, G., Zafar, M., Corder, R., Colas, R. A., Dalli, J., Thiemermann, C., Ahluwalia, A. Endogenously generated arachidonate-derived ligands for TRPV1 induce cardiac protection in sepsis.

Involvement of TRPV1 in the expression and release of calcitonin gene-related peptide induced by rutaecarpine

The traditional Chinese herb Wu-Chu-Yu has been used to treat hypertension for hundreds of years. A previous study indicated that rutaecarpine was the effective component of Wu-Chu-Yu, which lowered blood pressure by elevating the expression level of calcitonin gene-related peptide (CGRP). The present study was performed to investigate the role of transient receptor potential cation channel subfamily V member 1 (TRPV1) in CGRP expression and release induced by rutaecarpine. Dorsal root ganglia (DRG) obtained from Sprague-Dawley rats were cultured to analyze the mRNA expression and release of CGRP. Calcium influx, as an indicator of TRPV1 activation, was measured in 293 cells with stable overexpression of TRPV1. The results demonstrated that the amount of CGRP in the cell culture supernatant and the mRNA expression of CGRPα and CGRPβ in DRG was upregulated by rutaecarpine in a concentration-dependent manner, and was inhibited by the TRPV1 receptor antagonist capsazepine. In addition, intracellular Ca²⁺ levels were increased by Rut in the aforementioned 293 cell line, indicating the activation of TRPV1 by Rut. Therefore, it was concluded that TRPV1 was involved in the expression and release of CGRP stimulated by rutaecarpine, which provided novel mechanistic understanding of the treatment of hypertension using the Chinese herb Wu-Chu-Yu.

Research progress of capsaicin responses to various pharmacological challenges

Capsaicin, a well known vanilloid, has shown evidence of an ample variety of biological effects which make it the target of extensive research ever since its identification. In spite of the fact that capsaicin causes health hazards in quite a few ways, yet, the verity cannot be ignored that capsaicin has several therapeutic implications. In patients with hypersensitive bladders, vesical instillation of 1 mM capsaicin markedly improved urinary frequency and urge incontinence. Again, administration of capsaicin favors an augmentation in lipid mobilization and a decrease in adipose tissue mass. Topical capsaicin cream as well decreases postsurgical neuropathic pain and is preferred by patients over a placebo among other therapies. Several in vitro studies have revealed that capsaicin results in growth arrest in some transformed cell lines. Furthermore, capsaicin has been proven to be an undeniably exciting molecule and remains a valuable drug for alleviating pain and itch. It has been recognized that capsaicinoids are the most potential agonists of capsaicin receptor (TRPV1). However, vanilloids could exert the beneficial effects not only through the receptor-dependent pathway but also through the receptor-independent one. The involvement of serotonin, neuropeptide Substance P and somatostatin in the pharmacological actions of capsaicin has been expansively investigated. Better understanding of the established TRPV1 receptor mechanism as well as exploring other possible receptor mechanism may publicize other new clinical efficacies of capsaicin. Further, clinical studies are required in several of these conditions to establish the efficacy of capsaicin.

Novel Approaches to Extraction Methods in Recovery of Capsaicin from Habanero Pepper (CNPH 15.192)

Introduction:

The objective of this study was to compare three capsaicin extraction methods: Shoxlet, Ultrasound-assisted Extraction (UAE), and Shaker-assisted Extraction (SAE) from Habanero pepper, CNPH 15.192.

Materials and Methods:

The different parameters evaluated were alcohol degree, time extraction, and solid–solvent ratio using response surface methodology (RSM).

Results:

The three parameters found significant (p < 0.05) were for UAE and solvent concentration and extraction time for SAE. The optimum conditions for the capsaicin UAE and SAE were similar 95% alcohol degree, 30 minutes and solid–liquid ratio 2 mg/mL. The Soxhlet increased the extraction in 10–25%; however, long extraction times (45 minutes) degraded 2% capsaicin.

Conclusion:

The extraction of capsaicin was influenced by extraction method and by the operating conditions chosen. The optimized conditions provided savings of time, solvent, and herbal material. Prudent choice of the extraction method is essential to ensure optimal yield of extract, thereby making the study relevant and the knowledge gained useful for further exploitation and application of this resource.

SUMMARY

Habanero pepper, line CNPH 15.192, possess capsaicin in higher levels when compared with others species

Higher levels of ethanolic strength are more suitable to obtain a higher levels of capsaicin

Box-Behnken design indicates to be useful to explore the best conditions of ultrasound assisted extraction of capsaicin.

Abbreviations used: Nomenclature UAE: Ultrasound-assisted Extraction; SAE: Shaker-assisted Extraction.

Pharmacological inhibition of FAAH modulates TLR-induced neuroinflammation, but not sickness behaviour: An effect partially mediated by central TRPV1

Aberrant activation of toll-like receptors (TLRs), key components of the innate immune system, has been proposed to underlie and exacerbate a range of central nervous system disorders. Increasing evidence supports a role for the endocannabinoid system in modulating inflammatory responses including those mediated by TLRs, and thus this system may provide an important treatment target for neuroinflammatory disorders. However, the effect of modulating endocannabinoid tone on TLR-induced neuroinflammation in vivo and associated behavioural changes is largely unknown. The present study examined the effect of inhibiting fatty acid amide hydrolyase (FAAH), the primary enzyme responsible for the metabolism of anandamide (AEA), in vivo on TLR4-induced neuroimmune and behavioural responses, and evaluated sites and mechanisms of action. Systemic administration of the FAAH inhibitor PF3845 increased levels of AEA, and related FAAH substrates N-oleoylethanolamide (OEA) and N-palmitoylethanolamide (PEA), in the frontal cortex and hippocampus of rats, an effect associated with an attenuation in the expression of pro- and anti-inflammatory cytokines and mediators measured 2hrs following systemic administration of the TLR4 agonist, lipopolysaccharide (LPS). These effects were mimicked by central i.c.v. administration of PF3845, but not systemic administration of the peripherally-restricted FAAH inhibitor URB937. Central antagonism of TRPV1 significantly attenuated the PF3845-induced decrease in IL-6 expression, effects not observed following antagonism of CB_1, CB₂, PPARα, PPARγ or GPR55. LPS-induced a robust sickness-like behavioural response and increased the expression of markers of glial activity and pro-inflammatory cytokines over 24hrs. Systemic administration of PF3845 modulated the TLR4-induced expression of neuroimmune mediators and anhedonia without altering acute sickness behaviour. Overall, these findings support an important role for FAAH substrates directly within the brain in the regulation of TLR4-associated neuroinflammation and highlight a role for TRPV1 in partially mediating these effects.

Host-mediated effects of phytonutrients in ruminants: A review

Plants produce an extensive array of organic compounds derived from secondary metabolism that may be useful in animal nutrition because of their chemical makeup. These plant-derived bioactive compounds, also referred to as phytonutrients (PN) or phytobiotics, have been shown to express antimicrobial activities against a wide range of bacteria, yeast, and fungi and have been investigated as rumen modifiers in ruminant nutrition. Studies have reported that PN may inhibit deamination of AA and methanogenesis in the rumen and shift fermentation toward propionate and butyrate. Most of the experiments, however, have been conducted in vitro, and responses have been highly variable and inconsistent in animal experiments. In addition, some studies have reported that PN had positive effects on productivity, although rumen fermentation was not affected. Other than antimicrobial effects in the gut, PN are known to bind specific receptors expressed in neurons, intestines, and other cells and exhibit related physiological effects in nonruminants. The receptor-mediated effects include immune responses, oxidative stress, and insulin secretion and activity. Some PN, due to their phenolic nature, are likely less susceptible to microbial degradation in the rumen and may exhibit activities postruminally, similar to their mode of action in nonruminant species. This opens a new area of research in ruminants, including effects of PN on the animal's immune system, postruminal nutrient use, and animal physiology. Although limited, studies with ruminants provide first evidence of PN's regulatory effects on the host responses. For example, PN were reported to regulate immune cells related to adaptive and innate immunity in challenged or nonchallenged dairy cows. Supplementation of PN reduced oxidative stress by decreasing lipid peroxidation and increasing endogenous antioxidants in ruminants. Additionally, insulin secretion and sensitivity were reportedly regulated by PN in dairy cows. The regulatory effects of PN on immunity may be beneficial for immune suppression and inflammation in dairy cows. In addition, PN could positively affect energy partitioning for milk production through their effects on insulin secretion and sensitivity. Further research is needed to elucidate the effect and mode of action of PN on immune function and animal energetics.

Effects of rumen-protected Capsicum oleoresin on productivity and responses to a glucose tolerance test in lactating dairy cows

The objective of this experiment was to investigate the effects of rumen-protected Capsicum oleoresin (RPC) supplementation on feed intake, milk yield and composition, nutrient utilization, fecal microbial ecology, and responses to a glucose tolerance test in lactating dairy cows. Nine multiparous Holstein cows were used in a replicated 3 × 3 Latin square design balanced for residual effects with three 28-d periods. Each period consisted of 14 d for adaptation and 14 d for data collection and sampling. Treatments were 0 (control), 100, and 200 mg of RPC/cow per day. They were mixed with a small portion of the total mixed ration and top-dressed. Glucose tolerance test was conducted once during each experimental period by intravenous administration of glucose at a rate of 0.3 g/kg of body weight. Dry matter intake was not affected by RPC. Milk yield tended to increase for RPC treatments compared to the control. Feed efficiency was linearly increased by RPC supplementation. Concentrations of fat, true protein, and lactose in milk were not affected by RPC. Apparent total-tract digestibility of dry matter, organic matter, and crude protein was linearly increased, and fecal nitrogen excretion was linearly decreased by RPC supplementation. Rumen-protected Capsicum oleoresin did not affect the composition of fecal bacteria. Glucose concentration in serum was not affected by RPC supplementation post glucose challenge. However, compared to the control, RPC decreased serum insulin concentration at 5, 10, and 40 min post glucose challenge. The area under the insulin concentration curve was also decreased 25% by RPC. Concentration of nonesterified fatty acids and β-hydroxybutyrate in serum were not affected by RPC following glucose administration. In this study, RPC tended to increase milk production and increased feed efficiency in dairy cows. In addition, RPC decreased serum insulin concentration during the glucose tolerance test, but glucose concentration was not affected by treatment.

26-Week Dermal Oncogenicity Study Evaluating Pure trans-Capsaicin in Tg.AC Hemizygous Mice (FBV/N)

The objective of this study was to assess the oncogenic potential of trans-capsaicin when administered weekly via topical application to the dorsal skin of Tg.AC mice for 26 weeks. Male and female Tg.AC mice (25 mice/sex/group) received dose formulations containing trans-capsaicin dissolved in diethylene glycol monoethyl ether (DGME). The positive control was tetradecanoylphorbol-13-acetate (TPA) dissolved in DGME. Appropriate controls, including a topical lidocaine local anesthetic pretreatment (4% w/ w), were maintained. All groups were dosed once weekly, except for the TPA group, which was dosed twice per week. Analysis of the macroscopic observations after the final sacrifice revealed no noteworthy treatment-related findings, with the exception of dermal masses that were randomly dispersed throughout all treatment groups for both males and females. The frequency of dermal masses in the capsaicin-treated groups (at a dose level of up to 102 mg/kg and an application rate of 25.6 mg/cm2/kg/week) was not elevated in comparison to either concurrent vehicle or untreated controls. In contrast, a notable increase in the frequency of dermal masses was observed in the TPA-treated mice compared to both the concurrent vehicle and untreated controls. Dermal application of capsaicin resulted in no increased incidence of preneoplastic or neoplastic skin lesions. In contrast, over half the male and female mice exposed to TPA had multiple skin papillomas; the majority of the TPA-treated animals either died early or was humanely euthanized due to tumor load. Spontaneously occurring neoplasms were not appreciably increased in capsaicin-treated animals. Capsaicin-related non-neoplastic microscopic findings were seen sporadically in both genders and included acanthosis, hyperkeratosis/parakeratosis (primarily females), epidermal crusts, subepidermal fibrosis, epidermal ulcerations/erosions, and chronic-active inflammation. There was no evidence of a dose response in either the incidence or severity of these findings. The lidocaine- (at a dose level of 162 mg/kg and at an application rate of 40.5 mg/cm2/kg/week) and DGME-treated (at a dose level of 4.0 g/kg and at an application rate of 1 g/cm2/kg/week) control groups also did not display any evidence of increase in dermal masses. Based on these results, trans-capsaicin, lidocaine, and DGME should be considered nononcogenic in the Tg.AC mouse dermal model.

Capsaicin Modulates the Immune Cross Talk Between Human Mononuclears and Cells from Two Colon Carcinoma Lines

BACKGROUND

Capsaicin, the pungent alkaloid of the chili peppers, has gained a worldwide reputation. In addition to its culinary assets, capsaicin possesses analgesic, anti-inflammatory, antimicrobial, and even carcinopreventive properties. Considering the linkage between chronic inflammation and tumorigenesis, the aim of the study was to evaluate the role of capsaicin in the immune interplay between human peripheral blood mononuclear cells (PBMCs) and HT-29 or RKO cells from human colon carcinoma lines.

METHODS

PBMCs were incubated for 24 hours with either HT-29 or RKO cells and concentrations of capsaicin ranging between 10 and 200 µM. Subsequently, the generation of the following cytokines was examined: tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, interferon (IFN)-γ, IL-1ra, and IL-10.

RESULTS

Capsaicin caused a concentration-dependent inhibition of colon cancer cells proliferation but had no effect on PBMC viability. 200 µM of capsaicin suppressed the production of all cytokines tested. At lower concentrations, the secretion of TNF-α, IL-1β, IFN-γ, IL-10, and IL-1ra was inhibited concentration-dependently, whereas that of IL-6 was stimulated.

CONCLUSIONS

Capsaicin causes a concentration-dependent alteration of the immune balance between PBMC and colon carcinoma cells expressed as an inhibited generation of inflammatory cytokines. These findings indicate the existence of an additional immunomodulatory mechanism by which this alkaloid may prevent tumor development.

Neuroimmunity: Physiology and Pathology

Evolution has yielded multiple complex and complementary mechanisms to detect environmental danger and protect tissues from damage. The nervous system rapidly processes information and coordinates complex defense behaviors, and the immune system eliminates diverse threats by virtue of mobile, specialized cell populations. The two systems are tightly integrated, cooperating in local and systemic reflexes that restore homeostasis in response to tissue injury and infection. They further share a broad common language of cytokines, growth factors, and neuropeptides that enables bidirectional communication. However, this reciprocal cross talk permits amplification of maladaptive feedforward inflammatory loops that contribute to the development of allergy, autoimmunity, itch, and pain. Appreciating the immune and nervous systems as a holistic, coordinated defense system provides both new insights into inflammation and exciting opportunities for managing acute and chronic inflammatory diseases.

TRPA1 mediates the effects of hypothermia on the monocyte inflammatory response

INTRODUCTION

Hypothermia is a well-known risk factor for postoperative complications because it prolongs the monocyte inflammatory response. The purpose of this study was to investigate whether temperature-activated ion channels (transient receptor protein channels [TRP] A1 and V1) mediate the effects of temperature on monocytes.

METHODS

Primary human monocytes were isolated and stimulated with lipopolysaccharide at 32°C or 39°C. RNA was isolated for analysis of microRNA (miR)-155 expression, and cytokines in the supernatant were measured with an enzyme-linked immunosorbent assay. Specific inhibitors of TRPA1 (HC- 030031) and a specific activator of TRPV1 (capsaicin) were used to block or activate TRPA1 and TRPV1, respectively. Statistical analysis was performed using the Wilcoxon signed-rank test.

RESULTS

TRPM8 mRNA was not expressed in primary human monocytes, whereas TRPA1 and TRPV1 were expressed. TRPV1 mRNA expression was suppressed at 32°C but not at 39°C. TRPA1 was induced strongly at 32°C and 39°C. Immunofluorescence microscopy confirmed that monocytes express TRPA1 and TRPV1 on their cell surface. Interleukin-10 secretion was increased by blocking TRPA1 (77.8 ± 3 2.8 pg/mL) and activating TRPA1 (79.4 ± 16.1 pg/mL) after 24 hours at 32°C (control 37.4 ± 17.1 pg/mL, P < .05). At 36 hours, tumor necrosis factor secretion was decreased after TRPA1 blockade (2,321 ± 439 pg/mL) and TRPV1 activation (2,137 ± 411 pg/mL) compared with control (2,567 ± 495 pg/mL, P < .05). Furthermore, miR-155 expression also was suppressed at 24 hours by TRPA1 blockade and TRPV1 activation (both P < .05). Silencing of TRPA1 normalized monocyte IL-10 secretion at 32°C.

CONCLUSION

These results demonstrate that hypothermia mediates its effects on monocytes through TRPA1. Blockade of TRPA1 or activation of TRPV1 may be used to modify the effects of hypothermia on the monocyte inflammatory response.

The effect of capsaicin on circulating biomarkers, soluble tumor necrosis factor and soluble tumor necrosis factor-receptor-1 and -2 levels in vivo using lipopolysaccharide-treated mice

The circulating soluble tumor necrosis factor (sTNF) and sTNF-receptor (R) 1 and -R2 have known as septic biomarker. The pungent component of capsicum, capsaicin (Cap), has several associated physiological activities, including anti-oxidant, anti-bacterial and anti-inflammatory effects. The aim of this study was to elucidate the effect of Cap on circulating sTNF and sTNF-R1 and -R2 in vivo using lipopolysaccharide (LPS)-treated mice. LPS (20 mg/kg, ip)-treated group was significantly increased circulating sTNF, sTNF-R1, and -R2 and TNF-α mRNA expression levels compared to the vehicle group. Treatment with LPS (20 mg/kg, ip) + Cap (4 mg/kg, sc)-treated group was significantly decreased both circulating sTNF levels (after 1 h only) and TNF-α mRNA expression (after 6 h) compared to the LPS-treated group. There is an early increase in circulating sTNF, sTNR-R1, and -R2 observed in the LPS-treated mice. Since Cap inhibits this initial increase as biomarkers, circulating sTNF, it is considered a potent treatment option for TNF-α-related diseases, such as septicemia. In conclusion, Cap interferes with TNF-α mRNA transcription and exerts an inhibiting effect on TNF-α release from macrophages in the early phase after LPS stimulation. Thus, Cap is considered a potent agent for the treatment of TNF-α-related diseases, such as septicemia.

Calcitonin gene-related peptide is a key neurotransmitter in the neuro-immune axis

The question of how the neural and immune systems interact in host defense is important, integrating a system that senses the whole body with one that protects. Understanding the mechanisms and routes of control could produce novel and powerful ways of promoting and enhancing normal functions as well as preventing or treating abnormal functions. Fragmentation of biological research into specialities has resulted in some failures in recognizing and understanding interactions across different systems and this is most striking across immunology, hematology, and neuroscience. This reductionist approach does not allow understanding of the in vivo orchestrated response generated through integration of all systems. However, many factors make the understanding of multisystem cross-talk in response to a threat difficult, for instance the nervous and immune systems share communication molecules and receptors for a wide range of physiological signals. But, it is clear that physical, hard-wired connections exist between the two systems, with the key link involving sensory, unmyelinated nerve fibers (c fibers) containing the neuropeptide calcitonin gene-related peptide (CGRP), and modified macrophages, mast cells and other immune and host defense cells in various locations throughout the body. In this review we will therefore focus on the induction of CGRP and its key role in the neuroimmune axis.

Capsaicin inhibits Porphyromonas gingivalis growth, biofilm formation, gingivomucosal inflammatory cytokine secretion, and in vitro osteoclastogenesis

The prevention and treatment of periodontitis requires not only the control of causative pathogens, especially Porphyromonas gingivalis, but also the regulation of inflammatory immune response. Investigating auxiliary drugs for periodontitis during conventional treatments is, thus, quite important. Capsaicin, an agonist for the vanilloid receptor subtype 1 (TRPV1), due to its bacteriostatic activity against Gram-negative bacteria and anti-inflammatory effects, appears to be a promising drug. In this work, the antimicrobial activity of capsaicin against P. gingivalis and biofilm formation, inflammatory cytokine levels in experimental periodontitis, osteoclast precursor proliferation, and osteoclastogenesis in vitro were fully investigated. The results showed that capsaicin inhibited P. gingivalis growth with a minimum inhibitory concentration (MIC) and a minimum bactericidal concentration (MBC) of 16 and 64 mg/l, respectively. Capsaicin also inhibited P. gingivalis biofilm formation, with minimum biofilm inhibition concentrations MBIC50 and MBIC90 of 16 and 32 mg/l, respectively, and reduced pre-formed biofilms' viability with a minimum biofilm reduction concentration MBRC50 of 64 mg/l, as demonstrated by confocal laser scanning microscopy. In experimental periodontitis, except for IL-10, TNF-α, IL-1β, IL-6, IL-12, and iNOS were depressed after capsaicin treatment. Moreover, capsaicin also suppressed osteoclast precursor proliferation and osteoclastogenesis, as demonstrated by NF-ĸB p65. However, this favorable effect was attenuated by the TRPV1 antagonist, camphor. It, thus, suggests that capsaicin is a potential drug for the auxiliary treatment of periodontitis. TRPV1 activation may involve in beneficial roles of capsaicin on periodontitis.

N-octanoyl-dopamine is an agonist at the capsaicin receptor TRPV1 and mitigates ischemia-induced [corrected] acute kidney injury in rat

Since stimulation of transient receptor potential channels of the vanilloid receptor subtype 1 (TRPV1) mitigates acute kidney injury (AKI) and endogenous N-acyl dopamine derivatives are able to activate TRPV1, we tested if synthetic N-octanoyl-dopamine (NOD) activates TRPV1 and if it improves AKI. These properties of NOD and its intrinsic anti-inflammatory character were compared with those of dopamine (DA). TRPV1 activation and anti-inflammatory properties of NOD and DA were tested using primary cell cultures in vitro. The influence of NOD and DA on AKI was tested in a prospective, randomized, controlled animal study with 42 inbred male Lewis rats (LEW, RT1), treated intravenously with equimolar concentrations of DA or NOD one hour before the onset of warm ischemia and immediately before clamp release. NOD, but not DA, activates TRPV1 channels in isolated dorsal root ganglion neurons (DRG) that innervate several tissues including kidney. In TNFα stimulated proximal tubular epithelial cells, inhibition of NFκB and subsequent inhibition of VCAM1 expression by NOD was significantly stronger than by DA. NOD improved renal function compared to DA and saline controls. Histology revealed protective effects of NOD on tubular epithelium at day 5 and a reduced number of monocytes in renal tissue of DA and NOD treated rats. Our data demonstrate that NOD but not DA activates TRPV1 and that NOD has superior anti-inflammatory properties in vitro. Although NOD mitigates deterioration in renal function after AKI, further studies are required to assess to what extend this is causally related to TRPV1 activation and/or desensitization.

Role of transient receptor potential vanilloid 1 in inflammation and autoimmune diseases

Transient receptor potential vanilloid 1 (TRPV1), a non-selective cation channel, is a receptor activated by high temperatures and chemical agonists such as the vanilloids and protons. Because of these properties, TRPV1 has emerged as a polymodal nocisensor of nociceptive afferent neurons. TRPV1 is thought to be a central transducer of hyperalgesia and a prime target for controlling pain pharmacologically because it is a point where many proalgesic pathways converge and it is upregulated and sensitized by inflammation and injury. However, whether TRPV1 agonists promote or inhibit inflammation remains unclear. We recently demonstrated that SA13353 (1-[2-(1-adamantyl)ethyl]-1-pentyl-3-[3-(4-pyridyl)propyl]urea), a novel TRPV1 agonist, inhibits tumor necrosis factor-a production by the activation of capsaicin-sensitive afferent neurons and reduces the severity of symptoms in kidney injury, lung inflammation, arthritis, and encephalomyelitis. These results suggest that TRPV1 agonists may act as anti-inflammatories in certain inflammatory and autoimmune conditions in vivo. Given the potential deleterious effects of inhibiting the population of channels with a protective function, caution should be taken in the use of potent TRPV1 antagonists as a general strategy to treat inflammation. Further studies are required to clarify the role of TRPV1 and neuropeptides, which are released because of TRPV1 activation in inflammation and autoimmune diseases.

TRPV1 deletion enhances local inflammation and accelerates the onset of systemic inflammatory response syndrome

The transient receptor potential vanilloid 1 (TRPV1) is primarily localized to sensory nerve fibers and is associated with the stimulation of pain and inflammation. TRPV1 knockout (TRPV1KO) mice show enhanced LPS-induced sepsis compared with wild type (WT). This implies that TRPV1 may have a key modulatory role in increasing the beneficial and reducing the harmful components in sepsis. We investigated immune and inflammatory mechanisms in a cecal ligation and puncture (CLP) model of sepsis over 24 h. CLP TRPV1KO mice exhibited significant hypothermia, hypotension, and organ dysfunction compared with CLP WT mice. Analysis of the inflammatory responses at the site of initial infection (peritoneal cavity) revealed that CLP TRPV1KO mice exhibited: 1) decreased mononuclear cell integrity associated with apoptosis, 2) decreased macrophage tachykinin NK(1)-dependent phagocytosis, 3) substantially decreased levels of nitrite (indicative of NO) and reactive oxygen species, 4) increased cytokine levels, and 5) decreased bacteria clearance when compared with CLP WT mice. Therefore, TRPV1 deletion is associated with impaired macrophage-associated defense mechanisms. Thus, TRPV1 acts to protect against the damaging impact of sepsis and may influence the transition from local to a systemic inflammatory state.

Modulation of lipopolysaccharide-induced oxidative stress by capsaicin

This study investigated the effect of capsaicin (the active principle of hot red pepper and a sensory excitotoxin) on oxidative stress after systemic administration of the endotoxin lipopolysaccharide (100 μg/kg, i.p.) in rats. Capsaicin (15, 150 or 1,500 μg/kg; 10, 100 or 400 μg/mL) was given via intragastric (i.g.) or intraperitoneal (i.p.) routes at time of endotoxin administration. Rats were killed 4 h later. Malondialdehyde (MDA) and reduced glutathione (GSH) were measured in brain, liver, and lungs. Alanine aminotransferase (ALT), aspartate aminotransferase, alkaline phosphatase (ALP), nitric oxide, and glucose were measured in serum. In addition, histopathological examination of liver tissue was performed. In LPS-treated rats, hepatic GSH increased significantly by 40.8% after i.p. capsaicin at 1,500 μg/kg. Liver MDA increased significantly by 32.9% after the administration of i.g. capsaicin at 1,500 μg/kg and by 27.8 and 37.6% after the administration of i.p. capsaicin at 150 and 1,500 μg/kg, respectively. In lung tissue, both MDA and GSH were decreased by capsaicin administration. MDA decreased by 19-20.8% after i.g. capsaicin and by 17.5-23.2% after i.p. capsaicin (150-1,500 μg/kg), respectively. GSH decreased by 39.3-64.3% and by 35.7-41.1% after i.g. or i.p. capsaicin (150-1,500 μg/kg), respectively. Brain GSH increased significantly after the highest dose of i.g. or i.p. capsaicin (by 20.6 and 15.9%, respectively). The increase in serum ALT and ALP after endotoxin administration was decreased by oral or i.p. capsaicin. Serum nitric oxide showed marked increase after LPS injection, but was markedly decreased after capsaicin (1,500 μg/kg, i.p.). Serum glucose increased markedly after the administration of LPS, and was normalized by capsaicin treatment. It is suggested that in the presence of mild systemic inflammation, acute capsaicin administration might alter oxidative status in some tissues and exert an anti-inflammatory effect. Capsaicin exerted protective effects in the liver and lung against the LPS-induced tissue damage.

Role of the transient receptor potential vanilloid 1 in inflammation and sepsis

The transient receptor potential vanilloid 1 (TRPV1) is a thermoreceptor that responds to noxious temperatures, as well as to chemical agonists, such as vanilloids and protons. In addition, its channel activity is notably potentiated by proinflammatory mediators released upon tissue damage. The TRPV1 contribution to sensory neuron sensitization by proalgesic agents has signaled this receptor as a prime target for analgesic and anti-inflammatory drug intervention. However, TRPV1 antagonists have notably failed in clinical and preclinical studies because of their unwanted side effects. Recent reports have unveiled previously unrecognized anti-inflammatory and protective functions of TRPV1 in several diseases. For instance, this channel has been suggested to play an anti-inflammatory role in sepsis. Therefore, the use of potent TRPV1 antagonists as a general strategy to treat inflammation must be cautiously considered, given the deleterious effects that may arise from inhibiting the population of channels that have a protective function. The use of TRPV1 antagonists may be limited to treating those pathologies where enhanced receptor activity contributes to the inflamed state. Alternatively, therapeutic paradigms, such as reduction of inflammatory-mediated increase of receptor expression in the cell surface, may be a better strategy to prevent abrogation of the TRPV1 subpopulation involved in anti-inflammatory and protective processes.

Capsaicin prevents kainic acid-induced epileptogenesis in mice

Epilepsy is a neurodegenerative disease with periodic occurrences of spontaneous seizures as the main symptom. The aim of this study was to investigate the neuroprotective effects of capsaicin, the major ingredient of hot peppers, in a kainic acid (KA)-induced status epilepticus model. After intraperitoneal injections of KA (30mg/kg) in 8-week-old male ICR mice, the animals were treated subcutaneously with capsaicin (0.33mg/kg or 1mg/kg) and then examined for any anti-ictogenic, hypothermic, antioxidative, anti-inflammatory, and anti-apoptotic effects of the capsaicin treatment 3 days after KA treatment. KA injections significantly enhanced neurodegenerative conditions but co-injection with capsaicin reduced the detrimental effects of KA in a dose-dependent manner in mice. The co-administered group that received KA and 1mg/kg of capsaicin showed significantly decreased behavioral seizure activity and body temperature for 3h and also remarkably blocked intense and high-frequency seizure discharges in the parietal cortex for 3 days compared with those that received KA alone. Capsaicin treatment significantly diminished the levels of oxidant activity and malondialdehyde concentration and increased the antioxidant activity in the blood and brain of KA-treated mice. In addition, capsaicin significantly lowered the KA-induced increase in the concentration of the cytokines IL-1β and TNF-α in the brain. Furthermore, co-treatment of KA and capsaicin (1mg/kg) resulted in considerably decreased apoptotic cell death in the cornu ammonis sections of the hippocampus compared with that seen in the KA-alone group. These findings indicate that capsaicin is preventative for the epileptogenesis induced by KA in mice.

Transient receptor potential vanilloid 1 agonists as candidates for anti-inflammatory and immunomodulatory agents

We recently demonstrated that SA13353 [1-[2-(1-adamantyl)ethyl]-1-pentyl-3-[3-(4-pyridyl)propyl]urea], a novel transient receptor potential vanilloid 1 (TRPV1) agonist, inhibits TNF-alpha production through the activation of capsaicin-sensitive afferent neurons. In the present study, we investigated the effects of SA13353 on lipopolysaccharide (LPS)-induced cytokine production and a murine model of experimental autoimmune encephalomyelitis (EAE). SA13353 inhibited LPS-induced TNF-alpha and interleukin (IL)-1beta production while augmenting IL-10 production in mice. It also inhibited TNF-alpha and IL-1beta mRNA expression, and increased IL-10 mRNA expression in LPS-treated murine liver. These effects were not observed in TRPV1 KO and sensory denervated mice. Capsaicin and SA13353 increased serum neuropeptide levels, and calcitonin gene-related peptide fragment 8-37 (CGRP(8)(-)(37)), a CGRP antagonist, partially blocked the inhibitory effects of capsaicin and SA13353 on LPS-induced TNF-alpha production. These results suggest that the TPPV1 agonistic effects inhibit TNF-alpha production, at least partially, via neuropeptide release. SA13353 did not directly affect LPS-induced cytokine production in vitro using RAW264.7 macrophages, which do not express TRPV1. Therefore, we consider SA13353 to be a good tool for the investigation of the value of TRPV1 agonists for the treatment of chronic inflammation. In a murine EAE model, SA13353 attenuated clinical signs and histopathological changes. SA13353 attenuated cytokine levels, including TNF-alpha, IL-1beta, IL-12p40, IL-17, and interferon (IFN)-gamma, after proteolipid protein (PLP) immunization. In addition, SA13353 attenuated the increase of IL-17-producing cells. These results suggest that TRPV1 agonists may act as anti-inflammatory and immunomodulatory agents in vivo in certain inflammatory diseases.

Apolipoprotein A-I mimetic peptide treatment inhibits inflammatory responses and improves survival in septic rats

Systemic inflammation induces a multiple organ dysfunction syndrome that contributes to morbidity and mortality in septic patients. Since increasing plasma apolipoprotein A-I (apoA-I) and HDL may reduce the complications of sepsis, we tested the hypothesis that the apoA-I mimetic peptide 4F confers similar protective effects in rats undergoing cecal ligation and puncture (CLP) injury. Male Sprague-Dawley rats were randomized to undergo CLP or sham surgery. IL-6 levels were significantly elevated in plasma by 6 h after CLP surgery compared with shams. In subsequent studies, CLP rats were further subdivided to receive vehicle or 4F (10 mg/kg) by intraperitoneal injection, 6 h after sepsis induction. Sham-operated rats received saline. Echocardiographic studies showed a reduction in left ventricular end-diastolic volume, stroke volume, and cardiac output (CO) 24 h after CLP surgery. These changes were associated with reduced blood volume and left ventricular filling pressure. 4F treatment improved blood volume status, increased CO, and reduced plasma IL-6 in CLP rats. Total cholesterol (TC) and HDL were 79 +/- 5 and 61 +/- 4 mg/dl, respectively, in sham rats. TC was significantly reduced in CLP rats (54 +/- 3 mg/dl) due to a reduction in HDL (26 +/- 3 mg/dl). 4F administration to CLP rats attenuated the reduction in TC (69 +/- 4 mg/dl) and HDL (41 +/- 3 mg/dl) and prevented sepsis-induced changes in HDL protein composition. Increased plasma HDL in 4F-treated CLP rats was associated with an improvement in CO and reduced mortality. It is proposed that protective effects of 4F are related to its ability to prevent the sepsis-induced reduction in plasma HDL.

The transient receptor potential vanilloid 1 (TRPV1) receptor protects against the onset of sepsis after endotoxin

Transient potential vanilloid 1 (TRPV1) receptor is an ion channel receptor primarily localized on sensory nerves and activated by specific stimuli to initiate and amplify pain and inflammation, as typified by murine models of scald and arthritis. Little is known of the role of TRPV1 in sepsis, an infective disease associated with inflammation. Through use of a sublethal murine model of lipopolysaccharide-induced peritoneal sepsis, we provide novel evidence that genetic deletion of TRPV1 leads to an enhanced onset of various pathological components of systemic endotoxemia. Paired studies of TRPV1 knockout (KO) and wild-type mice demonstrate significantly enhanced hypotension (56+/-2% vs. 38+/-6% decrease in blood pressure, n=12), hypothermia (13+/-3% vs. 7+/-1% decrease in core temperature, n=6), and peritoneal exudate mediator levels (TNF-alpha, 0.78+/-0.2 vs. 0.38+/-0.1 ng/ml; nitrite, for NO, 35+/-10 vs. 15+/-3 microM; n=8) in TRPV1 KO mice, indicating loss of protective effect. Findings correlated with liver edema and raised plasma levels of aspartate aminotransferase in TRPV1 KO mice. These data suggest that TRPV1 may play an important regulatory role in sepsis independent of the major sensory neuropeptide substance P. The findings are relevant to developing strategies that increase the beneficial, and reduce the harmful, components of sepsis to prevent and treat this often fatal condition.

Effects of ketamine on levels of cytokines, NF-kappaB and TLRs in rat intestine during CLP-induced sepsis

This study was designed to investigate the effects of ketamine on levels of inflammatory cytokines, nuclear factor-kappa B (NF-kappaB) and Toll-like receptors (TLRs) in rat intestine during polymicrobial sepsis, induced by cecal ligation and puncture (CLP). After the induction of sepsis or sham-operation, the rats were treated with ketamine (2.5, 5 or 10 mg/kg) or saline (10 ml/kg). At 2, 4 or 6 h post-operation, the intestinal concentrations of inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha) and interleukin (IL)-6, were determined by enzyme-linked immunosorbent assay (ELISA). Activity of NF-kappaB in rat intestine was assessed by electrophoretic mobility shift assay (EMSA). And expressions of Toll-like receptor 2 (TLR2) and Toll-like receptor 4 (TLR4) of rat intestine were examined by reverse transcription-polymerase chain reaction (RT-PCR). We found that TNF-alpha and IL-6 concentrations, NF-kappaB activity, TLR2 and TLR4 expressions in rat intestine were increased after CLP. At the doses of 5 and 10 mg/kg, ketamine suppressed CLP-induced elevation of IL-6. Ketamine 2.5, 5 and 10 mg/kg after CLP decreased intestinal TNF-alpha level and NF-kappaB activity, and inhibited TLR2 and TLR4 expressions as well. These results suggest that ketamine may have anti-inflammatory effects, such as suppressing the levels of inflammatory cytokines and attenuating NF-kappaB activity, during polymicrobial sepsis. And these anti-inflammatory effects possibly correlate with the inhibitory influence of ketamine on TLR2 and TLR4 expressions.

Biomarker and drug-target discovery using proteomics in a new rat model of sepsis-induced acute renal failure

Sepsis is one of the common causes of acute renal failure (ARF). The objective of this study was to identify new biomarkers and therapeutic targets. We present a new rat model of sepsis-induced ARF based on cecal ligation and puncture (CLP). We used this model to find urinary proteins which may be potential biomarkers and/or drug targets. Aged rats were treated with fluids and antibiotics after CLP. Urinary proteins from septic rats without ARF and urinary proteins from septic rats with ARF were compared by difference in-gel electrophoresis (DIGE). CLP surgery elevated interleukin (IL)-6 and IL-10 serum cytokines and blood nitrite compared with sham-operated rats. However, there was a range of serum creatinine values at 24 h (0.4-2.3 mg/dl) and only 24% developed ARF. Histology confirmed renal injury in these rats. Forty-nine percent of rats did not develop ARF. Rats without ARF also had less liver injury. The mortality rate at 24 h was 27% but was increased by housing the post-surgery rats in metabolic cages. Creatinine clearance and urine output 2-8 h after CLP was significantly reduced in rats which died within 24 h. Using DIGE we identified changes in a number of urinary proteins including albumin, brush-border enzymes (e.g., meprin-1-alpha) and serine protease inhibitors. The meprin-1-alpha inhibitor actinonin prevented ARF in aged mice. In summary, we describe a new rat model of sepsis-induced ARF which has a heterogeneous response similar to humans. This model allowed us to use DIGE to find changes in urinary proteins and this approach identified a potential biomarker and drug target - meprin-1-alpha.