TRPV1 mediates capsaicin-stimulated metabolic activity but not cell death or inhibition of interleukin-1β release in human THP-1 monocytes

Human monocytes and dendritic cells express transient receptor potential vanilloid 1 (TRPV1) which may play a role in mediating the inflammatory, immune and cancer surveillance responses of these cells. The aim of the present study was to investigate TRPV1 expression and function in THP-1 monocytic cells. RT-PCR and Western blot were used to detect TRPV1. The metabolic activity and viability of THP-1 cells following exposure to vanilloids was assessed using resorufin production from rezazurin. Cytokine release was measured using ELISA. TRPV1 was expressed in cultured THP-1 monocytic cells and naïve monocytes. Lower concentrations (<250 μM) of capsaicin, but not other putative TRPV1 agonists, were shown to stimulate cell metabolic activity, whereas at concentrations >250 μM, all agonists decreased metabolic activity. Capsaicin-stimulated THP-1 metabolic activity was blocked by the TRPV1 antagonist, 5-iodo-resiniferatoxin (5'-IRTX), whereas the decline in resorufin production by THP-1 cells at higher capsaicin concentrations (due to cell death), was not affected by 5'-IRTX. Finally, capsaicin (≤125 μM) significantly increased lipopolysaccharide-stimulated IL-6 and TNF-α release from THP-1 cells, whereas phytohaemagglutinin-stimulated IL-1β, TNF-α, MCP-1 and IL-6 release were concentration-dependently inhibited by capsaicin. Modulation of IL-1β release was not TRPV1 mediated. Overall, these results show that functional TRPV1 channels are present in naïve monocytes and THP-1 cells, and when activated, increase cell metabolic activity. In addition, capsaicin modifies cytokine release from THP-1 cells and induces cell death, most likely by a mechanism that is independent of TRPV1 activation.

ERBB3: A potential serum biomarker for early detection and therapeutic target for devil facial tumour 1 (DFT1)

Devil Facial Tumour 1 (DFT1) is one of two transmissible neoplasms of Tasmanian devils (Sarcophilus harrisii) predominantly affecting their facial regions. DFT1's cellular origin is that of Schwann cell lineage where lesions are evident macroscopically late in the disease. Conversely, the pre-clinical timeframe from cellular transmission to appearance of DFT1 remains uncertain demonstrating the importance of an effective pre-clinical biomarker. We show that ERBB3, a marker expressed normally by the developing neural crest and Schwann cells, is immunohistohemically expressed by DFT1, therefore the potential of ERBB3 as a biomarker was explored. Under the hypothesis that serum ERBB3 levels may increase as DFT1 invades local and distant tissues our pilot study determined serum ERBB3 levels in normal Tasmanian devils and Tasmanian devils with DFT1. Compared to the baseline serum ERBB3 levels in unaffected Tasmanian devils, Tasmanian devils with DFT1 showed significant elevation of serum ERBB3 levels. Interestingly Tasmanian devils with cutaneous lymphoma (CL) also showed elevation of serum ERBB3 levels when compared to the baseline serum levels of Tasmanian devils without DFT1. Thus, elevated serum ERBB3 levels in otherwise healthy looking devils could predict possible DFT1 or CL in captive or wild devil populations and would have implications on the management, welfare and survival of Tasmanian devils. ERBB3 is also a therapeutic target and therefore the potential exists to consider modes of administration that may eradicate DFT1 from the wild.

Bitter melon protects against ER stress in LS174T colonic epithelial cells

BACKGROUND

Bitter Melon (BM) has been used as a functional food in traditional Chinese and Indian medicine for many generations and has gained a great deal of attention due to its apparent benefits in moderating some of the pathogenic processes in a variety of inflammatory conditions. BM extract (BME) has been shown to possess strong anti-oxidant properties. In addition, it can ameliorate oxidative stress and potentially ER stress. There is increasing evidence that oxidative and ER stress are major contributors for intestinal secretory cell dysfunction which leads to local inflammation and disease pathogenesis that are hallmarks of inflammatory bowel diseases (IBD). Hence, the search for potential therapeutics against ER stress and oxidative stress in intestinal epithelial secretory cells may provide valuable resources for the management of IBD. The aim of the present study was to investigate the effects of BME in ameliorating ER stress in colonic epithelial cells.

METHODS

Human colonic adenocarcinoma LS174T cells were used for the assessment of BME effects on colonic epithelial cells in vitro. Cell viability was assessed using trypan blue exclusion and the effect of BME in ameliorating tunicamycin (TM)-induced ER stress was determined by analysing the mRNA expression of the common ER stress markers; ATF6, XBP1, GRP78, CHOP and PERK by quantitative RT-PCR and GRP78 and CHOP by western blot.

RESULTS

In the absence of ER stress, BME exhibited no cell toxicity up to 2.0% w/v and no significant effect on the basal mRNA expression of ER stress markers in LS174T cells. In contrast, pre-treatment of LS174T cells with BME followed by induction of ER stress resulted in a significant decrease in mRNA expression of ATF6, XBP1, GRP78, CHOP and PERK and protein expression of GRP78 and CHOP. Co-treatment during induction of ER stress and post- treatment following induction of ER Stress in LS174T cells resulted in a lower but still significant reduction in mRNA expression levels of most ER stress markers.

CONCLUSIONS

This is one of the first studies demonstrating the efficacy of BME in reducing expression of ER stress markers in colonic epithelial cells suggesting the potential of BME as a dietary intervention in ameliorating ER stress and oxidation in IBD. Interestingly, while the most significant effect was seen with pre-treatment of cells with BME there was a reduced but still significant effect when co-treated or even post-treated. This suggests that BME may even be effective in modulating ER stress in the face of an existing cell stress environment.

Effect of epithelial cell type on in vitro invasion of non-typeable Haemophilus influenzae

Non-typeable Haemophilus influenzae (NTHi) have been shown to have variable ability for in vitro invasion with a range of epithelial cells, and increased invasion of BEAS-2B cells has been associated with altered penicillin binding protein3 (PBP3), which is concerning as these strains are increasing worldwide. The aim of the study was to investigate the effect of respiratory cell type and the presence of altered PBP3 on the in vitro invasion of NTHi. A collection of 16 clinical NTHi isolates was established, 7 had normal PBP3, and 9 had altered PBP3 as defined by an N526K substitution. The isolates were tested for invasion of BEAS-2B, NHBE, A549 and NCI-H292 respiratory epithelial cells in vitro using a gentamicin survival assay, with invasion measured as the percentage of intracellular organisms relative to the initial inoculum. The overall median invasion for the 16 NTHi isolates for cell types BEAS-2B, NHBE, A549 and NCI-H292 cells were 3.17, 2.31, 0.11 and 1.52 respectively. The differences were statistically significant for BEAS-2B compared to A549 (P=0.015) and A549 compared to NCI-H292 (P=0.015), and there were also very marked differences in invasion for some individual isolates depending on the cell type used. There was a consistent bias for invasion of isolates with normal versus abnormal PBP3: and this was statistically significant for BEAS-2B (0.07 to 9.90, P=0.031) and A549 cells (0.02 to 1.68, P=0.037). These results show that NTHi invasion of respiratory epithelial cells in vitro is both strain dependant and influenced significantly by the cell line used, and that the association between altered PBP3 and increased invasion is conserved across multiple cell lines.

Capsaicin-Induced Death of Human Haematological Malignant Cell Lines Is Independent of TRPV1 Activation

The effect of the plant-derived vanilloid, capsaicin (CAP), on the metabolic activity of THP-1, U266B1 and U937 hematological malignancy cells was determined. CAP reduced metabolic activity in a concentration-dependent manner in the three cell lines. A biphasic effect was observed on THP-1 cells (EC50: IC50 (95% CI) 32.9 (19.9-54.3)/219 (144-246) µmol/l). U266B1 cells were more resistant to CAP than THP-1 and U937. Metabolic activity was significantly inhibited by CAP in U937 compared to U266B1 cells (IC50: 197 versus 431 µmol/l, respectively, p < 0.008). Transient receptor potential vanilloid-1 (TRPV1) and CB1 antagonists (SB452533 and AM251, respectively) suppressed the CAP-induced increase in THP-1 cell metabolic activity (p < 0.001). AM251 and SB452533 appeared to act as partial agonists and displayed a synergistic effect with CAP in U937 cells. CAP inhibits the metabolic activity of malignant hematological cells through non-TRPV1-dependent mechanisms.

Genotypically defined β-lactamase-negative ampicillin-resistant isolates of non-typable Haemophilus influenzae are associated with increased invasion of bronchial epithelial cells in vitro

The aim of the study was to investigate the association between the presence of altered penicillin-binding protein 3 (PBP3) in non-typable Haemophilus influenzae (NTHi) and an increased capacity to invade bronchial epithelial cells in vitro. A collection of 40 clinical isolates of NTHi comprised of 20 with normal PBP3 and 20 with altered PBP3 (defined by an N526K substitution) was established. The isolates were tested for the ability to invade bronchial epithelial cells in vitro using a 4 h gentamicin survival assay. Invasion was measured as the percentage of intracellular organisms relative to the initial inoculum. The mean invasion rate was 0.00-14.79 % in the normal PBP3 isolates and 0.02-36.69 % in the altered PBP3 isolates. The altered PBP3 isolates had a higher (P = 0.003) mean invasion rate (6.86 %, n = 20) than the normal PBP3 isolates (1.31 %, n = 20). Subsequently, two variants of altered PBP3 (transformant 1, N526K; transformant 2, M377I, S385T, L389F and N526K) were cloned into three of the initial isolates (parents) with normal PBP3 and relatively low invasive ability, and the parents and transformants tested for invasion as above. There was no difference (P = 0.89) in the mean invasion rates for the parents (0.81 %, n = 3), transformants 1 (0.90 %, n = 3) and transformants 2 (1.38 %, n = 3). There was an association between the presence of altered PBP3 in NTHi and an increased capacity to invade BEAS-2B cells in vitro, but cloning experiments suggested that the altered PBP3 was not involved directly in enhanced invasion.

Tachykinin (NK1, NK2 and NK3) receptor, transient receptor potential vanilloid 1 (TRPV1) and early transcription factor, cFOS, mRNA expression in rat tissues following systemic capsaicin treatment

Capsaicin, the pungent component of chilli pepper, stimulates TRPV1-expressing cells which are followed by desensitisation to subsequent exposure to capsaicin and other TRPV1 activators. At high systemic doses (>125 mg/kg), capsaicin produces long-term changes in both tachykinin receptor and TRPV1 expression and function in rats. However, whether desensitising (low) doses of capsaicin (~50 mg/kg) affect tachykinin receptor and TRPV1 gene expression in the short term has yet to be investigated. The aim of the present study was to compare tachykinin receptor (NK1, NK2 and NK3) and TRPV1 mRNA expression 24h after administration of capsaicin (50 mg/kgs.c.). Tachykinin receptor and TRPV1 mRNA were detected in all tissues studied with expression levels differing by up to 2500-fold between tissues. The highest expression of TRPV1 and NK1 mRNA was observed in the salivary gland, whereas NK2 mRNA expression was highest in the urinary bladder and NK3 mRNA expression in the frontal cortex. In the cervical spinal cord of rats treated with capsaicin, NK1 and NK3 mRNA expression were reduced by 56% and 80%, respectively (P<0.05), whereas NK2 and TRPV1 mRNA expression were increased 2.2- and 1.4-fold, respectively (P<0.05). NK1 and NK2 mRNA expression were decreased (P<0.05) in the urinary bladder and gastric fundus, respectively, following capsaicin treatment. There was a marked 100-fold increase in cFOS mRNA expression and 100-fold decrease in NK2 mRNA expression in the whole blood of capsaicin-treated rats. In conclusion, these studies show that tachykinin receptor and TRPV1 mRNA expression undergo significant changes within 24h of systemic low-dose capsaicin administration.

Relationships between single nucleotide polymorphisms of antioxidant enzymes and disease

The presence and progression of numerous diseases have been linked to deficiencies in antioxidant systems. The relationships between single nucleotide polymorphisms (SNPs) arising from specific antioxidant enzymes and diseases associated with elevated oxidative stress have been studied with the rationale that they may be useful in screening for diseases. The purpose of this narrative review is to analyse evidence from these studies. The antioxidant enzyme SNPs selected for analysis are based on those most frequently investigated in relation to diseases in humans: superoxide dismutase (SOD2) Ala16Val (80 studies), glutathione peroxidise (GPx1) Pro197Leu (24 studies) and catalase C-262T (22 studies). Although the majority of evidence supports associations between the SOD2 Ala16Val SNP and diseases such as breast, prostate and lung cancers, diabetes and cardiovascular disease, the presence of the SOD2 Ala16Val SNP confers only a small, clinically insignificant reduction (if any) in the risk of these diseases. Other diseases such as bladder cancer, liver disease, nervous system pathologies and asthma have not been consistently related to this SOD SNP genotype. The GPx1 Pro197Leu and catalase C-262T SNP genotypes have been associated with breast cancer, but only in a small number of studies. Thus, currently available evidence suggests antioxidant enzyme SNP genotypes are not useful for screening for diseases in humans.

Effects of systemic capsaicin treatment on TRPV1 and Tachykinin NK(1) receptor distribution and function in the nucleus of the solitary tract of the adult rat

Vanilloids including capsaicin and resiniferatoxin (RTX) have been identified as potential novel anti-inflammatory and analgesic compounds. We have previously shown that systemic capsaicin administration to neonatal rats evokes profound long-term alterations in transient receptor potential vanilloid 1 (TRPV1)- and neurokinin 1 (NK(1)) receptor-mediated respiratory responses in the commissural nucleus of the solitary tract (cNTS). Whether this effect of capsaicin is unique to developmentally immature animals is unknown. Therefore, in the present study, we investigated the effects of systemic capsaicin administration to adult rats on NK(1) receptor binding sites, TRPV1 and NK(1) immunoreactivity and function in the cNTS. Microinjection of capsaicin (1 nmol) or RTX (75 pmol) into the cNTS of vehicle-pretreated rats produced a profound bradypnoea (maximum change: -45 breaths·min(-1)) and a small increase in tidal volume (VT). Similarly, microinjection of the selective NK(1) receptor agonists [Sar(9), Met(O(2))(11)]substance P (SP; 66 pmol) and septide (20 pmol) decreased respiratory frequency and increased VT. Thirteen to 18 days after systemic administration of capsaicin (125 mg·kg(-1) s.c.), the bradypnoeic responses to both capsaicin and RTX were absent (p < 0.05), indicative of sensory neuron ablation/desensitisation. Systemic capsaicin pretreatment significantly (p < 0.05) reduced the density of both [(125)I]Bolton-Hunter SP binding sites (NK(1) receptors) and NK(1) receptor immunoreactivity in the cNTS, but did not alter the respiratory responses evoked by microinjection of [Sar(9), Met(O(2))(11)]SP and septide into this region. These studies show that systemic capsaicin administration reduces NK(1) receptor density in the cNTS without adversely affecting NK(1) receptor function at this site. We speculate that adult rats may be more resistant than neonatal rats to the neuroplastic effects of systemic capsaicin administration.

Glutathione peroxidase, superoxide dismutase and catalase genotypes and activities and the progression of chronic kidney disease

BACKGROUND

Oxidative stress has been linked to the progression of disease, including chronic kidney disease (CKD). The aim of the present study was to determine the association between single-nucleotide polymorphisms (SNPs) of the antioxidant enzymes, superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase and their activities and the progression of CKD.

METHODS

This is a prospective cohort study of 185 CKD patients (Stages 2-4), followed for up to 12 months. All patients were genotyped for SNPs of SOD (SOD Ala16Val), GPx (GPx Pro197Leu) and catalase (C-262T). The rate of change over the study period of estimated glomerular filtration rate (eGFR), plasma and red blood cell (RBC) GPx, RBC SOD and RBC catalase activities were determined.

RESULTS

CKD patients with the SOD Ala/Val and Val/Val genotypes had a significantly greater eGFR decline compared to those with the Ala/Ala genotype (Ala/Val compared with Ala/Ala odds ratio (OR) 0.35, 95% CI 0.19 to 0.64, P = 0.001; Val/Val compared with Ala/Ala OR 0.25, 95% CI 0.10 to 0.65, P = 0.005). The progression of CKD was not associated with SNPs of the GPx or catalase genes studied but there was a direct relationship between the rate of change of plasma GPx activity and the rate of change of eGFR over 12 months (P = 0.025).

CONCLUSION

CKD patients with the SOD Ala/Val and Val/Val genotypes have a greater decline in kidney function than those with the Ala/Ala genotype.

TRPV1, NK1 receptor and substance P immunoreactivity and gene expression in the rat lumbosacral spinal cord and urinary bladder after systemic, low dose vanilloid administration

Transient receptor potential vanilloid 1 (TRPV1), neurokinin 1 (NK1) receptor and substance P (SP) immunoreactivity (-ir) and mRNA in the rat lumbosacral spinal cord and urinary bladder were measured 24h after s.c. injection of the vanilloids, capsaicin (50mg/kg) and resiniferatoxin (RTX, 100μg/kg), or vehicle (10% ethanol/10% Tween 80/saline). In the spinal cord, capsaicin significantly reduced TRPV1 and SP-ir (40-45%) in laminae I/II compared to controls, while RTX produced decreases of ~35%. NK1-ir in the spinal cord was unaffected by both vanilloid treatments. In the bladder, SP-ir was reduced in urothelial cells of some capsaicin- and RTX-treated rats, while SP-ir in the suburothelium and muscularis was significantly reduced by RTX. A significant increase in NK1-ir was observed in the urothelium and muscularis after capsaicin administration. Capsaicin significantly increased SP mRNA in the spinal cord, and TRPV1 and SP mRNA in the bladder, whereas RTX increased TRPV1, SP and NK1 mRNA in the spinal cord, and TRPV1 and SP mRNA in the bladder. These data suggest that stimulation of TRPV1 by low dose vanilloid administration can rapidly (within 24h) alter both transcription and translation of TRPV1 channels, SP and NK1 receptors in the rat urinary bladder and spinal cord.

Effects of capsaicin, dihydrocapsaicin, and curcumin on copper-induced oxidation of human serum lipids

The oxidation of low-density lipoprotein (LDL) is believed to be the initiating factor for the development and progression of atherosclerosis. The active ingredients of spices such as chili and turmeric (capsaicin and curcumin, respectively) have been shown to reduce the susceptibility of LDL to oxidation. One of the techniques used to study the oxidation of LDL is to isolate LDL and subject it to metal-induced (copper or iron) oxidation. However, whole serum may represent a closer situation to in vivo conditions than using isolated LDL. We investigated the effects of different concentrations (0.1-3 microM) of capsaicin, dihydrocapsaicin, and curcumin on copper-induced oxidation of serum lipoproteins. The lag time (before initiation of oxidation) and rate of oxidation (slope of propagation phase) were calculated. The lag time increased, and the rate of oxidation decreased with increasing concentrations of the tested antioxidants (p < 0.05). A 50% increase in lag time (from control) was observed at concentrations between 0.5 and 0.7 microM for capsaicin, dihydrocapsaicin, and curcumin. This study shows that oxidation of serum lipids is reduced by capsaicinoids and curcumin in a concentration-dependent manner.

Expression of transient receptor potential vanilloid 1 (TRPV1) and 2 (TRPV2) in human peripheral blood

The vanilloid receptor family of cation channels includes the capsaicin-sensitive, proton- and heat-activated TRPV1 and noxious heat-activated TRPV2. The present study demonstrates both gene and protein expression of TRPV1 and TRPV2 in human peripheral blood cells (PBCs) using molecular and immunocytochemical techniques. Using reverse-transcription polymerase chain reaction (RT-PCR) and quantitative real-time RT-PCR (qRT-PCR), TRPV1 and TRPV2 mRNA was detected in mRNA isolated from human whole peripheral blood. Using qRT-PCR, TRPV2 mRNA was highly expressed in human whole blood isolates (9.33+/-1.19 x 10(4)copies per 10(6)copies of the housekeeping gene GAPDH), whereas TRPV1 message was detected at approximately 150-fold lower levels (638+/-121 copies per 10(6)copies GAPDH). At the protein level, TRPV1 and TRPV2 activity was determined immunocytochemically in a lymphocyte-enriched mononuclear cell preparation (83+/-2% lymphocytes). Cells were labelled with rabbit anti-TRPV1 or goat anti-TRPV2 (1:500) and subsequently labelled with goat Texas red- (TRPV1) or FITC-(TRPV2) conjugated secondary antibodies (1:1000). All cells demonstrated punctate TRPV1-immunoreactivity, which appeared to be on the plasma membrane and in the cytoplasm. In contrast, cells within subjects appeared to express the TRPV1 protein at varying intensities. TRPV2-immunoreactivity appeared diffuse. This is the first study to demonstrate the presence of both TRPV1 and TRPV2 in human peripheral lymphocytes. Further studies need to be undertaken in order to determine the role of TRPV channels in these cells.