Capsaicin induces the production of IL-6 in human upper respiratory epithelial cells

Thermosensitive TRP Channels Are Functionally Expressed and Influence the Lipogenesis in Human Meibomian Gland Cells

While the involvement of thermosensitive transient receptor potential channels (TRPs) in dry eye disease (DED) has been known for years, their expression in the meibomian gland (MG) has never been investigated. This study aims to show their expression and involvement in the lipogenesis of the MG, providing a possible new drug target in the treatment of DED. Our RT-PCR, Western blot and immunofluorescence analysis showed the expression of TRPV1, TRPV3, TRPV4 and TRPM8 in the MG at the gene and the protein level. RT-PCR also showed gene expression of TRPV2 but not TRPA1. Calcium imaging and planar patch-clamping performed on an immortalized human meibomian gland epithelial cell line (hMGECs) demonstrated increasing whole-cell currents after the application of capsaicin (TRPV1) or icilin (TRPM8). Decreasing whole-cell currents could be registered after the application of AMG9810 (TRPV1) or AMTB (TRPM8). Oil red O staining on hMGECs showed an increase in lipid expression after TRPV1 activation and a decrease after TRPM8 activation. We conclude that thermo-TRPs are expressed at the gene and the protein level in MGs. Moreover, TRPV1 and TRPM8's functional expression and their contribution to their lipid expression could be demonstrated. Therefore, TRPs are potential drug targets and their clinical relevance in the therapy of meibomian gland dysfunction requires further investigation.

[WITHDRAWN] Neuron-dependent tuft cell expansion initiates sinonasal allergic Type 2 inflammation

The authors have withdrawn this manuscript owing to inaccuracies in the calculation of tuft cell numbers and errors in the selection of immunofluorescence images used to support our claims. Therefore, the authors do not wish this work to be cited as reference for the project. If you have any questions, please contact the corresponding author.

Capsaicin and Its Effect on Exercise Performance, Fatigue and Inflammation after Exercise

Capsaicin (CAP) activates the transient receptor potential vanilloid 1 (TRPV1) channel on sensory neurons, improving ATP production, vascular function, fatigue resistance, and thus exercise performance. However, the underlying mechanisms of CAP-induced ergogenic effects and fatigue-resistance, remain elusive. To evaluate the potential anti-fatigue effects of CAP, 10 young healthy males performed constant-load cycling exercise time to exhaustion (TTE) trials (85% maximal work rate) after ingestion of placebo (PL; fiber) or CAP capsules in a blinded, counterbalanced, crossover design, while cardiorespiratory responses were monitored. Fatigue was assessed with the interpolated twitch technique, pre-post exercise, during isometric maximal voluntary contractions (MVC). No significant differences (p > 0.05) were detected in cardiorespiratory responses and self-reported fatigue (RPE scale) during the time trial or in TTE (375 ± 26 and 327 ± 36 s, respectively). CAP attenuated the reduction in potentiated twitch (PL: -52 ± 6 vs. CAP: -42 ± 11%, p = 0.037), and tended to attenuate the decline in maximal relaxation rate (PL: -47 ± 33 vs. CAP: -29 ± 68%, p = 0.057), but not maximal rate of force development, MVC, or voluntary muscle activation. Thus, CAP might attenuate neuromuscular fatigue through alterations in afferent signaling or neuromuscular relaxation kinetics, perhaps mediated via the sarco-endoplasmic reticulum Ca2+ ATPase (SERCA) pumps, thereby increasing the rate of Ca2+ reuptake and relaxation.

Comparative effects of capsaicin in chronic obstructive pulmonary disease and asthma (Review)

Chronic obstructive pulmonary disease (COPD) and asthma are chronic respiratory diseases with high prevalence and mortality that significantly alter the quality of life in affected patients. While the cellular and molecular mechanisms engaged in the development and evolution of these two conditions are different, COPD and asthma share a wide array of symptoms and clinical signs that may impede differential diagnosis. However, the distinct signaling pathways regulating cough and airway hyperresponsiveness employ the interaction of different cells, molecules, and receptors. Transient receptor potential cation channel subfamily V member 1 (TRPV1) plays a major role in cough and airway inflammation. Consequently, its agonist, capsaicin, is of substantial interest in exploring the cellular effects and regulatory pathways that mediate these respiratory conditions. Increasingly more studies emphasize the use of capsaicin for the inhalation cough challenge, yet the involvement of TRPV1 in cough, bronchoconstriction, and the initiation of inflammation has not been entirely revealed. This review outlines a comparative perspective on the effects of capsaicin and its receptor in the pathophysiology of COPD and asthma, underlying the complex entanglement of molecular signals that bridge the alteration of cellular function with the multitude of clinical effects.

Loading of capsaicin-in-cyclodextrin inclusion complexes into PEGylated liposomes and the inhibitory effect on IL-8 production by MDA-MB-231 and A549 cancer cell lines

Capsaicin (CAP) is an active component in Capsicum annuum L. known to have anti inflammatory and anticancer activity. CAP is highly lipophilic and suffers low bioavailability. Therefore, developing delivery systems that enhance solubility and bioavailability can provide more promising therapeutic applications for CAP. In the current work, CAP was complexed with β-cyclodextrin (βCD) to form capsaicin-in-β-cyclodextrin (CAP-in-βCD) inclusion complexes. Then, the CAP-in-βCD inclusion complexes were characterized and loaded into PEGylated liposomes using the thin-film hydration extrusion method. The size, charge, and polydispersity index (PDI) of the PEGylated liposomes were characterized. The levels of IL-8 production were quantified after treatment using array beads. The results of this work showed that the successful formation of inclusion complexes at 1:5 M ratio of CAP to βCD respectively. PEGylated liposomes loaded with βCD/CAP inclusion complexes (CAP-in-βCD-in-liposomes) have a hydrodynamic diameter of (181 ± 36) nm, zeta potential of (-2.63 ± 4.00) mV, encapsulation efficiency (EE) of (38.65 ± 3.70)%, drug loading (DL) of (1.65 ± 0.16)%, and a stable release profile. Both free CAP and liposomal CAP showed a significant reduction in the IL-8 production by the MDA-MB-231 and A549 cancer cell lines after treatment. In conclusion, a liposomal-based drug delivery system for CAP was achieved.

A TRiP Through the Roles of Transient Receptor Potential Cation Channels in Type 2 Upper Airway Inflammation

PURPOSE OF REVIEW

Despite their high prevalence, the pathophysiology of allergic rhinitis (AR) and chronic rhinosinusitis (CRS) remains unclear. Recently, transient receptor potential (TRP) cation channels emerged as important players in type 2 upper airway inflammatory disorders. In this review, we aim to discuss known and yet to be explored roles of TRP channels in the pathophysiology of AR and CRS with nasal polyps.

RECENT FINDINGS

TRP channels participate in a plethora of cellular functions and are expressed on T cells, mast cells, respiratory epithelial cells, and sensory neurons of the upper airways. In chronic upper airway inflammation, TRP vanilloid 1 is mostly studied in relation to nasal hyperreactivity. Several other TRP channels such as TRP vanilloid 4, TRP ankyrin 1, TRP melastatin channels, and TRP canonical channels also have important functions, rendering them potential targets for therapy. The role of TRP channels in type 2 inflammatory upper airway diseases is steadily being uncovered and increasingly recognized. Modulation of TRP channels may offer therapeutic perspectives.

Transient receptor potential vanilloid 1 promotes EGFR ubiquitination and modulates EGFR/MAPK signalling in pancreatic cancer cells

Transient receptor potential vanilloid-1 (TRPV1) was first identified in sensory neurons, where it was suggested as a therapeutic target for pain relief. Here, we show that TRPV1 is expressed in the pancreatic cancer cell line, PANC-1; that epidermal growth factor receptor (EGFR) expression is downregulated by overexpression or agonist-induced activation of TRPV1; and conversely, that EGFR expression is increased after silencing TRPV1. Furthermore, TRPV1 overexpression inhibits cell proliferation and significantly reduces the mRNA levels of two oncogenes, KRAS and AKT2. More importantly, TRPV1 downregulates EGFR levels by inducing EGFR ubiquitination and degradation, which modulate EGFR/MAPK signalling in pancreatic cancer cells. These results illustrate the regulation and mechanism of TRPV1 on EGFR in pancreatic cancer cells and may provide new ideas for the design of novel antitumor drugs targeting EGFR. SIGNIFICANCE OF THE STUDY: We investigated the effect and mechanism of TRPV1 on EGFR-mediated proliferation and transformation of pancreatic cancer cells, with the aim of providing new ideas and experimental evidence for the application of strategies that promote EGFR degradation to treat pancreatic cancer.

High and low temperatures aggravate airway inflammation of asthma: Evidence in a mouse model

Epidemiology suggests ambient temperature is the triggers and potential activator of asthma. The role of high and low temperatures on airway inflammation of asthma, and the underlying molecular mechanism are not yet understood. A mouse model of asthma was adopted in our experiment. The BALB/c mice were exposed at different temperature for 4 h (2 h in the morning and 2 h in the afternoon) on weekday. The exposure temperatures were 10 °C, 24 °C and 40 °C. Ovalbumin (OVA) was used to sensitize the mice on days 14, 18, 22, 26, and 30, followed by an aerosol challenge for 30 min from day 32-38. After the final OVA challenge, lung function, serum protein and pulmonary inflammation were assessed. Comparing the OVA with the saline group at 24 °C, we saw a significant increase in: serum Total-IgE (p < 0.05); OVA-sIgE (p < 0.01); IL-4 (p < 0.05); IL-1β (p < 0.01); IL-6 (p < 0.01); TNF-α (p < 0.01); and the ratio of IL-4/IFN-γ (p < 0.01). At the same time, there was a significant decrease in IFN-γ (p < 0.01). As the temperature increase, there is a U shape for immune proteins and pro-inflammatory factors with a peak value at 24 °C, exception for IFN-γ (inverted U-shape). After the high and low temperature exposure, the Ri and Re increased significantly, while Cldyn decreased significantly compared with the 24 °C group. Histopathological analysis of the OVA groups showed airway remodeling, airway wall thickening and deforming, and subepithelial fibrosis. More obvious changes were found in the high and low temperature exposure groups. The immunohistochemistry suggested that TRPs changed with temperatures. High and low temperatures can aggravate airway inflammation in a mouse model of asthma. TRPs play an important role in temperature aggravation of allergic asthma. The results suggest that asthmatics should avoid exposure to high and low temperatures for too long time.

The emerging role of transient receptor potential channels in chronic lung disease

Chronic lung diseases such as asthma, chronic obstructive pulmonary disease and idiopathic pulmonary fibrosis are a major and increasing global health burden with a high unmet need. Drug discovery efforts in this area have been largely disappointing and so new therapeutic targets are needed. Transient receptor potential ion channels are emerging as possible therapeutic targets, given their widespread expression in the lung, their role in the modulation of inflammatory and structural changes and in the production of respiratory symptoms, such as bronchospasm and cough, seen in chronic lung disease.

The role of TRPV1 in the CD4+ T cell-mediated inflammatory response of allergic rhinitis

Transient receptor potential vanilloid 1 (TRPV1), which has been identified as a molecular target for the activation of sensory neurons by various painful stimuli, was reported to regulate the signaling and activation of CD4⁺ T cells. However, the role of TRPV1 in CD4⁺ T cell in allergic rhinitis remains poorly understood. In this study, TRPV1 expression was localized in CD4⁺ T cells. Both knockout and chemical inhibition of TRPV1 suppressed Th2/Th17 cytokine production in CD4 T cells and Jurkat T cells, respectively, and can suppress T cell receptor signaling pathways including NF-κB, MAP kinase, and NFAT. In TRPV1 knockout allergic rhinitis (AR) mice, eosinophil infiltration, Th2/Th17 cytokines in the nasal mucosa, and total and ova-specific IgE levels in serum decreased, compared with wild-type AR mice. The TRPV1 antagonists, BCTC or theobromine, showed similar inhibitory immunologic effects on AR mice models. In addition, the number of TRPV1⁺/CD4⁺ inflammatory cells increased in the nasal mucosa of patients with AR, compared with that of control subjects. Thus, TRPV1 activation on CD4⁺ T cells is involved in T cell receptor signaling, and it could be a novel therapeutic target in AR.

Mustard vesicant-induced lung injury: Advances in therapy

Most mortality and morbidity following exposure to vesicants such as sulfur mustard is due to pulmonary toxicity. Acute injury is characterized by epithelial detachment and necrosis in the pharynx, trachea and bronchioles, while long-term consequences include fibrosis and, in some instances, cancer. Current therapies to treat mustard poisoning are primarily palliative and do not target underlying pathophysiologic mechanisms. New knowledge about vesicant-induced pulmonary disease pathogenesis has led to the identification of potentially efficacious strategies to reduce injury by targeting inflammatory cells and mediators including reactive oxygen and nitrogen species, proteases and proinflammatory/cytotoxic cytokines. Therapeutics under investigation include corticosteroids, N-acetyl cysteine, which has both mucolytic and antioxidant properties, inducible nitric oxide synthase inhibitors, liposomes containing superoxide dismutase, catalase, and/or tocopherols, protease inhibitors, and cytokine antagonists such as anti-tumor necrosis factor (TNF)-α antibody and pentoxifylline. Antifibrotic and fibrinolytic treatments may also prove beneficial in ameliorating airway obstruction and lung remodeling. More speculative approaches include inhibitors of transient receptor potential channels, which regulate pulmonary epithelial cell membrane permeability, non-coding RNAs and mesenchymal stem cells. As mustards represent high priority chemical threat agents, identification of effective therapeutics for mitigating toxicity is highly significant.

Azelastine desensitization of transient receptor potential vanilloid 1: a potential mechanism explaining its therapeutic effect in nonallergic rhinitis

BACKGROUND

Capsaicin, a prototypic transient receptor potential vanilloid 1 (TRPV1) agonist, has been shown to be more clinically effective in the treatment of nonallergic rhinitis (NAR) compared with other rhinitis subtypes. Azelastine has also been found to be clinically effective in the treatment of NAR but its mechanism(s) of action is still poorly elucidated. This study was designed to determine, using in vitro cell lines, whether topical therapies including azelastine have activity on TRPV1 ion channels similar to capsaicin.

METHODS

The effects of capsaicin (1 μM), azelastine (30 μM), bepotastine (10 μM), olopatadine (10 μM), and fluticasone (200 μM) on TRPV1 channels using mice neuronal cells (Cath.a), as surrogates for submucosal sensory neurons, and human nasal epithelial cells (hNEC) were determined and compared. For azelastine, bepotastine, and capsaicin, which elicited an agonist effect on TRPV1, live cell [Ca(2+)] signaling in Cath.a cells and hNECs expressing TRPV1 were performed in the absence and presence of capsazepine at 10 μM (a TRPV1 antagonist) or using wild-type mouse embryonic fibroblasts (wtMEFs) that express TRPV1 ion channels and TRPV1 homozygous null mutant (TRPV1-/-) knockout MEF cells as controls to establish TRPV1 channel selectivity. As azelastine has previously been found clinically effective in NAR, additional experiments were performed to determine its ability to desensitize TRPV1 ion channels and its effect on regulating intracellular calcium homeostasis.

RESULTS

Cath.a cells treated with azelastine, bepotastine, or capsaicin showed a significant increase in TRPV1-dependant (Ca(2+)) specific cytosolic fluorescence. Continuous treatment with azelastine or capsaicin resulted in desensitization of TRPV1 channels. In hNECs, azelastine stimulation resulted in Ca(2+) shifts from the cytosol to mitochondria and overexpression of hematopoietic cell-specific Lyn substrate 1-associated protein X1, which may thus be effective in cytosolic Ca(2+) homeostasis.

CONCLUSION

Azelastine, similar to capsaicin, exhibits direct activity on TRPV1 ion channels that may represent a novel mechanistic pathway explaining its clinical efficacy in NAR.

Association of interleukin 6 single nucleotide polymorphisms with allergic rhinitis

OBJECTIVES

Allergic rhinitis (AR) is a polygenic inflammatory disorder of the nasal mucosa with an increasing prevalence worldwide. As interleukin 6 (IL-6) seems to be involved in development of allergic disorders, such as allergic rhinitis, this study was performed to evaluate the association of two promotor variants of IL-6 gene in the AR.

METHODS

Ninety eight patients with AR were enrolled in this study. Genotyping was done for two polymorphisms in a promoter region of IL-6 gene (G/C at -174, rs1800795 and G/A at -597, rs1800797), using a PCR sequence-specific-primers method.

RESULTS

Patients homozygous for the G allele of rs1800795 in IL-6 had a 3.35-fold risk of having AR than those with the C allele. AA genotype in rs1800797 of IL-6 was associated with the increased risk of developing AR. G/G haplotype for IL-6 (rs1800795, rs1800797) was significantly higher in the patient group. In some subgroups of patients, there were significant relationships between IgE levels, eosinophil count, eosinophil percentage, nature of sensitivity and persistency of disease and these two variants.

CONCLUSION

We found that two promotor variants in IL-6, especially rs1800795, were predisposing factors for AR with a negative heterosis pattern. These SNPs could also affect the clinical parameters, the nature of sensitivity and persistency of the disease in some subgroups of the patients.

Transient receptor potential (TRP) channels in the airway: role in airway disease

Over the last few decades, there has been an explosion of scientific publications reporting the many and varied roles of transient receptor potential (TRP) ion channels in physiological and pathological systems throughout the body. The aim of this review is to summarize the existing literature on the role of TRP channels in the lungs and discuss what is known about their function under normal and diseased conditions. The review will focus mainly on the pathogenesis and symptoms of asthma and chronic obstructive pulmonary disease and the role of four members of the TRP family: TRPA1, TRPV1, TRPV4 and TRPM8. We hope that the article will help the reader understand the role of TRP channels in the normal airway and how their function may be changed in the context of respiratory disease.

Unravelling the mystery of capsaicin: a tool to understand and treat pain

A large number of pharmacological studies have used capsaicin as a tool to activate many physiological systems, with an emphasis on pain research but also including functions such as the cardiovascular system, the respiratory system, and the urinary tract. Understanding the actions of capsaicin led to the discovery its receptor, transient receptor potential (TRP) vanilloid subfamily member 1 (TRPV1), part of the superfamily of TRP receptors, sensing external events. This receptor is found on key fine sensory afferents, and so the use of capsaicin to selectively activate pain afferents has been exploited in animal studies, human psychophysics, and imaging studies. Its effects depend on the dose and route of administration and may include sensitization, desensitization, withdrawal of afferent nerve terminals, or even overt death of afferent fibers. The ability of capsaicin to generate central hypersensitivity has been valuable in understanding the consequences and mechanisms behind enhanced central processing of pain. In addition, capsaicin has been used as a therapeutic agent when applied topically, and antagonists of the TRPV1 receptor have been developed. Overall, the numerous uses for capsaicin are clear; hence, the rationale of this review is to bring together and discuss the different types of studies that exploit these actions to shed light upon capsaicin working both as a tool to understand pain but also as a treatment for chronic pain. This review will discuss the various actions of capsaicin and how it lends itself to these different purposes.

Transient receptor potential vanilloid-1 participates in the inhibitory effect of ginsenoside Rg1 on capsaicin-induced interleukin-8 and prostaglandin E2 production in HaCaT cells

OBJECTIVES

Ginsenoside Rg1 (GRg1), one of the major active constituents of Panax notoginseng, has shown anti-inflammatory and antinocioceptic activity, but its role in keratinocytes needs further study. We have examined the inhibitory effect of GRg1 on transient receptor potential vanilloid-1 (TRPV1) activation in keratinocyte HaCaT cells and explored its involved mechanism.

METHODS

HEK 293T cells over-expressing exogenous TRPV1 were constructed and named HEK 293T-TRPV1 cells. The effects of GRg1 on production of interleukin-8 (IL-8) and prostaglandin E(2) (PGE(2) ), calcium influx, the expression of cyclooxygenase-2 (COX-2) and nuclear factor-κB (NF-κB) transcriptional activity in HEK 293T-TRPV1 and HaCaT cells were examined by ELISA, Fluo 3-AM fluorescence probe, Western blot and Dual-Luciferase Reporter Assay, respectively.

KEY FINDINGS

The results showed that GRg1 blocked intracellular calcium by both capsaicin and proton activation in a TRPV1-dependent manner. Furthermore, GRg1 inhibited the expression of COX-2 and NF-κB transcriptional activity induced by capsaicin in keratinocytes. The inhibitory effect of GRg1 was similar to capsazepine, an antagonist of TRPV1. More importantly, GRg1 dose-dependently inhibited capsaicin-induced PGE(2) and IL-8 secretion in HaCaT cells and HEK 293T-TRPV1 cells.

CONCLUSIONS

These data showed that GRg1 could inhibit TRPV1 mediated responses in HaCaT cells, indicating that GRg1 acted as a TRPV1 antagonist.

Streptozotocin-induced early thermal hyperalgesia is independent of glycemic state of rats: role of transient receptor potential vanilloid 1(TRPV1) and inflammatory mediators

Background

Streptozotocin (STZ) is used as a common tool to induce diabetes and to study diabetes-induced complications including diabetic peripheral neuropathy (DPN). Previously, we have reported that STZ induces a direct effect on neurons through expression and function of the Transient receptor potential vanilloid 1 (TRPV1) channel in sensory neurons resulting in thermal hyperalgesia, even in non-diabetic STZ-treated mice. In the present study, we investigated the role of expression and function of TRPV1 in the central sensory nerve terminals in the spinal cord in STZ-induced hyperalgesia in rats.

Results

We found that a proportion of STZ-treated rats were normoglycemic but still exhibited thermal hyperalgesia and mechanical allodynia. Immunohistochemical data show that STZ treatment, irrespective of glycemic state of the animal, caused microglial activation and increased expression of TRPV1 in spinal dorsal horn. Further, there was a significant increase in the levels of pro-inflammatory mediators (IL-1β, IL-6 and TNF-α) in spinal cord tissue, irrespective of the glycemic state. Capsaicin-stimulated release of calcitonin gene related peptide (CGRP) was significantly higher in the spinal cord of STZ-treated animals. Intrathecal administration of resiniferatoxin (RTX), a potent TRPV1 agonist, significantly attenuated STZ-induced thermal hyperalgesia, but not mechanical allodynia. RTX treatment also prevented the increase in TRPV1-mediated neuropeptide release in the spinal cord tissue.

Conclusions

From these results, it is concluded that TRPV1 is an integral component of initiating and maintaining inflammatory thermal hyperalgesia, which can be alleviated by intrathecal administration of RTX. Further, the results suggest that enhanced expression and inflammation-induced sensitization of TRPV1 at the spinal cord may play a role in central sensitization in STZ-induced neuropathy.

TRPV1 and TRPA1 stimulation induces MUC5B secretion in the human nasal airway in vivo

AIM

Nasal transient receptor potential vanilloid 1 (TRPV1) stimulation with capsaicin produces serous and mucinous secretion in the human nasal airway. The primary aim of this study was to examine topical effects of various TRP ion channel agonists on symptoms and secretion of specific mucins: mucin 5 subtype AC (MUC5AC) and B (MUC5B).

METHODS

Healthy individuals were subjected to nasal challenges with TRPV1 agonists (capsaicin, olvanil and anandamide), TRP ankyrin 1 (TRPA1) agonists (cinnamaldehyde and mustard oil) and a TRP melastatin 8 (TRPM8) agonist (menthol). Symptoms were monitored, and nasal lavages were analysed for MUC5AC and MUC5B, i.e. specific mucins associated with airway diseases. In separate groups of healthy subjects, nasal biopsies and brush samples were analysed for TRPV1 and MUC5B, using immunohistochemistry and RT-qPCR. Finally, calcium responses and ciliary beat frequency were measured on isolated ciliated epithelial cells.

RESULTS

All TRP agonists induced nasal pain or smart. Capsaicin, olvanil and mustard oil also produced rhinorrhea. Lavage fluids obtained after challenge with capsaicin and mustard oil indicated increased levels of MUC5B, whereas MUC5AC was unaffected. MUC5B and TRPV1 immunoreactivities were primarily localized to submucosal glands and peptidergic nerve fibres, respectively. Although trpv1 transcripts were detected in nasal brush samples, functional responses to capsaicin could not be induced in isolated ciliated epithelial cells.

CONCLUSION

Agonists of TRPV1 and TRPA1 induced MUC5B release in the human nasal airways in vivo. These findings may be of relevance with regard to the regulation of mucin production under physiological and pathophysiological conditions.

A New Approach to Ventilator-associated Pneumonia Based on the PIRO System

Several new scoring systems have been developed over recent years to assess the degree of organ failure (e.g., Acute Physiology and Chronic Health Evaluation [APACHE] II, APACHE III, Sequential Organ Failure Assessment [SOFA], Simplified Acute Physiology Score [SAPS] II, and Multiple Organ Dysfunction Score [MODS]). Most of these were models generated based on the concepts of sepsis, severe sepsis and septic shock. In 2001, an International Sepsis Definition Conference updated these terms in order to facilitate standardized enrolment into clinical trials, but due to their simplicity and easy use physicians rapidly adopted them for daily clinical practice [1].

Airway irritability--a burning issue?

Systems biology is being increasingly used to probe the underlying pathophysiology of asthma, although serious challenges remain to decipher the physiologic significance of the information revealed in these studies relating to gene expression and regulatory gene networks often used to understand gene-gene interactions. One phenotypic change characteristic of asthma is increased airway irritability, or bronchial hyperresponsiveness (BHR) which is still poorly understood. While the precise mechanism(s) remain(s) to be identified, a number of hypotheses have been posited to account for this phenomenon, including airways inflammation, alteration in airway smooth muscle function, and airway remodeling. However, the role of sensory nerves in this phenomenon has received scant attention yet offers a potentially new target for the development of novel drugs.

Expression of transient receptor potential vanilloid 1 (TRPV1) in synovial fibroblasts from patients with osteoarthritis and rheumatoid arthritis

The transient receptor potential vanilloid 1 (TRPV1) is a nonselective cation channel, which is mainly expressed by nociceptive neurons in dorsal root and trigeminal ganglia. However, there is increasing evidence that TRPV1 expression is not limited to primary afferent neurons but that the receptor is expressed in various cell types throughout the body. Here, we demonstrate the expression of TRPV1 in synovial fibroblasts (SF) from patients with symptomatic osteoarthritis (OA) and rheumatoid arthritis (RA). In addition, the mRNA expression of TRPV1 was shown in PBMCs from healthy controls and from OA patients. The presence of TRPV1 was confirmed at the protein level. Stimulation of cultured OA- and RA-SF with the TRPV1 agonist capsaicin led to increased expression of IL-6 mRNA as well as of IL-6 protein in the cell culture supernatants. IL-6 protein expression could be antagonized with capsazepine. Thus, we hypothesize that TRPV1 may play a role in non-neuronal mechanisms that might modulate nociception in symptomatic OA and RA patients.