Modulation of mast cell proteinase-activated receptor expression and IL-4 release by IL-12

Anaphylaxis induced by Thalassophryne nattereri venom in mice is an IgE/IgG1-mediated, IL-4-dependent phenomenon

We hypothesized that beyond the Thalassophryne nattereri venoms ability to induce in mice a strong specific-Th2 response with high levels of specific IgE/IgG1, it would be able to trigger anaphylaxis in sensitized individuals. To investigate whether the venom is capable of inducing an allergic reaction in mice and characterize soluble and cellular mediators involved in this process, BALB/c female mice were sensitized intraperitoneally with decreasing-dose of venom at weekly intervals for 4 weeks and challenged by intraperitoneal, oral or epicutaneous routes with venom 2 weeks later. Our data show that sensitized-mice challenged by all routes showed intense symptoms of anaphylaxis, dependent on the anaphylactic IgG1 and IgE antibodies and mast cells. The late-phase reaction developed after initial symptoms was characterized by the influx of eosinophils, dependent on IL-5, IL-17A and eotaxin produced by Th2 cells in inflamed lungs and skin draining lymph-nodes. Using C57BL/6 deficient mice we demonstrated that IL-4 KO mice failed to develop anaphylactic symptoms or local Th2 inflammation, producing low levels of IgG1 and increased levels of IgG2a. Together our results demonstrated that the venom of T. nattereri has allergenic proteins that can trigger an allergic process, a phenomenon IgE-IgG1 dependent, IL-4-mediated and negatively regulated by IFN-γ.

An Inflammation-Centric View of Neurological Disease: Beyond the Neuron

Inflammation is a complex biological response fundamental to how the body deals with injury and infection to eliminate the initial cause of cell injury and effect repair. Unlike a normally beneficial acute inflammatory response, chronic inflammation can lead to tissue damage and ultimately its destruction, and often results from an inappropriate immune response. Inflammation in the nervous system (“neuroinflammation”), especially when prolonged, can be particularly injurious. While inflammation per se may not cause disease, it contributes importantly to disease pathogenesis across both the peripheral (neuropathic pain, fibromyalgia) and central [e.g., Alzheimer disease, Parkinson disease, multiple sclerosis, motor neuron disease, ischemia and traumatic brain injury, depression, and autism spectrum disorder] nervous systems. The existence of extensive lines of communication between the nervous system and immune system represents a fundamental principle underlying neuroinflammation. Immune cell-derived inflammatory molecules are critical for regulation of host responses to inflammation. Although these mediators can originate from various non-neuronal cells, important sources in the above neuropathologies appear to be microglia and mast cells, together with astrocytes and possibly also oligodendrocytes. Understanding neuroinflammation also requires an appreciation that non-neuronal cell—cell interactions, between both glia and mast cells and glia themselves, are an integral part of the inflammation process. Within this context the mast cell occupies a key niche in orchestrating the inflammatory process, from initiation to prolongation. This review will describe the current state of knowledge concerning the biology of neuroinflammation, emphasizing mast cell-glia and glia-glia interactions, then conclude with a consideration of how a cell's endogenous mechanisms might be leveraged to provide a therapeutic strategy to target neuroinflammation.

Mast cells are critical for the limitation of thrombin-induced skin inflammation

Thrombin, a key player in coagulation, is widely held to induce and promote inflammation. As of now, the features, kinetics and control of thrombin's proinflammatory effects on the skin remain to be characterized in detail. We, therefore, injected thrombin into the ear skin of mice and observed strong, dose-dependent and transient ear swelling responses as well as mast cell (MC) degranulation. Unexpectedly, thrombin induced even stronger, not reduced, ear swelling in MC-deficient Kit^W-sh/W-sh mice. Prior local reconstitution of Kit^W-sh/W-sh mice with MCs inhibited this effect, indicating that MCs may contribute to the control of thrombin-induced skin inflammation. In line with previous studies, we found that MCs express the thrombin receptors PAR1, PAR3 and PAR4, thrombin induces direct and dose-dependent MC degranulation, and that degranulated MCs inactivate thrombin. Further findings suggested that MC-mediated protection from thrombin-induced inflammation is likely to rely on the effects of MC proteases. We show for the first time that MC-deficient mice and MC protease 4-deficient mice with normal numbers of MCs show markedly increased ear swelling in response to thrombin as compared to wild-type mice. Taken together, these results suggest that thrombin-induced skin inflammation is controlled, in part, by MC protease 4 released from activated MCs. For MC-driven diseases such as chronic spontaneous urticaria, which has been linked to increased thrombin generation, this might mean that MCs may contribute to the resolution of skin inflammatory responses.

Enhanced Expression of IL-18 and IL-18BP in Plasma of Patients with Eczema: Altered Expression of IL-18BP and IL-18 Receptor on Mast Cells

IL-18 has been found to be associated with eczema. However, little is known of the role of IL-18 binding protein (BP) and IL-18 receptor (R) in eczema. We therefore investigated the expression of IL-18, IL-18BP, and IL-18R on mast cells by using flow cytometry analysis and mouse eczema model. The results showed that plasma free IL-18 and free IL-18BP levels in eczema patients were higher than those in healthy controls. IL-18 provoked up to 3.1-fold increase in skin mast cells. IL-18 induced also an increase in IL-18BP+ mast cells, but a reduction of IL-18R+ mast cells in mouse eczema skin. It was found that house dust mite allergen Der p1 and egg allergen OVA induced upregulation of the expression of IL-18, IL-18BP, and IL-18R mRNAs in HMC-1 cells following 2 and 16 h incubation. In conclusion, correlation of IL-18 and IL-18BP in eczema plasma suggests an important balance between IL-18 and IL-18BP in eczema. The decrease in molar concentration ratio of plasma IL-18BP/IL-18 and allergen-induced upregulated expression of IL-18 and IL-18R in skin mast cells of the patients with eczema suggests that anti-IL-18 including IL-18BP therapy may be useful for the treatment of eczema.

Upregulated expression of CCR3 in rheumatoid arthritis and CCR3-dependent activation of fibroblast-like synoviocytes

It is recognized that CC chemokine receptor 3 (CCR3) is associated with numerous inflammatory conditions and fibroblast-like synoviocyte (FLS) invasiveness correlates with articular damage in rheumatoid arthritis (RA). However, little is known of the expression and action of CCR3 on FLS in RA. In the present study, we investigated the expression of CCR3 on dispersed synovial tissue and peripheral blood cells in RA and influence of eotaxin-1 on FLS functions by using flow cytometry analysis, FLS challenge, and real-time PCR techniques. The results showed that approximately 7.0 % dispersed synovial cells are CCR3+ cells. Among those CCR3+ cells, 38.1, 23.8, and 20.6 % cells are CD90+CD14-CD3- (representing FLS), CD14+, and CD8+ cells, respectively, indicating that FLS is one of the major populations of CCR3+ cells in the synovial tissue of RA. In peripheral blood, CD14+ CCR3+ cells are elevated, but CD8+CCR3+ cells are reduced in RA. It was found that eotaxin-1 induced upregulated expression of CCR3 and matrix metalloproteinase (MMP)-9 messenger RNAs (mRNAs) in FLS. Since an antagonist of CCR3 suppressed the action of eotaxin-1, the event appeared CCR3 dependent. Moreover, we observed that interleukin (IL)-1β induced markedly enhanced eotaxin-1 release from FLS, but TNF-α reduced eotaxin-1 release at 12 and 24 h following incubation. In conclusion, enhanced expression of CCR3 on synovial cells and increased levels of eotaxin-1 in plasma and synovial fluid (SF) of RA indicate that CCR3-mediated mechanisms may play an important role in RA. Blockage of eotaxin-1 provoked CCR3 and MMP-9 expression in FLS by antagonist of CCR3, implicating that anti-CCR3 agents may have therapeutic use for RA.

Upregulated expression of CCR3 in osteoarthritis and CCR3 mediated activation of fibroblast-like synoviocytes

OBJECTIVES

Upregulated expression of CC chemokine receptor (CCR)3 was observed in osteoarthritis (OA) cartilage and chondrocytes, but expression of CCR3 on synovial tissue of OA remains unknown. Fibroblast-like synoviocyte (FLS) invasion in synovium appears one of the features of OA, but expression and function of CCR3 on FLS remain uninvestigated. We therefore explored them in the present study.

METHODS

Enzymatically dispersed synovial tissue cells were analyzed by flowcytometry. Primary cultured FLS isolated from OA synovium were challenged and the expression of CCR3, eotaxin-1 and matrix metalloproteinase (MMP)-9 was determined by quantitative real-time PCR (qPCR) and ELISA.

RESULTS

Approximately 4.5% dispersed OA synovial tissue cells are CCR3+ cells. Among them, 58.4% cells are CD90+CD14-CD3- cells (representing FLS) and 36.7% are CD8+ cells, indicating that FLS are major population of CCR3+ cells in the synovial tissue. Levels of eotaxin-1 and MMP-9 in OA synovial fluid (SF) were greater than that in OA plasma and in healthy control (HC) plasma. Eotaxin-1 induced up to 5.8 and 7.2-fold increases in the expression of MMP-9 mRNA and protein, respectively following 12h incubation with FLS, which was inhibited by antagonist of CCR3 SB328437 and an inhibitor of ERK U0126, indicating that action of eotaxin-1 on FLS seemed via CCR3 and ERK signaling pathway. IL-1β and TNF-α was found to elicit release of eotaxin-1 from OA FLS.

CONCLUSION

FLS via eotaxin-1 and its receptor CCR3 plays an important role in the pathogenesis of OA, which strengthen the concept that OA is likely an inflammation related disease.

Mast cells, glia and neuroinflammation: partners in crime?

Glia and microglia in particular elaborate pro-inflammatory molecules that play key roles in central nervous system (CNS) disorders from neuropathic pain and epilepsy to neurodegenerative diseases. Microglia respond also to pro-inflammatory signals released from other non-neuronal cells, mainly those of immune origin such as mast cells. The latter are found in most tissues, are CNS resident, and traverse the blood-spinal cord and blood-brain barriers when barrier compromise results from CNS pathology. Growing evidence of mast cell-glia communication opens new perspectives for the development of therapies targeting neuroinflammation by differentially modulating activation of non-neuronal cells that normally control neuronal sensitization - both peripherally and centrally. Mast cells and glia possess endogenous homeostatic mechanisms/molecules that can be up-regulated as a result of tissue damage or stimulation of inflammatory responses. Such molecules include the N-acylethanolamine family. One such member, N-palmitoylethanolamine is proposed to have a key role in maintenance of cellular homeostasis in the face of external stressors provoking, for example, inflammation. N-Palmitoylethanolamine has proven efficacious in mast-cell-mediated experimental models of acute and neurogenic inflammation. This review will provide an overview of recent progress relating to the pathobiology of neuroinflammation, the role of microglia, neuroimmune interactions involving mast cells and the possibility that mast cell-microglia cross-talk contributes to the exacerbation of acute symptoms of chronic neurodegenerative disease and accelerates disease progression, as well as promoting pain transmission pathways. We will conclude by considering the therapeutic potential of treating systemic inflammation or blockade of signalling pathways from the periphery to the brain in such settings.

Evaluation on potential contributions of protease activated receptors related mediators in allergic inflammation

Protease activated receptors (PARs) have been recognized as a distinctive four-member family of seven transmembrane G protein-coupled receptors (GPCRs) that can be cleaved by certain serine proteases. In recent years, there has been considerable interest in the role of PARs in allergic inflammation, the fundamental pathologic changes of allergy, but the potential roles of PARs in allergy remain obscure. Since many of these proteases are produced and actively involved in the pathologic process of inflammation including exudation of plasma components, inflammatory cell infiltration, and tissue damage and repair, PARs appear to make important contribution to allergy. The aim of the present review is to summarize the expression of PARs in inflammatory and structural cells, the influence of agonists or antagonists of PARs on cell behavior, and the involvement of PARs in allergic disorders, which will help us to better understand the roles of serine proteases and PARs in allergy.

Generation of mast cells from mouse fetus: analysis of differentiation and functionality, and transcriptome profiling using next generation sequencer

While gene knockout technology can reveal the roles of proteins in cellular functions, including in mast cells, fetal death due to gene manipulation frequently interrupts experimental analysis. We generated mast cells from mouse fetal liver (FLMC), and compared the fundamental functions of FLMC with those of bone marrow-derived mouse mast cells (BMMC). Under electron microscopy, numerous small and electron-dense granules were observed in FLMC. In FLMC, the expression levels of a subunit of the FcεRI receptor and degranulation by IgE cross-linking were comparable with BMMC. By flow cytometry we observed surface expression of c-Kit prior to that of FcεRI on FLMC, although on BMMC the expression of c-Kit came after FcεRI. The surface expression levels of Sca-1 and c-Kit, a marker of putative mast cell precursors, were slightly different between bone marrow cells and fetal liver cells, suggesting that differentiation stage or cell type are not necessarily equivalent between both lineages. Moreover, this indicates that phenotypically similar mast cells may not have undergone an identical process of differentiation. By comprehensive analysis using the next generation sequencer, the same frequency of gene expression was observed for 98.6% of all transcripts in both cell types. These results indicate that FLMC could represent a new and useful tool for exploring mast cell differentiation, and may help to elucidate the roles of individual proteins in the function of mast cells where gene manipulation can induce embryonic lethality in the mid to late stages of pregnancy.

Modulation of PAR expression and tryptic enzyme induced IL-4 production in mast cells by IL-29

Interleukin (IL)-29 is a relatively newly discovered cytokine, which has been shown to be actively involved in the pathogenesis of allergic inflammation. However, little is known of the effects of IL-29 on protease activated receptor (PAR) expression and potential mechanisms of cytokine production in mast cells. In the present study, we examined potential influence of IL-29 on PAR expression and cytokine production in P815 and bone marrow derived mast cells (BMMCs) by using flow cytometry analysis, quantitative real time PCR, and ELISA techniques. The results showed that IL-29 downregulated the expression of PAR-1 by up to 56.2%, but had little influence on the expression of PAR-2, PAR-3 and PAR-4. IL-29 also induced downregulation of expression of PAR-1 mRNA. However, when mast cells were pre-incubated with IL-29, thrombin-, trypsin- and tryptase-induced expression of PAR-2, PAR-3 and PAR-4 was upregulated, respectively. IL-29 provoked approximately up to 1.9-fold increase in IL-4 release when mast cells was challenged with IL-29. Administration of IL-29 blocking antibody, AG490 or LY294002 abolished IL-29-induced IL-4 release from P815 cells. It was found that IL-29 diminished trypsin- and tryptase-induced IL-4 release from P815 cells following 16 h incubation. In conclusion, IL-29 can regulate expression of PARs and tryptase- and trypsin-induced IL-4 production in mast cells, through which participates in the mast cell related inflammation.

Neuroprotective effect of protease-activated receptor-2 in the hypoxia-induced apoptosis of rat RGC-5 cells

Hypoxia-induced apoptosis of retinal ganglion cells (RGCs) is regarded as a pivotal pathological process in various ocular diseases. Protease-activated receptor-2 (PAR-2) is involved in the regulation of cell inflammation, differentiation, and apoptosis in many cell types and tissues, but the role of PAR-2 in RGCs under pathological conditions remains unknown. The purpose of this study was to investigate the role of PAR-2 in the apoptosis of RGCs under hypoxic stress. An immortalized rat RGC line (RGC-5) was exposed to hypoxia (5 % O₂). The expression and location of PAR-2 in RGC-5 cells under hypoxia stress were investigated using real-time PCR, western blotting and immunocytochemistry. Cell viability was determined using the Cell Counting Kit-8 assay. Apoptosis was detected using Hoechst 33342 staining and AnnexinV-FITC/PI assays. The role of Bcl-2, Bax, and the active subunit of caspase-3 was also investigated. The results showed that PAR-2 was functionally expressed in RGC-5 cells and up-regulated at both mRNA and protein levels under hypoxic stress. The PAR-2 selective agonist, SLIGRL, rescued RGC-5 cells from hypoxia-induced apoptosis through up-regulation of the Bcl-2/Bax ratio and down-regulation of caspase-3 activation. This study provides the first evidence that PAR-2 has a protective effect against the hypoxia-induced apoptosis of RGC-5 cells.

Early control of Mycobacterium tuberculosis infection requires il12rb1 expression by rag1-dependent lineages

IL12RB1 is essential for human resistance to Mycobacterium tuberculosis infection. In the absence of a functional IL12RB1 allele, individuals exhibit susceptibility to disseminated, recurrent mycobacterial infections that are associated with defects in both RAG1-dependent and RAG1-independent hematopoietic lineages. Despite this well-established association, a causal relationship between M. tuberculosis susceptibility and IL12RB1 deficiency in either RAG1-dependent or RAG1-independent lineages has never been formally tested. Here, we use the low-dose aerosol model of experimental tuberculosis (TB) to both establish that infected il12rb1(-/-) mice recapitulate important aspects of TB in IL12RB1 null individuals and, more importantly, use radiation bone marrow chimeras to demonstrate that restriction of il12rb1 deficiency solely to rag1-dependent lineages (i.e., T and B cells) allows for the full transfer of the il12rb1(-/-) phenotype. We further demonstrate that the protection afforded by adaptive lymphocyte il12rb1 expression is mediated partially through ifng and that, within the same infection, il12rb1-sufficient T cells exhibit dominance over il12rb1-deficient T cells by enhancing ifng expression in the latter population. Collectively, our data establish a basic framework in which to understand how IL12RB1 promotes control of this significant human disease.

Expression and release of IL-29 by mast cells and modulation of mast cell behavior by IL-29

BACKGROUND

The role of interleukin (IL)-29 in innate immunity has been recognized recently, and it is regarded as a potent bioactive molecule. However, little is known about its role in the pathogenesis of allergy. Because mast cells are recognized as primary effector cells of allergy, we investigated the potential relationship between IL-29 and mast cells in this study.

OBJECTIVE

To examine the expression of IL-29 in mast cells and the influence of IL-29 on mast cell mediator release and accumulation.

METHODS

Expression of IL-29 in mast cells was determined by double-labeling immunohistochemistry and flow cytometry analysis. Mast cell cell-line was cultured to examine the mediator release, and mouse peritoneal model was employed to observe the mast cell accumulation.

RESULTS

Large proportions of mast cells expressing IL-29 were localized in human tissue including the colon, tonsil and lung. Mast cells can release substantial quantity of IL-29 upon challenge with proteolytic allergens. Extrinsic IL-29 provoked IL-4 and IL-13 release from mast cell line P815 cells through PI3K/Akt and (JAK)/STAT3 signaling pathways, but failed to induce mast cell histamine release from human mast cells. Extrinsic IL-29 also induced mast cell infiltration in mouse peritoneum by a CD18- and ICAM1-dependent mechanism.

CONCLUSION

Mast cell-derived IL-29 has the potential to be involved in the pathogenesis of allergic inflammation.

Induction of IL-13 production and upregulation of gene expression of protease activated receptors in P815 cells by IL-6

Interleukin (IL)-6 is a multifunctional cytokine which has been showed to induce up-regulated expression of Fc epsilon RI receptor and histamine production in mast cells. However, little is known of its effects on Th2 cytokine secretion and protease activated receptor (PAR) expression in mast cells. In the present study, we examined potential influence of IL-6 on IL-13, IL-4 and IL-10 release from P815 cells and PAR expression on P815 cells by using flow cytometry analysis, quantitative real-time PCR, ELISA and cellular activation of signaling ELISA (CASE) techniques. The results showed that IL-6 induced up to 1.8-fold increase in IL-13, but not IL-4 or IL-10 release from P815 cells, and FSLLRY-NH(2) did not affect IL-6 induced IL-13 release. Tryptase elicited 2.0-fold increase in IL-13 release from P815 cells, which can be inhibited by IL-6. IL-6 elicited the up-regulated expression of PAR-1, PAR-2, PAR-3 and PAR-4 mRNAs, but had little effects on expression of PAR proteins. U0126, PD98059 and LY204002 abolished IL-6 induced IL-13 release when they were preincubated with P815 cells, indicating ERK and Akt cell signaling pathways may be involved in the event. In conclusion, IL-6 can stimulate IL-13 release from mast cells through an ERK and Akt cell signaling pathway dependent, but PAR independent mechanism.

Downregulation of protease activated receptor expression and cytokine production in P815 cells by RNA interference

BACKGROUND

Protease-activated receptors (PAR) are seven transmembrane G-coupled receptors comprising four genes (PAR-1 approximately PAR-4). Mast cell has been identified to be able to express PARs and release an array of cytokines upon activation. Recently, it was reported that interleukin (IL)-12 could regulate the expression of PARs in mast cells, and tryptase could induce IL-4 and IL-6 release from mast cells. In order to further investigate the issues, RNA interference (RNAi) technique was employed and small interfering RNAs (siRNA) of PARs were transfected in P815 cells.

RESULTS

The results showed that siRNAs for PAR-1, PAR-2 and PAR-4 significantly downregulated expression of PAR-1, PAR-2 and PAR-4 mRNAs and proteins in P815 cells at 24, 48 and 72 h following transfection. siRNA PAR-1.2 and siRNA PAR-4.2 significantly reduced IL-12 induced upregulation of PAR-1 and PAR-4 expression, respectively when P815 cells were transfected with them for 48 h. siRNA PAR-2.3 blocked IL-12 induced downregulation of PAR-2 expression on both mRNA and protein levels. It was also observed that siRNA PAR-2.3 and siRNA PAR-1.2 reduced trypsin induced IL-4 release by approximately 92.6% and 65.3%, and SLIGKV-NH2 induced IL-4 release by 82.1% and 60.1%, respectively. Similarly, siRNA PAR-2.3 eliminated tryptase-induced IL-4 release by 75.3%, and siRNA PAR-1.2 diminished SFLLR-NH2 induced IL-4 release by 79.3%. However, siRNA PAR-1.2, siRNA PAR-2.3 and siRNA PAR-4.3 at 10 nM did not show any effect on tryptase-induced IL-6 release from P815 cells.

CONCLUSION

In conclusion, siRNAs of PARs can modulate PAR expression and PAR related cytokine production in mast cells, confirming that PARs are likely to play a role in allergic reactions.

Induction of IL-4 release and upregulated expression of protease activated receptors by GM-CSF in P815 cells

GM-CSF has been showed to be able to induce up-regulated receptor and cytokine expression in mast cells in inflammatory conditions. However, little is known of its effects on protease activated receptor (PAR) expression and Th2 cytokine secretion from mast cells. In the present study, we examined potential influence of GM-CSF on mast cell PAR expression and IL-4 and IL-10 release by using flow cytometry analysis, quantitative real time PCR, ELISA and cellular activation of signaling ELISA (CASE) techniques. The results showed that GM-CSF induced up to 3.0-fold increase in IL-4 release from P815 cells, and FSLLRY-NH(2) and trans-cinnamoyl (tc)-YPGKF-NH(2) did not affect GM-CSF induced IL-4 release. GM-CSF reduced tryptase and trypsin induced IL-4 release by up to approximately 55.8% and 70.3%, respectively. GM-CSF elicited the upregulated expression of PAR-1, PAR-2, PAR-3 and PAR-4 mRNAs, but enhanced only PAR-4 protein expression in P815 cells. U0126, PD98059 and LY204002 almost completely abolished GM-CSF induced IL-4 release when they were preincubated with P815 cells for 30 min, indicating ERK and Akt cell signaling pathways may be involved in the event. In conclusion, GM-CSF can stimulate IL-4 release from mast cells through an ERK and Akt cell signaling pathway dependent, but PAR independent mechanism. GM-CSF may serve as a regulator for IL-4 production in mast cells and through which participates in the mast cell related inflammation.

Upregulation of Toll-like receptor (TLR) expression and release of cytokines from P815 mast cells by GM-CSF

Backgroud

Recently, mast cells have been recognized to express several Toll-like receptors (TLRs) on their membrane surfaces, and granulocyte-macrophage colony-stimulating factor (GM-CSF) was reported to be able to alter expression of TLRs and cytokine production in neutrophils. However, whether GM-CSF modulates the expression of TLR and cytokine production in mast cells is not clear.

Results

Using flow cytometry and real time PCR techniques, we found that GM-CSF upregulated expression of TLR3 and TLR7 in P815 cells in a concentration dependent manner. GM-CSF also provoked approximately up to 2.4 and 2.3 fold increase in IL-13 and IL-6 release from P815 cells, respectively following 16 h incubation. GM-CSF induced IL-13 secretion, TLR3 and TLR7 expression appeared to be through activation of mitogen-activated protein kinase (MAPK) and phosphotidylinositol 3-kinase (PI3K)/Akt signaling pathways, whereas GM-CSF elicited IL-6 release seemed via Akt signaling pathway. At 10 ng/ml, GM-CSF significantly enhanced R-848-induced IL-6 release from P815 cells.

Conclusion

The ability of GM-CSF in modulation of expression of TLR3 and TLR7 in P815 mast cells and in stimulation of IL-13 and IL-6 release from P815 mast cells in vitro suggests that GM-CSF might play an important role in enhancing the innate immune responses of mast cell to viral infection

Transcription factor network downstream of protease activated receptors (PARs) modulating mouse bladder inflammation

BACKGROUND

All four PARs are present in the urinary bladder, and their expression is altered during inflammation. In order to search for therapeutic targets other than the receptors themselves, we set forth to determine TFs downstream of PAR activation in the C57BL/6 urinary bladders.

METHODS

For this purpose, we used a protein/DNA combo array containing 345 different TF consensus sequences. Next, the TF selected was validated by EMSA and IHC. As mast cells seem to play a fundamental role in bladder inflammation, we determined whether c-kit receptor deficient (Kit w/Kit w-v) mice have an abrogated response to PAR stimulation. Finally, TFEB antibody was used for CHIP/Q-PCR assay and revealed up-regulation of genes known to be downstream of TFEB.

RESULTS

TFEB, a member of the MiTF family of basic helix-loop-helix leucine zipper, was the only TF commonly up-regulated by all PAR-APs. IHC results confirm a correlation between inflammation and TFEB expression in C57BL/6 mice. In contrast, Kit w/Kit w-v mice did not exhibit inflammation in response to PAR activation. EMSA results confirmed the increased TFEB binding activity in C57BL/6 but not in Kit w/Kit w-v mice.

CONCLUSION

This is the first report describing the increased expression of TFEB in bladder inflammation in response to PAR activation. As TFEB belongs to a family of TFs essential for mast cell survival, our findings suggest that this molecule may influence the participation of mast cells in PAR-mediated inflammation and that targeting TFEB/MiTF activity may be a novel approach for the treatment of bladder inflammatory disorders.