COX-2 Specific Inhibitor, NS-398, Increases Macrophage Migration Inhibitory Factor Expression and Induces Neuroendocrine Differentiation in C4-2b Prostate Cancer Cells

Naoxintong restores ischemia injury and inhibits thrombosis via COX2-VEGF/ NFκB signaling

ETHNOPHARMACOLOGICAL RELEVANCE

Naoxintong (NXT) is a traditional Chinese medicine preparation that is often used in combination with aspirin in the treatment of cardiovascular diseases (CVD). One of the main symptoms of CVD is hypoxic-ischemia (HI). The purpose of this study is to find out the molecular nodes targeted by NXT and its related molecular pathways in vascular repair.

MATERIALS AND METHODS

First, human vein umbilical endothelial cells (EA.hy926) were utilized to set up the Oxygen-Glucose Deprivation-Reoxygenation (OGD/R) model and treated with NXT. Cell proliferation, damage and apoptosis were detected by MTT, LDH, and flow cytometry assays. Second, transcriptional responses of OGD/R cells to NXT treatment were investigated. qRT-PCR, western blotting and inhibitor assays were performed. Third, the anti-thrombotic effect of NXT was evaluated by the zebrafish thrombosis model. Morphological observation, histological staining and qRT-PCR assays were implemented on zebrafish model to further observe in vivo the therapeutic effects of NXT on ischemia and thrombosis.

RESULTS

In OGD/R EA.hy926 cells, NXT treatment could reduce ischemic vascular injury, increase cell viability and decrease the proportion of apoptosis. Through RNA-seq analysis, 183 differentially expressed genes (DEGs) were screened with 110 up-regulated genes and 73 down-regulated genes between OGD/R and OGD/R + NXT treated EA.hy926 cells. VEGF and NFκB pathways were enriched. Among these genes, COX2 was identified as one of important targets via which NXT could restore vascular injury. COX2 inhibitor (NS-398), and aspirin, a drug that prevents the development of CVD by targeting COX2, exhibited similar effects to NXT in the treatment of OGD/R EA.hy926 cells. In zebrafish thrombosis model, NXT could attenuate tail venous thrombus and recover the quantity of heart red blood cells. Furthermore, NXT could prevent the formulation of thrombosis and eliminate inflammation in zebrafish by COX2-VEGF/NFκB signaling.

CONCLUSION

Our studies implicated that NXT could restore HI injury and inhibit thrombosis through COX2-VEGF/NFκB signaling, which is consistent with the molecular target of aspirin. This finding might explain the principle of NXT combined with aspirin in the treatment of cardiovascular diseases.

Neuroendocrine Differentiation of Prostate Cancer-An Intriguing Example of Tumor Evolution at Play

Our understanding of neuroendocrine prostate cancer (NEPC) has assumed a new perspective in light of the recent advances in research. Although classical NEPC is rarely seen in the clinic, focal neuroendocrine trans-differentiation of prostate adenocarcinoma occurs in about 30% of advanced prostate cancer (PCa) cases, and represents a therapeutic challenge. Even though our knowledge of the mechanisms that mediate neuroendocrine differentiation (NED) is still evolving, the role of androgen deprivation therapy (ADT) as a key driver of this phenomenon is increasingly becoming evident. In this review, we discuss the molecular, cellular, and therapeutic mediators of NED, and emphasize the role of the tumor microenvironment (TME) in orchestrating the phenotype. Understanding the role of the TME in mediating NED could provide us with valuable insights into the plasticity associated with the phenotype, and reveal potential therapeutic targets against this aggressive form of PCa.

Nimesulide analogues: From anti-inflammatory to antitumor agents

Nimesulide is a nonsteroidal anti-inflammatory drug possessing analgesic and antipyretic properties. This drug is considered a selective cyclooxygenase-2 (COX-2) inhibitor and, more recently, has been associated to antitumor activity. Thus, numerous works have been developed to modify the nimesulide skeleton aiming to develop new and more potent and selective COX-2 inhibitors as well as potential anticancer agents. This review intends to provide an overview on analogues of nimesulide, including the general synthetic approaches used for their preparation and structural diversification and their main anti-inflammatory and/or antitumor properties.

MIF mediates bladder pain, not inflammation, in cyclophosphamide cystitis

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MIF mediates bladder pain but not bladder inflammation induced by CYP.

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ISO-1 blocks CYP induced bladder inflammation independent of MIF.

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MIF may mediate bladder pain by promoting bladder ERK phosphorylation.

Macrophage migration inhibitory factor (MIF), a proinflammatory mediator, is recognized as a player in inflammatory and neuropathic pain. Cyclophosphamide (CYP) results in bladder inflammation and pain and it’s a frequently used animal model of interstitial cystitis/bladder pain syndrome (IC/BPS). Because pretreatment with a MIF inhibitor (ISO-1) prevented both CYP-induced bladder pain and inflammation we used genetic MIF knockout (KO) mice to further investigate MIF’s role in CYP-induced bladder pain and inflammation. Abdominal mechanical threshold measured bladder pain induced by CYP in wild type (WT) and MIF KO mice at several time points (0–48 h). End-point (48 h) changes in micturition parameters and histological signs of bladder inflammation were also evaluated. Abdominal mechanical hypersensitivity developed within 4 h after CYP injection (and lasted for the entire observation period: 48 h) in WT mice. MIF KO mice, on the other hand, did not develop abdominal mechanical hypersensitivity suggesting that MIF is a pivotal molecule in mediating CYP-induced bladder pain. Both WT and MIF KO mice treated with CYP showed histological signs of marked bladder inflammation and showed a significant decrease in micturition volume and increase in frequency. Since both changes were blocked in MIF KO mice by pretreatment with a MIF inhibitor (ISO-1) it is likely these are non-specific effects of ISO-1. MIF mediates CYP-induced bladder pain but not CYP-induced bladder inflammation. The locus of effect (bladder) or central (spinal) for MIF mediation of bladder pain remains to be determined.

Macrophage migration inhibitory factor mediates protease-activated receptor 4-induced bladder pain through urothelial high mobility group box 1

Macrophage migration inhibitory factor (MIF) mediates pain although the mechanisms are not well understood. Urothelial activation of protease activated receptor 4 (PAR4) results in urothelial MIF release, urothelial high mobility group box 1 (HMGB1) release and bladder pain in mice without bladder inflammation. All three effects are prevented by MIF inhibition while intravesical disulfide HMGB1 alone can induce bladder pain. This study utilizes genetic MIF deletion to determine whether MIF mediates PAR4‐induced bladder pain and is upstream of HMGB1‐induced bladder pain. Wild type (C57/BL6) and MIF knockout (KO) mice were treated with intravesical PAR4 activating peptide or disulfide HMGB1 and tested for abdominal mechanical hypersensitivity at baseline (before treatment) and 24 h after injection. Micturition parameters and bladder histology were examined after behavioral test. Real‐time PCR and western blotting measured HMGB1 mRNA and protein levels in the bladders of naïve wild type and MIF KO mice, while immunofluorescence measured HMGB1 protein levels in the urothelium of both strains. Intravesical PAR4 activation resulted in abdominal mechanical hypersensitivity in wild‐type mice but not MIF KO mice. Intravesical disulfide HMGB1 induced abdominal mechanical hypersensitivity in both strains. Neither treatment resulted in significant changes in micturition or bladder histology in either strain. HMGB1 mRNA and protein levels were higher in MIF KO mouse bladders and the urothelium of MIF KO bladder had greater immunostaining than the wild‐type strain. MIF is a pivotal molecule mediating PAR4‐induced bladder pain and regulating urothelial HMGB1 production and release to elicit bladder pain.

Proteomic Analysis Shows Constitutive Secretion of MIF and p53-associated Activity of COX-2-/- Lung Fibroblasts

The differential expression of two closelyassociated cyclooxygenase isozymes, COX-1 and COX-2, exhibited functions beyond eicosanoid metabolism. We hypothesized that COX-1 or COX-2 knockout lung fibroblasts may display altered protein profiles which may allow us to further differentiate the functional roles of these isozymes at the molecular level. Proteomic analysis shows constitutive production of macrophage migration inhibitory factor (MIF) in lung fibroblasts derived from COX-2^−/− but not wild-type (WT) or COX-1^−/− mice. MIF was spontaneously released in high levels into the extracellular milieu of COX2^−/− fibroblasts seemingly from the preformed intracellular stores, with no change in the basal gene expression of MIF. The secretion and regulation of MIF in COX-2^−/− was “prostaglandin-independent.” GO analysis showed that concurrent with upregulation of MIF, there is a significant surge in expression of genes related to fibroblast growth, FK506 binding proteins, and isomerase activity in COX-2^−/− cells. Furthermore, COX-2^−/− fibroblasts also exhibit a significant increase in transcriptional activity of various regulators, antagonists, and co-modulators of p53, as well as in the expression of oncogenes and related transcripts. Integrative Oncogenomics Cancer Browser (IntroGen) analysis shows downregulation of COX-2 and amplification of MIF and/or p53 activity during development of glioblastomas, ependymoma, and colon adenomas. These data indicate the functional role of the MIF-COX-p53 axis in inflammation and cancer at the genomic and proteomic levels in COX-2-ablated cells. This systematic analysis not only shows the proinflammatory state but also unveils a molecular signature of a pro-oncogenic state of COX-1 in COX-2 ablated cells.

The COX-2-Selective Antagonist (NS-398) Inhibits Choroidal Neovascularization and Subretinal Fibrosis

Choroidal neovascularization (CNV) is an important pathologic component of neovascular age-related macular degeneration (AMD), and CNV lesions later develop into fibrous scars, which contribute to the loss of central vision. Nowadays, the precise molecular and cellular mechanisms underlying CNV and subretinal fibrosis have yet to be fully elucidated. Cyclooxygenase-2 (COX-2) has previously been implicated in angiogenesis and fibrosis. However, the role of COX-2 in the pathogenesis of CNV and subretinal fibrosis is poorly understood. The present study reveals several important findings concerning the relationship of COX-2 signaling with CNV and subretinal fibrosis. Experimental CNV lesions were attenuated by the administration of NS-398, a COX-2-selective antagonist. NS-398-induced CNV suppression was found to be mediated by the attenuation of macrophage infiltration and down-regulation of VEGF in the retinal pigment epithelium-choroid complex. Additionally, NS-398 attenuated subretinal fibrosis, in an experimental model of subretinal scarring observed in neovascular AMD, by down-regulation of TGF-β2 in the retinal pigment epithelium-choroid complex. Moreover, we cultured mouse RPE cells and found that NS-398 decreased the secretion of VEGF and TGF-β2 in mouse RPE cells. The results of the present study provide new findings regarding the molecular basis of CNV and subretinal fibrosis, and provide a proof-of-concept approach for the efficacy of COX-2 inhibition in treating subretinal fibrosis.

Macrophage migration inhibitory factor involvement in breast cancer (Review)

Macrophage migration inhibitory factor (MIF) is a pleiotropic inflammatory cytokine involved in many cellular processes and in particular carcinogenesis. Here, we review the experimental and clinical published data on MIF and its pathways in breast cancer. Experimental data show that MIF is overexpressed in breast cancer cells (BCC) due, at least partly, to its stabilization by HSP90 and upregulation by HIF-1α. MIF interacts with its main receptor CD74 and its co-receptor CXCR-4, both overexpressed, promoting cell survival by PI3K/Akt activation, a possible link with EGFR and HER2 pathways and inhibition of autophagy. Besides these auto- and paracrine effects on BCC, MIF interacts with BCC micro-environment by several mechanisms: immunomodulation by increasing the prevalence of immune suppressive cells, neo-angiogenesis by its link to HIF-1, and finally BCC transendothelial migration. Clinical studies show higher levels of MIF in breast cancer patients serum compared to healthy volunteers but without obvious clinical significance. In breast cancer tissue, MIF and CD74 are overexpressed in the cancer cells and in the stroma but correlations with classical prognostic factors or survival are elusive. However, an inverse correlation with the tumor size for stromal MIF and a positive correlation with the triple receptor negative tumor status for stromal CD74 seem to be showed. This set of experimental and clinical data shows the involvement of MIF pathways in breast carcinogenesis. Several anti-MIF targeted strategies are being explored in therapeutic goals and should merit further investigations.

Role of cyclooxygenase-2 in Trypanosoma cruzi survival in the early stages of parasite host-cell interaction

Chagas disease, caused by the intracellular protozoan Trypanosoma cruzi, is a serious health problem in Latin America. During this parasitic infection, the heart is one of the major organs affected. The pathogenesis of tissue remodelling, particularly regarding cardiomyocyte behaviour after parasite infection and the molecular mechanisms that occur immediately following parasite entry into host cells are not yet completely understood. When cells are infected with T. cruzi, they develop an inflammatory response, in which cyclooxygenase-2 (COX-2) catalyses rate-limiting steps in the arachidonic acid pathway. However, how the parasite interaction modulates COX-2 activity is poorly understood. In this study, the H9c2 cell line was used as our model and we investigated cellular and biochemical aspects during the initial 48 h of parasitic infection. Oscillatory activity of COX-2 was observed, which correlated with the control of the pro-inflammatory environment in infected cells. Interestingly, subcellular trafficking was also verified, correlated with the control of Cox-2 mRNA or the activated COX-2 protein in cells, which is directly connected with the assemble of stress granules structures. Our collective findings suggest that in the very early stage of the T. cruzi-host cell interaction, the parasite is able to modulate the cellular metabolism in order to survives.

Leading causes of castration-resistant prostate cancer

Prostate cancer (PCa) is the second leading cause of cancer-related death in men. Androgen receptor has a key role in the initiation and progression of PCa. Currently, androgen deprivation therapy is the standard treatment for PCa patients due to its effective suppression of androgen receptor signaling. Even though androgen deprivation therapy shows its initial effectiveness on shrinking tumor size, it eventually fails to cure advanced PCa, which is determined by the occurrence of castration-resistance. In this review, we summarize the widely accepted mechanisms that account for castration-resistant PCa and discuss potential therapeutic targets.

Linking inflammation and neuroendocrine differentiation: the role of macrophage migration inhibitory factor-mediated signaling in prostate cancer

A new paper by Tawadros et al. in Endocrine-Related Cancer demonstrates a link between macrophage migration inhibitory factor and neuroendocrine differentiation in prostate cancer. This paper may have implications in explaining the effect of prostatitis and chronic inflammation on the development of aggressive prostate cancer.

BMP-2 mediates PGE(2) -induced reduction of proliferation and osteogenic differentiation of human tendon stem cells

Tendon stem cells (TSCs) have been proposed to play a major role in the development of tendinopathy, which refers to pathological changes, such as calcification, in affected tendons. Using a human TSC (hTSC) culture model, this study investigated the effects of PGE(2) , an inflammatory mediator present in injured tendons, on hTSC proliferation and differentiation as well as the molecular mediator for such PGE(2) -induced effects. We found that PGE(2) treatment of hTSCs decreased cell proliferation and caused osteogenic differentiation of hTSCs in a dose-dependent manner. Also, PGE(2) treatment of hTSCs induced dose-dependent BMP-2 production in culture, and moreover, addition of BMP-2 to hTSC culture decreased cell proliferation and induced hTSC differentiation into osteoblasts. Finally, addition of BMP-2 antibodies to hTSC culture treated with PGE(2) nearly abolished PGE(2) effects on both cell proliferation and osteogenic differentiation. Taken together, the findings of this study showed that BMP-2 mediates PGE(2) -induced reduction of proliferation and osteogenic differentiation of hTSCs. We suggest that such a mechanism may be partially responsible for the formation of calcified tissues in tendinopathic tendons seen in clinical settings.

Neuroendocrine differentiation in prostate cancer: from lab to bedside

OBJECTIVES

To discuss the current knowledge on induction, production, sustenance and promotion of neuroendocrine differentiation in human prostate cancer.

METHODS

Review of the literature using PubMed search and scientific journal publications.

RESULTS

Morphological evidence explains some functional relationship between neuroendocrine and neoplastic surrounding cells. Transdifferentiation phenomenon and new biochemical pathways could be included in the development of androgen independence and prostate cancer progression.

CONCLUSION

Multiple evidence seems to confirm that a synergistic functional network between epithelial PSA secretory cells and neuroendocrine intraprostatic system is the main trigger for the induction and sustenance of neuroendocrine differentiation. The development of new antineoplastic molecules should consider the multiple interference of the intercellular network.

Tumor radiosensitization by antiinflammatory drugs: evidence for a new mechanism involving the oxygen effect

We hypothesized that nonsteroidal antiinflammatory drugs (NSAIDs) might enhance tumor radiosensitivity by increasing tumor oxygenation (pO2), via either a decrease in the recruitment of macrophages or from inhibition of mitochondrial respiration. The effect of four NSAIDs (diclofenac, indomethacin, piroxicam, and NS-398) on pO2 was studied in murine TLT liver tumors and FSaII fibrosarcomas. At the time of maximum pO2 (t(max), 30 minutes after administration), perfusion, oxygen consumption, and radiation sensitivity were studied. Local pO2 measurements were done using electron paramagnetic resonance. Tumor perfusion and permeability measurements were assessed by dynamic contrast-enhanced magnetic resonance imaging. The oxygen consumption rate of tumor cells after in vivo NSAID administration was measured using high-frequency electron paramagnetic resonance. Tumor-infiltrating macrophage localization was done with immunohistochemistry using CD11b antibody. All the NSAIDs tested caused a rapid increase in pO2. At t(max), tumor perfusion decreased, indicating that the increase in pO2 was not caused by an increase in oxygen supply. Also at t(max), global oxygen consumption decreased but the amount of tumor-infiltrating macrophages remained unchanged. Our study strongly indicates that the oxygen effect caused by NSAIDs is primarily mediated by an effect on mitochondrial respiration. When irradiation (18 Gy) was applied at t(max), the tumor radiosensitivity was enhanced (regrowth delay increased by a factor of 1.7). These results show the potential utility of an acute administration of NSAIDs for radiosensitizing tumors, and shed new light on the mechanisms of NSAID radiosensitization. These results also provide a new rationale for the treatment schedule when combining NSAIDs and radiotherapy.

Proteome profiling of interleukin-12 treated human T helper cells

Selective activation of T helper subsets 1 (Th1) and 2 (Th2) plays a crucial role in different pathological conditions. Th1 cell response is involved in pathogenesis of autoimmune diseases, such as type II diabetes and multiple sclerosis, and Th2 cell response in pathogenesis of allergy and asthma. Cytokine interleukin-12 (IL-12) is one of the key factors in the differentiation of naïve CD4(+) T cells into Th1 cells. In this study we used 2-DE and MS to find and identify IL-12 regulated proteins in human CD4(+) T cells. In total, 42 protein spots were found to be differentially expressed following IL-12 stimulation, of which 22 were up- and 20 down-regulated. Among the upregulated proteins there are a multifunctional cytokine macrophage migration inhibitory factor and a known IL-12 target gene Programmed cell death 4. Downregulated proteins include p21-activated kinase 2 and its upstream GTPase Cdc42. Compared to previous reports our analysis provides a new view on the IL-12 induced changes on CD4(+) T cells underscoring the importance of creating and combining the data generated at various levels to build a comprehensive view of a given biological process of the cell.

A human- and male-specific protocadherin that acts through the wnt signaling pathway to induce neuroendocrine transdifferentiation of prostate cancer cells

Protocadherin-PC (PCDH-PC) is a gene on the human Y chromosome that is selectively expressed in apoptosis- and hormone-resistant human prostate cancer cells. The protein encoded by PCDH-PC is cytoplasmically localized and has a small serine-rich domain in its COOH terminus that is homologous to the beta-catenin binding site of classical cadherins. Variants of prostate cancer cells that express PCDH-PC have high levels of nuclear beta-catenin protein and increased wnt-signaling. In this study, we show that transfection of human prostate cancer cells (LNCaP) with PCDH-PC or culture of these cells in androgen-free medium (a condition that up-regulates PCDH-PC expression) activates wnt signaling as assessed by nuclear accumulation of beta-catenin, increased expression of luciferase from a reporter vector promoted by Tcf binding elements and increased expression of wnt target genes. Moreover, LNCaP cells transfected with PCDH-PC or grown in androgen-free medium transdifferentiate to neuroendocrine-like cells marked by elevated expression of neuron-specific enolase and chromogranin-A. Neuroendocrine transdifferentiation was also observed when LNCaP cells were transfected by stabilized beta-catenin. Increased wnt signaling and neuroendocrine transdifferentiation of LNCaP cells induced by culture in androgen-free medium was suppressed by short interfering RNAs that target PCDH-PC as well as by dominant-negative Tcf or short interfering RNA against beta-catenin, supporting the hypothesis that increased expression of PCDH-PC is driving neuroendocrine transdifferentiation by activating wnt signaling. These findings have significant implications for the process through which prostate cancers progress to hormone resistance in humans.

Inhibition of macrophage migration inhibitory factor decreases proliferation and cytokine expression in bladder cancer cells

BACKGROUND

The importance of various inflammatory cytokines in maintaining tumor cell growth and viability is well established. Increased expression of the proinflammatory cytokine macrophage migration inhibitory factor (MIF) has previously been associated with various types of adenocarcinoma.

METHODS

MIF IHC was used to localize MIF in human bladder tissue. ELISA and Western blot analysis determined the synthesis and secretion of MIF by human bladder transitional cell carcinoma cells. The effects of MIF inhibitors (high molecular weight hyaluronate (HA), anti-MIF antibody or MIF anti-sense) on cell growth and cytokine expression were analyzed.

RESULTS

Human bladder cancer cells (HT-1376) secrete detectable amounts of MIF protein. Treatment with HA, anti-MIF antibody and MIF anti-sense reduced HT-1376 cell proliferation, MIF protein secretion, MIF gene expression and secreted inflammatory cytokines. Our evidence suggests MIF interacts with the invariant chain, CD74 and the major cell surface receptor for HA, CD44.

CONCLUSIONS

This study is the first to report MIF expression in the human bladder and these findings support a role for MIF in tumor cell proliferation. Since MIF participates in the inflammatory response and bladder cancer is associated with chronic inflammatory conditions, these new findings suggest that neutralizing bladder tumor MIF may serve as a novel therapeutic treatment for bladder carcinoma.

Proliferation of prostate cancer cells and activity of neutral endopeptidase is regulated by bombesin and IL-1beta with IL-1beta acting as a modulator of cellular differentiation

BACKGROUND

Neutral endopeptidase (NEP) is a cell-surface bound enzyme that cleaves and inactivates neuropeptides such as bombesin and substance P and is involved in the transition from hormonally regulated androgen-dependent prostate cancer (PC) to androgen-independent PC. Neuropeptides are implicated in growth regulation of different cell types and function as transmitters between the neuroendocrine and the immune system.

METHODS

NEP-expression, enzymatic activity of the membrane bound protein, cell proliferation, procalcitonin (PCT) production, and secretion as well as changes in cell morphology of prostatic cells were evaluated after treatment with the immunomodulatory cytokine interleukin-1beta (IL-1beta), neuropeptides (bombesin, substance P), and neuropeptide-conditioned media derived from a human neuroendocrine cell line.

RESULTS

Incubation of LNCaP tumor cells with IL-1beta resulted in a diminished proliferative activity, induction of neurite-like outgrowth which was accompanied by the formation of tubular-type mitochondria typical for neuronal/neuroendocrine cells, and an increased production and secretion of PCT. Conversely, proliferation of prostatic stromal cells was enhanced by the cytokine coming along with an increased number of Golgi-apparatuses and ER-cisternae. Bombesin had an antimitotic effect on LNCaP, but not on stromal cells. Substance P did not influence the growth of any of the cell types investigated, whereas neuropeptide-conditioned media exerted a slightly mitogenic effect on both cell types. The activity of LNCaP cell-surface bound NEP was enhanced by bombesin, but was diminished by substance P and neuropeptide-conditioned media.

CONCLUSIONS

Proliferation and activity of neuropeptide degrading NEP is regulated differently by immunomodulatory substances in PC cells and cells derived from the prostatic stroma with IL-1beta being a potent modulator of cellular differentiation and a potential target for anticancer drug design in PC cells.

Macrophage Migration Inhibitory Factor Is Upregulated in an Endotoxin-Induced Model of Bladder Inflammation in Rats

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine found in epithelial cells as preformed stores, such that MIF release can activate innate immune responses. Our identification of MIF stores in the urothelium suggests that MIF may function in the bladder's initial response to infectious stimuli, such as lipopolysaccharide (LPS). To test this hypothesis, we observed changes in MIF, cyclooxygenase-2 (COX-2) and c-fos in the bladder, L6-S1 spinal cord, dorsal root ganglion (DRG), and major pelvic ganglion (MPG) and MIF changes in the prostate following intravesical LPS. Intravesical LPS induced bladder edema and leukocyte infiltration, as well as increased MIF protein and mRNA in the bladder and lumbosacral spinal cord. Expression of immediate-early gene c-fos, a transcription factor used as a marker of neuronal activation, increased in the L6-S1 spinal cord and L6-S1 DRG of rats that received LPS. We conclude that significant increases in bladder MIF expression and protein in response to intravesical LPS may represent part of this organ's initial innate immune response. In addition, MIF upregulation may represent a neural response to visceral inflammation. Finally, changes in prostate MIF content after intravesical LPS suggest that MIF may be involved in viscerovisceral interactions associated with chronic pelvic pain syndromes.

Hydrochloric acid induced changes in macrophage migration inhibitory factor in the bladder, peripheral and central nervous system of the rat

PURPOSE

We established the presence of the proinflammatory cytokine macrophage migration inhibitory factor (MIF) in the bladder and in nervous system structures innervating the bladder, and evaluated changes in MIF and cyclooxygenase-2 (COX-2) protein levels and expression following chemical cystitis.

MATERIALS AND METHODS

Male Sprague-Dawley rats were anesthetized and a catheter was introduced into the bladder dome. Cystitis was induced by infusing 0.4 N HCl into the bladder. Control rats received a similar volume of saline. Two hours later the bladder, major pelvic ganglia (MPG), L6/S1 dorsal root ganglia (DRG) and L6/S1 spinal cord were removed and assayed for MIF and COX-2 protein, and mRNA using Western blot and quantitative reverse transcriptase-polymerase chain reaction techniques.

RESULTS

Immunohistochemistry showed MIF located mainly in the urothelium of saline treated rats. Instillation of HCl into the bladder resulted in marked epithelial denudation, moderate edema and vasodilatation in the submucosa. MIF protein levels decreased but MIF mRNA expression remained unchanged in bladders treated with HCl compared with controls. However, MIF protein and mRNA levels increased in the MPG, L6/S1 DRG and L6/S1 spinal cord of HCl treated animals. COX-2 protein was not detected in the bladder, DRG or MPG of saline-treated rats. However, a small amount was present in the L6/S1 cord. On the other hand, HCl treated rats showed marked increases in COX-2 protein levels in all tissues examined. Similarly although cox-2 mRNA was constitutively expressed in all tissues examined, expression increased following HCl treatment.

CONCLUSIONS

Chemical cystitis induced by intravesical HCl in rats increases the protein levels and mRNA expression of MIF and COX-2 in central and peripheral nervous system tissues that are involved in innervating the bladder. This finding suggests that MIF may be involved in bladder inflammation and may have a role in the peripheral and central nervous system pathways that regulate bladder reflexes in response to bladder inflammation.