Cytokine gene expression in a mouse model: the first instillations with viable bacillus Calmette-Guerin determine the succeeding Th1 response

Mycolicibacterium brumae Is a Safe and Non-Toxic Immunomodulatory Agent for Cancer Treatment

Intravesical Mycobacterium bovis Bacillus Calmette-Guérin (BCG) immunotherapy remains the gold-standard treatment for non-muscle-invasive bladder cancer patients, even though half of the patients develop adverse events to this therapy. On exploring BCG-alternative therapies, Mycolicibacterium brumae, a nontuberculous mycobacterium, has shown outstanding anti-tumor and immunomodulatory capabilities. As no infections due to M. brumae in humans, animals, or plants have been described, the safety and/or toxicity of this mycobacterium have not been previously addressed. In the present study, an analysis was made of M. brumae- and BCG-intravenously-infected severe combined immunodeficient (SCID) mice, M. brumae-intravesically-treated BALB/c mice, and intrahemacoelic-infected-Galleria mellonella larvae. Organs from infected mice and the hemolymph from larvae were processed to count bacterial burden. Blood samples from mice were also taken, and a wide range of hematological and biochemical parameters were analyzed. Finally, histopathological alterations in mouse tissues were evaluated. Our results demonstrate the safety and non-toxic profile of M. brumae. Differences were observed in the biochemical, hematological and histopathological analysis between M. brumae and BCG-infected mice, as well as survival curves rates and colony forming units (CFU) counts in both animal models. M. brumae constitutes a safe therapeutic biological agent, overcoming the safety and toxicity disadvantages presented by BCG in both mice and G. mellonella animal models.

The role of cancer stem cells in immunotherapy for bladder cancer: An in vitro study

OBJECTIVE

Bladder cancer is characterized by frequent recurrence and progression. CD44+ cancer stem cells (CSCs) might be one of the main reasons for recurrence. Although Bacillus Calmette Guerin (BCG) has become a gold standard immunotherapy, after treatment recurrence frequently occur. Based on this knowledge, the aim of this study was to evaluate the changes in cytokine and chemokine expressions in bladder cancer and CSCs cultures in vitro with BCG only and in combination with IL2 and lymphocyte (MNCs) applications.

MATERIAL AND METHODS

In this study, 3 cell lines of human bladder cancer cells with different characteristics (T24, 5637, and JMSU-1) and CD44+ bladder CSCs isolated by magnetic bead isolation (Miltenyl Magtech) were used. Bladder cancer cell lines and bladder CSCs in complete medium were cultured under humidified conditions of 37°C temperature in 5% CO₂. BCG only and its combination with IL2 and MNCs were applied to bladder cancer cell lines and bladder CSCs for 24, 48, and 72 hours. Annexin V-PI was used to detect the percentages of apoptotic and necrotic cells in treatment groups and control groups. After treatments, total RNAs were isolated and converted to cDNA for each group and controls. Quantitative fold changes in terms of gene expression were measured by RT2-PCR array and fold changes for expression levels of genes were compared among groups. Eighty-four genes were analyzed in standard array of chemokines and cytokines (Biorad).

RESULTS

BCG treatment with 7.32 µg/ml dose alone and in combination with IL2 (1000 IU/ml) and MNCs (1000 cells/ml) were found to be most effective on bladder cancer cells. When BCG and its combinations were applied to CSCs of the 3 cell lines, BCG treatment showed cytotoxic effect on CSCs as well as cancer cells. CSCs of 3 cell lines over expressed CXCL5, CCL8, CNTF, and CSF2 compared with cancer cells. Cancer cells over expressed IL6, TNSFF11, FASLG, and CXCL9 compared with CSCs. In all 3 cell lines, BCG application increased expression of CXCL5 and LTB and also decreased CCL20 and IL6. When BCG was combined with IL2 and MNCs, CXCL10, CXCL5, and IFNG were increased and CXCL12, IL6, and TNSF11 were decreased. BCG treatment of CSCs caused increases in ADIPOQ, CXCL10, and XCL1 and a decrease in CCL8. When IL2 and MNCs were combined with BCG, the expression of many cytokines and chemokines decreased.

CONCLUSION

BCG treatment changes the expression of many cytokines and chemokines in bladder cancer. The expression differs in 3 different cell lines and their CSCs. Immune modulation of each case differs from each other. The effectivity of BCG-based immunotherapy in bladder cancer on CSCs might decrease in combination with IL2. Our results indicate that recurrence after BCG treatment for bladder cancer may not occur mainly based on the CSCs hypothesis considering bladder cancer occurs at different loci of surface epithelium.

Bacillus Calmette-Guérin induces rapid gene expression changes in human bladder cancer cell lines that may modulate its survival

Bacillus Calmette-Guérin (BCG) immunotherapy is the standard therapy for non-muscle invasive bladder cancer. The aim of the present study was to identify genes that are induced in response to BCG immunotherapy, as these may be potential biomarkers for the response to clinical therapy. To model clinical therapy, human bladder cancer cell lines were incubated with BCG (live or lyophilized BCG Connaught) for 2 h. RNA was extracted and evaluated by Representational Differential Analysis (RDA) and oligo arrays. Gene expression was confirmed by reverse transcription polymerase chain reaction on fresh cell lines with differential abilities to internalize BCG. The effect of 2 major BCG soluble proteins, antigen 85B (Ag85B) and Mycobacterium protein tyrosine phosphatase A (MptpA) and BCG Tice^® on gene expression was also determined. GAPDH and β-actin, which are normally used as control genes, were upregulated by BCG. Therefore, the ribosomal RNA gene ribosomal protein S27a was used to normalize gene expression. The genes likely to be induced by BCG internalization and soluble factors were: GSTT2, MGST2, CCL20, TNFα, CCNE1 and IL10RB. Those induced by BCG membrane interactions and/or soluble factors were: MGST1, CXCL6, IL12A, CSF2, IL1β and TOLLIP. MptpA decreased GSTT2 expression, and Ag85B increased TNFα expression. The two BCG strains significantly increased GSTT2, TNFα and TOLLIP levels in MGH cells. However, in J82 cells there was a BCG strain-dependent difference in TNFα expression. An important outcome of the present study was the determination that neither GAPDH nor β-actin were suitable control genes for the analysis of BCG-induced gene expression. BCG Connaught and Tice^® induced similar expression levels of genes in bladder cancer cell lines. BCG soluble proteins modulated gene expression and therefore may affect therapeutic outcomes. The genes identified may be novel biomarkers of the response to BCG therapy.

Mycobacteria emulsified in olive oil-in-water trigger a robust immune response in bladder cancer treatment

The hydrophobic composition of mycobacterial cell walls leads to the formation of clumps when attempting to resuspend mycobacteria in aqueous solutions. Such aggregation may interfere in the mycobacteria-host cells interaction and, consequently, influence their antitumor effect. To improve the immunotherapeutic activity of Mycobacterium brumae, we designed different emulsions and demonstrated their efficacy. The best formulation was initially selected based on homogeneity and stability. Both olive oil (OO)- and mineral oil-in-water emulsions better preserved the mycobacteria viability and provided higher disaggregation rates compared to the others. But, among both emulsions, the OO emulsion increased the mycobacteria capacity to induce cytokines’ production in bladder tumor cell cultures. The OO-mycobacteria emulsion properties: less hydrophobic, lower pH, more neutralized zeta potential, and increased affinity to fibronectin than non-emulsified mycobacteria, indicated favorable conditions for reaching the bladder epithelium in vivo. Finally, intravesical OO-M. brumae-treated mice showed a significantly higher systemic immune response, together with a trend toward increased tumor-bearing mouse survival rates compared to the rest of the treated mice. The physicochemical characteristics and the induction of a robust immune response in vitro and in vivo highlight the potential of the OO emulsion as a good delivery vehicle for the mycobacterial treatment of bladder cancer.

γ Irradiated Mycobacteria Enhance Survival in Bladder Tumor Bearing Mice Although Less Efficaciously than Live Mycobacteria

PURPOSE

γ Irradiated Mycobacterium bovis bacillus Calmette-Guérin has shown in vitro and ex vivo antitumor activity. However, to our knowledge the potential antitumor capacity has not been demonstrated in vivo. We studied the in vivo potential of γ irradiated bacillus Calmette-Guérin and γ irradiated M. brumae, a saprophytic mycobacterium that was recently described as an immunotherapeutic agent.

MATERIALS AND METHODS

The antitumor capacity of γ irradiated M. brumae was first investigated by analyzing the in vitro inhibition of bladder tumor cell proliferation and the ex vivo cytotoxic effect of M. brumae activated peripheral blood cells. The effect of γ irradiated M. brumae or bacillus Calmette-Guérin intravesical treatment was then compared to treatment with live mycobacteria in the orthotopic murine model of bladder cancer.

RESULTS

Nonviable M. brumae showed a capacity to inhibit in vitro bladder cancer cell lines similar to that of live mycobacteria. However, its capacity to induce cytokine production was decreased compared to that of live M. brumae. γ Irradiated M. brumae could activate immune cells to inhibit tumor cell growth, although to a lesser extent than live mycobacteria. Finally, intravesical treatment with γ irradiated M. brumae or bacillus Calmette-Guérin significantly increased survival with respect to that of nontreated tumor bearing mice. Both γ irradiated mycobacteria showed lower survival rates than those of live mycobacteria but the minor efficacy of γ irradiated vs live mycobacteria was only significant for bacillus Calmette-Guérin.

CONCLUSIONS

Our results show that although γ irradiated mycobacteria is less efficacious than live mycobacteria, it induces an antitumor effect in vivo, avoiding the possibility of further mycobacterial infections.

Nonpathogenic Mycobacterium brumae Inhibits Bladder Cancer Growth In Vitro, Ex Vivo, and In Vivo

BACKGROUND

Bacillus Calmette-Guérin (BCG) prevents tumour recurrence and progression in non-muscle-invasive bladder cancer (BC). However, common adverse events occur, including BCG infections.

OBJECTIVE

To find a mycobacterium with similar or superior antitumour activity to BCG but with greater safety.

DESIGN

In vitro, ex vivo, and in vivo comparisons of the antitumour efficacy of nonpathogenic mycobacteria and BCG.

INTERVENTION

The in vitro antitumour activity of a broad set of mycobacteria was studied in seven different BC cell lines. The most efficacious was selected and its ex vivo capacity to activate immune cells and its in vivo antitumour activity in an orthotopic murine model of BC were investigated.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Growth inhibition of BC cells was the primary outcome measurement. Parametric and nonparametric tests were use to analyse the in vitro results, and a Kaplan-Meier test was applied to measure survival in mycobacteria-treated tumour-bearing mice.

RESULTS AND LIMITATIONS

Mycobacterium brumae is superior to BCG in inhibiting low-grade BC cell growth, and has similar effects to BCG against high-grade cells. M. brumae triggers an indirect antitumour response by activating macrophages and the cytotoxic activity of peripheral blood cells against BC cells. Although no significant differences were observed between BCG and M. brumae treatments in mice, M. brumae treatment prolonged survival in comparison to BCG treatment in tumour-bearing mice. In contrast to BCG, M. brumae does not persist intracellularly or in tumour-bearing mice, so the risk of infection is lower.

CONCLUSIONS

Our preclinical data suggest that M. brumae represents a safe and efficacious candidate as a therapeutic agent for non-muscle-invasive BC.

PATIENT SUMMARY

We investigated the antitumour activity of nonpathogenic mycobacteria in in vitro and in vivo models of non-muscle-invasive bladder cancer. We found that Mycobacterium brumae effectively inhibits bladder cancer growth and helps the host immune system to eradicate cancer cells, and is a promising agent for antitumour immunotherapy.

The quantum of initial transformed cells potentially modulates the type of local inflammation mechanism elicited by surrounding normal epithelial tissues and systemic immune pattern for tumor arrest or progression

The immune/ inflammation system potentially serves to arrest, eliminate or promote tumor development. Nonetheless, factors that dictate the choice are not comprehensively known yet. Using a B16/F1 syngeneic wild type model, we evaluated the essentiality of initial transformed cells' density for overt tumor development, the molecular trends of inflammatory mediators in the normal tumor-adjacent epithelial tissues (NTAT), and how such local events may reflect systematically in the host. Overt tumors developed, within an observatory period of at least 45 days and 90 days at most, only in mice inoculated with cancer cells above a limiting threshold of 1× 10(3) cells. Immunoblots showed early, intense and transient presence of IL-1β, IFN-γ, and both the all-thiol and disulfide forms of HMGB1 in the NTAT of non-tumor bearing mice. However, all-thiol form of HMGB1 and delayed but aberrant IL-6 expression characterized chronic inflammation in tumor bearing hosts. These local epithelial tissue events uniquely reflected in host's systemic cytokines dynamics where stable Th1/Th2 signature (IFN-γ/ IL-4) coupled with early Th1 cells polarization (IL-12/ IL-4) evidenced in non-tumor hosts but highly fluctuating Th1/ Th2 profile in tumor hosts, even before tumors became overt. This hypothesizes that the physical quantum of transformed cells that may either spontaneously arise or accrue at a locus may be crucial in orchestrating the mechanism for the type of local epithelial tissue and systemic immune/ inflammatory responses essential for tumor progression or arrest.

Killed but metabolically active Mycobacterium bovis bacillus Calmette-Guérin retains the antitumor ability of live bacillus Calmette-Guérin

PURPOSE

Mycobacterium bovis bacillus Calmette-Guérin is the most effective treatment for high risk noninvasive bladder cancer. Although bacillus Calmette-Guérin immunotherapy clearly decreases recurrence and progression rates, side effects are common and infection with the bacillus has been described. For these reasons it is necessary to find safer alternatives to the live bacillus. We explored the possibility of using killed but metabolically active bacillus Calmette-Guérin.

MATERIALS AND METHODS

T24, J82 and RT4 bladder tumor cell lines were cultured with live and irradiation or heat treated bacillus Calmette-Guérin Connaught. We measured the inhibition of cell proliferation and the production of cytokines in cell culture supernatants. Peripheral mononuclear blood cells were also infected and the production of different cytokines in cell culture supernatants was analyzed. Peripheral blood mononuclear cell and cell culture supernatants activated by mycobacteria were then cultured with T24 cells to analyze whether they showed cytotoxic activity.

RESULTS

Compared to the other bacillus Calmette-Guérin treatments, γ irradiated bacillus Calmette-Guérin showed activity similar to that of the live bacillus for inhibiting tumor growth and inducing cytokine production. Irradiated bacillus Calmette-Guérin showed metabolic activity and, thus, was considered killed but metabolically active. This is the treatment that most accurately preserved the mycobacterial structure. Killed but metabolically active bacillus Calmette-Guérin induced cytokine production by infected peripheral mononuclear blood cells. Mycobacteria activated peripheral blood mononuclear cell and cell supernatants showed cytotoxic activity against tumor cells, retaining the antitumor capacity of the live bacillus.

CONCLUSIONS

Our results suggest that killed but metabolically active bacillus Calmette-Guérin could be considered a safer immunotherapy alternative to treatment with the live bacillus.

From infection to immunotherapy: host immune responses to bacteria at the bladder mucosa

The pathogenesis of urinary tract infection and mechanisms of the protective effect of Bacillus Calmette-Guerin (BCG) therapy for bladder cancer highlight the importance of studying the bladder as a unique mucosal surface. Innate responses to bacteria are reviewed, and although our collective knowledge remains incomplete, we discuss how adaptive immunity may be generated following bacterial challenge in the bladder microenvironment. Interestingly, the widely held belief that the bladder is sterile has been challenged recently, indicating the need for further study of the impact of commensal microorganisms on the immune response to uropathogen infection or intentional instillation of BCG. This review addresses the aspects of bladder biology that have been well explored and defines what still must be discovered about the immunobiology of this understudied organ.

Antitumor effects of human interferon-alpha 2b secreted by recombinant bacillus Calmette-Guérin vaccine on bladder cancer cells

OBJECTIVE

Our objective was to construct a recombinant bacillus Calmette-Guérin vaccine (rBCG) that secretes human interferon-alpha 2b (IFNα-2b) and to study its immunogenicity and in vitro antitumor activity against human bladder cancer cell lines T24 and T5637.

METHODS

The signal sequence BCG Ag85B and the gene IFNα-2b were amplified from the genome of BCG and human peripheral blood, respectively, by polymerase chain reaction (PCR). The two genes were cloned in Escherichia coli-BCG shuttle-vector pMV261 to obtain a new recombinant plasmid pMV261-Ag85B-IFNα-2b. BCG was transformed with the recombinant plasmid by electroporation and designated rBCG-IFNα-2b. Mononuclear cells were isolated from human peripheral blood (PBMCs) and stimulated with rBCG-IFNα-2b or wild type BCG for 3 d, and then cultured with human bladder cancer cell lines T24 and T5637. Their cytotoxicities were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.

RESULTS

BCG was successfully transformed with the recombinant plasmid pMV261-Ag85B-IFNα-2b by electroporation and the recombinant BCG (rBCG-IFNα-2b) was capable of synthesizing and secreting cytokine IFNα-2b. PBMC proliferation was enhanced significantly by rBCG-IFNα-2b, and the cytotoxicity of PBMCs stimulated by rBCG-IFNα-2b to T24 and T5627 was significantly stronger in comparison to wild type BCG.

CONCLUSIONS

A recombinant BCG, secreting human IFNα-2b (rBCG-IFNα-2b), was constructed successfully and was superior to control wild type BCG in inducing immune responses and enhancing cytotoxicity to human bladder cancer cell lines T24 and T5637. This suggests that rBCG-IFNα-2b could be a promising agent for bladder cancer patients in terms of possible reductions in both clinical dosage and side effects of BCG immunotherapy.

Enhanced antitumor effect of combination intravesical mitomycin C and bacillus Calmette-Guerin therapy in an orthotopic bladder cancer model

Intravesical immunotherapy with bacillus Calmette-Guerin (BCG) is currently the most successful adjuvant agent for the treatment and/or prophylaxis of non-muscle-invasive bladder cancer (NMIBC). However, NMIBCs recur in 60-70% of cases and 30% of these recurrent tumors present with a higher grade and more invasive properties. Patients that do not respond to intravesical BCG therapy are considered to be a challenge for urologists. Thus, novel conservative possibilities should be explored. To test the efficacy of a novel therapeutic approach, we examined the antitumor effect of combination therapy by intravesical administration of mitomycin C (MMC) plus BCG, infusing the two drugs simultaneously, in an orthotopic bladder cancer model. Intravesical BCG and MMC administration showed a dose-dependent survival (n=8 per group). The combination of MMC and BCG provided a significant survival advantage compared to the BCG-alone (p=0.035) and MMC-alone groups (p=0.040) (n=8 per group). The group with combined MMC/BCG exhibited a survival period similar to that achieved with an amount eight times higher that of BCG (n=10 per group). Ki-67 labeling index of cancer cells, showing tumor proliferation, was significantly lower in the combined group compared to the BCG-alone (p<0.05), MMC-alone (p<0.01) and control groups (p<0.01). No difference was detected between the combined group and the BCG-alone group with regard to CD3, T-cell infiltration and CD68 macrophage activity. The combined MMC/BCG treatment decreased the tumor appearance rate, improved the survival period and reduced the cellular proliferation rate in tumors compared to the BCG-alone treatment. The results suggest that the combined intravesical MMC/BCG treatment induced an enhanced antitumor effect against bladder tumors. The combined MMC/BCG treatment also showed a survival period similar to that achieved using a dose eight times higher of BCG-alone.

Bacillus Calmette-Guérin treatment of non-muscle invasive bladder cancer

Bacillus Calmette-Guérin (BCG) has been used in the intravesical treatment of non-muscle invasive bladder cancer (NMIBC) for nearly 35 years; however, its use is still subject to controversy. The objective of this paper is to review the role of BCG in the treatment of patients with NMIBC. Clinical trials, meta-analyses and guidelines related to the administration, safety and efficacy of intravesical BCG were reviewed. Intravesical BCG is more effective than intravesical chemotherapy in decreasing the risk of recurrence and progression to muscle invasive disease; however, it is associated with more local and systemic side-effects. It is the gold standard in patients at high risk of progression. Maintenance BCG is required in order to achieve the best therapeutic results; however, the optimal dose, induction and maintenance schedules, and duration of treatment are unknown and might be different for each patient. Patients failing BCG treatment have a poor prognosis, and cystectomy is then the recommended treatment. Patients at low risk of recurrence and progression should not receive BCG, because of its side effects. Intermediate-risk patients might be treated with either intravesical chemotherapy or BCG; however, for patients at high risk of progression, BCG is recognized as the treatment of choice. Further research is urgently needed to identify markers associated with BCG failure and to develop effective alternatives to cystectomy in patients failing BCG.

Bacillus Calmette-Guerin immunotherapy for urothelial carcinoma of the bladder

Mycobacterium bovis bacille Calmette-Guerin (BCG) is one of the great success stories of immunotherapy as a treatment for superficial urothelial carcinoma of the bladder. Despite clinical effectiveness in over 50% of patients, the high incidence of local side effects and presence of nonresponders has led to efforts to improve the therapy. Recent advances have suggested a role for neutrophils and TNF-related apoptosis-inducing ligand (TRAIL) in the antitumor inflammatory response. Cell wall components of mycobacteria alone, lowered doses of BCG, and combination with cytokines have been studied as ways to improve the immune response associated with BCG and/or reduce toxicity. This review will discuss the clinical use of BCG, its proposed mechanism of action, and directions of future research to improve efficacy and decrease side effects.

Intravesical Toll-like receptor 7 agonist R-837: optimization of its formulation in an orthotopic mouse model of bladder cancer

OBJECTIVE

To study the immune response caused by the intravesical administration of the immunomodulator R-837 in various formulations and to estimate its therapeutic potential for bladder cancer.

METHODS

Female C57BL/6 mice were intravesically treated with different formulations of R-837, a Toll-like receptor 7 agonist used for treating genital warts and skin malignancy. The tested formulation mixtures contained different ratios of lactic acid, a thermosensitive poloxamer polymer (Lutrol F127) and 2-(hydroxypropyl)-beta-cyclodextrin (HPbetaCD). Induction of tumor necrosis factor alpha (TNFalpha) and keratinocyte-derived chemokine (KC) was analyzed by Luminex microbeads assay. The therapeutic potential of intravesical administration of R-837 was assessed in an orthotopic, syngeneic mouse model of bladder cancer using MB49 cells.

RESULTS

Intravesical administration of R-837 in lactic acid alone induced systemic and bladder TNFalpha and KC in a dose-dependent manner. Formulations including poloxamer decreased systemic absorption of R-837 and significantly reduced systemic and local induction of KC. Addition of HPbetaCD in the poloxamer formulation particularly reversed levels of systemic and local levels of TNFalpha and KC. Histological examination showed that poloxamer-HPbetaCD formulation allowed infiltration of mononuclear cells into urothelium and lamina propria. In studies using orthotopic mouse bladder cancer, the tumor loads in R-837-treated mice were significantly lower than those in vehicle-treated or non-treated mice.

CONCLUSION

The optimized poloxamer-HPbetaCD formulation of R-837 shows therapeutic potential for bladder cancer while avoiding adverse side-effects.

Molecular networks discriminating mouse bladder responses to intravesical bacillus Calmette-Guerin (BCG), LPS, and TNF-alpha

Background

Despite being a mainstay for treating superficial bladder carcinoma and a promising agent for interstitial cystitis, the precise mechanism of Bacillus Calmette-Guerin (BCG) remains poorly understood. It is particularly unclear whether BCG is capable of altering gene expression in the bladder target organ beyond its well-recognized pro-inflammatory effects and how this relates to its therapeutic efficacy. The objective of this study was to determine differentially expressed genes in the mouse bladder following chronic intravesical BCG therapy and to compare the results to non-specific pro inflammatory stimuli (LPS and TNF-α). For this purpose, C57BL/6 female mice received four weekly instillations of BCG, LPS, or TNF-α. Seven days after the last instillation, the urothelium along with the submucosa was removed from detrusor muscle and the RNA was extracted from both layers for cDNA array experiments. Microarray results were normalized by a robust regression analysis and only genes with an expression above a conditional threshold of 0.001 (3SD above background) were selected for analysis. Next, genes presenting a 3-fold ratio in regard to the control group were entered in Ingenuity Pathway Analysis (IPA) for a comparative analysis in order to determine genes specifically regulated by BCG, TNF-α, and LPS. In addition, the transcriptome was precipitated with an antibody against RNA polymerase II and real-time polymerase chain reaction assay (Q-PCR) was used to confirm some of the BCG-specific transcripts.

Results

Molecular networks of treatment-specific genes generated several hypotheses regarding the mode of action of BCG. BCG-specific genes involved small GTPases and BCG-specific networks overlapped with the following canonical signaling pathways: axonal guidance, B cell receptor, aryl hydrocarbon receptor, IL-6, PPAR, Wnt/β-catenin, and cAMP. In addition, a specific detrusor network expressed a high degree of overlap with the development of the lymphatic system. Interestingly, TNF-α-specific networks overlapped with the following canonical signaling pathways: PPAR, death receptor, and apoptosis. Finally, LPS-specific networks overlapped with the LPS/IL-1 mediated inhibition of RXR. Because NF-kappaB occupied a central position in several networks, we further determined whether this transcription factor was part of the responses to BCG. Electrophoretic mobility shift assays confirmed the participation of NF-kappaB in the mouse bladder responses to BCG. In addition, BCG treatment of a human urothelial cancer cell line (J82) also increased the binding activity of NF-kappaB, as determined by precipitation of the chromatin by a NF-kappaB-p65 antibody and Q-PCR of genes bearing a NF-kappaB consensus sequence. Next, we tested the hypothesis of whether small GTPases such as LRG-47 are involved in the uptake of BCG by the bladder urothelium.

Conclusion

As expected, BCG treatment induces the transcription of genes belonging to common pro-inflammatory networks. However, BCG also induces unique genes belonging to molecular networks involved in axonal guidance and lymphatic system development within the bladder target organ. In addition, NF-kappaB seems to play a predominant role in the bladder responses to BCG therapy. Finally, in intact urothelium, BCG-GFP internalizes in LRG-47-positive vesicles.

These results provide a molecular framework for the further study of the involvement of immune and nervous systems in the bladder responses to BCG therapy.

Expression of chemokine/cytokine genes and immune cell recruitment following the instillation of Mycobacterium bovis, bacillus Calmette-Guérin or Lactobacillus rhamnosus strain GG in the healthy murine bladder

Mycobacterium bovis, bacillus Calmette-Guérin (BCG) is the current gold standard for bladder cancer therapy. In this study a profile of the gene expression changes that occur after BCG instillation in the bladders of healthy mice was produced and compared to the type of immune cells recruited into the bladder. A similar comparison was made for Lactobacillus rhamnosus strain GG (LGG) instillations in healthy mice to determine its potential in the immunotherapy of bladder cancer. Mice were given six weekly instillations and were killed after the fourth, fifth and sixth instillations of BCG or LGG. Their bladders were harvested for chemokine/cytokine messenger RNA analysis using an array as well as semi-quantitative reverse transcription-polymerase chain reaction. In a second set of mice both the bladder and draining lymph nodes were harvested for the analysis of immune cells. BCG significantly upregulated genes for T helper type 1 (Th1) chemokines: Cxcl2, Cxcl9, Cxcl10, Xcl1; and increased the expression of Th1/Th2 chemokines: RANTES, Ccl6 and Ccl7; Th1 polarizing cytokines: Il1beta and Tnfa; and Fcgammar1 and iNOS as early as after four weekly instillations. Most of these genes remained highly expressed after 6 weeks. In contrast, LGG transiently induced Cxcl10, Il16, Fcepsilonr1 and Il1r2. Despite these findings, LGG instillation induced the recruitment of natural killer cells into the bladder and draining lymph nodes, as was observed for BCG instillation.

Discriminators of mouse bladder response to intravesical Bacillus Calmette-Guerin (BCG)

Background

Intravesical Bacillus Calmette-Guerin (BCG) is an effective treatment for bladder superficial carcinoma and it is being tested in interstitial cystitis patients, but its precise mechanism of action remains poorly understood. It is not clear whether BCG induces the release of a unique set of cytokines apart from its pro-inflammatory effects. Therefore, we quantified bladder inflammatory responses and alterations in urinary cytokine protein induced by intravesical BCG and compared the results to non-specific pro-inflammatory stimuli (LPS and TNF-α). We went further to determine whether BCG treatment alters cytokine gene expression in the urinary bladder.

Methods

C57BL/6 female mice received four weekly instillations of BCG, LPS, or TNF-α. Morphometric analyses were conducted in bladders isolated from all groups and urine was collected for multiplex analysis of 18 cytokines. In addition, chromatin immune precipitation combined with real-time polymerase chain reaction assay (CHIP/Q-PCR) was used to test whether intravesical BCG would alter bladder cytokine gene expression.

Results

Acute BCG instillation induced edema which was progressively replaced by an inflammatory infiltrate, composed primarily of neutrophils, in response to weekly administrations. Our morphological analysis suggests that these polymorphonuclear neutrophils are of prime importance for the bladder responses to BCG. Overall, the inflammation induced by BCG was higher than LPS or TNF-α treatment but the major difference observed was the unique granuloma formation in response to BCG. Among the cytokines measured, this study highlighted the importance of IL-1β, IL-2, IL-3, IL-4, IL-6, IL-10, IL-17, GM-CSF, KC, and Rantes as discriminators between generalized inflammation and BCG-specific inflammatory responses. CHIP/Q-PCR indicates that acute BCG instillation induced an up-regulation of IL-17A, IL-17B, and IL-17RA, whereas chronic BCG induced IL-17B, IL-17RA, and IL-17RB.

Conclusion

To the best of our knowledge, the present work is the first to report that BCG induces an increase in the IL-17 family genes. In addition, BCG induces a unique type of persisting bladder inflammation different from TNF-α, LPS, and, most likely, other classical pro-inflammatory stimuli.

BCG dose reduction by decreasing the instillation frequency: effects on local Th1/Th2 cytokine responses in a mouse model

OBJECTIVES

Based on the requirement of a Th1 immune response for clinical efficacy, and incited by the arbitrary induction scheme, frequent side effects and the empirical approach in improving BCG immunotherapy for superficial bladder cancer, an alternative intravesical BCG treatment schedule for dose reduction was investigated without compromising Th1 cytokine induction in the bladder in a mouse model.

METHODS

Mice were submitted to 6 weekly BCG instillations and treatment schedules omitting intermediate instillations during this standard scheme. Th1 (IFN-gamma, IL-2, IL-12p40), and Th2 (IL-10, IL-4) cytokine responses in individual mouse bladders were measured by a semiquantitative RT-PCR based method.

RESULTS

A schedule of only two BCG instillations, administered in week 1 and week 6, resulted in induction of at least the same levels of IFN-gamma, IL-2 and IL-12p40 Th1 cytokine mRNA compared to 6 weekly instillations, whereas significantly lower levels of Th2 cytokines IL-10 and IL-4 mRNA were observed.

CONCLUSIONS

During the 6-week period the intermediate weekly BCG instillations 2, 3, 4, and 5 do not contribute to Th1 cytokine upregulation in the bladder, provided that the BCG dose is sufficient. Whether such a reduced BCG frequency schedule has immune stimulating capacity and therapeutic efficacy associated with less side effects in patients remains to be investigated.

Immunostimulatory CpG oligonucleotides reduce tumor burden after intravesical administration in an orthotopic murine bladder cancer model

Bacillus Calmette-Guérin is established in the prophylaxis of recurrent intermediate and high-risk superficial bladder cancer and induces an unspecific, Th1-biased local immune response. Small CpG oligonucleotides (CpG ODN) containing a central unmethylated CpG motif are able to mimic the immunostimulatory activity of bacterial DNA. The purpose of the present study was to evaluate the antineoplastic properties of intravesically administered CpG ODN in an orthotopic murine bladder cancer model. MB49 tumor cell suspension was instilled transurethrally in female C57/BL6 mice on day 0. Mice were divided in three groups of 12 animals. Four mice in each group received either stimulative CpG ODN, non-stimulative GpC ODN or PBS intravesically: group I on day 3, group II on day 5, group III on day 7. After sacrifice 7 days after treatment, bladders were removed and histological examinations were performed. Single instillation of CpG ODN revealed antineoplastic effects in every group demonstrated by significantly lower bladder weight compared with non-stimulative GpC ODN- and PBS-treated mice. Histological examination showed extensive infiltration of macrophages and lymphocytes in CpG ODN-treated mice, whereas PBS- and GpC ODN-treated mice showed solid tumor growth with only few leucocytes. Intravesically applied immunostimulative DNA demonstrated antitumoral activity in an orthotopic murine bladder cancer model. A single instillation seems to be sufficient to reduce tumor load.

Role of urothelial cells in BCG immunotherapy for superficial bladder cancer

Intravesical instillation of Bacillus Calmette-Guérin (BCG) is used for the treatment of superficial bladder cancer, both to reduce the recurrence rate of bladder tumour and to diminish the risk of progression. Since its first therapeutic application in 1976, major research efforts have been directed to decipher the exact mechanism of action of the BCG-associated antitumour effect. Bacillus Calmette-Guérin causes an extensive local inflammatory reaction in the bladder wall. Of this, the massive appearance of cytokines in the urine of BCG-treated patients stands out. Activated lymphocytes and macrophages are the most likely sources of these cytokines, but at present other cellular sources such as urothelial tumour cells cannot be ruled out. Bacillus Calmette-Guérin is internalised and processed both by professional antigen-presenting cells and urothelial tumour cells, resulting in an altered gene expression of these cells that accumulates in the presentation of BCG antigens and secretion of particular cytokines.

Immunotherapy of Experimental Bladder Cancer with Recombinant BCG Expressing Interferon-γ

One of the most potent immunotherapies presently used is the application of Bacillus Calmette Guérin (BCG) to prevent recurrences of superficial bladder cancer. Despite its successful use, nonresponders and certain side effects remain a major obstacle. Therefore, current studies aim at developing recombinant BCG (rBCG) strains to further improve the effectiveness of the therapy. In BCG-treated patients a strong local induction of Th1-like cytokines was observed. For this reason rBCG-strains secreting Th1-like cytokines might be potentially useful agents to improve this type of immunotherapy. Because we previously demonstrated the essential role of IFNgamma in BCG-induced antitumor responses, in this study a rBCG strain secreting murine IFNgamma (rBCG-IFNgamma) was generated and tested for its immunostimulatory capacity in several in vitro and in vivo test systems. In vitro rBCG-IFNgamma specifically up-regulated expression of MHC class I molecules on a murine bladder cancer cell line (MB49), compared to the rBCG control strain (transfected with an empty vector). In a murine model of experimental bladder cancer, intravesical instillation of rBCG-IFNgamma resulted in an enhanced recruitment of CD4+ T-cells into the bladder and further induced the local expression of IL-2 and IL-4 cytokines (mRNA) compared to control rBCG. With a low-dose treatment regimen for murine orthotopic bladder cancer, rBCG-IFNgamma significantly prolonged survival, whereas the therapeutic effect of wild-type control BCG did not reach statistical significance. We conclude that this recombinant BCG strain has enhanced immunostimulatory potential and might offer new opportunities in the treatment of bladder cancer.