Macrophages directly kill bladder cancer cells through TNF signaling as an early response to BCG therapy.

The Bacillus Calmette-Guérin (BCG) vaccine is the oldest cancer immunotherapeutic agent in use. Despite its effectiveness, its initial mechanisms of action remain largely unknown. Here, we elucidate the earliest cellular mechanisms involved in BCG-induced tumor clearance. We developed a fast preclinical in vivo assay to visualize in real time and at single-cell resolution the initial interactions among bladder cancer cells, BCG and innate immunity using the zebrafish xenograft model. We show that BCG induced the recruitment and polarization of macrophages towards a pro-inflammatory phenotype, accompanied by induction of the inflammatory cytokines tnfa, il1b and il6 in the tumor microenvironment. Macrophages directly induced apoptosis of human cancer cells through zebrafish TNF signaling. Macrophages were crucial for this response as their depletion completely abrogated the BCG-induced phenotype. Contrary to the general concept that macrophage anti-tumoral activities mostly rely on stimulating an effective adaptive response, we demonstrate that macrophages alone can induce tumor apoptosis and clearance. Thus, our results revealed an additional step to the BCG-induced tumor immunity model, while providing proof-of-concept experiments demonstrating the potential of this unique model to test innate immunomodulators.

Lycopene alleviates BCG-induced depressive phenotypes in mice by disrupting 5-HT3 receptor - IDO1 interplay in the brain.

The 5-HT3 receptor and indoleamine 2,3-dioxygenase 1 (IDO1) enzyme play a crucial role in the pathogenesis of depression as their activation reduces serotonin contents in the brain. Since molecular docking analysis revealed lycopene as a potent 5-HT3 receptor antagonist and IDO1 inhibitor, we hypothesized that lycopene might disrupt the interplay between the 5-HT3 receptor and IDO1 to mitigate depression. In mice, the depression-like phenotypes were induced by inoculating Bacillus Calmette-Guerin (BCG). Lycopene (intraperitoneal; i.p.) was administered alone or in combination with 5-HT3 receptor antagonist ondansetron (i.p.) or IDO1 inhibitor minocycline (i.p.), and the behavioral screening was performed by the sucrose preference test, open field test, tail suspension test, and splash test which are based on the different principles. Further, the brains were subjected to the biochemical analysis of serotonin and its precursor tryptophan by the HPLC. The results showed depression-like behavior in BCG-inoculated mice, which was reversed by lycopene administration. Moreover, prior treatment with ondansetron or minocycline potentiated the antidepressant action of lycopene. Minocycline pretreatment also enhanced the antidepressant effect of ondansetron indicating the regulation of IDO1 activity by 5-HT3 receptor-triggered signaling. Biochemical analysis of brain samples revealed a drastic reduction in the levels of tryptophan and serotonin in depressed animals, which were restored following treatment with lycopene and its combination with ondansetron or minocycline. Taken together, the data from molecular docking, behavioral experiments, and biochemical estimation suggest that lycopene might block the 5-HT3 receptor and consequently inhibit the activity of IDO1 to ameliorate BCG-induced depression in mice.

Bergenin potentiates BCG efficacy by enriching mycobacteria-specific adaptive memory responses via the Akt-Foxo-Stat4 axis.

The extensive inability of the BCG vaccine to produce long-term immune protection has not only accelerated the disease burden but also progressed towards the onset of drug resistance. In our previous study, we have reported the promising effects of Bergenin (Berg) in imparting significant protection as an adjunct immunomodulator against tuberculosis (TB). In congruence with our investigations, we delineated the impact of Berg on T cells, wherein it enhanced adaptive memory responses by modulating key transcription factors, STAT4 and Akt. We translated this finding into the vaccine model of TB and observed a notable reduction in the burden of Mycobacterium tuberculosis (M.tb) in BCG-Berg co-immunized mice as compared to BCG vaccination. Moreover, Berg, along with BCG, also aided in a heightened proinflammatory response milieu that corroborates the host protective immune response against TB. Furthermore, this response aligns with the escalated central and resident memory responses by modulating the Akt-Foxo-Stat4 axis, which plays a crucial role in enhancing the vaccine efficacy of BCG. These findings showcase the utilization of immunomodulator Berg as an immunoprophylactic agent to upgrade immunological memory, making it a more effective defender against TB.

Optimizing outcomes for high-risk, non-muscle-invasive bladder cancer: The evolving role of PD-(L)1 inhibition.

Transurethral resection of bladder tumor followed by intravesical Bacillus Calmette-Guérin (BCG) is the standard of care in high-risk, non-muscle-invasive bladder cancer (NMIBC). Although many patients respond, recurrence and progression are common. In addition, patients may be unable to receive induction + maintenance due to intolerance or supply issues. Therefore, alternative treatment options are urgently required. Programmed cell death (ligand) 1 (PD-[L]1) inhibitors show clinical benefit in phase 1/2 trials in BCG-unresponsive NMIBC patients. This review presents the status of PD-(L)1 inhibition in high-risk NMIBC and discusses future directions. PubMed and Google scholar were searched for articles relating to NMIBC immunotherapy and ClinicalTrials.gov for planned and ongoing clinical trials. Preclinical and early clinical studies show that BCG upregulates PD-L1 expression in bladder cancer cells and, when combined with a PD-(L)1 inhibitor, a potent antitumor response is activated. Based on this mechanism, several PD-(L)1 inhibitors are in phase 3 trials in BCG-naïve, high-risk NMIBC in combination with BCG. Whereas PD-(L)1 inhibitors are well characterized in patients with advanced malignancies, the impact of immune-related adverse events (irAE) on the benefit/risk ratio in NMIBC should be determined. Alternative routes to intravenous administration, like subcutaneous and intravesical administration, may facilitate adherence and access. The outcomes of combination of PD-(L)1 inhibitors and BCG in NMIBC are highly anticipated. There will be a need to address treatment resources, optimal management of irAEs and education and training related to use of this therapy in clinical practice.

Endoplasmic Reticulum Stress Mediated NLRP3 Inflammasome Activation and Pyroptosis in THP-1 Macrophages Infected with Bacillus Calmette-Guérin.

Tuberculosis (TB) is a zoonotic infectious disease caused by Mycobacterium tuberculosis (Mtb). Mtb is a typical intracellular parasite, and macrophages are its main host cells. NLRP3 inflammasome-mediated pyroptosis is a form of programmed cell death implicated in the clearance of pathogenic infections. The bidirectional regulatory effect of endoplasmic reticulum stress (ERS) plays a crucial role in determining cell survival and death. Whether ERS is involved in macrophage pyroptosis with Mtb infection remains unclear. This article aims to explore the regulation of the NLRP3 inflammasome and pyroptosis by ERS in THP-1 macrophages infected with Mycobacterium bovis Bacillus Calmette-Guérin (BCG). The results showed that BCG infection induced THP-1 macrophage ERS, NLRP3 inflammasome activation and pyroptosis, which was inhibited by ERS inhibitor TUDCA. NLRP3 inhibitor MCC950 inhibited THP-1 macrophage NLRP3 inflammasome activation and pyroptosis caused by BCG infection. Compared with specific Caspase-1 inhibitor VX-765, pan-Caspase inhibitor Z-VAD-FMK showed a more significant inhibitory effect on BCG infection-induced pyroptosis of THP-1 macrophages. Taken together, this study demonstrates that ERS mediated NLRP3 inflammasome activation and pyroptosis after BCG infection of THP-1 macrophages, and that BCG infection of THP-1 macrophages induces pyroptosis through canonical and noncanonical pathways.

Efficacy of recombinant Bacillus Calmette-Guérin containing dltA in in vivo three-dimensional bio-printed bladder cancer-on-a-chip and ex vivo orthotopic mouse model.

PURPOSE: We investigated the efficacy and optimal dosage of recombinant Bacillus Calmette-Guérin-dltA (rBCG-dltA) in a high-throughput 3D bio-printed bladder cancer-on-a-chip (BCOC) and orthotopic bladder cancer mouse model. MATERIALS AND METHODS: We fabricated high-throughput BCOC with microfluidic systems, enabling efficient drug screening. The efficacy of rBCG-dltA was evaluated using BCOC by the cell viability assay, monocyte migration assay, and measuring cytokine levels. The anti-tumor effect was compared using the orthotopic bladder cancer mouse model. RESULTS: The cell proliferation rates of T24 and 253J bladder cancer cell lines (mean±standard error) were measured at three days after treatment. In T24 cell line, there was significantly decreased T24 cells compared to control at rBCG 1 multiplicity of infection (MOI) and 10 MOI (30 MOI: 63.1±6.4, 10 MOI: 47.4±5.2, 1 MOI: 50.5±7.5, control: 100.0±14.5, p<0.05). In 253J cell line, a statistically significant decrease in 253J cell count compared to control and mock BCG 30 MOI (30 MOI: 11.2±1.3, 10 MOI: 22.5±2.3, 1 MOI: 39.4±4.7, Mock: 54.9±10.8, control: 100.0±5.6, p<0.05). The migration rates of THP-1 cells showed increased patterns after rBCG-dltA treatment in BCOC. The concentration of tumor necrosis factor-α and interleukin-6 after rBCG-dltA 30 MOI treatment was higher than control in T24 and 253J cell line. CONCLUSIONS: In conclusion, rBCG-dltA has the potential to have better anti-tumor activity and immunomodulatory effects than BCG. Furthermore, high-throughput BCOCs have potential to reflect the bladder cancer microenvironment.

[Levofloxacin combined with cellulase can eradicate bacille Calmette-Guerin biofilm infection].

OBJECTIVE: To investigate the inhibitory effects of levofloxacin (LEV) combined with cellulase against bacille CalmetteGuerin (BCG) biofilms in vitro. METHODS: The mature growth cycle of BCG biofilms was determined using the XTT method and crystal violet staining. BCG planktonic bacteria and BCG biofilms were treated with different concentrations of LEV and cellulose alone or jointly, and the changes in biofilm biomass were quantified with crystal violet staining. The mature BCG biofilm was then treated with cellulase alone for 24 h, and after staining with SYTO 9 and Calcofluor White Stain, the number of viable bacteria and the change in cellulose content in the biofilm were observed with confocal laser scanning microscopy. The structural changes of the treated biofilm were observed under scanning electron microscopy. RESULTS: The MIC, MBC and MBEC values of LEV determined by broth microdilution method were 4 µg/mL, 8 µg/mL and 1024 µg/mL, respectively. The combined treatment with 1/4×MIC LEV and 2.56, 5.12 or 10.24 U/mL cellulase resulted in a significant reduction in biofilm biomass (P < 0.001). Cellulase treatments at the concentrations of 10.24, 5.12 and 2.56 U/mL all produced significant dispersion effects on mature BCG biofilms (P < 0.001). CONCLUSION: LEV combined with cellulose can effectively eradicate BCG biofilm infections, suggesting the potential of glycoside hydrolase therapy for improving the efficacy of antibiotics against biofilmassociated infections caused by Mycobacterium tuberculosis.

Novel Zebrafish Patient-Derived Tumor Xenograft Methodology for Evaluating Efficacy of Immune-Stimulating BCG Therapy in Urinary Bladder Cancer.

BACKGROUND: Bacillus Calmette-Guérin (BCG) immunotherapy is the standard-of-care adjuvant therapy for non-muscle-invasive bladder cancer in patients at considerable risk of disease recurrence. Although its exact mechanism of action is unknown, BCG significantly reduces this risk in responding patients but is mainly associated with toxic side-effects in those facing treatment resistance. Methods that allow the identification of BCG responders are, therefore, urgently needed. METHODS: Fluorescently labelled UM-UC-3 cells and dissociated patient tumor samples were used to establish zebrafish tumor xenograft (ZTX) models. Changes in the relative primary tumor size and cell dissemination to the tail were evaluated via fluorescence microscopy at three days post-implantation. The data were compared to the treatment outcomes of the corresponding patients. Toxicity was evaluated based on gross morphological evaluation of the treated zebrafish larvae. RESULTS: BCG-induced toxicity was avoided by removing the water-soluble fraction of the BCG formulation prior to use. BCG treatment via co-injection with the tumor cells resulted in significant and dose-dependent primary tumor size regression. Heat-inactivation of BCG decreased this effect, while intravenous BCG injections were ineffective. ZTX models were successfully established for six of six patients based on TUR-B biopsies. In two of these models, significant tumor regression was observed, which, in both cases, corresponded to the treatment response in the patients. CONCLUSIONS: The observed BCG-related anti-tumor effect indicates that ZTX models might predict the BCG response and thereby improve treatment planning. More experiments and clinical studies are needed, however, to elucidate the BCG mechanism and estimate the predictive value.

Oral Bacille Calmette-Guérin (BCG) vaccination induces long-term potentiation of memory immune response to Ovalbumin airway challenge in mice.

The Bacille Calmette-Guérin (BCG) is a potent immunomodulator. It was initially used by oral administration, but it is mostly used subcutaneously nowadays. This study shows that oral BCG vaccination modifies the immune response to a second non-related antigen (Ovalbumin) systemic immunization. Airway Ovalbumin challenge six months after the systemic intraperitoneal immunization resulted in a potent γδ+ T cell response in the lungs biased to IFN-γ and IL-17 production ex vivo and a mixed TH1, TH2, and TH17 T cells upon further stimulation with anti-CD3 mAb in vitro. Higher percentages of CD4+ T cells accompanied the augmented T cell response in oral BCG vaccinated mice. Also, the proportion of Foxp3+ Tregs was diminished compared to PBS-gavaged and OVA-immunized mice. The anti-OVA-specific antibody response was also influenced by oral exposure to BCG so that these mice produced more IgG2a and less IgE detected in the sera. These results suggest that oral BCG vaccination can modify future immune responses to vaccines and improve immunity to pathogen infections, especially in the mucosal interfaces.

Murine RAW Macrophages Are a Suitable Model to Study the CD3 Signaling in Myeloid Cells.

In recent years, a growing body of evidence has shown the presence of a subpopulation of macrophages that express CD3, especially in the context of mycobacterial infections. Despite these findings, the function of these cells has been poorly understood. Furthermore, the low frequency of CD3+ macrophages in humans limits the study of this subpopulation. This work aimed to evaluate the expression of CD3 in a murine macrophage cell line and its potential for the study of CD3 signaling. The murine macrophage cell line RAW was used to evaluate CD3 expression at the transcriptional and protein levels and the effect of in vitro infection with the Mycobacterium bovis Bacillus Calmette-Guérin (BCG) on these. Our data showed that RAW macrophages express CD3, both the ε and ζ chains, and it is further increased at the transcriptional level after BCG infection. Furthermore, our data suggest that CD3 can be found on the cell surface and intracellularly. However, this molecule is internalized constantly, mainly after activation with anti-CD3 stimulus, but interestingly, it is stably maintained at the transcriptional level. Finally, signaling proteins such as NFAT1, c-Jun, and IKK-α are highly expressed in RAW macrophages. They may play a role in the CD3-controlled signaling pathway to deliver inflammatory cytokines such as TNF and IL-6. Our study provides evidence to support that RAW cells are a suitable model to study the function and signaling of the CD3 complex in myeloid cells.

Effects of dietary supplementation of different levels of vitamin B12 on the liver metabolism of laying hens.

BACKGROUND: Vitamin B12 plays an important role in lipid, protein, carbohydrate and nucleic acid metabolism. We investigated the effect of supplementing layers' diets with different vitamin B12 levels on liver metabolism using a liquid chromatography-mass spectrometry-based metabolomic approach to observe and analyse wide-target metabolomics in the liver. RESULTS: We assigned hens to three groups, namely blank control group without vitamin B12 diet (BCG), normal control group with 25 µg kg-1 vitamin B12 (NCG) and vitamin B12 supplement group I with 100 µg kg-1 vitamin (VBSG I). The VBSG I group layers had higher (P < 0.05) vitamin B12 concentration than those from other groups. The egg yolk vitamin B12 concentration increased (P < 0.01) with the increasing vitamin B12 dietary supplemental level. Between the NCG versus BCG, VBSG I versus BCG, and VBSG I versus NCG groups, 11, 20 and 11 metabolites were significantly changed, respectively. The KEGG pathway of vitamin B6 metabolism was significantly impacted in the NCG layers than those from BCG; seven and five pathways were significantly impacted in the VBSG I layers compared with those from BCG and NCG, including pyrimidine metabolism, vitamin B6 metabolism, glycerophospholipid metabolism, etc. CONCLUSION: We concluded that 25 µg kg-1 vitamin B12 supplementation in corn-soybean meal-based layer diet increased the egg yolk vitamin B12 concentration and impacted the vitamin B6 metabolic pathway, and 100 µg kg-1 of it increased the egg yolk and liver vitamin B12 concentrations and impacted vitamin B6 , lipid, nucleic acid and amino acid metabolic pathways. © 2022 Society of Chemical Industry.

OncoTherad® (MRB-CFI-1) nano-immunotherapy reduced tumoral progression in non-muscle invasive bladder cancer through activation of Toll-like signaling pathway.

The new modalities for treating patients with high-grade non-muscle invasive bladder cancer (HGNMIBC) for whom Bacillus Calmette-Guerin (BCG) has failed or is contraindicated are recently increasing due to the development of new drugs. Since NMIBC is sensitive to immunotherapy, Toll-like receptors (TLRs) agonist compounds may represent a potential antitumor therapeutic approach. Our research group developed a synthetic compound, with antitumor and immunological properties, called OncoTherad® (MRB-CFI-1). To evaluate the effects of OncoTherad® (MRB-CFI-1) and its compounds (P14-16 and CFI-1), thirty-six female C57Bl/6 J mice were divided into six groups (n = 6): Control, Cancer, Cancer + BCG (40 mg), Cancer + OncoTherad® (20 mg/mL), Cancer + P14-16 (20 mg/mL) and Cancer + CFI-1 (20 mg/mL). NMIBC was chemically induced (N-ethyl-N-nitrosourea 50 mg/mL) and the treatments were followed for six weeks. The bladder was collected and routinely processed for immunohistochemical analyses of the Toll-Like receptors signaling pathway (TLR2, TLR4, MyD88, IRF-3, IKK-α, NF-kB, TNF-α, TRIF, IFN-γ, IL-6). The results obtained showed that the tumor progression was 100 % reduced on OncoTherad® (MRB-CFI-1) treated animals. Immunohistochemical analysis demonstrated that while the conventional BCG treatment stimulated the canonic pathway, OncoTherad® (MRB-CFI-1) stimulated the non-canonical pathway (increasing expression of TLR4, TRIF, IRF, and IFNγ). OncoTherad® (MRB-CFI-1) could be considered a promising therapy in the treatment of NMIBC.

Pharmacologic Activation of STING in the Bladder Induces Potent Antitumor Immunity in Non-Muscle Invasive Murine Bladder Cancer.

Stimulator of interferon genes (STING) is an innate immune receptor activated by natural or synthetic agonists to elicit antitumoral immune response via type I IFNs and other inflammatory cytokines. Bacillus Calmette-Guerin (BCG) is the standard of care as intravesical therapy for patients with high-risk non-muscle invasive bladder cancer (NMIBC). There are limited options available for patients with NMIBC who developed BCG unresponsiveness. In this study, we characterized in vitro and in vivo antitumor effects of E7766, a macrocyle-bridged STING agonist, via intravesical instillation in two syngeneic orthotopic murine NMIBC tumor models resistant to therapeutic doses of BCG and anti-PD-1 agents. E7766 bound to recombinant STING protein with a Kd value of 40 nmol/L and induced IFNß expression in primary human peripheral blood mononuclear cells harboring any of seven major STING genotypes with EC50 values of 0.15 to 0.79 µmol/L. Intravesical E7766 was efficacious in both NMIBC models with induction of effective immunologic memory in the treated animals. Pharmacologic activation of the STING pathway in the bladder resulted in IFN pathway activation, infiltration of T cells and natural killer (NK) cells, dendritic cell activation, and antigen presentation in bladder epithelium, leading to the antitumor activity and immunity. In addition, measurements of the pharmacodynamic markers, Ifnß1 and CXCL10, in bladder, urine, and plasma, and of STING pathway intactness in cancer cells, supported this mode of action. Taken together, our studies reveal an antitumor immune effect of pharmacologic activation of the STING pathway in bladder epithelium and thus provide a rationale for subsequent clinical studies in patients with NMIBC.

Immunotherapeutic effects of recombinant Bacillus Calmette-Guérin containing sic gene in ex vivo and in vivo bladder cancer models.

PURPOSE: The recombinant Bacillus Calmette-Guérin (BCG) containing the streptococcal inhibitor of the complement gene (rBCG-sic) may be more resistant to antimicrobial peptides and improve internalization; therefore, it can enhance the immunotherapeutic effect of the BCG. Here we determined the optimal dose of rBCG-sic and compared its effectiveness with that of BCG. MATERIALS AND METHODS: We fabricated a high-throughput 3D-bioprinted bladder cancer-on-a-chip (BCOC) and used it to evaluate the effectiveness of the rBCG-sic in terms of cell viability, cell migration, and cytokine concentrations. Using an orthotopic mouse model, we evaluated its anticancer effect and toxicity via bioluminescence imaging. RESULTS: T24 cell viability was decreased after treatment with rBCG-sic 30 multiplicities of infection (MOI) versus the same dosage of mock BCG (42.8%±6.4% vs. 75.7%±6.6%, p<0.05). THP-1 cell migration was positively correlated with rBCG-sic concentration (2.42-fold at 30MOI, p<0.01). The interleukin-6 concentration of rBCG-sic 30MOI was significantly higher than that of mock BCG 30MOI (11.2±1.3 pg/mL vs. 6.7±0.6 pg/mL, p<0.05). In the orthotopic bladder cancer mouse model, lower tumor volume was observed in the rBCG-sic 30MOI group than in the BCG 30MOI group after 10 days of treatment (p<0.05). CONCLUSIONS: We concluded that rBCG-sic is a useful tool for overcoming BCG unresponsiveness in non-muscle invasive bladder cancer. Additionally, high-throughput BCOC with a microfluidic system can successfully reflect the bladder cancer microenvironment.

Evaluating the effects of Cyclosporine A immunosuppression on Mycobacterial infection by inhaling of Cyclosporine A administrated BALB/c mice with live Bacillus Calmette Guérin.

Cyclosporine A (CsA) is an immunosuppressive drug used in organ transplantation and treatment of autoimmune diseases. Effects of CsA on determining the direction of the immune response and pathogenesis of infections by altering immune responses particulary T cells functions have always been questionable. We evaluated the effect of different doses of CsA on course of infection in BALB/c mice infected with live Bacillus Calmette Guérin (BCG) (as an example of Mycobacterial infections). Four groups of mice (n = 5) receiving 5, 25, 125, and 0 mg/kg of CsA, three times a week, were infected with BCG aerosolly. Before BCG inhalation and 40-/60- days post-infection, cell proliferation and CD4+CD25+ cell percentage were evaluated in splenocytes of mice after culture and stimulation with PHA or BCG lysate. The histopathological alterations and bacterial burden were assessed in lung tissue. Cells showed a dose-dependent decrease in proliferation and the percentage of CD4+ CD25+ cells. After BCG infection, in presence of dose 125 mg/kg, there were some exceptions. The number of bacteria and histopathological lesions and inflammation in lung tissues increased in a dose-dependent manner. CsA immunosuppressed BCG infected mice can be used as a safe model for studying Mycobacterium species pathogenesis and related cellular immune responses.

Chidamide and mitomycin C exert synergistic cytotoxic effects against bladder cancer cells in vitro and suppress tumor growth in a rat bladder cancer model.

Intravesical instillation (IVI) of Bacillus Calmette-Guerin (BCG) can prevent bladder cancer recurrence, but this agent has been out of stock in recent years. IVI of other agents, like chidamide, a histone deacetylase (HDAC) inhibitor, may have the potential to exert a therapeutic effect against bladder cancer by modifying the gene expression profiles associated with histone modifications that occur during cancer tumorigenesis. Here, we investigated the in vitro therapeutic effect of chidamide and/or mitomycin C in bladder cancer cell lines and screened related molecular pathways using an antibody array. We also quantitatively analyzed the synergistic effect of IVI of chidamide and mitomycin C in vivo in an N-methyl-N-nitrosourea (MNU)-induced rat bladder cancer model. The synergistic cytotoxic effect of chidamide plus mitomycin C was confirmed in both T24 and UMUC3 cells, with significantly greater induction of apoptosis elicited with chidamide plus mitomycin C than with either drug alone. The antibody array identified the Axl signaling pathway as the key target of the synergistic effect. Expression of Axl and its related downstream molecules, including claspin and survivin, was significantly suppressed. In the rat bladder cancer model, IVI of chidamide plus mitomycin C reduced tumor burden (Ki67 index) to a greater extent than either drug alone. Our results suggest that chidamide and mitomycin act synergistically to reduce MNU-induced bladder cancer. These findings provide new insights into a new and potentially effective approach to treating bladder cancer.

Sequence similarity of HSP65 of Mycobacterium bovis BCG with SARS-CoV-2 spike and nuclear proteins: may it predict an antigen-dependent immune protection of BCG against COVID-19?

The Bacillus Calmette-Guérin (BCG) vaccine is known to have protective effects not only against tuberculosis but also against other unrelated infectious diseases caused by different pathogens. Several epidemiological studies have also documented the beneficial influence of BCG vaccine in reducing both susceptibility to and severity of SARS-CoV-2 infection. The protective, non-specific effects of BCG vaccination would be related to an antigen-independent enhancement of the innate immunity, termed trained immunity. However, the knowledge that heat shock protein (HSP)65 is the main antigen of Mycobacterium bovis BCG prompted us to verify whether sequence similarity existed between HSP65 and SARS-CoV-2 spike (S) and nuclear (N) proteins that could support an antigen-driven immune protection of BCG vaccine. The results of the in silico investigation showed an extensive sequence similarity of HSP65 with both the viral proteins, especially SARS-CoV-2 S, that also involved the regions comprising immunodominant epitopes. The finding that the predicted B cell and CD4+ T cell epitopes of HSP65 shared strong similarity with the predicted B and T cell epitopes of both SARS-CoV-2 S and N would support the possibility of a cross-immune reaction of HSP65 of BCG with SARS-CoV-2.

Bacille Calmette-Guérin: An ophthalmic perspective.

Vaccines such as bacille Calmette-Guérin (BCG) are known for their heterologous effects mediated through a number of mechanisms, including trained immunity constituted by monocyte-macrophage based innate immunity. Other events such as direct hematogenous spread and induction of autoimmunity are also described. There has been a resurgent interest in harnessing some of the benefits of trained immunity in the management of COVID-19, even as several specific vaccines have been approved. We summarize the current knowledge of ocular effects of BCG. Potential effect of granulomatous inflammation on angiotensin converting enzyme activity and accentuation of cytokine storm that may result in undesirable ocular and systemic effects are also discussed.

γδ T Cells Support Antigen-Specific αß T cell-Mediated Antitumor Responses during BCG Treatment for Bladder Cancer.

Bacillus Calmette-Guérin (BCG) is the most effective intravesical agent at reducing recurrence for patients with high-grade, non-muscle-invasive bladder cancer. Nevertheless, response to BCG is variable and strategies to boost BCG efficacy have not materialized. Prior work demonstrated a requirement for either conventional αß or nonconventional γδ T cells in mediating BCG treatment efficacy, yet the importance of T-cell antigen specificity for BCG's treatment effect is unclear. Here, we provide direct evidence to show that BCG increases the number of tumor antigen-specific αß T cells in patients with bladder cancer and protects mice from subsequent same-tumor challenge, supporting BCG induction of tumor-specific memory and protection. Adoptive T-cell transfers of antigen-specific αß T cells into immunodeficient mice challenged with syngeneic MB49 bladder tumors showed that both tumor and BCG antigen-specific αß T cells contributed to BCG efficacy. BCG-specific antitumor immunity, however, also required nonconventional γδ T cells. Prior work shows that the mTOR inhibitor rapamycin induces the proliferation and effector function of γδ T cells. Here, rapamycin increased BCG efficacy against both mouse and human bladder cancer in vivo in a γδ T cell-dependent manner. Thus, γδ T cells augment antitumor adaptive immune effects of BCG and support rapamycin as a promising approach to boost BCG efficacy in the treatment of non-muscle-invasive bladder cancer.

Cheap and Commonplace: Making the Case for BCG and γδ T Cells in COVID-19.

Antigen-specific vaccines developed for the COVID-19 pandemic demonstrate a remarkable achievement and are currently being used in high income countries with much success. However, new SARS-CoV-2 variants are threatening this success via mutations that lessen the efficacy of antigen-specific antibodies. One simple approach to assisting with this issue is focusing on strategies that build on the non-specific protection afforded by the innate immune response. The BCG vaccine has been shown to provide broad protection beyond tuberculosis disease, including against respiratory viruses, and ongoing studies are investigating its efficacy as a tool against SARS-CoV-2. Gamma delta (γδ) T cells, particularly the Vδ2 subtype, undergo rapid expansion after BCG vaccination due to MHC-independent mechanisms. Consequently, γδ T cells can produce diverse defenses against virally infected cells, including direct cytotoxicity, death receptor ligands, and pro-inflammatory cytokines. They can also assist in stimulating the adaptive immune system. BCG is affordable, commonplace and non-specific, and therefore could be a useful tool to initiate innate protection against new SARS-CoV-2 variants. However, considerations must also be made to BCG vaccine supply and the prioritization of countries where it is most needed to combat tuberculosis first and foremost.