Could sublingual vaccination be a viable option for the prevention of recurrent urinary tract infection in Canada? A systematic review of the current literature and plans for the future

MV140 Mucosal Vaccine Induces Targeted Immune Response for Enhanced Clearance of Uropathogenic E. coli in Experimental Urinary Tract Infection

MV140 is an inactivated whole-cell bacterial mucosal vaccine with proven clinical efficacy against recurrent urinary tract infections (UTIs). These infections are primarily caused by uropathogenic E. coli (UPEC) strains, which are unique in their virulence factors and remarkably diverse. MV140 contains a non-UPEC strain, suggesting that it may induce an immune response against different UPEC-induced UTIs in patients. To verify this, we experimentally evaluated the cellular and humoral responses to UTI89, a prototypical UPEC strain, in mice vaccinated with MV140, as well as the degree of protection achieved in a UPEC UTI89 model of acute cystitis. The results show that both cellular (Th1/Th17) and antibody (IgG/IgA) responses to UTI89 were induced in MV140-immunized mice. MV140 vaccination resulted in an early increased clearance of UTI89 viable bacteria in the bladder and urine following transurethral infection. This was accompanied by a highly significant increase in CD4+ T cells in the bladder and an increase in urinary neutrophils. Collectively, our results support that MV140 induces cross-reactive humoral and cellular immune responses and cross-protection against UPEC strains.

Secondary Analysis of Interstitial Cystitis/Bladder Pain Syndrome Patients Enrolled in a Recurrent Urinary Tract Infection Prevention Study Provides a Novel Paradigm for Etio-Pathogenesis and Practical Management of This Infection Phenotype

INTRODUCTION

A subset of interstitial cystitis/bladder pain syndrome (IC/BPS) patients experience recurrent urinary tract infection (rUTI) associated with symptom flares. Recurrent UTI subjects with associated IC/BPS were enrolled in the first North American early clinical experience trial evaluating a new sublingual UTI preventative vaccine, MV140. It has been shown that women with rUTI develop an imbalance in the T helper 1 and 2 (Th2 over-expression) in the bladder mucosa. Our hypothesis-generating secondary analysis will suggest that this infection subcategory of IC/BPS patients develop a similar imbalance of Th1-Th2 response type to bacteria present in their urinary microbiome, leading to a bladder hypersensitivity that responds to mucosal immune modulation.

METHODS

Female participants with ≥3 documented UTI/year underwent a 3-month vaccination treatment period with a 9-month efficacy period after completion of vaccine treatment (total 12 months). There were no exclusion criteria for subjects in relation to baseline urinary symptoms and/or discomfort/pain. Primary outcome was no UTI following vaccination. Secondary outcomes included change in UTI incidence, overall patient-reported subjective global assessment (SGA responder defined as moderately or markedly improved on 7-point scale), and safety.

RESULTS

Sixteen subjects with IC/BPS-related symptoms and rUTI (mean age 47; range 23-74 years; mean number of UTI episodes in previous year 6.1 +/- 4.2) were eligible to be included in the Health Canada-approved MV140 vaccine study for prevention of rUTI. All subjects completed the 3-month vaccination period. One subject was lost to follow-up after their 6-month visit. Six subjects were UTI-free, while all 16 subjects had a reduction in UTI episodes compared to the year pre-vaccination. The total post-vaccination reduction in UTI episodes compared to pre-vaccination was 80% (0.1 UTI/subject/month from 0.5 UTI/subject/month, respectively). At 12 months, 13 subjects (81%) were SGA responders (moderately or markedly improved), and the responders reported a reduction in IC/BPS symptoms, with 8 subjects reporting significant or almost complete resolution of their specific long-term bladder discomfort/pain and bothersome urinary frequency or urgency. Four subjects reported mild and self-limited adverse events during vaccination period, but none were related to MV140 vaccine.

CONCLUSION

Sublingual MV140 vaccine in IC/BPS patients with rUTI not only achieved UTI-free or reduced UTI incidence status but also, after approximately 9 months post vaccination, resolution of patients' long-term treatment-refractory IC/BPS symptoms. This suggests some cases of IC/BPS may be etiologically based on Th2-driven hypersensitivity to bacteria within or entering the urinary microbiome that responds to a vaccine whose mechanism of action is to normalize or balance the bladder Th1/Th2 mucosal immune system.

Reducing Recurrent Urinary Tract Infections in Women with MV140 Impacts Personal Burden of Disease: Secondary Analyses of a Randomized Placebo-controlled Efficacy Study

Background

Recurrent urinary tract infection (rUTI) remains a major health burden for women. A randomized, double-blind, placebo-controlled trial (RCT; NCT02543827) reported that female patients with rUTI receiving a sublingual vaccine, MV140, had a reduction in rUTI and increase in UTI-free rate compared with placebo.

Objective

To determine the impact of MV140 on the personal burden of disease in women with rUTI using secondary endpoint data from the pivotal RCT evaluating MV140.

Design setting and participants

In the primary RCT, female patients with rUTI enrolled in Spain and UK (from October 2015 to April 2019) were randomized to placebo (6 mo) or MV140 (3 or 6 mo), and followed for 12 mo. Individuals analyzed in this secondary analysis included those in the placebo and 3-mo (recommended dose) groups.

Intervention

A polybacterial sublingual vaccine, MV140 (four inactivated whole-cell bacteria-Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, and Enterococcus faecalis), or placebo.

Outcome measurements and statistical analysis

Symptom severity scoring, antibiotic use, safety, and multiple aspects of quality of life (QoL; Short-Form Questionnaire [SF-36]) were assessed.

Results and limitations

Compared with the placebo group (n = 76), the 3-mo vaccinated group (n = 74) experienced fewer overall UTI symptoms (mean symptom score 102.2 ± 222.9 vs 194.2 ± 178.8; p = 0.0002), fewer days on antibiotics (12.4 ± 17.7 vs 28.7 ± 25.2; p = 0.0001), and improved total, general, and physical SF-36 QoL improvement (differences in means for total SF-36 score 15.7; 95% confidence interval [CI] 8.80, 22.64; p < 0.0001), with only social function QoL showing no impact (4.07; 95% CI -4.93, 13.08; p = 0.3744).

Conclusions

Three months of MV140 is associated with a reduction of the personal burden of UTI by reducing overall UTI symptoms and antibiotic use, improving QoL in women with rUTI.

Patient summary

Three months of MV140 vaccine, which has previously been shown to reduce the risk of urinary tract infection safely, is associated with a reduction in the personal burden of disease.

Therapeutic strategies for uncomplicated cystitis in women

Uncomplicated cystitis is affecting many women of all ages and has a great impact on the quality of life, especially in women suffering from recurrent, uncomplicated cystitis. By far the most frequent uropathogen, E. coli, may have acquired increasing resistance against a variety of oral antibiotics, which may differ between countries and regions. Therefore, local resistance data are important to be considered. On the other hand, non-antibiotic therapy has also become an option which should be discussed and offered to the patient. In patients suffering from recurrent uncomplicated cystitis, individual risk factors and possible behavioral changes should first be taken into account. Non-antimicrobial prophylactic strategies shown to be successful in well-designed clinical studies are the next options. Long term antibiotic prophylaxis, however, should only be considered as a last option. For some of those patients self-diagnosis and self-treatment may be suitable, e.g. by using a recognized questionnaire.

Immunoactive Prophylaxis Protocol of Uncomplicated Recurrent Urinary Tract Infections in a Cohort of 1104 Women Treated with Uromune® Vaccine

BACKGROUND

A prospective, descriptive, and multicenter research that included 1104 women with three or more uncomplicated UTIs following immunoprophylaxis with Uromune® vaccine between 2011 and 2022 is presented.

METHODS

OBJECTIVE

to analyze the efficacy of Uromune® and perform a follow-up protocol.

VARIABLES

age; bacteria; number of UTIs at baseline and at 3, 6, and 12 months of follow-up; distribution according to age and months of the year; therapy with polybacterial vaccine or autovaccine. Efficacy was defined as 0-2 UTIs during follow-up. Patients were divided into Group 1, with 3-4 UTIs at baseline, and Group 2, with 5 or more.

RESULTS

Average age was 72. Escherichia coli represented 64.3% of infections. Overall efficacy was 91.7%, 82.3%, and 57.6% at 3, 6, and 12 months. Efficacy in patients treated with vaccines was 95.8%, 88.4%, and 56.1%, and with autovaccines it was 85.7%, 73.6%, and 60.2%. Results were statistically significant in relation to vaccines (p < 0.05). Group 1 represented 65.2% and Group 2 represented 34.8%. Group 1 had an efficacy of 97.7%, 91.1%, and 64.7% and Group 2 had an efficacy of 80.2%, 64.3%, and 40%. Results were statistically significant in Group 1 (p < 0.05).

CONCLUSIONS

Patients at baseline with less than five UTIs will have better result and would benefit from a prophylaxis protocol with Uromune®.

Outcomes of Bladder Washout for the Treatment of Recurrent Urinary Tract Infections After Renal Transplantation

Background Current literature suggests that anywhere from 2.9-27% of renal transplant recipients (RTR) will develop recurrent urinary tract infections (UTIs) (≥2 UTIs over six months or ≥3 UTIs over 12 months). Recurrent UTIs are of particular importance to RTR given its increased risk for allograft fibrosis and overall patient survival. Alternative solutions are needed for the management of recurrent UTIs, especially given the vulnerability of RTR to UTIs. We hypothesize that bladder washout (BW) reduces the incidence and recurrence of UTIs in RTR. Methods This is a retrospective study evaluating the utility of BW procedures on RTR diagnosed with recurrent UTIs between December 2013 and July 2021 at a single center. Results A total of 106 patients were included in the study with a total of 118 BW performed. 69% of patients were successfully treated with BW, meaning they no longer met the criteria for recurrent UTIs (<1 UTI) in the six-month post-BW period. The mean number of UTIs was 2.76 (range 2-7) before the BW and 1.16 (range 0-5) after the BW. On average, there were 1.60 fewer UTIs in the post-BW period compared to the pre-BW period (p<0.0001). There is no statistically significant difference in success rates stratified by bacterial class (p=1) or antimicrobial resistance class (p=0.6937). Conclusion BW decreased the incidence of UTIs in the six-month post-operative period as nearly 70% of patients did not have UTI recurrence. This data provides evidence that BW may have utility in transplant recipients with recurrent UTIs. We hope this will stimulate further prospective randomized studies in this area.

MV140 sublingual vaccine reduces recurrent urinary tract infection in women Results from the first North American clinical experience study

INTRODUCTION

This is the first North American clinical evidence for MV140, a novel bacterial sublingual vaccine, developed for prevention of recurrent urinary tract infection (UTI) in women.

METHODS

Female subjects with ≥3 documented UTIs/year underwent three-month vaccination treatment, nine-month efficacy period, and optional three-month followup (total 15 months). Primary outcome was no clinically diagnosed UTI following vaccination (UTI-free rate). Secondary outcomes included absolute, mean, and median overall reduction in UTI compared to pre-vaccination, quality of life, global response assessment, patient satisfaction, microbiology, and safety.

RESULTS

Sixty-seven subjects (mean age 56 years, range 18-80) were enrolled; 64 completed the vaccination period and at least one post-vaccination assessment. Prior to vaccination, subjects reported a mean 6.8 UTIs/year. The UTI-free rate for the nine-month efficacy period was 40.6%. Compared to the infection rate in the year prior to vaccination, the reduction was 75.3% for the nine-month efficacy period post-vaccination. At 12-month followup, 80.3% reported that they were moderately/markedly improved; 58.1% were mostly satisfied, pleased, or delighted, while mean quality of life score improved by 1.5 points. Fourteen of the adverse events in nine subjects were potentially related to the vaccine - all mild and resolved by three months. None of the 13 serious adverse events were related to vaccine.

CONCLUSIONS

This first-in-North-America, prospective case series with the sublingual vaccine, MV140, adds further clinical evidence to its safety and effectiveness in reducing recurrent UTIs in women.

Antibiotic resistance in patients with liver cirrhosis: Prevalence and current approach to tackle

Regardless of etiology, complications with bacterial infection in patients with cirrhosis are reported in the range of 25%-46% according to the most recent data. Due to frequent episodes of bacterial infection and repetitive antibiotic treatment, most often with broad-spectrum gram negative coverage, patients with cirrhosis are at increased risk of encountering multidrug resistant bacteria, and this raises concern. In such patients, extended-spectrum beta-lactamase and AmpC-producing Enterobacterales, methicillin- or vancomycin-resistant Staphylococcus aureus, vancomycin-resistant Enterococci, carbapenem-resistant Pseudomonas aeruginosa, and Acinetobacter baumannii, all of which are difficult to treat, are the most common. That is why novel approaches to the prophylaxis and treatment of bacterial infections to avoid antibiotic resistance have recently been developed. At the same time, our knowledge of resistance mechanisms is constantly updated. This review summarizes the current situation regarding the burden of antibiotic resistance, including the prevalence and mechanisms of intrinsic and acquired resistance in bacterial species that most frequently cause complications in patients with liver cirrhosis and recent developments on how to deal with multidrug resistant bacteria.

A practical guide on the non-antibiotic options available in the prevention of recurrent urinary tract infections in women

Urinary Tract infection (UTI) is one of the most common infections worldwide, patients present to multiple different specialities in the community, primary and secondary care. Antibiotics are considered standard first line therapy in the treatment of urinary tract infections, however there is an alarming rise in global antibiotic resistance rates, so much so that the World Health Organisation has labelled antibiotic resistance as one of the biggest challenges to public health in our lifetime, publishing a global action plan to tackle this challenge. As a result, there is an increasing need to discover non-antibiotic alternatives, recently a number of novel therapies have been introduced into clinical practice. These are divided into oral, topical, intravesical and immunomodulation therapies. The aim of this paper is to summarise the current non-antibiotic treatments as a practical guide to utilise in patient care.

Klebsiella pneumoniae: adaptive immune landscapes and vaccine horizons

Klebsiella pneumoniae is among the most common antibiotic-resistant pathogens causing nosocomial infections. Additionally, it is a leading cause of neonatal sepsis and childhood mortality across the globe. Despite its clinical importance, we are only beginning to understand how the mammalian adaptive immune system responds to this pathogen. Further, many studies investigating potential K. pneumoniae vaccine candidates or alternative therapies have been launched in recent years. Here, we review the current state of knowledge on the adaptive immune response to K. pneumoniae infections and progress towards developing vaccines and other therapies to combat these infections.

The Promising Potential of Reverse Vaccinology-Based Next-Generation Vaccine Development over Conventional Vaccines against Antibiotic-Resistant Bacteria

The clinical use of antibiotics has led to the emergence of multidrug-resistant (MDR) bacteria, leading to the current antibiotic resistance crisis. To address this issue, next-generation vaccines are being developed to prevent antimicrobial resistance caused by MDR bacteria. Traditional vaccine platforms, such as inactivated vaccines (IVs) and live attenuated vaccines (LAVs), were effective in preventing bacterial infections. However, they have shown reduced efficacy against emerging antibiotic-resistant bacteria, including MDR M. tuberculosis. Additionally, the large-scale production of LAVs and IVs requires the growth of live pathogenic microorganisms. A more promising approach for the accelerated development of vaccines against antibiotic-resistant bacteria involves the use of in silico immunoinformatics techniques and reverse vaccinology. The bioinformatics approach can identify highly conserved antigenic targets capable of providing broader protection against emerging drug-resistant bacteria. Multi-epitope vaccines, such as recombinant protein-, DNA-, or mRNA-based vaccines, which incorporate several antigenic targets, offer the potential for accelerated development timelines. This review evaluates the potential of next-generation vaccine development based on the reverse vaccinology approach and highlights the development of safe and immunogenic vaccines through relevant examples from successful preclinical and clinical studies.

Young Women's Attitudes and Behaviors in Treatment and Prevention of UTIs: Are Biomedical Students at an Advantage?

We wanted to investigate whether students who study within biomedical fields (i.e., medicine, pharmacy science) differ from those whose studies are not connected to the biomedical field in terms of their attitudes and behaviors related to urinary tract infections (UTIs). This was a cross-sectional survey-based study conducted among 392 female students, of whom 243 attended a biomedical school and 149 (38.0%) attended a non-biomedical school, using a previously published tool. The survey was distributed as an online link via student representatives at different faculties. Only 22 (5.6%) of women felt that they could not recognize a UTI. A greater proportion of biomedical students wiped front to back, while significantly more non-biomedical students chose cotton underwear and avoided daily sanitary pads compared to biomedical students. As many as 215 (54.8%) women stated that they used cranberry preparations. Biomedical students showed greater awareness about possible resistance to repeated treatment (p = 0.002) and greater knowledge of possible interactions of antibiotics (p < 0.001). This study reveals that young women are confident in recognizing an UTIs, are open to alternative treatments, and would consider UTI management in a pharmacy setting. However, it reveals that there might be gaps in their knowledge regarding antibiotic resistance risks, possible interactions, and efficacy of available preparations, as participants from the group of biomedical students showed greater knowledge and different behaviors.

An Effective Sublingual Vaccine, MV140, Safely Reduces Risk of Recurrent Urinary Tract Infection in Women

Uncomplicated recurrent urinary tract infections (rUTIs) in women are associated with episodic bothersome symptoms and have a significant impact on the mental and physical quality of life. Treatment with antibiotics (short- and long-term dosing) results in acute and chronic side effects and costs and promotes general antibiotic resistance. Improved nonantibiotic management of rUTI in women represents a true, unmet medical need. MV140 is a novel sublingual mucosal-based bacterial vaccine developed for the prevention of rUTI in women. Based on observational, prospective, and randomized placebo-controlled studies, MV140 has been shown to safely prevent (or reduce the risk of) UTIs, reduce antibiotic use, overall management costs, and patient burden while improving the overall quality of life in women suffering from rUTIs.

Sublingual MV140 for Prevention of Recurrent Urinary Tract Infections

BACKGROUND: Recurrent urinary tract infections (UTIs), which consist of three or more episodes in 1 year or two or more infections in 6 months, affect 5% to 10% of women. MV140, a sublingual preparation of whole-cell inactivated bacteria, has shown clinical benefit in observational studies. This trial examined treatment with MV140 to prevent recurrent UTI. METHODS: In this multicenter, randomized, double-blind, placebo-controlled, parallel-group 1-year trial, 240 women 18 to 75 years of age from Spain and the United Kingdom with recurrent UTI were allocated to receive MV140 for 3 or 6 months or placebo for 6 months in a 1:1:1 ratio. The primary end point was the number of UTIs in the 9-month study period after 3 months of intervention. Key secondary end points were the percentage of women who were UTI free over the above period, time to UTI onset, and health-related quality of life. RESULTS: The median (interquartile range) of UTI episodes was 3.0 (0.5 to 6.0) for placebo compared with 0.0 (0.0 to 1.0) in both groups receiving MV140 (P<0.001). Among women treated with placebo, 25% (95% confidence interval [CI], 15% to 35%) were free of UTIs compared with 56% (95% CI, 44% to 67%) and 58% (95% CI, 44% to 67%) of women who received 3 and 6 months of MV140 treatment, respectively. A total of 205 AEs in 101 participants were registered (81, 76, and 48 in the placebo, 3-month MV140, and 6-month MV140 groups, respectively). CONCLUSIONS: In this controlled trial of modest size and duration, MV140 showed promising clinical efficacy in reducing recurrent UTI in women suffering from this condition. Adverse effects were not clinically limiting. (Funded by Inmunotek S.L. and Syner-Med [Pharmaceutical Products] Ltd.; ClinicalTrials.gov number, NCT02543827.)

Cost-Effectiveness of a Sublingual Bacterial Vaccine for the Prophylaxis of Recurrent Urinary Tract Infections

<b><i>Introduction:</i></b> Recurrent urinary tract infections (rUTIs) affect 5–10% of women, resulting in an enormous healthcare and society burden. Uromune® is a polybacterial sublingual vaccine with an excellent clinical benefit in rUTI prophylaxis. This study assesses the impact of sublingual vaccination on healthcare resource use and expenditures associated with this pathology. <b><i>Methods:</i></b> A quasi-experimental, pretest-posttest, single center study including women with rUTI and vaccinated with Uromune® in real-life clinical practice was performed. Variables were the need of healthcare resources, collected prospectively during two follow-up years, and the rUTI-associated expenditure, calculated using the micro-costing methodology; these were compared before and after vaccination. <b><i>Results:</i></b> A total of 166 women {mean (standard deviation [SD]) urinary tract infection episodes/year 6.19 (2.15)} were included. After vaccination, annual consultations with a primary care physician (PCP) (43.9%), emergency room visits (71.8%), urinary analysis (90.0%), and ultrasound exams (35.6%) decreased compared to pre-vaccination (all <i>p</i> &#x3c; 0.001). Per patient consumption in antibiotics, PCP consultations, emergency room visits, and complementary exams significantly decreased (all <i>p</i> &#x3c; 0.02), resulting in a reduction in healthcare expenditure per patient/year from mean (SD) 1,001.1 (655.0) to 497.1 (444.4) EUR. <b><i>Conclusion:</i></b> Sublingual bacterial vaccination with Uromune® decreased healthcare resource use and associated expenditure in women with rUTI, representing an optimal strategy to reduce rUTI-associated healthcare and economic burden.

Recurrent Urinary Tract Infections and Asymptomatic Bacteriuria in Adults

Purpose of review

Our goal was to summarize recent evidence regarding recurrent urinary tract infections and asymptomatic bacteriuria in different adult populations.

Recent findings

Several research groups are focused on the description of resident bacterial flora in the bladder and urinary dysbiosis in the microbiome era. Even the definitions might change in light of these discoveries. However, the role of urinary microbiome and bacterial interference has still to be determined.

Summary

Systematic treatment of asymptomatic bacteriuria is not recommended and even classic indications such as asymptomatic bacteriuria in pregnant women are controversial. In fact, its treatment is associated with a higher probability of symptomatic UTI and a higher prevalence of antibiotic-resistant bacteria. Improving the diagnosis of asymptomatic bacteriuria and optimizing the management of recurrent urinary tract infections, especially through non-antibiotics measures, are needed in order to minimise antimicrobial resistance.

Sublingual Bacterial Vaccination Reduces Recurrent Infections in Patients With Autoimmune Diseases Under Immunosuppressant Treatment

Introduction

Conventional or biologic disease-modifying anti-rheumatic drugs (DMARDs) are the mainstay of treatment for systemic autoimmune disease (SAD). Infectious complications are a major concern in their use.

Objective

To evaluate the clinical benefit of sublingual mucosal polybacterial vaccines (MV130 and MV140), used to prevent recurrent respiratory and urinary tract infections, in patients with SAD and secondary recurrent infections following conventional or biologic DMARDs.

Methods

An observational study in SAD patients with recurrent respiratory tract infections (RRTI) and/or recurrent urinary tract infections (RUTI) was carried out. All patients underwent mucosal (sublingual) vaccination with MV130 for RRTI or with MV140 for RUTI daily for 3 months. Clinical evaluation was assessed during 12 months of follow-up after the first dose, i.e., 3 months under treatment and 9 months once discontinued, and compared with the previous year.

Results

Forty-one out of 55 patients completed 1-year follow-up. All patients were on either conventional or biologic DMARDs. A significant decrease in the frequency of RUTI (p<0.001), lower respiratory tract infections (LRTI) (p=0.009) and upper respiratory tract infections (URTI) (p=0.006) at 12-mo with respect to the previous year was observed. Antibiotic prescriptions and unscheduled medical visits decreased significantly (p<0.020) in all groups. Hospitalization rate also declined in patients with RRTI (p=0.019). The clinical benefit demonstrated was concomitant to a significant increase in both anti-S. pneumoniae IgA and IgG antibodies following MV130 vaccination.

Conclusions

Sublingual polybacterial vaccines prevent recurrent infections in patients with SAD under treatment with immunosuppressant therapies, supporting a broad non-specific anti-infectious effect in these patients.

Strategies to Tackle Antimicrobial Resistance: The Example of Escherichia coli and Pseudomonas aeruginosa

Traditional antimicrobial treatments consist of drugs which target different essential functions in pathogens. Nevertheless, bacteria continue to evolve new mechanisms to evade this drug-mediated killing with surprising speed on the deployment of each new drug and antibiotic worldwide, a phenomenon called antimicrobial resistance (AMR). Nowadays, AMR represents a critical health threat, for which new medical interventions are urgently needed. By 2050, it is estimated that the leading cause of death will be through untreatable AMR pathogens. Although antibiotics remain a first-line treatment, non-antibiotic therapies such as prophylactic vaccines and therapeutic monoclonal antibodies (mAbs) are increasingly interesting alternatives to limit the spread of such antibiotic resistant microorganisms. For the discovery of new vaccines and mAbs, the search for effective antigens that are able to raise protective immune responses is a challenging undertaking. In this context, outer membrane vesicles (OMV) represent a promising approach, as they recapitulate the complete antigen repertoire that occurs on the surface of Gram-negative bacteria. In this review, we present Escherichia coli and Pseudomonas aeruginosa as specific examples of key AMR threats caused by Gram-negative bacteria and we discuss the current status of mAbs and vaccine approaches under development as well as how knowledge on OMV could benefit antigen discovery strategies.

A Combination of Polybacterial MV140 and Candida albicans V132 as a Potential Novel Trained Immunity-Based Vaccine for Genitourinary Tract Infections

Recurrent urinary tract infections (RUTIs) and recurrent vulvovaginal candidiasis (RVVCs) represent major healthcare problems with high socio-economic impact worldwide. Antibiotic and antifungal prophylaxis remain the gold standard treatments for RUTIs and RVVCs, contributing to the massive rise of antimicrobial resistance, microbiota alterations and co-infections. Therefore, the development of novel vaccine strategies for these infections are sorely needed. The sublingual heat-inactivated polyvalent bacterial vaccine MV140 shows clinical efficacy for the prevention of RUTIs and promotes Th1/Th17 and IL-10 immune responses. V132 is a sublingual preparation of heat-inactivated Candida albicans developed against RVVCs. A vaccine formulation combining both MV140 and V132 might well represent a suitable approach for concomitant genitourinary tract infections (GUTIs), but detailed mechanistic preclinical studies are still needed. Herein, we showed that the combination of MV140 and V132 imprints human dendritic cells (DCs) with the capacity to polarize potent IFN-γ- and IL-17A-producing T cells and FOXP3+ regulatory T (Treg) cells. MV140/V132 activates mitogen-activated protein kinases (MAPK)-, nuclear factor-κB (NF-κB)- and mammalian target of rapamycin (mTOR)-mediated signaling pathways in human DCs. MV140/V132 also promotes metabolic and epigenetic reprogramming in human DCs, which are key molecular mechanisms involved in the induction of innate trained immunity. Splenocytes from mice sublingually immunized with MV140/V132 display enhanced proliferative responses of CD4+ T cells not only upon in vitro stimulation with the related antigens contained in the vaccine formulation but also upon stimulation with phytohaemagglutinin. Additionally, in vivo sublingual immunization with MV140/V132 induces the generation of IgG and IgA antibodies against all the components contained in the vaccine formulation. We uncover immunological mechanisms underlying the potential mode of action of a combination of MV140 and V132 as a novel promising trained immunity-based vaccine (TIbV) for GUTIs.