Daniel Arve Butler
Postdoctoral Scholar, Microbiology and Immunology
Honors & Awards
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Postdoctoral fellowship, School of Medicine Dean's Postdoctoral Fellowship (2023)
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Postdoctoral fellowship, Svenska sällskapet för medicinsk forskning (2022)
Professional Education
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Doctor of Philosophy, Lunds Universitet (2020)
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Ph.D, Lund University, Immunology and Microbiology (2020)
All Publications
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Phytotherapy (BNO 1045) of Acute Lower Uncomplicated Urinary Tract Infection in Women Normalizes Local Host Responses
UROLOGIA INTERNATIONALIS
2023: 1-7
Abstract
Acute lower uncomplicated urinary tract infection (uUTI) affects a large proportion of women. Increased antimicrobial resistance has created an urgent need for novel therapeutics and the phytotherapeutic drug BNO 1045 (Canephron® N) has previously been shown to be noninferior to standard antimicrobial stewardship. This sub-analysis from a randomized, double-blind, controlled phase III noninferiority clinical trial using BNO 1045 versus fosfomycin to treat uUTI aimed to determine how urine cytokine levels are altered by the two different treatments.Urine samples from a predefined subset of women diagnosed with uUTI (18-70 years) and treated with BNO 1045 (n = 58) or fosfomycin (n = 69) were analyzed for urine levels of IL-6 and IL-8, using analyte-to-creatinine ratios.BNO 1045 treatment showed similar effects to fosfomycin treatment in reducing both urine IL-6 and IL-8 levels. Mean IL-6 and IL-8 levels were markedly reduced in all patients regardless of treatment. BNO 1045 treatment decreased urine IL-8 significantly (p = 0.0142) and showed a trend toward reduction of urine IL-6 (p = 0.0551). Fosfomycin treatment reduced both IL-6 and IL-8 levels significantly (p = 0.0038, <0.0001 respectively).BNO 1045 is, in addition to reducing symptoms, comparable to fosfomycin treatment in reducing the local inflammatory response associated with uUTI.
View details for DOI 10.1159/000531206
View details for Web of Science ID 001044632900001
View details for PubMedID 37544300
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One species, different diseases: the unique molecular mechanisms that underlie the pathogenesis of typhoidal Salmonella infections.
Current opinion in microbiology
2023; 72: 102262
Abstract
Salmonella enterica is one of the most widespread bacterial pathogens found worldwide, resulting in approximately 100 million infections and over 200 000 deaths per year. Salmonella isolates, termed 'serovars', can largely be classified as either nontyphoidal or typhoidal Salmonella, which differ in regard to disease manifestation and host tropism. Nontyphoidal Salmonella causes gastroenteritis in many hosts, while typhoidal Salmonella is human-restricted and causes typhoid fever, a systemic disease with a mortality rate of up to 30% without treatment. There has been considerable interest in understanding how different Salmonella serovars cause different diseases, but the molecular details that underlie these infections have not yet been fully characterized, especially in the case of typhoidal Salmonella. In this review, we highlight the current state of research into understanding the pathogenesis of both nontyphoidal and typhoidal Salmonella, with a specific interest in serovar-specific traits that allow human-adapted strains of Salmonella to cause enteric fever. Overall, a more detailed molecular understanding of how different Salmonella isolates infect humans will provide critical insights into how we can eradicate these dangerous enteric pathogens.
View details for DOI 10.1016/j.mib.2022.102262
View details for PubMedID 36640585
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Immunomodulation therapy offers new molecular strategies to treat UTI
NATURE REVIEWS UROLOGY
2022; 19 (7): 419-437
Abstract
Innovative solutions are needed for the treatment of bacterial infections, and a range of antibacterial molecules have been explored as alternatives to antibiotics. A different approach is to investigate the immune system of the host for new ways of making the antibacterial defence more efficient. However, the immune system has a dual role as protector and cause of disease: in addition to being protective, increasing evidence shows that innate immune responses can become excessive and cause acute symptoms and tissue pathology during infection. This role of innate immunity in disease suggests that the immune system should be targeted therapeutically, to inhibit over-reactivity. The ultimate goal is to develop therapies that selectively attenuate destructive immune response cascades, while augmenting the protective antimicrobial defence but such treatment options have remained underexplored, owing to the molecular proximity of the protective and destructive effects of the immune response. The concept of innate immunomodulation therapy has been developed successfully in urinary tract infections, based on detailed studies of innate immune activation and disease pathogenesis. Effective, disease-specific, immunomodulatory strategies have been developed by targeting specific immune response regulators including key transcription factors. In acute pyelonephritis, targeting interferon regulatory factor 7 using small interfering RNA or treatment with antimicrobial peptide cathelicidin was protective and, in acute cystitis, targeting overactive effector molecules such as IL-1β, MMP7, COX2, cAMP and the pain-sensing receptor NK1R has been successful in vivo. Furthermore, other UTI treatment strategies, such as inhibiting bacterial adhesion and vaccination, have also shown promise.
View details for DOI 10.1038/s41585-022-00602-4
View details for Web of Science ID 000814480100001
View details for PubMedID 35732832
View details for PubMedCentralID PMC9214477
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Immunomodulation-A Molecular Solution to Treating Patients with Severe Bladder Pain Syndrome?
EUROPEAN UROLOGY OPEN SCIENCE
2021; 31: 49-58
Abstract
Patients with bladder pain syndrome experience debilitating pain and extreme frequency of urination. Numerous therapeutic approaches have been tested, but as the molecular basis of disease has remained unclear, specific therapies are not available.Recently, a systematic gene deletion strategy identified interleukin-1 (IL-1) hyperactivation as a cause of severe cystitis in a murine model. Treatment with an IL-1 receptor antagonist (IL-1RA) restored health in genetically susceptible mice, linking IL-1-dependent inflammation to pain and pathology in the bladder mucosa. The study objective was to investigate whether IL-1RA treatment might be beneficial in patients with bladder pain syndrome.Patients diagnosed with bladder pain syndrome were invited to participate and subjected to daily IL-1RA injections for 1 wk, followed by a treatment break. Patients with other urological disorders accompanied by pain were included as controls.When symptoms returned, treatment was resumed and responding patients were maintained on treatment long term, with individualized dosing regimens. Symptom scores were recorded and molecular effects were quantified by neuropeptide and gene expression analysis. DNA samples were subjected to exome genotyping.IL-1RA treatment reduced bladder pain and the frequency of urination in 13/17 patients (p < 0.001). Substance P levels in urine were lowered, and responders returned to a more normal lifestyle. Neuroinflammatory-dependent and IL-1-dependent gene networks were inhibited, as well as regulators of innate immunity. Genotyping revealed disease-associated IL1R1, NLRP3, and IL1RN DNA sequence variants in the responders. Controls did not benefit from IL-1RA treatment, except for one patent with cystitis cystica.In this clinical study, IL-1RA treatment is proposed to reduce chronic bladder pain, immediately and in the long term. Despite the limited number of study patients, the potent acute effect and lasting symptom relief indicate that this therapeutic approach may be worth exploring in controlled clinical trials.Treatment with an interleukin-1 (IL-1) receptor antagonist is proposed for treating bladder pain syndrome, as it can result in symptom relief and increase quality of life. Reduced neuroinflammation and IL-1 signaling provided molecular evidence of the treatment effects.
View details for DOI 10.1016/j.euros.2021.07.003
View details for Web of Science ID 000687321000010
View details for PubMedID 34467240
View details for PubMedCentralID PMC8385293
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Molecular determinants of disease severity in urinary tract infection
NATURE REVIEWS UROLOGY
2021; 18 (8): 468-486
Abstract
The most common and lethal bacterial pathogens have co-evolved with the host. Pathogens are the aggressors, and the host immune system is responsible for the defence. However, immune responses can also become destructive, and excessive innate immune activation is a major cause of infection-associated morbidity, exemplified by symptomatic urinary tract infections (UTIs), which are caused, in part, by excessive innate immune activation. Severe kidney infections (acute pyelonephritis) are a major cause of morbidity and mortality, and painful infections of the urinary bladder (acute cystitis) can become debilitating in susceptible patients. Disease severity is controlled at specific innate immune checkpoints, and a detailed understanding of their functions is crucial for strategies to counter microbial aggression with novel treatment and prevention measures. One approach is the use of bacterial molecules that reprogramme the innate immune system, accelerating or inhibiting disease processes. A very different outcome is asymptomatic bacteriuria, defined by low host immune responsiveness to bacteria with attenuated virulence. This observation provides the rationale for immunomodulation as a new therapeutic tool to deliberately modify host susceptibility, control the host response and avoid severe disease. The power of innate immunity as an arbitrator of health and disease is also highly relevant for emerging pathogens, including the current COVID-19 pandemic.
View details for DOI 10.1038/s41585-021-00477-x
View details for Web of Science ID 000661803300002
View details for PubMedID 34131331
View details for PubMedCentralID PMC8204302
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Bladder cancer therapy using a conformationally fluid tumoricidal peptide complex
NATURE COMMUNICATIONS
2021; 12 (1): 3427
Abstract
Partially unfolded alpha-lactalbumin forms the oleic acid complex HAMLET, with potent tumoricidal activity. Here we define a peptide-based molecular approach for targeting and killing tumor cells, and evidence of its clinical potential (ClinicalTrials.gov NCT03560479). A 39-residue alpha-helical peptide from alpha-lactalbumin is shown to gain lethality for tumor cells by forming oleic acid complexes (alpha1-oleate). Nuclear magnetic resonance measurements and computational simulations reveal a lipid core surrounded by conformationally fluid, alpha-helical peptide motifs. In a single center, placebo controlled, double blinded Phase I/II interventional clinical trial of non-muscle invasive bladder cancer, all primary end points of safety and efficacy of alpha1-oleate treatment are reached, as evaluated in an interim analysis. Intra-vesical instillations of alpha1-oleate triggers massive shedding of tumor cells and the tumor size is reduced but no drug-related side effects are detected (primary endpoints). Shed cells contain alpha1-oleate, treated tumors show evidence of apoptosis and the expression of cancer-related genes is inhibited (secondary endpoints). The results are especially encouraging for bladder cancer, where therapeutic failures and high recurrence rates create a great, unmet medical need.
View details for DOI 10.1038/s41467-021-23748-y
View details for Web of Science ID 000664803600010
View details for PubMedID 34103518
View details for PubMedCentralID PMC8187399
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Active bacterial modification of the host environment through RNA polymerase II inhibition
JOURNAL OF CLINICAL INVESTIGATION
2021; 131 (4)
Abstract
Unlike pathogens, which attack the host, commensal bacteria create a state of friendly coexistence. Here, we identified a mechanism of bacterial adaptation to the host niche, where they reside. Asymptomatic carrier strains were shown to inhibit RNA polymerase II (Pol II) in host cells by targeting Ser2 phosphorylation, a step required for productive mRNA elongation. Assisted by a rare, spontaneous loss-of-function mutant from a human carrier, the bacterial NlpD protein was identified as a Pol II inhibitor. After internalization by host cells, NlpD was shown to target constituents of the Pol II phosphorylation complex (RPB1 and PAF1C), attenuating host gene expression. Therapeutic efficacy of a recombinant NlpD protein was demonstrated in a urinary tract infection model, by reduced tissue pathology, accelerated bacterial clearance, and attenuated Pol II-dependent gene expression. The findings suggest an intriguing, evolutionarily conserved mechanism for bacterial modulation of host gene expression, with a remarkable therapeutic potential.
View details for DOI 10.1172/JCI140333
View details for Web of Science ID 000620153400001
View details for PubMedID 33320835
View details for PubMedCentralID PMC7880420
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A bacterial protease depletes c-MYC and increases survival in mouse models of bladder and colon cancer
NATURE BIOTECHNOLOGY
2021; 39 (6): 754-764
Abstract
Is the oncogene MYC upregulated or hyperactive? In the majority of human cancers, finding agents that target c-MYC has proved difficult. Here we report specific bacterial effector molecules that inhibit cellular MYC (c-MYC) in human cells. We show that uropathogenic Escherichia coli (UPEC) degrade the c-MYC protein and attenuate MYC expression in both human cells and animal tissues. c-MYC protein was rapidly degraded by both cell-free bacterial lysates and the purified bacterial protease Lon. In mice, intravesical or peroral delivery of Lon protease delayed tumor progression and increased survival in MYC-dependent bladder and colon cancer models, respectively. These results suggest that bacteria have evolved strategies to control c-MYC tissue levels in the host and that the Lon protease shows promise for therapeutic targeting of c-MYC in cancer.
View details for DOI 10.1038/s41587-020-00805-3
View details for Web of Science ID 000617109400002
View details for PubMedID 33574609
View details for PubMedCentralID 359676
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Bladder cancer therapy without toxicity-A dose-escalation study of alpha1-oleate
INTERNATIONAL JOURNAL OF CANCER
2020; 147 (9): 2479-2492
Abstract
Potent chemotherapeutic agents are required to counteract the aggressive behavior of cancer cells and patients often experience severe side effects, due to tissue toxicity. Our study addresses if a better balance between efficacy and toxicity can be attained using the tumoricidal complex alpha1-oleate, formed by a synthetic, alpha-helical peptide comprising the N-terminal 39 amino acids of alpha-lactalbumin and the fatty acid oleic acid. Bladder cancer was established, by intravesical instillation of MB49 cells on day 0 and the treatment group received five instillations of alpha1-oleate (1.7-17 mM) on days 3 to 11. A dose-dependent reduction in tumor size, bladder size and bladder weight was recorded in the alpha1-oleate treated group, compared to sham-treated mice. Tumor markers Ki-67, Cyclin D1 and VEGF were inhibited in a dose-dependent manner, as was the expression of cancer-related genes. Remarkably, toxicity for healthy tissue was not detected in alpha1-oleate-treated, tumor-bearing mice or healthy mice or rabbits, challenged with increasing doses of the active complex. The results define a dose-dependent therapeutic effect of alpha1-oleate in a murine bladder cancer model.
View details for DOI 10.1002/ijc.33019
View details for Web of Science ID 000531432200001
View details for PubMedID 32319672
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Fimbriae reprogram host gene expression - Divergent effects of P and type 1 fimbriae
PLOS PATHOGENS
2019; 15 (6): e1007671
Abstract
Pathogens rely on a complex virulence gene repertoire to successfully attack their hosts. We were therefore surprised to find that a single fimbrial gene reconstitution can return the virulence-attenuated commensal strain Escherichia coli 83972 to virulence, defined by a disease phenotype in human hosts. E. coli 83972pap stably reprogrammed host gene expression, by activating an acute pyelonephritis-associated, IRF7-dependent gene network. The PapG protein was internalized by human kidney cells and served as a transcriptional agonist of IRF-7, IFN-β and MYC, suggesting direct involvement of the fimbrial adhesin in this process. IRF-7 was further identified as a potent upstream regulator (-log (p-value) = 61), consistent with the effects in inoculated patients. In contrast, E. coli 83972fim transiently attenuated overall gene expression in human hosts, enhancing the effects of E. coli 83972. The inhibition of RNA processing and ribosomal assembly indicated a homeostatic rather than a pathogenic end-point. In parallel, the expression of specific ion channels and neuropeptide gene networks was transiently enhanced, in a FimH-dependent manner. The studies were performed to establish protective asymptomatic bacteriuria in human hosts and the reconstituted E. coli 83972 variants were developed to improve bacterial fitness for the human urinary tract. Unexpectedly, P fimbriae were able to drive a disease response, suggesting that like oncogene addiction in cancer, pathogens may be addicted to single super-virulence factors.
View details for DOI 10.1371/journal.ppat.1007671
View details for Web of Science ID 000479154700002
View details for PubMedID 31181116
View details for PubMedCentralID PMC6557620
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Neuroepithelial control of mucosal inflammation in acute cystitis
SCIENTIFIC REPORTS
2018; 8: 11015
Abstract
The nervous system is engaged by infection, indirectly through inflammatory cascades or directly, by bacterial attack on nerve cells. Here we identify a neuro-epithelial activation loop that participates in the control of mucosal inflammation and pain in acute cystitis. We show that infection activates Neurokinin-1 receptor (NK1R) and Substance P (SP) expression in nerve cells and bladder epithelial cells in vitro and in vivo in the urinary bladder mucosa. Specific innate immune response genes regulated this mucosal response, and single gene deletions resulted either in protection (Tlr4-/- and Il1b-/- mice) or in accentuated bladder pathology (Asc-/- and Nlrp3-/- mice), compared to controls. NK1R/SP expression was lower in Tlr4-/- and Il1b-/- mice than in C56BL/6WT controls but in Asc-/- and Nlrp3-/- mice, NK1R over-activation accompanied the exaggerated disease phenotype, due, in part to transcriptional de-repression of Tacr1. Pharmacologic NK1R inhibitors attenuated acute cystitis in susceptible mice, supporting a role in disease pathogenesis. Clinical relevance was suggested by elevated urine SP levels in patients with acute cystitis, compared to patients with asymptomatic bacteriuria identifying NK1R/SP as potential therapeutic targets. We propose that NK1R and SP influence the severity of acute cystitis through a neuro-epithelial activation loop that controls pain and mucosal inflammation.
View details for DOI 10.1038/s41598-018-28634-0
View details for Web of Science ID 000439278300050
View details for PubMedID 30030504
View details for PubMedCentralID PMC6054610
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Triggered Urine Interleukin-6 Correlates to Severity of Symptoms in Nonfebrile Lower Urinary Tract Infections
JOURNAL OF UROLOGY
2017; 198 (1): 107-114
Abstract
Objective diagnosis of symptomatic urinary tract infections in patients prone to asymptomatic bacteriuria is compromised by local host responses that are already present and the positive urine culture. We investigated interleukin-6 as a biomarker for nonfebrile urinary tract infection severity and diagnostic thresholds for interleukin-6 and 8, and neutrophils to differentiate between asymptomatic bacteriuria and urinary tract infection.Patients with residual urine and neurogenic bladders due to spinal lesions included in a long-term Escherichia coli 83972 asymptomatic bacteriuria inoculation trial were monitored for 2 years. Symptom scoring and urine sampling to estimate interleukin-6 and 8, and neutrophils were performed regularly monthly and at urinary tract infection episodes.Patients were followed in the complete study for a mean of 19 months (range 10 to 27) and those with asymptomatic bacteriuria with E. coli 83972 were followed a mean of 11 months (range 4 to 19). A total of 37 nonfebrile urinary tract infection episodes with complete data on interleukin-6 and 8, neutrophils and symptom scoring were documented. Interleukin-6 was the only marker that persistently increased during urinary tract infection compared to asymptomatic bacteriuria in pooled and paired intra-individual comparisons (p <0.05). Interleukin-6 above the threshold (greater than 25 ng/l) correlated to more severe urinary tract infection symptoms (p <0.05). The sensitivity and specificity of all biomarkers were poor/moderate when differentiating asymptomatic bacteriuria vs all urinary tract infection episodes. However, in urinary tract infections with worse symptoms interleukin-6 and neutrophils demonstrated equal good/excellent outcomes.Triggered interleukin-6 correlated to urinary tract infection symptom severity and demonstrated a promising differential diagnostic capacity to discriminate urinary tract infection from asymptomatic bacteriuria. Future studies should explore interleukin-6 as a biomarker of urinary tract infection severity and assess the treatment indication in nonfebrile urinary tract infections.
View details for DOI 10.1016/j.juro.2017.01.070
View details for Web of Science ID 000402985200042
View details for PubMedID 28161350
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Molecular Basis of Acute Cystitis Reveals Susceptibility Genes and Immunotherapeutic Targets
PLOS PATHOGENS
2016; 12 (10): e1005848
Abstract
Tissue damage is usually regarded as a necessary price to pay for successful elimination of pathogens by the innate immune defense. Yet, it is possible to distinguish protective from destructive effects of innate immune activation and selectively attenuate molecular nodes that create pathology. Here, we identify acute cystitis as an Interleukin-1 beta (IL-1β)-driven, hyper-inflammatory condition of the infected urinary bladder and IL-1 receptor blockade as a novel therapeutic strategy. Disease severity was controlled by the mechanism of IL-1β processing and mice with intact inflammasome function developed a moderate, self-limiting form of cystitis. The most severe form of acute cystitis was detected in mice lacking the inflammasome constituents ASC or NLRP-3. IL-1β processing was hyperactive in these mice, due to a new, non-canonical mechanism involving the matrix metalloproteinase 7- (MMP-7). ASC and NLRP-3 served as transcriptional repressors of MMP7 and as a result, Mmp7 was markedly overexpressed in the bladder epithelium of Asc-/- and Nlrp3-/- mice. The resulting IL-1β hyper-activation loop included a large number of IL-1β-dependent pro-inflammatory genes and the IL-1 receptor antagonist Anakinra inhibited their expression and rescued susceptible Asc-/- mice from bladder pathology. An MMP inhibitor had a similar therapeutic effect. Finally, elevated levels of IL-1β and MMP-7 were detected in patients with acute cystitis, suggesting a potential role as biomarkers and immunotherapeutic targets. The results reproduce important aspects of human acute cystitis in the murine model and provide a comprehensive molecular framework for the pathogenesis and immunotherapy of acute cystitis, one of the most common infections in man.The clinical studies were approved by the Human Ethics Committee at Lund University (approval numbers LU106-02, LU236-99 and Clinical Trial Registration RTP-A2003, International Committee of Medical Journal Editors, www.clinicaltrials.gov).
View details for DOI 10.1371/journal.ppat.1005848
View details for Web of Science ID 000387666900006
View details for PubMedID 27732661
View details for PubMedCentralID PMC5061333
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IRF7 inhibition prevents destructive innate immunity-A target for nonantibiotic therapy of bacterial infections
SCIENCE TRANSLATIONAL MEDICINE
2016; 8 (336): 336ra59
Abstract
Boosting innate immunity represents an important therapeutic alternative to antibiotics. However, the molecular selectivity of this approach is a major concern because innate immune responses often cause collateral tissue damage. We identify the transcription factor interferon regulatory factor 7 (IRF-7), a heterodimer partner of IRF-3, as a target for non-antibiotics-based therapy of bacterial infections. We found that the efficient and self-limiting innate immune response to bacterial infection relies on a tight balance between IRF-3 and IRF-7. Deletion of Irf3 resulted in overexpression of Irf7 and led to an IRF-7-driven hyperinflammatory phenotype, which was entirely prevented if Irf7 was deleted. We then identified a network of strongly up-regulated, IRF-7-dependent genes in Irf3(-/-) mice with kidney pathology, which was absent in Irf7(-/-) mice. IRF-3 and IRF-7 from infected kidney cell nuclear extracts were shown to bind OAS1, CCL5, and IFNB1 promoter oligonucleotides. These data are consistent in children with low IRF7 expression in the blood: attenuating IRF7 promoter polymorphisms (rs3758650-T and rs10902179-G) negatively associated with recurrent pyelonephritis. Finally, we identified IRF-7 as a target for immunomodulatory therapy. Administering liposomal Irf7 siRNA to Irf3(-/-) mice suppressed mucosal IRF-7 expression, and the mice were protected against infection and renal tissue damage. These findings offer a response to the classical but unresolved question of "good versus bad inflammation" and identify IRF7 as a therapeutic target for protection against bacterial infection.
View details for DOI 10.1126/scitranslmed.aaf1156
View details for Web of Science ID 000374833500004
View details for PubMedID 27122612
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Cytoprotective Effect of Lactobacillus crispatus CTV-05 against Uropathogenic E. coli
PATHOGENS
2016; 5 (1)
View details for DOI 10.3390/pathogens5010027
View details for Web of Science ID 000373680700018