Molecular determinants of disease severity in urinary tract infection

DEFA1A3 DNA gene-dosage regulates the kidney innate immune response during upper urinary tract infection

Antimicrobial peptides (AMPs) are host defense effectors with potent neutralizing and immunomodulatory functions against invasive pathogens. The AMPs α-Defensin 1-3/DEFA1A3 participate in innate immune responses and influence patient outcomes in various diseases. DNA copy-number variations in DEFA1A3 have been associated with severity and outcomes in infectious diseases including urinary tract infections (UTIs). Specifically, children with lower DNA copy numbers were more susceptible to UTIs. The mechanism of action by which α-Defensin 1-3/DEFA1A3 copy-number variations lead to UTI susceptibility remains to be explored. In this study, we use a previously characterized transgenic knock-in of the human DEFA1A3 gene mouse to dissect α-Defensin 1-3 gene dose-dependent antimicrobial and immunomodulatory roles during uropathogenic Escherichia coli (UPEC) UTI. We elucidate the relationship between kidney neutrophil- and collecting duct intercalated cell-derived α-Defensin 1-3/DEFA1A3 expression and UTI. We further describe cooperative effects between α-Defensin 1-3 and other AMPs that potentiate the neutralizing activity against UPEC. Cumulatively, we demonstrate that DEFA1A3 directly protects against UPEC meanwhile impacting pro-inflammatory innate immune responses in a gene dosage-dependent manner.

Similar immune responses to alpha1-oleate and Bacillus Calmette-Guérin treatment in patients with bladder cancer

BACKGROUND

The molecular content of urine is defined by filtration in the kidneys and by local release from tissues lining the urinary tract. Pathological processes and different therapies change the molecular composition of urine and a variety of markers have been analyzed in patients with bladder cancer. The response to BCG immunotherapy and chemotherapy has been extensively studied and elevated urine concentrations of IL-1RA, IFN-α, IFN-γ TNF-α, and IL-17 have been associated with improved outcome.

METHODS

In this study, the host response to intravesical alpha 1-oleate treatment was characterized in patients with non-muscle invasive bladder cancer by proteomic and transcriptomic analysis.

RESULTS

Proteomic profiling detected a significant increase in multiple cytokines in the treatment group compared to placebo. The innate immune response was strongly activated, including IL-1RA and pro-inflammatory cytokines in the IL-1 family (IL-1α, IL-1β, IL-33), chemokines (MIP-1α, IL-8), and interferons (IFN-α2, IFN-γ). Adaptive immune mediators included IL-12, Granzyme B, CD40, PD-L1, and IL-17D, suggesting broad effects of alpha 1-oleate treatment on the tumor tissues.

CONCLUSIONS

The cytokine response profile in alpha 1-oleate treated patients was similar to that reported in BCG treated patients, suggesting a significant overlap. A reduction in protein levels at the end of treatment coincided with inhibition of cancer-related gene expression in tissue biopsies, consistent with a positive treatment effect. Thus, in addition to killing tumor cells and inducing cell detachment, alpha 1-oleate is shown to activate a broad immune response with a protective potential.

MANNosylation of Mesoporous Silica Nanoparticles Modifies TLR4 Localization and NF-κB Translocation in T24 Bladder Cancer Cells

D-mannose is widely used as non-antibiotic treatment for bacterial urinary tract infections. This application is based on a well-studied mechanism of binding to the type 1 bacterial pili and, therefore, blocking bacteria adhesion to the uroepithelial cells. To implement D-mannose into carrier systems, the mechanism of action of the sugar in the bladder environment is also relevant and requires investigation. Herein, two different MANNosylation strategies using mesoporous silica nanoparticles (MSNs) are described. The impact of different chemical linkers on bacterial adhesion and bladder cell response is studied via confocal microscopy imaging of the MSN interactions with the respective organisms. Cytotoxicity is assessed and the expression of Toll-like receptor 4 (TLR4) and caveolin-1 (CAV-1), in the presence or absence of simulated infection with bacterial lipopolysaccharide (LPS), is evaluated using the human urinary bladder cancer cell line T24. Further, localisation of the transcription factor NF-κB due to the MANNosylated materials is examined over time. The results show that MANNosylation modifies bacterial adhesion to the nanomaterials and significantly affects TLR4, caveolin-1, and NF-κB in bladder cells. These elements are essential components of the inflammatory cascade/pathogens response during urinary tract infections. These findings demonstrate that MANNosylation is a versatile tool to design hybrid nanocarriers for targeted biomedical applications.

Machine Learning-Assistant Colorimetric Sensor Arrays for Intelligent and Rapid Diagnosis of Urinary Tract Infection

Urinary tract infections (UTIs), which can lead to pyelonephritis, urosepsis, and even death, are among the most prevalent infectious diseases worldwide, with a notable increase in treatment costs due to the emergence of drug-resistant pathogens. Current diagnostic strategies for UTIs, such as urine culture and flow cytometry, require time-consuming protocols and expensive equipment. We present here a machine learning-assisted colorimetric sensor array based on recognition of ligand-functionalized Fe single-atom nanozymes (SANs) for the identification of microorganisms at the order, genus, and species levels. Colorimetric sensor arrays are built from the SAN Fe1-NC functionalized with four types of recognition ligands, generating unique microbial identification fingerprints. By integrating the colorimetric sensor arrays with a trained computational classification model, the platform can identify more than 10 microorganisms in UTI urine samples within 1 h. Diagnostic accuracy of up to 97% was achieved in 60 UTI clinical samples, holding great potential for translation into clinical practice applications.

Photochemical inactivation as an alternative method to produce a whole-cell vaccine for uropathogenic Escherichia coli (UPEC)

Uropathogenic Escherichia coli (UPEC) is the primary causative agent of lower urinary tract infection (UTI). UTI presents a serious health risk and has considerable secondary implications including economic burden, recurring episodes, and overuse of antibiotics. A safe and effective vaccine would address this widespread health problem and emerging antibiotic resistance. Killed, whole-cell vaccines have shown limited efficacy to prevent recurrent UTI in human trials. We explored photochemical inactivation with psoralen drugs and UVA light (PUVA), which crosslinks nucleic acid, as an alternative to protein-damaging methods of inactivation to improve whole-cell UTI vaccines. Exposure of UPEC to the psoralen drug AMT and UVA light resulted in a killed but metabolically active (KBMA) state, as reported previously for other PUVA-inactivated bacteria. The immunogenicity of PUVA-UPEC as compared to formalin-inactivated UPEC was compared in mice. Both generated high UPEC-specific serum IgG titers after intramuscular delivery. However, using functional adherence as a measure of surface protein integrity, we found differences in the properties of PUVA- and formalin-inactivated UPEC. Adhesion mediated by Type-1 and P-fimbriae was severely compromised by formalin but was unaffected by PUVA, indicating that PUVA preserved the functional conformation of fimbrial proteins, which are targets of protective immune responses. In vitro assays indicated that although they retained metabolic activity, PUVA-UPEC lost virulence properties that could negatively impact vaccine safety. Our results imply the potential for PUVA to improve killed, whole-cell UTI vaccines by generating bacteria that more closely resemble their live, infectious counterparts relative to vaccines generated with protein-damaging methods.

IMPORTANCE

Lower urinary tract infection (UTI), caused primarily by uropathogenic Escherichia coli, represents a significant health burden, accounting for 7 million primary care and 1 million emergency room visits annually in the United States. Women and the elderly are especially susceptible and recurrent infection (rUTI) is common in those populations. Lower UTI can lead to life-threatening systemic infection. UTI burden is manifested by healthcare dollars spent (1.5 billion annually), quality of life impact, and resistant strains emerging from antibiotic overuse. A safe and effective vaccine to prevent rUTI would address a substantial healthcare issue. Vaccines comprised of inactivated uropathogenic bacteria have yielded encouraging results in clinical trials but improvements that enhance vaccine performance are needed. To that end, we focused on inactivation methodology and provided data to support photochemical inactivation, which targets nucleic acid, as a promising alternative to conventional protein-damaging inactivation methods to improve whole-cell UTI vaccines.

Collectin 11 has a pivotal role in host defense against kidney and bladder infection in mice

The urinary tract is constantly exposed to microorganisms. Host defense mechanisms in protection from microbial colonization and development of urinary tract infections require better understanding to control kidney infection. Here we report that the lectin collectin 11 (CL-11), particularly kidney produced, has a pivotal role in host defense against uropathogen infection. CL-11 was found in mouse urine under normal and pathological conditions. Mice with global gene ablation of Colec11 had increased susceptibility to and severity of kidney and to an extent, bladder infection. Mice with kidney-specific Colec11 ablation exhibited a similar disease phenotype to that observed in global Colec11 deficient mice, indicating the importance of kidney produced CL-11 for protection against kidney and bladder infection. Conversely, intravesical or systemic administration of recombinant CL-11 reduced susceptibility to and severity of kidney and bladder infection. Mechanism analysis revealed that CL-11 can mediate several key innate defense mechanisms (agglutination, anti- adhesion, opsonophagocytosis), and limit local inflammatory responses to pathogens. Furthermore, CL-11-mediated innate defense mechanisms can act on clinically relevant microorganisms including multiple antibiotic resistant strains. CL-11 was detectable in eight of 24 urine samples from patients with urinary tract infections but not detectable in urine samples from ten healthy individuals. Thus, our findings demonstrate that CL-11 is a key factor of host defense mechanisms in kidney and bladder infection with therapeutic potential for human application.

Correlation between antimicrobial resistance, biofilm formation, and virulence determinants in uropathogenic Escherichia coli from Egyptian hospital

BACKGROUND

Uropathogenic Escherichia coli (UPEC) is the main etiological agent behind community-acquired and hospital-acquired urinary tract infections (UTIs), which are among the most prevalent human infections. The management of UPEC infections is becoming increasingly difficult owing to multi-drug resistance, biofilm formation, and the possession of an extensive virulence arsenal. This study aims to characterize UPEC isolates in Tanta, Egypt, with regard to their antimicrobial resistance, phylogenetic profile, biofilm formation, and virulence, as well as the potential associations among these factors.

METHODS

One hundred UPEC isolates were obtained from UTI patients in Tanta, Egypt. Antimicrobial susceptibility was assessed using the Kirby-Bauer method. Extended-spectrum β-lactamases (ESBLs) production was screened using the double disk synergy test and confirmed with PCR. Biofilm formation was evaluated using the microtiter-plate assay and microscopy-based techniques. The phylogenetic groups of the isolates were determined. The hemolytic activity, motility, siderophore production, and serum resistance of the isolates were also evaluated. The clonal relatedness of the isolates was assessed using ERIC-PCR.

RESULTS

Isolates displayed elevated resistance to cephalosporins (90-43%), sulfamethoxazole-trimethoprim (63%), and ciprofloxacin (53%). Ninety percent of the isolates were multidrug-resistant (MDR)/ extensively drug-resistant (XDR) and 67% produced ESBLs. Notably, there was an inverse correlation between biofilm formation and antimicrobial resistance, and 31%, 29%, 32%, and 8% of the isolates were strong, moderate, weak, and non-biofilm producers, respectively. Beta-hemolysis, motility, siderophore production, and serum resistance were detected in 64%, 84%, 65%, and 11% of the isolates, respectively. Siderophore production was correlated to resistance to multiple antibiotics, while hemolysis was more prevalent in susceptible isolates and associated with stronger biofilms. Phylogroups B2 and D predominated, with lower resistance and stronger biofilms in group B2. ERIC-PCR revealed considerable diversity among the isolates.

CONCLUSION

This research highlights the dissemination of resistance in UPEC in Tanta, Egypt. The evident correlation between biofilm and resistance suggests a resistance cost on bacterial cells; and that isolates with lower resistance may rely on biofilms to enhance their survival. This emphasizes the importance of considering biofilm formation ability during the treatment of UPEC infections to avoid therapeutic failure and/or infection recurrence.

Fabrication of levofloxacin-loaded porcine acellular dermal matrix hydrogel and functional assessment in urinary tract infection

Bacterial cystitis, a commonly occurring urinary tract infection (UTI), is renowned for its extensive prevalence and tendency to recur. Despite the extensive utilization of levofloxacin as a conventional therapeutic approach for bacterial cystitis, its effectiveness is impeded by adverse toxic effects, drug resistance concerns, and its influence on the gut microbiota. This study introduces Lev@PADM, a hydrogel with antibacterial properties that demonstrates efficacy in the treatment of bacterial cystitis. Lev@PADM is produced by combining levofloxacin with decellularized porcine acellular dermal matrix hydrogel and exhibits remarkable biocompatibility. Lev@PADM demonstrates excellent stability as a hydrogel at body temperature, enabling direct administration to the site of infection through intravesical injection. This localized delivery route circumvents the systemic circulation of levofloxacin, resulting in a swift and substantial elevation of the antimicrobial agent's concentration specifically at the site of infection. The in vivo experimental findings provide evidence that Lev@PADM effectively prolongs the duration of levofloxacin's action, impedes the retention and invasion of E.coli in the urinary tract, diminishes the infiltration of innate immune cells into infected tissues, and simultaneously preserves the composition of the intestinal microbiota. These results indicate that, in comparison to the exclusive administration of levofloxacin, Lev@PADM offers notable benefits in terms of preserving the integrity of the bladder epithelial barrier and suppressing the recurrence of urinary tract infections.

Exosomes derived from bladder epithelial cells infected with uropathogenic Escherichia coli increase the severity of urinary tract infections (UTIs) by impairing macrophage function

Uropathogenic Escherichia coli (UPEC) is the primary causative agent of urinary tract infections (UTIs) in humans. Moreover, as one of the most common bacterial pathogens, UPEC imposes a substantial burden on healthcare systems worldwide. Epithelial cells and macrophages are two major components of the innate immune system, which play critical roles in defending the bladder against UPEC invasion. Yet, the routes of communication between these cells during UTI pathogenesis are still not fully understood. In the present study, we investigated the role of membrane-bound nanovesicles (exosomes) in the communication between bladder epithelial cells and macrophages during UPEC infection, using an array of techniques such as flow cytometry, miRNA profiling, RNA sequencing, and western blotting. Moreover, our in vitro findings were validated in a mouse model of UPEC-induced cystitis. We found that UPEC infection induced the bladder epithelial MB49 cell line to secrete large numbers of exosomes (MB49-U-Exo), which were efficiently absorbed by macrophages both in vivo and in vitro. Assimilation of MB49-U-Exo induced macrophages to produce proinflammatory cytokines, including tumor necrosis factor (TNF)α. Exposure of macrophages to MB49-U-Exo reduced their phagocytic activity (by downregulating the expression of phagocytosis-related genes) and increased their rate of apoptosis. Mechanistically, we showed that MB49-U-Exo were enriched in miR-18a-5p, which induced TNFα expression in macrophages by targeting PTEN and activating the MAPK/JNK signaling pathway. Moreover, administration of the exosome secretion inhibitor GW4869 or a TNFα-neutralizing antibody alleviated UPEC-mediated tissue damage in mice with UPEC-induced cystitis by reducing the bacterial burden of the bladder and dampening the associated inflammatory response. Collectively, these findings suggest that MB49-U-Exo regulate macrophage function in a way that exacerbates UPEC-mediated tissue impairment. Thus, targeting exosomal -release or TNFα signaling during UPEC infection may represent promising non-antibiotic strategies for treating UTIs.

Therapeutic Effects of IL-1RA against Acute Bacterial Infections, including Antibiotic-Resistant Strains

Innate immunity is essential for the anti-microbial defense, but excessive immune activation may cause severe disease. In this study, immunotherapy was shown to prevent excessive innate immune activation and restore the anti-bacterial defense. E. coli-infected Asc-/- mice develop severe acute cystitis, defined by IL-1 hyper-activation, high bacterial counts, and extensive tissue pathology. Here, the interleukin-1 receptor antagonist (IL-1RA), which inhibits IL-1 hyper-activation in acute cystitis, was identified as a more potent inhibitor of inflammation and NK1R- and substance P-dependent pain than cefotaxime. Furthermore, IL-1RA treatment inhibited the excessive innate immune activation in the kidneys of infected Irf3-/- mice and restored tissue integrity. Unexpectedly, IL-1RA also accelerated bacterial clearance from infected bladders and kidneys, including antibiotic-resistant E. coli, where cefotaxime treatment was inefficient. The results suggest that by targeting the IL-1 response, control of the innate immune response to infection may be regained, with highly favorable treatment outcomes, including infections caused by antibiotic-resistant strains.

A human urothelial microtissue model reveals shared colonization and survival strategies between uropathogens and commensals

Urinary tract infection is among the most common infections worldwide, typically studied in animals and cell lines with limited uropathogenic strains. Here, we assessed diverse bacterial species in a human urothelial microtissue model exhibiting full stratification, differentiation, innate epithelial responses, and urine tolerance. Several uropathogens invaded intracellularly, but also commensal Escherichia coli, suggesting that invasion is a shared survival strategy, not solely a virulence hallmark. The E. coli adhesin FimH was required for intracellular bacterial community formation, but not for invasion. Other shared lifestyles included filamentation (Gram-negatives), chaining (Gram-positives), and hijacking of exfoliating cells, while biofilm-like aggregates were formed mainly with Pseudomonas and Proteus. Urothelial cells expelled invasive bacteria in Rab-/LC3-decorated structures, while highly cytotoxic/invasive uropathogens, but not commensals, disrupted host barrier function and strongly induced exfoliation and cytokine production. Overall, this work highlights diverse species-/strain-specific infection strategies and corresponding host responses in a human urothelial microenvironment, providing insights at the microtissue, cell, and molecular level.

MicroRNA-146b protects kidney injury during urinary tract infections by modulating macrophage polarization

Urinary tract infections (UTIs) caused by uropathogenic Escherichia coli (UPEC) can lead to severe kidney injury. However, the molecular mechanisms underlying the pathological process of kidney injury are still incompletely understood. In the present study, we demonstrate that microRNA-146b (miR-146b) deficiency aggravates kidney injury during UTIs caused by UPEC. In a mouse kidney infection model utilizing urosepsis isolate CFT073, we found that miR-146b expression significantly increased in the early stages of UPEC infection. Also, miR-146b-deficient mice displayed exacerbated inflammation in the kidney injury with severe M1 macrophage infiltration. Additionally, the results showed that miR-146b targeted interferon regulatory factor 5-regulated M1 macrophage polarization during UTIs. The results suggested that miR-146b contributed significantly to the control of kidney damage during UTIs, highlighting that miR-146b might be used as a novel therapeutic target for treating kidney injury during UTIs. IMPORTANCE Kidney injury during acute urinary tract infections (UTIs) caused by uropathogenic Escherichia coli (UPEC) is an important public health problem. However, how kidney injury develops during UPEC infection is still unclear. Although antibiotic therapy is currently an effective treatment for UTI, it cannot avoid kidney injury. MicroRNAs have gained extensive attention as essential molecules capable of regulating the autoimmune response. Among these, microRNA-146b (miR-146b) is involved in regulating inflammatory responses. In the present study, we demonstrated that miR-146b played an essential role in the development of kidney injury during UTIs caused by UPEC. The results showed that miR-146b may suppress M1 macrophage polarization and alleviate acute kidney injury. Furthermore, the miR-146b activator, agomir, in order to upregulate miR-146b, was effective in treating kidney damage by inhibiting the activation of M1 macrophages. In conclusion, our findings elucidated the mechanisms by which miR-146b alleviated kidney injury induced by UTIs, shed new light on the relationship between microRNA and bacterial infection, and provided a novel therapeutic target for treating this common bacterial infection.

The Impact of Infections on the Progression of Chronic Kidney Disease

Background and Objective: Infectious diseases continue to be a global burden and their impact is even worse if the patients already have other comorbidities. Because chronic kidney disease is very frequent, affecting 10% of the population, our study aims to explore the impact that infectious events have on its progression. Material and Methods: This is a retrospective, observational study based on a cohort of 238 dialyzed patients from the Nephrology Clinic of "Dr. Carol Davila" Clinical Hospital of Nephrology, Bucharest, who were followed from their first visit for five years, between 1 January 2007 and 1 January 2022. For each of them, the presence of an infectious event and the moment of the initiation of dialysis were recorded. Results: Statistical analysis showed that the patients who had at least one infectious episode were older (p = 0.004), their hemoglobin and lymphocytes were significantly lower (p = 0.03 and p = 0.02, respectively) and the time until the initiation of dialysis was lower (p = 0.007). Also, the preservation of kidney function was influenced by the number and the severity of infectious episodes. In the univariate Cox model, the following variables were associated with increased risk of dialysis: advanced age (p: 0.009; HR: 1.021; CI: 1.005 to 1.036), low hemoglobin (p: 0.001; HR: 0.861; CI: 0.786 to 0.943), previous diagnosis of chronic obstructive pulmonary disease (p: 0.002; HR: 2.467; CI: 1.376 to 4.424), presence of hematuria (p: 0.03; HR: 1.604; CI: 1.047 to 2.457) and increased values of proteinuria (p: 0.01; HR: 1.122; CI: 1.028 to 1.224) and of serum creatinine measured both at the time of the first visit and at the time of each infectious event (p: <0.001; HR: 1.262; CI: 1.141 to 1.396). Also, the presence of an infectious episode was associated with a 1.7-fold increase in the risk of dialysis initiation. The independent predictors of survival identified by the multivariate Cox model were age (p: 0.004; HR: 1.034; CI: 1.010-1.058), serum creatinine (p: <0.001; HR: 1.421; CI: 1.203 to 1.658) and proteinuria (p: <0.001; HR: 1.241; CI: 1.126 to 1.369) at the time of enrollment, but also the presence of an infectious episode during the patient's evolution (p: 0.04; HR: 1.705; CI: 1.013 to 2.868). Conclusions: In the evolution of patients with chronic kidney disease, an active search for individual factors favoring the occurrence of infectious episodes should be taken into consideration to prevent a faster progression toward end-stage kidney disease.

Uropathogen and host responses in pyelonephritis

Urinary tract infections (UTIs) are among the most common bacterial infections seen in clinical practice. The ascent of UTI-causing pathogens to the kidneys results in pyelonephritis, which can trigger kidney injury, scarring and ultimately impair kidney function. Despite sizable efforts to understand how infections develop or are cleared in the bladder, our appreciation of the mechanisms by which infections develop, progress or are eradicated in the kidney is limited. The identification of virulence factors that are produced by uropathogenic Escherichia coli to promote pyelonephritis have begun to fill this knowledge gap, as have insights into the mechanisms by which kidney tubular epithelial cells oppose uropathogenic E. coli infection to prevent or eradicate UTIs. Emerging data also illustrate how specific cellular immune responses eradicate infection whereas other immune cell populations promote kidney injury. Insights into the mechanisms by which uropathogenic E. coli circumvent host immune defences or antibiotic therapy to cause pyelonephritis is paramount to the development of new prevention and treatment strategies to mitigate pyelonephritis and its associated complications.

The Role of Mobile Genetic Elements in Virulence Factor Carriage from Symptomatic and Asymptomatic Cases of Escherichia coli Bacteriuria

Uropathogenic Escherichia coli (UPEC) is extremely diverse genotypically and phenotypically. Individual strains can variably carry diverse virulence factors, making it challenging to define a molecular signature for this pathotype. For many bacterial pathogens, mobile genetic elements (MGEs) constitute a major mechanism of virulence factor acquisition. For urinary E. coli, the total distribution of MGEs and their role in the acquisition of virulence factors is not well defined, including in the context of symptomatic infection versus asymptomatic bacteriuria (ASB). In this work, we characterized 151 isolates of E. coli, derived from patients with either urinary tract infection (UTI) or ASB. For both sets of E. coli, we catalogued the presence of plasmids, prophage, and transposons. We analyzed MGE sequences for the presence of virulence factors and antimicrobial resistance genes. These MGEs were associated with only ~4% of total virulence associated genes, while plasmids contributed to ~15% of antimicrobial resistance genes under consideration. Our analyses suggests that, across strains of E. coli, MGEs are not a prominent driver of urinary tract pathogenesis and symptomatic infection. IMPORTANCE Escherichia coli is the most common etiological agent of urinary tract infections (UTIs), with UTI-associated strains designated "uropathogenic" E. coli or UPEC. Across urinary strains of E. coli, the global landscape of MGEs and its relationship to virulence factor carriage and clinical symptomatology require greater clarity. Here, we demonstrate that many of the putative virulence factors of UPEC are not associated with acquisition due to MGEs. The current work enhances our understanding of the strain-to-strain variability and pathogenic potential of urine-associated E. coli and points toward more subtle genomic differences distinguishing ASB from UTI isolates.

Kidney medullary sodium chloride concentrations induce neutrophil and monocyte extracellular DNA traps that defend against pyelonephritis in vivo

Urinary tract infections are common. Here, we delineate a role of extracellular DNA trap (ET) formation in kidney antibacterial defense and determine mechanisms of their formation in the hyperosmotic environment of the kidney medulla. ET of granulocytic and monocytic origin were present in the kidneys of patients with pyelonephritis along with systemically elevated citrullinated histone levels. Inhibition of the transcription coregulatory, peptidylarginine deaminase 4 (PAD4), required for ET formation, prevented kidney ET formation and promoted pyelonephritis in mice. ETs predominantly accumulated in the kidney medulla. The role of medullary sodium chloride and urea concentrations in ET formation was then investigated. Medullary-range sodium chloride, but not urea, dose-, time- and PAD4-dependently induced ET formation even in the absence of other stimuli. Moderately elevated sodium chloride promoted myeloid cell apoptosis. Sodium gluconate also promoted cell death, proposing a role for sodium ions in this process. Sodium chloride induced myeloid cell calcium influx. Calcium ion-free media or -chelation reduced sodium chloride-induced apoptosis and ET formation while bacterial lipopolysaccharide amplified it. Autologous serum improved bacterial killing in the presence of sodium chloride-induced ET. Depletion of the kidney sodium chloride gradient by loop diuretic therapy diminished kidney medullary ET formation and increased pyelonephritis severity. Thus, our data demonstrate that ETs may protect the kidney against ascending uropathogenic E. coli and delineate kidney medullary range sodium chloride concentrations as novel inducers of programmed myeloid cell death.

Chronic Kidney Disease, Urinary Tract Infections and Antibiotic Nephrotoxicity: Are There Any Relationships?

Chronic kidney disease (CKD) has been a constant burden worldwide, with a prevalence of more than 10% of the population and with mortality reaching 1.2 million deaths and 35.8 million disability-adjusted life years (DALYs) in 2017, as it is claimed by the Global Burden of Diseases. Moreover, an increase in its prevalence is expected in the next years due to a rise in the number of people suffering from obesity, diabetes mellitus and hypertension. On the other hand, with cardiovascular morbidity and mortality showing a downward trend, maybe it is time to focus on CKD, to minimize the preventable risk factors involved in its progression toward end-stage kidney disease (ESKD) and to offer a better quality of life. Another major health burden is represented by infectious diseases, particularly urinary tract infections (UTIs), as it is considered that approximately 40-50% of women and 5% of men will have at least one episode during their lifetime. Additionally, CKD consists of a constellation of immunological and metabolical disturbances that lead to a greater risk of UTIs: increased apoptosis of lymphocytes, elevated levels of tumor necrosis factor α and interleukin 6, which lower the function of neutrophils and increased levels of uremic toxins like p-cresyl sulfate and indoxyl sulfate, which alter the adherence and migration of leukocytes to the sites of injury. Moreover, UTIs can lead to a more rapid decline of kidney function, especially in stages G3-G5 of CKD, with all the complications involved. Last, but not least, antibiotherapy is often complicated in this category of patients, as antibiotics can also negatively affect the kidneys. This review will try to focus on the particularities of the urinary microbiome, asymptomatic bacteriuria and UTIs and the subtle balance between the risks of them and the risks of antibiotherapy in the evolution of CKD.

The role of pathogens in diabetes pathogenesis and the potential of immunoproteomics as a diagnostic and prognostic tool

Diabetes mellitus (DM) is a group of metabolic diseases marked by hyperglycemia, which increases the risk of systemic infections. DM patients are at greater risk of hospitalization and mortality from bacterial, viral, and fungal infections. Poor glycemic control can result in skin, blood, bone, urinary, gastrointestinal, and respiratory tract infections and recurrent infections. Therefore, the evidence that infections play a critical role in DM progression and the hazard ratio for a person with DM dying from any infection is higher. Early diagnosis and better glycemic control can help prevent infections and improve treatment outcomes. Perhaps, half (49.7%) of the people living with DM are undiagnosed, resulting in a higher frequency of infections induced by the hyperglycemic milieu that favors immune dysfunction. Novel diagnostic and therapeutic markers for glycemic control and infection prevention are desirable. High-throughput blood-based immunoassays that screen infections and hyperglycemia are required to guide timely interventions and efficiently monitor treatment responses. The present review aims to collect information on the most common infections associated with DM, their origin, pathogenesis, and the potential of immunoproteomics assays in the early diagnosis of the infections. While infections are common in DM, their role in glycemic control and disease pathogenesis is poorly described. Nevertheless, more research is required to identify novel diagnostic and prognostic markers to understand DM pathogenesis and management of infections. Precise monitoring of diabetic infections by immunoproteomics may provide novel insights into disease pathogenesis and healthy prognosis.

TcpC Inhibits M1 but Promotes M2 Macrophage Polarization via Regulation of the MAPK/NF-κB and Akt/STAT6 Pathways in Urinary Tract Infection

Abstract

TcpC is a multifunctional virulence factor of Uropathogenic Escherichia coli (UPEC). Macrophages can differentiate into two different subsets M1 and M2 that play distinct roles in anti-infection immunity. Here, we investigate the influence of TcpC on M1/M2 polarization and the potential mechanisms. Our data showed that M1 markers CD86 and iNOS were significantly inhibited, while the M2 markers CD163, CD206 and Arg-1 were enhanced in macrophages in kidneys from the TcpC-secreting wild-type CFT073 (CFT073^wt)-infected pyelonephritis mouse model, compared with those in macrophages in kidneys from TcpC knockout CFT073 mutant (CFT073^Δtcpc)-infected mice. CFT073^wt or recombinant TcpC (rTcpC) treatment inhibits LPS + IFN-γ-induced CD80, CD86, TNF-α and iNOS expression, but promotes IL-4-induced CD163, CD206, Arg-1 and IL-10 expression in both human and mouse macrophage cell lines THP-1 and J774A.1. Moreover, rTcpC significantly attenuated LPS + IFN-γ-induced phosphorylation of p38, ERK, p50 and p65 but enhanced IL-4-induced phosphorylation of Akt and STAT6. These data suggest that TcpC inhibits M1 but promotes M2 macrophage polarization by down-regulation of p38, ERK/NF-κB and up-regulation of the Akt/STAT6 signaling pathway, respectively. Our findings not only illuminate the regulatory effects of TcpC on macrophage M1/M2 polarization and its related signaling pathways, but also provide a novel mechanism underlying TcpC-mediated immune evasion of macrophage-mediated innate immunity.

Simple Summary

We investigate the influence of TcpC, a multifunctional virulence factor of Uropathogenic Escherichia coli (UPEC), on M1/M2 macrophage polarization and the potential mechanisms. TcpC-secreting wild-type CFT073 (CFT073^wt) or recombinant TcpC (rTcpC) treatment inhibits LPS + IFN-γ-induced CD80, CD86, TNF-α and iNOS expression, but promotes IL-4-induced CD163, CD206, Arg-1 and IL-10 expression in CFT073^wt-infected pyelonephritis model mouse and both human and mouse macrophage cell lines THP-1 and J774A.1, respectively. Moreover, rTcpC significantly attenuated LPS + IFN-γ-induced phosphorylation of p38, ERK, p50 and p65 but en-hanced IL-4-induced phosphorylation of Akt and STAT6. These data suggest that TcpC inhibits M1 but promotes M2 macrophage polarization by down-regulation of p38, ERK/NF-κB and up-regulation of the Akt/STAT6 signaling pathway, respectively. Our findings not only illuminate the regulatory effects of TcpC on macrophage M1/M2 polarization and its related signaling pathways, but also provide a novel mechanism underlying TcpC-mediated immune evasion of macrophage-mediated innate immunity.

Phylogenetic groups, serogroups and virulence factors of uropathogenic Escherichia coli isolated from patients with urinary tract infection in Baghdad, Iraq

Background and Objectives

Uropathogenic Escherichia coli (UPEC) is divided into different phylogenetic groups that differ in their antibiotic resistance patterns, serogroups and pathogenicity. This study aimed to investigate the prevalence of phylogenetic groups of UPEC isolates and their relationship with serogroups and virulence factors in patients with UTIs.

Materials and Methods

Of the 412 urine samples tested a total of 150 UPEC were isolated and confirmed with PCR using 16S rRNA gene. Antibiotic resistance of the isolates was tested using disk diffusion method and the isolates were divided into phylogenetic groups by the quadruplex PCR method. The prevalence of serogroups and virulence genes were investigated using multiplex PCR.

Results

87 (58%) of the isolates belonged to phylogroup B2. Virulence genes fimH (95.3%), aer (49.3%) and serogroups O8 (22.3%), O25 (21.5%) showed the highest prevalence. The lowest drug resistance was observed against imipenem (4.6%) and meropenem (3.3%). The prevalence of multidrug-resistant and extended-spectrum beta-lactamases isolates were 60% and 61.3%, respectively. We also found a significant relationship between phylogenetic groups, serogroups and virulence factors among our isolates.

Conclusion

The high abundance of phylogenetic group B2, serogroups O8 and O25, and virulence genes fimH and aer indicate their importance in the pathogenesis of UPEC in this country.

Interactions of Bacterial Toxin CNF1 and Host JAK1/2 Driven by Liquid-Liquid Phase Separation Enhance Macrophage Polarization

Urinary tract infections (UTIs) are a global public health concern, which is mainly caused by uropathogenic Escherichia coli (UPEC). Cytotoxic necrotizing factor 1 (CNF1) is a key UPEC toxin and regulates multiple host cellular processes through activating the Rho GTPases; however, the effect of CNF1 on macrophage polarization remains unknown. Here, we found that CNF1 promoted M1 macrophage polarization through regulating NF-κB and JAK-STAT1 signaling pathways in kidney at an early stage of acute UTIs. Notably, we identified CNF1 could directly interact with JAK1/2 through its domain without Rho GTPases activation, which induced JAK1/2 phosphorylation, subsequent STAT1 activation and M1 polarization. Moreover, CNF1 exhibited liquid-liquid phase separation (LLPS) to induce a CNF1-JAK1/2 complex, promoting macrophage reprogramming. These findings highlight the LLPS-dependent and Rho GTPase-independent effect of CNF1 as an adaptor on interfering with host cell signals.

Immunomodulation therapy offers new molecular strategies to treat UTI

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.

Hyperactivation of innate immunity is a disease determinant in urinary tract infections (UTIs). Modulation of innate immunity has promise as a therapy for UTIs. In this Review, the authors discuss potential mechanisms and immunomodulatory therapeutic strategies in UTIs.

Excessive innate immune responses to infection cause symptoms and pathology in acute pyelonephritis and acute cystitis.

Innate immunomodulation therapy is, therefore, a realistic option for treating these conditions.

Targeting excessive innate immune responses at the level of transcription has been successful in animal models.

Innate immunomodulation therapy reduces excessive inflammation and tissue pathology and accelerates bacterial clearance from infected kidneys and bladders in mice.

Innate immunomodulation therapy also accelerates the clearance of antibiotic-resistant bacterial strains.

The C5a/C5aR1 Axis Contributes to the Pathogenesis of Acute Cystitis Through Enhancement of Adhesion and Colonization of Uropathogenic E. coli

Our previous work using a murine model of pyelonephritis demonstrated that the C5a/C5aR1 axis plays a pathogenic role in acute kidney infection. In this study, we report that the C5a/C5aR1 axis also plays a pathogenic role in acute bladder infection. C5aR1-deficient mice had reduced bladder bacterial load and attenuated bladder tissue injury, which is associated with reduced expression of terminal α-mannosyl residues (Man) (a potential ligand for type 1 fimbriae of E. coli) at the luminal surface of the bladder epithelium and reduced early bacterial colonization of the bladder. In vitro, C5a stimulation enhanced mannose expression in and facilitated bacterial adhesion/colonization to human bladder epithelial cells. C5a stimulation also upregulated the activation of ERK1/2 and NF-κB signaling and gene expression of proinflammatory cytokines (i.e., Il6, Il1b, Cxcl1, Ccl2) in the epithelial cells, which could drive pro-inflammatory responses leading to tissue injury. Administration of the C5aR1 antagonist effectively reduced bladder bacterial load and tissue injury. Thus, our findings demonstrate a previously unknown pathogenic role for the C5a/C5aR1 axis in bladder infection and suggest that the C5a/C5aR1 axis-mediated upregulation of Man expression, enhancement of bacterial adhesion/colonization, and excessive inflammatory responses contribute to acute bladder infection. These findings improve our understanding of the pathogenesis of bladder infection with therapeutic implications for UTI.