Involvement of NLRP3 and NLRC4 Inflammasome in Uropathogenic E. coli Mediated Urinary Tract Infections

Study on the therapeutic mechanism of HJ granules in a rat model of urinary tract infection caused by Escherichia coli

ETHNOPHARMACOLOGICAL RELEVANCE

Urinary tract infections (UTIs) are globally prevalent infectious diseases, predominantly caused by uropathogenic Escherichia coli (UPEC). The misuse of antibiotics has led to the emergence of several drug-resistant strains. Traditional Chinese Medicine (TCM) has its own advantages in the treatment of UTIs. HJ granules is a herbal formula used for the treatment of UTIs. However, its mechanism of action is not clear.

AIM OF THE STUDY

The aim of this study was to investigate the therapeutic efficacy and mechanism of action of HJ granules in a rat model of UTI caused by Escherichia coli (E coli) CFT073.

MATERIALS AND METHODS

SD rats were selected to establish a rat UTI model by injecting UPEC strain CFT073 into the bladder using the transurethral placement method. HJ granules were administered to rats after modelling and the efficacy of HJ granule was investigated by measuring urinary decanalogue, inflammatory factors in bladder tissue and pathological changes in the bladder after 3d of administration. Expression of sonic hedgehog (SHH), NOD-like receptor thermoprotein domain 3 (NLRP3), apoptosis-associated speck-like protein (ASC) and activation of cysteinyl aspartate specific proteinase-1 (caspase-1) were detected by western blotting and immunofluorescence staining in rat bladder tissue. NLRP3, ASC and caspase-1, a cysteine-containing aspartic protein, were expressed and activated.

RESULTS

The results showed that infection of rats with UPEC resulted in increased pH and erythrocytes in bladder irrigation fluid; increased expression of IL-1β, IL-6 and SHH and decreased expression of IL-10 in bladder tissue; and significant upregulation of the expression of both SHH and NLRP3 inflammasom and significant activation of NLRP3 inflammasom. HJ granules significantly increased the concentration of IL-10 in the bladder, inhibited the expression of SHH and NLRP3 inflammasom in bladder tissue, and suppressed the activation of NLRP3 inflammasom, thereby reducing inflammatory lesions in bladder tissue.

CONCLUSION

HJ granules may improve bladder injury and treat UTIs by inhibiting the expression and activation of NLRP3 inflammasom.

Antimicrobial lipids loaded on lectin display reduced MIC, curtail pathogenesis and protect zebrafish from reinfection by immunomodulation

Antibiotic resistance and re-emergence of highly resistant pathogens is a grave concern everywhere and this has consequences for all kinds of human activities. Herein, we showed that N-palmitoylethanolamine-derived cationic lipid (cN16E) had a lower minimum inhibitory concentration (MIC) against both Gram-positive and Gram-negative bacteria when it was loaded with Butea monosperma seed lectin (BMSL). The analysis using lectin-FITC conjugate labelling indicated that the improved antibacterial activity of BMSL conjugation was due to bacterial cell surface glycan recognition. Live and dead staining experiments revealed that the BMSL-cN16E conjugate (BcN16E) exerts antibacterial activity by damaging the bacterial membrane. BcN16E antimicrobial activity was demonstrated using an infected zebrafish animal model because humans have 70 % genetic similarity to zebrafish. BcN16E therapeutic potential was established successfully by rescuing fish infected with uropathogenic Escherichia coli (UPEC). Remarkably, the rescued infected fish treated with BcN16E prevented reinfection without further therapy, indicating BcN16E immunomodulatory potential. Thus, the study examined the expression of immune-related genes, including tnfα, ifnγ, il-1β, il-4, il-10, tlr-2, etc. There was a significant elevation in the expression of all these genes compared to control and fish treated with BMSL or cN16E alone. Interestingly, when the rescued zebrafish were reinfected with the same pathogen, the levels of expression of these genes were many folds higher than seen earlier. Radial immune diffusion analyses (RIA) using zebrafish serum revealed antibody production during the initial infection and treatment. Interestingly, reinfected fish had significant immunoprecipitation in RIA, a feature absent in the groups treated with cN16E, BMSL, and control. These results clearly show that the BcN16E complex not only rescued infected zebrafish but also conferred long-lasting protection in terms of immunomodulation that protects against multiple reinfections. The findings support that BcN16E has immense potential as a novel immunostimulant for various biomedical applications.

Diabetes mellitus, systemic inflammation and overactive bladder

Background

Increasing evidence emphasizes the potential relationship between diabetes and OAB (overactive bladder). However, large population epidemiology is still lacking.

Methods

This cross-sectional study included six cycle NHANES surveys, with a total of 23863 participants. Logistic regression models were constructed to analyze the association between diabetes mellitus, diabetes-related markers, and inflammatory biomarkers with OAB. Restricted cubic splines were used to analyze the non-linear associations. Mediating analysis was performed to test the effect of inflammatory biomarkers on the relationship between diabetes-related markers and OAB. Finally, machine learning models were applied to predict the relative importance and construct the best-fit model.

Results

Diabetes mellitus participants' OAB prevalence increased by 77% compared with non-diabetes. As the quartiles of diabetes-related markers increased, the odds of OAB monotonically increased in three models (all p for trend < 0.001). Glycohemoglobin exhibited a linear association with OAB (p for nonlinearity > 0.05). White blood cells significantly mediated the associations between diabetes-related markers (glycohemoglobin, fasting glucose, and insulin) with OAB, and the proportions were 7.23%, 8.08%, and 17.74%, respectively (all p < 0.0001). Neutrophils partly mediated the correlation between (glycohemoglobin, fasting glucose, and insulin) and OAB at 6.58%, 9.64%, and 17.93%, respectively (all p < 0.0001). Machine learning of the XGBoost model constructs the best fit model, and XGBoost predicts glycohemoglobin is the most important indicator on OAB.

Conclusion

Our research revealed diabetes mellitus and diabetes-related markers were remarkably associated with OAB, and systemic inflammation was an important mediator of this association.

Role of some inflammasomes in rheumatoid arthritis patients in Egypt

AIM

This study aims to demonstrate the role of some inflammasomes genes: NLRC4 (the NLR family, CARD domain-containing protein 4), NLRP1 (NLR family, pyrin domain-containing 1), ASC (Apoptosis-associated speck-like protein containing a CARD), and CASPASE-1 in the pathogenesis of Rheumatoid arthritis (RA) in Egyptian population.

MAIN METHODS

The expression level of NLRC4, NLRP1, ASC, and CASPASE-1 within PBMCs isolated from all RA subjects by quantitative real-time PCR. GAPDH gene was used as a reference gene. Measurement of serum level of IL-1β and IL-18 was performed using ELISA.

KEY FINDINGS

Results showed dysregulated inflammasomes expression that may participate in the pathogenesis of the inflammatory process of the disease.

SIGNIFICANCE

Understanding the role of inflammasomes in RA pathogenesis helps in finding promising therapy for the treatment and management of this disease.

The Role of NLRP3 in Regulation of Antimicrobial Peptides and Estrogen Signaling in UPEC-Infected Bladder Epithelial Cells

The NLRP3 inflammasome, estrogen and antimicrobial peptides have all been found to have a vital role in the protection of the bladder urothelium. However, the interdependence between these protective factors during a bladder infection is currently unknown. Our aim was to investigate the role of NLRP3 in the regulation of antimicrobial peptides and estrogen signaling in bladder epithelial cells during a UPEC infection. Human bladder epithelial cells and CRISPR/Cas9-generated NLRP3-deficient cells were stimulated with the UPEC strain CFT073 and estradiol. The gene and protein expression were evaluated with microarray, qRT-PCR, western blot and ELISA. Microarray results showed that the expression of most antimicrobial peptides was reduced in CFT073-infected NLRP3-deficient cells compared to Cas9 control cells. Conditioned medium from NLRP3-deficient cells also lost the ability to suppress CFT073 growth. Moreover, NLRP3-deficient cells had lower basal release of Beta-defensin-1, Beta-defensin-2 and RNase7. The ability of estradiol to induce an increased expression of antimicrobial peptides was also abrogated in NLRP3-deficient cells. The decreased antimicrobial peptide expression might be linked to the observed reduced expression and activity of estradiol receptor beta in NLRP3-deficient cells. This study suggests that NLRP3 may regulate the release and expression of antimicrobial peptides and affect estrogen signaling in bladder epithelial cells.

TRAF6-TAK1-IKKβ pathway mediates TLR2 agonists activating "one-step" NLRP3 inflammasome in human monocytes

Gram-positive bacterial infection causes high morbidity and mortality worldwide, while the underlying mechanism for host sensing bacterial components and initiating immune responses remains elusive. The NLRP3 inflammasome is a cytosolic multi-protein complex sensing a broad spectrum of endogenous danger signals and environmental irritants. In contrast to canonical NLRP3 inflammasome activation that needs both priming and activation signals, Lipopolysaccharide (LPS) from gram-negative bacteria activates the "one-step" NLRP3 inflammasome in human monocytes, which relies on the TLR4-TRIF-Caspase-8 signaling. Here, we show that in human monocytes, TLR2 agonists such as heat-killed gram-positive bacteria, peptidoglycan (PGN) or synthetic bacterial lipoprotein analog Pam3CysSerLys4 (Pam3CSK4) are able to induce the "one-step" NLRP3 inflammasome activation. Using genetic targeting and pharmacological inhibition approaches, it was found that TLR2 propagates signal through TRAF6, TAK1 and IKKβ, ultimately activated NLRP3 independent of RelA. In addition, IKKβ interacts with NLRP3 directly and affects NLRP3 inflammasome activation. These results reveal the signaling cascade downstream of TLR2 upon sensing gram-positive bacterial infection and activating the "one-step" NLRP3 inflammasome in human monocytes, which provides clue for controlling gram-positive bacterial infection-related inflammation.

Inflammation triggered by the NLRP3 inflammasome is a critical driver of diabetic bladder dysfunction

Diabetes is a rapidly expanding epidemic projected to affect as many as 1 in 3 Americans by 2050. This disease is characterized by devastating complications brought about high glucose and metabolic derangement. The most common of these complications is diabetic bladder dysfunction (DBD) and estimates suggest that 50-80% of patients experience this disorder. Unfortunately, the Epidemiology of Diabetes Interventions and Complications Study suggests that strict glucose control does not decrease ones risk for incontinence, although it does decrease the risk of other complications such as retinopathy, nephropathy and neuropathy. Thus, there is a significant unmet need to better understand DBD in order to develop targeted therapies to alleviate patient suffering. Recently, the research community has come to understand that diabetes produces a systemic state of low-level inflammation known as meta-inflammation and attention has focused on a role for the sterile inflammation-inducing structure known as the NLRP3 inflammasome. In this review, we will examine the evidence that NLRP3 plays a central role in inducing DBD and driving its progression towards an underactive phenotype.

TREM2/β-catenin attenuates NLRP3 inflammasome-mediated macrophage pyroptosis to promote bacterial clearance of pyogenic bacteria

Triggering receptors expressed on myeloid cells 2 (TREM2) is considered a protective factor to protect host from bacterial infection, while how it elicits this role is unclear. In the present study, we demonstrate that deficiency of triggering receptors expressed on myeloid cells 2 (TREM2) significantly enhanced macrophage pyroptosis induced by four common pyogenic bacteria including Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus pneumoniae, and Escherichia coli. TREM2 deficiency also decreased bacterial killing ratio of macrophage, while Caspase-1 or GSDMD inhibition promoted macrophage-mediated clearance to these bacteria. Further study demonstrated that the effect of TREM2 on macrophage pyroptosis and bacterial eradication mainly dependents on the activated status of NLRP3 inflammasome. Moreover, as the key downstream of TREM2, β-catenin phosphorylated at Ser675 by TREM2 signal and accumulated in nucleus and cytoplasm. β-catenin mediated the effect of TREM2 on NLRP3 inflammasome and macrophage pyroptosis by reducing NLRP3 expression, and inhibiting inflammasome complex assembly by interacting with ASC. Collectively, TREM2/β-catenin inhibits NLRP3 inflammasome to regulate macrophage pyroptosis, and enhances macrophage-mediated pyogenic bacterial clearance.

The Role of Inflammasomes in Mediating Urological Disease: A Short Literature Review

Inflammasome dysfunction may be responsible for underlying inflammatory diseases, which include renal and urological pathologies. Five inflammasomes have been described, including nucleotide-binding domain leucine-rich repeat (NLR), NL pyrin domain containing receptor 1(NLPR1), NLRP3, NLR and caspase recruitment domain containing receptor 4 (NLRC4), and the AIM2-like receptor. The purpose of this study was to review literature sources regarding how innate immunity and inflammasomes contribute to urologic disease and infection. A literature search of PubMed/MEDLINE, EMBASE and Google Scholar articles. Articles were selected for review if their content included (1) inflammasomes and (2) urology in the adult population. The initiation of specific cytokine cascades, which include IL-1β and IL-18, appear responsible for a repertoire of urologic pathologies. Inflammation mediates a wide range of uropathies (urologic disorders and infections) which are found in the bladder, prostate, or kidney and inflammasomes appear to be particularly responsible for urological and renal pathologies. Understanding the role of inflammasomes in urologic disorders can help improve treatment and overall quality of life in patients with these disorders.

Flavonoid Nobiletin Attenuates Cyclophosphamide-Induced Cystitis in Mice through Mechanisms That Involve Inhibition of IL-1β Induced Connexin 43 Upregulation and Gap Junction Communication in Urothelial Cells

Bladder inflammatory diseases cause various urinary symptoms, such as urinary frequency and painful urination, that impair quality of life. In this study, we used a mouse model of cyclophosphamide (CYP)-induced bladder inflammation and immortalized human urothelial (TRT-HU1) cells to explore the preventive potential of nobiletin (NOB), a polymethoxylated flavone enriched in citrus fruit peel, and investigate its mechanism of action in the bladder. Prophylaxis with PMF90 (60% NOB) attenuated the development of bladder inflammation and urinary symptoms in CYP-treated mice. PMF90 also reduced the upregulation of connexin 43 (Cx43), a major component of gap junction channels, in the bladder mucosa of CYP-treated mice. Stimulation of TRT-HU1 cells with the pro-inflammatory cytokine IL-1β increased Cx43 mRNA and protein expression and enhanced gap junction coupling-responses that were prevented by pre-treatment with NOB. In urothelium-specific Cx43 knockout (uCx43KO) mice, macroscopic signs of bladder inflammation and changes in voiding behavior induced by CYP treatment were significantly attenuated when compared to controls. These findings indicate the participation of urothelial Cx43 in the development of bladder inflammation and urinary symptoms in CYP-treated mice and provide pre-clinical evidence for the preventive potential of NOB through its anti-inflammatory effects on IL-1β signaling and urothelial Cx43 expression.

Specialized pro-resolution mediators in the bladder: Receptor expression and recovery of bladder function from cystitis

Inflammation is a central process in most benign bladder disorders, and its control is a delicate balance between initiating factors and resolving factors. While recent discoveries have shown a central role for the NLRP3 inflammasome in initiation, the resolving pathways remain unexplored. Resolution is controlled by specialized pro-resolution mediators (SPMs) functioning through seven receptors (six in rodents). Here we demonstrate expression of all seven in humans (six in mice) through immunocytochemistry. Expression was universal in urothelia with most also expressed in smooth muscle. We next explored the therapeutic potential of three SPMs; Resolvin E1 (RvE1), Maresin 1 (MaR1), and Protectin D1 (PD1). SPMs promote epithelial wound/barrier repair and RvE1 triggered dose-dependent wound closure in urothelia in vitro (scratch assay) (EC90 = 12.5 nM). MaR1 and PD1 were equally effective at this concentration. In vivo analyses employed a cyclophosphamide (CP) model of bladder inflammation (Day 0-CP [150 mg/kg], Day 1 to 3 SPM [25 µg/kg/day], Day 4 - analysis). All three SPMs reduced bladder inflammation (Evans blue) and bladder weights to control levels. Effects of RvE1 were also examined by urodynamics. CP decreased void volume, increased frequency and decreased bladder capacity while RvE1 restored values to control levels. Finally, SPMs reduce fibrosis and RvE1 reduced urothelial expression of TGF-β and collagen I to control values. Together these results expand the known SPMs active in the bladder tissue and provide promising therapeutic targets for controlling inflammation in a wide variety of inflammation-associated benign bladder diseases.

The role of caspase-1, caspase-4 and NLRP3 in regulating the host cell response evoked by uropathogenic Escherichia coli

The inflammasome-associated proteins caspase-1, caspase-4 and NLRP3 have been emphasised to be essential in the host cell response during urinary tract infection (UTI) by regulating IL-1β release. Our aim was to investigate how the inflammasome-associated proteins regulate the cell response of bladder epithelial cells during infection with uropathogenic Escherichia coli (UPEC). Human bladder epithelial cells (5637) and CRISPR/Cas9 generated caspase-1, caspase-4 and NLRP3 knockdown cells were stimulated with the UPEC strain CFT073. Using Olink proteomics and real time RT-PCR, we showed that caspase-1, caspase-4 and NLRP3 are vital for the expression of many inflammatory genes and proteins from bladder epithelial cells. When investigating the effect of inflammasome-associated proteins on neutrophils, we found that conditioned medium from UPEC-infected caspase-4 knockdown cells significantly increased phagocytosis of CFT073 and significantly decreased ROS production from neutrophils. In contrast, conditioned medium from UPEC-infected NLRP3 knockdown cells significantly decreased the phagocytosis of CFT073 and significantly increased the ROS production from neutrophils. In conclusion, we showed that the inflammasome-associated proteins contribute to the host cell response during UPEC infection.

Human Renal Fibroblasts, but Not Renal Epithelial Cells, Induce IL-1β Release during a Uropathogenic Escherichia coli Infection In Vitro

Understanding how uropathogenic Escherichia coli (UPEC) modulates the immune response in the kidney is essential to prevent UPEC from reaching the bloodstream and causing urosepsis. The purpose of this study was to elucidate if renal fibroblasts can release IL-1β during a UPEC infection and to investigate the mechanism behind the IL-1β release. We found that the UPEC strain CFT073 induced an increased IL-1β and LDH release from renal fibroblasts, but not from renal epithelial cells. The UPEC-induced IL-1β release was found to be NLRP3, caspase-1, caspase-4, ERK 1/2, cathepsin B and serine protease dependent in renal fibroblasts. We also found that the UPEC virulence factor α-hemolysin was necessary for IL-1β release. Conditioned medium from caspase-1, caspase-4 and NLRP3-deficient renal fibroblasts mediated an increased reactive oxygen species production from neutrophils, but reduced UPEC phagocytosis. Taken together, our study demonstrates that renal fibroblasts, but not renal epithelial cells, release IL-1β during a UPEC infection. This suggest that renal fibroblasts are vital immunoreactive cells and not only structural cells that produce and regulate the extracellular matrix.

DDX17 is an essential mediator of sterile NLRC4 inflammasome activation by retrotransposon RNAs

Detection of microbial products by multiprotein complexes known as inflammasomes is pivotal to host defense against pathogens. Nucleotide-binding domain leucine-rich repeat (NLR) CARD domain containing 4 (NLRC4) forms an inflammasome in response to bacterial products; this requires their detection by NLR family apoptosis inhibitory proteins (NAIPs), with which NLRC4 physically associates. However, the mechanisms underlying sterile NLRC4 inflammasome activation, which is implicated in chronic noninfectious diseases, remain unknown. Here, we report that endogenous short interspersed nuclear element (SINE) RNAs, which promote atrophic macular degeneration (AMD) and systemic lupus erythematosus (SLE), induce NLRC4 inflammasome activation independent of NAIPs. We identify DDX17, a DExD/H box RNA helicase, as the sensor of SINE RNAs that licenses assembly of an inflammasome comprising NLRC4, NLR pyrin domain–containing protein 3, and apoptosis-associated speck-like protein–containing CARD and induces caspase-1 activation and cytokine release. Inhibiting DDX17-mediated NLRC4 inflammasome activation decreased interleukin-18 release in peripheral blood mononuclear cells of patients with SLE and prevented retinal degeneration in an animal model of AMD. Our findings uncover a previously unrecognized noncanonical NLRC4 inflammasome activated by endogenous retrotransposons and provide potential therapeutic targets for SINE RNA–driven diseases.

Regulation of the Immune Microenvironment by an NLRP3 Inhibitor Contributes to Attenuation of Acute Right Ventricular Failure in Rats with Pulmonary Arterial Hypertension

Background

Right heart failure is the terminal stage of PAH. When PAH patients suffer from pulmonary infection or puerperal infection heart failure often rapidly develops. Low dose of lipopolysaccharide induces rapid right ventricular failure in rats with pulmonary arterial hypertension.

Purpose

The objective of this study was to investigate whether the NLRP3 inflammasome mediates disturbance of the ventricular immune microenvironment of PAH rats and promotes right ventricular failure.

Methods

Intraperitoneal injection of monocrotaline was used to induce PAH in rats. Right ventricular function was measured via echocardiography before and after the rats were treated with lipopolysaccharide and MCC950. The degree of immune microenvironment disturbance in right ventricular tissue was measured with a rat chemokine and cytokine antibody array, Western blot, flow cytometry and quantitative real-time PCR analysis.

Results

After the rats were injected with LPS, they exhibited right ventricular dysfunction and a significant increase in right ventricular tissue inflammation with elevated M1 macrophage proportion. Administration of MCC950 suppressed inflammation and improved right ventricular function. The number of M1 macrophages was decreased after MCC950 treatment. NLRP3 inflammasome inhibition ameliorated LPS-induced changes in the immune microenvironment in the right heart and right ventricular dysfunction in rats with PAH.

Conclusion

Selective inhibition of NLRP3 pathway interfered the interaction between hypertrophic cardiomyocytes and macrophages in the initial stage of inflammation and maintained the immune microenvironment balance, eventually contributing to attenuation of LPS-induced acute heart failure in PAH rats.

Targeting of Uropathogenic Escherichia coli papG gene using CRISPR-dot nanocomplex reduced virulence of UPEC

Urinary tract infections (UTI) are the most common infectious diseases in the world. It is becoming increasingly tough to treat because of emergence of antibiotic resistance. So, there is an exigency to develop novel anti-virulence therapeutics to combat multi-drug resistance pathogenic strains. Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) discovery has revolutionized the gene editing technology for targeted approach. The greatest obstacle for CRISPR/Cas9 is cargo delivery systems and both viral and plasmid methods have disadvantages. Here, we report a highly efficient novel CRISPR based gene editing strategy, CRISPR-dots for targeting virulence factor Fimbrial Adhesion (papG gene), the bacterial adhesion molecule. Carbon quantum dots (CQD) were used as a delivery vehicle for Cas9 and gRNA into CFT073, a UPEC strain. CQDs were covalently conjugated to cas9 and papG-targeted guide RNA (gRNA) forming a nanocomplex CRISPR-dots (Cri-dots) as confirmed by DLS and transmission electron microscopy. Cri-dots-papG significantly targeted papG as demonstrated by decrease in the expression of papG.Further papG deficient UPEC had significantly reduced adherence ability and biofilm forming ability as demonstrated by fluorescence microscopy and scanning electron microscopy. Also, papG deficient UPEC had reduced virulence as shown by significantly increased survival of Caenorhabditis elegans (C. elegans) worms compared to UPEC. Our findings suggest that targeting of papG gene using Cri-dots nanocomplexes significantly reduced the pathogenicity of UPEC. Thus, Cri-dots nanocomplex offer a novel anti-bacterial strategy against multi-drug resistant UPEC.

A novel RIP1/RIP3 dual inhibitor promoted OPC survival and myelination in a rat neonatal white matter injury model with hOPC graft

Background

The dual inhibitors of receptor interacting protein kinase-1 and -3 (RIP1 and RIP3) play an important role in cell death processes and inflammatory responses. White matter injury (WMI), a leading cause of neurodevelopmental disabilities in preterm infants, which is characterized by extensive myelination disturbances and demyelination. Neuroinflammation, leads to the loss and differentiation-inhibition of oligodendrocyte precursor cells (OPCs), represents a major barrier to myelin repair. Whether the novel RIP1/RIP3 dual inhibitor ZJU-37 can promote transplanted OPCs derived from human neural stem cells (hOPCs) survival, differentiation and myelination remains unclear. In this study, we investigated the effect of ZJU-37 on myelination and neurobehavioral function in a neonatal rat WMI model induced by hypoxia and ischemia.

Methods

In vivo, P3 rat pups were subjected to right common carotid artery ligation and hypoxia, and then treated with ZJU-37 or/and hOPCs, then OPCs apoptosis, myelination, glial cell and NLRP3 inflammasome activation together with cognitive outcome were evaluated at 12 weeks after transplantation. In vitro, the effect of ZJU-37 on NLRP3 inflammasome activation in astrocytes induced by oxygen–glucose deprivation (OGD) were examined by western blot and immunofluorescence. The effect of ZJU-37 on OPCs apoptosis induced by the conditioned medium from OGD-injured astrocytes (OGD-astrocyte-CM) was analyzed by flow cytometry and immunofluorescence.

Results

ZJU-37 combined with hOPCs more effectively decreased OPC apoptosis, promoted myelination in the corpus callosum and improved behavioral function compared to ZJU-37 or hOPCs treatment. In addition, the activation of glial cells and NLRP3 inflammasome was reduced by ZJU-37 or/and hOPCs treatment in the neonatal rat WMI model. In vitro, it was also confirmed that ZJU-37 can suppress NLRP3 inflammasome activation in astrocytes induced by OGD. Not only that, the OGD-astrocyte-CM treated with ZJU-37 obviously attenuated OPC apoptosis and dysdifferentiation caused by the OGD-astrocyte-CM.

Conclusions

The novel RIP1/RIP3 dual inhibitor ZJU-37 may promote OPC survival, differentiation and myelination by inhibiting NLRP3 inflammasome activation in a neonatal rat model of WMI with hOPC graft.

The microbiome and host mucosal interactions in urinary tract diseases

The urinary tract consists of the bladder, ureters, and kidneys, and is an essential organ system for filtration and excretion of waste products and maintaining systemic homeostasis. In this capacity, the urinary tract is impacted by its interactions with other mucosal sites, including the genitourinary and gastrointestinal systems. Each of these sites harbors diverse ecosystems of microbes termed the microbiota, that regulates complex interactions with the local and systemic immune system. It remains unclear whether changes in the microbiota and associated metabolites may be a consequence or a driver of urinary tract diseases. Here, we review the current literature, investigating the impact of the microbiota on the urinary tract in homeostasis and disease including urinary stones, acute kidney injury, chronic kidney disease, and urinary tract infection. We propose new avenues for exploration of the urinary microbiome using emerging technology and discuss the potential of microbiome-based medicine for urinary tract conditions.

Uropathogenic Escherichia coli in India-an Overview on Recent Research Advancements and Trends

Urinary tract infection (UTI), a prevalent disease in India, also ranks among the most common infections in developing countries. The rapid emergence of antibiotic-resistant uropathogenic Escherichia coli (UPECs), the leading etiologic agent of UTI, in the last few years, led to an upsurge in the health care cost. This caused a considerable economic burden, especially in low-middle income country, India. This review aimed to provide an explicit overview of the recent advancements in E. coli-mediated UTI in India by incorporation of valuable information from the works published in PubMed and Google Scholar in the last six years (2015 to August, 2020). The literature survey demonstrated UPECs as the most predominant uropathogen in India, especially among females, causing both asymptomatic bacteriuria (ABU) and symptomatic UTI. An overall increasing national trend in resistance to penicillins, cephalosporins, aminoglycosides, fluoroquinolones, and sulfonamides was perceived irrespective of ABU and symptomatic UPECs during the aforementioned study period. High incidences of multidrug resistance, extended-spectrum β-lactamases, metallo β-lactamases, and AmpCs in UPECs were reported. Notable information on the pathogenic profiles, phylogroups, pathogenicity islands, and evidence of pathoadaptive FimH mutations was described. Alternative therapeutics and potential drug targets against UPECs were also reconnoitered. Therefore, the nationwide widespread occurrences of highly virulent MDR UPEC together with the limited availability of therapeutics highlighted the urgent need for promotion and invention of alternative therapeutics, search for which had already been started. Moreover, investigation of several mechanisms of UPEC infection and the search for potential drug targets might help to design newer therapeutics.

Cannabinoids as Key Regulators of Inflammasome Signaling: A Current Perspective

Inflammasomes are cytoplasmic inflammatory signaling protein complexes that detect microbial materials, sterile inflammatory insults, and certain host-derived elements. Inflammasomes, once activated, promote caspase-1–mediated maturation and secretion of pro-inflammatory cytokines, interleukin (IL)-1β and IL-18, leading to pyroptosis. Current advances in inflammasome research support their involvement in the development of chronic inflammatory disorders in contrast to their role in regulating innate immunity. Cannabis (marijuana) is a natural product obtained from the Cannabis sativa plant, and pharmacologically active ingredients of the plant are referred to as cannabinoids. Cannabinoids and cannabis extracts have recently emerged as promising novel drugs for chronic medical conditions. Growing evidence indicates the potent anti-inflammatory potential of cannabinoids, especially Δ⁹-tetrahydrocannabinol (Δ⁹-THC), cannabidiol (CBD), and synthetic cannabinoids; however, the mechanisms remain unclear. Several attempts have been made to decipher the role of cannabinoids in modulating inflammasome signaling in the etiology of chronic inflammatory diseases. In this review, we discuss recently published evidence on the effect of cannabinoids on inflammasome signaling. We also discuss the contribution of various cannabinoids in human diseases concerning inflammasome regulation. Lastly, in the milieu of coronavirus disease-2019 (COVID-19) pandemic, we confer available evidence linking inflammasome activation to the pathophysiology of COVID-19 suggesting overall, the importance of cannabinoids as possible drugs to target inflammasome activation in or to support the treatment of a variety of human disorders including COVID-19.

Activation of NLRP3 by uropathogenic Escherichia coli is associated with IL-1β release and regulation of antimicrobial properties in human neutrophils

The NLRP3 inflammasome and IL-1β have recently been linked to the severity of uropathogenic Escherichia coli (UPEC)-mediated urinary tract infection (UTI). However, not much is known about the contribution of NLRP3 to the antimicrobial properties of neutrophils and the release of IL-1β during UPEC infection. The purpose of this study was to elucidate the mechanisms behind UPEC-induced IL-1β release from human neutrophils, and to investigate the contribution of the NLRP3 inflammasome in neutrophil-mediated inhibition of UPEC growth. We found that the UPEC strain CFT073 increased the expression of NLRP3 and increased caspase-1 activation and IL-1β release from human neutrophils. The IL-1β release was mediated by the NLRP3 inflammasome and by serine proteases in an NF-κB-and cathepsin B-dependent manner. The UPEC virulence factors α-hemolysin, type-1 fimbriae and p-fimbriae were all shown to contribute to UPEC mediated IL-1β release from neutrophils. Furthermore, inhibition of caspase-1 and NLRP3 activation increased neutrophil ROS-production, phagocytosis and the ability of neutrophils to suppress UPEC growth. In conclusion, this study demonstrates that UPEC can induce NLRP3 and serine protease-dependent release of IL-1β from human neutrophils and that NLRP3 and caspase-1 can regulate the antimicrobial activity of human neutrophils against UPEC.

Interplays between inflammasomes and viruses, bacteria (pathogenic and probiotic), yeasts and parasites

In recent years, scientists studying the molecular mechanisms of inflammation have discovered an amazing phenomenon - the inflammasome - a component of the innate immune system that can regulate the functional activity of effector cells during inflammation. At present, it is known that inflammasomes are multimolecular complexes (cytosolic multiprotein oligomers of the innate immune system) that contain many copies of receptors recognizing the molecular structures of cell-damaging factors and pathogenic agents. Inflammasomes are mainly formed in myeloid cells, and their main function is participation in the cleavage of the pro-IL-1β and pro-IL-18 cytokines into their biologically active forms (IL-1β, IL-18). Each type of microorganism influences particular inflammasome activation, and long-term exposure of the organism to viruses, bacteria, yeasts or parasites, among others, can induce uncontrolled inflammation and autoinflammatory diseases. Therefore, this review aims to present the most current scientific data on the molecular interplay between inflammasomes and particular microorganisms. Knowledge about the mechanisms responsible for the interaction between the host and certain types of microorganisms could contribute to the individuation of innovative strategies for the treatment of uncontrolled inflammation targeting a specific type of inflammasome activated by a specific type of pathogen.

α-Hemolysin of uropathogenic E. coli regulates NLRP3 inflammasome activation and mitochondrial dysfunction in THP-1 macrophages

Hemolysin expressing UPEC strains have been associated with severe advanced kidney pathologies, such as cystitis and pyelonephritis, which are associated with an inflammatory response. Macrophages play an important role in regulating an inflammatory response during a urinary tract infection. We have studied the role of purified recombinant α-hemolysin in inducing inflammatory responses and cell death in macrophages. Acylation at lysine residues through HlyC is known to activate proHlyA into a fully functional pore-forming toxin, HlyA. It was observed that active α-hemolysin (HlyA) induced cleavage of caspase-1 leading to the maturation of IL-1β, while inactive α-hemolysin (proHlyA) failed to do so in THP-1 derived macrophages. HlyA also promotes deubiquitination, oligomerization, and activation of the NLRP3 inflammasome, which was found to be dependent on potassium efflux. We have also observed the co-localization of NLRP3 within mitochondria during HlyA stimulations. Moreover, blocking of potassium efflux improved the mitochondrial health in addition to a decreased inflammatory response. Our study demonstrates that HlyA stimulation caused perturbance in potassium homeostasis, which led to the mitochondrial dysfunction followed by an acute inflammatory response, resulting in cell death. However, the repletion of intracellular potassium stores could avoid HlyA induced macrophage cell death. The findings of this study will help to understand the mechanism of α-hemolysin induced inflammatory response and cell death.

Mechanism of blood-brain barrier disruption by an Escherichia coli from lambs with severe diarrhea and meningoencephalitis

Escherichia coli (E. coli) is a common conditional pathogen that is associated with a variety of infections in humans and animals. Although there are increasing reports regarding the infection of E. coli to domestic animals and poultry, the infection of E. coli in lambs is relatively less reported, especially on meningoencephalitis. Here, we reported the isolation of an E. coli strain designated as NMGCF-19 from lambs characterized with severe diarrhea and neurological disorder, and demonstrated that NMGCF-19 as the causative agent has the ability to disrupt the blood-brain barrier (BBB) to cause the meningoencephalitis using a mouse model. Investigation on the mechanism regarding the NMGCF-19-related meningoencephalitis revealed a significant decreased expression of ZO-1 and occludin in mouse brain tissue in comparison with the control mice. Moreover, infection of NMGCF-19 increased the expression of proinflammatory cytokines TNF-α, IL-6, IL-1β and IL-18, up-regulated HMGB1 level, and activated TLR2/TLR4/MyD88 and NLRP3 inflammasome pathways. These findings indicated that NMGCF-19 likely invades the brain tissue by disrupting the tight junction (TJ) architecture and causes the meningoencephalitis via increasing inflammatory response and activating TLR2/TLR4/MyD88 and NLRP3 inflammasome pathways.