Experimental model for acute kidney injury caused by uropathogenic Escherichia coli

Small Extracellular Vesicles from Myeloid-derived Suppressor Cells: A Promoter of Escherichia Coli-induced Acute Kidney Injury

Acute kidney injury (AKI) during Escherichia coli (E. coli) infection presents significant clinical challenges, with evidence suggesting small extracellular vesicles (sEVs) drived miRNAs play a key role in its pathogenesis. This study investigated the impact of sEVs drived miR-128-3p from myeloid-derived suppressor cells (MDSCs) on AKI onset during E. coli infection. Using a rat model induced by transurethral inoculation with a virulent E. coli strain, AKI severity was assessed by measuring blood urea nitrogen (BUN) and serum creatinine (SCr). Mass cytometry evaluated immune cell composition in renal tissues, and pro-inflammatory markers (E-selectin, ICAM1, IL-12, IL-10, p-p65, IκB) were quantified. SEVs were isolated through differential centrifugation and characterized by transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA). The role of sEVs was further examined by inhibiting their production in vitro with GW4869. High-throughput sequencing identified differentially expressed miRNAs, with qRT-PCR confirming elevated miR-128-3p in AKI samples. Results showed that MDSC accumulation during E. coli infection increased exosome release and upregulated miR-128-3p. This miRNA exacerbated AKI by promoting endothelial inflammation and activating the NF-κB pathway. These findings underscore MDSC-derived sEVs drived miR-128-3p as a mechanistic driver in AKI and a potential diagnostic and therapeutic target for E. coli-induced AKI.

Investigation of the Optimum Preparation of Peach Gum Polysaccharides and the In Vivo and In Vitro Therapeutic Effects on Acute Pyelonephritis

BACKGROUND

Acute pyelonephritis (APN), known as stranguria in traditional Chinese medicine, is commonly treated with antibiotics. However, the rise in antibiotic resistance and the high rates of recurrence of APN make its treatment complicated, thus the development of alternative therapies is critical. Peach gum has long been recognized by traditional Chinese medicine as a food with medicinal value of relieving stranguria, but whether and how its primary constituent peach gum polysaccharides (PGPs) contribute to the diuretic function is still not clear.

PURPOSE

The aim of this study was to investigate the optimum extraction process of PGPs and to evaluate its therapeutic effect on APN rats and to discover the underlying mechanism.

METHODS

In this study, surface design optimization was adopted to optimize the preparation of PGPs and HPLC and FT-IR spectra were used to evaluate the quality of PGPs; APN model rat was established by the Escherichia coli urinary tract infection method; the therapeutic effect and mechanism of PGPs on APN were determined by the visceral index, biochemical indicators, pathological section of the APN rat, and diuretic activity on mice and antibacterial activity in vitro.

RESULTS

Compared with an untreated APN group, the results showed that treatment with PGPs increased the APN-induced attenuation of secretory immunoglobulin A (sIgA) and creatinine clearance and decreased the APN-induced enhancement of the number of white blood cell (WBC), neutrophil counts (NC), bacteria load of the kidneys, kidney index, serum creatinine, urine volume, blood urea nitrogen (BUN), and interleukin-2 (IL-2) levels. The mechanism underlying these effects was further elucidated through in vitro experiments of the antibacterial and antiadhesion effects of PGPs.

CONCLUSION

Due to the good therapeutic effects and advantages of PGPs, it could be considered as an alternative medicine to treat APN.

Genotoxic Escherichia coli Strains Encoding Colibactin, Cytolethal Distending Toxin, and Cytotoxic Necrotizing Factor in Laboratory Rats

Although many Escherichia coli strains are considered commensals in mammals, strains encoding the cyclomodulin genotoxins are associated with clinical and subclinical disease in the urogenital and gastrointestinal tracts, meningitis, and inflammatory disorders. These genotoxins include the polyketide synthase (pks) pathogenicity island, cytolethal distending toxin (cdt), and hemolysin-associated cytotoxic necrotizing factor (cnf). E. coli strains are not excluded from rodents housed under SPF conditions in academic or vendor facilities. This study isolated and characterized genotoxin-encoding E. coli from laboratory rats obtained from 4 academic institutions and 3 vendors. A total of 69 distinct E. coli isolates were cultured from feces, rectal swab, nares, or vaginal swab of 52 rats and characterized biochemically. PCR analysis for cyclomodulin genes and phylogroup was performed on all 69 isolates. Of the 69 isolates, 45 (65%) were positive for pks, 20/69 (29%) were positive for cdt, and 4 (6%) were positive for cnf. Colibactin was the sole genotoxin identified in 21 of 45 pks+ isolates (47%), whereas cdt or cnf was also present in the remaining 24 isolates (53%); cdt and cnf were never present together or without pks. All genotoxin-associated strains were members of pathogen-associated phylogroup B2. Fisher exact and χ² tests demonstrated significant differences in genotoxin prevalence and API code distribution with regard to vendor. Select E. coli isolates were characterized by HeLa cell in vitro cytotoxicity assays, serotyped, and whole-genome sequenced. All isolates encoding cyclomodulins induced megalocytosis. Serotypes corresponded with vendor origin and cyclomodulin composition, with the cnf+ serotype representing a known human uropathogen. Whole-genome sequencing confirmed the presence of complete pks, cdt, and hemolysin-cnf pathogenicity islands. These findings indicate that genotoxin-encoding E. coli colonize laboratory rats from multiple commercial vendors and academic institutions and suggest the potential to contribute to clinical disease and introduce confounding variables into experimental rat models.

Microbial stability of syringes of anesthetic drugs prepared in the operating room

STUDY OBJECTIVE

To determine whether microbial contamination of anesthesia syringes prepared in the operating room (OR) become contaminated in a time-dependent fashion.

DESIGN

Observational.

SETTING

Operating suite in a major university hospital.

PATIENTS

None (in vitro study). 400 syringes were studied for microbial contamination.

INTERVENTIONS

Syringes prepared in the OR by anesthesia personnel were sampled at 1, 2, 3, or 4 h in a sterile fashion and sent to the microbiology laboratory for quantitative culture of any bacteria.

MEASUREMENTS

Colony forming units (CFU) per mL of drug were calculated and any identified positive cultures were identified by Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry. Logistic regression was used to test the effect of time since preparation on prevalence of positive culture, as was the effect of number of accesses of the syringe and identity of the drug.

MAIN RESULTS

Overall, 9/400 (2.25%) syringes were positive for bacteria. The median (interquartile range [IQR]) concentration of bacteria among positive cultures was 100 (100,100) CFU. All cultured species were generally nonpathogenic common contaminants. There was no effect of time since preparation, number of accesses of the syringe at the time of sampling, or drug identity (propofol vs. other).

CONCLUSIONS

Contamination of anesthesia syringes is uncommon and occurs at a low overall concentration of bacteria. Contamination does not appear to be time related, and thus calls into question the reasonableness of USP Chapter 797's one-hour requirement.