Antibiotic-induced intestinal microbiota depletion can attenuate the acute kidney injury to chronic kidney disease transition via NADPH oxidase 2 and trimethylamine-N-oxide inhibition.

Intestinal microbiota and their metabolites affect systemic inflammation and kidney disease outcomes. Here, we investigated the key metabolites associated with the acute kidney injury (AKI)-to chronic kidney disease (CKD) transition and the effect of antibiotic-induced microbiota depletion (AIMD) on this transition. In 61 patients with AKI, 59 plasma metabolites were assessed to determine the risk of AKI-to-CKD transition. An AKI-to-CKD transition murine model was established four weeks after unilateral ischemia-reperfusion injury (IRI) to determine the effects of AIMD on the gut microbiome, metabolites, and pathological responses related to CKD transition. Human proximal tubular epithelial cells were challenged with CKD transition-related metabolites, and inhibitory effects of NADPH oxidase 2 (NOX2) signals were tested. Based on clinical metabolomics, plasma trimethylamine N-oxide (TMAO) was associated with a significantly increased risk for AKI-to-CKD transition [adjusted odds ratio 4.389 (95% confidence interval 1.106-17.416)]. In vivo, AIMD inhibited a unilateral IRI-induced increase in TMAO, along with a decrease in apoptosis, inflammation, and fibrosis. The expression of NOX2 and oxidative stress decreased after AIMD. In vitro, TMAO induced fibrosis with NOX2 activation and oxidative stress. NOX2 inhibition successfully attenuated apoptosis, inflammation, and fibrosis with suppression of G2/M arrest. NOX2 inhibition (in vivo) showed improvement in pathological changes with a decrease in oxidative stress without changes in TMAO levels. Thus, TMAO is a key metabolite associated with the AKI-to-CKD transition, and NOX2 activation was identified as a key regulator of TMAO-related AKI-to-CKD transition both in vivo and in vitro.

Atypical post-infectious glomerulonephritis with c-ANCA positivity followed by endocarditis.

Post-infectious glomerulonephritis (PIGN), an uncommon variety of glomerulonephritis (GN), is characterized by emergence of nephritic syndrome within a few weeks following an infectious event. PIGN typically presents as a mild condition and tends to resolve by the time of diagnosis for GN. Aggregatibacter actinomycetemcomitans belongs to the HACEK group of bacteria, which constitutes less than 3% of bacteria responsible for community-acquired infective endocarditis. We present a case of 29-year-old man suspected of lymphoma with B-symptoms along with severe splenomegaly and nephromegaly. Shortly after, he developed an episode of nephritic syndrome accompanied by acute kidney injury (AKI) and high titers of cytoplasmic ANCA (c-ANCA)-positivity. Kidney biopsy revealed PIGN with tubulointerstitial nephritis. Despite treatment with antibiotics and corticosteroid, he visited the emergency room due to worsening dyspnea and multi-organ failure. An echocardiogram showed a bicuspid aortic valve with vegetation unseen on previous echocardiogram. He underwent aortic valve replacement immediately without adverse events. Four months after valve replacement, his renal function and cardiac performance have remained stable. We report a case of PIGN with AKI and high titers of c-ANCA appearing later as an infective endocarditis due to Aggregatibacter actinomycetemcomitans. With careful clinical observation and appropriate and timely management, satisfactory outcomes for patient health are possible.

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Acute kidney injury (AKI) remains a global public health problem with high incidence, high mortality rates, expensive medical costs, and limited treatment options. AKI can further progress to chronic kidney disease (CKD) and eventually end-stage renal disease (ESRD). Previous studies have shown that trauma, adverse drug reactions, surgery, and other factors are closely associated with AKI. With further in-depth exploration, the role of gut microbiota in AKI is gradually revealed. After AKI occurs, there are changes in the composition of gut microbiota, leading to disruption of the intestinal barrier, intestinal immune response, and bacterial translocation. Meanwhile, metabolites of gut microbiota can exacerbate the progression of AKI. Therefore, elucidating the specific mechanisms by which gut microbiota is involved in the occurrence and development of AKI can provide new insights from the perspective of intestinal microbiota for the prevention and treatment of AKI.

Casein Kinase 2 Alpha Inhibition Protects against Sepsis-Induced Acute Kidney Injury.

Sepsis-induced acute kidney injury (AKI) is a common complication in critically ill patients, often resulting in high rates of morbidity and mortality. Previous studies have demonstrated the effectiveness of casein kinase 2 alpha (CK2α) inhibition in ameliorating ischemia-reperfusion-induced AKI. In this study, our aim was to investigate the potential of the selective CK2α inhibitor, 4,5,6,7-tetrabromobenzotriazole (TBBt), in the context of sepsis-induced AKI. To assess this, we initially confirmed an upregulation of CK2α expression following a cecum ligation and puncture (CLP) procedure in mice. Subsequently, TBBt was administered to a group of mice prior to CLP, and their outcomes were compared to those of sham mice. The results revealed that, following CLP, the mice exhibited typical sepsis-associated patterns of AKI, characterized by reduced renal function (evidenced by elevated blood urea nitrogen and creatinine levels), renal damage, and inflammation (indicated by increased tubular injury score, pro-inflammatory cytokine levels, and apoptosis index). However, mice treated with TBBt demonstrated fewer of these changes, and their renal function and architecture remained comparable to that of the sham mice. The anti-inflammatory and anti-apoptotic properties of TBBt are believed to be associated with the inactivation of the mitogen-activated protein kinase (MAPK) and nuclear factor κB (NF-κB) signaling pathways. In conclusion, these findings suggest that inhibiting CK2α could be a promising therapeutic strategy for treating sepsis-induced AKI.

Rapid and persistent decrease in brain tissue oxygenation in ovine gram-negative sepsis.

The changes in brain perfusion and oxygenation in critical illness, which are thought to contribute to brain dysfunction, are unclear due to the lack of methods to measure these variables. We have developed a technique to chronically measure cerebral tissue perfusion and oxygen tension in unanesthetized sheep. Using this technique, we have determined the changes in cerebral perfusion and Po2 during the development of ovine sepsis. In adult Merino ewes, fiber-optic probes were implanted in the brain, renal cortex, and renal medulla to measure tissue perfusion, oxygen tension (Po2), and temperature, and flow probes were implanted on the pulmonary and renal arteries. Conscious sheep were infused with live Escherichia coli for 24 h, which induced hyperdynamic sepsis; mean arterial pressure decreased (from 85.2 ± 5.6 to 71.5 ± 8.7 mmHg), while cardiac output (from 4.12 ± 0.70 to 6.15 ± 1.26 L/min) and total peripheral conductance (from 48.9 ± 8.5 to 86.8 ± 11.5 mL/min/mmHg) increased (n = 8, all P < 0.001) and arterial Po2 decreased (from 104 ± 8 to 83 ± 10 mmHg; P < 0.01). Cerebral perfusion tended to decrease acutely, although this did not reach significance, but there was a significant and sustained decrease in cerebral tissue Po2 (from 32.2 ± 10.1 to 18.8 ± 11.7 mmHg) after 3 h and to 22.8 ± 5.2 mmHg after 24 h of sepsis (P < 0.02). Sepsis induced large reductions in both renal medullary perfusion and Po2 but had no effect in the renal cortex. In ovine sepsis, there is an early decrease in cerebral Po2 that is maintained for 24 h despite minimal changes in cerebral perfusion. Cerebral hypoxia may be one of the factors causing sepsis-induced malaise and lethargy.

Cytomegalovirus in urinary sediment in patients with acute kidney injury.

BACKGROUND: Immunosuppression in solid organ transplantation is associated with frequent infections. Renal allograft recipients are susceptible to opportunistic infections and can acquire human cytomegalovirus (HCMV) infections even within the allograft. There, HCMV can be found in both the glomerulus and tubular cells, but is mostly restricted to specific and circumscribed sites. Therefore, not all organ infections are identifiable by immunohistology for HCMV proteins in fine needle core biopsies. Thus, we performed a urinalysis study to search for HCMV-specific RNA transcripts in the urine sediment of patients with acute kidney injury. METHODS: Urinary sediment of 90 patients with acute kidney injury (AKI), including 48 renal transplant recipients (RTX) and 42 non-transplant recipients (nRTX), was collected from morning urine for RNA extraction and reverse transcription. The copy number of HCMV transcripts was evaluated using a UL132 HCMV-specific probe set and by real-time quantitative polymerase chain reaction (RT-qPCR). RESULTS: Of the 48 RTX patients, ten showed HCMV copies in their urine sediment cells. Within this group, three recipients had negative HCMV serology and received an allograft from an HCMV-seropositive donor. In addition, all three RTX patients on a belatacept-based immunosuppressive regimen had HCMV transcripts in their urine. Of the 42 nRTX patients, only two had detectable HCMV transcripts in urine sediment cells and both were under immunosuppression. CONCLUSIONS: Ten immunosuppressed renal allograft recipients and two immunosuppressed non-transplant patients with AKI showed HCMV copies in urine sediment. Thus, HCMV positivity in urinary sediment appears to be associated with immunosuppression. This study describes a novel noninvasive method for detection of HCMV in urinary sediment. Whether all HCMV infections can be detected or only those with viral replication warrants further investigation.

Candida Administration in Bilateral Nephrectomy Mice Elevates Serum (1→3)-ß-D-glucan That Enhances Systemic Inflammation Through Energy Augmentation in Macrophages.

Systemic inflammation, from gut translocation of organismal molecules, might worsen uremic complications in acute kidney injury (AKI). The monitoring of gut permeability integrity and/or organismal molecules in AKI might be clinically beneficial. Due to the less prominence of Candida albicans in human intestine compared with mouse gut, C. albicans were orally administered in bilateral nephrectomy (BiN) mice. Gut dysbiosis, using microbiome analysis, and gut permeability defect (gut leakage), which was determined by fluorescein isothiocyanate-dextran and intestinal tight-junction immunofluorescent staining, in mice with BiN-Candida was more severe than BiN without Candida. Additionally, profound gut leakage in BiN-Candida also resulted in gut translocation of lipopolysaccharide (LPS) and (1→3)-ß-D-glucan (BG), the organismal components from gut contents, that induced more severe systemic inflammation than BiN without Candida. The co-presentation of LPS and BG in mouse serum enhanced inflammatory responses. As such, LPS with Whole Glucan Particle (WGP, a representative BG) induced more severe macrophage responses than LPS alone as determined by supernatant cytokines and gene expression of downstream signals (NFκB, Malt-1 and Syk). Meanwhile, WGP alone did not induced the responses. In parallel, WGP (with or without LPS), but not LPS alone, accelerated macrophage ATP production (extracellular flux analysis) through the upregulation of genes in mitochondria and glycolysis pathway (using RNA sequencing analysis), without the induction of cell activities. These data indicated a WGP pre-conditioning effect on cell energy augmentation. In conclusion, Candida in BiN mice accelerated gut translocation of BG that augmented cell energy status and enhanced pro-inflammatory macrophage responses. Hence, gut fungi and BG were associated with the enhanced systemic inflammation in acute uremia.

Factors Affecting the Progression of Infection-Related Glomerulonephritis to Chronic Kidney Disease.

Acute glomerulonephritis (AGN) triggered by infection is still one of the major causes of acute kidney injury. During the previous two decades, there has been a major paradigm shift in the epidemiology of AGN. The incidence of poststreptococcal acute glomerulonephritis (PSAGN), which develops after the cure of group A Streptococcus infection in children has decreased, whereas adult AGN cases have been increasing, and those associated with nonstreptococcal infections, particularly infections by Staphylococcus, are now as common as PSAGN. In adult AGN patients, particularly older patients with comorbidities, infections are usually ongoing at the time when glomerulonephritis is diagnosed; thus, the term "infection-related glomerulonephritis (IRGN)" has recently been popularly used instead of "post-infectious AGN". The prognosis of children with PSAGN is generally considered excellent compared with that of adult IRGN cases. However, long-term epidemiological analysis demonstrated that an episode of PSAGN in childhood is a strong risk factor for chronic kidney disease (CKD), even after the complete remission of PSAGN. Although the precise mechanism of the transition from IRGN to CKD remains unknown, its clarification is important as it will lead to the prevention of CKD. In this review, we therefore focus on the possible factors that may contribute to the progression of IRGN into CKD. Four factors, namely, persistent infection, genetic background of the host's complement system, tubulointerstitial changes, and pre-existing histological damage, are discussed.

Identification of Antibiotics That Diminish Disease in a Murine Model of Enterohemorrhagic Escherichia coli Infection.

Infections with enterohemorrhagic Escherichia coli (EHEC) cause disease ranging from mild diarrhea to hemolytic-uremic syndrome (HUS) and are the most common cause of renal failure in children in high-income countries. The severity of the disease derives from the release of Shiga toxins (Stx). The use of antibiotics to treat EHEC infections is generally avoided, as it can result in increased stx expression. Here, we systematically tested different classes of antibiotics and found that their influence on stx expression and release varies significantly. We assessed a selection of these antibiotics in vivo using the Citrobacter rodentium ϕstx2dact mouse model and show that stx2d-inducing antibiotics resulted in weight loss and kidney damage despite clearance of the infection. However, several non-Stx-inducing antibiotics cleared bacterial infection without causing Stx-mediated pathology. Our results suggest that these antibiotics might be useful in the treatment of EHEC-infected human patients and decrease the risk of HUS development.

Antimicrobial therapy with aminoglycoside or meropenem in the intensive care unit for hospital associated infections and risk factors for acute kidney injury.

There have historically been concerns of acute kidney injury (AKI) with the use of aminoglycosides. The present study aimed to compare the AKI incidence and mortality rate between critically ill patients treated with aminoglycoside or meropenem in the intensive care unit setting using a propensity score matching approach. This cross-sectional study was conducted at two university hospitals from January 2011 to October 2017. Clinical and laboratorial data were evaluated to exclude potential confounders and to calculate the Charlson index. AKI was classified according to the Acute Kidney Injury Network criteria. All tests were two-tailed, and a p value ≤ 0.05 was considered significant in the univariate and multivariate analyses. We included 494 patients, 95 and 399 of whom used meropenem and aminoglycoside, respectively. Patients in the subgroup that used meropenem were matched with controls (aminoglycoside). Among the 494 patients, 120 developed any grade of AKI (24.2%). After propensity score matching, there were no significant differences in AKI incidence and mortality rate between the aminoglycoside and meropenem groups (p = 0.324 and 0.464, respectively). Patients on the aminoglycoside regimen neither presented a higher AKI incidence nor mortality rate when compared with those on the meropenem regimen. Aminoglycosides may be a safe option for the treatment of critically ill patients on carbapenem sparing antimicrobial stewardship programs.

The wrong Spirochaete? Acute kidney injury in a returning traveller with syphilis - a case report.

BACKGROUND: Syphilis has seen an increased incidence in recent years and can have serious and irreversible consequences if left un-diagnosed and untreated. This case report describes a presentation of syphilis and acute kidney injury - a scenario sparsely described in existing literature. CASE PRESENTATION: This 43-year old Man who has Sex with Men (MSM) presented to the emergency department with a 3-week history of vomiting and headaches, progressing to include pyrexia. These symptoms started following his return from a 2-week cruise in Central America throughout which he had been well. He had a background of well-controlled human immunodeficiency virus (HIV). On admission he had an Acute Kidney Injury (AKI) stage 3, without hydronephrosis, presumed to be pre-renal. Leptospirosis, the main differential, was negative serologically. 'Pyrexia of unknown origin' testing was performed, and cefuroxime commenced. Later in the admission, syphilis testing indicated an acute infection and he completed a full treatment course of benzylpenicillin. This, alongside intravenous fluids, resulted in symptom and renal resolution in 9 days and restoration of renal function. CONCLUSIONS: Renal complications in syphilis are rare, furthermore the majority of those documented occur in latent syphilis and are irreversible. There are limited numbers of other documented cases of AKI in acute syphilis, which like the gentleman in this case were reversible and did not lead to permanent kidney damage. This case adds to the knowledge base of AKI in initial presentation of syphilis. It also demonstrates not only the importance of taking a sexual history in patients with new infective symptoms but that testing for syphilis in at-risk groups regardless of history should be performed given its rising incidence. These considerations by physicians can lead to prompt diagnosis and management of syphilis and improve patient care and long-term outcomes.

Right-sided infective endocarditis in association with a left-to-right shunt complicated by haemoptysis and acute renal failure: a case report.

BACKGROUND: Infective endocarditis has a relevant clinical impact due to its high morbidity and mortality rates. Right-sided endocarditis has lower complication rates than left-sided endocarditis. Common complications are multiple septic pulmonary embolisms, haemoptysis, and acute renal failure. Risk factors associated with right-sided infective endocarditis are commonly related to intravenous drug abuse, central venous catheters, or infections due to implantable cardiac devices. However, patients with congenital ventricular septal defects might be at high risk of endocarditis and haemodynamic complications. CASE PRESENTATION: In the following, we present the case of a 23-year-old man without a previous intravenous drug history with tricuspid valve Staphylococcus aureus endocarditis complicated by acute renal failure and haemoptysis caused by multiple pulmonary emboli. In most cases, right-sided endocarditis is associated with several common risk factors, such as intravenous drug abuse, a central venous catheter, or infections due to implantable cardiac devices. In this case, we found a small perimembranous ventricular septal defect corresponding to a type 2 Gerbode defect. This finding raised the suspicion of a congenital ventricular septal defect complicated by a postendocarditis aneurysmal transformation. CONCLUSIONS: Management of the complications of right-sided infective endocarditis requires a multidisciplinary approach. Echocardiographic approaches should include screening for ventricular septal defects in patients without common risk factors for tricuspid valve endocarditis. Patients with undiagnosed congenital ventricular septal defects are at high risk of infective endocarditis. Therefore, endocarditis prophylaxis after dental procedures and/or soft-tissue infections is highly recommended. An acquired ventricular septal defect is a very rare complication of infective endocarditis. Surgical management of small ventricular septal defects without haemodynamic significance is still controversial.

High-Density Lipoprotein, Mean Platelet Volume, and Uric Acid as Biomarkers for Outcomes in Patients With Sepsis: An Observational Study.

BACKGROUND: We conducted an observational study evaluating the association between uric acid, mean platelet volume (MPV), and high-density lipoprotein (HDL) with complications and outcomes of patients with sepsis in a critical care setting. METHODS: We followed patients with a diagnosis of severe sepsis and septic shock for a maximum of 28 days. Main outcomes assessed included length of stay (LOS), the need for renal replacement therapy (RRT), assisted mechanical ventilation (AMV), and vasopressor support as well as in-unit mortality. RESULTS: The overall average age of the 37 patients enrolled was 48.1 (19.8) years; among them, 37.8% were male. Abdominal related (43.2%) and pulmonary (29.7%) were the main sites of infection. The overall Acute Physiology and Chronic Health Evaluation 2 (APACHE-2) median score was 19 (9-24). Acute kidney injury (AKI) was observed in 46.9% of the sample. In all, 54.1% required vasopressor support, 54.1% AMV, and 35.1% RRT. Patients with bacteremia were significantly more likely to require vasopressor support and those with urinary tract infections were significantly younger. We found increasing ΔMPV levels, higher APACHE-2 scores, lower HDL values, and a reduced age to be associated with a longer LOS. Higher scores on the APACHE-2 scale and lower levels of HDL significantly associated with higher odds for developing AKI. The need for vasopressor support was significantly associated with higher values of 72-hour MPV and with higher levels of baseline uric acid and lower values of initial HCO3. Initial and 72-hour levels of MPV and higher scores in the APACHE-2 were all significantly correlated with the need for AMV. An increased probability of dying during follow-up was significantly correlated with increasing age. CONCLUSION: We were able to establish significant associations between our candidate biomarkers and relevant outcomes for patients with sepsis. Our results support the use of these low-cost biomarkers in the assessment of prognosis of patients with sepsis.

Characteristics and Outcomes of Patients With and Without Type 2 Diabetes Mellitus and Pulmonary Sepsis.

PURPOSE: To date, studies have provided conflicting results regarding the impact of type 2 diabetes mellitus (DM) on sepsis-related outcomes. Our objective is to understand the impact of type 2 DM in bacterial pneumonia and sepsis-related intensive care unit (ICU) outcomes. METHODS: Retrospective study using Multiparameter Intelligent Monitoring in Intensive Care III database. We included 1698 unique patients admitted with sepsis secondary to bacterial pneumonia to the ICU within the time period of 2001 to 2012. RESULTS: The type 2 DM group had an increased incidence of acute kidney injury (67.9% vs 58.1%, P < .01) and need for dialysis compared to the non-DM group. There was no difference in mortality, microbiology, other organ failure, or hospital length of stay between the type 2 DM and non-DM group. Lower admission blood glucose was associated with increased mortality in patients with type 2 DM (49% at ≤120 mg/dL, 35.1% at 121-180 mg/dL, and 32.1% at >180 mg/dL) but not in non-DM patients. Conversely, higher mean glucose during the hospital stay was associated with increased mortality in non-DM patients (24.7% at ≤120 mg/dL, 45.1% at 121-180 mg/dL, and 73.0% at >180 mg/dL) but not in patients with type 2 DM. CONCLUSIONS: Our findings demonstrated that type 2 DM does not increase the overall mortality. Our findings of increased mortality in both type 2 DM patients with lower admission glucose, and non-DM patients with higher mean glucose during the hospital stay needs to be further evaluated. Future studies in regards to this could lead to personalized glucose treatment goals for patients.

Clinical and subclinical acute kidney injury in multidrug-resistant septic patients treated with colistimethate sodium: Incidence and clinical outcomes.

AIM: Colistimethate sodium (CMS) has been postulated as the principal cause of high incidence of clinical acute kidney injury (AKI) in multidrug-resistance (MDR) septic patients with normal baseline serum creatinine (sCr) who were treated with CMS. This prospective observational study was conducted to examine the incidence and clinical outcomes of clinical and subclinical AKI in MDR septic patients receiving CMS. METHODS: Forty-two MDR septic patients with normal sCr who required CMS were included. Clinical AKI was diagnosed by increased sCr levels according to the KDIGO2012 criteria while subclinical AKI was identified by elevated levels of urinary neutrophil gelatinase-associated lipocalin (uNGAL > 150 ng/mL) or urinary liver-type fatty-acid-binding protein (uL-FABP > 10.5 ng/mL). RESULTS: Clinical AKI was noted in 47.6% of patients on day 5 and 38.1% on day 7 after initiating CMS. By using uL-FABP, subclinical AKI was observed in 45.2% and 54.8% on day 5 and 7, respectively. At baseline prior to CMS treatment, subclinical AKI was already present in 90%. The baseline uL-FABP was superior to the baseline uNGAL in early prediction of clinical AKI on day 5. The subclinical AKI patients had comparable worse outcomes as clinical AKI patients. CONCLUSION: The incidence of subclinical AKI in MDR septic patients before CMS treatment was extremely high. The baseline uL-FABP provided the best predictive capacity of clinical AKI. The causes of clinical AKI might include the persistence of sepsis process, subclinical AKI and CMS nephrotoxicity. Proper management of subclinical AKI patients before CMS initiation should be concerned to prevent further renal damage and improve patient and renal outcomes.

Incidence of acute kidney injury and use of renal replacement therapy in intensive care unit patients in Indonesia.

BACKGROUND: Currently, there is limited epidemiology data on acute kidney injury (AKI) in Indonesia. Therefore, we assessed the incidence of AKI and the utilization of renal replacement therapy (RRT) in Indonesia. METHODS: Demographic and clinical data were collected from 952 ICU participants. The participants were categorized into AKI and non-AKI groups. The participants were further classified according to the 3 different stages of AKI as per the Kidney Disease Improving Global Outcome (KDIGO) criteria. RESULTS: Overall incidence of AKI was 43%. The participants were divided into three groups based on the AKI stages: 18.5% had stage 1, 33% had stage 2, and 48.5% had stage 3. Primary diagnosis of renal disease and high APACHE II score were the risk factors associated with AKI (OR = 4.53, 95% CI: 1.67-12.33, p = 0.003 and OR = 1.14 per 1 unit increase, 95% CI: 1.09-1.20, p < 0.001, respectively). Chronic kidney disease was the risk factor for severe AKI. Sepsis was the leading cause of AKI. Among the AKI participants, 24.6% required RRT. The most common RRT modalities were intermittent hemodialysis (71.7%), followed by slow low-efficiency dialysis (22.8%), continuous renal replacement therapy (4.3%), and peritoneal dialysis (1.1%). CONCLUSIONS: This study showed that AKI was a common problem in the Indonesian ICU. We strongly believe that identification of the risk factors associated with AKI will help us develop a predictive score for AKI so we can prevent and improve AKI outcome in the future.

The urinary microbiome shows different bacterial genera in renal transplant recipients and non-transplant patients at time of acute kidney injury - a pilot study.

BACKGROUND: In the past urine was considered sterile. Through the introduction of next generation sequencing, it has become clear that a urinary microbiome exists. Acute kidney injury (AKI) represents a major threat to kidney transplant recipients. Remarkable changes in the urinary metabolome occur during AKI, which may influence the urinary microbiome. To our knowledge, this is the first study that examines the urinary microbiome in renal transplant recipients (RTX) and non-transplant recipients (nRTX) at time of AKI. METHODS: In this cross-sectional pilot-study the urinary microbiome of 21 RTX and 9 nRTX with AKI was examined. Clean catch morning urine samples were obtained from all patients on the first day of AKI diagnosis. AKI was defined according to KDIGO guidelines. Urinary microbiota and the urinary metabolome during AKI were assessed in one patient. 16S rRNA sequencing was performed. Sequences were processed using UPARSE-pipeline for operational taxonomic units (OTU) and taxon finding. RESULTS: We successfully extracted and sequenced bacterial DNA from 100% of the urine samples. All 30 patients revealed at least 106,138 reads. 319 OTU and 211 different genera were identified. The microbiotic diversity richness in the RTX group was no different from the nRTX group. Eighteen genera were solely present in nRTX and 7 in RTX. CONCLUSIONS: The urinary microbiome at time of AKI showed different bacterial genera in RTX compared to nRTX. The nRTX group exhibited no different diversity to the RTX group. Irrespective of the status of a previous renal transplantation, the urinary microbiome comprised > 210 different genera. An intraindividual change in microbiota diversity and richness was observed in one study patient during recovery from AKI.

Human umbilical cord mesenchymal stem cell exosomes alleviate sepsis-associated acute kidney injury via regulating microRNA-146b expression.

Human umbilical cord mesenchymal stem cell-derived exosomes (HucMSC-Ex) are a promising tool for the repair of acute kidney injury (AKI) caused by cisplatin and ischemia/reperfusion. However, the roles of hucMSC-Ex in sepsis-associated AKI repair and its mechanism are largely unknown. Hence, we constructed a sepsis model through cecal ligation and puncture (CLP), testing the benefits of hucMSC-Ex in the sepsis in terms of survival rate, serum renal markers levels, morphological changes and apoptosis. Immunohistochemistry staining and immunofluorescence assay were used to investigate the role of NF-κB activity in the repair of sepsis-associated AKI with hucMSC-Ex. HK-2 cells were transfected with microRNA-146b (miR-146b) mimics and inhibitors, respectively, and the regulatory effect of miR-146b on NF-κB activity was studied. We found that hucMSC-Ex treatment significantly decreased the serum creatinine (Cr) and blood urea nitrogen (BUN) levels, ameliorated the morphological damage and inhibited renal tubular cells apoptosis. More importantly, the survival rate at 72 h was 28% in CLP group and 45% in hucMSC-Ex group, respectively. Treatment with hucMSC-Ex improved survival in mice with sepsis. These effects of hucMSC-Ex were mediated by the inhibition of NF-κB activity and the lessening of pro-inflammatory response. Furthermore, hucMSC-Ex significantly increased miR-146b expression in kidney tissues. Conversely, interleukin (IL)-1 receptor-associated kinase (IRAK1) level, which is the target gene of miR-146b, clearly decreased in hucMSC-Ex group. In brief, this study showed that treatment with hucMSC-Ex decreased IRAK1 expression through the up-regulation of miR-146b level, led to the inhibition of NF-κB activity, and eventually alleviated sepsis-associated AKI and improved survival in mice with sepsis. HucMSC-Ex may be a novel therapeutic agent for the reduction of sepsis-associated AKI.

Vancomycin Area Under the Curve and Acute Kidney Injury: A Meta-analysis.

BACKGROUND: This study analyzed the relationship between vancomycin area under the concentration-time curve (AUC) and acute kidney injury (AKI) reported across recent studies. METHODS: A systematic review of PubMed, Medline, Scopus, and compiled references was conducted. We included randomized cohort and case-control studies that reported vancomycin AUCs and risk of AKI (from 1990 to 2018). The primary outcome was AKI, defined as an increase in serum creatinine of ≥0.5 mg/L or a 50% increase from baseline on ≥2 consecutive measurements. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. Primary analyses compared the impact of AUC cutpoint (greater than ~650 mg × hour/L) and AKI. Additional analysis compared AUC vs trough-guided monitoring on AKI incidence. RESULTS: Eight observational studies met inclusion/exclusion criteria with data for 2491 patients. Five studies reported first-24-hour AUCs (AUC0-24) and AKI, 2 studies reported 24- to 48-hour AUCs (AUC24-48) and AKI, and 2 studies reported AKI associated with AUC- vs trough-guided monitoring. AUC less than approximately 650 mg × hour/L was associated with decreased AKI for AUC0-24 (OR, 0.36 [95% CI, .23-.56]) as well as AUC24-48 (OR, 0.45 [95% CI, .27-.75]). AKI associated with the AUC monitoring strategy was significantly lower than trough-guided monitoring (OR, 0.68 [95% CI, .46-.99]). CONCLUSIONS: AUCs measured in the first or second 24 hours and lower than approximately 650 mg × hour/L may result in a decreased risk of AKI. Vancomycin AUC monitoring strategy may result in less vancomycin-associated AKI. Additional investigations are warranted.

Regulation of Fn14 stability by SCFFbxw7α during septic acute kidney injury.

Acute kidney injury (AKI) initiated by sepsis remains a thorny problem despite recent advancements in its clinical management. Having been found to be activated during AKI, fibroblast growth factor-inducible molecule 14 (Fn14) may be a potential therapeutic target because of its involvement in the molecular basis of injury. Here, we report that LPS induces apoptosis of mouse cortical tubule cells mediated by Fn14, for which simultaneous Toll-like receptor (TLR)4 activation is required. Mechanistically, TLR4 activation by lipopolysaccharide, through disassociating E3 ligase SCFFbxw7α from Fn14, dismantles Lys48-linked polyubiquitination of Fn14 and stabilizes it. Pharmacological deactivation of Fn14 with monoclonal antibody ITEM-2 provides effective protection against lethal sepsis and AKI in mice. Our study underscores an adaptive mechanism whereby TLR4 regulates SCFFbxw7α-dependent Fn14 stabilization during inflammatory tubular damage and further supports investigation of targeting Fn14 in clinical trials of patients with septic AKI.