Project description:Interstitial renal inflammation contributes to the transition from acute kidney injury (AKI) to chronic kidney disease (CKD). Recently, protein lactylation modification has emerged as a novel mechanism mediating chronic organ damage. We investigated lactylated protein profiles and the role of protein lactylation during AKI progression. Severe and moderate AKI mouse models were constructed by bilateral renal ischemia for 35 and 25 min respectively. The lactylation enhancer and inhibitors were used to verify the effect of protein lactylation. Lactylated proteomics was used to detect lactylated protein changes in kidneys, and the lactylated proteins related to kidney injury were screened for verification. We observed significantly higher lactate and protein lactylation levels in the severe than in the moderate AKI model 1–28 days post-injury. Inhibition of protein lactylation protected against renal interstitial fibrosis. In vitro and in vivo experiments demonstrated that protein lactylation activated Nod-like receptor protein 3 (NLRP3) inflammasomes, promoting the AKI–CKD transition. Comprehensive lactylome profiling of severe AKI models revealed a role for lactylated proteins in metabolic pathways, primarily the tricarboxylic acid (TCA) cycle where the rate-limiting enzyme, citrate synthase (CS), exhibited significantly elevated lactylation levels 3–7 days post-AKI induction; K370 was the most significant lysine residue. In vitro, following hypoxia/reoxygenation, the modified/lactylated K370T group significantly decreased CS activity and mitochondrial function. Furthermore, CS-K370 lactylation activated the NLRP3 inflammasome. Lactylation of CS promotes the AKI–CKD transition through NLRP3 inflammasome activation. Inhibition of CS lactylation shows therapeutic potential for preventing this transition.
Project description:Diabetic patients have increased susceptibility to acute kidney injury (AKI), and AKI could progress to chronic tubulointerstitial injury and fibrosis, referred to as AKI-to-chronic kidney disease (AKI-to-CKD) transition. However, whether diabetes directly promotes AKI-to-CKD transition is not known. We previously showed that reticulon-1A (RTN1A), a gene highly upregulated in injured renal tubular epithelial cells (RTECs), promotes AKI-to-CKD transition in nondiabetic settings. Therefore, we also examined whether reducing RTN1A expression could attenuate diabetes-induced AKI-to-CKD transition. Diabetes was induced by a high-fat diet and streptozotocin injections, and unilateral ischemic reperfusion injury was created as an AKI model in control, diabetic, and RTEC-specific Rtn1a-knockdown diabetic mice. AKI induced greater renal function decline, tubulointerstitial injury, and fibrosis in diabetic mice than in nondiabetic mice. Reduction of RTN1A markedly reduced the CKD development following AKI in diabetic mice, which was associated with reduced ER stress and mitochondrial dysfunction in RTECs. These findings indicate that diabetes markedly accelerates AKI-to-CKD transition and that RTN1A is a crucial mediator of diabetes-induced AKI-to-CKD transition. The development of RTN1A inhibitors could potentially attenuate AKI-to-CKD transition in diabetic patients.
Project description:BackgroundAcute kidney injury (AKI) is associated with short- and long-term complications but the consequences of the AKI-to-CKD transition are still poorly understood. We aimed to evaluate the association between the AKI-to-CKD transition and the long-term risk of infection.MethodsThis retrospective study included patients admitted in a tertiary hospital with community-acquired AKI in 2013 and 2014 who had their estimated glomerular filtration rate (eGFR) assessed at 3 months (±2 weeks) after serum creatinine peaked in the AKI episode. Key exclusion criteria were baseline CKD or confounding factors (active neoplasia, primary immunodeficiency, human immunodeficiency virus, immunosuppressive drugs). The association between the AKI-to-CKD transition (defined as an eGFR <60 ml/min/1.73 m2 at 3 months) and long-term infections (defined using clinical features, blood/urine analysis, cultures and imaging) was assessed during a follow-up of 9 months (range 2-56).ResultsAmong the 1731 patients admitted with AKI, 367 (21%) were included in the present analysis (64% male, 71 ± 15 years). Three months after AKI, 159 (43%) developed AKI-to-CKD transition. Baseline and post-AKI eGFR were independent predictors of AKI-to-CKD transition [hazard ratio (HR) 0.97, P = .044 and HR 0.96, P < .001, respectively].During follow-up, 153 (42%) patients developed an infection. Factors associated with infection were older age, cognitive impairment, lower post-AKI eGFR, eGFR loss from baseline to 3 months and AKI-to-CKD transition. Adjusted Cox regression showed that baseline eGFR, 3-month eGFR, eGFR loss and AKI-to-CKD transition were independent predictors of the long-term risk of infection.ConclusionsThe AKI-to-CKD transition independently predicts the long-term risk of infection following an episode of AKI.
Project description:BackgroundRecent research shows AKI increases the risk of incident CKD. We hypothesized that perioperative AKI may confer increased risk of subsequent CKD compared to nonperioperative AKI.MethodsA MEDLINE search was performed for "AKI, CKD, chronic renal insufficiency, surgery, and perioperative" and related terms yielded 5209 articles. One thousand sixty-five relevant studies were reviewed. One thousand six were excluded because they were review, animal, or pediatric studies. Fifty-nine studies underwent full manuscript review by two independent evaluators. Seventeen met all inclusion criteria and underwent analysis. Two-by-two tables were constructed from AKI +/- and CKD +/- data. The R package metafor was employed to determine odds ratio (OR), and a random-effects model was used to calculate weighted ORs. Leave-1-out, funnel analysis, and structured analysis were used to estimate effects of study heterogeneity and bias.ResultsNonperioperative studies included studies of oncology, percutaneous coronary intervention, and myocardial infarction patients. Perioperative studies comprised patients from cardiac surgery, vascular surgery, and burns. There was significant heterogeneity, but risk of bias was overall assessed as low. The OR for AKI versus non-AKI patients developing CKD in all studies was 4.31 (95% CI 3.01-6.17; p < 0.01). Nonperioperative subjects demonstrated OR 3.32 for developing CKD compared to non-AKI patients (95% CI 2.06-5.34; p < 0.01) while perioperative patients demonstrated OR 5.20 (95% CI 3.12-8.66; p < 0.01) for the same event.ConclusionsWe conclude that studies conducted in perioperative and nonperioperative patient populations suggest similar risk of development of CKD after AKI.
Project description:Inflammation has recently been attributed to dysbiosis of the gut microbiome, which has been linked to proteinuria in chronic kidney disease. Since Adriamycin® (ADR) is widely used to induce proteinuria in mouse models, the aim of this study was to explore the potential effect of gut microbiome on this process. Both ADR resistant (C57BL/6) and susceptible (BALB/C) strains were part of the induced nephropathy with ADR injection. BALB/C mice significantly presented increased urinary albumin/creatinine ratio (UACR) with renal lesions in pathology, but C57BL/6 mice were absent from kidney damage. Species and genus level resolution analysis showed a shift in gut microbial profile between BALB/C and C57BL/6 mice. ADR further altered the stool microbiome in BALB/C mice, particularly with enrichment of Odoribacter and depletion of Turicibacter, Marvinbryantia and Rikenella. Moreover, the level of UACR in BALB/C mice was marked related to the abundance of Marvinbryantia, Odoribacter and Turicibacter in stool. Meanwhile, ADR remarkably increased the serum levels of interleukin (IL)-2 in BALB/C mice, but not in C57BL/6 mice. It is suggested that the favorably altered stools as shown in the microbiome might promote the inflammation and proteinuria in ADR-sensitive mice, which provides a new insight on the pathogenicity of chronic kidney disease.
Project description:Acute kidney injury (AKI) with maladaptive repair induces transition to chronic kidney disease (CKD) through inflammation, oxidative stress, and inappropriate homeostatic responses, including senescence and apoptosis. Here, we demonstrate that administration of cyclo Histidine-Proline (Cyclo His-Pro, CHP) protects against kidney injury and progression to CKD. Exogenous CHP pre-treatment preserved kidney function and produced significant reduction in tubular injury, apoptosis, and inflammatory cell infiltration in an ischemia-reperfusion injury (IRI) model. Compared with 5/6 nephrectomy (Nx) control rats, kidney function was protected and fibrosis was attenuated in CHP-treated 5/6 Nx rats. CHP also improved kidney injury in a unilateral ureteral obstruction (UUO) model with both prophylactic and therapeutic treatment regimens. To translate our observations to the human setting, we evaluated the relationship between endogenous CHP levels and CKD progression. As kidney function deteriorated, plasma CHP concentration increased, whereas tissue expression of Nrf2 displayed a negative relationship with CKD progression, suggesting that plasma CHP levels increase as a compensatory process to enhance the Nrf2 pathway activity. The data presented here support the efficacy of exogenous CHP treatment in preventing AKI-to-CKD transition potentially through Nrf2 pathway activation. Results: Cyclo (His-Pro) is an effective treatment for the AKI-to-CKD Transition
Project description:Whole bone strength and resistance to fracture are determined by a combination of bone quantity and bone quality - key factors in determining risk for osteoporosis and age-related fractures. Recent preclinical studies have shown that alterations to the gut microbiome can influence bone quantity as well as bone tissue quality. Prior work on the gut microbiome and bone has been limited to young animals, and it is unknown if the gut microbiome can alter bone tissue strength in aged animals. Here we ask if alterations to the constituents of the gut microbiome influence bone strength in older mice (12-24 months of age). Male C57BL/6J mice raised on a standard chow diet until 12 months of age were assigned to one of three diets: high glycemic, low glycemic, or low glycemic diet containing antibiotics (ampicillin and neomycin) to modify the constituents of the gut microbiome. The group fed the low glycemic diet containing antibiotics showed reductions in whole bone strength that could not be explained by geometry, indicating reduced bone tissue strength (p < 0.007). The high glycemic diet group had larger bone cross-sectional area and moment of inertia and a corresponding greater bone strength as compared to the low glycemic groups, however tissue strength did not noticeably differ from that of the low glycemic group. These findings demonstrate that modifying the gut microbiome in aged mice can alter bone tissue quality.
Project description:BackgroundInflammation is a key driver of the transition of acute kidney injury to progressive fibrosis and chronic kidney disease (AKI-to-CKD transition). Blocking a-disintegrin-and-metalloprotease-17 (ADAM17)-dependent ectodomain shedding, in particular of epidermal growth factor receptor (EGFR) ligands and of the type 1 inflammatory cytokine tumor necrosis factor (TNF), reduces pro-inflammatory and pro-fibrotic responses after ischemic AKI or unilateral ureteral obstruction (UUO), a classical fibrosis model. Metalloprotease or EGFR inhibition show significant undesirable side effects in humans. In retrospective studies anti-TNF biologics reduce the incidence and progression of CKD in humans. Whether TNF has a role in AKI-to-CKD transition and how TNF inhibition compares to EGFR inhibition is largely unknown.MethodsMice were subjected to bilateral renal ischemia-reperfusion injury or unilateral ureteral obstruction. Kidneys were analyzed by histology, immunohistochemistry, qPCR, western blot, mass cytometry, scRNA sequencing, and cytokine profiling.ResultsHere we show that TNF or EGFR inhibition reduce AKI-to-CKD transition and fibrosis equally by about 25%, while combination has no additional effect. EGFR inhibition reduced kidney TNF expression by about 50% largely by reducing accumulation of TNF expressing immune cells in the kidney early after AKI, while TNF inhibition did not affect EGFR activation or immune cell accumulation. Using scRNAseq data we show that TNF is predominantly expressed by immune cells in AKI but not in proximal tubule cells (PTC), and PTC-TNF knockout did not affect AKI-to-CKD transition in UUO. Thus, the anti-inflammatory and anti-fibrotic effects of the anti-TNF biologic etanercept in AKI-to-CKD transition rely on blocking TNF that is released from immune cells recruited or accumulating in response to PTC-EGFR signals.ConclusionShort-term anti-TNF biologics during or after AKI could be helpful in the prevention of AKI-to-CKD transition.
Project description:Clodronate liposomes are bisphosphonates encapsulated by liposomes that are known to induce macrophage depletion in vivo. In a previous study, clodronate liposomes improved renal ischemia/reperfusion (I/R) injury in mice, which may be due to effects on macrophage phenotypes. However, how inflammatory cytokines secretion participates is unknown. In this study, we investigated the effect of macrophages in the I/R kidney by depleting macrophages with clodronate liposomes and changing inflammatory cytokines. C57BL/6 mice underwent I/R injury with or without clodronate liposomes administration on Days 5 and 15. Tubular injury, collagen deposition, and fibrosis were detected and analyzed by histological staining, immunocytochemistry (IHC), flow cytometry (FACS), and reverse transcription-polymerase chain reaction (RT-PCR). Inflammatory cytokines were detected and analyzed by Western blotting and RT-PCR. We found that clodronate liposomes alleviated renal fibrosis and tissue damage on both Days 5 and 15. KIM-1, IL-10, and TGF-β were reduced significantly in the clodronate liposomes treatment group. However, TNF-α was not different between the clodronate liposomes treatment group and the phosphate-buffered saline treatment group on either Day 5 or Day 15. Thus, clodronate liposomes can alleviate renal fibrosis and tissue damage and reduce the inflammatory cytokines IL-10 and TGF-β, suggesting that clodronate liposomes alleviate renal fibrosis may because of M1/M2 polarization.
Project description:IntroductionDisruption of gut microbiota underpins some of the metabolic alterations observed in chronic kidney disease (CKD).MethodsIn a nonrandomized, open-label, 3-phase pilot trial, with repeated measures within each phase, we examined the efficacy of oligofructose-enriched inulin (p-inulin) in changing the gut microbiome and their metabolic products in 15 patients with CKD. The stability of microbiome and metabolome was studied during the pretreatment phase (8 weeks), a p-inulin treatment phase (12 weeks), and a post treatment phase (8 weeks) of the study.ResultsStudy participants completed 373 of the 420 expected study visits (88.8%). Adherence to p-inulin was 83.4%. 16S rRNA sequencing was performed in 368 stool samples. A total of 1085 stool, urine, and plasma samples were subjected to untargeted metabolomic studies. p-inulin administration altered the composition of the gut microbiota significantly, with an increase in abundance of Bifidobacterium and Anaerostipes. Intersubject variations in microbiome and metabolome were larger than intrasubject variation, indicating the stability of the gut microbiome within each phase of the study. Overall metabolite compositions assessed by beta diversity in urine and stool metabolic profiles were significantly different across study phases. Several specific metabolites in stool, urine, and plasma were significant at false discovery rate (FDR) ≤ 0.1 over phase. Specifically, there was significant enrichment in microbial metabolites derived from saccharolysis.ConclusionResults from our study highlight the stability of the gut microbiome and the expansive effect of p-inulin on microbiome and host cometabolism in patients with CKD. Findings from this study will enable rigorous design of microbiome-based intervention trials.