Fibrosis of the kidney is caused by the prolonged injury and deregulation of normal wound healing and repair processes, and by an excess deposition of extracellular matrices. Despite intensive research, our current understanding of the precise mechanism of fibrosis is limited. There is a connection between fibrotic events involving inflammatory and noninflammatory glomerulonephritis, inflammatory cell infiltration, and podocyte loss. The current review will discuss the inflammatory response after renal injury that leads to fibrosis in relation to non-inflammatory mechanisms.

The human kidneys filter 180 l of blood every day via about 2.5 million glomeruli. The three layers of the glomerular filtration apparatus consist of fenestrated endothelium, specialized extracellular matrix known as the glomerular basement membrane (GBM) and the podocyte foot processes with their modified adherens junctions known as the slit diaphragm (SD). In this study we explored the contribution of podocyte beta1 integrin signaling for normal glomerular function. Mice with podocyte specific deletion of integrin beta1 (podocin-Cre beta1-fl/fl mice) are born normal but cannot complete postnatal renal development. They exhibit detectable proteinuria on day 1 and die within a week. The kidneys of podocin-Cre beta1-fl/fl mice exhibit normal glomerular endothelium but show severe GBM defects with multilaminations and splitting including podocyte foot process effacement. The integrin linked kinase (ILK) is a downstream mediator of integrin beta1 activity in epithelial cells. To further explore whether integrin beta1-mediated signaling facilitates proper glomerular filtration, we generated mice deficient of ILK in the podocytes (podocin-Cre ILK-fl/fl mice). These mice develop normally but exhibit postnatal proteinuria at birth and die within 15 weeks of age due to renal failure. Collectively, our studies demonstrate that podocyte beta1 integrin and ILK signaling is critical for postnatal development and function of the glomerular filtration apparatus.

Background/Aims: The aim of this study was to examine the recent clinical trends and antibiotic susceptibilities of the causative microorganisms in renal and perirenal abscesses, and to elucidate the factors associated with treatment strategies.Methods: We retrospectively analyzed 56 patients who were diagnosed with renal and perirenal abscesses at our hospital from January 2000 to September 2007.Results: The mean age of the patients was 53.5 years, and a female predominance of patients (75%) was observed. Diabetes mellitus (44.6%) was the most common predisposing condition. The mean duration of symptoms before diagnosis was 11.6 days, and fever (75%) was the most common symptom. Escherichia coli (44%) and Klebsiella pneumoniae (28%) were common pathogens, and the rates of susceptibility of E. coli isolates to ampicillin, cephalothin, cefotaxime, trimethoprim-sulfamethoxazole, ciprofloxacin, gentamicin, and imipenem were 18.2%, 27.3%, 72.7%, 72.7%, 63.6%, 63.6%, and 100%, respectively. Abscesses were classified according to the location as follows: renal abscess (n=31, 55.4%) and perirenal abscess±renal abscess (n=25, 44.6%). In the renal abscess group, the infection rate of gram-negative organisms was higher than in the perirenal abscess group. Patients were also divided according to the treatment modality: antibiotics only (n=20, 35.7%) and percutaneous intervention or surgery (n=36, 64.3%). Patients who had a perirenal abscess or a large renal abscess required more invasive treatment.Conclusions: This study revealed somewhat different results from those of previous studies. Clinical and microbial differences were observed between the renal and perirenal abscess groups. Abscess location and the size of the renal abscess were the factors associated with treatment strategies.

Hyperuricemia is a common finding in chronic kidney disease due to decreased uric acid clearance. The role of uric acid as a risk factor for chronic kidney disease has been largely debated, and recent studies suggested a role of uric acid in the causation and progression of kidney fibrosis, a final common pathway in chronic kidney disease. Uric acid and xanthine oxidase may contribute to kidney fibrosis mainly by inducing inflammation, endothelial dysfunction, oxidative stress, and activation of the renin-angiotensin system. Besides, hyperuricemia induces alterations in renal hemodynamics via afferent arteriolopathy and contributes to the onset and progression of kidney fibrosis. Xanthine oxidase inhibitors may prevent kidney damage via lowering uric acid and/or inhibiting xanthine oxidase. However, there is still no sufficient evidence from interventional clinical researches supporting the causal relationship between uric acid and kidney fibrosis. The effect and role of xanthine oxidase inhibitors in preventing kidney fibrosis and chronic kidney disease progression must be further explored by performing future large scale clinical trials.

Extracellular volume expansion, measured by MFBIA, does not help preserve residual renal function, and is harmful for the technical and patient survival in Korean peritoneal dialysis patients.

BackgroundFluid overload is known to be associated with increased mortality in patients with acute kidney injury (AKI) who are critically ill. In this study, we intended to uncover whether the adverse effect of fluid overload on survival could be applied to all of the patients with AKI who received continuous renal replacement therapy (CRRT).MethodsWe analyzed 341 patients with AKI who received CRRT in our intensive care units. The presence of fluid overload was defined as a minimum 10% increase in body weight from the baseline. Demographics, comorbid diseases, clinical data, severity of illness [the sequential organ failure assessment (SOFA) score, number of vasopressors, diagnosis of sepsis, use of ventilator] upon ICU admission, fluid overload status, and time elapsed from AKI diagnosis until CRRT initiation were reviewed from the medical charts.ResultsPatients with total fluid overload from 3 days before CRRT initiation to ICU discharge had a significantly lower survival rate after ICU admission, as compared to patients with no fluid overload (P < 0.001). Among patients with sepsis (P < 0.001) or with high SOFA scores (P < 0.001), there was a significant difference in survival of the patients with and without fluid overload. In patients without sepsis or with low SOFA score, there was no significant difference in survival of patients irrespective of fluid overload.ConclusionOur study demonstrates that the adverse effect of fluid overload on survival is more evident in patients with sepsis or with more severe illness, and that it might not apply to patients without sepsis or with less severe illness.

IntroductionFluid overload is a well-known predictor of mortality in patients with acute kidney injury (AKI). Multifrequency bioimpedance analysis (MF-BIA) is a promising tool for quantifying volume status. However, few studies have analyzed the effect of MF-BIA-defined volume status on the mortality of critically ill patients with AKI. This retrospective medical research study aimed to investigate this issue.MethodsWe retrospectively reviewed the medical records of patients with AKI who underwent continuous veno-venous hemodiafiltration (CVVHDF) from Jan. 2013 to Feb. 2014. Female patients were excluded to control for sex-based differences. Volume status was measured using MF-BIA (Inbody S20, Seoul, Korea) at the time of CVVHDF initiation, and volume parameters were adjusted with height squared (H2). Binary logistic regression analyses were performed to test independent factors for prediction of in-hospital mortality.ResultsA total of 208 male patients were included in this study. The mean age was 65.19±12.90 years. During the mean ICU stay of 18.29±27.48 days, 40.4% of the patients died. The in-hospital mortality rate increased with increasing total body water (TBW)/H2 quartile. In the multivariable analyses, increased TBW/H2 (OR 1.312(1.009-1.705), p=0.043) and having lower serum albumin (OR 0.564(0.346-0.919, p=0.022) were independently associated with higher in-hospital mortality. When the intracellular water (ICW)/H2 or extracellular water (ECW)/H2 was adjusted instead of the TBW/H2, only excess ICW/H2 was independently associated with increased mortality (OR 1.561(1.012-2.408, p=0.044).ConclusionsMF-BIA-defined excess TBW/H2 and ICW/H2 are independently associated with higher in-hospital mortality in male patients with AKI undergoing CVVHDF.

BackgroundThe world’s population is aging faster and the incidence of acute kidney injury (AKI) needing continuous renal replacement therapy (CRRT) is increasing in elderly population. The outcome of AKI needing CRRT in elderly patients is known to be poor. However, the definitions of elderly used in the previous literatures were diverse and, there were few data that compared the long-term mortality rates of these patients with middle aged patients. This study was aimed to evaluate this issue.MethodsThis study was a single-center, retrospective cohort study of patients who underwent CRRT from January 2013 to December 2015. The patients were divided into the following four age cohorts: middle-aged (55–64), young-old (65–74), middle-old (75–84), and old-old (≥85). The short- and long-term mortality rates for each age cohort were compared.ResultsA total of 562 patients met the inclusion criteria. The short-term mortality rate was 57.3% in the entire cohort. Compared with the middle-aged cohort, the middle-old cohort (HR 1.48 (1.09–2.02), p = 0.012) and the old-old cohort (HR 2.33 (1.30–4.19), p = 0.005) showed an increased short-term mortality rate along with an increased SOFA score, acidemia and a prolonged prothrombin time. When we analyzed the long-term mortality rate of the 238 survived patients, the middle-old cohort (HR 3.76 (1.84–7.68), p<0.001), the old-old cohort (HR 4.40(1.20–16.10), p = 0.025), a lower BMI, the presence of liver cirrhosis, the presence of congestive heart failure and a history of sepsis were independent risk factors for the prediction of long-term mortality.ConclusionCompared with the middle-aged cohort, the middle-old and the old-old cohort showed an increased short-term and long-term mortality rate. However, in the young-old cohort, neither the short-term nor the long-term mortality rate was increased.