CD147 mediates the CD44s-dependent differentiation of myofibroblasts driven by transforming growth factor-ß1.

Progressive fibrosis leads to loss of organ function and affects many organs as a result of excessive extracellular matrix production. The ubiquitous matrix polysaccharide hyaluronan (HA) is central to this through association with its primary receptor, CD44, which exists as standard CD44 (CD44s) or multiple splice variants. Mediators such as profibrotic transforming growth factor (TGF)-ß1 and proinflammatory interleukin (IL)-1ß are widely associated with fibrotic progression. TGF-ß1 induces myofibroblast differentiation, while IL-1ß induces a proinflammatory fibroblast phenotype that promotes fibroblast binding to monocyte/macrophages. CD44 expression is essential for both responses. Potential CD44 splice variants involved, however, are unidentified. The TGF-ß1-activated CD44/epidermal growth factor receptor complex induces differentiation of metastatic cells through interactions with the matrix metalloproteinase inducer, CD147. This study aimed to determine the CD44 variants involved in TGF-ß1- and IL-1ß-mediated responses and to investigate the potential profibrotic role of CD147. Using immunocytochemistry and quantitative PCR, standard CD44s were shown to be essential for both TGF-ß1-induced fibroblast/myofibroblast differentiation and IL-1ß-induced monocyte binding. Co-immunoprecipitation identified that CD147 associated with CD44s. Using CD147-siRNA and confocal microscopy, we also determined that incorporation of the myofibroblast marker, αSMA, into F-actin stress fibers was prevented in the absence of CD147 and myofibroblast-dependent collagen gel contraction was inhibited. CD147 did not associate with HA, but removal of HA prevented the association of CD44s with CD147 at points of cell-cell contact. Taken together, our data suggest that CD44s/CD147 colocalization is essential in regulating the mechanical tension required for the αSMA incorporation into F-actin stress fibers that regulates myofibroblast phenotype.

Hyaluronidase-2 Regulates RhoA Signaling, Myofibroblast Contractility, and Other Key Profibrotic Myofibroblast Functions.

Hyaluronidase (HYAL)-2 is a weak, acid-active, hyaluronan-degrading enzyme broadly expressed in somatic tissues. Aberrant HYAL2 expression is implicated in diverse pathology. However, a significant proportion of HYAL2 is enzymatically inactive; thus the mechanisms through which HYAL2 dysregulation influences pathobiology are unclear. Recently, nonenzymatic HYAL2 functions have been described, and nuclear HYAL2 has been shown to influence mRNA splicing to prevent myofibroblast differentiation. Myofibroblasts drive fibrosis, thereby promoting progressive tissue damage and leading to multimorbidity. This study identifies a novel HYAL2 cytoplasmic function in myofibroblasts that is unrelated to its enzymatic activity. In fibroblasts and myofibroblasts, HYAL2 interacts with the GTPase-signaling small molecule ras homolog family member A (RhoA). Transforming growth factor beta 1-driven fibroblast-to-myofibroblast differentiation promotes HYAL2 cytoplasmic relocalization to bind to the actin cytoskeleton. Cytoskeletal-bound HYAL2 functions as a key regulator of downstream RhoA signaling and influences profibrotic myofibroblast functions, including myosin light-chain kinase-mediated myofibroblast contractility, myofibroblast migration, myofibroblast collagen/fibronectin deposition, as well as connective tissue growth factor and matrix metalloproteinase-2 expression. These data demonstrate that, in certain biological contexts, the nonenzymatic effects of HYAL2 are crucial in orchestrating RhoA signaling and downstream pathways that are important for full profibrotic myofibroblast functionality. In conjunction with previous data demonstrating the influence of HYAL2 on RNA splicing, these findings begin to explain the broad biological effects of HYAL2.

Acute kidney injury demographics and outcomes: changes following introduction of electronic acute kidney injury alerts-an analysis of a national dataset.

BACKGROUND: Electronic alerts for acute kidney injury (AKI) have been widely advocated. Our aim was to describe the changes in AKI demographics and outcomes following implementation of a national electronic AKI alert programme. METHODS: A prospective national cohort study was undertaken to collect data on all cases of AKI in adult patients (≥18 years of age) between 1 April 2015 and 31 March 2019. RESULTS: Over the period of data collection, there were 193 838 AKI episodes in a total of 132 599 patients. The lowest incidence of AKI was seen in the first year after implementation of electronic alerts. A 30-day mortality was highest in Year 1 and significantly lower in all subsequent years. A direct comparison of mortality in Years 1 and 4 demonstrated a significantly increased relative risk (RR) of death in Year 1: RR = 1.08 [95% confidence interval (CI) 1.054-1.114 P < 0.001]. This translates into a number needed to treat in Year 4 for one additional patient to survive of 69.5 (95% CI 51.7-106.2) when directly comparing the outcomes across the 2 years. The increase in the number of cases and improved outcomes was more pronounced in community-acquired AKI, and was associated with a significant increase in patient hospitalization. CONCLUSIONS: This study represents the first large-scale dataset to clearly demonstrate that a national AKI alerting system which highlights AKI is associated with a change in both AKI demographics and patient outcomes.

Derivation of a prediction model for emergency department acute kidney injury.

BACKGROUND AND OBJECTIVE: Quality management of Acute Kidney Injury (AKI) is dependent on early detection, which is currently deemed to be suboptimal. The aim of this study was to identify combinations of variables associated with AKI and to derive a prediction tool for detecting patients attending the emergency department (ED) or hospital with AKI (ED-AKI). DESIGN, SETTING, PARTICIPANTS AND MEASUREMENTS: This retrospective observational study was conducted in the ED of a tertiary university hospital in Wales. Between April and August 2016 20,421 adult patients attended the ED of a University Hospital in Wales and had a serum creatinine measurement. Using an electronic AKI reporting system, 548 incident adult ED-AKI patients were identified and compared to a randomly selected cohort of adult non-AKI ED patients (n = 571). A prediction model for AKI was derived and subsequently internally validated using bootstrapping. The primary outcome measure was the number of patients with ED-AKI. RESULTS: In 1119 subjects, 27 variables were evaluated. Four ED-AKI models were generated with C-statistics ranging from 0.800 to 0.765. The simplest and most practical multivariate model (model 3) included eight variables that could all be assessed at ED arrival. A 31-point score was derived where 0 is minimal risk of ED-AKI. The model discrimination was adequate (C-statistic 0.793) and calibration was good (Hosmer & Lomeshow test 27.4). ED-AKI could be ruled out with a score of <2.5 (sensitivity 95%). Internal validation using bootstrapping yielded an optimal Youden index of 0.49 with sensitivity of 80% and specificity of 68%. CONCLUSION: A risk-stratification model for ED-AKI has been derived and internally validated. The discrimination of this model is objective and adequate. It requires refinement and external validation in more generalisable settings.

Acute Kidney Injury in Children Based on Electronic Alerts.

OBJECTIVE: To define the incidence and outcome of acute kidney injury (AKI) in pediatrics using data collected from a national electronic alert system. STUDY DESIGN: A prospective national cohort study was undertaken to collect data on all cases of pediatric AKI, excluding neonates, identified by an e-alert, from April 2015 to March 2019. RESULTS: There were 2472 alerts in a total of 1719 patients, giving an incidence of 77.3 per 100 000 person-years. Of the patients, 84.2% of all AKI were stage 1 and 58.3% occurred with a triggering creatinine within the reference range. The incidence of AKI was associated with measures of social deprivation. Thirty-day mortality was 1.7% but was significantly higher in hospital-acquired AKI (2.1%), compared with community-acquired AKI (0.8%, P < .001) and was associated with the severity of AKI at presentation. A significant proportion of patients had no repeat measure of creatinine (39.8%). This was higher in community-acquired AKI (69.7%) compared with hospital-acquired AKI (43.0%, P < .001), and higher in patients alerting with patients triggering with a creatinine within the reference range (48.4% vs 24.5%, P < .001). The majority of patients (84.7%) experienced only 1 AKI episode. Repeated episodes of AKI were associated with increased 30-mortaltiy (11.6% vs 4.6%, P < .001) and higher residual renal impairment (13.3% vs 5.4%, P < .001). CONCLUSIONS: The results suggest that the significance of the alert is missed in many cases reflecting that a large proportion of cases represent modest elevations in serum creatinine (SCr), triggered by a SCr level that may be interpreted as being normal despite a significant increase from the baseline for the patient.

Recurrent acute kidney injury: predictors and impact in a large population-based cohort.

BACKGROUND: This study examined the impact of recurrent episodes of acute kidney injury (AKI) on patient outcomes. METHODS: The Welsh National electronic AKI reporting system was used to identify all cases of AKI in patients ≥18 years of age between April 2015 and September 2018. Patients were grouped according to the number of AKI episodes they experienced with each patient's first episode described as their index episode. We compared the demography and patient outcomes of those patients with a single AKI episode with those patients with multiple AKI episodes. Analysis included 153 776 AKI episodes in 111 528 patients. RESULTS: Of those who experienced AKI and survived their index episode, 29.3% experienced a second episode, 9.9% a third episode and 4.0% experienced fourth or more episodes. Thirty-day mortality for those patients with multiple episodes of AKI was significantly higher than for those patients with a single episode (31.3% versus 24.9%, P < 0.001). Following a single episode, recovery to baseline renal function at 30 days was achieved in 83.6% of patients and was significantly higher than for patients who had repeated episodes (77.8%, P < 0.001). For surviving patients, non-recovery of renal function following any AKI episode was significantly associated with a higher probability of a further AKI episode (33.4% versus 41.0%, P < 0.001). Furthermore, with each episode of AKI the likelihood of a subsequent episode also increased (31.0% versus 43.2% versus 51.2% versus 51.7% following a first, second, third and fourth episode, P < 0.001 for all comparisons). CONCLUSIONS: The results of this study provide an important contribution to the debate regarding the need for risk stratification for recurrent AKI. The data suggest that such a tool would be useful given the poor patient and renal outcomes associated with recurrent AKI episodes as highlighted by this study.

Epidemiology of emergency department acute kidney injury.

AIM: The epidemiology of acute kidney injury (AKI) diagnosed in the emergency department (ED) is poorly described. This study describes the incidence, demographics and outcomes of patients diagnosed with AKI in the ED (ED-AKI). METHODS: A prospective cohort study was completed in a University Teaching Hospital, (UK) between April and August 2016. In total, 20 421 adult patients attended the ED and had a serum creatinine measurement. The incident ED-AKI patient episodes were compared with a randomly selected cohort of non-AKI ED patients. RESULTS: A total of 572 patients had confirmed eAlert ED-AKI (548 incident cases), incidence 2.8% (of all ED attendances). ED-AKI was associated with a 24.4% in-patient mortality (non-AKI 3.2%, P < .001) of which 22.3% of deaths occurred within 24 hours and 58% within 7 days. Progression of the admission AKI stage to a higher AKI stage was associated with a 38.8% mortality compared with a 21.4% mortality in those who did not progress (P < .001). In multivariate analysis, ED-AKI was an independent risk for mortality (hazard ratio, 6.293; 95% confidence interval, 1.887-20.790, P = .003). For those discharged from hospital, 20.4% of ED-AKI patients re-attend for acute assessment within 30-days post-discharge (non-AKI 7.6%, P < .001). At 90-days post-discharge, 10.0% of ED-AKI patients died (non-AKI 1.4%, P < .001). Twelve months post-discharge 17.8% of ED-AKI patients developed CKD progression or de-novo CKD (non-AKI 6.0%). CONCLUSION: The ED-AKI is an independent predictor of death. Mortality is predominantly in the early stages of hospital admission, but for those who survive to discharge have significant long-term morbidity and mortality.

Tumor Necrosis Factor-stimulated Gene 6 (TSG-6)-mediated Interactions with the Inter-α-inhibitor Heavy Chain 5 Facilitate Tumor Growth Factor ß1 (TGFß1)-dependent Fibroblast to Myofibroblast Differentiation.

Fibroblasts are central to wound healing and fibrosis through TGFß1-triggered differentiation into contractile, α-smooth muscle actin (α-SMA)-positive myofibroblasts. This is mediated by accumulation of a pericellular matrix of hyaluronan (HA) and the HA-dependent co-localization of CD44 with the epidermal growth factor receptor (EGFR). Interactions of HA with hyaladherins, such as inter-α-inhibitor (IαI) and tumor necrosis factor-stimulated gene-6 (TSG-6), are also essential for differentiation. This study investigated the mechanisms involved. TSG-6 and α-SMA had different kinetics of induction by TGFß1, with TSG-6 peaking before α-SMA Si CD44 or EGFR inhibition prevented differentiation but had no effect on TSG-6 expression. TSG-6 was essential for differentiation, and mAb A38 (preventing IαI heavy chain (HC) transfer), HA-oligosaccharides, cobalt, or Si bikunin prevented TSG-6 activity, preventing differentiation. A38 also prevented the EGFR/CD44 association. This suggested that TSG-6/IαI HC interaction was necessary for the effect of TSG-6 and that HC stabilization of HA initiated the CD44/EGFR association. The newly described HC5 was shown to be the principal HC expressed, and its cell surface expression was prevented by siRNA inhibition of TSG-6 or bikunin. HC5 was released by hyaluronidase treatment, confirming its association with cell surface HA. Finally, HC5 knockdown by siRNA confirmed its role in myofibroblast differentiation. The current study describes a novel mechanism linking the TSG-6 transfer of the newly described HC5 to the HA-dependent control of cell phenotype. The interaction of HC5 with cell surface HA was essential for TGFß1-dependent differentiation of fibroblasts to myofibroblasts, highlighting its importance as a novel potential therapeutic target.

The incidence of pediatric acute kidney injury is increased when identified by a change in a creatinine-based electronic alert.

A prospective national cohort study was undertaken to collect data on all cases of pediatric (under 18 yrs of age) acute kidney injury (AKI) identified by a biochemistry-based electronic alert using the Welsh National electronic AKI reporting system. Herein we describe the utility and limitation of using this modification of the KDIGO creatinine-based system data set to characterize pediatric AKI. Of 1,343 incident episodes over a 30-month period, 34.5% occurred in neonates of which 83.8% were AKI stage 1. Neonatal 30-day mortality was 4.1%, with 73.3% of this being accounted for by patients treated in an Intensive Care Unit. In the non-neonatal group, 76.1% were AKI stage 1. Hospital-acquired AKI accounted for 40.1% of episodes while community-acquired AKI represented 29.4% of cases within which 33.9% were admitted to hospital and 30.5% of cases were unclassified. Non-neonatal 30-day mortality was 1.2%, with half of this accounted for by patients treated in the Intensive Care Unit. Nonrecovery of renal function at 30 days occurred in 28% and was significantly higher in patients not admitted to hospital (45% vs. 20%). The reported incidence of AKI in children was far greater than previously reported in studies reliant on clinical identification of adult AKI or hospital coding data. Mortality was highest in neonates and driven by those in the Intensive Care Unit. Nonrecovery of renal function and persistent renal impairment was more common in non-neonates and was especially high in patients with community-acquired AKI who were not hospitalized.

Seasonal pattern of incidence and outcome of Acute Kidney Injury: A national study of Welsh AKI electronic alerts.

OBJECTIVES: To identify any seasonal variation in the occurrence of, and outcome following Acute Kidney Injury. METHODS: The study utilised the biochemistry based AKI electronic (e)-alert system established across the Welsh National Health Service to collect data on all AKI episodes to identify changes in incidence and outcome over one calendar year (1st October 2015 and the 30th September 2016). RESULTS: There were total of 48 457 incident AKI alerts. The highest proportion of AKI episodes was seen in the quarter of January to March (26.2%), and the lowest in the quarter of October to December (23.3%, P < .001). The same trend was seen for both community-acquired and hospital-acquired AKI sub-sets. Overall 90 day mortality for all AKI was 27.3%. In contrast with the seasonal trend in AKI occurrence, 90 day mortality after the incident AKI alert was significantly higher in the quarters of January to March and October to December compared with the quarters of April to June and July to September (P < .001) consistent with excess winter mortality reported for likely underlying diseases which precipitate AKI. CONCLUSIONS: In summary we report for the first time in a large national cohort, a seasonal variation in the incidence and outcomes of AKI. The results demonstrate distinct trends in the incidence and outcome of AKI.

Hyaluronan regulates bone morphogenetic protein-7-dependent prevention and reversal of myofibroblast phenotype.

Hyaluronan (HA) promotes transforming growth factor (TGF)-ß1-driven myofibroblast phenotype. However, HA can also have disease-limiting activity. Bone morphogenetic protein-7 (BMP7) is an antifibrotic cytokine that antagonizes TGF-ß1, and isolated studies have demonstrated that HA can both mediate and modulate BMP7 responses. In this study, we investigated whether BMP7 can modulate HA in a manner that leads to prevention/reversal of TGF-ß1-driven myofibroblast differentiation in human lung fibroblasts. Results demonstrated that BMP7 prevented and reversed TGF-ß1-driven myofibroblast differentiation through a novel mechanism. BMP7 promoted the dissolution and internalization of cell-surface HA into cytoplasmic endosomes. Endosomal HA co-localized with the HA-degrading enzymes, hyaluronidase-1 and hyaluronidase-2 (Hyal2). Moreover, BMP7 showed differential regulation of CD44 standard and variant isoform expression, when compared with TGF-ß1. In particular, BMP7 increased membrane expression of CD44v7/8. Inhibiting CD44v7/8 as well as blocking Hyal2 and the Na(+)/H(+) exchanger-1 at the cell-surface prevented BMP7-driven HA internalization and BMP7-mediated prevention/reversal of myofibroblast phenotype. In summary, a novel mechanism of TGF-ß1 antagonism by BMP7 is shown and identifies alteration in HA as critical in mediating BMP7 responses. In addition, we identify Hyal2 and CD44v7/8 as new potential targets for manipulation in prevention and reversal of fibrotic pathology.

The impact of acute kidney injury in diabetes mellitus.

BACKGROUND: Little data exist on outcome of acute kidney injury (AKI) in diabetes. We describe short-term recovery of renal function, patient mortality and progressive renal dysfunction following AKI in diabetic patients. METHODS: Using the diagnosis of either diabetes or no diabetes as the defining variable, AKI episodes were identified from records of a clinical biochemistry department serving a population of 560 000. Patient co-morbidity and mortality were collated from electronic patient records. Outcomes were compared with a non-diabetic cohort with AKI. RESULTS: Acute kidney injury was identified in 101 diabetic and 392 non-diabetic patients. Patients with diabetes had less severe AKI, compared with the non-diabetic cohort (AKI stage 1 76% vs 55%, P = 0.0006). Overall acute mortality, and mortality adjusted for co-morbidity, was comparable in the diabetic and non-diabetic groups. Recovery to baseline renal function was greater in diabetic patients (87% vs 63% P = 0.001), and the proportion of patients developing progressive chronic kidney disease was lower in the (14%) compared with the non-diabetic cohort (48%, P < 0.00001). CONCLUSIONS: Although acute mortality is comparable following an AKI episode in diabetic patients compared with that associated with AKI in a non-diabetic cohort, for those surviving the acute episode, its impact on renal function is significantly less than in a non-diabetic group.

miR-192 induces G2/M growth arrest in aristolochic acid nephropathy.

Aristolochic acid nephropathy is characterized by rapidly progressive tubulointerstitial nephritis culminating in end-stage renal failure and urothelial malignancy. Profibrotic effects of aristolochic acid are linked to growth arrest of proximal tubular epithelial cells; however, the underlying mechanisms are largely undetermined. miRNAs are small, endogenous, post-transcriptional regulators of gene expression implicated in numerous physiological and pathological processes. In the present study, we characterized the mechanism of aristolochic acid-induced cell cycle arrest and its regulation by miRNAs. Incubation with aristolochic acid led to profound G2/M arrest in proximal tubular epithelial cells via p53-mediated inactivation of the maturation-promoting complex, CDK1/cyclin-B1. Analysis of miRNA expression identified up-regulation of miRNAs, including miR-192, miR-194, miR-450a, and miR-542-3p. The stable overexpression of miR-192 recapitulated G2/M arrest via repression of the E3 ubiquitin ligase, murine double-minute 2, a negative regulator of p53. p53-induced transcription of p21(cip1) and growth arrest and DNA damage 45 and resulted in the inactivation and dissociation of the maturation-promoting complex. These data demonstrate a core role for miR-192 in mediating proximal tubular epithelial cell G2/M arrest after toxic injury by aristolochic acid. Because numerous studies have linked such growth arrest to fibrosis after proximal tubular epithelial cell injury, this mechanism may have widespread relevance to recovery/nonrecovery after acute kidney injury.

Transforming growth factor-ß1 (TGF-ß1)-stimulated fibroblast to myofibroblast differentiation is mediated by hyaluronan (HA)-facilitated epidermal growth factor receptor (EGFR) and CD44 co-localization in lipid rafts.

Fibroblast to myofibroblast differentiation drives effective wound healing and is largely regulated by the cytokine transforming growth factor-ß1 (TGF-ß1). Myofibroblasts express α-smooth muscle actin and are present in granulation tissue, where they are responsible for wound contraction. Our previous studies show that fibroblast differentiation in response to TGF-ß1 is dependent on and mediated by the linear polysaccharide hyaluronan (HA). Both the HA receptor, CD44, and the epidermal growth factor receptor (EGFR) are involved in this differentiation response. The aim of this study was to understand the mechanisms linking HA-, CD44-, and EGFR-regulated TGF-ß1-dependent differentiation. CD44 and EGFR co-localization within membrane-bound lipid rafts was necessary for differentiation, and this triggered downstream mitogen-activated protein kinase (MAPK/ERK) and Ca(2+)/calmodulin kinase II (CaMKII) activation. We also found that ERK phosphorylation was upstream of CaMKII phosphorylation, that ERK activation was necessary for CaMKII signaling, and that both kinases were essential for differentiation. In addition, HA synthase-2 (HAS2) siRNA attenuated both ERK and CaMKII signaling and sequestration of CD44 into lipid rafts, preventing differentiation. In summary, the data suggest that HAS2-dependent production of HA facilitates TGF-ß1-dependent fibroblast differentiation through promoting CD44 interaction with EGFR held within membrane-bound lipid rafts. This induces MAPK/ERK, followed by CaMKII activation, leading to differentiation. This pathway is synergistic with the classical TGF-ß1-dependent SMAD-signaling pathway and may provide a novel opportunity for intervention in wound healing.

Epidemiology and outcome of community-acquired acute kidney injury.

AIMS: Very little data exist regarding community-acquired acute renal injury (CA-AKI). We have identified and characterized a patient cohort with CA-AKI, and documented its impact on renal function and patient mortality. METHODS: Using the database of the Medical Biochemistry Department of the Cardiff and Vale University Health Board we identified all patients with CA-AKI over a 1 month period in 2009. Follow-up biochemical and clinical data were used to determine short-term (3 months) and long-term (3 years) outcomes. Comparisons were made to a random and an age/sex matched group. RESULTS: Patients with CA-AKI were older than a non-AKI cohort (70.3 vs 57.1 years; P < 0.0001), with a 61% male predominance. 38% had pre-existing chronic kidney disease (CKD) compared with 25% in the age- and sex-matched non-CA-AKI cohort (P = 0.007). 54% of CA-AKI were admitted for inpatient care. Admission was associated with a higher incidence of complete recovery of renal function. Mortality at 3 months was 16.5%, and was related to the severity of AKI. Over the 3 years of follow-up 71% of patients with CA-AKI developed progressive CKD which was more likely following incomplete/no recovery of renal function and in the context of pre-existing CKD. Three year mortality was 45%, which was higher than that of the age/sex matched control cohort (15.7%; P < 0.0001), but was not related to the development of progressive CKD. CONCLUSIONS: CA-AKI carries significant implications in terms of both development of progressive renal disease and high long-term patient mortality.

Renal impairment among acute hospital admissions in a rural Ethiopian hospital.

AIM: Acute renal injury (AKI) is a relatively common clinical condition, reported to be associated with high rates of in-hospital mortality. Although here is an extensive literature on the nature and consequence of AKI in the developed World, much less is known in the developing World and more specifically in sub-Saharan Africa, which is addressed directly in this study. METHODS: We describe the prevalence, clinical characteristics and impact of AKI in patients admitted to a single centre in Ethiopia with no dedicated renal services. RESULTS: Renal function tests are not preformed routinely in many Ethiopian hospitals. This occurred in 32% of all patients in this study, falling to 23% on surgical wards. As a consequence no cases of AKI were identified in the context of surgical admissions. AKI was only identified in a cohort of patients on medical wards, with a prevalence of roughly 20% of medical patients in which renal function was measured. The patients with AKI were younger than those at risk of AKI in studies from the developed World but were older than those who did not develop AKI in this study. In the majority of cases AKI could be considered to be pre-renal in its origin. In contrast to studies in the developed World, AKI did not adversely impact on either duration of hospital stay or on patient mortality. Residual renal impairment was, however, common at the point of discharge. CONCLUSION: The data suggest subtle differences in the nature and impact of AKI between those published and mainly derived from the developed world and patients in sub-Saharan Africa.

Transforming growth factor ß1 represses proximal tubular cell microRNA-192 expression through decreased hepatocyte nuclear factor DNA binding.

miR (microRNA)-192 plays key roles in renal pathological and physiological responses, by repressing targets including Zeb1, Zeb2 and Wnk1. In the present study, we have assessed the regulation of miR-192 expression. We found that TGF-ß1 (transforming growth factor ß1) down-regulates miR-192 and miR-194, co-transcribed in the shared precursor pri-miR (primary miR transcript)-192/194. Luciferase reporter analysis showed constitutive promoter activity within nucleotides +21 to -223. We identified HNF (hepatocyte nuclear factor) and p53 binding sites within this region that were required for constitutive promoter activity, which was decreased by TGF-ß1 through an Alk5-dependent mechanism. TGF-ß1 treatment decreased HNF binding to the miR-194-2/192 promoter, whereas knockdown of HNF-1 inhibited mature miR-192 and miR-194 expression. miR-192, miR-194 and HNF expression were restricted to a defined subset of human tissues including kidney, small intestine, colon and liver. Our results from the present study identify co-ordinated regulation of miR-192 and miR-194, with binding of HNF and p53 transcription factors necessary for activation of transcription, and TGF-ß1-mediated repression through decreased HNF binding to its cognate promoter element.

Diabetes and renal disease: who does what?

Care of patients with diabetes and chronic kidney disease (CKD) in the UK is divided between primary care, diabetologists and nephrology. In a retrospective analysis, we examined the distribution of care provision for patients with diabetes and CKD. Nephrology services see a minority of diabetic patients with CKD, but they see the majority of those with an estimated glomerular filtration rate (eGFR) of <30 ml/min. Of those followed in nephrology, 70% showed no evidence of progressive renal dysfunction. The nephrology cohort were significantly younger that those seen by primary care physicians or diabetologists. Half of the patients with diabetes and CKD seen in either the primary care and diabetology cohorts, with no nephrology input, had a rate of fall of eGFR of >5 ml/min/yr. This suggests that older age might deter referral to nephrology, which is based predominantly on CKD stage. This results in a significant proportion of patients with stable renal function being seen by nephrology, and in the under-referral of a large cohort of patients with progressive CKD.

Prevalence of risk factors for foot ulceration in a general haemodialysis population.

It is well documented that diabetic foot ulceration contributes to increased morbidity and mortality associated with renal replacement therapy. Much less is known about the risk of foot ulceration and lower limb amputation in the non-diabetic dialysis population. The aim of this study was to determine if the prevalence of risks factors for lower limb amputation in a stable haemodialysis population was greater in the diabetic cohort compared with the non-diabetic cohort. The study design is a prospective observational cohort study. Sixty patients attending a satellite haemodialysis unit in Cardiff were invited to have a comprehensive foot assessment as part of a Podiatry service review. The medical notes and hospital information system were used to identify the diabetic cohort. Patients were classified according to diabetic status (diabetic versus non-diabetic). The Renal Foot Screening Tool was developed to prospectively identify risk factors associated with foot ulceration. The assessment included peripheral neuropathy (PN), peripheral arterial disease (PAD) and foot pathology (FP). Fifty-seven patients gave informed verbal consent prior to inclusion. Risk factors for foot ulceration were recorded at baseline in the diabetic (n = 24) and non-diabetic (n = 33) groups and mortality data was revisited after a 3-year period. FP was identified in 79% of patients. Eighteen per cent of the non-diabetic patients had PN. PAD was identified in 45% of diabetic and 30% of non-diabetic patients. Forty-nine per cent of the total cohort had ≥2 of the 3 independent risk factors for foot ulceration (16/24 diabetic versus 12/33 non-diabetic). The presence of PAD and PN was predictive of mortality independent of age. The limitations of this study are its small sample size and patients were from a single satellite dialysis unit. There was a high prevalence of risk factors for foot ulceration in this population, which were not confined to the diabetic cohort. These findings suggest that non-diabetic patients on haemodialysis therapy are also at risk of developing foot ulceration. Further work on strategies to monitor and prevent FP in this high-risk cohort is needed to minimize morbidity and mortality associated with foot ulceration.

Hyaluronan facilitates transforming growth factor-ß1-dependent proliferation via CD44 and epidermal growth factor receptor interaction.

Fibroblast proliferation is an early feature of progressive tissue fibrosis and is largely regulated by the cytokine transforming growth factor-ß1 (TGF-ß1). In the oral mucosa, fibroblasts have a unique phenotype and demonstrate healing with no fibrosis/scarring. Our previous studies show that whereas dermal fibroblasts proliferate in response to TGF-ß1, oral fibroblasts have an antiproliferative response to this cytokine. Hyaluronan (HA) was directly linked to this TGF-ß1-dependent response. The aim of this study was to understand the underlying mechanism through which HA regulates TGF-ß-dependent responses. Using patient-matched oral and dermal fibroblasts, we show that TGF-ß1-dependent proliferation is mediated through the HA receptor CD44, whereas the TGF-ß1-mediated antiproliferative response is CD44-independent. Furthermore, overexpression of HAS2 (HA synthase-2) in oral cells modifies their response, and they subsequently demonstrate a proliferative, CD44-dependent response to TGF-ß1. We also show that epidermal growth factor (EGF) and its receptor (EGFR) are essential for TGF-ß1/HA/CD44-dependent proliferation. Increased HA levels promote EGFR and CD44 coupling, potentiating signal transduction through the MAPK/ERK pathway. Thus, in a HA-rich environment, late ERK1/2 activation results from EGFR/CD44 coupling and leads to a proliferative response to TGF-ß1. In comparison, in a non-HA-rich environment, only early ERK1/2 activation occurs, and this is associated with an antiproliferative response to TGF-ß1. In summary, HA facilitates TGF-ß1-dependent fibroblast proliferation through promoting interaction between CD44 and EGFR, which then promotes specific MAPK/ERK activation, inducing cellular proliferation.