Carol A. Pollock

Background: Insulin is a mainstay treatment for diabetes, but its use is associated with weight gain and hypoglycaemia. Data on the effects of sodium-glucose cotransporter 2 (SGLT2) inhibitors on insulin use in people with chronic kidney disease (CKD) is limited. Methods: We conducted a post-hoc analysis of the CREDENCE (Canagliflozin and Renal Events in Diabetes with Established Nephropathy Clinical Evaluation) trial. Effects of canagliflozin versus placebo on insulin use (initiation, dose intensification, reduction and discontinuation) in people with CKD and type 2 diabetes were evaluated using Cox regression models. The primary outcome was insulin initiation or >25% insulin dose intensification (in those not receiving and receiving insulin at baseline, respectively). Effects on kidney, cardiovascular and safety outcomes by baseline insulin use were also assessed. Results: Among 4401 participants, 2884 (65.5%) were receiving insulin at baseline; these participants were more likely to have lower estimated glomerular filtration rate, higher albuminuria and longer duration of diabetes (all P<0.001). Over a median on-treatment period of 2.0 years, canagliflozin reduced the need for insulin initiation or >25% dose intensification by 19% compared to placebo (HR 0.81, 95% CI 0.71-0.93), irrespective of baseline kidney function or albuminuria (both P-interaction>0.10). Sustained insulin dose reductions of >50% were achieved more frequently with canagliflozin than placebo (HR 1.49, 95% CI 1.15-1.91), although no difference in insulin discontinuation was observed between treatment arms. Effects of canagliflozin on kidney, cardiovascular and safety outcomes were consistent regardless of baseline insulin use (all P-interaction>0.05). Conclusions: In CKD and type 2 diabetes, canagliflozin reduces insulin use with consistent effects regardless of baseline kidney function. This supports the use of canagliflozin in people with CKD, not only for end organ protection, but also to improve glycaemic control and reduce exposure to insulin and its associated adverse effects.

NEDD4-2, a ubiquitin ligase, regulates a number of ion channels and transporters by promoting their ubiquitination, internalisation and degradation, thereby affecting many signalling and physiological outcomes. Loss of this gene in mice results in tubular cell death and a chronic kidney disease (CKD)-like phenotype due to aberrant Na+ transport, caused by elevated expression of NEDD4-2 substrates including the epithelial sodium channel (ENaC). One of the biggest risk factors for CKD is diabetes, as up to 50% of diabetic patients develop diabetic kidney disease (DKD). Reduced levels of Nedd4-2 are associated with DKD in patients, therefore we investigated if this gene contributes to the development of this disease. In a diabetic (db/db) mouse model that develops DKD, we observed reduced expression of Nedd4-2 that correlated with disease progression. Substrates of NEDD4-2, including ENaC, were elevated in db/db mice, suggesting that NEDD4-2 dysfunction is involved in disease pathology. Intriguingly, genetic ablation of Nedd4-2 in this diabetic model did not exacerbate kidney disease severity beyond Nedd4-2 loss alone, but corrected metabolic parameters via a reduction of aldosterone levels, restoration of insulin signaling and reduced blood glucose levels. Hence, we conclude that a reduced Nedd4-2 level is detrimental for kidney health, however unexpectedly improves glycemic control in diabetes.

Background: Unplanned hospitalization, irrespective of cause, is a meaningful outcome for patients, caregivers, clinicians and health systems. The effects of sodium-glucose cotransporter 2 (SGLT2) inhibitors on all-cause hospitalization in patients with chronic kidney disease (CKD) has not been systematically evaluated. Methods: We conducted a post-hoc analysis of the Canagliflozin and Renal Events in Diabetes with Established Nephropathy Clinical Evaluation (CREDENCE) trial to evaluate the effect of canagliflozin on non-elective all-cause hospitalization using Cox proportional hazards models, with recurrent events analysis to assess effects on first and subsequent hospitalizations. We performed inverse variance weighted meta-analysis of three placebo-controlled SGLT2 inhibitor CKD-focused trials to assess the relative and absolute effects of SGLT2 inhibitors on first and subsequent all-cause hospitalizations overall and across clinically relevant subgroups. For analyses of cause-specific hospitalization, adverse events that were reported by investigators but not adjudicated were used. Results: Over a median follow-up of 2.6 years, 3015 hospitalizations occurred among 1543 of 4401 (35%) participants in the CREDENCE trial. Compared with placebo, canagliflozin reduced the risk of first all-cause hospitalization (hazarrd ratio [HR] 0.88, 95% confidence interval [CI] 0.80-0.98; p=0.02) and first and subsequent hospitalizations (HR 0.86, 95% CI 0.76-0.96; p=0.007). In a meta-analysis of three placebo-controlled SGLT2 inhibitor CKD-focused trials, SGLT2 inhibitors reduced the risk of first and subsequent hospitalizations from any cause by 15% (HR 0.85, 95% CI 0.78-0.95; p<0.001), with consistent effects irrespective of diabetes, baseline kidney function and albuminuria (all P-interactions >0.50). Reductions were driven by hospitalizations due to infection, cardiac, renal or urinary, and metabolism or nutritional disorders. We estimated that SGLT2 inhibition in CKD would prevent 36 (95% CI 13-56) unplanned hospitalizations per 1000 patient-years of treatment, across a broad range of patients. Conclusions: SGLT2 inhibitors reduce the risk of hospitalizations from any cause in patients with CKD, irrespective of diabetes status, kidney function and degree of albuminuria.

Background: Complications relating to delayed or deteriorating graft function following kidney transplantation are common. There is no validated method apart from transplant kidney biopsy which can accurately identify between the histopathological causes of graft dysfunction. Considering an unmet critical need for a non-invasive approach to reliably diagnose kidney transplant complications, this work proposes a novel methodology based on the assessment of exfoliated proximal tubule cells (PTCs) extracted from urine of kidney transplant recipients by using their multispectral autofluorescence features. Methods: Three groups of 10 patients who have undergone clinically indicated transplant kidney biopsy and was subsequently diagnosed with either acute tubular necrosis (ATN), graft rejection or non-rejection associated interstitial fibrosis and tubular atrophy (IFTA) took part in this study. Exfoliated PTCs from urine collected prior to transplant biopsy were extracted using a validated immunomagnetic separation method based on anti-CD13 and anti-SGLT2 antibodies. Imaging was performed on a custom-made multispectral autofluorescence microscopy and camera system. Multispectral autofluorescence images of PTCs were quantitatively analysed by using optimised small sets of features to prevent overfitting. Binary classification was carried out by a random forest classifier, and the AutoGluon machine learning software. Results were validated by 5-fold cross validation. Results: For random forest classification, features were selected using entropy-based feature selection, resulting in AUC values of 0.92 (ATN versus graft rejection), 0.86 (ATN versus IFTA) and 0.62 (graft rejection versus IFTA) respectively. The AutoGluon classifier optimisation for the same features resulted in AUC values of 0.95 (ATN versus graft rejection), 0.92 (ATN versus IFTA) and 0.91 (graft rejection vs IFTA). Conclusions: Our results demonstrate a proof-of-concept that measurement of autofluorescent features from urinary exfoliated PTCs multispectral autofluorescence could differentiate between patient groups with ATN, graft rejection and IFTA in kidney transplant recipients to an excellent degree of accuracy using AutoGluon classifier optimisation.

Kidney fibrosis is the common pathological pathway in progressive chronic kidney disease (CKD), and current treatments are largely ineffective. The C-X-C chemokine receptor 4 (CXCR4) is crucial to fibrosis development. By using neural cell adhesion molecules as scaffolds with binding loops that mimic the shape of shark antibodies, fully humanized single-domain i-bodies have been developed. The first-generation i-body, AD-114, demonstrated antifibrotic effects in a mouse model of folic acid (FA)-induced renal fibrosis. The second-generation i-body, AD-214, is an Fc-fusion protein with an extended half-life, enhanced activity, and a mutated Fc domain to prevent immune activation. To investigate the renoprotective mechanisms of AD-214, RPTEC/TERT1 cells (a human proximal tubular cell line) were incubated with TGF-b1 with/without AD-214 and the supernatant was collected to measure collagen levels by Western blot. Mice with unilateral ureteral obstruction (UUO) received AD-214 intraperitoneally (i.p.) every two days for 14 days. Kidney fibrosis markers and kidney function were then analyzed. AD-214 suppressed TGF-b1-induced collagen overexpression in RPTEC/TERT1 cells. In UUO mice, AD-214 reduced extracellular matrix (ECM) deposition, restored kidney function, and limited leukocyte infiltration. In a scratch assay, AD-214 also inhibited macrophage migration. To conclude, i-body AD-214 attenuates UUO-induced kidney fibrosis by inhibiting leukocyte infiltration and macrophage migration.