The early natural history of nephropathy in type 1 diabetes: I. Study design and baseline characteristics of the study participants

Kidney biopsy findings in children with diabetes mellitus

BACKGROUND

Diabetic nephropathy may begin in childhood, but clinical kidney disease ascribable to this is uncommon in children with type 1 (insulin dependent) diabetes mellitus.

METHODS

We reviewed our experience of kidney biopsies in children with type 1 diabetes mellitus.

RESULTS

Between 1995 and 2022, there were biopsies in 17 children, with various clinical indications for kidney biopsy, making this the largest series of biopsies in diabetic children with clinical kidney abnormalities. Four biopsies showed diabetic nephropathy, three showed the combination of diabetic nephropathy and IgA nephropathy, and ten showed a variety of conditions other than diabetic nephropathy: minimal change disease (2), membranous nephropathy (2), thin glomerular basement membrane lesion (2), non-glomerular chronic damage in Wolcott-Rallison syndrome (2), acute pauciimmune necrotizing crescentic glomerulonephritis (1) and IgA nephropathy (1). Clinical clues of something other than diabetic nephropathy included acute kidney injury, microscopic haematuria or chronic kidney impairment with little or no proteinuria and the nephrotic syndrome after a short duration of diabetes.

CONCLUSIONS

We confirm that changes better known in adults with either type 1 or type 2 diabetes mellitus can occur in children with type 1 diabetes mellitus: overt diabetic nephropathy either on its own or combined with other conditions and kidney disorders other than diabetic nephropathy.

Associations of Biomarkers of Tubular Injury and Inflammation with Biopsy Features in Type 1 Diabetes

BACKGROUND

Whether biomarkers of tubular injury and inflammation indicate subclinical structural kidney pathology early in type 1 diabetes remains unknown.

METHODS

We investigated associations of biomarkers of tubular injury and inflammation with kidney structural features in 244 adults with type 1 diabetes from the Renin-Angiotensin System Study, a randomized, placebo-controlled trial testing effects of enalapril or losartan on changes in glomerular, tubulointerstitial, and vascular parameters from baseline to 5-year kidney biopsies. Biosamples at biopsy were assessed for kidney injury molecule 1 (KIM-1), soluble TNF receptor 1 (sTNFR1), arginine-to-citrulline ratio in plasma, and uromodulin and epidermal growth factor (EGF) in urine. We examined cross-sectional correlations between biomarkers and biopsy features and baseline biomarker associations with 5-year changes in biopsy features.

RESULTS

Participants' mean age was 30 years (SD 10) and diabetes duration 11 years (SD 5); 53% were women. The mean GFR measured by iohexol disappearance was 128 ml/min per 1.73 m 2 (SD 19) and median urinary albumin excretion was 5 μ g/min (interquartile range, 3-8). KIM-1 was associated with most biopsy features: higher mesangial fractional volume (0.5% [95% confidence interval (CI), 0.1 to 0.9] greater per SD KIM-1), glomerular basement membrane (GBM) width (14.2 nm [95% CI, 6.5 to 22.0] thicker), cortical interstitial fractional volume (1.1% [95% CI, 0.6 to 1.6] greater), fractional volume of cortical atrophic tubules (0.6% [95% CI, 0.2 to 0.9] greater), and arteriolar hyalinosis index (0.03 [95% CI, 0.1 to 0.05] higher). sTNFR1 was associated with higher mesangial fractional volume (0.9% [95% CI, 0.5 to 1.3] greater) and GBM width (12.5 nm [95% CI, 4.5 to 20.5] thicker) and lower GBM surface density (0.003 μ m 2 / μ m 3 [95% CI, 0.005 to 0.001] lesser). EGF and arginine-to-citrulline ratio correlated with severity of glomerular and tubulointerstitial features. Baseline sTNFR1, uromodulin, and EGF concentrations were associated with 5-year glomerular and tubulointerstitial feature progression.

CONCLUSIONS

Biomarkers of tubular injury and inflammation were associated with kidney structural parameters in early type 1 diabetes and may be indicators of kidney disease risk.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Renin Angiotensin System Study (RASS/B-RASS), NCT00143949.

PODCAST

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Relationship between biomarkers of tubular injury and intrarenal hemodynamic dysfunction in youth with type 1 diabetes

BACKGROUND

Early identification of youth with type 1 diabetes (T1D) at risk for diabetic kidney disease may improve clinical outcomes. We examined the cross-sectional relationship between kidney biomarkers neutrophil gelatinase-associated lipocalin (NGAL), copeptin, interleukin-18 (IL-18), kidney injury molecule-1 (KIM-1), chitinase-3-like protein-1 (YKL-40), and monocyte chemoattractant protein-1 (MCP-1) and intrarenal hemodynamic function in adolescents with T1D.

METHODS

Urine albumin-to-creatinine ratio (UACR), renal vascular resistance (RVR), glomerular filtration rate (GFR), intraglomerular pressure (PGLO), efferent arteriole resistance (RE), afferent arteriolar resistance (RA), and renal plasma flow (RPF), and the above indicated biomarkers were assessed in youth aged 12-21 years with and without T1D of < 10 years duration.

RESULTS

Fifty adolescents with T1D (16.1 ± 3.0 years, HbA1c 8.6 ± 1.2%) and 20 adolescents of comparable BMI without T1D (16.1 ± 2.9 years, HbA1c 5.2 ± 0.2%) were enrolled. Adolescents with T1D demonstrated significantly higher GFR, RPF, RE, and PGLO than controls (39%, 33%, 74%, and 29%, respectively, all p < 0.0001). Adolescents with T1D also exhibited significantly lower RVR and RA than controls (25% and 155%, respectively, both p < 0.0001). YKL-40 and KIM-1 concentrations, respectively, were positively associated with GFR (r: 0.43, p = 0.002; r: 0.41, p = 0.003), RPF (r: 0.29, p = 0.08; r: 0.34, p = 0.04), UACR (r: 0.33, p = 0.02; r: 0.50, p = 0.0002), and PGLO (r: 0.45, p = 0.006; r: 0.52, p = 0.001) in adolescents with T1D.

CONCLUSIONS

Higher concentrations of biomarkers YKL-40 and KIM-1 may help define the risk for intraglomerular hemodynamic dysfunction in youth with T1D. A higher resolution version of the Graphical abstract is available as Supplementary information.

Trimetazidine an emerging paradigm in renal therapeutics: Preclinical and clinical insights

Trimetazidine (TMZ) is a well-known anti-ischemic agent used for the treatment of angina pectoris. In the past decades, the efficacy of this drug has been tested in a wide range of kidney injuries, including drug-induced nephrotoxicity (DIN), radio-contrast agent-induced nephropathy, and surgically induced renal ischemic injury. TMZhas renoprotective effects by attenuating oxidative stress, inflammatory cytokine release, maintaining oxygen and energy balance. Moreover, TMZ administration prevented kidney graft rejection in the porcine model by suppressing the infiltration of mononuclear cells, preserving mitochondrial functions, and maintaining Ca+ homeostasis. In DIN and diabetic kidney diseases,TMZ treatment prevents renal injury by inactivating immune cells, attenuating renal fibrosis, inflammation, apoptosis, and histological abnormalities. Interestingly, the clinical therapeutic efficacy of TMZ has also been documented in pre-existing kidney disease patients undergoing contrast exposure for diagnostic intervention. However, the mechanistic insights into the TMZ mediated renoprotective effects in other forms of renal injuries, including type-2 diabetes, drug-induced nephrotoxicity, and hypertension-induced chronic kidney diseases, remain uninvestigated and incomplete. Moreover, the clinical utility of TMZ as a renoprotective agent in radio-contrast-induced nephrotoxicity needs to be tested in a large patient population. Nevertheless, the available pieces of evidence suggest that TMZ is a promising and emerging renal therapy for the treatment and management of kidney diseases of variable etiologies. This review discusses the various pre-clinical and clinical findings and provides mechanistic insights into the TMZ mediated beneficial effects in various kidney diseases.

Combining glomerular basement membrane and tubular basement membrane assessment improves the prediction of diabetic end-stage renal disease

BACKGROUND

To address the prognostic value of combining tubular basement membrane (TBM) and glomerular basement membrane (GBM) thickness in diabetic nephropathy (DN).

METHODS

This retrospective study enrolled 110 patients with type 2 diabetes and biopsy-proven DN from 2011 to 2018. The pathological findings were confirmed according to the Renal Pathology Society classifications. GBM and TBM thicknesses were determined using the Haas' direct measurement/arithmetic mean method and orthogonal intercept method, respectively. Cox proportional hazard models were used to investigate the hazard ratios (HRs) for the influence of combined GBM and TBM thickness for predicting end-stage renal disease (ESRD).

RESULTS

Patients were assigned to three groups according to the median GBM and TBM thickness: GBM^lo TBM^lo (GBM < 681 nm and TBM < 1200 nm), GBM^hi TBM^lo /GBM^lo TBM^hi (GBM ≥ 681 nm and TBM < 1200 nm, or GBM < 681 nm and TBM ≥ 1200 nm), and GBM^hi TBM^hi (GBM ≥ 681 nm and TBM ≥ 1200 nm). The GBM^hi TBM^lo /GBM^lo TBM^hi and GBM^hi TBM^hi groups displayed poorer renal function, a more severe glomerular classification and interstitial inflammation, and poorer renal survival rates than the GBM^lo TBM^lo group The GBM^hi TBM^lo /GBM^lo TBM^hi and GBM^hi TBM^hi groups had adjusted HRs of 1.49 (95% confidence interval [CI], 1.21-9.75) and 3.07 (95% CI, 2.87-12.78), respectively, compared with the GBM^lo TBM^lo group.

CONCLUSIONS

TBM thickness enhanced GBM thickness for renal prognosis in patients with type 2 diabetes.

Urinary Extracellular Vesicles as a Source of NGAL for Diabetic Kidney Disease Evaluation in Children and Adolescents With Type 1 Diabetes Mellitus

BACKGROUND

Tubular damage has a role in Diabetic Kidney Disease (DKD). We evaluated the early tubulointerstitial damage biomarkers in type-1 Diabetes Mellitus (T1DM) pediatric participants and studied the correlation with classical DKD parameters.

METHODS

Thirty-four T1DM and fifteen healthy participants were enrolled. Clinical and biochemical parameters [Glomerular filtration Rate (GFR), microalbuminuria (MAU), albumin/creatinine ratio (ACR), and glycated hemoglobin A1c (HbA1c)] were evaluated. Neutrophil gelatinase-associated lipocalin (NGAL), Hypoxia-inducible Factor-1α (HIF-1α), and Nuclear Factor of Activated T-cells-5 (NFAT5) levels were studied in the supernatant (S) and the exosome-like extracellular vesicles (E) fraction from urine samples.

RESULTS

In the T1DM, 12% had MAU >20 mg/L, 6% ACR >30 mg/g, and 88% had eGFR >140 ml/min/1.72 m². NGAL in the S (NGAL-S) or E (NGAL-E) fraction was not detectable in the control. The NGAL-E was more frequent (p = 0.040) and higher (p = 0.002) than NGAL-S in T1DM. The T1DM participants with positive NGAL had higher age (p = 0.03), T1DM evolution (p = 0.03), and serum creatinine (p = 0.003) than negative NGAL. The NGAL-E correlated positively with tanner stage (p = 0.0036), the median levels of HbA1c before enrollment (p = 0.045) and was independent of ACR, MAU, and HbA1c at the enrollment. NFAT5 and HIF-1α levels were not detectable in T1DM or control.

CONCLUSION

Urinary exosome-like extracellular vesicles could be a new source of early detection of tubular injury biomarkers of DKD in T1DM patients.

Diabetic Kidney Disease: Challenges, Advances, and Opportunities

BACKGROUND

Diabetic kidney disease (DKD) is the most common cause of the end-stage renal disease (ESRD). Regardless of intensive treatments with hyperglycemic control, blood pressure control, and the use of renin-angiotensin system blockades, the prevalence of DKD remains high. Recent studies suggest that the spectrum of DKD has been changed and many progresses have been made to develop new treatments for DKD. Therefore, it is time to perform a systemic review on the new developments in the field of DKD.

SUMMARY

Although the classic clinical presentation of DKD is characterized by a slow progression from microalbuminuria to macroalbuminuria and by a hyperfiltration at the early stage and progressive decline of renal function at the late stage, recent epidemiological studies suggest that DKD patients have a variety of clinical presentations and progression rates to ESRD. Some DKD patients have a decline in renal function without albuminuria but display prominent vascular and interstitial fibrosis on renal histology. DKD patients are more susceptible to acute kidney injury, which might contribute to the interstitial fibrosis. A large portion of type 2 diabetic patients with albuminuria could have overlapping nondiabetic glomerular disease, and therefore, kidney biopsy is required for differential diagnosis for these patients. Only a small portion of DKD patients eventually progress to end-stage renal failure. However, we do not have sensitive and specific biomarkers to identify these high-risk patients. Genetic factors that have a strong association with DKD progression have not been identified yet. A combination of circulating tumor necrosis factor receptor (TNFR)1, TNFR2, and kidney injury molecular 1 provides predictive value for DKD progression. Artificial intelligence could enhance the predictive values for DKD progression by combining the clinical parameters and biological markers. Sodium-glucose co-transporter-2 inhibitors should be added to the new standard care of DKD patients. Several promising new drugs are in clinical trials.

KEY MESSAGES

Over last years, our understanding of DKD has been much improved and new treatments to halt the progression of DKD are coming. However, better diagnostic tools, predictive markers, and treatment options are still urgently needed to help us to better manage these patients with this detrimental disease.

Comparison of urinary amino acid excretory pattern in patients with type 2 diabetes mellitus and non-diabetic healthy controls at a tertiary referral hospital in India

AIM

Specific amino acids have been linked to regulation of insulin secretion from pancreatic β-cells; on the contrary, increased concentration of certain amino acids is associated with insulin resistance (IR) and development of type 2 diabetes mellitus (T2DM). Nowadays, urine as a biological sample has attracted more attention for diagnosis of disease for its special superiority; insufficient research in the study of urinary amino acid (UAA) pattern in patients with T2DM has led to the present study with the aim to determine the levels of UAAs, their excretory patterns and the association of UAA to plasma glucose and IR in patients with T2DM.

METHODS

Quantification of total urinary amino acids was done spectrophotometrically and the patterns of amino acid excretion was elucidated by thin layer chromatography technique. Fasting blood samples were used for plasma glucose and insulin estimation by fully automated analyzer.

RESULT

The levels of UAA in patients with T2DM in comparison to healthy controls were higher (p < 0.0001). The frequency of urinary phenylalanine, arginine, tryptophan, tyrosine and cysteine were significantly higher in patients with T2DM than controls. There was also a strong positive correlation of UAA levels with blood glucose levels and HOMA-IR in patients with T2DM.

CONCLUSION

Our study has shown subtle abnormalities in UAA patterns in patients with T2DM. The measurement of UAA levels and excretory pattern can be used as an index of hyperglycemia and IR which could serve as an inexpensive and non-invasive marker for T2DM. More studies are required to confirm this association.

Serial renal biopsies in normo- and microalbuminuric patients with type 2 diabetes demonstrate that loss of renal function is associated with a reduction in glomerular filtration surface secondary to mesangial expansion

AIMS

The aim of the present study was to explore the relationship between changes in renal structure in patients with type 2 diabetes at an early stage of diabetic nephropathy using serial renal biopsies, and change in renal function.

METHODS

The study population comprised 10 patients with type 2 diabetes with normo- or microalbuminuria at baseline. Light and electron microscopy-based morphometric analyses were performed to quantitatively evaluate glomerular and interstitial structural changes. Urinary albumin excretion (UAE) and glomerular filtration rate (GFR) were measured annually. A second renal biopsy was performed after a mean of 6.1 ± 2.4 years of follow-up.

RESULTS

UAE, GFR, blood pressure and severity of diabetic retinopathy (DR) did not change between the baseline and follow-up. The annual decrease in the surface density of the peripheral glomerular basement membrane (GBM) (Sv[PGBM/glom]) was correlated with the rate of loss of GFR during the six-year follow-up period. The annual change in the Sv(PGBM/glom) was negatively correlated with the change in mesangial volume fraction.

CONCLUSIONS

Decreases in the GFR in patients with type 2 diabetes with normo- or microalbuminuria at baseline were associated with a decreased glomerular filtration surface, as a result of mesangial expansion during a mean six years of observation. These findings confirm ongoing pathological progression of glomerulopathy despite no significant change in albuminuria or retinopathy status.

ANGPTL4: A Predictive Marker for Diabetic Nephropathy

BACKGROUND

ANGPTL4 is a glycoprotein that is involved in regulating triglyceride metabolism by inhibiting LPL activity under fasting conditions. Additionally, ANGPTL4 has been suggested as a link between hypertriglyceridemia and albuminuria in the nephrotic syndrome. In this study, we examined levels of circulating ANGPTL4 in people with diabetic nephropathy (DN) and its association with established DN-associated proteins such as IGFBP1 and IGFBP4.

METHODS

We quantified circulating ANGPTL4, IGFBP1, IGFBP3, and IGFBP4 in fasting plasma samples of 122 Kuwaiti participants using a multiplexing assay. The study involved 36 controls, as well as 86 people with type 2 diabetes (T2D) including 37 people with normal kidney function and 49 people with DN.

RESULTS

ANGPTL4 level was increased in people with DN (241.56 ± 14.1 μg/ml) compared to the control group (178.43 ± 24.09 μg/ml). The increase in ANGPTL4 correlated with clinical parameters of DN including albumin-to-creatinine ratio (r = 0.271, P = 0.002), serum creatinine (r = 0.381, P = 0.0001), and eGFR (r = -0.349, P < 0.0001). Furthermore, ANGPTL4 correlated positively with both IGFBP1 (r = 0.202, P = 0.026) and IGFBP4 (r = 0.364, P < 0.0001). Multiple regression analysis showed increased IGFBP1 and TG as predictors of higher ANGPTL4 in people with DN. In people with T2D, only IGFBP1 acted as a positive predictor of a rise in ANGPTL4.

CONCLUSION

In this study, our data showed a significant increase in circulating ANGPTL4, IGFBP1, and IGFBP4 in patients with DN. The elevation in ANGPTL4 correlated significantly with clinical markers of DN such as ACR, serum creatinine, and eGFR, as well as IGFBP1 and IGFBP4. Altogether, this suggests a potential role for ANGPTL4 in DN perhaps through its role in inhibiting LPL activity and promotes ANGPTL4 as a biochemical marker for the detection of a diabetic kidney disease in patients with T2D.

Urine inositol pentakisphosphate 2-kinase and changes in kidney structure in early diabetic kidney disease in type 1 diabetes

We examined the association of urine inositol 1,3,4,5,6-pentakisphosphate 2-kinase (IPP2K) with the presence and progression of diabetic kidney disease (DKD) lesions. Urine IPP2K was measured at baseline by quantitative liquid chromatography-mass spectrometry in 215 participants from the Renin-Angiotensin System Study who had type 1 diabetes and were normoalbuminuric and normotensive with normal or increased glomerular filtration rate (GFR). Urine IPP2K was detectable in 166 participants. Participants with IPP2K below the limit of quantification (LOQ) were assigned concentrations of LOQ/√2. All concentrations were then standardized to urine creatinine (Cr) concentration. Kidney morphometric data were available from biopsies at baseline and after 5 yr. Relationships of IPP2K/Cr with morphometric variables were assessed by linear regression after adjustment for age, sex, diabetes duration, hemoglobin A_1c, mean arterial pressure, treatment assignment, and, for longitudinal analyses, baseline structure. Baseline mean age was 29.7 yr, mean diabetes duration 11.2 yr, median albumin excretion rate 5.0 μg/min, and mean iohexol GFR 129 ml·min^-1·1.73m^-2. Higher IPP2K/Cr was associated with higher baseline peripheral glomerular total filtration surface density [Sv(PGBM/glom), tertile 3 vs. tertile 1 β = 0.527, P = 0.011] and with greater preservation of Sv(PGBM/glom) after 5 yr ( tertile 3 vs. tertile 1 β = 0.317, P = 0.013). Smaller increases in mesangial fractional volume ( tertile 3 vs. tertile 1 β = -0.578, P = 0.018) were observed after 5 yr in men with higher urine IPP2K/Cr concentrations. Higher urine IPP2K/Cr is associated with less severe kidney lesions at baseline and with preservation of kidney structure over 5 yr in individuals with type 1 diabetes and no clinical evidence of DKD at baseline.

Mitochondrial Reactive Oxygen Species and Kidney Hypoxia in the Development of Diabetic Nephropathy

The underlying mechanisms in the development of diabetic nephropathy are currently unclear and likely consist of a series of dynamic events from the early to late stages of the disease. Diabetic nephropathy is currently without curative treatments and it is acknowledged that even the earliest clinical manifestation of nephropathy is preceded by an established morphological renal injury that is in turn preceded by functional and metabolic alterations. An early manifestation of the diabetic kidney is the development of kidney hypoxia that has been acknowledged as a common pathway to nephropathy. There have been reports of altered mitochondrial function in the diabetic kidney such as altered mitophagy, mitochondrial dynamics, uncoupling, and cellular signaling through hypoxia inducible factors and AMP-kinase. These factors are also likely to be intertwined in a complex manner. In this review, we discuss how these pathways are connected to mitochondrial production of reactive oxygen species (ROS) and how they may relate to the development of kidney hypoxia in diabetic nephropathy. From available literature, it is evident that early correction and/or prevention of mitochondrial dysfunction may be pivotal in the prevention and treatment of diabetic nephropathy.

Interleukin-20 targets podocytes and is upregulated in experimental murine diabetic nephropathy

Interleukin (IL)-20, a proinflammatory cytokine of the IL-10 family, is involved in acute and chronic renal failure. The aim of this study was to elucidate the role of IL-20 during diabetic nephropathy development. We found that IL-20 and its receptor IL-20R1 were upregulated in the kidneys of mice and rats with STZ-induced diabetes. In vitro, IL-20 induced MMP-9, MCP-1, TGF-β1 and VEGF expression in podocytes. IL-20 was upregulated by hydrogen peroxide, high-dose glucose and TGF-β1. In addition, IL-20 induced apoptosis in podocytes by activating caspase-8. In STZ-induced early diabetic nephropathy, IL-20R1-deficient mice had lower blood glucose and serum BUN levels and a smaller glomerular area than did wild-type controls. Anti-IL-20 monoclonal antibody (7E) treatment reduced blood glucose and the glomerular area and improved renal functions in mice in the early stage of STZ-induced diabetic nephropathy. ELISA showed that the serum IL-20 level was higher in patients with diabetes mellitus than in healthy controls. The findings of this study suggest that IL-20 induces cell apoptosis of podocytes and plays a role in the pathogenesis of early diabetic nephropathy.

Circulating fibronectin contributes to mesangial expansion in a murine model of type 1 diabetes

Fibronectin is ubiquitously expressed in the extracellular matrix, and its accumulation in the glomerular mesangium in diabetic nephropathy is associated with deterioration of renal function in these patients. However, the exact role of fibronectin in the pathogenesis of diabetic nephropathy remains unknown. To clarify this, we administered fluorescent-labeled plasma fibronectin to wild-type mice and found it to accumulate in the mesangium. Using liver-specific conditional-knockout mice to decrease circulating fibronectin, we reduced circulating fibronectin by more than 90%. In streptozotocin-induced diabetes of these knockout mice, the pronounced fall in circulating fibronectin resulted in a decrease in mesangial expansion by 25% and a decline in albuminuria by 30% compared to diabetic control mice. Indeed, the amount of fibronectin in the kidney was reduced, as was the total amount of collagen. In vitro experiments confirmed that matrix accumulation of fibronectin was enhanced by increasing fibronectin only, glucose only, or the combination of both. Thus, circulating fibronectin contributes to mesangial expansion and exacerbation of albuminuria in a murine model of type 1 diabetes.

RAS and sex differences in diabetic nephropathy

The incidence and progression of kidney diseases are influenced by sex. The renin-angiotensin system (RAS) is an important regulator of cardiovascular and renal function. Sex differences in the renal response to RAS blockade have been demonstrated. Circulating and renal RAS has been shown to be altered in type 1 and type 2 diabetes; this enzymatic cascade plays a critical role in the development of diabetic nephropathy (DN). Angiotensin converting enzyme (ACE) and ACE2 are differentially regulated depending on its localization within the diabetic kidney. Furthermore, clinical and experimental studies have shown that circulating levels of sex hormones are clearly modulated in the context of diabetes, suggesting that sex-dependent RAS regulation may be also be affected in these individuals. The effect of sex hormones on circulating and renal RAS may be involved in the sex differences observed in DN progression. In this paper we will review the influence of sex hormones on RAS expression and its relation to diabetic kidney disease. A better understanding of the sex dimorphism on RAS might provide a new approach for diabetic kidney disease treatment.

Age at menarche and the risk of diabetic microvascular complications in patients with type 1 diabetes

AIMS/HYPOTHESIS

The aim of this study was to evaluate the relationship among age at onset of diabetes, age at onset of menarche and risk of diabetic nephropathy and laser-treated retinopathy in type 1 diabetes.

METHODS

Data related to age at menarche were collected through questionnaires and were available for 1,304 women who participated in the Finnish Diabetic Nephropathy Study (FinnDiane). A possible association between age at menarche and diabetic nephropathy and retinopathy was investigated.

RESULTS

There was an inverse relationship between the age at onset of diabetes and age at menarche: the younger the age at onset of diabetes, the higher the age at menarche (p < 0.0001). A non-linear relationship between the age of menarche and risk of diabetic microvascular complications was found in patients with diabetes onset before menarche, but there was no such association in patients with diabetes onset after menarche. Women with delayed menarche (> mean age + 2 years) had a 2.30 (95% CI 1.27, 4.17; p < 0.006) times higher risk of nephropathy compared with the women who underwent menarche at the mean age ± 2 years. Delayed menarche also increased the risk of retinopathy (OR 2.34 [95% CI 1.36, 4.01]). After excluding patients with nephropathy, the OR for retinopathy was 2.11 (95% CI 1.15, 3.90). Earlier menarche (< mean age - 2 years) did not have any effect on this risk.

CONCLUSIONS/INTERPRETATION

Delayed menarche was associated with an increased risk of diabetic nephropathy and retinopathy, whereas early menarche was not. Delayed menarche may be used as a new tool to identify women at risk of diabetic microvascular complications.

Diabetic Kidney Disease in Adolescents With Type 2 Diabetes: New Insights and Potential Therapies

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease (ESRD) and dialysis in the Western world. Early DKD, including microalbuminuria and renal hyperfiltration, is common in adolescents with type 2 diabetes (T2D). Furthermore, youth-onset T2D carries a higher risk of progressive DKD than adult-onset T2D of similar diabetes duration. DKD is characterized by a long clinically silent period without signs of disease. Therefore, a major challenge in preventing DKD is the difficulty in identifying high-risk T2D patients at an early stage. The Type 2 Diabetes in Adolescents and Youth (TODAY) study demonstrated a high initial prevalence that increased over time, irrespective of treatment arm. This key observation underscores the importance of discovering new therapeutic targets to supplement conventional management, in order to reduce DKD risk. In this review, we focus on early DKD in T2D and summarize potential novel biomarkers and therapeutic targets.

Aryl Hydrocarbon Receptor Deficiency Attenuates Oxidative Stress-Related Mesangial Cell Activation and Macrophage Infiltration and Extracellular Matrix Accumulation in Diabetic Nephropathy

AIMS

Activation of glomerular mesangial cells (MCs) and functional changes of renal tubular cells are due to metabolic abnormalities, oxidative stress, and matrix accumulation in the diabetic nephropathy (DN). Aryl hydrocarbon receptor (AhR) activation has been implicated in DN. In this study, we investigated the role of AhR in the pathophysiological processes of DN using AhR knockout (AhRKO) and pharmacological inhibitor α-naphthoflavone mouse models.

RESULTS

The increased blood glucose, glucose intolerance, MC activation, macrophage infiltration, and extracellular matrix (ECM) accumulation were significantly attenuated in AhRKO mice with diabetic inducer streptozotocin (STZ) treatment. AhR deficiency by genetic knockout or pharmacological inhibition also decreased the induction of cyclooxygenase-2 (COX-2)/prostaglandin E₂ (PGE₂), lipid peroxidation, oxidative stress, NADPH oxidase activity, and N-ɛ-carboxymethyllysine (CML, a major advanced glycation end product) in STZ-induced diabetic mice. CML showed remarkably increased AhR/COX-2 DNA-binding activity, protein-DNA interactions, gene regulation, and ECM formation in MCs and renal proximal tubular cells, which could be reversed by siRNA-AhR transfection. CML-increased AhR nuclear translocation and biological activity in MCs and renal proximal tubular cells could also be effectively attenuated by antioxidants.

INNOVATION

We elucidate for the first time that AhR plays an important role in MC activation, macrophage infiltration, and ECM accumulation in DN conferred by oxidative stress.

CONCLUSIONS

AhR-regulated COX-2/PGE₂ expression and ECM deposition through oxidative stress cascade is involved in the CML-triggered MC activation and macrophage infiltration. These findings suggest new insights into the development of therapeutic approaches to reduce diabetic microvascular complications. Antioxid. Redox Signal. 24, 217-231.

Tumor necrosis factor receptors 1 and 2 are associated with early glomerular lesions in type 2 diabetes

Elevated serum tumor necrosis factor receptor 1 (TNFR1) and 2 (TNFR2) concentrations are strongly associated with increased risk of end-stage renal disease in type 2 diabetes. However, little is known about the early glomerular structural lesions that develop in patients when these markers are elevated. Here we examined the relationships between TNFRs and glomerular structure in 83 American Indians with type 2 diabetes. Serum TNFRs and glomerular filtration rates (GFR, iothalamate) were measured during a research exam performed within a median of 0.9 months from a percutaneous kidney biopsy. Associations of TNFRs with glomerular structural variables were quantified by Spearman's correlations and by multivariable linear regression after adjustment for age, gender, diabetes duration, hemoglobin A1c, body mass index, and mean arterial pressure. The baseline mean age was 46 years, median GFR 130 ml/min, median albumin/creatinine ratio 26 mg/g, median TNFR1 1500 pg/ml, and median TNFR2 3284 pg/ml. After multivariable adjustment, TNFR1 and TNFR2 significantly correlated inversely with the percentage of endothelial cell fenestration and the total filtration surface per glomerulus. There were significant positive correlations with mesangial fractional volume glomerular basement membrane width, podocyte foot process width, and percent of global glomerular sclerosis. Thus, TNFRs may be involved in the pathogenesis of early glomerular lesions in diabetic nephropathy.

Mechanisms of bradykinin-induced expression of connective tissue growth factor and nephrin in podocytes

Diabetic nephropathy (DN) is the main cause of morbidity and mortality in diabetes and is characterized by mesangial matrix deposition and podocytopathy, including podocyte loss. The risk factors and mechanisms involved in the pathogenesis of DN are still not completely defined. In the present study, we aimed to understand the cellular mechanisms through which activation of B2 kinin receptors contribute to the initiation and progression of DN. Stimulation of cultured rat podocytes with bradykinin (BK) resulted in a significant increase in ROS generation, and this was associated with a significant increase in NADPH oxidase (NOX)1 and NOX4 protein and mRNA levels. BK stimulation also resulted in a signicant increase in the phosphorylation of ERK1/2 and Akt, and this effect was inhibited in the presence of NOX1 and Nox4 small interfering (si)RNA. Furthermore, podocytes stimulated with BK resulted in a significant increase in protein and mRNA levels of connective tissue growth factor (CTGF) and, at the same time, a significant decrease in protein and mRNA levels of nephrin. siRNA targeted against NOX1 and NOX4 significantly inhibited the BK-induced increase in CTGF. Nephrin expression was increased in response to BK in the presence of NOX1 and NOX4 siRNA, thus implicating a role for NOXs in modulating the BK response in podocytes. Moreover, nephrin expression in response to BK was also significantly increased in the presence of siRNA targeted against CTGF. These findings provide novel aspects of BK signal transduction pathways in pathogenesis of DN and identify novel targets for interventional strategies.

Long-term Outcomes in Youths with Diabetes Mellitus

In this article, the author reviews the long-term outcomes and their precursors of type 1 diabetes starting in youth. The author also contrasts the changing incidence of these long-term complications as we have moved from the pre-Diabetes Control and Complications Trial (DCCT) to the post-DCCT standard of care and reviews the emerging data related to complications in youths with type 2 diabetes. Finally, the author reviews the recent understanding related to the effects of diabetes on the brain and cognition.

Podocyte structural parameters do not predict progression to diabetic nephropathy in normoalbuminuric type 1 diabetic patients

BACKGROUND

Podocyte injury has been implicated in diabetic nephropathy (DN) ranging from normoalbuminuria to proteinuria in both type 1 and type 2 diabetes.

METHODS

To determine whether podocyte structural parameters predict DN risk in initially normoalbuminuric long-standing type 1 diabetic patients, we performed a nested case-control study in sex and diabetes duration-matched progressors (progression to proteinuria or ESRD, n = 10), non-progressors (normoalbuminuric at follow-up, n = 10), and non-diabetic controls (n = 10).

RESULTS

HbA1c and diastolic blood pressure were higher in progressors versus non-progressors. Podocyte number per glomerulus, numerical density of podocyte per glomerulus, and foot process width were not different among groups. The glomerular basement membrane width was greater in progressors versus non-progressors or controls, and in non-progressors versus controls. As expected, the mesangial fractional volume was greater in progressors and non-progressors versus controls, with no differences between progressors and non-progressors.

CONCLUSION

This study does not indicate that podocyte structural changes are preconditions for later DN progression in initially normoalbuminuric type 1 diabetic patients. However, this does not preclude an important role for podocyte injury at a later stage of DN.

Diabetes Complications in Childhood Diabetes-New Biomarkers and Technologies

A major challenge in preventing vascular complications in diabetes is the inability to identify high-risk patients at an early stage, emphasizing the importance of discovering new risk factors, technologies and therapeutic targets to reduce the development and progression of complications. Promising biomarkers which may improve risk stratification and serve as therapeutic targets, include: uric acid, insulin sensitivity, copeptin, SGLT-2 and Klotho/FGF-23. Non-invasive measures of macrovasuclar disease in youth, include: 1) pulse wave velocity to examine arterial stiffness; 2) carotid intima-media thickness to evaluate arterial thickness; 3) cardiac MRI to investigate cardiac function and structure. Novel microvascular measures include: GFR by iohexol clearance using filter paper to directly measure GFR, retinal vascular geometry to predict early retinal changes and corneal confocal microscopy to improve detection of early nerve loss to better predict diabetic neuropathy. Herein we will review technologies, novel biomarkers, and therapeutic targets in relation to vascular complications of diabetes.

Achieving International Society for Pediatric and Adolescent Diabetes and American Diabetes Association clinical guidelines offers cardiorenal protection for youth with type 1 diabetes

OBJECTIVE

Most youth with type 1 diabetes do not meet the American Diabetes Association (ADA) and International Society for Pediatric and Adolescent Diabetes (ISPAD) targets for hemoglobin A1c (HbA1c), blood pressure (BP), lipids, and body mass index (BMI). We hypothesized that ISPAD/ADA goal achievement at baseline would be associated with cardiorenal risk factors at baseline and 2 yr follow-up in adolescents with type 1 diabetes.

METHODS

We assessed the cross-sectional and longitudinal relationships between ISPAD/ADA goal achievement at baseline and cardiorenal health at baseline and 2-yr follow-up (n = 297; 15.4 ± 2.1 yr at baseline) in adolescents with type 1 diabetes. Goal achievement was defined as HbA1c < 7.5%, BP < 90th percentile for age, sex, and height, low density lipoprotein-cholesterol (LDL-C) <100 mg/dL, high density lipoprotein-cholesterol (HDL-C) >35 mg/dL, triglycerides (TG) <150 mg/dL and BMI <85th percentile for age and sex. Cardiorenal outcomes included pulse-wave velocity (PWV), brachial distensibility (BrachD), augmentation index (AIx), and epidermal growth factor receptor (eGFR) continuously and categorically as hyperfiltration (eGFR ≥ 135 mL/min/1.73 m(2)).

RESULTS

Adolescents with type 1 diabetes who met 1-3 goals, had significantly greater (P < 0.05) baseline PWV (5.1 ± 0.1 vs. 5.4 ± 0.1 m/s), follow-up PWV (5.5 ± 0.1 vs. 5.7 ± 0.1 m/s), greater follow-up eGFR (104 ± 2 vs. 116 ± 3 mL/min/1.73 m(2)), and greater odds of renal hyperfiltration at follow-up (odds ratio (OR): 20.0, 95% confidence interval (CI): 3.8-105.2) compared to those who met 4-6 goals after adjusting for Tanner stage, sex, age, and diabetes duration. No statistically significant differences in the cardiorenal outcomes were observed between adolescents with type 1 diabetes who met 4-6 goals and non-diabetic controls (n = 96).

CONCLUSIONS

In adolescents with type 1 diabetes, baseline ADA/ISPAD goal achievement was associated with cardiorenal protection at baseline and 2-yr follow-up.

Genetic modulation of diabetic nephropathy among mouse strains with Ins2 Akita mutation

Diabetic nephropathy (DN) is a major complication of diabetes and the leading cause of end‐stage renal disease. DN is characterized by changes in kidney structure and function but the underlying genetic and molecular factors are poorly understood. We used a mouse diversity panel to explore the genetic basis of DN traits in mice carrying the Ins2 Akita mutation. Twenty‐eight Akita strains were generated by breeding this panel to DBA/2.Akita mice. Male F1 diabetic and nondiabetic littermates were evaluated for DN‐related traits. Urine albumin‐to‐creatinine ratios (ACRs), volume and cystatin C as well as blood urea nitrogen and lipoprotein levels varied significantly among the diabetic strains. For most Akita strains, ACR values increased 2‐ to 6‐fold over euglycemic control values. However, six strains exhibited changes in ACR exceeding 10‐fold with two strains (NOD/ShiLt and CBA) showing 50‐ to 83‐ fold increases. These increases are larger than previously reported among available DN mouse models establishing these strains as useful for additional studies of renal function. ACRs correlated with cystatin C (P = 0.0286), a measure of hyperfiltration and an interstitial tubular marker associated with DN onset in humans suggesting that tubule damage as well as podocyte‐stress contributed to reduced kidney function assessed by ACR. Although large changes were seen for ACRs, severe nephropathology was absent. However, glomerular hypertrophy and collagen IV content were found to vary significantly among strains suggesting a genetic basis for early onset features of DN. Our results define the range of DN phenotypes that occur among common inbred strains of mice.

Diabetic nephropathy (DN) is characterized by changes in kidney structure and function but the underlying genetic and molecular factors are poorly understood. We used a mouse diversity panel to explore the genetic basis of DN traits in mice carrying the Ins2 Akita mutation. Twenty‐eight Akita strains on different genetic backgrounds were evaluated for DN‐related traits and the results define the range of DN phenotypes that occur among common inbred strains of mice.

In patients with type 1 diabetes simultaneous pancreas and kidney transplantation preserves long-term kidney graft ultrastructure and function better than transplantation of kidney alone

AIMS/HYPOTHESIS

In patients with type 1 diabetes and end-stage renal disease (ESRD) we aimed to determine whether long-term normoglycaemia, as achieved by successful simultaneous pancreas and kidney (SPK) transplantation, would preserve kidney graft structure and function better than live donor kidney (LDK) transplantation alone.

METHODS

Estimated GFR (eGFR) was calculated in SPK (n = 25) and LDK (n = 17) recipients in a stable phase 3 months after transplantation and annually during follow-up. Kidney graft biopsies were obtained at follow-up for measurement of glomerular volume (light microscopy), glomerular basement membrane (GBM) and podocyte foot process widths and mesangial volume fraction (electron microscopy).

RESULTS

SPK and LDK recipients were similar in age and diabetes duration at engraftment. Donor age was higher in the LDK group. Median follow-up time was 10.1 years. Mean HbA1c levels during follow-up were 5.5 ± 0.4% (37 ± 5 mmol/mol) and 8.3 ± 1.5% (68 ± 16 mmol/mol) in the SPK and LDK group, respectively (p < 0.001). Compared with SPK recipients, LDK recipients had wider GBM (369 ± 109 nm vs 281 ± 57 nm; p = 0.008) and increased mesangial volume fraction (median 0.23 [range 0.13-0.59] vs 0.16 [0.10-0.41]; p = 0.007) at follow-up. Absolute eGFR change from baseline was -11 ± 21 and -23 ± 15 ml min(-1) 1.73 m(-2) (p = 0.060), whereas eGFR slope was -1.1 (95% CI -1.7, -0.5) and -2.6 (95% CI -3.1, -2.1) ml min(-1) 1.73 m(-2) per year in the SPK and LDK group, respectively (p = 0.001).

CONCLUSIONS/INTERPRETATION

In patients with type 1 diabetes and long-term normoglycaemia after successful SPK transplantation, kidney graft ultrastructure and function were better preserved compared with LDK transplantation alone.

Glomerular structural-functional relationship models of diabetic nephropathy are robust in type 1 diabetic patients

Studies of structural-functional relationships have improved understanding of the natural history of diabetic nephropathy (DN). However, in order to consider structural end points for clinical trials, the robustness of the resultant models needs to be verified. This study examined whether structural-functional relationship models derived from a large cohort of type 1 diabetic (T1D) patients with a wide range of renal function are robust. The predictability of models derived from multiple regression analysis and piecewise linear regression analysis was also compared. T1D patients (n = 161) with research renal biopsies were divided into two equal groups matched for albumin excretion rate (AER). Models to explain AER and glomerular filtration rate (GFR) by classical DN lesions in one group (T1D-model, or T1D-M) were applied to the other group (T1D-test, or T1D-T) and regression analyses were performed. T1D-M-derived models explained 70 and 63% of AER variance and 32 and 21% of GFR variance in T1D-M and T1D-T, respectively, supporting the substantial robustness of the models. Piecewise linear regression analyses substantially improved predictability of the models with 83% of AER variance and 66% of GFR variance explained by classical DN glomerular lesions alone. These studies demonstrate that DN structural-functional relationship models are robust, and if appropriate models are used, glomerular lesions alone explain a major proportion of AER and GFR variance in T1D patients.

Early diabetic nephropathy in type 1 diabetes: new insights

PURPOSE OF REVIEW

Despite improvements in glycemic and blood pressure control in patients with type 1 diabetes, diabetic nephropathy remains the most common cause of chronic kidney disease worldwide. A major challenge in preventing diabetic nephropathy is the inability to identify high-risk patients at an early stage, emphasizing the importance of discovering new therapeutic targets and implementation of clinical trials to reduce diabetic nephropathy risk.

RECENT FINDINGS

Limitations of managing patients with diabetic nephropathy with renin-angiotensin-aldosterone system blockade have been identified in recent clinical trials, including the failure of primary prevention studies in T1D and the demonstration of harm with dual renin-angiotensin-aldosterone system blockade. Fortunately, several new targets, including serum uric acid, insulin sensitivity, vasopressin, and sodium-glucose cotransporter-2 inhibition, are promising in the prevention and treatment of diabetic nephropathy.

SUMMARY

Diabetic nephropathy is characterized by a long clinically silent period without signs or symptoms of disease. There is an urgent need for improved methods of detecting early mediators of renal injury, to ultimately prevent the initiation and progression of diabetic nephropathy. In this review, we will focus on early diabetic nephropathy and summarize potential new therapeutic targets.

Long-term outcomes after organ transplantation in diabetic end-stage renal disease

Patients with type 1 diabetic end-stage renal disease (ESRD) may be offered single kidney transplantation from a live donor (LDK) or a deceased donor (DDK) to replace the lost kidney function. In the latter setting the patient may also receive a simultaneous pancreas together with a kidney from the same donor (SPK). Also in some cases a pancreas after kidney may be offered to those who have previously received a kidney alone (PAK). The obvious benefit of a successful SPK transplantation is that the patients not only recover from uremia but also obtain normal blood glucose control without use of insulin or other hypoglycemic agents. Accordingly, this combined procedure has become an established treatment for type 1 diabetic patients with ESRD. Adequate long-term blood glucose control may theoretically lead to reduced progression or even reversal of microvascular complications. Another potential beneficial effect may be improvement of patient and kidney graft survival. Development of diabetic complications usually takes a decade to develop and accordingly any potential benefits of a pancreas transplant will not easily be disclosed during the first decade after transplantation. The purpose of the review is to assess the present literature of outcomes after kidney transplantation in patients with diabetic ESRD, with our without a concomitant pancreas transplantation. The points of interest given in this review are microvascular complications, graft outcomes, cardiovascular outcomes and mortality.

TLR4 activation promotes podocyte injury and interstitial fibrosis in diabetic nephropathy

Toll like receptor (TLR) 4 has been reported to promote inflammation in diabetic nephropathy. However the role of TLR4 in the complicated pathophysiology of diabetic nephropathy is not understood. In this study, we report elevated expression of TLR4, its endogenous ligands and downstream cytokines, chemokines and fibrogenic genes in diabetic nephropathy in WT mice with streptozotocin (STZ) diabetes. Subsequently, we demonstrated that TLR4^−/− mice were protected against the development of diabetic nephropathy, exhibiting less albuminuria, inflammation, glomerular hypertrophy and hypercellularity, podocyte and tubular injury as compared to diabetic wild-type controls. Marked reductions in interstitial collagen deposition, myofibroblast activation (α-SMA) and expression of fibrogenic genes (TGF-β and fibronectin) were also evident in TLR4 deficient mice. Consistent with our in vivo results, high glucose directly promoted TLR4 activation in podocytes and tubular epithelial cells in vitro, resulting in NF-κB activation and consequent inflammatory and fibrogenic responses. Our data indicate that TLR4 activation may promote inflammation, podocyte and tubular epithelial cell injury and interstitial fibrosis, suggesting TLR4 is a potential therapeutic target for diabetic nephropathy.

Chronic NSAID use and long-term decline of renal function in a prospective rheumatoid arthritis cohort study

OBJECTIVES

Non-steroidal anti-inflammatory drugs (NSAIDs) may cause kidney damage. This study assessed the impact of prolonged NSAID exposure on renal function in a large rheumatoid arthritis (RA) patient cohort.

METHODS

Renal function was prospectively followed between 1996 and 2007 in 4101 RA patients with multilevel mixed models for longitudinal data over a mean period of 3.2 years. Among the 2739 'NSAID users' were 1290 patients treated with cyclooxygenase type 2 selective NSAIDs, while 1362 subjects were 'NSAID naive'. Primary outcome was the estimated glomerular filtration rate according to the Cockroft-Gault formula (eGFRCG), and secondary the Modification of Diet in Renal Disease and Chronic Kidney Disease Epidemiology Collaboration formula equations and serum creatinine concentrations. In sensitivity analyses, NSAID dosing effects were compared for patients with NSAID registration in ≤/>50%, ≤/>80% or ≤/>90% of assessments.

FINDINGS

In patients with baseline eGFRCG >30 mL/min, eGFRCG evolved without significant differences over time between 'NSAID users' (mean change in eGFRCG -0.87 mL/min/year, 95% CI -1.15 to -0.59) and 'NSAID naive' (-0.67 mL/min/year, 95% CI -1.26 to -0.09, p=0.63). In a multivariate Cox regression analysis adjusted for significant confounders age, sex, body mass index, arterial hypertension, heart disease and for other insignificant factors, NSAIDs were an independent predictor for accelerated renal function decline only in patients with advanced baseline renal impairment (eGFRCG <30 mL/min). Analyses with secondary outcomes and sensitivity analyses confirmed these results.

CONCLUSIONS

NSAIDs had no negative impact on renal function estimates but in patients with advanced renal impairment.

Pathophysiology of the diabetic kidney

Diabetes mellitus contributes greatly to morbidity, mortality, and overall health care costs. In major part, these outcomes derive from the high incidence of progressive kidney dysfunction in patients with diabetes making diabetic nephropathy a leading cause of end-stage renal disease. A better understanding of the molecular mechanism involved and of the early dysfunctions observed in the diabetic kidney may permit the development of new strategies to prevent diabetic nephropathy. Here we review the pathophysiological changes that occur in the kidney in response to hyperglycemia, including the cellular responses to high glucose and the responses in vascular, glomerular, podocyte, and tubular function. The molecular basis, characteristics, and consequences of the unique growth phenotypes observed in the diabetic kidney, including glomerular structures and tubular segments, are outlined. We delineate mechanisms of early diabetic glomerular hyperfiltration including primary vascular events as well as the primary role of tubular growth, hyperreabsorption, and tubuloglomerular communication as part of a "tubulocentric" concept of early diabetic kidney function. The latter also explains the "salt paradox" of the early diabetic kidney, that is, a unique and inverse relationship between glomerular filtration rate and dietary salt intake. The mechanisms and consequences of the intrarenal activation of the renin-angiotensin system and of diabetes-induced tubular glycogen accumulation are discussed. Moreover, we aim to link the changes that occur early in the diabetic kidney including the growth phenotype, oxidative stress, hypoxia, and formation of advanced glycation end products to mechanisms involved in progressive kidney disease.

Insulin therapy with personal insulin pumps and early angiopathy in children with type 1 diabetes mellitus

OBJECTIVE

Assessment of the effect of a treatment method change from multiple daily insulin injection (MDI) to continuous subcutaneous insulin infusion (CSII) on the development of early angiopathy in children with T1DM with or without retinopathy.

METHODS

The study pump group involved 32 diabetic children aged 14.8, with the initial HbA1c level of 8.3%, previously treated by MDI. The patients were examined before pump insertion and after 3 and 6 months of CSII. We assessed HbA1c level, carotid artery intima-media thickness (c-IMT), and flow-mediated dilatation (FMD) of the brachial artery. The pump group was compared to a group of eight teenagers with diagnosed nonproliferative retinopathy, treated with MDI.

RESULTS

HbA1c in the entire group was found to improve in the second and in the third examination. During 6 months of CSII, FMD increased and IMT decreased. Retinopathic adolescents had significantly thicker IMT and lower FMD compared to baseline results of the pump group. Treatment intensification in the retinopathy-free children enhanced these differences.

CONCLUSIONS

CSII is associated with lower IMT and higher FMD. Whether on the long-run CSII is superior to MDI to delay the occurrence of diabetes late complications remains to be explained.

Adherence and renal biopsy feasibility in the Renin Angiotensin-System Study (RASS) primary prevention diabetes trial

AIMS

Enhancing adherence in research trials is fundamental to the proper testing of treatment hypotheses.

METHODS

Regimen and follow-up adherence as well as factors associated with adherence in the Renin Angiotensin-System Study (RASS) diabetic nephropathy primary prevention trial were evaluated. Adherence to medication (i.e., pill count), follow-up visits, and follow-up renal biopsies was evaluated.

RESULTS

89.8% of subjects completed the second renal biopsy. 96% of follow-up visits were attended within prescribed time windows. Mean medication adherence was 85.6%. Subgroup analyses revealed greater declines in the least adherent participants over time. Factors associated with greater adherence levels included older age, type 1 diabetes (TIDM) duration, lower HbA1c and blood pressure, GFR, ethnicity, and participants', principal investigators' (PI), and trial coordinators' (TC) baseline predictions of adherence.

CONCLUSIONS

T1DM patients without nephropathy were willing to take experimental medications and undergo repeat renal biopsies. Although overall adherence was excellent, patterns of adherence varied among participants, suggesting the need to better track adherence and to develop customized and targeted approaches for promoting adherence to clinical research regimens. Staff subjective predictions of adherence were imprecise, supporting need for further development of adherence predictors.

Uric acid lowering to prevent kidney function loss in diabetes: the preventing early renal function loss (PERL) allopurinol study

Diabetic kidney disease causes significant morbidity and mortality among people with type 1 diabetes (T1D). Intensive glucose and blood pressure control have thus far failed to adequately curb this problem and therefore a major need for novel treatment approaches exists. Multiple observations link serum uric acid levels to kidney disease development and progression in diabetes and strongly argue that uric acid lowering should be tested as one such novel intervention. A pilot of such a trial, using allopurinol, is currently being conducted by the Preventing Early Renal Function Loss (PERL) Consortium. Although the PERL trial targets T1D individuals at highest risk of kidney function decline, the use of allopurinol as a renoprotective agent may also be relevant to a larger segment of the population with diabetes. As allopurinol is inexpensive and safe, it could be cost-effective even for relatively low-risk patients, pending the completion of appropriate trials at earlier stages.

Renal lesions predict progression of diabetic nephropathy in type 1 diabetes

Whether early glomerular, tubulointerstitial, vascular, and global glomerulosclerotic lesions can predict progression of diabetic nephropathy is not well defined. Here, we sought to determine whether renal structural parameters predict the development of proteinuria or ESRD after long-term follow-up. We measured several renal structures in kidney biopsies from 94 normoalbuminuric patients with longstanding type 1 diabetes using unbiased morphometric methods. Greater width of the glomerular basement membrane and higher levels of glycated hemoglobin were independent predictors of progression to diabetic nephropathy in this normoalbuminuric cohort. Moreover, none of these patients with type 1 diabetes who had glomerular basement membrane widths within the normal range developed proteinuria and/or ESRD. In conclusion, careful quantitative assessment of kidney biopsies in normoalbuminuric patients with type 1 diabetes adds substantially to the prediction of progression to clinical diabetic nephropathy.

Morphologic features of declining renal function in type 1 diabetes

Progressive renal dysfunction is a major complication of type 1 diabetes. Studying relationships between evolution of diabetic nephropathy lesions and renal functional alterations (structural-functional relationships) helps to better understand the natural history of diabetic nephropathy. The focus of this review is our current understanding of the interplay between morphologic changes of diabetic nephropathy and glomerular filtration rate (GFR) loss. These morphologic changes often may not progress in parallel to each other or to the decline in GFR or increase in albumin excretion rate (AER). Quantitative measures of renal (mainly glomerular) structural changes can predict a substantially larger fraction of AER variability compared with that of GFR, especially using linear correlation analyses. However, nonlinear models better fit the structural-functional relationships across a wide range of GFRs and AERs. Currently, there are insufficient longitudinal data to show which structural changes predict the slope of GFR decline in type 1 diabetic patients. Based on cross-sectional studies, however, such a predictor would be about 10% more robust in patients whose GFR was 45 mL/min/1.73 m(2) or greater if comprised of a composite of glomerular, tubular, and interstitial parameters versus glomerular changes alone. For a slowly progressive disease, such as diabetic nephropathy, in which, especially in the earlier stages, it takes a long time for GFR to decline substantially, such predictors are much needed and, if sufficiently precise, could potentially serve as a surrogate of renal functional decline in clinical trials.

Global renal gene expression profiling analysis in B2-kinin receptor null mice: impact of diabetes

Diabetic nephropathy (DN), the leading cause of end-stage renal failure, is clinically manifested by albuminuria and a progressive decline in glomerular filtration rate. The risk factors and mechanisms that contribute to the development and progression of DN are still incompletely defined. To address the involvement of bradykinin B₂-receptors (B₂R) in DN, we used a genome wide approach to study the effects of diabetes on differential renal gene expression profile in wild type and B₂R knockout (B₂R^−/−) mice. Diabetes was induced with streptozotocin and plasma glucose levels and albumin excretion rate (AER) were measured at predetermined times throughout the 23 week study period. Longitudinal analysis of AER indicated that diabetic B₂R^−/−D null mice had a significantly decreased AER levels compared to wild type B₂R^+/+D mice (P = 0.0005). Results from the global microarray study comparing gene expression profiles among four groups of mice respectively: (B₂R^+/+C, B₂R^+/+D, B₂R^−/−C and B₂R^−/−D) highlighted the role of several altered pathological pathways in response to disruption of B₂R and to the diabetic state that included: endothelial injury, oxidative stress, insulin and lipid metabolism and inflammatory process with a marked alteration in the pro-apoptotic genes. The findings of the present study provide a global genomics view of biomarkers that highlight the mechanisms and putative pathways involved in DN.

Safety and complications of percutaneous kidney biopsies in 715 children and 8573 adults in Norway 1988-2010

BACKGROUND AND OBJECTIVES

Skepticism about performing renal biopsies is often because of uncertainty regarding risk of complications. The aim of this study was to evaluate safety and relevant complications of renal biopsies in pediatric and adult patients in a large national registry study.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Kidney biopsies reported in the Norwegian Kidney Biopsy Registry from 1988 to 2010 were included. Risk factors for major complications (blood transfusion and/or surgical or catheter intervention) were analyzed using logistic regression statistics.

RESULTS

Of the 9288 biopsies included, 715 were from children, and 8573 were from adults (≥18 years). Median age was 49 years (range=2 weeks to 94 years). Gross hematuria appeared after biopsy in 1.9% of the patients; 0.9% of patients needed blood transfusion, and 0.2% of patients needed surgical intervention/catheterization. The frequencies were 1.9%, 0.9%, and 0.2% in adults and 1.7%, 0.1% and 0.1% in children, respectively; 97.9% of the biopsies were without complications. In unadjusted analyses, risk factors for major complications were age>60 years, estimated GFR<60 ml/min per 1.73 m(2), systolic hypertension, acute renal failure, and smaller clinical center size (<30 biopsies/yr). Adjusted analyses (adjusted for age and/or estimated GFR) showed higher odds ratios (OR) only for smaller clinical center (OR=1.60 [1.02-2.50]) and low estimated GFR (estimated GFR=30-59 ml/min per 1.73 m(2) [OR=4.90 (1.60-14.00)] and estimated GFR<30 ml/min per 1.73 m(2) [OR 15.50 (5.60-43.00)]).

CONCLUSIONS

Percutaneous renal biopsy is a low-risk procedure in all ages. Reduced estimated GFR and smaller center size are associated with an increased risk of major complications.

Coenzyme Q10 prevents GDP-sensitive mitochondrial uncoupling, glomerular hyperfiltration and proteinuria in kidneys from db/db mice as a model of type 2 diabetes

AIMS/HYPOTHESIS

Increased oxygen consumption results in kidney tissue hypoxia, which is proposed to contribute to the development of diabetic nephropathy. Oxidative stress causes increased oxygen consumption in type 1 diabetic kidneys, partly mediated by uncoupling protein-2 (UCP-2)-induced mitochondrial uncoupling. The present study investigates the role of UCP-2 and oxidative stress in mitochondrial oxygen consumption and kidney function in db/db mice as a model of type 2 diabetes.

METHODS

Mitochondrial oxygen consumption, glomerular filtration rate and proteinuria were investigated in db/db mice and corresponding controls with and without coenzyme Q10 (CoQ10) treatment.

RESULTS

Untreated db/db mice displayed mitochondrial uncoupling, manifested as glutamate-stimulated oxygen consumption (2.7 ± 0.1 vs 0.2 ± 0.1 pmol O(2) s(-1) [mg protein](-1)), glomerular hyperfiltration (502 ± 26 vs 385 ± 3 μl/min), increased proteinuria (21 ± 2 vs 14 ± 1, μg/24 h), mitochondrial fragmentation (fragmentation score 2.4 ± 0.3 vs 0.7 ± 0.1) and size (1.6 ± 0.1 vs 1 ± 0.0 μm) compared with untreated controls. All alterations were prevented or reduced by CoQ10 treatment. Mitochondrial uncoupling was partly inhibited by the UCP inhibitor GDP (-1.1 ± 0.1 pmol O(2) s(-1) [mg protein](-1)). UCP-2 protein levels were similar in untreated control and db/db mice (67 ± 9 vs 67 ± 4 optical density; OD) but were reduced in CoQ10 treated groups (43 ± 2 and 38 ± 7 OD).

CONCLUSIONS/INTERPRETATION

db/db mice displayed oxidative stress-mediated activation of UCP-2, which resulted in mitochondrial uncoupling and increased oxygen consumption. CoQ10 prevented altered mitochondrial function and morphology, glomerular hyperfiltration and proteinuria in db/db mice, highlighting the role of mitochondria in the pathogenesis of diabetic nephropathy and the benefits of preventing increased oxidative stress.

Microalbuminuria in relation to metabolic control and blood pressure in adolescents with type 1 diabetes

INTRODUCTION

The objective of this study was to assess the frequency of microalbuminuria and the relationship with other risk factors for the development of diabetic nephropathy.

MATERIAL AND METHODS

Our cross-section study involved a group of 60 adolescence of both sexes, mean age 15.3 ±2.43 years with mean duration of diabetes 7.74 ±3.44 years. Albumin excretion rate was measured on 2-3 samples of the first morning urine in the period below 6 months and persistent microalbuminuria was defined if its increased in two out of three urine specimens. Ambulatory blood pressure was monitored (ABPM, SpaceLabs 90207).

RESULTS

Microalbuminuria developed in 13.3% of adolescents with mostly completed sexual development, statistically significantly poorer metabolic control (9.79% vs. 8.7%) and higher BMI (23.59 kg/m(2) vs. 20.85 kg/m(2)) than in the patients with normoalbuminuria. The mean night-time systolic blood pressure (SBP) was statistically significantly higher in microalbuminuric patients than in normoalbuminurics. The nocturnal dip was reduced in 41.7% of our patients; 38.5% of nondippers were in normoalbuminuric and 62.5% in microalbuminuric patients.

CONCLUSIONS

Diabetic adolescents require particular attention in order to minimize the factors such as high HbA(1c), elevated body mass index and night-time SBP in the development of incipient nephropathy.

Microvascular complications assessment in adolescents with 2- to 5-yr duration of type 1 diabetes from 1990 to 2006

OBJECTIVE

Microvascular complications occur in adolescents with type 1 diabetes, although guidelines vary as to when screening should commence and prevalence data for those with ≤5-yr duration are limited. We therefore investigated trends in prevalence of early microvascular complications over 17 yr.

RESEARCH DESIGN AND METHODS

819 adolescents (54% female) aged 11-17 yr with 2- to 5-yr diabetes duration were assessed for complications at a tertiary pediatric diabetes clinic between 1990 and 2006. Early retinopathy was detected using seven-field fundal photography, albumin excretion rate (AER) by timed overnight urine collections and peripheral nerve function by thermal/vibration threshold at the foot. Results were analyzed by age, time period of assessment, and duration.

RESULTS

Early retinopathy declined from 1990 to 2002 (16-7%, p < 0.01), then remained unchanged until 2006. Early elevation of AER (≥7.5 µg/min) and microalbuminuria (≥20 µg/min) did not change over time, whereas peripheral nerve abnormalities increased (14-28%, p < 0.01). Median hemoglobin A1c improved (8.7-8.2%, p < 0.01), in parallel with increased total daily insulin dose and injections per day (p < 0.01). Body mass index standard deviation score increased over time (0.55-0.79, p < 0.01). In multivariate logistic regression, early retinopathy was associated with earlier time period [odds ratio (OR) 0.68, confidence interval (CI) 0.55-0.85, p < 0.01] and older age (OR 1.19, CI 1.02-1.39, p = 0.03). AER ≥ 7.5 µg/min was associated with older age (1.19, 1.06-1.34, p < 0.01) and longer diabetes duration (OR 1.28, CI 1.02-1.62, p = 0.04) and height-adjusted peripheral nerve abnormalities with later time period (OR 1.26, CI 1.05-1.50, p = 0.01).

CONCLUSIONS

Early complications are not uncommon in adolescents with 2- to 5-yr diabetes duration, despite more intensive management in recent years.

Sex-related differences in the long-term risk of microvascular complications by age at onset of type 1 diabetes

AIMS/HYPOTHESIS

This study examined sex-related differences in the cumulative risk of proliferative retinopathy (PR) and end-stage renal disease (ESRD) over 40 years of duration of type 1 diabetes according to age at diabetes onset.

METHODS

We assessed 4,416 patients from the Finnish Diabetic Nephropathy Study population. Kaplan-Meier analysis was used to provide cumulative incidence rates and Cox regression analyses for HRs.

RESULTS

There were no sex-related differences in the cumulative incidence of ESRD in patients diagnosed with type 1 diabetes between 0 to 4 and 5 to 9 years. Thereafter the risk started to diverge. The cumulative incidence of ESRD in patients diagnosed between 10 to 14 and ≥15 years was 17.4% (95% CI 13.4-21.2) and 13.0% (9.6-16.2) respectively in women, while in men it was 32.2% (28.0-36.1) and 24.6% (20.8-28.1) respectively. The respective HRs were (onset at 10 to 14 years) 1.9 (p < 0.0001) and (onset at ≥15 years) 1.8 (p < 0.001), respectively. There was no difference in the risk of PR between men and women diagnosed between 0 and 4 years of age, but progressive sex-related differences in the cumulative incidence of PR were observed with increasing age at onset. The HRs for men in the age-at-onset groups 5 to 9, 10 to 14 and ≥15 years of age were 1.3 (95% CI 1.0-1.6), 1.3 (1.1-1.6) and 2.1 (1.6-2.6) compared with women in these groups, respectively.

CONCLUSIONS/INTERPRETATION

The difference between the sexes with regard to risk of diabetic microvascular complications is highly dependent on the age at onset of diabetes. The risk of ESRD and PR risk doubled in men compared with women when age at onset was ≥15 years.

Association between testosterone, estradiol and sex hormone binding globulin levels in men with type 1 diabetes with nephropathy

Male sex is a risk factor for development and progression of diabetic nephropathy; however, the relationship between sex hormone levels and diabetic nephropathy in type 1 diabetic men is unknown. This was a prospective follow-up study as part of the nationwide Finnish Diabetic Nephropathy (FinnDiane) Study; 297 patients were followed for 5.9+/-1.5 years. Serum total testosterone (Tt) and estradiol (Te), calculated free testosterone (cFt) and estradiol (cFe) and sex hormone binding globulin were measured at baseline and correlated with urinary albumin excretion rate, estimated glomerular filtration rate and markers of metabolic syndrome. Diabetes without renal disease was associated with decreased Tt (p<0.001), Te (p<0.001) and cFt (p=0.001) levels compared with healthy non-diabetic men. With progression of renal disease from micro- to macroalbuminuria, this decrease in serum Tt was even more pronounced. Cox regression showed that cFt and cFe were independent predictors of the progression from macroalbuminuria to end-stage renal disease. Our study shows that men with type 1 diabetes exhibit dysregulated sex hormone levels, which is most pronounced in men with progressive renal disease, suggesting that sex hormones may play a role in the pathogenesis of diabetic nephropathy associated with type 1 diabetes.

Genetic variant in the promoter of connective tissue growth factor gene confers susceptibility to nephropathy in type 1 diabetes

BACKGROUND The evidence for genetic susceptibility in the pathogenesis of diabetic nephropathy is well recognised, but the genes involved remain to be identified. It is hypothesised that mutations within the gene encoding connective tissue growth factor (CTGF/CCN2) will increase the propensity of diabetic subjects to develop nephropathy. METHODS AND RESULTS Genomic screening was performed for single nucleotide polymorphisms (SNPs) within the CTGF gene in 862 subjects from the DCCT/EDIC cohort of type 1 diabetes. A novel SNP was identified in the promoter region that changes a C-G at the position -20. The frequency of GG genotype in microalbuminuric patients (albumin excretion rate (AER) >40 mg/24 h) is significantly greater than diabetics with AER <40 mg/24 h, p<0.0001. The relative risk (RR) to develop microalbuminuria in diabetic subjects with the polymorphism is 3X higher than diabetic subjects without the polymorphism (RR 3.142, 95% CI 1.9238 to 5.1249; p<0.05). Kaplan-Meier survival curves demonstrated that the GG genotype group developed microalbuminuria and macroalbuminuria at a more rapid rate than the GC or CC genotypes. Functional studies demonstrated that the basal activity of the substituted allele/promoter (-20 GG allele) was significantly greater than that of the wild type promoter (-20 CC genotype). This higher level of basal activity of substituted allele CTGF/CCN2 promoter was abrogated upon suppression of Smad1 levels, indicating that SNP region in the CTGF/CCN2 promoter plays a vital role in the gene expression. CONCLUSIONS These findings provide the first evidence that variants within the promoter region of the CTGF/CCN2 gene predisposes diabetic subjects to develop albuminuria and demonstrate that Smad1 [corrected] controls the expression of CTGF/CCN2 promoter through this region.

Age is a determinant of acute hemodynamic responses to hyperglycemia and angiotensin II in humans with uncomplicated type 1 diabetes mellitus

Hyperglycemia is associated with hemodynamic changes in type 1 diabetes (DM), acting in part through renin-angiotensin system activation. Since aging is associated with vascular dysfunction in DM, we hypothesized that acute hemodynamic responses to clamped hyperglycemia and infused ANG II would be exaggerated in older adults compared with a group of adolescent/young adults with type 1 DM. Renal hemodynamic function, blood pressure, and arterial stiffness were assessed in adolescent/young adults ( n = 34; mean age: 18 ± 3 yr) and older adults ( n = 32; mean age: 45 ± 9 yr). Studies were performed during clamped euglycemia (4–6 mmol/l) and hyperglycemia (9–11 mmol/l). Renal and systemic hemodynamic responses to ANG II were measured during clamped euglycemia in diabetic subjects. ANG II responses were also assessed in a cohort of non-DM subjects ( n = 97; mean age: 26; age range: 18–40 yr). Older DM adults exhibited higher baseline blood pressure, arterial stiffness, and renal vascular resistance, and lower glomerular filtration rate (GFR) and effective renal plasma flow, compared with adolescent/young DM adults ( P < 0.05). Clamped hyperglycemia was associated with exaggerated peripheral and renal hemodynamic responses uniquely in older DM adults; only GFR increased in adolescent/young DM adults. ANG II infusion also produced exaggerated vasoconstrictive responses in older DM adults vs. adolescent/young DM adults ( P < 0.05). The independent effect of age on hemodynamic responses to hyperglycemia and ANG II was confirmed using multivariate regression analysis in DM subjects ( P < 0.05), and results were still significant when participants were matched for DM duration. Age-related alterations in hemodynamic function and ANG II response were not observed in healthy non-DM control subjects. Acute hemodynamic responses to clamped hyperglycemia and ANG II were exaggerated in older subjects with type 1 DM, highlighting an important interaction between age and factors that contribute to the pathogenesis of acute vascular dysfunction in DM.