Defining, Treating, and Understanding Chronic Kidney Disease--A Complex Disorder

Dioscorea nipponica Makino: A comprehensive review of its chemical composition and pharmacology on chronic kidney disease

Chronic kidney disease (CKD) is a widespread ailment that significantly impacts global health. It is characterized by high prevalence, poor prognosis, and substantial healthcare costs, making it a major public health concern. The current clinical treatments for CKD are not entirely satisfactory, leading to a high demand for alternative therapeutic options. Chinese herbal medicine, with its long history, diverse varieties, and proven efficacy, offers a promising avenue for exploration. One such Chinese herbal medicine, Dioscorea nipponica Makino (DNM), is frequently used to treat kidney diseases. In this review, we have compiled studies examining the mechanisms of action of DNM in the context of CKD, focusing on five primary areas: improvement of oxidative stress, inhibition of renal fibrosis, regulation of metabolism, reduction of inflammatory response, and regulation of autophagy.

Metabolic and hormonal responses to chronic blood-flow restricted resistance training in chronic kidney disease: a randomized trial

Maintenance of glycemic and lipemic homeostasis can limit the progression of diabetic kidney disease. Resistance training (RT) is effective in controlling glycemia and lipemia in kidney disease; however, the effect of RT with blood flow restriction (RT+BFR) on these metabolic factors has not been investigated. We aimed to verify if chronic (6 months) RT and RT+BFR performed by patients with stage-2 chronic kidney disease (CKD) improves their glycemic homeostasis and immunometabolic profiles. Patients with CKD under conservative treatment (n = 105 (33 females)) from both sexes were randomized into control (n = 35 (11 females); age 57.6 ± 5.2 years), RT (n = 35 (12 females); age 58.0 ± 6.2 years), and RT+BFR (n = 35 (10 females); 58.0 ± 6.4 years) groups. Chronic RT or RT+BFR (6 months) was performed 3 times per week on non-consecutive days with training loading adjusted every 2 months, RT 50%-60%-70% of 1RM, and RT+BFR 30%-40%+50% of 1RM and fixed repetition number. Renal function was estimated with the glomerular filtration rate and serum albumin level. Metabolic, hormonal, and inflammatory assessments were analyzed from blood samples. Six months of RT and RT+BFR were similarly effective in improving glucose homeostasis and hormone mediators of glucose uptake (e.g., irisin, adiponectin, and sirtuin-1), decreasing pro-inflammatory and fibrotic proteins, and attenuating the progression of estimated glomerular filtration rate. Thus, RT+BFR can be considered an additional exercise modality to be included in the treatment of patients with stage 2 chronic kidney disease. Trial registration number: U1111-1237-8231. URL: http://www.ensaiosclinicos.gov.br/rg/RBR-3gpg5w/, no. RBR-3gpg5w. Novelty: Glycemic regulation induced by resistance training prevents the progression of CKD. Chronic RT and RT+BFR promote similar changes in glycemic regulation. RT and RT+BFR can be considered as non-pharmacological tools for the treatment of CKD.

Association of Serum Thyroid Hormones with the Risk and Severity of Chronic Kidney Disease Among 3563 Chinese Adults

Background

Chronic kidney disease (CKD) is a global health problem with an increasing prevalence. We explored the association of serum thyroid hormones with the risk and severity of CKD among Chinese adults.

Material/Methods

This retrospective study involved 3563 participants. CKD was diagnosed according to the clinical practice guidelines of the 2012 Kidney Disease Improving Global Outcomes guidelines. Effect-size estimates are expressed as odds ratio (OR) and 95% confidence interval (CI).

Results

Given the strong magnitude of correlation, only 3 thyroid hormones were analyzed: free triiodothyronine (FT3), free thyroxin (FT4), and thyroid-stimulating hormone (TSH). After propensity score matching on age, sex, diabetes, and hypertension, per 0.2 pg/mL increase in FT3 was significantly associated with 35–38% reduced risk of CKD at stage 1–4, and per 0.3 ng/dL increase in FT4 was only significantly associated with 21% reduced risk of CKD at stage 5 (OR, 95% CI: 0.79, 0.69–0.89), and per 0.5 μIU/mL increment in TSH increased the risk of CKD stage 5 by 8% (1.08, 1.02–1.14). Importantly, 3 thyroid hormones acted interactively, particularly for the interaction between FT3 and FT4 in predicting CKD at stage 5 (OR, 95% CI: 1.81, 1.30–2.55 for high FT3-low FT4, 17.72, 7.18–43.74 for low FT3-high FT4, and 22.28, 9.68–51.30 for low FT3-low FT4).

Conclusions

Our findings indicate that serum FT3 can be used as an early-stage biomarker for CKD, and FT4 and TSH can be used as advanced-stage biomarkers among Chinese adults.

Impact of chronic kidney disease and anemia on health-related quality of life and work productivity: analysis of multinational real-world data

Background

Reductions in health-related quality of life (HRQoL) in patients with chronic kidney disease (CKD) are thought to be exacerbated by the low hemoglobin (Hb) levels that define anemia, a common complication of CKD. The current analysis evaluated the impact of anemia on HRQoL and work productivity in patients with non-dialysis dependent and dialysis-dependent CKD using real-world data.

Methods

Data were collected in France, Germany, Italy, Spain, the UK, the USA and China in 2012–2018 in the Adelphi Real World Disease Specific Programme™ for CKD, a large, cross-sectional, survey of physicians and their patients. Patients completed three patient-reported outcomes (PRO) instruments: the EuroQol 5-Dimension 3-level (EQ-5D-3 L), the Kidney Disease Quality of Life (KDQOL-36) instrument and the Work Productivity and Activity Impairment questionnaire. PROs were assessed by CKD stage and Hb levels, and regression analyses were performed with CKD stage and Hb level as independent variables and PROs as outcome variables, while adjusting for age, sex, CKD stage, comorbidities and cardiovascular risk.

Results

Overall, 5276 patients participated in the survey, including 28% stage 4 and 36% dialysis patients. Patients with lower Hb levels more often reported problems/issues on all EQ-5D-3 L domains (p < 0.0001). Regression analyses showed significant associations between lower Hb levels and the probability of low (< 0.8) EQ-5D-3 L utility scores (p < 0.0001) and low visual analog scale scores (p < 0.05), indicating poorer health status. Associations were seen even when adjusting for CKD stage and other potential confounding factors. Significant associations were observed between Hb level and the 12-Item Short-Form Health Survey (SF-12) Physical Component Summary, SF-12 Mental Component Summary and the three KDQOL-36 subscales (all p < 0.0001), and were confirmed using linear regression analyses adjusting for CKD stage and other potential confounders. Numerically greater work productivity losses and greater activity impairment were observed with lower Hb levels.

Conclusions

Lower Hb levels worsen the impact of CKD on HRQoL, and are associated with lower work productivity in patients with CKD. Assessment and treatment of anemia should be recognized as a key component of integral CKD management throughout all stages of the disease.

Application of nintedanib and other potential anti-fibrotic agents in fibrotic diseases

Nintedanib, a Food and Drug Administration-approved drug for the treatment of patients with idiopathic pulmonary fibrosis (IPK), inhibits both tyrosine kinase receptors and non-receptor kinases, and block activation of platelet-derived growth factor receptors, fibroblast growth factor receptor, vascular endothelial growth factor receptors, and Src family kinases. Preclinical and clinical studies have revealed the potent anti-fibrotic effect of nintedanib in IPK in human and animal models. Recent preclinical studies have also demonstrated the inhibitory effect of nintedanib on the development and progression of tissue fibrosis in other organs, including liver, kidney, and skin. The anti-fibrotic actions of nintedanib occur through a number of mechanisms, including blocking differentiation of fibroblasts to myofibroblasts, inhibition of epithelial-mesenchymal transition, and suppression of inflammation and angiogenesis. In this article, we summarize the mechanisms and efficacy of nintedanib in the treatment of fibrotic diseases in animal models and clinical trials, provide an update on recent advances in the development of other novel antifibrotic agents in preclinical and clinical study, and offer our perspective about the possible clinical application of these agents in fibrotic diseases.

New Therapies for the Treatment of Renal Fibrosis

Renal fibrosis is the common pathway for progression of chronic kidney disease (CKD) to end stage of renal disease. It is now widely accepted that the degree of renal fibrosis correlates with kidney function and CKD stages. The key cellular basis of renal fibrosis includes activation of myofibroblasts, excessive production of extracellular matrix components, and infiltration of inflammatory cells. Many cellular mechanisms responsible for renal fibrosis have been identified, and some antifibrotic agents show a greater promise in slowing down and even reversing fibrosis in animal models; however, translating basic findings into effective antifibrotic therapies in human has been limited. In this chapter, we will discuss the effects and mechanisms of some novel antifibrotic agents in both preclinical studies and clinical trials.

Short-term dexamethasone treatment transiently, but not permanently, attenuates fibrosis after acute-to-chronic kidney injury

Background

Acute kidney injury (AKI) is an underestimated, yet important, risk factor for the development of chronic kidney disease (CKD). Persistence of inflammation after a renal ischemic injury has been observed, both in experimental models and patients, and is thought to be an important mechanisms underlying progression of acute-to-chronic renal injury. Temporary suppression of inflammation immediately after AKI might therefore be a good first-line therapeutic strategy towards a better long term outcome.

Methods

Male C57Bl/6 J mice (Charles River, 10–12 weeks of age) underwent warm (36 °C body temperature) unilateral ischemia-reperfusion of the kidney for 21 min, after which treatment with intraperitoneal injection of the corticosteroid dexamethasone (10 mg/kg) was initiated for 3 weeks. Both at that time point and after an additional 3 week post-treatment follow up period, fibrosis was quantified by collagen I gene expression and immunostaining, as well as gene expression analysis of fibrosis-related genes Tgfβ, Ccn2 (Ctgf), Pai-1 and Ccn3. Furthermore, inflammation was evaluated by Tnfα gene expression and protein expression of the F4/80 macrophage marker and the α-SMA fibroblast marker. Lastly, renal histopathology was quantified by a morphometric analysis of the tubulointerstitial area.

Results

Treatment with dexamethasone attenuated development of fibrosis, as evidenced by reduced collagen I gene expression and immunostaining, in combination with reduced gene expression of the pro-fibrotic Ccn2 and increased expression of the anti-fibrotic Ccn3. The effects of dexamethasone on renal fibrosis persisted during the 3 week follow up period, as evidenced by stagnation of collagen I deposition in the ischemic kidney, in contrast to vehicle-treatment, where progression of fibrosis was observed. However, expression levels of the pro-fibrotic genes re-approached those of vehicle-treated injured kidneys suggesting that the effects of dexamethasone on fibrosis beyond the treatment period are temporary.

Conclusion

A short term anti-inflammatory therapy with dexamethasone only transiently attenuates ischemia induced fibrosis. Prolonged or persistent anti-inflammatory treatment seems warranted to achieve long term benefit.

Electronic supplementary material

The online version of this article (10.1186/s12882-018-1151-7) contains supplementary material, which is available to authorized users.

PEGylated pUR4/FUD peptide inhibitor of fibronectin fibrillogenesis decreases fibrosis in murine Unilateral Ureteral Obstruction model of kidney disease

Fibronectin is a blood and extracellular matrix glycoprotein that plays important roles in wound healing and fibrosis since it controls the deposition of collagen and other extracellular matrix molecules and is a substrate for infiltrating lymphocytes. Using a high-affinity fibronectin-binding peptide (FUD/pUR4) that inhibits fibronectin deposition into extracellular matrix (ECM), we tested the ability of a PEGylated FUD/pUR4 (PEG-FUD) to inhibit fibrosis in the Unilateral Ureteral Obstruction (UUO) kidney disease model. Fibronectin fibrillogenesis assays, using human fibroblasts and human proximal tubular epithelial cultures, showed that PEG-FUD can inhibit fibronectin fibrillogenesis in vitro with an IC50 similar to unconjugated FUD, in the order of 20–35 nM. In contrast, a mutated FUD (mFUD) conjugated to PEG that lacked activity did not inhibit fibronectin assembly, even at 20 μM. The in vivo activity of PEG-FUD was tested in the murine UUO model by daily subcutaneous injection of 12.5 mg/kg for 7 days until harvest at day 10. Control treatments included saline, PEG, unconjugated FUD, and PEG-mFUD. Immunoblotting studies showed that fibronectin was enriched in the extracellular matrix fractions of extracted UUO kidneys, compared to contralateral untreated kidneys. In vivo, PEG-FUD significantly decreased fibronectin by ~70% in UUO kidneys as determined by both IHC and immunoblotting, respectively. In contrast, neither PEG-mFUD, PEG, nor saline had any significant effect. PEG-FUD also decreased collagens I and III and CD45-expressing cells (leukocytes) by ~60% and ~50%, as ascertained by picrosirius red staining and IHC, respectively. Immunoblotting studies also showed that the fibronectin remaining after PEG-FUD treatment was intact. Utilizing a custom-made polyclonal antibody generated against pUR4/FUD, intact PEG-FUD was detected by immunoblotting in both the ECM and lysate fractions of UUO kidneys. No adverse reaction or event was noted with any treatment. In summary, these studies suggest that PEG-FUD reached the kidneys without degradation, and decreased fibronectin incorporation into interstitial tissue. Decreased fibronectin was accompanied by a decrease in collagen and leukocyte infiltration. We propose that PEG-FUD, a specific inhibitor of fibronectin assembly, may be a candidate therapeutic for the treatment of fibrosis in kidney diseases.

Sociodemographic associations with abnormal estimated glomerular filtration rate (eGFR) in a large Canadian city: a cross-sectional observation study

BACKGROUND

Chronic kidney disease (CKD) is often asymptomatic in its early stages but is indicated and is diagnosed with an estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73m2. Certain sociodemographic groups are known to be at risk for CKD, but it is unclear if there are strong associations between these at risk groups with abnormal eGFR test results in Canada. Using only secondary laboratory and Census data, geospatial variation and sociodemographic associations with abnormal eGFR result rate were investigated in Calgary, Alberta.

METHODS

Secondary laboratory data from all adult community patients who received an eGFR test result were collected from Calgary Laboratory Service's Laboratory Information System, which is the sole supplier of laboratory services for the large metropolitan city. Group-level sociodemographic variables were inferred by combining laboratory data with the 2011 Canadian Census data. Poisson regression and relative risk (RR) were used to calculate associations between sociodemographic variables with abnormal eGFR. Geographical distribution of abnormal eGFR result rates were analyzed by geospatial analysis using ArcGIS.

RESULTS

Of the 346,663 adult community patients who received an eGFR test result, 28,091 were abnormal (8.1%; eGFR < 60 ml/min/1.73m2). Geospatial analysis revealed distinct geographical variation in abnormal eGFR result rates in Calgary. Women (RR = 1.11, P < 0.0001), and the elderly (age ≥ 70 years; P < 0.0001) were significantly associated with an increased risk for CKD, while visible minority Chinese (RR = 0.73, P = 0.0011), South Asians (RR = 0.67, P < 0.0001) and those with a high median household income (RR = 0.88, P < 0.0001) had a significantly reduced risk for CKD.

CONCLUSIONS

Presented here are significant sociodemographic risk associations, and geospatial clustering of abnormal eGFR result rates in a large metropolitan Canadian city. Using solely publically available secondary laboratory and Census data, the results from this study aligns with known sociodemographic risk factors for CKD, as certain sociodemographic variables were at a higher risk for having an abnormal eGFR test result, while others were protective in this analysis.

Rotenone ameliorates chronic renal injury caused by acute ischemia/reperfusion

Acute kidney injury (AKI) has been widely recognized as an important risk factor leading to the occurrence and progression of chronic kidney disease (CKD). Thus, development of the strategies in retarding the transition of AKI to CKD is becoming a hot research field. Recently, accumulating evidence suggested a pathogenic role of mitochondrial dysfunction in both AKI and CKD. Therefore, in the present study, we evaluated the effect of mitochondrial complex 1 inhibition by rotenone on the chronic renal damage induced by acute ischemia-reperfusion. The mice were treated with 45 min unilateral renal ischemia and reperfusion (I/R) to induce an acute renal injury. After three days of I/R injury, rotenone at a dose of 200 ppm in food was administered to the mice. Strikingly, after three weeks treatment with rotenone, we found that the unilateral I/R-induced tubular damage, tubulointerstitial fibrosis were all attenuated by rotenone as determined by the tubular injury score, Masson staining, and the levels of collagen-I, collagen-III, fibronectin, PAI-1, and TGF-β. Meanwhile, the enhanced inflammatory markers of TNF-α, IL-1β, IL-6, and IL-18 and apoptotic markers of Bax and caspase-3 were all significantly blunted by inhibiting mitochondrial complex-1. Moreover, rotenone treatment also partially protected the mitochondria as shown by the restoration of mitochondrial SOD (SOD2), ATPB, and mitochondrial DNA copy number. These findings suggested that inhibition of mitochondrial complex-1 activity by rotenone could retard the progression of AKI to CKD probably via protecting the mitochondrial function to some extent.

Wearable sensors: can they benefit patients with chronic kidney disease?

INTRODUCTION

This article ponders upon wearable medical measurement devices in relation to Chronic Kidney Disease (CKD) and its' associated comorbidities - and whether these might benefit CKD-patients. We aimed to map the intersection(s) of nephrology and wearable sensor technology to help technologists understand medical aspects, and clinicians to understand technological possibilities that are available (or soon will become so). Areas covered: A structured literature search on main comorbidities and complications CKD patients suffer from, was used to steer mini-reviews on wearable sensor technologies clustered around 3 themes being: Cardiovascular-related, diabetes-related and physical fitness/frailty. This review excludes wearable dialysis - although also strongly enabled by miniaturization - because that highly important theme deserves separate in-depth reviewing. Expert commentary: Continuous progress in integrated electronics miniaturization enormously lowered price, size, weight and energy consumption of electronic sensors, processing power, memory and wireless connectivity. These combined factors boost opportunities for wearable medical sensors. Such devices can be regarded as enablers for: Remote monitoring, influencing human behaviour (exercise, dietary), enhanced home care, remote consults, patient education and peer networks. However, to make wearable medical devices succeed, the challenge to fit them into health care structures will be dominant over the challenge to realize the bare technologies themselves.

The clinical characteristics of posterior reversible encephalopathy syndrome in patients with chronic renal failure

Few studies have investigated posterior reversible encephalopathy syndrome (PRES) in patients with chronic renal failure (CRF). The present study analyzed the clinical manifestations, laboratory examinations and imaging features of PRES in patients with CRF. A total of 42 patients with CRF with or without PRES were recruited in the current retrospective case-control study. Patient data taken prior to the onset of PRES in patients with CRF and PRES (n=21) were collected and analyzed. At the same time, data from patients with CRF but without PRES (n=21) were also analyzed. Brain magnetic resonance imaging (MRI) scans were collected from patients in the PRES group. The mean blood pressure of patients in the PRES group was significantly higher than that of the control group (systolic blood pressure: 172±15 mmHg vs. 135±14 mmHg, P<0.01; diastolic blood pressure: 95±16 mmHg vs. 64±13 mmHg, P<0.01). Furthermore, compared with the control group, mean serum albumin (Alb) and hemoglobin (Hb) concentrations in the PRES group were significantly lower (Alb: 29.1±5.3 g/l vs. 34.6±6.1 g/l, P=0.001; Hb: 74±16 g/l vs. 89±28 g/l, P=0.037). By contrast, mean LDH concentration was significantly higher in the PRES group (LDH: 336±141 U/l vs. 235±89 U/l, P=0.004). In the PRES group, 24 h urine volume was significantly lower in the PRES group than in the control group (24 h urine volume: 651±520 ml vs. 982±518 ml, P=0.046). No significant differences in levels of serum potassium (4.5±0.6 mmol/l vs. 4.4±0.5 mmol/l, P=0.377), sodium (138.3±4.9 mmol/l vs. 139.0±6.8 mmol/l, P=0.325), calcium (2.0±0.24 mmol/l vs. 1.9±0.24 mmol/l, P=0.673), alanine aminotransferase; (24±14 U/l vs. 18±8 U/l, P=0.975); aspartate aminotransferase (29±11 U/l vs. 24±9 U/l, P=0.619) and uric acid (448±148 µmol/l vs. 378±116 µmol/l, P=0.599) were found between the two groups. PRES is a relatively common nervous system complication arising in patients with CRF. Certain biochemical markers, including Hb and Alb, may be associated with PRES. Diagnosing PRES is difficult as computed tomography (CT) brain scans may be normal and MRI scans, which are more sensitive than CT scans at diagnosing PRES, are not always performed in patients with CRF. Thus, brain MRI scans should be taken first in such patients when PRES is suspected.

Unilateral Renal Ischemia-Reperfusion as a Robust Model for Acute to Chronic Kidney Injury in Mice

Acute kidney injury (AKI) is an underestimated, yet important risk factor for development of chronic kidney disease (CKD). Even after initial total recovery of renal function, some patients develop progressive and persistent deterioration of renal function and these patients are more likely to progress to end-stage renal disease (ESRD). Animal models are indispensable for unravelling the mechanisms underlying this progression towards CKD and ESRD and for the development of new therapeutic strategies in its prevention or treatment. Ischemia (i.e. hypoperfusion after surgery, bleeding, dehydration, shock, or sepsis) is a major aetiology in human AKI, yet unilateral ischemia-reperfusion is a rarely used animal model for research on CKD and fibrosis. Here, we demonstrate in C57Bl/6J mice, by both histology and gene expression, that unilateral ischemia-reperfusion without contralateral nephrectomy is a very robust model to study the progression from acute renal injury to long-term tubulo-interstitial fibrosis, i.e. the histopathological hallmark of CKD. Furthermore, we report that the extent of renal fibrosis, in terms of Col I, TGFβ, CCN2 and CCN3 expression and collagen I immunostaining, increases with increasing body temperature during ischemia and ischemia-time. Thus, varying these two main determinants of ischemic injury allows tuning the extent of the long-term fibrotic outcome in this model. Finally, in order to cover the whole practical finesse of ischemia-reperfusion and allow model and data transfer, we provide a referenced overview on crucial technical issues (incl. anaesthesia, analgesia, and pre- and post-operative care) with the specific aim of putting starters in the right direction of implementing ischemia in their research and stimulate them, as well as the community, to have a critical view on ischemic literature data.