Spice Up Your Kidney: A Review on the Effects of Capsaicin in Renal Physiology and Disease

Capsaicin, the organic compound which attributes the spicy flavor and taste of red peppers and chili peppers, has been extensively studied for centuries as a potential natural remedy for the treatment of several illnesses. Indeed, this compound exerts well-known systemic pleiotropic effects and may thus bring important benefits against various pathological conditions like neuropathic pain, rhinitis, itching, or chronic inflammation. Yet, little is known about the possible biological activity of capsaicin at the kidney level, as this aspect has only been addressed by sparse experimental investigations. In this paper, we aimed to review the available evidence focusing specifically on the effects of capsaicin on renal physiology, as well as its potential benefits for the treatment of various kidney disorders. Capsaicin may indeed modulate various aspects of renal function and renal nervous activity. On the other hand, the observed experimental benefits in preventing acute kidney injury, slowing down the progression of diabetic and chronic kidney disease, ameliorating hypertension, and even delaying renal cancer growth may set the stage for future human trials of capsaicin administration as an adjuvant or preventive therapy for different, difficult-to-treat renal diseases.

Childhood Obesity: Insight into Kidney Involvement

This review examines the impact of childhood obesity on the kidney from an epidemiological, pathogenetic, clinical, and pathological perspective, with the aim of providing pediatricians and nephrologists with the most current data on this topic. The prevalence of childhood obesity and chronic kidney disease (CKD) is steadily increasing worldwide, reaching epidemic proportions. While the impact of obesity in children with CKD is less pronounced than in adults, recent studies suggest a similar trend in the child population. This is likely due to the significant association between obesity and the two leading causes of end-stage renal disease (ESRD): diabetes mellitus (DM) and hypertension. Obesity is a complex, systemic disease that reflects interactions between environmental and genetic factors. A key mechanism of kidney damage is related to metabolic syndrome and insulin resistance. Therefore, we can speculate about an adipose tissue-kidney axis in which neurohormonal and immunological mechanisms exacerbate complications resulting from obesity. Adipose tissue, now recognized as an endocrine organ, secretes cytokines called adipokines that may induce adaptive or maladaptive responses in renal cells, leading to kidney fibrosis. The impact of obesity on kidney transplant-related outcomes for both donors and recipients is also significant, making stringent preventive measures critical in the pre- and post-transplant phases. The challenge lies in identifying renal involvement as early as possible, as it is often completely asymptomatic and not detectable through common markers of kidney function. Ongoing research into innovative technologies, such as proteomics and metabolomics, aims to identify new biomarkers and is constantly evolving. Many aspects of pediatric disease progression in the population of children with obesity still require clarification. However, the latest scientific evidence in the field of nephrology offers glimpses into various new perspectives, such as genetic factors, comorbidities, and novel biomarkers. Investigating these aspects early could potentially improve the prognosis of these young patients through new diagnostic and therapeutic strategies. Hence, the aim of this review is to provide a comprehensive exploration of the pathogenetic mechanisms and prevalent pathological patterns of kidney damage observed in children with obesity.

Hyperkalemia in CKD: an overview of available therapeutic strategies

Hyperkalemia (HK) is a life-threatening condition that often occurs in patients with chronic kidney disease (CKD). High serum potassium (sKsK) is responsible for a higher risk of end-stage renal disease, arrhythmias and mortality. This risk increases in patients that discontinue cardio-nephroprotective renin-angiotensin-aldosterone system inhibitor (RAASi) therapy after developing HK. Hence, the management of HK deserves the attention of the clinician in order to optimize the therapeutic strategies of chronic treatment of HK in the CKD patient. The adoption in clinical practice of the new hypokalaemic agents patiromer and sodium zirconium cyclosilicate (SZC) for the prevention and chronic treatment of HK could allow patients, suffering from heart failure and chronic renal failure, to continue to benefit from RAASi therapy. We have updated a narrative review of the clear variables, correct definition, epidemiology, pathogenesis, etiology and classifications for HK among non-dialysis CKD (ND CKD) patients. Furthermore, by describing the prognostic impact on mortality and on the progression of renal damage, we want to outline the strategies currently available for the control of potassium (K+) plasma levels.

Urinary Marinobufagenin in Patients with Non-Advanced Chronic Kidney Disease: A Cross-Sectional Study

Background and Objectives: The global prevalence of chronic kidney disease (CKD) is on the rise, posing important challenges for healthcare systems. Thus, the search for new factors potentially involved in the pathogenesis, progression and complications of early CKD remains urgent. Marinobufagenin (MBG) is a natriuretic endogenous cardiotonic steroid, and increased circulating levels of it may accelerate kidney damage. In this study, we explored the possible clinical significance of measuring urinary marinobufagenin (uMBG) in patients with non-advanced CKD. Materials and Methods: One hundred and eight adult CKD patients (mean age 71.6 ± 10 years, 70.4% male; mean eGFR 40.54 ± 17 mL/min/1.73 m2) were enrolled in this cross-sectional study. uMBG was measured together with a series of clinical, anthropometric, laboratory and instrumental analyses. Twenty-five healthy matched subjects served as controls for the uMBG measurement. Results: The uMBG values were lower in the patients with CKD as compared to those of the controls (0.37 [IQR: 0.25-0.45] vs. 0.64 [0.46-0.78] nmol/L. p = 0.004), and a significant trend in eGFR levels was noticed across the decreasing uMBG tertiles (p = 0.03). Regarding the correlation analyses, the uMBG values remained robustly associated with the eGFR in multivariate models employing either uMBG or eGFR as the dependent variable (β = 0.248; p = 0.01 and β = 0.139; p = 0.04, respectively). Besides the eGFR, the independent predictors of uMBG values in this population were the use of statins (β = -0.326; p = 0.001), the presence of diabetes (β = 0.243; p = 0.009) and urine sodium (β = 0.204; p = 0.01). Conclusions: Reduced uMBG excretion may reflect impaired renal clearance, which may contribute to the detrimental effects attributed to this hormone due to systemic accumulation. Future studies are needed to clarify the biological mechanisms placing uMBG at the crossroad of sodium intake and the presence of diabetes in CKD-suffering individuals and to verify whether a statin treatment may somewhat limit the detrimental effects of MBG in the presence of impaired renal function.

Marinobufagenin, Left Ventricular Hypertrophy and Residual Renal Function in Kidney Transplant Recipients

BACKGROUND

Left ventricular hypertrophy (LVH), which is a pervasive complication of end-stage kidney disease (ESKD), persists in some uremic individuals even after kidney transplantation (Ktx), contributing to worsening CV outcomes. Marinobufagenin (MBG), an endogenous steroid cardiotonic hormone endowed with natriuretic and vasoconstrictive properties, is an acknowledged trigger of uremic cardiomyopathy. However, its clinical significance in the setting of Ktx remains undefined.

METHODS

In a cohort of chronic Ktx recipients (n = 40), we assessed circulating MBG together with a thorough clinical and echocardiographic examination. Forty matched haemodialysis (HD) patients and thirty healthy subjects served as controls for MBG measurements. Patients were then prospectively followed up to 12 months and the occurrence of an established cardio-renal endpoint (death, CV events, renal events, graft rejection) was recorded.

RESULTS

Median MBG plasma levels were lower in Ktx as compared with HD patients (p = 0.02), but higher as compared with healthy controls (p = 0.0005). Urinary sodium (β = 0.423; p = 0.01) and eGFR (β = -0.324; p = 0.02) were the sole independent predictors of MBG in this cohort, while a strong correlation with left ventricular mass index (LVMi), found in univariate analyses (R = 0.543; p = 0.0007), gained significance only in multivariate models not including eGFR. Logistic regression analyses indicated MBG as a significant predictor of the combined endpoint (OR 2.38 [1.10-5.12] per each 1 nmoL/L increase; p = 0.01), as well as eGFR, LVMi, serum phosphate and proteinuria.

CONCLUSIONS

Ktx recipients display altered MBG levels which are influenced by sodium balance, renal impairment and the severity of LVH. Thus, MBG might represent an important missing link between reduced graft function and pathological cardiac remodelling and may hold important prognostic value for improving cardio-renal risk assessment.

MO354: Selenium-Binding Protein 1 (Sepp1) as an Early Sensitive Biomarker of Acute Kidney Injury in Patients Undergoing Cardiopulmonary Bypass

BACKGROUND AND AIMS

Acute kidney injury (AKI) often occurs in patients undergoing major cardiac surgery with cardiopulmonary bypass (CPB). Despite renal ischemia remains the key trigger, sustained oxidative stress is now acknowledged as a significant contributor. Selenium-binding protein 1 (SEPP1) is an intracellular protein whose blood levels increase in response to systemic cardiovascular and oxidative stress, as well as in the course of chronic kidney injury.

METHOD

In this pilot prospective study, we measured circulating SEPP1 levels in a cohort of 45 patients undergoing cardiac surgery with CPB in order to test its possible role in predicting the following occurrence of AKI. Serum samples of SEPP1 were collected before CPB (baseline) and at 4, 8 and 12 h after the end of the procedure and measured with a commercially available ELISA kit.

RESULTS

In the whole cohort, there was a significant statistical trend in SEPP1 levels from baseline to 12 h after CPB [39 (10–45) versus 3263 (1886–5042) ng/mL; P < 0.0001]. Within 48 h from CPB end, 12/45 patients (27%) developed AKI, as defined as an increase in serum creatinine >0.3 mg/dL or an absolute 1.5-fold increase from baseline and/or a reduced urine output (<0.5 mL/kg/h). Circulating SEPP1 displayed an earlier and more prominent increase in AKI patients as compared with others [4 h SEPP1: 52 (39–233) versus 546 (260–1000) ng/mL; P < 0.001]. 8 h SEPP1: 638 (437–1254) versus 1959 (1055–5303) ng/mL; P < 0.001; difference between overall trends: P < 0.001 (Fig. 1). At ROC analyses, either 4 or 8 h circulating SEPP1 had a remarkable diagnostic capacity in identifying AKI patients (AUCs 0.854 and 0.790, both P < 0.001). The crude OR of AKI in patients with 4 and 8 h SEPP1 above the best ROC-derived cut-off values (178 and 1840 ng/mL, respectively) was 22 (95%CI 2.5–192.9) and 14.5 (95% CI 2.9–71.2), respectively. At multivariate analysis, such a risk was independent from potential confounders, including CPB duration, clamping time and age.

CONCLUSION

Increased SEPP1 levels in patients undergoing CPB may reflect a sustained response to systemic oxidative stress. Such a response becomes more prominent when renal damage is also occurring. Studies on larger and more heterogeneous cohorts are needed to confirm whether SEPP1 may be a candidate as an early and specific biomarker of AKI in this high-risk setting.

MO732: Circulating Omentin-1 and Subclinical Atherosclerosis in Chronic Hemodialysis Patients: A Pilot Study

BACKGROUND AND AIMS

Chronic haemodialysis (HD) patients are notoriously at high risk for cardiovascular mortality and morbidity. Omentin-1 (OME-1) is an adipocytokine produced by adipose tissue, whose levels are altered in various dysmetabolic conditions, such as obesity and type 2 diabetes mellitus. Beyond this, nowadays there is evidence indicating that this cytokine plays a crucial role in the genesis and progression of systemic atherosclerosis since it may inhibit plaque formation. With this background in mind, we run a pilot investigation to evaluate the possible correlation between circulating OME-1 levels and mean intimal thickness (IMT) in a small, homogeneous cohort of patients treated by HD (‘HD patients’).

METHOD

From a source cohort of 45 HD patients, we selected 27 individuals suitable to be enrolled. These patients had a dialysis vintage > 6 mo.,  were on a regular 4 h/3 times week HD regimen and had stable clinical conditions. OME-1 levels were measured in their blood by the ELISA together with common laboratory and clinical parameters before starting a mid-week HD session. All the patients then underwent carotid Doppler ultrasound for IMT measurement. A total of 18 healthy subjects were the controls.

RESULTS

In the whole cohort, mean IMT values were 0.75 ± 0.12 mm. However, 8/27 patients (29.6%) presented a pathological IMT (>1 mm). Circulating OME-1 levels in the whole HD cohort were increased as compared with controls [763 (367–1423) versus 371 (228–868) ng/mL; P = 0.03]. However, HD patients with pathological IMT presented, on average, lower OME-1 levels as compared with others [483.25 (168.7–1743) versus 1155 (286–2324); P = 0.05]. In ROC analyses, OME-1 values ≤ 840 ng/mL held an 83.3 sensitivity and 66.7 specificity (AUC 0.716, 95% confidence interval 0.506–0.946) in identifying HD patients with pathological carotid thickening.

CONCLUSION

OME-1 may play a direct role in the atherosclerosis process also in HD patients. Further studies on larger and more heterogeneous HD cohorts are needed to confirm the usefulness of OME-1 plasma levels as potential biomarkers for diagnosing subclinical atherosclerosis and for stratifying the risk of atherosclerosis progression in high-CV risk in HD patients.

[Study designs adopted in epidemiology of chronic diseases]

Clinical research is gaining interest among healthcare professionals. This review provides an in-depth analysis of key study designs used in epidemiology, which can help researchers use the right methodology to design and conduct a research project. Case-control studies evaluate the association between an exposure to a specific risk factor and a study endpoint. Cross-sectional studies are indicated to assess the prevalence of a given risk factor. Cohort studies consist of longitudinal studies, in which a population is followed over time. These studies allow to evaluate the association between a risk factor and one or more study endpoints which are absent at the time of the population enrollment. Experimental studies are designed to test the efficacy and safety of an intervention. Generally, they include two groups of individuals who are assigned to either an experimental treatment or a standard treatment, respectively. Meta-analyses are studies that summarize the evidence already published concerning a specific research question and constitute an important source for evidence-based medicine and for the production and updating of guidelines.

MO413EFFECTS OF CHRONIC, LONG-TERM ACE-INHIBITOR TREATMENT ON CYTOKINE STORM AND RENAL FUNCTION AFTER CARDIO-PULMONARY BYPASS: A PROSPECTIVE OBSERVATIONAL STUDY

Background and Aims

Cardiopulmonary bypass (CPB) may trigger organs damage, including kidney injury, due to a massive cytokine release. In this observational, prospective study, we have analyzed the possible impact of chronic treatment with ACE-Inhibitors (ACE-I) on the inflammatory response and renal function after CPB.

Method

Sixty-nine patients undergoing major cardiac surgery with CPB were enrolled. Patients were stratified according to long-term (>6 mo.) ACE-I use (n=38) or not (n=31). The primary endpoint was to analyze the changes in their IL-1 alpha, IL-1beta, IL-2, IL-4, IL-6, IL-8, IL-10, TNF alpha, EGF and VEGF plasma levels. Secondary (renal) endpoints were: postoperative acute kidney injury (AKI), recovery of baseline GFR values and the absolute changes in renal function indexes.

Results

After CPB, IL-1alpha, IL-1beta, IL-4 and TNF-alpha remained stable overtime, while a significant decrease in IL-2 plasma levels was noticed in the ACE-I group (p=0.01). IL-6 and IL-8 plasma levels increased after surgery and tended to decrease after 48h. IL-10 plasma levels showed a similar variation, but both their rise and decrease were more pronounced in patients under ACE-I treatment (p=0.007). Finally, VEGF and EGF showed a marked initial decrease with a tendency to normalization 10 days after surgery (p for trend ranging from 0.01 to 0.001) (Figure 1-2).

The occurrence of AKI within 2 days after surgery, the rate of GFR recovery and the absolute changes in renal function indexes were not statistically different between groups (Figure 3).

Conclusion

Chronic, long-term ACE-I treatment may influence the inflammatory response following CPB. On the other hand, this drug class apparently has neutral impact on perioperative renal outcomes.

MO791HIGH-SENSITIVITY CARDIAC TROPONIN I CORRELATES WITH THE CARDIAC DYSFUNCTION AND WITH THE SEVERITY OF ANEMIA IN DIALYSIS PATIENTS

Background and Aims

Several evidences demonstrate that chronic dialysis treatment alters troponin levels, even in the absence of an acute myocardial event, although the underlying causes remain largely unclear. In this small pilot study, we aimed at analyzing high sensitivity troponin T (HsTnT) in a cohort of dialysis patients to identify the potential clinical predictors.

Method

HsTnT levels were measured together with common laboratory and clinical parameters in 39 chronic dialysis patients (middle age: 65±12 aa; 82% M; 30 in hemodialysis and 9 in peritoneal dialysis). The patients underwent also a complete echocardiography assessment.

Results

HsTnT levels were higher than normal reference values (median 46.1 ng/L IQR 33.5-84.3),but showing no differences between hemodialysis and peritoneal dialysis patients (p=0.19). At correlation analyses, HsTnT were strongly associated with beta2-MCG (R=0.43; p=0.008), Hemoglobin (r=-0.47; p=0.002) and, in particular, with some echocardiography parameters such as ejection fraction (R=-0.29; p=0.05), E/E’ratio (R=0.56; p=0.006) and LAVI (R=0.41; p=0.05) Figure 1.

Conclusion

In a small cohort of dialysis patients, high HsTnt levels were at the crossroad between the severity of functional heart dysfunction and anemia. Larger studies are advocated to further clarify the role of HsTnT as a potential biomarker reflecting the anemic cardiorenal syndrome which characterizes uremic subjects.

MO462TIME-TRAJECTORIES OF RENAL FUNCTION AND OUTCOMES IN ELDERLY INDIVIDUALS WITH CKD OF VARIOUS ETIOLOGY

Background and Aims

Despite hypertension ranks among the leading causes of chronic kidney disease (CKD), the impact of chronic hypertensive nephropathy, the so-called “nephrosclerosis” (NS), on CKD progression towards end-stage kidney disease (ESKD) is often unpredictable, particularly in older populations. We run a prospective, observational study to define renal function patterns and outcomes in elderly individuals with or without NS-related CKD.

Method

304 elderly patients with already established CKD (mean age 69±4 y; mean eGFR 44.2±19.6 mL/min/1.73 m2; male= 64.1%), followed in our outpatients’ clinic were categorized according to the etiology of CKD. NS was defined as the presence of CKD associated with long-term essential hypertension, hypertensive retinopathy, left ventricular hypertrophy and minimal proteinuria. Time-trajectories in eGFR (CKD-Epi) were computed over a 4-year follow-up. In addition, we analysed the occurrence of a composite outcome of doubling of serum creatinine, eGFR reduction≥ 25% and/or ESKD needing dialysis or kidney transplantation.

Results

CKD was secondary to nephrosclerosis (CKD-NS) in 220 (72.3%) patients. Among the remaining 84 (27.7%), glomerular/diabetic diseases were the most frequent cause of CKD (47.6%). In the whole cohort, the average estimated annual GFR slope was of 1.8 mL/min/1.73 m2. eGFR decline was slower in CKD-NS as compared with the one of others (1.4 vs. 3.4 mL/min/1.73 m2; p<0.001. Figure 1). The composite renal outcome during follow-up (median 36 mo.; range 6-48) occurred less frequently among elderly with CKD-NS (16/204 vs 14/70; p=0.01 Crude HR 0.43, 95%CI 0.22-0.85) and was associated at logistic analyses with etiology of CKD, serum total cholesterol, serum LDL cholesterol levels and glycemia (p ranging from 0.01 to 0.04).

Conclusion

Despite being highly prevalent in the elderly, NS is associated with a more favorable renal disease course as compared with other conditions. Therapeutic efforts to delay CKD progression in older populations should go beyond just optimizing blood pressure control and focus more on concomitant diseases.