Fibroblast growth factor 23, endothelium biomarkers and acute kidney injury in critically-ill patients

A Combined Biomarker That Includes Plasma Fibroblast Growth Factor 23, Erythropoietin, and Klotho Predicts Short- and Long-Term Morbimortality and Development of Chronic Kidney Disease in Critical Care Patients with Sepsis: A Prospective Cohort

Acute Kidney Injury (AKI) is a frequent complication in intensive care unit (ICU) patients that increases mortality and chronic kidney disease (CKD) development. AKI is associated with elevated plasma fibroblast growth factor 23 (FGF23), which can be modulated by erythropoietin (EPO) and Klotho. We aimed to evaluate whether a combined biomarker that includes these molecules predicted short-/long-term outcomes. We performed a prospective cohort of ICU patients with sepsis and previously normal renal function. They were followed during their inpatient stay and for one year after admission. We measured plasma FGF23, EPO, and Klotho levels at admission and calculated a combined biomarker (FEK). A total of 164 patients were recruited. Of these, 50 (30.5%) had AKI at admission, and 55 (33.5%) developed AKI within 48 h. Patients with AKI at admission and those who developed AKI within 48 h had 12- and 5-fold higher FEK values than non-AKI patients, respectively. Additionally, patients with higher FEK values had increased 1-year mortality (41.9% vs. 18.6%, p = 0.003) and CKD progression (26.2% vs. 8.3%, p = 0.023). Our data suggest that the FEK indicator predicts the risk of AKI, short-/long-term mortality, and CKD progression in ICU patients with sepsis. This new indicator can improve clinical outcome prediction and guide early therapeutic strategies.

Heat stress combined with lipopolysaccharide induces pulmonary microvascular endothelial cell glycocalyx inflammatory damage in vitro

Heat stroke is a life-threatening disease with high mortality and complications. Endothelial glycocalyx (EGCX) is essential for maintaining endothelial cell structure and function as well as preventing the adhesion of inflammatory cells. Potential relationship that underlies the imbalance in inflammation and coagulation remains elusive. Moreover, the role of EGCX in heat stroke-induced organ injury remained unclear. Therefore, the current study aimed to illustrate if EGCX aggravates apoptosis, inflammation, and oxidative damage in human pulmonary microvascular endothelial cells (HPMEC). Heat stress and lipopolysaccharide (LPS) were employed to construct in vitro models to study the changes of glycocalyx structure and function, as well as levels of heparansulfate proteoglycan (HSPG), syndecan-1 (SDC-1), heparansulfate (HS), tumor necrosis factor-α (TNF-α), interleukin (IL)-6, Von Willebrand factor (vWF), endothelin-1 (ET-1), occludin, E-selectin, vascular cell adhesion molecule-1 (VCAM-1), and reactive oxygen species (ROS). Here, we showed that heat stress and LPS devastated EGCX structure, activated EGCX degradation, and triggered oxidative damage and apoptosis in HPMEC. Stimulation of heat stress and LPS decreased expression of HSPG, increased levels of SDC-1 and HS in culture supernatant, promoted the production and release of proinflammation cytokines (TNF-α and IL-6,) and coagulative factors (vWF and ET-1) in HPMEC. Furthermore, Expressions of E-selection, VCAM-1, and ROS were upregulated, while that of occludin was downregulated. These changes could be deteriorated by heparanase, whereas they meliorated by unfractionated heparin. This study indicated that EGCX may contribute to apoptosis and heat stroke-induced coagulopathy, and these effects may have been due to the decrease in the shedding of EGCX.

Platelets in Renal Disease

Kidney disease is a major global health concern, affecting millions of people. Nephrologists have shown interest in platelets because of coagulation disorders caused by renal diseases. With a better understanding of platelets, it has been found that these anucleate and abundant blood cells not only play a role in hemostasis, but also have important functions in inflammation and immunity. Platelets are not only affected by kidney disease, but may also contribute to kidney disease progression by mediating inflammation and immune effects. This review summarizes the current evidence regarding platelet abnormalities in renal disease, and the multiple effects of platelets on kidney disease progression. The relationship between platelets and kidney disease is still being explored, and further research can provide mechanistic insights into the relationship between thrombosis, bleeding, and inflammation related to kidney disease, and elucidate targeted therapies for patients with kidney disease.

Monitoring Renal Function in HIV Patients Without Kidney Disease Using Endothelial Biomarkers: A Prospective Pilot Study

This study aimed to investigate the association between novel biomarkers and renal injury in people with HIV (PWH). A cohort study was carried out with PWH under chronic use of antiretroviral therapy (ART), followed at a public outpatient service. Clinical and laboratory parameters of the patients were evaluated year by year, from 2015 [at baseline (year 1, Y1)] to 2019 [year 5 (Y5)]. At baseline, biomarkers of renal damage (e.g., neutrophil gelatinase-associated lipocalin-NGAL, monocyte chemoattractant protein-1-MCP-1, and kidney injury molecule-1-KIM-1) and endothelial activation or glycocalyx damage [e.g., intercellular adhesion molecule 1 (ICAM-1), E-selectin, and syndecan-1] were quantified using enzyme-linked immunosorbent assays and their levels were used to classify patients into different groups. However, only syndecan-1 showed a significant correlation with serum creatinine (p < .001) and glomerular filtration rate (GFR) (p = .003) over the years. Moreover, both serum creatinine and GFR in almost 5 years were significantly associated with serum levels of syndecan-1 at baseline. The multivariate linear regression with confounders showed a significant and independent association between GFR and levels of syndecan-1 and CD4 cell count in the beginning of the study, as well as age in Y5. The data reinforce the screening for kidney diseases with novel biomarkers, especially syndecan-1, as an important strategy for a timely diagnostic and therapeutic approach.

Impact of Angiopoietin-2 on Kidney Diseases

Background

Angiopoietins (Ang) are essential angiogenic factors involved in angiogenesis, vascular maturation, and inflammation. The most studied angiopoietins, angiopoietin-1 (Ang-1) and angiopoietin-2 (Ang-2), behave antagonistically to each other in vivo to sustain vascular endothelium homeostasis. While Ang-1 typically acts as the endothelium-protective mediator, its context-dependent antagonist Ang-2 can promote endothelium permeability and vascular destabilization, hence contributing to a poor outcome in vascular diseases via endothelial injury, vascular dysfunction, and microinflammation. The pathogenesis of kidney diseases is associated with endothelial dysfunction and chronic inflammation in renal diseases.

Summary

Several preclinical studies report overexpression of Ang-2 in renal tissues of certain kidney disease models; additionally, clinical studies show increased levels of circulating Ang-2 in the course of chronic kidney disease, implying that Ang-2 may serve as a useful biomarker in these patients. However, the exact mechanisms of Ang-2 action in renal diseases remain unclear.

Key Messages

We summarized the recent findings on Ang-2 in kidney diseases, including preclinical studies and clinical studies, aiming to provide a systematic understanding of the role of Ang-2 in these diseases.

A potential link between fibroblast growth factor-23 and the progression of AKI to CKD

BACKGROUND

Patients who recover from acute kidney injury (AKI) have a 25% increase in the risk of chronic kidney disease (CKD) and a 50% increase in mortality after a follow-up of approximately 10 years. Circulating FGF-23 increases significantly early in the development of AKI, is significantly elevated in patients with CKD and has become a major biomarker of poor clinical prognosis in CKD. However, the potential link between fibroblast growth factor-23 levels and the progression of AKI to CKD remains unclear.

METHOD

Serum FGF-23 levels in AKI patients and ischaemia‒reperfusion injury (IRI) mice were detected with ELISA. Cultured HK2 cells were incubated with FGF-23 and PD173074, a blocker of FGFR, and then TGFβ/Smad and Wnt/β-catenin were examined with immunofluorescence and immunoblotting. Quantitative real-time polymerase chain reaction was used to detect the expression of COL1A1 and COL4A1. Histologic staining confirmed renal fibrosis.

RESULTS

The level of serum FGF-23 was significantly different between AKI patients and healthy controls (P < 0.01). Moreover, serum FGF-23 levels in the CKD progression group were significantly higher than those in the non-CKD progression group of AKI patients (P < 0.01). In the AKI-CKD mouse model, serum FGF-23 levels were increased, and renal fibrosis occurred; moreover, the protein expression of β-catenin and p-Smad3 was upregulated. PD173074 downregulated the expression of β-catenin and p-Smad3 and reduced fibrosis in both mice and HK2 cells.

CONCLUSION

The increase in FGF-23 may be associated with the progression of AKI to CKD and may mediate renal fibrosis via TGF-β and Wnt/β-catenin activation.

Endocrinological disorders in acute kidney injury: an often overlooked field of clinical research

Acute kidney injury (AKI) is a common comorbidity, affecting approximately one in five hospitalized adults. The kidney is the site for the production, metabolism or excretion of most hormones, including the production of erythropoietin (EPO), the active form of vitamin D, renin, thrombopoietin, and the excretion of insulin, catecholamines, gastrin and many other hormones. Therefore, it is reasonable to say that AKI can have a considerable impact on the endocrine system. Although the effects of AKI on various parameters, including cardiovascular parameters, serum electrolytes and acid-base disorders, neuro-humoral mechanisms and neurological outcomes have been extensively studied, the endocrinological consequences of AKI are understudied. Thyroid dysfunction, mainly euthyroid sick syndrome, hypo/hyperglycemia, bone mineral disorders, changes in EPO and atrial natriuretic peptide (ANP) levels are commonly found in AKI. EPO, thyroxine and ANP administration have been evaluated as potential tools to prevent or treat AKI with varying success, while the effects of AKI on some key hormones, including cortisol and insulin, have never been studied. Aim of this narrative review is to illustrate what is known and what is not known about the endocrinological outcomes of AKI. Few clinical trials are ongoing: however, there is a clear need for large-scale randomized controlled trials investigating the endocrinological consequences of AKI.

Circulating Fibroblast Growth Factor-23 Levels Can Predict Rapid Kidney Function Decline in a Healthy Population: A Community-Based Study

BACKGROUND

Fibroblast growth factor-23 (FGF-23) associates with decreased kidney function in patients with chronic kidney disease (CKD). However, the correlation between circulating FGF-23 levels and the rate of renal function decline in healthy individuals is largely unknown. We aimed to evaluate the predictive performance of FGF-23 for rapid kidney function decline (RKFD) in a community-based study.

METHODS

A total of 2963 people residing in northern Taiwan were enrolled from August 2013 to May 2018 for an annual assessment of kidney function for five years. The baseline estimated glomerular filtration rates (eGFR) were calculated using the 2009 and 2021 Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, which aggregates the values of serum creatinine and cystatin C (eGFRcr-cys). The outcome was RKFD-a 15% decrease in estimated glomerular filtration rate (eGFR) within the first four years, and a reduction in eGFR without improvement in the 5th year. A generalized additive model (GAM) was used to determine the cut-off value of FGF-23 to predict RKFD.

RESULTS

The incidence of RKFD was 18.0% (114/634). After matching for age and sex at a 1:1 ratio, a total of 220 subjects were analyzed. eGFRcr-cys was negatively correlated with total vitamin D level but seemed irrelevant to FGF-23. Multivariable logistic regression analysis showed that FGF-23, eGFRcr-cys, and urine albumin-to-creatinine ratio (UACR) were independent predictors of the possibility of RKFD. FGF-23 showed the best predictive performance for RKFD (AUROC: 0.803), followed by baseline eGFRcr-cys (AUROC: 0.639) and UACR (AUROC: 0.591). From the GAM, 32 pg/mL was the most appropriate cut-off value of FGF-23 with which to predict RKFD. The subgroup and sensitivity analyses showed consistent results that high-FGF-23 subjects had higher risks of RKFD.

CONCLUSIONS

Circulating FGF-23 level could be a helpful predictor for RKFD in this community-based population.

Research progress of fibroblast growth factor 23 in acute kidney injury

Fibroblast growth factor 23 (FGF23) is primarily produced in bones and mainly regulates calcium and phosphorus metabolism. The level of circulating FGF23 increases rapidly in the early stage of acute kidney injury (AKI). Recent studies have shown that FGF23 may serve as a biomarker for the diagnosis and poor prognosis of AKI. The mechanism of increased FGF23 in AKI may include increased production of FGF23, decreased renal clearance of FGF23, and some new regulatory factors, such as inflammation and glycerol 3-phosphate. However, the biological effects of elevated FGF23 in AKI are still unclear. It is also not known whether reducing the level of circulating FGF23 could alleviate AKI or its poor prognosis. Here, we review the pathophysiological mechanism and possible regulation of FGF23 in AKI and discuss the possibility of using FGF23 as a therapeutic target.

Lipocalin-2: a novel link between the injured kidney and the bone

PURPOSE OF REVIEW

Fibroblast growth factor 23 (FGF23) excess is associated with left ventricular hypertrophy (LVH) and early mortality in patients with chronic kidney disease (CKD) and in animal models. Elevated Lipocalin-2 (LCN2), produced by the injured kidneys, contributes to CKD progression and might aggravate cardiovascular outcomes. The current review aims to highlight the role of LCN2 in CKD, particularly its interactions with FGF23.

RECENT FINDINGS

Inflammation, disordered iron homeostasis and altered metabolic activity are common complications of CKD, and are associated with elevated levels of kidney-produced LCN2 and bone-secreted FGF23. A recent study shows that elevated LCN2 increases FGF23 production, and contributes to cardiac injury in patients and animals with CKD, whereas LCN2 reduction in mice with CKD reduces FGF23, improves cardiovascular outcomes and prolongs lifespan.

SUMMARY

In this manuscript, we discuss the potential pathophysiological functions of LCN2 as a major kidney-bone crosstalk molecule, linking the progressive decline in kidney function to excessive bone FGF23 production. We also review associations of LCN2 with kidney, cardiovascular and bone and mineral alterations. We conclude that the presented data support the design of novel therapeutic approaches to improve outcomes in CKD.

Endothelial biomarkers as predictors for hemodialysis need in severe leptospirosis patients (Weil's disease)

OBJECTIVE

To investigate the prediction ability of vascular injury biomarkers for hemodialysis requirement in patients with severe leptospirosis.

METHODS

Prospective study with severe leptospirosis patients hospitalized in Fortaleza, Brazil. Blood samples were collected at hospital admission to quantify vascular injury biomarkers: syndecan-1, ICAM-1, VCAM-1, angiopoietin-2 and FGF-23. Two groups were evaluated according to hemodialysis requirement during hospital stay.

RESULTS

27 patients were included, with a mean age of 39 ± 18 years. 88.9% were males. 53.8% needed hemodialysis and presented higher levels of syndecan-1 (572 [300-811] vs. 263 [106-421] ng/mL; p = 0.03), angiopoietin-2 (1.52 [0.72-2.72] vs. 0.63 [0.4-1.38] ng/mL; p = 0.01), and FGF-23 (291 [56-2,031] vs. 10 [10-806] pg/mL; p = 0.021). Syndecan-1 showed significant correlation with creatinine (r = 0.546; p = 0.05) and total bilirubin levels (r = 0.534; p = 0.013) at hospital admission. Angiopoietin-2 showed significant correlation with creatinine levels (r = 0.513; p = 0.009) at hospital admission and the number of hemodialysis sessions (r = 0.406; p = 0.049). No significant correlation was found with FGF-23. Regarding prognostic performance, combined syndecan-1 and angiopoietin-2 levels had a better ability to predict hemodialysis need in patients with severe leptospirosis (AUC-ROC= 0.744 [CI 95%: 0.545 - 0.943] p=0.035).

CONCLUSION

Syndecan-1 and angiopoietin-2 were associated with hemodialysis need in patients with severe leptospirosis and may be useful to improve therapeutic approach and reduce mortality.

The Role and Therapeutic Value of Syndecan-1 in Cancer Metastasis and Drug Resistance

Metastasis and relapse are major causes of cancer-related fatalities. The elucidation of relevant pathomechanisms and adoption of appropriate countermeasures are thus crucial for the development of clinical strategies that inhibit malignancy progression as well as metastasis. An integral component of the extracellular matrix, the type 1 transmembrane glycoprotein syndecan-1 (SDC-1) binds cytokines and growth factors involved in tumor microenvironment modulation. Alterations in its localization have been implicated in both cancer metastasis and drug resistance. In this review, available data regarding the structural characteristics, shedding process, and nuclear translocation of SDC-1 are detailed with the aim of highlighting strategies directly targeting SDC-1 as well as SDC-1-mediated carcinogenesis.

Use of non-conventional biomarkers in the early diagnosis of acute kidney injury in preterm newborns with sepsis

Acute kidney injury (AKI) is a common finding in Neotatal Intensive Care Units (NICU). Sepsis is one the main causes of AKI in preterm newborns. AKI has been associated with significant death rates. Early detection of the condition is the first step to improving prevention, treatment, and outcomes, while decreasing length of hospitalization, care costs, and morbimortality. AKI may progress to chronic kidney disease (CKD), a condition linked with dialysis and greater risk of cardiovascular disease. This review article aims to discuss cases of AKI in preterm newborns with sepsis, the use of biomarkers in lab workup, and the use of non-conventional biomarkers for the early identification of AKI.

Endothelial activation is associated with albuminuria in multibacillary leprosy

Leprosy may present kidney and endothelial abnormalities, being a risk factor for complications. However, the involvement of renal and vascular endothelia has been poorly investigated. We aimed to investigate if the levels of systemic endothelial biomarkers are associated with kidney abnormalities and the clinical forms of leprosy. This is a cross-sectional study with leprosy patients enrolled in January 2017 to December 2018, before the initiation of the multidrug therapy. Leprosy-associated clinical and epidemiological data were collected. Two groups were investigated: Paucibacillary (PB) and Multibacillary (MB) infections, for the comparisons. Serum and urine samples were obtained for laboratory analysis. In serum samples, were evaluated the endothelial biomarkers VCAM-1 and ICAM-1. In total, 101 leprosy patients were included, the mean age was 48±١٥ years and 71 (70%) were male. The multibacillary form occurred in 81 cases (80%), among which 22 had the Virchowian form. Serum creatinine was more elevated in the MB group than in PB patients. In addition, VCAM-1 was elevated in the MB group and was correlated with the bacteriological index (rho = 0.372, p <0.01), the duration of disease symptoms (rho = 0.234, p = 0.04), and the number of skin lesions (rho = 0.468, p <0.001). Moreover, in MB patients who presented albuminuria >15 mg/g of creatinine, VCAM-1 showed a significant correlation with increased albuminuria and improved the correlation with the number of skin lesions (rho= 0.563, p=0.010). In conclusion, higher systemic VCAM-1 levels were associated with the multibacillary clinical form of leprosy and with increased albuminuria. Prospective studies are necessary to establish a cause-effect and evaluate the preventive role of these biomarkers to improve the clinical care.

Human glycocalyx shedding: Systematic review and critical appraisal

BACKGROUND

The number of studies measuring breakdown products of the glycocalyx in plasma has increased rapidly during the past decade. The purpose of the present systematic review was to assess the current knowledge concerning the association between plasma concentrations of glycocalyx components and structural assessment of the endothelium.

METHODS

We performed a literature review of Pubmed to determine which glycocalyx components change in a wide variety of human diseases and conditions. We also searched for evidence of a relationship between plasma concentrations and the thickness of the endothelial glycocalyx layer as obtained by imaging methods.

RESULTS

Out of 3,454 publications, we identified 228 that met our inclusion criteria. The vast majority demonstrate an increase in plasma glycocalyx products. Sepsis and trauma are most frequently studied, and comprise approximately 40 publications. They usually report 3-4-foldt increased levels of glycocalyx degradation products, most commonly of syndecan-1. Surgery shows a variable picture. Cardiac surgery and transplantations are most likely to involve elevations of glycocalyx degradation products. Structural assessment using imaging methods show thinning of the endothelial glycocalyx layer in cardiovascular conditions and during major surgery, but thinning does not always correlate with the plasma concentrations of glycocalyx products. The few structural assessments performed do not currently support that capillary permeability is increased when the plasma levels of glycocalyx fragments in plasma are increased.

CONCLUSIONS

Shedding of glycocalyx components is a ubiquitous process that occurs during both acute and chronic inflammation with no sensitivity or specificity for a specific disease or condition.