A translational approach to micro-inflammation in end-stage renal disease: molecular effects of low levels of interleukin-6

Methacrylated chitosan/jellyfish collagen membranes as cell instructive platforms for liver tissue engineering

Although the multidisciplinary area of liver tissue engineering is in continuous progress, research in this field is still focused on developing an ideal liver tissue template. Innovative strategies are required to improve membrane stability and bioactivity. In our study, sustainable biomimetic membranes were developed by blending methacrylated chitosan (CSMA) with jellyfish collagen (jCol) for liver tissue engineering applications. The in vitro biological behaviour demonstrated the capability of the developed membranes to create a suitable milieu to enable hepatocyte growth and differentiation. The functionalization of chitosan together with the biocompatibility of marine collagen and the intrinsic membrane properties offered the ideal biochemical, topographical, and mechanical cues to the cells. Thanks to the enhanced CSMA/jCol membranes' characteristics, hepatocytes on such biomaterials exhibited improved growth, viability, and active liver-specific functions when compared to the cell fate achieved on CSMA membranes. Our study provides new insights about the influence of membrane properties on liver cells behaviour for the design of novel instructive biomaterials. The enrichment of functionalized chitosan with marine collagen represents a promising and innovative approach for the development of an appropriate platform for hepatic tissue engineering.

Hollow Fiber and Nanofiber Membranes in Bioartificial Liver and Neuronal Tissue Engineering

To date, the creation of biomimetic devices for the regeneration and repair of injured or diseased tissues and organs remains a crucial challenge in tissue engineering. Membrane technology offers advanced approaches to realize multifunctional tools with permissive environments well-controlled at molecular level for the development of functional tissues and organs. Membranes in fiber configuration with precisely controlled, tunable topography, and physical, biochemical, and mechanical cues, can direct and control the function of different kinds of cells toward the recovery from disorders and injuries. At the same time, fiber tools also provide the potential to model diseases in vitro for investigating specific biological phenomena as well as for drug testing. The purpose of this review is to present an overview of the literature concerning the development of hollow fibers and electrospun fiber membranes used in bioartificial organs, tissue engineered constructs, and in vitro bioreactors. With the aim to highlight the main biomedical applications of fiber-based systems, the first part reviews the fibers for bioartificial liver and liver tissue engineering with special attention to their multifunctional role in the long-term maintenance of specific liver functions and in driving hepatocyte differentiation. The second part reports the fiber-based systems used for neuronal tissue applications including advanced approaches for the creation of novel nerve conduits and in vitro models of brain tissue. Besides presenting recent advances and achievements, this work also delineates existing limitations and highlights emerging possibilities and future prospects in this field.

Vascular Calcification-New Insights Into Its Mechanism

Vascular calcification (VC), which is categorized by intimal and medial calcification, depending on the site(s) involved within the vessel, is closely related to cardiovascular disease. Specifically, medial calcification is prevalent in certain medical situations, including chronic kidney disease and diabetes. The past few decades have seen extensive research into VC, revealing that the mechanism of VC is not merely a consequence of a high-phosphorous and -calcium milieu, but also occurs via delicate and well-organized biologic processes, including an imbalance between osteochondrogenic signaling and anticalcific events. In addition to traditionally established osteogenic signaling, dysfunctional calcium homeostasis is prerequisite in the development of VC. Moreover, loss of defensive mechanisms, by microorganelle dysfunction, including hyper-fragmented mitochondria, mitochondrial oxidative stress, defective autophagy or mitophagy, and endoplasmic reticulum (ER) stress, may all contribute to VC. To facilitate the understanding of vascular calcification, across any number of bioscientific disciplines, we provide this review of a detailed updated molecular mechanism of VC. This encompasses a vascular smooth muscle phenotypic of osteogenic differentiation, and multiple signaling pathways of VC induction, including the roles of inflammation and cellular microorganelle genesis.

Oral supplementation with omega-3 fatty acids and inflammation markers in patients with chronic kidney disease in hemodialysis

Chronic kidney disease (CKD) is an increasingly common public health problem that increases the risk of death because of cardiovascular complications by 2-3 times compared with the general population. This research concerns a prospective, randomized, double-blind study in patients with CKD undergoing hemodialysis. The participants were assigned to 1 of 2 groups: the study group (group A; 46 patients) received 4 capsules (2.4 g) of omega-3 fatty acids daily during the 12-week intervention, while patients in the control group (group B; 47 patients) received 4 capsules of paraffin oil. The patients' general characteristics, nutritional indicators, renal disease markers and inflammatory markers (C-reactive protein, interleukin (IL)-6, IL-10, and tumour necrosis factor alpha (TNF-α)) were evaluated. No differences were found between the general characteristics of the patients (P < 0.05), and no differences were shown in the nutritional indicators and markers of kidney disease (P < 0.05). Patients in group A showed significant decreases in levels of C-reactive protein, IL-6, TNF-α, and the IL-10/IL-6 ratio after 12 weeks of supplementation (P < 0.05). Patients in group B did not show any significant changes in concentrations of inflammatory markers during the intervention (P < 0.05). In conclusion, oral supplementation with omega-3 fatty acids produces a significant decrease in the concentrations of inflammation markers in patients with chronic kidney disease on hemodialysis. Novelty Oral supplementation with omega-3 fatty acids produced significant decreases in the concentrations of inflammation markers. This supplementation could be given to patients with uremic syndrome and coronary heart disease to reduce cardiovascular risk.

Effects of Omega-3 Fatty Acids on Markers of Inflammation in Patients With Chronic Kidney Disease: A Controversial Issue

Chronic kidney disease (CKD) is a global problem which contributes to a significant morbidity and mortality in China. Concomitant inflammatory state further boosts the mortality due to cardiovascular events in patients with CKD undergoing dialysis. There is a general notion that Omega-3 fatty acids including docosahexaenoic acids (DHA) and eicosapentaenoic (EPA) have certain health benefits perhaps via the regulation of inflammation. However, the anti-inflammatory effect of omega-3 fatty acids in patients with CKD is controversial. We analyzed the data of oral supplementation of omega-3 fatty acids in CKD patients by searching literature on database from inception to August 2016. The analysis included randomized controlled trials (RCTs) derived from multiple databases, and the effect of omega-3 fatty acids supplementation versus the control cohorts were compared. All of the data analysis was calculated by RevMan 5.2. A total of 12 RCTs involving 487 patients were included in the meta-analysis. Among them 254 patients received omega-3 fatty acids and 233 patients served as controls who received placebo. The meta-analysis revealed no statistical significance in serum levels of C-reactive protein (CRP) (SMD, -0.20; 95% CI, -0.44 to 0.05; P = 0.11), IL-6 (SMD, 0.00; 95% CI, -0.33 to 0.33; P = 0.99) and TNF-α (SMD, 0.14; 95% CI, -0.17 to 0.44; P = 0.38) between the omega-3 fatty acids supplementation group and control. This suggested that there is insufficient evidence to conclude the benefit of omega-3 fatty acids oral supplementation in reducing serum levels of CRP, IL-6 and TNF-α in patients with CKD.

Simulated microgravity decreases circulating iron in rats: role of inflammation-induced hepcidin upregulation

NEW FINDINGS

What is the central question of this study? Although microgravity is well known to reduce circulating iron in astronauts, the underlying mechanism is still unknown. We investigated whether hepcidin, a key hormone regulating iron metabolism, could be involved in this deleterious effect. What is the main finding and its importance? We show that hindlimb suspension, a model of microgravity, stimulates the production of hepcidin in liver of rats. In agreement with the biological role of hepcidin, we found a decrease of circulating iron and an increase of spleen iron content in hindlimb-unloaded rats. Consequently, our study supports the idea that hepcidin could play a role in the alteration of iron metabolism parameters observed during spaceflight. During spaceflight, humans exposed to microgravity exhibit an increase of iron storage and a reduction of circulating iron. Such perturbations could promote oxidative stress and anaemia in astronauts. The mechanism by which microgravity modulates iron metabolism is still unknown. Herein, we hypothesized that microgravity upregulates hepcidin, a hormone produced by the liver that is the main controller of iron homeostasis. To test this hypothesis, rats were submitted to hindlimb unloading (HU), the reference model to mimic the effects of microgravity in rodents. After 7 days, the mRNA level of hepcidin was increased in the liver of HU rats (+74%, P = 0.001). In agreement with the biological role of hepcidin, we found an increase of spleen iron content (+78%, P = 0.030) and a decrease of serum iron concentration (-35%, P = 0.002) and transferrin saturation (-25%, P = 0.011) in HU rats. These findings support a role of hepcidin in microgravity-induced iron metabolism alteration. Furthermore, among the signalling pathways inducing hepcidin mRNA expression, we found that only the interleukin-6/signal transducer and activator of transcription 3 (IL-6/STAT3) axis was activated by HU, as shown by the increase of phospho-STAT3 (+193%, P < 0.001) and of the hepatic mRNA level of haptoglobin (+167%, P < 0.001), a STAT3-inducible gene, in HU rats. Taken together, these data support the idea that microgravity may alter iron metabolism through an inflammatory process upregulating hepcidin.

Efficacy comparison of atorvastatin versus rosuvastatin on blood lipid and microinflammatory state in maintenance hemodialysis patients

Introduction: To investigate the effect of Atorvastatin (ATO) and Rosuvastatin (ROS) on blood lipid, high sensitivity CRP (hs-CRP), interleukin-6 (IL-6), albumin (ALB), prealbumin (PA), and transferring (TF) in maintenance hemodialysis (MHD) patients.

Methods: Eighty MHD patients were enrolled and divided into two groups: ROS and ATO. Patients in Group ROS (n = 38) received ROS (10 mg/day), and those in group ATO (n = 42) received ATO (20 mg/day) for 12 weeks, respectively.

Findings: Administration of ROS and ATO both significantly reduced the concentrations of TC, LDL-C, TG, hs-CRP, and IL-6, but increased high-density lipoproteincholesterol (HDL-C), ALB, PA, and TF levels. Furthermore, the level of LDL-C decreased more significantly with inhibited microinflammation and improved nutrition situation in ROS group compared with ATO group. ATO and ROS not only decreased blood lipid levels but also inhibited the microinflammatory state and improved nutrition situation in MHD patients.

Discussion: The results have shown that ROS is better than ATO in the treatment of MHD patients.

Laboratory use of hepcidin in renal transplant recipients

Hepcidin is a small peptide with a critical role in cellular iron homeostasis, as it regulates utilization of stored iron and antimicrobial defense in inflammation (bacterial and fungal). Since it was isolated in 2000, and especially in the last decade, numerous studies aimed to evaluate the clinical use of plasma and urine hepcidin as a marker of anemia, especially anemia of chronic disease and post-transplant anemia (PTA). Hepcidin regulation is delicately tuned by two inflammatory pathways activated by interleukin-6 (IL-6) and bone morphogenic proteins (BMPs) and iron regulated pathway sensitive to circulating transferin-iron (TR-Fe) complex. BMP-mediated pathway and TR-Fe sensitive pathway seem to be connected by hemojuveline, a BMP co-factor that interacts with transferine receptor 2 (TRF2) in cases of high TR-Fe circulatory concentration. In addition to these regulatory mechanisms other regulators and signaling pathways are being extensively researched.
Hepcidin has been identified as an important contributor to morbidity and mortality in end stage renal disease (ESRD) but no such association has jet been found in case of PTA. However, there is an association between higher doses of erythropoiesis-stimulating agents (ESA) and mortality in the posttransplant period and the assumption that hepcidin might play a role in ESA resistance in PTA. Thus the review’s main goal was to summarize papers published on the association of hepcidin with PTA, give up-to-date information on hepcidin regulation and on potential therapeutics that optimize hepcidin regulation. We also compared the performances of tests for hepcidin determination and reviewed research on immunosuppressants’ (IS) effect on hepcidin concentration.

Vascular Calcification in Uremia: New-Age Concepts about an Old-Age Problem

A hallmark of aging, and major contributor to the increased prevalence of cardiovascular disease in patients with chronic kidney disease (CKD), is the progressive structural and functional deterioration of the arteries and concomitant accrual of mineral. Vascular calcification (VC) was long viewed as a degenerative age-related pathology that resulted from the passive deposition of mineral in the extracellular matrix; however, since the discovery of "bone-related" protein expression in calcified atherosclerotic plaques over 20 years ago, a plethora of studies have evoked the now widely accepted view that VC is a highly regulated and principally cell-mediated phenomenon that recapitulates many features of physiologic ossification. Central to this theory are changes in vascular smooth muscle cell (VSMC) phenotype and viability, thought to be driven by chronic exposure to a number of dystrophic stimuli characteristics of the uremic state. Here, dedifferentiated synthetic VSMCs are seen to spawn calcifying matrix vesicles that actively seed mineralization of the arterial matrix. This review provides an overview of the major epidemiological, histological, and molecular aspects of VC in the context of CKD, and a counterpoint to the prevailing paradigm that emphasizes the primacy of VSMC-mediated mechanisms. Particular focus is given to the import of protein and small molecule inhibitors in regulating physiologic and pathological mineralization and the emerging role of mineral nanoparticles and their interplay with proinflammatory processes.

Evidence that p-cresol and IL-6 are adsorbed by the HFR cartridge: towards a new strategy to decrease systemic inflammation in dialyzed patients?

Introduction

Hemodialysis (HD) and hemodiafiltration clear only with a low efficiency the plasma from interleukin-6 and p-cresol, two protein-bound uremic toxins associated with high cardiovascular risk in end stage renal disease. HFR Supra is a double-chamber hemodiafiltration system in which the ultrafiltrate returns to the patient after its regeneration through a resin cartridge that binds hydrophobic and protein-bound solutes. In the present study, we evaluated whether the HFR cartridge can also bind total p-cresol and IL-6 and remove them from the ultrafiltrate.

Methods

We compared the levels of IL-6 and p-cresol in ultrafiltrate samples collected at the inlet (UF_in) and at the outlet (UF_out) of the cartridge at the start or at the end of a 240 min HFR session in 12 inflamed chronic HD patients. The pro-inflammatory activity of the ultrafiltrate samples was also determined by evaluating the changes that they induced in IL-6 mRNA expression and protein release in peripheral blood mononuclear cells from 12 healthy volunteers. IL-6 and p-cresol circulating levels were also assessed in peripheral plasma blood samples collected before and after HFR and, for comparison, a control HD.

Results

p-Cresol and IL-6 were lower in UF_out than in UF_in both at the start and at the end of the HFR session, suggesting that they were retained by the cartridge. IL-6 mRNA expression and release were lower in PBMC incubated with UF_out collected at the end than with UF_in collected at the start of HFR, suggesting that passage through the cartridge reduced UF pro-inflammatory activity. Plasma total p-cresol decreased by about 53% after HFR, and 37% after HD. IL-6 circulating values were unmodified by either these dialysis procedures.

Conclusions

This study shows that the HFR-Supra cartridge retains total p-cresol and IL-6 in the ultrafiltrate and lowers plasma total p cresol but not IL-6 levels.

Trial Registration

ClinicalTrials.gov NCT01865773

Correlation between the microinflammatory state and left ventricular structural and functional changes in maintenance haemodialysis patients

The aim of this study was to examine the correlation between the microinflammatory state and structural and functional changes of the left ventricle in maintenance haemodialysis patients (MHD). In total, 48 MHD patients and 30 healthy volunteers participated in this study. The microinflammatory state was detected from high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α) levels determined by ELISA. The structure and function of the left ventricle was measured according to ultrasound cardiogram examination. The serum levels of hs-CRP, IL-6 and TNF-α in the MHD patients were higher compared with those in the controls (P<0.05). Furthermore, the measurements of the left atrial diameter (LAD), left venticular diameter (LVD), interventricular septal thickness (IVST), left ventricular posterior wall thickness (LVPWT) and the left ventricular mass index (LVMI) increased significantly and the left ventricular function (LVEF) was reduced. Correlation analysis demonstrated that the concentrations of hs-CRP, TNF-α and IL-6 correlated with the LVMI (P<0.05), but only hs-CRP correlated with the loss of function of the heart in the haemodialysis patients (P<0.05). The microinflammatory state may be closely associated with the structural and functional impairment of the heart in MHD patients.

Iron status, inflammation and hepcidin in ESRD patients: The confounding role of intravenous iron therapy

Uremia is a state of heightened inflammatory activation. This might have an impact on several parameters including anemia management. Inflammation interferes with iron utilization in chronic kidney disease through hepcidin. We studied the body iron stores, degree of inflammatory activation, and pro-hepcidin levels in newly diagnosed patients with end-stage renal disease (ESRD), and compared them with normal population. In addition to clinical examination and anthropometry, the levels of iron, ferritin, C-reactive protein, tumor necrosis factor alfa, interleukin-6, and prohepcidin were estimated. A total of 74 ESRD patients and 52 healthy controls were studied. The ESRD patients had a significantly lower estimated body fat percentage, muscle mass, and albumin; and higher transferrin saturation (TSAT) and raised serum ferritin. Inflammatory activation was evident in the ESRD group as shown by the significantly higher CRP, IL-6, and TNF-α levels. The pro-hepcidin levels were also increased in this group. Half of the ESRD patients had received parenteral iron before referral. Patients who had received intravenous iron showed higher iron, ferritin, and TSAT levels. These patients also showed more marked inflammatory activation, as shown by the significantly higher CRP, TNF-α, and IL-6 levels. We conclude that our ESRD patients showed marked inflammatory activation, which was more pronounced in patients who had received IV iron. High hepcidin levels could explain the functional iron deficiency. The cause of the relatively greater degree of inflammatory activation as well as the relationship with IV iron administration needs further studies.