Haptoglobin reduces renal oxidative DNA and tissue damage during phenylhydrazine-induced hemolysis

Nrf2 protects against oxidative damage induced by hemoglobin in the liver of grass carp (Ctenopharyngodon idella)

Hemoglobin (Hb) releases during hemorrhaging and causes oxidative damage, further exacerbates the development of multiple diseases. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor that regulates cellular defenses against toxic and oxidative challenges. However, the regulation mechanism of Nrf2 in Hb-induced oxidative stress remains unclear in teleost. To accomplish this goal, a hemolysis model was established by injecting grass carp with phenylalanine (PHZ), and the immunofluorescence analysis (IFA) and hematoxylin and eosin (H&E) staining revealed that PHZ-induced hemolysis caused Hb accumulation and hepatic vacuolization, resulted in tissue damage. Prussian blue, Sirius red, and Masson staining results revealed significant iron deposition and extensive collagen fiber accumulation in the liver. IFA and immunohistochemical analyses demonstrated that PHZ-induced hemolysis markedly increased the production of reactive oxygen species (ROS), malondialdehyde (MDA), and 4-hydroxynonenal (4-HNE). The quantitative real-time PCR (qRT-PCR) analysis data revealed that the PHZ-induced hemolysis also significantly upregulated the expression of antioxidant-related genes through activation of the adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK)/Nrf2 signaling pathway. To further explore the molecule regulation mechanism of PHZ-induced hemolysis, the RNA-seq analysis was performed, and the data revealed that the AMPK/Nrf2 and multiple programmed cell death pathways, including ferroptosis, autophagy, apoptosis, and necroptosis in PHZ injection groups were significant upregulated. In vitro, the hemin supplementation activated the expression of target genes in the AMPK/Nrf2 pathway detected by qRT-PCR. To further verify the regulation function of Nrf2, an Nrf2 activator (4OI) was supplemented, and the flow cytometer analysis results suggested that the Hb-induced cell damage was significantly attenuated. However, the supplementary of ML385 down-regulated the AMPK/Nrf2 pathway and aggravated the hemin induced cell death. In conclusion, these findings highlight the critical regulatory role of the AMPK/Nrf2 signaling pathway in protecting against Hb-induced oxidative damage in the liver of grass carp.

Urinary biomarkers for active Lupus Nephritis that have survived independent validation across cohorts

Most reported biomarkers for lupus nephritis (LN) have not been independently validated across cohorts. Moreover, many of the documented biomarker candidates have been reported to be elevated in LN compared to healthy controls. However, biomarkers that distinguish patients with active LN (ALN) from inactive systemic lupus erythematosus (iSLE) hold significant clinical utility. Hence, our review attempts to identify urine protein biomarkers for LN that have been independently validated across two or more cohorts and exhibit good diagnostic potential for distinguishing ALN from iSLE. PubMed and OVID were screened for studies assessing the diagnostic value of urinary biomarkers in patients with ALN compared to iSLE. Forty peer-reviewed articles were evaluated, encompassing urine biomarker data from 3,411 distinct patients. Of the 32 candidate biomarkers identified, fourteen were repeatedly reported/tested in four or more papers each, namely ALCAM, CCL2 (MCP1), CD163, HAVCR1 (KIM-1), HPGDS, ICAM-1 (CD54), ICAM-2 (CD102), IGFBP-2, LCN2, NCAM-1 (CD56), SELE (E-Selectin), SELL (L-Selectin), TNFSF12 (TWEAK), and VCAM-1, with most exhibiting C-statistics of 0.80 or more across multiple studies when discriminating patients with ALN from iSLE. The 32 reproducibly elevated biomarkers for active LN mapped to nine functional categories. The urinary proteins reported here promise to serve as a liquid biopsy for ALN. Besides representing potential candidates for diagnostic, monitoring, predictive, and prognostic biomarkers in LN, they also provide a window into potential molecular processes within the kidney that may be driving LN. Thus, ongoing advances in proteomics, which offer wider proteome coverage at increased sensitivity, are likely to further reshape our perspective of urinary biomarkers for LN.

Megalin-related mechanism of hemolysis-induced acute kidney injury and the therapeutic strategy

Hemolysis-induced acute kidney injury (AKI) is attributed to heme-mediated proximal tubule epithelial cell (PTEC) injury and tubular cast formation due to intratubular protein condensation. Megalin is a multiligand endocytic receptor for proteins, peptides, and drugs in PTECs and mediates the uptake of free hemoglobin and the heme-scavenging protein α1-microglobulin. However, understanding of how megalin is involved in the development of hemolysis-induced AKI remains elusive. Here, we investigated the megalin-related pathogenesis of hemolysis-induced AKI and a therapeutic strategy using cilastatin, a megalin blocker. A phenylhydrazine-induced hemolysis model developed in kidney-specific mosaic megalin knockout (MegKO) mice confirmed megalin-dependent PTEC injury revealed by the co-expression of kidney injury molecule-1 (KIM-1). In the hemolysis model in kidney-specific conditional MegKO mice, the uptake of hemoglobin and α1-microglobulin as well as KIM-1 expression in PTECs was suppressed, but tubular cast formation was augmented, likely due to the nonselective inhibition of protein reabsorption in PTECs. Quartz crystal microbalance analysis revealed that cilastatin suppressed the binding of megalin with hemoglobin and α1-microglobulin. Cilastatin also inhibited the specific uptake of fluorescent hemoglobin by megalin-expressing rat yolk sac tumor-derived L2 cells. In a mouse model of hemolysis-induced AKI, repeated cilastatin administration suppressed PTEC injury by inhibiting the uptake of hemoglobin and α1-microglobulin and also prevented cast formation. Hemopexin, another heme-scavenging protein, was also found to be a novel ligand of megalin, and its binding to megalin and uptake by PTECs in the hemolysis model were suppressed by cilastatin. Mass spectrometry-based semiquantitative analysis of urinary proteins in cilastatin-treated C57BL/6J mice indicated that cilastatin suppressed the reabsorption of a limited number of megalin ligands in PTECs, including α1-microglobulin and hemopexin. Collectively, cilastatin-mediated selective megalin blockade is an effective therapeutic strategy to prevent both heme-mediated PTEC injury and cast formation in hemolysis-induced AKI. © 2024 The Pathological Society of Great Britain and Ireland.

Mechanisms of persistent hemolysis-induced middle kidney injury in grass carp (Ctenopharyngodon idella)

Infection-induced hemolysis results in intravascular hemolysis, which releases hemoglobin (Hb) into the tissues. Free Hb exhibits cytotoxic, oxidative, and pro-inflammatory effects, leading to systemic inflammation, vascular constriction dysfunction, thrombosis, and proliferative vascular lesions. Currently, the impact of intravascular hemolysis on the middle kidney in fish is unclear. Here, the injection of phenylhydrazine (PHZ) was used to establish a persistent hemolysis model in grass carp. The determination results revealed that the PHZ-induced hemolysis caused conspicuous tissue damage in the kidneys of grass carp, increased the levels of Cr in the serum and the expression indicators of kidney injury-related genes in the middle kidney. Prussian blue staining indicated that PHZ-induced hemolysis significantly increased the deposition of iron ions in the kidneys of grass carp, and activated the expression levels of iron metabolism-related genes. The results of oxidative damage-related experiments indicate that under PHZ treatment, the activity of middle kidney cells decreases, and the production of oxidative damage markers malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) increases, simultaneously inhibiting the activity of antioxidant enzymes and upregulating the transcription levels of antioxidant enzyme-related genes. Additionally, the analysis of inflammatory factors revealed a significant upregulation of genes associated with inflammation induced by PHZ-induced hemolysis. The transcriptome analysis was performed to further explore the molecular regulatory effects of hemolysis on tissues, the analysis revealed the treatment of PHZ activated various of programmed cell death (PCD) pathways, including ferroptosis, apoptosis, and autophagy. In summary, this study found that sustained hemolysis in fish results in Hb and iron ion deposition in middle kidney, promoting oxidative damage, ultimately inducing various forms of PCD.

Exploring the role of antioxidants in sepsis-associated oxidative stress: a comprehensive review

Sepsis is a potentially fatal condition characterized by organ dysfunction caused by an imbalanced immune response to infection. Although an increased inflammatory response significantly contributes to the pathogenesis of sepsis, several molecular mechanisms underlying the progression of sepsis are associated with increased cellular reactive oxygen species (ROS) generation and exhausted antioxidant pathways. This review article provides a comprehensive overview of the involvement of ROS in the pathophysiology of sepsis and the potential application of antioxidants with antimicrobial properties as an adjunct to primary therapies (fluid and antibiotic therapies) against sepsis. This article delves into the advantages and disadvantages associated with the utilization of antioxidants in the therapeutic approach to sepsis, which has been explored in a variety of animal models and clinical trials. While the application of antioxidants has been suggested as a potential therapy to suppress the immune response in cases where an intensified inflammatory reaction occurs, the use of multiple antioxidant agents can be beneficial as they can act additively or synergistically on different pathways, thereby enhancing the antioxidant defense. Furthermore, the utilization of immunoadjuvant therapy, specifically in septic patients displaying immunosuppressive tendencies, represents a promising advancement in sepsis therapy.

Fish waste to sustainable additives: Fish protein hydrolysates alleviate intestinal dysbiosis and muscle atrophy induced by poultry by-product meal in Lates calcarifer juvenile

Valorising waste from the processing of fishery and aquaculture products into functional additives, and subsequent use in aquafeed as supplements could be a novel approach to promoting sustainability in the aquaculture industry. The present study supplemented 10% of various fish protein hydrolysates (FPHs), obtained from the hydrolysis of kingfish (KH), carp (CH) and tuna (TH) waste, with 90% of poultry by-product meal (PBM) protein to replace fishmeal (FM) completely from the barramundi diet. At the end of the trial, intestinal mucosal barriers damage, quantified by villus area (VA), lamina propria area (LPA), LPA ratio, villus length (VL), villus width (VW), and neutral mucin (NM) in barramundi fed a PBM-based diet was repaired when PBM was supplemented with various FPHs (p < 0.05, 0.01, and 0.001). PBM-TH diet further improved these barrier functions in the intestine of fish (p < 0.05 and 0.001). Similarly, FPHs supplementation suppressed PBM-induced intestinal inflammation by controlling the expression of inflammatory cytokines (tnf-α and il-10; p < 0.05 and 0.001) and a mucin-relevant production gene (i-mucin c; p < 0.001). The 16S rRNA data showed that a PBM-based diet resulted in dysbiosis of intestinal bacteria, supported by a lower abundance of microbial diversity (p < 0.001) aligned with a prevalence of Photobacterium. PBM-FPHs restored intestine homeostasis by enhancing microbial diversity compared to those fed a PBM diet (p < 0.001). PBM-TH improved the diversity (p < 0.001) further by elevating the Firmicutes phylum and the Ruminococcus, Faecalibacterium, and Bacteroides genera. Muscle atrophy, evaluated by fiber density, hyperplasia and hypertrophy and associated genes (igf-1, myf5, and myog), occurred in barramundi fed PBM diet but was repaired after supplementation of FPHs with the PBM (p < 0.05, 0.01, and 0.001). Similarly, creatine kinase, calcium, phosphorous, and haptoglobin were impacted by PBM-based diet (p < 0.05) but were restored in barramundi fed FPHs supplemented diets (p < 0.05 and 0.01). Hence, using circular economy principles, functional FPHs could be recovered from the fish waste applied in aquafeed formulations and could prevent PBM-induced intestinal dysbiosis and muscular atrophy.

GRAPHICAL ABSTRACT

Proteomics analysis of chronic skin injuries caused by mustard gas

Sulfur mustard (SM) is an alkylating and forming chemical that was widely used by Iraqi forces during the Iran–Iraq wars. One of the target organs of SM is the skin. Understanding the mechanisms involved in the pathogenesis of SM may help better identify complications and find appropriate treatments. The current study collected ten SM-exposed patients with long-term skin complications and ten healthy individuals. Proteomics experiments were performed using the high-efficiency TMT10X method to evaluate the skin protein profile, and statistical bioinformatics methods were used to identify the differentially expressed proteins. One hundred twenty-nine proteins had different expressions between the two groups. Of these 129 proteins, 94 proteins had increased expression in veterans' skins, while the remaining 35 had decreased expression. The hub genes included RPS15, ACTN1, FLNA, HP, SDHC, and RPL29, and three modules were extracted from the PPI network analysis. Skin SM exposure can lead to oxidative stress, inflammation, apoptosis, and cell proliferation.

Anti-Anemic Effect of Antioxidant-Rich Apple Vinegar against Phenylhydrazine-Induced Hemolytic Anemia in Rats

This study aims to examine the ability of apple vinegar on phenylhydrazine (PHZ)-induced hemolytic anemia in Wistar rats. In vitro, phenolic and flavonoid content and antioxidant activity were determined. In vivo, phenylhydrazine (10 mg/kg) was injected intravenously into rats for 4 days and then treated with apple vinegar daily by gavage (1 mL/kg) for five weeks. high level of polyphenols and flavonoids (90 ± 1.66 mg GAE/100 mL and 7.29 ± 0.23 mg QE/100 mL, respectively) were found in the apple vinegar which gives it a good ability to scavenge free radicals (TAC = 4.22 ± 0.18 mg AAE/100 mL and DPPH, IC₅₀ = 0.49 ± 0.004 µL/ml). The phytochemical composition of apple vinegar revealed the presence of numerous bioactive compounds including arbutin, apigenin, sinapic, ferulic and trans-ferulic acids. The major antioxidant components in apple vinegar were ferulic and trans-ferulic acids (40% and 43%, respectively). PHZ treatment induced changes in platelets, blood cell count, mean corpuscular volume, hemoglobin concentration and mean capsulated hemoglobin. However, the co-administration of apple vinegar revealed its capacity to ameliorate the changes induced by phenylhydrazine. Therefore, apple vinegar use could have a positive impact on the prevention of hemolytic anemia induced by phenylhydrazine due to the antioxidant properties of its major components.

Ficus glumosa Del. reduces phenylhydrazine-induced hemolytic anaemia and hepatic damage in Wistar rats

OBJECTIVES

Anemia is a direct or indirect consequence of oxidative stress via free radicals on erythrocytes and subsequently on other tissues like liver. Ficus glumosa constitute a rich pharmacologically compound that can prevent or repair oxidative damage. Therefore, this study seeks to evaluate the effect of F. glumosa on phenylhydrazine-induced hemolytic anemia and hepatic damage in rats.

METHODS

Twenty-four (24) albino Wistar rats were assigned to four (4) experimental groups (n=6) as follows: Group I (non-anemic control) and Group 2 (anemic control) received normal saline, while Group III and IV (test groups) 200 and 400 mg/kg of aqueous leaf extract of F. glumosa (ALEFG), respectively. All the groups were treated orally (via a cannula) for seven consecutive days. Intraperitoneal (IP) injection of phenylhydrazine (PHZ) at 40 mg/kg for two consecutive days induced hemolytic anemia in group II to IV before treatment. Rats of all groups were anaesthetized and sacrificed 24 h after the last treatment. Blood and liver samples were collected for some hematological indices, liver function test, antioxidant parameter and histological analysis.

RESULTS

The LD₅₀ of ALEFG was assessed orally in rats and found to be above 5,000 mg/kg body weight. Significant (p<0.05) decreases in the level of red blood cell (RBC), hemoglobin (HGB) concentrations and packed cell volume (PCV) by 50% after 2 days of PHZ induction, were attenuated by more than 50% after 7 days administration of ALEFG at 200 and 400 mg/kg. The percentage change in body weight increased significantly (p<0.05) after 7 days post PHZ-induced anemia, but those that received oral administration of ALEFG (at 200 and 400 mg/kg) for 7 days increased significantly (p<0.05) by more than 2%, dose-dependently compared to anemic untreated group. Increased level of serum ALT, AST, ALP and GGT in PHZ-induced anemic animals, were significantly (p<0.05) attenuated in the groups that received oral administration of ALEFG (at 200 and 400 mg/kg) for 7 days. Decreased level of catalase (CAT) and superoxide dismutase (SOD) activities with concomitant increase in malondialdehyde (MDA) content from PHZ-induced untreated group, were significantly (p<0.05) mitigated in the rats that received oral administration of ALEFG (at 200 and 400 mg/kg) for 7 days. Histopathological analysis showed that ALEFG could remarkably though not completely mitigated PHZ-induced hepatic damage.

CONCLUSIONS

Our data suggests that the leaves of F. glumosa contain important antioxidant(s) that could effectively reduce hemolytic anemia and hepatic damage, especially during phenylhydrazine-induced toxicity.

Heme Oxygenase 1: A Defensive Mediator in Kidney Diseases

The incidence of kidney disease is rising, constituting a significant burden on the healthcare system and making identification of new therapeutic targets increasingly urgent. The heme oxygenase (HO) system performs an important function in the regulation of oxidative stress and inflammation and, via these mechanisms, is thought to play a role in the prevention of non-specific injuries following acute renal failure or resulting from chronic kidney disease. The expression of HO-1 is strongly inducible by a wide range of stimuli in the kidney, consequent to the kidney's filtration role which means HO-1 is exposed to a wide range of endogenous and exogenous molecules, and it has been shown to be protective in a variety of nephropathological animal models. Interestingly, the positive effect of HO-1 occurs in both hemolysis- and rhabdomyolysis-dominated diseases, where the kidney is extensively exposed to heme (a major HO-1 inducer), as well as in non-heme-dependent diseases such as hypertension, diabetic nephropathy or progression to end-stage renal disease. This highlights the complexity of HO-1's functions, which is also illustrated by the fact that, despite the abundance of preclinical data, no drug targeting HO-1 has so far been translated into clinical use. The objective of this review is to assess current knowledge relating HO-1's role in the kidney and its potential interest as a nephroprotection agent. The potential therapeutic openings will be presented, in particular through the identification of clinical trials targeting this enzyme or its products.

Insights into the ameliorative effect of oleic acid in rejuvenating phenylhydrazine induced oxidative stress mediated morpho-functionally dismantled erythrocytes

Phenylhydrazine (PHZ), an intermediate in the synthesis of fine chemicals is toxic for human health and environment. Despite of having severe detrimental effects on different physiological systems, exposure of erythrocytes to PHZ cause destruction of haemoglobin and membrane proteins leading to iron release and complete haemolysis of red blood cells (RBC). Involvement of oxidative stress behind such action triggers the urge for searching a potent antioxidant. The benefits of consuming olive oil is attributed to its 75% oleic acid (OA) content in average. Olive oil is the basic component of Mediterranean diet. Hence, OA has been chosen in our present in vitro study to explore its efficacy against PHZ (1 mM) induced alterations in erythrocytes. Four different concentrations of OA (0.01 nM, 0.02 nM, 0.04 nM and 0.06 nM) were primarily experimented with, among which 0.06 nM OA has shown to give maximal protection. This study demonstrates the capability of OA in preserving the morphology, intracellular antioxidant status and the activities of metabolic enzymes of RBCs that have been diminished by PHZ, through its antioxidant mechanisms. The results of the present study firmly establish OA as a promising antioxidant for conserving the health of erythrocyte from PHZ toxicity which indicate toward future possible use of OA either singly or in combination with other dietary components for protection of erythrocytes against PHZ induced toxic cellular changes.

The Serum and Saliva Proteome of Dogs with Diabetes Mellitus

This study aims to evaluate the changes in salivary and serum proteomes that occur in canine diabetes mellitus type-1 (DM) through a high-throughput quantitative proteomic analysis. The proteomes of 10 paired serum and saliva samples from healthy controls (HC group, n = 5) and dogs with untreated DM (DM group, n = 5) were analyzed using Tandem Mass Tags (TMT)-based proteomic approach. Additionally, 24 serum samples from healthy controls and untreated DM were used to validate haptoglobin in serum. The TMT analysis quantified 767 and 389 proteins in saliva and serum, respectively. Of those, 16 unique proteins in serum and 26 in saliva were differently represented between DM and HC groups. The verification of haptoglobin in serum was in concordance with the proteomic data. Our results pointed out changes in both saliva and serum proteomes that reflect different physiopathological changes in dogs with DM. Although some of the proteins identified here, such as malate dehydrogenase or glyceraldehyde-3-phosphate dehydrogenase, were previously related with DM in dogs, most of the proteins modulated in serum and saliva are described in canine DM for the first time and could be a source of potential biomarkers of the disease. Additionally, the molecular function, biological process, pathways and protein class of the differential proteins were revealed, which could improve the understanding of the disease's pathological mechanisms.

Mechanisms of haemolysis-induced kidney injury

Intravascular haemolysis is a fundamental feature of chronic hereditary and acquired haemolytic anaemias, including those associated with haemoglobinopathies, complement disorders and infectious diseases such as malaria. Destabilization of red blood cells (RBCs) within the vasculature results in systemic inflammation, vasomotor dysfunction, thrombophilia and proliferative vasculopathy. The haemoprotein scavengers haptoglobin and haemopexin act to limit circulating levels of free haemoglobin, haem and iron - potentially toxic species that are released from injured RBCs. However, these adaptive defence systems can fail owing to ongoing intravascular disintegration of RBCs. Induction of the haem-degrading enzyme haem oxygenase 1 (HO1) - and potentially HO2 - represents a response to, and endogenous defence against, large amounts of cellular haem; however, this system can also become saturated. A frequent adverse consequence of massive and/or chronic haemolysis is kidney injury, which contributes to the morbidity and mortality of chronic haemolytic diseases. Intravascular destruction of RBCs and the resulting accumulation of haemoproteins can induce kidney injury via a number of mechanisms, including oxidative stress and cytotoxicity pathways, through the formation of intratubular casts and through direct as well as indirect proinflammatory effects, the latter via the activation of neutrophils and monocytes. Understanding of the detailed pathophysiology of haemolysis-induced kidney injury offers opportunities for the design and implementation of new therapeutic strategies to counteract the unfavourable and potentially fatal effects of haemolysis on the kidney.

Tyrosyl radical in haemoglobin and haptoglobin-haemoglobin complex: how does haptoglobin make haemoglobin less toxic?

One of the difficulties in creating a blood substitute on the basis of human haemoglobin (Hb) is the toxic nature of Hb when it is outside the safe environment of the red blood cells. The plasma protein haptoglobin (Hp) takes care of the Hb physiologically leaked into the plasma – it binds Hb and makes it much less toxic while retaining the Hb's high oxygen transporting capacity. We used Electron Paramagnetic Resonance (EPR) spectroscopy to show that the protein bound radical induced by H₂O₂ in Hb and Hp-Hb complex is formed on the same tyrosine residue(s), but, in the complex, the radical is found in a more hydrophobic environment and decays slower than in unbound Hb, thus mitigating its oxidative capacity. The data obtained in this study might set new directions in engineering blood substitutes for transfusion that would have the oxygen transporting efficiency typical of Hb, but which would be non-toxic.

Involvement of placental growth factor upregulated via TGF-β1-ALK1-Smad1/5 signaling in prohaptoglobin-induced angiogenesis

A potential role of haptoglobin in arterial restructuring has been suggested, and our previous study demonstrated that prohaptoglobin, the precursor of haptoglobin, stimulates endothelial angiogenesis. However, the mechanisms underlying the angiogenic effects of prohaptoglobin are still unclear. Here, we investigated angiogenic signaling induced by prohaptoglobin using human umbilical vein endothelial cells. Prohaptoglobin upregulated the expression of placental growth factor (PlGF), vascular endothelial growth factor (VEGF)-A, and VEGF receptor 1 and 2, and also induced cell migration and tube network formation. PlGF knockdown attenuated these angiogenic effects of prohaptoglobin. Furthermore, a transcription factor profiling assay indicated that Smad is involved in PlGF expression in response to prohaptoglobin. Transforming growth factor-β1 (TGF-β1) expression and Smad1/5 phosphorylation were also induced by prohaptoglobin treatment. Blockade of TGF-β1 signaling using the TGF-β receptor kinase inhibitor LY2109761 or Smad1/5 siRNA reduced the prohaptoglobin-induced PlGF expression and in vitro tube formation. Knockdown of the TGF-β receptor ALK1, but not ALK5, with a specific siRNA blocked the Smad1/5 phosphorylation and PlGF expression induced by prohaptoglobin. These findings suggest that the angiogenic effects of prohaptoglobin are dependent on PlGF and mediated via a TGF-β1-ALK1-Smad1/5–PlGF/VEGFR1–VEGF-A/VEGFR2 signaling pathway.

Urinary Proteomics for the Early Diagnosis of Diabetic Nephropathy in Taiwanese Patients

Diabetic nephropathy (DN) is a major complication in diabetic patients. Microalbuminuria testing is used to identify renal disease; however, its predictive value is questionable. We aimed to identify urinary biomarkers to early diagnosis nephropathy before identifiable alternations in kidney function or urine albumin excretion occurs. Proteomic approaches were used to identify potential urinary biomarkers and enzyme-linked immunosorbent assay was performed to verify the results. The data identified haptoglobin (HPT) and α-1-microglobulin/bikunin precursor (AMBP) as two biomarkers with the highest ability to distinguish between healthy individuals and patients with nephropathy, and between diabetic patients with and without DN. Further, the HPT-to-creatinine ratio (HCR) was evaluated as an independent predictor of early renal functional decline (ERFD) in a cohort with an average follow-up of 4.2 years. The area under the curve (AUC) value for ERFD prediction was significantly improved when the HCR biomarker was included in the model with albumin to creatinine ratio (ACR) and baseline characteristics (AUC values were 0.803 and 0.759 for HCR and ACR, respectively; p value was 0.0423 for difference between models). In conclusion, our results suggest that HCR represents an early indicator of nephropathy, and a marker related to ERFD among diabetic patients in Taiwan.

Inflammation in sickle cell disease

The primary β-globin gene mutation that causes sickle cell disease (SCD) has significant pathophysiological consequences that result in hemolytic events and the induction of the inflammatory processes that ultimately lead to vaso-occlusion. In addition to their role in the initiation of the acute painful vaso-occlusive episodes that are characteristic of SCD, inflammatory processes are also key components of many of the complications of the disease including autosplenectomy, acute chest syndrome, pulmonary hypertension, leg ulcers, nephropathy and stroke. We, herein, discuss the events that trigger inflammation in the disease, as well as the mechanisms, inflammatory molecules and cells that propagate these inflammatory processes. Given the central role that inflammation plays in SCD pathophysiology, many of the therapeutic approaches currently under pre-clinical and clinical development for the treatment of SCD endeavor to counter aspects or specific molecules of these inflammatory processes and it is possible that, in the future, we will see anti-inflammatory drugs being used either together with, or in place of, hydroxyurea in those SCD patients for whom hematopoietic stem cell transplants and evolving gene therapies are not a viable option.

Characterization of Renal Injury and Inflammation in an Experimental Model of Intravascular Hemolysis

Intravascular erythrocyte destruction, accompanied by the release of pro-oxidative and pro-inflammatory components hemoglobin and heme, is a common event in the pathogenesis of numerous diseases with heterogeneous etiology and clinical features. A frequent adverse effect related to massive hemolysis is the renal injury and inflammation. Nevertheless, it is still unclear whether heme––a danger-associated molecular pattern––and ligand for TLR4 or upstream hemolysis-derived products are responsible for these effects. Well-characterized animal models of hemolysis with kidney impairment are needed to investigate how hemolysis drives kidney injury and to test novel therapeutic strategies. Here, we characterized the pathological processes leading to acute kidney injury and inflammation during massive intravascular hemolysis, using a mouse model of phenylhydrazine (PHZ)-triggered erythrocyte destruction. We observed profound changes in mRNA levels for markers of tubular damage (Kim-1, NGAL) and regeneration (indirect marker of tubular injury, Ki-67), and tissue and vascular inflammation (IL-6, E-selectin, P-selectin, ICAM-1) in kidneys of PHZ-treated mice, associated with ultrastructural signs of tubular injury. Moreover, mass spectrometry revealed presence of markers of tubular damage in urine, including meprin-α, cytoskeletal keratins, α-1-antitrypsin, and α-1-microglobulin. Signs of renal injury and inflammation rapidly resolved and the renal function was preserved, despite major changes in metabolic parameters of PHZ-injected animals. Mechanistically, renal alterations were largely heme-independent, since injection of free heme could not reproduce them, and scavenging heme with hemopexin in PHZ-administered mice could not prevent them. Reduced overall health status of the mice suggested multiorgan involvement. We detected amylasemia and amylasuria, two markers of acute pancreatitis. We also provide detailed characterization of renal manifestations associated with acute intravascular hemolysis, which may be mediated by hemolysis-derived products upstream of heme release. This analysis provides a platform for further investigations of hemolytic diseases and associated renal injury and the evaluation of novel therapeutic strategies that target intravascular hemolysis.

Haptoglobin Genotypes in Nasopharyngeal Carcinoma

Aim

Haptoglobin polymorphisms are associated with different cancers; however, the occurrence of nasopharyngeal carcinoma (NPC) in relation to haptoglobin polymorphisms has not been reported. In this study, the distribution of haptoglobin genotypes among patients with NPC was investigated and the prognostic significance of haptoglobin genotypes was further analyzed.

Material and methods

Haptoglobin genotypes were analyzed using polymerase chain reaction and electrophoresis. The genotypes were determined in the sera of 49 NPC patients and in 134 controls.

Results

The haptoglobin genotypes of patients with NPC were as follows: Hp 1–1, 2%; Hp 2–1, 39%; Hp 2–2, 59%. The frequency of the Hp 2–2 genotype was much higher in NPC patients than in control individuals (p=0.044). Furthermore, NPC patients with the Hp 2–2 genotype had advanced T stages (p=0.001) and larger primary tumor volumes (p=0.035) than those with Hp 2–1 or 1–1.

Conclusion

An increased frequency of the Hp 2–2 genotype was associated with NPC. The Hp 2 allele was also overexpressed in NPC patients. NPC patients with the Hp 2–2 genotype had advanced T stage and a larger primary tumor volume. Hp 2–2 may be a negative prognostic factor in NPC.

Modulatory effects of melatonin and vitamin C on oxidative stress-mediated haemolytic anaemia and associated cardiovascular dysfunctions in rats

Background Phenylhydrazine (PHE) in experimental animal models has been widely reported to cause haemolytic anaemia, via the induction of oxidative stress and thus causing deleterious cardiovascular complications. Hence, this study was designed to evaluate the possible modulatory role of melatonin (MLT) or vitamin C when co-administered with PHE. Methods Anaemia was established with PHE administration. MLT or vitamin C was co-administered with PHE. Haematological parameters, markers of oxidative stress, enzymic and non-enzymic antioxidants, blood pressure and electrocardiograms were assessed. Results PHE administration led to a significant (p<0.05) increase in malondialdehyde (MDA), and hydrogen peroxide (H2O2) generated in cardiac, renal and red blood cell (RBC) lysates. PHE also significantly reduced the activity of glutathione peroxidase (GPx), superoxide dismutase (SOD) and reduced glutathione (GSH) contents, respectively. The RBC counts, haemoglobin (Hb) concentration and packed cell volume (PCV) were also significantly reduced following the administration of PHE. Furthermore, the systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial blood pressure (MABP) increased significantly in rats administered PHE alone. Similarly, PHE administration led to a significant drop in heart rate but prolonged QRS, QT and QTc interval. Pathology of the heart and kidney was also observed in PHE treated group. However, treatment with MLT and vitamin C improved enzymic and non-enzymic antioxidant system together with the restoration of SBP, DBP and MABP to near normal. The architectural anarchy observed in the heart and kidney of PHE administered rats was reversed to some extent. Conclusions Hence, MLT and vitamin C could be employed as therapeutic targets in various cardiovascular diseases and its complications.

Changes in concentrations of haemostatic and inflammatory biomarkers in synovial fluid after intra-articular injection of lipopolysaccharide in horses

Background

Septic arthritis is a common and potentially devastating disease characterized by severe intra-articular (IA) inflammation and fibrin deposition. Research into equine joint pathologies has focused on inflammation, but recent research in humans suggests that both haemostatic and inflammatory pathways are activated in the joint compartment in arthritic conditions. The aim of this study was to characterize the IA haemostatic and inflammatory responses in horses with experimental lipopolysaccharide (LPS)-induced joint inflammation. Inflammation was induced by IA injection of LPS into one antebrachiocarpal joint of six horses. Horses were evaluated clinically with subjective grading of lameness, and blood and synovial fluid (SF) samples were collected at post injection hours (PIH) -120, −96, −24, 0, 2, 4, 8, 16, 24, 36, 48, 72 and 144. Total protein (TP), white blood cell counts (WBC), serum amyloid A (SAA), haptoglobin, iron, fibrinogen, thrombin-antithrombin (TAT) and d-dimer concentrations were assessed in blood and SF.

Results

Intra-articular injection of LPS caused local and systemic signs of inflammation including increased rectal temperature, lameness and increased joint circumference and skin temperature. Most of the biomarkers (TP, WBC, haptoglobin, fibrinogen and TAT) measured in SF increased quickly after LPS injection (at PIH 2–4), whereas SAA and d-dimer levels increased more slowly (at PIH 16 and 144, respectively). SF iron concentrations did not change statistically significantly. Blood WBC, SAA, haptoglobin and fibrinogen increased and iron decreased significantly in response to the IA LPS injection, while TAT and d-dimer concentrations did not change. Repeated pre-injection arthrocenteses caused significant changes in SF concentrations of TP, WBC and haptoglobin.

Conclusion

Similar to inflammatory joint disease in humans, joint inflammation in horses was accompanied by an IA haemostatic response with changes in fibrinogen, TAT and d-dimer concentrations. Inflammatory and haemostatic responses were induced simultaneously and may likely interact. Further studies of interactions between the two responses are needed for a better understanding of pathogenesis of joint disease in horses. Knowledge of effects of repeated arthrocenteses on levels of SF biomarkers may be of value when markers are used for diagnostic purposes.

Zonulin transgenic mice show altered gut permeability and increased morbidity/mortality in the DSS colitis model

Increased small intestinal permeability (IP) has been proposed to be an integral element, along with genetic makeup and environmental triggers, in the pathogenies of chronic inflammatory diseases (CIDs). We identified zonulin as a master regular of intercellular tight junctions linked to the development of several CIDs. We aim to study the role of zonulin-mediated IP in the pathogenesis of CIDs. Zonulin transgenic Hp2 mice (Ztm) were subjected to dextran sodium sulfate (DSS) treatment for 7 days, followed by 4-7 days' recovery and compared to C57Bl/6 (wild-type (WT)) mice. IP was measured in vivo and ex vivo, and weight, histology, and survival were monitored. To mechanistically link zonulin-dependent impairment of small intestinal barrier function with clinical outcome, Ztm were treated with the zonulin inhibitor AT1001 added to drinking water in addition to DSS. We observed increased morbidity (more pronounced weight loss and colitis) and mortality (40-70% compared with 0% in WT) at 11 days post-DSS treatment in Ztm compared with WT mice. Both in vivo and ex vivo measurements showed an increased IP at baseline in Ztm compared to WT mice, which was exacerbated by DSS treatment and was associated with upregulation of zonulin gene expression (fourfold in the duodenum, sixfold in the jejunum). Treatment with AT1001 prevented the DSS-induced increased IP both in vivo and ex vivo without changing zonulin gene expression and completely reverted morbidity and mortality in Ztm. Our data show that zonulin-dependent small intestinal barrier impairment is an early step leading to the break of tolerance with subsequent development of CIDs.

Urinary haptoglobin, alpha-1 anti-chymotrypsin and retinol binding protein identified by proteomics as potential biomarkers for lupus nephritis

The study was aimed at identification by proteomics and validation by enzyme-linked immunosorbent assay (ELISA) of potential urinary biomarkers for lupus nephritis. Study subjects comprised 88 systemic lupus erythematosus (SLE) patients and 60 controls (rheumatoid arthritis, diabetes mellitus and healthy individuals). Based on the SLE disease activity index (SLEDAI), patients were classified as active renal (AR), active non-renal (ANR) or inactive disease (ID). Urinary proteins from a group of patients with AR or ID were resolved by two-dimensional gel electrophoresis and identified by matrix-assisted laser desorption ionization-time of flight-mass spectrometry (MALDI-TOF-MS/MS). The selected biomarkers were validated by ELISA using samples from all patients and controls. AR patients were followed-up for 12 months after start of therapy. Three urinary proteins, alpha-1 anti-chymotrypsin (ACT), haptoglobin (HAP) and retinol binding protein (RBP), were detected in patients with AR and not ID. Upon validation, ACT levels were higher in AR patients than the other groups (P < 0·001) and showed good correlation with renal SLEDAI (r = 0·577, P < 0·001) as well as SLEDAI (r = 0·461, P < 0·001). Similarly, HAP levels were > 10-fold higher in AR than other groups (P < 0·001) and correlated well with renal SLEDAI (r = 0·594, P < 0·001) and SLEDAI (r = 0·371, P < 0·01). RBP levels were also higher in AR patients than in other groups (P < 0·05), except diabetes, and showed moderate correlation with renal SLEDAI (r = 0·284, P < 0·008) and SLEDAI (r = 0·316, P < 0·003). Upon follow-up with treatment, levels of all three proteins declined at 6 and 12 months (P < 0·01). Multiple logistic regression identified ACT as the best marker to differentiate AR from ANR. Urinary HAP, ACT and RBP are potential biomarkers for lupus nephritis activity.

Detection of Occult Acute Kidney Injury in Glucose-6-Phosphate Dehydrogenase Deficiency Anemia

BACKGROUND

Glucose-6-phosphate dehydrogenase (G6PD) deficiency anemia is associated with intravascular hemolysis. The freely filtered hemoglobin can damage the kidney. We aimed to assess any subclinical renal injury in G6PD children.

METHODS

Sixty children were included. Thirty G6PD deficiency anemia children were enrolled during the acute hemolytic crisis and after the hemolytic episode had elapsed. Another thirty healthy children were included as controls. Serum cystatin C, creatinine levels, and urinary albumin/creatinine (A/C) ratio were measured, and the glomerular filtration rate (GFR) was calculated.

RESULTS

Significantly higher urinary A/C ratio (p=0.001,0.002 respectively) and lower GFR (p=0.001 for both) were found during hemolysis and after the hemolytic episode compared to the controls. Also, significant higher serum cystatin C (p=0.001), creatinine (p=0.05) and A/C (p= 0.001) ratio and insignificant lower GFR (p=0.3) during acute hemolytic crisis compared to the same children after the hemolytic episode subsided.

CONCLUSIONS

G6PD deficiency anemia is associated with a variable degree of acute renal injury during acute hemolytic episodes which may persist after elapsing of the hemolytic crises.

Sustained treatment of sickle cell mice with haptoglobin increases HO-1 and H-ferritin expression and decreases iron deposition in the kidney without improvement in kidney function

There is growing evidence that extracellular haemoglobin and haem mediate inflammatory and oxidative damage in sickle cell disease. Haptoglobin (Hp), the scavenger for free haemoglobin, is depleted in most patients with sickle cell disease due to chronic haemolysis. Although single infusions of Hp can ameliorate vaso-occlusion in mouse models of sickle cell disease, prior studies have not examined the therapeutic benefits of more chronic Hp dosing on sickle cell disease manifestations. In the present study, we explored the effect of Hp treatment over a 3-month period in sickle mice at two dosing regimens: the first at a moderate dose of 200 mg/kg thrice weekly and the second at a higher dose of 400 mg/kg thrice weekly. We found that only the higher dosing regimen resulted in increased haem-oxygenase-1 and heavy chain ferritin (H-ferritin) expression and decreased iron deposition in the kidney. Despite the decreased kidney iron deposition following Hp treatment, there was no significant improvement in kidney function. However, there was a nearly significant trend towards decreased liver infarction.

Human plasma protein N-glycosylation

Glycosylation is the most abundant and complex protein modification, and can have a profound structural and functional effect on the conjugate. The oligosaccharide fraction is recognized to be involved in multiple biological processes, and to affect proteins physical properties, and has consequentially been labeled a critical quality attribute of biopharmaceuticals. Additionally, due to recent advances in analytical methods and analysis software, glycosylation is targeted in the search for disease biomarkers for early diagnosis and patient stratification. Biofluids such as saliva, serum or plasma are of great use in this regard, as they are easily accessible and can provide relevant glycosylation information. Thus, as the assessment of protein glycosylation is becoming a major element in clinical and biopharmaceutical research, this review aims to convey the current state of knowledge on the N-glycosylation of the major plasma glycoproteins alpha-1-acid glycoprotein, alpha-1-antitrypsin, alpha-1B-glycoprotein, alpha-2-HS-glycoprotein, alpha-2-macroglobulin, antithrombin-III, apolipoprotein B-100, apolipoprotein D, apolipoprotein F, beta-2-glycoprotein 1, ceruloplasmin, fibrinogen, immunoglobulin (Ig) A, IgG, IgM, haptoglobin, hemopexin, histidine-rich glycoprotein, kininogen-1, serotransferrin, vitronectin, and zinc-alpha-2-glycoprotein. In addition, the less abundant immunoglobulins D and E are included because of their major relevance in immunology and biopharmaceutical research. Where available, the glycosylation is described in a site-specific manner. In the discussion, we put the glycosylation of individual proteins into perspective and speculate how the individual proteins may contribute to a total plasma N-glycosylation profile determined at the released glycan level.

Perioperative intravenous acetaminophen attenuates lipid peroxidation in adults undergoing cardiopulmonary bypass: a randomized clinical trial

BACKGROUND

Cardiopulmonary bypass (CPB) lyses erythrocytes and induces lipid peroxidation, indicated by increasing plasma concentrations of free hemoglobin, F2-isoprostanes, and isofurans. Acetaminophen attenuates hemeprotein-mediated lipid peroxidation, reduces plasma and urine concentrations of F2-isoprostanes, and preserves kidney function in an animal model of rhabdomyolysis. Acetaminophen also attenuates plasma concentrations of isofurans in children undergoing CPB. The effect of acetaminophen on lipid peroxidation in adults has not been studied. This was a pilot study designed to test the hypothesis that acetaminophen attenuates lipid peroxidation in adults undergoing CPB and to generate data for a clinical trial aimed to reduce acute kidney injury following cardiac surgery.

METHODS AND RESULTS

In a prospective double-blind placebo-controlled clinical trial, sixty adult patients were randomized to receive intravenous acetaminophen or placebo starting prior to initiation of CPB and for every 6 hours for 4 doses. Acetaminophen concentrations measured 30 min into CPB and post-CPB were 11.9 ± 0.6 μg/mL (78.9 ± 3.9 μM) and 8.7 ± 0.3 μg/mL (57.6 ± 2.0 μM), respectively. Plasma free hemoglobin increased more than 15-fold during CPB, and haptoglobin decreased 73%, indicating hemolysis. Plasma and urinary markers of lipid peroxidation also increased during CPB but returned to baseline by the first postoperative day. Acetaminophen reduced plasma isofuran concentrations over the duration of the study (P = 0.05), and the intraoperative plasma isofuran concentrations that corresponded to peak hemolysis were attenuated in those subjects randomized to acetaminophen (P = 0.03). Perioperative acetaminophen did not affect plasma concentrations of F2-isoprostanes or urinary markers of lipid peroxidation.

CONCLUSIONS

Intravenous acetaminophen attenuates the increase in intraoperative plasma isofuran concentrations that occurs during CPB, while urinary markers were unaffected.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01366976.

Proteomic identification of fucosylated haptoglobin alpha isoforms in ascitic fluids and its localization in ovarian carcinoma tissues from Mexican patients

Background

Ovarian cancer is the most lethal gynecologic disease due to delayed diagnosis, and ascites production is a characteristic of patients in advanced stages. The aim of this study was to perform the proteomic analysis of ascitic fluids of Mexican patients with ovarian carcinoma, in order to detect proteins with a differential expression pattern in the continuing search to identify biomarkers for this disease.

Methods

Samples were collected from 50 patients from the Instituto Nacional de Cancerología of México under informed consent and with approval of the bioethics and scientific committees. After elimination of abundant proteins (Albumin/IgGs) samples were processed for 2D electrophoresis and further protein identification by Mass Spectrometry (MALDI-TOF). Molecules of interest were followed by western blot and lectin binding assays, and their tissue location by histo-immunofluorescence and confocal analysis.

Results and discussion

An area with a differential expression pattern among samples was located in the 2D gels. Identified proteins were 6 alpha 1 isoforms and 1 alpha 2 isoform of Haptoglobin, and 2 isoforms of Transthyretin. While Transthyretin isoforms were constitutively expressed in all samples, clear differences in the expression pattern of Haptoglobin alpha isoforms were found. Moreover, increased levels of fucosylation of Haptoglobin alpha isoforms analyzed in 40 samples by Aleuria aurantia lectin binding by 1D overlay assay showed a positive correlation with advanced stages of the disease. Tissue detection of Haptoglobin and its fucosylated form, by histo-immunofluorescence in biopsies of ovarian cancer, also showed a correlation with ovarian cancer progression. Moreover, results show that fucosylated Haptoglobin is produced by tumor cells.

Conclusions

Increased numbers of highly fucosylated Haptoglobin alpha isoforms in ascitic fluids and the presence of fucosylated Haptoglobin in tumor tissues of ovarian cancer Mexican patients associated with advanced stages of the disease, reinforce the potential of fucosylated Haptoglobin alpha isoforms to be characterized as biomarkers for disease progression.

Identification of a specific haptoglobin C-terminal fragment in arthritic synovial fluid and its effect on interleukin-6 expression

Haptoglobin (Hp), a major acute-phase plasma protein, has been found in arthritic synovial fluid (SF). However, the function and structural modifications of Hp in arthritic SF are unknown. To investigate in vivo generation of modified Hp associated with inflammatory disease, we examined a new Hp isoform in SF from patients with rheumatoid arthritis (RA). Specific Hp fragments of 28 000 and 15 000 molecular weight were identified in SF of patients with RA, and the two polypeptides were presumed to be fragments of the Hp β-chain (43 000 MW) produced by cleavage with plasmin. The 15 000 MW fragment, which is a C-terminal region of Hp, was observed at higher frequency and levels in RA than in osteoarthritis. Plasmin activity was also higher in SF of RA patients. A recombinant 15 000 MW Hp fragment up-regulated interlukin-6 expression in monocytic cells. These findings indicate that the C-terminal Hp fragment is generated by plasmin in local inflammatory environments and acts as an inflammatory mediator. They further suggest that a specific Hp fragment might be applied as a novel biomarker for the diagnosis and prognosis of inflammatory diseases such as RA.

A unique form of haptoglobin produced by murine hematopoietic cells supports B-cell survival, differentiation and immune response

Haptoglobin (Hp), an acute phase reactant and major hemoglobin-binding protein, has a unique role in host immunity. Previously, we demonstrated that Hp-deficient C57BL/6J mice exhibit stunted development of mature T- and B-cells resulting in markedly lower levels of antigen-specific IgG. The current study identified leukocyte-derived pro-Hp as a relevant mediator of an optimal immune response. Reconstitution of Hp-/- mice with Hp+/+ bone marrow restored normal immune response to ovalbumin. Furthermore, transplanting a mixture of bone marrow-derived from B-cell-deficient and Hp-deficient mice into Rag1-/-/Hp+/+ recipients resulted in mice with a defective immune response similar to Hp-/- mice. This suggests that Hp generated by the B-cell compartment, rather than by the liver, is functionally contributing to a normal immune response. Leukocytes isolated from the spleen express Hp and release a non-proteolytically processed pro-Hp that uniquely differed from liver-derived Hp by not binding to hemoglobin. While addition of purified plasma Hp to cultured B-cells did not alter responses, pro-Hp isolated from splenocytes enhanced cellular proliferation and production of IgG. Collectively, the comparison of wild-type and Hp-deficient mice suggests a novel regulatory activity for lymphocyte-derived Hp, including Hp produced by B-cells themselves, that supports in vivo survival and functional differentiation of the B-cells to ensure an optimal immune response.

Urine haptoglobin levels predict early renal functional decline in patients with type 2 diabetes

Diabetic nephropathy is the leading cause of end-stage renal disease. The urinary albumin to creatinine ratio is used as a predictor for the development of nephropathy but it is neither sensitive nor specific. Here we used liquid chromatography/mass spectrometry on urine of eight normoalbuminuric patients with type 2 diabetes from the VA Diabetes Trial to identify candidate markers for loss of renal function. Initial verification of seven markers (agrin, haptoglobin, mannan-binding lectin serine protease 2, LAMP-2, angiotensinogen, NGAL, and uromodulin) in the urine of an additional 30 patients showed that haptoglobin was the best predictor of early renal functional decline. We then measured this in the urine of 204 patients with type 2 diabetes who did not yet have significant kidney disease (estimated glomerular filtration rate stage 2 or better and an albumin to creatinine ratio <300 mg/g). In comparing the highest to lowest tertiles, the odds ratio for having early renal function decline was 2.70 (CI: 1.15, 6.32) using the haptoglobin to creatinine ratio compared with 2.50 (CI 1.14, 5.48) using the albumin to creatinine ratio after adjusting for treatment group and use of ACE inhibitors. Addition of the haptoglobin to creatinine ratio to a model using the albumin to creatinine ratio to predict early renal function decline resulted in improved predictive performance. Thus, the haptoglobin to creatinine ratio may be useful to predict patients with type 2 diabetes at risk of nephropathy before the development of macroalbuminuria or reduced glomerular filtration rate.

Lack of haptoglobin results in unbalanced VEGFα/angiopoietin-1 expression, intramural hemorrhage and impaired wound healing after myocardial infarction

Decreased haptoglobin (Hp) functionality due to allelic variations is associated with worsened outcome in patients after myocardial infarction (MI). However, mechanisms through which haptoglobin deficiency impairs cardiac repair remain to be elucidated. In the present study, we identified novel molecular alterations mediated by Hp involved in early and late cardiac repair responses after left coronary artery ligation in Hp(-/-) and wild-type (WT) mice. We observed a higher mortality rate in Hp(-/-) mice despite similar infarct size between groups. Deaths were commonly caused by cardiac rupture in Hp(-/-) animals. Histological analysis of 3 and 7days old non-ruptured infarcted hearts revealed more frequent and more severe intramural hemorrhage and increased leukocyte infiltration in Hp(-/-) mice. Analyses of non-ruptured hearts revealed increased oxidative stress, reduced PAI-1 activity and enhanced VEGFα transcription in Hp(-/-) mice. In line with these observations, we found increased microvascular permeability in Hp(-/-) hearts 3days after infarction. In vitro, haptoglobin prevented hemoglobin-induced oxidative stress and restored VEGF/Ang-1 balance in endothelial cell cultures. During long-term follow-up of the surviving animals, we observed altered matrix turnover, impaired scar formation and worsened cardiac function and geometry in Hp(-/-)mice. In conclusion, haptoglobin deficiency severely deteriorates tissue repair and cardiac performance after experimental MI. Haptoglobin plays a crucial role in both short- and long-term cardiac repair responses by reducing oxidative stress, maintaining microvascular integrity, myocardial architecture and proper scar formation.

A novel hemoglobin-binding peptide reduces cell-free hemoglobin in murine hemolytic anemia

Hemolysis can saturate the hemoglobin (Hb)/heme scavenging system, resulting in increased circulating cell-free Hb (CF-Hb) in hereditary and acquired hemolytic disease. While recent studies have suggested a central role for intravascular hemolysis and CF-Hb in the development of vascular dysfunction, this concept has stimulated considerable debate. This highlights the importance of determining the contribution of CF-Hb to vascular complications associated with hemolysis. Therefore, a novel Hb-binding peptide was synthesized and linked to a small fragment of apolipoprotein E (amino acids 141-150) to facilitate endocytic clearance. Plasma clearance of hE-Hb-b10 displayed a rapid phase t(1/2) of 16 min and slow phase t(1/2) of 10 h, trafficking primarily through the liver. Peptide hE-Hb-B10 decreased CF-Hb in mice treated with phenylhydrazine, a model of acute hemolysis. Administration of hE-Hb-B10 also attenuated CF-Hb in two models of chronic hemolysis: Berkeley sickle cell disease (SS) mice and mice with severe hereditary spherocytosis (HS). The hemolytic rate was unaltered in either chronic hemolysis model, supporting the conclusion that hE-Hb-B10 promotes CF-Hb clearance without affecting erythrocyte lysis. Interestingly, hE-Hb-B10 also decreased plasma ALT activity in SS and HS mice. Although acetylcholine-mediated facialis artery vasodilation was not improved by hE-Hb-B10 treatment, the peptide shifted vascular response in favor of NO-dependent vasodilation in SS mice. Taken together, these data demonstrate that hE-Hb-B10 decreases CF-Hb with a concomitant reduction in liver injury and changes in vascular response. Therefore, hE-Hb-B10 can be used to investigate the different roles of CF-Hb in hemolytic pathology and may have therapeutic benefit in the treatment of CF-Hb-mediated tissue damage.

Proximal tubule haptoglobin gene activation is an integral component of the acute kidney injury "stress response"

Haptoglobin (Hp) synthesis occurs almost exclusively in liver, and it is rapidly upregulated in response to stress. Because many of the pathways that initiate hepatic Hp synthesis are also operative during acute kidney injury (AKI), we tested whether AKI activates the renal cortical Hp gene. CD-1 mice were subjected to six diverse AKI models: ischemia-reperfusion, glycerol injection, cisplatin nephrotoxicity, myoglobinuria, endotoxemia, and bilateral ureteral obstruction. Renal cortical Hp gene induction was determined either 4-72 h or 1-3 wk later by measuring Hp mRNA and protein levels. Relative renal vs. hepatic Hp gene induction during endotoxemia was also assessed. Each form of AKI induced striking and sustained Hp mRNA increases, leading to ∼10- to 100-fold renal Hp protein elevations (ELISA; Western blot). Immunohistochemistry, and isolated proximal tubule assessments, indicated that the proximal tubule was the dominant (if not only) site of the renal Hp increases. Corresponding urinary and plasma Hp elevations were surrogate markers of this response. Endotoxemia evoked 25-fold greater Hp mRNA increases in kidney vs. liver, indicating marked renal Hp gene reactivity. Clinical relevance of these findings was suggested by observations that urine samples from 16 patients with established AKI had statistically higher (∼12×) urinary Hp levels than urine samples from either normal subjects or from 15 patients with chronic kidney disease. These AKI-associated urinary Hp increases mirrored those seen for urinary neutrophil gelatinase-associated lipoprotein, a well accepted AKI biomarker gene. In summary, these studies provide the first evidence that AKI evokes rapid, marked, and sustained induction of the proximal tubule Hp gene. Hp's known antioxidant, as well as its protean pro- and anti-inflammatory, actions imply potentially diverse effects on the evolution of acute tubular injury.

Proteomic analysis of plasma proteins in diabetic rats by 2D electrophoresis and MALDI-TOF-MS

Despite tremendous advances in our understanding of the molecular basis of diabetes mellitus, substantial gaps still remain in our understanding of disease pathogenesis and in the development of effective strategies for early diagnosis and treatment. The proteomic approach has offered many opportunities and challenges in identifying new marker proteins and therapeutic targets, i.e., using 2D-polyacrylamide gel electrophoresis and matrix-assisted laser desorption/ionisation-time of flight mass spectrometry. The differential protein expressions were analyzed in alloxan-induced diabetic rats treated with Cynodon dactylon leaf extract. The plant extract was administered for 15 days that resulted in a significant increase in plasma insulin and C-peptide levels. We have also identified four differentially expressed proteins from rat plasma. These four diabetes-associated proteins were broadly classified into three groups as per their function: (1) lipid metabolism-associated protein (Apo A-IV), (2) antioxidant activity-related proteins [preprohaptoglobin and heat shock proteins B8 (HspB8)], and (3) muscle function-related protein (TPM3). Apo A-IV, HspB8, and preprohaptoglobin may play a key role in the recovery of diabetes mellitus and also prevent the diabetes-associated complications such as prevention of oxidative stress due to free radical and free hemoglobin. These results show the value of proteomic approach in identifying the potential markers that may eventually serve as diagnostic markers or therapeutic targets.

Constitutive immune function in European starlings, Sturnus vulgaris, is decreased immediately after an endurance flight in a wind tunnel

Life-history theory predicts that animals face a trade-off in energy allocation between performing strenuous exercise, such as migratory flight, and mounting an immune response. We experimentally tested this prediction by studying immune function in European starlings, Sturnus vulgaris, flown in a wind tunnel. Specifically, we predicted that constitutive immune function decreases in response to training and, additionally, in response to immediate exercise. We compared constitutive immune function among three groups: (1) ‘untrained’ birds that were kept in cages and were not flown; (2) ‘trained’ birds that received flight training over a 15 day period and performed a 1-4 h continuous flight, after which they rested for 48 h before being sampled; and (3) ‘post-flight’ birds that differed from the ‘trained’ group only in being sampled immediately after the final flight. A bird in our trained group represents an individual during migration that has been resting between migratory flights for at least 2 days. A bird in our post-flight group represents an individual that has just completed a migratory flight and has not yet had time to recover. Three of our four indicators (haptoglobin, agglutination and lysis) showed the predicted decrease in immune function in the post-flight group, and two indicators (haptoglobin, agglutination) showed the predicted decreasing trend from the untrained to trained to post-flight group. Haptoglobin levels were negatively correlated with flight duration. No effect of training or flight was detected on leukocyte profiles. Our results suggest that in European starlings, constitutive immune function is decreased more as a result of immediate exercise than of exercise training. Because of the recent emergence of avian-borne diseases, understanding the trade-offs and challenges faced by long-distance migrants has gained a new level of relevance and urgency.

Haptoglobin polymorphism as a risk factor for chronic kidney disease: a case-control study

AIMS

Taiwan has the highest incidence and prevalence of end-stage renal disease worldwide. Haptoglobin (Hp) has a role in renal protection, and there are known differences in the function of different Hp alleles. We aim to study the association between Hp genotype and chronic kidney disease (CKD) in Taiwan.

METHODS

We performed one hospital-based, age-matched case-control study of 213 patients with CKD and 213 controls to evaluate the association between Hp polymorphism and CKD. Three major Hp genotypes were determined using polymerase chain reaction and electrophoresis. An unconditional logistic regression model was used to identify the associated risk factors for the development of CKD.

RESULTS

The frequency of Hp2-2 genotype and Hp(2) allele was significantly higher in the CKD group than in controls (p = 0.032 and 0.024, respectively). After adjustment for covariates, the Hp2-2 genotype (vs. Hp1-1; OR 3.841) remained significantly associated with the development of CKD, together with diabetes (OR 3.131), hypertension (OR 1.748) and dyslipidemia (OR 1.646).

CONCLUSION

This present study shows that Hp2-2 genotype is an independent risk factor for CKD. Determination of the Hp genotype may be of potential value to the prediction of genetic risk for CKD.

Hypoxia-inducible factor-1alpha enhances haptoglobin gene expression by improving binding of STAT3 to the promoter

Haptoglobin (Hp) is known to play a role in angiogenesis as well as in anti-inflammation. STAT3 is a major transcription factor for expression of human Hp. We investigated whether hypoxia-inducible factor-1α (HIF-1α), a key mediator of angiogenesis, participates in Hp gene expression. HIF-1α overexpression by gene transfection or hypoxia augmented Hp transcription in HepG2 human hepatoma cells. Conversely, knockdown of HIF-1α by specific siRNA transfection diminished Hp expression, although the level of STAT3 phosphorylation remained unchanged. A luciferase reporter assay using mutant Hp promoters demonstrated that two adjacent DNA elements, a STAT3-binding element (SBE) and a cAMP-response element (CRE)-like site in human Hp promoter -120/-97, were required for HIF-1α-stimulated transactivation of the Hp gene. HIF-1α, STAT3, and p300/CBP were simultaneously bound to the SBE/CRE as a complex form. When HIF-1α was knocked down, STAT3 binding to the SBE in the Hp promoter was attenuated. Our findings suggest that HIF-1α assists STAT3 in strong binding to the proximal SBE in the Hp promoter. The CRE-like site located near the SBE may contribute to the formation of a stable complex of STAT3, HIF-1α, and p300/CBP, which leads to maximum transcription of the Hp gene.

Hemoglobin and heme scavenger receptors

Heme, the functional group of hemoglobin, myoglobin, and other hemoproteins, is a highly toxic substance when it appears in the extracellular milieu. To circumvent potential harmful effects of heme from hemoproteins released during physiological or pathological cell damage (such as hemolysis and rhabdomyolysis), specific high capacity scavenging systems have evolved in the mammalian organism. Two major systems, which essentially function in a similar way by means of a circulating latent plasma carrier protein that upon ligand binding is recognized by a receptor, are represented by a) the hemoglobin-binding haptoglobin and the receptor CD163, and b) the heme-binding hemopexin and the receptor low density lipoprotein receptor-related protein/CD91. Apart from the disclosure of the molecular basis for these important heme scavenging systems by identifying the functional link between the carrier proteins and the respective receptors, research over the last decade has shown how these systems, and the metabolic pathways they represent, closely relate to inflammation and other biological events.

Toxicological consequences of extracellular hemoglobin: biochemical and physiological perspectives

Under normal physiology, human red blood cells (RBCs) demonstrate a circulating lifespan of approximately 100-120 days with efficient removal of senescent RBCs taking place via the reticuloendothelial system, spleen, and bone marrow phagocytosis. Within this time frame, hemoglobin (Hb) is effectively protected by efficient RBC enzymatic systems designed to allow for interaction between Hb and diffusible ligands while preventing direct contact between Hb and the external environment. Under normal resting conditions, the concentration of extracellular Hb in circulation is therefore minimal and controlled by specific plasma and cellular (monocyte/macrophage) binding proteins (haptoglobin) and receptors (CD163), respectively. However, during pathological conditions leading to hemolysis, extracellular Hb concentrations exceed normal plasma and cellular binding capacities, allowing Hb to become a biologically relevant vasoactive and redox active protein within the circulation and at extravascular sites. Under conditions of genetic, drug-induced, and autoimmune hemolytic anemias, large quantities of Hb are introduced into the circulation and often lead to acute renal failure and vascular dysfunction. Interestingly, the study of chemically modified Hb for use as oxygen therapeutics has allowed for some basic understanding of extracellular Hb toxicity, particularly in the absence of functional clearance mechanisms and in circulatory antioxidant depleted states.

Differential proteomic characterization between normal peritoneal fluid and diabetic peritoneal dialysate

BACKGROUND

Since the mechanism of comorbidity and mortality in peritoneal dialysis is unclear, a comparison of peritoneal dialysate and normal peritoneal fluid may provide clues to the biological and pathological processes involved in peritoneal damage.

METHODS

Peritoneal dialysate and control samples were collected from five diabetes mellitus (DM) patients and two patients receiving laparoscopic cholecystectomy. Proteins were separated by two-dimensional gel electrophoresis (2D-GE). After image analysis, altered gel spots between these two sample groups were subjected to tryptic digestion and mass spectrometry analysis. The results were searched against the NCBI database.

RESULTS

A total of 26 protein spots were considered altered in 2D-GE between the two sample groups. After western blotting confirmation, vitamin D-binding protein, haptoglobin and alpha-2-microglobulin were at higher levels in the DM samples, while complement C4-A and IGK@ protein were at lower levels compared to the control samples.

CONCLUSION

The loss of vitamin D-binding protein, haptoglobin and alpha-2-microglobulin may be due to a change in the permeability of the peritoneal membrane to middle-sized proteins or leakage from peritoneal inflammation. Lower levels of complement C4-A in dialysate may shed light on the beginning of peritoneal membrane scleroses.

Enhancement of angiogenic and vasculogenic potential of endothelial progenitor cells by haptoglobin

Endothelial progenitor cells (EPCs) were transfected with the haptoglobin (Hp) gene to investigate the effect of Hp on cell function. Hp potentiated the gene expression of various pro-angiogenic factors in the EPCs. The Hp-modified EPCs also increased in vitro tube formation on Matrigel compared with control cells. In hindlimb ischaemia models, Hp-EPCs showed a greater ability for improving blood perfusion and recovery from ischaemic injury. These results indicate that Hp improves EPC function in neovasculogenesis, which suggests that ex vivo modification of EPCs with the Hp gene can be applied to the treatment of vascular damage.

Hemoglobin neurotoxicity is attenuated by inhibitors of the protein kinase CK2 independent of heme oxygenase activity

The heme oxygenase (HO) enzymes catalyze the rate-limiting step of heme breakdown, and may accelerate oxidative injury to neurons exposed to heme or hemoglobin. HO-1 and HO-2 are activated in vitro by the phos-phatidylinositol 3-kinase (PI3K)/Akt and protein kinase C (PKC)/CK2 pathways, respectively. The present study tested the hypotheses that CK2, PKC, and PI3K inhibitors would reduce both HO activity and neuronal vulnerability to hemoglobin in murine cortical cultures. Oxidative cell injury was quantified by LDH release and malondialdehyde assays. HO activity was assessed by carbon monoxide assay. Consistent with prior observations, treating primary cortical cultures with hemoglobin for 16h resulted in release of approximately half of neuronal LDH and a seven-fold increase in malondialdehyde. Both endpoints were significantly reduced by the CK2 inhibitors 4,5,6,7-tetrabromobenzotriazole (TBB) and 2-dimethyl-amino-4,5,6,7-tetrabromo-1H-benzimidazole (DMAT), and by the PKC inhibitor GF109203X; the PI3K inhibitors LY294002 and wortmannin had no effect. None of these inhibitors altered basal HO activity. The 1.9-fold activity increase observed after hemoglobin treatment was largely prevented by LY294002 and LY303511, a structural analog of LY294002 that does not inhibit PI3K activity. It was not reduced by wortmannin, TBB or GF109203X. These results suggest that the protective effect of CK2 and PKC inhibitors in this model is not dependent on reduction in HO activity. In this culture system that expresses both HO-1 and HO-2, HO activity does not appear to be primarily regulated by the PKC/CK2 or PI3K pathways.

Altered plasma proteome during an early phase of peritonitis-induced sepsis

Sepsis is a systemic response to infection commonly found in critically ill patients and is associated with multi-organ failure and high mortality rate. Its pathophysiology and molecular mechanisms are complicated and remain poorly understood. In the present study, we performed a proteomics investigation to characterize early host responses to sepsis as determined by an altered plasma proteome in a porcine model of peritonitis-induced sepsis, which simulated several clinical characteristics of human sepsis syndrome. Haemodynamics, oxygen exchange, inflammatory responses, oxidative and nitrosative stress, and other laboratory parameters were closely monitored. Plasma samples were obtained from seven pigs before and 12 h after the induction of sepsis, and plasma proteins were resolved with two-dimensional gel electrophoresis (n=7 gels/group; before being compared with during sepsis). The resolved proteins were stained with the SYPRO Ruby fluorescence dye and subjected to quantitative and comparative analyses. From approx. 1500 protein spots visualized in each gel, levels of 36 protein spots were significantly altered in the plasma of animals with sepsis (sepsis/basal ratios or degrees of change ranged from 0.07 to 21.24). Q-TOF (quadrupole–time-of-flight) MS and MS/MS (tandem MS) identified 30 protein forms representing 22 unique proteins whose plasma levels were increased, whereas six forms of five unique proteins were significantly decreased during sepsis. The proteomic results could be related to the clinical features of this animal model, as most of these altered proteins have important roles in inflammatory responses and some of them play roles in oxidative and nitrosative stress. In conclusion, these findings may lead to a better understanding of the pathophysiology and molecular mechanisms underlying the sepsis syndrome.