Haptoglobin, hemopexin, and related defense pathways-basic science, clinical perspectives, and drug development

Heme- and iron-activated macrophages in sickle cell disease: an updated perspective

PURPOSE OF REVIEW

Sickle cell disease (SCD) is a hereditary blood disorder due to a single-point mutation in the β-globin gene. The ensuing hemoglobin has the tendency to polymerize upon deoxygenation, leading to the typical sickle shape of red blood cells. While the primary pathology of sickle cell disease is a direct consequence of altered red blood cells, emerging evidence highlights the central role of macrophages in mediating hemoglobin scavenging, perpetuating oxidative stress and inflammation, and causing endothelial dysfunction and tissue remodeling.

RECENT FINDINGS

Recent research uncovered the impact of heme and iron overload on macrophage polarization and functions in sickle cell disease, and its implication for chronic inflammation and tissue damage in vital organs such as the liver, spleen, lungs and kidneys. By providing a thorough understanding of the dynamic interactions between macrophages and various cellular components within the sickle cell disease milieu, these studies have laid the foundation for the identification of macrophage-related cellular and molecular mechanisms potentially targetable for therapeutic purposes to attenuate sickle complications.

SUMMARY

This review provides a current update about recent discoveries on heme/iron-activated macrophages in SCD, shedding light on their critical role in disease pathophysiology. Ultimately, it proposes avenues for future research aimed at addressing the relevance of these cells for other sickle complications and at targeting them to mitigate disease morbidity and improve patient outcomes.

Method for quantifying free hemoglobin, distinct from the hemoglobin-haptoglobin complex, in human serum

The measurement of free hemoglobin (free Hb) in blood is crucial for assessing the risk of organ damage in patients with hemolytic diseases. However, the colorimetric method, commonly used in clinical practice, does not distinguish between free Hb and the hemoglobin-haptoglobin complex (Hb-Hp) in the blood, instead reflecting the total Hb level. Although size-exclusion high-performance liquid chromatography (SEC-HPLC) can specifically measure free Hb, its clinical use is limited by long assay times. Here, we developed a novel assay method for the rapid quantification of free Hb in serum, distinguishing it from Hb-Hp, using a latex agglutination immunoturbidimetric assay (LATIA). This method could be used to measure free Hb in sera in the range of 1-100 μg/mL in approximately 15 min using an automatic biochemistry analyzer. Using Hb-spiked serum samples from healthy adults, there was a high correlation with Hb levels determined using the newly developed method and SEC-HPLC, indicating a high specificity for free Hb. This novel assay can be used to monitor levels of free Hb in patients with various hemolytic diseases and to design therapeutic strategies based on measured values. However, further studies are required to assess its clinical performance.

Deciphering the role of endothelial granulocyte macrophage-CSF in chronic inflammation associated with HIV

People with HIV (PWH) experience endothelial dysfunction (ED) that is aggravated by chronic inflammation and microbial translocation across a damaged gut barrier. Although this paradigm is well-described, downstream pathways that terminate in endothelial dysfunction are only partially understood. This study found increased expression of granulocyte macrophage colony stimulating factor (GM-CSF), toll-like receptor-4 (TLR4), and myeloperoxidase in the aortic endothelium of PWH compared to those without HIV. Bacteria-derived lipopolysaccharide (LPS) heightened glucose uptake and induced GM-CSF expression in primary human endothelial cells. Exposure to sodium-glucose cotransporter-2 (SGLT2) inhibitors reduced glucose uptake, GM-CSF release, and ED in LPS-activated endothelial cells ex vivo, and PWH treated with SGLT2 inhibitors for diabetes had significantly lower plasma GM-CSF levels than non-diabetic PWH not on this medication. The findings suggest that microbial products trigger glucose uptake and GM-CSF expression in the endothelium, contributing to localized inflammation in PWH. Modifying this altered state could offer therapeutic benefits.

Therapeutics for sickle cell disease intravascular hemolysis

Sickle cell disease (SCD) is a genetic disorder predominantly affecting individuals of African descent, with a significant global health burden. SCD is characterized by intravascular hemolysis, driven by the polymerization of mutated hemoglobin within red blood cells (RBCs), leading to vascular inflammation, organ damage, and heme toxicity. Clinical manifestations include acute pain crises, hemolytic anemia, and multi-organ dysfunction, imposing substantial morbidity and mortality challenges. Current therapeutic strategies mitigate these complications by increasing the concentration of RBCs with normal hemoglobin via transfusion, inducing fetal hemoglobin, restoring nitric oxide signaling, inhibiting platelet-endothelium interaction, and stabilizing hemoglobin in its oxygenated state. While hydroxyurea and gene therapies show promise, each faces distinct challenges. Hydroxyurea's efficacy varies among patients, and gene therapies, though effective, are limited by issues of accessibility and affordability. An emerging frontier in SCD management involves harnessing endogenous clearance mechanisms for hemolysis products. A recent work by Heggland et al. showed that CD-36-like proteins mediate heme absorption in hematophagous ectoparasite, a type of parasite that feeds on the blood of its host. This discovery underscores the need for further investigation into scavenger receptors (e.g., CD36, SR-BI, SR-BII) for their possible role in heme uptake and detoxification in mammalian species. In this review, we discussed current SCD therapeutics and the specific stages of pathophysiology they target. We identified the limitations of existing treatments and explored potential future developments for novel SCD therapies. Novel therapeutic targets, including heme scavenging pathways, hold the potential for improving outcomes and reducing the global burden of SCD.

Hemoglobin homeostasis in abdominal aortic aneurysm: diagnostic and prognostic potential of hemoglobin/heme and scavenger molecules

BACKGROUND

There is increasing evidence implicating hemoglobin/heme and their scavengers in oxidative stress-mediated pathologies, but information is limited in abdominal aortic aneurysm (AAA).

METHODS AND RESULTS

In this case-control study, we assessed heme/heme-related markers in 142 men with AAA and 279 men with a normal aortic diameter consecutively recruited from an ultrasound screening program in Sweden. Enzyme-linked immunosorbent assays (ELISAs) were used to measure heme oxygenase-1 (HO-1) and hemopexin (Hpx) plasma levels, colorimetric assays for cell-free heme and whole blood hemoglobin (Hb) levels, and droplet digital PCR (ddPCR) and real-time PCR to determine haptoglobin (Hp) (pheno)type and genotype, respectively. Hpx and heme plasma levels at baseline were elevated, while HO-1 levels were lower in men with AAA (p < 0.001) and were significantly associated with AAA prevalence independently of potential confounders. A combination of heme and HO-1 showed the best diagnostic potential based on the area under the curve (AUC): 0.76, sensitivity: 80%, specificity: 48%. Additionally, when previously described inflammatory biomarker interleukin-6 (IL-6), was added to our model it significantly improved the diagnostic value (AUC: 0.87, sensitivity: 80%, specificity: 79%) compared to IL-6 alone (AUC: 0.73, sensitivity: 80%, specificity: 49%). Finally, Hb (positively) and Hpx (negatively) levels at baseline were associated with AAA growth rate (mm/year), and their combination showed the best prognostic value for discriminating fast and slow-growing AAA (AUC: 0.76, sensitivity: 80%, specificity: 62%).

CONCLUSIONS

This study reports the distinct disruption of heme and related markers in both the development and progression of AAA, underscoring their potential in aiding risk stratification and therapeutic strategies.

Navigating Hemolysis, Hemoglobin Toxicity, and Its Renal Implications in Cardiac Surgery

Cardiopulmonary bypass–induced hemolysis is linked to acute kidney injury in cardiac surgery. Emerging therapies targeting cell-free hemoglobin (CFHb), like haptoglobin, nitric oxide (NO), and antioxidants, show promise in reducing kidney injury, highlighting the need for further research.

Quantitative proteomic analysis and replacement therapy identifies haptoglobin as a therapeutic target in a murine model of SLE-associated diffuse alveolar hemorrhage

Background

Diffuse alveolar hemorrhage (DAH) is a catastrophic clinical syndrome and one of the manifestations of pulmonary involvement in systemic lupus erythematosus (SLE), which is characterized by hemoptysis, diffuse pulmonary infiltrates, and respiratory failure. However, the treatment options for DAH remain limited, and DAH-related studies are needed to explore more effective therapeutic directions for better disease management and improved prognosis.

Methods

This study utilized the pristane-induced DAH murine model to mimic the pathological process of DAH in patients with SLE. Proteomic analysis was conducted to detect differentially expressed proteins (DEPs) in the plasma of surviving and non-surviving mice, followed by an analysis of biological functions and pathways. The most significant DEP was then confirmed in the plasma of SLE patients with or without DAH and DAH murine model with or without fatal outcomes. Finally, the therapeutic value of haptoglobin (Hp) replacement was validated in a DAH murine model through lung histopathology, RT-qPCR, and survival analysis.

Results

This study identified 178 DEPs, with 118 upregulated and 60 downregulated DEPs in the non-survival group. Within a set of notable Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, complement and coagulation cascades emerged as the most prominent pathway associated with the process of DAH. Later, the most significant DEP, haptoglobin (Hp), was confirmed to exhibit a significant decrease in the plasma of individuals with SLE-DAH and DAH murine model with poor outcomes by the ELISA test. Finally, compared with the control group, the severity of DAH in the Hp treatment group was alleviated significantly, as manifested by the decreased levels of pro-inflammatory cytokines (IL-6 and TNF-α), increased levels of anti-inflammatory cytokines (IL-10 and TGF-β), and decreased mortality.

Conclusion

A reduction in plasma Hp levels was observed in SLE-DAH, and the replacement therapy with Hp could alleviate pulmonary hemorrhage and reduce mortality in DAH mice. This study identified Hp as a potential biomarker for its clinical diagnosis and a direction for treatment.

The Possible Effects of Galectin-3 on Mechanisms of Renal and Hepatocellular Injury Induced by Intravascular Hemolysis

Intravascular hemolysis is a central feature of congenital and acquired hemolytic anemias, complement disorders, infectious diseases, and toxemias. Massive and/or chronic hemolysis is followed by the induction of inflammation, very often with severe damage of organs, which enhances the morbidity and mortality of hemolytic diseases. Galectin-3 (Gal-3) is a β-galactoside-binding lectin that modulates the functions of many immune cells, thus affecting inflammatory processes. Gal-3 is also one of the main regulators of fibrosis. The role of Gal-3 in the development of different kidney and liver diseases and the potential of therapeutic Gal-3 inhibition have been demonstrated. Therefore, the objective of this review is to discuss the possible effects of Gal-3 on the process of kidney and liver damage induced by intravascular hemolysis, as well as to shed light on the potential therapeutic targeting of Gal-3 in intravascular hemolysis.

Ginsenoside Rh2 Regulates the Calcium/ROS/CK1α/MLKL Pathway to Promote Premature Eryptosis and Hemolysis in Red Blood Cells

Ginsenoside Rh2 (GRh2) exhibits significant potential as an anticancer agent; however, progress in developing chemotherapeutic drugs is impeded by their toxicity toward off-target tissues. Specifically, anemia caused by chemotherapy is a debilitating side effect and can be caused by red blood cell (RBC) hemolysis and eryptosis. Cells were exposed to GRh2 in the antitumor range and hemolytic and eryptotic markers were examined under different experimental conditions using photometric and cytofluorimetric methods. GRh2 caused Ca2+-independent, concentration-responsive hemolysis in addition to disrupted ion trafficking with K+ and Cl- leakage. Significant increases in cells positive for annexin-V-fluorescein isothiocyanate, Fluo4, and 2,7-dichlorofluorescein were noted upon GRh2 treatment coupled with a decrease in forward scatter and acetylcholinesterase activity. Importantly, the cytotoxic effects of GRh2 were mitigated by ascorbic acid and by blocking casein kinase 1α (CK1α) and mixed lineage kinase domain-like (MLKL) signaling. In contrast, Ca2+ omission, inhibition of KCl efflux, and isosmotic sucrose aggravated GRh2-induced RBC death. In whole blood, GRh2 selectively targeted reticulocytes and lymphocytes. Altogether, this study identified novel mechanisms underlying GRh2-induced RBC death involving Ca2+ buildup, loss of membrane phospholipid asymmetry and cellular volume, anticholinesterase activity, and oxidative stress. These findings shed light on the hematologic toxicity of GRh2 which is crucial for optimizing its utilization in cancer treatment.

How are Trypanosoma brucei receptors protected from host antibody-mediated attack?

Trypanosoma brucei is the causal agent of African Trypanosomiasis in humans and other animals. It maintains a long-term infection through an antigenic variation based population survival strategy. To proliferate in a mammal, T. brucei acquires iron and haem through the receptor mediated uptake of host transferrin and haptoglobin-hemoglobin respectively. The receptors are exposed to host antibodies but this does not lead to clearance of the infection. Here we discuss how the trypanosome avoids this fate in the context of recent findings on the structure and cell biology of the receptors.

An oral carbon monoxide-releasing molecule protects against acute hyperhemolysis in sickle cell disease

ABSTRACT

Acute hyperhemolysis is a severe life-threatening complication in patients with sickle cell disease (SCD) that may occur during delayed hemolytic transfusion reaction (DHTR), or vaso-occlusive crises associated with multiorgan failure. Here, we developed in vitro and in vivo animal models to mimic endothelial damage during the early phase of hyperhemolysis in SCD. We then used the carbon monoxide (CO)-releasing molecule CORM-401 and examined its effects against endothelial activation, damage, and inflammation inflicted by hemolysates containing red blood cell membrane-derived particles. The in vitro results revealed that CORM-401: (1) prevented the upregulation of relevant proinflammatory and proadhesion markers controlled by the NF-κB enhancer of activated B cells, and (2) abolished the expression of the nuclear factor erythroid-2-related factor 2 (Nrf2) that regulates the inducible antioxidant cell machinery. We also show in SCD mice that CORM-401 protects against hemolysate-induced acute damage of target organs such as the lung, liver, and kidney through modulation of NF-κB proinflammatory and Nrf2 antioxidant pathways. Our data demonstrate the efficacy of CORM-401 as a novel therapeutic agent to counteract hemolysate-induced organ damage during hyperhemolysis in SCD. This approach might be considered as possible preventive treatment in high-risk situations such as patients with SCD with history of DHTR.

Unlocking the link between haptoglobin polymorphism and noninfectious human diseases: insights and implications

Haptoglobin (Hp) is a polymorphic protein that was initially described as a hemoglobin (Hb)-binding protein. The major functions of Hp are to scavenge Hb, prevent iron loss, and prevent heme-based oxidation. Hp regulates angiogenesis, nitric oxide homeostasis, immune responses, and prostaglandin synthesis. Genetic polymorphisms in the Hp gene give rise to different phenotypes, including Hp 1-1, Hp 2-1, and Hp 2-2. Extensive research has been conducted to investigate the association between Hp polymorphisms and several medical conditions including cardiovascular disease, inflammatory bowel disease, cancer, transplantation, and hemoglobinopathies. Generally, the Hp 2-2 phenotype is associated with increased disease risk and poor outcomes. Over the years, the Hp 2 allele has spread under genetic pressures. Individuals with the Hp 2-2 phenotype generally exhibit lower levels of CD163 expression in macrophages. The decreased expression of CD163 may be associated with the poor antioxidant capacity in the serum of subjects carrying the Hp 2-2 phenotype. However, the Hp 1-1 phenotype may confer protection in some cases. The Hp1 allele has strong antioxidant, anti-inflammatory, and immunomodulatory properties. It is important to note that the benefits of the Hp1 allele may vary depending on genetic and environmental factors as well as the specific disease or condition under consideration. Therefore, the Hp1 allele may not necessarily confer advantages in all situations, and its effects may be context-dependent. This review highlights the current understanding of the role of Hp polymorphisms in cardiovascular disease, inflammatory bowel disease, cancer, transplantation, hemoglobinopathies, and polyuria.

Evaluation of haematological parameters in haemolytic anaemia caused by tick-borne pathogens in grazing cattle

BACKGROUND

No tick-borne pathogens (TBPs) causing haemolytic anaemia in cattle have been reported, except Theileria orientalis and complete blood count (CBC) profile is the only haematological parameter to determine the severity of regenerative haemolytic anaemia.

OBJECTIVES

To identify the causative agents of TBP-induced haemolytic anaemia and determine haematological parameters that indicate haemolytic anaemia in grazing cattle.

METHODS

Eighty-two Korean indigenous cattle (Hanwoo) were divided into two groups: grazing (n = 67) and indoor (n = 15) groups. CBC and serum biochemistry were performed. PCR was conducted using whole blood-extracted DNA to investigate the prevalence of TBPs.

RESULTS

TBP-induced haemolytic anaemia was observed in the grazing group. In grazing cattle, co-infection (43.3%, 29/67) was most frequently detected, followed by T. orientalis (37.6%, 25/67) and Anaplasma phagocytophilum infections (1.5%, 1/67). In indoor cattle, only co-infection (20%, 3/15) was identified. Grazing cattle exhibited regenerative haemolytic anaemia with marked monocytosis, mild neutropenia, and thrombocytopenia. According to grazing frequency, the 1st-time grazing group had more severe anaemia than the 2nd-time grazing group. Elevations in indirect bilirubin and L-lactate due to haemolytic anaemia were identified, and correlations with the respective markers were determined in co-infected grazing cattle.

CONCLUSIONS

Quantitative evaluation of haematocrit, mean corpuscular volume, and reticulocytes (markers of regenerative haemolytic anaemia in cattle) was performed for the first time. Our results show that, in addition to T. orientalis, A. phagocytophilum is strongly associated with anaemia. The correlation between haemolytic anaemia severity and haematological parameters (indirect bilirubin, reticulocytes, and L-lactate) was confirmed.

Toxic side-effects of diaspirin cross-linked human hemoglobin are attenuated by the apohemoglobin-haptoglobin complex

Alpha-alpha diaspirin-crosslinked human hemoglobin (DCLHb or ααHb) was a promising early generation red blood cell (RBC) substitute. The DCLHb was developed through a collaborative effort between the United States Army and Baxter Healthcare. The core design feature underlying its development was chemical stabilization of the tetrameric structure of hemoglobin (Hb) to prevent Hb intravascular dimerization and extravasation. DCLHb was developed to resuscitate warfighters on the battlefield, who suffered from life-threatening blood loss. However, extensive research revealed toxic side effects associated with the use of DCLHb that contributed to high mortality rates in clinical trials. This study explores whether scavenging Hb and heme via the apohemoglobin-haptoglobin (apoHb-Hp) complex can reduce DCLHb associated toxicity. Awake Golden Syrian hamsters were equipped with a window chamber model to characterize the microcirculation. Each group was first infused with either Lactated Ringer's or apoHb-Hp followed by a hypovolemic infusion of 10% of the animal's blood volume of DCLHb. Our results indicated that animals pretreated with apoHb-Hb exhibited improved microhemodynamics vs the group pretreated with Lactated Ringer's. While systemic acute inflammation was observed regardless of the treatment group, apoHb-Hp pretreatment lessened those effects with a marked reduction in IL-6 levels in the heart and kidneys compared to the control group. Taken together, this study demonstrated that utilizing a Hb and heme scavenger protein complex significantly reduces the microvasculature effects of ααHb, paving the way for improved HBOC formulations. Future apoHb-Hp dose optimization studies may identify a dose that can completely neutralize DCLHb toxicity.

Inflammatory liver diseases and susceptibility to sepsis

Patients with inflammatory liver diseases, particularly alcohol-associated liver disease and metabolic dysfunction-associated fatty liver disease (MAFLD), have higher incidence of infections and mortality rate due to sepsis. The current focus in the development of drugs for MAFLD is the resolution of non-alcoholic steatohepatitis and prevention of progression to cirrhosis. In patients with cirrhosis or alcoholic hepatitis, sepsis is a major cause of death. As the metabolic center and a key immune tissue, liver is the guardian, modifier, and target of sepsis. Septic patients with liver dysfunction have the highest mortality rate compared with other organ dysfunctions. In addition to maintaining metabolic homeostasis, the liver produces and secretes hepatokines and acute phase proteins (APPs) essential in tissue protection, immunomodulation, and coagulation. Inflammatory liver diseases cause profound metabolic disorder and impairment of energy metabolism, liver regeneration, and production/secretion of APPs and hepatokines. Herein, the author reviews the roles of (1) disorders in the metabolism of glucose, fatty acids, ketone bodies, and amino acids as well as the clearance of ammonia and lactate in the pathogenesis of inflammatory liver diseases and sepsis; (2) cytokines/chemokines in inflammatory liver diseases and sepsis; (3) APPs and hepatokines in the protection against tissue injury and infections; and (4) major nuclear receptors/signaling pathways underlying the metabolic disorders and tissue injuries as well as the major drug targets for inflammatory liver diseases and sepsis. Approaches that focus on the liver dysfunction and regeneration will not only treat inflammatory liver diseases but also prevent the development of severe infections and sepsis.

Hemopexin reverses activation of lung eIF2α and decreases mitochondrial injury in chlorine-exposed mice

We assessed the mechanisms by which nonencapsulated heme, released in the plasma of mice after exposure to chlorine (Cl2) gas, resulted in the initiation and propagation of acute lung injury. We exposed adult male and female C57BL/6 mice to Cl2 (500 ppm for 30 min), returned them to room air, and injected them intramuscularly with either human hemopexin (hHPX; 5 µg/g BW in 50-µL saline) or vehicle at 1 h post-exposure. Upon return to room air, Cl2-exposed mice, injected with vehicle, developed respiratory acidosis, increased concentrations of plasma proteins in the alveolar space, lung mitochondrial DNA injury, increased levels of free plasma heme, and major alterations of their lung proteome. hHPX injection mice mitigated the onset and development of lung and mitochondrial injury and the increase of plasma heme, reversed the Cl2-induced changes in 83 of 237 proteins in the lung proteome at 24 h post-exposure, and improved survival at 15 days post-exposure. Systems biology analysis of the lung global proteomics data showed that hHPX reversed changes in a number of key pathways including elF2 signaling, verified by Western blotting measurements. Recombinant human hemopexin, generated in tobacco plants, injected at 1 h post-Cl2 exposure, was equally effective in reversing acute lung and mtDNA injury. The results of this study offer new insights as to the mechanisms by which exposure to Cl2 results in acute lung injury and the therapeutic effects of hemopexin.NEW & NOTEWORTHY Herein, we demonstrate that exposure of mice to chlorine gas causes significant changes in the lung proteome 24 h post-exposure. Systems biology analysis of the proteomic data is consistent with damage to mitochondria and activation of eIF2, the master regulator of transcription and protein translation. Post-exposure injection of hemopexin, which scavenges free heme, attenuated mtDNA injury, eIF2α phosphorylation, decreased lung injury, and increased survival.

Multi-Omics Approaches for Liver Reveal the Thromboprophylaxis Mechanism of Aspirin Eugenol Ester in Rat Thrombosis Model

Aspirin eugenol ester (AEE) is a novel medicinal compound synthesized by esterifying aspirin with eugenol using the pro-drug principle. Pharmacological and pharmacodynamic experiments showed that AEE had excellent thromboprophylaxis and inhibition of platelet aggregation. This study aimed to investigate the effect of AEE on the liver of thrombosed rats to reveal its mechanism of thromboprophylaxis. Therefore, a multi-omics approach was used to analyze the liver. Transcriptome results showed 132 differentially expressed genes (DEGs) in the AEE group compared to the model group. Proteome results showed that 159 differentially expressed proteins (DEPs) were identified in the AEE group compared to the model group. Six proteins including fibrinogen alpha chain (Fga), fibrinogen gamma chain (Fgg), fibrinogen beta chain (Fgb), orosomucoid 1 (Orm1), hemopexin (Hpx), and kininogen-2 (Kng2) were selected for parallel reaction monitoring (PRM) analysis. The results showed that the expression of all six proteins was upregulated in the model group compared with the control group. In turn, AEE reversed the upregulation trend of these proteins to some degree. Metabolome results showed that 17 metabolites were upregulated and 38 were downregulated in the model group compared to the control group. AEE could reverse the expression of these metabolites to some degree and make them back to normal levels. The metabolites were mainly involved in metabolic pathways, including linoleic acid metabolism, arachidonic acid metabolism, and the tricarboxylic acid (TCA) cycle. Comprehensive analyses showed that AEE could prevent thrombosis by inhibiting platelet activation, decreasing inflammation, and regulating amino acid and energy metabolism. In conclusion, AEE can have a positive effect on thrombosis-related diseases.

Plasma Proteomic Signature of Endometrial Cancer in Patients with Diabetes

The incidence and mortality of endometrial cancer (EC) have increased in recent years. There is mounting evidence that diabetes may play a role in the greater incidence of EC. The molecular mechanisms of the interaction between type 2 diabetes and EC are not yet clearly understood yet. The present study was undertaken to investigate the plasma proteomics of EC patients with diabetes in comparison to those of EC patients without diabetes. Plasma samples were obtained from age-matched patients (EC diabetic and EC nondiabetic). Untargeted proteomic analysis was carried out using a two-dimensional differential gel electrophoresis coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Of the 33 proteins identified, which significantly differed in the plasma abundance between groups, 17 were upregulated and 16 were downregulated. The majority of the altered proteins are involved in the acute phase reaction, cholesterol metabolism, scavenging of heme from plasma, and plasma lipoprotein assembly and mobilization. α-2-macroglobulin, Ras association domain-containing protein 3, apolipoprotein A-I, α-1B-glycoprotein, and zinc-α-2-glycoprotein were significantly upregulated. The significantly downregulated proteins included haptoglobin, apolipoprotein A-IV, hemopexin, and α-1-antichymotrypsin. The differential expression of proteins found in patients who had EC and diabetes indicated severe disease and a poor prognosis. The protein interaction analysis showed dysregulation of cholesterol metabolism and heme scavenging pathways in these patients.

Factors Influencing Venous Remodeling in the Development of Varicose Veins of the Lower Limbs

One of the early symptoms of chronic venous disease (CVD) is varicose veins (VV) of the lower limbs. There are many etiological environmental factors influencing the development of chronic venous insufficiency (CVI), although genetic factors and family history of the disease play a key role. All these factors induce changes in the hemodynamic in the venous system of the lower limbs leading to blood stasis, hypoxia, inflammation, oxidative stress, proteolytic activity of matrix metalloproteinases (MMPs), changes in microcirculation and, consequently, the remodeling of the venous wall. The aim of this review is to present current knowledge on CVD, including the pathophysiology and mechanisms related to vein wall remodeling. Particular emphasis has been placed on describing the role of inflammation and oxidative stress and the involvement of extracellular hemoglobin as pathogenetic factors of VV. Additionally, active substances used in the treatment of VV were discussed.

An in silico analysis of unsteady flow structures in a microaxial blood pump under a pulsating rotation speed

BACKGROUND AND OBJECTIVE

Ventricular assist devices (VADs) are generally designed to perform continuous flow. However, it has been proven that continuous flow, which is not a physiological hemodynamic state, may cause severe complications such as gastrointestinal bleeding, pulmonary hypertension, and ventricular suction. For these reasons, many pulsating blood pump control strategies have been proposed and have the potential for application in percutaneous ventricular assist devices (pVADs) or microaxial blood pumps. A few cases report extra hemolysis when introducing pulsating speed, while none involve blood pumps. This research's primary purpose is to evaluate the potential hemolysis of pVAD under pulsating flow conditions.

METHODS

First, the pulsating flow state is deduced using a heart failure model and varying speed. The heart model is established according to the pathology state collected from a clinical check. The rotation speed and boundary physical state are set to fit the heart failure model. The computational fluid dynamics (CFD) method with the hemolysis prediction model is performed. Furthermore, we used proper orthogonal decomposition (POD) analysis to reconstruct the flow field and obtain more details about shearing and transporting effects.

RESULTS

(1) As a variable rotational speed was introduced, no significant gain in hemolysis accumulation appeared in pVAD. This is quite different from long-term implantable VADs. (2) Pulsation affects hemolysis mainly through pressure (or normal stress). Variable rotational speed affects hemolysis mainly through flow instability. (3) Variable rotational speed will increase the instability and influence hemolysis by transporting and shearing effects, while the transporting effect is more significant.

CONCLUSIONS

The unsteady flow state will affect the spatial distribution of hemolysis, which should be taken into account during control strategy and impeller shape design.

Key players in the regulation of iron homeostasis at the host-pathogen interface

Iron plays a crucial role in the biochemistry and development of nearly all living organisms. Iron starvation of pathogens during infection is a striking feature utilized by a host to quell infection. In mammals and some other animals, iron is essentially obtained from diet and recycled from erythrocytes. Free iron is cytotoxic and is readily available to invading pathogens. During infection, most pathogens utilize host iron for their survival. Therefore, to ensure limited free iron, the host's natural system denies this metal in a process termed nutritional immunity. In this fierce battle for iron, hosts win over some pathogens, but others have evolved mechanisms to overdrive the host barriers. Production of siderophores, heme iron thievery, and direct binding of transferrin and lactoferrin to bacterial receptors are some of the pathogens' successful strategies which are highlighted in this review. The intricate interplay between hosts and pathogens in iron alteration systems is crucial for understanding host defense mechanisms and pathogen virulence. This review aims to elucidate the current understanding of host and pathogen iron alteration systems and propose future research directions to enhance our knowledge in this field.

Discovery of a haptoglobin glycopeptides biomarker panel for early diagnosis of hepatocellular carcinoma

Background

There is a need for new serum biomarkers for early detection of hepatocellular carcinoma (HCC). Haptoglobin (Hp) N-glycosylation is altered in HCC, but the diagnostic value of site-specific Hp glycobiomarkers is rarely reported. We aimed to determine the site-specific glycosylation profile of Hp for early-stage HCC diagnosis.

Method

Hp glycosylation was analyzed in the plasma of patients with liver diseases (n=57; controls), early-stage HCC (n=50) and late-stage HCC (n=32). Hp phenotype was determined by immunoblotting. Hp was immunoisolated and digested into peptides. N-glycopeptides were identified and quantified using liquid chromatography-mass spectrometry. Cohort samples were compared using Wilcoxon rank-sum (Mann-Whitney U) tests. Diagnostic performance was assessed using receiver operating characteristic (ROC) curves and area under curve (AUC).

Results

Significantly higher fucosylation, branching and sialylation of Hp glycans, and expression of high-mannose glycans, was observed as disease progressed from cirrhosis to early- and late-stage HCC. Several glycopeptides demonstrated high values for early diagnosis of HCC, with an AUC of 93% (n=1), >80% (n=3), >75% (n=13) and >70% (n=11), compared with alpha-fetoprotein (AFP; AUC of 79%). The diagnostic performance of the identified biomarkers was only slightly affected by Hp phenotype.

Conclusion

We identified a panel of Hp glycopeptides that are significantly differentially regulated in early- and late-stage HCC. Some glycobiomarkers exceeded the diagnostic value of AFP (the most commonly used biomarker for HCC diagnosis). Our findings provide evidence that glycobiomarkers can be effective in the diagnosis of early HCC - individually, as a panel of glycopeptides or combined with conventional serological biomarkers.

Impact of Asialoglycoprotein Receptor and Mannose Receptor Deficiency on Murine Plasma N-glycome Profiles

The asialoglycoprotein receptor (ASGPR) and the mannose receptor C-type 1 (MRC1) are well known for their selective recognition and clearance of circulating glycoproteins. Terminal galactose and N-Acetylgalactosamine are recognized by ASGPR, while terminal mannose, fucose, and N-Acetylglucosamine are recognized by MRC1. The effects of ASGPR and MRC1 deficiency on the N-glycosylation of individual circulating proteins have been studied. However, the impact on the homeostasis of the major plasma glycoproteins is debated and their glycosylation has not been mapped with high molecular resolution in this context. Therefore, we evaluated the total plasma N-glycome and plasma proteome of ASGR1 and MRC1 deficient mice. ASGPR deficiency resulted in an increase in O-acetylation of sialic acids accompanied by higher levels of apolipoprotein D, haptoglobin, and vitronectin. MRC1 deficiency decreased fucosylation without affecting the abundance of the major circulating glycoproteins. Our findings confirm that concentrations and N-glycosylation of the major plasma proteins are tightly controlled and further suggest that glycan-binding receptors have redundancy, allowing compensation for the loss of one major clearance receptor.

Circulating Iron in Patients with Sickle Cell Disease Mediates the Release of Neutrophil Extracellular Traps

Introduction

Neutrophils promote chronic inflammation and release neutrophil extracellular traps (NETs) that can drive inflammatory responses. Inflammation influences progression of sickle cell disease (SCD), and a role for NETs has been suggested in the onset of vaso-occlusive crisis (VOC). We aimed to identify factors in the circulation of these patients that provoke NET release, with a focus on triggers associated with hemolysis.

Methods

Paired serum and plasma samples during VOC and steady state of 18 SCD patients (HbSS/HbSβ0-thal and HbSC/HbSβ+-thal) were collected. Cell-free heme, hemopexin, and labile plasma iron have been measured in the plasma samples of the SCD patients. NETs formation by human neutrophils from healthy donors induced by serum of SCD patients was studied using confocal microscopy and staining for extracellular DNA using Sytox, followed by quantification of surface coverage using ImageJ.

Results

Eighteen patients paired samples obtained during VOC and steady state were available (11 HbSS/HbSβ0-thal and 7 HbSC/HbSβ+-thal). We observed high levels of systemic heme and iron, concomitant with low levels of the heme-scavenger hemopexin in sera of patients with SCD, both during VOC and in steady state. In our in vitro experiments, neutrophils released NETs when exposed to sera from SCD patients. The release of NETs was associated with high levels of circulating iron in these sera. Although hemin triggered NET formation in vitro, addition of hemopexin to scavenge heme did not suppress NET release in SCD sera. By contrast, the iron scavengers deferoxamine and apotransferrin attenuated NET formation in a significant proportion of SCD sera.

Discussion

Our results suggest that redox-active iron in the circulation of non-transfusion-dependent SCD patients activates neutrophils to release NETs, and hence, exerts a direct pro-inflammatory effect. Thus, we propose that chelation of iron requires further investigation as a therapeutic strategy in SCD.

Effect of the Fermented Soy Q-CAN® Product on Biomarkers of Inflammation and Oxidation in Adults with Cardiovascular Risk, and Canonical Correlations between the Inflammation Biomarkers and Blood Lipids

Systemic low-grade inflammation plays a key role in the development of cardiovascular disease (CVD) but the process may be modulated by consuming fermented soy foods. Here, we aim to evaluate the effect of a fermented soy powder Q-CAN^® on inflammatory and oxidation biomarkers in subjects with cardiovascular risk. In a randomized crossover trial, 27 adults (mean age ± SD, 51.6 ± 13.5 y) with a mean BMI ± SD of 32.3 ± 7.3 kg/m² consumed 25 g daily of the fermented soy powder or an isoenergic control powder of sprouted brown rice for 12 weeks each. Between-treatment results showed a 12% increase in interleukin-1 receptor agonist (IL-1Ra) in the treatment group, whereas within-treatment results showed 23% and 7% increases in interleukin-6 (IL-6) and total antioxidant status (TAS), respectively. The first canonical correlation coefficient (r = 0.72) between inflammation markers and blood lipids indicated a positive association between high-sensitivity C-reactive protein (hsCRP) and IL-1Ra with LDL-C and a negative association with HDL-C that explained 62% of the variability in the biomarkers. These outcomes suggest that blood lipids and inflammatory markers are highly correlated and that ingestion of the fermented soy powder Q-CAN^® may increase IL-1Ra, IL-6, and TAS in individuals with CVD risk factors.

Macrophage metabolic rewiring improves heme-suppressed efferocytosis and tissue damage in sickle cell disease

Sickle cell disease (SCD) is hallmarked by an underlying chronic inflammatory condition, which is contributed by heme-activated proinflammatory macrophages. Although previous studies addressed heme ability to stimulate macrophage inflammatory skewing through Toll-like receptor4 (TLR4)/reactive oxygen species signaling, how heme alters cell functional properties remains unexplored. Macrophage-mediated immune cell recruitment and apoptotic cell (AC) clearance are relevant in the context of SCD, in which tissue damage, cell apoptosis, and inflammation occur owing to vaso-occlusive episodes, hypoxia, and ischemic injury. Here we show that heme strongly alters macrophage functional response to AC damage by exacerbating immune cell recruitment and impairing cell efferocytic capacity. In SCD, heme-driven excessive leukocyte influx and defective efferocytosis contribute to exacerbated tissue damage and sustained inflammation. Mechanistically, these events depend on heme-mediated activation of TLR4 signaling and suppression of the transcription factor proliferator-activated receptor γ (PPARγ) and its coactivator peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α). These changes reduce efferocytic receptor expression and promote mitochondrial remodeling, resulting in a coordinated functional and metabolic reprogramming of macrophages. Overall, this results in limited AC engulfment, impaired metabolic shift to mitochondrial fatty acid β-oxidation, and, ultimately, reduced secretion of the antiinflammatory cytokines interleukin-4 (IL-4) and IL-10, with consequent inhibition of continual efferocytosis, resolution of inflammation, and tissue repair. We further demonstrate that impaired phagocytic capacity is recapitulated by macrophage exposure to plasma of patients with SCD and improved by hemopexin-mediated heme scavenging, PPARγ agonists, or IL-4 exposure through functional and metabolic macrophage rewiring. Our data indicate that therapeutic improvement of heme-altered macrophage functional properties via heme scavenging or PGC1α/PPARγ modulation significantly ameliorates tissue damage associated with SCD pathophysiology.

Carboxyhemoglobin (COHb): Unavoidable Bystander or Protective Player?

Carbon monoxide (CO) is a cytoprotective endogenous gas that is ubiquitously produced by the stress response enzyme heme-oxygenase. Being a gas, CO rapidly diffuses through tissues and binds to hemoglobin (Hb) increasing carboxyhemoglobin (COHb) levels. COHb can be formed in erythrocytes or in plasma from cell-free Hb. Herein, it is discussed as to whether endogenous COHb is an innocuous and inevitable metabolic waste product or not, and it is hypothesized that COHb has a biological role. In the present review, literature data are presented to support this hypothesis based on two main premises: (i) there is no direct correlation between COHb levels and CO toxicity, and (ii) COHb seems to have a direct cytoprotective and antioxidant role in erythrocytes and in hemorrhagic models in vivo. Moreover, CO is also an antioxidant by generating COHb, which protects against the pro-oxidant damaging effects of cell-free Hb. Up to now, COHb has been considered as a sink for both exogenous and endogenous CO generated during CO intoxication or heme metabolism, respectively. Hallmarking COHb as an important molecule with a biological (and eventually beneficial) role is a turning point in CO biology research, namely in CO intoxication and CO cytoprotection.

Assessment of total and unbound cell-free heme in plasma of patients with sickle cell disease

Intravascular hemolysis results in the release of cell-free hemoglobin and heme in plasma. In sickle cell disease, the fragility of the sickle red blood cell leads to chronic hemolysis, which can contribute to oxidative damage and activation of inflammatory pathways. The scavenger proteins haptoglobin and hemopexin provide pathways to remove hemoglobin and heme, respectively, from the circulation. Heme also intercalates in membranes of blood cells and endothelial cells in the vasculature and associates with other plasma components such as albumin and lipoproteins. Hemopexin has a much higher affinity and can strip heme from the other pools and detoxify plasma from cell-free circulatory heme. However, due to chronic hemolysis, hemopexin is depleted in individuals with sickle cell disease. Thus, cell-free unbound heme is expected to accumulate in plasma. We developed a methodology for the accurate quantification of the fraction of heme, which is pathologically relevant in sickle cell disease, that does not appear to be sequestered to a plasma compartment. Our data show significant variation in the concentration of unbound heme, and rather unexpectedly, the size of the unbound fraction does not correlate to the degree of hemolysis, as measured by the concentration of bound heme. Very high heme concentrations (>150 µM) were obtained in some plasma with unbound concentrations that were several fold lower than in plasma with much lower hemolysis (<50 µM). These findings underscore the long-term effects of chronic hemolysis on the blood components and of the disruption of the essential equilibrium between release of hemoproteins/heme in the circulation and adaptative response of the scavenging/removal mechanisms. Understanding the clinical implications of this loss of response may provide insights into diagnostic and therapeutic targets in patients with sickle cell disease.

Molecular and cellular effects of in vivo chronic intravascular hemolysis and anti-inflammatory therapeutic approaches

Intravascular hemolysis (IVH) occurs in numerous inherited and acquired disorders, including sickle cell disease (SCD), malaria and sepsis. These diseases display unique symptoms, but often share complications, such as vasomotor dysfunction and pulmonary hypertension. Consequently, in vivo models are needed to study the effects of continuous intravascular hemolytic processes, independently of the molecular or extrinsic alteration that leads to erythrocyte destruction. We gave twice-weekly low-dose phenylhydrazine (LDPHZ) to C57BL/6 J mice for 4 weeks, and measured parameters indicative of anemia, hemoglobin-clearance pathways, inflammation and iron turnover, comparing these to those of a murine model of SCD, which displays associated IVH. LDPHZ administration provoked discreet anemia in mice and significant reticulocytosis, in association with hemoglobin/heme-clearance pathway protein depletion. Mice subjected to chronic hemolysis displayed elevated leukocyte counts and plasma levels of interleukin (IL)-1β, TNF-α, IL-6, soluble ICAM-1, endothelin-1 and anti-inflammatory IL-10, closely emulating alterations indicative of systemic inflammatory and endothelial activation in SCD, and confirming chronic IVH in itself as a serious complication. Discreet accelerations in hepatic and splenic iron turnover also occurred in LDPHZ mice, without alterations in liver damage markers. Examining the effects of two therapies on hemolysis-induced inflammation, the administration of hydroxyurea (and to a lesser extent, l-glutamine) significantly abrogated hemolytic inflammation in mice, without apparent inhibition of hemolysis. In conclusion, the isolation of chronic IVH, a common disease mechanism, using this model, may allow the study of hemolysis-specific sequelae at the cellular and systemic level, and the investigation of candidate agents that could potentially counter hemolytic inflammation.

Dysregulation of metalloproteins in ischemic heart disease patients with systolic dysfunction

Ischemic heart disease (IHD) is the leading cause of mortality worldwide. Metalloproteins have been linked to human health and diseases. The molecular functions of metalloproteins in IHD is not well understood and require further exploration. The objective of this study was to find out the role of metalloproteins in the pericardial fluid of IHD patients having normal (EF > 45) and impaired (EF < 45) left ventricular ejection fraction (LVEF). IHD patients were grouped into two categories: LVEF<45 (n = 12) and LVEF >45 (n = 33). Pooled samples of pericardial fluid were fractionated by using ZOOM-isoelectric focusing (IEF) followed by further processing using one-dimensional gel electrophoresis (1D SDS-PAGE) and filter-aided sample preparation (FASP). Tryptic peptides of each fraction and differential bands were then analyzed by nano-LC-ESI-MS/MS. Protein identification was performed through a Mascot search engine using NCBI-Prot and SwissProt databases. A total of 1082 proteins including 154 metalloproteins were identified. In the differential bands, 60 metalloproteins were identified, while 115 metalloproteins were identified in all ZOOM-IEF fractions. Twelve differentially expressed metalloproteins were selected in the intense bands according to their molecular weight (MW) and isoelectric point (pI). The 12 differentially expressed metalloprotein includes ceruloplasmin, Prothrombin, Vitamin K-dependent protein, Fibulin-1, Ribosomal protein S6 kinase alpha-6, nidogen, partial, Serum albumin, Hemopexin, C-reactive protein, Serum amyloid P-component, and Intelectin-1 protein which were all up-regulated while serotransferrin is the only metalloprotein that was down-regulated in impaired (LVEF<45) group. Among the metalloproteins, Zn-binding proteins are 36.5 % followed by Ca-binging 32.2 %, and Fe-binging 12.2 %. KEGG, pathway analysis revealed the association of ceruloplasmin and serotransferrin with the ferroptosis pathway. In conclusion, 154 metalloproteins were identified of them the Zn-binding protein followed by Ca-binding and Fe-binding proteins were the most abundant metalloproteins. The two metalloproteins, the Cu-binding protein ceruloplasmin, and Fe-binding protein serotransferrin are involved in the ferroptosis pathway, an iron-dependent form of regulated cell death that has been linked to cardiac pathology, especially in IHD patients having impaired systolic (LVEF<45) dysfunction. However, further research is required to validate these findings.

Role of Macrophages in Sickle Cell Disease Erythrophagocytosis and Erythropoiesis

Sickle cell disease (SCD) is an inherited blood disorder caused by a β-globin gene point mutation that results in the production of sickle hemoglobin that polymerizes upon deoxygenation, causing the sickling of red blood cells (RBCs). RBC deformation initiates a sequence of events leading to multiple complications, such as hemolytic anemia, vaso-occlusion, chronic inflammation, and tissue damage. Macrophages participate in extravascular hemolysis by removing damaged RBCs, hence preventing the release of free hemoglobin and heme, and triggering inflammation. Upon erythrophagocytosis, macrophages metabolize RBC-derived hemoglobin, activating mechanisms responsible for recycling iron, which is then used for the generation of new RBCs to try to compensate for anemia. In the bone marrow, macrophages can create specialized niches, known as erythroblastic islands (EBIs), which regulate erythropoiesis. Anemia and inflammation present in SCD may trigger mechanisms of stress erythropoiesis, intensifying RBC generation by expanding the number of EBIs in the bone marrow and creating new ones in extramedullary sites. In the current review, we discuss the distinct mechanisms that could induce stress erythropoiesis in SCD, potentially shifting the macrophage phenotype to an inflammatory profile, and changing their supporting role necessary for the proliferation and differentiation of erythroid cells in the disease. The knowledge of the soluble factors, cell surface and intracellular molecules expressed by EBI macrophages that contribute to begin and end the RBC’s lifespan, as well as the understanding of their signaling pathways in SCD, may reveal potential targets to control the pathophysiology of the disease.

Host-Derived Cytotoxic Agents in Chronic Inflammation and Disease Progression

At inflammatory sites, cytotoxic agents are released and generated from invading immune cells and damaged tissue cells. The further fate of the inflammation highly depends on the presence of antagonizing principles that are able to inactivate these host-derived cytotoxic agents. As long as the affected tissues are well equipped with ready-to-use protective mechanisms, no damage by cytotoxic agents occurs and resolution of inflammation is initiated. However, long-lasting and severe immune responses can be associated with the decline, exhaustion, or inactivation of selected antagonizing principles. Hence, cytotoxic agents are only partially inactivated and contribute to damage of yet-unperturbed cells. Consequently, a chronic inflammatory process results. In this vicious circle of permanent cell destruction, not only novel cytotoxic elements but also novel alarmins and antigens are liberated from affected cells. In severe cases, very low protection leads to organ failure, sepsis, and septic shock. In this review, the major classes of host-derived cytotoxic agents (reactive species, oxidized heme proteins and free heme, transition metal ions, serine proteases, matrix metalloproteases, and pro-inflammatory peptides), their corresponding protective principles, and resulting implications on the pathogenesis of diseases are highlighted.

Genomic organization and gene evolution of two warm temperature acclimation proteins (Wap65s) of Micropterus salmoides and their responses to temperature and bacterial/viral infections

Warm temperature acclimation-related 65-kDa proteins (Wap65s) are fish plasma acute-phase glycoproteins homologous to hemopexin with high affinity and clearance for heme. The study characterized Mswap65-1 and Mswap65-2 genes in Micropterus salmoides. Structural analysis showed MsWap65s contained conserved heme-binding sites. MsWap65-1 had a chloride-binding site similar to hemopexin, while MsWap65-2 had an additional calcium-binding site. Phylogenetic and Ka/Ks analysis showed that fish Wap65s were evolutionarily conserved and underwent strong purifying selection. Functional divergence analysis indicated that fish Wap65-2 retained the putative function of ancestral Wap65, while Wap65-1 underwent neofunctional differentiation. QPCR showed Mswap65s were predominantly expressed in liver, but prolonged hyperthermy inhibited Mswap65-2 expression. Mswap65-2 expression was up-regulated in liver and spleen after Nocardia seriolae infection, while Mswap65-1 was down-regulated. MsWap65-2 may be associated with pathogenesis and play potential role in pathogen resistance. LMBV infection resulted in both significant downregulation of Mswap65s were both significantly down-regulated, with differences observed between sexes. We speculated the immune system might suppress expression after viral infection. Exogenous rMsWap65s were prepared, and injection of rMsWap65s alleviated phenylhydrazine-induced hemolysis and inhibited increases in heme, complement C3 and inflammatory symptoms. Our results contribute to an advanced understanding of the functions and mechanisms of MsWap65s in stress resistance.

Teeth with acute apical abscess vs. teeth with chronic apical periodontitis: a quantitative and qualitative proteomic analysis

OBJECTIVE

To quantitatively and qualitatively analyze the proteomic profile of teeth with acute apical abscesses (AAA) compared with teeth with chronic apical periodontitis (CAP) and to correlate the expression of detected human proteins with their main biological functions.

MATERIALS AND METHODS

Samples were obtained from root canals of 9 patients diagnosed with AAA and 9 with CAP. Samples were analyzed by reversed-phase liquid chromatography coupled to mass spectrometry. Label-free quantitative proteomic analysis was performed by Protein Lynx Global Service software. Differences in protein expression were calculated using the t-test (p < 0.05).

RESULTS

In total, 246 human proteins were identified from all samples. Proteins exclusively found in the AAA group were mainly associated with the immunoinflammatory response and oxidative stress response. In the quantitative analysis, 17 proteins were upregulated (p < 0.05) in the AAA group, including alpha-1-acid glycoprotein, hemopexin, fibrinogen gamma chain, and immunoglobulin. Additionally, 61 proteins were downregulated (p < 0.05), comprising cathepsin G, moesin, gelsolin, and transketolase. Most of the proteins were from the extracellular matrix, cytoplasm, and nucleus.

CONCLUSIONS

The common proteins between the groups were mainly associated with the immune response at both expression levels. Upregulated proteins mostly belonged to the acute-phase proteins, while the downregulated proteins were associated with DNA/RNA regulation and repair, and structural function.

CLINICAL RELEVANCE

The host response is directly related to the development of apical abscesses. Thus, understanding the behavior of human proteins against the endodontic pathogens involved in this condition might contribute to the study of new approaches related to the treatment of this disease.

Increases in serum carbonylated protein levels of dogs with hypercortisolism

Protein carbonylation is an irreversible and degenerative modification that can be used to evaluate oxidative stress caused by glucocorticoids. In this study, we focused on protein carbonylation in dogs with hypercortisolism (HC). Sera samples were collected from 14 dogs diagnosed with HC and treated with trilostane, 12 dogs with inflammatory diseases (disease control group), and eight clinically healthy dogs. When the carbonylated protein levels were detected by the immunoblot analysis, one band of approximately 40 kDa was predominantly increased in the dogs with HC. The band was identified as haptoglobin using the liquid chromatography tandem mass spectrometry method. Furthermore, haptoglobin immune reactivity was higher in the dogs with HC. Although the average protein carbonylation level of the HC group was not significantly different from that of the other groups, the carbonylation level was significantly higher for the poorly controlled HC cases than for the well-controlled HC group. Additionally, the primary culture of canine hepatocytes was used to clarify the direct effect of glucocorticoids on protein carbonylation in dog livers. Both the carbonylated protein and haptoglobin clearly increased after 72 h. These findings suggest that haptoglobin and its carbonylated form are increased with canine HC, and that the protein carbonylation ratio and/or haptoglobin level could be related to disease management. These factors could be useful as biomarkers for an oxidative stress reaction, at least in the liver, and for treatment monitoring of HC.

Genome-wide identification of antisense lncRNAs and their association with susceptibility to Flavobacterium psychrophilum in rainbow trout

Eukaryotic genomes encode long noncoding natural antisense transcripts (lncNATs) that have been increasingly recognized as regulatory members of gene expression. Recently, we identified a few antisense transcripts correlating in expression with immune-related genes. However, a systematic genome-wide analysis of lncNATs in rainbow trout is lacking. This study used 134 RNA-Seq datasets from five different projects to identify antisense transcripts. A total of 13,503 lncNATs were identified genome-wide. About 75% of lncNATs showed multiple exons compared to 36.5% of the intergenic lncRNAs. RNA-Seq datasets from resistant, control, and susceptible rainbow trout genetic lines with significant differences in survival rate following Flavobacterium psychrophilum (Fp) infection were analyzed to investigate the potential role of the lncNATs during infection. Twenty-four pairwise comparisons between the different genetic lines, infectious status, and time points revealed 581 differentially expressed (DE) lncNATs and 179 differentially used exons (DUEs). Most of the DE lncNATs strongly and positively correlated in expression with their corresponding sense transcripts across 24 RNA-Seq datasets. LncNATs complementary to genes related to immunity, muscle contraction, proteolysis, and iron/heme metabolism were DE following infection. LncNATs complementary to hemolysis-related genes were DE in the resistant fish compared to susceptible fish on day 5 post-infection, suggesting enhanced clearance of free hemoglobin (Hb) and heme and increased erythropoiesis. LncNATs complementary to hepcidin, a master negative regulator of the plasma iron concentration, were the most downregulated lncNATs on day 5 of bacterial infection in the resistant fish. Ninety-four DE lncNAT, including five complementary to hepcidin, are located within 26 QTL regions previously identified in association with bacterial cold water disease (BCWD) in rainbow trout. Collectively, lncNATs are involved in the molecular architecture of fish immunity and should be further investigated for potential applications in genomic selection and genetic manipulation in aquaculture.

Hemopexin accumulates in kidneys and worsens acute kidney injury by causing hemoglobin deposition and exacerbation of iron toxicity in proximal tubules

Hemopexin, a heme scavenging protein, accumulates in the kidneys during acute kidney injury (AKI). However, the function of this accumulated hemopexin in the kidney is unclear. In both the cisplatin-induced and the unilateral kidney ischemia-reperfusion injury models of AKI, we found accumulation of hemoglobin and hemopexin in the kidneys localized to the proximal tubules. Next, hemopexin wild-type and knockout mice were compared in both AKI models and hemopexin wild type mice had significantly worse kidney injury. Furthermore, there was increased kidney expression of kidney injury molecule-1 (a biomarker of AKI) and heme oxygenase-1 (an indicator of oxidative stress) in hemopexin wild type compared with knockout mice in both models of AKI. Next, the interaction of hemopexin and hemoglobin in vitro was investigated using cultured proximal tubular cells. Co-incubation of hemopexin with hemoglobin resulted in hemoglobin deposition and exaggerated hemoglobin-induced injury. Deferoxamine, an iron chelator, and ferrostatin-1, a ferroptosis inhibitor, inhibited this deleterious effect of hemoglobin and hemopexin in proximal tubular cells, implicating iron toxicity in the mechanism of hemopexin mediated injury. Furthermore, the protective effect of deferoxamine in cisplatin-induced AKI was apparent in hemopexin wild type, but not in hemopexin knockout mice, further implicating hemopexin as a mediator of iron toxicity in AKI. Thus, our findings demonstrate that hemopexin accumulates in the kidneys and worsens kidney injury in AKI by increasing hemoglobin deposition on proximal tubular cells to exaggerate hemoglobin-induced cell injury.

The Importance of Dietary Antioxidants on Oxidative Stress, Meat and Milk Production, and Their Preservative Aspects in Farm Animals: Antioxidant Action, Animal Health, and Product Quality-Invited Review

The biological effects of oxidative stress and associated free radicals on farm animal performance, productivity, and product quality may be managed via dietary interventions-specifically, the provision of feeds, supplements, and forages rich in antioxidants. To optimize this approach, it is important first to understand the development of free radicals and their contributions to oxidative stress in tissue systems of farm animals or the human body. The interactions between prooxidants and antioxidants will impact redox homeostasis and, therefore, the well-being of farm animals. The impact of free radical formation on the oxidation of lipids, proteins, DNA, and biologically important macromolecules will likewise impact animal performance, meat and milk quality, nutritional value, and longevity. Dietary antioxidants, endogenous antioxidants, and metal-binding proteins contribute to the 'antioxidant defenses' that control free radical formation within the biological systems. Different bioactive compounds of varying antioxidant potential and bio-accessibility may be sourced from tailored feeding systems. Informed and successful provision of dietary antioxidants can help alleviate oxidative stress. However, knowledge pertaining to farm animals, their unique biological systems, and the applications of novel feeds, specialized forages, bioactive compounds, etc., must be established. This review summarized current research to direct future studies towards more effective controls for free radical formation/oxidative stress in farm animals so that productivity and quality of meat and milk can be optimized.

Vascular Aging and Damage in Patients with Iron Metabolism Disorders

Vascular aging is a physiological, multifactorial process that involves every type of vessel, from large arteries to microcirculation. This manifests itself as impaired vasomotor function, altered secretory phenotype, deteriorated intercellular transport function, structural remodeling, and aggravated barrier function between the blood and the vascular smooth muscle layer. Iron disorders, particularly iron overload, may lead to oxidative stress and, among other effects, vascular aging. The elevated transferrin saturation and serum iron levels observed in iron overload lead to the formation of a non-transferrin-bound iron (NTBI) fraction with high pro-oxidant activity. NTBI can induce the production of reactive oxygen species (ROS), which induce lipid peroxidation and mediate iron-related damage as the elements of oxidative stress in many tissues, including heart and vessels' mitochondria. However, the available data make it difficult to precisely determine the impact of iron metabolism disorders on vascular aging; therefore, the relationship requires further investigation. Our study aims to present the current state of knowledge on vascular aging in patients with deteriorated iron metabolism.

Sickle Cell Disease in Children and Adolescents: A Review of the Historical, Clinical, and Public Health Perspective of Sub-Saharan Africa and Beyond

Sickle cell disease (SCD) is an umbrella term for a group of life-long debilitating autosomal recessive disorders that are caused by a single-point mutation (Glu→Val) that results in polymerization of hemoglobin (Hb) and reversible sickle-shape deformation of erythrocytes. This leads to increased hemolysis of erythrocytes and microvascular occlusion, ischemia-reperfusion injury, and tissue infarction, ultimately causing multisystem end-organ complications. Sickle cell anemia (HbSS) is the most common and most severe genotype of SCD, followed by HbSC, HbSβ 0thalassemia, HbSβ+thalassemia, and rare and benign genotypes. Clinical manifestations of SCD occur early in life, are variable, and are modified by several genetic and environmental factors. Nearly 500 children with SCD continue to die prematurely every day, due to delayed diagnosis and/or lack of access to comprehensive care in sub-Saharan Africa (SSA), a trend that needs to be urgently reversed. Despite proven efficacy in developed countries, newborn screening programs are not universal in SSA. This calls for a consolidated effort to make this possible, through the use of rapid, accurate, and cheap point-of-care test kits which require minimal training. For almost two decades, hydroxyurea (hydroxycarbamide), a century-old drug, was the only disease-modifying therapy approved by the U.S. Food and Drug Administration. Recently, the list expanded to L-glutamine, crizanlizumab, and voxelotor, with several promising novel therapies in the pipeline. Despite its several limitations, hematopoietic stem cell transplant (HSCT) remains the only curative intervention for SCD. Meanwhile, recent advances in gene therapy trials offer a glimpse of hope for the near future, although its use maybe limited to developed countries for several decades.

Babesia microti-induced fulminant sepsis in an immunocompromised host: A case report and the case-specific literature review

Babesia microti is an obligate intra-erythrocytic parasite transmitted by infected ticks. B. microti is a eukaryote much larger than prokaryotic microbes and more similar to human hosts in their biochemistry and metabolism. Moreover, Babesia spp. possess various immune evasion mechanisms leading to persistent and sometimes life-threatening diseases in immunocompromised hosts. Chronic lymphocytic leukemia (CLL) is the most prevalent adult B-cell malignancy, and a small percentage of CLL transforms into aggressive lymphomas. CLL also causes immune dysfunction due to the over-expansion of immature and ineffective B-cells. When our patient with indolent CLL presented with anemia, pancytopenia, and splenomegaly, all his healthcare providers presumptively assumed a malignant transformation of CLL. However, these are also the signs and symptoms of babesiosis. Herein, we report a case where B. microti infection was presumed as a malignant transformation of CLL and narrowly avoided a devastating outcome. Although the patient developed fulminant sepsis, he finally received the correct diagnosis and treatment. Unfortunately, the disease recrudesced twice. Each time, it became more difficult to control the infection. We describe the clinical course of the case and discuss the case-specific literature review. This report highlights the importance of differential diagnoses ruling out infections which include babesiosis, prior to initiating the treatment of B-cell malignancy.

Intravascular hemolysis leads to exaggerated corpus cavernosum relaxation: Implication for priapism in sickle cell disease

Patients with sickle cell disease (SCD) display priapism. Clinical studies have shown a strong positive correlation between priapism and high levels of intravascular hemolysis in men with SCD. However, there are no experimental studies that show that intravascular hemolysis promotes alterations in erectile function. Therefore, we aimed to evaluate the corpus cavernosum smooth muscle relaxant function in a murine model that displays intravascular hemolysis induced by phenylhydrazine (PHZ), as well as the role of intravascular hemolysis in increasing the stress oxidative in the penis. Corpus cavernosum strips were dissected free and placed in organ baths. Acetylcholine and electrical field stimulation (EFS)-induced corpus cavernosum relaxations in vitro were obtained. Increased corpus cavernosum relaxant responses to acetylcholine and EFS were observed in the PHZ group. Protein expression of heme oxygenase-1 increased in the corpus cavernosum of the PHZ group, but PDE5 protein expression was not modified. Preincubation with the heme oxygenase inhibitor 1 J completely reversed the increased relaxant responses to acetylcholine and EFS in PHZ mice. Protein expression of NADPH oxidase subunit gp91phox, 3-nitrotyrosine, and 4-hydroxynonenal increased in the corpus cavernosum of the PHZ group, suggesting a state of oxidative stress. Basal cGMP production was lower in the PHZ group. Our results show that intravascular hemolysis promotes increased corpus cavernosum smooth muscle relaxation associated with increased HO-1 expression, as well as increased oxidative stress associated with upregulation of gp91phox expression. Moreover, our study supports clinical studies that point to a strong positive correlation between priapism and high levels of intravascular hemolysis in men with SCD.

High-Level Expression of Cell-Surface Signaling System Hxu Enhances Pseudomonas aeruginosa Bloodstream Infection

Bloodstream infections (BSIs) caused by Pseudomonas aeruginosa are associated with a high mortality rate in the clinic. However, the fitness mechanisms responsible for the evolution of virulence factors that facilitate the dissemination of P. aeruginosa to the bloodstream are poorly understood. In this study, a transcriptomic analysis of the BSI-associated P. aeruginosa clinical isolates showed a high-level expression of cell-surface signaling (CSS) system Hxu. Whole-genome sequencing and comparative genomics of these isolates showed that a mutation in rnfE gene was responsible for the elevated expression of the Hxu-CSS pathway. Most importantly, deletion of the hxuIRA gene cluster in a laboratory strain PAO1 reduced its BSI capability while overexpression of the HxuIRA pathway promoted BSI in a murine sepsis model. We further demonstrated that multiple components in the blood plasma, including heme, hemoglobin, the heme-scavenging proteins haptoglobin, and hemopexin, as well as the iron-delivery protein transferrin, could activate the Hxu system. Together, these studies suggested that the Hxu-CSS system was an important signal transduction pathway contributing to the adaptive pathogenesis of P. aeruginosa in BSI.

Heme induces inflammatory injury by directly binding to the complex of myeloid differentiation protein 2 and toll-like receptor 4

Heme, as an essential component of hemoproteins, is a prosthetic co-factor found in many cells, which is essential for physiologically vital oxygen transport. However, extracellular or circulatory heme is cytotoxic and triggers inflammation. Although the proinflammatory role of heme has been reported to be associated with Toll-like receptor 4 (TLR4) signaling, the exact mechanism remains unknown. Here, we show that heme promotes TLR4 signaling and inflammation via directly physically interacting with TLR4 and its adaptor protein myeloid differentiation protein 2 (MD2). Genetic loss of MD2 ameliorates heme-induced inflammation and inflammatory cytokine production in the spleen of MD2 knockout (MD2^-/-) mice. Using mouse macrophage RAW 264.7 cell line, we show that heme induces TLR4 dimerization and MD2/TLR4/MyD88 activation by physically interacting with TLR4 and MD2 in vitro. Genetic loss of MD2 inhibits heme-induced inflammation and MAPK/NF-κB pathway in mouse primary macrophages extracted from MD2^-/- mice. Furthermore, pharmacological inhibition of MD2 by L6H9 ameliorates heme-induced inflammation in macrophages. These findings demonstrate that heme causes inflammation by directly binding to MD2/TLR4 complex, leading to activation of TLR4/MAPK/NF-κB signaling pathway and production of downstream effectors of inflammation.

Erythrophagocytes in hemolytic anemia, wound healing, and cancer

Hemolysis is a ubiquitous pathology defined as premature red blood cell destruction within the circulation or local tissues. One of the most archetypal functions of macrophages is phagocytosis of damaged or extravasated red blood cells, preventing the extracellular release of toxic hemoglobin and heme. Upon erythrophagocytosis, spiking intracellular heme concentrations drive macrophage transformation into erythrophagocytes, leveraging antioxidative and iron recycling capacities to defend against hemolytic stress. This unique phenotype transformation is coordinated by a regulatory network comprising the transcription factors BACH1, SPI-C, NRF2, and ATF1. Erythrophagocytes negatively regulate inflammation and immunity and may modulate disease-specific outcomes in hemolytic anemia, wound healing, atherosclerosis, and cancer. In this opinion article, we outline the known and presumed functions of erythrophagocytes and their implications for therapeutic innovation and research.

The effect of calcium-magnesium mixtures in sol-gel coatings on bone tissue regeneration

Calcium and magnesium are two elements essential for bone structure and metabolism. However, their synergistic or competitive effects on bone regeneration are often overlooked during biomaterial development. We examined the interactions between Ca and Mg in sol-gel coatings doped with mixtures of CaCl₂ (0.5%) and MgCl₂ (0.5, 1, and 1.5%). After physicochemical characterisation, the materials were incubated in vitro with MC3T3-E1 osteoblastic cells and RAW264.7 macrophages, and the protein adsorption was analysed using nLC-MS/MS. The incorporation of the ions did not lead to the formation of crystalline structures and did not affect the sol-gel network cross-linking. The release of the ions did not cause cytotoxic effects at any tested concentration. The proteomic analysis showed that adding the Ca and Mg ions elevated the adsorption of proteins associated with inflammatory response regulation (e.g., ALBU, CLUS, HPT, HPTR, A1AG1 and A1AG2) but decreased the adsorption of immunoglobulins. The CaMg coatings had reduced affinity to proteins associated with coagulation (e.g., FA9, FA10, FA11, FA12) but increased the adsorption of proteins involved in cell adhesion (DSG1, DESP, FBLN1, ZA2G). In vitro assays revealed that the cellular response was affected by changing the concentration of Mg. Moreover, our results show that these differences reflect the changes in the concentrations of both ions in the mix but are not a simple additive effect.

Haptoglobin polymorphism affects its N-glycosylation pattern in serum

•

Polymorphism affects glycosylation pattern of haptoglobin in healthy population.

•

Sample phenotype classification was done based on the number and type of α-chains.

•

Glycoproteomic analyses of haptoglobin were done using enzyme-assisted LC-MS/MS.

•

Significant differences were obseerved in branching, sialylation and fucosylation.

Introduction

Haptoglobin (Hp) is an abundant acute-phase protein secreted mainly by the liver into the bloodstream. There are three Hp protein phenotypes (Hp type 1–1, 2–1, and 2–2), which differ in the number of α- and β-chains, type of α-chain (the β-chain type remains the same in all the Hp phenotypes), and the polymers that they form via disulfide bonds. Hp has four N-glycosylation sites on the β-chain. Glycosylation of Hp has been reported frequently as a potential glycobiomarker for many diseases; however, whether Hp polymorphism affects its glycosylation has not yet been addressed extensively or in depth.

Objectives

This study investigated the differences between the glycosylation patterns of Hp phenotypes using serum from 12 healthy individuals (four for each Hp phenotype).

Method

An efficient method for isolating Hp from serum was established and subsequently the Hp phenotype of each sample was characterized by immunoblotting. Then, LC-MS/MS analysis of isolated Hp after treatment with three exoglycosidases (sialidase, α2-3 neuraminidase, Endo F3) was performed to characterize the glycosylation pattern of Hp for each individual sample.

Results

The data reveal significant differences among the branching, sialylation, and fucosylation of Hp types, documenting the effect of Hp polymorphism on its glycosylation.

Conclusion

Overall, the study suggests that Hp phenotype characterization should be considered during the investigation of Hp glycosylation.