Hemopexin: structure, function, and regulation

Infused wild-type macrophages reside and self-renew in the liver to rescue the hemolysis and anemia of Hmox1-deficient mice

Heme oxygenase 1 (HMOX1), the inducible enzyme that catabolizes the degradation of heme into biliverdin, iron, and carbon monoxide, plays an essential role in the clearance of senescent and damaged red blood cells, systemic iron homeostasis, erythropoiesis, vascular hemostasis, and oxidative and inflammatory stress responses. In humans, HMOX1 deficiency causes a rare and lethal disease, characterized by severe anemia, intravascular hemolysis, as well as vascular and tissue damage. Hmox1 knockout (KO) mice recapitulated the phenotypes of HMOX1-deficiency patients and could be rescued by bone marrow (BM) transplantation that engrafted donor's hematopoietic stem cells into the recipient animals after myeloablation. To find better therapy and elucidate the contribution of macrophages to the pathogenesis of HMOX1-deficiency disease, we infused wild-type (WT) macrophages into Hmox1 KO mice. Results showed that WT macrophages engrafted and proliferated in the livers of Hmox1 KO mice, which corrected the microcytic anemia, rescued the intravascular hemolysis, restored iron homeostasis, eliminated kidney iron overload and tissue damage, and provided long-term protection. These results showed that a single macrophage infusion delivered a long-term curative effect in Hmox1 KO mice, obviating the need for BM transplantation, and suggested that the HMOX1 disease stems mainly from the loss of viable reticuloendothelial macrophages. Our work provides new insights into the etiology of HMOX1 deficiency and demonstrates the potential of infusion of WT macrophages to prevent disease in patients with HMOX1 deficiency and potentially other macrophage-related diseases.

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.

Characterization of the interactions of chemically-modified therapeutic nucleic acids with plasma proteins using a fluorescence polarization assay

Interactions of chemically modified nucleic acid therapeutics with plasma proteins play an important role in facilitating distribution from the injection site to peripheral tissues by reducing renal clearance. Despite the importance of these interactions, analytical methods that can characterize binding constants with individual plasma proteins in a reliable and high throughput manner are not easily available. We developed a fluorescence polarization (FP) based assay and measured binding constants for the 25 most abundant human plasma proteins with phosphorothioate (PS) modified antisense oligonucleotides (ASOs). We evaluated the influence of sequence, sugar modifications, and PS content on ASO interactions with several abundant human plasma proteins and determined the effect of salt and pH on these interactions. PS ASOs were found to associate predominantly with albumin and histidine-rich glycoprotein (HRG) in mouse and human plasma by size-exclusion chromatography. In contrast, PS ASOs associate predominantly with HRG in monkey plasma because of higher concentrations of this protein in monkeys. Finally, plasma proteins capable of binding PS ASOs in human plasma were confirmed by employing affinity chromatography and proteomics. Our results indicate distinct differences in contributions from the PS backbone, nucleobase composition and oligonucleotide flexibility to protein binding.

Heme Catabolic Pathway in Inflammation and Immune Disorders

In recent years, the heme catabolic pathway is considered to play an important regulatory role in cell protection, apoptosis, inflammation, and other physiological and pathological processes. An appropriate amount of heme forms the basic elements of various life activities, while when released in large quantities, it can induce toxicity by mediating oxidative stress and inflammation. Heme oxygenase (HO) -1 can catabolize free heme into carbon monoxide (CO), ferrous iron, and biliverdin (BV)/bilirubin (BR). The diverse functions of these metabolites in immune systems are fascinating. Decades work shows that administration of degradation products of heme such as CO and BV/BR exerts protective activities in systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), multiple sclerosis (MS) and other immune disorders. This review elaborates the molecular and biochemical characterization of heme catabolic pathway, discusses the signal transduction and immunomodulatory mechanism in inflammation and summarizes the promising therapeutic strategies based on this pathway in inflammatory and immune disorders.

Slow-twitch skeletal muscle defects accompany cardiac dysfunction in transgenic mice with a mutation in the myosin regulatory light chain

Myosin light chain 2 ( MYL2) gene encodes the myosin regulatory light chain (RLC) simultaneously in heart ventricles and in slow-twitch skeletal muscle. Using transgenic mice with cardiac-specific expression of the human R58Q-RLC mutant, we sought to determine whether the hypertrophic cardiomyopathy phenotype observed in papillary muscles (PMs) of R58Q mice is also manifested in slow-twitch soleus (SOL) muscles. Skinned SOL muscles and ventricular PMs of R58Q animals exhibited lower contractile force that was not observed in the fast-twitch extensor digitorum longus muscles of R58Q vs. wild-type-RLC mice, but mutant animals did not display gross muscle weakness in vivo. Consistent with SOL muscle abnormalities in R58Q vs. wild-type mice, myosin ATPase staining revealed a decreased proportion of fiber type I/type II only in SOL muscles but not in the extensor digitorum longus muscles. The similarities between SOL muscles and PMs of R58Q mice were further supported by quantitative proteomics. Differential regulation of proteins involved in energy metabolism, cell-cell interactions, and protein-protein signaling was concurrently observed in the hearts and SOL muscles of R58Q mice. In summary, even though R58Q expression was restricted to the heart of mice, functional similarities were clearly observed between the hearts and slow-twitch skeletal muscle, suggesting that MYL2 mutated models of hypertrophic cardiomyopathy may be useful research tools to study the molecular, structural, and energetic mechanisms of cardioskeletal myopathy associated with myosin RLC.-Kazmierczak, K., Liang, J., Yuan, C.-C., Yadav, S., Sitbon, Y. H., Walz, K., Ma, W., Irving, T. C., Cheah, J. X., Gomes, A. V., Szczesna-Cordary, D. Slow-twitch skeletal muscle defects accompany cardiac dysfunction in transgenic mice with a mutation in the myosin regulatory light chain.

Mass spectrometry-based analysis of cerebrospinal fluid from arthritis patients-immune-related candidate proteins affected by TNF blocking treatment

Background

Signs of inflammation in cerebrospinal fluid (CSF) of rheumatoid arthritis patients correlate positively with fatigue, a central nervous system (CNS)-related symptom that can be partially suppressed by TNF blockade. This suggests a possible role for CNS inflammation in arthritis that may be affected by TNF blockade. We therefore investigated the effects of TNF blockade on the arthritis CSF proteome and how candidate proteins related to clinical measures of disease activity and inflammation.

Methods

Mass spectrometry-based quantitative proteomic analysis was performed on CSF from seven polyarthritis patients before and during infliximab treatment. Treatment-associated proteins were identified using univariate (Wilcoxon signed rank test) and multivariate (partial least squares discriminant analysis (PLS-DA)) strategies. Relations between selected candidate proteins and clinical measures were investigated using the Spearman correlations. Additionally, selected proteins were cross-referenced to other studies investigating human CSF in a thorough literature search to ensure feasibility of our results.

Results

Univariate analysis of arthritis CSF proteome revealed a decrease of 35 proteins, predominantly involved in inflammatory processes, following TNF blockade. Seven candidate proteins, Contactin-1 (CNTN1), fibrinogen gamma chain (FGG), hemopexin (HPX), cell adhesion molecule-3 (CADM3), alpha-1B-glycoprotein (A1BG), complement factor B (CFB), and beta-2-microglobulin (B2M), were selected for further studies based on identification by both univariate and multivariate analyses and reported detection in human CSF and known associations to arthritis. Decreased levels of FGG and CFB in CSF after treatment showed strong correlations with both erythrocyte sedimentation rate and disability scores, while CNTN1 and CADM3 were associated with pain.

Conclusion

Several immune-related proteins in the CSF of arthritis patients decreased during TNF blockade, including FGG and CFB that both correlated strongly with systemic inflammation. Our findings stress that also intrathecal inflammatory pathways are related to arthritis symptoms and may be affected by TNF blockade.

Electronic supplementary material

The online version of this article (10.1186/s13075-019-1846-6) contains supplementary material, which is available to authorized users.

Plasma Protein Pattern Correlates With Pain Intensity and Psychological Distress in Women With Chronic Widespread Pain

Objectives: Although generalized muscle pain, tiredness, anxiety, and depression are commonly present among chronic widespread pain (CWP) patients, the molecular mechanisms behind CWP are not fully elucidated. Moreover, the lack of biomarkers often makes diagnosis and treatment problematic. In this study, we investigated the correlation between pain intensity, psychological distress, and plasma proteins among CWP patients and controls (CON). Methods: The plasma proteome of CWP (n = 15) and CON (n = 23) was analyzed using two-dimensional gel electrophoresis. Orthogonal Partial Least Square analysis (OPLS) was used to determine proteins associated with pain intensity (numeric rating scale) in CWP and psychological distress (Hospital and Depression Scale, HADS) in CWP and CON. Significant proteins were identified by MALDI-TOF and tandem MS. Results: In CWP, pain intensity was associated with plasma proteins mostly involved in metabolic and immunity processes (e.g., kininogen-1, fibrinogen gamma chain, and ceruloplasmin), and psychological distress was associated with plasma proteins related to immunity response, iron ion, and lipid metabolism (e.g., complement factor B, complement C1r subcomponent, hemopexin, and clusterin). Discussion: This study suggests that different plasma protein patterns are associated with different pain intensity and psychological distress in CWP. Proteins belonging to the coagulation cascade and immunity processes showed strong associations to each clinical outcome. Using the plasma proteome profile of CWP to study potential biomarker candidates provides a snapshot of ongoing systemic mechanisms in CWP.

HST-MRM-MS: A Novel High-Sample-Throughput Multiple Reaction Monitoring Mass Spectrometric Method for Multiplex Absolute Quantitation of Hepatocellular Carcinoma Serum Biomarker

Absolute quantification of clinical biomarkers by mass spectrometry (MS) has been challenged due to low sample-throughput of current multiple reaction monitoring (MRM) methods. For this problem to be overcome, in this work, a novel high-sample-throughput multiple reaction monitoring mass spectrometric (HST-MRM-MS) quantification approach is developed to achieve simultaneous quantification of 24 samples. Briefly, triplex dimethyl reagents (L, M, and H) and eight-plex iTRAQ reagents were used to label the N- and C-termini of the Lys C-digested peptides, respectively. The triplex dimethyl labeling produces three coelute peaks in MRM traces, and the iTRAQ labeling produces eight peaks in MS2, resulting in 24 (3×8) channels in a single experiment. HST-MRM-MS has shown good accuracy ( R² > 0.98 for absolute quantification), reproducibility (RSD < 15%), and linearity (2-3 orders of magnitude). Moreover, the novel method has been successfully applied in quantifying serum biomarkers in hepatocellular carcinoma (HCC)-related serum samples. In conclusion, HST-MRM-MS is an accurate, high-sample-throughput, and broadly applicable MS-based absolute quantification method.

The Diversity of Mammalian Hemoproteins and Microbial Heme Scavengers Is Shaped by an Arms Race for Iron Piracy

Iron is an essential micronutrient for most living species. In mammals, hemoglobin (Hb) stores more than two thirds of the body's iron content. In the bloodstream, haptoglobin (Hp) and hemopexin (Hpx) sequester free Hb or heme. Pathogenic microorganisms usually acquire iron from their hosts and have evolved complex systems of iron piracy to circumvent nutritional immunity. Herein, we performed an evolutionary analysis of genes coding for mammalian heme-binding proteins and heme-scavengers in pathogen species. The underlying hypothesis is that these molecules are engaged in a molecular arms race. We show that positive selection drove the evolution of mammalian Hb and Hpx. Positively selected sites in Hb are located at the interaction surface with Neisseria meningitidis heme scavenger HpuA and with Staphylococcus aureus iron-regulated surface determinant B (IsdB). In turn, positively selected sites in HpuA and IsdB are located in the flexible protein regions that contact Hb. A residue in Hb (S45H) was also selected on the Caprinae branch. This site stabilizes the interaction with Trypanosoma brucei hemoglobin-haptoglobin (HbHp) receptor (TbHpHbR), a molecule that also mediates trypanosome lytic factor (TLF) entry. In TbHpHbR, positive selection drove the evolution of a variant (L210S) which allows evasion from TLF but reduces affinity for HbHp. Finally, selected sites in Hpx are located at the interaction surface with the Haemophilus influenzae hemophore HxuA, which in turn displays fast evolving sites at the Hpx-binding interface. These results shed light into host-pathogens conflicts and establish the importance of nutritional immunity as an evolutionary force.

Serum Proteomic Study of Women With Obsessive-Compulsive Disorder, Washing Subtype

Introduction

Many genetic studies are conducted on Obsessive-Compulsive Disorder (OCD). however, a high-throughput examination of proteome profile of this severe disease has not been performed yet.

Methods

Here, the proteomic study of OCD patients' serum samples was conducted by the application of Two-Dimensional Electrophoresis (2DE) followed by Mass Spectrometry (MALDI-TOF-TOF).

Results

A total of 240 protein spots were detected and among them, five significant differentially expressed protein spots with the fold change of ≥1.5 were considered for further evaluations. These proteins include IGKC, GC, HPX, and two isoforms of HP. While IGKC and HP show down-regulation, GC and HPX indicate up-regulation. Moreover, a validation study of overall HP levels in patients' serum via nephelometric quantification confirmed the lower levels of this protein in the serum of OCD patients. Additionally, enrichment analysis and validation test revealed that inflammation is one of most dominant processes in OCD.

Conclusion

It is suggested that these candidate proteins and their underlying processes (especially, inflammation) may be linked to OCD pathophysiology and can promise a clinical use after extensive validation studies.

Proteomics of the Rat Myocardium during Development of Type 2 Diabetes Mellitus Reveals Progressive Alterations in Major Metabolic Pathways

Congestive heart failure and poor clinical outcome after myocardial infarction are known complications in patients with type-2 diabetes mellitus (T2DM). Protein alterations may be involved in the mechanisms underlying these disarrays in the diabetic heart. Here we map proteins involved in intracellular metabolic pathways in the Zucker diabetic fatty rat heart as T2DM develops using MS based proteomics. The prediabetic state only induced minor pathway changes, whereas onset and late T2DM caused pronounced perturbations. Two actin-associated proteins, ARPC2 and TPM3, were up-regulated at the prediabetic state indicating increased actin dynamics. All differentially regulated proteins involved in fatty acid metabolism, both peroxisomal and mitochondrial, were up-regulated at late T2DM, whereas enzymes of branched chain amino acid degradation were all down-regulated. At both onset and late T2DM, two members of the serine protease inhibitor superfamily, SERPINA3K and SERPINA3L, were down-regulated. Furthermore, we found alterations in proteins involved in clearance of advanced glycation end-products and lipotoxicity, DCXR and CBR1, at both onset and late T2DM. These proteins deserve elucidation with regard to their role in T2DM pathogenesis and their respective role in the deterioration of the diabetic heart. Data are available via ProteomeXchange with identifiers PXD009538, PXD009554, and PXD009555.

Multiplexed Isobaric Tag-Based Profiling of Seven Murine Tissues Following In Vivo Nicotine Treatment Using a Minimalistic Proteomics Strategy

Nicotine is a major addictive compound in tobacco and a component of smoking-related products, such as e-cigarettes. Once internalized, nicotine can perturb many cellular pathways and can induce alterations in proteins across different cell types; however, the mechanisms thereof remain undetermined. The authors hypothesize that both tissue-specific and global protein abundance alterations result from nicotine exposure. Presented here is the first proteomic profiling of multiple tissues from mice treated orally with nicotine. Proteins extracted from seven tissues (brain, heart, kidney, liver, lung, pancreas, and spleen) from treated (n = 5) and untreated control (n = 5) mice are assembled into a TMT10-plex experiment. A minimalistic proteomics strategy is employed using TMT reagents efficiently and centrifugation-based reversed-phase columns to streamline sample preparation. Combined, over 11 000 non-redundant proteins from over 138 000 different peptides are quantified in seven TMT10-plex experiments. Between 7 and 126 proteins are significantly altered in tissues from nicotine-exposed mice, 11 which are altered in two or more tissues. Our data showcase the vast extent of nicotine exposure across murine tissue.

Cryopreservation and egg yolk medium alter the proteome of ram spermatozoa

Cryopreservation causes significant lethal and sub-lethal damage to spermatozoa. In order to improve freezing outcomes, a comprehensive understanding of sub-lethal damage is required. Cryopreservation induced changes to sperm proteins have been investigated in several species, but few have employed currently available state of the art, data independent acquisition mass spectrometry (MS) methods. We used the SWATH LC-MS method to quantitatively profile proteomic changes to ram spermatozoa following exposure to egg yolk and cryopreservation. Egg yolk contributed 15 proteins to spermatozoa, including vitellogenins, apolipoproteins and complement component C3. Cryopreservation significantly altered the abundance of 51 proteins. Overall, 27 proteins increased (e.g. SERPINB1, FER) and 24 proteins decreased (e.g. CCT subunits, CSNK1G2, TOM1L1) in frozen thawed ram spermatozoa, compared to fresh spermatozoa. Chaperones constituted 20% of the proteins lost from spermatozoa following cryopreservation. These alterations may interfere with both normal cellular functioning and the ability of frozen thawed spermatozoa to appropriately respond to stress. This is the first study to apply SWATH mass spectrometry techniques to characterise proteins contributed by egg yolk based freezing media and to profile cryopreservation induced proteomic changes to ram spermatozoa.

SIGNIFICANCE

This study profiles changes to the sperm proteome induced by exposure to egg yolk based media and the process of cryopreservation, and the biological consequences are discussed.

Identification of warm temperature acclimation-associated 65-kDa protein-2 in Kumgang fat minnow Rhynchocypris kumgangensis

Warm temperature acclimation-associated 65-kDa protein (Wap65) is known to respond to elevated water temperatures and the corresponding gene from several fish species has been cloned. Expression of Wap65 gene is induced by various physiological stresses, such as increase in water temperature, immune response and heavy metal exposure. Two isolated Wap65 genes, Wap65-1 and Wap65-2, display distinct tissue distribution and physiological functions despite high sequence homology. In a previous study, we identified the Wap65-1 gene (kmWap65-1) from Kumgang fat minnow, Rhynchocypris kumgangensis, a small freshwater fish endemic to Korea. The kmWap65-1 gene showed sequence homology with teleost Wap65-1 and mammalian hemopexin, and was highly expressed in response to increased water temperature and bacterial lipopolysaccharide (LPS) exposure. Here, we isolated kmWap65-2 from liver tissue of Kumgang fat minnow and compared the expression profiles of both kmWap65 genes following exposure to various physiological stresses, including thermal changes, bacterial challenge, and environmental toxins. Notably, while kmWap65-1 expression was significantly increased in response to high water temperature, LPS, cadmium, and iron, kmWap65-2 displayed no alterations in expression at high water temperature. However, kmWap65-2 expression was upregulated slightly in response to LPS and highly in presence of copper, bisphenol A, and estradiol. Based on the collective findings, we propose that kmWap65-1 and kmWap65-2 are multifunctional proteins with distinct functions that could serve as useful biomarkers for assessing physiological stress and associated responses in Kumgang fat minnow.

Hemopexin is required for adult neurogenesis in the subventricular zone/olfactory bulb pathway

The neural stem cells (NSCs) of the subventricular zone (SVZ) reside within a specialized niche critical for neurogenesis. Hemopexin, a plasma glycoprotein, has been extensively studied as a heme scavenger at the systemic level. However, little is known about its function in the central nervous system, especially in neurogenesis. In the present study, we demonstrate that deletion of hemopexin leads to neurogenic abnormalities in the SVZ/olfactory bulb (OB) pathway. The lateral ventricle is enlarged in hemopexin-deficient mice, and more apoptosis was observed in Dcx+ cells. Lineage differentiation of NSCs was also inhibited in the SVZ of hemopexin-deficient mice, with more stem cells stayed in an undifferentiated, GFAP+ radial glia-like cell stage. Moreover, hemopexin deletion resulted in impaired neuroblast migration in the rostral migratory stream. Furthermore, exogenous hemopexin protein inhibited apoptosis and promoted the migration and differentiation of cultured NSCs. Finally, immunohistochemical analysis demonstrated that deletion of hemopexin reduced the number of interneurons in the OB. Together, these results suggest a new molecular mechanism for the NSC niche that regulates adult neurogenesis in the SVZ/OB pathway. Our findings may benefit the understanding for olfactory system development.

Homocysteine, folate, hs-C-reactive protein, tumor necrosis factor alpha and inflammatory proteins: are these biomarkers related to nutritional status and cardiovascular risk in childhood-onset systemic lupus erythematosus?

BACKGROUND

Childhood-onset systemic lupus erythematosus (c-SLE) is a chronic autoimmune disease which increases cardiovascular risk factors (CRF) such as elevated homocysteine, TNF-α, and hs-C reactive protein.

METHODS

We evaluated BMI, waist circumference (WC), 24-h recalls, SLEDAI-2 K, SLICC/ACR-DI, serum levels of homocysteine, folate, TNF-α, hs-C reactive protein, lipid profile, proteomic data, and duration of corticosteroid therapy in 19 c-SLE and 38 healthy volunteers. Physiological and anthropometric variables of c-SLE and healthy controls were compared by ANCOVA. k-cluster was used to separate c-SLE into two different groups with the best and the worst metabolic profile according to previous analysis showing some metabolites that were statistically different from controls, such as homocysteine, TNF-α, hs-CRP and folate levels. These two clusters were again compared with the control group regarding nutritional parameters, lipid profile and also proteomic data.

RESULTS

Individuals with c-SLE presented higher BMI, WC, homocysteine, triglycerides, TNF-α, hs-CRP and lower folate levels when compared to controls. We found 10 proteins whose relative abundances were statistically different between control group and lupus clusters with the best (LCBMP) and the worst metabolic profile (LCWMP). A significant positive correlation was found between TNF-α and triglycerides and between hs-CRP and duration of corticosteroid therapy.

CONCLUSION

Cardiovascular disease (CVD) risk parameters were worse in c-SLE. A less protective CVD proteomic profile was found in LCWMP.

Physiological responses of reared sea bream (Sparus aurata Linnaeus, 1758) to an Amyloodinium ocellatum outbreak

Amyloodiniosis represents a major bottleneck for semi-intensive aquaculture production in Southern Europe, causing extremely high mortalities. Amyloodinium ocellatum is a parasitic dinoflagellate that can infest almost all fish, crustacean and bivalves that live within its ecological range. Fish mortalities are usually attributed to anoxia, associated with serious gill hyperplasia, inflammation, haemorrhage and necrosis in heavy infestations; or with osmoregulatory impairment and secondary microbial infections due to severe epithelial damage in mild infestation. However, physiological information about the host responses to A. ocellatum infestation is scarce. In this work, we analysed the proteome of gilthead sea bream (Sparus aurata) plasma and relate it with haematological and immunological indicators, in order to enlighten the different physiological responses when exposed to an A. ocellatum outbreak. Using 2D-DIGE, immunological and haematological analysis and in response to the A. ocellatum contamination we have identified several proteins associated with acute-phase response, inflammation, lipid transport, homoeostasis, and osmoregulation, wound healing, neoplasia and iron transport. Overall, this preliminary study revealed that amyloodiniosis affects some fish functional pathways as revealed by the changes in the plasma proteome of S. aurata, and that the innate immunological system is not activated in the presence of the parasite.

Covalent bonding of heme to protein prevents heme capture by nontypeable Haemophilus influenzae

Nontypeable Haemophilus influenzae (NTHi) are Gram‐negative pathogens that contribute to a variety of diseases, including acute otitis media and chronic obstructive pulmonary disease. As NTHi have an absolute requirement for heme during aerobic growth, these bacteria have to scavenge heme from their human hosts. These heme sources can range from free heme to heme bound to proteins, such as hemoglobin. To test the impact of heme structural factors on heme acquisition by NTHi, we prepared a series of heme sources that systematically vary in heme exposure and covalent binding of heme to peptide/protein and tested the ability of NTHi to use these sources to support growth. Results from this study suggest that NTHi can utilize protein‐associated heme only if it is noncovalently attached to the protein.

Quantitative Proteomics of Cerebrospinal Fluid in Paediatric Pneumococcal Meningitis

Streptococcus pneumoniae is responsible for diseases causing major global public health problems, including meningitis, pneumonia and septicaemia. Despite recent advances in antimicrobial therapy, pneumococcal meningitis remains a life-threatening disease. Furthermore, long-term sequelae are a major concern for survivors. Hence, a better understanding of the processes occurring in the central nervous system is crucial to the development of more effective management strategies. We used mass spectrometry based quantitative proteomics to identify protein changes in cerebrospinal fluid from children with Streptococcus pneumoniae infection, compared with children admitted to hospital with bacterial meningitis symptoms but negative diagnosis. Samples were analysed, by label free proteomics, in two independent cohorts (cohort 1: cases (n = 8) and hospital controls (n = 4); cohort 2: cases (n = 8), hospital controls (n = 8)). Over 200 human proteins were differentially expressed in each cohort, of which 65% were common to both. Proteins involved in the immune response and exosome signalling were significantly enriched in the infected samples. For a subset of proteins derived from the proteome analysis, we corroborated the proteomics data in a third cohort (hospital controls (n = 15), healthy controls (n = 5), cases (n = 20)) by automated quantitative western blotting, with excellent agreement with our proteomics findings. Proteomics data are available via ProteomeXchange with identifier PXD004219.

Comparative proteome analysis of egg yolk plasma proteins during storage

BACKGROUND

Physical changes such as chicken egg white thinning and egg yolk flattening occur during storage, implying a decline in egg quality. To reveal the deteriorative process related to chicken egg internal quality, a comparative proteomic method was used in this study to analyze the alterations in egg yolk plasma proteins at different storage times (0, 20 and 40 days) under an ambient temperature of 22 ± 2 °C.

RESULTS

Using two-dimensional electrophoresis followed by matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry, 33 protein spots representing 12 proteins were identified with significant (P < 0.05) alterations in abundance at different storage times. The proteins that showed significant changes in abundance included serum albumin, vitellogenin fragments, IgY chains, ovalbumin, ovoinhibitor, α₂ -macroglobulin-like protein 1-like, hemopexin, transthyretin, apolipoprotein A-I and β₂ -glycoprotein I precursor. Accelerating degradation for most egg yolk plasma proteins was observed after prolonged storage (from day 20 to day 40).

CONCLUSION

It is likely that the increased degradation of protease inhibitors such as ovoinhibitor and α₂ -macroglobulin-like protein 1-like during prolonged storage lead to an imbalance of protease and antiprotease in egg yolk, which may play a key role in the degradation of egg yolk proteins. These findings will provide an insight into the effects of storage on egg yolk protein changes and give a deeper understanding of the deteriorative process of chicken egg yolk. © 2016 Society of Chemical Industry.

Subventricular zone involvement in Glioblastoma - A proteomic evaluation and clinicoradiological correlation

Glioblastoma multiforme (GBM), the most malignant of all gliomas is characterized by a high degree of heterogeneity and poor response to treatment. The sub-ventricular zone (SVZ) is the major site of neurogenesis in the brain and is rich in neural stem cells. Based on the proximity of the GBM tumors to the SVZ, the tumors can be further classified into SVZ+ and SVZ−. The tumors located in close contact with the SVZ are classified as SVZ+, while the tumors located distantly from the SVZ are classified as SVZ−. To gain an insight into the increased aggressiveness of SVZ+ over SVZ− tumors, we have used proteomics techniques like 2D-DIGE and LC-MS/MS to investigate any possible proteomic differences between the two subtypes. Serum proteomic analysis revealed significant alterations of various acute phase proteins and lipid carrying proteins, while tissue proteomic analysis revealed significant alterations in cytoskeletal, lipid binding, chaperone and cell cycle regulating proteins, which are already known to be associated with disease pathobiology. These findings provide cues to molecular basis behind increased aggressiveness of SVZ+ GBM tumors over SVZ− GBM tumors and plausible therapeutic targets to improve treatment modalities for these highly invasive tumors.

Heme as a Target for Therapeutic Interventions

Heme is a complex of iron and the tetrapyrrole protoporphyrin IX with essential functions in aerobic organisms. Heme is the prosthetic group of hemoproteins such as hemoglobin and myoglobin, which are crucial for reversible oxygen binding and transport. By contrast, high levels of free heme, which may occur in various pathophysiological conditions, are toxic via pro-oxidant, pro-inflammatory and cytotoxic effects. The toxicity of heme plays a major role for the pathogenesis of prototypical hemolytic disorders including sickle cell disease and malaria. Moreover, there is increasing appreciation that detrimental effects of heme may also be critically involved in diseases, which usually are not associated with hemolysis such as severe sepsis and atherosclerosis. In mammalians homeostasis of heme and its potential toxicity are primarily controlled by two physiological systems. First, the scavenger protein hemopexin (Hx) non-covalently binds extracellular free heme with high affinity and attenuates toxicity of heme in plasma. Second, heme oxygenases (HOs), in particular the inducible HO isozyme, HO-1, can provide antioxidant cytoprotection via enzymatic degradation of intracellular heme. This review summarizes current knowledge on the pathophysiological role of heme for various diseases as demonstrated in experimental animal models and in humans. The functional significance of Hx and HOs for the regulation of heme homeostasis is highlighted. Finally, the therapeutic potential of pharmacological strategies that apply Hx and HO-1 in various clinical settings is discussed.

Identification of Novel Chondroprotective Mediators in Resolving Inflammatory Exudates

We hypothesized that exudates collected at the beginning of the resolution phase of inflammation might be enriched for tissue protective molecules; thus an integrated cellular and molecular approach was applied to identify novel chondroprotective bioactions. Exudates were collected 6 h (inflammatory) and 24 h (resolving) following carrageenan-induced pleurisy in rats. The resolving exudate was subjected to gel filtration chromatography followed by proteomics, identifying 61 proteins. Fractions were added to C28/I2 chondrocytes, grown in micromasses, ions with or without IL-1β or osteoarthritic synovial fluids for 48 h. Three proteins were selected from the proteomic analysis, α1-antitrypsin (AAT), hemopexin (HX), and gelsolin (GSN), and tested against catabolic stimulation for their effects on glycosaminoglycan deposition as assessed by Alcian blue staining, and gene expression of key anabolic proteins by real-time PCR. In an in vivo model of inflammatory arthritis, cartilage integrity was determined histologically 48 h after intra-articular injection of AAT or GSN. The resolving exudate displayed protective activities on chondrocytes, using multiple readouts: these effects were retained in low m.w. fractions of the exudate (46.7% increase in glycosaminoglycan deposition; ∼20% upregulation of COL2A1 and aggrecan mRNA expression), which reversed the effect of IL-1β. Exogenous administration of HX, GSN, or AAT abrogated the effects of IL-1β and osteoarthritic synovial fluids on anabolic gene expression and increased glycosaminoglycan deposition. Intra-articular injection of AAT or GSN protected cartilage integrity in mice with inflammatory arthritis. In summary, the strategy for identification of novel chondroprotective activities in resolving exudates identified HX, GSN and AAT as potential leads for new drug discovery programs.

An All-Recombinant Protein-Based Culture System Specifically Identifies Hematopoietic Stem Cell Maintenance Factors

Hematopoietic stem cells (HSCs) are considered one of the most promising therapeutic targets for the treatment of various blood disorders. However, due to difficulties in establishing stable maintenance and expansion of HSCs in vitro, their insufficient supply is a major constraint to transplantation studies. To solve these problems we have developed a fully defined, all-recombinant protein-based culture system. Through this system, we have identified hemopexin (HPX) and interleukin-1α as responsible for HSC maintenance in vitro. Subsequent molecular analysis revealed that HPX reduces intracellular reactive oxygen species levels within cultured HSCs. Furthermore, bone marrow immunostaining and 3D immunohistochemistry revealed that HPX is expressed in non-myelinating Schwann cells, known HSC niche constituents. These results highlight the utility of this fully defined all-recombinant protein-based culture system for reproducible in vitro HSC culture and its potential to contribute to the identification of factors responsible for in vitro maintenance, expansion, and differentiation of stem cell populations.

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Different BSA lots alter how HSCs respond to cytokines

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RSA can replace BSA to provide HSC maintenance culture with minimal variability

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By comparing the protein profiles of “good” and “bad” BSAs, HPX was identified

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HPX reduces HSC intracellular reactive ROS and is expressed by BM Schwann cells

Mapping Atheroprotective Functions and Related Proteins/Lipoproteins in Size Fractionated Human Plasma

HDL has been shown to possess a variety of cardio-protective functions, including removal of excess cholesterol from the periphery, and inhibition of lipoprotein oxidation. It has been proposed that various HDL subparticles exist, each with distinct protein and lipid compositions, which may be responsible for HDL's many functions. We hypothesized that HDL functions will co-migrate with the operational lipoprotein subspecies when separated by gel filtration chromatography. Plasma from 10 healthy male donors was fractionated and the protein composition of the phospholipid containing fractions was analyzed by mass spectrometry (MS). Each fraction was evaluated for its proteomic content as well as its ability to promote cholesterol efflux and protect low density lipoprotein (LDL) from free radical oxidation. For each function, several peaks of activity were identified across the plasma size gradient. Neither cholesterol efflux or LDL antioxidation activity correlated strongly with any single protein across the fractions. However, we identified multiple proteins that had strong correlations (r values >0.7, p < 0.01) with individual peaks of activity. These proteins fell into diverse functional categories, including those traditionally associated with lipid metabolism, as well as alternative complement cascade, innate immunity and clotting cascades and immunoglobulins. Additionally, the phospholipid and cholesterol concentration of the fractions correlated strongly with cholesterol efflux (r = 0.95 and 0.82 respectively), whereas the total protein content of the fractions correlated best with antioxidant activity across all fractions (r = 0.746). Furthermore, two previously postulated subspecies (apoA-I, apoA-II and apoC-1; as well as apoA-I, apoC-I and apoJ) were found to have strong correlations with both cholesterol efflux and antioxidation activity. Up till now, very little has been known about how lipoprotein composition mediates functions like cholesterol efflux and antioxidation.

Physiologic and genetic evidence links hemopexin to triglycerides in mice and humans

BACKGROUND/OBJECTIVES

Elevated triglycerides predict insulin resistance and vascular disease in obesity, but how the inert triglyceride molecule is related to development of metabolic disease is unknown. To pursue novel potential mediators of triglyceride-associated metabolic disease, we used a forward genetics approach involving inbred mice and translated our findings to human subjects.

SUBJECTS/METHODS

Hemopexin (HPX) was identified as a differentially expressed gene within a quantitative trait locus associated with serum triglycerides in an F₁₆ advanced intercross between the LG/J and SM/J strains of mice. Hpx expression was evaluated in both the reproductive fat pads and livers of mice representing three strains, LG/J (n=25), SM/J (n=27) and C57Bl/6J (n=19), on high- and low-fat diets. The effect of altered Hpx expression on adipogenesis was studied in 3T3-L1 cells. Circulating HPX protein along with HPX expression were characterized in subcutaneous white adipose tissue samples obtained from a cohort of metabolically abnormal (n=18) and of metabolically normal (n=24) obese human subjects. We further examined the relationship between HPX and triglycerides in human atherosclerotic plaques (n=18).

RESULTS

HPX expression in mouse adipose tissue, but not in liver, was regulated by dietary fat regardless of genetic background. HPX increased in concert with adipogenesis in 3T3-L1 cells, and disruption of its expression impaired adipocyte differentiation. RNAseq data from the adipose tissue of obese humans showed differential expression of HPX based on metabolic disease status (P<0.05), and circulating HPX levels were correlated with serum triglycerides in these subjects (r=0.33; P=0.03). HPX was also found in an unbiased proteomic screen of human atherosclerotic plaques and shown to display differential abundance based on the extent of disease and triglyceride content (P<0.05).

CONCLUSIONS

Our findings suggest that HPX is associated with triglycerides and provide a framework for understanding mechanisms underlying lipid metabolism and metabolic disease.

Molecular and Cellular Bases of Iron Metabolism in Humans

Iron is a microelement with the most completely studied biological functions. Its wide dissemination in nature and involvement in key metabolic pathways determine the great importance of this metal for uni- and multicellular organisms. The biological role of iron is characterized by its indispensability in cell respiration and various biochemical processes providing normal functioning of cells and organs of the human body. Iron also plays an important role in the generation of free radicals, which under different conditions can be useful or damaging to biomolecules and cells. In the literature, there are many reviews devoted to iron metabolism and its regulation in pro- and eukaryotes. Significant progress has been achieved recently in understanding molecular bases of iron metabolism. The purpose of this review is to systematize available data on mechanisms of iron assimilation, distribution, and elimination from the human body, as well as on its biological importance and on the major iron-containing proteins. The review summarizes recent ideas about iron metabolism. Special attention is paid to mechanisms of iron absorption in the small intestine and to interrelationships of cellular and extracellular pools of this metal in the human body.

Insulin attenuates TNFα-induced hemopexin mRNA: An anti-inflammatory action of insulin in rat H4IIE hepatoma cells

Proinflammatory cytokines, including TNF-α and IL-6, can contribute to insulin resistance. Conversely, insulin has some actions that can be considered anti-inflammatory. Hemopexin is a Class 2 acute phase reactant and control of its transcription is predominantly regulated by IL-6, with TNF-α and IL-1β also inducing hemopexin gene expression. Thus, we asked whether insulin could inhibit the ability of TNF-α to stimulate hemopexin mRNA expression. In cultured rat hepatoma (H4IIE) cells, TNF-α significantly increased hemopexin mRNA accumulation. The TNF-α-induced increase of hemopexin mRNA was dramatically attenuated by insulin, even though TNF-α reduced peak insulin activation of ERK. Thus, even though TNF-α can contribute to insulin resistance, the residual insulin response was still able to counteract TNF-α actions.

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The TNF-α-induced increase of hemopexin mRNA was dramatically attenuated by insulin.

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This occurred even though TNF-α significantly decreased insulin activation of ERK.

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This suggests an additional mechanism for the anti-inflammatory action of insulin.

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Cytokine-induced insulin resistance does not abolish insulin’s anti-inflammatory effect.

Brain iron overload following intracranial haemorrhage

Intracranial haemorrhages, including intracerebral haemorrhage (ICH), intraventricular haemorrhage (IVH) and subarachnoid haemorrhage (SAH), are leading causes of morbidity and mortality worldwide. In addition, haemorrhage contributes to tissue damage in traumatic brain injury (TBI). To date, efforts to treat the long-term consequences of cerebral haemorrhage have been unsatisfactory. Incident rates and mortality have not showed significant improvement in recent years. In terms of secondary damage following haemorrhage, it is becoming increasingly apparent that blood components are of integral importance, with haemoglobin-derived iron playing a major role. However, the damage caused by iron is complex and varied, and therefore, increased investigation into the mechanisms by which iron causes brain injury is required. As ICH, IVH, SAH and TBI are related, this review will discuss the role of iron in each, so that similarities in injury pathologies can be more easily identified. It summarises important components of normal brain iron homeostasis and analyses the existing evidence on iron-related brain injury mechanisms. It further discusses treatment options of particular promise.

Changes in serum proteins after endotoxin administration in healthy and choline-treated calves

BACKGROUND

This study aimed to investigate the possible serum protein changes after endotoxin administration in healthy and choline-treated calves using proteomics. These results are expected to contribute to the understanding of the pathophysiological mechanisms of endotoxemia and the beneficial effect of choline administration in this clinical situation.

METHODS

Healthy-calves (n = 20) were divided into 4 groups: Control, Choline treated (C), Lipopolysaccharide administered (LPS), and LPS + C. Control calves received 0.9 % NaCl injection. Calves in C and LPS + C groups received choline chloride (1 mg/kg/iv). Endotoxin (LPS) was injected (2 μg/kg/iv) to the calves in LPS and LPS + C groups. Serum samples were collected before and after the treatments. Differentially expressed proteins (> 1.5 fold-change relative to controls) were identified by LC-MS/MS.

RESULTS

After LPS administration, 14 proteins increased, and 13 proteins decreased within 48 h as compared to controls. In the LPS group, there were significant increases in serum levels of ragulator complex protein (189-fold) and galectin-3-binding protein (10-fold), but transcription factor MafF and corticosteroid binding globulin were down regulated (≥ 5 fold). As compared with the LPS group, in LPS + C group, fibrinogen gamma-B-chain and antithrombin were up-regulated, while hemopexin and histone H4 were down-regulated. Choline treatment attenuated actin alpha cardiac muscle-1 overexpression after LPS.

CONCLUSIONS

LPS administration produces changes in serum proteins associated with lipid metabolism, immune and inflammatory response, protein binding/transport, cell adhesion, venous thrombosis, cardiac contractility and blood coagulation. The administration of choline is associated with changes in proteins which can be related with its beneficial effect in this clinical situation.

Purified and Recombinant Hemopexin: Protease Activity and Effect on Neutrophil Chemotaxis

Infusion of the heme-binding protein hemopexin has been proposed as a novel approach to decrease heme-induced inflammation in settings of red blood cell breakdown, but questions have been raised as to possible side effects related to protease activity and inhibition of chemotaxis. We evaluated protease activity and effects on chemotaxis of purified plasma hemopexin obtained from multiple sources as well as a novel recombinant fusion protein Fc-hemopexin. Amidolytic assay was performed to measure the protease activity of several plasma-derived hemopexin and recombinant Fc-hemopexin. Hemopexin was added to the human monocyte culture in the presence of lipopolysaccharides (LPS), and also injected into mice intravenously (i.v.) 30 min before inducing neutrophil migration via intraperitoneal (i.p.) injection of thioglycolate. Control groups received the same amount of albumin. Protease activity varied widely between hemopexins. Recombinant Fc-hemopexin bound heme, inhibited the synergy of heme with LPS on tumor necrosis factor (TNF) production from monocytes, and had minor but detectable protease activity. There was no effect of any hemopexin preparation on chemotaxis, and purified hemopexin did not alter the migration of neutrophils into the peritoneal cavity of mice. Heme and LPS synergistically induced the release of LTB4 from human monocytes, and hemopexin blocked this release, as well as chemotaxis of neutrophils in response to activated monocyte supernatants. These results suggest that hemopexin does not directly affect chemotaxis through protease activity, but may decrease heme-driven chemotaxis and secondary inflammation by attenuating the induction of chemoattractants from monocytes. This property could be beneficial in some settings to control potentially damaging inflammation induced by heme.

Heme Synthesis and Acquisition in Bacterial Pathogens

Bacterial pathogens require the iron-containing cofactor heme to cause disease. Heme is essential to the function of hemoproteins, which are involved in energy generation by the electron transport chain, detoxification of host immune effectors, and other processes. During infection, bacterial pathogens must synthesize heme or acquire heme from the host; however, host heme is sequestered in high-affinity hemoproteins. Pathogens have evolved elaborate strategies to acquire heme from host sources, particularly hemoglobin, and both heme acquisition and synthesis are important for pathogenesis. Paradoxically, excess heme is toxic to bacteria and pathogens must rely on heme detoxification strategies. Heme is a key nutrient in the struggle for survival between host and pathogen, and its study has offered significant insight into the molecular mechanisms of bacterial pathogenesis.

Proteomic analysis allows for identifying targets of Yinchenwuling Powder in hyperlipidemic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Yinchenwuling Powder (YCL) is a traditional Chinese medicine formula originated from Synopsis of Golden Chamber, which is effective in positively modulating lipid levels in clinics. In this study, we utilized proteomic technology to identify the therapeutic targets of YCL on hyperlipidemic rats.

METHODS

We established hyperlipidemic model rats and administrated them with different doses of YCL extracts (0.35g/ml, 0.75g/ml and 1.5g/ml). Serum lipid levels were quantified and proteomic analysis was performed on plasma samples at the end of the study. Total plasma proteins were separated by two-dimensional electrophoresis (2-DE), and protein spots with 1.5-fold difference were excised and then analyzed by MALDI-TOF MS. Proteomic results were verified by Western blotting.

RESULTS

The results showed that the serum levels of TC, TG, and LDL-C were significantly decreased, while the HDL-C levels were significantly increased in different doses of YCL treatment groups. After being analyzed by 2-DE and MALDI-TOF MS, 12 proteins were identified. Eight proteins (T-kininogen, C3, C4, C4BPA, Igλ-2 chain C, Mbl2, Hpx and FGL1) were up-regulated in hyperlipidemic model rats, while four proteins (ApoE, ALB, TTR and VDBP) were up-regulated in the control and the YCL-treated rats. Two plasma proteins, ApoE and FGL1, involved in lipid metabolism, were confirmed by western blotting, and the results were consistent with the data from the proteomics results.

CONCLUSIONS

In this experiment, we identified 12 differentially-expressed plasma proteins associated with therapeutic effects of YCL. The functions of those proteins are related with lipid metabolism, blood coagulation, anti-inflammation and substance transport. This study provided a clue for the mechanism that underlies the therapeutic effect of YCL on lipid metabolism.

Red cell DAMPs and inflammation

Intravascular hemolysis, or the destruction of red blood cells in the circulation, can occur in numerous diseases, including the acquired hemolytic anemias, sickle cell disease and β-thalassemia, as well as during some transfusion reactions, preeclampsia and infections, such as those caused by malaria or Clostridium perfringens. Hemolysis results in the release of large quantities of red cell damage-associated molecular patterns (DAMPs) into the circulation, which, if not neutralized by innate protective mechanisms, have the potential to activate multiple inflammatory pathways. One of the major red cell DAMPs, heme, is able to activate converging inflammatory pathways, such as toll-like receptor signaling, neutrophil extracellular trap formation and inflammasome formation, suggesting that this DAMP both activates and amplifies inflammation. Other potent DAMPs that may be released by the erythrocytes upon their rupture include heat shock proteins (Hsp), such as Hsp70, interleukin-33 and Adenosine 5' triphosphate. As such, hemolysis represents a major inflammatory mechanism that potentially contributes to the clinical manifestations that have been associated with the hemolytic diseases, such as pulmonary hypertension and leg ulcers, and likely plays a role in specific complications of sickle cell disease such as endothelial activation, vaso-occlusive processes and tissue injury.

Biomarkers of systemic inflammation in farmers with musculoskeletal disorders; a plasma proteomic study

Background

Farmers have an increased risk for musculoskeletal disorders (MSD) such as osteoarthritis of the hip, low back pain, and neck and upper limb complaints. The underlying mechanisms are not fully understood. Work-related exposures and inflammatory responses might be involved. Our objective was to identify plasma proteins that differentiated farmers with MSD from rural referents.

Methods

Plasma samples from 13 farmers with MSD and rural referents were included in the investigation. Gel based proteomics was used for protein analysis and proteins that differed significantly between the groups were identified by mass spectrometry.

Results

In total, 15 proteins differed significantly between the groups. The levels of leucine-rich alpha-2-glycoprotein, haptoglobin, complement factor B, serotransferrin, one isoform of kininogen, one isoform of alpha-1-antitrypsin, and two isoforms of hemopexin were higher in farmers with MSD than in referents. On the other hand, the levels of alpha-2-HS-glycoprotein, alpha-1B-glycoprotein, vitamin D- binding protein, apolipoprotein A1, antithrombin, one isoform of kininogen, and one isoform of alpha-1-antitrypsin were lower in farmers than in referents. Many of the identified proteins are known to be involved in inflammation.

Conclusions

Farmers with MSD had altered plasma levels of protein biomarkers compared to the referents, indicating that farmers with MSD may be subject to a more systemic inflammation. It is possible that the identified differences of proteins may give clues to the biochemical changes occurring during the development and progression of MSD in farmers, and that one or several of these protein biomarkers might eventually be used to identify and prevent work-related MSD.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-016-1059-y) contains supplementary material, which is available to authorized users.

Proteomic analysis of cardiac response to thermal acclimation in the eurythermal goby fish Gillichthys mirabilis

Cardiac function is thought to play a central role in determining thermal optima and tolerance limits in teleost fishes. Investigating proteomic responses to temperature in cardiac tissues may provide insights into mechanisms supporting the thermal plasticity of cardiac function. Here, we utilized a global proteomic analysis to investigate changes in cardiac protein abundance in response to temperature acclimation (transfer from 13°C to 9, 19 and 26°C) in a eurythermal goby, Gillichthys mirabilis. Proteomic data revealed 122 differentially expressed proteins across acclimation groups, 37 of which were identified using tandem mass-spectrometry. These 37 proteins are involved in energy metabolism, mitochondrial regulation, iron homeostasis, cytoprotection against hypoxia, and cytoskeletal organization. Compared with the 9 and 26°C groups, proteins involved in energy metabolism increased in 19°C-acclimated fish, indicating an overall increase in the capacity for ATP production. Creatine kinase abundance increased in 9°C-acclimated fish, suggesting an important role for the phosphocreatine energy shuttle in cold-acclimated hearts. Both 9 and 26°C fish also increased abundance of hexosaminidase, a protein directly involved in post-hypoxia stress cytoprotection of cardiac tissues. Cytoskeletal restructuring appears to occur in all acclimation groups; however, the most prominent effect was detected in 26°C-acclimated fish, which exhibited significantly increased actin levels. Overall, proteomic analysis of cardiac tissue suggests that the capacity to adjust ATP-generating processes is crucial to the thermal plasticity of cardiac function. Furthermore, G. mirabilis may optimize cellular functions at temperatures near 19°C, which lies within the species' preferred temperature range.

Deletion of the hemopexin or heme oxygenase-2 gene aggravates brain injury following stroma-free hemoglobin-induced intracerebral hemorrhage

Background

Following intracerebral hemorrhage (ICH), red blood cells release massive amounts of toxic heme that causes local brain injury. Hemopexin (Hpx) has the highest binding affinity to heme and participates in its transport, while heme oxygenase 2 (HO2) is the rate-limiting enzyme for the degradation of heme. Microglia are the resident macrophages in the brain; however, the significance and role of HO2 and Hpx on microglial clearance of the toxic heme (iron-protoporphyrin IX) after ICH still remain understudied. Accordingly, we postulated that global deletion of constitutive HO2 or Hpx would lead to worsening of ICH outcomes.

Methods

Intracerebral injection of stroma-free hemoglobin (SFHb) was used in our study to induce ICH. Hpx knockout (Hpx^−/−) or HO2 knockout (HO2^−/−) mice were injected with 10 μL of SFHb in the striatum. After injection, behavioral/functional tests were performed, along with anatomical analyses. Iron deposition and neuronal degeneration were depicted by Perls’ and Fluoro-Jade B staining, respectively. Immunohistochemistry with anti-ionized calcium-binding adapter protein 1 (Iba1) was used to estimate activated microglial cells around the injured site.

Results

This study shows that deleting Hpx or HO2 aggravated SFHb-induced brain injury. Compared to wild-type littermates, larger lesion volumes were observed in Hpx^−/− and HO2^−/− mice, which also bear more degenerating neurons in the peri-lesion area 24 h postinjection. Fewer Iba1-positive microglial cells were detected at the peri-lesion area in Hpx^−/− and HO2^−/− mice, interestingly, which is associated with markedly increased iron-positive microglial cells. Moreover, the Iba1-positive microglial cells increased from 24 to 72 h postinjection and were accompanied with improved neurologic deficits in Hpx^−/− and HO2^−/− mice. These results suggest that Iba1-positive microglial cells could engulf the extracellular SFHb and provide protective effects after ICH. We then treated cultured primary microglial cells with SFHb at low and high concentrations. The results show that microglial cells actively take up the extracellular SFHb. Of interest, we also found that iron overload in microglia significantly reduces the Iba1 expression level and resultantly inhibits microglial phagocytosis.

Conclusions

This study suggests that microglial cells contribute to hemoglobin-heme clearance after ICH; however, the resultant iron overloads in microglia appear to decrease Iba1 expression and to further inhibit microglial phagocytosis.

Gender-specific effects of intrauterine growth restriction on the adipose tissue of adult rats: a proteomic approach

BACKGROUND

Intrauterine growth restriction (IUGR) may program metabolic alterations affecting physiological functions and lead to diseases in later life. The adipose tissue is an important organ influencing energy homeostasis. The present study was aimed at exploring the consequences of IUGR on the retroperitoneal adipose tissue of adult male and female rats, using a proteomic approach.

METHODS AND RESULTS

Pregnant Wistar rats were fed with balanced chow, either ad libitum (control group) or restricted to 50 % of control intake (restricted group) during the whole gestation. The offspring were weaned to ad libitum chow and studied at 4 months of age. Retroperitoneal fat was analyzed by two-dimensional gel electrophoresis followed by mass spectrometry. Both male and female restricted groups had low body weight at birth and at weaning but normal body weight at adulthood. The restricted males had normal fat pads weight and serum glucose levels, with a trend to hyperinsulinemia. The restricted females had increased fat pads weight with normal glucose and insulin levels. The restricted males showed up-regulated levels of proteasome subunit α type 3, branched-chain-amino-acid aminotransferase, elongation 1- alpha 1, fatty acid synthase levels, cytosolic malate dehydrogenase and ATP synthase subunit alpha. These alterations point to increased proteolysis and lipogenesis rates and favoring of ATP generation. The restricted females showed down-regulated levels of L-lactate dehydrogenase perilipin-1, mitochondrial branched-chain alpha-keto acid dehydrogenase E1, and transketolase. These findings suggest impairment of glycemic control, stimulation of lipolysis and inhibition of proteolysis, pentose phosphate pathway and lipogenesis rates. In both genders, several proteins involved in oxidative stress and inflammation were affected, in a pattern compatible with impairment of these responses.

CONCLUSIONS

The proteomic analysis of adipose tissue showed that, although IUGR affected pathways of substrate and energy metabolism in both males and females, important gender differences were evident. While IUGR males displayed alterations pointing to a predisposition to later development of obesity, the alterations observed in IUGR females pointed to a metabolic status of established obesity, in agreement with their increased fat pads mass.

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.

Identifying specific proteins involved in eggshell membrane formation using gene expression analysis and bioinformatics

Background

The avian eggshell membranes surround the egg white and provide a structural foundation for calcification of the eggshell which is essential for avian reproduction; moreover, it is also a natural biomaterial with many potential industrial and biomedical applications. Due to the insoluble and stable nature of the eggshell membrane fibres, their formation and protein constituents remain poorly characterized. The purpose of this study was to identify genes encoding eggshell membrane proteins, particularly those responsible for its structural features, by analyzing the transcriptome of the white isthmus segment of the oviduct, which is the specialized region responsible for the fabrication of the membrane fibres.

Results

The Del-Mar 14 K chicken microarray was used to investigate up-regulated expression of transcripts in the white isthmus (WI) compared with the adjacent magnum (Ma) and uterine (Ut) segments of the hen oviduct. Analysis revealed 135 clones hybridizing to over-expressed transcripts (WI/Ma + WI/Ut), and corresponding to 107 NCBI annotated non-redundant Gallus gallus gene IDs. This combined analysis revealed that the structural proteins highly over-expressed in the white isthmus include collagen X (COL10A1), fibrillin-1 (FBN1) and cysteine rich eggshell membrane protein (CREMP). These results validate previous proteomics studies which have identified collagen X (α-1) and CREMP in soluble eggshell extracts. Genes encoding collagen-processing enzymes such as lysyl oxidase homologs 1, 2 and 3 (LOXL1, LOXL2 and LOXL3), prolyl 4 hydroxylase subunit α-2 and beta polypeptide (P4HA2 and P4HB) as well as peptidyl-prolyl cis-trans isomerase C (PPIC) were also over-expressed. Additionally, genes encoding proteins known to regulate disulfide cross-linking, including sulfhydryl oxidase (QSOX1) and thioredoxin (TXN), were identified which suggests that coordinated up-regulation of genes in the white isthmus is associated with eggshell membrane fibre formation.

Conclusions

The present study has identified genes associated with the processing of collagen, other structural proteins, and disulfide-mediated cross-linking during eggshell membrane formation in the white isthmus. Identification of these genes will provide new insight into eggshell membrane structure and mechanisms of formation that will assist in the development of selection strategies to improve eggshell quality and food safety of the table egg.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-2013-3) contains supplementary material, which is available to authorized users.

Breakdown of albumin and haemalbumin by the cysteine protease interpain A, an albuminase of Prevotella intermedia

BACKGROUND

Prevotella intermedia is a Gram-negative black-pigmenting oral anaerobe associated with periodontitis in humans, and has a haem requirement for growth, survival and virulence. It produces an iron porphyrin-containing pigment comprising monomeric iron (III) protoporphyrin IX (Fe(III)PPIX.OH; haematin). The bacterium expresses a 90-kDa cysteine protease termed interpain A (InpA) which both oxidizes and subsequently degrades haemoglobin, releasing haem. However, it is not known whether the enzyme may play a role in degrading other haem-carrying plasma proteins present in the gingival sulcus or periodontal pocket from which to derive haem. This study evaluated the ability of InpA to degrade apo- and haem-complexed albumin.

RESULTS

Albumin breakdown was examined over a range of pH and in the presence of reducing agent; conditions which prevail in sub- and supra-gingival plaque. InpA digested haemalbumin more efficiently than apoalbumin, especially under reducing conditions at pH 7.5. Under these conditions InpA was able to substantially degrade the albumin component of whole human plasma.

CONCLUSIONS

The data point to InpA as an efficient "albuminase" with the ability to degrade the minor fraction of haem-bound albumin in plasma. InpA may thus contribute significantly to haem acquisition by P. intermedia under conditions of low redox potential and higher pH in the inflamed gingival crevice and diseased periodontal pocket where haem availability is tightly controlled by the host.