Neutrophil-derived azurocidin cleaves insulin-like growth factor-binding protein-1, -2 and -4

Neutrophil Extracellular Traps Drive Dacryolithiasis

Mucopeptide concretions, previously called dacryoliths, are macroscopic stones that commonly obstruct the lacrimal sac. The mechanism behind dacryolithiasis remains unclear; however, the involvement of various immune cells, including neutrophils, has been confirmed. These findings remain limited, and no information on neutrophil extracellular traps (NETs), essentially involved in the pathogenesis of other lithiases, is available yet. Here, we employ microcomputed tomography, magnetic resonance tomography, histochemistry, mass spectrometry, and enzyme activity analyses to investigate the role of neutrophils and NETs in dacryolithiasis. We classify mucopeptide concretions into three types, with respect to the quantity of cellular and acellular material, polysaccharides, and mucosubstances. We propose the role of neutrophils and NETs within the existing model of gradual formation and growth of mucopeptide concretions, with neutrophils contributing to the initial stages of dacryolithiasis, as they localized on the inner (older) parts of the tissue. As NETs localized on the outer (newer) parts of the tissue, we link their role to the late stages of dacryolithiasis, presumably maintaining the proinflammatory environment and preventing efficient clearance. An abundance of IgG on the surface indicates the involvement of the adaptive immune system later as well. These findings bring new perspectives on dacryolithiasis, in which the innate and adaptive immune system are essentially involved.

Clinical Characterization of the Expression of Insulin-Like Growth Factor Binding Protein 1 and Tumor Immunosuppression Caused by Ferroptosis of Neutrophils in Non-Small Cell Lung Cancer

Purpose

The efficacy of immunotherapy for non-small cell lung cancer (NSCLC) is limited owing to cold tumors and drug resistance. Therefore, it is important to identify the molecular mechanisms underlying immune evasion in NSCLC. Spontaneous ferroptosis of neutrophils has been suggested as a key mechanism of immunosuppression in cancer. Insulin-like growth factor binding protein 1 (IGFBP1) plays an important role in immune infiltration in several cancers. However, the role of IGFBP1 in NSCLC is unknown. Therefore, in this study, we aimed to investigate the association of IGFBP1 mRNA expression with infiltration of myeloid-derived suppressor cells and prognosis in NSCLC.

Patients and Methods

Retrospective RNA-seq data from 990 patients in the Cancer Genome Atlas (TCGA) database were analyzed in relation to patient clinical characteristics. The Timer2 database was used to assess immune infiltration, and the FerrDb V2 database was used to obtain ferroptosis-related genes. Finally, the results were validated by the proteomic analysis of serum samples collected from six patients with NSCLC and six healthy individuals.

Results

IGFBP1 expression was enriched in lung adenocarcinoma samples and positively correlated with the pathological grade of NSCLC. IGFBP1 expression was an independent prognostic factor for the overall survival of patients with NSCLC. In addition, IGFBP1 expression correlated with myeloid-derived suppressor cell infiltration. Notably, Gene Ontology analysis of IGFBP1-related genes revealed that the major molecular functions of their protein products were related to NADP⁺ 1-oxidoreductase activity. Furthermore, expression levels of multiple ferroptosis suppressor genes positively correlated with IGFBP1 expression.

Conclusion

High IGFBP1 expression indicates a poor prognosis in patients with NSCLC, which may be related to tumor immunosuppression caused by neutrophil ferroptosis.

Heart failure subphenotypes based on repeated biomarker measurements are associated with clinical characteristics and adverse events (Bio-SHiFT study)

BACKGROUND

This study aimed to identify heart failure (HF) subphenotypes using 92 repeatedly measured circulating proteins in 250 patients with heart failure with reduced ejection fraction, and to investigate their clinical characteristics and prognosis.

METHODS

Clinical data and blood samples were collected tri-monthly until the primary endpoint (PEP) or censoring occurred, with a maximum of 11 visits. The Olink Cardiovascular III panel was measured in baseline samples and the last two samples before the PEP (in 66 PEP cases), or the last sample before censoring (in 184 PEP-free patients). The PEP comprised cardiovascular death, heart transplantation, Left Ventricular Assist Device implantation, and hospitalization for HF. Cluster analysis was performed on individual biomarker trajectories to identify subphenotypes. Then biomarker profiles and clinical characteristics were investigated, and survival analysis was conducted.

RESULTS

Clustering revealed three clinically diverse subphenotypes. Cluster 3 was older, with a longer duration of, and more advanced HF, and most comorbidities. Cluster 2 showed increasing levels over time of most biomarkers. In cluster 3, there were elevated baseline levels and increasing levels over time of 16 remaining biomarkers. Median follow-up was 2.2 (1.4-2.5) years. Cluster 3 had a significantly poorer prognosis compared to cluster 1 (adjusted event-free survival time ratio 0.25 (95%CI:0.12-0.50), p < 0.001). Repeated measurements clusters showed incremental prognostic value compared to clusters using single measurements, or clinical characteristics only.

CONCLUSIONS

Clustering based on repeated biomarker measurements revealed three clinically diverse subphenotypes, of which one has a significantly worse prognosis, therefore contributing to improved (individualized) prognostication.

IGFBP-1 and IGFBP-2 are associated with a decreased pulse-wave velocity in young, healthy adults

Background and aims

In healthy, young adults we analyzed a panel of cardiovascular disease related proteins in plasma and compared them with the vascular health of the subjects. The aim was to identify proteins with a relationship to the early atherosclerotic process in healthy individuals.

Methods

We employed the proximity extension assay from OLINK proteomics to analyze 92 cardiovascular disease (CVD) related proteins on 833 subjects (men and women, ages 18–26). The women were further divided into an estrogen-using group and non-users. Protein expression was analyzed using principal component analysis (PCA). The following vascular examinations were performed: Pulse-wave velocity (PWV), augmentation index (AIX), carotid-intima media thickness (cIMT).

Results

Three principal components were obtained using PCA to analyze the protein expression. None of the obtained principal components correlated significantly with AIX or cIMT. One of the components, explaining 6% of the total variance of the data, was significantly correlated with PWV. Upon examination of the proteins with the highest factor loadings on this component independently in a multivariable model, adjusting for established CVD risk biomarkers, insulin-like growth factor-binding protein 1 (IGFBP-1) and insulin-like growth factor-binding protein 2 (IGFBP-2) were found to independently, negatively correlate with PWV. Among the established risk factors included in the multivariable model, age was significantly and adversely correlated with all vascular measurements.

Conclusions

In this population of healthy, young adults, groups of CVD related proteins correlate with PWV, but not AIX or cIMT. This group of proteins, of which IGFBP-1 and IGFBP-2 were independently, negatively correlated in a multivariable model with PWV, could have benificial effects on vascular stiffness. The robust association between age and PWV, AIX and cIMT provide insight into the impact of aging on the vasculature, which is detectable even in a population of young, healthy, non-smoking individuals of ages spanning only 8 years.

Supplementary information

The online version contains supplementary material available at 10.1186/s12872-021-01914-w.

Identification of biomarkers for drug-resistant endometriosis using clinical proteomics

Dienogest (DNG), is an effective and widely used progestin used in the treatment of endometriosis, yet clinically, a subset of cases show resistance to DNG treatment. During a previous investigation on the effect of DNG of cytokines and growth factor production, we incidentally found that endometriotic cyst fluid did not demonstrate inhibitory effects to DNG in a subset of cases. To clarify the mechanisms of this resistance to DNG, we performed proteomics analysis to compare the protein expression between DNG-sensitive and resistant cases. Based upon our results, several proteins were extracted that relate to neutrophil granulocyte activation marker (myeloperoxidase, lactotransferrin), inflammation (azurocidin, neutrophil gelatinase-associated lipocalin, etc.), and others biological processes reflecting the clinical environment of the endometriotic cyst. Among these proteins, azurocidin (AZU) is perhaps most interesting one as azurocidin is a protease that cleaves insulin-like growth factor-1 (IGFBP-1) associated with clear cell carcinoma of the ovary. We propose that the proteins extracted in the present study warrant further investigation in their relationship to carcinogenesis of endometrioma.

Nasal mucus proteome and its involvement in allergic rhinitis

Introduction: Nasal mucus is the first line defense barrier against various pathogens including allergens. Proteins in nasal mucus maybe used as biomarkers for diagnosis or future therapeutic strategies. Proteomics opens the possibility to investigate whole human proteomes.

Areas Covered: We aimed to analyze the existing literature on nasal mucus and nasal secretions proteomic approaches especially in allergic rhinitis. A PubMed/Medline search was conducted entering the following keywords and combinations: “nasal mucus”, “nasal lavage fluid,” nasal secretions,” “nasal swabs,” “allergic rhinitis,” ”proteins,” and “proteomics.”

Expert opinion: The majority of studies focus on single proteins or protein groups mainly using ELISA techniques. Four studies met the criteria using mass spectrometry in the analysis of nasal mucus proteomes in rhinologic diseases. In these studies, 7, 35, 267, and 430 proteins were identified, respectively. These four studies are discussed in this review and put in relation to seven other proteomic studies that focus on nasal lavage fluid and nasal secretions obtained by swabs or filter paper. To put it in a nutshell, proteomics facilitates the investigation of the nasal secretome and its role in healthy and diseased state and as potential biomarkers for new diagnostic or therapeutic approaches.

A Promising Candidate: Heparin-Binding Protein Steps onto the Stage of Sepsis Prediction

Sepsis is a systemic inflammatory response syndrome caused by infection. With high morbidity and mortality of this disease, there is a need to find early effective diagnosis and assessment methods to improve the prognosis of patients. Heparin-binding protein (HBP) is a granular protein derived from polynuclear neutrophils. The biosynthetic HBP in neutrophils is rapidly released under the stimulation of bacteria, resulting in increased vascular permeability and edema. It is reasonable to speculate that the HBP in plasma may serve as a novel diagnostic marker for sepsis, bacterial skin infection, acute bacterial meningitis, leptospirosis, protozoan parasites, and even some noncommunicable diseases. It implies that in the detection and diagnosis of sepsis, it will be possible to make relevant diagnosis through this new indicator in the future. In this review, we summarize the typical biological function of HBP and its latest research progress to provide theoretical basis for clinical prediction and diagnosis of sepsis.

The role of neutrophil granule proteins in neuroinflammation and Alzheimer's disease

Neutrophils are the innate immune system’s first line of defense. Neutrophils play a critical role in protecting the host against infectious pathogens, resolving sterile injuries, and mediating inflammatory responses. The granules of neutrophils and their constituent proteins are central to these functions. Although neutrophils may exert a protective role upon acute inflammatory conditions or insults, continued activity of neutrophils in chronic inflammatory diseases can contribute to tissue damage. Neutrophil granule proteins are involved in a number of chronic inflammatory conditions and diseases. However, the functions of these proteins in neuroinflammation and chronic neuroinflammatory diseases, including Alzheimer’s disease (AD), remain to be elucidated. In this review, we discuss recent findings from our lab and others that suggest possible functions for neutrophils and the neutrophil granule proteins, CAP37, neutrophil elastase, and cathepsin G, in neuroinflammation, with an emphasis on AD. These findings reveal that neutrophil granule proteins may exert both neuroprotective and neurotoxic effects. Further research should determine whether neutrophil granule proteins are valid targets for therapeutic interventions in chronic neuroinflammatory diseases.

Bioactive Antimicrobial Peptides as Therapeutics for Corneal Wounds and Infections

Significance: More than 2 million eye injuries and infections occur each year in the United States that leave civilians and military members with reduced or complete vision loss due to the lack of effective therapeutics. Severe ocular injuries and infections occur in varied settings including the home, workplace, and battlefields. In this review, we discuss the potential of developing antimicrobial peptides (AMPs) as therapeutics for the treatment of corneal wounds and infections for which the current treatment options are inadequate.

Recent Advances: Standard-of-care employs the use of fluorescein dye for the diagnosis of ocular defects and is followed by the use of antibiotics and/or steroids to treat the infection and reduce inflammation. Recent advances for treating corneal wounds include the development of amniotic membrane therapies, wound chambers, and drug-loaded hydrogels. In this review, we will discuss an innovative approach using AMPs with the dual effect of promoting corneal wound healing and clearing infections.

Critical Issues: An important aspect of treating ocular injuries is that treatments need to be effective and administered expeditiously. This is especially important for injuries that occur during combat and in individuals who demonstrate delayed wound healing. To overcome gaps in current treatment modalities, bioactive peptides based on naturally occurring cationic antimicrobial proteins are being investigated as new therapeutics.

Future Directions: The development of new therapeutics that can treat ocular infections and promote corneal wound healing, including the healing of persistent corneal epithelial defects, would be of great clinical benefit.

The Role of Neutrophil Proteins on the Amyloid Beta-RAGE Axis

We previously showed an elevated expression of the neutrophil protein, cationic antimicrobial protein of 37kDa (CAP37), in brains of patients with Alzheimer’s disease (AD), suggesting that CAP37 could be involved in AD pathogenesis. The first step in determining how CAP37 might contribute to AD pathogenesis was to identify the receptor through which it induces cell responses. To identify a putative receptor, we performed GAMMA analysis to determine genes that positively correlated with CAP37 in terms of expression. Positive correlations with ligands for the receptor for advanced glycation end products (RAGE) were observed. Additionally, CAP37 expression positively correlated with two other neutrophil proteins, neutrophil elastase and cathepsin G. Enzyme-linked immunosorbent assays (ELISAs) demonstrated an interaction between CAP37, neutrophil elastase, and cathepsin G with RAGE. Amyloid beta 1–42 (Aβ_1–42), a known RAGE ligand, accumulates in AD brains and interacts with RAGE, contributing to Aβ_1–42 neurotoxicity. We questioned whether the binding of CAP37, neutrophil elastase and/or cathepsin G to RAGE could interfere with Aβ_1–42 binding to RAGE. Using ELISAs, we determined that CAP37 and neutrophil elastase inhibited binding of Aβ_1–42 to RAGE, and this effect was reversed by protease inhibitors in the case of neutrophil elastase. Since neutrophil elastase and cathepsin G have enzymatic activity, mass spectrometry was performed to determine the proteolytic activity of all three neutrophil proteins on Aβ_1–42. All three neutrophil proteins bound to Aβ_1–42 with different affinities and cleaved Aβ_1–42 with different kinetics and substrate specificities. We posit that these neutrophil proteins could modulate neurotoxicity in AD by cleaving Aβ_1–42 and influencing the Aβ1–42 –RAGE interaction. Further studies will be required to determine the biological significance of these effects and their relevance in neurodegenerative diseases such as AD. Our findings identify a novel area of study that underscores the importance of neutrophils and neutrophil proteins in neuroinflammatory diseases such as AD.

Synthetic ligands of the elastin receptor induce elastogenesis in human dermal fibroblasts via activation of their IGF-1 receptors

BACKGROUND

We have previously reported that a mixture of peptides obtained after chemical or enzymatic degradation of bovine elastin, induced new elastogenesis in human skin.

OBJECTIVE

Now, we investigated the elastogenic potential of synthetic peptides mimicking the elastin-derived, VGVAPG sequence, IGVAPG sequence that we found in the rice bran, and a similar peptide, VGVTAG that we identified in the IGF-1-binding protein-1 (IGFBP-1).

RESULTS

We now demonstrate that treatment with each of these xGVxxG peptides (recognizable by the anti-elastin antibody), up-regulated the levels of elastin-encoding mRNA, tropoelastin protein, and the deposition of new elastic fibers in cultures of human dermal fibroblasts and in cultured explants of human skin. Importantly, we found that such induction of new elastogenesis may involve two parallel signaling pathways triggered after activation of IGF-1 receptor. In the first one, the xGVxxG peptides interact with the cell surface elastin receptor, thereby causing the downstream activation of the c-Src kinase and a consequent cross-activation of the adjacent IGF-1R, even in the absence of its principal ligand. In the second pathway their hydrophobic association with the N-terminal domain (VGVTAG) of the serum-derived IGFBP-1 induces conformational changes of this IGF-1 chaperone allowing for the release of its cargo and a consequent ligand-specific phosphorylation of IGF-1R.

CONCLUSION

We present a novel, clinically relevant mechanism in which products of partial degradation of dermal elastin may stimulate production of new elastic fibers by dermal fibroblasts. Our findings particularly encourage the use of biologically safe synthetic xGVxxG peptides for regeneration of the injured or aged human skin.

Effects of IGFBP-1 and IGFBP-2 and their fragments on migration and IGF-induced proliferation of human dermal fibroblasts

OBJECTIVE

A family of six insulin-like growth factor (IGF) binding-proteins (IGFBP) bind to IGF-I and IGF-II with high affinity and modulate their activity. We have recently shown that a neutrophil-derived protease activity cleaved IGFBP-1, -2 and -4. IGFBP-1 and IGFBP-2 have a C-terminal Arg-Gly-Asp (RGD) sequence, and IGFBP-1 has been shown by others to stimulate migration through binding of its RGD sequence to α5β1 integrin. The aim of this study was to determine the effect of this IGFBP protease on IGF-induced proliferation and the effect of IGFBP-1 and IGFBP-2 and their proteolytic fragments on migration in normal and high glucose of human dermal fibroblasts (HDF).

DESIGN

We investigated the effect of intact or cleaved IGFBP-1 and -2 on proliferation in cultured HDFs and on HDF migration in normal and high glucose.

RESULTS

Both IGFBP-1 and IGFBP-2 and their proteolytic fragments stimulated HDF migration and the stimulatory effect was abolished by pre-treating cells with a α5β1 integrin antibody. High glucose impaired migration of HDFs; however, the addition of IGFBP-1, IGFBP-2 or fragments increased migration to levels observed in normoglycemia. IGFBP-2 inhibited IGF-II induced proliferation; however, the inhibitory effect was reduced after being cleaved. Intact native IGFBP-1 showed either potentiating or inhibitory effects on IGF-I induced proliferation depending on the confluence of cells, and proteolysis of IGFBP-1 did not change these effects. IGFBP-1 was found to increase phosphorylation of FAK and ERK1/2 and this effect was inhibited by the monoclonal integrin a5β1 ab.

CONCLUSIONS

IGFBP-1 and -2 and their proteolytic fragments may improve tissue repair under inflammatory conditions, through effects on proliferation and migration of HDFs in normal and high glucose.

IGFBP-2 - taking the lead in growth, metabolism and cancer

The activity of the Insulin-like Growth Factors (IGFs) ligands elicited via their receptors and transduced by various intracellular signal pathways is modulated by the IGF Binding Proteins (IGFBPs). Among all the IGFBPs, IGFBP-2 has been implicated in the regulation of IGF activity in most tissue and organs. Besides binding to IGFs in the circulation these IGF-regulatory activities of IGFBP-2 involve interactions with components of the extracellular matrix, cell surface proteoglycans and integrin receptors. In addition to these local peri-cellular activities, IGFBP-2 exerts other key functions within the nucleus, where IGFBP-2 directly or indirectly promotes transcriptional activation of specific genes. All of these IGFBP-2 activities, intrinsic or dependent on IGFs, contribute to its functional roles in growth/development, metabolism and malignancy as evidenced by studies in IGFBP-2 animal models and also by many in vitro studies. Finally, preclinical studies have demonstrated that IGFBP-2 administration can be beneficial in improving metabolic responses (inhibition of adipogenesis and enhanced insulin sensitivity), while blockade of IGFBP-2 appears to be an effective approach to inhibiting tumour growth and metastasis.

Neutrophil roles in left ventricular remodeling following myocardial infarction

Polymorphonuclear granulocytes (PMNs; neutrophils) serve as key effector cells in the innate immune system and provide the first line of defense against invading microorganisms. In addition to producing inflammatory cytokines and chemokines and undergoing a respiratory burst that stimulates the release of reactive oxygen species, PMNs also degranulate to release components that kill pathogens. Recently, neutrophil extracellular traps have been shown to be an alternative way to trap microorganisms and contain infection. PMN-derived granule components are also involved in multiple non-infectious inflammatory processes, including the response to myocardial infarction (MI). In this review, we will discuss the biological characteristics, recruitment, activation, and removal of PMNs, as well as the roles of PMN-derived granule proteins in inflammation and innate immunity, focusing on the MI setting when applicable. We also discuss future perspectives that will direct research in PMN biology.

α-Defensins in human innate immunity

Defensins are small, multifunctional cationic peptides. They typically contain six conserved cysteines whose three intramolecular disulfides stabilize a largely β-sheet structure. This review of human α-defensins begins by describing their evolution, including their likely relationship to the Big Defensins of invertebrates, and their kinship to the β-defensin peptides of many if not all vertebrates, and the θ-defensins found in certain non-human primates. We provide a short history of the search for leukocyte-derived microbicidal molecules, emphasizing the roles played by luck (good), preconceived notions (mostly bad), and proper timing (essential). The antimicrobial, antiviral, antitoxic, and binding properties of human α-defensins are summarized. The structural features of α-defensins are described extensively and their functional contributions are assessed. The properties of HD6, an enigmatic Paneth cell α-defensin, are contrasted with those of the four myeloid α-defensins (HNP1-4) and of HD5, the other α-defensin of human Paneth cells. The review ends with a decalogue that may assist researchers or students interested in α-defensins and related aspects of neutrophil function.