In vivo detection of secreted proteins from wounded skin using capillary ultrafiltration probes and mass spectrometric proteomics

Simultaneous quantification of TB-500 and its metabolites in in-vitro experiments and rats by UHPLC-Q-Exactive orbitrap MS/MS and their screening by wound healing activities in-vitro

BACKGROUND

TB-500 (Ac-LKKTETQ), derived from the active site of thymosin β4 (Tβ4), has various biological functions in its unacetylated form, LKKTETQ. These functions include actin binding, dermal wound healing, angiogenesis, and skin repair. The biological effects of TB-500, however, have not been documented. And the analysis of TB-500 and its metabolites have been neither simultaneously quantified nor structurally identified using synthesized authentic standards.

METHODS

This study was aimed to investigating simultaneous analytical methods of TB-500 and its metabolites in in-vitro and urine samples by using UHPLC-Q-Exactive orbitrap MS, and to comparing the biological activity of its metabolites with the parent TB-500. The metabolism of TB-500 was investigated in human serum, various in-vitro enzyme systems, and urine samples from rats treated with TB-500, and their biological activities measured by cytotoxicity and wound healing experiments were also evaluated in fibroblasts.

RESULTS

The simultaneous analytical method for TB-500 and its metabolites was developed and validated. The study found that Ac-LK was the primary metabolite with the highest concentration in rats at 0-6 h intervals. Also, the metabolite Ac-LKK was a long-term metabolite of TB-500 detected up to 72 hr. No cytotoxicity of the parent and its metabolites was found. Ac-LKKTE only showed a significant wound healing activity compared to the control.

CONCLUSION

The study provides a valuable tool for quantifying TB-500 and its metabolites, contributing to the understanding of metabolism and potential therapeutic applications. Our results also suggest that the previously reported wound-healing activity of TB-500 in literature may be due to its metabolite Ac-LKKTE rather than the parent form.

Detection and quantification of the metabolite Ac-Tβ1-14 in in vitro experiments and urine of rats treated with Ac-Tβ4: A potential biomarker of Ac-Tβ4 for doping tests

Thymosin β4 (Tβ4) was reported to exert various beneficial bioactivities such as tissue repair, anti-inflammation, and reduced scar formation, and it is listed on the prohibited substances in sports by the World Anti-Doping Agency. However, no metabolism studies of Tβ4 were reported yet. Previously, our lab reported in in vitro experiment that a total of 13 metabolites were found by using multiple enzymes, and six metabolites (Ac-Tβ31-43 , Ac-Tβ17-43 , Ac-Tβ1-11 , Ac-Tβ1-14 , Ac-Tβ1-15 , and Ac-Tβ1-17 ) were confirmed by comparing with the synthetic standards. This study was aimed at identifying new metabolites of Tβ4 leucine aminopeptidase (LAP), human kidney microsomes (HKM), cultured huvec cells, and rats after administration of Tβ4 protein to develop biomarkers for detecting doping drugs in sports. A method for detecting and quantifying Ac-Tβ1-14 was developed and validated using Q-Exactive orbitrap mass spectrometry. The limit of detection (LOD) and limit of quantification (LOQ) of the Ac-Tβ1-14 were 0.19 and 0.58 ng/mL, respectively, and showed a good linearity (r2  = 0.9998). As a result, among the six metabolites above, Ac-Tβ1-14 , as a common metabolite, was found in LAP, HKM, huvec cells exposed to Tβ4, and the urine of rats intraperitoneally treated with 20-mg/kg Tβ4. And the metabolite Ac-Tβ1-14 was quantitatively determined by 48 h in rats, with the highest concentration occurring between 0 and 6 h. Ac-Tβ1-14 was not detected in non-treated control groups, including human blank urine. These results suggest that Ac-Tβ1-14 in urine is a potential biomarker for screening the parent Tβ4 in doping tests.

nWASP Inhibition Increases Wound Healing via TrKb/PLCγ Signalling

(1) Background: Chronic wounds represent a major burden to patients and healthcare systems and identifying new therapeutic targets to encourage wound healing is a significant challenge. This study evaluated nWASP as a new therapeutic target in human wound healing and determined how this can be regulated. (2) Methods: Clinical cohorts from patients with chronic wounds were tested for the expression of nWASP and cell models were employed to evaluate the influence of nWASP on cellular functions that are key to the healing process following knockdown and/or the use of nWASP-specific inhibitors. (3) Results: nWASP was significantly elevated at transcript levels in human non-healing chronic wounds versus healing tissues. nWASP inhibitors, wiskostatin and 187-1, along with the knockdown of nWASP, modified both HaCaT and HECV cell behaviour. We then identified two signalling pathways affected by nWASP inhibition: TrkB signalling and downstream PLCγ1 phosphorylation were impaired by nWASP inhibition in HaCaT cells. The healing of wounds in a diabetic murine model was significantly improved with an nWASP inhibitor treatment. (4) Conclusions: This study showed that nWASP activity was related to the non-healing behaviour of chronic wounds and together with the findings in the in vivo models, it strongly suggested nWASP as a therapeutic target in non-healing wounds that are regulated via TrkB and PLCγ1 signalling.

Germinal peptide eye drops promote corneal wound healing and decrease inflammation after alkali injury

Germinal peptide is being developed to treat corneal injuries. The purpose of this study was to investigate its effect on corneal epithelial cells in vitro and its ability to promote healing in an alkali injury model in vivo. Cultured rabbit corneal epithelial cells were treated with germinal peptide at three concentrations. Cell proliferation and migration were assessed and compared with the effect of recombinant human epidermal growth factor (rh-EGF). In vivo, the corneas of New Zealand albino rabbits were chemically burned with 1 mol/l NaOH for 30 s. The injured eyes were topically treated with germinal peptide (10, 20, and 40 μg/ml), rh-EGF, or phosphate-buffered saline thrice daily. At fixed time points post injury, the healing of the cornea and its histopathology were evaluated. There was no difference in the effect of germinal peptide on cultured cell proliferation. However, cell migration was significantly higher than that in the control groups, with germinal peptide at concentrations of 20 and 40 μg/ml being the most efficacious. In vivo, 20 and 40 μg/ml germinal peptide significantly alleviated corneal opacity and edema. By day 21, the areas of corneal neovascularization in the germinal peptide-treated groups were smaller than those in the rh-EGF and control groups. The repaired corneas in the germinal peptide- and rh-EGF-treated groups also had more corneal epithelial layers and fewer inflammatory cells than the controls. Germinal peptide may be developed as a novel topical treatment agent for corneal wound healing in clinical settings.

Thymosin beta 10 is a key regulator of tumorigenesis and metastasis and a novel serum marker in breast cancer

Background

Thymosin beta 10 (TMSB10) has been demonstrated to be involved in the malignant process of many cancers. The purpose of this study was to determine the biological roles and clinical significance of TMSB10 in breast cancer and to identify whether TMSB10 might be used as a serum marker for the diagnosis of breast cancer.

Methods

TMSB10 expression was evaluated by immunohistochemical analysis (IHC) of 253 breast tumors and ELISA of serum from 80 patients with breast cancer. Statistical analysis was performed to explore the correlation between TMSB10 expression and clinicopathological features in breast cancer. Univariate and multivariate Cox regression analysis were performed to examine the association between TMSB10 expression and overall survival and metastatic status. In vitro and in vivo assays were performed to assess the biological roles of TMSB10 in breast cancer. Western blotting and luciferase assays were examined to identify the underlying pathway involved in the tumor-promoting role of TMSB10.

Results

We found TMSB10 was upregulated in breast cancer cells and tissues. Univariate and multivariate analysis demonstrated that high TMSB10 expression significantly correlated with clinicopathological features, poor prognosis and distant metastases in patients with breast cancer. Overexpression of TMSB10 promotes, while silencing of TMSB10 inhibits, proliferation, invasion and migration of breast cancer cells in vitro and in vivo. Our results further reveal that TMSB10 promotes the proliferation, invasion and migration of breast cancer cells via AKT/FOXO signaling, which is antagonized by the AKT kinase inhibitor perifosine. Importantly, the expression of TMSB10 is significantly elevated in the serum of patients with breast cancer and is positively associated with clinical stages of breast cancer.

Conclusion

TMSB10 may hold promise as a minimally invasive serum cancer biomarker for the diagnosis of breast cancer and a potential therapeutic target which will facilitate the development of a novel therapeutic strategy against breast cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-016-0785-2) contains supplementary material, which is available to authorized users.

Thymosin β4 Promotes Dermal Healing

No agent has been identified that significantly accelerates the repair of chronic dermal wounds in humans. Thymosin beta 4 (Tβ4) is a small, abundant, naturally occurring regenerative protein that is found in body fluids and inside cells. It was found to have angiogenic and antiinflammatory activity and to be high in platelets that aggregate at the wound site. Thus we used Tβ4 initially in dermal healing. It has since been shown to have many activities important in tissue protection, repair, and regeneration. Tβ4 increases the rate of dermal healing in various preclinical animal models, including diabetic and aged animals, and is active for burns as well. Tβ4 also accelerated the rate of repair in phase 2 trials with patients having pressure ulcers, stasis ulcers, and epidermolysis bullosa wounds. It is safe and well tolerated and will likely have additional uses in the skin and in injured organs for tissue repair and regeneration.

Interstitial fluid-a reflection of the tumor cell microenvironment and secretome

The interstitium or interstitial space describes the space outside the blood and lymphatic vessels. It contains two phases; the interstitial fluid (IF) and the extracellular matrix. In this review we focus on the interstitial fluid phase, which is the physical and biochemical microenvironment of the cells, and more specifically that of tumors. IF is created by transcapillary filtration and cleared by lymphatic vessels, and contains substances that are either produced and secreted locally, thus denoted secretome, or brought to the organ by the circulation. The structure of the interstitium is discussed briefly and moreover techniques for IF isolation focusing on those that are relevant for studies of the secretome. Accumulated data show that tumor IF is hypoxic and acidic compared with subcutaneous IF and plasma, and that there are gradients between IF and plasma giving information on where substances are produced and thereby reflecting the local microenvironment. We review recent data on the origin of tissue specific substances, challenges related to isolating a representative secretome and the use of this as a substrate for biomarker identification. Finally we perform a comparative analysis across human tumor types and techniques and show that there is great variation in the results obtained that may at least partially be due to the isolation method used. We conclude that when care is taken in isolation of substrate, analysis of the secretome may give valuable biological insight and result in identification of biomarker candidates. This article is part of a Special Issue entitled: An Updated Secretome.

Thymosin β4 is rapidly internalized by cells and does not induce intracellular Ca2+ elevation

Thymosin β4 (Tβ4) is a multifunctional protein that has pleiotropic activities both intracellularly and extracellularly. The mechanisms by which it influences cellular processes such as adhesion, migration, differentiation, or apoptosis are not yet understood. Calcium is a ubiquitous signal molecule that is involved in the regulation of almost all cellular functions. Our data indicate that the release of Ca(2+) from intracellular stores following stimulation of cells with Tβ4 does not occur. Interestingly, Tβ4 becomes rapidly internalized, supporting the concept that it may express its activities via intracellular receptors.

Sampling human indigenous saliva peptidome using a lollipop-like ultrafiltration probe: simplify and enhance peptide detection for clinical mass spectrometry

Although human saliva proteome and peptidome have been revealed they were majorly identified from tryptic digests of saliva proteins. Identification of indigenous peptidome of human saliva without prior digestion with exogenous enzymes becomes imperative, since native peptides in human saliva provide potential values for diagnosing disease, predicting disease progression, and monitoring therapeutic efficacy. Appropriate sampling is a critical step for enhancement of identification of human indigenous saliva peptidome. Traditional methods of sampling human saliva involving centrifugation to remove debris may be too time-consuming to be applicable for clinical use. Furthermore, debris removal by centrifugation may be unable to clean most of the infected pathogens and remove the high abundance proteins that often hinder the identification of low abundance peptidome. Conventional proteomic approaches that primarily utilize two-dimensional gel electrophoresis (2-DE) gels in conjugation with in-gel digestion are capable of identifying many saliva proteins. However, this approach is generally not sufficiently sensitive to detect low abundance peptides/proteins. Liquid chromatography-Mass spectrometry (LC-MS) based proteomics is an alternative that can identify proteins without prior 2-DE separation. Although this approach provides higher sensitivity, it generally needs prior sample pre-fractionation and pre-digestion with trypsin, which makes it difficult for clinical use. To circumvent the hindrance in mass spectrometry due to sample preparation, we have developed a technique called capillary ultrafiltration (CUF) probes. Data from our laboratory demonstrated that the CUF probes are capable of capturing proteins in vivo from various microenvironments in animals in a dynamic and minimally invasive manner. No centrifugation is needed since a negative pressure is created by simply syringe withdrawing during sample collection. The CUF probes combined with LC-MS have successfully identified tryptic-digested proteins. In this study, we upgraded the ultrafiltration sampling technique by creating a lollipop-like ultrafiltration (LLUF) probe that can easily fit in the human oral cavity. The direct analysis by LC-MS without trypsin digestion showed that human saliva indigenously contains many peptide fragments derived from various proteins. Sampling saliva with LLUF probes avoided centrifugation but effectively removed many larger and high abundance proteins. Our mass spectrometric results illustrated that many low abundance peptides became detectable after filtering out larger proteins with LLUF probes. Detection of low abundance saliva peptides was independent of multiple-step sample separation with chromatography. For clinical application, the LLUF probes incorporated with LC-MS could potentially be used in the future to monitor disease progression from saliva.

Interstitial Fluid and Lymph Formation and Transport: Physiological Regulation and Roles in Inflammation and Cancer

The interstitium describes the fluid, proteins, solutes, and the extracellular matrix (ECM) that comprise the cellular microenvironment in tissues. Its alterations are fundamental to changes in cell function in inflammation, pathogenesis, and cancer. Interstitial fluid (IF) is created by transcapillary filtration and cleared by lymphatic vessels. Herein we discuss the biophysical, biomechanical, and functional implications of IF in normal and pathological tissue states from both fluid balance and cell function perspectives. We also discuss analysis methods to access IF, which enables quantification of the cellular microenvironment; such methods have demonstrated, for example, that there can be dramatic gradients from tissue to plasma during inflammation and that tumor IF is hypoxic and acidic compared with subcutaneous IF and plasma. Accumulated recent data show that IF and its convection through the interstitium and delivery to the lymph nodes have many and diverse biological effects, including in ECM reorganization, cell migration, and capillary morphogenesis as well as in immunity and peripheral tolerance. This review integrates the biophysical, biomechanical, and biological aspects of interstitial and lymph fluid and its transport in tissue physiology, pathophysiology, and immune regulation.

Comparative proteomic analysis of secreted proteins from nasopharyngeal carcinoma-associated stromal fibroblasts and normal fibroblasts

Since the concept of the secretome (ensemble of proteins secreted and/or shed from cells) was proposed, it has become an attractive and challenging proteomic technology in recent years. However, secretome analysis still faces some difficulties mainly related to sample collection and preparation. In the present study, we established a reliable method for extracting secreted proteins by ultrafiltration centrifugation and conducting secretomic analysis. Accumulating evidence suggests that carcinoma-associated stromal fibroblasts (CAFs) play an important role in cancer initiation and progression. To investigate the expression patterns of secreted proteins from fibroblasts and to identify the secreted proteins involved in nasopharyngeal carcinoma (NPC) carcinogenesis, we conducted comparative secretome analysis between CAFs and normal fibroblasts. After two-dimensional gel electrophoresis (2-D PAGE), 11 significant spots were differentially expressed and identified by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). These proteins may take part in the regulation of the tumor micro-environment through different processes. The expression level of galectin-1 in the CAF supernatant was also determined by ELISA. This study provides useful information and new clues for the further understanding of the regulatory mechanisms of CAFs in the NPC microenvironment.

Comprehensive transcriptome and immunophenotype analysis of renal and cardiac MSC-like populations supports strong congruence with bone marrow MSC despite maintenance of distinct identities

Cells resembling bone marrow mesenchymal stem cells (MSC) have been isolated from many organs but their functional relationships have not been thoroughly examined. Here we compared the immunophenotype, gene expression, multipotency and immunosuppressive potential of MSC-like colony-forming cells from adult murine bone marrow (bmMSC), kidney (kCFU-F) and heart (cCFU-F), cultured under uniform conditions. All populations showed classic MSC morphology and in vitro mesodermal multipotency. Of the two solid organ-specific CFU-F, only kCFU-F displayed suppression of T-cell alloreactivity in vitro, albeit to a lesser extent than bmMSC. Quantitative immunophenotyping using 81 phycoerythrin-conjugated CD antibodies demonstrated that all populations contained high percentages of cells expressing diagnostic MSC surface markers (Sca1, CD90.2, CD29, CD44), as well as others noted previously on murine MSC (CD24, CD49e, CD51, CD80, CD81, CD105). Illumina microarray expression profiling and bioinformatic analysis indicated a correlation of gene expression of 0.88-0.92 between pairwise comparisons. All populations expressed approximately 66% of genes in the pluripotency network (Plurinet), presumably reflecting their stem-like character. Furthermore, all populations expressed genes involved in immunomodulation, homing and tissue repair, suggesting these as conserved functions for MSC-like cells in solid organs. Despite this molecular congruence, strong biases in gene and protein expression and pathway activity were seen, suggesting organ-specific functions. Hence, tissue-derived MSC may also retain unique properties potentially rendering them more appropriate as cellular therapeutic agents for their organ of origin.

Spatial mapping by imaging mass spectrometry offers advancements for rapid definition of human skin proteomic signatures

Investigations into the human skin proteome by classical analytical procedures have not addressed spatial molecular distributions in whole-skin biopsies. The aim of this study was to develop methods for the detection of protein signatures and their spatial disposition in human skin using advanced molecular imaging technology based on mass spectrometry technologies. This technology allows for the generation of protein images at specific molecular weight values without the use of antibody while maintaining tissue architecture. Two experimental approaches were employed: MALDI-MS profiling, where mass spectra were taken from discrete locations based on histology, and MALDI-IMS imaging, where complete molecular images were obtained at various MW values. In addition, proteins were identified by in situ tryptic digestion, sequence analysis of the fragment peptides and protein database searching. We have detected patterns of protein differences that exist between epidermis and dermis as well as subtle regional differences between the papillary and reticular dermis. Furthermore, we were able to detect proteins that are constitutive features of human skin as well as those associated with unique markers of individual variability.

Regenerative protein thymosin beta-4 is a novel regulator of purinergic signaling

By an unknown mechanism, β-thymosins are extracellular modulators of angiogenesis, inflammation, wound healing, and development. We were interested in identifying β-thymosin interactors and determining their importance in β-thymosins signaling in human vein endothelial cells (HUVECs). We performed pulldown experiments with biotinylated thymosin β-4 (Tβ4) in comparison to neutravidin beads alone and used mass spectrometric analysis to identify differentially interacting proteins. By this method, we identified F1-F0 ATP synthase, a known target of antiangiogenic angiostatin. By surface plasmon resonance, we determined for Tβ4 binding to the β subunit of ATP synthase a K(D) of 12 nM. Blocking antibodies and antagonists (oligomycin, IC(50) ∼1.8 μM; piceatannol, IC(50) ∼1.05 μM; and angiostatin, IC(50) ∼2.9 μg/ml) of ATP synthase inhibited the Tβ4-induced increase in cell surface ATP levels, as measured by luciferase assay, and the Tβ4-induced increase in HUVEC migration, as measured by transwell migration assay. Silencing of the ATP-responsive purinergic receptor P2X4 with siRNA also blocked Tβ4-induced HUVEC migration in a transwell assay. Furthermore, in silico we identified common amphiphilic α-helical structural similarities between β-thymosins and the inhibitory factor 1 (IF1), an inhibitor of ATP synthase hydrolysis. In summary, we have identified an extracellular signaling pathway where Tβ4 increases cell surface ATP levels via ATP synthase and have shown further that ATP-responsive P2X4 receptor is required for Tβ4-induced HUVEC migration.

Thymosin beta4 inhibits TNF-alpha-induced NF-kappaB activation, IL-8 expression, and the sensitizing effects by its partners PINCH-1 and ILK

The mechanisms by which thymosin β 4 (Tβ(4)) regulates the inflammatory response to injury are poorly understood. Previously, we demonstrated that ectopic Tβ(4) treatment inhibits injury-induced proinflammatory cytokine and chemokine production. We have also shown that Tβ(4) suppresses TNF-α-mediated NF-κB activation. Herein, we present novel evidence that Tβ(4) directly targets the NF-κB RelA/p65 subunit. We find that enforced expression of Tβ(4) interferes with TNF-α-mediated NF-κB activation, as well as downstream IL-8 gene transcription. These activities are independent of the G-actin-binding properties of Tβ(4). Tβ(4) blocks RelA/p65 nuclear translocation and targeting to the cognate κB site in the proximal region of the IL-8 gene promoter. Tβ(4) also inhibits the sensitizing effects of its intracellular binding partners, PINCH-1 and ILK, on NF-κB activity after TNF-α stimulation. The identification of a functional regulatory role by Tβ(4) and the focal adhesion proteins PINCH-1 and ILK on NF-κB activity in this study opens a new window for scientific exploration of how Tβ(4) modulates inflammation. In addition, the results of this study serve as a foundation for developing Tβ(4) as a new anti-inflammatory therapy.

Thymosins and muscle regeneration

Thymosins are a family of highly conserved small peptides originally isolated from calf thymus. One representative member of the family is thymosin-β₄ (Tβ₄), a major G-actin-sequestering peptide present in many tissues. In the last decade, various studies have uncovered several important functions for Tβ₄ related to the regeneration of injured tissues including skin and heart. In particular, Tβ₄ promotes endothelial cell migration via the activation of Akt2 kinase at the leading edge of the cell. In the case of skeletal muscle injury, increased levels of Tβ₄ are produced by muscle fibers and surrounding immune cells. Satellite cell-derived myoblasts and myocytes are chemoattracted by Tβ₄, which facilitates skeletal muscle regeneration. Recently, it was reported that Tβ₄ interacts physically with F₁-F₀ ATP synthase on the plasma membrane to increase the local concentration of ATP, which stimulates the P2X₄ purinergic receptor to elicit a migratory response from endothelial cells. Thus, it is clear that Tβ₄ is an important chemotactic factor involved in stem/progenitor cell-mediated tissue regeneration.

Interstitial fluid: the overlooked component of the tumor microenvironment?

Background

The interstitium, situated between the blood and lymph vessels and the cells, consists of a solid or matrix phase and a fluid phase, together constituting the tissue microenvironment. Here we focus on the interstitial fluid phase of tumors, i.e., the fluid bathing the tumor and stromal cells. Novel knowledge on this compartment may provide important insight into how tumors develop and how they respond to therapy.

Results

We discuss available techniques for interstitial fluid isolation and implications of recent findings with respect to transcapillary fluid balance and uptake of macromolecular therapeutic agents. By the development of new methods it is emerging that local gradients exist in signaling substances from neoplastic tissue to plasma. Such gradients may provide new insight into the biology of tumors and mechanistic aspects linked to therapy. The emergence of sensitive proteomic technologies has made the interstitial fluid compartment in general and that of tumors in particular a highly valuable source for tissue-specific proteins that may serve as biomarker candidates. Potential biomarkers will appear locally at high concentrations in the tissue of interest and will eventually appear in the plasma, where they are diluted.

Conclusions

Access to fluid that reliably reflects the local microenvironment enables us to identify substances that can be used in early detection and monitoring of disease.

Hemopressin and other bioactive peptides from cytosolic proteins: are these non-classical neuropeptides?

Peptides perform many roles in cell-cell signaling; examples include neuropeptides, hormones, and growth factors. Although the vast majority of known neuropeptides are produced in the secretory pathway, a number of bioactive peptides are derived from cytosolic proteins. For example, the hemopressins are a family of peptides derived from alpha and beta hemoglobin which bind to the CB1 cannabinoid receptor, functioning as agonists or antagonists/inverse agonists depending on the size of the peptide. However, the finding that peptides derived from cytosolic proteins can affect receptors does not prove that these peptides are true endogenous signaling molecules. In order for the hemopressins and other peptides derived from cytosolic proteins to be considered neuropeptide-like signaling molecules, they must be synthesized in brain, they must be secreted in levels sufficient to produce effects, and either their synthesis or secretion should be regulated. If these criteria are met, we propose the name "non-classical neuropeptide" for this category of cytosolic bioactive peptide. This would be analogous to the non-classical neurotransmitters, such as nitric oxide and anandamide, which are not stored in secretory vesicles and released upon stimulation but are synthesized upon stimulation and constitutively released. We review some examples of cytosolic peptides from various protein precursors, describe potential mechanisms of their biosynthesis and secretion, and discuss the possibility that these peptides are signaling molecules in the brain, focusing on the criteria that these peptides would have to fill in order to be considered non-classical neuropeptides.

Bioengineering a humanized acne microenvironment model: proteomics analysis of host responses to Propionibacterium acnes infection in vivo

Acne is a human disease of the sebaceous hair follicle. Unlike humans, most animals produce little or no triglycerides in hair follicles to harbor Propionibacterium acnes a fact that has encumbered the development of novel treatments for acne lesions. Although genetic mutant mice with acne-like skins have been used for screening anti-acne drugs, the mice generally have deficits in immune system that turns out to be inappropriate to generate antibodies for developing acne vaccines. Here, we employed a bioengineering approach using a tissue chamber integrated with a dermis-based cell-trapped system (DBCTS) to mimic the in vivo microenvironment of acne lesions. Human sebocyte cell lines were grown in DBCTS as a scaffold and inserted into a perforated tissue chamber. After implantation of a tissue chamber bearing human sebocytes into ICR mice, P. acnes or PBS was injected into a tissue chamber to induce host immune response. Infiltrated cells such as neutrophils and macrophages were detectable in tissue chamber fluids. In addition, a proinflammatory cytokine macrophage-inflammatory protein-2 (MIP-2) was elevated after P. acnes injection. In tissue chamber fluids, 13 proteins including secreted proteins and cell matrix derived from mouse, human cells or P. acnes were identified by proteomics using isotope-coded protein label (ICPL) coupled to nano-LC-MS analysis. After P. acnes infection, four proteins including fibrinogen, alpha polypeptide, fibrinogen beta chain, S100A9, and serine protease inhibitor A3K showed altered concentrations in the mimicked acne microenvironment. The bioengineered acne model thus provides an in vivo microenvironment to study the interaction of host with P. acnes and offers a unique set-up for screening novel anti-acne drugs and vaccines.

Increased plasma concentrations of cytoskeletal and Ca2+-binding proteins and their peptides in psoriasis patients

BACKGROUND

The mechanisms underlying psoriatic pathogenesis are not fully understood and might be elucidated by identifying novel disease-related molecular markers, including autoantigens.

METHODS

We used 2 proteomic methods to analyze plasma samples from 20 psoriasis patients and 20 matched healthy donors. The first method focused on evaluating changes in glycoprotein concentrations and the plasma proteome, and the second method assessed endogenous proteolytic activity by analyzing the low molecular weight component of plasma.

RESULTS

The integrated proteomic and peptidomic analysis identified a number of proteins and their fragments present at different concentrations in the plasma of psoriasis patients and healthy donors. We used ELISA to independently verify the changes in the concentrations of several of these proteins. One intriguing finding, increased concentrations of cytoskeletal and actin-binding proteins and their peptides in psoriatic plasma, suggested disease-related cell leakage of these proteins and their increased proteolysis. Among the increased proteins and peptides were thymosin beta 4, talin 1, actin gamma, filamin, and profilin. Increased concentrations of Ca(2+)-binding proteins calgranulins A and B in psoriatic plasma were also observed, confirming previous reports, and appeared to be relevant to the increase of cytoskeletal components. Another notable change in psoriatic plasma was a striking decrease in fibrinogen fragments.

CONCLUSIONS

The identified increased concentrations of cytoskeletal proteins, their peptides, and calgranulins in psoriatic plasma, as well as the underlying altered protease activity, are proposed to be related to psoriasis pathogenesis.

In vivo tumor secretion probing via ultrafiltration and tissue chamber: implication for anti-cancer drugs targeting secretome

Tumor secreted proteins/peptides (tumor secretome) act as mediators of tumor-host communication in the tumor microenvironment. Therefore, development of anti-cancer drugs targeting secretome may effectively control tumor progression. Novel techniques including a capillary ultrafiltration (CUF) probe and a dermis-based cell-trapped system (DBCTS) linked to a tissue chamber were utilized to sample in vivo secretome from tumor masses and microenvironments. The CUF probe and tissue chamber were evaluated in the context of in vivo secretome sampling. Both techniques have been successfully integrated with mass spectrometry for secretome identification. A secretome containing multiple proteins and peptides can be analyzed by NanoLC-LTQ mass spectrometry, which is specially suited to identifying proteins in a complex mixture. In the future, the establishment of comprehensive proteomes of various host and tumor cells, as well as plasma will help in distinguishing the cellular sources of secretome. Many detection methods have been patented regarding probes and peptide used for identification of tumors.

Active caspase-1 is a regulator of unconventional protein secretion

Mammalian cells export most proteins by the endoplasmic reticulum/Golgi-dependent pathway. However, some proteins are secreted via unconventional, poorly understood mechanisms. The latter include the proinflammatory cytokines interleukin(IL)-1beta, IL-18, and IL-33, which require activation by caspase-1 for biological activity. Caspase-1 itself is activated by innate immune complexes, the inflammasomes. Here we show that secretion of the leaderless proteins proIL-1alpha, caspase-1, and fibroblast growth factor (FGF)-2 depends on caspase-1 activity. Although proIL-1alpha and FGF-2 are not substrates of the protease, we demonstrated their physical interaction. Secretome analysis using iTRAQ proteomics revealed caspase-1-mediated secretion of other leaderless proteins with known or unknown extracellular functions. Strikingly, many of these proteins are involved in inflammation, cytoprotection, or tissue repair. These results provide evidence for an important role of caspase-1 in unconventional protein secretion. By this mechanism, stress-induced activation of caspase-1 directly links inflammation to cytoprotection, cell survival, and regenerative processes.

Quantitative proteomes and in vivo secretomes of progressive and regressive UV-induced fibrosarcoma tumor cells: mimicking tumor microenvironment using a dermis-based cell-trapped system linked to tissue chamber

The alterations of tumor proteome and/or in vivo secretome created by host-tumor cell interaction may be crucial factors for tumors to undergo progression or regression in a host system. Two UV-induced fibrosarcoma tumor cell lines (UV-2237 progressive cells and UV-2240 regressive cells) were used as models to address this issue. Hundreds of proteins including in vivo secretome have been identified and quantified via an isotope-coded protein label (ICPL) in conjunction with high-throughput NanoLC-LTQ MS analysis. A newly designed technology using a dermis-based cell-trapped system was employed to encapsulate and grow 3-D tumor cells. A tissue chamber inserted with a tumor cell-trapped dermis was implanted into mice to mimic the tumor microenvironment. The in vivo secretome created by host-tumor interaction was characterized from samples collected from tissue chamber fluids via ICPL labeling mass spectrometric analysis. Twenty-five proteins including 14-3-3 proteins, heat shock proteins, profilin-1, and a fragment of complement C3 with differential expression in proteomes of UV-2237 and UV-2240 cells were revealed. Three secreted proteins including myeloperoxidase, alpha-2-macroglobulin, and a vitamin D-binding protein have different abundances in the in vivo secretome in response to UV-2237 and UV-2240 cells. Differential tumor proteomes and in vivo secretome were thus accentuated as potential therapeutic targets to control tumor growth.

Breast tumor microenvironment: proteomics highlights the treatments targeting secretome

Tumor secreted substances (secretome), including extracellular matrix (ECM) components, act as mediators of tumor-host communication in the breast tumor microenvironment. Proteomic analysis has emphasized the value of the secretome as a source of prospective markers and drug targets for the treatment of breast cancers. Utilizing bioinformatics, our recent studies revealed global changes in protein expression after the activation of ECM-mediated signaling in breast cancer cells. A newly designed technique integrating a capillary ultrafiltration (CUF) probe with mass spectrometry was demonstrated to dynamically sample and identify in vivo and pure secretome from the tumor microenvironment. Such in vivo profiling of breast cancer secretomes may facilitate the development of novel drugs specifically targeting secretome.

Identification and characterization of thymosin beta-4 in chicken macrophages using whole cell MALDI-TOF

The aim of the study was to determine chicken monocyte- and granulocyte-associated peptides and proteins using "whole cell" matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) and to characterize the peptides based on their abundance. The mass spectra showed a prominent peak at m/z 4963 in monocytes/macrophages but not in the granulocytes. Subsequent purification and characterization of the m/z 4963 peptide from an avian macrophage cell line HTC, revealed it to be thymosin beta-4 (Tbeta-4), an actin-modulating peptide. HTC cells when treated with bacterial lipopolysaccharide and peptidoglycan to determine the modulation of Tbeta-4 gene expression or its secretion, showed no changes.

Recent advances in protein profiling of tissues and tissue fluids

Creating protein profiles of tissues and tissue fluids, which contain secreted proteins and peptides released from various cells, is critical for biomarker discovery as well as drug and vaccine target selection. It is extremely difficult to obtain pure samples from tissues or tissue fluids, however, and identification of complex protein mixtures is still a challenge for mass spectrometry analysis. Here, we summarize recent advances in techniques for extracting proteins from tissues for mass spectrometry profiling and imaging. We also introduce a novel technique using a capillary ultrafiltration (CUF) probe to enable in vivo collection of proteins from the tissue microenvironment. The CUF probe technique is compared with existing sampling techniques, including perfusion, saline wash, fine-needle aspiration and microdialysis. In this review, we also highlight quantitative mass spectrometric proteomic approaches with, and without, stable-isotope labels. Advances in quantitative proteomics will significantly improve protein profiling of tissue and tissue fluid samples collected by CUF probes.

Neuroprotective function of thymosin-beta and its derivative peptides on the programmed cell death of chick and rat neurons

Thymosin-betas (Tbetas) are small polypeptides with various biological functions, including cytoskeletal remodeling, angiogenesis, cellular migration, wound healing, and regulation of apoptosis. Recently, we found that Tbeta is involved in the control of programmed cell death (PCD) of motoneurons (MNs) in chick embryo, and that the anti-apoptotic action of Tbeta is independent of its actin-sequestering activity. In this study, we observed that a synthetic peptide derived from Tbeta suppressed staurosporine-induced neuronal apoptosis in vitro, and PCD of chick or rat MNs in vivo. Furthermore, inhibition of Tbeta4 in chick embryo by antibody significantly augmented the PCD of MNs, suggesting that secreted form of Tbeta is physiological regulator of PCD. Based on these findings, we propose that extracellularly secreted Tbeta is involved in the control of PCD of neurons during development, and Tbeta-derived peptides could be useful for the anti-apoptotic therapy of neuropathologies related to neuronal apoptosis.

In vivo secretome sampling technology for proteomics

Secretome is a critical mediator for cell-cell and microbe-cell interaction. Identification of secretome will endow researchers with important biomarkers and therapeutic targets as well as reinforce the current methods used in the systems biology research of cell-cell interactions. Here, we introduce an in vivo sampling technique using capillary ultrafiltration (CUF) probes that are capable of continuously collecting pure in vivo secretome from tissue microenvironments. Great benefits of CUF probes when compared with other current sampling techniques have been acknowledged. CUF probes can be designed to fit various in vivo models and they are easily adapted to different protein-detection systems including mass spectrometers. The future challenges and clinical advantages of CUF probe sampling are also highlighted in this review. Many prospective properties such as simple manipulation, dynamic sampling, pathogen clearance, online mass spectrometric coupling, and disease treatment and monitoring have made CUF probes attractive for clinical uses in the near future.

In vivo sampling of extracellular beta-thymosin by ultrafiltration probes

In vivo detection and monitoring of extracellular beta-thymosin will facilitate the understanding of their biological function and association with disease progression. A novel technique using capillary ultrafiltration (CUF) probes linked to mass spectrometry is capable of sensing extracellular thymosin beta-4 and/or thymosin beta-10 in vivo in wounded skin and other tissue microenvironments. In this review, we highlight the association of extracellular beta-thymosin with skin wound healing and the potential adjuvant effects on vaccination. The fabrication and biological application of CUF probes are also described. Data from CUF probe-captured beta-thymosin may guide future exploration of extracellular beta-thymosin.

Neurotrophic roles of the beta-thymosins in the development and regeneration of the nervous system

Beta-thymosins (Tbetas) are polypeptides abundant in the cytosol, nucleus, and extracellular space of many cell types. In the nervous system, the expression of Tbetas is regulated during the development of the central nervous system and following neuronal insults in cell-type and brain-region dependent manners, which may be related to the function of Tbetas in the growth and regeneration of the nervous system. Supporting such a proposition, overexpression of Tbetas in neurons has been shown to modify the axonal branches in vivo and neurite branches in vitro. These neurite-modifying functions have been suggested to be due to the activity of Tbetas to bind actin. In addition, we recently observed that Tbetas suppressed the apoptotic neuronal death in chick embryos, and these functions might be mediated by the extracellularly secreted form(s) of Tbetas. These results suggest that Tbetas play neurotrophic roles in the neuroprotection and neuronal growth/regeneration via their cytosolic actin-remodeling activity and extracellular antiapoptotic activity. Even though further verification is required, we also observed that Tbeta15 was translocated into the injured neuronal nuclei, and this event appeared to be an eliminatory process of the injured cells. Therefore, treatment with Tbetas or their related peptides appear to be beneficial for neuronal diseases by preventing neuronal death or promoting neuronal regeneration.