scholarly journals Ο ρόλος των μεμβρανικών γλυκοπρωτεϊνών στον καρκίνο των ωοθηκών

2013 ◽  
Author(s):  
Ντενάρντα Ντάνγκαη
Keyword(s):  
Suppressor Cells ◽  
Recombinant Antibodies ◽  
Myeloid Derived Suppressor Cells ◽  
In Trans ◽  
In Cis

Καθώς η θεραπεία του καρκίνου των ωοθηκών με τις συμβατικές χημειοθεραπείες δεν είναι αποτελεσματική, αναζητούνται προσεγγίσεις που στοχεύουν συγκεκριμένους καρκινικούς στόχους ή ειδικά σηματοδοτικά μονοπάτια.Ένας από τους στόχους αυτής της μελέτης ήταν η διερεύνηση του ρόλου των γλυκοπρωτεϊνών μεσοθηλίνη και CA125 στην εξέλιξη και μετάσταση του καρκίνου των ωοθηκών αλλά και η διερεύνηση εφαρμογών, που βασίζονται σε αντισώματα, με σκοπό τον περιορισμό των περιτοναϊκών μεταστάσεων. Έτσι, υποθέσαμε ότι η ταυτόχρονη στόχευση των δύο αυτών γλυκοπρωτεϊνών θα μπορούσε να περιορίσει πιο αποτελεσματικά τη μετάσταση. Για να ελέγξουμε την παραπάνω υπόθεση αναπτύξαμε ένα μοντέλο μεταστατικού καρκίνου των ωοθηκών στον ποντικό. Σύμφωνα με την in vivo απεικόνιση, η τοπική χορήγηση του συνδυασμού των δύο αντισωμάτων που στοχεύουν την μεσοθηλίνη και το CA125 περιόρισε τις μικρομεταστάσεις σε σύγκριση με τις ομάδες ποντικών στα οποία χορηγήθηκαν μεμονωμένα αντισώματα. Η ανάλυση των ανοσοποιητικών κυττάρων του καρκινικού μικροπεριβάλλοντος της περιτοναϊκής κοιλότητας έδειξε πως η συνδυασμένη θεραπεία περιόρισε α) τις μικρομεταστάσεις, β) το καρκινικό φορτίο και γ) τα δραστικά προερχόμενα από το μυελό ανοσοκατασταλτικά κύτταρα (myeloid-derived suppressor cells, MDSCs). Η σημασία της παρατήρησής μας είναι προφανής, αφού ένα καρκινικό μικροπεριβάλλον με λιγότερα ανοσοκατασταλτικά στοιχεία ευνοεί την ανοσολογική απόρριψη του όγκου.Η μεσοθηλίνη, εκτός από μια γλυκοπρωτεΐνη προσδεδεμένη στην κυτταρική επιφάνεια μέσω «άγκυρας» γλυκοσυλο-φωσφατιδυλο-ϊνοσιτόλης (GPI), υπάρχει και σε εκκρινόμενη μορφή και συνιστά έναν καρκινικό δείκτη στον ορό των ασθενών με καρκίνο των ωοθηκών. Διατυπώσαμε την υπόθεση ότι τα καρκινικά αντιγόνα με άγκυρα GPI όπως η μεσοθηλίνη, μπορούν να δεσμεύονται στον υποδοχέα της μαννόζης (MR) που εκφράζεται από τα μακροφάγα τα οποία διηθούν τους καρκίνους, μέσω των τελικών καταλοίπων μαννόζης. Επίσης η πρόσδεση της εκκρινόμενης από καρκινικά κύτταρα μεσοθηλίνης στον MR, θα μπορούσε να συνεισφέρει στην ενεργοποίηση των μακροφάγων προς έναν εναλλακτικό, σχετιζόμενο με τον καρκίνο φαινότυπο (TAM). Για να διερευνήσουμε την παραπάνω υπόθεση ελέγξαμε την ύπαρξη προσδεδεμένης μεσοθηλίνης στην επιφάνεια μακροφάγων από ασκίτες ασθενών με καρκίνο των ωοθηκών. Με κυτταρομετρία ροής βρήκαμε ότι τα μακροφάγα τα οποία εξέφραζαν τον υποδοχέα της μαννόζης είχαν στην επιφάνειά τους προσδεδεμένη μεσοθηλίνη. Σε in vitro πειράματα που περιελάμβαναν καλλιέργεια ώριμων μακροφάγων και καρκινικών σειρών ωοθήκης σε συστήματα transwell, επιβεβαιώσαμε την πρόσδεση της εκκρινόμενης από καρκινικά κύτταρα μεσοθηλίνης σε μακροφάγα που στο τεχνητό καρκινικό περιβάλλον υπερεκφράζουν τον υποδοχέα της μαννόζης. Επιπλέον, παρατηρήσαμε πως η εκκρινόμενη μεσοθηλίνη που δεν διαθέτει άγκυρα GPI δεν προσδένεται σε μακροφάγα. Για να αποδείξουμε πως η πρόσδεση οφειλόταν στον υποδοχέα της μαννόζης απομονώσαμε ανασυνδυασμένα αντισώματα κατά της υπομονάδας που αναγνωρίζει με ειδικότητα κατάλοιπα μαννόζης (anti-CDR4-MR human recombinant antibodies (scFv) μετά από σάρρωση βιβλιοθήκης ζύμης που εκφράζει στην επιφάνειά της ανασυνδυασμένα αντισώματα. Τα αντισώματα αυτά παρεμπόδισαν την πρόσδεση της μεσοθηλίνης. Επιπλέον, ο κλώνος #G11, απέτρεψε την πόλωση των μακροφάγων σε φαινότυπο TAM. Αυτό αποδεικνύει πως παράγοντες ικανοί να ρυθμίζουν την πόλωση των μακροφάγων στο καρκινικό μικροπεριβάλλον είναι δυνατόν να πυροδοτήσουν την απόρριψη του όγκου από τοανοσοποιητικό σύστημα.Για να διευρύνουμε τη στόχευση των σχετιζόμενων με τον καρκίνο μακροφάγων (ΤΑΜ), μελετήσαμε επίσης την γλυκοπρωτείνη Β7-Η4 που 1) αντιπροσωπεύει έναν από τους σημαντικούς καταστολείς των Τ λεμφοκυττάρων, 2) υπερεκφράζεταιι στα ΤΑΜ και 3) συσχετίζεται με αυξημένη επιθετικότητα και κακή πρόγνωση για την επιβίωση των ασθενών με καρκίνο των ωοθηκών. Μετά από ανάλυση πρωτογενών καρκινικών κυττάρων από ασκίτες ή συμπαγείς όγκους ή από ποντικούς στους οποίους είχαν δημιουργηθεί όγκοι ωοθήκης, εντοπίσαμε αυξημένη έκφραση του Β7-Η4 στην κυτταρική επιφάνεια. Επίσης, βρήκαμε πως τα διηθούμενα στον όγκο μακροφάγα παρουσίαζαν αυξημένη επιφανειακή έκφραση του Β7-Η4. Για τη στόχευση του Β7-Η4 των καρκινικών κυττάρων και των ανοσοκατασταλτικών ΤΑΜ, απομονώσαμε ανασυνδυασμένα αντισώματα. Επιλεγμένοι κλώνοι αντισωμάτων κατά του Β7-Η4 μελετήθηκαν λεπτομερώς για την ικανότητά τους να παρεμποδίζουν την ανοσοκατασταλτική δράση του Β7-Η4. Τα αποτελέσματά μας έδειξαν ότι ο κλώνος 3#54 μπορούσε να αντιστρέψει την καταστολή της ενεργότητας Τ λεμφοκυττάρων μετά από ομοιοπολική ενεργοποίηση μέσω του CD3 μορίου παρουσία της ανασυνδυασμένης Β7-Η4 πρωτεΐνης. Επιπλέον, αποδείξαμε ότι το B7-H4 που εκφράζεται in cis από αντιγονοπαρουσιαστικά κύτταρα και καρκινικά κύτταρα ή in trans από ΤΑΜs μειώνει την ενεργοποίηση Τ κυττάρων με ειδικότητα για καρκινικά αντίγονα κατόπιν αναγνώρισης των κυττάρων-στόχων τους. Τo ανασυνδυασμένο αντίσωμα κατά του B7-H4 3#54 από την άλλη, εξουδετερώνει την αρνητική επίδραση του Β7-Η4 προάγοντας την ανοσολογική απόκριση των Τ λεμφοκυττάρων κατά των καρκινικών στόχων ή κυττάρων που παρουσιάζουν τον αντιγονικό επίτοπο. Ανακεφαλαιώνοντας, στην παρούσα εργασία μελετήσαμε τον ρόλο της υπερέκφρασης των γλυκοπρωτεϊνών μεσοθηλίνη, CA125, MR και B7-H4. Οι συγκεκριμένες αποτελούν σημαντικούς διαγνωστικούς και προγνωστικούς δείκτες στον καρκίνο των ωοθηκών. Μελετήσαμε την πρόσδεση αυτών των αντιγόνων σε μακροφάγα ή σε Τ λεμφοκύτταρα και αποκαλύψαμε σημαντικές συνέπειες των αλληλεπιδράσεων αυτών για την ανοσολογική απόκριση έναντι καρκινικών κυττάρων. Τέλος, απομονώσαμε ανασυνδυασμένα αντισώματα έναντι των παραπάνω γλυκοπρωτεϊνών και διερευνήσαμε την εφαρμογή τους σε πειραματικές μελέτες για την ανάπτυξη νέων θεραπευτικών μεθόδων στον καρκίνο των ωοθηκών.

scholarly journals Astaxanthin Treatment Induces Maturation and Functional Change of Myeloid-Derived Suppressor Cells in Tumor-Bearing Mice

Antioxidants ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 350
Author(s):  
Seong Mun Jeong ◽  
Yeon-Jeong Kim
Keyword(s):  
Mhc Class Ii ◽  
Target Genes ◽  
Suppressor Cells ◽  
Functional Change ◽  
Related Factor ◽  
Mrna Levels ◽  
Myeloid Derived Suppressor Cells ◽  
Antitumor Effects

Myeloid-derived suppressor cells (MDSCs) are immature myeloid cells which accumulate in stress conditions such as infection and tumor. Astaxanthin (ATX) is a well-known antioxidant agent and has a little toxicity. It has been reported that ATX treatment induces antitumor effects via regulation of cell signaling pathways, including nuclear factor erythroid-derived 2-related factor 2 (Nrf2) signaling. In the present study, we hypothesized that treatment with ATX might induce maturation of MDSCs and modulate their immunosuppressive activity. Both in vivo and in vitro treatment with ATX resulted in up-regulation of surface markers such as CD80, MHC class II, and CD11c on both polymorphonuclear (PMN)-MDSCs and mononuclear (Mo)-MDSCs. Expression levels of functional mediators involved in immune suppression were significantly reduced, whereas mRNA levels of Nrf2 target genes were increased in ATX-treated MDSCs. In addition, ATX was found to have antioxidant activity reducing reactive oxygen species level in MDSCs. Finally, ATX-treated MDSCs were immunogenic enough to induce cytotoxic T lymphocyte response and contributed to the inhibition of tumor growth. This demonstrates the role of ATX as a regulator of the immunosuppressive tumor environment through induction of differentiation and functional conversion of MDSCs.

scholarly journals Staphylococcus aureus biofilm elicits the expansion, activation and polarization of myeloid-derived suppressor cells in vivo and in vitro

PLoS ONE ◽  
2017 ◽  
Vol 12 (8) ◽  
pp. e0183271 ◽  
Author(s):  
Kuo-Ti Peng ◽  
Ching-Chuan Hsieh ◽  
Tsung-Yu Huang ◽  
Pei-Chun Chen ◽  
Hsin-Nung Shih ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Suppressor Cells ◽  
Myeloid Derived Suppressor Cells

scholarly journals Glucosamine Interferes With Myelopoiesis and Enhances the Immunosuppressive Activity of Myeloid-Derived Suppressor Cells

2021 ◽  
Vol 8 ◽  
Author(s):  
Eric Chang-Yi Lin ◽  
Shuoh-Wen Chen ◽  
Luen-Kui Chen ◽  
Ting-An Lin ◽  
Yu-Xuan Wu ◽  
...  
Keyword(s):  
Glucose Transporter ◽  
Immune Cell ◽  
Suppressor Cells ◽  
Therapeutic Benefit ◽  
Myeloid Derived Suppressor Cells ◽  
Hematopoietic Stem ◽  
Glucose Transporter 1 ◽  
Arginase 1

Glucosamine (GlcN) is the most widely consumed dietary supplement and exhibits anti-inflammatory effects. However, the influence of GlcN on immune cell generation and function is largely unclear. In this study, GlcN was delivered into mice to examine its biological function in hematopoiesis. We found that GlcN promoted the production of immature myeloid cells, known as myeloid-derived suppressor cells (MDSCs), both in vivo and in vitro. Additionally, GlcN upregulated the expression of glucose transporter 1 in hematopoietic stem and progenitor cells (HSPCs), influenced HSPC functions, and downregulated key genes involved in myelopoiesis. Furthermore, GlcN increased the expression of arginase 1 and inducible nitric oxide synthase to produce high levels of reactive oxygen species, which was regulated by the STAT3 and ERK1/2 pathways, to increase the immunosuppressive ability of MDSCs. We revealed a novel role for GlcN in myelopoiesis and MDSC activity involving a potential link between GlcN and immune system, as well as the new therapeutic benefit.

scholarly journals IMMU-28. TARGETING IMMUNOSUPPRESSIVE MYELOID DERIVED SUPPRESSOR CELLS VIA MIF/CD74 SIGNALING AXIS TO ATTENUATE GBM GROWTH

2019 ◽  
Vol 21 (Supplement_6) ◽  
pp. vi125-vi125
Author(s):  
Tyler Alban ◽  
Defne Bayik ◽  
Balint Otvos ◽  
Matthew Grabowski ◽  
Manmeet Ahluwalia ◽  
...  
Keyword(s):  
Tumor Microenvironment ◽  
Tumor Growth ◽  
Immune Cell ◽  
Suppressor Cells ◽  
Myeloid Derived Suppressor Cells ◽  
Signaling Axis ◽  
Immunosuppressive Microenvironment ◽  
And Function

Abstract The immunosuppressive microenvironment in glioblastoma (GBM) enables persistent tumor growth and evasion from tumoricidal immune cell recognition. Despite a large accumulation of immune cells in the GBM microenvironment, tumor growth continues, and evidence for potent immunosuppression via myeloid derived suppressor cells (MDSCs) is now emerging. In agreement with these observations, we have recently established that increased MDSCs over time correlates with poor prognosis in GBM, making these cells of interest for therapeutic targeting. In seeking to reduce MDSCs in GBM, we previously identified the cytokine macrophage migration inhibitory factor (MIF) as a possible activator of MDSC function in GBM. Here, using a novel in vitro co-culture system to reproducibly and rapidly create GBM-educated MDSCs, we observed that MIF was essential in the generation of MDSCs and that MDSCs generated via this approach express a repertoire of MIF receptors. CD74 was the primary MIF receptor in monocytic MDSCs (M-MDSC), which penetrate the tumor microenvironment in preclinical models and patient samples. A screen of MIF/CD74 interaction inhibitors revealed that MN-166, a clinically relevant blood brain barrier penetrant drug, which is currently fast tracked for FDA approval, reduced MDSC generation and function in vitro. This effect was specific to M-MDSC subsets expressing CD74, and appeared as reduced downstream pERK signaling and MCP-1 secretion. In vivo, MN-166 was able reduce tumor-infiltrating MDSCs, while conferring a significant increase in survival in the syngeneic glioma model GL261. These data provide proof of concept that M-MDSCs can be targeted in the tumor microenvironment via MN-166 to reduce tumor growth and provide a rationale for future clinical assessment of MN-166 to reduce M-MDSCs in the tumor microenvironment. Ongoing studies are assessing the effects of MDSC inhibition in combination with immune activating approaches, in order to inhibit immune suppression while simultaneously activating the immune system.

Myeloid-derived suppressor cells as a potential treatment target for pancreas adenocarcinoma.

2011 ◽  
Vol 29 (4_suppl) ◽  
pp. 194-194
Author(s):  
M. R. Porembka ◽  
J. B. Mitchem ◽  
P. S. Goedegebuure ◽  
D. Linehan
Keyword(s):  
T Cells ◽  
Tumor Growth ◽  
Animal Studies ◽  
Suppressor Cells ◽  
Disease Stage ◽  
Tumor Growth Rate ◽  
Myeloid Derived Suppressor Cells ◽  
Pancreas Adenocarcinoma

194 Background: Myeloid-derived suppressor cells (MDSC) are a heterogeneous population of immunosuppressive cells that are upregulated in cancer. Little is known about the prevalence and importance of MDSC in pancreas adenocarcinoma (PA). Here, we quantify MDSC prevalence in patients with PA and assess the efficacy of MDSC depletion in a murine model of PA. Methods: Peripheral blood and tumor samples were collected from patients with PA, analyzed for MDSC (CD15+11b+) by flow cytometry (FC) and compared to cancer-free controls (CFC). The suppressive capacity of MDSC and the effectiveness of MDSC depletion were assessed in C57BL/6 mice inoculated with Pan02, a murine PA, and treated with placebo or zoledronic acid (ZA), a potent aminobisphosphonate previously shown to target MDSC. Endpoints included tumor size, survival, and MDSC prevalence. Tumor cell infiltrate was analyzed by FC for MDSC (Gr1+CD11b+) and effector T cells; tumor cytokine levels were measured by Luminex assay. Results: Patients with PA demonstrated increased circulating MDSC compared to CFC, which correlated with disease stage (metastatic PA: 68%±3.6% of CD45+ cells, resectable PA: 57%±3.5%, CFC: 37%±3.6%; p<0.0001). Normal pancreas tissue showed no MDSC infiltrate while PA avidly recruited CD11b+15+ cells to the primary tumor. Murine tumors similarly recruited MDSC that actively suppressed CD8+ T cells in vitro measured by CFSE dilution and accelerated tumor growth in vivo by adoptive transfer with Pan02 cells (p<0.001). Treatment with ZA impaired MDSC accumulation in the tumor (Placebo: 78%, ZA: 51%, p<0.05) resulting in delayed tumor growth rate (p<0.0001) and prolonged median survival (Placebo: 59 days, ZA: 73 days, p<0.05). MDSC blockade increased recruitment of T cells to the tumor (CD4: 4.4%±1.1% vs 12.2%±2.0%, p<0.05; CD8: 3.9%±1.3% vs 10.6%±2.2%, p<0.05) and a more robust type 1 response with increased levels of IFN-g (p<0.05) and decreased levels of IL-10 (p<0.05). Conclusions: MDSC are an important mediator of tumor-induced immunosuppression in PA. Treatment with ZA effectively blocks MDSC accumulation improving anti-tumor response in animal studies. Efforts to block MDSC may represent a novel treatment strategy for PA. [Table: see text]

Small Molecule SHIP Agonist AQX-MN100 Inhibits Multiple Myeloma (MM) Cell Growth In NOD/SCID Mice and Reduces Immune Suppressive Myeloid Derived Suppressor Cells (MDSC) and Regulatory T Cells (Tregs) In Mouse Model

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 792-792
Author(s):  
Alice Mui ◽  
Mike Kennah ◽  
Christopher Ong ◽  
Raymond Anderson ◽  
Heather Sutherland
Keyword(s):  
Tumor Volume ◽  
Suppressor Cells ◽  
Pi3k Pathway ◽  
Akt Signaling ◽  
Myeloid Derived Suppressor Cells ◽  
Hemopoietic Cells ◽  
Equity Ownership

Abstract Abstract 792 We recently described a novel anti-MM drug (AQX-MN100) which is a small molecule agonist of SHIP (Src homology-2 (SH2) containing inositol-5¢-phosphatase) a signaling molecule found only in hemopoietic cells.(Ong et al, Blood; 110:1942, 2007) The molecule was developed using a high-throughput SHIP enzyme assay to screen an invertebrate marine natural product library and isolate the Pelorol.(Yang et al Org Lett; 7:1073, 2005) SHIP normally functions to negatively regulate the PI3K pathway important to normal hemopoietic cells growth and function. Inappropriate activation of the phosphoinositide 3- kinase (PI3K) pathway has been shown to be involved in the pathogenesis of MM and tumour aggressiveness correlates with the degree of activation. The critical role the PI3K/Akt signaling pathway plays in regulating MM cell survival, has stimulated efforts in designing therapeutics that target this pathway. Pan PI3K inhibitors have limited utility in a clinical setting because of their inhibitory effects on all isoforms of the PI3K family as well as non-PI3K targets. SHIP is an exceptionally good target for MM and other hematopoietic disorders that display elevated PI3K/Akt signaling because its expression is restricted to hemopoietic cells. We have shown that an analogue of Pelorol, AQX-MN100 is able to inhibit PI3K signaling and prevent phosphorylation of Akt. AQX-MN100 induced MM cell line apoptosis mediated by caspase and was specific for SHIP expressing cells which are exclusively hematopoietic. AQX-MN100 also enhances the growth inhibition effects of current myeloma drugs Dexamethasone and Bortezomib on human MM tumour cell lines in vitro. (Kennah et al Expt Hematol; 37:1274, 2009) In this study we have extended these finding to further evaluate the role of this compound in the treatment of myeloma. NOD-SCID mice were injected in the lateral flanks with 2 million luciferase tagged MM1.S multiple myeloma cells in Matrigel. Tumors were allowed to establish for two weeks and then either AQX-MN100 or vehicle was administered in an oil deposit subcutaneously in the lower flank at a dose of 50 mg/kg every three days. Tumor volume was quantified by imaging on a Xenogen IVIS 200 after 6 and 11 days. These studies demonstrate a significant reduction of tumor volume at 6 days p<0.05 and a highly significant reduction at 11 days p<0.01 in the mice receiving AQX-MN100 as compared to vehicle. We have shown that AQX-MN100 can directly kill MM cells in in vitro and in vivo. However, based on the known functions of SHIP, we predict that SHIP agonists will additionally target critical steps in MM pathogenesis in vivo, including the ability of MM cells to interact with stromal elements and to subvert the immune system. In order to evaluate this later feature we evaluated the ability of SHIP agonists to reverse the tumor associated immune suppression in MM patients. Tumor and host cell/tumor microenvironment secreted factors promote the production and activation of cells associated with cancer progression: the immune suppressive myeloid derived suppressor cells (MDSC) and regulatory T cells (Tregs). These cells normally regulate immune responses by inhibiting the activation of immune effector cells. The involvement of SHIP in the regulation of these cells is predicted by the observation that MDSC and Treg numbers are elevated in SHIP deficient mice. In this study Balb/C mice, 6 mice/group in duplicate were given either AQX-MN100 3 mg/kg and 10 mg/kg or vehicle once daily orally. At the end of three weeks mesenteric lymph nodes were harvested and subjected to FACS analysis to determine the proportion of MDSC (CD11b+Gr1+) and Treg (CD4+CD25+FoxP3+) cells. Spleen cells were also analysed for B cells, NK cells and granulocytes. In both of the AQX-MN100 treated groups the numbers of MDSC and Tregs were significantly lower than controls while Total CD11b, Total CD3, and spleen B, NK and granulocytes were not different from vehicle treated controls. The known role of SHIP in regulating hemopoietic cell function and the role of SHIP agonists in MM cell killing as well as additional actions on other aspects of MM pathophysiology may make them a powerful treatment option for MM, either alone or in synergy with other known MM therapies. Further development of this agent for the treatment of MM is ongoing. Disclosures: Mui: Aquinox: Equity Ownership, Patents & Royalties. Ong:Aquinox: Equity Ownership, Patents & Royalties. Anderson:Aquinox: Equity Ownership, Patents & Royalties. Sutherland:Celgene: Honoraria; Orthobiotech: Honoraria.

scholarly journals Fibrinogen and fibronectin binding cooperate for valve infection and invasion in Staphylococcus aureus experimental endocarditis

2005 ◽  
Vol 201 (10) ◽  
pp. 1627-1635 ◽  
Author(s):  
Yok-Ai Que ◽  
Jacques-Antoine Haefliger ◽  
Lionel Piroth ◽  
Patrice François ◽  
Eleonora Widmer ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Binding Domain ◽  
Disease Evolution ◽  
Cell Internalization ◽  
Fibrinogen Binding ◽  
In Trans ◽  
Fibronectin Binding ◽  
In Cis

The expression of Staphylococcus aureus adhesins in Lactococcus lactis identified clumping factor A (ClfA) and fibronectin-binding protein A (FnBPA) as critical for valve colonization in rats with experimental endocarditis. This study further analyzed their role in disease evolution. Infected animals were followed for 3 d. ClfA-positive lactococci successfully colonized damaged valves, but were spontaneously eradicated over 48 h. In contrast, FnBPA-positive lactococci progressively increased bacterial titers in vegetations and spleens. At imaging, ClfA-positive lactococci were restricted to the vegetations, whereas FnBPA-positive lactococci also invaded the adjacent endothelium. This reflected the capacity of FnBPA to trigger cell internalization in vitro. Because FnBPA carries both fibrinogen- and fibronectin-binding domains, we tested the role of these functionalities by deleting the fibrinogen-binding domain of FnBPA and supplementing it with the fibrinogen-binding domain of ClfA in cis or in trans. Deletion of the fibrinogen-binding domain of FnBPA did not alter fibronectin binding and cell internalization in vitro. However, it totally abrogated valve infectivity in vivo. This ability was restored in cis by inserting the fibrinogen-binding domain of ClfA into truncated FnBPA, and in trans by coexpressing full-length ClfA and truncated FnBPA on two separate plasmids. Thus, fibrinogen and fibronectin binding could cooperate for S. aureus valve colonization and endothelial invasion in vivo.

scholarly journals Expansion of myeloid-derived suppressor cells contributes to metabolic osteoarthritis through subchondral bone remodeling

2021 ◽  
Vol 23 (1) ◽  
Author(s):  
Lixia Zhang ◽  
Cameron L. Kirkwood ◽  
Jiho Sohn ◽  
Ashley Lau ◽  
Mary Bayers-Thering ◽  
...  
Keyword(s):  
Metabolic Disease ◽  
Subchondral Bone ◽  
Peripheral Blood ◽  
Significant Proportion ◽  
Suppressor Cells ◽  
Myeloid Derived Suppressor Cells ◽  
Joint Injury ◽  
Myeloid Progenitor Cells

Abstract Background Osteoarthritis (OA) subsequent to acute joint injury accounts for a significant proportion of all arthropathies. Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of myeloid progenitor cells classically known for potent immune-suppressive activity; however, MDSCs can also differentiate into osteoclasts. In addition, this population is known to be expanded during metabolic disease. The objective of this study was to determine the role of MDSCs in the context of OA pathophysiology. Methods In this study, we examined the differentiation and functional capacity of MDSCs to become osteoclasts in vitro and in vivo using mouse models of OA and in MDSC quantitation in humans with OA pathology relative to obesity status. Results We observed that MDSCs are expanded in mice and humans during obesity. MDSCs were expanded in peripheral blood of OA subjects relative to body mass index and in mice fed a high-fat diet (HFD) compared to mice fed a low-fat diet (LFD). In mice, monocytic MDSC (M-MDSC) was expanded in diet-induced obesity (DIO) with a further expansion after destabilization of the medial meniscus (DMM) surgery to induce post-traumatic OA (PTOA) (compared to sham-operated controls). M-MDSCs from DIO mice had a greater capacity to form osteoclasts in culture with increased subchondral bone osteoclast number. In humans, we observed an expansion of M-MDSCs in peripheral blood and synovial fluid of obese subjects compared to lean subjects with OA. Conclusion These data suggest that MDSCs are reprogrammed in metabolic disease, with the potential to contribute towards OA progression and severity.

Molecular contortionism – on the physical limits of serpin ‘loop-sheet’ polymers

2010 ◽  
Vol 391 (8) ◽  
Author(s):  
James A. Huntington ◽  
James C. Whisstock
Keyword(s):  
Proper Function ◽  
Alternative Mechanism ◽  
Polymer Properties ◽  
Reactive Centre Loop ◽  
Partial Unfolding ◽  
In Trans ◽  
In Cis ◽  
Β Sheet

Abstract Members of the serpin (serine protease inhibitor) superfamily fold into a metastable conformation that is crucial for proper function. As a consequence, serpins are susceptible to mutations that cause misfolding and the intracellular accumulation of pathogenic polymers. The mechanism of serpin polymerisation remains to be resolved, however, over the past two decades the ‘loop-sheet’ hypothesis has gained wide acceptance. In this mechanism the reactive centre loop of one serpin monomer inserts into the β-sheet A of another (in trans), in a manner similar to what is seen for reactive centre loop-cleaved and latent conformations (in cis). The hypothesis has been refined in response to certain experimental data, but it has proved difficult to assess the various propositions without creating molecular models. Here we evaluate the loop-sheet mechanism by creating models of pentamers of the archetypal serpin α1-antitrypsin. We conclude that an inescapable consequence of the loop-sheet mechanism is polymer compaction and rigidity, properties that are inconsistent with the ‘beads-on-a-string’ morphology of polymers obtained from human tissue. The recent crystal structure of a domain-swapped serpin dimer suggests an alternative mechanism that is consistent with known polymer properties, including the requirement of partial unfolding to induce polymer formation in vitro, and polymerisation from a folding intermediate in vivo.

scholarly journals Identification of monocyte-like precursors of granulocytes in cancer as a mechanism for accumulation of PMN-MDSCs

2019 ◽  
Vol 216 (9) ◽  
pp. 2150-2169 ◽  
Author(s):  
Jérôme Mastio ◽  
Thomas Condamine ◽  
George Dominguez ◽  
Andrew V. Kossenkov ◽  
Laxminarasimha Donthireddy ◽  
...  
Keyword(s):  
Suppressor Cells ◽  
Myeloid Derived Suppressor Cells ◽  
Monocytic Cells ◽  
Tumor Bearing ◽  
Hla Dr ◽  
Selective Targeting ◽  
Selective Depletion ◽  
Monocytic Lineage

We have identified a precursor that differentiates into granulocytes in vitro and in vivo yet belongs to the monocytic lineage. We have termed these cells monocyte-like precursors of granulocytes (MLPGs). Under steady state conditions, MLPGs were absent in the spleen and barely detectable in the bone marrow (BM). In contrast, these cells significantly expanded in tumor-bearing mice and differentiated to polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs). Selective depletion of monocytic cells had no effect on the number of granulocytes in naive mice but decreased the population of PMN-MDSCs in tumor-bearing mice by 50%. The expansion of MLPGs was found to be controlled by the down-regulation of Rb1, but not IRF8, which is known to regulate the expansion of PMN-MDSCs from classic granulocyte precursors. In cancer patients, putative MLPGs were found within the population of CXCR1+CD15−CD14+HLA-DR−/lo monocytic cells. These findings describe a mechanism of abnormal myelopoiesis in cancer and suggest potential new approaches for selective targeting of MDSCs.

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