Browsing by Author "Salih, Bekir"

Now showing 1 - 4 of 4

Open Access
Circulating extracellular vesicles of patients with steroid-sensitive nephrotic syndrome have higher RAC1 and induce recapitulation of nephrotic syndrome phenotype in podocytes
(American Physiological Society, 2021-11-09) Kara Eroğlu, Fehime; Yazar, Volkan; Guler, Ulku; Yıldırım, Muzaffer; Yıldırım, Tuğçe; Gungor, Tulin; Celikkaya, Evra; Karakaya, Deniz; Turay, Nilsu; Ciftci Dede, Eda; Korkusuz, Petek; Salih, Bekir; Bulbul, Mehmet; Gürsel, İhsan
Since previous research suggests a role of a circulating factor in the pathogenesis of steroid-sensitive nephrotic syndrome (NS), we speculated that circulating plasma extracellular vesicles (EVs) are a candidate source of such a soluble mediator. Here, we aimed to characterize and try to delineate the effects of these EVs in vitro. Plasma EVs from 20 children with steroid-sensitive NS in relapse and remission, 10 healthy controls, and 6 disease controls were obtained by serial ultracentrifugation. Characterization of these EVs was performed by electron microscopy, flow cytometry, and Western blot analysis. Major proteins from plasma EVs were identified via mass spectrometry. Gene Ontology classification analysis and Ingenuity Pathway Analysis were performed on selectively expressed EV proteins during relapse. Immortalized human podocyte culture was used to detect the effects of EVs on podocytes. The protein content and particle number of plasma EVs were significantly increased during NS relapse. Relapse NS EVs selectively expressed proteins that involved actin cytoskeleton rearrangement. Among these, the level of RAC-GTP was significantly increased in relapse EVs compared with remission and disease control EVs. Relapse EVs were efficiently internalized by podocytes and induced significantly enhanced motility and albumin permeability. Moreover, relapse EVs induced significantly higher levels of RAC-GTP and phospho-p38 and decreased the levels of synaptopodin in podocytes. Circulating relapse EVs are biologically active molecules that carry active RAC1 as cargo and induce recapitulation of the NS phenotype in podocytes in vitro.
Embargo
Enhancing preventive and therapeutic cancer vaccine efficacy through biotherapeutic ligand-associated extracellular vesicles
(Elsevier Ltd, 2024-12) Kahraman, Tamer; Akpınar, Gözde Güçlüler; Yıldırım, Muzaffer; Larssen, Pia; Bayyurt-Kocabaş, Banu; Yağcı, Fuat Cem; Gürsel, Arda; Horuluoğlu, Begüm Han; Yazar, Volkan; Ayanoğlu, İhsan Cihan; Yıldırım, Tuğce Canavar; Evcili, İrem; Yılmaz, İsmail Cem; Eldh, Maria; Gabrielsson, Susanne; Güler, Ülkü; Salih, Bekir; Gursel, Mayda; Gürsel, İhsan
Extracellular vesicles (EVs), secreted by almost all living cells, have gained significant attention for their role in intercellular communication and their potential as versatile carriers for biotherapeutics. However, the clinical translation of EV-based therapies faces significant challenges, primarily due to the lack of efficient methods for loading biotherapeutic agents into EVs. This study introduces a simple, reproducible strategy for the simultaneous incorporation of various biotherapeutics within EVs. The process is gentle and preserves the essential physicochemical and biological characteristics of EVs, thereby protecting labile ligands from premature degradation and elimination. The binding and uptake efficiency of EVs by target cells reached approximately 97 % within 24 h of incubation. Administration of EVs loaded with oligodeoxynucleotides (ODN) resulted in a 4-fold increase in $IFNy^{+}$ $CD4^{+}$ T cells and a 5-fold increase in $IFNy^{+}$ $CD8^{+}$ T cells in the spleens and lymph nodes. Additionally, the co-administration of EVs with ODN and ovalbumin (OVA) induced elevated Th1-biased antibody responses and antigen-specific cytotoxic T-cell responses, providing long-lasting complete protection in 60 % of mice against T-cell thymoma challenge. Furthermore, EVs associated with three different ligands (OVA, CpG-ODN, and α-GalCer) effectively regressed established murine melanoma and significantly improved survival rates in mice. This study presents a powerful and promising approach to overcoming the limitations of EV-based cancer vaccines, advancing the development of effective cancer immunotherapies.
Open Access
Immunogenicity and protective capacity of a CpG ODN adjuvanted alum adsorbed bivalent meningococcal outer membrane vesicle vaccine
(Oxford University Press, 2024-03-27) Yıldırım, Tuğçe Canavar; Özsürekçi, Yasemin; Yıldırım, Muzaffer; Evcili, İrem; Yazar, Volkan; Aykaç, Kübra; Güler, Ülkü; Salih, Bekir; Gürsel, Mayda; Gürsel, İhsan
Invasive meningococcal disease (IMD) is caused by Neisseria meningitidis, with the main serogroups responsible for the disease being A, B, C, W, X, and Y. To date, several vaccines targeting N. meningitidis have been developed albeit with a short-lived protection. Given that MenW and MenB are the most common causes of IMD in Europe, Turkey, and the Middle East, we aimed to develop an outer membrane vesicle (OMV) based bivalent vaccine as the heterologous antigen source. Herein, we compared the immunogenicity, and breadth of serum bactericidal activity (SBA) assay-based protective coverage of OMV vaccine to the X serotype with existing commercial meningococcal conjugate and polysaccharide (PS) vaccines in a murine model. BALB/c mice were immunized with preclinical batches of the W + B OMV vaccine, either adjuvanted with Alum, CpG ODN, or their combinations, and compared with a MenACYW conjugate vaccine (Nimenrix^TM, Pfizer), and a MenB OMV-based vaccine (Bexsero®, GSK), The immune responses were assessed through enzyme-linked immunosorbent assay (ELISA) and SBA assay. Antibody responses and SBA titers were significantly higher in the W + B OMV vaccine when adjuvanted with Alum or CpG ODN, as compared to the control groups. Moreover, the SBA titers were not only significantly higher than those achieved with available conjugated ACYW vaccines but also on par with the 4CMenB vaccines. In conclusion, the W + B OMV vaccine demonstrated the capacity to elicit robust antibody responses, surpassing or matching the levels induced by licensed meningococcal vaccines. Consequently, the W + B OMV vaccine could potentially serve as a viable alternative or supplement to existing meningococcal vaccines.
Open Access
Leishmania extracellular vesicles mediate protection against cutaneous leishmaniasis
(Wiley, 2024-09) Tokmak, İbrahim; Yılmaz, İsmail Cem; Giirse, Muzaffer Mayda; Yazar, Volkan; Salih, Bekir; Güler, Ülkü; Gürsel, İhsan; Gürsel, Mayda