Browsing by Author "Pepe, Nihan Aktas"

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Citation - WoS: 1
Citation - Scopus: 1
Cinnamomum Zeylanicum Extract Incorporated Electrospun Poly(Lactic Acid)/ Gelatin Membrane as a New Wound Dressing
(Elsevier, 2025) Tarhan, Seray Zora; Pepe, Nihan Aktas; Sen, Alaattin; Isoglu, Ismail Alper
In this study, we fabricated poly(lactic acid)/gelatin electrospun membranes containing various concentrations of Cinnamomum zeylanicum extract and evaluated them as a novel wound dressing. The electrospun membranes were chemically, morphologically, and mechanically characterized, and the results were discussed in comparison with the literature. Electrospun membranes' biodegradability, swelling, and release properties were evaluated, with the CE7.5 membrane having values of 29.60 f 7.20 and 542.1 f 48.3 % and 66.9 %, respectively. Antibacterial activity was observed in CE7.5 and CE10 membranes against E. coli and S. aureus strains. At the highest concentration (CE10), 111.7 f 5.6 % and 96 f 12.375 % cell viability were detected in fibroblasts and differentiated LPS-induced THP-1 cells. Cell viability was further evaluated by Annexin-V/PI staining, revealing that 97.95 f 1.63 % of the cells remained viable in the CE7.5-treated membranes, while only 1.85 f 1.49 % of necrotic cells were detected in the treated cell population. Fibroblasts treated with the CE7.5 membrane showed a 42 % improvement in wound closure compared to non-treated cells. The anti-inflammatory properties of the electrospun membranes were also investigated. Treatment with the conditioned CE7.5 membrane downregulated Tba1 and tau proteins by 45.1 and 51.055 %, respectively. This study concluded that the newly developed Cinnamomum zeylanicum extract incorporated poly(lactic acid)/gelatin electrospun membranes could be a promising wound dressing material.
Efficacy of Combinatorial Inhibition of Hedgehog and Autophagy Pathways on the Survival of AML Cell Lines
(Academic Press inc Elsevier Science, 2025) Sansacar, Merve; Pepe, Nihan Aktas; Akcok, Emel Basak Gencer; El Khatib, Mona; Gencer Akçok, Emel Başak
Acute myeloid leukemia (AML) is a common hematopoietic disease that results from diverse genetic abnormalities. Dysregulation of important signaling pathways, including the PI3K/AKT/mTOR, Wnt and Hedgehog pathways, plays crucial roles in the development of AML. Hedgehog pathway (Hh) is a conserved signaling pathway that is crucial throughout embryogenesis. Hh plays an important role in the regulation of autophagy, known as the cellular recycling process of organelles and unwanted proteins. Many studies have noted that the modulation of autophagy could act as a survival mechanism in AML. Considering the pivotal role of autophagy and Hh signaling in AML, understanding the relationship between these pathways is important for overcoming leukemia. Therefore, we examined the efficacy of Hh inhibition by GLI-ANTagonist 61 (GANT61) in MOLM-13 and CMK cells via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenil-2H-tetrazolium bromide (MTT) cell viability assays. GANT61 resulted in decreased cell viability in both cell lines. Therefore, we focused on the outcome of autophagy modulation in AML cells. We observed that the autophagy inhibitors ammonium chloride (NH4CI), chloroquine (CQ), and nocodazole led to a significant reduction in the proliferation of both cell lines. Cotreatment with autophagy pathway inhibitors and GANT61 synergistically affected both AML cell lines. Moreover, dual targeting of these pathways resulted in arrest at the G0/G1 phase in MOLM-13 cells but not in CMK cells. Furthermore, the combination of nocodazole and GANT61 increased the expression level of LC3B-II in both cell lines. Compared with that in the untreated control cells, the GLI1 gene expression level in both cell lines was significantly lower after GANT61 and autophagy cotreatment. In conclusion, targeting Hh and autophagy could be a favorable option to combat AML.
Neuroinflammatory Human Brain Organoids Enable Comprehensive Drug Screening Studies: Fingolimod and Its Analogues in Focus
(Bentham Science Publishing Ltd, 2026) Acar, Busra; Pepe, Nihan Aktas; Zivkovic, Aleksandra; Stark, Holger; Sen, Alaattin
Introduction The absence of physiologically relevant models for neuroinflammatory brain disorders, such as multiple sclerosis (MS), highlights the need for improved drug screening platforms. To bridge this gap, this study aimed to develop a human brain organoid (hBO) model incorporating essential neural cell types, including astrocytes, microglia, and oligodendrocytes.Methods hBOs were generated from H9 stem cells, and neuroinflammatory characteristics were elicited by lipopolysaccharide (LPS). The expression of specific neuronal and inflammatory markers was assessed through qRT-PCR, immunofluorescence staining (IFS), and ELISA.Results IFS of mature hBOs with anti-SOX2, anti-SATB2, anti-MAPT, anti-GFAP, anti-MBP, and anti-IBA1 antibodies and images collected with the confocal microscope confirmed the differentiation of H9 cells into cortical neurons, astrocytes, microglia, and oligodendrocyte cell types. Elevated GFAP, IBA1, NF-kappa B, and IL-6 levels, along with reduced CNPase expression with LPS treatment, were considered reflective of MS-like pathology and were used to test fingolimod and its derivatives. Fingolimod and all its derivatives, specifically ST-1505, decreased MAPT (2.1-fold in ELISA, 1.7-fold in IFS), GFAP (1.8-fold in IFS), TNF alpha (5.4-fold in qRT-PCR), and FABP (1.5-fold in ELISA) levels, and increased IL-10 (11-fold in qRT-PCR) and MBP (2.9-fold in IFS) levels.Discussion The present data collectively showed LPS to evoke neuroinflammation in the hBO model, while fingolimod and its derivatives, particularly ST-1505, exhibited significant anti-inflammatory and neuroprotective properties by counteracting these evoked changes in the hBO model.Conclusion The findings supported the applicability of brain organoids as a model system for drug screening studies for neuroinflammatory brain diseases.
Role of Long Non-Coding RNA X-Inactive Transcript (XIST) in Neuroinflammation and Myelination: Insights From Cerebral Organoids and Implications for Multiple Sclerosis
(MDPI, 2025) Pepe, Nihan Aktas; Acar, Busra; Zararsiz, Gozde Erturk; Guner, Serife Ayaz; Sen, Alaattin; Erturk Zararsiz, Gozde; Ayaz Guner, Serife; Aktas Pepe, Nihan
Background/Objectives: X-inactive-specific transcript (XIST) is a factor that plays a role in neuroinflammation. This study investigated the role of XIST in neuronal development, neuroinflammation, myelination, and therapeutic responses within cerebral organoids in the context of Multiple Sclerosis (MS) pathogenesis. Methods: Human cerebral organoids with oligodendrocytes were produced from XIST-silenced H9 cells, and the mature organoids were subsequently treated with either FTY720 or DMF. Gene expression related to inflammation and myelination was subsequently analyzed via qRT-PCR. Immunofluorescence staining was used to assess the expression of proteins related to inflammation, myelination, and neuronal differentiation. Alpha-synuclein protein levels were also checked via ELISA. Finally, transcriptome analysis was conducted on the organoid samples. Results: XIST-silenced organoids presented a 2-fold increase in the expression of neuronal stem cells, excitatory neurons, microglia, and mature oligodendrocyte markers. In addition, XIST silencing increased IL-10 mRNA expression by 2-fold and MBP and PLP1 expression by 2.3- and 0.6-fold, respectively. Although XIST silencing tripled IBA1 protein expression, it did not affect organoid MBP expression. FTY720, but not DMF, distinguished MBP and IBA1 expression in XIST-silenced organoids. Furthermore, XIST silencing reduced the concentration of alpha-synuclein from 300 to 100 pg/mL, confirming its anti-inflammatory role. Transcriptomic and gene enrichment analyses revealed that the differentially expressed genes are involved in neural development and immune processes, suggesting the role of XIST in neuroinflammation. The silencing of XIST modified the expression of genes associated with inflammation, myelination, and neuronal growth in cerebral organoids, indicating a potential involvement in the pathogenesis of MS. Conclusions: XIST may contribute to the MS pathogenesis as well as neuroinflammatory diseases such as and Alzheimer's and Parkinson's diseases and may be a promising therapeutic target.
Synthesis, Characterization, and Comprehensive in Vitro and in Silico Evaluation of the Anti-Inflammatory Potential of Novel 1,2,3-Triazole–Arylidenehydrazide/Thiazolidinone Hybrids
(Wiley-VCH verlag GmbH, 2025) Pepe, Nihan Aktas; Cakir, Furkan; Atalay, Tugba; Acar, Busra; Turgut, Gurbet Celik; Sen, Alaattin; Senol, Halil
Five novel 1,2,3-triazole/arylidenehydrazide/thiazolidinone hybrid compounds (7-11) were synthesized and characterized using NMR, HRMS, IR, and HPLC purity analysis. The cytotoxicity of these compounds was evaluated on fibroblasts and THP-1 cells, showing that all compounds were nontoxic at the tested concentrations. The wound healing assay revealed that compounds 7, 9, and 10 significantly enhanced wound closure, with a 7.74%-32.69% improvement in treated cells. Compounds 8 and 11 showed moderate effects. Anti-inflammatory activity was assessed through qRT-PCR, demonstrating that compound 10 led to the most significant reduction in proinflammatory cytokines TNF-alpha, IL-1 beta, and NF-kappa B1. In addition, the expression of Iba1 protein in THP-1 cells confirmed that compound 8 showed the strongest anti-inflammatory effect, surpassing that of aspirin. Compound 10 showed the highest inhibition of NF-kappa B signaling and iNOS activity. Molecular docking studies revealed that compounds 10 and 11 had strong binding affinities to TNF-alpha and iNOS, with compound 11 showing the most stable interactions. Molecular dynamics simulations supported these findings, indicating that compound 11 demonstrated more stable binding to both targets. Overall, the results suggest that compounds 10 and 11 are promising anti-inflammatory candidates with potential for further development in therapeutic applications for inflammatory diseases.
Citation - WoS: 5
Citation - Scopus: 5
Therapeutic Potential of Nitrogen-Substituted Oleanolic Acid Derivatives in Neuroinflammatory and Cytokine Pathways: Insights From Cell-Based and Computational Models
(Wiley-VCH Verlag GmbH, 2025) Turgut, Gurbet Celik; Pepe, Nihan Aktas; Ekiz, Yagmur Ceylan; Senol, Halil; Sen, Alaattin
This study was conducted to investigate the mechanism of the potential and anti-inflammatory properties of nitrogen-substituted oleanolic acid derivatives that can be used to treat neuroinflammatory diseases. Nitrogen-containing oleanolic acid derivatives have been evaluated for their anti-neuroinflammatory effects in vitro in neuronal and monocytic cell lines at nontoxic doses, and the production of cytokines (TNF-alpha, IL-6 and IL-17), the inflammatory enzyme induced nitric oxide synthase (iNOS) and NF-kappa B signalling under LPS-stimulated conditions, and the expression of genes associated with Alzheimer's disease have been assessed. In addition, molecular docking and molecular dynamics simulation assessments are conducted in silico. Key protein markers of neurodegenerative diseases, especially Alzheimer's disease and neuroinflammation, TAU protein levels, and microglial activation, as well as ionised calcium-binding adaptor protein-1 (IBA1) levels, were significantly reduced with the addition of oleanolic acid derivatives. LPS-induced NF-kappa B luciferase reporter activity and iNOS activity were significantly inhibited, approaching the levels in uninduced controls. The mRNA expression of proinflammatory cytokines critical for neuroinflammation, such as TNF-alpha, NF-kappa B, IL-6 and IL-17, was reduced twofold to sevenfold. Furthermore, the molecular docking and MD simulation analyses revealed potential interactions with the TNF-alpha and NF-kappa B proteins. These findings underscore the potential of oleanolic acid derivatives, particularly compound 16, as candidates for further development as therapeutic agents for neurodegenerative diseases associated with chronic inflammation.